JP2022044821A - Light-emitting element, illuminating device, light-emitting device, display device, and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting element using a plurality of light emitting dopant, which has high light-emitting efficiency, and provide each of a light-emitting device, a light-emitting module, a light-emitting display device, an electronic apparatus, and an illuminating device, in which a power consumption is reduced by using the light-emitting element as mentioned.

SOLUTION: By focusing on a Foerster mechanism as one of an intermolecular energy transfer mechanism, an energy transfer in the Foerster mechanism can be efficiently performed by overlapping a light emission wavelength of an energy giving side molecule and a peak having a local maximum on the longest wavelength side in a graph obtained by multiplying an absorption spectrum on the side of receiving energy by a wavelength to the fourth power.

SELECTED DRAWING: Figure 2

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to a light emitting element, a display device, a light emitting device, an electronic device, and a lighting device using an organic compound as a light emitting substance.

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
A layer (EL layer) containing a luminescent substance is sandwiched between a pair of electrodes. By applying a voltage to this element, light emission from a light emitting substance can be obtained.

Since such a light emitting element is a self-luminous type, it has advantages such as higher pixel visibility than a liquid crystal display and no need for a backlight, and is considered to be suitable as a flat panel display element. Further, it is a great advantage that the display using such a light emitting element can be manufactured thin and lightweight. Another feature is that the response speed is extremely fast.

Since these light emitting elements can form a light emitting layer in a film shape, light emission can be obtained in a planar shape. Therefore, a device having a large area can be easily formed. This is a feature that is difficult to obtain with a point light source represented by an incandescent lamp or an LED, or a line light source represented by a fluorescent lamp, and therefore has high utility value as a surface light source that can be applied to lighting or the like.

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

There are two types of excited states formed by organic compounds: singlet excited state and triplet excited state. Emission from the singlet excited state (S ^* ) is fluorescent, and emission from the triplet excited state (T ^* ) is emitted. It is called phosphorescent. The statistical generation ratio of the light emitting element is S ^* : T ^* =.
It is believed to be 1: 3.

In a compound that emits light from a singlet excited state (hereinafter referred to as a fluorescent compound), usually no light emission (phosphorescence) from the triplet excited state is observed at room temperature, only light emission (fluorescence) from the singlet excited state. Is observed. Therefore, the theoretical limit of the internal quantum efficiency (ratio of photons generated to injected carriers) in a light emitting device using a fluorescent compound is S ^* : T ^* =.
It is set to 25% based on the fact that it is 1: 3.

On the other hand, if a compound that emits light from the triplet excited state (hereinafter referred to as a phosphorescent compound) is used,
Emission (phosphorescence) from the triplet excited state is observed. In addition, phosphorescent compounds are intersystem crossings (
The internal quantum efficiency is 1 because the transition from the singlet excited state to the triplet excited state is likely to occur.
It is theoretically possible up to 00%. That is, higher luminous efficiency than fluorescent compounds can be realized. For this reason, in recent years, in order to realize a highly efficient light emitting device, a light emitting device using a phosphorescent compound has been actively developed.

Patent Document 1 discloses a white light emitting device having a light emitting region including a plurality of light emitting dopants, and the light emitting dopant emits phosphorescence.

Special Table 2004-522276 Publication No.

Although it is a phosphorescent compound that can theoretically have an internal quantum efficiency of 100%, it is difficult to achieve high efficiency without optimizing the device structure and combination with other materials. In particular, in a light emitting element that uses a plurality of types of phosphorescent compounds of different bands (emission colors) as light emitting dopants, it is not only necessary to consider energy transfer but also high efficiency without optimizing the efficiency of the energy transfer itself. It is difficult to obtain efficient light emission. In fact, in Patent Document 1, even if the light emitting dopant is a phosphorescent element, its external quantum efficiency is about 3 to 4%. It must be said that the internal quantum efficiency is considered to be 20% or less even if the light extraction efficiency is taken into consideration, which is a low value for a phosphorescent light emitting device.

In addition to improving the luminous efficiency, in a multicolor light emitting device using dopants of different emission colors, it is necessary that the dopants of each emission color emit light in a well-balanced manner. It is not easy to maintain the luminous balance of each dopant while achieving high luminous efficiency.

Therefore, one aspect of the present invention is to provide a light emitting device having high luminous efficiency in a light emitting device using a plurality of light emitting dopants. Another aspect of the present invention is to provide a light emitting device, a display device, an electronic device, and a lighting device having reduced power consumption by using the above-mentioned light emitting element.

The present invention shall solve any one of the above-mentioned problems.

In the present invention, attention is paid to the Felster mechanism, which is one of the energy transfer mechanisms between molecules, and the peak of the emission spectrum of the molecule giving energy and the absorption spectrum of the molecule receiving energy are set to the fourth power of the wavelength. By applying a combination of molecules that overlaps with the peak having the maximum on the longest wavelength side in the crossed characteristic curve, energy transfer in the Felster mechanism can be efficiently performed. Here, one of the features of the energy transfer is not the general energy transfer from the host to the dopant, but the energy transfer between the dopants. As described above, by applying a combination of dopants so as to increase the energy transfer efficiency between the dopants and designing an element structure for appropriately separating each dopant molecule, the light emitting device according to one aspect of the present invention can be used. Can be obtained.

That is, in one aspect of the present invention, the first phosphorescent compound is longer than the first light emitting layer in which the first phosphorescent compound is dispersed in the first host material and the first phosphorescent compound between the pair of electrodes. The second phosphorescent compound exhibiting wavelength emission comprises a second light emitting layer dispersed in a second host material and is represented by ε (λ) λ ⁴ of the second phosphorescent compound. This is a light emitting element whose maximum wavelength located on the longest wavelength side of the function overlaps with the phosphorescent emission spectrum F (λ) of the first phosphorescent compound. (However, ε (λ) represents the molar extinction coefficient of each phosphorescent compound and is a function of the wavelength λ.)

In addition, another aspect of the present invention comprises a first light emitting layer in which a first phosphorescent compound is dispersed in a first host material between a pair of electrodes, and a first phosphorescent compound. The second phosphorescent compound, which also exhibits long wavelength emission, comprises a second light emitting layer dispersed in a second host material, and is the maximum value of the phosphorescent emission spectrum in the first phosphorescent compound. It is a light emitting element in which a mountain containing a mountain and a mountain containing a maximum value located on the longest wavelength side of the function represented by ε (λ) λ ⁴ of the second phosphorescent compound overlap. (However, ε (λ) represents the molar extinction coefficient of each phosphorescent compound and is a function of the wavelength λ.)

Further, in another aspect of the present invention, in the above configuration, the first light emitting layer further contains the first organic compound, the first host material and the first organic compound form an excited complex, and the first It is a light emitting element in which the light emission of the phosphorescent compound of 1 has a longer wavelength than the light emission of the excited complex.

In addition, another aspect of the present invention is the maximum located on the longest wavelength side of the emission spectrum of the excited complex and the function represented by ε (λ) λ ⁴ of the first phosphorescent compound in the above configuration. It is a light emitting element in which the wavelengths of the values overlap. (However, ε (λ) represents the molar extinction coefficient of each phosphorescent compound.
A function of wavelength λ. )

Further, another aspect of the present invention is the most of the function represented by the peak including the maximum value of the emission spectrum of the excited complex and ε (λ) λ ⁴ of the first phosphorescent compound in the above configuration. It is a light emitting element that overlaps with a mountain containing a maximum value located on the long wavelength side. (However, ε (λ) represents the molar extinction coefficient of each phosphorescent compound and is a function of the wavelength λ.)

Further, in another aspect of the present invention, in the above configuration, the first phosphorescent compound is 500 nm.
The second phosphorescent compound has a phosphorescent peak in the range of to 600 nm, and the second phosphorescent compound is 600 n.
It is a light emitting device having a phosphorescence peak in the range of m to 700 nm.

Further, another aspect of the present invention is a light emitting device in which the recombination region of electrons and holes is the first light emitting layer in the above configuration.

Further, in another aspect of the present invention, in the above configuration, the first light emitting layer is located on the anode side of the second light emitting layer, and at least the second light emitting layer is electron transporting rather than hole transporting property. It is a light emitting element with high properties.

Further, in another aspect of the present invention, in the above configuration, the first light emitting layer is located on the anode side of the second light emitting layer, and both the first host material and the second host material are electron-transported. It is a light emitting element having a property. As the material having electron transportability, a material having higher electron transportability than hole transportability is preferable.

Further, in another aspect of the present invention, in the above configuration, the first light emitting layer is located on the cathode side of the second light emitting layer, and at least the second light emitting layer transports holes rather than electron transport. It is a light emitting element with high properties.

Further, in another aspect of the present invention, in the above configuration, the first light emitting layer is located on the cathode side of the second light emitting layer, and both the first host material and the second host material are holes. It is a light emitting element having transportability. As the material having hole transportability, a material having higher hole transportability than electron transportability is preferable.

Further, another aspect of the present invention is a light emitting element in which the first light emitting layer and the second light emitting layer are laminated in contact with each other in the above configuration.

Further, another aspect of the present invention is a light emitting device, a light emitting display device, an electronic device, and a lighting device provided with a light emitting element having the above configuration.

The light emitting device in the present specification includes an image display device using a light emitting element. Further, the light emitting element has a connector, for example, an anisotropic conductive film, or TCP (Tape C).
Modules with an arrier package) attached, modules with a printed wiring board at the end of TCP, or modules with an IC (integrated circuit) directly mounted on a light emitting element by the COG (Chip On Glass) method are all light emitting devices. It shall include. Further, it shall include a light emitting device used for lighting equipment and the like.

One aspect of the present invention can provide a light emitting device having high luminous efficiency. One aspect of the present invention can provide a light emitting device, a light emitting display device, an electronic device, and a lighting device having reduced power consumption by using the light emitting element.

Conceptual diagram of a light emitting element. Diagram showing energy transfer of light emitting layer The figure explaining Felster movement. Conceptual diagram of an active matrix type light emitting device. Conceptual diagram of a passive matrix type light emitting device. Conceptual diagram of an active matrix type light emitting device. Conceptual diagram of an active matrix type light emitting device. Conceptual diagram of a lighting device. The figure which shows the electronic device. The figure which shows the electronic device. The figure which shows the lighting equipment. The figure which shows the lighting device and the display device. The figure which shows an in-vehicle display device and a lighting device. The figure which shows the electronic device. Luminance-current efficiency characteristics of the light emitting element 1. Voltage-luminance characteristic of light emitting element 1. Luminance of light emitting device 1-external quantum efficiency characteristics. Luminance-power efficiency characteristics of the light emitting element 1. Emission spectrum of the light emitting element 1. The figure explaining the Felster movement of a light emitting element 1. The figure explaining the Felster movement of a light emitting element 1. The figure explaining the Felster movement of a light emitting element 1. PL spectrum of 2mDBTPDBq-II, PCBA1BP and their mixed film. Luminance-current efficiency characteristics of the light emitting element 2. Voltage-luminance characteristic of light emitting element 2. Luminance of light emitting device 2-external quantum efficiency characteristics. Luminance-power efficiency characteristics of the light emitting element 2. Emission spectrum of the light emitting element 2. The figure which shows the reliability test result of a light emitting element 2. Luminance-current efficiency characteristics of the light emitting element 3. Voltage-luminance characteristic of the light emitting element 3. Luminance of light emitting device 3-external quantum efficiency characteristics. Luminance-power efficiency characteristics of the light emitting element 3. Emission spectrum of the light emitting element 3. Luminance-current efficiency characteristics of the light emitting element 4. Voltage-luminance characteristic of the light emitting element 4. Luminance-external quantum efficiency characteristics of the light emitting device 4. Luminance-power efficiency characteristics of the light emitting element 4. Emission spectrum of the light emitting element 4. Luminance-current efficiency characteristics of the light emitting element 5. Voltage-luminance characteristic of the light emitting element 5. Luminance-external quantum efficiency characteristics of the light emitting device 5. Luminance-power efficiency characteristics of the light emitting element 5. Emission spectrum of the light emitting element 5. The figure explaining the Felster movement of a light emitting element 4. The figure explaining the Felster movement of a light emitting element 4. The figure explaining the Felster movement of a light emitting element 5. The figure explaining the Felster movement of a light emitting element 5. The figure explaining the Felster movement of a light emitting element 5.

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 it is easily understood by those skilled in the art that the form and details of the present invention can be variously changed without departing from the spirit and scope of the present invention. Therefore, the present invention is not construed as being limited to the description of the embodiments shown below.

(Embodiment 1)
First, the operating principle of the light emitting device according to one aspect of the present invention will be described. The gist of the present invention is to use a first phosphorescent compound and a second phosphorescent compound that emits light having a longer wavelength than the first phosphorescent compound, and the first phosphorescent compound and the first phosphorescent compound. By efficiently emitting both of the phosphorescent compounds of No. 2, a highly efficient multicolor light emitting element is obtained.

As a general method for obtaining a multicolor light emitting element using a phosphorescent compound, a method of dispersing a plurality of phosphorescent compounds having different emission colors in an appropriate ratio in some host material can be considered. However, in the case of such a method, the phosphorescent compound exhibiting the longest wavelength emission tends to emit light, so that the element structure for obtaining multicolor emission (particularly the concentration of each phosphorescent compound in the host material) ) Is very difficult to design and control.

As another method for obtaining a multicolor light emitting element, there is a so-called tandem structure in which light emitting elements having different light emitting colors are laminated in series. For example, if a blue light emitting element, a green light emitting element, and a red light emitting element are laminated in series and emitted at the same time, multicolored light (white light in this case) can be easily obtained. As for the element structure, it is sufficient to optimize each of the blue, green, and red elements, so the design and design
Control is relatively easy. However, since the three elements are laminated, the number of layers increases and the production becomes complicated. Further, if a problem occurs in the electrical contact at the connection portion (so-called intermediate layer) of each element, the drive voltage may increase, that is, power loss may occur.

On the other hand, the light emitting element of one aspect of the present invention is composed of a first light emitting layer in which a first phosphorescent compound is dispersed in a first host material and a first phosphorescent compound between a pair of electrodes. Is also a light emitting element in which a second light emitting layer in which a second phosphorescent compound exhibiting long wavelength light emission is dispersed in a second host material is laminated. At this time, unlike the tandem structure, the first light emitting layer and the second light emitting layer may be provided in contact with each other.

FIG. 1 schematically shows the element structure of the light emitting device of one aspect of the present invention described above. FIG. 1C shows a first electrode 101, a second electrode 102, and an EL layer 103. The EL layer 103 is provided with at least a light emitting layer 113, and other layers may be appropriately provided.
FIG. 1C tentatively shows a configuration in which the hole injection layer 111, the hole transport layer 112, the electron transport layer 114, and the electron injection layer 115 are provided. It is assumed that the first electrode 101 functions as an anode and the second electrode 102 functions as a cathode.

Further, FIGS. 1A and 1B are enlarged views showing the light emitting layer 113 in the light emitting element. 1A and 1B show a first light emitting layer 113a, a second light emitting layer 113b, and the second light emitting layer 113a.
The combined light emitting layer 113, the first phosphorescent compound 113Da, the second phosphorescent compound 1
13Db, a first host material 113Ha, and a second host material 113Hb are shown.
Note that FIG. 1B is a schematic diagram in the case where the first light emitting layer 113a further contains the first organic compound 113A. In either case, each phosphorescent compound (first and second)
Phosphorescent compounds) are dispersed in the host material, so that each phosphorescent compound is isolated from each other by each host material. The first and second host materials may be the same or different. Further, either of the first light emitting layer 113a and the second light emitting layer 113b may be on the anode side or the cathode side.

In this case, electron exchange interaction (so-called Dexter mechanism) between each phosphorescent compound.
Energy transfer due to is suppressed. That is, after the first phosphorescent compound 113Da is excited, the excitation energy thereof is transferred to the second phosphorescent compound 113Db by the Dexter mechanism.
It is possible to prevent the phenomenon of moving to. Therefore, it is possible to suppress the phenomenon that the second phosphorescent compound 113Db, which emits light having the longest wavelength, mainly emits light. The second
When excitons are directly generated in the light emitting layer 113b of the above, the second phosphorescent compound 113Db mainly emits light, so that the recombination region of the carrier is set in the first light emitting layer 113a (that is, the first light emitting layer 113a). It is preferable to mainly excite the phosphorescent compound 113Da).

However, if the energy transfer from the first phosphorescent compound 113Da is completely suppressed, the light emission of the second phosphorescent compound 113Db cannot be obtained this time. Therefore, in one aspect of the present invention, the excitation energy of the first phosphorescent compound 113Da is partially the second.
The device is designed so as to move to the phosphorescent compound 113Db. Energy transfer between such isolated molecules is possible by utilizing a dipole-dipole interaction (Felster mechanism).

Here, the Felster mechanism will be described. In the following, the molecule that gives the excitation energy is referred to as an energy donor, and the molecule that receives the excitation energy is referred to as an energy acceptor. That is, in one aspect of the present invention, both the energy donor and the energy acceptor are phosphorescent compounds and are isolated from each other by a host material.

The Felster mechanism does not require direct intramolecular contact for energy transfer. Energy transfer occurs through the resonance phenomenon of dipole oscillations between energy donors and energy acceptors. Due to the resonance phenomenon of bipolar vibration, the energy donor transfers energy to the energy acceptor, the excited energy donor becomes the ground state, and the ground state energy acceptor becomes the excited state. The rate constant k _F of energy transfer by the Felster mechanism is shown in equation (1).

In equation (1), ν represents the frequency, and F (ν) is from the standardized emission spectrum of the energy donor (fluorescence spectrum when discussing energy transfer from the single-term excited state, triple-term excited state). Represents the phosphorescent spectrum when discussing the energy transfer of
ν) represents the molar extinction coefficient of the energy acceptor, N represents the Avogadro's number, and n
Is the refractive index of the medium, R is the intermolecular distance between the energy donor and the energy acceptor, τ is the lifetime of the actually measured excited state (fluorescence lifetime and phosphorescent lifetime), and c is the light velocity. Represents φ, and φ represents the emission quantum yield (fluorescence quantum yield when discussing energy transfer from the single-term excited state, phosphorous quantum yield when discussing energy transfer from the triple ^- term excited state). Is a coefficient (0-4) representing the orientation of the transition dipole moment between the energy donor and the energy acceptor. In the case of random orientation, K ² = 2/3.

As can be seen from the equation (1), the conditions for energy transfer (Felster transfer) by the Felster mechanism are 1. 2. The energy donor and energy acceptor should not be too far apart (related to distance R). 2. The energy donor emits light (related to the emission quantum yield φ). The fact that the emission spectrum of the energy donor and the absorption spectrum of the energy acceptor have an overlap (related to the integration term) can be mentioned.

Here, as described with reference to FIG. 1, each phosphorescent compound (first and second phosphorescent compounds).
Is dispersed in each host material, and each phosphorescent compound is isolated from each other by each host material, so that the distance R has a distance of at least one molecule (1 nm or more).
Therefore, not all of the excitation energy generated by the first phosphorescent compound is transferred to the second phosphorescent compound by the Felster mechanism. On the other hand, R is 1
Felster movement is possible within the range of 0 nm to 20 nm. In order to secure a distance R of at least one molecule or more between the first and second phosphorescent compounds, it is preferable that the volume of each phosphorescent compound dispersed in the host material is constant or less. The concentration of each phosphorescent compound corresponding to this in the light emitting layer is 10 wt% or less. Since it is difficult to obtain good characteristics even if the concentration of the phosphorescent compound is too low, the concentration of the phosphorescent compound in the present embodiment is preferably 0.1 wt% or more and 10 wt% or less. In particular, it is more preferable that the first phosphorescent compound is contained in the first light emitting layer 113a at a concentration of 0.1 wt% or more and 5 wt% or less.

Each phosphorescent element in the light emitting element of one aspect of the present invention using the first phosphorescent compound 113Da and the second phosphorescent compound 113Db exhibiting light emission at a longer wavelength than the first phosphorescent compound. A schematic diagram of Felster transfer between compounds is shown in FIG. FIG. 2 shows a configuration in which the first light emitting layer 113a and the second light emitting layer 113b are laminated between the electrodes 10 and 11. One of the electrode 10 and the electrode 11 functions as an anode, and the other is an electrode that functions as a cathode. As shown in FIG. 2 (A), the singlet excited state (S _a ) generated by the first phosphorescent compound 113 Da is first converted into a triplet excited state (T _a ) by intersystem crossing.
That is, the excitons in the first light emitting layer _113a are basically concentrated in Ta.

Next, part of the energy of the excitons in the Ta state is converted into light emission as it is, but by using the Felster mechanism, part of it is in the triplet excited state of the second phosphorescent compound _113Db . You can move to (T _b ). This is because the first phosphorescent compound 113Da is luminescent (the phosphorescence quantum yield φ is high) and the second phosphorescent compound 113Db has an electron transition from the singlet ground state to the triplet excited state. This is due to the fact that it has direct absorption corresponding to (there is an absorption spectrum in the triplet excited state). If these conditions are met, T
Triplet-triplet _Felster transfer from _a to Tb is possible.

The singlet excited state (S _b ) of the second phosphorescent compound 113Db often has higher energy than the triplet excited state (Ta) of the first phosphorescent compound _113Da , and thus is described above. In many cases, it does not contribute much to energy transfer. Therefore, it is omitted here.
Of course, when the singlet excited state (S _b ) of the second phosphorescent compound 113Db has _a lower energy than the triplet excited state (Ta) of the first phosphorescent compound 113Da, energy transfer occurs in the same manner. sell. In this case, the singlet excited state of the second phosphorescent compound 113Db (
The energy transferred to S _b ) is transferred to the triplet excited state (T _b ) of the second phosphorescent compound 113Db via the intersystem crossing and is involved in light emission.

In order to efficiently generate the above-mentioned Felster transfer between phosphorescent compounds which are dopants and to design the host material so as not to transfer energy, the first and second host materials are first. It is preferable that the phosphorescent compound 113Da does not have an absorption spectrum in the light emitting region. In this way, by allowing energy transfer directly between the dopants without going through the host material (specifically, the second host material), the generation of extra energy transfer paths is suppressed and the luminous efficiency is high. It is a preferable configuration because it can be tied together.

Further, the first host material preferably has a triplet excitation energy higher than that of the first phosphorescent compound so as not to quench the first phosphorescent compound.

As described above, the basic concept of one aspect of the present invention is to first isolate the first and second phosphorescent compounds using a host material and a laminated structure, while exhibiting short wavelength emission. The element structure is to mainly excite the phosphorescent compound of. In such an element structure, Felster-type energy transfer occurs in part within a certain distance (up to 20 nm), so that the excitation energy of the first phosphorescent compound is partially second. It is possible to move to the phosphorescent compound and obtain light emission from each of the first and second phosphorescent compounds.

However, what is more important here in one aspect of the present invention is the selection of materials and the device structure in consideration of the energy transfer.

First, in order to generate Felster movement, the emission quantum yield φ on the energy donor side needs to be high, but in one aspect of the present invention, the phosphorescent compound (specifically, the phosphorescence quantum yield is Since 0.1 or more luminescent compounds) are used, no problem occurs. The important point is the formula (1)
) Is increased, that is, the emission spectrum F (ν) of the energy donor and the molar extinction coefficient ε (ν) of the energy acceptor are successfully overlapped.

In general, the emission spectra F (ν) of the energy donors may be overlapped in the wavelength region where the molar absorption coefficient ε (ν) of the energy acceptor is large (that is, the product of F (ν) ε (ν) should be increased. It is considered good). However, this is not always true in the Felster mechanism. This is because the integral term of Eq. (1) is inversely proportional to the fourth power of the frequency ν.
This is because there is a wavelength dependence.

In order to make it easier to understand, first, the equation (1) is modified. Let λ be the wavelength of light, then ν = c
Since / λ, the equation (1) can be rewritten as the following equation (2).

That is, it can be seen that the integral term becomes larger as the wavelength λ is larger. In short, it means that energy transfer is more likely to occur on the longer wavelength side. That is, the molar extinction coefficient ε (λ)
It is not a simple matter that F (λ) overlaps in a wavelength region where ε (λ) λ ⁴ is large, but F (λ) must overlap in a region where ε (λ) λ 4 is large.

Therefore, as the second phosphorescent compound 113Db in the light emitting element of one aspect of the present invention, in order to increase the energy transfer efficiency from the first phosphorescent compound 113Da, the light emission of the first phosphorescent compound 113Da. The peak of the spectrum where the maximum value of the spectrum exists and the second
The phosphorescent compound of 113Db is used so that the peaks having the maximum value located on the longest wavelength side of the function represented by ε (λ) λ ⁴ overlap are overlapped.

The wavelength of the maximum value located on the longest wavelength side of the function represented by ε (λ) λ ⁴ of the second phosphorescent compound is the phosphorescence emission spectrum F (λ) of the first phosphorescent compound. It is preferable that it overlaps with. Further, the wavelength range having half the intensity of the maximum value in the mountain where the maximum value of the emission spectrum of the first phosphorescent compound 113Da exists, and ε (λ) λ ⁴ of the second phosphorescent compound. It is more preferable that there is an overlap in the wavelength range having half the intensity of the maximum value in the mountain where the maximum value of the function represented by is present, because the overlap between the spectra becomes large.

The light emitting device having the above configuration can be a light emitting device having high luminous efficiency and capable of obtaining light emission from each phosphorescent compound in a well-balanced manner.

In order to deepen the understanding of the constitution of such a phosphorescent compound, a specific example will be described below. Here, as the first phosphorescent compound 113Da, the following compound (1) (bis [
2- (6-tert-butyl-4-pyrimidinyl-κN3) phenyl-κC] (2,4-
Pentane Dionato-κ ² O, O') Iridium (III) (abbreviation: Ir (tBuppm))
₂ (acac))) has a second emission that exhibits a longer wavelength than that of the first phosphorescent compound 113Da.
As the phosphorescent compound 113Db, the following compounds (2) (bis (2,3,5-triphenylpyrazinato) (dipyvaloylmethanato) iridium (III) (abbreviation: Ir (tppr))
) ₂ (dpm))) will be described as an example.

FIG. 3A shows the molar extinction coefficient ε (λ) of the compound (2), which is the second phosphorescent compound, and ε.
(Λ) λ ⁴ and so on. The molar extinction coefficient ε (λ) decreases toward the long wavelength side, but ε (λ) λ ⁴ has a maximum value near 550 nm (corresponding to the triple term MLCT absorption band of compound (2)). is doing. As can be seen from this example, due to the influence of the term λ ⁴ , the second phosphorescent compound ε (λ) λ ⁴ has a maximum value in the absorption band (triplet MLCT absorption band) located on the longest wavelength side. Has.

On the other hand, FIG. 3 (b) shows the photoluminescence (PL) spectrum F (λ) of the compound (1).
And ε (λ) λ ⁴ of the compound (2). Compound (1) is the first phosphorescent compound and exhibits green emission having an emission peak near 545 nm. The PL spectrum F (λ) of the first phosphorescent compound has a large overlap with ε (λ) λ ⁴ near the maximum value of ε (λ) λ ⁴ of the second phosphorescent compound. Therefore, energy transfer by the Felster mechanism occurs from the first phosphorescent compound to the second phosphorescent compound. In this case, since the maximum value corresponds to the triplet MLCT absorption band, it is a triplet-triplet Felster-type energy transfer _{(Ta-T b energy} transfer in FIG. 2). At this time, the emission peak wavelength of the PL spectrum F (λ) of the first phosphorescent compound and ε (ε) of the second phosphorescent compound.
When the difference in wavelength of the maximum value of λ) λ ⁴ is 0.2 eV or less, energy transfer is efficiently performed, which is a preferable configuration. The emission peak wavelength of the PL spectrum F (λ) of the compound (1) is 546 nm, and the wavelength of the maximum value of ε (λ) λ ⁴ of the compound (2) is 543 nm, and the difference corresponds to 0.01 eV at 3 nm. Therefore, it can be seen that the energy transfer between the compound (1) and the compound (2) is very efficient.

From the above, the second phosphorescent compound is directly absorbed (for example, triplet ML) corresponding to the electronic transition from the singlet ground state to the triplet excited state on the longest wavelength side of the absorption spectrum.
It is preferable to have CT absorption). With such a configuration, triplet-triplet energy transfer as shown in FIG. 2 can be efficiently generated.

Further, when the first light emitting layer 113a is located on the anode side in order to obtain the above-mentioned recombination region, it is preferable that at least the second light emitting layer 113b is electron transportable, and the first light emitting layer 1
Both 13a and the second light emitting layer 113b may be electron transportable. When the first light emitting layer 113a is located on the cathode side, at least the second light emitting layer 113b is preferably hole-transporting, and both the first light emitting layer 113a and the second light emitting layer 113b are positive. It may be hole transportable.

Here, in the first light emitting layer 113a, a mountain in which a maximum value of the photoluminescence (PL) spectrum F (λ) of the first host material 113Ha is present and ε (ε) of the first phosphorescent compound are further present. λ) It is preferable that the overlap of the peaks having the maximum value located on the longest wavelength side of the function represented by λ ⁴ is large.

However, usually the photoluminescence (PL) spectrum F (λ) of the host material
Ε (λ) λ of the guest material (first phosphorescent compound 113Da) and the mountain where the maximum value of
It is difficult to overlap with the mountain where the maximum value located on the longest wavelength side of the function represented by ⁴ exists. This is because the photoluminescence (PL) of the host material is usually fluorescence emission, and the fluorescence emission is from an energy level higher than that of phosphorescence emission, so that the fluorescence spectrum is absorbed on the longest wavelength side of the guest material. This is because the triple-term excitation energy level of the host material at a wavelength close to the spectrum (triple-term excited state of the guest material) is likely to be lower than the triple-term excitation energy level of the guest material. If the triplet excitation energy level of the host material is lower than the triplet excitation energy level of the guest material, the triplet excitation energy of the guest material is transferred to the host material, resulting in a decrease in emission efficiency.

Therefore, in the present embodiment, the first light emitting layer 113a is further the first organic compound 113.
The first host material 113Ha and the first organic compound 113A containing A are the excitation complex 11.
It is preferable that the combination forms 3Ec (also referred to as exciplex) (FIGS. 1 (b) and 2 (B)). In FIG. 2B, 10 and 11 are electrodes, and one of the electrodes 10 and 11 functions as an anode and the other functions as a cathode. In the figure, the excitation complex 113E
The singlet excited state of c is represented by Se, the triplet excited state is represented by Te, and the first phosphorescent compound 11
The singlet excited state of 3Da is represented by Sa, the triplet excited state is represented by Ta, the singlet excited state of the second phosphorescent compound 113Db is represented by Sb, and the triplet excited state is represented by Tb.

In this case, when the first organic compound 113A and the first host material 113Ha obtain energy by recombination of electrons and holes during the recombination of carriers (electrons and holes) in the first light emitting layer 113a, The excitation complex 113Ec is formed. The fluorescence emission from the excited complex 113Ec is a emission having a spectrum on the longer wavelength side than the fluorescence spectrum of the first organic compound 113A alone and the first host material 113Ha alone, but the singlet excited state Se of the excited complex 113Ec. And the triplet excited state Te has the feature that the energies are very close. Therefore, the PL spectrum F (λ), which is the emission from the singlet excited state of the excited complex 113Ec.
Ε (λ) λ of the guest material (first phosphorescent compound 113Da) and the mountain where the maximum value of
By superimposing the mountain (corresponding to the absorption spectrum of the triple-term excited state Ta of the guest material) where the maximum value located on the longest wavelength side of the function represented by ⁴ exists, the energy transfer from Se to Ta and Both the energy transfer from Te to Ta can be maximized. At this time, the emission peak wavelength of the excited complex 113Ec and the guest material (first phosphorescent compound 113)
When the difference in wavelength of the maximum value of ε (λ) λ ⁴ of Da) is 0.2 eV or less, energy transfer is efficiently performed, which is a preferable configuration. Further, it is preferable to keep the triplet excitation energy level of the first organic compound 113A and the first host material 113Ha higher than the triplet excitation energy level of the first phosphorescent compound 113Da.

As described above, the energy transferred to the first phosphorescent compound 113Da is partially transferred to the second phosphorescent compound 113Db, and the energy is partially transferred to the first phosphorescent compound 113Da.
And the second phosphorescent compound 113Db both emit light efficiently.

From the triplet excited state (Te) of the excited complex 113Ec, the first phosphorescent compound 113D
Energy transfer to a occurs efficiently by the Dexter mechanism. Singlet excited state (Se
) Is efficiently transferred by the Felster mechanism having the above configuration, so that total efficient energy transfer is realized.

The first organic compound 113A and the first host material 113Ha may be any combination that produces an excited complex, but a compound that easily receives electrons (electron trapping compound) and a compound that easily receives electrons are used.
It is preferable to combine it with a compound that easily receives holes (hole trapping compound).

Compounds that easily receive electrons include bis (10-hydroxybenzo [h] quinolinato) beryllium (II) (abbreviation: BeBq ₂ ) and bis (2-methyl-8-quinolinolato) (
4-Phenylphenorato) Aluminum (III) (abbreviation: BAlq), Bis (8-quinolinolato) Zinc (II) (abbreviation: Znq), Bis [2- (2-benzoxazolyl) phenolato] Zinc (II) Metal complexes such as (abbreviation: ZnPBO), bis [2- (2-benzothiazolyl) phenolato] zinc (II) (abbreviation: ZnBTZ), 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole (abbreviation: P)
BD), 3- (4-biphenylyl) -4-phenyl-5- (4-tert-butylphenyl) -1,2,4-triazole (abbreviation: TAZ), 1,3-bis [5- (p-) tert
-Butylphenyl) -1,3,4-oxadiazole-2-yl] benzene (abbreviation: OX)
D-7), 9- [4- (5-phenyl-1,3,4-oxadiazole-2-yl) phenyl] -9H-carbazole (abbreviation: CO11), 2,2', 2''- (1,3,5-Benzenetriyl) Tris (1-phenyl-1H-benzimidazole) (abbreviation: TPBI)
), 2- [3- (Dibenzothiophen-4-yl) phenyl] -1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II) and other heterocyclic compounds having a polyazole skeleton, and 2- [3-( Dibenzothiophene-4-yl) Phenyl] Dibenzo [f, h
] Quinoxaline (abbreviation: 2mDBTPDBq-II), 2- [3'-(dibenzothiophen-4-yl) biphenyl-3-yl] dibenzo [f, h] quinoxaline (abbreviation: 2mD)
BTBPDBq-II), 2- [3'-(9H-carbazole-9-yl) biphenyl-
3-Il] dibenzo [f, h] quinoxaline (abbreviation: 2mCzBPDBq), 4,6-bis [3- (phenanthrene-9-yl) phenyl] pyrimidine (abbreviation: 4,6mPnP2)
Pm), 4,6-bis [3- (4-dibenzothienyl) phenyl] pyrimidine (abbreviation: 4)
, 6mDBTP2Pm-II) and other heterocyclic compounds with a diazine skeleton, and 3,5-bis [3- (9H-carbazole-9-yl) phenyl] pyridine (abbreviation: 35DCzPP).
y), 1,3,5-tri [3- (3-pyridyl) -phenyl] benzene (abbreviation: TmPy)
Examples thereof include heterocyclic compounds having a pyridine skeleton such as PB). Among the above, the heterocyclic compound having a diazine skeleton and the 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 has high electron transport properties and contributes to a reduction in driving voltage.

Compounds that easily receive holes include 4,4'-bis [N- (1-naphthyl) -N-.
Phenylamino] Biphenyl (abbreviation: NPB), N, N'-bis (3-methylphenyl)
-N, N'-diphenyl- [1,1'-biphenyl] -4,4'-diamine (abbreviation: TP)
D), 4,4'-bis [N- (spiro-9,9'-bifluorene-2-yl) -N-phenylamino] biphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenyl) Fluorene-9-yl) Triphenylamine (abbreviation: BPAFLP), 4-Phenyl-3'-
(9-Phenylfluorene-9-yl) Triphenylamine (abbreviation: mBPAFLP),
4-Phenyl-4'-(9-Phenyl-9H-Carbazole-3-yl) Triphenylamine (abbreviation: PCBA1BP), 4,4'-Diphenyl-4''-(9-Phenyl-9H)
-Carbazole-3-yl) 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), 9,9
-Dimethyl-N-Phenyl-N- [4- (9-Phenyl-9H-Carbazole-3-yl) phenyl] Fluorene-2-amine (abbreviation: PCBAF), N-Phenyl-N- [4-
(9-Phenyl-9H-carbazole-3-yl) phenyl] Spiro-9,9'-bifluoren-2-amine (abbreviation: PCBASF) and other compounds with an aromatic amine skeleton,
1,3-bis (N-carbazolyl) benzene (abbreviation: mCP), 4,4'-di (N-carbazolyl) biphenyl (abbreviation: CBP), 3,6-bis (3,5-diphenylphenyl)
-9-Phenylcarbazole (abbreviation: CzTP), 3,3'-bis (9-Phenyl-9H)
-Compounds with a carbazole skeleton such as carbazole (abbreviation: PCCP) and 4,4
', 4''- (benzene-1,3,5-triyl) tri (dibenzothiophene) (abbreviation:
DBT3P-II), 2,8-diphenyl-4- [4- (9-phenyl-9H-fluorene-9-yl) phenyl] dibenzothiophene (abbreviation: DBTFLP-III), 4- [
Compounds having a thiophene skeleton such as 4- (9-phenyl-9H-fluorene-9-yl) phenyl] -6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and 4,
4', 4''-(benzene-1,3,5-triyl) tri (dibenzofuran) (abbreviation: D)
Examples thereof include compounds having a furan skeleton such as BF3P-II), 4- {3- [3- (9-phenyl-9H-fluorene-9-yl) phenyl] phenyl} dibenzofuran (abbreviation: mmDBFFLBi-II). Among the above-mentioned compounds, the compound having an aromatic amine skeleton and the compound having a carbazole skeleton are preferable because they have good reliability, high hole transportability, and contribute to reduction of driving voltage.

The first organic compound 113A and the first host material 113Ha are combinations capable of forming an excited complex without being limited to these, and are photoluminescence (PL) of the excited complex.
) The peak where the maximum value of the spectrum F (λ) exists and the peak where the maximum value located on the longest wavelength side of the function represented by ε (λ) λ ⁴ of the first phosphorescent compound exists. It suffices if the peak of the emission spectrum of the overlapping excitation complex has a longer wavelength than the peak of the emission spectrum of the first phosphorescent compound 113Da.

When the first organic compound 113A and the first host material 113Ha are composed of a compound that easily receives electrons and a compound that easily receives holes, the carrier balance can be controlled by the mixing ratio thereof. Specifically, the range of the first organic compound 113A and the first host material 113Ha = 1: 9 to 9: 1 is preferable.

Here, in this configuration, the peak in which the maximum value of the photoluminescence (PL) spectrum F (λ) of the excited complex exists and the function represented by ε (λ) λ ⁴ of the first phosphorescent compound are the most. First host material 1 that constitutes an excited complex in which peaks having maximum values located on the long wavelength side overlap.
13Ha and the first organic compound 113A are selected. The larger the overlap of the mountains, the better.

The wavelength of the maximum value located on the longest wavelength side of the function represented by ε (λ) λ ⁴ of the first phosphorescent compound overlaps with the photoluminescence (PL) spectrum F (λ) of the excited complex. Is preferable. In addition, the photoluminescence (PL) spectrum F (λ) of the excited complex
In the mountain where the maximum value of) exists, in the wavelength range having half the intensity of the above maximum value, and in the mountain where the maximum value of the function represented by ε (λ) λ ⁴ of the first phosphorescent compound exists. It is more preferable that there is an overlap in the wavelength range having half the intensity of the maximum value because the overlap between the spectra becomes large.

In this configuration, energy can be efficiently transferred from the excited complex composed of the first host material 113Ha and the first organic compound 113A to the first phosphorescent compound 113Da, so that the energy transfer efficiency can be further improved. Since it can be increased, it is possible to realize a light emitting element having a higher external quantum efficiency.

(Embodiment 2)
In this embodiment, an example of the detailed structure of the light emitting device described in the first embodiment will be described below with reference to FIG.

The light emitting element in the present embodiment has an EL layer composed of a plurality of layers between a pair of electrodes.
In the present embodiment, the light emitting element is composed of a first electrode 101, a second electrode 102, and an EL layer 103 provided between the first electrode 101 and the second electrode 102. There is.
In this embodiment, the first electrode 101 functions as an anode and the second electrode 102 functions as a cathode, which will be described below. That is, the first electrode 101 is the second electrode 10.
When a voltage is applied to the first electrode 101 and the second electrode 102 so that the potential is higher than that of 2, light emission is obtained.

Since the first electrode 101 functions as an anode, it has a large work function (specifically, 4.0e).
V or more) It is preferable to form using a metal, an alloy, a conductive compound, a mixture thereof, or the like. Specifically, for example, indium oxide-tin oxide (ITO: Indium T)
in Oxide), indium oxide containing silicon or silicon oxide-tin oxide,
Indium oxide-Indium oxide containing zinc oxide, tungsten oxide and zinc oxide (
IWZO) and the like. These conductive metal oxide films are usually formed by a sputtering method, but may be produced by applying a sol-gel method or the like. As an example of the production method, indium oxide-zinc oxide may be formed by a sputtering method using a target in which 1 to 20 wt% zinc oxide is added to indium oxide. Indium oxide (IWZO) containing tungsten oxide and zinc oxide is formed by a sputtering method using a target containing 0.5 to 5 wt% of tungsten oxide and 0.1 to 1 wt% of zinc oxide with respect to indium oxide. You can also do it. In addition, gold (Au) and platinum (
Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo)
, Iron (Fe), Cobalt (Co), Copper (Cu), Palladium (Pd), Nitride of metallic material (eg, Titanium Nitride) and the like. Graphene can also be used. By using the composite material described later for the layer in contact with the first electrode 101 in the EL layer 103, the electrode material can be selected regardless of the work function.

The laminated structure of the EL layer 103 is not particularly limited as long as the light emitting layer 113 has a structure as shown in the first embodiment. For example, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, a carrier block layer, an intermediate layer, and the like can be appropriately combined. In the present embodiment, the EL layer 103 includes a hole injection layer 111, a hole transport layer 112, a light emitting layer 113, an electron transport layer 114, and an electron injection layer 115, which are sequentially laminated on the first electrode 101.
The configuration having the above will be described. The materials constituting each layer are specifically shown below.

The hole injection layer 111 is a layer containing a substance having a high hole injection property. Molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, manganese oxide and the like can be used. In addition, phthalocyanine (abbreviation: H ₂ Pc) and copper phthalocyanine (CuPC)
Phtalocyanin compounds such as 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) and other aromatic amine compounds, or poly (ethylenedioxythiophene) / Poly (styrene sulfonic acid) (PEDOT / PSS)
The hole injection layer 111 can also be formed by using a polymer such as).

Further, as the hole injection layer 111, a composite material containing an acceptor substance in a hole transporting substance can be used. By using a hole-transporting substance containing an acceptor-like substance, it is possible to select a material for forming the electrode regardless of the work function of the electrode. That is, not only a material having a large work function but also a material having a small work function can be used as the first electrode 101. Acceptor substances include 7, 7, 8
, 8-Tetracyano-2,3,5,6 _- Tetrafluoroquinodimethane (abbreviation: F4-TC)
NQ), chloranil and the like can be mentioned. Also, transition metal oxides can be mentioned. Further, oxides of metals belonging to Group 4 to Group 8 in the Periodic Table of the Elements can be mentioned. Specifically, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, and renium oxide are preferable because they have high electron acceptability. Among them, molybdenum oxide is particularly preferable because it is stable in the atmosphere, has low hygroscopicity, and is easy to handle.

As the hole-transporting substance used in the composite material, various organic compounds such as an aromatic amine compound, a carbazole derivative, an aromatic hydrocarbon, and a polymer compound (oligomer, dendrimer, polymer, etc.) can be used. The organic compound used in the composite material is preferably an organic compound having a high hole transport property. Specifically, it is preferably a substance having a hole mobility of 10 to ⁶ cm ² / Vs or more. In the following, organic compounds that can be used as hole-transporting substances in composite materials are specifically listed.

For example, examples of the aromatic amine compound include N, N'-di (p-tolyl) -N, N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4,4'-bis [N- (4- (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] benzene (abbreviation: DPA3B) and the like can be mentioned.

Specific examples of the carbazole derivative that can be used in the composite material include 3-[N-.
(9-Phenylcarbazole-3-yl) -9-phenylamino] -9-Phenylcarbazole (abbreviation: PCzPCA1), 3,6-bis [N- (9-phenylcarbazole-3)
-Il) -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.

In addition, other carbazole derivatives that can be used in composite materials include 4,4'-.
Di (N-carbazolyl) biphenyl (abbreviation: CBP), 1,3,5-tris [4- (N-)
Carbazole) 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 and the like can be used.

Examples of aromatic hydrocarbons that can be used in composite materials include 2-tert.
-Butyl-9,10-di (2-naphthyl) anthracene (abbreviation: t-BuDNA), 2-
tert-Butyl-9,10-di (1-naphthyl) anthracene, 9,10-bis (3,
5-Diphenylphenyl) anthracene (abbreviation: DPPA), 2-tert-butyl-9
, 10-bis (4-phenylphenyl) anthracene (abbreviation: t-BuDBA), 9,1
0-di (2-naphthyl) anthracene (abbreviation: DNA), 9,10-diphenylanthracene (abbreviation: DPAnth), 2-tert-butylanthracene (abbreviation: t-BuAn)
th), 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, 10,1
0'-Diphenyl-9,9'-bianthril, 10,10'-bis (2-phenylphenyl) -9,9'-bianthril, 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 can be mentioned. In addition, pentacene, coronene and the like can also be used. Thus, ^1x10-6
It is more preferable to use an aromatic hydrocarbon having a hole mobility of cm ² / Vs or more and having 14 to 42 carbon atoms.

The aromatic hydrocarbon that can be used in the composite material may have a vinyl skeleton. Examples of aromatic hydrocarbons having a vinyl group include 4,4'-bis (2,2-).
Diphenylvinyl) Biphenyl (abbreviation: DPVBi), 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] (
Polymer compounds such as poly [N, N'-bis (4-butylphenyl) -N, N'-bis (phenyl) benzidine] (abbreviation: Poly-TPD) can also be used.

By forming the hole injection layer, the hole injection property becomes good, and it becomes possible to obtain a light emitting element having a small drive voltage.

The hole transport layer 112 is a layer containing a hole transporting substance. As a hole-transporting substance,
For example, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (abbreviation: NPB) and N, N'-bis (3-methylphenyl) -N, N'-diphenyl- [ 1,
1'-biphenyl] -4,4'-diamine (abbreviation: TPD), 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'-
Aromatic amine compounds such as (9-phenylfluorene-9-yl) triphenylamine (abbreviation: BPAFLP) can be used. The substances described here have high hole transport properties and mainly have hole mobilities of ^10-6 cm ² / Vs or more. Further, the organic compound mentioned as the hole transporting substance in the above-mentioned composite material can also be used for the hole transport layer 112. Further, polymer compounds such as poly (N-vinylcarbazole) (abbreviation: PVK) and poly (4-vinyltriphenylamine) (abbreviation: PVTPA) can also be used. The layer containing the hole-transporting substance 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 light emitting layer 113 is a layer containing a first phosphorescent compound and a second phosphorescent compound. Since the light emitting layer 113 has the configuration as described in the first embodiment, the light emitting element in the present embodiment can be a light emitting element having very good luminous efficiency. Light emitting layer 113
For the main configuration of the above, refer to the description of the first embodiment.

In the light emitting layer 113, the material that can be used as the first phosphorescent compound and the second phosphorescent compound is not particularly limited as long as it is a combination having the relationship as described in the first embodiment. There is no. Examples of the first phosphorescent compound and the second phosphorescent compound include the following.

Tris {2- [5- (2-methylphenyl) -4- (2,6-dimethylphenyl) -4H
-1,2,4-triazole-3-yl-κN ² ] 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-Triazolate] Iridium (III) (abbreviation: Ir (iPrptz-3b) ₃ ) and other organic metal iridium complexes with a 4H-triazole skeleton, and tris [3-methyl-1- (2-methylphenyl)-. 5-Phenyl-1H-1,2,4-triazolat] Iridium (III) (abbreviation: Ir (Mptz1-mp) ₃ ), Tris (1-methyl-5-phenyl-3-propyl-1H-1,2, 4-Triazolate) Iridium (III) (abbreviation: Ir (Prptz1-Me) ₃ ) and other organic metal iridium complexes with a 1H-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 imidazole skeleton Organic metal 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' ] iridium (
III) Examples thereof include an organometallic iridium complex having a phenylpyridine derivative having an electron-withdrawing group such as acetylacetonate (abbreviation: FIracac) as a ligand. These are compounds that exhibit blue phosphorescence emission and have emission peaks from 440 nm to 520 nm. Among the above, organometallic iridium complexes having a polyazole skeleton such as 4H-triazole, 1H-triazole, and imidazole have high hole trapping properties. Therefore, these compounds are used as the first phosphorescent compound in the light emitting element of one aspect of the present invention, the first light emitting layer is provided on the cathode side of the second light emitting layer, and the second light emitting layer. When the layer is hole-transporting (specifically, when the second host material is a hole-transporting material), it becomes easy to control the recombination region of the carrier in the first light emitting layer. Therefore, it is preferable.
The organometallic iridium complex having a 4H-triazole skeleton is particularly preferable because it is excellent in reliability and luminous efficiency.

In addition, Tris (4-methyl-6-phenylpyrimidinat) iridium (III) (abbreviation: abbreviation:
Ir (mppm) ₃ ), Tris (4-t-butyl-6-phenylpyrimidinat) Iridium (III) (abbreviation: Ir (tBuppm) ₃ ), (Acetylacetonato) bis (6-methyl-4-phenyl) Pyrimidineat) Iridium (III) (abbreviation: Ir (mppm) ₂ (
acac)), (acetylacetonato) bis (6-tert-butyl-4-phenylpyrimidinat) iridium (III) (abbreviation: Ir (tBuppm) ₂ (acac)), (acetylacetonato) bis [6- (2-Norbornyl) -4-phenylpyrimidinat] Iridium (III) (abbreviation: Ir (nbppm) ₂ (acac)), (acetylacetonato) bis [5-methyl-6- (2-methylphenyl)- 4-Phenylpyrimidinate] Iridium (III) (abbreviation: Ir (mpmppm) ₂ (acac)), (acetylacetonato) bis (4,6-diphenylpyrimidinato) iridium (III) (abbreviation: Ir (dpp)
m) Organometallic iridium complexes with a pyrimidine skeleton such as ₂ (acac)) and (acetylacetonato) bis (3,5-dimethyl-2-phenylpyrazinato) iridium (I)
II) (abbreviation: Ir (mppr-Me) ₂ (acac)), (acetylacetonato) bis (5-isopropyl-3-methyl-2-phenylpyrazinato) iridium (III) (abbreviation: Ir (mppr-) Organic metal iridium complexes with a pyrazine skeleton such as iPr) ₂ (acac)) and tris (2-phenylpyridinato-N, C ^2' ) iridium (III).
) (Abbreviation: Ir (ppy) ₃ ), bis (2-phenylpyridinato-N, C ^2' ) iridium (III) acetylacetonate (abbreviation: Ir (ppy) ₂ (acac)), bis (benzo [ h] Kinolinato) Iridium (III) Acetylacetonate (abbreviation: Ir (bz)
q) ₂ (acac)), Tris (benzo [h] quinolinato) iridium (III) (abbreviation: Ir (bzq) ₃ ), tris (2-phenylquinolinato-N, C ^2' ) iridium (I)
II) (abbreviation: Ir (pq) ₃ ), pyridine skeleton such as bis (2-phenylquinolinato-N, C ^2' ) iridium (III) acetylacetonate (abbreviation: Ir (pq) ₂ (acac)) In addition to the organic metal iridium complex having the above, a rare earth metal complex such as tris (acetylacetonato) (monophenanthrolin) terbium (III) (abbreviation: Tb (acac) ₃ (Phen)) can be mentioned. These are compounds that mainly exhibit green phosphorescence emission and have emission peaks in the range of 500 nm to 600 nm. Among the above, the organometallic iridium complex having a diazine skeleton such as pyrimidine and pyrazine has a weak hole trapping property.
Highly electronic trapping property. Therefore, these compounds are used as the first phosphorescent compound in the light emitting element of one aspect of the present invention, the first light emitting layer is provided on the anode side of the second light emitting layer, and the second light emitting layer. When the layer is electron-transporting (specifically, when the second host material is an electron-transporting material), it is preferable because the recombination region of the carrier can be easily controlled in the first light emitting layer. .. The organometallic iridium complex having a pyrimidine skeleton is particularly preferable because it is remarkably excellent in reliability and luminous efficiency.

In addition, bis [4,6-bis (3-methylphenyl) pyrimidinato] (diisobutyrylmethano) iridium (III) (abbreviation: Ir (5mdppm) ₂ (divm)), bis [4.
6-Bis (3-Methylphenyl) pyrimidinato] (Dipivaloylmethanato) Iridium (
III) (Abbreviation: Ir (5mdppm) ₂ (dpm)), Bis [4,6-di (naphthalene-1-yl) pyrimidinato] (Dipivaloylmethanato) Iridium (III) (abbreviation: I)
Organometallic iridium complexes with a pyrimidine skeleton such as r (d1npm) ₂ (dpm)) and (acetylacetonato) bis (2,3,5-triphenylpyrazinato) iridium (III) (abbreviation: Ir (abbreviation: Ir) tppr) ₂ (acac)), bis (2,3,5-triphenylpyridinato) (dipivaloylmethanato) iridium (III) (abbreviation: Ir (tppr)
) ₂ (dpm)), (acetylacetonato) bis [2,3-bis (4-fluorophenyl) quinoxalinato] iridium (III) (abbreviation: Ir (Fdpq) ₂ (acac)) with a pyrazine skeleton. Organic metal iridium complex, tris (1-phenylisoquinolinato-N, C ^2' ) iridium (III) (abbreviation: Ir (piq) ₃ ), bis (1-phenylisoquinolinato-N, C ^2' ) In addition to organic metal iridium complexes with a pyridine skeleton such as iridium (III) acetylacetonate (abbreviation: Ir (piq) ₂ (acac)), 2,3,7,8,12,13,17,18-octaethyl Platinum complexes such as -21H, 23H-porphyrin platinum (II) (abbreviation: PtOEP) and tris (1,3-diphenyl-1,3-propanedionat) (monophenanthroline) europium (III).
) (Abbreviation: Eu (DBM) ₃ (Phen)), Tris [1- (2-tenoyle) -3,3
Examples include rare earth metal complexes such as 3-trifluoroacetonato] (monophenanthroline) europium (III) (abbreviation: Eu (TTA) ₃ (Phen)). These are compounds that exhibit red phosphorescence emission and have emission peaks from 600 nm to 700 nm. Among the above, the organometallic iridium complex having a diazine skeleton such as pyrimidine and pyrazine has a weak hole trapping property and a high electron trapping property. Therefore, an organic metal iridium complex having a diazine skeleton is used as the second phosphorescent compound, the first light emitting layer is provided on the cathode side of the second light emitting layer, and the second light emitting layer is a hole. When transportable (specifically, when the second host material is a hole transport material), the carrier recombination region is set to the first.
It is preferable because it is easy to control in the light emitting layer of. The organometallic iridium complex having a pyrimidine skeleton is particularly preferable because it is remarkably excellent in reliability and luminous efficiency. Further, since the organometallic iridium complex having a pyrazine skeleton can obtain red light emission with good chromaticity, the color rendering property can be enhanced when applied to a white light emitting element.

Further, in addition to the phosphorescent compounds described above, among known phosphorescent light emitting materials, a first phosphorescent material and a second phosphorescent material having the relationship as shown in the first embodiment are selected. It may be selected and used.

The phosphorescent compound (first phosphorescent compound 113a and second phosphorescent compound 1)
Instead of 13b), a material that exhibits thermally activated delayed fluorescence, i.e., Thermally Activated Delayed Fluorescence (TADF)
) Materials may be used. Here, delayed fluorescence refers to light emission having a spectrum similar to that of normal fluorescence, but having a significantly long lifetime. Its life is ^10-6 seconds or longer, preferably ^10-3 .
More than a second. Specific examples of the thermally activated delayed fluorescent material include fullerenes and derivatives thereof, acridine derivatives such as proflavine, and eosin. Also, magnesium (Mg)
), Zinc (Zn), Cadmium (Cd), Tin (Sn), Platinum (Pt), Indium (I)
n), or metal-containing porphyrins containing palladium (Pd) and the like can be mentioned. Examples of the metal-containing porphyrin include a protoporphyrin-tin fluoride complex (abbreviation: Sn).
F ₂ (Proto IX)), mesoporphyrin-tin fluoride complex (abbreviation: SnF ₂ (M)
eso IX)), hematoporphyrin-tin fluoride complex (abbreviation: SnF ₂ (Hemat))
o IX)), coproporphyrin tetramethyl ester-tin fluoride complex (abbreviation: Sn)
F ₂ (Copro III-4Me)), octaethylporphyrin-tin fluoride complex (
Abbreviation: SnF ₂ (OEP)), etioporphyrin-tin fluoride complex (abbreviation: SnF ₂ (abbreviation: SnF 2)
Etio I)), Octaethylporphyrin-platinum chloride complex (abbreviation: PtCl ₂ (OE)
P)) and the like. In addition, 2- (biphenyl-4-yl) -4,6-bis (12-)
Phenylindro [2,3-a] Carbazole-11-yl) -1,3,5-triazine (abbreviation: PIC-TRZ) and other π-rich heteroaromatic rings and π-deficient heterocyclic rings Compounds can also be used. In addition, in the substance in which the π-rich heteroaromatic ring and the π-deficient heteroaromatic ring are directly bonded, both the donor property of the π-rich heteroaromatic ring and the acceptor property of the π _- deficient heteroaromatic ring become stronger, and S1 and This is particularly preferable because the energy difference of T ₁ is small.

The materials that can be used as the first and second host materials are not particularly limited, and various carrier transport materials may be selected and appropriately combined so as to obtain the device structure shown in FIG. ..

For example, as a host material having electron transportability, bis (10-hydroxybenzo [h]]
Kinolinato) 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) phenolato] zinc (II) (abbreviation: ZnPBO), bis [2- (2-benzothiazolyl) phenolato] zinc (II) (abbreviation: ZnBTZ) Metal complexes such as 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole (abbreviation: PBD), 3- (4-biphenylyl) -4- Phenyl-5- (4-tert-butylphenyl) -1,2,4-triazole (abbreviation: TAZ), 1,3-bis [5- (p)
-Tert-Butylphenyl) -1,3,4-oxadiazole-2-yl] benzene (
Abbreviation: OXD-7), 9- [4- (5-phenyl-1,3,4-oxadiazole-2-)
Il) Phenyl] -9H-carbazole (abbreviation: CO11), 2,2', 2''-(1,
3,5-Benzenetriyl) Tris (1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2- [3- (dibenzothiophen-4-yl) phenyl] -1-phenyl-1H-benzimidazole (abbreviation: TPBI) Abbreviation: mDBTBIm-II) and other heterocyclic compounds having a polyazole skeleton, 2- [3- (dibenzothiophen-4-yl) phenyl] dibenzo [f, h] quinoxaline (abbreviation: 2mDBTPDBq-II), 2- [ 3'-(dibenzothiophen-4-yl) biphenyl-3-yl] dibenzo [f, h] quinoxalin (abbreviation: 2mDBTBPDBq-II), 2- [3'-(9H-carbazole-9-yl) biphenyl-3 -Il] dibenzo [f, h] quinoxalin (abbreviation: 2mCzBPDBq),
4,6-bis [3- (phenanthrene-9-yl) phenyl] pyrimidine (abbreviation: 4,6)
Heterocyclic compounds having a diazine skeleton such as mPnP2Pm), 4,6-bis [3- (4-dibenzothienyl) phenyl] pyrimidine (abbreviation: 4,6mDBTP2Pm-II), and
3,5-bis [3- (9H-carbazole-9-yl) phenyl] pyridine (abbreviation: 35)
Examples thereof include heterocyclic compounds having a pyridine skeleton such as DCzPPy), 1,3,5-tri [3- (3-pyridyl) -phenyl] benzene (abbreviation: TmPyPB). Among the above, the heterocyclic compound having a diazine skeleton and the 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 has high electron transport properties and contributes to a reduction in driving voltage.

As a host material having hole transportability, 4,4'-bis [N- (1-naphthyl))
-N-Phenylamino] Biphenyl (abbreviation: NPB), 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: BSPB), 4-phenyl-4'-(9-phenylfluorene-9-yl) triphenylamine (abbreviation: BPAFLP), 4-phenyl-
3'-(9-Phenylfluorene-9-yl) triphenylamine (abbreviation: mBPAFL)
P), 4-Phenyl-4'-(9-Phenyl-9H-Carbazole-3-yl) Triphenylamine (abbreviation: PCBA1BP), 4,4'-Diphenyl-4''-(9-Phenyl-9H-) Carbazole-3-yl) 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),
9,9-Dimethyl-N-Phenyl-N- [4- (9-Phenyl-9H-Carbazole-3)
-Il) Phenyl] Fluorene-2-amine (abbreviation: PCBAF), N-Phenyl-N-
[4- (9-Phenyl-9H-carbazole-3-yl) phenyl] Spiro-9,9'-
Compounds having an aromatic amine skeleton such as bifluorene-2-amine (abbreviation: PCBASF), 1,3-bis (N-carbazolyl) benzene (abbreviation: mCP), 4,4'-di (N)
-Carbazole) Biphenyl (abbreviation: CBP), 3,6-bis (3,5-diphenylphenyl) -9-phenylcarbazole (abbreviation: CzTP), 3,3'-bis (9-phenyl-9H-carbazole) ( Compounds with a carbazole skeleton such as (abbreviation: PCCP),
4,4', 4''-(benzene-1,3,5-triyl) tri (dibenzothiophene) (
Abbreviation: DBT3P-II), 2,8-diphenyl-4- [4- (9-phenyl-9H-fluorene-9-yl) phenyl] dibenzothiophene (abbreviation: DBTFLP-III),
Compounds having a thiophene skeleton such as 4- [4- (9-phenyl-9H-fluoren-9-yl) phenyl] -6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and 4,4', 4'' -(Benzene-1,3,5-triyl) tri (dibenzofuran) (abbreviation: DBF3P-II), 4- {3- [3- (9-phenyl-9H-fluoren-9-yl) phenyl] phenyl} dibenzofuran Examples thereof include compounds having a furan skeleton such as (abbreviation: mmDBFFLBi-II). Among the above-mentioned compounds, the compound having an aromatic amine skeleton and the compound having a carbazole skeleton are preferable because they have good reliability, high hole transportability, and contribute to reduction of driving voltage.

Further, in addition to the host material described above, a host material may be used from known substances. As the host material, it is preferable to select a substance having a triplet level larger than the triplet level (energy difference between the ground state and the triplet excited state) of the phosphorescent compound. again,
It is preferable that these host materials do not have an absorption spectrum in the blue region. Specifically, it is preferable that the absorption edge of the absorption spectrum is 440 nm or less.

The light emitting layer 113 having the above structure can be produced by co-depositing by a vacuum vapor deposition method or by using an inkjet method, a spin coating method, a dip coating method or the like as a mixed solution.

The electron transport layer 114 is a layer containing an electron transportable substance. For example, tris (8-quinolinolato) aluminum (abbreviation: Alq), tris (4-methyl-8-quinolinolato) aluminum (abbreviation: Almq ₃ ), bis (10-hydroxybenzo [h] quinolinato) berylium (abbreviation: BeBq ₂ ). ), Bis (2-methyl-8-quinolinolat) (4-phenylphenolato) aluminum (abbreviation: BAlq), etc., is a layer composed of a metal complex having a quinoline skeleton or a benzoquinoline skeleton. In addition, bis [2- (2-hydroxyphenyl) benzoxazolato] zinc (abbreviation: Zn (BOX) ₂ ), bis [2- (2-hydroxyphenyl) benzothiazolato] zinc (abbreviation: Zn (BTZ)) Oxazole-based and thiazole-based metal complexes such as ₂ ) 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-oxadiazole-2-yl] benzene (abbreviation: OXD-) 7
), 3- (4-Biphenylyl) -4-phenyl-5- (4-tert-butylphenyl)
-1,2,4-Triazole (abbreviation: TAZ), Basophenanthroline (abbreviation: BPhe)
n), basocuproin (abbreviation: BCP) and the like can also be used. The substances described here have high electron transport properties and mainly have electron mobilities of ^10-6 cm ² / Vs or more. The electron transporting host material described above may be used for the electron transport layer 114.

Further, the electron transport layer 114 may be not only a single layer but also a layer in which two or more layers made of the above substances are laminated.

Further, a layer for controlling the movement of electron carriers may be provided between the electron transport layer and the light emitting layer.
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.

Further, an electron injection layer 115 may be provided between the electron transport layer 114 and the second electrode 102 in contact with the second electrode 102. The electron injection layer 115 includes lithium fluoride (LiF),
Alkali metals or alkaline earth metals such as cesium fluoride (CsF), calcium fluoride (CaF ₂ ), or compounds thereof can be used. For example, an alkali metal, an alkaline earth metal, or a compound thereof contained in a layer made of a substance having an electron transport property can be used. By using the electron injection layer 115 in which an alkali metal or an alkaline earth metal is contained in a layer made of a substance having electron transporting property, electron injection from the second electrode 102 is efficiently performed. Therefore, it is more preferable.

The substance forming the second electrode 102 has a small work function (specifically, 3.8 eV).
Below) Metals, alloys, electrically conductive compounds, and mixtures thereof can be used. Specific examples of such a cathode material include alkali metals such as lithium (Li) and cesium (Cs), magnesium (Mg), calcium (Ca), and strontium (Sr).
Elements belonging to Group 1 or Group 2 of the Periodic Table of the Elements, etc., and alloys containing these (MgAg)
, AlLi), europium (Eu), ytterbium (Yb) and other rare earth metals and alloys containing these. However, by providing an electron injection layer between the second electrode 102 and the electron transport layer, indium-tin oxide containing Al, Ag, ITO, silicon or silicon oxide is provided regardless of the size of the work function. Various conductive materials such as second
Can be used as the electrode 102 of. These conductive materials can be formed into a film by using a sputtering method, an inkjet method, a spin coating method, or the like.

Further, as a method for forming the EL layer 103, various methods can be used regardless of whether it is a dry method or a wet method. For example, a vacuum vapor deposition method, an inkjet method, a spin coating method, or the like may be used. Further, it may be formed by using a different film forming method for each electrode or each layer.

The electrode may also be formed by a wet method using a sol-gel method, or may be formed by a wet method using a paste of a metal material. Further, it may be formed by using a dry method such as a sputtering method or a vacuum vapor deposition method.

In the light emitting element having the above configuration, a current flows due to the potential difference generated between the first electrode 101 and the second electrode 102, and holes are formed in the light emitting layer 113 which is a layer containing a highly luminescent substance. And electrons recombine and emit light. That is, the structure is such that a light emitting region is formed on the light emitting layer 113.

The light emission is taken out through either or both of the first electrode 101 and the second electrode 102. Therefore, either or both of the first electrode 101 and the second electrode 102 are made of translucent electrodes. When only the first electrode 101 is a translucent electrode, the light emission is taken out through the first electrode 101. Further, when only the second electrode 102 is a translucent electrode, the light emission is taken out through the second electrode 102. When both the first electrode 101 and the second electrode 102 are translucent electrodes, light emission is taken out from both through the first electrode 101 and the second electrode 102.

The structure of the layer provided between the first electrode 101 and the second electrode 102 is not limited to the above. However, holes and electrons are generated at locations away from the first electrode 101 and the second electrode 102 so that the quenching caused by the proximity of the light emitting region to the metal used for the electrode and the carrier injection layer is suppressed. It is preferable to provide a light emitting region in which the electrons recombine.

Further, the hole transport layer and the electron transport layer in contact with the light emitting layer 113, particularly the carrier transport layer in contact with the light emitting layer 113 closer to the light emitting region, suppresses energy transfer from excitons generated in the light emitting layer. It is preferable that the bandgap is composed of a light emitting material constituting the light emitting layer or a material having a bandgap larger than the bandgap of the light emitting center material contained in the light emitting layer.

The light emitting element in this embodiment may be manufactured on a substrate made of glass, plastic, or the like. As the order of forming on the substrate, the layers may be stacked in order from the first electrode 101 side or in order from the second electrode 102 side. The light emitting device may have one light emitting element formed on one substrate, or may have a plurality of light emitting elements formed. By manufacturing a plurality of such light emitting elements on one substrate, it is possible to manufacture a lighting device in which the elements are divided or a passive matrix type light emitting device. Further, for example, a thin film transistor (TFT) may be formed on a substrate made of glass, plastic, or the like, and a light emitting element may be manufactured on an electrode electrically connected to the TFT. This makes it possible to manufacture an active matrix type light emitting device that controls the driving of the light emitting element by the TFT. The structure of the TFT is not particularly limited. Stagger type TF
It may be T or a reverse stagger type TFT. Further, the crystallinity of the semiconductor used for the TFT is not particularly limited, and an amorphous semiconductor or a crystalline semiconductor may be used. Further, the drive circuit formed on the TFT substrate may be composed of N-type and P-type TFTs, or may be composed of only one of N-type TFTs and P-type TFTs. good.

It should be noted that this embodiment can be appropriately combined with other embodiments.

(Embodiment 3)
In this embodiment, a light emitting device using the light emitting element according to the first embodiment and the second embodiment will be described.

In the present embodiment, a light emitting device manufactured by using the light emitting element according to the first embodiment and the second embodiment will be described with reference to FIG. 4 (A) is a top view showing a light emitting device, and FIG. 4 (B) is a cross-sectional view of FIG. 4 (A) cut by AB and CD. This light emitting device includes a drive circuit unit (source line drive circuit) 601, a pixel unit 602, and a drive circuit unit (gate line drive circuit) 603 shown by dotted lines to control the light emission of the light emitting element. Further, 604 is a sealing substrate, 625 is a desiccant, 605 is a sealing material, and the inside surrounded by the sealing material 605 is a space 607.

The routing wiring 608 is a wiring for transmitting signals input to the source line drive circuit 601 and the gate line drive circuit 603, and is a video signal, a clock signal, and a video signal and a clock signal from the FPC (flexible print circuit) 609 which is an external input terminal. Receives start signal, reset signal, etc. Although only the FPC is shown here, a printed wiring board (PWB) may be attached to the FPC. The light emitting device in the present specification includes not only the light emitting device main body but also a state in which an FPC or PWB is attached to the light emitting device main body.

Next, the cross-sectional structure will be described with reference to FIG. 4 (B). A drive circuit unit and a pixel unit are formed on the element substrate 610, but here, the source line drive circuit 601 which is a drive circuit unit is formed.
, One pixel in the pixel unit 602 is shown.

The source line drive circuit 601 includes an n-channel type TFT 623 and a p-channel type TFT 62.
A CMOS circuit in combination with 4 is formed. Further, the drive circuit may be formed of various CMOS circuits, polyclonal circuits or IMS circuits. Further, in the present embodiment, the driver integrated type in which the drive circuit is formed on the substrate is shown, but it is not always necessary, and the drive circuit can be formed on the outside instead of on the substrate.

Further, the pixel unit 602 is formed by a plurality of pixels including a switching TFT 611, a current control TFT 612, and a first electrode 613 electrically connected to the drain thereof.
An insulator 614 is formed so as to cover the end portion of the first electrode 613. Here, it is formed by using a positive type photosensitive acrylic resin film.

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 insulating material 614. For example, when positive photosensitive acrylic is used as the material of the insulating material 614, it is preferable that only the upper end portion of the insulating material 614 has a curved surface having a radius of curvature (0.2 μm to 3 μm). Further, as the insulating material 614, a negative type photosensitive resin,
Alternatively, any positive type photosensitive resin can be used.

An EL layer 616 and a second electrode 617 are formed on the first electrode 613, respectively. Here, as the material used for the first electrode 613 that functions as an anode, it is desirable to use a material having a large work function. For example, an ITO film, an indium tin oxide film containing silicon, an indium oxide film containing 2 to 20 wt% zinc oxide, a titanium nitride film, and the like.
In addition to single-layer films such as chrome film, tungsten film, Zn film, and Pt film, lamination of titanium nitride and aluminum-based film, titanium nitride film, aluminum-based film, and titanium nitride film A three-layer structure or the like can be used. It should be noted that the laminated structure has low resistance as wiring, good ohmic contact can be obtained, and can further function as an anode.

Further, the EL layer 616 is formed by various methods such as a thin-film deposition method using a thin-film deposition mask, an inkjet method, and a spin coating method. The EL layer 616 has the first embodiment and the second embodiment.
Includes the configuration described in. Further, as another material constituting the EL layer 616,
It may be a low molecular weight compound or a high molecular weight compound (including an oligomer and a dendrimer).

Further, as the material used for the second electrode 617 formed on the EL layer 616 and functioning as a cathode, a material having a small work function (Al, Mg, Li, Ca, or an alloy or compound thereof, MgAg, MgIn, etc. It is preferable to use AlLi or the like). The EL layer 616
When the light generated in the above is transmitted through the second electrode 617, the second electrode 617 is a thin metal thin film and a transparent conductive film (ITO, indium oxide containing 2 to 20 wt% zinc oxide. , Indium tin oxide containing silicon, zinc oxide (ZnO), etc.).

A light emitting element is formed by the first electrode 613, the EL layer 616, and the second electrode 617. The light emitting element is the light emitting element according to the first embodiment and the second embodiment. Although a plurality of light emitting elements are formed in the pixel portion, in the light emitting device according to the present embodiment, the light emitting elements according to the first and second embodiments and the light emitting elements having other configurations are provided. Both of the elements may be included.

Further, by bonding the sealing substrate 604 to the element substrate 610 with the sealing material 605,
The structure is such that the light emitting element 618 is provided in the space 607 surrounded by the element substrate 610, the sealing substrate 604, and the sealing material 605. The space 607 is filled with a filler, and may be filled with an inert gas (nitrogen, argon, etc.) or a sealing material 605. If a recess is formed in the sealing substrate and a desiccant 625 is provided therein, deterioration due to the influence of moisture can be suppressed, which is a preferable configuration.

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 allow moisture or oxygen to permeate as much as possible. In addition to glass substrates and quartz substrates, FRP (Fiberg) can be used as the material for the sealing substrate 604.
A plastic substrate made of lass-Reinforced Plastics), PVF (polyvinyl fluoride), polyester, acrylic or the like can be used.

As described above, a light emitting device manufactured by using the light emitting element according to the first embodiment and the second embodiment can be obtained.

Since the light emitting device in the present embodiment uses the light emitting elements according to the first and second embodiments, it is possible to obtain a light emitting device having good characteristics. Specifically, it is a light emitting element having good light emitting efficiency shown in the first and second embodiments, and can be a light emitting device having reduced power consumption. Further, it is a light emitting element having a small drive voltage, and a light emitting device having a small drive voltage can be obtained.

As described above, in the present embodiment, the active matrix type light emitting device has been described, but in addition to this, a passive matrix type light emitting device may be used. FIG. 5 shows a passive matrix type light emitting device manufactured by applying the present invention. 5 (A) is a perspective view showing a light emitting device, and FIG. 5 (B) is a cross-sectional view of FIG. 5 (A) cut by XY. In FIG. 5,
An EL layer 955 is provided between the electrode 952 and the electrode 956 on the substrate 951.
The end of the electrode 952 is covered with an insulating layer 953. Then, the partition wall layer 9 is placed on the insulating layer 953.
54 is provided. The side wall of the partition wall layer 954 has an inclination such that the distance between one side wall and the other side wall becomes narrower as it gets closer to the substrate surface. That is, the cross section in the short side direction of the partition wall layer 954 is trapezoidal, and the bottom side (the side facing the same direction as the surface direction of the insulating layer 953 and in contact with the insulating layer 953) is the upper side (the surface of the insulating layer 953). Insulating layer 9 facing in the same direction as the direction
It is shorter than the side that does not touch 53). By providing the partition wall layer 954 in this way, it is possible to prevent defects in the light emitting element due to static electricity and the like. Further, the passive matrix type light emitting device can also be driven with low power consumption by having the light emitting elements according to the first and second embodiments that operate at a low driving voltage. Further, by having the light emitting element according to the first embodiment and the second embodiment, it is possible to obtain a highly reliable light emitting device.

Further, in order to display in full color, a coloring layer or a color conversion layer may be provided on the optical path for the light from the light emitting element to go out of the light emitting device. FIGS. 6A and 6B show examples of a light emitting device that has been made full-color by providing a colored layer or the like. In FIG. 6A, the substrate 1001
Underlayer insulating film 1002, gate insulating film 1003, gate electrodes 1006, 1007, 1008
, First interlayer insulating film 1020, second interlayer insulating film 1021, peripheral portion 1042, pixel portion 10
40, drive circuit unit 1041, first electrode of light emitting element 1024W, 1024R, 1024G
1024B, a partition wall 1025, an EL layer 1028, a second electrode 1029 of a light emitting element, a sealing substrate 1031, a sealing material 1032, and the like are shown. In addition, the colored layer (red colored layer 10)
34R, the green colored layer 1034G, and the blue colored layer 1034B) are provided on the transparent base material 1033. Further, a black layer (black matrix) 1035 may be further provided. The transparent base material 1033 provided with the colored layer and the black layer is aligned and fixed to the substrate 1001.
The colored layer and the black layer are covered with the overcoat layer 1036. Further, in the present embodiment, there is a light emitting layer in which light is emitted to the outside without passing through the colored layer and a light emitting layer in which light is transmitted to the outside through the colored layer of each color and does not pass through the colored layer. Since the light is white and the light transmitted through the colored layer is red, blue, and green, an image can be expressed by pixels of four colors.

Further, in the light emitting device described above, the light emitting device has a structure that extracts light to the substrate 1001 side on which the TFT 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 light emitting device. A cross-sectional view of the top emission type light emitting device is shown in FIG. In this case, the substrate 1001 can be a substrate that does not transmit light. Until the connection electrode for connecting the TFT and the anode of the light emitting element is manufactured, it is formed in the same manner as the bottom emission type light emitting device. After that, a third interlayer insulating film 1037 is formed so as to cover the electrode 1022. The third interlayer insulating film 1037 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 other known materials.

The first electrode 1024W, 1024R, 1024G, 1024B of the light emitting element is used as an anode here, but may be a cathode. Further, in the case of the top emission type light emitting device as shown in FIG. 7, it is preferable that the first electrode is a reflecting electrode. The structure of the EL layer 1028 is as described in the first and second embodiments, and the element structure is such that white light emission can be obtained. When two EL layers are used, blue light can be obtained from the light emitting layer in one EL layer, and orange light can be obtained from the light emitting layer in the other EL layer. The composition and the blue light from the light emitting layer in one EL layer is the other E.
It is conceivable that the light emitting layer in the L layer can obtain red and green light. Further, when three EL layers are used, a light emitting element exhibiting white light emission can be obtained by making it possible to obtain red, green, and blue light emission from each light emitting layer. Of course, if the configurations shown in the first and second embodiments are applied, the configuration for obtaining white light emission is not limited to this.

The colored layer is provided on an optical path through which the light from the light emitting element goes out. In the case of the bottom emission type light emitting device as shown in FIG. 6A, the colored layer 1034R, 1034 is formed on the transparent base material 1033.
It can be provided by providing G and 1034B and fixing them to the substrate 1001. Further, as shown in FIG. 6B, the colored layer may be provided between the gate insulating film 1003 and the first interlayer insulating film 1020. If it has a top emission structure as shown in FIG. 7, it can be sealed with a sealing substrate 1031 provided with a colored layer (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B). The sealing substrate 1031 may be provided with a black layer (black matrix) 1035 so as to be located between the pixels. The colored layer (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B) and the black layer (black matrix) 1035 may be covered with the overcoat layer 1036.
The sealing substrate 1031 uses a transparent substrate.

When a voltage is applied between the pair of electrodes of the organic light emitting element thus obtained, the white light emitting region 10
44W is obtained. In addition, by combining with the colored layer, the red light emitting region 1044R and
A blue light emitting region 1044B and a green light emitting region 1044G are obtained. Since the light emitting device of the present embodiment uses the light emitting elements according to the first and second embodiments, it is possible to realize a light emitting device having low power consumption.

Further, although an example of performing full-color display in four colors of red, green, blue, and white is shown here, the present invention is not particularly limited, and full-color display may be performed in three colors of red, green, and blue. Further, the color purity may be improved by providing a microcavity structure. At this time, the microcavity structure may be provided in all the pixels, but may be provided only in the blue pixels.

Moreover, this embodiment can be freely combined with other embodiments.

(Embodiment 4)
In this embodiment, an example of using the light emitting element described in the first embodiment and the second embodiment as a lighting device will be described with reference to FIG. 8 (B) is a top view of the lighting device, and FIG. 8 (A) is a cross-sectional view taken along the line ef in FIG. 8 (B).

The lighting device in the present embodiment is the first on a translucent substrate 400 which is a support.
Electrode 401 is formed. The first electrode 401 is the first electrode 1 in the third embodiment.
Corresponds to 01.

An auxiliary electrode 402 is provided on the first electrode 401. In this embodiment, since an example of extracting light emission from the first electrode 401 side is shown, the first electrode 401 is formed of a translucent material. The auxiliary electrode 402 is provided to compensate for the low conductivity of the translucent material, and suppresses the uneven brightness in the light emitting surface due to the voltage drop due to the high resistance of the first electrode 401. Has the function of The auxiliary electrode 402 is formed by using at least a material having a higher conductivity than the material of the first electrode 401, and preferably by using a material having a higher conductivity such as aluminum. It is preferable that the surface of the auxiliary electrode 402 other than the portion in contact with the first electrode 401 is covered with an insulating layer. This is to suppress light emission from the upper part of the auxiliary electrode 402 that cannot be taken out, to reduce reactive current, and to suppress a decrease in power efficiency. At the same time as the formation of the auxiliary electrode 402, the second electrode 404
A pad 412 for supplying a voltage to the device may be formed.

An EL layer 403 is formed on the first electrode 401 and the auxiliary electrode 402. EL layer 40
3 has the configurations described in the first and second embodiments. Please refer to the description for these configurations. It is preferable that the EL layer 403 is formed to be slightly larger than the first electrode 401 when viewed in a plane, because it can also serve as an insulating layer for suppressing a short circuit between the first electrode 401 and the second electrode 404. It is a composition.

A second electrode 404 is formed by covering the EL layer 403. The second electrode 404 is the third embodiment.
Corresponds to the second electrode 102 in the above, and has a similar configuration. In the present embodiment, since the light emission is taken out from the first electrode 401 side, it is preferable that the second electrode 404 is formed of a material having high reflectance. In the present embodiment, the second electrode 404 is a pad 4
It is assumed that the voltage is supplied by connecting with 12.

As mentioned above, the first electrode 401, the EL layer 403, and the second electrode 404 (and the auxiliary electrode 402)
) Is included in the lighting device shown in the present embodiment. Since the light emitting element is a light emitting element having high luminous efficiency, the lighting device in the present embodiment can be a lighting device having low power consumption. Further, since the light emitting element is a highly reliable light emitting element, the lighting device according to the present embodiment can be a highly reliable lighting device.

The lighting device is completed by fixing the sealing substrate 407 to the light emitting element having the above configuration by using the sealing materials 405 and 406 and sealing the light emitting element. Either one of the sealing materials 405 and 406 may be used. In addition, a desiccant can be mixed with the inner sealing material 406, whereby moisture can be adsorbed, which leads to improvement in reliability.

Further, a part of the pad 412, the first electrode 401 and the auxiliary electrode 402 is sealed with the sealing material 405.
By extending it to the outside of the 406, it can be used as an external input terminal. Further, an IC chip 420 or the like on which a converter or the like is mounted may be provided on the IC chip 420.

As described above, since the lighting device according to the present embodiment has the light emitting element according to the first embodiment and the second embodiment in the EL element, the lighting device can be a lighting device having low power consumption. Further, the lighting device can be a lighting device having a low drive voltage. In addition, it can be a highly reliable lighting device.

(Embodiment 5)
In this embodiment, an example of an electronic device including the light emitting element according to the first embodiment and the second embodiment as a part thereof will be described. The light emitting element according to the first embodiment and the second embodiment is a light emitting element having good luminous efficiency and reduced power consumption. As a result, the electronic device described in the present embodiment can be an electronic device having a light emitting unit with reduced power consumption. Further, since the light emitting element according to the first embodiment and the second embodiment is a light emitting element having a small drive voltage, it can be an electronic device having a small drive voltage.

Examples of electronic devices to which the above light emitting element is applied include television devices (also referred to as televisions or television receivers), monitors for computers, digital cameras, digital video cameras, digital photo frames, mobile phones (mobile phones, etc.). (Also referred to as a mobile phone device), a portable game machine, a mobile information terminal, a sound reproduction device, a large game machine such as a pachinko machine, and the like. Specific examples of these electronic devices are shown below.

FIG. 9A shows an example of a television device. The television device is a housing 710.
A display unit 7103 is incorporated in 1. Further, here, a configuration in which the housing 7101 is supported by the stand 7105 is shown. An image can be displayed by the display unit 7103, and the display unit 7103 is configured by arranging the light emitting elements according to the first and second embodiments in a matrix. The light emitting element can be a light emitting element having good luminous efficiency. Further, it is possible to use a light emitting element having a small drive voltage. Further, it is possible to use a light emitting element having a long life. Therefore, the display unit 7 composed of the light emitting element
The television device having 103 can be a television device with reduced power consumption. Further, it is possible to use a television device having a small drive voltage. In addition, it can be a highly reliable television device.

The operation of the television device can be performed by an operation switch included in the housing 7101 or a separate remote control operation machine 7110. Operation key 7109 provided in the remote controller 7110
This allows you to control the channel and volume, and you can control the image displayed on the display unit 7103. Further, the remote controller 7110 is attached to the remote controller 7110.
A display unit 7107 for displaying information output from the device may be provided.

The television device shall be configured to include a receiver, a modem, and the like. The receiver can receive general television broadcasts, and by connecting to a wired or wireless communication network via a modem, one-way (sender to receiver) or two-way (sender and receiver). It is also possible to perform information communication between (or between receivers, etc.).

FIG. 9B1 is a computer, which includes a main body 7201, a housing 7202, a display unit 7203, a keyboard 7204, an external connection port 7205, a pointing device 7206, and the like. It should be noted that this computer is manufactured by arranging light emitting elements similar to those described in the second embodiment or the third embodiment in a matrix and using them in the display unit 7203. Figure 9 (
The computer of B1) may have the form shown in FIG. 9 (B2). The computer of FIG. 9B2 is provided with a second display unit 7210 instead of the keyboard 7204 and the pointing device 7206. The second display unit 7210 is a touch panel type, and input can be performed by operating the input display displayed on the second display unit 7210 with a finger or a dedicated pen. Further, the second display unit 7210 can display not only the input display but also other images. Further, the display unit 7203 may also be a touch panel. By connecting the two screens with a hinge, it is possible to prevent troubles such as damage or damage to the screens during storage or transportation. The light emitting element can be a light emitting element having good luminous efficiency. Therefore, the computer having the display unit 7203 composed of the light emitting element can be a computer with reduced power consumption.

FIG. 9C shows a portable gaming machine, which is composed of two housings, a housing 7301 and a housing 7302, and is connected by a connecting portion 7303 so as to be openable and closable. A display unit 7304 manufactured by arranging the light emitting elements described in the first and second embodiments in a matrix is incorporated in the housing 7301, and the display unit 7305 is incorporated in the housing 7302. .. In addition, the portable gaming machine shown in FIG. 9C has a speaker unit 7306 and a recording medium insertion unit 7307.
, LED lamp 7308, input means (operation key 7309, connection terminal 7310, sensor 73
11 (force, displacement, position, speed, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, voice, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, It includes a function to measure inclination, vibration, odor or infrared rays), microphone 7312) and the like. Of course, the configuration of the portable game machine is not limited to the above, and at least the display unit 73.
A display unit made by arranging the light emitting elements according to the first and second embodiments in a matrix may be used for both or one of the 04 and the display unit 7305, and other accessory equipment may be appropriately provided. Can be configured. The portable gaming machine shown in FIG. 9C has a function of reading a program or data recorded on a recording medium and displaying it on a display unit, and wirelessly communicates with other portable gaming machines to share information. Has a function. The functions of the portable gaming machine shown in FIG. 9C are not limited to this, and can have various functions. The portable gaming machine having the display unit 7304 as described above can be a portable gaming machine with reduced power consumption because the light emitting element used in the display unit 7304 has good luminous efficiency. can. Further, since the light emitting element used in the display unit 7304 can be driven with a low drive voltage, it is possible to make a portable gaming machine having a small drive voltage. Further, since the light emitting element used in the display unit 7304 is a light emitting element having a long life, it can be a highly reliable portable gaming machine.

FIG. 9D shows an example of a mobile phone. In addition to the display unit 7402 built into the housing 7401, the mobile phone has an operation button 7403, an external connection port 7404, and a speaker 74.
It is equipped with 05, a microphone 7406, and the like. The mobile phone 7400 has a display unit 7402 manufactured by arranging the light emitting elements according to the first and second embodiments in a matrix. The light emitting element can be a light emitting element having good luminous efficiency. again,
It is possible to use a light emitting element having a small drive voltage. Further, it is possible to use a light emitting element having a long life. Therefore, the mobile phone having the display unit 7402 composed of the light emitting element can be a mobile phone with reduced power consumption. Further, it is possible to use a mobile phone having a small drive voltage. Moreover, it is possible to make a highly reliable mobile phone.

The mobile phone shown in FIG. 9D may be configured so that information can be input by touching the display unit 7402 with a finger or the like. In this case, operations such as making a phone call or composing an e-mail can be performed by touching the display unit 7402 with a finger or the like.

The screen of the display unit 7402 mainly has three modes. The first is a display mode mainly for displaying an image, and the second is an input mode mainly for inputting information such as characters. The third is a display + input mode in which two modes, a display mode and an input mode, are mixed.

For example, when making a phone call or composing an e-mail, the display unit 7402 may be set to a character input mode mainly for inputting characters, and the characters displayed on the screen may be input. In this case, it is preferable to display the keyboard or the number button on most of the screen of the display unit 7402.

Further, by providing a detection device having a sensor for detecting the inclination of a gyro, an acceleration sensor, etc. inside the mobile phone, the orientation (vertical or horizontal) of the mobile phone is determined, and the screen display of the display unit 7402 is automatically displayed. It is possible to switch to the target.

Further, the screen mode can be switched by touching the display unit 7402 or by operating the operation button 7403 of the housing 7401. It is also possible to switch depending on the type of the image displayed on the display unit 7402. For example, if the image signal displayed on the display unit is moving image data, the display mode is switched, and if the image signal is text data, the input mode is switched.

Further, in the input mode, the signal detected by the optical sensor of the display unit 7402 is detected, and if there is no input by the touch operation of the display unit 7402 for a certain period of time, the screen mode is switched from the input mode to the display mode. You may control it.

The display unit 7402 can also function as an image sensor. For example, the display unit 74
By touching 02 with a palm or a finger and taking an image of a palm print, a fingerprint, or the like, personal authentication can be performed. Further, if a backlight that emits near-infrared light or a sensing light source that emits near-infrared light is used for the display unit, it is possible to image finger veins, palmar veins, and the like.

The configurations shown in the present embodiment can be used by appropriately combining the configurations shown in the first to fourth embodiments.

As described above, the range of application of the light emitting device provided with the light emitting element according to the first and second embodiments is extremely wide, and this light emitting device can be applied to electronic devices in all fields.
By using the light emitting element according to the first embodiment and the second embodiment, it is possible to obtain an electronic device having reduced power consumption.

FIG. 10 is an example of a liquid crystal display device in which the light emitting element according to the first and second embodiments is applied to a backlight. The liquid crystal display device shown in FIG. 10 has a housing 901 and a liquid crystal layer 902.
, The backlight unit 903, the housing 904, and the liquid crystal layer 902 is the driver IC 90.
It is connected to 5. Further, the light emitting element according to the first embodiment and the second embodiment is used in the backlight unit 903, and a current is supplied from the terminal 906.

By applying the light emitting element according to the first embodiment and the second embodiment to the backlight of the liquid crystal display device, a backlight with reduced power consumption can be obtained. Further, by using the light emitting element according to the second embodiment, a surface light emitting lighting device can be manufactured, and the area can be increased. As a result, the area of the backlight can be increased, and the area of the liquid crystal display device can be increased. Further, since the light emitting device to which the light emitting element according to the second embodiment is applied can have a smaller thickness than the conventional one, the display device can be made thinner.

FIG. 11 is an example in which the light emitting element according to the first embodiment and the second embodiment is used for a desk lamp which is a lighting device. The desk lamp shown in FIG. 11 has a housing 2001 and a light source 2002.
As the light source 2002, the light emitting device according to the fourth embodiment is used.

In FIG. 12, the light emitting element according to the first embodiment and the second embodiment is used as an indoor lighting device 300.
1 and an example used as a display device 3002. Since the light emitting element according to the first embodiment and the second embodiment is a light emitting element having reduced power consumption, it can be a lighting device having reduced power consumption. Further, since the light emitting element according to the first embodiment and the second embodiment can have a large area, it can be used as a lighting device having a large area. Further, since the light emitting element according to the first embodiment and the second embodiment is thin, it can be used as a thin lighting device.

The light emitting element according to the first embodiment and the second embodiment can also be mounted on a windshield or a dashboard of an automobile. FIG. 13 shows an aspect in which the light emitting element according to the second embodiment is used for a windshield or a dashboard of an automobile. Display 5000 to Display 5005
Is a display provided by using the light emitting element according to the first embodiment and the second embodiment.

The display 5000 and the display 5001 are display devices equipped with the light emitting elements according to the first and second embodiments provided on the windshield of the automobile. The light emitting element according to the first embodiment and the second embodiment is a so-called see-through state display device in which the opposite side can be seen through by manufacturing the first electrode and the second electrode with electrodes having translucency. Can be. If the display is in a see-through state, even if it is installed on the windshield of an automobile, it can be installed without obstructing the view. When a transistor for driving is provided, it is preferable to use a transistor having translucency, such as an organic transistor made of an organic semiconductor material or a transistor using an oxide semiconductor.

The display 5002 is a display device provided with the light emitting element according to the first embodiment and the second embodiment provided in the pillar portion. The display 5002 can complement the field of view blocked by the pillars by projecting an image from an image pickup means provided on the vehicle body. Similarly, the display 5003 provided on the dashboard portion can supplement the blind spot and enhance the safety by projecting the image from the image pickup means provided on the outside of the automobile in the field of view blocked by the vehicle body. can. By projecting the image so as to complement the invisible part, it is possible to confirm the safety more naturally and without discomfort.

The display 5004 and the display 5005 can provide various other information such as navigation information, a speedometer or tachometer, a mileage, a refueling amount, a gear state, and an air conditioner setting. The display items and layout can be changed as appropriate according to the user's preference. It should be noted that these information can also be provided on the display 5000 to the display 5003.
Further, the display 5000 to the display 5005 can also be used as a lighting device.

The light emitting element according to the first embodiment and the second embodiment can be a light emitting element having high luminous efficiency. Further, the light emitting element having low power consumption can be used. From this, display 5
Even if a large number of large screens such as 000 to display 5005 are provided, the load on the battery is small and the battery can be used comfortably. Therefore, light emission using the light emitting element according to the first and second embodiments. The device or lighting device can be suitably used as an in-vehicle light emitting device or lighting device.

14 (A) and 14 (B) are examples of tablet terminals that can be folded in half. Figure 1
Reference numeral 4 (A) is an open state, and the tablet-type terminal has a housing 9630 and a display unit 9631a.
9631b, display mode changeover switch 9034, power supply switch 9035, power saving mode changeover switch 9036, fastener 9033, operation switch 9038. The tablet terminal is manufactured by using the light emitting device provided with the light emitting element according to the first and second embodiments for one or both of the display unit 9631a and the display unit 9631b.

A part of the display unit 9631a can be a touch panel area 9632a, and data can be input by touching the displayed operation key 9637. Display unit 963
In 1a, as an example, a configuration in which half of the area has a display-only function and the other half of the area has a touch panel function are shown, but the configuration is not limited to this. Display unit 963
All areas of 1a may be configured to have a touch panel function. For example, display unit 96
The entire surface of 31a can be displayed as a keyboard button to form a touch panel, and the display unit 9631b can be used as a display screen.

Further, in the display unit 9631b as well, a part of the display unit 9631b can be a touch panel area 9632b, similarly to the display unit 9631a. Further, the keyboard button can be displayed on the display unit 9631b by touching the position where the keyboard display switching button 9639 on the touch panel is displayed with a finger or a stylus.

Further, touch input can be simultaneously performed on the touch panel area 9632a and the touch panel area 9632b.

Further, the display mode changeover switch 9034 can switch the display direction such as vertical display or horizontal display, and can select switching between black-and-white display and color display. The power saving mode changeover switch 9036 can optimize the brightness of the display according to the amount of external light during use detected by the optical sensor built in the tablet terminal. The tablet-type terminal may incorporate not only an optical sensor but also another detection device such as a gyro, an acceleration sensor, or other sensor for detecting tilt.

Further, FIG. 14A shows an example in which the display areas of the display unit 9631b and the display unit 9631a are the same, but the display area is not particularly limited, and one size and the other size may be different, and the display quality is also good. It may be different. For example, one may be a display panel capable of displaying a higher definition than the other.

FIG. 14B shows a closed state. In the tablet terminal according to the present embodiment, the housing 9630, the solar cell 9633, the charge / discharge control circuit 9634, the battery 9635, and the DCD are shown.
An example including a C converter 9636 is shown. In addition, in FIG. 14B, the charge / discharge control circuit 963
As an example of 4, a configuration having a battery 9635 and a DCDC converter 9636 is shown.

Since the tablet terminal can be folded in half, the housing 9630 can be closed when not in use. Therefore, since the display unit 9631a and the display unit 9631b can be protected,
It is possible to provide a tablet-type terminal that has excellent durability and is highly reliable from the viewpoint of long-term use.

In addition to this, the tablet-type terminal shown in FIGS. 14 (A) and 14 (B) has a function of displaying various information (still images, moving images, text images, etc.), a calendar, a date, a time, and the like. It can have a function of displaying on a display unit, a touch input function of performing a touch input operation or editing information displayed on the display unit, a function of controlling processing by various software (programs), and the like.

The solar cell 9633 mounted on the surface of the tablet terminal can supply electric power to the touch panel, the display unit, the video signal processing unit, or the like. The solar cell 9633 can be provided on one side or both sides of the housing 9630, and can be configured to efficiently charge the battery 9635.

Further, the configuration and operation of the charge / discharge control circuit 9634 shown in FIG. 14B are described in FIG. 14 (B).
A block diagram will be shown and described in C). In FIG. 14C, the solar cell 9633 and the battery 9 are shown.
635, DCDC converter 9636, converter 9638, switches SW1 to SW3
, Display unit 9631, battery 9635, DCDC converter 963.
6. The converter 9638 and the switches SW1 to SW3 correspond to the charge / discharge control circuit 9634 shown in FIG. 14B.

First, an example of operation when power is generated by the solar cell 9633 by external light will be described. The power generated by the solar cell is DC so that it becomes the voltage for charging the battery 9635.
The DC converter 9636 steps up or down. Then, when the electric power charged by the solar cell 9633 is used for the operation of the display unit 9631, the switch SW1 is turned on, and the converter 9638 steps up or down the voltage required for the display unit 9631. Further, when the display is not performed on the display unit 9631, the SW1 may be turned off and the SW2 may be turned on to charge the battery 9635.

Although the solar cell 9633 is shown as an example of the power generation means, the power generation means is not particularly limited, and the battery 9635 is charged by another power generation means such as a piezoelectric element (piezo element) or a thermoelectric conversion element (Peltier element). It may be configured to perform the above. A non-contact power transmission module that wirelessly (non-contactly) transmits and receives power to charge the battery, or a configuration in which other charging means are combined may be used, and it is not necessary to have a power generation means.

Further, as long as the display unit 9631 is provided, the present invention is not limited to the tablet-type terminal having the shape shown in FIG.

In this embodiment, a method and characteristics for manufacturing a light emitting device corresponding to one aspect of the present invention described in the first embodiment and the second embodiment will be described. The structural formulas of the organic compounds used in this example are shown below.

Next, a method for manufacturing the light emitting device of this embodiment will be shown.

First, indium tin oxide (ITSO) containing silicon oxide was formed on a glass substrate by a sputtering method to form a first electrode 101. The film thickness was 110 nm, and the electrode area was 2 mm × 2 mm. Here, the first electrode 101 is an electrode that functions as an anode of the light emitting element.

Next, as a pretreatment for forming a light emitting element on the substrate, the surface of the substrate is washed with water, and 200
After firing at ° C. for 1 hour, UV ozone treatment was performed for 370 seconds.

After that, the substrate was introduced into a vacuum vapor deposition apparatus whose internal pressure was reduced to about 10 ^-4 Pa, vacuum fired at 170 ° C. for 30 minutes in a heating chamber inside the vacuum vapor deposition apparatus, and then the substrate was released for about 30 minutes. It was chilled.

Next, the substrate on which the first electrode 101 is formed is fixed to a substrate holder provided in the vacuum vapor deposition apparatus so that the surface on which the first electrode 101 is formed faces downward, and is about 10 ^-4 Pa. After depressurizing to ) Tri (dibenzothiophene) (abbreviation: DBT3P-II) and molybdenum oxide (VI) were co-deposited to form the hole injection layer 111. The film thickness was 33 nm, and the ratio of DBT3P-II to molybdenum oxide was adjusted to be 4: 2 (= DBT3P-II: molybdenum oxide) by weight. The co-deposited method is a vapor deposition method in which vapor deposition is performed simultaneously from a plurality of evaporation sources in one processing chamber.

Next, on the hole injection layer 111, 4-phenyl-4'-(represented by the above structural formula (ii))
9-Phenylfluorene-9-yl) Triphenylamine (abbreviation: BPAFLP) 20
The hole transport layer 112 was formed by forming a film so as to have a film thickness of nm.

Further, on the hole transport layer 112, 2- [3- (dibenzothiophen-4-yl) phenyl] dibenzo [f, h] quinoxaline (abbreviation: 2mDBT) represented by the above structural formula (iii).
PDBq-II) and 4-phenyl-4'-(9-phenyl-9H-carbazole-3-yl) triphenylamine (abbreviation: PCBA1BP) represented by the above structural formula (iv) and the above structural formula (v). Bis [2- (6-tert-butyl-4-pyrimidinyl-κN3) represented by
) Phenyl-κC] (2,4-pentanedionato-κ ² O, O') Iridium (III)
(Abbreviation: Ir (tBuppm) ₂ (acac)) and weight ratio 0.8: 0.2: 0.05
(= 2mDBTPDBq-II: PCBA1BP: Ir (tBuppm) ₂ (acac)
) To be 20 nm co-deposited to form the first light emitting layer 113a, 2 mDBTPDBq-I.
I and bis (2,3,5-triphenylpyrazinato) (dipyvaloylmethanato) iridium (III) (abbreviation: Ir (tppr) ₂ (dpm)) represented by the above structural formula (vi). , Weight ratio 1: 0.06 (= 2mDBTPDBq-II: Ir (tppr) ₂ (dpm))
The second light emitting layer 113b was formed by co-depositing 20 nm so as to be. The host materials 2mDBTPDBq-II and PCBA1BP form an excited complex.

Then, 2mDBTPDBq-II is formed on the light emitting layer 113 so as to have a film thickness of 15 nm, and further, vasophenanthroline (abbreviation: BPhen) represented by the above structural formula (vii) is formed.
Was formed to a thickness of 15 nm to form an electron transport layer 114.

After the electron transport layer 114 was formed, lithium fluoride (LiF) was vapor-deposited to a film thickness of 1 nm to form the electron injection layer 115.

Finally, as the second electrode 102 that functions as a cathode, aluminum was vapor-deposited so as to have a film thickness of 200 nm to produce the light emitting device 1 of the present embodiment.

In the above-mentioned vapor deposition process, the resistance heating method was used for all the vapor deposition.

Table 1 shows the element structure of the light emitting element 1 obtained as described above.

The light emitting element 1 is sealed with a glass substrate in a glove box having a nitrogen atmosphere so as not to be exposed to the atmosphere (a sealing material is applied around the element and heat-treated at 80 ° C. for 1 hour at the time of sealing). rice field.

In the light emitting device 1, Ir (tBuppm) ₂ (ac) is used as the first phosphorescent compound 113Da.
ac), Ir (tppr) ₂ (dpm) is used as the second phosphorescent compound 113Db. Here, the PL spectrum of Ir (tBuppm) ₂ (acac) and Ir (tp).
The relationship between ε (λ) λ ⁴ of pr) ₂ (dpm) will be described. Note that λ is the wavelength and ε (λ) is the molar extinction coefficient.

First, in FIG. 20 (a), the molar extinction coefficient ε (λ) of Ir (tppr) ₂ (dpm) and ε (λ)
) A graph representing λ ⁴ is shown. The molar extinction coefficient ε (λ) does not have a conspicuous peak in the long wavelength region, whereas the graph of ε (λ) λ ⁴ has a peak (mountain) having a maximum value at 543 nm. This peak is the triplet ML of Ir (tppr) ₂ (dpm).
It is CT absorption, and by superimposing the emission peak of the first phosphorescent compound 113Da on this peak, it is possible to greatly improve the efficiency of energy transfer.

FIG. 20 (b) shows Ir (tBuppm) ₂ (ac), which is the first phosphorescent compound 113Da.
PL spectrum F (λ) of ac) and Ir (tpp) which is the second phosphorescent compound 113Db.
r) A graph showing ε (λ) λ ⁴ of ₂ (dpm) is shown. From this graph, Ir (tBu)
ppm) ₂ (acac) PL spectrum F (λ) peak present and Ir (tpp)
r) ₂ (dpm) ε (λ) λ ⁴ has a large overlap with the mountain having the maximum value on the longest wavelength side, and it can be seen that the combination is such that energy transfer is performed very efficiently. again,
The emission peak of Ir (tBuppm) ₂ (acac), which is the first phosphorescent compound 113Da, exists at 546 nm, and Ir (tppr) ₂ which is the second phosphorescent compound 113Db exists.
Since the maximum on the long wavelength side in the spectrum representing ε (λ) λ ⁴ of (dpm) exists at 543 nm, the difference is 3 nm. 546nm is 2.27eV, 543nm is 2.28e
Since it corresponds to V, the difference is 0.01 eV, which is smaller than 0.2 eV, suggesting that efficient energy transfer is performed even from the peak position.

Subsequently, in FIG. 21 (a), Ir (tBuppm) 2, which is the first phosphorescent compound 113Da, ₂
A graph showing the molar extinction coefficient ε (λ) of (acac) and ε (λ) λ ⁴ is shown. The peak in the long wavelength region in the graph showing the molar extinction coefficient ε (λ) has a smaller intensity than the peak in the short wavelength side, whereas in the graph of ε (λ) λ ⁴ , it is 494 nm. There is a maximum value with great strength in. The peak (mountain) where this maximum value exists is Ir (tBu).
It is a triplet MLCT absorption of ppm) ₂ (acac), and by superimposing the emission peak of the energy donor on this peak, it is possible to greatly improve the efficiency of energy transfer.

Here, in the light emitting device 1 of this embodiment, 2mDBTPDBq-II, which is the first host material, is used.
And PCBA1BP, which is the first organic compound, form an excited complex 113Ec, and energy is supplied from the excited complex 113Ec to the first phosphorescent compound 113Da. FIG. 23 is a diagram showing the PL spectra of 2mDBTPDBq-II, PCBA1BP, and a mixed film thereof (0.8: 0.2 in terms of mass ratio), and is a diagram showing 2mDBTPDBq.
It can be seen that -II and PCBA1BP, which is the first organic compound, form an excited complex 113Ec. Further, FIG. 21B shows a graph showing the PL spectrum F (λ) of the excited complex and ε (λ) λ ⁴ of Ir (tBuppm) ₂ (acac) which is the first phosphorescent compound 113Da. rice field. From this graph, the peak of the PL spectrum F (λ) of the excited complex and the peak of Ir (tBuppm) ₂ (acac) ε (λ) λ ⁴ on the longest wavelength side overlap. It can be seen that this is a combination in which energy transfer is efficiently performed. Further, the peak of the PL spectrum of the excited complex exists at 519 nm, and is the maximum on the long wavelength side in the spectrum representing ε (λ) λ ⁴ of Ir (tBuppm) ₂ (acac), which is the first phosphorescent compound 113Da. Is at 494 nm, so the difference is 25 nm. Since 519 nm corresponds to 2.39 eV when converted to energy and 494 nm corresponds to 2.51 eV when converted to energy, the difference is 0.12 eV, which is smaller than 0.2 eV, so that it is efficient even from the peak position. It is suggested that energy transfer takes place.

As can be seen from FIG. 23, 2mDBTPDBq, which is the first host material 113Ha.
The peak of the PL spectrum of -II is 426 nm, which is 2.91 in terms of energy.
Corresponds to eV. Further, the peak of the PL spectrum of PCBA1BP, which is the first organic compound 113A, is 405 nm, which corresponds to 3.06 eV in terms of energy. Ir
Since the maximum value on the long wavelength side in the spectrum representing ε (λ) λ ⁴ of (tBuppm) ₂ (acac) exists at 494 nm, it corresponds to 2.51 eV in terms of energy, and the difference between them is 0.4 eV. (First host material 113Ha: 2mDBTPDBq-II),
It becomes 0.55 eV (first organic compound 113A: PCBA1BP), and both are 0.2 e.
Since it has an energy difference of V or more, it can be seen that it is difficult to transfer energy from 2mDBTPDBq-II and PCBA1BP to Ir (tBuppm) ₂ (acac).

Further, in FIG. 22, PL spectra F (λ) and Ir (tBuppm) ₂ (acac) of the excited complex are shown.
) PL spectrum F (λ), Ir (tppr) ₂ (dpm) PL spectrum F (λ)
, Ir (tBuppm) ₂ (acac) ε (λ) λ ⁴ , Ir (tppr) ₂ (dpm)
The graph which put together ε (λ) λ ⁴ of ε (λ) λ 4 is shown. PL spectrum of excited complex and Ir (tB)
uppm) ₂ (acac) from the excited complex to Ir (tBuppm) ₂ (acac) using the overlap with ε (λ) λ ⁴ (near the maximum value A), and Ir (tBuppm) ₂ (aca).
Ir (tBuppm) ₂ (acac) to Ir (tppr) ₂ (dp) using the overlap (near the maximum value B) between the PL spectrum of c) and ε (λ) λ ⁴ of Ir (tppr) ₂ (dpm).
It can be seen that energy transfer is possible in stages to m). From the excited complex, the second
It is also possible to transfer energy directly to Ir (tppr) ₂ (dpm), which is a phosphorescent compound of. This is the triplet ML of Ir (tppr) ₂ (dpm), as can be seen from FIG.
On the short wavelength side of the CT absorption band (near the maximum value B), both the PL spectrum F (λ) of the excited complex are Ir.
This is because ε (λ) λ ⁴ of (tppr) ₂ (dpm) overlap.

The element characteristics of this light emitting element were measured. The measurement was performed at room temperature (atmosphere maintained at 25 ° C.).

The luminance-current efficiency characteristic of the light emitting element 1 is shown in FIG. In FIG. 15, the horizontal axis is luminance (cd /
m ² ), the vertical axis represents the current efficiency (cd / A). Further, the voltage-luminance characteristic is shown in FIG. In FIG. 16, the horizontal axis represents voltage (V) and the vertical axis represents luminance (cd / m ² ). Further, the luminance-external quantum efficiency characteristics are shown in FIG. In FIG. 17, the horizontal axis represents luminance (cd / m ² ) and the vertical axis represents external quantum efficiency (%). Further, the brightness-power efficiency characteristic is shown in FIG. In FIG. 18,
The horizontal axis shows the brightness (cd / m ² ), and the vertical axis shows the power efficiency (%).

As described above, it was found that the light emitting element 1 exhibits good element characteristics. In particular, FIGS. 15 and 1
7. As can be seen from FIG. 18, it has very good luminous efficiency, and the external quantum efficiency is practical brightness (
A high value of 20% or more was shown in the vicinity of 1000 cd / m ² ). Similarly, the current efficiency is about 60 cd / A, and the power efficiency is about 60 lm / W, which are very good values.

Further, FIG. 19 shows an emission spectrum when a current of 0.1 mA is passed through the light emitting element 1. In FIG. 19, the horizontal axis represents wavelength (nm) and the vertical axis represents emission intensity (arbitrary unit). From FIG.
The light emitting device 1 is a bis [2- (6-tert-butyl-4-pyrimidinyl-κN3) phenyl-κC] (2,4-pentanedionato-κ ² O, O') iridium (III) (abbreviation: I).
Green wavelength light and bis (2,3,5-triphenylpyrazinato) (dipyvaloylmethanato) iridium (III) (abbreviation: Ir (tp)) derived from r (tBuppm) ₂ (acac))
It was found that the emission spectrum showed a well-balanced inclusion of light having a red wavelength derived from pr) ₂ (dpm)).

As described above, it was found that the light emitting device 1 corresponding to one aspect of the present invention is a light emitting device having good luminous efficiency and obtaining light from two kinds of light emitting center substances in a well-balanced manner.

In this embodiment, a method and characteristics for manufacturing a light emitting device corresponding to one aspect of the present invention described in the first embodiment and the second embodiment will be described. The structural formulas of the organic compounds used in this example are shown below.

Next, a method for manufacturing the light emitting device of this embodiment will be shown.

First, indium tin oxide (ITSO) containing silicon oxide was formed on a glass substrate by a sputtering method to form a first electrode 101. The film thickness was 110 nm, and the electrode area was 2 mm × 2 mm. Here, the first electrode 101 is an electrode that functions as an anode of the light emitting element.

Next, as a pretreatment for forming a light emitting element on the substrate, the surface of the substrate is washed with water, and 200
After firing at ° C. for 1 hour, UV ozone treatment was performed for 370 seconds.

After that, the substrate was introduced into a vacuum vapor deposition apparatus whose internal pressure was reduced to about 10 ^-4 Pa, vacuum fired at 170 ° C. for 30 minutes in a heating chamber inside the vacuum vapor deposition apparatus, and then the substrate was released for about 30 minutes. It was chilled.

Next, the substrate on which the first electrode 101 is formed is fixed to a substrate holder provided in the vacuum vapor deposition apparatus so that the surface on which the first electrode 101 is formed faces downward, and is about 10 ^-4 Pa. After depressurizing to, the above structural formula (viii) was applied on the first electrode 101 by a vapor deposition method using resistance heating.
), 3- [4- (9-Phenyltril) -phenyl] -9-phenyl-9H-carbazole (abbreviation: PCPPn), and molybdenum oxide (VI) are co-deposited to form a hole injection layer 111. Formed. The film thickness was 33.3 nm, and the ratio of PCPPn to molybdenum oxide was adjusted to be 1: 0.5 (= PCPPn: molybdenum oxide) by weight. The co-deposited method is a vapor deposition method in which vapor deposition is performed simultaneously from a plurality of evaporation sources in one processing chamber.

Next, on the hole injection layer 111, 4-phenyl-4'-(represented by the above structural formula (ii))
9-Phenylfluorene-9-yl) Triphenylamine (abbreviation: BPAFLP) 20
The hole transport layer 112 was formed by forming a film so as to have a film thickness of nm.

Further, on the hole transport layer 112, 2- [3'-(dibenzothiophen-4-yl) biphenyl-3-yl] dibenzo [f, h] quinoxalin represented by the above structural formula (ix) (abbreviation:: 2mDBTBPDBq-II) and 4,4'-di (1-naphthyl) -4 "- (9-phenyl-9H-carbazole-3-yl) triphenylamine represented by the above structural formula (x) (abbreviation:: PCBNBB) and the bis [2- (6-tert-butyl-4-pyrimidinyl-κN3) phenyl-κC] represented by the above structural formula (v) (2,4-pentanedionato-κ ² O).
, O') Iridium (III) (abbreviation: Ir (tBuppm) ₂ (acac)) and weight ratio 0.8: 0.2: 0.06 (= 2mDBTBPDBq-II: PCBNBB: Ir (
tBuppm) ₂ (acac)) 20 nm co-deposited so that the first light emitting layer 113a
2mDBTBPDBq-II and the screw (2,3,5-) represented by the above structural formula (vi).
Triphenylpyradinato) (Dipivaloylmethanato) Iridium (III) (abbreviation: Ir
(Tppr) ₂ (dpm)) with a weight ratio of 1: 0.06 (= 2mDBTBPDBq-II)
: Ir (tppr) ₂ (dpm)) 20 nm co-deposited so that the second light emitting layer 113
b was formed. The host materials 2mDBTBPDBq-II and PCBNBB form an excited complex.

Then, 2mDBTBPDBq-II is formed on the light emitting layer 113 so as to have a film thickness of 15 nm, and further, vasophenanthroline (abbreviation: BPhen) represented by the above structural formula (vii) is formed.
) Was formed into a film having a thickness of 15 nm to form an electron transport layer 114.

After the electron transport layer 114 was formed, lithium fluoride (LiF) was vapor-deposited to a film thickness of 1 nm to form the electron injection layer 115.

Finally, as the second electrode 102 that functions as a cathode, aluminum was vapor-deposited so as to have a film thickness of 200 nm to produce the light emitting device 2 of this embodiment.

In the above-mentioned vapor deposition process, the resistance heating method was used for all the vapor deposition.

Table 2 shows the element structure of the light emitting element 2 obtained as described above.

The light emitting element 2 is sealed with a glass substrate in a glove box having a nitrogen atmosphere so as not to be exposed to the atmosphere (a sealing material is applied around the element and heat-treated at 80 ° C. for 1 hour at the time of sealing). rice field.

In the light emitting device 2, as in the light emitting device 1, Ir (tB) is used as the first phosphorescent compound 113Da.
uppm) ₂ (acac) as Ir (tppr) as the second phosphorescent compound 113Db.
₂ (dpm) is used. Therefore, regarding the relationship between the PL spectrum of Ir (tBuppm) ₂ (acac) and ε (λ) λ ⁴ of Ir (tppr) ₂ (dpm), the light emitting device 1
Since it is the same as, the repeated explanation is omitted. Please refer to the description regarding FIGS. 20 (a) and 20 (b) of the first embodiment. As described above, the first phosphorescent compound 113 in the light emitting device 2
It is suggested that the energy transfer between Da and the second phosphorescent compound 113Db is efficient.

The element characteristics of this light emitting element were measured. The measurement was performed at room temperature (atmosphere maintained at 25 ° C.).

The luminance-current efficiency characteristics of the light emitting element 2 are shown in FIG. 24. Further, the voltage-luminance characteristic is shown in FIG. Further, the luminance-external quantum efficiency characteristics are shown in FIG. In addition, the brightness-power efficiency characteristics are shown in FIG. 27.
Shown in.

As described above, it was found that the light emitting element 2 exhibits good element characteristics. In particular, FIGS. 24 and 2
6. As can be seen from FIG. 27, it has a very good luminous efficiency, and the external quantum efficiency is practical brightness (
A high value of 20% or more was shown in the vicinity of 1000 cd / m ² ). Similarly, the current efficiency is around 60 cd / A, and the power efficiency is around 60 lm / W, which are very good values.

Further, FIG. 28 shows an emission spectrum when a current of 0.1 mA is passed through the light emitting element 2. From FIG. 28, the light emitting device 2 is bis [2- (6-tert-butyl-4-pyrimidineyl-κN3).
) Phenyl-κC] (2,4-pentanedionato-κ ² O, O') Iridium (III)
(Abbreviation: Ir (tBuppm) ₂ (acac))-derived green wavelength light and bis (2,3)
5-Triphenylpyrazinato) (Dipivaloylmethanato) Iridium (III) (abbreviation:
It was found that the emission spectrum showed a well-balanced inclusion of light having a red wavelength derived from Ir (tppr) ₂ (dpm)).

Further, the initial brightness is 5000 cd / m ² , and the initial brightness is 100 under the condition that the current density is constant.
The result of the reliability test in the case of is shown in FIG. 29. From FIG. 29, the light emitting element 2 has 96% of the initial brightness after 70 hours, despite the reliability test of the initial brightness of 5000 cd / m ² .
It was found that it is a light emitting element with good reliability.

As described above, it was found that the light emitting device 2 corresponding to one aspect of the present invention is a light emitting device having good luminous efficiency and obtaining light from two kinds of light emitting center substances in a well-balanced manner. Furthermore, it was found that the light emitting device has a good reliability and a long life.

In this embodiment, a method and characteristics for manufacturing a light emitting device corresponding to one aspect of the present invention described in the first embodiment and the second embodiment will be described. The structural formulas of the organic compounds used in this example are shown below.

Next, a method for manufacturing the light emitting device of this embodiment will be shown.

First, indium tin oxide (ITSO) containing silicon oxide was formed on a glass substrate by a sputtering method to form a first electrode 101. The film thickness was 110 nm, and the electrode area was 2 mm × 2 mm. Here, the first electrode 101 is an electrode that functions as an anode of the light emitting element.

Next, as a pretreatment for forming a light emitting element on the substrate, the surface of the substrate is washed with water, and 200
After firing at ° C. for 1 hour, UV ozone treatment was performed for 370 seconds.

After that, the substrate was introduced into a vacuum vapor deposition apparatus whose internal pressure was reduced to about 10 ^-4 Pa, vacuum fired at 170 ° C. for 30 minutes in a heating chamber inside the vacuum vapor deposition apparatus, and then the substrate was released for about 30 minutes. It was chilled.

Next, the substrate on which the first electrode 101 is formed is fixed to a substrate holder provided in the vacuum vapor deposition apparatus so that the surface on which the first electrode 101 is formed faces downward, and is about 10 ^-4 Pa. After depressurizing to ) Tri (dibenzothiophene) ((abbreviation: DBT3P-II)) and molybdenum oxide (VI) were co-deposited to form a hole injection layer 111. The film thickness was 40 nm, and it was oxidized with DBT3P-II. The ratio of molybdenum was adjusted to be 4: 2 (= DBT3P-II: molybdenum oxide) by weight. In the co-deposited method, vapor deposition is simultaneously performed from a plurality of evaporation sources in one processing chamber. It is a vapor deposition method.

Next, on the hole injection layer 111, a film thickness of 4,4', 4''-tri (N-carbazolyl) triphenylamine (abbreviation: TCTA) represented by the above structural formula (xi) is 10 nm. The hole transport layer 112 was formed by forming a film so as to be.

Further, on the hole transport layer 112, TCTA and a screw represented by the above structural formula (vi) (2, 3)
, 5-Triphenylpyrazinato) (dipivaloylmethanato) Iridium (III) (abbreviation: Ir (tppr) ₂ (dpm)) with a weight ratio of 1: 0.1 (= TCTA: Ir (tpp))
r) ₂ (dpm)) is co-deposited with 10 nm to form the second light emitting layer 113b, which is represented by the above structural formula (iii) and is 2- [3- (dibenzothiophen-4-yl) phenyl] dibenzo. [F, h] Quinoxaline (abbreviation: 2mDBTPDBq-II) and the above structural formula (iv).
4-Phenyl-4'-(9-phenyl-9H-carbazole-3-yl) triphenylamine (abbreviation: PCBA1BP) represented by and bis [2- (6) represented by the above structural formula (v).
-Tert-Butyl-4-pyrimidinyl-κN3) Phenyl-κC] (2,4-pentanedionato-κ ² O, O') Iridium (III) (abbreviation: Ir (tBuppm) ₂ (ac)
ac)) with a weight ratio of 0.8: 0.2: 0.05 (= 2mDBTPDBq-II: PCB)
The first light emitting layer 113a was formed by co-depositing 5 nm so as to be A1BP: Ir (tBuppm) ₂ (acac)). The host materials 2mDBTPDBq-II and PCB
It forms an excited complex with A1BP.

Then, 2mDBTPDBq-II and Ir (tBuppm) ₂ (aca) on the light emitting layer 113.
c) and 1: 0.05 (= 2mDBTPDBq-II: Ir (tBuppm) ₂ (aca)
c)) is co-deposited at 20 nm, 2 mDBTPDBq-II is formed into a 10 nm film, and vasophenanthroline (abbreviation: BPhen) represented by the above structural formula (vii) is 2
The electron transport layer 114 was formed by forming a film so as to have a thickness of 0 nm.

After the electron transport layer 114 was formed, lithium fluoride (LiF) was vapor-deposited to a film thickness of 1 nm to form the electron injection layer 115.

Finally, as the second electrode 102 that functions as a cathode, aluminum was vapor-deposited so as to have a film thickness of 200 nm to produce the light emitting device 3 of this embodiment.

In the above-mentioned vapor deposition process, the resistance heating method was used for all the vapor deposition.

Table 3 shows the element structure of the light emitting element 3 obtained as described above. The light emitting element 3 is a light emitting element produced by using a material of a hole transport layer and a second host material, which are significantly different from those of the light emitting element 1 and the light emitting element 2. Further, the positions of the first light emitting layer and the second light emitting layer with respect to the electrodes and the structure of the electron transport layer are also significantly different.

The light emitting element 3 is sealed with a glass substrate in a glove box having a nitrogen atmosphere so as not to be exposed to the atmosphere (a sealing material is applied around the element and heat-treated at 80 ° C. for 1 hour at the time of sealing). rice field.

In the light emitting device 3, as in the light emitting device 1, Ir (tB) is used as the first phosphorescent compound 113Da.
uppm) ₂ (acac) as Ir (tppr) as the second phosphorescent compound 113Db.
₂ (dpm) is used. Therefore, regarding the relationship between the PL spectrum of Ir (tBuppm) ₂ (acac) and ε (λ) λ ⁴ of Ir (tppr) ₂ (dpm), the light emitting device 1
Since it is the same as, the repeated explanation is omitted. Please refer to the description regarding FIGS. 20 (a) and 20 (b) of the first embodiment. As described above, the first phosphorescent compound 113 in the light emitting device 3
It is suggested that the energy transfer between Da and the second phosphorescent compound 113Db is efficient.

The element characteristics of this light emitting element were measured. The measurement was performed at room temperature (atmosphere maintained at 25 ° C.).

The luminance-current efficiency characteristics of the light emitting element 3 are shown in FIG. Further, the voltage-luminance characteristic is shown in FIG. Further, the luminance-external quantum efficiency characteristics are shown in FIG. In addition, the brightness-power efficiency characteristics are shown in FIG. 33.
Shown in.

As described above, it was found that the light emitting element 3 exhibits good element characteristics. In particular, FIGS. 30 and 3
2. As can be seen from FIG. 33, it has a very good luminous efficiency, and the external quantum efficiency is practical brightness (
A high value of 20% or more was shown in the vicinity of 1000 cd / m ² ). Similarly, the current efficiency is around 60 cd / A, and the power efficiency is around 70 lm / W, which are very good values.

Further, FIG. 34 shows an emission spectrum when a current of 0.1 mA is passed through the light emitting element 3. From FIG. 34, the light emitting device 3 is bis [2- (6-tert-butyl-4-pyrimidinyl-κN3).
) Phenyl-κC] (2,4-pentanedionato-κ ² O, O') Iridium (III)
(Abbreviation: Ir (tBuppm) ₂ (acac))-derived green wavelength light and bis (2,3)
5-Triphenylpyrazinato) (Dipivaloylmethanato) Iridium (III) (abbreviation:
It was found that the emission spectrum showed a well-balanced inclusion of light having a red wavelength derived from Ir (tppr) ₂ (dpm)).

As described above, the light emitting element 3 corresponding to one aspect of the present invention uses a host material different from that of the light emitting element 1 and the light emitting element 2, but has good luminous efficiency and is composed of two types of light emitting center materials. It was found that it is a luminous element that can obtain the light of the above in a well-balanced manner.

In this embodiment, a method and characteristics for manufacturing a light emitting device corresponding to one aspect of the present invention described in the first embodiment and the second embodiment will be described. The structural formulas of the organic compounds used in this example are shown below.

Next, a method of manufacturing the light emitting element (light emitting element 4, light emitting element 5) of this embodiment will be shown.

First, indium tin oxide (ITSO) containing silicon oxide was formed on a glass substrate by a sputtering method to form a first electrode 101. The film thickness was 110 nm, and the electrode area was 2 mm × 2 mm. Here, the first electrode 101 is an electrode that functions as an anode of the light emitting element.

Next, as a pretreatment for forming a light emitting element on the substrate, the surface of the substrate is washed with water, and 200
After firing at ° C. for 1 hour, UV ozone treatment was performed for 370 seconds.

After that, the substrate was introduced into a vacuum vapor deposition apparatus whose internal pressure was reduced to about 10 ^-4 Pa, vacuum fired at 170 ° C. for 30 minutes in a heating chamber inside the vacuum vapor deposition apparatus, and then the substrate was released for about 30 minutes. It was chilled.

Next, the substrate on which the first electrode 101 is formed is fixed to a substrate holder provided in the vacuum vapor deposition apparatus so that the surface on which the first electrode 101 is formed faces downward, and is about 10 ^-4 Pa. After depressurizing to The hole injection layer 111 was formed by co-depositing phenylamine (abbreviation: BPAFLP) and molybdenum oxide (VI). The film thickness was 33.3 nm, and the ratio of BPAFLP to molybdenum oxide was adjusted to be 1: 0.5 (= BPAFLP: molybdenum oxide) by weight. The co-deposited method is a vapor deposition method in which vapor deposition is performed simultaneously from a plurality of evaporation sources in one processing chamber.

Next, BPAFLP was formed on the hole injection layer 111 so as to have a film thickness of 20 nm to form the hole transport layer 112.

Further, on the hole transport layer 112, 2- [3- (dibenzothiophen-4-yl) phenyl] dibenzo [f, h] quinoxaline (abbreviation: 2mDBT) represented by the above structural formula (iii).
PDBq-II) and 4-phenyl-4'-(9-phenyl-9H-carbazole-3-yl) triphenylamine (abbreviation: PCBA1BP) represented by the above structural formula (iv) and the above structural formula (v). Bis [2- (6-tert-butyl-4-pyrimidinyl-κN3) represented by
) Phenyl-κC] (2,4-pentanedionato-κ ² O, O') Iridium (III)
(Abbreviation: Ir (tBuppm) ₂ (acac)) and weight ratio 0.8: 0.2: 0.06
(= 2mDBTPDBq-II: PCBA1BP: Ir (tBuppm) ₂ (acac)
) To be 20 nm co-deposited to form the first light emitting layer 113a, 2 mDBTPDBq-I.
I and bis {4,6-dimethyl-2- [3- (3,5-dimethylphenyl) -5-phenyl-2-pyrazinyl-κN] phenyl-κC} represented by the above structural formula (xii) (2) , 6-
Dimethyl-3,5-heptandionato-κ ² O, O'') Iridium (III) (abbreviation:
[Ir (dmdppr-P) ₂ (divm)]) with a weight ratio of 1: 0.06 (= 2 mDB)
TPDBq-II: [Ir (dmdppr-P) ₂ (divm)]) 20n
The second light emitting layer 113b was formed by co-depositing m. In addition, 2mDBTPD which is a host material
Bq-II and PCBA1BP form an excited complex.

Then, 2mDBTPDBq-II is formed on the light emitting layer 113 so as to have a film thickness of 15 nm, and further, vasophenanthroline (abbreviation: BPhen) represented by the above structural formula (vii) is formed.
Was formed to a thickness of 15 nm to form an electron transport layer 114.

After the electron transport layer 114 was formed, lithium fluoride (LiF) was vapor-deposited to a film thickness of 1 nm to form the electron injection layer 115.

Finally, as the second electrode 102 that functions as a cathode, aluminum was vapor-deposited so as to have a film thickness of 200 nm to produce the light emitting device 4 of this embodiment.

The light emitting element 5 is a tris [2- (6-tert-butyl-4-pyrimidinyl-κN3) in which [Ir (tBuppm) ₂ (acac)] of the first light emitting layer 113a is represented by the above structural formula (xiii). ) Phenyl-κC] Iridium (III) (abbreviation: [Ir (tBuppm))
It was manufactured in the same manner as the light emitting element 4 except that it was manufactured in place of ₃ )]).

In the above-mentioned vapor deposition process, the resistance heating method was used for all the vapor deposition.

The element structure of the light emitting element 4 obtained as described above is shown in Table 4, and the element structure of the light emitting element 5 is shown in Table 5.

Work of sealing the light emitting element 4 and the light emitting element 5 with a glass substrate in a glove box having a nitrogen atmosphere so as not to be exposed to the atmosphere (a sealing material is applied around the element, and at the time of sealing 8
Heat treatment was performed at 0 ° C. for 1 hour).

In the light emitting device 4, Ir (tBuppm) ₂ (ac) is used as the first phosphorescent compound 113Da.
ac) was used as the second phosphorescent compound 113Db [Ir (dmdppr-P) ₂ (di).
bm)] is used. Here, the relationship between the PL spectrum of Ir (tBuppm) ₂ (acac) and ε (λ) λ ⁴ of [Ir (dmdppr-P) ₂ (divm)] will be described. Note that λ is the wavelength and ε (λ) is the molar extinction coefficient.

First, FIG. 45 (a) shows the second phosphorescent compound 113Db of the light emitting device 4 [Ir (dmd).
A graph showing the molar extinction coefficient ε (λ) of ppr-P) ₂ (divm)] and ε (λ) λ ⁴ is shown. The molar extinction coefficient ε (λ) does not have a conspicuous peak in the long wavelength region, whereas in the graph of ε (λ) λ ⁴ , the maximum value at 509 nm and 550 nm, 605 n
There is a peak (mountain) with a shoulder near m. This peak is [Ir (dmdppr-P)
₂ (divm)] is the triplet MLCT absorption, and the first phosphorescent compound 11 is at this peak.
By superimposing the emission peaks of 3Da, it is possible to greatly improve the efficiency of energy transfer.

FIG. 45 (b) shows Ir (tBupp), which is the first phosphorescent compound 113Da of the light emitting device 4.
m) The graph showing the PL spectrum F (λ) of ₂ (acac) and ε (λ) λ ⁴ of [Ir (dmdppr-P) ₂ (divm)] which is the second phosphorescent compound 113Db is shown. From this graph, the peak of the PL spectrum F (λ) of Ir (tBuppm) ₂ (acac) and the longest wavelength side of ε (λ) λ ⁴ of [Ir (dmdppr-P) ₂ (divm)] It greatly overlaps with the mountain having the maximum value of, and it can be seen that it is a combination in which energy transfer is performed very efficiently. In addition, Ir, which is the first phosphorescent compound 113Da.
The emission peak of (tBuppm) ₂ (acac) is at 546 nm and is in the spectrum representing ε (λ) λ ⁴ of the second phosphorescent compound 113Db [Ir (dmdppr-P) ₂ (divm)]. Since the maximum on the long wavelength side exists at 509 nm, the difference is 37 nm.
Is. Since 546 nm corresponds to 2.27 eV and 509 nm corresponds to 2.44 eV, the difference is 0.17 eV, which is smaller than 0.2 eV, suggesting that efficient energy transfer is performed even from the peak position. Will be done. In addition, [Ir (dmdppr-P) ₂
(Dibm)] The maximum (maximum value C) on the long wavelength side in the spectrum representing ε (λ) λ ⁴ and the spectrum F (λ) of the emission of Ir (tBuppm) ₂ (acac) hardly overlap, but [ The mountain having the maximum value C in the spectrum representing ε (λ) λ ⁴ of Ir (dmdppr-P) ₂ (divm)] has a broad shape on the long wavelength side, and the spectrum on the long wavelength side and Ir ( The spectrum F (λ) of the emission of tBuppm) ₂ (acac) has a large overlap. Therefore, very good energy transfer is realized.

In the light emitting device 4, 2mDBTPDBq-II, which is the first host material, and PCBA1BP, which is the first organic compound, form an excited complex, and Ir, which is the first phosphorescent compound 113Da.
Energy transfer is efficiently performed to (tBuppm) ₂ (acac). Since these relationships are the same as those of the light emitting element 1 and are described in detail in the first embodiment, the repeated description will be omitted. Please refer to the relevant description of Example 1.

Further, in FIG. 46, the PL spectra F (λ) and Ir (tBuppm) ₂ (acac) of the excited complex are shown.
) PL spectrum F (λ), [Ir (dmdppr-P) ₂ (divm)] PL spectrum F (λ), Ir (tBuppm) ₂ (acac) ε (λ) λ ⁴ , [Ir (dmd)
A graph showing ε (λ) λ ⁴ of ppr-P) ₂ (divm)] is shown. Using the overlap (near the maximum value A) between the PL spectrum of the excited complex and ε (λ) λ ⁴ of Ir (tBuppm) ₂ (acac), from the excited complex to Ir (tBuppm) ₂ (acac), and I
PL spectrum of r (tBuppm) ₂ (acac) and [Ir (dmdppr-P) ₂ (
Using the overlap of ε (λ) λ ⁴ of [divm)] with ε (λ) λ 4 (around 650 nm from the maximum value C), Ir (
It can be seen that energy transfer is possible in stages from tBuppm) ₂ (acac) to [Ir (dmdppr-P) ₂ (divm)]. It should be noted that the energy can be directly transferred from the excited complex to the second phosphorescent compound [Ir (dmdppr-P) ₂ (divm)]. As can be seen from FIG. 46, this is [Ir (dmdppr-P) ₂ (div).
m)] in the triplet MLCT absorption band (near the maximum value C), the PL spectrum F (λ) of the excited complex.
This is because ε (λ) λ ⁴ of [Ir (dmdppr-P) ₂ (divm)] overlaps with each other.

In the light emitting device 5, Ir (tBuppm) ₃ is used as the first phosphorescent compound 113Da, and [Ir (dmdppr-P) ₂ (divm)] is used as the second phosphorescent compound 113Db. Here, the PL spectrum of Ir (tBuppm) ₃ and [Ir (dmdppr)
-P) The relationship of ε (λ) λ ⁴ of ₂ (divm)] will be described. Λ is the wavelength, ε (λ)
) Is the molar extinction coefficient.

First, FIG. 47 (a) shows the second phosphorescent compound 113Db of the light emitting device 4 [Ir (dmd).
A graph showing the molar extinction coefficient ε (λ) of ppr-P) ₂ (divm)] and ε (λ) λ ⁴ is shown. The molar extinction coefficient ε (λ) does not have a conspicuous peak in the long wavelength region, whereas in the graph of ε (λ) λ ⁴ , the maximum value at 509 nm and 550 nm, 605 n
There is a peak (mountain) with a shoulder near m. This peak is [Ir (dmdppr-P)
₂ (divm)] is the triplet MLCT absorption, and the first phosphorescent compound 11 is at this peak.
By superimposing the emission peaks of 3Da, it is possible to greatly improve the efficiency of energy transfer.

FIG. 47 (b) shows Ir (tBupp), which is the first phosphorescent compound 113Da of the light emitting device 5.
m) The PL spectrum F (λ) of ₃ and the second phosphorescent compound 113Db [Ir (dm).
A graph showing ε (λ) λ ⁴ of dppr-P) ₂ (divm)] is shown. From this graph, the mountain where the peak of the PL spectrum F (λ) of Ir (tBuppm) ₃ exists and [Ir (dm)
dppr-P) ₂ (divm)] overlaps with the mountain having the maximum value on the longest wavelength side of ε (λ) λ ⁴ , and it can be seen that the energy transfer is very efficient. Further, the emission peak of Ir (tBuppm) ₃ , which is the first phosphorescent compound 113Da, exists at 540 nm, and is the second phosphorescent compound 113Db [Ir (dmdp).
Since the maximum on the long wavelength side in the spectrum representing ε (λ) λ ⁴ of pr−P) ₂ (divm)] exists at 509 nm, the difference is 31 nm. 540nm is 2.30eV, 50
Since 9 nm corresponds to 2.44 eV, the difference is 0.14 eV, which is smaller than 0.2 eV, suggesting that efficient energy transfer is performed even from the peak position. The maximum (maximum value C) on the long wavelength side and the emission spectrum F (λ) of Ir (tBuppm) ₃ in the spectrum representing ε (λ) λ ⁴ of [Ir (dmdppr-P) ₂ (divm)] are Although it hardly overlaps, ε of [Ir (dmdppr-P) ₂ (divm)]
(Λ) The mountain having the maximum value C in the spectrum representing λ ⁴ has a broad shape on the long wavelength side, and the spectrum on the long wavelength side and the spectrum F of the emission of Ir (tBuppm) ₃ (
λ) has a large overlap. Therefore, very good energy transfer is realized.

Subsequently, in FIG. 48A, Ir (tB), which is the first phosphorescent compound 113Da of the light emitting device 5, is shown.
A graph showing the molar extinction coefficient ε (λ) of uppm) ₃ and ε (λ) λ ⁴ is shown. ε (λ)
) In the graph of λ ⁴ , the maximum value having a large intensity at 409 and 465 nm and 49
There is a peak (mountain) with a shoulder at 4 nm. This peak (mountain) is the triplet MLCT absorption of Ir (tBuppm) ₃ , and by superimposing the emission peak of the energy donor on this peak, it is possible to greatly improve the efficiency of energy transfer.

Here, in the light emitting device 5 of this embodiment, 2mDBTPDBq-II, which is the first host material, is used.
And PCBA1BP, which is the first organic compound, form an excited complex 113Ec, and energy is supplied from the excited complex 113Ec to the first phosphorescent compound 113Da. FIG. 23 is a diagram showing the PL spectra of 2mDBTPDBq-II, PCBA1BP, and a mixed film thereof (0.8: 0.2 in terms of mass ratio), and is a diagram showing 2mDBTPDBq.
It can be seen that -II and PCBA1BP, which is the first organic compound, form an excited complex 113Ec. Further, FIG. 48 (b) shows a graph showing the PL spectrum F (λ) of the excited complex and ε (λ) λ ⁴ of Ir (tBuppm) ₃ which is the first phosphorescent compound 113 Da. From this graph, a part of the wavelength range having half the intensity of the peak where the peak of PL spectrum F (λ) of the excited complex exists and the maximum of ε (λ) λ ⁴ of Ir (tBuppm) ₃ on the longest wavelength side. A part of the wavelength range having half the intensity in the mountain having the value overlaps, and it can be seen that the combination is such that energy transfer is efficiently performed.

Further, in FIG. 49, the PL spectrum F (λ) of the excited complex, the PL spectrum F (λ) of Ir (tBuppm) ₃ , and the PL spectrum F (λ) of [Ir (dmdppr-P) ₂ (divm)] are shown.
), Ir (tBuppm) ₃ ε (λ) λ ⁴ , [Ir (dmdppr-P) ₂ (divm)
)] Ε (λ) λ ⁴ is shown in one graph. PL spectrum of excited complex and Ir (
tBuppm) ₃ from the excited complex using the overlap with ε (λ) λ ⁴ (near the maximum value A) Ir
To (tBuppm) ₃ and then to the PL spectrum of Ir (tBuppm) ₃ and [Ir (d)
mdppr-P) ₂ (divm)] overlaps with ε (λ) λ ⁴ (maximum value C to 650 nm)
(Nearby) using Ir (tBuppm) ₃ to [Ir (dmdppr-P) ₂ (divm)
], It can be seen that energy transfer is possible in stages. It should be noted that the energy can be directly transferred from the excited complex to the second phosphorescent compound [Ir (dmdppr-P) ₂ (divm)]. As can be seen from FIG. 49, this is [Ir (dmdppr-P) ₂
In the triplet MLCT absorption band (near the maximum value C) of [(divm)], ε (λ) λ ⁴ of [Ir (dmdppr-P) ₂ (divm)] overlaps with the PL spectrum F (λ) of the excited complex. Because it is.

The element characteristics of these light emitting elements were measured. The measurement was performed at room temperature (atmosphere maintained at 25 ° C.).

The luminance-current efficiency characteristics of the light emitting element 4 are shown in FIG. 35. Further, the voltage-luminance characteristic is shown in FIG. Further, the luminance-external quantum efficiency characteristics are shown in FIG. 37. In addition, the brightness-power efficiency characteristics are shown in FIG. 38.
Shown in.

As described above, it was found that the light emitting element 4 exhibits good element characteristics. In particular, FIGS. 35 and 3
7. As can be seen from FIG. 38, it has a very good luminous efficiency, and the external quantum efficiency is practical brightness (
A high value of 20% or more was shown in the vicinity of 1000 cd / m ² ). Similarly, the current efficiency is about 50 cd / A, and the power efficiency is about 50 lm / W, which are very good values.

Further, FIG. 39 shows an emission spectrum when a current of 0.1 mA is passed through the light emitting element 4. In FIG. 39, the horizontal axis represents wavelength (nm) and the vertical axis represents emission intensity (arbitrary unit). From FIG. 39
The light emitting element 4 is composed of light having a green wavelength derived from [Ir (tBuppm) ₂ (acac)] and [Ir (tBuppm) 2 (acac)].
It was found that the emission spectrum showed a well-balanced inclusion of light having a red wavelength derived from dmdppr-P) ₂ (divm)].

The luminance-current efficiency characteristics of the light emitting element 5 are shown in FIG. 40. Further, the voltage-luminance characteristic is shown in FIG. Further, the luminance-external quantum efficiency characteristics are shown in FIG. 42. In addition, the brightness-power efficiency characteristics are shown in FIG. 43.
Shown in.

As described above, it was found that the light emitting element 5 exhibits good element characteristics. In particular, FIGS. 40 and 4
2. As can be seen from FIG. 43, it has a very good luminous efficiency, and the external quantum efficiency is practical brightness (
At around 1000 cd / m ² ), it showed a high value of around 25%. Similarly, the current efficiency is about 65 cd / A, and the power efficiency is about 70 lm / W, which are very good values.

Further, FIG. 44 shows an emission spectrum when a current of 0.1 mA is passed through the light emitting element 5. In FIG. 44, the horizontal axis represents wavelength (nm) and the vertical axis represents emission intensity (arbitrary unit). From FIG. 44
The light emitting element 5 contains light having a green wavelength derived from [Ir (tBuppm) ₂ (acac)] and [Ir (tBuppm) 2 (acac)].
It was found that the emission spectrum showed a well-balanced inclusion of light having a red wavelength derived from dmdppr-P) ₂ (divm)].

As described above, it was found that the light emitting element 4 and the light emitting element 5 corresponding to one aspect of the present invention are light emitting elements having good luminous efficiency and obtaining light from two kinds of light emitting center substances in a well-balanced manner. rice field.

(Reference example 1)
The organometallic complex used in the above embodiment, bis [2- (6-tert-butyl-4-pyrimidinyl-κN3) phenyl-κC] (2,4-pentanedionato-κ ² O, O') iridium ( III) (abbreviation: [Ir (tBuppm) ₂ (acac)]) synthesis example is shown. The structure of [Ir (tBuppm) ₂ (acac)] is shown below.

<Step 1; 4-tert-butyl-6-phenylpyrimidine (abbreviation: HtBuppm)
) Synthesis>
First, 22.5 g of 4,4-dimethyl-1-phenylpentane-1,3-dione and 50 g of formamide were placed in an eggplant flask equipped with a reflux tube, and the inside was replaced with nitrogen. The reaction solution was refluxed for 5 hours by heating the reaction vessel. Then, this solution was poured into an aqueous solution of sodium hydroxide, and the organic layer was extracted with dichloromethane. The obtained organic layer was washed with water and saturated brine, and dried over magnesium sulfate. The solution after drying was filtered. After distilling off the solvent of this solution, the obtained residue was purified by silica gel column chromatography using hexane: ethyl acetate = 10: 1 (volume ratio) as a developing solvent, and the pyrimidine derivative HtBupp was purified.
m was obtained (colorless oil, yield 14%). The synthesis scheme of step 1 is shown below.

<Step 2; Synthesis of di-μ-chloro-bis [bis (6-tert-butyl-4-phenylpyrimidinat) iridium (III)] (abbreviation: [Ir (tBuppm) ₂ Cl] ₂ )>
Next, 15 mL of 2-ethoxyethanol and 5 mL of water, HtBupp obtained in step 1 above.
1.49 g of m1.49 g and 1.04 g of iridium chloride hydrate (IrCl ₃・_H2O ) were placed in an eggplant flask equipped with a reflux tube, and the inside of the flask was replaced with argon. Then microwave (2.4
It was irradiated with 5 GHz (100 W) for 1 hour and reacted. After distilling off the solvent, the obtained residue was suction-filtered and washed with ethanol to obtain a dinuclear complex [Ir (tBuppm) ₂ Cl] ₂ (yellow-green powder, yield 73%). The synthesis scheme of step 2 is shown below.

<Step 3; Synthesis of (Acetylacetonato) bis (6-tert-butyl-4-phenylpyrimidinat) iridium (III) (abbreviation: [Ir (tBuppm) ₂ (acac)]>
Further, 40 mL of 2-ethoxyethanol, the dinuclear complex obtained in step 2 above [Ir (tB).
uppm) ₂ Cl] ₂ 1.61 g, acetylacetone 0.36 g, sodium carbonate 1.
27 g was placed in an eggplant flask equipped with a reflux tube, and the inside of the flask was replaced with argon. Then, microwave (2.45 GHz 120 W) was irradiated for 60 minutes to react. The solvent was distilled off, and the obtained residue was suction-filtered with ethanol and washed with water and ethanol. This solid is dissolved in dichloromethane, and Celite (Wako Pure Chemical Industries, Ltd., Catalog No .: 531-1)
6855), alumina, and celite were laminated in this order and filtered through a filtration aid. By recrystallizing the solid obtained by distilling off the solvent with a mixed solvent of dichloromethane and hexane,
The desired product was obtained as a yellow powder (yield 68%). The synthesis scheme of step 3 is shown below.

The analysis results of the yellow powder obtained in step 3 by nuclear magnetic resonance spectroscopy ( ¹ H NMR) are shown below. From this result, it was found that the organometallic complex Ir (tBuppm) ₂ (acac) was obtained.

^{1 1} H NMR. δ (CDCl ₃ ): 1.50 (s, 18H), 1.79 (s, 6H),
5.26 (s, 1H), 6.33 (d, 2H), 6.77 (t, 2H), 6.85 (t,
2H), 7.70 (d, 2H), 7.76 (s, 2H), 9.02 (s, 2H).

(Reference example 2)
In this reference example, the organometallic iridium complex used in the examples, bis {4,6-dimethyl-2.
-[3- (3,5-Dimethylphenyl) -5-Phenyl-2-pyrazinyl-κN] phenyl-κC} (2,6-dimethyl-3,5-heptandionato-κ ² O, O'') Iridium ( III) (Abbreviation: [Ir (dmdppr-P) ₂ (divm)]) will be described. The structure of [Ir (dmdppr-P) ₂ (divm)] (abbreviation) is shown below.

<Step 1: 2,3-bis (3,5-dimethylphenyl) pyrazine (abbreviation: Hdmdp)
synthesis of pr)>
First, 5.00 g of 2,3-dichloropyrazine and 3,5-dimethylphenylboronic acid 10
.. 23 g, sodium carbonate 7.19 g, bis (triphenylphosphine) palladium (I)
I) 0.29 g of dichloride (abbreviation: Pd (PPh ₃ ) ₂ Cl ₂ ), 20 mL of water and 20 mL of acetonitrile were placed in an eggplant flask equipped with a reflux tube, and the inside was replaced with argon. The reaction vessel was heated by irradiating it with microwaves (2.45 GHz 100 W) for 60 minutes. Here, an additional 2.55 g of 3,5-dimethylphenylboronic acid and 1.80 g of sodium carbonate
, Pd (PPh ₃ ) ₂ Cl ₂ 0.070 g, 5 mL of water and 5 mL of acetonitrile were placed in a flask and heated by irradiating with microwaves (2.45 GHz 100 W) again for 60 minutes.

Then, water was added to this solution, and the organic layer was extracted with dichloromethane. The obtained organic layer was washed with saturated aqueous sodium hydrogen carbonate solution, water and saturated brine, and dried over magnesium sulfate. The solution after drying was filtered. After distilling off the solvent of this solution, the obtained residue was purified by flash column chromatography using hexane: ethyl acetate = 5: 1 (volume ratio) as a developing solvent. The solvent was distilled off, and the obtained solid was divided into dichloromethane: ethyl acetate = 10 :.
Purification was performed by flash column chromatography using 1 (volume ratio) as a developing solvent to obtain the desired pyrazine derivative Hdmdppr (abbreviation) (white powder, yield 44%). A microwave synthesizer (Discover manufactured by CEM) was used for microwave irradiation. The synthesis scheme of step 1 is shown in (a-1) below.

<Step 2: Synthesis of 2,3-bis (3,5-dimethylphenyl) -5-phenylpyrazine (abbreviation: Hdmdmpr-P)>
First, Hdmdppr (abbreviation) 4.28 g and dryTHF80 m obtained in step 1 above.
L was placed in a three-necked flask and the inside was replaced with nitrogen. After cooling the flask with ice, phenyllithium (
9.5 mL of (1.9 M butyl ether solution) was added dropwise, and the mixture was stirred at room temperature for 23 and a half hours. The reaction solution was poured into water and extracted with chloroform. The obtained organic layer was washed with water and saturated brine, and dried over magnesium sulfate. Manganese oxide was added to the obtained mixture, and the mixture was stirred for 30 minutes. Then, the solution was filtered and the solvent was distilled off. The obtained residue was purified by silica gel column chromatography using dichloromethane as a developing solvent, and the desired pyrazine derivative Hdmdppr was purified.
-P (abbreviation) was obtained (orange oil, yield 26%). The synthesis scheme of step 2 is as follows (a)
-2) is shown.

<Step 3: Di-μ-chloro-tetrakis {4,6-dimethyl-2- [3- (3,5-)
Synthesis of dimethylphenyl) -5-phenyl-2-pyrazinyl-κN] phenyl-κC} diiridium (III) (abbreviation: [Ir (dmdppr-P) ₂ Cl] ₂ )>
Next, 15 mL of 2-ethoxyethanol and 5 mL of water, Hdmdp obtained in step 2 above.
pr-P (abbreviation) 1.40 g, iridium chloride hydrate (IrCl ₃ · H ₂ O) (Sigma)
0.51 g (manufactured by a-Aldrich) was placed in an eggplant flask equipped with a reflux tube, and the inside of the flask was replaced with argon. Then, microwave (2.45 GHz 100 W) was irradiated for 1 hour to react. After distilling off the solvent, the obtained residue was suction-filtered and washed with ethanol to obtain a dinuclear complex [Ir (dmdppr-P) ₂ Cl] ₂ (abbreviation) (reddish brown powder, yield 58%).
). The synthesis scheme of step 3 is shown in (a-3) below.

<Step 4: Bis {4,6-dimethyl-2- [3- (3,5-dimethylphenyl) -5
-Phenyl-2-pyrazinyl-κN] Phenyl-κC} (2,6-dimethyl-3,5-heptandionat-κ ² O, O'') Iridium (III) (abbreviation: [Ir (dmdppr)
-P) ₂ (divm)] synthesis>
Further, 30 mL of 2-ethoxyethanol, the dinuclear complex obtained in step 3 above [Ir (d).
mdppr-P) ₂ Cl] ₂ 0.94 g, diisobutyryl methane (abbreviation: Hdivm)
0.23 g and 0.52 g of sodium carbonate were placed in an eggplant flask equipped with a reflux tube, and the inside of the flask was replaced with argon. Then, it was heated by irradiating with microwave (2.45 GHz 120 W) for 60 minutes. The solvent was distilled off, and the obtained residue was suction filtered with ethanol. The obtained solid was washed with water and ethanol and recrystallized from a mixed solvent of dichloromethane and ethanol to recrystallize the organic metal complex of the present invention [Ir (dmdppr-P) ₂ (divm)].
(Abbreviation) was obtained as a dark red powder (yield 75%). The synthesis scheme of step 4 is as follows (a)
-4).

The analysis results of the dark red powder obtained by the above synthesis method by nuclear magnetic resonance spectroscopy ( ¹ H-NMR) are shown below. From this result, in this synthetic example, the organometallic complex [Ir (dmdp)
It was found that pr-P) ₂ (divm)] (abbreviation) was obtained.

^{1 1} H-NMR. δ (CDCl ₃ ): 0.79 (d, 6H), 0.96 (d, 6H), 1
.. 41 (s, 6H), 1.96 (s, 6H), 2.24-2.28 (m, 2H), 2.4
1 (s, 12H), 5.08 (s, 1H), 6.46 (s, 2H), 6.82 (s, 2H)
), 7.18 (s, 2H), 7.39-7.50 (m, 10H), 8.03 (d, 4H)
, 8.76 (s, 2H).

10 Electrode 11 Electrode 101 First electrode 102 Second electrode 103 EL layer 111 Hole injection layer 112 Hole transport layer 113 Light emitting layer 113a First light emitting layer 113 Da First phosphorescent compound 113Ha First host material 113b Second light emitting layer 113Db Second phosphorescent compound 113Hb Second host material 113A First organic compound 113Ec Excitation complex 114 Electron transport layer 115 Electron injection layer 400 Substrate 401 First electrode 402 Auxiliary electrode 403 EL layer 404 Second electrode 405 Sealing material 406 Sealing material 407 Encapsulating substrate 412 Pad 420 IC chip 601 Drive circuit section (source line drive circuit)
602 Pixel unit 603 Drive circuit unit (gate line drive circuit)
604 Sealing board 605 Sealing material 607 Space 608 Wiring 609 FPC (Flexible printed circuit)
610 Device board 611 Switching TFT
612 Current control TFT
613 First electrode 614 Insulation 616 EL layer 617 Second electrode 618 Light emitting element 623 n-channel TFT
624 p-channel TFT
625 Drying material 901 Housing 902 Liquid crystal layer 903 Backlight unit 904 Housing 905 Driver IC
906 Terminal 951 Substrate 952 Electrode 953 Insulation layer 954 Partition layer 955 EL layer 956 Electrode 1001 Substrate 1002 Underground insulating film 1003 Gate insulating film 1006 Gate electrode 1007 Gate electrode 1008 Gate electrode 1020 First interlayer insulating film 1021 Second interlayer insulating film 1022 Electrode 1024W First electrode of the light emitting element 1024R First electrode of the light emitting element 1024G First electrode of the light emitting element 1024B First electrode of the light emitting element 1025 Partition 1028 EL layer 1029 Second electrode 1031 of the light emitting element Substrate 1032 Sealing material 1033 Transparent base material 1034R Red colored layer 1034G Green colored layer 1034B Blue colored layer 1035 Black layer (black matrix)
1036 Overcoat layer 1037 Third interlayer insulating film 1040 Pixel part 1041 Drive circuit part 1042 Peripheral part 1044W White light emitting area 1044R Red light emitting area 1044B Blue light emitting area 1044G Green light emitting area 2001 Housing 2002 Light source 3001 Lighting device 3002 Display device 5000 Display 5001 Display 5002 Display 5003 Display 5004 Display 5005 Display 7101 Housing 7103 Display 7105 Stand 7107 Display 7109 Operation key 7110 Remote control operation machine 7201 Main unit 7202 Housing 7203 Display 7204 Keyboard 7205 External connection port 7206 Pointing device 7210 Second display unit 7301 Housing 7302 Housing 7303 Connecting unit 7304 Display unit 7305 Display unit 7306 Speaker unit 7307 Recording medium insertion unit 7308 LED lamp 7309 Operation key 7310 Connection terminal 7311 Sensor 7400 Mobile phone 7401 Housing 7402 Display unit 7403 Operation Button 7404 External connection port 7405 Speaker 7406 Mike 9033 Fastener 9034 Switch 9035 Power switch 9036 Switch 9038 Operation switch 9630 Housing 9631 Display 9631a Display 9631b Display 9632a Touch panel area 9632b Touch panel area 9633 Solar battery 9634 Charge / discharge control circuit 9635 Battery 9636 DCDC converter 9637 operation key 9638 converter 9339 button

Claims (1)

A second light emitting layer in which the first phosphorescent compound is dispersed in the first host material between the pair of electrodes, and a second light emitting layer having a longer wavelength than that of the first phosphorescent compound. The phosphorescent compound comprises a second light emitting layer dispersed in a second host material.
The wavelength of the maximum value located on the longest wavelength side of the function represented by ε (λ) λ ⁴ of the second phosphorescent compound is the phosphorescence emission spectrum F (λ) of the first phosphorescent compound. A light emitting element that overlaps with. (However, ε (λ) represents the molar extinction coefficient of each phosphorescent compound and is a function of the wavelength λ.)

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