JP6823372B2 - Light emitting device - Google Patents

Description

One aspect of the present invention relates to a light emitting element having a light emitting layer obtained by applying an electric field sandwiched between a pair of electrodes, or a display device, an electronic device, and a lighting device having the light emitting element.

One aspect of the present invention is not limited to the above technical fields. The technical field of one aspect of the invention disclosed in the present specification and the like relates to a product, a method, or a manufacturing method. Alternatively, one aspect of the invention relates to a process, machine, manufacture, or composition (composition of matter). Therefore, more specifically, the technical fields of one aspect of the present invention disclosed in the present specification include semiconductor devices, display devices, liquid crystal display devices, light emitting devices, lighting devices, power storage devices, storage devices, and driving methods thereof. Alternatively, those manufacturing methods can be given as an example.

In recent years, research and development of light emitting devices using electroluminescence (EL) have been actively carried out. The basic configuration of these light emitting elements is that a layer (EL layer) containing a luminescent substance is sandwiched between a pair of electrodes. By applying a voltage between the electrodes of this device, light emission from a luminescent substance can be obtained.

Since the above-mentioned light emitting element is a self-luminous type, a display device using the above-mentioned light emitting element has advantages such as excellent visibility, no need for a backlight, and low power consumption. Further, it can be manufactured thin and lightweight, and has advantages such as high response speed.

In the case of a light emitting element (for example, an organic EL element) in which an organic compound is used as a light emitting substance and an EL layer containing the light emitting substance is provided between a pair of electrodes, electrons are emitted from the cathode by applying a voltage between the pair of electrodes. However, holes are injected into the luminescent EL layer from the anode, and a current flows. Then, the injected electrons and holes are recombined to bring the luminescent organic compound into an excited state, and luminescence can be obtained from the excited luminescent organic compound.

There are two types of excited states formed by organic compounds: singlet excited state (S ^* ) and triplet excited state (T ^* ). Emission from the singlet excited state is fluorescence, and emission from the triplet excited state is fluorescence. It is called phosphorescence. Moreover, it is considered that their statistical generation ratio in the light emitting element is S ^* : T ^* = 1: 3. Therefore, it is possible to obtain higher luminous efficiency in a light emitting device using a phosphorescent compound than in a light emitting device using a compound that emits fluorescence. Therefore, in recent years, a light emitting device using a phosphorescent compound capable of converting a triplet excited state into light emission has been actively developed.

Among the light emitting elements using phosphorescent compounds, particularly in the light emitting element exhibiting blue light emission, it is difficult to develop a stable compound having a high triplet excitation energy level, so that it has not yet been put into practical use. Therefore, in the light emitting element exhibiting blue light emission, a light emitting element using a more stable fluorescent compound has been developed, and a method for increasing the luminous efficiency of the light emitting element (fluorescent light emitting element) using the fluorescent compound. Is being searched for.

Triplet-triplet annihilation (TTA) is known as a light emitting mechanism capable of converting a part of the triplet excited state into light emission. In TTA, the excitation energy and spin angular momentum are exchanged and transferred by the proximity of two triplet excitons, and as a result, singlet excitons are said to be generated.

As a compound that produces TTA, a compound having an anthracene skeleton is known. Non-Patent Document 1 reports that by using a compound having an anthracene skeleton as a host material of a light emitting device, an external quantum efficiency higher than 10% is exhibited in a light emitting device exhibiting blue light emission. Further, it has been reported that the ratio of the delayed fluorescent component due to TTA to the light emitting component exhibited by the light emitting device using the compound having an anthracene skeleton is about 10%.

On the other hand, as a compound having a high proportion of delayed fluorescent components due to TTA, a compound having a tetracene skeleton is known. Non-Patent Document 2 reports that the proportion of delayed fluorescent components due to TTA in light emission from a compound having a tetracene skeleton is higher than that of a compound having an anthracene skeleton.

Tsune Nori Suzuki, 6 others, Japanese Journal of Applied Physics, vol. 53, 052102 (2014) D. Y. Kondakov, 3 others, Journal of Applied Physics, vol. 106, 124510 (2009)

In a light emitting element having a fluorescent compound, in order to increase the light emission efficiency, the energy of the triplet exciter that does not contribute to light emission is converted into the energy of the luminescent singlet exciter, and the conversion efficiency is increased. Is important. That is, it is important to convert the energy of triplet excitons into the energy of singlet excitons by TTA. Further, in a light emitting device having a fluorescent compound, in order to increase the luminous efficiency, it is important to increase the ratio of the delayed fluorescent component based on TTA among the light emitting components exhibited by the light emitting device. This is because the high proportion of delayed fluorescent components based on TTA means that the proportion of luminescent singlet excitons produced is increasing.

It should be noted that not all compounds having an anthracene skeleton or a tetracene skeleton efficiently generate TTA, and some compounds generate TTA, but some compounds hardly generate TTA. However, the reason is not clear. Therefore, there is a need for a method for designing a compound that produces TTA or a compound having a high proportion of delayed fluorescent components based on TTA. Further, by using a compound having high carrier transport property as the host material of the light emitting layer in the light emitting element, the driving voltage of the light emitting element can be reduced. Therefore, if a compound having high carrier transportability and generating TTA can be designed, it is possible to manufacture a light emitting element having a low driving voltage and high luminous efficiency, that is, a light emitting element having reduced power consumption. Since the method for designing a compound that produces TTA has not been clarified, it is difficult to design a compound that has high carrier transportability and produces TTA.

Therefore, in one aspect of the present invention, it is an object of the present invention to provide a light emitting device having high luminous efficiency in a light emitting device having a fluorescent compound. Alternatively, in one aspect of the present invention, it is an object of the present invention to provide a light emitting element having high luminous efficiency in a light emitting element exhibiting blue color. Alternatively, one aspect of the present invention is to provide a light emitting device having a high proportion of delayed fluorescent components due to TTA among the light emitting components. Alternatively, in one aspect of the present invention, one of the problems is to provide a light emitting element having reduced power consumption. Alternatively, one aspect of the present invention is to provide a novel light emitting device. Alternatively, one aspect of the present invention is to provide a novel light emitting device. Alternatively, one aspect of the present invention is to provide a new display device.

The description of the above problem does not prevent the existence of other problems. It should be noted that one aspect of the present invention does not necessarily have to solve all of these problems. Issues other than the above are self-evident from the description of the specification and the like, and it is possible to extract problems other than the above from the description of the specification and the like.

In one aspect of the present invention, the light emitting element has at least an EL layer, and by efficiently generating TTA in the EL layer, a triplet exciter that does not contribute to light emission is converted into a singlet exciter, and the singlet excitation is performed. It is characterized in that the light emitting efficiency of the light emitting element is improved by causing the guest material (fluorescent material) to emit light by emitting light from the child or by transferring energy from the singlet exciter.

Further, in order to efficiently generate TTA in the EL layer, it is important to use a compound having a high proportion of the delayed fluorescence component due to TTA in the light emitting component as the host material. Further, it is important to use a compound having a high excitation energy as a host material, particularly in a light emitting device exhibiting a blue color.

Therefore, one aspect of the present invention is a light emitting element having a pair of electrodes and an EL layer sandwiched between the pair of electrodes. The EL layer has an organic compound, and the organic compound is the first. The luminescence exhibited by the EL layer has a delayed fluorescent component due to triple-term-triple annihilation, and the first triple-term excited state in the organic compound is in the organic compound. The excited state with the lowest excitation energy level, the first triple-term excited state has a molecular orbital in the first skeleton, and the second triple-term excited state in the organic compound is in the second skeleton. Among the triple-term excited states having a molecular orbital and a molecular orbital in the second skeleton, the triple-term excited state has the lowest excitation energy level, and the third triple-term excited state in the organic compound is , Triple-term excited state having the lowest excitation energy level among the triple-term excited states having a molecular orbital in the first skeleton and having a molecular orbital in the first skeleton other than the first triple-term excited state. The energy of the third triple-term excited state, which is a state and has the most stable structure of the third triple-term excited state, is the energy of the first triple-term excited state having the most stable structure of the third triple-term excited state. It is a light emitting element characterized by being higher and lower than the energy of the second triplet excited state having the most stable structure of the third triplet excited state.

Further, another aspect of the present invention is a light emitting element having a pair of electrodes and an EL layer sandwiched between the pair of electrodes. The EL layer has an organic compound, and the organic compound is an organic compound. It has a first skeleton and a second skeleton, and the luminescence exhibited by the EL layer has a delayed fluorescent component due to triple-term-triple annihilation, and the first triple-term excited state in the organic compound is organic. The excited state with the lowest excitation energy level in the compound, the first tripled excited state has a molecular orbital in the first skeleton, and the second triplet excited state in the organic compound is the second. A triple-term excited state having the lowest excitation energy level among the triple-term excited states having a molecular orbital in the skeleton and a molecular orbital in the second skeleton, and a third triple-term excited state in an organic compound. The state is a triple having the lowest excitation energy level among the triple-term excited states having a molecular orbital in the first skeleton and having a molecular orbital in the first skeleton other than the first triple-term excited state. The single-term excited state, which is a term-excited state and has the lowest excitation energy level in the organic compound, is higher than the excitation energy level of the second triple-term excited state and the excitation energy of the third triple-term excited state. It is a light emitting element having an excitation energy level that is equal to or lower than the level.

Further, in the above configuration, the energy of the singlet excited state is higher than the energy of the second triplet excited state having the most stable structure of the third triplet excited state, and the energy of the third triplet excited state is the highest. The energy of the second triplet excited state having the most stable structure of the third triplet excited state, which is equal to or less than the energy of the third triplet excited state having a stable structure, is the energy of the third triplet excited state. It is preferably higher than the energy of the first triplet excited state having the most stable structure.

Further, in the above configuration, the energy conversion value of the absorption edge in the absorption spectrum of the organic compound is higher than the energy of the second triplet excited state having the most stable structure of the third triplet excited state, and the third triplet excited state. The energy of the third triplet excited state having the most stable structure of the triplet excited state is equal to or less than the energy of the third triplet excited state, and the energy of the second triplet excited state having the most stable structure of the third triplet excited state is the third. It is preferable that the energy is higher than that of the first triplet excited state having the most stable structure of the triplet excited state.

Further, in each of the above configurations, it is preferable that the first skeleton has an anthracene skeleton and the second skeleton is bound to the first skeleton.

Further, in each of the above configurations, the emission exhibited by the EL layer preferably has an emission spectrum peak in blue.

Further, in each of the above configurations, it is preferable that the EL layer has a guest material that exhibits fluorescence.

Further, in the above configuration, the light emission exhibited by the guest material preferably has an emission spectrum peak in blue. Further, in the above configuration, the light emission exhibited by the guest material preferably has a delayed fluorescence component. Further, in the above configuration, the guest material preferably has a pyrene skeleton.

Further, another aspect of the present invention is a display device including a light emitting element having each of the above configurations, a color filter, a seal, or a transistor. Another aspect of the present invention is an electronic device having the display device and a housing or a touch sensor. Another aspect of the present invention is a lighting device including a light emitting element having each of the above configurations, a housing, or a touch sensor. Further, one aspect of the present invention includes not only a light emitting device having a light emitting element but also an electronic device having a light emitting device in the category. Therefore, the light emitting device in the present specification refers to an image display device or a light source (including a lighting device). Further, a module in which a connector, for example, an FPC (Flexible Printed Circuit) or a TCP (Tape Carrier Package) is attached to the light emitting device, a module in which a printed wiring board is provided at the tip of the TCP, or a COG (Chip On Glass) in the light emitting element. All modules in which ICs (integrated circuits) are directly mounted by the method are also included in the light emitting device.

According to one aspect of the present invention, it is possible to provide a light emitting device having high luminous efficiency in a light emitting device having a fluorescent compound. Alternatively, according to one aspect of the present invention, it is possible to provide a light emitting element having high luminous efficiency in a light emitting element exhibiting blue color. Alternatively, according to one aspect of the present invention, it is possible to provide a light emitting device having a high proportion of delayed fluorescent components due to TTA among the light emitting components. Alternatively, one aspect of the present invention can provide a light emitting element with reduced power consumption. Alternatively, one aspect of the present invention can provide a novel light emitting device. Alternatively, one aspect of the present invention can provide a novel light emitting device. Alternatively, one aspect of the present invention can provide a novel display device.

The description of these effects does not preclude the existence of other effects. It should be noted that one aspect of the present invention does not necessarily have to have all of these effects. It should be noted that the effects other than these are naturally clarified from the description of the description, drawings, claims, etc., and it is possible to extract the effects other than these from the description of the description, drawings, claims, etc. Is.

A schematic cross-sectional view of the light emitting device according to one aspect of the present invention and a schematic diagram illustrating the correlation of energy levels. The figure explaining the molecular orbital of a compound which concerns on one aspect of this invention. The figure explaining the molecular orbital of a compound which concerns on one aspect of this invention. The figure explaining the molecular orbital of a compound which concerns on one aspect of this invention. The figure explaining the molecular orbital of a compound which concerns on one aspect of this invention. The figure explaining the molecular orbital of a compound which concerns on one aspect of this invention. The figure explaining the energy level of a compound which concerns on one aspect of this invention. The figure explaining the energy level of a compound which concerns on one aspect of this invention. A schematic cross-sectional view of the light emitting device according to one aspect of the present invention and a schematic diagram illustrating the correlation of energy levels. A schematic cross-sectional view of the light emitting device according to one aspect of the present invention and a schematic diagram illustrating the correlation of energy levels. The cross-sectional schematic diagram of the light emitting element of one aspect of this invention. The cross-sectional schematic diagram of the light emitting element of one aspect of this invention. The cross-sectional schematic diagram explaining the manufacturing method of the uniform light emitting element of this invention. The cross-sectional schematic diagram explaining the manufacturing method of the uniform light emitting element of this invention. Top view and schematic cross-sectional view illustrating the display device of one aspect of the present invention. The cross-sectional schematic diagram explaining the display device of one aspect of this invention. The cross-sectional schematic diagram explaining the display device of one aspect of this invention. The cross-sectional schematic diagram explaining the display device of one aspect of this invention. The cross-sectional schematic diagram explaining the display device of one aspect of this invention. The cross-sectional schematic diagram explaining the display device of one aspect of this invention. The cross-sectional schematic diagram explaining the display device of one aspect of this invention. A block diagram and a circuit diagram illustrating a display device according to an aspect of the present invention. The circuit diagram explaining the pixel circuit of the display device of one aspect of this invention. The circuit diagram explaining the pixel circuit of the display device of one aspect of this invention. The perspective view which shows an example of a touch panel. FIG. 5 is a cross-sectional view showing an example of a display device and a touch sensor. FIG. 5 is a cross-sectional view showing an example of a touch panel. A block diagram and a timing chart of the touch sensor. Circuit diagram of the touch sensor. The perspective view explaining the display module. The figure explaining the electronic device. A perspective view and a sectional view illustrating a light emitting device according to an aspect of the present invention. The cross-sectional view explaining the light emitting device of one aspect of this invention. The figure explaining the lighting apparatus and the electronic device of one aspect of this invention. The figure explaining the lighting apparatus of one aspect of this invention. The figure explaining the fluorescence lifetime characteristic of the light emitting element which concerns on Example 1. FIG. The figure explaining the current efficiency-luminance characteristic of a light emitting element which concerns on Example 1. FIG. The figure explaining the external quantum efficiency-luminance characteristic of a light emitting element which concerns on Example 1. FIG. The figure explaining the luminance-voltage characteristic of a light emitting element which concerns on Example 1. FIG. The figure explaining the electroluminescence spectrum of the light emitting element which concerns on Example 1. FIG. The figure explaining the current efficiency-luminance characteristic of a light emitting element which concerns on Example 2. FIG. The figure explaining the external quantum efficiency-luminance characteristic of a light emitting element which concerns on Example 2. FIG. The figure explaining the luminance-voltage characteristic of a light emitting element which concerns on Example 2. FIG. The figure explaining the electroluminescence spectrum of the light emitting element which concerns on Example 2. FIG. The figure explaining the light emitting angle distribution of the light emitting element which concerns on Example 2. FIG. The figure explaining the reliability test result of the light emitting element which concerns on Example 2. FIG. The cross-sectional schematic diagram explaining the light emitting element which concerns on Example 3. FIG. The figure explaining the current efficiency-luminance characteristic of a light emitting element which concerns on Example 3. FIG. The figure explaining the current efficiency-luminance characteristic of a light emitting element which concerns on Example 3. FIG. The figure explaining the luminance-voltage characteristic of a light emitting element which concerns on Example 3. FIG. The figure explaining the luminance-voltage characteristic of a light emitting element which concerns on Example 3. FIG. The figure explaining the electroluminescence spectrum of the light emitting element which concerns on Example 3. FIG. The figure explaining the electroluminescence spectrum of the light emitting element which concerns on Example 3. FIG. The figure explaining the electroluminescence spectrum of the light emitting element which concerns on Example 3. FIG. The figure explaining the electroluminescence spectrum of the light emitting element which concerns on Example 3. FIG. The figure explaining the chromaticity angle dependence of a light emitting element which concerns on Example 3. FIG. The figure explaining the reliability test result of the light emitting element which concerns on Example 3. FIG. The figure explaining the reliability test result of the light emitting element which concerns on Example 3. FIG. The figure explaining the reliability test result of the light emitting element which concerns on Example 3. FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and its form and details can be variously changed without departing from the gist and scope of the present invention. Therefore, the present invention is not construed as being limited to the description of the embodiments shown below.

The positions, sizes, ranges, etc. of each configuration shown in the drawings and the like may not represent the actual positions, sizes, ranges, etc. for the sake of easy understanding. Therefore, the disclosed invention is not necessarily limited to the position, size, range, etc. disclosed in the drawings and the like.

Further, in the present specification and the like, the ordinal numbers attached as the first, second and the like are used for convenience, and may not indicate the process order or the stacking order. Therefore, for example, the "first" can be appropriately replaced with the "second" or "third" for explanation. In addition, the ordinal numbers described in the present specification and the like may not match the ordinal numbers used to specify one aspect of the present invention.

Further, in the present specification and the like, when explaining the structure of the invention using drawings, reference numerals indicating the same thing may be commonly used between different drawings.

Further, in the present specification and the like, the term "membrane" and the term "layer" can be interchanged with each other. For example, it may be possible to change the term "conductive layer" to the term "conductive layer". Alternatively, for example, it may be possible to change the term "insulating film" to the term "insulating layer".

Further, in the present specification and the like, the singlet excited state (S ^* ) is a singlet state having excitation energy. Among the singlet excited states, the excited state having the lowest energy is called the lowest singlet excited state. The singlet excitation energy level is the excitation energy level in the singlet excited state. Among the singlet excitation energy levels, the lowest excitation energy level is called the lowest singlet excitation energy (S1) level.

Further, in the present specification and the like, the triplet excited state (T ^* ) is a triplet state having excitation energy. Among the triplet excited states, the excited state having the lowest energy is called the lowest triplet excited state. A triplet excited state having higher energy than the lowest triplet excited state is called a high triplet excited state. The triplet excitation energy level is the excitation energy level in the triplet excited state. Among the triplet excitation energy levels, the lowest excitation energy level is called the lowest triplet excitation energy (T1) level. An energy level higher than the lowest triplet excitation energy level is called a high triplet excitation energy level.

Further, in the present specification and the like, the fluorescent material is a material that gives light to the visible light region when relaxing from the singlet excited state to the ground state. The phosphorescent material is a material that gives light to the visible light region at room temperature when relaxing from the triplet excited state to the ground state. In other words, the phosphorescent material is one of the materials capable of converting triplet excitation energy into visible light.

In the present specification and the like, room temperature means any temperature of 0 ° C. to 40 ° C.

Further, in the present specification and the like, the blue wavelength region is a wavelength region of 400 nm or more and 550 nm or less, and blue light emission is light emission having at least one emission spectrum peak in the region.

(Embodiment 1)
In the present embodiment, the light emitting device of one aspect of the present invention will be described below with reference to FIGS. 1 to 8.

<Structure example of light emitting element>
First, the configuration of the light emitting device according to one aspect of the present invention will be described below with reference to FIGS. 1A, 1B and 1C.

FIG. 1A is a schematic cross-sectional view of a light emitting device 120 according to an aspect of the present invention.

The light emitting element 120 has a pair of electrodes (electrode 101 and electrode 102), and has an EL layer 100 provided between the pair of electrodes. The EL layer 100 has at least a light emitting layer 130.

Further, the EL layer 100 shown in FIG. 1A has a functional layer in addition to the light emitting layer 130. The functional layer includes a hole injection layer 111, a hole transport layer 112, an electron transport layer 118, and an electron injection layer 119.

In the present embodiment, of the pair of electrodes, the electrode 101 is used as an anode and the electrode 102 is used as a cathode, but the configuration of the light emitting element 120 is not limited to this. That is, the electrode 101 may be used as a cathode, the electrode 102 may be used as an anode, and the layers may be laminated in the reverse order. That is, the hole injection layer 111, the hole transport layer 112, the light emitting layer 130, the electron transport layer 118, and the electron injection layer 119 may be stacked from the anode side.

The configuration of the EL layer 100 is not limited to the configuration shown in FIG. 1 (A), and is selected from the hole injection layer 111, the hole transport layer 112, the electron transport layer 118, and the electron injection layer 119. It may be configured to have at least one. Alternatively, the EL layer 100 reduces the hole or electron injection barrier, improves the hole or electron transportability, inhibits the hole or electron transportability, or suppresses the quenching phenomenon by the electrode. It may be configured to have a functional layer having a function such as being able to perform. The light emitting layer 130 or the functional layer may be a single layer or a plurality of layers may be laminated.

FIG. 1B is a schematic cross-sectional view showing an example of the light emitting layer 130 shown in FIG. 1A. The light emitting layer 130 shown in FIG. 1 (B) has a host material 131 and a guest material 132.

The host material 131 preferably has a function of converting triplet excitation energy into singlet excitation energy by TTA. By doing so, a part of the triplet excitation energy generated in the light emitting layer 130 can be converted into singlet excitation energy by TTA in the host material 131 and transferred to the guest material 132, so that it can be taken out as fluorescence emission. It becomes. For that purpose, the minimum singlet excitation energy (S1) level of the host material 131 is preferably higher than the S1 level of the guest material 132. Further, the minimum triplet excitation energy (T1) level of the host material 131 is preferably lower than the T1 level of the guest material 132.

The host material 131 may be composed of a single compound or may be composed of a plurality of compounds. Further, as the guest material 132, a luminescent organic compound may be used, and it is preferable that the luminescent organic compound is a substance capable of emitting fluorescence (hereinafter, also referred to as a fluorescent material). In the following description, a configuration using a fluorescent material as the guest material 132 will be described. The guest material 132 may be read as a fluorescent material.

<Light emitting mechanism of light emitting element>
First, the light emitting mechanism of the light emitting element 120 will be described below.

In the light emitting device 120 of one aspect of the present invention, by applying a voltage between a pair of electrodes (electrode 101 and electrode 102), electrons from the cathode and holes (holes) from the anode are respectively sent to the EL layer 100. It is injected and current flows. Then, excitons are formed by recombination of the injected electrons and holes. Among the excitons generated by carrier recombination, the ratio of singlet excitons to triplet excitons (hereinafter referred to as exciton generation probability) is 1: 3 according to statistical probabilities.

The singlet excitons are generated in the EL layer 100 by the following two processes, and light emission from the guest material 132 is obtained.
(Α) Direct production process (β) TTA process

<(α) Direct generation process>
First, a case where carriers (electrons and holes) are recombined in the light emitting layer 130 included in the EL layer 100 to form singlet excitons will be described.

The exciton is a carrier (electron and hole) pair. Since excitons have energy, the material in which excitons are generated is in an excited state.

When carriers are recombined in the host material 131, the excited state (singlet or triplet excited state) of the host material 131 is formed by the generation of excitons. At this time, when the excited state of the host material 131 is the singlet excited state, the singlet excitation energy is transferred from the S1 level of the host material 131 to the S1 level of the guest material 132, and the singlet of the guest material 132 is singlet. A term excited state is formed. When the excited state of the host material 131 is the triplet excited state, it will be described in the (β) TTA process described later.

Further, when the carriers are recombined in the guest material 132, the excited state (singlet excited state or triplet excited state) of the guest material 132 is formed by the generation of excitons.

When the excited state of the formed guest material 132 is the singlet excited state, light emission is obtained from the singlet excited state of the guest material 132. At this time, in order to obtain high luminous efficiency, the fluorescence quantum yield of the guest material 132 is preferably high. Specifically, the fluorescence quantum yield of the guest material 132 is preferably 50% or more, more preferably 70% or more, still more preferably 90% or more.

On the other hand, when the triplet excited state of the guest material 132 is formed, the triplet excited state of the guest material 132 is heat deactivated and does not contribute to light emission. However, when the T1 level of the host material 131 is lower than the T1 level of the guest material 132, the triplet excitation energy of the guest material 132 goes from the T1 level of the guest material 132 to the T1 level of the host material 131. It becomes possible to transfer energy. In that case, the conversion from triplet excitation energy to singlet excitation energy becomes possible by the (β) TTA process described later.

<(Β) TTA process>
Next, a case where singlet excitons are formed by triplet excitons formed in the carrier recombination process in the light emitting layer 130 will be described.

Here, the case where the T1 level of the host material 131 is lower than the T1 level of the guest material 132 will be described. A schematic diagram showing the correlation of energy levels at this time is shown in FIG. 1 (C). The notation and reference numerals in FIG. 1C are as follows. The T1 level of the host material 131 may be higher than the T1 level of the guest material 132.
-Host (131): Host material 131
-Guest (132): Guest material 132 (fluorescent material)
・ S _FH : S1 level of host material 131 ・ T _FH : T1 level of host material 131 ・ S _FG : S1 level of guest material 132 (fluorescent material) ・ T _FG : T1 of guest material 132 (fluorescent material) Level

The carriers recombine in the host material 131, and the generation of excitons forms an excited state of the host material 131. At this time, when the generated excited element is a triplet excited element, a part of the triplet excited energy is converted into the singlet excited energy by the proximity of the two generated triplet excited elements. A singlet excited state of the host material 131 occurs (see TTA in FIG. 1C). This is represented by the following general formula (G1).

³ H + ³ H → ¹ H ^* + ¹ H (G1)
³ H + ³ H → ³ H ^* + ¹ H (G2)

The general formula (G1) is a reaction in which a singlet exciton ( ¹ H ^* ) is generated from two triplet excitons ( ³ H) in the host material 131. In general formula (G2), in a host material 131, two triplet excitons ^{(3 H),} are electronically or vibrationally excited triplet excitons ^{(3 H *)} is produced reaction .. In the general formulas (G1) and (G2), ¹ H represents the singlet ground state in the host material 131.

When the density of triplet excitons in the light emitting layer 130 is sufficiently high (1 × 10 ^-12 cm ^-3 or more), the deactivation of the triplet excitons alone is ignored, and two adjacent triplet excitons are ignored. Only the reaction by can be considered.

In general formula (G2) triplet excitons ^{(3 H *)} which is electronically or vibrationally excited formed in, by the intersection between the immediately internal conversion or claim, triplet excitons ^{(3 H)} or Converted to singlet excitons ( ¹ H ^* ). Thus, in the general formula (G2), when all of the electronic or vibrational excited triplet excitons ^{(3 H *)} is converted to singlet excitons ^{(1 H *),} 2 triple A maximum of one singlet exciton ( ¹ H ^* ) will be generated from the term exciton ( ³ H).

On the other hand, the statistical generation ratio of triplet excitons ^{(3 H)} singlet excitons generated directly by recombination of carriers injected from a pair of electrodes ^{(1 H *), 1 H} *: 3 H = It is 1: 3. That is, the probability that singlet excitons are directly generated by the recombination of carriers injected from a pair of electrodes is 25%.

Therefore, by combining the singlet excitons directly generated by the recombination of the carriers injected from the pair of electrodes and the singlet excitons generated by the TTA, the singlet excitons injected from the pair of electrodes are directly generated by the recombination. Five singlet excitons can be generated from the generated eight excitons (total of singlet excitons and triplet excitons) (general formula (G3)). That is, TTA makes it possible to improve the singlet exciton generation probability from the conventional 25% to a maximum of 62.5%.

2 ¹ H ^* + 6 ³ H → 2 ¹ H ^* + (3 ¹ H ^* + 3 ¹ H) (G3)

In the singlet excited state of the host material 131 formed by the singlet excitators generated by the above process, the guest material 132 has a lower excitation energy level than the S1 level ( _SFH ) of the host material 131. Energy transfer to the S1 level ( _SFG ) occurs (see FIG. 1 (C) Route A). Then, the guest material 132 in the singlet excited state fluoresces.

When the excited state formed by the exciton generated by the recombination of carriers in the guest material 132 is the triplet excited state, the T1 level ( _TFH ) of the host material 131 is the T1 level ( _TFH ) of the guest material. If it is lower than T _FG ), T _FG transfers energy to _TFH without deactivation (see Route B in FIG. 1 (C)) and is used for TTA.

Further, when the T1 level (T _FG ) of the guest material 132 is lower than the T1 level ( _TFH ) of the host material 131, the weight ratio between the host material 131 and the guest material 132 is the weight of the guest material 132. The lower the ratio, the better. Specifically, the weight ratio of the guest material 132 to 1 for the host material 131 is preferably greater than 0 and 0.05 or less. By doing so, the probability of carrier recombination in the guest material 132 can be reduced. Further, it is possible to reduce the probability that energy transfer occurs in the T1 level position of the host material 131 from _{(T FH)} T1 level position of the guest material 132 to _{(T FG).}

As described above, since the triplet excitons formed in the light emitting layer 130 are converted into singlet excitons by TTA, it is possible to efficiently obtain light emission from the guest material 132.

<About TTA efficiency>
As described above, TTA makes it possible to improve the generation probability of singlet excitons and improve the luminous efficiency of the light emitting element. However, in order to obtain high luminous efficiency, the probability of TTA occurring (TTA efficiency). It is important to increase (also called). That is, it is important that the ratio of the delayed fluorescent component due to TTA to the light emitted by the light emitting element is high.

In order to increase the probability that TTA occurs, it is preferable that the host material 131 has a higher energy in the singlet excited state and a lower energy in the triplet excited state than the guest material 132. As such a compound, the host material 131 preferably has a condensed aromatic ring skeleton, and more preferably has an acene skeleton such as an anthracene skeleton or a tetracene skeleton.

Further, in a light emitting device that emits blue light, it is necessary to use a compound having a large excitation energy as the host material 131. That is, as a compound that can be used as a light emitting material or a host material 131 in a light emitting element exhibiting blue light emission and exhibits delayed fluorescence by TTA, a compound having an anthracene skeleton is preferable. Among them, in order to obtain high luminous efficiency, a compound having an anthracene skeleton and exhibiting high TTA efficiency is preferable.

When holes are injected into the EL layer from the anode and electrons are injected from the cathode into the EL layer and an electric current flows, the holes and electrons are the highest occupied molecular orbitals of the compound possessed by the EL layer (also referred to as Highest Occupied Molecular Orbital or HOMO). And the lowest empty orbital (also called Holest Unoccuped Molecular Orbital, LUMO) is injected and transported.

When the injected holes and electrons are recombined in the host material, when the HOMO orbital and the LUMO orbital in the host material have molecular orbitals in the same region, it corresponds to the energy gap between the HOMO level and the LUMO level. Excitons with energy are generated.

When the injected holes and electrons are recombined in the host material and the HOMO orbital and the LUMO orbital in the host material have molecular orbitals in different regions, the LUMO + n orbital (the molecular orbital is in the same region as the HOMO orbital). Excitons with energies higher than the LUMO orbitals, where n is a natural number) and HOMO orbitals with energy corresponding to the energy gap are generated, or molecules in the same region as the HOMO-n'orbitals. An exciton having an orbital and lower energy than the HOMO orbital, where n'is a natural number) and an energy gap corresponding to the energy gap between the LUMO orbital is generated.

The energy corresponding to the energy gap in the host material corresponds to the energy in the at least singlet excited state. Therefore, the singlet excited state of the host material formed by carrier recombination is at least the singlet excited state.

Similarly, the triplet excited state of the host material formed by carrier recombination is the first triplet excited state having a molecular orbital in the same region as the at least singlet excited state. The first triplet excited state is the lowest triplet excited state.

The molecular orbital represents a region in a compound in which an electron is likely to be found, or the probability of finding an electron. Molecular orbitals make it possible to describe in detail the electron configuration (spatial distribution and energy of electrons) of a molecule.

The second triplet excited state and the third triplet excited state of the host material are high triplet excited states (triple excited states having higher energy than the first triplet excited state) and the second triplet. The term excited state is a tripled excited state having the lowest excitation energy among the high triplet excited states having molecular orbitals in a region different from the first triplet excited state, and the third triplet excited state is the first triplet excited state. It is assumed that the triple-term excited state has the lowest excitation energy among the high-triple excited states having molecular orbitals in the same region as the triple-term excited state. When a high triplet excited state is generated by TTA, it is in the same region as the first triplet excited state rather than the second triplet excited state having a molecular orbital in a region different from the first triplet excited state. A third triplet excited state with a molecular orbital is more likely to be formed. This is because TTA is a reaction that arises from the first triplet excited state, which is the lowest triplet excited state. Even if the formed third triplet excited state is further vibrationally excited, the third triplet excited state having the most energy-stable vibration state can be obtained by rapidly relaxing the vibration. Can be formed.

The three-dimensional structure in which the energy is most stable in the ground state of the compound (hereinafter, the most stable structure) and the most stable structure in the excited state (singlet excited state and triplet excited state) have different three-dimensional structures. Further, the most stable structures in different excited states have different three-dimensional structures. Further, when the compound is in the electronic state of the ground state or the excited state (singlet excited state or triplet excited state) and further has vibration energy or rotational energy, it is in the vibrationally excited or rotationally excited state. When a compound is vibrationally excited in a certain electronic state, it has a structure different from that of the state in which the energy is most stable in the electronic state, even if the molecular structure is the same. For example, the most stable structure in the first triplet excited state (the three-dimensional structure in the most energy-stable state) and the most stable structure in the third triplet excited state are different structures. Further, the structure of the first triplet excited state, which is in the state of being oscillated in the first triplet excited state and has the most stable structure of the third triplet excited state, is in the first triplet excited state. The structure is different from the most stable structure. In other words, if a compound has a different three-dimensional structure in a certain electronic state, it will have a different energy.

In one aspect of the present invention, the energy of the third triplet excited state having the most stable structure of the third triplet excited state is the energy of the second triplet having the most stable structure of the third triplet excited state. It is preferably lower than the excited state energy. By doing so, internal conversion from the third triplet excited state having the most stable structure to the second triplet excited state is less likely to occur. The third triplet excited state has a molecular orbital in the same region as the first triplet excited state, and the first triplet excited state has a molecular orbital in the same region as the at least singlet excited state. .. That is, the third triplet excited state has a molecular orbital in the same region as the at least singlet excited state. Therefore, there is a high probability that intersystem crossing and energy transfer from the formed triplet excited state to the lowest singlet excited state will occur. That is, it is preferable because the probability that a singlet excited state is generated by TTA increases. At this time, the energy of the third triplet excited state having the most stable structure of the third triplet excited state is the energy of the second triplet excited state having the most stable structure of the third triplet excited state. It is preferably 0.1 eV or more lower than the energy, and more preferably 0.2 eV or more lower than the energy.

On the other hand, the energy of the third triplet excited state having the most stable structure of the third triplet excited state is equal to or higher than the energy of the second triplet excited state having the most stable structure of the third triplet excited state. In some cases, the formed third triplet excited state is likely to transition to the second triplet excited state by internal conversion. The second triplet excited state has a molecular orbital in a region different from that of the first triplet excited state, and the first triplet excited state has a molecular orbital in the same region as the at least singlet excited state. .. That is, the second triplet excited state has a molecular orbital in a region different from that of the lowest singlet excited state. Therefore, the probability of intersystem crossing and energy transfer from the second triplet excited state to the lowest singlet excited state is low. That is, the probability that a singlet excited state is generated by TTA is low.

Since the third triplet excited state has a molecular orbital in the same region as the lowest singlet excited state, the energy of the third triplet excited state having the most stable structure of the third triplet excited state is The energy of the minimum singlet excited state is higher than the energy of the second triplet excited state even when the energy of the second triplet excited state having the most stable structure of the third triplet excited state is higher than that of the energy of the second triplet excited state. Moreover, it is preferably equal to or less than the energy of the third triplet excited state. More preferably, the energy of the lowest singlet excited state is higher than the energy of the second triplet excited state having the most stable structure of the third triplet excited state, and the most stable structure of the third triplet excited state. Is less than or equal to the energy of the third triplet excited state having. Doing so increases the probability of intersystem crossing and energy transfer from the formed third triplet excited state to the lowest singlet excited state. That is, it is preferable because the probability that a singlet excited state is generated by TTA increases. At this time, the energy of the third triplet excited state having the most stable structure of the third triplet excited state is the energy of the second triplet excited state having the most stable structure of the third triplet excited state. It is preferably 0.1 eV or more higher than the energy, and more preferably 0.2 eV or more higher than the energy.

In order to efficiently generate TTA, it is preferable that the energy difference between the lowest singlet excitation energy level and the lowest triplet excitation energy level is 0.5 eV or more in the organic compound in which TTA is generated. Further, the minimum singlet excitation energy level is preferably energy equal to or less than twice the minimum triplet excitation energy level.

The minimum singlet excitation energy level can be observed from the absorption spectrum when the organic compound transitions from the singlet ground state to the minimum singlet excited state. Alternatively, the minimum singlet excitation energy level may be estimated from the peak wavelength of the fluorescence emission spectrum of the organic compound. In addition, the lowest triplet excitation energy level can be observed from the absorption spectrum when the organic compound transitions from the singlet ground state to the lowest triplet excited state, but since the transition is forbidden, it is observed. Can be difficult. In that case, the lowest triplet excitation energy level may be estimated from the phosphorescent spectrum peak wavelength of the organic compound.

Therefore, it is preferable that the energy conversion value difference between the peak wavelength of the fluorescence emission spectrum and the peak wavelength of the phosphorescence emission spectrum in the organic compound contained in the light emitting element of one aspect of the present invention is 0.5 eV or more.

<Calculation of molecular orbital by quantum chemistry calculation>
Next, for a compound that can be used in one aspect of the present invention, an example in which the molecular orbital is calculated by quantum chemistry calculation and the triplet excitation energy level is calculated will be shown. The structure and abbreviation of the compound used in the calculation are shown below.

The calculation method is as follows. Gaussian09 was used as the quantum chemistry calculation program. The calculation was performed using a high performance computer (ICE X manufactured by SGI).

First, the most stable structure in the singlet ground state was calculated by the density functional theory (DFT). 6-311G (d, p) was used as the basis function. CAM-B3LYP was used as the functional. Next, the time-dependent density functional theory (TD-DFT) was used to calculate the distribution of energy and molecular orbitals involved in the transition from the most stable structure of the singlet ground state to the triplet excited state. The total energy of DFT is represented by the sum of potential energy, electron-electron electrostatic energy, electron kinetic energy, and exchange correlation energy including all complex electron-electron interactions. In DFT, the calculation is highly accurate because the exchange correlation interaction is approximated by a functional of one-electron potential expressed by electron density (meaning a function of a function).

Among the molecular orbitals involved in the transition from the singlet ground state to the triplet excited state, the distribution of molecular orbitals with a large contribution is shown in FIGS. 2 to 6.

As shown in FIGS. 2 (A) to 2 (C), in 9- [4- (10-phenyl-9-anthril) phenyl] -9H-carbazole (abbreviation: CzPA), the singlet ground state to the triplet excited state The transition to 151 is a transition between the HOMO orbital and the LUMO orbital, each of which has a molecular orbital in the anthracene skeleton. The transition from the singlet ground state to the triplet excited state 152 is a transition between the HOMO-2 orbital and the LUMO + 1 orbital, and the molecular orbital is attached to the substituent (here, the phenylcarbazole skeleton) that binds to the anthracene skeleton. have. The transition from the singlet ground state to the triplet excited state 153 is a transition between the HOMO orbital and the LUMO + 8 orbital, and a transition between the HOMO-5 orbital and the LUMO orbital, and the molecular orbitals in the anthracene skeleton, respectively. have. Therefore, the triplet excited state 151 has a molecular orbital in the anthracene skeleton, the triplet excited state 152 has a molecular orbital in the substituent that binds to the anthracene skeleton, and the triplet excited state 153 has a molecular orbital in the anthracene skeleton. It is a triplet excited state. The HOMO-2 orbit and the HOMO-5 orbit represent the second and fifth orbits having lower energies than the HOMO orbit, and the LUMO + 1 and LUMO + 8 orbits represent the first and fifth orbits having higher energy than the LUMO orbit. Represents the eighth orbit. The energy involved in the transition from the singlet ground state to the triplet excited state increases in the order of triplet excited states 151, 152, and 153, and triplet excited state 151 is the lowest triplet excited state in CzPA.

Further, as shown in FIGS. 3A to 3D, triplet excitation from the singlet ground state is performed in 2-tert-butyl-9,10-di (2-naphthyl) anthracene (abbreviation: t-BuDNA). The transition to state 161 is a transition between the HOMO orbital and the LUMO orbital, each of which has a molecular orbital in the anthracene skeleton. The transition from the singlet ground state to the triplet excited state 162 is a transition between the HOMO-1 orbital and the LUMO + 2 orbital, and the molecular orbital is assigned to the substituent (here, the naphthalene skeleton) that binds to the anthracene skeleton. Have. The transition from the singlet ground state to the triplet excited state 163 is the transition between the HOMO-2 orbital and the LUMO + 1 orbital, and the molecular orbital is assigned to the substituent (here, the naphthalene skeleton) that binds to the anthracene skeleton. Have. The transition from the singlet ground state to the triplet excited state 164 is a transition between the HOMO-6 orbital and the LUMO orbital, and a transition between the HOMO orbital and the LUMO + 6 orbital, and the molecular orbitals in the anthracene skeleton, respectively. have. Therefore, the triplet excited state 161 has a molecular orbital in the anthracene skeleton, the triplet excited states 162 and 163 have a molecular orbital in the substituent that binds to the anthracene skeleton, and the triplet excited state 164 has a molecular orbital in the anthracene skeleton. It is a triplet excited state having. The HOMO-1 orbit, the HOMO-2 orbit, and the HOMO-6 orbit represent the first, second, and sixth orbits having lower energies than the HOMO orbit, and are the LUMO + 1 orbit, the LUMO + 2 orbit, and the LUMO + 6 orbit. Represents the first, second and sixth orbitals with higher energy than the LUMO orbitals. The energy involved in the transition from the singlet ground state to the triplet excited state increases in the order of triplet excited states 161, 162, 163, and 164, and triplet excited state 161 is the lowest triplet excited state in t-BuDNA. is there.

Further, as shown in FIGS. 4 (A) to 4 (D), in 7- [4- (10-phenyl-9-anthril) phenyl] -7H-dibenzo [c, g] carbazole (abbreviation: cgDBCzPA), a single layer. The transition from the ground state to the triplet excited state 171 is a transition between the HOMO-1 orbital and the LUMO orbital, each of which has a molecular orbital in the anthracene skeleton. The transition from the singlet ground state to the triplet excited state 172 is the transition between the HOMO orbital and the LUMO + 1 orbital, and the molecular orbital is assigned to the substituent (here, the phenyldibenzocarbazole skeleton) that binds to the anthracene skeleton. Have. Further, the transition from the singlet ground state to the triplet excited state 173 is a transition between the HOMO orbital and the LUMO + 3 orbital, and a transition between the HOMO-3 orbital and the LUMO + 1 orbital, which are combined with the anthracene skeleton, respectively. It has a molecular orbital at the substituent (here, the phenyldibenzocarbazole skeleton). The transition from the singlet ground state to the triplet excited state 174 is a transition between the HOMO-1 orbital and the LUMO + 10 orbital and a transition between the HOMO-7 orbital and the LUMO orbital, respectively, in the anthracene skeleton. It has a molecular orbital. Therefore, the triplet excited state 171 has a molecular orbital in the anthracene skeleton, the triplet excited states 172 and 173 have a molecular orbital in the substituent that binds to the anthracene skeleton, and the triplet excited state 174 has a molecular orbital in the anthracene skeleton. It is a triplet excited state having. The HOMO-1 orbit, HOMO-3 orbit, and HOMO-7 orbit represent the first, third, and seventh orbits having lower energies than the HOMO orbit, and are LUMO + 1, LUMO + 3 and LUMO + 10 orbits. Represents the first, third and tenth orbitals having higher energy than the LUMO orbitals. The energy involved in the transition from the singlet ground state to the triplet excited state increases in the order of triplet excited states 171, 172, 173, and 174, and triplet excited state 171 is the lowest triplet excited state in cgDBCzPA.

Further, as shown in FIGS. 5 (A) to 5 (D), in 9- (2-naphthyl) -10- [4- (1-naphthyl) phenyl] anthracene (abbreviation: BH-1), the singlet ground state. The transition from the triplet excited state 181 to the triplet excited state 181 is a transition between the HOMO orbital and the LUMO orbital, each of which has a molecular orbital in the anthracene skeleton. The transition from the singlet ground state to the triplet excited state 182 is the transition between the HOMO-1 orbital and the LUMO + 1 orbital, and the molecular orbitals are attached to the substituents (here, the phenylnaphthalene skeleton) that bind to the anthracene skeleton. have. The transition from the singlet ground state to the triplet excited state 183 is the transition between the HOMO-2 orbital and the LUMO + 2 orbital, and the molecular orbital is assigned to the substituent (here, the naphthalene skeleton) that binds to the anthracene skeleton. Have. The transition from the singlet ground state to the triplet excited state 184 is a transition between the HOMO orbital and the LUMO + 8 orbital, and a transition between the HOMO-7 orbital and the LUMO orbital, and the molecular orbitals in the anthracene skeleton, respectively. have. Therefore, the triplet excited state 181 has a molecular orbital in the anthracene skeleton, the triplet excited states 182 and 183 have a molecular orbital in the substituent that binds to the anthracene skeleton, and the triplet excited state 184 has a molecular orbital in the anthracene skeleton. It is a triplet excited state having. The HOMO-1 orbit, HOMO-2 orbit, and HOMO-7 orbit represent the first, second, and seventh orbits having lower energies than the HOMO orbit, and are LUMO + 1, LUMO + 2 and LUMO + 8 orbits. Represents the first, second and eighth orbitals having higher energy than the LUMO orbitals. The energy involved in the transition from the singlet ground state to the triplet excited state increases in the order of triplet excited states 181, 182, 183, and 184, and triplet excited state 181 is the lowest triplet excited state in BH-1. is there.

Further, as shown in FIGS. 6 (A) to 6 (D), in 9- (1-naphthyl) -10- (2-naphthyl) anthracene (abbreviation: α, β-ADN), from the singlet ground state to the triplet. The transition to the excited state 191 is a transition between the HOMO orbital and the LUMO orbital, each of which has a molecular orbital in the anthracene skeleton. The transition from the singlet ground state to the triplet excited state 192 is the transition between the HOMO-1 orbital and the LUMO + 2 orbital, and each has a molecular orbital on a substituent (here, a naphthalene skeleton) that binds to the anthracene skeleton. Have. The transition from the singlet ground state to the triplet excited state 193 is the transition between the HOMO-2 orbital and the LUMO + 1 orbital, and the molecular orbital is assigned to the substituent (here, the naphthalene skeleton) that binds to the anthracene skeleton. Have. The transition from the singlet ground state to the triplet excited state 194 is a transition between the HOMO-6 orbital and the LUMO orbital, and a transition between the HOMO orbital and the LUMO + 6 orbital, and the molecular orbitals in the anthracene skeleton, respectively. have. Therefore, the triplet excited state 191 has a molecular orbital in the anthracene skeleton, the triplet excited states 192 and 193 have a molecular orbital in the substituent that binds to the anthracene skeleton, and the triplet excited state 194 has a molecular orbital in the anthracene skeleton. It is a triplet excited state having. The HOMO-1 orbit, the HOMO-2 orbit, and the HOMO-6 orbit represent the first, second, and sixth orbits having lower energies than the HOMO orbit, and are the LUMO + 1 orbit, the LUMO + 2 orbit, and the LUMO + 6 orbit. Represents the first, second and sixth orbitals with higher energy than the LUMO orbitals. The energy involved in the transition from the singlet ground state to the triplet excited state increases in the order of triplet excited states 191, 192, 193, and 194, and triplet excited state 191 has the lowest triplet excitation in α and β-ADN. It is in a state.

Next, in each compound, the triplet excited state (triple) having the lowest excitation energy among the high triplet excited states (triplet excited states having higher excitation energies than the lowest triplet excited state) having a molecular orbital in the anthracene skeleton. The most stable structure in the term excited states 153, 164, 174, 184, 194) was calculated by the time-dependent density functional theory (TD-DFT). 6-311G (d, p) was used as the basis function. Moreover, CAM-B3LYP was used as a functional. Further, the energy of the highly triplet excited state having the most stable structure of the triplet excited state was calculated based on the energy of the most stable structure of the singlet ground state. Here, the lowest triplet excited state is the first triplet excited state (triplet excited state 151, 161, 171, 181, 191). Further, the triplet excited state having the lowest excitation energy among the triplet excited states having a molecular orbital at the substituent binding to the anthracene skeleton and having a molecular orbital at the substituent binding to the anthracene skeleton is the second triplet. It is a term excited state (triplet excited state 152, 162, 172, 182, 192). Further, the triplet excitation having the lowest excitation energy among the triplet excited states having a molecular orbital in the anthracene skeleton and having a molecular orbital in the anthracene skeleton other than the first triplet excited state (minimum triplet excited state). The state is the third triplet excited state (triplet excited state 153, 164, 174, 184, 194).

The excitation energy levels of the second triplet excited state and the third triplet excited state having the most stable structure of the third triplet excited state in each compound estimated as described above are shown in FIGS. 7 and 8. , And Table 1. Since the above calculation method tends to underestimate the triplet excitation energy level, the calculated value is corrected to 1.066 times.

In CzPA and t-BuDNA, the energy of the third triplet excited state having the most stable structure of the third triplet excited state is the energy of the second triplet having the most stable structure of the third triplet excited state. It is lower than the excited state energy. Therefore, internal conversion from the third triplet excited state having the most stable structure to the second triplet excited state is unlikely to occur. Further, the third triplet excited state has a molecular orbital in the same region as the first triplet excited state, and the first triplet excited state has a molecular orbital in the same region as the at least singlet excited state. That is, the third triplet excited state has a molecular orbital in the same region as the at least singlet excited state. Therefore, there is a high probability that intersystem crossing and energy transfer will occur from the formed third triplet excited state to the lowest singlet excited state. That is, it is preferable because the probability that a singlet excited state is generated by TTA increases.

On the other hand, in BH-1 and α, β-ADN, the energy of the third triplet excited state having the most stable structure of the third triplet excited state has the most stable structure of the third triplet excited state. It is equal to or higher than the energy of the second triplet excited state. Therefore, the formed third triplet excited state is likely to rapidly transition to the second triplet excited state by internal conversion. The second triplet excited state has a molecular orbital in a region different from that of the first triplet excited state, and the first triplet excited state has a molecular orbital in the same region as the at least singlet excited state. That is, the second triplet excited state has a molecular orbital in a region different from that of the lowest singlet excited state. Therefore, the probability of intersystem crossing and energy transfer from the second triplet excited state to the lowest singlet excited state is low. That is, the probability that a singlet excited state is generated by TTA is low.

In cgDBCzPA, the energy of the third triplet excited state having the most stable structure of the third triplet excited state is the energy of the second triplet excited state having the most stable structure of the third triplet excited state. Is more than the energy of. Further, the difference in energy is 0.2 eV or more. Further, as will be described later, the minimum singlet excitation energy level calculated from the measurement of the absorption spectrum of cgDBCzPA is 2.95 eV. Therefore, in cgDBCzPA, the energy of the lowest singlet excited state is higher than the energy of the second triplet excited state and equal to or less than the energy of the third triplet excited state, or the energy of the lowest singlet excited state is , Higher than the energy of the second triplet excited state having the most stable structure of the third triplet excited state, and the energy of the third triplet excited state having the most stable structure of the third triplet excited state It is as follows. As described above, since the third triplet excited state has a molecular orbital in the same region as the lowest singlet excited state, the intersystem crossing from the formed third triplet excited state to the lowest singlet excited state. And the probability that energy transfer will occur is high. That is, it is preferable because the probability that a singlet excited state is generated by TTA increases.

As will be described later, the lowest triplet excitation energy levels calculated from the phosphorescence spectrum measurements of CzPA, t-BuDNA, and cgDBCzPA at a low temperature (10K) are 1.72 eV, 1.70 eV, and 1.72 eV, respectively. Is. Therefore, the second triplet excited state having the most stable structure of the third triplet excited state and the third triplet excited state having the most stable structure of the third triplet excited state in the compound are respectively. It is a triplet excited state having higher energy than the first triplet excited state (minimum triplet excited state).

<Material>
Next, the details of the components of the light emitting element according to one aspect of the present invention will be described below.

≪Light emitting layer≫
In the light emitting layer 130, as the material that can be used for the host material 131, an organic compound having a delayed fluorescence component due to triplet-triplet annihilation (TTA) among the emitted luminescence is preferable. Specifically, a compound having an anthracene skeleton as the first skeleton is preferable, and a compound having a substituent binding to the anthracene skeleton as the second skeleton is preferable. The substituent (second skeleton) that binds to the anthracene skeleton preferably has a carbazole skeleton, and the 9-position of the carbazole skeleton may bind to the anthracene skeleton that is the first skeleton or the aryl group that binds to the anthracene skeleton. , More preferred. Alternatively, the substituent (second skeleton) that binds to the anthracene skeleton has a naphthyl group, and the 2-position of the naphthyl group binds to the aryl group that binds to the first skeleton, the anthracene skeleton or the anthracene skeleton. Is preferable. The aryl group may have another substituent.

Further, in an organic compound having an anthracene skeleton, the triple-term excitation energy level of the substituent bonded to the anthracene skeleton is preferably higher than the triple-term excitation energy level of the anthracene skeleton, and the energy difference from the excitation energy level. Is more preferably 0.5 eV or more.

In the light emitting layer 130, the host material 131 may be composed of one kind of compound or may be composed of a plurality of compounds.

Further, in the light emitting layer 130, the guest material 132 is not particularly limited, but an anthracene derivative, a tetracene derivative, a chrysene derivative, a phenanthrene derivative, a pyrene derivative, a perylene derivative, a stillben derivative, an acridone derivative, a coumarin derivative, a phenoxazine derivative, Phenothiazine derivatives and the like are preferable, and for example, the following materials can be used.

5,6-bis [4- (10-phenyl-9-anthryl) phenyl] -2,2'-bipyridine (abbreviation: PAP2BPy), 5,6-bis [4'-(10-phenyl-9-anthril) Biphenyl-4-yl] -2,2'-bipyridine (abbreviation: PAPP2BPy), N, N'-diphenyl-N, N'-bis [4- (9-phenyl-9H-fluoren-9-yl) phenyl] Pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N, N'-bis (3-methylphenyl) -N, N'-bis [3- (9-phenyl-9H-fluoren-9-yl) Phenyl] pyrene-1,6-diamine (abbreviation: 1,6 mM FLPAPrn), N, N'-bis [4- (9H-carbazole-9-yl) phenyl] -N, N'-diphenylstylben-4,4' -Diamine (abbreviation: YGA2S), 4- (9H-carbazole-9-yl) -4'-(10-phenyl-9-anthril) triphenylamine (abbreviation: YGAPA), 4- (9H-carbazole-9-) Il) -4'-(9,10-diphenyl-2-anthryl) triphenylamine (abbreviation: 2YGAPPA), N, 9-diphenyl-N- [4- (10-phenyl-9-anthryl) phenyl] -9H -Carbazole-3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetra (tert-butyl) perylene (abbreviation: TBP), 4- (10-phenyl-9-anthril) -4'- (9-Phenyl-9H-carbazole-3-yl) triphenylamine (abbreviation: PCBAPA), N, N''-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene) bis [ N, N', N'-triphenyl-1,4-phenylenediamine] (abbreviation: DPABPA), N, 9-diphenyl-N- [4- (9,10-diphenyl-2-anthryl) phenyl] -9H -Carbazole-3-amine (abbreviation: 2PCAPPA), N- [4- (9,10-diphenyl-2-anthryl) phenyl] -N, N', N'-triphenyl-1,4-phenylenediamine (abbreviation) : 2DPAPPA), N, N, N', N', N'', N'', N''', N'''-octaphenyldibenzo [g, p] chrysen-2,7,10,15- Tetraamine (abbreviation: DBC1), coumarin 30, N- (9,10-diphenyl-2-anthril) -N, 9-diphenyl-9H-carbazole-3-3 Amine (abbreviation: 2PCAPA), N- [9,10-bis (1,1'-biphenyl-2-yl) -2-anthril] -N, 9-diphenyl-9H-carbazole-3-amine (abbreviation: 2PCABPhA) ), N- (9,10-diphenyl-2-anthril) -N, N', N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N- [9,10-bis (1,10-bis) 1'-biphenyl-2-yl) -2-anthryl] -N, N', N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPABPhA), 9,10-bis (1,1'-biphenyl) -2-yl) -N- [4- (9H-carbazole-9-yl) phenyl] -N-phenylanthracene-2-amine (abbreviation: 2YGABPhA), N, N, 9-triphenylanthracene-9-amine (Abbreviation: DPhAPhA), Kumarin 6, Kumarin 545T, N, N'-diphenylquinacridone (abbreviation: DPQd), Lubrene, 5,12-bis (1,1'-biphenyl-4-yl) -6,11-diphenyl Tetracene (abbreviation: BPT), 2- (2- {2- [4- (dimethylamino) phenyl] ethenyl} -6-methyl-4H-pyran-4-iriden) propandinitrile (abbreviation: DCM1), 2- {2-Methyl-6- [2- (2,3,6,7-tetrahydro-1H, 5H-benzo [ij] quinolidine-9-yl) ethenyl] -4H-pyran-4-idene} propandinitrile ( Abbreviation: DCM2), N, N, N', N'-tetrakis (4-methylphenyl) tetracene-5,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N, N, N', N'-tetrakis (4-methylphenyl) acenaft [1,2-a] fluoranten-3,10-diamine (abbreviation: p-mPhAFD), 2- {2-isopropyl-6- [2- (1,1,1) 7,7-Tetramethyl-2,3,6,7-Tetrahydro-1H, 5H-benzo [ij] quinolidine-9-yl) ethenyl] -4H-pyran-4-idene} propandinitrile (abbreviation: DCJTI) , 2- {2-term-butyl-6- [2- (1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H, 5H-benzo [ij] quinolidine-9-yl) ) Ethenyl] -4H-pyran-4-idene} propandinitrile (abbreviation: DCJTB), 2- (2,6-bis {2- [4- (dimethylamino) phenyl) ] Ethenyl} -4H-pyran-4-iriden) propandinitrile (abbreviation: BisDCM), 2- {2,6-bis [2- (8-methoxy-1,1,7,7-tetramethyl-2, 3,6,7-Tetrahydro-1H, 5H-benzo [ij] quinolidine-9-yl) ethenyl] -4H-pyran-4-iriden} propandinitrile (abbreviation: BisDCJTM), 5,10,15,20- Tetraphenylbisbenzo [5,6] indeno [1,2,3-cd: 1', 2', 3'-lm] perylene, and the like can be mentioned.

The light emitting layer 130 may have a material other than the host material 131 and the guest material 132.

The material that can be used for the light emitting layer 130 is not particularly limited, but for example, tris (8-quinolinolato) aluminum (III) (abbreviation: Alq), tris (4-methyl-8-quinolinolato) aluminum. (III) (abbreviation: Almq ₃ ), bis (10-hydroxybenzo [h] quinolinato) berylium (II) (abbreviation: BeBq ₂ ), bis (2-methyl-8-quinolinolato) (4-phenylphenolato) aluminum (III) (abbreviation: BAlq), bis (8-quinolinolato) zinc (II) (abbreviation: Znq), bis [2- (2-benzoxazolyl) phenylato] zinc (II) (abbreviation: ZnPBO), bis [2- (2-Benzothiazolyl) phenolato] Metal complexes such as zinc (II) (abbreviation: ZnBTZ), 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxa Diazole (abbreviation: PBD), 1,3-bis [5- (p-tert-butylphenyl) -1,3,4-oxadiazol-2-yl] benzene (abbreviation: OXD-7), 3- (4-Biphenylyl) -4-phenyl-5- (4-tert-butylphenyl) -1,2,4-triazole (abbreviation: TAZ), 2,2', 2''-(1,3,5-) Benzenetriyl) Tris (1-phenyl-1H-benzoimidazole) (abbreviation: TPBI), vasofenantroline (abbreviation: BPhen), vasocuproin (abbreviation: BCP), 9- [4- (5-phenyl-1,3,3) 4-Oxaziazole-2-yl) phenyl] -9H-carbazole (abbreviation: CO11) and other heterocyclic compounds, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (abbreviation) : NPB or α-NPD), N, N'-bis (3-methylphenyl) -N, N'-diphenyl- [1,1'-biphenyl] -4,4'-diamine (abbreviation: TPD), 4 , 4'-Bis [N- (spiro-9,9'-bifluoren-2-yl) -N-phenylamino] Biphenyl (abbreviation: BSD) and other aromatic amine compounds can be mentioned. In addition, condensed polycyclic aromatic compounds such as anthracene derivatives, phenanthrene derivatives, pyrene derivatives, chrysene derivatives, and dibenzo [g, p] chrysene derivatives can be mentioned, and specifically, 9,10-diphenylanthrene (abbreviation: DPAnth). , N, N-diphenyl-9- [4- (10-phenyl-9-anthryl) phenyl] -9H-carbazole-3-amine (abbreviation: CzA1PA), 4- (10-phenyl-9-anthryl) triphenyl Amin (abbreviation: DPhPA), 4- (9H-carbazole-9-yl) -4'-(10-phenyl-9-anthryl) triphenylamine (abbreviation: YGAPA), N, 9-diphenyl-N- [4 -(10-phenyl-9-anthryl) phenyl] -9H-carbazole-3-amine (abbreviation: PCAPA), N, 9-diphenyl-N- {4- [4- (10-phenyl-9-anthryl) phenyl ] Phenanth} -9H-carbazole-3-amine (abbreviation: PCAPBA), N, 9-diphenyl-N- (9,10-diphenyl-2-anthryl) -9H-carbazole-3-amine (abbreviation: 2PCAPA), 6,12-dimethoxy-5,11-diphenylcrisen, N, N, N', N', N'', N'', N''', N'''-octaphenyldibenzo [g, p] chrysen -2,7,10,15-Tetraamine (abbreviation: DBC1), 9- [4- (10-phenyl-9-anthryl) phenyl] -9H-carbazole (abbreviation: CzPA), 3,6-diphenyl-9- [4- (10-phenyl-9-anthryl) phenyl] -9H-carbazole (abbreviation: DPCzPA), 9,10-bis (3,5-diphenylphenyl) anthracene (abbreviation: DPPA), 9,10-di (abbreviation) 2-naphthyl) anthracene (abbreviation: DNA), 2-tert-butyl-9,10-di (2-naphthyl) anthracene (abbreviation: t-BuDNA), 9,9'-biananthrene (abbreviation: Benzene), 9, 9'-(Stilben-3,3'-diyl) diphenanthrene (abbreviation: DPNS), 9,9'-(stilben-4,4'-diyl) diphenanthrene (abbreviation: DPNS2), 3,3', 3 ''-(Benzene-1,3,5-triyl) tripylene (abbreviation: TPB3) and the like can be mentioned. Further, from these and known substances, one or a plurality of substances having an energy gap larger than the energy gap of the guest material 132 may be selected and used.

The light emitting layer 130 may be composed of a plurality of layers of two or more. For example, when the first light emitting layer and the second light emitting layer are laminated in order from the hole transporting layer side to form the light emitting layer 130, a substance having hole transporting property is used as the host material of the first light emitting layer. As the host material of the second light emitting layer, there is a configuration in which a substance having electron transport property is used.

≪Pair of electrodes≫
The electrode 101 and the electrode 102 have a function of injecting holes and electrons into the light emitting layer 130. The electrode 101 and the electrode 102 can be formed by using a metal, an alloy, a conductive compound, a mixture or a laminate thereof, or the like. Aluminum (Al) is a typical example of the metal, and other transition metals such as silver (Ag), tungsten, chromium, molybdenum, copper and titanium, alkali metals such as lithium (Li) and cesium, calcium and magnesium (Mg). ) And other Group 2 metals can be used. A rare earth metal such as ytterbium (Yb) may be used as the transition metal. As the alloy, an alloy containing the above metal can be used, and examples thereof include MgAg and AlLi. Examples of the conductive compound include indium tin oxide (Indium Tin Oxide, hereinafter ITO), indium tin oxide containing silicon or silicon oxide (abbreviation: ITSO), indium tin oxide-zinc oxide (Indium Zinc Oxide), and tungsten oxide. And metal oxides such as indium oxide containing zinc oxide. An inorganic carbon-based material such as graphene may be used as the conductive compound. As described above, one or both of the electrode 101 and the electrode 102 may be formed by laminating a plurality of these materials.

Further, the light emitted from the light emitting layer 130 is taken out through one or both of the electrode 101 and the electrode 102. Therefore, at least one of the electrode 101 and the electrode 102 has a function of transmitting visible light. As a conductive material having a function of transmitting light, the transmittance of visible light is 40% or more and 100% or less, preferably 60% or more and 100% or less, and the resistivity is 1 × 10 ^-2 Ω · cm. The following conductive materials can be mentioned. Further, the electrode that extracts light may be formed of a conductive material having a function of transmitting light and a function of reflecting light. As the conductive material, a conductive material having a visible light reflectance of 20% or more and 80% or less, preferably 40% or more and 70% or less, and a resistivity of 1 × ^10-2 Ω · cm or less is used. Can be mentioned. When a material with low light transmission such as metal or alloy is used for the electrode from which light is taken out, the electrodes 101 and 102 have a thickness sufficient to transmit visible light (for example, a thickness of 1 nm to 10 nm). One or both may be formed.

In the present specification and the like, as the electrode having a function of transmitting light, a material having a function of transmitting visible light and having conductivity may be used, and is represented by, for example, ITO as described above. In addition to the oxide conductor layer, an oxide semiconductor layer or an organic conductor layer containing an organic substance is included. Examples of the organic conductor layer containing an organic substance include a layer containing a composite material obtained by mixing an organic compound and an electron donor (donor), and a composite material obtained by mixing an organic compound and an electron acceptor (acceptor). Examples include layers containing. The resistivity of the transparent conductive layer is preferably 1 × 10 ⁵ Ω · cm or less, and more preferably 1 × 10 ⁴ Ω · cm or less.

Further, as the film forming method of the electrode 101 and the electrode 102, a sputtering method, a vapor deposition method, a printing method, a coating method, an MBE (Molecular Beam Epitaxy) method, a CVD method, a pulse laser deposition method, an ALD (Atomic Layer Deposition) method and the like are used. It can be used as appropriate.

≪Hole injection layer≫
The hole injection layer 111 has a function of promoting hole injection by reducing the hole injection barrier from one of the pair of electrodes (electrode 101 or electrode 102), and has, for example, a transition metal oxide, a phthalocyanine derivative, or an aromatic. It is formed by a group amine or the like. Examples of the transition metal oxide include molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, and manganese oxide. Examples of the phthalocyanine derivative include phthalocyanine and metallic phthalocyanine. Examples of the aromatic amine include a benzidine derivative and a phenylenediamine derivative. High molecular weight compounds such as polythiophene and polyaniline can also be used, and for example, poly (ethylenedioxythiophene) / poly (styrene sulfonic acid), which are self-doped polythiophenes, are typical examples.

As the hole injection layer 111, a layer having a composite material of a hole transporting material and a material exhibiting electron acceptability thereof can also be used. Alternatively, a laminate of a layer containing a material exhibiting electron acceptability and a layer containing a hole transporting material may be used. Charges can be transferred between these materials in a steady state or in the presence of an electric field. Examples of the material exhibiting electron acceptability include organic acceptors such as quinodimethane derivatives, chloranil derivatives, and hexaazatriphenylene derivatives. Specifically, _{7,7,8,8-(abbreviation:} F 4 -TCNQ), chloranil, 2,3,6,7,10,11 -Hexacyano-1,4,5,8,9,12-Hexaazatriphenylene (abbreviation: HAT-CN) or other compound having an electron-withdrawing group (halogen group or cyano group). Further, transition metal oxides, for example, oxides of Group 4 to Group 8 metals can be used. Specifically, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, rhenium oxide and the like. Among them, molybdenum oxide is preferable because it is stable in the atmosphere, has low hygroscopicity, and is easy to handle.

As the hole-transporting material, a material having a higher hole-transporting property than electrons can be used, and a material having a hole mobility of 1 × ^10-6 cm ² / Vs or more is preferable. Specifically, aromatic amines, carbazole derivatives, aromatic hydrocarbons, stilbene derivatives and the like can be used. Moreover, the hole transporting material may be a polymer compound.

As these materials having high hole transport properties, for example, as aromatic amine compounds, N, N'-di (p-tolyl) -N, N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4, 4'-bis [N- (4-diphenylaminophenyl) -N-phenylamino] biphenyl (abbreviation: DPAB), N, N'-bis {4- [bis (3-methylphenyl) amino] phenyl} -N , N'-diphenyl- (1,1'-biphenyl) -4,4'-diamine (abbreviation: DNTPD), 1,3,5-tris [N- (4-diphenylaminophenyl) -N-phenylamino] Examples thereof include benzene (abbreviation: DPA3B).

Specific examples of the carbazole derivative include 3- [N- (4-diphenylaminophenyl) -N-phenylamino] -9-phenylcarbazole (abbreviation: PCzDPA1) and 3,6-bis [N- ( 4-Diphenylaminophenyl) -N-Phenylamino] -9-Phenylcarbazole (abbreviation: PCzDPA2), 3,6-bis [N- (4-diphenylaminophenyl) -N- (1-naphthyl) amino] -9 -Phenylcarbazole (abbreviation: PCzTPN2), 3- [N- (9-phenylcarbazole-3-yl) -N-phenylamino] -9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-bis [N-( 9-Phenylcarbazole-3-yl) -N-Phenylamino] -9-Phenylcarbazole (abbreviation: PCzPCA2), 3- [N- (1-naphthyl) -N- (9-phenylcarbazole-3-yl) amino ] -9-Phenylcarbazole (abbreviation: PCzPCN1) and the like can be mentioned.

Other carbazole derivatives include 4,4'-di (N-carbazolyl) biphenyl (abbreviation: CBP) and 1,3,5-tris [4- (N-carbazolyl) phenyl] benzene (abbreviation: TCPB). ), 9- [4- (10-phenyl-9-anthryl) phenyl] -9H-carbazole (abbreviation: CzPA), 1,4-bis [4- (N-carbazolyl) phenyl] -2,3,5 6-Tetraphenylbenzene or the like can be used.

Examples of aromatic hydrocarbons include 2-tert-butyl-9,10-di (2-naphthyl) anthracene (abbreviation: t-BuDNA) and 2-tert-butyl-9,10-di (1-). Naftyl) anthracene, 9,10-bis (3,5-diphenylphenyl) anthracene (abbreviation: DPPA), 2-tert-butyl-9,10-bis (4-phenylphenyl) anthracene (abbreviation: t-BuDBA), 9,10-di (2-naphthyl) anthracene (abbreviation: DNA), 9,10-diphenylanthracene (abbreviation: DPAnth), 2-tert-butylanthracene (abbreviation: t-BuAnth), 9,10-bis (4) -Methyl-1-naphthyl) anthracene (abbreviation: DMNA), 2-tert-butyl-9,10-bis [2- (1-naphthyl) phenyl] anthracene, 9,10-bis [2- (1-naphthyl) Phenyl] anthracene, 2,3,6,7-tetramethyl-9,10-di (1-naphthyl) anthracene, 2,3,6,7-tetramethyl-9,10-di (2-naphthyl) anthracene, 9,9'-Bianthracene, 10,10'-Diphenyl-9,9'-Bianthracene, 10,10'-Bis (2-phenylphenyl) -9,9'-Bianthracene, 10,10'-Bis [(2) , 3,4,5,6-pentaphenyl) phenyl] -9,9'-bianthracene, anthracene, tetracene, rubrene, perylene, 2,5,8,11-tetra (tert-butyl) perylene and the like. In addition, pentacene, coronene and the like can also be used. As described above, it is more preferable to use an aromatic hydrocarbon having a hole mobility of 1 × 10 ^-6 cm ² / Vs or more and having 14 to 42 carbon atoms.

The aromatic hydrocarbon may have a vinyl skeleton. Examples of aromatic hydrocarbons having a vinyl group include 4,4'-bis (2,2-diphenylvinyl) biphenyl (abbreviation: DPVBi) and 9,10-bis [4- (2,2-)]. Diphenylvinyl) phenyl] anthracene (abbreviation: DPVPA) and the like.

In addition, poly (N-vinylcarbazole) (abbreviation: PVK), poly (4-vinyltriphenylamine) (abbreviation: PVTPA), poly [N- (4- {N'-[4- (4-diphenylamino)) Phenyl] phenyl-N'-phenylamino} phenyl) methacrylamide] (abbreviation: PTPDMA), poly [N, N'-bis (4-butylphenyl) -N, N'-bis (phenyl) benzidine] (abbreviation: A polymer compound such as Poly-TPD) can also be used.

≪Hole transport layer≫
The hole transport layer 112 is a layer containing a hole transport material, and the material exemplified as the material of the hole injection layer 111 can be used. Since the hole transport layer 112 has a function of transporting the holes injected into the hole injection layer 111 to the light emitting layer 130, the hole transport layer 112 may have a HOMO level equal to or close to the HOMO level of the hole injection layer 111. preferable.

As the hole transporting material, in addition to the material exemplified as the material of the hole injection layer 111, as the material having high hole transporting property, for example, 4,4'-bis [N- (1-naphthyl)-. N-phenylamino] biphenyl (abbreviation: NPB or α-NPD) and N, N'-bis (3-methylphenyl) -N, N'-diphenyl- [1,1'-biphenyl] -4,4'- Diamine (abbreviation: TPD), 4,4', 4''-tris (carbazole-9-yl) triphenylamine (abbreviation: TCTA), 4,4', 4''-tris [N- (1-naphthyl) ) -N-phenylamino] triphenylamine (abbreviation: 1'-TNATA), 4,4', 4''-tris (N, N-diphenylamino) triphenylamine (abbreviation: TDATA), 4,4' , 4''-Tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine (abbreviation: MTDATA), 4,4'-bis [N- (spiro-9,9'-bifluorene-2) -Il) -N-phenylamino] biphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl) triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-( 9-Phenylfluoren-9-yl) Triphenylamine (abbreviation: mBPAFLP), N- (9,9-dimethyl-9H-fluoren-2-yl) -N- {9,9-dimethyl-2- [N'-Phenyl-N'-(9,9-dimethyl-9H-fluoren-2-yl) amino] -9H-fluoren-7-yl} phenylamine (abbreviation: DFLADFL), N- (9,9-dimethyl-2) -Diphenylamino-9H-fluoren-7-yl) diphenylamine (abbreviation: DPNF), 2- [N- (4-diphenylaminophenyl) -N-phenylamino] spiro-9,9'-bifluorene (abbreviation: DPASF) , 4-Phenyl-4'-(9-phenyl-9H-carbazole-3-yl) triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazole-) 3-Il) Triphenylamine (abbreviation: PCBBi1BP), 4- (1-naphthyl) -4'-(9-phenyl-9H-carbazole-3-yl) triphenylamine (abbreviation: PCBANB), 4,4' -Di (1-naphthyl) -4 "- (9-phenyl-9H-carbazole-3-yl) triphenylamine (abbreviation: PCBNBB), 4-fe Nildiphenyl- (9-phenyl-9H-carbazole-3-yl) amine (abbreviation: PCA1BP), N, N'-bis (9-phenylcarbazole-3-yl) -N, N'-diphenylbenzene-1, 3-Diamine (abbreviation: PCA2B), N, N', N''-triphenyl-N, N', N''-tris (9-phenylcarbazole-3-yl) benzene-1,3,5-triamine (Abbreviation: PCA3B), N- (4-biphenyl) -N- (9,9-dimethyl-9H-fluoren-2-yl) -9-phenyl-9H-carbazole-3-amine (abbreviation: PCBiF), N -(1,1'-biphenyl-4-yl) -N- [4- (9-phenyl-9H-carbazole-3-yl) phenyl] -9,9-dimethyl-9H-fluoren-2-amine (abbreviation) : PCBbiF), 9,9-dimethyl-N-phenyl-N- [4- (9-phenyl-9H-carbazole-3-yl) phenyl] fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N -[4- (9-phenyl-9H-carbazole-3-yl) phenyl] Spiro-9,9'-bifluoren-2-amine (abbreviation: PCBASF), 2- [N- (9-phenylcarbazole-3-yl) Il) -N-phenylamino] Spiro-9,9'-bifluorene (abbreviation: PCASF), 2,7-bis [N- (4-diphenylaminophenyl) -N-phenylamino] -spiro-9,9' -Bifluorene (abbreviation: DPA2SF), N- [4- (9H-carbazole-9-yl) phenyl] -N- (4-phenyl) phenylaniline (abbreviation: YGA1BP), N, N'-bis [4- ( Carbazole-9-yl) phenyl] -N, N'-diphenyl-9,9-dimethylfluorene-2,7-diamine (abbreviation: YGA2F) and other aromatic amine compounds can be used. In addition, 3- [4- (1-naphthyl) -phenyl] -9-phenyl-9H-carbazole (abbreviation: PCPN), 3- [4- (9-phenanthryl) -phenyl] -9-phenyl-9H-carbazole. (Abbreviation: PCPPn), 3,3'-bis (9-phenyl-9H-carbazole) (abbreviation: PCCP), 1,3-bis (N-carbazolyl) benzene (abbreviation: mCP), 3,6-bis (abbreviation: mCP) 3,5-Diphenylphenyl) -9-phenylcarbazole (abbreviation: CzTP), 4- {3- [3- (9-phenyl-9H-fluorene-9-yl) phenyl] phenyl} dibenzofuran (abbreviation: mmDBFFLBi-II) ), 4,4', 4''- (benzene-1,3,5-triyl) tri (dibenzofuran) (abbreviation: DBF3P-II), 1,3,5-tri (dibenzothiophen-4-yl)- Benzene (abbreviation: DBT3P-II), 2,8-diphenyl-4- [4- (9-phenyl-9H-fluorene-9-yl) phenyl] dibenzothiophene (abbreviation: DBTFLP-III), 4- [4- (9-phenyl-9H-fluorene-9-yl) phenyl] -6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), 4- [3- (triphenylene-2-yl) phenyl] dibenzothiophene (abbreviation: mDBTPTp- Amine compounds such as II), carbazole compounds, thiophene compounds, furan compounds, fluorene compounds, triphenylene compounds, phenanthrene compounds and the like can be used. The substances described here are mainly substances having a hole mobility of 1 × ^10-6 cm ² / Vs or more. However, any substance other than these may be used as long as it is a substance having a higher hole transport property than electrons. The layer containing the substance having a high hole transport property is not limited to a single layer, but may be a layer in which two or more layers made of the above substances are laminated.

The compound that can be used as the hole transport layer 112 may be used for the hole injection layer 111.

≪Electronic transport layer≫
The electron transport layer 118 has a function of transporting electrons injected from the other (electrode 101 or electrode 102) of the pair of electrodes to the light emitting layer 130 via the electron injection layer 119. As the electron transporting material, a material having a higher electron transporting property than holes can be used, and a material having an electron mobility of 1 × 10 ^-6 cm ² / Vs or more is preferable. As a compound that easily receives electrons (a material having an electron transporting property), a π-electron-deficient heteroaromatic compound such as a nitrogen-containing heteroaromatic compound or a metal complex can be used. Specifically, a metal complex having a quinoline ligand, a benzoquinoline ligand, an oxazole ligand, or a thiazole ligand, an oxadiazole derivative, a triazole derivative, a phenanthroline derivative, a pyridine derivative, a bipyridine derivative, and a pyrimidine derivative. And so on.

For example, tris (8-quinolinolato) aluminum (III) (abbreviation: Alq), tris (4-methyl-8-quinolinolato) aluminum (III) (abbreviation: Almq ₃ ), bis (10-hydroxybenzo [h] quinolinato). Berylium (II) (abbreviation: BeBq ₂ ), bis (2-methyl-8-quinolinolato) (4-phenylphenolato) aluminum (III) (abbreviation: BAlq), bis (8-quinolinolato) zinc (II) (abbreviation) : Znq) or the like, which is a layer composed of a metal complex having a quinoline skeleton or a benzoquinoline skeleton. In addition, bis [2- (2-benzoxazolyl) phenolato] zinc (II) (abbreviation: ZnPBO), bis [2- (2-benzothiazolyl) phenolato] zinc (II) (abbreviation: ZnBTZ), etc. A metal complex having an oxazole-based or thiazole-based ligand can also be used. Furthermore, in addition to the metal complex, 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole (abbreviation: PBD) and 1,3-bis [5 -(P-tert-Butylphenyl) -1,3,4-oxadiazol-2-yl] benzene (abbreviation: OXD-7), 9- [4- (5-phenyl-1,3,4-oxa) Diazole-2-yl) phenyl] -9H-carbazole (abbreviation: CO11), 3- (4-biphenylyl) -4-phenyl-5- (4-tert-butylphenyl) -1,2,4-triazole ( Abbreviation: TAZ), 2,2', 2''-(1,3,5-benzenetriyl) Tris (1-phenyl-1H-benzoimidazole) (abbreviation: TPBI), 2- [3- (dibenzothiophene) -4-Il) Phenyl] -1-Phenyl-1H-benzoimidazole (abbreviation: mDBTBIm-II), vasofenantroline (abbreviation: BPhen), vasocuproin (abbreviation: BCP) and other heterocyclic compounds, 2- [3-yl) phenyl] (Dibenzothiophen-4-yl) phenyl] dibenzo [f, h] quinoxaline (abbreviation: 2mDBTPDBq-II), 2- [3'-(dibenzothiophen-4-yl) biphenyl-3-yl] dibenzo [f, h] ] Kinoxalin (abbreviation: 2mDBTBPDBq-II), 2- [3'-(9H-carbazole-9-yl) biphenyl-3-yl] dibenzo [f, h] quinoxalin (abbreviation: 2mCzBPDBq), 2- [4-( 3,6-diphenyl-9H-carbazole-9-yl) phenyl] dibenzo [f, h] quinoxalin (abbreviation: 2CzPDBq-III), 7- [3- (dibenzothiophen-4-yl) phenyl] dibenzo [f, h] Kinoxalin (abbreviation: 7mDBTPDBq-II), 6- [3- (dibenzothiophen-4-yl) phenyl] dibenzo [f, h] quinoxalin (abbreviation: 6mDBTPDBq-II), 4,6-bis [3 -(Phenyl-9-yl) phenyl] pyrimidine (abbreviation: 4,6 mPnP2Pm), 4,6-bis [3- (4-dibenzothienyl) phenyl] pyrimidin (abbreviation: 4,6 mDBTP2Pm-II), 4,6- Bis [3- (9H-carbazole-9-yl) phenyl] pyrimidin (abbreviation: 4,6 mCzP2Pm) and other heterocyclic compounds having a diazine skeleton, 2-{4- [3- (N-phenyl-9H-carbazole) -3-Il) -9H -Carbazole-9-yl] phenyl} -4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzhn) and other heterocyclic compounds having a triazine skeleton and 3,5-bis [3- (9H-) Carbazole-9-yl) phenyl] pyridine (abbreviation: 35DCzPPy), 1,3,5-tri [3- (3-pyridyl) phenyl] benzene (abbreviation: TmPyPB) and other heterocyclic compounds having a pyridine skeleton, 4, Heteroaromatic compounds such as 4'-bis (5-methylbenzoxazole-2-yl) stilben (abbreviation: BzOs) can also be used. In addition, poly (2,5-pyridinediyl) (abbreviation: PPy), poly [(9,9-dihexylfluorene-2,7-diyl) -co- (pyridine-3,5-diyl)] (abbreviation: PF). -Py), poly [(9,9-dioctylfluorene-2,7-diyl) -co- (2,2'-bipyridine-6,6'-diyl)] (abbreviation: PF-BPy) Molecular compounds can also be used. The substances described here are mainly substances having electron mobility of 1 × ^10-6 cm ² / Vs or more. A substance other than the above may be used as the electron transport layer as long as it is a substance having a higher electron transport property than holes. Further, the electron transport layer 118 is not limited to a single layer, but may be a stack of two or more layers made of the above substances.

Further, a layer for controlling the movement of electron carriers may be provided between the electron transport layer 118 and the light emitting layer 130. This is a layer in which a small amount of a substance having a high electron trapping property is added to a material having a high electron transporting property as described above, and the carrier balance can be adjusted by suppressing the movement of electron carriers. Such a configuration is very effective in suppressing problems (for example, reduction in device life) caused by electrons penetrating through the light emitting layer.

≪Electron injection layer≫
The electron injection layer 119 has a function of promoting electron injection by reducing the electron injection barrier from the electrode 102, for example, a group 1 metal, a group 2 metal, or an oxide, a halide, a carbonate, etc. of these. Can be used. Further, a composite material of the above-mentioned electron transporting material and a material exhibiting electron donating property can also be used. Examples of the material exhibiting electron donating property include Group 1 metals, Group 2 metals, and oxides thereof. Specifically, alkali metals such as lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF ₂ ), lithium oxide (LiO _x ), alkaline earth metals, or compounds thereof. Can be used. In addition, rare earth metal compounds such as erbium fluoride (ErF ₃ ) can be used. Further, an electlide may be used for the electron injection layer 119. Examples of the electride include a substance in which a high concentration of electrons is added to a mixed oxide of calcium and aluminum. Further, a substance that can be used in the electron transport layer 118 may be used for the electron injection layer 119.

Further, a composite material formed by mixing an organic compound and an electron donor (donor) may be used for the electron injection layer 119. Such a composite material is excellent in electron injection property and electron transport property because electrons are generated in the organic compound by the electron donor. In this case, the organic compound is preferably a material excellent in transporting generated electrons, and specifically, for example, a substance (metal complex, complex aromatic compound, etc.) constituting the electron transport layer 118 described above. Can be used. The electron donor may be any substance that exhibits electron donating property to the organic compound. Specifically, alkali metals, alkaline earth metals and rare earth metals are preferable, and lithium, cesium, magnesium, calcium, erbium, ytterbium and the like can be mentioned. Further, alkali metal oxides and alkaline earth metal oxides are preferable, and lithium oxides, calcium oxides, barium oxides and the like can be mentioned. A Lewis base such as magnesium oxide can also be used. Further, an organic compound such as tetrathiafulvalene (abbreviation: TTF) can also be used.

The above-mentioned light emitting layer, hole injection layer, hole transport layer, electron transport layer, and electron injection layer are each described by a vapor deposition method (including a vacuum vapor deposition method), an inkjet method, a coating method, gravure printing, or the like. It can be formed by a method. Further, in the above-mentioned light emitting layer, hole injection layer, hole transport layer, electron transport layer, and electron injection layer, in addition to the above-mentioned materials, inorganic compounds such as quantum dots or polymer compounds (oligomers, dendrimers, etc.) Polymers, etc.) may be used.

As the quantum dot material, a colloidal quantum dot material, an alloy type quantum dot material, a core / shell type quantum dot material, a core type quantum dot material, or the like may be used. In addition, materials containing element groups of groups 2 and 16, groups 13 and 15, groups 13 and 17, groups 11 and 17, or groups 14 and 15 may be used. Alternatively, cadmium (Cd), selenium (Se), zinc (Zn), sulfur (S), phosphorus (P), indium (In), tellurium (Te), lead (Pb), gallium (Ga), arsenic (As). ), Aluminum (Al), and other quantum dot materials may be used.

≪Board≫
Further, the light emitting element according to one aspect of the present invention may be manufactured on a substrate made of glass, plastic or the like. The order of production on the substrate may be that the electrodes are laminated in order from the electrode 101 side or in order from the electrode 102 side.

As the substrate on which the light emitting element according to one aspect of the present invention can be formed, for example, glass, quartz, plastic or the like can be used. Further, a flexible substrate may be used. The flexible substrate is a bendable (flexible) substrate, and examples thereof include a plastic substrate made of polycarbonate and polyarylate. Moreover, a film, an inorganic vapor deposition film and the like can also be used. In addition, as long as it functions as a support in the manufacturing process of a light emitting element and an optical element, other than these may be used. Alternatively, it may have a function of protecting the light emitting element and the optical element.

For example, in the present invention and the like, a light emitting element can be formed by using various substrates. The type of substrate is not limited to a specific one. Examples of the substrate include a semiconductor substrate (for example, a single crystal substrate or a silicon substrate), an SOI substrate, a glass substrate, a quartz substrate, a plastic substrate, a metal substrate, a stainless steel substrate, a substrate having a stainless steel still foil, and a tungsten substrate. , Substrates with tungsten foil, flexible substrates, bonded films, papers containing fibrous materials, or substrate films. Examples of glass substrates include barium borosilicate glass, aluminoborosilicate glass, and soda lime glass. Examples of flexible substrates, laminated films, base films, etc. include the following. For example, there are plastics typified by polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyether sulfone (PES), and polytetrafluoroethylene (PTFE). Alternatively, as an example, there is a resin such as acrylic. Alternatively, examples include polypropylene, polyester, polyvinyl fluoride, polyvinyl chloride, and the like. Alternatively, examples include polyamides, polyimides, aramids, epoxies, inorganic vapor-deposited films, and papers.

Further, a flexible substrate may be used as the substrate, and the light emitting element may be formed directly on the flexible substrate. Alternatively, a release layer may be provided between the substrate and the light emitting element. The release layer can be used for separating a part or all of the light emitting element on the substrate, separating it from the substrate, and reprinting it on another substrate. At that time, the light emitting element can be reprinted on a substrate having poor heat resistance or a flexible substrate. For the above-mentioned release layer, for example, a structure in which an inorganic film of a tungsten film and a silicon oxide film is laminated, a structure in which a resin film such as polyimide is formed on a substrate, or the like can be used.

That is, a light emitting element may be formed using a certain substrate, then the light emitting element may be transposed to another substrate, and the light emitting element may be arranged on another substrate. As an example of the substrate on which the light emitting element is transferred, in addition to the above-mentioned substrate, a cellophane substrate, a stone substrate, a wood substrate, a cloth substrate (natural fiber (silk, cotton, linen), synthetic fiber (nylon, polyurethane, polyester) or There are recycled fibers (including acetate, cupra, rayon, recycled polyester), leather substrates, rubber substrates, and the like. By using these substrates, it is possible to obtain a light emitting element that is hard to break, a light emitting element having high heat resistance, a lightweight light emitting element, or a thin light emitting element.

Further, for example, a field effect transistor (FET) may be formed on the above-mentioned substrate, and the light emitting element 120 may be formed on an electrode electrically connected to the FET. This makes it possible to manufacture an active matrix type display device in which the driving of the light emitting element 120 is controlled by the FET.

In the present embodiment, one aspect of the present invention has been described. Alternatively, in another embodiment, one aspect of the present invention will be described. However, one aspect of the present invention is not limited to these. For example, in one aspect of the present invention, an example is shown in which the organic compound contained in the EL layer has an anthracene skeleton, and the emission exhibited by the EL layer has a delayed fluorescence component due to triplet-triplet annihilation. , One aspect of the present invention is not limited to this. In some cases, or depending on the circumstances, in one aspect of the invention, for example, the organic compound contained in the EL layer may not have an anthracene skeleton. Alternatively, the light emission exhibited by the EL layer does not have to have a delayed fluorescence component. Alternatively, for example, in one aspect of the present invention, in the organic compound possessed by the EL layer, the first triplet excited state has a molecular orbital in the anthracene skeleton, and the second triplet excited state is a molecule in the substituent. Although the third triplet excited state having an orbital has an example of having a molecular orbital in the anthracene skeleton, one aspect of the present invention is not limited to this. In some cases, or depending on the circumstances, in one aspect of the invention, for example, in an organic compound having an EL layer, the first triplet excited state may not have a molecular orbital in the anthracene skeleton. Alternatively, the second triplet excited state does not have to have a molecular orbital at the substituent. Alternatively, the third triplet excited state does not have to have a molecular orbital in the anthracene skeleton. Alternatively, for example, in one aspect of the present invention, in the organic compound contained in the EL layer, the energy of the third triplet excited state in the most stable structure of the third triplet excited state is the energy of the third triplet excited state. An example is shown in which the energy is higher than the energy of the first triplet excited state in the most stable structure and lower than the energy of the second triplet excited state in the most stable structure of the third triplet excited state. One aspect of the invention is not limited to this. In some cases, or depending on the circumstances, in one aspect of the invention, for example, in an organic compound having an EL layer, the energy of the third triplet excited state in the most stable structure of the third triplet excited state is , It does not have to be higher than the energy of the first triplet excited state in the most stable structure of the third triplet excited state. Alternatively, the energy of the third triplet excited state in the most stable structure of the third triplet excited state must not be lower than the energy of the second triplet excited state in the most stable structure of the third triplet excited state. May be good. Alternatively, for example, in one aspect of the present invention, in the organic compound of the EL layer, the energy of the singlet excited state is higher than the energy of the second triplet excited state in the most stable structure of the third triplet excited state. Moreover, although the case where the energy is equal to or less than the energy of the third triplet excited state in the most stable structure of the third triplet excited state is shown, one aspect of the present invention is not limited to this. In some cases, or depending on the circumstances, in one aspect of the invention, for example, in an organic compound having an EL layer, the energy of the singlet excited state is the second in the most stable structure of the third triplet excited state. It does not have to be higher than the energy of the triplet excited state of. Alternatively, the energy of the singlet excited state does not have to be less than or equal to the energy of the third triplet excited state in the most stable structure of the third triplet excited state.

As described above, the configuration shown in this embodiment can be used in combination with other embodiments as appropriate.

(Embodiment 2)
In the present embodiment, a light emitting element having a configuration different from that shown in the first embodiment and a light emitting mechanism of the light emitting element will be described below with reference to FIGS. 9 and 10. In addition, in FIGS. 9 and 10, the same hatch pattern may be used in places having the same function as the reference numerals shown in FIG. 1A, and the reference numerals may be omitted. In addition, parts having the same function may be designated by the same reference numerals, and detailed description thereof may be omitted.

<Structure example 1 of light emitting element>
FIG. 9A is a schematic cross-sectional view of the light emitting element 450.

The light emitting element 450 shown in FIG. 9A has a plurality of light emitting units (in FIG. 9A, a light emitting unit 441 and a light emitting unit 442) between a pair of electrodes (electrode 401 and electrode 402). One light emitting unit has the same configuration as the EL layer 100 shown in FIG. That is, the light emitting element 120 shown in FIG. 1 has one light emitting unit, and the light emitting element 450 has a plurality of light emitting units. In the light emitting element 450, the electrode 401 functions as an anode and the electrode 402 functions as a cathode, which will be described below. However, the configuration of the light emitting element 450 may be reversed.

Further, in the light emitting element 450 shown in FIG. 9A, the light emitting unit 441 and the light emitting unit 442 are laminated, and a charge generation layer 445 is provided between the light emitting unit 441 and the light emitting unit 442. The light emitting unit 441 and the light emitting unit 442 may have the same configuration or different configurations. For example, it is preferable to use the EL layer 100 shown in FIG. 1 for the light emitting unit 441 and to use a light emitting layer having a phosphorescent material as the light emitting material for the light emitting unit 442.

That is, the light emitting element 450 has a light emitting layer 420 and a light emitting layer 430. Further, the light emitting unit 441 has a hole injection layer 411, a hole transport layer 412, an electron transport layer 413, and an electron injection layer 414 in addition to the light emitting layer 420. Further, the light emitting unit 442 has a hole injection layer 416, a hole transport layer 417, an electron transport layer 418, and an electron injection layer 419 in addition to the light emitting layer 430.

The charge generation layer 445 has a structure in which an acceptor substance which is an electron acceptor is added to a hole transporting material, but a donor substance which is an electron donor is added to the electron transporting material. May be. Moreover, both of these configurations may be laminated.

When the charge generation layer 445 contains a composite material of an organic compound and an acceptor substance, the composite material may be a composite material that can be used for the hole injection layer 111 shown in the first embodiment. As the organic compound, various compounds such as an aromatic amine compound, a carbazole compound, an aromatic hydrocarbon, and a polymer compound (oligomer, dendrimer, polymer, etc.) can be used. As the organic compound, it is preferable to apply a compound having a hole mobility of 1 × ^10-6 cm ² / Vs or more. However, any substance other than these may be used as long as it is a substance having a higher hole transport property than electrons. Since the composite material of the organic compound and the acceptor substance is excellent in carrier injection property and carrier transport property, low voltage drive and low current drive can be realized. When the surface of the light emitting unit on the anode side is in contact with the charge generating layer 445 as in the light emitting unit 442, the charge generating layer 445 also serves as a hole injection layer or a hole transport layer of the light emitting unit. Therefore, it is not necessary to provide the hole injection layer or the hole transport layer in the light emitting unit.

The charge generation layer 445 may be formed as a laminated structure in which a layer containing a composite material of an organic compound and an acceptor substance and a layer composed of another material are combined. For example, a layer containing a composite material of an organic compound and an acceptor substance and a layer containing a compound selected from electron-donating substances and a compound having high electron transportability may be formed in combination. Further, a layer containing a composite material of an organic compound and an acceptor substance and a layer containing a transparent conductive film may be formed in combination.

The charge generation layer 445 sandwiched between the light emitting unit 441 and the light emitting unit 442 injects electrons into one light emitting unit and holes in the other light emitting unit when a voltage is applied to the electrode 401 and the electrode 402. Anything that injects. For example, in FIG. 9A, when a voltage is applied so that the potential of the electrode 401 is higher than the potential of the electrode 402, the charge generation layer 445 injects electrons into the light emitting unit 441 and emits light unit 442. Inject holes into the.

From the viewpoint of light extraction efficiency, the charge generation layer 445 preferably has light transmittance with respect to visible light (specifically, the transmittance of visible light with respect to the charge generation layer 445 is 40% or more). Further, the charge generation layer 445 functions even if the conductivity is lower than that of the pair of electrodes (electrode 401 and electrode 402).

By forming the charge generation layer 445 using the above-mentioned material, it is possible to suppress an increase in the drive voltage when the light emitting layers are laminated.

Further, in FIG. 9A, a light emitting element having two light emitting units has been described, but the same can be applied to a light emitting element in which three or more light emitting units are laminated. As shown in the light emitting element 450, by arranging a plurality of light emitting units separated by a charge generation layer between a pair of electrodes, high brightness light emission is possible while keeping the current density low, and a light emitting element having a longer life. Can be realized. Further, it is possible to realize a light emitting element having low power consumption.

By applying the configuration of the EL layer 100 shown in FIG. 1 to at least one of the plurality of units, it is possible to provide a light emitting element having high luminous efficiency.

Further, the light emitting layer 420 has a host material 421 and a guest material 422. Further, the light emitting layer 430 has a host material 431 and a guest material 432. Further, the host material 431 has an organic compound 431_1 and an organic compound 431_2.

Further, in the present embodiment, the light emitting layer 420 has the same configuration as the light emitting layer 130 shown in FIG. That is, the host material 421 and the guest material 422 of the light emitting layer 420 correspond to the host material 131 and the guest material 132 of the light emitting layer 130, respectively. Further, the guest material 432 of the light emitting layer 430 will be described below as a phosphorescent material. The electrodes 401, electrodes 402, hole injection layers 411 and 416, hole transport layers 412 and 417, electron transport layers 413 and 418, and electron injection layers 414 and 419 are the electrodes 101 and electrodes shown in the first embodiment. It corresponds to 102, the hole injection layer 111, the hole transport layer 112, the electron transport layer 118, and the electron injection layer 119, respectively. Therefore, in the present embodiment, the detailed description thereof will be omitted.

<< Light emitting mechanism of light emitting layer 420 >>
The light emitting mechanism of the light emitting layer 420 is the same as that of the light emitting layer 130 shown in FIG.

<< Light emitting mechanism of light emitting layer 430 >>
Next, the light emitting mechanism of the light emitting layer 430 will be described below.

The organic compound 431_1 contained in the light emitting layer 430 and the organic compound 431_2 form an excited complex.

The combination of the organic compound 431_1 and the organic compound 431_2 forming the excitation complex in the light emitting layer 430 may be any combination capable of forming the excitation complex, but one is a compound having hole transporting property and the other. Is more preferably a compound having electron transportability.

FIG. 9B shows the correlation of the energy levels of the organic compound 431_1, the organic compound 431_2, and the guest material 432 in the light emitting layer 430. The notation and reference numerals in FIG. 9B are as follows.
Host (431_1): Host material (organic compound 431_1)
Host (431_2): Host material (organic compound 431_2)
-Guest (432): Guest material 432 (phosphorescent material)
・ S _PH : The lowest level of the single-term excited state of the host material (organic compound 431_1) ・ T _PH : The lowest level of the triple-term excited state of the host material (organic compound 431_1) ・ T _PG : Guest material 432 ( The lowest level of the triple-term excited state of the phosphorescent material) ・ S _PE : The lowest level of the single-term excited state of the excited complex ・ T _PE : The lowest level of the triple-term excited state of the excited complex

An excited complex is formed by the organic compound 431_1 and the organic compound 431_2.該励will be adjacent to each other and the lowest level of the singlet excited state of the electromotive complex (S _PE) and the lowest level of the triplet excited state of the exciplex (T _PE) (Fig. 9 (B) Route C reference).

Then, the energies of both the _SP and T _PE of the excited complex are transferred to the lowest level (T _PG ) of the triplet excited state of the guest material 432 (phosphorescent material) to obtain light emission (FIG. 9 (B)). ) See Route D).

In addition, the process of Route C and Route D shown above may be referred to as ExTET (Exciplex-Triplet Energy Transfer) in the present specification and the like.

Further, the organic compound 431_1 and the organic compound 431_2 form an excited complex by receiving holes on one side and electrons on the other side. Alternatively, when one is in an excited state, it interacts with the other to form an excited complex. Therefore, most of the excitons in the light emitting layer 430 exist as an excited complex. Since the excited complex has a smaller band gap than both the organic compound 431_1 and the organic compound 431_2, the driving voltage can be lowered by forming the excited complex from the recombination of one hole and the other electron.

By configuring the light emitting layer 430 as described above, it is possible to efficiently obtain light emission from the guest material 432 (phosphorescent material) of the light emitting layer 430.

It is preferable that the light emitted from the light emitting layer 420 has a peak of light emission on the shorter wavelength side than the light emitted from the light emitting layer 430. A light emitting element using a phosphorescent material that emits light having a short wavelength tends to deteriorate in brightness quickly. Therefore, it is possible to provide a light emitting element having a small luminance deterioration by using fluorescent light emission for short wavelength light emission.

Further, by obtaining light having different emission wavelengths in the light emitting layer 420 and the light emitting layer 430, it is possible to obtain a multicolor light emitting element. In this case, since the emission spectrum is the combined light of emission having different emission peaks, the emission spectrum has at least two maximum values.

The above configuration is also suitable for obtaining white light emission. White light emission can be obtained by making the light of the light emitting layer 420 and the light emitting layer 430 have a complementary color relationship with each other.

Further, by using a plurality of light emitting substances having different light emitting wavelengths for either or both of the light emitting layer 420 and the light emitting layer 430, it is possible to obtain highly color rendering white light emission composed of three primary colors or four or more light emitting colors. it can. In this case, one or both of the light emitting layer 420 and the light emitting layer 430 may be further divided into layers, and different light emitting materials may be contained in each of the divided layers.

<Structure example 2 of light emitting element>
Next, a configuration example different from the light emitting element shown in FIG. 9 will be described below with reference to FIGS. 10A and 10B.

FIG. 10A is a schematic cross-sectional view of the light emitting element 452.

The light emitting element 452 shown in FIG. 10A has a structure in which the EL layer 400 is sandwiched between a pair of electrodes (electrode 401 and electrode 402). In the light emitting element 452, the electrode 401 functions as an anode and the electrode 402 functions as a cathode.

Further, the EL layer 400 has a light emitting layer 420 and a light emitting layer 430. Further, in the light emitting element 452, as the EL layer 400, in addition to the light emitting layer 420 and the light emitting layer 430, the hole injection layer 411, the hole transport layer 412, the electron transport layer 418, and the electron injection layer 419 are shown. However, these laminated structures are examples, and the configuration of the EL layer 400 in the light emitting element 452 is not limited to these. For example, in the EL layer 400, the stacking order of each of the above layers may be changed. Alternatively, the EL layer 400 may be provided with a functional layer other than the above-mentioned layers. The functional layer may be configured to have, for example, a function of injecting carriers (electrons or holes), a function of transporting carriers, a function of suppressing carriers, and a function of generating carriers.

Further, the light emitting layer 420 has a host material 421 and a guest material 422. Further, the light emitting layer 430 has a host material 431 and a guest material 432. The host material 431 has an organic compound 431_1 and an organic compound 431_2. The guest material 422 is a fluorescent material and the guest material 432 is a phosphorescent material, which will be described below.

<< Light emitting mechanism of light emitting layer 420 and light emitting layer 430 >>
The light emitting mechanism of the light emitting layer 420 is the same as that of the light emitting layer 130 shown in FIG. 1 (C). The light emitting mechanism of the light emitting layer 430 is the same as that of the light emitting layer 430 shown in FIG. 9B.

As shown in the light emitting element 452, when the light emitting layer 420 and the light emitting layer 430 are in contact with each other, energy transfer from the excited complex to the host material 421 of the light emitting layer 420 at the interface between the light emitting layer 420 and the light emitting layer 430. Even if (especially energy transfer of the triplet excitation level) occurs, the triplet excitation energy can be converted into light emission in the light emitting layer 420.

It is preferable that the T1 level of the host material 421 of the light emitting layer 420 is lower than the T1 level of the organic compound 431_1 and the organic compound 431_2 possessed by the light emitting layer 430. Further, in the light emitting layer 420, the S1 level of the host material 421 is higher than the S1 level of the guest material 422 (fluorescent material), and the T1 level of the host material 421 is the T1 level of the guest material 422 (fluorescent material). It is preferable that it is lower than the rank.

Specifically, FIG. 10B shows the correlation of energy levels when TTA is used for the light emitting layer 420 and ExTET is used for the light emitting layer 430. The notation and reference numerals in FIG. 10B are as follows.
-Fluorescence EML (420): Fluorescent light emitting layer (light emitting layer 420)
Phosphorescence EML (430): Phosphorescent light emitting layer (light emitting layer 430)
_-SFH : The lowest level of the single-term excited state of the host material 421- _TFH : The lowest level of the triple-term excited state of the host material 421-S _FG : The single-term excited state of the guest material 422 (fluorescent material) The lowest level of T _FG : The lowest level of the triplet excited state of the guest material 422 (fluorescent material) ・ S _PH : The lowest level of the single-term excited state of the host material (organic compound 431_1) ・ T _PH : the lowest level · T _PG triplet excited state of the host material (organic compound _{431_1):} guest material 432 lowest level · S _E triplet excited state of (phosphorescent _material): singlet excited state of the exciplex The lowest level of _TE : The lowest level of the triplet excited state of the excited complex

As shown in FIG. 10B, since the excited complex exists only in the excited state, exciton diffusion between the excited complex and the excited complex is unlikely to occur. The excitation of the exciplex level _(S E, _{T E)} is an organic compound having a light-emitting layer 430 431_1 (i.e., host material for a phosphorescent material) excitation level _{(S PH, T PH)} of is lower than the excitation No energy diffusion from the complex to the organic compound 431_1 also occurs. That is, since the exciton diffusion distance of the excitation complex is short in the phosphorescent light emitting layer (light emitting layer 430), the efficiency of the phosphorescent light emitting layer (light emitting layer 430) can be maintained. Further, at the interface between the fluorescent light emitting layer (light emitting layer 420) and the phosphorescent light emitting layer (light emitting layer 430), a part of the triplet excitation energy of the excitation complex of the phosphorescent light emitting layer (light emitting layer 430) is a fluorescent light emitting layer (light emitting layer). Even if it diffuses to 420), the triplet excitation energy of the fluorescent light emitting layer (light emitting layer 420) generated by the diffusion is emitted through TTA, so that the energy loss can be reduced.

As described above, the light emitting element 452 can be a light emitting element having high luminous efficiency because energy loss is reduced by using ExTET for the light emitting layer 430 and TTA for the light emitting layer 420. .. Further, as shown in the light emitting element 452, when the light emitting layer 420 and the light emitting layer 430 are in contact with each other, the energy loss can be reduced and the number of layers of the EL layer 400 can be reduced. Therefore, it is possible to obtain a light emitting element having a low manufacturing cost.

The light emitting layer 420 and the light emitting layer 430 may not be in contact with each other. In this case, the excited state of the organic compound 431_1, the organic compound 431_2, or the guest material 432 (phosphorescent material) generated in the light emitting layer 430 is transferred to the host material 421 or the guest material 422 (fluorescent material) in the light emitting layer 420. Energy transfer by the Dexter mechanism (particularly triplet energy transfer) can be prevented. Therefore, the layer provided between the light emitting layer 420 and the light emitting layer 430 may have a thickness of about several nm.

The layer provided between the light emitting layer 420 and the light emitting layer 430 may be made of a single material, but may contain both a hole transporting material and an electron transporting material. When composed of a single material, a bipolar material may be used. Here, the bipolar material refers to a material having an electron-hole mobility ratio of 100 or less. Further, a hole transporting material, an electron transporting material, or the like may be used. Alternatively, at least one of them may be formed of the same material as the host material (organic compound 431_1 or organic compound 431_2) of the light emitting layer 430. This facilitates the fabrication of the light emitting element and reduces the drive voltage. Further, the hole transporting material and the electron transporting material may form an excited complex, which can effectively prevent the diffusion of excitons. Specifically, it prevents energy transfer from the excited state of the host material (organic compound 431_1) or guest material 432 (phosphorescent material) of the light emitting layer 430 to the host material 421 or guest material 422 (fluorescent material) of the light emitting layer 420. be able to.

In the light emitting device 452, the carrier recombination region is preferably formed with a certain distribution. Therefore, the light emitting layer 420 or the light emitting layer 430 preferably has an appropriate carrier trapping property, and in particular, the guest material 432 (phosphorescent material) contained in the light emitting layer 430 preferably has an electron trapping property.

It is preferable that the light emitted from the light emitting layer 420 has a peak of light emission on the shorter wavelength side than the light emitted from the light emitting layer 430. A light emitting element using a phosphorescent material that emits light having a short wavelength tends to deteriorate in brightness quickly. Therefore, it is possible to provide a light emitting element having a small luminance deterioration by using fluorescent light emission for short wavelength light emission.

Further, by obtaining light having different emission wavelengths in the light emitting layer 420 and the light emitting layer 430, it is possible to obtain a multicolor light emitting element. In this case, since the emission spectrum is the combined light of emission having different emission peaks, the emission spectrum has at least two maximum values.

The above configuration is also suitable for obtaining white light emission. White light emission can be obtained by making the light of the light emitting layer 420 and the light emitting layer 430 have a complementary color relationship with each other.

Further, by using a plurality of light emitting substances having different light emitting wavelengths in the light emitting layer 420, it is possible to obtain white light emission having high color rendering properties, which is composed of three primary colors or four or more light emitting colors. In this case, the light emitting layer 420 may be further divided into layers, and different light emitting materials may be contained in each of the divided layers.

<Examples of materials that can be used for the light emitting layer>
Next, the materials that can be used for the light emitting layer 420 and the light emitting layer 430 will be described below.

<< Materials that can be used for the light emitting layer 420 >>
In the light emitting layer 420, the host material 421 is present in the largest weight ratio, and the guest material 422 (fluorescent material) is dispersed in the host material 421. It is preferred that the S1 level of the host material 421 is higher than the S1 level of the guest material 422 (fluorescent material) and the T1 level of the host material 421 is lower than the T1 level of the guest material 422 (fluorescent material). ..

As the material that can be used for the light emitting layer 420, the material that can be used for the light emitting layer 130 shown in the first embodiment may be used. By doing so, it is possible to manufacture a light emitting device having a high ratio of delayed fluorescence of light emission and high light emission efficiency.

<< Materials that can be used for the light emitting layer 430 >>
In the light emitting layer 430, the host material 431 is present in the largest weight ratio, and the guest material 432 (phosphorescent material) is dispersed in the host material 431. The T1 level of the host material 431 (organic compound 431_1 and organic compound 431_2) of the light emitting layer 430 is preferably higher than the T1 level of the guest material 422 (fluorescent material) of the light emitting layer 420.

Examples of the organic compound 431_1 include zinc and aluminum-based metal complexes, oxadiazole derivatives, triazole derivatives, benzoimidazole derivatives, quinoxalin derivatives, dibenzoquinoxaline derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, pyrimidine derivatives, triazine derivatives, and pyridine derivatives. Examples thereof include bipyridine derivatives and phenanthroline derivatives. Other examples include aromatic amines and carbazole derivatives. Specifically, the electron-transporting material and the hole-transporting material shown in the first embodiment can be used.

The organic compound 431_2 is a combination capable of forming an excited complex with the organic compound 431_1. Specifically, the electron-transporting material and the hole-transporting material shown in the first embodiment can be used. In this case, the emission peak of the excitation complex formed by the organic compound 431_1 and the organic compound 431_2 is the absorption band of the triple term MLCT (Metal to Dragon Charge Transfer) transition of the guest material 432 (phosphorescent material), more specifically. It is preferable to select the organic compound 431_1, the organic compound 431_2, and the guest material 432 (phosphorescent material) so as to overlap the absorption band on the longest wavelength side. As a result, a light emitting element having dramatically improved luminous efficiency can be obtained. However, when a thermally activated delayed fluorescent material is used instead of the phosphorescent material, the absorption band on the longest wavelength side is preferably a singlet absorption band.

Examples of the guest material 432 (phosphorescent material) include iridium, rhodium, or platinum-based organometallic complexes, or metal complexes, and among them, organic iridium complexes, for example, iridium-based orthometal complexes are preferable. Examples of the ligand for orthometallation include 4H-triazole ligand, 1H-triazole ligand, imidazole ligand, pyridine ligand, pyrimidine ligand, pyrazine ligand, and isoquinolin ligand. Can be mentioned. Examples of the metal complex include a platinum complex having a porphyrin ligand.

Examples of substances having a blue or green emission peak include tris {2- [5- (2-methylphenyl) -4- (2,6-dimethylphenyl) -4H-1,2,4-triazole-3. -Il-κN2] Phenyl-κC} iridium (III) (abbreviation: Ir (mpptz-dmp) ₃ ), tris (5-methyl-3,4-diphenyl-4H-1,2,4-triazolat) iridium (III) ) (Abbreviation: Ir (Mptz) ₃ ), Tris [4- (3-biphenyl) -5-isopropyl-3-phenyl-4H-1,2,4-triazolat] Iridium (III) (abbreviation: Ir (iPrptz-) 3b) ₃ ), 4H such as Tris [3- (5-biphenyl) -5-isopropyl-4-phenyl-4H-1,2,4-triazolate] iridium (III) (abbreviation: Ir (iPr5btz) ₃ ) -Organic metal iridium complex having a triazole skeleton and tris [3-methyl-1- (2-methylphenyl) -5-phenyl-1H-1,2,4-triazolate] iridium (III) (abbreviation: Ir (Mptz1) _-mp) 3), tris (1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato) iridium (III) (abbreviation: such as _{Ir (Prptz1-Me) 3)} 1H- Organic metal iridium complex having a triazole skeleton, fac-tris [1- (2,6-diisopropylphenyl) -2-phenyl-1H-imidazole] iridium (III) (abbreviation: Ir (iPrpmi) ₃ ), tris [3 -(2,6-Dimethylphenyl) -7-Methylimidazole [1,2-f] phenanthridinato] Iridium (III) (abbreviation: Ir (dmimpt-Me) ₃ ) -like organic metal having an imidazole skeleton Iridium complex, bis [2- (4', 6'-difluorophenyl) pyridinato-N, C ^2' ] iridium (III) tetrakis (1-pyrazolyl) borate (abbreviation: FIR6), bis [2- (4') , 6'-difluorophenyl) pyridinato-N, C ^2' ] iridium (III) picolinate (abbreviation: Firpic), bis {2- [3', 5'-bis (trifluoromethyl) phenyl] pyridinato-N, C ^2' } Iridium (III) picolinate (abbreviation: Ir (CF ₃ ppy) ₂ (pic)), bis [2- (4', 6'-difluorophenyl) pyridinato-N, C ^2' ] An organometallic iridium complex having a phenylpyridine derivative having an electron-withdrawing group such as iridium (III) acetylacetonate (abbreviation: FIR (acac)) as a ligand can be mentioned. Among the above, the organometallic iridium complex having a 4H-triazole skeleton is particularly preferable because it is excellent in reliability and luminous efficiency.

Examples of substances having a green or yellow emission peak include tris (4-methyl-6-phenylpyrimidinato) iridium (III) (abbreviation: Ir (mppm) ₃ ) and tris (4-t-butyl). -6-Phenylpyrimidinato) Iridium (III) (abbreviation: Ir (tBuppm) ₃ ), (Acetylacetone) bis (6-methyl-4-phenylpyrimidinato) Iridium (III) (abbreviation: Ir (mppm) ₃ ) ) ₂ (acac)), (acetylacetonato) bis (6-tert-butyl-4-phenylpyrimidinato) iridium (III) (abbreviation: Ir (tBuppm) ₂ (acac)), (acetylacetonato) bis [6- (2-norbornyl) -4-phenylpyrimidinato] iridium (III) (abbreviation: Ir (nbppm) ₂ (acac)), (acetylacetonato) bis [5-methyl-6- (2-methyl) Phenyl) -4-phenylpyrimidinato] iridium (III) (abbreviation: Ir (mpmppm) ₂ (acac)), (acetylacetonato) bis {4,6-dimethyl-2- [6- (2,6--) Dimethylphenyl) -4-pyrimidinyl-κN3] phenyl-κC} iridium (III) (abbreviation: Ir (dmppm-dmp) ₂ (acac)), (acetylacetonato) bis (4,6-diphenylpyrimidinato) iridium Organic metal iridium complexes having a pyrimidine skeleton such as (III) (abbreviation: Ir (dppm) ₂ (acac)) and (acetylacetonato) bis (3,5-dimethyl-2-phenylpyrazinato) iridium ( III) (abbreviation: Ir (mppr-Me) ₂ (acac)), (acetylacetonato) bis (5-isopropyl-3-methyl-2-phenylpyrazinato) iridium (III) (abbreviation: Ir (mppr-) Organic metal iridium complex having a pyrazine skeleton such as iPr) ₂ (acac)), tris (2-phenylpyridinato-N, C ^2' ) iridium (III) (abbreviation: Ir (ppy) ₃ ), bis (2-Phenylpyridinato-N, C ^2' ) Iridium (III) Acetylacetoneate (abbreviation: Ir (ppy) ₂ (acac)), Bis (benzo [h] quinolinato) Iridium (III) Acetylacetoneate ( Abbreviation: Ir (bzq) ₂ (acac)), Tris (benzo [h] quinolinato) iridium (III) (abbreviation: I r (bzq) ₃ ), Tris (2-phenylquinolinato-N, C ^2' ) Iridium (III) (abbreviation: Ir (pq) ₃ ), Bis (2-phenylquinolinato-N, C ^2' ) iridium (III) Organic metal iridium complex having a pyridine skeleton such as acetylacetonate (abbreviation: Ir (pq) ₂ (acac)) and bis (2,4-diphenyl-1,3-oxazolato-N, C ^2'). ) Iridium (III) Acetylacetone (abbreviation: Ir (dpo) ₂ (acac)), Bis {2- [4'-(perfluorophenyl) phenyl] pyridinato-N, C ^2' } Iridium (III) Acetylacetone Nate (abbreviation: Ir (p-PF-ph) ₂ (acac)), bis (2-phenylbenzothiazolato-N, C ^2' ) iridium (III) acetylacetoneate (abbreviation: Ir (bt) ₂ (abbreviation: Ir (bt) ₂ ) In addition to organic metal iridium complexes such as acac)), rare earth metal complexes such as tris (acetylacetonato) (monophenanthrolin) terbium (III) (abbreviation: Tb (acac) ₃ (Phen)) can be mentioned. Among the above, the organometallic iridium complex having a pyrimidine skeleton is particularly preferable because it is remarkably excellent in reliability and luminous efficiency.

Examples of substances having a yellow or red emission peak include (diisobutyrylmethanato) bis [4,6-bis (3-methylphenyl) pyrimidinato] iridium (III) (abbreviation: Ir (5 mdppm) ₂ (abbreviation: Ir (5 mdppm)) ₂ ( dibm)), bis [4,6-bis (3-methylphenyl) pyrimidinato] (dipivaloylmethanato) iridium (III) (abbreviation: Ir (5mdppm) ₂ (dpm)), bis [4,6-di (Naphthalen-1-yl) pyrimidinato] (dipivaloylmethanato) Iridium (III) (abbreviation: Ir (d1npm) ₂ (dpm)) and other organic metal iridium complexes with a pyrimidine skeleton, and (acetylacetonato) Bis (2,3,5-triphenylpyrazinato) Iridium (III) (abbreviation: Ir (tppr) ₂ (acac)), bis (2,3,5-triphenylpyrazinato) (zipivaloylme) Tanato) Iridium (III) (abbreviation: Ir (tppr) ₂ (dpm)), (acetylacetonato) bis [2,3-bis (4-fluorophenyl) quinoxalinato] iridium (III) (abbreviation: [Ir (Fdpq) ) ₂ (acac)]) organic metal iridium complex having a pyrazine skeleton, tris (1-phenylisoquinolinato-N, C ^2' ) iridium (III) (abbreviation: Ir (piq) ₃ ), bis In addition to organic metal iridium complexes with a pyridine skeleton such as (1-phenylisoquinolinato-N, C ^2' ) iridium (III) acetylacetonate (abbreviation: Ir (piq) ₂ (acac)), a few , 7,8,12,13,17,18-octaethyl-21H, 23H-porphyrin platinum (II) (abbreviation: PtOEP) and platinum complexes, tris (1,3-diphenyl-1,3-propanedio) Nato) (monophenanthroline) Europium (III) (abbreviation: Eu (DBM) ₃ (Phen)), Tris [1- (2-tenoyl) -3,3,3-trifluoroacetonato] (monophenanthroline) Europium ( Examples thereof include rare earth metal complexes such as III) (abbreviation: Eu (TTA) ₃ (Phen)). Among the above, the organometallic iridium complex having a pyrimidine skeleton is particularly preferable because it is remarkably excellent in reliability and luminous efficiency. Further, the organometallic iridium complex having a pyrazine skeleton can obtain red light emission with good chromaticity.

The light emitting material contained in the light emitting layer 430 may be any material that can convert triplet excitation energy into light emission. Examples of the material capable of converting the triplet excitation energy into light emission include a thermally activated delayed fluorescent (TADF) material in addition to the phosphorescent material. Therefore, the portion described as phosphorescent material may be read as thermal activated delayed fluorescent material. The heat-activated delayed fluorescent material has a small difference between the triplet excited energy level and the singlet excited energy level, and has a function of converting energy from the triplet excited state to the singlet excited state by crossing the inverse terms. It is a material having. Therefore, the triplet excited state can be up-converted to the singlet excited state (intersystem crossing) with a small amount of thermal energy, and light emission (fluorescence) from the singlet excited state can be efficiently exhibited. Further, as a condition for efficiently obtaining thermally activated delayed fluorescence, the energy difference between the triplet excitation energy level and the singlet excitation energy level is preferably greater than 0 eV and 0.2 eV or less, and more preferably greater than 0 eV and 0. It can be mentioned that it is 1 eV or less.

Further, the material exhibiting thermal activated delayed fluorescence may be a material capable of generating a singlet excited state from a triplet excited state by an intersystem crossing alone, or an excited complex (also referred to as excimer or Exciplex). It may be composed of a plurality of materials forming the above.

When the Thermally Activated Delayed Fluorescent Material is composed of one kind of material, for example, the following materials can be used.

First, fullerenes and derivatives thereof, acridine derivatives such as proflavine, eosin and the like can be mentioned. Examples thereof include metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), palladium (Pd) and the like. Examples of the metal-containing porphyrin include a protoporphyrin-tin fluoride complex (SnF ₂ (Proto IX)), a mesoporphyrin-tin fluoride complex (SnF ₂ (Meso IX)), and a hematoporphyrin-tin fluoride complex (SnF). ₂ (Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF ₂ (Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF ₂ (OEP)), etioporphyrin-tin fluoride Examples thereof include a complex (SnF ₂ (Etio I)), an octaethylporphyrin-platinum chloride complex (PtCl ₂ OEP), and the like.

Further, as the thermally activated delayed fluorescent material composed of one kind of material, a heterocyclic compound having a π-electron excess type heteroaromatic ring and a π-electron deficiency type heteroaromatic ring can also be used. Specifically, 2- (biphenyl-4-yl) -4,6-bis (12-phenylindro [2,3-a] carbazole-11-yl) -1,3,5-triazine (abbreviation:: PIC-TRZ), 2- {4- [3- (N-phenyl-9H-carbazole-3-yl) -9H-carbazole-9-yl] phenyl} -4,6-diphenyl-1,3,5- Triazine (abbreviation: PCCzPTzn), 2- [4- (10H-phenoxazine-10-yl) phenyl] -4,6-diphenyl-1,3,5-triazine (abbreviation: PXZ-TRZ), 3- [4 -(5-Phenyl-5,10-dihydrophenazine-10-yl) phenyl] -4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3- (9,9-dimethyl- 9H-acridine-10-yl) -9H-xanthene-9-one (abbreviation: ACRXTN), bis [4- (9,9-dimethyl-9,10-dihydroacridine) phenyl] sulfone (abbreviation: DMAC-DPS) Examples thereof include 10-phenyl-10H, 10'H-spiro [acridine-9,9'-anthracene] -10'-on (abbreviation: ACRSA). Since the heterocyclic compound has a π-electron excess type heteroaromatic ring and a π-electron deficiency type heteroaromatic ring, it is preferable because it has high electron transport property and hole transport property. A substance in which a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded has strong donor properties of the π-electron-rich heteroaromatic ring and strong acceptability of the π-electron-deficient heteroaromatic ring. This is particularly preferable because the difference between the level of the singlet excited state and the level of the triplet excited state becomes small.

When a thermally activated delayed fluorescent material is used as a host material, it is preferable to use a combination of two types of compounds forming an excitation complex. In this case, it is particularly preferable to use a compound that easily receives electrons and a compound that easily receives holes, which is a combination forming the excitation complex shown above.

Further, the emission colors of the light emitting material contained in the light emitting layer 420 and the light emitting material contained in the light emitting layer 430 are not limited, and may be the same or different. Since the light emitted from each is mixed and taken out of the element, the light emitting element can give white light, for example, when the two emission colors are complementary colors to each other. Considering the reliability of the light emitting element, the emission peak wavelength of the light emitting material contained in the light emitting layer 420 is preferably shorter than that of the light emitting material contained in the light emitting layer 430.

The light emitting unit 441, the light emitting unit 441, and the charge generation layer 445 can be formed by a method such as a vapor deposition method (including a vacuum vapor deposition method), an inkjet method, a coating method, or gravure printing.

The configuration shown in this embodiment can be used in combination with the configurations shown in other embodiments as appropriate.

(Embodiment 3)
In the present embodiment, an example of a light emitting device having a configuration different from that shown in the first and second embodiments will be described below with reference to FIGS. 11 to 14.

<Structure example 1 of light emitting element>
11 (A) and 11 (B) are cross-sectional views showing a light emitting device according to an aspect of the present invention. In addition, in FIGS. 11A and 11B, the same hatch pattern may be used in places having the same function as the reference numerals shown in FIG. 1A, and the reference numerals may be omitted. In addition, parts having the same function may be designated by the same reference numerals, and detailed description thereof may be omitted.

The light emitting element 250 and the light emitting element 252 shown in FIGS. 11A and 11B may be a bottom emission type light emitting element that extracts light to the substrate 200 side, and emits light in a direction opposite to that of the substrate 200. It may be a top emission type light emitting element to be taken out. One aspect of the present invention is not limited to this, and a double-sided injection (dual emission) type light emitting element that extracts the light exhibited by the light emitting element both above and below the substrate 200 may be used.

When the light emitting element 250 and the light emitting element 252 are of the bottom emission type, the electrode 101 preferably has a function of transmitting light. Further, the electrode 102 preferably has a function of reflecting light. Alternatively, when the light emitting element 250 and the light emitting element 252 are of the top emission type, it is preferable that the electrode 101 has a function of reflecting light. Further, the electrode 102 preferably has a function of transmitting light.

The light emitting element 250 and the light emitting element 252 have an electrode 101 and an electrode 102 on the substrate 200. Further, the light emitting layer 123B, the light emitting layer 123G, and the light emitting layer 123R are provided between the electrode 101 and the electrode 102. It also has a hole injection layer 111, a hole transport layer 112, an electron transport layer 118, and an electron injection layer 119.

Further, the light emitting element 252 has a conductive layer 101a, a conductive layer 101b on the conductive layer 101a, and a conductive layer 101c under the conductive layer 101a as a part of the configuration of the electrode 101. That is, the light emitting element 252 has a configuration in which the conductive layer 101a is sandwiched between the conductive layer 101b and the conductive layer 101c.

In the light emitting element 252, the conductive layer 101b and the conductive layer 101c may be formed of different materials or may be formed of the same material. When the electrode 101 has a structure of being sandwiched between the same conductive materials, it is preferable because pattern formation by the etching step becomes easy.

In the light emitting element 252, the conductive layer 101b or the conductive layer 101c may have only one of them.

The conductive layers 101a and 101b and the conductive layer 101c of the electrode 101 can use the same configurations and materials as those of the electrode 101 or the electrode 102 shown in the first embodiment, respectively.

In FIGS. 11A and 11B, the partition wall 140 is provided between the region 221B, the region 221G, and the region 221R sandwiched between the electrode 101 and the electrode 102. The partition wall 140 has an insulating property. The partition wall 140 has an opening that covers the end of the electrode 101 and overlaps with the electrode. By providing the partition wall 140, the electrodes 101 of the substrate 200 in each region can be separated into islands.

The light emitting layer 123B and the light emitting layer 123G may have a region that overlaps with each other in a region that overlaps with the partition wall 140. Alternatively, the light emitting layer 123G and the light emitting layer 123R may have a region that overlaps with each other in a region that overlaps with the partition wall 140. Alternatively, the light emitting layer 123R and the light emitting layer 123B may have a region that overlaps with each other in a region that overlaps with the partition wall 140.

The partition wall 140 may be insulating, and is formed by using an inorganic material or an organic material. Examples of the inorganic material include silicon oxide, silicon oxide nitride, silicon nitride oxide, silicon nitride, aluminum oxide, and aluminum nitride. Examples of the organic material include a photosensitive resin material such as an acrylic resin or a polyimide resin.

Further, it is preferable that the light emitting layer 123R, the light emitting layer 123G, and the light emitting layer 123B have a light emitting material having a function of exhibiting different colors. For example, since the light emitting layer 123R has a light emitting material having a function of exhibiting red, the region 221R exhibits red light emission, and the light emitting layer 123G has a light emitting material having a function of exhibiting green, so that the region 221G is green. The region 221B emits blue light by having a light emitting material having a function of emitting light and causing the light emitting layer 123B to emit blue light. By using the light emitting element 250 or the light emitting element 252 having such a configuration as the pixels of the display device, it is possible to manufacture a display device capable of full-color display. Further, the film thickness of each light emitting layer may be the same or different.

Further, it is preferable that any one or more of the light emitting layers 123B, the light emitting layer 123G, and the light emitting layer 123R have a compound having a delayed fluorescence component due to TTA shown in the first embodiment. By doing so, it is possible to manufacture a light emitting element having good luminous efficiency among the light emitted by the light emitting layer.

The light emitting layer 123B, the light emitting layer 123G, or the light emitting layer 123R may be formed by laminating two or more light emitting layers.

As described above, at least one light emitting layer has a compound having a delayed fluorescence component due to TTA shown in the first embodiment, and the light emitting element 250 or the light emitting element 252 having the light emitting layer is used as a pixel of a display device. This makes it possible to manufacture a display device having high luminous efficiency. That is, the display device having the light emitting element 250 or the light emitting element 252 can reduce the power consumption.

By providing a color filter on the electrode that extracts light, the color purity of the light emitting element 250 and the light emitting element 252 can be improved. Therefore, the color purity of the display device having the light emitting element 250 or the light emitting element 252 can be increased.

Further, by providing a polarizing plate on the electrode that extracts light, it is possible to reduce the reflection of external light by the light emitting element 250 and the light emitting element 252. Therefore, the contrast ratio of the display device having the light emitting element 250 or the light emitting element 252 can be increased.

Regarding other configurations of the light emitting element 250 and the light emitting element 252, the configuration of the light emitting element according to the first embodiment or the second embodiment may be taken into consideration.

<Structure example 2 of light emitting element>
Next, a configuration example different from the light emitting element shown in FIG. 11 will be described below with reference to FIGS. 12A and 12B.

12 (A) and 12 (B) are cross-sectional views showing a light emitting device according to an aspect of the present invention. In addition, in FIGS. 12A and 12B, the same hatch pattern may be used in places having the same function as the reference numerals shown in FIG. 11, and the reference numerals may be omitted. In addition, parts having the same function may be designated by the same reference numerals, and detailed description thereof may be omitted.

12 (A) and 12 (B) are configuration examples of a tandem type light emitting device in which a plurality of light emitting layers are laminated via a charge generation layer 115 between a pair of electrodes. The light emitting element 254 shown in FIG. 12 (A) is a top emission type light emitting element that extracts light in the direction opposite to that of the substrate 200, and the light emitting element 256 shown in FIG. 12 (B) is light toward the substrate 200. It is a bottom injection (bottom emission) type light emitting element. However, one aspect of the present invention is not limited to this, and a double-sided injection (dual emission) type may be used in which the light emitted by the light emitting element is taken out both above and below the substrate 200 on which the light emitting element is formed.

The light emitting element 254 and the light emitting element 256 have an electrode 101, an electrode 102, an electrode 103, and an electrode 104 on the substrate 200. Further, it has a light emitting layer 160, a charge generating layer 115, and a light emitting layer 170 between the electrodes 101 and 102, between the electrodes 102 and 103, and between the electrodes 102 and 104. .. Further, the hole injection layer 111, the hole transport layer 112, the electron transport layer 113, the electron injection layer 114, the hole injection layer 116, the hole transport layer 117, the electron transport layer 118, and the electron injection. It has layers 119 and.

Further, the electrode 101 has a conductive layer 101a and a conductive layer 101b in contact with the conductive layer 101a. Further, the electrode 103 has a conductive layer 103a and a conductive layer 103b in contact with the conductive layer 103a. The electrode 104 has a conductive layer 104a and a conductive layer 104b in contact with the conductive layer 104a.

The light emitting element 254 shown in FIG. 12 (A) and the light emitting element 256 shown in FIG. 12 (B) have a region 222B sandwiched between the electrode 101 and the electrode 102, and a region 222G sandwiched between the electrode 102 and the electrode 103. A partition wall 140 is provided between the electrode 102 and the region 222R sandwiched between the electrode 102 and the electrode 104. The partition wall 140 has an insulating property. The partition wall 140 has an opening that covers the ends of the electrode 101, the electrode 103, and the electrode 104 and overlaps with the electrode. By providing the partition wall 140, the electrodes of the substrate 200 in each region can be separated in an island shape.

Further, the light emitting element 254 and the light emitting element 256 have a substrate 220 having an optical element 224B, an optical element 224G, and an optical element 224R, respectively, in the direction in which the light emitted from the region 222B, the region 222G, and the region 222R is extracted. .. The light emitted from each region is emitted to the outside of the light emitting element via each optical element. That is, the light emitted from the region 222B is emitted through the optical element 224B, the light emitted from the region 222G is emitted through the optical element 224G, and the light emitted from the region 222R is emitted from the optical element 224R. Is ejected through.

Further, the optical element 224B, the optical element 224G, and the optical element 224R have a function of selectively transmitting light having a specific color from the incident light. For example, the light emitted from the region 222B emitted through the optical element 224B becomes light exhibiting blue color, and the light emitted from the region 222G emitted via the optical element 224G becomes light exhibiting green color. The light emitted from the region 222R emitted via the optical element 224R is red.

For example, a colored layer (also referred to as a color filter), a bandpass filter, a multilayer film filter, or the like can be applied to the optical element 224R, the optical element 224G, and the optical element 224B. Further, a color conversion element can be applied to the optical element. The color conversion element is an optical element that converts incident light into light having a wavelength longer than the wavelength of the light. As the color conversion element, it is preferable that the element uses the quantum dot method. By using the quantum dot method, the color reproducibility of the display device can be improved.

A plurality of optical elements may be stacked on the optical element 224R, the optical element 224G, and the optical element 224B. As other optical elements, for example, a circularly polarizing plate or an antireflection film can be provided. If a circular polarizing plate is provided on the side from which the light emitted by the light emitting element of the display device is taken out, it is possible to prevent the phenomenon that the light incident from the outside of the display device is reflected inside the display device and emitted to the outside. it can. Further, if the antireflection film is provided, the external light reflected on the surface of the display device can be weakened. As a result, the light emitted by the display device can be clearly observed.

In FIGS. 12A and 12B, the light emitted from each region via each optical element is the light exhibiting blue (B), the light exhibiting green (G), and the light exhibiting red (R). , Are schematically illustrated by dashed arrows.

Further, a light-shielding layer 223 is provided between the optical elements. The light-shielding layer 223 has a function of blocking light emitted from an adjacent region. The light-shielding layer 223 may not be provided.

The light-shielding layer 223 has a function of suppressing reflection of external light. Alternatively, the light-shielding layer 223 has a function of preventing color mixing of light emitted from adjacent light emitting elements. As the light-shielding layer 223, a metal, a resin containing a black pigment, carbon black, a metal oxide, a composite oxide containing a solid solution of a plurality of metal oxides, or the like can be used.

As the substrate 220 and the substrate 200 having the optical element, the first embodiment may be taken into consideration.

≪Microcavity structure≫
Further, the light emitting element 254 and the light emitting element 256 have a microcavity structure.

The light emitted from the light emitting layer 160 and the light emitting layer 170 resonates between the pair of electrodes (for example, the electrode 101 and the electrode 102). Further, the light emitting layer 160 and the light emitting layer 170 are formed at positions where the light having a desired wavelength is strengthened among the emitted light. For example, the light is emitted from the light emitting layer 160 by adjusting the optical distance from the reflection region of the electrode 101 to the light emitting region of the light emitting layer 160 and the optical distance from the reflection region of the electrode 102 to the light emitting region of the light emitting layer 160. It is possible to intensify the light having a desired wavelength among the light. Further, by adjusting the optical distance from the reflection region of the electrode 101 to the light emitting region of the light emitting layer 170 and the optical distance from the reflection region of the electrode 102 to the light emitting region of the light emitting layer 170, the light is emitted from the light emitting layer 170. It is possible to intensify the light having a desired wavelength among the light. That is, in the case of a tandem type light emitting element in which a plurality of light emitting layers (here, the light emitting layer 160 and the light emitting layer 170) are laminated via the charge generation layer 115, the optical distances of the light emitting layer 160 and the light emitting layer 170 are optimized. It is preferable to make it.

Further, in the light emitting element 254 and the light emitting element 256, the light emitting layer 160 and the light emitting layer 170 are presented by adjusting the thickness of the conductive layer (conductive layer 101b, conductive layer 103b, and conductive layer 104b) in each region. It is possible to intensify the light having a desired wavelength among the light. The light emitted from the light emitting layer 160 and the light emitting layer 170 may be strengthened by making the thickness of at least one of the hole injection layer 111 and the hole transport layer 112 different in each region.

For example, in the electrodes 101 to 104, when the refractive index of the conductive material having a function of reflecting light is smaller than the refractive index of the light emitting layer 160 or the light emitting layer 170, the film of the conductive layer 101b of the electrode 101. The thickness is adjusted so that the optical distance between the electrode 101 and the electrode 102 is mλ _B / 2 (m is a natural number, and λ _B is the wavelength of light to be strengthened in the region 222B). Similarly, the film thickness of the conductive layer 103b of the electrode 103 is such that the optical distance between the electrode 103 and the electrode 102 is m'λ _G / 2 (m'is a natural number, λ _G is the wavelength of light that enhances in the region 222 _G. , Represent each). Further, the film thickness of the conductive layer 104b of the electrode 104 is such that the optical distance between the electrode 104 and the electrode 102 is m ″ λ _R / 2 (m ″ is a natural number, and λ _R is the wavelength of light that is enhanced in the region 222 _R. , Representing each).

As described above, by providing the microcavity structure and adjusting the optical distance between the pair of electrodes in each region, it is possible to suppress light scattering and light absorption in the vicinity of each electrode and realize high light extraction efficiency. Can be done. In the above configuration, the conductive layer 101b, the conductive layer 103b, and the conductive layer 104b preferably have a function of transmitting light. Further, the materials constituting the conductive layer 101b, the conductive layer 103b, and the conductive layer 104b may be the same as each other or may be different from each other. Further, the conductive layer 101b, the conductive layer 103b, and the conductive layer 104b may each have a configuration in which two or more layers are laminated.

Since the light emitting element 254 shown in FIG. 12 (A) is a top injection type light emitting element, it is preferable that the conductive layer 101a, the conductive layer 103a, and the conductive layer 104a have a function of reflecting light. Further, the electrode 102 preferably has a function of transmitting light and a function of reflecting light.

Further, since the light emitting element 256 shown in FIG. 12B is a bottom surface emitting type light emitting element, the conductive layer 101a, the conductive layer 103a, and the conductive layer 104a have a function of transmitting light and a function of reflecting light. , It is preferable to have. Further, the electrode 102 preferably has a function of reflecting light.

Further, in the light emitting element 254 and the light emitting element 256, the same material may be used for the conductive layer 101a, the conductive layer 103a, or the conductive layer 104a, or different materials may be used. When the same material is used for the conductive layer 101a, the conductive layer 103a, and the conductive layer 104a, the manufacturing cost of the light emitting element 254 and the light emitting element 256 can be reduced. The conductive layer 101a, the conductive layer 103a, and the conductive layer 104a may each have a configuration in which two or more layers are laminated.

Further, it is preferable to use a compound having a delayed fluorescence component due to TTA shown in the first embodiment in at least one light emitting layer of the light emitting layer 160 or the light emitting layer 170. By doing so, a light emitting element exhibiting high luminous efficiency can be manufactured. In particular, in the region 222B, a light emitting element having a blue emission spectrum peak with good luminous efficiency can be used.

Further, the light emitting layer 160 and the light emitting layer 170 may each have a configuration in which two layers are laminated, such as the light emitting layer 170a and the light emitting layer 170b. By using two types of light emitting materials having a function of exhibiting different colors, a first compound and a second compound, for the two light emitting layers, a plurality of light emission can be obtained at the same time. In particular, it is preferable to select a light emitting material to be used for each light emitting layer so that the light emitting layer 160 and the light emitting layer 170 emit white light.

Further, the light emitting layer 160 or the light emitting layer 170 may each have a configuration in which three or more layers are laminated, and may include a layer having no light emitting material.

As described above, at least one light emitting layer has a compound having a delayed fluorescence component due to TTA shown in the first embodiment, and the light emitting element 254 or the light emitting element 256 having the light emitting layer is used as a pixel of a display device. This makes it possible to manufacture a display device having high luminous efficiency. That is, the display device having the light emitting element 254 or the light emitting element 256 can reduce the power consumption.

Regarding other configurations of the light emitting element 254 and the light emitting element 256, the configuration of the light emitting element 250 or the light emitting element 252, or the configuration of the light emitting element shown in the first embodiment or the second embodiment may be taken into consideration.

<Components of light emitting layer>
Next, the details of the components of the light emitting layer in the light emitting elements shown in FIGS. 11 and 12 will be described below.

The light emitting layer 123B, the light emitting layer 123G, the light emitting layer 123R, the light emitting layer 160 or the light emitting layer 170 is a first guest material having a function of exhibiting at least one light emission selected from purple, blue, and blue-green. It has a certain luminescent substance. Alternatively, it has a luminescent substance which is a second guest material having a function of exhibiting at least one luminescence selected from green, yellowish green, yellow, orange, and red. Further, each light emitting layer is composed of one or both of an electron transporting material and a hole transporting material in addition to the light emitting substance which is the first guest material. Further, each light emitting layer is composed of one or both of an electron transporting material and a hole transporting material in addition to a light emitting substance which is a second guest material.

Further, as the first guest material, a luminescent substance having a function of converting singlet excitation energy into light emission can be used. Further, as the second guest material, a luminescent substance having a function of converting singlet excitation energy into luminescence or a luminescent substance having a function of converting triplet excitation energy into luminescence can be used. Examples of the luminescent substance include the following.

Examples of the luminescent substance that converts the singlet excitation energy into light emission include a substance that can be used for the guest material 132 shown in the first embodiment.

Further, as a luminescent substance that converts triplet excitation energy into light emission, for example, a substance that emits phosphorescence can be mentioned.

The material that can be used as the host material for the light emitting layer is not particularly limited, but may be used, for example, in the host material 131, the organic compound 431_1 and the organic compound 431_2 shown in the first and second embodiments. Examples of substances that can be produced. From these and various substances, one or a plurality of substances having an energy gap larger than the energy gap of the luminescent material may be selected and used. When the luminescent material is a substance that emits phosphorescence, select a material having a triplet excitation energy larger than the triplet excitation energy (energy difference between the base state and the triplet excited state) of the luminescent material as the host material. Just do it.

When a plurality of materials are used as the host material of the light emitting layer, it is preferable to use two kinds of compounds forming an excitation complex in combination. In this case, various carrier transporting materials can be appropriately used, but in order to efficiently form an excited complex, a compound that easily receives electrons (a material having electron transporting property) and a compound that easily receives holes (holes). It is particularly preferable to combine it with a material having transportability).

This is because, when a material having electron transporting property and a material having hole transporting property are combined to form a host material for forming an excited complex, the mixing ratio of the material having electron transporting property and the material having hole transporting property is used. By adjusting the above, it becomes easy to optimize the carrier balance of holes and electrons in the light emitting layer. By optimizing the carrier balance of holes and electrons in the light emitting layer, it is possible to suppress the bias of the region where the recombination of electrons and holes occurs in the light emitting layer. By suppressing the bias of the region where recombination occurs, the reliability of the light emitting element can be improved.

As a compound that easily receives electrons (a material having an electron transporting property), a π-electron-deficient heteroaromatic compound such as a nitrogen-containing heteroaromatic compound or a metal complex can be used. Among them, a heterocyclic compound having a diazine skeleton and a triazine skeleton and a heterocyclic compound having a pyridine skeleton are preferable because they have good reliability. In particular, a heterocyclic compound having a diazine (pyrimidine or pyrazine) skeleton and a triazine skeleton has high electron transport property and contributes to reduction of driving voltage.

As a compound that easily receives holes (a material having a hole transporting property), a π-electron excess type heteroaromatic (for example, a carbazole derivative or an indole derivative) or an aromatic amine can be preferably used. Further, a compound having a thiophene skeleton and a compound having a furan skeleton can be mentioned. Among them, a compound having an aromatic amine skeleton and a compound having a carbazole skeleton are preferable because they have good reliability, high hole transportability, and contribute to reduction of driving voltage.

The combination of host materials forming the excitation complex is not limited to the above-mentioned compounds, but is a combination capable of transporting carriers and forming an excitation complex, and the emission of the excitation complex is absorption of the luminescent substance. Other materials may be used as long as they overlap with the absorption band on the longest wavelength side in the spectrum (absorption corresponding to the transition from the single-term ground state to the single-term excited state of the luminescent material).

Further, a thermal activated delayed fluorescent material may be used as the light emitting material or the host material of the light emitting layer.

<Method of manufacturing light emitting element>
Next, a method for manufacturing the light emitting device according to one aspect of the present invention will be described below with reference to FIGS. 13 and 14. Here, a method of manufacturing the light emitting element 254 shown in FIG. 12A will be described.

13 and 14 are cross-sectional views for explaining a method of manufacturing a light emitting device according to an aspect of the present invention.

The method for manufacturing the light emitting device 254 described below has seven steps from the first to the seventh.

≪First step≫
In the first step, the electrodes of the light emitting element (specifically, the conductive layer 101a forming the electrode 101, the conductive layer 103a forming the electrode 103, and the conductive layer 104a forming the electrode 104) are placed on the substrate 200. This is a step of forming (see FIG. 13 (A)).

In the present embodiment, a conductive layer having a function of reflecting light is formed on the substrate 200, and the conductive layer is processed into a desired shape to form a conductive layer 101a, a conductive layer 103a, and a conductive layer 104a. To form. As the conductive layer having a function of reflecting the light, an alloy film of silver, palladium and copper (also referred to as Ag-Pd-Cu film or APC) is used. As described above, by forming the conductive layer 101a, the conductive layer 103a, and the conductive layer 104a through the steps of processing the same conductive layer, the manufacturing cost can be reduced, which is preferable.

Before the first step, a plurality of transistors may be formed on the substrate 200. Further, the plurality of transistors and the conductive layer 101a, the conductive layer 103a, and the conductive layer 104a may be electrically connected to each other.

≪Second step≫
In the second step, the conductive layer 101b having a function of transmitting light on the conductive layer 101a constituting the electrode 101 and the conductive layer 103b having a function of transmitting light on the conductive layer 103a constituting the electrode 103 are provided. This is a step of forming a conductive layer 104b having a function of transmitting light on the conductive layer 104a constituting the electrode 104 (see FIG. 13B).

In the present embodiment, the conductive layers 101b, 103b, and 104b having the function of transmitting light are formed on the conductive layers 101a, 103a, and 104a having the function of reflecting light, respectively, and these conductive layers are formed. Is processed into a desired shape to form an electrode 101, an electrode 103, and an electrode 104. An ITSO film is used as the conductive layers 101b, 103b, and 104b.

The conductive layers 101b, 103b, and 104b having a function of transmitting light may be formed in a plurality of times. By forming the conductive layers in a plurality of times, the conductive layers 101b, 103b, and 104b can be formed with a film thickness having a microcavity structure suitable for each region.

≪Third step≫
The third step is a step of forming a partition wall 140 that covers the end portions of each electrode of the light emitting element (see FIG. 13C).

The partition wall 140 has an opening so as to overlap the electrodes. The conductive film exposed by the opening functions as an anode of the light emitting element. In this embodiment, a polyimide resin is used as the partition wall 140.

In the first to third steps, since there is no risk of damaging the EL layer (layer containing an organic compound), various film forming methods and microfabrication techniques can be applied. In the present embodiment, a reflective conductive layer is formed by using a sputtering method, the conductive layer is patterned by using a lithography method, and then the conductive layer is formed by using a dry etching method or a wet etching method. Is processed into an island shape to form a conductive layer 101a forming the electrode 101, a conductive layer 103a forming the electrode 103, and a conductive layer 104a forming the electrode 104. Then, a transparent conductive film is formed by using a sputtering method, a pattern is formed on the transparent conductive film by using a lithography method, and then the transparent conductive film is formed by using a wet etching method. It is processed into an island shape to form an electrode 101, an electrode 103, and an electrode 104.

≪4th step≫
The fourth step is a step of forming the hole injection layer 111, the hole transport layer 112, the light emitting layer 170, the electron transport layer 113, the electron injection layer 114, and the charge generation layer 115 (see FIG. 14 (A)). ).

The hole injection layer 111 can be formed by co-depositing a hole transporting material and a material containing an acceptor substance. The co-evaporation is a vaporization method in which a plurality of different substances are simultaneously evaporated from different evaporation sources. Further, the hole transport layer 112 can be formed by depositing a hole transport material.

The light emitting layer 170 can be formed by depositing a second guest material exhibiting at least one light emission selected from green, yellowish green, yellow, orange, and red. As the second guest material, a luminescent organic compound exhibiting fluorescence or phosphorescence can be used. Further, the luminescent organic compound may be vapor-deposited alone, or may be mixed with another substance and vapor-deposited. Further, a luminescent organic compound may be used as a guest material, and the guest material may be dispersed and vapor-deposited on a host material having a larger excitation energy than the guest material. Further, it is preferable that the light emitting layer 170 is composed of two layers, a light emitting layer 170a and a light emitting layer 170b. In that case, it is preferable that the light emitting layer 170a and the light emitting layer 170b each have a light emitting substance exhibiting different light emitting colors.

The electron transport layer 113 can be formed by depositing a substance having a high electron transport property. Further, the electron injection layer 114 can be formed by depositing a substance having a high electron injection property.

The charge generation layer 115 is formed by depositing a material in which an electron acceptor is added to a hole transporting material or a material in which an electron donor is added to an electron transporting material. Can be done.

≪Fifth step≫
The fifth step is a step of forming the hole injection layer 116, the hole transport layer 117, the light emitting layer 160, the electron transport layer 118, the electron injection layer 119, and the electrode 102 (see FIG. 14B).

The hole injection layer 116 can be formed by the same material and the same method as the hole injection layer 111 shown above. Further, the hole transport layer 117 can be formed by the same material and the same method as the hole transport layer 112 shown above.

The light emitting layer 160 can be formed by depositing a first guest material exhibiting at least one light emission selected from purple, blue, and blue-green. As the first guest material, a fluorescent organic compound can be used. Further, the fluorescent organic compound may be vapor-deposited alone, or may be mixed with other materials and vapor-deposited. Further, a fluorescent organic compound may be used as a guest material, and the guest material may be dispersed and vapor-deposited on a host material having a larger excitation energy than the guest material.

The electron transport layer 118 can be formed by depositing a substance having a high electron transport property. Further, the electron injection layer 119 can be formed by depositing a substance having a high electron injection property.

The electrode 102 can be formed by laminating a conductive film having a reflective property and a conductive film having a translucent property. Further, the electrode 102 may have a single-layer structure or a laminated structure.

Through the above steps, a light emitting element having a region 222B, a region 222G, and a region 222R is formed on the substrate 200 on the electrode 101, the electrode 103, and the electrode 104, respectively.

≪6th step≫
The sixth step is a step of forming the light-shielding layer 223, the optical element 224B, the optical element 224G, and the optical element 224R on the substrate 220 (see FIG. 14C).

As the light-shielding layer 223, a resin film containing a black pigment is formed in a desired region. After that, the optical element 224B, the optical element 224G, and the optical element 224R are formed on the substrate 220 and the light shielding layer 223. As the optical element 224B, a resin film containing a blue pigment is formed in a desired region. Further, as the optical element 224G, a resin film containing a green pigment is formed in a desired region. Further, as the optical element 224R, a resin film containing a red pigment is formed in a desired region.

≪7th step≫
In the seventh step, the light emitting element formed on the substrate 200 and the light-shielding layer 223, the optical element 224B, the optical element 224G, and the optical element 224R formed on the substrate 220 are bonded together to form a sealing material. This is a step of sealing by using (not shown).

By the above steps, the light emitting element 254 shown in FIG. 12 (A) can be formed.

The configuration shown in this embodiment can be used in combination with the configurations shown in other embodiments as appropriate.

(Embodiment 4)
In the present embodiment, the display device of one aspect of the present invention will be described with reference to FIGS. 15 to 21.

<Display device configuration example 1>
15 (A) is a top view showing the display device 600, and FIG. 15 (B) is a cross-sectional view taken along the alternate long and short dash line AB and the alternate long and short dash line CD of FIG. 15 (A). The display device 600 includes a drive circuit unit (signal line drive circuit unit 601 and a scanning line drive circuit unit 603), and a pixel unit 602. The signal line drive circuit unit 601, the scanning line drive circuit unit 603, and the pixel unit 602 have a function of controlling the light emission of the light emitting element.

Further, the display device 600 includes an element substrate 610, a sealing substrate 604, a sealing material 605, a region 607 surrounded by the sealing material 605, a routing wiring 608, and an FPC 609.

The routing wiring 608 is a wiring for transmitting signals input to the signal line drive circuit unit 601 and the scanning line drive circuit unit 603, and is a video signal, a clock signal, a start signal, and a video signal, a clock signal, and a start signal from the FPC 609 which is an external input terminal. Receives a reset signal, etc. Although only the FPC 609 is shown here, a printed wiring board (PWB: Printed Wiring Board) may be attached to the FPC 609.

Further, the signal line drive circuit unit 601 forms a CMOS circuit in which an N-channel type transistor 623 and a P-channel type transistor 624 are combined. As the signal line drive circuit unit 601 or the scanning line drive circuit unit 603, various CMOS circuits, MOSFET circuits, or NMOS circuits can be used. Further, in the present embodiment, a display device in which a driver having a drive circuit unit formed on a substrate and a pixel are provided on the same surface is shown, but it is not always necessary, and the drive circuit unit is not on the substrate but externally. It can also be formed into.

Further, the pixel unit 602 has a transistor 611 for switching, a transistor 612 for current control, and a lower electrode 613 electrically connected to the drain of the transistor 612 for current control. A partition wall 614 is formed so as to cover the end portion of the lower electrode 613. As the partition wall 614, a positive photosensitive acrylic resin film can be used.

Further, in order to improve the covering property, a curved surface having a curvature is formed at the upper end portion or the lower end portion of the partition wall 614. For example, when positive photosensitive acrylic is used as the material of the partition wall 614, it is preferable that only the upper end portion of the partition wall 614 has a curved surface having a radius of curvature (0.2 μm or more and 3 μm or less). Further, as the partition wall 614, either a negative type photosensitive resin or a positive type photosensitive resin can be used.

The structure of the transistors (transistors 611, 612, 623, 624) is not particularly limited. For example, a staggered transistor may be used. Further, the polarity of the transistor is not particularly limited, and a structure having N-channel type and P-channel type transistors and a structure consisting of only one of N-channel type transistor and P-channel type transistor may be used. .. Further, the crystallinity of the semiconductor film used for the transistor is not particularly limited. For example, an amorphous semiconductor film or a crystalline semiconductor film can be used. Further, as the semiconductor material, a group 14 (silicon or the like) semiconductor, a compound semiconductor (including an oxide semiconductor), an organic semiconductor or the like can be used. As the transistor, for example, it is preferable to use an oxide semiconductor having an energy gap of 2 eV or more, preferably 2.5 eV or more, more preferably 3 eV or more, because the off-current of the transistor can be reduced. Examples of the oxide semiconductor include In-Ga oxide, In-M-Zn oxide (M is Al, Ga, yttrium (Y), zirconium (Zr), lanthanum (La), cerium (Ce), Sn, Hafnium (Hf), or neodymium (Nd)) and the like.

An EL layer 616 and an upper electrode 617 are formed on the lower electrode 613, respectively. The lower electrode 613 functions as an anode, and the upper electrode 617 functions as a cathode.

Further, the EL layer 616 is formed by various methods such as a vapor deposition method using a vapor deposition mask, an inkjet method, and a spin coating method. Further, the other material constituting the EL layer 616 may be a low molecular weight compound or a high molecular weight compound (including an oligomer and a dendrimer).

The light emitting element 618 is formed by the lower electrode 613, the EL layer 616, and the upper electrode 617. The light emitting element 618 is a light emitting element having the configuration of the first embodiment or the second embodiment. When a plurality of light emitting elements are formed, the pixel unit may include both the light emitting element according to the first embodiment or the second embodiment and the light emitting element having other configurations.

Further, by bonding the sealing substrate 604 to the element substrate 610 with the sealing material 605, the light emitting element 618 is provided in the region 607 surrounded by the element substrate 610, the sealing substrate 604, and the sealing material 605. ing. In addition, the region 607 is filled with a filler, and in addition to the case where an inert gas (nitrogen, argon, etc.) is filled, the region 607 is filled with an ultraviolet curable resin or a thermosetting resin that can be used for the sealing material 605. For example, PVC (polyvinyl chloride) resin, acrylic resin, polyimide resin, epoxy resin, silicone resin, PVB (polyvinyl chloride) resin, or EVA (ethylene vinyl acetate) resin may be used. Can be used. If a recess is formed in the sealing substrate and a desiccant is provided therein, deterioration due to the influence of moisture can be suppressed, which is a preferable configuration.

Further, the optical element 621 is provided below the sealing substrate 604 so as to overlap with the light emitting element 618. Further, a light-shielding layer 622 is provided below the sealing substrate 604. The optical element 621 and the light-shielding layer 622 may have the same configurations as the optical element and the light-shielding layer shown in the third embodiment, respectively.

It is preferable to use an epoxy resin or glass frit for the sealing material 605. Further, it is desirable that these materials are materials that do not easily permeate water and oxygen as much as possible. Further, as a material used for the sealing substrate 604, in addition to a glass substrate and a quartz substrate, a plastic substrate made of FRP (Fiber Reinforced Plastics), PVF (polyvinyl fluoride), polyester, acrylic or the like can be used.

As described above, the display device having the light emitting element and the optical element according to the first to third embodiments can be obtained.

<Display device configuration example 2>
Next, another example of the display device will be described with reference to FIGS. 16A and 16B. 16 (A) and 16 (B) and 17 are cross-sectional views of a display device according to an aspect of the present invention.

In FIG. 16A, the substrate 1001, the underlying insulating film 1002, the gate insulating film 1003, the gate electrodes 1006, 1007, 1008, the first interlayer insulating film 1020, the second interlayer insulating film 1021, the peripheral portion 1042, and the pixel portion are shown. 1040, drive circuit unit 1041, lower electrode 1024R, 1024G, 1024B of light emitting element, partition wall 1025, EL layer 1028, upper electrode 1026 of light emitting element, sealing layer 1029, sealing substrate 1031, sealing material 1032 and the like are illustrated. There is.

Further, in FIG. 16A, as an example of the optical element, a colored layer (red colored layer 1034R, green colored layer 1034G, and blue colored layer 1034B) is provided on the transparent base material 1033. Further, a light-shielding layer 1035 may be further provided. The transparent base material 1033 provided with the coloring layer and the light-shielding layer is aligned and fixed to the substrate 1001. The colored layer and the light-shielding layer are covered with the overcoat layer 1036. Further, in FIG. 16A, since the light transmitted through the colored layer is red, green, and blue, an image can be expressed by pixels of three colors.

In FIG. 16B, as an example of the optical element, a colored layer (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B) is placed between the gate insulating film 1003 and the first interlayer insulating film 1020. An example of forming in is shown. As described above, the colored layer may be provided between the substrate 1001 and the sealing substrate 1031.

In FIG. 17, as an example of the optical element, a colored layer (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B) is placed between the first interlayer insulating film 1020 and the second interlayer insulating film 1021. An example of forming in is shown. As described above, the colored layer may be provided between the substrate 1001 and the sealing substrate 1031.

Further, in the display device described above, the display device has a structure that extracts light to the substrate 1001 side on which the transistor is formed (bottom emission type), but has a structure that extracts light to the sealing substrate 1031 side (top emission type). ) May be used as a display device.

<Display device configuration example 3>
An example of a cross-sectional view of the top emission type display device is shown in FIGS. 18A and 18B. 18 (A) and 18 (B) are cross-sectional views for explaining the display device of one aspect of the present invention, and the drive circuit unit 1041 and the peripheral unit 1042 shown in FIGS. 16 (A) and 17 are omitted. Is illustrated.

In this case, the substrate 1001 can be a substrate that does not transmit light. Until the connection electrode for connecting the transistor and the anode of the light emitting element is manufactured, it is formed in the same manner as the bottom emission type display device. After that, a third interlayer insulating film 1037 is formed so as to cover the electrode 1022. This insulating film may play a role of flattening. The third interlayer insulating film 1037 can be formed by using the same material as the second interlayer insulating film and various other materials.

The lower electrodes 1024R, 1024G, and 1024B of the light emitting element are used as anodes here, but may be cathodes. Further, in the case of the top emission type display device as shown in FIGS. 18A and 18B, it is preferable that the lower electrodes 1024R, 1024G and 1024B have a function of reflecting light. Further, the upper electrode 1026 is provided on the EL layer 1028. The upper electrode 1026 has a function of reflecting light and a function of transmitting light, and adopts a microcavity structure between the lower electrodes 1024R, 1024G, 1024B and the upper electrode 1026 to obtain light intensity at a specific wavelength. It is preferable to increase it.

In the top emission structure as shown in FIG. 18A, the sealing is performed by the sealing substrate 1031 provided with the colored layers (red colored layer 1034R, green colored layer 1034G, and blue colored layer 1034B). it can. The sealing substrate 1031 may be provided with a light-shielding layer 1035 so as to be located between the pixels. It is preferable to use a translucent substrate for the sealing substrate 1031.

Further, in FIG. 18A, a plurality of light emitting elements and a configuration in which a colored layer is provided on each of the plurality of light emitting elements are illustrated, but the present invention is not limited to this. For example, as shown in FIG. 18B, a red colored layer 1034R and a blue colored layer 1034B are provided without providing a green colored layer, and full-color display is performed in three colors of red, green, and blue. It may be configured. As shown in FIG. 18A, when the light emitting element and the light emitting element are each provided with a colored layer, the effect of suppressing the reflection of external light can be obtained. On the other hand, as shown in FIG. 18B, when the light emitting element and the red colored layer and the blue colored layer are provided without providing the green colored layer, the light is emitted from the green light emitting element. Since the energy loss of the light is small, it has the effect of reducing power consumption.

<Display device configuration example 4>
The display device shown above has a configuration having sub-pixels of three colors (red, green, blue), but sub-pixels of four colors (red, green, blue, yellow, or red, green, blue, white). It may be configured to have. 19 to 21 are configurations of a display device having lower electrodes 1024R, 1024G, 1024B, and 1024Y. 19 (A) and 20 (B) and 20 are display devices having a structure (bottom emission type) in which light is extracted to the substrate 1001 side on which the transistor is formed, and FIGS. 21 (A) and 21 (B) are sealed. It is a display device having a structure (top emission type) that extracts light emission on the substrate 1031 side.

FIG. 19A is an example of a display device in which optical elements (colored layer 1034R, colored layer 1034G, colored layer 1034B, colored layer 1034Y) are provided on a transparent base material 1033. Further, FIG. 19B shows a display device in which an optical element (colored layer 1034R, colored layer 1034G, colored layer 1034B, colored layer 1034Y) is formed between the gate insulating film 1003 and the first interlayer insulating film 1020. This is an example. Further, FIG. 20 shows a display device in which an optical element (colored layer 1034R, colored layer 1034G, colored layer 1034B, colored layer 1034Y) is formed between the first interlayer insulating film 1020 and the second interlayer insulating film 1021. This is an example.

The colored layer 1034R has a function of transmitting red light, the colored layer 1034G has a function of transmitting green light, and the colored layer 1034B has a function of transmitting blue light. Further, the colored layer 1034Y has a function of transmitting yellow light or a function of transmitting a plurality of light selected from blue, green, yellow, and red. When the colored layer 1034Y has a function of transmitting a plurality of lights selected from blue, green, yellow, and red, the light transmitted through the colored layer 1034Y may be white. Since the light emitting element exhibiting yellow or white light emission has high luminous efficiency, the display device having the colored layer 1034Y can reduce the power consumption.

Further, in the top emission type display device shown in FIG. 21, the light emitting element having the lower electrode 1024Y also has a microcavity structure with the upper electrode 1026, similarly to the display device shown in FIG. 18 (A). The configuration is preferred. Further, in the display device of FIG. 21 (A), the display device is sealed with a sealing substrate 1031 provided with colored layers (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B, and yellow colored layer 1034Y). It can be performed.

The emission emitted through the microcavity and the yellow colored layer 1034Y is emission having an emission spectrum in the yellow region. Since yellow is a color having high luminosity factor, a light emitting element exhibiting yellow light emission has high luminous efficiency. That is, the display device having the configuration of FIG. 21 (A) can reduce the power consumption.

Further, in FIG. 21A, a plurality of light emitting elements and a configuration in which a colored layer is provided on each of the plurality of light emitting elements are illustrated, but the present invention is not limited to this. For example, as shown in FIG. 21 (B), a red colored layer 1034R, a green colored layer 1034G, and a blue colored layer 1034B are provided without providing the yellow colored layer, and red, green, blue, and yellow are provided. The full-color display may be performed with the four colors of, or the four colors of red, green, blue, and white. As shown in FIG. 21 (A), when the light emitting element and the light emitting element are each provided with a colored layer, the effect of suppressing the reflection of external light can be obtained. On the other hand, as shown in FIG. 21 (B), when the light emitting element and the yellow colored layer are not provided but the red colored layer, the green colored layer, and the blue colored layer are provided, yellow or yellow or Since the energy loss of the light emitted from the white light emitting element is small, the power consumption can be reduced.

The configuration shown in the present embodiment can be appropriately combined with other embodiments or other configurations in the present embodiment.

(Embodiment 5)
In the present embodiment, the display device having the light emitting element of one aspect of the present invention will be described with reference to FIGS. 22 to 24.

Note that FIG. 22A is a block diagram illustrating a display device according to an aspect of the present invention, and FIG. 22B describes a pixel circuit included in the display device according to an aspect of the present invention. It is a circuit diagram.

<Explanation of display device>
The display device shown in FIG. 22 (A) has a region having pixels of a display element (hereinafter referred to as a pixel unit 802) and a circuit unit (hereinafter referred to as a circuit unit) arranged outside the pixel unit 802 and having a circuit for driving the pixels. , Drive circuit unit 804), a circuit having an element protection function (hereinafter referred to as protection circuit 806), and a terminal unit 807. The protection circuit 806 may not be provided.

It is desirable that a part or all of the drive circuit unit 804 is formed on the same substrate as the pixel unit 802. As a result, the number of parts and the number of terminals can be reduced. When a part or all of the drive circuit unit 804 is not formed on the same substrate as the pixel unit 802, a part or all of the drive circuit unit 804 is formed by COG or TAB (Tape Implemented Bonding). Can be implemented.

The pixel unit 802 has a circuit (hereinafter referred to as a pixel circuit 801) for driving a plurality of display elements arranged in the X row (X is a natural number of 2 or more) and the Y column (Y is a natural number of 2 or more). The drive circuit unit 804 supplies a circuit that outputs a signal for selecting a pixel (scanning signal) (hereinafter referred to as a scanning line drive circuit 804a) and a signal (data signal) for driving a pixel display element. It has a drive circuit such as a circuit (hereinafter, signal line drive circuit 804b).

The scanning line drive circuit 804a has a shift register and the like. The scanning line drive circuit 804a receives a signal for driving the shift register via the terminal unit 807 and outputs the signal. For example, the scanning line drive circuit 804a receives a start pulse signal, a clock signal, and the like, and outputs a pulse signal. The scanning line drive circuit 804a has a function of controlling the potential of the wiring (hereinafter, referred to as scanning lines GL_1 to GL_X) to which the scanning signal is given. A plurality of scanning line driving circuits 804a may be provided, and the scanning lines GL_1 to GL_X may be divided and controlled by the plurality of scanning line driving circuits 804a. Alternatively, the scanning line drive circuit 804a has a function of being able to supply an initialization signal. However, the present invention is not limited to this, and the scanning line drive circuit 804a can also supply another signal.

The signal line drive circuit 804b has a shift register and the like. In the signal line drive circuit 804b, in addition to the signal for driving the shift register, a signal (image signal) that is the source of the data signal is input via the terminal unit 807. The signal line drive circuit 804b has a function of generating a data signal to be written in the pixel circuit 801 based on the image signal. Further, the signal line drive circuit 804b has a function of controlling the output of a data signal according to a pulse signal obtained by inputting a start pulse, a clock signal, or the like. Further, the signal line drive circuit 804b has a function of controlling the potential of the wiring (hereinafter referred to as data lines DL_1 to DL_Y) to which the data signal is given. Alternatively, the signal line drive circuit 804b has a function of being able to supply an initialization signal. However, the present invention is not limited to this, and the signal line drive circuit 804b can also supply another signal.

The signal line drive circuit 804b is configured by using, for example, a plurality of analog switches. The signal line drive circuit 804b can output a time-division signal of the image signal as a data signal by sequentially turning on a plurality of analog switches. Further, the signal line drive circuit 804b may be configured by using a shift register or the like.

In each of the plurality of pixel circuits 801 the pulse signal is input via one of the plurality of scanning lines GL to which the scanning signal is given, and the data signal is transmitted through one of the plurality of data line DLs to which the data signal is given. Entered. Further, in each of the plurality of pixel circuits 801 the writing and holding of data of the data signal is controlled by the scanning line driving circuit 804a. For example, in the pixel circuit 801 of the mth row and nth column, a pulse signal is input from the scanning line drive circuit 804a via the scanning line GL_m (m is a natural number of X or less), and the data line DL_n corresponds to the potential of the scanning line GL_m. A data signal is input from the signal line drive circuit 804b via (n is a natural number equal to or less than Y).

The protection circuit 806 shown in FIG. 22A is connected to, for example, the scanning line GL, which is the wiring between the scanning line driving circuit 804a and the pixel circuit 801. Alternatively, the protection circuit 806 is connected to the data line DL, which is the wiring between the signal line drive circuit 804b and the pixel circuit 801. Alternatively, the protection circuit 806 can be connected to the wiring between the scanning line drive circuit 804a and the terminal portion 807. Alternatively, the protection circuit 806 can be connected to the wiring between the signal line drive circuit 804b and the terminal portion 807. The terminal portion 807 is a portion provided with a terminal for inputting a power supply, a control signal, and an image signal from an external circuit to the display device.

The protection circuit 806 is a circuit that makes the wiring connected to the protection circuit 806 conductive when a potential outside a certain range is applied to the wiring.

As shown in FIG. 22 (A), by providing protection circuits 806 in the pixel unit 802 and the drive circuit unit 804, respectively, the resistance of the display device to overcurrent generated by ESD (Electrostatic Discharge) or the like is enhanced. be able to. However, the configuration of the protection circuit 806 is not limited to this, and for example, the protection circuit 806 may be connected to the scanning line drive circuit 804a, or the protection circuit 806 may be connected to the signal line drive circuit 804b. Alternatively, the protection circuit 806 may be connected to the terminal portion 807.

Further, FIG. 22A shows an example in which the drive circuit unit 804 is formed by the scanning line drive circuit 804a and the signal line drive circuit 804b, but the configuration is not limited to this. For example, as a configuration in which only the scanning line drive circuit 804a is formed and a substrate on which a separately prepared signal line drive circuit is formed (for example, a drive circuit board formed of a single crystal semiconductor film or a polycrystalline semiconductor film) is mounted. Is also good.

<Pixel circuit configuration example>
The plurality of pixel circuits 801 shown in FIG. 22 (A) can have the configuration shown in FIG. 22 (B), for example.

The pixel circuit 801 shown in FIG. 22B includes transistors 852 and 854, a capacitance element 862, and a light emitting element 872.

One of the source electrode and the drain electrode of the transistor 852 is electrically connected to the wiring (data line DL_n) to which the data signal is given. Further, the gate electrode of the transistor 852 is electrically connected to the wiring (scanning line GL_m) to which the gate signal is given.

The transistor 852 has a function of controlling the writing of data of the data signal.

One of the pair of electrodes of the capacitive element 862 is electrically connected to the wiring to which the potential is applied (hereinafter referred to as the potential supply line VL_a), and the other is electrically connected to the other of the source electrode and the drain electrode of the transistor 852. Will be done.

The capacitance element 862 has a function as a holding capacitance for holding the written data.

One of the source electrode and the drain electrode of the transistor 854 is electrically connected to the potential supply line VL_a. Further, the gate electrode of the transistor 854 is electrically connected to the other of the source electrode and the drain electrode of the transistor 852.

One of the anode and cathode of the light emitting element 872 is electrically connected to the potential supply line VL_b, and the other is electrically connected to the other of the source electrode and the drain electrode of the transistor 854.

As the light emitting element 872, the light emitting element shown in the first embodiment can be used.

One of the potential supply line VL_a and the potential supply line VL_b is given a high power supply potential VDD, and the other is given a low power supply potential VSS.

In the display device having the pixel circuit 801 of FIG. 22 (B), for example, the pixel circuit 801 of each line is sequentially selected by the scanning line drive circuit 804a shown in FIG. 22 (A), the transistor 852 is turned on, and the data signal is displayed. Write data.

The pixel circuit 801 to which the data is written is put into a holding state when the transistor 852 is turned off. Further, the amount of current flowing between the source electrode and the drain electrode of the transistor 854 is controlled according to the potential of the written data signal, and the light emitting element 872 emits light with brightness corresponding to the amount of flowing current. By doing this sequentially line by line, the image can be displayed.

Further, the pixel circuit may be provided with a function of correcting the influence of fluctuations such as the threshold voltage of the transistor. 23 (A) (B) and 24 (A) (B) show an example of a pixel circuit.

The pixel circuit shown in FIG. 23A has six transistors (transistors 303_1 to 303_6), a capacitive element 304, and a light emitting element 305. Further, wirings 301_1 to 301_5, and wirings 302_1 and 302_2 are electrically connected to the pixel circuit shown in FIG. 23A. As for the transistors 303_1 to 303_1, for example, a P-channel type transistor can be used.

The pixel circuit shown in FIG. 23 (B) has a configuration in which a transistor 303_7 is added to the pixel circuit shown in FIG. 23 (A). Further, the wiring 301_6 and the wiring 301_7 are electrically connected to the pixel circuit shown in FIG. 23 (B). Here, the wiring 301_5 and the wiring 301_6 may be electrically connected to each other. As the transistor 303_7, for example, a P-channel type transistor can be used.

The pixel circuit shown in FIG. 24A includes six transistors (transistors 308_1 to 308_6), a capacitive element 304, and a light emitting element 305. Further, the wirings 306_1 to 306_3 and the wirings 307_1 to 307_3 are electrically connected to the pixel circuit shown in FIG. 24 (A). Here, the wiring 306_1 and the wiring 306_3 may be electrically connected to each other. As for the transistors 308_1 to 308_6, for example, P-channel type transistors can be used.

The pixel circuit shown in FIG. 24B has two transistors (transistor 309_1 and transistor 309_2), two capacitive elements (capacitive element 304_1 and capacitive element 304_2), and a light emitting element 305. Further, wirings 311_1 to 311_3, wirings 312_1, and wirings 312_2 are electrically connected to the pixel circuit shown in FIG. 24B. Further, by adopting the configuration of the pixel circuit shown in FIG. 24 (B), for example, a voltage input-current drive system (also referred to as a CVCC system) can be adopted. As for the transistors 309_1 and 309_2, for example, P-channel type transistors can be used.

Further, the light emitting element of one aspect of the present invention can be applied to each of an active matrix method in which the pixels of the display device have an active element and a passive matrix method in which the pixels of the display device do not have an active element. ..

In the active matrix method, not only transistors but also various active elements (active elements, non-linear elements) can be used as active elements (active elements, non-linear elements). For example, MIM (Metal Insulator Metal), TFD (Thin Film Diode), or the like can also be used. Since these elements have few manufacturing processes, it is possible to reduce the manufacturing cost or improve the yield. Alternatively, since these elements have a small element size, the aperture ratio can be improved, and low power consumption and high brightness can be achieved.

As a method other than the active matrix method, it is also possible to use a passive matrix type that does not use an active element (active element, non-linear element). Since no active element (active element, non-linear element) is used, the number of manufacturing steps is small, so that the manufacturing cost can be reduced or the yield can be improved. Alternatively, since an active element (active element, non-linear element) is not used, the aperture ratio can be improved, and power consumption can be reduced or brightness can be increased.

The configuration shown in this embodiment can be used in combination with the configuration shown in other embodiments as appropriate.

(Embodiment 6)
In the present embodiment, a display device having a light emitting element according to one aspect of the present invention and an electronic device in which an input device is attached to the display device will be described with reference to FIGS. 25 to 29.

<Explanation about touch panel 1>
In this embodiment, the touch panel 2000 in which the display device and the input device are combined will be described as an example of the electronic device. Further, as an example of the input device, a case where the touch sensor is provided will be described.

25 (A) and 25 (B) are perspective views of the touch panel 2000. Note that, in FIGS. 25A and 25B, typical components of the touch panel 2000 are shown for clarity.

The touch panel 2000 has a display device 2501 and a touch sensor 2595 (see FIG. 25B). Further, the touch panel 2000 has a substrate 2510, a substrate 2570, and a substrate 2590. The substrate 2510, the substrate 2570, and the substrate 2590 are all flexible. However, any one or all of the substrate 2510, the substrate 2570, and the substrate 2590 may be configured to have no flexibility.

The display device 2501 has a plurality of pixels on the substrate 2510 and a plurality of wirings 2511 capable of supplying signals to the pixels. The plurality of wirings 2511 are routed to the outer peripheral portion of the substrate 2510, and a part of them constitutes the terminal 2519. Terminal 2519 is electrically connected to FPC2509 (1). Further, the plurality of wirings 2511 can supply signals from the signal line drive circuit 2503s (1) to the plurality of pixels.

The substrate 2590 has a touch sensor 2595 and a plurality of wires 2598 that are electrically connected to the touch sensor 2595. The plurality of wirings 2598 are routed around the outer peripheral portion of the substrate 2590, and a part thereof constitutes a terminal. Then, the terminal is electrically connected to the FPC2509 (2). In FIG. 25B, for the sake of clarity, the electrodes, wiring, and the like of the touch sensor 2595 provided on the back surface side (the surface side facing the substrate 2510) of the substrate 2590 are shown by solid lines.

As the touch sensor 2595, for example, a capacitance type touch sensor can be applied. Examples of the capacitance method include a surface type capacitance method and a projection type capacitance method.

The projected capacitance method includes a self-capacitance method and a mutual capacitance method mainly due to the difference in the drive method. It is preferable to use the mutual capacitance method because simultaneous multipoint detection is possible.

The touch sensor 2595 shown in FIG. 25B has a configuration in which a projection type capacitance type touch sensor is applied.

In addition, various sensors capable of detecting the proximity or contact of a detection target such as a finger can be applied to the touch sensor 2595.

The projection type capacitance type touch sensor 2595 has an electrode 2591 and an electrode 2592. The electrode 2591 is electrically connected to any one of the plurality of wires 2598, and the electrode 2592 is electrically connected to any other of the plurality of wires 2598.

As shown in FIGS. 25A and 25B, the electrode 2592 has a shape in which a plurality of quadrilaterals repeatedly arranged in one direction are connected at a corner.

The electrode 2591 is quadrilateral and is repeatedly arranged in a direction intersecting the extending direction of the electrode 2592.

The wiring 2594 is electrically connected to two electrodes 2591 that sandwich the electrode 2592. At this time, it is preferable that the area of the intersection between the electrode 2592 and the wiring 2594 is as small as possible. As a result, the area of the region where the electrodes are not provided can be reduced, and the variation in transmittance can be reduced. As a result, it is possible to reduce the variation in the brightness of the light transmitted through the touch sensor 2595.

The shapes of the electrode 2591 and the electrode 2592 are not limited to this, and various shapes can be taken. For example, a plurality of electrodes 2591 may be arranged so as not to form a gap as much as possible, and a plurality of electrodes 2592 may be provided at intervals so as to form a region that does not overlap with the electrode 2591 via an insulating layer. At this time, it is preferable to provide a dummy electrode electrically insulated from the two adjacent electrodes 2592 because the area of regions having different transmittances can be reduced.

<Explanation of display device>
Next, the details of the display device 2501 will be described with reference to FIG. 26 (A). FIG. 26 (A) corresponds to a cross-sectional view between the alternate long and short dash lines X1-X2 shown in FIG. 25 (B).

The display device 2501 has a plurality of pixels arranged in a matrix. The pixel has a display element and a pixel circuit for driving the display element.

In the following description, a case where a light emitting element that emits white light is applied to the display element will be described, but the display element is not limited to this. For example, light emitting elements having different emission colors may be applied so that the color of the emitted light is different for each adjacent pixel.

As the substrate 2510 and the substrate 2570, for example, the transmittance of water vapor is 1 × 10 ^-5 g ・ m ^-2・ day ^-1 or less, preferably 1 × 10 ^-6 g ・ m ^-2・ day ^-1 or less. A flexible material can be preferably used. Alternatively, it is preferable to use a material in which the coefficient of thermal expansion of the substrate 2510 and the coefficient of thermal expansion of the substrate 2570 are approximately equal. For example, a material having a linear expansion coefficient of 1 × 10 ^-3 / K or less, preferably 5 × 10 ^-5 / K or less, and more preferably 1 × 10 ^-5 / K or less can be preferably used.

The substrate 2510 is a laminate having an insulating layer 2510a for preventing the diffusion of impurities into the light emitting element, a flexible substrate 2510b, and an adhesive layer 2510c for bonding the insulating layer 2510a and the flexible substrate 2510b. .. Further, the substrate 2570 is a laminate having an insulating layer 2570a for preventing the diffusion of impurities into the light emitting element, a flexible substrate 2570b, and an adhesive layer 2570c for bonding the insulating layer 2570a and the flexible substrate 2570b. ..

As the adhesive layer 2510c and the adhesive layer 2570c, for example, polyester, polyolefin, polyamide (nylon, aramid, etc.), polyimide, polycarbonate or acrylic resin, polyurethane, epoxy resin can be used. Alternatively, a material containing a resin having a siloxane bond such as silicone can be used.

Further, a sealing layer 2560 is provided between the substrate 2510 and the substrate 2570. The sealing layer 2560 preferably has a refractive index greater than that of air. Further, as shown in FIG. 26A, when light is taken out to the sealing layer 2560 side, the sealing layer 2560 can also serve as an optical bonding layer.

Further, a sealing material may be formed on the outer peripheral portion of the sealing layer 2560. By using the sealing material, the light emitting element 2550R can be provided in the area surrounded by the substrate 2510, the substrate 2570, the sealing layer 2560, and the sealing material. The sealing layer 2560 may be filled with an inert gas (nitrogen, argon, etc.). Further, a desiccant may be provided in the inert gas to adsorb moisture or the like. Further, as the above-mentioned sealing material, for example, an epoxy resin or a glass frit is preferably used. Further, as the material used for the sealing material, it is preferable to use a material that does not allow moisture or oxygen to permeate.

Further, the display device 2501 has pixels 2502R. Further, the pixel 2502R has a light emitting module 2580R.

The pixel 2502R has a light emitting element 2550R and a transistor 2502t capable of supplying electric power to the light emitting element 2550R. The transistor 2502t functions as a part of the pixel circuit. Further, the light emitting module 2580R has a light emitting element 2550R and a colored layer 2567R.

The light emitting element 2550R has a lower electrode, an upper electrode, and an EL layer between the lower electrode and the upper electrode. As the light emitting element 2550R, for example, the light emitting element shown in the first to third embodiments can be applied.

Further, a microcavity structure may be adopted between the lower electrode and the upper electrode to increase the light intensity at a specific wavelength.

When the sealing layer 2560 is provided on the side from which light is taken out, the sealing layer 2560 is in contact with the light emitting element 2550R and the colored layer 2567R.

The colored layer 2567R is located at a position where it overlaps with the light emitting element 2550R. As a result, a part of the light emitted by the light emitting element 2550R passes through the colored layer 2567R and is emitted to the outside of the light emitting module 2580R in the direction of the arrow shown in the drawing.

Further, the display device 2501 is provided with a light-shielding layer 2567BM in the direction of emitting light. The light-shielding layer 2567BM is provided so as to surround the colored layer 2567R.

The colored layer 2567R may have a function of transmitting light in a specific wavelength band. For example, a color filter that transmits light in the red wavelength band, a color filter that transmits light in the green wavelength band, and the like. A color filter that transmits light in the blue wavelength band, a color filter that transmits light in the yellow wavelength band, and the like can be used. Each color filter can be formed by a printing method, an inkjet method, an etching method using a photolithography technique, or the like using various materials.

Further, the display device 2501 is provided with an insulating layer 2521. The insulating layer 2521 covers the transistor 2502t. The insulating layer 2521 has a function for flattening unevenness caused by the pixel circuit. Further, the insulating layer 2521 may be provided with a function capable of suppressing the diffusion of impurities. As a result, it is possible to suppress a decrease in reliability of the transistor 2502t or the like due to diffusion of impurities.

Further, the light emitting element 2550R is formed above the insulating layer 2521. Further, the lower electrode of the light emitting element 2550R is provided with a partition wall 2528 that overlaps the end of the lower electrode. A spacer for controlling the distance between the substrate 2510 and the substrate 2570 may be formed on the partition wall 2528.

The scanning line drive circuit 2503g (1) has a transistor 2503t and a capacitance element 2503c. The drive circuit can be formed on the same substrate in the same process as the pixel circuit.

Further, wiring 2511 capable of supplying a signal is provided on the substrate 2510. Further, a terminal 2519 is provided on the wiring 2511. Further, the FPC2509 (1) is electrically connected to the terminal 2519. Further, the FPC2509 (1) has a function of supplying a video signal, a clock signal, a start signal, a reset signal, and the like. A printed wiring board (PWB) may be attached to the FPC2509 (1).

Further, transistors having various structures can be applied to the display device 2501. In FIG. 26 (A), a case where a bottom gate type transistor is applied is illustrated, but the present invention is not limited to this, and for example, the top gate type transistor shown in FIG. 26 (B) is displayed on the display device 2501. It may be configured to be applied to.

The polarities of the transistor 2502t and the transistor 2503t are not particularly limited, and a structure having N-channel type and P-channel type transistors, and a structure consisting of only one of N-channel type transistor and P-channel type transistor may be used. You may use it. Further, the crystallinity of the semiconductor film used for the transistors 2502t and 2503t is not particularly limited. For example, an amorphous semiconductor film or a crystalline semiconductor film can be used. Further, as the semiconductor material, a group 14 semiconductor (for example, a semiconductor having silicon), a compound semiconductor (including an oxide semiconductor), an organic semiconductor, or the like can be used. The off-current of the transistor can be reduced by using an oxide semiconductor having an energy gap of 2 eV or more, preferably 2.5 eV or more, more preferably 3 eV or more for either one or both of the transistor 2502t and the transistor 2503t. Therefore, it is preferable. Examples of the oxide semiconductor include In-Ga oxide, In-M-Zn oxide (M represents Al, Ga, Y, Zr, La, Ce, Sn, Hf, or Nd).

<Explanation of touch sensor>
Next, the details of the touch sensor 2595 will be described with reference to FIG. 26 (C). FIG. 26 (C) corresponds to a cross-sectional view between the alternate long and short dash lines X3-X4 shown in FIG. 25 (B).

The touch sensor 2595 has electrodes 2591 and 2592 arranged in a staggered manner on the substrate 2590, an insulating layer 2593 covering the electrodes 2591 and 2592, and wiring 2594 for electrically connecting adjacent electrodes 2591.

The electrode 2591 and the electrode 2592 are formed by using a conductive material having translucency. As the conductive material having translucency, a conductive oxide such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, and zinc oxide added with gallium can be used. A membrane containing graphene can also be used. The graphene-containing film can be formed by reducing, for example, a film-like film containing graphene oxide. Examples of the method of reduction include a method of applying heat.

For example, a conductive material having translucency is formed on a substrate 2590 by a sputtering method, and then unnecessary parts are removed by various pattern forming techniques such as a photolithography method to form electrodes 2591 and 2592. can do.

As the material used for the insulating layer 2593, for example, a resin such as an acrylic resin or an epoxy resin, a resin having a siloxane bond such as silicone, or an inorganic insulating material such as silicon oxide, silicon oxide nitride, or aluminum oxide is used. You can also.

Further, an opening reaching the electrode 2591 is provided in the insulating layer 2593, and the wiring 2594 is electrically connected to the adjacent electrode 2591. Since the translucent conductive material can increase the aperture ratio of the touch panel, it can be suitably used for wiring 2594. Further, a material having a higher conductivity than the electrode 2591 and the electrode 2592 can be suitably used for the wiring 2594 because the electric resistance can be reduced.

The electrode 2592 extends in one direction, and a plurality of electrodes 2592 are provided in a stripe shape. Further, the wiring 2594 is provided so as to intersect with the electrode 2592.

A pair of electrodes 2591 are provided with one electrode 2592 interposed therebetween. Further, the wiring 2594 electrically connects the pair of electrodes 2591.

The plurality of electrodes 2591 do not necessarily have to be arranged in a direction orthogonal to one electrode 2592, and may be arranged so as to form an angle larger than 0 degrees and less than 90 degrees.

Further, the wiring 2598 is electrically connected to the electrode 2591 or the electrode 2592. Further, a part of the wiring 2598 functions as a terminal. As the wiring 2598, for example, a metal material such as aluminum, gold, platinum, silver, nickel, titanium, tungsten, chromium, molybdenum, iron, cobalt, copper, or palladium, or an alloy material containing the metal material can be used. it can.

The touch sensor 2595 may be protected by providing an insulating layer that covers the insulating layer 2593 and the wiring 2594.

Further, the connection layer 2599 electrically connects the wiring 2598 and the FPC2509 (2).

As the connecting layer 2599, an anisotropic conductive film (ACF: Anisotropic Conducive Film), an anisotropic conductive paste (ACP: Anisotropic Conducive Paste), or the like can be used.

<Explanation about touch panel 2>
Next, the details of the touch panel 2000 will be described with reference to FIG. 27 (A). FIG. 27 (A) corresponds to a cross-sectional view between the alternate long and short dash lines X5-X6 shown in FIG. 25 (A).

The touch panel 2000 shown in FIG. 27 (A) has a configuration in which the display device 2501 described in FIG. 26 (A) and the touch sensor 2595 described in FIG. 26 (C) are bonded together.

Further, the touch panel 2000 shown in FIG. 27 (A) has an adhesive layer 2597 and an antireflection layer 2567p in addition to the configurations described in FIGS. 26 (A) and 26 (C).

The adhesive layer 2597 is provided in contact with the wiring 2594. The adhesive layer 2597 has a substrate 2590 attached to the substrate 2570 so that the touch sensor 2595 overlaps the display device 2501. Further, the adhesive layer 2597 is preferably translucent. Further, as the adhesive layer 2597, a thermosetting resin or an ultraviolet curable resin can be used. For example, an acrylic resin, a urethane resin, an epoxy resin, or a siloxane resin can be used.

The antireflection layer 2567p is provided at a position overlapping the pixels. As the antireflection layer 2567p, for example, a circularly polarizing plate can be used.

Next, a touch panel having a configuration different from that shown in FIG. 27 (A) will be described with reference to FIG. 27 (B).

FIG. 27B is a cross-sectional view of the touch panel 2001. The touch panel 2001 shown in FIG. 27 (B) is different from the touch panel 2000 shown in FIG. 27 (A) in the position of the touch sensor 2595 with respect to the display device 2501. Here, the different configurations will be described in detail, and the description of the touch panel 2000 will be used for the parts where the same configurations can be used.

The colored layer 2567R is located at a position where it overlaps with the light emitting element 2550R. Further, the light emitting element 2550R shown in FIG. 27B emits light to the side where the transistor 2502t is provided. As a result, a part of the light emitted by the light emitting element 2550R passes through the colored layer 2567R and is emitted to the outside of the light emitting module 2580R in the direction of the arrow shown in the drawing.

Further, the touch sensor 2595 is provided on the substrate 2510 side of the display device 2501.

The adhesive layer 2597 is located between the substrate 2510 and the substrate 2590, and attaches the display device 2501 and the touch sensor 2595.

As shown in FIGS. 27A and 27B, the light emitted from the light emitting element may be emitted through either or both of the substrate 2510 side and the substrate 2570 side.

<Explanation of how to drive the touch panel>
Next, an example of the touch panel driving method will be described with reference to FIGS. 28A and 28B.

FIG. 28 (A) is a block diagram showing a configuration of a mutual capacitance type touch sensor. FIG. 28A shows a pulse voltage output circuit 2601 and a current detection circuit 2602. In FIG. 28A, the electrode 2621 to which the pulse voltage is applied is designated as X1-X6, and the electrode 2622 that detects the change in current is designated as Y1-Y6. Further, FIG. 28A shows a capacitance 2603 formed by overlapping the electrode 2621 and the electrode 2622. The functions of the electrode 2621 and the electrode 2622 may be interchanged with each other.

The pulse voltage output circuit 2601 is a circuit for sequentially applying pulses to the wirings of X1-X6. By applying a pulse voltage to the wiring of X1-X6, an electric field is generated between the electrode 2621 and the electrode 2622 forming the capacitance 2603. The proximity or contact of the object to be detected can be detected by utilizing the fact that the electric field generated between the electrodes causes a change in the mutual capacitance of the capacitance 2603 due to shielding or the like.

The current detection circuit 2602 is a circuit for detecting a change in the current in the wiring of Y1-Y6 due to a change in the mutual capacitance in the capacitance 2603. In the wiring of Y1-Y6, there is no change in the current value detected when there is no proximity or contact of the detected object, but the current value when the mutual capacitance decreases due to the proximity or contact of the detected object to be detected. Detects a decreasing change. The current may be detected by using an integrator circuit or the like.

Next, FIG. 28 (B) shows a timing chart of input / output waveforms in the mutual capacitance type touch sensor shown in FIG. 28 (A). In FIG. 28B, it is assumed that the detected object is detected in each matrix in one frame period. Further, FIG. 28B shows two cases, a case where the detected object is not detected (non-touch) and a case where the detected object is detected (touch). The wiring of Y1-Y6 shows a waveform with a voltage value corresponding to the detected current value.

A pulse voltage is sequentially applied to the wirings of X1-X6, and the waveform in the wirings of Y1-Y6 changes according to the pulse voltage. When there is no proximity or contact of the object to be detected, the waveform of Y1-Y6 changes uniformly according to the change of the voltage of the wiring of X1-X6. On the other hand, since the current value decreases at the location where the object to be detected is close to or in contact with the object to be detected, the corresponding voltage value waveform also changes.

By detecting the change in mutual capacitance in this way, the proximity or contact of the object to be detected can be detected.

<Explanation of sensor circuit>
Further, although FIG. 28 (A) shows the configuration of a passive matrix type touch sensor in which only the capacitance 2603 is provided at the intersection of the wirings as the touch sensor, an active matrix type touch sensor having a transistor and a capacitance may be used. FIG. 29 shows an example of the sensor circuit included in the active matrix type touch sensor.

The sensor circuit shown in FIG. 29 has a capacitance of 2603, a transistor 2611, a transistor 2612, and a transistor 2613.

Transistor 2613 is given a signal G2 to the gate, a voltage VRES to one of the source or drain, and the other is electrically connected to one electrode of capacitance 2603 and the gate of transistor 2611. In transistor 2611, one of the source and drain is electrically connected to one of the source and drain of transistor 2612, and voltage VSS is applied to the other. Transistor 2612 receives a signal G1 at the gate and the other of the source or drain is electrically connected to the wiring ML. A voltage VSS is applied to the other electrode of capacitance 2603.

Next, the operation of the sensor circuit shown in FIG. 29 will be described. First, a potential for turning on the transistor 2613 is given as the signal G2, so that a potential corresponding to the voltage VRES is given to the node n to which the gate of the transistor 2611 is connected. Next, the potential of the node n is maintained by giving the potential to turn off the transistor 2613 as the signal G2.

Subsequently, the potential of the node n changes from VRES as the mutual capacitance of the capacitance 2603 changes due to the proximity or contact of the object to be detected such as a finger.

The read operation gives the signal G1 a potential to turn on the transistor 2612. The current flowing through the transistor 2611, that is, the current flowing through the wiring ML, changes according to the potential of the node n. By detecting this current, the proximity or contact of the object to be detected can be detected.

As the transistor 2611, the transistor 2612, and the transistor 2613, it is preferable to use an oxide semiconductor layer for the semiconductor layer in which the channel region is formed. In particular, by applying such a transistor to the transistor 2613, the potential of the node n can be maintained for a long period of time, and the frequency of the operation (refresh operation) of resupplying the VRES to the node n can be reduced. it can.

The configuration shown in this embodiment can be used in combination with the configuration shown in other embodiments as appropriate.

(Embodiment 7)
In the present embodiment, the display module and the electronic device having the light emitting element of one aspect of the present invention will be described with reference to FIGS. 30 and 31.

<Explanation of display module>
The display module 8000 shown in FIG. 30 has a touch sensor 8004 connected to the FPC 8003, a display device 8006 connected to the FPC 8005, a frame 8009, a printed circuit board 8010, and a battery 8011 between the upper cover 8001 and the lower cover 8002. ..

The light emitting element of one aspect of the present invention can be used, for example, in the display device 8006.

The shape and dimensions of the upper cover 8001 and the lower cover 8002 can be appropriately changed according to the sizes of the touch sensor 8004 and the display device 8006.

The touch sensor 8004 can be used by superimposing a resistive film type or capacitance type touch sensor on the display device 8006. It is also possible to provide the opposite substrate (sealing substrate) of the display device 8006 with a touch sensor function. Further, it is also possible to provide an optical sensor in each pixel of the display device 8006 to form an optical touch sensor.

In addition to the protective function of the display device 8006, the frame 8009 has a function as an electromagnetic shield for blocking electromagnetic waves generated by the operation of the printed circuit board 8010. Further, the frame 8009 may have a function as a heat radiating plate.

The printed circuit board 8010 has a power supply circuit, a signal processing circuit for outputting a video signal and a clock signal. The power source for supplying electric power to the power supply circuit may be an external commercial power source or a separately provided battery 8011. The battery 8011 can be omitted when a commercial power source is used.

Further, the display module 8000 may be additionally provided with members such as a polarizing plate, a retardation plate, and a prism sheet.

<Explanation of electronic devices>
31 (A) to 31 (G) are diagrams showing electronic devices. These electronic devices include a housing 9000, a display unit 9001, a speaker 9003, an operation key 9005 (including a power switch or an operation switch), a connection terminal 9006, and a sensor 9007 (force, displacement, position, speed, acceleration, angular velocity, etc.). Includes the ability to measure speed, distance, light, liquid, magnetism, temperature, chemicals, voice, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor or infrared. ), Microphone 9008, and the like.

The electronic devices shown in FIGS. 31 (A) to 31 (G) can have various functions. For example, a function to display various information (still images, moving images, text images, etc.) on the display unit, a touch sensor function, a function to display a calendar, date or time, etc., a function to control processing by various software (programs). , Wireless communication function, function to connect to various computer networks using wireless communication function, function to transmit or receive various data using wireless communication function, read program or data recorded on recording medium It can have a function of displaying on a display unit, and the like. The functions that the electronic devices shown in FIGS. 31 (A) to 31 (G) can have are not limited to these, and can have various functions. Further, although not shown in FIGS. 31 (A) to 31 (G), the electronic device may have a configuration having a plurality of display units. In addition, the electronic device is provided with a camera or the like, and has a function of shooting a still image, a function of shooting a moving image, a function of saving the shot image in a recording medium (external or built in the camera), and displaying the shot image on a display unit. It may have a function to perform.

Details of the electronic devices shown in FIGS. 31 (A) to 31 (G) will be described below.

FIG. 31 (A) is a perspective view showing a mobile information terminal 9100. The display unit 9001 included in the personal digital assistant 9100 has flexibility. Therefore, it is possible to incorporate the display unit 9001 along the curved surface of the curved housing 9000. Further, the display unit 9001 is provided with a touch sensor and can be operated by touching the screen with a finger or a stylus. For example, the application can be started by touching the icon displayed on the display unit 9001.

FIG. 31 (B) is a perspective view showing a mobile information terminal 9101. The mobile information terminal 9101 has one or more functions selected from, for example, a telephone, a notebook, an information browsing device, and the like. Specifically, it can be used as a smartphone. Although the speaker 9003, the connection terminal 9006, the sensor 9007, and the like are omitted from the figure, the mobile information terminal 9101 can be provided at the same position as the mobile information terminal 9100 shown in FIG. 31 (A). Further, the mobile information terminal 9101 can display character and image information on a plurality of surfaces thereof. For example, three operation buttons 9050 (also referred to as operation icons or simply icons) can be displayed on one surface of the display unit 9001. Further, the information 9051 indicated by the broken line rectangle can be displayed on another surface of the display unit 9001. As an example of information 9051, a display notifying an incoming call of e-mail, SNS (social networking service), telephone, etc., a title of e-mail, SNS, etc., a sender name of e-mail, SNS, etc., date and time, time. , Battery level, antenna reception strength, etc. Alternatively, the operation button 9050 or the like may be displayed instead of the information 9051 at the position where the information 9051 is displayed.

FIG. 31 (C) is a perspective view showing a mobile information terminal 9102. The mobile information terminal 9102 has a function of displaying information on three or more surfaces of the display unit 9001. Here, an example is shown in which information 9052, information 9053, and information 9054 are displayed on different surfaces. For example, the user of the mobile information terminal 9102 can check the display (here, information 9053) with the mobile information terminal 9102 stored in the chest pocket of the clothes. Specifically, the telephone number or name of the caller of the incoming call is displayed at a position that can be observed from above the mobile information terminal 9102. The user can check the display and determine whether or not to receive the call without taking out the mobile information terminal 9102 from the pocket.

FIG. 31 (D) is a perspective view showing a wristwatch-type portable information terminal 9200. The personal digital assistant 9200 can execute various applications such as mobile phone, e-mail, text viewing and creation, music playback, Internet communication, and computer games. Further, the display unit 9001 is provided with a curved display surface, and can display along the curved display surface. In addition, the personal digital assistant 9200 can execute short-range wireless communication standardized for communication. For example, by communicating with a headset capable of wireless communication, it is possible to make a hands-free call. Further, the mobile information terminal 9200 has a connection terminal 9006, and can directly exchange data with another information terminal via a connector. It is also possible to charge via the connection terminal 9006. The charging operation may be performed by wireless power supply without going through the connection terminal 9006.

31 (E), (F), and (G) are perspective views showing a foldable mobile information terminal 9201. Further, FIG. 31 (E) is a perspective view of a state in which the mobile information terminal 9201 is deployed, and FIG. 31 (F) is a state in which the mobile information terminal 9201 is in the process of changing from one of the expanded state or the folded state to the other. 31 (G) is a perspective view of the mobile information terminal 9201 in a folded state. The mobile information terminal 9201 is excellent in portability in the folded state, and is excellent in display listability due to a wide seamless display area in the unfolded state. The display unit 9001 included in the personal digital assistant terminal 9201 is supported by three housings 9000 connected by a hinge 9055. By bending between the two housings 9000 via the hinge 9055, the portable information terminal 9201 can be reversibly deformed from the unfolded state to the folded state. For example, the portable information terminal 9201 can be bent with a radius of curvature of 1 mm or more and 150 mm or less.

The electronic device described in the present embodiment is characterized by having a display unit for displaying some information. However, the light emitting element of one aspect of the present invention can also be applied to an electronic device having no display unit. Further, in the display unit of the electronic device described in the present embodiment, a configuration having flexibility and being able to display along a curved display surface or a configuration of a foldable display unit has been exemplified. However, the present invention is not limited to this, and the configuration may be such that the display is performed on a flat surface portion without having flexibility.

The configuration shown in this embodiment can be used in combination with the configuration shown in other embodiments as appropriate.

(Embodiment 8)
In the present embodiment, the light emitting device having the light emitting element of one aspect of the present invention will be described with reference to FIGS. 32 and 33.

A perspective view of the light emitting device 3000 shown in the present embodiment is shown in FIG. 32 (A), and a cross-sectional view corresponding to the alternate long and short dash line EF shown in FIG. 32 (A) is shown in FIG. 32 (B). In FIG. 32 (A), some of the components are indicated by broken lines in order to avoid complication of the drawing.

The light emitting device 3000 shown in FIGS. 32 (A) and 32 (B) has a substrate 3001, a light emitting element 3005 on the substrate 3001, a first sealing region 3007 provided on the outer periphery of the light emitting element 3005, and a first sealing. It has a second sealing region 3009 provided on the outer periphery of the stop region 3007.

Further, the light emitted from the light emitting element 3005 is emitted from either or both of the substrate 3001 and the substrate 3003. In FIGS. 32 (A) and 32 (B), the configuration in which the light emitted from the light emitting element 3005 is emitted to the lower side (the substrate 3001 side) will be described.

Further, as shown in FIGS. 32 (A) and 32 (B), in the light emitting device 3000, the light emitting element 3005 is arranged so as to be surrounded by the first sealing region 3007 and the second sealing region 3009. It has a heavy sealing structure. With the double-sealed structure, external impurities (for example, water, oxygen, etc.) that enter the light emitting element 3005 side can be suitably suppressed. However, it is not always necessary to provide the first sealing region 3007 and the second sealing region 3009. For example, it may be configured only in the first sealing region 3007.

In FIG. 32B, the first sealing region 3007 and the second sealing region 3009 are provided in contact with the substrate 3001 and the substrate 3003. However, the present invention is not limited to this, and for example, one or both of the first sealing region 3007 and the second sealing region 3009 is provided in contact with the insulating film or conductive film formed above the substrate 3001. It may be configured. Alternatively, one or both of the first sealing region 3007 and the second sealing region 3009 may be provided in contact with the insulating film or the conductive film formed below the substrate 3003.

The substrate 3001 and the substrate 3003 may have the same configurations as the substrate 200 and the substrate 220 described in the third embodiment, respectively. The light emitting element 3005 may have the same configuration as the light emitting element described in the previous embodiment.

As the first sealing region 3007, a material containing glass (for example, glass frit, glass ribbon, etc.) may be used. Further, as the second sealing region 3009, a material containing a resin may be used. By using a material containing glass as the first sealing region 3007, productivity and sealing property can be improved. Further, by using a material containing a resin as the second sealing region 3009, impact resistance and heat resistance can be improved. However, the first sealing region 3007 and the second sealing region 3009 are not limited to this, and the first sealing region 3007 is formed of a material containing a resin, and the second sealing region 3009 May be made of a material containing glass.

Examples of the above-mentioned glass frit include magnesium oxide, calcium oxide, strontium oxide, barium oxide, cesium oxide, sodium oxide, potassium oxide, boron oxide, vanadium oxide, zinc oxide, tellurium oxide, aluminum oxide, silicon dioxide, and the like. Lead oxide, tin oxide, phosphorus oxide, ruthenium oxide, rhodium oxide, iron oxide, copper oxide, manganese dioxide, molybdenum oxide, niobium oxide, titanium oxide, tungsten oxide, bismuth oxide, zirconium oxide, lithium oxide, antimony oxide, boric acid Includes lead glass, tin phosphate glass, vanadate glass, borosilicate glass and the like. In order to absorb infrared light, it is preferable to contain at least one kind of transition metal.

Further, as the above-mentioned glass frit, for example, a frit paste is applied on a substrate, and heat treatment or laser irradiation is performed on the frit paste. The frit paste contains the above glass frit and a resin (also referred to as a binder) diluted with an organic solvent. Further, a glass frit to which an absorbent for absorbing light having a wavelength of laser light is added may be used. Further, as the laser, for example, it is preferable to use an Nd: YAG laser, a semiconductor laser, or the like. Further, the laser irradiation shape at the time of laser irradiation may be circular or quadrangular.

Further, as the material containing the above-mentioned resin, for example, polyester, polyolefin, polyamide (nylon, aramid, etc.), polyimide, polycarbonate or acrylic resin, polyurethane, epoxy resin can be used. Alternatively, a material containing a resin having a siloxane bond such as silicone can be used.

When a material containing glass is used for either or both of the first sealing region 3007 and the second sealing region 3009, the coefficient of thermal expansion of the material containing the glass and the substrate 3001 is close to each other. preferable. With the above configuration, it is possible to prevent cracks in the material containing glass or the substrate 3001 due to thermal stress.

For example, when a material containing glass is used for the first sealing region 3007 and a material containing resin is used for the second sealing region 3009, the following excellent effects are obtained.

The second sealing region 3009 is provided on the side closer to the outer peripheral portion of the light emitting device 3000 than the first sealing region 3007. The light emitting device 3000 becomes more distorted due to an external force or the like toward the outer peripheral portion. Therefore, the outer peripheral side of the light emitting device 3000 in which the strain becomes large, that is, the second sealing region 3009 is sealed with a material containing a resin, and the first sealing provided inside the second sealing region 3009. By sealing the stop region 3007 with a material containing glass, the light emitting device 3000 is less likely to break even if distortion such as an external force occurs.

Further, as shown in FIG. 32 (B), a first region 3011 is formed in a region surrounded by the substrate 3001, the substrate 3003, the first sealing region 3007, and the second sealing region 3009. To. A second region 3013 is formed in a region surrounded by the substrate 3001, the substrate 3003, the light emitting element 3005, and the first sealing region 3007.

The first region 3011 and the second region 3013 are preferably filled with an inert gas such as a rare gas or a nitrogen gas. The first region 3011 and the second region 3013 are preferably in a decompressed state rather than in an atmospheric pressure state.

Further, a modified example of the configuration shown in FIG. 32 (B) is shown in FIG. 32 (C). FIG. 32C is a cross-sectional view showing a modified example of the light emitting device 3000.

FIG. 32C shows a configuration in which a recess is provided in a part of the substrate 3003 and a desiccant 3018 is provided in the recess. Other configurations are the same as those shown in FIG. 32 (B).

As the desiccant 3018, a substance that adsorbs water or the like by chemical adsorption or a substance that adsorbs water or the like by physical adsorption can be used. For example, substances that can be used as the desiccant 3018 include alkali metal oxides, alkaline earth metal oxides (calcium oxide, barium oxide, etc.), sulfates, metal halides, perchlorates, zeolites, and the like. Examples include silica gel.

Next, a modified example of the light emitting device 3000 shown in FIG. 32 (B) will be described with reference to FIGS. 33 (A), (B), (C), and (D). 33 (A), (B), (C), and (D) are cross-sectional views illustrating a modified example of the light emitting device 3000 shown in FIG. 32 (B).

The light emitting device shown in FIGS. 33 (A), (B), (C), and (D) has a configuration in which the first sealing region 3007 is provided without providing the second sealing region 3009. Further, the light emitting device shown in FIGS. 33 (A), (B), (C) and (D) has a region 3014 instead of the second region 3013 shown in FIG. 32 (B).

As the region 3014, for example, polyester, polyolefin, polyamide (nylon, aramid, etc.), polyimide, polycarbonate or acrylic resin, polyurethane, epoxy resin can be used. Alternatively, a material containing a resin having a siloxane bond such as silicone can be used.

By using the above-mentioned material as the region 3014, a so-called solid-sealed light emitting device can be obtained.

Further, the light emitting device shown in FIG. 33 (B) has a configuration in which a substrate 3015 is provided on the substrate 3001 side of the light emitting device shown in FIG. 33 (A).

The substrate 3015 has irregularities as shown in FIG. 33 (B). By providing the uneven substrate 3015 on the side from which the light of the light emitting element 3005 is taken out, the efficiency of taking out the light from the light emitting element 3005 can be improved. In addition, instead of the structure having unevenness as shown in FIG. 33B, a substrate functioning as a diffusion plate may be provided.

Further, the light emitting device shown in FIG. 33 (C) has a structure in which light is extracted from the substrate 3003 side, whereas the light emitting device shown in FIG. 33 (A) has a structure in which light is extracted from the substrate 3001 side.

The light emitting device shown in FIG. 33C has a substrate 3015 on the substrate 3003 side. Other configurations are the same as those of the light emitting device shown in FIG. 33 (B).

Further, the light emitting device shown in FIG. 33 (D) has a configuration in which a substrate 3016 is provided without providing the substrates 3003 and 3015 of the light emitting device shown in FIG. 33 (C).

The substrate 3016 has a first unevenness located on the near side of the light emitting element 3005 and a second unevenness located on the far side of the light emitting element 3005. With the configuration shown in FIG. 33 (D), the efficiency of extracting light from the light emitting element 3005 can be further improved.

Therefore, by implementing the configuration shown in the present embodiment, it is possible to realize a light emitting device in which deterioration of the light emitting element due to impurities such as moisture and oxygen is suppressed. Alternatively, by implementing the configuration shown in the present embodiment, a light emitting device having high light extraction efficiency can be realized.

The configuration shown in this embodiment can be appropriately combined with the configurations shown in other embodiments.

(Embodiment 9)
In the present embodiment, an example of applying the light emitting element of one aspect of the present invention to various lighting devices and electronic devices will be described with reference to FIGS. 34 and 35.

By manufacturing the light emitting element of one aspect of the present invention on a flexible substrate, it is possible to realize an electronic device and a lighting device having a light emitting region having a curved surface.

Further, the light emitting device to which one aspect of the present invention is applied can also be applied to lighting of an automobile, and for example, lighting can be installed on a dashboard, a windshield, a ceiling, or the like.

FIG. 34 (A) shows a perspective view of one side of the multifunction terminal 3500, and FIG. 34 (B) shows a perspective view of the other side of the multifunction terminal 3500. In the multifunction terminal 3500, a display unit 3504, a camera 3506, a lighting 3508, and the like are incorporated in a housing 3502. The light emitting device of one aspect of the present invention can be used for the illumination 3508.

The illumination 3508 functions as a surface light source by using the light emitting device of one aspect of the present invention. Therefore, unlike a point light source typified by an LED, light emission with less directivity can be obtained. For example, when the illumination 3508 and the camera 3506 are used in combination, the illumination 3508 can be turned on or blinked to be imaged by the camera 3506. Since the illumination 3508 has a function as a surface light source, it is possible to take a picture as if it was taken under natural light.

The multifunctional terminal 3500 shown in FIGS. 34 (A) and 34 (B) can have various functions like the electronic devices shown in FIGS. 31 (A) to 31 (G).

In addition, inside the housing 3502, a speaker, a sensor (force, displacement, position, speed, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, voice, time, hardness, electric field, current , Includes the ability to measure voltage, power, radiation, flow rate, humidity, gradient, vibration, odor or infrared rays), microphones and the like. Further, by providing a detection device having a sensor for detecting the inclination of a gyro, an acceleration sensor, etc. inside the multifunction terminal 3500, the orientation (vertical or horizontal) of the multifunction terminal 3500 can be determined and the display unit 3504 can be determined. It is possible to automatically switch the screen display of.

The display unit 3504 can also function as an image sensor. For example, the person can be authenticated by touching the display unit 3504 with a palm or a finger and imaging a palm print, a fingerprint, or the like. Further, if the display unit 3504 uses a backlight that emits near-infrared light or a sensing light source that emits near-infrared light, it is possible to image finger veins, palmar veins, and the like. The light emitting device of one aspect of the present invention may be applied to the display unit 3054.

FIG. 34 (C) shows a perspective view of the security light 3600. The light 3600 has a lighting 3608 on the outside of the housing 3602, and the speaker 3610 and the like are incorporated in the housing 3602. The light emitting device of one aspect of the present invention can be used for illumination 3608.

The light 3600 can emit light by, for example, holding, holding, or holding the illumination 3608. Further, an electronic circuit capable of controlling the light emitting method from the light 3600 may be provided inside the housing 3602. The electronic circuit may be, for example, a circuit capable of emitting light once or intermittently a plurality of times, or a circuit capable of adjusting the amount of light emitted by controlling the current value of the emission. Good. Further, a circuit may be incorporated so that a loud alarm sound is output from the speaker 3610 at the same time as the light emission of the illumination 3608.

Since the light 3600 can emit light in all directions, it can be threatened with light or light and sound toward, for example, a thug. Further, the light 3600 may be provided with a camera such as a digital still camera and a function having a shooting function.

FIG. 35 shows an example in which the light emitting element is used as an indoor lighting device 8501. Since the light emitting element can have a large area, it is possible to form a large area lighting device. In addition, by using a housing having a curved surface, it is possible to form a lighting device 8502 having a curved light emitting region. The light emitting element shown in this embodiment has a thin film shape, and has a high degree of freedom in the design of the housing. Therefore, it is possible to form a lighting device with various elaborate designs. Further, a large lighting device 8503 may be provided on the wall surface of the room. Further, the lighting devices 8501, 8502, 8503 may be provided with a touch sensor to turn the power on or off.

Further, by using the light emitting element on the surface side of the table, the lighting device 8504 having a function as a table can be obtained. By using a light emitting element as a part of other furniture, it is possible to obtain a lighting device having a function as furniture.

As described above, the lighting device and the electronic device can be obtained by applying the light emitting device of one aspect of the present invention. The applicable lighting devices and electronic devices are not limited to those shown in the present embodiment, and can be applied to electronic devices in all fields.

Moreover, the configuration shown in this embodiment can be used in combination with the configuration shown in other embodiments as appropriate.

In this embodiment, a production example of a light emitting element (light emitting element 1 to light emitting element 3) and a comparative light emitting element (comparative light emitting element 1 and comparative light emitting element 2), which is one aspect of the present invention, is shown. The schematic cross-sectional view of the light emitting element produced in this embodiment is the same as the light emitting element shown in FIG. 1 (A). The details of the element structure are shown in Table 2. The structures and abbreviations of the compounds used in this example are shown below. As the host material for the light emitting layer, the compound shown in the first embodiment was used.

<Manufacturing of light emitting element 1>
An ITSO film was formed on the substrate as the electrode 101 so as to have a thickness of 110 nm. The electrode area of the electrode 101 was 4 mm ² (2 mm × 2 mm).

Next, the EL layer 100 was formed on the electrode 101. As the hole injection layer 111, PCPPn and molybdenum oxide (MoO ₃ ) were co-deposited so that the weight ratio (PCPPn: MoO ₃ ) was 1: 0.5 and the thickness was 50 nm. Further, as the hole transport layer 112, PCPPn was deposited so as to have a thickness of 30 nm.

Next, as the light emitting layer 130, CzPA and 1,6 mM FLPAPrn were co-deposited so that the weight ratio (CzPA: 1,6 mM FLPAPrn) was 1: 0.04 and the thickness was 25 nm. In the light emitting layer 130, CzPA is a host material and 1,6 mM FLPAPrn is a fluorescent material (guest material).

Further, BPhen was deposited on the light emitting layer 130 as an electron transport layer 118 so as to have a thickness of 25 nm. Next, lithium fluoride (LiF) was deposited as an electron injection layer 119 so as to have a thickness of 1 nm.

Further, as the electrode 102, aluminum (Al) was formed so as to have a thickness of 200 nm.

Next, the light emitting element 1 was sealed by fixing the sealing substrate to the substrate on which the EL layer 100 was formed using the organic EL sealing material in the glove box having a nitrogen atmosphere. Specifically, a sealing material is applied around the EL layer 100 formed on the substrate, the substrate and the sealing substrate are bonded together, and ultraviolet light having a wavelength of 365 nm is irradiated at 6 J / cm ² to achieve 80. Heat-treated at ° C. for 1 hour. The light emitting element 1 was obtained by the above steps.

<Manufacturing of light emitting element 2>
The light emitting element 2 differs from the above-mentioned manufacturing of the light emitting element 1 only in the steps of forming the hole injection layer 111 and the light emitting layer 130, and the other steps are the same manufacturing methods as those of the light emitting element 1.

As the hole injection layer 111 of the light emitting element 2, PCPPn and MoO ₃ were co-deposited so that the weight ratio (PCPPn: MoO ₃ ) was 1: 0.5 and the thickness was 60 nm.

Further, as the light emitting layer 130 of the light emitting element 2, t-BuDNA and 1,6 mM FLPAPrn are arranged so that the weight ratio (t-BuDNA: 1,6 mM FLPAPrn) is 1: 0.03 and the thickness is 25 nm. Co-deposited. In the light emitting layer 130, t-BuDNA is a host material and 1.6 mM FLPAPrn is a fluorescent material (guest material).

<Manufacturing of light emitting element 3, comparative light emitting element 1, and comparative light emitting element 2>
The light emitting element 3, the comparative light emitting element 1, and the comparative light emitting element 2 differ only from the manufacturing of the light emitting element 2 shown above and the step of forming the light emitting layer 130, and the other steps are the same manufacturing method as that of the light emitting element 2. did.

As the light emitting layer 130 of the light emitting element 3, cgDBCzPA and 1,6 mM FLPAPrn were co-deposited so that the weight ratio (cgDBCzPA: 1,6 mM FLPAPrn) was 1: 0.03 and the thickness was 25 nm. In the light emitting layer 130, cgDBCzPA is a host material and 1.6 mM FLPAPrn is a fluorescent material (guest material).

As the light emitting layer 130 of the comparative light emitting element 1, BH-1 and 1,6 mM FLPAPrn are arranged so that the weight ratio (BH-1: 1,6 mM FLPApn) is 1: 0.03 and the thickness is 25 nm. Co-deposited. In the light emitting layer 130, BH-1 is a host material and 1.6 mM FLPAPrn is a fluorescent material (guest material).

As the light emitting layer 130 of the comparative light emitting element 2, the weight ratio (α, β-ADN: 1,6 mM FLPArun) of α, β-ADN and 1,6 mM FLPApn is 1: 0.03, and the thickness is 25 nm. It was co-deposited so as to be. In the light emitting layer 130, α and β-ADN are host materials, and 1.6 mM FLPAPrn is a fluorescent material (guest material).

<Measurement of fluorescence lifetime>
36 (A) and 36 (B) measure the fluorescence lifetime of the light emitting element (light emitting element 1 to light emitting element 3) and the comparative light emitting element (comparative light emitting element 1 and comparative light emitting element 2) according to one aspect of the present invention. It is the result of In the measurement of the fluorescence lifetime, the blue emission exhibited by the fluorescent material 1,6 mM FLPAPrn was observed.

A picosecond fluorescence lifetime measurement system (manufactured by Hamamatsu Photonics) was used for the measurement. In this measurement, in order to measure the lifetime of fluorescence emission in the light emitting element, a rectangular pulse voltage was applied to the light emitting element, and the light emission that was attenuated from the falling edge of the voltage was time-resolved and measured by a streak camera. The pulse voltage was applied at a cycle of 10 Hz, and the repeatedly measured data were integrated to obtain data having a high S / N ratio. The measurement was performed at room temperature (300 K) under the conditions that the applied pulse voltage was 3.5 V, the applied pulse time width was 100 μsec, the negative bias voltage was −5 V, and the measurement time range was 50 μsec. The measurement results are shown in FIGS. 36 (A) and 36 (B). In addition, in FIGS. 36A and 36B, the vertical axis shows the intensity standardized by the emission intensity in the state where carriers are constantly injected (when the pulse voltage is ON). The horizontal axis indicates the elapsed time from the fall of the pulse voltage.

The attenuation curves shown in FIGS. 36 (A) and 36 (B) were fitted by an exponential function. As a result, the fluorescence lifetimes τ of the light emitting element 1, the light emitting element 2, and the light emitting element 3 could be estimated to be 2.5 μsec, 3.5 μsec, and 2.3 μsec, respectively. Further, the fluorescence lifetimes τ of the comparative light emitting element 1 and the comparative light emitting element 2 could be estimated to be 4.7 μsec and 3.8 μsec, respectively. Usually, the lifetime of fluorescence emission is several nsec. Therefore, since it has a fluorescence lifetime of 1 μsec or more, fluorescence emission including a delayed fluorescent component is observed in all of the light emitting element 1, the light emitting element 2, the light emitting element 3, the comparative light emitting element 1, and the comparative light emitting element 2. It can be said that.

In the fluorescence measurement shown in FIGS. 36 (A) and 36 (B), the factors that cause delayed fluorescence are the inside of the light emitting element when the pulse voltage is OFF, in addition to the generation of singlet excitons by triplet-triplet annihilation (TTA). If carriers remain in the carrier, delayed fluorescence due to singlet exciton formation due to recombination of the residual carriers may occur. However, in this measurement, since the negative bias voltage (-5V) is applied under the conditions at the time of measurement, the measurement is performed under the condition that the recombination of the residual carriers is suppressed. Therefore, it can be said that the delayed fluorescence component shown in the measurement results of FIGS. 36 (A) and 36 (B) is due to light emission derived from triplet-triplet annihilation (TTA).

Next, the ratio of the delayed fluorescent component to the total emission component was calculated by fitting with an exponential function. As a result, the light emitting element 1, the light emitting element 2, and the light emitting element 3 had the ratios of delayed fluorescent components of 10%, 20%, and 12%, respectively, and the ratio of delayed fluorescence was high. On the other hand, in the comparative light emitting element 1 and the comparative light emitting element 2, the delayed fluorescence component was less than 1%, which was a result of a very low ratio of delayed fluorescence.

Therefore, it can be said that the light emitting element 1, the light emitting element 2, and the light emitting element 3 have higher TTA efficiency than the comparative light emitting element 1 and the comparative light emitting element 2.

<Operating characteristics of light emitting element>
Next, the light emitting characteristics of the produced light emitting element 1, light emitting element 2, light emitting element 3, comparative light emitting element 1, and comparative light emitting element 2 were measured. The measurement was performed at room temperature (atmosphere maintained at 25 ° C.).

Here, the light emitting characteristics of the light emitting element in the vicinity of 1000 cd / m ² are shown in Table 3 below. Further, the current efficiency-luminance characteristic of the light emitting element is shown in FIG. 37, the external quantum efficiency-luminance characteristic is shown in FIG. 38, and the brightness-voltage characteristic is shown in FIG. 39. Further, FIG. 40 shows an electroluminescent spectrum when a current is passed through the light emitting element at a current density of ^2.5 mA / cm ² .

As shown in FIG. 40, the electroluminescent spectrum peaks of the light emitting element 1, the light emitting element 2, the light emitting element 3, the comparative light emitting element 1 and the comparative light emitting element 2 are 462 nm, 461 nm, 464 nm, 464 nm, and 463 nm, respectively, and fluorescence. The blue emission exhibited by the material 1,6 mM FLPAprn was observed. That is, all of the light emitting elements exhibit blue light emission having a light emission spectrum peak in a wavelength band of 400 nm or more and 550 nm or less. Further, since the light emission exhibited by the fluorescent material was observed in the light emitting element 1 to the light emitting element 3, it can be said that the singlet excitation energy generated by the TTA is transferred from the host material to the fluorescent material.

Further, from the results of FIGS. 37, 38, and Table 3, it can be seen that the light emitting elements 1 to 3 exhibit higher current efficiency and external quantum efficiency than the comparative light emitting element 1 and the comparative light emitting element 2. In a fluorescent light emitting device that does not use TTA, the generation probability of singlet excitons generated by recombination of carriers (holes and electrons) injected from a pair of electrodes is 25% at the maximum, so that it is external to the outside. When the light extraction efficiency is 25%, the maximum external quantum efficiency is 6.25%. In the light emitting element 1 to the light emitting element 3, the external quantum efficiency is higher than 6.25%. This is based on the singlet excitons generated by TTA in addition to the singlet excitons generated by the recombination of carriers (holes and electrons) injected from the pair of electrodes in the light emitting elements 1 to 3. This is because light emission is obtained.

Therefore, as shown in the first embodiment, the energy of the third triplet excited state having the most stable structure of the third triplet excited state of the compound used as the host material is the energy of the third triplet excited state. It is preferably higher than the energy of the first triplet excited state having the most stable structure and lower than the energy of the second triplet excited state having the most stable structure of the third triplet excited state. Alternatively, the energy of the singlet excited state of the compound used as the host material is higher than the energy of the second triplet excited state having the most stable structure of the third triplet excited state, and the energy of the third triplet excited state is higher. The energy of the second triplet excited state having the most stable structure of the third triplet excited state is equal to or less than the energy of the third triplet excited state having the most stable structure of the third triplet excited state. It is preferably higher than the energy of the first triplet excited state having the most stable structure of. With such a configuration, a blue light emitting device having a delayed fluorescence component due to TTA and exhibiting high luminous efficiency can be manufactured.

Further, in the light emitting element 1, excellent light emitting efficiency having an external quantum efficiency of more than 9% is obtained. Therefore, the energy of the third triplet excited state having the most stable structure of the third triplet excited state is lower than the energy of the second triplet excited state having the most stable structure of the third triplet excited state. It can be said that it is more preferable, and it can be said that it is more preferable that the energy is 0.2 eV or more lower than the energy.

Further, as shown in FIGS. 39 and 3, the light emitting element 1 to the light emitting element 3 are driven by a voltage lower than that of the comparative light emitting element 1 and the comparative light emitting element 2. That is, by using a host material having a delayed fluorescence component due to TTA, a blue light emitting device driven by a low voltage can be manufactured.

As described above, by using a host material having a delayed fluorescence component due to TTA, a blue light emitting device with reduced power consumption can be manufactured.

<Measurement of singlet excitation energy and triplet excitation energy level>
In the fluorescence measurement shown in FIGS. 36 (A) and 36 (B), delayed fluorescence is caused by the reverse intersystem crossing from the triplet excited state to the singlet excited state, which exhibits thermally activated delayed fluorescence. There may be. In order for the inverse intersystem crossing to occur efficiently, the difference between the S1 level and the T1 level is preferably greater than 0 eV and 0.2 eV or less. Therefore, in order to confirm that the delayed fluorescence shown in FIGS. 36 (A) and 36 (B) is caused by TTA, the material used for the light emitting layer 130 of the light emitting device produced above has its S1 level and its S1 level. The T1 level was measured.

Measurements of the S1 and T1 levels were performed for CzPA, t-BuDNA, cgDBCzPA, and 1.6 mM FLPAPrn.

First, in order to estimate the S1 level, a thin film (about 50 nm) was formed on a quartz substrate by a vacuum vapor deposition method to prepare a thin film sample, and the absorption spectrum was measured. An ultraviolet-visible spectrophotometer (manufactured by JASCO Corporation, V550 type) was used for the measurement of the absorption spectrum. The absorption spectrum of quartz was subtracted from the spectrum of the measured sample. From the absorption spectrum data of the thin film, the absorption edge was obtained from the Tauc plot assuming a direct transition, and the S1 level was estimated with the absorption edge as the optical bandgap.

Next, phosphorescence measurement was performed to estimate the T1 level. In addition, since intersystem crossing is unlikely to occur in a fluorescent compound and light emission from the T1 level is weak, it may be difficult to measure the T1 level. Further, the substance used for the light emitting device, which is one aspect of the present invention, has a very high fluorescence quantum yield, and it is very difficult to directly observe phosphorescence by the low temperature PL measurement method in a thin film sample using a single material. .. Therefore, the phosphorescence measurement was performed by the method using the triplet sensitizer described below, and the T1 level was estimated.

A co-deposited film was prepared by adding Ir (ppy) ₃ as a triplet sensitizer to the material for measuring the T1 level, measured by the low temperature PL measurement method, and the T1 level was obtained from the measured phosphorescence spectrum. I estimated. A micro-PL device LabRAM HR-PL (HORIBA, Ltd.) was used for the measurement, a measurement temperature was 10 K, a He-Cd laser (325 nm) was used as the excitation light, and a CCD detector was used as the detector. By co-depositing Ir (ppy) ₃ , the probability of intersystem crossing of the fluorescent material to be measured is increased, and it becomes possible to measure phosphorescence emission from the fluorescent material, which is difficult without co-deposition.

The thin film was formed on a quartz substrate with a thickness of about 50 nm, and another quartz substrate was attached to the quartz substrate from the vapor deposition surface side in a nitrogen atmosphere, and then used for measurement.

Table 4 shows the measurement results of the S1 level and the measurement results of the T1 level estimated as described above.

From Table 4, the S1 level of CzPA, t-BuDNA, and cgDBCzPA is higher than the S1 level of the guest material exhibiting blue light emission, 1,6 mM FLPAPrn, and has a sufficient S1 level as a host material. I understand.

Further, from Table 4, it can be seen that the energy difference between the S1 level and the T1 level of CzPA, t-BuDNA, and cgDBCzPA is 0.5 eV or more. Thermally activated delayed fluorescence derived from the inverse intersystem crossing from the triplet excited state to the singlet excited state may be a factor that causes delayed fluorescence, but in order for the inverse intersystem crossing to occur efficiently, S1 quasi The difference between the rank and the T1 level is preferably greater than 0 eV and 0.2 eV or less. Therefore, in the materials used for the light emitting layer 130 of the light emitting device in the present embodiment and the first embodiment, it cannot be said that the delayed fluorescent component is derived from thermal activated delayed fluorescence, but is derived from TTA. It can be said that. Further, since the energy of the S1 level is less than twice the energy of the T1 level, it can be said that the energy can be transferred from the triplet excited state to the singlet excited state by TTA.

The spectral peaks of the fluorescence emission of the thin films of CzPA, t-BuDNA, and cgDBCzPA were 451 nm (2.75 eV), 442 nm (2.81 eV), and 442 nm (2.81 eV), respectively. Therefore, the energy conversion value difference between the peak wavelength of the fluorescence emission spectrum of CzPA, t-BuDNA and cgDBCzPA and the peak wavelength of the phosphorescence emission spectrum was 0.5 eV or more. For this reason as well, in the materials used for the light emitting layer 130 of the light emitting device in the present embodiment and the first embodiment, the delayed fluorescent component is not derived from thermal activated delayed fluorescence but from TTA. It can be said that there is. A PL-EL measuring device (manufactured by Hamamatsu Photonics Co., Ltd.) was used for measuring the fluorescence spectrum.

As described above, the configuration shown in this embodiment can be used in combination with other embodiments as appropriate.

In this example, a production example of a light emitting element (light emitting element 4) which is one aspect of the present invention is shown. The schematic cross-sectional view of the light emitting element produced in this embodiment is the same as that of the light emitting element shown in FIG. 1 (A). The details of the element structure are shown in Table 5. The compounds used in this example are the compounds shown in Embodiment 1 and Example 1.

<Manufacturing of light emitting element 4>
An ITSO film was formed on the substrate as the electrode 101 so as to have a thickness of 70 nm. The electrode area of the electrode 101 was 4 mm ² (2 mm × 2 mm).

Next, the EL layer 100 was formed on the electrode 101. As the hole injection layer 111, PCPPn and MoO ₃ were co-deposited so that the weight ratio (PCPPn: MoO ₃ ) was 1: 0.5 and the thickness was 10 nm. Further, as the hole transport layer 112, PCPPn was deposited so as to have a thickness of 30 nm.

Next, as the light emitting layer 130, cgDBCzPA and 1,6 mM FLPAPrn were co-deposited so that the weight ratio (cgDBCzPA: 1,6 mM FLPAPrn) was 1: 0.03 and the thickness was 25 nm. In the light emitting layer 130, cgDBCzPA is a host material and 1.6 mM FLPAPrn is a fluorescent material (guest material).

Further, cgDBCzPA and BPhen were sequentially vapor-deposited on the light emitting layer 130 as the electron transport layer 118 so as to have a thickness of 10 nm, respectively. Next, lithium fluoride (LiF) was deposited as an electron injection layer 119 so as to have a thickness of 1 nm.

Further, as the electrode 102, aluminum (Al) was formed so as to have a thickness of 200 nm.

Next, in the glove box having a nitrogen atmosphere, the light emitting element 4 was sealed by fixing the sealing substrate to the substrate on which the EL layer 100 was formed using an organic EL sealing material. The specific method is the same as that of the first embodiment. The light emitting element 4 was obtained by the above steps.

<Operating characteristics of light emitting element 4>
Next, the light emitting characteristics of the produced light emitting element 4 were measured. The measurement was performed at room temperature (atmosphere maintained at 23 ° C.).

Here, the light emitting characteristics of the light emitting element 4 near 1000 cd / m ² are shown in Table 6 below. Further, the current efficiency-luminance characteristic of the light emitting element 4 is shown in FIG. 41, the external quantum efficiency-luminance characteristic is shown in FIG. 42, and the brightness-voltage characteristic is shown in FIG. 43. Further, FIG. 44 shows an electroluminescent spectrum when a current is passed through the light emitting element 4 at a current density of ^2.5 mA / cm ² . Further, FIG. 45 shows the result of measuring the angle distribution of the light emitted by the light emitting element 4.

As shown in FIG. 44, the electroluminescence spectrum peak of the light emitting element 4 was 465 nm, and the blue emission exhibited by the fluorescent material of 1,6 mM FLPAPrn was observed. That is, the light emitting element 4 exhibits blue light emission having a light emission spectrum peak in a wavelength band of 400 nm or more and 550 nm or less. Further, since the light emission exhibited by the fluorescent material was observed in the light emitting element 4, it can be said that the singlet excitation energy generated by the TTA is transferred from the host material to the fluorescent material.

Further, from the results of FIGS. 41, 42, and Table 6, it can be seen that the light emitting device 4 exhibits high current efficiency and external quantum efficiency efficiency. In the light emitting device 4, an excellent efficiency in which the external quantum efficiency exceeds 13% is obtained. This is because the light emitting device 4 emits light based on the singlet excitons generated by TTA in addition to the singlet excitons generated by the recombination of carriers (holes and electrons) injected from the pair of electrodes. This is because it has been obtained.

As a result of measuring the emission angle distribution of the light emitting element 4, as shown in FIG. 45, the difference between the emission angle distribution of the light emitting element 4 and the perfect diffusion surface (also referred to as Lambertian or Lambertian) (also referred to as Lambertian ratio). ) Was 97.5%. The external quantum efficiency shown in FIGS. 42 and 6 is the product of the external quantum efficiency calculated by assuming the Lambersian light distribution from the measurement result of the current efficiency in the front and the Lambersian ratio, and is true in all directions. It is a value that estimates the external quantum efficiency.

Further, as shown in FIGS. 43 and 6, the light emitting element 4 is driven by a low voltage. That is, by using a host material having a delayed fluorescence component due to TTA, a blue light emitting device driven by a low voltage can be manufactured.

Next, the measurement result of the reliability test of the light emitting element 4 is shown in FIG. In the reliability test, the initial brightness of the light emitting element 4 was set to 5000 cd / m ² , and the light emitting element 4 was driven under a condition of constant current density.

As a result, the time of deterioration to 90% of the initial brightness (LT90) was 180 hours, and the light emitting element 4 showed excellent reliability.

Therefore, as shown in the first embodiment, the energy of the lowest singlet excited state of the compound used as the host material is higher than the energy of the second triplet excited state having the most stable structure of the third triplet excited state. A second triplet excited state that is high and has the most stable structure of the third triplet excited state and is less than or equal to the energy of the third triplet excited state and has the most stable structure of the third triplet excited state. Is preferably higher than the energy of the first triplet excited state having the most stable structure of the third triplet excited state.

As described above, by using the host material having a delayed fluorescence component due to TTA, it is possible to manufacture a blue light emitting device having reduced power consumption and excellent reliability. In addition, the configuration shown in this embodiment can be used in combination with other embodiments as appropriate.

In this embodiment, a production example of a light emitting element (light emitting element 5 to a light emitting element 11) according to one aspect of the present invention is shown. A schematic cross-sectional view of the light emitting device produced in this embodiment is shown in FIG. 47, and details of the device structure are shown in Tables 8 to 10, respectively. The structures and abbreviations of the compounds used are shown below. For other compounds, the first embodiment and the first embodiment may be referred to.

<Manufacturing of light emitting elements 5 to 11>
<< Fabrication of light emitting element 5 >>
An alloy film of silver, palladium, and copper (also referred to as Ag-Pd-Cu film or APC) was formed on the substrate 510 as the conductive layer 501a constituting the electrode 501 so as to have a thickness of 100 nm. Next, as the conductive layer 501b in contact with the conductive layer 501a, an ITSO film was formed so as to have a thickness of 85 nm. Through the above steps, an electrode 501 having a function of reflecting light was formed. The electrode area of the electrode 501 was 4 mm ² (2 mm × 2 mm).

Next, as a hole injection layer 531 on the electrode 501, PCPPn and MoO ₃ are combined so that the weight ratio (PCPPn: MoO ₃ ) is 1: 0.5 and the thickness is 20 nm. Vapor deposition. Further, as the hole transport layer 532, PCPPn was deposited so as to have a thickness of 15 nm.

Next, as the light emitting layer 521, cgDBCzPA and 1,6 mM FLPAPrn were co-deposited so that the weight ratio (cgDBCzPA: 1,6 mM FLPAPrn) was 1: 0.03 and the thickness was 25 nm. In the light emitting layer 521, cgDBCzPA is the host material and 1.6 mM FLPAPrn is the fluorescent material (guest material).

Further, cgDBCzPA and BPhen were sequentially vapor-deposited on the light emitting layer 521 as the electron transport layer 533 so as to have thicknesses of 10 nm and 15 nm, respectively.

Next, lithium oxide (Li ₂ O) and copper phthalocyanine (abbreviation: CuPc) were sequentially deposited on the electron transport layer 533 as the electron injection layer 534 so as to have a thickness of 0.1 nm and 2 nm, respectively.

Next, as the charge generation layer 535 that also serves as the hole injection layer, 4,4', 4''-(benzene-1,3,5-triyl) tri (dibenzothiophene) (abbreviation: DBT3P-II) and MoO ₃ was co-deposited so that the weight ratio (DBT3P-II: MoO ₃ ) was 1: 0.5 and the thickness was 10 nm.

Next, as the hole transport layer 537, 4-phenyl-4'-(9-phenylfluorene-9-yl) triphenylamine (abbreviation: BPAFLP) was deposited so as to have a thickness of 15 nm.

Next, as the light emitting layer 522, 2- [3'-(dibenzothiophen-4-yl) biphenyl-3-yl] dibenzo [f, h] quinoxaline (abbreviation: 2mDBTBPDBq-II) and N- (1,1) '-Biphenyl-4-yl) -N- [4- (9-phenyl-9H-carbazole-3-yl) phenyl] -9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), (Acetylacetonato) bis (6-tert-butyl-4-phenylpyrimidinato) iridium (III) (abbreviation: Ir (tBuppm) ₂ (acac)) and weight ratio (2mDBTBPDBq-II: PCBBiF: Ir (abbreviation: Ir (tBuppm) ₂ (acac)) tBuppm) ₂ (acac)) was co-deposited so that it was 0.8: 0.2: 0.06 and the thickness was 20 nm, followed by 2mDBTBPDBq-II, PCBBiF, and bis [ 2- (5- (2,6-dimethylphenyl) -3- (3,5-dimethylphenyl) -2-pyrazinyl-κN) -4,6-dimethylphenyl-κC] (2,2,6,6- Tetramethyl-3,5-heptandionat-κ ² O, O') Iridium (III) (abbreviation: Ir (dmdppr-dmp) ₂ (dpm)) and weight ratio (2mDBTBPDBq-II: PCBBiF: Ir (dmdppr-) Co-deposited so that dmp) ₂ (dpm)) was 0.8: 0.2: 0.05 and the thickness was 10 nm, followed by 2mDBTBPDBq-II, PCBBiF, and Ir (dmp) ₂ (dpm)). tBuppm) ₂ (acac) and the weight ratio (2mDBTBPDBq-II: PCBBiF: Ir (tBuppm) ₂ (acac)) to 0.8: 0.2: 0.05 and a thickness of 10 nm. It was co-deposited so as to be.

Next, 2mDBTBPDBq-II and 2,9-bis (naphthalene-2-yl) -4,7-diphenyl-1,10-phenanthroline (abbreviation: NBPhen) are placed on the light emitting layer 522 as an electron transport layer 538. , Sequentially deposited to have thicknesses of 30 nm and 15 nm, respectively. Further, lithium fluoride (LiF) was deposited on the electron transport layer 538 as an electron injection layer 539 so as to have a thickness of 1 nm.

Next, silver (Ag) and magnesium (Mg) were co-deposited on the electron injection layer 539 as an electrode 502 so as to have a thickness of 15 nm, and an ITO film was further formed so as to have a thickness of 70 nm. .. Through the above steps, an electrode 502 having a function of reflecting light and a function of transmitting light was formed. The co-deposited film of Ag and Mg was vapor-deposited so that the volume ratio (Ag: Mg) was 1: 0.1.

Through the above steps, a pair of electrodes and an EL layer formed on the substrate 510 were formed. In the film forming process described above, all the vapor deposition was carried out by the resistance heating method. The ITO film of the electrode 502 was formed by a sputtering method.

Further, on the sealing substrate 512 of the light emitting element 5, a red color filter (CF Red) was formed as an optical element 514 with a thickness of 2.1 μm.

Next, the light emitting element 5 was sealed by fixing the sealing substrate 512 on the substrate 510 using an organic EL sealing material in a glove box having a nitrogen atmosphere. Specifically, a sealing material is applied around the EL layer formed on the substrate 510, the substrate 510 and the sealing substrate 512 are bonded to each other, and ultraviolet light having a wavelength of 365 nm is irradiated at 6 J / cm ² to reach 80 ° C. Heat-treated for 1 hour at. The light emitting element 5 was obtained by the above steps.

<< Fabrication of light emitting element 6 >>
The light emitting element 6 differs from the above-mentioned manufacturing of the light emitting element 5 only in the steps of the hole injection layer 531 and the light emitting layer 522, and the other steps are the same manufacturing methods as those of the light emitting element 5.

As the hole injection layer 531 on the electrode 501, PCPPn and MoO ₃ were co-deposited so that the weight ratio (PCPPn: MoO ₃ ) was 1: 0.5 and the thickness was 10 nm.

As the light emitting layer 522, 2mDBTBPDBq-II, PCBBiF, Ir (tBuppm) ₂ (acac), and the weight ratio (2mDBTBPDBq-II: PCBBiF: Ir (tBuppm) ₂ (acac)) are 0.8: 0.2. Co-deposited to 0.06 and 20 nm in thickness, followed by 2mDBTBPDBq-II, PCBBiF and screw {4,6-dimethyl-2- [5- (2,6) -Dimethylphenyl) -3- (3,5-dimethylphenyl) -2-pyrazinyl-κN] phenyl-κC} (2,4-pentandionato-κ ² O, O') Iridium (III) (abbreviation: Ir (Dmdppr-dmp) ₂ (acac)), bis {4,6-dimethyl-2- [5- (2,6-dimethylphenyl) -3- (3,5-dimethylphenyl) -2-pyrazinyl-κN] Phenyl-κC} (2,8-dimethyl-4,6-nonandionato-κ ² O, O') Iridium (III) (abbreviation: Ir (dmdppr-dmp) ₂ (divm)) and weight ratio (2mDBTBPDBq-). II: PCBiF: Ir (dmdppr-dmp) ₂ (divm)) co-deposited to 0.8: 0.2: 0.05 and thickness to 10 nm, followed by 2mDBTBPDBq- and II, and _{PCBBiF, Ir (tBuppm) 2 (} acac) and the weight ratio (2mDBTBPDBq-II: PCBBiF: Ir (tBuppm) 2 (acac)) is 0.8: 0.2: so that 0.05 And co-deposited so that the thickness was 10 nm.

<< Fabrication of light emitting element 7 >>
The light emitting element 7 is different from the above-mentioned manufacturing of the light emitting element 5 in the steps of the conductive layer 501b, the hole injection layer 531 and the optical element 514, and the other steps are the methods for manufacturing the light emitting element 5.

As the conductive layer 501b constituting the electrode 501, an ITSO film was formed so as to have a thickness of 45 nm.

As a hole injection layer 531 on the electrode 501, PCPPn and MoO ₃ were co-deposited so that the weight ratio (PCPPn: MoO ₃ ) was 1: 0.5 and the thickness was 10 nm.

Further, on the sealing substrate 512 of the light emitting element 7, a green color filter (CF Green) was formed as an optical element 514 with a thickness of 1.2 μm.

<< Fabrication of light emitting element 8 >>
The light emitting element 8 was different from the above-mentioned manufacturing of the light emitting element 7 in the process of the hole injection layer 531. The other steps were the methods for manufacturing the light emitting element 7.

As a hole injection layer 531 on the electrode 501, PCPPn and MoO ₃ were co-deposited so that the weight ratio (PCPPn: MoO ₃ ) was 1: 0.5 and the thickness was 15 nm.

<< Fabrication of light emitting element 9 >>
The light emitting element 9 is different from the above-mentioned manufacturing of the light emitting element 6 in the steps of the conductive layer 501b, the hole injection layer 531 and the optical element 514, and the other steps are the methods for manufacturing the light emitting element 6.

As the conductive layer 501b constituting the electrode 501, an ITSO film was formed so as to have a thickness of 45 nm.

As a hole injection layer 531 on the electrode 501, PCPPn and MoO ₃ were co-deposited so that the weight ratio (PCPPn: MoO ₃ ) was 1: 0.5 and the thickness was 10 nm.

Further, on the sealing substrate 512 of the light emitting element 9, a green color filter (CF Green) was formed as an optical element 514 with a thickness of 1.2 μm.

<< Fabrication of light emitting element 10 >>
The light emitting element 10 is different from the above-mentioned manufacturing of the light emitting element 5 in the steps of the conductive layer 501b, the hole injection layer 531 and the optical element 514, and the other steps are the methods for manufacturing the light emitting element 5.

As the conductive layer 501b constituting the electrode 501, an ITSO film was formed so as to have a thickness of 110 nm.

As a hole injection layer 531 on the electrode 501, PCPPn and MoO ₃ were co-deposited so that the weight ratio (PCPPn: MoO ₃ ) was 1: 0.5 and the thickness was 15 nm.

Further, on the sealing substrate 512 of the light emitting element 7, a blue color filter (CF Blue) was formed as an optical element 514 with a thickness of 0.8 μm.

<< Fabrication of light emitting element 11 >>
The light emitting element 11 is different from the above-mentioned manufacturing of the light emitting element 6 in the steps of the conductive layer 501b, the hole injection layer 531 and the optical element 514, and the other steps are the methods for manufacturing the light emitting element 6.

As the conductive layer 501b constituting the electrode 501, an ITSO film was formed so as to have a thickness of 115 nm.

As a hole injection layer 531 on the electrode 501, PCPPn and MoO ₃ were co-deposited so that the weight ratio (PCPPn: MoO ₃ ) was 1: 0.5 and the thickness was 5 nm.

Further, on the sealing substrate 512 of the light emitting element 9, a blue color filter (CF Blue) was formed as an optical element 514 with a thickness of 0.8 μm.

<Characteristics of light emitting elements 5 to 11>
The current efficiency-luminance characteristics of the manufactured light emitting elements 5 to 11 are shown in FIGS. 48 and 49. The brightness-voltage characteristics are shown in FIGS. 50 and 51. The measurement of each light emitting element was performed at room temperature (atmosphere maintained at 23 ° C.).

Table 11 shows the element characteristics of the light emitting element 5 to the light emitting element 11 in the vicinity of 1000 cd / m ² .

Further, FIGS. 52 and 53 show electroluminescent spectra (EL spectra) when a current is passed through the light emitting elements 5 to 11 at a current density of ^2.5 mA / cm ² .

As shown in FIGS. 48 to 53 and Table 11, the light emitting element 5 and the light emitting element 6 obtained red light emission with high current efficiency and high color purity. The light emitting elements 7 to 9 obtained green light emission with high current efficiency and high color purity. The light emitting element 10 and the light emitting element 11 obtained blue light emission with high current efficiency and high color purity.

<Angle dependence of chromaticity of light emitting element>
Next, FIG. 54 shows the results of measuring the electroluminescence spectrum of the light emitting element 10 from the front direction (0 °) to the oblique direction (70 °). Further, FIG. 55 shows the results of measuring the electroluminescence spectra of the light emitting element 10 and the light emitting element (light emitting element 12) having different configurations of the optical element 514 from the front direction (0 °) to the oblique direction (70 °). As the optical element 514 of the light emitting element 12, a blue color filter (CF Blue) was formed with a thickness of 1.5 μm.

As shown in FIGS. 54 and 55, in the light emitting element 10, light emission in the vicinity of 550 nm is strongly exhibited at 70 ° in the oblique direction. On the other hand, in the light emitting element 12, the light emission near 550 nm is weaker than that of the light emitting element 10 at 70 ° in the oblique direction.

Further, FIG. 56 shows the result of calculating the chromaticity difference Δu'v'from the front direction in the oblique direction with respect to the viewing angle dependence of the chromaticity of the light emitting element 10 and the light emitting element 12.

As shown in FIG. 56, the light emitting element 12 has a chromaticity difference Δu'v'less than 0.2 at an angle of 0 ° to 70 °, and the result is that the viewing angle dependence of the chromaticity is smaller than that of the light emitting element 10. Obtained. That is, the light emitting element 12 has a better angle dependence of chromaticity than the light emitting element 10.

<Estimation of power consumption of display device using light emitting element>
Next, the power consumption of the display device when the display device was manufactured was estimated using the manufactured light emitting elements 5 to 11.

In a display device with a display area aspect ratio of 16: 9, a diagonal size of 4.5 inches, and an area of 55.82 cm ² , the power consumption of the display device is estimated assuming an aperture ratio of 35%. It was. Table 12 shows the characteristics of the light emitting element and the display device when used in the display device of the specifications. In this embodiment, the display device using the light emitting elements 5, 7 and 10 as the display element is the display device 1, and the display device using the light emitting elements 5, 8 and 10 as the display element is the display device 2 and emits light. A display device using elements 6, 9 and 11 as display elements is displayed as a display device 3, a display device using light emitting elements 5, 7 and 12 as display elements is displayed as a display device 4, and light emitting elements 5, 8 and 12 are displayed. The display device used as the element is referred to as a display device 5, respectively.

As shown in Table 12, when the light emitting elements 5, 7, and 10 are used as the display elements of the display device having the above specifications (display device 1), the brightness of the display element having the structure of the light emitting element 5 is 675 cd / m ² . When the brightness of the display element having the structure of the light emitting element 7 is 1631 cd / m ² and the brightness of the display element having the structure of the light emitting element 10 is 266 cd / m ² , the color temperature is 6500 K and white (chromaticity (x, y)). (0.313, 0.329)) could be displayed on the entire display area at 300 cd / m ² , and the power consumption of these display elements could be estimated to be 427 mW at this time. In addition, the area ratio (compared to NTSC) of the CIE1976 chromaticity that can be displayed by the display device to the color gamut standard established by the National Television Broadcasting System Standardization Committee (NTSC) was estimated to be 102%.

When the light emitting elements 5, 8 and 10 are used as the display elements of the display device having the above specifications (display device 2), the brightness of the display element having the structure of the light emitting element 5 is 576 cd / m ² , and the light emitting element 8 When the brightness of the display element having a structure is 1728 cd / m ² and the brightness of the display element having a structure of the light emitting element 10 is 267 cd / m ² , the white color (chromaticity (x, y)) of 6500 K is (0. 313, 0.329)) could be displayed on the entire display area at 300 cd / m ² , and the power consumption of these display elements could be estimated to be 393 mW at this time. The NTSC ratio was estimated to be 95%.

When the light emitting elements 6, 9, and 11 are used as the display elements of the display device having the above specifications (display device 3), the brightness of the display element having the structure of the light emitting element 6 is 658 cd / m ² , and the light emitting element 9 is used. When the brightness of the display element having a structure is 1620 cd / m ² and the brightness of the display element having a structure of the light emitting element 11 is 294 cd / m ² , the white color (chromaticity (x, y)) of 6500 K is (0. 313, 0.329)) could be displayed on the entire display area at 300 cd / m ² , and at this time, the power consumption of these display elements could be estimated to be 476 mW. The NTSC ratio was estimated to be 98%.

When the light emitting elements 5, 7, and 12 are used as the display elements of the display device having the above specifications (display device 4), the brightness of the display element having the structure of the light emitting element 5 is 697 cd / m ² , and the light emitting element 7 When the brightness of the display element having a structure is 1640 cd / m ² and the brightness of the display element having a structure of the light emitting element 10 is 234 cd / m ² , the white color (chromaticity (x, y)) of 6500 K is (0. 313, 0.329)) could be displayed on the entire display area at 300 cd / m ² , and at this time, the power consumption of these display elements could be estimated to be 447 mW. The NTSC ratio was estimated to be 106%.

When the light emitting elements 5, 8 and 12 are used as the display elements of the display device having the above specifications (display device 5), the brightness of the display element having the structure of the light emitting element 5 is 598 cd / m ² , and the light emitting element 8 When the brightness of the display element having a structure is 1739 cd / m ² and the brightness of the display element having a structure of the light emitting element 10 is 235 cd / m ² , the white color (chromaticity (x, y)) of 6500 K is (0. 313, 0.329)) could be displayed on the entire display area at 300 cd / m ² , and at this time, the power consumption of these display elements could be estimated to be 413 mW. The NTSC ratio was estimated to be 100%.

As described above, it has been shown that the display element having the structure of the light emitting element 5 to the light emitting element 12 is a display element with reduced power consumption. Further, it was shown that a display device having reduced power consumption can be provided by using the display element as described above.

<Reliability test results>
Next, the results of the reliability test of the light emitting element 5, the light emitting element 7, the light emitting element 8, and the light emitting element 10 are shown in FIGS. 57 to 59. The initial brightness of the light emitting element in the reliability test was set to the initial brightness assuming the display device 1 and the display device 2, and the light emitting element was driven under a constant current density condition. In addition, reliability tests were conducted on each of the two light emitting elements.

Further, in the light emitting element 5, the light emitting elements tested at the initial brightness of the display device 1 (initial brightness 675 cd / m ² ) are the light emitting element 5 (1) and the light emitting element 5 (2), and the initial brightness of the display device 2. The light emitting elements tested at (initial brightness 576 cd / m ² ) were the light emitting element 5 (3) and the light emitting element 5 (4). Further, in the light emitting element 7, the light emitting elements tested at the initial brightness of the display device 1 (initial brightness 1631 cd / m ² ) were designated as the light emitting element 7 (1) and the light emitting element 7 (2). Further, in the light emitting element 8, the light emitting elements tested at the initial brightness of the display device 2 (initial brightness 1728 cd / m ² ) were designated as the light emitting element 8 (1) and the light emitting element 8 (2). Further, in the light emitting element 10, the light emitting elements tested at the initial brightness (initial brightness 267 cd / m ² ) of the display device 1 and the display device 2 were designated as the light emitting element 10 (1) and the light emitting element 10 (2).

The results of the reliability tests of the light emitting elements 5 (1), (2), (3) and (4) are shown in FIGS. 57 (A) and 57 (B), and the light emitting elements 7 (1) and (2) and the light emitting elements 8 (1) and (2) are shown. The reliability test results of the light emitting elements 10 (1) and (2) are shown in FIGS. 58 (A) and 58 (B), respectively. 57 (A), 58 (A), and 59 (A) show the time change of the normalized luminance when the initial luminance is 100%, and FIGS. 58 (B) and 59 (B) show the time change of the normalized luminance. , And FIG. 59 (B) show the voltage change when the initial voltage is 0V.

As shown in FIGS. 57 to 59, the light emitting elements 5, 7, 8 and 10, which are the light emitting elements of one aspect of the present invention, all have a brightness of 95% or more after 800 hours, and the brightness deterioration is small. Moreover, the voltage rise after 800 hours was 0.2 V or less, and the voltage change was small, and the light emitting element was excellent in reliability. That is, the light emitting element of one aspect of the present invention is suitable as a display element of a display device.

As described above, by using the configuration of one aspect of the present invention, it is possible to provide a light emitting device that exhibits high current efficiency and exhibits blue light emission with high color purity. Further, by using the light emitting element having the configuration of one aspect of the present invention, it is possible to provide a display device having excellent reliability. Further, by using the light emitting element having the configuration of one aspect of the present invention, it is possible to provide a display device having low power consumption and high color purity.

As described above, the configuration shown in this embodiment can be used in combination with other examples and embodiments as appropriate.

100 EL layer 101 Electrode 101a Conductive layer 101b Conductive layer 101c Conductive layer 102 Electrode 103 Electrode 103a Conductive layer 103b Conductive layer 104 Electrode 104a Conductive layer 104b Conductive layer 111 Hole injection layer 112 Hole transport layer 113 Electron transport layer 114 Electron injection layer 115 Charge generation layer 116 Hole injection layer 117 Hole transport layer 118 Electron transport layer 119 Electron injection layer 120 Light emitting element 123B Light emitting layer 123G Light emitting layer 123R Light emitting layer 130 Light emitting layer 131 Host material 132 Guest material 140 Partition 151 Triple-term excited state 152 Triple-term excited state 153 Triple-term excited state 160 Light-emitting layer 161 Triple-term excited state 162 Triple-term excited state 163 Triple-term excited state 164 Triple-term excited state 170 Light-emitting layer 170a Light-emitting layer 170b Light-emitting layer 171 Triple-term excited state 172 Triple-term Excited state 173 Triple-term excited state 174 Triple-term excited state 181 Triple-term excited state 182 Triple-term excited state 183 Triple-term excited state 184 Triple-term excited state 191 Triple-term excited state 192 Triple-term excited state 193 Triple-term excited state 194 Triple-term Excited state 200 Substrate 220 Substrate 221B Region 221G Region 221R Region 222B Region 222G Region 222R Region 223 Shading layer 224B Optical element 224G Optical element 224R Optical element 250 Light emitting element 252 Light emitting element 254 Light emitting element 256 Light emitting element 301_1 Wiring 301_5 Wiring 301_6 302_1 Wiring 302_1 Wiring 303_1 Transistor 303_6 Transistor 303_7 Transistor 304 Capacitive element 304_1 Capacitive element 304_1 Capacitive element 305 Light emitting element 306_1 Wiring 306_3 Wiring 307_1 Wiring 307_3 Wiring 308_1 Transistor 308_1 Transistor 309_1 Wiring 309_1 Wiring 309_1 Wiring 3 Electrode 402 Electrode 411 Hole injection layer 412 Hole transport layer 413 Electron transport layer 414 Electron injection layer 416 Hole injection layer 417 Hole transport layer 418 Electron transport layer 419 Electron injection layer 420 Light emitting layer 421 Host material 422 Guest material 430 Light emission Layer 431 Host material 431_1 Organic compound 431_2 Organic compound 432 Guest material 441 Light emitting unit 442 Optical unit 445 Charge generation layer 450 Light emitting element 452 Light emitting element 501 Electrode 502 Electrode 501a Conductive layer 501b Conductive layer 510 Substrate 512 Sealing substrate 514 Optical element 521 Light emitting layer 522 Light emitting layer 531 Hole injection layer 532 Hole transport layer 533 Electron transport Layer 534 Electron injection layer 535 Charge generation layer 537 Hole transport layer 538 Electron transport layer 538 Electron injection layer 600 Display device 601 Signal line drive circuit unit 602 Pixel unit 603 Scan line drive circuit unit 604 Sealing substrate 605 Sealing material 607 Area 608 Wiring 609 FPC
610 Element board 611 Transistor 612 Transistor 613 Lower electrode 614 Partition 616 EL layer 617 Upper electrode 618 Light emitting element 621 Optical element 622 Light-shielding layer 623 Transistor 624 Transistor 801 Pixel circuit 802 Pixel 804 Drive circuit 804a Scan line drive circuit 804b Signal line drive Circuit 806 Protection circuit 807 Terminal 852 Transistor 854 Transistor 862 Capacitive element 872 Light emitting element 1001 Substrate 1002 Underground insulating film 1003 Gate insulating film 1006 Gate electrode 1007 Gate electrode 1008 Gate electrode 1020 Interlayer insulating film 1021 Interlayer insulating film 1022 Electrode 1024B Lower electrode 1024G Lower electrode 1024R Lower electrode 1024Y Lower electrode 1025 Partition 1026 Upper electrode 1028 EL layer 1029 Sealing layer 1031 Sealing substrate 1032 Sealing material 1033 Base material 1034B Colored layer 1034G Colored layer 1034R Colored layer 1034Y Colored layer 1035 Light-shielding layer 1036 Overcoat layer 1037 Interlayer insulating film 1040 Pixel part 1041 Drive circuit part 1042 Peripheral part 2000 Touch panel 2001 Touch panel 2501 Display device 2502R Pixel 2502t Transistor 2503c Capacitive element 2503g Scanning line drive circuit 2503s Signal line drive circuit 2503t Transistor 2509 FPC
2510 Substrate 2510a Insulation layer 2510b Flexible substrate 2510c Adhesive layer 2511 Wiring 2519 Terminal 2521 Insulation layer 2528 Partition 2550R Light emitting element 2560 Sealing layer 2567BM Light shielding layer 2567p Antireflection layer 2567R Colored layer 2570 Substrate 2570a Insulation layer 2570b Flexible substrate 2570c Adhesive layer 2580R Light emitting module 2590 Board 2591 Electrode 2592 Electrode 2593 Insulation layer 2594 Wiring 2595 Touch sensor 2597 Adhesive layer 2598 Wiring 2599 Connection layer 2601 Pulse voltage output circuit 2602 Current detection circuit 2603 Capacity 2611 Transistor 2612 Transistor 2613 Transistor 2621 Electrode 2622 Electrode 3000 Device 3001 Board 3003 Board 3005 Light emitting element 3007 Sealing area 3009 Sealing area 3011 Area 3013 Area 3014 Area 3015 Board 3016 Board 3018 Drying agent 3054 Display 3500 Multi-function terminal 3502 Housing 3504 Display 3506 Camera 3508 Lighting 3600 Light 3602 Body 3608 Lighting 3610 Speaker 8000 Display module 8001 Top cover 8002 Bottom cover 8003 FPC
8004 Touch sensor 8005 FPC
8006 Display device 8009 Frame 8010 Printed board 8011 Battery 8501 Lighting device 8502 Lighting device 8503 Lighting device 8504 Lighting device 9000 Housing 9001 Display unit 9003 Speaker 9005 Operation key 9006 Connection terminal 9007 Sensor 9008 Microphone 9050 Operation button 9051 Information 9052 Information 9053 Information 9054 Information 9055 Hinge 9100 Mobile information terminal 9101 Mobile information terminal 9102 Mobile information terminal 9200 Mobile information terminal 9201 Mobile information terminal

Claims (3)

A light emitting device having a light emitting layer between a pair of electrodes.
The light emitting layer has an organic compound and a pyrene diamine compound.
The organic compound has a first skeleton and a second skeleton.
The second skeleton is a naphthyl skeleton.
The light emitted by the light emitting layer has a delayed fluorescence component due to triplet-triplet annihilation.
The first triplet excited state in the organic compound is the excited state having the lowest excitation energy level in the organic compound.
The first triplet excited state has a molecular orbital in the first skeleton.
The second triplet excited state in the organic compound has the lowest excitation energy level among the triplet excited states having a molecular orbital in the second skeleton and a molecular orbital in the second skeleton. It is a triplet excited state with
The third triplet excited state in the organic compound is a triplet excited state having a molecular orbital in the first skeleton and having a molecular orbital in the first skeleton other than the first triplet excited state. It is a triplet excited state with the lowest excitation energy level among the states.
The single-term excited state having the lowest excitation energy level in the organic compound is higher than the excitation energy level of the second triple-term excited state and equal to or lower than the excitation energy level of the third triple-term excited state. Has an excitation energy level that is
Light emitting device. In claim 1 ,
The energy of the singlet excited state is higher than the energy of the second triplet excited state of the first structure when the most stable structure in the third triplet excited state is the first structure. Higher and less than or equal to the energy of the third triplet excited state of the first structure.
Light emitting device. In claim 1 ,
The energy conversion value of the absorption edge in the absorption spectrum of the organic compound is the second triplet when the most stable structure of the third triplet excited state is the first structure and the first structure. It is higher than the energy of the term excited state and less than or equal to the energy of the third triplet excited state in the case of the first structure.
Light emitting device.