Light-emitting element

Abstract

To provide a long-life light-emitting element capable of emitting light with high luminance even when driving voltage is low.SOLUTION: A light-emitting element includes n (n is a natural number of 2 or more) EL layers between an anode and a cathode. Between the m-th (m is a natural number satisfying 1≤m≤n-1) and the (m+1)-th EL layer from the anode, there are a first layer containing a first donor material in contact with the m-th EL layer, a second layer containing an electron transport material and a second donor material in contact with the first layer, and a third layer containing a hole transport material and an acceptor material in contact with the second layer and the (m+1)-th EL layer.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a light-emitting element having a light-emitting layer between a pair of electrodes. The present invention relates to a light-emitting device, and an electronic device and a lighting device using the light-emitting device. [Background technology]

[0002] In recent years, there has been active development of light-emitting devices that use luminescent organic or inorganic compounds as luminescent materials. In particular, the electroluminescent device has a structure in which a light-emitting layer containing a light-emitting material is disposed between a pair of electrodes. Light-emitting elements called EL elements are thin, lightweight, have high-speed response, and are low in direct current. Due to its characteristics such as voltage driving, it is attracting attention as a next-generation flat panel display element. In addition, displays using EL elements have excellent contrast and image quality, and a wide viewing angle. In addition, since EL elements are surface light sources, they can be used in LCD displays. Applications as a light source for backlighting and illumination are also being considered.

[0003] The EL element has a pair of electrodes and a light-emitting layer containing a light-emitting substance provided between the pair of electrodes. In the EL element, when a current is passed through the light-emitting layer, the light-emitting material is excited and emits a predetermined color. In order to increase the luminance of an EL element, it is effective to pass a high current through the light-emitting layer. However, passing a large current through the EL element increases power consumption. In addition, passing a large current through the light-emitting layer accelerates the degradation of the EL element.

[0004] In view of this, a light-emitting element in which a plurality of light-emitting layers are stacked has been proposed (for example, Patent Document 1). Patent Document 1 discloses a device having a plurality of light-emitting units (hereinafter, also referred to as an EL layer in this specification). The document discloses a light-emitting device in which each light-emitting unit is partitioned by a charge generating layer. Specifically, a pentoxide layer is deposited on the metal doped layer which functions as the electron injection layer of the first light emitting unit. A charge generating layer made of sodium is provided, and a second light emitting unit is provided on the charge generating layer. The light emitting device disclosed in Patent Document 1 has a structure in which a current When current of the same density is applied, it emits light with higher brightness than a light-emitting device with one light-emitting layer. It is possible. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2003-272860 A Summary of the Invention [Problem to be solved by the invention]

[0006] An object of one embodiment of the present invention is to provide a light-emitting element that can emit light with high luminance.

[0007] Another object of one embodiment of the present invention is to provide a light-emitting element with a long lifetime.

[0008] Another object of one embodiment of the present invention is to provide a light-emitting element that can be driven at a low voltage. do.

[0009] Another object of one embodiment of the present invention is to provide a light-emitting device with reduced power consumption. do.

[0010] Another embodiment of the present invention is to provide an electronic device or a lighting device with reduced power consumption. This is one of the challenges. [Means for solving the problem]

[0011] One embodiment of the present invention has n (n is a natural number of 2 or more) EL layers between an anode and a cathode. Between the mth (m is a natural number, 1≦m≦n-1) EL layer and the m+1th EL layer from the pole, A first layer including a first donor material in contact with the m-th EL layer; a second layer including a electron transport material and a second donor material; and a second layer including an m+1-th EL a third layer including a hole transporting substance and an acceptor substance and in contact with the first layer; He is a child.

[0012] In addition, one embodiment of the present invention is a device having n (n is a natural number of 2 or more) EL layers between an anode and a cathode. Between the mth (m is a natural number, 1≦m≦n-1)th EL layer and the m+1th EL layer from the anode The mth EL layer includes a first electron transporting material and a first donor material. a first layer and a second layer having a lower lowest unoccupied molecular orbital level than a first electron transporting material in contact with the first layer; a second layer including an electron transporting material and a second donor material; and a second layer including an electron transporting material and an m+1-th a third layer including a hole transporting substance and an acceptor substance and in contact with the EL layer; It is a light emitting element.

[0013] Another embodiment of the present invention is a light-emitting device manufactured using the above-described light-emitting element.

[0014] Another embodiment of the present invention is an electronic device including the above-described light-emitting device.

[0015] Another embodiment of the present invention is a lighting device including the above-described light-emitting device. A lighting device is a light source that can be controlled to turn on and off, and is used to match a scene, visual object, and Light is used to illuminate the surroundings of people, to provide visual information, or to convey information by visual signals. This is a device designed to be useful in daily life.

[0016] In this specification, ordinal numbers such as first and second are used for convenience. It does not indicate the order of steps or the order of layers. It does not indicate a specific name as a matter for the purpose of Effect of the Invention

[0017] The light-emitting element of one embodiment of the present invention has a plurality of EL layers. Therefore, it is possible to emit light with high luminance. be.

[0018] Further, the light-emitting element of one embodiment of the present invention has a plurality of EL layers. It is possible to improve the life span when emitting light with high luminance.

[0019] In addition, the light-emitting element of one embodiment of the present invention can efficiently transfer carriers between a plurality of EL layers. Therefore, the driving voltage of the light-emitting element can be reduced.

[0020] Further, the light-emitting device of one embodiment of the present invention includes a light-emitting element with reduced driving voltage. Therefore, the power consumption of the light emitting device can be reduced.

[0021] Further, an electronic device or a lighting device according to one embodiment of the present invention includes a light-emitting device with reduced power consumption. Therefore, the power consumption of the electronic device or the lighting device can be reduced. [Brief description of the drawings]

[0022] [Figure 1] 1A and 1B show an example of an element structure and a band diagram of a light-emitting element described in Embodiment 1. [Diagram 2] 1A and 1B show an example of an element structure and a band diagram of a light-emitting element described in Embodiment 2. [Diagram 3] 1A and 1B show an example of an element structure and a band diagram of a light-emitting element described in Embodiment 3. [Figure 4] 13A to 13C are diagrams illustrating an example of an element structure of a light-emitting element described in Embodiment 4. [Diagram 5] 13A and 13B show an example of an element structure and an emission spectrum of a light-emitting element described in Embodiment 5. [Figure 6] FIG. 13 illustrates an active matrix light-emitting device described in Embodiment 6. [Figure 7] FIG. 13 illustrates a passive matrix light-emitting device described in Embodiment 6. [Figure 8] 11A to 11C are diagrams illustrating electronic devices described in Embodiment 7. [Figure 9] 13A and 13B illustrate a lighting device described in Embodiment 8. [Figure 10] 13A and 13B illustrate a lighting device described in Embodiment 8. [Figure 11] 1A and 1B are diagrams showing the element structure of a light-emitting element described in Examples 1 and 2. [Figure 12] 4A to 4C are graphs showing characteristics of a light-emitting element described in Example 1. [Figure 13] 4A to 4C are graphs showing characteristics of a light-emitting element described in Example 1. [Figure 14] 10A to 10C are graphs showing characteristics of a light-emitting element described in Example 2. [Figure 15] 10A to 10C are graphs showing characteristics of a light-emitting element described in Example 2. [Figure 16] 13A to 13C are graphs showing characteristics of a light-emitting element described in Example 3. [Figure 17] 13A to 13C are graphs showing characteristics of a light-emitting element described in Example 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following description, and may be modified in any form without departing from the spirit and scope of the present invention. It will be readily understood by those skilled in the art that various modifications may be made to the details. The present invention should not be construed as being limited to the description of the following embodiments.

[0024] (Embodiment 1) In this embodiment, one mode of a light-emitting element will be described with reference to FIG.

[0025] The light-emitting element shown in FIG. 1A has a light-emitting region between a pair of electrodes (anode 101 and cathode 102). The light-emitting element has a first EL layer 103 and a second EL layer 107 containing a positive electrode. From the electrode 101 side, an electron injection buffer layer 104 in contact with the first EL layer 103, an electron injection buffer The electronic relay layer 105 in contact with the buffer layer 104, and the electronic relay layer 105 and the second E It has a charge generating layer 106 in contact with the L layer 107 .

[0026] The electron injection buffer layer 104 serves to form an injection barrier when injecting electrons into the first EL layer 103. This layer is intended to alleviate the above-mentioned problem and to increase the efficiency of electron injection into the first EL layer 103. In this embodiment, the electron-injecting buffer layer 104 includes a donor material.

[0027] The electron relay layer 105 also serves the purpose of quickly transmitting electrons to the electron injection buffer layer 104. In this embodiment, the electron relay layer 105 is a layer formed of an electron transporting material and a donor. The electron-transporting material used in the electron-relay layer 105 is In addition to its high electron transport properties, its LUMO (Lowest Unoccupied Molecular Orbital) In this embodiment, The LUMO level of the first EL layer 103 and the acceptor level of the charge generation layer 106 are A material that occupies a level between the acceptor levels of a charge-transfer material. The electron transporting material used for the relay layer 105 is a material having a LUMO level of −5.0 eV or higher. It is preferable to use a material having an electron transporting property applied to the electron relay layer 105. It is more preferable to use a substance having a LUMO level of -5.0 eV or more and -3.0 eV or less. stomach.

[0028] The charge generation layer 106 is intended to generate holes and electrons that are carriers for the light-emitting element. In this embodiment, the charge generation layer 106 is a layer formed of a hole transporting substance and an acceptor. It is composed of a terpene material.

[0029] FIG. 1B shows a band diagram of the element structure of FIG. 1A. In the figure, 111 is the Fermi level of the anode 101, 112 is the Fermi level of the cathode 102, and 11 3 is the LUMO level of the first EL layer 103, and 114 is the donor property in the electron relay layer 105. donor level of the material, 115 is the LUMO level of the electron transport material in the electron relay layer 105 , 116 is the acceptor level of the acceptor material in the charge generating layer 106, and 117 is The LUMO level of the second EL layer 107 is shown.

[0030] In FIG. 1B, electrons generated in the charge generating layer 106 are transferred to the electron relay layer 105. The electron injection buffer layer 104 is then passed through the LUMO level of the electron transport material. Then, the LUMO level of the first EL layer 103 is changed to the LUMO level of the first EL layer 103. In this case, holes injected from the anode 101 and electrons injected from the charge generating layer 106 recombine. As a result, the first EL layer 103 emits light. In this case, holes injected from the charge generating layer 106 and electrons injected from the cathode 102 are regenerated. This causes the second EL layer 107 to emit light.

[0031] The light-emitting element described in this embodiment has an electron relay element including an electron transporting substance and a donor substance. The donor material has a layer 105 that lowers the LUMO level of the electron transport material. The electron relay layer 105 has an EL element having a lower LUMO level than the first EL layer 103. Since an electron transport material with a low LUMO level is used, the LUMO level is relatively low from the beginning. The LUMO level of the electron transport molecule is further lowered by the donor substance. The barrier for the daughter relay layer 105 to accept electrons from the charge generating layer 106 is reduced. The electrons received by the electron relay layer 105 are injected into the electron injection buffer layer 104 in a large amount. The electrons are rapidly injected into the first EL layer 103 without creating an entry barrier. This makes it possible to drive the device at a low voltage.

[0032] Next, specific examples of each of the above-mentioned substances will be described.

[0033] The donor substances contained in the electron injection buffer layer 104 and the electron relay layer 105 include , alkali metals, alkaline earth metals, or rare earth metals, or alkali metals, alkali Applying compounds of earth metals or rare earth metals (including oxides, halides, and carbonates) Specifically, lithium (Li), cesium (Cs), magnesium (Mg), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Europium (Eu), Examples of the metals include yttrium (Yb) and their compounds. Metal compounds are preferred because they have high electron injection properties.

[0034] The electron transporting substance contained in the electron relay layer 105 is a perylene derivative or a nitrogen-containing condensed It is possible to apply synthetic aromatic compounds, etc.

[0035] Specific examples of the perylene derivative include 3,4,9,10-perylenetetracarboxylic acid. Dianhydride (abbreviation: PTCDA), 3,4,9,10-perylenetetracarboxylic acid bicarbonate PTCBI, N,N'-dioctyl-3,4,9,10 -Perylenetetracarboxylic acid diimide (abbreviation: PTCDI-CH), N,N'-dihexyl Sil-3,4,9,10-perylenetetracarboxylic diimide (abbreviation: HexPTC), etc. Examples include:

[0036] Specific examples of the nitrogen-containing condensed aromatic compounds include pyrazino[2,3-f][1,10] Phenanthroline-2,3-dicarbonitrile (PPDN), 2,3,6,7,1 0,11-Hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation :HAT(CN)6), 2,3-diphenylpyrido[2,3-b]pyrazine (abbreviation: 2P YPR) 2,3-bis(4-fluorophenyl)pyrido[2,3-b]pyrazine (abbreviation: Furthermore, nitrogen-containing condensed aromatic compounds are stable compounds. Therefore, it is preferable as the electron transporting substance contained in the electron relay layer 105. Among aromatic compounds, compounds having electron-withdrawing groups such as cyano and fluoro groups are applied. This is preferable because it makes it easier for the electron-relay layer 105 to receive electrons.

[0037] Other examples include perfluoropentacene and 7,7,8,8-tetracyanoquinodimethane. (abbreviation: TCNQ), 1,4,5,8-naphthalenetetracarboxylic dianhydride (abbreviation: NTCDA), copper hexadecafluorophthalocyanine (abbreviation: F 16 CuPc), N,N '-Bis(2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadeca Fluorooctyl)-1,4,5,8-naphthalenetetracarboxylic diimide (abbreviation: N TCDI-C8F), 3',4'-dibutyl-5,5''-bis(dicyanomethylene)- 5,5''-Dihydro-2,2':5',2''-terthiophene (abbreviation: DCMT), Methanofullerenes (e.g., [6,6]-phenyl C 61 butyric acid methyl ester) etc. It can also be used as the electron transporting material contained in the relay layer 105 .

[0038] The hole transporting substance contained in the charge generating layer 106 is an aromatic amine compound, a carbazo derivatives, aromatic hydrocarbons, polymeric compounds (oligomers, dendrimers, polymers, etc.) Various organic compounds such as the above can be applied. Hole mobility is 1×10 -6 cm 2 / Vs or higher.

[0039] Specific examples of the aromatic amine compound include 4,4'-bis[N-(1-naphthyl)- N-phenylamino]biphenyl (abbreviation: NPB) and N,N'-bis(3-methylphenyl N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4',4''-tris(carbazol-9-yl)triphenylamine ( Abbreviation: TCTA), 4,4',4''-tris(N,N-diphenylamino)triphenyl TDATA, 4,4',4''-tris[N-(3-methylphenyl )-N-Phenylamino]triphenylamine (abbreviation: MTDATA), N,N'-bis (4-Methylphenyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DT DPPA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenyla N,N'-bis[4-[bis(3-methylphenyl) N,N'-diphenyl-[1,1'-biphenyl]-4,4' -diamine (abbreviation: DNTPD), 1,3,5-tris[N-(4-diphenylamino [phenyl]-N-phenylamino]benzene (abbreviation: DPA3B), and the like.

[0040] Specific examples of the carbazole derivative include 3-[N-(9-phenylcarbazole- 3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1 ), 3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino ]-9-phenylcarbazole (abbreviation: PCzPCA2), 3-[N-(1-naphthyl) -N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole ( Abbreviated as PCzPCN1). Other examples include 4,4'-di(N-carbazolyl)biphenyl Phenyl (abbreviation: CBP), 1,3,5-tris[4-(N-carbazolyl)phenyl] Benzene (abbreviation: TCPB), 9-[4-(10-phenyl-9-anthracenyl)phenyl] 1,4-bis[4-(N-carbazolyl)]-9H-carbazole (abbreviation: CzPA), [1,3,5,6-tetraphenylbenzene and the like.

[0041] Specific examples of the aromatic hydrocarbons include 2-tert-butyl-9,10-di(2-naphthalene). 2-tert-butyl-9,10-dianthracene (abbreviation: t-BuDNA), (1-naphthyl)anthracene, 9,10-bis(3,5-diphenylphenyl)anthracene Helical (abbreviation: DPPA), 2-tert-butyl-9,10-bis(4-phenylphenyl) 9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDBA), 9,10-diphenylanthracene (abbreviation: DNA), 2 -tert-Butylanthracene (abbreviation: t-BuAnth), 9,10-bis(4-methylanthracene) 9,10-bis[2-(1-naphthyl)anthracene (DMNA) 9,10-bis[2-(1-phenyl)-2-tert-butylanthracene naphthyl)phenyl]anthracene, 2,3,6,7-tetramethyl-9,10-di(1 -naphthyl)anthracene, 2,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene anthracene, 9,9'-bianthryl, 10,10'-diphenyl-9,9'-bianthryl Anthryl, 10,10'-bis(2-phenylphenyl)-9,9'-bianthryl, 10,10'-Bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9'- Bianthryl, anthracene, tetracene, rubrene, perylene, 2,5,8,11-tetracene The aromatic hydrocarbon may be vinyl, tert-butyl, or the like. Examples of aromatic hydrocarbons having a vinyl group include 4-vinyl group. ,4'-Bis(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi), 9,10 -Bis[4-(2,2-diphenylvinyl)phenyl]anthracene (abbreviation: DPVPA ) etc.

[0042] In addition, poly(N-vinylcarbazole) (abbreviation: PVK) and poly(4-vinyltriphenylphosphine) By using a polymer compound such as poly(vinylamine) (abbreviation: PVTPA) as a hole transporting material, It is also possible.

[0043] Furthermore, the hole transporting substance is 1×10 -6 cm 2 / Vs or more hole mobility However, as long as the material has a higher hole transporting property than an electron transporting property, Others than these may also be applied.

[0044] In addition, when the aromatic hydrocarbon is formed into a film by a vapor deposition method, the vapor deposition property during vapor deposition, From the viewpoint of the quality of the film after deposition, it is more preferable that the number of carbon atoms forming the condensed ring is 14 to 42. I wish.

[0045] The acceptor material contained in the charge generating layer 106 is a transition metal oxide or an element periodic It is possible to apply oxides of metals belonging to groups 4 to 8 in the table. Vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, Examples of the metal oxides include tungsten, manganese oxide, and rhenium oxide. Oxides are preferred because they have a high electron-accepting property. Furthermore, the acceptor material is molybdenum oxide. Molybdenum oxide is more preferable. Molybdenum oxide has a characteristic of low hygroscopicity. is doing.

[0046] In addition, the electron injection buffer layer 104, the electron relay layer 105, and the charge generation layer 106 are formed. The manufacturing method includes dry processes (e.g., vacuum deposition, sputtering, etc.), wet deposition, and Regardless of the process (e.g., inkjet method, spin coating method, coating method, etc.), The method can be applied.

[0047] Next, specific examples of the above-mentioned anode 101 and cathode 102 will be described.

[0048] The anode 101 is preferably a metal having a large work function (specifically, 4.0 eV or more). , alloys, electrically conductive compounds, and mixtures thereof can be used. Specifically, indium oxide-tin oxide (ITO), Indium oxide containing silicon or silicon oxide - tin oxide, indium oxide - Zinc oxide (IZO: Indium Zinc Oxide), tungsten oxide and oxide Examples of the conductive metal oxide include zinc-containing indium oxide.

[0049] The thin film of the conductive metal oxide can be prepared by a sputtering method. The conductive metal oxide can also be produced by applying the sol-gel method. For example, indium oxide-zinc oxide (IZO) has a 1-20 watt-hour resistance to indium oxide. It can be formed by sputtering using a target containing t% zinc oxide. In addition, indium oxide containing tungsten oxide and zinc oxide is It contains 0.5-5wt% tungsten oxide and 0.1-1wt% zinc oxide. It can be formed by a sputtering method using a target.

[0050] Others include gold (Au), platinum (Pt), nickel (Ni), tungsten (W), and chromium. (Cr), Molybdenum (Mo), Iron (Fe), Cobalt (Co), Copper (Cu), Palladium (Pb) Pd, Ti, and their nitrides (e.g., titanium nitride, etc.), as well as oxides. Molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, manganese oxide, and Oxides such as titanium oxide and poly(3) oxide can be used as the anode 101. ,4-ethylenedioxythiophene) / poly(styrenesulfonic acid) (abbreviation: PEDOT / PSS), polyaniline / poly(styrenesulfonic acid) (abbreviation: PAni / PSS), etc. However, it is also possible to use the conductive polymer as a part of the first EL layer 103. In the case where a charge generating layer is provided in contact with the anode 101, various conductive materials can be used regardless of the magnitude of the work function. It is possible to apply a conductive material to the anode 101. The charge generating layer 106 is formed between the first EL layer 103 and the second EL layer 107. The configuration can be applied.

[0051] The cathode 102 is preferably made of a material having a small work function (specifically, 3.8 eV or less). (Preferably) metals, alloys, electrically conductive compounds, and mixtures thereof can be applied. Specifically, elements belonging to the first or second group of the periodic table, namely lithium (Li), cesium (Cs), and other alkali metals, magnesium (Mg), calcium (C a), alkaline earth metals such as strontium (Sr), and alloys containing these (MgAg , AlLi, etc.), as well as rare earth metals such as europium (Eu) and ytterbium (Yb) and alloys containing these. In addition, alkali metals, alkaline earth metals, and The alloy film containing these elements can be formed by vacuum deposition. Alloys containing alkali metals and alkaline earth metals can also be formed by sputtering. It is.

[0052] In addition, compounds of alkali metals, alkaline earth metals, or rare earth metals (e.g., fluoride Lithium (LiF), lithium oxide (LiOx), cesium fluoride (CsF), fluoride Thin films of fluoride (CaF2, Erbium fluoride (ErF3, etc.) and aluminum, etc. It is also possible to form the cathode 102 by laminating a metal film of the first When a charge generating layer is provided in contact with the cathode 102 as a part of the EL layer 107 of the second embodiment, It is possible to apply various conductive materials to the cathode 102 regardless of the magnitude of the function. The charge generating layer is provided between the first EL layer 103 and the second EL layer 107. It is possible to apply the same structure as the charge generating layer 106 to be used.

[0053] In the light-emitting element shown in this embodiment, at least one of the anode 101 and the cathode 102 At least one of them needs to transmit the light of the emitted wavelength. Transparency is achieved by using a transparent electrode such as ITO. Alternatively, this can be ensured by reducing the film thickness of the electrode.

[0054] Next, specific examples of the above-mentioned first EL layer and second EL layer will be described.

[0055] The first EL layer 103 and the second EL layer 107 are light-emitting layers having at least a light-emitting material. That is, the first EL layer 103 and the second EL layer 107 are The first EL layer 10 may have a structure in which a light-emitting layer and a layer other than the light-emitting layer are laminated. The light-emitting layer included in the first EL layer 103 and the light-emitting layer included in the second EL layer 107 are different from each other. In addition, the first EL layer 103 and the second EL layer 107 may each independently be The light-emitting layer may have a laminated structure in which an optical layer and a layer other than the light-emitting layer are laminated.

[0056] As layers other than the light-emitting layer, a layer containing a hole-injecting substance (hole-injecting layer), a layer containing a hole-transporting substance, a layer containing an electron transporting substance (electron transport layer); a layer containing an electron injecting substance (electron transport layer); layer (electron injection layer), a layer containing a bipolar (electron transporting and hole transporting) material, etc. These can be configured in appropriate combinations.

[0057] The first EL layer 103 and the second EL layer 107 serve as a hole injection layer, a hole transport layer, and a light emitting layer. Specific examples of materials constituting each layer when the layer is composed of an electron transport layer, an electron injection layer, and an electron transfer layer are shown below. vinegar.

[0058] The hole injection layer is a layer containing a hole injection material. Positive holes in rhodium, vanadium oxide, ruthenium oxide, tungsten oxide, manganese oxide, etc. Other examples include phthalocyanine (abbreviated as H2Pc) and copper phthalocyanine. Phthalocyanine compounds such as CuPc and PEDOT / PSS Polymers such as those referred to as ZnO and ZnCl may also be used as the hole-injecting material.

[0059] The hole transport layer is a layer containing a hole transporting substance. The hole transporting substance is NPB. (abbreviation), TPD (abbreviation), TCTA (abbreviation), TDATA (abbreviation), MTDATA (abbreviation) (named) and 4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N- Aromatic amine compounds such as phenylamino]biphenyl (abbreviation: BSPB), and PCz PCA1(abbreviation), PCzPCA2(abbreviation), PCzPCN1(abbreviation), CBP(abbreviation) , TCPB (abbreviation), and CzPA (abbreviation) are carbazole derivatives. PVK (abbreviation), PVTPA (abbreviation), poly[N-(4-{N'-[4-(4-diphenyl phenyl-N'-phenylamino}phenyl)methacrylamide (abbreviation: PTPDMA), poly[N,N'-bis(4-butylphenyl)-N,N'-bi Poly(phenyl)benzidine (abbreviation: Poly-TPD) was used as the hole transport material. The materials mentioned here are mainly 1×10 -6 cm 2 / Vs or more positive However, if the material has a higher hole transporting property than the electron transporting property, The hole transport layer may be formed not only of a single layer but also of a layer made of the above-mentioned materials. A laminate of two or more layers made of the above materials may also be used.

[0060] The light-emitting layer is a layer containing a light-emitting substance. The light-emitting substance is a fluorescent compound shown below. and phosphorescent compounds can be applied.

[0061] The fluorescent compound is N,N'-bis[4-(9H-carbazol-9-yl) Phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviation: YGA2S ), 4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl ) Triphenylamine (abbreviation: YGAPA), 4-(9H-carbazol-9-yl)- 4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGA PPA), N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl] 9H-carbazol-3-amine (abbreviation: PCAPA), perylene, 2,5,8, 11-Tetra-tert-butylperylene (abbreviation: TBP), 4-(10-phenyl-9 -anthryl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenyl Amine (abbreviation: PCBAPA), N,N''-(2-tert-butylanthracene-9 ,10-diyldi-4,1-phenylene)bis[N,N',N'-triphenyl-1,4 -phenylenediamine] (abbreviation: DPABPA), N,9-diphenyl-N-[4-(9 ,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine ( Abbreviation: 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl] 2DPAP PA), N,N,N',N',N'',N'',N''',N'''-Octaphenyldiphenyl Benzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), Marine 30, N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9 H-Carbazole-3-amine (abbreviation: 2PCAPA), N-[9,10-bis(1,1 '-Biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazo N-(9,10-diphenyl-2-amine) Tolyl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DP APA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthryl ]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPABP hA), 9,10-bis(1,1'-biphenyl-2-yl)-N-[4-(9H-cal 2Y GABPhA), N,N,9-triphenylanthracene-9-amine (abbreviation: DPhA PhA), Coumarin 545T, N,N'-Diphenylquinacridone, (abbreviation: DPQd) , Rubrene, 5,12-bis(1,1'-biphenyl-4-yl)-6,11-diphenyl BPT, 2-(2-{2-[4-(dimethylamino)phenyl] ethenyl}-6-methyl-4H-pyran-4-ylidene)propanedinitrile (abbreviation: D CM1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H -benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}p Dopanedinitrile (abbreviation: DCM2), N,N,N',N'-tetrakis(4-methylfuran) p-mPhTD, 7,14-diphenyltetracene-5,11-diamine Nyl-N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a ]Fluoranthene-3,10-diamine (abbreviation: p-mPhAFD), 2-{2-isopropyl propyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro- 1H,5H-Benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-yl 2-{2-tert-butyl-6-(2-phenylenedinitrile) [2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H- Benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}pro Pandinitrile (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-tetramethylphenyl] Chil-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizine-9-yl Bis(ethyl)ethenyl)-4H-pyran-4-ylidene}propanedinitrile (abbreviation: BisDC JTM) etc.

[0062] The phosphorescent compound is bis[2-(4',6'-difluorophenyl)pyridinium] To-N,C 2’ ]Iridium(III) tetrakis(1-pyrazolyl)borate (abbreviation: FIr6), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ] Iridium(III) picolinate (abbreviation: FIrpic), bis[2-(3',5'- Bis(trifluoromethylphenyl)pyridinato-N,C 2’ ]Iridium(III) pico Ir(CF3ppy)2(pic) (fluorophenyl)pyridinato-N,C 2’ ]Iridium(III) acetylacetonate (abbreviation: FIracac), tris(2-phenylpyridinato)iridium(III) ( Abbreviation: Ir(ppy)3), bis(2-phenylpyridinato)iridium(III) acetone Ir(ppy)2(acac)), bis(benzo[h]quinolinol Nat)iridium(III) acetylacetonate (abbreviation: Ir(bzq)2(acac )), Bis(2,4-diphenyl-1,3-oxazolato-N,C 2’ ) Iridium (I II) Acetylacetonate (abbreviation: Ir(dpo)2(acac)), bis[2-(4 '-Perfluorophenylphenyl)pyridinato]iridium(III) acetylacetonate Ir(p-PF-ph)2(acac)), bis(2-phenylbenzothiamine Azolat-N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: Ir(bt )2(acac)), bis[2-(2'-benzo[4,5-α]thienyl)pyridinato- N,C 3’ ]Iridium(III) acetylacetonate (abbreviation: Ir(btp)2(a cac)), bis(1-phenylisoquinolinato-N,C 2’ ) Iridium(III) A Cetylacetonate (abbreviation: Ir(piq)2(acac)), (acetylacetonate) Bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III)( Abbreviation: Ir(Fdpq)2(acac)), (acetylacetonato)bis(2,3,5- Triphenylpyrazinate)iridium(III) (abbreviation: Ir(tppr)2(acac )), 2,3,7,8,12,13,17,18-octaethyl-21H,23H-pol Platinum(II) fluorine (abbreviation: PtOEP), tris(acetylacetonato)(monophenyl) Anthroline) terbium(III) (abbreviation: Tb(acac)3(Phen)), tri S(1,3-diphenyl-1,3-propanedionato)(monophenanthroline) Eu(DBM)3(Phen)

[0113] -3,3,3-trifluoroacetonato](monophenanthroline)europium( III) (abbreviation: Eu(TTA)3(Phen)).

[0063] The light-emitting layer preferably has a structure in which the light-emitting substance is dispersed in a host material. The host materials are NPB (abbreviation), TPD (abbreviation), TCTA (abbreviation), and TDA. Aromatic amine compounds such as TA (abbreviation), MTDATA (abbreviation), and BSPB (abbreviation), P CzPCA1 (abbreviation), PCzPCA2 (abbreviation), PCzPCN1 (abbreviation), CBP (abbreviation) Carbazole derivatives such as TCPB (abbreviation), CzPA (abbreviation), and PVK (abbreviation) (abbreviation), PVTPA (abbreviation), PTPDMA (abbreviation), Poly-TPD (abbreviation), etc. Hole transporting materials including molecular compounds, and tris(8-quinolinolato)aluminum (abbreviation abbreviation: Alq), tris(4-methyl-8-quinolinolato)aluminum (abbreviation: Almq 3) Bis(10-hydroxybenzo[h]quinolinato)beryllium (abbreviation: BeBq2 ), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum ( Metal complexes with a quinoline or benzoquinoline skeleton, such as bis(trifluoromethyl)phthalic acid (abbreviation: BAlq), [2-(2-hydroxyphenyl)benzoxazolato]zinc (abbreviation: Zn(BOX)2 ), bis[2-(2-hydroxyphenyl)benzothiazolato]zinc (abbreviation: Zn(BT Z)2) and other metal complexes with oxazole and thiazole ligands, (phenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole ( Abbreviated as PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4- Oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl (abbreviation: CO1 1), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl) )-1,2,4-triazole (abbreviation: TAZ), bathophenanthroline (abbreviation: BPh en), bathocuproine (abbreviation: BCP), poly[(9,9-dihexylfluorene- 2,7-diyl)-co-(pyridine-3,5-diyl)] (abbreviation: PF-Py), and Poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2'-bipyridine) Examples of electron transporting substances include PF-BPy, etc. can be.

[0064] The electron transport layer is a layer containing an electron transporting substance. The electron transporting substance is Alq (abbreviation), Almq3 (abbreviation), BeBq2 (abbreviation), and BAlq (abbreviation) Metal complexes having a phosphorus skeleton or a benzoquinoline skeleton, as well as Zn(BOX)2 (abbreviation) and Metals with oxazole or thiazole ligands, such as Zn(BTZ)2 (abbreviation) In addition to metal complexes, PBD (abbreviation), OXD-7 (abbreviation) , CO11(abbreviation), TAZ(abbreviation), BPhen(abbreviation), BCP(abbreviation), PF- Py (abbreviation), PF-BPy (abbreviation), etc. can also be used as the electron transport material. The substances mentioned here are mainly 1×10 -6 cm 2 / Vs or higher electron mobility In addition, any other material that has a higher electron transporting property than a hole transporting property may be used. The electron transport layer may be a single layer or a double layer of the above-mentioned material. A laminate of the above may be used.

[0065] The electron injection layer is a layer containing an electron injection material. Lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF2), etc. Examples of the electron transporting material include alkali metals, alkaline earth metals, and compounds thereof. Contains alkali metals, alkaline earth metals, or compounds thereof (e.g., Alq (abbreviation) containing magnesium (Mg) is used as the electron injection material. By adopting such a structure, the electrons from the cathode 102 The injection efficiency can be further improved.

[0066] When a charge generating layer is provided in the first EL layer 103 or the second EL layer 107, the charge generating layer is The charge generating layer is a layer containing a hole transporting substance and an acceptor substance. In addition to the case where a hole transporting substance and an acceptor substance are contained in the film, A layer containing a substance and a layer containing an acceptor substance may be stacked. In the case of the structure, the layer containing the acceptor material is in contact with the anode 101 or the cathode 102. It shall be constructed.

[0067] By providing a charge generating layer in the first EL layer 103 or the second EL layer 107, an electrode can be formed. It is possible to form the anode 101 or the cathode 102 without considering the work function of the material to be formed. The charge generating layer provided in the first EL layer 103 or the second EL layer 107 is Similar to the charge generating layer 106 provided between the first EL layer 103 and the second EL layer 107 described above, The above-mentioned configurations and materials can be applied. It is decided.

[0068] By laminating these layers in an appropriate combination, the first EL layer 103 and In addition, the first EL layer 103 and the second EL layer 107 can be formed. As a method for forming 107, various methods (e.g., dry method, wet method, etc.) can be used depending on the material used. For example, a vacuum deposition method, an ink jet method, or a spin coater method may be used. Each layer may be formed by a different method.

[0069] The light-emitting element shown in this embodiment is manufactured by combining the above-mentioned substances. It is possible to obtain light emission from the light-emitting material described above from the light-emitting element. Therefore, various emission colors can be obtained by changing the type of luminescent material used in the luminescent layer. In addition, by using multiple luminescent materials with different luminescent colors, a broad It is also possible to obtain light emission with a wide spectrum or white light emission.

[0070] In this embodiment, a light emitting element having two EL layers is described. The number of EL layers is not limited to two, and may be more than two, for example, three. When the light-emitting element has n (n is a natural number of 2 or more) EL layers, m (m is a natural number, 1≦ Between the (m≦n-1)th EL layer and the (m+1)th EL layer, an electron injection barrier is placed in the order from the anode side. By stacking a buffer layer, an electron relay layer, and a charge generating layer, the driving voltage of the light-emitting element is reduced. It can be reduced.

[0071] In addition, the light-emitting element shown in this embodiment mode can be manufactured over various substrates. Examples of the material that can be used include glass, plastic, metal plates, and metal foils. In addition, when light emitted from a light-emitting element is extracted from the substrate side, a light-transmitting substrate may be used. However, the substrate may be any substrate as long as it functions as a support in the manufacturing process of the light-emitting element. Other than these may also be used.

[0072] Note that the contents described in this embodiment mode may be used in appropriate combination with contents described in other embodiment modes. There can be.

[0073] (Embodiment 2) In this embodiment mode, an example of the light-emitting element described in Embodiment 1 will be described. Specifically, The electron injection buffer layer 104 of the light emitting element shown in the first embodiment is made of a donor material. The case where the electrode is formed of a single layer will be described with reference to FIGS. 2(A) and 2(B).

[0074] The light-emitting element shown in this embodiment has a pair of electrodes (anode 101 and cathode 102) as shown in FIG. A first EL layer 103 and a second EL layer 107 including a light-emitting region are sandwiched between the electrodes 102. In addition, the light-emitting element has an electron injection layer in contact with the first EL layer 103 from the anode 101 side. a buffer layer 104, an electron relay layer 105 in contact with the electron injection buffer layer 104, and It has a charge generating layer 106 in contact with the electron relay layer 105 and the second EL layer 107 .

[0075] In this embodiment, the anode 101, the cathode 102, the first EL layer 103, the electron relay layer The structure described in the first embodiment is used for the charge generating layer 105, the charge generating layer 106, and the second EL layer 107. Therefore, the description of the first embodiment is incorporated herein. Let us assume that.

[0076] In this embodiment, the material used for the electron injection buffer layer 104 is lithium. Alkali metals such as Li and Cs, magnesium (Mg), calcium ( Ca), and alkaline earth metals such as strontium (Sr), europium (Eu) and Rare earth metals such as ytterbium (Yb), alkali metal compounds (oxides such as lithium oxide) , halides, carbonates such as lithium carbonate and cesium carbonate), alkaline earth metal compounds Compounds (including oxides, halides, and carbonates), and rare earth metal compounds (including oxides, halides, and carbonates) Examples of materials with high electron injection properties include those containing fluorides and carbonates. Since highly injectable substances are stable in air, they are easy to manufacture and suitable for mass production. preferable.

[0077] The light-emitting element shown in this embodiment mode uses the above-mentioned metal or The electron injection buffer layer 104 is formed in a single layer of the compound. To avoid voltage rise, the film is made very thin (specifically, less than 1 nm). After the electron transport layer 108 is formed, the electron injection buffer layer 104 is formed on the electron transport layer 108. In the case of forming the first EL layer, a part of the material forming the electron injection buffer layer 104 is It may also be present in the electron transport layer 108, which is part of the layer 103. The input buffer layer 104 is connected to the electron relay layer 105 and the electron transport layer which is a part of the first EL layer 103. In other words, the first layer 108 is located at the interface of the first layer 108. The EL layer 103 of the first embodiment is provided with an electron transport layer 108 in contact with the electron injection buffer layer 104. It is preferable to form the

[0078] FIG. 2B shows a band diagram of the element structure of FIG. 2A. In this case, electrons are injected into the interface between the electron relay layer 105 and the first EL layer 103 (electron transport layer 108). By providing the input buffer layer 104, the charge generation layer 106 and the first EL layer 103 (the charge Therefore, the injection barrier between the charge generating layer 106 and the charge transport layer 108 can be reduced. Therefore, the electrons generated at the first EL layer 103 can be easily injected into the first EL layer 103 .

[0079] In addition, by adopting the structure of the electron injection buffer layer shown in this embodiment, The electron injection buffer layer (formed by adding a donor material to an electron transport material) described later in 3. In comparison with a layer in which a light-emitting element is provided, the driving voltage of the light-emitting element can be reduced.

[0080] Note that the contents described in this embodiment mode may be used in appropriate combination with contents described in other embodiment modes. There can be.

[0081] (Embodiment 3) In this embodiment mode, an example of the light-emitting element described in Embodiment 1 will be described. Specifically, The electron injection buffer layer 104 of the light-emitting element shown in the first embodiment is made of an electron transporting material. The case where the donor substance is included will be described with reference to FIGS. 3(A) and 3(B). do.

[0082] The light-emitting element shown in this embodiment has a pair of electrodes (anode 101 and cathode 102) as shown in FIG. A first EL layer 103 and a second EL layer 107 including a light-emitting region are sandwiched between the electrodes 102. In addition, the light-emitting element has an electron injection layer in contact with the first EL layer 103 from the anode 101 side. a buffer layer 104, an electron relay layer 105 in contact with the electron injection buffer layer 104, and It has a charge generating layer 106 in contact with the electron relay layer 105 and the second EL layer 107 .

[0083] The electron-injecting buffer layer 104 contains an electron-transporting material and a donor material. In this embodiment, the mass ratio of the electron transporting substance to the electron transporting substance is 0.001 or more and 0.1 or less. It is preferable to add a donor substance in a ratio of 1:1 to 1:1. This makes it possible to form an electron injection buffer having a good film quality. In addition, the electron injection buffer layer 104 has good reactivity. can be done.

[0084] In this embodiment, the anode 101, the cathode 102, the first EL layer 103, the electron relay layer 1 The structure and the configuration described in the first embodiment are used for the charge generating layer 105, the charge generating layer 106, and the second EL layer 107. Therefore, the description of the first embodiment is incorporated herein. do.

[0085] In this embodiment, the electron transport material contained in the electron injection buffer layer 104 is Alq (abbreviation), Almq3 (abbreviation), BeBq2 (abbreviation), BAlq (abbreviation), etc. Metal complexes having a quinoline or benzoquinoline skeleton, Zn(BOX)2 (abbreviation), Z Metal complexes with oxazole and thiazole ligands, such as n(BTZ)2 (abbreviation), PBD (abbreviation), OXD-7 (abbreviation), CO11 (abbreviation), TAZ (abbreviation), BPhen (abbreviation), BCP (abbreviation), etc. The substances mentioned here are mainly 1×10 -6 cm 2 It is a material that has an electron mobility of 0.1V or more.

[0086] In addition, we have also developed polymer compounds such as PF-Py (abbreviation) and PF-BPy (abbreviation). It is possible to use it as an electron transporting material contained in the injection buffer layer 104 .

[0087] In this embodiment, the donor material contained in the electron injection buffer layer 104 is The following metals are considered to be oxides: alkali metals, alkaline earth metals, rare earth metals, and their compounds. , halides, and carbonates). Organic compounds such as TTN, nickelocene, and decamethylnickelocene are used as electron injection buffers. It is also possible to apply it as a donor material contained in layer 104 .

[0088] In this embodiment, the first EL layer 103 includes an electron injection buffer layer 104. The electron transport layer 108 may be formed in contact with the electron injection buffer. When the electron injection buffer layer 104 is formed in contact with the electron transport layer 104, and an electron transporting material used in the electron transport layer 108 which is a part of the first EL layer 103. may be the same material or different materials.

[0089] The light-emitting element shown in this embodiment mode has a first EL layer 103 and an electron emitting layer 104 as shown in FIG. Between the layer 105, an electron injection buffer layer 104 containing an electron transport material and a donor material is provided. A notable feature is that 04 is provided.

[0090] FIG. 3B shows a band diagram of the device structure of FIG. 3A. By forming the far layer 104, the electron relay layer 105 and the first EL layer 103 (electron Therefore, the injection barrier between the charge generating layer 106 and the charge transport layer 108 can be reduced. The electrons generated at the first EL layer 103 can be easily injected into the first EL layer 103 .

[0091] Note that the contents described in this embodiment mode may be used in appropriate combination with contents described in other embodiment modes. There can be.

[0092] (Embodiment 4) In this embodiment mode, an example of the light-emitting element described in Embodiment 1 will be described. Specifically, The structure of the charge generation layer 106 included in the light-emitting element described in Embodiment 1 is shown in FIG. This will be explained using (B).

[0093] The light-emitting element shown in this embodiment has a pair of electrodes (anode 1) as shown in FIGS. A first EL layer 103 and a second EL layer 107 including a light-emitting region are sandwiched between the cathode 102 and the cathode 101. In addition, the light-emitting element is in contact with the first EL layer 103 from the anode 101 side. An electron injection buffer layer 104, and an electron relay layer 105 in contact with the electron injection buffer layer 104. and a charge generating layer 106 in contact with the electron relay layer 105 and the second EL layer 107. In FIG. 4(A) and (B), an anode 101, a cathode 102, a first EL layer 103, an electron injection The input buffer layer 104, the electron relay layer 105, and the second EL layer 107 are formed as in the embodiment. The structures and materials described in 1 to 3 can be used. The explanations from 1 to 3 shall be cited.

[0094] In the light-emitting element shown in FIG. 4(A) and (B), the charge generation layer 106 is made of a hole transporting substance. The charge generation layer 106 is a layer containing a hole transporting substance. When the acceptor substance extracts electrons from the cation, holes and electrons are generated.

[0095] The charge generation layer 106 shown in FIG. 4A is a layer in which a hole transporting substance and an acceptor substance are contained in the same film. In this case, the mass ratio of the hole transporting substance is 0.1 By adding an acceptor material at a ratio of 0.1 to 4.0, the charge generating layer 106 This is preferable because it facilitates the generation of carriers in the electrode.

[0096] In FIG. 4A, an acceptor substance is doped into a hole transporting substance. Therefore, even if the charge generating layer 106 is made thick, an increase in the driving voltage can be suppressed. Therefore, the increase in the driving voltage of the light emitting element is suppressed, and the color purity is improved by optical adjustment. In addition, by making the charge generating layer 106 thick, it is possible to prevent a short circuit of the light emitting element. It is possible.

[0097] On the other hand, the charge generating layer 106 shown in FIG. 4B is a hole transporting layer in contact with the second EL layer 107. The layer 106a containing the substance and the layer 10 containing the acceptor substance in contact with the electron-relay layer 105 are In the charge generating layer 106 of the light emitting element shown in FIG. The electron transfer occurs between the hole transporting substance and the acceptor substance. The electron transfer complex is a layer 106a containing a hole transporting substance and a layer 106b containing an acceptor substance. Therefore, the light-emitting element shown in FIG. Even if the thickness of the raw layer 106 is increased, the absorption band of visible light is unlikely to be formed, which is preferable. .

[0098] The hole transporting substance contained in the charge generating layer 106 may be an aromatic amine compound, a cation compound, or a cation-containing compound. carbazole derivatives, aromatic hydrocarbons, polymer compounds (oligomers, dendrimers, polymers Various organic compounds such as benzene, benzenediamine, benzenediaminetetraacetate ...

[0099] Specific examples of the aromatic amine compound include NPB (abbreviation), TPD (abbreviation), and TCT. A(abbreviation), TDATA(abbreviation), MTDATA(abbreviation), DTDPPA(abbreviation), DP Examples include AB (abbreviation), DNTPD (abbreviation), DPA3B (abbreviation), etc.

[0100] Specific examples of the above carbazole derivatives include PCzPCA1 (abbreviation), PCzPCA2 (abbreviation), PCzPCN1 (abbreviation), etc. Others include CBP (abbreviation), TCPB (abbreviation), CzPA (abbreviation), 1,4-bis[4-(N-carbazolyl)phenyl]-2 , 3,5,6-tetraphenylbenzene, etc.

[0101] Specific examples of the aromatic hydrocarbons include t-BuDNA (abbreviation), DPPA (abbreviation), t-BuDBA (abbreviation), DNA (abbreviation), DPAnth (abbreviation), t-BuAnth ( abbreviation), DMNA (abbreviation), 9,10-bis[2-(1-naphthyl)phenyl]-2-t ert-Butylanthracene, 9,10-bis[2-(1-naphthyl)phenyl]anthracene helical, 2,3,6,7-tetramethyl-9,10-di(1-naphthyl)anthracene, 2,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene, 9,9' -bianthryl, 10,10'-diphenyl-9,9'-bianthryl, 10,10'- Bis(2-phenylphenyl)-9,9'-bianthryl, 10,10'-bis[(2, 3,4,5,6-pentaphenyl)phenyl]-9,9'-bianthryl, anthracene , tetracene, rubrene, perylene, 2,5,8,11-tetra(tert-butyl)pe rylene, etc. The aromatic hydrocarbon may have a vinyl skeleton. Examples of aromatic hydrocarbons having a vinyl group include DPVBi (abbreviation) and DPVP. A (abbreviation), etc.

[0102] In addition, polymer compounds such as PVK (abbreviation) and PVTPA (abbreviation) are used as the hole transporting material. It is also possible to apply it as follows.

[0103] Furthermore, the hole transporting substance is 1×10 -6 cm 2 / Vs or more hole mobility However, as long as the material has a higher hole transporting property than an electron transporting property, Others than these may also be applied.

[0104] In addition, when the aromatic hydrocarbon is formed into a film by a vapor deposition method, the vapor deposition property during vapor deposition, From the viewpoint of the quality of the film after deposition, it is more preferable that the number of carbon atoms forming the condensed ring is 14 to 42. I wish.

[0105] The acceptor material contained in the charge generating layer 106 is 7,7,8,8-tetraphenylene sulfide. Ano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), Chlor Examples of the acceptor material include transition metal oxides. In addition, oxides of metals belonging to groups 4 to 8 of the periodic table can be used. Specifically, vanadium oxide, niobium oxide, tantalum oxide, Chromium, molybdenum oxide, tungsten oxide, manganese oxide, and rhenium oxide are electron-accepting. Furthermore, the acceptor material is preferably molybdenum oxide. It is more preferable that the molybdenum oxide has a feature that it has low hygroscopicity.

[0106] Note that the contents described in this embodiment mode may be used in appropriate combination with contents described in other embodiment modes. There can be.

[0107] (Embodiment 5) In this embodiment mode, an example of the light-emitting element described in Embodiment 1 will be described. Specifically, An example of the light-emitting element described in Embodiment 1 will be described with reference to FIGS.

[0108] The light-emitting element shown in this embodiment has a pair of electrodes (anode 101 and cathode 102) as shown in FIG. A first EL layer 103 and a second EL layer 107 including a light-emitting region are sandwiched between the electrodes 102. In addition, the light-emitting element has an electron injection layer in contact with the first EL layer 103 from the anode 101 side. a buffer layer 104, an electron relay layer 105 in contact with the electron injection buffer layer 104, and It has a charge generating layer 106 in contact with the electron relay layer 105 and the second EL layer 107 .

[0109] In this embodiment, the anode 101, the cathode 102, the electron injection buffer layer 104, the electron The charge generating layer 105 and the charge generating layer 106 are formed of the same materials and have the same structures as those described in the first to fourth embodiments. Therefore, the description of the first to fourth embodiments can be used here. do.

[0110] In this embodiment, the first EL layer 103 has a peak in the blue to blue-green wavelength region. The first light-emitting layer 103a has an emission spectrum having a peak in the yellow to orange wavelength region. The second EL layer 107 has a second light-emitting layer 103b that exhibits an emission spectrum corresponding to the first EL layer 103b. The third light-emitting layer 107 exhibits an emission spectrum having a peak in the blue-green to green wavelength region. a) and a fourth light-emitting layer 107 having an emission spectrum with a peak in the orange to red wavelength region. The first light-emitting layer 103a and the second light-emitting layer 103b are stacked in the reverse order. The third light-emitting layer 107a and the fourth light-emitting layer 107b may be stacked in the reverse order. good.

[0111] In such a light-emitting device, the anode 101 side is positive and the cathode 102 side is negative. When a bias is applied, holes are injected from the anode 101 and charges are generated in the charge generating layer 106. The electrons injected through the electron relay layer 105 and the electron injection buffer layer 104 are The electrons recombine in the light-emitting layer 103a or the second light-emitting layer 103b. This produces a first light Furthermore, electrons injected from the cathode 102 and charges generated in the charge generating layer 106 are generated. The injected holes are recombined in the third light-emitting layer 107a or the fourth light-emitting layer 107b. This results in a second emission of light 340.

[0112] FIG. 5B is a schematic diagram showing the emission spectra of the first emission 330 and the second emission 340. The first emission 330 is a light-emitting layer including the first light-emitting layer 103a and the second light-emitting layer 103b. Therefore, the wavelength range of blue to blue-green and the wavelength range of yellow to The emission spectrum has peaks in both the orange wavelength range. The second light source 103 emits white or near-white light in two wavelengths. Light 340 is a combination of light emitted from both the third light-emitting layer 107a and the fourth light-emitting layer 107b. Therefore, it has peaks in both the blue-green to green wavelength region and the orange-red wavelength region. That is, the second EL layer 107 has an emission spectrum having a peak. Unlike 03, this is a two-wavelength type that emits white or near-white light.

[0113] Therefore, the light emitting device in this embodiment has a first emission 330 and a second emission 34. The result of overlapping 0s is the blue to blue-green wavelength range, the blue-green to green wavelength range, and the yellow to orange wavelength range. The resulting light emission covers the wavelength ranges from 1000 nm to 1500 nm and from 1000 nm to 2000 nm, and from 1000 nm to 2000 nm.

[0114] For example, the first light-emitting layer 103a (having an emission spectrum with a peak in the blue to blue-green wavelength region) Even if the luminance of the light emitted from the light-emitting diode (which indicates the current density) changes due to deterioration over time or current density, the luminance of the light-emitting diode (which indicates the current density) Since the contribution of the first light-emitting layer 103a to the entire spectrum is about 1 / 4, the chromaticity deviation is relatively small.

[0115] In the above description, the first EL layer 103 emits light in the wavelength range of blue to blue-green and yellow to orange. The second EL layer 107 has an emission spectrum having peaks in both wavelength regions of blue and green. The emission spectrum has peaks in both the green and orange wavelength regions. However, the relationship may be reversed. 107 emits light with peaks in both the blue to blue-green wavelength region and the yellow to orange wavelength region. The first EL layer 103 has a wavelength region of blue-green to green and a wavelength region of orange to red. The emission spectrum may have a peak in both the first and second E The L layer 103 and the second EL layer 107 each have a laminated structure in which layers other than the light-emitting layer are formed. It's okay to have it.

[0116] Next, the present invention relates to a method for producing a light-emitting organic compound which is used in an EL layer of a light-emitting element according to the present embodiment. However, the substance that can be applied to the light-emitting element shown in this embodiment mode is However, the present invention is not limited to these.

[0117] Blue to blue-green light is emitted by, for example, perylene, TBP (abbreviation), 9,10-diphenyl azobenzene, The material is obtained by dispersing a guest material such as anthracene in a suitable host material. In addition, styrylarylene derivatives such as DPVBi (abbreviation) or DNA (abbreviation) ) and t-BuDNA (abbreviation), etc. Polymers such as poly(9,9-dioctylfluorene) may also be used. The optical guest materials are YGA2S (abbreviation) and N,N'-diphenyl-N,N'-biphenyl. Bis(9-phenyl-9H-carbazol-3-yl)stilbene-4,4'-diamine ( In particular, styrylamine derivatives such as YGA2S (abbreviation: PCA2S) are included. ) has a peak at about 450 nm, which is preferable. Anthracene derivatives are preferred, and t-BuDNA (abbreviation) and CzPA (abbreviation) are preferred. In particular, CzPA (abbreviation) is preferable because it is electrochemically stable.

[0118] Blue-green to green light is emitted by coumarin dyes such as coumarin 30 and coumarin 6, F Irpic (abbreviation), Ir(ppy)2(acac) (abbreviation), etc. are used as guest materials. It can be obtained by dispersing it in a suitable host material. n(BTZ)2 (abbreviation), bis(2-methyl-8-quinolinolato)chlorogallium (Ga It can also be obtained from metal complexes such as poly(p-phenylene (mq)2Cl). Polymers such as perylene and TBP (abbreviation) may also be used. It can also be obtained by dispersing it in a suitable host material at a high concentration of t% or more. As a guest material for the red to green light-emitting layer, anthracene derivatives can provide highly efficient light emission. For example, the use of DPABPA (abbreviation) results in highly efficient blue-green emission. In addition, anthracene derivatives with an amino group substituted at the 2-position can emit green light with high efficiency. It is preferable because it can obtain light, and 2PCAPA (abbreviation) is particularly suitable because it has a long life. As the host material, anthracene derivatives are preferable, and the above-mentioned CzPA (abbreviation) is It is preferable because it is electrochemically stable. In addition, it is possible to combine green and blue emission to emit light from blue to red. When fabricating a light-emitting device with two peaks in the green wavelength range, the host for the blue light-emitting layer is Anthracene derivatives with electron transport properties such as CzPA (abbreviation) are used as hosts for the green light-emitting layer. When a hole-transporting aromatic amine compound such as NPB (abbreviation) is used in the This is preferable because light emission is obtained at the interface with the green light-emitting layer. As a host for green emitting materials such as A mixture is preferred.

[0119] Yellow to orange light emission is, for example, rubrene, DCM1 (abbreviation), DCM2 (abbreviation), bis [2-(2-thienyl)pyridinato]acetylacetonatoiridium (Ir(thp)2 (acac)), bis(2-phenylquinolinato)acetylacetonatoiridium (Ir (pq)2(acac)) is used as a guest material and dispersed in an appropriate host material. In particular, a tetracene derivative such as rubrene is used as the guest material. It is preferable because it is highly efficient and chemically stable. In this case, the host material is NPB( Other host materials include aromatic amine compounds such as bis(8-oxophenyl)amine. Bis[2-cinnamoyl-8-quinolinolato] zinc (abbreviation: Znq2) and bis[2-cinnamoyl-8-quinolinolato] zinc Metal complexes such as lead (abbreviation: Znsq2) can be used. A polymer such as alkoxy-1,4-phenylenevinylene may also be used.

[0120] Orange to red light can be emitted from, for example, BisDCM (abbreviation), 4-(dicyanomethylene)-2 ,6-Bis[2-(julolidin-9-yl)ethynyl]-4H-pyran DCM1), 2 -{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[i j]Quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanidine The guest materials are Ir(thp)2(acac) (abbreviation), etc. It is obtained by dispersing it in a suitable host material. It can also be obtained from metal complexes such as poly(3-alkylthio)sq2. Polymers such as BisDC and bis(phenylene) may also be used as guest materials that emit red light. M(abbreviation), DCM2(abbreviation), DCJTI(abbreviation), BisDCJTM(abbreviation) 4H-pyran derivatives are highly efficient and are preferred. In particular, DCJTI (abbreviation), BisD CJTM (abbreviation) is preferred because it has an emission peak near 620 nm.

[0121] In the above-mentioned structure, a suitable host material is a light-emitting material rather than a light-emitting organic compound. It is sufficient that the light color is of short wavelength or has a large energy gap. Specifically, the material is appropriately selected from the hole transport material and the electron transport material typified by the examples shown in the first embodiment. You can also select CBP (abbreviation), TCTA (abbreviation), TCPB (abbreviation), etc. You may also use.

[0122] The light-emitting element shown in this embodiment has an emission spectrum of the first EL layer and an emission spectrum of the second EL layer. As a result of the overlapping of emission spectra, the wavelength ranges from blue to blue-green and blue-green to green are , white light emission that broadly covers the yellow to orange wavelength region and the orange to red wavelength region can be obtained. .

[0123] In addition, by adjusting the thickness of each layer and intentionally causing slight interference of light, it is possible to obtain sharp peaks. The generation of peaks is suppressed, and the emission spectrum is made trapezoidal, resulting in a continuous spectrum. It is also possible to adjust the thickness of each layer to intentionally cause slight interference of light. By changing the position of the peak in the emission spectrum, the position of the peak in the emission spectrum can be changed. The thickness of each layer is adjusted so that the multiple peak intensities that appear are almost the same. By narrowing the interval between the peaks, it is possible to obtain white light with an emission spectrum closer to a trapezoid. can be obtained.

[0124] In this embodiment, the light emitting layers each have a complementary color. By overlapping the different luminescent colors, an EL layer that emits white light is obtained. A specific configuration of an EL layer that emits white light due to the complementary color relationship will be described.

[0125] The EL layer provided in the light-emitting element shown in this embodiment mode is, for example, a layer including a hole-transporting substance and a first a first layer including a light-emitting material, a second layer including a hole-transporting material and a second light-emitting material, and A third layer containing a second light-emitting material and a second electron transport material is laminated in this order from the anode 101. It can be said that it is completed.

[0126] In order to obtain white light emission in the EL layer of the light-emitting element shown in this embodiment, Both the EL material and the second emissive material must emit light. Therefore, the carriers in the EL layer In order to adjust the transport property of the hole transporting material and the electron transporting material, It is preferable that the material used is a hole transporting material or an electron transporting material that can be used in the EL layer. As the transport substance, the substances exemplified in Embodiment 1 can be used as appropriate.

[0127] The first and second luminescent materials have complementary luminescent colors. The quality can be selected and used. The complementary colors are blue and yellow, or blue-green and Examples of materials that emit light in blue, yellow, blue-green, and red include The emission wavelength of the second light-emitting substance may be appropriately selected from the light-emitting substances listed in the first embodiment. By making the wavelength shorter than the emission wavelength of the first luminescent material, the excitation energy of the second luminescent material A part of the energy can be transferred to the first luminescent material, causing the first luminescent material to emit light. Therefore, in the light-emitting element of this embodiment, the emission peak wavelength of the second light-emitting substance is Preferably, the wavelength of the first light-emitting substance is shorter than the emission peak wavelength of the second light-emitting substance.

[0128] The structure of the light-emitting element shown in this embodiment mode is such that light is emitted from a first light-emitting substance and light is emitted from a second light-emitting substance. The first and second luminescent materials have complementary colors. Since the light emitting element has the same structure as that of the first embodiment, white light can be emitted. As a result, a light emitting element with a long life can be obtained.

[0129] Note that the contents described in this embodiment mode may be used in appropriate combination with contents described in other embodiment modes. There can be.

[0130] (Embodiment 6) In this embodiment, one mode of a light-emitting device including the light-emitting element described in any of Embodiments 1 to 5 will be described. This will be explained with reference to Fig. 6. Fig. 6 is a cross-sectional view of the light emitting device.

[0131] In FIG. 6, the light emitting device of the present embodiment includes a substrate 10 and a light emitting element provided on the substrate 10. The light-emitting element 12 has a first electrode 13 and a second electrode 14. Between the electrodes 14 is a layer 15 containing an organic compound. The layer 15 containing an organic compound has n (n is 2 m (m is a natural number, 1≦m≦n-1) EL layers and ( Between the (m+1)th EL layer, there is an electron injection buffer layer in contact with the mth EL layer, and an electron relay layer in contact with the injection buffer layer, an electron relay layer and an (m+1)th EL layer; Each EL layer is provided with at least a light-emitting layer. In addition to the light-emitting layer, a hole injection layer, a hole transport layer, an electron transport layer, or an electron injection layer is appropriately provided. That is, the light-emitting element 12 is the same as the light-emitting element shown in any one of the first to fifth embodiments. The drain region of the transistor 11 and the first electrode 13 are connected to a first interlayer insulating film 16. The wiring 17 penetrates the electrodes 16a, 16b, and 16c, and they are electrically connected to each other. The optical element 12 is separated from another adjacent light emitting element by a partition layer 18. There are.

[0132] In addition, in the transistor 11 shown in FIG. 6, the gate electrode is disposed on the opposite side to the substrate with respect to the semiconductor layer. The transistor 11 is a top-gate type with a gate electrode. There is no particular limitation, and for example, a bottom gate type may be used. The type that has a protective film formed on the semiconductor layer that forms the channel (channel protection type) Alternatively, a part of the semiconductor layer forming the channel may be recessed (channel etch). type) is also acceptable.

[0133] The semiconductor layer of the transistor 11 may be made of silicon (Si) or Group 14 elements in the periodic table, such as ruthenium (Ge), gallium arsenide, and indium Compounds such as phosphorus, and oxides such as zinc oxide and tin oxide, which exhibit semiconducting properties. In addition, the semiconductor layer may have a crystalline structure or an amorphous structure. Either structure may be used.

[0134] Furthermore, oxides that exhibit semiconductor properties (oxide semiconductors) include indium, gallium, A composite oxide of an element selected from aluminum, zinc, and tin can be used. For example, , zinc oxide (ZnO), indium oxide containing zinc oxide (IZO: Indium Zin c Oxide), and oxides consisting of indium oxide, gallium oxide, and zinc oxide (IGZO: Indium Gallium Zinc Oxide) is an example. Specific examples of the semiconductor layer having a crystalline structure include a single crystal semiconductor, a polycrystalline semiconductor, and These are conductors or microcrystalline semiconductors formed by laser crystallization. Alternatively, the material may be formed by crystallization using a solid phase growth method using nickel or the like. It can also be something like that.

[0135] In this specification, a microcrystalline semiconductor is an amorphous semiconductor when the Gibbs free energy is taken into consideration. It belongs to a metastable state between solid and single crystal. A semiconductor with a stable third state, which has short-range order and lattice distortion. Microcrystalline silicon, a typical example of a conductor, has a Raman spectrum that shows the same properties as single-crystal silicon. 20cm -1 That is, the wave number is shifted to the lower wave number side than 520c, which indicates single crystal silicon. m -1 and 480 cm, which indicates amorphous silicon. -1 During this time, Raman spectroscopy of microcrystalline silicon In addition, hydrogen or The halogen content is at least 1 atomic % or more. The inclusion of rare gas elements such as tetragon, krypton, and neon further promotes lattice distortion. Thus, the stability is increased and a good microcrystalline semiconductor layer can be obtained.

[0136] In addition, when the semiconductor layer is made of a material having an amorphous structure, such as amorphous silicon, The transistor 11 and other transistors (which constitute a circuit for driving a light-emitting element) The transistor that performs the function is a light-emitting device having a circuit composed entirely of N-channel transistors. This is because the manufacturing process of the light emitting device is simplified. Zinc (ZnO), indium oxide with zinc oxide (IZO), indium oxide and gallium oxide An oxide made of aluminum and zinc oxide (IGZO) is an N-type semiconductor. A transistor in which these oxides are used for the semiconductor layer is an N-channel type. The device is a circuit that is composed of a single N-channel or P-channel transistor. A light-emitting device having a circuit including both transistors may be used. good.

[0137] Furthermore, the first interlayer insulating films 16a to 16c may be multi-layered as shown in FIGS. 6(A) and 6(C). The first interlayer insulating film 16a may be made of a material such as silicon oxide or silicon nitride. The first interlayer insulating film 16b is made of an inorganic material such as acrylic, siloxane (silicon (Si ) and oxygen (O) form the backbone, and the substituents contain at least hydrogen. The first interlayer is made of a material having self-flatness, such as silicon oxide, which can be applied as a thin film. The insulating film 16c is a silicon nitride film containing argon (Ar). There is no particular limitation on the substance, and substances other than those mentioned here may be used. Layers made of materials other than these may be further combined. 16a to 16c may be formed using both inorganic and organic materials, or inorganic It may be formed using either a thin film or an organic film.

[0138] The partition layer 18 preferably has an edge portion with a continuously changing radius of curvature. The partition layer 18 may be formed using acrylic, siloxane, silicon oxide, or the like. The partition layer 18 may be formed of either an inorganic film or an organic film. Alternatively, it may be formed by using both.

[0139] In addition, in FIGS. 6A and 6C, only the first interlayer insulating films 16a to 16c are formed in the transistor 1. 6B, the first interlayer insulating film is provided between the light emitting element 1 and the light emitting element 12. In addition to 16a to 16c, second interlayer insulating films 19a and 19b may be provided. In the light emitting device shown in FIG. 6B, the first electrode 13 is formed by the second interlayer insulating films 19a and 19b. It penetrates through b and is electrically connected to the wiring 17.

[0140] The second interlayer insulating films 19a and 19b may be multi-layered like the first interlayer insulating films 16a to 16c. The second interlayer insulating film 19a can be formed by coating with acrylic, siloxane, or a single layer. The second interlayer insulating film 19b is made of a material having a self-flatness such as silicon oxide. The silicon nitride film contains argon (Ar). The materials that make up each layer are There is no particular limitation, and materials other than those described here may be used. In this way, the second interlayer insulating film 19a, 19b may be formed by further combining layers made of a material. The film may be formed using both inorganic and organic materials, or may be formed using both inorganic and organic materials. The film may be formed by using either one of the films.

[0141] In the light-emitting element 12, both the first electrode 13 and the second electrode 14 have light-transmitting properties. When the first electrode 1 is made of a material, as shown by the white arrow in FIG. Light can be emitted from both the side of the second electrode 14 and the side of the second electrode 14. When only the light-transmitting material is used, the light-transmitting material is removed. In this way, light can be emitted only from the second electrode 14 side. 13 is made of a material with high reflectivity, or a film (reflective film) made of a material with high reflectivity is the first It is preferable that the first electrode 13 is provided below the first electrode 13. Also, only the first electrode 13 is transparent. When the material is composed of a material having the same properties as the first one, as shown by the white arrow in Figure 6(C), The light emitted can be extracted only from the first electrode 13 side. In this case, the second electrode 14 is a reflector. The second electrode 14 may be made of a material with a high reflectance, or a reflective film may be provided above the second electrode 14. preferable.

[0142] In addition, in the light-emitting element 12, the potential of the second electrode 14 becomes higher than the potential of the first electrode 13. The layer 15 containing an organic compound is laminated so as to operate when a voltage is applied to the layer 15. Alternatively, the potential of the second electrode 14 may be set lower than the potential of the first electrode 13. Even if a layer 15 containing an organic compound is laminated so as to operate when pressure is applied, In the former case, the first electrode 13 is an anode, the second electrode 14 is a cathode, and The transistor 11 is an N-channel transistor. In the latter case, the first electrode 13 is a cathode. The second electrode 14 is an anode, and the transistor 11 is a P-channel transistor. It is.

[0143] As described above, in this embodiment, an amplifier that controls driving of a light-emitting element by a transistor is provided. The active matrix type light emitting device has been described above. A passive matrix type that drives a light-emitting element without providing the element on the same substrate as the light-emitting element. FIG. 7A shows a light-emitting device according to any one of the first to fifth embodiments. FIG. 7(B) is a perspective view of a passive matrix light-emitting device manufactured by applying the semiconductor device. 7(A) is a cross-sectional view taken along dashed line XY in FIG.

[0144] In FIG. 7, a light emitting element 955 is provided between an electrode 952 and an electrode 956 on a substrate 951. The light-emitting element 955 is the light-emitting element described in any of the embodiments 1 to 5. The ends of the electrodes 2 are covered with an insulating layer 953. A partition layer 954 is provided on the insulating layer 953. The side walls of the partition layer 954 are spaced apart from one another as they approach the substrate surface. It is preferable that the partition layer 954 has a slope such that the distance between the partition layer 954 and the side wall becomes narrower. The cross section of the short side direction of the insulating layer 953 is trapezoidal, and the base ( The side in contact with the insulating layer 953) faces in the same direction as the surface direction of the insulating layer 953, and the insulating In this way, the partition layer 954 is provided to prevent static electricity It is possible to prevent defects in the light-emitting element due to the above-mentioned problems. By applying the light-emitting element described in any of Embodiments 1 to 5 to the device, a light-emitting device with low power consumption can be realized. You can get a position.

[0145] The light-emitting device described in this embodiment mode uses the light-emitting element shown as an example in any one of Embodiments 1 to 5. Therefore, the light emitting device can emit light with high luminance and can be driven at a low voltage. The light emitting device has low power consumption.

[0146] (Embodiment 7) In this embodiment, an electronic device including the light-emitting device shown in Embodiment 6 will be described. do.

[0147] The electronic devices of the present embodiment include televisions, video cameras, digital cameras, go-cameras, and Globe-type displays, navigation systems, computers, game devices, mobile information terminals Terminals (mobile computers, mobile phones, portable game consoles, e-books, etc.), recording media An image playback device equipped with a Digital Versatile Disc (DV D) A device equipped with a display unit capable of reproducing a recording medium such as a DVD or the like and displaying the image. Specific examples of these electronic devices are shown in Figure 8.

[0148] FIG. 8A shows an example of a mobile information terminal device 800. The device has a built-in computer and is capable of performing various data processing operations. As a portable information terminal device 800, a PDA (Personal Digital Assistant) sistance) is an example.

[0149] The mobile information terminal device 800 is composed of two housings, a housing 801 and a housing 803. The housing 801 and the housing 803 are foldably connected to each other at a connecting portion 807. The display unit 802 is built into the device 01, and the housing 803 is equipped with a keyboard 805. Of course, the configuration of the mobile information terminal device 800 is not limited to the above, and other accessories may be used. The display unit 802 may be configured as described in any of the first to fifth embodiments. The light emitting element is configured by arranging light emitting elements similar to those described above in a matrix. It has the characteristics of high brightness, low driving voltage, and low power consumption. The display unit 802 formed on the display has the same characteristics, so this portable information terminal device has low power consumption. This is what is being attempted.

[0150] FIG. 8B shows an example of a digital video camera 810 according to this embodiment. The digital video camera 810 has a display unit 812 built into a housing 811, and various other An operation unit is provided. The configuration of the digital video camera 810 is not particularly limited. Other auxiliary equipment may be provided as appropriate.

[0151] In the digital video camera 810, the display unit 812 is the same as that described in the first to fifth embodiments. The light emitting element is configured by arranging light emitting elements similar to those described above in a matrix. The device has the characteristics of low voltage, high brightness and low power consumption. The display unit 812 has similar features, so that the digital video camera 810 has low power consumption. Efforts are being made to reduce power consumption.

[0152] 8C shows an example of a mobile phone 820 according to this embodiment. The device 820 is composed of two housings, a housing 821 and a housing 822, and is connected to a connecting portion 823. The housing 822 is connected so as to be foldable. A display unit 824 is incorporated in the housing 822. The housing 821 is provided with an operation key 825. The present invention is not limited to the above, and other auxiliary equipment may be appropriately provided.

[0153] In the mobile phone 820, the display unit 824 is the same as that described in the first to fifth embodiments. The light emitting element is arranged in a matrix. The light-emitting element has the advantage of being low voltage and consuming little power. The unit 824 also has similar features, so this mobile phone consumes less power. The light emitting diode shown in the above embodiment is used as a backlight for a display provided in a mobile phone or the like. A light emitting element having such a structure may be used.

[0154] FIG. 8D shows an example of a portable computer 830. The electronic device 80 includes a housing 831 and a housing 834 that are connected so as to be openable and closable. A keyboard 833 and the like are provided in a housing 834. The configuration of the computer 830 is not particularly limited, and other auxiliary equipment may be appropriately provided. can be done.

[0155] In the computer 830, the display unit 832 is the same as that described in the first to fifth embodiments. The light emitting element is configured by arranging similar light emitting elements in a matrix. The light-emitting element has the characteristics of low operating voltage and low power consumption. The display unit 832 also has similar features, so this computer consumes less power. .

[0156] FIG. 8E illustrates an example of a television 840. The television 840 has a housing A display unit 842 is built into the 841. The display unit 842 can display images. Also, in this example, a configuration in which the housing 841 is supported by a stand 843 is shown. There are.

[0157] The television 840 can be operated using an operation switch (not shown) provided on the housing 841 or a separate The operation can be performed by the remote control unit 850. The channel and volume can be controlled by using the keys 851, and the display unit 842 displays In addition, the remote control unit 850 can be used to control the image displayed on the remote control unit 850. A display unit 852 for displaying information output from the computer may be provided.

[0158] The television 840 is configured to include a receiver, a modem, and the like. It is possible to receive general television broadcasts, and also to transmit them by wire or wirelessly via a modem. By connecting to a communication network, it is possible to transmit data in one direction (sender to receiver) or two directions (transmit to receive). It is also possible to communicate information between followers and recipients, or between recipients themselves.

[0159] In the television 840, at least one of the display unit 842 and the display unit 852 is The light emitting element is configured by arranging light emitting elements similar to those described in the first to fifth embodiments in a matrix. The light-emitting element has the characteristics of high luminance, low driving voltage, and low power consumption. The display section, which is made up of the light-emitting elements, has the same characteristics.

[0160] As described above, the range of applications of the light-emitting device is extremely wide, and the light-emitting device can be used in electronic devices in various fields. In addition, the light-emitting element shown in any of the embodiments 1 to 5 can be applied to the device. By using a light-emitting device having the above structure, it is possible to provide a display portion that emits light with high luminance and consumes low power. It is therefore possible to provide electronic devices that can

[0161] (Embodiment 8) In this embodiment, a lighting device including the light-emitting device shown in Embodiment 6 will be described. do.

[0162] FIG. 9 is a diagram showing an indoor lighting device. The tabletop lighting device 900 shown in FIG. The lighting portion 901 includes the light-emitting element described in any one of the embodiments 1 to 5. The light-emitting element has the characteristics of high luminance, low driving voltage, and low power consumption. The lighting unit 901, which is made up of the light emitting elements, has the same characteristics, so this table lighting device The device 900 is designed to consume less power. In addition, the light-emitting element can be made large in area. Therefore, it can also be applied as the lighting unit 911 of the ceiling lighting device 910. The light emitting element can be made flexible, so that the lighting unit 9 of the roll-type lighting device 920 can be It is also possible to apply this to 21.

[0163] FIG. 10A is a diagram showing a traffic light. A traffic light 1000 has a green lighting unit 1001 and a yellow lighting unit 1002. The traffic light 1000 has a green, yellow, and red lighting unit 1002 and a red lighting unit 1003. At least one of the corresponding illumination units has the light-emitting element shown in any one of the first to fifth embodiments. Light-emitting elements have the characteristics of high luminance, low driving voltage, and low power consumption. Each lighting section, which is made up of light-emitting elements and corresponds to blue, yellow, and red, has the same characteristics. This unit is designed to consume less power.

[0164] FIG. 10B is a diagram showing an emergency exit guide light. The emergency exit guide light 1010 includes a lighting unit and It can be configured by combining it with a fluorescent plate provided with a fluorescent part. It is composed of a combination of an illumination unit that emits light and a light shielding plate with a transparent part in the shape shown in the drawing. The lighting unit of the emergency exit guide light 1010 may be any of the light emitting devices shown in the first to fifth embodiments. The light-emitting element is applied. The light-emitting element has high luminance, low driving voltage, and low power consumption. The lighting unit, which is made up of the light-emitting element, has the same characteristics. The emergency exit lights are designed to consume less power.

[0165] FIG. 10C is a diagram showing a street lamp. The street lamp includes a support 1021 and a lighting unit 1022. The light-emitting element described in any of the embodiments 1 to 5 is used for the lighting unit 1022. The light-emitting element has the characteristics of high luminance, low driving voltage, and low power consumption. The lighting unit, which is made up of light-emitting elements, also has similar characteristics, making this street light low power consumption. This is what is being attempted.

[0166] As shown in FIG. 10C, power is supplied to the street lamp via a power line 1024 on a utility pole 1023. However, the method of supplying the power supply voltage is not limited to this. For example, a photoelectric conversion device is provided on a support 1021, and a voltage obtained by the photoelectric conversion device is applied to a power supply voltage It can also be used as pressure.

[0167] In addition, an example in which the lighting device is applied to a portable lighting device is shown in FIG. 10(D) and FIG. 10(E). Figure 10(D) shows the configuration of a wearable light, and Figure 10(E) shows the configuration of a handheld light. FIG. 1 is a diagram showing the configuration of

[0168] FIG. 10D is a diagram showing a wearing light. The wearing light has a wearing part 1031 and The illumination unit 1032 is fixed to the mounting unit 1031. The light-emitting element described in any of the embodiments 1 to 5 is used for the lighting unit 1032. The device has the characteristics of high brightness, low driving voltage, and low power consumption. The lighting section, which is made up of elements, has similar characteristics, so this wearable light can consume less power. This is being planned.

[0169] In addition, the configuration of the wearable light is not limited to that shown in FIG. 10(D). For example, the mounting part 1031 may be A ring-shaped flat cord or rubber band is used as a belt, and the lighting unit 1032 is fixed to the belt. It may also be configured to be wrapped directly around the head.

[0170] FIG. 10E is a diagram showing a handheld light. The handheld light has a housing 1041 and The lighting unit 1042 has a switch 1043. The light-emitting elements shown in the above to 5 are applied. The light-emitting elements have high luminance and low driving voltage. The lighting unit 1042, which is made up of the light-emitting elements, is characterized by its low power consumption. With similar features, this handheld light is designed to consume less power.

[0171] The switch 1043 has a function of controlling whether the illumination unit 1042 emits light or not. In addition, the switch 1043 is provided with a function for adjusting the brightness of the illumination unit 1042 when the illumination unit 1042 emits light. It is also possible.

[0172] As described above, the range of applications of the light-emitting device is extremely wide, and the light-emitting device can be used as lighting equipment in a wide range of fields. In addition, the light-emitting element shown in any of the embodiments 1 to 5 can be applied to the above-mentioned device. By using a lighting device having such a structure, it is possible to provide a display section that emits light with high luminance and consumes low power. It is therefore possible to provide a lighting device that can EXAMPLES

[0173] In this example, a light-emitting element which is one embodiment of the present invention will be described with reference to FIG. The chemical formulas of the substances used in the examples and in examples 2 and 3 are shown below.

[0174] [ka]

[0175] The methods for fabricating the light-emitting elements 1 to 4 of this example and the comparative light-emitting element 5 will be described below.

[0176] First, the light-emitting element 1 will be described (see FIG. 11(A)). A first electrode 2101 is formed by depositing indium tin oxide containing silicon by a sputtering method. The film thickness was 110 nm, and the electrode area was 2 mm × 2 mm.

[0177] Next, the first electrode 2101 is formed so that the surface on which the first electrode is formed faces downward. The substrate 2100 is fixed to a substrate holder provided in a vacuum deposition apparatus, and -4 About Pa After the pressure was reduced to 100 MPa, NPB (abbreviation) which is a hole transporting substance and By co-evaporating the acceptor molybdenum (VI) oxide, the organic compound A first charge generating layer 2103a was formed containing a composite material obtained by combining an inorganic compound with The thickness of the film is 50 nm, and the mass ratio of NPB (abbreviation) to molybdenum oxide (VI) is The ratio of NPB to molybdenum oxide was adjusted to 4:1. This is a deposition method in which deposition is performed simultaneously from multiple evaporation sources in one processing chamber.

[0178] Next, NPB (abbreviation: NPB) was deposited on the first charge generating layer 2103a by a deposition method using resistance heating. ) was deposited to a thickness of 10 nm to form a hole transport layer 2103b.

[0179] Furthermore, by co-evaporating CzPA (abbreviation) and 2PCAPA (abbreviation), A light-emitting layer 2103c having a thickness of 30 nm was formed on the transport layer 2103b. The mass ratio of CzPA (abbreviation) and 2PCAPA (abbreviation) is 1:0.05 (=CzPA:2PCAPA The CzPA (abbreviation) is an electron transporting material and the guest material 2PCAPA (abbreviation) is a substance that emits green light.

[0180] Then, Alq (abbreviation) was deposited on the light-emitting layer 2103c by a deposition method using resistance heating. The electron transport layer 2103d was formed to a thickness of 100 nm. A charge generating layer 2103a, a hole transport layer 2103b, a light emitting layer 2103c, and an electron transport layer 21 A first EL layer 2103 containing 03d was formed.

[0181] Next, BPhen (abbreviation) and lithium (Li) were co-deposited to form an electron transport layer. An electron injection buffer layer 2104 having a thickness of 20 nm was formed on the transmission layer 2103d. The mass ratio of BPhen (abbreviation) to lithium (Li) is 1:0.02 (=BPhen:L The results were adjusted to satisfy i).

[0182] Next, PTCBI (abbreviation) and lithium (Li) are co-deposited to perform electron injection. An electron relay layer 2105 having a thickness of 3 nm was formed on the input buffer layer 2104. The mass ratio of PTCBI (abbreviation) to lithium (Li) is 1:0.02 (=PTCBI:L i). The LUMO level of PTCBI (abbreviation) is cyclic boron. The results of CV measurements indicate that the potential is approximately -4.0 eV.

[0183] Next, on the electron relay layer 2105, NPB (abbreviation) which is a hole transporting substance and an acceptor The second charge generating layer was formed by co-evaporating molybdenum(VI) oxide, a carbon material. The thickness of the film was 60 nm, and it was made of NPB (abbreviation) and molybdenum oxide (VI ) was adjusted to a mass ratio of 4:1 (=NPB:molybdenum oxide).

[0184] Next, a second EL layer 2107 was formed on the second charge generating layer 2106. The method is as follows: first, NPB ( abbreviation) was deposited to a thickness of 10 nm to form a hole transport layer 2107a.

[0185] Then, CzPA (abbreviation) and 2PCAPA (abbreviation) are co-deposited to form a hole A light-emitting layer 2107b having a thickness of 30 nm was formed on the transport layer 2107a. The mass ratio of CzPA (abbreviation) and 2PCAPA (abbreviation) is 1:0.05 (=CzPA:2PCAPA That is, the light-emitting layer 2107b included in the second EL layer 2107 was adjusted to be , has the same configuration as the light-emitting layer 2103 c included in the first EL layer 2103 .

[0186] Next, on the light-emitting layer 2107b, Alq (abbreviation) was deposited to a thickness of 10 nm, and then BPhen ( The electron transport layer 2107c was formed by depositing 20 nm of ZnO (abbreviation: ZnO). Lithium fluoride (LiF) is deposited on the transport layer 2107c to a thickness of 1 nm. Thus, the hole transport layer 2107a and the light emitting layer 2107 b. forming a second EL layer 2107 including an electron transport layer 2107c and an electron injection layer 2107d; Ta.

[0187] Finally, aluminum (Al ) to a thickness of 200 nm to form a second electrode 2102. Thus, the light-emitting element 1 was fabricated.

[0188] Next, the light-emitting element 2 will be described. The light-emitting element 2 has a light-emitting layer other than the electron relay layer 2105. The light-emitting element 2 was fabricated in the same manner as the light-emitting element 1. Therefore, in this example, the light-emitting element 2 except for the electron-relay layer 2105 is The structure and manufacturing method of the light-emitting element 2 are described above. The electron relay layer 2105 is made of PPDN (abbreviation) which is an electron transporting material and ZnO which is a donor material. By co-evaporating lithium (Li) on the electron injection buffer layer 2104, 3 An electron relay layer 2105 having a thickness of 1 nm was formed. The mass ratio of P to Li was adjusted to 1:0.02 (=PPDN:Li). The LUMO level of PDN (abbreviation) is - It is about 3.83 eV.

[0189] Next, the light-emitting element 3 will be described. The light-emitting element 3 has a light-emitting layer other than the electron relay layer 2105. The light-emitting element 3 was fabricated in the same manner as the light-emitting element 1. Therefore, in this example, the light-emitting element 3 except for the electron-relay layer 2105 The structure and manufacturing method of the light-emitting element 3 are described above. The electron relay layer 2105 is made of an electron transport material, PTCBI (abbreviation), and a donor material, The electron injection buffer layer 210 is formed by co-evaporating lithium oxide (LiO) An electron relay layer 2105 having a thickness of 3 nm was formed on the silicon substrate 4. The mass ratio of PTCBI to lithium oxide (Li2O) is 1:0.02 (=PTCBI:Li2O). It was adjusted so that

[0190] Next, the light-emitting element 4 will be described. The light-emitting element 4 has a light-emitting layer other than the electron relay layer 2105. The light-emitting element 4 was fabricated in the same manner as the light-emitting element 1. Therefore, the light-emitting element 4 except for the electron-relay layer 2105 was fabricated in the same manner as the light-emitting element 1. The structure and manufacturing method of the light-emitting element 4 are described above. The electron relay layer 2105 is made of PPDN (abbreviation) which is an electron transporting material and ZnO which is a donor material. The electron injection buffer layer 2104 is formed by co-evaporating lithium oxide (Li2O) An electron relay layer 2105 having a thickness of 3 nm was formed on the substrate. The mass ratio of PPDN to lithium fluoride (Li2O) was 1:0.02 (=PPDN:Li2O). was adjusted to.

[0191] Next, the comparative light-emitting element 5 will be described (see FIG. 11(B)). This is a structure in which the electronic relay layer 2105 is removed from the optical elements 1 to 4, and the other layers are The comparative light-emitting element 5 was formed by the same method as that for the light-emitting elements 1 to 4. After the electron injection buffer layer 2104 is formed, a first Thus, a comparative light-emitting element 5 of this example was obtained.

[0192] Table 1 below shows the element structures of the light-emitting elements 1 to 4 and the comparative light-emitting element 5.

[0193] [Table 1]

[0194] The thus obtained light-emitting elements 1 to 4 and the comparative light-emitting element 5 were placed in a globe box in a nitrogen atmosphere. After sealing each light-emitting element in the box so that it is not exposed to the atmosphere, The operating characteristics of the light-emitting device were measured. The measurements were performed at room temperature (25°C). The experiment was conducted in an atmospheric condition.

[0195] FIG. 12 shows the voltage-luminance characteristics of the light-emitting elements 1 to 4 and the comparative light-emitting element 5. The horizontal axis represents the applied voltage (V) and the vertical axis represents the luminance (cd / m 2 ) and also represents the light FIG. 13 shows the voltage-current density characteristics of the elements 1 to 4 and the comparative light-emitting element 5. The horizontal axis represents voltage (V) and the vertical axis represents current density (mA / cm 2 ) and the brightness of each light-emitting element. The brightness is 1000cd / m 2 The voltages when the voltage is in the vicinity are shown in Table 2 below.

[0196] [Table 2]

[0197] As shown in FIG. 12, the light-emitting elements 1 to 4 provided with the electron-relay layer have a higher As shown in FIG. 13, the luminescence of the EL element having the electron relay layer is high. It can be seen that the elements 1 to 4 have a higher current density than the comparative light-emitting element 5.

[0198] As a result, the light-emitting elements 1 to 4 of this embodiment were able to obtain the characteristics as light-emitting elements and function sufficiently. In addition, as shown in Table 2, the light-emitting elements 1 to 4 have a higher It was confirmed that the light-emitting element can be driven at a low voltage. EXAMPLES

[0199] In this example, a light-emitting element which is one embodiment of the present invention will be described with reference to FIG. In the light-emitting element and the comparative light-emitting element shown in this embodiment, the light-emitting element described in Example 1 was The above description will be used for the passing portion.

[0200] The methods for fabricating the light-emitting elements 6 to 9 of this example and the comparative light-emitting element 10 will be described below.

[0201] First, the light-emitting element 6 will be described (see FIG. 11(A)). The light-emitting element 6 of this embodiment is Except for the electron injection buffer layer 2104, the light-emitting device was fabricated in the same manner as in the light-emitting device 1 shown in Example 1. Therefore, the configuration and manufacturing method of the light-emitting element 6 other than the electron injection buffer layer 2104 will be described here. The description of the first embodiment is incorporated herein. In the light-emitting device 6 of this embodiment, The electron transport material BPhen (abbreviation) and the donor material lithium oxide (Li2 O) was co-evaporated to form an electron injection barrier layer having a thickness of 20 nm on the electron transport layer 2103d. A buffer layer 2104 was formed using BPhen (abbreviation) and lithium oxide (LiO The mass ratio of BPhen:LiO was adjusted to 1:0.02 (=BPhen:LiO).

[0202] Next, the light-emitting device 7 will be described. The light-emitting device 7 of this embodiment is The light-emitting element 2 was fabricated in the same manner as in Example 1 except for the layer 2104. The configuration and manufacturing method of the light emitting element 7 other than the electron injection buffer layer 2104 are described in Example 1. In the light-emitting device 7 of this embodiment, the electron transporting material The BPhen (abbreviation) and lithium oxide (Li2O), which is a donor material, are co-evaporated. As a result, an electron injection buffer layer 2104 having a thickness of 20 nm is formed on the electron transport layer 2103d. The mass ratio of BPhen (abbreviation) to lithium oxide (Li2O) was 1: The ratio was adjusted to 0.02 (=BPhen:Li2O).

[0203] Next, the light-emitting device 8 will be described. The light-emitting device 8 of this embodiment is The light-emitting element 3 was fabricated in the same manner as in Example 1 except for the layer 2104. The configuration and manufacturing method of the light emitting element 8 other than the electron injection buffer layer 2104 are described in Example 1. In the light-emitting device 8 of this embodiment, the electron transporting material The BPhen (abbreviation) and lithium oxide (Li2O), which is a donor material, are co-evaporated. As a result, an electron injection buffer layer 2104 having a thickness of 20 nm is formed on the electron transport layer 2103d. The mass ratio of BPhen (abbreviation) to lithium oxide (Li2O) was 1: The ratio was adjusted to 0.02 (=BPhen:Li2O).

[0204] Next, the light-emitting device 9 will be described. The light-emitting device 9 of this embodiment has an electron injection buffer The layers other than the layer 2104 were fabricated in the same manner as in the light-emitting element 4 shown in Example 1. The configuration and manufacturing method of the light emitting element 9 other than the electron injection buffer layer 2104 are described in Example 1. In the light-emitting element 9 of this embodiment, the electron transporting material The BPhen (abbreviation) and lithium oxide (Li2O), which is a donor material, are co-evaporated. As a result, an electron injection buffer layer 2104 having a thickness of 20 nm is formed on the electron transport layer 2103d. The mass ratio of BPhen (abbreviation) to lithium oxide (Li2O) was 1: The ratio was adjusted to 0.02 (=BPhen:Li2O).

[0205] Next, the comparative light-emitting element 10 will be described (see FIG. 11(B)). The structure is such that the electronic relay layer 2105 is omitted from the light-emitting elements 6 to 9, and the other layers are The comparative light-emitting element 10 was fabricated in the same manner as the light-emitting elements 6 to 9. In this case, after forming the electron injection buffer layer 2104, In this way, the comparative light-emitting element 10 of this example was manufactured. Got it.

[0206] Table 3 below shows the element structures of the light-emitting elements 6 to 9 and the comparative light-emitting element 10.

[0207] [Table 3]

[0208] The light-emitting elements 6 to 9 and the comparative light-emitting element 10 thus obtained were placed in a globe box in a nitrogen atmosphere. After sealing each light-emitting element in the box so that it is not exposed to the atmosphere, The operating characteristics of these light-emitting devices were measured. The measurements were performed at room temperature (25°C). I went there for the atmosphere.

[0209] FIG. 14 shows the voltage-luminance characteristics of the light-emitting elements 6 to 9 and the comparative light-emitting element 10. The horizontal axis is the applied voltage (V) and the vertical axis is the luminance (cd / m 2 ) and also represents the light FIG. 15 shows the voltage-current density characteristics of the elements 6 to 9 and the comparative light-emitting element 10. The horizontal axis represents voltage (V) and the vertical axis represents current density (mA / cm 2 ) for each light-emitting element. Brightness is 1000cd / m 2 The voltages when the voltage is in the vicinity are shown in Table 4 below.

[0210] [Table 4]

[0211] As shown in FIG. 14, the light-emitting elements 6 to 9 provided with the electron-relay layer have a higher As shown in Fig. 15, the emission layer with the electron relay layer is It can be seen that the optical elements 6 to 9 have a higher current density than the comparative light-emitting element 10.

[0212] As a result, the light-emitting elements 6 to 9 of this embodiment were able to obtain the characteristics required for a light-emitting element and function satisfactorily. It was confirmed that the light-emitting elements 6 to 9 can be driven at a low voltage. It was confirmed that... EXAMPLES

[0213] In this example, a light-emitting element which is one embodiment of the present invention will be described with reference to FIG. In the light-emitting element and the comparative light-emitting element shown in this embodiment, the light-emitting element described in Example 1 was The above description will be used for the passing portion.

[0214] A method for fabricating the light-emitting element 11 of this example and the comparative light-emitting element 12 will be described below.

[0215] First, the light emitting element 11 will be described (see FIG. 11(A)). The electron transport layer 2103d of the first EL layer 2103 and the electron injection buffer layer 2104 are The other components were fabricated in the same manner as in the light-emitting device 1 shown in Example 1. Regarding the configuration and manufacturing method of the light emitting element 11 other than the layer 103d and the electron injection buffer layer 2104, The description of the first embodiment is incorporated herein for the description of the light emitting device 11 of this embodiment. On the optical layer 2103c, Alq (abbreviation) is deposited to a thickness of 10 nm, and then BPhen (abbreviation) is deposited to a thickness of 20 nm. The electron transport layer 2103d was formed by depositing 1 nm of the Lithium oxide (Li2O) is deposited on the layer 2103d to a thickness of 0.1 nm, thereby forming an electron injection layer. An input buffer layer 2104 was then formed. In this manner, the light-emitting device 11 of this example was obtained.

[0216] Next, the comparative light-emitting element 12 will be described (see FIG. 11(B)). The element 12 has a structure in which the electron relay layer 2105 is removed from the light-emitting element 11, and the other layers The comparative light-emitting element 12 was formed by the same method as that for the light-emitting element 11. After the electron injection buffer layer 2104 is formed, a first Thus, a comparative light-emitting element 12 of this example was obtained.

[0217] Table 5 below shows the element structures of the light-emitting element 11 and the comparative light-emitting element 12.

[0218] [Table 5]

[0219] The light-emitting element 11 and the comparative light-emitting element 12 obtained above were placed in a glove box in a nitrogen atmosphere. After sealing each light-emitting element in the chamber to prevent it from being exposed to the atmosphere, The operating characteristics of the light-emitting element were measured. The measurements were performed in an atmosphere maintained at room temperature (25°C). I went there with a feeling of excitement.

[0220] FIG. 16 shows the voltage-luminance characteristics of the light-emitting element 11 and the comparative light-emitting element 12. , the horizontal axis is the applied voltage (V), and the vertical axis is the luminance (cd / m 2 ) is also represented. The voltage-current density characteristics of the light-emitting element 11 and the comparative light-emitting element 12 are shown in FIG. The vertical axis represents voltage (V), and the vertical axis represents current density (mA / cm 2 ) Also, the brightness of each light-emitting element is 1 000cd / m 2 The voltages when the voltage is in the vicinity are shown in Table 6 below.

[0221] [Table 6]

[0222] As shown in FIG. 16, the light-emitting element 11 provided with the electron-relay layer has a higher efficiency than the comparative light-emitting element 12. It can be seen that high brightness can be obtained. It can be seen that the light emitting element 11 has a higher current density than the comparative light emitting element 12.

[0223] As a result, the light emitting device 11 of this embodiment has the characteristics required for a light emitting device and functions satisfactorily. It was also confirmed that the light-emitting element 11 can be driven at a low voltage. I was able to acknowledge it. [Explanation of symbols]

[0224] 10 Substrate 11 Transistor 12 Light emitting element 13 electrodes 14 electrodes 15 Layer containing organic compounds 16a Interlayer insulating film 16b Interlayer insulating film 16c Interlayer insulating film 17 Wiring 18 Partition layer 19a Interlayer insulating film 19b Interlayer insulating film 101 Anode 102 Cathode 103 EL layer 103a First light-emitting layer 103b Second light-emitting layer 104 Electron injection buffer layer 105 Electronic Relay Layer 106 Charge generation layer 106a Layer containing a hole transporting material 106b Layer containing an acceptor material 107 EL layer 107a Third light-emitting layer 107b Fourth light-emitting layer 108 Electron transport layer 111 Fermi level of anode 112 Fermi level of cathode 113 LUMO level of the first EL layer 114 Donor Levels of Donor Materials in Electron Relay Layers 115 LUMO Levels of Electron Transporting Materials in Electron Relay Layers 116 Acceptor Levels of Acceptor Materials in Charge Generation Layers 117 LUMO level of the second EL layer 330 First Emission 340 Second Emission 800 Portable information terminal equipment 801 Case 802 Display section 803 Case 805 Keyboard 807 Connection section 810 Digital Video Camera 811 Case 812 Display section 820 Mobile Phones 821 Case 822 Case 823 Connection section 824 Display section 825 Operation Key 830 Computer 831 Case 832 Display section 833 Keyboard 834 Case 840 Television 841 Case 842 Display section 843 Stand 850 Remote Controlled Device 851 Operation key 852 Display section 900 Tabletop Lighting Device 901 Lighting Department 910 Ceiling lighting equipment 911 Lighting Department 920 Roll-type lighting device 921 Lighting Department 951 Board 952 Electrode 953 Insulation Layer 954 Partition layer 955 Light emitting element 956 Electrode 1000 Traffic Lights 1001 Lighting Department 1002 Lighting Department 1003 Lighting Department 1010 Evacuation exit guide light 1021 Support 1022 Lighting Department 1023 Electric pole 1024 Power Lines 1031 Mounting part 1032 Lighting Department 1041 Case 1042 Lighting Department 1043 Switch 2100 Board 2101 Electrode 2102 Electrode 2103 EL layer 2103a Charge generation layer 2103b Hole transport layer 2103c Emitting layer 2103d Electron transport layer 2104 Electron injection buffer layer 2105 Electronic Relay Layer 2106 Charge generation layer 2107 EL layer 2107a Hole transport layer 2107b Light-emitting layer 2107c Electron transport layer 2107d Electron injection layer

Claims

[Claim 1] The device has n (n is a natural number of 2 or more) EL layers between an anode and a cathode, Between the m-th (m is a natural number, 1≦m≦n−1) EL layer and the m+1-th EL layer from the anode, a first layer in contact with the m-th EL layer and including a first donor material; a second layer in contact with the first layer, the second layer including an electron transporting material and a second donor material; a third layer which is in contact with the second layer and the (m+1)th EL layer and contains a hole transporting substance and an acceptor substance;

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