JP2024007357A - Light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a green phosphorescent light-emitting device having a long service life.

SOLUTION: The light-emitting device includes a first electrode, a second electrode, and a light-emitting layer. The light-emitting layer is positioned between the first electrode and the second electrode. The light-emitting layer comprises a first organic compound, a second organic compound, and a phosphorescent material. The first organic compound has a heteroaromatic ring skeleton and an aromatic hydrocarbon group. The second organic compound has a bicarbazole skeleton. The lowest triplet excitation level of the first organic compound is derived only from the aromatic hydrocarbon group. The energy of the lowest triplet excitation level of the second organic compound is 2.20 eV or more and 2.65 eV or less.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

One aspect of the present invention relates to a light emitting device.

Note that one embodiment of the present invention is not limited to the above technical field. The technical fields of one embodiment of the present invention include semiconductor devices, display devices, light-emitting devices, power storage devices, storage devices, electronic devices, lighting devices, input devices (for example, touch sensors), input/output devices (for example, touch panels), An example of such a driving method or a manufacturing method thereof can be mentioned.

In recent years, display devices are expected to be applied to various uses. For example, applications of large display devices include home television devices (also referred to as televisions or television receivers), digital signage (digital signage), PID (Public Information Display), etc. . Further, as mobile information terminals, smartphones and tablet terminals equipped with touch panels are being developed.

At the same time, there is also a demand for higher definition display devices. Examples of devices that require high-definition display devices include virtual reality (VR), augmented reality (AR), substitute reality (SR), and mixed reality (MR). ), and high-definition display devices for use in these devices are being actively developed.

Light emitting devices using organic compounds are being actively researched as display devices suitable for such high-definition display devices. Light-emitting devices (also referred to as organic EL devices or organic EL elements) that utilize the electroluminescence (hereinafter referred to as EL) phenomenon of organic compounds can be easily made thin and lightweight, and can respond quickly to input signals. It has characteristics such as being able to be driven using a DC constant voltage power supply, and is applied to display devices.

Displays and lighting devices using such light-emitting devices are suitable for various electronic devices, but research and development is progressing in search of light-emitting devices with better characteristics.

In particular, the lifespan of a light emitting device is an important characteristic that relates to the usage period, display quality, and power consumption of the electronic device. Patent Document 1 discloses a configuration in which the luminous efficiency, lifetime, and driving voltage of a phosphorescent device can be improved by using an exciplex as an energy donor.

Japanese Patent Application Publication No. 2012-186461

Nicholas J. Turro, V. Ramamurthy, J. C. Scaiano, “MODERN MOLECULAR PHOTOCHEMISTRY OF ORGANIC MOLECULES”, UNIVERSITY SCIENCE BOOKS, February 10, 2010, pp. 204-208 Daisaku TANAKA et al., “Ultra High Efficiency Green Organic Light-Emitting Devices”, Japanese Journal of Applied Physics, Vol. 46, No. 1, 2007, pp. L10-L12

An object of one embodiment of the present invention is to provide a highly reliable light-emitting device. Another object of one embodiment of the present invention is to provide a light-emitting device that emits light efficiently and has good reliability. Another object of one embodiment of the present invention is to provide a green phosphorescent device with good reliability. Another object of one embodiment of the present invention is to provide a green phosphorescent device that emits light efficiently and has good reliability.

Another object of one embodiment of the present invention is to provide a highly reliable display device. Another object of one embodiment of the present invention is to provide a display device with low power consumption and high reliability.

Alternatively, the present invention aims to provide a new organic compound, a new light emitting device, a new display device, a new display module, and a new electronic device.

Note that the description of these issues does not preclude the existence of other issues. One embodiment of the present invention does not necessarily need to solve all of these problems. Problems other than these can be extracted from the description, drawings, and claims.

One embodiment of the present invention includes a first electrode, a second electrode, and a light emitting layer, and the light emitting layer is located between the first electrode and the second electrode. , the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent substance, and the first organic compound includes a heteroaromatic ring skeleton and an aromatic hydrocarbon group. and the second organic compound has a bicarbazole skeleton, the lowest triplet excited state of the first organic compound is localized in the aromatic hydrocarbon group, and the lowest triplet excited state of the second organic compound is localized in the aromatic hydrocarbon group. The light emitting device has a triplet excited level energy of 2.20 eV or more and 2.65 eV or less.

Another aspect of the present invention includes a first electrode, a second electrode, and a light-emitting layer, and the light-emitting layer is connected to the first electrode and the second electrode. The light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent substance, and the first organic compound has a heteroaromatic ring skeleton, a substituent, and a phosphorescent substance. , the substituent has a 1,1':4',1''-terphenyl skeleton, the second organic compound has a bicarbazole skeleton, and the second organic compound has a 1,1':4',1''-terphenyl skeleton; The light emitting device is a light emitting device in which the energy of the lowest triplet excited level is 2.20 eV or more and 2.65 eV or less.

Alternatively, another embodiment of the present invention is a light emitting device having the above structure, in which the substituent includes one or both of a dibenzofuran skeleton and a dibenzothiophene skeleton.

Alternatively, another embodiment of the present invention is a light emitting device having the above structure, wherein the substituent is substituted on the heteroaromatic ring skeleton at the meta position.

Another aspect of the present invention is a light emitting device having the above structure, wherein the substituent is substituted on the heteroaromatic ring skeleton via a 1,3-phenylene group.

Alternatively, another embodiment of the present invention includes a first electrode, a second electrode, and a light-emitting layer, and the light-emitting layer is connected to the first electrode and the second electrode. located between, the light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent substance, and the first organic compound has a heteroaromatic ring skeleton and a 1,1 ':4',1''-terphenyl group, the second organic compound has a bicarbazole skeleton, and the energy of the lowest triplet excited level of the second organic compound is 2 It is a light emitting device with a voltage of .20 eV or more and 2.65 eV or less.

Another aspect of the present invention is a light emitting device having the above structure, wherein the 1,1':4',1''-terphenyl group is substituted at the meta position on the heteroaromatic ring skeleton.

Alternatively, in another aspect of the present invention, in the above structure, the 1,1':4',1''-terphenyl group is substituted with the heteroaromatic ring skeleton via a 1,3-phenylene group. It is a device.

Alternatively, another embodiment of the present invention is a light emitting device having the above structure, in which the heteroaromatic ring skeleton includes a condensed ring.

Alternatively, another aspect of the present invention is a light emitting device having the above structure, in which the heteroaromatic ring skeleton includes a diazine skeleton.

Alternatively, another aspect of the present invention is a light emitting device having the above structure, in which the heteroaromatic ring skeleton includes a condensed ring and a diazine skeleton.

Alternatively, another aspect of the present invention is a light emitting device having the above structure, in which the heteroaromatic ring skeleton has a benzofuropyrimidine skeleton or a triazine skeleton.

Alternatively, another embodiment of the present invention is a light emitting device in which the second organic compound has a naphthyl group in the above structure.

Alternatively, another aspect of the present invention is a light emitting device having the above structure, in which the lowest triplet excitation level of the first organic compound originates only from the substituent.

Alternatively, another embodiment of the present invention is a display module including the above light-emitting device and at least one of a connector and an integrated circuit.

Alternatively, another embodiment of the present invention is an electronic device including the above-described light-emitting device and at least one of a housing, a battery, a camera, a speaker, and a microphone.

In one embodiment of the present invention, a highly reliable light-emitting device can be provided. Further, in one embodiment of the present invention, a light-emitting device that emits light efficiently and has good reliability can be provided. Further, in one embodiment of the present invention, a highly reliable green phosphorescent device can be provided. Further, in one embodiment of the present invention, a green phosphorescent device that emits light efficiently and has good reliability can be provided.

Further, one embodiment of the present invention can provide a highly reliable display device. Further, in one embodiment of the present invention, a display device with low power consumption and high reliability can be provided.

Alternatively, a new organic compound, a new light emitting device, a new display device, a new display module, and a new electronic device can be provided.

Note that the description of these effects does not preclude the existence of other effects. One embodiment of the present invention does not necessarily need to have all of these effects. Effects other than these can be extracted from the description, drawings, and claims.

1(A) to FIG. 1(C) are schematic diagrams of a light-emitting device of one embodiment of the present invention. FIGS. 2A and 2B are diagrams illustrating a display device of one embodiment of the present invention. FIGS. 3A and 3B are diagrams illustrating a display device of one embodiment of the present invention. FIGS. 4A to 4E are cross-sectional views illustrating an example of a method for manufacturing a display device. FIGS. 5A to 5D are cross-sectional views illustrating an example of a method for manufacturing a display device. FIGS. 6A to 6D are cross-sectional views illustrating an example of a method for manufacturing a display device. FIGS. 7A to 7C are cross-sectional views illustrating an example of a method for manufacturing a display device. FIGS. 8A to 8C are cross-sectional views illustrating an example of a method for manufacturing a display device. FIGS. 9A to 9C are cross-sectional views illustrating an example of a method for manufacturing a display device. FIG. 10(A) and FIG. 10(B) are perspective views showing a configuration example of a display module. FIG. 11(A) and FIG. 11(B) are cross-sectional views showing a configuration example of a display device. FIG. 12 is a perspective view showing a configuration example of a display device. FIG. 13 is a cross-sectional view showing a configuration example of a display device. FIG. 14 is a cross-sectional view showing a configuration example of a display device. FIG. 15 is a cross-sectional view showing a configuration example of a display device. FIG. 16(A) to FIG. 16(D) are diagrams showing an example of an electronic device. FIG. 17(A) to FIG. 17(F) are diagrams showing an example of an electronic device. FIG. 18(A) to FIG. 18(G) are diagrams illustrating an example of an electronic device. FIG. 19 is a diagram showing the luminance-current density characteristics of Light-emitting Device 1 and Comparative Light-emitting Device 1. FIG. 20 is a diagram showing the current efficiency-luminance characteristics of Light-emitting Device 1 and Comparative Light-emitting Device 1. FIG. 21 is a diagram showing the brightness-voltage characteristics of Light-emitting Device 1 and Comparative Light-emitting Device 1. FIG. 22 is a diagram showing the current density-voltage characteristics of Light-emitting Device 1 and Comparative Light-emitting Device 1. FIG. 23 is a diagram showing the emission spectra of Light Emitting Device 1 and Comparative Light Emitting Device 1. FIG. 24 is a diagram showing normalized luminance-time change characteristics of Light-emitting Device 1 and Comparative Light-emitting Device 1. FIG. 25(A) to FIG. 25(C) are diagrams showing the analysis results based on the calculation of 8mpTP-4mDBtPBfpm. FIG. 26(A) to FIG. 26(C) are diagrams showing the results of calculation analysis of the organic compound represented by structural formula (216). FIG. 27(A) to FIG. 27(C) are diagrams showing analysis results based on calculation of 8BP-4mDBtPBfpm. FIG. 28 is a diagram showing the brightness-current density characteristics of Light-emitting Device 2 and Comparative Light-emitting Device 2. FIG. 29 is a diagram showing current efficiency-luminance characteristics of Light-emitting Device 2 and Comparative Light-emitting Device 2. FIG. 30 is a diagram showing the brightness-voltage characteristics of Light-emitting Device 2 and Comparative Light-emitting Device 2. FIG. 31 is a diagram showing current density-voltage characteristics of Light-emitting Device 2 and Comparative Light-emitting Device 2. FIG. 32 is a diagram showing the emission spectra of Light Emitting Device 2 and Comparative Light Emitting Device 2. FIG. 33 is a diagram showing normalized luminance-time change characteristics of Light-emitting Device 2 and Comparative Light-emitting Device 2. FIG. 34 is a diagram showing the brightness-current density characteristics of the light-emitting device 3 and the light-emitting device 4. FIG. 35 is a diagram showing current efficiency-luminance characteristics of light-emitting device 3 and light-emitting device 4. FIG. 36 is a diagram showing the brightness-voltage characteristics of light-emitting device 3 and light-emitting device 4. FIG. 37 is a diagram showing current density-voltage characteristics of light-emitting device 3 and light-emitting device 4. FIG. 38 is a diagram showing the emission spectra of light emitting device 3 and light emitting device 4. FIG. 39 is a diagram showing the normalized luminance-time change characteristics of the light-emitting device 3 and the light-emitting device 4. FIG. 40 is a diagram showing the measurement results of the emission spectra of 8mpTP-4mDBtPBfpm and 8mpTP-4mDBtPBfpm-d ₂₃ at low temperatures. FIG. 41 is a diagram showing the measurement results of the luminescence lifetimes of 8mpTP-4mDBtPBfpm and 8mpTP-4mDBtPBfpm-d ₂₃ at low temperatures. FIG. 42 is a diagram showing the current efficiency-luminance characteristics of the light-emitting devices 5 to 7. FIG. 43 is a diagram showing the brightness-voltage characteristics of the light-emitting devices 5 to 7. FIG. 44 is a diagram showing the current efficiency-current density characteristics of the light-emitting devices 5 to 7. FIG. 45 is a diagram showing current density-voltage characteristics of light-emitting devices 5 to 7. FIG. 46 is a diagram showing the brightness-current density characteristics of the light-emitting devices 5 to 7. FIG. 47 is a diagram showing electroluminescence spectra of light emitting devices 5 to 7. FIG. 48 is a diagram showing the normalized luminance-time change characteristics of the light-emitting devices 5 to 7.

Embodiments will be described in detail using the drawings. However, those skilled in the art will easily understand that the present invention is not limited to the following description, and that the form and details thereof can be changed in various ways without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the contents described in the embodiments shown below.

Note that in this specification and the like, a device manufactured using a metal mask or an FMM (fine metal mask, high-definition metal mask) is sometimes referred to as a device with an MM (metal mask) structure. Further, in this specification and the like, a device manufactured without using a metal mask or FMM may be referred to as a device with an MML (metal maskless) structure.

(Embodiment 1)
Phosphorescent devices basically emit light from the lowest triplet excited level (T1 level), which is located at a lower energy level than the lowest singlet excited level ( _S1 level), so they emit light of _the same color. The energy gap between the highest occupied molecular orbital (HOMO) level and the lowest unoccupied molecular orbital (LUMO) level (HOMO-LUMO energy gap) ) of It is necessary to use a wide range of materials.

Further, when the exciplex has a configuration in which a phosphorescent material is excited by using an exciplex as an energy donor (Exciplex-Triplet Energy Transfer), the S ₁ level of the exciplex is equal to or higher than the T ₁ level of the phosphorescent material. This is preferable (the S ₁ level and the T ₁ level in the exciplex are close to each other). Further, it is preferable that the T ₁ level of each of the plurality of compounds forming the exciplex is equal to or higher than the T ₁ level of the phosphorescent substance.

The exciplex for providing energy to the phosphorescent material in a light emitting device having an ExTET configuration is preferably formed from an organic compound having an electron transporting property and an organic compound having a hole transporting property. In this case, the HOMO-LUMO energy gap of the exciplex corresponds to the energy gap between the LUMO level of an organic compound having an electron transporting property and the HOMO level of an organic compound having a hole transporting property.

In this case, in an organic compound having an electron transporting property and an organic compound having a hole transporting property that form an exciplex, the HOMO level of the organic compound having an electron transporting property is the HOMO level of the organic compound having a hole transporting property. The LUMO level of an organic compound having a hole transporting property is lower than that of an organic compound having an electron transporting property. Therefore, the HOMO-LUMO energy gap of each of the organic compound having an electron transporting property and the organic compound having a hole transporting property forming an exciplex is inevitably larger than the HOMO-LUMO energy gap of the exciplex.

Here, the generation of an exciplex in a light-emitting device is a process in which an anion of an organic compound with an electron transporting property and a cation of an organic compound with a hole transporting property are adjacent to form an exciplex directly (electroplex process). ) is considered to be dominant. In addition, even if one of the organic compounds with electron-transporting properties and the organic compounds with hole-transporting properties becomes excited, they will quickly interact with the other to form an exciplex. It is said that most of them exist as exciplexes, and no attention has been paid to the S ₁ level and T ₁ level of the organic compound itself that forms the exciplex.

However, the present inventors found that when forming a light emitting layer using an organic compound having an electron transporting property and an organic compound having a hole transporting property and having a specific structure, each triplet excitation energy is We found that it affects sexuality. This is considered to be because there can be a process in the device in which each T ₁ level is generated from the T ₁ level of the exciplex.

Regarding the S ₁ level or T ₁ level of organic compounds, the ν = 0 → ν = 0 transition (0 → 0 band) between the vibrational levels of the ground state and the excited state is clearly observed in the fluorescence spectrum or phosphorescence spectrum. When observed, it is preferable to calculate using the 0→0 band (for example, see Non-Patent Document 1). If the 0→0 band is not clear, draw a tangent at the value where the slope of the peak on the short wavelength side of the fluorescence spectrum is maximum, and calculate the energy of the wavelength at the intersection of the tangent with the horizontal axis (wavelength) or the baseline. Take the _S1 level, draw a tangent at the value where the slope of the peak on the short wavelength side in the phosphorescence spectrum is maximum, and calculate the energy at the wavelength of the intersection of the tangent with the horizontal axis (wavelength) or the baseline as the _T1 level. (For example, see Non-Patent Document 2). In this specification, each level is measured by the latter method. Furthermore, when comparing levels, the levels calculated using the same method should be compared.

A light-emitting device of one embodiment of the present invention includes a light-emitting layer 113 at least between the first electrode 101 and the second electrode 102, as shown in FIG. The light emitting layer 113 includes a phosphorescent material, a first organic compound, and a second organic compound.

The first organic compound is an organic compound having electron transport properties. Further, the first organic compound has a heteroaromatic ring skeleton and a first substituent that is substituted on the heteroaromatic ring skeleton. In one aspect of the present invention, the first organic compound has a lowest triplet excited state localized in the first substituent, and a lowest triplet excited level ( _T1 level) in the first substituent. It is an organic compound derived from That is, this means that among the skeletons or groups constituting the first organic compound, the one with the lowest T ₁ level is the first substituent. In other words, it can be said that the lowest triplet excited state T ₁ (that is, triplet excitons) of the first organic compound is distributed (or localized) in the first substituent.

The heteroaromatic ring skeleton in the first organic compound is preferably a π-electron deficient heteroaromatic ring skeleton having two or more nitrogen atoms. In particular, the heteroaromatic ring skeleton preferably includes a diazine skeleton or a triazine skeleton, and particularly preferably a diazine skeleton.

Further, the heteroaromatic ring skeleton preferably includes a condensed ring, and when a hydrocarbon such as a benzene ring is condensed to the heteroaromatic ring, the condensed ring is included in the heteroaromatic ring. That is, both a monocyclic heteroaromatic ring (eg, triazine ring) and a condensed heteroaromatic ring (eg, quinoxaline ring, benzofuropyrimidine ring) in which a benzene ring or the like is condensed are considered to be one heteroaromatic ring. It is particularly preferable that the heteroaromatic ring skeleton includes a benzofuropyrimidine skeleton or a benzothienopyrimidine skeleton.

Specifically, the heteroaromatic ring skeleton in the first organic compound is preferably a skeleton represented by the following structural formulas (B-1) to (B-32).

The first substituent in the first organic compound is preferably an aromatic hydrocarbon group or a heteroaromatic ring group. However, the first substituent has at least a 1,1':4',1''-terphenyl skeleton, and the 1,1':4',1''-terphenyl skeleton terminates in benzene. At the meta-position or ortho-position of the ring, that is, at the 3-position or 2-position, or when the 1,1':4',1''-terphenyl skeleton is mediated by a 1,3-phenylene group or a 1,2-phenylene group. is a group bonded to the above-mentioned heteroaromatic ring skeleton.

In addition, in the above-mentioned 1,1':4',1''-terphenyl skeleton, among the three benzene rings that are bonded to each other at the para position, in two adjacent benzene rings, the carbon next to the bonded carbon is They may be crosslinked with each other by oxygen, sulfur, or carbon. That is, the first substituent may have a dibenzothiophene skeleton, a dibenzofuran skeleton, or a fluorene skeleton, and the 1,1':4',1''-terphenyl skeleton may have a dibenzothiophene skeleton, a dibenzofuran skeleton, or a dibenzofuran skeleton. Alternatively, it is preferable that a fluorene skeleton is included.

Further, the 1,1':4',1''-terphenyl skeleton in the first substituent may have a substituent. Examples of the substituent include an alkyl group having 1 to 6 carbon atoms and a phenyl group.

Specifically, the first substituent in the first organic compound is preferably a skeleton represented by the following structural formulas (S1-1) to (S1-24).

In addition, when the above-mentioned heteroaromatic ring skeleton has a condensed ring and a ring composed only of carbon exists in a part of the condensed ring, the first substituent is a ring composed only of the carbon. It is preferable that it be replaced with .

Moreover, it is preferable that the first organic compound has one or two second substituents having hole transporting properties in addition to the above-mentioned heteroaromatic ring skeleton and first substituent.

The second substituent is preferably a group represented by the following general formulas (Ht-1) to (Ht-15).

In addition, in the above general formulas (Ht-1) to (Ht-15), Q represents oxygen or sulfur. Further, Ar ¹⁰ represents a substituted or unsubstituted aryl group having 6 to 13 carbon atoms.

Further, the second substituent is preferably bonded to the heteroaromatic ring skeleton via a phenylene group. In this case, the phenylene group is preferably a 1,3-phenylene group or a 1,2-phenylene group, more preferably a 1,3-phenylene group.

In addition, when the above-mentioned heteroaromatic ring skeleton has a condensed ring and a ring composed only of carbon exists in a part of the condensed ring, a second substituent or a phenylene to which a second substituent is bonded The group is preferably substituted on a ring containing a hetero atom (particularly a ring containing nitrogen, such as a diazine ring).

Note that in the first organic compound, part or all of the hydrogen contained in the first organic compound may be deuterium.

As the above first organic compound, specifically, organic compounds represented by the following structural formulas (200) to (225) are preferable.

Note that the first organic compound may further have a substituent instead of hydrogen or deuterium. The substituent is preferably an alkyl group having 1 to 6 carbon atoms or a phenyl group.

The second organic compound is an organic compound having hole transport properties. The second organic compound has a bicarbazole skeleton and has a T ₁ level of 2.20 eV or more and 2.65 eV or less, preferably 2.50 eV or more and 2.60 eV or less.

As mentioned above, the second organic compound is an organic compound having a bicarbazole skeleton, particularly a 3,3'-bicarbazole skeleton, especially 9,9'-diaryl-9H,9'H-3,3' - An organic compound having a bicarbazole skeleton is preferable. However, the second organic compound is an organic compound having a T ₁ level of 2.20 eV or more and 2.65 eV or less, preferably 2.50 eV or more and 2.60 eV or less. The T ₁ level of 9,9'-diphenyl-9H,9'H-3,3'-bicarbazole (PCCP) is 2.73 eV, but 9,9'-diaryl-9H,9' similar to PCCP By lowering the T ₁ level compared to PCCP while maintaining the H-3,3'-bicarbazole skeleton, the light-emitting device of one embodiment of the present invention can have a long lifetime. However, in consideration of exciting green to yellow phosphorescent materials, the T ₁ level is preferably 2.20 eV or higher.

The second organic compound preferably has an aromatic hydrocarbon group, especially a naphthyl group. The naphthyl group is preferably bonded to the nitrogen at the 9-position of at least one of the two carbazole skeletons. Moreover, it is preferable that the lowest triplet excited level of the second organic compound originates from the aromatic hydrocarbon group.

Alternatively, the second organic compound preferably has a 1,1':4',1''-terphenyl skeleton. Examples of the second organic compound having such a structure include an organic compound having a phenyl group at the 7-position of the carbazole skeleton, such as the organic compound shown by the following structural formula (304), and the following structural formula (303). Examples include organic compounds having a parabiphenyl group at the 6-position of the carbazole skeleton, such as the organic compounds shown in . Further, the lowest triplet excited level of the second organic compound is preferably derived from the 1,1':4',1''-terphenyl skeleton.

As the second organic compound, it is possible to use, for example, organic compounds represented by the following structural formulas (300) to (305).

Note that the first organic compound and the second organic compound are preferably a combination capable of forming an exciplex capable of exciting the above-mentioned phosphorescent substance. When the exciplex of the first organic compound and the second organic compound becomes an energy donor for the phosphorescent substance, effects such as improved energy transfer efficiency and reduced driving voltage can be obtained.

At this time, the S ₁ level of the exciplex is higher than the T ₁ level of the above-mentioned phosphorescent substance (the S ₁ level and the T ₁ level of the exciplex are close to each other). Note that the difference between the S ₁ level of the exciplex and the T ₁ level of the above-mentioned phosphorescent material is preferably 0.20 eV or less in order to reduce the driving voltage.

As the phosphorescent material, a yellow to green phosphorescent material that emits light at 470 nm to 560 nm can be used. Any known material may be used as long as it exhibits such phosphorescence, but it is preferable to use, for example, the following organometallic complexes.

Tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm) ₃ ]), Tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation) :[Ir(tBuppm) ₃ ]), (acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm) ₂ (acac)]), (acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium(III) (acetylacetonato)bis[6-(2 _- norbornyl)] -4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(nbppm) ₂ (acac)]), (acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenyl pyrimidinato]iridium(III) (abbreviation: [Ir(mpmppm) ₂ (acac)]), (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm) Organometallic iridium complexes having a _pyrimidine skeleton such as -Me) ₂ (acac)]), (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-iPr) ₂ (acac) ), tris(2-phenylpyridinato-N,C ^2' )iridium(III) (abbreviation: [Ir(ppy) ₃ ]), bis(2-phenyl Pyridinato-N,C ^2' )iridium(III) acetylacetonate (abbreviation: [Ir(ppy) ₂ (acac)]), bis(benzo[h]quinolinato)iridium(III) acetylacetonate (abbreviation: [Ir(bzz) ₂ (acac)]), tris(benzo[h]quinolinato)iridium(III) (abbreviation: [Ir(bzz) ₃ ]), tris(2-phenylquinolinato-N,C ^2' ) Iridium(III) (abbreviation: [Ir(pq) ₃ ]), bis(2-phenylquinolinato-N,C ^2' )iridium(III) acetylacetonate (abbreviation: [Ir(pq) ₂ (acac)]) ), [2-d ₃ -methyl-8-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(5-d ₃ -methyl-2-pyridyl-κN2)phenyl -κ] Iridium(III) (abbreviation: [Ir(5mppy-d ₃ ) ₂ (mbfpypy-d ₃ )]), [2-d3-methyl-(2-pyridinyl-κN)benzofuro[2,3-b] Pyridine-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: [Ir(ppy) ₂ (mbfpypy-d ₃ )]), [2-(4-d ₃ - Methyl-5-phenyl-2-pyridinyl-κN2)phenyl-κC]bis[2-( ₅ -d 3 -methyl-2-pyridinyl-κN2)phenyl-κC]iridium(III) (abbreviation: [Ir(5mppy- d ₃ ) ₂ (mdppy-d3)]), [2-methyl-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(2-pyridinyl-κN)phenyl-κC ] Iridium(III) (abbreviation: [Ir(ppy) ₂ (mbfpypy)]), [2-(4-methyl-5-phenyl-2-pyridinyl-κN)phenyl-κC]bis[2-(2-pyridinyl) -κN)phenyl-κC]iridium (abbreviation: [Ir(ppy) ₂ (mdppy)]), as well as organometallic iridium complexes with a pyridine skeleton, such as tris(acetylacetonato)(monophenanthroline)terbium(III). (abbreviation: [Tb(acac) ₃ (Phen)]). These are compounds that mainly emit yellow to green phosphorescence, and have an emission peak in the wavelength range from 470 nm to 570 nm. Note that an organometallic iridium complex having a pyrimidine skeleton is particularly preferable because it has outstanding reliability and luminous efficiency. In addition, an organometallic iridium complex having a deuterium-substituted ligand is a preferable structure because it is particularly reliable when the first organic compound and the second organic compound are used together.

A light-emitting device of one embodiment of the present invention having such a structure can be a phosphorescent light-emitting device with a long life and good reliability.

Next, the configuration of the light emitting device will be explained in detail.

FIG. 1 is a schematic diagram of a light-emitting device according to one embodiment of the present invention. The light emitting device includes a first electrode 101 provided on an insulator 105, and an EL layer 103 between the first electrode 101 and the second electrode 102. The EL layer has at least a light emitting layer 113. Further, the first electrode is independent in each light emitting device, and the second electrode is formed as a layer shared by a plurality of light emitting devices.

In addition to this, the EL layer 103 has functional layers such as a hole injection layer 111, a hole transport layer 112, an electron transport layer 114, and an electron injection layer 115, as shown in FIG. Preferably. Further, the EL layer 103 may include functional layers other than the above-mentioned functional layers, such as a hole blocking layer, an electron blocking layer, an exciton blocking layer, and a charge generation layer. Moreover, conversely, any of the above-mentioned layers may not be provided.

Note that, as described in Embodiment 1, the light-emitting layer 113 included in the EL layer 103 of the present light-emitting device includes a phosphorescent substance, a first organic compound, and a second organic compound. The phosphorescent material, the first organic compound, and the second organic compound have been described in detail in Embodiment Mode 1, and therefore, repeated descriptions will be omitted. Please refer to Embodiment 1.

Note that in this embodiment, the first electrode 101 is described as an electrode containing an anode, and the second electrode 102 is described as an electrode containing a cathode, but this may be reversed. Further, the first electrode 101 and the second electrode 102 are formed as a single layer structure or a stacked structure, and when they have a stacked structure, the layer in contact with the EL layer 103 functions as an anode or a cathode. When the electrode has a laminated structure, there are no restrictions regarding the work function of layers other than the layers that touch the EL layer 103, and materials can be changed according to required properties such as resistance value, processing convenience, reflectance, translucency, and stability. All you have to do is select.

The anode is preferably formed using a metal, an alloy, a conductive compound, a mixture thereof, or the like having a large work function (specifically, 4.0 eV or more). Specifically, for example, indium oxide-tin oxide (ITO), indium tin oxide (ITSO) containing silicon or silicon oxide, indium oxide-zinc oxide, tungsten oxide, and Examples include indium oxide (IWZO) containing zinc oxide. These conductive metal oxide films are usually formed by a sputtering method, but they may also be formed by applying a sol-gel method or the like. As an example of a manufacturing method, indium oxide-zinc oxide may be formed by a sputtering method using a target containing 1 to 20 wt % of zinc oxide to indium oxide. In addition, 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 relative to indium oxide. You can also. In addition, materials used for the anode include, for example, gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt ( Co), copper (Cu), palladium (Pd), titanium (Ti), aluminum (Al), or a nitride of a metal material (eg, titanium nitride). Further, a layer obtained by laminating these may be used as an anode. For example, a film in which Al, Ti, and ITSO are laminated in this order on Ti is preferable because it has good reflectance, is highly efficient, and can achieve high definition of several thousand ppi. Alternatively, graphene can also be used as a material for the anode. Note that by using a composite material that can constitute the hole injection layer 111 (described later) as the layer in contact with the anode (typically the hole injection layer), the electrode material can be selected regardless of the work function. You will be able to do this.

The hole injection layer 111 is provided in contact with the anode, and has a function of facilitating injection of holes into the EL layer 103. The hole injection layer 111 is made of a phthalocyanine compound or complex compound such as phthalocyanine (abbreviation: H ₂ Pc), copper phthalocyanine (abbreviation: CuPc), 4,4'-bis[N-(4-diphenylaminophenyl)- N-phenylamino]biphenyl (abbreviation: DPAB), 4,4'-bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviation: DNTPD), or a polymer such as poly(3,4-ethylenedioxythiophene)/(polystyrene sulfonic acid) (abbreviation: PEDOT/PSS).

Further, the hole injection layer 111 may be formed of a substance that has electron acceptor properties. As the substance having acceptor properties, organic compounds having an electron-withdrawing group (halogen group, cyano group, etc.) can be used. Dimethane (abbreviation: F4-TCNQ), chloranil, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT-CN), 1 , 3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviation: F6-TCNNQ), 2-(7-dicyanomethylene-1,3,4,5,6,8,9, Examples include 10-octafluoro-7H-pyren-2-ylidene) malononitrile. In particular, a compound such as HAT-CN in which an electron-withdrawing group is bonded to a condensed aromatic ring having a plurality of heteroatoms is thermally stable and is therefore preferred. In addition, [3]radialene derivatives having electron-withdrawing groups (particularly halogen groups such as fluoro groups, cyano groups, etc.) are preferable because they have very high electron-accepting properties, and specifically, α, α′, α′′ -1,2,3-cyclopropane triylidene triylidene [4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α, α′, α′′-1,2,3-cyclopropane triylidene Tris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], α,α′,α′′-1,2,3-cyclopropane triylidene tris[2,3, 4,5,6-pentafluorobenzeneacetonitrile] and the like. In addition to the organic compounds described above, transition metal oxides such as molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, and manganese oxide can be used as the substance having acceptor properties.

Further, the hole injection layer 111 is preferably formed of a composite material containing the above-mentioned material having acceptor properties and an organic compound having hole transport properties.

Various organic compounds can be used as organic compounds with hole transport properties for use in composite materials, such as aromatic amine compounds, heteroaromatic compounds, aromatic hydrocarbons, and polymer compounds (oligomers, dendrimers, polymers, etc.). I can do it. Note that the organic compound having hole transport properties used in the composite material is preferably an organic compound having a hole mobility of 1×10 ⁻⁶ cm ² /Vs or more. The organic compound having hole transport properties used in the composite material is preferably a compound having a condensed aromatic hydrocarbon ring or a π-electron-excessive heteroaromatic ring. Preferred examples of the fused aromatic hydrocarbon ring include an anthracene ring and a naphthalene ring. Further, as the π-electron-rich heteroaromatic ring, a fused aromatic ring containing at least one of a pyrrole skeleton, a furan skeleton, and a thiophene skeleton is preferable, and specifically, a carbazole ring, a dibenzothiophene ring, or an aromatic A ring or a ring fused with a heteroaromatic ring is preferred.

The organic compound having such hole-transporting properties preferably has one of a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton. In particular, even if it is an aromatic amine having a substituent containing a dibenzofuran ring or a dibenzothiophene ring, an aromatic monoamine having a naphthalene ring, or an aromatic monoamine in which the 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group. good. Note that it is preferable that the organic compound having hole transporting properties is a substance having an N,N-bis(4-biphenyl)amino group because a light-emitting device with a good lifetime can be produced.

Specifically, the organic compound having hole transport properties as described above includes N-(4-biphenyl)-6,N-diphenylbenzo[b]naphtho[1,2-d]furan-8-amine. (abbreviation: BnfABP), N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf), 4,4'-bis( 6-phenylbenzo[b]naphtho[1,2-d]furan-8-yl)-4''-phenyltriphenylamine (abbreviation: BnfBB1BP), N,N-bis(4-biphenyl)benzo[b] Naphtho[1,2-d]furan-6-amine (abbreviation: BBABnf(6)), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-8-amine ( Abbreviation: BBABnf (8)), N,N-bis(4-biphenyl)benzo[b]naphtho[2,3-d]furan-4-amine (abbreviation: BBABnf (II) (4)), N,N -bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP), N-[4-(dibenzothiophen-4-yl)phenyl]-N-phenyl-4 -biphenylamine (abbreviation: ThBA1BP), 4-(2-naphthyl)-4',4''-diphenyltriphenylamine (abbreviation: BBAβNB), 4-[4-(2-naphthyl)phenyl]-4', 4''-diphenyltriphenylamine (abbreviation: BBAβNBi), 4,4'-diphenyl-4''-(6;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβNB), 4,4' -Diphenyl-4''-(7;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβNB-03), 4,4'-diphenyl-4''-(7-phenyl)naphthyl-2- yltriphenylamine (abbreviation: BBAPβNB-03), 4,4'-diphenyl-4''-(6;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B), 4, 4'-diphenyl-4''-(7; 2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B-03), 4,4'-diphenyl-4''-(4; 2'-binaphthyl-1-yl)triphenylamine (abbreviation: BBAβNαNB), 4,4'-diphenyl-4''-(5;2'-binaphthyl-1-yl)triphenylamine (abbreviation: BBAβNαNB-02) ), 4-(4-biphenylyl)-4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: TPBiAβNB), 4-(3-biphenylyl)-4'-[4-(2- naphthyl)phenyl]-4''-phenyltriphenylamine (abbreviation: mTPBiAβNBi), 4-(4-biphenylyl)-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine ( Abbreviation: TPBiAβNBi), 4-phenyl-4'-(1-naphthyl)triphenylamine (abbreviation: αNBA1BP), 4,4'-bis(1-naphthyl)triphenylamine (abbreviation: αNBB1BP), 4,4' -diphenyl-4′′-[4′-(carbazol-9-yl)biphenyl-4-yl]triphenylamine (abbreviation: YGTBi1BP), 4′-[4-(3-phenyl-9H-carbazol-9-) yl)phenyl]tris(biphenyl-4-yl)amine (abbreviation: YGTBi1BP-02), 4-[4'-(carbazol-9-yl)biphenyl-4-yl]-4'-(2-naphthyl)- 4′′-phenyltriphenylamine (abbreviation: YGTBiβNB), N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-[4-(1-naphthyl)phenyl]-9, 9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBNBSF), N,N-bis(biphenyl-4-yl)-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: BBASF), N,N-bis(biphenyl-4-yl)-9,9'-spirobi[9H-fluorene]-4-amine (abbreviation: BBASF(4)), N-(biphenyl-2-yl)- N-(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi[9H-fluoren]-4-amine (abbreviation: oFBiSF), N-(biphenyl-4-yl)-N -(9,9-dimethyl-9H-fluoren-2-yl)dibenzofuran-4-amine (abbreviation: FrBiF), N-[4-(1-naphthyl)phenyl]-N-[3-(6-phenyldibenzofuran) -4-yl)phenyl]-1-naphthylamine (abbreviation: mPDBfBNBN), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'- (9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-phenyl-4'-[4-(9-phenylfluoren-9-yl)phenyl]triphenylamine (abbreviation: BPAFLBi), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3) -yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'- Di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), N-phenyl-N-[4-(9-phenyl-9H-carbazole) -3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF), N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H) -carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)- 9,9'-spirobi-9H-fluoren-4-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-3-amine , N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-2-amine, N,N-bis(9,9-dimethyl-9H -fluoren-2-yl)-9,9'-spirobi-9H-fluoren-1-amine and the like.

In addition, as materials having hole transport properties, other aromatic amine compounds include N,N'-di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4, 4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), 4,4'-bis(N-{4-[N'-(3-methylphenyl)- N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviation: DNTPD), 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B) etc. can also be used.

By forming the hole injection layer 111, hole injection properties are improved, and a light emitting device with low driving voltage can be obtained.

Note that among substances that have acceptor properties, organic compounds that have acceptor properties are easy to vapor deposit and form a film, so they are materials that are easy to use.

Note that the material used for the hole injection layer 111 may be the first compound.

The hole transport layer 112 is formed containing an organic compound having hole transport properties. The organic compound having hole transport properties preferably has a hole mobility of 1×10 ⁻⁶ cm ² /Vs or more.

The above-mentioned materials having hole transport properties include 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB), N,N'-diphenyl-N,N'- Bis(3-methylphenyl)-4,4'-diaminobiphenyl (abbreviation: TPD), N,N'-bis(9,9'-spirobi[9H-fluoren]-2-yl)-N,N'- Diphenyl-4,4'-diaminobiphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9 -Phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4' -diphenyl-4′′-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4′-(9-phenyl-9H-carbazol-3 -yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N-[4- Compounds with an aromatic amine skeleton such as (9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF), 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), 9,9'-diphenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCP), 9,9'-bis(biphenyl-4-yl)-3,3'- Bi-9H-carbazole (abbreviation: BisBPCz), 9,9'-bis(biphenyl-3-yl)-3,3'-bi-9H-carbazole (abbreviation: BismBPCz), 9-(biphenyl-3-yl) -9'-(biphenyl-4-yl)-9H,9'H-3,3'-bicarbazole (abbreviation: mBPCCBP), 9-(2-naphthyl)-9'-phenyl-9H,9'H- 3,3'-bicarbazole (abbreviation: βNCCP), 9-(3-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviation: βNCCmBP), 9-(4 -biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviation: βNCCBP), 9,9'-di-2-naphthyl-3,3'-9H,9'H -Bicarbazole (abbreviation: BisβNCz), 9-(2-naphthyl)-9'-[1,1':4',1''-terphenyl]-3-yl-3,3'-9H,9'H -Bicarbazole, 9-(2-naphthyl)-9'-[1,1':3',1''-terphenyl]-3-yl-3,3'-9H,9'H-bicarbazole, 9 -(2-naphthyl)-9'-[1,1':3',1''-terphenyl]-5'-yl-3,3'-9H,9'H-bicarbazole, 9-(2- naphthyl)-9'-[1,1':4',1''-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9' -[1,1':3',1''-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-(triphenylene-2 -yl)-3,3'-9H,9'H-bicarbazole, 9-phenyl-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole (abbreviation: PCCzTp ), 9,9'-bis(triphenylen-2-yl)-3,3'-9H, 9'H-bicarbazole, 9-(4-biphenyl)-9'-(triphenylen-2-yl)-3 ,3'-9H,9'H-bicarbazole, 9-(triphenylen-2-yl)-9'-[1,1':3',1"-terphenyl]-4-yl-3,3' Compounds with a carbazole skeleton such as -9H,9'H-bicarbazole, 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) , 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), 4-[4-(9-phenyl-9H-fluorene) Compounds with a thiophene skeleton such as -9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), 4,4',4''-(benzene-1,3,5-triyl)tri( Compounds with a furan skeleton such as dibenzofuran (abbreviation: DBF3P-II), 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II) can be mentioned. Among the above-mentioned compounds, compounds having an aromatic amine skeleton and compounds having a carbazole skeleton are preferable because they have good reliability, high hole transportability, and contribute to reduction in driving voltage. Note that the substances listed as materials having hole transport properties used in the composite material of the hole injection layer 111 can also be suitably used as materials constituting the hole transport layer 112.

As described above, the light-emitting layer 113 in the light-emitting device of one embodiment of the present invention includes a phosphorescent material, a first organic compound, and a second organic compound. Note that when a display device is obtained using the light-emitting device of one embodiment of the present invention, the display device also includes a light-emitting device having a light-emitting layer with a different structure. Further, when the light-emitting device of one embodiment of the present invention has a structure such as a tandem-type light-emitting device in which two or more light-emitting layers are included in the EL layer 103, one of the two light-emitting layers is In some cases, the configuration of Form 1 is not provided. In these cases, the light-emitting layer is a layer containing a light-emitting substance, and preferably contains a light-emitting substance and a host material. Note that the light emitting layer 113 may contain other materials at the same time. Alternatively, it may be a laminate of two layers having different compositions.

The luminescent substance may be a fluorescent substance, a phosphorescent substance, a substance exhibiting thermally activated delayed fluorescence (TADF), or any other luminescent substance.

Examples of materials that can be used as fluorescent substances in the light emitting layer 113 include the following. Further, fluorescent substances other than these can also be used.

5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine (abbreviation: PAP2BPy), 5,6-bis[4'-(10-phenyl-9-anthryl) biphenyl-4-yl]-2,2'-bipyridine (abbreviation: PAPP2BPy), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl] Pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl) phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn), N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenylstilbene-4,4' -diamine (abbreviation: YGA2S), 4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), 4-(9H-carbazol-9-yl) N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H -Carbazol-3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetra-tert-butylperylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)-4'-( 9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), N,N''-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene)bis(N , N',N'-triphenyl-1,4-phenylenediamine) (abbreviation: DPABPA), N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H- Carbazol-3-amine (abbreviation: 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), N, N, N′, N′, N′′, N′′, N′′′, N′′′-octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), coumarin 30, N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCAPA), N-[9,10-bis (Biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCABPhA), N-(9,10-diphenyl-2-anthryl)-N,N' , N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-bis(biphenyl-2-yl)-2-anthryl]-N,N',N'-triphenyl -1,4-phenylenediamine (abbreviation: 2DPABPhA), 9,10-bis(biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracene-2- Amine (abbreviation: 2YGABPhA), N,N,9-triphenylanthracene-9-amine (abbreviation: DPhAPhA), Coumarin 545T, N,N'-diphenylquinacridone (abbreviation: DPQd), rubrene, 5,12-bis( biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyran-4-ylidene ) Propanedinitrile (abbreviation: DCM1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolidin-9-yl)ethenyl]- 4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM2), N,N,N',N'-tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation: p-mPhTD), 7 , 14-diphenyl-N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviation: p-mPhAFD), 2-{2- Isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolidin-9-yl)ethenyl]-4H-pyran- 4-ylidene}propanedinitrile (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H) , 5H-benzo[ij]quinolidin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB), 2-(2,6-bis{2-[4-(dimethylamino) ) phenyl]ethenyl}-4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDCM), 2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-) 2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolidin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJTM), N,N'-diphenyl -N,N'-(1,6-pyrene-diyl)bis[(6-phenylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-03), 3,10-bis[N-(9-phenyl-9H-carbazol-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10PCA2Nbf (IV)-02), 3,10-bis[N-(dibenzofuran-3-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3, 10FrA2Nbf(IV)-02) and the like. In particular, fused aromatic diamine compounds typified by pyrene diamine compounds such as 1,6FLPAPrn, 1,6mMemFLPAPrn, and 1,6BnfAPrn-03 are preferred because they have high hole-trapping properties and excellent luminous efficiency or reliability.

Also, 5,9-diphenyl-5,9-diaza-13b-boranaphtho[3,2,1-de]anthracene (abbreviation: DABNA1), 9-([1,1'-diphenyl]-3-yl)- N,N,5,11-tetraphenyl-5,9-dihydro-5,9-diaza-13b-boranaphtho[3,2,1-de]anthracen-3-amine (abbreviation: DABNA2), 2,12- Di(tert-butyl)-5,9-di(4-tert-butylphenyl)-N,N-diphenyl-5H,9H-[1,4]benzazaborino[2,3,4-kl]phenazaborin-7- Amine (abbreviation: DPhA-tBu4DABNA), 2,12-di(tert-butyl)-N,N,5,9-tetra(4-tert-butylphenyl)-5H,9H-[1,4]benzazaborino[2 ,3,4-kl] phenazaborin-7-amine (abbreviation: tBuDPhA-tBu4DABNA), 2,12-di(tert-butyl)-5,9-di(4-tert-butylphenyl)-7-methyl-5H , 9H-[1,4]benzazaborino[2,3,4-kl]phenazaborin (abbreviation: Me-tBu4DABNA), N ⁷ ,N ⁷ ,N ¹³ ,N ¹³ ,5,9,11,15-octaphenyl- 5H,9H,11H,15H-[1,4]benzazaborino[2,3,4-kl][1,4]benzazaborino[4',3',2':4,5][1,4]benzazaborino[ 3,2-b]phenazaborin-7,13-diamine (abbreviation: ν-DABNA), 2-(4-tert-butylphenyl)benz[5,6]indolo[3,2,1-jk]benzo[b ] Condensed heteroaromatic compounds containing nitrogen and boron such as carbazole (abbreviation: tBuPBibc), especially compounds having a diaza-boranaphtho-anthracene skeleton, are suitable because they have a narrow emission spectrum and can provide blue light emission with good color purity. It can be used for.

In addition to these, 9,10,11-tris[3,6-bis(1,1-dimethylethyl)-9H-carbazolyl-9-yl]-2,5,15,18-tetrakis(1,1 -dimethylethyl)indolo[3,2,1-de]indolo[3',2',1':8,1][1,4]benzazaborino[2,3,4-kl]phenazaborin (abbreviation: BBCz- G), 9,11-bis[3,6-bis(1,1-dimethylethyl)-9H-carbazolyl-9-yl]-2,5,15,18-tetrakis(1,1-dimethylethyl)indolo [3,2,1-de]indolo[3',2',1':8,1][1,4]benzazaborino[2,3,4-kl]phenazaborine (abbreviation: BBCz-Y) and the like are preferred. It can be used for.

In the case of using a phosphorescent material as a light emitting material in the light emitting layer 113, examples of materials that can be used include the following.

Tris {2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN2]phenyl-κC}iridium(III) ( Abbreviation: [Ir(mpptz-dmp) ₃ ]), Tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Mptz) ₃ ]) Tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(Mptz1-mp) ₃ ]), tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Prptz1-Me) ₃ ]), an organometallic iridium complex having a 1H-triazole skeleton, fac-tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviation: [Ir(iPrpim) ) ₃ ]), tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: [Ir(dmpimpt-Me) ₃ ]) ), tris(2-[1-{2,6-bis(1-methylethyl)phenyl}-1H-imidazol-2-yl-κN3]-4-cyanophenyl-κC) (abbreviation: CNImIr) Organometallic iridium complex with imidazole skeleton, tris[(6-tert-butyl-3-phenyl-2H-imidazo[4,5-b]pyrazin-1-yl-κC2)phenyl-κC]iridium(III) (abbreviation) : [Ir(cb) ₃ ]), an organometallic complex having a benzimidazolidene skeleton such as 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) acetylacetonate (abbreviation: FIracac), which uses a phenylpyridine derivative having an electron-withdrawing group as a ligand. It will be done. These are compounds that emit blue phosphorescence, and have an emission peak in the wavelength range from 450 nm to 520 nm.

As for the phosphorescent material, the material shown in Embodiment 1 can be used. Note that an organometallic iridium complex having a pyrimidine skeleton is particularly preferable because it has outstanding reliability and luminous efficiency.

Also, (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III) (abbreviation: [Ir(5mdppm) ₂ (dibm)]), bis[4,6-bis( 3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(5mdppm) ₂ (dpm)]), bis[4,6-di(naphthalen-1-yl)pyrimidinato]( Organometallic iridium complexes with a pyrimidine skeleton, such as dipivaloylmethanato)iridium(III) (abbreviation: [Ir(d1npm) ₂ (dpm)]), (acetylacetonato)bis(2,3,5-tri phenylpyrazinato)iridium(III) (abbreviation: [Ir(tppr) ₂ (acac)]), bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III)( Abbreviation: [Ir(tppr) ₂ (dpm)]), (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: [Ir(Fdpq) ₂ (acac) )), tris(1-phenylisoquinolinato-N,C ^2' )iridium(III) (abbreviation: [Ir(piq) ₃ ]), bis(1-phenyl Isoquinolinato-N,C ^2' )iridium(III) acetylacetonate (abbreviation: [Ir(piq) ₂ (acac)]), (3,7-diethyl-4,6-nonanedionato-κO4,κO6)bis [2,4-dimethyl-6-[7-(1-methylethyl)-1-isoquinolinyl-κN]phenyl-κC]iridium(III), (3,7-diethyl-4,6-nonanedionato-κO4,κO6 ) bis[2,4-dimethyl-6-[5-(1-methylethyl)-2-quinolinyl-κN]phenyl-κC]iridium(III), as well as organometallic iridium complexes having a pyridine skeleton, such as 2 , 3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin Platinum complexes such as platinum(II) (abbreviation: PtOEP), tris(1,3-diphenyl-1,3-propane) dionato) (monophenanthroline) europium(III) (abbreviation: [Eu(DBM) ₃ (Phen)]), tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato] (monophenanthroline) ) rare earth metal complexes such as europium (III) (abbreviation: [Eu(TTA) ₃ (Phen)]). These are compounds that emit red phosphorescence, and have an emission peak in the wavelength range from 600 nm to 700 nm. Furthermore, an organometallic iridium complex having a pyrazine skeleton can emit red light with good chromaticity.

In addition to the phosphorescent compounds described above, known phosphorescent compounds may be selected and used.

As the TADF material, fullerene and its derivatives, acridine and its derivatives, eosin derivatives, etc. can be used. Other metal-containing porphyrins include magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), palladium (Pd), and the like. Examples of the metal-containing porphyrin include protoporphyrin-tin fluoride complex (SnF ₂ (Proto IX)), mesoporphyrin-tin fluoride complex (SnF ₂ (Meso IX)), and hematoporphyrin shown in the following structural formula. - Tin fluoride complex (SnF ₂ (Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF ₂ (Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF ₂ (OEP)) , ethioporphyrin-tin fluoride complex (SnF ₂ (Etio I)), octaethylporphyrin-platinum chloride complex (PtCl ₂ OEP), and the like.

In addition, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5- Triazine (abbreviation: PIC-TRZ), 9-(4,6-diphenyl-1,3,5-triazin-2-yl)-9'-phenyl-9H,9'H-3,3'-bicarbazole ( Abbreviation: PCCzTzn), 9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: PCCzPTzn), 2-[4-(10H-phenoxazin-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: PXZ-TRZ), 3-[4-(5- Phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridine- 10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), 10-phenyl -10H,10'H-spiro[acridine-9,9'-anthracene]-10'-one (abbreviation: ACRSA), one or both of a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring Heterocyclic compounds having the following can also be used. Since the heterocyclic compound has a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring, it has high electron-transporting properties and hole-transporting properties, and is therefore preferable. Among the skeletons having a π-electron-deficient heteroaromatic ring, pyridine skeletons, diazine skeletons (pyrimidine skeletons, pyrazine skeletons, pyridazine skeletons), and triazine skeletons are preferred because they are stable and have good reliability. In particular, a benzofuropyrimidine skeleton, a benzothienopyrimidine skeleton, a benzofuropyrazine skeleton, and a benzothienopyrazine skeleton are preferred because they have high acceptability and good reliability. Furthermore, among the skeletons having a π-electron-rich heteroaromatic ring, at least one of the acridine skeleton, phenoxazine skeleton, phenothiazine skeleton, furan skeleton, thiophene skeleton, and pyrrole skeleton is stable and reliable. It is preferable to have. Note that the furan skeleton is preferably a dibenzofuran skeleton, and the thiophene skeleton is preferably a dibenzothiophene skeleton. Further, as the pyrrole skeleton, particularly preferred are an indole skeleton, a carbazole skeleton, an indolocarbazole skeleton, a bicarbazole skeleton, and a 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole skeleton. In addition, a substance in which a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded has both the electron-donating property of the π-electron-rich heteroaromatic ring and the electron-accepting property of the π-electron-deficient heteroaromatic ring. This is particularly preferable because thermally activated delayed fluorescence can be efficiently obtained because the energy difference between the S ₁ level and the T ₁ level becomes small. Note that instead of the π electron-deficient heteroaromatic ring, an aromatic ring to which an electron-withdrawing group such as a cyano group is bonded may be used. Further, as the π-electron-excessive skeleton, an aromatic amine skeleton, a phenazine skeleton, etc. can be used. In addition, as a π electron-deficient skeleton, a xanthene skeleton, a thioxanthene dioxide skeleton, an oxadiazole skeleton, a triazole skeleton, an imidazole skeleton, an anthraquinone skeleton, a boron-containing skeleton such as phenylborane and boranethrene, and a nitrile such as benzonitrile or cyanobenzene. or a cyano group, an aromatic ring, a heteroaromatic ring, a carbonyl skeleton such as benzophenone, a phosphine oxide skeleton, a sulfone skeleton, etc. can be used. In this way, a π-electron-deficient skeleton and a π-electron-excessive skeleton can be used in place of at least one of the π-electron-deficient heteroaromatic ring and the π-electron-rich heteroaromatic ring.

Note that the TADF material is a material that has a small difference between the S ₁ level and the T ₁ level and has the function of converting energy from triplet excitation energy to singlet excitation energy by reverse intersystem crossing. . Therefore, triplet excitation energy can be up-converted to singlet excitation energy (reverse intersystem crossing) with a small amount of thermal energy, and a singlet excited state can be efficiently generated. Additionally, triplet excitation energy can be converted into luminescence.

In addition, in exciplexes (also called exciplexes, exciplexes, or exciplexes) in which two types of substances form an excited state, the difference between the S ₁ level and the T ₁ level is extremely small, and the triplet excitation energy is compared to the singlet excitation energy. It functions as a TADF material that can be converted into excitation energy.

Note that a phosphorescence spectrum observed at a low temperature (for example, from 77 K to 10 K) may be used as an index of the T ₁ level. For TADF materials, draw a tangent at the short wavelength side of the fluorescence spectrum, set the energy of the wavelength of the extrapolated line as the _S1 level, draw a tangent at the short wavelength side of the phosphorescence spectrum, and use the extrapolation. When the energy of the wavelength of the line is taken as the T ₁ level, the difference between S ₁ and T ₁ is preferably 0.3 eV or less, and more preferably 0.2 eV or less.

Further, when using a TADF material as a light emitting substance, it is preferable that the S ₁ level of the host material is higher than the S ₁ level of the TADF material. Further, it is preferable that the T ₁ level of the host material is higher than the T ₁ level of the TADF material.

As the host material of the light-emitting layer, various carrier transport materials such as a material having an electron transporting property and/or a material having a hole transporting property, and the above-mentioned TADF material can be used.

As the material having hole-transporting properties, organic compounds having an amine skeleton, a π-electron-excessive heteroaromatic ring skeleton, and the like are preferable. The π-electron-rich heteroaromatic ring is preferably a fused aromatic ring containing at least one of an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, a thiophene skeleton, and a pyrrole skeleton, and specifically a carbazole ring. , a dibenzothiophene ring, or a ring in which an aromatic ring or a heteroaromatic ring is further fused thereto.

The organic compound having such hole-transporting properties preferably has one of a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton. In particular, even if it is an aromatic amine having a substituent containing a dibenzofuran ring or a dibenzothiophene ring, an aromatic monoamine having a naphthalene ring, or an aromatic monoamine in which the 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group. good. Note that it is preferable that the organic compound having hole transporting properties is a substance having an N,N-bis(4-biphenyl)amino group because a light-emitting device with a good lifetime can be produced.

Examples of such organic compounds include 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB), N,N'-diphenyl-N,N'-bis (3-methylphenyl)-4,4'-diaminobiphenyl (abbreviation: TPD), N,N'-bis(9,9'-spirobi[9H-fluoren]-2-yl)-N,N'-diphenyl -4,4'-diaminobiphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9- Phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'- Diphenyl-4′′-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4′-(9-phenyl-9H-carbazol-3- yl) triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 9 ,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-( Compounds with an aromatic amine skeleton such as 9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF), 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), compounds having a carbazole skeleton such as 9,9'-diphenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCP), 4,4',4''-(benzene-1 ,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation) :DBTFLP-III), 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and other compounds having a thiophene skeleton, 4,4 ',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II), 4-{3-[3-(9-phenyl-9H-fluoren-9-yl) Examples include compounds having a furan skeleton such as phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II). Among the above-mentioned compounds, compounds having an aromatic amine skeleton or compounds having a carbazole skeleton are preferable because they have good reliability, high hole transportability, and contribute to reduction in driving voltage. Furthermore, the organic compounds listed as examples of materials having hole transport properties in the hole transport layer can also be used.

Examples of materials having electron transport properties include electrons having an electron mobility of 1×10 ⁻⁷ cm 2 /Vs or more, preferably 1×10 ⁻⁶ cm ² /Vs or ^more when the square root of the electric field strength [V/cm] is 600. A substance with mobility is preferred. Note that materials other than these can be used as long as they have a higher transportability for electrons than for holes.

Examples of materials having electron transport properties include bis(10-hydroxybenzo[h]quinolinato) beryllium (II) (abbreviation: BeBq ₂ ), bis(2-methyl-8-quinolinoto)(4-phenylphenolato) aluminum (III) (abbreviation: BAlq), bis(8-quinolinolato)zinc(II) (abbreviation: Znq), bis[2-(2-benzooxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO), bis Metal complexes such as [2-(2-benzothiazolyl)phenolato]zinc (II) (abbreviation: ZnBTZ) and organic compounds having a π electron-deficient heteroaromatic ring are preferred. Examples of organic compounds having a π-electron-deficient heteroaromatic ring skeleton include organic compounds containing a heteroaromatic ring having a polyazole skeleton, organic compounds containing a heteroaromatic ring having a pyridine skeleton, and organic compounds containing a heteroaromatic ring having a diazine skeleton. Compounds and organic compounds containing a heteroaromatic ring having a triazine skeleton can be mentioned.

Among these, organic compounds containing a heteroaromatic ring having a diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), organic compounds containing a heteroaromatic ring having a pyridine skeleton, and organic compounds containing a heteroaromatic ring having a triazine skeleton are highly reliable. It has good properties and is preferable. In particular, organic compounds containing a heteroaromatic ring having a diazine (pyrimidine or pyrazine) skeleton and organic compounds containing a heteroaromatic ring having a triazine skeleton have high electron transport properties and contribute to reduction of driving voltage. Further, a benzofuropyrimidine skeleton, a benzothienopyrimidine skeleton, a benzofuropyrazine skeleton, and a benzothienopyrazine skeleton are preferable because they have high acceptor properties and good reliability.

Examples of organic compounds having a π-electron-deficient heteroaromatic ring skeleton include 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-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl) ) phenyl]-9H-carbazole (abbreviation: CO11), 2,2',2''-(1,3,5-benzentriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOs), 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy), 1,3,5-tri[3- (3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), bathophenanthroline (abbreviation: BPhen), bathocuproine (abbreviation: BCP), 2,9-di(naphthalen-2-yl)-4,7-diphenyl-1, 10-phenanthroline (abbreviation: NBphen), 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P), 2-[3-(2-triphenylenyl)phenyl ]-1,10-phenanthroline (abbreviation: mTpPPhen), 2-phenyl-9-(2-triphenylenyl)-1,10-phenanthroline (abbreviation: Ph-TpPhen), 2-[4-(9-phenanthrenyl)-1 -naphthalenyl]-1,10-phenanthroline (abbreviation: PnNPhen), 2-[4-(2-triphenylenyl)phenyl]-1,10-phenanthroline (abbreviation: pTpPPhen), 2,2'-(biphenyl-4,4 '-diyl)bis(9-phenyl-1,10-phenanthroline) (abbreviation: PPhen2BP), an organic compound containing a heteroaromatic ring with a pyridine skeleton, 2-[3-(dibenzothiophen-4-yl)phenyl] Dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3-(3'-dibenzothiophen-4-yl)biphenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2- [3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4'-(9-phenyl-9H-carbazol-3-yl) )-3,1'-biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mpPCBPDBq), 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[ f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDBTPDBq-II), and 6-[3-( dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 9-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2 ':4,5]furo[2,3-b]pyrazine (abbreviation: 9mDBtBPNfpr), 9-[(3'-dibenzothiophen-4-yl)biphenyl-4-yl]naphtho[1',2':4 ,5] furo[2,3-b]pyrazine (abbreviation: 9pmDBtBPNfpr), 4,6-bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[ 3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), 9 , 9'-[pyrimidine-4,6-diylbis(biphenyl-3,3'-diyl)]bis(9H-carbazole) (abbreviation: 4,6mCzBP2Pm), 8-(biphenyl-4-yl)-4-[ 3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8BP-4mDBtPBfpm), 3,8-bis[3-(dibenzothiophen-4-yl)phenyl ] Benzofuro[2,3-b]pyrazine (abbreviation: 3,8mDBtP2Bfpr), 4,8-bis[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine ( Abbreviation: 4,8mDBtP2Bfpm), 8-[3'-(dibenzothiophen-4-yl)(biphenyl-3-yl)]naphtho[1',2':4,5]furo[3,2-d]pyrimidine (abbreviation: 8mDBtBPNfpm), 8-[(2,2'-binaphthalene)-6-yl]-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d] Pyrimidine (abbreviation: 8(βN2)-4mDBtPBfpm), 2,2'-(pyridine-2,6-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 2,6(P-Bqn)2Py) , 2,2'-(pyridine-2,6-diyl)bis{4-[4-(2-naphthyl)phenyl]-6-phenylpyrimidine} (abbreviation: 2,6(NP-PPm)2Py), 8 -(1,1':4',1''-terphenyl-3-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm), 6-(biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm), 2,6-bis(4-naphthalen-1-ylphenyl)-4-[4-(3-pyridyl)phenyl]pyrimidine (abbreviation: 2,4NP-6PyPPm), 4-[3,5-bis(9H- Carbazol-9-yl)phenyl]-2-phenyl-6-(biphenyl-4-yl)pyrimidine (abbreviation: 6BP-4Cz2PPm), 7-[4-(9-phenyl-9H-carbazol-2-yl)quinazoline -2-yl]-7H-dibenzo[c,g]carbazole (abbreviation: PC-cgDBCzQz), an organic compound having a diazine skeleton, 2-(biphenyl-4-yl)-4-phenyl-6-(9, 9'-spirobi[9H-fluoren]-2-yl)-1,3,5-triazine (abbreviation: BP-SFTzn), 2-{3-[3-(benzo[b]naphtho[1,2-d ]Furan-8-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn), 2-{3-[3-(benzo[b]phth[1,2- d]furan-6-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn-02), 9-[4-(4,6-diphenyl-1,3, 5-triazin-2-yl)phenyl]-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: PCCzPTzn), 9-[3-(4,6-diphenyl-1,3,5- triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), 2-[3'-(9,9-dimethyl-9H-fluorene-2) -yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn), 5-[3-(4,6-diphenyl-1,3,5-triazine-2) -yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviation: mINc(II)PTzn), 2-{3-[3-(dibenzothiophen-4-yl) ) phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mDBtBPTzn), 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]- 1,3,5-triazine (abbreviation: TmPPPyTz), 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3, 5-triazine (abbreviation: mPn-mDMePyPTzn), 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazin-2-yl]-11,12-dihydro-12-phenyl -indolo[2,3-a]carbazole (abbreviation: BP-Icz(II)Tzn), 2-[3'-(triphenylen-2-yl)biphenyl-3-yl]-4,6-diphenyl-1, 3,5-triazine (abbreviation: mTpBPTzn), 3-[9-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]-9-phenyl-9H-carbazole (abbreviation: PCDBfTzn), 2-(biphenyl-3-yl)-4-phenyl-6-{8-[(1,1':4',1''-terphenyl)-4-yl]-1- Examples include organic compounds containing a heteroaromatic ring having a triazine skeleton, such as dibenzofuranyl}-1,3,5-triazine (abbreviation: mBP-TPDBfTzn). Furthermore, organic compounds containing a heteroaromatic ring having a diazine skeleton, organic compounds containing a heteroaromatic ring having a pyridine skeleton, and organic compounds containing a heteroaromatic ring having a triazine skeleton are preferable because of their good reliability. In particular, organic compounds containing a heteroaromatic ring having a diazine (pyrimidine or pyrazine) skeleton and organic compounds containing a heteroaromatic ring having a triazine skeleton have high electron transport properties and contribute to reduction of driving voltage.

As the TADF material that can be used as the host material, those listed above as the TADF material can be similarly used. When a TADF material is used as a host material, the triplet excitation energy generated in the TADF material is converted into singlet excitation energy by reverse intersystem crossing, and the energy is further transferred to the luminescent substance, thereby increasing the luminous efficiency of the light-emitting device. be able to. At this time, the TADF material functions as an energy donor, and the luminescent material functions as an energy acceptor.

This is very effective when the luminescent substance is a fluorescent luminescent substance. Further, at this time, in order to obtain high luminous efficiency, it is preferable that the S ₁ level of the TADF material is higher than the S ₁ level of the fluorescent material. Further, the T ₁ level of the TADF material is preferably higher than the S ₁ level of the fluorescent material. Therefore, the T ₁ level of the TADF material is preferably higher than the T ₁ level of the fluorescent material.

Furthermore, it is preferable to use a TADF material that emits light that overlaps the wavelength of the lowest energy absorption band of the fluorescent substance. This is preferable because excitation energy can be smoothly transferred from the TADF material to the fluorescent substance, and luminescence can be efficiently obtained.

Furthermore, in order to efficiently generate singlet excitation energy from triplet excitation energy by reverse intersystem crossing, it is preferable that carrier recombination occurs in the TADF material. Further, it is preferable that the triplet excitation energy generated in the TADF material does not transfer to the triplet excitation energy of the fluorescent substance. For this purpose, it is preferable that the fluorescent substance has a protective group around the luminophore (skeleton that causes luminescence) of the fluorescent substance. The protecting group is preferably a substituent having no π bond, preferably a saturated hydrocarbon, specifically an alkyl group having 3 or more and 10 or less carbon atoms, a substituted or unsubstituted cyclo group having 3 or more and 10 or less carbon atoms. Examples include an alkyl group and a trialkylsilyl group having 3 to 10 carbon atoms, and it is more preferable to have a plurality of protecting groups. Since substituents that do not have a π bond have poor carrier transport function, the distance between the TADF material and the luminophore of the fluorescent substance can be increased with little effect on carrier transport or carrier recombination. . Here, the term "luminophore" refers to an atomic group (skeleton) that causes luminescence in a fluorescent substance. The luminophore preferably has a skeleton having a π bond, preferably contains an aromatic ring, and preferably has a fused aromatic ring or a fused heteroaromatic ring. Examples of the fused aromatic ring or fused heteroaromatic ring include a phenanthrene skeleton, a stilbene skeleton, an acridone skeleton, a phenoxazine skeleton, a phenothiazine skeleton, and the like. In particular, fluorescent substances having a naphthalene skeleton, anthracene skeleton, fluorene skeleton, chrysene skeleton, triphenylene skeleton, tetracene skeleton, pyrene skeleton, perylene skeleton, coumarin skeleton, quinacridone skeleton, or naphthobisbenzofuran skeleton are preferable because they have a high fluorescence quantum yield.

When a fluorescent substance is used as a luminescent substance, a material having an anthracene skeleton is suitable as the host material. When a substance having an anthracene skeleton is used as a host material for a fluorescent substance, it is possible to realize a light-emitting layer with good luminous efficiency and durability. As the substance having an anthracene skeleton used as the host material, a substance having a diphenylanthracene skeleton, particularly a 9,10-diphenylanthracene skeleton is preferable because it is chemically stable. Furthermore, when the host material has a carbazole skeleton, it is preferable because the hole injection/transport properties are enhanced, but when the host material contains a benzocarbazole skeleton in which a benzene ring is further condensed to the carbazole, the HOMO becomes about 0.1 eV shallower than that of carbazole. , is more preferable because holes can easily enter. In particular, when the host material contains a dibenzocarbazole skeleton, the HOMO becomes about 0.1 eV shallower than that of carbazole, which makes it easier for holes to enter, and it is also preferable because it has excellent hole transportability and high heat resistance. . Therefore, more preferable host materials are substances having both a 9,10-diphenylanthracene skeleton and a carbazole skeleton (or a benzocarbazole skeleton or a dibenzocarbazole skeleton). Note that from the viewpoint of hole injection/transport properties, a benzofluorene skeleton or a dibenzofluorene skeleton may be used instead of the carbazole skeleton. Examples of such substances include 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), 3-[4-(1-naphthyl)phenyl ]-9-phenyl-9H-carbazole (abbreviation: PCPN), 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: CzPA), 7-[4-(10-phenyl) -9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA), 6-[3-(9,10-diphenyl-2-anthryl)phenyl]benzo[b]naphtho[1,2 -d]furan (abbreviation: 2mBnfPPA), 9-phenyl-10-[4-(9-phenyl-9H-fluoren-9-yl)biphenyl-4'-yl]anthracene (abbreviation: FLPPA), 9-(1 -naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: αN-βNPAnth), 9-(1-naphthyl)-10-(2-naphthyl)anthracene (abbreviation: α,βADN), 2 -(10-phenylanthracen-9-yl)dibenzofuran, 2-(10-phenyl-9-anthracenyl)benzo[b]naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA), 9-( 2-naphthyl)-10-[3-(2-naphthyl)phenyl]anthracene (abbreviation: βN-mβNPAnth), 1-{4-[10-(biphenyl-4-yl)-9-anthracenyl]phenyl}-2 -ethyl-1H-benzimidazole (abbreviation: EtBImPBPhA), and the like. In particular, CzPA, cgDBCzPA, 2mBnfPPA, and PCzPA exhibit very good properties and are therefore preferred choices.

Note that the host material may be a material that is a mixture of multiple types of substances, and when using a mixed host material, it is preferable to mix a material that has an electron transport property and a material that has a hole transport property. . By mixing a material having an electron transporting property and a material having a hole transporting property, the transporting property of the light emitting layer 113 can be easily adjusted, and the recombination region can also be easily controlled. The weight ratio of the content of the material having a hole transporting property and the material having an electron transporting property may be such that the material having a hole transporting property: the material having an electron transporting property = 1:19 to 19:1.

Note that a phosphorescent substance can be used as part of the above-mentioned mixed material. The phosphorescent substance can be used as an energy donor that provides excitation energy to the fluorescent substance when the fluorescent substance is used as the luminescent substance.

Moreover, an exciplex may be formed by these mixed materials. By selecting a combination of exciplexes that form an exciplex that emits light that overlaps with the wavelength of the lowest energy absorption band of the luminescent substance, energy transfer becomes smoother and luminescence can be efficiently obtained. preferable. Further, by using this configuration, the driving voltage is also reduced, which is preferable.

Note that at least one of the materials forming the exciplex may be a phosphorescent substance. By doing so, triplet excitation energy can be efficiently converted to singlet excitation energy by reverse intersystem crossing.

As a combination of materials that can efficiently form an exciplex, it is preferable that the HOMO level of the material having hole transporting properties is higher than the HOMO level of the material having electron transporting properties. Further, it is preferable that the LUMO level of the material having hole transporting properties is higher than the LUMO level of the material having electron transporting properties. Note that the LUMO level and HOMO level of the material can be derived from the electrochemical properties (reduction potential and oxidation potential) of the material measured by cyclic voltammetry (CV) measurement.

The formation of an exciplex is determined by comparing, for example, the emission spectrum of a material with hole-transporting properties, the emission spectrum of a material with electron-transporting properties, and the emission spectrum of a mixed film made by mixing these materials. This can be confirmed by observing the phenomenon that the emission spectrum of each material shifts to longer wavelengths (or has a new peak on the longer wavelength side). Alternatively, by comparing the transient photoluminescence (PL) of a material with hole-transporting properties, the transient PL of a material with electron-transporting properties, and the transient PL of a mixed film made by mixing these materials, the transient PL life of the mixed film is calculated as follows: This can be confirmed by observing differences in transient response, such as having a longer-life component than the transient PL life of each material, or having a larger proportion of delayed components. Moreover, the above-mentioned transient PL may be read as transient electroluminescence (EL). In other words, by comparing the transient EL of a material with hole-transporting properties, the transient EL of a material with electron-transporting properties, and the transient EL of a mixed film of these, and observing the differences in transient responses, it is possible to determine the formation of exciplexes. It can be confirmed.

The electron transport layer 114 is formed as a layer containing a substance having electron transport properties. Examples of materials having electron transport properties include electrons having an electron mobility of 1×10 ⁻⁷ cm 2 /Vs or more, preferably 1×10 ⁻⁶ cm ² /Vs or ^more when the square root of the electric field strength [V/cm] is 600. A substance with mobility is preferred. Note that materials other than these can be used as long as they have a higher transportability for electrons than for holes. In addition, as the above-mentioned organic compound, an organic compound having a π electron deficient heteroaromatic ring is preferable. Examples of organic compounds having a π-electron-deficient heteroaromatic ring include organic compounds containing a heteroaromatic ring having a polyazole skeleton, organic compounds containing a heteroaromatic ring having a pyridine skeleton, and organic compounds containing a heteroaromatic ring having a diazine skeleton. and an organic compound containing a heteroaromatic ring having a triazine skeleton.

As the organic compound having an electron transporting property that can be used in the electron transporting layer 114, an organic compound that can be used as the organic compound having an electron transporting property in the light emitting layer 113 can be similarly used. Among these, organic compounds containing a heteroaromatic ring having a diazine skeleton, organic compounds containing a heteroaromatic ring having a pyridine skeleton, and organic compounds containing a heteroaromatic ring having a triazine skeleton are preferable because of their good reliability. In particular, organic compounds containing a heteroaromatic ring having a diazine (pyrimidine or pyrazine) skeleton and organic compounds containing a heteroaromatic ring having a triazine skeleton have high electron transport properties and contribute to reduction of driving voltage. Among them, organic compounds having a phenanthroline skeleton such as mTpPPhen, PnNPhen and mPPhen2P are preferred, and organic compounds having a phenanthroline dimer structure such as mPPhen2P are more preferred because of their excellent stability.

Note that the electron transport layer 114 may have a laminated structure. Further, a layer in contact with the light emitting layer 113 in the electron transport layer 114 having a stacked structure may function as a hole blocking layer. When the electron transport layer in contact with the light emitting layer functions as a hole blocking layer, it is preferable to use a material whose HOMO level is deeper than the HOMO level of the material included in the light emitting layer 113 by 0.5 eV or more.

As the electron injection layer 115, an alkali metal or alkaline earth metal such as lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF ₂ ), 8-hydroxyquinolinate-lithium (abbreviation: Liq), etc. A layer containing a metal or a compound thereof, or 1,1'-pyridine-2,6-diyl-bis(1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine ) (abbreviation: hpp2Py) may be provided. The electron injection layer 115 may be a layer made of a substance having electron transport properties containing an alkali metal, an alkaline earth metal, or a compound thereof, or an electride. Examples of the electride include a substance obtained by adding a high concentration of electrons to a mixed oxide of calcium and aluminum.

As the electron injection layer 115, a substance having an electron transporting property (preferably an organic compound having a bipyridine skeleton) contains the above-mentioned alkali metal or alkaline earth metal fluoride at a concentration of at least a microcrystalline state (50 wt% or more). It is also possible to use layered layers. Since the layer has a low refractive index, it is possible to provide a light emitting device with better external quantum efficiency.

For the electron injection layer 115, in addition to using the above-mentioned substances alone, a layer made of a substance having an electron transporting property and containing them may be used.

Further, a charge generation layer 116 may be provided instead of the electron injection layer 115 (FIG. 1(B)). The charge generation layer 116 is a layer that can inject holes into the layer in contact with the cathode side and electrons into the layer in contact with the anode side by applying a potential. The charge generation layer 116 includes at least a P-type layer 117. It is preferable that the P-type layer 117 be formed using the composite material listed as a material that can constitute the hole injection layer 111 described above. Further, the P-type layer 117 may be formed by laminating a film containing the acceptor material and a film containing the hole transport material described above as the materials constituting the composite material. By applying a potential to the P-type layer 117, electrons are injected into the electron transport layer 114 and holes are injected into the cathode, thereby operating the light emitting device.

Note that, in addition to the P-type layer 117, the charge generation layer 116 preferably includes one or both of an electronic relay layer 118 and an N-type layer 119.

The electron relay layer 118 contains at least a substance having an electron transport property, and has a function of preventing interaction between the N-type layer 119 and the P-type layer 117 and smoothly transferring electrons. The LUMO level of the substance with electron transport properties included in the electron relay layer 118 is the LUMO level of the acceptor substance in the P-type layer 117 and the LUMO level of the substance included in the layer in contact with the charge generation layer 116 in the electron transport layer 114. It is preferably between the LUMO level. The specific energy level of the LUMO level in the material having electron transport properties used in the electron relay layer 118 is preferably −5.0 eV or more, preferably −5.0 eV or more and −3.0 eV or less. Note that as the substance having electron transport properties used in the electron relay layer 118, it is preferable to use a phthalocyanine-based material or a metal complex having a metal-oxygen bond and an aromatic ligand.

The N-type layer 119 contains alkali metals, alkaline earth metals, rare earth metals, and compounds thereof (alkali metal compounds (including oxides such as lithium oxide, halides, carbonates such as lithium carbonate and cesium carbonate), It is possible to use substances with high electron injection properties such as alkaline earth metal compounds (including oxides, halides, and carbonates) or rare earth metal compounds (including oxides, halides, and carbonates). be.

In addition, when the N-type layer 119 is formed containing a substance having electron transport properties and a donor substance, the donor substance may include alkali metals, alkaline earth metals, rare earth metals, and compounds thereof (alkali Metal compounds (including oxides such as lithium oxide, halides, carbonates such as lithium carbonate and cesium carbonate), alkaline earth metal compounds (including oxides, halides and carbonates), or rare earth metal compounds ( In addition to organic compounds (including oxides, halides, and carbonates), organic compounds such as tetrathianaphthacene (abbreviation: TTN), nickelocene, and decamethylnickelocene can also be used. Note that the substance having electron transport properties can be formed using the same material as the material constituting the electron transport layer 114 described above.

The second electrode 102 is an electrode including a cathode. The second electrode 102 may have a laminated structure, in which case the layer in contact with the EL layer 103 functions as a cathode. As the material forming the cathode, metals, alloys, electrically conductive compounds, and mixtures thereof having a small work function (specifically, 3.8 eV or less) can be used. Specific examples of such cathode materials include alkali metals such as lithium (Li) or cesium (Cs), and metals from Group 1 of the periodic table of elements such as magnesium (Mg), calcium (Ca), and strontium (Sr). Elements belonging to Group 2, alloys containing these (MgAg, AlLi), compounds (lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF ₂ ), etc.), europium (Eu), ytterbium Examples include rare earth metals such as (Yb) and alloys containing these metals. However, by providing the electron injection layer 115 or a thin film of the above-mentioned material with a small work function between the second electrode 102 and the electron transport layer, Al, Ag, ITO, silicon, or Various conductive materials can be used as the cathode, such as indium oxide-tin oxide containing silicon oxide.

Note that when the second electrode 102 is formed of a material that is transparent to visible light, a light-emitting device that emits light from the second electrode 102 side can be obtained.

These conductive materials can be formed into a film using a dry method such as a vacuum evaporation method or a sputtering method, an inkjet method, a spin coating method, or the like. Further, it may 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.

Furthermore, various methods can be used to form the EL layer 103, regardless of whether it is a dry method or a wet method. For example, a vacuum deposition method, a gravure printing method, an offset printing method, a screen printing method, an inkjet method, or a spin coating method may be used.

Further, each electrode or each layer described above may be formed using different film forming methods.

Next, an embodiment of a light emitting device having a structure in which a plurality of light emitting units are stacked (also referred to as a stacked device or a tandem device) will be described with reference to FIG. 1(C). This organic EL element is a light emitting device having a plurality of light emitting units between an anode and a cathode. One light emitting unit has almost the same structure as the EL layer 103 shown in FIG. 1(A). In other words, the organic EL device shown in FIG. 1(C) is an organic EL device having a plurality of light emitting units, and the organic EL device shown in FIGS. 1(A) and 1(B) is an organic EL device having one light emitting unit. It can be said that it is a light emitting device.

In FIG. 1C, a first light emitting unit 511 and a second light emitting unit 512 are stacked between a first electrode 501 and a second electrode 502. A charge generation layer 513 is provided between the second light emitting unit 512 and the second light emitting unit 512 . The first electrode 501 and the second electrode 502 correspond to the first electrode 101 and the second electrode 102 in FIG. 1(A), respectively, and the same ones as described in the explanation of FIG. 1(A) are applied. can do. Further, the first light emitting unit 511 and the second light emitting unit 512 may have the same configuration or different configurations.

The charge generation layer 513 has a function of injecting electrons into one light emitting unit and injecting holes into the other light emitting unit when a voltage is applied to the first electrode 501 and the second electrode 502. That is, in FIG. 1C, when a voltage is applied such that the potential of the anode is higher than the potential of the cathode, the charge generation layer 513 injects electrons into the first light emitting unit 511 and injects electrons into the second light emitting unit 511. Any device that injects holes into the light emitting unit 512 may be used.

The charge generation layer 513 is preferably formed to have the same structure as the charge generation layer 116 described with reference to FIG. 1B. The composite material of an organic compound and a metal oxide used in the P-type layer has excellent carrier injection properties and carrier transport properties, so that low voltage drive and low current drive can be realized. Note that when the anode side surface of the light emitting unit is in contact with the charge generation layer 513, the charge generation layer 513 can also play the role of the hole injection layer of the light emitting unit. It is not necessary to set it up.

Further, it is preferable that the charge generation layer 513 is provided with an N-type layer 119. Note that when the N-type layer 119 is formed in the intermediate layer, the N-type layer 119 plays the role of an electron injection layer in the anode-side light-emitting unit. It is not necessarily necessary to form an electron injection layer.

In FIG. 1C, a light-emitting device having two light-emitting units has been described, but the present invention can be similarly applied to a light-emitting device in which three or more light-emitting units are stacked. As in the light-emitting device according to this embodiment, by arranging a plurality of light-emitting units between a pair of electrodes and partitioned by a charge generation layer 513, high-intensity light emission is possible while keeping the current density low. A long-life device can be realized. Furthermore, a light emitting device that can be driven at low voltage and consumes low power can be realized.

In addition, by making each light emitting unit emit light of a different color, the light emitting device as a whole can emit light of a desired color. For example, in a light-emitting device having two light-emitting units, by emitting red and green light from the first light-emitting unit and blue light from the second light-emitting unit, a light-emitting device that emits white light can be obtained. It is also possible.

Further, each layer and electrode such as the EL layer 103, the first light emitting unit 511, the second light emitting unit 512, and the charge generation layer described above can be formed by, for example, a vapor deposition method (including a vacuum vapor deposition method), a droplet discharge method (ink jet It can be formed using a method such as a coating method, a gravure printing method, etc. They may also include low-molecular materials, medium-molecular materials (including oligomers and dendrimers), or polymeric materials.

(Embodiment 2)
In this embodiment, a display device using the light-emitting device described in Embodiment 1 will be described.

In this embodiment, a display device manufactured using the light-emitting device described in Embodiment 1 will be described with reference to FIG. 2. Note that FIG. 2(A) is a top view showing the display device, and FIG. 2(B) is a cross-sectional view taken along AB and CD in FIG. 2(A). This display device includes a drive circuit section (source line drive circuit) 601, a pixel section 602, and a drive circuit section (gate line drive circuit) 603 shown by dotted lines, which control the light emission of the light emitting device. Further, 604 is a sealing substrate, 605 is a sealing material, and the inside surrounded by the sealing material 605 is a space 607.

Note that the routing wiring 608 is a wiring for transmitting signals input to the source line driving circuit 601 and the gate line driving circuit 603, and receives video signals, clock signals, Receives start signals, reset signals, etc. Note that although only the FPC is illustrated here, a printed wiring board (PWB) may be attached to the FPC. The display device in this specification includes not only a display device main body but also a state in which an FPC or PWB is attached to the display device main body.

Next, the cross-sectional structure will be explained using FIG. 2(B). A drive circuit section and a pixel section are formed on the element substrate 610, and here, a source line drive circuit 601, which is the drive circuit section, and one pixel in the pixel section 602 are shown.

The element substrate 610 is manufactured using a substrate made of glass, quartz, organic resin, metal, alloy, semiconductor, etc., as well as a plastic substrate made of FRP (Fiber Reinforced Plastics), PVF (Polyvinyl Fluoride), polyester, acrylic resin, etc. do it.

The structures of transistors used in pixels and drive circuits are not particularly limited. For example, it may be an inverted staggered transistor or a staggered transistor. Further, a top gate type transistor or a bottom gate type transistor may be used. The semiconductor material used for the transistor is not particularly limited, and for example, silicon, germanium, silicon carbide, gallium nitride, etc. can be used. Alternatively, an oxide semiconductor containing at least one of indium, gallium, and zinc, such as an In-Ga-Zn-based metal oxide, may be used.

The crystallinity of the semiconductor material used for the transistor is not particularly limited, and it may be either an amorphous semiconductor, a semiconductor with crystallinity (a microcrystalline semiconductor, a polycrystalline semiconductor, a single crystal semiconductor, or a semiconductor partially having a crystalline region). may also be used. It is preferable to use a semiconductor having crystallinity because deterioration of transistor characteristics can be suppressed.

Here, in addition to transistors provided in the pixels and drive circuits described above, oxide semiconductors are preferably used in semiconductor devices such as transistors used in touch sensors and the like described later. In particular, it is preferable to use an oxide semiconductor having a wider band gap than silicon. By using an oxide semiconductor with a wider bandgap than silicon, the current in the off-state of the transistor can be reduced.

The oxide semiconductor preferably contains at least indium (In) or zinc (Zn). In addition, it must be an oxide semiconductor containing an oxide expressed as an In-M-Zn-based oxide (M is a metal such as Al, Ti, Ga, Ge, Y, Zr, Sn, La, Ce, or Hf). is more preferable.

In particular, the semiconductor layer has a plurality of crystal parts, the c-axes of the crystal parts are oriented perpendicular to the surface on which the semiconductor layer is formed, or the top surface of the semiconductor layer, and there are grain boundaries between adjacent crystal parts. It is preferable to use an oxide semiconductor film that does not have.

By using such a material for the semiconductor layer, fluctuations in electrical characteristics can be suppressed and a highly reliable transistor can be realized.

Further, due to the low off-state current of the transistor including the above-described semiconductor layer, it is possible to retain charge accumulated in the capacitor via the transistor for a long period of time. By applying such a transistor to a pixel, it is also possible to stop the drive circuit while maintaining the gradation of the image displayed in each display area. As a result, it is possible to realize an electronic device with extremely reduced power consumption.

In order to stabilize the characteristics of the transistor, it is preferable to provide a base film. As the base film, an inorganic insulating film such as a silicon oxide film, a silicon nitride film, a silicon oxynitride film, and a silicon nitride oxide film can be used, and it can be formed as a single layer or in a stacked manner. The base film is formed using sputtering method, CVD (Chemical Vapor Deposition) method (plasma CVD method, thermal CVD method, MOCVD (Metal Organic CVD) method, etc.), ALD (Atomic Layer Deposition) method, coating method, printing method, etc. can. Note that the base film does not need to be provided if it is not necessary.

Note that the FET 623 represents one of the transistors formed in the drive circuit 601. Further, the drive circuit may be formed of various CMOS circuits, PMOS circuits, or NMOS circuits. Furthermore, although this embodiment shows a driver-integrated type in which a drive circuit is formed on a substrate, this is not necessarily necessary, and the drive circuit can be formed outside instead of on the substrate.

Further, the pixel portion 602 is formed of a plurality of pixels including a switching FET 611, a current control FET 612, and a first electrode 613 electrically connected to the drain thereof, but is not limited to this. The pixel portion may be a combination of three or more FETs and a capacitive element.

Note that an insulator 614 is formed to cover the end of the first electrode 613. Here, it can be formed by using a positive photosensitive acrylic resin film.

Further, in order to improve the coverage of the organic compound layer and the like to be formed later, a curved surface having a curvature is formed at the upper end or the lower end of the insulator 614. For example, when a positive photosensitive acrylic resin is used as the material for the insulator 614, it is preferable that only the upper end of the insulator 614 has a curved surface with a radius of curvature (0.2 μm to 3 μm). Further, as the insulator 614, either a negative photosensitive resin or a positive 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 with a large work function. For example, a single layer film such as 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, a chromium film, a tungsten film, a Zn film, a Pt film, etc. In addition, a stacked structure of a titanium nitride film and a film mainly composed of aluminum, a three-layer structure of a titanium nitride film, a film mainly composed of aluminum, and a titanium nitride film, etc. can be used. Note that if the layered structure is used, the resistance as a wiring is low, good ohmic contact can be made, and furthermore, it can function as an anode.

Further, the EL layer 616 is formed by various methods such as a vapor deposition method using a vapor deposition mask, an inkjet method, and a spin coating method. EL layer 616 includes the configuration described in Embodiment 1. Further, other materials constituting the EL layer 616 may be low molecular compounds or high molecular compounds (including oligomers and dendrimers).

Further, as the material used for the second electrode 617 formed on the EL layer 616 and functioning as a cathode, materials with a small work function (Al, Mg, Li, Ca, or alloys and compounds thereof (MgAg, MgIn, It is preferable to use AlLi, etc.). Note that when the light generated in the EL layer 616 is transmitted through the second electrode 617, the second electrode 617 is made of a thin metal film and a transparent conductive film (ITO, 2 to 20 wt% oxide). It is preferable to use a stack of indium oxide containing zinc, indium tin oxide containing silicon, zinc oxide (ZnO), etc.).

Note that a light emitting device is formed by the first electrode 613, the EL layer 616, and the second electrode 617. The light-emitting device is the light-emitting device described in Embodiment 1. Note that although a plurality of light-emitting devices are formed in the pixel portion, the display device in this embodiment includes both the light-emitting device described in Embodiment 1 and a light-emitting device having a different structure. It's okay to do so.

Furthermore, by bonding the sealing substrate 604 to the element substrate 610 using a sealant 605, a structure is created in which a light emitting device 618 is provided in a space 607 surrounded by the element substrate 610, the sealing substrate 604, and the sealant 605. There is. Note that the space 607 is filled with a filler, and in addition to being filled with an inert gas (nitrogen, argon, etc.), it may also be filled with a sealing material. By forming a recess in the sealing substrate and providing a desiccant material therein, deterioration due to the influence of moisture can be suppressed, which is a preferable configuration.

Note that it is preferable to use epoxy resin or glass frit for the sealing material 605. Further, it is desirable that these materials are as impervious to moisture and oxygen as possible. Furthermore, as a material for the sealing substrate 604, in addition to a glass substrate and a quartz substrate, a plastic substrate made of FRP (Fiber Reinforced Plastics), PVF (Polyvinyl Fluoride), polyester, acrylic resin, or the like can be used.

Although not shown in FIG. 2, a protective film may be provided on the second electrode. The protective film may be formed of an organic resin film or an inorganic insulating film. Further, a protective film may be formed to cover the exposed portion of the sealing material 605. Further, the protective film can be provided to cover the exposed side surfaces of the surfaces and side surfaces of the pair of substrates, the sealing layer, the insulating layer, and the like.

The protective film can be made of a material that is difficult for impurities such as water to pass through. Therefore, diffusion of impurities such as water from the outside to the inside can be effectively suppressed.

As the material constituting the protective film, oxides, nitrides, fluorides, sulfides, ternary compounds, metals, or polymers can be used. For example, aluminum oxide, hafnium oxide, hafnium silicate, lanthanum oxide, lanthanum oxide, etc. Materials containing silicon, strontium titanate, tantalum oxide, titanium oxide, zinc oxide, niobium oxide, zirconium oxide, tin oxide, yttrium oxide, cerium oxide, scandium oxide, erbium oxide, vanadium oxide or indium oxide, aluminum nitride, nitride Materials containing hafnium, silicon nitride, tantalum nitride, titanium nitride, niobium nitride, molybdenum nitride, zirconium nitride or gallium nitride, etc., nitrides containing titanium and aluminum, oxides containing titanium and aluminum, oxides containing aluminum and zinc , sulfides containing manganese and zinc, sulfides containing cerium and strontium, oxides containing erbium and aluminum, oxides containing yttrium and zirconium, and the like can be used.

The protective film is preferably formed using a film forming method that provides good step coverage. One such method is an atomic layer deposition (ALD) method. It is preferable to use a material that can be formed using an ALD method for the protective film. By using the ALD method, it is possible to form a protective film that is dense, has fewer defects such as cracks and pinholes, or has a uniform thickness. Furthermore, damage to the processed member when forming the protective film can be reduced.

For example, by forming a protective film using an ALD method, it is possible to form a uniform protective film with few defects even on a surface having a complicated uneven shape, the top surface, side surfaces, and back surface of a touch panel.

In the above manner, a display device manufactured using the light-emitting device described in Embodiment 1 can be obtained.

Since the display device in this embodiment uses the light-emitting device described in Embodiment 1, a display device with good characteristics can be obtained. Specifically, since the light-emitting device described in Embodiment 1 has high luminous efficiency, it is possible to provide a display device with low power consumption. Further, since the light-emitting device described in Embodiment 1 has good reliability, a display device with good reliability can be obtained.

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

(Embodiment 3)
As illustrated in FIGS. 3A and 3B, a plurality of light emitting devices 130 are formed on the insulating layer 175 to constitute a display device. In this embodiment, a display device according to another embodiment of the present invention will be described in detail.

The display device 100 includes a pixel section 177 in which a plurality of pixels 178 are arranged in a matrix. Pixel 178 has subpixel 110R, subpixel 110G, and subpixel 110B.

In this specification and the like, when describing matters common to the sub-pixel 110R, the sub-pixel 110G, and the sub-pixel 110B, the sub-pixel 110 may be referred to as the sub-pixel 110. Regarding other constituent elements that are distinguished by alphabets, when explaining matters common to these components, symbols omitting the alphabets may be used in the explanation.

Subpixel 110R emits red light, subpixel 110G emits green light, and subpixel 110B emits blue light. Thereby, an image can be displayed on the pixel section 177. Note that in this embodiment, subpixels of three colors red (R), green (G), and blue (B) will be used as an example, but combinations of subpixels of other colors may be used. . Further, the number of sub-pixels is not limited to three, and may be four or more. Examples of the four subpixels include subpixels of four colors R, G, B, and white (W), subpixels of four colors R, G, B, and yellow (Y), and subpixels of four colors R, G, B, and yellow (Y). , four subpixels for infrared light (IR), and the like.

In this specification and the like, the row direction is sometimes referred to as the X direction, and the column direction is sometimes referred to as the Y direction. The X direction and the Y direction intersect, for example, perpendicularly.

FIG. 3A shows an example in which subpixels of different colors are arranged side by side in the X direction, and subpixels of the same color are arranged side by side in the Y direction. Note that subpixels of different colors may be arranged side by side in the Y direction, and subpixels of the same color may be arranged side by side in the X direction.

A connecting portion 140 may be provided outside the pixel portion 177, and a region 141 may be provided. The region 141 is provided between the pixel section 177 and the connection section 140. The EL layer 103 is provided in the region 141. Furthermore, the connection portion 140 is provided with a conductive layer 151C.

Although FIG. 3A shows an example in which the region 141 and the connecting portion 140 are located on the right side of the pixel portion 177, the positions of the region 141 and the connecting portion 140 are not particularly limited. Further, the region 141 and the connecting portion 140 may be singular or plural.

FIG. 3(B) is an example of a cross-sectional view taken along the dashed-dotted line A1-A2 in FIG. 3(A). As shown in FIG. 3B, the display device 100 includes an insulating layer 171, a conductive layer 172 on the insulating layer 171, an insulating layer 173 on the insulating layer 171 and the conductive layer 172, and an insulating layer 173 on the insulating layer 171 and on the conductive layer 172. and an insulating layer 175 on the insulating layer 174. Insulating layer 171 is provided on a substrate (not shown). Openings reaching the conductive layer 172 are provided in the insulating layer 175, the insulating layer 174, and the insulating layer 173, and a plug 176 is provided so as to fill the opening.

In the pixel portion 177, the light emitting device 130 is provided on the insulating layer 175 and the plug 176. Further, a protective layer 131 is provided to cover the light emitting device 130. A substrate 120 is bonded onto the protective layer 131 with a resin layer 122 . Moreover, it is preferable that an inorganic insulating layer 125 and an insulating layer 127 on the inorganic insulating layer 125 are provided between adjacent light emitting devices 130.

Although a plurality of cross sections of the inorganic insulating layer 125 and the insulating layer 127 are shown in FIG. It is preferable that That is, the inorganic insulating layer 125 and the insulating layer 127 are preferably insulating layers having an opening above the first electrode.

In FIG. 3B, the light emitting devices 130 include a light emitting device 130R, a light emitting device 130G, and a light emitting device 130B. It is assumed that the light emitting device 130R, the light emitting device 130G, and the light emitting device 130B emit light of different colors. For example, light emitting device 130R may emit red light, light emitting device 130G may emit green light, and light emitting device 130B may emit blue light. Further, the light emitting device 130R, the light emitting device 130G, or the light emitting device 130B may emit other visible light or infrared light.

The display device of one embodiment of the present invention can be of a top emission type that emits light in the opposite direction to a substrate on which a light emitting device is formed, for example. Note that the display device of one embodiment of the present invention may be of a bottom emission type.

The light emitting device 130R includes a first electrode (pixel electrode) consisting of a conductive layer 151R and a conductive layer 152R, an EL layer 103R on the first electrode, a common layer 104 on the EL layer 103R, and a pixel electrode on the common layer 104. a second electrode (common electrode) 102. Note that the common layer 104 may or may not be provided, but it is preferable that it is provided because damage to the EL layer 103R during processing can be reduced. When the common layer 104 is provided, the common layer 104 is preferably an electron injection layer.

The light-emitting layer in the light-emitting device 130G has the structure shown in Embodiment 1, and includes a first electrode (pixel electrode) including a conductive layer 151G and a conductive layer 152G, and an EL layer on the first electrode. 103G, a common layer 104 on the EL layer 103G, and a second electrode (common electrode) 102 on the common layer 104. Note that the common layer 104 may or may not be provided, but it is preferable that it is provided because damage to the EL layer 103G during processing can be reduced. When the common layer 104 is provided, the common layer 104 is preferably an electron injection layer. Further, when the common layer 104 is provided, the stacked structure of the EL layer 103G and the common layer 104 corresponds to the EL layer 103 in the first embodiment.

The light emitting device 130B includes a first electrode (pixel electrode) consisting of a conductive layer 151B and a conductive layer 152B, an EL layer 103B on the first electrode, a common layer 104 on the EL layer 103B, and a pixel electrode on the common layer 104. a second electrode (common electrode) 102. Note that the common layer 104 may or may not be provided, but it is preferable that it is provided because damage to the EL layer 103B during processing can be reduced. When the common layer 104 is provided, the common layer 104 is preferably an electron injection layer.

Of the pixel electrode and the common electrode that the light emitting device has, one functions as an anode and the other functions as a cathode. In the following description, unless otherwise specified, the pixel electrode functions as an anode and the common electrode functions as a cathode.

The EL layer 103R, the EL layer 103G, and the EL layer 103B are independent in the form of islands for each emission color. By providing the EL layer 103 in an island shape for each light emitting device 130, leakage current between adjacent light emitting devices 130 can be suppressed even in a high-definition display device. Thereby, crosstalk can be prevented and a display device with extremely high contrast can be realized. In particular, a display device with high current efficiency at low brightness can be realized.

The island-shaped EL layer 103 is formed by depositing an EL film and processing the EL film using a photolithography method.

The EL layer 103 is preferably provided so as to cover the top and side surfaces of the first electrode (pixel electrode) of the light emitting device 130. This makes it easier to increase the aperture ratio of the display device 100 compared to a configuration in which the end of the EL layer 103 is located inside the end of the pixel electrode. Further, by covering the side surface of the pixel electrode of the light emitting device 130 with the EL layer 103, contact between the pixel electrode and the second electrode 102 can be suppressed, so that short circuits of the light emitting device 130 can be suppressed.

Further, in the display device of one embodiment of the present invention, the first electrode (pixel electrode) of the light-emitting device preferably has a stacked structure. For example, in the example shown in FIG. 3B, the first electrode of the light emitting device 130 has a stacked structure of a conductive layer 151 and a conductive layer 152.

For example, a metal material can be used as the conductive layer 151. Specifically, for example, aluminum (Al), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), gallium (Ga). , zinc (Zn), indium (In), tin (Sn), molybdenum (Mo), tantalum (Ta), tungsten (W), palladium (Pd), gold (Au), platinum (Pt), silver (Ag) , yttrium (Y), neodymium (Nd), and alloys containing appropriate combinations of these metals can also be used.

As the conductive layer 152, an oxide containing one or more of indium, tin, zinc, gallium, titanium, aluminum, and silicon can be used. For example, indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, zinc oxide containing gallium, titanium oxide, indium zinc oxide containing gallium, indium zinc oxide containing aluminum, indium tin oxide containing silicon. It is preferable to use a conductive oxide containing one or more of , indium zinc oxide containing silicon, and the like. In particular, indium tin oxide containing silicon has a large work function, for example, a work function of 4.0 eV or more, and therefore can be suitably used as the conductive layer 152.

The conductive layer 151 may have a laminated structure of a plurality of layers having different materials, and the conductive layer 152 may have a laminated structure of a plurality of layers having different materials. In this case, the conductive layer 151 may include a layer made of a material that can be used for the conductive layer 152, such as a conductive oxide, and the conductive layer 152 may be made of a material that can be used for the conductive layer 151, such as a metal material. It may have a layer using a material that can be used. For example, when the conductive layer 151 has a stacked structure of two or more layers, a layer in contact with the conductive layer 152 can be a layer using a material that can be used for the conductive layer 152.

Note that the end portion of the conductive layer 151 preferably has a tapered shape. Specifically, the end portion of the conductive layer 151 preferably has a tapered shape with a taper angle of less than 90°. In this case, the conductive layer 152 provided along the side surface of the conductive layer 151 also has a tapered shape. By tapering the side surface of the conductive layer 152, coverage of the EL layer 103 provided along the side surface of the conductive layer 152 can be improved.

Next, an example of a method for manufacturing the display device 100 having the configuration shown in FIG. 4A will be described with reference to FIGS. 7 to 16.

[Production method example 1]
Thin films (insulating films, semiconductor films, conductive films, etc.) constituting display devices can be formed using sputtering, chemical vapor deposition (CVD), vacuum evaporation, or pulsed laser deposition (PLD). ) method, ALD method, or the like.

In addition, the thin films (insulating films, semiconductor films, conductive films, etc.) that make up the display device can be manufactured using spin coating, dip coating, spray coating, inkjet, dispensing, screen printing, offset printing, doctor knife method, slit coating, and roll coating. It can be formed by a wet film forming method such as , curtain coating, or knife coating.

Furthermore, when processing the thin film that constitutes the display device, it can be processed using, for example, a photolithography method.

In the photolithography method, the light used for exposure can be, for example, i-line (wavelength: 365 nm), g-line (wavelength: 436 nm), h-line (wavelength: 405 nm), or a mixture of these. In addition, ultraviolet rays, KrF laser light, ArF laser light, etc. can also be used. Alternatively, exposure may be performed using immersion exposure technology. Further, as the light used for exposure, extreme ultraviolet (EUV) light or X-rays may be used. Furthermore, an electron beam can be used instead of the light used for exposure.

A dry etching method, a wet etching method, a sandblasting method, or the like can be used for etching the thin film.

First, as shown in FIG. 4A, an insulating layer 171 is formed on a substrate (not shown). Subsequently, a conductive layer 172 and a conductive layer 179 are formed over the insulating layer 171, and an insulating layer 173 is formed over the insulating layer 171 so as to cover the conductive layer 172 and the conductive layer 179. Subsequently, an insulating layer 174 is formed on the insulating layer 173, and an insulating layer 175 is formed on the insulating layer 174.

As the substrate, a substrate having at least enough heat resistance to withstand subsequent heat treatment can be used. For example, semiconductors such as glass substrates, quartz substrates, sapphire substrates, ceramic substrates, organic resin substrates, single crystal semiconductor substrates made of silicon or silicon carbide, polycrystalline semiconductor substrates, compound semiconductor substrates such as silicon germanium, SOI substrates, etc. A substrate can be used.

Subsequently, openings reaching the conductive layer 172 are formed in the insulating layer 175, the insulating layer 174, and the insulating layer 173. Subsequently, a plug 176 is formed so as to fill the opening.

Subsequently, a conductive film 151f, which will later become a conductive layer 151R, a conductive layer 151G, a conductive layer 151B, and a conductive layer 151C, is formed on the plug 176 and the insulating layer 175. For example, a metal material can be used as the conductive film 151f.

Subsequently, a resist mask 191 is formed on the conductive film 151cf. The resist mask 191 can be formed by applying a photosensitive material (photoresist), exposing it to light, and developing it.

Subsequently, as shown in FIG. 4B, for example, the conductive film 151f in a region that does not overlap with the resist mask 191 is removed. As a result, a conductive layer 151 is formed.

Subsequently, as shown in FIG. 4C, the resist mask 191 is removed. The resist mask 191 can be removed, for example, by ashing using oxygen plasma.

Subsequently, as shown in FIG. 4D, an insulating layer 156R, an insulating layer 156G, an insulating layer are formed on the conductive layer 151R, the conductive layer 151G, the conductive layer 151B, the conductive layer 151C, and the insulating layer 175. An insulating film 156f that becomes a layer 156B and an insulating layer 156C is formed.

As the insulating film 156f, an inorganic insulating film such as an oxide insulating film, a nitride insulating film, an oxynitride insulating film, or a nitride oxide insulating film, for example, silicon oxynitride can be used.

Subsequently, as shown in FIG. 4E, the insulating film 156f is processed to form an insulating layer 156R, an insulating layer 156G, an insulating layer 156B, and an insulating layer 156C.

Subsequently, as shown in FIG. 5A, the conductive layer 151R, the conductive layer 151G, the conductive layer 151B, the conductive layer 151C, the insulating layer 156R, the insulating layer 156G, the insulating layer 156B, and the insulating layer A conductive film 152f is formed on the insulating layer 156C and the insulating layer 175. For example, a conductive oxide can be used as the conductive film 152f. The conductive film 152f may be laminated.

Subsequently, as shown in FIG. 5B, the conductive film 152f is processed to form a conductive layer 152R, a conductive layer 152G, a conductive layer 152B, and a conductive layer 152C.

Subsequently, as shown in FIG. 5C, an EL film 103Rf is formed over the conductive layer 152R, the conductive layer 152G, the conductive layer 152B, and the insulating layer 175. Note that, as shown in FIG. 5C, the EL film 103Rf is not formed on the conductive layer 152C.

Subsequently, as shown in FIG. 5C, a sacrificial film 158f and a mask film 159Rf are formed.

By providing the sacrificial film 158Rf over the EL film 103Rf, damage to the EL film 103Rf during the manufacturing process of a display device can be reduced, and the reliability of the light-emitting device can be improved.

As the sacrificial film 158Rf, a film having high resistance to the processing conditions of the EL film 103Rf, specifically, a film having a high etching selectivity with respect to the EL film 103Rf is used. For the mask film 159Rf, a film having a high etching selectivity with respect to the sacrificial film 158Rf is used.

Further, the sacrificial film 158Rf and the mask film 159Rf are formed at a temperature lower than the allowable temperature limit of the EL film 103Rf. The substrate temperature when forming the sacrificial film 158Rf and the mask film 159Rf is typically 200°C or lower, preferably 150°C or lower, more preferably 120°C or lower, more preferably 100°C or lower, and even more preferably is below 80°C.

It is preferable to use films that can be removed by wet etching as the sacrificial film 158Rf and the mask film 159Rf.

Note that the sacrificial film 158Rf formed in contact with the EL film 103Rf is preferably formed using a formation method that causes less damage to the EL film 103Rf than the mask film 159Rf. For example, ALD method or vacuum evaporation method is preferable to sputtering method.

As the sacrificial film 158Rf and the mask film 159Rf, for example, one or more of a metal film, an alloy film, a metal oxide film, a semiconductor film, an organic insulating film, an inorganic insulating film, etc. can be used.

The sacrificial film 158Rf and the mask film 159Rf each contain, for example, gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, tantalum, or the like. A metal material or an alloy material containing the metal material can be used. In particular, it is preferable to use a low melting point material such as aluminum or silver. By using a metal material capable of blocking ultraviolet rays for one or both of the sacrificial film 158Rf and the mask film 159Rf, irradiation of the EL film 103Rf with ultraviolet rays can be suppressed, and deterioration of the EL film 103Rf can be suppressed. ,preferable.

In addition, the sacrificial film 158Rf and the mask film 159Rf contain In-Ga-Zn oxide, indium oxide, In-Zn oxide, In-Sn oxide, indium titanium oxide (In-Ti oxide), and indium titanium oxide, respectively. Contains tin zinc oxide (In-Sn-Zn oxide), indium titanium zinc oxide (In-Ti-Zn oxide), indium gallium tin zinc oxide (In-Ga-Sn-Zn oxide), silicon Metal oxides such as indium tin oxide can be used.

In addition, in place of gallium in the above metal oxide, element M (M is aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium) , tantalum, tungsten, or magnesium).

As the sacrificial film 158Rf and the mask film 159Rf, it is preferable to use a semiconductor material such as silicon or germanium because it has high affinity with the semiconductor manufacturing process. Alternatively, a compound containing the above semiconductor material can be used.

Moreover, various inorganic insulating films can be used as the sacrificial film 158Rf and the mask film 159Rf, respectively. In particular, an oxide insulating film is preferable because it has higher adhesion to the EL film 103Rf than a nitride insulating film.

Subsequently, as shown in FIG. 5C, a resist mask 190R is formed. The resist mask 190R can be formed by applying a photosensitive material (photoresist), exposing it to light, and developing it.

The resist mask 190R is provided at a position overlapping the conductive layer 152R. It is preferable that the resist mask 190R is also provided at a position overlapping the conductive layer 152C. This can prevent the conductive layer 152C from being damaged during the manufacturing process of the display device.

Subsequently, as shown in FIG. 5D, a portion of the mask film 159Rf is removed using a resist mask 190R to form a mask layer 159R. The mask layer 159R remains on the conductive layer 152R and the conductive layer 152C. After that, the resist mask 190R is removed. Subsequently, using the mask layer 159R as a mask (also referred to as a hard mask), a portion of the sacrificial film 158Rf is removed to form a sacrificial layer 158R.

By using the wet etching method, damage to the EL film 103Rf can be reduced when processing the sacrificial film 158Rf and the mask film 159Rf, compared to the case where the dry etching method is used. When using the wet etching method, for example, a developer, aqueous tetramethylammonium hydroxide solution (TMAH), dilute hydrofluoric acid, oxalic acid, phosphoric acid, acetic acid, nitric acid, or a chemical solution using a mixed liquid thereof may be used. preferable.

Furthermore, when dry etching is used to process the sacrificial film 158Rf, deterioration of the EL film 103Rf can be suppressed by not using a gas containing oxygen as the etching gas.

The resist mask 190R can be removed in the same manner as the resist mask 191.

Subsequently, as shown in FIG. 5(D), the EL film 103Rf is processed to form an EL layer 103R. For example, using the mask layer 159R and sacrificial layer 158R as hard masks, a portion of the EL film 103Rf is removed to form the EL layer 103R.

As a result, as shown in FIG. 5D, the stacked structure of the EL layer 103R, sacrificial layer 158R, and mask layer 159R remains on the conductive layer 152R. Further, the conductive layer 152G and the conductive layer 152B are exposed.

The EL film 103Rf is preferably processed by anisotropic etching. In particular, anisotropic dry etching is preferred. Alternatively, wet etching may be used.

When dry etching is used, deterioration of the EL film 103Rf can be suppressed by not using a gas containing oxygen as the etching gas.

Further, a gas containing oxygen may be used as the etching gas. When the etching gas contains oxygen, the etching speed can be increased. Therefore, etching can be performed under low power conditions while maintaining a sufficient etching rate. Therefore, damage to the EL film 103Rf can be suppressed. Furthermore, problems such as adhesion of reaction products that occur during etching can be suppressed.

When using the dry etching method, for example, one of _H2 , _CF4 , _C4F8 , _SF6 , _CHF3 , _Cl2 , _H2O , _BCl3 , or Group 18 elements such as He, _Ar , etc. It is preferable to use a gas containing the above as an etching gas. Alternatively, it is preferable to use a gas containing one or more of these and oxygen as the etching gas. Alternatively, oxygen gas may be used as the etching gas.

Subsequently, as shown in FIG. 6A, an EL film 103Gf that will later become the EL layer 103G is formed.

The EL film 103Gf can be formed by a method similar to the method that can be used to form the EL film 103Rf. Further, the EL film 103Gf can have the same configuration as the EL film 103Rf.

Subsequently, a sacrificial film 158Gf and a mask film 159Gf are formed in this order. After that, a resist mask 190G is formed at a position overlapping the conductive layer 152G. The materials and formation method of the sacrificial film 158Gf and the mask film 159Gf are the same as the conditions applicable to the sacrificial film 158Rf and the mask film 159Rf. The material and formation method of the resist mask 190G are similar to the conditions applicable to the resist mask 190R.

Subsequently, as shown in FIG. 6B, a portion of the mask film 159Gf is removed using a resist mask 190G to form a mask layer 159G. Mask layer 159G remains on conductive layer 152G. After that, the resist mask 190G is removed. Subsequently, using the mask layer 159G as a mask, a portion of the sacrificial film 158Gf is removed to form a sacrificial layer 158G. Subsequently, the EL film 103Gf is processed to form an EL layer 103G.

Subsequently, as shown in FIG. 6C, an EL film 103Bf is formed. The EL film 103Bf can be formed by a method similar to the method that can be used to form the EL film 103Rf. Furthermore, the EL film 103Bf can have the same configuration as the EL film 103Rf.

Subsequently, as shown in FIG. 6C, a sacrificial film 158Bf and a mask film 159Bf are sequentially formed. After that, a resist mask 190B is formed at a position overlapping the conductive layer 152B. The materials and formation method of the sacrificial film 158Bf and the mask film 159Bf are the same as the conditions applicable to the sacrificial film 158Rf and the mask film 159Rf. The material and formation method of resist mask 190B are similar to the conditions applicable to resist mask 190R.

Subsequently, as shown in FIG. 6D, a portion of the mask film 159Bf is removed using a resist mask 190B to form a mask layer 159B. Mask layer 159B remains on conductive layer 152B. After that, resist mask 190B is removed. Subsequently, using the mask layer 159B as a mask, a portion of the sacrificial film 158Bf is removed to form a sacrificial layer 158B. Subsequently, the EL film 103Bf is processed to form an EL layer 103B. For example, using the mask layer 159B and the sacrificial layer 158B as hard masks, a portion of the EL film 103Bf is removed to form the EL layer 103B.

As a result, the laminated structure of the EL layer 103B, the sacrificial layer 158B, and the mask layer 159B remains on the conductive layer 152B. Further, the mask layer 159R and the mask layer 159G are exposed.

Note that the side surfaces of the EL layer 103R, EL layer 103G, and EL layer 103B are preferably perpendicular or approximately perpendicular to the surface on which they are formed. For example, it is preferable that the angle between the surface to be formed and these side surfaces be 60 degrees or more and 90 degrees or less.

As described above, the distance between two adjacent EL layers 103R, 103G, and 103B formed using the photolithography method is 8 μm or less, 5 μm or less, 3 μm or less, 2 μm or less, or It can be narrowed down to 1 μm or less. Here, the distance can be defined as, for example, the distance between two adjacent opposing ends of the EL layer 103R, EL layer 103G, and EL layer 103B. In this way, by narrowing the distance between the island-shaped organic compound layers, a display device with high definition and a large aperture ratio can be provided. Further, the distance between the first electrodes between adjacent light emitting devices can also be narrowed, for example, to 10 μm or less, 8 μm or less, 5 μm or less, 3 μm or less, or 2 μm or less. Note that the distance between the first electrodes between adjacent light emitting devices is preferably 2 μm or more and 5 μm or less.

Subsequently, as shown in FIG. 7A, the mask layer 159R, the mask layer 159G, and the mask layer 159B are preferably removed.

For the mask layer removal step, a method similar to the mask layer processing step can be used. In particular, by using the wet etching method, damage to the EL layer 103 when removing the mask layer can be reduced compared to when using the dry etching method.

Alternatively, the mask layer may be removed by dissolving it in a solvent such as water or alcohol. Examples of the alcohol include ethyl alcohol, methyl alcohol, isopropyl alcohol (IPA), and glycerin.

After removing the mask layer, a drying process may be performed to remove water adsorbed on the surface. For example, heat treatment can be performed under an inert gas atmosphere or a reduced pressure atmosphere. The heat treatment can be performed at a substrate temperature of 50°C or higher and 200°C or lower, preferably 60°C or higher and 150°C or lower, and more preferably 70°C or higher and 120°C or lower. A reduced pressure atmosphere is preferable because drying can be performed at a lower temperature.

Subsequently, as shown in FIG. 7(B), an inorganic insulating film 125f is formed.

Subsequently, as shown in FIG. 7C, an insulating film 127f that will later become the insulating layer 127 is formed on the inorganic insulating film 125f.

The substrate temperature when forming the inorganic insulating film 125f and the insulating film 127f is 60°C or higher, 80°C or higher, 100°C or higher, or 120°C or higher and 200°C or lower, 180°C or lower, or 160°C, respectively. Hereinafter, the temperature is preferably 150°C or lower, or 140°C or lower.

As the inorganic insulating film 125f, an insulating film having a thickness of 3 nm or more, 5 nm or more, or 10 nm or more and 200 nm or less, 150 nm or less, 100 nm or less, or 50 nm or less is formed within the above substrate temperature range. It is preferable.

The inorganic insulating film 125f is preferably formed using, for example, an ALD method. It is preferable to use the ALD method because damage to the film can be reduced and a film with high coverage can be formed. As the inorganic insulating film 125f, it is preferable to form an aluminum oxide film using, for example, an ALD method.

The insulating film 127f is preferably formed using the wet film forming method described above. The insulating film 127f is preferably formed using a photosensitive material by spin coating, for example, and more specifically, it is preferably formed using a photosensitive resin composition containing an acrylic resin.

Subsequently, exposure is performed to expose a portion of the insulating film 127f to visible light or ultraviolet light. The insulating layer 127 is formed in a region sandwiched between any two of the conductive layer 152R, the conductive layer 152G, and the conductive layer 152B, and around the conductive layer 152C.

The width of the insulating layer 127 to be formed later can be controlled by the exposed area of the insulating film 127f. In this embodiment, the insulating layer 127 is processed so as to have a portion overlapping the upper surface of the conductive layer 151.

The light used for exposure preferably includes i-line (wavelength: 365 nm). Further, the light used for exposure may include at least one of the g-line (wavelength: 436 nm) and the h-line (wavelength: 405 nm).

Subsequently, as shown in FIG. 8A, development is performed to remove the exposed region of the insulating film 127f and form an insulating layer 127a.

Subsequently, as shown in FIG. 8B, etching is performed using the insulating layer 127a as a mask to remove a part of the inorganic insulating film 125f, and to remove the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B. Reduce some film thickness. As a result, an inorganic insulating layer 125 is formed under the insulating layer 127a. Further, the surfaces of the thinner portions of the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B are exposed. Note that, hereinafter, the etching process using the insulating layer 127a as a mask may be referred to as a first etching process.

The first etching process can be performed by dry etching or wet etching. Note that it is preferable that the inorganic insulating film 125f is formed using the same material as the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B because the first etching process can be performed all at once.

When performing dry etching, it is preferable to use a chlorine-based gas. As the chlorine-based gas, Cl ₂ , BCl ₃ , SiCl ₄ , CCl ₄ , etc. can be used alone or in a mixture of two or more gases. Furthermore, oxygen gas, hydrogen gas, helium gas, argon gas, and the like can be appropriately added to the chlorine-based gas alone or in a mixture of two or more gases. By using dry etching, thin regions of the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B can be formed with good in-plane uniformity.

As the dry etching apparatus, a dry etching apparatus having a high-density plasma source can be used. As the dry etching apparatus having a high-density plasma source, for example, an inductively coupled plasma (ICP) etching apparatus can be used. Alternatively, a capacitively coupled plasma (CCP) etching apparatus having parallel plate electrodes can be used.

Further, it is preferable that the first etching process is performed by wet etching. By using the wet etching method, damage to the EL layer 103R, EL layer 103G, and EL layer 103B can be reduced compared to when using the dry etching method. For example, wet etching can be performed using an alkaline or acid solution.

In the first etching process, it is preferable that the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B are not completely removed, and that the etching process is stopped when the film thickness is reduced. In this way, by leaving the corresponding sacrificial layers 158R, 158G, and 158B on the EL layers 103R, 103G, and 103B, the EL layers can be 103R, the EL layer 103G, and the EL layer 103B can be prevented from being damaged.

Subsequently, it is preferable that the entire substrate is exposed to light and the insulating layer 127a is irradiated with visible light or ultraviolet light. The energy density of the exposure is preferably greater than 0 mJ/cm ² and less than 800 mJ/cm ² , more preferably greater than 0 mJ/cm ² and less than 500 mJ/cm ² . By performing such exposure after development, the transparency of the insulating layer 127a may be improved. In addition, it may be possible to lower the substrate temperature required for heat treatment to transform the insulating layer 127a into a tapered shape in a later step.

Here, the presence of a barrier insulating layer against oxygen (for example, an aluminum oxide film, etc.) as the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B allows the EL layer 103R, EL layer 103G, and EL layer 103B to be exposed to oxygen. can reduce the spread of

Subsequently, heat treatment (also referred to as post-bake) is performed. By performing the heat treatment, the insulating layer 127a can be transformed into the insulating layer 127 having a tapered side surface (FIG. 8C). The heat treatment is performed at a temperature lower than the allowable temperature limit of the organic compound layer. The heat treatment can be performed at a substrate temperature of 50°C or more and 200°C or less, preferably 60°C or more and 150°C or less, and more preferably 70°C or more and 130°C or less. The heating atmosphere may be an air atmosphere or an inert gas atmosphere. Further, the heating atmosphere may be an atmospheric pressure atmosphere or a reduced pressure atmosphere. Thereby, the adhesion between the insulating layer 127 and the inorganic insulating layer 125 can be improved, and the corrosion resistance of the insulating layer 127 can also be improved.

In the first etching process, the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B are not completely removed, but the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B remain in a state where the film thickness is reduced. By doing so, it is possible to prevent the EL layer 103R, EL layer 103G, and EL layer 103B from being damaged and deteriorating during the heat treatment. Therefore, the reliability of the light emitting device can be improved.

Subsequently, as shown in FIG. 9A, etching is performed using the insulating layer 127 as a mask to remove parts of the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B. As a result, openings are formed in each of the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B, and the upper surfaces of the EL layer 103R, EL layer 103G, EL layer 103B, and conductive layer 152C are exposed. Note that, hereinafter, this etching process may be referred to as a second etching process.

The ends of the inorganic insulating layer 125 are covered with an insulating layer 127. In addition, in FIG. 9A, the insulating layer 127 covers a part of the end of the sacrificial layer 158G (specifically, the tapered part formed by the first etching process), and the second etching process An example is shown in which the tapered portion formed by is exposed.

The second etching process is performed by wet etching. By using the wet etching method, damage to the EL layer 103R, EL layer 103G, and EL layer 103B can be reduced compared to when using the dry etching method. Wet etching can be performed using, for example, an alkaline solution or an acidic solution.

Subsequently, as shown in FIG. 9B, a common electrode 155 is formed on the EL layer 103R, the EL layer 103G, the EL layer 103B, the conductive layer 152C, and the insulating layer 127. The common electrode 155 can be formed by a method such as a sputtering method or a vacuum evaporation method.

Subsequently, as shown in FIG. 9C, a protective layer 131 is formed on the common electrode 155. The protective layer 131 can be formed by a method such as a vacuum evaporation method, a sputtering method, a CVD method, or an ALD method.

Subsequently, a display device can be manufactured by bonding the substrate 120 onto the protective layer 131 using the resin layer 122. As described above, in the method for manufacturing a display device of one embodiment of the present invention, the insulating layer 156 is provided so as to have a region overlapping with the side surface of the conductive layer 151, and the conductive layer 156 is provided so as to cover the conductive layer 151 and the insulating layer 156. 152 is formed. This can increase the yield of display devices and suppress the occurrence of defects.

As described above, in the method for manufacturing a display device in this embodiment, the island-shaped EL layer 103R, the island-shaped EL layer 103G, and the EL layer 103B are not formed using a fine metal mask. Since it is formed by forming a film over one surface and then processing it using a photolithography method, it is possible to form an island-shaped layer with a uniform thickness. Further, a high-definition display device or a display device with a high aperture ratio can be realized. Furthermore, even if the definition or aperture ratio is high and the distance between subpixels is extremely short, it is possible to prevent the EL layer 103R, EL layer 103G, and EL layer 103B from coming into contact with each other in adjacent subpixels. Therefore, generation of leakage current between subpixels can be suppressed. Thereby, crosstalk can be prevented and a display device with extremely high contrast can be realized. Further, even if the display device includes tandem light-emitting devices manufactured using a photolithography method, a display device with good characteristics can be provided.

(Embodiment 4)
In this embodiment, a display device that is one embodiment of the present invention will be described.

The display device of this embodiment can be a high-definition display device. Therefore, the display device of this embodiment can be used, for example, in the display section of information terminals (wearable devices) such as wristwatch-type and bracelet-type devices, VR devices such as head-mounted displays (HMD), and glasses. It can be used in the display section of wearable devices that can be worn on the head, such as AR devices.

Further, the display device of this embodiment can be a high-resolution display device or a large-sized display device. Therefore, the display device of this embodiment can be used for, for example, relatively large screens such as television devices, desktop or notebook personal computers, computer monitors, digital signage, and large game machines such as pachinko machines. In addition to electronic devices including electronic devices, the present invention can be used in display units of digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, personal digital assistants, and sound reproduction devices.

[Display module]
FIG. 10(A) shows a perspective view of the display module 280. The display module 280 includes a display device 100A and an FPC 290. Note that the display device included in the display module 280 is not limited to the display device 100A, and may be any one of the display devices 100B to 100E described later.

Display module 280 has a substrate 291 and a substrate 292. The display module 280 has a display section 281. The display section 281 is an area in the display module 280 that displays images, and is an area where light from each pixel provided in a pixel section 284, which will be described later, can be visually recognized.

FIG. 10B is a perspective view schematically showing the structure of the substrate 291 side. On the substrate 291, a circuit section 282, a pixel circuit section 283 on the circuit section 282, and a pixel section 284 on the pixel circuit section 283 are stacked. Further, a terminal portion 285 for connecting to the FPC 290 is provided in a portion of the substrate 291 that does not overlap with the pixel portion 284. The terminal section 285 and the circuit section 282 are electrically connected by a wiring section 286 made up of a plurality of wires.

The pixel section 284 includes a plurality of pixels 284a arranged periodically. An enlarged view of one pixel 284a is shown on the right side of FIG. 10(B). The various configurations described in the previous embodiments can be applied to the pixel 284a.

The pixel circuit section 283 includes a plurality of pixel circuits 283a arranged periodically.

One pixel circuit 283a is a circuit that controls driving of a plurality of elements included in one pixel 284a.

The circuit section 282 has a circuit that drives each pixel circuit 283a of the pixel circuit section 283. For example, it is preferable to have one or both of a gate line drive circuit and a source line drive circuit. In addition, it may include at least one of an arithmetic circuit, a memory circuit, a power supply circuit, and the like.

The FPC 290 functions as a wiring for supplying a video signal, a power supply potential, etc. to the circuit section 282 from the outside. Further, an IC may be mounted on the FPC 290.

Since the display module 280 can have a structure in which one or both of the pixel circuit section 283 and the circuit section 282 are stacked on the lower side of the pixel section 284, the aperture ratio (effective display area ratio) of the display section 281 can be extremely high. It can be made higher.

Since such a display module 280 has extremely high definition, it can be suitably used for VR equipment such as an HMD or glasses-type AR equipment. For example, even if the display section of the display module 280 is configured to be visible through a lens, the display module 280 has an extremely high-definition display section 281, so even if the display section is enlarged with a lens, the pixels will not be visible. , it is possible to perform a highly immersive display. Furthermore, the display module 280 is not limited to this, and can be suitably used in electronic equipment having a relatively small display section.

[Display device 100A]
The display device 100A illustrated in FIG. 11A includes a substrate 301, a light-emitting device 130R, a light-emitting device 130G, a light-emitting device 130B, a capacitor 240, and a transistor 310.

The substrate 301 corresponds to the substrate 291 in FIGS. 10(A) and 10(B). The transistor 310 is a transistor that has a channel formation region in the substrate 301. As the substrate 301, for example, a semiconductor substrate such as a single crystal silicon substrate can be used. The transistor 310 includes a portion of a substrate 301, a conductive layer 311, a low resistance region 312, an insulating layer 313, and an insulating layer 314. The conductive layer 311 functions as a gate electrode. The insulating layer 313 is located between the substrate 301 and the conductive layer 311 and functions as a gate insulating layer. The low resistance region 312 is a region in which the substrate 301 is doped with impurities, and functions as a source or a drain. The insulating layer 314 is provided to cover the side surface of the conductive layer 311.

Furthermore, an element isolation layer 315 is provided between two adjacent transistors 310 so as to be embedded in the substrate 301 .

Further, an insulating layer 261 is provided to cover the transistor 310, and a capacitor 240 is provided on the insulating layer 261.

Capacitor 240 includes a conductive layer 241, a conductive layer 245, and an insulating layer 243 located between them. The conductive layer 241 functions as one electrode of the capacitor 240, the conductive layer 245 functions as the other electrode of the capacitor 240, and the insulating layer 243 functions as a dielectric of the capacitor 240.

The conductive layer 241 is provided on the insulating layer 261 and embedded in the insulating layer 254. The conductive layer 241 is electrically connected to one of the source and drain of the transistor 310 by a plug 271 embedded in the insulating layer 261. An insulating layer 243 is provided to cover the conductive layer 241. The conductive layer 245 is provided in a region overlapping with the conductive layer 241 with the insulating layer 243 interposed therebetween.

An insulating layer 255 is provided to cover the capacitor 240 , an insulating layer 174 is provided on the insulating layer 255 , and an insulating layer 175 is provided on the insulating layer 174 . A light emitting device 130R, a light emitting device 130G, and a light emitting device 130B are provided on the insulating layer 175. An insulator is provided in the region between adjacent light emitting devices.

An insulating layer 156R is provided to have a region that overlaps with the side surface of the conductive layer 151R, an insulating layer 156G is provided to have a region that overlaps with the side surface of the conductive layer 151G, and a region that overlaps with the side surface of the conductive layer 151B. An insulating layer 156B is provided. Further, a conductive layer 152R is provided to cover the conductive layer 151R and the insulating layer 156R, a conductive layer 152G is provided to cover the conductive layer 151G and the insulating layer 156G, and a conductive layer 152G is provided to cover the conductive layer 151B and the insulating layer 156B. A layer 152B is provided. A sacrificial layer 158R is located on the EL layer 103R, a sacrificial layer 158G is located on the EL layer 103G, and a sacrificial layer 158B is located on the EL layer 103B.

The conductive layer 151R, the conductive layer 151G, and the conductive layer 151B include an insulating layer 243, an insulating layer 255, an insulating layer 174, a plug 256 embedded in the insulating layer 175, a conductive layer 241 embedded in the insulating layer 254, and It is electrically connected to one of the source and drain of the transistor 310 by a plug 271 embedded in the insulating layer 261. Various conductive materials can be used for the plug.

Further, a protective layer 131 is provided on the light emitting device 130R, the light emitting device 130G, and the light emitting device 130B. A substrate 120 is bonded onto the protective layer 131 with a resin layer 122 . For details about the components from the light emitting device 130 to the substrate 120, Embodiment 2 can be referred to. The substrate 120 corresponds to the substrate 292 in FIG. 10(A).

FIG. 11(B) is a modification of the display device 100A shown in FIG. 11(A). The display device shown in FIG. 11B includes a colored layer 132R, a colored layer 132G, and a colored layer 132B, and a region where the light emitting device 130 overlaps with one of the colored layer 132R, colored layer 132G, and colored layer 132B. have In the display device shown in FIG. 11B, the light-emitting device 130 can emit, for example, white light. Further, for example, the colored layer 132R can transmit red light, the colored layer 132G can transmit green light, and the colored layer 132B can transmit blue light.

[Display device 100B]
FIG. 12 shows a perspective view of the display device 100B, and FIG. 13 shows a cross-sectional view of the display device 100B.

The display device 100B has a configuration in which a substrate 352 and a substrate 351 are bonded together. In FIG. 12, the substrate 352 is indicated by a broken line.

The display device 100B includes a pixel portion 177, a connection portion 140, a circuit 356, wiring 355, and the like. FIG. 12 shows an example in which an IC 354 and an FPC 353 are mounted on the display device 100B. Therefore, the configuration shown in FIG. 12 can also be called a display module that includes the display device 100B, an IC (integrated circuit), and an FPC. Here, a device in which a connector such as an FPC is attached to a substrate of a display device, or a device in which an IC is mounted on the substrate is referred to as a display module.

The connection section 140 is provided outside the pixel section 177. The connecting portion 140 may be singular or plural. The common electrode of the light emitting device and the conductive layer are electrically connected to the connection part 140, and a potential can be supplied to the common electrode.

As the circuit 356, for example, a scanning line driver circuit can be used.

The wiring 355 has a function of supplying signals and power to the pixel portion 177 and the circuit 356. The signal and power are input from the outside via the FPC 353 or from the IC 354 to the wiring 355.

FIG. 12 shows an example in which an IC 354 is provided on a substrate 351 by a COG (Chip On Glass) method, a COF (Chip On Film) method, or the like. As the IC 354, an IC having, for example, a scanning line driver circuit or a signal line driver circuit can be applied. Note that the display device 100B and the display module may have a configuration in which no IC is provided. Further, the IC may be mounted on an FPC using, for example, a COF method.

In FIG. 13, a part of the area including the FPC 353, a part of the circuit 356, a part of the pixel part 177, a part of the connection part 140, and a part of the area including the end of the display device 100B are cut out. An example of the cross section is shown below.

[Display device 100C]
A display device 100C shown in FIG. 13 includes, between a substrate 351 and a substrate 352, a transistor 201, a transistor 205, a light emitting device 130R that emits red light, a light emitting device 130G that emits green light, and a light emitting device that emits blue light. It has a device 130B and the like.

Embodiment 1 can be referred to for details of the light emitting device 130R, the light emitting device 130G, and the light emitting device 130B.

The light emitting device 130R includes a conductive layer 224R, a conductive layer 151R on the conductive layer 224R, and a conductive layer 152R on the conductive layer 151R. The light emitting device 130G includes a conductive layer 224G, a conductive layer 151G on the conductive layer 224G, and a conductive layer 152G on the conductive layer 151G. Light emitting device 130B includes conductive layer 224B, conductive layer 151B on conductive layer 224B, and conductive layer 152B on conductive layer 151B.

The conductive layer 224R is connected to the conductive layer 222b of the transistor 205 through an opening provided in the insulating layer 214. The end of the conductive layer 151R is located outside the end of the conductive layer 224R. An insulating layer 156R is provided to have a region in contact with the side surface of the conductive layer 151R, and a conductive layer 152R is provided to cover the conductive layer 151R and the insulating layer 156R.

Regarding the conductive layer 224G, conductive layer 151G, conductive layer 152G, and insulating layer 156G in the light emitting device 130G, and the conductive layer 224B, conductive layer 151B, conductive layer 152B, and insulating layer 156B in the light emitting device 130B, the conductive layer 224R in the light emitting device 130R , the conductive layer 151R, the conductive layer 152R, and the insulating layer 156R, detailed description thereof will be omitted.

Recesses are formed in the conductive layer 224R, the conductive layer 224G, and the conductive layer 224B so as to cover the opening provided in the insulating layer 214. A layer 128 is embedded in the recess.

The layer 128 has a function of flattening the recessed portions of the conductive layer 224R, the conductive layer 224G, and the conductive layer 224B. On the conductive layer 224R, the conductive layer 224G, the conductive layer 224B, and the layer 128, the conductive layer 151R, the conductive layer 151G, and the conductive layer 151B are electrically connected to the conductive layer 224R, the conductive layer 224G, and the conductive layer 224B. It is provided. Therefore, the regions of the conductive layer 224R, the conductive layer 224G, and the conductive layer 224B that overlap with the recesses can also be used as light emitting regions, and the aperture ratio of the pixel can be increased.

Layer 128 may be an insulating layer or a conductive layer. For the layer 128, various inorganic insulating materials, organic insulating materials, and conductive materials can be used as appropriate. In particular, layer 128 is preferably formed using an insulating material, and particularly preferably formed using an organic insulating material. For example, an organic insulating material that can be used for the above-described insulating layer 127 can be applied to the layer 128.

A protective layer 131 is provided on the light emitting device 130R, the light emitting device 130G, and the light emitting device 130B. The protective layer 131 and the substrate 352 are bonded together via an adhesive layer 142. A light shielding layer 157 is provided on the substrate 352. For sealing the light emitting device 130, a solid sealing structure, a hollow sealing structure, or the like can be applied. In FIG. 13, the space between substrate 352 and substrate 351 is filled with adhesive layer 142, and a solid sealing structure is applied. Alternatively, the space may be filled with an inert gas (nitrogen, argon, etc.) and a hollow sealing structure may be applied. At this time, the adhesive layer 142 may be provided so as not to overlap the light emitting device. Further, the space may be filled with a resin different from that of the adhesive layer 142 provided in a frame shape.

In FIG. 13, the connection portion 140 includes a conductive layer 224C obtained by processing the same conductive film as the conductive layer 224R, the conductive layer 224G, and the conductive layer 224B, the conductive layer 151R, the conductive layer 151G, and the conductive layer 151B. An example including a conductive layer 151C obtained by processing the same conductive film as the conductive layer 152R, the conductive layer 152G, and the conductive layer 152C obtained by processing the same conductive film as the conductive layer 152B. It shows. Further, FIG. 13 shows an example in which the insulating layer 156C is provided so as to have a region overlapping with the side surface of the conductive layer 151C.

The display device 100B is a top emission type. Light emitted by the light emitting device is emitted to the substrate 352 side. The substrate 352 is preferably made of a material that is highly transparent to visible light. The pixel electrode includes a material that reflects visible light, and the counter electrode (common electrode 155) includes a material that transmits visible light.

On the substrate 351, an insulating layer 211, an insulating layer 213, an insulating layer 215, and an insulating layer 214 are provided in this order. A part of the insulating layer 211 functions as a gate insulating layer of each transistor. A portion of the insulating layer 213 functions as a gate insulating layer of each transistor. An insulating layer 215 is provided to cover the transistor. The insulating layer 214 is provided to cover the transistor and functions as a planarization layer. Note that the number of gate insulating layers and the number of insulating layers covering the transistor are not limited, and each may be a single layer or two or more layers.

It is preferable to use an inorganic insulating film as each of the insulating layer 211, the insulating layer 213, and the insulating layer 215.

An organic insulating layer is suitable for the insulating layer 214 that functions as a planarization layer.

The transistors 201 and 205 include a conductive layer 221 functioning as a gate, an insulating layer 211 functioning as a gate insulating layer, a conductive layer 222a and a conductive layer 222b functioning as a source and a drain, a semiconductor layer 231, and an insulating layer 221 functioning as a gate insulating layer. It has a layer 213 and a conductive layer 223 that functions as a gate.

A connecting portion 204 is provided in a region of the substrate 351 where the substrate 352 does not overlap. In the connection portion 204, the wiring 355 is electrically connected to the FPC 353 via the conductive layer 166 and the connection layer 242. The conductive layer 166 is a conductive film obtained by processing the same conductive film as the conductive layer 224R, the conductive layer 224G, and the conductive layer 224B, and the same conductive film as the conductive layer 151R, the conductive layer 151G, and the conductive layer 151B. An example of a stacked structure of a conductive film obtained by processing a conductive film and a conductive film obtained by processing the same conductive film as the conductive layer 152R, conductive layer 152G, and conductive layer 152B will be shown. The conductive layer 166 is exposed on the upper surface of the connection portion 204. Thereby, the connecting portion 204 and the FPC 353 can be electrically connected via the connecting layer 242.

It is preferable to provide a light shielding layer 157 on the surface of the substrate 352 on the substrate 351 side. The light shielding layer 157 can be provided between adjacent light emitting devices, at the connection portion 140, the circuit 356, and the like. Further, various optical members can be arranged outside the substrate 352.

Materials that can be used for the substrate 120 can be used as the substrate 351 and the substrate 352, respectively.

As the adhesive layer 142, a material that can be used for the resin layer 122 can be used.

As the connection layer 242, an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), or the like can be used.

[Display device 100D]
The display device 100D shown in FIG. 14 is mainly different from the display device 100A shown in FIG. 13 in that it is a bottom emission type display device.

Light emitted by the light emitting device is emitted toward the substrate 351 side. The substrate 351 is preferably made of a material that is highly transparent to visible light. On the other hand, the light transmittance of the material used for the substrate 352 does not matter.

A light blocking layer 317 is preferably formed between the substrate 351 and the transistor 201 and between the substrate 351 and the transistor 205. FIG. 14 shows an example in which a light shielding layer 317 is provided over a substrate 351, an insulating layer 153 is provided over the light shielding layer 317, and transistors 201, 205, etc. are provided over the insulating layer 153.

The light emitting device 130R includes a conductive layer 112R, a conductive layer 126R on the conductive layer 112R, and a conductive layer 129R on the conductive layer 126R.

Light emitting device 130B includes conductive layer 112B, conductive layer 126B on conductive layer 112B, and conductive layer 129B on conductive layer 126B.

The conductive layers 112R, 112B, 126R, 126B, 129R, and 129B are each made of a material that is highly transparent to visible light. It is preferable to use a material that reflects visible light for the second electrode 102.

Although the light emitting device 130G is not illustrated in FIG. 14, the light emitting device 130G is also provided.

Further, although FIG. 14 and the like show an example in which the upper surface of the layer 128 has a flat portion, the shape of the layer 128 is not particularly limited.

[Display device 100E]
The display device 100E shown in FIG. 15 is a modification of the display device 100B shown in FIG. 13, and is mainly different from the display device 100B in that it includes a colored layer 132R, a colored layer 132G, and a colored layer 132B.

In the display device 100E, the light emitting device 130 has a region overlapping with one of the colored layer 132R, the colored layer 132G, and the colored layer 132B. The colored layer 132R, the colored layer 132G, and the colored layer 132B can be provided on the surface of the substrate 352 on the substrate 351 side. The end of the colored layer 132R, the end of the colored layer 132G, and the end of the colored layer 132B can be overlapped with the light shielding layer 157.

In the display device 100E, the light emitting device 130 can emit white light, for example. Further, for example, the colored layer 132R can transmit red light, the colored layer 132G can transmit green light, and the colored layer 132B can transmit blue light. Note that the display device 100E may have a configuration in which a colored layer 132R, a colored layer 132G, and a colored layer 132B are provided between the protective layer 131 and the adhesive layer 142.

This embodiment mode can be combined with other embodiment modes or examples as appropriate. Further, in this specification, when a plurality of configuration examples are shown in one embodiment, the configuration examples can be combined as appropriate.

(Embodiment 5)
In this embodiment, an electronic device that is one embodiment of the present invention will be described.

The electronic device of this embodiment includes the display device of one embodiment of the present invention in the display portion. The display device of one embodiment of the present invention has low power consumption and high reliability. Therefore, it can be used in display units of various electronic devices.

Examples of electronic devices include television devices, desktop or notebook personal computers, computer monitors, digital signage, large game machines such as pachinko machines, and other electronic devices with relatively large screens, as well as digital devices. Examples include cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, personal digital assistants, sound reproduction devices, and the like.

An example of a wearable device that can be worn on the head will be described with reference to FIGS. 16(A) to 16(D).

The electronic device 700A shown in FIG. 16(A) and the electronic device 700B shown in FIG. 16(B) each include a pair of display panels 751, a pair of housings 721, a communication unit (not shown), and a pair of , a control section (not shown), an imaging section (not shown), a pair of optical members 753, a frame 757, and a pair of nose pads 758.

A display device of one embodiment of the present invention can be applied to the display panel 751. Therefore, it is possible to provide a highly reliable electronic device.

The electronic device 700A and the electronic device 700B can each project an image displayed on the display panel 751 onto the display area 756 of the optical member 753. Since the optical member 753 has translucency, the user can see the image displayed in the display area superimposed on the transmitted image visually recognized through the optical member 753.

The electronic device 700A and the electronic device 700B may be provided with a camera capable of capturing an image of the front as an imaging unit. Furthermore, each of the electronic devices 700A and 700B is equipped with an acceleration sensor such as a gyro sensor to detect the direction of the user's head and display an image corresponding to the direction in the display area 756. You can also.

The communication unit has a wireless communication device, and can supply, for example, a video signal by the wireless communication device. Note that instead of or in addition to the wireless communication device, a connector to which a cable to which a video signal and a power supply potential are supplied may be connected may be provided.

Further, the electronic device 700A and the electronic device 700B are provided with batteries, and can be charged wirelessly and/or by wire.

The housing 721 may be provided with a touch sensor module.

Various touch sensors can be used as the touch sensor module. For example, various methods can be adopted, such as a capacitance method, a resistive film method, an infrared method, an electromagnetic induction method, a surface acoustic wave method, or an optical method. In particular, it is preferable to apply a capacitive type or optical type sensor to the touch sensor module.

The electronic device 800A shown in FIG. 16(C) and the electronic device 800B shown in FIG. 16(D) each include a pair of display sections 820, a housing 821, a communication section 822, and a pair of mounting sections 823. , a control section 824, a pair of imaging sections 825, and a pair of lenses 832.

A display device of one embodiment of the present invention can be applied to the display portion 820. Therefore, it is possible to provide a highly reliable electronic device.

The display unit 820 is provided inside the housing 821 at a position where it can be viewed through the lens 832. Furthermore, by displaying different images on the pair of display units 820, three-dimensional display using parallax can be performed.

The electronic device 800A and the electronic device 800B each have a mechanism that can adjust the left and right positions of the lens 832 and the display unit 820 so that they are in optimal positions according to the position of the user's eyes. It is preferable that you do so.

The mounting portion 823 allows the user to wear the electronic device 800A or the electronic device 800B on the head.

The imaging unit 825 has a function of acquiring external information. The data acquired by the imaging unit 825 can be output to the display unit 820. An image sensor can be used for the imaging unit 825. Further, a plurality of cameras may be provided so as to be able to handle a plurality of angles of view such as telephoto and wide angle.

The electronic device 800A may have a vibration mechanism that functions as a bone conduction earphone.

The electronic device 800A and the electronic device 800B may each have an input terminal. A cable for supplying a video signal from a video output device or the like and power for charging a battery provided in the electronic device can be connected to the input terminal.

An electronic device according to one embodiment of the present invention may have a function of wirelessly communicating with the earphone 750.

Furthermore, the electronic device may include an earphone section. Electronic device 700B shown in FIG. 16(B) includes earphone section 727. A portion of the wiring connecting the earphone section 727 and the control section may be arranged inside the housing 721 or the mounting section 723.

Similarly, electronic device 800B shown in FIG. 16(D) includes an earphone section 827. For example, the earphone section 827 and the control section 824 can be configured to be connected to each other by wire.

As described above, the electronic devices of one embodiment of the present invention include both glasses type (electronic device 700A and electronic device 700B, etc.) and goggle type (electronic device 800A and electronic device 800B, etc.). suitable.

Electronic device 6500 shown in FIG. 17(A) is a portable information terminal that can be used as a smartphone.

The electronic device 6500 includes a housing 6501, a display portion 6502, a power button 6503, a button 6504, a speaker 6505, a microphone 6506, a camera 6507, a light source 6508, and the like. The display section 6502 has a touch panel function.

A display device of one embodiment of the present invention can be applied to the display portion 6502. Therefore, it is possible to provide a highly reliable electronic device.

FIG. 17B is a schematic cross-sectional view including the end of the housing 6501 on the microphone 6506 side.

A light-transmitting protective member 6510 is provided on the display surface side of the housing 6501, and a display panel 6511, an optical member 6512, a touch sensor panel 6513, and a print are placed in a space surrounded by the housing 6501 and the protective member 6510. A board 6517, a battery 6518, and the like are arranged.

A display panel 6511, an optical member 6512, and a touch sensor panel 6513 are fixed to the protective member 6510 with an adhesive layer (not shown).

In a region outside the display portion 6502, a portion of the display panel 6511 is folded back, and an FPC 6515 is connected to the folded portion. An IC6516 is mounted on the FPC6515. The FPC 6515 is connected to a terminal provided on a printed circuit board 6517.

A display device of one embodiment of the present invention can be applied to the display panel 6511. Therefore, extremely lightweight electronic equipment can be realized. Furthermore, since the display panel 6511 is extremely thin, a large-capacity battery 6518 can be mounted while suppressing the thickness of the electronic device. Moreover, by folding back a part of the display panel 6511 and arranging the connection part with the FPC 6515 on the back side of the pixel part, an electronic device with a narrow frame can be realized.

FIG. 17(C) shows an example of a television device. A television device 7100 has a display section 7000 built into a housing 7171. Here, a configuration in which a casing 7171 is supported by a stand 7173 is shown.

A display device of one embodiment of the present invention can be applied to the display portion 7000. Therefore, it is possible to provide a highly reliable electronic device.

The television device 7100 shown in FIG. 17C can be operated using an operation switch included in a housing 7171 and a separate remote control operating device 7151.

FIG. 17(D) shows an example of a notebook personal computer. The notebook personal computer 7200 includes a housing 7211, a keyboard 7212, a pointing device 7213, an external connection port 7214, and the like. A display section 7000 is incorporated into the housing 7211.

A display device of one embodiment of the present invention can be applied to the display portion 7000. Therefore, it is possible to provide a highly reliable electronic device.

An example of digital signage is shown in FIG. 17(E) and FIG. 17(F).

A digital signage 7300 illustrated in FIG. 17E includes a housing 7301, a display portion 7000, a speaker 7303, and the like. Furthermore, it can have an LED lamp, an operation key (including a power switch or an operation switch), a connection terminal, various sensors, a microphone, and the like.

FIG. 17(F) shows a digital signage 7400 attached to a cylindrical pillar 7401. Digital signage 7400 has a display section 7000 provided along the curved surface of pillar 7401.

In FIGS. 17E and 17F, the display device of one embodiment of the present invention can be applied to the display portion 7000. Therefore, it is possible to provide a highly reliable electronic device.

The wider the display section 7000 is, the more information that can be provided at once can be increased. Furthermore, the wider the display section 7000 is, the easier it is to attract people's attention, and for example, the effectiveness of advertising can be increased.

Furthermore, as shown in FIGS. 17(E) and 17(F), the digital signage 7300 or the digital signage 7400 can cooperate with an information terminal 7311 or an information terminal 7411 such as a smartphone owned by the user through wireless communication. It is preferable that

The electronic device shown in FIGS. 18(A) to 18(G) includes a housing 9000, a display portion 9001, a speaker 9003, operation keys 9005 (including a power switch or an operation switch), a connection terminal 9006, and a sensor 9007 (power switch). , displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, tilt, vibration , odor or infrared rays), a microphone 9008, and the like.

The electronic devices shown in FIGS. 18(A) to 18(G) have various functions. For example, functions that display various information (still images, videos, text images, etc.) on the display unit, touch panel functions, functions that display calendars, dates or times, etc., functions that control processing using various software (programs), It can have a wireless communication function, a function of reading and processing programs or data recorded on a recording medium, and the like.

Details of the electronic device shown in FIGS. 18(A) to 18(G) will be described below.

FIG. 18(A) is a perspective view showing a portable information terminal 9171. The mobile information terminal 9171 can be used as a smartphone, for example. Note that the mobile information terminal 9171 may be provided with a speaker 9003, a connection terminal 9006, a sensor 9007, or the like. Furthermore, the mobile information terminal 9171 can display text and image information on multiple surfaces thereof. FIG. 18A shows an example in which three icons 9050 are displayed. Further, information 9051 indicated by a dashed rectangle can also be displayed on another surface of the display section 9001. Examples of the information 9051 include notification of incoming e-mail, SNS, telephone, etc., title of e-mail or SNS, sender's name, date and time, remaining battery level, radio field strength, and the like. Alternatively, an icon 9050 or the like may be displayed at the position where the information 9051 is displayed.

FIG. 18(B) is a perspective view showing the portable information terminal 9172. The mobile information terminal 9172 has a function of displaying information on three or more sides of the display section 9001. Here, an example is shown in which information 9052, information 9053, and information 9054 are displayed on different surfaces. For example, the user can check the information 9053 displayed at a position visible from above the mobile information terminal 9172 while storing the mobile information terminal 9172 in the chest pocket of clothes.

FIG. 18C is a perspective view of the tablet terminal 9173. The tablet terminal 9173 is capable of executing various applications such as mobile telephone, e-mail, text viewing and creation, music playback, Internet communication, and computer games, for example. The tablet terminal 9173 has a display section 9001, a camera 9002, a microphone 9008, and a speaker 9003 on the front of the housing 9000, an operation key 9005 as an operation button on the left side of the housing 9000, and a connection terminal on the bottom. 9006.

FIG. 18(D) is a perspective view showing a wristwatch-type portable information terminal 9200. The mobile information terminal 9200 can be used, for example, as a smart watch (registered trademark). Further, the display portion 9001 is provided with a curved display surface, and can perform display along the curved display surface. Further, the mobile information terminal 9200 can also make a hands-free call by mutually communicating with a headset capable of wireless communication, for example. Furthermore, the mobile information terminal 9200 can also perform data transmission and charging with other information terminals through the connection terminal 9006. Note that the charging operation may be performed by wireless power supply.

18(E) to FIG. 18(G) are perspective views showing a foldable portable information terminal 9201. Also, FIG. 18(E) shows the expanded state of the mobile information terminal 9201, FIG. 18(G) shows the folded state, and FIG. 18(F) shows the change from one of FIG. 18(E) and FIG. 18(G) to the other. It is a perspective view of a state in the middle of doing. The portable information terminal 9201 has excellent portability in the folded state, and has excellent display visibility due to its wide seamless display area in the unfolded state. A display portion 9001 included in a mobile information terminal 9201 is supported by three casings 9000 connected by hinges 9055. For example, the display portion 9001 can be bent with a radius of curvature of 0.1 mm or more and 150 mm or less.

This embodiment mode can be combined with other embodiment modes or examples as appropriate. Further, in this specification, when a plurality of configuration examples are shown in one embodiment, the configuration examples can be combined as appropriate.

This example describes the detailed manufacturing method of light-emitting device 1, which is a light-emitting device of one embodiment of the present invention, and comparative light-emitting device 1, which is a comparative light-emitting device, and the results of measuring their initial characteristics and reliability. show.

The structural formulas of the main compounds used in this example are shown below.

(Method for manufacturing light emitting device 1)
First, 50 nm of titanium (Ti), 70 nm of aluminum (Al), and 6 nm of Ti were stacked on a glass substrate from the substrate side, and then baked at 300° C. for 1 hour in the air. Thereafter, a 10 nm film of indium tin oxide containing silicon oxide (ITSO) was formed by sputtering to form a first electrode 101 with a size of 2 mm x 2 mm. Note that ITSO functions as an anode and is regarded as the first electrode 101 together with the laminated structure of Ti and Al described above.

Next, as a pretreatment for forming a light emitting device on the substrate, the surface of the substrate was washed with water.

Thereafter, the substrate was introduced into a vacuum evaporation apparatus whose internal pressure was reduced to approximately 1×10 ^-4 Pa, and vacuum baking was performed at 170°C for 60 minutes in the heating chamber of the vacuum evaporation apparatus. Cooled separately.

Next, the substrate is fixed to a holder provided in a vacuum evaporation apparatus so that the surface on which the first electrode 101 is formed faces downward, and a vapor deposition method is applied to the inorganic insulating film and the first electrode 101. N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene represented by the above structural formula (i) -2-Amine (abbreviation: PCBBiF) and an electron acceptor material (OCHD-003) containing fluorine with a molecular weight of 672 were co-evaporated to a thickness of 10 nm at a weight ratio of 1:0.03 (=PCBBiF:OCHD-003). Then, a hole injection layer 111 was formed.

On the hole injection layer 111, PCBBiF was deposited to a thickness of 10 nm to form a hole transport layer 112.

Subsequently, 8-(1,1':4',1''-terphenyl-3-yl)-4-[3-(dibenzo Thiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm) and 9-(2-naphthyl)-9' represented by the above structural formula (iii) -phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: βNCCP) and [2-d3-methyl-8-(2-pyridinyl-κN)benzofuro] represented by the above structural formula (iv). [2,3-b]pyridine-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN2)phenyl-κC]iridium(III) (abbreviation: Ir(5mppy-d3) ₂ (mbfpypy-d3 )) at a weight ratio of 0.6:0.4:0.1 (=8mpTP-4mDBtPBfpm:βNCCP:Ir(5mppy-d3) ₂ (mbfpypy-d3)) to emit light. Layer 113 was formed.

Thereafter, 2-{3-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}dibenzo[f,h ] Quinoxaline (abbreviation: 2mPCCzPDBq) is evaporated to a thickness of 10 nm to form a first electron transport layer, and 2,2′-(1,3-phenylene)bis( A second electron transport layer was formed by depositing 9-phenyl-1,10-phenanthroline (abbreviation: mPPhen2P) to a thickness of 15 nm, thereby forming the electron transport layer 114. Note that the first electron transport layer also functions as a hole blocking layer.

Subsequently, an electron injection layer 115 is formed by co-evaporating 1.5 nm of lithium fluoride (LiF) and ytterbium (Yb) at a volume ratio of 1:0.5 (=LiF:Yb), and then, The second electrode 102 was formed by co-evaporating silver (Ag) and magnesium (Mg) at a volume ratio of 1:0.1 and a film thickness of 25 nm, and a light-emitting device of one embodiment of the present invention was manufactured. . Furthermore, ITO is formed as a cap layer to a thickness of 70 nm on the second electrode 102 to improve light extraction efficiency.

Next, in a glove box with a nitrogen atmosphere, the light-emitting device is sealed with a glass substrate so that it is not exposed to the atmosphere (a UV-curable sealant is applied around the element, and the light-emitting device is sealed so that it is not irradiated). A light emitting device 1 was formed by irradiating only the material with UV and heat treatment at 80° C. for 1 hour under atmospheric pressure.

(Method for manufacturing comparative light emitting device 1)
Comparative light-emitting device 1 was formed in the same manner as light-emitting device 1 from the first electrode to the hole transport layer, and then, on the hole transport layer, 8-(biphenyl- 4-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8BP-4mDBtPBfpm) and the compound represented by the above structural formula (viii). 9,9'-diphenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCP) and [2-d3-methyl-(2-pyridinyl) represented by the above structural formula (ix) -κN) benzofuro[2,3-b]pyridine-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: Ir(ppy) ₂ (mbfpypy-d3)) The light-emitting layer 113 was formed by co-evaporating 40 nm at a weight ratio of 0.6:0.4:0.1 (=8BP-4mDBtPBfpm:PCCP:Ir(ppy) ₂ (mbfpypy-d3)).

Thereafter, 2-[3-(3'-dibenzothiophen-4-yl)biphenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II) represented by the above structural formula (x) was added to a thickness of 20 nm. 2,9-di(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: :NBPhen) to a thickness of 15 nm to form a second electron transport layer, thereby forming the electron transport layer 114. Note that the first electron transport layer also functions as a hole blocking layer.

Subsequently, lithium fluoride (LiF) is deposited to a thickness of 1 nm to form an electron injection layer 115, and then silver (Ag) and magnesium (Mg) are deposited at a volume ratio of 1:0.1 and a film thickness of 25 nm. The second electrode 102 was formed by codeposition, and a light-emitting device of one embodiment of the present invention was manufactured. Furthermore, ITO is formed as a cap layer to a thickness of 70 nm on the second electrode 102 to improve light extraction efficiency.

Next, in a glove box with a nitrogen atmosphere, the light-emitting device is sealed with a glass substrate so that it is not exposed to the atmosphere (a UV-curable sealant is applied around the element, and the light-emitting device is sealed so that it is not irradiated). Comparative light emitting device 1 was formed by irradiating only the material with UV and heat treatment at 80° C. for 1 hour under atmospheric pressure.

The device structures of Light Emitting Device 1 and Comparative Light Emitting Device 1 are shown below.

The luminance-current density characteristics of Light-emitting Device 1 and Comparative Light-emitting Device 1 are shown in Figure 19, the current efficiency-luminance characteristics are shown in Figure 20, the brightness-voltage characteristics are shown in Figure 21, the current density-voltage characteristics are shown in Figure 22, and the emission spectra are shown. It is shown in FIG. Further, the values of voltage, current, current density, CIE chromaticity, and current efficiency near 1000 cd/cm ² are shown below. Note that the brightness, CIE chromaticity, and emission spectrum were measured using a spectroradiometer (SR-UL1R, manufactured by Topcon Corporation) at room temperature.

It can be seen from FIGS. 19 to 23 that the light emitting device 1 is a light emitting device with better efficiency and driving voltage than the comparative light emitting device 1.

Subsequently, FIG. 24 shows the results of measuring changes in brightness with respect to driving time during constant current driving at a current density of 50 mA/cm ² . From FIG. 24, it was found that the light emitting device 1 was a light emitting device with a good lifespan, having a lifespan approximately twice as long as that of the comparative light emitting device 1.

Here, the light emitting device 1 has, in the light emitting layer, 8mpTP-4mDBtPBfpm as the first organic compound, βNCCP as the second organic compound, and Ir(5mppy-d3) ₂ (mbfpypy-d3) as the phosphorescent substance, according to the present invention. This is a light-emitting device according to one embodiment.

That is, the first organic compound 8mpTP-4mDBtPBfpm has a benzofuropyrimidine skeleton which is a heteroaromatic ring skeleton, a terphenyl group which is an aromatic hydrocarbon group, and the lowest triplet excited level is terphenyl. It is an organic compound derived from phenyl group. Further, βNCCP, which is the second organic compound, has a bicarbazole skeleton and has a lowest triplet excitation energy of 2.55 eV (2.20 eV or more and 2.65 eV or less). Further, Ir(5mppy-d3) ₂ (mbfpypy-d3) is a phosphorescent substance that exhibits green phosphorescence.

The lowest triplet excitation energy level (T ₁ level) of βNCCP was calculated by measuring the emission spectrum (phosphorescence spectrum) at a measurement temperature of 10 K using a thin film of βNCCP formed to a thickness of 50 nm on a quartz substrate. The measurement was performed using a microscope PL device LabRAM HR-PL (manufactured by Horiba, Ltd.) and a He-Cd laser (325 nm) as excitation light. As a result, the peak on the shortest wavelength side of the emission spectrum (phosphorescence spectrum) of βNCCP was 491 nm (2.53 eV), and the emission end on the shortest wavelength side was 486 nm (2.55 eV). Note that the emission end is defined by drawing a tangent at the value where the slope of the shortest wavelength side of the peak (or shoulder peak) observed at the shortest wavelength of the emission spectrum (phosphorescence spectrum) is maximum, and then drawing a tangent between that tangent and the horizontal axis (wavelength). Alternatively, it was calculated from the intersection with the baseline.

Similarly, when the lowest triplet excitation energy level of PCCP was measured, the emission end on the shortest wavelength side of the emission spectrum of PCCP was 454 nm (2.73 eV).

Note that the first organic compound and the second organic compound in the light emitting device 1 form an exciplex capable of exciting the green phosphorescent substance. Moreover, since the second organic compound has a relatively low _T1 level of 2.55 eV, excitons in an excessively high energy state are not generated. Also, in the first organic compound, the lowest triplet excited level is present in the terphenyl group (especially preferably a terphenyl group substituted at the meta position), so that the T ₁ level is the same as in the second organic compound. The value is moderate, not too high. From this, the light emitting device 1 was able to be a highly reliable light emitting device.

On the other hand, in comparative light emitting device 1, 8BP-4mDBtPBfpm, which corresponds to the first substance, has a benzofuropyrimidine skeleton that is a heteroaromatic ring skeleton and a biphenyl group that is an aromatic hydrocarbon group; It is an organic compound whose lowest triplet excited level is not derived from a biphenyl group but from a dibenzothiophenyl group. Therefore, the T ₁ level of 8BP-4mDBtPBfpm is higher than that of 8mpTP-4mDBtPBfpm, and high-energy excitons are generated. PCCP, which corresponds to the second organic compound, has a bicarbazole skeleton and is an organic compound with a lowest triplet excitation energy of 2.73 eV (2.65 eV or more). Furthermore, Ir(ppy) ₂ (mbfpypy-d3) is a phosphorescent substance that exhibits green phosphorescence.

When the lowest triplet excitation energy level (T ₁ level) of 8mpTP-4mDBtPBfpm and 8BP-4mDBtPBfpm was measured using the same method as βNCCP, the peak on the shortest wavelength side of the emission spectrum of 8mpTP-4mDBtPBfpm was as follows. 500 nm (2.48 eV), and the emission end on the shortest wavelength side was 486 nm (2.55 eV). Furthermore, the peak on the shortest wavelength side of the emission spectrum of 8BP-4mDBtPBfpm was 495 nm (2.51 eV), and the emission end on the shortest wavelength side was 482 nm (2.57 eV). Therefore, it can be said that 8mpTP-4mDBtPBfpm is an organic compound having a lower lowest triplet excitation energy level than 8BP-4mDBtPBfpm.

In this example, the results of computational analysis of the first organic compound that can be used in the light-emitting device of one embodiment of the present invention will be described with reference to FIGS. 25 to 27.

Regarding the organic compounds represented by 8mpTP-4mDBtPBfpm (structural formula (200)) and structural formula (216), which are specific examples of the first organic compound, and 8BP-4mDBtPBfpm, which is a comparative example, the distribution of HOMO, LUMO We analyzed the distribution of and the localization of the lowest triplet excited state.

<Calculation method>
The distribution of HOMO and LUMO was analyzed by vibrational (spin density) analysis in the most stable structure in which the S _{0 level is the lowest with respect to the singlet ground state (S 0 )} of the compound. The localization of the lowest triplet excited state was analyzed by spin density analysis in the most stable structure in which the T ₁ level is the lowest with respect to the lowest triplet excited state (T ₁ ) of the compound. The calculation method used Density Functional Theory (DFT). The total energy calculated by DFT is expressed as the sum of exchange-correlation energy including potential energy, electrostatic energy between electrons, kinetic energy of electrons, and complex interactions between electrons. In DFT, the exchange-correlation interaction is approximated by a functional (meaning a function of functions) of one-electron potential expressed by electron density, so calculation is fast. Here, the weight of each parameter related to exchange and correlation energy was defined using B3LYP, which is a mixed functional. Furthermore, 6-311G(d,p) was used as the basis function. Gaussian 09 was used as the calculation program.

The analysis results of 8mpTP-4mDBtPBfpm are shown in FIG. 25, the analysis results of the organic compound represented by structural formula (216) are shown in FIG. 26, and the analysis results of 8BP-4mDBtPBfpm are shown in FIG. 27. In FIGS. 25 to 27, the spheres in the figures represent atoms constituting the compound, and the clouds around the atoms represent the spin density distribution when the same density value is 0.003. It is something. In FIG. 25(A), FIG. 26(A), and FIG. 27(A), clouds arranged around atoms indicate the distribution of LUMO in the molecule. In FIGS. 25(B), 26(B), and 27(B), clouds placed around atoms indicate the HOMO distribution in the molecule. In FIG. 25(C), FIG. 26(C), and FIG. 27(C), clouds arranged around atoms indicate the localized state of the lowest triplet excited state in the molecule.

25 and 26, in 8mpTP-4mDBtPBfpm and the organic compound represented by the structural formula (216), the lowest triplet excited state is localized to the terphenyl group corresponding to the first substituent of the first organic compound. There is. Therefore, in 8mpTP-4mDBtPBfpm and the organic compound represented by the structural formula (216), the lowest triplet excited state is localized in the 1,1':4',1''-terphenyl skeleton of the first substituent. However, it was found that the T ₁ level of 8mpTP-4mDBtPBfpm and the organic compound represented by the structural formula (216) originates from the 1,1':4',1''-terphenyl skeleton.

On the other hand, from FIG. 27, the lowest triplet excited state of 8BP-4mDBtPBfpm is due to not only the 1,1'-biphenyl-4-yl group corresponding to the first substituent of the first organic compound but also the electron transporting property. It is also distributed in the [1]benzofuro[3,2-d]pyrimidine ring corresponding to the skeleton. Therefore, it was found that in 8BP-4mDBtPBfpm, the lowest triplet excited state was not localized in the first substituent.

This example describes the detailed manufacturing method of light-emitting device 2, which is a light-emitting device of one embodiment of the present invention, and comparative light-emitting device 2, which is a comparative light-emitting device, and the results of measuring their initial characteristics and reliability. show.

The structural formulas of the main compounds used in this example are shown below.

(Method for manufacturing light emitting device 2)
First, on a glass substrate, from the substrate side, 100 nm of silver (Ag) and 10 nm of indium tin oxide containing silicon oxide (ITSO) were sequentially laminated by sputtering method to form a first electrode 101 with a size of 2 mm x 2 mm. was formed. Note that ITSO functions as an anode and is regarded as the first electrode 101 together with the above Ag.

Next, as a pretreatment for forming a light emitting device on the substrate, the surface of the substrate was washed with water.

Thereafter, the substrate was introduced into a vacuum evaporation apparatus whose internal pressure was reduced to approximately 1×10 ^-4 Pa, and vacuum baking was performed at 170°C for 60 minutes in the heating chamber of the vacuum evaporation apparatus. Cooled separately.

Next, the substrate is fixed to a holder provided in a vacuum evaporation apparatus so that the surface on which the first electrode 101 is formed faces downward, and the inorganic insulating film and the first electrode 101 are coated on the inorganic insulating film and the first electrode 101 by a vapor deposition method. N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene represented by the above structural formula (i) -2-Amine (abbreviation: PCBBiF) and an electron acceptor material containing fluorine (OCHD-003) with a molecular weight of 672 were co-evaporated to a thickness of 10 nm at a weight ratio of 1:0.03 (=PCBBiF:OCHD-003). Thus, a hole injection layer 111 was formed.

On the hole injection layer 111, PCBBiF was deposited to a thickness of 15 nm to form a hole transport layer 112.

Subsequently, 8-(1,1':4',1''-terphenyl-3-yl)-4-[3-(dibenzo Thiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm) and 9-(2-naphthyl)-9' represented by the above structural formula (iii) -phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: βNCCP) and [2-d3-methyl-8-(2-pyridinyl-κN)benzofuro] represented by the above structural formula (iv). [2,3-b]pyridine-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN2)phenyl-κC]iridium(III) (abbreviation: Ir(5mppy-d ₃ ) ₂ (mbfpypy- d ₃ )) in a weight ratio of 0.5:0.5:0.1 (=8mpTP-4mDBtPBfpm:βNCCP:Ir(5mppy-d ₃ ) ₂ (mbfpypy-d ₃ )). A light emitting layer 113 was formed by vapor deposition.

Thereafter, 2-{3-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}dibenzo[f,h ] Quinoxaline (abbreviation: 2mPCCzPDBq) is evaporated to a thickness of 10 nm to form a first electron transport layer, and 2,2′-(1,3-phenylene)bis( A second electron transport layer was formed by depositing 9-phenyl-1,10-phenanthroline (abbreviation: mPPhen2P) to a thickness of 20 nm, thereby forming the electron transport layer 114. Note that the first electron transport layer also functions as a hole blocking layer.

Subsequently, an electron injection layer 115 is formed by co-evaporating 1.5 nm of lithium fluoride (LiF) and ytterbium (Yb) at a volume ratio of 1:0.5 (=LiF:Yb), and then, The second electrode 102 was formed by co-evaporating silver (Ag) and magnesium (Mg) at a volume ratio of 1:0.1 and a film thickness of 15 nm, and a light-emitting device of one embodiment of the present invention was manufactured. . Further, on the second electrode 102, 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P- II) was formed as a cap layer to a thickness of 70 nm to improve light extraction efficiency.

Next, in a glove box with a nitrogen atmosphere, the light-emitting device is sealed with a glass substrate so that it is not exposed to the atmosphere (a UV-curable sealant is applied around the element, and the light-emitting device is sealed so that it is not irradiated). A light emitting device 2 was formed by irradiating only the material with UV and heat treatment at 80° C. for 1 hour under atmospheric pressure.

(Method for manufacturing comparative light emitting device 2)
Comparative light emitting device 2 replaces 8mpTP-4mDBtPBfpm in light emitting device 2 with 8-(biphenyl-4-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]- represented by the above structural formula (vii). [1] It was produced in the same manner as Light-emitting device 2 except that benzofuro[3,2-d]pyrimidine (abbreviation: 8BP-4mDBtPBfpm) was used.

The device structures of light emitting device 2 and comparative light emitting device 2 are shown below.

The brightness-current density characteristics of Light-emitting Device 2 and Comparative Light-emitting Device 2 are shown in FIG. 28, the current efficiency-brightness characteristics are shown in FIG. 29, the brightness-voltage characteristics are shown in FIG. 30, the current density-voltage characteristics are shown in FIG. 31, and the emission spectra are shown. It is shown in FIG. Further, the values of voltage, current, current density, CIE chromaticity, and current efficiency near 1000 cd/cm ² are shown below. Note that the brightness, CIE chromaticity, and emission spectrum were measured using a spectroradiometer (SR-UL1R, manufactured by Topcon Corporation) at room temperature.

It can be seen from FIGS. 28 to 32 that both the light emitting device 2 and the comparative light emitting device 2 are light emitting devices having good characteristics.

Next, FIG. 33 shows the results of measuring changes in brightness with respect to driving time during constant current driving at a current density of 50 mA/cm ² for Light Emitting Device 2 and Comparative Light Emitting Device 2. From FIG. 33, the time for luminance to deteriorate by 10% (LT90) is 263 hours for light-emitting device 2 and 232 hours for comparative light-emitting device 2, and light-emitting device 2 has a longer life than comparative light-emitting device 2. I found out something.

Here, the light emitting device 2 has, in the light emitting layer, 8mpTP-4mDBtPBfpm as the first organic compound, βNCCP as the second organic compound, and Ir(5mppy-d ₃ ) ₂ (mbfpypy-d ₃ ) as the phosphorescent substance. This is a light-emitting device according to one embodiment of the present invention.

That is, the first organic compound 8mpTP-4mDBtPBfpm has a benzofuropyrimidine skeleton which is a heteroaromatic ring skeleton, a terphenyl group which is an aromatic hydrocarbon group, and the lowest triplet excited level is terphenyl. It is an organic compound derived from phenyl group. Further, βNCCP, which is the second organic compound, has a bicarbazole skeleton and has a lowest triplet excitation energy of 2.55 eV (2.20 eV or more and 2.65 eV or less). Further, Ir(5mppy-d ₃ ) ₂ (mbfpypy-d ₃ ) is a phosphorescent substance that exhibits green phosphorescence.

The lowest triplet excitation energy level (T ₁ level) of βNCCP was calculated by measuring the emission spectrum (phosphorescence spectrum) at a measurement temperature of 10 K using a thin film of βNCCP formed to a thickness of 50 nm on a quartz substrate. The measurement was performed using a microscope PL device LabRAM HR-PL (manufactured by Horiba, Ltd.) and a He-Cd laser (325 nm) as excitation light. As a result, the peak on the shortest wavelength side of the emission spectrum (phosphorescence spectrum) of βNCCP was 491 nm (2.53 eV), and the emission end on the shortest wavelength side was 486 nm (2.55 eV). Note that the emission end is defined by drawing a tangent at the value where the slope of the shortest wavelength side of the peak (or shoulder peak) observed at the shortest wavelength of the emission spectrum (phosphorescence spectrum) is maximum, and then drawing a tangent between that tangent and the horizontal axis (wavelength). Alternatively, it was calculated from the intersection with the baseline.

Note that the first organic compound and the second organic compound in the light emitting device 2 form an exciplex capable of exciting the green phosphorescent substance. Moreover, since the second organic compound has a relatively low _T1 level of 2.55 eV, excitons in an excessively high energy state are not generated. Also, in the first organic compound, the lowest triplet excited level is present in the terphenyl group (especially preferably a terphenyl group substituted at the meta position), so that the T ₁ level is the same as in the second organic compound. The value is moderate, not too high. From this, the light emitting device 2 was able to be a highly reliable light emitting device.

On the other hand, in comparative light emitting device 2, 8BP-4mDBtPBfpm, which corresponds to the first substance, has a benzofuropyrimidine skeleton that is a heteroaromatic ring skeleton and a biphenyl group that is an aromatic hydrocarbon group. It is an organic compound whose lowest triplet excited level is not derived from a biphenyl group but from a dibenzothiophenyl group. Therefore, the T ₁ level of 8BP-4mDBtPBfpm is higher than that of 8mpTP-4mDBtPBfpm, and high-energy excitons are generated.

When the lowest triplet excitation energy level (T ₁ level) of 8mpTP-4mDBtPBfpm and 8BP-4mDBtPBfpm was measured using the same method as βNCCP, the peak on the shortest wavelength side of the emission spectrum of 8mpTP-4mDBtPBfpm was as follows. 500 nm (2.48 eV), and the emission end on the shortest wavelength side was 486 nm (2.55 eV). Furthermore, the peak on the shortest wavelength side of the emission spectrum of 8BP-4mDBtPBfpm was 495 nm (2.51 eV), and the emission end on the shortest wavelength side was 482 nm (2.57 eV). Therefore, it can be said that 8mpTP-4mDBtPBfpm is a substance having a lower lowest triplet excitation energy level than 8BP-4mDBtPBfpm.

In this example, detailed methods for manufacturing light-emitting device 3 and light-emitting device 4, which are light-emitting devices of one embodiment of the present invention, and the results of measuring their initial characteristics and reliability are shown.

The structural formulas of the main compounds used in this example are shown below.

(Method for manufacturing light emitting device 3)
First, on a glass substrate, from the substrate side, 100 nm of silver (Ag) and 10 nm of indium tin oxide containing silicon oxide (ITSO) were sequentially laminated by sputtering method to form a first electrode 101 with a size of 2 mm x 2 mm. was formed. Note that ITSO functions as an anode and is regarded as the first electrode 101 together with the above Ag.

Next, as a pretreatment for forming a light emitting device on the substrate, the surface of the substrate was washed with water.

Thereafter, the substrate was introduced into a vacuum evaporation apparatus whose internal pressure was reduced to approximately 1×10 ^-4 Pa, and vacuum baking was performed at 170°C for 60 minutes in the heating chamber of the vacuum evaporation apparatus. Cooled separately.

Next, the substrate is fixed to a holder provided in a vacuum evaporation apparatus so that the surface on which the first electrode 101 is formed faces downward, and a vapor deposition method is applied to the inorganic insulating film and the first electrode 101. N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene represented by the above structural formula (i) -2-Amine (abbreviation: PCBBiF) and an electron acceptor material (OCHD-003) containing fluorine with a molecular weight of 672 were co-evaporated to a thickness of 10 nm at a weight ratio of 1:0.03 (=PCBBiF:OCHD-003). Then, a hole injection layer 111 was formed.

On the hole injection layer 111, PCBBiF was deposited to a thickness of 10 nm to form a hole transport layer 112.

Subsequently, 8-(1,1':4',1''-terphenyl-3-yl)-4-[3-(dibenzo Thiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm) and 9-(2-naphthyl)-9' represented by the above structural formula (iii) -phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: βNCCP) and [2-d3-methyl-8-(2-pyridinyl-κN)benzofuro] represented by the above structural formula (iv). [2,3-b]pyridine-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN2)phenyl-κC]iridium(III) (abbreviation: Ir(5mppy-d ₃ ) ₂ (mbfpypy- d ₃ )) in a weight ratio of 0.5:0.5:0.1 (=8mpTP-4mDBtPBfpm:βNCCP:Ir(5mppy-d ₃ ) ₂ (mbfpypy-d ₃ )). A light emitting layer 113 was formed by vapor deposition.

Thereafter, 2-{3-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}dibenzo[f,h ] Quinoxaline (abbreviation: 2mPCCzPDBq) is evaporated to a thickness of 10 nm to form a first electron transport layer, and 2,2′-(1,3-phenylene)bis( A second electron transport layer was formed by depositing 9-phenyl-1,10-phenanthroline (abbreviation: mPPhen2P) to a thickness of 10 nm, thereby forming the electron transport layer 114. Note that the first electron transport layer also functions as a hole blocking layer.

Subsequently, an electron injection layer 115 is formed by co-evaporating 1.5 nm of lithium fluoride (LiF) and ytterbium (Yb) at a volume ratio of 1:0.5 (=LiF:Yb), and then, The second electrode 102 was formed by co-evaporating silver (Ag) and magnesium (Mg) at a volume ratio of 1:0.1 and a film thickness of 25 nm, and a light-emitting device of one embodiment of the present invention was manufactured. . Further, on the second electrode 102, 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P- II) was formed as a cap layer to a thickness of 70 nm to improve light extraction efficiency.

Next, in a glove box with a nitrogen atmosphere, the light-emitting device is sealed with a glass substrate so that it is not exposed to the atmosphere (a UV-curable sealant is applied around the element, and the light-emitting device is sealed so that it is not irradiated). A light emitting device 3 was formed by irradiating only the material with UV and heat treatment at 80° C. for 1 hour under atmospheric pressure.

(Method for manufacturing light emitting device 4)
Light-emitting device 4 replaces 8mpTP-4mDBtPBfpm in light-emitting device 3 with 8-(1,1′:4′,1″-terphenyl-3-yl-2,4,5) represented by the above structural formula (xiii). ,6,2′,3′,5′,6′,2′′,3′′,4′′,5′′,6′′-d ₁₃ )-4-[3-(dibenzothiophene-4- yl-1,2,3,6,7,8,9-d ₇ ) phenyl-2,4,6-d ₃ ]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm- It was produced in the same manner as Light-emitting device 3 except that it was changed to d ₂₃ ).

Device structures of light emitting device 3 and light emitting device 4 are shown below.

The luminance-current density characteristics of the light-emitting device 3 and the light-emitting device 4 are shown in FIG. 34, the current efficiency-brightness characteristics are shown in FIG. 35, the brightness-voltage characteristics are shown in FIG. 36, the current density-voltage characteristics are shown in FIG. 37, and the emission spectra are shown in FIG. 38. Further, the values of voltage, current, current density, CIE chromaticity, and current efficiency near 2000 cd/m ² are shown below. Note that the brightness, CIE chromaticity, and emission spectrum were measured using a spectroradiometer (SR-UL1R, manufactured by Topcon Corporation) at room temperature.

It can be seen from FIGS. 34 to 38 that both light-emitting device 3 and light-emitting device 4 have good characteristics.

Subsequently, FIG. 39 shows the results of measuring changes in brightness with respect to drive time during constant current driving of light emitting device 3 and light emitting device 4 at a current density of 50 mA/cm ² . From FIG. 39, the brightness after 250 hours is 90% of the initial brightness for light-emitting device 3 and 92% for light-emitting device 4, and both light-emitting device 3 and light-emitting device 4 are light-emitting devices with good reliability. In particular, it was found that the light emitting device 4 has a longer life.

Here, the light emitting device 3 has, in the light emitting layer, 8mpTP-4mDBtPBfpm as the first organic compound, βNCCP as the second organic compound, and Ir(5mppy-d ₃ ) ₂ (mbfpypy-d ₃ ) as the phosphorescent substance. This is a light-emitting device according to one embodiment of the present invention. Further, the light emitting device 4 includes, in the light emitting layer, 8mpTP-4mDBtPBfpm-d ₂₃ as the first organic compound, βNCCP as the second organic compound, and Ir(5mppy-d ₃ ) ₂ (mbfpypy-d ₃ ) as the phosphorescent material. A light-emitting device of one embodiment of the present invention has the following.

That is, the first organic compound 8mpTP-4mDBtPBfpm or 8mpTP-4mDBtPBfpm-d ₂₃ has a benzofuropyrimidine skeleton that is a heteroaromatic ring skeleton, has a terphenyl group that is an aromatic hydrocarbon group, and has a minimum It is an organic compound whose triplet excited level is derived from a terphenyl group. Further, βNCCP, which is the second organic compound, has a bicarbazole skeleton and has a lowest triplet excitation energy of 2.55 eV (2.20 eV or more and 2.65 eV or less). Further, Ir(5mppy-d ₃ ) ₂ (mbfpypy-d ₃ ) is a phosphorescent substance that exhibits green phosphorescence.

The lowest triplet excitation energy level (T ₁ level) of βNCCP was calculated by measuring the emission spectrum (phosphorescence spectrum) at a measurement temperature of 10 K using a thin film of βNCCP formed to a thickness of 50 nm on a quartz substrate. The measurement was performed using a microscope PL device LabRAM HR-PL (manufactured by Horiba, Ltd.) and a He-Cd laser (325 nm) as excitation light. As a result, the peak on the shortest wavelength side of the emission spectrum (phosphorescence spectrum) of βNCCP was 491 nm (2.53 eV), and the emission end on the shortest wavelength side was 486 nm (2.55 eV). Note that the emission end is defined by drawing a tangent at the value where the slope of the shortest wavelength side of the peak (or shoulder peak) observed at the shortest wavelength of the emission spectrum (phosphorescence spectrum) is maximum, and then drawing a tangent between that tangent and the horizontal axis (wavelength). Alternatively, it was calculated from the intersection with the baseline.

Note that the first organic compound and the second organic compound in the light emitting device 3 and the light emitting device 4 form an exciplex capable of exciting the green phosphorescent substance. Moreover, since the second organic compound has a relatively low _T1 level of 2.55 eV, excitons in an excessively high energy state are not generated. Also, in the first organic compound, the lowest triplet excited level is present in the terphenyl group (especially preferably a terphenyl group substituted at the meta position), so that the T ₁ level is the same as in the second organic compound. The value is moderate, not too high. From this, light emitting device 3 and light emitting device 4 were able to be light emitting devices with good reliability.

When the lowest triplet excitation energy level (T ₁ level) of 8mpTP-4mDBtPBfpm and 8mpTP-4mDBtPBfpm-d ₂₃ was measured using the same method as βNCCP, it was found that The peak was 500 nm (2.48 eV), and the emission end on the shortest wavelength side was 486 nm (2.55 eV). Furthermore, the peak on the shortest wavelength side of the emission spectrum of 8mpTP-4mDBtPBfpm-d ₂₃ was 501 nm (2.48 eV), and the emission end on the shortest wavelength side was 484 nm (2.56 eV).

Next, the results of measuring the emission spectra and emission quantum yields of 2Me-THF solutions of 8mpTP-4mDBtPBfpm and 8mpTP-4mDBtPBfpm-d ₂₃ after cooling with liquid nitrogen are shown.

The emission spectrum and emission quantum yield were measured using an absolute PL quantum yield measurement device (C11347-01 manufactured by Hamamatsu Photonics Co., Ltd.) in a glove box (LABstar M13 (1250/780) manufactured by Bright Co., Ltd.). Under a nitrogen atmosphere, 2Me-THF deoxidizing solutions (0.120 mmol/L) of 8mpTP-4mDBtPBfpm and 8mpTP-4mDBtPBfpm-d ₂₃ were placed in a quartz cell, the cells were sealed tightly, and the cells were cooled with liquid nitrogen to perform measurements.8mpTP The measurement results of the emission spectra of -4mDBtPBfpm and 8mpTP-4mDBtPBfpm-d ₂₃ are shown in Figure 40. The horizontal axis represents the wavelength, and the vertical axis represents the emission intensity.

As shown in FIG. 40, an emission spectrum in which fluorescence and phosphorescence were mixed was observed in all samples. The spectrum in the vicinity of 351 nm to 455 nm was confirmed to be fluorescence based on room temperature measurements and emission lifetime measurements. Furthermore, since the spectrum in the vicinity of 455 nm to 660 nm was observed only in low-temperature measurements, it was confirmed that it was derived from phosphorescence.

In addition, from the measurement results of the luminescence quantum yield, the quantum yield (Φ _f (H)) of the fluorescent component (351 nm to 455 nm) at low temperature (temperature cooled with liquid nitrogen) at 8mpTP-4mDBtPBfpm is 8.5%. It turned out to be. Further, the quantum yield (Φ _p (H)) of the phosphorescent component (455 nm to 660 nm) was found to be 10%.

In addition, from the measurement results of the luminescence quantum yield, the quantum yield (Φ _f (D)) of the fluorescent component (351 nm to 455 nm) at _low temperature (temperature cooled with liquid nitrogen) in 8mpTP-4mDBtPBfpm-d 23 is 8. It was found to be .5%. Further, the quantum yield (Φ _p (D)) of the phosphorescent component (455 nm to 660 nm) was found to be 15%.

That is, at low temperature (temperature cooled with liquid nitrogen), the quantum yield of the phosphorescent component of 8mpTP-4mDBtPBfpm-d ₂₃ is 1.5 times as large as the quantum yield of the phosphorescent component of 8mpTP-4mDBtPBfpm, and the fluorescence It was found that the quantum yields of the components were almost the same.

Also shown are the results of measuring the luminescence lifetimes of 2-methyltetrahydrofuran (2Me-THF) solutions of 8mpTP-4mDBtPBfpm and 8mpTP-4mDBtPBfpm-d ₂₃ by cooling them with liquid nitrogen.

A fluorometer (FP-8600, manufactured by JASCO Corporation) was used to measure the luminescence lifetime. 2Me-THF solutions (0.120 mmol/L) of each of 8mpTP-4mDBtPBfpm and 8mpTP-4mDBtPBfpm-d ₂₃ were placed in a quartz cell under the atmosphere, and the cells were cooled with liquid nitrogen and measured. In this measurement, the wavelength of the excitation light is 320 nm, and the wavelength of the light to be measured is 515 nm.The quartz cell containing the solution is irradiated with the excitation light for about 30 seconds, and the excitation light is blocked by a shutter and then attenuated. Time-resolved measurements were performed by measuring the intensity of light emission at 10 ms intervals. Note that the bandwidth of the excitation light and measurement light was 10 nm. The obtained time decay curve is shown in FIG. The horizontal axis represents time, and the vertical axis represents luminescence intensity.

As shown in FIG. 41, it was found that the emission intensity attenuated monoexponentially. The luminescence lifetime was calculated from the obtained decay curve. The luminescence lifetime of 8mpTP-4mDBtPBfpm was 2.8 s. The luminescence lifetime of 8mpTP-4mDBtPBfpm-d ₂₃ was 5.3 s. Since the wavelength of the light at which the luminescence lifetime was measured was 515 nm, it can be said that this is the luminescence lifetime of the phosphorescent component. Therefore, it was found that at low temperatures (temperatures cooled with liquid nitrogen), the phosphorescence lifetime of the deuterated product was 1.9 times longer than that of the non-deuterated product.

Here, the phosphorescence quantum yield (Φ _p ) and the phosphorescence lifetime (τ _p ) are the radiative transition rate constant k _rp and the nonradiative transition rate constant k _nrp from the lowest triplet excited state (T ₁ ) of the organic compound, From the quantum yield (Φ _isc ) of intersystem crossing from the lowest singlet excited state (S ₁ ) to the lowest triplet excited state (T ₁ ), it is expressed as the following formulas (1) and (2). be able to.

From this equation, k _rp and k _nrp can be expressed as the following equations (3) and (4) using Φ and τ, respectively.

Here, from the above measurement results, the phosphorescence quantum yield Φ _p (D) of deuterated 8mpTP-4mDBtPBfpm-d ₂₃ is equal to the phosphorescence quantum yield Φ _p (H) of non-deuterated 8mpTP-4mDBtPBfpm. It has been found that the phosphorescence lifetime τ _p (D) of 8mpTP-4mDBtPBfpm-d ₂₃ is 1.9 times the phosphorescence lifetime τ _p (H) of 8mpTP-4mDBtPBfpm. Further, the fluorescence quantum yield Φ _f (D) of 8mpTP-4mDBtPBfpm-d ₂₃ and the fluorescence quantum yield Φ _f (H) of 8mpTP-4mDBtPBfpm were almost the same.

Note that at the temperature cooled with liquid nitrogen, the rate constant of nonradiative transition of fluorescence is much smaller than the rate constant of radiative transition and _intersystem crossing. The quantum yields Φ _isc (H) and Φ _isc (D) are calculated using the fluorescence quantum yields (Φ _f (H), Φ _f (D)) of each substance,
Φ _isc (H) = 1 - Φ _f (H)
Φ _isc (D) = 1-Φ _f (D)
Since Φ _f (H) and Φ _f (D) were approximately the same value, Φ _isc (H) and Φ _isc (D) can be considered to be the same.

That is, the phosphorescence quantum yield of 8mpTP-4mDBtPBfpm is Φ _p (H), the rate constant is τ _p (H), the quantum yield of intersystem crossing is Φ _isc (H), and the rate constant of radiative transition is k _rp (H). ), the rate constant of nonradiative transition is k _nrp (H), the phosphorescence quantum yield of 8mpTP-4mDBtPBfpm-d ₂₃ is Φ _p (D), the rate constant is τ _p (D), and the quantum of intersystem crossing is When the yield is Φ _isc (D), the rate constant of radiative transition is k _rp (D), and the rate constant of non-radiative transition is k _nrp (D), k _rp (H) is expressed by the following formula (3-1). , k _rp (D) can be expressed as in the following formula (3-2), k _nrp (H) can be expressed as in the following formula (4-1), and k _nrp (D) can be expressed as in the following formula (4-2). I can do it.

Thus, k _nrp (D) is 0.50 times k _{nrp (H), k nrp (} D) < k _nrp (H), and k _rp (D) is 0.50 times k _nrp (H). 0.79 times, k _rp (D) < k _rp (H), and compared to 8mpTP-4mDBtPBfpm, the rate constant of nonradiative transition and radiative transition of deuterated 8mpTP-4mDBtPBfpm-d ₂₃ Although both rate constants were found to be small, it was found that the nonradiative transition is more suppressed than the radiative transition because the rate constant of the nonradiative transition is smaller than that of the radiative transition. Ta.

In this way, deuterated organic compounds have smaller rate constants for radiative transition and non-radiative transition, but since non-radiative transition is more suppressed, the resulting triplet excitation This allows more children to undergo radiative transitions. Radiative transition is a transition that involves energy transfer, so compared to non-deuterated organic compounds, deuterated organic compounds transfer excitation energy to other compounds (here, phosphorescence, which is the guest material). The efficiency of energy transfer to substances) is improved. By improving the energy transfer efficiency, it becomes possible to suppress the deterioration of the deuterated organic compound, and a light emitting device using the organic compound as a host material can suppress the deterioration of the host material. A light-emitting device with good reliability can be obtained.

In addition, at low temperature (temperature cooled with liquid nitrogen), the rate constant k _rp (D) of radiative transition of 8mpTP-4mDBtPBfpm-d ₂₃ is 0.79 of the rate constant k _rp (H) of radiative transition of 8mpTP-4mDBtPBfpm. However, the rate constant of non-radiative transition k _nrp (D) is 0.50 times of k _nrp (H), and relatively the rate constant of non-radiative transition k _nrp (D) decreases by a larger amount. is large. Therefore, even if the decrease in the rate constant k _rp (D) of radiative transition is taken into account, the proportion of triplet excitons that undergo radiative transition in 8mpTP-4mDBtPBfpm-d ₂₃ increases, so deuteration causes energy transfer. It can be said that efficiency improves.

Furthermore, regarding the fluorescence quantum yield, there was almost no difference between 8mpTP-4mDBtPBfpm-d ₂₃ and 8mpTP-4mDBtPBfpm. Furthermore, the rate constant of nonradiative transition at a low temperature of 77 K is very small compared to the rate constant of radiative transition and intersystem crossing. From this, there is no significant difference in the rate constants of radiative transition and non-radiative transition in the fluorescence emission process of 8mpTP-4mDBtPBfpm-d ₂₃ and 8mpTP-4mDBtPBfpm due to deuteration. It can be said that the effect mainly affects the behavior of triplet excitons.

Here, 8mpTP-4mDBtPBfpm-d ₁₃ (structural formula (223)) in which only the first substituent of 8mpTP-4mDBtPBfpm was substituted with deuterium and 8mpTP-4mDBtPBfpm-d ₁₀ (in which only the second substituent was substituted with deuterium) As a result of the same measurement for Structural Formula (225)), 8mpTP-4mDBtPBfpm-d ₁₀ (Structural Formula (225)) was equivalent to 8mpTP-4mDBtPBfpm, and 8mpTP-4mDBtPBfpm-d ₁₃ (Structural Formula (223)) showed similar results to 8mpTP-4mDBtPBfpm-d ₂₃ .

8mpTP-4mDBtPBfpm-d ₁₃ , which showed the same results as 8mpTP-4mDBtPBfpm-d ₂₃ , is an organic compound in which only the first substituent of the first organic compound is substituted with deuterium. Therefore, it has been revealed that the first organic compound can suppress the non-radiative transition in the phosphorescence process by substituting only the first substituent with deuterium. This is because in the first organic compound, _T1 is localized in the first substituent, so by deuterating the first substituent, intramolecular vibrations in the lowest triplet excited state are suppressed. This is thought to be due to the fact that the non-radiative transition from _T1 of the first organic compound can be suppressed. ) is also consistent with

Also, considering from the perspective of the energy transfer efficiency φ _ET from the host material to the guest material, the energy transfer efficiency φ _ET is expressed by the following formula (5), and in order to increase the energy transfer efficiency φ ET, the energy transfer efficiency φ _ET is It can be seen that it is sufficient if the rate constant k _h*→g becomes large and the other competing rate constants k _r +k _nr (=1/τ) become relatively small.

In Equation (5), k _r is the rate constant of the light emission process of the host material (fluorescence when discussing energy transfer from a singlet excited state, and phosphorescence when discussing energy transfer from a triplet excited state). where k _nr represents the rate constant of non-luminescent processes (thermal deactivation and intersystem crossing) of the host material, and τ represents the actually measured lifetime of the excited state of the host material. Furthermore, kh _*→g represents the rate constant of energy transfer (Förster mechanism or Dexter mechanism).

The energy transfer rate constant k _h*→g is determined by the atomic arrangement of molecules, spectral shape, etc. in organic compounds that are deuterated (8mpTP-4mDBtPBfpm-d ₂₃ ) and organic compounds that are not deuterated (8mpTP-4mDBtPBfpm). Since there is almost no difference, the two materials are almost the same (see formula (6) or (7) below). Therefore, in a comparison between deuterated organic compounds and non-deuterated organic compounds, it can be seen that the luminescence lifetime (phosphorescence lifetime) τ is greatly affected.

As mentioned above, the phosphorescence lifetime measured at low temperature (temperature cooled with liquid nitrogen) is ₁ It was .9 times higher. Assuming that there is a difference in the phosphorescence lifetime of organic compounds that are deuterated and organic compounds that are not deuterated even at room temperature, the energy transfer efficiency from the host material to the guest material _φET is determined by equation (5). A light-emitting device using an organic compound (8mpTP-4mDBtPBfpm-d ₂₃ ) that has been modified as a host material has improved energy transfer efficiency than a light-emitting device that uses an organic compound that has not been modified (8mpTP-4mDBtPBfpm) as a host material. It can be said that.

By improving energy transfer efficiency, it becomes possible to suppress deterioration of the deuterated organic compound. As a result, a light-emitting device using a deuterated organic compound as a host material has less deterioration of the host material than a light-emitting device using a non-deuterated organic compound as a host material, and has improved reliability. A good light emitting device can be obtained.

Equation (6) is the equation for the Forster mechanism, and Equation (7) is the equation for the rate constant _kh*→g of the Dexter mechanism.

In formula (6), ν represents the vibration frequency, and f′ _h (ν) is the normalized emission spectrum of the host material (fluorescence spectrum when discussing energy transfer from the singlet excited state, triplet excited state). (phosphorescence spectrum) when discussing energy transfer from a state, ε _g (ν) represents the molar extinction coefficient of the guest material, N represents Avogadro's number, n represents the refractive index of the medium, and R represents the intermolecular distance between the host material and the guest material, τ represents the actually measured lifetime of the excited state (fluorescence lifetime, phosphorescence lifetime), and φ represents the emission quantum yield (energy transfer from the singlet excited state). When discussing the energy transfer from the triplet excited state, it represents the fluorescence quantum yield, and when discussing the energy transfer from the triplet excited state, it represents the phosphorescence quantum yield), and K ² is the coefficient (0 ~4). Note that in the case of random orientation, K ² =2/3.

In formula (7), h is Planck's constant, K is a constant with energy dimension, ν represents the frequency, and f′ _h (ν) is the normalized luminescence of the host material. represents the spectrum (fluorescence spectrum when discussing energy transfer from the singlet excited state, phosphorescence spectrum when discussing energy transfer from the triplet excited state), and ε′ _g (ν) is the normalized It represents the absorption spectrum, L represents the effective molecular radius, and R represents the intermolecular distance between the host material and the guest material.

Note that when the energy of triplet excitons is high and the lifetime of the excitons is long, deterioration may be accelerated. However, in one embodiment of the present invention, since the first organic compound is a material with a relatively low T ₁ level, the longer lifetime of triplet excitons has little effect on reliability. Furthermore, since the substance in which the first substituent and the second substituent in the first organic compound (host material) are deuterated suppresses nonradiative transition, the energy transfer efficiency from the substance to the luminescent material is improved. It was found that the reliability of light emitting devices could be improved.

This example shows a detailed method for manufacturing light-emitting devices 5 to 7, which are light-emitting devices of one embodiment of the present invention, and the results of measuring their initial characteristics and reliability.

The structural formulas of the main compounds used in this example are shown below.

(Method for manufacturing light emitting device 5)
First, 50 nm of titanium (Ti), 70 nm of aluminum (Al), and 6 nm of titanium (Ti) were sequentially laminated by sputtering on a silicon substrate provided with wiring. This was heat-treated at 300° C. for 1 hour in an air atmosphere. After heat treatment and cleaning, a 10 nm film of indium tin oxide containing silicon oxide (ITSO) was formed by sputtering. This laminated film was patterned by photolithography to form a first electrode. Note that the transparent electrode functions as an anode and is regarded as a first electrode together with the reflective electrode.

Note that the area of the first electrode was 4 mm ² (2 mm x 2 mm).

Next, as a pretreatment for forming a light emitting device on the substrate, the substrate was heat treated at 120°C for 120 seconds, and then 1,1,1,3,3,3-hexamethyldisilazane (abbreviation: HMDS) ) was vaporized and sprayed for 120 seconds onto a substrate heated to 60°C. Thereby, the laminated film formed on the first electrode can be made difficult to peel off from the first electrode during the manufacturing process.

Thereafter, the substrate was introduced into a vacuum evaporation device whose internal pressure was reduced to about 1×10 ⁻⁴ Pa, and vacuum baking was performed at 170° C. for 60 minutes in the heating chamber of the vacuum evaporation device. Cooled separately.

Next, the substrate is fixed to a holder provided in a vacuum evaporation apparatus so that the surface on which the first electrode 101 is formed faces downward, and a vapor deposition method is applied to the inorganic insulating film and the first electrode 101. N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluorene represented by the above structural formula (i) -2-Amine (abbreviation: PCBBiF) and an electron acceptor material (OCHD-003) containing fluorine with a molecular weight of 672 were co-evaporated to a thickness of 10 nm at a weight ratio of 1:0.03 (=PCBBiF:OCHD-003). Then, a hole injection layer 111 was formed.

On the hole injection layer 111, PCBBiF was deposited to a thickness of 10 nm to form a hole transport layer 112.

Subsequently, 8-(1,1':4',1''-terphenyl-3-yl)-4-[3-(dibenzo Thiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm) and 9-(2-naphthyl)-9' represented by the above structural formula (iii) -phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: βNCCP) and [2-d3-methyl-8-(2-pyridinyl-κN)benzofuro] represented by the above structural formula (iv). [2,3-b]pyridine-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN2)phenyl-κC]iridium(III) (abbreviation: Ir(5mppy-d ₃ ) ₂ (mbfpypy- d ₃ )) at a weight ratio of 0.6:0.4:0.1 (=8mpTP-4mDBtPBfpm:βNCCP:Ir(5mppy-d ₃ ) ₂ (mbfpypy-d ₃ )). A light emitting layer 113 was formed by vapor deposition.

Thereafter, 2-{3-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}dibenzo[f,h ] Quinoxaline (abbreviation: 2mPCCzPDBq) is evaporated to a thickness of 10 nm to form a first electron transport layer, and 2,2′-(1,3-phenylene)bis( A second electron transport layer was formed by depositing 9-phenyl-1,10-phenanthroline (abbreviation: mPPhen2P) to a thickness of 15 nm, thereby forming the electron transport layer 114.

Subsequently, processing was performed using a photolithography method. After the substrate on which the electron transport layer 114 had been formed was taken out from the vacuum evaporation apparatus and exposed to the atmosphere, aluminum oxide was deposited to a thickness of 30 nm by ALD to form a first sacrificial layer. In forming the aluminum oxide film by the ALD method, trimethylaluminum (abbreviation: TMA) was used as a precursor and water vapor was used as an oxidizing agent.

A second sacrificial layer was formed by depositing tungsten (W) to a thickness of 54 nm on the first sacrificial layer by sputtering.

A photoresist is applied on the second sacrificial layer, exposed to light, and developed so that the processed photoresist covers the first electrode and its end is 3.5 μm wider than the end of the first electrode. It is processed so that it has a shape with a 3.0 μm wide slit located on the outside.

Using the processed photoresist as a mask, a second sacrificial layer is processed using an etching gas containing SF ₆ , and using the second sacrificial layer as a hard mask, fluoroform (CHF ₃ ), helium (He), and methane ( The first sacrificial layer was processed using an etching gas containing CH ₄ ) at a flow rate ratio of CHF ₃ :He:CH ₄ =16.5:118.5:15. Thereafter, the EL layer (hole injection layer, hole transport layer, light emitting layer, electron transport layer) was processed using an etching gas containing oxygen (O ₂ ).

After processing the EL layer, the second sacrificial layer was removed using an etching gas containing SF ₆ , leaving the first sacrificial layer. Thereafter, the first sacrificial layer was removed using an aqueous solution containing hydrofluoric acid (HF) to expose the electron transport layer.

The substrate with the second electron transport layer exposed was introduced into a vacuum evaporation device whose internal pressure was reduced to about 1×10 ⁻⁴ Pa, and vacuum baked at 70° C. for 90 minutes in a heating chamber inside the vacuum evaporation device. I did it.

Subsequently, an electron injection layer 115 is formed by co-evaporating 1.5 nm of lithium fluoride (LiF) and ytterbium (Yb) at a volume ratio of 1:0.5 (=LiF:Yb), and then, The second electrode 102 was formed by co-evaporating silver (Ag) and magnesium (Mg) at a volume ratio of 1:0.1 and a film thickness of 25 nm, and a light-emitting device of one embodiment of the present invention was manufactured. . Furthermore, a 70 nm film of indium tin oxide (ITO) was formed as a cap layer on the second electrode by sputtering.

Next, in a glove box with a nitrogen atmosphere, the light-emitting device is sealed with a glass substrate so that it is not exposed to the atmosphere (a UV-curable sealant is applied around the element, and the light-emitting device is sealed so that it is not irradiated). A light emitting device 5 was formed by irradiating only the material with UV and heat treatment at 80° C. for 1 hour under atmospheric pressure.

(Method for manufacturing light emitting device 6)
The light emitting device 6 has a light emitting layer composed of 8mpTP-4mDBtPBfpm, βNCCP, and tris{2-[5-(methyl-d ₃ )-4-phenyl-2-pyridinyl-κN represented by the above structural formula (xiv). ] phenyl-κC}iridium(III) (abbreviation: Ir(5m4dppy-d ₃ ) ₃ ) in a weight ratio of 0.6:0.4:0.1 (=8mpTP-4mDBtPBfpm:βNCCP:Ir(5m4dppy- It was produced in the same manner as light emitting device 5 except that a 40 nm film was formed by co-evaporation to obtain d ₃ ) ₃ ).

(Method for manufacturing light emitting device 7)
The light emitting device 7 replaces 8mpTP-4mDBtPBfpm in the light emitting device 6 with 8-(1,1':4',1''-terphenyl-3-yl-2,4, 5,6,2',3',5',6',2'',3'',4'',5'',6''-d ₁₃ )-4-[3-(dibenzothiophene-4 -yl-1,2,3,6,7,8,9-d ₇ ) phenyl-2,4,6-d ₃ ]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm -d ₂₃ ) was produced in the same manner as Light-emitting Device 6.

The device structures of light emitting devices 5 to 7 are shown below.

The current efficiency-luminance characteristics of the light-emitting devices 5 to 7 are shown in FIG. 42, the brightness-voltage characteristics are shown in FIG. 43, the current efficiency-current density characteristics are shown in FIG. 44, the current density-voltage characteristics are shown in FIG. 45, and the brightness- The current density characteristics are shown in FIG. 46, the electroluminescence spectrum is shown in FIG. 47, and the main initial characteristics are shown in Table 9. Note that the brightness, CIE chromaticity, and emission spectrum were measured using a spectroradiometer (SR-UL1R, manufactured by Topcon Corporation) at room temperature.

From FIGS. 42 to 47 and Table 9, it can be seen that light emitting devices 5 to 7 are all light emitting devices having good characteristics.

Next, FIG. 48 shows the results of measuring changes in brightness with respect to driving time during constant current driving at a current density of 50 mA/cm ² for Light Emitting Devices 5 to 7. From FIG. 48, it was found that all of the light emitting devices 5 to 7 were light emitting devices with good reliability, but especially the light emitting device 7 was found to be a light emitting device with a longer life.

Here, the light emitting device 5 has, in the light emitting layer, 8mpTP-4mDBtPBfpm as the first organic compound, βNCCP as the second organic compound, and Ir(5mppy-d ₃ ) ₂ (mbfpypy-d ₃ ) as the phosphorescent substance. This is a light-emitting device according to one embodiment of the present invention. Further, the light emitting device 6 according to one embodiment of the present invention has 8mpTP-4mDBtPBfpm as the first organic compound, βNCCP as the second organic compound, and Ir(5m4dppy-d ₃ ) ₃ as the phosphorescent substance in the light emitting layer. It is a light emitting device. Further, the light emitting device 7 according to the present invention has 8mpTP-4mDBtPBfpm-d ₂₃ as the first organic compound, βNCCP as the second organic compound, and Ir(5m4dppy-d ₃ ) ₃ as the phosphorescent material in the light emitting layer. 1 is a light emitting device of one embodiment.

That is, the first organic compound 8mpTP-4mDBtPBfpm or 8mpTP-4mDBtPBfpm-d ₂₃ has a benzofuropyrimidine skeleton that is a heteroaromatic ring skeleton, has a terphenyl group that is an aromatic hydrocarbon group, and has a minimum It is an organic compound whose triplet excited level is derived from a terphenyl group. Further, βNCCP, which is the second organic compound, has a bicarbazole skeleton and has a lowest triplet excitation energy of 2.55 eV (2.20 eV or more and 2.65 eV or less). Furthermore, Ir(5mppy-d ₃ ) ₂ (mbfpypy-d ₃ ) and Ir(5m4dppy-d ₃ ) ₃ are phosphorescent substances that exhibit green phosphorescence.

The lowest triplet excitation energy level (T ₁ level) of βNCCP was calculated by measuring the emission spectrum (phosphorescence spectrum) at a measurement temperature of 10 K using a thin film of βNCCP formed to a thickness of 50 nm on a quartz substrate. The measurement was performed using a microscope PL device LabRAM HR-PL (manufactured by Horiba, Ltd.) and a He-Cd laser (325 nm) as excitation light. As a result, the peak on the shortest wavelength side of the emission spectrum (phosphorescence spectrum) of βNCCP was 491 nm (2.53 eV), and the emission end on the shortest wavelength side was 486 nm (2.55 eV). Note that the emission end is defined by drawing a tangent at the value where the slope of the shortest wavelength side of the peak (or shoulder peak) observed at the shortest wavelength of the emission spectrum (phosphorescence spectrum) is maximum, and then drawing a tangent between that tangent and the horizontal axis (wavelength). Alternatively, it was calculated from the intersection with the baseline.

Note that the first organic compound and the second organic compound in the light emitting devices 5 to 7 form an exciplex capable of exciting the green phosphorescent substance. Moreover, since the second organic compound has a relatively low _T1 level of 2.55 eV, excitons in an excessively high energy state are not generated. Also, in the first organic compound, the lowest triplet excited level is present in the terphenyl group (especially preferably a terphenyl group substituted at the meta position), so that the T ₁ level is the same as in the second organic compound. The value is moderate, not too high. From this, light emitting devices 5 to 7 were able to be light emitting devices with good reliability.

When the lowest triplet excitation energy level (T ₁ level) of 8mpTP-4mDBtPBfpm and 8mpTP-4mDBtPBfpm-d ₂₃ was measured using the same method as βNCCP, it was found that The peak was 500 nm (2.48 eV), and the emission end on the shortest wavelength side was 486 nm (2.55 eV). Furthermore, the peak on the shortest wavelength side of the emission spectrum of 8mpTP-4mDBtPBfpm-d ₂₃ was 501 nm (2.48 eV), and the emission end on the shortest wavelength side was 484 nm (2.56 eV).

100A Display device 100B Display device 100C Display device 100D Display device 100E Display device 100 Display device 101 First electrode 102 Second electrode 103B EL layer 103Bf EL film 103G EL layer 103Gf EL film 103R EL layer 103Rf EL film 103 EL layer 104 Common layer 105 Insulator 110B Subpixel 110G Subpixel 110R Subpixel 110 Subpixel 111 Hole injection layer 112B Conductive layer 112R Conductive layer 112 Hole transport layer 113 Light emitting layer 114 Electron transport layer 115 Electron injection layer 116 Charge generation layer 117 P Mold layer 118 Electronic relay layer 119 N-type layer 120 Substrate 122 Resin layer 125f Inorganic insulating film 125 Inorganic insulating layer 126B Conductive layer 126R Conductive layer 127a Insulating layer 127f Insulating film 127 Insulating layer 128 Layer 129B Conductive layer 129R Conductive layer 130B Light emitting device 130G Light emitting device 130R Light emitting device 130 Light emitting device 131 Protective layer 132B Colored layer 132G Colored layer 132R Colored layer 140 Connection portion 141 Region 142 Adhesive layer 151B Conductive layer 151C Conductive layer 151cf Conductive film 151f Conductive film 151G Conductive layer 151R Conductive layer 151 Conductive layer 152B Conductive layer 152C Conductive layer 152f Conductive film 152G Conductive layer 152R Conductive layer 152 Conductive layer 153 Insulating layer 155 Common electrode 156B Insulating layer 156C Insulating layer 156f Insulating film 156G Insulating layer 156R Insulating layer 156 Insulating layer 157 Light shielding layer 158B Sacrificial layer 158Bf Sacrificial film 158f Sacrificial film 158G Sacrificial layer 158Gf Sacrificial film 158R Sacrificial layer 158Rf Sacrificial film 159B Mask layer 159Bf Mask film 159G Mask layer 159Gf Mask film 159R Mask layer 159Rf Mask film 166 Conductive layer 171 Insulating layer 172 Conductive layer 173 Insulating layer 174 Insulating layer 175 Insulating Layer 176 Plug 177 Pixel portion 178 Pixel 179 Conductive layer 190B Resist mask 190G Resist mask 190R Resist mask 191 Resist mask 201 Transistor 204 Connection portion 205 Transistor 211 Insulating layer 213 Insulating layer 214 Insulating layer 215 Insulating layer 221 Conductive layer 222a Conductive layer 222b Conductive Layer 223 Conductive layer 224B Conductive layer 224C Conductive layer 224G Conductive layer 224R Conductive layer 231 Semiconductor layer 240 Capacitor 241 Conductive layer 242 Connection layer 243 Insulating layer 245 Conductive layer 254 Insulating layer 255 Insulating layer 256 Plug 261 Insulating layer 271 Plug 280 Display module 281 Display section 282 Circuit section 283a Pixel circuit 283 Pixel circuit section 284a Pixel 284 Pixel section 285 Terminal section 286 Wiring section 290 FPC
291 Substrate 292 Substrate 301 Substrate 310 Transistor 311 Conductive layer 312 Low resistance region 313 Insulating layer 314 Insulating layer 315 Element isolation layer 317 Light shielding layer 351 Substrate 352 Substrate 353 FPC
354 IC
355 Wiring 356 Circuit 501 First electrode 502 Second electrode 511 First light emitting unit 512 Second light emitting unit 513 Charge generation layer 601 Drive circuit 602 Pixel portion 603 Gate line drive circuit 604 Sealing substrate 605 Sealing material 607 Space 608 Leading wiring 610 Element board 611 Switching FET
612 Current control FET
613 First electrode 614 Insulator 616 EL layer 617 Second electrode 618 Light emitting device 623 FET
700A Electronic device 700B Electronic device 721 Housing 723 Mounting section 727 Earphone section 750 Earphone 751 Display panel 753 Optical member 756 Display area 757 Frame 758 Nose pad 800A Electronic device 800B Electronic device 820 Display section 821 Housing 822 Communication section 823 Mounting section 824 Control unit 825 Imaging unit 827 Earphone unit 832 Lens 6500 Electronic device 6501 Housing 6502 Display unit 6503 Power button 6504 Button 6505 Speaker 6506 Microphone 6507 Camera 6508 Light source 6510 Protective member 6511 Display panel 6512 Optical member 6513 Touch sensor panel 6515 FPC
6516 IC
6517 Printed Retail 6518 Battery 7000 Battery 7100 Television Equipment 7100 television device 7151 Remote control operating machine 7171 Changing 7200 Notebook type personal computer 7211 Chant 7212 Keyboard 7213 Pointing Device 7214 External connection 7214 external connection Port 7300 Digital Signage 7301 Circular 7303 Speech 7311 Information Terminal 7400 Digital signage 7401 Pillar 7411 Information terminal 9000 Housing 9001 Display section 9002 Camera 9003 Speaker 9005 Operation key 9006 Connection terminal 9007 Sensor 9008 Microphone 9050 Icon 9051 Information 9052 Information 9053 Information 9054 Information 9055 Hinge 9171 Mobile information terminal 9 172 Mobile information terminal 9173 Tablet terminal 9200 Mobile information terminal 9201 Mobile information terminal

Claims (14)

a first electrode;
a second electrode;
having a light emitting layer;
The light emitting layer is located between the first electrode and the second electrode,
The light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent substance,
The first organic compound has a heteroaromatic ring skeleton and an aromatic hydrocarbon group,
The second organic compound has a bicarbazole skeleton,
the lowest triplet excited state of the first organic compound is localized in the aromatic hydrocarbon group;
A light emitting device in which the energy of the lowest triplet excited level of the second organic compound is 2.20 eV or more and 2.65 eV or less. a first electrode;
a second electrode;
having a light emitting layer;
the light emitting layer is located between the first electrode and the second electrode,
The light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent substance,
The first organic compound has a heteroaromatic ring skeleton and a substituent,
The substituent has a 1,1′:4′,1″-terphenyl skeleton,
The second organic compound has a bicarbazole skeleton,
A light emitting device, wherein the energy of the lowest triplet excited level of the second organic compound is 2.20 eV or more and 2.65 eV or less. In claim 2,
A light emitting device in which the substituent includes one or both of a dibenzofuran skeleton and a dibenzothiophene skeleton. 4. The light emitting device according to claim 3, wherein the 1,1':4',1''-terphenyl skeleton is substituted with the heteroaromatic ring skeleton at the 3-position. 4. The light emitting device according to claim 3, wherein the substituent is substituted on the heteroaromatic ring skeleton via a 1,3-phenylene group. a first electrode;
a second electrode;
having a light emitting layer;
the light emitting layer is located between the first electrode and the second electrode,
The light-emitting layer includes a first organic compound, a second organic compound, and a phosphorescent substance,
The first organic compound has a heteroaromatic ring skeleton and a 1,1':4',1''-terphenyl group,
The second organic compound has a bicarbazole skeleton,
A light emitting device, wherein the energy of the lowest triplet excited level of the second organic compound is 2.20 eV or more and 2.65 eV or less. In claim 6,
A light emitting device, wherein the 1,1':4',1''-terphenyl group is substituted on the heteroaromatic ring skeleton at the 3-position. In claim 6,
A light emitting device in which the 1,1':4',1''-terphenyl group is substituted on the heteroaromatic ring skeleton via a 1,3-phenylene group. In any one of claims 1 to 8,
A light emitting device in which the heteroaromatic ring skeleton includes a fused ring. In any one of claims 1 to 8,
A light emitting device in which the heteroaromatic ring skeleton includes a diazine skeleton. In any one of claims 1 to 8,
A light emitting device in which the heteroaromatic ring skeleton includes a fused ring and a diazine skeleton. In any one of claims 1 to 8,
A light emitting device in which the heteroaromatic ring skeleton has a benzofuropyrimidine skeleton or a triazine skeleton. In any one of claims 1 to 8,
A light emitting device in which the second organic compound has a naphthyl group. In any one of claims 1 to 8,
A light emitting device in which the lowest triplet excitation level of the first organic compound originates only from the substituent.

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