Light-emitting device, electronic appliance, light-emitting apparatus, and illumination apparatus

Abstract

To provide a light-emitting device with high luminous efficiency.SOLUTION: An electronic device includes an anode, a cathode, and an EL layer positioned between the anode and the cathode. The EL layer has a first layer, a second layer, and a third layer. The first layer is positioned between the anode and the second layer. The third layer is positioned between the second layer and the cathode. The first layer includes an organic compound with a hole transport property. The third layer includes an organic compound with an electron transport property. The organic compound with the hole transport property and the organic compound with the electron transport property have a specific structure. A normal light refractive index of each of the organic compound with the hole transport property and the organic compound with the electron transport property in light at a wavelength of 455 nm or more and 465 nm or less is 1.5 or more and 1.75 or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One embodiment of the present invention relates to an organic compound, a light-emitting element, a light-emitting device, a display module, a lighting module, a display device, a light-emitting device, an electronic device, a lighting device, and an electronic device. Note that one embodiment of the present invention is not limited to the above technical field. The technical field of one embodiment of the invention disclosed in this specification etc. relates to an object, a method, or a manufacturing method. Alternatively, one embodiment of the present invention relates to a process, a machine, manufacture, or a composition of matter. Therefore, more specific examples of the technical field of one embodiment of the present invention disclosed in this specification include semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, lighting devices, power storage devices, memory devices, imaging devices, driving methods thereof, and manufacturing methods thereof. [Background technology]

[0002] Light-emitting devices (organic EL devices) that utilize electroluminescence (EL) using organic compounds are becoming more and more common. The basic structure of these light-emitting devices is a pair of electrodes sandwiching an organic compound layer (EL layer) containing a light-emitting material between them. By applying a voltage to this device, carriers are injected, and the recombination energy of these carriers is utilized to emit light from the light-emitting material.

[0003] Since such light-emitting devices are self-luminous, when used as display pixels, they offer advantages such as higher visibility and no need for backlighting compared to liquid crystal displays, making them particularly suitable for flat panel displays. Another major advantage of displays using such light-emitting devices is that they can be fabricated to be thin and lightweight. Another feature is their extremely fast response time.

[0004] Furthermore, these light-emitting devices can emit light continuously in two dimensions, making it possible to obtain surface light emission. This is a feature that is difficult to obtain with point light sources such as incandescent bulbs and LEDs, or linear light sources such as fluorescent lamps, making them highly useful as surface light sources for lighting applications.

[0005] Displays and lighting devices using such light-emitting devices are suitable for a variety of electronic devices, but research and development is ongoing to find light-emitting devices with even better characteristics.

[0006] One of the problems often cited when discussing organic EL devices is their low light extraction efficiency. To improve this, a structure has been proposed in which a layer made of a low refractive index material is formed inside the EL layer (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] US Patent Application Publication No. 2020 / 0176692 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of one embodiment of the present invention is to provide a light-emitting device with high emission efficiency, or to provide a light-emitting device, a light-emitting apparatus, an electronic device, a display device, or an electronic device with low power consumption.

[0009] The present invention is intended to solve any one of the above problems. [Means for solving the problem]

[0010] One aspect of the present invention is an electronic device comprising an anode, a cathode, and an EL layer located between the anode and the cathode, the EL layer comprising a first layer, a second layer, and a third layer, the first layer being located between the anode and the second layer, and the third layer being located between the second layer and the cathode, the first layer containing an organic compound having hole-transporting properties, the third layer containing an organic compound having electron-transporting properties, the organic compound having hole-transporting properties being a monoamine compound, the ratio of carbon atoms forming bonds via sp3 hybrid orbitals to the total number of carbon atoms in the monoamine compound being 23% to 55%, and the organic compound having hole-transporting properties and the organic compound having electron-transporting properties each having an ordinary refractive index of 1.5 to 1.75 for light with a wavelength of 455 nm to 465 nm.

[0011] Alternatively, another embodiment of the present invention provides an organic EL device including an anode, a cathode, and an EL layer located between the anode and the cathode, the EL layer including a first layer, a second layer, and a third layer, the first layer being located between the anode and the second layer, the third layer being located between the second layer and the cathode, the first layer including an organic compound having a hole-transporting property, the third layer including an organic compound having an electron-transporting property, the organic compound having an electron-transporting property including at least one nitrogen-containing six-membered heteroaromatic ring and a base, The electronic device has two benzene rings, one or more aromatic hydrocarbon rings having 6 to 14 carbon atoms, and a hydrocarbon group that forms bonds with multiple sp3 hybridized orbitals, wherein the total number of carbon atoms that form bonds with the sp3 hybridized orbitals is 10% to 60% of the total number of carbon atoms in the molecule of the organic compound having electron transport properties, and the organic compound having hole transport properties and the organic compound having electron transport properties each have an ordinary refractive index of 1.5 to 1.75 for light with a wavelength of 455 nm to 465 nm.

[0012] Alternatively, another embodiment of the present invention provides an organic EL device comprising an anode, a cathode, and an EL layer located between the anode and the cathode, the EL layer comprising a first layer, a second layer, and a third layer, the first layer being located between the anode and the second layer, the third layer being located between the second layer and the cathode, the first layer containing an organic compound having a hole transporting property, the third layer containing an organic compound having an electron transporting property, the organic compound having a hole transporting property being a monoamine compound, and a ratio of carbon atoms forming bonds via sp3 hybrid orbitals to the total number of carbon atoms in the monoamine compound being 23% or more and 55% or less, In the electronic device, the organic compound having electron transport properties has at least one nitrogen-containing six-membered heteroaromatic ring, two benzene rings, one or more aromatic hydrocarbon rings having 6 to 14 carbon atoms, and a hydrocarbon group that forms bonds with multiple sp3 hybridized orbitals, and the total number of carbon atoms that form bonds with the sp3 hybridized orbitals is 10% to 60% of the total number of carbon atoms in the molecule of the organic compound having electron transport properties, and the organic compound having hole transport properties and the organic compound having electron transport properties each have an ordinary refractive index of 1.5 to 1.75 for light with a wavelength of 455 nm to 465 nm.

[0013] Another embodiment of the present invention is an electronic device comprising an anode, a cathode, and an EL layer located between the anode and the cathode, the EL layer comprising a first layer, a second layer, and a third layer, the first layer being located between the anode and the second layer, and the third layer being located between the second layer and the cathode, the first layer containing an organic compound having hole-transporting properties, the third layer containing an organic compound having electron-transporting properties, the organic compound having hole-transporting properties being a monoamine compound, the ratio of carbon atoms forming bonds via sp3 hybrid orbitals to the total number of carbon atoms in the monoamine compound being 23% or more and 55% or less, and the organic compound having hole-transporting properties and the organic compound having electron-transporting properties each having an ordinary refractive index of 1.45 or more and 1.70 or less for light with a wavelength of 633 nm.

[0014] Alternatively, another embodiment of the present invention provides an organic light-emitting device comprising an anode, a cathode, and an EL layer located between the anode and the cathode, the EL layer including a first layer, a second layer, and a third layer, the first layer being located between the anode and the second layer, the third layer being located between the second layer and the cathode, the first layer including an organic compound having a hole-transporting property, the third layer including an organic compound having an electron-transporting property, and the organic compound having an electron-transporting property including at least one nitrogen-containing six-membered heteroaromatic ring. and an organic compound having electron transport properties, the organic compound having hole transport properties, and the organic compound having electron transport properties each have an ordinary refractive index of 1.45 to 1.70 for light having a wavelength of 633 nm.

[0015] Alternatively, another embodiment of the present invention provides an organic EL device comprising an anode, a cathode, and an EL layer located between the anode and the cathode, the EL layer comprising a first layer, a second layer, and a third layer, the first layer being located between the anode and the second layer, the third layer being located between the second layer and the cathode, the first layer containing an organic compound having a hole-transporting property, the third layer containing an organic compound having an electron-transporting property, the organic compound having a hole-transporting property being a monoamine compound, and a ratio of carbon atoms forming bonds via sp3 hybrid orbitals to the total number of carbon atoms in the monoamine compound being 23% or more and 55% or less. the organic compound having electron transport properties has at least one nitrogen-containing six-membered heteroaromatic ring, two benzene rings, one or more aromatic hydrocarbon rings having 6 to 14 carbon atoms, and a hydrocarbon group bonded via a plurality of sp3 hybridized orbitals, the total number of carbon atoms bonded via the sp3 hybridized orbitals being 10% or more and 60% or less of the total number of carbon atoms in the molecule of the organic compound having electron transport properties, and the organic compound having hole transport properties and the organic compound having electron transport properties each have an ordinary refractive index of 1.45 or more and 1.70 or less for light with a wavelength of 633 nm.

[0016] Alternatively, another embodiment of the present invention is an electronic device having the above structure, wherein the first layer is a hole transport layer and / or a hole injection layer.

[0017] Alternatively, another embodiment of the present invention is an electronic device having the above structure, wherein the third layer is an electron transport layer and / or an electron injection layer.

[0018] Alternatively, another aspect of the present invention is an electronic device having the above-described configuration, wherein one or both of the anode and the cathode have a function of reflecting all or part of light emitted from the electronic device or light incident on the electronic device.

[0019] Alternatively, another aspect of the present invention is an electronic device having the above-described structure, wherein one or both of the anode and the cathode contain a metal.

[0020] Another embodiment of the present invention is an electronic device having the above structure, wherein the second layer emits light.

[0021] One aspect of the present invention is a light-emitting device comprising an anode, a cathode, and an EL layer located between the anode and the cathode, the EL layer comprising a first layer, a second layer, and a third layer, the first layer being located between the anode and the second layer, and the third layer being located between the second layer and the cathode, the first layer containing an organic compound having hole-transporting properties, the third layer containing an organic compound having electron-transporting properties, the organic compound having hole-transporting properties being a monoamine compound, the ratio of carbon atoms forming bonds via sp3 hybrid orbitals to the total number of carbon atoms in the monoamine compound being 23% to 55%, and the organic compound having hole-transporting properties and the organic compound having electron-transporting properties each having an ordinary refractive index of 1.5 to 1.75 for light with a wavelength of 455 nm to 465 nm.

[0022] Alternatively, another embodiment of the present invention provides an organic EL device including an anode, a cathode, and an EL layer located between the anode and the cathode, the EL layer including a first layer, a second layer, and a third layer, the first layer being located between the anode and the second layer, the third layer being located between the second layer and the cathode, the first layer including an organic compound having a hole-transporting property, the third layer including an organic compound having an electron-transporting property, the organic compound having an electron-transporting property including at least one nitrogen-containing six-membered heteroaromatic ring and a base, The organic compound has two benzene rings, one or more aromatic hydrocarbon rings having 6 to 14 carbon atoms, and a hydrocarbon group that forms bonds with multiple sp3 hybridized orbitals, and the total number of carbon atoms that form bonds with the sp3 hybridized orbitals is 10% or more and 60% or less of the total number of carbon atoms in the molecule of the organic compound with electron transport properties, and the organic compound with hole transport properties and the organic compound with electron transport properties each have an ordinary refractive index of 1.5 or more and 1.75 or less for light with a wavelength of 455 nm or more and 465 nm or less.

[0023] Alternatively, another embodiment of the present invention provides an organic EL device comprising an anode, a cathode, and an EL layer located between the anode and the cathode, the EL layer comprising a first layer, a second layer, and a third layer, the first layer being located between the anode and the second layer, the third layer being located between the second layer and the cathode, the first layer containing an organic compound having a hole transporting property, the third layer containing an organic compound having an electron transporting property, the organic compound having a hole transporting property being a monoamine compound, and a ratio of carbon atoms forming bonds via sp3 hybrid orbitals to the total number of carbon atoms in the monoamine compound being 23% or more and 55% or less, In the light-emitting device, the organic compound having electron transport properties has at least one nitrogen-containing six-membered heteroaromatic ring, two benzene rings, one or more aromatic hydrocarbon rings having 6 to 14 carbon atoms, and a hydrocarbon group that forms bonds with multiple sp3 hybridized orbitals, and the total number of carbon atoms that form bonds with the sp3 hybridized orbitals is 10% or more and 60% or less of the total number of carbon atoms in the molecule of the organic compound having electron transport properties, and the organic compound having hole transport properties and the organic compound having electron transport properties each have an ordinary refractive index of 1.5 or more and 1.75 or less for light with a wavelength of 455 nm or more and 465 nm or less.

[0024] Another embodiment of the present invention is a light-emitting device comprising an anode, a cathode, and an EL layer located between the anode and the cathode, the EL layer comprising a first layer, a second layer, and a third layer, the first layer being located between the anode and the second layer, and the third layer being located between the second layer and the cathode, the first layer containing an organic compound having hole-transporting properties, the third layer containing an organic compound having electron-transporting properties, the organic compound having hole-transporting properties being a monoamine compound, the ratio of carbon atoms forming bonds via sp3 hybrid orbitals to the total number of carbon atoms in the monoamine compound being 23% or more and 55% or less, and the organic compound having hole-transporting properties and the organic compound having electron-transporting properties each having an ordinary refractive index of 1.45 or more and 1.70 or less for light with a wavelength of 633 nm.

[0025] Alternatively, another embodiment of the present invention provides an organic light-emitting device comprising an anode, a cathode, and an EL layer located between the anode and the cathode, the EL layer including a first layer, a second layer, and a third layer, the first layer being located between the anode and the second layer, the third layer being located between the second layer and the cathode, the first layer including an organic compound having a hole-transporting property, the third layer including an organic compound having an electron-transporting property, and the organic compound having an electron-transporting property including at least one nitrogen-containing six-membered heteroaromatic ring. and a light-emitting device having two benzene rings, one or more aromatic hydrocarbon rings having 6 to 14 carbon atoms, and a hydrocarbon group bonded with a plurality of sp3 hybridized orbitals, wherein the total number of carbon atoms bonded with the sp3 hybridized orbitals is 10% or more and 60% or less of the total number of carbon atoms in the molecule of the organic compound having electron transport properties, and wherein the organic compound having hole transport properties and the organic compound having electron transport properties each have an ordinary refractive index of 1.45 or more and 1.70 or less for light with a wavelength of 633 nm.

[0026] Alternatively, another embodiment of the present invention provides an organic EL device comprising an anode, a cathode, and an EL layer located between the anode and the cathode, the EL layer comprising a first layer, a second layer, and a third layer, the first layer being located between the anode and the second layer, the third layer being located between the second layer and the cathode, the first layer containing an organic compound having a hole-transporting property, the third layer containing an organic compound having an electron-transporting property, the organic compound having a hole-transporting property being a monoamine compound, and a ratio of carbon atoms forming bonds via sp3 hybrid orbitals to the total number of carbon atoms in the monoamine compound being 23% or more and 55% or less. the organic compound having electron transport properties has at least one nitrogen-containing six-membered heteroaromatic ring, two benzene rings, one or more aromatic hydrocarbon rings having 6 to 14 carbon atoms, and a hydrocarbon group bonded with a plurality of sp3 hybridized orbitals, the total number of carbon atoms bonded with the sp3 hybridized orbitals being 10% or more and 60% or less of the total number of carbon atoms in the molecule of the organic compound having electron transport properties, and the organic compound having hole transport properties and the organic compound having electron transport properties each have an ordinary refractive index of 1.45 or more and 1.70 or less for light with a wavelength of 633 nm.

[0027] Alternatively, another embodiment of the present invention is a light-emitting device having the above structure, wherein the first layer is a hole transport layer and / or a hole injection layer.

[0028] Alternatively, another embodiment of the present invention is a light-emitting device having the above structure, wherein the third layer is an electron transport layer and / or an electron injection layer.

[0029] Another aspect of the present invention is a light-emitting device having the above-described structure, wherein one or both of the anode and the cathode have a function of reflecting all or part of the light emitted from the light-emitting device.

[0030] Another aspect of the present invention is a light-emitting device having the above structure, wherein one or both of the anode and the cathode contain a metal.

[0031] Another embodiment of the present invention is a light-emitting device having the above structure, in which the second layer emits light.

[0032] Another embodiment of the present invention is an electronic device including the above electronic device or light-emitting device and at least one of a sensor, an operation button, a speaker, and a microphone.

[0033] Another embodiment of the present invention is a light-emitting device including the above electronic device or light-emitting device and at least one of a transistor and a substrate.

[0034] Another embodiment of the present invention is a lighting device including the electronic device or light-emitting device described above and a housing.

[0035] In this specification, the term "light-emitting device" includes an image display device using a light-emitting device. The term "light-emitting device" may also include a module in which a connector, such as an anisotropic conductive film or TCP (Tape Carrier Package), is attached to a light-emitting device, a module in which a printed wiring board is provided at the end of the TCP, or a module in which an IC (integrated circuit) is directly mounted on a light-emitting device using a COG (Chip On Glass) method. Furthermore, lighting fixtures and the like may include a light-emitting device. [Effects of the Invention]

[0036] According to one embodiment of the present invention, a light-emitting device with high emission efficiency or a light-emitting device, a light-emitting apparatus, an electronic device, a display device, or an electronic device with low power consumption can be provided.

[0037] Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. Note that effects other than these will become apparent from the description in the specification, drawings, claims, etc., and it is possible to extract other effects from the description in the specification, drawings, claims, etc. [Brief explanation of the drawings]

[0038] [Figure 1] 1A, 1B, 1C and 1D are schematic diagrams of light emitting devices. [Figure 2] 2A and 2B are diagrams showing an active matrix light emitting device. [Figure 3] 3A and 3B are diagrams showing an active matrix light emitting device. [Figure 4] FIG. 4 is a diagram showing an active matrix light emitting device. [Figure 5] 5A and 5B are diagrams showing a passive matrix light emitting device. [Figure 6] 6A and 6B are diagrams illustrating a lighting device. [Figure 7] 7A, 7B1, 7B2 and 7C are diagrams showing electronic devices. [Figure 8] 8A, 8B and 8C are diagrams showing electronic devices. [Figure 9] FIG. 9 is a diagram showing a lighting device. [Figure 10] FIG. 10 is a diagram showing a lighting device. [Figure 11] FIG. 11 is a diagram showing an in-vehicle display device and a lighting device. [Figure 12] 12A and 12B are diagrams illustrating electronic devices. [Figure 13] 13A, 13B and 13C are diagrams showing electronic devices. [Figure 14] FIG. 14 shows the luminance-current density characteristics of the light-emitting device 1 and the comparative light-emitting devices 1 to 3. In FIG. [Figure 15] FIG. 15 shows the luminance-voltage characteristics of the light-emitting device 1 and the comparative light-emitting devices 1 to 3. As shown in FIG. [Figure 16] FIG. 16 shows the current efficiency-luminance characteristics of the light-emitting device 1 and the comparative light-emitting devices 1 to 3. In FIG. [Figure 17]FIG. 17 shows the current density-voltage characteristics of the light-emitting device 1 and the comparative light-emitting devices 1 to 3. In FIG. [Figure 18] FIG. 18 shows the blue index (BI)-luminance characteristics of the light-emitting device 1 and the comparative light-emitting devices 1 to 3. In FIG. [Figure 19] FIG. 19 shows the emission spectra of the light-emitting device 1 and the comparative light-emitting devices 1 to 3. As shown in FIG. [Figure 20] FIG. 20 shows data obtained by measuring the refractive index of mmtBumTPoFBi-02 and PCBBiF. [Figure 21] FIG. 21 shows data obtained by measuring the refractive indexes of mmtBumBPTzn, mPn-mDMePyPTzn, Li-6mq, and Liq. [Figure 22] FIG. 22 shows the data obtained by measuring the refractive index of mmtBumTPoFBi-02. [Figure 23] FIG. 23 shows data obtained by measuring the refractive index of mmtBumBPTzn. [Figure 24] FIG. 24 shows data obtained by measuring the refractive index of Li-6mq. [Figure 25] FIG. 25 is a graph showing the luminance-current density characteristics of comparative light-emitting device 10, comparative light-emitting device 11, comparative light-emitting device 12, and light-emitting device 10. In FIG. [Figure 26] FIG. 26 is a graph showing the current efficiency-luminance characteristics of comparative light-emitting device 10, comparative light-emitting device 11, comparative light-emitting device 12, and light-emitting device 10. In FIG. [Figure 27] FIG. 27 is a graph showing the luminance-voltage characteristics of comparative light-emitting device 10, comparative light-emitting device 11, comparative light-emitting device 12, and light-emitting device 10. In FIG. [Figure 28] FIG. 28 is a graph showing the current-voltage characteristics of comparative light-emitting device 10, comparative light-emitting device 11, comparative light-emitting device 12, and light-emitting device 10. In FIG. [Figure 29] FIG. 29 is a graph showing the blue index-luminance characteristics of the comparative light-emitting device 10, the comparative light-emitting device 11, the comparative light-emitting device 12, and the light-emitting device 10. In FIG. [Figure 30] FIG. 30 is a graph showing the emission spectra of comparative light-emitting device 10, comparative light-emitting device 11, comparative light-emitting device 12, and light-emitting device 10. [Figure 31] FIG. 31 shows data obtained by measuring the refractive index of dchPAF and PCBBiF. DETAILED DESCRIPTION OF THE INVENTION

[0039] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it will be readily understood by those skilled in the art that various changes in form and details can be made without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the description of the embodiments shown below.

[0040] (Embodiment 1)

[0041] FIG. 1A shows a light-emitting device according to one embodiment of the present invention. FIG. 1 shows a structure including an anode 101, a cathode 102, and an EL layer 103. The EL layer 103 includes a hole-injection layer 111, a hole-transport layer 112, a light-emitting layer 113, an electron-transport layer 114, and an electron-injection layer 115. The light-emitting layer 113 is a layer containing at least a light-emitting material. The configuration of the EL layer 103 is not limited to this, and it may be configured such that some of the above layers are not formed, or that other functional layers such as a carrier block layer, an exciton block layer, or an intermediate layer are formed.

[0042] In one embodiment of the present invention, a low refractive index layer is provided in both the region between the light-emitting layer 113 and the anode 101 in the EL layer 103 (hole transport region 120) and the region between the light-emitting layer 113 and the cathode 102 (electron transport region 121).

[0043] The low refractive index layer is a layer-like region substantially parallel to the anode 101 and the cathode 102, and is a region exhibiting a refractive index lower than at least the light-emitting layer 113. Since the refractive index of organic compounds constituting a light-emitting device is usually about 1.8 to 1.9, the refractive index of the low refractive index layer is preferably 1.75 or less, more specifically, the ordinary refractive index in the blue light-emitting region (455 nm or more and 465 nm or less) is preferably 1.50 or more and 1.75 or less, or the ordinary refractive index for 633 nm light, which is usually used for measuring refractive index, is preferably 1.45 or more and 1.70 or less.

[0044] When light is incident on a material with optical anisotropy, the light in the vibration plane parallel to the optical axis is called extraordinary light (ray), and the light in the vibration plane perpendicular to the optical axis is called ordinary light (ray). However, the refractive index of the material for ordinary light and extraordinary light may differ. In such cases, anisotropy analysis can be performed to separate the ordinary and extraordinary refractive indices and calculate each refractive index. In this specification, if the measured material has both an ordinary refractive index and an extraordinary refractive index, the ordinary refractive index will be used as the index.

[0045] Furthermore, the hole transport region 120 and the electron transport region 121 do not all need to be low refractive index layers, but rather it is sufficient that at least a portion of each in the thickness direction of the hole transport region 120 and the electron transport region 121 is provided as a low refractive index layer. For example, in the hole transport region 120, at least one of the functional layers provided in the hole transport region 120, such as the hole injection layer 111, the hole transport layer 112, and the electron blocking layer, is a low refractive index layer, and in the electron transport region 121, at least one of the functional layers provided in the electron transport region 121, such as the hole blocking layer, the electron transport layer 114, and the electron injection layer 115, is a low refractive index layer.

[0046] A low-refractive index layer can be formed by forming each functional layer using a material with a relatively low refractive index. However, there is usually a trade-off between high carrier transport and a low refractive index. This is because the carrier transport properties of organic compounds are largely due to the presence of unsaturated bonds, and organic compounds with many unsaturated bonds tend to have a high refractive index. Even if a material has a low refractive index, if its carrier transport properties are poor, problems such as increased driving voltage and reduced luminous efficiency and reliability due to carrier imbalance can occur, making it difficult to obtain a light-emitting device with good characteristics. Furthermore, even if a material has sufficient carrier transport properties and a low refractive index, if it has an unstable structure and has problems with the glass transition temperature (Tg) or durability, it will be difficult to obtain a reliable light-emitting device.

[0047] Therefore, as an organic compound having hole transport properties that can be used in the hole transport region 120, it is preferable to use a monoamine compound that has a first aromatic group, a second aromatic group, and a third aromatic group, and the first aromatic group, the second aromatic group, and the third aromatic group are bonded to the same nitrogen atom.

[0048] In the monoamine compound, the ratio of carbon atoms forming bonds with sp3 hybrid orbitals to the total number of carbon atoms in the molecule is preferably 23% or more and 55% or less, and 1 The monoamine compound is preferably a compound in which the integral value of a signal below 4 ppm exceeds the integral value of a signal at 4 ppm or more when the compound is measured by H-NMR.

[0049] Furthermore, it is preferable that the monoamine compound has at least one fluorene skeleton, and any one or more of the first aromatic group, the second aromatic group, and the third aromatic group has a fluorene skeleton.

[0050] Examples of the organic compound having the hole transporting property as described above include those having the following general formula (G h1 1)~(G h14) An example of an organic compound having the structure shown below is:

[0051] [ka]

[0052] The above general formula (G h1 In 1), Ar 1 , Ar 2 each independently represents a benzene ring or a substituent in which two or three benzene rings are bonded to each other. 1 , Ar 2 one or both of the groups have one or more hydrocarbon groups having 1 to 12 carbon atoms, in which carbon atoms form bonds only through sp3 hybrid orbitals, and Ar 1 and Ar 2 The total number of carbon atoms contained in all the hydrocarbon groups bonded to Ar is 8 or more, and 1 and Ar 2 The total number of carbon atoms contained in all the hydrocarbon groups bonded to either one of Ar 1 or Ar 2 When a plurality of linear alkyl groups having 1 or 2 carbon atoms are bonded to the hydrocarbon group, the linear alkyl groups may be bonded to each other to form a ring.

[0053] [ka]

[0054] The above general formula (G h1 In 2), m and r each independently represent 1 or 2, and m+r is 2 or 3. Each t independently represents an integer of 0 to 4, preferably 0. 5represents either hydrogen or a hydrocarbon group having 1 to 3 carbon atoms. When m is 2, the types of substituents, the number of substituents, and the positions of bonds of the two phenylene groups may be the same or different, and when r is 2, the types of substituents, the number of substituents, and the positions of bonds of the two phenyl groups may be the same or different. When t is an integer of 2 to 4, a plurality of R 5 may be the same or different, and R 5 Adjacent groups may be bonded to each other to form a ring.

[0055] [ka]

[0056] The above general formula (G h1 2) and (G h1 In 3), n and p each independently represent 1 or 2, and n+p is 2 or 3. Each s independently represents an integer of 0 to 4, preferably 0. 4 represents either hydrogen or a hydrocarbon group having 1 to 3 carbon atoms, and when n is 2, the types of substituents, the number of substituents, and the positions of bonds of the two phenylene groups may be the same or different, and when p is 2, the types of substituents, the number of substituents, and the positions of bonds of the two phenyl groups may be the same or different. 4 may be the same or different.

[0057] [ka]

[0058] The above general formula (G h1 2)~(G h1 4) In R 10 ~R 14 and R 20 ~R 24Each independently represents hydrogen or a hydrocarbon group having 1 to 12 carbon atoms in which carbon atoms form bonds only through sp3 hybrid orbitals. 10 ~R 14 At least 3 of, and R 20 ~R 24 Preferably, at least 3 of the R groups are hydrogen atoms. As hydrocarbon groups having 1 to 12 carbon atoms in which carbon atoms form bonds only through sp3 hybrid orbitals, tert-butyl and cyclohexyl groups are preferred. 10 ~R 14 and R 20 ~R 24 The total number of carbon atoms contained in is 8 or more, and R 10 ~R 14 or R 20 ~R 24 The total number of carbon atoms in either of the two groups must be 6 or more. 4 , R 10 ~R 14 and R 20 ~R 24 Adjacent groups may be bonded to each other to form a ring.

[0059] In addition, the above general formula (G h1 1)~(G h1 In 4), u represents an integer of 0 to 4, and is preferably 0. When u is an integer of 2 to 4, a plurality of R 3 may be the same or different. 1 , R 2 and R 3 each independently represents an alkyl group having 1 to 4 carbon atoms; R 1 and R 2 may be bonded to each other to form a ring.

[0060] Another preferred material having hole transport properties that can be used in the hole transport region 120 is an arylamine compound having at least one aromatic group, the aromatic group having first to third benzene rings and at least three alkyl groups. The first to third benzene rings are bonded in this order, and the first benzene ring is directly bonded to the nitrogen of the amine.

[0061] The first benzene ring may further have a substituted or unsubstituted phenyl group, preferably an unsubstituted phenyl group, and the second benzene ring or the third benzene ring may have a phenyl group substituted with an alkyl group.

[0062] It should be noted that hydrogen is not directly bonded to the carbon atoms at the first and third positions of two or more of the first to third benzene rings, preferably all of the benzene rings, but is bonded to any of the first to third benzene rings, the phenyl group substituted with an alkyl group, the at least three alkyl groups, and the nitrogen of the amine.

[0063] The arylamine compound preferably further has a second aromatic group. The second aromatic group is preferably an unsubstituted monocyclic ring or a group having substituted or unsubstituted fused rings of three or less, more preferably a substituted or unsubstituted fused ring of three or less, and the fused ring is more preferably a group having a fused ring with 6 to 13 carbon atoms forming the ring, and even more preferably a group having a fluorene ring. The second aromatic group is preferably a dimethylfluorenyl group.

[0064] The arylamine compound preferably further comprises a third aromatic group, which is a group having one to three substituted or unsubstituted benzene rings.

[0065] The at least three alkyl groups and the alkyl group substituting the phenyl group are preferably chain alkyl groups having 2 to 5 carbon atoms. In particular, the alkyl group is preferably a branched chain alkyl group having 3 to 5 carbon atoms, and more preferably a t-butyl group.

[0066] Examples of the material having the hole transporting property as described above include the following (G h2 1)~(G h23) An example of an organic compound having the structure shown below is an organic compound having the structure shown below.

[0067] [ka]

[0068] In addition, the above general formula (G h2 In 1), Ar 101 represents a substituted or unsubstituted benzene ring, or a substituent in which two or three substituted or unsubstituted benzene rings are bonded to each other.

[0069] [ka]

[0070] In addition, the above general formula (G h2 In 2), x and y each independently represent 1 or 2, and x+y is 2 or 3. 109 represents an alkyl group having 1 to 4 carbon atoms, and w represents an integer of 0 to 4. 141 ~R 145 Each independently represents one of hydrogen, an alkyl group having 1 to 6 carbon atoms, and a cycloalkyl group having 5 to 12 carbon atoms. When w is 2 or more, multiple R 109 may be the same or different. When x is 2, the type of substituents, the number of substituents, and the position of the bond of the two phenylene groups may be the same or different. When y is 2, the two R 141 ~R 145 The types and numbers of the substituents on the phenyl groups having the formula (I) may be the same or different.

[0071] [ka]

[0072] In addition, the above general formula (G h2 3) In R 101 ~R 105each independently represents one of hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 6 to 12 carbon atoms, and a substituted or unsubstituted phenyl group.

[0073] In addition, the above general formula (G h2 1)~(G h2 3) and R 106 , R 107 and R 108 Each independently represents an alkyl group having 1 to 4 carbon atoms, and v represents an integer of 0 to 4. When v is 2 or more, a plurality of R 108 may be the same or different. 111 ~R 115 One of R is a substituent represented by the above general formula (g1), and the rest each independently represent one of hydrogen, an alkyl group having 1 to 6 carbon atoms, and a substituted or unsubstituted phenyl group. 121 ~R 125 One of R is a substituent represented by the above general formula (g2), and the remaining R each independently represent one of hydrogen, an alkyl group having 1 to 6 carbon atoms, and a phenyl group substituted with an alkyl group having 1 to 6 carbon atoms. 131 ~R 135 Each of R independently represents one of hydrogen, an alkyl group having 1 to 6 carbon atoms, and a phenyl group substituted with an alkyl group having 1 to 6 carbon atoms. 111 ~R 115 , R 121 ~R 125 and R 131 ~R 135 At least three of the R 111 ~R 115 The number of substituted or unsubstituted phenyl groups in R is 1 or less, 121 ~R 125 and R 131 ~R 135 In R, the number of phenyl groups substituted with alkyl groups having 1 to 6 carbon atoms is 1 or less. 112 and R 114 , R122 and R 124 , and R 132 and R 134 In at least two of the three combinations, at least one R is other than hydrogen.

[0074] The organic compound having hole transport properties as described above has an ordinary refractive index of 1.50 to 1.75 in the blue light emission region (455 nm to 465 nm) or an ordinary refractive index of 1.45 to 1.70 in the 633 nm light typically used for measuring refractive index, and is an organic compound with good hole transport properties. It is also possible to obtain an organic compound with high Tg and good reliability. Such organic compounds having hole transport properties can be used as materials for the hole transport layer 112 because they have sufficient hole transport properties.

[0075] Note that when the organic compound having a hole-transporting property is used for the hole-injection layer 111, it is preferable to mix a substance having an acceptor property with the organic compound having a hole-transporting property. As the acceptor substance, a compound having an electron-withdrawing group (a halogen group or a cyano group) can be used, and examples thereof include 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-TCNNQ), and 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyren-2-ylidene)malononitrile. In particular, compounds in which an electron-withdrawing group is bonded to a fused aromatic ring having multiple heteroatoms, such as HAT-CN, are thermally stable and preferred. Radialene derivatives having electron-withdrawing groups (especially halogen groups such as fluoro groups or cyano groups) are also preferred because of their extremely high electron-accepting properties. Specific examples include α,α',α''-1,2,3-cyclopropanetriylidene tris[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α',α''-1,2,3-cyclopropanetriylidene tris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], and α,α',α''-1,2,3-cyclopropanetriylidene tris[2,3,4,5,6-pentafluorobenzeneacetonitrile].

[0076] In addition to the organic compounds described above, other materials with acceptor properties can include molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, and manganese oxide. The hole injection layer 111 can also be formed using phthalocyanine complex compounds such as phthalocyanine (abbreviated as HPc) and copper phthalocyanine (CuPc), aromatic amine compounds such as 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviated as DPAB) and N,N'-bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviated as DNTPD), or polymers such as poly(3,4-ethylenedioxythiophene) / poly(styrenesulfonic acid) (PEDOT / PSS). Acceptor materials can extract electrons from the adjacent hole transport layer (or hole transport material) when an electric field is applied.

[0077] When the hole injection layer 111 is formed by mixing the material having hole transport properties with the material having acceptor properties, the material for forming the electrode can be selected regardless of the work function. That is, not only a material having a large work function but also a material having a small work function can be used for the anode 101.

[0078] As an organic compound having electron transport properties that can be used in the electron transport region 121, it is preferable to use an organic compound that has at least one six-membered heteroaromatic ring containing one to three nitrogen atoms, has multiple aromatic hydrocarbon rings that form the ring and have 6 to 14 carbon atoms, at least two of the multiple aromatic hydrocarbon rings are benzene rings, and has multiple hydrocarbon groups that form bonds with sp3 hybrid orbitals.

[0079] In addition, in such an organic compound, the ratio of the total number of carbon atoms forming bonds with sp3 hybrid orbitals to the total number of carbon atoms in the molecule of the organic compound is preferably 10% or more and 60% or less, more preferably 10% or more and 50% or less. 1In the results of measuring the organic compound by H-NMR, the integral value of signals below 4 ppm is preferably at least half the integral value of signals at 4 ppm or higher.

[0080] The molecular weight of the organic compound having electron transport properties is preferably from 500 to 2000. Furthermore, it is preferable that all of the hydrocarbon groups forming bonds with sp3 hybrid orbitals possessed by the organic compound are bonded to the aromatic hydrocarbon ring having 6 to 14 carbon atoms that forms the ring, and that the LUMO of the organic compound is not distributed in the aromatic hydrocarbon ring.

[0081] The organic compound having the electron transport property is a compound represented by the following general formula (G e1 1) or (G e1 The organic compound represented by 2) is preferred.

[0082] [ka]

[0083] In the formula, A represents a 6-membered heteroaromatic ring containing 1 to 3 nitrogen atoms, and is preferably a pyridine ring, a pyrimidine ring, a pyrazine ring, a pyridazine ring, or a triazine ring.

[0084] Also, R 200 is hydrogen, an alkyl group having 1 to 6 carbon atoms, an alicyclic group having 3 to 10 carbon atoms, or a group represented by the formula (G1 e1 -1).

[0085] R 201 ~R 215 At least one of R is a phenyl group having a substituent, and the others each independently represent any one of hydrogen, an alkyl group having 1 to 6 carbon atoms, an alicyclic group having 3 to 10 carbon atoms, a substituted or unsubstituted ring-forming aromatic hydrocarbon group having 6 to 14 carbon atoms, and a substituted or unsubstituted pyridyl group. 201 , R 203 , R 205 , R 206 , R 208 , R210 , R 211 , R 213 and R 215 is preferably hydrogen. The phenyl group having the substituent has one or two substituents, each of which is independently any one of an alkyl group having 1 to 6 carbon atoms, an alicyclic group having 3 to 10 carbon atoms, and a substituted or unsubstituted aromatic hydrocarbon group having 6 to 14 carbon atoms in a ring.

[0086] In addition, the above general formula (G e1 The organic compound represented by 1) has a plurality of hydrocarbon groups selected from alkyl groups having 1 to 6 carbon atoms and alicyclic groups having 3 to 10 carbon atoms, and the ratio of the total number of carbon atoms forming bonds with sp3 hybrid orbitals to the total number of carbon atoms in the molecule is 10% or more and 60% or less.

[0087] In addition, the organic compound having the electron transport property is a compound represented by the following general formula (G e1 The organic compound represented by 2) is preferred.

[0088] [ka]

[0089] In the formula, Q 1 ~Q 3 2 or 3 of the groups represent N, and the Q 1 ~Q 3 If two of the groups are N, the remaining group represents CH.

[0090] Also R 201 ~R 215 At least one of R is a phenyl group having a substituent, and the others each independently represent any one of hydrogen, an alkyl group having 1 to 6 carbon atoms, an alicyclic group having 3 to 10 carbon atoms, a substituted or unsubstituted ring-forming aromatic hydrocarbon group having 6 to 14 carbon atoms, and a substituted or unsubstituted pyridyl group. 201 , R 203 , R 205 , R 206 , R 208 , R 210 , R 211, R 213 and R 215 is preferably hydrogen. The phenyl group having a substituent has one or two substituents, each of which is independently any one of an alkyl group having 1 to 6 carbon atoms, an alicyclic group having 3 to 10 carbon atoms, and a substituted or unsubstituted aromatic hydrocarbon group having 6 to 14 carbon atoms in a ring.

[0091] In addition, the above general formula (G e1 The organic compound represented by 2) preferably has a plurality of hydrocarbon groups selected from alkyl groups having 1 to 6 carbon atoms and alicyclic groups having 3 to 10 carbon atoms, and the ratio of the total number of carbon atoms forming bonds via sp3 hybrid orbitals to the total number of carbon atoms in the molecule is 10% or more and 60% or less.

[0092] In addition, the above general formula (G e1 1) or (G e1 In the organic compound represented by formula (G e1 1-2) is preferred.

[0093] [ka]

[0094] In the formula, α represents a substituted or unsubstituted phenylene group, and is preferably a meta-substituted phenylene group. Furthermore, when the meta-substituted phenylene group has one substituent, the substituent is preferably also substituted at the meta-position. The substituent is preferably an alkyl group having 1 to 6 carbon atoms or an alicyclic group having 3 to 10 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms, and even more preferably a t-butyl group.

[0095] R 220 represents an alkyl group having 1 to 6 carbon atoms, an alicyclic group having 3 to 10 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 14 carbon atoms in a ring.

[0096] Furthermore, j and k represent 1 or 2. When j is 2, the multiple α may be the same or different. When k is 2, the multiple R 220 may be the same or different. 220 is preferably a phenyl group, and is a phenyl group having an alkyl group having 1 to 6 carbon atoms or an alicyclic group having 3 to 10 carbon atoms at one or both of the two meta positions. The substituents that the phenyl group has at one or both of the two meta positions are more preferably alkyl groups having 1 to 6 carbon atoms, and even more preferably t-butyl groups.

[0097] The organic compound having the electron transport property as described above is an organic compound having an ordinary refractive index of 1.50 or more and 1.75 or less in the blue light emission region (455 nm or more and 465 nm or less), or an ordinary refractive index of 1.45 or more and 1.70 or less for light of 633 nm, which is usually used for measuring refractive index, and having good electron transport property.

[0098] When the electron-transporting organic compound is used in the electron-transporting layer 114, the electron-transporting layer 114 preferably further contains a metal complex of an alkali metal or an alkaline earth metal. Heterocyclic compounds having a diazine skeleton, heterocyclic compounds having a triazine skeleton, and heterocyclic compounds having a pyridine skeleton are preferred from the viewpoint of operating life because they easily stabilize the energy when they form an exciplex with an organometallic complex of an alkali metal (easily lengthening the emission wavelength of the exciplex). In particular, heterocyclic compounds having a diazine skeleton and heterocyclic compounds having a triazine skeleton are suitable for stabilizing the energy of the exciplex because they have a deep LUMO level.

[0099] The alkali metal organometallic complex is preferably a lithium organometallic complex. Alternatively, the alkali metal organometallic complex preferably has a ligand having a quinolinol skeleton. More preferably, the alkali metal organometallic complex is a lithium complex containing an 8-quinolinolato structure or a derivative thereof. As a derivative of a lithium complex containing an 8-quinolinolato structure, a lithium complex containing an 8-quinolinolato structure having an alkyl group is preferred, and a methyl group is particularly preferred.

[0100] When the lithium complex containing the 8-quinolinolato structure has an alkyl group, it is preferable that the complex has only one alkyl group. 8-quinolinolato-lithium having an alkyl group can be a metal complex with a low refractive index. Specifically, in a thin film state, the ordinary refractive index for light with a wavelength in the range of 455 nm to 465 nm can be 1.45 to 1.70, and the ordinary refractive index for light with a wavelength of 633 nm can be 1.40 to 1.65.

[0101] In particular, the use of 6-alkyl-8-quinolinolato-lithium having an alkyl group at position 6 has the effect of reducing the driving voltage of a light-emitting device. Among 6-alkyl-8-quinolinolato-lithiums, it is more preferable to use 6-methyl-8-quinolinolato-lithium.

[0102] Here, the 6-alkyl-8-quinolinolatolithium can be represented by the following general formula (G1).

[0103] [ka]

[0104] In the above general formula (G1), R represents an alkyl group having 1 to 3 carbon atoms.

[0105] A more preferred embodiment of the metal complex represented by the general formula (G1) is a metal complex represented by the following structural formula (100).

[0106] [ka]

[0107] As described above, the organic compound having electron-transport properties used in the electron-transport layer 114 of the light-emitting device according to one embodiment of the present invention preferably has an alkyl group having 3 or 4 carbon atoms. In particular, the organic compound having electron-transport properties preferably has a plurality of such alkyl groups. However, since too many alkyl groups in a molecule reduces the carrier transport property, the proportion of carbon atoms forming bonds with sp3 hybrid orbitals in the organic compound having electron-transport properties is preferably 10% to 60%, more preferably 10% to 50%, of the total number of carbon atoms in the organic compound. An organic compound having electron-transport properties with such a structure can achieve a low refractive index without significantly impairing the electron-transport property.

[0108] As described above, by using an organic compound having a low refractive index and electron-transporting properties and a metal complex of an alkali metal having a low refractive index, a layer with a lower refractive index can be formed without significantly deteriorating the driving voltage, etc. As a result, the efficiency of extracting light from the light-emitting layer 113 is improved, and the light-emitting device of one embodiment of the present invention can be a light-emitting element with high emission efficiency.

[0109] Next, other examples of the structure and materials of the light-emitting device of one embodiment of the present invention will be described. As described above, the light-emitting device of one embodiment of the present invention includes an EL layer 103 composed of multiple layers between a pair of electrodes, an anode 101 and a cathode 102. The EL layer 103 includes a light-emitting layer 113 containing a light-emitting material, a hole-transporting region 120, and an electron-transporting region 121. The hole-transporting region 120 and the electron-transporting region 121 each include a low-refractive-index layer.

[0110] The anode 101 is preferably formed using a metal, alloy, conductive compound, or mixture thereof having a large work function (specifically, 4.0 eV or higher). Specific examples include indium tin oxide (ITO), indium tin oxide containing silicon or silicon oxide, indium zinc oxide, and indium oxide containing tungsten oxide and zinc oxide (IWZO). These conductive metal oxide films are typically formed by sputtering, but they may also be formed by applying a sol-gel method. For example, indium zinc oxide may be formed by sputtering using a target containing indium oxide and 1 to 20 wt% zinc oxide. Indium oxide containing tungsten oxide and zinc oxide (IWZO) may also be formed by sputtering using a target containing indium oxide and 0.5 to 5 wt% tungsten oxide and 0.1 to 1 wt% zinc oxide. Other examples of materials that can be used for the anode 101 include gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), and nitrides of metal materials (e.g., titanium nitride). Graphene can also be used as the material for the anode 101. By using a composite material (described later) in the layer of the EL layer 103 that is in contact with the anode 101, it becomes possible to select an electrode material regardless of the work function.

[0111] When the anode 101 is made of a material that is transparent to visible light, a light-emitting device that emits light from the cathode side can be formed, as shown in Fig. 1C. When the anode 101 is formed on the substrate side, this light-emitting device can be a so-called bottom-emission type light-emitting device.

[0112] The EL layer 103 preferably has a laminated structure, but the laminated structure is not particularly limited. Various functional layers can be used, such as a hole injection layer, a hole transport layer, an emitting layer, an electron transport layer, an electron injection layer, a carrier blocking layer (hole blocking layer, electron blocking layer), an exciton blocking layer, an intermediate layer, and a charge generation layer. Note that some layers may not be provided. In this embodiment, two types of structures are described: a structure having a hole injection layer 111, a hole transport layer 112, an electron transport layer 114, and an electron injection layer 115 in addition to the emitting layer 113, as shown in FIG. 1A; and a structure having a charge generation layer 116 in addition to the electron transport layer 114, the emitting layer 113, the hole injection layer 111, and the hole transport layer 112, as shown in FIG. 1B. At least one of the functional layers present in the hole transport region 120 and the electron transport region 121 is a low refractive index layer, and the structure has already been described. Below, specific materials that can be used to form these functional layers when they are not low refractive index layers are described.

[0113] The hole-injection layer 111 is a layer containing a substance having acceptor properties. As the substance having acceptor properties, either an organic compound or an inorganic compound can be used.

[0114] As the acceptor substance, a compound having an electron-withdrawing group (a halogen group or a cyano group) can be used, and examples thereof include 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-TCNNQ), and 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyren-2-ylidene)malononitrile. In particular, compounds in which an electron-withdrawing group is bonded to a fused aromatic ring having multiple heteroatoms, such as HAT-CN, are thermally stable and preferred. Radialene derivatives having electron-withdrawing groups (especially halogen groups such as fluoro groups or cyano groups) are also preferred because of their extremely high electron-accepting properties. Specific examples include α,α',α''-1,2,3-cyclopropanetriylidene tris[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α',α''-1,2,3-cyclopropanetriylidene tris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], and α,α',α''-1,2,3-cyclopropanetriylidene tris[2,3,4,5,6-pentafluorobenzeneacetonitrile]. In addition to the organic compounds described above, other materials having acceptor properties can include molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, manganese oxide, etc. The hole injection layer 111 can also be formed from phthalocyanine complex compounds such as phthalocyanine (abbreviated as HPc) and copper phthalocyanine (CuPc), aromatic amine compounds such as 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviated as DPAB) and N,N'-bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviated as DNTPD), or polymers such as poly(3,4-ethylenedioxythiophene) / poly(styrenesulfonic acid) (PEDOT / PSS).A substance having acceptor properties can extract electrons from an adjacent hole transport layer (or hole transport material) when an electric field is applied.

[0115] Furthermore, a composite material in which a material having a hole-transporting property contains the above-mentioned acceptor substance can also be used for the hole-injection layer 111. Note that by using a composite material in which a material having a hole-transporting property contains an acceptor substance, a material for forming an electrode can be selected regardless of the work function. In other words, not only a material with a high work function but also a material with a low work function can be used for the anode 101.

[0116] As a material having hole transport properties to be used in the composite material, various organic compounds such as aromatic amine compounds, carbazole derivatives, aromatic hydrocarbons, and polymer compounds (oligomers, dendrimers, polymers, etc.) can be used. Note that as a material having hole transport properties to be used in the composite material, -6 cm 2 A substance having a hole mobility of 1 / Vs or more is preferred. Specific examples of organic compounds that can be used as a material having a hole transport property in a composite material are listed below.

[0117] Examples of aromatic amine compounds that can be used in composite materials include N,N'-di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), N,N'-bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviation: DNTPD), and 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B). Specific examples of the carbazole derivative include 3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2), 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole, and Examples of suitable carbazoles include PCzPCN1, 4,4'-di(N-carbazolyl)biphenyl (CBP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (TCPB), 9-[4-(10-phenylanthracen-9-yl)phenyl]-9H-carbazole (CzPA), and 1,4-bis[4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene.Examples of aromatic hydrocarbons include 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 2-tert-butyl-9,10-di(1-naphthyl)anthracene, 9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA), 2-tert-butyl-9,10-bis(4-phenylphenyl)anthracene (abbreviation: t-BuDBA), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA), 9,10-diphenylanthracene (abbreviation: DPAnth), 2-tert-butylanthracene (abbreviation: t-BuAnth), 9,10-bis(4-methyl-1-naphthyl)anthracene (abbreviation: DMNA), 2-tert- Examples of suitable anthracene include butyl-9,10-bis[2-(1-naphthyl)phenyl]anthracene, 9,10-bis[2-(1-naphthyl)phenyl]anthracene, 2,3,6,7-tetramethyl-9,10-di(1-naphthyl)anthracene, 2,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene, 9,9'-bianthryl, 10,10'-diphenyl-9,9'-bianthryl, 10,10'-bis(2-phenylphenyl)-9,9'-bianthryl, 10,10'-bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9'-bianthryl, anthracene, tetracene, rubrene, perylene, and 2,5,8,11-tetra(tert-butyl)perylene. Pentacene and coronene may also be used. The aromatic hydrocarbon having a vinyl group may also have a vinyl skeleton. Examples of the aromatic hydrocarbon having a vinyl group include 4,4'-bis(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi) and 9,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene (abbreviation: DPVPA). Note that the organic compound of one embodiment of the present invention can also be used.

[0118] In addition, polymer compounds such as poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphenylamine) (abbreviation: PVTPA), poly[N-(4-{N'-[4-(4-diphenylamino)phenyl]phenyl-N'-phenylamino}phenyl)methacrylamide] (abbreviation: PTPDMA), and poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine] (abbreviation: Poly-TPD) can also be used.

[0119] The hole-transporting material used in the composite material preferably has a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, or an anthracene skeleton. In particular, the second organic compound may be an aromatic amine having a substituent containing a dibenzofuran ring or a dibenzothiophene ring, an aromatic monoamine having a naphthalene ring, or an aromatic monoamine in which a 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group. It is preferable that the second organic compound has an N,N-bis(4-biphenyl)amino group, since this allows the fabrication of a light-emitting device with a long lifetime. Specific examples of the second organic compound include N-(4-biphenyl)-6,N-diphenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BnfABP), N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf), 4,4'-bis(6-phenylbenzo[b]naphtho[1,2-d]furan- 8-yl-4''-phenyltriphenylamine (abbreviation: BnfBB1BP), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-6-amine (abbreviation: BBABnf(6)), N,N-bis(4-biphenyl)benzo[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''-diphenyltriphenylamine (abbreviation: : BBAβNB), 4-[4-(2-naphthyl)phenyl]-4',4''-diphenyltriphenylamine (abbreviation: BBAβNBi), 4,4'-diphenyl-4''-(6;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβNB), 4,4'-diphenyl-4''-(7;1'-binaphthyl-2-yl)triphenylamine (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-2-yl)triphenylamine (abbreviation: BBA(βN2)B-03), 4,4'-diphenyl-4''-(4;2'-binaphthyl-1-yl)triphenylamine (abbreviation: BBAβNαNB), 4,4'-diphenyl-4''-(5;2'- (binaphthyl-1-yl)triphenylamine (abbreviation: BBAβNαNB-02), 4-(4-biphenylyl)-4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: TPBiAβNB), 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 4,4'-Bis(1-naphthyl)triphenylamine (abbreviated as αNBA1BP), 4,4'-Bis(1-naphthyl)triphenylamine (abbreviated as αNBB1BP), 4,4'-diphenyl-4''-[4'-(carbazol-9-yl)biphenyl-4-yl]triphenylamine (abbreviated as YGTBi1BP), 4'-[4-(3-phenyl-9H-carbazol-9-yl)phenyl]tris(1,1'-biphenyl-4-yl)amine (abbreviated as YGTBi1BP-02), 4-diphenyl-4'-(2-naphthyl)-4''-{9-(4-biphenylyl)carbazole}triphenylamine N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-[4-(1-naphthyl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBNBSF), N,N-bis(4-biphenylyl)-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: BBASF), N,N-bis(1,1'-biphenyl-4-yl)-9,9'-spirobi[9H-fluorene]-4-amine (abbreviation: BBASF(4)), N-(1,1'-biphenyl-2-yl)-N-(9,9-Dimethyl-9H-fluoren-2-yl)-9,9'-spirobi(9H-fluorene)-4-amine (abbreviation: oFBiSF), N-(4-biphenyl)-N-(dibenzofuran-4-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: FrBiF), N-[4-(1-naphthyl)phenyl]-N-[3-(6-phenyldibenzofuran-4-yl)phenyl]-1-naphthylamine (abbreviation: mPDBfBNBN), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-furan phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviated as mBPAFLP), 4-phenyl-4'-[4-(9-phenylfluoren-9-yl)phenyl]triphenylamine (abbreviated as BPAFLBi), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBBi1BP), N-(1,1'-biphenyl-4-yl)-9,9-dimethyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9H-fluorene-2-amine (abbreviation: PCBASF), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF), N-(1,1'-biphenyl-4-yl)-9,9-dimethyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9H-fluorene-2-amine Examples of suitable amines include PCBBiF (abbreviation: PCBBiF), N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-4-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-3-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-2-amine, and N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-1-amine.

[0120] Note that the material having hole-transporting properties used in the composite material is more preferably a substance having a relatively deep HOMO level of -5.7 eV or more and -5.4 eV or less. When the material having hole-transporting properties used in the composite material has a relatively deep HOMO level, injection of holes into the hole-transport layer 112 becomes easy, and a light-emitting device with a long lifetime can be easily obtained. Furthermore, when the material having hole-transporting properties used in the composite material has a relatively deep HOMO level, hole induction is appropriately suppressed, and a light-emitting device with a long lifetime can be obtained.

[0121] The refractive index of the layer can be reduced by further mixing an alkali metal or alkaline earth metal fluoride into the composite material (preferably with an atomic ratio of fluorine atoms of 20% or more in the layer), which also allows a layer with a low refractive index to be formed inside the EL layer 103, thereby improving the external quantum efficiency of the light-emitting device.

[0122] By forming the hole injection layer 111, the hole injection property becomes good, and a light emitting device with a low driving voltage can be obtained.

[0123] Among substances having acceptor properties, organic compounds having acceptor properties are easy to use because they can be easily vapor-deposited and formed into a film.

[0124] The hole transport layer 112 is formed by including a material having a hole transport property. -6 cm 2 It is preferable that the hole mobility is / Vs or more.

[0125] Examples of the material having hole transport properties include 4,4'-bis[N-(1-naphthyl)-N-phenylamino]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-phenylfluoren-9-yl)triphenylamine (abbreviation: BPA), and 4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB). FLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviated as mBPAFLP), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCB Aromatic amines such as 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviated as PCBAF), and N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviated as PCBASF) Compounds with a benzophenone skeleton, compounds with a carbazole skeleton such as 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), and 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), and compounds with a benzophenone skeleton such as 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,Examples of suitable compounds include compounds having a thiophene skeleton, such as 8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III) and 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and compounds having a furan skeleton, such as 4,4′,4″-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II). Among the above, compounds having an aromatic amine skeleton and compounds having a carbazole skeleton are preferred because they have good reliability, high hole transport properties, and contribute to reducing driving voltage. Note that the substances listed as materials having hole transport properties used in the composite material of the hole injection layer 111 can also be suitably used as materials for forming the hole transport layer 112.

[0126] The light-emitting layer 113 contains a light-emitting substance and a host material. The light-emitting layer 113 may also contain other materials. Alternatively, the light-emitting layer 113 may be a laminate of two layers with different compositions.

[0127] The light-emitting substance may be a fluorescent substance, a phosphorescent substance, a substance that exhibits thermally activated delayed fluorescence (TADF), or other light-emitting substances. Note that one embodiment of the present invention is more preferably applicable to the case where the light-emitting layer 113 is a layer that exhibits fluorescent light, particularly a layer that exhibits blue fluorescent light.

[0128] Examples of materials that can be used as the fluorescent substance in the light-emitting layer 113 include the following: Other fluorescent substances can also be used.

[0129] 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine (abbreviation: PAP2BPy), 5,6-bis[4'-(10-phenyl-9-anthryl)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'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine )phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn), N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-diphenyl-N-[4-( 10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetra-tert-butylperylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), N,N''-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene)bis[N,N',N'-triphenyl-1,4-phenylenediamine] (abbreviation: DPABPA), N,9 -diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine (abbreviated as 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviated as 2DPAPPA), N,N,N',N',N'',N'',N''',N'''-octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviated as DBC1), Coumarin 30, N-(9,10-diphenyl-2-anthryl)-N,9-Diphenyl-9H-carbazol-3-amine (abbreviation: 2PCAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazol-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'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAB PhA), 9,10-bis(1,1'-biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracen-2-amine (abbreviation: 2YGABPhA), N,N,9-triphenylanthracen-9-amine (abbreviation: DPhAPhA), Coumarin 545T, N,N'-diphenylquinacridone, (abbreviation: DPQd), rubrene, 5,12-bis(1,1'-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6 -methyl-4H-pyran-4-ylidene)propanedinitrile (abbreviation: DCM1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM2), N,N,N',N'-tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine amine (abbreviation: p-mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB),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-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJTM), N,N'-diphenyl-N,N'-(1,6-pyren-diyl)bis[(6-phenylbenzo[b ]naphtho[1,2-d]furan)-8-amine] (abbreviated as 1,6BnfAPrn-03), 3,10-bis[N-(9-phenyl-9H-carbazol-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviated as 3,10PCA2Nbf(IV)-02), and 3,10-bis[N-(dibenzofuran-3-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviated as 3,10FrA2Nbf(IV)-02). In particular, condensed aromatic diamine compounds, such as pyrenediamine compounds, such as 1,6FLPAPrn, 1,6mMemFLPAPrn, and 1,6BnfAPrn-03, are preferred because of their high hole-trapping properties, excellent luminous efficiency, and reliability.

[0130] When a phosphorescent material is used as the light-emitting material in the light-emitting layer 113, examples of materials that can be used include the following.

[0131] Organometallic iridium complexes with a 4H-triazole skeleton, such as tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN2]phenyl-κC}iridium(III) (abbreviated as [Ir(mpptz-dmp)3]), tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III) (abbreviated as [Ir(Mptz)3]), and tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviated as [Ir(iPrptz-3b)3]), and tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III) Organometallic iridium complexes with a 1H-triazole skeleton, such as tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Mptz1-mp)3]) and tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Prptz1-Me)3]), organometallic iridium complexes with an imidazole skeleton, such as fac-tris[(1-2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviation: [Ir(iPrpmi)3]) and tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: [Ir(dmpimpt-Me)3]), and bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]iridium(III) tetrakis(1-pyrazolyl)borate (abbreviation: FIr6), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]iridium(III) picolinate (abbreviation: FIrpic), bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinato-N,C 2’}iridium(III) picolinate (abbreviation: [Ir(CF3ppy)2(pic)]), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’] Organometallic iridium complexes with phenylpyridine derivatives bearing electron-withdrawing groups as ligands, such as iridium(III) acetylacetonate (abbreviated as FIracac), are compounds that exhibit blue phosphorescence, with peak emission in the wavelength range from 440 nm to 520 nm.

[0132] Also, tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)3]), tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)3]), (acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)2(acac)]), (acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)2(acac)]), (acetylacetonato)bis[6-(2-norbornyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(nbppm)2(acac)]), (acetylacetonato)bis[5-methyl-6-( Organometallic iridium complexes with a pyrimidine skeleton, such as (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(mpmppm)2(acac)]) and (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm)2(acac)]), organometallic iridium complexes with a pyrazine skeleton, such as (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-Me)2(acac)]) and (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-iPr)2(acac)]), and tris(2-phenylpyridinato-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]quinolinato)iridium(III) acetylacetonate (abbreviation: [Ir(bzq)2(acac)]), tris(benzo[h]quinolinato)iridium(III) (abbreviation: [Ir(bzq)3]), tris(2-phenylquinolinato-N,C 2’ ) Iridium(III) (abbreviation: [Ir(pq)3]), bis(2-phenylquinolinato-N,C 2’ Examples include organometallic iridium complexes with a pyridine skeleton, such as iridium(III) acetylacetonate (abbreviated as [Ir(pq)2(acac)]), and rare earth metal complexes, such as tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviated as [Tb(acac)3(Phen)]). These compounds primarily exhibit green phosphorescence, with an emission peak in the wavelength range of 500 to 600 nm. Organometallic iridium complexes with a pyrimidine skeleton are particularly preferred, as they are remarkably superior in reliability and luminous efficiency.

[0133] In addition, organometallic iridium complexes having a pyrimidine skeleton, such as (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III) (abbreviation: [Ir(5mdppm)2(dibm)]), bis[4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(5mdppm)2(dpm)]), and bis[4,6-di(naphthalen-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(d1npm)2(dpm)]), Organometallic iridium complexes with a pyrazine skeleton, such as (acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: [Ir(tppr)2(acac)]), bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: [Ir(tppr)2(dpm)]), and (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: [Ir(Fdpq)2(acac)]), and tris(1-phenylisoquinolinato-N,C 2’ ) Iridium(III) (abbreviation: [Ir(piq)3]), bis(1-phenylisoquinolinato-N,C 2’ Examples include organometallic iridium complexes with a pyridine skeleton, such as iridium(III) acetylacetonate (abbreviated as [Ir(piq)2(acac)]), platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrinplatinum(II) (abbreviated as PtOEP), and rare earth metal complexes such as tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III) (abbreviated as [Eu(DBM)3(Phen)]) and tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III) (abbreviated as [Eu(TTA)3(Phen)]). These compounds exhibit red phosphorescence, with peak emission in the wavelength range of 600 to 700 nm. Furthermore, organometallic iridium complexes having a pyrazine skeleton can emit red light with good chromaticity.

[0134] In addition to the phosphorescent compounds described above, known phosphorescent compounds may be selected and used.

[0135] TADF materials include fullerene and its derivatives, acridine and its derivatives, eosin derivatives, etc. Also available are metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd). Examples of the metal-containing porphyrin include protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF2(OEP)), etioporphyrin-tin fluoride complex (SnF2(Etio I)), and octaethylporphyrin-platinum chloride complex (PtCl2OEP), all of which are shown in the following structural formulas.

[0136] [ka]

[0137] In addition, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 9-(4,6-diphenyl-1,3,5-triazin-2-yl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCzTzn), 9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCzPTzn), 2-[4-(10H-phenoxazin-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: P Heterocyclic compounds having either or both of a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring, such as 3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), and 10-phenyl-10H,10'H-spiro[acridine-9,9'-anthracene]-10'-one (abbreviation: ACRSA), can also be used. The heterocyclic compound has a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring, and therefore has high electron transport and hole transport properties, and is therefore preferred. Among the skeletons having a π-electron-deficient heteroaromatic ring, pyridine skeleton, diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), and triazine skeleton are preferred because they are stable and reliable. In particular, benzofuropyrimidine skeleton, benzothienopyrimidine skeleton, benzofuropyrazine skeleton, and benzothienopyrazine skeleton are preferred because they have high acceptor properties and good reliability. Furthermore, among the skeletons having a π-electron-rich heteroaromatic ring, acridine skeleton, phenoxazine skeleton, phenothiazine skeleton, furan skeleton, thiophene skeleton, and pyrrole skeleton are preferred because they are stable and reliable.The furan skeleton is preferably a dibenzofuran skeleton, and the thiophene skeleton is preferably a dibenzothiophene skeleton. The pyrrole skeleton is particularly preferably an indole skeleton, a carbazole skeleton, an indolocarbazole skeleton, a bicarbazole skeleton, or a 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole skeleton. Substances in which a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded are particularly preferred because the electron-donating ability of the π-electron-rich heteroaromatic ring and the electron-accepting ability of the π-electron-deficient heteroaromatic ring are both enhanced, thereby reducing the energy difference between the S1 level and the T1 level, thereby enabling efficient thermally activated delayed fluorescence. Instead of the π-electron-deficient heteroaromatic ring, an aromatic ring bonded to an electron-withdrawing group such as a cyano group may be used. The π-electron-rich skeleton may be, for example, an aromatic amine skeleton or a phenazine skeleton. Examples of usable π-electron-deficient skeletons include a xanthene skeleton, a thioxanthene dioxide skeleton, an oxadiazole skeleton, a triazole skeleton, an imidazole skeleton, an anthraquinone skeleton, a boron-containing skeleton such as phenylborane or boranthrene, an aromatic ring or heteroaromatic ring having a nitrile group or a cyano group such as benzonitrile or cyanobenzene, a carbonyl skeleton such as benzophenone, a phosphine oxide skeleton, a sulfone skeleton, etc. In this way, a π-electron-deficient skeleton or a π-electron-rich skeleton can be used in place of at least one of a π-electron-deficient heteroaromatic ring and a π-electron-rich heteroaromatic ring.

[0138] [ka]

[0139] TADF materials are materials with a small difference between the S1 and T1 levels, and have the ability to convert triplet excitation energy to singlet excitation energy through reverse intersystem crossing. Therefore, triplet excitation energy can be upconverted to singlet excitation energy (reverse intersystem crossing) using a small amount of thermal energy, allowing for efficient generation of a singlet excited state. Triplet excitation energy can also be converted into light emission.

[0140] Furthermore, exciplexes (also known as exciplexes), which form an excited state with two types of substances, have an extremely small difference between the S1 and T1 levels and function as TADF materials that can convert triplet excitation energy into singlet excitation energy.

[0141] The phosphorescence spectrum observed at low temperatures (for example, 77 K to 10 K) can be used as an indicator of the T1 level. For a TADF material, when a tangent line is drawn at the base of the fluorescence spectrum on the short wavelength side and the energy of the wavelength of the extrapolated line is defined as the S1 level, and a tangent line is drawn at the base of the phosphorescence spectrum on the short wavelength side and the energy of the wavelength of the extrapolated line is defined as the T1 level, the difference between S1 and T1 is preferably 0.3 eV or less, and more preferably 0.2 eV or less.

[0142] When a TADF material is used as a light-emitting material, the S1 level of the host material is preferably higher than the S1 level of the TADF material, and the T1 level of the host material is preferably higher than the T1 level of the TADF material.

[0143] As the host material of the light-emitting layer, various carrier transporting materials such as a material having an electron transporting property, a material having a hole transporting property, or the above-mentioned TADF material can be used.

[0144] As a material having hole transport properties, an organic compound having an amine skeleton or a π-electron-rich heteroaromatic ring skeleton is preferable. For example, 4,4'-bis[N-(1-naphthyl)-N-phenylamino]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-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP ... mBPAFLP), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (PCBANB), 4, Aromatic amine skeletons such as 4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), and N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF) and compounds with a carbazole skeleton such as 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), and 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), as well as 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,Examples of suitable materials include compounds having a thiophene skeleton, such as 8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III) and 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and compounds having a furan skeleton, such as 4,4′,4″-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II). Among the above, compounds having an aromatic amine skeleton and compounds having a carbazole skeleton are preferred because they have good reliability, high hole transport properties, and contribute to reducing driving voltage. The organic compounds listed as examples of materials having hole transport properties for the hole transport layer 112 can also be used. ,

[0145] Examples of materials having electron transport properties include metal complexes such as bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq2), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (abbreviation: BAlq), bis(8-quinolinolato)zinc(II) (abbreviation: Znq), bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO), and bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ), as well as organic compounds having a π-electron-deficient heteroaromatic ring skeleton. Examples of organic compounds having a π-electron-deficient heteroaromatic ring skeleton include 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-oxadiazole] (abbreviation: 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,2,4-triazole] ... [oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1 Heterocyclic compounds with polyazole skeletons such as H-benzimidazole (abbreviated as mDBTBIm-II), 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as 2mDBTPDBq-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviated as 2mDBTBPDBq-II), and 2-[3' Heterocyclic compounds with diazine skeletons such as 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), and 3,Heterocyclic compounds with a pyridine skeleton, such as 5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy) and 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), 2-[3'-(9,9-dimethyl-9H-fluoren-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'-spirobi(9 Examples of heterocyclic compounds having a triazine skeleton include 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-8-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn), and 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-6-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn-02). Among the above, heterocyclic compounds having a diazine skeleton, heterocyclic compounds having a pyridine skeleton, and heterocyclic compounds having a triazine skeleton are preferred because of their high reliability. In particular, heterocyclic compounds with a diazine (pyrimidine or pyrazine) skeleton and heterocyclic compounds with a triazine skeleton have high electron transport properties and contribute to reducing driving voltage.

[0146] The TADF materials that can be used as host materials are the same as those listed above. When a TADF material is used as a host material, the triplet excitation energy generated in the TADF material is converted to singlet excitation energy through reverse intersystem crossing, and the energy is then transferred to the light-emitting material, thereby improving the luminous efficiency of the light-emitting device. In this case, the TADF material functions as an energy donor, and the light-emitting material functions as an energy acceptor.

[0147] This is very effective when the luminescent material is a fluorescent luminescent material. In this case, in order to obtain high luminous efficiency, the S1 level of the TADF material is preferably higher than the S1 level of the fluorescent luminescent material. In addition, the T1 level of the TADF material is preferably higher than the S1 level of the fluorescent luminescent material. Therefore, the T1 level of the TADF material is preferably higher than the T1 level of the fluorescent luminescent material.

[0148] It is also preferable to use a TADF material that emits light at a wavelength that overlaps with the wavelength of the lowest-energy absorption band of the fluorescent material, as this allows for smooth transfer of excitation energy from the TADF material to the fluorescent material, resulting in efficient light emission.

[0149] Furthermore, to efficiently generate singlet excitation energy from triplet excitation energy through reverse intersystem crossing, carrier recombination is preferred in the TADF material. It is also preferable that the triplet excitation energy generated in the TADF material does not transfer to triplet excitation energy in the fluorescent material. To achieve this, the fluorescent material preferably has a protecting group around the luminophore (the skeleton responsible for light emission) of the fluorescent material. The protecting group is preferably a substituent without a π bond, and is preferably a saturated hydrocarbon. Specific examples include alkyl groups with 3 to 10 carbon atoms, substituted or unsubstituted cycloalkyl groups with 3 to 10 carbon atoms, and trialkylsilyl groups with 3 to 10 carbon atoms. Multiple protecting groups are even more preferred. Substituents without a π bond have poor carrier transport properties, allowing for the distance between the TADF material and the luminophore of the fluorescent material to be increased without significantly affecting carrier transport or carrier recombination. Here, the term "luminophore" refers to the atomic group (skeleton) responsible for light emission in the fluorescent material. The luminophore preferably has a skeleton having a π bond, preferably contains an aromatic ring, and preferably has a fused aromatic ring or a fused heteroaromatic ring. Examples of the fused aromatic ring or the fused heteroaromatic ring include a phenanthrene skeleton, a stilbene skeleton, an acridone skeleton, a phenoxazine skeleton, and a phenothiazine skeleton. In particular, fluorescent substances having a naphthalene skeleton, an anthracene skeleton, a fluorene skeleton, a chrysene skeleton, a triphenylene skeleton, a tetracene skeleton, a pyrene skeleton, a perylene skeleton, a coumarin skeleton, a quinacridone skeleton, or a naphthobisbenzofuran skeleton are preferred because of their high fluorescence quantum yield.

[0150] When a fluorescent emitting substance is used as the emitting substance, a material having an anthracene skeleton is suitable as the host material. Using a substance having an anthracene skeleton as the host material for a fluorescent emitting substance makes it possible to realize an emitting layer with both excellent luminous efficiency and durability. As a substance having an anthracene skeleton to be used as a host material, a diphenylanthracene skeleton, particularly a 9,10-diphenylanthracene skeleton, is preferred due to its chemical stability. Furthermore, host materials having a carbazole skeleton are preferred because of their enhanced hole injection and transport properties. However, host materials containing a benzocarbazole skeleton, in which a benzene ring is further condensed to carbazole, are even more preferred because their HOMO is approximately 0.1 eV shallower than that of carbazole, facilitating hole insertion. In particular, host materials containing a dibenzocarbazole skeleton are preferred because their HOMO is approximately 0.1 eV shallower than that of carbazole, facilitating hole insertion, and also exhibiting excellent hole transport properties and high heat resistance. Therefore, a more preferable host material is a substance having both a 9,10-diphenylanthracene skeleton and a carbazole skeleton (or a benzocarbazole skeleton or a dibenzocarbazole skeleton). From the viewpoint of the hole injection / transport property, a benzofluorene skeleton or a dibenzofluorene skeleton may be used instead of the carbazole skeleton. Examples of such a substance include 9-phenyl-3-[4-(10-phenyl-9-anthryl)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), and 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole. Examples include benzo[b]naphtho[1,2-d]furan (abbreviation: 2mBnfPPA), 9-phenyl-10-{4-(9-phenyl-9H-fluoren-9-yl)biphenyl-4'-yl}anthracene (abbreviation: FLPPA), and 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: αN-βNPAnth).In particular, CzPA, cgDBCzPA2mBnfPPA, and PCzPA are preferable choices because they exhibit very good properties.

[0151] The host material may be a mixture of multiple substances, and when a mixture of host materials is used, it is preferable to mix a material having electron-transporting properties with a material having hole-transporting properties. By mixing a material having electron-transporting properties with a material having hole-transporting properties, the transport properties of the light-emitting layer 113 can be easily adjusted, and the recombination region can also be easily controlled. The weight ratio of the content of the material having hole-transporting properties to the material having electron-transporting properties may be 1:19 to 19:1 (material having hole-transporting properties:material having electron-transporting properties).

[0152] A phosphorescent material can be used as part of the mixed material. The phosphorescent material can be used as an energy donor that provides excitation energy to a fluorescent material when the fluorescent material is used as a light-emitting material.

[0153] Furthermore, these mixed materials may form an exciplex. It is preferable to select a combination that forms an exciplex that emits light that overlaps with the wavelength of the lowest-energy absorption band of the light-emitting material, because this allows for smooth energy transfer and efficient light emission. Furthermore, using this structure is also preferable because it reduces the driving voltage.

[0154] At least one of the materials forming the exciplex may be a phosphorescent material, which allows efficient conversion of triplet excitation energy into singlet excitation energy through reverse intersystem crossing.

[0155] As a combination of materials that efficiently form an exciplex, it is preferable that the HOMO level of the hole-transporting material is equal to or higher than the HOMO level of the electron-transporting material. It is also preferable that the LUMO level of the hole-transporting material is equal to or higher than the LUMO level of the electron-transporting material. The LUMO and HOMO levels of the materials can be derived from the electrochemical properties (reduction potential and oxidation potential) of the materials measured by cyclic voltammetry (CV).

[0156] The formation of exciplexes can be confirmed by, for example, comparing the emission spectra of a hole-transporting material, an electron-transporting material, and a mixed film of these materials and observing the phenomenon that the emission spectrum of the mixed film is shifted to longer wavelengths than the emission spectra of each material (or has a new peak at longer wavelengths). Alternatively, it can be confirmed by comparing the transient photoluminescence (PL) of a hole-transporting material, the transient PL of an electron-transporting material, and a mixed film of these materials and observing differences in transient response, such as the transient PL lifetime of the mixed film having a longer-lived component or a larger proportion of delayed components than the transient PL lifetimes of the individual materials. The above-mentioned transient PL can also be interpreted as transient electroluminescence (EL). In other words, the formation of exciplexes can also be confirmed by comparing the transient EL of a hole-transporting material, the transient EL of an electron-transporting material, and a mixed film of these materials and observing differences in transient response.

[0157] The electron-transporting layer 114 is a layer containing a substance having an electron-transporting property. As the substance having an electron-transporting property, any of the substances exemplified above as the substance having an electron-transporting property that can be used as the host material can be used.

[0158] The electron transport layer 114 has an electron mobility of 1×10 when the square root of the electric field strength [V / cm] is 600. -7 cm 2 / Vs or more 5×10 -5 cm 2 / Vs or less. By reducing the electron transport property of the electron-transport layer 114, the amount of electrons injected into the light-emitting layer can be controlled, and the light-emitting layer can be prevented from becoming electron-excessive. This configuration is particularly preferable because it improves the lifetime when the hole-injection layer is formed of a composite material and the HOMO level of the material having hole-transport properties in the composite material is a substance having a relatively deep HOMO level of -5.7 eV or more and -5.4 eV or less. In this case, the HOMO level of the material having electron-transport properties is preferably -6.0 eV or more.

[0159] In addition, it is preferable that the alkali metal or the metal complex of the alkali metal in the electron transport layer 114 has a concentration difference (including a case where the difference is 0) in the thickness direction.

[0160] Between the electron transport layer 114 and the cathode 102, a layer containing an alkali metal or alkaline earth metal, such as lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF), or 8-hydroxyquinolinato-lithium (abbreviated as Liq), or a compound or complex thereof, may be provided as the electron injection layer 115. The electron injection layer 115 may be a layer made of a substance having electron transport properties containing an alkali metal or alkaline earth metal or a compound thereof, or an electride. Examples of the electride include a substance in which a high concentration of electrons is added to a mixed oxide of calcium and aluminum.

[0161] Note that a layer containing a fluoride of the alkali metal or alkaline earth metal in a concentration (50 wt % or more) sufficient to form a microcrystalline state in a substance having an electron transport property (preferably an organic compound having a bipyridine skeleton) can also be used as the electron-injection layer 115. Since this layer has a low refractive index, it is possible to provide a light-emitting device with better external quantum efficiency.

[0162] Furthermore, a charge generation layer 116 may be provided instead of the electron injection layer 115 of FIG. 1A (FIG. 1B). The charge generation layer 116 is a layer that can inject holes into a layer in contact with the cathode side of the layer and electrons into a layer in contact with the anode side of the layer by applying a potential. The charge generation layer 116 includes at least a P-type layer 117. The P-type layer 117 is preferably formed using the composite material listed above as a material that can form the hole injection layer 111. The P-type layer 117 may also be formed by laminating a film containing an acceptor material and a film containing a hole transport material, both of which are materials that form the composite material. By applying a potential to the P-type layer 117, electrons are injected into the electron transport layer 114 and holes are injected into the cathode 102, and the light-emitting device operates.

[0163] It is preferable that the charge generating layer 116 be provided with either or both of an electron relay layer 118 and an electron injection buffer layer 119 in addition to the P-type layer 117 .

[0164] The electron relay layer 118 contains at least a substance having electron transport properties and has the function of preventing interaction between the electron injection buffer layer 119 and the P-type layer 117 and smoothly transferring electrons. The LUMO level of the substance having electron transport properties contained in the electron relay layer 118 is preferably between the LUMO level of the acceptor substance in the P-type layer 117 and the LUMO level of the substance contained in the layer of the electron transport layer 114 that is in contact with the charge generation layer 116. The specific energy level of the LUMO level of the substance having electron transport properties used in the electron relay layer 118 is −5.0 eV or higher, preferably −5.0 eV or higher and −3.0 eV or lower. Note that the substance having electron transport properties used in the electron relay layer 118 is preferably a phthalocyanine-based material or a metal complex having a metal-oxygen bond and an aromatic ligand.

[0165] The electron injection buffer layer 119 can be made of a material with high electron injection properties, such as alkali metals, alkaline earth metals, rare earth metals, and compounds thereof (alkali metal compounds (including oxides such as lithium oxide, halides, and carbonates such as lithium carbonate and cesium carbonate), alkaline earth metal compounds (including oxides, halides, and carbonates), or rare earth metal compounds (including oxides, halides, and carbonates)).

[0166] Furthermore, when the electron injection buffer layer 119 is formed to contain a substance having electron transport properties and a donor substance, examples of the donor substance that can be used include alkali metals, alkaline earth metals, rare earth metals, and compounds thereof (alkali metal compounds (including oxides such as lithium oxide, halides, and carbonates such as lithium carbonate and cesium carbonate), alkaline earth metal compounds (including oxides, halides, and carbonates), and rare earth metal compounds (including oxides, halides, and carbonates)), as well as organic compounds such as tetrathianaphthacene (abbreviation: TTN), nickelocene, and decamethylnickelocene.

[0167] The substance having an electron-transporting property can be formed using the same material as the material for forming the electron-transporting layer 114 described above. Since the material is an organic compound with a low refractive index, by using the material for the electron-injection buffer layer 119, a light-emitting device with good external quantum efficiency can be obtained.

[0168] Materials that can be used to form the cathode 102 include metals, alloys, electrically conductive compounds, and mixtures thereof that have a low work function (specifically, 3.8 eV or less). Specific examples of such cathode materials include alkali metals such as lithium (Li) and cesium (Cs), elements belonging to Group 1 or Group 2 of the periodic table such as magnesium (Mg), calcium (Ca), and strontium (Sr), alloys containing these (MgAg, AlLi), rare earth metals such as europium (Eu) and ytterbium (Yb), and alloys containing these. However, by providing an electron injection layer between the cathode 102 and the electron transport layer, various conductive materials can be used for the cathode 102, regardless of the magnitude of the work function, such as Al, Ag, ITO, and indium oxide-tin oxide containing silicon or silicon oxide.

[0169] When the cathode 102 is made of a material that is transparent to visible light, a light-emitting device that emits light from the cathode side can be formed, as shown in Fig. 1D. When the anode 101 is formed on the substrate side, this light-emitting device can be a so-called top-emission type light-emitting device.

[0170] These conductive materials can be formed into films by dry methods such as vacuum deposition and sputtering, inkjet methods, spin coating methods, etc. Alternatively, they may be formed by wet methods using a sol-gel method, or by wet methods using a paste of a metal material.

[0171] In addition, various methods, whether dry or wet, can be used to form the EL layer 103. For example, vacuum deposition, gravure printing, offset printing, screen printing, inkjet printing, or spin coating may be used.

[0172] Furthermore, the above-mentioned electrodes or layers may be formed using different film formation methods.

[0173] The configuration of the layer provided between the anode 101 and the cathode 102 is not limited to the above. However, a configuration in which a light-emitting region where holes and electrons recombine is provided at a location away from the anode 101 and the cathode 102 is preferable, so as to suppress quenching caused by the proximity of the light-emitting region to the metals used in the electrodes and the carrier injection layer.

[0174] Furthermore, the hole transport layer and electron transport layer in contact with the light-emitting layer 113, particularly the carrier transport layer close to the recombination region in the light-emitting layer 113, are preferably made of a material having a band gap larger than the band gap of the light-emitting material constituting the light-emitting layer or the light-emitting material contained in the light-emitting layer, in order to suppress energy transfer from excitons generated in the light-emitting layer.

[0175] Next, an embodiment of a light-emitting device (also called a stacked element or tandem element) having a configuration in which multiple light-emitting units are stacked will be described. This light-emitting device has multiple light-emitting units between an anode and a cathode. One light-emitting unit has a configuration substantially similar to that of the EL layer 103 shown in FIG. 1A. In other words, a tandem element is a light-emitting device having multiple light-emitting units, and the light-emitting device shown in FIG. 1A or 1B can be said to be a light-emitting device having one light-emitting unit.

[0176] In a tandem element, a first light-emitting unit and a second light-emitting unit are stacked between an anode and a cathode, and a charge generation layer is provided between the first light-emitting unit and the second light-emitting unit. The anode and cathode correspond to anode 101 and cathode 102 in FIG. 1A, respectively, and the same as those described in the description of FIG. 1A can be applied. Furthermore, the first light-emitting unit and the second light-emitting unit may have the same or different configurations.

[0177] The charge generation layer in a tandem element has the function of injecting electrons into one light-emitting unit and injecting holes into the other light-emitting unit when a voltage is applied between the anode and the cathode. In other words, when a voltage is applied so that the potential of the anode is higher than the potential of the cathode, the charge generation layer may inject electrons into the first light-emitting unit and inject holes into the second light-emitting unit.

[0178] The charge generation layer is preferably formed to have the same structure as the charge generation layer 116 described in FIG. 1B. A composite material of an organic compound and a metal oxide has excellent carrier injection and carrier transport properties, and therefore can achieve low-voltage driving and low-current driving. Note that when the anode side surface of the light-emitting unit is in contact with the charge generation layer, the charge generation layer can also serve as the hole injection layer of the light-emitting unit, and therefore the light-emitting unit does not need to be provided with a hole injection layer.

[0179] Furthermore, when the electron injection buffer layer 119 is provided in the charge generation layer of a tandem element, the electron injection buffer layer 119 plays the role of an electron injection layer in the light-emitting unit on the anode side, and therefore it is not necessarily required to form an electron injection layer in the light-emitting unit on the anode side.

[0180] While the above describes a tandem element having two light-emitting units, the same can be applied to a tandem element having three or more stacked light-emitting units. By arranging multiple light-emitting units between a pair of electrodes and separating them with a charge-generating layer, it is possible to achieve a device that emits high-intensity light while maintaining a low current density, and that has a long lifespan. It is also possible to realize a light-emitting device that can be driven at a low voltage and consumes little power.

[0181] Furthermore, by making each light-emitting unit emit a different light color, the light-emitting device as a whole can emit light of a desired color. For example, in a light-emitting device having two light-emitting units, it is possible to obtain a light-emitting device that emits white light as a whole by obtaining red and green light from the first light-emitting unit and blue light from the second light-emitting unit.

[0182] The above-described EL layer 103, the first light-emitting unit, the second light-emitting unit, the charge generation layer, and other layers and electrodes can be formed by, for example, vapor deposition (including vacuum deposition), droplet discharge (also called ink-jet method), coating, gravure printing, etc. They may also contain low-molecular-weight materials, medium-molecular-weight materials (including oligomers and dendrimers), or polymer materials.

[0183] This embodiment mode can be freely combined with other embodiment modes.

[0184] (Embodiment 2) In this embodiment, a light-emitting apparatus using the light-emitting device described in Embodiment 1 will be described.

[0185] In this embodiment, a light-emitting device manufactured using the light-emitting device described in Embodiment 1 will be described with reference to FIGS. 2A and 2B. FIG. 2A is a top view showing the light-emitting device, and FIG. 2B is a cross-sectional view taken along dashed lines AB and CD shown in FIG. 2A. This light-emitting device includes a driver circuit section (source line driver circuit) 601, a pixel section 602, and a driver circuit section (gate line driver circuit) 603, all of which are shown by dotted lines, to control light emission from the light-emitting device. Also, 604 denotes a sealing substrate, 605 denotes a sealant, and the inside surrounded by the sealant 605 forms a space 607.

[0186] The routing wiring 608 is wiring for transmitting signals input to the source line driver circuit 601 and the gate line driver circuit 603, and receives video signals, clock signals, start signals, reset signals, etc. from an FPC (flexible printed circuit) 609, which serves as an external input terminal. Although only the FPC is shown here, a printed wiring board (PWB) may be attached to this FPC. In this specification, the light-emitting device includes not only the light-emitting device itself, but also a state in which an FPC or PWB is attached to it.

[0187] Next, the cross-sectional structure will be described with reference to Fig. 2B. A driver circuit section and a pixel section are formed on an element substrate 610, but here, a source line driver circuit 601, which is the driver circuit section, and one pixel in a pixel section 602 are shown.

[0188] The element substrate 610 may be made of a substrate made of glass, quartz, organic resin, metal, alloy, semiconductor, or a plastic substrate made of FRP (Fiber Reinforced Plastics), PVF (Polyvinyl Fluoride), polyester, acrylic resin, or the like.

[0189] The structure of the transistors used in the pixels and driver circuits is not particularly limited. For example, they may be inverted staggered transistors or staggered transistors. Furthermore, they may be top-gate or bottom-gate transistors. The semiconductor material used for the transistors is not particularly limited, and examples thereof include silicon, germanium, silicon carbide, and gallium nitride. Alternatively, an oxide semiconductor containing at least one of indium, gallium, and zinc, such as an In-Ga-Zn-based metal oxide, may be used.

[0190] The crystallinity of a semiconductor material used for a transistor is not particularly limited, and any of an amorphous semiconductor and a crystalline semiconductor (a microcrystalline semiconductor, a polycrystalline semiconductor, a single crystal semiconductor, or a semiconductor having a crystalline region in part) may be used. The use of a crystalline semiconductor is preferable because it can suppress deterioration of transistor characteristics.

[0191] Here, it is preferable to use an oxide semiconductor for semiconductor devices such as transistors provided in the pixels and driver circuits, as well as transistors used in touch sensors, which will be described later. In particular, it is preferable to use an oxide semiconductor having a wider band gap than silicon. By using an oxide semiconductor having a wider band gap than silicon, the current in the off state of the transistor can be reduced.

[0192] The oxide semiconductor preferably contains at least indium (In) or zinc (Zn), and more preferably contains an oxide represented by In-M-Zn oxide (M is a metal such as Al, Ti, Ga, Ge, Y, Zr, Sn, La, Ce, or Hf).

[0193] In particular, it is preferable to use, as the semiconductor layer, an oxide semiconductor film having a plurality of crystal parts whose c-axes are oriented perpendicular to the surface on which the semiconductor layer is formed or the top surface of the semiconductor layer and which does not have grain boundaries between adjacent crystal parts.

[0194] By using such a material for the semiconductor layer, fluctuations in electrical characteristics are suppressed, and a highly reliable transistor can be realized.

[0195] Furthermore, a transistor having the above-described semiconductor layer can retain charge stored in a capacitor through the transistor for a long period of time due to its low off-state current. By applying such a transistor to a pixel, it is possible to stop the driver circuit while maintaining the gray level of an image displayed in each display region. As a result, an electronic device with extremely low power consumption can be realized.

[0196] To stabilize the characteristics of the transistor, it is preferable to provide an underlayer film. The underlayer film can be formed as a single layer or a multilayer using an inorganic insulating film such as a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a silicon nitride oxide film. The underlayer film can be formed by a sputtering method, a CVD (Chemical Vapor Deposition) method (such as a plasma CVD method, a thermal CVD method, or a MOCVD (Metal Organic CVD) method), an ALD (Atomic Layer Deposition) method, a coating method, a printing method, or the like. Note that the underlayer film need not be provided if it is not necessary.

[0197] Note that FET 623 represents one of the transistors formed in the drive circuit section 601. The drive circuit may be formed of various CMOS circuits, PMOS circuits, or NMOS circuits. In addition, although this embodiment shows a driver-integrated type in which the drive circuit is formed on a substrate, this is not necessarily required, and the drive circuit may also be formed externally rather than on the substrate.

[0198] Furthermore, the pixel section 602 is formed by a plurality of pixels each including a switching FET 611, a current control FET 612, and an anode 613 electrically connected to the drain of the FET, but is not limited to this, and the pixel section may be formed by combining three or more FETs and a capacitance element.

[0199] An insulator 614 is formed to cover the end of the anode 613. Here, it can be formed by using a positive photosensitive acrylic resin film.

[0200] Furthermore, in order to improve the coverage of an EL layer or the like to be formed later, a curved surface having a curvature is formed at the upper or lower end of the insulator 614. For example, when a positive photosensitive acrylic resin is used as the material for the insulator 614, it is preferable that only the upper end of the insulator 614 has a curved surface having a radius of curvature (0.2 μm to 3 μm). Furthermore, either a negative photosensitive resin or a positive photosensitive resin can be used as the insulator 614.

[0201] An EL layer 616 and a cathode 617 are formed on the anode 613. It is desirable to use a material with a large work function for the anode 613. For example, a single layer film such as an ITO film, an indium tin oxide film containing silicon, an indium oxide film containing 2 to 20 wt % zinc oxide, a titanium nitride film, a chromium film, a tungsten film, a Zn film, or a Pt film can be used. It is also possible to use a laminated structure of a titanium nitride film and a film mainly composed of aluminum, or a three-layer structure of a titanium nitride film, a film mainly composed of aluminum, and a titanium nitride film. The laminated structure provides low resistance as wiring, good ohmic contact, and the anode can function well.

[0202] The EL layer 616 is formed by various methods such as a vapor deposition method using a vapor deposition mask, an inkjet method, or a spin coating method. The EL layer 616 includes the components described in Embodiment 1. Other materials constituting the EL layer 616 may be low-molecular compounds or high-molecular compounds (including oligomers and dendrimers).

[0203] Furthermore, it is preferable to use a material with a small work function (Al, Mg, Li, Ca, or alloys or compounds thereof (MgAg, MgIn, AlLi, etc.)) as a material formed on the EL layer 616. When light generated in the EL layer 616 is transmitted through the cathode 617, it is preferable to use a laminate of a thin metal thin film and a transparent conductive film (ITO, indium oxide containing 2 to 20 wt % zinc oxide, indium tin oxide containing silicon, zinc oxide (ZnO), etc.) as the cathode 617.

[0204] Note that a light-emitting device is formed with the anode 613, the EL layer 616, and the cathode 617. The light-emitting device is the light-emitting device described in Embodiment 1. Note that a pixel portion is formed with a plurality of light-emitting devices, but the light-emitting device in this embodiment may include both the light-emitting device described in Embodiment 1 and light-emitting devices having other structures.

[0205] Furthermore, by bonding the sealing substrate 604 to the element substrate 610 with a sealant 605, a structure is formed in which a light-emitting device 618 is provided in a space 607 surrounded by the element substrate 610, the sealing substrate 604, and the sealant 605. The space 607 is filled with a filler, which may be filled with an inert gas (nitrogen, argon, etc.) or a sealant. A recess is formed in the sealing substrate and a desiccant is provided therein, which is a preferable configuration because it can suppress deterioration due to the influence of moisture.

[0206] It is preferable to use epoxy resin or glass frit for the sealing material 605. It is also desirable that these materials are as moisture and oxygen impermeable as possible. In addition to glass and quartz substrates, plastic substrates made of FRP (Fiber Reinforced Plastics), PVF (Polyvinyl Fluoride), polyester, acrylic resin, etc. can be used for the sealing substrate 604.

[0207] Although not shown in Figures 2A and 2B, a protective film may be provided on the cathode. The protective film may be formed of an organic resin film or an inorganic insulating film. The protective film may also be formed so as to cover the exposed portion of the sealing material 605. The protective film may also be provided so as to cover the surfaces and side surfaces of the pair of substrates, the exposed side surfaces of the sealing layer, the insulating layer, etc.

[0208] The protective film can be made of a material that is impermeable to impurities such as water, and therefore can effectively prevent impurities such as water from diffusing from the outside to the inside.

[0209] The protective film may be made of an oxide, a nitride, a fluoride, a sulfide, a ternary compound, a metal, a polymer, or the like. For example, a material containing aluminum oxide, hafnium oxide, hafnium silicate, lanthanum oxide, silicon oxide, strontium titanate, tantalum oxide, titanium oxide, zinc oxide, niobium oxide, zirconium oxide, tin oxide, yttrium oxide, cerium oxide, scandium oxide, erbium oxide, vanadium oxide, indium oxide, or the like; a material containing aluminum nitride, hafnium nitride, silicon nitride, tantalum nitride, titanium nitride, niobium nitride, molybdenum nitride, zirconium nitride, gallium nitride, or the like; a nitride containing titanium and aluminum; an oxide containing titanium and aluminum; an oxide containing aluminum and zinc; a sulfide containing manganese and zinc; a sulfide containing cerium and strontium; an oxide containing erbium and aluminum; or an oxide containing yttrium and zirconium.

[0210] The protective film is preferably formed using a film formation method that provides good step coverage. One such method is atomic layer deposition (ALD). It is preferable to use a material that can be formed using the ALD method for the protective film. By using the ALD method, it is possible to form a dense protective film with reduced defects such as cracks and pinholes, or with a uniform thickness. In addition, it is possible to reduce damage to the workpiece when forming the protective film.

[0211] For example, by forming a protective film using the ALD method, it is possible to form a uniform protective film with few defects on surfaces with complex uneven shapes, as well as on the top, side, and back surfaces of a touch panel.

[0212] In the above manner, a light-emitting device manufactured using the light-emitting device described in Embodiment 1 can be obtained.

[0213] The light-emitting device in this embodiment can have favorable characteristics because it uses the light-emitting device described in Embodiment 1. Specifically, the light-emitting device described in Embodiment 1 has favorable luminous efficiency, and therefore can have low power consumption.

[0214] 3A and 3B show an example of a light-emitting device in which a white-emitting light-emitting device is formed and a full color display is achieved by providing a colored layer (color filter), etc. Fig. 3A shows a substrate 1001, a base insulating film 1002, a gate insulating film 1003, gate electrodes 1006, 1007, and 1008, a first interlayer insulating film 1020, a second interlayer insulating film 1021, a peripheral portion 1042, a pixel portion 1040, a driving circuit portion 1041, anodes 1024W, 1024R, 1024G, and 1024B of the light-emitting device, a partition wall 1025, an EL layer 1028, a cathode 1029 of the light-emitting device, a sealing substrate 1031, a sealant 1032, etc.

[0215] 3A, the colored layers (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B) are provided on a transparent base material 1033. A black matrix 1035 may also be provided. The transparent base material 1033 on which the colored layers and black matrix are provided is aligned and fixed to the substrate 1001. The colored layers and black matrix 1035 are covered with an overcoat layer 1036. Also, in FIG. 3A, there are light-emitting layers from which light does not pass through the colored layers and exits to the outside, and light-emitting layers from which light passes through the colored layers of each color and exits to the outside. Light that does not pass through the colored layers is white, and light that passes through the colored layers is red, green, and blue, so that an image can be displayed using four color pixels.

[0216] 3B shows an example in which colored layers (a red colored layer 1034R, a green colored layer 1034G, and a blue colored layer 1034B) are formed between the gate insulating film 1003 and the first interlayer insulating film 1020. In this way, the colored layers may be provided between the substrate 1001 and the sealing substrate 1031.

[0217] Furthermore, the light-emitting device described above has a structure in which light is extracted from the substrate 1001 side on which the FET is formed (bottom emission type), but it may also have a structure in which light is extracted from the sealing substrate 1031 side (top emission type). A cross-sectional view of a top emission type light-emitting device is shown in FIG. 4. In this case, a light-opaque substrate can be used as the substrate 1001. The process is the same as for a bottom emission type light-emitting device up to the formation of a connection electrode that connects the FET and the anode of the light-emitting device. Thereafter, a third interlayer insulating film 1037 is formed to cover the electrode 1022. This insulating film may also serve as a planarizing film. The third interlayer insulating film 1037 can be formed using the same material as the second interlayer insulating film, as well as other known materials.

[0218] Although the anodes 1024W, 1024R, 1024G, and 1024B of the light-emitting device are referred to as anodes in this example, they may be cathodes. Furthermore, in the case of a top-emission light-emitting device such as that shown in FIG. 4, it is preferable that the anodes be reflective electrodes. The EL layer 1028 has the same configuration as that described for the EL layer 103 in the first embodiment, and has an element structure that allows white light emission.

[0219] In the top-emission structure shown in FIG. 4, sealing can be performed using a sealing substrate 1031 provided with colored layers (a red colored layer 1034R, a green colored layer 1034G, and a blue colored layer 1034B). The sealing substrate 1031 may be provided with a black matrix 1035 positioned between pixels. The colored layers (the red colored layer 1034R, the green colored layer 1034G, and the blue colored layer 1034B) and the black matrix may be covered with an overcoat layer 1036. Note that a light-transmitting substrate is used as the sealing substrate 1031. In addition, although an example of full-color display using four colors, red, green, blue, and white, is shown here, the present invention is not particularly limited, and full-color display using four colors, red, yellow, green, and blue, or three colors, red, green, and blue, may also be performed.

[0220] A microcavity structure is suitable for use in top-emission light-emitting devices. A light-emitting device with a microcavity structure can be obtained by using a reflective electrode as the anode and a semi-transparent / semi-reflective electrode as the cathode. At least an EL layer is present between the reflective electrode and the semi-transparent / semi-reflective electrode, and at least an emissive layer that serves as the light-emitting region is present.

[0221] The reflectance of the reflective electrode to visible light is 40% to 100%, preferably 70% to 100%, and the resistivity is 1×10 -2 The semi-transmitting and semi-reflective electrode has a visible light reflectance of 20% to 80%, preferably 40% to 70%, and a resistivity of 1×10 -2 It is assumed that the film has a resistance of Ωcm or less.

[0222] The light emitted from the light-emitting layer included in the EL layer is reflected by the reflective electrode and the semi-transmissive and semi-reflective electrode, causing resonance.

[0223] In this light-emitting device, the optical distance between the reflective electrode and the semi-transparent / semi-reflective electrode can be changed by changing the thickness of the transparent conductive film, the composite material described above, the carrier transport material, etc. This makes it possible to intensify light with resonant wavelengths and attenuate light with non-resonant wavelengths between the reflective electrode and the semi-transparent / semi-reflective electrode.

[0224] Note that, since the light reflected by the reflective electrode and returned (first reflected light) significantly interferes with the light (first incident light) that directly enters the semi-transmissive-semi-reflective electrode from the light-emitting layer, it is preferable to adjust the optical distance between the reflective electrode and the light-emitting layer to (2n-1)λ / 4 (where n is a natural number greater than or equal to 1, and λ is the wavelength of the emitted light to be amplified). By adjusting this optical distance, the phases of the first reflected light and the first incident light can be matched, thereby further amplifying the light emitted from the light-emitting layer.

[0225] In the above configuration, the EL layer may have a structure having multiple light-emitting layers or a structure having a single light-emitting layer. For example, it may be combined with the above-mentioned tandem light-emitting device configuration, in which multiple EL layers are provided in one light-emitting device with a charge-generating layer sandwiched therebetween, and one or more light-emitting layers are formed in each EL layer.

[0226] The microcavity structure makes it possible to increase the light emission intensity of specific wavelengths in the front direction, thereby reducing power consumption. In the case of a light-emitting device that displays images using four sub-pixels of red, yellow, green, and blue, not only is the yellow light emitted effective in improving brightness, but the microcavity structure that matches the wavelength of each color can be applied to all sub-pixels, resulting in a light-emitting device with good characteristics.

[0227] The light-emitting device in this embodiment can have favorable characteristics because it uses the light-emitting device described in Embodiment 1. Specifically, the light-emitting device described in Embodiment 1 has favorable luminous efficiency, and therefore can have low power consumption.

[0228] Up to this point, we have explained active matrix light-emitting devices. From here on, we will explain passive matrix light-emitting devices. FIGS. 5A and 5B show a passive matrix light-emitting device manufactured by applying the present invention. FIG. 5A is a perspective view of the light-emitting device, and FIG. 5B is a cross-sectional view of FIG. 5A taken along the dashed-dotted line XY. In FIG. 5, an EL layer 955 is provided between an electrode 952 and an electrode 956 on a substrate 951. The edge of the electrode 952 is covered with an insulating layer 953. A partition layer 954 is provided on the insulating layer 953. The sidewalls of the partition layer 954 are inclined such that the distance between one sidewall and the other sidewall narrows as the distance approaches the substrate surface. That is, the cross section of the partition layer 954 in the short side direction is trapezoidal, and the bottom side (the side facing the same direction as the surface of the insulating layer 953 and in contact with the insulating layer 953) is shorter than the top side (the side facing the same direction as the surface of the insulating layer 953 and not in contact with the insulating layer 953). By providing the partition layer 954 in this manner, defects in the light-emitting device due to static electricity or the like can be prevented. Furthermore, the light-emitting device described in Embodiment 1 is used in a passive matrix light-emitting device, and the light-emitting device can be highly reliable or consumes less power.

[0229] The light emitting device described above is capable of individually controlling a large number of minute light emitting devices arranged in a matrix, and is therefore suitable for use as a display device for displaying images.

[0230] This embodiment mode can be freely combined with other embodiment modes.

[0231] (Embodiment 3) In this embodiment, an example in which the light-emitting device described in Embodiment 1 is used as a lighting device will be described with reference to Fig. 6. Fig. 6B is a top view of the lighting device, and Fig. 6A is a cross-sectional view taken along line ef shown in Fig. 6B.

[0232] In the lighting device of this embodiment, an anode 401 is formed on a light-transmitting substrate 400, which serves as a support. The anode 401 corresponds to the anode 101 in Embodiment 1. When light is extracted from the anode 401 side, the anode 401 is formed from a light-transmitting material.

[0233] A pad 412 for supplying a voltage to the cathode 404 is formed on the substrate 400 .

[0234] An EL layer 403 is formed on the anode 401. The EL layer 403 corresponds to the configuration of the EL layer 103 in the first embodiment. For details of these configurations, please refer to the description therein.

[0235] Cathode 404 is formed to cover EL layer 403. Cathode 404 corresponds to cathode 102 in Embodiment 1. When light is extracted from the anode 401 side, cathode 404 is formed of a material with high reflectivity. Cathode 404 is connected to pad 412 to supply voltage.

[0236] As described above, the lighting device described in this embodiment has a light-emitting device including the anode 401, the EL layer 403, and the cathode 404. Since the light-emitting device has high luminous efficiency, the lighting device in this embodiment can be a lighting device with low power consumption.

[0237] The lighting device is completed by bonding and sealing substrate 407, on which the light-emitting device having the above configuration is formed, to substrate 400 using sealants 405 and 406. Either sealant 405 or 406 can be used. Also, a desiccant can be mixed into inner sealant 406 (not shown in FIG. 6B), which can absorb moisture and improve reliability.

[0238] Furthermore, an external input terminal can be formed by extending a portion of the pad 412 and the anode 401 outside the sealing materials 405 and 406. An IC chip 420 equipped with a converter or the like may also be provided thereon.

[0239] As described above, the lighting device described in this embodiment uses the light-emitting device described in Embodiment 1 as an EL element, and can be a light-emitting device with low power consumption.

[0240] This embodiment mode can be freely combined with other embodiment modes.

[0241] (Fourth embodiment) In this embodiment, an example of an electronic device including the light-emitting device described in Embodiment 1 as a part thereof will be described. The light-emitting device described in Embodiment 1 has good light-emitting efficiency and low power consumption. As a result, the electronic device described in this embodiment can be an electronic device having a light-emitting portion with low power consumption.

[0242] Examples of electronic devices to which the light-emitting devices are applied include television sets (also called televisions or television receivers), computer monitors, digital cameras, digital video cameras, digital photo frames, mobile phones (also called mobile phones or mobile phone devices), portable game machines, personal digital assistants, sound players, large game machines such as pachinko machines, etc. Specific examples of these electronic devices are shown below.

[0243] 7A illustrates an example of a television set. The television set has a display portion 7103 incorporated in a housing 7101. Here, the housing 7101 is supported by a stand 7105. The display portion 7103 can display images, and the light-emitting devices described in Embodiment 1 are arranged in a matrix.

[0244] The television set can be operated using operation switches provided on the housing 7101 or a separate remote control 7110. Channels and volume can be controlled using operation keys 7109 provided on the remote control 7110, and images displayed on the display portion 7103 can be controlled. The remote control 7110 may be provided with a display portion 7107 that displays information output from the remote control 7110. Note that the light-emitting devices described in Embodiment 1 arranged in a matrix can also be applied to the display portion 7107.

[0245] The television device is configured to include a receiver, a modem, etc. The receiver can receive general television broadcasts, and by connecting to a wired or wireless communication network via the modem, it is also possible to perform one-way (from sender to receiver) or two-way (between sender and receiver, or between receivers, etc.) information communication.

[0246] FIG. 7B1 shows a computer including a main body 7201, a housing 7202, a display portion 7203, a keyboard 7204, an external connection port 7205, a pointing device 7206, and the like. This computer is manufactured by using the light-emitting devices described in Embodiment 1 arranged in a matrix for the display portion 7203. The computer in FIG. 7B1 may have a configuration as shown in FIG. 7B2. The computer in FIG. 7B2 is provided with a display portion 7210 instead of the keyboard 7204 and the pointing device 7206. The display portion 7210 is a touch panel type, and input can be performed by operating an input display displayed on the display portion 7210 with a finger or a dedicated pen. The display portion 7210 can display not only an input display but also other images. The display portion 7203 may also be a touch panel. The two screens are connected by a hinge, which can prevent the screens from being scratched or broken during storage or transportation.

[0247] 7C shows an example of a mobile terminal. The mobile phone includes a display portion 7402 built into a housing 7401, operation buttons 7403, an external connection port 7404, a speaker 7405, a microphone 7406, and the like. Note that the mobile phone has the display portion 7402 in which the light-emitting devices described in Embodiment 1 are arranged in a matrix.

[0248] 7C can be configured so that information can be input by touching the display portion 7402 with a finger or the like. In this case, operations such as making a call or creating an e-mail can be performed by touching the display portion 7402 with a finger or the like.

[0249] The screen of the display unit 7402 has three main modes. The first is a display mode that mainly displays images, the second is an input mode that mainly inputs information such as characters, and the third is a display+input mode that combines the display mode and the input mode.

[0250] For example, when making a call or creating an e-mail, the display portion 7402 may be set to a character input mode mainly for inputting characters, and characters displayed on the screen may be input. In this case, it is preferable to display a keyboard or number buttons on most of the screen of the display portion 7402.

[0251] Furthermore, by providing a detection device having a sensor for detecting tilt, such as a gyroscope or an acceleration sensor, inside the mobile terminal, the orientation of the mobile terminal (portrait or landscape) can be determined and the screen display of the display portion 7402 can be automatically switched.

[0252] The screen mode can be switched by touching the display portion 7402 or by operating the operation buttons 7403 on the housing 7401. The screen mode can also be switched depending on the type of image displayed on the display portion 7402. For example, if the image signal to be displayed on the display portion is moving image data, the display mode is selected, and if it is text data, the input mode is selected.

[0253] In addition, in the input mode, a signal detected by an optical sensor of the display portion 7402 may be detected, and if there is no input by touch operation on the display portion 7402 for a certain period of time, the screen mode may be controlled to switch from the input mode to the display mode.

[0254] The display portion 7402 can also function as an image sensor. For example, personal authentication can be performed by touching the display portion 7402 with a palm or a finger to capture an image of a palm print, fingerprint, or the like. Furthermore, by using a backlight that emits near-infrared light or a sensing light source that emits near-infrared light for the display portion, finger veins, palm veins, or the like can also be captured.

[0255] Note that the structure described in this embodiment mode can be used by appropriately combining the structures described in any of Embodiment Modes 1 to 4.

[0256] As described above, the light-emitting device having the light-emitting device described in Embodiment 1 or 2 has a very wide range of application, and this light-emitting device can be applied to electronic devices in a wide range of fields. By using the light-emitting device described in Embodiment 1 or 2, electronic devices with low power consumption can be obtained.

[0257] FIG. 8A is a schematic diagram showing an example of a cleaning robot.

[0258] The cleaning robot 5100 has a display 5101 arranged on its top surface, multiple cameras 5102 arranged on its side, a brush 5103, and an operation button 5104. Although not shown, the cleaning robot 5100 is also provided with tires, a suction port, and the like on its bottom surface. The cleaning robot 5100 also has various other sensors such as an infrared sensor, an ultrasonic sensor, an acceleration sensor, a piezoelectric sensor, an optical sensor, and a gyro sensor. The cleaning robot 5100 also has wireless communication means.

[0259] The cleaning robot 5100 can move by itself, detect dust 5120, and suck up the dust from a suction port provided on the bottom surface.

[0260] Furthermore, the cleaning robot 5100 can analyze the image captured by the camera 5102 to determine whether there are any obstacles such as walls, furniture, or steps. Furthermore, if the image analysis detects an object that may become tangled in the brush 5103, such as a wire, the rotation of the brush 5103 can be stopped.

[0261] The display 5101 can display the remaining battery level, the amount of dust that has been sucked up, etc. The path traveled by the cleaning robot 5100 may be displayed on the display 5101. The display 5101 may also be a touch panel, and an operation button 5104 may be provided on the display 5101.

[0262] The cleaning robot 5100 can communicate with a portable electronic device 5140 such as a smartphone. Images captured by the camera 5102 can be displayed on the portable electronic device 5140. Therefore, the owner of the cleaning robot 5100 can know the state of the room even when he or she is away from home. In addition, the display on the display 5101 can be confirmed on the portable electronic device such as a smartphone.

[0263] The light-emitting device according to one embodiment of the present invention can be used for the display 5101 .

[0264] The robot 2100 shown in FIG. 8B includes a computing device 2110, an illumination sensor 2101, a microphone 2102, an upper camera 2103, a speaker 2104, a display 2105, a lower camera 2106, an obstacle sensor 2107, and a movement mechanism 2108.

[0265] The microphone 2102 has a function of detecting the user's speaking voice, environmental sounds, etc. The speaker 2104 has a function of emitting sound. The robot 2100 can communicate with the user using the microphone 2102 and the speaker 2104.

[0266] The display 2105 has a function of displaying various information. The robot 2100 can display information desired by the user on the display 2105. The display 2105 may be equipped with a touch panel. The display 2105 may also be a detachable information terminal, which can be installed in a fixed position on the robot 2100 to enable charging and data transfer.

[0267] The upper camera 2103 and the lower camera 2106 have a function of capturing images of the surroundings of the robot 2100. In addition, the obstacle sensor 2107 can detect the presence or absence of an obstacle in the moving direction when the robot 2100 moves forward using the moving mechanism 2108. The robot 2100 can recognize the surrounding environment and move safely using the upper camera 2103, the lower camera 2106, and the obstacle sensor 2107. The light-emitting device of one embodiment of the present invention can be used for the display 2105.

[0268] 8C is a diagram showing an example of a goggle-type display. The goggle-type display includes, for example, a housing 5000, a display unit 5001, a speaker 5003, an LED lamp 5004, a connection terminal 5006, a sensor 5007 (including a function for measuring force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared light), a microphone 5008, a display unit 5002, a support unit 5012, and earphones 5013.

[0269] The light-emitting device of one embodiment of the present invention can be used for the display portion 5001 and the second display portion 5002 .

[0270] 9 shows an example in which the light-emitting device described in Embodiment 1 is used in a desk lamp, which is a lighting device. The desk lamp shown in FIG. 9 includes a housing 2001 and a light source 2002, and the lighting device described in Embodiment 3 may be used as the light source 2002.

[0271] FIG. 10 shows an example in which the light-emitting device described in Embodiment 1 is used as an indoor lighting device 3001. The light-emitting device described in Embodiment 1 has high emission efficiency and can therefore be used as a lighting device with low power consumption. In addition, the light-emitting device described in Embodiment 1 can be made large in area and can therefore be used as a large-area lighting device. In addition, the light-emitting device described in Embodiment 1 is thin and can therefore be used as a thin lighting device.

[0272] The light-emitting device described in Embodiment 1 can also be mounted on a windshield or dashboard of an automobile. Figure 11 shows one mode in which the light-emitting device described in Embodiment 1 is used on a windshield or dashboard of an automobile. Display regions 5200 to 5203 are displays provided using the light-emitting device described in Embodiment 1.

[0273] The display region 5200 and the display region 5201 are display devices equipped with the light-emitting device described in Embodiment 1 and provided on the windshield of an automobile. The light-emitting device described in Embodiment 1 can be a so-called see-through display device, in which the opposite side can be seen through, by fabricating the anode and cathode using light-transmitting electrodes. A see-through display can be installed on the windshield of an automobile without obstructing the view. Note that when a transistor or the like is provided for driving the device, a light-transmitting transistor such as an organic transistor made of an organic semiconductor material or a transistor using an oxide semiconductor is preferably used.

[0274] The display area 5202 is a display device provided on a pillar and incorporating the light-emitting device described in Embodiment 1. By displaying an image from an imaging means provided on the vehicle body in the display area 5202, the view blocked by the pillar can be complemented. Similarly, the display area 5203 provided on the dashboard can complement the view blocked by the vehicle body by displaying an image from an imaging means provided on the outside of the vehicle, thereby compensating for blind spots and improving safety. By displaying an image to complement the invisible parts, safety can be confirmed more naturally and without discomfort.

[0275] The display area 5203 can also provide various information by displaying navigation information, a speedometer, a tachometer, air conditioning settings, etc. The display items and layout can be changed as needed to suit the user's preferences. Note that this information can also be provided in the display areas 5200 to 5202. The display areas 5200 to 5203 can also be used as lighting devices.

[0276] 12A and 12B show a foldable mobile information terminal 5150. The foldable mobile information terminal 5150 has a housing 5151, a display area 5152, and a bending portion 5153. FIG. 12A shows the mobile information terminal 5150 in an unfolded state. FIG. 12B shows the mobile information terminal in a folded state. Although the mobile information terminal 5150 has a large display area 5152, it is compact and highly portable when folded.

[0277] The display area 5152 can be folded in half by the bending portion 5153. The bending portion 5153 is composed of an expandable member and multiple support members, and when folding, the expandable member is stretched. The bending portion 5153 is folded with a curvature radius of 2 mm or more, preferably 3 mm or more.

[0278] Note that the display region 5152 may be a touch panel (input / output device) equipped with a touch sensor (input device). The light-emitting device of one embodiment of the present invention can be used for the display region 5152.

[0279] 13A to 13C show a foldable mobile information terminal 9310. Fig. 13A shows the mobile information terminal 9310 in an unfolded state. Fig. 13B shows the mobile information terminal 9310 in a state in the process of changing from one of the unfolded state and the folded state to the other. Fig. 13C shows the mobile information terminal 9310 in a folded state. The mobile information terminal 9310 has excellent portability in a folded state, and has excellent display visibility due to a seamless, wide display area in an unfolded state.

[0280] The display panel 9311 is supported by three housings 9315 connected by hinges 9313. Note that the display panel 9311 may be a touch panel (input / output device) equipped with a touch sensor (input device). The display panel 9311 can be reversibly transformed from an unfolded state of the mobile information terminal 9310 to a folded state by bending the two housings 9315 via the hinges 9313. The light-emitting device of one embodiment of the present invention can be used for the display panel 9311. [Example]

[0281] In this example, a light-emitting device 1 according to one embodiment of the present invention, which is described in the embodiment, and comparative light-emitting devices 1 to 3 will be described. The structural formulae of organic compounds used in this example are shown below.

[0282] [ka]

[0283] (Method for fabricating light-emitting device 1) First, a silver (Ag) film was formed on a glass substrate by sputtering to a thickness of 100 nm as a reflective electrode, and then an indium tin oxide (ITSO) film containing silicon oxide was formed on the glass substrate by sputtering to a thickness of 10 nm as a transparent electrode to form an anode 101. The electrode area was 4 mm 2 (2mm x 2mm).

[0284] Next, as a pretreatment for forming a light-emitting device on the substrate, the substrate surface was washed with water, baked at 200°C for 1 hour, and then subjected to UV ozone treatment for 370 seconds.

[0285] Then, 10 -4 The substrate was introduced into a vacuum deposition apparatus whose internal pressure had been reduced to about Pa, and after vacuum baking at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, the substrate was allowed to cool for about 30 minutes.

[0286] Next, the substrate on which the anode 101 was formed was fixed to a substrate holder installed in a vacuum deposition apparatus so that the surface on which the anode 101 was formed faced downward. N-(1,1'-biphenyl-2-yl)-N-(3,3'',5',5''-tetra-t-butyl-1,1':3',1''-terphenyl-5-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPoFBi-02) represented by the above structural formula (i) and an electron acceptor material (OCHD-001) were co-deposited on the anode 101 by a deposition method to a thickness of 10 nm in a weight ratio of 1:0.1 (=mmtBumTPoFBi-02:OCHD-001) to form a hole injection layer 111.

[0287] On the hole injection layer 111, mmtBumTPoFBi-02 was evaporated to a thickness of 130 nm to form a hole transport layer 112.

[0288] Next, 4-(dibenzothiophen-4-yl)-4'-phenyl-4''-(9-phenyl-9H-carbazol-2-yl)triphenylamine (abbreviation: PCBBiPDBt-02) represented by the above structural formula (ii) was vapor-deposited on the hole transport layer 112 to a thickness of 10 nm to form an electron blocking layer.

[0289] Thereafter, 2-(10-phenyl-9-anthracenyl)-benzo[b]naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA) represented by the above structural formula (iii) and 3,10-bis[N-(9-phenyl-9H-carbazol-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10PCA2Nbf(IV)-02) represented by the above structural formula (iv) were co-deposited to a thickness of 25 nm in a weight ratio of 1:0.015 (=Bnf(II)PhA:3,10PCA2Nbf(IV)-02) to form the light-emitting layer 113.

[0290] After that, 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)-1,1'-biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn) represented by the above structural formula (v) was deposited to a thickness of 10 nm to form a hole blocking layer, and then 2-{(3',5'-di-tert-butyl)-1,1'-biphenyl-3-yl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mmtBumBPTzn) represented by the above structural formula (vi) and 6-methyl-8-quinolinolato-lithium (abbreviation: Li-6mq) represented by the above structural formula (vii) were co-deposited to a thickness of 20 nm in a weight ratio of 1:1 (=mmtBumBPTzn:Li-6mq) to form an electron transport layer 114.

[0291] After forming the electron transport layer 114, lithium fluoride (LiF) was deposited to a thickness of 1 nm to form the electron injection layer 115. Finally, silver (Ag) and magnesium (Mg) were co-deposited in a volume ratio of 1:0.1 to a thickness of 15 nm to form the cathode 102, thereby producing the light-emitting device 1. The cathode 102 is a semi-transparent / semi-reflective electrode that has the functions of reflecting and transmitting light, and the light-emitting device of this example is a top-emission element that extracts light from the cathode 102. In addition, 1,3,5-tri(dibenzothiophen-4-yl)-benzene (abbreviation: DBT3P-II) represented by the above structural formula (viii) was deposited to a thickness of 70 nm on the cathode 102 to improve extraction efficiency.

[0292] (Method for producing comparative light-emitting device 1) Comparative light-emitting device 1 was fabricated in the same manner as light-emitting device 1, except that mmtBumTPoFBi-02 in light-emitting device 1 was replaced with N-(1,1'-biphenyl-4-yl)-9,9-dimethyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9H-fluoren-2-amine (abbreviation: PCBBiF) represented by the above structural formula (ix), and the thickness of the hole-transporting layer was changed to 115 nm.

[0293] (Method for producing comparative light-emitting device 2) Comparative light-emitting device 2 was fabricated in the same manner as light-emitting device 1, except that mmtBumBPTzn in the electron transport layer of light-emitting device 1 was replaced with 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn) represented by the above structural formula (vx), and Li-6mq was replaced with 8-quinolinolato-lithium (abbreviation: Liq) represented by the above structural formula (x).

[0294] (Method for producing comparative light-emitting device 3) Comparative light-emitting device 3 was fabricated in the same manner as light-emitting device 1, except that mmtBumTPoFBi-02 in light-emitting device 1 was replaced with PCBBiF, the thickness of the hole-transporting layer was set to 115 nm, mmtBumBPTzn in the electron-transporting layer was replaced with mPn-mDMePyPTzn, and Li-6mq was replaced with Liq.

[0295] The device structures of light-emitting device 1 and comparative light-emitting devices 1 to 3 are summarized in the table below.

[0296] [Table 1]

[0297] The refractive indices of mmtBumTPoFBi-02 and PCBBiF are shown in Figure 20, those of mmtBumBPTzn, mPn-mDMePyPTzn, Li-6mq, and Liq in Figure 21, and the refractive index at 456 nm is shown in the table below. Measurements were performed using a spectroscopic ellipsometer (M-2000U, manufactured by J.A. Woollam Japan). The measurement samples used were films of each layer formed on a quartz substrate by vacuum deposition to a thickness of approximately 50 nm. The figure also shows the refractive index for ordinary rays, n Ordinary, and the refractive index for extraordinary rays, n Extraordinary.

[0298] The figure shows that mmtBumTPoFBi-02 has an ordinary refractive index of 1.69 to 1.70 throughout the entire blue emission region (455 nm to 465 nm), falling within the range of 1.50 to 1.75. The ordinary refractive index at 633 nm is 1.64, falling within the range of 1.45 to 1.70, indicating that mmtBumTPoFBi-02 is a low-refractive index material. Furthermore, mmtBumBPTzn has an ordinary refractive index of 1.68 throughout the entire blue emission region (455 nm to 465 nm), falling within the range of 1.50 to 1.75. Furthermore, the ordinary refractive index at 633 nm is 1.64, falling within the range of 1.45 to 1.70, indicating that mmtBumBPTzn is a low-refractive index material. Furthermore, the ordinary refractive index of Li-6mq was 1.67 or less throughout the entire blue emission region (455 nm to 465 nm), falling within the range of 1.45 to 1.70.The ordinary refractive index at 633 nm was also 1.61, falling within the range of 1.40 to 1.65, indicating that Li-6mq is a material with a low refractive index.

[0299] This shows that the light-emitting device 1 is a light-emitting device in which the ordinary refractive index of both the hole transport layer 112 and the electron transport layer 114 is in the range of 1.50 or more and less than 1.75 throughout the entire blue light-emitting region (455 nm or more and 465 nm or less), and is in the range of 1.45 or more and less than 1.70 at 633 nm.

[0300] [Table 2]

[0301] The above light-emitting device and the comparative light-emitting device were sealed with a glass substrate in a nitrogen atmosphere glove box to prevent the light-emitting device from being exposed to the atmosphere (a UV-curable sealant was applied around the element, UV was irradiated only on the sealant without irradiating the light-emitting device, and heat-treated at 80°C under atmospheric pressure for 1 hour), and then the initial characteristics of these light-emitting devices were measured.

[0302] The luminance-current density characteristics of light-emitting device 1 and comparative light-emitting devices 1 to 3 are shown in Fig. 14, the luminance-voltage characteristics in Fig. 15, the current efficiency-luminance characteristics in Fig. 16, the current density-voltage characteristics in Fig. 17, the blue index-luminance characteristics in Fig. 18, and the emission spectra in Fig. 19. The luminance-current density characteristics of light-emitting device 1 and comparative light-emitting devices 1 to 3 are shown in Fig. 19. 2 The main characteristics in this range are shown in Table 3. The luminance, CIE chromaticity, and emission spectrum were measured using a spectroradiometer (SR-UL1R, manufactured by Topcon Corporation) at room temperature.

[0303] The blue index (BI) is the current efficiency (cd / A) divided by the y chromaticity and is an index that represents the luminous characteristics of blue light emission. The smaller the y chromaticity, the higher the color purity of blue light emission tends to be. Blue light emission with high color purity can express a wide range of blue colors even with a small luminance component. By using blue light emission with high color purity, the required luminance to express blue colors is reduced, resulting in reduced power consumption. Therefore, the BI, which takes into account the y chromaticity, an index of blue purity, is preferably used as a means of expressing the efficiency of blue light emission. Therefore, it can be said that light-emitting devices with a higher BI have better efficiency as blue light-emitting devices used in displays.

[0304] [Table 3]

[0305] 14 to 19 and Table 3, it was found that light-emitting device 1, in which a low-refractive index layer according to one embodiment of the present invention is used in both the hole-transporting region 120 and the electron-transporting region 121, is an EL device with good current efficiency and BI, while exhibiting almost the same emission spectrum as comparative light-emitting devices 1 and 2, in which a low-refractive index layer is provided only in either the hole-transporting region 120 or the electron-transporting region 121, and comparative light-emitting device 3, which does not have a low-refractive index region.

[0306] Furthermore, the luminance of light-emitting device 1 is 1000 cd / m 2 The blue index (BI) in the vicinity of 180 (cd / A / y) or more is very high, and the light-emitting device 1 can be said to have a particularly good BI. Therefore, one embodiment of the present invention is suitable for a light-emitting device used in a display. [Example]

[0307] In this example, a light-emitting device 10, which is the light-emitting device described in the embodiment, and comparative light-emitting devices 10 to 12 will be described. The structural formulas of the organic compounds used in this example are shown below.

[0308] [ka]

[0309] (Method of Making Light-Emitting Device 10) First, a silver (Ag) film was formed on a glass substrate by sputtering to a thickness of 100 nm as a reflective electrode, and then an indium tin oxide (ITSO) film containing silicon oxide was formed on the glass substrate by sputtering to a thickness of 10 nm as a transparent electrode to form an anode 101. The electrode area was 4 mm 2 (2mm x 2mm).

[0310] Next, as a pretreatment for forming a light-emitting device on the substrate, the substrate surface was washed with water, baked at 200°C for 1 hour, and then subjected to UV ozone treatment for 370 seconds.

[0311] Then, 10 -4 The substrate was introduced into a vacuum deposition apparatus whose internal pressure had been reduced to about Pa, and after vacuum baking at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, the substrate was allowed to cool for about 30 minutes.

[0312] Next, the substrate on which the anode 101 was formed was fixed to a substrate holder provided in a vacuum deposition apparatus so that the surface on which the anode 101 was formed faced downward. N,N-bis(4-cyclohexylphenyl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: dchPAF) represented by the above structural formula (xi) and an electron acceptor material (OCHD-001) were co-deposited on the anode 101 by a deposition method to a thickness of 10 nm at a weight ratio of 1:0.1 (=dchPAF:OCHD-001), thereby forming a hole injection layer 111.

[0313] On the hole injection layer 111, dchPAF was evaporated to a thickness of 125 nm to form a hole transport layer 112.

[0314] Next, N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP) represented by the above structural formula (xii) was vapor-deposited on the hole transport layer 112 to a thickness of 10 nm to form an electron blocking layer.

[0315] Thereafter, 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: αN-βNPAnth) represented by the above structural formula (xiii) and 3,10-bis[N-(9-phenyl-9H-carbazol-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10PCA2Nbf(IV)-02) represented by the above structural formula (iv) were co-deposited to a thickness of 20 nm in a weight ratio of 1:0.015 (=αN-βNPAnth:3,10PCA2Nbf(IV)-02) to form the light-emitting layer 113.

[0316] After that, 6-(1,1'-biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm) represented by the above structural formula (xiv) was evaporated to a thickness of 10 nm to form a hole blocking layer, and then 2-{(3',5'-di-tert-butyl)-1,1'-biphenyl-3-yl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mmtBumBPTzn) represented by the above structural formula (vi) and 6-methyl-8-quinolinolato-lithium (abbreviation: Li-6mq) represented by the above structural formula (vii) were co-evaporated to a thickness of 20 nm in a weight ratio of 1:1 (=mmtBumBPTzn:Li-6mq) to form an electron transport layer 114.

[0317] After forming the electron transport layer 114, lithium fluoride (LiF) was deposited to a thickness of 1 nm to form the electron injection layer 115. Finally, silver (Ag) and magnesium (Mg) were co-deposited in a volume ratio of 1:0.1 to form a 15 nm-thick cathode 102, thereby producing the light-emitting device 10. The cathode 102 is a semi-transparent / semi-reflective electrode that has the functions of reflecting and transmitting light, and the light-emitting device of this example is a top-emission element that extracts light from the cathode 102. In addition, 70 nm of 1,3,5-tri(dibenzothiophen-4-yl)-benzene (abbreviation: DBT3P-II) represented by the above structural formula (viii) was deposited on the cathode 102 by vapor deposition to improve extraction efficiency.

[0318] (Method for producing comparative light-emitting device 10) Comparative light-emitting device 10 was fabricated in the same manner as light-emitting device 10, except that dchPAF in light-emitting device 10 was replaced with N-(1,1'-biphenyl-4-yl)-9,9-dimethyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9H-fluoren-2-amine (abbreviation: PCBBiF) represented by the above structural formula (ix), and the thickness of the hole transport layer was set to 115 nm.

[0319] (Method for producing comparative light-emitting device 11) Comparative light-emitting device 11 was fabricated in the same manner as light-emitting device 10, except that mmtBumBPTzn in the electron-transporting layer of light-emitting device 10 was replaced with 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn) represented by the above structural formula (vx), Li-6mq was replaced with 8-quinolinolato-lithium (abbreviation: Liq) represented by the above structural formula (x), and the thickness of the hole-transporting layer was changed to 130 nm.

[0320] (Method for producing comparative light-emitting device 12) Comparative light-emitting device 12 was fabricated in the same manner as light-emitting device 10, except that dchPAF in the hole-transporting layer of light-emitting device 1 was replaced with PCBBiF, the thickness of which was 115 nm, mmtBumBPTzn in the electron-transporting layer was replaced with mPn-mDMePyPTzn, and Li-6mq was replaced with Liq.

[0321] The device structures of light-emitting device 10 and comparative light-emitting devices 10 to 12 are summarized in the table below.

[0322] [Table 4]

[0323] The refractive indices of dchPAF and PCBBiF are shown in Figure 31, those of mmtBumBPTzn, mPn-mDMePyPTzn, Li-6mq, and Liq in Figure 21, and the refractive index at 456 nm is shown in the table below. Measurements were performed using a spectroscopic ellipsometer (M-2000U, manufactured by J.A. Woollam Japan). The measurement samples used were films of each layer formed by vacuum deposition onto a quartz substrate to a thickness of approximately 50 nm. The figure also shows the refractive index for ordinary rays, n Ordinary, and the refractive index for extraordinary rays, n Extraordinary.

[0324] The figure shows that dchPAF has an ordinary refractive index of 1.71 throughout the entire blue emission region (455 nm to 465 nm), ranging from 1.50 to 1.75. The ordinary refractive index at 633 nm is 1.64, ranging from 1.45 to 1.70. This indicates that dchPAF is a low-refractive-index material. Furthermore, mmtBumBPTzn has an ordinary refractive index of 1.68 throughout the entire blue emission region (455 nm to 465 nm), ranging from 1.50 to 1.75. Furthermore, the ordinary refractive index at 633 nm is 1.64, ranging from 1.45 to 1.70. This indicates that mmtBumBPTzn is a low-refractive-index material. Furthermore, Li-6mq has an ordinary refractive index of 1.67 throughout the entire blue emission region (455 nm to 465 nm), ranging from 1.45 to 1.70. In addition, the refractive index for ordinary light at 633 nm was 1.61, which was in the range of 1.40 to 1.65, indicating that Li-6mq is a material with a low refractive index.

[0325] This indicates that the light-emitting device 10 is a light-emitting device according to one embodiment of the present invention, in which the ordinary refractive index of both the hole transport layer 112 and the electron transport layer 114 is in the range of 1.50 or more and less than 1.75 throughout the entire blue light-emitting region (455 nm or more and 465 nm or less), and in the range of 1.45 or more and less than 1.70 at 633 nm.

[0326] [Table 5]

[0327] The above light-emitting device and the comparative light-emitting device were sealed with a glass substrate in a nitrogen atmosphere glove box to prevent the light-emitting device from being exposed to the atmosphere (a UV-curable sealant was applied around the element, UV was irradiated only on the sealant without irradiating the light-emitting device, and heat-treated at 80°C under atmospheric pressure for 1 hour), and then the initial characteristics of these light-emitting devices were measured.

[0328] The luminance-current density characteristics of the light-emitting device 10 and the comparative light-emitting devices 10 to 12 are shown in Figure 25, the current efficiency-luminance characteristics in Figure 26, the luminance-voltage characteristics in Figure 27, the current-voltage characteristics in Figure 28, the blue index-luminance characteristics in Figure 29, and the emission spectra in Figure 30. The 1000 cd / m 2 The main characteristics in this range are shown in Table 6. The luminance, CIE chromaticity, and emission spectrum were measured using a spectroradiometer (SR-UL1R, manufactured by Topcon Corporation) at room temperature.

[0329] The blue index (BI) is the current efficiency (cd / A) divided by the y chromaticity and is an index that represents the luminous characteristics of blue light emission. The smaller the y chromaticity, the higher the color purity of blue light emission tends to be. Blue light emission with high color purity can express a wide range of blue colors even with a small luminance component. By using blue light emission with high color purity, the required luminance to express blue colors is reduced, resulting in reduced power consumption. Therefore, the BI, which takes into account the y chromaticity, an index of blue purity, is preferably used as a means of expressing the efficiency of blue light emission. Therefore, it can be said that light-emitting devices with a higher BI have better efficiency as blue light-emitting devices used in displays.

[0330] [Table 6]

[0331] 25 to 30 and Table 6, it can be seen that the light-emitting device 10, which uses a low-refractive index layer according to one embodiment of the present invention in both the hole transport region 120 and the electron transport region 121, is an EL device with good current efficiency and BI, while exhibiting an emission spectrum that is almost the same as that of the comparative light-emitting devices 10 and 11, which have a low-refractive index layer only in either the hole transport region 120 or the electron transport region 121, and the comparative light-emitting device 12, which does not have a low-refractive index region.

[0332] Furthermore, the light-emitting device 10 has a luminance of 1000 cd / m 2The blue index (BI) in the vicinity of 183 (cd / A / y) or more is very high, and the light-emitting device 10 can be said to have a particularly good BI. Therefore, one embodiment of the present invention is suitable for a light-emitting device used in a display.

[0333] ≪Reference synthesis example 1≫ This synthesis example describes a method for synthesizing N-(1,1'-biphenyl-2-yl)-N-(3,3'',5',5''-tetra-t-butyl-1,1':3',1''-terphenyl-5-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPoFBi-02) used in Example 1. The structure of mmtBumTPoFBi-02 is shown below.

[0334] [ka]

[0335] <Step 1: Synthesis of 3-bromo-3',5,5'-tri-tertbutylbiphenyl> A three-neck flask was charged with 37.2 g (128 mmol) of 1,3-dibromo-5-tert-butylbenzene, 20.0 g (85 mmol) of 3,5-ditert-butylphenylboronic acid, 35.0 g (255 mmol) of potassium carbonate, 570 mL of toluene, 170 mL of ethanol, and 130 mL of tap water. After degassing under reduced pressure, the flask was purged with nitrogen, and 382 mg (1.7 mmol) of palladium acetate and 901 mg (3.4 mmol) of triphenylphosphine were added. The mixture was heated at 40 °C for approximately 5 hours. The temperature was then returned to room temperature, and the organic and aqueous layers were separated. Magnesium sulfate was added to the organic layer to remove water and concentrate it. The resulting solution was purified by silica gel column chromatography to obtain 21.5 g of the desired colorless oil in 63% yield. The synthetic scheme for Step 1 is shown below.

[0336] [ka]

[0337] <Step 2: Synthesis of 2-(3',5,5'-tri-tert-butyl[1,1'-biphenyl]-3-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane> A three-neck flask was charged with 15.0 g (38 mmol) of 3-bromo-3',5,5'-tri-tertbutylbiphenyl obtained in Step 1, 10.5 g (41 mmol) of 4,4,4',4',5,5,5',5-octamethyl-2,2'-bi-1,3,2-dioxaborolane, 11.0 g (113 mmol) of potassium acetate, and 125 mL of N,N-dimethylformamide. After degassing under reduced pressure, the flask was purged with nitrogen, and 1.5 g (1.9 mmol) of [1,1'-bis(diphenylphosphino)ferrocene]dichloropalladium(II) was added. The mixture was heated at 100 °C for approximately 3 hours. The organic and aqueous layers were then separated and extracted with ethyl acetate. Magnesium sulfate was added to the extracted solution to remove water and concentrate it. A toluene solution of the resulting mixture was purified by silica gel column chromatography, and the resulting solution was concentrated to obtain a concentrated toluene solution. Ethanol was added to this toluene solution, and the mixture was concentrated under reduced pressure to obtain an ethanol suspension. The precipitate was filtered at approximately 20°C, and the resulting solid was dried under reduced pressure at approximately 80°C to obtain 13.6 g of the target white solid in an 81% yield. The synthetic scheme for Step 2 is shown below.

[0338] [ka]

[0339] <Step 3: Synthesis of 3-bromo-3'',5,5',5''-tetratertbutyl-1,1':3',1''-terphenyl> A three-neck flask was charged with 5.0 g (11.1 mmol) of 2-(3',5,5'-tritertbutyl[1,1'-biphenyl]-3-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane, 4.8 g (16.7 mmol) of 1,3-dibromo-5-tertbutylbenzene, 4.6 g (33.3 mmol) of potassium carbonate, 56 mL of toluene, 22 mL of ethanol, and 17 mL of tap water. After degassing under reduced pressure, the flask was purged with nitrogen, and 50 mg (0.22 mmol) of palladium acetate and 116 mg (0.44 mmol) of triphenylphosphine were added. The mixture was heated at 80 °C for approximately 10 hours. The temperature was then returned to room temperature, and the organic and aqueous layers were separated. Magnesium sulfate was added to the solution to remove water and concentrate it. The resulting hexane solution was purified by silica gel column chromatography to obtain 3.0 g of the desired white solid in a 51.0% yield. The synthetic scheme of Step 3, 3-bromo-3'',5,5',5''-tetratertbutyl-1,1':3',1''-terphenyl, is shown below.

[0340] [ka]

[0341] <Step 4: Synthesis of mmtBumTPoFBi-02> A three-neck flask was charged with 5.8 g (10.9 mmol) of 3-bromo-3'',5,5',5''-tetratertbutyl-1,1':3',1''-terphenyl obtained in Step 3, 3.9 g (10.9 mmol) of N-(1,1'-biphenyl-4-yl)-N-phenyl-9,9-dimethyl-9H-fluoren-2-amine, 3.1 g (32.7 mmol) of sodium tert-butoxide, and 55 mL of toluene. The flask was degassed under reduced pressure, and then the atmosphere in the flask was replaced with nitrogen. 64 mg (0.11 mmol) of bis(dibenzylideneacetone)palladium(0) and 132 mg (0.65 mmol) of tri-tert-butylphosphine were added and heated at 80°C for approximately 2 hours. The flask was then returned to approximately 60°C, approximately 1 mL of water was added, and the precipitated solid was collected by filtration and washed with toluene. The filtrate was concentrated, and the resulting toluene solution was purified by silica gel column chromatography. The resulting solution was concentrated to obtain a concentrated toluene solution. Ethanol was added to this toluene solution, and the mixture was concentrated under reduced pressure to obtain an ethanol suspension. The precipitate was filtered at approximately 20°C, and the resulting solid was dried under reduced pressure at approximately 80°C to obtain 8.1 g of the target white solid in a 91% yield. The synthetic scheme for mmtBumTPoFBi-02 is shown below.

[0342] [ka]

[0343] The white solid obtained above was analyzed by nuclear magnetic resonance spectroscopy ( 1 The results of the analysis by H-NMR are shown below, which demonstrate that mmtBumTPoFBi-02 was successfully synthesized.

[0344] 1H-NMR.δ(CDCl3):7.56(d,1H,J=7.4Hz),7.50(dd,1H,J=1.7Hz),7.33-7.46(m,11H),7.27-7.29(m,2H),7.22(dd,1H,J=2.3Hz),7 .15(d,1H,J=6.9Hz),6.98-7.07(m,7H),6.93(s,1H),6.84(d,1H,J=6.3Hz),1.38(s,9H),1.37(s,18H),1.31(s,6H),1.20(s,9H).

[0345] Figure 22 shows the results of measuring the refractive index of mmtBumTPoFBi-02 using a spectroscopic ellipsometer (M-2000U manufactured by J.A. Woollam Japan). For the measurements, a film of approximately 50 nm thickness was formed on a quartz substrate using vacuum deposition of each layer material. The figure also shows the refractive index for ordinary rays, n Ordinary, and the refractive index for extraordinary rays, n Extraordinary.

[0346] From this figure, it can be seen that mmtBumTPoFBi-02 has an ordinary refractive index of 1.69 to 1.70 throughout the entire blue emission region (455 nm or more and 465 nm or less), in the range of 1.50 to 1.75, and that the ordinary refractive index at 633 nm is 1.64, in the range of 1.45 to 1.70, making it a material with a low refractive index.

[0347] ≪Reference synthesis example 2≫ This synthesis example describes a method for synthesizing 2-{(3',5'-di-tert-butyl)-1,1'-biphenyl-3-yl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mmtBumBPTzn) used in Example 1. The structure of mmtBumBPTzn is shown below.

[0348] [ka]

[0349] <Step 1: Synthesis of 3-bromo-3',5'-di-tert-butylbiphenyl> A three-neck flask was charged with 1.0 g (4.3 mmol) of 3,5-di-t-butylphenylboronic acid, 1.5 g (5.2 mmol) of 1-bromo-3-iodobenzene, 4.5 mL of 2 mol / L aqueous potassium carbonate, 20 mL of toluene, and 3 mL of ethanol. The mixture was degassed by stirring under reduced pressure. 52 mg (0.17 mmol) of tris(2-methylphenyl)phosphine and 10 mg (0.043 mmol) of palladium(II) acetate were added and reacted at 80 °C for 14 hours under a nitrogen atmosphere. After the reaction was complete, the mixture was extracted with toluene, and the resulting organic layer was dried over magnesium sulfate. The mixture was gravity filtered, and the filtrate was purified by silica gel column chromatography (eluent: hexane) to obtain 1.0 g of the desired white solid (yield: 68%). The synthesis scheme for Step 1 is shown below.

[0350] [ka]

[0351] Step 2: Synthesis of 2-(3',5'-di-tert-butylbiphenyl-3-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane A three-neck flask was charged with 1.0 g (2.9 mmol) of 3-bromo-3',5'-di-tert-butylbiphenyl, 0.96 g (3.8 mmol) of bis(pinacolato)diboron, 0.94 g (9.6 mmol) of potassium acetate, and 30 mL of 1,4-dioxane. The mixture was degassed by stirring under reduced pressure. To this mixture was added 0.12 g (0.30 mmol) of 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl and 0.12 g (0.15 mmol) of [1,1'-bis(diphenylphosphino)ferrocene]palladium(II) dichloride dichloromethane adduct. The mixture was then reacted under a nitrogen atmosphere at 110°C for 24 hours. After the reaction was complete, the mixture was extracted with toluene, and the resulting organic layer was dried over magnesium sulfate. The mixture was then gravity filtered. The obtained filtrate was purified by silica gel column chromatography (developing solvent: toluene) to obtain 0.89 g of the target yellow oil (yield: 78%). The synthesis scheme of Step 2 is shown below.

[0352] [ka]

[0353] <Step 3: Synthesis of mmtBumBPTzn> A three-neck flask was charged with 1.5 g (5.6 mmol) of 4,6-diphenyl-2-chloro-1,3,5-triazine, 2.4 g (6.2 mmol) of 2-(3',5'-di-tert-butylbiphenyl-3-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane, 2.4 g (11 mmol) of tripotassium phosphate, 10 mL of water, 28 mL of toluene, and 10 mL of 1,4-dioxane. The mixture was degassed by stirring under reduced pressure. To this mixture was added 13 mg (0.056 mmol) of palladium(II) acetate and 34 mg (0.11 mmol) of tris(2-methylphenyl)phosphine. The mixture was heated under reflux for 14 hours under a nitrogen atmosphere. After completion of the reaction, the mixture was extracted with ethyl acetate, and the resulting organic layer was dehydrated with magnesium sulfate. The mixture was gravity filtered, and the resulting filtrate was purified by silica gel column chromatography (the developing solvent was changed from chloroform:hexane = 1:5 to 1:3), and then recrystallized from hexane to obtain 2.0 g of the desired white solid (yield: 51%). The synthesis scheme for Step 3 is shown below.

[0354] [ka]

[0355] 2.0 g of the obtained white solid was purified by train sublimation by heating the solid under conditions of argon gas flow, pressure 3.4 Pa, and 220°C. After sublimation purification, 1.8 g of the target white solid was obtained with a recovery rate of 80%.

[0356] The white solid obtained in step 3 was analyzed by nuclear magnetic resonance spectroscopy ( 1 The results of the analysis by H-NMR are shown below. From these results, it was found that mmtBumBPTzn was obtained in this synthesis example.

[0357] H 1 NMR (CDCl3, 300MHz): δ = 1.44 (s, 18H), 7.51-7.68 (m, 10H), 7.83 (d, 1H), 8.73-8.81 (m, 5H), 9.01 (s, 1H).

[0358] Figure 23 shows the results of measuring the refractive index of mmtBumBPTzn using a spectroscopic ellipsometer (M-2000U manufactured by J.A. Woollam Japan). For the measurements, a film of approximately 50 nm thickness was used, in which the materials for each layer were deposited on a quartz substrate by vacuum deposition. The figure also shows the refractive index for ordinary rays, n Ordinary, and the refractive index for extraordinary rays, n Extraordinary.

[0359] From this figure, it can be seen that the ordinary refractive index of mmtBumBPTzn is 1.68 throughout the entire blue emission region (455 nm to 465 nm), falling within the range of 1.50 to 1.75. The ordinary refractive index at 633 nm is also 1.64, falling within the range of 1.45 to 1.70, indicating that mmtBumBPTzn is a material with a low refractive index.

[0360] ≪Reference synthesis example 3≫ This example describes a method for synthesizing 6-methyl-8-quinolinolato-lithium (abbreviation: Li-6mq) used in Example 1. The structural formula of Li-6mq is shown below.

[0361] [ka]

[0362] 2.0 g (12.6 mmol) of 8-hydroxy-6-methylquinoline and 130 mL of anhydrous tetrahydrofuran (THF) were placed in a three-neck flask and stirred. 10.1 mL (10.1 mmol) of a 1 M THF solution of lithium tert-butoxide (tBuOLi) was added to this solution and stirred at room temperature for 47 hours. The reaction solution was concentrated to give a yellow solid. Acetonitrile was added to this solid, and the mixture was subjected to ultrasonic irradiation and filtration to give a pale yellow solid. This washing procedure was repeated twice. 1.6 g (95% yield) of a pale yellow solid of Li-6mq was obtained as the filtrate. The synthesis scheme is shown below.

[0363] [ka]

[0364] Next, the absorption and emission spectra of Li-6mq in anhydrous acetone solution were measured. The absorption spectrum was measured using a UV-visible spectrophotometer (V550, manufactured by JASCO Corporation) and the spectrum measured using only anhydrous acetone in a quartz cell was subtracted from the absorption spectrum. The emission spectrum was measured using a fluorometer (FP-8600, manufactured by JASCO Corporation).

[0365] As a result, the dehydrated acetone solution of Li-6mq showed an absorption peak at 390 nm and an emission wavelength peak at 540 nm (excitation wavelength 385 nm).

[0366] Figure 24 shows the results of measuring the refractive index of Li-6mq using a spectroscopic ellipsometer (M-2000U manufactured by J.A. Woollam Japan). For the measurements, a film of approximately 50 nm thickness was formed on a quartz substrate using vacuum deposition of the materials for each layer. The figure also shows the refractive index for ordinary rays, n Ordinary, and the refractive index for extraordinary rays, n Extraordinary.

[0367] This figure shows that Li-6mq is a material with a low refractive index. [Explanation of symbols]

[0368] 101: anode, 102: cathode, 103: EL layer, 111: hole injection layer, 112: hole transport layer, 113: light emitting layer, 114: 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: hole transport region, 121: electron transport region, 400: substrate, 401: anode, 403: EL layer, 404: cathode, 405: sealing material, 406: sealing material, 407: sealing substrate, 412: pad, 420: IC chip, 601: drive circuit section (solar 602: pixel section, 603: driver circuit section (gate line driver circuit), 604: sealing substrate, 605: seal material, 607: space, 608: wiring, 609: FPC (flexible printed circuit), 610: element substrate, 611: switching FET, 612: current control FET, 613: anode, 614: insulator, 616: EL layer, 617: cathode, 618: light emitting device, 951: substrate, 952: electrode, 953: insulating layer, 954: partition layer, 955: EL layer, 956: electrode, 1001 Substrate, 1002, base insulating film, 1003, gate insulating film, 1006, gate electrode, 1007, gate electrode, 1008, gate electrode, 1020, first interlayer insulating film, 1021, second interlayer insulating film, 1022, electrode, 1024W, anode, 1024R, anode, 1024G, anode, 1024B, anode, 1025, partition wall, 1028, EL layer, 1029, cathode, 1031, sealing substrate, 1032, sealing material, 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, 1042Peripheral part, 2001: housing, 2002: light source, 2100: robot, 2110: computing device, 2101: illuminance sensor, 2102: microphone, 2103: upper camera, 2104: speaker, 2105: display, 2106: lower camera, 2107: obstacle sensor, 2108: moving mechanism, 3001: lighting device, 5000: housing, 5001: display part, 5002: second display part, 5003: speaker, 5004: LED lamp, 5006: connection terminal, 5007: sensor, 5008: microphone, 5012: support part, 5013: earphone, 5100: cleaning robot, 5101: display, 5102: camera, 5103: brush, 5104: operation button, 5150: mobile information terminal, 5151: Housing, 5152: Display area, 5153: Bending part, 5120: Dust, 5200: Display area, 5201: Display area, 5202: Display area, 5203: Display area, 7101: Housing, 7103: Display unit, 7105: Stand, 7107: Display unit, 7109: Operation keys, 7110: Remote control unit, 7201: Main unit, 7202: Housing, 7203 : Display unit, 7204: Keyboard, 7205: External connection port, 7206: Pointing device, 7210: Display unit, 7401: Housing, 7402: Display unit, 7403: Operation buttons, 7404: External connection port, 7405: Speaker, 7406: Microphone, 9310: Portable information terminal, 9311: Display panel, 9313: Hinge, 9315: Housing

Claims

1. an anode; A cathode; a first layer, a second layer, and a third layer located between the anode and the cathode; the first layer is located between the anode and the second layer; the third layer is located between the second layer and the cathode; the first layer includes an organic compound having a hole transporting property and a substance having an acceptor property, the third layer contains an organic compound having an electron transport property, the organic compound having hole transport properties is a monoamine compound, and a ratio of carbon atoms forming bonds via sp3 hybrid orbitals to the total number of carbon atoms in the monoamine compound is 23% or more and 55% or less; The organic compound having hole transport properties and the organic compound having electron transport properties each have an ordinary refractive index of 1.5 or more and 1.75 or less for light with a wavelength of 455 nm or more and 465 nm or less.

2. an anode; A cathode; a first layer, a second layer, and a third layer located between the anode and the cathode; the first layer is located between the anode and the second layer; the third layer is located between the second layer and the cathode; the first layer contains an organic compound having a hole transporting property and a substance having a halogen group or a cyano group, the third layer contains an organic compound having an electron transport property, the organic compound having hole transport properties is a monoamine compound, and a ratio of carbon atoms forming bonds via sp3 hybrid orbitals to the total number of carbon atoms in the monoamine compound is 23% or more and 55% or less; The organic compound having hole transport properties and the organic compound having electron transport properties each have an ordinary refractive index of 1.5 or more and 1.75 or less for light with a wavelength of 455 nm or more and 465 nm or less.

3. an anode; A cathode; a first layer, a second layer, and a third layer located between the anode and the cathode; the first layer is located between the anode and the second layer; the third layer is located between the second layer and the cathode; the first layer includes an organic compound having a hole transporting property and a substance having an acceptor property, the third layer contains an organic compound having an electron transport property, the organic compound having electron transport properties has at least one nitrogen-containing six-membered heteroaromatic ring, two benzene rings, one or more aromatic hydrocarbon rings having 6 to 14 carbon atoms, and a hydrocarbon group forming bonds via a plurality of sp3 hybridized orbitals, and the total number of carbon atoms forming bonds via the sp3 hybridized orbitals is 10% or more and 60% or less of the total number of carbon atoms in a molecule of the organic compound having electron transport properties, The organic compound having hole transport properties and the organic compound having electron transport properties each have an ordinary refractive index of 1.5 or more and 1.75 or less for light with a wavelength of 455 nm or more and 465 nm or less.

4. an anode; A cathode; a first layer, a second layer, and a third layer located between the anode and the cathode; the first layer is located between the anode and the second layer; the third layer is located between the second layer and the cathode; the first layer contains an organic compound having a hole transporting property and a substance having a halogen group or a cyano group, the third layer contains an organic compound having an electron transport property, the organic compound having electron transport properties has at least one nitrogen-containing six-membered heteroaromatic ring, two benzene rings, one or more aromatic hydrocarbon rings having 6 to 14 carbon atoms, and a hydrocarbon group forming bonds via a plurality of sp3 hybridized orbitals, and the total number of carbon atoms forming bonds via the sp3 hybridized orbitals is 10% or more and 60% or less of the total number of carbon atoms in a molecule of the organic compound having electron transport properties, The organic compound having hole transport properties and the organic compound having electron transport properties each have an ordinary refractive index of 1.5 or more and 1.75 or less for light with a wavelength of 455 nm or more and 465 nm or less.

5. an anode; A cathode; a first layer, a second layer, and a third layer located between the anode and the cathode; the first layer is located between the anode and the second layer; the third layer is located between the second layer and the cathode; the first layer includes an organic compound having a hole transporting property and a substance having an acceptor property, the third layer contains an organic compound having an electron transport property, the organic compound having hole transport properties is a monoamine compound, and a ratio of carbon atoms forming bonds via sp3 hybrid orbitals to the total number of carbon atoms in the monoamine compound is 23% or more and 55% or less; the organic compound having electron transport properties has at least one nitrogen-containing six-membered heteroaromatic ring, two benzene rings, one or more aromatic hydrocarbon rings having 6 to 14 carbon atoms, and a hydrocarbon group forming bonds via a plurality of sp3 hybridized orbitals, and the total number of carbon atoms forming bonds via the sp3 hybridized orbitals is 10% or more and 60% or less of the total number of carbon atoms in a molecule of the organic compound having electron transport properties, The organic compound having hole transport properties and the organic compound having electron transport properties each have an ordinary refractive index of 1.5 or more and 1.75 or less for light with a wavelength of 455 nm or more and 465 nm or less.

6. an anode; A cathode; a first layer, a second layer, and a third layer located between the anode and the cathode; the first layer is located between the anode and the second layer; the third layer is located between the second layer and the cathode; the first layer contains an organic compound having a hole transporting property and a substance having a halogen group or a cyano group, the third layer contains an organic compound having an electron transport property, the organic compound having hole transport properties is a monoamine compound, and a ratio of carbon atoms forming bonds via sp3 hybrid orbitals to the total number of carbon atoms in the monoamine compound is 23% or more and 55% or less; the organic compound having electron transport properties has at least one nitrogen-containing six-membered heteroaromatic ring, two benzene rings, one or more aromatic hydrocarbon rings having 6 to 14 carbon atoms, and a hydrocarbon group forming bonds via a plurality of sp3 hybridized orbitals, and the total number of carbon atoms forming bonds via the sp3 hybridized orbitals is 10% or more and 60% or less of the total number of carbon atoms in a molecule of the organic compound having electron transport properties, The organic compound having hole transport properties and the organic compound having electron transport properties each have an ordinary refractive index of 1.5 or more and 1.75 or less for light with a wavelength of 455 nm or more and 465 nm or less.

7. an anode; A cathode; a first layer, a second layer, and a third layer located between the anode and the cathode; the first layer is located between the anode and the second layer; the third layer is located between the second layer and the cathode; the first layer includes an organic compound having a hole transporting property and a substance having an acceptor property, the third layer contains an organic compound having an electron transport property, the organic compound having hole transport properties is a monoamine compound, and a ratio of carbon atoms forming bonds via sp3 hybrid orbitals to the total number of carbon atoms in the monoamine compound is 23% or more and 55% or less; The light-emitting device, wherein the organic compound having hole transport properties and the organic compound having electron transport properties each have a refractive index of 1.45 or more and 1.70 or less with respect to light having a wavelength of 633 nm.

8. an anode; A cathode; a first layer, a second layer, and a third layer located between the anode and the cathode; the first layer is located between the anode and the second layer; the third layer is located between the second layer and the cathode; the first layer contains an organic compound having a hole transporting property and a substance having a halogen group or a cyano group, the third layer contains an organic compound having an electron transport property, the organic compound having hole transport properties is a monoamine compound, and a ratio of carbon atoms forming bonds via sp3 hybrid orbitals to the total number of carbon atoms in the monoamine compound is 23% or more and 55% or less; The light-emitting device, wherein the organic compound having hole transport properties and the organic compound having electron transport properties each have a refractive index of 1.45 or more and 1.70 or less with respect to light having a wavelength of 633 nm.

9. an anode; A cathode; a first layer, a second layer, and a third layer located between the anode and the cathode; the first layer is located between the anode and the second layer; the third layer is located between the second layer and the cathode; the first layer includes an organic compound having a hole transporting property and a substance having an acceptor property, the third layer contains an organic compound having an electron transport property, the organic compound having electron transport properties has at least one nitrogen-containing six-membered heteroaromatic ring, two benzene rings, one or more aromatic hydrocarbon rings having 6 to 14 carbon atoms, and a hydrocarbon group forming bonds via a plurality of sp3 hybridized orbitals, and the total number of carbon atoms forming bonds via the sp3 hybridized orbitals is 10% or more and 60% or less of the total number of carbon atoms in a molecule of the organic compound having electron transport properties, The light-emitting device, wherein the organic compound having hole transport properties and the organic compound having electron transport properties each have a refractive index of 1.45 or more and 1.70 or less with respect to light having a wavelength of 633 nm.

10. an anode; A cathode; a first layer, a second layer, and a third layer located between the anode and the cathode; the first layer is located between the anode and the second layer; the third layer is located between the second layer and the cathode; the first layer contains an organic compound having a hole transporting property and a substance having a halogen group or a cyano group, the third layer contains an organic compound having an electron transport property, the organic compound having electron transport properties has at least one nitrogen-containing six-membered heteroaromatic ring, two benzene rings, one or more aromatic hydrocarbon rings having 6 to 14 carbon atoms, and a hydrocarbon group forming bonds via a plurality of sp3 hybridized orbitals, and the total number of carbon atoms forming bonds via the sp3 hybridized orbitals is 10% or more and 60% or less of the total number of carbon atoms in a molecule of the organic compound having electron transport properties, The light-emitting device, wherein the organic compound having hole transport properties and the organic compound having electron transport properties each have a refractive index of 1.45 or more and 1.70 or less with respect to light having a wavelength of 633 nm.

11. an anode; A cathode; a first layer, a second layer, and a third layer located between the anode and the cathode; the first layer is located between the anode and the second layer; the third layer is located between the second layer and the cathode; the first layer includes an organic compound having a hole transporting property and a substance having an acceptor property, the third layer contains an organic compound having an electron transport property, the organic compound having hole transport properties is a monoamine compound, and a ratio of carbon atoms forming bonds via sp3 hybrid orbitals to the total number of carbon atoms in the monoamine compound is 23% or more and 55% or less; the organic compound having electron transport properties has at least one nitrogen-containing six-membered heteroaromatic ring, two benzene rings, one or more aromatic hydrocarbon rings having 6 to 14 carbon atoms, and a hydrocarbon group forming bonds via a plurality of sp3 hybridized orbitals, and the total number of carbon atoms forming bonds via the sp3 hybridized orbitals is 10% or more and 60% or less of the total number of carbon atoms in a molecule of the organic compound having electron transport properties, The light-emitting device, wherein the organic compound having hole transport properties and the organic compound having electron transport properties each have a refractive index of 1.45 or more and 1.70 or less with respect to light having a wavelength of 633 nm.

12. an anode; A cathode; a first layer, a second layer, and a third layer located between the anode and the cathode; the first layer is located between the anode and the second layer; the third layer is located between the second layer and the cathode; the first layer contains an organic compound having a hole transporting property and a substance having a halogen group or a cyano group, the third layer contains an organic compound having an electron transport property, the organic compound having hole transport properties is a monoamine compound, and a ratio of carbon atoms forming bonds via sp3 hybrid orbitals to the total number of carbon atoms in the monoamine compound is 23% or more and 55% or less; the organic compound having electron transport properties has at least one nitrogen-containing six-membered heteroaromatic ring, two benzene rings, one or more aromatic hydrocarbon rings having 6 to 14 carbon atoms, and a hydrocarbon group forming bonds via a plurality of sp3 hybridized orbitals, and the total number of carbon atoms forming bonds via the sp3 hybridized orbitals is 10% or more and 60% or less of the total number of carbon atoms in a molecule of the organic compound having electron transport properties, The light-emitting device, wherein the organic compound having hole transport properties and the organic compound having electron transport properties each have a refractive index of 1.45 or more and 1.70 or less with respect to light having a wavelength of 633 nm.

13. In any one of claims 1 to 12, The light-emitting device wherein the first layer is a hole-injection layer.

14. In any one of claims 1 to 13, The light-emitting device wherein the third layer is an electron transport layer and / or an electron injection layer.

15. In any one of claims 1 to 14, A light-emitting device in which one or both of the anode and the cathode have a function of reflecting all or part of light from a light-emitting layer.

16. In any one of claims 1 to 15, A light-emitting device wherein one or both of the anode and the cathode comprise a metal.

17. In any one of claims 1 to 16, The light-emitting device, wherein the second layer is a light-emitting layer.

18. A light emitting device according to any one of claims 1 to 17; At least one of a sensor, an operation button, a speaker, and a microphone; An electronic device having:

19. A light emitting device according to any one of claims 1 to 17; at least one of a transistor and a substrate; A light emitting device having the

20. A light-emitting device according to any one of claims 1 to 17, and a housing; A lighting device having:

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