Light-emitting element

Abstract

To provide a light-emitting element with a micro-cavity structure which is capable of amplifying a plurality of wavelengths to give emission of a desired color.SOLUTION: A light-emitting element includes a pair of electrodes and an EL layer held between the pair of electrodes. One of the pair of electrodes is a reflection electrode forming a reflection surface. The other of the pair of electrodes is an electrode forming a half-reflection surface. When the optical distance between the reflection surface and the half-reflection surface is L and the wavelength component of the light emitted from the light-emitting element is λ, the number of λ satisfying L=nλ / 2 (n is an integer of 2 or more) is two or more.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] In recent years, light-emitting devices that have a light-emitting layer (hereinafter also referred to as an EL layer) containing an organic compound between a pair of electrodes have been developed. The development of electroluminescent elements (also called electroluminescent elements: EL elements) is currently underway. One of the areas that is attracting attention as an application of EL is the lighting field. Lighting devices using these elements can be made thin and lightweight, and can emit light from a surface, etc. One of the features of this lighting fixture is that it has features that are not available in conventional lighting fixtures.

[0003] In addition, EL elements have a high efficiency in converting electricity into light, and therefore have great potential for energy saving performance. In addition, depending on the substrate selected, flexible lighting can be realized. We can provide lighting equipment that is highly resistant to physical damage and impacts, and extremely lightweight lighting equipment. It is also notable that

[0004] The Japanese Industrial Standards (JIS) define the color of lighting according to its correlated color temperature. From the lowest temperature incandescent light to the highest color temperature daylight, the color range is 2600K to 7100K. The light with a low temperature is specified as indoor lighting. EL elements can be used to However, the light expressed by these color temperatures generally has the following characteristics: It is light with a wide wavelength, and while obtaining light that meets the standards from a single luminous substance, At the same time, it is very difficult to obtain the brightness and reliability required for lighting. EL elements that can express good white color using multiple luminescent materials with different emission wavelengths are being considered. (See, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2007-53090 A Summary of the Invention [Problem to be solved by the invention]

[0006] The light emitted from the light-emitting element travels several kilometers before it leaves the element. At this time, the light is reflected by layers with different refractive indices or at the interface with a material with a high reflectivity. Then, a reflex occurs.

[0007] By repeatedly reflecting light, certain wavelengths of light are strengthened. This is called a microcathode. Microcavities can have a significant effect on the optical properties of certain wavelengths of light. Therefore, this phenomenon is actively used for displays that require high color purity. However, in an EL device with an EL layer of normal thickness, the microcavity structure is a single-mode It can only enhance one wavelength of light and does not cover the entire visible light range. However, it was difficult to apply this technology to lighting devices that required this technology.

[0008] Therefore, in the present invention, in a light emitting device having a microcavity structure, The objective of the present invention is to provide a light-emitting element capable of amplifying a desired light emission color. The subject is.

[0009] Another object of the present invention is to provide a light-emitting element that is suitable for use in lighting applications.

[0010] Another object of the present invention is to provide a lighting device having a color temperature suitable for lighting purposes. Another object of the present invention is to provide a lighting device with low power consumption.

[0011] The present invention has only to solve at least one of the above problems. [Means for solving the problem]

[0012] The present inventors have found that by setting the optical thickness of the EL element to a certain value or more, light of multiple wavelengths can be emitted. It has been found that it is possible to form a resonant structure in the above-mentioned manner, and thus the above-mentioned object can be achieved. That is, one embodiment of the present invention is a light-emitting device having a pair of electrodes and an EL layer sandwiched between the pair of electrodes. In the light-emitting device, one of the pair of electrodes is a reflective electrode that forms a reflective surface, The other of the pair of electrodes is an electrode that forms a semi-reflective surface, and the EL layer contains a light-emitting material. If the optical distance between the reflecting surface and the semi-reflecting surface is L, the emission wavelength range of the light emitting element is The wavelength λ in the range satisfies L=nλ / 2 (n is an integer of 2 or more). That is, the light emitting element has an emission spectrum of the luminescent material of L=nλ The optical length L is set to cover at least two wavelengths λ satisfying the relation:

[0013] Another aspect of the present invention is a device having a pair of electrodes and an EL layer sandwiched between the pair of electrodes. In the light-emitting device, one of the pair of electrodes is a reflective electrode that forms a reflective surface, The other electrode is an electrode forming a semi-reflective surface, and the EL layer is at least a red light emitting layer. a blue light-emitting layer and a thickness adjusting layer; The optical distance of the resonant structure is 650 nm to 1500 nm. It is a light emitting element.

[0014] Another aspect of the present invention is a device having a pair of electrodes and an EL layer sandwiched between the pair of electrodes. In the light-emitting device, one of the pair of electrodes is a reflective electrode that forms a reflective surface, The other electrode is an electrode forming a semi-reflective surface, and the EL layer is at least a red light emitting layer. a green light emitting layer, a blue light emitting layer, and a thickness adjusting layer; and the optical distance of the resonant structure formed by the semi-reflective surface is 650 nm to 1500 nm. The light-emitting element is characterized in that

[0015] Another aspect of the present invention is a device having a pair of electrodes and an EL layer sandwiched between the pair of electrodes. In the light-emitting device, one of the pair of electrodes is a reflective electrode that forms a reflective surface, The other electrode is an electrode forming a semi-reflective surface, and the EL layer is at least a red light emitting layer. a green light emitting layer, a blue light emitting layer, and a thickness adjusting layer; and the optical distance of the resonant structure formed by the semi-reflective surface is 1200 nm to 1400 nm. The light-emitting device is characterized in that

[0016] In another aspect of the present invention, in the above-mentioned configuration, the blue light-emitting layer has an emitting wavelength of 430 nm to 495 nm. The red light-emitting layer has an emission peak at 590 nm to 700 nm. The light emitting device is characterized by the above.

[0017] In another aspect of the present invention, in the above-mentioned configuration, the green light-emitting layer has a wavelength of 495 nm to 560 nm. The light-emitting element is characterized by having an emission peak.

[0018] In another aspect of the present invention, in the above-mentioned configuration, the electrode forming the semi-reflective surface is a thin metal film. The light-emitting device is characterized in that

[0019] Another aspect of the present invention is the above-mentioned configuration, wherein the electrode forming the semi-reflective surface has light-transmitting properties. The light-emitting element is characterized in that the electrode is made of a conductive metal oxide.

[0020] In another aspect of the present invention, in the above-mentioned configuration, the electrode forming the semi-reflective surface is a thin metal film and a transparent film. A light-emitting device characterized in that the electrode is made of a laminate with a conductive metal oxide having optical properties. It is.

[0021] In another aspect of the present invention, in the above-mentioned structure, a film thickness adjusting layer is provided in contact with the reflective electrode. The light-emitting element is characterized in that

[0022] In another aspect of the present invention, in the above-mentioned configuration, the EL layer is at least one of the light-emitting layers. The light-emitting units are each formed of a charge generating layer. The light-emitting element is characterized in that the light-emitting elements are separated from each other.

[0023] In another aspect of the present invention, in the above-mentioned configuration, at least a part of the charge generating layer has the thickness The light-emitting device is characterized by also serving as an adjustment layer.

[0024] In another aspect of the present invention, in the above-mentioned structure, the film thickness adjusting layer is made of a conductive gold having light transmitting properties. A metal oxide or an organic compound having carrier transport properties and an acceptor or non-acceptor of the organic compound. The material is preferably a composite material with a substance exhibiting donor properties, or both. The light-emitting device is characterized by the above.

[0025] In another aspect of the present invention, in the above-mentioned structure, the composite material is an organic compound having a high hole transporting property. and a composite material having an acceptor property for the organic compound. It is an element.

[0026] In another aspect of the present invention, in the above-mentioned structure, the substance exhibiting acceptor properties is a transition metal The light-emitting element is characterized in that the oxide is

[0027] In another aspect of the present invention, in the above-mentioned configuration, the oxide of the transition metal is a molybdenum oxide. The light-emitting element is characterized in that:

[0028] In another aspect of the present invention, the light-emitting element according to the above aspect is provided with a seal between a support substrate and a sealing substrate. The light emitting device is encapsulated in a plastic material.

[0029] According to another aspect of the present invention, in the above-mentioned configuration, the light emitting element is supported on the reflective electrode side. The light emitting device is characterized in that it is fixed to a substrate.

[0030] In another aspect of the present invention, in the above-mentioned configuration, the support substrate is made of a material having high thermal conductivity. A light-emitting device characterized in that the structure is made of a material having a high thermal conductivity. be.

[0031] In another aspect of the present invention, in the above-mentioned configuration, the material having high thermal conductivity is aluminum. , duralumin, stainless steel, or a laminate of these. It is a light-emitting device.

[0032] Another aspect of the present invention is the above-mentioned configuration, further comprising a surface of the semi-transmissive semi-reflective electrode in contact with the EL layer. The opposite surface is covered with a transparent film having a refractive index of 1 to 2.3. The light emitting device is characterized by the above.

[0033] According to another aspect of the present invention, in the above-mentioned configuration, The device is characterized in that a member for diffusing light is provided on the outer side of the substrate on the electrode side that forms the semi-reflective surface. This is a light emitting device.

[0034] Another aspect of the present invention is a lighting device including the light emitting device according to the above configuration. Effect of the Invention

[0035] The light-emitting device of the present invention has a microcavity structure and is resistant to light of multiple wavelengths. It is a light-emitting element that can obtain an amplification effect and can emit light of a desired color. .

[0036] The lighting device of the present invention has a color temperature suitable for lighting purposes and consumes little power. It is a bright device. [Brief description of the drawings]

[0037] [Figure 1] FIG. 1 is a conceptual diagram illustrating a structure of a light-emitting element according to one embodiment of the present invention. [Diagram 2] FIG. 1 is a conceptual diagram illustrating a structure of a light-emitting element according to one embodiment of the present invention. [Diagram 3] 1 illustrates a lighting device according to one embodiment of the present invention. [Figure 4] 1 illustrates a lighting device according to one embodiment of the present invention. [Diagram 5] 1 illustrates a lighting device according to one embodiment of the present invention. [Figure 6] FIG. 13 shows luminance-current density characteristics of the light-emitting element 1. [Figure 7] FIG. 13 shows luminance-voltage characteristics of the light-emitting element 1. [Figure 8] FIG. 13 shows current efficiency vs. luminance characteristics of the light-emitting element 1. [Figure 9]FIG. 2 shows current-voltage characteristics of the light-emitting element 1. [Figure 10] FIG. 2 shows an emission spectrum of the light-emitting element 1. [Figure 11] CIE chromaticity coordinate diagram of light-emitting element 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] Hereinafter, the embodiment of the present invention will be described with reference to the drawings. However, the present invention is not limited to the above-mentioned embodiments, and may be practiced in various different ways without departing from the spirit and scope of the present invention. It will be easily understood by those skilled in the art that the form and details of the present invention may be modified in various ways. Therefore, it should not be construed as being limited to the description of this embodiment mode.

[0039] In addition, the figures used for explanation are for ease of understanding, and the enlargement and reduction ratios of each element are constant. Therefore, the thickness, length, and size ratios of each element in the drawings are the same as those of the present invention. Please note that the thickness, length, and size ratios of the light emitting device of the embodiment are not shown. .

[0040] In addition, if the numbers are the same and only the alphabetical symbols are different, In some cases, the above-mentioned symbols may be treated as a group. This refers to the group including all the different symbols of FUFABET.

[0041] (Embodiment 1) 1A and 1B are schematic cross-sectional views of a light-emitting element according to one embodiment of the present invention. The light-emitting element described in the above embodiment has an EL layer sandwiched between a pair of electrodes. The light-emitting layer is composed of a plurality of separate layers and emits light when a current flows through it. include.

[0042] FIG. 1A will be described. One of a pair of electrodes (a first electrode 101 and a second electrode 102) is a positive electrode. One is the electrode, the other is the cathode. Also, one is a reflector made of a material with high reflectivity for visible light. The electrode is a semi-transparent material that transmits some of the visible light and reflects some of it. The reflective and semi-reflective surfaces that make up the resonant structure 106 are the EL layer of the reflective electrode. The surface on the EL layer 103 side and the surface on the EL layer 103 side of the semi-transparent semi-reflective electrode are shown in FIG. The light-emitting device has a pair of electrodes that is composed of a reflective electrode and a semi-transparent semi-reflective electrode. Thus, a resonant structure 106 is formed between the upper surface of the reflective electrode and the lower surface of the semi-transparent semi-reflective electrode. A light emitting device having a microcavity structure in which light of a wavelength may be amplified or attenuated. Becomes an element.

[0043] In this case, the semi-transparent semi-reflective electrode is usually used as a transparent electrode because it is made of metal. It has higher conductivity than transparent conductive films such as indium tin oxide (ITO), and is less susceptible to voltage drop. The luminance unevenness in the light-emitting surface can be reduced. This can more effectively suppress the voltage drop and eliminate the unevenness of the brightness. In FIG. 1(A), the first electrode 101 is an anode and The first electrode 101 is a reflective electrode, and the second electrode 102 is a cathode and a semi-transparent semi-reflective electrode. These combinations and hierarchical relationships can be freely combined, but the top emitter The application to silicon structures is particularly suitable.

[0044] The EL layer 103 is formed by applying a voltage between the first electrode 101 and the second electrode 102. Any structure may be used as long as it can emit light by the resonance. At least one of the structures 106 that satisfies L=nλ / 2 (n is an integer of 2 or more) for the optical distance L of the structure 106 It has a light-emitting layer that emits light at two wavelengths λ. In the case of FIG. 1(A), the light-emitting layer 10 The light emitting layer 104 has two light emitting layers, ie, the light emitting layer 105 and the light emitting layer 106. The light emitting layer 105 emits light having a wavelength λ1 that satisfies L=2×λ1 / 2 with respect to the optical distance L. In the figure, an example is shown in which light having a wavelength λ2 that satisfies L=3×λ2 / 2 is emitted.

[0045] The EL layer 103 is a red light emitting layer that emits light in a wavelength range recognized as red light emission, and a blue light emitting layer that emits light in a wavelength range recognized as blue light emission. It is preferable that the light emitting layer further includes a blue light emitting layer that emits light in a wavelength range recognized by the color filter. It is more preferable that the optical element has a green light-emitting layer that emits light in a wavelength range that can be recognized. The layer may be a light-emitting layer that emits a plurality of colors, for example red and blue. The red and blue light-emitting layers are replaced by a single light-emitting layer having light emission in both wavelength regions. It is possible to do so.

[0046] The optical distance L of the resonant structure 106 in FIG. 1(A) is 650 nm or more and 1500 nm or less. The optical distance is determined by adding the thickness of each film present in the resonant structure 106 to the length of the film. The refractive index is the sum of the refractive indices

[0047] In this specification, the light emitted by the blue light-emitting layer has an emission peak at 430 nm to 495 nm. The light emitted by the green light-emitting layer has an emission peak at 495 nm to 560 nm. The light emitted by the red light-emitting layer has an emission peak at 590 nm to 700 nm. It is assumed that the light has a wavelength of 1000 nm or more.

[0048] Here, the EL layer 103 has a thickness adjusting layer. The optical thickness of the EL layer of the element is 650nm to 1500nm, which is lower than that of a conventional light-emitting element. This results in a very thick-film light-emitting element. Therefore, it is necessary to use only organic compounds that are commonly used. Therefore, when a light-emitting device with this thickness is fabricated, the driving voltage increases significantly. By using a thickness adjustment layer, the film thickness can be increased without causing a large increase in the driving voltage. This realizes adjustment of the film thickness of the light emitting element in this embodiment.

[0049] The thickness adjusting layer can be made of a metal oxide having light-transmitting properties. The metal oxides that can be used are indium oxide (In2O3), tin oxide (SnO2), and zinc oxide. Lead (ZnO), ITO, indium zinc oxide (In2O3-ZnO), or any of these In addition, the metal oxide material containing silicon oxide is also suitable. and a substance that exhibits acceptor or donor properties with respect to the substance with high carrier transport properties. A composite material film composed of a material and a film thickness adjusting layer can also be suitably used as the film thickness adjusting layer.

[0050] A carrier transporting substance and a compound that exhibits acceptor or donor properties with respect to the carrier transporting substance. The composite material composed of a material with high hole transport properties and a material with high acceptor properties is A composite material composed of a substance having high electron transport properties and a substance having high electron transport properties They can be broadly divided into composite materials composed of substances that exhibit donor properties and materials that exhibit donor properties.

[0051] First, a material having a high hole transporting property and a material having an acceptor property to the material having a high hole transporting property are used. This article describes the composite materials that are used.

[0052] The acceptor material for the composite material can be 7,7,8 ,8-Tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TC NQ), chloranil, etc. Also, oxides of transition metals, particularly those of the periodic table, Examples of the oxides of metals belonging to groups 4 to 8 in the above-mentioned formula are oxides of metals belonging to groups 4 to 8 in the above-mentioned formula. Vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide Rhenium oxide, manganese oxide, and rhenium oxide are preferred because of their high electron-accepting properties. In particular, molybdenum oxide is preferred because it is stable in the air, has low hygroscopicity, and is easy to handle. It is a substance.

[0053] As a substance having a high hole transporting property that can be used for the above composite material, an aromatic amine compound compounds, carbazole derivatives, aromatic hydrocarbons, polymers including oligomers and dendrimers As long as the material has a higher hole transporting capacity than the electron transporting capacity, It is possible to use -6 cm 2 / Vs or more. In the following, specific examples of organic compounds that can be used in the composite material are described. Enumerate.

[0054] The aromatic amine compound that can be used in the above composite material is N,N'-di(p- tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4 ,4'-Bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl DPAB, N,N'-bis[4-[bis(3-methylphenyl)amino] phenyl]-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation Name: DNTPD), 1,3,5-tris[N-(4-diphenylaminophenyl)-N- phenylamino]benzene (abbreviation: DPA3B), 4-phenyl-4'-(9-phenyl fluoren-9-yl)triphenylamine (abbreviation: BPAFLP) and the like. Cut.

[0055] Specific examples of carbazole derivatives that can be used in the above composite material include 3-[ N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazol Carbazole (abbreviation: PCzPCA1), 3,6-bis[N-(9-phenylcarbazole -3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA 2) 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amine 1,2-diphenylcarbazole (abbreviation: PCzPCN1), etc. Other examples of carbazole derivatives include 4,4'-di(N-carbazolyl)biphenyl. (abbreviation: CBP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (Abbreviation: TCPB), 9-[4-(10-phenyl-9-anthryl)phenyl]-9H -Carbazole (abbreviation: CzPA), 9-phenyl-3-[4-(10-phenyl-9- anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), 1,4-bis[4 -(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene, etc. It is possible.

[0056] Examples of aromatic hydrocarbons that can be used in the composite material include 2-tert-butyl ether, t-Butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 2 -tert-butyl-9,10-di(1-naphthyl)anthracene, 9,10-bis(3 ,5-diphenylphenyl)anthracene (abbreviation: DPPA), 2-tert-butyl- 9,10-Bis(4-phenylphenyl)anthracene (abbreviation: t-BuDBA), 9, 10-Di(2-naphthyl)anthracene (abbreviation: DNA), 9,10-diphenylanthracene Helical anthracene (abbreviation: DPAnth), 2-tert-butylanthracene (abbreviation: t-BuA nth), 9,10-bis(4-methyl-1-naphthyl)anthracene (abbreviation: DMNA ), 2-tert-butyl-9,10-bis[2-(1-naphthyl)phenyl]anthracene 9,10-bis[2-(1-naphthyl)phenyl]anthracene, 2,3,6,7 -Tetramethyl-9,10-di(1-naphthyl)anthracene, 2,3,6,7-tetramethyl- Methyl-9,10-di(2-naphthyl)anthracene, 9,9'-bianthryl, 10, 10'-diphenyl-9,9'-bianthryl, 10,10'-bis(2-phenylphenyl) 10,10'-bis[(2,3,4,5,6-pentanyl) Phenyl)phenyl]-9,9'-bianthryl, anthracene, tetracene, rubrene , perylene, and 2,5,8,11-tetra(tert-butyl)perylene. In addition, pentacene, coronene, etc. can also be used. - 6 cm 2 / Vs or more, and uses aromatic hydrocarbons with carbon numbers of 14 to 42. It is more preferable to do so.

[0057] The aromatic hydrocarbon that can be used in the composite material may have a vinyl skeleton. Examples of aromatic hydrocarbons having a vinyl group include 4,4'-bis(2,2-diphenyl ether). 9,10-bis[4-(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi) phenylvinyl)phenyl]anthracene (abbreviation: DPVPA), and the like.

[0058] In addition, poly(N-vinylcarbazole) (abbreviation: PVK) and poly(4-vinyltriphenylphosphine) nylamine) (abbreviation: PVTPA), poly[N-(4-{N'-[4-(4-diphenyl Amino)phenyl]phenyl-N'-phenylamino}phenyl)methacrylamide]( abbreviation: PTPDMA), poly[N,N'-bis(4-butylphenyl)-N,N'-bis Polymer compounds such as Poly(phenyl)benzidine (abbreviation: Poly-TPD) can also be used. can.

[0059] A composite material consisting of a material with high hole transport properties and a material that exhibits acceptor properties for the material The thickness adjusting layer made of the material layer has excellent hole transport and hole injection properties, and is therefore provided in contact with the anode. It is preferable that

[0060] Next, a material having a high electron transporting property and a material having a donor property to the material having a high electron transporting property is used. Explain composite materials.

[0061] Substances that exhibit donor properties include alkali metals, alkaline earth metals, and their compounds. It can be used.

[0062] An example of a material with high electron transport properties is tris(8-quinolinolato)aluminum (A lq), tris(4-methyl-8-quinolinolato)aluminum (abbreviation: Almq3), Bis(10-hydroxybenzo[h]quinolinato)beryllium (BeBq2), Bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum (abbreviation: These include metal complexes having a quinoline or benzoquinoline skeleton, such as BAlq. In addition, bis[2-(2-hydroxyphenyl)benzoxazolato]zinc (abbreviation: Z n(BOX)2), bis[2-(2-hydroxyphenyl)benzothiazolato]zinc (abbreviation Metal complexes with oxazole and thiazole ligands, such as Zn(BTZ)2) In addition to metal complexes, 2-(4-biphenylyl)-5- (4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD) , 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazo [2-yl]benzene (abbreviation: OXD-7), 3-(4-biphenylyl)-4-phenyl TAZ ), bathophenanthroline (abbreviated as BPhen), bathocuproine (abbreviated as BCP) The substances mentioned here are mainly 10 -6 cm 2 / Vs or more In addition, as long as the material has a higher electron transporting property than the hole transporting property, The following substances may be used.

[0063] Next, a material having a high electron transporting property and a material having a donor property to the material having a high electron transporting property is used. The thickness adjusting layer made of the composite material layer has excellent electron transport and injection properties, so it is It is preferable to provide such a function.

[0064] The light emitting device in this embodiment is an extremely thin film with an optical distance of the resonant structure exceeding 650 nm. The optical distance of the resonant structure is the distance between the reflective electrode and the light emitting element. The light emitted from the light-emitting layer is reflected by the reflective electrode and the By repeatedly reflecting light in the semi-transparent, semi-reflective electrode, the light is adjusted to the optical distance. The light of the wavelength that corresponds to the wavelength is strengthened or weakened. This is where such a resonant structure is formed. In this case, the condition for amplification by resonance is that the optical distance of the resonant structure is an integer multiple of half the wavelength. (mλ / 2, where λ is the wavelength and m is an integer). Considering that the refractive index of organic materials is 1.7, this is possible in the element (approximately 200 nm). It turns out that the limit is to match one λ / 2 wavelength in any color in the visual range. However, in the light emitting device of this embodiment in which the optical distance of the resonant structure exceeds 650 nm, In this way, a resonant structure with different magnifications can be formed at multiple wavelengths. The optical distance of 650 nm is the wavelength of 3λ / 2 of the wavelength band that is visually perceived as blue and the wavelength of 3λ / 2 of the wavelength band that is visually perceived as red. In a light-emitting device with an optical film thickness of 650 nm, the wavelengths of blue and red are The resonant structure can be formed at multiple wavelengths. Green light has a high visibility. Therefore, a light-emitting device that forms a resonant structure at blue and red wavelengths exhibits well-balanced white light emission. However, if the thickness of the EL layer is too thick, the manufacturing time will be increased. becomes too long, so the upper limit is preferably about 1500 nm.

[0065] The optical distance of the resonant structure of the light-emitting element is 3λ wavelength for blue, 5λ / 2 wavelength for green, and 2λ wavelength for red. It is more preferable that the wavelength is 1290 nm to 1400 nm, which corresponds to the wavelength of the optical fiber. The light-emitting device having a resonance structure with a distance has a resonance structure corresponding to all three colors of blue, green, and red. This makes it easy to obtain white light emission of a desired color. In addition, a light-emitting element with higher luminous efficiency can be obtained.

[0066] In the above, we have only discussed the three colors blue, green, and red, but there are also resonant structures for other wavelengths. The spectrum of the light-emitting element has intensity over a range of several tens of nanometers before and after the peak. In the light emitting device of the present embodiment, the wavelength is not the peak wavelength but the intermediate color. By forming a resonant structure at multiple wavelengths, a broad spectrum like blackbody radiation can be obtained. This helps to achieve this and is a preferable configuration for lighting applications where color rendering is also important.

[0067] In addition, since the light emitting element in this embodiment has a very large optical distance, it is difficult to determine the light emitting position. Even in this case, it is possible to obtain the resonance effect. It is difficult to define the exact amount of time required for the job because it varies depending on factors such as career balance. In the light-emitting device described in the embodiment, it is possible to obtain an amplification effect without taking this into consideration. It is.

[0068] The present embodiment is a light emitting device having a microcavity structure that can accommodate multiple wavelengths. A photonic device can be provided.

[0069] In addition, it is possible to produce multiple wavelengths with a single element structure without producing multiple elements with different resonant structures. Since a resonant structure can be formed for the light, it is possible to easily obtain a lighting device with excellent color temperature. .

[0070] In the case of FIG. 1B, the reflective surface and the semi-reflective surface that constitute the resonant structure 106 are the first reflective electrodes. The upper surface of the first electrode 101 corresponds to the upper surface of the second electrode 102 which is a semi-transparent semi-reflective electrode. The reflection at the top surface of the second electrode 102 is caused by the second electrode 102 and the material on the second electrode 102. In this case, the resonant structure 106 is a first The EL layer 103 is formed between the upper surface of the electrode 101 and the upper surface of the second electrode 102. The second electrode 102 contributes to the optical path length.

[0071] In this case, the second electrode 102 is made of a conductive metal oxide having light-transmitting properties (indium oxide ( In2O3), tin oxide (SnO2), zinc oxide (ZnO), ITO, indium oxide zinc oxide (In2O3-ZnO), or these metal oxide materials containing silicon oxide The conductive layer can be formed of a transparent conductive metal oxide such as a transparent conductive metal oxide having a thickness of 100 nm or more.

[0072] Note that the second electrode 102 may be formed by stacking a metal and a light-transmitting metal oxide. do.

[0073] In the configuration of FIG. 1B, a refractive index layer is formed on the second electrode 102, which is a semi-transmissive semi-reflective electrode. A material having a light transmittance of 1 to 2.3 may be laminated. In this case, The material may or may not be conductive. For example, the present invention relates to an organic compound having the above-mentioned carrier transport property and an access to the organic compound. Substances used as materials for the EL layer, such as composite materials with substances that exhibit anti-reflection or donor properties, An organic insulating film or an inorganic insulating film having such a structure can be used. It is possible to increase the light-emitting element's resonant structure that can accommodate many wavelengths. It is possible.

[0074] (Embodiment 2) In this embodiment mode, materials and manufacturing methods of the EL layer and the electrodes described in Embodiment Mode 1 will be described. Let me explain in detail.

[0075] Specific examples of materials that constitute the reflective electrode include aluminum (Al), gold (Au), Platinum (Pt), Nickel (Ni), Tungsten (W), Chromium (Cr), Molybdenum ( Mo), iron (Fe), cobalt (Co), copper (Cu), or palladium (Pd), etc. Metallic materials, compounds and alloys thereof, etc. can be used.

[0076] When the semi-transmitting / semi-reflective electrode is made of metal, it is preferable to use a thin metal film (preferably 20 nm or less, more preferably The thin metal film can be formed to a thickness of preferably 10 nm or less. The use of a single layer or a multilayer of alloys containing these metal materials. is possible.

[0077] When the semi-transmitting / semi-reflective electrode is made of a conductive metal oxide having light transmitting properties, the insulating film is In2O3, tin oxide (SnO2), zinc oxide (ZnO), ITO, indium oxide In2O3-ZnO, or these metal oxide materials with silicon oxide It is possible to use one containing kon.

[0078] In addition, the light-transmitting material having a refractive index of 1 to 2.3 formed on the semi-transmitting semi-reflective electrode is conductive. The material may or may not have electrical conductivity. For example, a conductive metal oxide having a light transmitting property, a carrier transporting property described in the first embodiment, A composite material of an organic compound and a substance that exhibits acceptor or donor properties for the organic compound. The materials used for the EL layer, organic insulating films and inorganic insulating films with light-transmitting properties, etc. There can be.

[0079] Reflective electrode and semi-transparent semi-reflective electrode (or a conductive metal oxide having light-transmitting properties) The electrode (electrode) can be either an anode or a cathode, but the work function of these materials is determined by the anode or cathode. If the function required for the cathode is not met, carrier injection occurs at the interface between the EL layer and the electrode. By forming a layer, a metal with a low (or high) work function is used as the anode (or cathode). As a carrier injection layer on the anode side, a highly porous material with high hole transport properties can be used. A composite material consisting of a thin organic compound and an acceptor material, which acts as a carrier injection layer on the cathode side. The composite material consisting of an organic compound with high electron transport properties and a donor substance is used to inject carriers. The carrier injection layer made of these composite materials can be suitably used as a layer having a thickness that can be easily adjusted. It can also serve as a joint layer.

[0080] In addition, when a thickness adjusting layer is provided in contact with the anode, the thickness adjusting layer is made of a conductive metal oxide. Conductive metal oxides have a high work function and can form holograms on organic compounds. It is easy to inject ions into the film, and can be suitably used as a film thickness adjusting layer on the anode side.

[0081] The anode 702 and the cathode 704 may be formed by sputtering, electrolytic deposition, or the like, depending on the materials used. Vacuum deposition method, ion plating method, MBE (molecular beam epit axy) method, CVD method (MOCVD (metal organic CVD) method and ALD (atomic layer deposition) method, sol-gel method, spin coating method, It can be prepared by known methods such as the dipping method, dipping method, spray method, coating method, and printing method. can.

[0082] The laminated structure of the EL layer 103 is not particularly limited. a hole transport layer containing a substance with high hole transport properties; a hole injection layer containing a material with high hole injection properties; The structure is constructed by appropriately combining each functional layer, such as a bipolar layer containing a material with high transport properties. These functional layers are not essential except for the light-emitting layer, and no other functional layers than those described above may be used. Such a laminated structure may be called a light-emitting unit.

[0083] In the light emitting device of the present embodiment, with respect to the optical distance L between the reflective electrode and the semi-reflective surface, Emission that emits light at at least two wavelengths λ satisfying L=nλ / 2 (n is an integer of 2 or more). The layer is

[0084] In this embodiment, the EL layer 103 includes, from the anode 702 side, a hole injection layer 711, a hole transport layer 7 12. Regarding the structure having a laminated structure of a light-emitting layer 713, an electron transport layer 714, and an electron injection layer 715 The structure and materials of each layer will be specifically described below.

[0085] The hole injection layer 711 is provided in contact with the anode 702 and is a layer containing a material with high hole injection properties. There are molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, Manganese oxide, etc. can be used. In addition, phthalocyanine (abbreviation: H2Pc) Phthalocyanine compounds such as copper phthalocyanine (CuPC), DPAB, DNTPD, etc. Aromatic amine compounds, or poly(ethylenedioxythiophene) / poly(styrenes) The hole injection layer 711 may also be formed from a polymer such as PEDOT / PSS. It is possible.

[0086] In addition, the hole-injection layer 711 may be made of a material having a high hole-transporting property. A composite material containing a substance that exhibits acceptor properties for the fluorine atom can also be used. By forming the composite material in contact with the anode, the material for forming the anode can be selected regardless of the work function. In other words, the material that constitutes the anode is not only a material with a large work function, but also a material that has a specific function. A material with a small thermal expansion coefficient can also be used. Since the material is the same as the composite material, the repeated description will be omitted. When 1 is formed from the above composite material, the hole injection layer 711 also functions as a film thickness adjusting layer.

[0087] The hole-transporting layer 712 is a layer containing a substance having a high hole-transporting property. Examples of such compounds include 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl. N,N'-bis(3-methylphenyl)-N,N'-diphenyl -[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4',4'' -Tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA), 4, 4',4''-Tris[N-(3-methylphenyl)-N-phenylamino]triphenyl 4,4'-bis[N-(spiro-9,9'-bifluorophenyl)amine (abbreviation: MTDATA), [2-phenyl-2-yl]-N-phenylamino]biphenyl (abbreviation: BSPB), BPAFLP The aromatic amine compounds mentioned here are mainly 10 -6 cm 2 The hole mobility of the composite material is 1 / Vs or more. The organic compounds given as the substances with high transport properties can also be used for the hole-transporting layer 712. However, other materials may be used as long as they have a higher hole transporting property than an electron transporting property. The layer containing a substance having a high hole transporting property may be a single layer or a layer having two layers of the above substance. It may be a laminate of more than one layer.

[0088] In addition, a polymer compound such as PVK or PVTPA may be used as the hole transport layer 712. can.

[0089] The light-emitting layer 713 is a layer containing a light-emitting substance. Even if the emitting layer is a single film, the emitting material is dispersed in the host material, so-called host-guest The light emitting layer may be of either type or a transparent type.

[0090] There is no limitation on the luminescent center material to be used, and any known fluorescent or phosphorescent material may be used. As a fluorescent material, for example, N,N'-bis[4-(9H-carbazole -9-yl)phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviation :YGA2S), 4-(9H-carbazol-9-yl)-4'-(10-phenyl-9 -anthryl)triphenylamine (abbreviation: YGAPA), etc., and m or more of 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl-2- Anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-diphenyl-N- [4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole-3-amine PCAPA, Perylene, 2,5,8,11-Tetra-tert-butyl-Perylene TBP, 4-(10-phenyl-9-anthryl)-4'-(9-phenyl N,N-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA) N''-(2-tert-butylanthracene-9,10-diyldi-4,1-phenyl N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: DP ABPA), N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl )phenyl]-9H-carbazol-3-amine (abbreviation: 2PCAPPA), N-[4- (9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl -1,4-Phenylenediamine (abbreviation: 2DPAPPA), N,N,N',N',N'' ,N'',N''',N'''-Octaphenyldibenzo[g,p]chrysene-2,7, 10,15-Tetraamine (abbreviation: DBC1), Coumarin 30, N-(9,10-diphenyl N,9-diphenyl-9H-carbazol-3-amine (abbreviation : 2PCAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-a Triphenyl-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCAB PhA), N-(9,10-diphenyl-2-anthryl)-N,N',N'-triphenyl Nyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-bis(1 ,1'-biphenyl-2-yl)-2-anthryl]-N,N',N'-triphenyl- 1,4-Phenylenediamine (abbreviation: 2DPABPhA), 9,10-bis(1,1'- Biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N -Phenylanthracene-2-amine (abbreviation: 2YGABPhA), N,N,9-triphenyl Phenylanthracene-9-amine (abbreviation: DPhAPhA), Coumarin 545T, N,N '-Diphenylquinacridone (abbreviation: DPQd), rubrene, 5,12-bis(1,1' -biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT), 2-( 2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyran -4-ylidene)propanedinitrile (abbreviation: DCM1), 2-{2-methyl-6-[2 -(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl ) ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM2), N,N,N',N'-Tetrakis(4-methylphenyl)tetracene-5,11-diamine p-mPhTD, 7,14-diphenyl-N,N,N',N'-tetrakis(III) (4-Methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviation: p-mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7- Tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizine -9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: D CJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl -2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl) ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB), 2-(2,6-bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyra 2-{2,6-bis[ 2-(8-Methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro- 1H,5H-Benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-yl bis(diphenyl)propanedinitrile (abbreviation: BisDCJTM). The material is, for example, bis[2-(4',6'-difluorophenyl)pyridinato-N ,C 2’ ]Iridium(III) tetrakis(1-pyrazolyl)borate (abbreviation: FIr 6), and bis[2-(4',6' -Difluorophenyl)pyridinato-N,C 2’ ]Iridium(III) picolinate( Abbreviation: FIrpic), bis[2-(3',5'-bistrifluoromethylphenyl)pic Lysinato-N,C 2’ ]Iridium(III) picolinate (abbreviation: Ir(CF3ppy )2(pic)), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]Iridium(III) acetylacetonate (abbreviation: FIracac), emission wavelength is Tris(2-phenylpyridinato)iridium(III) above 500 nm (green emission) (abbreviation: Ir(ppy)3), bis(2-phenylpyridinato)iridium(III) Cetylacetonate (abbreviation: Ir(ppy)2(acac)), Tris(acetylacetonate) Tb(acac)3(Ph en)), bis(benzo[h]quinolinato)iridium(III) acetylacetonate ( Abbreviation: Ir(bzq)2(acac)), bis(2,4-diphenyl-1,3-oxazo Rato-N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: Ir(dpo)2 (acac)), bis[2-(4'-perfluorophenylphenyl)pyridinato]yl Ir(p-PF-ph)2(acac) , bis(2-phenylbenzothiazolato-N,C 2’ ) Iridium(III) acetylated Setonato (abbreviation: Ir(bt)2(acac)), bis[2-(2'-benzo[4,5- α]Thienyl)pyridinato-N,C 3’ ]Iridium(III) acetylacetonate (abbreviation Name: Ir(btp)2(acac)), bis(1-phenylisoquinolinato-N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: Ir(piq)2(acac)), (Acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato] Iridium(III) (abbreviation: Ir(Fdpq)2(acac)), (acetylacetonate Bis(2,3,5-triphenylpyrazinate)iridium(III) (abbreviation: Ir( tppr)2(acac)), 2,3,7,8,12,13,17,18-octaethyl -21H,23H-Porphyrin platinum(II) (abbreviation: PtOEP), tris(1,3- Diphenyl-1,3-propanedionato)(monophenanthroline)europium(II) I) (abbreviation: Eu(DBM)3(Phen)), tris[1-(2-thenoyl)-3,3 ,3-Trifluoroacetonato](monophenanthroline)europium(III)(abbreviation These and other known materials include Eu(TTA)3(Phen). The materials may be selected taking into consideration the emission color of each EL element.

[0091] When using a host material, for example, Alq, Almq3, BeBq2, BAlq, Bis (8-quinolinolato)zinc(II)(abbreviation: Znq), bis[2-(2-benzoxazolidinediamine] aryl)phenolato]zinc(II) (abbreviation: ZnPBO), bis[2-(2-benzothiazo Metal complexes such as [aryl)phenolato]zinc(II) (abbreviation: ZnBTZ), PBD, OXD -7, TAZ, 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl 1H-benzimidazole) (abbreviation: TPBI), BPhen, BCP, 9-[4 -(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-cal Heterocyclic compounds such as bazoline (abbreviation: CO11), NPB (or α-NPD), and TPD In addition, aromatic amine compounds such as anthracene derivatives, phenanthracene derivatives, etc. Thiolane derivatives, pyrene derivatives, chrysene derivatives, dibenzo[g,p]chrysene derivatives, etc. Condensed polycyclic aromatic compounds such as DPAnth, N,N-diphenyl- 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole-3- Amine (abbreviation: CzA1PA), 4-(10-phenyl-9-anthryl)triphenyl Amine (abbreviation: DPhPA), YGAPA, PCAPA, N,9-diphenyl-N-{4 -[4-(10-phenyl-9-anthryl)phenyl]phenyl}-9H-carbazol PCAPBA, 2PCAPA, DBC1, CzPA, 3,6- Diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carba DPCzPA, DPPA, DNA, t-BuDNA, 9,9'-bian Tolyl (abbreviation: BANT), 9,9'-(stilbene-3,3'-diyl) diphenanthate DPNS, 9,9'-(stilbene-4,4'-diyl)diphenanthrene DPNS2, 3,3',3''-(benzene-1,3,5-triyl)triphenylphosphine Pyrene (abbreviation: TPB3) and the like. Among these and other known substances, The energy gap of each dispersed luminescent material (triplet energy in the case of phosphorescence) The material has a larger energy gap (triplet energy) than the layer A substance that exhibits transport properties that match the desired transport properties may be selected.

[0092] The light-emitting layer may be a single layer or a stack of light-emitting layers containing light-emitting substances that emit different colors of light. In the case where the light-emitting layer is a single layer, the light-emitting layer may contain multiple light-emitting materials that emit light of different wavelengths. In addition, the light-emitting layer may have a structure in which the same light-emitting center material is contained in different host materials. It may be a layer.

[0093] The electron transport layer 714 is a layer containing a substance having a high electron transporting property. Examples of the highly electron-transporting substances include those shown above.

[0094] The electron transport layer 714 may be a single layer or may be a laminate of two or more layers of the above-mentioned material. It may also be layered.

[0095] In addition, a layer for controlling the movement of electrons may be provided between the electron transport layer 714 and the light emitting layer 713. This is done by adding a small amount of a substance with high electron trapping properties to a material with high electron transport properties as described above. This layer is added to the semiconductor layer, and it is possible to adjust the carrier balance by suppressing the movement of electrons. Such a configuration is possible because electrons pass through the light-emitting layer 713. This is highly effective in preventing problems that may occur (such as a reduction in element life).

[0096] The electron injection layer 715 may be formed of lithium fluoride (LiF), cesium fluoride (CsF), Alkali metals or alkaline earth metals such as calcium fluoride (CaF2) or Alternatively, the compound having the above electron transporting property may be included in a layer made of a substance having an electron transporting property. Substances that exhibit electron donating properties to substances with electron transport properties (typically alkali metals or A layer containing potassium earth metals or their compounds (materials having donor levels), e.g. A layer containing magnesium (Mg) in Alq is used as the electron injection layer 715. Note that the structure in which a material having a donor level is used as the electron injection layer 715 is a negative This is a more preferable configuration since electron injection from the electrode 704 is performed efficiently.

[0097] The above-mentioned EL layer 103 is formed between the anode 702 and the cathode 704 as shown in FIG. 2(B). A structure in which a plurality of units are stacked may be used. In this case, the stacked first light-emitting units A charge generating layer 803 may be provided between the unit 800 and the second light emitting unit 801. The charge generation layer 803 is preferably made of the above-mentioned organic compound having high hole transport properties and the organic compound The charge generating layer can be formed of a composite material composed of a material exhibiting acceptor properties. 803 may be a laminated structure of a layer of a composite material and a layer of another material. The layer made of the material may be a layer containing a donor substance and a substance having high electron transport properties, or a layer containing a light-transmitting A layer made of a conductive metal oxide having such a structure can be used. The EL element that uses this technology has a dramatically improved current efficiency, so it has both high power efficiency and a long life. It is easy to make an EL element that has one light-emitting unit that emits phosphorescence and the other that emits fluorescent light. It is also easy to obtain light emission.

[0098] In FIG. 2B, two light-emitting units (a first light-emitting unit 800 and a second light-emitting unit 810) are shown. Although the configuration in which the light emitting units 801) are stacked has been illustrated, a configuration in which three or more light emitting units are stacked In this case, a charge generating layer is provided between each light emitting unit. It is preferable that the charge generating layer 803 also functions as a film thickness adjusting layer.

[0099] Each light-emitting unit has a structure similar to that of the EL layer 103 in FIG. The detailed explanation of the layers included in each unit has been given above, so this explanation will not be repeated here. The explanation is omitted here, see the explanation of the EL layer 103 in FIG.

[0100] In particular, the structure of FIG. 2B is suitable for the light-emitting element described in Embodiment 1 which requires a large film thickness. In addition, it is easy to obtain light of different colors simultaneously. Therefore, it is particularly effective for lighting applications. This makes it possible to provide a light-emitting device with an excellent color temperature for lighting applications. can be obtained.

[0101] (Embodiment 3) In this embodiment mode, an example in which the light-emitting element described in Embodiment 1 is used as a lighting device is shown in FIG. The description will be given with reference to FIG. 3(B) is a top view of the lighting device, and FIG. 3(A) is a schematic diagram of the lighting device in FIG. 3(B). FIG.

[0102] The lighting device in this embodiment includes a first electrode 40 on a supporting substrate 400 serving as a support. The first electrode 401 corresponds to the first electrode 101 in the first embodiment. When the lighting device is a bottom emission type, the material of the support substrate 400 may be glass, quartz, or a ceramic. In the case of a top-emitting type, the support substrate 400 is made of a transparent material such as a plastic. It does not have to be optically transparent. In addition to the above materials, metals, semiconductors, ceramics, and colored organic materials are also available. Materials such as resin can be used. When a conductive substrate is used, its surface is oxidized. Alternatively, it is preferable to provide the surface with insulating properties by forming an insulating film on the surface.

[0103] When an organic resin is used as the support substrate 400, the organic resin may be, for example, polyethylene. Polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) Fatty acids, polyacrylonitrile resins, polyimide resins, polymethyl methacrylate resins, poly Carbonate (PC) resin, polyethersulfone (PES) resin, polyamide resin, Polycycloolefin resin, polystyrene resin, polyamide-imide resin, or polychlorinated Vinyl resin can be used. In addition, a substrate made of glass fiber impregnated with organic resin, It is also possible to use a substrate in which an inorganic filler is mixed with an organic resin.

[0104] In particular, in the case of a so-called top-emitting type light-emitting device in which light is extracted from the sealing substrate 407 side, It is preferable to use a substrate with high thermal conductivity such as a metal substrate for the substrate 400. In the case of a large light-emitting device using this method, heat generation from the EL element can be a problem. Using a substrate with high thermal conductivity like this will improve heat dissipation. For example, in addition to stainless steel substrates, If aluminum or duralumin is used, it will be lightweight and have high heat dissipation properties. In addition, laminates of aluminum and aluminum oxide, duralumin and aluminum oxide By using laminates of duralumin and magnesium oxide, the surface of the substrate can be made insulating. This is preferable because

[0105] An EL layer 403 is formed on the first electrode 401. The EL layer 403 is the same as that of the first embodiment. This corresponds to the configuration of the EL layer 103 in the second embodiment. Please refer to the description. The EL layer 403 is formed to be slightly larger than the first electrode 401 when viewed in a plan view. This is preferable because it also serves as an insulating layer to prevent a short circuit between the first electrode 401 and the second electrode 404. This is a desirable configuration.

[0106] Next, a second electrode 404 is formed to cover the EL layer 403. This corresponds to the second electrode 102 in the first embodiment and has the same configuration. The second electrode 404 is connected to a pad 412 to supply a voltage. do.

[0107] As described above, a light-emitting element having the first electrode 401, the EL layer 403, and the second electrode 404 is The lighting device shown in the embodiment has a resonant structure for a plurality of wavelengths. Since the light emitting element has the above structure, the lighting device in this embodiment has excellent color temperature. In addition, the lighting device can consume less power. It is possible to create a resonant structure for multiple wavelengths with a single element structure without creating multiple elements with different structures. Since the above-mentioned structure can be formed, it is possible to easily obtain a lighting device with excellent color temperature.

[0108] The light emitting element having the above structure is fixed to a sealing substrate 407 using sealing materials 405 and 406. The lighting device is completed by attaching and sealing the sealing materials 405 and 406. Also, a desiccant can be mixed into the inner sealant 406. This allows the sealing substrate 407 to adsorb moisture, leading to improved reliability. A space 408 surrounded by a support substrate 400 on which optical elements are formed and sealing materials 405 and 406 is A reduced pressure atmosphere is acceptable, but other atmospheres such as air that does not contain moisture or oxygen, dry nitrogen, etc. It may be filled with a gas, a liquid such as a sealing material, or a solid.

[0109] In addition, a part of the pad 412 and the first electrode 401 extends outside the sealing materials 405 and 406. By providing a 1 / 4" connector on the 1 / 4" input, it can be used as an external input terminal. An IC chip 420 incorporating the above may be provided.

[0110] It is preferable to use epoxy resin or glass frit for the sealing material 405. In addition, it is desirable that these materials are as impermeable to moisture and oxygen as possible. The material used for the sealing substrate 407 may be a glass substrate, a quartz substrate, or FRP (Fibre Reinforced Plastics). Glass-Reinforced Plastics), PVF (Polyvinyl fluoride ), a plastic substrate made of polyester or acrylic resin, etc. can be used. When glass frit is used as the sealing material, the support substrate 400 and the The sealing substrate 407 is preferably a glass substrate.

[0111] In addition, the present embodiment using the light-emitting device having the microcavity structure described in the first embodiment In the lighting device in the above embodiment, the emitted light has directivity, so that the surface of the lighting device and the sealing substrate A structure for diffusing light may be provided on a surface that intersects with the light emission, such as the back surface of the plate 407. Examples of the structure include a hemispherical lens or a microlens array with a concave-convex structure. A light diffusion film or the like may be attached, or the uneven shape may be directly formed on the support substrate 400 or the sealing substrate 400. It may be formed in 07.

[0112] As described above, the lighting device according to the present embodiment uses the light-emitting element according to the first embodiment as the light-emitting element. Since the LEDs are used, it is possible to provide a lighting device with a color temperature suitable for lighting purposes. In addition, the lighting device can consume less power and is inexpensive. can be done.

[0113] (Embodiment 4) In this embodiment, a lighting device using a light-emitting device formed according to one embodiment of the present invention will be described. This will be explained with reference to FIG. 4 and FIG.

[0114] FIG. 4 shows a lighting device (tabletop lighting device), which includes a lighting unit 7501, a shade 7502, and a variable arm 7503. 503, a support 7504, a stand 7505, and a power switch 7506. The light-emitting device according to one embodiment of the present invention is used for the lighting portion 7501. In addition to the tabletop lighting device shown in Figure 4, the lighting device may also be a ceiling-mounted lighting device (ceiling-mounted This also includes standard lighting devices (fixed lighting devices) or wall-mounted lighting devices (wall-mounted lighting devices).

[0115] Note that a lighting device formed by applying one embodiment of the present invention has high reliability and manufacturing yield. Since it is a lighting device, by using it for the lighting part 7501 of the lighting device, it is highly reliable and price competitive. In addition, a highly competitive lighting device can be provided. The lighting device can be a lighting device with low power consumption.

[0116] FIG. 5 illustrates a tabletop lighting device 3000 and a light-emitting device formed by applying one embodiment of the present invention. The light-emitting device according to one embodiment of the present invention is used as an indoor lighting device. As a lighting device with high light output, it is suitable for lighting large areas, as shown in the ceiling-mounted lighting device 3001. In addition, the device can be used as a wall-mounted lighting device 3002. In addition, a lighting device formed according to one embodiment of the present invention can be used. It can be a small lighting device. EXAMPLES

[0117] In this example, the light-emitting element described in Embodiment 1, which is one embodiment of the present invention, will be described. The molecular structures of the organic compounds used in this example are shown below.

[0118] [ka]

[0119] <Fabrication of light-emitting element> First, aluminum-titanium alloy (Al-Ti) and titanium (Ti) were used as the first electrode. The reflective electrode layer was formed by successively depositing the aluminum film and the aluminum alloy film by sputtering. -The titanium alloy was deposited to a thickness of 200 nm and the titanium to a thickness of 6 nm. The substrate was heated at 300°C for 1 hour to form a layer containing titanium oxide. A film of indium tin oxide (ITSO) was formed to a thickness of 70 nm to serve as a film thickness adjustment layer. The surface of the layer is covered with a polyimide film so that the surface is exposed in a size of 2 mm square. The area was 2 mm × 2 mm. As a pretreatment for forming a light-emitting element on this substrate, The plate surface was washed with water, baked at 200°C for 1 hour, and then subjected to UV ozone treatment for 370 seconds. Then, 10 -4 The substrate is placed in a vacuum deposition apparatus whose inside has been reduced in pressure to about Pa, and vacuum deposition is performed. After vacuum baking at 170°C for 30 minutes in the heating chamber of the device, the substrate was left exposed for about 30 minutes. It's cold.

[0120] Next, the substrate was placed in a vacuum deposition apparatus so that the surface on which the ITSO was formed faced downward. The specimen was then fixed in a holder.

[0121] 10 minutes in the vacuum chamber -4 After reducing the pressure to 10 Pa, PCzPA represented by the above structural formula (ii) was Molybdenum oxide (VI) was mixed with PCzPA in a ratio of 1:0.5 (by weight) The deposition rate is adjusted so that the ratio of the deposition rate to the thickness of the hole An injection layer was formed. The film thickness was 30 nm. Co-evaporation is the process of depositing multiple different materials together. This is a deposition method in which different evaporation sources are evaporated simultaneously.

[0122] Subsequently, a first hole transport layer was formed by depositing PCzPA to a thickness of 20 nm.

[0123] Further, on the first hole transport layer, CzPA represented by the above structural formula (i) and N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9 -phenyl-9H-fluoren-9-yl)phenyl]-pyrene-1,6-diamine (abbreviation Name: 1,6mMemFLPAPrn), CzPA: 1,6mMemFLPAPrn=1 The deposition rate was adjusted so that the weight ratio was 0.05, and 30 nm of the film was deposited. A first light-emitting layer was formed.

[0124] Next, a first electron transport layer was formed by depositing 5 nm of CzPA on the first light-emitting layer. Then, BPhen represented by the above structural formula (iv) was vapor-deposited to a thickness of 15 nm to form a second An electron transport layer was formed.

[0125] Furthermore, calcium was deposited on the second electron transport layer to a thickness of 1 nm as an electron injection buffer layer. Then, CuPc represented by the above structural formula (v) is deposited as an electron relay layer. The electron relay layer was then coated with PCzPA and molybdenum oxide to a thickness of 100 nm. (VI) was co-evaporated in a ratio of PCzPA:molybdenum oxide (VI) = 1:0.5, and then electrochemically A charge generating layer was formed. The thickness of the charge generating layer was 30 nm. The charge generating layer also serves as a film thickness adjusting layer.

[0126] Next, BPAFLP represented by the above structural formula (vi) was evaporated to a thickness of 20 nm, and the second hole transport layer was formed. A transfer layer was formed.

[0127] Furthermore, 2-[3-(dibenzothiophene-4-yl) )phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II) and 4-phenyl-4'-(9-phenyl-9H-carbazone) represented by the following structural formula (viii): (3-yl)triphenylamine (abbreviation: PCBA1BP) and the above structural formula (ix) (Acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridide Ir(mppm)2(acac) and 2mDBTPDBq- II:PCBA1BP:Ir(mppm)2(acac)=0.8:0.2:0.06( The second light-emitting layer was formed by co-evaporation so that the thickness of the layer was 20 nm. did.

[0128] Next, 2mDBTPDBq-II and (dipivaloylmetha) represented by the above structural formula (x) were Nato)bis(2,3,5-triphenylpyrazinate)iridium(III) (abbreviation: Ir (tppr)2(dpm)) to 2mDBTPDBq-II:Ir(tppr)2(dpm The third light-emitting layer was formed by co-evaporation so that the ratio of the layers was 2:0.02 (weight ratio). It was set to 0 nm.

[0129] After this, 2mDBTPDBq-II was deposited to a thickness of 15 nm, and the third electron transport layer was then deposited. A 15 nm thick film of phenan was then formed to form a fourth electron transport layer.

[0130] Then, lithium fluoride is evaporated onto the fourth electron transport layer to a thickness of 1 nm, and electron injection is performed. A layer was formed, and a film containing silver and magnesium was formed on the layer. Then, a 10 nm thick film of ITSO is formed to form a second electrode. Thus, the light-emitting element 1 was fabricated.

[0131] The element structure of the light-emitting element 1 is shown in Table 1.

[0132] [Table 1]

[0133] <Operation characteristics of light-emitting element 1> The light-emitting device 1 obtained in the above manner is placed in a glove box with a nitrogen atmosphere. After sealing to prevent exposure to the atmosphere, the operating characteristics of the light-emitting device were evaluated. The measurements were carried out at room temperature (atmosphere maintained at 25°C).

[0134] Figure 6 shows the luminance (cd / m 2 )-Current density (mA / cm 2 ) characteristics are shown in Figure 7. Degree (cd / m 2 )-voltage (V) characteristics are shown in Fig. 8, and current efficiency (cd / A)-luminance (cd / m 2 ) characteristics, and FIG. 9 shows the current (mA)-voltage (V) characteristics. d / m 2 The main characteristics of the area are shown in Table 2.

[0135] [Table 2]

[0136] FIG. 10 shows the emission spectrum when a current of 0.1 mA is applied to the light-emitting element 1. In FIG. 10, the vertical axis indicates the emission intensity and the horizontal axis indicates the emission wavelength (nm).

[0137] The light-emitting element 1 in this embodiment has a reflective electrode made of an aluminum-titanium alloy and a semi-reflective surface made of I Since the interface is between the TSO and air, the optical thickness L between these electrodes is 664 nm. = nλ / 2, so when n=2, λ=664 nm is emitted, and when n=3, λ=443 nm is emitted. This is the resonant wavelength of the element 1. Looking at FIG. 10, at a wavelength corresponding to this wavelength, It has been confirmed that the light emitting device 1 has a peak and a resonant structure at multiple wavelengths. The CIE1931 chromaticity coordinate diagram of the light-emitting element 1 is shown in FIG. The parts marked with red represent the chromaticity of the light-emitting element at each measurement voltage. The optical element 1 is a light-emitting element having a resonant structure at multiple wavelengths, and is therefore suitable for lighting applications. It was also found that the light-emitting element emitted light with a given color temperature.

[0138] (Reference example) In this reference example, materials used in the light-emitting element 1 of the example will be described.

[0139] <Synthesis example of 1,6mMemFLPAPrn> The material of the light-emitting element 1 was N'-bis(3-methylphenyl)-N,N'-bis[3-( 9-phenyl-9H-fluoren-9-yl)phenyl]-pyrene-1,6-diamine ( An example of synthesizing 1,6mMemFLPAPrn (abbreviation: 1,6mMemFLPAPrn) is shown below.

[0140] [Step 1: 3-methylphenyl-3-(9-phenyl-9H-fluoren-9-yl ) Synthesis of phenylamine (abbreviation: mMemFLPA)

[0141] 9-(3-bromophenyl)-9-phenylfluorene 3.2 g (8.1 mmol), Na 2.3 g (24.1 mmol) of thorium tert-butoxide was placed in a 200 mL three-neck flask. The mixture was then poured into a flask and replaced with nitrogen. 0.9 mL (8.3 mmol) of 10% hexanediamine 0.2 mL of the dimethylformamide solution was added. The mixture was heated to 60° C. and bis(dibenzylideneacetone) ) palladium(0) 44.5 mg (0.1 mmol) was added, and the mixture was heated at 80° C. for 2 The mixture was stirred for 1.0 hours. After stirring, Florisil (Wako Pure Chemical Industries, Ltd., Catalog No. 54 0-00135), Celite (Wako Pure Chemical Industries, Ltd., Catalog number: 531-1685 5) The mixture was filtered through alumina with suction to obtain a filtrate. The filtrate was concentrated to obtain a solid, which was then mixed with silane. The mixture was purified by silica gel column chromatography (eluent: hexane:toluene = 1:1). The product was recrystallized from a mixed solvent of toluene and hexane to obtain 2.8 g of the desired white solid in a yield of 82%. The synthesis scheme of step 1 above is shown in (A-1) below.

[0142] [ka]

[0143] [Step 2: Synthesis of 1,6mMemFLPAPrn]

[0144] 0.6 g (1.7 mmol) of 1,6-dibromopyrene, 1.4 g (3. 4mmol), sodium tert-butoxide 0.5g (5.1mmol) in 100 The mixture was placed in a 3-neck flask and the inside of the flask was replaced with nitrogen. 0.2 mL of a 10% hexane solution of tri(tert-butyl)phosphine was added. The mixture was heated to 60°C and 34.9 mg of bis(dibenzylideneacetone)palladium(0) was added. (0.1 mmol) was added and the mixture was stirred at 80° C. for 3.0 hours. Add 400 mL of ethylene and heat. While still hot, pour in Florisil (Wako Pure Chemical Industries, Ltd., Catalog Log number: 540-00135), Celite (Wako Pure Chemical Industries, Ltd., Catalog number: 5 The filtrate was concentrated and filtered through alumina. The obtained solid was purified by silica gel column chromatography (eluent: hexane:toluene = 3 The yellow solid was purified by the method described above. The product was recrystallized from a solvent to give 1.2 g of the desired yellow solid in a yield of 67%.

[0145] The resulting yellow solid (1.0 g) was purified by train sublimation. The preparation conditions were a pressure of 2.2 Pa, argon gas was fed at a flow rate of 5.0 mL / min, and the reaction mixture was stirred for 31 h. The yellow solid was heated at 7°C. After purification by sublimation, 1.0 g of the desired yellow solid was obtained in a yield of 93%. The synthetic scheme of the above step 2 is shown below (A-2).

[0146] [ka]

[0147] Nuclear magnetic resonance (NMR) analysis confirmed that this compound was the target compound, 1,6mMemFLPAP It was confirmed that it was rn.

[0148] The obtained compound 1 The 1 H NMR data is shown below. 1 H NMR (CDCl3,300 MHz): δ=2.21(s,6H), 6.67(d,J=7.2Hz,2H), 6.7 4(d,J=7.2Hz,2H), 7.17-7.23(m,34H), 7.62(d, J=7.8Hz,4H), 7.74(d,J=7.8Hz,2H), 7.86(d,J= 9.0Hz,2H), 8.04(d,J=8.7Hz,4H)

[0149] <Synthesis example of 2mDBTPDBq-II> An example of synthesizing 2mDBTPDBq-II used as the material of the light-emitting element 1 will be described.

[0150] [Synthesis of 2mDBTPDBq-II] The synthetic scheme of 2mDBTPDBq-II is shown in (B-1).

[0151] [ka]

[0152] Add 5.3 g (20 mmol) of 2-chlorodibenzo[f,h]quinoxaline to a 2 L three-neck flask. ), 3-(dibenzothiophen-4-yl)phenylboronic acid 6.1g (20mmol) , tetrakis(triphenylphosphine)palladium(0) 460 mg (0.4 mmol) ), 300 mL of toluene, 20 mL of ethanol, and 20 mL of 2 M potassium carbonate aqueous solution were added. The mixture was degassed by stirring under reduced pressure, and the atmosphere in the flask was replaced with nitrogen. The mixture was stirred at 100°C for 7.5 hours under a nitrogen stream. After cooling to room temperature, the resulting mixture was The mixture was filtered to obtain a white residue. The residue was washed with water and then with ethanol, and then dried. The solid obtained was dissolved in about 600 mL of hot toluene and then filtered through a pad of Celite (Wako Pure Chemical Industries, Ltd.). Co., Ltd., Catalog number: 531-16855), Florisil (Wako Pure Chemical Industries, Ltd. The mixture was filtered through a filter (catalog number: 540-00135) with suction to obtain a colorless and transparent filtrate. The filtrate was concentrated and purified by silica gel column chromatography. The solid obtained here was mixed with acetone and ethanol to obtain a toluene-based elution solvent. After adding alcohol and irradiating it with ultrasound, the resulting suspension was filtered and dried, revealing the target compound. A white powder was obtained in an amount of 7.85 g and a yield of 80%.

[0153] The resulting white powder (4.0 g) was purified by train sublimation. The white powder was heated to 300°C under the conditions of a pressure of 5.0 Pa and an argon flow rate of 5 mL / min. After purification by sublimation, 3.5 g of the target white powder was obtained in a yield of 88%.

[0154] NMR confirmed that this compound was the target, 2mDBTPDBq-II. did.

[0155] The obtained material 1 The 1 H NMR data is shown below. 1 H NMR (CDCl3, 300M Hz):δ(ppm)=7.45-7.52(m,2H),7.59-7.65(m,2 H),7.71-7.91(m,7H),8.20-8.25(m,2H),8.41( d,J=7.8Hz,1H),8.65(d,J=7.5Hz,2H),8.77-8. 78(m,1H),9.23(dd,J=7.2Hz,1.5Hz,1H),9.42( dd,J=7.8Hz,1.5Hz,1H),9.48(s,1H).

[0156] <Synthesis example of [Ir(mppm)2(acac)]> An example of synthesizing Ir(mppm)2(acac) used as the material of the light-emitting element 1 will be described.

[0157] [Step 1: Synthesis of 4-methyl-6-phenylpyrimidine (Hmppm)] First, 4.90 g of 4-chloro-6-methylpyrimidine, 4.80 g of phenylboronic acid, and charcoal were Sodium acetate 4.03g, Bis(triphenylphosphine)palladium(II) dichloride 0.16 g of Pd(PPh3)2Cl2, 20 mL of water, 10 mL of acetonitrile The reaction vessel was filled with argon gas. The material was heated by irradiating it with microwaves (2.45 GHz, 100 W) for 60 minutes. 2.28 g of phenylboronic acid, 2.02 g of sodium carbonate, Pd(PPh3)2Cl2 0.082g, 5mL of water, and 10mL of acetonitrile were placed in a flask and microwaved again ( The solution was heated by irradiating it with a 2.45 GHz 100 W power source for 60 minutes. The extract was diluted with saturated aqueous sodium carbonate, water, The solution was then washed with saturated saline and dried over magnesium sulfate. The solvent was removed from this solution, and the resulting residue was diluted with dichloromethane:ethyl acetate=9: Purify the mixture by silica gel column chromatography using 1 (volume ratio) as the developing solvent to obtain the desired peak. The rimidine derivative Hmppm was obtained (orange oil, 46% yield). A microwave synthesis apparatus (CEM Discover) was used for the synthesis. The synthesis scheme (C-1) is shown below.

[0158] [ka]

[0159] [Step 2; Di-μ-chloro-bis[bis(6-methyl-4-phenylpyrimidinato) Synthesis of [Iridium(III)] (abbreviation: [Ir(mppm)2Cl]2)] Next, 15 mL of 2-ethoxyethanol, 5 mL of water, and Hmppm1 obtained in step 1 above were 0.51g, iridium chloride hydrate (IrCl3·H2O) 1.26g, The flask was then filled with argon. The mixture was irradiated with a 5 GHz 100 W power source for 1 hour to cause a reaction. After the solvent was removed by distillation, the resulting residue was The binuclear complex [Ir(mppm)2Cl]2 was obtained by washing with ethanol and filtering. (Dark green powder, 77% yield). The synthetic scheme of step 2 (C-2) is shown below.

[0160] [ka]

[0161] [Step 3; (acetylacetonato)bis(6-methyl-4-phenylpyrimidinato) Synthesis of Iridium(III) (abbreviation: [Ir(mppm)2(acac)]) Furthermore, 40 mL of 2-ethoxyethanol and the binuclear complex [Ir(mp pm)2Cl]21.84g, acetylacetone 0.48g, sodium carbonate 1.73g The mixture was placed in a recovery flask equipped with a reflux condenser, and the atmosphere in the recovery flask was replaced with argon. The reaction was carried out by irradiating with microwaves (2.45 GHz, 100 W) for 60 minutes. The solvent was removed by distillation. The resulting residue was dissolved in dichloromethane and filtered to remove insoluble matter. The mixture was washed with water, then with saturated saline, and dried over magnesium sulfate. The solvent was removed from this solution, and the resulting residue was diluted with dichloromethane:ethyl acetate= The product was purified by silica gel column chromatography using a 4:1 (volume ratio) developing solvent. After that, the target substance was recrystallized from a mixed solvent of dichloromethane and hexane to obtain a yellow solid. The product was obtained as a powder (yield 44%). The synthesis scheme for step 3 (C-3) is shown below.

[0162] [ka]

[0163] The yellow powder obtained in step 3 above 1 The results of the H-NMR analysis are shown below. From the results, it was found that this compound was the target, (acetylacetonato)bis(6-methyl-4-phenylenediamine). Nylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)2(acac)] ) was found to be obtained.

[0164] 1 H-NMR.δ(CDCl3):1.78(s,6H),2.81(s,6H),5. 24(s,1H),6.37(d,2H),6.77(t,2H),6.85(t,2H ), 7.61-7.63(m,4H), 8.97(s,2H). [Explanation of symbols]

[0165] 101 First electrode 102 Second electrode 103 EL layer 104 Light-emitting layer 105 Light-emitting layer 106 Resonant structure 400 Support Board 401 First electrode 403 EL layer 404 Second electrode 405 Sealing material 406 Sealing material 407 Sealing substrate 408 Space 412 Pad 420 IC chip 702 Anode 704 Cathode 711 Hole injection layer 712 Hole transport layer 713 Light-emitting layer 714 Electron transport layer 715 Electron injection layer 800 First Light Emitting Unit 801 Second Light Emitting Unit 803 Charge generation layer 3000 Tabletop Lighting Device 3001 Ceiling fixed lighting equipment 3002 Wall-mounted lighting device 7501 Lighting Department 7502 Umbrella 7503 Variable Arm 7504 Post 7505 units 7506 Power Switch

Claims

1. A semiconductor device comprising a first substrate, a first electrode, a metal oxide layer, a first layer, a first light-emitting layer, a second layer, a second light-emitting layer, and a second electrode; the first electrode is provided between the first substrate and the metal oxide layer; the first layer is provided between the metal oxide layer and the first light-emitting layer, the second layer is provided between the first light-emitting layer and the second light-emitting layer, the second light-emitting layer is provided between the second layer and the second electrode, the first electrode comprises titanium; the metal oxide layer comprises indium and tin; the first layer comprises an oxide of a transition metal; the second layer comprises an alkali metal compound or an alkaline earth metal compound; the first light-emitting layer and the second light-emitting layer emit light of different wavelengths, an optical distance L between a surface of the conductive metal oxide film on the first electrode side and a surface of the second electrode on the second light-emitting layer side is 650 nm to 1500 nm; a wavelength λ of light from said first and second light-emitting layers both satisfies L=nλ / 2 (n is an integer of 2 or more);

2. In claim 1, The light emitting device, wherein the transition metal oxide is molybdenum oxide.

3. In claim 1 or claim 2, A second substrate is provided. the second electrode is provided between the second light-emitting layer and the second substrate; The first light-emitting layer and the second light-emitting layer are surrounded by the first substrate, the second substrate, and a sealant.

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