Light emitting device

Abstract

To provide a novel light-emitting device. A light-emitting device with a long driving lifetime at high temperatures is provided.SOLUTION: An organic light-emitting element includes an anode, a cathode, and an electroluminescent (EL) layer located between the anode and the cathode, the EL layer including a first layer, a second layer, and a third layer from the anode side, the first layer including a first organic compound and a second organic compound, the second layer including a third organic compound, the third layer including a fourth organic compound, the EL layer including a fifth organic compound and a luminescent center substance, wherein the first organic compound is a material exhibiting an electron-accepting property with respect to the second organic compound, and a difference between a HOMO level of the fourth material and a HOMO level of the fifth organic compound is 0.24 eV or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One aspect of the present invention is a light-emitting element, a light-emitting device, a display module, and a lighting module. The present invention relates to a display device, a light-emitting device, an electronic device, and a lighting device. The technical field of one embodiment of the invention disclosed in the present specification and the like is not limited to the following: Alternatively, one aspect of the present invention relates to a process, a machine, , manufacture, or composition of matter Therefore, the technical field of one embodiment of the present invention disclosed in this specification more specifically includes: Semiconductor device, display device, liquid crystal display device, light-emitting device, lighting device, power storage device, memory device, imaging device Examples include devices, methods for driving them, and methods for manufacturing them. . [Background technology]

[0002] Electroluminescence (EL) using organic compounds Light-emitting devices (organic EL elements) that utilize these luminescence are being put to practical use. The basic structure of the device is a pair of electrodes sandwiching an organic compound layer (EL layer) containing a light-emitting material. When a voltage is applied to this element, carriers are injected and the recombination of these carriers occurs. By utilizing the energy, light can be emitted from the light-emitting material.

[0003] Since such light-emitting devices are self-luminous, when they are used as pixels in a display, It has advantages such as high visibility and no need for backlighting compared to flat panel displays. The light-emitting device is suitable for use as a display element. Another major advantage is that it can be manufactured to be thin and lightweight. It is one of the signs.

[0004] In addition, these light-emitting devices can be fabricated with a continuous two-dimensional light-emitting layer. This is a point light source, such as an incandescent bulb or LED, and This is a feature that is difficult to obtain with linear light sources such as fluorescent lamps, so it is used as a surface light source that can be applied to lighting, etc. It is also highly useful as a tool.

[0005] Displays and lighting devices using such light-emitting devices are suitable for use in a variety of electronic devices. However, research and development is being conducted to find light-emitting devices with better efficiency and life span. There are.

[0006] In Patent Document 1, a first hole injection layer is provided between a first hole transport layer in contact with the hole injection layer and a light emitting layer. Hole transport properties with a HOMO level between that of the interlayer and that of the host material A configuration for applying the material is disclosed.

[0007] The properties of light-emitting devices have improved dramatically, but many other properties, including efficiency and durability, remain. It must be said that this is still insufficient to meet the high level of demands on the environment. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication No. 2011 / 065136 Brochure Summary of the Invention [Problem to be solved by the invention]

[0009] In view of the above, an object of one embodiment of the present invention is to provide a novel light-emitting device. The object is to provide a light-emitting device having a good operating life even at high temperatures.

[0010] In another embodiment of the present invention, a light-emitting device and an electronic device having a long operating life at high temperatures are provided. and a display device.

[0011] The present invention is intended to solve any one of the above problems. [Means for solving the problem]

[0012] One aspect of the present invention is a light-emitting diode (LED) having an anode, a cathode, and an EL layer located between the anode and the cathode. The EL layer has, from the anode side, a first layer, a second layer, a third layer, and a light-emitting layer. The first layer has a first organic compound and a second organic compound, and the second layer has , a third organic compound, the third layer comprising a fourth organic compound, and the light-emitting layer comprising a fifth organic compound and a luminescent center substance, and the first organic compound is a substance that exhibits electron accepting properties to the compound, and The difference between the HOMO level of the organic compound of formula 5 and that of the organic compound of formula 6 is 0.24 eV or less.

[0013] Another embodiment of the present invention is a compound having the above structure, wherein the HOMO level of the second organic compound is −5 It is a light-emitting device with a photosensitivity of -0.7eV or more and -5.4eV or less.

[0014] Another aspect of the present invention is a light-emitting diode (LED) comprising an anode, a cathode, and an EL layer located between the anode and the cathode. The EL layer has, from the anode side, a first layer, a third layer, and a light-emitting layer, The first layer has a first organic compound and a second organic compound, and the third layer has a fourth organic compound. the light-emitting layer comprises a fifth organic compound and a luminescent center substance, The first organic compound is a substance that exhibits electron accepting properties to the second organic compound, and the second The organic compound has a HOMO level of -5.7 eV or more and -5.4 eV or less, and the fourth The difference between the HOMO level of the organic compound and the HOMO level of the fifth organic compound is 0.24 eV. A light emitting device comprising:

[0015] Another embodiment of the present invention is a compound having the above-described structure, wherein the HOMO level of the fifth organic compound is −5 It is a light-emitting device with a photodiode energy of 0.75 eV or less.

[0016] Another aspect of the present invention is, in the above-mentioned configuration, the fifth organic compound having multiple molecules in its molecular structure. The light-emitting device does not contain an aromatic ring.

[0017] Another aspect of the present invention is the method for manufacturing a liquid crystal display device according to the above aspect, wherein the fifth organic compound is composed of only hydrocarbons. It is a light-emitting device.

[0018] Another embodiment of the present invention is a method for manufacturing a semiconductor device having the above-described structure, wherein the HOMO level of the fourth organic compound and the The fifth organic compound has a difference of 0.20 eV or less from its HOMO level. .

[0019] Another embodiment of the present invention is a method for manufacturing a semiconductor device having the above-described structure, wherein the HOMO level of the fourth organic compound and the The fifth organic compound has a difference of 0.16 eV or less from its HOMO level. .

[0020] Alternatively, in the above-described configuration, another aspect of the present invention is a method for manufacturing a light emitting device, wherein the luminescence center substance has a wavelength of 480 nm or less. The light-emitting device emits fluorescence having an emission peak wavelength of

[0021] Alternatively, in another aspect of the present invention, in the above-mentioned configuration, the luminescent center substance is naphthobisbenzyl. A light-emitting device having a zofran skeleton.

[0022] Another embodiment of the present invention is a semiconductor device including the above light-emitting device, a transistor, or a substrate, and The light emitting device has the following.

[0023] Another embodiment of the present invention is a light-emitting device including the above-described light-emitting device and a sensor, an operation button, a speaker, or the like. Or, it is an electronic device having a microphone.

[0024] Another embodiment of the present invention is a lighting device including the above-described light-emitting device and a housing.

[0025] In this specification, the term "light-emitting device" includes an image display device using a light-emitting device. In addition, a connector such as anisotropic conductive film or TCP (Tape) is attached to the light-emitting device. Module with Carrier Package attached, printed on TCP Modules with wiring boards or light-emitting devices with COG (Chip On Glass) s) method, a module in which an IC (integrated circuit) is directly mounted may also be included in the category of light-emitting device. Furthermore, lighting fixtures and the like may include a light-emitting device. [Effects of the Invention]

[0026] According to one embodiment of the present invention, a novel light-emitting device can be provided. It is possible to provide a light-emitting device with a good operating life.

[0027] In another embodiment of the present invention, a light-emitting device and an electronic device having a long operating life at high temperatures are provided. and a display device, respectively.

[0028] The description of these effects does not preclude the existence of other effects. The embodiment does not necessarily have to have all of these effects. , the specification, drawings, claims, etc., and It is possible to extract other effects from the claims and other descriptions. [Brief explanation of the drawings]

[0029] [Figure 1] Schematic of a light-emitting device. [Figure 2] 1 is a conceptual diagram of an active matrix light-emitting device. [Figure 3] 1 is a conceptual diagram of an active matrix light-emitting device. [Figure 4] 1 is a conceptual diagram of an active matrix light-emitting device. [Figure 5] FIG. 1 is a conceptual diagram of a passive matrix light-emitting device. [Figure 6] FIG. [Figure 7] 1 is a diagram showing an electronic device. [Figure 8] 1 is a diagram showing an electronic device. [Figure 9] FIG. [Figure 10] FIG. [Figure 11] FIG. 2 is a diagram illustrating an in-vehicle display device and an illumination device. [Figure 12] 1 is a diagram showing an electronic device. [Figure 13] 1 is a diagram showing an electronic device. [Figure 14] Luminance-current density characteristics of Light-emitting Device 1 and Comparative Light-emitting Device 1. [Figure 15] Current efficiency-luminance characteristics of light-emitting device 1 and comparative light-emitting device 1. [Figure 16] Luminance-voltage characteristics of light-emitting device 1 and comparative light-emitting device 1. [Figure 17] Current-voltage characteristics of light-emitting device 1 and comparative light-emitting device 1. [Figure 18] Power efficiency-luminance characteristics of Light-emitting Device 1 and Comparative Light-emitting Device 1. [Figure 19] External quantum efficiency-luminance characteristics of Light-emitting Device 1 and Comparative Light-emitting Device 1. [Figure 20] 1 shows the emission spectra of light-emitting device 1 and comparative light-emitting device 1. [Figure 21] Normalized luminance vs. time change characteristics of light-emitting device 1 and comparative light-emitting device 1. [Figure 22] Luminance-current density characteristics of light-emitting device 2 and comparative light-emitting device 2. [Figure 23] Current efficiency-luminance characteristics of light-emitting device 2 and comparative light-emitting device 2. [Figure 24] Luminance-voltage characteristics of light-emitting device 2 and comparative light-emitting device 2. [Figure 25] Current-voltage characteristics of light-emitting device 2 and comparative light-emitting device 2. [Figure 26] Power efficiency-luminance characteristics of light-emitting device 2 and comparative light-emitting device 2. [Figure 27] External quantum efficiency-luminance characteristics of light-emitting device 2 and comparative light-emitting device 2. [Figure 28] 1 shows the emission spectra of light-emitting device 2 and comparative light-emitting device 2. [Figure 29] Normalized luminance-time change characteristics of light-emitting device 2 and comparative light-emitting device 2. [Figure 30] Luminance-current density characteristics of light-emitting device 3 and light-emitting device 4. [Figure 31] Current efficiency-luminance characteristics of light-emitting device 3 and light-emitting device 4. [Figure 32] Luminance-voltage characteristics of light-emitting device 3 and light-emitting device 4. [Figure 33] Current-voltage characteristics of light-emitting device 3 and light-emitting device 4. [Figure 34] Power efficiency-luminance characteristics of light-emitting device 3 and light-emitting device 4. [Figure 35] External quantum efficiency-luminance characteristics of light-emitting device 3 and light-emitting device 4. [Figure 36] Emission spectra of light-emitting device 3 and light-emitting device 4. [Figure 37] Normalized luminance vs. time change characteristics of light-emitting device 3 and light-emitting device 4. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the above description, and the form and details thereof may be changed without departing from the spirit and scope of the present invention. It will be readily apparent to those skilled in the art that various modifications may be made to the present invention. It should not be construed as being limited to the description of the embodiments.

[0031] (Embodiment 1) In the organic EL device, a positive electrode is placed in contact with the anode to facilitate carrier injection from the anode. A hole injection layer is often provided.

[0032] The hole injection layer contains a material (acceptor material) that has a high ability to accept electrons from organic compounds. The acceptor material can be either an organic compound or an inorganic compound. However, organic compounds are becoming increasingly popular as acceptor materials because they are easy to vaporize and handle. It is used in

[0033] On the other hand, the acceptor properties of organic compounds are not as high as those of inorganic compounds. Therefore, it is known that the hole injection layer is formed by mixing the acceptor material with the The materials used for forming the hole transport layer and the adjacent hole transport layer are those that attract electrons. To facilitate extraction, a hole transport material with a shallow HOMO level is selected. HOMO level of the hole transport material used in the adjacent hole transport layer in relation to the driving voltage, etc. also tends to be shallower.

[0034] In the blue fluorescent light-emitting device, the luminescent center substance that emits blue fluorescence is effectively excited. To achieve this, it is common to use a host material with a deep HOMO level. In a light-emitting device using the above-mentioned organic compound acceptor material, the positive electrode in contact with the light-emitting layer The HOMO level of the hole transport material used in the hole transport layer and electron blocking layer and the H The inventors have found that this difference is due to the It was found that this has a significant impact on the operating life.

[0035] FIG. 21(B) shows a hole transport layer (or electron blocking layer) used in the hole transport layer (or electron blocking layer) in contact with the light emitting layer. The difference between the HOMO levels of the transport material and the host material is greater than 0.24 eV The light-emitting device (comparison light-emitting device 1) and the light-emitting device (light-emitting device 2) with a peak voltage of 0.24 eV or less were Figure 2 shows the change in brightness over time for a device 1) at room temperature. 1(A) shows the results of driving a device with the same device structure at a high temperature of 85°C. The figures below show the change in brightness over time. The values ​​are normalized by the degree of polarization. For details of the device structure, see Example 1. stomach.

[0036] In FIG. 21(B), which shows the results of operation at room temperature, the lifetime of the comparative light-emitting device 1 is longer than that of the light-emitting device Although the lifespan of the device exceeds that of the device described above, the results of operation at high temperatures in Figure 21(A) show that the lifespan of the device is significantly shorter than that of the device described above. It can be seen that the lifetime of the comparative light-emitting device 1 is significantly shorter than that of the light-emitting device 1. The degradation curve of light-emitting device 1 follows a single exponential function at both room temperature and high temperature. The shape of the degradation curve at high temperatures for Light-emitting Device 1 deviates from a single exponential function. This indicates that the degradation of Comparative Light-Emitting Device 1 progresses through a different mechanism when operated at high temperatures. This suggests the possibility that

[0037] 1A1 and 1A2 are diagrams illustrating a light-emitting device according to one embodiment of the present invention. The light-emitting device has an anode 101, a cathode 102, and an EL layer 103. The layers include a hole injection layer 111 , a hole transport layer 112 and an emissive layer 113 .

[0038] In addition to these, the EL layer 103 in FIGS. 1(A1) and 1(A2) also includes an electron transport layer 11 4 and electron injection layer 115 are shown, the configuration of the light-emitting device of the present invention is not limited to this. As long as the above-mentioned structure is maintained, layers having other functions may be included. stomach.

[0039] The hole injection layer 111 includes a first organic compound and a second organic compound. The compound is a substance that exhibits electron accepting properties toward the second organic compound.

[0040] The first organic compound has an electron-withdrawing group (particularly a halogen group such as a fluoro group or a cyano group). Among such substances, the second organic compound A substance that exhibits electron-accepting properties can be appropriately selected. Examples of such organic compounds include: For example, 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-T CNNQ), 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octa Fluoro-7H-pyren-2-ylidene)malononitrile, etc. Compounds such as HAT-CN in which electron-withdrawing groups are bonded to fused aromatic rings containing multiple heteroatoms The compound is thermally stable and is therefore preferred. Radialene derivatives containing benzophenone or cyano groups are preferred because of their high electron-accepting properties. Specifically, α,α',α''-1,2,3-cyclopropanetriylidenetris[ 4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α',α ''-1,2,3-Cyclopropanetriylidenetris[2,6-dichloro-3,5-di Fluoro-4-(trifluoromethyl)benzeneacetonitrile], α,α',α''- 1,2,3-Cyclopropanetriylidenetris[2,3,4,5,6-pentafluoro Benzeneacetonitrile], etc.

[0041] The second organic compound is preferably an organic compound having hole transport properties, and The structure is selected from the group consisting of dibenzofuran, dibenzothiophene, and anthracene skeletons. In particular, it is preferable that the compound has a dibenzofuran ring or a dibenzothiophene ring. aromatic monoamines having a naphthalene ring, or aromatic monoamines having a 9- It was an aromatic monoamine in which the fluorenyl group was attached to the amine nitrogen through an arylene group. It is also possible to use the second organic compound as a compound having an N,N-bis(4-biphenyl)amino group. A material having the formula (I) is preferable because it allows a light-emitting device with a long lifetime to be manufactured. Specific examples of the second organic compound include N-(4-biphenyl)-6, N-Diphenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BnfA BP), N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2- d]Furan-8-amine (abbreviation: BBABnf), 4,4'-bis(6-phenylbenzo[a]thiazolinone) [b]naphtho[1,2-d]furan-8-yl)-4''-phenyltriphenylamine (abbreviation: BnfBB1BP), N,N-bis(4-biphenyl)benzo[b]naphtho[1 ,2-d]furan-6-amine (abbreviation: BBABnf(6)), N,N-bis(4-bifuran) phenyl)benzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf( 8)), N,N-bis(4-biphenyl)benzo[b]naphtho[2,3-d]furan-4 -amine (abbreviation: BBABnf(II)(4)), N,N-bis[4-(dibenzofuran -4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP), N-[4-(dibenzothiophen-4-yl)phenyl]-N-phenyl-4-biphenyl ThBA1BP, 4-(2-naphthyl)-4',4''-diphenyl Triphenylamine (abbreviation: BBAβNB), 4-[4-(2-naphthyl)phenyl]- 4',4''-Diphenyltriphenylamine (abbreviation: BBAβNBi), 4‐(2;1 '-Binaphthyl-6-yl)-4',4''-diphenyltriphenylamine (abbreviation: B BAαNβNB), 4,4'-diphenyl-4''-(7;1'-binaphthyl-2-yl ) Triphenylamine (abbreviation: BBAαNβNB-03), 4,4'-diphenyl-4' '-(7-phenyl)naphthyl-2-yltriphenylamine (abbreviation: BBAPβNB- 03), 4-(6;2'-binaphthyl-2-yl)-4',4''-diphenyltriphenyl Binaphthylamine (abbreviation: BBA(βN2)B), 4-(2;2'-binaphthyl-7-yl)- 4',4''-Diphenyltriphenylamine (abbreviation: BBA(βN2)B-03), 4 -(1;2'-binaphthyl-4-yl)-4',4''-diphenyltriphenylamine (abbreviation: BBAβNαNB), 4-(1;2′-binaphthyl-5-yl)-4′,4″ -Diphenyltriphenylamine (abbreviation: BBAβNαNB-02), 4-(4-biphenyl) 4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: TP BiAβNB), 4-(3-biphenylyl)-4'-[4-(2-naphthyl)phenyl] -4''-phenyltriphenylamine (abbreviation: mTPBiAβNBi), 4-(4-bi (phenylyl)-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenyl TPBiAβNBi, 4-(1-naphthyl)-4'-phenyltrifluoromethyl Phenylamine (abbreviation: αNBA1BP), 4,4'-bis(1-naphthyl)triphenyl Amine (abbreviation: αNBB1BP), 4,4'-diphenyl-4''-[4'-(carbazo (4-yl)biphenyl-9-yl)triphenylamine (abbreviation: YGTBi1BP ), 4'-[4-(3-phenyl-9H-carbazol-9-yl)phenyl]tris( 1,1'-biphenyl-4-yl)amine (abbreviation: YGTBi1BP-02), 4-[4 '-(carbazol-9-yl)biphenyl-4-yl]-4'-(2-naphthyl)-4 ''-Phenyltriphenylamine (abbreviation: YGTBiβNB), N-[4-(9-phenyl N-[4-(1-naphthyl)phenyl-9H-carbazol-3-yl]phenyl [9H-fluorenyl]-9,9'-spirobi[9H-fluoren]-2-amine (abbreviation: PCBNBSF) , N,N-bis([1,1'-biphenyl]-4-yl)-9,9'-spirobi[9H- fluorene]-2-amine (abbreviation: BBASF), N,N-bis([1,1'-biphenyl BB ASF(4)), N-(1,1'-biphenyl-2-yl)-N-(9,9-dimethyl- 9H-Fluoren-2-yl)-9,9'-spirobi[9H-fluoren]-4-amine (abbreviation: oFBiSF), N-(4-biphenyl)-N-(9,9-dimethyl-9H-furan) Fluoren-2-yl)dibenzofuran-4-amine (abbreviation: FrBiF), N-[4-( 1-naphthyl)phenyl]-N-[3-(6-phenyldibenzofuran-4-yl)phenyl] nyl]-1-naphthylamine (abbreviation: mPDBfBNBN), 4-phenyl-4'-(9 -phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4- phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mB PAFLP), 4-phenyl-4'-[4-(9-phenylfluoren-9-yl)phenyl] 4-phenyl-4'-(9-phenyl)triphenylamine (abbreviation: BPAFLBi), (9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)trimethylsilyl Phenylamine (abbreviated as PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl)amine (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 -9,9'-spirobi[9H-fluorenyl-9H-carbazol-3-ylphenyl] N-(1,1'-biphenyl-4-yl)-2-amine (abbreviation: PCBASF) 9,9-dimethyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl] Examples include [9H-fluoren-2-amine]-9H-fluoren-2-amine (abbreviation: PCBBiF).

[0042] The second organic compound has a HOMO level of -5.7 eV or higher, as in the above-mentioned materials. It is preferable that the material has a relatively deep HOMO level of 0.4 eV or less. The HOMO level of the organic compound of the first organic compound is such that holes are easily induced. It is preferably lower than the UMO level, more preferably 0.15 eV or more, and even more preferably It is preferable that the value is at least 0.20 eV lower.

[0043] The hole transport layer 112 includes a first hole transport layer 112-1 and a second hole transport layer 112-2. The first hole transport layer 112-1 is closer to the anode 101 than the second hole transport layer 112-2. It shall be located to the side.

[0044] The first hole transport layer 112-1 has a third organic compound, and the second hole transport layer 112-2 The third organic compound and the fourth organic compound have hole transport properties. The third organic compound and the fourth organic compound are preferably organic compounds having the above structure. The organic compounds that can be used as the second organic compound can be used in the same manner. In this case, the HOMO level of the third organic compound is set to be the same as or slightly higher than the HOMO level of the second organic compound. The HOMO level of the fourth organic compound is about the same as that of the third organic compound. It is preferable that the HOMO level of the second organic compound is the same as or deeper than the HOMO level of the third organic compound. The difference between the HOMO level of the third organic compound and the HOMO level of the fourth organic compound. The difference between the HOMO levels of each of these is preferably 0.2 eV or less.

[0045] In addition, each of the second to fourth organic compounds preferably has a hole transporting skeleton. The hole transporting skeleton is preferably formed by adding an organic compound having a HOMO level that is too shallow. Carbazole skeleton, dibenzofuran skeleton, dibenzothiophene skeleton and anthracene skeleton In addition, the hole transporting skeleton is preferably a material of adjacent layers (for example, the second (organic compound and third organic compound or third organic compound and fourth organic compound) In particular, the hole transporting skeleton is preferably is preferably a dibenzofuran skeleton.

[0046] In addition, materials contained in adjacent layers (for example, a second organic compound and a third organic compound or a If the organic compound (3) and the organic compound (4) are the same material, hole injection becomes smoother. This is a preferable configuration. In particular, when the second organic compound and the third organic compound are the same material, The configuration is preferred.

[0047] Here, the HOMO level of the second organic compound is relatively high, that is, in the range of −5.7 eV to −5.4 eV. Due to the deep HOMO level, the hole transport layer 112 can be formed into two layers as shown in FIG. 1(A1). As shown in FIG. 1(A2), a light-emitting device having good characteristics can be formed as a single layer. That is, the first hole transport layer 112-1 is not provided, and the hole injection layer 1 The second hole transport layer 112-2 is provided in contact with the second organic compound HO. Since the MO level is deep, the difference with the HOMO level of the host material is small, and the hole transport layer 112 This is because a light-emitting device according to one embodiment of the present invention can be realized even if the layer has a single layer structure. be.

[0048] It is preferable that the second hole transport layer 112-2 also functions as an electron blocking layer. .

[0049] The light-emitting layer 113 contains a fifth organic compound and a luminescent center substance. The fifth organic compound is It is a host material for dispersing the luminescent center substance.

[0050] The luminescent center substance can be a fluorescent substance, a phosphorescent substance, or a thermally activated delayed fluorescence. The material may be a material exhibiting TADF (Transparent Active Layer Doping) or other light-emitting materials. The light-emitting device of the present invention may be made up of a single layer or a plurality of layers containing different light-emitting materials. In one embodiment, the light-emitting layer 113 is a layer that exhibits fluorescent emission, particularly a layer that exhibits blue fluorescent emission. It is sometimes preferable.

[0051] In the light-emitting layer 113, materials that can be used as fluorescent materials include, for example: Examples include the following: Other fluorescent materials can also be used.

[0052] 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine PAP2BPy, 5,6-bis[4'-(10-phenyl-9-anthracene] N, N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl] )phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-biphenyl bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluorene 9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn ), N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-di Phenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-carbazo (4'-(10-phenyl-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation Name: YGAPA), 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl N,9-diphenyl-2-anthryltriphenylamine (abbreviation: 2YGAPPA) N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole -3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetra(tert- Butyl)perylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)-4'- (9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA PA), 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]chryse N-(9,10,15-tetraamine (abbreviation: DBC1), Coumarin 30, 10-Diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazole-3- Amine (abbreviation: 2PCAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)] [N,9-diphenyl-9H-carbazol-3-amine (abbreviated as 2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine] :2PCABPhA), N-(9,10-diphenyl-2-anthryl)-N,N',N '-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,1 0-Bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,N',N'-t Triphenyl-1,4-phenylenediamine (abbreviation: 2DPABPhA), 9,10-bis (1,1'-biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl] N,N-phenylanthracen-2-amine (abbreviation: 2YGABPhA), ,9-triphenylanthracene-9-amine (abbreviation: DPhAPhA), Coumarin 54 5T, N,N'-diphenylquinacridone, (abbreviation: DPQd), rubrene, 5,12- Bis(1,1'-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: B PT), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl -4H-pyran-4-ylidene)propanedinitrile (abbreviation: DCM1), 2-{2-methyl- 6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolinyl] {4H-pyran-4-ylidene}propanedinitrile (abbreviated :DCM2), N,N,N',N'-tetrakis(4-methylphenyl)tetracene-5 ,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N',N '-Tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3, 10-diamine (abbreviation: p-mPhAFD), 2-{2-isopropyl-6-[2-(1 ,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[i j]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinite 2-(2-tert-butyl-6-[2-(1,1,7,7 -Tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizidine 4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB), 2-(2,6-bis{2-[4-(dimethylamino)phenyl]ethenyl }-4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDCM), 2-{ 2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7- Tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H- Pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJ™), N,N'-( Pyrene-1,6-diyl)bis[(6,N-diphenylbenzo[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]na Futo[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10FrA2Nbf( IV)-02) and others. In particular, 1,6FLPAPrn and 1,6mMemFLP Condensation reactions represented by pyrene diamine compounds such as APrn and 1,6BnfAPrn-03 Aromatic diamine compounds have high hole trapping properties, and are excellent in luminous efficiency and reliability. preferable.

[0053] In the light-emitting layer 113, when a phosphorescent material is used as the light-emitting center material, it is possible to use Possible materials include, for example:

[0054] Tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H -1,2,4-triazol-3-yl-κN2]phenyl-κC}iridium(III ) (abbreviation: [Ir(mpptz-dmp)3]), tris(5-methyl-3,4-diphenyl Iridium(III) (abbreviation: [Ir(Mpt z)3]), tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H -1,2,4-triazolato]iridium(III) (abbreviation: [Ir(iPrptz-3 b) Organometallic iridium complexes with a 4H-triazole skeleton, such as 3), and tris [3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazol- Zolato]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]) Organometallic iridium complexes with fac-tris[1-(2,6-diisopropyl phenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviation: [Ir (iPrpmi)3]), tris[3-(2,6-dimethylphenyl)-7-methylimide Dazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: [Ir(dmp and organometallic iridium complexes having an imidazole skeleton, such as impt-Me)3). 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 Firpic, bis{2-[3',5'-bis(trifluoromethyl)fluorene] Phenyl]pyridinato-N,C 2’}Iridium(III) picolinate (abbreviation: [Ir( CF3ppy)2(pic)]), bis[2-(4',6'-difluorophenyl)pyri[ Ginat-N,C 2’ ]Iridium(III) acetylacetonate (abbreviation: FIraca c) Organometallic iridates with phenylpyridine derivatives having electron-withdrawing groups as ligands These are compounds that exhibit blue phosphorescence, with wavelengths from 440 nm to It is a compound that has an emission spectrum peak at 520 nm.

[0055] Also, tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)3]), tris(4-t-butyl-6-phenylpyrimidinato)yl Ir(tBuppm)3), (acetylacetonato)bis(Ir(tBuppm)3) (6-methyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mp pm)2(acac)]), (acetylacetonato)bis(6-tert-butyl-4- Phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)2(ac ac)]), (acetylacetonato)bis[6-(2-norbornyl)-4-phenylpiperidinyl] [Ir(nbppm)2(acac)]), (acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenyl [Pyrimidinato]iridium(III) (abbreviation: [Ir(mpmppm)2(acac)] ), (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(II I) (abbreviation: [Ir(dppm)2(acac)]) Organic metal iridium complexes and (acetylacetonato)bis(3,5-dimethyl-2-phenyl) Rupirazinato)iridium(III) (abbreviation: [Ir(mppr-Me)2(acac) ]), (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyridine) Dinato)iridium(III) (abbreviation: [Ir(mppr-iPr)2(acac)]) Organometallic iridium complexes with pyrazine skeletons such as tris(2-phenylpyridinium) Nat-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 (I II) Acetylacetonate (abbreviation: [Ir(bzq)2(acac)]), tris(benzyl) Tribenzo[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) acetylacetone Pyridine skeleton-containing compounds such as setonate (abbreviation: [Ir(pq)2(acac)]) In addition to organometallic iridium complexes, tris(acetylacetonato)(monophenanthroline)tetrahydrogen Rare earth metals such as rubium(III) (abbreviated as [Tb(acac)3(Phen)]) These are mainly compounds that exhibit green phosphorescence, with wavelengths from 500 nm to The emission spectrum peaks at 600 nm. Iridium complexes are particularly preferred because they are remarkably excellent in reliability and luminous efficiency.

[0056] Also, (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinyl] Nato]iridium(III) (abbreviation: [Ir(5mdppm)2(dibm)]), bis [4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridine Ir(III) (abbreviation: [Ir(5mdppm)2(dpm)]), bis[4,6-di( Naphthalen-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) Organogold compounds with pyrimidine skeletons, such as [Ir(d1npm)2(dpm)] iridium complexes of the genus acetylacetonatobis(2,3,5-triphenylpyrazine) Iridium(III) (abbreviation: [Ir(tppr)2(acac)]), bis(2, 3,5-triphenylpyrazinate)(dipivaloylmethanato)iridium(III)(abbreviation Name: [Ir(tppr)2(dpm)]), (acetylacetonato)bis[2,3-bis (4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: [Ir(Fd pq)2(acac)]), and organometallic iridium complexes with pyrazine skeletons such as Tris(1-phenylisoquinolinato-N,C 2’ ) Iridium(III) (abbreviation: [Ir (piq)3]), bis(1-phenylisoquinolinato-N,C 2’ ) Iridium (II I) Pyridyl acetylacetonate (abbreviation: [Ir(piq)2(acac)]) In addition to organometallic iridium complexes with iridium skeletons, 2,3,7,8,12,13,17,18 -octaethyl-21H,23H-porphyrin platinum(II) (abbreviation: PtOEP) Platinum complexes such as tris(1,3-diphenyl-1,3-propanedionato) (monophenyl Anthroline) europium(III) (abbreviation: [Eu(DBM)3(Phen)]), Tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthate) (Troline) europium(III) (abbreviation: [Eu(TTA)3(Phen)]) These are compounds that exhibit red phosphorescence and are Its emission spectrum peaks at 0 nm to 700 nm. It also has a pyrazine skeleton. The organometallic iridium complex can emit red light with good chromaticity.

[0057] In addition to the phosphorescent compounds described above, known phosphorescent light-emitting materials may be selected and used. stomach.

[0058] TADF materials include fullerene and its derivatives, acridine and its derivatives, and eosin. Derivatives of magnesium (Mg), zinc (Zn), cadmium, etc. can also be used. (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (P d) and the like. Examples of the metal-containing porphyrin include: For example, the protoporphyrin-tin fluoride complex (SnF2(Pro to IX), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), Hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), Copropor Phyllin tetramethyl ester-tin fluoride complex (SnF2(Copro III-4M e)), octaethylporphyrin-tin fluoride complex (SnF2(OEP)), ethiop Porphyrin-tin fluoride complex (SnF2(Etio I)), octaethylporphyrin -platinum chloride complex (PtCl2OEP) and the like.

[0059] [ka]

[0060] In addition, 2-(biphenyl-4-yl)-4,6-bis(12-phenyl)-4-phenyl-4-methyl-4-phenyl ... (phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine ( Abbreviation: PIC-TRZ) and 9-(4,6-diphenyl-1,3,5-triazine-2- yl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCzT zn), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-3-yl] 4,6-diphenyl-1,3,5-triazine (abbreviated as '4,6-diphenyl-1,3,5-triazine- ...') Name: 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-diphenyl Methyl-9H-acridin-10-yl)-9H-xanthen-9-one (Acr XTN), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl] Sulfone (abbreviation: DMAC-DPS), 10-phenyl-10H,10'H-spiro[a π electrons of clidin-9,9'-anthracen]-10'-one (abbreviation: ACRSA), etc. Heterocyclic compounds having either or both of a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring are also used. The heterocyclic compound may be a π-electron rich heteroaromatic ring or a π-electron deficient heteroaromatic ring. Since it has an aromatic ring, it has high electron transporting properties and hole transporting properties, which is preferable. Among the skeletons with a toe-shaped heteroaromatic ring, pyridine skeleton, diazine skeleton (pyrimidine skeleton, pyridine skeleton) The arazine skeleton, pyridazine skeleton, and triazine skeleton are preferred because they are stable and reliable. In particular, benzofuropyrimidine skeleton, benzothienopyrimidine skeleton, benzofuropyrimidine skeleton, The benzothienopyrazine and benzothienopyrazine skeletons are preferred because they have high acceptor properties and good reliability. In addition, among the skeletons having a π-electron-rich heteroaromatic ring, acridine skeleton, phenoxy The thiophene skeleton, the phenothiazine skeleton, the furan skeleton, the thiophene skeleton, and the pyrrole skeleton are It is preferable that the polymer has at least one of the above skeletons because it is stable and reliable. The orchid skeleton is a dibenzofuran skeleton, and the thiophene skeleton is a dibenzothiophene skeleton. The pyrrole skeleton is preferably an indole skeleton, a carbazole skeleton, or the like. skeleton, indolocarbazole skeleton, bicarbazole skeleton, 3-(9-phenyl-9H-carbazole) A π-electron-rich type (carbazol-3-yl)-9H-carbazole skeleton is particularly preferred. A substance in which a heteroaromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded is called a π-electron-rich heteroaromatic ring. The electron donating property of the π-electron deficient heteroaromatic ring and the electron accepting property of the π-electron deficient heteroaromatic ring are both strong, and the S1 and T1 levels Since the energy difference between the two positions is small, thermally activated delayed fluorescence can be obtained efficiently. It is preferable that an electron-withdrawing group such as a cyano group is bonded instead of the π-electron-deficient heteroaromatic ring. In addition, the π-electron-rich skeleton may be an aromatic amine skeleton, a phenyl skeleton, or the like. Examples of the π-electron deficient skeleton include a xanthene skeleton and a nadine skeleton. Thioxanthene dioxide skeleton, oxadiazole skeleton, triazole skeleton, imidazo borane skeleton, anthraquinone skeleton, boron-containing skeletons such as phenylborane and boranthrene, benzophenone skeleton, Aromatic or heteroaromatic rings containing nitrile or cyano groups such as benzonitrile or cyanobenzene aromatic ring, carbonyl skeleton such as benzophenone, phosphine oxide skeleton, sulfone skeleton, etc. In this way, π-electron deficient heteroaromatic rings and π-electron rich heteroaromatic rings can be used. A π-electron deficient skeleton and a π-electron rich skeleton may be used in place of at least one of the rings. can.

[0061] [ka]

[0062] TADF materials have a small difference between the S1 and T1 levels, and triple intersystem crossing occurs due to reverse intersystem crossing. The function of converting energy from first excitation energy to singlet excitation energy Therefore, the triplet excitation energy can be converted to a single state by a small amount of thermal energy. It is possible to upconvert to doublet excited energy (reverse intersystem crossing), and efficiently convert the singlet excited state It is possible to generate triplet excitation energy and convert it into luminescence. .

[0063] In addition, exciplexes (exciplexes) that form excited states with two types of substances The difference between the S1 and T1 levels is extremely small, As a TADF material capable of converting triplet excitation energy into singlet excitation energy, It has all the functions.

[0064] As an index of the T1 level, the phosphorescence spectrum observed at low temperatures (for example, from 77 K to 10 K) As for TADF materials, the fluorescent light spectrum has a short wavelength tail. Draw a tangent line to the S1 level, and the energy of the wavelength of the extrapolated line is the S1 level. When a tangent line is drawn at the long side of the tail 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. Even more preferable.

[0065] In addition, when a TADF material is used as the luminescent center, the S1 level of the host material is It is preferable that the T1 level of the host material is higher than the T1 level of the TADF material. A level higher than 1 is preferred.

[0066] The host material of the light-emitting layer 113 may be a material having an electron transporting property or a material having a hole transporting property. Various carrier transport materials can be used, including the TADF materials described above.

[0067] Materials with hole transport properties include organic compounds with an amine skeleton or a π-electron-rich heteroaromatic ring skeleton. Organic compounds are preferred. For example, 4,4'-bis[N-(1-naphthyl)-N-phenylalanine] N,N'-bis(3-methylphenyl)-N,N'-biphenyl (abbreviation: NPB), -Diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4, 4'-Bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenylamino] ]biphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluorene-9 -yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenyl mBPAFLP, 4-phenyl 4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation : PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazo PCBBi1BP), 4-(1-naphthyl-3-yl)triphenylamine )-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation : PCBAN), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carboxylate) PCBNBB, 9,9-dimethyl -N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]phenyl ]fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl (9H-carbazol-3-yl)phenyl]spiro-9,9'-bifluorene-2 -amine (abbreviated as PCBASF), and compounds with aromatic amine skeletons such as 1,3-bis(2-methyl-2-propanol). bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazolyl) Biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenyl CzTP, 3,3'-bis(9-phenyl-9H-carbazo) Compounds with a carbazole skeleton, such as PCCP (abbreviated as PCCP), and 4,4',4'' -(Benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P -II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluorene-9-yl] phenyl]dibenzothiophene (abbreviation: DBTFLP-III), 4-[4-(9- (phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and compounds with thiophene skeletons such as 4,4',4' '-(Benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P- II), 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]fluor phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II) Among the above, compounds having an aromatic amine skeleton and carbazole Compounds with this structure have good reliability and high hole transport properties, which contribute to reducing the driving voltage. In addition, the organic compounds listed as examples of the second organic compound may also be used. You can be there.

[0068] Examples of materials having electron transport properties include bis(10-hydroxybenzo[h]quinolinol). Nat)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), bis[2-(2-benzothiazolyl) Metal complexes such as phenolatozinc(II) (abbreviation: ZnBTZ) and π-electron-deficient heteroaromatic complexes An organic compound having an aromatic ring skeleton is preferred. An organic compound having a π-electron-deficient heteroaromatic ring skeleton is preferred. Examples of compounds 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-oxa diazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1 ,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO 11), 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl- 1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophene-4 -yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm Heterocyclic compounds with polyazole skeletons such as 2-[3-(dibenzothiophene)-II] and (4-phenyl)dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDB q-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]di Benzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-( 9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxalate 4,6-bis[3-(phenanthrene-9-yl)phenyl]phenanthren-9-yl]phenanthren-9-yl ... phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-diphenyl)pyrimidine Diazolidinyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II) Heterocyclic compounds with an amine skeleton and 3,5-bis[3-(9H-carbazol-9-yl] )phenyl]pyridine (abbreviation: 35DCzPPy), 1,3,5-tri[3-(3-pyridinyl) Heterocyclization of pyridine skeletons such as [(phenyl)phenyl]benzene (abbreviation: TmPyPB) Among the above, heterocyclic compounds having a diazine skeleton and heterocyclic compounds having a pyridine skeleton are preferred. Heterocyclic compounds having the formula (I) are preferred because of their excellent reliability. Heterocyclic compounds with a pyrazine skeleton have high electron transport properties and contribute to reducing driving voltage. .

[0069] The TADF materials that can be used as host materials are listed above as TADF materials. When a TADF material is used as a host material, the TA The triplet excitation energy generated in the DF material is converted to singlet excitation energy by reverse intersystem crossing. The energy is then transferred to the luminescent center substance, thereby increasing the luminous efficiency of the light-emitting element. In this case, the TADF material acts as an energy donor and the luminescence center The material acts as an energy acceptor.

[0070] This is extremely effective when the luminescent center substance is a fluorescent substance. In order to obtain high luminous efficiency, the S1 level of the TADF material must be higher than the S1 level of the fluorescent material. The T1 level of the TADF material is preferably higher than the S1 level of the fluorescent material. Therefore, the T1 level of the TADF material is preferably higher than the T1 level of the fluorescent material. It is preferable that the level is higher.

[0071] In addition, T that exhibits emission that overlaps with the wavelength of the lowest energy absorption band of the fluorescent substance It is preferable to use an ADF material, which allows the TADF material to be converted into a fluorescent material. This is preferable because the transfer of excitation energy becomes smooth and light emission can be obtained efficiently.

[0072] In addition, singlet excitation energy is efficiently generated from triplet excitation energy by reverse intersystem crossing. For this to occur, it is preferable that carrier recombination occurs in the TADF material. The triplet excitation energy generated in the DF material is transferred to the triplet excitation energy of the fluorescent material. For this purpose, it is preferable that the fluorescent substance has a luminophore ( It is preferable that the compound has a protecting group around the π bond (the skeleton that causes light emission). A substituent having no carbon atoms is preferred, and a saturated hydrocarbon is preferred, specifically a hydrocarbon having 3 to 10 carbon atoms. The alkyl groups listed below, substituted or unsubstituted cycloalkyl groups with 3 to 10 carbon atoms, A trialkylsilyl group having 3 to 10 protecting groups is preferred, and a group having a plurality of protecting groups is more preferred. Substituents without π bonds have poor carrier transport function, and therefore, The distance between the TADF material and the luminophores of the fluorescent material can be reduced without significantly affecting carrier recombination. Here, the luminophore is the molecule that causes light emission in a fluorescent substance. The luminophore preferably has a skeleton with a π bond and contains an aromatic ring. Preferably, the aromatic ring has a condensed aromatic ring or a condensed heteroaromatic ring. Examples of the heteroaromatic ring include a phenanthrene skeleton, a stilbene skeleton, an acridone skeleton, and a phenanthren skeleton. Examples of the hydroxyazine skeleton include naphthalene skeleton and anthracene skeleton. skeleton, fluorene skeleton, chrysene skeleton, triphenylene skeleton, tetracene skeleton, pyrene skeleton perylene skeleton, coumarin skeleton, quinacridone skeleton, naphthobisbenzofuran skeleton Fluorescent materials that emit light with high fluorescence quantum yields are preferred.

[0073] When a fluorescent substance is used as the luminescent center substance, the host material is preferably a compound having an anthracene skeleton. A material having an anthracene skeleton is preferably used as a host material for a fluorescent material. When used as a phosphor, it is possible to realize a light-emitting layer having good luminous efficiency and durability. As a material having an anthracene skeleton to be used as a support material, a diphenylanthracene skeleton is used. Because substances with a 9,10-diphenylanthracene skeleton are chemically stable, In addition, when the host material has a carbazole skeleton, the hole injection / transport property is high. However, a benzocarbazole skeleton in which a benzene ring is further condensed to a carbazole is preferred. When it contains a saccharin, the HOMO is shallower than that of carbazole by about 0.1 eV, making it easier for holes to enter. In particular, when the host material contains a dibenzocarbazole skeleton, The HOMO is about 0.1 eV shallower than that of rubazole, making it easier for holes to enter. It is also suitable because it has excellent transportability and high heat resistance. Among these, 9,10-diphenylanthracene skeleton and carbazole skeleton (and It is a substance that simultaneously has a benzocarbazole skeleton or a dibenzocarbazole skeleton. From the viewpoint of the hole injection and transport properties, a benzofluorene skeleton was used instead of a carbazole skeleton. A fluorene skeleton or a dibenzofluorene skeleton may also be used. Examples of such substances include 9-fluorene, Phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazo PCzPA, 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9 H-Carbazole (abbreviation: PCPN), 9-[4-(10-phenyl-9-anthracene 7-[4-(10-phenyl)phenyl]-9H-carbazole (abbreviation: CzPA), -9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgD BCzPA), 6-[3-(9,10-diphenyl-2-anthryl)phenyl]-benzophenone Zo[b]naphtho[1,2-d]furan (abbreviation: 2mBnfPPA), 9-phenyl-10 -{4-(9-phenyl-9H-fluoren-9-yl)biphenyl-4'-yl}an Thracene (abbreviation: FLPPA), 9-(1-naphthyl)-10-[4-(2-naphthyl) phenyl]anthracene (abbreviation: αN-βNPAnth), etc. In particular, CzP A, cgDBCzPA, 2mBnfPPA, and PCzPA show very good properties. This is the preferred choice.

[0074] The host material (fifth organic compound) may be a material in which multiple types of substances are mixed, When a mixed host material is used, a material having an electron transporting property and a material having a hole transporting property are mixed. It is preferable to mix a material having an electron transporting property and a material having a hole transporting property. By mixing, the transport properties of the light-emitting layer 113 can be easily adjusted, and the recombination region The hole transporting material and the electron transporting material can be easily controlled. The weight ratio of the content of the material having hole transport properties to the material having electron transport properties is 1:19 to 19. When the mixed host material is a fifth organic compound, its HOMO The level is regarded as the level of a material having hole transport properties.

[0075] A phosphorescent material can be used as part of the mixed material. When a fluorescent substance is used as the luminescent center, the luminescent substance is excited with excitation energy. It can be used as an energy donor that provides

[0076] Furthermore, these mixed materials may form an exciplex. The exciplex is formed to emit light that overlaps with the wavelength of the lowest energy absorption band of By selecting such a combination, energy transfer becomes smooth and light emission can be obtained efficiently. In addition, the use of this configuration is also preferable because the driving voltage is reduced.

[0077] At least one of the materials forming the exciplex may be a phosphorescent material. By doing so, triplet excitation energy is efficiently converted to singlet excitation energy by reverse intersystem crossing. can be converted to

[0078] As a combination of materials that efficiently form exciplexes, HO It is preferable that the MO level is equal to or higher than the HOMO level of the material having electron transport properties. When the LUMO level of the material having electron transport properties is higher than the LUMO level of the material having electron transport properties, It is preferable that the LUMO level and the HOMO level of the material are determined by cyclic voltammetry. From the electrochemical properties (reduction potential and oxidation potential) of the material measured by CV measurement It can be derived.

[0079] The formation of an exciplex is determined by, for example, the emission spectrum of a material having hole transport properties, the emission spectrum of a material having electron transport properties, The emission spectrum of the material having the above structure and the emission spectrum of the mixed film of these materials are shown in Fig. In comparison, the emission spectrum of the mixed film is shifted to longer wavelengths than the emission spectra of each material ( This can be confirmed by observing the phenomenon of a new peak on the long wavelength side. Alternatively, transient photoluminescence (PL) of materials with hole transport properties and electron transport properties can be observed. The transient PL of the materials with the same properties and the transient PL of the mixed film of these materials were compared. The transient PL lifetime of the film has a longer-lived component than the transient PL lifetime of each material, or a delayed component. This can be confirmed by observing the difference in transient response, such as the percentage of In addition, the above-mentioned transient PL may be read as transient electroluminescence (EL). That is, the transient EL of a material with hole transport properties and the transient E of a material with electron transport properties are By comparing the transient EL of the L and the mixed films and observing the difference in the transient response, The formation of exciplexes can be confirmed.

[0080] A light-emitting device according to one embodiment of the present invention having the above structure has a long lifetime. It is possible to do so.

[0081] (Embodiment 2) Next, examples of the detailed structure and materials of the light-emitting device will be described. As described above, the light-emitting device is made up of a plurality of layers between a pair of electrodes, an anode 101 and a cathode 102. The EL layer 103 has a hole injection layer 104 formed of a ZnO layer. 111, a first hole transport layer 112-1, a second hole transport layer 112-2, a light emitting layer 113 and and an electron transport layer.

[0082] The other layers included in the EL layer 103 are not particularly limited, and may include a hole injection layer, a hole transport layer, and the like. layer, electron transport layer, electron injection layer, carrier blocking layer, exciton blocking layer, charge generation layer, etc. , various layer structures can be applied.

[0083] The anode 101 is made of a metal, alloy, or conductive compound having a large work function (specifically, 4.0 eV or more). It is preferable to form the film using a material such as a material containing fluorine, a compound ... Indium tin oxide (ITO), silicon or Indium oxide-tin oxide, indium oxide-zinc oxide, oxide containing silicon oxide Examples include indium oxide containing tungsten and zinc oxide (IWZO). These conductive metal oxide films are usually formed by sputtering, but they can also be formed by methods such as sol-gel deposition. As an example of the manufacturing method, indium oxide-zinc oxide Sputtering was performed using a target containing 1 to 20 wt% zinc oxide added to indium oxide. Also, there are methods for forming the film by the ring method. Indium oxide (IWZO) is a material that is made by mixing tungsten oxide with indium oxide at a ratio of 0.5 to 5. % by weight and zinc oxide 0.1-1 wt% by sputtering. Other materials include gold (Au), platinum (Pt), nickel (Ni), and titanium. W, chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co) , copper (Cu), palladium (Pd), or nitrides of metallic materials (e.g., titanium nitride), etc. Graphene can also be used. Representative materials for forming the electrode have been listed above. In one embodiment of the present invention, the hole injection layer 1 11, an organic compound having hole transport properties and a substance showing electron accepting properties to the organic compound Since a composite material containing the above is used, the electrode material can be selected regardless of the work function.

[0084] In this embodiment, the laminated structure of the EL layer 103 is shown in FIGS. As shown, the hole injection layer 111, the hole transport layer 112 (first hole transport layer 112-1, second hole transport layer 112-2) In addition to the hole transport layer 112-2), the light emitting layer 113, the electron transport layer 114, and the electron injection layer 115 1B, the hole injection layer 111, the first hole transport layer 11 2-1, the second hole transport layer 112-2, the light emitting layer 113, the electron transport layer 114, and the charge emitting layer Two types of structures having the raw layer 116 will be described. Regarding the materials constituting each layer The specific examples are shown below.

[0085] The hole injection layer 111, the hole transport layer 112 (first hole transport layer 112-1, second hole transport layer 112-2) and the light-emitting layer 113 have been described in detail in the first embodiment, so The following description is omitted. Please refer to the description in the first embodiment.

[0086] The electron transport layer 114 is provided between the light emitting layer 113 and the cathode 102. The organic compound 114 is formed by including an organic compound having an electron transport property. The compound may be an organic compound having an electron transporting property that can be used as the host material. Alternatively, the organic compounds listed above as being usable as the host material for the fluorescent emitting substance may be In addition, when the square root of the electric field strength [V / cm] is 600, Electron mobility is 1×10 -7 cm 2 / Vs or more 5×10 -5 cm 2 / Vs or less It is preferable to use a mixture of these.

[0087] Between the electron transport layer 114 and the cathode 102, an electron injection layer 115 containing lithium fluoride (Li Alkali such as iF, cesium fluoride (CsF), calcium fluoride (CaF2), etc. A layer containing a metal, an alkaline earth metal, or a compound thereof may be provided. 5 is a layer made of a substance having an electron transporting property, in which an alkali metal or alkaline earth metal or A material containing these compounds or an electride may also be used. For example, a substance in which a high concentration of electrons is added to a mixed oxide of calcium and aluminum is Examples include:

[0088] In addition, a charge generation layer 114 is formed between the electron transport layer 114 and the cathode 102 instead of the electron injection layer 115. The charge generation layer 116 may be formed by applying a potential. 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. The charge generation layer 116 includes at least a P-type layer 117. The hole injection layer 111 may be formed using the composite material mentioned above as a material that can be used to form the hole injection layer 111. It is preferable that the P-type layer 117 is formed of the above-mentioned material constituting the composite material. The P-type layer 1 may be formed by laminating a film containing an acceptor material and a film containing a hole transport material. By applying a potential to the cathode 102, electrons are transported to the electron transport layer 114. Holes are injected and the light-emitting device operates.

[0089] The charge generation layer 116 includes an electron relay layer 118 and an electron injection buffer layer 119 in addition to the P-type layer 117. Preferably, one or both of layers 119 are provided.

[0090] The electron relay layer 118 contains at least a substance having electron transport properties, and the electron injection buffer layer 1 The electrons are transferred smoothly by preventing the interaction between the P-type layer 117 and the P-type layer 119. The LUMO level of the substance having electron transport properties contained in the relay layer 118 is The LUMO level of the electron-accepting material in the electron transport layer 114 is It is preferable that the LUMO level of the electron relay layer 118 is between the LUMO level of the material contained in the layer. The specific energy level of the LUMO level in the electron transport material used in It is preferable that the potential is set to −5.0 eV or more, and more preferably to −5.0 eV or more and −3.0 eV or less. The electron relay layer 118 may be made of a phthalocyanine-based material having electron transport properties. It is preferred to use a metal complex having a metal-oxygen bond and an aromatic ligand.

[0091] The electron injection buffer layer 119 contains an alkali metal, an alkaline earth metal, a rare earth metal, and These compounds (alkali metal compounds (oxides such as lithium oxide, halides, lithium carbonate) Alkaline earth metal compounds (including carbonates such as titanium and cesium carbonate), alkaline earth metal compounds (oxides, halogens compounds of rare earth metals (including oxides, halides, carbonates) or compounds of rare earth metals (including oxides, halides, carbonates) It is possible to use a material with high electron injection properties, such as SiO 2 .

[0092] The electron injection buffer layer 119 contains a material having an electron transporting property and an electron donating material. When formed, the electron donor material may be an alkali metal, an alkaline earth metal, a rare earth metal, Metals and their compounds (alkali metal compounds (oxides such as lithium oxide, halogens oxides, carbonates such as lithium carbonate and cesium carbonate), alkaline earth metal compounds (oxides compounds of rare earth metals (including oxides, halides, carbonates) or rare earth metal compounds (including oxides, halides , including carbonates), as well as tetrathianaphthacene (abbreviated as TTN), nickelocene, deca Organic compounds such as methylnickelocene can also be used. The material is the same as that of the electron transport layer 114 described above. It is possible.

[0093] The material for forming the cathode 102 is gold, which has a small work function (specifically, 3.8 eV or less). Metals, alloys, electrically conductive compounds, and mixtures thereof can be used. Specific examples of such cathode materials include alkali metals such as lithium (Li) and cesium (Cs). , and elements such as magnesium (Mg), calcium (Ca), and strontium (Sr) Elements belonging to Group 1 or 2 of the periodic table and alloys containing these elements (MgAg, AlL i), europium (Eu), ytterbium (Yb), and other rare earth metals, and However, an electron injection layer may be provided between the cathode 102 and the electron transport layer. By providing this, regardless of the magnitude of the work function, Al, Ag, ITO, silicon or oxide Various conductive materials such as silicon dioxide-containing indium oxide-tin oxide can be used as the cathode 102. You can be there. These conductive materials can be applied by dry methods such as vacuum deposition and sputtering, inkjet printing, It is possible to form the film using a spin coating method, etc. Also, it is possible to form the film using a wet sol-gel method. Alternatively, the metal layer may be formed by a wet method using a paste of a metal material.

[0094] The EL layer 103 can be formed by various methods, including dry and wet methods. For example, vacuum deposition, gravure printing, offset printing, screen printing, etc. A printing method, an ink jet method, a spin coating method, or the like may also be used.

[0095] Furthermore, the above-mentioned electrodes or layers may be formed using different film formation methods.

[0096] The structure of the layer provided between the anode 101 and the cathode 102 is not limited to the above. However, the proximity of the light-emitting region to the metals used in the electrodes and carrier injection layer In order to suppress quenching caused by the hole It is preferable to provide a light-emitting region where the electrons recombine with the cathode.

[0097] Furthermore, recombination in the hole transport layer or electron transport layer in contact with the light-emitting layer 113, particularly in the light-emitting layer 113 The carrier transport layer close to the region suppresses energy transfer from excitons generated in the light-emitting layer. Therefore, the band gap is determined by the luminescent material that constitutes the luminescent layer or the luminescent material contained in the luminescent layer. It is preferable that the material be made of a substance having a band gap larger than the band gap of the material. I wish.

[0098] Next, we developed a light-emitting device (a stacked element, a tandem element) that has a structure in which multiple light-emitting units are stacked. The embodiment of the light-emitting device (also referred to as a "light-emitting device") will be described with reference to FIG. A light-emitting device has multiple light-emitting units between the electrode and the cathode. The EL layer 103 has a structure similar to that of the EL layer 103 shown in FIG. 1(A1) or (A2). That is, the light-emitting device shown in FIG. 1C is a light-emitting device having a plurality of light-emitting units. The light-emitting device shown in FIG. 1(A1), (A2), or (B) has one light-emitting unit. It can be said that the light emitting device has

[0099] In FIG. 1C, a first light-emitting unit 511 and a second light-emitting unit 512 are disposed between the anode 501 and the cathode 502. The second light-emitting unit 512 is stacked, and the first light-emitting unit 511 and the second light-emitting unit A charge generating layer 513 is provided between the anode 501 and the cathode 502. These correspond to the anode 101 and the cathode 102 in Fig. 1(A1) and (A2), respectively. The same as mentioned in the explanation of A1) and (A2) can be applied. The first light-emitting unit 511 and the second light-emitting unit 512 may have the same configuration or different configurations. It's okay to have one.

[0100] When a voltage is applied between the anode 501 and the cathode 502, the charge generating layer 513 generates a light emitting The electron-injecting unit has the function of injecting electrons into one light-emitting unit and holes into the other light-emitting unit. In 1(C), when a voltage is applied so that the anode potential is higher than the cathode potential, In this case, the charge generating layer 513 injects electrons into the first light-emitting unit 511 and Any material capable of injecting holes into the gate 512 may be used.

[0101] The charge generation layer 513 is 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 has the properties of carrier injection, carrier transport, and the like. It has excellent electrical properties, making it possible to achieve low voltage and low current driving. When the anode side of the unit is in contact with the charge generating layer 513, the charge generating layer 513 is the light emitting unit. Since it can also function as a hole injection layer for the light-emitting unit, the light-emitting unit does not need to have a hole injection layer. Both are good.

[0102] In addition, when the electron injection buffer layer 119 is provided in the charge generation layer 513, the electron injection buffer Since the electron injection layer 119 plays the role of an electron injection layer in the light-emitting unit on the anode side, the light-emitting layer The unit does not necessarily need to have an electron injection layer.

[0103] Although the light-emitting device having two light-emitting units has been described in FIG. 1C, the light-emitting device having three or more light-emitting units may be used. The same can be applied to a light-emitting device in which the above light-emitting units are stacked. As in the light-emitting device according to the present embodiment, a plurality of light-emitting units are electrically connected between a pair of electrodes. By separating the layers with the generation layer 513, high brightness light emission is possible while keeping the current density low. This allows for an even longer-life element. The device can be realized.

[0104] In addition, by making the light-emitting color of each light-emitting unit different, the light-emitting device as a whole The desired color of light can be obtained. For example, a light-emitting device having two light-emitting units can be used. In this case, the first light-emitting unit emits red and green light, and the second light-emitting unit emits blue light. By doing so, it is possible to obtain a light emitting device that emits white light as a whole. Furthermore, as a configuration of a light emitting device in which three or more light emitting units are stacked, for example, a first The light-emitting unit has a first blue light-emitting layer and a second yellow or yellow-green light-emitting layer. a second light-emitting unit having a blue light-emitting layer; and a third light-emitting unit having a red light-emitting layer. The tandem device may be a light-emitting device as described above. Similarly, white light can be obtained.

[0105] In addition, the EL layer 103, the first light-emitting unit 511, the second light-emitting unit 512, and Each layer such as the charge generating layer and the electrodes can be formed by, for example, a vapor deposition method (including a vacuum deposition method), a droplet discharge method (including an ink jet method), or the like. It can be formed by using methods such as ink jet printing, coating, and gravure printing. They can be used in a variety of applications, including low molecular weight materials, medium molecular weight materials (including oligomers and dendrimers), and or polymeric material.

[0106] (Embodiment 3) In this embodiment, light emission using the light-emitting device described in the first and second embodiments is The device will now be described.

[0107] In this embodiment, a light-emitting device described in Embodiments 1 and 2 is used to manufacture a The light-emitting device will be described with reference to FIG. 2. Note that FIG. 2(A) shows the light-emitting device. 2(B) is a cross-sectional view taken along lines AB and CD in FIG. 2(A). The device includes a drive circuit section (source) shown by a dotted line that controls the light emission of the light emitting device. The pixel section 602 includes a gate line driving circuit section (gate line driving circuit) 601, a pixel section 602, and a driving circuit section (gate line driving circuit) 603. Further, 604 is a sealing substrate, 605 is a sealing material, and the inside surrounded by the sealing material 605 has become space 607.

[0108] The lead wiring 608 is connected to the source line driver circuit 601 and the gate line driver circuit 603. The wiring is for transmitting signals, and the FPC (flexible printed circuit board) is the external input terminal. Video signal, clock signal, start signal, reset signal, etc. from the input circuit 609 Although only the FPC is shown here, this FPC has a printed wiring board. The light emitting device in this specification may be a light emitting device. This includes not only the device itself but also the state in which an FPC or PWB is attached to it. do.

[0109] Next, the cross-sectional structure will be described with reference to FIG. A source line driver circuit 601 and a pixel portion are formed. , one pixel in the pixel section 602 is shown.

[0110] The element substrate 610 may be a substrate made of glass, quartz, organic resin, metal, alloy, semiconductor, or the like. FRP (Fiber Reinforced Plastics), PVF (Polyvinyl It is made using a plastic substrate made of, for example, fluoride, polyester, or acrylic. That's fine.

[0111] The structure of the transistors used in the pixels and driver circuits is not particularly limited. The transistor may be a top-type transistor or a staggered type transistor. The transistor may be a gate type transistor or a bottom gate type transistor. The semiconductor material is not particularly limited, and examples thereof include silicon, germanium, silicon carbide, and nitride. Gallium or the like can be used. Alternatively, in-type metal oxides such as In-Ga-Zn-based metal oxides can be used. An oxide semiconductor containing at least one of tungsten, gallium, and zinc may be used.

[0112] The crystallinity of the semiconductor material used in the transistor is not particularly limited. A semiconductor having crystallinity (microcrystalline semiconductor, polycrystalline semiconductor, single crystal semiconductor, or a semiconductor having a partially crystalline region) When a semiconductor having crystallinity is used, the transistor This is preferable because it can suppress deterioration of the star characteristics.

[0113] Here, in addition to the transistors provided in the pixels and the driver circuits, It is preferable to use an oxide semiconductor for a semiconductor device such as a transistor. In particular, it is preferable to use an oxide semiconductor having a wider band gap than silicon. By using an oxide semiconductor with a wider band gap than silicon, the off-state of the transistor can be This can reduce the current in the

[0114] The oxide semiconductor preferably contains at least indium (In) or zinc (Zn). In addition, In-M-Zn oxides (where M is Al, Ti, Ga, Ge, Y, Zr, Sn, It is preferable that the oxide semiconductor contains an oxide represented by the formula (metal such as La, Ce or Hf). More preferable.

[0115] Here, an oxide semiconductor that can be used in one embodiment of the present invention will be described below. .

[0116] Oxide semiconductors are divided into single-crystal oxide semiconductors and other non-single-crystal oxide semiconductors. As a non-single-crystal oxide semiconductor, for example, CAAC-OS (c-axis alignable oxide semiconductor) gned crystalline oxide semiconductor), polycrystalline nc-OS (nano crystalline oxide semiconductor) semiconductor), pseudo-amorphous oxide semiconductor (a-like OS) amorphous-like oxide semiconductor), and amorphous oxide semiconductor Conductors, etc.

[0117] CAAC-OS has a c-axis orientation and multiple nanocrystals are connected in the ab-plane direction. The crystal structure has distortion. The distortion is the area where multiple nanocrystals are connected. In the region, the lattice arrangement is changed between a region with a uniform lattice arrangement and another region with a uniform lattice arrangement. Indicates the point where the direction is changing.

[0118] Nanocrystals are basically hexagonal, but they are not limited to regular hexagonal shapes and may be non-regular hexagonal. The distortion may also have lattice arrangements such as pentagons and heptagons. In CAAC-OS, clear grain boundaries (grain boundaries) are observed even near the strain. It is difficult to confirm the presence of grains due to distortion of the lattice arrangement. This is because the CAAC-OS has a crystalline structure in the ab-plane direction. The oxygen atoms are not densely packed, and the bond distance between atoms is shortened by the substitution of metal elements. This is because distortion can be tolerated by changing the frequency.

[0119] In addition, the CAAC-OS has a layer containing indium and oxygen (hereinafter referred to as an In layer) and an element A layered crystal structure in which layers containing M, zinc, and oxygen (hereinafter referred to as (M, Zn) layers) are stacked. It is noted that indium and element M tend to have a layered structure. It is possible, and when the element M in the (M,Zn) layer is replaced with indium, (In,M,Zn) Also, when indium in the In layer is replaced with element M, (In,M ) layer.

[0120] CAAC-OS is an oxide semiconductor with high crystallinity. Since it is difficult to identify grain boundaries, the decrease in electron mobility caused by grain boundaries is unlikely to occur. In addition, the crystallinity of oxide semiconductors is degraded by the inclusion of impurities and the generation of defects. Therefore, CAAC-OS should be free from impurities and defects (oxygen vacancies (V O :oxygen Therefore, CAA Oxide semiconductors containing C-OS have stable physical properties. The oxide semiconductor has high heat resistance and high reliability.

[0121] nc-OS is a material that can be used in microscopic areas (e.g., areas between 1 nm and 10 nm, especially areas between 1 nm and 3 nm). The nc-OS has periodic atomic arrangement in the nanometer range (nm or less). There is no regularity in the crystal orientation between the crystals. Therefore, no orientation is observed throughout the film. Therefore, depending on the analysis method, nc-OS may be distinguished from a-like OS or amorphous oxide semiconductor. It may be difficult to distinguish between the two.

[0122] Note that indium, gallium, and zinc are oxide semiconductors. The IGZO nanocrystals mentioned above are stable. In particular, IGZO tends to have difficulty growing crystals in the atmosphere. , small crystals (e.g., crystals of several mm or several cm) are more likely to be formed than large crystals (here, crystals of several mm or several cm). For example, the nanocrystals mentioned above may be structurally more stable.

[0123] The a-like OS is an oxide semiconductor with a structure between the nc-OS and amorphous oxide semiconductor. Conductive. A-like OS has voids or low density regions. The ke-OS has lower crystallinity than the nc-OS and CAAC-OS.

[0124] Oxide semiconductors have a variety of structures, each of which has different characteristics. Oxide semiconductors include amorphous oxide semiconductors, polycrystalline oxide semiconductors, a-like OS, and nc The compound may have two or more of -OS and CAAC-OS.

[0125] In addition to the oxide semiconductors mentioned above, Cloud-Aligned Computing (CAC) osite)-OS may also be used.

[0126] CAC-OS is a material that has a conductive function in some parts and an insulating function in other parts. The material as a whole functions as a semiconductor. When used in the semiconductor layer of The insulating function is the function of preventing the flow of electrons, which act as carriers. The function of switching is achieved by making the insulating function and the switching function ( On / Off function) can be added to CAC-OS. By separating the functions of each, the functions of both can be maximized.

[0127] The CAC-OS also has a conductive region and an insulating region. The insulating region has the above-mentioned insulating function. In some cases, the conductive and insulating regions are separated at the nanoparticle level. The conductive and insulating regions may be unevenly distributed in the material. may be observed as a cloud-like cluster with the periphery blurred.

[0128] In addition, in CAC-OS, the conductive region and the insulating region are each 0.5 nm or more. When the particles are dispersed in the material in a size of 10 nm or less, preferably 0.5 nm to 3 nm, There is a match.

[0129] In addition, the CAC-OS is composed of components having different band gaps. For example, CAC-OS consists of a wide-gap component originating from the insulating region and a conductive component originating from the conductive region. In this configuration, the carrier is When the carriers flow, they mainly flow in the narrow gap component. The component with a gap acts complementary to the component with a wide gap, Carriers flow into the wide-gap component in conjunction with the wide-gap component. When the CAC-OS is used in a channel forming region of a transistor, In the on state, a high current driving force, i.e., a large on-current, and a high field-effect mobility are obtained. It is possible.

[0130] That is, CAC-OS is a matrix composite. , or metal matrix composite It can also be called.

[0131] By using the above-mentioned oxide semiconductor material for the semiconductor layer, fluctuations in electrical characteristics are suppressed and reliability is improved. This makes it possible to realize highly reliable transistors.

[0132] Furthermore, the transistor having the above-described semiconductor layer can be used as a transistor due to its low off-state current. It is possible to retain the charge stored in the capacitor for a long period of time through such a transistor. By applying a transistor to each pixel, the gradation of the image displayed in each display area can be maintained while driving It is also possible to shut down the circuit. As a result, electronic devices with extremely low power consumption can be realized. It can be realized.

[0133] For stabilizing the characteristics of the transistor, it is preferable to provide an underlayer film. Inorganic films such as silicon oxide film, silicon nitride film, silicon oxynitride film, and silicon nitride oxide film The insulating film can be formed as a single layer or a laminated layer. CVD (Chemical Vapor Deposition) method (Plasma CVD method) , thermal CVD method, MOCVD (Metal Organic CVD) method, etc.), ALD ( Formed using Atomic Layer Deposition (ALD), coating, printing, etc. It should be noted that the undercoat film need not be provided if it is not necessary.

[0134] The FET 623 indicates one of the transistors formed in the driving circuit section 601. The drive circuit is made up 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. However, this is not necessarily required, and the drive circuit can be formed externally rather than on the substrate. .

[0135] The pixel section 602 includes a switching FET 611, a current control FET 612 and its driver. The pixel is formed by a plurality of pixels including an anode 613 electrically connected to the drain. However, the present invention is not limited to this, and the pixel section may be a combination of three or more FETs and a capacitance element.

[0136] An insulator 614 is formed to cover the end of the anode 613. It can be formed by using a photosensitive acrylic.

[0137] In order to improve the coverage of the EL layer and the like to be formed later, the insulating material 614 is For example, the material of the insulator 614 is When a positive photosensitive acrylic is used, the radius of curvature (0. It is preferable that the insulating material 614 has a curved surface with a thickness of 2 μm to 3 μm. Either a negative photosensitive resin or a positive photosensitive resin can be used.

[0138] An EL layer 616 and a cathode 617 are formed on the anode 613. It is desirable to use a material with a large work function for the anode 613. For example, ITO film, or silicon-containing indium tin oxide film, 2 to 20 wt% oxide Zinc-containing indium oxide film, titanium nitride film, chromium film, tungsten film, Zn film, Pt In addition to single layer films such as titanium nitride films, laminated films with aluminum as the main component, titanium nitride films, A three-layer structure of a titanium nitride film, a film mainly composed of aluminum, and the like can be used. Furthermore, the multilayer structure provides low resistance as wiring and good ohmic contact. The cathode can then be made to function as an anode.

[0139] The EL layer 616 can be formed by a deposition method using a deposition mask, an inkjet method, or a spin coating method. The EL layer 616 is formed by various methods such as those described in the first and second embodiments. Other materials that make up the EL layer 616 include: It may be a low molecular weight compound or a high molecular weight compound (including an oligomer or dendrimer). .

[0140] Furthermore, the material used for the cathode 617 formed on the EL layer 616 is a material having a small work function. Materials with low resistance (Al, Mg, Li, Ca) or their alloys or compounds (MgAg, MgIn, It is preferable to use AlLi, etc. When light is transmitted through the cathode 617, a thin metal film and a transparent conductive film (I TO, indium oxide containing 2-20 wt% zinc oxide, indium tin containing silicon It is preferable to use a laminate of an oxide, zinc oxide (ZnO, etc.).

[0141] The anode 613, the EL layer 616, and the cathode 617 form a light-emitting device. The light-emitting device is the light-emitting device described in the first and second embodiments. The pixel portion is formed with a plurality of light-emitting devices. The device includes the light-emitting device described in the first and second embodiments and other components. The light emitting device may include both a light emitting device having a light emitting element and a light emitting device having a light emitting element.

[0142] Furthermore, the sealing substrate 604 is bonded to the element substrate 610 with a sealing material 605. A light-emitting device is placed in a space 607 surrounded by a sub-substrate 610, a sealing substrate 604, and a sealing material 605. The space 607 is filled with a filler material. In some cases, the gas is filled with an inert gas (nitrogen, argon, etc.), and in other cases, it is filled with a sealing material. Deterioration due to moisture can be prevented by forming a recess in the sealing substrate and providing a desiccant there. This is a preferable configuration because it can suppress the above.

[0143] It is preferable to use epoxy resin or glass frit for the sealing material 605. It is desirable that these materials be as impermeable to moisture and oxygen as possible. Materials used for the sealing substrate 604 include glass substrates, quartz substrates, and FRP (Fiber Reinforced Plastics). reinforced plastics), PVF (polyvinyl fluoride), polyester A plastic substrate made of polyethylene or acrylic can be used.

[0144] Although not shown in Figure 2, a protective film may be provided on the cathode. The insulating film may be formed. In addition, a protective film may be formed to cover the exposed portion of the sealing material 605. The protective film may be formed on the surfaces and sides of the pair of substrates, the sealing layer, the insulating layer, It can be provided to cover the exposed side surfaces of the above.

[0145] The protective film can be made of a material that is difficult for impurities such as water to permeate. It is possible to effectively prevent impurities such as these from diffusing from the outside to the inside.

[0146] The materials that make up the protective film include oxides, nitrides, fluorides, sulfides, ternary compounds, and metals. Alternatively, polymers and the like can be used, for example, aluminum oxide, hafnium oxide, hafnium Lanthanum 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 hafnium, aluminum nitride, hafnium nitride, silicon nitride, tantalum nitride, titanium nitride, niobium nitride, molybdenum nitride, zirconium nitride, or gallium nitride, etc. Materials, nitrides containing titanium and aluminum, oxides containing titanium and aluminum , oxides containing aluminum and zinc, sulfides containing manganese and zinc, cerium and sulfides containing erbium and strontium, oxides containing erbium and aluminum, yttrium Materials containing oxides containing lithium and zirconium can be used.

[0147] The protective film can be formed using a film formation method that provides good step coverage. One such method is atomic layer deposition (ALD). The ALD method can be used to form protective materials. It is preferable to use it for films. By using the ALD method, it is possible to eliminate cracks, pinholes, etc. It is possible to form a protective film with reduced defects or with a uniform thickness. Damage to the processed member when forming the protective film can be reduced.

[0148] For example, by forming a protective film using the ALD method, it is possible to fabricate a surface with complex irregularities or a surface with a touch panel. A uniform protective film with few defects can be formed on the top, sides and back of the panel. .

[0149] As described above, the light-emitting devices described in the first and second embodiments were used to manufacture the A light emitting device having such a structure can be obtained.

[0150] The light emitting device of the present embodiment is the same as the light emitting device of the first and second embodiments. Since the semiconductor device is used, it is possible to obtain a light emitting device with excellent characteristics. The light emitting devices described in the first and second embodiments are light emitting devices with long lifetimes. Therefore, a light emitting device with good reliability can be obtained. 2. A light-emitting device using the light-emitting device described in 2. has good luminous efficiency, and therefore consumes little power. It may be an optical device.

[0151] In FIG. 3, a light-emitting device that emits white light is formed, and a colored layer (color filter) is provided. FIG. 3(A) shows an example of a full-color light-emitting device. an insulating film 1002, a gate insulating film 1003, gate electrodes 1006, 1007, 1008, The first interlayer insulating film 1020, the second interlayer insulating film 1021, the peripheral portion 1042, and the pixel portion 1040 , a driving circuit unit 1041, anodes 1024W, 1024R, 1024G of the light-emitting device, 24B, a partition wall 1025, an EL layer 1028, a cathode 1029 of a light-emitting device, and a sealing substrate 103 1, sealing material 1032, etc. are shown.

[0152] In addition, in FIG. 3(A), the colored layers (red colored layer 1034R, green colored layer 1034G, blue The colored layer 1034B is provided on a transparent substrate 1033. A transparent substrate 1 on which a colored layer and a black matrix are provided may be further provided. The colored layer and the black matrix are aligned and fixed to the substrate 1001. The dust 1035 is covered with an overcoat layer 1036. The light-emitting layer is where light does not pass through the colored layers and goes out, and the light passes through the colored layers of each color and goes out. The light that does not pass through the colored layer is white, and the light that passes through the colored layer is red, green, or blue. This allows images to be expressed using four color pixels.

[0153] In FIG. 3(B), the colored layers (red colored layer 1034R, green colored layer 1034G, blue colored layer An example in which a layer 1034B) is formed between the gate insulating film 1003 and the first interlayer insulating film 1020 As shown in the figure, the colored layer is provided between the substrate 1001 and the sealing substrate 1031. is also good.

[0154] In the light emitting device described above, light is taken in toward the substrate 1001 on which the FET is formed. The light emitting device has a bottom emission structure, but the light is taken in from the sealing substrate 1031 side. The light emitting device may have a top emission structure. A cross-sectional view of the light-emitting device is shown in FIG. 4. In this case, a substrate that does not transmit light is used as the substrate 1001. Until the connection electrode that connects the FET and the anode of the light-emitting device is fabricated, After that, a third interlayer insulating film 1037 is formed on the substrate 1031 in the same manner as in the case of the multi-emission light emitting device. The insulating film is formed to cover the electrode 1022. This insulating film may also serve as a planarizing layer. The interlayer insulating film 1037 may be formed using the same material as the second interlayer insulating film, or other known materials. It is possible.

[0155] The anodes 1024W, 1024R, 1024G, and 1024B of the light-emitting device are the anodes here. However, it may be formed as a cathode. In the case of an optical device, it is preferable that the anode is a reflective electrode. The EL layer 103 has the same structure as that described in the first and second embodiments, and In addition, the device structure is designed to produce white light emission.

[0156] In the top emission structure shown in Figure 4, the colored layers (red colored layer 1034R, green colored layer The sealing is performed by a sealing substrate 1031 provided with a blue color layer 1034G and a blue color layer 1034B. The sealing substrate 1031 has a black matrix disposed between the pixels. A coloring layer (red coloring layer 1034R, green coloring layer 1034G, The blue colored layer 1034B) and the black matrix are covered by the overcoat layer 1036. The sealing substrate 1031 may be covered. Note that a light-transmitting substrate is used. Although an example of full-color display using four colors, red, green, blue, and white, is shown here, there is no particular limitation. Alternatively, full color display may be performed using four colors of red, yellow, green, and blue, or three colors of red, green, and blue.

[0157] In a top-emission type light-emitting device, the microcavity structure can be suitably applied. The light-emitting device with a microcavity structure uses the anode as a reflective electrode and the cathode as a semi-transparent / semi-reflective electrode. At least one electrode is provided between the reflective electrode and the semi-transparent / semi-reflective electrode. It has an EL layer, and at least has a light-emitting layer that becomes a light-emitting region.

[0158] The reflectance of the reflective electrode for visible light is 40% to 100%, preferably 70% to 100%. %, and its resistivity is 1×10 -2 The film is assumed to be less than Ωcm. The semi-reflective electrode has a visible light reflectance of 20% to 80%, preferably 40% to 70%. , and its resistivity is 1×10 -2 It is assumed that the film has a resistance of Ωcm or less.

[0159] The light emitted from the light-emitting layer included in the EL layer is reflected by the reflective electrode and the semi-transparent and semi-reflective electrode. The sound is reflected and resonates.

[0160] The light-emitting device is made by changing the thickness of the transparent conductive film, the composite material, the carrier transport material, etc. By doing so, the optical distance between the reflective electrode and the semi-transmissive / semi-reflective electrode can be changed. This strengthens the light of the resonating wavelength between the reflective electrode and the semi-transparent and semi-reflective electrode, and It can attenuate light of wavelengths that are not

[0161] The light reflected by the reflective electrode and returned (first reflected light) is semi-transmitted from the light emitting layer. The light that directly enters the semi-reflective electrode (first incident light) interferes greatly with the reflective electrode. The optical distance of the light-emitting layer is (2n-1)λ / 4 (where n is a natural number greater than or equal to 1, and λ is the amplified It is preferable to adjust the optical distance to a wavelength of the first light. By matching the phase of the reflected light with the phase of the first incident light, the light emitted from the light-emitting layer can be further amplified. do.

[0162] In the above configuration, even if the EL layer has a plurality of light-emitting layers, a single light-emitting For example, it may be combined with the above-mentioned tandem light-emitting device configuration. In addition, multiple EL layers are provided in one light-emitting device with a charge generating layer sandwiched between them, and each EL The layer may be configured to have one or more light-emitting layers.

[0163] The microcavity structure makes it possible to enhance the front-direction emission intensity of specific wavelengths. This allows for lower power consumption. In the case of a light-emitting device that displays images using a single pixel, the yellow light emission not only improves brightness, but also Since a microcavity structure tailored to the wavelength of each color can be applied, it is possible to achieve light-emitting devices with excellent characteristics. It can be placed.

[0164] The light emitting device of the present embodiment is the same as the light emitting device of the first and second embodiments. Since the semiconductor device is used, it is possible to obtain a light emitting device with excellent characteristics. The light emitting devices described in the first and second embodiments are light emitting devices with long lifetimes. Therefore, a light emitting device with good reliability can be obtained. 2. A light-emitting device using the light-emitting device described in 2. has good luminous efficiency, and therefore consumes little power. It may be an optical device.

[0165] Up to this point, we have explained about active matrix light emitting devices, but from now on we will be talking about passive light emitting devices. A passive matrix light-emitting device will be described. 5A is a perspective view showing the light emitting device, and FIG. 5B) is a cross-sectional view of FIG. 5A cut along XY. In FIG. 5, on a substrate 951, An EL layer 955 is provided between the electrode 952 and the electrode 956. The ends of the electrode 952 are It is covered with an insulating layer 953. A partition wall layer 954 is provided on the insulating layer 953. The sidewalls of the partition layer 954 become thicker between one sidewall and the other sidewall as they approach the substrate surface. That is, the cross section of the partition wall layer 954 in the short side direction has a slope such that the gap between the partition walls becomes narrower. The bottom side (the side that faces the same direction as the surface direction of the insulating layer 953 and is in contact with the insulating layer 953) ) is the upper side (the side that faces in the same direction as the surface direction of the insulating layer 953 and does not come into contact with the insulating layer 953). In this way, by providing the partition layer 954, it is possible to prevent the light emitting device from being damaged by static electricity or the like. In addition, the present invention can also be applied to passive matrix light emitting devices. The light emitting device according to the first embodiment and the second embodiment is used, and the light emitting device has high reliability. A light-emitting device with low power consumption can be obtained.

[0166] The light emitting device described above is composed of a large number of minute light emitting devices arranged in a matrix. Since it is possible to control each of these, it can be suitably used as a display device for displaying images. It is a light-emitting device.

[0167] This embodiment mode can be freely combined with other embodiment modes.

[0168] (Fourth embodiment) In this embodiment, the light-emitting device according to any one of the first and second embodiments is used as a lighting device. An example of using the lighting device as an illumination device will be described with reference to FIG. 6. FIG. 6(B) is a top view of the lighting device, and FIG. 6(A) is a bottom view of the lighting device. ) is a cross-sectional view taken along line ef in FIG. 6(B).

[0169] The lighting device of this embodiment has an anode 4 on a light-transmitting substrate 400 serving as a support. The anode 401 corresponds to the anode 101 in the second embodiment. When light is extracted from the anode 401 side, the anode 401 is formed from a light-transmitting material.

[0170] A pad 412 for supplying a voltage to the cathode 404 is formed on the substrate 400 .

[0171] An EL layer 403 is formed on the anode 401. The EL layer 403 is the same as that in the first embodiment and the second embodiment. The configuration of the EL layer 103 in the second embodiment, or the light-emitting units 511 and 512 and the charge generation This corresponds to a configuration in which the layer 513 is combined. For details of these configurations, refer to the relevant description. I want to be done that.

[0172] A cathode 404 is formed to cover the EL layer 403. The cathode 404 is the same as the cathode 1 in the second embodiment. When light is extracted from the anode 401 side, the cathode 404 is made of a material with high reflectivity. The cathode 404 is connected to a pad 412, and a voltage is applied to the cathode 404. can be.

[0173] As described above, the light-emitting device having the anode 401, the EL layer 403, and the cathode 404 is The lighting device shown in FIG. 1 has a high luminous efficiency. Therefore, the lighting device in this embodiment can be a lighting device with low power consumption.

[0174] The substrate 400 on which the light emitting device having the above structure is formed is sealed with a sealing substrate 407. The lighting device is completed by fixing and sealing using sealing materials 405 and 406. Either 405 or 406 may be used. In addition, the inner sealing material 406 (FIG. 6(B) ) (not shown) can also be mixed with a desiccant, which can absorb moisture. This leads to improved reliability.

[0175] In addition, a part of the pad 412 and the anode 401 is provided so as to extend outside the sealing materials 405 and 406. By doing so, it can be used as an external input terminal. An IC chip 420 or the like may be provided.

[0176] As described above, the lighting device according to the present embodiment uses the EL element according to the first and second embodiments. The light-emitting device described above is used to provide a light-emitting device with good reliability even at high temperatures. In addition, a light-emitting device with low power consumption can be provided.

[0177] (Embodiment 5) In this embodiment, the light emitting device according to the first and second embodiments is used as a part thereof. An example of an electronic device including the light-emitting device according to the first embodiment and the second embodiment will be described. The device has a long life and is a light-emitting device with good reliability even at high temperatures. The electronic device described in this embodiment has an electronic device having a light emitting portion with good reliability at high temperatures. It is possible to make it into a device.

[0178] Examples of electronic devices to which the light-emitting device is applied include television sets (televisions, (also called television receivers), computer monitors, digital cameras, digital digital video cameras, digital photo frames, mobile phones (also known as mobile phones or mobile phone devices) (hereinafter referred to as "games"), portable game machines, personal digital assistants, sound reproduction devices, large game machines such as pachinko machines Specific examples of these electronic devices are listed below.

[0179] 7A shows an example of a television device. The television device includes a housing 710 A display unit 7103 is built into the housing 1. In this case, a stand 7105 is used to hold the housing The display unit 7103 can display images. The display portion 7103 is configured using the light-emitting device described in Embodiments 1 and 2. They are arranged in a matrix.

[0180] The television device can be operated using the operation switches on the housing 7101 or a separate remote control. This can be done by the operation key 7109 provided on the remote control operation device 7110. This allows you to control the channel and volume, and the image displayed on the display unit 7103 In addition, the remote control operation device 7110 can be operated. A display portion 7107 for displaying information output from the

[0181] The television device is assumed to be equipped with a receiver, modem, etc. It can receive television broadcasts and can also communicate by wire or wireless via a modem. By connecting to a network, you can send and receive data in one direction (sender to receiver) or two directions (sender to receiver). It is also possible to communicate information between the recipient and the receiver, or between receivers themselves.

[0182] FIG. 7(B1) shows a computer, which includes a main body 7201, a housing 7202, a display portion 7203, and a keyboard. keyboard 7204, external connection port 7205, pointing device 7206, etc. The computer may be configured to use the light-emitting devices described in the first and second embodiments. The liquid crystal display panels 7203 are manufactured by arranging them in a matrix. The computer may be in the form shown in FIG. 7(B2). The keyboard 7204 and the pointing device 7206 are replaced by a second display unit 7207. The second display portion 7210 is a touch panel type. The input display on the display unit 7210 is operated with a finger or a special pen. The second display portion 7210 can be used not only for input display but also for other displays. The display unit 7203 may also be a touch panel. The two screens are connected by a hinge, which can damage the screen when storing or transporting it. This also prevents problems such as breakage.

[0183] FIG. 7C shows an example of a mobile terminal. The mobile phone is built in a housing 7401. In addition to the display unit 7402, operation buttons 7403, an external connection port 7404, a speaker 740 5, a microphone 7406, etc. The mobile phone is the same as that of the first embodiment and the second embodiment. A display portion 7402 in which the light-emitting devices according to embodiment 2 are arranged in a matrix is ​​provided. are.

[0184] The mobile terminal shown in FIG. 7C allows users to input information by touching the display portion 7402 with a finger or the like. In this case, it is possible to make a call or create an email. Operations such as turning on / off the camera can be performed by touching the display portion 7402 with a finger or the like.

[0185] The screen of the display unit 7402 has three main modes. The first is a display mode that mainly displays images. The first mode is a display mode, and the second mode is an input mode that mainly inputs information such as characters. This is a display + input mode that combines two modes: display mode and input mode.

[0186] For example, when making a call or creating an email, the display unit 7402 is used to input characters. This is the main character input mode, and you can input characters displayed on the screen. It is preferable to display a keyboard or number buttons on most of the screen of the display portion 7402. I wish.

[0187] In addition, the mobile terminal may include a sensor for detecting tilt, such as a gyro or acceleration sensor. By providing a device, the orientation of the mobile terminal (portrait or landscape) can be determined and the screen display of the display portion 7402 can be displayed. The display can be switched automatically.

[0188] The screen mode can be switched by touching the display portion 7402 or by operating the housing 7401. This is done by operating the button 7403. Also, depending on the type of image displayed on the display unit 7402, For example, if the image signal to be displayed on the display unit is a video signal, If it is data, the display mode is switched to, and if it is text data, the input mode is switched to.

[0189] In the input mode, the optical sensor of the display unit 7402 detects a signal and displays it. If there is no input by touch operation on the part 7402 for a certain period of time, the screen mode is changed to the input mode. Alternatively, the display mode may be switched from the normal mode to the display mode.

[0190] The display portion 7402 can also function as an image sensor. By touching the device with your palm or fingers and capturing an image of your palm print or fingerprint, you can authenticate your identity. In addition, a backlight that emits near-infrared light to the display unit or a sensing light that emits near-infrared light By using a source, it is also possible to image finger veins, palm veins, etc.

[0191] Note that the structure described in this embodiment mode may be obtained by appropriately combining the structures described in any of Embodiment Modes 1 to 4. They can be used in combination.

[0192] As described above, the light emitting device according to the first and second embodiments can be applied to the light emitting apparatus. The range of applications is extremely wide, and this light-emitting device can be applied to electronic devices in a wide range of fields. By using the light-emitting devices according to the first and second embodiments, Therefore, it is possible to obtain highly reliable electronic equipment.

[0193] FIG. 8(A) is a schematic diagram showing an example of a cleaning robot.

[0194] The cleaning robot 5100 has a display 5101 on the top surface and multiple The camera 5102, the brush 5103, and the operation button 5104 are also shown. However, the underside of the cleaning robot 5100 is provided with tires, a suction port, etc. The robot 5100 also has an infrared sensor, an ultrasonic sensor, an acceleration sensor, a piezo sensor, It is equipped with various sensors such as a sensor, a light sensor, and a gyro sensor. 100 is equipped with wireless communication means.

[0195] The cleaning robot 5100 moves by itself, detects the dust 5120, and sucks it out from the suction port on the bottom. It can suck up dirt.

[0196] In addition, the cleaning robot 5100 analyzes the image captured by the camera 5102 and detects the wall, furniture, or It can detect obstacles such as steps. Image analysis can also detect obstacles such as wiring. If an object that may get tangled in the brush 5103 is detected, the rotation of the brush 5103 can be stopped. can.

[0197] The display 5101 can display the remaining battery level and the amount of dust sucked. The route traveled by the cleaning robot 5100 can be displayed on the display 5101. In addition, the display 5101 is a touch panel, and the operation button 5104 is It may be provided in the ray 5101.

[0198] The cleaning robot 5100 can communicate with a portable electronic device 5140 such as a smartphone. The images captured by the camera 5102 can be displayed on the portable electronic device 5140. Therefore, the owner of the Cleaning Robot 5100 can check the status of the room even when he is away from home. In addition, the display on the display 5101 can be displayed on a mobile electronic device such as a smartphone. You can also check it out at.

[0199] The light-emitting device according to one embodiment of the present invention can be used for the display 5101 .

[0200] The robot 2100 shown in FIG. 8(B) includes a computing device 2110, an illuminance sensor 2101, a microphone 2102, upper camera 2103, speaker 2104, display 2105, It is equipped with an internal camera 2106, an obstacle sensor 2107, and a movement mechanism 2108.

[0201] The microphone 2102 has a function of detecting the user's voice and environmental sounds. The speaker 2104 has a function of emitting sound. The device 2102 and the speaker 2104 can be used to communicate with the user. It is possible.

[0202] The display 2105 has the function of displaying various information. Any information desired by the user can be displayed on the display 2105. The display 2105 may be equipped with a touch panel. It may be an information terminal that can be charged by placing it in a fixed position on the robot 2100. and enables data transfer.

[0203] The upper camera 2103 and the lower camera 2106 are used to capture images of the surroundings of the robot 2100. The obstacle sensor 2107 detects the obstacles in the robot 210 by using the moving mechanism 2108. When moving forward, the robot can sense whether there are any obstacles in its path. 00 uses an upper camera 2103, a lower camera 2106, and an obstacle sensor 2107. The light-emitting device according to one embodiment of the present invention can recognize the surrounding environment and move safely. It can be used for the display 2105.

[0204] FIG. 8(C) is a diagram showing an example of a goggle-type display. For example, a housing 5000, a display unit 5001, a speaker 5003, an LED lamp 5004, Connection terminal 5006, sensor 5007 (force, displacement, position, velocity, acceleration, angular velocity, rotation speed, Distance, light, liquid, magnetism, temperature, chemicals, sound, time, hardness, electric field, current, voltage, power, radiation (including those that measure radiation, flow rate, humidity, gradient, vibration, odor, or infrared radiation), The device includes a microphone 5008, a display unit 5002, a support unit 5012, earphones 5013, and the like.

[0205] The light-emitting device of one embodiment of the present invention can be used for the display portion 5001 and the display portion 5002. .

[0206] FIG. 9 shows a configuration of the light-emitting device according to the first and second embodiments in an electric lighting device. This is an example of a desk lamp. The desk lamp shown in FIG. 9 is made up of a housing 2001 and a light source 2002. The lighting device described in Embodiment 3 may be used as the light source 2002.

[0207] FIG. 10 shows the light-emitting device according to the first and second embodiments installed in an indoor lighting device 3. 001. The light-emitting devices described in the first and second embodiments are Highly reliable light-emitting device at high temperatures, providing reliable lighting at high temperatures The light-emitting device according to the first and second embodiments can be a device. Since the area can be increased, it can be used as a large-area lighting device. The light emitting devices according to the first and second embodiments are thin, and therefore can be used for thin lighting. It can be used as a device.

[0208] The light emitting devices according to the first and second embodiments can be used for automobile windshields and windows. The present invention can also be implemented on a flash board. The light emitting device is used in an automobile windshield or dashboard. The display areas 5200 to 5203 are the light-emitting devices described in Embodiments 1 and 2. This is a display area provided using a device.

[0209] In this embodiment, the display area 5200 and the display area 5201 are provided on the windshield of a car. 1 and 2. In the light-emitting device described in the second embodiment, the anode and the cathode are made of light-transmitting electrodes. This allows the opposite side to be seen through, making it a so-called see-through light-emitting device. If the display is see-through, it can be installed on the windshield of a car. It can be installed without obstructing the view. When providing the above, organic transistors made of organic semiconductor materials or oxide semiconductors are used. A light-transmitting transistor such as a light-transmitting transistor may be used.

[0210] The display area 5202 is the display device described in Embodiments 1 and 2 provided in the pillar portion. The display device is equipped with an optical device. The display area 5202 is equipped with an imaging device mounted on the vehicle body. By projecting images from the steps, it is possible to compensate for the view obstructed by the pillars. Similarly, the display area 5203 provided on the dashboard is not blocked by the vehicle body. By projecting images from an imaging device installed outside the vehicle, the driver can see the blind spots. By projecting images to complement the invisible parts, safety can be improved. This allows the driver to check for safety more naturally and without any discomfort.

[0211] The display area 5203 displays various information such as navigation information, speedometer, tachometer, etc. By displaying various information, it is possible to provide various information. The display can be adjusted to suit the user's preferences. The display items and layout can be changed as needed. 5200 to 5202. Area 5203 can also be used as a lighting device.

[0212] 12(A) and (B) show a foldable mobile information terminal 5150. The foldable mobile information terminal 5150 includes a housing 5151, a display area 5152, and a bending portion 515 12(A) shows the mobile information terminal 5150 in an unfolded state. Figure 5B) shows the mobile information terminal in a folded state. The mobile information terminal 5150 has a large display area. Despite having a range of 5152, it is compact and highly portable when folded.

[0213] The display area 5152 can be folded in half by the bend 5153. 3 is composed of an expandable member and multiple support members, and when folding, The member is elongated, and the bent portion 5153 has a curvature radius of 2 mm or more, preferably 3 mm or more. It can be folded.

[0214] The display area 5152 is a touch panel (input / output) equipped with a touch sensor (input device). The light-emitting device of one embodiment of the present invention can be used in the display region 5152. Cut.

[0215] 13(A) to 13(C) show a foldable mobile information terminal 9310. 13(A) shows the mobile information terminal 9310 in an unfolded state. The mobile information terminal 9310 is shown in a state in which it is changing from one folded state to the other. FIG. 13C shows the portable information terminal 9310 in a folded state. The foldable design offers excellent portability and a seamless, large viewing area when unfolded. This provides excellent visibility of the display.

[0216] The display panel 9311 is supported by three housings 9315 connected by hinges 9313. The display panel 9311 is a touch panel equipped with a touch sensor (input device). The display panel 9311 may be a display panel (input / output device). The two housings 9315 are bent to open the mobile information terminal 9310. The light-emitting device of one embodiment of the present invention can be reversibly transformed from a folded state to a folded state. It can be used for the display panel 9311. [Example]

[0217] In this example, a light-emitting device 1 according to one embodiment of the present invention and a comparative light-emitting device 1 will be described. The structural formulas of the organic compounds used in Light-Emitting Device 1 and Comparative Light-Emitting Device 1 are shown below. vinegar.

[0218] [ka]

[0219] (Method for fabricating light-emitting device 1) First, indium tin oxide containing silicon oxide (ITSO) was sputtered onto a glass substrate. The anode 101 was formed by a film deposition method. The film thickness was 70 nm and the electrode area was 2 mm x 2 mm.

[0220] Next, as a pretreatment for forming a light-emitting device on the substrate, the substrate surface was washed with water. After baking at 00°C for 1 hour, UV ozone treatment was performed for 370 seconds.

[0221] Then, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside pressure has been reduced to about 100 Pa. After vacuum baking at 170°C for 30 minutes in the heating chamber of the device, the substrate is left for about 30 minutes. Allow to cool.

[0222] Next, the substrate on which the anode 101 is formed is placed in a vacuum chamber so that the surface on which the anode 101 is formed faces downward. The substrate was fixed to a substrate holder installed in the vacuum evaporation device, and evaporation was performed on the anode 101 using resistance heating. By this method, N-(1,1'-biphenyl-4-yl)-N- [4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl -9H-fluorene-2-amine (abbreviation: PCBBiF) and ALD-MP001Q ( (Material serial number: 1S20170124) in a weight ratio of 1:0.1 (=PCBBiF:ALD-MP001Q) and hole injection were performed by co-evaporating 10 nm A layer 111 was formed.

[0223] Next, PCBBiF was deposited on the hole injection layer 111 to form a first hole transport layer 112-1. After that, a second hole transport layer 112-2 was formed by vapor deposition of a compound represented by the above structural formula (ii). N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino- p-Terphenyl (abbreviation: DBfBB1TP) was evaporated to a thickness of 10 nm to form a hole transport layer. The second hole transport layer 112-2 also functions as an electron blocking layer. do.

[0224] Next, 7-[4-(10-phenyl-9-anthryl)-2-(2-methyl-2-phenyl)-1,3-diol represented by the above structural formula (iii) )phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA) and 3,10-bis[N-(9-phenyl-9H-carbazole) represented by the following structural formula (iv)] -2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzof Ran (abbreviation: 3,10PCA2Nbf(IV)-02) in a weight ratio of 1:0.015 (= 25nm co-evaporation to give cgDBCzPA:3,10PCA2Nbf(IV)-02 The light-emitting layer 113 was formed by deposition.

[0225] Then, on the light-emitting layer 113, 2-[3'-(dibenzothiophene)-2-(3-methyl-2-benzophenone]-1-yl]-2-(3-methyl-2-benzophenone)-1-yl]-2-(dibenzothiophene ... [phenyl-4-yl]biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2m After vapor deposition of DBTBPDBq-II) to a thickness of 15 nm, 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline An electron transport layer 114 is formed by depositing nitriloline (abbreviation: NBPhen) to a thickness of 10 nm. Formed.

[0226] After forming the electron transport layer 114, lithium fluoride (LiF) was evaporated to a thickness of 1 nm. The electron injection layer 115 is formed by depositing aluminum to a thickness of 200 nm. The cathode 102 was formed by vapor deposition, and the light-emitting device 1 of this example was fabricated.

[0227] (Method for producing comparative light-emitting device 1) The comparative light-emitting device 1 is a light-emitting device in which cgDBCzPA in the light-emitting device 1 is replaced with a compound represented by the above structural formula (vii ) represented by 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthraquinone The light-emitting device was fabricated in the same manner as in light-emitting device 1, except that the ZnSe layer was changed to αN-βNPAnth.

[0228] The device structures of Light-Emitting Device 1 and Comparative Light-Emitting Device 1 are summarized in the table below.

[0229] [Table 1]

[0230] Here, the HOMO levels of the organic compounds used in this example are summarized in a table below.

[0231] [Table 2]

[0232] This light-emitting device was placed in a glove box with a nitrogen atmosphere, and the light-emitting device was exposed to the atmosphere. The process of sealing with a glass substrate to prevent exposure (sealing material is applied around the element and sealed) After performing UV treatment and heat treatment at 80°C for 1 hour, the initial characteristics and The reliability and reliability of the device were measured at room temperature.

[0233] The luminance vs. current density characteristics of the light-emitting device 1 are shown in Figure 14, the current efficiency vs. luminance characteristics in Figure 15, and the luminance Figure 16 shows the voltage characteristics, Figure 17 shows the current-voltage characteristics, and Figure 18 shows the power efficiency-brightness characteristics. The external quantum efficiency-luminance characteristics are shown in Figure 19, and the emission spectrum is shown in Figure 20. 1000cd / m 2 The main characteristics of the area are shown in Table 3.

[0234] [Table 3]

[0235] 14 to 20 and Table 3, the light-emitting device 1 according to one embodiment of the present invention and the comparative light-emitting device Device 1 was found to be a blue light-emitting device with good properties.

[0236] In addition, at a high temperature of 85°C, the current density was 50 mA / cm 2 The brightness versus drive time when The graph showing the change is shown in FIG. 21(A). As shown in FIG. 21(A), the light-emitting device 1 The decay follows a nearly single exponential function, whereas the comparative light-emitting device 1 does not. It is also clear that the rate of deterioration is high.

[0237] On the other hand, Figure 21(B) shows the current density at room temperature of 50 mA / cm 2 When the drive time is 1 is a graph showing the change in luminance at room temperature. Both the temperature and humidity decrease almost exponentially, and the slope of the degradation curve is small. Furthermore, at room temperature, the comparative light-emitting device 1 deteriorated more rapidly than the light-emitting device 1. It was found that the degradation was small, which was the opposite of that observed at a high temperature of 85°C.

[0238] The host material in the light-emitting layer of the light-emitting device 1, which is a light-emitting device according to one embodiment of the present invention, is cg A second hole transport layer, DBCzPA (HOMO level -5.69 eV), in contact with the light-emitting layer. The material is DBfBB1TP (HOMO level -5.50 eV), so the difference is 0.19 On the other hand, in the comparative light-emitting device 1, the host material in the light-emitting layer is αN-βNPAn th (HOMO level -5.85 eV), the HO The difference in MO level is 0.35 eV.

[0239] Here, we compared the temperature acceleration coefficients of each light-emitting device. The time elapsed until the brightness has deteriorated to 90% of the initial value (LT90(RT)) is measured at 85°C. The time elapsed until the luminance has deteriorated to 90% of the initial luminance (LT90 (85 deg. Therefore, the smaller the temperature acceleration coefficient, the higher the operating temperature. 21(A) and (B) show that the influence of temperature on deterioration is small when The LT90 (RT) and LT90 (85 deg.) of each light-emitting device were read. The results and temperature acceleration factors are shown below.

[0240] [Table 4]

[0241] When DBfBB1TP having a shallow HOMO level is used for the second hole transport layer 112-2, HO The light-emitting device 1 using cgDBCzPA, a host material with a shallower MO level, has a higher HOM Compared with comparative light-emitting device 1 using αN-βNPAnth, a host material with a deep O level The temperature acceleration coefficient is small, and the device is less susceptible to temperature effects even in high-temperature drive tests. In this way, the difference in HOMO level between the material used in the second hole transport layer and the host material is small. The results show that the lower the temperature, the less susceptible the device is to temperature-induced degradation when operated at high temperatures.

[0242] The HOMO level of the host material and the H of the hole transport material used in the hole transport layer in contact with the light-emitting layer In comparative light-emitting device 1, where the difference in OMO levels is greater than 0.24 eV, the degradation at high temperatures is observed. The degree of degradation was very large, and the shape of the degradation curve changed, so it was possible to distinguish between different mechanisms. On the other hand, the difference is less than 0.24 eV. The light-emitting device 1 below did not suffer from such problems and showed good results. The HOMO level of the host material and the hole transport material used in the hole transport layer in contact with the light-emitting layer It is more preferable that the difference in HOMO levels is 0.20 eV or less. [Example]

[0243] In this example, a light-emitting device 2 according to one embodiment of the present invention and a comparative light-emitting device 2 will be described. The structural formulas of the organic compounds used in Light-Emitting Device 2 and Comparative Light-Emitting Device 2 are shown below. vinegar.

[0244] [ka]

[0245] (Method for fabricating light-emitting device 2) First, indium tin oxide containing silicon oxide (ITSO) was sputtered onto a glass substrate. The anode 101 was formed by a film deposition method. The film thickness was 70 nm and the electrode area was 2 mm x 2 mm.

[0246] Next, as a pretreatment for forming a light-emitting device on the substrate, the substrate surface was washed with water. After baking at 00°C for 1 hour, UV ozone treatment was performed for 370 seconds.

[0247] Then, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside pressure has been reduced to about 100 Pa. After vacuum baking at 170°C for 30 minutes in the heating chamber of the device, the substrate is left for about 30 minutes. Allow to cool.

[0248] Next, the substrate on which the anode 101 is formed is placed in a vacuum chamber so that the surface on which the anode 101 is formed faces downward. The substrate was fixed to a substrate holder installed in the vacuum evaporation device, and evaporation was performed on the anode 101 using resistance heating. By this method, N,N-bis(4-biphenyl)-6-phenyl-2-(4-phenyl-2-phenyl)-2-phenyl-4-phenyl-2-phenyl-1-propanol represented by the above structural formula (viii) was obtained. Phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf) , ALD-MP001Q (Breakdown Workshop Co., Ltd., Material serial number: 1S20170124 ) in a weight ratio of 1:0.1 (=BBABnf:ALD-MP001Q), A hole injection layer 111 was formed to a thickness of 10 nm by co-evaporation.

[0249] Next, BBABnf was deposited on the hole injection layer 111 to a thickness of 30 nm to form a hole transport layer. The hole transport layer 112 also functions as an electron blocking layer.

[0250] Next, 7-[4-(10-phenyl-9-anthryl)-2-(2-methyl-2-phenyl)-1,3-diol represented by the above structural formula (iii) )phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA) and 3,10-bis[N-(9-phenyl-9H-carbazole) represented by the following structural formula (iv)] -2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzof Ran (abbreviation: 3,10PCA2Nbf(IV)-02) in a weight ratio of 1:0.015 (= 25nm co-evaporation to give cgDBCzPA:3,10PCA2Nbf(IV)-02 The light-emitting layer 113 was formed by deposition.

[0251] Then, on the light-emitting layer 113, 2-[3'-(dibenzothiophene)-2-(3-methyl-2-benzophenone]-1-yl]-2-(3-methyl-2-benzophenone)-1-yl]-2-(dibenzothiophene ... [phenyl-4-yl]biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2m After vapor deposition of DBTBPDBq-II) to a thickness of 15 nm, 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline An electron transport layer 114 is formed by depositing nitriloline (abbreviation: NBPhen) to a thickness of 10 nm. Formed.

[0252] After forming the electron transport layer 114, lithium fluoride (LiF) was evaporated to a thickness of 1 nm. The electron injection layer 115 is formed by depositing aluminum to a thickness of 200 nm. The cathode 102 was formed by vapor deposition, and the light-emitting device 2 of this example was fabricated.

[0253] (Method for producing comparative light-emitting device 2) The comparative light-emitting device 2 is a light-emitting device in which cgDBCzPA in the light-emitting device 2 is replaced with a compound represented by the above structural formula (vii ) represented by 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthraquinone The light-emitting device was fabricated in the same manner as light-emitting device 2, except that the ZnSe layer was changed to αN-βNPAnth.

[0254] The device structures of the light-emitting device 2 and the comparative light-emitting device 2 are summarized in the table below.

[0255] [Table 5]

[0256] Here, the HOMO levels of the organic compounds used in this example are summarized in a table below.

[0257] [Table 6]

[0258] This light-emitting device was placed in a glove box with a nitrogen atmosphere, and the light-emitting device was exposed to the atmosphere. The process of sealing with a glass substrate to prevent exposure (sealing material is applied around the element and sealed) After performing UV treatment and heat treatment at 80°C for 1 hour, the initial characteristics and The reliability and reliability of the device were measured at room temperature.

[0259] The luminance vs. current density characteristics of light-emitting device 2 are shown in Figure 22, the current efficiency vs. luminance characteristics in Figure 23, and the luminance Figure 24 shows the voltage characteristics, Figure 25 shows the current-voltage characteristics, and Figure 26 shows the power efficiency-brightness characteristics. The external quantum efficiency-luminance characteristics are shown in Figure 27, and the emission spectrum is shown in Figure 28. 1000cd / m 2 The main characteristics of the area are shown in Table 7.

[0260] [Table 7]

[0261] 22 to 28 and Table 7, the light-emitting device 2 according to one embodiment of the present invention and the comparative light-emitting device Device 2 was found to be a blue light-emitting device with good properties.

[0262] In addition, at a high temperature of 85°C, the current density was 50 mA / cm 2 The brightness versus drive time when The graph showing the change is shown in Figure 29(A). As shown in Figure 29(A), the light-emitting device 2 The decay follows a nearly single exponential function, whereas the comparative light-emitting device 2 does not. It is also clear that the rate of deterioration is high.

[0263] On the other hand, Figure 29(B) shows the current density at room temperature of 50 mA / cm 2 When the drive time is 1 is a graph showing the change in luminance at room temperature. Both the temperature and humidity levels decrease almost exponentially, and the slope of the degradation curve is small. Furthermore, at room temperature, the comparative light-emitting device 2 deteriorated more rapidly than the light-emitting device 2. It was found that the degradation was small, which was the opposite of that observed at a high temperature of 85°C.

[0264] Here, the host material in the light-emitting layer of the light-emitting device 2, which is a light-emitting device according to one embodiment of the present invention, The material is cgDBCzPA (HOMO level -5.69 eV), and the second positive electrode in contact with the light-emitting layer The material of the hole transport layer is BBABnf (HOMO level -5.56 eV), so the difference is 0. On the other hand, in the comparative light-emitting device 2, the host material in the light-emitting layer is αN-βNP. Anth (HOMO level -5.85 eV), the HOM with the second hole transport layer The difference in the O level is 0.29 eV.

[0265] Here, we compared the temperature acceleration coefficients of each light-emitting device. The time elapsed until the brightness has deteriorated to 90% of the initial value (LT90(RT)) is measured at 85°C. The time elapsed until the luminance has deteriorated to 90% of the initial luminance (LT90 (85 deg. Therefore, the smaller the temperature acceleration coefficient, the higher the operating temperature. 29(A) and (B) show that the influence of temperature on deterioration is small when The LT90 (RT) and LT90 (85 deg.) of each light-emitting device were read. The results and temperature acceleration factors are shown below.

[0266] [Table 8]

[0267] In this example, BBA, which has a slightly deeper HOMO level than DBfBB1TP used in Example 1, was used. Bnf was used as the material for the hole transport layer in contact with the light-emitting layer. The difference between the MO level and the HOMO level of the material in the hole transport layer in contact with the light-emitting layer is small. In Example 2, the difference was small and the light-emitting device 2 showed better results in the high-temperature driving test. The difference in the temperature acceleration coefficient between the light-emitting device 2 and the comparative light-emitting device 2 was The difference in temperature coefficient between the light-emitting device 1 and the comparative light-emitting device 1 is smaller than that in the comparative light-emitting device 1.

[0268] In this way, the host material and the hole transport material HO used in the hole transport layer in contact with the light-emitting layer In comparative light-emitting device 2, where the difference in MO levels is greater than 0.24 eV, degradation at high temperatures is observed. The degree of progression was very large, and the shape of the degradation curve changed, suggesting a different mechanism. On the other hand, it was found that the difference was less than 0.24 eV. The light-emitting device 2 did not suffer from such problems and showed good results. The difference in the HOMO level of the light-emitting device 2 is 0.13 eV, which is the same as that of the light-emitting device in Example 1. The difference in the HOMO level between the two is 0.19 eV, but the operating life at 85°C is shorter. Therefore, in one embodiment of the present invention, a host material and an emitting layer are The difference in HOMO levels of the hole transport materials used in the adjacent hole transport layers is 0.16 eV or less. It is more preferable to do so. [Example]

[0269] In this example, a light-emitting device 3 and a light-emitting device 4 according to one embodiment of the present invention will be described. The structural formulae of the organic compounds used in light-emitting device 3 and light-emitting device 4 are shown below.

[0270] [ka]

[0271] (Method for fabricating light-emitting device 3) First, indium tin oxide containing silicon oxide (ITSO) was sputtered onto a glass substrate. The anode 101 was formed by a film deposition method. The film thickness was 70 nm and the electrode area was 2 mm x 2 mm.

[0272] Next, as a pretreatment for forming a light-emitting device on the substrate, the substrate surface was washed with water. After baking at 00°C for 1 hour, UV ozone treatment was performed for 370 seconds.

[0273] Then, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside pressure has been reduced to about 100 Pa. After vacuum baking at 170°C for 30 minutes in the heating chamber of the device, the substrate is left for about 30 minutes. Allow to cool.

[0274] Next, the substrate on which the anode 101 is formed is placed in a vacuum chamber so that the surface on which the anode 101 is formed faces downward. The substrate was fixed to a substrate holder installed in the vacuum evaporation device, and evaporation was performed on the anode 101 using resistance heating. By this method, N,N-bis(4-biphenyl)-6-phenyl-2-(4-phenyl-2-phenyl)-2-phenyl-4-phenyl-2-phenyl-1-propanol represented by the above structural formula (viii) was obtained. Phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf) , ALD-MP001Q (Breakdown Workshop Co., Ltd., Material serial number: 1S20170124 ) in a weight ratio of 1:0.1 (=BBABnf:ALD-MP001Q), A hole injection layer 111 was formed to a thickness of 10 nm by co-evaporation.

[0275] Next, BBABnf was deposited on the hole injection layer 111 to form a first hole transport layer 112-1. After that, a second hole transport layer 112-2 having a thickness of 100 nm was deposited by vapor deposition. 3,3'-(naphthalene-1,4-diyl)bis(9-phenyl-9H-carbamoyl) PCzN2) was evaporated to a thickness of 10 nm to form a hole transport layer 112. The second hole transport layer 112-2 also functions as an electron blocking layer.

[0276] Next, 7-[4-(10-phenyl-9-anthryl)-2-(2-methyl-2-phenyl)-1,3-diol represented by the above structural formula (iii) )phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA) and 3,10-bis[N-(9-phenyl-9H-carbazole) represented by the following structural formula (iv)] -2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzof Ran (abbreviation: 3,10PCA2Nbf(IV)-02) in a weight ratio of 1:0.015 (= 25nm co-evaporation to give cgDBCzPA:3,10PCA2Nbf(IV)-02 The light-emitting layer 113 was formed by deposition.

[0277] Then, on the light-emitting layer 113, 2-[3'-(dibenzothiophene)-2-(3-methyl-2-benzophenone]-1-yl]-2-(3-methyl-2-benzophenone)-1-yl]-2-(dibenzothiophene ... [phenyl-4-yl]biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2m After vapor deposition of DBTBPDBq-II) to a thickness of 15 nm, 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline An electron transport layer 114 is formed by depositing nitriloline (abbreviation: NBPhen) to a thickness of 10 nm. Formed.

[0278] After forming the electron transport layer 114, lithium fluoride (LiF) was evaporated to a thickness of 1 nm. The electron injection layer 115 is formed by depositing aluminum to a thickness of 200 nm. The cathode 102 was formed by vapor deposition, and the light-emitting device 3 of this example was fabricated.

[0279] (Method for fabricating light-emitting device 4) The light-emitting device 4 is a light-emitting device 3 in which cgDBCzPA is replaced with a compound represented by the above structural formula (vii). 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: αN-βNPAnth) was used, and the other components were fabricated in the same manner as in light-emitting device 3.

[0280] The device structures of light-emitting device 3 and light-emitting device 4 are summarized in the table below.

[0281] [Table 9]

[0282] Here, the HOMO levels of the organic compounds used in this example are summarized in a table below.

[0283] [Table 10]

[0284] This light-emitting device was placed in a glove box with a nitrogen atmosphere, and the light-emitting device was exposed to the atmosphere. The process of sealing with a glass substrate to prevent exposure (sealing material is applied around the element and sealed) After performing UV treatment and heat treatment at 80°C for 1 hour, the initial characteristics and The reliability and reliability of the device were measured at room temperature.

[0285] The luminance vs. current density characteristics of light-emitting device 3 and light-emitting device 4 are shown in Figure 30, and the current efficiency vs. luminance The characteristics are shown in Figure 31, the brightness-voltage characteristics in Figure 32, the current-voltage characteristics in Figure 33, and the power efficiency- The luminance characteristics are shown in Figure 34, the external quantum efficiency-luminance characteristics are shown in Figure 35, and the emission spectrum is shown in Figure 36. In addition, the luminance of light-emitting device 3 and light-emitting device 4 is 1000 cd / m 2 Major in the vicinity The characteristics are shown in Table 11.

[0286] [Table 11]

[0287] 30 to 36 and Table 11, the light-emitting device 3 and the light-emitting device Device 4 was found to be a blue-emitting device with good properties.

[0288] In addition, at a high temperature of 85°C, the current density was 50 mA / cm 2 The brightness versus drive time when The graph showing the change is shown in Figure 37(A). As shown in Figure 37(A), the light-emitting device 3 For both light-emitting devices, the brightness of the light-emitting devices decays over time approximately according to a single exponential function. It can be seen that this is the case.

[0289] On the other hand, Figure 37(B) shows the current density at room temperature of 50 mA / cm 2 When the drive time is 10 is a graph showing the change in luminance with increasing room temperature. In both cases, the luminance of the light-emitting device decreased with time approximately monoexponentially, and It can be seen that the slope of the deterioration curve is small.

[0290] Here, the host material in the light-emitting layer of the light-emitting device 3, which is a light-emitting device according to one embodiment of the present invention, The material is cgDBCzPA (HOMO level -5.69 eV), and the hole transport layer in contact with the light-emitting layer The material of the layer is PCzN2 (HOMO level -5.71 eV), so the difference is 0.02 eV In addition, the light-emitting device 4 has a host material in the light-emitting layer of αN-βNPAnth(H Since the HOMO level is -5.85 eV, the difference in the HOMO level with the second hole transport layer is The value is 0.14 eV.

[0291] Here, we compared the temperature acceleration coefficients of each light-emitting device. The time elapsed until the brightness has deteriorated to 90% of the initial value (LT90(RT)) is measured at 85°C. The time elapsed until the luminance has deteriorated to 90% of the initial luminance (LT90 (85 deg. Therefore, the smaller the temperature acceleration coefficient, the higher the operating temperature. This shows that the effect of temperature degradation is small when The LT90 (RT) and LT90 (85 deg.) of each light-emitting device were read. The results and temperature acceleration factors are shown below.

[0292] [Table 12]

[0293] In this example, PC having a deep HOMO level was used as the material for the hole transport layer in contact with the light emitting layer. The difference between the HOMO level of the host material and that of PCzN2 is small. It's getting smaller by the minute.

[0294] Comparative light-emitting device 1 of Example 1, comparative light-emitting device 2 of Example 2, and the light-emitting device of this Example. When comparing Device 4, the host material is the same in both devices, but the material of the hole transport layer in contact with the light-emitting layer is H. The deeper the OMO level, i.e., the greater the difference between the HOMO level of the host material and the material of the hole transport layer. The smaller the difference between the HOMO level and the It was found that the operating life can be extended.

[0295] In this way, the host material and the hole transport material HO used in the hole transport layer in contact with the light-emitting layer The light-emitting devices 3 and 4, in which the difference in MO levels is 0.24 eV or less, are driven at high temperatures. The light-emitting device has a small temperature acceleration coefficient during operation and a good high-temperature operating life. The difference in the HOMO levels between the light-emitting devices 3 and 4 was Although the difference in the HOMO levels is smaller than 0.20 eV in the light-emitting device 1 of Example 1, It was found that the operating life at 85°C was improved.

[0296] <Reference example> In this reference example, the HOMO level and LUMO level of the organic compound used in each example were calculated using the following method. We will explain about this.

[0297] HOMO and LUMO levels are calculated based on cyclic voltammetry (CV) measurements. It is possible.

[0298] The measurement device used was an electrochemical analyzer (manufactured by BAS Co., Ltd., model number: ALS model). The solution used in the CV measurements was dehydrated dimethyl ether. Dimethylformamide (DMF) (Aldrich Corporation, 99.8%, Catalog No. 227 05-6) was used, and the supporting electrolyte was tetra-n-butylammonium perchlorate (nB u4NClO4) (Tokyo Chemical Industry Co., Ltd., Catalog No.: T0836) at 100 mmol / The measurement target is dissolved in a solution to a concentration of 2 mmol / L. The working electrode was a platinum electrode (PT, manufactured by BAS Co., Ltd.). E platinum electrode), and as an auxiliary electrode, a platinum electrode (B.A.S. Co., Ltd., VC-3 P The counter electrode (5 cm) was used as the reference electrode, and the Ag / Ag+ electrode (B.A.E. The measurements were carried out at room temperature (20 to 32°C). The scan rate during CV measurement was standardized to 0.1 V / sec. The oxidation potential Ea [V] and reduction potential Ec [V] were measured against the reference electrode. The potential of the reduction wave is defined as the midpoint potential of the reduction wave, and Ec is defined as the midpoint potential of the reduction-oxidation wave. The potential energy of the reference electrode relative to the vacuum level is -4.94 eV. Since it is known that the HOMO level [eV] = -4.94-Ea, the LUMO level [eV ]=-4.94-Ec, calculate the HOMO and LUMO levels. It is possible. [Explanation of symbols]

[0299] 101 Anode 102 Cathode 103 EL layer 111 Hole injection layer 112 Hole transport layer 112-1 First hole transport layer 112-2 Second 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 Electron injection buffer layer 400 boards 401 Anode 403 EL layer 404 Cathode 405 Sealing material 406 Sealing material 407 Sealing substrate 412 Pad 420 IC chip 501 Anode 502 Cathode 511 First Light Emitting Unit 512 Second Light Emitting Unit 513 Charge generation layer 601 Driver circuit section (source line driver circuit) 602 Pixel section 603 Drive circuit section (gate line drive circuit) 604 Sealing substrate 605 Sealing material 607 Space 608 Wiring 609 FPC (Flexible Printed Circuit) 610 Element substrate 611 Switching FET 612 Current control FET 613 Anode 614 Insulators 616 EL layer 617 Cathode 618 Light-emitting devices 951 PCB 952 Electrode 953 Insulation Layer 954 Partition layer 955 EL layer 956 Electrode 1001 board 1002 Undercoat insulating film 1003 Gate insulating film 1006 Gate electrode 1007 Gate electrode 1008 gate electrode 1020 First interlayer insulating film 1021 Second interlayer insulating film 1022 Electrode 1024W anode 1024R Anode 1024G anode 1024B Anode 1025 Bulkhead 1028 EL layer 1029 Cathode 1031 Sealing substrate 1032 Sealing material 1033 Transparent substrate 1034R Red color layer 1034G Green color layer 1034B Blue color layer 1035 Black Matrix 1036 Overcoat layer 1037 Third interlayer insulating film 1040 pixel section 1041 Drive circuit section 1042 Periphery 2001 Case 2002 light source 2100 Robot 2110 Arithmetic equipment 2101 Illuminance sensor 2102 Microphone 2103 Upper Camera 2104 Speaker 2105 Display 2106 Lower Camera 2107 Obstacle Sensor 2108 Moving mechanism 3001 Lighting equipment 5000 cabinets 5001 Display section 5002 Second display unit 5003 Speaker 5004 LED lamp 5005 Operation key 5006 Connection terminal 5007 Sensor 5008 Microphone 5012 Support part 5013 Earphones 5100 Cleaning Robot 5101 Display 5102 Camera 5103 Brush 5104 Operation button 5150 Personal Digital Assistant 5151 Case 5152 Display area 5153 Bend 5120 Garbage 5200 display area 5201 Display area 5202 Display area 5203 Display area 7101 Housing 7103 Display section 7105 Stand 7107 Display section 7109 Operation key 7110 Remote control device 7201 Main unit 7202 Case 7203 Display section 7204 keyboard 7205 External connection port 7206 Pointing Device 7210 Second display unit 7401 Housing 7402 Display section 7403 Operation button 7404 External connection port 7405 Speaker 7406 Microphone 9310 Mobile Information Terminal 9311 Display Panel 9313 Hinge 9315 chassis

Claims

[Claim 1] an anode, a cathode, and an EL layer located between the anode and the cathode; the EL layer has, from the anode side, a first layer, a second layer, a third layer, and a light-emitting layer; the first layer includes a first organic compound and a second organic compound; the second layer comprises a third organic compound; the third layer comprises a fourth organic compound; the light-emitting layer includes a fifth organic compound and a light-emitting center substance, the first organic compound is a substance that exhibits electron accepting properties toward the second organic compound, A light-emitting device, wherein a difference between a HOMO level of the fourth organic compound and a HOMO level of the fifth organic compound is 0.24 eV or less.

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