Light-emitting device

Abstract

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

Description

[Technical field]

[0001] One aspect of the invention relates to a light emitting device.

[0002] Note that one embodiment of the present invention is not limited to the above technical field. Examples of the technical field of one embodiment of the present invention include a semiconductor device, a display device, a light-emitting device, a power storage device, a memory device, an electronic device, a lighting device, an input device (e.g., a touch sensor), an input / output device (e.g., a touch panel), a driving method thereof, or a manufacturing method thereof. [Background technology]

[0003] In recent years, display devices are expected to be used in various applications. For example, applications of large display devices include home television devices (also called televisions or television receivers), digital signage, and public information displays (PIDs). In addition, development of smartphones and tablet terminals equipped with touch panels as mobile information terminals is underway.

[0004] At the same time, there is also a demand for higher resolution display devices. Devices requiring high resolution display devices include, for example, devices for virtual reality (VR), augmented reality (AR), substitutional reality (SR), and mixed reality (MR), and high resolution display devices for use in these devices are being actively developed.

[0005] As a display device suitable for such high-definition display devices, light-emitting devices using organic compounds have been actively researched. Light-emitting devices (also called organic EL devices or organic EL elements) that utilize the electroluminescence (hereinafter referred to as EL) phenomenon of organic compounds have features such as being easily thin and lightweight, being capable of high-speed response to input signals, and being capable of being driven by a DC constant voltage power supply, and are therefore applied to display devices.

[0006] Displays and lighting devices using such light-emitting devices are suitable for a variety of electronic devices, but research and development is ongoing to find light-emitting devices with even better characteristics.

[0007] In particular, the lifetime of a light-emitting device is an important characteristic that affects the usage period, display quality, and power consumption of the electronic devices. Patent Document 1 discloses a configuration that can improve the luminous efficiency, lifetime, and driving voltage of a phosphorescent light-emitting device by using an exciplex as an energy donor. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2012-186461 A [Non-patent literature]

[0009] [Non-Patent Document 1] Nicholas J. Turro, V. Ramamurthy, JC Scaiano, “MODERN MOLECULAR PHOTOCHEMISTRY OF ORGANIC MOLECULES”, UNIVERSITY SCIENCE BOOKS, February 10, 2010, pp. 204-208 [Non-Patent Document 2] 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 Summary of the Invention [Problem to be solved by the invention]

[0010] An object of one embodiment of the present invention is to provide a light-emitting device with good reliability.Another object of one embodiment of the present invention is to provide a light-emitting device which emits light efficiently and has good reliability.Another object of one embodiment of the present invention is to provide a green phosphorescent light-emitting device with good reliability.Another object of one embodiment of the present invention is to provide a green phosphorescent light-emitting device which emits light efficiently and has good reliability.

[0011] Another object of one embodiment of the present invention is to provide a display device with high reliability. Another object of one embodiment of the present invention is to provide a display device with low power consumption and high reliability.

[0012] Alternatively, it is an object of the present invention to provide a novel organic compound, a novel light-emitting device, a novel display device, a novel display module, and a novel electronic device.

[0013] Note that the description of these problems does not preclude the existence of other problems. One embodiment of the present invention does not necessarily have to solve all of these problems. Problems other than these can be extracted from the description of the specification, drawings, and claims. [Means for solving the problem]

[0014] One embodiment of the present invention is a light-emitting device comprising a first electrode, a second electrode, and a light-emitting layer, the light-emitting layer being located between the first electrode and the second electrode, the light-emitting layer comprising a first organic compound, a second organic compound, and a phosphorescent material, the first organic compound having a heteroaromatic ring skeleton and an aromatic hydrocarbon group, the second organic compound having a bicarbazole skeleton, a lowest triplet excited state of the first organic compound being localized in the aromatic hydrocarbon group, and energy of the lowest triplet excited level of the second organic compound being 2.20 eV or more and 2.65 eV or less.

[0015] Another embodiment of the present invention is a light-emitting device comprising a first electrode, a second electrode, and a light-emitting layer, the light-emitting layer being located between the first electrode and the second electrode, the light-emitting layer comprising a first organic compound, a second organic compound, and a phosphorescent material, the first organic compound having a heteroaromatic ring skeleton and a substituent, the substituent having a 1,1':4',1''-terphenyl skeleton, the second organic compound having a bicarbazole skeleton, and the energy of a lowest triplet excitation level of the second organic compound is 2.20 eV or more and 2.65 eV or less.

[0016] 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.

[0017] Alternatively, another embodiment of the present invention is a light-emitting device having the above-described structure, in which the substituent is substituted at a meta position on the heteroaromatic ring skeleton.

[0018] Alternatively, another embodiment of the present invention is a light-emitting device having the above-described structure, in which the substituent is substituted on the heteroaromatic ring skeleton via a 1,3-phenylene group.

[0019] Alternatively, another embodiment of the present invention is a light-emitting device comprising a first electrode, a second electrode, and a light-emitting layer, the light-emitting layer being located between the first electrode and the second electrode, the light-emitting layer comprising a first organic compound, a second organic compound, and a phosphorescent light-emitting material, the first organic compound having a heteroaromatic ring skeleton and a 1,1':4',1''-terphenyl group, the second organic compound having a bicarbazole skeleton, and the energy of a lowest triplet excitation level of the second organic compound being 2.20 eV or more and 2.65 eV or less.

[0020] Alternatively, another aspect of the present invention is a light-emitting device having the above-mentioned structure, wherein the 1,1':4',1''-terphenyl group is substituted at a meta position on the heteroaromatic ring skeleton.

[0021] Alternatively, another aspect of the present invention is a light-emitting device having the above-mentioned structure, wherein the 1,1':4',1''-terphenyl group is substituted on the heteroaromatic ring skeleton via a 1,3-phenylene group.

[0022] Another embodiment of the present invention is a light-emitting device having the above structure, in which the heteroaromatic ring skeleton includes a fused ring.

[0023] Another embodiment of the present invention is a light-emitting device having the above structure, in which the heteroaromatic ring skeleton includes a diazine skeleton.

[0024] Another embodiment of the present invention is a light-emitting device having the above structure, in which the heteroaromatic ring skeleton includes a fused ring and a diazine skeleton.

[0025] Another embodiment 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.

[0026] Another embodiment of the present invention is a light-emitting device having the above structure, in which the second organic compound has a naphthyl group.

[0027] Another embodiment 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 is derived only from the substituent.

[0028] Another embodiment of the present invention is a display module including the above-described light-emitting device and at least one of a connector and an integrated circuit.

[0029] Another embodiment of the present invention is an electronic device including any of the above light-emitting devices and at least one of a housing, a battery, a camera, a speaker, and a microphone. Effect of the Invention

[0030] According to one embodiment of the present invention, a light-emitting device having good reliability can be provided. According to another embodiment of the present invention, a light-emitting device which emits light efficiently and has good reliability can be provided. According to another embodiment of the present invention, a green phosphorescent light-emitting device which emits light efficiently and has good reliability can be provided. According to another embodiment of the present invention, a green phosphorescent light-emitting device which emits light efficiently and has good reliability can be provided.

[0031] According to one embodiment of the present invention, a highly reliable display device can be provided. According to one embodiment of the present invention, a display device with low power consumption and high reliability can be provided.

[0032] Alternatively, a novel organic compound, a novel light-emitting device, a novel display device, a novel display module, and a novel electronic device can be provided.

[0033] Note that the description of these effects does not preclude the existence of other effects. One embodiment of the present invention does not necessarily have all of these effects. Effects other than these can be extracted from the description in the specification, drawings, and claims. [Brief description of the drawings]

[0034] [Figure 1]1A to 1C are schematic diagrams of a light-emitting device according to one embodiment of the present invention. [Diagram 2] 2A and 2B are diagrams illustrating a display device according to one embodiment of the present invention. [Diagram 3] 3(A) and 3(B) are diagrams illustrating a display device according to one embodiment of the present invention. [Figure 4] 4A to 4E are cross-sectional views showing an example of a method for manufacturing a display device. [Diagram 5] 5A to 5D are cross-sectional views showing an example of a method for manufacturing a display device. [Figure 6] 6A to 6D are cross-sectional views showing an example of a method for manufacturing a display device. [Figure 7] 7A to 7C are cross-sectional views showing an example of a method for manufacturing a display device. [Figure 8] 8A to 8C are cross-sectional views showing an example of a method for manufacturing a display device. [Figure 9] 9A to 9C are cross-sectional views showing an example of a method for manufacturing a display device. [Figure 10] 10A and 10B are perspective views showing a configuration example of a display module. [Figure 11] 11A and 11B are cross-sectional views showing a configuration example of a display device. [Figure 12] FIG. 12 is a perspective view showing a configuration example of a display device. [Figure 13] FIG. 13 is a cross-sectional view showing a configuration example of a display device. [Figure 14] FIG. 14 is a cross-sectional view showing a configuration example of a display device. [Figure 15] FIG. 15 is a cross-sectional view showing a configuration example of a display device. [Figure 16] 16A to 16D are diagrams illustrating examples of electronic devices. [Figure 17] 17A to 17F are diagrams illustrating examples of electronic devices. [Figure 18]18A to 18G are diagrams illustrating examples of electronic devices. [Figure 19] FIG. 19 is a graph showing the luminance-current density characteristics of the light-emitting device 1 and the comparative light-emitting device 1. As shown in FIG. [Figure 20] FIG. 20 is a graph showing the current efficiency-luminance characteristics of the light-emitting device 1 and the comparative light-emitting device 1. In FIG. [Figure 21] FIG. 21 is a graph showing the luminance-voltage characteristics of the light-emitting device 1 and the comparative light-emitting device 1. As shown in FIG. [Figure 22] FIG. 22 is a graph showing the current density-voltage characteristics of the light-emitting device 1 and the comparative light-emitting device 1. As shown in FIG. [Diagram 23] FIG. 23 shows the emission spectra of the light-emitting device 1 and the comparative light-emitting device 1. As shown in FIG. [Figure 24] FIG. 24 is a graph showing the normalized luminance-time change characteristics of the light-emitting device 1 and the comparative light-emitting device 1. In FIG. [Diagram 25] 25(A) to 25(C) are diagrams showing the analytical results based on the calculation of 8mpTP-4mDBtPBfpm. [Figure 26] 26(A) to 26(C) are diagrams showing the analysis results by calculation of the organic compound represented by the structural formula (216). [Figure 27] 27(A) to 27(C) are diagrams showing the analysis results based on the calculation of 8BP-4mDBtPBfpm. [Figure 28] FIG. 28 is a graph showing the luminance-current density characteristics of the light-emitting device 2 and the comparative light-emitting device 2. As shown in FIG. [Figure 29] FIG. 29 is a graph showing the current efficiency-luminance characteristics of the light-emitting device 2 and the comparative light-emitting device 2. As shown in FIG. [Diagram 30] FIG. 30 is a graph showing the luminance-voltage characteristics of the light-emitting device 2 and the comparative light-emitting device 2. As shown in FIG. [Diagram 31] FIG. 31 is a graph showing the current density-voltage characteristics of the light-emitting device 2 and the comparative light-emitting device 2. As shown in FIG. [Diagram 32] FIG. 32 is a graph showing the emission spectra of the light-emitting device 2 and the comparative light-emitting device 2. As shown in FIG. [Diagram 33] FIG. 33 is a graph showing the normalized luminance-time change characteristics of the light-emitting device 2 and the comparative light-emitting device 2. In FIG. [Diagram 34] FIG. 34 is a graph showing the luminance-current density characteristics of the light-emitting device 3 and the light-emitting device 4. As shown in FIG. [Diagram 35] FIG. 35 is a graph showing the current efficiency-luminance characteristics of the light-emitting device 3 and the light-emitting device 4. As shown in FIG. [Diagram 36] FIG. 36 is a diagram showing the luminance-voltage characteristics of the light-emitting device 3 and the light-emitting device 4. As shown in FIG. [Figure 37] FIG. 37 is a graph showing the current density-voltage characteristics of the light-emitting device 3 and the light-emitting device 4. As shown in FIG. [Figure 38] FIG. 38 shows the emission spectra of the light-emitting device 3 and the light-emitting device 4. As shown in FIG. [Figure 39] FIG. 39 is a graph showing the normalized luminance-time change characteristics of the light-emitting device 3 and the light-emitting device 4. As shown in FIG. [Diagram 40] FIG. 40 is a diagram showing the results of measuring the emission spectra of 8mpTP-4mDBtPBfpm and 8mpTP-4mDBtPBfpm-d23 at low temperatures. [Diagram 41] FIG. 41 is a diagram showing the measurement results of the luminescence lifetimes of 8mpTP-4mDBtPBfpm and 8mpTP-4mDBtPBfpm-d23 at low temperatures. [Diagram 42] FIG. 42 is a graph showing the current efficiency-luminance characteristics of light-emitting devices 5 to 7. In FIG. [Diagram 43] FIG. 43 is a diagram showing the luminance-voltage characteristics of light-emitting devices 5 to 7. In FIG. [Diagram 44] FIG. 44 is a graph showing the current efficiency-current density characteristics of light-emitting devices 5 to 7. In FIG. [Diagram 45] FIG. 45 is a graph showing the current density-voltage characteristics of light-emitting devices 5 to 7. In FIG. [Figure 46] FIG. 46 is a graph showing the luminance-current density characteristics of light-emitting devices 5 to 7. In FIG. [Figure 47]FIG. 47 shows electroluminescence spectra of light-emitting devices 5 to 7. As shown in FIG. [Figure 48] FIG. 48 is a graph showing the normalized luminance-time change characteristics of light-emitting devices 5 to 7. In FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] The embodiments will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it will be easily understood by those skilled in the art that the modes and details of the present invention can be modified 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 description of the embodiments shown below.

[0036] In this specification, etc., a device fabricated using a metal mask or an FMM (fine metal mask, high-definition metal mask) may be referred to as a device with an MM (metal mask) structure. In addition, in this specification, etc., a device fabricated without using a metal mask or an FMM may be referred to as a device with an MML (metal maskless) structure.

[0037] (Embodiment 1) Phosphorescent light-emitting devices basically emit light from the lowest triplet excitation level (T1 level), which is located at a lower energy level than the lowest singlet excitation level (S1 level). Therefore, it is necessary to use materials with a wider energy gap between the highest occupied molecular orbital (HOMO: Highest Occupied Molecular Orbital) level and the lowest unoccupied molecular orbital (LUMO: Lowest Unoccupied Molecular Orbital) level (HOMO-LUMO energy gap) than fluorescent light-emitting devices that emit light of the same color.

[0038] In addition, in the case of a configuration in which an exciplex is used as an energy donor to excite a phosphorescent material (ExTET: Exciplex-Triplet Energy Transfer), it is preferable that the S1 level of the exciplex is equal to or higher than the T1 level of the phosphorescent material (the S1 level and T1 level of the exciplex are close to each other). It is also preferable that the T1 level of each of the multiple compounds forming the exciplex is equal to or higher than the T1 level of the phosphorescent material.

[0039] In a light-emitting device having an ExTET structure, an exciplex for providing energy to a phosphorescent material is preferably formed from an organic compound having an electron transport property and an organic compound having a hole transport property, and the HOMO-LUMO energy gap of the exciplex corresponds to the energy gap between the LUMO level of the organic compound having an electron transport property and the HOMO level of the organic compound having a hole transport property.

[0040] In this case, in the organic compound having an electron transport property and the organic compound having a hole transport property that form the exciplex, the HOMO level of the organic compound having an electron transport property is lower than the HOMO level of the organic compound having a hole transport property, and the LUMO level of the organic compound having a hole transport property is higher than the LUMO level of the organic compound having an electron transport property. Therefore, the HOMO-LUMO energy gap of each of the organic compound having an electron transport property and the organic compound having a hole transport property that form the exciplex is necessarily larger than the HOMO-LUMO energy gap of the exciplex.

[0041] Here, it is believed that the generation of exciplexes in light-emitting devices is dominated by a process (electroplex process) in which an anion of an organic compound with electron transport properties and a cation of an organic compound with hole transport properties come into close proximity to directly form an exciplex. In addition, even if one of the organic compound with electron transport properties and the organic compound with hole transport properties becomes excited, it quickly interacts with the other to form an exciplex. Therefore, most of the excitons in the light-emitting layer are believed to exist as exciplexes, and no attention has been paid to the S1 and T1 levels of the organic compound itself that forms the exciplex.

[0042] However, the present inventors have found that when an emitting layer is formed using an organic compound having electron transport properties and an organic compound having hole transport properties, each triplet excitation energy affects the reliability of a phosphorescent light-emitting device. This is believed to be because a process in which each of the T1 levels is generated from the T1 level of the exciplex may occur in the device.

[0043] In addition, regarding the S1 level or T1 level of an organic compound, when a ν=0→ν=0 transition (0→0 band) between the ground state and excited state vibrational levels is clearly observed in the fluorescence spectrum or phosphorescence spectrum, it is preferable to calculate using the 0→0 band (see, for example, Non-Patent Document 1). In addition, when the 0→0 band is not clear, a tangent line is drawn at the value where the slope of the short wavelength side of the peak in the fluorescence spectrum is maximum, and the energy of the wavelength at the intersection of the tangent line with the horizontal axis (wavelength) or the baseline is taken as the S1 level, and a tangent line is drawn at the value where the slope of the short wavelength side of the peak in the phosphorescence spectrum is maximum, and the energy of the wavelength at the intersection of the tangent line with the horizontal axis (wavelength) or the baseline is taken as the T1 level (see, for example, Non-Patent Document 2). In this specification, the measurement of each level is performed using the latter method. In addition, when comparing levels, the comparison is performed at levels calculated by the same method.

[0044] 1A, a light-emitting device of one embodiment of the present invention has a light-emitting layer 113 between at least a first electrode 101 and a second electrode 102. The light-emitting layer 113 includes a phosphorescent substance, a first organic compound, and a second organic compound.

[0045] The first organic compound is an organic compound having electron transport properties. The first organic compound has a heteroaromatic ring skeleton and a first substituent substituted on the heteroaromatic ring skeleton. In one embodiment of the present invention, the first organic compound is an organic compound in which the lowest triplet excited state is localized in the first substituent and the lowest triplet excited level (T1 level) is derived from the first substituent. That is, this means that the first substituent has the lowest T1 level in the skeleton or group constituting the first organic compound. In other words, it can be said that the lowest triplet excited state T1 (i.e., triplet exciton) of the first organic compound is distributed (or localized) in the first substituent.

[0046] 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 contains a diazine skeleton or a triazine skeleton, and more preferably contains a diazine skeleton.

[0047] In addition, the heteroaromatic ring skeleton preferably contains a condensed ring, and when a hydrocarbon such as a benzene ring is condensed to the heteroaromatic ring, the condensed ring is also included in the heteroaromatic ring. That is, both a monocyclic heteroaromatic ring (e.g., a triazine ring) and a condensed heteroaromatic ring (e.g., a quinoxaline ring, a 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 contains a benzofuropyrimidine skeleton or a benzothienopyrimidine skeleton.

[0048] 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).

[0049] [ka]

[0050] The first substituent in the first organic compound is preferably an aromatic hydrocarbon group or a heteroaromatic ring group, provided that the first substituent has at least a 1,1':4',1''-terphenyl skeleton, and the 1,1':4',1''-terphenyl skeleton is bonded to the heteroaromatic ring skeleton at the meta-position or ortho-position, i.e., the 3-position or 2-position, of a terminal benzene ring, or the 1,1':4',1''-terphenyl skeleton is bonded to the heteroaromatic ring skeleton via a 1,3-phenylene group or a 1,2-phenylene group.

[0051] In the above 1,1':4',1"-terphenyl skeleton, of the three benzene rings bonded to each other at the para position, in two adjacent benzene rings, the carbons adjacent to the bonded carbon may be crosslinked by any of oxygen, sulfur, and carbon. In other words, the first substituent may have a dibenzothiophene skeleton, a dibenzofuran skeleton, or a fluorene skeleton, and the above 1,1':4',1"-terphenyl skeleton preferably contains a dibenzothiophene skeleton, a dibenzofuran skeleton, or a fluorene skeleton.

[0052] 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.

[0053] Specifically, the first substituent in the first organic compound is preferably a skeleton represented by any one of the following structural formulas (S1-1) to (S1-24).

[0054] [ka]

[0055] In addition, when the heteroaromatic ring skeleton has a fused ring and a ring composed only of carbon is present as a part of the fused ring, the first substituent is preferably substituted on the ring composed only of carbon.

[0056] In addition to the heteroaromatic ring skeleton and the first substituent, the first organic compound preferably has one or two second substituents having a hole transporting property.

[0057] The second substituent is preferably a group represented by the following general formulae (Ht-1) to (Ht-15).

[0058] [ka]

[0059] In the above general formulas (Ht-1) to (Ht-15), Q represents oxygen or sulfur. 10 represents a substituted or unsubstituted aryl group having 6 to 13 carbon atoms.

[0060] The second substituent is preferably bonded to the heteroaromatic ring skeleton via a phenylene group, which is preferably a 1,3-phenylene group or a 1,2-phenylene group, more preferably a 1,3-phenylene group.

[0061] In addition, when the heteroaromatic ring skeleton has a condensed ring and a ring composed only of carbon is present as a part of the condensed ring, the second substituent or the phenylene group to which the second substituent is bonded is preferably substituted with a ring containing a heteroatom (particularly a ring containing nitrogen, such as a diazine ring).

[0062] Note that in the first organic compound, some or all of the hydrogen atoms in the first organic compound may be deuterium.

[0063] Specifically, the first organic compound is preferably an organic compound represented by the following structural formulas (200) to (225).

[0064] [ka]

[0065] [ka]

[0066] The first organic compound may further have a substituent in place of hydrogen or deuterium, and the substituent is preferably an alkyl group having 1 to 6 carbon atoms or a phenyl group.

[0067] The second organic compound is an organic compound having a hole transporting property. The second organic compound has a bicarbazole skeleton and a T1 level of 2.20 eV to 2.65 eV, preferably 2.50 eV to 2.60 eV.

[0068] As described above, the second organic compound is an organic compound having a bicarbazole skeleton, particularly a 3,3'-bicarbazole skeleton, and particularly preferably an organic compound having a 9,9'-diaryl-9H,9'H-3,3'-bicarbazole skeleton. However, the second organic compound is an organic compound having a T1 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 T1 level of 9,9'-diphenyl-9H,9'H-3,3'-bicarbazole (PCCP) is 2.73 eV, but by lowering the T1 level compared to PCCP while maintaining the same 9,9'-diaryl-9H,9'H-3,3'-bicarbazole skeleton as PCCP, the light-emitting device according to one embodiment of the present invention can be a long-life light-emitting device. However, in consideration of exciting a green to yellow phosphorescent light-emitting material, the T1 level is preferably 2.20 eV or more.

[0069] The second organic compound preferably has an aromatic hydrocarbon group, and more preferably has 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. In addition, the lowest triplet excitation level of the second organic compound is preferably derived from the aromatic hydrocarbon group.

[0070] 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 7th position of a carbazole skeleton, such as the organic compound shown in the following structural formula (304), and an organic compound having a parabiphenyl group at the 6th position of a carbazole skeleton, such as the organic compound shown in the following structural formula (303). In addition, the lowest triplet excitation level of the second organic compound is preferably derived from the 1,1':4',1''-terphenyl skeleton.

[0071] As the second organic compound, for example, organic compounds represented by the following structural formulas (300) to (305) can be used.

[0072] [ka]

[0073] It is preferable that the first organic compound and the second organic compound are a combination capable of forming an exciplex capable of exciting the phosphorescent material. The exciplex of the first organic compound and the second organic compound serves as an energy donor for the phosphorescent material, thereby achieving effects such as improved energy transfer efficiency and reduced driving voltage.

[0074] In this case, the S1 level of the exciplex is equal to or higher than the T1 level of the phosphorescent material (the S1 level and the T1 level of the exciplex are close to each other). In order to reduce the driving voltage, it is preferable that the difference between the S1 level of the exciplex and the T1 level of the phosphorescent material is 0.20 eV or less.

[0075] 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 that exhibits such phosphorescence may be used, but it is preferable to use, for example, an organometallic complex such as the following.

[0076] 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-tert-butyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)2(acac)]), (acetylacetonato)bis[6-(2-norbornyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(nbppm)2(acac)]), (acetylacetonato)bis[5-methyl-6-( Organometallic iridium complexes having a pyrimidine skeleton, such as (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-Me)2(acac)]) and (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-iPr)2(acac)]); organometallic iridium complexes having a pyrazine skeleton, such as tris(2-phenylpyridinato-N,C 2′ ) Iridium(III) (abbreviation: [Ir(ppy)3]), bis(2-phenylpyridinato-N,C 2′)iridium(III) acetylacetonate (abbreviation: [Ir(ppy)2(acac)]), bis(benzo[h]quinolinato)iridium(III) acetylacetonate (abbreviation: [Ir(bzq)2(acac)]), tris(benzo[h]quinolinato)iridium(III) (abbreviation: [Ir(bzq)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-d3-methyl-8-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(5-d3-methyl-2-pyridyl-κN2)phenyl-κ]iridium(III) (abbreviation: [Ir(5mppy-d3)2(mbfpypy-d3)]), [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-d3)]), [2-(4-d3-methyl-5-phenyl-2-pyridinyl-κN2)phenyl-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN2)phenyl In addition to organometallic iridium complexes having a pyridine skeleton such as [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)]), rare earth metal complexes such as tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviation: [Tb(acac)3(Phen)]) can be mentioned. These are compounds that mainly exhibit yellow to green phosphorescence, and have emission peaks in the wavelength range of 470 nm to 570 nm. In addition, organometallic iridium complexes having a pyrimidine skeleton are particularly preferred because they are remarkably excellent in reliability or luminous efficiency. In addition, organometallic iridium complexes having ligands substituted with deuterium are particularly preferred because they are highly reliable when used together with the first organic compound and the second organic compound.

[0077] A light-emitting device according to one embodiment of the present invention having such a structure can be a phosphorescent light-emitting device with long lifetime and high reliability.

[0078] Next, the configuration of the light emitting device will be described in detail.

[0079] 1 is a schematic diagram of a light-emitting device according to one embodiment of the present invention. A first electrode 101 is provided on an insulator 105, and an EL layer 103 is provided between the first electrode 101 and a second electrode 102. The EL layer includes at least a light-emitting layer 113. The first electrode is independent for each light-emitting device, and the second electrode is formed as a layer shared among a plurality of light-emitting devices.

[0080] 1(A), the EL layer 103 preferably further includes 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. The EL layer 103 may further 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 generating layer. Conversely, any of the above-mentioned layers may not be provided.

[0081] The light-emitting layer 113 of the EL layer 103 of the light-emitting device includes a phosphorescent material, a first organic compound, and a second organic compound, as described in Embodiment 1. The phosphorescent material, the first organic compound, and the second organic compound have been described in detail in Embodiment 1, so that repeated description will be omitted. See Embodiment 1.

[0082] In this embodiment, the first electrode 101 is described as an electrode including an anode, and the second electrode 102 is described as an electrode including a cathode, but this may be reversed. The first electrode 101 and the second electrode 102 are formed as a single-layer structure or a laminated structure, and in the case of a laminated structure, the layer in contact with the EL layer 103 functions as an anode or a cathode. In the case of an electrode having a laminated structure, there is no restriction on the work function of layers other than the layer in contact with the EL layer 103, and materials may be selected according to required characteristics such as resistance value, processing convenience, reflectance, light transmittance, and stability.

[0083] The anode is preferably formed using a metal, alloy, conductive compound, or mixture thereof having a large work function (specifically, 4.0 eV or more). Specific examples include indium oxide-tin oxide (ITO), indium oxide-tin oxide containing silicon or silicon oxide (ITSO), indium oxide-zinc oxide, and indium oxide containing tungsten oxide and zinc oxide (IWZO). These conductive metal oxide films are usually formed by a sputtering method, but may also be formed by applying a sol-gel method or the like. As an example of a method for forming indium oxide-zinc oxide, a method for forming indium oxide-zinc oxide by a sputtering method using a target in which 1 to 20 wt % of zinc oxide is added to indium oxide may be used. Indium oxide containing tungsten oxide and zinc oxide (IWZO) can also be formed by sputtering using a target containing 0.5 to 5 wt% tungsten oxide and 0.1 to 1 wt% zinc oxide relative to indium oxide. Other 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 nitrides of metal materials (for example, titanium nitride). A layer of these laminated materials may also be used as the anode. For example, a film laminated in the order of Al, Ti, and ITSO on Ti is preferable because it has a good reflectance, is highly efficient, and can achieve high resolution of several thousand ppi. Alternatively, graphene can also be used as a material used for the anode. In addition, by using a composite material capable of forming the hole injection layer 111 described later as a layer in contact with the anode (typically a hole injection layer), it becomes possible to select an electrode material regardless of the work function.

[0084] The hole injection layer 111 is provided in contact with the anode and has a function of facilitating the injection of holes into the EL layer 103. The hole injection layer 111 can be formed of a phthalocyanine-based compound or complex compound such as phthalocyanine (abbreviation: HPc) or copper phthalocyanine (abbreviation: CuPc), an aromatic amine compound such as 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB) or 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) / (polystyrenesulfonic acid) (abbreviation: PEDOT / PSS).

[0085] The hole injection layer 111 may be formed of a substance having electron acceptor properties. As the substance having acceptor properties, an organic compound having an electron-withdrawing group (such as a halogen group or a cyano group) can be used, and examples of the substance include 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (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-1,3,4,5,6,8,9,10-octafluoro-7H-pyren-2-ylidene)malononitrile, and the like. In particular, compounds in which an electron-withdrawing group is bonded to a condensed aromatic ring having multiple heteroatoms, such as HAT-CN, are thermally stable and preferred. Radialene derivatives having an electron-withdrawing group (especially a halogen group such as a fluoro group, a cyano group, etc.) [3] are preferred because they have a very high electron-accepting property, and specific examples include α,α',α''-1,2,3-cyclopropane triylidene tris[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], and α,α',α''-1,2,3-cyclopropane triylidene tris[2,3,4,5,6-pentafluorobenzeneacetonitrile]. As the substance having acceptor properties, 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.

[0086] In addition, the hole-injecting layer 111 is preferably formed using a composite material containing the above-mentioned material having an acceptor property and an organic compound having a hole-transporting property.

[0087] As the organic compound having a hole transporting property used in the composite material, various organic compounds such as aromatic amine compounds, heteroaromatic compounds, aromatic hydrocarbons, and polymer compounds (oligomers, dendrimers, polymers, etc.) can be used. Note that the organic compound having a hole transporting property used in the composite material is preferably 1×10 -6 cm 2 It is preferable that the organic compound has a hole mobility of 1000 nm or more / Vs. 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-rich heteroaromatic ring. As the condensed aromatic hydrocarbon ring, an anthracene ring, a naphthalene ring, etc. are preferable. As the π-electron-rich heteroaromatic ring, a condensed aromatic ring containing at least one of a pyrrole skeleton, a furan skeleton, and a thiophene skeleton in the ring is preferable, and specifically, a carbazole ring, a dibenzothiophene ring, or a ring in which an aromatic ring or a heteroaromatic ring is further condensed to the above rings is preferable.

[0088] Such organic compounds having hole transport properties preferably have any of a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton. In particular, the organic compounds may be aromatic amines having a substituent containing a dibenzofuran ring or a dibenzothiophene ring, aromatic monoamines having a naphthalene ring, or aromatic monoamines in which a 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group. It is preferable that the organic compounds having hole transport properties are substances having an N,N-bis(4-biphenyl)amino group, because this allows the manufacture of a light-emitting device with a long life.

[0089] Specific examples of organic compounds having hole transport properties as described above include 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)benzylamine (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-(dibenzothiophene-4-yl)phenyl]-4-amino-p-terphenyl ]-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: BBAαNβ NB-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] 4,4′-diphenyl-4′′-[4′-(carbazol-9-yl)biphenyl-4-yl]triphenylamine (abbreviation: YGTBi1BP), 4′-[4-(3-phenyl-9H-carbazol-9-yl)furan-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)furan-4′′-phenyltriphenylamine (abbreviation: TPBiAβNBi), 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-fluorene]-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-carbazol-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-fluorene-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, etc. can be mentioned.

[0090] In addition, as a material having hole transport properties, other aromatic amine compounds such as 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), and 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B) can also be used.

[0091] By forming the hole injection layer 111, the hole injection property is improved, and a light emitting device with a low driving voltage can be obtained.

[0092] Among substances having acceptor properties, organic compounds having acceptor properties are easy to use because they can be easily evaporated and formed into a film.

[0093] The material used for the hole injection layer 111 may be the first compound.

[0094] The hole transport layer 112 is formed by including an organic compound having a hole transport property. -6 cm 2 It is preferable that the hole mobility is 1 / Vs or more.

[0095] Examples of the material having the hole transport property 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-fluorene]-2-yl)-N,N'-diphenyl-4,4'-diaminobiphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluorene-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: PCBANB), Compounds with aromatic amine skeletons such as 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), and N-phenyl-N-[4-(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)benzene, bazolyl)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'-(triphenylen-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(triphenylene-2 4,4′,4″-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,4′,4′′-(phenyl ...Examples of the compounds include compounds having a thiophene skeleton such as 8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III) and 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and compounds having a furan skeleton such as 4,4′,4″-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II). Among the above, 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 reducing the driving voltage. Note that the substances exemplified as the materials having hole transport properties used for the composite material of the hole injection layer 111 can also be suitably used as the material for forming the hole transport layer 112.

[0096] The light-emitting layer 113 in the light-emitting device of one embodiment of the present invention contains a phosphorescent light-emitting substance, a first organic compound, and a second organic compound as described above. 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. When the light-emitting device of one embodiment of the present invention has two or more light-emitting layers in the EL layer 103, for example, a tandem light-emitting device, one of the two light-emitting layers may not have the structure of embodiment 1. 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. The light-emitting layer 113 may contain other materials at the same time. The light-emitting layer 113 may be a stack of two layers with different compositions.

[0097] The luminescent material may be a fluorescent material, a phosphorescent material, a material exhibiting thermally activated delayed fluorescence (TADF), or any other luminescent material.

[0098] Examples of materials that can be used as the fluorescent substance in the light-emitting layer 113 include the following: In addition, fluorescent substances other than these can also be used.

[0099] 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)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), 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-phenylanthracen-2-amine (abbreviation: 2YGABPhA), N,N,9-triphenylanthracen-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-pyrazol-2-yl)-1,1-diphenylquinacridone (abbreviation: DPQd), DCM1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (DCM2), N,N,N′,N′-tetrakis(4-methylphenyl)tetracene-5,11-diamine (p-mPhTD), 7,14-diphenyl-N,N,N′,N′-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviation Name: p-mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-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]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB),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]quinolizin-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), etc. In particular, condensed aromatic diamine compounds such as 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.

[0100] In addition, 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]anthracene-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]phenaza Borin-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 Condensed heteroaromatic compounds containing nitrogen and boron, such as 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]phenazaborine-7,13-diamine (abbreviation: ν-DABNA) and 2-(4-tert-butylphenyl)benz[5,6]indolo[3,2,1-jk]benzo[b]carbazole (abbreviation: tBuPBibc), in particular compounds having a diaza-boranaphtho-anthracene skeleton, can be preferably used because they have a narrow emission spectrum and can emit blue light with good color purity.

[0101] 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]phenazaborine (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 can be preferably used.

[0102] When a phosphorescent substance is used as the light-emitting substance in the light-emitting layer 113, examples of materials that can be used include the following.

[0103] Organometallic iridium compounds with a 4H-triazole skeleton, such as 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]) and tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Mptz)3]). complexes, organometallic iridium complexes with 1H-triazole skeletons such as 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]), 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] organometallic iridium complexes with an imidazole skeleton, such as tris[(6-tert-butyl-3-phenyl-2H-imidazo[4,5-b]pyrazin-1-yl-κC2)phenyl-κC]iridium(III) (abbreviation: [Ir(cb)3]), and organometallic complexes with 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(CF3ppy)2(pic)]), bis[2-(4′,6′-difluorophenyl)pyridinato-N,C 2′ ] Organometallic iridium complexes with phenylpyridine derivatives having electron-withdrawing groups as ligands, such as iridium(III) acetylacetonate (abbreviated as FIracac), are examples of such compounds that exhibit blue phosphorescence and have a peak emission wavelength in the range of 450 nm to 520 nm.

[0104] As the phosphorescent substance, it is possible to use the substances described in Embodiment Mode 1. Note that an organometallic iridium complex having a pyrimidine skeleton is particularly preferable because it has remarkably excellent reliability or luminous efficiency.

[0105] In addition, organometallic iridium complexes having a pyrimidine skeleton, such as (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)]), and bis[4,6-di(naphthalen-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(d1npm)2(dpm)]); Organometallic iridium complexes with a pyrazine skeleton, such as (acetylacetonato)bis(2,3,5-triphenylpyrazinate)iridium(III) (abbreviation: [Ir(tppr)2(acac)]), bis(2,3,5-triphenylpyrazinate)(dipivaloylmethanato)iridium(III) (abbreviation: [Ir(tppr)2(dpm)]), and (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-phenylisoquinolinato-N,C 2′Organometallic iridium compounds with pyridine skeletons such as (3,7-diethyl-4,6-nonanedionato-κO4,κO6)bis[2,4-dimethyl-6-[7-(1-methylethyl)-1-isoquinolinyl-κN]phenyl-κC]iridium(III) and (3,7-diethyl-4,6-nonanedionato-κO4,κO6)bis[2,4-dimethyl-6-[5-(1-methylethyl)-2-quinolinyl-κN]phenyl-κC]iridium(III). In addition to iridium complexes, platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum(II) (abbreviation: PtOEP), tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III) (abbreviation: [Eu(DBM)3(Phen)]), tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III) (abbreviation: [Eu(TTA)3(Phen)]) are examples of rare earth metal complexes. These are compounds that exhibit red phosphorescence and have a peak emission in the wavelength range from 600 nm to 700 nm. In addition, organometallic iridium complexes with a pyrazine skeleton can emit red light with good chromaticity.

[0106] In addition to the above-mentioned phosphorescent compounds, known phosphorescent compounds may be selected and used.

[0107] TADF materials include fullerene and its derivatives, acridine and its derivatives, eosin derivatives, etc. Also included are metal-containing porphyrins including magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), palladium (Pd), etc. Examples of the metal-containing porphyrin include protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF2(OEP)), etioporphyrin-tin fluoride complex (SnF2(Etio I)), and octaethylporphyrin-platinum chloride complex (PtCl2OEP), which are shown in the following structural formulas.

[0108] [ka]

[0109] 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-acridin-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[acridin-9,9′-anthracene]-10′-one (abbreviation: ACRSA), and other heterocyclic compounds having one or both of a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring can also be used. The heterocyclic compound has a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring, and therefore has high electron transport and hole transport properties, and is therefore preferred. Among the skeletons having a π-electron deficient heteroaromatic ring, the pyridine skeleton, the diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), and the triazine skeleton are preferred because they are stable and have good reliability. In particular, the benzofuropyrimidine skeleton, the benzothienopyrimidine skeleton, the benzofuropyrazine skeleton, and the benzothienopyrazine skeleton are preferred because they have high acceptor properties and good reliability. In addition, among the skeletons having a π-electron rich heteroaromatic ring, the acridine skeleton, the phenoxazine skeleton, the phenothiazine skeleton, the furan skeleton, the thiophene skeleton, and the pyrrole skeleton are preferred because they are stable and have good reliability, and therefore, at least one of these skeletons is preferred. Note that the dibenzofuran skeleton is preferred as the furan skeleton, and the dibenzothiophene skeleton is preferred as the thiophene skeleton.In addition, as the pyrrole skeleton, an indole skeleton, a carbazole skeleton, an indolocarbazole skeleton, a bicarbazole skeleton, and a 3-(9-phenyl-9H-carbazole-3-yl)-9H-carbazole skeleton are particularly preferred. In addition, a substance in which a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded is particularly preferred because the electron donating property of the π-electron-rich heteroaromatic ring and the electron accepting property of the π-electron-deficient heteroaromatic ring are both strong, and the energy difference between the S1 level and the T1 level is small, so that thermally activated delayed fluorescence can be efficiently obtained. In addition, an aromatic ring to which an electron-withdrawing group such as a cyano group is bonded may be used instead of the π-electron-deficient heteroaromatic ring. In addition, an aromatic amine skeleton, a phenazine skeleton, or the like can be used as the π-electron-rich skeleton. In addition, examples of the π-electron-deficient skeleton that can be used include 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 or boranthrene, an aromatic ring having a nitrile group or a cyano group such as benzonitrile or cyanobenzene, a heteroaromatic ring, a carbonyl skeleton such as benzophenone, a phosphine oxide skeleton, a sulfone skeleton, etc. In this way, a π-electron-deficient skeleton and a π-electron-rich skeleton can be used in place of at least one of a π-electron-deficient heteroaromatic ring and a π-electron-rich heteroaromatic ring.

[0110] [ka]

[0111] TADF materials are materials that have a small difference between the S1 and T1 levels and have the function of converting triplet excitation energy to singlet excitation energy by reverse intersystem crossing. Therefore, triplet excitation energy can be upconverted to singlet excitation energy by a small amount of thermal energy (reverse intersystem crossing), and singlet excitation states can be generated efficiently. In addition, triplet excitation energy can be converted into light emission.

[0112] In addition, exciplexes (also called exciplexes), which form an excited state with two types of substances, have an extremely small difference between the S1 level and the T1 level and function as TADF materials that can convert triplet excitation energy into singlet excitation energy.

[0113] As an index of the T1 level, a phosphorescence spectrum observed at low temperatures (for example, 77 K to 10 K) may be used. For a TADF material, when a tangent is drawn at the base of the short wavelength side of the fluorescence spectrum, and the energy of the wavelength of the extrapolated line is taken as the S1 level, and a tangent is drawn at the base of the short wavelength side of the phosphorescence spectrum, and the energy of the wavelength of the extrapolated line is taken as the T1 level, the difference between S1 and T1 is preferably 0.3 eV or less, and more preferably 0.2 eV or less.

[0114] In addition, when a TADF material is used as a light-emitting material, the S1 level of the host material is preferably higher than the S1 level of the TADF material, and the T1 level of the host material is preferably higher than the T1 level of the TADF material.

[0115] As the host material of the light-emitting layer, various carrier transporting materials such as a material having an electron transporting property and / or a material having a hole transporting property, or the above-mentioned TADF material can be used.

[0116] As the material having hole transport properties, an organic compound having an amine skeleton, a π-electron-rich heteroaromatic ring skeleton, etc. is preferable. As the π-electron-rich heteroaromatic ring, a condensed 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 in the ring is preferable, and specifically, a carbazole ring, a dibenzothiophene ring, or a ring in which an aromatic ring or a heteroaromatic ring is further condensed to the above is preferable.

[0117] Such organic compounds having hole transport properties preferably have any of a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton. In particular, the organic compounds may be aromatic amines having a substituent containing a dibenzofuran ring or a dibenzothiophene ring, aromatic monoamines having a naphthalene ring, or aromatic monoamines in which a 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group. It is preferable that the organic compounds having hole transport properties are substances having an N,N-bis(4-biphenyl)amino group, because this allows the manufacture of a light-emitting device with a long life.

[0118] 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 (abbreviated as mBPAFLP), 4-phenyl-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBA1BP), 4,4′-diphenyl-4′′-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBBi1BP), 4-(1-naphthyl)-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PC Aromatic amines such as 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), and N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF) Compounds with a carbazole skeleton, such as 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), and 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,Examples of the compounds include compounds having a thiophene skeleton such as 8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III) and 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and compounds having a furan skeleton such as 4,4′,4″-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II). Among the above, 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 reducing the driving voltage. In addition, the organic compounds listed as examples of materials having hole transportability in the hole transport layer can also be used.

[0119] Materials with electron transport properties have an electron mobility of 1×10 at a square root of an electric field strength [V / cm] of 600. -7 cm 2 / Vs or more, preferably 1×10 -6 cm 2 A substance having an electron mobility of 1 / Vs or more is preferable. Note that other substances can be used as long as they have a higher electron transporting property than a hole transporting property.

[0120] Examples of materials having electron transport properties include metal complexes such as bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq2), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (abbreviation: BAlq), bis(8-quinolinolato)zinc(II) (abbreviation: Znq), bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO), and bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ), and organic compounds having a π-electron-deficient heteroaromatic ring. 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, organic compounds containing a heteroaromatic ring having a diazine skeleton, and organic compounds containing a heteroaromatic ring having a triazine skeleton.

[0121] Among them, 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 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 reducing the driving voltage. In addition, benzofuropyrimidine skeleton, benzothienopyrimidine skeleton, benzofuropyrazine skeleton, and benzothienopyrazine skeleton are preferable because of their high acceptor properties and good reliability.

[0122] 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]benzene (abbreviation: OXD-8), and 1,2,4-diphenyl-2-phenyl-1,2,4-triazole (abbreviation: OXD-9). Organic compounds with an azole skeleton, such as 3,5-bis[3-(9H-diazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 2,2′,2″-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), and 4,4′-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOs), H-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,Organic compounds containing heteroaromatic rings with a pyridine skeleton, such as 2-[3-(dibenzothiophene-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3-(3′-dibenzothiophene-4-yl)biphenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3′-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4′-(9-phenanthroline) (abbreviation: PPhen2BP), 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: 4,6mD BTP2Pm-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 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-4mDBt PBfpm), 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)quinazolin-2-yl]-7H-dibenzo[c,g]carbazole (abbreviation: PC-cgDBCzQz), organic compounds with a diazine skeleton such as 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-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 mFBPTzn), 5-[3-(4,6-diphenyl-1,3,5-triazin-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), , 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-dibenzofuranyl}-1,3,Examples of such organic compounds include organic compounds containing a heteroaromatic ring having a triazine skeleton, such as 5-triazine (abbreviation: mBP-TPDBfTzn). In addition, 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 preferred because of their high 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 reducing the driving voltage.

[0123] As a TADF material that can be used as a host material, the same TADF materials listed above can be used. When a TADF material is used as a host material, the triplet excitation energy generated in the TADF material is converted to singlet excitation energy by reverse intersystem crossing, and the energy is then transferred to the light-emitting material, thereby increasing the light-emitting efficiency of the light-emitting device. In this case, the TADF material functions as an energy donor, and the light-emitting material functions as an energy acceptor.

[0124] This is very effective when the luminescent material is a fluorescent luminescent material. In this case, in order to obtain high luminous efficiency, the S1 level of the TADF material is preferably higher than the S1 level of the fluorescent luminescent material. In addition, the T1 level of the TADF material is preferably higher than the S1 level of the fluorescent luminescent material. Therefore, the T1 level of the TADF material is preferably higher than the T1 level of the fluorescent luminescent material.

[0125] It is also preferable to use a TADF material that emits light that overlaps with the wavelength of the lowest energy absorption band of the fluorescent material, because this allows for smooth transfer of excitation energy from the TADF material to the fluorescent material, resulting in efficient emission.

[0126] In addition, 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. In addition, it is preferable that the triplet excitation energy generated in the TADF material does not transfer to the triplet excitation energy of the fluorescent material. For this purpose, it is preferable that the fluorescent material has a protective group around the luminophore (skeleton causing light emission) of the fluorescent material. As the protective group, a substituent having no π bond is preferable, and a saturated hydrocarbon is preferable, specifically, an alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 10 carbon atoms are mentioned, and it is more preferable that there are a plurality of protective groups. Since a substituent having no π bond has poor function of transporting carriers, the distance between the TADF material and the luminophore of the fluorescent material can be increased without affecting carrier transport or carrier recombination. Here, the luminophore refers to an atomic group (skeleton) causing light emission in the fluorescent material. The luminophore preferably has a skeleton having a π bond, preferably contains an aromatic ring, and preferably has a condensed aromatic ring or a condensed heteroaromatic ring. Examples of the condensed aromatic ring or the condensed heteroaromatic ring include a phenanthrene skeleton, a stilbene skeleton, an acridone skeleton, a phenoxazine skeleton, and a phenothiazine skeleton. In particular, fluorescent substances having a naphthalene skeleton, an anthracene skeleton, a fluorene skeleton, a chrysene skeleton, a triphenylene skeleton, a tetracene skeleton, a pyrene skeleton, a perylene skeleton, a coumarin skeleton, a quinacridone skeleton, or a naphthobisbenzofuran skeleton are preferred because they have a high fluorescence quantum yield.

[0127] When a fluorescent emitting material is used as the emitting material, a material having an anthracene skeleton is suitable as the host material. When a material having an anthracene skeleton is used as the host material of the fluorescent emitting material, it is possible to realize an emitting layer having both good luminous efficiency and durability. As a material having an anthracene skeleton to be used as the host material, a material having a diphenylanthracene skeleton, particularly a 9,10-diphenylanthracene skeleton, is preferable because it is chemically stable. In addition, when the host material has a carbazole skeleton, it is preferable because the injection and transport properties of holes are improved, but when the host material contains a benzocarbazole skeleton in which a benzene ring is further condensed to carbazole, the HOMO is shallower by about 0.1 eV than that of carbazole, making it easier for holes to enter, which is more preferable. In particular, when the host material contains a dibenzocarbazole skeleton, it is preferable because the HOMO is shallower by about 0.1 eV than that of carbazole, making it easier for holes to enter, and it also has excellent hole transport properties and high heat resistance. Therefore, a more preferable host material is a substance having both a 9,10-diphenylanthracene skeleton and a carbazole skeleton (or a benzocarbazole skeleton or a dibenzocarbazole skeleton). From the viewpoint of the hole injection / transport property, 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′- 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 Zo[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), etc. In particular, CzPA, cgDBCzPA, 2mBnfPPA, and PCzPA are preferred choices because they show very good properties.

[0128] The host material may be a mixture of a plurality of substances, and when a mixture of host materials is used, it is preferable to mix a material having an electron transporting property with a material having a hole transporting property. By mixing a material having an electron transporting property with 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 be easily controlled. The weight ratio of the content of the material having a hole transporting property to the material having an electron transporting property may be 1:19 to 19:1 (material having a hole transporting property:material having an electron transporting property).

[0129] A phosphorescent material can be used as a part of the mixed material. The phosphorescent material can be used as an energy donor that provides excitation energy to a fluorescent material when the fluorescent material is used as a light-emitting material.

[0130] In addition, these mixed materials may form an exciplex. It is preferable to select a combination that forms an exciplex that emits light that overlaps with the wavelength of the lowest energy absorption band of the light-emitting material, because this makes energy transfer smooth and allows efficient light emission. In addition, the use of this structure is preferable because the driving voltage is reduced.

[0131] At least one of the materials forming the exciplex may be a phosphorescent material, which allows the triplet excitation energy to be efficiently converted into singlet excitation energy by reverse intersystem crossing.

[0132] As a combination of materials that efficiently form an exciplex, it is preferable that the HOMO level of the material having hole transport properties is equal to or higher than the HOMO level of the material having electron transport properties. It is also preferable that the LUMO level of the material having hole transport properties is equal to or higher than the LUMO level of the material having electron transport properties. 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.

[0133] The formation of an exciplex can be confirmed, for example, by comparing the emission spectrum of a material having hole transport properties, the emission spectrum of a material having electron transport properties, and the emission spectrum of a mixed film obtained by mixing these materials, and observing the phenomenon that the emission spectrum of the mixed film shifts to a longer wavelength than the emission spectrum of each material (or has a new peak on the longer wavelength side). Alternatively, the formation of an exciplex can be confirmed by comparing the transient photoluminescence (PL) of a material having hole transport properties, the transient PL of a material having electron transport properties, and the transient PL of a mixed film obtained by mixing these materials, and observing the difference in transient response, such as the transient PL lifetime of the mixed film having a longer lifetime component than the transient PL lifetime of each material, or the proportion of delayed components becoming larger. The above-mentioned transient PL may also be read as transient electroluminescence (EL). That is, the formation of an exciplex can also be confirmed by comparing the transient EL of a material having hole transport properties, the transient EL of a material having electron transport properties, and the transient EL of a mixed film obtained by mixing these materials, and observing the difference in transient response.

[0134] The electron transport layer 114 is formed as a layer containing a substance having an electron transport property. The material having an electron transport property is a material having an electron mobility of 1×10 -7 cm 2 / Vs or more, preferably 1×10 -6 cm 2 A substance having an electron mobility of 100 / Vs or more is preferable. Note that, other substances can be used as long as they have a higher transportability of electrons than holes. Note that, as the organic compound, an organic compound having a π-electron-deficient heteroaromatic ring is preferable. As the organic compound having a π-electron-deficient heteroaromatic ring, for example, it is preferable to use one or more of an organic compound having a heteroaromatic ring with a polyazole skeleton, an organic compound having a heteroaromatic ring with a pyridine skeleton, an organic compound having a heteroaromatic ring with a diazine skeleton, and an organic compound having a heteroaromatic ring with a triazine skeleton.

[0135] As the organic compound having electron transport properties that can be used in the electron transport layer 114, the organic compound that can be used as the organic compound having electron transport properties in the light emitting layer 113 can be used in the same way. Among them, 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 they have 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 reducing the driving voltage. Among them, organic compounds having a phenanthroline skeleton such as mTpPPhen, PnNPhen, and mPPhen2P are preferable, and organic compounds having a phenanthroline dimer structure such as mPPhen2P are more preferable because they have excellent stability.

[0136] The electron transport layer 114 may have a laminated structure. A layer in the electron transport layer 114 having a laminated structure that is in contact with the light-emitting layer 113 may function as a hole blocking layer. When the electron transport layer in contact with the light-emitting layer is made to function as a hole blocking layer, it is preferable to use a material whose HOMO level is deeper than the HOMO level of the material contained in the light-emitting layer 113 by 0.5 eV or more.

[0137] As the electron injection layer 115, a layer containing an alkali metal or alkaline earth metal, such as lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF2), or 8-hydroxyquinolinato-lithium (abbreviation: Liq), or a layer containing 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 or alkaline earth metal, or a compound thereof, or an electride. As the electride, for example, a substance in which electrons are added at a high concentration to a mixed oxide of calcium and aluminum, or the like may be used.

[0138] Note that a layer containing a fluoride of the alkali metal or alkaline earth metal in a substance having an electron transporting property (preferably an organic compound having a bipyridine skeleton) at a concentration at which the fluoride is in a microcrystalline state or higher (50 wt % or higher) can be used as the electron injection layer 115. Since this layer has a low refractive index, it is possible to provide a light-emitting device with better external quantum efficiency.

[0139] The electron-injecting layer 115 may use any of the above substances alone, or may contain any of the above substances in a layer made of a substance having an electron-transporting property.

[0140] Alternatively, 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 capable of injecting holes into a layer in contact with the cathode side of the layer and electrons into a layer in contact with the anode side of the layer by applying a potential. The charge generation layer 116 includes at least a P-type layer 117. The P-type layer 117 is preferably formed using the composite material listed above as a material capable of forming the hole injection layer 111. The P-type layer 117 may also be formed by laminating a film containing an acceptor material and a film containing a hole transport material, both of which are materials that constitute 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, and the light-emitting device operates.

[0141] It is preferable that the charge generating layer 116 is provided with either or both of an electron relay layer 118 and an N-type layer 119 in addition to the P-type layer 117 .

[0142] The electron relay layer 118 contains at least a substance having electron transport properties, 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 having electron transport properties contained in the electron relay layer 118 is preferably between the LUMO level of the acceptor substance in the P-type layer 117 and the LUMO level of the substance contained in the layer in contact with the charge generation layer 116 in the electron transport layer 114. The specific energy level of the LUMO level of the substance having electron transport properties used in the electron relay layer 118 is -5.0 eV or more, preferably -5.0 eV or more and -3.0 eV or less. Note that the substance having electron transport properties used in the electron relay layer 118 is preferably a phthalocyanine-based material or a metal complex having a metal-oxygen bond and an aromatic ligand.

[0143] The N-type layer 119 can be made of a material with high electron injection properties, such as an alkali metal, an alkaline earth metal, a rare earth metal, or a compound thereof (alkali metal compounds (including oxides such as lithium oxide, halides, and carbonates such as lithium carbonate and cesium carbonate), alkaline earth metal compounds (including oxides, halides, and carbonates), or rare earth metal compounds (including oxides, halides, and carbonates)).

[0144] In addition, when the N-type layer 119 is formed containing a substance having an electron transporting property and a donor substance, as the donor substance, an alkali metal, an alkaline earth metal, a rare earth metal, or a compound thereof (an alkali metal compound (including an oxide such as lithium oxide, a halide, or a carbonate such as lithium carbonate or cesium carbonate), an alkaline earth metal compound (including an oxide, a halide, or a carbonate), or a rare earth metal compound (including an oxide, a halide, or a carbonate)), or an organic compound such as tetrathianaphthacene (abbreviation: TTN), nickelocene, or decamethylnickelocene can be used. Note that as the substance having an electron transporting property, a material similar to the material constituting the electron transporting layer 114 described above can be used.

[0145] The second electrode 102 is an electrode including a cathode. The second electrode 102 may have a laminated structure, in which case a layer in contact with the EL layer 103 functions as the cathode. As a material for forming the cathode, a metal, an alloy, an electrically conductive compound, a mixture thereof, or the like having a small work function (specifically, 3.8 eV or less) can be used. Specific examples of such a cathode material include alkali metals such as lithium (Li) or cesium (Cs), elements belonging to Group 1 or Group 2 of the periodic table such as magnesium (Mg), calcium (Ca), and strontium (Sr), and alloys (MgAg, AlLi) and compounds (lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF2), etc.) containing these, rare earth metals such as europium (Eu), ytterbium (Yb), and alloys containing these, etc. 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, various conductive materials such as Al, Ag, ITO, indium oxide-tin oxide containing silicon or silicon oxide can be used as the cathode regardless of the magnitude of the work function.

[0146] When the second electrode 102 is formed using a material that is transparent to visible light, a light-emitting device that emits light from the second electrode 102 side can be obtained.

[0147] These conductive materials can be formed into a film by a dry method such as a vacuum deposition method or a sputtering method, an inkjet method, a spin coating method, etc. Also, they 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.

[0148] In addition, various methods, whether dry or wet, can be used to form the EL layer 103. 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.

[0149] Moreover, the above-mentioned electrodes or layers may be formed using different film formation methods.

[0150] Next, an embodiment of a light-emitting device having a structure in which a plurality of light-emitting units are stacked (also called 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 a structure almost similar to that of the EL layer 103 shown in FIG. 1(A). In other words, it can be said that the organic EL element shown in FIG. 1(C) is an organic EL element having a plurality of light-emitting units, and the organic EL elements shown in FIG. 1(A) and FIG. 1(B) are light-emitting devices having one light-emitting unit.

[0151] In Fig. 1(C), 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, and a charge generation layer 513 is provided between the first light-emitting unit 511 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 as those described in the description of Fig. 1(A) can be applied to them. In addition, the first light-emitting unit 511 and the second light-emitting unit 512 may have the same structure or different structures.

[0152] 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 between the first electrode 501 and the second electrode 502. That is, in FIG. 1C, when a voltage is applied so that the potential of the anode is higher than the potential of the cathode, the charge generation layer 513 may inject electrons into the first light-emitting unit 511 and inject holes into the second light-emitting unit 512.

[0153] The charge generation layer 513 is preferably formed to have the same structure as the charge generation layer 116 described in FIG. 1B. The composite material of an organic compound and a metal oxide used in the P-type layer has excellent carrier injection and carrier transport properties, and therefore can realize low-voltage driving and low-current driving. 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, so that the light-emitting unit does not need to be provided with a hole injection layer.

[0154] It is also preferable to provide an N-type layer 119 in the charge generation layer 513. 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 light-emitting unit on the anode side, and therefore it is not necessarily necessary to form an electron injection layer in the light-emitting unit on the anode side (here, the first light-emitting unit 511).

[0155] 1C, a light-emitting device having two light-emitting units has been described, but the present invention can be applied to a light-emitting device having three or more light-emitting units stacked in the same manner. By disposing a plurality of light-emitting units between a pair of electrodes and separating them with a charge generation layer 513 as in the light-emitting device according to this embodiment, it is possible to realize a device that can emit high-luminance light while keeping the current density low and has a long life. In addition, it is possible to realize a light-emitting device that can be driven at a low voltage and consumes low power.

[0156] In addition, by making the emission colors of the respective light-emitting units different, it is possible to obtain light emission of a desired color from the light-emitting device as a whole. For example, in a light-emitting device having two light-emitting units, it is possible to obtain a light-emitting device that emits white light by obtaining red and green emission colors from the first light-emitting unit and blue emission color from the second light-emitting unit.

[0157] In addition, each layer and electrode such as the above-mentioned EL layer 103, the first light-emitting unit 511, the second light-emitting unit 512, and the charge generation layer can be formed by using, for example, a deposition method (including a vacuum deposition method), a droplet discharge method (also called an ink-jet method), a coating method, a gravure printing method, etc. In addition, they may contain a low molecular weight material, a medium molecular weight material (including an oligomer and a dendrimer), or a polymer material.

[0158] (Embodiment 2) In this embodiment, a display device using the light-emitting device described in Embodiment 1 will be described.

[0159] In this embodiment, a display device manufactured using the light-emitting device described in Embodiment 1 will be described with reference to FIG. 2. FIG. 2(A) is a top view showing the display device, and FIG. 2(B) is a cross-sectional view taken along the lines AB and CD in FIG. 2(A). This display device includes a driver circuit section (source line driver circuit) 601, a pixel section 602, and a driver circuit section (gate line driver circuit) 603, all of which are shown by dotted lines, for controlling light emission from the light-emitting device. Reference numeral 604 denotes a sealing substrate, 605 denotes a sealant, and the inside surrounded by the sealant 605 defines a space 607.

[0160] The lead wiring 608 is wiring for transmitting signals input to the source line driver circuit 601 and the gate line driver circuit 603, and receives a video signal, a clock signal, a start signal, a reset signal, and the like from an FPC (flexible printed circuit) 609 serving as an external input terminal. Although only an FPC is shown here, a printed wiring board (PWB) may be attached to this FPC. In this specification, the display device includes not only the display device itself, but also a state in which an FPC or PWB is attached to it.

[0161] Next, the cross-sectional structure will be described with reference to Fig. 2(B). A driver circuit portion and a pixel portion are formed on an element substrate 610, and here, a source line driver circuit 601 which is the driver circuit portion and one pixel in the pixel portion 602 are shown.

[0162] The element substrate 610 may be made of a substrate made of glass, quartz, organic resin, metal, alloy, semiconductor, or a plastic substrate made of FRP (Fiber Reinforced Plastics), PVF (Polyvinyl fluoride), polyester, acrylic resin, or the like.

[0163] The structure of the transistors used in the pixels and the driver circuits is not particularly limited. For example, the transistors may be inverted staggered transistors or staggered transistors. Furthermore, the transistors may be top-gate transistors or bottom-gate transistors. The semiconductor material used in the transistors is not particularly limited, and for example, silicon, germanium, silicon carbide, gallium nitride, or the like may 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.

[0164] The crystallinity of a semiconductor material used for a transistor is not particularly limited, and any of an amorphous semiconductor and a crystalline semiconductor (a microcrystalline semiconductor, a polycrystalline semiconductor, a single crystal semiconductor, or a semiconductor having a crystalline region in a part) may be used. The use of a crystalline semiconductor is preferable because it can suppress deterioration of transistor characteristics.

[0165] Here, in addition to the transistors provided in the pixels and the driver circuits, an oxide semiconductor is preferably used for a semiconductor device such as a transistor used in a touch sensor or the like, which will be described later. In particular, an oxide semiconductor having a wider band gap than silicon is preferably used. By using an oxide semiconductor having a wider band gap than silicon, the current in the off state of the transistor can be reduced.

[0166] The oxide semiconductor preferably contains at least indium (In) or zinc (Zn), and more preferably contains an oxide represented by In-M-Zn oxide (M is a metal such as Al, Ti, Ga, Ge, Y, Zr, Sn, La, Ce, or Hf).

[0167] In particular, it is preferable to use, as the semiconductor layer, an oxide semiconductor film which has a plurality of crystal parts whose c-axes are oriented perpendicular to a surface on which the semiconductor layer is formed or a top surface of the semiconductor layer and which has no grain boundaries between adjacent crystal parts.

[0168] By using such a material for the semiconductor layer, fluctuations in electrical characteristics are suppressed, and a highly reliable transistor can be realized.

[0169] In addition, the transistor having the above-mentioned semiconductor layer can hold charge accumulated in a capacitance through the transistor for a long period of time due to its low off-state current. By applying such a transistor to a pixel, it is possible to stop a driver circuit while maintaining the gray level of an image displayed in each display region. As a result, an electronic device with extremely low power consumption can be realized.

[0170] It is preferable to provide an undercoat film in order to stabilize the characteristics of the transistor. The undercoat film can be prepared as a single layer or a multilayer structure using an inorganic insulating film such as a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a silicon nitride oxide film. The undercoat film can be formed by a sputtering method, a CVD (Chemical Vapor Deposition) method (such as a plasma CVD method, a thermal CVD method, or a MOCVD (Metal Organic CVD) method), an ALD (Atomic Layer Deposition) method, a coating method, a printing method, or the like. Note that the undercoat film need not be provided if it is not necessary.

[0171] The FET 623 indicates one of the transistors formed in the driving circuit 601. The driving circuit may be formed of various CMOS circuits, PMOS circuits, or NMOS circuits. In this embodiment, a driver-integrated type in which a driving circuit is formed on a substrate is shown, but this is not necessarily required, and the driving circuit may be formed externally instead of on the substrate.

[0172] In addition, the pixel portion 602 is formed by a plurality of pixels including a switching FET 611, a current control FET 612, and a first electrode 613 electrically connected to the drain of the FET 612. However, the present invention is not limited to this, and the pixel portion may be formed by combining three or more FETs and a capacitive element.

[0173] An insulator 614 is formed to cover an end portion of the first electrode 613. Here, the insulator 614 can be formed by using a positive type photosensitive acrylic resin film.

[0174] In order to improve the covering ability of an organic compound layer or the like to be formed later, a curved surface having a curvature is formed at the upper end or lower end of the insulator 614. For example, when a positive type photosensitive acrylic resin is used as the material of the insulator 614, it is preferable that only the upper end of the insulator 614 has a curved surface having a radius of curvature (0.2 μm to 3 μm). In addition, either a negative type photosensitive resin or a positive type photosensitive resin can be used as the insulator 614.

[0175] An EL layer 616 and a second electrode 617 are formed on the first electrode 613. Here, it is desirable to use a material with a large work function as a material used for the first electrode 613 that functions as an anode. For example, in addition to 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, or a Pt film, a laminated structure of a titanium nitride film and a film mainly composed of aluminum, or a three-layer structure of a titanium nitride film, a film mainly composed of aluminum, and a titanium nitride film, can be used. Note that a laminated structure provides low resistance as wiring, good ohmic contact, and can further function as an anode.

[0176] The EL layer 616 is formed by various methods such as a deposition method using a deposition mask, an inkjet method, a spin coating method, etc. The EL layer 616 includes the configuration described in the embodiment 1. Other materials constituting the EL layer 616 may be low molecular weight compounds or high molecular weight compounds (including oligomers and dendrimers).

[0177] Furthermore, the second electrode 617 formed on the EL layer 616 and functioning as a cathode is preferably made of a material having a small work function (such as Al, Mg, Li, Ca, or alloys and compounds thereof (MgAg, MgIn, AlLi, etc.)). When light generated in the EL layer 616 is transmitted through the second electrode 617, the second electrode 617 is preferably made of a laminate of a thin metal thin film and a transparent conductive film (such as ITO, indium oxide containing 2 to 20 wt % zinc oxide, indium tin oxide containing silicon, zinc oxide (ZnO), etc.).

[0178] Note that a light-emitting device is formed with 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 a pixel portion is formed with a plurality of light-emitting devices, but the display device in this embodiment may include both the light-emitting device described in Embodiment 1 and light-emitting devices having other structures.

[0179] Furthermore, by bonding the sealing substrate 604 to the element substrate 610 with a sealant 605, a structure is formed 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. The space 607 is filled with a filler, and may be filled with an inert gas (nitrogen, argon, etc.) or a sealant. A recess is formed in the sealing substrate and a desiccant is provided therein to suppress deterioration due to the influence of moisture, which is a preferable configuration.

[0180] It is preferable to use epoxy resin or glass frit for the sealing material 605. It is also preferable that these materials are as moisture and oxygen impermeable as possible. In addition, the sealing substrate 604 may be made of a glass substrate, a quartz substrate, or a plastic substrate made of FRP (Fiber Reinforced Plastics), PVF (Polyvinyl Fluoride), polyester, acrylic resin, or the like.

[0181] 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. The protective film may be formed so as to cover the exposed portion of the sealant 605. The protective film may be provided so as to cover the surfaces and side surfaces of the pair of substrates, the exposed side surfaces of the sealing layer, the insulating layer, etc.

[0182] The protective film can be made of a material that is difficult for impurities such as water to permeate, and therefore can effectively prevent impurities such as water from diffusing from the outside to the inside.

[0183] Examples of materials that can be used to form the protective film include oxides, nitrides, fluorides, sulfides, ternary compounds, metals, and polymers. For example, materials containing aluminum oxide, hafnium oxide, hafnium silicate, lanthanum oxide, silicon oxide, 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, materials containing aluminum nitride, hafnium nitride, silicon nitride, tantalum nitride, titanium nitride, niobium nitride, molybdenum nitride, zirconium nitride, or gallium nitride, materials 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, and oxides containing yttrium and zirconium can be used.

[0184] The protective film is preferably formed using a film formation method with good step coverage. One such method is the atomic layer deposition (ALD) method. It is preferable to use a material that can be formed using the ALD method for the protective film. By using the ALD method, it is possible to form a dense protective film with reduced defects such as cracks and pinholes, or with a uniform thickness. In addition, damage to the processed member when the protective film is formed can be reduced.

[0185] For example, by forming a protective film using the ALD method, it is possible to form a uniform protective film with few defects on surfaces having complex uneven shapes, as well as on the top, side and back surfaces of a touch panel.

[0186] In this manner, a display device manufactured using the light-emitting device described in Embodiment 1 can be obtained.

[0187] The display device in this embodiment uses the light-emitting device described in Embodiment 1, and therefore a display device with good characteristics can be obtained. Specifically, since the light-emitting device described in Embodiment 1 has high emission efficiency, a display device with low power consumption can be obtained. In addition, since the light-emitting device described in Embodiment 1 has good reliability, a display device with good reliability can be obtained.

[0188] This embodiment mode can be freely combined with other embodiment modes.

[0189] (Embodiment 3) 3A and 3B, a display device is formed by forming a plurality of light-emitting devices 130 over an insulating layer 175. In this embodiment, a display device according to another embodiment of the present invention will be described in detail.

[0190] The display device 100 includes a pixel section 177 in which a plurality of pixels 178 are arranged in a matrix. The pixel 178 includes a sub-pixel 110R, a sub-pixel 110G, and a sub-pixel 110B.

[0191] In this specification and the like, when describing matters common to, for example, the subpixels 110R, 110G, and 110B, they may be referred to as subpixels 110. When describing matters common to other components distinguished by alphabets, they may be described using symbols without the alphabets.

[0192] The sub-pixel 110R emits red light, the sub-pixel 110G emits green light, and the sub-pixel 110B emits blue light. This allows an image to be displayed in the pixel section 177. In the present embodiment, sub-pixels of three colors, red (R), green (G), and blue (B), are described as an example, but combinations of sub-pixels of other colors may be used. The number of sub-pixels is not limited to three, and may be four or more. Examples of the four sub-pixels include sub-pixels of four colors, R, G, B, and white (W), sub-pixels of four colors, R, G, B, and yellow (Y), and sub-pixels of R, G, B, and infrared (IR).

[0193] In this specification and the like, the row direction may be referred to as the X direction, and the column direction may be referred to as the Y direction. The X direction and the Y direction intersect, for example, perpendicularly.

[0194] 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.

[0195] A connection section 140 is provided outside the pixel section 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. Also, the connection section 140 is provided with a conductive layer 151C.

[0196] 3A shows an example in which the region 141 and the connection portion 140 are located on the right side of the pixel portion 177, but the positions of the region 141 and the connection portion 140 are not particularly limited. The region 141 and the connection portion 140 may be singular or plural.

[0197] Fig. 3(B) is an example of a cross-sectional view between dashed line A1-A2 in Fig. 3(A). As shown in Fig. 3(B), the display device 100 has an insulating layer 171, a conductive layer 172 on the insulating layer 171, an insulating layer 173 on the insulating layer 171 and on the conductive layer 172, an insulating layer 174 on the insulating layer 173, and an insulating layer 175 on the insulating layer 174. The insulating layer 171 is provided on a substrate (not shown). An opening reaching the conductive layer 172 is provided in the insulating layer 175, the insulating layer 174, and the insulating layer 173, and a plug 176 is provided to fill the opening.

[0198] In the pixel section 177, the light emitting device 130 is provided on the insulating layer 175 and the plug 176. A protective layer 131 is provided so as to cover the light emitting device 130. The substrate 120 is bonded onto the protective layer 131 by a resin layer 122. In addition, an inorganic insulating layer 125 and an insulating layer 127 on the inorganic insulating layer 125 are preferably provided between adjacent light emitting devices 130.

[0199] 3B shows multiple cross sections of the inorganic insulating layer 125 and the insulating layer 127, it is preferable that the inorganic insulating layer 125 and the insulating layer 127 are connected to one another when the display device 100 is viewed from above. In other words, it is preferable that the inorganic insulating layer 125 and the insulating layer 127 are insulating layers having openings over the first electrodes.

[0200] In FIG. 3B, the light emitting device 130 includes a light emitting device 130R, a light emitting device 130G, and a light emitting device 130B. The light emitting device 130R, the light emitting device 130G, and the light emitting device 130B emit light of different colors. For example, the light emitting device 130R can emit red light, the light emitting device 130G can emit green light, and the light emitting device 130B can emit blue light. The light emitting device 130R, the light emitting device 130G, or the light emitting device 130B may emit other visible light or infrared light.

[0201] The display device of one embodiment of the present invention can be, for example, a top emission type that emits light in a direction opposite to a substrate on which a light-emitting device is formed. Note that the display device of one embodiment of the present invention may be a bottom emission type.

[0202] The light-emitting device 130R has 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 second electrode (common electrode) 102 on the common layer 104. The common layer 104 may or may not be provided, but is preferably provided because it can reduce damage to the EL layer 103R during processing. When the common layer 104 is provided, it is preferable that the common layer 104 is an electron injection layer.

[0203] The light-emitting layer in the light-emitting device 130G has the configuration shown in the first embodiment, and includes a first electrode (pixel electrode) consisting of a conductive layer 151G and a conductive layer 152G, an EL layer 103G on the first electrode, a common layer 104 on the EL layer 103G, and a second electrode (common electrode) 102 on the common layer 104. The common layer 104 may or may not be provided, but is preferably provided because it can reduce damage to the EL layer 103G during processing. When the common layer 104 is provided, it is preferable that the common layer 104 is an electron injection layer. When the common layer 104 is provided, the laminated structure of the EL layer 103G and the common layer 104 corresponds to the EL layer 103 in the first embodiment.

[0204] The light-emitting device 130B has 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 second electrode (common electrode) 102 on the common layer 104. The common layer 104 may or may not be provided, but is preferably provided because it can reduce damage to the EL layer 103B during processing. When the common layer 104 is provided, it is preferable that the common layer 104 is an electron injection layer.

[0205] One of the pixel electrode and the common electrode of the light-emitting device 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.

[0206] The EL layer 103R, the EL layer 103G, and the EL layer 103B are independent in an island shape, either individually or for each luminescent color. By providing the EL layer 103 in an island shape for each light-emitting device 130, it is possible to suppress leakage current between adjacent light-emitting devices 130 even in a high-definition display device. This makes it possible to prevent crosstalk and realize a display device with extremely high contrast. In particular, it is possible to realize a display device with high current efficiency at low luminance.

[0207] The island-shaped EL layer 103 is formed by depositing an EL film and processing the EL film by using a photolithography method.

[0208] The EL layer 103 is preferably provided so as to cover the upper surface 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. In addition, by covering the side surfaces 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 prevented, and therefore short-circuiting of the light-emitting device 130 can be prevented.

[0209] 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.

[0210] For example, a metal material can be used as the conductive layer 151. Specifically, metals such as 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.

[0211] The conductive layer 152 can be made of an oxide containing one or more selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon. For example, it is preferable to use a conductive oxide containing one or more of 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, and indium zinc oxide containing silicon. 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 for the conductive layer 152.

[0212] The conductive layer 151 may have a stacked structure of multiple layers having different materials, and the conductive layer 152 may have a stacked structure of multiple layers having different materials. In this case, the conductive layer 151 may have a layer using a material that can be used for the conductive layer 152, such as a conductive oxide, or the conductive layer 152 may have a layer using a material that can be used for the conductive layer 151, such as a metal material. 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.

[0213] Note that the conductive layer 151 preferably has a tapered end. Specifically, the conductive layer 151 preferably has a tapered end 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 end. By making the side surface of the conductive layer 152 tapered, the coverage of the EL layer 103 provided along the side surface of the conductive layer 152 can be improved.

[0214] Next, an example of a method for manufacturing the display device 100 having the structure shown in FIG. 4A will be described with reference to FIGS.

[0215] [Production method example 1] The thin films (insulating films, semiconductor films, conductive films, etc.) that constitute the display device can be formed using a sputtering method, a chemical vapor deposition (CVD) method, a vacuum deposition method, a pulsed laser deposition (PLD) method, an ALD method, or the like.

[0216] Furthermore, the thin films (insulating films, semiconductor films, conductive films, etc.) constituting the display device can be formed by wet film formation methods such as spin coating, dipping, spray coating, inkjet, dispensing, screen printing, offset printing, doctor knife method, slit coating, roll coating, curtain coating, or knife coating.

[0217] Furthermore, when processing the thin films that constitute the display device, they can be processed using, for example, a photolithography method.

[0218] In the photolithography method, the light used for exposure may 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 light, KrF laser light, ArF laser light, etc. may also be used. Exposure may also be performed by immersion exposure technology. Extreme ultraviolet (EUV) light or X-rays may also be used as the light used for exposure. An electron beam may also be used instead of the light used for exposure.

[0219] The thin film can be etched by dry etching, wet etching, sandblasting, or the like.

[0220] 4(A), an insulating layer 171 is formed on a substrate (not shown). Then, a conductive layer 172 and a conductive layer 179 are formed on the insulating layer 171, and an insulating layer 173 is formed on the insulating layer 171 so as to cover the conductive layer 172 and the conductive layer 179. Then, an insulating layer 174 is formed on the insulating layer 173, and an insulating layer 175 is formed on the insulating layer 174.

[0221] The substrate may be a substrate having at least a heat resistance sufficient to withstand a subsequent heat treatment, such as a glass substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, an organic resin substrate, a single crystal semiconductor substrate made of silicon, silicon carbide, or the like, a polycrystalline semiconductor substrate, a compound semiconductor substrate made of silicon germanium, or the like, or an SOI substrate.

[0222] Then, an opening is formed in the insulating layer 175, the insulating layer 174, and the insulating layer 173, reaching the conductive layer 172. Then, a plug 176 is formed to fill the opening.

[0223] Subsequently, a conductive film 151f, which will later become the conductive layers 151R, 151G, 151B, and 151C, is formed on the plugs 176 and the insulating layer 175. The conductive film 151f may be made of, for example, a metal material.

[0224] Subsequently, a resist mask 191 is formed over the conductive film 151cf. The resist mask 191 can be formed by applying a photosensitive material (photoresist) and performing exposure and development.

[0225] 4B, for example, the conductive film 151f is removed from a region that does not overlap with the resist mask 191. As a result, the conductive layer 151 is formed.

[0226] 4(C), the resist mask 191 is removed. The resist mask 191 can be removed by ashing using oxygen plasma, for example.

[0227] Next, as shown in FIG. 4(D), an insulating film 156f, which will later become insulating layers 156R, 156G, 156B, and 156C, is formed on conductive layer 151R, conductive layer 151G, conductive layer 151B, conductive layer 151C, and insulating layer 175.

[0228] The insulating film 156f can be an inorganic insulating film such as an insulating oxide film, a nitride insulating film, an oxynitride insulating film, or a nitride oxide insulating film, for example, a silicon oxynitride film.

[0229] Subsequently, as shown in FIG. 4(E), 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.

[0230] 5A, a conductive film 152f is formed over 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, 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 a stacked film.

[0231] 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.

[0232] 5(C), the EL film 103Rf is formed on the conductive layer 152R, the conductive layer 152G, the conductive layer 152B, and the insulating layer 175. Note that, as shown in FIG. 5(C), the EL film 103Rf is not formed on the conductive layer 152C.

[0233] Subsequently, as shown in FIG. 5(C), a sacrificial film 158f and a mask film 159Rf are formed.

[0234] By providing the sacrificial film 158Rf on the EL film 103Rf, damage to the EL film 103Rf during the manufacturing process of the display device can be reduced, and the reliability of the light-emitting device can be improved.

[0235] The sacrificial film 158Rf is made of 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. The mask film 159Rf is made of a film having a high etching selectivity with respect to the sacrificial film 158Rf.

[0236] The sacrificial film 158Rf and the mask film 159Rf are formed at a temperature lower than the heat-resistant temperature of the EL film 103Rf. The substrate temperature when forming the sacrificial film 158Rf and the mask film 159Rf is typically 200° C. or less, preferably 150° C. or less, more preferably 120° C. or less, more preferably 100° C. or less, and further preferably 80° C. or less.

[0237] It is preferable that the sacrificial film 158Rf and the mask film 159Rf are made of a film that can be removed by a wet etching method.

[0238] The sacrificial film 158Rf formed on and in contact with the EL film 103Rf is preferably formed using a method that causes less damage to the EL film 103Rf than the mask film 159Rf. For example, the ALD method or the vacuum deposition method is more preferable than the sputtering method.

[0239] The sacrificial film 158Rf and the mask film 159Rf may each be made of one or more of a metal film, an alloy film, a metal oxide film, a semiconductor film, an organic insulating film, and an inorganic insulating film, for example.

[0240] The sacrificial film 158Rf and the mask film 159Rf may be made of, for example, a metal material such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, or tantalum, or an alloy material containing the metal material. 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 ultraviolet rays to the EL film 103Rf can be suppressed, and deterioration of the EL film 103Rf can be suppressed, which is preferable.

[0241] Furthermore, for the sacrificial film 158Rf and the mask film 159Rf, metal oxides such as In-Ga-Zn oxide, indium oxide, In-Zn oxide, In-Sn oxide, indium titanium oxide (In-Ti oxide), indium 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), and indium tin oxide containing silicon can be used.

[0242] In addition, in the above metal oxide, an element M (M is one or more elements selected from aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium) may be used instead of gallium.

[0243] For 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 a high affinity with the semiconductor manufacturing process, or a compound containing the above semiconductor material may be used.

[0244] 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.

[0245] 5(C), a resist mask 190R is formed. The resist mask 190R can be formed by applying a photosensitive material (photoresist) and then performing exposure and development.

[0246] The resist mask 190R is provided in a position overlapping with the conductive layer 152R. The resist mask 190R is preferably provided also in a position overlapping with the conductive layer 152C, which can prevent the conductive layer 152C from being damaged during the manufacturing process of the display device.

[0247] 5(D), a resist mask 190R is used to remove a portion of the mask film 159Rf to form a mask layer 159R. The mask layer 159R remains on the conductive layer 152R and the conductive layer 152C. The resist mask 190R is then removed. The mask layer 159R is used as a mask (also called a hard mask) to remove a portion of the sacrificial film 158Rf to form a sacrificial layer 158R.

[0248] By using the wet etching method, damage to the EL film 103Rf during processing of the sacrificial film 158Rf and the mask film 159Rf can be reduced compared to the case of using the dry etching method. When using the wet etching method, it is preferable to use a chemical solution using, for example, a developer, a tetramethylammonium hydroxide solution (TMAH), dilute hydrofluoric acid, oxalic acid, phosphoric acid, acetic acid, nitric acid, or a mixture of these.

[0249] Furthermore, when dry etching is used in processing the sacrificial film 158Rf, deterioration of the EL film 103Rf can be suppressed by not using an oxygen-containing gas as an etching gas.

[0250] The resist mask 190R can be removed in the same manner as the resist mask 191.

[0251] 5(D), the EL film 103Rf is processed to form the EL layer 103R. For example, the mask layer 159R and the sacrificial layer 158R are used as a hard mask to remove a part of the EL film 103Rf to form the EL layer 103R.

[0252] 5D, a laminated structure of the EL layer 103R, the sacrificial layer 158R, and the mask layer 159R remains on the conductive layer 152R. Also, the conductive layers 152G and 152B are exposed.

[0253] The EL film 103Rf is preferably processed by anisotropic etching, particularly anisotropic dry etching, or wet etching may be used.

[0254] When dry etching is used, deterioration of the EL film 103Rf can be suppressed by not using an oxygen-containing gas as an etching gas.

[0255] Moreover, 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 sufficiently high etching speed. This makes it possible to suppress damage to the EL film 103Rf. Furthermore, problems such as adhesion of reaction products generated during etching can be suppressed.

[0256] When using a dry etching method, it is preferable to use a gas containing one or more of H2, CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, or a group 18 element such as He or Ar as an etching gas. Alternatively, it is preferable to use a gas containing one or more of these elements and oxygen as an etching gas. Alternatively, oxygen gas may be used as an etching gas.

[0257] Next, as shown in FIG. 6(A), an EL film 103Gf that will later become the EL layer 103G is formed.

[0258] The EL film 103Gf can be formed by the same method as that used to form the EL film 103Rf, and can have the same configuration as the EL film 103Rf.

[0259] Next, a sacrificial film 158Gf and a mask film 159Gf are formed in this order. Then, a resist mask 190G is formed at a position overlapping the conductive layer 152G. The material and forming method of the sacrificial film 158Gf and the mask film 159Gf are the same as those applicable to the sacrificial film 158Rf and the mask film 159Rf. The material and forming method of the resist mask 190G are the same as those applicable to the resist mask 190R.

[0260] 6(B), a resist mask 190G is used to remove a portion of the mask film 159Gf to form a mask layer 159G. The mask layer 159G remains on the conductive layer 152G. The resist mask 190G is then removed. The mask layer 159G is then used as a mask to remove a portion of the sacrificial film 158Gf to form a sacrificial layer 158G. The EL film 103Gf is then processed to form the EL layer 103G.

[0261] 6(C), the EL film 103Bf is formed. The EL film 103Bf can be formed by the same method as that used for forming the EL film 103Rf. The EL film 103Bf can have the same structure as the EL film 103Rf.

[0262] 6(C), a sacrificial film 158Bf and a mask film 159Bf are formed in this order. Then, a resist mask 190B is formed at a position overlapping the conductive layer 152B. The material and forming method of the sacrificial film 158Bf and the mask film 159Bf are the same as those applicable to the sacrificial film 158Rf and the mask film 159Rf. The material and forming method of the resist mask 190B are the same as those applicable to the resist mask 190R.

[0263] 6(D), a resist mask 190B is used to remove a portion of the mask film 159Bf to form a mask layer 159B. The mask layer 159B remains on the conductive layer 152B. The resist mask 190B is then removed. The mask layer 159B is then used as a mask to remove a portion of the sacrificial film 158Bf to form a sacrificial layer 158B. The EL film 103Bf is then processed to form the EL layer 103B. For example, the mask layer 159B and the sacrificial layer 158B are used as a hard mask to remove a portion of the EL film 103Bf to form the EL layer 103B.

[0264] As a result, a laminated structure of the EL layer 103B, the sacrificial layer 158B, and the mask layer 159B remains on the conductive layer 152B. Also, the mask layers 159R and 159G are exposed.

[0265] It is preferable that the side surfaces of the EL layer 103R, the EL layer 103G, and the EL layer 103B are perpendicular or approximately perpendicular to the surface on which they are formed. For example, it is preferable that the angle between the surface on which they are formed and these side surfaces is 60 degrees or more and 90 degrees or less.

[0266] As described above, the distance between two adjacent ones of the EL layer 103R, the EL layer 103G, and the EL layer 103B formed by the photolithography method can be narrowed to 8 μm or less, 5 μm or less, 3 μm or less, 2 μm or less, or 1 μm or less. Here, the distance can be defined, for example, as the distance between two adjacent opposing ends of the EL layer 103R, the EL layer 103G, and the EL layer 103B. In this way, by narrowing the distance between the island-shaped organic compound layers, a display device having high definition and a large aperture ratio can be provided. In addition, 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.

[0267] Subsequently, as shown in FIG. 7(A), it is preferable to remove the mask layers 159R, 159G, and 159B.

[0268] The mask layer removal process can be performed using the same method as the mask layer processing process. In particular, by using a wet etching method, damage to the EL layer 103 during removal of the mask layer can be reduced compared to the case of using a dry etching method.

[0269] The mask layer may also be removed by dissolving it in a solvent such as water or alcohol, such as ethyl alcohol, methyl alcohol, isopropyl alcohol (IPA), or glycerin.

[0270] After removing the mask layer, a drying treatment may be performed to remove water adsorbed on the surface. For example, a heat treatment can be performed in an inert gas atmosphere or a reduced pressure atmosphere. The heat treatment can be performed at a substrate temperature of 50° C. to 200° C., preferably 60° C. to 150° C., and more preferably 70° C. to 120° C. A reduced pressure atmosphere is preferable because it allows drying at a lower temperature.

[0271] Subsequently, as shown in FIG. 7(B), an inorganic insulating film 125f is formed.

[0272] Subsequently, as shown in FIG. 7(C), an insulating film 127f, which will later become the insulating layer 127, is formed on the inorganic insulating film 125f.

[0273] The substrate temperature when forming the inorganic insulating film 125f and the insulating film 127f is preferably 60°C or more, 80°C or more, 100°C or more, or 120°C or more, and 200°C or less, 180°C or less, 160°C or less, 150°C or less, or 140°C or less.

[0274] As the inorganic insulating film 125f, it is preferable to form 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 within the above substrate temperature range.

[0275] The inorganic insulating film 125f is preferably formed by, for example, the ALD method. By using the ALD method, damage during film formation can be reduced, and a film with high coverage can be formed, which is preferable. As the inorganic insulating film 125f, for example, an aluminum oxide film is preferably formed by the ALD method.

[0276] The insulating film 127f is preferably formed by using the above-mentioned wet film formation method. The insulating film 127f is preferably formed by using a photosensitive material, for example, by spin coating, and more specifically, is preferably formed by using a photosensitive resin composition containing an acrylic resin.

[0277] Subsequently, exposure is performed to expose a part 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 layers 152R, 152G, and 152B, and around the conductive layer 152C.

[0278] The width of the insulating layer 127 to be formed later can be controlled by the exposed region of the insulating film 127f. In this embodiment, the insulating layer 127 is processed so as to have a portion overlapping with the upper surface of the conductive layer 151.

[0279] The light used for exposure preferably contains i-line (wavelength 365 nm), and may contain at least one of g-line (wavelength 436 nm) and h-line (wavelength 405 nm).

[0280] Subsequently, as shown in FIG. 8(A), development is performed to remove the exposed area of ​​the insulating film 127f, thereby forming an insulating layer 127a.

[0281] 8(B), an etching process is performed using the insulating layer 127a as a mask to remove a part of the inorganic insulating film 125f and to thin the thickness of the sacrificial layers 158R, 158G, and 158B. As a result, the inorganic insulating layer 125 is formed under the insulating layer 127a. In addition, the surfaces of the thin parts of the sacrificial layers 158R, 158G, and 158B are exposed. In the following, the etching process using the insulating layer 127a as a mask may be referred to as the first etching process.

[0282] The first etching process can be performed by dry etching or wet etching. Note that, when the inorganic insulating film 125f is formed using the same material as the sacrificial layers 158R, 158G, and 158B, the first etching process can be performed at once, which is preferable.

[0283] When dry etching is performed, it is preferable to use a chlorine-based gas. As the chlorine-based gas, Cl2, BCl3, SiCl4, CCl4, etc. can be used alone or in a mixture of two or more gases. In addition, oxygen gas, hydrogen gas, helium gas, argon gas, etc. can be appropriately added alone or in a mixture of two or more gases to the chlorine-based gas. By using dry etching, the thin film regions of the sacrificial layer 158R, the sacrificial layer 158G, and the sacrificial layer 158B can be formed with good in-plane uniformity.

[0284] 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.

[0285] In addition, the first etching process is preferably performed by wet etching. By using the wet etching method, damage to the EL layer 103R, the EL layer 103G, and the EL layer 103B can be reduced compared to the case of using the dry etching method. For example, the wet etching can be performed by using an alkaline solution or an acid solution.

[0286] In the first etching process, it is preferable to stop the etching process when the film thickness becomes thin without completely removing the sacrificial layers 158R, 158G, and 158B. In this way, by leaving the corresponding sacrificial layers 158R, 158G, and 158B on the EL layers 103R, 103G, and 103B, it is possible to prevent the EL layers 103R, 103G, and 103B from being damaged in the processing of the subsequent steps.

[0287] Next, the entire substrate is exposed to light, and it is preferable to irradiate the insulating layer 127a with visible light or ultraviolet light. The energy density of the exposure is 0 mJ / cm 2 Larger, 800mJ / cm 2 It is preferable to set the concentration to 0 mJ / cm or less. 2 Larger than 500mJ / cm 2 It is more preferable to set the following. By performing such exposure after development, the transparency of the insulating layer 127a can be improved in some cases. In addition, the substrate temperature required for a heat treatment for transforming the insulating layer 127a into a tapered shape in a later step can be reduced in some cases.

[0288] Here, the presence of a barrier insulating layer against oxygen (e.g., an aluminum oxide film or the like) as the sacrificial layers 158R, 158G, and 158B can reduce the diffusion of oxygen into the EL layers 103R, 103G, and 103B.

[0289] Next, a heat treatment (also referred to as post-baking) is performed. By performing the heat treatment, the insulating layer 127a can be transformed into the insulating layer 127 having a tapered shape on the side surface (FIG. 8C). The heat treatment is performed at a temperature lower than the heat resistance temperature of the organic compound layer. The heat treatment can be performed at a substrate temperature of 50° C. to 200° C., preferably 60° C. to 150° C., more preferably 70° C. to 130° C. The heating atmosphere may be an air atmosphere or an inert gas atmosphere. The heating atmosphere may be an atmospheric pressure atmosphere or a reduced pressure atmosphere. This can improve the adhesion between the insulating layer 127 and the inorganic insulating layer 125 and also improve the corrosion resistance of the insulating layer 127.

[0290] In the first etching process, the sacrificial layers 158R, 158G, and 158B are not completely removed, and the sacrificial layers 158R, 158G, and 158B are left in a state where their thicknesses are reduced, thereby preventing the EL layers 103R, 103G, and 103B from being damaged and deteriorated in the heat treatment, thereby improving the reliability of the light-emitting device.

[0291] 9(A), an etching process is performed using the insulating layer 127 as a mask to remove parts of the sacrificial layers 158R, 158G, and 158B. As a result, openings are formed in the sacrificial layers 158R, 158G, and 158B, respectively, and the upper surfaces of the EL layers 103R, 103G, 103B, and the conductive layer 152C are exposed. Note that, hereinafter, this etching process may be referred to as a second etching process.

[0292] An end portion of the inorganic insulating layer 125 is covered with an insulating layer 127. Also, Fig. 9(A) shows an example in which a part of the end portion of the sacrificial layer 158G (specifically, the tapered portion formed by the first etching process) is covered with the insulating layer 127, and the tapered portion formed by the second etching process is exposed.

[0293] The second etching process is performed by wet etching. By using the wet etching method, damage to the EL layer 103R, the EL layer 103G, and the EL layer 103B can be reduced compared to the case of using the dry etching method. The wet etching can be performed by using, for example, an alkaline solution or an acidic solution.

[0294] 9(B), 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 deposition method.

[0295] 9C, the protective layer 131 is formed on the common electrode 155. The protective layer 131 can be formed by a method such as a vacuum deposition method, a sputtering method, a CVD method, or an ALD method.

[0296] Then, the substrate 120 is attached over the protective layer 131 using the resin layer 122, so that a display device can be manufactured. As described above, in a manufacturing method of a display device according to one embodiment of the present invention, the insulating layer 156 is provided so as to have a region overlapping with a side surface of the conductive layer 151, and the conductive layer 152 is formed so as to cover the conductive layer 151 and the insulating layer 156. This can increase the yield of the display device and suppress the occurrence of defects.

[0297] As described above, in the manufacturing method of the display device in the present embodiment, the island-shaped EL layer 103R, the island-shaped EL layer 103G, and the EL layer 103B are formed by forming a film on one surface and then processing it by a photolithography method, rather than using a fine metal mask, so that the island-shaped layers can be formed with a uniform thickness. In addition, a high-definition display device or a display device with a high aperture ratio can be realized. In addition, even if the definition or aperture ratio is high and the distance between the subpixels is extremely short, the EL layer 103R, the EL layer 103G, and the EL layer 103B can be prevented from contacting each other in adjacent subpixels. Therefore, it is possible to prevent leakage current from occurring between the subpixels. This makes it possible to prevent crosstalk and realize a display device with extremely high contrast. In addition, even if the display device has a tandem-type light-emitting device manufactured by using a photolithography method, a display device with good characteristics can be provided.

[0298] (Embodiment 4) In this embodiment, a display device according to one embodiment of the present invention will be described.

[0299] The display device of the present embodiment can be a high-definition display device. Therefore, the display device of the present embodiment can be used for, for example, a display unit of a wristwatch-type or bracelet-type information terminal (wearable device), a VR device such as a head-mounted display (HMD), and a head-mounted wearable device such as a glasses-type AR device.

[0300] The display device of the present embodiment can be a high-resolution display device or a large-sized display device. Therefore, the display device of the present embodiment can be used in electronic devices having relatively large screens, such as television devices, desktop or notebook personal computers, computer monitors, digital signage, and large game machines such as pachinko machines, as well as in the display units of digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, personal digital assistants, and sound reproducing devices.

[0301] [Display module] 10A shows a perspective view of a 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 of display devices 100B to 100E described later.

[0302] The display module 280 has a substrate 291 and a substrate 292. The display module 280 has a display unit 281. The display unit 281 is a region that displays an image in the display module 280, and is a region where light from each pixel provided in a pixel unit 284 described later can be viewed.

[0303] 10B is a perspective view showing a schematic configuration of the substrate 291 side. A circuit portion 282, a pixel circuit portion 283 on the circuit portion 282, and a pixel portion 284 on the pixel circuit portion 283 are laminated on the substrate 291. A terminal portion 285 for connecting to an FPC 290 is provided in a portion of the substrate 291 that does not overlap with the pixel portion 284. The terminal portion 285 and the circuit portion 282 are electrically connected by a wiring portion 286 composed of a plurality of wirings.

[0304] The pixel section 284 has 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 above embodiments can be applied to the pixel 284a.

[0305] The pixel circuit section 283 has a plurality of pixel circuits 283a that are periodically arranged.

[0306] One pixel circuit 283a is a circuit that controls the driving of a plurality of elements included in one pixel 284a.

[0307] The circuit portion 282 includes a circuit for driving each pixel circuit 283a of the pixel circuit portion 283. For example, it is preferable that the circuit portion 282 includes one or both of a gate line driver circuit and a source line driver circuit. In addition, the circuit portion 282 may include at least one of an arithmetic circuit, a memory circuit, a power supply circuit, and the like.

[0308] The FPC 290 functions as wiring for supplying a video signal, a power supply potential, or the like from the outside to the circuit portion 282. In addition, an IC may be mounted on the FPC 290.

[0309] Since the display module 280 can be configured such that one or both of the pixel circuit portion 283 and the circuit portion 282 are stacked below the pixel portion 284, the aperture ratio (effective display area ratio) of the display portion 281 can be made extremely high.

[0310] Such a display module 280 has extremely high resolution and can be suitably used in VR devices such as HMDs or glasses-type AR devices. For example, even in a configuration in which the display unit of the display module 280 is viewed through a lens, the display module 280 has an extremely high resolution display unit 281, so that pixels are not visible even when the display unit is enlarged with a lens, and a highly immersive display can be performed. In addition, the display module 280 is not limited to this and can be suitably used in electronic devices having a relatively small display unit.

[0311] [Display device 100A] A display device 100A shown 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.

[0312] The substrate 301 corresponds to the substrate 291 in FIGS. 10A and 10B. The transistor 310 is a transistor having a channel formation region in the substrate 301. For example, a semiconductor substrate such as a single crystal silicon substrate can be used as the substrate 301. The transistor 310 includes a part of the 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 drain. The insulating layer 314 is provided to cover a side surface of the conductive layer 311.

[0313] In addition, an element isolation layer 315 is provided between two adjacent transistors 310 so as to be embedded in the substrate 301 .

[0314] In addition, an insulating layer 261 is provided to cover the transistor 310 , and a capacitor 240 is provided on the insulating layer 261 .

[0315] Capacitor 240 has conductive layer 241, conductive layer 245, and insulating layer 243 located therebetween. Conductive layer 241 functions as one electrode of capacitor 240, conductive layer 245 functions as the other electrode of capacitor 240, and insulating layer 243 functions as a dielectric of capacitor 240.

[0316] The conductive layer 241 is provided over the insulating layer 261 and is embedded in the insulating layer 254. The conductive layer 241 is electrically connected to one of the source and the drain of the transistor 310 by a plug 271 embedded in the insulating layer 261. The 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.

[0317] An insulating layer 255 is provided covering 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. Light-emitting device 130R, light-emitting device 130G, and light-emitting device 130B are provided on the insulating layer 175. An insulator is provided in the region between adjacent light-emitting devices.

[0318] An insulating layer 156R is provided so as to have an area overlapping with a side surface of the conductive layer 151R, an insulating layer 156G is provided so as to have an area overlapping with a side surface of the conductive layer 151G, and an insulating layer 156B is provided so as to have an area overlapping with a side surface of the conductive layer 151B. A conductive layer 152R is provided so as to cover the conductive layer 151R and the insulating layer 156R, a conductive layer 152G is provided so as to cover the conductive layer 151G and the insulating layer 156G, and a conductive layer 152B is provided so as to cover the conductive layer 151B and the insulating layer 156B. 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.

[0319] The conductive layer 151R, the conductive layer 151G, and the conductive layer 151B are electrically connected to one of the source or the drain of the transistor 310 via 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 a plug 271 embedded in the insulating layer 261. Various conductive materials can be used for the plug.

[0320] Further, a protective layer 131 is provided on the light emitting devices 130R, 130G, and 130B. The substrate 120 is bonded onto the protective layer 131 with a resin layer 122. For details of the components from the light emitting devices 130 to the substrate 120, refer to the second embodiment. The substrate 120 corresponds to the substrate 292 in FIG. 10(A).

[0321] Fig. 11(B) is a modified example of the display device 100A shown in Fig. 11(A). The display device shown in Fig. 11(B) has a colored layer 132R, a colored layer 132G, and a colored layer 132B, and the light-emitting device 130 has an area overlapping one of the colored layer 132R, the colored layer 132G, and the colored layer 132B. In the display device shown in Fig. 11(B), the light-emitting device 130 can emit, for example, white light. Also, 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.

[0322] [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.

[0323] 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 dashed line.

[0324] The display device 100B has a pixel unit 177, a connection unit 140, a circuit 356, wiring 355, etc. 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 having the display device 100B, an IC (integrated circuit), and an FPC. Here, a display device having a connector such as an FPC attached to a substrate, or a display device having an IC mounted on the substrate, is called a display module.

[0325] The connection section 140 is provided outside the pixel section 177. There may be one or more connection sections 140. The connection section 140 electrically connects the common electrode of the light emitting device and the conductive layer, and can supply a potential to the common electrode.

[0326] The circuit 356 can be, for example, a scanning line driver circuit.

[0327] The wiring 355 has a function of supplying signals and power to the pixel portion 177 and the circuit 356. The signals and power are input to the wiring 355 from the outside via the FPC 353 or from the IC 354.

[0328] 12 shows an example in which an IC 354 is provided on a substrate 351 by a chip on glass (COG) method or a chip on film (COF) method. For example, an IC having a scanning line driver circuit or a signal line driver circuit can be used as the IC 354. Note that the display device 100B and the display module may not include an IC. Also, the IC may be mounted on an FPC by a COF method, for example.

[0329] FIG. 13 shows an example of a cross section of the display device 100B, in which a portion of the region including the FPC 353, a portion of the circuit 356, a portion of the pixel portion 177, a portion of the connection portion 140, and a portion of the region including the end portion are cut away.

[0330] [Display device 100C] The display device 100C shown in FIG. 13 has, 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 130B that emits blue light, etc.

[0331] For details of the light emitting devices 130R, 130G, and 130B, refer to the first embodiment.

[0332] Light-emitting device 130R has conductive layer 224R, conductive layer 151R on conductive layer 224R, and conductive layer 152R on conductive layer 151R. Light-emitting device 130G has conductive layer 224G, conductive layer 151G on conductive layer 224G, and conductive layer 152G on conductive layer 151G. Light-emitting device 130B has conductive layer 224B, conductive layer 151B on conductive layer 224B, and conductive layer 152B on conductive layer 151B.

[0333] The conductive layer 224R is connected to the conductive layer 222b of the transistor 205 through an opening provided in the insulating layer 214. An end of the conductive layer 151R is located outside an end of the conductive layer 224R. An insulating layer 156R is provided to have a region in contact with a 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.

[0334] Conductive layer 224G, conductive layer 151G, conductive layer 152G, and insulating layer 156G in light-emitting device 130G, and conductive layer 224B, conductive layer 151B, conductive layer 152B, and insulating layer 156B in light-emitting device 130B are similar to conductive layer 224R, conductive layer 151R, conductive layer 152R, and insulating layer 156R in light-emitting device 130R, and therefore detailed description thereof will be omitted.

[0335] Recesses are formed in the conductive layers 224R, 224G, and 224B so as to cover the openings provided in the insulating layer 214. The layer 128 is embedded in the recesses.

[0336] The layer 128 has a function of planarizing the recesses of 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, which are electrically connected to the conductive layer 224R, the conductive layer 224G, and the conductive layer 224B, are provided on the conductive layer 224R, the conductive layer 224G, and the conductive layer 224B, and the layer 128. Therefore, the regions overlapping with the recesses of the conductive layer 224R, the conductive layer 224G, and the conductive layer 224B can also be used as light-emitting regions, and the aperture ratio of the pixel can be increased.

[0337] The layer 128 may be an insulating layer or a conductive layer. Various inorganic insulating materials, organic insulating materials, and conductive materials can be appropriately used for the layer 128. In particular, the layer 128 is preferably formed using an insulating material, and more preferably formed using an organic insulating material. For example, the organic insulating material that can be used for the insulating layer 127 described above can be used for the layer 128.

[0338] 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 via an adhesive layer 142. The substrate 352 is provided with a light shielding layer 157. A solid sealing structure, a hollow sealing structure, or the like can be applied to seal the light emitting device 130. In FIG. 13, the space between the substrate 352 and the substrate 351 is filled with the adhesive layer 142, and a solid sealing structure is applied. Alternatively, the space may be filled with an inert gas (nitrogen, argon, or the like), and a hollow sealing structure may be applied. In this case, the adhesive layer 142 may be provided so as not to overlap with the light emitting device. The space may also be filled with a resin different from the adhesive layer 142 provided in a frame shape.

[0339] 13 shows an example in which the connection portion 140 has a conductive layer 224C obtained by processing the same conductive film as the conductive layers 224R, 224G, and 224B, a conductive layer 151C obtained by processing the same conductive film as the conductive layers 151R, 151G, and 151B, and a conductive layer 152C obtained by processing the same conductive film as the conductive layers 152R, 152G, and 152B. Also, FIG. 13 shows an example in which an insulating layer 156C is provided so as to have an area overlapping with a side surface of the conductive layer 151C.

[0340] 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.

[0341] An insulating layer 211, an insulating layer 213, an insulating layer 215, and an insulating layer 214 are provided over a substrate 351 in this order. A part of the insulating layer 211 functions as a gate insulating layer for each transistor. A part of the insulating layer 213 functions as a gate insulating layer for each transistor. The insulating layer 215 is provided to cover the transistors. The insulating layer 214 is provided to cover the transistors and functions as a planarizing layer. Note that the number of gate insulating layers and the number of insulating layers covering the transistors are not limited, and each may be a single layer or two or more layers.

[0342] Each of the insulating layers 211, 213, and 215 is preferably an inorganic insulating film.

[0343] The insulating layer 214, which functions as a planarizing layer, is preferably an organic insulating layer.

[0344] The transistor 201 and the transistor 205 each have 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, an insulating layer 213 functioning as a gate insulating layer, and a conductive layer 223 functioning as a gate.

[0345] A connection portion 204 is provided in an area 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 an example of a laminated structure of a conductive film obtained by processing the same conductive film as the conductive layers 224R, 224G, and 224B, a conductive film obtained by processing the same conductive film as the conductive layers 151R, 151G, and 151B, and a conductive film obtained by processing the same conductive film as the conductive layers 152R, 152G, and 152B. On the upper surface of the connection portion 204, the conductive layer 166 is exposed. This allows the connection portion 204 and the FPC 353 to be electrically connected via the connection layer 242.

[0346] It is preferable to provide a light-shielding layer 157 on the surface of the substrate 352 facing the substrate 351. The light-shielding layer 157 can be provided between adjacent light-emitting devices, on the connection portion 140, on the circuit 356, etc. In addition, various optical members can be disposed on the outside of the substrate 352.

[0347] The materials usable for the substrate 120 can be used for the substrate 351 and the substrate 352, respectively.

[0348] The adhesive layer 142 may be made of a material that can be used for the resin layer 122 .

[0349] The connection layer 242 may be an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), or the like.

[0350] [Display device 100D] A display device 100D shown in FIG. 14 differs from the display device 100A shown in FIG. 13 mainly in that the display device 100D is a bottom-emission type display device.

[0351] Light emitted by the light emitting device is emitted to the side of the substrate 351. It is preferable that a material having high transparency to visible light is used for the substrate 351. On the other hand, the light transmissivity of a material used for the substrate 352 does not matter.

[0352] A light-shielding 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 the light-shielding layer 317 is provided over the substrate 351, the insulating layer 153 is provided over the light-shielding layer 317, and the transistors 201, 205, etc. are provided over the insulating layer 153.

[0353] Light emitting device 130R includes a conductive layer 112R, a conductive layer 126R on conductive layer 112R, and a conductive layer 129R on conductive layer 126R.

[0354] Light emitting device 130B has conductive layer 112B, conductive layer 126B on conductive layer 112B, and conductive layer 129B on conductive layer 126B.

[0355] The conductive layers 112R, 112B, 126R, 126B, 129R, and 129B are each made of a material that is highly transparent to visible light. The second electrode 102 is preferably made of a material that reflects visible light.

[0356] Although the light emitting device 130G is not shown in FIG. 14, the light emitting device 130G is also provided.

[0357] In addition, although FIG. 14 and other figures show an example in which the upper surface of layer 128 has a flat portion, the shape of layer 128 is not particularly limited.

[0358] [Display device 100E] The display device 100E shown in FIG. 15 is a modification of the display device 100B shown in FIG. 13, and differs from the display device 100B mainly in that the display device 100E has colored layers 132R, 132G, and 132B.

[0359] In the display device 100E, the light emitting device 130 has an area overlapping 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 facing the substrate 351. An end of the colored layer 132R, an end of the colored layer 132G, and an end of the colored layer 132B can overlap the light blocking layer 157.

[0360] In the display device 100E, the light emitting device 130 can emit, for example, white light. 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. The display device 100E may be configured such that the colored layers 132R, 132G, and 132B are provided between the protective layer 131 and the adhesive layer 142.

[0361] This embodiment mode can be combined with other embodiment modes or examples as appropriate. In addition, in the case where a plurality of configuration examples are shown in one embodiment mode in this specification, the configuration examples can be combined as appropriate.

[0362] (Embodiment 5) In this embodiment, an electronic device according to one embodiment of the present invention will be described.

[0363] The electronic devices of this embodiment include the display device of one embodiment of the present invention in a display portion. The display device of one embodiment of the present invention has low power consumption and high reliability. Therefore, the display device of one embodiment of the present invention can be used in the display portion of various electronic devices.

[0364] Examples of electronic devices include electronic devices with relatively large screens, such as television devices, desktop or notebook personal computers, computer monitors, digital signage, large game machines such as pachinko machines, as well as digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, personal digital assistants, and audio playback devices.

[0365] 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).

[0366] Electronic device 700A shown in FIG. 16(A) and electronic device 700B shown in FIG. 16(B) each have a pair of display panels 751, a pair of housings 721, a communication unit (not shown), a pair of mounting units 723, a control unit (not shown), an imaging unit (not shown), a pair of optical members 753, a frame 757, and a pair of nose pads 758.

[0367] The display device of one embodiment of the present invention can be applied to the display panel 751. Thus, the electronic device can be highly reliable.

[0368] Each of the electronic device 700A and the electronic device 700B can project an image displayed on the display panel 751 onto a display area 756 of the optical member 753. Since the optical member 753 has translucency, a user can see the image displayed in the display area superimposed on a transmitted image visually recognized through the optical member 753.

[0369] 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. In addition, the electronic device 700A and the electronic device 700B may each be provided with an acceleration sensor such as a gyro sensor, thereby detecting the orientation of the user's head and displaying an image corresponding to the orientation in the display area 756.

[0370] The communication unit has a wireless communication device and can supply, for example, a video signal through the wireless communication device. Note that instead of or in addition to the wireless communication device, a connector to which a cable through which a video signal and a power supply potential can be connected may be provided.

[0371] Furthermore, the electronic device 700A and the electronic device 700B are provided with a battery, which can be charged wirelessly and / or wired.

[0372] The housing 721 may be provided with a touch sensor module.

[0373] As the touch sensor module, various touch sensors can be applied. For example, various types of sensors can be adopted, such as a capacitance type, a resistive film type, an infrared type, an electromagnetic induction type, a surface acoustic wave type, or an optical type. In particular, it is preferable to apply a capacitance type or an optical type sensor to the touch sensor module.

[0374] Electronic device 800A shown in FIG. 16(C) and electronic device 800B shown in FIG. 16(D) each have a pair of display units 820, a housing 821, a communication unit 822, a pair of mounting units 823, a control unit 824, a pair of imaging units 825, and a pair of lenses 832.

[0375] The display device of one embodiment of the present invention can be applied to the display portion 820. Thus, the electronic device can be made highly reliable.

[0376] Display unit 820 is provided inside housing 821 at a position that can be viewed through lens 832. Also, by displaying different images on the pair of display units 820, it is possible to perform three-dimensional display using parallax.

[0377] It is preferable that electronic device 800A and electronic device 800B each have a mechanism capable of adjusting the left-right positions of lens 832 and display unit 820 so that they are optimally positioned according to the position of the user's eyes.

[0378] The mounting portion 823 allows the user to mount the electronic device 800A or the electronic device 800B on the head.

[0379] The imaging unit 825 has a function of acquiring external information. 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. In addition, multiple cameras may be provided so as to be compatible with multiple angles of view, such as telephoto and wide angle.

[0380] The electronic device 800A may have a vibration mechanism that functions as a bone conduction earphone.

[0381] The electronic device 800A and the electronic device 800B may each have an input terminal. The input terminal can be connected to 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.

[0382] The electronic device of one embodiment of the present invention may have a function of wireless communication with the earphone 750.

[0383] 16B includes an earphone unit 727. A part of a wiring connecting the earphone unit 727 and a control unit may be disposed inside the housing 721 or the attachment unit 723.

[0384] 16D includes an earphone unit 827. For example, the earphone unit 827 and the control unit 824 may be configured to be connected to each other by wire.

[0385] As described above, as electronic devices according to one embodiment of the present invention, both glasses-type devices (such as the electronic device 700A and the electronic device 700B) and goggles-type devices (such as the electronic device 800A and the electronic device 800B) are suitable.

[0386] An electronic device 6500 shown in FIG. 17A is a portable information terminal that can be used as a smartphone.

[0387] 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, and a light source 6508. The display portion 6502 has a touch panel function.

[0388] The display device of one embodiment of the present invention can be applied to the display portion 6502. Therefore, the electronic device can be highly reliable.

[0389] FIG. 17B is a schematic cross-sectional view including the end portion of the housing 6501 on the microphone 6506 side.

[0390] A light-transmitting protective member 6510 is provided on the display surface side of the housing 6501, and a display panel 6511, optical members 6512, a touch sensor panel 6513, a printed circuit board 6517, a battery 6518, etc. are arranged in the space surrounded by the housing 6501 and the protective member 6510.

[0391] A display panel 6511, an optical member 6512, and a touch sensor panel 6513 are fixed to the protective member 6510 by an adhesive layer (not shown).

[0392] In an area outside the display unit 6502, a part of the display panel 6511 is folded back, and the folded back part is connected to an FPC 6515. An IC 6516 is mounted on the FPC 6515. The FPC 6515 is connected to a terminal provided on a printed circuit board 6517.

[0393] The display device of one embodiment of the present invention can be applied to the display panel 6511. Therefore, an extremely lightweight electronic device can be realized. In addition, since the display panel 6511 is extremely thin, a large-capacity battery 6518 can be mounted thereon while keeping the thickness of the electronic device small. In addition, by folding back a part of the display panel 6511 and arranging a connection portion with the FPC 6515 on the back side of the pixel portion, an electronic device with a narrow frame can be realized.

[0394] 17C shows an example of a television set. In a television set 7100, a display portion 7000 is incorporated in a housing 7171. Here, the housing 7171 is supported by a stand 7173.

[0395] The display device of one embodiment of the present invention can be applied to the display portion 7000. Therefore, the electronic device can be provided with high reliability.

[0396] A television set 7100 shown in FIG. 17C can be operated using an operation switch provided in a housing 7171 and a remote control 7151 provided separately.

[0397] 17D shows an example of a laptop personal computer 7200. The laptop personal computer 7200 includes a housing 7211, a keyboard 7212, a pointing device 7213, and an external connection port 7214. A display portion 7000 is incorporated in the housing 7211.

[0398] The display device of one embodiment of the present invention can be applied to the display portion 7000. Therefore, the electronic device can be provided with high reliability.

[0399] 17(E) and 17(F) show an example of digital signage.

[0400] 17E includes a housing 7301, a display portion 7000, and a speaker 7303. The digital signage 7300 may further include an LED lamp, an operation key (including a power switch or an operation switch), a connection terminal, various sensors, a microphone, and the like.

[0401] 17F shows a digital signage 7400 attached to a cylindrical pillar 7401. The digital signage 7400 has a display unit 7000 provided along the curved surface of the pillar 7401.

[0402] 17E and 17F, the display device of one embodiment of the present invention can be applied to the display portion 7000. Therefore, the electronic device can have high reliability.

[0403] The larger the display unit 7000, the more information can be provided at one time. Also, the larger the display unit 7000, the more easily it catches people's attention, which can increase the advertising effect of, for example, advertisements.

[0404] Furthermore, as shown in FIGS. 17(E) and 17(F), it is preferable that the digital signage 7300 or the digital signage 7400 be capable of linking with an information terminal 7311 or an information terminal 7411 such as a smartphone carried by a user via wireless communication.

[0405] The electronic devices shown in Figures 18(A) to 18(G) have a housing 9000, a display unit 9001, a speaker 9003, operation keys 9005 (including a power switch or an operation switch), a connection terminal 9006, a sensor 9007 (including a function of measuring force, displacement, position, speed, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substances, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor or infrared rays), a microphone 9008, etc.

[0406] 18(A) to 18(G) have various functions, such as a function of displaying various information (still images, videos, text images, etc.) on a display unit, a touch panel function, a function of displaying a calendar, date, time, etc., a function of controlling processing by various software (programs), a wireless communication function, a function of reading and processing a program or data recorded in a recording medium, etc.

[0407] The electronic devices shown in FIGS. 18A to 18G will be described in detail below.

[0408] FIG. 18A is a perspective view showing a mobile information terminal 9171. The mobile information terminal 9171 can be used as, for example, a smartphone. Note that the mobile information terminal 9171 may be provided with a speaker 9003, a connection terminal 9006, a sensor 9007, or the like. The mobile information terminal 9171 can display text and image information on a plurality of surfaces thereof. FIG. 18A shows an example in which three icons 9050 are displayed. Information 9051 shown in a dashed rectangle can also be displayed on another surface of the display unit 9001. Examples of the information 9051 include notification of incoming e-mail, SNS, phone call, etc., the title of the e-mail or SNS, the sender's name, date and time, time, remaining battery level, radio wave intensity, and the like. Alternatively, the icon 9050, etc. may be displayed at the position where the information 9051 is displayed.

[0409] 18(B) is a perspective view of a mobile information terminal 9172. The mobile information terminal 9172 has a function of displaying information on three or more surfaces of the display unit 9001. Here, an example is shown in which information 9052, information 9053, and information 9054 are displayed on different surfaces. For example, a user can check information 9053 displayed in a position that can be observed from above the mobile information terminal 9172 while the mobile information terminal 9172 is stored in a breast pocket of clothes.

[0410] 18C is a perspective view showing a tablet terminal 9173. The tablet terminal 9173 is capable of executing various applications such as mobile phone, e-mail, text browsing and creation, music playback, Internet communication, computer games, etc. The tablet terminal 9173 has a display unit 9001, a camera 9002, a microphone 9008, and a speaker 9003 on the front side of a housing 9000, operation keys 9005 as operation buttons on the left side of the housing 9000, and a connection terminal 9006 on the bottom.

[0411] FIG. 18D is a perspective view showing a wristwatch-type mobile information terminal 9200. The mobile information terminal 9200 can be used as, for example, a smart watch (registered trademark). The display surface of the display unit 9001 is curved, and display can be performed along the curved display surface. The mobile information terminal 9200 can also perform hands-free conversation by communicating with, for example, a headset capable of wireless communication. The mobile information terminal 9200 can also perform data transmission and charging with another information terminal through a connection terminal 9006. Note that charging may be performed by wireless power supply.

[0412] 18(E) to 18(G) are perspective views showing a foldable mobile information terminal 9201. FIG. 18(E) shows the mobile information terminal 9201 in an unfolded state, FIG. 18(G) shows the mobile information terminal 9201 in a folded state, and FIG. 18(F) shows a perspective view of a state in the middle of changing from one of FIG. 18(E) and FIG. 18(G) to the other. The mobile information terminal 9201 has excellent portability in a folded state, and has excellent viewability of a display due to a seamless wide display area in an unfolded state. A display portion 9001 of the mobile information terminal 9201 is supported by three housings 9000 connected by a hinge 9055. For example, the display portion 9001 can be bent with a curvature radius of 0.1 mm to 150 mm.

[0413] This embodiment mode can be combined with other embodiment modes or examples as appropriate. In addition, in the case where a plurality of configuration examples are shown in one embodiment mode in this specification, the configuration examples can be combined as appropriate. EXAMPLES

[0414] Example 1 This example describes detailed manufacturing methods for a light-emitting device 1 which is a light-emitting device of one embodiment of the present invention and a comparative light-emitting device 1 which is a comparative light-emitting device, and also describes measurement results of initial characteristics and reliability thereof.

[0415] The structural formulae of the main compounds used in the present examples are shown below.

[0416] [ka]

[0417] (Method of manufacturing light-emitting device 1) First, 50 nm of titanium (Ti), 70 nm of aluminum (Al), and 6 nm of Ti were laminated on a glass substrate from the substrate side, and then the substrate was baked at 300° C. for 1 hour in air. After that, 10 nm of indium tin oxide containing silicon oxide (ITSO) was formed by sputtering to form a first electrode 101 with a size of 2 mm×2 mm. The ITSO functions as an anode, and is regarded as the first electrode 101 together with the laminated structure of Ti and Al.

[0418] Next, the surface of the substrate was washed with water as a pretreatment for forming a light-emitting device on the substrate.

[0419] After that, about 1 × 10 -4 The substrate was introduced into a vacuum deposition apparatus whose inside had been reduced in pressure to 1 Pa, and vacuum baking was carried out at 170° C. for 60 minutes in a heating chamber of the vacuum deposition apparatus, and then the substrate was allowed to cool for about 30 minutes.

[0420] Next, the substrate was fixed to a holder installed in a vacuum deposition apparatus so that the surface on which the first electrode 101 was formed was facing downward, and N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF) represented by the above structural formula (i) and an electron acceptor material (OCHD-003) containing fluorine and having a molecular weight of 672 were co-deposited by a deposition method to a thickness of 10 nm on the inorganic insulating film and the first electrode 101 in a weight ratio of 1:0.03 (=PCBBiF:OCHD-003) to form a hole injection layer 111.

[0421] On the hole injection layer 111, PCBBiF was evaporated to a thickness of 10 nm to form a hole transport layer 112.

[0422] Subsequently, 8-(1,1':4',1''-terphenyl-3-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm) represented by the above structural formula (ii), 9-(2-naphthyl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: βNCCP) represented by the above structural formula (iii), and [2-d3- The light-emitting layer 113 was formed by co-evaporating 40 nm of methyl-8-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN2)phenyl-κC]iridium(III) (abbreviation: Ir(5mppy-d3)2(mbfpypy-d3)) and βNCCP in a weight ratio of 0.6:0.4:0.1 (=8mpTP-4mDBtPBfpm:βNCCP:Ir(5mppy-d3)2(mbfpypy-d3)).

[0423] After that, 2-{3-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}dibenzo[f,h]quinoxaline (abbreviation: 2mPCCzPDBq) represented by the above structural formula (v) was evaporated to a thickness of 10 nm to form a first electron transport layer, and 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P) represented by the above structural formula (vi) was evaporated to a thickness of 15 nm to form a second electron transport layer, thus forming the electron transport layer 114. The first electron transport layer also functions as a hole blocking layer.

[0424] Next, lithium fluoride (LiF) and ytterbium (Yb) were co-evaporated to a thickness of 1.5 nm so that the volume ratio was 1:0.5 (=LiF:Yb) to form the electron injection layer 115, and then silver (Ag) and magnesium (Mg) were co-evaporated to a volume ratio of 1:0.1 and a thickness of 25 nm to form the second electrode 102, thereby producing a light-emitting device according to one embodiment of the present invention. In addition, ITO was deposited to a thickness of 70 nm on the second electrode 102 as a cap layer to improve the light extraction efficiency.

[0425] Next, in a glove box with a nitrogen atmosphere, the light-emitting device was sealed with a glass substrate to prevent it from being exposed to the atmosphere (a UV-curable sealant was applied around the element, UV was irradiated only onto the sealant so as not to irradiate the light-emitting device, and a heat treatment was performed at 80°C under atmospheric pressure for 1 hour), thereby forming light-emitting device 1.

[0426] (Method of producing comparative light-emitting device 1) In the comparative light-emitting device 1, the first electrode to the hole transport layer were formed in the same manner as in the light-emitting device 1. Then, 8-(biphenyl-4-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8BP-4mDBtPBfpm) represented by the above structural formula (vii) and 9,9'-diphenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCP) represented by the above structural formula (viii) were formed on the hole transport layer. The light-emitting layer 113 was formed by co-depositing 40 nm of 8BP-4mDBtPBfpm:PCCP:Ir(ppy)2(mbfpypy-d3) and [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-d3)) represented by the above structural formula (ix) in a weight ratio of 0.6:0.4:0.1 (=8BP-4mDBtPBfpm:PCCP:Ir(ppy)2(mbfpypy-d3)).

[0427] After that, 2-[3-(3'-dibenzothiophen-4-yl)biphenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II) represented by the above structural formula (x) was evaporated to a thickness of 20 nm to form a first electron transport layer, and 2,9-di(naphthalene-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBPhen) represented by the above structural formula (xi) was evaporated to a thickness of 15 nm to form a second electron transport layer, thus forming the electron transport layer 114. The first electron transport layer also functions as a hole blocking layer.

[0428] Next, lithium fluoride (LiF) was evaporated to a thickness of 1 nm to form the electron injection layer 115, and then silver (Ag) and magnesium (Mg) were co-evaporated to a volume ratio of 1:0.1 and a thickness of 25 nm to form the second electrode 102, thereby producing a light-emitting device according to one embodiment of the present invention. In addition, ITO was deposited to a thickness of 70 nm on the second electrode 102 as a cap layer to improve the light extraction efficiency.

[0429] Next, in a glove box with a nitrogen atmosphere, the light-emitting device was sealed with a glass substrate to prevent it from being exposed to the atmosphere (a UV-curable sealant was applied around the element, and UV was irradiated only onto the sealant without irradiating the light onto the light-emitting device, followed by a heat treatment at 80°C under atmospheric pressure for 1 hour), thereby forming comparative light-emitting device 1.

[0430] The device structures of light-emitting device 1 and comparative light-emitting device 1 are shown below.

[0431] [Table 1]

[0432] The luminance-current density characteristics of the light-emitting device 1 and the comparative light-emitting device 1 are shown in FIG. 19, the current efficiency-luminance characteristics in FIG. 20, the luminance-voltage characteristics in FIG. 21, the current density-voltage characteristics in FIG. 22, and the emission spectrum in FIG. 23. 2 The values ​​of voltage, current, current density, CIE chromaticity, and current efficiency in the vicinity are shown below. The luminance, CIE chromaticity, and emission spectrum were measured at room temperature using a spectroradiometer (SR-UL1R, manufactured by Topcon Corporation).

[0433] [Table 2]

[0434] 19 to 23, it can be seen that the light-emitting device 1 is a light-emitting device having better efficiency and driving voltage than the comparative light-emitting device 1.

[0435] Next, the current density was 50 mA / cm 2 The results of measuring the change in luminance versus drive time when driven at a constant current are shown in Fig. 24. Fig. 24 shows that light-emitting device 1 has a lifespan that is about twice as long as that of comparative light-emitting device 1, making it a light-emitting device with a good lifespan.

[0436] Here, the light-emitting device 1 is a light-emitting device according to one embodiment of the present invention, which has in its light-emitting layer 8mpTP-4mDBtPBfpm as a first organic compound, βNCCP as a second organic compound, and Ir(5mppy-d3)2(mbfpypy-d3) as a phosphorescent light-emitting material.

[0437] 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 is an organic compound whose lowest triplet excitation level is derived from the terphenyl group. The second organic compound βNCCP has a bicarbazole skeleton and is an organic compound whose lowest triplet excitation energy is 2.55 eV (2.20 eV or more and 2.65 eV or less). Ir(5mppy-d3)2(mbfpypy-d3) is a phosphorescent material that exhibits green phosphorescence.

[0438] The lowest triplet excitation energy level (T1 level) of βNCCP was calculated by measuring the emission spectrum (phosphorescence spectrum) at a temperature of 10K using a thin film of βNCCP formed at 50 nm on a quartz substrate. The measurement was performed using a micro PL device LabRAM HR-PL (Horiba, Ltd.) and a He-Cd laser (325 nm) as the excitation light. As a result, the shortest wavelength peak of the emission spectrum (phosphorescence spectrum) of βNCCP was 491 nm (2.53 eV), and the shortest wavelength emission edge was 486 nm (2.55 eV). The emission edge was calculated by drawing a tangent at the value where the slope on the shortest wavelength side of the peak (or shoulder peak) observed at the shortest wavelength of the emission spectrum (phosphorescence spectrum) is maximum, and the tangent was calculated from the intersection point of the tangent with the horizontal axis (wavelength) or the baseline.

[0439] Similarly, the lowest triplet excitation energy level of PCCP was measured, and the emission edge on the shortest wavelength side of the emission spectrum of PCCP was found to be 454 nm (2.73 eV).

[0440] The first organic compound and the second organic compound in the light-emitting device 1 form an exciplex capable of exciting the green phosphorescent light-emitting material. In addition, the second organic compound has a relatively low T1 level of 2.55 eV, so that excitons in an excessively high energy state are not generated. In addition, the first organic compound also has the lowest triplet excitation level in a terphenyl group (particularly, a terphenyl group substituted at the meta position is preferable), so that the T1 level is not too high and is an appropriate value, as in the second organic compound. As a result, the light-emitting device 1 can be a light-emitting device with good reliability.

[0441] On the other hand, in the comparative light-emitting device 1, 8BP-4mDBtPBfpm, which corresponds to the first substance, is an organic compound that has a benzofuropyrimidine skeleton, which is a heteroaromatic ring skeleton, and a biphenyl group, which is an aromatic hydrocarbon group, but the lowest triplet excitation level is not derived from the biphenyl group but from the dibenzothiophenyl group. Therefore, the T1 level of 8BP-4mDBtPBfpm is higher than that of 8mpTP-4mDBtPBfpm, and high-energy excitons are generated. In addition, PCCP, which corresponds to the second organic compound, is an organic compound that has a bicarbazole skeleton, but has a lowest triplet excitation energy of 2.73 eV (2.65 eV or more). In addition, Ir(ppy)2(mbfpypy-d3) is a phosphorescent light-emitting substance that exhibits green phosphorescence.

[0442] The lowest triplet excitation energy levels (T1 levels) of 8mpTP-4mDBtPBfpm and 8BP-4mDBtPBfpm were measured in the same manner as for βNCCP. The shortest wavelength peak of the emission spectrum of 8mpTP-4mDBtPBfpm was 500 nm (2.48 eV), and the shortest wavelength emission end was 486 nm (2.55 eV). The shortest wavelength peak of the emission spectrum of 8BP-4mDBtPBfpm was 495 nm (2.51 eV), and the shortest wavelength emission end was 482 nm (2.57 eV). Therefore, it can be said that 8mpTP-4mDBtPBfpm is an organic compound with a lower lowest triplet excitation energy level than 8BP-4mDBtPBfpm. EXAMPLES

[0443] In this example, the results of analysis by calculation of a first organic compound that can be used in a light-emitting device of one embodiment of the present invention will be described with reference to FIGS.

[0444] The HOMO distribution, LUMO distribution, and localized state of the lowest triplet excited state were analyzed for 8mpTP-4mDBtPBfpm (structural formula (200)), which is one of the specific examples of the first organic compound, and the organic compound represented by structural formula (216), as well as 8BP-4mDBtPBfpm, which is a comparative example.

[0445] [ka]

[0446] <Calculation method> The analysis of the distribution of HOMO and LUMO was performed by vibration (spin density) analysis of the most stable structure with the lowest S0 level for the singlet ground state (S0) of the compound. The analysis of the localization of the lowest triplet excited state was performed by spin density analysis of the most stable structure with the lowest T1 level for the lowest triplet excited state (T1) of the compound. The calculation method used was density functional theory (DFT). The total energy calculated by DFT is expressed as the sum of potential energy, electrostatic energy between electrons, kinetic energy of electrons, and exchange-correlation energy including all complex interactions between electrons. In DFT, the exchange-correlation interaction is approximated by a functional (meaning a function of a function) of a single-electron potential expressed by electron density, so the calculation is fast. Here, the weights of each parameter related to the exchange and correlation energy were specified using the mixed functional B3LYP. In addition, 6-311G(d,p) was used as the basis function. Gaussian 09 was used as the calculation program.

[0447] The analysis results of 8mpTP-4mDBtPBfpm are shown in FIG. 25, the analysis results of the organic compound represented by the structural formula (216) are shown in FIG. 26, and the analysis results of 8BP-4mDBtPBfpm are shown in FIG. 27. In FIG. 25 to FIG. 27, the spheres in the figures represent the atoms constituting the compound, and the clouds around the atoms represent the spin density distribution when the spin density value is set to 0.003. In FIG. 25(A), FIG. 26(A), and FIG. 27(A), the clouds around the atoms represent the LUMO distribution in the molecule. In FIG. 25(B), FIG. 26(B), and FIG. 27(B), the clouds around the atoms represent the HOMO distribution in the molecule. In FIG. 25(C), FIG. 26(C), and FIG. 27(C), the clouds around the atoms represent the localized state of the lowest triplet excited state in the molecule.

[0448] 25 and 26, in 8mpTP-4mDBtPBfpm and the organic compound represented by structural formula (216), the lowest triplet excited state is localized in the terphenyl group corresponding to the first substituent of the first organic compound. Therefore, in 8mpTP-4mDBtPBfpm and the organic compound represented by structural formula (216), the lowest triplet excited state is localized in the 1,1':4',1''-terphenyl skeleton of the first substituent, and it was found that the T1 level of 8mpTP-4mDBtPBfpm and the organic compound represented by structural formula (216) is derived from the 1,1':4',1''-terphenyl skeleton.

[0449] On the other hand, as shown in Figure 27, the lowest triplet excited state of 8BP-4mDBtPBfpm is distributed not only in the 1,1'-biphenyl-4-yl group corresponding to the first substituent of the first organic compound, but also in the [1]benzofuro[3,2-d]pyrimidine ring corresponding to the electron transport skeleton. Therefore, it was found that the lowest triplet excited state of 8BP-4mDBtPBfpm is not localized in the first substituent. EXAMPLES

[0450] This example describes detailed manufacturing methods of a light-emitting device 2 which is a light-emitting device of one embodiment of the present invention and a comparative light-emitting device 2 which is a comparative light-emitting device, and also describes measurement results of initial characteristics and reliability thereof.

[0451] The structural formulae of the main compounds used in the present examples are shown below.

[0452] [ka]

[0453] (Method of manufacturing light-emitting device 2) First, 100 nm of silver (Ag) and 10 nm of indium tin oxide containing silicon oxide (ITSO) were sequentially laminated on a glass substrate by sputtering from the substrate side to form a first electrode 101 having a size of 2 mm x 2 mm. The ITSO functions as an anode and is regarded as the first electrode 101 together with the Ag.

[0454] Next, as a pretreatment for forming a light-emitting device on the substrate, the surface of the substrate was washed with water.

[0455] After that, about 1 × 10 -4 The substrate was introduced into a vacuum deposition apparatus whose inside had been reduced in pressure to 10 Pa, and vacuum baking was carried out at 170° C. for 60 minutes in a heating chamber in the vacuum deposition apparatus, and then the substrate was allowed to cool for about 30 minutes.

[0456] Next, the substrate was fixed to a holder installed in a vacuum deposition apparatus so that the surface on which the first electrode 101 was formed was facing downward, and N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF) represented by the above structural formula (i) and an electron acceptor material (OCHD-003) containing fluorine and having a molecular weight of 672 were co-deposited by a deposition method to a thickness of 10 nm on the inorganic insulating film and the first electrode 101 in a weight ratio of 1:0.03 (=PCBBiF:OCHD-003) to form a hole injection layer 111.

[0457] On the hole injection layer 111, PCBBiF was evaporated to a thickness of 15 nm to form a hole transport layer 112.

[0458] Subsequently, 8-(1,1':4',1''-terphenyl-3-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm) represented by the above structural formula (ii), 9-(2-naphthyl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: βNCCP) represented by the above structural formula (iii), and [2-d3- The light-emitting layer 113 was formed by co-evaporating 40 nm of methyl-8-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN2)phenyl-κC]iridium(III) (abbreviation: Ir(5mppy-d3)2(mbfpypy-d3)) and βNCCP in a weight ratio of 0.5:0.5:0.1 (=8mpTP-4mDBtPBfpm:βNCCP:Ir(5mppy-d3)2(mbfpypy-d3)).

[0459] After that, 2-{3-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}dibenzo[f,h]quinoxaline (abbreviation: 2mPCCzPDBq) represented by the above structural formula (v) was deposited to a thickness of 10 nm to form a first electron transport layer, and 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P) represented by the above structural formula (vi) was deposited to a thickness of 20 nm to form a second electron transport layer, thus forming the electron transport layer 114. The first electron transport layer also functions as a hole blocking layer.

[0460] Next, lithium fluoride (LiF) and ytterbium (Yb) were co-evaporated to a thickness of 1.5 nm so that the volume ratio was 1:0.5 (=LiF:Yb) to form the electron injection layer 115, and then silver (Ag) and magnesium (Mg) were co-evaporated to a volume ratio of 1:0.1 and a film thickness of 15 nm to form the second electrode 102, thereby producing a light-emitting device according to one embodiment of the present invention. In addition, 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) represented by the above structural formula (xii) was formed to a thickness of 70 nm on the second electrode 102 as a cap layer to improve the light extraction efficiency.

[0461] Next, in a glove box with a nitrogen atmosphere, the light-emitting device was sealed with a glass substrate to prevent it from being exposed to the atmosphere (a UV-curable sealant was applied around the element, UV was irradiated only onto the sealant so as not to irradiate the light-emitting device, and a heat treatment was performed at 80°C under atmospheric pressure for 1 hour), forming light-emitting device 2.

[0462] (Method of producing comparative light-emitting device 2) Comparative light-emitting device 2 was prepared in the same manner as light-emitting device 2, except that 8mpTP-4mDBtPBfpm in light-emitting device 2 was changed to 8-(biphenyl-4-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8BP-4mDBtPBfpm) represented by the above structural formula (vii).

[0463] The device structures of light-emitting device 2 and comparative light-emitting device 2 are shown below.

[0464] [Table 3]

[0465] The luminance-current density characteristics of the light-emitting device 2 and the comparative light-emitting device 2 are shown in FIG. 28, the current efficiency-luminance characteristics in FIG. 29, the luminance-voltage characteristics in FIG. 30, the current density-voltage characteristics in FIG. 31, and the emission spectrum in FIG. 32.2 The values ​​of voltage, current, current density, CIE chromaticity, and current efficiency in the vicinity are shown below. The luminance, CIE chromaticity, and emission spectrum were measured at room temperature using a spectroradiometer (SR-UL1R, manufactured by Topcon Corporation).

[0466] [Table 4]

[0467] 28 to 32, it is apparent that both the light emitting device 2 and the comparative light emitting device 2 are light emitting devices having excellent characteristics.

[0468] Next, the current density of the light-emitting device 2 and the comparative light-emitting device 2 was 50 mA / cm 2 The results of measuring the change in luminance versus drive time during constant current drive are shown in Fig. 33. Fig. 33 shows that the time until luminance deteriorates by 10% (LT90) was 263 hours for light-emitting device 2 and 232 hours for comparative light-emitting device 2, indicating that light-emitting device 2 has a longer life than comparative light-emitting device 2.

[0469] Here, the light-emitting device 2 is a light-emitting device according to one embodiment of the present invention, which has in its light-emitting layer 8mpTP-4mDBtPBfpm as a first organic compound, βNCCP as a second organic compound, and Ir(5mppy-d3)2(mbfpypy-d3) as a phosphorescent light-emitting material.

[0470] 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 is an organic compound whose lowest triplet excitation level is derived from the terphenyl group. The second organic compound βNCCP has a bicarbazole skeleton and is an organic compound whose lowest triplet excitation energy is 2.55 eV (2.20 eV or more and 2.65 eV or less). Ir(5mppy-d3)2(mbfpypy-d3) is a phosphorescent material that exhibits green phosphorescence.

[0471] The lowest triplet excitation energy level (T1 level) of βNCCP was calculated by measuring the emission spectrum (phosphorescence spectrum) at a temperature of 10K using a thin film of βNCCP formed at 50 nm on a quartz substrate. The measurement was performed using a micro PL device LabRAM HR-PL (Horiba, Ltd.) and a He-Cd laser (325 nm) as the excitation light. As a result, the shortest wavelength peak of the emission spectrum (phosphorescence spectrum) of βNCCP was 491 nm (2.53 eV), and the shortest wavelength emission edge was 486 nm (2.55 eV). The emission edge was calculated by drawing a tangent at the value where the slope on the shortest wavelength side of the peak (or shoulder peak) observed at the shortest wavelength of the emission spectrum (phosphorescence spectrum) is maximum, and the tangent was calculated from the intersection point of the tangent with the horizontal axis (wavelength) or the baseline.

[0472] The first organic compound and the second organic compound in the light-emitting device 2 form an exciplex capable of exciting the green phosphorescent light-emitting material. In addition, the second organic compound has a relatively low T1 level of 2.55 eV, so that excitons in an excessively high energy state are not generated. In addition, in the first organic compound, the lowest triplet excitation level is present in a terphenyl group (particularly, a terphenyl group substituted at the meta position is preferable), so that the T1 level is not too high and is an appropriate value, as in the second organic compound. This allows the light-emitting device 2 to be a light-emitting device with good reliability.

[0473] On the other hand, in the comparative light-emitting device 2, 8BP-4mDBtPBfpm, which corresponds to the first substance, is an organic compound that has a benzofuropyrimidine skeleton, which is a heteroaromatic ring skeleton, and a biphenyl group, which is an aromatic hydrocarbon group, but the lowest triplet excitation level is not derived from the biphenyl group but from the dibenzothiophenyl group. Therefore, the T1 level of 8BP-4mDBtPBfpm is higher than that of 8mpTP-4mDBtPBfpm, and high-energy excitons are generated.

[0474] The lowest triplet excitation energy levels (T1 levels) of 8mpTP-4mDBtPBfpm and 8BP-4mDBtPBfpm were measured in the same manner as for βNCCP. The shortest wavelength peak of the emission spectrum of 8mpTP-4mDBtPBfpm was 500 nm (2.48 eV), and the shortest wavelength emission end was 486 nm (2.55 eV). The shortest wavelength peak of the emission spectrum of 8BP-4mDBtPBfpm was 495 nm (2.51 eV), and the shortest wavelength emission end was 482 nm (2.57 eV). Therefore, it can be said that 8mpTP-4mDBtPBfpm is a material with a lower lowest triplet excitation energy level than 8BP-4mDBtPBfpm. EXAMPLES

[0475] Example 1 This example describes a detailed manufacturing method of a light-emitting device 3 and a light-emitting device 4, which are light-emitting devices according to one embodiment of the present invention, and also describes measurement results of their initial characteristics and reliability.

[0476] The structural formulae of the main compounds used in the present examples are shown below.

[0477] [ka]

[0478] (Method of manufacturing light-emitting device 3) First, 100 nm of silver (Ag) and 10 nm of indium tin oxide containing silicon oxide (ITSO) were sequentially laminated on a glass substrate by sputtering from the substrate side to form a first electrode 101 having a size of 2 mm x 2 mm. The ITSO functions as an anode and is regarded as the first electrode 101 together with the Ag.

[0479] Next, as a pretreatment for forming a light-emitting device on the substrate, the surface of the substrate was washed with water.

[0480] After that, about 1 × 10 -4The substrate was introduced into a vacuum deposition apparatus whose inside had been reduced in pressure to 10 Pa, and vacuum baking was carried out at 170° C. for 60 minutes in a heating chamber in the vacuum deposition apparatus, and then the substrate was allowed to cool for about 30 minutes.

[0481] Next, the substrate was fixed to a holder installed in a vacuum deposition apparatus so that the surface on which the first electrode 101 was formed was facing downward, and N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF) represented by the above structural formula (i) and an electron acceptor material (OCHD-003) containing fluorine and having a molecular weight of 672 were co-deposited by a deposition method to a thickness of 10 nm on the inorganic insulating film and the first electrode 101 in a weight ratio of 1:0.03 (=PCBBiF:OCHD-003) to form a hole injection layer 111.

[0482] On the hole injection layer 111, PCBBiF was evaporated to a thickness of 10 nm to form a hole transport layer 112.

[0483] Subsequently, 8-(1,1':4',1''-terphenyl-3-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm) represented by the above structural formula (ii), 9-(2-naphthyl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: βNCCP) represented by the above structural formula (iii), and [2-d3- The light-emitting layer 113 was formed by co-evaporating 50 nm of methyl-8-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN2)phenyl-κC]iridium(III) (abbreviation: Ir(5mppy-d3)2(mbfpypy-d3)) and βNCCP in a weight ratio of 0.5:0.5:0.1 (=8mpTP-4mDBtPBfpm:βNCCP:Ir(5mppy-d3)2(mbfpypy-d3)).

[0484] After that, 2-{3-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}dibenzo[f,h]quinoxaline (abbreviation: 2mPCCzPDBq) represented by the above structural formula (v) was evaporated to a thickness of 10 nm to form a first electron transport layer, and 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P) represented by the above structural formula (vi) was evaporated to a thickness of 10 nm to form a second electron transport layer, thus forming the electron transport layer 114. The first electron transport layer also functions as a hole blocking layer.

[0485] Next, lithium fluoride (LiF) and ytterbium (Yb) were co-evaporated to a thickness of 1.5 nm so that the volume ratio was 1:0.5 (=LiF:Yb) to form the electron injection layer 115, and then silver (Ag) and magnesium (Mg) were co-evaporated to a volume ratio of 1:0.1 and a film thickness of 25 nm to form the second electrode 102, thereby producing a light-emitting device according to one embodiment of the present invention. In addition, 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) represented by the above structural formula (xii) was formed to a thickness of 70 nm on the second electrode 102 as a cap layer to improve the light extraction efficiency.

[0486] Next, in a glove box with a nitrogen atmosphere, the light-emitting device was sealed with a glass substrate to prevent it from being exposed to the atmosphere (a UV-curable sealant was applied around the element, UV was irradiated only onto the sealant so as not to irradiate the light-emitting device, and heat treatment was performed at 80°C under atmospheric pressure for 1 hour), thereby forming light-emitting device 3.

[0487] (Method of manufacturing light-emitting device 4) The light-emitting device 4 is a light-emitting device 3 in which 8mpTP-4mDBtPBfpm is replaced 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-(dibenzothiophen-4-yl-1,2,3,6,7,8,9-d7)phenyl-2,4,6-d3]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm-d 23 ) was used, the light-emitting device was fabricated in the same manner as in device 3.

[0488] The device structures of light-emitting device 3 and light-emitting device 4 are shown below.

[0489] [Table 5]

[0490] 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-luminance characteristics in FIG. 35, the luminance-voltage characteristics in FIG. 36, the current density-voltage characteristics in FIG. 37, and the emission spectrum in FIG. 38. 2 The values ​​of voltage, current, current density, CIE chromaticity, and current efficiency in the vicinity are shown below. The luminance, CIE chromaticity, and emission spectrum were measured at room temperature using a spectroradiometer (SR-UL1R, manufactured by Topcon Corporation).

[0491] [Table 6]

[0492] 34 to 38, it is apparent that both the light emitting device 3 and the light emitting device 4 are light emitting devices having excellent characteristics.

[0493] Next, the current density of light-emitting device 3 and light-emitting device 4 was 50 mA / cm 2 The results of measuring the change in luminance versus drive time when driven at a constant current are shown in Fig. 39. As can be seen from Fig. 39, the luminance after 250 hours was 90% of the initial luminance for light-emitting device 3 and 92% for light-emitting device 4, indicating that both light-emitting devices 3 and 4 are light-emitting devices with good reliability, but that light-emitting device 4 in particular has a longer life.

[0494] Here, the light-emitting device 3 is a light-emitting device according to one embodiment of the present invention, which has in its light-emitting layer 8mpTP-4mDBtPBfpm as a first organic compound, βNCCP as a second organic compound, and Ir(5mppy-d3)2(mbfpypy-d3) as a phosphorescent material. The light-emitting device 4 has in its light-emitting layer 8mpTP-4mDBtPBfpm-d 23 1 is a light-emitting device according to one embodiment of the present invention, which includes βNCCP as the second organic compound and Ir(5mppy-d3)2(mbfpypy-d3) as a phosphorescent light-emitting substance.

[0495] That is, the first organic compound 8mpTP-4mDBtPBfpm or 8mpTP-4mDBtPBfpm-d 23 is an organic compound having a benzofuropyrimidine skeleton, which is a heteroaromatic ring skeleton, a terphenyl group, which is an aromatic hydrocarbon group, and the lowest triplet excitation level is derived from the terphenyl group. The second organic compound, βNCCP, is an organic compound having a bicarbazole skeleton and a lowest triplet excitation energy of 2.55 eV (2.20 eV or more and 2.65 eV or less). Ir(5mppy-d3)2(mbfpypy-d3) is a phosphorescent material that exhibits green phosphorescence.

[0496] The lowest triplet excitation energy level (T1 level) of βNCCP was calculated by measuring the emission spectrum (phosphorescence spectrum) at a temperature of 10K using a thin film of βNCCP formed at 50 nm on a quartz substrate. The measurement was performed using a micro PL device LabRAM HR-PL (Horiba, Ltd.) and a He-Cd laser (325 nm) as the excitation light. As a result, the shortest wavelength peak of the emission spectrum (phosphorescence spectrum) of βNCCP was 491 nm (2.53 eV), and the shortest wavelength emission edge was 486 nm (2.55 eV). The emission edge was calculated by drawing a tangent at the value where the slope on the shortest wavelength side of the peak (or shoulder peak) observed at the shortest wavelength of the emission spectrum (phosphorescence spectrum) is maximum, and the tangent was calculated from the intersection point of the tangent with the horizontal axis (wavelength) or the baseline.

[0497] 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 light-emitting material. In addition, the second organic compound has a relatively low T1 level of 2.55 eV, so that excitons in an excessively high energy state are not generated. In addition, in the first organic compound, the lowest triplet excitation level is present in a terphenyl group (particularly, a terphenyl group substituted at the meta position is preferable), so that the T1 level is not too high and is an appropriate value, as in the second organic compound. As a result, the light-emitting device 3 and the light-emitting device 4 can be made into light-emitting devices with good reliability.

[0498] In the same manner as βNCCP, 8mpTP-4mDBtPBfpm and 8mpTP-4mDBtPBfpm-d 23 The lowest triplet excitation energy level (T1 level) of 8mpTP-4mDBtPBfpm was measured, and the shortest wavelength peak of the emission spectrum of 8mpTP-4mDBtPBfpm was 500 nm (2.48 eV), and the shortest wavelength emission edge was 486 nm (2.55 eV). 23 The peak on the shortest wavelength side of the emission spectrum was 501 nm (2.48 eV), and the emission edge on the shortest wavelength side was 484 nm (2.56 eV).

[0499] Next, 8mpTP-4mDBtPBfpm and 8mpTP-4mDBtPBfpm-d 23 The respective 2Me-THF solutions were cooled with liquid nitrogen, and the emission spectra and emission quantum yields were measured.

[0500] The emission spectra and quantum yields were measured using an absolute PL quantum yield measurement device (Hamamatsu Photonics C11347-01) in a glove box (Bright LABstar M13 (1250 / 780)) under a nitrogen atmosphere for 8mpTP-4mDBtPBfpm and 8mpTP-4mDBtPBfpm-d. 23Each 2Me-THF deoxygenated solution (0.120 mmol / L) was placed in a quartz cell, sealed, and cooled with liquid nitrogen for measurement. 23 The measurement results of the emission spectrum are shown in Figure 40. The horizontal axis represents the wavelength, and the vertical axis represents the emission intensity.

[0501] As shown in Figure 40, the emission spectrum of a mixture of fluorescence and phosphorescence was observed in all samples. The spectrum around 351 nm to 455 nm was confirmed to be fluorescence based on the room temperature measurement and the emission lifetime measurement results. In addition, the spectrum around 455 nm to 660 nm was confirmed to be derived from phosphorescence because it was only observed in the low temperature measurement.

[0502] In addition, the measurement results of the luminescence quantum yield showed that the quantum yield (Φ f The quantum yield (Φ p (H)) was found to be 10%.

[0503] In addition, the emission quantum yield measurement results showed that 8mpTP-4mDBtPBfpm-d 23 The quantum yield (Φ f The quantum yield (Φ p (D)) was found to be 15%.

[0504] That is, at low temperatures (temperatures cooled with liquid nitrogen), 8mpTP-4mDBtPBfpm-d 23 It was found that the quantum yield of the phosphorescent component of was 1.5 times that of the phosphorescent component of 8mpTP-4mDBtPBfpm, and the quantum yield of the fluorescent component was almost the same.

[0505] Also, 8mpTP-4mDBtPBfpm and 8mpTP-4mDBtPBfpm-d 23 The results of measuring the luminescence lifetime when each 2-methyltetrahydrofuran (2Me-THF) solution was cooled with liquid nitrogen are shown.

[0506] A fluorometer (FP-8600, manufactured by JASCO Corporation) was used to measure the luminescence lifetime. 23 Each 2Me-THF solution (0.120 mmol / L) was placed in a quartz cell and cooled with liquid nitrogen for measurement. In this measurement, the wavelength of the excitation light was 320 nm and the wavelength of the measurement light was 515 nm. The excitation light was irradiated onto the quartz cell containing the solution for about 30 seconds, and the excitation light was blocked with a shutter, after which the decaying emission intensity was measured at 10 ms intervals for time-resolved measurement. The bandwidth of the excitation light and measurement light was 10 nm. The obtained time decay curve is shown in Figure 41. The horizontal axis represents time, and the vertical axis represents emission intensity.

[0507] As shown in FIG. 41, the luminescence intensity was found to decay in a single exponential manner. The luminescence lifetime was calculated from the obtained decay curve. The luminescence lifetime of 8mpTP-4mDBtPBfpm was 2.8 s. 23 The luminescence lifetime of was 5.3 s. Since the wavelength of the light used to measure the luminescence lifetime 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 form was 1.9 times longer than that of the non-deuterated form.

[0508] Here, the phosphorescence quantum yield (Φ p ) and phosphorescence lifetime (τ p ) is the radiative transition rate constant k from the lowest triplet excited state (T1) of an organic compound rp and the nonradiative transition rate constant k nrp , and the quantum yield of intersystem crossing from the lowest singlet excited state (S1) to the lowest triplet excited state (T1) (Φ isc ) can be expressed as the following equations (1) and (2).

[0509]

number

[0510] From this formula, k rp and k nrp can be expressed using Φ and τ as the following equations (3) and (4), respectively.

[0511]

number

[0512] Here, from the above measurement results, deuterated 8mpTP-4mDBtPBfpm-d 23 Phosphorescence quantum yield Φ p (D) The phosphorescence quantum yield Φ of undeuterated 8mpTP-4mDBtPBfpm p 1.5 times larger than (H), 8mpTP-4mDBtPBfpm-d 23 Phosphorescence lifetime τ p (D) The phosphorescence lifetime τ of 8mpTP-4mDBtPBfpm p It is known that the value is 1.9 times that of (H). 23 Fluorescence quantum yield Φ f (D) and the fluorescence quantum yield Φ of 8mpTP-4mDBtPBfpm f (H) was almost the same.

[0513] At the temperature cooled by liquid nitrogen, the rate constant of the nonradiative transition of fluorescence is much smaller than the rate constants of the radiative transition and intersystem crossing. 23 The quantum yield Φ of intersystem crossing isc (H) and Φ isc (D) shows the fluorescence quantum yield (Φ f (H), Φ f Using (D), Φ isc (H)=1-Φ f(H) Φ isc (D)=1-Φ f (D) and Φ f (H) and Φ f (D) was almost the same value, so Φ isc (H) and Φ isc (D) can be considered the same.

[0514] 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), the rate constant of the radiative transition is k rp (H), the rate constant of the nonradiative transition is k nrp (H) 8mpTP-4mDBtPBfpm-d 23 The phosphorescence quantum yield of Φ p (D) The rate constant is τ p (D) The quantum yield of intersystem crossing is Φ isc (D) The rate constant of the radiative transition is k rp (D) The rate constant of the nonradiative transition is k nrp (D) Then, k rp (H) is the following formula (3-1), k rp (D) is the following formula (3-2), k nrp (H) is the following formula (4-1), k nrp (D) can be expressed as the following equation (4-2).

[0515]

number

[0516] In this way, k nrp (D) is k nrp (H) is 0.50 times, k nrp (D) <k nrp (H) and k rp (D) is k rp (H) is 0.79 times, k rp (D) <k rp(H), and compared to 8mpTP-4mDBtPBfpm, the deuterated 8mpTP-4mDBtPBfpm-d 23 It was found that both the rate constants of the nonradiative transition and the radiative transition are small, but since the rate constant of the nonradiative transition is smaller than the rate constant of the radiative transition, it was found that the nonradiative transition is more suppressed than the radiative transition.

[0517] In this way, the deuterated organic compound has smaller rate constants for radiative transition and non-radiative transition, but the non-radiative transition is more suppressed, so that the generated triplet excitons can undergo radiative transition in a larger number. Since the radiative transition is a transition related to energy transfer, the deuterated organic compound has improved energy transfer efficiency for transferring the excitation energy to another compound (here, the phosphorescent material, which is the guest material) compared to the non-deuterated organic compound. The improved energy transfer efficiency makes it possible to suppress the deterioration of the deuterated organic compound, and a light-emitting device using the organic compound as a host material can be a light-emitting device with good reliability because the deterioration of the host material is suppressed.

[0518] At low temperatures (temperatures cooled with liquid nitrogen), 23 The rate constant k for the radiative transition of rp (D) is the rate constant k of the radiative transition of 8mpTP-4mDBtPBfpm rp (H), the nonradiative transition rate constant k nrp (D) is k nrp (H), the rate constant of the nonradiative transition is relatively low, k nrp The decrease in (D) is larger. Therefore, the rate constant of the radiative transition k rp Even considering the decrease in (D), 8mpTP-4mDBtPBfpm-d 23 Since the proportion of triplet excitons that undergo radiative transition increases in the nucleon, it can be said that deuteration improves the efficiency of energy transfer.

[0519] In addition, the fluorescence quantum yield was 8mpTP-4mDBtPBfpm-d 23 There was almost no difference between 8mpTP-4mDBtPBfpm and 8mpTP-4mDBtPBfpm. In addition, the rate constant of the non-radiative transition at the low temperature of 77K is very small compared to the rate constants of the radiative transition and intersystem crossing. This suggests that deuteration of 8mpTP-4mDBtPBfpm-d 23 There was no significant difference in the rate constants of the radiative and nonradiative transitions in the fluorescence emission process of 8mpTP-4mDBtPBfpm, and it can be said that the effect of deuteration mainly affects the behavior of triplet excitons.

[0520] Here, 8mpTP-4mDBtPBfpm-d, in which only the first substituent of 8mpTP-4mDBtPBfpm was replaced with deuterium, is 13 (Structural formula (223)) and 8mpTP-4mDBtPBfpm-d, in which only the second substituent is deuterium-substituted. 10 The same measurement was performed on (structural formula (225)) and the results were: 8mpTP-4mDBtPBfpm-d 10 (Structural formula (225)) is equivalent to 8mpTP-4mDBtPBfpm, 8mpTP-4mDBtPBfpm-d 13 (Structural formula (223)) is 8mpTP-4mDBtPBfpm-d 23 showed equivalent results.

[0521] [ka]

[0522] 8mpTP-4mDBtPBfpm-d 23 The results were equivalent to 8mpTP-4mDBtPBfpm-d 13is an organic compound in which only the first substituent of the first organic compound is replaced with deuterium. Therefore, it has become clear that the first organic compound can suppress the non-radiative transition in the phosphorescence emission process by replacing only the first substituent with deuterium. This is thought to be because T1 is localized in the first substituent in the first organic compound, and by deuterizing the first substituent, the intramolecular vibration in the lowest triplet excited state is suppressed, thereby suppressing the non-radiative transition from T1 of the first organic compound, which is consistent with the previous result (the fluorescence quantum yield and fluorescence lifetime are unchanged, and only the phosphorescence quantum yield and phosphorescence lifetime are changed).

[0523] In addition, the energy transfer efficiency from the host material to the guest material, φ ET From the viewpoint of energy transfer efficiency φ ET is expressed by the following formula (5), and the energy transfer efficiency φ ET To increase the rate constant of energy transfer, k h*→g becomes large and other competing rate constants k r +k nr It can be seen that it is good if (=1 / τ) becomes relatively small.

[0524] In addition, in formula (5), k r represents the rate constant of the light emission process of the host material (fluorescence when energy transfer from a singlet excited state is considered, and phosphorescence when energy transfer from a triplet excited state is considered), and k nr represents the rate constant of the non-radiative processes (thermal deactivation and intersystem crossing) of the host material, and τ represents the lifetime of the excited state of the host material measured. h*→g represents the rate constant for energy transfer (Förster or Dexter mechanism).

[0525]

number

[0526] Energy transfer rate constant k h*→g is a deuterated organic compound (8mpTP-4mDBtPBfpm-d23 In the case of an organic compound (8mpTP-4mDBtPBfpm) that is not deuterated, the atomic arrangement of the molecules and the spectral shape are almost the same, so the two materials are almost identical (see formula (6) or (7) below). Therefore, when comparing deuterated organic compounds with non-deuterated organic compounds, it can be seen that the luminescence lifetime (phosphorescence lifetime) τ has a large effect.

[0527] As mentioned above, the phosphorescence lifetime measured at low temperatures (temperatures cooled with liquid nitrogen) is consistent with that of deuterated organic compounds (8mpTP-4mDBtPBfpm-d 23 ) was 1.9 times that of the non-deuterated organic compound (8mpTP-4mDBtPBfpm). Assuming that there is a difference in the phosphorescence lifetime between deuterated and non-deuterated organic compounds even at room temperature, the energy transfer efficiency from the host material to the guest material, φ ET From formula (5), the deuterated organic compound (8mpTP-4mDBtPBfpm-d 23 It can be said that a light-emitting device using the organic compound (8mpTP-4mDBtPBfpm) as a host material has improved energy transfer efficiency compared to a light-emitting device using an organic compound (8mpTP-4mDBtPBfpm) that is not used as a host material.

[0528] The improvement in the energy transfer efficiency makes it possible to suppress the deterioration of the deuterated organic compound, and therefore, a light-emitting device using a deuterated organic compound as a host material can be made to have a higher reliability because the deterioration of the host material is suppressed compared to a light-emitting device using a non-deuterated organic compound as the host material.

[0529]

number

[0530]

number

[0531] Equation (6) is the rate constant k for the Förster mechanism, and equation (7) is the rate constant k for the Dexter mechanism. h*→g This is the formula.

[0532] In formula (6), ν represents the frequency, and f′ h (ν) represents the normalized emission spectrum of the host material (fluorescence spectrum when discussing energy transfer from a singlet excited state, and phosphorescence spectrum when discussing energy transfer from a triplet excited state), and ε g (ν) represents the molar absorption coefficient of the guest material, N represents Avogadro's number, n represents the refractive index of the medium, R represents the intermolecular distance between the host material and the guest material, τ represents the measured excited state lifetime (fluorescence lifetime, phosphorescence lifetime), φ represents the luminescence quantum yield (fluorescence quantum yield when discussing energy transfer from a singlet excited state, and phosphorescence quantum yield when discussing energy transfer from a triplet excited state), and K 2 is a coefficient (0 to 4) that represents the orientation of the transition dipole moment of the host material and the guest material. In the case of random orientation, K 2 =2 / 3.

[0533] In equation (7), h is the Planck constant, K is a constant with the dimension of energy, ν is the frequency, and f′ h (ν) represents the normalized emission spectrum of the host material (fluorescence spectrum when discussing energy transfer from a singlet excited state, and phosphorescence spectrum when discussing energy transfer from a triplet excited state), and ε′ g (ν) represents the normalized absorption spectrum of the guest material, L represents the effective molecular radius, and R represents the intermolecular distance between the host material and the guest material.

[0534] In addition, when the energy of triplet excitons is high, the long lifetime of the excitons may accelerate deterioration. However, in one embodiment of the present invention, since the first organic compound is a material with a relatively low T1 level, the effect of the long lifetime of triplet excitons on reliability is small. Furthermore, it has been found that a substance in which the first and second substituents in the first organic compound (host material) are deuterated suppresses non-radiative transitions, thereby increasing the efficiency of energy transfer from the substance to the light-emitting material and improving the reliability of the light-emitting device. EXAMPLES

[0535] In this example, a detailed manufacturing method of light-emitting devices 5 to 7, which are light-emitting devices according to one embodiment of the present invention, and measurement results of their initial characteristics and reliability will be described.

[0536] The structural formulae of the main compounds used in the present examples are shown below.

[0537] [ka]

[0538] (Method of Manufacturing Light-Emitting Device 5) First, 50 nm of titanium (Ti), 70 nm of aluminum (Al), and 6 nm of titanium (Ti) were laminated in this order by sputtering on a silicon substrate with wiring. This was then heat-treated in air at 300°C for 1 hour. After the heat treatment and cleaning, a 10 nm film of indium tin oxide (ITSO) containing silicon oxide was formed by sputtering. This laminated film was patterned by photolithography to form the first electrode. The transparent electrode functions as an anode and is considered to be the first electrode together with the reflective electrode.

[0539] The area of ​​the first electrode is 4 mm 2 (2mm x 2mm).

[0540] 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 onto the substrate heated to 60°C for 120 seconds. This makes it possible to make the laminated film formed on the first electrode less likely to peel off from the first electrode during the manufacturing process.

[0541] After that, about 1 × 10 -4 The substrate was introduced into a vacuum deposition apparatus whose inside had been reduced in pressure to 1 Pa, and vacuum baking was carried out at 170° C. for 60 minutes in a heating chamber in the vacuum deposition apparatus, and then the substrate was allowed to cool for about 60 minutes.

[0542] Next, the substrate was fixed to a holder installed in a vacuum deposition apparatus so that the surface on which the first electrode 101 was formed was facing downward, and N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF) represented by the above structural formula (i) and an electron acceptor material (OCHD-003) containing fluorine and having a molecular weight of 672 were co-deposited by a deposition method to a thickness of 10 nm on the inorganic insulating film and the first electrode 101 in a weight ratio of 1:0.03 (=PCBBiF:OCHD-003) to form a hole injection layer 111.

[0543] On the hole injection layer 111, PCBBiF was evaporated to a thickness of 10 nm to form a hole transport layer 112.

[0544] Subsequently, 8-(1,1':4',1''-terphenyl-3-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm) represented by the above structural formula (ii), 9-(2-naphthyl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: βNCCP) represented by the above structural formula (iii), and [2-d3- The light-emitting layer 113 was formed by co-evaporating 40 nm of methyl-8-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN2)phenyl-κC]iridium(III) (abbreviation: Ir(5mppy-d3)2(mbfpypy-d3)) and βNCCP in a weight ratio of 0.6:0.4:0.1 (=8mpTP-4mDBtPBfpm:βNCCP:Ir(5mppy-d3)2(mbfpypy-d3)).

[0545] After that, 2-{3-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}dibenzo[f,h]quinoxaline (abbreviation: 2mPCCzPDBq) represented by the above structural formula (v) was deposited to a thickness of 10 nm to form a first electron transport layer, and 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P) represented by the above structural formula (vi) was deposited to a thickness of 15 nm to form a second electron transport layer, thereby forming electron transport layer 114.

[0546] Subsequently, processing was performed by photolithography. The substrate on which the electron transport layer 114 had been formed was removed from the vacuum deposition apparatus and exposed to the atmosphere, after which aluminum oxide was deposited by ALD to a thickness of 30 nm to form a first sacrificial layer. Trimethylaluminum (abbreviation: TMA) was used as a precursor and water vapor was used as an oxidizing agent to deposit the aluminum oxide by the ALD method.

[0547] A tungsten (W) film was formed on the first sacrificial layer by sputtering to a thickness of 54 nm to form a second sacrificial layer.

[0548] Photoresist is applied onto the second sacrificial layer, exposed, and developed, and the processed photoresist is processed into a shape that covers the first electrode and has an end that is 3.5 μm outward from the end of the first electrode, with a 3.0 μm wide slit positioned thereon.

[0549] Using the processed photoresist as a mask, the second sacrificial layer was processed using an etching gas containing SF6, and using the second sacrificial layer as a hard mask, the first sacrificial layer was processed using an etching gas containing fluoroform (CHF3), helium (He), and methane (CH4) with a flow rate ratio of CHF3:He:CH4 = 16.5:118.5:15. After this, the EL layer (hole injection layer, hole transport layer, light emitting layer, electron transport layer) was processed using an etching gas containing oxygen (O2).

[0550] After processing the EL layer, the second sacrificial layer was removed using an etching gas containing SF6, leaving the first sacrificial layer, which was then removed using an aqueous solution containing hydrofluoric acid (HF) to expose the electron transport layer.

[0551] The substrate with the second electron transport layer exposed was then immersed in 1×10 -4 The mixture was introduced into a vacuum deposition apparatus whose inside had been reduced in pressure to about Pa, and vacuum baking was carried out at 70° C. for 90 minutes in a heating chamber in the vacuum deposition apparatus.

[0552] Next, lithium fluoride (LiF) and ytterbium (Yb) were co-evaporated to a thickness of 1.5 nm so that the volume ratio was 1:0.5 (=LiF:Yb) to form the electron injection layer 115, and then silver (Ag) and magnesium (Mg) were co-evaporated to a volume ratio of 1:0.1 and a thickness of 25 nm to form the second electrode 102, thereby manufacturing a light-emitting device according to one embodiment of the present invention. In addition, a 70-nm thick film of indium tin oxide (ITO) was formed on the second electrode as a cap layer by a sputtering method.

[0553] Next, in a glove box with a nitrogen atmosphere, the light-emitting device was sealed with a glass substrate to prevent it from being exposed to the atmosphere (a UV-curable sealant was applied around the element, UV was irradiated only onto the sealant so as not to irradiate the light-emitting device, and heat treatment was performed at 80°C under atmospheric pressure for 1 hour), thereby forming light-emitting device 5.

[0554] (Method of manufacturing light-emitting device 6) Light-emitting device 6 was fabricated in the same manner as light-emitting device 5, except that the light-emitting layer was formed by co-evaporation of 8mpTP-4mDBtPBfpm, βNCCP, and tris{2-[5-(methyl-d3)-4-phenyl-2-pyridinyl-κN]phenyl-κC}iridium(III) (abbreviation: Ir(5m4dppy-d3)3) represented by the above structural formula (xiv) to a thickness of 40 nm, in a weight ratio of 0.6:0.4:0.1 (=8mpTP-4mDBtPBfpm:βNCCP:Ir(5m4dppy-d3)3).

[0555] (Method of Manufacturing Light-Emitting Device 7) The light-emitting device 7 is a light-emitting device 6 having a structure in which 8mpTP-4mDBtPBfpm is replaced 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-(dibenzothiophen-4-yl-1,2,3,6,7,8,9-d7)phenyl-2,4,6-d3]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm-d 23 ) was used, the light-emitting device was fabricated in the same manner as in device 6.

[0556] The device structures of light-emitting devices 5 to 7 are shown below.

[0557] [Table 7]

[0558] [Table 8]

[0559] The current efficiency-luminance characteristics of light-emitting devices 5 to 7 are shown in Fig. 42, the luminance-voltage characteristics in Fig. 43, the current efficiency-current density characteristics in Fig. 44, the current density-voltage characteristics in Fig. 45, the luminance-current density characteristics in Fig. 46, the electroluminescence spectra in Fig. 47, and the main initial characteristics in Table 9. The luminance, CIE chromaticity, and emission spectra were measured at room temperature using a spectroradiometer (SR-UL1R, manufactured by Topcon Corporation).

[0560] [Table 9]

[0561] 42 to 47 and Table 9 show that light-emitting devices 5 to 7 are all light-emitting devices having excellent characteristics.

[0562] Next, the current density of the light-emitting devices 5 to 7 was 50 mA / cm 2 The results of measuring the change in luminance versus drive time when driven at a constant current in the above-mentioned device are shown in Fig. 48. As can be seen from Fig. 48, all of the light-emitting devices 5 to 7 have good reliability, and light-emitting device 7 in particular has a longer life.

[0563] Here, light-emitting device 5 is a light-emitting device according to one embodiment of the present invention, having an emission layer containing 8mpTP-4mDBtPBfpm as a first organic compound, βNCCP as a second organic compound, and Ir(5mppy-d3)2(mbfpypy-d3) as a phosphorescent material. Light-emitting device 6 is a light-emitting device according to one embodiment of the present invention, having an emission layer containing 8mpTP-4mDBtPBfpm as a first organic compound, βNCCP as a second organic compound, and Ir(5m4dppy-d3)3 as a phosphorescent material. Light-emitting device 7 is a light-emitting device according to one embodiment of the present invention, having an emission layer containing 8mpTP-4mDBtPBfpm-d 231 is a light-emitting device according to one embodiment of the present invention, which has βNCCP as the second organic compound and Ir(5m4dppy-d3)3 as a phosphorescent light-emitting substance.

[0564] That is, the first organic compound 8mpTP-4mDBtPBfpm or 8mpTP-4mDBtPBfpm-d 23 is an organic compound having a benzofuropyrimidine skeleton, which is a heteroaromatic ring skeleton, a terphenyl group, which is an aromatic hydrocarbon group, and the lowest triplet excitation level is derived from the terphenyl group. The second organic compound, βNCCP, is an organic compound having a bicarbazole skeleton and a lowest triplet excitation energy of 2.55 eV (2.20 eV or more and 2.65 eV or less). Ir(5mppy-d3)2(mbfpypy-d3) and Ir(5m4dppy-d3)3 are phosphorescent luminescent materials that exhibit green phosphorescence.

[0565] The lowest triplet excitation energy level (T1 level) of βNCCP was calculated by measuring the emission spectrum (phosphorescence spectrum) at a temperature of 10K using a thin film of βNCCP formed at 50 nm on a quartz substrate. The measurement was performed using a micro PL device LabRAM HR-PL (Horiba, Ltd.) and a He-Cd laser (325 nm) as the excitation light. As a result, the shortest wavelength peak of the emission spectrum (phosphorescence spectrum) of βNCCP was 491 nm (2.53 eV), and the shortest wavelength emission edge was 486 nm (2.55 eV). The emission edge was calculated by drawing a tangent at the value where the slope on the shortest wavelength side of the peak (or shoulder peak) observed at the shortest wavelength of the emission spectrum (phosphorescence spectrum) is maximum, and the tangent was calculated from the intersection point of the tangent with the horizontal axis (wavelength) or the baseline.

[0566] 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 light-emitting material. In addition, the second organic compound has a relatively low T1 level of 2.55 eV, so that excitons in an excessively high energy state are not generated. In addition, the first organic compound also has the lowest triplet excitation level in a terphenyl group (particularly, a terphenyl group substituted at the meta position is preferable), so that the T1 level is not too high and is an appropriate value, as in the second organic compound. For this reason, the light-emitting devices 5 to 7 can be light-emitting devices with good reliability.

[0567] In the same manner as βNCCP, 8mpTP-4mDBtPBfpm and 8mpTP-4mDBtPBfpm-d 23 The lowest triplet excitation energy level (T1 level) of 8mpTP-4mDBtPBfpm was measured, and the shortest wavelength peak of the emission spectrum of 8mpTP-4mDBtPBfpm was 500 nm (2.48 eV), and the shortest wavelength emission edge was 486 nm (2.55 eV). 23 The peak on the shortest wavelength side of the emission spectrum was 501 nm (2.48 eV), and the emission edge on the shortest wavelength side was 484 nm (2.56 eV). [Explanation of symbols]

[0568] 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 membrane 103G EL layer 103Gf EL membrane 103R EL layer 103Rf EL membrane 103 EL layer 104 Common layer 105 Insulators 110B subpixel 110G subpixel 110R subpixel 110 subpixels 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 type 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 layers 129B Conductive layer 129R conductive layer 130B Light Emitting Device 130G Light Emitting Device 130R Light Emitting Device 130 Light Emitting Devices 131 Protective layer 132B Colored layer 132G colored layer 132R colored layer 140 Connection 141 areas 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 Insulation layer 156R Insulation layer 156 Insulating Layer 157 Light blocking layer 158B Sacrificial Layer 158Bf sacrificial film 158f Sacrificial membrane 158G Sacrificial Layer 158Gf sacrificial film 158R Sacrificial layer 158Rf Sacrificial film 159B Mask layer 159Bf Mask membrane 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 section 178 pixels 179 Conductive Layer 190B Resist mask 190G Resist Mask 190R Resist Mask 191 Resist Mask 201 Transistor 204 Connection 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 capacity 241 Conductive Layer 242 Connection Layer 243 Insulating Layer 245 Conductive Layer 254 Insulating layer 255 Insulation 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 pixels 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 blocking layer 351 Substrate 352 Substrate 353 FPC 354 IC 355 Wiring 356 circuits 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 section 603 Gate line driving circuit 604 Sealing substrate 605 Sealing material 607 Space 608 Wiring 610 Element Substrate 611 Switching FET 612 Current Control FET 613 First electrode 614 Insulation 616 EL layer 617 Second Electrode 618 Light Emitting Devices 623 FET 700A electronic equipment 700B Electronic equipment 721 Case 723 Mounting Part 727 Earphones 750 Earphones 751 Display Panel 753 Optical Components 756 Display area 757 Frames 758 Nose pad 800A electronic equipment 800B Electronic equipment 820 Display section 821 Case 822 Communications Department 823 Mounting part 824 Control Unit 825 Imaging unit 827 Earphones 832 Lens 6500 Electronic equipment 6501 Case 6502 Display section 6503 Power button 6504 Button 6505 Speaker 6506 Microphone 6507 Camera 6508 Light source 6510 Protective materials 6511 Display Panel 6512 Optical components 6513 Touch Sensor Panel 6515 FPC 6516 IC 6517 Printed Circuit Board 6518 Battery 7000 Display 7100 Television equipment 7151 Remote control device 7171 Case 7173 Stand 7200 Notebook Personal Computer 7211 Case 7212 Keyboard 7213 Pointing Device 7214 External connection port 7300 Digital Signage 7301 Case 7303 Speaker 7311 Information terminal 7400 Digital Signage 7401 Pillar 7411 Information terminal 9000 Chassis 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 9172 Mobile Information Terminal 9173 Tablet PC 9200 Mobile Information Terminal 9201 Mobile information terminals

Claims

1. It comprises a first electrode, a second electrode, and a light-emitting layer. The light-emitting layer is located 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 excited state of the first organic compound is localized to the aromatic hydrocarbon group, A light-emitting device wherein 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.

2. It comprises a first electrode, a second electrode, and a light-emitting layer. The light-emitting layer is located 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 substituents, 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 excitation level of the second organic compound is 2.20 eV or more and 2.65 eV or less.

3. In claim 2, A light-emitting device in which the substituent comprises one or both of a dibenzofuran skeleton and a dibenzothiophene skeleton.

4. In claim 3, A light-emitting device in which the 1,1':4',1''-terphenyl skeleton is substituted for the hetero-aromatic ring skeleton at the 3-position.

5. In claim 3, A light-emitting device in which the substituent is substituted on the heteroaromatic ring skeleton via a 1,3-phenylene group.

6. In claim 3, A light-emitting device in which the lowest triplet excitation level of the first organic compound is derived from the substituent.

7. It comprises a first electrode, a second electrode, and a light-emitting layer. The light-emitting layer is located 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 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 excitation level of the second organic compound is 2.20 eV or more and 2.65 eV or less.

8. In claim 7, A light-emitting device in which the 1,1':4',1''-terphenyl group is substituted for the heteroaromatic ring skeleton at the 3-position.

9. In claim 7, 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.

10. In claim 7, A light-emitting device in which the lowest triplet excitation level of the first organic compound is derived from the 1,1':4',1''-terphenyl group.

11. In any one of claims 1 to 10, The aforementioned complex aromatic ring skeleton is a light-emitting device containing a fused ring.

12. In any one of claims 1 to 10, The aforementioned complex aromatic ring skeleton is a light-emitting device containing a diazine skeleton.

13. In any one of claims 1 to 10, The aforementioned heteroaromatic ring skeleton comprises a fused ring and a diazine skeleton in this light-emitting device.

14. In any one of claims 1 to 10, The aforementioned heteroaromatic ring skeleton is a luminescent device having a benzophropyrimidine skeleton or a triazine skeleton.

15. In any one of claims 1 to 10, The second organic compound is a light-emitting device having a naphthyl group.

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