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. Furthermore, using the light-emitting element... This invention relates to a light-emitting device, and to electronic equipment and lighting devices using the light-emitting device. [Background technology]

[0002] In recent years, there has been a surge in the development of light-emitting devices using luminescent organic and inorganic compounds as light-emitting materials. In particular, electroluminescent structures having a light-emitting layer containing a light-emitting material between a pair of electrodes. Light-emitting elements, also known as sense elements (hereinafter referred to as EL), are thin, lightweight, fast-responding, and have low DC current. Due to its characteristics such as voltage drive, it is attracting attention as a next-generation flat panel display element. Furthermore, displays using EL elements offer superior contrast and image quality, as well as a wide viewing angle. It also has the following characteristics. Furthermore, because EL elements are planar light sources, liquid crystal displays Applications as a light source for backlights and other lighting are also being considered.

[0003] An EL element comprises a pair of electrodes and a light-emitting layer containing a light-emitting material provided between the pair of electrodes. The EL element emits light of a predetermined color when an electric current is passed through the light-emitting layer, causing the light-emitting material to be excited. It is possible to increase the luminescence brightness of an EL element by passing a high current through the light-emitting layer. It is effective. However, by passing a large current through the EL element, power consumption increases. Furthermore, passing a large current through the light-emitting layer can accelerate the degradation of the EL element.

[0004] Therefore, a light-emitting element in which multiple light-emitting layers are stacked has been proposed (for example, Patent Document 1). Reference 1 describes a system having multiple light-emitting units (hereinafter also referred to as the EL layer in this specification). Moreover, each light-emitting unit discloses a light-emitting element partitioned by a charge generation layer. More specifically a charge generation layer made of vanadium pentoxide is provided on a metal doping layer that functions as an electron injection layer of the first light-emitting unit, and furthermore, a light-emitting element having a structure in which a second light-emitting unit is provided on the charge generation layer is disclosed. The light-emitting element disclosed in Patent Document 1 can emit light with high luminance when a current with the same current density is passed, as compared with a light-emitting element having one light-emitting layer.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] One aspect of the present invention is to provide a light-emitting element capable of emitting light with high luminance as one of the problems.

[0007] Another aspect of the present invention is to provide a long-life light-emitting element as one of the problems.

[0008] Another aspect of the present invention is to provide a light-emitting element capable of being driven at a low voltage as one of the problems.

[0009] Another aspect of the present invention is to provide a light-emitting device with reduced power consumption as one of the problems.

[0010] Another aspect of the present invention is to provide an electronic device or a lighting device with reduced power consumption as one of the problems.

Means for Solving the Problems

[0011] One aspect of the present invention has n (where n is a natural number of 2 or more) layers of EL between the anode and the cathode, Between the m-th (where m is a natural number, 1 ≤ m ≤ n-1)th EL layer and the m+1th EL layer from the pole, A first layer containing a first donor substance, in contact with the mth EL layer, and an electric layer in contact with the first layer. A second layer containing a subtransporting substance and a second donor substance, and the second layer and the m+1th EL A light-emitting element having a third layer in contact with the layer, which contains a hole-transporting material and an acceptor material. He is a child.

[0012] Furthermore, one aspect of the present invention has n (where n is a natural number of 2 or more) layers of EL between the anode and the cathode. And between the m-th (m is a natural number, 1 ≤ m ≤ n-1)th EL layer and the m+1th EL layer from the anode It contains a first electron transport material and a first donor material that are in contact with the mth EL layer. Layer 1 and the first layer in contact with the first electron-transporting material, the second layer having a lower lowest empty molecular orbital level than the first electron-transporting material. A second layer containing two electron-transporting materials and a second donor material, and the second layer and the m+1th A third layer containing a hole transporting material and an acceptor material, which is in contact with the EL layer. It is a light-emitting element.

[0013] Furthermore, one aspect of the present invention is a light-emitting device fabricated using the aforementioned light-emitting element.

[0014] Furthermore, one aspect of the present invention is an electronic device including the aforementioned light-emitting device.

[0015] Furthermore, one aspect of the present invention is a lighting device including the aforementioned light-emitting device. A lighting device is a light source that can be controlled to turn on and off, and it affects the scene, the object being viewed, and the surrounding environment. To illuminate the surrounding area so that it is clearly visible, or to transmit information through visual signals, etc., light is used by humans. This device is intended to be useful in everyday life.

[0016] In this specification, ordinal numbers such as "1st" or "2nd" are used for convenience. This does not indicate the order of processes or the order of stacking. Furthermore, the invention is not specified in this specification. This does not indicate a specific name as a matter for the purpose of [doing something]. [Effects of the Invention]

[0017] A light-emitting element according to one aspect of the present invention has multiple EL layers. Therefore, high-brightness light emission is possible. be.

[0018] Furthermore, a light-emitting element according to one aspect of the present invention has a plurality of EL layers. This can improve the lifespan when high-brightness light emission is performed.

[0019] Furthermore, a light-emitting element according to one aspect of the present invention enables good carrier movement between multiple EL layers. It has a configuration that allows for this. Therefore, the driving voltage of the light-emitting element can be reduced.

[0020] Furthermore, a light-emitting device according to one aspect of the present invention has a light-emitting element with a reduced driving voltage. Therefore, the power consumption of the light-emitting device can be reduced.

[0021] Furthermore, an electronic device or lighting device according to one aspect of the present invention has a light-emitting device with reduced power consumption. Therefore, the power consumption of the electronic device or lighting device can be reduced. [Brief explanation of the drawing]

[0022] [Figure 1] A diagram showing an example of the element structure and band diagram of the light-emitting device described in Embodiment 1. [Figure 2] A diagram showing an example of the element structure and band diagram of the light-emitting device described in Embodiment 2. [Figure 3] A diagram showing an example of the element structure and band diagram of the light-emitting device described in Embodiment 3. [Figure 4] A diagram showing an example of the element structure of the light-emitting device described in Embodiment 4. [Figure 5] A diagram showing an example of the element structure and emission spectrum of the light-emitting device described in Embodiment 5. [Figure 6] A diagram showing an active matrix type light-emitting device described in Embodiment 6. [Figure 7] A diagram showing a passive matrix type light-emitting device described in Embodiment 6. [Figure 8] A diagram showing the electronic device described in Embodiment 7. [Figure 9] A diagram showing the lighting device described in Embodiment 8. [Figure 10] A diagram showing the lighting device described in Embodiment 8. [Figure 11] A diagram showing the element structure of the light-emitting device described in Examples 1 and 2. [Figure 12] A diagram showing the characteristics of the light-emitting element described in Example 1. [Figure 13] A diagram showing the characteristics of the light-emitting element described in Example 1. [Figure 14] A diagram showing the characteristics of the light-emitting element described in Example 2. [Figure 15] A diagram showing the characteristics of the light-emitting element described in Example 2. [Figure 16] A diagram showing the characteristics of the light-emitting element described in Example 3. [Figure 17] A diagram showing the characteristics of the light-emitting element described in Example 3. [Modes for carrying out the invention]

[0023] The embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention The present invention is not limited to the following description, and its form may not depart from the spirit and scope of the present invention. It will be readily apparent to those skilled in the art that the details can be modified in various ways. Therefore, The present invention is not limited to the embodiments described below.

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

[0025] The light-emitting element shown in Figure 1(A) has a light-emitting region between a pair of electrodes (anode 101, cathode 102). It includes a first EL layer 103 and a second EL layer 107. In addition, the light-emitting element is positive From the pole 101 side, the electron injection buffer layer 104 in contact with the first EL layer 103, electron injection buffer The electron relay layer 105 in contact with the buffer layer 104, and the electron 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 provides an injection barrier when injecting electrons into the first EL layer 103. This layer is intended to relax the electrons and improve the electron injection efficiency into the first EL layer 103. In this configuration, the electron injection buffer layer 104 is composed of a donor substance.

[0027] The electron relay layer 105 also aims to rapidly deliver electrons to the electron injection buffer layer 104. This is a layer. In this embodiment, the electron relay layer 105 is made of an electron transport material and a donor It is composed of an electron-transporting substance. The electron-transporting substance applied to the electron relay layer 105 is In addition to having high electron transport capabilities, its LUMO (Lowest Molecular Orbital) The Unoccupied Molecular Orbital) level is present in this embodiment. In the following, the LUMO level of the first EL layer 103 and the accept in the charge generation layer 106 These are materials that occupy the levels between the acceptor levels of tar-type materials. Specifically, electrons As an electron transport material applied to the relay layer 105, the LUMO level must be -5.0 eV or higher. It is preferable to use a material. Furthermore, an electron transport material applied to the electron relay layer 105 and Therefore, it is preferable to use a material with a LUMO level between -5.0 eV and -3.0 eV. stomach.

[0028] The charge generation layer 106 aims to generate holes and electrons, which are carriers of the light-emitting element. This is a layer. In this embodiment, the charge generation layer 106 is a hole transporting material and accept It is composed of substances containing tar.

[0029] The diagram shown in Figure 1(B) represents the band diagram for the device structure shown in Figure 1(A). In this configuration, 111 is the Fermi level of anode 101, 112 is the Fermi level of 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. The donor level of the material, 115 is the LUMO level of the electron-transporting material in the electron relay layer 105. , 116 is the acceptor level of the acceptor material in the charge generation layer 106, and 117 is The LUMO levels of the second EL layer 107 are shown.

[0030] In Figure 1(B), electrons generated in the charge generation layer 106 are in the electron relay layer 105. It transitions to the LUMO level of the electron-transporting material. Furthermore, via the electron injection buffer layer 104 Then it transitions to the LUMO level of the first EL layer 103. After that, the first EL layer 103 Then, holes injected from the anode 101 and electrons injected from the charge generation layer 106 combine. They combine. As a result, the first EL layer 103 emits light. Similarly, the second EL layer 107... Then, holes injected from the charge generation layer 106 and electrons injected from the cathode 102 are regenerated. They bond together. As a result, the second EL layer 107 emits light.

[0031] The light-emitting element shown in this embodiment is an electron relay containing an electron transport material and a donor material. It has layer 105. The donor material lowers the LUMO level of the electron transport material to a low energy level. It shifts to the side. The electronic relay layer 105 has a lower LUMO level than the first EL layer 103. Because it uses an electron-transporting material with a LUMO level, it is initially located at a relatively low position. The existing LUMO level will be further lowered by the donor substance. As a result, The barrier to the sub-relay layer 105 accepting electrons from the charge generation layer 106 is reduced. The electrons received by the electron relay layer 105 are then subjected to a large amount of energy by the electron injection buffer layer 104. It is rapidly injected into the first EL layer 103 without creating an input barrier. As a result, the light-emitting element This enables low-voltage operation of the child.

[0032] Next, we will discuss specific examples of each of the substances mentioned above.

[0033] The donor material contained in the electron injection buffer layer 104 and the electron relay layer 105 is as follows: Alkali metals, alkaline earth metals, or rare earth metals, or alkali metals, alkali The following are applicable: compounds of earth metals or rare earth metals (including oxides, halides, and carbonates). It is possible to do so. Specifically, lithium (Li), cesium (Cs), magnesium Mg, calcium (Ca), strontium (Sr), europium (Eu), i Examples include metals such as tterbium (Yb) and compounds of these metals. Compounds belonging to this group are preferred due to their high electron injection properties.

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

[0035] A specific example of the above-mentioned perylene derivative is 3,4,9,10-perylenetetracarboxylic acid. Dianhydrous (abbreviated as PTCDA), 3,4,9,10-perylenetetracarboxylic Subenzimidazole (abbreviation: PTCBI), N,N'-dioctyl 3,4,9,10 -Perylenetetracarboxylate diimide (abbreviation: PTCDI-C8H), N,N'-dihex Sil-3,4,9,10-perylenetetracarboxylate diimide (abbreviation: HexPTC), etc. These are some examples.

[0036] A specific example of the above nitrogen-containing condensed aromatic compound is pyrazino[2,3-f][1,10] Phenanthroline-2,3-dicarbonitride (abbreviation: PPDN), 2,3,6,7,1 0,11-Hexacyano-1,4,5,8,9,12-Hexazatriphenylene (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: Examples include F2PYPR). Furthermore, nitrogen-containing condensed aromatic compounds are stable compounds. Therefore, it is preferable as an electron transport material contained in the electron relay layer 105. Also, nitrogen-containing condensation Among aromatic compounds, those containing electron-withdrawing groups such as cyano groups and fluoro groups are applicable. This is preferable because it facilitates the reception of electrons in the electron relay layer 105.

[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-naphthalenetetracarboxylate diimide (abbreviation: N TCDI-C8F), 3',4'-dibutyl-5,5''-bis(dicyanomethylene)- 5,5''-dihydro-2,2':5',2''-terthiophene (abbreviation: DCMT), Methanofullerene (e.g., [6,6]-phenyl C 61 (Methyl butyrate, etc.) It can also be applied as an electron transport material contained in the relay layer 105.

[0038] The hole transporting material contained in the charge generation layer 106 is an aromatic amine compound, carbazol Copolymer derivatives, aromatic hydrocarbons, polymer compounds (oligomers, dendrimers, polymers, etc.) Various organic compounds can be applied, such as those mentioned above. Hole mobility is 1 × 10 -6 cm 2 It is a substance with a saturation level of / Vs or higher.

[0039] A specific example of the above aromatic amine compound is 4,4'-bis[N-(1-naphthyl)- N-phenylaminobiphenyl (abbreviation: NPB) and N,N'-bis(3-methylphenyl) (Lu)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4',4''-Tris(carbazole-9-yl)triphenylamine ( Abbreviation: TCTA), 4,4',4''-tris(N,N-diphenylamino)triphenyl Luamine (abbreviation: 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-phenyl Mino[biphenyl (abbreviation: DPAB), N,N'-bis[4-[bis(3-methylphenyl [aminophenyl]-N,N'-diphenyl-[1,1'-biphenyl]-4,4' -Diamine (abbreviation: DNTPD), 1,3,5-tris[N-(4-diphenylaminophen) Examples include [phenyl]-N-phenylaminobenzene (abbreviation: DPA3B).

[0040] A specific example of the above carbazole derivative is 3-[N-(9-phenylcarbazole- 3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1) ), 3,6-bis[N-(9-phenylcarbazole-3-yl)-N-phenylamino ]-9-phenylcarbazole (abbreviation: PCzPCA2), 3-[N-(1-naphthyl) -N-(9-phenylcarbazole-3-yl)amino]-9-phenylcarbazole( Examples include the abbreviation PCzPCN1). Other examples include 4,4'-di(N-carbazolyl)bi Phenyl (abbreviation: CBP), 1,3,5-Tris[4-(N-carbazolyl)phenyl] Benzene (abbreviation: TCPB), 9-[4-(10-phenyl-9-anthracenyl)phenyl [nyl]-9H-carbazole (abbreviation: CzPA), 1,4-bis[4-(N-carbazoli] Examples include phenyl-2,3,5,6-tetraphenylbenzene.

[0041] A specific example of the above aromatic hydrocarbon is 2-tert-butyl-9,10-di(2-na Phthyl)anthracene (abbreviation: t-BuDNA), 2-tert-butyl-9,10-di (1-Naphthyl)anthracene, 9,10-Bis(3,5-diphenylphenyl)ant Spiral (abbreviation: DPPA), 2-tert-butyl-9,10-bis(4-phenyl phenyl Nyl)anthracene (abbreviation: t-BuDBA), 9,10-di(2-naphthyl)anthracene Cene (abbreviation: DNA), 9,10-diphenylanthracene (abbreviation: DPAnth), 2 -tert-butylanthracene (abbreviation: t-BuAnth), 9,10-bis(4-methyl) (Tyl-1-naphthyl)anthracene (abbreviation: DMNA), 9,10-bis[2-(1-na Phthyl)phenyl]-2-tert-butylanthracene, 9,10-bis[2-(1- 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, 9,9'-bianthryl, 10,10'-diphenyl-9,9'-bi Anthrill, 10,10'-bis(2-phenylphenyl)-9,9'-biantrill, 10,10'-bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9'- Bianthril, anthracene, tetracene, lubren, perylene, 2,5,8,11-te Examples include tert-butyl perylene. In addition, the aromatic hydrocarbon is vinyl It may have a vinyl skeleton. Examples of aromatic hydrocarbons having a vinyl group include 4 ,4'-Bis(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi), 9,10 -Bis[4-(2,2-diphenylvinyl)phenyl]anthracene (abbreviation: DPVPA) Examples include:

[0042] Also, poly(N-vinylcarbazole) (abbreviation: PVK) and poly(4-vinyltriphen By applying polymer compounds such as nylamine (abbreviated as PVTPA) as hole transport substances... It can also be done this way.

[0043] Furthermore, the hole-transporting material mentioned above is 1 × 10 -6 cm 2 Hole mobility of / Vs or greater It is preferable that the material possesses this property. However, if the material has higher hole transport than electron transport, It is also possible to apply other options.

[0044] Furthermore, when the above aromatic hydrocarbons are deposited by vapor deposition, the vapor deposition properties during deposition and From the perspective of film quality after deposition, it is preferable that the number of carbon atoms forming the condensed ring is between 14 and 42. It seems so.

[0045] Accepting materials included in the charge generation layer 106 include transition metal oxides and periodic materials. It is possible to apply oxides of metals belonging to groups 4 through 8 in the table. It contains vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, and oxide Examples include metal oxides such as tungsten, manganese oxide, and rhenium oxide. Oxides are preferred because they have high electron-accepting properties. Furthermore, if the acceptor material is molybdenum oxide It is more preferable to use molybdenum. Furthermore, molybdenum oxide has the characteristic of low hygroscopicity. They are doing it.

[0046] Furthermore, the electron injection buffer layer 104, the electron relay layer 105, and the charge generation layer 106 are constructed. Manufacturing methods include dry processes (e.g., vacuum deposition, sputtering), and wet processes. Regardless of the process (e.g., inkjet method, spin coating method, coating method, etc.), various It is possible to apply the method.

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

[0048] The anode 101 should be a metal with a large work function (specifically, preferably 4.0 eV or higher). It is possible to apply alloys, electrically conductive compounds, and mixtures thereof. Physically, it is indium tin oxide (ITO). Indium oxide containing silicon or silicon oxide, tin oxide, indium oxide Zinc oxide (IZO), tungsten oxide and oxide Examples include conductive metal oxides such as indium oxide containing zinc.

[0049] The thin film of the conductive metal oxide can be fabricated by sputtering. Furthermore, these conductive metal oxides can also be fabricated using methods such as the sol-gel method. For example, indium oxide-zinc oxide (IZO) is 1-20 watts in relation to indium oxide. It can be formed by a sputtering method using a target to which t% zinc oxide has been added. Furthermore, indium oxide containing tungsten oxide and zinc oxide is indium oxide It contains 0.5-5 wt% tungsten oxide and 0.1-1 wt% zinc oxide relative to um. It can be formed using a sputtering method with a target.

[0050] In addition, gold (Au), platinum (Pt), nickel (Ni), tungsten (W), and chromium are also used. (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium Pl (Pd), titanium (Ti), and nitrides thereof (e.g., titanium nitride), and acids Molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, manganese oxide, and It is possible to apply oxides such as titanium dioxide as the anode 101. Also, poly(3 ,4-ethylenedioxythiophene) / poly(styrenesulfonic acid) (abbreviation: PEDOT) Polyaniline / poly(styrene sulfonic acid) (abbreviation: PAni / PSS), etc. It is also possible to apply conductive polymers as part of the first EL layer 103. When a charge generation layer in contact with the anode 101 is provided, various conductive materials are used regardless of the magnitude of the work function. It is possible to apply an electrically charged material to the anode 101. The charge generation layer is as described above. The charge generation layer 106 provided between the first EL layer 103 and the second EL layer 107 is identical. It is possible to apply the configuration.

[0051] For cathode 102, a small work function (specifically, 3.8 eV or less is preferred) is desirable. It is possible to apply metals, alloys, electrically conductive compounds, and mixtures thereof. Specifically, elements belonging to Group 1 or Group 2 of the periodic table, namely lithium. Alkali metals such as (Li), cesium (Cs), magnesium (Mg), calcium (C) a) Alkaline earth metals such as strontium (Sr), and alloys containing them (MgAg (AlLi, etc.), and rare earth metals such as europium (Eu) and ytterbium (Yb). And alloys containing these are examples. Furthermore, alkali metals, alkaline earth metals, and Films of alloys containing these can be formed using vacuum deposition. Alloys containing metallic and alkaline earth metals can also be formed by sputtering. That is the case.

[0052] In addition, compounds of alkali metals, alkaline earth metals, or rare earth metals (for example, fluoride) Lithium (LiF), lithium oxide (LiOx), cesium fluoride (CsF), fluoride Thin films of calcium (CaF2, erbium fluoride (ErF3), etc.) and aluminum, etc. It is also possible to form the cathode 102 by laminating it with a metal film. However, When a charge generation layer in contact with the cathode 102 is provided as part of the EL layer 107 of 2, work It is possible to apply various conductive materials to the cathode 102 regardless of the magnitude of the function. The charge generation layer is provided between the first EL layer 103 and the second EL layer 107 as described above. It is possible to apply the same configuration as the charge generation layer 106.

[0053] In the light-emitting element shown in this embodiment, of the anode 101 and cathode 102, Even if one side is not present, it is sufficient if it transmits the emission wavelength. Transparency is achieved by using a transparent electrode such as ITO. Alternatively, this can be ensured by reducing the thickness of the electrode film, etc.

[0054] Next, we will describe specific examples of the first and second EL layers mentioned above.

[0055] The first EL layer 103 and the second EL layer 107 are light-emitting layers having at least a light-emitting material. It is sufficient that it includes and is composed of. In other words, the first EL layer 103 and the second EL layer 107 are The structure may also consist of a light-emitting layer and layers other than the light-emitting layer stacked together. The light-emitting layer included in 3 and the light-emitting layer included in the second EL layer 107 are different. It is also possible that the first EL layer 103 and the second EL layer 107 are each independently generated It may also be a laminated structure in which the light layer and layers other than the light-emitting layer are stacked.

[0056] Other layers besides the light-emitting layer include a layer containing a hole-injecting material (hole-injection layer) and a layer containing a hole-transporting material. Layers containing (hole transport layer), layers containing electron transport material (electron transport layer), and layers containing electron injection material. Examples include layers (electron injection layers), layers containing bipolar (electron transport and hole transport) materials, etc. These can be combined and configured as appropriate.

[0057] Below, the first EL layer 103 and the second EL layer 107 are a hole injection layer, a hole transport layer, and an luminescence layer. Specific examples of materials constituting each layer when the system is composed of a layer, an electron transport layer, and an electron injection layer are shown. vinegar.

[0058] The hole injection layer is a layer containing a hole-injecting substance. This hole-injecting substance is a molybdenum oxide. Holes in ribdenum, vanadium oxide, ruthenium oxide, tungsten oxide, manganese oxide, etc. Injectable substances are also mentioned. Other examples include phthalocyanine (abbreviated as H2Pc) and copper phthalocyanine. Phthalocyanine compounds such as nin (abbreviated as CuPc), and PEDOT / PSS (abbreviated as Polymers such as (name) can also be used as hole-injecting materials.

[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) (name), and 4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N― Aromatic amine compounds such as phenylaminobiphenyl (abbreviation: BSPB), and PCz PCA1 (abbreviation), PCzPCA2 (abbreviation), PCzPCN1 (abbreviation), CBP (abbreviation) Examples include carbazole derivatives of TCPB (abbreviation) and CzPA (abbreviation). Also, PVK (abbreviation), PVTPA (abbreviation), poly[N-(4-{N'-[4-(4-diphenyl [phenylamino]phenyl-N'-phenylamino}phenyl)methacrylamide] (Abbreviation: PTPDMA), poly[N,N'-bis(4-butylphenyl)-N,N'-bi Poly(phenyl)benzidine (abbreviated as Poly-TPD) is suitable as the hole transport substance. It is also possible to use it. The substances described here are mainly 1 × 10 -6 cm 2 / Vs or better It is a material that possesses pore mobility. However, if the material has higher hole transport than electron transport, then this is... Other materials may also be used. Furthermore, the hole transport layer may be a single layer or made of the above materials. You may also use a material consisting of two or more layers stacked together.

[0060] The luminescent layer is a layer containing a luminescent substance. The luminescent substance may be one of the following fluorescent compounds. Furthermore, phosphorescent compounds can be applied.

[0061] The fluorescent compound in question is 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), 4-(9H-carbazole-9-yl)- 4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGA) PPA), N,9-diphenyl-N-[4-(10-phenyl-9-antryl)phenyl [L]-9H-carbazole-3-amine (abbreviation: PCAPA), perylene, 2,5,8, 11-Tetra-tert-butylperylene (abbreviation: TBP), 4-(10-phenyl-9 -Anthryl)-4'-(9-phenyl-9H-carbazole-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-carbazole-3-amine( Abbreviation: 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phen 2DPAP (abbreviation: 2DPAP) PA), N,N,N',N',N'',N'',N''',N'''-Octaphenyldi Benzo[g,p]chrysen-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 2PCABPhA (abbreviation: 2PCABPhA), N-(9,10-diphenyl-2-amine) (Tryl)-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) [Bazole-9-yl)phenyl]-N-phenylanthracene-2-amine (abbreviation: 2Y GABPhA), N,N,9-triphenylanthracene-9-amine (abbreviation: DPhA) PhA), Coumarin 545T, N,N'-Diphenylquinacridone (Abbreviation: DPQd) Rubren, 5,12-bis(1,1'-biphenyl-4-yl)-6,11-diphenyl Lutetracene (abbreviation: 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]quinoridine-9-yl)ethenyl]-4H-pyran-4-ylidene} Ropanedinitrile (abbreviation: DCM2), N,N,N',N'-tetrakis(4-methylf (Phenyl)tetracene-5,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl Nyl-N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a Fluoranthene-3,10-diamine (abbreviation: p-mPhAFD), 2-{2-isopropyl alcohol Ropyru-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro- 1H,5H-benzo[ij]quinoridine-9-yl)ethenyl]-4H-pyran-4-yl Lydene propanedinitrile (abbreviation: DCJTI), 2-{2-tert-butyl-6- [2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H- Benzo[ij]quinoridine-9-yl)ethenyl]-4H-pyran-4-ylidene}pro Pandinitrile (abbreviation: DCJTB), 2-(2,6-bis{2-[4-(dimethylamide) {[2-(4,6-Difluorophenyl)phenyl]ethenyl}-4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDCM), 2-{2,6-Bis[2-(8-methoxy-1,1,7,7-tetrameth yl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: BisDC JTM), etc. can be mentioned.

[0062] As the phosphorescent compound, bis[2-(4’,6’-difluorophenyl)pyridina 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 linate (abbreviation: Ir(CF₃ppy)₂(pic)), bis[2-(4’,6’-dif luorophenyl)pyridinato-N,C 2’ iridium(III) acetylacetonate <° (abbreviation: FIracac), tris(2-phenylpyridinato)iridium(III)( abbreviation: Ir(ppy)₃), bis(2-phenylpyridinato)iridium(III) ace tylacetonate (abbreviation: Ir(ppy)₂(acac)), bis(benzo[h]quinoli nato)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)pyridinate]iridium(III)acetylacetate Nat (abbreviation: Ir(p-PF-ph)2(acac)), bis(2-phenylbenzoth Azolat-N,C 2’ Iridium(III) acetylacetonate (abbreviation: Ir(bt) )2(acac)), bis[2-(2'-benzo[4,5-α]thienyl)pyridinate- N,C 3’ Iridium(III) acetylacetonate (abbreviation: Ir(btp)2(a) cac)), bis(1-phenylisoquinolinato-N,C) 2’ Iridium(III) Cetyl acetonate (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- Iridium(III) triphenylpyrazinate (abbreviation: Ir(tppr)2(acac) )), 2,3,7,8,12,13,17,18-octaethyl-21H,23H-pol Phylin platinum(II) (abbreviation: PtOEP), Tris(acetylacetonate)(monofe) Nanthroline terbium(III) (abbreviation: Tb(acac)3(Phen)), tori (1,3-diphenyl-1,3-propanedionato)(monophenanthroline)Euro Pium(III) (abbreviation: Eu(DBM)3(Phen)), Tris[1-(2-Tenoy) Europium (-3,3,3-trifluoroacetonate) (monophenanthroline) Examples include III) (abbreviation: Eu(TTA)3(Phen)).

[0063] Furthermore, it is preferable that the light-emitting layer has a structure in which these light-emitting materials are dispersed in the host material. The host materials are NPB (abbreviation), TPD (abbreviation), TCTA (abbreviation), and TDA. Aromatic amine compounds such as TA (abbreviation), MTDATA (abbreviation), BSPB (abbreviation), P CzPCA1 (abbreviation), PCzPCA2 (abbreviation), PCzPCN1 (abbreviation), CBP (abbreviation) Carbazole derivatives such as (name), TCPB (abbreviation), CzPA (abbreviation), and PVK (abbreviation) High levels of pulmonary thromboembolism (TPD), PVPPA (abbreviation), PTPDMA (abbreviation), Poly-TPD (abbreviation), etc. Hole-transporting materials including molecular compounds, and tris(8-quinolinolato)aluminum (abbreviated) Name: Alq), Tris(4-methyl-8-quinolinolato)aluminum (abbreviation: Almq) 3) Bis(10-hydroxybenzo[h]quinolinato)beryllium (abbreviation: BeBq2) ), bis(2-methyl-8-quinolinolate)(4-phenylphenolate)aluminum ( Metal complexes having a quinoline skeleton or benzoquinoline skeleton, such as BAlq (abbreviation), bis [2-(2-hydroxyphenyl)benzoxazolate]zinc (abbreviation: Zn(BOX)2) ), bis[2-(2-hydroxyphenyl)benzothiazolat]zinc (abbreviation: Zn(BT) Metal complexes having oxazole-based or thiazole-based ligands such as Z)2), and 2-(4-Bif Phenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole ( Abbreviation: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4- Oxadiazole-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl [-1,3,4-oxadiazole-2-yl)phenyl]carbazole (abbreviation: CO1 1) 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl) )-1,2,4-triazole (abbreviation: TAZ), vasophenanthroline (abbreviation: BPh en), vasocuproine (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'-bipyri) Examples of electron-transporting materials include din-6,6'-diyl) (abbreviation: PF-BPy). It can be done.

[0064] The electron transport layer is a layer containing an electron-transporting material. The electron-transporting material is Alq. (Abbreviation), Almq3 (Abbreviation), BeBq2 (Abbreviation), and BAlq (Abbreviation), etc. Metal complexes having a phosphorus skeleton or a benzoquinoline skeleton, and Zn(BOX)2 (abbreviation) and Metals having oxazole or thiazole ligands such as Zn(BTZ)2 (abbreviation). Examples include complexes. In addition to metal complexes, there are also PBD (abbreviation) and OXD-7 (abbreviation). CO11 (abbreviation), TAZ (abbreviation), BPhen (abbreviation), BCP (abbreviation), PF- Py (abbreviation), PF-BPy (abbreviation), etc., can also be applied as the electron-transporting material. It is possible. The substances described here are mainly 1 × 10 -6 cm 2 Having an electron mobility of / Vs or greater It is a substance that transports electrons more efficiently than holes. It may also be used. Furthermore, the electron transport layer may be not only a single layer, but also a double layer made of the above material. You may also use a stack of the above materials.

[0065] The electron injection layer is a layer containing an electron-injecting material. Examples of electron-injecting materials include lithium fluoride. Alkaline compounds such as um (LiF), cesium fluoride (CsF), and calcium fluoride (CaF2) Examples include metals, alkaline earth metals, or compounds thereof. Also, electron transport materials. A substance containing alkali metals, alkaline earth metals, or compounds thereof (for example, Alq (abbreviation) containing magnesium (Mg), etc., is used as the electron-injectable substance. It is also possible to apply it in this way. By using such a structure, electrons from cathode 102 This can improve injection efficiency.

[0066] When a charge generation layer is provided in the first EL layer 103 or the second EL layer 107, the charge generation layer is The layer shall contain a hole-transporting material and an acceptor material. The charge generation layer shall be the same. This applies not only when the membrane contains hole-transporting substances and acceptor substances, but also when hole-transporting substances A layer containing a substance and a layer containing an acceptor substance may be stacked. However, stacking is not possible. In the case of a structure, the layer containing the acceptor material is in contact with the anode 101 or the cathode 102. It is made.

[0067] By providing a charge generation layer in the first EL layer 103 or the second EL layer 107, the electrodes It becomes possible to form the anode 101 or cathode 102 without considering the work function of the material being formed. The charge generation layer provided in the first EL layer 103 or the second EL layer 107 is above Similar to the charge generation layer 106 provided between the first EL layer 103 and the second EL layer 107 described above. The composition and materials can be applied. Therefore, the above explanation will be used here. Let's do it this way.

[0068] Furthermore, by appropriately combining and stacking these layers, the first EL layer 103 and Two EL layers 107 can be formed. Also, the first EL layer 103 and the second EL layer As for the formation method of 107, various methods can be used depending on the material used (for example, dry method, wet method, etc.). ) can be selected as appropriate. For example, vacuum deposition, inkjet, or spinco Methods such as the stencil method can be used. Alternatively, different methods may be used to form each layer.

[0069] By combining the materials described above, the light-emitting element shown in this embodiment is fabricated. This is possible. Light emission from the aforementioned light-emitting material can be obtained from the light-emitting element. Therefore, by changing the type of light-emitting material used in the light-emitting layer, various light-emitting colors can be obtained. Furthermore, by using multiple light-emitting materials with different emission colors as the light-emitting material, broad It is also possible to obtain emission with a specific spectrum or white emission.

[0070] In this embodiment, a light-emitting element provided with two EL layers is described. The number of EL layers is not limited to two; it can be two or more, for example, three layers. When a light-emitting element is provided with n (where n is a natural number greater than or equal to 2) layers of EL, m (where m is a natural number, 1 ≤ 1) Between the m≦n-1)th EL layer and the (m+1)th EL layer, electron injection blocks are injected sequentially from the anode side. By stacking a buffer layer, an electron relay layer, and a charge generation layer, the driving voltage of the light-emitting element is reduced. It can be reduced.

[0071] Furthermore, the light-emitting element shown in this embodiment can be fabricated on various substrates. For example, it is possible to apply materials such as glass, plastic, metal sheets, and metal foil. Furthermore, if the light emitted from the light-emitting element is to be extracted from the substrate side, a light-transmitting substrate can be used. However, the substrate must function as a support in the manufacturing process of the light-emitting element. Other options are also acceptable.

[0072] The contents shown in this embodiment may be used in appropriate combination with the contents shown in other embodiments. It is possible to be there.

[0073] (Embodiment 2) In this embodiment, an example of the light-emitting element shown in Embodiment 1 is presented. Specifically, The electron injection buffer layer 104 of the light-emitting element shown in Embodiment 1 is a donor material The case where it is composed of a single layer will be explained using Figures 2(A) and (B).

[0074] The light-emitting element shown in this embodiment consists of a pair of electrodes (anode 101, cathode 101, cathode 101) as shown in Figure 2(A). Between poles 102) a first EL layer 103 and a second EL layer 107, which include an emissive region, are sandwiched. In addition, the light-emitting element has electron injection from the anode 101 side into contact with the first EL layer 103. Buffer layer 104, electron relay layer 105 in contact with electron injection buffer layer 104, and It has an electronic relay layer 105 and a charge generation layer 106 in contact with the second EL layer 107.

[0075] In this embodiment, the anode 101, cathode 102, first EL layer 103, and electron relay layer 105, the charge generation layer 106, and the second EL layer 107 have the configuration described in Embodiment 1. And materials can be used. Therefore, the description of Embodiment 1 will be used here. Let's assume that.

[0076] In this embodiment, the material used for the electron injection buffer layer 104 is lithium Alkali metals such as (Li) and cesium (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) (including halides, carbonates such as lithium carbonate and cesium carbonate), alkaline earth metals Compounds (including oxides, halides, and carbonates), as well as rare earth metal compounds (oxides, halides) Examples include substances with high electron implantation rates, such as ions and carbonates. Because highly injectable substances are stable in air, they offer good productivity and are suitable for mass production. preferable.

[0077] The light-emitting element shown in this embodiment has the above-mentioned metal or as the electron injection buffer layer 104. A single layer of the compound is provided. Furthermore, the thickness of the electron injection buffer layer 104 is driven To avoid voltage increases, it is formed with an extremely thin film thickness (specifically, less than 1 nm). Then, after forming the electron transport layer 108, an electron injection buffer layer 104 is placed on top of the electron transport layer 108. When forming, a portion of the material forming the electron injection buffer layer 104 is the first EL It can also be present in the electron transport layer 108, which is part of layer 103. Furthermore, it can be present in very thin electron transport layers. The input buffer layer 104 is part of the electron relay layer 105 and the first EL layer 103. In other words, it can be said that it exists at the interface of the transmission layer 108. In this embodiment, An electron transport layer 108 is formed in the EL layer 103 so as to be in contact with the electron injection buffer layer 104. It is preferable to accomplish this.

[0078] The diagram shown in Figure 2(B) represents the band diagram for the device structure shown in Figure 2(A). In this process, electrons are injected at 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 (electric The injection barrier between the child transport layers 108 can be mitigated. Therefore, the charge generation layer 106 The electrons generated can be easily injected into the first EL layer 103.

[0079] Furthermore, by adopting the electron injection buffer layer structure shown in this embodiment, 3. The electron injection buffer layer (formed by adding a donor substance to an electron transport substance) Compared to a layer, the driving voltage of the light-emitting element can be reduced.

[0080] The contents shown in this embodiment may be used in appropriate combination with the contents shown in other embodiments. It is possible to be there.

[0081] (Embodiment 3) In this embodiment, an example of the light-emitting element shown in Embodiment 1 is presented. Specifically, The electron injection buffer layer 104 of the light-emitting element shown in Embodiment 1 is an electron transport material The case in which the mixture includes a donor substance will be explained using Figures 3(A) and (B). do.

[0082] The light-emitting element shown in this embodiment consists of a pair of electrodes (anode 101, cathode 101, cathode 101) as shown in Figure 3(A). Between poles 102) a first EL layer 103 and a second EL layer 107, which include an emissive region, are sandwiched. In addition, the light-emitting element has electron injection from the anode 101 side into contact with the first EL layer 103. Buffer layer 104, electron relay layer 105 in contact with electron injection buffer layer 104, and It has an electronic relay layer 105 and a charge generation layer 106 in contact with the second EL layer 107.

[0083] Furthermore, the electron injection buffer layer 104 contains an electron transporting substance and an electron donor substance. In this embodiment, the mass ratio of the electron-transporting material is 0.001 or more and 0.1 or less. It is preferable to add the donor substance in this ratio. This results in an electron injection bag with good film quality. A fur layer 104 is obtained. Furthermore, a highly reactive electron injection buffer layer 104 is obtained. It is possible.

[0084] Anode 101, cathode 102, first EL layer 103, and electron relay layer 1 in this embodiment 05, the charge generation layer 106 and the second EL layer 107 have the configuration described in Embodiment 1 and A substance can be used. Therefore, the description of Embodiment 1 will be used here. do.

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

[0086] In addition to these, polymer compounds such as PF-Py (abbreviation) and PF-BPy (abbreviation) are also electron-based. It can be applied as an electron-transporting material contained in the injection buffer layer 104.

[0087] Furthermore, in this embodiment, the donor substance contained in the electron injection buffer layer 104 and These include alkali metals, alkaline earth metals, rare earth metals, and their compounds (oxides). Examples include halides and carbonates. Also, tetrathianaphthalene (abbreviation: Organic compounds such as TTN, nickerosene, and decamethylnickerosene are used as electron injection buffers. It can also be applied as a donor substance 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 buff. When formed in contact with the buffer layer 104, the electron injection buffer layer 104 is used for electron injection electron transport material and electron transport material used in the electron transport layer 108, which is part of the first EL layer 103 This means that the substances can be the same or different.

[0089] The light-emitting element shown in this embodiment, as shown in Figure 3(A), has a first EL layer 103 and an electron beam Between the ray layers 105, there is an electron injection buffer layer 1 containing an electron transport material and a donor material. A distinctive feature is the inclusion of 04.

[0090] The diagram shown in Figure 3(B) represents the band diagram for the device structure in Figure 3(A). The formation of the fur layer 104 results in the formation of the electronic relay layer 105 and the first EL layer 103 (electric The injection barrier between the child transport layers 108 can be mitigated. Therefore, the charge generation layer 106 The electrons generated can be easily injected into the first EL layer 103.

[0091] The contents shown in this embodiment may be used in appropriate combination with the contents shown in other embodiments. It is possible to be there.

[0092] (Embodiment 4) In this embodiment, an example of the light-emitting element shown in Embodiment 1 is presented. Specifically, Regarding the configuration of the charge generation layer 106 of the light-emitting element shown in Embodiment 1, see Figure 4(A), (B) will be used to explain.

[0093] The light-emitting element shown in this embodiment consists of a pair of electrodes (anode 1) as shown in Figures 4(A) and (B). Between the cathode 102 and the first EL layer 103 and the second EL layer 107, which include an emissive region, are sandwiched. It is made. In addition, the light-emitting element is in contact with the first EL layer 103 from the anode 101 side. Electron injection buffer layer 104, electron relay layer 105 in contact with electron injection buffer layer 104 , and also having an electronic relay layer 105 and a charge generation layer 106 in contact with the second EL layer 107. In Figures 4(A) and (B), the anode 101, cathode 102, first EL layer 103, and electron injection The input buffer layer 104, the electronic relay layer 105, and the second EL layer 107 are, in this embodiment The configurations and materials described in 1 to 3 can be used. Therefore, the embodiments described here We will refer to explanations 1 through 3.

[0094] In the light-emitting element shown in Figures 4(A) and (B), the charge generation layer 106 is made of a hole transport material and It is a layer containing an acceptor material. In addition, the charge generation layer 106 contains a hole transport material. When an acceptor substance extracts an electron from a material, holes and electrons are generated.

[0095] The charge generation layer 106 shown in Figure 4(A) contains a hole transport material and an acceptor material within the same film. It has a structure containing a substance. In this case, the mass ratio to the hole transport substance is 0.1 By adding an acceptor substance in a ratio of 4.0 or less, the charge generation layer 106 This is preferable because it facilitates the generation of carriers.

[0096] Figure 4(A) shows a configuration in which the acceptor substance is doped with a hole transporter substance. Therefore, even when the charge generation layer 106 is made thicker, the increase in the driving voltage can be suppressed. Therefore, it is possible to suppress the rise in the driving voltage of the light-emitting element and improve color purity through optical adjustment. This can be achieved. Furthermore, by making the charge generation layer 106 thicker, short circuits of the light-emitting element can be prevented. It is possible.

[0097] On the other hand, the charge generation layer 106 shown in Figure 4(B) is a hole transport layer in contact with the second EL layer 107. Layer 106a containing a material and layer 10 containing an acceptor material in contact with the electron relay layer 105 It has a structure in which 6b and are stacked. In the charge generation layer 106 of the light-emitting element shown in Figure 4(B) It is formed by the transfer of electrons between a hole-transporting material and an acceptor material. The electron transfer complex consists of a layer 106a containing a hole transporting material and a layer containing an acceptor material. It is formed only at the interface with 106b. Therefore, the light-emitting element shown in Figure 4(B) is a charge-emitting element. Even when the thickness of the raw layer 106 is increased, the formation of visible light absorption bands is less likely to occur, which is preferable. .

[0098] The hole transporting substances included in the charge generation layer 106 include aromatic amine compounds and k Luvazole derivatives, aromatic hydrocarbons, polymer compounds (oligomers, dendrimers, polymers) Various organic compounds can be used, such as (etc.).

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

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

[0101] Specific examples of the above 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]ant 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' -biantryl, 10,10'-diphenyl-9,9'-biantryl, 10,10'- Bis(2-phenylphenyl)-9,9'-biantryl,10,10'-bis[(2, 3,4,5,6-Pentaphenyl)phenyl]-9,9'-bianthryl, anthracene Tetracene, rubrene, perylene, 2,5,8,11-tetra(tert-butyl) Examples include lylen. Furthermore, the aromatic hydrocarbon may have a vinyl skeleton. Examples of aromatic hydrocarbons containing a vinyl group include DPVBi (abbreviation) and DPVP. Examples include A (abbreviation).

[0102] In addition, high molecular compounds such as PVK (abbreviation) and PVTPA (abbreviation) can also be applied as the hole transporting material. It is also possible to apply.

[0103] Furthermore, as the hole transporting material, it is preferably a substance having a hole mobility of 1×10 -6 cm 2 / Vs or more. However, as long as it is a substance with higher hole transportability than electrons, it is also possible to apply other substances. It is also possible to apply other substances.

[0104] When the above aromatic hydrocarbon is formed into a film by vapor deposition, from the viewpoints of vapor deposition properties during vapor deposition and the film quality after film formation, it is more preferable that the number of carbon atoms forming the condensed ring is 14 to 42. It is more preferable. It is more preferable.

[0105] Examples of the acceptor substance contained in the charge generation layer 106 include 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, etc. Also, as the acceptor substance, transition metal oxides can be mentioned. Also, oxides of metals belonging to Groups 4 to 8 in the periodic table of elements can be mentioned. Specifically, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, and rhenium oxide are preferable because they have high electron accepting properties. Furthermore, it is more preferable that the acceptor substance is molybdenum oxide. Note that molybdenum oxide has the characteristic of low hygroscopicity. ano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, etc. Examples of the acceptor substance include transition metal oxides. Examples of the acceptor substance include transition metal oxides. Examples of the acceptor substance include transition metal oxides. chromium, molybdenum oxide, tungsten oxide, manganese oxide, and rhenium oxide are preferable because they have high electron accepting properties. Examples of the acceptor substance include transition metal oxides. Furthermore, it is more preferable that the acceptor substance is molybdenum oxide. Note that molybdenum oxide has the characteristic of low hygroscopicity.

[0106] Note that the content shown in this embodiment can be appropriately combined with the content shown in other embodiments. It can be used in combination.

[0107] (Embodiment 5) In this embodiment, an example of the light-emitting element shown in Embodiment 1 is presented. Specifically, An example of a light-emitting element shown in Embodiment 1 will be explained using Figures 5(A) and (B).

[0108] The light-emitting element shown in this embodiment consists of a pair of electrodes (anode 101, cathode 101, cathode 101) as shown in Figure 5(A). Between poles 102) a first EL layer 103 and a second EL layer 107, which include an emissive region, are sandwiched. In addition, the light-emitting element has electron injection from the anode 101 side into contact with the first EL layer 103. Buffer layer 104, electron relay layer 105 in contact with electron injection buffer layer 104, and It has an electronic relay layer 105 and a charge generation layer 106 in contact with the second EL layer 107.

[0109] In this embodiment, the anode 101, cathode 102, electron injection buffer layer 104, electron ri The Ray layer 105 and the charge generation layer 106 have the configuration and materials described in Embodiments 1 to 4. Therefore, the descriptions of Embodiments 1 to 4 will 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 exhibits an emission spectrum and has a peak in the yellow to orange wavelength region. It also has a second light-emitting layer 103b that exhibits an emission spectrum. The third light-emitting layer 107 exhibits an emission spectrum with a peak in the blue-green to green wavelength region. a and a fourth light-emitting layer 107 exhibiting an emission spectrum with a peak in the orange to red wavelength region. It has b. Note that the first light-emitting layer 103a and the second light-emitting layer 103b are stacked in reverse order. It is also acceptable if the third light-emitting layer 107a and the fourth light-emitting layer 107b are stacked in the reverse order. Good.

[0111] When a bias is applied to such a light-emitting element with the anode 101 side being positive and the cathode 102 side being negative, holes injected from the anode 101 and electrons generated in the charge generation layer 106 and injected through the electron relay layer 105 and the electron injection buffer layer 104 recombine in the first light-emitting layer 103a or the second light-emitting layer 103b. As a result, the first emission 330 is obtained. Further, electrons injected from the cathode 102 and those generated in the charge generation layer 106 and the injected holes recombine in the third light-emitting layer 107a or the fourth light-emitting layer 107b to obtain the second emission 340.

[0112] FIG. 5(B) schematically shows the emission spectra of the first emission 330 and the second emission 340. The first emission 330 is the combined emission from both the first light-emitting layer 103a and the second light-emitting layer 103b. Therefore, it shows an emission spectrum having peaks in both the blue to cyan wavelength region and the yellow to orange wavelength region. That is, the first EL layer 103 exhibits two-wavelength type white or white-like emission. Also, the second emission 340 is the combined emission from both the third light-emitting layer 107a and the fourth light-emitting layer 107b. Therefore, it shows an emission spectrum having peaks in both the cyan to green wavelength region and the orange to red wavelength region. That is, the second EL layer 107 exhibits two-wavelength type white or white-like emission different from that of the first EL layer 1 03.

[0113] Therefore, the light-emitting element in this embodiment has the first emission 330 and the second emission 34 As a result of the superposition of zeros, the wavelength ranges are blue to blue-green, blue-green to green, and yellow to orange. Emissions covering the wavelength range from orange to red are obtained.

[0114] For example, the first light-emitting layer 103a (has an emission spectrum with a peak in the blue to blue-green wavelength region) Even if the luminescence (showing the torque) changes due to deterioration over time or current density, the luminescence Since the contribution of the first light-emitting layer 103a to the entire vector is about 1 / 4, the chromaticity shift occurs. It can be done in a relatively small size.

[0115] In addition, in the above explanation, the first EL layer 103 is in the blue to blue-green wavelength region and yellow to orange. The emission spectrum exhibits peaks in both wavelength regions of the color, and the second EL layer 107 is blue-green. An emission spectrum having peaks in both the wavelength region from green to orange and the wavelength region from orange to red. The example shown illustrates this point, but the reverse relationship is also valid. That is, the second EL layer 107 exhibits emission with peaks in both the blue to blue-green wavelength region and the yellow to orange wavelength region. The spectrum shows that the first EL layer 103 is in the blue-green to green wavelength region and the orange to red wavelength region. The configuration may also show an emission spectrum with peaks in both regions. 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, regarding the use of a light-emitting organic compound in the EL layer of the light-emitting element shown in this embodiment... The substances that can be used will be explained. However, the substances that can be applied to the light-emitting element shown in this embodiment are... It is not limited to these.

[0117] Blue to blue-green luminescence is produced by, for example, perylene, TBP (abbreviation), and 9,10-diphenyl By using materials such as tranthene as guest materials and dispersing them in a suitable host material, it can be obtained. It can also be used. In addition, styryl arylene derivatives such as DPVBi (abbreviation), or DNA (abbreviation) It can be obtained from anthracene derivatives such as t-BuDNA (abbreviated as ) and t-BuDNA (abbreviated as ). Alternatively, polymers such as poly(9,9-dioctylfluorene) may be used. The guest materials for light include YGA2S (abbreviation) and N,N'-diphenyl-N,N'-bi Su(9-phenyl-9H-carbazole-3-yl)stilbene-4,4'-diamine( Examples include styrylamine derivatives such as PCA2S (abbreviation). In particular, YGA2S (abbreviation) ) has a peak around 450 nm, which is preferable. Also, as a host material, Tracene derivatives are preferred, and t-BuDNA (abbreviation) and CzPA (abbreviation) are preferred. In particular, CzPA (abbreviation) is preferred because it is electrochemically stable.

[0118] The blue-green to green luminescence is caused 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. Also, BAlq (abbreviation), Z n(BTZ)2 (abbreviation), bis(2-methyl-8-quinolinolato)chlorogallium(Ga It can also be obtained from metal complexes such as (mq)2Cl. Furthermore, poly(p-phenylene) Polymers such as vinylene may also be used. Furthermore, the above-mentioned perylene or TBP (abbreviation) may be used in 5w It can also be obtained by dispersing it in a suitable host material at a high concentration of t% or more. For the green-colored luminescent layer, anthracene derivatives yield highly efficient luminescence as guest materials. Therefore, it is preferable. For example, by using DPABPA (abbreviation), highly efficient blue-green emission can be achieved. Light is obtained. In addition, anthracene derivatives with an amino group substituted at the 2nd position produce highly efficient green light. It is preferable because light can be obtained, and 2PCAPA (abbreviation) is particularly preferred because it has a long lifespan. Anthracene derivatives are preferred as the host material, and the aforementioned CzPA (abbreviation) It is preferable because it is electrochemically stable. Also, by combining green and blue light emission, blue or When fabricating a light-emitting element with two peaks in the green wavelength region, the host of the blue light-emitting layer Using an electron-transporting anthracene derivative such as CzPA (abbreviation), the host of the green light-emitting layer When a hole-transporting aromatic amine compound such as NPB (abbreviation) is used, the blue light-emitting layer and This is preferable because light emission is obtained at the interface with the green light-emitting layer. In other words, in this case, 2PCAPA( As a host for green light-emitting materials such as (abbreviation), aromatic aminerals such as NPB (abbreviation) A blend is preferable.

[0119] Yellow to orange light emission is seen in, for example, Rubren, DCM1 (abbreviation), DCM2 (abbreviation), and Bis. [2-(2-thienyl)pyridinato]acetylacetonatoiridium(Ir(thp)2) (acac), bis(2-phenylquinolinato)acetylacetonatoiridium (Ir (pq)2(acac)) and similar materials are used as guest materials and distributed across suitable host materials. This is obtained by using a tetracene derivative such as rubrene as a guest material. It is preferable because it is highly efficient and chemically stable. In this case, the host material is NPB( Aromatic amine compounds such as (abbreviated) are preferred. Other host materials include bis(8-k (Norinolat) zinc (abbreviation: Znq2) and bis[2-cinnamoyl-8-quinorinolat] adipose Metal complexes such as lead (abbreviated as Znsq2) can be used. Also, poly(2,5-di Polymers such as alkoxy-1,4-phenylenevinylene may also be used.

[0120] Orange to red luminescence is seen, for example, in BisDCM (abbreviation) and 4-(dicyanomethylene)-2. ,6-Bis[2-(jurolidine-9-yl)ethynyl]-4H-pyranDCM1),2 -{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[i j]Quinoridine-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinite Lil (abbreviation: DCM2), Ir(thp)2(acac) (abbreviation), etc. are used as guest materials. It is obtained by using it and dispersing it in a suitable host material. Znq2 (abbreviation) and Zn It can also be obtained from metal complexes such as sq2 (abbreviation). Furthermore, poly(3-alkylthio Polymers such as fen may also be used. As a guest material that exhibits red light emission, BisDC Examples include M (abbreviation), DCM2 (abbreviation), DCJTI (abbreviation), and BisDCJTM (abbreviation). 4H-pyran derivatives are highly efficient and preferred. In particular, DCJTI (abbreviation) and BisD CJTM (abbreviation) is preferred because it has an emission peak around 620 nm.

[0121] In the above configuration, a suitable host material is a luminescent organic compound rather than a luminescent organic compound. The light color should be of a short wavelength or have a large energy gap. Specifically, appropriate materials can be selected from hole transport materials and electron transport materials, as exemplified in Embodiment 1. You can choose from several options. Also, CBP (abbreviation), TCTA (abbreviation), TCPB (abbreviation), etc. You may use it.

[0122] The light-emitting element shown in this embodiment has an emission spectrum of the first EL layer and a second EL layer As a result of the superposition of emission spectra, the blue to blue-green wavelength region and the blue-green to green wavelength region are observed. This produces white light emission that broadly covers the yellow to orange wavelength range and the orange to red wavelength range. .

[0123] Furthermore, by adjusting the film thickness of each layer and intentionally causing slight interference of light, a sharp, protruding pinpoint can be achieved. By suppressing the generation of streaks and creating a trapezoidal emission spectrum, a continuous spectrum is obtained. It may be possible to simulate natural light. Alternatively, the film thickness of each layer can be adjusted to intentionally cause slight interference of light. By doing so, the position of the peak in the emission spectrum can also be changed. The film thickness of each layer is adjusted so that the multiple peak intensities that appear are approximately the same, and furthermore, the relative thicknesses of each layer are adjusted. By narrowing the interval between peaks, a white emission spectrum with a more trapezoidal shape is produced. It can be obtained.

[0124] In this embodiment, each of the multiple light-emitting layers is a complementary color to each other. This shows an EL layer that produces white light emission by superimposing different light emission colors. Next, we will explain the specific configuration of the EL layer that exhibits white light emission due to the complementary color relationship.

[0125] The EL layer provided in the light-emitting element shown in this embodiment is, for example, a hole transporting material and a first A first layer containing a light-emitting material, a second layer containing a hole-transporting material and a second light-emitting material, and A structure in which a third layer containing a particle transporting material and a second light-emitting material is stacked sequentially from the anode 101. It can be considered a success.

[0126] In the EL layer of the light-emitting element shown in this embodiment, in order to obtain white light emission, the first light emission Both the material and the second light-emitting material must emit light. Therefore, carriers within the EL layer To regulate the transport properties, hole-transporting materials and electron-transporting materials are both used as host materials. It is preferable to use a hole transporting material or an electron transporting material that can be used in the EL layer. As the transportable substance, the substances exemplified in Embodiment 1 can be used as appropriate.

[0127] Furthermore, the first and second light-emitting materials are materials whose respective emission colors are complementary. The quality can be selected and used. Complementary color relationships include blue and yellow, or blue-green and Examples include red. Substances that emit blue, yellow, blue-green, and red light include, for example, You can select an appropriate light-emitting material from the list above. Note that the emission wavelength of the second light-emitting material is... By setting the emission wavelength of the second light-emitting material to be shorter than the emission wavelength of the first light-emitting material, the excitation energy of the second light-emitting material is A portion of the energy can be transferred to the first light-emitting material, causing the first light-emitting material to emit light. Therefore, in the light-emitting element of this embodiment, the emission peak wavelength of the second light-emitting material is Preferably, the wavelength is shorter than the emission peak wavelength of the first light-emitting material.

[0128] The light-emitting element configuration shown in this embodiment involves light emission from a first light-emitting material and light emission from a second light-emitting material. Both types of luminescence are obtained, and the luminescence colors of the first and second luminescent materials are complementary to each other. Because of the relationship, white light emission is obtained. Also, by using the light-emitting element configuration shown in this embodiment... This allows for the creation of light-emitting elements with a long lifespan.

[0129] The contents shown in this embodiment may be used in appropriate combination with the contents shown in other embodiments. It is possible to be there.

[0130] (Embodiment 6) In this embodiment, one aspect of a light-emitting device including the light-emitting element shown in Embodiments 1 to 5 is described below. Next, we will explain using Figure 6. Figure 6 is a cross-sectional view of the light-emitting device.

[0131] In Figure 6, the light-emitting device of this embodiment includes a substrate 10 and a light-emitting device provided on the substrate 10. It has an element 12 and a transistor 11. The light-emitting element 12 has a first electrode 13 and a second electrode A layer 15 containing an organic compound is located between the poles 14. The layer 15 containing the organic compound is n (where n is 2 The system has the above number of EL layers (where m is a natural number, 1 ≤ m ≤ n-1), and the m-th EL layer and ( Between the m+1)th EL layers, there is an electron injection buffer layer in contact with the mth EL layer, and electron An electron relay layer in contact with the injection buffer layer, and the electron relay layer and the (m+1)th EL layer It has a charge generation layer in contact with it. In addition, each EL layer is provided with at least an emissive layer. In addition to the light-emitting layer, a hole injection layer, hole transport layer, electron transport layer, or electron injection layer is appropriately provided. The configuration is as follows: That is, the light-emitting element 12 is the light-emitting element as shown in Embodiments 1 to 5. It is an element. The drain region of transistor 11 and the first electrode 13 are connected by the first interlayer insulating film 16 They are electrically connected by wiring 17 that passes through a, 16b, and 16c. The optical element 12 is separated from another light-emitting element located adjacent to it by a partition layer 18. Yes, they are.

[0132] Furthermore, the transistor 11 shown in Figure 6 has a gate electrode on the opposite side of the substrate, with the semiconductor layer at the center. It is a top-gate type with poles. However, regarding the structure of transistor 11 There are no particular limitations; for example, a bottom-gate type would also be acceptable. Also, in the case of a bottom-gate type... This type has a protective film formed on the semiconductor layer that forms the channel (channel-protected type). Alternatively, a channel may be formed in which a part of the semiconductor layer forming the channel is concave (channel etching). (Type) is also acceptable.

[0133] Furthermore, the semiconductor layer material constituting the transistor 11 is silicon (Si) and gel. Lumanium (Ge) and other Group 14 elements in the periodic table, gallium arsenide, and indium These are substances that exhibit semiconductor properties, such as compounds like phosphorus, and oxides like zinc oxide and tin oxide. Any material may be used as long as it meets the requirements. In addition, the semiconductor layer may have a crystalline structure or an amorphous structure. Either structure is acceptable.

[0134] Furthermore, oxides exhibiting semiconductor properties (oxide semiconductors) include indium, gallium, A composite oxide of elements selected from aluminum, zinc, and tin can be used. Zinc oxide (ZnO), indium oxide (IZO) containing zinc oxide c Oxide), as well as oxides consisting of indium oxide, gallium oxide, and zinc oxide. (IGZO: Indium Gallium Zinc Oxide) is an example of this. This is possible. Furthermore, specific examples of semiconductor layers with a crystalline structure include single-crystal semiconductors and polycrystalline semiconductors. Examples include conductors or microcrystalline semiconductors. These are formed by laser crystallization. It can be made from materials, or, for example, formed by crystallization using a solid-phase growth method with nickel, etc. It can be anything.

[0135] In this specification, a microcrystalline semiconductor is defined as an amorphous semiconductor when considering Gibbs free energy. It belongs to a metastable state intermediate between a solid crystal and a single crystal. In other words, it is stable in terms of free energy. A semiconductor having a distinct third state, possessing short-range order and lattice distortion. Microcrystalline silicon, a typical example of a conductor, exhibits a Raman spectrum that differs from that of single-crystal silicon. 20cm -1 It is shifted to a lower wavenumber side. That is, 520c, which represents single-crystal silicon. m -1 And 480 cm² showing amorphous silicon -1 Between the Ramanspe of microcrystalline silicon There is a peak in the clef. Also, hydrogen is used to terminate the unbonded (dangling bond). It contains at least 1 atomic percent or more of halogen. Furthermore, helium, aluminum Adding noble gas elements such as gon, krypton, and neon further enhances lattice distortion. This increases stability and allows for the creation of a high-quality microcrystalline semiconductor layer.

[0136] Furthermore, when the semiconductor layer is formed from an amorphous material, such as amorphous silicon... This includes transistor 11 and other transistors (which constitute a circuit for driving the light-emitting element). A light-emitting device having a circuit composed entirely of N-channel transistors. This is preferable because it simplifies the manufacturing process of the light-emitting device. Also, oxidation Zinc (ZnO), indium oxide (IZO) containing zinc oxide, indium oxide and gallium oxide Oxides composed of um and zinc oxide (IGZO), for example, are N-type semiconductors. Therefore, A transistor in which these oxides are applied to a semiconductor layer becomes an N-channel type. The configuration consists of a circuit composed of either an N-channel or P-channel transistor. It may be a light-emitting device having either transistors or a light-emitting device having a circuit composed of both transistors. good.

[0137] Furthermore, the first interlayer insulating film 16a-16c can also be multilayered as shown in Figures 6(A) and (C). That's fine, a single layer is also acceptable. Note that the first interlayer insulating film 16a is made of silicon oxide or silicon nitride. It consists of inorganic materials, and the first interlayer insulating film 16b is made of acrylic, siloxane (silicon (Si (An organic group whose skeletal structure is formed by a bond between a hydrogen atom and oxygen (O), and whose substituents include at least one hydrogen atom.) It consists of a self-planar material such as silicon oxide that can be coated and formed into a film. Furthermore, between the first layers The insulating film 16c is a silicon nitride film containing argon (Ar). There are no particular limitations on the materials used; other materials may be used besides those mentioned here. Layers made of materials other than those mentioned above may be further combined. In this way, the first interlayer insulating film can be further combined. 16a to 16c may be formed using both inorganic and organic materials, or inorganic It may be formed using either a membrane or an organic membrane.

[0138] The partition layer 18 is preferably shaped such that the radius of curvature changes continuously at the edge. Furthermore, the partition layer 18 is formed using acrylic, siloxane, silicon oxide, etc. This is possible. Furthermore, the partition layer 18 is formed from either an inorganic film or an organic film. Either one is fine, or it can be formed using both.

[0139] Note that in Figures 6(A) and (C), only the first interlayer insulating film 16a to 16c is transistor 1 Although it is configured to be placed between 1 and the light-emitting element 12, as shown in Figure 6(B), the first interlayer insulating film In addition to 16a to 16c, the configuration may also include second interlayer insulating films 19a and 19b. In the light-emitting device shown in Figure 6(B), the first electrode 13 is connected to the second interlayer insulating film 19a, 19 It passes through b and is electrically connected to wiring 17.

[0140] The second interlayer insulating films 19a and 19b, like the first interlayer insulating films 16a to 16c, can also be multilayered. That's fine, a single layer is also acceptable. The second interlayer insulating film 19a can be acrylic, siloxane, or coated film. It is made of a self-planar material such as silicon oxide. Furthermore, the second interlayer insulating film 19b is It is a silicon nitride film containing argon (Ar). Regarding the materials that make up each layer: There are no particular limitations, and you may use things other than those mentioned here. Layers made of different materials may be further combined. In this way, the second interlayer insulating films 19a and 19b It may be formed using both inorganic and organic materials, or an inorganic film and organic It may also be formed using either one of the membranes.

[0141] In the light-emitting element 12, both the first electrode 13 and the second electrode 14 are translucent. If it is composed of a material, the first electrode 1 is represented by the white arrow in Figure 6(A). Light can be extracted from both side 3 and side 14 of the second electrode. If only the material is translucent, it is represented by the white arrow in Figure 6(B). Thus, light emission can be extracted only from the second electrode 14 side. In this case, the first electrode 13 is composed of a highly reflective material, or a film (reflective film) made of a highly reflective material is the It is preferable that it is located below electrode 13. Also, only electrode 13 is light-transmitting. If it is composed of a substance having properties, as shown by the white arrow in Figure 6(C), Light can be extracted only from the electrode 13 side of electrode 1. In this case, the second electrode 14 reflects light. It is made of a material with a high efficiency, or a reflective film is provided above the second electrode 14. preferable.

[0142] Furthermore, the light-emitting element 12 has a potential higher at the second electrode 14 than at the first electrode 13. A layer 15 containing an organic compound is laminated so that it operates when a voltage is applied. It is acceptable, and the potential of the second electrode 14 should be lower than the potential of the first electrode 13. Even if the layer 15 containing an organic compound is laminated to operate when pressure is applied Good. In the former case, the first electrode 13 is the anode, the second electrode 14 is the cathode, and The transistor 11 is an N-channel transistor. In the latter case, the first electrode 13 is the cathode. The second electrode 14 is the anode, and the transistor 11 is a P-channel type transistor. It is Ta.

[0143] As described above, in this embodiment, the driving of the light-emitting element is controlled by a transistor. I have explained the active matrix type light-emitting device, but in addition, there are transistors and other drive devices. A passive matrix type that drives the light-emitting element without placing the element on the same substrate as the light-emitting element. It may also be a light-emitting device. Figure 7(A) shows the light-emitting elements shown in Embodiments 1 to 5. Figure 7(B) shows a perspective view of a passive matrix type light-emitting device fabricated using the same method. ) is a cross-sectional view along the dashed line XY in Figure 7(A).

[0144] In Figure 7, a light-emitting element 955 is provided between electrodes 952 and 956 on the substrate 951. The light-emitting element 955 is the light-emitting element shown in Embodiments 1 to 5. Electrode 95 The end of 2 is covered with an insulating layer 953. A partition layer 954 is provided on top of the insulating layer 953. It is being cut. The side walls of the partition layer 954 are such that as they get closer to the substrate surface, one side wall and the other It is preferable that the gap between the side wall and the wall becomes narrower as the slope increases. In other words, the partition wall layer 954 The cross-section in the short-side direction is trapezoidal, with the base (facing in the same direction as the surface direction of the insulating layer 953) The side in contact with the insulating layer 953 is the upper side (which faces the same direction as the surface direction of the insulating layer 953, and is insulated It is shorter than the side that does not touch layer 953. In this way, by providing the partition layer 954, static electricity This prevents defects in light-emitting elements caused by factors such as the above. By applying the light-emitting elements shown in Embodiments 1 to 5 to the installation, a low-power light-emitting device can be created. You can obtain a place.

[0145] The light-emitting device shown in this embodiment uses the light-emitting element shown as an example in Embodiments 1 to 5. Therefore, it is a light-emitting device that can emit light with high brightness and operate at low voltage. It is a light-emitting device with low power consumption.

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

[0147] The electronic devices in this embodiment include televisions, video cameras, digital cameras, and go-cameras. Group displays, navigation systems, computers, gaming devices, mobile information terminals End (mobile computer, mobile phone, portable game console or e-book, etc.), recording medium Equipped with an image playback device (specifically, a Digital Versatile Disc (DV) Examples include devices that can play back recording media such as D) and have a display unit capable of displaying the images. Specific examples of these electronic devices are shown in Figure 8.

[0148] Figure 8(A) shows an example of a mobile information terminal device 800. It has a built-in computer and is capable of performing various data processing tasks. As for the 800s of portable information terminal devices, PDAs (Personal Digital Associates) are examples. (Sistance) is one example.

[0149] The portable information terminal device 800 consists of two housings: housing 801 and housing 803. The housing 801 and housing 803 are connected by a connecting section 807 in a foldable manner. Unit 01 incorporates a display unit 802, and the chassis 803 is equipped with a keyboard 805. Of course, the configuration of the mobile information terminal device 800 is not limited to those described above, and may include other auxiliary equipment. The configuration can be configured to include as appropriate. The display unit 802 will be described in Embodiments 1 to 5. It is constructed 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 also has similar characteristics, thus this portable information terminal device has low power consumption. This is being attempted.

[0150] Figure 8(B) shows an example of a digital video camera 810 according to this embodiment. The digital video camera 810 has a display unit 812 integrated into the housing 811, and various other components. An operating section is provided. Note that 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 described in Embodiments 1 to 5. It is constructed by arranging light-emitting elements similar to those described above in a matrix. It has the characteristics of low dynamic voltage, high brightness, and low power consumption. The display unit 812 also has similar characteristics, so this digital video camera 810 has low power consumption. Efforts are being made to reduce electricity consumption.

[0152] Figure 8(C) shows an example of a mobile phone 820 according to this embodiment. 820 consists of two housings, housing 821 and housing 822, and the connecting part 823 It is connected in a more foldable manner. The housing 822 incorporates a display unit 824. The housing 821 is equipped with operation keys 825. The configuration of the mobile phone 820 is particularly This is not limited to the above, and other auxiliary equipment may be provided as appropriate.

[0153] In the mobile phone 820, the display unit 824 is the same as that described in Embodiments 1 to 5. It is composed of various light-emitting elements arranged in a matrix. These light-emitting elements are driven at high brightness. It has the characteristics of low voltage and low power consumption. Since part 824 also has similar characteristics, this mobile phone is designed to have low power consumption. As shown in the above embodiment, as a backlight for a display provided in a mobile phone or the like. You may also use a light-emitting element.

[0154] Figure 8(D) shows an example of a portable computer 830. Computer 83 Unit 0 comprises two enclosures, 831 and 834, which are connected in a way that allows them to be opened and closed. Enclosure 831 has a display The unit 832 is incorporated, and the casing 834 is equipped with a keyboard 833, etc. The configuration of the 830 is not particularly limited, and may include other auxiliary equipment as appropriate. It is possible.

[0155] In the computer 830, the display unit 832 is the same as that described in Embodiments 1 to 5. It is constructed by arranging similar light-emitting elements in a matrix. These light-emitting elements are high-brightness and drive It has the characteristics of low dynamic voltage and low power consumption. Since the display unit 832 also has similar characteristics, this computer is designed to have low power consumption. .

[0156] Figure 8(E) shows an example of the television 840. The television 840 has a housing The display unit 842 is incorporated into 841. The display unit 842 can display video. It is possible. Furthermore, here we show a configuration in which the housing 841 is supported by the stand 843. Yes, they are.

[0157] Television 840 is operated using the control switches (not shown) on the housing 841, or separately This can be done using the remote control unit 850. The key 851 allows you to control the channel and volume, and the information displayed on the display unit 842 is shown. The video can be controlled. In addition, the remote control unit 850 can be controlled by the remote control unit 85 A display unit 852 that displays information starting from 0 may also be provided.

[0158] The Television 840 will be configured to include a receiver, modem, etc. It can receive regular television broadcasts, and also via wired or wireless connection through a modem. By connecting to a communication network, communication can be one-way (sender to receiver) or two-way (sender to receiver). It is also possible to communicate information between believers 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 implemented It is constructed by arranging light-emitting elements similar to those described in Forms 1 to 5 in a matrix. The light-emitting element in question has the characteristics of high brightness, low driving voltage, and low power consumption. The display unit, which is composed of light-emitting elements, also has similar characteristics.

[0160] As described above, the range of applications for light-emitting devices is extremely wide, and these light-emitting devices can be used in electronic equipment in all fields. It can be applied to a device. Furthermore, the light-emitting elements shown in Embodiments 1 to 5 By using a light-emitting device having the following characteristics, a display unit is provided that exhibits high brightness and low power consumption. This will make it possible to provide electronic devices.

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

[0162] Figure 9 shows a lighting device in a room. The desk lamp 900 shown in Figure 9 has a lighting unit 9 It has 01. The lighting unit 901 is fitted with the light-emitting elements shown in Embodiments 1 to 5. The light-emitting element in question has the characteristics of high brightness, low driving voltage, and low power consumption. The lighting unit 901, which is composed of light-emitting elements, also has similar characteristics, so this desk lamp The 900 model is designed for low power consumption. Furthermore, the light-emitting element can be made to have a large area. Therefore, it can also be used as the lighting unit 911 of the ceiling lighting device 910. Furthermore, Since the light-emitting element can be made flexible, the lighting section 9 of the roll-type lighting device 920 It can also be applied to version 21.

[0163] Figure 10(A) shows a traffic light. Traffic light 1000 has a blue light unit 1001 and a yellow light. It has a colored illumination unit 1002 and a red illumination unit 1003. The traffic light 1000 is in the order of blue, yellow, and red. Each corresponding lighting unit has at least one of the light-emitting elements shown in Embodiments 1 to 5. Light-emitting elements have the characteristics of high brightness, low driving voltage, and low power consumption. Since each of the lighting sections corresponding to blue, yellow, and red, which are composed of light-emitting elements, also has the same characteristics, this signal This unit is designed to have low power consumption.

[0164] Figure 10(B) shows an emergency exit sign. The emergency exit sign 1010 consists of a lighting unit and It can be constructed by combining it with a fluorescent plate that has a fluorescent section. Furthermore, it can emit a specific color. It is constructed by combining an illuminated section that emits light and a light-shielding plate with a translucent section shaped as shown in the diagram. It is also possible to... The illumination section of the emergency exit sign 1010 has the light emission shown in Embodiments 1 to 5. The element is applied. This light-emitting element has high brightness, low driving voltage, and low power consumption. It has the following characteristics. The illumination section, which is composed of light-emitting elements, also has the same characteristics. The emergency exit signs are designed to consume less power.

[0165] Figure 10(C) shows a streetlamp. The streetlamp consists of a support 1021 and an illumination unit 1022. It has the following. The illumination unit 1022 is fitted with the light-emitting elements shown in Embodiments 1 to 5. This light-emitting element has the characteristics of high brightness, low driving voltage, and low power consumption. The lighting section, which is composed of light-emitting elements, also has similar characteristics, thus reducing power consumption. This is being attempted.

[0166] As shown in Figure 10(C), power is supplied to the streetlights via the power line 1024 on the utility pole 1023. Voltage can be supplied. However, the method of supplying the power supply voltage is not limited to this. Example For example, a photoelectric converter is provided on the support 1021, and the voltage obtained by the photoelectric converter is used as the power supply. It can also be used as a source of pressure.

[0167] Furthermore, examples of applying the lighting device to portable lighting are shown in Figures 10(D) and 10(E). Figure 10(D) shows the configuration of a mountable light, and Figure 10(E) shows a handheld light. This is a diagram showing the configuration of the unit.

[0168] Figure 10(D) shows a mounting light. The mounting light consists of a mounting part 1031 and It has a lighting unit 1032. The lighting unit 1032 is fixed to the mounting unit 1031. The illumination unit 1032 is fitted with the light-emitting elements shown in Embodiments 1 to 5. The element has the characteristics of high brightness, low driving voltage, and low power consumption. Since the lighting section, which is composed of elements, also has similar characteristics, this attachable light has low power consumption. It is being planned.

[0169] Furthermore, the configuration of the mountable light is not limited to that shown in Figure 10(D), and for example, the mounting part 1031 can be used A flat cord or elastic cord is made into a ring-shaped belt, and the lighting unit 1032 is fixed to the belt. It can also be configured to wrap directly around the head.

[0170] Figure 10(E) shows a handheld light. The handheld light consists of a housing 1041 and The lighting unit 1042 has a lighting unit 1042 and a switch 1043. The light-emitting elements shown in 5 to 5 are applied. These light-emitting elements have high brightness and low driving voltage. It has the characteristic of low power consumption. The lighting unit 1042, which is composed of light-emitting elements, Because they share similar characteristics, this handheld light has been designed to have low power consumption.

[0171] The switch 1043 has the function of controlling the illumination or non-illumination of the lighting unit 1042. Furthermore, the switch 1043 is given a function to adjust the brightness of the illumination unit 1042 when it is lit. It is also possible.

[0172] As described above, the range of applications for light-emitting devices is extremely wide, and these devices can be used in lighting equipment in all fields. It can be applied to the installation. Furthermore, the light-emitting elements shown in Embodiments 1 to 5 By using a lighting device having the following features, a display unit that exhibits high brightness and low power consumption is provided. This makes it possible to provide lighting devices. [Examples]

[0173] In this embodiment, an element-emitting element, which is one aspect of the present invention, will be described with reference to Figure 11. The examples and the chemical formulas of the substances used in Examples 2 and 3 are shown below.

[0174] [ka]

[0175] The following describes the method for manufacturing the light-emitting elements 1 to 4 and the comparative light-emitting element 5 of this embodiment.

[0176] First, let's explain the light-emitting element 1 (see Figure 11(A)). On the substrate 2100, an oxide sulfide is formed. Indium tin oxide containing ricon is deposited by sputtering, and the first electrode 2101 The film was formed. The film thickness was set to 110 nm, and the electrode area was set to 2 mm × 2 mm.

[0177] Next, the first electrode 2101 is formed such that the surface on which the first electrode is formed faces downwards. The substrate 2100 is fixed to a substrate holder provided inside the vacuum deposition apparatus, 10 -4 About Pa After reducing the pressure to the desired level, a hole-transporting substance called NPB (abbreviated) and an a By co-depositing with molybdenum(VI) oxide, which is a receptor material, organic compounds A first charge generation layer 2103a was formed, which includes a composite material made by combining an inorganic compound with a material. The film thickness is 50 nm, and the ratio of NPB (abbreviation) to molybdenum(VI) oxide is the mass ratio. The ratio was adjusted to 4:1 (=NPB:molybdenum oxide). Note that co-evaporation is a method that This is a vapor deposition method in which vapor deposition is carried out simultaneously from multiple evaporation sources within a single processing chamber.

[0178] Next, by a deposition method using resistance heating, NPB (abbreviated) is applied to the first charge generation layer 2103a. A film was deposited to a thickness of 10 nm to form a hole transport layer 2103b.

[0179] Furthermore, by co-depositing CzPA (abbreviation) and 2PCAPA (abbreviation), holes A light-emitting layer 2103c with a thickness of 30 nm was formed on the transport layer 2103b. Here, CzPA The mass ratio of (abbreviation) and 2PCAPA (abbreviation) is 1:0.05 (=CzPA:2PCAPA The mixture was adjusted to be such that ). Note that CzPA (abbreviation) is an electron transport material and is a guest material. 2PCAPA (abbreviated as 2PCAPA) is a substance that emits green light.

[0180] Subsequently, using a resistive heating deposition method, Alq (abbreviation) was deposited onto the light-emitting layer 2103c for 10 minutes. A film was deposited to a thickness of m, and an electron transport layer 2103d was formed. This resulted in the first Charge generation layer 2103a, hole transport layer 2103b, light emission layer 2103c, and electron transport layer 21 A first EL layer 2103 containing 03d was formed.

[0181] Next, by co-depositing BPhen (abbreviation) and lithium (Li), electron transport An electron injection buffer layer 2104 with a thickness of 20 nm was formed on the transport layer 2103d. The mass ratio of BPhen (abbreviation) to lithium (Li) is 1:0.02 (=BPhen:L I adjusted it so that it would be i).

[0182] Next, by co-depositing PTCBI (abbreviation) and lithium (Li), electron injection An electron relay layer 2105 with 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) was adjusted to be the case. Note that the LUMO level of PTCBI (abbreviation) is cyclic The luminometry (CV) measurement results indicate an elevation of approximately -4.0 eV.

[0183] Next, on the electron relay layer 2105, a hole transport material called NPB (abbreviation) and an acceptor By co-depositing molybdenum(VI) oxide, a tar-generating material, a second charge generation layer is created. 2106 was formed. Its film thickness was set to 60 nm, and it was composed of NPB (abbreviation) and molybdenum oxide (VI). The ratio of ) was adjusted to a mass ratio of 4:1 (=NPB: molybdenum oxide).

[0184] Next, a second EL layer 2107 was fabricated on the second charge generation layer 2106. The method involves first depositing NPB onto the second charge generation layer 2106 using a resistive heating deposition method. A film (abbreviated as) was deposited to a thickness of 10 nm to form a hole transport layer 2107a.

[0185] Subsequently, by co-depositing CzPA (abbreviation) and 2PCAPA (abbreviation), holes are formed. A light-emitting layer 2107b with a thickness of 30 nm was formed on the transport layer 2107a. Here, CzPA The mass ratio of (abbreviation) and 2PCAPA (abbreviation) is 1:0.05 (=CzPA:2PCAPA ) was adjusted to be so. In other words, the light-emitting layer 2107b included in the second EL layer 2107 is It has the same configuration as the light-emitting layer 2103c included in the first EL layer 2103.

[0186] Next, Alq (abbreviation) is applied to the light-emitting layer 2107b with a film thickness of 10 nm, followed by BPhen ( An electron transport layer 2107c was formed by depositing (abbreviated) at a 20nm deposition and stacking the layers. By depositing lithium fluoride (LiF) onto the transport layer 2107c with a film thickness of 1 nm, A sub-injection layer 2107d was formed. This resulted in the formation of a hole transport layer 2107a and an emissive layer 2107 b. Forming a second EL layer 2107 including an electron transport layer 2107c and an electron injection layer 2107d. Ta.

[0187] Finally, using a resistive heating deposition method, aluminum (Al) was deposited onto the electron injection layer 2107d. A second electrode 2102 is formed by depositing a film with a thickness of 200 nm. This allowed us to fabricate the light-emitting element 1.

[0188] Next, the light-emitting element 2 will be described. The light-emitting element 2, except for the electronic relay layer 2105, It was fabricated in the same manner as optical element 1. Therefore, here, the light-emitting element 2 other than the electronic relay layer 2105 is used. The configuration and manufacturing method of the light-emitting element 2 shall be described in the above explanation. The electron relay layer 2105 consists of an electron transport material called PPDN (abbreviation) and a donor material. By co-depositing lithium (Li) onto the electron injection buffer layer 2104, 3 An electron relay layer 2105 with a thickness of nm was formed. Here, PPDN (abbreviation) and lithium ( The mass ratio of Li was adjusted to 1:0.02 (=PPDN:Li). The LUMO level of PDN (abbreviation) is determined from the results of cyclic voltammetry (CV) measurements. It is approximately 3.83 eV.

[0189] Next, the light-emitting element 3 will be described. The light-emitting element 3, except for the electronic relay layer 2105, It was fabricated in the same manner as optical element 1. Therefore, here, the light-emitting element 3 other than the electronic relay layer 2105 is used. The configuration and manufacturing method of the light-emitting element 3 shall be described by referring to the above explanation. The electron relay layer 2105 consists of an electron transport material PTCBI (abbreviation) and a donor material By co-depositing with a certain lithium oxide (Li2O), an electron injection buffer layer 210 is created. A 3 nm thick electron relay layer 2105 was formed on 4. Here, PTCBI (abbreviation) The mass ratio of PTCBI to lithium oxide (Li2O) is 1:0.02 (=PTCBI:Li2O). I adjusted it so that it would work.

[0190] Next, the light-emitting element 4 will be described. The light-emitting element 4, except for the electronic relay layer 2105, It was fabricated in the same manner as optical element 1. Therefore, here, the light-emitting element 4 other than the electronic relay layer 2105 is used. The configuration and manufacturing method of the light-emitting element 4 shall be as described above. The electron relay layer 2105 consists of an electron transport material called PPDN (abbreviation) and a donor material. By co-depositing lithium oxide (Li2O), an electron injection buffer layer 2104 is formed. An electron relay layer 2105 with a thickness of 3 nm was formed on top. Here, PPDN (abbreviation) and acid The mass ratio of lithium phosphate (Li2O) is 1:0.02 (=PPDN:Li2O). I adjusted it to that.

[0191] Next, the comparison light-emitting element 5 will be described (see Figure 11(B)). The comparison light-emitting element 5 is This structure is obtained by removing the electronic relay layer 2105 from optical elements 1 to 4, and for the other layers... The comparative light-emitting element 5 was formed using the same manufacturing method as light-emitting elements 1 to 4. In other words, in comparative light-emitting element 5 After forming the electron injection buffer layer 2104, the electron injection buffer layer 2104 is then subjected to A charge generation layer 2106 was formed. Thus, a comparative light-emitting element 5 of this embodiment was obtained.

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

[0193] [Table 1]

[0194] The light-emitting elements 1 to 4 and the comparative light-emitting element 5 obtained as described above were placed in a globe box in a nitrogen atmosphere. After sealing each light-emitting element inside the box to prevent exposure to the atmosphere, these The operating characteristics of the light-emitting element were measured. The measurements were taken at room temperature (maintained at 25°C). It was done in a relaxed atmosphere.

[0195] Figure 12 shows the voltage-luminance characteristics of 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 brightness (cd / m²). 2 It represents luminescence. Figure 13 shows the voltage-current density characteristics of 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 / cm²). 2 ) represents the brightness of each light-emitting element. The brightness is 1000 cd / m². 2 The voltages in the vicinity are shown in Table 2 below.

[0196] [Table 2]

[0197] As shown in Figure 12, the light-emitting elements 1 to 4, which are provided with an electronic relay layer, are compared to the comparative light-emitting element 5. It can be seen that high brightness can be obtained. Also, from Figure 13, the light emission with an electronic relay layer is shown. It can be seen that elements 1 to 4 have a higher current density compared to the comparative light-emitting element 5.

[0198] As described above, the light-emitting elements 1 to 4 of this embodiment have the characteristics of light-emitting elements and function sufficiently. It was confirmed that this was the case. Also, from Table 2, light-emitting elements 1 to 4 are compared to comparative light-emitting element 5. It was confirmed that the light-emitting element can be driven at a low voltage. [Examples]

[0199] In this embodiment, a light-emitting element, which is one aspect of the present invention, will be described with reference to Figure 11. In this embodiment, the light-emitting element and the comparative light-emitting element are the same as the light-emitting element described in Example 1. For the parts that need to be passed through, please refer to the explanation given above.

[0200] The following describes the method for manufacturing the light-emitting elements 6 to 9 and the comparative light-emitting element 10 of this embodiment.

[0201] First, let's explain the light-emitting element 6 (see Figure 11(A)). The light-emitting element 6 in this embodiment is Except for the electron injection buffer layer 2104, the light-emitting element 1 was fabricated in the same manner as shown in Example 1. Therefore, this section describes the configuration and fabrication method of the light-emitting element 6 other than the electron injection buffer layer 2104. For this, refer to the explanation in Example 1. In the light-emitting element 6 of this embodiment, BPhen (abbreviation), an electron transport substance, and lithium oxide (Li2), a donor substance. By co-depositing O) and the electron transport layer 2103d, an electron injection layer with a thickness of 20 nm is formed on the electron transport layer 2103d. A buffer layer 2104 was formed. Here, BPhen (abbreviation) and lithium oxide (Li2O) were used. The mass ratio of ) was adjusted to 1:0.02 (=BPhen:Li2O).

[0202] Next, the light-emitting element 7 will be described. The light-emitting element 7 in this embodiment is an electron injection buffer Except for layer 2104, the light-emitting element 2 was fabricated in the same manner as shown in Example 1. Therefore, here The configuration and manufacturing method of the light-emitting element 7 other than the electron injection buffer layer 2104 are described in the Examples. We will use the explanation in 1. In the light-emitting element 7 of this embodiment, the electron-transporting material is BPhen (abbreviation) and lithium oxide (Li2O), a donor substance, are co-deposited. As a result, an electron injection buffer layer 2104 with a thickness of 20 nm is placed on the electron transport layer 2103d. This formed the following: Here, the mass ratio of BPhen (abbreviation) to lithium oxide (Li2O) is 1: The ratio was adjusted to 0.02 (=BPhen:Li2O).

[0203] Next, the light-emitting element 8 will be described. The light-emitting element 8 in this embodiment is an electron injection buffer Except for layer 2104, the light-emitting element 3 was fabricated in the same manner as shown in Example 1. Therefore, here The configuration and manufacturing method of the light-emitting element 8 other than the electron injection buffer layer 2104 are described in the Examples. We will use the explanation in 1. In the light-emitting element 8 of this embodiment, the electron-transporting material is BPhen (abbreviation) and lithium oxide (Li2O), a donor substance, are co-deposited. As a result, an electron injection buffer layer 2104 with a thickness of 20 nm is placed on the electron transport layer 2103d. This formed the following: Here, the mass ratio of BPhen (abbreviation) to lithium oxide (Li2O) is 1: The ratio was adjusted to 0.02 (=BPhen:Li2O).

[0204] Next, the light-emitting element 9 will be described. The light-emitting element 9 in this embodiment is an electron injection buffer Except for layer 2104, the light-emitting element 4 was fabricated in the same manner as shown in Example 1. Therefore, here The configuration and manufacturing method of the light-emitting element 9 other than the electron injection buffer layer 2104 are described in the Examples. We will use the explanation in 1. In the light-emitting element 9 of this embodiment, the electron-transporting material is BPhen (abbreviation) and lithium oxide (Li2O), a donor substance, are co-deposited. As a result, an electron injection buffer layer 2104 with a thickness of 20 nm is placed on the electron transport layer 2103d. This formed the following: Here, the mass ratio of BPhen (abbreviation) to lithium oxide (Li2O) is 1: The ratio was adjusted to 0.02 (=BPhen:Li2O).

[0205] Next, the comparison light-emitting element 10 will be described (see Figure 11(B)). The comparison light-emitting element 10 is The structure is such that the electronic relay layer 2105 is removed from the light-emitting elements 6 to 9, and the other layers are as follows: Therefore, the comparative light-emitting element 10 was formed using the same manufacturing method as light-emitting elements 6 to 9. Then, after forming the electron injection buffer layer 2104, on the electron injection buffer layer 2104 A second charge generation layer 2106 was formed thereon. Thus, the comparative light-emitting element 10 of this embodiment is I got it.

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

[0207] [Table 3]

[0208] The light-emitting elements 6 to 9 and the comparative light-emitting element 10 obtained above were placed in a globe box under a nitrogen atmosphere. After sealing each light-emitting element within the box to prevent exposure to the atmosphere, The operating characteristics of the light-emitting element were measured. The measurements were taken at room temperature (maintained at 25°C). I went because of the atmosphere.

[0209] Figure 14 shows the voltage-luminance characteristics of light-emitting elements 6 to 9 and the comparative light-emitting element 10. On the horizontal axis, the applied voltage (V) is shown, and the vertical axis is shown, the brightness (cd / m²). 2 It represents luminescence. Figure 15 shows the voltage-current density characteristics of 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 / cm²). 2 ) represents each light-emitting element Brightness is 1000 cd / m² 2 The voltages in the vicinity are shown in Table 4 below.

[0210] [Table 4]

[0211] As shown in Figure 14, the light-emitting elements 6 to 9, which are provided with an electronic relay layer, are compared to the comparative light-emitting element 10. This shows that high brightness can be obtained. Also, from Figure 15, it can be seen that the electron relay layer is provided in the It can be seen that the optical elements 6 to 9 have a higher current density compared to the comparative light-emitting element 10.

[0212] As described above, the light-emitting elements 6 to 9 of this embodiment have obtained the characteristics of light-emitting elements and function sufficiently. It was confirmed that this is possible. Furthermore, the light-emitting elements 6 to 9 are light-emitting elements that can be driven at low voltage. This was confirmed. [Examples]

[0213] In this embodiment, a light-emitting element, which is one aspect of the present invention, will be described with reference to Figure 11. In this embodiment, the light-emitting element and the comparative light-emitting element are the same as the light-emitting element described in Example 1. For the parts that need to be passed through, please refer to the explanation given above.

[0214] The following describes the method for manufacturing the light-emitting element 11 and the comparative light-emitting element 12 of this embodiment.

[0215] First, let's describe the light-emitting element 11 (see Figure 11(A)). The light-emitting element 11 of this embodiment This refers to the electron transport layer 2103d and electron injection buffer layer 2104 of the first EL layer 2103. The outer layer was fabricated in the same manner as the light-emitting element 1 shown in Example 1. Therefore, the electron transport layer 2 is used here. Regarding the configuration and fabrication method of the light-emitting element 11 other than 103d and the electron injection buffer layer 2104 Therefore, we will refer to the explanation of Example 1. In the light-emitting element 11 of this example, On the photolayer 2103c, Alq (abbreviation) is applied in a thickness of 10 nm, followed by BPhen (abbreviation) in a thickness of 20 nm. An electron transport layer 2103d was formed by depositing nm-level material and stacking it. Furthermore, electron transport By depositing lithium oxide (Li2O) at a thickness of 0.1 nm onto layer 2103d, electron injection is achieved. An input buffer layer 2104 was formed. Thus, the light-emitting element 11 of this embodiment was obtained.

[0216] Next, the comparative light-emitting element 12 will be described (see Figure 11(B)). Comparative light emission in this embodiment Element 12 has a structure in which the electronic relay layer 2105 is removed from the light-emitting element 11, and other layers Regarding the comparative light-emitting element 12, it was formed using the same manufacturing method as the light-emitting element 11. After forming the electron injection buffer layer 2104, the electron injection buffer layer 2104 is then subjected to A charge generation layer 2106 was formed. Thus, a comparative light-emitting element 12 of this embodiment 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 comparative light-emitting element 12 obtained as described above are placed in a glove box under a nitrogen atmosphere. After sealing each light-emitting element inside the container to prevent exposure to the atmosphere, these The operating characteristics of the light-emitting element were measured. The measurements were taken in an environment maintained at room temperature (25°C). I went there on a whim.

[0220] Figure 16 shows the voltage-luminance characteristics of the light-emitting element 11 and the comparative light-emitting element 12. The horizontal axis represents the applied voltage (V), and the vertical axis represents the luminance (cd / m²). 2 ) represents a light-emitting element. Figure 17 shows the voltage-current density characteristics of 11 and the comparative light-emitting element 12. In Figure 17, the horizontal axis The vertical axis represents voltage (V), and the vertical axis represents current density (mA / cm²). 2 ) represents. Also, the brightness of each light-emitting element is 1 000 cd / m 2 The voltages in the vicinity are shown in Table 6 below.

[0221] [Table 6]

[0222] As shown in Figure 16, the light-emitting element 11, which is provided with an electronic relay layer, is different from the comparative light-emitting element 12. It can be seen that high brightness can be obtained. Also, from Figure 17, the light-emitting element with an electron relay layer is shown. It can be seen that child 11 has a higher current density compared to the comparative light-emitting element 12.

[0223] As described above, the light-emitting element 11 of this embodiment has the characteristics of a light-emitting element and functions sufficiently. It was confirmed that the light-emitting element 11 is a light-emitting element that can be driven at a low voltage. I was able to confirm it. [Explanation of Symbols]

[0224] 10 circuit boards 11 transistors 12 Light-emitting elements 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 Electron relay layer 106 Charge generation layer 106a Layer containing hole-transporting material 106b Layer containing acceptor material 107 EL layer 107a Third light-emitting layer 107b Fourth luminescent layer 108 Electron transport layer 111 Fermi level of the anode 112 Fermi level of the cathode 113 LUMO levels of the first EL layer 114 Donor levels of donor material in the electron relay layer 115 LUMO levels of electron-transporting materials in electron relay layers 116 Acceptor levels of acceptor materials in charge generation layers 117 LUMO levels of the second EL layer 330 First light emission 340 Second emission 800 Mobile Information Terminal Devices 801 cabinet 802 Display section 803 cabinet 805 Keyboard 807 Connection section 810 Digital Video Camera 811 cabinet 812 Display section 820 Mobile phones 821 cabinet 822 cabinets 823 Connection section 824 Display section 825 Operation Keys 830 Computers 831 cabinet 832 Display section 833 keyboard 834 cabinets 840 Television 841 cabinet 842 Display section 843 Stand 850 Remote Control Unit 851 Operation Keys 852 Display section 900 Tabletop Lighting Device 901 Lighting Department 910 Ceiling lighting fixture 911 Lighting Department 920 Roll-type lighting device 921 Lighting Section 951 circuit board 952 Electrode 953 Insulating layer 954 Partition layer 955 Light-emitting element 956 Electrode 1000 traffic lights 1001 Lighting Section 1002 Lighting Section 1003 Lighting Section 1010 Evacuation exit guide light 1021 Support 1022 Lighting Department 1023 Utility pole 1024 Power transmission lines 1031 Mounting part 1032 Lighting Section 1041 cabinet 1042 Lighting Section 1043 Switch 2100 circuit board 2101 Electrode 2102 Electrode 2103 EL layer 2103a Charge generation layer 2103b Hole transport layer 2103c emissive layer 2103d Electron transport layer 2104 Electron injection buffer layer 2105 Electron relay layer 2106 Charge generation layer 2107 EL layer 2107a Hole transport layer 2107b Emitting layer 2107c Electron transport layer 2107d Electron injection layer

Claims

[Claim 1] The anode and cathode have n (where n is a natural number greater than or equal to 2) layers of EL (electroluminescent) material. Between the m-th (where m is a natural number, 1 ≤ m ≤ n-1)th EL layer and the (m+1)th EL layer from the anode, A first layer containing a first donor substance, in contact with the mth EL layer, A second layer containing an electron-transporting material and a second donor material, in contact with the first layer, The material comprises a third layer containing a hole transporting material and an acceptor material, which is in contact with the second layer and the m+1th EL layer. The LUMO level of the electron-transporting material is between -5.0 eV and -3.0 eV. The LUMO level values ​​mentioned above are obtained from cyclic voltammetry (CV) measurements. The first donor substance is an alkali metal, an alkaline earth metal, a rare earth metal, an alkali metal compound, an alkaline earth metal compound, or a rare earth metal compound. The second donor substance is an alkali metal, alkaline earth metal, rare earth metal, alkali metal compound, alkaline earth metal compound, or rare earth metal compound, which is a light-emitting element.

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