Light emitting element

Abstract

To provide a light emitting element that emits light with high luminance and can be driven at low voltage, and to provide a light emitting device or an electronic device with reduced power consumption.SOLUTION: A light emitting element is provided, having: n (n is a natural number of 2 or more) EL layers between an anode and a cathode, and having, between an m-th EL layer (m is a natural number, 1≤m≤n-1) and an (m+1)-th EL layer, in order from the anode side, a first layer including any of 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, a second layer in contact with the first layer and including a substance with high electron transport properties, and a region which is in contact with the second layer and includes a substance with high positive hole transport properties and an acceptor substance. A light emitting device using this light emitting element and electronic equipment are also provided.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] In recent years, there has been active development of light-emitting devices that use light-emitting organic or inorganic compounds as light-emitting substances. In particular, the structure of a light-emitting element called an electroluminescence (EL) element The structure is simple, consisting of a light-emitting layer containing a light-emitting material between electrodes, and is thin, lightweight, and highly responsive. Due to its characteristics such as high response and low DC voltage operation, it is expected to become a next-generation flat panel display element. In addition, displays using such light-emitting elements have been attracting attention. They also have the characteristics of excellent quality and a wide viewing angle. Therefore, it is also being considered for use as a light source for backlighting of liquid crystal displays and lighting. There are.

[0003] The light-emitting element is a light-emitting material that emits light when a current is applied to a light-emitting layer provided between a pair of electrodes. By exciting the substance, a desired emission color can be obtained. In order to increase the brightness, it is possible to supply a large amount of current to the light-emitting layer, but In addition, passing a large current through the light-emitting layer This may accelerate the deterioration of the light emitting element.

[0004] Therefore, by stacking multiple light-emitting layers and passing a current with the same current density as in the case of a single layer, In addition, light-emitting elements that have high luminance have been proposed (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 3933591 Summary of the Invention [Problem to be solved by the invention]

[0006] In Patent Document 1, a plurality of light-emitting units (hereinafter, also referred to as EL layers in this specification) The present inventors have proposed a light-emitting device having a light-emitting unit partitioned by a charge generating layer. Specifically, a 5-layered fluororesin was formed on the metal doped layer that functions as the electron injection layer of the first light-emitting unit. A charge generating layer made of vanadium oxide is provided, and a second light emitting element is provided through the charge generating layer. A light-emitting device having a structure in which units are stacked is disclosed. However, such a structure In the light-emitting device, at the interface between the metal doping layer and the charge generating layer made of an oxide, This causes interactions between the two, creating a strong electric field at the interface, which requires a high voltage to drive the light-emitting element. .

[0007] In view of the above problems, a light-emitting element that emits light with high luminance and can be driven at a low voltage is provided. Another object of the present invention is to provide a light-emitting device or electronic device with reduced power consumption. One of the goals of the project is to [Means for solving the problem]

[0008] One of the configurations of the light-emitting device disclosed in the present specification is a light-emitting device having n (n is a natural number of 2 or more) between an anode and a cathode. m (m is a natural number, 1≦m≦n-1)th EL layer and (m+1)th Between the first and second EL layers, in order from the anode side, are alkali metals, alkaline earth metals, and rare earth metals. compounds of rare earth metals, alkali metal compounds, alkaline earth metal compounds, or rare earth metal compounds a first layer including a substance having a high electron transporting property and being in contact with the first layer; and a region including a substance having a high hole-transporting property and an acceptor substance, the region being in contact with the layer.

[0009] In addition, another configuration of the light-emitting device disclosed in the present specification is a light-emitting device having n (n is 2 or more) between the anode and the cathode. mth (m is a natural number, 1≦m≦n-1)th EL layer and ( Between the (m+1)th EL layer, in order from the anode side, a material with high electron transport properties and a material with donor properties are A first layer including a substance having a high electron transporting property is in contact with the first layer. A second layer including a substance having a high electron transporting property is in contact with the first layer. and a region including a substance having a high hole-transporting property and an acceptor substance, the region being in contact with the layer.

[0010] In the first layer containing the above-mentioned substance having high electron transport properties and a donor substance, The substance is added in a mass ratio of 0.001 to 0.1 to the substance having high electron transport properties. The donor substance may be an alkali metal, an alkaline earth metal, a rare earth metal, or a fluorine atom. with earth metals, alkali metal compounds, alkaline earth metal compounds, or rare earth metal compounds It is preferable to do so.

[0011] In the above structure, the region containing a substance having a high hole transporting property and a substance having an acceptor property is , the mass ratio of the acceptor to the substance with high hole transporting property is 0.1 or more and 4.0 or less. The area where the material is added. Among the carriers generated in this area, the holes are ( m+1)th EL layer, and the electrons move to the second layer.

[0012] In the above structure, the region containing a substance having a high hole transporting property and a substance having an acceptor property is The region is a region in which a layer containing a substance with high hole transporting properties and a layer containing a substance with acceptor properties are stacked. This is also possible.

[0013] In the above structure, the substance having a high electron transporting property contained in the second layer is preferably The LUMO level is preferably 5.0 eV or more, more preferably -5.0 eV or more and -3.0 eV or less. It is preferable to use a material having the above properties.

[0014] In addition, since the light-emitting element having the above structure can be driven at a low voltage, it can be used as a light-emitting element. The light-emitting devices (image display devices and light-emitting devices) that use this technology can achieve low power consumption. Therefore, a light emitting device using the light emitting element having the above configuration, and a light emitting device using the light emitting device A lighting device and an electronic device are also included as an aspect of the present invention.

[0015] The above configuration solves at least one of the above problems.

[0016] In this specification, the term "light-emitting device" refers to electronic equipment such as an image display device using a light-emitting element. Also, the light emitting element may have a connector, such as an anisotropic conductive film. Usually, TAB (Tape Automated Bonding) tape or TCP ( Module with TAB tape attached. A module with a printed wiring board on the end of a chip or TCP, or a light-emitting element with COG (COG) There are also modules with ICs (integrated circuits) directly mounted using the "hip on glass" method. All of these are included in the light-emitting device.

[0017] In this specification, ordinal numbers such as first and second are used for convenience. It does not indicate the order of steps or the order of layers. It does not indicate a specific name as a matter for the purpose of Effect of the Invention

[0018] It is possible to provide a light emitting element which has a plurality of light emitting layers and can be driven at a low voltage.

[0019] Furthermore, by manufacturing a light emitting device using the above-mentioned light emitting element, power consumption is reduced. A light-emitting device can be provided. In addition, such a light-emitting device can be used in a lighting device or an electronic device. By applying this, it is possible to provide a lighting device or electronic device with low power consumption. [Brief description of the drawings]

[0020] [Figure 1] 1A and 1B are diagrams showing an example of an element structure of a light-emitting element and a band diagram thereof; [Diagram 2] 1A and 1B are diagrams showing an example of an element structure of a light-emitting element and a band diagram thereof; [Diagram 3] 1A and 1B are diagrams showing an example of an element structure of a light-emitting element and a band diagram thereof; [Figure 4] 1A to 1C are diagrams showing an example of an element structure of a light-emitting element. [Diagram 5] FIG. 1 illustrates an active matrix light-emitting device. [Figure 6] FIG. 1 illustrates a passive matrix light-emitting device. [Figure 7] FIG. [Figure 8] FIG. [Figure 9] 1A and 1B show element structures of a light-emitting element of an example and a comparative light-emitting element. [Figure 10] FIG. 2 shows characteristics of the light-emitting element of Example 1. [Figure 11] FIG. 2 shows characteristics of the light-emitting element of Example 1. [Figure 12] 1A and 1B show element structures of a light-emitting element of an example and a comparative light-emitting element. [Figure 13] FIG. 13 shows characteristics of the light-emitting element of Example 2. [Figure 14] FIG. 13 shows characteristics of the light-emitting element of Example 2. [Figure 15] FIG. 13 shows characteristics of the light-emitting element of Example 3. [Figure 16] FIG. 13 shows characteristics of the light-emitting element of Example 3. [Figure 17] FIG. 13 shows characteristics of the light-emitting element of Example 4. [Figure 18] FIG. 13 shows characteristics of the light-emitting element of Example 4. [Figure 19] FIG. 13 shows characteristics of the light-emitting element of Example 5. [Figure 20] FIG. 13 shows characteristics of the light-emitting element of Example 5. [Figure 21] FIG. 13 shows an element structure of a comparative light-emitting element according to Example 6. [Figure 22] FIG. 13 shows characteristics of the light-emitting element of Example 6. [Figure 23] FIG. 13 shows characteristics of the light-emitting element of Example 6. [Figure 24] 1A and 1B are diagrams showing an example of an element structure and an emission spectrum of a light-emitting element. [Diagram 25] FIG. 13 shows characteristics of the light-emitting element of Example 7. [Figure 26] FIG. 13 shows characteristics of the light-emitting element of Example 7. [Figure 27] FIG. 13 shows characteristics of the light-emitting element of Example 8. [Figure 28] FIG. 13 shows characteristics of the light-emitting element of Example 8. [Figure 29] FIG. 13 shows characteristics of the light-emitting element of Example 8. [Diagram 30] FIG. 13 shows characteristics of the light-emitting element of Example 9. [Diagram 31] FIG. 13 shows characteristics of the light-emitting element of Example 9. [Diagram 32] FIG. 13 shows characteristics of the light-emitting element of Example 9. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, the embodiment will be described in detail with reference to the drawings. The present invention is not limited to the following description, and the scope of the present invention is not limited to the following description. It will be readily understood by those skilled in the art that various changes in form and details may be made. The present invention should not be construed as being limited to the description of the embodiments and examples in the specification. In all the drawings for explaining the embodiments, the same parts or parts having similar functions are indicated by the same reference numerals. The symbols are given to the respective components, and the repeated explanation will be omitted.

[0022] (Embodiment 1) In this embodiment, one mode of a light-emitting element will be described with reference to FIG.

[0023] The element structure shown in FIG. 1(A) has a light-emitting region between a pair of electrodes (anode 101 and cathode 102). The first EL layer 103 and the second EL layer 107 are sandwiched. Between the second EL layer 107 and the anode 101 side, an electron injection buffer 104 and an electron relay It has a structure in which a layer 105 and a charge generating region 106 are laminated in this order.

[0024] The charge generation region 106 is a region containing a substance with high hole transporting properties and a substance with acceptor properties. In this state, holes and electrons, which are carriers of the light-emitting element, are generated. The generated holes move to the second EL layer 107, and the electrons move to the electron relay layer 105. In addition, the electron relay layer 105 has a high electron transporting property, and therefore can transport electrons to the electron injection buffer 104. Furthermore, the electron injection buffer 104 can be rapidly delivered to the first EL layer 1 Since the injection barrier when injecting electrons into the first EL layer 103 can be reduced, This can increase the efficiency of electron injection into the semiconductor substrate.

[0025] The electron injection buffer 104 may include alkali metals, alkaline earth metals, rare earth metals, and and their compounds (alkali metal compounds (oxides such as lithium oxide, halides, carbonates, etc.) (including carbonates such as lithium and cesium carbonate), alkaline earth metal compounds (oxides, halides, etc.) compounds of rare earth metals (including oxides, halides, carbonates) It is possible to use a material with high electron injection properties, such as an electron injection buffer. The layer 104 may contain a substance with high electron transporting properties and a donor substance.

[0026] FIG. 1B shows a band diagram of the element structure of FIG. 1A. , 111 is the Fermi level of the anode 101, 112 is the Fermi level of the cathode 102, and 113 is the Fermi level of the anode 101. is the LUMO (Lowest Unoccupied Molecular Orbital) of the first EL layer 103. ed Molecular Orbital) level, 114 is the L UMO level, 115, is the acceptor level of the acceptor in the charge generation region 106; 116 denotes the LUMO level of the second EL layer 107 .

[0027] In FIG. 1B, holes injected from the anode 101 are injected into the first EL layer 103. On the other hand, the electrons generated in the charge generating region 106 are transferred to the electron relay layer 105 and then The electrons are injected into the first EL layer 103 through the electron injection buffer 104, recombine with the holes, and emit light. In addition, the holes generated in the charge generating region 106 move to the second EL layer 107 and emit light. In the EL layer 107 of No. 2, the electrons recombine with the electrons injected from the cathode 102 and emit light.

[0028] In the light-emitting element shown in this embodiment, the electron relay layer 105 is Since the layer functions as a layer that efficiently injects electrons generated in the first EL layer 103, The charge relay layer 105 has a LUMO level that is closer to the acceptor in the charge generation region 106. A material that occupies a level between the acceptor level and the LUMO level of the first EL layer 103. Specifically, it is preferable to use a material having a LUMO level of about -5.0 eV or higher. It is preferable to use a material having a polarity of −5.0 eV or more and −3.0 eV or less. preferable.

[0029] The acceptor material contained in the charge generating region 106 and the electron injection buffer 104 The highly electron injecting or donor substances used in the present invention are those with strong acceptor or donor properties, respectively. Since the charge generating region 106 and the electron injection buffer 104 are in contact with each other, In this case, electrons are exchanged at the interface, and the driving voltage of the light-emitting element increases. A PN junction is formed at the interface between the region 106 and the electron injection buffer 104, However, the driving voltage of the light-emitting element shown in this embodiment mode may increase. The charge generation region 106 and the electron injection buffer 104 are in contact with each other through the electron relay layer 105. The charge generation region 106 can be prevented from being filled with the electrons. The injection buffer 104 contains a substance with high electron injection properties or a donor substance. In addition, the electron relay layer 105 has a LUMO constant in the above range. By using a material having such a structure, the interface with the electron injection buffer 104 is prevented from becoming a strong electric field. The electrons generated in the charge generating region 106 are efficiently transported to the first EL layer 103. can be injected into

[0030] As shown in the band diagram of FIG. 1B, the charge generation region 106 is connected to the electron relay layer 10 The electrons transferred to 5 are injected into the electron injection buffer 104 because the injection barrier is relaxed. The charge is easily injected into the LUMO level 113 of the first EL layer 103. The holes generated at 06 move to the second EL layer 107 .

[0031] Next, materials that can be used for the above-mentioned light-emitting element will be specifically described.

[0032] The anode 101 is preferably a metal having a large work function (specifically, 4.0 eV or more). , alloys, electrically conductive compounds, and mixtures thereof are preferably used. For example, indium oxide-tin oxide (ITO) ), indium oxide-tin oxide containing silicon or silicon oxide, indium oxide-tin oxide Zinc (IZO: Indium Zinc Oxide), Tungsten Oxide and Zinc Oxide Examples of the indium oxide include indium oxide containing

[0033] These conductive metal oxide films are usually formed by sputtering, but they can also be formed by the sol-gel method, etc. For example, indium oxide-zinc oxide (IZO) can be fabricated by applying the Sputtering using a target containing 1 to 20 wt% zinc oxide relative to indium In addition, the oxide film containing tungsten oxide and zinc oxide can be formed by the above-mentioned method. Indium is made by mixing 0.5 to 5 wt% tungsten oxide and 0.0 wt% zinc oxide with respect to indium oxide. It can be formed by sputtering using a target containing 1 to 1 wt% of do.

[0034] In addition, gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium ( Cr), Molybdenum (Mo), Iron (Fe), Cobalt (Co), Copper (Cu), Palladium (Pd), titanium (Ti), or nitrides of metallic materials (e.g., titanium nitride, etc.), molybdenum Dendrimer oxide, vanadium oxide, ruthenium oxide, tungsten oxide, manganese oxide It is also possible to form the anode 101 using a material such as titanium oxide. 4-Ethylenedioxythiophene) / Poly(styrenesulfonic acid) (PEDOT / PSS ), polyaniline / poly(styrenesulfonic acid) (PAni / PSS), and other conductive polymers However, a charge generating layer in contact with the anode 101 may be used as a part of the first EL layer 103. When creating a bare region, various conductive materials such as Al, Ag, etc. can be used regardless of the magnitude of the work function. It can be used for the anode 101.

[0035] The cathode 102 is preferably made of a material having a small work function (specifically, 3.8 eV or less). It is preferable to use metals, alloys, electrically conductive compounds, and mixtures thereof. Specific examples of such cathode materials include elements belonging to Groups 1 and 2 of the Periodic Table. The elements are alkali metals such as lithium (Li) and cesium (Cs), and magnesium. Alkaline earth metals such as magnesium (Mg), calcium (Ca), and strontium (Sr), and alloys containing these (MgAg, AlLi), europium (Eu), ytterbium ( Examples of rare earth metals include rare earth metals such as Yb) and alloys containing these. Films of alkaline earth metals and alloys containing these can be formed using vacuum deposition techniques. In addition, the alloy containing an alkali metal or an alkaline earth metal is formed by a sputtering method. It is also possible to form a film of silver paste by the inkjet method. is also possible.

[0036] Also, alkali metal compounds, alkaline earth metal compounds, or rare earth metal compounds (e.g. For example, lithium fluoride (LiF), lithium oxide (LiOx), and cesium fluoride (CsF ), calcium fluoride (CaF 2 ), erbium fluoride (ErF 3 ) and thin films of The cathode 102 can also be formed by laminating a metal film such as aluminum. However, a charge generating region in contact with the cathode 102 is provided as a part of the second EL layer 107. In this case, regardless of the magnitude of the work function, the material containing Al, Ag, ITO, silicon, or silicon oxide is A variety of conductive materials can be used for the cathode 102, such as indium oxide-tin oxide having a .

[0037] In the light-emitting element shown in this embodiment, at least one of the anode and the cathode The only requirement is that the material should have light-transmitting properties. The light-transmitting properties can be achieved by using a transparent electrode such as ITO or by using an electrode. This can be ensured by making the electrode film thin.

[0038] The first EL layer 103 and the second EL layer 107 are formed to include at least a light-emitting layer. It is sufficient that the first E The light-emitting layer included in the L layer 103 and the light-emitting layer included in the second EL layer 107 are different from each other. The first EL layer 103 and the second EL layer 107 may be independently In addition, the light-emitting layer may have a layered structure further including a hole-injecting layer. a substance with high hole transporting properties or high electron transporting properties; , a layer made of a bipolar substance (a substance having high electron and hole transporting properties), or the like. Specifically, a hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, These layers are appropriately combined from the anode side. Furthermore, a charge generating region is formed on the side of the first EL layer 103 that contacts the anode 101. A region can also be set up.

[0039] Specific examples of materials constituting each layer included in the above-mentioned EL layer are shown below.

[0040] The hole injection layer is a layer containing a substance with high hole injection properties. For example, molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide Other examples include phthalocyanine (abbreviation: H 2 PC ) and copper phthalocyanine (abbreviation: CuPc) and other phthalocyanine compounds, or poly( 3,4-Ethylenedioxythiophene) / Poly(styrenesulfonic acid) (PEDOT / P The hole injection layer can also be formed from a polymer such as SiO 2 .

[0041] The hole transport layer is a layer containing a substance having a high hole transporting property. , for example, 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl ( Abbreviation: NPB or α-NPD) and N,N'-bis(3-methylphenyl)-N,N'- Diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4 ',4''-Tris(carbazol-9-yl)triphenylamine (abbreviation: TCTA) , 4,4',4''-tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA), 4,4',4''-tris[N-(3-methylphenyl)-N-phenyl Amino]triphenylamine (abbreviation: MTDATA), 4,4'-bis[N-(spiro- 9,9'-Bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSP B) Aromatic amine compounds such as 3-[N-(9-phenylcarbazol-3-yl)- N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3,6- Bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenyl Nylcarbazole (abbreviation: PCzPCA2), 3-[N-(1-naphthyl)-N-(9- [Phenylcarbazol-3-yl]amino]-9-phenylcarbazole (abbreviation: PCz PCN1) and others. Others include 4,4'-di(N-carbazolyl)biphenyl (abbreviation CBP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation Name: TCPB), 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H Carbazole derivatives such as carbazole-carbazole (abbreviation: CzPA) can be used. The substances mentioned here are mainly -6 cm 2 A material that has a hole mobility of 1 / Vs or more. However, other materials may be used as long as they have a higher hole transporting property than an electron transporting property. The layer containing a substance having a high hole transporting property may be a single layer or a layer having two layers of the above substance. It may be a laminate of more than one layer.

[0042] In addition to these, poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyl triphenylamine) (abbreviation: PVTPA), poly[N-(4-{N'-[4-(4-diphenyl Phenylamino)phenyl]phenyl-N'-phenylamino}phenyl)methacrylate Poly[N,N'-bis(4-butylphenyl)-N,N' amide] (abbreviation: PTPDMA) -bis(phenyl)benzidine (abbreviation: Poly-TPD) and other polymer compounds are used to It can be used in the transport layer.

[0043] The light-emitting layer is a layer containing a light-emitting substance. The light-emitting substance is a fluorescent compound shown below. For example, N,N'-bis[4-(9H-carbazol-9-yl)phenyl]phenyl [phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviation: YGA2S) , 4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl) Triphenylamine (abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4 '-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAP PA), N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl ]-9H-Carbazole-3-amine (abbreviation: PCAPA), Perylene, 2,5,8,1 1-Tetra-tert-butylperylene (TBP), 4-(10-phenyl-9- Anthryl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenyl PCBAPA, N,N''-(2-tert-butylanthracene-9, 10-diyldi-4,1-phenylene)bis[N,N',N'-triphenyl-1,4- phenylenediamine] (abbreviation: DPABPA), N,9-diphenyl-N-[4-(9, 10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation Name: 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl ]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPP A) N,N,N',N',N'',N'',N'''',N'''-Octaphenyldibenzyl Chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), Phosphorus 30, N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H -Carbazole-3-amine (abbreviation: 2PCAPA), N-[9,10-bis(1,1' -Biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazol N-(9,10-diphenyl-2-anthracene) (aryl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPA PA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthryl] -N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPABPh A), 9,10-bis(1,1'-biphenyl-2-yl)-N-[4-(9H-carba 2YG ABPhA), N,N,9-triphenylanthracene-9-amine (abbreviation: DPhAP hA) Coumarin 545T, N,N'-diphenylquinacridone, (abbreviation: DPQd), 5,12-bis(1,1'-biphenyl-4-yl)-6,11-diphenyl ether Thracene (abbreviation: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]ethene {6-methyl-4H-pyran-4-ylidene)propanedinitrile (abbreviation: DCM 1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-beta 4H-pyran-4-ylidene)propane DCM2, N,N,N',N'-tetrakis(4-methylphenyl) p-mPhTD, 7,14-diphenyl -N,N,N',N'-Tetrakis(4-methylphenyl)acenaphtho[1,2-a]phenyl Phosphoranthene-3,10-diamine (abbreviation: p-mPhAFD), 2-{2-isopropyl 6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H ,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene 2-{2-tert-butyl-6-[2 -(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[b]pyridoxal) Zo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propane Dinitrile (abbreviation: DCJTB), 2-(2,6-bis{2-[4-(dimethylamino) Biphenyl]ethenyl}-4H-pyran-4-ylidene)propanedinitrile sDCM), 2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl -2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl) ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJT M) and others.

[0044] In addition, the following phosphorescent compounds can also be used as the light-emitting material. S[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]Iridium (I II) Tetrakis(1-pyrazolyl)borate (abbreviation: FIr6), bis[2-(4', 6'-Difluorophenyl)pyridinato-N,C 2’ ]Iridium(III) picolinar (abbreviation: FIrpic), bis[2-(3',5'-bistrifluoromethylphenyl ) Pyridinato-N,C 2’ ]Iridium(III) picolinate (abbreviation: Ir(CF 3 p py) 2 (pic)), bis[2-(4',6'-difluorophenyl)pyridinato-N ,C 2’ ]Iridium(III) acetylacetonate (abbreviation: FIracac), tri Bis(2-phenylpyridinato)iridium(III) (abbreviation: Ir(ppy) 3 ),bis (2-Phenylpyridinato)iridium(III) acetylacetonate (abbreviation: Ir( ppy) 2 (acac)), bis(benzo[h]quinolinato)iridium(III) acetonitrile Ir(bzq) 2 (acac)), bis(2,4-diphenyl -1,3-Oxazolato-N,C 2’ ) Iridium(III) acetylacetonate (abbreviation Name: Ir(dpo) 2 (acac)), bis[2-(4'-perfluorophenylphenyl Ir(p-PF-)pyridinato]iridium(III) acetylacetonate (abbreviation: Ir(p-PF- ph) 2 (acac)), bis(2-phenylbenzothiazolato-N,C 2’ ) Iridium Ir(III) acetylacetonate (abbreviation: Ir(bt) 2 (acac)), bis[2- (2'-Benzo[4,5-α]thienyl)pyridinato-N,C 3’]Iridium (III ) acetylacetonate (abbreviation: Ir(btp) 2 (acac)), bis(1-phenyl Isoquinolinato-N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: Ir (piq) 2 (acac)), (acetylacetonato)bis[2,3-bis(4-fluoro (Fdpq)(phenyl)quinoxalinato)iridium(III) 2 (ac ac)), (acetylacetonato)bis(2,3,5-triphenylpyrazinate)iridide Ir(tppr) 2 (acac)), 2,3,7,8,12,1 3,17,18-Octaethyl-21H,23H-porphyrin platinum(II) (abbreviation: P tOEP), tris(acetylacetonato)(monophenanthroline)terbium(II I) (Abbreviation: Tb(acac) 3 (Phen)), Tris(1,3-diphenyl-1,3 -propanedionato)(monophenanthroline)europium(III)(abbreviation:Eu( DBM) 3 (Phen)), tris[1-(2-thenoyl)-3,3,3-trifluoro Acetonato](monophenanthroline)europium(III) (abbreviation: Eu(TTA) 3 (Phen)).

[0045] It is preferable that these light-emitting substances are dispersed in a host material. For example, NPB (abbreviation), TPD (abbreviation), TCTA (abbreviation), TDATA ( Aromatic amine compounds such as PCzP, MTDATA, and BSPB. CA1 (abbreviation), PCzPCA2 (abbreviation), PCzPCN1 (abbreviation), CBP (abbreviation), TCPB (abbreviation), CzPA (abbreviation), 4-(1-naphthyl)-4'-(9-phenyl- 9H-Carbazol-3-yl)-triphenylamine (abbreviation: PCBANB) Rubazol derivatives, PVK (abbreviation), PVTPA (abbreviation), PTPDMA (abbreviation), Po Materials with high hole transport properties, including polymer compounds such as ly-TPD (abbreviation), and tris(8- Quinolinolato)aluminum (abbreviation: Alq), tris(4-methyl-8-quinolinolato) ) Aluminum (abbreviation: Almq 3 ), bis(10-hydroxybenzo[h]quinolinato ) Beryllium (abbreviation: BeBq 2 ), bis(2-methyl-8-quinolinolato)(4-phenyl quinoline or benzoquinoline skeletons, such as (BAlq) Metal complexes with phosphorus skeletons, bis[2-(2-hydroxyphenyl)benzoxazolato ]Zinc (Abbreviation: Zn(BOX) 2 ), bis[2-(2-hydroxyphenyl)benzothiazolidinyl Zorato]zinc (abbreviation: Zn(BTZ) 2 ) and other oxazole and thiazole ligands Metal complexes with 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1 ,3,4-Oxadiazole (abbreviation: PBD), 1,3-bis[5-(p-tert-butyl) OXD-1,3,4-oxadiazol-2-yl]benzene 7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl ]Carbazole (abbreviation: CO11), 3-(4-biphenylyl)-4-phenyl-5-( 4-tert-Butylphenyl)-1,2,4-triazole (abbreviation: TAZ), Basof Phenophenanthroline (BPhen), Bathocuproine (BCP), Poly[(9 ,9-Dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl) ] (abbreviation: PF-Py), poly[(9,9-dioctylfluorene-2,7-diyl)- co-(2,2'-bipyridine-6,6'-diyl)] (abbreviation: PF-BPy) A substance having a high electron transport property can be used.

[0046] The electron transport layer is a layer containing a substance having a high electron transporting property. For example, Alq (abbreviation), Almq 3 (Abbreviation), BeBq 2 (abbreviation), BAlq (abbreviation Metal complexes having a quinoline skeleton or a benzoquinoline skeleton, such as In addition, Zn(BOX) 2 (abbreviation), Zn(BTZ) 2 (abbreviation) etc. Metal complexes having azole or thiazole ligands can also be used. In addition to the group complexes, PBD (abbreviation), OXD-7 (abbreviation), CO11 (abbreviation), TAZ ( Other names such as BPhen (abbreviation), BCP (abbreviation), etc. may also be used. The substances that were found were mainly 10 -6 cm 2 / Vs or higher. Other substances may be used as long as they have a higher electron transporting property than the above. The transport layer may be a single layer or may be a laminate of two or more layers of the above materials. Good too.

[0047] In addition, we have also developed polymer compounds such as PF-Py (abbreviation) and PF-BPy (abbreviation). It can be used in the transport layer.

[0048] The electron injection layer is a layer containing a substance with high electron injection properties. , lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF 2 ) and other alkali metals, alkaline earth metals, or compounds thereof. Contains alkali metals, alkaline earth metals or their compounds in substances with electron transport properties For example, magnesium (Mg) may be contained in Alq. By adopting such a structure, the efficiency of electron injection from the cathode 102 can be further increased. This can be done.

[0049] When a charge generating region is provided in the first EL layer 103 or the second EL layer 107, The region is a region containing a substance with high hole transporting properties and a substance with acceptor properties. The region is not limited to the case where a substance with high hole transport properties and a substance with high hole acceptor properties are contained in the same film. Even if a layer containing a substance with high hole transport properties and a layer containing a substance with high hole transport properties are stacked, However, in the case of a laminated structure provided on the anode side, the layer containing the acceptor material is preferably placed on the anode side. In the case of a laminated structure provided on the cathode side, a material with high hole transport properties is used. The layer containing the metal oxide is in contact with the cathode 102 .

[0050] By forming a charge generating region in the first EL layer 103 or the second EL layer 107, Forming the anode 101 or cathode 102 without considering the work function of the material forming the electrode can be done.

[0051] Acceptor substances used in the charge generation region include transition metal oxides and elements in the periodic table. Examples of the oxides of metals belonging to Groups 4 to 8 in the present invention include oxides of metals belonging to Groups 4 to 8 in the present invention. Molybdenum oxide is particularly preferred. Molybdenum oxide has the characteristic of being low in hygroscopicity. do.

[0052] In addition, examples of the material having a high hole transporting property used in the charge generating region include aromatic amine compounds, cations, and cations. Rubazole derivatives, aromatic hydrocarbons, polymer compounds (oligomers, dendrimers, polymers Various organic compounds such as 10 -6 cm 2 / V It is preferable that the material has a hole mobility of s or more. However, the material has a higher hole transporting property than the electron transporting property. Any other substance having a high resistance may be used.

[0053] By laminating these layers in an appropriate combination, the first EL layer 103 or The second EL layer 107 can be formed. Also, the first EL layer 103 or the second EL layer The L layer 107 can be formed by various methods (e.g., a dry method or a wet method) depending on the material used. For example, a vacuum deposition method, an ink jet method, or a spin deposition method may be selected as appropriate. A coating method or the like can be used. Also, each layer may be formed by using a different method.

[0054] In addition, between the first EL layer 103 and the second EL layer 107, an electrode is provided in the order from the anode 101 side. A charge injection buffer 104, an electron relay layer 105 and a charge generation region 106 are provided. Formed in contact with the second EL layer 107 is a charge generation region 106. The electronic relay layer 105 is formed adjacent to the region 106. Formed between and adjacent to the first EL layer 103 is an electron injecting buffer 104 .

[0055] The charge generation region 106 is a region containing a substance with high hole transporting properties and a substance with acceptor properties. The charge generating region 106 is the first EL layer 103 or the second EL layer 104 described above. The charge generating region can be formed in a portion of the 07 using the same material and with the same structure. Therefore, the charge generation region 106 can be formed by using a material having a high hole transporting property in the same film. In addition to the case where a layer containing a material with high hole transport properties and an acceptor material is used, It is also possible to have a laminated structure with a layer containing a scepter-like substance. In that case, a layer containing a substance with a high hole transporting property is in contact with the second EL layer 107 .

[0056] In the charge generation region 106, the mass ratio of the material having a high hole transporting property to the material having a high hole transporting property is 0.1 It is preferable to add the acceptor substance at a ratio of 0.1 to 4.0.

[0057] The electron relay layer 105 is formed by the acceptor material withdrawn from the charge generating region 106. The electron-relay layer 105 is a layer that can quickly receive electrons. The layer contains a material with high transport properties, and the LUMO level of the layer is The level between the acceptor level of the acceptor and the LUMO level of the first EL layer 103 It is preferable to form the substrate using a material that occupies a potential of about -5.0 eV or less. It is preferable to use a material having a LUMO level of about -5.0 eV or higher, about -3.0 eV or higher. It is more preferable to use a material having a LUMO level of 100 eV or less for the electron relay layer 105. Examples of the substances used include perylene derivatives and nitrogen-containing condensed aromatic compounds. In addition, since the nitrogen-containing condensed aromatic compound is a stable compound, it is not suitable for use in the electron relay layer 105. Furthermore, among nitrogen-containing condensed aromatic compounds, those having a cyano group or a fluoro group are preferable. By using a compound having an electron-withdrawing group such as This is preferable because it makes it easier to receive the

[0058] Specific examples of perylene derivatives include 3,4,9,10-perylenetetracarboxylic acid diamines. Water (abbreviation: PTCDA), 3,4,9,10-perylenetetracarboxylic acid bisbe Benzoimidazole (abbreviation: PTCBI), N,N'-dioctyl-3,4,9,10-phenyl Rylenetetracarboxylic diimide (abbreviation: PTCDI-CH), N,N'-dihexyl -3,4,9,10-perylenetetracarboxylic diimide (abbreviation: HexPTC) Can be obtained.

[0059] Specific examples of nitrogen-containing condensed aromatic compounds include pyrazino[2,3-f][1,10] Phenanthroline-2,3-dicarbonitrile (PPDN), 2,3,6,7,1 0,11-Hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation :HAT(CN) 6 ), 2,3-diphenylpyrido[2,3-b]pyrazine (abbreviation: 2P YPR) 2,3-bis(4-fluorophenyl)pyrido[2,3-b]pyrazine (abbreviation: F2PYPR) and others. Other examples include perfluoropentacene, 7,7,8,8 ,-Tetracyanoquinodimethane (abbreviation: TCNQ), 1,4,5,8,-naphthalene NTCDA, copper hexadecafluorophthalocyanine Name: F 16CuPc), N,N'-bis(2,2,3,3,4,4,5,5,6,6,7 ,7,8,8,8,Pentadecafluorooctyl-1,4,5,8-naphthalenetetracarbonate Carboxylic acid diimide (abbreviation: NTCDI-C8F), 3',4'-dibutyl-5,5''- Bis(dicyanomethylene)-5,5''-dihydro-2,2':5',2''-terthio phene) (abbreviation: DCMT), methanofullerenes (e.g., [6,6]-phenyl C 61 Dairy For the electron relay layer 105, poly(ethylene glycol) methyl ester (PCBM) or the like can be used.

[0060] The electron injection buffer 104 transfers the electrons received by the electron relay layer 105 to the first EL layer 1 By providing the electron injection buffer 104, Since the injection barrier between the charge generating region 106 and the first EL layer 103 can be reduced, Therefore, electrons generated in the charge generating region 106 can be easily injected into the first EL layer 103. do.

[0061] The electron injection buffer 104 may include alkali metals, alkaline earth metals, rare earth metals, and and their compounds (alkali metal compounds (oxides such as lithium oxide, halides, carbonates, etc.) (including carbonates such as lithium and cesium carbonate), alkaline earth metal compounds (oxides, halides, etc.) compounds of rare earth metals (including oxides, halides, carbonates) It is possible to use a substance having a high electron injection property such as SiO 2 .

[0062] In addition, the electron injection buffer 104 is formed by containing a substance having high electron transport properties and a donor substance. In the case where the compound is formed, the mass ratio of the compound to the substance having high electron transport properties is 0.001 or more and 0.1 or less. It is preferable to add the donor substance in a ratio of 1:1. Alkali metals, alkaline earth metals, rare earth metals, and their compounds (alkali metal compounds ( Includes oxides such as lithium oxide, halides, and carbonates such as lithium carbonate and cesium carbonate. ), alkaline earth metal compounds (including oxides, halides, and carbonates), or rare earth metals In addition to compounds of the group (including oxides, halides, and carbonates), tetrathianaphthacene (abbreviated Organic compounds such as TTN, nickelocene, and decamethylnickelocene can also be used. As the substance having a high electron transporting property, the above-described substance that is contained in a part of the first EL layer 103 can be used. The insulating layer can be formed using the same materials as those of the electron transport layer.

[0063] The light-emitting element shown in this embodiment is manufactured by combining the above-mentioned materials. From this light-emitting element, light is emitted from the above-mentioned light-emitting material, but the light-emitting layer By changing the type of luminescent material used, various luminescent colors can be obtained. By using multiple light-emitting materials with different luminescent colors, a broad spectrum can be achieved. It is also possible to obtain light emission of 1000 nm or white light emission.

[0064] In this embodiment, a light emitting element having two EL layers is described. The number of EL layers is not limited to two, but may be more than two, for example, three. When a light-emitting element has n (n is a natural number of 2 or more) EL layers, m (m is a natural number, 1≦m Between the (n-1)th EL layer and the (m+1)th EL layer, an electron injection buffer is placed in the order from the anode side. By stacking the fur, electron relay layer, and charge generation region, the driving voltage of the light-emitting element is increased. can be suppressed.

[0065] In addition, the light-emitting element shown in this embodiment mode can be formed over various substrates. Examples of the material that can be used include glass, plastic, metal plate, and metal foil. When light emitted from the element is extracted from the substrate side, a light-transmitting substrate may be used. The plate may be any other plate as long as it functions as a support in the manufacturing process of the light-emitting device. So that's fine.

[0066] In addition, in the element structure of the light-emitting element shown in this embodiment mode, both electrodes are formed in a lattice shape over one substrate. In addition, a passive matrix type light-emitting device can be fabricated. The device has a light emitting element electrically connected to a thin film transistor (TFT) or the like that functions as a light emitting element. In this way, it is possible to manufacture an active matrix type light emitting device in which the driving of the light emitting element is controlled. The structure of the TFT is not particularly limited. It may be a staggered TFT or an inverted staggered TFT. The driving circuit composed of TFTs may be either N-type or P-type. The TFT may be of either N-type or P-type. In addition, the crystallinity of the semiconductor film used in the TFT may be There is no particular limitation on the type of the semiconductor film. An amorphous semiconductor film may be used, or a crystalline semiconductor film may be used. In addition, a single crystal semiconductor film or a microcrystalline semiconductor (microcrystal semiconductor) may be used. Furthermore, an oxide semiconductor, for example, an oxide semiconductor containing indium, gallium, and zinc, may be used. A semiconductor material can be used.

[0067] In addition, the light-emitting element shown in this embodiment can be manufactured by a dry process (for example, Vacuum deposition method, sputtering method, etc.), wet process (e.g., inkjet method, spin The insulating layer 12 can be formed by using various methods, regardless of whether the insulating layer 12 is a laminated layer, a coating method, a painting method, or the like.

[0068] By using the element structure shown in this embodiment, the driving voltage of the charge generating region 106 Since it is possible to make the film less susceptible to the influence of the film thickness, the increase in the driving voltage of the light-emitting element can be prevented. It is possible to suppress the interference and improve the color purity by optical adjustment.

[0069] In addition, by using the element structure shown in this embodiment mode, the charge generation region 106 and the electron injection Since the electron relay layer 105 is sandwiched between the buffer 104, the charge generation region The acceptor contained in 106 and the high electron injection property contained in the electron injection buffer 104 The structure is such that the molecules are unlikely to interact with each other or with donor substances, and the functions of each are unlikely to be inhibited. Therefore, the light emitting element can be driven at a low voltage.

[0070] Note that the structure described in this embodiment mode may be used in appropriate combination with structures described in other embodiment modes. It is assumed that it is possible to

[0071] (Embodiment 2) In the second embodiment, an example of a light emitting element included in the basic configuration described in the first embodiment will be described. 2A and 2B, the light-emitting element shown in Embodiment 1 will be described. Among these, the electron injection buffer 104 is preferably made of an alkali metal, an alkaline earth metal, a rare earth metal, or A case where the layer is a single layer of the compound is described below.

[0072] The light-emitting element shown in this embodiment has a pair of electrodes (anode 101 and cathode 102) as shown in FIG. A first EL layer 103 and a second EL layer 107 each including a light-emitting region are sandwiched between the electrodes 102. Between the first EL layer 103 and the second EL layer 107, an electron injection buffer is provided from the anode 101 side. The photoresist layer 104, the electron relay layer 105, and the charge generating region 106 are laminated in this order. do.

[0073] The anode 101, the cathode 102, the first EL layer 103, and the second EL layer in the second embodiment The charge generating region 107, the charge generating region 106, and the electron relay layer 105 are the same as those described in the first embodiment. The same materials as those used can be used.

[0074] In this embodiment, the material used for the electron injection buffer 104 is lithium ( Alkaline metals such as Li and cesium (Cs), magnesium (Mg) and calcium (Ca ) and alkaline earth metals such as strontium (Sr), europium (Eu) and ytterbi Rare earth metals such as yttrium (Yb), alkali metal compounds (oxides such as lithium oxide, halogens cations, carbonates such as lithium carbonate and cesium carbonate), alkaline earth metal compounds (oxides compounds of rare earth metals (including oxides, halides, carbonates) Examples of suitable materials include those having high electron injection properties, such as tetrahydrofuran and carbonates.

[0075] The light-emitting element shown in this embodiment mode uses the above-mentioned metal or A single layer of the compound is provided, and the film thickness is very thin to avoid an increase in the driving voltage. In this embodiment, the first The EL layer 103 is preferably provided with an electron transport layer 108 in contact with the electron injection buffer 104. Preferably, the electron injection buffer 104 is a part of the electron relay layer 105 and the EL layer 103. It exists almost at the interface with the electron transport layer 108. However, after the electron transport layer 108 is formed, When the electron injection buffer 104 is formed on the transport layer 108, the electron injection buffer 1 A part of the material forming 04 may also be present in the electron transport layer 108, which is a part of the EL layer 103. do.

[0076] FIG. 2B shows a band diagram of the element structure of FIG. 2A. An electron injection buffer 104 is provided at the interface between the electron relay layer 105 and the first EL layer 103. This reduces the injection barrier between the charge generating region 106 and the first EL layer 103. Therefore, electrons generated in the charge generating region 106 can be easily injected into the first EL layer 103. In addition, the holes generated in the charge generating region 106 can be transported to the second EL layer 10. Go to 7.

[0077] By adopting the structure of the electron injection buffer shown in this embodiment, Compared to the electron injection buffer (formed by adding a donor substance to a substance with high electron transport properties), In this embodiment, the driving voltage of the light emitting element can be reduced. The material having high electron injection properties in the injection buffer 104 is an alkali metal compound (acid (including oxides such as lithium chloride, halides, and carbonates such as lithium carbonate and cesium carbonate) , alkaline earth metal compounds (including oxides, halides, and carbonates), or rare earth metals It is preferable to use compounds such as oxides, halides, and carbonates. Materials with high electron injection properties are stable in air, making them suitable for mass production with good productivity. .

[0078] Note that the structure described in this embodiment mode may be used in appropriate combination with structures described in other embodiment modes. It is assumed that it is possible to

[0079] (Embodiment 3) In the third embodiment, an example of a light emitting element included in the basic configuration described in the first embodiment will be described. 3A and 3B will be used to describe the structure of the light-emitting element shown in Embodiment 1. The electron injection buffer 104 is formed by containing a material having high electron transport properties and a donor material. We will explain what happens when this happens.

[0080] The light-emitting element shown in this embodiment has a pair of electrodes (anode 101 and cathode 102) as shown in FIG. A first EL layer 103 and a second EL layer 107 each including a light-emitting region are sandwiched between the electrodes 102. Between the first EL layer 103 and the second EL layer 107, an electron injection buffer is provided from the anode 101 side. The photoresist layer 104, the electron relay layer 105, and the charge generating region 106 are laminated in this order. The electron injection buffer 104 contains a substance with high electron transport properties and a donor substance. is formed.

[0081] In this embodiment, the mass ratio of the substance having a high electron transporting property is 0.001 or more and It is preferable to add a donor substance at a ratio of 0.1 or less. This will result in a good electron film quality. The injection buffer 104 is obtained, and the electron injection buffer 104 has good reactivity. This can be done.

[0082] Anode 101, cathode 102, EL layer 103, and charge generation region 106 in the third embodiment The electron relay layer 105 is made of the same material as that described in the first embodiment. This can be done.

[0083] In this embodiment, the material having a high electron transporting property used for the electron injection buffer 104 is Examples of the aluminum compounds include tris(8-quinolinolato)aluminum (Alq), tris(4 -Methyl-8-quinolinolato)aluminum (abbreviation: Almq 3 ), bis(10-hydro Benzo[h]quinolinato) beryllium (abbreviation: BeBq 2 ), bis(2-methyl-8 -quinolinolato)(4-phenylphenolato)aluminum (abbreviation: BAlq), Metal complexes having a quinoline or benzoquinoline skeleton can be used. In addition, bis[2-(2-hydroxyphenyl)benzoxazolato]zinc (abbreviation: Zn( BOX) 2 ), bis[2-(2-hydroxyphenyl)benzothiazolato]zinc (abbreviation: Zn(BTZ) 2 ) and other metal complexes with oxazole and thiazole ligands. In addition to metal complexes, 2-(4-biphenylyl)-5-(4 -tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD) and ,3-Bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazole- 2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-o 3-(4-(2-oxadiazol-2-yl)phenyl)carbazole (abbreviation: CO11), Phenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-t Riazol (abbreviation: TAZ), Bathophenanthroline (abbreviation: BPhen), Bathocup BCP (abbreviation: BCP) can also be used. -6 cm 2 It is a material that has an electron mobility of 0.1V or more.

[0084] In addition, poly[(9,9-dihexylfluorene-2,7-diyl)-co-( pyridine-3,5-diyl)] (abbreviation: PF-Py), poly[(9,9-dioctylfulv oren-2,7-diyl)-co-(2,2'-bipyridine-6,6'-diyl)](abbreviation Polymer compounds such as PF-BPy can be used.

[0085] In this embodiment, the donor material used in the electron injection buffer 104 is The term refers to alkali metals, alkaline earth metals, rare earth metals, and their compounds (alkali metals). Metal compounds (oxides such as lithium oxide, halides, carbon dioxide such as lithium carbonate and cesium carbonate) alkaline earth metal compounds (including oxides, halides, and carbonates); can be used with compounds of rare earth metals (including oxides, halides, carbonates, etc.) In addition, tetrathianaphthacene (abbreviation: TTN), nickelosene, decamethyl nickelosene Organic compounds such as benzene and the like can also be used.

[0086] In this embodiment, the first EL layer 103 is in contact with an electron injection buffer 104. When the electron transport layer 108 is formed, the electron injection barrier A material with high electron transport properties used in the buffer 104 and an electron transport layer that is a part of the EL layer 103 The material with high electron transporting properties used for 108 may be the same or different.

[0087] The light-emitting element shown in this embodiment has an EL layer 103 and an electron relay layer 104 as shown in FIG. 105, an electron injection buffer 104 containing a substance with high electron transport properties and a donor substance between the The band diagram for this element structure is shown in Figure 3(B).

[0088] That is, the electron injection buffer 104 is formed, and the electron relay layer 105 and Since the injection barrier between the EL layer 103 and the charge generation region 106 can be reduced, The electrons generated in the charge generating region 106 can be easily injected into the EL layer 103. The holes generated in the second EL layer 107 move to the second EL layer 107 .

[0089] Note that the structure described in this embodiment mode may be used in appropriate combination with structures described in other embodiment modes. It is assumed that it is possible to

[0090] (Embodiment 4) In the fourth embodiment, as an example of a light-emitting element included in the basic configuration described in the first embodiment, The configuration of the charge generating region 106 will now be described with reference to FIGS.

[0091] The element structure shown in FIG. 4(A) and (B) is a light-emitting element between a pair of electrodes (anode 101 and cathode 102). A first EL layer 103 and a second EL layer 107 are sandwiched, the first EL layer 1 Between the anode 101 and the second EL layer 107, an electron injection buffer 104 and an electron The relay layer 105 and the charge generating region 106 are laminated in this order. In B), an anode 101, a cathode 102, a first EL layer 103, an electron injection buffer 10 4, the electron relay layer 105, and the second EL layer 107 are the same as those described in the first embodiment. Similar materials and structures may be used.

[0092] In the light-emitting element shown in FIGS. 4A and 4B, the charge generation region 106 has a high hole-transporting property. The charge generation region 106 is a region containing a hole transport material and an acceptor material. When an acceptor material removes an electron from a highly conductive material, holes and electrons are generated. do.

[0093] The charge generation region 106 shown in FIG. 4A is a region in which a substance with high hole transport properties and an acceptor are contained in the same film. In this case, the mass ratio of the material having a high hole transporting property to the material having a high hole transporting property is By adding an acceptor substance at a ratio of 0.1 to 4.0, charge generation This is preferable because it facilitates generation of carriers in the region 106 .

[0094] In FIG. 4(A), an acceptor substance is doped into a substance with high hole transport properties. Therefore, even if the charge generating region 106 is made thick, an increase in the driving voltage can be suppressed. Therefore, the increase in the driving voltage of the light-emitting element can be suppressed, and the color purity can be improved by optical adjustment. In addition, by making the charge generating region 106 thicker, the light emitting element can be shortened. Interference can be prevented.

[0095] On the other hand, the charge generation region 106 shown in FIG. 4B is a layer 106 containing a substance with a high hole transporting property. The layer 106a and the layer 106b containing an acceptor substance are stacked. In the charge generating region 106 of the light emitting element, a substance having a high hole transporting property and a substance having an acceptor property are The electron transfer complex formed by the contact between the two and electron transfer occurs has high hole transport properties. The layer 106a containing the acceptor material and the layer 106b containing the acceptor material are only formed at the interface between the layer 106a containing the acceptor material and the layer 106b containing the acceptor material. Therefore, in the light emitting element shown in FIG. 4B, when the thickness of the charge generating region 106 is increased, Even in this case, it is preferable since a visible light absorption band is unlikely to be formed.

[0096] In addition, the light-emitting element shown in FIG. 4B may be combined with the structure described in the second embodiment to produce an electronic The injection buffer 104 is an alkali metal, an alkaline earth metal, a rare earth metal, or a combination thereof. By forming the layer between the first EL layer 103 and the second EL layer 107 as a single layer of the material, The electron injection buffer 104, the electron relay layer 105, and the charge generation region 106 are doped with The total thickness of these layers can be reduced to less than 5 nm. It can be made into a film.

[0097] The material having a high hole transporting property used for forming the charge generating region 106 is an aromatic amine. Compounds, carbazole derivatives, aromatic hydrocarbons, polymer compounds (oligomers, dendrimers, etc.) Various organic compounds such as 10 - 6 cm 2 It is preferable that the material has a hole mobility of 1 / Vs or more. Any other substance may be used as long as it has a high hole transporting property.

[0098] Specific examples of aromatic amine compounds include 4,4'-bis[N-(1-naphthyl)-N- phenylamino]biphenyl (abbreviation: NPB or α-NPD) and N,N'-bis(3- Methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diazo 4,4',4''-Tris(carbazol-9-yl)triphenylphosphine(TPD) N,N-diphenylamine (TCTA), 4,4',4''-tris(N,N-diphenylamino) ) Triphenylamine (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: DTDPPA), 4,4'-bis[N-(4-diphenylaminophenyl)-N -phenylamino]biphenyl (abbreviation: DPAB), 4,4'-bis[N-(3-methyl phenyl)-N-phenylamino]biphenyl (abbreviation: DNTPD), 1,3,5-tri D-[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: D PA3B) etc.

[0099] Specific examples of carbazole derivatives include 3-[N-(9-phenylcarbazole-3- yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-Bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]- 9-Phenylcarbazole (abbreviation: PCzPCA2), 3-[N-(1-naphthyl)-N -(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole (abbreviation PCzPCN1) and others. Nyl (abbreviation: CBP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzoyl Zene (abbreviation: TCPB), 9-[4-(10-phenyl-9-anthracenyl)phenyl ]-9H-carbazole (abbreviation: CzPA), 1,4-bis[4-(N-carbazolyl) phenyl]-2,3,5,6-tetraphenylbenzene and the like.

[0100] Specific examples of aromatic hydrocarbons include 2-tert-butyl-9,10-di(2-naphthyl) 2-tert-butyl-9,10-di(1 -naphthyl)anthracene, 9,10-bis(3,5-diphenylphenyl)anthracene DPPA, 2-tert-butyl-9,10-bis(4-phenylphenyl) )anthracene (abbreviation: t-BuDBA), 9,10-di(2-naphthyl)anthracene (Abbreviation: DNA), 9,10-diphenylanthracene (Abbreviation: DPAnth), 2-t ert-Butylanthracene (abbreviation: t-BuAnth), 9,10-bis(4-methyl -1-naphthyl)anthracene (abbreviation: DMNA), 9,10-bis[2-(1-naphthyl)anthracene 9,10-bis[2-(1-naphthalene)phenyl]-2-tert-butylanthracene, 2,3,6,7-tetramethyl-9,10-di(1-nathyl)phenyl]anthracene 2,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene Anthracene, 9,9'-bianthryl, 10,10'-diphenyl-9,9'-bianthryl tolyl, 10,10'-bis(2-phenylphenyl)-9,9'-bianthryl, 10 ,10'-Bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9'-bis Anthracene, anthracene, tetracene, rubrene, perylene, 2,5,8,11-tetra (tert-butyl)perylene, etc. In addition, pentacene, coronene, etc. can also be used. Thus, 1×10 -6 cm 2 / Vs or more It is more preferable to use an aromatic hydrocarbon having 14 to 42 carbon atoms.

[0101] The aromatic hydrocarbon may have a vinyl skeleton. Examples of aromatic hydrocarbons include 4,4'-bis(2,2-diphenylvinyl)biphenyl. (abbreviation: DPVBi), 9,10-bis[4-(2,2-diphenylvinyl)phenyl] anthracene (abbreviation: DPVPA), etc.

[0102] In addition, poly(N-vinylcarbazole) (abbreviation: PVK) and poly(4-vinyltrifluoroethylene) Polymer compounds such as polyphenylamine (PVTPA) can also be used.

[0103] The acceptor material used to form the charge generating region 106 is 7,7,8,8-tetraphenylene. tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F 4 -TCNQ), Chloranil and the like can be used. Transition metal oxides can also be used. Examples of the oxides include those of metals belonging to groups 4 to 8 of the periodic table. In particular, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, and oxide Tungsten oxide, manganese oxide, and rhenium oxide are preferred because they have high electron accepting properties.

[0104] Note that the structure described in this embodiment mode may be used in appropriate combination with structures described in other embodiment modes. It is assumed that it is possible to

[0105] (Embodiment 5) In the fifth embodiment, another example of the light-emitting element included in the basic configuration described in the first embodiment is This will be described with reference to FIG.

[0106] The light-emitting element shown in this embodiment mode has a pair of electrodes (anode 101, A first EL layer 103 and a second EL layer 107 including a light-emitting region are sandwiched between the cathode 102. Between the first EL layer 103 and the second EL layer 107, an electron injection barrier is provided from the anode 101 side. The buffer 104, the electron relay layer 105, and the charge generation region 106 are laminated in this order. Yes.

[0107] In this embodiment, the anode 101, the cathode 102, the electron injection buffer 104, the electron relay The charge generation layer 105 and the charge generation region 106 are made of the same materials as those described in the first embodiment. It can be used.

[0108] In this embodiment, the first EL layer 103 has a peak in the blue to blue-green wavelength region. The first light-emitting layer 103-1 has an emission spectrum with a peak in the yellow to orange wavelength region. The second EL layer 103-2 has an emission spectrum having the above structure. 07 is a third light-emitting layer 1 having an emission spectrum with a peak in the blue-green to green wavelength region. 07-1, and a fourth light-emitting layer having an emission spectrum having a peak in the orange to red wavelength region. The first light-emitting layer 103-1 and the second light-emitting layer 103-2 are reversed. The third light-emitting layer 107-1 and the fourth light-emitting layer 107-2 may be stacked in the reverse order. The order of lamination may also be used.

[0109] For such a light emitting device, the anode 101 side is biased positively and the cathode 102 side is biased negatively. When a voltage is applied, holes are injected from the anode 101 and electrons are generated in the charge generation region 106. The electrons injected through the relay layer 105 and the electron injection buffer 104 are incident on the first light-emitting layer 102. The first light emission 330 is obtained by recombining in the first light-emitting layer 103-1 or the second light-emitting layer 103-2. Furthermore, the electrons injected from the cathode 102 and the holes generated in the charge generating region 106 are The electrons recombine in the light-emitting layer 107-1 or the fourth light-emitting layer 107-2 to produce a second emission 340. Obtained.

[0110] First light emission 330 is emitted from both first light-emitting layer 103-1 and second light-emitting layer 103-2. As shown in FIG. 24(B), the wavelength range is blue to blue-green. The emission spectrum has peaks in both the yellow and orange wavelength regions. The EL layer 103 emits white or nearly white light of a two-wavelength type. The second light emission 340 is emitted from both the third light-emitting layer 107-1 and the fourth light-emitting layer 107-2. Since the light emitted from these two sources is combined, as shown in Figure 24(B), the wavelength range is from blue-green to green. and an emission spectrum having peaks in the orange to red wavelength region. The second EL layer 107 is a two-wavelength type white or near-white EL layer different from the first EL layer 103. It emits light of various colors.

[0111] Therefore, the light emitting element in this embodiment has a first emission 330 and a second emission 34. The result of overlapping 0s is the blue to blue-green wavelength range, the blue-green to green wavelength range, and the yellow to orange wavelength range. The resulting light emission covers the wavelength ranges from 1000 nm to 1500 nm and from 1000 nm to 2000 nm, and from 1000 nm to 2000 nm.

[0112] In this embodiment, for example, the first light-emitting layer 103-1 (emitting light in the blue to blue-green wavelength range) The luminance of the luminescence of the luminescence element (which shows an emission spectrum with a peak) deteriorates with time or changes with the current density. Even if the change occurs, the contribution of the first light-emitting layer 103-1 to the entire spectrum is about 1 / 4. Therefore, the deviation in chromaticity is relatively small.

[0113] In the above description, the first EL layer 103 emits light in the wavelength range of blue to blue-green and yellow to orange. The second EL layer 107 exhibits a spectrum having peaks in both wavelength regions of blue-green and red-green. In the case of a spectrum having peaks in both the green wavelength region and the orange to red wavelength region, However, the relationship may be reversed. A spectrum with peaks in both the blue to blue-green wavelength region and the yellow to orange wavelength region. The first EL layer 103 has a wavelength range of blue-green to green and a wavelength range of orange to red. The first EL layer 103 may have a spectrum having peaks on both sides. The first and second EL layers 107 may each have a laminated structure in which a layer other than the light-emitting layer is formed. stomach.

[0114] Next, a light-emitting organic compound is used in the EL layer of the light-emitting element shown in this embodiment mode. However, the materials that can be applied to the light-emitting element shown in this embodiment mode are as follows: However, the present invention is not limited to the above.

[0115] Blue to blue-green emission is achieved, for example, by perylene, 2,5,8,11-tetra-t-butyl perylene, Using rylene (abbreviation: TBP), 9,10-diphenylanthracene, etc. as guest materials The compound can be obtained by dispersing it in a suitable host material. Styrylarylene derivatives such as 2-diphenylvinyl)biphenyl (abbreviation: DPVBi) The body, 9,10-di-2-naphthylanthracene (abbreviation: DNA), 9,10-bis(2 -naphthyl)-2-t-butylanthracene (abbreviation: t-BuDNA) It can also be obtained from poly(9,9-dioctylfluorene) and other poly(9,9-dioctylfluorene) derivatives. As a blue-emitting guest material, a styrylamine derivative is preferable. Preferably, N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N' -Diphenylstilbene-4,4'-diamine (abbreviation: YGA2S) and N,N'-diphenyl phenyl-N,N'-bis(9-phenyl-9H-carbazol-3-yl)stilbene 4,4'-diamine (abbreviation: PCA2S) and others. In particular, YGA2S has a The host material has a peak at about 1 nm, which is preferable. The compound is preferably 9,10-bis(2-naphthyl)-2-t-butylanthracene (abbreviation: t-BuDNA) and 9-[4-(10-phenyl-9-anthryl)phenyl]-9H CzPA is particularly suitable because it is electrochemically stable. This is preferable because

[0116] Blue-green to green light is emitted from, for example, coumarin dyes such as coumarin 30 and coumarin 6, Bis[2-(2,4-difluorophenyl)pyridinato]picolinatoiridium (abbreviation: FIrpic), bis(2-phenylpyridinato)acetylacetonatoiridium (abbreviation :Ir(ppy) 2 (acac)) as a guest material and dissociated into an appropriate host material. It can be obtained by dispersing the above-mentioned perylene or TBP at a high concentration of 5 wt% or more. It can also be obtained by dispersing it in a suitable host material. Z) 2 , bis(2-methyl-8-quinolinolato)chlorogallium (Ga(mq) 2 Cl) It can also be obtained from metal complexes such as poly(p-phenylene vinylene). As a guest material for the blue-green to green light-emitting layer, anthracene A 9,10-bis{4-[N -(4-diphenylamino)phenyl-N-phenyl]aminophenyl}-2-tert Highly efficient blue-green emission by using 2-butylanthracene (abbreviation: DPABPA) In addition, anthracene derivatives substituted with an amino group at the 2-position exhibited highly efficient green emission. Since N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl is preferably obtained, Phenyl-9H-carbazol-3-amine (abbreviation: 2PCAPA) has a particularly long life. As the host material, anthracene derivatives are preferable, and the above-mentioned C zPA is preferred because it is electrochemically stable. In addition, it combines green and blue emission. In the case of fabricating a light-emitting device having two peaks in the blue to green wavelength region, An electron-transporting anthracene derivative such as CzPA is used as the host for the green light-emitting layer. When a hole-transporting aromatic amine compound such as NPB is used in the This is preferable because light emission can be obtained at the interface with the layer. As the host for the color emitting material, an aromatic amine compound such as NPB is preferred.

[0117] Yellow to orange light is emitted from, for example, rubrene, 4-(dicyanomethylene)-2-[p-(di Methylamino)styryl]-6-methyl-4H-pyran (abbreviation: DCM1), 4-(diphenyl (Abbreviation: 2-methyl-6-(9-julolidyl)ethynyl-4H-pyran :DCM2), Bis[2-(2-thienyl)pyridinato]acetylacetonatoiridium (Ir(thp) 2(acac)), bis(2-phenylquinolinato)acetylacetonate Iridium (Ir(pq) 2 (acac)) as a guest material, and In particular, the guest material can be a tetramer such as rubrene. The thracene derivative is preferred because it is highly efficient and chemically stable. As the host material, an aromatic amine compound such as NPB is preferable. Zn(8-quinolinolato)zinc (abbreviation: Znq 2 ) and bis[2-cinnamoyl-8-quinolinyl Norato]zinc (abbreviation: Znsq 2 Metal complexes such as poly( 2,5-dialkoxy-1,4-phenylenevinylene) and other polymers may also be used.

[0118] Orange to red light can be emitted, for example, from 4-(dicyanomethylene)-2,6-bis[p-(dimethyl 2-(2-{2-[4 -(Dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyran-4-ylidene ) Propanedinitrile (abbreviation: DCM1), 4-(dicyanomethylene)-2-methyl-6 -(9-julolidyl)ethynyl-4H-pyran (abbreviation: DCM2), bis[2-(2- Thienyl)pyridinato]acetylacetonatoiridium (Ir(thp) 2 (acac) ), etc. as guest materials and dispersed in a suitable host material. Bis(8-quinolinolato)zinc (abbreviation: Znq 2 ) and bis[2-cinnamoyl-8-oxo Norinolato] Zinc (abbreviation: Znsq 2 ) and other metal complexes. Polymers such as poly(3-alkylthiophene) may also be used. The materials used were 4-(dicyanomethylene)-2,6-bis[p-(dimethylamino)styrene] 2-(2-[4-(dimethylamino) )phenyl]ethenyl}-6-methyl-4H-pyran-4-ylidene)propanedinitri DCM1, 4-(dicyanomethylene)-2-methyl-6-(9-dihydropyridine) ethynyl-4H-pyran (abbreviation: DCM2), {2-isopropyl-6-[2-(2 ,3,6,7-Tetrahydro-1,1,7,7-tetramethyl-1H,5H-benzo[i j]Quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanidine DCJTI, {2,6-bis[2-(2,3,6,7-tetrahydro-8 -Methoxy-1,1,7,7-tetramethyl-1H,5H-benzo[ij]quinolizine- 9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: Bi 4H-pyran derivatives such as DCJT are highly efficient and are preferred. I, BisDCJTM is preferred because it has an emission peak at about 620 nm.

[0119] In the above-mentioned structure, a suitable host material is a light-emitting material rather than a light-emitting organic compound. It is sufficient that the light color is of short wavelength or has a large energy gap. Specifically, the material is appropriately selected from the hole transport material and the electron transport material typified by the examples shown in the first embodiment. In addition, 4,4'-bis(N-carbazolyl)biphenyl (abbreviation: C BP), 4,4',4''-tris(N-carbazolyl)triphenylamine (abbreviation: T CTA), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB) may also be used.

[0120] The light-emitting element shown in this embodiment has an emission spectrum of the first EL layer and an emission spectrum of the second EL layer. As a result of the overlapping of emission spectra, the wavelength ranges from blue to blue-green and blue-green to green are , white light emission that broadly covers the yellow to orange wavelength region and the orange to red wavelength region can be obtained. .

[0121] In addition, by adjusting the thickness of each layer and intentionally causing slight interference of light, it is possible to obtain sharp peaks. The generation of peaks is suppressed, and the emission spectrum is made trapezoidal, resulting in a continuous spectrum. It is also possible to adjust the thickness of each layer to intentionally cause slight interference of light. By changing the position of the peak in the emission spectrum, the position of the peak in the emission spectrum can be changed. The thickness of each layer is adjusted so that the multiple peak intensities that appear are almost the same. By narrowing the interval between the peaks, it is possible to obtain white light with an emission spectrum closer to a trapezoid. can be obtained.

[0122] In this embodiment, the light emitting layers each have a complementary color. By overlapping the different luminescent colors, an EL layer that emits white light is obtained. A specific configuration of an EL layer that emits white light due to the complementary color relationship will be described.

[0123] The EL layer provided in the light-emitting element shown in this embodiment mode is made of a material having a high hole-transporting property, for example. A first layer including a first light-emitting substance and a second layer including a substance having high hole transport properties and a second light-emitting substance. The second layer and the third layer containing a material with high electron transport properties and a second light-emitting material are disposed between the anode 101 and the second light-emitting material. The layers may be stacked in this order.

[0124] In order to obtain white light emission in the EL layer of the light-emitting element shown in this embodiment, Both the EL material and the second emissive material must emit light. Therefore, the carriers in the EL layer In order to adjust the transport property of the hole, a substance having a high hole transport property and a substance having a high electron transport property are used. It is preferable that the host material is used as the hole transporting material. As the substance having a high electron transporting property or a substance having a high electron transporting property, the substances exemplified in Embodiment 1 can be appropriately used. There can be.

[0125] In addition, the first luminescent material and the second luminescent material have complementary luminescent colors. The materials can be selected and used. Complementary colors include blue and yellow, or blue-green. Examples of materials that emit blue, yellow, blue-green, and red light include: The light emitting material may be appropriately selected from the above-listed light emitting materials. By making the wavelength shorter than the emission wavelength of the first luminescent material, the excitation energy of the second luminescent material A part of the luminescent material can be transferred to the first luminescent material to cause the first luminescent material to emit light. Therefore, in the light-emitting element of this embodiment, the emission peak wavelength of the second light-emitting substance However, it is preferable that the wavelength of the first light-emitting substance is shorter than the emission peak wavelength of the first light-emitting substance.

[0126] The structure of the light-emitting element shown in this embodiment mode is such that light is emitted from a first light-emitting substance and light is emitted from a second light-emitting substance. Both of the luminescence from the first luminescent material and the luminescence from the second luminescent material are obtained, and the luminescence colors of the first luminescent material and the second luminescent material are complementary to each other. Since the above relationship exists, white light can be emitted. This allows a light emitting element with a long life to be obtained.

[0127] Note that the structure described in this embodiment mode may be used in appropriate combination with structures described in other embodiment modes. It is assumed that it is possible to

[0128] (Embodiment 6) In this embodiment, one mode of a light-emitting device including the light-emitting element described in the above embodiment will be described. This will be explained with reference to Fig. 5. Fig. 5 is a cross-sectional view of the light emitting device.

[0129] In FIG. 5, the dotted square indicates a circuit for driving the light emitting element 12. The light-emitting element 12 has a first electrode 13, a second electrode 14, and The organic compound-containing layer 15 is disposed between the layers 11 and 12, and the organic compound-containing layer 15 is n (n is a natural number of 2 or more). ) EL layers, m (m is a natural number, 1≦m≦n-1)th EL layer and (m+1)th EL layer Between the first EL layer and the second EL layer, there are, in order from the anode side, an electron injection buffer, an electron relay layer, and a charge Each EL layer is a layer including a light-emitting layer. In addition to the light-emitting layer, a hole injection layer, a hole transport layer, an electron transport layer, or an electron injection layer is appropriately provided. That is, the light emitting element 12 has the structure shown in any one of the first to fourth embodiments. The drain region of the transistor 11 and the first electrode 13 are connected to a first interlayer insulating film 1 6 (16a, 16b, 16c) are electrically connected by a wiring 17 passing through the In addition, the light emitting element 12 is separated from another light emitting element provided adjacent to it by the partition layer 18. The light emitting device of the present embodiment having such a configuration is The semiconductor device is provided on a substrate 10 .

[0130] In addition, the transistor 11 shown in FIG. 5 has a gate electrode on the opposite side to the substrate with the semiconductor layer at the center. The transistor 11 is a top-gate type having an electrode. There is no particular limitation on the type, and it may be, for example, a bottom gate type. The type has a protective film formed on the semiconductor layer that forms the channel (channel protection type). Alternatively, a part of the semiconductor layer forming the channel is recessed (channel etch). type) is also acceptable.

[0131] The semiconductor layer constituting the transistor 11 may be either crystalline or non-crystalline. In addition, a microcrystalline semiconductor, an oxide semiconductor, or the like may be used. stomach.

[0132] The oxide semiconductor layer is made of a material selected from indium, gallium, aluminum, zinc, and tin. For example, zinc oxide (ZnO), zinc oxide Indium oxide (IZO) and oxide made of indium oxide, gallium oxide, and zinc oxide An example of such a material is IGZO. The materials are made of single crystal or polycrystalline silicon, silicon germanium, etc. These may be formed by laser crystallization, or may be formed, for example, by using nickel. It may be formed by crystallization using a solid phase growth method such as a quartz crystal.

[0133] In addition, when the semiconductor layer is made of an amorphous material, for example, amorphous silicon, The transistor 11 and other transistors (which constitute a circuit for driving a light-emitting element) The transistors that are all N-channel transistors are light-emitting devices that have circuits that are all N-channel transistors. In addition, many oxide semiconductors, such as zinc oxide (ZnO), Indium oxide (IZO) containing indium oxide, gallium oxide, and zinc oxide Since IGZO and other compounds are N-type semiconductors, transistors with these compounds as active layers are The transistors are N-channel type. The rest are N-channel or P-channel type. The light-emitting device may have a circuit formed of either one of the transistors, or may have a circuit formed of both the transistors. The light emitting device may have a circuit configured with a transistor.

[0134] Furthermore, the first interlayer insulating film 16 may be a multi-layer film as shown in FIGS. 5(A) and 5(C). The layer 16a may be made of an inorganic material such as silicon oxide or silicon nitride, and the layer 16b may be made of an inorganic material such as silicon oxide or silicon nitride. The skeleton of silicone is made up of acrylic or siloxane (a compound made up of silicon (Si) and oxygen (O) bonds). (an organic group containing at least hydrogen in the substituent) and a self-flattening material such as silicon oxide that can be applied to form a film. Furthermore, 16c is made of a silicon nitride film containing argon (Ar). There is no particular limitation on the materials constituting each layer, and materials other than those described here may be used. In addition, layers made of materials other than these may be further combined. The first interlayer insulating films 16a to 16c are formed using both inorganic and organic materials. Alternatively, the insulating film may be formed of either an inorganic film or an organic film.

[0135] The partition layer 18 preferably has an edge portion with a continuously changing radius of curvature. The partition layer 18 is formed using acrylic, siloxane, resist, silicon oxide, etc. The partition layer 18 may be formed of either an inorganic film or an organic film. It may be formed by using either one or both of them.

[0136] In addition, in FIGS. 5A and 5C, only the first interlayer insulating films 16a to 16c are formed in the transistor 1. 5B, the first interlayer insulating film is provided between the light emitting element 1 and the light emitting element 12. In addition to the insulating film 16 (16a, 16b), a second interlayer insulating film 19 (19a, 19b) is provided. In the light-emitting device shown in FIG. 5(B), the first electrode 13 is a second layer. It penetrates the interlayer insulating film 19 and is connected to the wiring 17 .

[0137] The second interlayer insulating film 19 may be a multilayer film, similar to the first interlayer insulating film 16, or a single layer film. 19a is a siloxane (a compound with a skeleton formed by bonds between silicon (Si) and oxygen (O)) (organic group having a structure and containing at least hydrogen in the substituent), silicon oxide that can be applied to form a film, etc. It is made of a material having self-flatness. Furthermore, 19b is a silicon nitride film containing argon (Ar). The materials constituting each layer are not particularly limited, and may be any of the materials described above. Other materials may be used. In addition, layers made of materials other than these may be further combined. In this way, the second interlayer insulating films 19a and 19b are made of both inorganic and organic materials. Alternatively, it may be formed of either an inorganic film or an organic film. stomach.

[0138] In the light-emitting element 12, both the first electrode and the second electrode are made of a light-transmitting material. In this case, as shown by the white arrow in FIG. 5(A), the first electrode 13 side and Light can be emitted from both sides of the second electrode 14. When the material is transparent, as shown by the white arrow in Figure 5(B), In this case, the light emitted can be extracted only from the second electrode 14 side. It is made of a highly reflective material or has a film (reflective film) made of a highly reflective material. It is preferable that the first electrode 13 is provided below the first electrode 13. If it is made of a photochromic material, as shown by the white arrow in Figure 5(C), Light can be emitted only from the first electrode 13 side. In this case, the second electrode 14 is The second electrode 14 is made of a material with a high reflectivity, or a reflective film is provided above the second electrode 14. It is preferable that

[0139] In addition, in the light-emitting element 12, the potential of the second electrode 14 becomes higher than the potential of the first electrode 13. The layers 15 may be laminated so as to operate when a voltage is applied as shown in FIG. Alternatively, a voltage is applied so that the potential of the second electrode 14 is lower than the potential of the first electrode 13. Alternatively, the layer 15 may be laminated so that it operates when the In the latter case, transistor 11 is an N-channel transistor, and in the latter case, transistor 12 is a P-channel transistor. It is a transistor of the CMOS type.

[0140] Although only one light-emitting element is shown in the cross-sectional view of FIG. 5, a plurality of light-emitting elements are The light emitting elements R (red), G (green), and B (blue) are arranged in a matrix. When displaying a color image consisting of three color elements, three types of light (R, G, B) are emitted from the pixel area. A plurality of light emitting elements are formed. The number of color elements is not limited to three, and may be four. You can use the above, or you can use colors other than RGB. For example, add white to RGB. It is also possible to use W (W is white).

[0141] To create light-emitting elements with different color elements, each EL layer is painted separately. All EL layers are formed to emit white light and combined with color filters. A method for obtaining light-emitting elements of different colors by using the same material, and a method for making all EL layers emit blue or light of a different color. By combining it with a color conversion layer, different color elements can be obtained. For example, a method for obtaining a light emitting device according to the above can be used.

[0142] As described above, in this embodiment, an amplifier that controls driving of a light-emitting element by a transistor is provided. The active matrix type light emitting device has been described above. A passive matrix type that drives a light emitting element without providing the element on the same substrate as the light emitting element. FIG. 6A shows a light-emitting device according to any one of the first to fourth embodiments. FIG. 6(B) is a perspective view of a passive matrix light-emitting device manufactured by applying the semiconductor device. ) is a cross-sectional view taken along dashed line XY in FIG. 6(A).

[0143] In FIG. 6, on a substrate 951, an organic compound is included between an electrode 952 and an electrode 956. The layer containing the organic compound is a layer of n layers (n is a natural number of 2 or more). L layers, m (m is a natural number, 1≦m≦n-1)th EL layer and (m+1)th EL layer. Between the layers, in order from the anode side, there are an electron injection buffer, an electron relay layer, and a charge generation region. Each EL layer is provided with at least a light-emitting layer, In addition to the light-emitting layer, a hole injection layer, a hole transport layer, an electron transport layer, or an electron injection layer is appropriately provided. The end of the electrode 952 is covered with an insulating layer 953. The sidewall of the partition layer 954 is gradually narrower toward the substrate surface. It is preferable that the side wall has a slope such that the distance between the side wall and the other side wall becomes narrower. The cross section of the partition layer 954 in the short side direction is trapezoidal, and the bottom side (similar to the surface direction of the insulating layer 953) The side in contact with the insulating layer 953 is oriented in the same direction as the surface direction of the insulating layer 953. The side of the partition layer 954 facing the insulating layer 953 is shorter than the side of the partition layer 954 not in contact with the insulating layer 953. This prevents defects in the light-emitting element caused by static electricity, etc. The light-emitting device also includes the light-emitting element described in any of the first to fourth embodiments. Thus, a light emitting device with low power consumption can be obtained.

[0144] The light-emitting device shown in this embodiment mode uses the light-emitting element shown as an example in the above embodiment mode. Therefore, a light-emitting device with high luminance and low driving voltage and therefore low power consumption can be obtained. Cut.

[0145] (Embodiment 7) In this embodiment mode, an electronic device including the light-emitting device shown in Embodiment 6 will be described. The electronic devices described in this embodiment mode include the light-emitting devices described in any of the embodiments 1 to 4. The display unit includes a display element having high brightness, a low driving voltage, and reduced power consumption.

[0146] The electronic devices of the present embodiment include a video camera, a digital camera, and a goggle-type display. Ray, navigation systems, audio playback devices (car audio, audio components, etc.) , computers, game devices, personal digital assistants (mobile computers, mobile phones, portable game consoles or e-books, etc.), image playback devices equipped with recording media (specifically, Digital l Play recording media such as Versatile Disc (DVD) and display the images. Examples of such electronic devices are shown in Figure 7. .

[0147] FIG. 7A shows an example of a mobile information terminal device 9200. The device has a built-in computer and is capable of performing various data processing operations. Examples of portable information terminal devices 9200 include PDAs (Personal Digital Audio Devices). ssistance) is one example.

[0148] The mobile information terminal device 9200 is composed of two housings, a housing 9201 and a housing 9203. The housing 9201 and the housing 9203 are foldably connected to each other at a connecting portion 9207. A display unit 9202 is incorporated in a housing 9201, and a keyboard and mouse are mounted on the housing 9203. Of course, the configuration of the portable information terminal device 9200 is not limited to the above. The display unit 9202 is not limited to a display unit, and other accessories may be provided as appropriate. The light emitting element is configured by arranging light emitting elements similar to those described in the above embodiment in a matrix. The light-emitting element has the characteristics of high luminance, low driving voltage, and low power consumption. The display portion 9202 which is formed of the light-emitting elements has the same characteristics. The power consumption of information terminal equipment is being reduced.

[0149] FIG. 7B shows an example of a digital video camera 9500 according to this embodiment. The digital video camera 9500 includes a display unit 9503 built into a housing 9501. In addition, the configuration of the digital video camera 9500 is not particularly limited. The above-mentioned configuration may be such that other auxiliary equipment is appropriately provided.

[0150] In this digital video camera, the display portion 9503 is the same as that described in the above embodiment. The light emitting element is configured by arranging similar light emitting elements in a matrix. The light emitting element is driven by a voltage The display device is characterized by its low light emission, high brightness, and low power consumption. The display unit 9503 also has similar features, so this digital video camera can achieve low power consumption. It is being done.

[0151] FIG. 7C shows an example of a mobile phone 9100 according to this embodiment. The housing 9100 is composed of two housings, a housing 9102 and a housing 9101, and a connecting part 9 The housing 9102 is connected to the display unit 9104 by a folding mechanism 103. The housing 9101 is provided with an operation key 9106. The configuration of 9100 is not particularly limited, and other auxiliary equipment may be appropriately provided. Cut.

[0152] In this mobile phone, the display portion 9104 has a display device similar to that described in the above embodiment mode. The light emitting element is configured by arranging optical elements in a matrix. The display unit 91 is made up of the light-emitting elements. The 04 also has similar features, so this mobile phone is designed to consume less power. The above embodiment is applied to the backlight of a display provided in a mobile phone or the like. A light emitting element may also be used.

[0153] FIG. 7D shows an example of a portable computer 9400. The electronic device 9400 includes a housing 9401 and a housing 9404 that are connected in an openable and closable manner. A display unit 9402 is incorporated in the housing 9404, and a keyboard 9403 and the like are provided in the housing 9404. The configuration of the computer 9400 is not particularly limited, and other auxiliary equipment may be provided as appropriate. The configuration can be as follows.

[0154] In this computer, the display unit 9402 is the same as that described in the above embodiment mode. The light emitting elements are arranged in a matrix. The light emitting elements have high brightness and a driving voltage The display unit 9 is made up of the light-emitting element. The 402 also has similar features, making this computer low power consumption.

[0155] FIG. 7(E) shows an example of a television device 9600. The display unit 9603 is incorporated in the housing 9601. In addition, the case 9601 is supported by a stand 9605. 1 shows a supported configuration.

[0156] The television device 9600 can be operated using an operation switch on the housing 9601 or a separate remote control. This can be done by the remote control operation device 9610. The channel and volume can be controlled by the 9609, and the display 9603 shows In addition, the remote control unit 9610 can control the video. A display portion 9607 for displaying information output from 9610 may be provided.

[0157] The television device 9600 includes a receiver and a modem. It can receive more general television broadcasts, and can also be connected to a modem via wired or wireless connection. By connecting to a network, communication can be one-way (sender to receiver) or two-way. It is also possible to communicate information (between a sender and a receiver, or between receivers).

[0158] In this television device, at least one of the display unit 9607 and the display unit 9603 is The light emitting element is configured by arranging light emitting elements similar to those described in the above embodiment in a matrix. The light-emitting element has the characteristics of high luminance, low driving voltage, and low power consumption. The display section, which is made up of the light-emitting elements, has the same characteristics.

[0159] As described above, the light emitting device shown in the above embodiment has a very wide range of application. It is possible to apply the above to electronic devices in a wide range of fields. By using the light-emitting element shown in FIG. 1, a display portion that emits light with high luminance and consumes low power is provided. It is therefore possible to provide electronic devices that can

[0160] The light-emitting device described in the above embodiment can also be used as a lighting device. One mode in which the light-emitting device described in this embodiment is used as a lighting device will be described with reference to FIG.

[0161] FIG. 8 shows a light emitting device, an example of which is shown in the above embodiment, as a desk lamp, which is a lighting device, and The desk lamp shown in FIG. 8 is an example of a light source 3000 used as a lighting device for indoor use. As the light source 3000, the light emitting device exemplified in the above embodiment is used. Therefore, a light emitting device with low power consumption can be obtained. Since the light emitting device can be used for illumination of a large area, Since the LED is thin and consumes low power, it can be used as a thin, low-power lighting device. In addition, since the light emitting device can be made flexible, it can be used in, for example, lighting equipment. As shown in the device 3002, it is possible to provide a roll-type lighting device. The light-emitting device shown in FIG. 7(E) was installed in a room as indoor lighting devices 3001 and 3002. A television set, such as that described above, may also be installed.

[0162] As described above, the light-emitting device shown in the sixth embodiment has a very wide range of applications, and can be used in a wide variety of fields. The present embodiment can be applied to electronic devices. It can be used in appropriate combination with form 5. EXAMPLES

[0163] In this example, a light-emitting element which is one embodiment of the present invention will be described with reference to FIG. The chemical formulas of the materials used in the Examples and Examples 2 to 6 are shown below.

[0164] [ka]

[0165] A method for fabricating the light-emitting element 1 of this example and the comparative light-emitting element 1 will be described below.

[0166] First, the light-emitting element 1 will be described (see FIG. 9(A)). A first electrode 2101 is formed by depositing indium tin oxide containing silicon by a sputtering method. The film thickness was 110 nm, and the electrode area was 2 mm × 2 mm.

[0167] Next, the first electrode 2101 is placed on the substrate 1 so that the surface on which the first electrode 2101 is formed faces downward. The substrate on which the film was formed was fixed to a substrate holder provided in a vacuum deposition apparatus, and the substrate was heated for 10 -4 About Pa After the pressure was reduced to 100 MPa, 4,4′-bis(4,4′-tetrafluoroethylene) having a high hole transporting property was applied onto the first electrode 2101. [N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB) and By co-evaporating molybdenum (VI) oxide, which is a photocatalytic material, A first charge generation region 2103a was formed including a composite material formed by compounding with an organic compound. The film thickness was 50 nm, and the ratio of NPB to molybdenum (VI) oxide was 4:1 by weight. (=NPB:molybdenum oxide). This is a deposition method in which deposition is carried out simultaneously from multiple evaporation sources in a chamber.

[0168] Next, NPB is deposited on the first charge generation region 2103a by a deposition method using resistance heating. A film having a thickness of 0 nm was formed to form a hole transport layer 2103b.

[0169] In addition, 9-[4-(N-carbazolyl)]phenyl-10-phenylanthracene ( abbreviation: CzPA) and 9,10-bis{4-[N-(4-diphenylaminophenyl)- N-Phenylamino]phenyl}-2-tert-butylanthracene (abbreviation: DPAB PA) was co-evaporated to form a light-emitting layer having a thickness of 30 nm on the hole transport layer 2103b. 2103c was formed. Here, the weight ratio of CzPA to DPABPA was 1:0.1 (= The mixture was adjusted to have a molecular weight of 1000:1, and the molecular weight of the polymer was 1000:1, and the molecular weight of the polymer was 1000:1. The guest material, DPABPA, emits blue-green light.

[0170] Then, by using a vapor deposition method by resistance heating, tris(8-quinolinola) was deposited on the light-emitting layer 2103c. g) Aluminum (abbreviation: Alq) is formed into a film having a thickness of 10 nm, and the electron transport layer 2 is formed. As a result, the first charge generation region 2103a and the hole transport layer 210 3b, forming a first EL layer 2103 including a light-emitting layer 2103c, and an electron-transporting layer 2103d. did.

[0171] Next, bathophenanthroline (abbreviation: BPhen) and lithium (Li) are co-evaporated. As a result, an electron injection buffer 2104 having a thickness of 10 nm is formed on the electron transport layer 2103d. Here, the weight ratio of BPhen to Li was 1:0.02 (=BPhen:Li). The results were adjusted to satisfy i).

[0172] Then, 3,4,9,10-perylenetetracarboxylic bisbenzimidazole (abbreviation: PTCBI) was evaporated onto the electron injection buffer 2104 at 3 nm. The electron relay layer 2105 was formed with a thickness of 100 nm. The results of counter voltammetry (CV) measurements indicate that the potential is approximately -4.0 eV.

[0173] Next, on the electron relay layer 2105, NPB, which is a material with high hole transport properties, and an acceptor The second charge generation region was formed by co-evaporating molybdenum(VI) oxide, a photosensitive material. The thickness of the film was 20 nm, and the ratio of NPB to molybdenum (VI) oxide was The ratio was adjusted to a weight ratio of 4:1 (=NPB:molybdenum oxide).

[0174] Next, a second EL layer 2107 was formed on the second charge generating region 2106. The manufacturing method is as follows: first, NP is formed on the second charge generating region 2106 by a deposition method using resistance heating. B was deposited to a thickness of 10 nm to form a hole transport layer 2107a.

[0175] Then, tris(8-quinolinolato)aluminum (abbreviation: Alq) and 4-dicyano Methylene-2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6 ,7-Tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]- 4H-pyran (abbreviation: DCJTI) and A light-emitting layer 2107b having a thickness of 40 nm was formed on the substrate. The ratio of the amounts was adjusted to 1:0.01 (=Alq:DCJTI). It is a substance with electron transport properties, and the guest material DCJTI emits red light. be.

[0176] Next, on the light-emitting layer 2107b, Alq was deposited to a thickness of 10 nm, and then BPhen was deposited to a thickness of 20 nm. The electron transport layer 2107c was formed by deposition and lamination. Lithium fluoride (LiF) is evaporated to a thickness of 1 nm on the top of the electron injection layer 2107. As a result, a hole transport layer 2107a, a light emitting layer 2107b, and an electron transport layer 2107d were formed. 107c, a second EL layer 2107 including an electron injection layer 2107d was formed.

[0177] Finally, aluminum was deposited on the electron injection layer 2107d by 2000 sintering using a resistive heating deposition method. The second electrode 2102 is formed by depositing the second electrode 2102 to a thickness of 0 nm. A light-emitting element 1 was produced.

[0178] Next, comparative light-emitting element 1 will be described (see FIG. 9B). Comparative light-emitting element 1 emits This is a structure in which the electronic relay layer 2105 is removed from the element 1, and the other layers are light-emitting elements. In the comparative light-emitting element 1, the electron injection buffer 2 was After forming 104, a second charge generating region 2106 is formed on the electron injection buffer 2104. In this manner, the comparative light-emitting element 1 of this example was obtained.

[0179] Table 1 below shows the element structures of the light-emitting element 1 and the comparative light-emitting element 1.

[0180] [Table 1]

[0181] The light-emitting element 1 and the comparative light-emitting element 1 obtained above were placed in a glove box with a nitrogen atmosphere. In the step 1, each light emitting element is sealed so as not to be exposed to the atmosphere. The operating characteristics of the device were measured. The measurements were performed at room temperature (an atmosphere maintained at 25°C). So I went.

[0182] FIG. 10 shows the voltage-luminance characteristics of the light-emitting element 1 and the comparative light-emitting element 1. The axis is the applied voltage (V), and the vertical axis is the luminance (cd / m 2 ) and the current density vs. The temperature characteristics are shown in Fig. 11. In Fig. 11, the horizontal axis represents voltage (V) and the vertical axis represents current density (mA / cm 2 ) and 1000cd / m 2 The main initial characteristic values ​​of each element in the vicinity are as follows: This is summarized in Table 2.

[0183] [Table 2]

[0184] As can be seen from the CIE chromaticity coordinates in Table 2, both the light-emitting element 1 and the comparative light-emitting element 1 This is due to the DPABPA contained in the first EL layer 2103. The blue-green emission originates from the second EL layer 2107, and the red emission originates from the DCJTI contained in the second EL layer 2108. Because we got both.

[0185] As shown in FIG. 10, the light-emitting element 1 has a high luminance with respect to the voltage by providing an electron relay layer. 11, the light-emitting element 1 has a higher emission efficiency than the comparative light-emitting element 1. It can be seen that the current density is high.

[0186] From the above, it was confirmed that the light-emitting element 1 of this embodiment has characteristics as a light-emitting element and functions sufficiently. It was also confirmed that the light-emitting element 1 can be driven at a low voltage. Ta. EXAMPLES

[0187] In this example, a light-emitting element which is one embodiment of the present invention will be described with reference to FIG. In the light-emitting element and the comparative light-emitting element shown in this embodiment, the same parts as those in the above-described embodiment or Parts having similar functions are given the same reference numerals, and repeated explanations will be omitted.

[0188] A method for fabricating the light-emitting element 2 of this example and the comparative light-emitting element 2 will be described below.

[0189] First, the light emitting element 2 will be described (see FIG. 12(A)). Up to the child relay layer 2105, the light-emitting element 1 shown in Example 1 was fabricated in the same manner. In the light-emitting element 2, molybdenum oxide, which is an acceptor material, is formed on the electron-relay layer 2105. Then, 20 nm of dendrimer (VI) was evaporated, followed by 10 nm of NPB, a material with high hole transport properties. By lamination, a second charge generation region 2106 was formed.

[0190] Next, a second EL layer 2108 was formed on the second charge generating region 2106. The method of preparation is as follows: first, Alq and DCJTI are co-deposited to form the second charge generating region. A light-emitting layer 2108a having a thickness of 40 nm was formed on the region 2106. The weight ratio of Alq to DCJTI was adjusted to 1:0.01 (=Alq:DCJTI). Alq is a substance with electron transport properties, and the guest material DCJTI emits red light. It is a substance that shows this.

[0191] Next, on the light-emitting layer 2108a, Alq was deposited to a thickness of 10 nm, and then BPhen was deposited to a thickness of 20 nm. The electron transport layer 2108b was formed by deposition and lamination. Lithium fluoride (LiF) is evaporated to a thickness of 1 nm on the surface to form an electron injection layer 2108. As a result, a light-emitting layer 2108a, an electron transport layer 2108b, and an electron injection layer 2108c were formed. A second EL layer 2108 was formed that included 108c.

[0192] Finally, aluminum was deposited on the electron injection layer 2108c by evaporation using resistance heating. The second electrode 2102 is formed by depositing the second electrode 2102 to a thickness of 0 nm. A light-emitting element 2 was fabricated.

[0193] Next, the comparative light-emitting element 2 will be described (see FIG. 12(B)). The element 2 has a structure in which the electronic relay layer 2105 is removed from the light-emitting element 2, and the other layers are The comparative light-emitting element 2 was fabricated by the same method as that for the light-emitting element 2. After the buffer 2104 is formed, a second charge generation region is formed on the electron injection buffer 2104. Thus, the comparative light-emitting element 2 of this example was obtained.

[0194] Table 3 below shows the element structures of the light-emitting element 2 and the comparative light-emitting element 2.

[0195] [Table 3]

[0196] The light-emitting element 2 and the comparative light-emitting element 2 obtained above were placed in a glove box with a nitrogen atmosphere. In the step 1, each light emitting element is sealed so as not to be exposed to the atmosphere. The operating characteristics of the device were measured. The measurements were performed at room temperature (an atmosphere maintained at 25°C). So I went.

[0197] FIG. 13 shows the voltage-luminance characteristics of the light-emitting element 2 and the comparative light-emitting element 2. The axis is the applied voltage (V), and the vertical axis is the luminance (cd / m 2 ) and the current density vs. The temperature characteristics are shown in FIG. 14. In FIG. 14, the horizontal axis represents voltage (V) and the vertical axis represents current density (mA / cm 2 ) and 1000cd / m 2 The main initial characteristic values ​​of each element in the vicinity are as follows: The details are summarized in Table 4.

[0198] [Table 4]

[0199] As can be seen from the CIE chromaticity coordinates in Table 4, both the light-emitting element 2 and the comparative light-emitting element 2 This is due to the DPABPA contained in the first EL layer 2103. The blue-green emission originates from the second EL layer 2108, and the red emission originates from the DCJTI contained in the second EL layer 2108. Because we got both.

[0200] As shown in FIG. 13, the light-emitting element 2 has a high luminance with respect to the voltage by providing an electron relay layer. 14, the light-emitting element 2 has a higher emission efficiency than the comparative light-emitting element 2. It can be seen that the current density is high.

[0201] From the above, it was confirmed that the light-emitting element 2 of this embodiment has characteristics as a light-emitting element and functions sufficiently. It was also confirmed that the light-emitting element 2 can be driven at a low voltage. Ta. EXAMPLES

[0202] In this example, a light-emitting element which is one embodiment of the present invention will be described with reference to FIG. In the light-emitting element and the comparative light-emitting element shown in this embodiment, the same parts as those in the above-described embodiment or Parts having similar functions are given the same reference numerals and repeated explanations will be omitted.

[0203] A method for fabricating the light-emitting element 3 of this example and the comparative light-emitting element 3 will be described below.

[0204] First, the light emitting element 3 will be described (see FIG. 9(A)). The light emitting element 3 of this embodiment is a first The EL layer 2103 is made of a material other than the electron transport layer 2103d and the electron injection buffer 2104. The light-emitting device 3 of this example was fabricated in the same manner as the light-emitting device 1 of Example 1. On 2103c, Alq is deposited to a thickness of 10 nm, and then BPhen is deposited to a thickness of 10 nm. In this way, an electron transport layer 2103d was formed.

[0205] Next, lithium oxide (Li 2 O) is evaporated to 0.1 nm. In this way, an electron injection buffer 2104 was formed. I got 3.

[0206] Next, the comparative light-emitting element 3 will be described (see FIG. 9(B)). 3 is a structure in which the electron relay layer 2105 is removed from the light-emitting element 3, and the other layers are The comparative light-emitting element 3 was fabricated by the same method as that for the light-emitting element 3. After forming the electron injection buffer 2104, a second charge generation region is formed on the electron injection buffer 2104. In this manner, a comparative light-emitting element 3 of this example was obtained.

[0207] Table 5 below shows the element structures of the light-emitting element 3 and the comparative light-emitting element 3.

[0208] [Table 5]

[0209] The light-emitting element 3 and the comparative light-emitting element 3 obtained above were placed in a glove box with a nitrogen atmosphere. In the step 1, each light emitting element is sealed so as not to be exposed to the atmosphere. The operating characteristics of the device were measured. The measurements were performed at room temperature (an atmosphere maintained at 25°C). So I went.

[0210] FIG. 15 shows the voltage-luminance characteristics of the light-emitting element 3 and the comparative light-emitting element 3. The axis is the applied voltage (V), and the vertical axis is the luminance (cd / m 2 ) and the current density vs. The temperature characteristics are shown in FIG. 16. In FIG. 16, the horizontal axis represents voltage (V) and the vertical axis represents current density (mA / cm 2 ) and 1000cd / m 2 The main initial characteristic values ​​of each element in the vicinity are as follows: The details are summarized in Table 6.

[0211] [Table 6]

[0212] As can be seen from the CIE chromaticity coordinates in Table 6, both the light-emitting element 3 and the comparative light-emitting element 3 This is due to the DPABPA contained in the first EL layer 2103. The blue-green emission originates from the second EL layer 2107, and the red emission originates from the DCJTI contained in the second EL layer 2108. Because we got both.

[0213] As shown in FIG. 15, the light-emitting element 3 has a high luminance with respect to the voltage by providing an electron relay layer. 16, the light-emitting element 3 has a higher emission efficiency than the comparative light-emitting element 3. It can be seen that the current density is high.

[0214] From the above, it was confirmed that the light-emitting element 3 of this embodiment has characteristics as a light-emitting element and functions sufficiently. It was also confirmed that the light-emitting element 3 can be driven at a low voltage. Ta. EXAMPLES

[0215] In this example, a light-emitting element which is one embodiment of the present invention will be described with reference to FIG. In the light-emitting element and the comparative light-emitting element shown in this embodiment, the same parts as those in the above-described embodiment or Parts having similar functions are given the same reference numerals, and repeated explanations will be omitted.

[0216] A method for fabricating the light-emitting element 4 of this example and the comparative light-emitting element 4 will be described below.

[0217] First, the light emitting element 4 will be described (see FIG. 12(A)). The light emitting element 4 of this embodiment is The electron transport layer 2103d of the first EL layer 2103 and the electron injection buffer 2104 are not included. The light-emitting device 4 of this example was fabricated in the same manner as the light-emitting device 2 shown in Example 2. On the layer 2103c, Alq is deposited to a thickness of 10 nm, and then BPhen is deposited to a thickness of 10 nm. In this way, an electron transport layer 2103d was formed.

[0218] Next, lithium oxide (Li 2 O) is evaporated to 0.1 nm. In this way, an electron injection buffer 2104 was formed. I got 4.

[0219] Next, the comparative light-emitting element 4 will be described (see FIG. 12(B)). The element 4 has a structure in which the electronic relay layer 2105 is removed from the light-emitting element 4, and the other layers are The comparative light-emitting element 4 was fabricated in the same manner as in the light-emitting element 4. After the buffer 2104 is formed, a second charge generation region is formed on the electron injection buffer 2104. Thus, the comparative light-emitting element 4 of this example was obtained.

[0220] Table 7 below shows the element structures of the light-emitting element 4 and the comparative light-emitting element 4.

[0221] [Table 7]

[0222] The light-emitting element 4 and the comparative light-emitting element 4 obtained above were placed in a glove box with a nitrogen atmosphere. In the step 1, each light emitting element is sealed so as not to be exposed to the atmosphere. The operating characteristics of the device were measured. The measurements were performed at room temperature (an atmosphere maintained at 25°C). So I went.

[0223] FIG. 17 shows the voltage-luminance characteristics of the light-emitting element 4 and the comparative light-emitting element 4. The axis is the applied voltage (V), and the vertical axis is the luminance (cd / m 2 ) and the current density vs. The temperature characteristics are shown in FIG. 18. In FIG. 18, the horizontal axis represents voltage (V) and the vertical axis represents current density (mA / cm 2 ) and 1000cd / m 2 The main initial characteristic values ​​of each element in the vicinity are as follows: The details are summarized in Table 8.

[0224] [Table 8]

[0225] As can be seen from the CIE chromaticity coordinates in Table 8, both the light-emitting element 4 and the comparative light-emitting element 4 This is due to the DPABPA contained in the first EL layer 2103. The blue-green emission originates from the second EL layer 2108, and the red emission originates from the DCJTI contained in the second EL layer 2108. Because we got both.

[0226] As shown in FIG. 17, the light-emitting element 4 has a high luminance with respect to the voltage by providing an electron relay layer. 18, the light-emitting element 4 has a higher emission efficiency than the comparative light-emitting element 4. It can be seen that the current density is high.

[0227] From the above, it was confirmed that the light-emitting element 4 of this embodiment has characteristics as a light-emitting element and functions sufficiently. It was also confirmed that the light-emitting element 4 can be driven at a low voltage. Ta. EXAMPLES

[0228] In this example, a light-emitting element which is one embodiment of the present invention will be described with reference to FIG. In the light-emitting element and the comparative light-emitting element shown in this embodiment, the same parts as those in the above-described embodiment were used. Components or parts having similar functions are given the same reference numerals and repeated explanations thereof will be omitted.

[0229] A method for fabricating the light-emitting element 3 of this example and the comparative light-emitting element 5 will be described below.

[0230] The light-emitting device 3 of this example was fabricated in the same manner as the light-emitting device 3 shown in Example 3 (FIG. 9(A) In addition, the comparative light-emitting element 5 of this example has no light-emitting region other than the second charge generation region 2106. The comparative light-emitting element 5 of this example was fabricated in the same manner as in the element 3. A second charge generation region 2106 is formed on the substrate by depositing NPB to a thickness of 20 nm. (See FIG. 9(A)). In this manner, comparative light-emitting element 5 of this example was obtained.

[0231] Table 9 below shows the element structures of the light-emitting element 3 and the comparative light-emitting element 5.

[0232] [Table 9]

[0233] The light-emitting element 3 and the comparative light-emitting element 5 obtained above were placed in a glove box with a nitrogen atmosphere. In the step 1, each light emitting element is sealed so as not to be exposed to the atmosphere. The operating characteristics of the device were measured. The measurements were performed at room temperature (an atmosphere maintained at 25°C). So I went.

[0234] FIG. 19 shows the voltage-luminance characteristics of the light-emitting element 3 and the comparative light-emitting element 5. The axis is the applied voltage (V), and the vertical axis is the luminance (cd / m 2 ) and the current density vs. The temperature characteristics are shown in FIG. 20. In FIG. 20, the horizontal axis represents voltage (V) and the vertical axis represents current density (mA / cm 2 ) and 1000cd / m 2 The main initial characteristic values ​​of each element in the vicinity are as follows: This is summarized in Table 10.

[0235] [Table 10]

[0236] As described in Example 3, the light-emitting element 3 emitted white light, but the comparative light-emitting element 5 had weak red spectral intensity due to DCJTI and exhibited blue-green emission (Table 10 (See the chromaticity coordinates of the second charge generation region 2106.) In the case where the second EL layer 2107 is made of only NPB (in this embodiment), holes are injected into the second EL layer 2107. This suggests that this is unlikely to happen.

[0237] On the other hand, the light-emitting element 3 contains a substance having a high hole transporting property in the second charge generating region 2106 ( In this example, NPB is used) and an acceptor material (molybdenum oxide in this example) is used. Therefore, electrons are exchanged in the second charge generating region 2106, and the second charge generating region Holes and electrons are generated in the emission region 2106. The generated holes are then charged by applying a voltage. The electrons easily move on the NPB and are injected into the second EL layer 2107. It is more easily injected into the electron relay layer 2105 and reaches the first EL layer 2103. As shown in FIG. 19, the light-emitting element 3 has higher luminance than the comparative light-emitting element 5. In addition, as shown in FIG. 20, the light-emitting element 3 emits more light at a lower voltage than the comparative light-emitting element 5. It becomes possible for a current to flow.

[0238] From the above, it was confirmed that the light-emitting element 3 of this embodiment has characteristics as a light-emitting element and functions sufficiently. It was also confirmed that the light-emitting element 3 can be driven at a low voltage. Ta. EXAMPLES

[0239] In this example, a light-emitting element which is one embodiment of the present invention will be described with reference to FIGS. In the light-emitting element and the comparative light-emitting element shown in this embodiment, The same parts as those in the examples or parts having similar functions are designated by the same reference numerals, and the repeated explanations thereof will be omitted. Omitted.

[0240] The chemical formulas of the materials used in this example are shown below. Note that for materials whose structural formulas have already been shown, Omitted.

[0241] [ka]

[0242] A method for fabricating the light-emitting element 5 of this example and the comparative light-emitting element 6 will be described below.

[0243] First, the light emitting element 5 will be described (see FIG. 9(A)). The light emitting element 5 of this embodiment is a first The light-emitting layer 2103c of the first EL layer 2103 and the light-emitting layer 2107b of the second EL layer 2107 are The other components were fabricated in the same manner as in the light-emitting device 3 shown in Example 3. , CzPA, and Coumarin 30, N-(9,10-diphenyl-2-anthryl)-N,9 -diphenyl-9H-carbazol-3-amine (abbreviation: 2PCAPA) and As a result, a light-emitting layer 2103c having a thickness of 30 nm was formed on the hole transport layer 2103b. In addition, similarly to the light-emitting layer 2103c, CzPA and 2PCAPA were co-deposited to form a Then, a light-emitting layer 2107b having a thickness of 30 nm was formed on the hole-transporting layer 2107a. In the light-emitting layer 2103c and the light-emitting layer 2107b, the weight ratio of CzPA to 2PCAPA was 1:0. 05 (=CzPA:2PCAPA). Note that CzPA has electron transport properties. The guest material, 2PCAPA, emits green light. In this manner, the light-emitting device 5 of this example was obtained.

[0244] Next, the comparative light-emitting element 6 will be described (see FIG. 21). , the light-emitting element 5, the electron relay layer 2105, the charge generation region 2106, and the second EL layer 21 The other layers are formed in the same manner as for the light-emitting element 5. As shown in FIG. 21, the comparative light-emitting element 6 of this example has one EL layer between a pair of electrodes. It is a structure having layers.

[0245] In the comparative light-emitting element 6, after the electron injection buffer 2104 is formed, The second electrode 2102 was formed on the surface of the light source 2104. I had 6 children.

[0246] Table 11 below shows the element structures of the light-emitting element 5 and the comparative light-emitting element 6.

[0247] [Table 11]

[0248] The light-emitting element 5 and the comparative light-emitting element 6 obtained above were placed in a glove box with a nitrogen atmosphere. In the step 1, each light emitting element is sealed so as not to be exposed to the atmosphere. The operating characteristics of the device were measured. The measurements were performed at room temperature (an atmosphere maintained at 25°C). So I went.

[0249] FIG. 22 shows the voltage-current density characteristics of the light-emitting element 5 and the comparative light-emitting element 6. The horizontal axis is the applied voltage (V), and the vertical axis is the current density (mA / cm 2 ) is also represented. The current density-luminance characteristics are shown in Figure 23. In Figure 23, the horizontal axis is the current density (mA / cm 2 )of , the vertical axis is luminance (cd / m 2 ) and 1000cd / m 2 The main characteristics of each element in the vicinity The initial properties are summarized in Table 12 below.

[0250] [Table 12]

[0251] As shown in FIG. 22, the light-emitting element 5 of this example having two EL layers is comparatively light-emitting when the light-emitting element has one EL layer. It can be seen that when a current with the same current density as that of element 6 is passed through it, it can be driven at almost twice the voltage. 23, when a current having the same current density as that of the comparative light-emitting element 6 is applied to the light-emitting element 5, It can be seen that the luminance is almost twice as high (i.e., the current efficiency is almost twice as high). Therefore, in the light-emitting device 5 of this example, an electron injection buffer and an electron It was shown that there was almost no additional voltage rise due to the introduction of the charge generation region and the relay layer. To be tempted.

[0252] From the above, it was confirmed that the light-emitting element 5 of this embodiment has characteristics as a light-emitting element and functions sufficiently. In addition, the light-emitting element 5 has an electron injection buffer and an electron relay between the two EL layers. The introduction of the charge generation region and the charge layer results in almost no additional voltage rise, allowing operation at low voltages. It was confirmed that this is a possible light-emitting device. EXAMPLES

[0253] In this example, a light-emitting element which is one embodiment of the present invention will be described with reference to FIGS. In the light-emitting element and the comparative light-emitting element shown in this embodiment, The same parts as those in the embodiment or parts having similar functions are designated by the same reference numerals, and the repeated explanations are omitted. is omitted.

[0254] The chemical formulas of the materials used in this example are shown below. Note that for materials whose structural formulas have already been shown, Omitted.

[0255] [ka]

[0256] A method for fabricating the light-emitting element 6 of this example and the comparative light-emitting element 7 will be described below.

[0257] First, the light-emitting element 6 will be described (see FIG. 9(A)). The light-emitting element 6 of this embodiment is an electron The light-emitting device was fabricated in the same manner as in Example 6 except for the relay layer 2105. In the optical element 6, N,N'-dihexyl-3,4,9,10-perylenetetracarbazole The electron injection buffer 210 was formed by evaporating hexafluorophosphate diimide (HexPTC). An electron relay layer 2105 having a thickness of 3 nm was formed on the substrate 4. I had 6 children.

[0258] Next, the comparative light-emitting element 7 will be described (see FIG. 9(B)). The structure shown in FIG. 1 is obtained by removing the electron relay layer 2105 from the light-emitting element 6. As for the other layers, The comparative light-emitting element 7 was fabricated in the same manner as in the light-emitting element 6. After forming the first electrode 2104, a charge generation region 2106 is formed on the electron injection buffer 2104. In this manner, the comparative light-emitting element 7 of this example was obtained.

[0259] Table 13 below shows the element structures of the light-emitting element 6 and the comparative light-emitting element 7.

[0260] [Table 13]

[0261] The light-emitting element 6 and the comparative light-emitting element 7 obtained above were placed in a glove box with a nitrogen atmosphere. In the step 1, each light emitting element is sealed so as not to be exposed to the atmosphere. The operating characteristics of the device were measured. The measurements were performed at room temperature (an atmosphere maintained at 25°C). So I went.

[0262] FIG. 25 shows the voltage-luminance characteristics of the light-emitting element 6 and the comparative light-emitting element 7. The axis is the applied voltage (V), and the vertical axis is the luminance (cd / m 2 ) and the voltage-current density The temperature characteristics are shown in FIG. 26. In FIG. 26, the horizontal axis represents voltage (V) and the vertical axis represents current density (mA / cm 2 ) and 1000cd / m 2 The main initial characteristic values ​​of each element in the vicinity are as follows: The details are summarized in Table 14.

[0263] [Table 14]

[0264] As shown in FIG. 25, the light-emitting element 6 has a higher sensitivity to voltage than the comparative light-emitting element 7 due to the provision of the electronic relay layer. 26, the light-emitting element 6 has a higher luminance than the comparative light-emitting element. It can be seen that the current density is higher than that of the electrode 7.

[0265] From the above, it was confirmed that the light-emitting element 6 of this embodiment has characteristics as a light-emitting element and functions sufficiently. It was also confirmed that the light-emitting element 6 can be driven at a low voltage. Ta. EXAMPLES

[0266] In this example, a light-emitting element which is one embodiment of the present invention will be described with reference to FIGS. In the light-emitting element and the comparative light-emitting element shown in this embodiment, The same parts as those in the embodiment or parts having similar functions are designated by the same reference numerals, and the repeated explanations are omitted. is omitted.

[0267] The chemical formulas of the materials used in this example are shown below. Note that for materials whose structural formulas have already been shown, Omitted.

[0268] [ka]

[0269] A method for fabricating the light-emitting element 7 of this example and the comparative light-emitting element 8 will be described below.

[0270] First, the light emitting element 7 will be described (see FIG. 9(A)). The light emitting element 7 of this embodiment is a first The EL layer 2103 includes a light-emitting layer 2103c and an electron transport layer 2103d. Region 2106, and the light-emitting layer 2107b and the electron transport layer in the second EL layer 2107 The light-emitting element was fabricated in the same manner as in Example 3 except for 2107c.

[0271] In the light-emitting element 7 of this embodiment, the light-emitting layer 2103c is made of 4-(10-phenyl-9-anthracene). (9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA) and 4(1-naphthyl)-4'(9-phenyl-9H-carbazolyl) The film was then coated with 20 nm thick polyphenylene-3-yl-triphenylamine (PCBANB). After the deposition, CzPA and SD1 (product name; manufactured by SFC Co., Ltd.) were added for 30 The film was formed by co-evaporation with a thickness of 100 nm. The weight ratio of PCBA to B was adjusted to 1:1 (= PCBAPA: PCBANB). The weight ratio of CzPA to SD1 was adjusted to 1:0.05 (=CzPA:SD1). Adjusted.

[0272] Next, BPhen was deposited at 30 nm on the light-emitting layer 2103c to form an electron transport layer. A layer 2107c was formed.

[0273] In the light-emitting element 7, the second charge generation region 2106 is formed on the electron relay layer 2105. NPB, which has high hole transport properties, and molybdenum oxide (V The film was formed by co-evaporation of NPB and molybdenum oxide. The ratio of NPB to molybdenum (VI) was adjusted to 4:1 (=NPB:molybdenum oxide) by weight. Saved.

[0274] In the light-emitting element 7, the light-emitting layer 2107b is made of 4-(9H-carbazol-9-yl) )-4'-(5-phenyl-1,3,4-oxadiazol-2-yl)triphenyla amine (abbreviation: YGAO11) and (acetylacetonato)bis(2,3,5-triphenylphosphine) Nylpyrazinato)iridium(III) (abbreviation: Ir(tppr) 2 (acac)) and After co-evaporation to a thickness of 10 nm, YGAO11 and bis(2-phenylpyridinato N,C2') Iridium(acetylacetonate) (abbreviation: Ir(ppy) 2 (acac The film was formed by co-evaporation of YGAO11 and Ir( tppr) 2 The weight ratio of YGAO11 to Ir(tpp r) 2 (acac)). YGAO11 and Ir(ppy) 2 ( The weight ratio of YGAO11 to Ir(ppy) is 1:0.06 (=YGAO11:Ir(ppy) 2 (acac )) was adjusted.

[0275] Next, BAlq was evaporated to a thickness of 10 nm on the light-emitting layer 2107b, and then BPhen was evaporated to a thickness of 20 nm. The electron transport layer 2107c was formed by laminating the above-mentioned layers. The light-emitting element 7 was obtained.

[0276] Next, the comparative light-emitting element 8 will be described (see FIG. 9(B)). The comparative light-emitting element 8 has a structure in which the electron relay layer 2105 is omitted from the light-emitting element 7. In the present invention, the electron injection buffer 2104 is formed by co-evaporating BPhen and lithium (Li). The thickness of the film was 20 nm. The weight ratio of BPhen to Li was 1. The ratio of BPhen to Li was adjusted to 0.02 (=BPhen:Li). The comparative light-emitting element 8 was fabricated in the same manner as in the element 7. After forming 2104, a charge generation region 2106 is formed on the electron injection buffer 2104. In this manner, a comparative light-emitting element 8 of this example was obtained.

[0277] Table 15 below shows the element structures of the light-emitting element 7 and the comparative light-emitting element 8.

[0278] [Table 15]

[0279] The light-emitting element 7 and the comparative light-emitting element 8 obtained as above were placed in a glove box with a nitrogen atmosphere. After sealing the light emitting elements so that they are not exposed to the atmosphere, The operating characteristics of the device were measured. The measurements were performed at room temperature (25°C). went.

[0280] FIG. 27 shows the voltage-luminance characteristics of the light-emitting element 7 and the comparative light-emitting element 8. The axis is the applied voltage (V), and the vertical axis is the luminance (cd / m 2 ) and the voltage-current density The temperature characteristics are shown in FIG. 28. In FIG. 28, the horizontal axis represents voltage (V) and the vertical axis represents current density (mA / cm 2 ) and 1000cd / m 2 The main initial characteristic values ​​of each element in the vicinity are as follows: The details are summarized in Table 16.

[0281] [Table 16]

[0282] As shown in FIG. 27, the light-emitting element 7 has a higher sensitivity to voltage than the comparative light-emitting element 8 due to the provision of the electron relay layer. 28, the light-emitting element 7 has a higher luminance than the comparative light-emitting element. It can be seen that the current density is higher than that of electrode 8.

[0283] As can be seen from the CIE chromaticity coordinates in Table 16 and FIG. 29, the light-emitting element 7 and the comparative light-emitting element Both elements 8 emit white light. This is because the PCBA The blue light emission originates from PA and SD1, and the Ir(tp pr) 2 Red emission from (acac) and Ir(ppy) 2 (acac) This is because a green light emission was obtained.

[0284] From the above, it was confirmed that the light-emitting element 7 of this embodiment has characteristics as a light-emitting element and functions sufficiently. It was also confirmed that the light-emitting element 7 can be driven at a low voltage. In addition, one embodiment of the configuration of the present invention is a white light emitting element in which each EL layer has a different emission spectrum. It has been found to be effective even when applied to children. EXAMPLES

[0285] In this example, a light-emitting element which is one embodiment of the present invention will be described with reference to FIGS. In the light-emitting element and the comparative light-emitting element shown in this embodiment, The same parts as those in the embodiment or parts having similar functions are designated by the same reference numerals, and the repeated explanations are omitted. is omitted.

[0286] The chemical formulas of the materials used in this example are shown below. Note that for materials whose structural formulas have already been shown, Omitted.

[0287] [ka]

[0288] A method for fabricating the light-emitting element 8 of this example and the comparative light-emitting element 9 will be described below.

[0289] First, the light emitting element 8 will be described (see FIG. 9(A)). The light emitting element 8 of this embodiment is a first The light-emitting layer 2103c in the EL layer 2103, the second charge generation region 2106, the second EL The layers 2107 are the same as those in Example 8 except for the light-emitting layer 2107b and the electron transport layer 2107c. The light-emitting device was fabricated in the same manner as in the light-emitting device 7.

[0290] In the light-emitting element 8 of this embodiment, the light-emitting layer 2103c is made of 2,3-bis{4-[N-(4- Biphenylyl)-N-phenylamino]phenyl}quinoxaline (abbreviation: BPAPQ) , (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato ]Iridium(III) (abbreviation: Ir(Fdpq) 2 (acac)) at a thickness of 10 nm After co-evaporation, NPB and N,9-diphenyl-N-[4-(9,10-diphenyl-2- anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: 2PCAPPA) CzPA and 2PCAPPA were co-evaporated to a thickness of 30 nm. The film was formed by gluing and laminating.

[0291] In addition, BPAPQ and Ir(Fdpq) 2 The weight ratio of (acac) is 1:0.06 (=B PAPQ:Ir(Fdpq) 2 (acac)). The weight ratio with PCAPPA was adjusted to 1:0.1 (=NPB:2PCAPPA). The weight ratio of CzPA to 2PCAPPA was 1:0.1 (=CzPA:2PCAPPA). APPA).

[0292] In the light-emitting element 7, the second charge generation region 2106 is formed on the electron relay layer 2105. NPB, which has high hole transport properties, and molybdenum oxide (V The film was formed by co-evaporation of NPB and molybdenum oxide. The ratio of NPB to molybdenum (VI) was adjusted to 4:1 (=NPB:molybdenum oxide) by weight. Saved.

[0293] In the light-emitting element 7, the light-emitting layer 2107b is a 20 nm thick film of NPB and rubrene. After co-evaporation at a thickness of 100 nm, 9-phenyl-9'-[4-(10-phenyl-9-anthryl)fluorene phenyl]-3,3'-bi(9H-carbazole) (abbreviation: PCCPA) and N,N'-bi S[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenylstilbe YGA2S was co-deposited with 10 nm thick dimethylformamide (DMPA) and then C The film was formed by co-evaporation of zPA and YGA2S to a thickness of 20 nm. The weight ratio of NPB to rubrene was adjusted to 1:0.015 (=NPB:rubrene). The weight ratio of PCCPA to YGA2S was 1:0.05 (= PCCPA:YGA2S). The weight ratio of CzPA to YGA2S was adjusted to 1:0.05 ( = CzPA:YGA2S).

[0294] Next, BPhen is deposited at a thickness of 30 nm on the light-emitting layer 2107b to form an electron The transport layer 2107c was then formed. In this manner, the light-emitting element 8 of this example was obtained.

[0295] Next, the comparative light-emitting element 9 will be described (see FIG. 9(B)). The comparative light-emitting element 9 has a structure in which the electron relay layer 2105 is omitted from the light-emitting element 8. In the present invention, the electron injection buffer 2104 is formed by co-evaporating BPhen and lithium (Li). The thickness of the film was 20 nm. The weight ratio of BPhen to Li was 1. The ratio of BPhen to Li was adjusted to 0.02 (=BPhen:Li). The comparative light-emitting element 9 was fabricated in the same manner as in the element 8. After forming 2104, a charge generation region 2106 is formed on the electron injection buffer 2104. In this manner, a comparative light-emitting element 9 of this example was obtained.

[0296] Table 17 below shows the element structures of the light-emitting element 8 and the comparative light-emitting element 9.

[0297] [Table 17]

[0298] The light-emitting element 8 and the comparative light-emitting element 9 obtained as above were placed in a glove box with a nitrogen atmosphere. After sealing the light emitting elements so that they are not exposed to the atmosphere, The operating characteristics of the device were measured. The measurements were performed at room temperature (25°C). went.

[0299] FIG. 30 shows the voltage-luminance characteristics of the light-emitting element 8 and the comparative light-emitting element 9. The axis is the applied voltage (V), and the vertical axis is the luminance (cd / m 2 ) and the voltage-current density The temperature characteristics are shown in FIG. 31. In FIG. 31, the horizontal axis represents voltage (V) and the vertical axis represents current density (mA / cm 2 ) and 1000cd / m 2 The main initial characteristic values ​​of each element in the vicinity are as follows: The details are summarized in Table 18.

[0300] [Table 18]

[0301] As shown in FIG. 30, the light-emitting element 8 has a higher sensitivity to voltage than the comparative light-emitting element 9 due to the provision of the electronic relay layer. 31, the light-emitting element 8 has a higher luminance than the comparative light-emitting element. It can be seen that the current density is higher than that of electrode 9.

[0302] As can be seen from the CIE chromaticity coordinates in Table 18 and FIG. 32, the light-emitting element 8 and the comparative light-emitting element Both elements 9 emit white light. This is due to the Ir(F dpq) 2 The red emission from (acac) and the blue-green emission from 2PCAPPA. The yellow light emitted from the second EL layer 2107 is due to the rubrene, and the yellow light emitted from the YGA2S is due to the The blue light emitted from these four luminescent colors was obtained. This resulted in a high color rendering index (CRI) of 92.

[0303] From the above, it was confirmed that the light-emitting element 8 of this embodiment has characteristics as a light-emitting element and functions sufficiently. It was also confirmed that the light-emitting element 8 can be driven at a low voltage. In addition, one embodiment of the configuration of the present invention is a white light emitting element in which each EL layer has a different emission spectrum. It has been found to be effective even when applied to children.

[0304] (Reference example) In this reference example, the synthesis method of the materials used in the above examples will be specifically described. ≪4(1-naphthyl)-4'(9-phenyl-9H-carbazol-3-yl)-triphenylphosphine Synthesis example of PCBANB (abbreviation)≫

[0305] 4(1-naphthyl)-4'(9-phenyl-9H-carbazol-3-yl)-triphenylphosphine The synthesis scheme of nylamine is shown below (A-1).

[0306] [ka]

[0307] 1.2 g (3.0 g) of 3-(4-bromophenyl)-9-phenyl-9H-carbazole 0.9g (3.0mmol), 4-(1-naphthyl)diphenylamine, 0.5 g (5.0 mmol) of thorium tert-butoxide, bis(dibenzylidene (acetone) palladium(0), 6.0 mg (0.01 mmol), in a 50 mL three-neck flask The mixture was stirred under reduced pressure. After degassing, tri(tert-butyl)phosphine (10 wt% hexane solution) The mixture was heated at 120° C. under a nitrogen atmosphere. The mixture was reacted at RT for 4.5 hours with stirring.

[0308] After the reaction, 250 mL of toluene was added to the reaction mixture, and the suspension was dissolved in Florisil and silane. The resulting filtrate was washed with water and filtered through silica gel, alumina, and celite. The suspension was then mixed with ZnO to remove the water. The filtrate was concentrated and mixed with acetone and methanol. After adding and applying ultrasonic waves, the product was recrystallized to obtain a white powder with a yield of 1.5 g. The success rate was 82%.

[0309] Rf value in silica gel thin layer chromatography (TLC) (eluent: ethyl acetate:hexane) Xanthane = 1:10) The target substance was 0.34, 3-(4-bromophenyl)-9-phenyl -9H-carbazole is 0.46, and 4-(1-naphthyl)diphenylamine is 0.25. I did.

[0310] The compound obtained in the above step was analyzed by nuclear magnetic resonance spectroscopy ( 1 1 H NMR) was used to measure the The measurement data is shown in Figure 1. The measurement results show that the target substance, PCBANB (abbreviation), was obtained. I found out.

[0311] 1 H NMR (CDCl 3 ,300MHz):δ(ppm)=7.07 (t, J=6 .6Hz, 1H), 7.25-7.67 (m, 26H), 7.84 (d, J=7.8Hz, 1H), 7.89-7.92 (m, 1H), 8.03-8. 07 (m, 1H), 8.18 (d, J=7.8Hz, 1H), 8.35 (d, J=0.9Hz, 1H). [Explanation of symbols]

[0312] 10 Substrate 11 Transistor 12 Light emitting element 13 electrodes 14 electrodes 15 Layer containing organic compounds 16 Interlayer insulating film 17 Wiring 18 Partition layer 19 Interlayer insulating film 101 Anode 102 Cathode 103 EL layer 103-1 First light-emitting layer 103-2 Second light-emitting layer 104 Electron Injection Buffer 105 Electronic Relay Layer 106 Charge generation region 107 EL layer 107-1 Third luminescent layer 107-2 Fourth luminous layer 108 Electron transport layer 111 Fermi level of anode 112 Fermi level of cathode 113 LUMO level of the first EL layer 114 LUMO levels of the electron relay layer 115 Acceptor Levels in the Charge Generation Region 116 LUMO level of the second EL layer 330 First Emission 340 Second Emission 951 Board 952 Electrode 953 Insulation Layer 954 Partition layer 955 Layer containing organic compounds 956 Electrode 2100 Glass Substrate 2101 Electrode 2102 Electrode 2103 EL layer 2103a Charge generation region 2103b Hole transport layer 2103c Emitting layer 2103d Electron transport layer 2104 Electron Injection Buffer 2105 Electronic Relay Layer 2106 Charge generation area 2107 EL layer 2107a Hole transport layer 2107b Light-emitting layer 2107c Electron transport layer 2107d Electron injection layer 2108 EL layer 2108a Light-emitting layer 2108b Electron transport layer 2108c Electron injection layer 3000 light sources 3001 Lighting equipment 3002 Lighting equipment 9100 Mobile Phone 9101 Case 9102 Case 9103 Connection section 9104 Display section 9106 Operation key 9200 Portable information terminal equipment 9201 Case 9202 Display section 9203 Case 9205 Keyboard 9207 Connection section 9400 Computer 9401 Case 9402 Display section 9403 Keyboard 9404 Case 9500 Digital Video Camera 9501 Case 9503 Display section 9600 Television Equipment 9601 Case 9603 Display section 9605 Stand 9607 Display section 9609 Operation key 9610 Remote control device 9703 Display section

Claims

[Claim 1] The device has n (n is a natural number of 2 or more) EL layers between an anode and a cathode, Between the m-th EL layer (m is a natural number, 1≦m≦n−1) and the (m+1)-th EL layer, in this order from the anode side, a first layer comprising an alkali metal, an alkaline earth metal, a rare earth metal, an alkali metal compound, an alkaline earth metal compound, or a compound of a rare earth metal; a second layer including a substance having a high electron-transporting property and being in contact with the first layer; a light-emitting element including a region in contact with the second layer and containing a substance with a high hole-transporting property and an acceptor substance.

Images