Light-emitting devices, electronic equipment, light-emitting devices, and lighting devices

Abstract

To provide a light-emitting device having good luminous efficiency and life span and requiring a low driving voltage.SOLUTION: A light-emitting device includes an anode, a cathode, and an EL layer located between the anode and the cathode, the EL layer includes a hole injection layer, a light-emitting layer, and an electron transport layer, the hole injection layer is located between the anode and the light-emitting layer, the electron transport layer is located between the light-emitting layer and the cathode, the hole injection layer includes a first substance and a second substance, the first substance is an organic compound having hole-transporting properties and having a HOMO level of -5.7 eV or more and -5.4 eV or less, the second substance is a substance exhibiting electron accepting properties toward the first substance, and the electron transport layer is composed of a material whose resistance value is reduced by passing a current therethrough.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One aspect of the present invention is a light-emitting element, a light-emitting device, a display module, and a lighting module. The present invention relates to display devices, light-emitting devices, electronic devices, and lighting devices. One aspect of the present invention is as described above. The technical field of one aspect of the invention disclosed herein is not limited to the technical field of products, methods. , or relating to a manufacturing method. Or, one aspect of the present invention relates to a process, machine This relates to the manufacture or composition of matter. There is. Therefore, more specifically, one aspect of the technical field of the present invention disclosed herein is: Semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, lighting devices, energy storage devices, memory devices, imaging devices Examples include devices, methods for driving them, or methods for manufacturing them. . [Background technology]

[0002] Electroluminescence (EL) using organic compounds The practical application of light-emitting devices (organic EL elements) that utilize ence is progressing. The basic configuration of the device involves sandwiching an organic compound layer (EL layer) containing a light-emitting material between a pair of electrodes. That's how it works. A voltage is applied to this element to inject carriers, and the recombination of those carriers occurs. By utilizing energy, it is possible to obtain light emission from light-emitting materials.

[0003] Since such light-emitting devices are self-emissive, when used as pixels in a display, they become liquid crystals. Compared to other types, it has advantages such as higher visibility and the elimination of the need for a backlight, and flat panel displays It is suitable as a spray element. Furthermore, a display using such a light-emitting device is 、The ability to fabricate it in a thin and lightweight manner is also a significant advantage. Furthermore, it is also one of the characteristics that it has a very fast response speed.

[0004] Also, since these light-emitting devices can form the light-emitting layer continuously in two dimensions, planar light emission can be obtained. This is a characteristic that is difficult to achieve with point light sources typified by incandescent bulbs and LEDs, or linear light sources typified by fluorescent lamps. Therefore, it has high utility value as a surface light source applicable to lighting and the like.

[0005] Displays and lighting devices using such light-emitting devices are suitable for various electronic devices, but research and development are being advanced to seek light-emitting devices with better efficiency and lifespan.

[0006] In Patent Document 1, a configuration is disclosed in which a hole-transporting material having a HOMO level between the HOMO level of the first hole-transporting layer in contact with the hole-injecting layer and the HOMO level of the host material is provided between the first hole-transporting layer and the light-emitting layer.

[0007] The characteristics of light-emitting devices have been remarkably improved, but it has to be said that they are still insufficient to meet the high demands for all characteristics, including efficiency and durability. [Prior Art Documents] [Patent Documents]

[0008] [Patent Document 1] International Publication No. 2011 / 065136 Pamphlet [Summary of the Invention] [Problems to be Solved by the Invention]

[0009] Therefore, in one aspect of the present invention, an object is to provide a novel light-emitting device. Or, an object is to provide a light-emitting device with good luminous efficiency. Or, a light-emitting device with good lifespan. Or, an object is to provide a light-emitting device with a low driving voltage. That is the object.

[0010] Or, in another aspect of the present invention, an object is to provide a highly reliable light-emitting device, electronic device, and display device, respectively. Or, in another aspect of the present invention, an object is to provide a light-emitting device, electronic device, and display device with low power consumption, respectively.

[0011] The present invention only needs to solve any one of the above problems.

Means for Solving the Problems

[0012] One aspect of the present invention has an anode, a cathode, and an EL layer positioned between the anode and the cathode. The EL layer has a hole injection layer, a light-emitting layer, and an electron transport layer. The hole injection layer is positioned between the anode and the light-emitting layer. The electron transport layer is positioned between the light-emitting layer and the cathode. The hole injection layer has a first substance and a second substance. The first substance has hole transporting property and is an organic compound with its HOMO level being -5.7 eV or more and -5.4 eV or less. The second substance is a substance that shows electron accepting property to the first substance. The electron transport layer is composed of a material whose resistance value becomes smaller when an electric current flows through it. This is a light-emitting device.

[0013] Or, in another aspect of the present invention, in the above configuration, the material whose resistance value becomes smaller when an electric current flows through it includes an organometallic complex of an alkali metal or an alkaline earth metal. This is a light-emitting device. It's a vice.

[0014] Alternatively, in another aspect of the present invention, in the above configuration, the resistance value is obtained by passing the current. Materials that reduce the size include organic compounds with electron transport properties and alkali metals or alkaline earth This is a light-emitting device containing an organometallic complex of a metal group.

[0015] Alternatively, in another aspect of the present invention, in the above configuration, the alkali metal or alkaline earth This is a light-emitting device in which organometallic complexes of metal-like materials form clusters.

[0016] Alternatively, in another aspect of the present invention, in the above configuration, the alkali metal or alkaline earth Organometallic complexes of metals include ligands containing nitrogen and oxygen, and alkali metals or alkalis. This is a light-emitting device that is a metal complex containing earth metals.

[0017] Alternatively, in another aspect of the present invention, in the above configuration, the alkali metal or alkaline earth Organometallic complexes of metalloids include a ligand containing an 8-hydroxyquinolinate structure and a monovalent metal ion. It is a light-emitting device that is a metal complex having n.

[0018] Alternatively, in another aspect of the present invention, in the above configuration, the alkali metal or alkaline earth Organometallic complexes of metal-type compounds, lithium having ligands containing an 8-hydroxyquinolinate structure It is a light-emitting device that is a complex.

[0019] Alternatively, in another aspect of the present invention, in the above configuration, the electron transport layer comprises a first layer and a second layer The first layer is located between the light-emitting layer and the second layer, and the second layer It is located between the first layer and the cathode, and is included in the first layer and the second layer. These are light-emitting devices with varying concentrations of organometallic complexes of alkali metals or alkaline earth metals. .

[0020] Alternatively, in another aspect of the present invention, in the above configuration, the alkali metal or The concentration of the alkaline earth metal organometallic complex is the alkali metal or alkali in the second layer. This is a light-emitting device with a higher concentration than that of organometallic complexes of earth metals.

[0021] Alternatively, in another aspect of the present invention, in the above configuration, the second substance is an organic compound. It is a light-emitting device.

[0022] Alternatively, in another aspect of the present invention, in the above configuration, the light-emitting layer comprises a host material and light-emitting The device comprises a material, and the light-emitting material emits blue fluorescence.

[0023] Alternatively, in another aspect of the present invention, the above configuration includes a sensor, an operating button, a speaker, and And, Mike and, It is an electronic device that possesses [certain properties].

[0024] Alternatively, in another aspect of the present invention, in the above configuration, a transistor or a substrate and It is a light-emitting device.

[0025] Alternatively, another aspect of the present invention is a lighting device having a housing and, in the above configuration.

[0026] In this specification, the term "light-emitting device" includes image display devices that use light-emitting devices. Also, connectors, such as anisotropic conductive film or TCP (Tape) may be attached to the light-emitting device. Module with Carrier Package attached, print to TCP A module equipped with a wiring board, or a light-emitting device, with COG (Chip On Glas Modules in which ICs (integrated circuits) are directly mounted using method s) may also be included as light-emitting devices. Yes, they do. Furthermore, lighting fixtures and the like may have light-emitting devices. [Effects of the Invention]

[0027] In one aspect of the present invention, a novel light-emitting device can be provided, or a device with a good lifespan. We can provide light-emitting devices. Or, we can provide light-emitting devices with good luminous efficiency. This is possible. Alternatively, it is possible to provide a light-emitting device with a low drive voltage.

[0028] Alternatively, in another aspect of the present invention, a highly reliable light-emitting device, electronic device, and display device are provided, respectively. It can be provided. Or, in another aspect of the present invention, a light-emitting device with low power consumption, Electronic devices and display devices can be provided, respectively.

[0029] Furthermore, the description of these effects does not preclude the existence of other effects. The embodiment does not necessarily have to have all of these effects. Furthermore, other effects are... This will become clear from the description in the specification, drawings, claims, etc., and the specification, drawings Furthermore, it is possible to extract other effects from the descriptions in the claims and other documents. [Brief explanation of the drawing]

[0030] [Figure 1] Figures 1(A1), 1(A2), 1(B), and 1(C) are schematic diagrams of light-emitting devices. [Figure 2] Figures 2(A) and 2(B) illustrate the concept of extending lifespan. [Figure 3] Figures 3(A) and 3(B) illustrate the increase in brightness. [Figure 4] Figures 4(A) and 4(B) are conceptual diagrams of an active matrix type light-emitting device. [Figure 5] Figures 5(A) and 5(B) are conceptual diagrams of an active matrix type light-emitting device. [Figure 6] Figure 6 is a conceptual diagram of an active matrix type light-emitting device. [Figure 7] Figures 7(A) and 7(B) are conceptual diagrams of a passive matrix type light-emitting device. [Figure 8] Figures 8(A) and 8(B) are diagrams representing lighting devices. [Figure 9] Figures 9(A), 9(B1), 9(B2), and 9(C) are diagrams representing electronic devices. [Figure 10] Figures 10(A), 10(B), and 10(C) are diagrams representing electronic devices. [Figure 11] Figure 11 is a diagram representing a lighting device. [Figure 12] Figure 12 is a diagram representing a lighting device. [Figure 13] Figure 13 is a diagram representing an in-vehicle display device and lighting system. [Figure 14] Figures 14(A) and 14(B) are diagrams representing electronic devices. [Figure 15] Figures 15(A), 15(B), and 15(C) are diagrams representing electronic devices. [Figure 16] Figure 16 shows an example of a Z-plot of a light-emitting device according to one embodiment of the present invention. [Figure 17] Figure 17 shows an example of an M-plot for a light-emitting device according to one embodiment of the present invention. [Figure 18] Figure 18 shows an example of an equivalent circuit of a light-emitting device according to one embodiment of the present invention. [Figure 19] Figure 19 shows the resistance values ​​of each resistance component of a light-emitting device according to one embodiment of the present invention, before and after driving. [Figure 20] Figure 20 is a graph showing the change in brightness with respect to the operating time of light-emitting device 1 and comparison light-emitting device 1. [Figure 21] Figures 21(A) and (B) show the Z-plots of light-emitting device 1 and comparison light-emitting device 1. [Figure 22] Figure 22 shows the change in voltage with respect to the operating time of light-emitting device 1 and comparison light-emitting device 1. [Figure 23] Figure 23 shows the M-plot of the light-emitting device 1. [Figure 24] Figure 24 shows the M-plots of light-emitting devices 2 to 5 (Figure 24(A)) and the resistance values ​​before and after driving for each resistance component (Figure 24(B)). [Figure 25] Figure 25 shows the M-plots for light-emitting devices 2, 6, and 7 (Figure 25(A)) and the resistance values ​​before and after driving for each resistance component (Figure 25(B)). [Figure 26] Figure 26 shows the M-plots for light-emitting devices 2 and 8 (Figure 26(A)) and the resistance values ​​before and after driving for each resistance component (Figure 26(B)). [Figure 27] Figure 27 shows the stabilization energy per molecule in a Liq polymer. [Figure 28] Figure 28 shows the structure of the measuring element. [Figure 29] Figure 29 shows the frequency characteristics of the calculated capacitance C in ZADN:Liq(1:1) at a DC voltage of 7.0V. [Figure 30] Figure 30 shows the frequency characteristics of -ΔB for ZADN:Liq(1:1) at a DC voltage of 7.0V. [Figure 31] Figure 31 shows the electric field strength dependence characteristics of electron mobility in each organic compound. [Figure 32] Figures 32(A1), 32(A2), 32(B1), and 32(B2) show the concentration distribution of the eighth substance in the electron transport layer. [Modes for carrying out the invention]

[0031] The embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention is as follows Not limited to the description, the form and details thereof may be described without departing from the spirit and scope of the present invention. Those skilled in the art will readily understand that the invention can be modified in various ways. Therefore, the present invention is as follows: This should not be interpreted as being limited to the contents described in the embodiments.

[0032] (Embodiment 1) Figures 1(A1) and (A2) show a diagram representing a light-emitting device according to one embodiment of the present invention. The light-emitting device has an anode 101, a cathode 102, and an EL layer 103, and the EL The layer comprises a hole injection layer 111, a hole transport layer 112, a light-emitting layer 113, and an electron transport layer 114. The hole transport layer 112 consists of the first hole transport layer 112-1 and the second hole transport layer. It is preferable to have layer 112-2, and the electron transport layer 114 is first as shown in Figure 1(A2) It is preferable to have an electron transport layer 114-1 and a second electron transport layer 114-2.

[0033] In addition to these, the EL layer 103 in Figure 1(A1)(A2) also has an electron injection layer 11 Although diagram 5 is shown, the configuration of the light-emitting device is not limited to this. If it has the necessary functionality, it may include layers with other functions.

[0034] The hole injection layer 111 is a layer designed to facilitate the injection of holes into the EL layer 103. It is constructed using high-performance materials. The hole injection layer 111 contains a first substance and a second substance. The first substance possesses hole transport properties, and its HOMO level is below -5.7 eV. The second substance is an organic compound having a relatively deep HOMO level below -5.4 eV. This substance exhibits electron-accepting properties towards the first substance. The first substance has a relatively deep HOMO level. By having this feature, the induction of holes is moderately suppressed, and the transport of the induced holes is also controlled. Injection into layer 112 becomes easier. By configuring the hole injection layer 111 in this way, the drive In the early stages, light-emitting devices in which the carrier recombination region extended not only to the light-emitting layer but also to the electron transport layer. It is possible to produce this.

[0035] The second substance can be either an inorganic or organic compound, but it exhibits electron-withdrawing properties. Use organic compounds that have groups (especially halogen groups such as fluoro groups or cyano groups). This is preferable. As the second substance, from among such substances, an electric charge is applied to the first substance. A suitable substance exhibiting receptivity can be selected as appropriate. Examples of such preferred organic compounds include: For example, 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane ( Abbreviation: F4-TCNQ), Chloranil, 2,3,6,7,10,11-Hexacyano-1 ,4,5,8,9,12-Hexaazatriphenylene (abbreviation: HAT-CN), 1,3, 4,5,7,8-Hexafluorotetracyano-naphthoquinodimethane (abbreviation: F6-TC) NNQ), 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octaf) Examples include ruoro-7H-pyrene-2-ylidene)malononitrile, etc. In particular, A compound in which an electron-withdrawing group is bonded to a condensed aromatic ring containing multiple complex atoms, such as HAT-CN. The substance is preferably thermally stable. Also, electron-withdrawing groups (especially halogen groups such as fluorogroups) are desirable. Radialene derivatives having a group (or cyano group) [3] are preferred because they have very high electron-accepting properties. Specifically, α,α',α''-1,2,3-cyclopropanetriylidentris[4 -Cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α',α' '-1,2,3-cyclopropanetriylidentris[2,6-dichloro-3,5-diph [Luoro-4-(trifluoromethyl)benzeneacetonitrile], α,α',α''-1 ,2,3-cyclopropanetriylidenotris[2,3,4,5,6-pentafluorobe Examples include [synthene acetonitrile]. When the second substance is an inorganic compound, transition metal Gold oxides can be used. In particular, gold belonging to groups 4 through 8 of the periodic table. Oxides of the group are preferred, and the oxides of metals belonging to groups 4 to 8 of the periodic table are preferred. The materials include vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, and molybdenum oxide. Tungsten oxide, manganese oxide, and rhenium oxide are preferred due to their high electron-accepting properties. Among them, molybdenum oxide is preferred because it is stable in the atmosphere, has low hygroscopicity, and is easy to handle. It's nice.

[0036] The first substance is preferably an organic compound having hole-transporting properties, and has a carbazole skeleton. It has one of the following skeletons: dibenzofuran, dibenzothiophene, or anthracene. It is more preferable that it contains a dibenzofuran ring or a dibenzothiophene ring. Aromatic amines having substituents and aromatic monoamines having a naphthalene ring are preferred, Furthermore, an aromatic monoamine in which a 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group. N is also preferable. Furthermore, these first substances have an N,N-bis(4-biphenyl)amino group. It is preferable to use a material that possesses this property because it allows for the creation of light-emitting devices with a good lifespan. Specifically, the first substance described above is N-(4-biphenyl)-6,N-diphenyl Enylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BnfABP), N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]fura n-8-amine (abbreviation: BBABnf), 4,4'-bis(6-phenylbenzo[b]na Futo[1,2-d]furan-8-yl-4''-phenyltriphenylamine (abbreviation: B nfBB1BP), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d] Furan-6-amine (abbreviation: BBABnf(6)), N,N-bis(4-biphenyl) Nzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf(8)), N ,N-bis(4-biphenyl)benzo[b]naphtho[2,3-d]furan-4-amine( Abbreviation: BBABnf(II)(4)), N,N-bis[4-(dibenzofuran-4-yl) )phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP), N-[4- (Dibenzothiophen-4-yl)phenyl]-N-phenyl-4-biphenylamine ( Abbreviation: ThBA1BP), 4-(2-naphthyl)-4',4''-diphenyltriphenyl Luamine (abbreviation: BBAβNB), 4-[4-(2-naphthyl)phenyl]-4',4' '-diphenyltriphenylamine (abbreviation: BBAβNBi), 4,4'-diphenyl- 4''-(6;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβ) NB), 4,4'-diphenyl-4''-(7;1'-binaphthyl-2-yl)triphen Nylamine (abbreviation: BBAαNβNB-03), 4,4'-diphenyl-4''-(7- Phenyl)naphthyl-2-yltriphenylamine (abbreviation: BBAPβNB-03), 4 ,4'-diphenyl-4''-(6;2'-binaphthyl-2-yl)triphenylamine (Abbreviation: BBA(βN2)B), 4,4'-diphenyl-4''-(7;2'-binaphthyl (Lu-2-yl)triphenylamine (abbreviation: BBA(βN2)B-03), 4,4'-di Phenyl-4''-(4;2'-binaphthyl-1-yl)triphenylamine (abbreviation: B BAβNαNB), 4,4'-diphenyl-4''-(5;2'-binaphthyl-1-yl) ) Triphenylamine (abbreviation: BBAβNαNB-02), 4-(4-biphenylyl)- 4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: TPBiAβN) B) 4-(3-biphenylyl)-4'-[4-(2-naphthyl)phenyl]-4''- Phenyltriphenylamine (abbreviation: mTPBiAβNBi), 4-(4-biphenylyl) )-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine( Abbreviation: TPBiAβNBi), 4-phenyl-4'-(1-naphthyl)triphenylamine (abbreviation: αNBA1BP), 4,4'-bis(1-naphthyl)triphenylamine (abbreviation) Name: αNBB1BP), 4,4'-diphenyl-4''-[4'-(carbazole-9- [YGTBi1BP] (Yg)- [4-(3-phenyl-9H-carbazole-9-yl)phenyl]tris(1,1'- Biphenyl-4-yl)amine (abbreviation: YGTBi1BP-02), 4-diphenyl-4 '-(2-naphthyl)-4''-{9-(4-biphenylyl)carbazole)}tripe Nylamine (abbreviation: YGTBiβNB), N-[4-(9-phenyl-9H-carbazo [Lu-3-yl)phenyl]-N-[4-(1-naphthyl)phenyl]-9,9'-spiron Bi(9H-fluorene)-2-amine (abbreviation: PCBNBSF), N,N-bis(4-bi Phenylyl)-9,9'-Spirobi[9H-Fluorene]-2-amine (Abbreviation: BBAS) F), N,N-bis(1,1'-biphenyl-4-yl)-9,9'-spirobio[9H- Fluorene-4-amine (abbreviation: BBASF(4)), N-(1,1'-biphenyl- 2-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spi Robi(9H-fluorene)-4-amine (abbreviation: oFBiSF), N-(4-biphenyl )-N-(dibenzofuran-4-yl)-9,9-dimethyl-9H-fluorene-2-a Min (abbreviation: FrBiF), N-[4-(1-naphthyl)phenyl]-N-[3-(6- Phenyldibenzofuran-4-yl)phenyl]-1-naphthylamine (abbreviation: mPDB) fBNBN), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenyl Luamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenylfluorene-9) -yl)triphenylamine (abbreviation: mBPAFLP), 4-phenyl-4'-[4-( 9-phenylfluoren-9-yl)phenyl]triphenylamine (abbreviation: BPAFL) Bi), 4-phenyl-4'-(9-phenyl-9H-carbazole-3-yl) truffle Phenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl Lu-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazole-3-yl)trif Phenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9- Phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBNBB) N-phenyl-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl ]Spiro-9,9'-bifluoren-2-amine (abbreviation: PCBASF), N-(1,1 '-biphenyl-4-yl)-9,9-dimethyl-N-[4-(9-phenyl-9H-ka Luvazole-3-yl)phenyl]-9H-fluoren-2-amine (abbreviation: PCBBi) Examples include F).

[0037] The composition of the first substance and the second substance in the hole injection layer 111 is 1:0.01 to 1:0 It is preferable that the ratio is 0.15 (by weight). More preferably, it is 1:0.01 to 1:0 It is 0.1 (by weight).

[0038] The hole transport layer 112 may be a single layer, but the first hole transport layer 112-1 and the second hole transport layer It is preferable to have a transport layer 112-2. The first hole transport layer 112-1 is a second hole transport layer It is assumed to be located on the anode 101 side of layer 112-2. -2 may also simultaneously perform the function of the electronic block layer.

[0039] The first hole transport layer 112-1 and the second hole transport layer 112-2 are hole-transporting organic compounds It possesses a substance. The hole-transporting organic compound is used as the first substance mentioned above. Organic compounds capable of this can be used in the same way. The hole-transporting organic compound in the second hole transport layer 112-2 is the same organic compound. However, these may be different organic compounds. Also, the positive properties of the first hole transport layer 112-1 The pore-transporting organic compound and the first substance in the hole injection layer 111 were the same organic compound. However, they may be different organic compounds.

[0040] The HOMO level of the first substance contained in the hole injection layer 111 and the first hole transport layer 112-1 The HOMO level of hole-transporting organic compounds contained in the latter is deeper, and the difference is 0. It is preferable to select materials so that the voltage is 0.2 eV or less.

[0041] Furthermore, the HOMO levels of the hole-transporting organic compounds contained in the first hole transport layer 112-1 and In the HOMO levels of hole-transporting organic compounds contained in the second hole transport layer 112-2, The latter is preferable if it is deeper. Furthermore, select materials so that the difference is 0.2 eV or less. It is good to select. Hole transport properties contained in the second hole transport layer 112-2 from the hole injection layer 111. The HOMO levels of the organic compounds have the above-described relationship, which allows for smooth transitions between layers. This allows for the injection of holes, preventing an increase in the driving voltage and a shortage of holes in the light-emitting layer.

[0042] Note that the first substance contained in the hole injection layer 111, the hole transport layer 112 (the first hole transport layer 1 The hole-transporting organic compounds contained in 12-1 and the second hole transport layer 112-2) are each It is preferable to have a hole-transporting skeleton. As for the hole-transporting skeleton, these organic compounds Carbazole skeleton, dibenzofuran skeleton, diben Zothiophene skeletons and anthracene skeletons are preferred. Furthermore, these hole-transporting skeletons are adjacent to each other. It is preferable if the materials contained in the intersecting layers are common, as this facilitates smoother hole injection. In particular, a dibenzofuran skeleton is preferred as the hole-transporting skeleton.

[0043] Furthermore, if the materials contained in adjacent layers are the same organic compound, hole injection becomes smoother. This is preferable. In particular, the first substance contained in the hole injection layer 111 and the first hole transport layer 11 A configuration in which the hole-transporting organic compound included in 2-1 is made of the same material is preferred.

[0044] The light-emitting layer 113 has a light-emitting substance and a host material. It is acceptable for the materials to be included simultaneously. Furthermore, it is also acceptable for it to be a laminate of two layers with different compositions.

[0045] Whether the luminescent material is a fluorescent material or a phosphorescent material, it exhibits thermally activated delayed fluorescence (T The substance may be any other luminescent substance, even if it exhibits ADF (Active Deposition Factor). One embodiment is a layer that exhibits fluorescence emission, particularly a layer that exhibits blue fluorescence emission. It can be suitably applied depending on the circumstances.

[0046] In the light-emitting layer 113, possible materials that can be used as fluorescent light-emitting materials include, for example, Examples include those listed below. Other fluorescent materials can also be used.

[0047] 5,6-Bis[4-(10-phenyl-9-antryl)phenyl]-2,2'-bipyri Zin (abbreviation: PAP2BPy), 5,6-bis[4'-(10-phenyl-9-antri [Lu)biphenyl-4-yl]-2,2'-bipyridine (abbreviation: PAPP2BPy), N, N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl] )phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-bi Su(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluorene- 9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn) ), N,N'-bis[4-(9H-carbazole-9-yl)phenyl]-N,N'-di Phenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-carbazo (Abbreviated) 4'-(10-phenyl-9-anthryl)triphenylamine ( Name: YGAPA), 4-(9H-carbazole-9-yl)-4'-(9,10-dife Nyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-diphenyl Nyl-N-[4-(10-phenyl-9-antryl)phenyl]-9H-carbazole -3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetra-tert- Butylperylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)-4'-( 9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBAP) A) N,N''-(2-tert-butylanthracene-9,10-diyldi-4,1 -phenylene)bis[N,N',N'-triphenyl-1,4-phenylenediamine]( Abbreviation: DPABPA), N,9-diphenyl-N-[4-(9,10-diphenyl-2- Anthryl)phenyl]-9H-carbazole-3-amine (abbreviation: 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-to Riphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), N,N,N',N ',N'',N'',N''',N'''-Octaphenyldibenzo[g,p]chrysene -2,7,10,15-tetraamine (abbreviation: DBC1), coumarin 30, N-(9,1 0-Diphenyl-2-anthryl)-N,9-Diphenyl-9H-carbazole-3-A Min (abbreviation: 2PCAPA), N-[9,10-bis(1,1'-biphenyl-2-yl] )-2-anthryl]-N,9-diphenyl-9H-carbazole-3-amine (abbreviation: 2PCABPhA), N-(9,10-diphenyl-2-anthryl)-N,N',N' -Triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10 -Bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,N',N'-tri Phenyl-1,4-phenylenediamine (abbreviation: 2DPABPhA), 9,10-bis( 1,1'-biphenyl-2-yl)-N-[4-(9H-carbazole-9-yl) [Nyl]-N-phenylanthracene-2-amine (abbreviation: 2YGABPhA), N,N, 9-Triphenylanthracene-9-amine (abbreviation: DPhAPhA), Coumarin 545 T,N,N'-diphenylquinacridone (abbreviation: DPQd), rubren, 5,12-bis (1,1'-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT) ), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl-4 H-pyran-4-ylidene)propanedinitrile (abbreviation: DCM1), 2-{2-methyl -6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolidine] [-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: D CM2), N,N,N',N'-Tetrakis(4-methylphenyl)tetracene-5,1 1-Diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N',N'- Tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluorantene-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] [Quinoridine-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (Abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7 Tramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolidine 9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DC JTB), 2-(2,6-bis{2-[4-(dimethylamino)phenyl]ethenyl}- 4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDCM), 2-{2, 6-Bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-teto Lahydro-1H,5H-benzo[ij]quinoridine-9-yl)ethenyl]-4H-pyra N-4-ylidene propanedinitrile (abbreviation: BisDCJ™), N,N'-diphosphate Nyl-N,N'-(1,6-pyrene-diyl)bis[(6-phenylbenzo[b]naphthate [1,2-d]furan)-8-amine](abbreviation: 1,6BnfAPrn-03), 3,1 0-Bis[N-(9-phenyl-9H-carbazol-2-yl)-N-phenylamino ]Naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10PCA2Nb f(IV)-02), 3,10-bis[N-(dibenzofuran-3-yl)-N-phenyl Luamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10Fr Examples include A2Nbf(IV)-02). In particular, 1,6FLPAPrn and 1,6m Pyridine compounds such as MemFLPAPrn and 1,6BnfAPrn-03 can be substituted. The condensed aromatic diamine compounds shown exhibit high hole-trapping properties and excellent luminescence efficiency and reliability. This is preferable because it is well-maintained.

[0048] In the light-emitting layer 113, if a phosphorescent material is used as the light-emitting material, it is possible to use it. Examples of suitable materials include the following:

[0049] Tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H -1,2,4-triazole-3-yl-κN2]phenyl-κC}iridium(III ) (abbreviation: [Ir(mpptz-dmp)3]), Tris(5-methyl-3,4-diphen) Iridium(III) (abbreviation: [Ir(Mpt) z)3]), Tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H -1,2,4-Triazolat] Iridium(III) (Abbreviation: [Ir(iPrptz-3 Organometallic iridium complexes having a 4H-triazole skeleton, such as b)3]), and Tris [3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-tria Zolato] Iridium (III) (abbreviation: [Ir(Mptz1-mp)3]), Tris (1 -Methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium (III) (Abbreviation: [Ir(Prptz1-Me)3]) 1H-triazole bone iridium organometallic complexes with a specific classification, and fac-tris[(1-2,6-diisopropyl [Phenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviation: [Ir (iPrpmi)3]), Tris[3-(2,6-dimethylphenyl)-7-methylimi Dazo[1,2-f]phenantriginato]iridium(III) (abbreviation:[Ir(dmp Organometallic iridium complexes having an imidazole skeleton such as impt-Me)3]), Bis[2-(4',6'-difluorophenyl)pyridinate-N,C 2’ ]iridium( III) Tetrakis(1-pyrazolyl)borate (abbreviation: Fir6), bis[2-(4' ,6'-Difluorophenyl)pyridinate-N,C 2’ Iridium(III) picolina Firpic (abbreviation: Firpic), bis{2-[3',5'-bis(trifluoromethyl) [enyl]pyridinate-N,C 2’ Iridium(III) picolinate (abbreviation: [Ir( CF3ppy)2(pic)]), bis[2-(4',6'-difluorophenyl)pyri Dinato-N,C 2’ Iridium(III) acetylacetonate (abbreviation: Fir(ac) Organometallic compounds using phenylpyridine derivatives having electron-withdrawing groups like ac)) as ligands Examples include lydium complexes. These are compounds that exhibit blue phosphorescence, at 440 nm. This compound has an emission peak from 520 nm.

[0050] Also, tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)3]), Tris(4-t-butyl-6-phenylpyrimidinato)yli Dium(III) (abbreviation: [Ir(tBuppm)3]), (acetylacetonato)bis (6-methyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mp) pm)2(acac)]), (acetylacetonato)bis(6-tert-butyl-4- Phenylpyrimidina) Iridium(III) (Abbreviation: [Ir(tBuppm)2(ac (ac)), (acetylacetonate)bis[6-(2-norbornyl)-4-phenylp Limiginato Iridium(III) (abbreviation: [Ir(nbppm)2(acac)]), (Acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenyl [Pyrimidinato] Iridium(III) (Abbreviation: [Ir(mpmppm)2(acac)] ), (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(II) I) (abbreviation: [Ir(dppm)2(acac)]) has a pyrimidine skeleton iridium metal complexes and (acetylacetonato)bis(3,5-dimethyl-2-phenyl Iridium(III) (abbreviation: Ir(mppr-Me)2(acac)) ]), (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyra) Dinato-iridium(III) (abbreviation: [Ir(mppr-iPr)2(acac)]) organometallic iridium complexes having a pyrazine skeleton, such as tris(2-phenylpyridium Nato-N,C 2’ ) Iridium(III) (abbreviation: [Ir(ppy)3]), bis(2- Phenylpyridinato-N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: [Ir(ppy)2(acac)]), bis(benzo[h]quinolinate) iridium (I II) Acetylacetonate (abbreviation: [Ir(bzq)2(acac)]), Tris(be Iridium (III) (abbreviation: [Ir(bzq)3]), Tris (2-phenylquinolinato-N,C 2’ Iridium(III) (abbreviation: [Ir(pq) 3]), bis(2-phenylquinolinato-N,C 2’ Iridium(III) acetylated Setanate (abbreviation: [Ir(pq)2(acac)]) is a pyridine skeleton-containing substance In addition to iridium metal complexes, tris(acetylacetonate)(monophenanthroline) Rare earth metals such as rubium(III) (abbreviation: [Tb(acac)3(Phen)]) Examples include complexes. These are compounds that mainly exhibit green phosphorescence, with a wavelength of 500 nm to 6 It has an emission peak at 00 nm. Furthermore, it is an organometallic iridium complex with a pyrimidine skeleton. The body is particularly preferable because it is outstanding in terms of reliability and luminescence efficiency.

[0051] Also, (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimid Sodium iridium(III) (abbreviation: [Ir(5mdppm)2(dibm)]), bis(Ir(5mdppm)2(dibm)]), [4,6-Bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridi Um(III) (abbreviation: [Ir(5mdppm)2(dpm)]), bis[4,6-di( Naphthalene-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) Organometallic gold with a pyrimidine skeleton, such as (abbreviation: [Ir(d1npm)2(dpm)]) Iridium complexes of the genus, and (acetylacetonato)bis(2,3,5-triphenylpyrazine Iridium(III) (abbreviation: [Ir(tppr)2(acac)]), bis(2, 3,5-Triphenylpyrazinate)(dipivaloylmethanato) Iridium(III) (abbreviated) Name: [Ir(tppr)2(dpm)]), (acetylacetonato)bis[2,3-bis (4-Fluorophenyl)quinoxalinato] Iridium(III) (Abbreviation: [Ir(Fd Organometallic iridium complexes having a pyrazine skeleton such as pq)2(acac)]) and RIS(1-phenylisoquinolinato-N,C)2’ ) Iridium(III) (abbreviation: [Ir (piq)3]), bis(1-phenylisoquinolinato-N,C 2’ ) Iridium(II I) acetylacetonate (abbreviation: [Ir(piq)2(acac)]) and other organometallic iridium complexes having a pyridine skeleton, as well as platinum complexes such as 2,3,7,8,12,13,17,18 -octaethyl-21H,23H-porphyrin platinum(II) (abbreviation: PtOEP), and rare earth metal complexes such as tris(1,3-diphenyl-1,3-propanedionato)(monophen anthroline) europium(III) (abbreviation: [Eu(DBM)3(Phen)]), tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthro line) europium(III) (abbreviation: [Eu(TTA)3(Phen)]). These are compounds that exhibit red phosphorescent emission and have an emission peak at 60 0 nm to 700 nm. In addition, organometallic iridium complexes having a pyrazine skeleton can obtain red emission with good chromaticity. 0 nm to 700 nm. In addition, organometallic iridium complexes having a pyrazine skeleton can obtain red emission with good chromaticity. In addition to the above-described phosphorescent compounds, known phosphorescent substances may be selected and used.

[0052] [[ID=OB]] In addition to the above-described phosphorescent compounds, known phosphorescent substances may be selected and used. Yes.

[0053] As the TADF material, fullerenes and their derivatives, acridines and their derivatives, eosin derivatives, etc. can be used. In addition, metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (P d), etc. can be mentioned. Examples of the metal-containing porphyrin include, for example, the protoporphyrin-tin fluoride complex (SnF2(Pro shown in the following structural formula. to IX), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), Hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), copropol Filinetetramethyl ester-tin fluoride complex (SnF2(Copro III-4M) e) Octaethylporphyrin-tin fluoride complex (SnF2(OEP)), ethio Rufirin-tin fluoride complex (SnF2(Etio I)), octaethylporphyrin Examples include platinum chloride complexes (PtCl2OEP), etc.

[0054] [ka]

[0055] Furthermore, the following structural formula shows 2-(biphenyl-4-yl)-4,6-bis(12-) Enylindoro[2,3-a]carbazole-11-yl)-1,3,5-triazine( Abbreviations: PIC-TRZ) and 9-(4,6-diphenyl-1,3,5-triazine-2- Il)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCzT) Zn), 9-[4-(4,6-diphenyl-1,3,5-triazine-2-yl)phenyl [Lu]-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCzPT) Zn), 2-[4-(10H-phenoxazine-10-yl)phenyl]-4,6-diph Phenyl-1,3,5-triazine (abbreviation: PXZ-TRZ), 3-[4-(5-phenyl -5,10-dihydrophenazine-10-yl)phenyl]-4,5-diphenyl-1, 2,4-Triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-) Cryzin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), bis[ 4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), 10-phenyl-10H,10'H-spiro[acridine-9,9 π-electron-rich heteroaromatic rings such as '-anthracene]-10'-one (abbreviated as ACRSA) Heterocyclic compounds having one or both of the π-electron-deficient heteroaromatic rings can also be used. The heterocyclic compound has a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring. It is preferable because it has high electron transport and hole transport properties. In particular, the π-electron-deficient heteroaromatic ring is Among the skeletons it possesses, pyridine skeleton, diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyr The dazine skeleton and the triazine skeleton are preferred because they are stable and reliable. In particular, Benzoflopyrimidine skeleton, benzothienopyrimidine skeleton, benzoflopyrazine skeleton, ben The zothienopyrazine skeleton is preferred because it has high acceptability and good reliability. Also, π Among skeletons having electron-excess heteroaromatic rings, the acridine skeleton, the phenoxazine skeleton, and fu The phenothiazine skeleton, furan skeleton, thiophene skeleton, and pyrrole skeleton are stable and reliable. For the sake of being good, it is preferable to have at least one of the skeletons. The dibenzofuran skeleton is used for the thiophene skeleton, and the dibenzothiophene skeleton is used for the thiophene skeleton, respectively. Preferred. Also, as pyrrole skeletons, indole skeletons, carbazole skeletons, indole Carbazole skeleton, bicarbazole skeleton, 3-(9-phenyl-9H-carbazole-3) The -yl)-9H-carbazole skeleton is particularly preferred. Substances in which electron-deficient heteroaromatic rings are directly bonded to π-electron-rich heteroaromatic rings have electron-donating properties. The electron-accepting ability of π-electron-deficient heteroatomous rings increases, and the energies of the S1 and T1 levels change. This is particularly preferable because the difference becomes smaller, allowing for efficient acquisition of thermally activated delayed fluorescence. Instead of a π-electron-deficient heteroaromatic ring, an aromatic ring with an electron-withdrawing group such as a cyano group attached is used. It may also be used. In addition, aromatic amine skeletons, phenazine skeletons, etc. can be used as π-electron-rich skeletons. It can be used. In addition, xanthene skeletons and thioxanthene skeletons can be used as π-electron-deficient skeletons. Dioxide skeleton, oxadiazole skeleton, triazole skeleton, imidazole skeleton, Traquinone skeleton, boron-containing skeletons such as phenylborane and volanthrene, benzonitrile and These include aromatic rings or heteroaromatic rings having nitrile or cyano groups such as cyanobenzene, and benzobenzene. Carbonyl skeletons such as phenones, phosphine oxide skeletons, sulfone skeletons, etc. can be used. In this way, at least of the π-electron-deficient heteroaromatic ring and the π-electron-excess heteroaromatic ring Instead of one, a π-electron-deficient skeleton and a π-electron-excess skeleton can be used.

[0056] [ka]

[0057] TADF materials are characterized by a small difference between the S1 and T1 levels, and triple intersystem crossing occurs due to reverse intersystem crossing. A function that can convert energy from singlet excitation energy to singlet excitation energy. It is a material that possesses this property. Therefore, the triplet excitation energy is obtained by a small amount of thermal energy. Upconversion to the multiplet excitation energy (reverse intersystem crossing) is possible, and the singlet excited state can be efficiently converted. It can be generated easily. Furthermore, the triplet excitation energy can be converted into luminescence. .

[0058] Furthermore, an excited complex (exciplex) is formed by two different substances forming an excited state. Exciplex (also called 'x' or 'exciplex') is a state where the difference between the S1 level and the T1 level is extremely small. As a TADF material capable of converting triplet excitation energy to singlet excitation energy, It has the function of being functional.

[0059] Furthermore, the phosphorescence spectrum observed at low temperatures (e.g., 77K to 10K) can be used as an indicator of the T1 level. A cull can be used. As for TADF materials, the short-wavelength tail of its fluorescence spectrum is Draw a tangent line, and set the energy at the wavelength of the extrapolation line as the S1 level, and the short wave of the phosphorescence spectrum When a tangent line is drawn at the long side of the tail, and the energy of the wavelength of the extrapolation line is taken as the T1 level, Preferably, the difference between S1 and T1 is 0.3 eV or less, and preferably 0.2 eV or less. Even better.

[0060] Furthermore, when using TADF material as a light-emitting material, the S1 level of the host material is the TADF material. It is preferable that the T1 level of the host material is higher than the S1 level of the TADF material. A higher rank is preferable.

[0061] The host material for the light-emitting layer may be an electron-transporting material or a hole-transporting material, or the above Various carrier transport materials, such as TADF materials, can be used.

[0062] Materials with hole transport properties include those having an amine skeleton or a π-electron-rich heteroaromatic ring skeleton. A compound is preferred. For example, 4,4'-bis[N-(1-naphthyl)-N-phenyl Mino]biphenyl (abbreviation: NPB), N,N'-bis(3-methylphenyl)-N,N' -diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4, 4'-Bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenylamino ] Biphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluorene-9) -yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenyl) Nylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-phenyl Lu-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviated name) :PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazo (3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl )-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation) :PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-ka Luvazole-3-yl)triphenylamine (abbreviation: PCBNBB), 9,9-dimethyl -N-phenyl-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl] Fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl Nyl-9H-carbazole-3-yl)phenyl]spiro-9,9'-bifluoren-2 Compounds having an aromatic amine skeleton such as -amine (abbreviation: PCBASF), and 1,3- Su(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazolyl) Biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenyl Nilcarbazole (abbreviation: CzTP), 3,3'-bis(9-phenyl-9H-carbazo Compounds having a carbazole skeleton, such as (PCCP) (abbreviation: PCCP), and 4,4',4'' -(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P) -II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluorene-9-i [Phenyl]dibenzothiophene (abbreviation: DBTFLP-III), 4-[4-(9- Phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene Compounds with a thiophene skeleton, such as (abbreviation: DBTFLP-IV), and 4,4',4' '-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P- II) 4-{3-[3-(9-phenyl-9H-fluorene-9-yl)phenyl] }Dibenzofuran (abbreviation: mmDBFFLBi-II) and other furan skeletons Examples include compounds. Among those mentioned above, compounds having an aromatic amine skeleton and carbazoles are examples. Compounds with a skeletal structure offer good reliability, high hole transport properties, and reduced driving voltage. This is also preferable as it contributes to the process. Furthermore, the organic compounds listed above as examples of the first substance can also be used. It is possible.

[0063] Examples of materials with electron transport properties include bis(10-hydroxybenzo[h]quinoli Sodium beryllium(II) (abbreviation: BeBq2), bis(2-methyl-8-quinolinolate) )(4-phenylphenolate)aluminum(III) (abbreviation: BAlq), bis(8- Zinc(II) (abbreviation: Znq), bis[2-(2-benzoxazolyl) [Phenolate]zinc(II) (abbreviation: ZnPBO), bis[2-(2-benzothiazolyl) Metal complexes such as phenolate zinc(II) (abbreviated as ZnBTZ) and π-electron-deficient heteroatoms Organic compounds having a fragrant ring skeleton are preferred. Organic compounds having a π-electron-deficient hetero-aromatic ring skeleton. For example, 2-(4-biphenylyl)-5-(4-tert-butylphenyl )-1,3,4-Oxadiazole (abbreviation: PBD), 3-(4-biphenylyl)-4- Phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxa [Diazole-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1] ,3,4-Oxadiazole-2-yl)phenyl]-9H-carbazole (abbreviation: CO 11) 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl- 1H-Benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophene-4) -yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm Heterocyclic compounds having a polyazole skeleton such as -II), and 2-[3-(dibenzothioff) [phenyl-4-yl]phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDB) q-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]di Benzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-( 9H-carbazole-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxali n (abbreviation: 2mCzBPDBq), 4,6-bis[3-(phenanthrene-9-yl)f [enyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-diben Dia, such as zothienyl(phenyl)pyrimidine (abbreviation: 4,6mDBTP2Pm-II) Heterocyclic compounds having a din skeleton, and 2-[3'-(9,9-dimethyl-9H-fluorene -2-yl)-1,1'-biphenyl-3-yl]-4,6-diphenyl-1,3,5- Triazine (abbreviation: mFBPTzn), 2-[(1,1'-biphenyl)-4-yl]- 4-phenyl-6-[9,9'-spirobio(9H-fluorene)-2-yl]-1,3, 5-triazine (abbreviation: BP-SFTzn), 2-{3-[3-(benzo"b"naphtho[ 1,2-d]furan-8-yl)phenyl]phenyl}-4,6-diphenyl-1,3, 5-triazine (abbreviation: mBnfBPTzn), 2-{3-[3-(benzo"b"naphthol [1,2-d]furan-6-yl)phenyl]phenyl}-4,6-diphenyl-1,3 ,5-triazine (abbreviation: mBnfBPTzn-02), and other triazine skeletons Heterocyclic compounds and 3,5-bis[3-(9H-carbazole-9-yl)phenyl]pyri Zin (abbreviation: 35DCzPPy), 1,3,5-tri[3-(3-pyridyl)phenyl] Examples include heterocyclic compounds having a pyridine skeleton, such as benzene (abbreviated as TmPyPB). Among those mentioned above, heterocyclic compounds having a diazine skeleton and heterocyclic compounds having a triazine skeleton Compounds, heterocyclic compounds having a pyridine skeleton, are reliable and preferred. In particular, di Heterocyclic compounds having an azine (pyrimidine or pyrazine) skeleton and triazine skeletons. These heterocyclic compounds exhibit high electron transport properties and contribute to reducing the driving voltage.

[0064] As for TADF materials that can be used as host materials, the previously mentioned TADF materials are... The same material can be used. When TADF material is used as the host material, TA The triplet excitation energy generated in the DF material is converted to a singlet excitation energy through reverse intersystem crossing. It is converted into a substance, and then energy is transferred to the light-emitting material, thereby increasing the luminescence efficiency of the light-emitting device. This can be achieved. At this time, the TADF material functions as an energy donor, and the luminescent substance It functions as an energy acceptor.

[0065] This is very effective when the above-mentioned light-emitting material is a fluorescent material. In order to obtain high luminescence efficiency, the S1 level of the TADF material is higher than the S1 level of the fluorescent material. It is preferable that the T1 level of the TADF material is higher than the S1 level of the fluorescent material. A high level is preferable. Therefore, the T1 level of the TADF material is the same as the T1 level of the fluorescent material. A higher value is preferable.

[0066] Furthermore, T exhibits emission that overlaps with the wavelength of the lowest energy absorption band of the fluorescent material. It is preferable to use ADF material. This allows the fluorescent material to be converted from TADF material. This is preferable because it allows for smoother transfer of excitation energy and efficient emission.

[0067] Furthermore, singlet excitation energy is efficiently generated from triplet excitation energy through reverse intersystem crossing. For this to occur, it is preferable that carrier recombination occurs in the TADF material. The triplet excitation energy generated by the DF material is transferred to the triplet excitation energy of the fluorescent material. It is preferable not to do so. To that end, the fluorescent material has a luminescent phosphodiolus ( It is preferable to have a protecting group around the skeleton that causes light emission. The protecting group is a π bond. Substituents that do not have a substituent are preferred, saturated hydrocarbons are preferred, specifically those having 3 to 10 carbon atoms. The alkyl group below, substituted or unsubstituted cycloalkyl groups with 3 to 10 carbon atoms, carbon Examples include trialkylsilyl groups with a number between 3 and 10, and it is even preferable if there are multiple protecting groups. Substituents that do not have a π bond have poor carrier transport function, therefore carrier transport and The distance between the TADF material and the fluorescent material's luminescent phosphate is minimized without affecting carrier recombination. It can keep the distance away. Here, a luminescent group is the substance that causes light emission in a fluorescent substance. This refers to an atomic group (skeleton). The luminescent group preferably has a skeleton with π bonds and contains an aromatic ring. It is preferable that it has a condensed aromatic ring or a condensed heteroaromatic ring. Examples of compound aromatic rings include the phenanthrene skeleton, stilbene skeleton, acridone skeleton, and pheno Examples include xazine skeletons and phenothiazine skeletons. In particular, naphthalene skeletons and anthracene skeletons. Skeleton, fluorene skeleton, chrysene skeleton, triphenylene skeleton, tetracene skeleton, pyrene skeleton It has a perylene skeleton, coumarin skeleton, quinacridone skeleton, and naphthobisbenzofuran skeleton. Fluorescent materials are preferred because they have a high fluorescence quantum yield.

[0068] When using a fluorescent material as the light-emitting material, the host material should have an anthracene skeleton. Materials that are suitable for this purpose are used as host materials for fluorescent materials. When used in this way, it is possible to realize a light-emitting layer with good luminescence efficiency and durability. Host material Substances having an anthracene skeleton that can be used as a material include diphenylanthracene skeletons, In particular, substances having a 9,10-diphenylanthracene skeleton are preferred because they are chemically stable. Furthermore, if the host material has a carbazole skeleton, hole injection and transport properties are enhanced. Therefore, it is preferable, but a benzocarbazole skeleton in which a benzene ring is further condensed on carbazole is preferable. When included, the HOMO becomes about 0.1 eV shallower than that of carbazole, making it easier for holes to enter. Therefore, it is preferable. In particular, when the host material contains a dibenzocarbazole skeleton, The HOMO becomes about 0.1 eV shallower than in zole, making it easier for holes to enter, and also for hole transport. It is also excellent in terms of properties and has high heat resistance, making it suitable. Therefore, it is even more suitable as a host material. What is interesting is the 9,10-diphenylanthracene skeleton and the carbazole skeleton (or It is a substance that simultaneously possesses a benzocarbazole skeleton or a dibenzocarbazole skeleton. From the viewpoint of hole injection and transport as described above, the carbazole skeleton was replaced with a benzofluorene skeleton. A dibenzofluorene skeleton may also be used. An example of such a substance is 9-phenyl Lu-3-[4-(10-phenyl-9-antryl)phenyl]-9H-carbazole ( Abbreviation: PCzPA), 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H- Carbazole (abbreviation: PCPN), 9-[4-(10-phenyl-9-anthracenyl) Phenyl]-9H-carbazole (abbreviation: CzPA), 7-[4-(10-phenyl-9 -Anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBC) zPA), 6-[3-(9,10-diphenyl-2-anthryl)phenyl]-benzo[ b)Naphtho[1,2-d]furan (abbreviation: 2mBnfPPA), 9-phenyl-10-{ 4-(9-phenyl-9H-fluoren-9-yl)biphenyl-4'-yl}anthra Sen (abbreviation: FLPPA), 9-(1-naphthyl)-10-[4-(2-naphthyl)fe Examples include nylanthracene (abbreviation: αN-βNPAnth). In particular, CzPA, cgDBCzPA, 2mBnfPPA, and PCzPA exhibit very good properties and are therefore preferred. That's a good choice.

[0069] Furthermore, the host material may be a mixture of multiple substances, and the mixed host material When used, a mixture of electron-transporting material and hole-transporting material is used. Preferably, by mixing an electron-transporting material with a hole-transporting material. Furthermore, the transport properties of the light-emitting layer 113 can be easily adjusted, and the recombination region can be easily controlled. This is possible. The weight ratio of the content of hole-transporting material to electron-transporting material is positive. The ratio of materials with pore transport properties to materials with electron transport properties should be 1:19 to 19:1.

[0070] Furthermore, phosphorescent materials can be used as part of the above-mentioned mixed materials. When using a fluorescent material as a light-emitting material, excitation energy is supplied to the fluorescent material. It can be used as an energy donor.

[0071] Furthermore, these mixed materials may form excited complexes. These excited complexes are luminescent substances. It forms an excited complex that emits light that overlaps with the wavelength of the lowest energy absorption band. By selecting the right combination, energy transfer becomes smoother, and luminescence is obtained more efficiently. This is preferable because it allows for a reduction in the drive voltage.

[0072] Furthermore, at least one of the materials forming the excitation complex may be a phosphorescent material. By doing so, the triplet excitation energy is efficiently converted to the singlet excitation energy through reverse intersystem crossing. It can be converted to -.

[0073] As a combination of materials that efficiently form an exciplex, it is preferable that the HO of the material having hole-transporting properties MO level is above the HOMO level of the material having electron-transporting properties. Also, the LUMO level of the material having hole-transporting properties is preferably above the LUMO level of the material having electron-transporting properties. Note that the LUMO level and HOMO level of the material can be derived from the electrochemical properties (reduction potential and oxidation potential) of the material measured by cyclic voltammetry (CV) measurement.

[0074] Note that the formation of the exciplex can be confirmed, for example, by comparing the emission spectra of the material having hole-transporting properties, the emission spectra of the material having electron-transporting properties, and the emission spectra of the mixed film of these materials, and observing the phenomenon that the emission spectrum of the mixed film is shifted to a longer wavelength ( or has a new peak on the longer wavelength side) than the emission spectra of each material. Alternatively, it can be confirmed by comparing the transient photoluminescence (PL) of the material having hole-transporting properties, the transient PL of the material having electron-transporting [[ID=Z2]]properties, and the transient PL of the mixed film of these materials, and observing the difference in transient response such that the transient PL lifetime of the mixed film has a longer lifetime component or the ratio of the delayed component becomes larger than the transient PL lifetimes of each material. Alternatively, it can be confirmed by comparing the transient PL of the material having hole-transporting properties, the transient EL of the material having electron-transporting properties, and the transient EL of the mixed film of these materials, and observing the difference in transient response. Also, the above transient PL can be read as transient electroluminescence (EL). That is, it can also be confirmed by comparing the transient EL of the material having hole-transporting properties, the transient EL of the material having electron-transporting properties, and the transient EL of the mixed film of these materials, and observing the difference in transient response.

[0075] In the light-emitting device according to one aspect of the present invention, the electron transport layer 114 resists by flowing a current It is constructed from materials that have a low resistance value. The electron transport layer 114 is subjected to resistance by passing an electric current through it. By constructing it with materials that have a low resistance, it becomes possible to conduct electric current, i.e., to drive a light-emitting device. This allows us to create a light-emitting device in which the resistance of the electron transport layer 114 decreases. Here, in the initial stages of operation, the carrier recombination region is not only in the light-emitting layer, but also in the electron transport If you design a light-emitting device that extends to the transmission layer, as the operating time progresses, electrons As the transportability of the transport layer 114 increases, the carrier balance changes, and the cathode side of the recombination region This makes it possible to obtain a light-emitting device that undergoes a change in which the edges move towards the light-emitting layer 113. Because the energy of carriers recombined in the electron transport layer 114 is hardly converted into light, The recombination region, which had extended to the electron transport layer 114, is pushed back towards the light-emitting layer 113. Therefore, the loss of recombination energy can be reduced. As a result, by driving it... A light-emitting device can be obtained that exhibits increased luminous efficiency and brightness. Light-emitting devices can overcome the rapid degradation that occurs during the initial stages of operation, known as initial degradation, by increasing their brightness. This allows for offsetting, resulting in less initial degradation and, consequently, a very good operating life. This makes it possible to create a light-emitting device. Such a light-emitting device is called Recomb Site Tailoring Injection Element (ReSTI Let us refer to it as an element.

[0076] Furthermore, in the initial stages of operation, the carrier recombination region extends not only to the light-emitting layer but also to the electron transport layer. To fabricate an optical device, the hole injection layer 111 is made to have hole transport properties and its HOMO The first substance has a relatively deep HOMO level between -5.7 eV and -5.4 eV. The material can be formed by including a first material and a second material that exhibits electron-accepting properties. .

[0077] Materials whose resistance decreases when an electric current is passed through them include alkali metals or alkalis. Materials containing organometallic complexes of earth metals are preferred. These materials include alkali metals or aluminum alloys. Even if formed solely from organometallic complexes of potassium earth metals, alkali metals or alkaline earth metals It may be composed of metal organometallic complexes and other substances. By passing an electric current through it, resistance Materials that reduce the resistance value include those other than organometallic complexes of alkali metals or alkaline earth metals. If a substance is present, an organic compound having electron transport properties is preferred as the substance. .

[0078] Furthermore, alkali metals or alkalis are used in materials whose resistance decreases when an electric current is passed through them. If an organometallic complex of an earth metal is present, the alkali metal or alkaline earth metal The organometallic complex is preferably a complex that forms clusters when an electric current flows through it. The formation of clusters in the complex increases electron transportability, and the resistance value of the electron transport layer 114 It becomes possible to obtain a light-emitting device with reduced performance.

[0079] In particular, organometallic complexes of alkali metals or alkaline earth metals and organic compounds with electron transport properties If the material contains a compound, the complex forms clusters when an electric current is passed through it. When they gather together, organic compounds with electron-transporting properties inevitably move in a direction that brings them closer together. This widens the conductive paths between organic compounds that possess electron-transporting properties, thus increasing electron transport. By increasing the electron transport property of layer 114, a light-emitting device with a reduced resistance value of the electron transport layer 114 can be obtained.

[0080] The organic compound having such electron transport property is an organic compound with dominant electron transport property over hole transport property, and its electron mobility is 1 ×10 ×10 -7 cm 2 / Vs or more and 5×10 -5 cm 2 / Vs or less, which is preferable. By having the electron mobility in the electron transport layer within the above range, the injection amount of electrons into the light-emitting layer can be controlled, and the light-emitting layer can be prevented from being in a state of excessive electrons.

[0081] In addition, the organic compound having such electron transport property preferably has its HOMO level of -6.0 eV or more. Further, the organic compound having electron transport property is preferably an organic compound having an anthracene skeleton, and more preferably an organic compound containing both an anthracene skeleton and a heterocyclic skeleton. As the heterocyclic skeleton, a nitrogen-containing 5-membered ring skeleton is preferable, and as the nitrogen-containing 5-membered ring skeleton, it is particularly preferable to have a nitrogen-containing 5-membered ring skeleton containing two heteroatoms in the ring, such as a pyrazole ring, an imidazole ring, an oxazole ring, and a thiazole ring.

[0082] The organometallic complex of an alkali metal or an alkaline earth metal is preferably a metal complex having a ligand containing nitrogen and oxygen, and an alkali metal or an alkaline earth metal. In particular, the organometallic complex of an alkali metal or an alkaline earth metal has an 8-hydroxyquinolinate structure. ​Preferably, it is a metal complex having a ligand containing a compound and a monovalent metal ion, and 8-Hyd It is even more preferable that the lithium complex has a ligand containing a roxyquinolinat structure. Specifically, 8-hydroxyquinolinatolithium (abbreviation: Liq), 8-hydroxy Examples include sodium nolinato (abbreviated as Naq). Among them, 8-hydro Lithium xikinolinato (abbreviated as Liq) is preferred.

[0083] Furthermore, the electron transport layer 114 is composed of an organic compound having electron transport properties in its thickness direction and aluminum There may be parts where the mixing ratio of potash metals or alkaline earth metal organometallic complexes differs. i. The mixing ratio is for an organometallic complex of alkali metal or alkaline earth metal on the cathode side. A small mixing ratio is preferable, and regarding the magnitude of the mixing ratio, time-of-flight type secondary ions Mass spectrometry (ToF-SIMS: Time-of-flight secondary i Inferred from the amount of atoms or molecules detected (on mass spectrometry). It is possible. In parts with different mixing ratios composed of the same two types of materials, ToF - The magnitude of the values ​​detected by SIMS analysis indicates the relative strength of the atoms, molecules, or ions of interest. This corresponds to the magnitude of the abundance. Therefore, organic compounds and alkali metals that possess electron transport properties. Alternatively, by comparing the amount of substances detected that originate from organometallic complexes of alkaline earth metals This also makes it possible to estimate the relative sizes of the mixing ratios.

[0084] In other words, the electron transport layer 114 consists of a first electron transport layer 114-1 and a second electron transport layer 11 4-2 exists, the first electron transport layer is located on the anode side than the second electron transport layer, and the first electron The concentration of alkali metal or alkaline earth metal organometallic complexes in the secondary transport layer and the second electron transport It is preferable that the concentrations of alkali metal or alkaline earth metal organometallic complexes in the layers differ. Furthermore, the concentration of alkali metal or alkaline earth metal organometallic complexes is determined by the second electron transport layer. Having a denser first electron transport layer is preferable because it allows for the creation of longer-lasting devices. It seems so.

[0085] Furthermore, the electron transport layer 114 contains an electron transportable organic compound and an alkali metal or The relative abundance of alkaline earth metals with organometallic complexes is clearly defined as distinct layers, as shown in Figure 1(A1). If there is no boundary, it may change continuously as shown in Figure 32(A1)(A2), or Figure If it can be seen that it is separated into layers as in 1(A2), see Figure 32(B1)(B2). It may change in a step-like manner as shown. Furthermore, the electron transport properties in the electron transport layer 114 Rather than the region with low concentrations of alkali metal or alkaline earth metal organometallic complexes that are rate-determining Regions with high concentrations of alkali metal or alkaline earth metal organometallic complexes on the light-emitting layer 113 side In other words, in the electron transport layer 114, from the cathode side toward the anode side The abundance (concentration) of organometallic complexes of alkali metals or alkaline earth metals is increasing. A region exists, or alkali metals or alkaline earth metals are present in the electron transport layer 114. The region with the highest abundance (concentration) of the organometallic complex of the genus is closer to the anode than the region with the lowest abundance. It is preferable that it be present.

[0086] The electron-transporting organic compound included in the electron transport layer 114 is the same as the host material used above. An organic compound having electron transport properties that can perform this function, or a host material for the above-mentioned fluorescent material. The organic compounds listed as usable in this context can be used.

[0087] Furthermore, the average electric field strength [V / cm] of the electron-transporting organic compound contained in the electron transport layer 114 The electron mobility at a root of 600 is smaller than that of the host material or the light-emitting layer 113. It is preferable.

[0088] When the light-emitting layer becomes electron-rich, the recombination region 113-1 becomes as shown in Figure 2(A). By limiting the treatment to a specific area, the burden on that area increases, accelerating its deterioration. Furthermore, if electrons pass through the light-emitting layer without being able to recombine, the lifetime and luminous efficiency will decrease. In one aspect of the present invention, by reducing the electron transportability in the electron transport layer 114, Figure 2 (B) The recombination region 113-1 is expanded, and the burden on the material constituting the light-emitting layer 113 is distributed. By dispersing the light, it is possible to provide a light-emitting device with a long lifespan and good luminous efficiency.

[0089] Furthermore, in a light-emitting device having such a configuration, a drive test under conditions of constant current density is performed. In the luminance degradation curve obtained by this method, there are cases where a shape with a maximum value is observed. Furthermore, the degradation curve of a light-emitting device according to one aspect of the present invention shows that the brightness increases over time. It may take on a shape that has parts. Light-emitting devices that exhibit such degradation behavior are what are called This can be offset by the increase in brightness, which is the rapid degradation that occurs during the initial stages of operation, known as initial degradation. This results in a light-emitting device with minimal initial degradation and a very good operating life. This becomes possible. Such light-emitting devices are called Recombination-Site T This will be referred to as an ailoring injection element (ReSTI element).

[0090] Furthermore, if we take the derivative of a degradation curve that has such a maximum value, there will be a region where the value is zero. Therefore, in one embodiment of the present invention, there is a portion in the derivative of the degradation curve that is zero. Optical devices exhibit low initial degradation and are light-emitting devices with a very good lifespan. Cut.

[0091] The behavior of the degradation curve described above is as shown in Figure 3(A), where electron transport occurs in the initial stages of operation. Due to low electron mobility in the layer, recombination that does not contribute to luminescence is called the non-luminescent recombination region. This phenomenon is thought to be caused by something that occurs at 120. In other words, this book has the above configuration. In the light-emitting device of the invention, the hole injection barrier is small in the initial stages of operation (HOMO of the first material). Due to the deep energy levels and the relatively low electron transportability of the electron transport layer 114, reconnection The combined region 113-1 is formed in a state that extends from the light-emitting layer 113 to the electron transport layer 114. Furthermore, the HOMO level of the electron-transporting organic compound contained in the electron transport layer 114 is -6 If the voltage is relatively high, above 0.0 eV, then H of the organometallic complex of alkali metals or alkaline earth metals... Since the OMO levels are in similar positions, holes can more easily reach the electron transport layer 114. Recombination also occurs in the electron transport layer 114, making it easier for the non-luminescent recombination region 120 to form.

[0092] Here, in the light-emitting device according to one aspect of the present invention, as the operating time elapses, the carrier As the balance changes, the cathode-side end of the recombination region 113-1 undergoes hole transport, as shown in Figure 3(B). It moves towards layer 112. As a result, the non-luminescent recombination region 120 decreases, and recombination occurs. This makes it possible to effectively contribute the combined carrier energy to light emission, compared to the initial stage of operation. Compared to this, an increase in brightness occurs. This increase in brightness is the rapid increase in brightness that appears at the initial stage of operation of the light-emitting device. By offsetting the decrease in performance, or so-called initial degradation, the light-emitting diode exhibits less initial degradation and a longer operating life. This makes it possible to provide vices.

[0093] Here, the present inventors state that the change in carrier balance in a light-emitting device according to one embodiment of the present invention is , brought about by a change in the resistance of the light-emitting device, particularly a change in the resistance of the electron transport layer 114. This was verified experimentally. Changes in resistance were measured using impedance spectroscopy (IS). It was measured by [method / method].

[0094] In impedance spectroscopy measurements, a small sinusoidal voltage signal [V=V Apply 0exp(iωt) and the response current signal [I=I0exp{i(ωt+φ)} The impedance (Z=V / I) can be determined from the phase difference between the current amplitude and the input signal. Cut.

[0095] The frequency of the applied voltage signal is used as a parameter, and the resulting impedance is displayed on the complex plane. This is called a Nyquist plot. By determining the impedance (Z), the basic The fundamental transfer function, including admittance (Y), modulus (M), and permittivity (ε), is determined. This is possible. The relationships between each transfer function are shown below.

[0096] [Table 1]

[0097] In this embodiment, an impedance (Z) plot is shown from the real axis, and the resistance component is shown. We analyzed the light-emitting device using a modulus (M) plot, which shows the reciprocal of the quantitative component. Table 2 shows the element configuration of the light-emitting device that was measured.

[0098] [Table 2]

[0099] Figure 16 shows an example of a Z-plot of a light-emitting device according to one embodiment of the present invention. Since it represents the resistance component, it indicates that the resistance after driving is significantly lower than the resistance before driving. This can be seen. Thus, the light-emitting device according to one aspect of the present invention has a large resistance before and after operation. The resistance changed, and it was found that the resistance of the light-emitting device decreased after driving compared to before driving.

[0100] Next, Figure 17 shows the M-plot of the same light-emitting device. Equivalent circuit analysis was performed on this graph. Software ZView (Scribner Associates (Scribner Associates) The fitting was performed by Societies / USA, and the equivalent circuit of this light-emitting device is as follows: This could be represented by four RC parallel circuits and one series resistor as shown in Figure 18. The values ​​within the lot represent the resistance components of the corresponding equivalent circuit obtained through fitting. It indicates the location.

[0101] Furthermore, Figure 19 shows the resistance before and after driving for each resistance component shown in the equivalent circuit in Figure 18. The values ​​were shown. From this, it was found that the resistance of resistor R2 was more than an order of magnitude smaller.

[0102] Therefore, we measured which layer each resistance component corresponds to by changing the film thickness, and increased the film thickness. From the change in the M plot and the increase in resistance, it can be concluded that the resistance component of R2 originates from the electron transport layer. I confirmed that this was the case.

[0103] These results suggest that by passing current through the light-emitting device and driving it, the electron transport layer 114 We were able to confirm that the resistance decreased and the electron transportability of the electron transport layer 114 increased. As the electron transportability of the electron transport layer 114 increases, the carrier balance changes as described above. When recombination occurs, the ends of the recombination region that had extended to the electron transport layer move towards the light-emitting layer, resulting in non-luminescence. The recombination region 120 decreases. As a result, recombination within the light-emitting layer increases, and the energy of recombination This makes it possible to effectively contribute energy to light emission. The device is a light-emitting device that exhibits characteristic behavior in which brightness increases compared to the initial stage of operation. Yes.

[0104] Thus, the light-emitting device according to one aspect of the present invention has a resistance after driving that is lower than the resistance before driving. It was found that, when driven, the resistance of the electron transport layer decreases, making it a light-emitting device. It was found that the electron transport layer drives the light-emitting device, that is, it conducts electric current. This means that the material is composed of materials whose resistivity decreases as a result.

[0105] A light-emitting device according to one aspect of the present invention having the above configuration is a light-emitting device with a very good lifespan. It can be used as a vice, especially in the region where degradation is extremely small, up to around LT95. It is possible to significantly extend lifespan.

[0106] Furthermore, the ability to suppress initial degradation is one of the major weaknesses of OLED devices. The issue of seizing, which is still a subject of discussion, and the pre-shipment aging process taken to reduce it. This makes it possible to significantly reduce the time between steps.

[0107] (Embodiment 2) Next, we will describe the detailed structure and materials of the light-emitting device mentioned above. One aspect of the present invention As described above, the light-emitting device consists of multiple layers between a pair of electrodes, an anode 101 and a cathode 102. It has an EL layer 103, and the EL layer 103 is at least from the anode 101 side, a hole injection layer 111, first hole transport layer 112-1, second hole transport layer 112-2, light-emitting layer 113 It includes an electron transport layer 114.

[0108] Other layers included in the EL layer 103 are not particularly limited, and include hole injection layers and hole transport layers. Layers such as electron transport layers, electron injection layers, carrier blocking layers, exciton blocking layers, and charge generation layers. Various layered structures can be applied.

[0109] Anode 101 is a metal, alloy, or conductive compound with a large work function (specifically, 4.0 eV or more). It is preferable to form them using materials and mixtures thereof. Specifically, for example, Indium tin oxide (ITO), silicon, etc. Or silicon dioxide-containing indium oxide-tin oxide, indium oxide-zinc oxide, oxide Examples include indium oxide (IWZO) containing tungsten and zinc oxide. These conductive metal oxide films are usually deposited by sputtering, but the sol-gel method is also used. Any method can be used to manufacture it. An example of a manufacturing method is indium oxide-zinc oxide. Sputtering is performed using a target to which 1-20 wt% zinc oxide has been added to indium oxide. There are methods such as the ring method for formation. Also, it contains tungsten oxide and zinc oxide. Indium oxide (IWZO) is found to be 0.5 to 5 times more tungsten oxide than indium oxide. Using a target containing wt% and 0.1-1 wt% zinc oxide, the sputtering method is used. It can also be formed from gold (Au), platinum (Pt), nickel (Ni), and tungsten. Gusten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co) copper (Cu), palladium (Pd), or nitrides of metallic materials (e.g., titanium nitride), etc. These include graphene, which can also be used. Note that here the work function is large and explicit While representative materials for forming the electrode have been listed, in one aspect of the present invention, the hole injection layer 1 11. An organic compound having hole transport properties and a substance exhibiting electron-accepting properties for said organic compound. Because a composite material containing these elements is used, the electrode material can be selected regardless of the work function.

[0110] The laminated structure of the EL layer 103 is as shown in Figure 1(A1)(A2) in this embodiment. Sea urchin, hole injection layer 111, first hole transport layer 112-1, second hole transport layer 112-2, Light-emitting layer 113, electron transport layer 114 (first electron transport layer 114-1, second electron transport layer 11 In addition to 4-2), a configuration having an electron injection layer 115, and as shown in Figure 1(B), Two types of configurations will be described, in which the inlet layer 115 is replaced with a charge generation layer 116. The materials that make up the layers are described below in detail.

[0111] Hole injection layer 111, hole transport layer 112 (first hole transport layer 112-1, second hole transport layer 112-2), light-emitting layer 113 and electron transport layer 114 (first electron transport layer 114-1, the Regarding electron transport layer 2 (114-2), it was described in detail in Embodiment 1, so this is a repetition. The details are omitted. Please refer to the description of Embodiment 1.

[0112] Between the electron transport layer 114 and the cathode 102, an electron injection layer 115 is provided, which is lithium fluoride. Alkaline compounds such as LiF, cesium fluoride (CsF), and calcium fluoride (CaF2) A layer containing an alkaline metal, an alkaline earth metal, or a compound thereof may be provided. Electron injection layer 1 15 is a layer made of an electron-transporting material containing alkali metals or alkaline earth metals or Products containing those compounds or electrides may also be used. Electrides and For example, a substance obtained by adding a high concentration of electrons to a mixed oxide of calcium and aluminum. These are some examples.

[0113] In addition, instead of the electron injection layer 115, a charge generation layer 1 is placed between the electron transport layer 114 and the cathode 102. 16 may be provided (Figure 1(B)). The charge generation layer 116 is generated by applying a potential. A layer in which holes can be injected into the layer in contact with the cathode side and electrons into the layer in contact with the anode side. The charge generation layer 116 includes at least a P-type layer 117. This uses the composite material listed above as a material that can constitute the hole injection layer 111. It is preferable to form it. Furthermore, the P-type layer 117 is made of the materials described above as constituting the composite material. The structure may be constructed by laminating a film containing an acceptor material and a film containing a hole transport material. P-type layer 1 By applying an electric potential to 17, electrons are directed to the electron transport layer 114 and to the cathode 102. Holes are injected, and the light-emitting device starts working.

[0114] In addition to the P-type layer 117, the charge generation layer 116 also includes an electron relay layer 118 and an electron injection buffer. It is preferable that one or both of the layers 119 are provided.

[0115] The electron relay layer 118 contains at least an electron-transporting material, and the electron injection buffer layer 1 It has the function of preventing interaction between 19 and the P-type layer 117, thereby enabling smooth electron transfer. The LUMO level of the electron-transporting material contained in the relay layer 118 is in the P-type layer 117. The LUMO level of the electron-accepting material and the charge generation layer 116 in the electron transport layer 114 are in contact. It is preferable that the LUMO level is between the LUMO level of the material contained in the layer. Electron relay layer 118 The specific energy levels of the LUMO level in electron-transporting materials used are It is preferable to have a voltage of -5.0 eV or higher, preferably between -5.0 eV and -3.0 eV. As for the electron-transporting material used in the electron relay layer 118, phthalocyanine-based materials are used. It is preferable to use a metal complex having a metal-oxygen bond and an aromatic ligand.

[0116] The electron injection buffer layer 119 contains alkali metals, alkaline earth metals, rare earth metals, and These compounds (alkali metal compounds (oxides such as lithium oxide, halides, and carbonates) (including carbonates such as thium and cesium carbonate), alkaline earth metal compounds (oxides, halogens) Compounds of rare earth metals (including oxides, halides, and carbonates), or compounds of rare earth metals (including oxides, halides, and carbonates) It is possible to use materials with high electron injection capabilities, such as (m)).

[0117] Furthermore, the electron injection buffer layer 119 contains an electron transporting material and an electron donating material. If formed, the electron-donating substances are alkali metals, alkaline earth metals, and rare earth elements. Metals, and their compounds (alkali metal compounds (oxides such as lithium oxide, halogens) (including carbonates such as lithium carbonate and cesium carbonate), alkaline earth metal compounds (oxidation) (including substances, halides, and carbonates), or compounds of rare earth metals (oxides, halides) In addition to carbonates, tetrathianaphthalene (abbreviation: TTN), nickelosene, and decane are also included. Organic compounds such as methyl nickerosene can also be used. Furthermore, substances with electron transport properties... In terms of quality, it is formed using the same material as the material that constitutes the electron transport layer 114 described earlier. It is possible.

[0118] As the material that forms cathode 102, gold with a small work function (specifically, 3.8 eV or less) is used. Compounds, alloys, electrically conductive compounds, and mixtures thereof can be used. Specific examples of cathode materials include alkali metals such as lithium (Li) and cesium (Cs). , and elements such as magnesium (Mg), calcium (Ca), and strontium (Sr). Elements belonging to Group 1 or Group 2 of the periodic table, and alloys containing them (MgAg, AlL i) Rare earth metals such as europium (Eu) and ytterbium (Yb), and those containing these Examples include alloys, etc. However, between the cathode 102 and the electron transport layer, an electron injection layer is provided. By providing this, regardless of the magnitude of the work function, Al, Ag, ITO, silicon, or acid Various conductive materials such as indium oxide-tin oxide containing silicon dioxide are used as cathode 102. It is possible to be there. These conductive materials are produced using dry methods such as vacuum deposition and sputtering, as well as inkjet methods. It is possible to deposit films using methods such as spin coating. Furthermore, wet deposition can be performed using the sol-gel method. It may be formed by a mold, or by a wet process using a paste of a metallic material.

[0119] Furthermore, various methods can be used to form the EL layer 103, regardless of whether they are dry or wet methods. This can be done using methods such as vacuum deposition, gravure printing, offset printing, and screen printing. You may use methods such as printing, inkjet printing, or spin coating.

[0120] Furthermore, each electrode or layer described above may be formed using different film deposition methods.

[0121] The configuration of the layer provided between the anode 101 and the cathode 102 is not limited to the above. No. However, the proximity of the light-emitting region to the metal used in the electrodes and carrier injection layer can lead to... To suppress the resulting quenching, holes are placed in a location away from the anode 101 and cathode 102. A configuration in which a light-emitting region is provided where electrons and other elements recombine is preferable.

[0122] Furthermore, the hole transport layer and electron transport layer in contact with the light-emitting layer 113, and especially the recombination in the light-emitting layer 113, The carrier transport layer near the region suppresses energy transfer from excitons generated in the light-emitting layer. Therefore, the band gap is the luminescent material that makes up the luminescent layer or the luminescence contained in the luminescent layer. It is preferable to use materials with a band gap larger than the band gap of the material itself. It seems so.

[0123] Next, we have a light-emitting device (multilayer element, tandem element) with a configuration in which multiple light-emitting units are stacked. The form of the (also called the child) will be explained with reference to Figure 1(C). This light-emitting device is positive This is a light-emitting device having multiple light-emitting units between the electrode and the cathode. The structure is substantially the same as the EL layer 103 shown in Figure 1(A1) or (A2). In other words, the light-emitting device shown in Figure 1(C) is a light-emitting device having multiple light-emitting units. The light-emitting devices shown in Figures 1(A1)(A2) and 1(B) have one light-emitting unit. It can be said to be a light-emitting device.

[0124] In Figure 1(C), a first light-emitting unit 511 and a cathode 502 are located between the anode 501 and the cathode 502. A second light-emitting unit 512 is stacked with the first light-emitting unit 511 and the second light-emitting unit A charge generation layer 513 is provided between the knit 512 and the cathode 502. These correspond to the anode 101 and cathode 102 in Figure 1(A1), respectively, and in the explanation of Figure 1(A1) The same thing described can be applied. Also, the first light-emitting unit 511 and the second The light-emitting unit 512 may have the same configuration or a different configuration.

[0125] When a voltage is applied to the anode 501 and cathode 502, the charge generation layer 513 generates a light from one of the light-emitting units. It has the function of injecting electrons into one unit and holes into the other light-emitting unit. That is, Figure In 1(C), when a voltage is applied such that the potential of the anode is higher than the potential of the cathode... In addition, the charge generation layer 513 injects electrons into the first light-emitting unit 511 and the second light-emitting unit Any method that injects a hole into T512 will suffice.

[0126] The charge generation layer 513 is formed with the same configuration as the charge generation layer 116 described in Figure 1(B). Preferably, composite materials of organic compounds and metal oxides have good carrier implantation and carrier transport properties. Due to its superior performance, it can achieve low-voltage and low-current operation. If the anode side of the net is in contact with the charge generation layer 513, the charge generation layer 513 will light up the unit. Since it can also serve as the hole injection layer of the net, the light-emitting unit does not require a hole injection layer. That's fine.

[0127] Furthermore, if an electron injection buffer layer 119 is provided in the charge generation layer 513, the electron injection buffer Since layer 119 plays the role of an electron injection layer in the anode-side light-emitting unit, the anode-side light emission The unit does not necessarily need to have an electron injection layer.

[0128] Figure 1(C) illustrates a light-emitting device having two light-emitting units, but there are also devices with three or more units. The same method can be applied to light-emitting devices that stack the above light-emitting units. As in the light-emitting device according to this embodiment, multiple light-emitting units are charged between a pair of electrodes. By separating and arranging the elements with the generation layer 513, high-brightness light emission is possible while maintaining a low current density. This enables the realization of even longer-lasting elements. Furthermore, it allows for low-voltage operation and low power consumption of light-emitting elements. The device can be realized.

[0129] Furthermore, by making the light-emitting color of each light-emitting unit different, the entire light-emitting device... This allows you to obtain light emission of the desired color. For example, a light emission device having two light emission units In the vise, the first light-emitting unit emits red and green light, and the second light-emitting unit emits blue light. By obtaining color, it is also possible to obtain a light-emitting device that emits white light as a whole. Yes, there is. Furthermore, an example of a light-emitting device configuration in which three or more light-emitting units are stacked is: The first light-emitting unit has a first blue light-emitting layer, and the second light-emitting unit has a yellow or yellowish-green light-emitting layer. The third light-emitting unit has a colored light-emitting layer and a red light-emitting layer, and the third light-emitting unit has a second blue light-emitting layer. This can be a tandem type device. This tandem type device is the above-mentioned light-emitting device Similar to the chair, it can emit white light.

[0130] Furthermore, the EL layer 103, the first light-emitting unit 511, the second light-emitting unit 512 and Each layer, such as the charge generation layer, and the electrodes are, for example, deposited by methods such as vapor deposition (including vacuum deposition) and droplet ejection ( It can be formed using methods such as inkjet printing, coating, and gravure printing. They can be used. Also, they include low molecular weight materials, medium molecular weight materials (including oligomers and dendrimers), and Alternatively, it may contain polymer materials.

[0131] (Embodiment 3) In this embodiment, light emission using the light-emitting device described in Embodiment 1 and Embodiment 2 is demonstrated. Let me explain the device.

[0132] In this embodiment, the light-emitting device described in Embodiment 1 and Embodiment 2 is used for fabrication. The light-emitting device described will be explained using Figure 4. Figure 4(A) shows the light-emitting device. The top view, Figure 4(B), is a cross-sectional view of Figure 4(A) cut along lines AB and CD. This light emission The device controls the light emission of the light-emitting device, and the drive circuit section (source) is shown by the dotted line. It includes a line drive circuit (601), a pixel section (602), and a drive circuit section (gate line drive circuit) (603). Furthermore, 604 is the sealing substrate, and 605 is the sealing material, and the inside surrounded by the sealing material 605 This is space 607.

[0133] The routing wire 608 is input to the source line drive circuit 601 and the gate line drive circuit 603. FPC (Flexible Printed Circuit) is a wiring system for transmitting signals and serves as an external input terminal. (Input circuit) 609 receives video signals, clock signals, start signals, reset signals, etc. Receive. Note that only the FPC is shown in the diagram here, but this FPC has a print distribution A wire substrate (PWB) may be attached. The light-emitting device in this specification is a light-emitting device This includes not only the main unit but also the state in which the FPC or PWB is attached to it. ru.

[0134] Next, the cross-sectional structure will be explained using Figure 4(B). The drive circuit section is located on the element substrate 610. And a pixel section is formed, but here, the source line drive circuit 601 which is the drive circuit section and One pixel in the pixel section 602 is shown.

[0135] The element substrate 610 is a substrate made of glass, quartz, organic resin, metal, alloy, semiconductor, etc. FRP (Fiber Reinforced Plastics), PVF (Polyvinyl Fiber) It is made using a plastic substrate made of fluoride, polyester, or acrylic. That's all you need to do.

[0136] The structure of transistors used in pixels and driving circuits is not particularly limited. For example, inverse staggered It can be a type of transistor or a staggered transistor. Also, top Either a gate-type transistor or a bottom-gate transistor is acceptable. The semiconductor material is not particularly limited, and examples include silicon, germanium, silicon carbide, nitride Gallium can be used, or an In-Ga-Zn metal oxide can be used. An oxide semiconductor containing at least one of the elements, such as zinc, gallium, and zinc, may also be used.

[0137] The crystallinity of semiconductor materials used in transistors is not particularly limited; amorphous semiconductors, Crystalline semiconductors (microcrystalline semiconductors, polycrystalline semiconductors, single-crystal semiconductors, or semiconductors with a crystalline region in part) Any semiconductor having the properties of [the semiconductor material] may be used. If a semiconductor having crystalline properties is used, transients may occur. This is preferable because it suppresses the deterioration of the stanic characteristics.

[0138] Here, in addition to the transistors provided in the pixels and driving circuits mentioned above, the touch sensors and the like described later are also included. It is preferable to use oxide semiconductors for semiconductor devices such as transistors. It is particularly preferable to use oxide semiconductors with a wider band gap than silicon. By using an oxide semiconductor with a wider band gap than Ricon, the off state of the transistor can be controlled. The current in this state can be reduced.

[0139] The above oxide semiconductor preferably contains at least indium (In) or zinc (Zn). It is also In-M-Zn oxides (where M is Al, Ti, Ga, Ge, Y, Zr, Sn, It is an oxide semiconductor containing an oxide (such as a metal like La, Ce, or Hf). It is preferable.

[0140] Herein, an oxide semiconductor that can be used in one aspect of the present invention will be described below. .

[0141] Oxide semiconductors are divided into single-crystal oxide semiconductors and other non-single-crystal oxide semiconductors. As a non-single-crystal oxide semiconductor, for example, CAAC-OS (c-axis ali gned crystalline oxide semiconductor), polycrystalline crystalline oxide semiconductor, nc-OS (nano crystalline oxide sem iconductor), pseudo-amorphous oxide semiconductor (a-like OS: amorph (Amorphous-like oxide semiconductor), and amorphous oxide semiconductor It contains conductors, etc.

[0142] CAAC-OS has c-axis orientation and multiple nanocrystals are linked in the ab-plane direction. Furthermore, it has a distorted crystal structure. Note that distortion refers to the region where multiple nanocrystals are connected. Within the region, between a region with aligned lattice arrangements and another region with aligned lattice arrangements, This refers to the part where the direction has changed.

[0143] Nanocrystals are based on a hexagonal structure, but they are not necessarily regular hexagons; they can also be non-regular hexagonal. Yes, it exists. Furthermore, the distortion may have lattice arrangements such as pentagons and heptagons. Furthermore, in CAAC-OS, even near strain, clear grain boundaries (grain bounds) are present. It is difficult to confirm (also called Dally) the crystal grains. In other words, due to the distortion of the lattice arrangement, It can be seen that the formation of the boundary is suppressed. This is because CAAC-OS is in the ab-plane direction. The oxygen atoms are not densely arranged, and the substitution of metal elements reduces the bond distance between atoms. This is because distortion can be tolerated through changes and other processes.

[0144] Furthermore, CAAC-OS consists of a layer containing indium and oxygen (hereinafter referred to as the In layer), and elements A layered crystalline structure in which layers containing M, zinc, and oxygen (hereinafter referred to as (M,Zn) layers) are stacked. It tends to have a layered structure (also called a structure). Furthermore, indium and element M are substituted for each other. It is possible, and if element M in the (M,Zn) layer is replaced with indium, then (In,M,Zn) It can also be represented as a layer. Furthermore, if the indium in the In layer is substituted with element M, then (In,M It can also be represented as a layer.

[0145] CAAC-OS is a highly crystalline oxide semiconductor. On the other hand, CAAC-OS has a clear bond. Because it is difficult to confirm grain boundaries, a decrease in electron mobility caused by grain boundaries is less likely to occur. It can be said that... Furthermore, the crystallinity of oxide semiconductors decreases due to the inclusion of impurities and the generation of defects. Because this can occur, CAAC-OS may contain impurities or defects (oxygen deficiencies (V O :oxygen It can also be described as an oxide semiconductor with low vacancy (also called CAA). Therefore, CAA Oxide semiconductors containing C-OS exhibit stable physical properties. Therefore, CAAC-OS The oxide semiconductors it possesses are highly heat-resistant and reliable.

[0146] nc-OS is used in minute regions (for example, regions between 1 nm and 10 nm, especially between 1 nm and 3 nm). It has periodicity in the atomic arrangement in the region of less than nm. Furthermore, nc-OS has different nanometers. No regularity in crystal orientation is observed between crystals. Therefore, no orientation is observed throughout the entire film. Therefore, depending on the analysis method, nc-OS can be classified as a-like OS or amorphous oxide semiconductor. It can sometimes be difficult to distinguish between them.

[0147] Furthermore, indium is a type of oxide semiconductor containing indium, gallium, and zinc. Um-gallium-zinc oxide (hereinafter referred to as IGZO) is stable when formed into the nanocrystals described above. It may take on a structure. In particular, IGZO tends to have difficulty growing crystals in the atmosphere. Smaller crystals (for example) are preferable to larger crystals (here, crystals of a few millimeters or a few centimeters). In some cases, using the aforementioned nanocrystal structure may result in greater structural stability.

[0148] a-like OS is an oxide semiconductor having a structure between nc-OS and amorphous oxide semiconductors. It is a conductor. a-like OS has porous or low-density regions. That is, a-li ke OS has lower crystallinity compared to nc-OS and CAAC-OS.

[0149] Oxide semiconductors can take on diverse structures, each possessing different properties. One embodiment of the present invention Oxide semiconductors include amorphous oxide semiconductors, polycrystalline oxide semiconductors, a-like OS, and nc -OS and CAAC-OS may have two or more types.

[0150] In addition to the oxide semiconductors mentioned above, CAC (Cloud-Aligned Comp You may also use osite)-OS.

[0151] CAC-OS refers to a material that possesses both conductive and insulating properties in some parts. Furthermore, the material as a whole possesses semiconductor functionality. Note that CAC-OS is used in transistors. When used in semiconductor layers, the conductive function is to allow electrons (or holes) that act as carriers to flow. The function of insulation is the function of preventing the flow of electrons, which act as carriers. The function of conductivity is... By having the insulating function and the other function work complementaryly, a switching function is achieved. The function to turn CAC-OS on / off can be added to CAC-OS. By separating each function, it is possible to maximize the performance of both.

[0152] Furthermore, CAC-OS has conductive regions and insulating regions. The conductive region is the conductive region described above. It has electrical properties, and the insulating region has the aforementioned insulating properties. Furthermore, in the material In some cases, the conductive region and the insulating region are separated at the nanoparticle level. The electrically conductive region and the insulating region may be unevenly distributed within the material. In some cases, the surrounding area may appear blurred and connected in a cloud-like manner.

[0153] Furthermore, in CAC-OS, the conductive region and the insulating region are each 0.5 nm or greater. In the case where particles are dispersed in the material with a size of 10 nm or less, preferably 0.5 nm to 3 nm. There is a match.

[0154] Furthermore, CAC-OS is composed of components with different band gaps. For example, CAC-OS consists of a component with a wide gap due to the insulating region and a component that occurs in the conductive region. It is composed of a component having a narrow gap due to and . In this configuration, the carrier When flowing, the carrier mainly flows in the component with a narrow gap. Components with gaps act complementaryly with components with wide gaps, and narrow gaps In conjunction with the component having a gap, the carrier also flows to the component having a wide gap. When the above CAC-OS is used in the channel formation region of a transistor, the transistor In the ON state, a high current driving force, i.e., a large ON current and high field effect mobility are obtained. It is possible.

[0155] In other words, CAC-OS is a matrix composite. , or metal matrix composite and It can also be referred to as such.

[0156] By using the aforementioned oxide semiconductor material as the semiconductor layer, fluctuations in electrical properties are suppressed, and reliability This enables the creation of highly reliable transistors.

[0157] Furthermore, due to its low off-current, the transistor having the aforementioned semiconductor layer can be used to... This makes it possible to retain the charge stored in the capacity over a long period of time. By applying a generator to each pixel, the gradation of the image displayed in each display area is maintained while driving It also becomes possible to shut down the circuit. As a result, it is possible to realize electronic devices with extremely reduced power consumption. It can be expressed.

[0158] It is preferable to provide an undercoat to stabilize the characteristics of the transistor. The undercoat may be: Inorganic silicon oxide films, silicon nitride films, silicon oxide-nitride films, silicon nitride-oxide films, etc. It can be fabricated using an insulating film, either as a single layer or in a multilayer configuration. The underlayer is fabricated by sputtering. CVD (Chemical Vapor Deposition) method (Plasma CVD method) , thermal CVD method, MOCVD (Metal Organic CVD) method, ALD ( Formed using methods such as Atomic Layer Deposition, coating, and printing. Yes, it is possible. However, a base coat does not need to be applied unless necessary.

[0159] Note that FET623 is one of the transistors formed in the drive circuit section 601. Furthermore, the drive circuit is formed using various CMOS, PMOS, or NMOS circuits. This is sufficient. Furthermore, this embodiment shows a driver-integrated type in which the drive circuit is formed on the substrate. However, this is not always necessary, and the drive circuit can be formed externally rather than on the circuit board. .

[0160] Furthermore, the pixel section 602 includes a switching FET 611 and a current control FET 612 and its drive It is formed by multiple pixels, including an anode 613 electrically connected to the rain, The pixel section may also be a combination of three or more FETs and a capacitive element.

[0161] Furthermore, an insulator 614 is formed covering the end of the anode 613. Here, a positive type sensor It can be formed by using light-sensitive acrylic.

[0162] Furthermore, in order to ensure good coverage of the EL layer and other layers formed later, the upper end of the insulator 614 is Alternatively, a curved surface with curvature is formed at the lower end. For example, the material of the insulator 614 and When a positive-type photosensitive acrylic is used, the radius of curvature (0.) is only at the upper end of the insulator 614. It is preferable to have a curved surface having a thickness of 2 μm to 3 μm. Also, as the insulator 614, Either a negative-type or positive-type photosensitive resin can be used.

[0163] An EL layer 616 and a cathode 617 are formed on the anode 613, respectively. Therefore, it is desirable to use a material with a large work function for the anode 613. For example, an ITO film, or an indium tin oxide film containing silicon, 2-20 wt% oxidation Indium oxide film containing zinc, titanium nitride film, chromium film, tungsten film, Zn film, Pt In addition to single-layer films such as membranes, lamination of titanium nitride films and films mainly composed of aluminum, titanium nitride A three-layer structure consisting of a film, a film mainly composed of aluminum, and a titanium nitride film can be used. Furthermore, a laminated structure results in low resistance as wiring and good ohmic contact. Furthermore, it can be used as an anode.

[0164] Furthermore, the EL layer 616 was coated using a vapor deposition method with a vapor deposition mask, an inkjet method, and a spin coating method. It is formed by various methods such as the above. The EL layer 616 is formed by Embodiment 1 and Embodiment 2 It includes the configuration described above. Furthermore, other materials constituting the EL layer 616 include: It may be a low-molecular-weight compound or a high-molecular-weight compound (including oligomers and dendrimers). .

[0165] Furthermore, the material used for the cathode 617 formed on the EL layer 616 has a small work function. Materials (Al, Mg, Li, Ca, or alloys and compounds thereof (MgAg, MgIn, It is preferable to use AlLi, etc. Furthermore, the light generated in the EL layer 616 is directed to the cathode 617 When allowing light to pass through, the cathode 617 consists of a thin metal film and a transparent conductive film (I TO, indium oxide containing 2-20 wt% zinc oxide, and indium tin containing silicon. It is preferable to use lamination with oxides (such as zinc oxide (ZnO)).

[0166] The anode 613, EL layer 616, and cathode 617 form the light-emitting device. The light-emitting device is the light-emitting device described in Embodiment 1 and Embodiment 2. Oh, the pixel section is made up of multiple light-emitting devices, but the light emission in this embodiment The apparatus includes the light-emitting device described in Embodiment 1 and Embodiment 2, and other components. It may include both of the light-emitting devices.

[0167] Furthermore, by bonding the sealing substrate 604 to the element substrate 610 with the sealing material 605, A light-emitting device is placed in the space 607 surrounded by the sub-substrate 610, the sealing substrate 604, and the sealing material 605. The structure is equipped with chair 618. Furthermore, the space 607 is filled with filler material. In addition to cases where inert gases (such as nitrogen or argon) are used for filling, there are also cases where sealing materials are used for filling. There are also cases where a recess is formed in the sealing substrate and a desiccant is placed there to prevent deterioration due to moisture. This configuration is preferable because it can suppress oxidation.

[0168] Furthermore, it is preferable to use epoxy resin or glass frit for the sealing material 605. These materials should ideally be as impermeable to moisture and oxygen as possible. In addition to glass substrates and quartz substrates, other materials can be used for the encapsulating substrate 604, such as FRP (Fiber Reinforced Plastic). reinforced plastics, PVF (polyvinyl fluoride), polyester A plastic substrate made of tel or acrylic can be used.

[0169] Although not shown in Figure 4, a protective film may be provided on the cathode. The protective film may be an organic resin film or an inorganic film. It can be formed with an insulating film. Also, a protective film can be made to cover the exposed portion of the sealing material 605. It may be formed. Also, the protective film may be on the surface and sides of the pair of substrates, a sealing layer, an insulating layer, It can be installed to cover exposed sides such as those shown.

[0170] The protective film can be made of a material that is impermeable to impurities such as water. This effectively suppresses the diffusion of impurities such as these from the outside to the inside.

[0171] Materials that make up the protective film include oxides, nitrides, fluorides, sulfides, ternary compounds, and metals. Alternatively, polymers can be used, for example, aluminum oxide, hafnium oxide, etc. Phenium silicate, lanthanum oxide, silicon oxide, strontium titanate, tantalum oxide Titanium dioxide, zinc oxide, niobium oxide, zirconium oxide, tin oxide, yttrium oxide cerium oxide, scandium oxide, erbium oxide, vanadium oxide, or indi oxide Materials containing um, etc., as well as aluminum nitride, hafnium nitride, silicon nitride, tantalum nitride, nitrogen Includes titanium dioxide, niobium nitride, molybdenum nitride, zirconium nitride, or gallium nitride, etc. Materials, nitrides containing titanium and aluminum, oxides containing titanium and aluminum oxides containing aluminum and zinc, sulfides containing manganese and zinc, cerium oxides Strontium-containing sulfides, erbium and aluminum-containing oxides, and Materials containing oxides, etc., including lium and zirconium can be used.

[0172] The protective film can be formed using a film deposition method that provides good step coverage. This is preferable. One such method is atomic layer deposition (ALD). There is a deposition method. Protecting materials that can be formed using the ALD method. It is preferable to use it for membranes. By using the ALD method, a dense membrane can be created with cracks and pinholes. A protective film can be formed with reduced defects or with a uniform thickness. Also, This reduces the damage inflicted on the processed material when forming a protective film.

[0173] For example, by forming a protective film using the ALD method, surfaces with complex uneven shapes, or taps can be formed. A uniform and low-defect protective film can be formed on the top, sides, and back surfaces of the panel. .

[0174] As described above, the light-emitting devices described in Embodiments 1 and 2 are used to manufacture the light-emitting devices. A light-emitting device can be obtained.

[0175] The light-emitting device in this embodiment is the same as the light-emitting device described in Embodiment 1 and Embodiment 2. Because it uses a specific material, a light-emitting device with good characteristics can be obtained. Specifically, The light-emitting devices described in Embodiment 1 and Embodiment 2 are long-life light-emitting devices. Therefore, a highly reliable light-emitting device can be made. Also, Embodiment 1 and Embodiment Because the light-emitting device using the light-emitting device described in 2 has good luminous efficiency, it consumes little power. It can be used as an optical device.

[0176] Figure 5 shows a light-emitting device that emits white light, with a colored layer (color filter) provided. This shows an example of a light-emitting device that has been made full-color. Figure 5(A) shows substrate 1001, base Insulating film 1002, gate insulating film 1003, gate electrodes 1006, 1007, 1008, Interlayer insulating film 1020, second interlayer insulating film 1021, peripheral portion 1042, pixel portion 1040 , drive circuit section 1041, anodes 1024W, 1024R, 1024G, 10 24B, partition wall 1025, EL layer 1028, cathode of light-emitting device 1029, sealing substrate 103 1. The sealing material 1032 and other components are shown in the diagram.

[0177] Furthermore, Figure 5(A) shows the colored layers (red colored layer 1034R, green colored layer 1034G, blue The colored layer 1034B is provided on a transparent substrate 1033. Also, the black matrix 1 A 035 layer may be further provided. Transparent substrate 1 provided with a colored layer and a black matrix. 033 is aligned and fixed to substrate 1001. Note that the colored layer and black matrix Kus 1035 is covered with an overcoat layer 1036. Also, in Figure 5(A) This consists of a light-emitting layer that allows light to escape to the outside without passing through the colored layers, and a layer that allows light to escape to the outside by passing through the colored layers of each color. There is a light-emitting layer, and light that does not pass through the colored layer is white, while light that passes through the colored layer is red, green, and blue. Therefore, images can be represented using four colored pixels.

[0178] Figure 5(B) shows the colored layers (red colored layer 1034R, green colored layer 1034G, blue colored layer Example of forming layer 1034B) between the gate insulating film 1003 and the first interlayer insulating film 1020. This was shown. Thus, the colored layer is provided between the substrate 1001 and the sealing substrate 1031. That's good too.

[0179] Furthermore, in the light-emitting device described above, light is taken to the substrate 1001 side on which the FET is formed. Although a light-emitting device with a bottom-emission structure was used, the light emission was taken from the sealing substrate 1031 side. It can also be used as a light-emitting device with a projection structure (top emission type). A cross-sectional view of the light-emitting device is shown in Figure 6. In this case, the substrate 1001 is a substrate that does not transmit light. This can be done. Until the connecting electrode that connects the FET and the anode of the light-emitting device is fabricated, the bottle It is formed in the same way as a muemission-type light-emitting device. Then, the third interlayer insulating film 1037 is electrically... It is formed covering pole 1022. This insulating film may also play a planarization role. Third layer The interlayer insulating film 1037 is formed using the same material as the second interlayer insulating film, as well as other known materials. It is possible.

[0180] The anodes 1024W, 1024R, 1024G, and 1024B of the light-emitting devices are referred to here as anodes. However, it is also acceptable to form it as a cathode. Furthermore, a top-emission type reactor as shown in Figure 6... In the case of an optical device, it is preferable to use the anode as a reflective electrode. The configuration of the EL layer 1028 is as follows: The configuration is as described in Embodiment 1 and Embodiment 2 as the EL layer 103, and The element structure is designed to produce white light emission.

[0181] In the top emission structure shown in Figure 6, the colored layer (red colored layer 1034R, green colored layer) The sealing is performed using a sealing substrate 1031 having a color layer 1034G and a blue colored layer 1034B. This can be done. The encapsulation substrate 1031 has a black matrix positioned between the pixels. 1035 may be provided. Colored layer (red colored layer 1034R, green colored layer 1034G, The blue colored layer (1034B) and the black matrix are covered by an overcoat layer. It is acceptable to leave it there. Furthermore, the sealing substrate 1031 shall be a light-transmitting substrate. Here, we have shown an example of full-color display using four colors: red, green, blue, and white, but it is not particularly limited to red, Full-color display may be performed using four colors: yellow, green, and blue, or three colors: red, green, and blue.

[0182] In top-emission type light-emitting devices, a microcavity structure can be suitably applied. A light-emitting device having a microcavity structure has a reflective electrode as the anode and a semi-transparent / semi-reflective cathode. This is obtained by using a ray electrode. Between the reflective electrode and the semitransmissive / semi-reflective electrode, there is at least It has an EL layer and at least an emissive layer that forms an emissive region.

[0183] The reflective electrode has a visible light reflectance of 40% to 100%, preferably 70% to 100%. It is %, and its resistivity is 1 × 10⁻⁶. -2 Assume the membrane is less than Ωcm in diameter. Also, semipermeable... The semi-reflective electrode has a visible light reflectance of 20% to 80%, preferably 40% to 70%. , and its resistivity is 1 × 10 -2 Assume the membrane is less than Ωcm in diameter.

[0184] The light emitted from the light-emitting layer contained in the EL layer is reflected by the reflective electrode and the semi-transmitting / semi-reflective electrode. It is reflected and resonates.

[0185] The light-emitting device changes the thickness of the transparent conductive film, the aforementioned composite material, the carrier transport material, etc. This allows us to change the optical distance between the reflective electrode and the semitransmissive / semi-reflective electrode. Furthermore, the light of the resonant wavelength is amplified between the reflective electrode and the semitransmissive / semi-reflective electrode, causing resonance. It can attenuate light of wavelengths that are not present.

[0186] Furthermore, the light reflected back by the reflective electrode (the first reflected light) is semi-transmitted from the light-emitting layer. • Because it causes significant interference with the light (first incident light) that directly enters the semi-reflecting electrode, the reflective electrode and The optical distance of the light-emitting layer is (2n-1)λ / 4 (where n is a natural number greater than or equal to 1, and λ is amplified). It is preferable to adjust the wavelength of the emitted light. By adjusting the optical distance, the first By aligning the phase of the reflected light and the first incident light, the light emitted from the light-emitting layer can be further amplified. ru.

[0187] Furthermore, in the above configuration, even if the EL layer has a structure with multiple light-emitting layers, a single light-emitting layer The structure may have layers, for example, in combination with the configuration of the tandem light-emitting device described above. In addition, multiple EL layers are provided in a single light-emitting device with a charge generation layer in between, and each EL This can also be applied to configurations in which one or more light-emitting layers are formed in a layer.

[0188] Having a microcavity structure enhances the emission intensity in the front direction at specific wavelengths. This makes it possible to reduce power consumption. Furthermore, the four sub-colors red, yellow, green, and blue are used. In the case of a light-emitting device that displays images as is, in addition to the brightness enhancement effect of yellow light emission, all sub-pixels By applying a microcavity structure tailored to the wavelength of each color, a light-emitting device with excellent characteristics can be produced. It can be placed there.

[0189] The light-emitting device in this embodiment is the same as the light-emitting device described in Embodiment 1 and Embodiment 2. Because it uses a specific material, a light-emitting device with good characteristics can be obtained. Specifically, The light-emitting devices described in Embodiment 1 and Embodiment 2 are long-life light-emitting devices. Therefore, a highly reliable light-emitting device can be made. Also, Embodiment 1 and Embodiment Because the light-emitting device using the light-emitting device described in 2 has good luminous efficiency, it consumes little power. It can be used as an optical device.

[0190] Up to this point, we have explained active-matrix light-emitting devices, but from here on we will discuss passive devices. A matrix-type light-emitting device will be described. Figure 7 shows a passive light-emitting device fabricated by applying the present invention. This shows a matrix-type light-emitting device. Figure 7(A) is a perspective view showing the light-emitting device, Figure 7( B) is a cross-sectional view obtained by cutting Figure 7(A) along the XY line. In Figure 7, on the substrate 951, An EL layer 955 is provided between electrode 952 and electrode 956. The end of electrode 952 is It is covered with an insulating layer 953. And a partition layer 954 is provided on top of the insulating layer 953. The side walls of the partition layer 954, as they approach the substrate surface, have a gap between one side wall and the other side wall. It has a slope that narrows as the partition becomes narrower. In other words, the cross-section of the partition wall layer 954 in the short-side direction is It is a shape, and the bottom edge (which faces the same direction as the surface direction of the insulating layer 953 and is in contact with the insulating layer 953) ) is the upper edge (the edge that faces the same direction as the surface direction of the insulating layer 953 and does not come into contact with the insulating layer 953). It is shorter than that. In this way, by providing the partition layer 954, light emission devices caused by static electricity, etc. This can prevent defects in the system. Furthermore, it can also be implemented in passive matrix type light-emitting devices. The light-emitting device described in Embodiment 1 and Embodiment 2 is used, and is a highly reliable light-emitting device It can be used as a light-emitting device with low power consumption.

[0191] The light-emitting device described above consists of numerous tiny light-emitting devices arranged in a matrix. Because these can be controlled, it can be suitably used as a display device for representing images. It is a light-emitting device.

[0192] Furthermore, this embodiment can be freely combined with other embodiments.

[0193] (Embodiment 4) In this embodiment, the light-emitting devices described in Embodiment 1 and Embodiment 2 are used as an illumination device. An example of its use will be explained with reference to Figure 8. Figure 8(B) is a top view of the lighting device, Figure 8( A) is a cross-sectional view of ef in Figure 8(B).

[0194] In this embodiment, the lighting device has an anode 4 on a translucent substrate 400 which is a support. 01 is formed. The anode 401 corresponds to the anode 101 in Embodiment 2. Anode When light is extracted from the 401 side, the anode 401 is formed from a translucent material.

[0195] A pad 412 for supplying voltage to the cathode 404 is formed on the substrate 400.

[0196] An EL layer 403 is formed on the anode 401. The EL layer 403 is the same as in Embodiment 1 and the actual Configuration of the EL layer 103 in the second form of application, or light-emitting units 511, 512 and charge generation This corresponds to a configuration including layer 513, etc. For details on these configurations, please refer to the relevant description. I want to be treated that way.

[0197] The cathode 404 is formed by covering the EL layer 403. The cathode 404 is the cathode 1 in Embodiment 2. This corresponds to 02. When light is extracted from the anode 401 side, the cathode 404 is made of a material with high reflectivity. It is formed by the cathode 404 being connected to the pad 412, thereby supplying voltage. It can be done.

[0198] The above describes the light-emitting device having an anode 401, an EL layer 403, and a cathode 404 in this embodiment. The lighting device shown is equipped with the light-emitting device. The light-emitting device is a light-emitting device with high luminous efficiency. Therefore, the lighting device in this embodiment can be a lighting device with low power consumption.

[0199] The substrate 400 on which the light-emitting device having the above configuration is formed and the sealing substrate 407 are sealed The lighting device is completed by fixing and sealing it using materials 405 and 406. Either 405 or 406 is acceptable. Also, the inner sealant 406 (Figure 8 (B) (Not shown) A desiccant can also be mixed in, thereby adsorbing moisture in space 408. This allows for improved reliability.

[0200] Furthermore, the pad 412 and a portion of the anode 401 are extended outside the sealing materials 405 and 406. This allows it to be used as an external input terminal. Furthermore, a converter or similar device can be mounted on top of it. An IC chip 420 or similar may be provided.

[0201] As described above, the lighting device described in this embodiment has an EL element as described in Embodiment 1 and Embodiment 2. The light-emitting device described is used, resulting in a highly reliable light-emitting device. Furthermore, This allows for a light-emitting device with low power consumption.

[0202] (Embodiment 5) In this embodiment, the light-emitting device described in Embodiments 1 and 2 is used as a part thereof. Examples of electronic devices to be included will be described. The light-emitting devices described in Embodiment 1 and Embodiment 2 The chair is a reliable light-emitting device with a good lifespan. As a result, this embodiment The electronic device described can be an electronic device having a highly reliable light-emitting part.

[0203] Examples of electronic devices to which the above-mentioned light-emitting device is applied include television equipment (televisions, and (Also called a television receiver), monitors for computers, digital cameras, digital cameras Digital video cameras, digital photo frames, mobile phones (both mobile phones and mobile phone devices) (Examples include) portable game consoles, personal digital assistants, audio playback devices, and large game machines such as pachinko machines. These are some examples. Specific examples of these electronic devices are shown below.

[0204] Figure 9(A) shows an example of a television system. The television system has a housing 710 The display unit 7103 is incorporated into part 1. Also, the housing is connected by the stand 7105. This shows the configuration supporting 7101. The display unit 7103 can display video. The display unit 7103 is capable of displaying the light-emitting devices described in Embodiment 1 and Embodiment 2. It is arranged in a matrix.

[0205] The television equipment can be operated using the control switches on the housing 7101 or a separate remote control. This can be done using the device 7110. The remote control device 7110 has an operation key 7109. This allows you to control the channel and volume, and the video displayed on the display unit 7103 It can be operated. Also, the remote control unit 7110 A display unit 7107 that displays the information output from the unit may also be provided.

[0206] The television system shall consist of a receiver, modem, etc. It can receive television broadcasts, and also communicate via wired or wireless connection through a modem. By connecting to a network, one-way (sender to receiver) or two-way (sender to receiver) communication is possible. It is also possible to communicate information between recipients, or between recipients themselves.

[0207] Figure 9(B1) is a computer, consisting of the main unit 7201, the casing 7202, the display unit 7203, and a key - Includes board 7204, external connection port 7205, pointing device 7206, etc. Furthermore, this computer uses the light-emitting devices described in Embodiment 1 and Embodiment 2. It is manufactured by arranging them in a matrix and using them in the display unit 7203. Figure 9(B1) The computer may take the form shown in Figure 9(B2). The second display unit 7 is used instead of the keyboard 7204 and pointing device 7206. 210 is provided. The second display unit 7210 is a touch panel type, and the second Input is performed by operating the input display shown on the display unit 7210 with a finger or a special pen. This can be done. In addition, the second display unit 7210 can display not only input information but also other images. It is also possible to display an image. Furthermore, the display unit 7203 may also be a touch panel. Because the two screens are connected by a hinge, the screens can get scratched when storing or transporting the device. This also prevents problems such as damage from occurring.

[0208] Figure 9(C) shows an example of a mobile terminal. The mobile phone is incorporated into the housing 7401. In addition to the display unit 7402, there are operation buttons 7403, an external connection port 7404, and a speaker 740 5. It is equipped with a microphone 7406, etc. Note that the mobile phone is the same as in Embodiment 1 and the embodiment. The display unit 7402 is made by arranging the light-emitting devices described in Embodiment 2 in a matrix. It is.

[0209] The mobile terminal shown in Figure 9(C) allows users to input information by touching the display unit 7402 with their fingers or other objects. It can also be configured to allow for making phone calls or composing emails. Operations such as this can be performed by touching the display unit 7402 with a finger or the like.

[0210] The display unit 7402 has three main modes. The first is a display that primarily displays images. The first mode is display mode, the second is input mode which is mainly for inputting information such as characters. The third is display mode. This is a display + input mode, which is a combination of two modes: display mode and input mode.

[0211] For example, when making a phone call or composing an email, the display unit 7402 is used for text input. In this case, the primary text input mode should be used, and you should perform the input operation for the characters displayed on the screen. It is preferable to display a keyboard or number buttons on most of the screen of the display unit 7402. It seems so.

[0212] Furthermore, the mobile device has sensors inside that detect tilt, such as a gyroscope and an accelerometer. By installing the device, the orientation of the mobile terminal (portrait or landscape) is determined, and the screen display of the display unit 7402 is displayed accordingly. The display can be set to switch automatically.

[0213] Furthermore, screen modes can be switched by touching the display unit 7402 or by operating the housing 7401. This is done by operating button 7403. Also, the type of image displayed on display unit 7402 Therefore, it is also possible to switch between them. For example, the image signal displayed on the display unit is a video signal. Switch to display mode if it's data, or to input mode if it's text data.

[0214] Furthermore, in input mode, the signal detected by the optical sensor of the display unit 7402 is detected and displayed If there is no input via touch operation on unit 7402 for a certain period of time, the screen mode will be changed to input mode. You may also control the system to switch from that display mode to a different mode.

[0215] The display unit 7402 can also function as an image sensor. For example, the display unit 74 By touching device 02 with the palm or fingers, the user can be authenticated by capturing images of their palm print, fingerprints, etc. Furthermore, the display unit may have a backlight that emits near-infrared light or a sensing light that emits near-infrared light. Using the appropriate source, it is also possible to image finger veins, palmar veins, and other veins.

[0216] The configuration shown in this embodiment is a combination of the configurations shown in Embodiments 1 to 4 as appropriate. They can be used together.

[0217] As described above, the light-emitting device equipped with the light-emitting device described in Embodiment 1 and Embodiment 2 is suitable for Its range of applications is extremely wide, and this light-emitting device can be applied to electronic equipment in all fields. By using the light-emitting devices described in Embodiment 1 and Embodiment 2, reliability can be improved. You can obtain high-end electronic devices.

[0218] Figure 10(A) is a schematic diagram showing an example of a cleaning robot.

[0219] The cleaning robot 5100 has a display 5101 located on the top and multiple displays located on the sides. It has several cameras 5102, brushes 5103, and operation buttons 5104. However, the underside of the 5100 cleaning robot is equipped with wheels, a suction port, etc. The 5100 robot also includes an infrared sensor, ultrasonic sensor, acceleration sensor, and piezo sensor. It is equipped with various sensors such as optical sensors and gyro sensors. Also, the cleaning robot 5 Unit 100 is equipped with wireless communication means.

[0220] The cleaning robot 5100 moves autonomously, detects the dirt 5120, and uses the suction port located on its underside to... It can then vacuum up the dust.

[0221] Furthermore, the cleaning robot 5100 analyzes images captured by the camera 5102, and detects walls, furniture, or It can determine the presence or absence of obstacles such as steps. Furthermore, image analysis can detect wiring and other obstacles. If an object that may become entangled in brush 5103 is detected, the rotation of brush 5103 will be stopped. can.

[0222] The display 5101 displays information such as the battery level and the amount of dust collected. This is possible. The path taken by the cleaning robot 5100 can be displayed on the display 5101. Good. Also, the display 5101 is a touch panel, and the operation buttons 5104 are on the display. It may also be provided at Ray 5101.

[0223] The cleaning robot 5100 can communicate with portable electronic devices 5140 such as smartphones. Yes, it is possible. Images captured by camera 5102 can be displayed on the portable electronic device 5140. Therefore, the owner of the 5100 cleaning robot can know what's happening in the room even when they're away from home. It is possible to display the information on the display 5101 on portable electronic devices such as smartphones. You can also check it there.

[0224] A light-emitting device according to one aspect of the present invention can be used in a display 5101.

[0225] The robot 2100 shown in Figure 10(B) consists of a computing unit 2110, an illuminance sensor 2101, and a microcontroller. Crossphone 2102, upper camera 2103, speaker 2104, display 2105, It is equipped with a lower camera 2106, an obstacle sensor 2107, and a movement mechanism 2108.

[0226] Microphone 2102 has the function of detecting the user's voice and ambient sounds, etc. Speaker 2104 has the function of emitting sound. Robot 2100 has a microphone Using the 2102 and speaker 2104, communication with the user is possible. It is possible.

[0227] The display 2105 has the function of displaying various information. The robot 2100 is The user can display the desired information on the display 2105. The 2105 may have a touch panel. Also, the display 2105 is removable. It can be any information terminal capable of charging, and by installing it in a fixed position on the robot 2100, And it enables the transfer of data.

[0228] The upper camera 2103 and lower camera 2106 are used to image the area around the robot 2100. It has the ability to detect obstacles. Furthermore, the obstacle sensor 2107 uses the moving mechanism 2108 to detect robot 210 Robot 21 can detect the presence or absence of obstacles in the direction of travel as it moves forward. 00 uses the upper camera 2103, the lower camera 2106 and the obstacle sensor 2107 The light-emitting device according to one aspect of the present invention can recognize its surroundings and move safely. It can be used in display 2105.

[0229] Figure 10(C) shows an example of a goggle-type display. For example, the components include the casing 5000, the display unit 5001, the speaker 5003, and the LED lamp 5004. , connection terminal 5006, sensor 5007 (force, displacement, position, velocity, acceleration, angular velocity, rotational speed) Distance, light, liquid, magnetism, temperature, chemicals, sound, time, hardness, electric field, electric current, voltage, power, (including functions for measuring radiation, flow rate, humidity, gradient, vibration, odor, or infrared radiation), It includes an ICrophone 5008, a display unit 5002, a support unit 5012, an earphone 5013, etc. .

[0230] The light-emitting device according to one aspect of the present invention can be used in the display unit 5001 and the display unit 5002. .

[0231] Figure 11 shows the light-emitting devices described in Embodiments 1 and 2, which are used as lighting devices. This is an example of its use in a desk lamp. The desk lamp shown in Figure 11 consists of a housing 2001 and a light source 20 The device has 02, and the light source 2002 may be the lighting device described in Embodiment 3.

[0232] Figure 12 shows the light-emitting devices described in Embodiment 1 and Embodiment 2 in an indoor lighting device 3 This is an example of its use as 001. The light-emitting devices described in Embodiment 1 and Embodiment 2 Because it is a highly reliable light-emitting device, it can be used to create a highly reliable lighting system. Since the light-emitting devices described in Embodiments 1 and 2 can be made to have a large area, It can be used as a large-area lighting device. Furthermore, in Embodiments 1 and 2 Because the described light-emitting device is thin, it can be used as a miniaturized lighting device. Yes.

[0233] The light-emitting devices described in Embodiments 1 and 2 are used on the windshields and windows of automobiles. It can also be mounted on a dashboard. Figure 13 shows Embodiment 1 and Embodiment 2. This shows one embodiment of using the light-emitting device on the windshield or dashboard of an automobile. Display areas 5200 to 5203 are light-emitting devices as described in Embodiments 1 and 2. This is a display area provided using a vise.

[0234] Display area 5200 and display area 5201 are in an embodiment provided on the windshield of an automobile. This is a display device equipped with the light-emitting device described in Embodiment 1 and Embodiment 2. Embodiment 1 The light-emitting device described in Embodiment 2 is made by fabricating the anode and cathode with light-transmitting electrodes. This allows the display device to be made transparent, allowing the other side to be seen through, creating a so-called see-through display. Yes, it's possible. If it's a see-through display, it can be installed on a car's windshield. It can be installed without obstructing the view. Note that it requires transistors for operation, etc. When providing an organic transistor, an organic transistor made of organic semiconductor material or a transistor made of oxide semiconductor material may be used. It is best to use a transmissive transistor, such as a transistor.

[0235] The display area 5202 is provided in the pillar portion as described in Embodiments 1 and 2. This is a display device equipped with an optical device. The display area 5202 is an imaging device provided on the vehicle body. By displaying images from the steps, the view obstructed by the pillars can be compensated for. Similarly, the display area 5203 located on the dashboard is obstructed by the vehicle body. The field of view is obscured by displaying images from an imaging device installed on the outside of the vehicle, thereby reducing blind spots. This can supplement the unseen parts and enhance safety. Therefore, safety checks can be performed more naturally and without any sense of unease.

[0236] The display area 5203 can provide various types of information. The display can be customized to the user's preferences. The displayed items and layout can be changed as needed. Note that this information is displayed in area 5. It can also be provided in display areas 200 to 5202. Area 5203 can also be used as a lighting device.

[0237] Figures 14(A) and (B) also show a foldable portable information terminal 5150. The portable information terminal 5150 consists of a housing 5151, a display area 5152, and a bendable portion 515 It has 3. Figure 14(A) shows the portable information terminal 5150 in its unfolded state. Figure 14( B) shows the portable information terminal in its folded state. The portable information terminal 5150 has a large display area Despite having a 5152mm field of view, it folds up compactly and is highly portable.

[0238] The display area 5152 can be folded in half by the bending portion 5153. Bending portion 515 3 consists of an expandable member and multiple support members, and when folded, the expandable The member stretches, and the bent portion 5153 has a radius of curvature of 2 mm or more, preferably 3 mm or more. It folds up.

[0239] Note that the display area 5152 is a touch panel (input / output) equipped with a touch sensor (input device). It may also be a device. The light-emitting device according to one aspect of the present invention can be used in the display area 5152. Cut.

[0240] Figures 15(A) to (C) also show a foldable portable information terminal 9310. Figure 15 (A) shows the portable information terminal 9310 in its unfolded state. Figure 15(B) shows the unfolded state or This shows the portable information terminal 9310 in an intermediate state, transitioning from one folded state to the other. Figure 15(C) shows the folded state of the personal digital assistant 9310. Personal digital assistant 9310 It offers excellent portability when folded and a seamless, wide display area when unfolded. This provides excellent readability in the display.

[0241] The display panel 9311 is supported by three housings 9315 connected by hinges 9313. The display panel 9311 is a touch panel equipped with a touch sensor (input device). It may also be an input / output device. In addition, the display panel 9311 is connected via the hinge 9313. By bending the two housings 9315, the mobile information terminal 9310 is unfolded. It can be reversibly transformed from a folded state. A light-emitting device according to one aspect of the present invention It can be used with the display panel 9311. [Examples]

[0242] In this embodiment, a light-emitting device 1 and a comparative light-emitting device 1 according to one aspect of the present invention are used. The manufacturing method and impedance spectroscopy measurement results are described. Light-emitting device 1 and comparison light-emitting device The structural formulas of the organic compounds used in step 1 are shown below.

[0243] [ka]

[0244] (Method for fabricating light-emitting device 1) First, indium tin oxide (ITSO) containing silicon oxide is sputtered onto a glass substrate. A film was deposited using the 2-phase method to form the anode 101. The film thickness was 70 nm, and the electrode area was 2 The dimensions were set to mm x 2 mm.

[0245] Next, as a pretreatment for forming a light-emitting device on the substrate, the substrate surface is washed with water, and 2 After firing at 0°C for 1 hour, UV ozone treatment was performed for 370 seconds.

[0246] Then, 10 -4 A substrate is introduced into a vacuum deposition apparatus where the internal pressure is reduced to approximately Pa, and then vacuum deposition is performed. After vacuum firing at 170°C for 30 minutes in the heating chamber of the apparatus, the substrate is left for approximately 30 minutes. It was allowed to cool.

[0247] Next, the substrate on which the anode 101 is formed is positioned so that the surface on which the anode 101 is formed faces downwards. The substrate is fixed to a substrate holder provided inside the vapor deposition apparatus, and vapor deposition is carried out on the anode 101 using resistance heating. N,N-bis(4-biphenyl)-6-phenyl represented by the above structural formula (i) is obtained by the bonding method. Benzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf) and AL D-MP001Q (Analysis Workshop Co., Ltd., Material serial number: 1S20180314) , such that the weight ratio is 1:0.1 (=BBABnf:ALD-MP001Q), 10n A hole injection layer 111 was formed by co-deposition. Note that ALD-MP001Q is an acceptor. It is an organic compound that possesses properties.

[0248] Next, BBABnf is added to the hole injection layer 111 as the first hole transport layer 112-1. After deposition to a size of nm, the second hole transport layer 112-2 is formed using the above structural formula (ii). Represented as 3,3'-(naphthalene-1,4-diyl)bis(9-phenyl-9H-cal) A hole transport layer 112 is formed by depositing a bazole (abbreviated as PCzN2) to a thickness of 10 nm. Success. Furthermore, the second hole transport layer 112-2 also functions as an electron blocking layer.

[0249] Next, the 9-(1-naphthyl)-10-[4-(2-naphthyl] represented by the above structural formula (iii) [Phthyl)phenyl]anthracene (abbreviation: αN-βNPAnth) and (iv) 3,10-Bis[N-(9-phenyl-9H-carbazol-2-yl)-N-phenyl [amino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10PCA) 2Nbf(IV)-02) and a weight ratio of 1:0.015 (=αN-βNPAnth:3, A 25nm co-deposited layer (10PCA2Nbf(IV)-02) is formed to create the light-emitting layer 113. I did it.

[0250] Subsequently, on the light-emitting layer 113, 2-{4-[9,10-di(na) represented by the above structural formula (v) is applied. Phthalen-2-yl)-2-anthryl]phenyl}-1-phenyl-1H-benzoimi Dazole (abbreviation: ZADN) and 8-hydroxyquinolinate represented by the above structural formula (vi) - Lithium (abbreviation: Liq) (manufactured by Chemipro Chemical Co., Ltd. (serial number: 181201)) After co-depositing 12.5 nm with a volume ratio of 0.7:1 (=ZADN:Liq), the weight ratio A 12.5 nm co-deposited layer was created so that the ratio was 1:0.7 (=ZADN:Liq), and the electron transport layer 11 Formed 4.

[0251] After forming the electron transport layer 114, Liq is deposited to a thickness of 1 nm to form the electron injection layer 1 Forming 15, and then depositing aluminum to a thickness of 200 nm to create a cathode The light-emitting device 1 of this embodiment was fabricated by forming 102.

[0252] (Method for fabricating comparative light-emitting device 1) Comparative light-emitting device 1 uses the above structural formula (vi) to represent αN-βNPAnth in the light-emitting layer 113. i) 7-[4-(10-phenyl-9-antryl)phenyl]-7H-gibe Replace with nz[c,g]carbazole (abbreviation: cgDBCzPA) and move the electron transport layer 114 upwards. The structural formula (viii) is 2-[3'-(dibenzothiophen-4-yl)bife [Nyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II) After depositing ) at a 15 nm layer, the 2,9-di(2-naphthyl)- represented by the above structural formula (ix) 4,7-diphenyl-1,10-phenanthroline (abbreviation: NBPhen) vaporized to 10 nm Aside from the attachment process, the device was fabricated in the same manner as light-emitting device 1.

[0253] The element structures of light-emitting device 1 and comparative light-emitting device 1 are summarized in the table below.

[0254] [Table 3]

[0255] Here, the HOMO level, LUMO level, and electric field strength of the organic compound used in this example [ The following table summarizes the electron mobility at a square root of 600 [V / cm].

[0256] [Table 4]

[0257] These light-emitting devices are placed in a glove box under a nitrogen atmosphere, and the light-emitting devices are exposed to the atmosphere. The process of sealing the element with a glass substrate to prevent exposure to sunlight (applying a sealing material around the element and sealing it) After UV treatment and heat treatment at 80°C for 1 hour, the initial characteristics of these light-emitting devices are determined. And reliability measurements were performed. The measurements were taken at room temperature. Light-emitting device 1 and ratio Comparison of light-emitting device 1: 1000 cd / m² 2 Table 5 shows the main characteristics of the vicinity.

[0258] [Table 5]

[0259] As shown in Table 5, the light-emitting device 1 and comparative light-emitting device 1, which are embodiments of the present invention, exhibit good initial It was found to be a blue light-emitting device with specific characteristics.

[0260] Furthermore, the current density is 50 mA / cm². 2 The graph shows the change in brightness with respect to operating time. As shown in Figure 20, a light-emitting device 1 is a light-emitting device according to one aspect of the present invention. The brightness increases after operation, reaching a level higher than the initial brightness, and then gradually decreases. This can be seen. In other words, it has a maximum point in the degradation curve. From this, it can be seen that the initial brightness is particularly important. This significantly improves the drive life, which is based on a low degradation state of about 2-5%. came.

[0261] Next, impedance spectroscopy (IS measurement) is performed on light-emitting device 1 and comparison light-emitting device 1. The following was performed: A small sinusoidal voltage signal [V=V0exp(iωt)] was applied to the light-emitting device. The current amplitude of the response current signal [I=I0exp{i(ωt+φ)}] and the position of the input signal The impedance (Z=V / I) was determined from the phase difference. The voltage changed from high frequency to low frequency. When applied to the element, it separates components with various relaxation times that contribute to impedance. It can be measured.

[0262] The frequency of the applied voltage signal is used as a parameter, and the resulting impedance is displayed on the complex plane. This is called a Nyquist plot. By determining the impedance (Z), the basic The fundamental transfer function, including admittance (Y), modulus (M), and permittivity (ε), is determined. It is possible.

[0263] In this example, an impedance (Z) plot showing the resistance component from the real axis, and capacitance We analyzed the light-emitting device using a modulus (M) plot, which shows the reciprocal of the fraction.

[0264] Measurements were taken using the Biologic SP-300 Advance high-performance electrochemical measurement system. The procedure was performed using a microcurrent measurement cable on the model.

[0265] The Z-plots for light-emitting device 1 and comparative light-emitting device 1 are shown in Figure 21(A)(B). 21(A) and (B) both have a frequency range of 1MHz to 3MHz, an AC voltage of 100mV, and applied power Measurements were taken at a voltage of 2.5V. Furthermore, the operating time of the element after driving was measured for the light-emitting device. 1 is 50mA / cm 2 The device used had a lifespan of 670 hours, while the comparative light-emitting device 1 had a lifespan of 380 hours. .

[0266] As shown in Figure 21(A), the light-emitting device 1 according to one aspect of the present invention is such that the device after being driven is the same as the device before being driven. It can be seen that the resistance is lower than that of the vice. On the other hand, the conventional element, the comparative light emission device In chair 1, as shown in Figure 21(B), the resistance of the device after driving is slightly lower than that of the device before driving. I noticed it had grown bigger.

[0267] Furthermore, Figure 22 shows a current density of 50 mA / cm². 2 Voltage relative to operating time under certain conditions The following changes were observed. As shown in Figure 22, the light-emitting device 1, which is a light-emitting device according to one aspect of the present invention, When driven under the condition of constant current density, the drive voltage decreases, and the drive is The results are consistent with IS measurement results, which suggest a decrease in resistance.

[0268] Furthermore, in the conventional comparative light-emitting device 1, the drive voltage increases as it is driven. This also showed results consistent with IS measurements. Conventional light-emitting devices, in this way, Under constant density conditions, the drive voltage almost always tends to increase with operation. Yes, the decrease in drive voltage associated with the operation is a phenomenon characteristic of the light-emitting device according to one aspect of the present invention. .

[0269] Next, Figure 23 shows the M-plot of light-emitting device 1. The graph shape before and after operation. The shapes were different, and it was found that the modulus changed before and after the drive.

[0270] Next, the equivalent circuit analysis software ZView (Scribner Associates) The fitting was done by es (Scrivner Associates / USA), and this light-emitting device Vice's equivalent circuit can be represented by four RC parallel circuits and one series resistor, as shown in Figure 18. It was found that this is possible. Note that the numerical values ​​in the M-plot were separated by fitting, etc. This indicates the location where the resistance component of the valence circuit is present.

[0271] Next, Figure 19 shows a graph plotting the values ​​of the separated resistance components before and after driving. From this, it can be seen that the resistance of R2 after driving is reduced by more than an order of magnitude compared to the resistance before driving. mosquito That's it.

[0272] Therefore, we determine which layer of the light-emitting device 1 each of these resistive components corresponds to. We fabricated light-emitting devices (light-emitting device 2 to light-emitting device 8) with varying film thicknesses for each layer. This was confirmed by measuring IS. These light-emitting devices are located in the electron transport layer 114. Except for the configuration and the film thickness of the parts shown in bold in the table below, it has the same configuration as light-emitting device 1. Regarding the electron transport layer 114, the electron transport layer 114 of the light-emitting device 1 is 12.5n The first electron transport layer 114-1 and 12.5 nm of ZADN:Liq (=0.7:1) The second electron transport layer 114-2 had a stacked structure of ZADN:Liq (=1:0.7). Light-emitting devices 2 through 8 are 25nm, 35nm, 45nm and 55nm It is formed with one ZADN:Liq (=1:1) layer.

[0273] [Table 6]

[0274] IS measurements were performed on light-emitting devices 2 through 8, and the M was created using the obtained results. The plots are shown in Figures 24 to 26. Light-emitting devices with varying film thickness of electron transport layer 114. Figure 24(A) shows the M-plots of light-emitting devices 3 through 5 and the reference light-emitting device 2. ) Light-emitting devices 6 and 7, in which the film thickness of the light-emitting layer 113 is varied, and reference Figure 25(A) shows the M plot of the light-emitting device 2, which is the first hole transport layer 112-1 The M-plots of light-emitting device 8 with varying film thickness and the reference light-emitting device 2 are shown. This is shown in Figure 26(A).

[0275] From Figures 24(A) to 26(A), by changing the film thickness of each layer, the M plot can be obtained. It can be seen that the shape also changes. Figures 24(B) to 26(B) show each light-emitting device. The resistance of the circuit corresponds to the resistance component R obtained from fitting using ZView. This plot shows the values ​​plotted at intervals from 1 to R5.

[0276] As shown in Figures 24 to 26, in light-emitting devices in which the thickness of the electron transport layer 114 is changed, R2 In a light-emitting device in which the thickness of the light-emitting layer 113 is changed, the resistive component of R1 is the first In light-emitting devices in which the thickness of the hole transport layer 112-1 is varied, the resistive component of R3 is different. It can be seen that it is changing. Below is a light-emitting device according to one embodiment of the present invention, as shown in Figure 18. In the equivalent circuit, R1 is the light-emitting layer, R2 is the electron transport layer, and R3 is the first hole transport layer. This led to the conclusion that the remaining R4 layer is the second hole transport layer.

[0277] Based on the above, the resistance component R2, whose resistance changes before and after driving, is a component originating from the electron transport layer 114. It was found that this was the case.

[0278] Thus, the light-emitting device 1, which is a light-emitting device according to one aspect of the present invention, provides light emission with a good lifespan. A device in which the overall resistance of the light-emitting device decreases after operation compared to before operation. It was found that this was due to a decrease in the resistance of the electron transport layer 114. It was found to be that.

[0279] These results indicate that when the light-emitting device 1 is driven, the resistance of the electron transport layer 114 decreases. As a result, the carriers (electrons) become more responsive, and spread to a portion of the electron transport layer 114. The end of the recombination region moves towards the light-emitting region. This contributes to light emission in the electron transport layer. This makes it possible to convert the recombination energy that would otherwise be deactivated into light emission. Therefore, it is thought that an increase in brightness occurs as shown in Figure 20.

[0280] Thus, the light-emitting device according to one aspect of the present invention is a light-emitting device with a good lifespan. can. [Examples]

[0281] In this embodiment, an electric current-carrying (light-emitting device) can be used in the electron transport layer 114. This section describes an example of a material whose resistance decreases when it is moved.

[0282] Materials whose resistance decreases when the current is passed through them include alkali metals or alkaline earth elements. Elemental metal organometallic complexes, or organic compounds with electron transport properties, and alkali metals or A mixed material containing earth metal compounds of rucalis is suitably used. In this example, , as an organic compound with electron transport properties, 2-phenyl-3-{4-[10-(3-pyridyl [Lu)-9-anthryl]phenyl}quinoxaline (abbreviation: PyA1PQ), alkali metal Alternatively, the calculation results when Liq is used as the organometallic complex of alkaline earth metals. show.

[0283] First, in a film in which PyA1PQ and Liq are mixed in a weight ratio of 1:1, the Liq We performed calculations on the ease of polymer formation. The calculations were performed using classical molecular dynamics (molecules). The calculation was performed using lar dynamics. Specifically, the weight ratio was adjusted to 1:1. Then, place molecules into the cell such that the molar ratio of PyA1PQ to Liq is 18:82. First, the cell is compressed at high temperature and pressure, then the pressure is reduced to atmospheric pressure, and the temperature is reduced to room temperature. By reducing the temperature, the model becomes mitigated, and by mitigating the conditions within the cell, it enters an amorphous state. The process was carried out. Subsequently, the condensation state of the molecules within the cell was examined, and Liq dimers and trimers were found. Such aggregates and hexameric clusters were extracted. From this, it was found that room temperature and atmospheric conditions This suggests that Liq polymers are easily formed even in this state.

[0284] Next, we will examine the extent to which Liq is stabilized by polymerizing from its elemental form. Then, structural optimization was performed and evaluated using first-principles calculations. The structural optimization calculations were performed using G Using Aussian 09, Revision E.01, and RB3 as the basis function. The evaluation was performed under vacuum conditions using LYP / 6-311g(d,p). Energy levels when each polymer is composed of individual Liq particles versus when it is composed of that polymer. By comparing the two, we calculate the amount of energy stabilized by the polymerization, and then... The value of ghee is divided by the number of Liqs to calculate the stabilized energy per Liq. The calculations and evaluations were performed for dimers, trimers, tetramers, hexamers, and octamers of Liq. The test was performed on the body. The results are shown in Figure 27.

[0285] From the graph in Figure 27, it can be seen that Liq is most stable when it is in the form of a hexamer. The stabilized energy per Liq atom in the mixture was approximately 1.54 eV. This indicates that in Liq, the hexameric structure is stable and preferentially formed. I was persuaded. Furthermore, the stabilization energy from the tetramer to the octamer of Liq obtained by calculation is large Since no significant difference is observed, it is thought that polymers of tetramers or larger are easily formed.

[0286] Therefore, Liq used in the electron transport layer drives the light-emitting device (conducts current). It is thought that by applying an electric current, a polymer is gradually formed. Materials with reduced resistance are those containing alkali metal or alkaline earth metal organometallic complexes. As polymers are formed, electron mobility improves, and resistance decreases.

[0287] In one embodiment of the present invention, the light-emitting device reaches the electron transport layer in the initial stages of operation. Although the carrier balance is adjusted in such a way, by continuing to drive, the electron transport layer Clusters of organometallic complexes of potassium metals or alkaline earth metals are formed, and electron mobility increases. As it rises, the carrier balance changes. As a result, the recombination region is contained within the light-emitting layer. This process increases brightness, resulting in a light-emitting device with low initial degradation and a long lifespan. It is possible.

[0288] <Reference example 1> In this reference example, the HOMO level, LUMO level, and electron transfer of the organic compounds used in each example are shown. I will now explain how to calculate the degree of motion.

[0289] HOMO and LUMO levels are calculated based on cyclic voltammetry (CV) measurements. It is possible.

[0290] The measuring device used is an electrochemical analyzer (manufactured by BAS Corporation, model number: ALS model). A 600A or 600C was used. The solution used in the CV measurement was dehydrated dimethyl as the solvent. Aldrich Formamide (DMF) (manufactured by Aldrich Co., Ltd., 99.8%, catalog number; 227) Using 05-6), the supporting electrolyte is tetra-n-butylammonium perchlorate (nB u4NClO4) (manufactured by Tokyo Chemical Co., Ltd., catalog number: T0836) 100 mmol / Dissolve to a concentration of L, and then dissolve the sample to be measured to a concentration of 2 mmol / L. It was prepared by dissolving it. Furthermore, a platinum electrode (manufactured by BAS Corporation, PT) was used as the working electrode. E Platinum electrode) is used as an auxiliary electrode, and platinum electrode (manufactured by B.A.S. Co., Ltd., for VC-3 P A counter electrode (5 cm) is used, and an Ag / Ag+ electrode (B.A.A.E.) is used as the reference electrode. A RE7 non-aqueous solvent reference electrode manufactured by S Corporation was used. The measurements were taken at room temperature (20°C). The measurements were performed at 25°C. The scan speed during CV measurement was standardized to 0.1V / sec. The oxidation potential Ea [V] and reduction potential Ec [V] were measured relative to the irradiated electrode. Ea is the oxidation- The intermediate potential of the reduction wave was used, and Ec was set as the intermediate potential of the reduction-oxidation wave. Here, the values ​​used in this embodiment The potential energy of the reference electrode relative to the vacuum level is -4.94 [eV]. Since it is known that the HOMO level [eV] = -4.94 - Ea, the LUMO level [eV The HOMO level and LUMO level can be determined from the equation ] = -4.94 - Ec. It is possible.

[0291] Electron mobility is measured by impedance spectroscopy. It can be measured using the IS method.

[0292] The carrier mobility of EL materials is measured using transient photocurrent (Time-of-flight:T) spectroscopy. OF method and space-charge-limited current Methods such as the SCLC method, which is derived from the IV characteristics of nt (SCLC), have been known for a long time. The TOF method requires a sample with a considerably thicker film thickness compared to actual organic EL elements. The LC method has drawbacks such as not being able to obtain the electric field strength dependence of carrier mobility. Because the thickness of the organic film required for measurement is thin, around several hundred nanometers, even a relatively small amount of EL material can be used. Its key features include the ability to deposit thin films and measure mobility with film thicknesses close to those of actual EL elements. Therefore, the electric field strength dependence of carrier mobility can also be obtained.

[0293] In the IS method, a small sinusoidal voltage signal (V=V0[exp(jωt)]) is applied to the EL element. The current amplitude of the response current signal (I=I0exp[j(ωt+φ)]) and the phase of the input signal From the difference, we can find the impedance of the EL element (Z=V / I). Low frequency voltage from high frequency voltage. By changing it to this extent and applying it to the element, it has various relaxation times that contribute to the impedance. The components can be separated and measured.

[0294] Here, the admittance Y (=1 / Z), which is the reciprocal of impedance, is given by the following equation (1): It can be expressed in terms of conductance G and susceptance B.

[0295]

number

[0296] Furthermore, the single-charge injection model shows that, respectively, Equations (2) and (3) can be calculated. Here, g (equation (4)) is the differential conductor. This is tance. In the formula, C is capacitance, θ is ωt, and the travel angle is... ω represents the angular frequency. t is the travel time. The analysis involves the current equation, Poisson's equation, and current continuity. The equation used ignores the existence of diffusion current and trap levels.

[0297]

number

[0298] The -ΔB method is a method for calculating mobility from the frequency characteristics of capacitance. The ωΔG method is a method for calculating mobility from the frequency characteristics of a device.

[0299] In practice, first, a measurement element is fabricated using the material whose electron mobility is to be determined. The element used is designed so that only electrons flow as carriers. The equation is shown in Figure 28. Note that in this specification, mobility is calculated from the frequency characteristics of capacitance. I will now explain the method (-ΔB method).

[0300] The structure of the measuring element fabricated for this measurement is as shown in Figure 28, consisting of an anode 201 and a cathode 2 Between 02 there are a first layer 210, a second layer 211, and a third layer 212. Electron mobility The desired material can be used as the material for the second layer 211. In this case, ZADN and Liq 0 This explanation will use an example of measuring the electron mobility of a co-evaporated film with a weight ratio of 0.5:0.5. Specific configuration examples are summarized in the table below.

[0301] [Table 7]

[0302] Impedance measurement is performed by applying a DC voltage in the range of 5.0V to 9.0V while simultaneously measuring the AC voltage. Measurements were taken under the conditions of 70mV and a frequency of 1Hz to 3MHz. The impedance obtained here Capacitance is calculated from admittance (equation (1) above), which is the reciprocal of dance. Figure 29 shows the frequency characteristics of the calculated capacitance C at an applied voltage of 7.0V.

[0303] The frequency characteristics of capacitance C are determined by the spatial charge of carriers injected by a small voltage signal. This is obtained when the load cannot fully follow the minute AC voltage, resulting in a phase difference in the current. Here, the travel time of the carriers in the membrane is the time T it takes for the injected carriers to reach the counter electrode. It is defined and expressed by the following equation (5).

[0304]

number

[0305] The negative susceptance change (-ΔB) is the value obtained by multiplying the capacitance change -ΔC by the angular frequency ω (-ωΔ). This corresponds to C). Its lowest frequency peak frequency is f'. max (=ω max ( / 2π) and run From equation (3), the following relationship (6) can be derived between row time T and row time.

[0306]

number

[0307] Figure 3 shows the frequency characteristics of -ΔB calculated from the above measurements (i.e., when the DC voltage is 7.0V). The lowest frequency peak frequency f' is obtained from Figure 30.max This is indicated by the arrow in the diagram. did.

[0308] f' obtained from the above measurements and analysis max Therefore, the travel time T can be determined (using the above formula ( 6) See above. From equation (5), we can determine the electron mobility at a voltage of 7.0V in this case. This can be done. By performing similar measurements in the DC voltage range of 5.0V to 9.0V, each voltage can be determined. Since electron mobility can be calculated at (electric field strength), the dependence of mobility on electric field strength can also be measured.

[0309] Using the calculation methods described above, the final electron mobility of each organic compound depends on the electric field strength. Figure 31 shows that the square root of the electric field strength [V / cm] read from the figure is 600 [V / cm]. 1 / 2 Table 9 shows the electron mobility values ​​for each of these conditions.

[0310] [Table 8]

[0311] As described above, it is possible to calculate electron mobility. For detailed measurement methods, please refer to the following. Takayuki Okachi et al. "Japanese Journal of Applied Physics” Vol. 47, No. 12, 2008, Please refer to pp. 8965-8972.

[0312] <Reference example 2> In this reference example, the 2-phenyl-3-{4-[10-(3-pyridinyl) used in Example 2 Regarding the synthesis method of [Lu-9-antryl]phenyl}quinoxaline (abbreviation: PyA1PQ) Let me explain. The structure of PyA1PQ is shown below.

[0313] [ka]

[0314] 0.74g of 3-(10-bromo-9-anthryl)pyridine (2) in a 50mL three-necked flask. 0.2 mmol), tri(ortho-tril)phosphine 0.26 g (0.85 mmol), 4-(3-phenylquinoxaline-2-yl)phenylboronic acid 0.73g (2.3mm) 1.3g (9.0 mmol) potassium carbonate aqueous solution, ethylene glycol dimethyl Add 40 mL of ether (DME) and 4.4 mL of water. Stir this mixture under reduced pressure. The flask was then degassed and the contents were replaced with nitrogen.

[0315] Add 65 mg (0.29 mmol) of palladium(II) acetate to the mixture in this flask. The mixture was stirred at 80°C for 11 hours under a nitrogen stream. After stirring, water was added to the mixture in the flask. Extraction was performed with Luen. The resulting extract was washed with saturated saline solution and dried with magnesium sulfate. This was then filtered naturally, and the filtrate was concentrated to obtain an oily substance. The obtained oily substance was then placed in silica gel. Column chromatography was performed twice, once with chloroform and once with toluene:ethyl acetate in a 5:1 ratio. The product was purified and recrystallized with toluene / hexane to obtain a yellow solid of the target product in a yield of 0.43 g and 36% yield. It was obtained as a percentage. The synthesis scheme is shown in the following formula.

[0316] [ka]

[0317] The resulting yellow solid (0.44 g) was purified by sublimation using the train sublimation method. Purification was performed at a pressure of 10 Pa, an argon flow rate of 5.0 mL / min, and 260°C for 18 hours. The procedure was carried out under thermal conditions. After sublimation purification, 0.35 g of the target substance was obtained as a yellow solid with a recovery rate of 79%.

[0318] Furthermore, nuclear magnetic resonance spectroscopy of the yellow solid obtained from the above reaction ( 1 Analysis results by 1H-NMR The results are shown below. From these results, in this embodiment, PyA1PQ represented by the above structural formula It was found that this was obtained.

[0319] 1 H NMR(CDCl3,300MHz):δ=7.37-7.50(m,9H), 7 .56-7.78(m,9H), 7.82-7.86(m,3H), 8.24-8.30 (m,2H), 8.75(dd,J=1.8Hz,0.9Hz,1H), 8.84(dd (J=4.8Hz, 1.8Hz, 1H). [Explanation of symbols]

[0320] 101 Anode 102 Cathode 103 EL layer 111 Hole injection layer 112 Hole transport layer 112-1 First hole transport layer 112-2 Second hole transport layer 113 Emitting layer 113-1 Recombination region 114 Electron transport layer 114-1 First electron transport layer 114-2 Second electron transport layer 115 Electron injection layer 116 Charge generation layer 117 P type layer 118 Electron relay layer 119 Electron injection buffer layer 120 Non-luminescent recombination region 201 Anode 202 Cathode 210 First layer 211 Second Layer 212 The third layer 400 circuit boards 401 Anode 403 EL layer 404 Cathode 405 sealant 406 Sealant 407 Sealing substrate 408 Space 412 pads 420 IC chips 501 Anode 502 Cathode 511 First light-emitting unit 512 Second light-emitting unit 513 Charge generation layer 601 Drive circuit section (source line drive circuit) 602 pixel section 603 Drive circuit section (gate wire drive circuit) 604 Sealing substrate 605 Sealant 607 Space 608 Wiring 609 FPC (Flexible Printed Circuit) 610 element substrate 611 Switching FET 612 Current-Controlled FET 613 Anode 614 Insulators 616 EL layer 617 Cathode 618 Light-emitting devices 951 circuit board 952 Electrode 953 Insulating layer 954 Partition layer 955 EL layer 956 Electrode 1001 circuit board 1002 Underlying insulating film 1003 Gate Insulator 10:06 Guard Station 1007 🙏 1008 Gate 1020 First interlayer insulating film 1021 Second interlayer insulating film 1022 Electrode 1024W anode 1024R Anode 1024G anode 1024B Anode 1025 Bulkhead 1028 EL layer 1029 Cathode 1031 Sealing substrate 1032 Sealant 1033 Transparent base material 1034R Red colored layer 1034G Green colored layer 1034B Blue colored layer 1035 Black Matrix 1036 Overcoat layer 1037 Third interlayer insulating film 1040 pixel section 1041 Drive circuit section 1042 Peripheral area 2001 cabinet 2002 light source 2100 Robots 2110 Arithmetic equipment 2101 Illuminance Sensor 2102 Microphone 2103 Top Camera 2104 Speaker 2105 Display 2106 Lower Camera 2107 Obstacle Sensor 2108 Moving mechanism 3001 Lighting device 5000 cabinets 5001 Display section 5002 Second display unit 5003 Speaker 5004 LED Lamp 5006 Connection terminal 5007 Sensor 5008 Microphone 5012 Support part 5013 Earphones 5100 Cleaning Robot 5101 Display 5102 Camera 5103 Brush 5104 Operation Buttons 5150 Mobile Information Terminal 5151 enclosure 5152 Display area 5153 Bent section 5120 Garbage 5200 display area 5201 Display area 5202 Display area 5203 Display area 7101 enclosure 7103 Display section 7105 Stand 7107 Display section 7109 Operation Keys 7110 Remote Control Unit 7201 Main Unit 7202 enclosure 7203 Display section 7204 Keyboard 7205 External connection port 7206 Pointing device 7210 Second display unit 7401 enclosure 7402 Display section 7403 Operation Buttons 7404 External connection port 7405 Speaker 7406 Microphone 9310 Mobile Information Terminal 9311 Display Panel 9313 Hinge 9315 enclosure

Claims

1. It has an anode and a cathode, Between the anode and the cathode, there is a hole injection layer, a hole transport layer, a light-emitting layer, and an electron transport layer. The hole injection layer is located between the anode and the light-emitting layer. The hole transport layer is located between the hole injection layer and the light-emitting layer. The electron transport layer is located between the light-emitting layer and the cathode. The hole injection layer comprises a first substance and a second substance. The hole transport layer has a third substance, The first substance is an organic compound that has hole transport properties and whose HOMO level is between -5.7 eV and -5.4 eV. The HOMO level is a value obtained by cyclic voltammetry measurement. The second substance is a substance that exhibits electron-accepting properties with respect to the first substance, The first and third substances have the same skeleton, which comprises one of the following: a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton. A light-emitting device in which the electron transport layer is made of a material whose resistance decreases when an electric current is passed through it.

2. In claim 1, A light-emitting device in which the material whose resistance decreases when the aforementioned current is passed through it contains an organometallic complex of an alkali metal or alkaline earth metal.

3. In claim 1, A light-emitting device comprising an organic compound having electron-transporting properties and an organometallic complex of an alkali metal or alkaline earth metal, wherein the material whose resistance decreases when the current is passed through it.

4. In claim 2 or claim 3, A light-emitting device in which the organometallic complex of an alkali metal or alkaline earth metal is a metal complex having a ligand containing nitrogen and oxygen, and an alkali metal or alkaline earth metal.

5. In any one of claims 2 to 4, A light-emitting device in which the organometallic complex of an alkali metal or alkaline earth metal is a metal complex having a ligand containing an 8-hydroxyquinolinate structure and a monovalent metal ion.

6. In any one of claims 2 to 4, A light-emitting device in which the organometallic complex of an alkali metal or alkaline earth metal is a lithium complex having a ligand containing an 8-hydroxyquinolinate structure.

7. In any one of claims 2 to 6, The electron transport layer comprises a first layer and a second layer, The first layer is located between the light-emitting layer and the second layer. The second layer is located between the first layer and the cathode. The concentration of the alkali metal or alkaline earth metal organometallic complex contained in the first layer is different from the concentration of the alkali metal or alkaline earth metal organometallic complex contained in the second layer. A light-emitting device in which the organometallic complex contained in the first layer and the organometallic complex contained in the second layer are the same substance.

8. In claim 7, A light-emitting device in which the concentration of an alkali metal or alkaline earth metal organometallic complex contained in the first layer is higher than the concentration of an alkali metal or alkaline earth metal organometallic complex contained in the second layer.

9. In any one of claims 1 to 8, The first substance is a light-emitting device having at least one of a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton.

10. In any one of claims 1 to 9, A light-emitting device in which the second substance is an organic compound.

11. In any one of claims 1 to 10, The light-emitting layer comprises a host material and a light-emitting substance. The aforementioned light-emitting material is a light-emitting device that emits blue fluorescence.

12. An electronic device comprising a light-emitting device according to any one of claims 1 to 11, and a sensor, an operating button, a speaker, or a microphone.

13. A light-emitting device comprising a light-emitting device according to any one of claims 1 to 11, and a transistor or a substrate.

14. A lighting device comprising a light-emitting device according to any one of claims 1 to 11, and a housing.

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