Light emitting device, light emitting apparatus, light emitting module, electronic apparatus, and lighting device

Abstract

To provide a light emitting device having high luminous efficiency and a low drive voltage.SOLUTION: A light emitting device includes: a first electrode; a first layer over the first electrode; a second layer over the first layer; a light emitting layer over the second layer; and a second electrode over the light emitting layer. The first layer includes a first organic compound and the second layer includes a second organic compound. A ratio of the number of carbon atoms of the first organic compound forming a bond by an sp3 hybrid orbit to the total number of carbon atoms is 23% or more and 55% or less. The second organic compound contains fluorine.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One aspect of the present invention relates to an optical device such as a light-emitting device, a light-receiving device, and a light-emitting and receiving device. One aspect of the present invention relates to an apparatus such as a light-emitting device, a light-receiving device, and a light-emitting and receiving device. One aspect of the present invention relates to a module such as a light-emitting module, a light-receiving module, a light-emitting and receiving module, a display module, and a lighting module. One aspect of the present invention relates to an electronic device and a lighting device.

[0002] One embodiment of the present invention is not limited to the above technical field, and examples of the technical field of one embodiment of the present invention include a semiconductor device, a display device, a light-emitting device, a power storage device, a memory device, an electronic device, a lighting device, an input device (for example, a touch sensor), an input / output device (for example, a touch panel), a driving method thereof, or a manufacturing method thereof. [Background technology]

[0003] Research and development of light-emitting devices (also called organic EL devices or organic EL elements) that utilize the organic electroluminescence (EL) phenomenon is actively underway. The basic structure of an organic EL device is a layer containing a light-emitting organic compound (hereinafter referred to as the light-emitting layer) sandwiched between a pair of electrodes. By applying a voltage to this organic EL device, light can be emitted from the light-emitting organic compound.

[0004] Organic EL devices have features such as the ease of being made thin and lightweight, the ability to respond quickly to input signals, and the ability to be driven using a DC constant voltage power supply, making them suitable for use in display devices.

[0005] Furthermore, organic EL devices can be formed into a film, allowing for planar light emission. This makes it easy to form a large-area light-emitting device. This is a feature that is difficult to obtain with point light sources such as LEDs (light-emitting diodes) and linear light sources such as fluorescent lamps, making organic EL devices highly useful as planar light sources that can be applied to lighting devices and the like.

[0006] There is a demand for further improvement in the light extraction efficiency of organic EL devices. Attenuation of light due to reflection caused by differences in the refractive index of adjacent layers is one of the factors that reduces the light extraction efficiency. In organic EL devices, the light extraction efficiency can be improved by using a material with a low refractive index. For example, Non-Patent Document 1 discloses an organic EL device having a layer with a low refractive index.

[0007] On the other hand, it is difficult for materials used in organic EL devices to have both a low refractive index and high reliability or high heat resistance. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] US Patent Application Publication No. 2020 / 0176692 Summary of the Invention [Problem to be solved by the invention]

[0009] An object of one embodiment of the present invention is to provide a light-emitting device or a light-receiving / light-emitting device with high emission efficiency.An object of one embodiment of the present invention is to provide a light-emitting device or a light-receiving / light-emitting device with high light extraction efficiency.An object of one embodiment of the present invention is to provide a light-emitting device, a light-receiving device, or a light-receiving / light-emitting device with low driving voltage.An object of one embodiment of the present invention is to provide a light-emitting device, a light-receiving device, or a light-receiving / light-emitting device with high heat resistance.An object of one embodiment of the present invention is to provide a light-emitting device, a light-receiving device, or a light-receiving / light-emitting device with a long lifetime.An object of one embodiment of the present invention is to provide a light-emitting device, a light-receiving device, or a light-receiving / light-emitting device with low power consumption.

[0010] Note that the description of these problems does not preclude the existence of other problems. One embodiment of the present invention does not necessarily have to solve all of these problems. Problems other than these can be extracted from the description in the specification, drawings, and claims. [Means for solving the problem]

[0011] One embodiment of the present invention is a light-emitting device comprising a first electrode, a first layer on the first electrode, a second layer on the first layer, a light-emitting layer on the second layer, and a second electrode on the light-emitting layer, wherein the first layer comprises a first organic compound, the second layer comprises a second organic compound, and the ratio of the number of carbon atoms forming bonds with sp3 hybrid orbitals to the total number of carbon atoms in the first organic compound is 23% to 55%, and the second organic compound contains fluorine. The refractive index of the layer made of the first organic compound for light with a wavelength of 633 nm is preferably 1.45 to 1.70.

[0012] Alternatively, one embodiment of the present invention is a light-emitting device including a first electrode, a first layer over the first electrode, a second layer over the first layer, a light-emitting layer over the second layer, and a second electrode over the light-emitting layer, in which the first layer includes a first organic compound and the second layer includes a second organic compound, the first organic compound having a glass transition temperature of 90°C or higher, the layer made of the first organic compound having a refractive index of 1.45 or higher and 1.70 or lower for light with a wavelength of 633 nm, and the second organic compound containing fluorine.

[0013] The first organic compound is preferably an amine compound, more preferably a monoamine compound.

[0014] Alternatively, one embodiment of the present invention is a light-emitting device including a first electrode, a first layer over the first electrode, a second layer over the first layer, a light-emitting layer over the second layer, and a second electrode over the light-emitting layer, in which the first layer includes a first organic compound, the second layer includes a second organic compound, the first organic compound being a monoamine compound, the refractive index of the layer made of the first organic compound for light with a wavelength of 633 nm being 1.45 or more and 1.70 or less, and the second organic compound containing fluorine.

[0015] The second layer may further include a third organic compound, the highest occupied molecular orbital (HOMO) level of which is preferably lower than the HOMO level of the first organic compound.

[0016] The light-emitting device having any of the above configurations may further include a third layer. The third layer is located between the second layer and the light-emitting layer. The third layer includes a third organic compound. The HOMO level of the third organic compound is lower than the HOMO level of the first organic compound. In this case, the second layer may also further include the third organic compound.

[0017] Alternatively, one embodiment of the present invention is a light-emitting device including a first electrode, a first layer over the first electrode, a second layer over the first layer, a third layer over the second layer, a light-emitting layer over the third layer, and a second electrode over the light-emitting layer, in which the first layer includes a first organic compound, the second layer includes a second organic compound, and the third layer includes a third organic compound, the HOMO level of the third organic compound is lower than that of the first organic compound, the refractive index of the layer made of the first organic compound is lower than that of the layer made of the third organic compound, and the second organic compound contains fluorine.

[0018] The difference between the refractive index of the layer made of the first organic compound for light with a wavelength of 633 nm and the refractive index of the layer made of the third organic compound for light with a wavelength of 633 nm is preferably 0.05 or more, and more preferably 0.1 or more.

[0019] The second layer may further include a third organic compound.The third layer may further include a second organic compound.

[0020] The refractive index of the layer made of the first organic compound for light with a wavelength of 633 nm is preferably 1.45 or more and 1.70 or less.

[0021] The glass transition temperature of the first organic compound is preferably 90° C. or higher.

[0022] The first organic compound is preferably an amine compound, more preferably a monoamine compound.

[0023] The second organic compound preferably exhibits electron accepting properties toward the third organic compound.

[0024] In the third organic compound, the ratio of the number of carbon atoms forming bonds with sp3 hybrid orbitals to the total number of carbon atoms is preferably 23% or more and 55% or less.

[0025] The refractive index of the third layer made of the organic compound for light with a wavelength of 633 nm is preferably 1.45 or more and 1.70 or less.

[0026] The glass transition temperature of the third organic compound is preferably 90° C. or higher.

[0027] Preferably, the first layer is in contact with the second layer.

[0028] The light-emitting device having any of the above configurations may further include a fourth layer. The fourth layer is located between the first electrode and the first layer. The fourth layer includes a first organic compound and a second organic compound. The fourth layer is preferably in contact with the first electrode. The fourth layer is preferably in contact with the first layer.

[0029] The molecular weight of the first organic compound is preferably 650 or more and 1,200 or less.

[0030] The first organic compound is preferably a triarylmonoamine compound.

[0031] The first organic compound 1 In the H-NMR measurement results, the integral value of the signal below 4 ppm is preferably larger than the integral value of the signal at 4 ppm or more.

[0032] The first organic compound preferably has at least one hydrocarbon group having 1 to 12 carbon atoms.

[0033] The first organic compound preferably has at least one of an alkyl group having 3 to 8 carbon atoms and a cycloalkyl group having 6 to 12 carbon atoms.

[0034] The second organic compound preferably contains a cyano group.

[0035] The lowest unoccupied molecular orbital (LUMO) level of the second organic compound is preferably −5.0 eV or less.

[0036] The second organic compound preferably exhibits electron accepting properties with respect to the first organic compound.

[0037] The second organic compound preferably does not contain any metal element.

[0038] One embodiment of the present invention is a device including a light-emitting device having any of the above structures and at least one of a transistor and a substrate.

[0039] One embodiment of the present invention is a light-emitting module including the light-emitting device described above and at least one of a connector and an integrated circuit (IC). Examples of the connector include a flexible printed circuit (hereinafter referred to as FPC) and a tape carrier package (TCP). The IC can be mounted on the device by a chip-on-glass (COG) method or a chip-on-film (COF) method. The light-emitting module of one embodiment of the present invention may include either the connector or the IC, or both.

[0040] One embodiment of the present invention is an electronic device including the above-described light-emitting device and at least one of an antenna, a battery, a housing, a camera, a speaker, a microphone, and an operation button.

[0041] One embodiment of the present invention is a lighting device including a light-emitting device having any of the above structures and at least one of a housing, a cover, and a support base. [Effects of the Invention]

[0042] According to one embodiment of the present invention, a light-emitting device or a light-receiving / light-emitting device with high emission efficiency can be provided. According to one embodiment of the present invention, a light-emitting device or a light-receiving / light-emitting device with high light extraction efficiency can be provided. According to one embodiment of the present invention, a light-emitting device, a light-receiving device, or a light-emitting / light-receiving device with low driving voltage can be provided. According to one embodiment of the present invention, a light-emitting device, a light-receiving device, or a light-emitting / light-receiving device with high heat resistance can be provided. According to one embodiment of the present invention, a light-emitting device, a light-receiving device, or a light-emitting / light-receiving device with long lifetime can be provided. According to one embodiment of the present invention, a light-emitting device, a light-receiving device, or a light-emitting / light-receiving device with low power consumption can be provided.

[0043] Note that the description of these effects does not preclude the existence of other effects. One embodiment of the present invention does not necessarily have all of these effects. Effects other than these can be extracted from the description in the specification, drawings, and claims. [Brief explanation of the drawings]

[0044] [Figure 1] 1A to 1E are cross-sectional views showing an example of a light-emitting device. [Figure 2] Fig. 2A is a top view showing an example of a light emitting device, and Fig. 2B and Fig. 2C are cross-sectional views showing an example of a light emitting device. [Figure 3] 3A and 3C are cross-sectional views showing an example of a light emitting apparatus, and Fig. 3B is a cross-sectional view showing an example of a light emitting device. [Figure 4] 4A and 4B are cross-sectional views showing an example of a light emitting device. [Figure 5] Fig. 5A is a top view showing an example of a light emitting device, Fig. 5B is a cross-sectional view showing an example of a light emitting device, and Fig. 5C and Fig. 5D are cross-sectional views showing an example of a transistor. [Figure 6] 6A and 6B are cross-sectional views showing an example of a light receiving device, and Fig. 6C and Fig. 6D are diagrams showing an example of a light receiving and emitting device. [Figure 7] 7A to 7C are diagrams showing an example of a display device. [Figure 8] 8A to 8D are diagrams showing examples of electronic devices. [Figure 9] 9A to 9F are diagrams showing examples of electronic devices. [Figure 10] 10A to 10C are diagrams showing an example of an automobile. [Figure 11] 11A to 11E are diagrams showing an example of an electronic device. [Figure 12] FIG. 12 is a cross-sectional view showing a light-emitting device according to an embodiment. [Figure 13] FIG. 13 shows the measurement results of the refractive indexes of dchPAF and PCBBiF. [Figure 14] FIG. 14 is a graph showing the luminance-current density characteristics of the light-emitting device of Example 1. [Figure 15] FIG. 15 is a graph showing the current efficiency-luminance characteristics of the light-emitting device of Example 1. [Figure 16] FIG. 16 is a graph showing the current density-voltage characteristics of the light-emitting device of Example 1. [Figure 17] FIG. 17 is a graph showing the external quantum efficiency-luminance characteristics of the light-emitting device of Example 1. [Figure 18] FIG. 18 is a diagram showing the emission spectrum of the light-emitting device of Example 1. [Figure 19] FIG. 19 is a diagram showing the results of a reliability test of the light-emitting device of Example 1. As shown in FIG. [Figure 20] FIG. 20 is a diagram showing the measurement results of the refractive index of mmtBumTPoFBi-04. [Figure 21] FIG. 21 is a graph showing the luminance-current density characteristics of the light-emitting device of Example 2. [Figure 22] FIG. 22 is a graph showing the current efficiency-luminance characteristics of the light-emitting device of Example 2. [Figure 23] FIG. 23 is a graph showing the current density-voltage characteristics of the light-emitting device of Example 2. [Figure 24] FIG. 24 is a graph showing the external quantum efficiency-luminance characteristics of the light-emitting device of Example 2. [Figure 25]FIG. 25 is a diagram showing the emission spectrum of the light-emitting device of Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0045] The embodiments 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 can be made in form and detail 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.

[0046] In the configuration of the invention described below, the same parts or parts having similar functions are denoted by the same reference numerals in different drawings, and repeated explanations thereof will be omitted. In addition, when referring to similar functions, the same hatch pattern may be used and no particular reference numeral may be assigned.

[0047] Furthermore, for ease of understanding, the position, size, range, etc. of each component shown in the drawings may not represent the actual position, size, range, etc. Therefore, the disclosed invention is not necessarily limited to the position, size, range, etc. disclosed in the drawings.

[0048] It should be noted that the terms "film" and "layer" can be interchangeable depending on the circumstances. For example, the term "conductive layer" can be changed to the term "conductive film." Or, for example, the term "insulating film" can be changed to the term "insulating layer."

[0049] (Embodiment 1) In this embodiment, a light-emitting device of one embodiment of the present invention will be described with reference to FIGS.

[0050] The external quantum efficiency of organic EL devices can be increased by lowering the refractive index of the materials used. To obtain a material with a low refractive index, it is preferable to introduce a substituent with a low atomic refraction into the molecule. Examples of such a substituent include a chain saturated hydrocarbon group and a cyclic saturated hydrocarbon group. However, these substituents hinder the development of carrier transport properties. Therefore, it is difficult to achieve both high carrier transport properties and a low refractive index.

[0051] Furthermore, to improve the reliability of organic EL devices, it is desirable for the materials used in organic EL devices to have a high glass transition temperature (Tg). Increasing the glass transition temperature requires increasing the molecular weight of the material. One method for obtaining a material with high heat resistance and good reliability is to introduce unsaturated hydrocarbon groups, particularly cyclic unsaturated hydrocarbon groups, into the molecule. However, introducing a skeleton with an unsaturated bond into the molecule to increase the molecular weight increases the refractive index of the material. Thus, it is difficult to achieve both a high glass transition temperature and a low refractive index.

[0052] Among the hole-transporting materials that can be used in organic EL devices, 1,1-bis-(4-bis(4-methyl-phenyl)-amino-phenyl)cyclohexane (abbreviated as TAPC) is known to have a low refractive index. The use of TAPC is expected to lead to the creation of light-emitting devices with good external quantum efficiency.

[0053] Typically, there is a trade-off between high carrier transport and 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 high refractive indices. TAPC is a material that achieves an exquisite balance between carrier transport and low refractive index. On the other hand, compounds with a 1,1-disubstituted cyclohexane structure, such as TAPC, have two bulky substituents inserted on one carbon atom of cyclohexane, which increases steric repulsion and induces instability of the molecule itself, making them unreliable. Furthermore, TAPC's backbone structure, consisting of cyclohexane and a simple benzene ring, has a low glass transition temperature of 85°C and poor heat resistance.

[0054] As described above, it is not easy for a hole-transporting material to have both high carrier transport properties and a low refractive index, while also improving the glass transition temperature to enhance heat resistance or reliability during operation. To overcome this trade-off, the present inventors discovered an organic compound with a high glass transition temperature and a certain range of carbon atoms bonded by sp3 hybrid orbitals. They then discovered a light-emitting device configuration using a layer containing the organic compound, which has high luminous efficiency and low driving voltage.

[0055] Specifically, one embodiment of the present invention is a light-emitting device having a first electrode, a first layer on the first electrode, a second layer on the first layer, a light-emitting layer on the second layer, and a second electrode on the light-emitting layer. The first layer includes a first organic compound, and the second layer includes a second organic compound. In the first organic compound, the ratio of the number of carbon atoms forming bonds with sp3 hybrid orbitals to the total number of carbon atoms is 23% to 55%. The second organic compound contains fluorine.

[0056] Alternatively, one embodiment of the present invention is a light-emitting device including a first electrode, a first layer on the first electrode, a second layer on the first layer, an emitting layer on the second layer, and a second electrode on the emitting layer. The first layer includes a first organic compound, and the second layer includes a second organic compound. The glass transition temperature of the first organic compound is 90°C or higher. The refractive index of the layer made of the first organic compound for light with a wavelength of 633 nm is 1.45 or higher and 1.70 or lower. The second organic compound includes fluorine.

[0057] Another embodiment of the present invention is a light-emitting device including a first electrode, a first layer on the first electrode, a second layer on the first layer, an emitting layer on the second layer, and a second electrode on the emitting layer. The first layer includes a first organic compound, and the second layer includes a second organic compound. The first organic compound is a monoamine compound. The layer including the first organic compound has a refractive index of 1.45 or more and 1.70 or less for light with a wavelength of 633 nm. The second organic compound includes fluorine.

[0058] The first organic compound has a substituent (a chain saturated hydrocarbon group or a cyclic saturated hydrocarbon group, or both) composed of carbon atoms bonded with sp3 hybrid orbitals to reduce the refractive index. These substituents are often bulky, and as a result, the first layer is prone to create a carrier injection barrier (here, a hole injection barrier) between the first layer and adjacent layers.

[0059] Therefore, in a light-emitting device according to one embodiment of the present invention, a second layer containing a second organic compound is provided between the first layer and the light-emitting layer.

[0060] The second organic compound exhibits electron-accepting properties toward the first organic compound, which leads to an interaction between the first and second organic compounds, forming a charge-transfer complex, which facilitates hole injection from the first layer to the light-emitting layer.

[0061] In this way, by providing the second layer, hole transport from the first layer to the light-emitting layer can be facilitated, and the driving voltage of the light-emitting device can be reduced.

[0062] In particular, it is preferable that the second layer be provided in contact with the first layer. As described above, the first layer is prone to forming a hole injection barrier with the adjacent layer. By configuring the first layer and the second layer to be in contact with each other, this barrier can be reduced.

[0063] Alternatively, the second layer may include both the second organic compound and the third organic compound.

[0064] The second organic compound preferably exhibits electron-accepting properties toward the third organic compound. Furthermore, it is preferable that an interaction occurs between the second organic compound and the third organic compound to form a charge-transfer complex. This facilitates hole injection from the first layer to the light-emitting layer.

[0065] Alternatively, the second organic compound preferably exhibits electron-accepting properties toward both the first organic compound and the third organic compound. The second organic compound preferably interacts with at least one of the first organic compound and the third organic compound to form a charge-transfer complex. This facilitates hole injection from the first layer to the light-emitting layer.

[0066] The refractive index of the layer made of the first organic compound is preferably lower than the refractive index of the layer made of the third organic compound. In this case, the difference between the refractive index of the layer made of the first organic compound at a wavelength of 633 nm and the refractive index of the layer made of the third organic compound at a wavelength of 633 nm is preferably 0.05 or more, more preferably 0.1 or more, and even more preferably 0.15 or more.

[0067] As described above, the second organic compound may be an organic compound containing fluorine, and is preferably an organic compound containing a cyano group.

[0068] The lowest unoccupied molecular orbital (LUMO) level of the second organic compound is preferably −5.0 eV or less.

[0069] When the second organic compound emits light, the light emitted by the light-emitting material in the light-emitting layer decreases, thereby reducing the luminous efficiency of the light-emitting device. Therefore, it is preferable that light emission from the second organic compound is not observed.

[0070] When the difference between the highest occupied molecular orbital (HOMO) level of the first organic compound and that of the material (typically a host material) used in the light-emitting layer is large, the hole injection barrier becomes particularly high, and the driving voltage tends to increase. Even in this case, providing a second layer between the first layer and the light-emitting layer can facilitate hole transport from the first layer to the light-emitting layer, thereby lowering the driving voltage of the light-emitting device.

[0071] The third organic compound can be a hole-transporting material and an electron-blocking material. In particular, the third organic compound preferably has both hole-transporting and electron-blocking properties. The third organic compound preferably has low electron-injecting and electron-transporting properties.

[0072] The HOMO level of the third organic compound is preferably lower than that of the first organic compound, and the LUMO level of the third organic compound is preferably higher than that of the material having the lowest LUMO level among the materials contained in the light-emitting layer.

[0073] Furthermore, the light-emitting device of one embodiment of the present invention may include a third layer between the second layer and the light-emitting layer. The third layer includes a third organic compound. The third layer is preferably in contact with the second layer.

[0074] Consider the case where a third layer is provided on the first layer without providing a second layer. In this case, a higher HOMO level of the third organic compound can reduce the driving voltage of the light-emitting device. However, in the case of a light-emitting device that emits green or shorter wavelength phosphorescence, a high HOMO level of the third organic compound can easily form an exciplex between the third organic compound and the host material of the light-emitting layer, which can reduce the luminous efficiency. On the other hand, a lower HOMO level of the third organic compound can increase the luminous efficiency, but it also increases the hole injection barrier between the first and third layers, resulting in a higher driving voltage.

[0075] Furthermore, since the first organic compound has a substituent that inhibits carrier transport, such as a saturated hydrocarbon group that does not have a π orbital, the carrier injection ability into the third organic compound is significantly reduced, resulting in an increase in the driving voltage of the light-emitting device.

[0076] As described above, in the light-emitting device of one embodiment of the present invention, a second layer containing a second organic compound is provided between the first layer and the third layer. This facilitates hole transport from the first layer to the light-emitting layer even if the HOMO level of the third organic compound is low, thereby enabling the light-emitting device to achieve both high emission efficiency and low driving voltage. Alternatively, even if an organic compound with a low refractive index but poor carrier injection ability is used for the first layer, the hole transport from the first layer to the light-emitting layer can be facilitated, enabling the light-emitting device to achieve both high emission efficiency and low driving voltage.

[0077] The third layer may also include both the second organic compound and the third organic compound.

[0078] The above configuration can be applied not only to light-emitting devices but also to light-receiving devices such as organic photodiodes, and light-receiving and light-receiving devices that have both light-emitting and light-receiving functions.

[0079] The light-emitting device of one embodiment of the present invention may further include a fourth layer between the first electrode and the first layer. The fourth layer includes a first organic compound and a second organic compound.

[0080] For the light-emitting device of one embodiment of the present invention, the above-described composite material including the first organic compound and the second organic compound can be used.

[0081] The composite material can be used in a hole injection layer, a hole transport layer, a charge generation layer, etc. in a light-emitting device, or as a carrier transport material (hole transport material) in a light-receiving device, a light-emitting / receiving device, etc.

[0082] For example, the hole injection layer and charge generation layer of an organic EL device can each be made of a composite material containing a hole transport material and a material that has electron accepting properties relative to the hole transport material. In order for these layers to have hole injection or charge generation functions, interaction must occur between the materials constituting the composite material, resulting in the formation of a charge-transfer complex.

[0083] Here, if the composite material contains a large amount of a material having electron-accepting properties, light in the visible region is absorbed, which may reduce the light-emitting efficiency of the organic EL device. Therefore, it is preferable that the composite material contains a larger amount of a hole-transporting material than a material having electron-accepting properties. For example, a composite material in which a small amount of a material having electron-accepting properties is added to a hole-transporting material can be used in the light-emitting device of one embodiment of the present invention.

[0084] Furthermore, since lowering the refractive index of the materials used in organic EL devices increases the external quantum efficiency, it is desirable for the composite material to also have a low refractive index. If the refractive index of the first organic compound, which accounts for the majority of the composite material, is low, the refractive index of the composite material can be lowered.

[0085] [First organic compound] The ratio of the number of carbon atoms forming bonds with sp3 hybrid orbitals to the total number of carbon atoms in the first organic compound is preferably 23% or more and 55% or less. Substituents composed of carbon atoms forming bonds with sp3 hybrid orbitals are so-called chain saturated hydrocarbon groups or cyclic saturated hydrocarbon groups, and therefore have low atomic refraction. Therefore, the refractive index of the first organic compound can be reduced.

[0086] The glass transition temperature of the first organic compound is preferably 90°C or higher, more preferably 95°C or higher, more preferably 100°C or higher, more preferably 110°C or higher, and even more preferably 120°C or higher.

[0087] The first organic compound can maintain a high glass transition temperature and become a highly heat-resistant material by having a cyclic saturated hydrocarbon group or a rigid tertiary hydrocarbon group. Generally, the introduction of a saturated hydrocarbon group, particularly a chain saturated hydrocarbon group, tends to lower at least one of the glass transition temperature and melting point of the compound compared to a corresponding aromatic group or heteroaromatic group (e.g., with the same number of carbon atoms). A lower glass transition temperature may result in a lower heat resistance as an organic electroluminescent material. Since it is desirable for various devices using organic electroluminescent materials to exhibit stable physical properties under various usage environments, a material with equivalent properties preferably has a high glass transition temperature.

[0088] The refractive index of the layer made of the first organic compound at a wavelength of 633 nm is preferably 1.45 or more and 1.70 or less. 633 nm is a wavelength commonly used for measuring refractive index. The refractive index of the layer made of the first organic compound at wavelengths 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. The refractive index of the layer made of the first organic compound at wavelengths in the green light-emitting region (525 nm or more and 535 nm or less) is preferably 1.48 or more and 1.73 or less. When anisotropy occurs in a material, the refractive index for ordinary light and the refractive index for extraordinary light may differ. In this case, anisotropy analysis can be performed to separate the ordinary and extraordinary refractive indices and calculate the respective refractive indices. In this specification, when the measured material has both ordinary and extraordinary refractive indices, the ordinary refractive index is used as the index.

[0089] The refractive index of the layer made of the first organic compound may be evaluated using the refractive index at the peak wavelength of light emitted by a light-emitting device using the first organic compound or the peak emission wavelength of a light-emitting substance contained in the light-emitting device. In this case, the refractive index of the layer made of the first organic compound is preferably 1.50 to 1.75, 1.48 to 1.73, or 1.45 to 1.70. When a light-adjusting structure such as a color filter is provided, the peak wavelength of the light emitted by the light-emitting device is the peak wavelength of the light before passing through the structure. The peak emission wavelength of the light-emitting substance is calculated from the PL spectrum in a solution state. Since the relative dielectric constant of the organic compound constituting the EL layer of the light-emitting device is approximately 3, to avoid discrepancies with the emission spectrum of the light-emitting device, the relative dielectric constant of the solvent used to put the light-emitting center substance into solution is preferably 1 to 10 at room temperature, more preferably 2 to 5. Specific examples of the solution include hexane, benzene, toluene, diethyl ether, ethyl acetate, chloroform, chlorobenzene, and dichloromethane. The solution is preferably a general-purpose solvent that has a high solubility and a relative dielectric constant at room temperature of 2 or more and 5 or less. For example, toluene or chloroform is preferably used as the solution.

[0090] The first organic compound is preferably an amine compound, more preferably a monoamine compound, and even more preferably a triarylmonoamine compound.

[0091] It is preferable that the first organic compound is an amine compound, since the HOMO level can be easily controlled to a desired height depending on the substitution position of the alkyl group.

[0092] The first organic compound preferably has an alkyl group bonded to the same plane as or in the vicinity of the plane that forms the HOMO. In other words, it is preferable to position the alkyl group at a position where the HOMO is not blocked. When the first organic compound is an aromatic amine compound, the plane that forms the HOMO can be the plane of the aromatic ring to which nitrogen is bonded. The alkyl group is preferably a tert-butyl group or a cyclohexyl group.

[0093] The first organic compound preferably has an alkyl group that functions as an electron-donating group at a bonding position that further destabilizes the HOMO energy. For example, it is preferable to have an alkyl group at the para-position of the nitrogen atom of triphenylamine. This makes it possible to raise (shallow) the HOMO level of the first organic compound.

[0094] The first organic compound preferably has a skeleton with high carrier transport properties, and aromatic amine skeletons are particularly preferred due to their high hole transport properties. To further improve carrier transport properties, it is possible to introduce two amine skeletons. However, as in the case of TAPC mentioned above, depending on the substituents placed around it, the diamine structure may have a negative effect on reliability.

[0095] We have discovered a monoamine compound with a specific range of carbon atoms bonded via sp3 hybrid orbitals, which overcomes the trade-off and combines high carrier transport properties, a low refractive index, and high reliability. In particular, this monoamine compound exhibits excellent reliability comparable to conventional hole-transport materials with normal refractive indices. Furthermore, by optimizing at least one of the number and substitution position of the substituents (e.g., alkyl groups and cycloalkyl groups) containing carbon atoms bonded via sp3 hybrid orbitals in the monoamine compound, it is possible to obtain a material with even better properties. In the monoamine compound, limiting the number of aromatic groups bonded to the saturated hydrocarbon group reduces steric repulsion, thereby improving molecular stability. This allows for the development of optical devices with long lifetimes.

[0096] The molecular weight of the first organic compound is preferably not less than 650 and not more than 1200. This can improve the heat resistance of the first organic compound.

[0097] The first organic compound 1 In the H-NMR measurement results, the integral value of the signal below 4 ppm is preferably larger than the integral value of the signal at 4 ppm or more.

[0098] Signals below 4 ppm reflect hydrogen atoms in chain or cyclic saturated hydrocarbon groups, and if they are greater than the integral value of signals above 4 ppm, it means that the number of hydrogen atoms constituting saturated hydrocarbon groups is greater than the number of hydrogen atoms constituting unsaturated hydrocarbons. This allows us to estimate the proportion of sp3 carbons in the molecule. Here, carbon atoms in unsaturated hydrocarbon groups have fewer bonds that can bond with hydrogen. For example, comparing benzene and cyclohexane, the difference between C6H6 and C6H 12 Considering this difference, 1 In the results of H-NMR measurement, the integral value of the signal below 4 ppm is greater than the integral value of the signal above 4 ppm, which means that about one-third of the carbon atoms constituting the molecule belong to saturated hydrocarbon groups. As a result, the first organic compound has a low refractive index and can be suitably used as a hole transport material.

[0099] An example of the first organic compound is a monoamine compound having a first aromatic group, a second aromatic group, and a third aromatic group, in which the first aromatic group, the second aromatic group, and the third aromatic group are directly bonded to the same nitrogen atom.

[0100] The monoamine compound preferably has at least one fluorene skeleton, since it has good hole transport properties. Therefore, it is preferable that one or more of the first aromatic group, the second aromatic group, and the third aromatic group described above is a fluorene skeleton. In addition, the direct bonding of the fluorene skeleton to the nitrogen atom of the amine contributes to increasing the HOMO level of the molecule, facilitating the transfer of holes.

[0101] The first aromatic group and the second aromatic group each independently have one to three benzene rings. Preferably, both the first aromatic group and the second aromatic group are hydrocarbon groups. That is, the first aromatic group and the second aromatic group are preferably phenyl, biphenyl, terphenyl, or naphthylphenyl groups, respectively. Preferably, the first aromatic group or the second aromatic group is a terphenyl group, since this improves the glass transition temperature and improves heat resistance.

[0102] When the first aromatic group and the second aromatic group each have two or three benzene rings, the two or three benzene rings are preferably bonded to each other. Note that if one or both of the first aromatic group and the second aromatic group is a substituent in which two or three benzene rings are bonded to each other, i.e., a biphenyl group or a terphenyl group, this is preferred because it improves the glass transition temperature and improves heat resistance, and it is more preferred that the first aromatic group and the second aromatic group are each independently a biphenyl group or a terphenyl group.

[0103] One or both of the first aromatic group and the second aromatic group preferably have one or more hydrocarbon groups having 1 to 12 carbon atoms in which carbon atoms form bonds only through sp3 hybrid orbitals. As the hydrocarbon group, alkyl groups having 3 to 8 carbon atoms and cycloalkyl groups having 6 to 12 carbon atoms are preferred.

[0104] The total number of carbon atoms contained in the hydrocarbon groups bonded to the first aromatic group or the second aromatic group is 6 or more. The total number of carbon atoms contained in all of the hydrocarbon groups bonded to the first aromatic group and the second aromatic group is 8 or more, preferably 12 or more. By bonding the hydrocarbon groups with small atomic refraction in this manner, the monoamine compound can be an organic compound with a small refractive index.

[0105] In addition, a larger number of π electrons derived from unsaturated bonds of carbon atoms is advantageous for carrier transport. The total number of carbon atoms contained in all of the hydrocarbon groups bonded to the first aromatic group and the second aromatic group is preferably 36 or less, and more preferably 30 or less, in order to maintain good carrier transport properties.

[0106] The third aromatic group is a substituted or unsubstituted monocyclic ring or a substituted or unsubstituted fused ring having three or less rings. Increasing the number of fused rings tends to increase the refractive index. Furthermore, increasing the number of fused rings tends to result in the observation of either or both of absorption and emission of light in the visible region. Therefore, by limiting the number of fused rings to three or less, a low refractive index can be maintained and a material with minimal effects of absorption and emission can be obtained. In order to maintain a low refractive index, the third aromatic group preferably has 6 to 13 carbon atoms forming the ring. Specific examples of the third aromatic group include a benzene ring, a naphthalene ring, a fluorene ring, and an acenaphthylene ring. In particular, the third aromatic group preferably contains a fluorene ring, and more preferably a fluorene ring, since this provides good hole transport properties.

[0107] For example, the first organic compound can be any of the organic compounds represented by General Formulas (G1) to (G4). The organic compounds represented by General Formulas (G1) to (G4) can be considered as examples of monoamine compounds and examples of triarylmonoamine compounds.

[0108] [ka]

[0109] In general formula (G1), Ar 1 and Ar 2 each independently 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. 1 and 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 hydrocarbon groups bonded to Ar is 8 or more, and 1 and Ar 2 The total number of carbon atoms in all hydrocarbon groups bonded to either R is 6 or more. 1 ~R 3 each independently represents an alkyl group having 1 to 4 carbon atoms, and u represents an integer of 0 to 4. 1 and R 2 may be bonded to each other to form a ring.

[0110] Ar 1 and Ar 2 Specific examples of the phenyl group include a substituted or unsubstituted phenyl group, a biphenyl group, a terphenyl group, and a naphthylphenyl group.

[0111] As the hydrocarbon group having 1 to 12 carbon atoms in which carbon atoms form bonds only through sp3 hybrid orbitals, an alkyl group having 3 to 8 carbon atoms and a cycloalkyl group having 6 to 12 carbon atoms are preferred. Specific examples include a propyl group, an isopropyl group, a butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a neopentyl group, a hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, a neohexyl group, a heptyl group, an octyl group, a cyclohexyl group, a 4-methylcyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, a decahydronaphthyl group, a cycloundecyl group, and a cyclododecyl group. A tert-butyl group, a cyclohexyl group, and a cyclododecyl group are particularly preferred.

[0112] In addition, 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.

[0113] [ka]

[0114] In general formula (G2), n, m, p, and r each independently represent 1 or 2, and s, t, and u each independently represent an integer of 0 to 4. Furthermore, n+p and m+r each independently represent 2 or 3. R 1 ~R 3 each independently represents an alkyl group having 1 to 4 carbon atoms, and R 4 and R 5 each independently represents hydrogen or a hydrocarbon group having 1 to 3 carbon atoms; R 10 ~R 14 and R 20 ~R 24 R each 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 and R 20 ~R 24 The total number of carbon atoms in R is 8 or more, and 10 ~R 14 or R 20 ~R 24 The total number of carbon atoms in either of the two is 6 or more. 1 and R 2 may be bonded to each other to form a ring, and R 4 , R 5 , R 10 ~R 14 , and R 20 ~R 24 Adjacent groups may be bonded to each other to form a ring.

[0115] [ka]

[0116] In general formula (G3), n and p each independently represent 1 or 2, and s and u each independently represent an integer of 0 to 4. Furthermore, n+p is 2 or 3. 1 ~R 3 each independently represents an alkyl group having 1 to 4 carbon atoms, and R 4 represents hydrogen or a hydrocarbon group having 1 to 3 carbon atoms, and R 10 ~R 14 and R 20 ~R 24 R each 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 and R 20 ~R 24 The total number of carbon atoms in R is 8 or more, and 10 ~R 14 or R 20 ~R 24 The total number of carbon atoms in either of the two groups is 6 or more. 1 and R 2 may be bonded to each other to form a ring, and R4 , R 10 ~R 14 , and R 20 ~R 24 Adjacent groups may be bonded to each other to form a ring.

[0117] In general formula (G2) and general formula (G3), examples of the hydrocarbon group having 1 to 3 carbon atoms include a methyl group, an ethyl group, and a propyl group. Examples of the hydrocarbon group having 1 to 4 carbon atoms include a butyl group in addition to the above.

[0118] In general formula (G2) and general formula (G3), when n is 2, the types of substituents, the number of substituents, and the positions of the bonds of the two phenylene groups may be the same or different. Similarly, when any of m, p, and r is 2, the types of substituents, the number of substituents, and the positions of the bonds of the two phenylene groups may be the same or different.

[0119] It is preferable that s, t, and u are each independently 0. When s is an integer of 2 or more and 4 or less, a plurality of R 4 may be the same or different, and when t is an integer of 2 or more and 4 or less, a plurality of R 5 may be the same or different, and when u is an integer of 2 or more and 4 or less, a plurality of R 3 may be the same or different.

[0120] [ka]

[0121] In general formula (G4), u represents an integer of 0 or more and 4 or less, and R 1 ~R 3 each independently represents an alkyl group having 1 to 4 carbon atoms, and R 10 ~R 14 and R 20 ~R 24R each 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 and R 20 ~R 24 The total number of carbon atoms in R is 8 or more, and 10 ~R 14 or R 20 ~R 24 The total number of carbon atoms in either of the two groups is 6 or more. 1 and R 2 may be bonded to each other to form a ring, and R 10 ~R 14 , and R 20 ~R 24 Adjacent groups may be bonded to each other to form a ring.

[0122] It is preferable that u is 0. When u is an integer of 2 or more and 4 or less, a plurality of R 3 may be the same or different.

[0123] In the general formulae (G2) to (G4), R 10 ~R 14 and R 20 ~R 24 are preferably each independently any one of hydrogen, a tert-butyl group, and a cyclohexyl group, since this can lower the refractive index. 10 ~R 14 At least three of the above, and R 20 ~R 24 When at least three of the above are hydrogen, the carrier transport property is less likely to be hindered, which is preferable.

[0124] An example of the first organic compound 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, where the first to third benzene rings are bonded in this order and the first benzene ring is directly bonded to a nitrogen atom of the amine.

[0125] The first benzene ring may further have a substituted or unsubstituted phenyl group, preferably an unsubstituted phenyl group, and the second or third benzene ring may have a phenyl group substituted with an alkyl group.

[0126] It should be noted that 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, are not directly bonded to hydrogen but are 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 atom of the amine.

[0127] 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 with three or less rings, more preferably a substituted or unsubstituted fused ring with three or less rings, 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.

[0128] The arylamine compound preferably further comprises a third aromatic group, the third aromatic group comprising one to three substituted or unsubstituted benzene rings.

[0129] The at least three alkyl groups and the alkyl groups substituting the phenyl groups are preferably chain alkyl groups having from 2 to 5 carbon atoms, more preferably branched chain alkyl groups having from 3 to 5 carbon atoms, and even more preferably tert-butyl groups.

[0130] For example, the first organic compound can be any of the organic compounds represented by General Formulas (G11) to (G13). The organic compounds represented by General Formulas (G11) to (G13) can be considered as examples of monoamine compounds and examples of triarylmonoamine compounds.

[0131] [ka]

[0132] In general formula (G11), 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, and R 106 ~R 108 each independently represents an alkyl group having 1 to 4 carbon atoms, v represents an integer of 0 to 4, and R 111 ~R 115 Among these, one represents a substituent represented by general formula (g1), and the others each independently represent one of hydrogen, an alkyl group having 1 to 6 carbon atoms, and a substituted or unsubstituted phenyl group. 111 ~R 115 The number of substituted or unsubstituted phenyl groups in the formula (I) is 1 or less. The phenyl group is preferably unsubstituted. When the phenyl group has a substituent, the substituent is an alkyl group having 1 to 6 carbon atoms.

[0133] Ar 101 Specific examples of the phenyl group include a substituted or unsubstituted phenyl group, a biphenyl group, a terphenyl group, and a naphthylphenyl group.

[0134] In addition, when v is 2 or more, multiple R 108 may be the same or different.

[0135] In general formula (g1), R 121 ~R 125Among these, one represents a substituent represented by general formula (g2), and the others 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.

[0136] In general formula (g2), R 131 ~R 135 each 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.

[0137] R 111 ~R 115 , R 121 ~R 125 , and R 131 ~R 135 Among these, at least three or more are alkyl groups having a carbon number of 1 to 6. This allows the organic compound represented by the general formula (G11) to be an arylamine compound having a low refractive index.

[0138] R 121 ~R 125 and R 131 ~R 135 In the formula (I), the number of phenyl groups substituted with alkyl groups having 1 to 6 carbon atoms is one or less, i.e., R 121 ~R 125 and R 131 ~R 135 Among these, the number of phenyl groups substituted with alkyl groups having 1 to 6 carbon atoms is 1 or 0.

[0139] In addition, R 112 and R 114 , R 122 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. 112 and R 114 a benzene ring having R 122 and R 124 a benzene ring having R132 and R 134 In two or more of the benzene rings, at least one of the meta-position carbon atoms is not hydrogen, i.e., it has a substituent. 112 , R 114 , R 122 , R 124 is other than hydrogen, and R 132 and R 134 It is preferred that at least one of these is other than hydrogen.

[0140] Examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, and an isobutyl group, with a tert-butyl group being particularly preferred.

[0141] When the benzene ring or phenyl group has a substituent, the substituent can be an alkyl group having 1 to 6 carbon atoms, or a cycloalkyl group having 5 to 12 carbon atoms.

[0142] The alkyl group having 1 to 6 carbon atoms is preferably a chain alkyl group having 2 or more carbon atoms from the viewpoint of reducing the refractive index, and is preferably a chain alkyl group having 5 or less carbon atoms from the viewpoint of ensuring carrier transportability. Furthermore, a branched chain alkyl group having 3 or more carbon atoms has a remarkable effect of reducing the refractive index. That is, the alkyl group having 1 to 6 carbon atoms is preferably a chain alkyl group having 2 to 5 carbon atoms, and is more preferably a branched chain alkyl group having 3 to 5 carbon atoms. Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, and a hexyl group, and a tert-butyl group is particularly preferred.

[0143] Examples of cycloalkyl groups having 5 to 12 carbon atoms include cyclohexyl, 4-methylcyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, decahydronaphthyl, cycloundecyl, and cyclododecyl groups. Cycloalkyl groups having 6 or more carbon atoms are preferred for achieving a low refractive index, and cyclohexyl and cyclododecyl groups are particularly preferred.

[0144] General formula (G12) is a compound represented by the formula (G11) in which Ar 101 is an example of a substituent in which two or three substituted or unsubstituted benzene rings are bonded to each other. Therefore, explanations of the same parts as in general formula (G11) may be omitted.

[0145] [ka]

[0146] In general formula (G12), R 106 ~R 109 each independently represents an alkyl group having 1 to 4 carbon atoms, v and w each independently represent an integer of 0 to 4, x and y each independently represent 1 or 2, and x+y is 2 or 3. Preferably, both x and y are 1. R 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.

[0147] In addition, when v is 2 or more, multiple R 108 Similarly, when w is 2 or more, multiple R 109 may be the same or different.

[0148] When x is 2, the types and numbers of substituents on the two phenylene groups and the positions of the bonds may be the same or different, and when y is 2, the types and numbers of substituents on the two phenyl groups may be the same or different.

[0149] General formula (G13) is a compound represented by the formula (G11) in which Ar 101 is an example of a compound having one substituted or unsubstituted benzene ring. Therefore, explanations of the same parts as in general formula (G11) may be omitted.

[0150] [ka]

[0151] In general formula (G13), R 101 ~R 105 each 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.

[0152] R 101 ~R 105 Among them, R 103 It is preferred that R is a cyclohexyl group and the rest are all hydrogen. 101 ~R 105 Among them, R 101 is an unsubstituted phenyl group and the rest are all hydrogen atoms, which is preferable because it improves the hole transporting property.

[0153] Specific examples of organic compounds that can be used as the first organic compound include N,N-bis(4-cyclohexylphenyl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: dchPAF), N-[(3',5'-ditertiarybutyl)-1,1'-biphenyl-4-yl]-N-(4-cyclohexylphenyl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBuBichPAF), N-(3,3'',5,5''-tetra-t-butyl-1,1':3',1''-terphenyl-5'-yl)-N-(4-cyclohexylphenyl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBuBichPAF), and N-(3,3'',5,5''-tetra-t-butyl-1,1':3',1''-terphenyl-5'-yl)-N-(4-cyclohexylphenyl)-9,9-dimethyl-9H-fluoren-2-amine. N-[(3,3',5'-t-butyl)-1,1'-biphenyl-5-yl]-N-(4-cyclohexylphenyl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPchPAF), N-[(3,3',5'-t-butyl)-1,1'-biphenyl-5-yl]-N-(4-cyclohexylphenyl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumBichPAF), N-(1,1'-biphenyl-2-yl)-N-[(3,3',5'-tri-t-butyl)-1,1'-biphenyl-5-yl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumBioFBi), N-(4-tert-butylphenyl)-N-(3,3'',5,5''-tetra-t-butyl-1,1':3',1''-terphenyl-5'-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPtBuPAF), 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), N-(4-cyclohexylphenyl)-N- (3,3'',5',5''-tetra-t-butyl-1,1':3',1''-terphenyl-5-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPchPAF-02), N-(1,1'-biphenyl-2-yl)-N-(3'',5',5''-tri-t-butyl-1,1':3',1''-terphenyl-5-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPoFBi-03), N-(4-cyclohexylphenyl)-N-(3'',5',5''-tri-t-butyl-1,Examples include N-(1,1'-biphenyl-2-yl)-N-(3'',5',5''-tri-t-butyl-1,1':3',1''-terphenyl-4-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPchPAF-03), N-(1,1'-biphenyl-2-yl)-N-(3'',5',5''-tri-t-butyl-1,1':3',1''-terphenyl-4-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPoFBi-04), and N-(4-cyclohexylphenyl)-N-(3'',5',5''-tri-t-butyl-1,1':3',1''-terphenyl-4-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPchPAF-04). The synthesis methods for these organic compounds are described in detail in the Reference Examples.

[0154] [Second organic compound] As described above, the second organic compound contains fluorine. It is particularly preferable that the second organic compound contains a cyano group.

[0155] The second organic compound preferably exhibits electron accepting properties with respect to the first organic compound, and therefore the LUMO level of the second organic compound is preferably −5.0 eV or less.

[0156] Specific examples of the second organic compound include 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), 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. Furthermore, radialene derivatives having an electron-withdrawing group (particularly a halogen group such as a fluoro group, or a cyano group) are 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].

[0157] Furthermore, it is preferable that the second organic compound does not contain a metal element, since this facilitates deposition.

[0158] In the case where the third organic compound is used in the light-emitting device of one embodiment of the present invention, the second organic compound preferably exhibits electron accepting properties with respect to the third organic compound.

[0159] As described above, a composite material of a first organic compound and a second organic compound can be used in a light-emitting device according to one embodiment of the present invention. The mass percent concentration of the second organic compound in the composite material is preferably 10 wt% or less, more preferably 5 wt% or less. Alternatively, the volume percent concentration of the second organic compound in the composite material is preferably 10 vol% or less, more preferably 5 vol% or less, and even more preferably 3 vol% or less. By lowering the concentration of the second organic compound, absorption of light in the visible region can be suppressed. This can increase the emission efficiency of the light-emitting device, for example. Furthermore, when a layer containing the composite material is formed in common among multiple light-emitting devices included in a light-emitting device, crosstalk can be suppressed.

[0160] [Third organic compound] As the third organic compound, a hole transporting material and an electron blocking material can be used. In particular, the third organic compound preferably has both hole transporting and electron blocking properties. Among the hole transporting materials described below, it is preferable to use a material having electron blocking properties. The third organic compound preferably has low electron injection and electron transport properties.

[0161] The HOMO level of the third organic compound is preferably lower than the HOMO level of the first organic compound, and therefore the HOMO level of the third organic compound is preferably −5.40 eV or lower.

[0162] The LUMO level of the third organic compound is preferably higher than the LUMO level of the material with the lowest LUMO level among the materials contained in the light-emitting layer, and therefore the LUMO level of the third organic compound is preferably −2.50 eV or higher.

[0163] The third organic compound can be a compound that can be used for the first organic compound, or a hole transporting material, which will be described later.

[0164] The refractive index of the layer made of the first organic compound is preferably lower than the refractive index of the layer made of the third organic compound. In this case, the difference between the refractive index of the layer made of the first organic compound at a wavelength of 633 nm and the refractive index of the layer made of the third organic compound at a wavelength of 633 nm is preferably 0.05 or more, more preferably 0.1 or more, and even more preferably 0.15 or more.

[0165] Alternatively, the refractive index of the layer made of the third organic compound at light with a wavelength of 633 nm is preferably 1.45 or more and 1.70 or less. Furthermore, the refractive index of the layer made of the third organic compound at wavelengths in the green light-emitting region (525 nm or more and 535 nm or less) is preferably 1.48 or more and 1.73 or less. Furthermore, the refractive index of the layer made of the third organic compound at wavelengths 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.

[0166] To achieve this, the ratio of the number of carbon atoms forming bonds with sp3 hybrid orbitals to the total number of carbon atoms in the third organic compound is preferably 23% or more and 55% or less. Substituents composed of carbon atoms forming bonds with sp3 hybrid orbitals are so-called chain saturated hydrocarbon groups or cyclic saturated hydrocarbon groups, and therefore have low atomic refraction. Therefore, the refractive index of the third organic compound can be reduced.

[0167] The glass transition temperature of the third organic compound is preferably 90°C or higher, more preferably 95°C or higher, more preferably 100°C or higher, more preferably 110°C or higher, and even more preferably 120°C or higher.

[0168] The third organic compound is preferably an amine compound, more preferably a monoamine compound, and even more preferably a triarylmonoamine compound.

[0169] The molecular weight of the third organic compound is preferably 650 or more and 1200 or less, which can improve the heat resistance of the first organic compound.

[0170] The third organic compound 1 In the H-NMR measurement results, the integral value of the signal below 4 ppm is preferably larger than the integral value of the signal at 4 ppm or more.

[0171] For specific examples of the third organic compound, the above description of the first organic compound can be referred to.

[0172] [Example of light-emitting device configuration] <Basic structure of light-emitting devices> 1A to 1E show an example of a light-emitting device having an EL layer between a pair of electrodes.

[0173] 1A has a structure (single structure) in which an EL layer 103 is sandwiched between a first electrode 101 and a second electrode 102. The EL layer 103 has at least an emitting layer. The EL layer 103 may further have one or more layers selected from various layers such as a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, a carrier blocking layer, an exciton blocking layer, and a charge generation layer.

[0174] FIG. 1B shows an example of a stacked structure of the EL layer 103. In this embodiment, a case where the first electrode 101 functions as an anode and the second electrode 102 functions as a cathode will be described as an example. The EL layer 103 has a structure in which a hole injection layer 111, a first hole transport layer 112a, a buffer layer 119, a second hole transport layer 112b, a light-emitting layer 113, an electron transport layer 114, and an electron injection layer 115 are stacked in this order on the first electrode 101. Each of the hole injection layer 111, the first hole transport layer 112a, the buffer layer 119, the second hole transport layer 112b, the light-emitting layer 113, the electron transport layer 114, and the electron injection layer 115 may have a single-layer structure or a stacked structure. When the first electrode 101 is a cathode and the second electrode 102 is an anode, the stacking order is reversed.

[0175] The first hole-transport layer 112a can be the first layer described above, and the buffer layer 119 can be the second layer described above. The second hole-transport layer 112b is preferably the third layer described above. The hole-injection layer 111 is preferably the fourth layer described above.

[0176] The organic compound used for the buffer layer 119 and the organic compound used for the second hole-transport layer 112b may be mixed. Alternatively, the buffer layer 119 may not be provided, and the organic compound used for the buffer layer 119 may be added to the second hole-transport layer 112b. Alternatively, the second hole-transport layer 112b may not be provided, and the organic compound used for the second hole-transport layer 112b may be added to the buffer layer 119.

[0177] The light-emitting device may have multiple EL layers between a pair of electrodes. For example, the light-emitting device preferably has n EL layers (n is an integer of 2 or more) and has a charge generation layer 104 between the (n-1)th EL layer and the nth EL layer.

[0178] Fig. 1C shows a light-emitting device with a tandem structure having two EL layers (EL layers 103a and 103b) between a pair of electrodes, and Fig. 1D shows a light-emitting device with a tandem structure having three EL layers (EL layers 103a, 103b, and 103c).

[0179] Each of the EL layers 103a, 103b, and 103c includes at least an emissive layer. When multiple EL layers are included, such as in the tandem structure shown in FIGS. 1C and 1D, a stacked structure similar to that of the EL layer 103 shown in FIG. 1B can be applied to at least one of the EL layers. In particular, applying a stacked structure similar to that of the EL layer 103 shown in FIG. 1B to the EL layer that emits green phosphorescence is preferable, since it can achieve both high luminous efficiency and low driving voltage. Each of the EL layers 103a, 103b, and 103c can include one or more layers selected from the group consisting of a hole injection layer 111, a first hole transport layer 112a, a buffer layer 119, a second hole transport layer 112b, an electron transport layer 114, and an electron injection layer 115.

[0180] 1C has the function of injecting electrons into one of the EL layers 103a and 103b and injecting holes into the other when a voltage is applied between the first electrode 101 and the second electrode 102. Therefore, in FIG. 1C, when a voltage is applied to the first electrode 101 so that the potential of the first electrode 101 is higher than that of the second electrode 102, electrons are injected from the charge generation layer 104 into the EL layer 103a and holes are injected into the EL layer 103b.

[0181] From the viewpoint of light extraction efficiency, the charge generation layer 104 preferably transmits visible light or near-infrared light (specifically, the transmittance of the charge generation layer 104 for visible light or near-infrared light is 40% or more). The charge generation layer 104 functions even if it has lower conductivity than one or both of the first electrode 101 and the second electrode 102.

[0182] Note that, when the EL layers are provided in contact with each other and the same structure as the charge generation layer 104 is formed between them, the EL layers can be provided in contact with each other without a charge generation layer therebetween. For example, when a charge generation region is formed on one surface of the EL layer, the EL layer can be provided in contact with that surface.

[0183] Tandem-structure light-emitting devices have higher current efficiency than single-structure devices and require less current to emit light at the same brightness, which extends the life of the light-emitting devices and improves the reliability of light-emitting devices and electronic devices.

[0184] The light-emitting layer 113 may contain an appropriate combination of a light-emitting material and other materials, enabling it to emit fluorescent or phosphorescent light at a desired wavelength. The light-emitting layer 113 may also have a stacked structure with layers that emit different light wavelengths. In this case, different materials may be used for the light-emitting material and other materials in each stacked light-emitting layer. The EL layers 103a, 103b, and 103c shown in FIGS. 1C and 1D may emit light of different wavelengths. In this case, different materials may be used for the light-emitting material and other materials in each light-emitting layer. For example, in FIG. 1C, the EL layer 103a may emit red and green light, and the EL layer 103b may emit blue light, thereby achieving a light-emitting device that emits white light as a whole. A single light-emitting device may also have multiple light-emitting or EL layers that emit the same color. For example, in FIG. 1D, by configuring EL layer 103a to emit a first blue light, EL layer 103b to emit yellow, yellow-green, or green light and red light, and EL layer 103c to emit a second blue light, it is possible to obtain a light-emitting device that emits white light as a whole.

[0185] In the light-emitting device according to one embodiment of the present invention, the light emitted from the EL layer may be resonated between a pair of electrodes to enhance the light emission. For example, in FIG. 1B, the first electrode 101 is a reflective electrode and the second electrode 102 is a semi-transparent and semi-reflective electrode, thereby forming a micro-optical resonator (microcavity) structure, which enhances the light emission from the EL layer 103.

[0186] By applying a microcavity structure to a light-emitting device, it is possible to extract light of different wavelengths (monochromatic light) even if the device has the same EL layer. This eliminates the need to form different functional layers for each pixel (so-called separate coating) to obtain different emitted colors. This makes it easy to achieve high resolution. It can also be combined with a colored layer (color filter). Furthermore, it is possible to increase the emission intensity of a specific wavelength in the front direction, thereby reducing power consumption.

[0187] When the first electrode 101 of the light-emitting device is a reflective electrode having a laminated structure of a conductive film reflective to visible light or near-infrared light and a conductive film transmissive to visible light or near-infrared light, optical adjustment can be performed by controlling the film thickness of the transmissive conductive film. Specifically, it is preferable to adjust the inter-electrode distance between the first electrode 101 and the second electrode 102 to be approximately mλ / 2 (where m is a natural number) for the wavelength λ of light obtained from the light-emitting layer 113.

[0188] Furthermore, in order to amplify the desired light (wavelength: λ) obtained from the light-emitting layer 113, it is preferable to adjust the optical distance from the first electrode 101 to the region (light-emitting region) in the light-emitting layer 113 where the desired light is obtained and the optical distance from the second electrode 102 to the region (light-emitting region) in the light-emitting layer 113 where the desired light is obtained to be approximately (2m'+1)λ / 4 (where m' is a natural number). Note that the light-emitting region here refers to the recombination region of holes and electrons in the light-emitting layer 113.

[0189] By performing such optical adjustment, the spectrum of the light obtained from the light-emitting layer 113 can be narrowed, and light emission with good color purity can be obtained.

[0190] In the above case, the optical distance between the first electrode 101 and the second electrode 102 can be strictly defined as the total thickness from the reflective region of the first electrode 101 to the reflective region of the second electrode 102. However, since it is difficult to precisely determine the reflective region of the electrodes, the above-mentioned effect can be sufficiently achieved by assuming any position of the first electrode 101 or the second electrode 102 as the reflective region. Furthermore, the optical distance between the first electrode 101 and the light-emitting layer from which desired light is obtained can be strictly defined as the optical distance between the reflective region of the first electrode 101 and the light-emitting region of the light-emitting layer from which desired light is obtained. However, since it is difficult to precisely determine the reflective region of the first electrode 101 and the light-emitting region of the light-emitting layer from which desired light is obtained, the above-mentioned effect can be sufficiently achieved by assuming any position of the first electrode 101 as the reflective region and any position of the light-emitting layer from which desired light is obtained as the light-emitting region.

[0191] At least one of the first electrode 101 and the second electrode 102 is an electrode that is transparent to visible light or near-infrared light. The electrode that is transparent to visible light or near-infrared light has a transmittance of 40% or more for visible light or near-infrared light. When the electrode that is transparent to visible light or near-infrared light is the semi-transparent / semi-reflective electrode, the electrode has a reflectance of 20% or more and 80% or less, preferably 40% or more and 70% or less for visible light or near-infrared light. The resistivity of these electrodes is 1×10 -2 Ωcm or less is preferable.

[0192] When the first electrode 101 or the second electrode 102 is an electrode (reflective electrode) that is reflective to visible light or near-infrared light, the reflectance of the reflective electrode to visible light or near-infrared light is set to 40% or more and 100% or less, preferably 70% or more and 100% or less. The resistivity of this electrode is 1×10 -2 Ωcm or less is preferable.

[0193] The light-emitting device shown in FIG. 1E has a buffer layer 109 on the second electrode 102. Examples of the buffer layer 109 include an organic film, a semiconductor film, and an inorganic insulating film. The light-emitting device shown in FIG. 1E is configured to extract light emitted from the EL layer 103 to the buffer layer 109 side. Therefore, the buffer layer 109 preferably has a function of transmitting visible light or near-infrared light. This suppresses light absorption by the buffer layer 109 and improves the light extraction efficiency of the light-emitting device. Examples of the organic film include layers containing a material with high hole injection properties, a material with high hole transport properties, a hole blocking material, a material with high electron transport properties, a material with high electron injection properties, an electron blocking material, or a bipolar material, which can be used in light-emitting devices. Examples of the semiconductor film include a semiconductor film that transmits visible light or near-infrared light. Examples of the inorganic insulating film include a silicon nitride film. The buffer layer 109 preferably has a passivation function. This suppresses the intrusion of impurities such as moisture into the light-emitting device. Furthermore, when the second electrode 102 has a function of reflecting visible light or near-infrared light, the buffer layer 109 can reduce the loss of light energy due to surface plasmons in the second electrode 102.

[0194] <Specific structure of the light-emitting device> Next, a specific structure of the light-emitting device will be described, using a light-emitting device having a single structure as shown in Figure 1B.

[0195] <Electrode> As materials for forming the first electrode 101 and the second electrode 102, as long as the above-mentioned functions of both electrodes are satisfied, the following materials can be used in appropriate combination. For example, metals, alloys, electrically conductive compounds, and mixtures thereof can be used appropriately. Specific examples include In-Sn oxide (also called ITO), In-Si-Sn oxide (also called ITSO), In-Zn oxide, and In-W-Zn oxide. Other metals that can be used include aluminum (Al), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), gallium (Ga), zinc (Zn), indium (In), tin (Sn), molybdenum (Mo), tantalum (Ta), tungsten (W), palladium (Pd), gold (Au), platinum (Pt), silver (Ag), yttrium (Y), and neodymium (Nd), as well as alloys containing appropriate combinations of these metals (such as an alloy of silver, palladium, and copper (Ag-Pd-Cu(APC))). Other examples that can be used include elements belonging to Group 1 or 2 of the periodic table (e.g., lithium (Li), cesium (Cs), calcium (Ca), and strontium (Sr)) that are not listed above, rare earth metals such as europium (Eu) and ytterbium (Yb), and alloys containing appropriate combinations of these, graphene, and the like.

[0196] When a light-emitting device having a microcavity structure is fabricated, the first electrode 101 is formed as a reflective electrode, and the second electrode 102 is formed as a semi-transmissive and semi-reflective electrode. Therefore, a single or multiple desired conductive materials can be used to form a single layer or a laminated layer. The second electrode 102 is formed after the EL layer 103 is formed, by selecting a material in the same manner as above. These electrodes can be fabricated by sputtering, vacuum deposition, or the like.

[0197] <Hole injection layer> The hole injection layer 111 is a layer that injects holes from the first electrode 101, which is an anode, to the EL layer 103, and is a layer that contains a material with high hole injection properties.

[0198] A composite material containing a hole-transporting material and an acceptor material (electron-accepting material) can be used as a material with high hole-injection properties. In this case, electrons are extracted from the hole-transporting material by the acceptor material, generating holes in the hole-injection layer 111, which are then injected into the light-emitting layer 113 via the hole-transporting layer. The hole-injection layer 111 may be formed as a single layer made of a composite material containing a hole-transporting material and an acceptor material, or may be formed by laminating the hole-transporting material and the acceptor material as separate layers.

[0199] The hole injection layer 111 is preferably made of a composite material of a first organic compound and a second organic compound.

[0200] Other materials with high hole injection properties that can be used include transition metal oxides such as molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, and manganese oxide, and phthalocyanine compounds such as phthalocyanine (abbreviated as HPc) and copper phthalocyanine (abbreviated as CuPc).

[0201] Materials with high hole injection properties include 4,4',4''-tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA), 4,4',4''-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (abbreviation: MTDATA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), 4,4'-bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviation: DNTPD), and 1,3,5-tris[ Aromatic amine compounds such as N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B), 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), and 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1) can be used.

[0202] Examples of materials with high hole injection properties include 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). Alternatively, polymer compounds with added acids, such as poly(3,4-ethylenedioxythiophene) / poly(styrenesulfonic acid) (abbreviation: PEDOT / PSS) and polyaniline / poly(styrenesulfonic acid) (PAni / PSS), can also be used.

[0203] Alternatively, the hole transporting material used in the hole injection layer 111 may have at least one of a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton. The hole transporting material 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 atom of the amine via an arylene group.

[0204] Examples of hole transporting materials 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-8-yl, Ran-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-(2;1'-binaphthyl-6-yl)-4',4''-diphenyltriphenylamine (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-(6;2'-binaphthyl-2-yl)-4',4''-diphenyltriphenylamine (abbreviation: BBA(βN2)B), 4-(2;2'-binaphthyl-7-yl)-4',4''-diphenyltriphenylamine (abbreviation: BBA(βN2)B-03), 4-(1;2'-binaphthyl-4-yl)-4',4''-diphenyltriphenylamine (abbreviation: BBAβNαNB), 4-(1;2'-binaphthyl-5-yl)-4',4''-Diphenyltriphenylamine (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-(1-naphthyl)-4'-phenyltriphenylamine (abbreviation: αNBA1BP), 4,4'-bis(1-naphthyl)triphenylamine (abbreviation: αNBB1BP), 4,4'-diphenyl-4''-[4'-(carbazol-9-yl)biphenyl-4-yl]triphenylamine (abbreviation: YGTBi1BP), 4'-[4-(3-phenyl-9H-carbazol-9-yl)phenyl]tris(1,1'-biphenyl-4- yl)amine (abbreviation: YGTBi1BP-02), 4-[4'-(carbazol-9-yl)biphenyl-4-yl]-4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: YGTBiβNB), 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([1,1'-biphenyl]- 4-yl)-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-(9,9-Dimethyl-9H-fluoren-2-yl)dibenzofuran-4-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-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-phenyl-4'-[4-(9-phenylfluoren-9-yl)phenyl]triphenylamine (abbreviation: BPAFLBi), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl- Examples include 4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBiBP), 4-(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]spiro-9,9'-bifluoren-2-amine (abbreviation: PCBASF), and N-(1,1'-biphenyl-4-yl)-9,9-dimethyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9H-fluoren-2-amine (abbreviation: PCBBiF).

[0205] Acceptor materials that can be used for the hole injection layer 111 include chloranil and 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT-CN).

[0206] In addition, oxides of metals belonging to Groups 4 to 8 of the periodic table can also be used as acceptor materials. Specific examples include molybdenum oxide, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, tungsten oxide, manganese oxide, and rhenium oxide. Among these, molybdenum oxide is particularly preferred because it is stable in the air, has low hygroscopicity, and is easy to handle. Organic acceptors such as quinodimethane derivatives, chloranil derivatives, and hexaazatriphenylene derivatives can also be used.

[0207] <Hole transport layer> The first hole transport layer 112a is a layer that transports holes injected from the first electrode 101 by the hole injection layer 111 to the light emitting layer 113, and is a layer that contains a hole transport material.

[0208] The hole transporting material used for the first hole transporting layer 112 a preferably has a HOMO level that is the same as or close to the HOMO level of the hole injection layer 111 .

[0209] The hole transport material used for the first hole transport layer 112a is 10 -6 cm 2 A substance having a hole mobility of / Vs or more is preferred. Note that other substances can also be used as long as they have a higher hole transporting property than electron transporting property.

[0210] The first hole transport layer 112a includes a first organic compound (hole transport material).

[0211] When the same first organic compound is used for both the hole injection layer 111 and the first hole transport layer 112a, the refractive index difference can be reduced and the light extraction efficiency can be increased.

[0212] The light-emitting device of one embodiment of the present invention includes a buffer layer 119 between the first hole-transport layer 112a and the light-emitting layer 113. The buffer layer 119 includes a second organic compound. The buffer layer 119 may further include a third organic compound (a hole-transport material having an electron-blocking property).

[0213] The light-emitting device of one embodiment of the present invention preferably further includes a second hole-transport layer 112b between the buffer layer 119 and the light-emitting layer 113. The second hole-transport layer 112b preferably functions as an electron blocking layer. The second hole-transport layer 112b preferably includes a third organic compound (a hole-transport material having an electron blocking property). The second hole-transport layer 112b may further include a second organic compound.

[0214] The first hole-transport layer 112a, the buffer layer 119, and the second hole-transport layer 112b can each be formed using the same hole-transporting material as can be used for the hole-injection layer 111.

[0215] Other preferred hole transporting materials include materials with high hole transporting properties, such as π-electron-rich heteroaromatic compounds (for example, carbazole derivatives, thiophene derivatives, furan derivatives, etc.) and aromatic amines (compounds having an aromatic amine skeleton).

[0216] Examples of carbazole derivatives (compounds having a carbazole skeleton) include bicarbazole derivatives (for example, 3,3'-bicarbazole derivatives) and aromatic amines having a carbazolyl group.

[0217] Specific examples of bicarbazole derivatives (for example, 3,3′-bicarbazole derivatives) include 3,3′-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), 9,9′-bis(1,1′-biphenyl-4-yl)-3,3′-bi-9H-carbazole, 9,9′-bis(1,1′-biphenyl-3-yl)-3,3′-bi-9H-carbazole, 9-(1,1′-biphenyl-3-yl)-9′-(1,1′-biphenyl-4-yl)-9H,9′H-3,3′-bicarbazole (abbreviation: mBPCCBP), and 9-(2-naphthyl)-9′-phenyl-9H,9′H-3,3′-bicarbazole (abbreviation: βNCCP).

[0218] Specific examples of aromatic amines having a carbazolyl group include N-(4-biphenyl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9-phenyl-9H-carbazol-3-amine (abbreviation: PCBiF), 4-phenyldiphenyl-(9-phenyl-9H-carbazol-3-yl)amine (abbreviation: PCA1BP), N,N'-bis(9-phenylcarbazol-3-yl)-N,N'-diphenylbenzene-1,3-diamine (abbreviation: PCA1BP), and N,N'-bis(9-phenylcarbazol-3-yl)-N,N'-diphenylbenzene-1,3-diamine (abbreviation: PCA1BP). : PCA2B), N,N',N''-triphenyl-N,N',N''-tris(9-phenylcarbazol-3-yl)benzene-1,3,5-triamine (abbreviation: PCA3B), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), PCzPCA1, PCzPCA2, PCzPCN1, 3-[N-(4-diphenylaminophenyl)-N-phenyl] 3,6-bis[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA1), 3,6-bis[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA2), 3,6-bis[N-(4-diphenylaminophenyl)-N-(1-naphthyl)amino]-9-phenylcarbazole (abbreviation: PCzTPN2), 2-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]spiro-9,9' -bifluorene (abbreviation: PCASF), N-[4-(9H-carbazol-9-yl)phenyl]-N-(4-phenyl)phenylaniline (abbreviation: YGA1BP), N,N'-bis[4-(carbazol-9-yl)phenyl]-N,N'-diphenyl-9,9-dimethylfluorene-2,7-diamine (abbreviation: YGA2F), and 4,4',4''-tris(carbazol-9-yl)triphenylamine (abbreviation: TCTA).

[0219] In addition to the above, examples of the carbazole derivatives include 3-[4-(9-phenanthryl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPPn), 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 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), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB), and 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: CzPA).

[0220] Specific examples of thiophene derivatives (compounds having a thiophene skeleton) and furan derivatives (compounds having a furan skeleton) include compounds having a thiophene skeleton such as 4,4′,4″-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,8-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), as well 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).

[0221] Specific examples of aromatic amines include 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB or α-NPD), 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 (abbreviated as BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviated as mBPAFLP), N-(9,9-dimethyl-9H-fluoren-2-yl)-N-{9,9-dimethyl-2-[N'-phenyl-N'-(9,9-dimethyl-9H-fluoren-2-yl) )amino]-9H-fluoren-7-yl}phenylamine (abbreviation: DFLADFL), N-(9,9-dimethyl-2-diphenylamino-9H-fluoren-7-yl)diphenylamine (abbreviation: DPNF), 2-[N-(4-diphenylaminophenyl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: DPASF), 2,7-bis[N-(4-diphenylaminophenyl)-N- phenylamino]spiro-9,9'-bifluorene (abbreviation: DPA2SF), 4,4',4''-tris[N-(1-naphthyl)-N-phenylamino]triphenylamine (abbreviation: 1'-TNATA), TDATA, m-MTDATA, N,N'-di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), DPAB, DNTPD, and DPA3B.

[0222] As the hole transporting material, polymer compounds such as PVK, PVTPA, PTPDMA, and Poly-TPD can also be used.

[0223] The hole transport material is not limited to the above, and one or more of various known materials can be used in combination for the hole injection layer 111, the first hole transport layer 112a, the buffer layer 119, and the second hole transport layer 112b.

[0224] In the light-emitting device of one embodiment of the present invention, the HOMO level of the hole-transport material used in the first hole-transport layer 112a is preferably lower than or equal to the HOMO level of the hole-transport material used in the hole-injection layer 111. The difference between the HOMO level of the hole-transport material used in the first hole-transport layer 112a and the HOMO level of the hole-transport material used in the hole-injection layer 111 is preferably within 0.2 eV. It is more preferable that the hole-transport material used in the hole-injection layer 111 and the hole-transport material used in the first hole-transport layer 112a are the same because this allows smooth hole injection.

[0225] The HOMO level of the hole-transporting material (third organic compound) used in the second hole-transporting layer 112b is preferably lower (deeper) than the HOMO level of the hole-transporting material (first organic compound) used in the first hole-transporting layer 112a. Furthermore, the difference in the HOMO levels of the two hole-transporting materials is preferably within 0.2 eV. The above-described relationship among the HOMO levels of the hole-transporting materials used in the hole-injection layer 111, the first hole-transporting layer 112a, and the second hole-transporting layer 112b allows smooth hole injection into each layer, preventing an increase in driving voltage and a deficiency of holes in the light-emitting layer 113.

[0226] The hole-transporting material (third organic compound) used for the second hole-transporting layer 112b preferably has a hole-transporting skeleton, such as a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, or an anthracene skeleton, which does not make the HOMO level of the hole-transporting material too high.

[0227] <Light-emitting layer> The light-emitting layer 113 is a layer containing a light-emitting substance. The light-emitting layer 113 can contain one or more types of light-emitting substances. As the light-emitting substance, a substance that emits light of a color such as blue, purple, blue-purple, green, yellow-green, yellow, orange, or red is appropriately used. Furthermore, a substance that emits near-infrared light can also be used as the light-emitting substance. Furthermore, by using different light-emitting substances in the multiple light-emitting layers, a configuration that emits different light colors (for example, white light obtained by combining light-emitting colors that are complementary colors) can be achieved. Furthermore, one light-emitting layer may contain different light-emitting substances.

[0228] The light-emitting layer 113 preferably contains one or more organic compounds (host materials, assist materials, etc.) in addition to a light-emitting substance (guest material). One or both of a hole-transporting material and an electron-transporting material described in this embodiment can be used as the one or more organic compounds. Alternatively, a bipolar material may be used as the one or more organic compounds.

[0229] The light-emitting substance that can be used in the light-emitting layer 113 is not particularly limited, and a light-emitting substance that converts singlet excitation energy into light emission in the visible light region or near-infrared light region, or a light-emitting substance that converts triplet excitation energy into light emission in the visible light region or near-infrared light region can be used.

[0230] Examples of luminescent substances that convert singlet excitation energy into luminescence include fluorescent substances (fluorescent materials), such as pyrene derivatives, anthracene derivatives, triphenylene derivatives, fluorene derivatives, carbazole derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, dibenzoquinoxaline derivatives, quinoxaline derivatives, pyridine derivatives, pyrimidine derivatives, phenanthrene derivatives, naphthalene derivatives, etc. Pyrene derivatives are particularly preferred because of their high luminescence quantum yield. Specific examples of pyrene derivatives include N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-bis(dibenzofuran-2-yl)-N,N'-diphenylpyrene-1,6-diamine (abbreviation: 1,6FrAPrn), and N,N'-bis(dibenzothiophen-2-yl)-N,N' -diphenylpyrene-1,6-diamine (abbreviation: 1,6ThAPrn), N,N'-(pyrene-1,6-diyl)bis[(N-phenylbenzo[b]naphtho[1,2-d]furan)-6-amine] (abbreviation: 1,6BnfAPrn), N,N'-(pyrene-1,6-diyl)bis[(N-phenylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-02), and N,N'-(pyrene-1,6-diyl)bis[(6,N-diphenylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-03).

[0231] Other compounds include 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'-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: Y GAPA), 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviated as 2YGAPPA), N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviated as PCAPA), 4-(10-phenyl-9-anthryl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBAPA), 4-[4-(10-phenyl-9-anthryl)phenyl]-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine N,N'-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene)bis[N,N',N'-triphenyl-1,4-phenylenediamine] (abbreviation: DPABPA), N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: 2PCAPPA), N-[4-(9,10-diphenyl- Examples of compounds that can be used include [N-(9-phenyl-9H-carbazol-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10PCA2Nbf(IV)-02), and 3,10-bis[N-(dibenzofuran-3-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10FrA2Nbf(IV)-02).

[0232] Furthermore, examples of light-emitting substances that convert triplet excitation energy into luminescence include phosphorescent substances (phosphorescent materials) and thermally activated delayed fluorescence (TADF) materials that exhibit thermally activated delayed fluorescence.

[0233] Examples of phosphorescent materials include organometallic complexes, metal complexes (platinum complexes), and rare earth metal complexes. These materials emit different luminescent colors (emission peaks), so they can be appropriately selected and used as needed.

[0234] Examples of phosphorescent materials that exhibit blue or green and have an emission spectrum with a peak wavelength of 450 nm or more and 570 nm or less include the following substances.

[0235] For example, tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN2]phenyl-κC}iridium(III) (abbreviation: [Ir(mpptz-dmp)3]), tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Mptz)3]), tris[4-(3-biphenyl organometallic complexes with a 4H-triazole skeleton, such as tris[3-(5-biphenyl)-5-isopropyl-4-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(iPrptz-3b)3]), tris[3-(5-biphenyl)-5-isopropyl-4-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: Ir(iPr5btz)3]), organometallic complexes with a 1H-triazole skeleton, such as fac-tris[1-(2,6-diisopropylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(Mptz1-mp)3]), tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Prptz1-Me)3]); organometallic complexes with an imidazole skeleton, such as tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: [Ir(iPrpmi)3]), 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)]) and bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’] Organometallic complexes with a phenylpyridine derivative having an electron-withdrawing group as a ligand, such as iridium(III) acetylacetonate (abbreviation: FIr(acac)), are also included.

[0236] Examples of phosphorescent materials that exhibit green or yellow and have an emission spectrum with a peak wavelength of 495 nm or more and 590 nm or less include the following substances.

[0237] For example, 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(mppm)2(acac)]), (acetylacetonato)bis[6-(2-norbornyl)-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-(2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(mpmppm) 2(acac)]), (acetylacetonato)bis{4,6-dimethyl-2-[6-(2,6-dimethylphenyl)-4-pyrimidinyl-κN3]phenyl-κC}iridium(III) (abbreviation: [Ir(dmppm-dmp)2(acac)]), and (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm)2(acac)]). iridium complexes, 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)]), 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’ Organometallic iridium complexes with a pyridine skeleton, such as iridium(III) acetylacetonate (abbreviation: [Ir(pq)2(acac)]), [2-(4-phenyl-2-pyridinyl-κN)phenyl-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: [Ir(ppy)2(4dppy)]), bis[2-(2-pyridinyl-κN)phenyl-κC][2-(4-methyl-5-phenyl-2-pyridinyl-κN)phenyl-κC], and bis(2,4-diphenyl-1,3-oxazolato-N,C) 2’ ) Iridium(III) acetylacetonate (abbreviation: [Ir(dpo)2(acac)]), bis{2-[4'-(perfluorophenyl)phenyl]pyridinato-N,C 2’}Iridium(III) acetylacetonate (abbreviation: [Ir(p-PF-ph)2(acac)]), bis(2-phenylbenzothiazolato-N,C 2’ ) iridium(III) acetylacetonate (abbreviated as [Ir(bt)2(acac)]), as well as rare earth metal complexes such as tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviated as [Tb(acac)3(Phen)]).

[0238] Examples of phosphorescent materials that exhibit yellow or red and have an emission spectrum with a peak wavelength of 570 nm or more and 750 nm or less include the following substances.

[0239] For example, (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)]), bis[4,6-di(naphthalen-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(d1npm)2(dpm)]), tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) Organometallic complexes with pyrimidine skeletons 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 bis{4,6-dimethyl-2-[3-(3,5-dimethylphenyl)-5-phenyl-2-pyrazinyl-κN]phenyl-κC}(2,6-dimethyl-3,5-heptanedionato-κC). 2 O,O')iridium(III) (abbreviation: [Ir(dmdppr-P)2(dibm)]), bis{4,6-dimethyl-2-[5-(4-cyano-2,6-dimethylphenyl)-3-(3,5-dimethylphenyl)-2-pyrazinyl-κN]phenyl-κC}(2,2,6,6-tetramethyl-3,5-heptanedionato-κ) 2 O,O')iridium(III) (abbreviation: [Ir(dmdppr-dmCP)2(dpm)]), (acetylacetonato)bis[2-methyl-3-phenylquinoxalinato-N,C 2’ ]iridium(III) (abbreviation: [Ir(mpq)2(acac)]), (acetylacetonato)bis(2,3-diphenylquinoxalinato-N,C 2’) Iridium(III) (abbreviation: [Ir(dpq)2(acac)]), (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: [Ir(Fdpq)2(acac)]), bis{4,6-dimethyl-2-[5-(5-cyano-2-methylphenyl)-3-(3,5-dimethylphenyl)-2-pyrazinyl-κN]phenyl-κC}(2,2,6,6-tetramethyl-3,5-heptanedionato-κN) 2 Organometallic complexes with pyrazine skeletons, such as tris(1-phenylisoquinolinato-N,C)iridium(III) (abbreviation: [Ir(dmdppr-mCP)(dpm)]), 2’ ) Iridium(III) (abbreviation: [Ir(piq)3]), bis(1-phenylisoquinolinato-N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: [Ir(piq)2(acac)]), bis[4,6-dimethyl-2-(2-quinolinyl-κN)phenyl-κC](2,4-pentanedionato-κ 2 These include organometallic complexes with a pyridine skeleton, such as (O,O')iridium(III), platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrinplatinum(II) (abbreviation: [PtOEP]), and rare earth metal complexes such as tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III) (abbreviation: [Eu(DBM)3(Phen)]) and tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III) (abbreviation: [Eu(TTA)3(Phen)]).

[0240] As the organic compound (host material, assist material, etc.) used in the light-emitting layer 113, one or more substances having an energy gap larger than the energy gap of the light-emitting substance can be selected and used.

[0241] When the light-emitting substance used in the light-emitting layer 113 is a fluorescent material, an organic compound that has a high energy level in a singlet excited state and a low energy level in a triplet excited state is preferably used as the organic compound used in combination with the light-emitting substance.

[0242] Although some of the examples overlap with the above examples, specific examples of organic compounds are shown below from the viewpoint of preferable combinations with light-emitting substances (fluorescent materials, phosphorescent materials).

[0243] When the luminescent substance is a fluorescent material, examples of organic compounds that can be used in combination with the luminescent substance include condensed polycyclic aromatic compounds such as anthracene derivatives, tetracene derivatives, phenanthrene derivatives, pyrene derivatives, chrysene derivatives, and dibenzo[g,p]chrysene derivatives.

[0244] Specific examples of organic compounds (host materials) used in combination with fluorescent materials include 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), 3,6-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: DPCzPA), PCPN, 9,10-diphenylanthracene (abbreviation: DPAnth), N,N-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: CzA1PA), ), 4-(10-phenyl-9-anthryl)triphenylamine (abbreviation: DPhPA), 4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), N,9-diphenyl-N-{4-[4-(10-phenyl-9-anthryl)phenyl]phenyl}-9H-carbazol-3-amine (abbreviation: PCAPBA), N-(9,10-diphenyl N,N,N',N',N'',N'',N''',N'''-Octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), CzPA, 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA), 6-[3-(9,10-diphenyl-2-anthryl)phenyl] 1,2-diphenyl-4'-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), 9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA), 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 9,9'-bianthryl (abbreviation: BANT), 9,9'-(stilbene-3,Examples include 3'-diyl)diphenanthrene (abbreviation: DPNS), 9,9'-(stilbene-4,4'-diyl)diphenanthrene (abbreviation: DPNS2), 1,3,5-tri(1-pyrenyl)benzene (abbreviation: TPB3), 5,12-diphenyltetracene, and 5,12-bis(biphenyl-2-yl)tetracene.

[0245] When the light-emitting substance is a phosphorescent material, an organic compound having a triplet excitation energy greater than the triplet excitation energy (energy difference between the ground state and the triplet excited state) of the light-emitting substance can be selected as the organic compound to be used in combination with the light-emitting substance.

[0246] When a plurality of organic compounds (e.g., a first host material and a second host material (or assist material)) are used in combination with a light-emitting substance to form an exciplex, it is preferable to use these plurality of organic compounds in combination with a phosphorescent material (particularly an organometallic complex).

[0247] With this structure, light emission can be efficiently obtained using Exciplex-Triplet Energy Transfer (ExTET), which is energy transfer from an exciplex to a light-emitting substance. It is preferable to combine a plurality of organic compounds that easily form an exciplex, and it is particularly preferable to combine a compound that easily accepts holes (hole transport material) with a compound that easily accepts electrons (electron transport material). Specific examples of the hole transport material and the electron transport material include the materials described in this embodiment. This structure simultaneously achieves high efficiency, low-voltage operation, and a long life for the light-emitting device.

[0248] When the luminescent substance is a phosphorescent material, examples of organic compounds that can be used in combination with the luminescent substance include aromatic amines, carbazole derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, zinc-based metal complexes, aluminum-based metal complexes, oxadiazole derivatives, triazole derivatives, benzimidazole derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, pyrimidine derivatives, triazine derivatives, pyridine derivatives, bipyridine derivatives, and phenanthroline derivatives.

[0249] Among the above, specific examples of the aromatic amines (compounds having an aromatic amine skeleton), carbazole derivatives, dibenzothiophene derivatives (thiophene derivatives), and dibenzofuran derivatives (furan derivatives), which are organic compounds with high hole-transporting properties, are the same as the specific examples of the hole-transporting materials shown above.

[0250] Specific examples of zinc-based metal complexes and aluminum-based metal complexes, which are organic compounds with high electron-transporting properties, include metal complexes having a quinoline skeleton or a benzoquinoline skeleton, such as tris(8-quinolinolato)aluminum(III) (abbreviation: Alq), tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviation: Almq3), bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq2), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (abbreviation: BAlq), and bis(8-quinolinolato)zinc(II) (abbreviation: Znq).

[0251] In addition, metal complexes having oxazole or thiazole ligands, such as bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO) and bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ), can also be used.

[0252] Specific examples of organic compounds with high electron transport properties, such as oxadiazole derivatives, triazole derivatives, benzimidazole derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, and phenanthroline derivatives, include 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-8), and 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-9). [4-(4-biphenylyl)phenyl]-9H-carbazole (abbreviation: CO11), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1,2,4-triazole (abbreviation: p-EtTAZ), 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophene) mDBTBIm-II), 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOs), bathophenanthroline (abbreviation: BPhen), bathocuproine (abbreviation: BCP), 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBPhen), 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDB q-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviated as 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviated as 2mCzBPDBq), 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as 7mDBTPDBq-II), and 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as 6mDBTPDBq-II).

[0253] Specific examples of organic compounds with high electron transport properties, such as heterocyclic compounds having a diazine skeleton, heterocyclic compounds having a triazine skeleton, and heterocyclic compounds having a pyridine skeleton, include 4,6-bis[3-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), and 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II). ]pyrimidine (abbreviation: 4,6mCzP2Pm), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), 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(9H-fluoren)-2-yl]-1,3,5-triazine (abbreviation: BP-SFTzn), 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-8-yl)phenyl]phenyl}-4,6-diphenyl-1, Examples include 3,5-triazine (abbreviation: mBnfBPTzn), 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-6-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn-02), 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy), and 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB).

[0254] As organic compounds with high electron transport properties, polymer compounds such as poly(2,5-pyridinediyl) (abbreviation: PPy), poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)] (abbreviation: PF-Py), and poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2'-bipyridine-6,6'-diyl)] (abbreviation: PF-BPy) can also be used.

[0255] TADF materials are materials that can upconvert (reverse intersystem crossing) a triplet excited state to a singlet excited state with a small amount of thermal energy, and efficiently emit light (fluorescence) from the singlet excited state. The conditions for efficiently obtaining thermally activated delayed fluorescence include an energy difference between the triplet excited level and the singlet excited level of 0 eV or more and 0.2 eV or less, preferably 0 eV or more and 0.1 eV or less. The delayed fluorescence in TADF materials refers to light emission that has a spectrum similar to that of normal fluorescence but has a significantly long lifetime. The lifetime is approximately 10 -6 seconds or more, preferably 10 -3 More than a second.

[0256] Examples of TADF materials include fullerene and its derivatives, acridine derivatives such as proflavine, eosin, etc. Also included are metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), palladium (Pd), etc. Examples of metal-containing porphyrins include protoporphyrin-tin fluoride complex (abbreviation: SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (abbreviation: SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (abbreviation: SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (abbreviation: SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (abbreviation: SnF2(OEP)), etioporphyrin-tin fluoride complex (abbreviation: SnF2(Etio I)), and octaethylporphyrin-platinum chloride complex (abbreviation: PtCl2OEP).

[0257] Other examples include 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviated as PIC-TRZ), PCCzPTzn, 2-[4-(10H-phenoxazin-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviated as PXZ-TRZ), 3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviated as PXZ-TRZ), and Heterocyclic compounds having a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring can be used, such as 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). Substances in which a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded are particularly preferred because the donor properties of the π-electron-rich heteroaromatic ring and the acceptor properties of the π-electron-deficient heteroaromatic ring are both enhanced, resulting in a smaller energy difference between the singlet excited state and the triplet excited state.

[0258] When a TADF material is used, it can be used in combination with other organic compounds, particularly the host material, hole transport material, and electron transport material described above.

[0259] Furthermore, the above materials can be used in combination with low-molecular-weight or high-molecular-weight materials to form the light-emitting layer 113. For film formation, known methods (such as vapor deposition, coating, and printing) can be used as appropriate.

[0260] <Electron transport layer> The electron transport layer 114 is a layer that transports electrons injected from the second electrode 102 by the electron injection layer 115 to the light-emitting layer 113. The electron transport layer 114 is a layer that contains an electron transporting material. The electron transporting material used for the electron transport layer 114 is 1×10 -6 cm 2 A substance having an electron mobility of 1 / Vs or more is preferred. Note that other substances can also be used as long as they have a higher electron transporting property than a hole transporting property.

[0261] Examples of the electron-transporting material that can be used include metal complexes having a quinoline skeleton, metal complexes having a benzoquinoline skeleton, metal complexes having an oxazole skeleton, and metal complexes having a thiazole skeleton, as well as materials with high electron-transporting properties, such as oxadiazole derivatives, triazole derivatives, imidazole derivatives, oxazole derivatives, thiazole derivatives, phenanthroline derivatives, quinoline derivatives having a quinoline ligand, benzoquinoline derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, and π-electron-deficient heteroaromatic compounds including nitrogen-containing heteroaromatic compounds.

[0262] As specific examples of the electron transporting material, the materials shown above can be used.

[0263] In the light-emitting device of one embodiment of the present invention, the electron-transport layer 114 preferably contains an electron-transporting material and an organometallic complex of an alkali metal or an alkaline earth metal.

[0264] In this case, the electron transporting material preferably has an anthracene skeleton, more preferably an anthracene skeleton and a heterocyclic skeleton. The heterocyclic skeleton is preferably a nitrogen-containing five-membered ring skeleton. The nitrogen-containing five-membered ring skeleton is particularly preferably a nitrogen-containing five-membered ring skeleton containing two heteroatoms in the ring, such as a pyrazole ring, an imidazole ring, an oxazole ring, or a thiazole ring.

[0265] As the organometallic complex of an alkali metal or alkaline earth metal, an organic complex of lithium is preferred, and 8-quinolinolato-lithium (abbreviation: Liq) is particularly preferred.

[0266] By reducing the electron transportability in the electron transport layer 114, it is possible to control the amount of electrons injected into the light-emitting layer 113, and prevent the light-emitting layer 113 from becoming an electron-excess state. In addition, by widening the light-emitting region in the light-emitting layer 113 and distributing the load on the materials that make up the light-emitting layer 113, it is possible to provide a light-emitting device with a long life and high light-emitting efficiency.

[0267] Furthermore, it is preferable that the electron transport layer 114 has a portion with a different mixture ratio between the electron transport material and the organometallic complex of an alkali metal or alkaline earth metal in the thickness direction thereof. The electron transport layer 114 may have a concentration gradient or may have a stacked structure of multiple layers with different mixture ratios between the electron transport material and the organometallic complex of an alkali metal or alkaline earth metal.

[0268] The magnitude of the mixing ratio can be estimated from the detected amount of atoms or molecules obtained by time-of-flight secondary ion mass spectrometry (ToF-SIMS). In parts composed of the same two types of materials but with different mixing ratios, the magnitude of the values ​​detected by ToF-SIMS analysis corresponds to the abundance of the atoms or molecules of interest. Therefore, by comparing the detected amounts of the electron transport material and the organometallic complex, the magnitude of the mixing ratio can be estimated.

[0269] The content of the organometallic complex in the electron transport layer 114 is preferably lower on the second electrode 102 side than on the first electrode 101 side. That is, the electron transport layer 114 is preferably formed so that the concentration of the organometallic complex increases from the second electrode 102 side toward the first electrode 101 side. That is, the electron transport layer 114 has a portion on the light-emitting layer 113 side where the electron transport material is present in a smaller amount than a portion on the light-emitting layer 113 side where the electron transport material is present in a larger amount. In other words, the electron transport layer 114 has a portion on the light-emitting layer 113 side where the organometallic complex is present in a larger amount than a portion on the light-emitting layer 113 side where the organometallic complex is present in a smaller amount.

[0270] A change in the carrier balance in the light-emitting device of one embodiment of the present invention is believed to be caused by a change in the electron mobility of the electron-transport layer 114. In the light-emitting device of one embodiment of the present invention, a concentration difference of an organometallic complex of an alkali metal or alkaline earth metal exists inside the electron-transport layer 114. The electron-transport layer 114 has a region where the concentration of the organometallic complex is high between a region where the concentration of the organometallic complex is low and the light-emitting layer 113. That is, the region where the concentration of the organometallic complex is low is located closer to the second electrode 102 than the region where the concentration of the organometallic complex is high. The higher the concentration of the organometallic complex, the higher the electron mobility of the electron-transport layer 114; therefore, the electron mobility of the electron-transport layer 114 is determined by the region where the concentration is low.

[0271] When the light-emitting device is driven by applying a voltage, the organometallic complex of the alkali metal or alkaline earth metal diffuses from the first electrode 101 side to the second electrode 102 side (from the region of high concentration to the region of low concentration) due to the voltage. The region of high concentration of the organometallic complex is located closer to the first electrode 101 than the region of low concentration, and as a result, the electron mobility of the electron transport layer 114 improves with driving. This causes a change in the carrier balance inside the light-emitting device, shifting the recombination region and resulting in a light-emitting device with a long life.

[0272] The light-emitting device according to one embodiment of the present invention having the above-described configuration has an extremely long lifetime, and in particular, the lifetime can be significantly extended in a range where degradation is extremely small up to about LT95 (the time it takes for the luminance to decrease to 95% of the initial luminance).

[0273] <Electron injection layer> The electron injection layer 115 is a layer containing a material with high electron injection properties. The electron injection layer 115 may contain any of Liq, lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF), lithium oxide (LiO x ) or an alkaline earth metal, or a compound thereof, can be used. Also, a rare earth metal compound such as erbium fluoride (ErF3) can be used. Furthermore, an electride can be used for the electron injection layer 115. For example, an electride can be a substance in which a mixed oxide of calcium and aluminum is doped with electrons at a high concentration. Note that the above-mentioned substance constituting the electron transport layer 114 can also be used.

[0274] The electron-injection layer 115 may also be formed using a composite material containing an electron-transporting material and a donor material (electron-donating material). Such a composite material has excellent electron-injecting and electron-transporting properties because electrons are generated in the organic compound by the electron donor. In this case, the organic compound is preferably a material that is excellent in transporting the generated electrons. Specifically, the electron-transporting materials (metal complexes, heteroaromatic compounds, etc.) used in the electron-transporting layer 114 described above can be used. The electron donor may be any substance that exhibits electron-donating properties to the organic compound. Specifically, alkali metals, alkaline earth metals, and rare earth metals are preferred, such as lithium, cesium, magnesium, calcium, erbium, and ytterbium. Alkali metal oxides and alkaline earth metal oxides are preferred, such as lithium oxide, calcium oxide, and barium oxide. A Lewis base such as magnesium oxide can also be used. An organic compound such as tetrathiafulvalene (TTF) can also be used.

[0275] <Charge generation layer> In the light-emitting device shown in FIG. 1C, the charge generation layer 104 has the function of injecting electrons into the EL layer 103a and injecting holes into the EL layer 103b when a voltage is applied between the first electrode 101 (anode) and the second electrode 102 (cathode).

[0276] The charge generation layer 104 may be configured to contain a hole transport material and an acceptor material (electron acceptor material), or may be configured to contain an electron transport material and a donor material. By forming the charge generation layer 104 with such a configuration, it is possible to suppress an increase in driving voltage when an EL layer is stacked.

[0277] The charge generation layer 104 can be formed using a composite material of a first organic compound and a second organic compound.

[0278] In addition, the materials described above can also be used as the hole transporting material, the acceptor material, the electron transporting material, and the donor material.

[0279] The light-emitting device described in this embodiment can be fabricated by a vacuum process such as vapor deposition, a solution process such as spin coating, or an inkjet method. When a vapor deposition method is used, a physical vapor deposition (PVD) method such as sputtering, ion plating, ion beam deposition, molecular beam deposition, or vacuum deposition, or a chemical vapor deposition (CVD) method can be used. In particular, the functional layers (hole injection layer, hole transport layer, light-emitting layer, electron transport layer, and electron injection layer) and the charge generation layer included in the EL layer can be formed by a vapor deposition method (vacuum deposition, etc.), a coating method (dip coating, die coating, bar coating, spin coating, spray coating, etc.), a printing method (inkjet printing, screen printing, offset printing, flexography, gravure printing, microcontact printing, etc.), or the like.

[0280] The materials of the functional layer and charge generating layer constituting the EL layer 103 are not limited to the above-mentioned materials. For example, the functional layer may be made of a polymer compound (oligomer, dendrimer, polymer, etc.), a medium molecular weight compound (a compound in the intermediate range between a low molecular weight and a high molecular weight: molecular weight of 400 to 4000), an inorganic compound (quantum dot material, etc.), etc. The quantum dot material may be a colloidal quantum dot material, an alloy quantum dot material, a core-shell quantum dot material, a core quantum dot material, etc.

[0281] As described above, the light-emitting device of this embodiment uses a hole-transporting material with a low refractive index for the first layer. Furthermore, a layer containing a material with a high electron-accepting property relative to the hole-transporting material is provided as a second layer on the first layer. This allows for a light-emitting device with high luminous efficiency and low driving voltage to be obtained.

[0282] This embodiment mode can be combined with other embodiment modes as appropriate. In addition, in this specification, when a plurality of configuration examples are shown in one embodiment mode, the configuration examples can be combined as appropriate.

[0283] (Embodiment 2) In this embodiment, a light-emitting device according to one embodiment of the present invention will be described with reference to FIGS.

[0284] [Configuration example 1 of light-emitting device] Fig. 2A shows a top view of the light emitting device, and Fig. 2B and Fig. 2C show cross-sectional views taken along dashed lines X1-Y1 and X2-Y2 in Fig. 2A. The light emitting device shown in Fig. 2A to Fig. 2C can be used, for example, in a lighting device. The light emitting device may be a bottom emission, top emission, or dual emission device.

[0285] 2B includes a substrate 490a, a substrate 490b, a conductive layer 406, a conductive layer 416, an insulating layer 405, an organic EL device 450 (a first electrode 401, an EL layer 402, and a second electrode 403), and an adhesive layer 407. The organic EL device 450 can also be referred to as a light-emitting element, an organic EL element, a light-emitting device, or the like. The light-emitting device of one embodiment of the present invention described in Embodiment 1 is preferably used for the organic EL device 450.

[0286] Organic EL device 450 has a first electrode 401 on a substrate 490a, an EL layer 402 on the first electrode 401, and a second electrode 403 on the EL layer 402. Organic EL device 450 is encapsulated by substrate 490a, adhesive layer 407, and substrate 490b.

[0287] Ends of the first electrode 401, the conductive layer 406, and the conductive layer 416 are covered with an insulating layer 405. The conductive layer 406 is electrically connected to the first electrode 401, and the conductive layer 416 is electrically connected to the second electrode 403. The conductive layer 406, covered with the insulating layer 405 via the first electrode 401, functions as an auxiliary wiring and is electrically connected to the first electrode 401. Having an auxiliary wiring electrically connected to the electrode of the organic EL device 450 is preferable because it can suppress voltage drops caused by electrode resistance. The conductive layer 406 may be provided on the first electrode 401. Furthermore, an auxiliary wiring electrically connected to the second electrode 403 may be provided on the insulating layer 405 or the like.

[0288] The substrate 490a and the substrate 490b can each be made of glass, quartz, ceramic, sapphire, organic resin, etc. Using a flexible material for the substrate 490a and the substrate 490b can increase the flexibility of the display device.

[0289] The light-emitting surface of the light-emitting device may be provided with one or more of the following: a light extraction structure to increase light extraction efficiency, an antistatic film to prevent dust from adhering, a water-repellent film to prevent dirt from adhering, a hard coat film to prevent scratches from occurring during use, and an impact absorbing layer.

[0290] Examples of insulating materials that can be used for the insulating layer 405 include resins such as acrylic resins and epoxy resins, and inorganic insulating materials such as silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, and aluminum oxide.

[0291] The adhesive layer 407 can be made of various curable adhesives, such as a photo-curable adhesive (e.g., an ultraviolet curable adhesive), a reactive curable adhesive, a thermosetting adhesive, or an anaerobic adhesive. Examples of such adhesives include epoxy resin, acrylic resin, silicone resin, phenolic resin, polyimide resin, imide resin, PVC (polyvinyl chloride) resin, PVB (polyvinyl butyral) resin, and EVA (ethylene vinyl acetate) resin. In particular, a material with low moisture permeability, such as epoxy resin, is preferable. Alternatively, a two-component resin may be used. Alternatively, an adhesive sheet or the like may be used.

[0292] The light-emitting device shown in FIG. 2C includes barrier layer 490c, conductive layer 406, conductive layer 416, insulating layer 405, organic EL device 450, adhesive layer 407, barrier layer 423, and substrate 490b.

[0293] Barrier layer 490c shown in FIG. 2C includes substrate 420, adhesive layer 422, and insulating layer 424 with high barrier properties.

[0294] 2C, organic EL device 450 is disposed between insulating layer 424 with high barrier properties and barrier layer 423. Therefore, even if a resin film with relatively low waterproof properties is used for substrate 420 and substrate 490b, it is possible to prevent impurities such as water from entering the organic EL device and shortening its lifespan.

[0295] Substrate 420 and substrate 490b may each be made of, for example, polyester resin such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), polyacrylonitrile resin, acrylic resin, polyimide resin, polymethyl methacrylate resin, polycarbonate (PC) resin, polyethersulfone (PES) resin, polyamide resin (nylon, aramid, etc.), polysiloxane resin, cycloolefin resin, polystyrene resin, polyamideimide resin, polyurethane resin, polyvinyl chloride resin, polyvinylidene chloride resin, polypropylene resin, polytetrafluoroethylene (PTFE) resin, ABS resin, cellulose nanofiber, etc. Substrate 420 and substrate 490b may also be made of glass having a thickness sufficient to provide flexibility.

[0296] An inorganic insulating film is preferably used as the insulating layer 424 having high barrier properties. Examples of the inorganic insulating film that can be used include a silicon nitride film, a silicon oxynitride film, a silicon oxide film, a silicon nitride oxide film, an aluminum oxide film, and an aluminum nitride film. Alternatively, a hafnium oxide film, an yttrium oxide film, a zirconium oxide film, a gallium oxide film, a tantalum oxide film, a magnesium oxide film, a lanthanum oxide film, a cerium oxide film, and a neodymium oxide film may also be used. Two or more of the above insulating films may be stacked.

[0297] The barrier layer 423 preferably has at least one inorganic film. For example, the barrier layer 423 can have a single-layer structure of an inorganic film or a laminated structure of an inorganic film and an organic film. The inorganic insulating film described above is suitable as the inorganic film. An example of the laminated structure is a structure in which a silicon oxynitride film, a silicon oxide film, an organic film, a silicon oxide film, and a silicon nitride film are formed in this order. By forming the barrier layer into a laminated structure of an inorganic film and an organic film, impurities (typically, hydrogen, water, etc.) that may enter the organic EL device 450 can be suitably suppressed.

[0298] The insulating layer 424 and the organic EL device 450, which have high barrier properties, can be formed directly on the flexible substrate 420. In this case, the adhesive layer 422 is not necessary. Alternatively, the insulating layer 424 and the organic EL device 450 can be formed on a rigid substrate via a release layer and then transferred to the substrate 420. For example, the release layer may be applied with heat, force, laser light, or the like to peel the insulating layer 424 and the organic EL device 450 from the rigid substrate, and then the substrate 420 may be attached using the adhesive layer 422 to transfer the insulating layer to the substrate 420. The release layer may be, for example, a laminated structure of inorganic films including a tungsten film and a silicon oxide film, or an organic resin film such as polyimide. When a rigid substrate is used, the insulating layer 424 can be formed at a higher temperature than when a resin substrate is used, resulting in a dense insulating film with extremely high barrier properties.

[0299] [Configuration example 2 of light-emitting device] A cross-sectional view of a light-emitting device is shown in Fig. 3A. The light-emitting device shown in Fig. 3A is an active matrix light-emitting device in which a transistor and a light-emitting device are electrically connected to each other.

[0300] The light emitting device shown in FIG. 3A includes a substrate 201, a transistor 210, a light emitting device 203R, a light emitting device 203G, a light emitting device 203B, a color filter 206R, a color filter 206G, a color filter 206B, a substrate 205, and the like.

[0301] In FIG. 3A, a transistor 210 is provided on a substrate 201, an insulating layer 202 is provided on the transistor 210, and light-emitting devices 203R, 203G, and 203B are provided on the insulating layer 202.

[0302] The transistor 210 and the light emitting devices 203R, 203G, and 203B are sealed in a space 207 surrounded by the substrate 201, the substrate 205, and the adhesive layer 208. The space 207 may be filled with, for example, a reduced pressure atmosphere, an inert atmosphere, or a resin.

[0303] The light emitting device shown in FIG. 3A has a configuration in which one pixel has a red sub-pixel (R), a green sub-pixel (G), and a blue sub-pixel (B).

[0304] A light-emitting device according to one embodiment of the present invention has a plurality of pixels arranged in a matrix. Each pixel has one or more sub-pixels. Each sub-pixel has one light-emitting device. For example, a pixel may have three sub-pixels (e.g., three colors of R, G, and B, or three colors of yellow (Y), cyan (C), and magenta (M)) or four sub-pixels (e.g., four colors of R, G, B, and white (W), or four colors of R, G, B, and Y).

[0305] FIG. 3B shows detailed structures of light-emitting device 203R, light-emitting device 203G, and light-emitting device 203B. Light-emitting devices 203R, 203G, and 203B share a common EL layer 213 and have a microcavity structure in which the optical distance between electrodes of each light-emitting device is adjusted according to the emission color of each light-emitting device. The light-emitting device of this embodiment preferably includes the light-emitting device of one embodiment of the present invention described in Embodiment 1. In particular, when a green phosphorescent light-emitting device is used as light-emitting device 203G, applying the structure of the light-emitting device of one embodiment of the present invention to light-emitting device 203G is preferable because high luminous efficiency and low driving voltage can be achieved. Note that the light-emitting device of one embodiment of the present invention is not limited to light-emitting device 203G and can also be used for light-emitting device 203R, light-emitting device 203B, and the like.

[0306] The first electrode 211 functions as a reflective electrode, and the second electrode 215 functions as a semi-transmissive and semi-reflective electrode.

[0307] Light emitting device 203R is adjusted so that the optical distance between first electrode 211 and second electrode 215 is 220R to enhance the intensity of red light. Similarly, light emitting device 203G is adjusted so that the optical distance between first electrode 211 and second electrode 215 is 220G to enhance the intensity of green light, and light emitting device 203B is adjusted so that the optical distance between first electrode 211 and second electrode 215 is 220B to enhance the intensity of blue light.

[0308] 3B, optical adjustment can be performed by forming conductive layer 212R on first electrode 211 in light-emitting device 203R, and by forming conductive layer 212G on first electrode 211 in light-emitting device 203G. Furthermore, in light-emitting device 203B, a conductive layer having a thickness different from that of conductive layer 212R and conductive layer 212G may be formed on first electrode 211 to adjust optical distance 220B. Note that, as shown in FIG. 3A, ends of first electrode 211, conductive layer 212R, and conductive layer 212G are covered with insulating layer 204.

[0309] 3A is a top-emission type light-emitting device in which light emitted from a light-emitting device is emitted through color filters of various colors formed on substrate 205. The color filters can pass specific wavelength ranges of visible light and block specific wavelength ranges.

[0310] In the red sub-pixel (R), light emitted from the light-emitting device 203R is output through a red color filter 206R. As shown in Fig. 3A, by providing a color filter 206R that transmits only light in the red wavelength range at a position overlapping the light-emitting device 203R, red light can be emitted from the light-emitting device 203R.

[0311] Similarly, in the green sub-pixel (G), light emitted from the light-emitting device 203G is emitted through the green color filter 206G, and in the blue sub-pixel (B), light emitted from the light-emitting device 203B is emitted through the blue color filter 206B.

[0312] A black matrix 209 (which can also be called a black layer) may be provided on the substrate 205. In this case, it is preferable that the ends of the color filters overlap with the black matrix 209. Furthermore, the color filters of each color and the black matrix 209 may be covered with an overcoat layer that transmits visible light.

[0313] 3C has a configuration in which one pixel has a red subpixel (R), a green subpixel (G), a blue subpixel (B), and a white subpixel (W). In Fig. 3C, light from the light-emitting device 203W of the white subpixel (W) is emitted to the outside of the light-emitting device without passing through a color filter.

[0314] The optical distance between first electrode 211 and second electrode 215 in light-emitting device 203W may be the same as or different from any of light-emitting devices 203R, 203G, and 203B.

[0315] For example, when the light emitted from light-emitting device 203W is white light with a low color temperature, and the intensity of blue light is to be increased, it is preferable to set the optical distance in light-emitting device 203W equal to optical distance 220B in light-emitting device 203B, as shown in Fig. 3C. This allows the light obtained from light-emitting device 203W to approach white light with a desired color temperature.

[0316] While Fig. 3A shows an example in which a common EL layer 213 is used for the light-emitting devices of the subpixels of each color, as shown in Fig. 4A, different EL layers may be used for the light-emitting devices of the subpixels of each color. The above-described microcavity structure can also be applied to Fig. 4A.

[0317] 4A shows an example in which light-emitting device 203R has EL layer 213R, light-emitting device 203G has EL layer 213G, and light-emitting device 203B has EL layer 213B. EL layers 213R, 213G, and 213B may have common layers. For example, EL layers 213R, 213G, and 213B may have different light-emitting layer configurations and other layers may be common layers. In FIG. 4A, light emitted by light-emitting devices 203R, 203G, and 203B may be extracted through a color filter or without a color filter.

[0318] Although a top-emission light-emitting device is shown in FIG. 3A, a light-emitting device having a structure in which light is extracted from the substrate 201 side on which the transistor 210 is formed (bottom-emission light-emitting device) as shown in FIG. 4B is also one embodiment of the present invention.

[0319] In a bottom-emission light-emitting device, it is preferable to provide color filters of each color between the substrate 201 and the light-emitting devices. 4B shows an example in which a transistor 210 is formed on the substrate 201, an insulating layer 202a is formed on the transistor 210, color filters 206R, 206G, and 206B are formed on the insulating layer 202a, an insulating layer 202b is formed on the color filters 206R, 206G, and 206B, and light-emitting devices 203R, 203G, and 203B are formed on the insulating layer 202b.

[0320] In the case of a top-emission light-emitting device, a light-shielding substrate and a light-transmitting substrate can be used as the substrate 201, and a light-transmitting substrate can be used as the substrate 205.

[0321] In the case of a bottom-emission light-emitting device, the substrate 205 can be a light-shielding substrate or a light-transmitting substrate, and the substrate 201 can be a light-transmitting substrate.

[0322] [Configuration example 3 of light-emitting device] The light-emitting device of one embodiment of the present invention can be a passive matrix type or an active matrix type. An active matrix type light-emitting device will be described with reference to FIG.

[0323] Fig. 5A shows a top view of the light emitting device, and Fig. 5B shows a cross-sectional view taken along the dashed dotted line AA' shown in Fig. 5A.

[0324] The active matrix light-emitting device shown in FIGS. 5A and 5B includes a pixel portion 302, a circuit portion 303, a circuit portion 304a, and a circuit portion 304b.

[0325] The circuit portion 303, the circuit portion 304a, and the circuit portion 304b can function as a scan line driver circuit (gate driver) or a signal line driver circuit (source driver), or may be a circuit that electrically connects an external gate driver or source driver to the pixel portion 302.

[0326] A lead wiring 307 is provided on the first substrate 301. The lead wiring 307 is electrically connected to an FPC 308, which is an external input terminal. The FPC 308 transmits external signals (e.g., video signals, clock signals, start signals, reset signals, etc.) and potentials to the circuit portion 303, the circuit portion 304a, and the circuit portion 304b. A printed wiring board (PWB) may be attached to the FPC 308. The configuration shown in FIGS. 5A and 5B can also be referred to as a light-emitting module having a light-emitting device (or light-emitting apparatus) and an FPC.

[0327] The pixel portion 302 has a plurality of pixels each having an organic EL device 317, a transistor 311, and a transistor 312. The transistor 312 is electrically connected to a first electrode 313 of the organic EL device 317. The transistor 311 functions as a switching transistor. The transistor 312 functions as a current control transistor. Note that the number of transistors included in each pixel is not particularly limited and can be appropriately provided as needed.

[0328] The circuit portion 303 has a plurality of transistors including a transistor 309 and a transistor 310. The circuit portion 303 may be formed of a circuit including transistors of the same conductivity type (either N-type or P-type), or may be formed of a CMOS circuit including N-type transistors and P-type transistors. The circuit portion 303 may also have a configuration including an external driver circuit.

[0329] The structure of the transistor included in the light-emitting device of this embodiment is not particularly limited. For example, a planar transistor, a staggered transistor, an inverted staggered transistor, or the like can be used. Furthermore, either a top-gate or bottom-gate transistor structure may be used. Alternatively, gates may be provided above and below a semiconductor layer in which a channel is formed.

[0330] 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.

[0331] The semiconductor layer of the transistor preferably contains a metal oxide (also referred to as an oxide semiconductor). Alternatively, the semiconductor layer of the transistor may contain silicon. Examples of silicon include amorphous silicon and crystalline silicon (such as low-temperature polysilicon and single-crystal silicon).

[0332] The semiconductor layer preferably contains, for example, indium, M (wherein M is one or more elements selected from gallium, aluminum, silicon, boron, yttrium, tin, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium), and zinc. In particular, M is preferably one or more elements selected from aluminum, gallium, yttrium, and tin.

[0333] In particular, it is preferable to use an oxide containing indium (In), gallium (Ga), and zinc (Zn) (also referred to as IGZO) as the semiconductor layer.

[0334] When the semiconductor layer is an In-M-Zn oxide, the sputtering target used to deposit the In-M-Zn oxide preferably has an atomic ratio of In equal to or greater than the atomic ratio of M. Examples of atomic ratios of metal elements in such sputtering targets include In:M:Zn=1:1:1, In:M:Zn=1:1:1.2, In:M:Zn=2:1:3, In:M:Zn=3:1:2, In:M:Zn=4:2:3, In:M:Zn=4:2:4.1, In:M:Zn=5:1:6, In:M:Zn=5:1:7, In:M:Zn=5:1:8, In:M:Zn=6:1:6, and In:M:Zn=5:2:5.

[0335] The transistors included in the circuit portion 303, the circuit portion 304a, and the circuit portion 304b may have the same structure or different structures from the transistors included in the pixel portion 302. The transistors included in the circuit portion 303, the circuit portion 304a, and the circuit portion 304b may all have the same structure or may have two or more types. Similarly, the transistors included in the pixel portion 302 may all have the same structure or may have two or more types.

[0336] The end of the first electrode 313 is covered with an insulating layer 314. The insulating layer 314 can be made of one or both of an organic compound such as a negative photosensitive resin or a positive photosensitive resin (acrylic resin), and an inorganic compound such as silicon oxide, silicon oxynitride, or silicon nitride. The upper or lower end of the insulating layer 314 preferably has a curved surface. This can improve the coverage of a film formed on the insulating layer 314.

[0337] An EL layer 315 is provided over the first electrode 313, and a second electrode 316 is provided over the EL layer 315. The EL layer 315 includes at least one layer selected from the group consisting of a light-emitting layer, a hole-injection layer, a hole-transport layer, an electron-transport layer, an electron-injection layer, and a charge-generation layer. The light-emitting device according to one embodiment of the present invention described in Embodiment 1 is preferably used as the organic EL device 317. This can increase the luminous efficiency of the organic EL device 317 and reduce its driving voltage.

[0338] The plurality of transistors and the plurality of organic EL devices 317 are sealed by the first substrate 301, the second substrate 306, and the sealant 305. A space 318 surrounded by the first substrate 301, the second substrate 306, and the sealant 305 may be filled with an inert gas (nitrogen, argon, etc.) or an organic substance (including the sealant 305).

[0339] The sealing material 305 can be made of epoxy resin, glass frit, or the like. Note that it is preferable to use a material that is as impermeable to moisture and oxygen as possible for the sealing material 305. When glass frit is used as the sealing material, it is preferable that the first substrate 301 and the second substrate 306 are glass substrates in terms of adhesiveness.

[0340] 5C and 5D show examples of transistors that can be used in the light-emitting device.

[0341] The transistor 320 shown in FIG. 5C includes a conductive layer 321 functioning as a gate, an insulating layer 328 functioning as a gate insulating layer, a semiconductor layer 327 having a channel formation region 327i and a pair of low-resistance regions 327n, a conductive layer 322a connected to one of the pair of low-resistance regions 327n, a conductive layer 322b connected to the other of the pair of low-resistance regions 327n, an insulating layer 325 functioning as a gate insulating layer, a conductive layer 323 functioning as a gate, and an insulating layer 324 covering the conductive layer 323. The insulating layer 328 is located between the conductive layer 321 and the channel formation region 327i. The insulating layer 325 is located between the conductive layer 323 and the channel formation region 327i. The transistor 320 is preferably covered with an insulating layer 326. The insulating layer 326 may be included as a component of the transistor 320.

[0342] The conductive layer 322a and the conductive layer 322b are each connected to the low-resistance region 327n through an opening provided in the insulating layer 324. One of the conductive layer 322a and the conductive layer 322b functions as a source, and the other functions as a drain.

[0343] The insulating layer 325 is provided to overlap at least the channel formation region 327i of the semiconductor layer 327. The insulating layer 325 may cover the top surface and side surfaces of the pair of low-resistance regions 327n.

[0344] 5D includes a conductive layer 331 functioning as a gate, an insulating layer 338 functioning as a gate insulating layer, conductive layers 332a and 332b functioning as a source and a drain, a semiconductor layer 337, an insulating layer 335 functioning as a gate insulating layer, and a conductive layer 333 functioning as a gate. The insulating layer 338 is located between the conductive layer 331 and the semiconductor layer 337. The insulating layer 335 is located between the conductive layer 333 and the semiconductor layer 337. The transistor 330 is preferably covered with an insulating layer 334. The insulating layer 334 may be included as a component of the transistor 330.

[0345] The transistor 320 and the transistor 330 have a structure in which a semiconductor layer in which a channel is formed is sandwiched between two gates. The two gates may be connected and the same signal may be supplied to drive the transistor. Alternatively, the threshold voltage of the transistor may be controlled by applying a potential for controlling the threshold voltage to one of the two gates and a potential for driving to the other.

[0346] At least one insulating layer covering the transistor is preferably made of a material that is resistant to the diffusion of impurities such as water and hydrogen. This allows the insulating layer to function as a barrier layer. This structure effectively prevents impurities from diffusing into the transistor from the outside, thereby improving the reliability of the light-emitting device.

[0347] An inorganic insulating film is preferably used for each of the insulating layer 325, the insulating layer 326, the insulating layer 328, the insulating layer 334, the insulating layer 335, and the insulating layer 338. Examples of the inorganic insulating film that can be used include a silicon nitride film, a silicon oxynitride film, a silicon oxide film, a silicon nitride oxide film, an aluminum oxide film, and an aluminum nitride film. Alternatively, a hafnium oxide film, an yttrium oxide film, a zirconium oxide film, a gallium oxide film, a tantalum oxide film, a magnesium oxide film, a lanthanum oxide film, a cerium oxide film, a neodymium oxide film, and the like may also be used. Two or more of the above insulating films may be stacked.

[0348] Materials that can be used for various conductive layers constituting a light-emitting device include metals such as aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum, silver, tantalum, and tungsten, or alloys containing these metals as the main component. Films containing these materials can be used as single layers or multilayer structures. Examples include a single-layer structure of an aluminum film containing silicon, a two-layer structure in which an aluminum film is stacked on a titanium film, a two-layer structure in which an aluminum film is stacked on a tungsten film, a two-layer structure in which a copper film is stacked on a copper-magnesium-aluminum alloy film, a two-layer structure in which a copper film is stacked on a titanium film, a two-layer structure in which a copper film is stacked on a tungsten film, a three-layer structure in which a titanium film or titanium nitride film is stacked on an aluminum film or copper film, and a three-layer structure in which a titanium film or titanium nitride film is further stacked on top of that, and a three-layer structure in which a molybdenum film or molybdenum nitride film is stacked on an aluminum film or copper film, and a molybdenum film or molybdenum nitride film is further stacked on top of that. Alternatively, oxides such as indium oxide, tin oxide, or zinc oxide may be used. Furthermore, copper containing manganese is preferably used because it improves the controllability of the shape by etching.

[0349] This embodiment mode can be combined with other embodiment modes as appropriate.

[0350] (Embodiment 3) In this embodiment, a light-receiving device, a light-emitting and receiving device, and a light-emitting and receiving apparatus according to one embodiment of the present invention will be described with reference to drawings.

[0351] [Configuration example of a light receiving device] In this embodiment, a light-receiving device having a function of detecting visible light or near-infrared light will be described. Figures 6A and 6B show an example of a light-receiving device having a layer containing an organic compound between a pair of electrodes.

[0352] 6A has a structure in which a layer 105 containing an organic compound is sandwiched between a first electrode 101 and a second electrode 102. The layer 105 containing an organic compound has at least an active layer.

[0353] FIG. 6B shows an example of a layer structure of the organic compound-containing layer 105. In this embodiment, a case where the first electrode 101 functions as an anode and the second electrode 102 functions as a cathode will be described as an example. The light-receiving device detects light incident on the light-receiving device, generates charges, and extracts them as a current by applying a reverse bias between the first electrode 101 and the second electrode 102. The organic compound-containing layer 105 has a structure in which a hole transport layer 116, an active layer 117, and an electron transport layer 118 are sequentially stacked on the first electrode 101. The hole transport layer 116, the active layer 117, and the electron transport layer 118 may each have a single-layer structure or a stacked structure. When the first electrode 101 is a cathode and the second electrode 102 is an anode, the stacking order is reversed.

[0354] The active layer 117 includes a semiconductor. Examples of the semiconductor include an inorganic semiconductor such as silicon and an organic semiconductor including an organic compound. In this embodiment, an example in which an organic semiconductor is used as the semiconductor included in the active layer is shown. By using an organic semiconductor, the light-emitting layer of the light-emitting device and the active layer 117 can be formed by the same method (for example, vacuum deposition), which is preferable because a common manufacturing apparatus can be used.

[0355] The active layer 117 has an n-type semiconductor material, such as fullerene (e.g., C 60 , C 70 ), and fullerene derivatives and other electron-accepting organic semiconductor materials.

[0356] Examples of n-type semiconductor materials include metal complexes having a quinoline skeleton, metal complexes having a benzoquinoline skeleton, metal complexes having an oxazole skeleton, metal complexes having a thiazole skeleton, oxadiazole derivatives, triazole derivatives, imidazole derivatives, oxazole derivatives, thiazole derivatives, phenanthroline derivatives, quinoline derivatives, benzoquinoline derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, naphthalene derivatives, anthracene derivatives, coumarin derivatives, rhodamine derivatives, triazine derivatives, and quinone derivatives.

[0357] Examples of p-type semiconductor materials that the active layer 117 has include electron-donating organic semiconductor materials such as copper(II) phthalocyanine (CuPc), tetraphenyldibenzoperiflanthene (DBP), zinc phthalocyanine (ZnPc), tin phthalocyanine (SnPc), and quinacridone.

[0358] Examples of p-type semiconductor materials include carbazole derivatives, thiophene derivatives, furan derivatives, and compounds having an aromatic amine skeleton. Examples of p-type semiconductor materials include naphthalene derivatives, anthracene derivatives, pyrene derivatives, triphenylene derivatives, fluorene derivatives, pyrrole derivatives, benzofuran derivatives, benzothiophene derivatives, indole derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, indolocarbazole derivatives, porphyrin derivatives, phthalocyanine derivatives, naphthalocyanine derivatives, quinacridone derivatives, polyphenylenevinylene derivatives, polyparaphenylene derivatives, polyfluorene derivatives, polyvinylcarbazole derivatives, and polythiophene derivatives.

[0359] The HOMO level of the electron-donating organic semiconductor material is preferably higher than the HOMO level of the electron-accepting organic semiconductor material, and the LUMO level of the electron-donating organic semiconductor material is preferably higher than the LUMO level of the electron-accepting organic semiconductor material.

[0360] It is preferable to use a spherical fullerene as the electron-accepting organic semiconductor material and a planar organic semiconductor material as the electron-donating organic semiconductor material. Molecules with similar shapes tend to aggregate together, and when molecules of the same type aggregate, the energy levels of their molecular orbitals become close, which can improve carrier transport properties.

[0361] For example, the active layer 117 is preferably formed by co-evaporation of an n-type semiconductor and a p-type semiconductor, or may have a stacked structure of a layer having an n-type semiconductor and a layer having a p-type semiconductor.

[0362] For the first electrode 101 and the second electrode 102, the same materials as those of the electrodes of the light-emitting device described in Embodiment 1 can be used.

[0363] The hole-transport layer 116 preferably has a stacked structure of the first hole-transport layer 112a, the buffer layer 119, and the second hole-transport layer 112b described in Embodiment 1. Alternatively, the hole-transport layer 116 may include one or more of the materials that can be used for the hole-injection layer 111, the first hole-transport layer 112a, the buffer layer 119, and the second hole-transport layer 112b of the light-emitting device described in Embodiment 1. The hole-transport layer 116 may have a single-layer structure or a stacked structure. That is, the hole-transport layer 116 may have a structure similar to one or more of the hole-injection layer 111, the first hole-transport layer 112a, the buffer layer 119, and the second hole-transport layer 112b of the light-emitting device described in Embodiment 1.

[0364] The electron transport layer 118 can be made of one or more of the materials that can be used for the electron transport layer 114 and the electron injection layer 115 of the light-emitting device described in Embodiment 1. That is, the electron transport layer 118 can have the same structure as one or both of the electron transport layer 114 and the electron injection layer 115 of the light-emitting device described in Embodiment 1.

[0365] [Configuration example of a light-emitting / receiving device] In the layered structure shown in Figures 6A and 6B, by providing a light-emitting layer 113 as the layer 105 containing an organic compound in addition to a hole transport layer 116, an active layer 117, and an electron transport layer 118, the layer can function as a light-receiving and light-emitting device.

[0366] The light-emitting layer 113 is preferably provided between the hole-transporting layer 116 and the active layer 117, or between the active layer 117 and the electron-transporting layer 118. Furthermore, it is preferable to provide a buffer layer between the light-emitting layer 113 and the active layer 117.

[0367] Since the light-receiving and light-emitting device can function as both a light-emitting device and a light-receiving device, the number of devices arranged in one pixel can be reduced, which makes it easier to achieve higher definition, a higher aperture ratio, and higher resolution in display devices.

[0368] [Configuration example of light-emitting / receiving device] The light receiving and emitting device has a light receiving function and a light emitting function. In the following, a display device having a light receiving function will be described as an example of the light receiving and emitting device.

[0369] The display device of this embodiment has a light-receiving device or a light-emitting and receiving device in addition to a light-emitting device.

[0370] The display device of this embodiment has a function of displaying an image using a light-emitting device (and a light-emitting and receiving device). That is, the light-emitting device (and a light-emitting and receiving device) functions as a display device.

[0371] The light-emitting device functions as a display device (also referred to as a display element). As the light-emitting device, an EL device such as an organic light-emitting diode (OLED) or a quantum-dot light-emitting diode (QLED) is preferably used. Alternatively, an LED such as a micro light-emitting diode (LED) can also be used as the light-emitting device. The light-emitting device of one embodiment of the present invention described in Embodiment 1 has high light extraction efficiency and a low driving voltage, and therefore can be suitably used for the display device of one embodiment of the present invention.

[0372] The display device of this embodiment mode has a function of detecting light using a light receiving device or a light emitting and receiving device.

[0373] When the light receiving device or the light emitting and receiving device is used as an image sensor, the display device of the present embodiment can capture an image. For example, the display device of the present embodiment can be used as a scanner.

[0374] For example, an image sensor can be used to acquire data related to biometric information such as fingerprints and palm prints. That is, a biometric authentication sensor can be built into the display device. By building a biometric authentication sensor into the display device, the number of components in the electronic device can be reduced compared to when a biometric authentication sensor is provided separately from the display device, and the electronic device can be made smaller and lighter.

[0375] Furthermore, when the light receiving device or the light emitting and receiving device is used as a touch sensor, the display device of the present embodiment can detect the proximity or contact of an object.

[0376] As the light-receiving device, for example, a pn-type or pin-type photodiode can be used. In particular, it is preferable to use an organic photodiode having a layer containing an organic compound as the light-receiving device. Organic photodiodes can be easily made thin, lightweight, and large-area, and have a high degree of freedom in shape and design, and therefore can be applied to various display devices. The light-receiving device of one embodiment of the present invention described in this embodiment can be suitably used in the display device of one embodiment of the present invention.

[0377] A display device according to one embodiment of the present invention includes an organic EL device as a light-emitting device and an organic photodiode as a light-receiving device. The organic EL device and the organic photodiode can be formed on the same substrate. Therefore, the organic photodiode can be built into a display device using the organic EL device.

[0378] The light-emitting and receiving device can be manufactured by adding an active layer of a light-receiving device to the above-described light-emitting device. For example, the active layer of a pn-type or pin-type photodiode can be used for the light-emitting and receiving device. In particular, the active layer of an organic photodiode having a layer containing an organic compound is preferably used for the light-emitting and receiving device. The light-emitting and receiving device of one embodiment of the present invention described in this embodiment can be suitably used for the display device of one embodiment of the present invention.

[0379] Specifically, a light-emitting and receiving device can be fabricated by combining an organic EL device and an organic photodiode. For example, a light-emitting and receiving device can be fabricated by adding an active layer of an organic photodiode to the layered structure of an organic EL device. Furthermore, a light-emitting and receiving device fabricated by combining an organic EL device and an organic photodiode can suppress an increase in the number of film formation processes by simultaneously depositing layers that can be configured in common with the organic EL device.

[0380] In a display device according to one embodiment of the present invention, a light-emitting device can be used as a light source for a sensor. Therefore, a light-receiving portion and a light source do not need to be provided separately from the display device, and the number of components in an electronic device can be reduced.

[0381] Next, the detailed configuration of the display device will be described. The specific structure of the display device will be mainly described using Figures 6C and 6D, and the specific functions of the display device will be mainly described using Figures 7A to 7C.

[0382] [Display device 500A] FIG. 6C shows a cross-sectional view of display device 500A.

[0383] The display device 500A includes a light receiving device 510, a light emitting device 590, a transistor 531, a transistor 532, and the like between a pair of substrates (substrate 551 and substrate 552).

[0384] The light-emitting device 590 has a pixel electrode 591, a buffer layer 512, a light-emitting layer 593, a buffer layer 514, and a common electrode 515 stacked in this order. The buffer layer 512 can have one or both of a hole injection layer and a hole transport layer. The light-emitting layer 593 contains an organic compound. The buffer layer 514 can have one or both of an electron injection layer and an electron transport layer. The light-emitting device 590 has a function of emitting visible light. Note that the display device 500A may further have a light-emitting device 590 that has a function of emitting infrared light.

[0385] The light-receiving device 510 has a pixel electrode 511, a buffer layer 512, an active layer 513, a buffer layer 514, and a common electrode 515 stacked in this order. In the light-receiving device 510, the buffer layer 512 functions as a hole transport layer. The active layer 513 contains an organic compound. The light-receiving device 510 has a function of detecting visible light. In the light-receiving device 510, the buffer layer 514 functions as an electron transport layer. The light-receiving device 510 may further have a function of detecting infrared light.

[0386] The buffer layer 512, the buffer layer 514, and the common electrode 515 are layers common to the light-emitting device 590 and the light-receiving device 510 and are provided across them.

[0387] In the present embodiment, it is assumed that the pixel electrode 511 functions as an anode and the common electrode 515 functions as a cathode in both the light-emitting device 590 and the light-receiving device 510. In other words, by driving the light-receiving device 510 by applying a reverse bias between the pixel electrode 511 and the common electrode 515, the display device 500A can detect light incident on the light-receiving device 510, generate charges, and extract them as a current.

[0388] The pixel electrode 511, the buffer layer 512, the active layer 513, the light-emitting layer 593, the buffer layer 514, and the common electrode 515 may each have a single-layer structure or a multilayer structure.

[0389] The pixel electrode 511 and the pixel electrode 591 are located on an insulating layer 533. The ends of the pixel electrode 511 and the pixel electrode 591 are each covered with an insulating layer 534. The adjacent pixel electrodes 511 and 591 are electrically insulated (or electrically separated) from each other by the insulating layer 534.

[0390] An organic insulating film is suitable for the insulating layer 534. Materials that can be used for the organic insulating film include acrylic resin, polyimide resin, epoxy resin, polyamide resin, polyimideamide resin, siloxane resin, benzocyclobutene resin, phenol resin, and precursors of these resins. The insulating layer 534 may have a function of transmitting visible light or a function of blocking visible light.

[0391] The materials and thicknesses of the pair of electrodes of the light-receiving device 510 and the light-emitting device 590 can be made the same, which leads to a reduction in manufacturing cost of the display device and a simplification of the manufacturing process.

[0392] In the light-receiving device 510, the buffer layer 512, the active layer 513, and the buffer layer 514, which are respectively located between the pixel electrode 511 and the common electrode 515, can also be referred to as organic layers (layers containing an organic compound). The pixel electrode 511 preferably has a function of reflecting visible light. The common electrode 515 has a function of transmitting visible light. Note that, when the light-receiving device 510 is configured to detect infrared light, the common electrode 515 has a function of transmitting infrared light. Furthermore, the pixel electrode 511 preferably has a function of reflecting infrared light.

[0393] The light receiving device 510 has a function of detecting light. Specifically, the light receiving device 510 is a photoelectric conversion device (also referred to as a photoelectric conversion element) that receives light 522 incident from outside the display device 500A and converts the light 522 into an electrical signal. The light 522 can also be said to be light emitted by the light emitting device 590 and reflected by an object. The light 522 may also be incident on the light receiving device 510 via a lens or the like provided in the display device 500A.

[0394] In the light-emitting device 590, the buffer layer 512, the light-emitting layer 593, and the buffer layer 514, which are respectively located between the pixel electrode 591 and the common electrode 515, can be collectively referred to as an EL layer. The EL layer has at least the light-emitting layer 593. The pixel electrode 591 preferably has a function of reflecting visible light. The common electrode 515 has a function of transmitting visible light. When the display device 500A has a configuration including a light-emitting device that emits infrared light, the common electrode 515 has a function of transmitting infrared light. Furthermore, the pixel electrode 591 preferably has a function of reflecting infrared light.

[0395] The light-emitting device 590 has a function of emitting visible light. Specifically, the light-emitting device 590 is an electroluminescent device that emits light toward the substrate 552 by applying a voltage between a pixel electrode 591 and a common electrode 515 (see light 521).

[0396] A pixel electrode 511 of the light-receiving device 510 is electrically connected to the source or drain of the transistor 531 through an opening provided in the insulating layer 533 .

[0397] A pixel electrode 591 of the light-emitting device 590 is electrically connected to the source or drain of the transistor 532 through an opening provided in the insulating layer 533 .

[0398] The transistor 531 and the transistor 532 are adjacent to each other on the same layer (substrate 551 in FIG. 6C).

[0399] At least a part of the circuit electrically connected to the light-receiving device 510 is preferably formed using the same material and in the same process as the circuit electrically connected to the light-emitting device 590. This allows the display device to be thinner and the manufacturing process to be simplified compared to when the two circuits are formed separately.

[0400] Preferably, the light-receiving device 510 and the light-emitting device 590 are each covered with a protective layer 595. In FIG. 6C , the protective layer 595 is provided on and in contact with the common electrode 515. Providing the protective layer 595 can prevent impurities such as water from entering the light-receiving device 510 and the light-emitting device 590, thereby improving the reliability of the light-receiving device 510 and the light-emitting device 590. In addition, the protective layer 595 and the substrate 552 are bonded together by an adhesive layer 553.

[0401] A light-shielding layer 554 is provided on the surface of the substrate 552 facing the substrate 551. The light-shielding layer 554 has openings at positions overlapping the light-emitting device 590 and the light-receiving device 510.

[0402] Here, the light receiving device 510 detects light emitted by the light emitting device 590 and reflected by the object. However, there are cases where the light emitted by the light emitting device 590 is reflected within the display device 500A and enters the light receiving device 510 without passing through the object. The light blocking layer 554 can suppress the influence of such stray light. This reduces noise and increases the sensitivity of the sensor using the light receiving device 510.

[0403] The light-shielding layer 554 may be made of a material that blocks light emitted from the light-emitting device. The light-shielding layer 554 preferably absorbs visible light. For example, the light-shielding layer 554 may be made of a black matrix using a metal material or a resin material containing a pigment (such as carbon black) or a dye. The light-shielding layer 554 may have a laminated structure of at least two layers of a red color filter, a green color filter, and a blue color filter.

[0404] [Display device 500B] 6D shows a cross-sectional view of display device 500 B. In the description of display device 500 B, the description of the same configuration as that of display device 500 A described above may be omitted.

[0405] The display device 500B includes a light-emitting device 590B, a light-emitting device 590G, and a light-receiving and light-emitting device 580SR.

[0406] The light-emitting device 590B has a pixel electrode 591B, a buffer layer 512, a light-emitting layer 593B, a buffer layer 514, and a common electrode 515 stacked in this order. The light-emitting device 590B has a function of emitting blue light 521B. The light-emitting device 590B is electrically connected to a transistor 532B.

[0407] The light-emitting device 590G includes a pixel electrode 591G, a buffer layer 512, a light-emitting layer 593G, a buffer layer 514, and a common electrode 515, which are stacked in this order. The light-emitting device 590G has a function of emitting green light 521G. The light-emitting device 590G is electrically connected to a transistor 532G.

[0408] The light emitting and receiving device 580SR has a pixel electrode 511, a buffer layer 512, an active layer 513, a light emitting layer 593R, a buffer layer 514, and a common electrode 515 stacked in this order. The light emitting and receiving device 580SR has a function of emitting red light 521R and a function of detecting light 522. The light emitting and receiving device 580SR is electrically connected to the transistor 531.

[0409] [Display device 500C] A display device 500C shown in FIG. 7A includes a substrate 551, a substrate 552, a light receiving device 510, a light emitting device 590R, a light emitting device 590G, a light emitting device 590B, a functional layer 555, and the like.

[0410] The light-emitting device 590R, the light-emitting device 590G, the light-emitting device 590B, and the light-receiving device 510 are provided between a substrate 551 and a substrate 552. The light-emitting device 590R, the light-emitting device 590G, and the light-emitting device 590B emit red (R), green (G), or blue (B) light, respectively.

[0411] The display device 500C has a plurality of pixels arranged in a matrix. Each pixel has one or more sub-pixels. Each sub-pixel has one light-emitting device. For example, the pixel may have three sub-pixels (e.g., three colors of R, G, and B, or three colors of yellow (Y), cyan (C), and magenta (M)), or four sub-pixels (e.g., four colors of R, G, B, and white (W), or four colors of R, G, B, and Y). The pixel further has a light-receiving device 510. The light-receiving device 510 may be provided in all pixels or in some pixels. Alternatively, one pixel may have multiple light-receiving devices 510.

[0412] 7A shows a state in which a finger 520 is approaching the surface of the substrate 552. A portion of the light emitted by the light-emitting device 590G is reflected by the finger 520. Then, a portion of the reflected light is incident on the light-receiving device 510, thereby making it possible to detect that the finger 520 is near the substrate 552. In other words, the display device 500C can function as a non-contact touch panel. Note that, since it can detect even when the finger 520 comes into contact with the substrate 552, the display device 500C can also function as a contact-type touch panel (also simply referred to as a touch panel).

[0413] The functional layer 555 has a circuit for driving the light-emitting device 590R, the light-emitting device 590G, and the light-emitting device 590B, and a circuit for driving the light-receiving device 510. The functional layer 555 is provided with a switch, a transistor, a capacitor, wiring, and the like. Note that when the light-emitting device 590R, the light-emitting device 590G, the light-emitting device 590B, and the light-receiving device 510 are driven by a passive matrix method, a configuration without providing a switch and a transistor is also possible.

[0414] [Display device 500D] The display device 500D shown in FIG. 7B includes a light-emitting device 590IR in addition to the configuration illustrated in FIG. 7A. The light-emitting device 590IR is a light-emitting device that emits infrared light IR. In other words, the display device 500D is configured to include a light-emitting device that emits visible light, a light-emitting device that emits infrared light, and a light-receiving device. In this case, it is preferable that the light-receiving device 510 be able to receive at least the infrared light IR emitted by the light-emitting device 590IR. It is more preferable that the light-receiving device 510 be able to receive both visible light and infrared light.

[0415] As shown in FIG. 7B, when a finger 520 touches the substrate 552, the infrared light IR emitted from the light-emitting device 590IR is reflected by the finger 520, and a portion of the reflected light is incident on the light-receiving device 510, thereby obtaining position information of the finger 520.

[0416] [Display device 500E] The display device 500E shown in FIG. 7C includes a light-emitting device 590B, a light-emitting device 590G, and a light-receiving and light-emitting device 580SR. The light-receiving and light-emitting device 580SR functions as a light-emitting device that emits red (R) light and as a photoelectric conversion device that receives visible light. That is, the display device 500E includes a light-emitting device that emits visible light and a light-receiving and light-emitting device that emits and receives visible light. FIG. 7C shows an example in which the light-receiving and light-emitting device 580SR receives green (G) light emitted by the light-emitting device 590G. The light-receiving and light-emitting device 580SR may also receive blue (B) light emitted by the light-emitting device 590B. The light-receiving and light-emitting device 580SR may also receive both green and blue light.

[0417] For example, the light receiving and emitting device 580SR preferably receives light with a shorter wavelength than the light it emits. The light receiving and emitting device 580SR may also be configured to receive light with a longer wavelength than the light it emits (e.g., infrared light). The light receiving and emitting device 580SR may also be configured to receive light with a wavelength similar to the light it emits, but in that case, the light it emits may also be received, which may result in a decrease in light emission efficiency. Therefore, the light receiving and emitting device 580SR is preferably configured so that the peaks of its emission spectrum and its absorption spectrum do not overlap as much as possible.

[0418] Furthermore, the light emitted by the light receiving and emitting device is not limited to red light. Furthermore, the light emitted by the light emitting device is not limited to a combination of green light and blue light. For example, the light receiving and emitting device may emit green or blue light and receive light of a different wavelength from the light it emits.

[0419] In this way, the light receiving and emitting device 580SR functions as both a light emitting device and a light receiving device, thereby reducing the number of devices arranged in one pixel, and thus facilitating the realization of higher definition, a higher aperture ratio, and higher resolution in the display device.

[0420] This embodiment mode can be combined with other embodiment modes as appropriate.

[0421] (Fourth embodiment) In this embodiment, electronic devices of one embodiment of the present invention will be described with reference to drawings.

[0422] Examples of electronic devices include television sets, computer monitors, digital cameras, digital video cameras, digital photo frames, mobile phones (also called mobile phones or mobile phone devices), portable game consoles, personal digital assistants, audio playback devices, large game machines such as pachinko machines, biometric authentication devices, and testing equipment.

[0423] The electronic devices of this embodiment have high emission efficiency and low driving voltage because they include the light-emitting device of one embodiment of the present invention in their display portions. Note that the electronic devices of one embodiment of the present invention are not limited to those including the light-emitting device of one embodiment of the present invention, and may include the light-receiving device of one embodiment of the present invention or the light-receiving and light-emitting device of one embodiment of the present invention.

[0424] The display unit of the electronic device of this embodiment can display images with resolutions of, for example, full high definition, 4K2K, 8K4K, 16K8K, or higher. The screen size of the display unit can be 20 inches or more diagonally, 30 inches or more diagonally, 50 inches or more diagonally, 60 inches or more diagonally, or 70 inches or more diagonally.

[0425] Since the electronic device according to one embodiment of the present invention is flexible, it can be incorporated along the curved surface of the inner or outer wall of a house or building, or the interior or exterior of an automobile.

[0426] Furthermore, the electronic device of one embodiment of the present invention may include a secondary battery, and it is preferable that the secondary battery can be charged using contactless power transmission.

[0427] Examples of secondary batteries include lithium ion secondary batteries such as lithium polymer batteries (lithium ion polymer batteries) that use a gel electrolyte, nickel-metal hydride batteries, nickel-cadmium batteries, organic radical batteries, lead-acid batteries, air secondary batteries, nickel-zinc batteries, and silver-zinc batteries.

[0428] The electronic device of one embodiment of the present invention may include an antenna. By receiving a signal through the antenna, images, information, or the like can be displayed on a display portion. When the electronic device includes an antenna and a secondary battery, the antenna may be used for contactless power transmission.

[0429] The electronic device of this embodiment may have a sensor (including a function to measure 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 rays).

[0430] The electronic device of the present embodiment can have various functions, such as a function to display various information (still images, videos, text images, etc.) on a display unit, a touch panel function, a function to display a calendar, date, time, etc., a function to execute various software (programs), a wireless communication function, a function to read out programs or data recorded on a recording medium, etc.

[0431] 8A shows an example of a television device. A television device 7100 has a display unit 7000 built into a housing 7101. Here, the housing 7101 is supported by a stand 7103.

[0432] The light-emitting device of one embodiment of the present invention can be applied to the display portion 7000.

[0433] 8A can be operated using operation switches provided on the housing 7101 and a separate remote control 7111. Alternatively, the display unit 7000 may be provided with a touch sensor, and operation may be performed by touching the display unit 7000 with a finger or the like. The remote control 7111 may have a display unit that displays information output from the remote control 7111. Using operation keys or a touch panel provided on the remote control 7111, it is possible to operate the channel and volume, and to control the video displayed on the display unit 7000.

[0434] The television device 7100 is configured to include a receiver, a modem, and the like. The receiver can receive general television broadcasts. In addition, by connecting to a wired or wireless communication network via the modem, it is possible to perform one-way (from sender to receiver) or two-way (between sender and receiver, or between receivers, etc.) information communication.

[0435] 8B shows an example of a laptop personal computer 7200. The laptop personal computer 7200 includes a housing 7211, a keyboard 7212, a pointing device 7213, and an external connection port 7214. The housing 7211 includes a display portion 7000.

[0436] The light-emitting device of one embodiment of the present invention can be applied to the display portion 7000.

[0437] 8C and 8D show an example of digital signage.

[0438] 8C includes a housing 7301, a display unit 7000, and a speaker 7303. The digital signage 7300 may further include an LED lamp, operation keys (including a power switch or an operation switch), a connection terminal, various sensors, a microphone, and the like.

[0439] 8D shows a digital signage 7400 attached to a cylindrical pole 7401. The digital signage 7400 has a display unit 7000 provided along the curved surface of the pole 7401.

[0440] 8C and 8D, the light-emitting device of one embodiment of the present invention can be applied to the display portion 7000.

[0441] The larger the display unit 7000, the more information can be provided at one time. Also, the larger the display unit 7000, the more easily it will attract people's attention, which can increase the advertising effectiveness of, for example, advertisements.

[0442] Applying a touch panel to the display unit 7000 is preferable because it not only displays images or videos on the display unit 7000 but also allows the user to intuitively operate it. Furthermore, when used to provide information such as route information or traffic information, intuitive operation can improve usability.

[0443] 8C and 8D, it is preferable that digital signage 7300 or digital signage 7400 can wirelessly link with information terminal 7311 or information terminal 7411, such as a smartphone carried by a user. For example, advertising information displayed on display unit 7000 can be displayed on the screen of information terminal 7311 or information terminal 7411. Furthermore, by operating information terminal 7311 or information terminal 7411, the display on display unit 7000 can be switched.

[0444] Furthermore, it is also possible to cause the digital signage 7300 or the digital signage 7400 to execute a game using the screen of the information terminal 7311 or the information terminal 7411 as an operation means (controller), thereby allowing an unspecified number of users to simultaneously participate in and enjoy the game.

[0445] 9A to 9F show an example of a portable information terminal having a flexible display portion 7001. FIG.

[0446] The display portion 7001 is manufactured using the light-emitting device of one embodiment of the present invention. For example, a light-emitting device that can be bent with a curvature radius of 0.01 mm to 150 mm can be used. The display portion 7001 may be provided with a touch sensor, and a mobile information terminal can be operated by touching the display portion 7001 with a finger or the like.

[0447] 9A to 9C show an example of a foldable mobile information terminal. Fig. 9A shows the mobile information terminal 7600 in an unfolded state, Fig. 9B shows a state in the process of changing from either the unfolded state or the folded state, and Fig. 9C shows the mobile information terminal 7600 in a folded state. The mobile information terminal 7600 has excellent portability in the folded state, and has excellent viewability in the unfolded state due to its seamless, wide display area.

[0448] The display portion 7001 is supported by three housings 7601 connected by hinges 7602. By bending the two housings 7601 via the hinges 7602, the portable information terminal 7600 can be reversibly transformed from an unfolded state to a folded state.

[0449] 9D and 9E show an example of a foldable mobile information terminal. FIG. 9D shows a mobile information terminal 7650 folded so that the display portion 7001 faces inward, and FIG. 9E shows a mobile information terminal 7650 folded so that the display portion 7001 faces outward. The mobile information terminal 7650 has a display portion 7001 and a non-display portion 7651. When the mobile information terminal 7650 is not in use, folding the mobile information terminal 7650 so that the display portion 7001 faces inward can prevent the display portion 7001 from getting dirty or scratched.

[0450] 9F shows an example of a wristwatch-type portable information terminal. The portable information terminal 7800 includes a band 7801, a display portion 7001, an input / output terminal 7802, and operation buttons 7803. The band 7801 functions as a housing. The portable information terminal 7800 can be equipped with a flexible battery 7805. The battery 7805 may be disposed overlapping the display portion 7001 or the band 7801, for example.

[0451] The band 7801, the display portion 7001, and the battery 7805 are flexible, so that the portable information terminal 7800 can be easily bent into a desired shape.

[0452] The operation button 7803 can be provided with various functions, such as time setting, power on / off operation, wireless communication on / off operation, silent mode activation / deactivation, power saving mode activation / deactivation, etc. For example, the functions of the operation button 7803 can be freely set by an operating system incorporated in the mobile information terminal 7800.

[0453] Furthermore, by touching an icon 7804 displayed on the display unit 7001 with a finger or the like, an application can be started.

[0454] The mobile information terminal 7800 is also capable of performing standardized short-range wireless communication. For example, hands-free conversation is possible by communicating with a wirelessly enabled headset.

[0455] The portable information terminal 7800 may also have an input / output terminal 7802. When the portable information terminal 7800 has the input / output terminal 7802, data can be directly exchanged with another information terminal through a connector. Charging can also be performed through the input / output terminal 7802. Note that the charging operation of the portable information terminal exemplified in this embodiment may be performed by contactless power transmission without using an input / output terminal.

[0456] 10A shows the appearance of an automobile 9700. FIG. 10B shows a driver's seat of the automobile 9700. The automobile 9700 includes a body 9701, wheels 9702, a windshield 9703, a light 9704, a fog lamp 9705, and the like. The light-emitting device of one embodiment of the present invention can be used for a display portion of the automobile 9700. For example, the light-emitting device of one embodiment of the present invention can be provided in the display portions 9710 to 9715 shown in FIG. 10B. Alternatively, the light-emitting device of one embodiment of the present invention may be used for the light 9704 or the fog lamp 9705.

[0457] The display portion 9710 and the display portion 9711 are display devices provided on the windshield of an automobile. The light-emitting device of one embodiment of the present invention can have a so-called see-through state, in which the other side can be seen through, by forming electrodes and wirings using a light-transmitting conductive material. If the display portion 9710 or the display portion 9711 is see-through, the display portion 9710 or the display portion 9711 does not obstruct visibility even when driving the automobile 9700. Therefore, the light-emitting device of one embodiment of the present invention can be installed on the windshield of the automobile 9700. When a transistor or the like is provided to drive the light-emitting device, a light-transmitting transistor such as an organic transistor using an organic semiconductor material or a transistor using an oxide semiconductor is preferably used.

[0458] The display unit 9712 is a display device provided on a pillar. For example, by displaying an image from an imaging means provided on the vehicle body on the display unit 9712, the view blocked by the pillar can be complemented. The display unit 9713 is a display device provided on the dashboard. For example, by displaying an image from an imaging means provided on the vehicle body on the display unit 9713, the view blocked by the dashboard can be complemented. That is, by displaying an image from an imaging means provided on the outside of the vehicle, blind spots can be complemented and safety can be improved. Furthermore, by displaying an image that complements the invisible parts, safety can be confirmed more naturally and without discomfort.

[0459] FIG. 10C shows the interior of a vehicle equipped with bench seats for the driver's seat and passenger seat. Display unit 9721 is a display device provided in the door. For example, by displaying an image from an imaging means provided in the vehicle body on display unit 9721, it is possible to complement the view blocked by the door. Display unit 9722 is a display device provided in the steering wheel. Display unit 9723 is a display device provided in the center of the seat surface of the bench seat. Note that a display device can be installed on the seat surface or backrest, and the display device can be used as a seat heater using the heat generated by the display device as a heat source.

[0460] The display unit 9714, the display unit 9715, or the display unit 9722 can provide various information by displaying navigation information, a speedometer, a tachometer, mileage, a fuel gauge, gear status, air conditioning settings, and the like. The display items and layout displayed on the display units can be changed as appropriate to suit the user's preferences. The above information can also be displayed on the display units 9710 to 9713, the display unit 9721, and the display unit 9723. The display units 9710 to 9715 and the display units 9721 to 9723 can also be used as lighting devices. The display units 9710 to 9715 and the display units 9721 to 9723 can also be used as heating devices.

[0461] Furthermore, since the electronic device of one embodiment of the present invention includes the light-emitting device of one embodiment of the present invention as a light source, the electronic device has high emission efficiency and low driving voltage. For example, the light-emitting device of one embodiment of the present invention can be used as a light source that emits visible light or near-infrared light. The light-emitting device of one embodiment of the present invention can also be used as a light source for a lighting device.

[0462] FIG. 11A shows a biometric authentication device for finger veins, and includes a housing 911, a light source 912, and a detection stage 913. By placing a finger on the detection stage 913, the shape of the veins can be imaged. A light source 912 that emits near-infrared light is provided above the detection stage 913, and an imaging device 914 is provided below it. The detection stage 913 is made of a material that transmits near-infrared light, and the near-infrared light that is irradiated from the light source 912 and transmitted through the finger can be imaged by the imaging device 914. An optical system may be provided between the detection stage 913 and the imaging device 914. The above device configuration can also be used in a biometric authentication device for palm veins.

[0463] The light-emitting device of one embodiment of the present invention can be used as the light source 912. The light-emitting device of one embodiment of the present invention can be installed in a curved shape and can uniformly irradiate an object with light. A light-emitting device that emits near-infrared light having the strongest peak intensity in a wavelength range of 700 nm to 1200 nm is particularly preferable. For example, the position of veins can be detected by receiving light that has passed through a finger or a palm and imaging it. This function can be used for biometric authentication. Furthermore, by combining the light-emitting device with a global shutter system, highly accurate sensing is possible even when the object is moving.

[0464] 11B , the light source 912 may have a plurality of light-emitting units, such as light-emitting units 915, 916, and 917. The light-emitting units 915, 916, and 917 may emit light at different wavelengths. Furthermore, each light-emitting unit may emit light at a different timing. Therefore, by changing either or both of the wavelength and angle of the emitted light, different images can be captured consecutively, and multiple images can be used for authentication, thereby achieving high security.

[0465] FIG. 11C illustrates a biometric authentication device for palm veins, which includes a housing 921, an operation button 922, a detection unit 923, and a light source 924 that emits near-infrared light. The shape of palm veins can be recognized by holding a hand over the detection unit 923. A personal identification number or the like can also be input using the operation button. A light source 924 is disposed around the detection unit 923 and irradiates a target object (hand). Reflected light from the target object is incident on the detection unit 923. A light-emitting device according to one embodiment of the present invention can be used for the light source 924. An imaging device 925 is disposed directly below the detection unit 923 and can capture an image of the target object (the entire image of the hand). Note that an optical system may be provided between the detection unit 923 and the imaging device 925. The above-described device configuration can also be used for a biometric authentication device for finger veins.

[0466] FIG. 11D shows a nondestructive inspection device including a housing 931, an operation panel 932, a conveying mechanism 933, a monitor 934, a detection unit 935, and a light source 938 that emits near-infrared light. The light-emitting device of one embodiment of the present invention can be used for the light source 938. An inspected member 936 is conveyed by the conveying mechanism 933 to a position directly below the detection unit 935. The inspected member 936 is irradiated with near-infrared light from the light source 938, and the transmitted light is captured by an imaging device 937 provided in the detection unit 935. The captured image is displayed on a monitor 934. The inspected member is then conveyed to the exit of the housing 931, where defective products are sorted and collected. By capturing images using near-infrared light, defective elements such as defects and foreign matter inside the inspected member can be detected nondestructively and quickly.

[0467] FIG. 11E illustrates a mobile phone including a housing 981, a display portion 982, operation buttons 983, an external connection port 984, a speaker 985, a microphone 986, a first camera 987, and a second camera 988. The mobile phone includes a touch sensor in the display portion 982. The housing 981 and the display portion 982 are flexible. Any operation, such as making a call or inputting text, can be performed by touching the display portion 982 with a finger or a stylus. The first camera 987 can capture a visible light image, and the second camera 988 can capture an infrared light image (near-infrared light image). The mobile phone or the display portion 982 illustrated in FIG. 11E may include a light-emitting device of one embodiment of the present invention.

[0468] This embodiment mode can be combined with other embodiment modes as appropriate. [Example]

[0469] In this example, a light-emitting device according to one embodiment of the present invention was fabricated and evaluated, and the results are described.

[0470] In this example, Device 1, which is a light-emitting device of one embodiment of the present invention, and Comparative Device 2 for comparison were fabricated and evaluated. The results are described below.

[0471] The structures of the two light-emitting devices used in this example are shown in Figure 12, and their specific configurations are shown in Table 1. The chemical formulas of the materials used in this example are shown below.

[0472] [Table 1]

[0473] [ka]

[0474] <Fabrication of light-emitting devices> 12 , the light-emitting device shown in this example has a structure in which a first electrode 801 is formed on a substrate 800, a hole injection layer 811, a first hole transport layer 812a, a first buffer layer 816, a second hole transport layer 812b, a light-emitting layer 813, an electron transport layer 814, and an electron injection layer 815 are sequentially stacked on the first electrode 801 as an EL layer 802, a second electrode 803 is formed on the electron injection layer 815, and a second buffer layer 805 is formed on the second electrode 803. The light-emitting device shown in this example is a top-emission light-emitting device in which light is emitted to the second electrode 803 side.

[0475] First, a first electrode 801 was formed on a substrate 800. The electrode area was 4 mm 2 The dimensions of the substrate 800 were 2 mm x 2 mm. A glass substrate was used as the substrate 800. The first electrode 801 was formed by depositing an alloy of silver, palladium, and copper (Ag-Pd-Cu, APC) by sputtering to a thickness of 100 nm, and then depositing an indium tin oxide containing silicon oxide (ITSO) by sputtering to a thickness of 10 nm. In this example, the first electrode 801 functions as an anode.

[0476] Here, as a pretreatment, the surface of the substrate was washed with water, baked at 200°C for 1 hour, and then subjected to UV ozone treatment for 370 seconds. -4The 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.

[0477] Next, a hole injection layer 811 was formed on the first electrode 801 .

[0478] The hole injection layer 811 of the device 1 was formed by evaporating the -4 After reducing the pressure to 10 Pa, N,N-bis(4-cyclohexylphenyl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviated as dchPAF) and an electron acceptor material (OCHD-001) were co-evaporated to a thickness of 10 nm in a weight ratio of dchPAF:OCHD-001 = 1:0.1. OCHD-001 is an organic compound containing fluorine and has acceptor properties.

[0479] The hole injection layer 811 of the comparative device 2 was formed by evaporating the film in a vacuum deposition apparatus for 10 -4 After reducing the pressure to 10 Pa, N-(1,1'-biphenyl-4-yl)-9,9-dimethyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9H-fluoren-2-amine (abbreviation: PCBBiF) and OCHD-001 were co-evaporated to a weight ratio of PCBBiF:OCHD-001 = 1:0.1 and a film thickness of 10 nm.

[0480] In both Device 1 and Comparative Device 2, the weight percent concentration of OCHD-001 in hole injection layer 811 is 10 wt %, and the volume percent concentration is 7.5 vol %.

[0481] Next, a first hole transport layer 812 a was formed on the hole injection layer 811 .

[0482] First hole transport layer 812a of device 1 was formed by vapor deposition of dchPAF to a thickness of 145 nm.

[0483] The first hole transport layer 812a of the comparative device 2 was formed by vapor deposition of PCBBiF to a thickness of 125 nm.

[0484] As will be described later, dchPAF and PCBBiF have different refractive indices, and therefore the optical path length (refractive index × film thickness) of the first hole transport layer 812a was made uniform by changing the film thickness of the first hole transport layer 812a.

[0485] Next, a first buffer layer 816 was formed on the first hole transport layer 812a. The first buffer layer 816 was formed by vapor deposition of OCHD-001 to a thickness of 1 nm.

[0486] Next, a second hole transport layer 812b was formed on the first buffer layer 816. The second hole transport layer 812b was formed by evaporating N-(1,1′-biphenyl-2-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9,9′-spirobi[9H-fluorene]-4-amine (abbreviation: oFBiSF) to a thickness of 20 nm.

[0487] Next, the light-emitting layer 813 was formed on the second hole-transporting layer 812b. The light-emitting layer 813 was formed using 8-(1,1'-biphenyl-4-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8BP-4mDBtPBfpm) as a host material (also referred to as a first host material), 9-(2-naphthyl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: βNCCP) as an assist material (also referred to as a second host material), and a guest material ( The phosphorescent material was [2-d3-methyl-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: [Ir(ppy)2(mbfpypy-d3)]) and the weight ratio was 8BP-4mDBtPBfpm:βNCCP:[Ir(ppy)2(mbfpypy-d3)] = 0.6:0.4:0.1, and the film thickness was 40 nm.

[0488] Next, an electron transport layer 814 was formed on the light-emitting layer 813. The electron transport layer 814 was formed by evaporating 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm) to a thickness of 25 nm and evaporating 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBPhen) to a thickness of 10 nm.

[0489] Next, electron injection layer 815 was formed on electron transport layer 814. Electron injection layer 815 was formed by vapor deposition of lithium fluoride (LiF) to a thickness of 1 nm.

[0490] Next, a second electrode 803 was formed on the electron injection layer 815. The second electrode 803 was formed by co-evaporation of silver (Ag) and magnesium (Mg) so that the volume ratio of Ag:Mg was 1:0.1 and the film thickness was 15 nm. In this example, the second electrode 803 functioned as a cathode.

[0491] Next, a second buffer layer 805 was formed on the second electrode 803. The second buffer layer 805 was formed by vapor deposition of 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) to a film thickness of 70 nm.

[0492] Through the above steps, a light-emitting device was formed on the substrate 800. Note that in all of the vapor deposition steps in the above-described manufacturing method, a vapor deposition method using resistance heating was used.

[0493] The fabricated light-emitting device was sealed with another substrate (not shown). When sealing using another substrate (not shown), another substrate (not shown) coated with an adhesive that hardens when exposed to ultraviolet light was fixed on substrate 800 in a nitrogen atmosphere glove box, and the substrates were bonded together so that the adhesive adhered to the periphery of the light-emitting device formed on substrate 800. During sealing, 365 nm ultraviolet light was applied at 6 J / cm. 2The adhesive was solidified by irradiation and then stabilized by heat treatment at 80°C for 1 hour.

[0494] Figure 13 shows the refractive index of the low-refractive-index material (dchPAF) used for hole injection layer 811 and first hole transport layer 812a, as well as that of PCBBiF, a comparative material. Measurements were performed using a spectroscopic ellipsometer (M-2000U, manufactured by J.A. Woollam Japan). A sample was prepared by depositing a 50-nm-thick film of the material on a quartz substrate by vacuum deposition. The figure also shows the refractive index (n Ordinary) for ordinary rays and the refractive index (n Extraordinary) for extraordinary rays. Measurements revealed that the ordinary refractive index of the layer made of dchPAF at a wavelength of 633 nm was 1.65, while the ordinary refractive index of the layer made of PCBBiF at a wavelength of 633 nm was 1.81. Furthermore, the ordinary refractive index of the layer made of dchPAF at a wavelength of 530 nm was 1.68, while the ordinary refractive index of the layer made of PCBBiF at a wavelength of 530 nm was 1.86. The layer made of oFBiSF used in second hole transport layer 812b had an ordinary refractive index of 1.73 for light with a wavelength of 633 nm and an ordinary refractive index of 1.76 for light with a wavelength of 530 nm. In other words, dchPAF used in device 1 is an organic compound with a refractive index lower than that of oFBiSF.

[0495] Furthermore, the LUMO level of OCHD-001 calculated from the results of cyclic voltammetry (CV) measurements was -5.27 eV when N,N-dimethylformamide (DMF) was used as the solvent and -5.40 eV when chloroform was used as the solvent. Furthermore, when DMF was used as the solvent, the HOMO level of dchPAF was -5.36 eV, the HOMO level of PCBBiF was -5.36 eV, and the HOMO level of oFBiSF was -5.50 eV. From these results, it can be said that OCHD-001 exhibits electron-accepting properties toward dchPAF, PCBBiF, and oFBiSF. Furthermore, it can be said that oFBiSF is an organic compound with a lower HOMO level than dchPAF and PCBBiF. The CV measurement was performed using an electrochemical analyzer (manufactured by BAS Inc., model number: ALS model 600A or 600C) to measure a solution in which the material to be measured was dissolved in a solvent.

[0496] The hole mobility of dchPAF and PCBBiF was measured using impedance spectroscopy (IS). Specifically, a 500 nm thick layer of dchPAF or PCBBiF was sandwiched between a pair of electrodes made of indium tin oxide (ITSO) and aluminum. The area in contact with ITSO contained OCHD-001 at a concentration of 7 vol%, and the area in contact with aluminum contained molybdenum oxide (MoO3) at a concentration of 17 vol%.

[0497] As a result of the measurement, the square root of the electric field strength (V / cm) was 200 (V / cm) 1 / 2 When , the hole mobility of dchPAF is 7.0 × 10 -4 cm 2 / Vs, and the hole mobility of PCBBiF is 5.6×10 -4 cm 2 / Vs. Thus, dchPAF is a hole-transporting material that can be used in the light-emitting device of one embodiment of the present invention, and is a monoamine compound having high hole mobility.

[0498] <Operating characteristics of light-emitting devices> The operating characteristics of the light-emitting device fabricated in this example were measured using a spectroradiometer (SR-UL1R, manufactured by Topcon Corporation) at room temperature.

[0499] Figure 14 shows the luminance vs. current density characteristics of the light-emitting device. Figure 15 shows the current efficiency vs. luminance characteristics of the light-emitting device. Figure 16 shows the current density vs. voltage characteristics of the light-emitting device. Figure 17 shows the external quantum efficiency vs. luminance characteristics of the light-emitting device. Table 2 also shows the luminance vs. current density characteristics of the light-emitting device at 1000 cd / m 2 The main initial characteristic values ​​of the light-emitting device in the vicinity of 1000 sq. m are shown. Note that the external quantum efficiency shown in Fig. 17 and Table 2, as well as the power efficiency and energy efficiency shown in Table 2, are true values ​​obtained by taking into account the viewing angle characteristics and measuring the light emission from the front direction.

[0500] [Table 2]

[0501] 14 to 17 and Table 2, it was found that Device 1 had higher luminous efficiency than Comparative Device 2. Furthermore, it was found that although Device 1 had a thicker first hole transport layer 812a than Comparative Device 2, the driving voltage was almost the same. This suggests that the use of the first buffer layer 816 was able to suppress the increase in driving voltage.

[0502] The dchPAF used in Device 1 has a lower refractive index than the PCBBiF used in Comparative Device 2. This resulted in Device 1 exhibiting higher luminous efficiency than Comparative Device 2.

[0503] The concentration of OCHD-001 is low in the hole injection layer 811. In other words, the refractive indexes of the hole injection layer 811 and the first hole transport layer 812a can be considered to be almost the same. This reduces the refractive index difference and increases the light extraction efficiency.

[0504] The ratio of the number of carbon atoms forming bonds with sp3 hybrid orbitals to the total number of carbon atoms in dchPAF is 38.5%. Even though a material with such a large number of unsaturated bonds is used, almost no adverse effects on the various properties of Device 1 (such as luminous efficiency and reliability, which will be described later) were observed.

[0505] In addition, the light-emitting device has a luminance of 1000 cd / m 2 The emission spectra around 529 nm are shown in Figure 18. As shown in Figure 18, Device 1 exhibited an emission spectrum with a maximum peak around 529 nm, which is due to the emission of [Ir(ppy)2(mbfpypy-d3)] contained in the light-emitting layer 813. Similarly, Comparative Device 2 exhibited an emission spectrum with a maximum peak around 528 nm.

[0506] Next, a reliability test was conducted on the light-emitting device. The results of the reliability test are shown in Figure 19. In Figure 19, the vertical axis represents normalized luminance (%) when the initial luminance is taken as 100%, and the horizontal axis represents driving time (h). The reliability test was conducted at room temperature with a current density of 50 mA / cm 2 The light-emitting device was driven by setting

[0507] The initial luminance of Device 1 is 59100 cd / m 2 and the initial luminance of Device 2 is 54600 cd / m 2 The luminance of Device 1 after 100 hours was 86% of the initial luminance, and the luminance of Comparative Device 2 after 100 hours was 85% of the initial luminance. These results demonstrate that Device 1 has higher reliability than Comparative Device 2.

[0508] From the above, it was found that Device 1 had higher luminous efficiency and higher reliability than Comparative Device 2. [Example]

[0509] In this example, a light-emitting device according to one embodiment of the present invention was fabricated and evaluated, and the results are described.

[0510] In this example, a device 3 which is a light-emitting device of one embodiment of the present invention and a comparative device 4 for comparison were fabricated and evaluated. The results are described.

[0511] The structures of the two light-emitting devices used in this example are shown in FIG. 12, and their specific configurations are shown in Table 3. The chemical formulas of the materials used in this example are shown below. Note that the light-emitting device of this example did not have the second buffer layer 805 shown in FIG. 12. The light-emitting device shown in this example is a bottom-emission type light-emitting device in which light is emitted to the first electrode 801 side.

[0512] [Table 3]

[0513] [ka]

[0514] <Fabrication of light-emitting devices> In the method for producing the light-emitting device of this example, the same parts as those in the method for producing device 1 produced in Example 1 can be referred to in Example 1, and therefore description thereof will be omitted.

[0515] The first electrode 801 of the light-emitting device of this example was formed by depositing ITSO to a film thickness of 110 nm by sputtering.

[0516] In this example, device 3 was provided with a first buffer layer 816, while comparative device 4 was not.

[0517] The second hole transport layer 812b of the light-emitting device of this example was formed by vapor-depositing N-(1,1'-biphenyl-2-yl)-N-(3'',5',5''-tri-tert-butyl-1,1':3',1''-terphenyl-4-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPoFBi-04) to a thickness of 40 nm.

[0518] The light-emitting layer 813 of the light-emitting device of this example was formed by co-evaporation using 11-(4-[1,1'-diphenyl]-4-yl-6-phenyl-1,3,5-triazin-2-yl)-11,12-dihydro-12-phenyl-indolo[2,3-a]carbazole (abbreviation: BP-Icz(II)Tzn) as a host material, 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP) as an assist material, and [Ir(ppy)2(mbfpypy-d3)] as a guest material in a weight ratio of BP-Icz(II)Tzn:PCCP:[Ir(ppy)2(mbfpypy-d3)]=0.5:0.5:0.1 and with a thickness of 40 nm.

[0519] The electron transport layer 814 of the light-emitting device of this example was formed by evaporating 2-[3′-(9,9-dimethyl-9H-fluoren-2-yl)-1,1′-biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn) to a thickness of 10 nm, and co-evaporating 2-[3-(2,6-dimethyl-3-pyridyl)-5-(9-phenanthryl)phenyl)-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn) and 8-quinolinolato-lithium (abbreviation: Liq) in a weight ratio of 1:1 to a thickness of 25 nm.

[0520] The second electrode 803 of the light-emitting device of this example was formed by depositing aluminum to a thickness of 200 nm by vapor deposition.

[0521] The refractive index of the low-refractive index material (mmtBumTPoFBi-04) used in the second hole transport layer 812b is shown in Figure 20. A spectroscopic ellipsometer (M-2000U manufactured by J.A. Woollam Japan) was used for the measurement. A film of approximately 50 nm of material deposited by vacuum deposition on a quartz substrate was used as the sample. The figure also shows the refractive index of ordinary rays (n Ordinary) and extraordinary rays (n Extraordinary). The measurement results showed that the layer made of mmtBumTPoFBi-04 had an ordinary refractive index of 1.66 for light with a wavelength of 633 nm. The layer made of mmtBumTPoFBi-04 also had an ordinary refractive index of 1.69 for light with a wavelength of 530 nm. As shown in Example 1, the layer made of dchPAF had an ordinary refractive index of 1.65 for light with a wavelength of 633 nm and an ordinary refractive index of 1.68 for light with a wavelength of 530 nm. That is, dchPAF used in Device 3 is an organic compound having a lower refractive index than mmtBumTPoFBi-04.

[0522] Furthermore, as shown in Example 1, the LUMO level of OCHD-001 calculated from the results of CV measurement was -5.27 eV when DMF was used as the solvent and -5.40 eV when chloroform was used as the solvent. Furthermore, when DMF was used as the solvent, the HOMO level of dchPAF was -5.36 eV, and the HOMO level of mmtBumTPoFBi-04 was -5.42 eV. From these results, it can be said that mmtBumTPoFBi-04 is an organic compound with a lower HOMO level than dchPAF. It can also be said that OCHD-001 exhibits electron-accepting properties toward dchPAF and mmtBumTPoFBi-04.

[0523] <Operating characteristics of light-emitting devices> The operating characteristics of the light-emitting device fabricated in this example were measured using a spectroradiometer (SR-UL1R, manufactured by Topcon Corporation) at room temperature.

[0524] Figure 21 shows the luminance-current density characteristics of the light-emitting device. Figure 22 shows the current efficiency-luminance characteristics of the light-emitting device. Figure 23 shows the current density-voltage characteristics of the light-emitting device. Figure 24 shows the external quantum efficiency-luminance characteristics of the light-emitting device.

[0525] Table 4 shows 1000cd / m 2 The main initial characteristic values ​​of the light-emitting device in the vicinity are shown.

[0526] [Table 4]

[0527] In addition, the light-emitting device has a luminance of 1000 cd / m 2 The emission spectra around 527 nm are shown in Figure 25. As shown in Figure 25, Device 3 and Comparative Device 4 exhibited emission spectra with a maximum peak around 527 nm, which is due to the emission of [Ir(ppy)(mbfpypy-d)] contained in the light-emitting layer 813.

[0528] As shown in FIGS. 21 to 24 and Table 4, it was found that Device 3 exhibited luminous efficiency equivalent to that of Comparative Device 4, and had a lower driving voltage. Therefore, it was found that Device 3 exhibited higher power efficiency than Comparative Device 4, and was driven with lower power consumption. Device 3 differs from Comparative Device 4 in that it has a first buffer layer 816. This shows that Device 3 was able to have a lower driving voltage than Comparative Device 4 because it has the first buffer layer 816.

[0529] In addition, the ratio of the number of carbon atoms forming bonds with sp3 hybrid orbitals to the total number of carbon atoms in mmtBumTPoFBi-04 is 26.3%. Even though a material with such a large number of unsaturated bonds is used, almost no adverse effects on the various characteristics (such as luminous efficiency) of device 3 having first buffer layer 816 were observed.

[0530] (Reference example) This reference example describes a method for synthesizing an organic compound that can be used as the first organic compound described in Embodiment 1. These organic compounds are examples of materials with low refractive indexes and hole-transporting properties. Specifically, as shown in Table 5, these organic compounds all have an ordinary refractive index of 1.50 to 1.75 in the wavelength range of blue light emission (455 nm to 465 nm), an ordinary refractive index of 1.48 to 1.73 in the wavelength range of green light emission (525 nm to 535 nm), and an ordinary refractive index of 1.45 to 1.70 in the wavelength range of 633 nm, which is typically used for measuring refractive index. Furthermore, as shown in Table 5, the ratio of the number of carbon atoms forming bonds with sp3 hybrid orbitals to the total number of carbon atoms in each of these organic compounds is 23% to 55%.

[0531] [Table 5]

[0532] First, a method for synthesizing N,N-bis(4-cyclohexylphenyl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: dchPAF), represented by the following structural formula (100), will be described.

[0533] [ka]

[0534] A three-neck flask was charged with 10.6 g (51 mmol) of 9,9-dimethyl-9H-fluoren-2-amine, 18.2 g (76 mmol) of 4-cyclohexyl-1-bromobenzene, 21.9 g (228 mmol) of sodium tert-butoxide, and 255 mL of xylene. The flask was degassed under reduced pressure and then purged with nitrogen. The mixture was heated to approximately 50°C with stirring. Then, 370 mg (1.0 mmol) of allyl palladium chloride dimer (II) (abbreviation: [(Allyl)PdCl]2) and 1660 mg (4.0 mmol) of di-tert-butyl(1-methyl-2,2-diphenylcyclopropyl)phosphine (abbreviation: cBRIDP®) were added, and the mixture was heated at 120°C for approximately 5 hours. The flask was then returned to approximately 60°C, and approximately 4 mL of water was added to precipitate a solid. The precipitated solid was filtered off. The filtrate was concentrated, and the resulting solution was purified by silica gel column chromatography. The resulting solution was concentrated to obtain a concentrated toluene solution. This toluene solution was added dropwise to ethanol to cause reprecipitation. The precipitate was filtered at approximately 10°C, and the resulting solid was dried under reduced pressure at approximately 80°C to obtain 10.1 g of the target white solid in a 40% yield. The synthesis scheme of dchPAF is shown below.

[0535] [ka]

[0536] Nuclear magnetic resonance spectroscopy ( 1 The results of the analysis by H-NMR are shown below. These results demonstrate that dchPAF was successfully synthesized.

[0537] 1H-NMR.δ(CDCl3):7.60(d,1H,J=7.5Hz),7.53(d,1H,J=8.0Hz),7.37(d,2H,J=7 .5Hz),7.29(td,1H,J=7.5Hz,1.0Hz),7.23(td,1H,J=7.5Hz,1.0Hz),7.19(d,1H ,J=1.5Hz),7.06(m,8H),6.97(dd,1H,J=8.0Hz,1.5Hz),2.41-2.51(brm,2H),1. 79-1.95(m,8H),1.70-1.77(m,2H),1.33-1.45(brm,14H),1.19-1.30(brm,2H).

[0538] Similarly, organic compounds represented by the following structural formulas (101) to (111) were synthesized.

[0539] [ka]

[0540] [ka]

[0541] Nuclear magnetic resonance spectroscopy of these organic compounds ( 1 The analytical results by H-NMR are shown below. For some organic compounds, the glass transition temperatures are also shown.

[0542] Results for N-[(3',5'-ditertiarybutyl)-1,1'-biphenyl-4-yl]-N-(4-cyclohexylphenyl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBuBichPAF) represented by structural formula (101).

[0543] 1H-NMR.δ(CDCl3):7.63(d,1H,J=7.5Hz),7.57(d,1H,J=8.0Hz),7.44-7.49(m,2H) ,7.37-7.42(m,4H),7.31(td,1H,J=7.5Hz,2.0Hz),7.23-7.27(m,2H),7.15-7.19( m,2H),7.08-7.14(m,4H),7.05(dd,1H,J=8.0Hz,2.0Hz),2.43-2.53(brm,1H),1. 81-1.96(m,4H),1.75(d,1H,J=12.5Hz),1.32-1.48(m,28H),1.20-1.31(brm,1H).

[0544] The glass transition temperature of mmtBuBichPAF represented by structural formula (101) was 102°C.

[0545] Results for N-(3,3'',5,5''-tetra-tert-butyl-1,1':3',1''-terphenyl-5'-yl)-N-(4-cyclohexylphenyl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPchPAF) represented by structural formula (102).

[0546] 1 H-NMR.δ(CDCl3)=7.63(d,J=6.6Hz,1H),7.58(d,J=8.1Hz,1H),7.42-7.37(m,4H),7.36-7.09(m,14H),2.55-2.39(m,1H),1.98-1.20(m,51H).

[0547] The glass transition temperature of mmtBumTPchPAF represented by structural formula (102) was 124°C.

[0548] Results for N-[(3,3',5'-tert-butyl)-1,1'-biphenyl-5-yl]-N-(4-cyclohexylphenyl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumBichPAF) represented by structural formula (103).

[0549] 1H-NMR.δ(CDCl3):7.63(d,1H,J=7.5Hz),7.56(d,1H,J=8.5Hz),7.37-40(m, 2H),7.27-7.32(m,4H),7.22-7.25(m,1H),7.16-7.19(brm,2H),7.08-7.15 (m,4H),7.02-7.06(m,2H),2.43-2.51(brm,1H),1.80-1.93(brm,4H),1.71 -1.77(brm,1H),1.36-1.46(brm,10H),1.33(s,18H),1.22-1.30(brm,10H).

[0550] The glass transition temperature of mmtBumBichPAF represented by structural formula (103) was 103°C.

[0551] Results for N-(1,1'-biphenyl-2-yl)-N-[(3,3',5'-tri-tert-butyl)-1,1'-biphenyl-5-yl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumBioFBi) represented by structural formula (104).

[0552] 1 H-NMR.δ(CDCl3):7.57(d,1H,J=7.5Hz),7.40-7.47(m,2H),7.32-7.39(m,4H),7.27-7.31(m,2H ),7.27-7.24(m,5H),6.94-7.09(m,6H),6.83(brs,2H),1.33(s,18H),1.32(s,6H),1.20(s,9H).

[0553] The glass transition temperature of mmtBumBioFBi represented by structural formula (104) was 102°C.

[0554] Results for N-(4-tert-butylphenyl)-N-(3,3'',5,5''-tetra-tert-butyl-1,1':3',1''-terphenyl-5'-yl)-9,9,-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPtBuPAF) represented by structural formula (105).

[0555] 1 H-NMR.δ(CDCl3):7.64(d,1H,J=7.5Hz),7.59(d,1H,J=8.0Hz),7.38-7.43(m,4H),7.29-7.36(m,8H) ,7.24-7.28(m,3H),7.19(d,2H,J=8.5Hz),7.13(dd,1H,J=1.5Hz,8.0Hz),1.47(s,6H),1.32(s,45H).

[0556] The glass transition temperature of mmtBumTPtBuPAF represented by structural formula (105) was 123°C.

[0557] Results for N-(1,1'-biphenyl-2-yl)-N-(3,3'',5',5''-tetra-tert-butyl-1,1':3',1''-terphenyl-5-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPoFBi-02) represented by structural formula (106).

[0558] 1 H-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).

[0559] The glass transition temperature of mmtBumTPoFBi-02 represented by structural formula (106) was 126°C.

[0560] Results for N-(4-cyclohexylphenyl)-N-(3,3'',5',5''-tetra-tert-butyl-1,1':3',1''-terphenyl-5-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPchPAF-02) represented by structural formula (107).

[0561] 1 H-NMR.δ(CDCl3):7.62(d,1H,J=7.5Hz),7.56(d,1H,J=8.0Hz),7.50(dd,1H,J=1.7Hz),7.4 6-7.47(m,2H),7.43(dd,1H,J=1.7Hz),7.37-7.39(m,3H),7.29-7.32(m,2H),7.23-7.25(m ,2H),7.20(dd,1H,J=1.7Hz),7.09-7.14(m,5H),7.05(dd,1H,J=2.3Hz),2.46(brm,1H),1. 83-1.88(m,4H),1.73-1.75(brm,1H),1.42(s,6H),1.38(s,9H),1.36(s,18H),1.29(s,9H).

[0562] The glass transition temperature of mmtBumTPchPAF-02 represented by structural formula (107) was 127°C.

[0563] Results for N-(1,1'-biphenyl-2-yl)-N-(3'',5',5''-tri-tert-butyl-1,1':3',1''-terphenyl-5-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPoFBi-03) represented by structural formula (108).

[0564] 1 H-NMR.δ(CDCl3):7.55(d,1H,J=7.4Hz),7.50(dd,1H,J=1.7Hz),7.42-7.43(m,3H),7.27-7.39(m,10H),7.18-7.25(m,4H),7.00-7.12 (m,4H),6.97(dd,1H,J=6.3Hz,1.7Hz),6.93(d,1H,J=1.7Hz),6.82(dd,1H,J=7.3Hz,2.3Hz),1.37(s,9H),1.36(s,18H),1.29(s,6H).

[0565] Results for N-(4-cyclohexylphenyl)-N-(3'',5',5''-tri-tert-butyl-1,1':3',1''-terphenyl-5-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPchPAF-03) represented by structural formula (109).

[0566] 1 H-NMR.δ(CDCl3):7.62(d,1H,J=7.5Hz),7.56(d,1H,J=8.6Hz),7.51(dd,1H,J=1.7 Hz),7.48(dd,1H,J=1.7Hz),7.46(dd,1H,J=1.7Hz),7.42(dd,1H,J=1.7Hz),7.37-7 .39(m,4H),7.27-7.33(m,2H),7.23-7.25(m,2H),7.05-7.13(m,7H),2.46(brm,1H) ),1.83-1.90(m,4H),1.73-1.75(brm,1H),1.41(s,6H),1.37(s,9H),1.35(s,18H).

[0567] Results for N-(1,1'-biphenyl-2-yl)-N-(3'',5',5''-tri-tert-butyl-1,1':3',1''-terphenyl-4-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPoFBi-04) represented by structural formula (110).

[0568] 1 H-NMR.δ(CDCl3):7.54-7.56(m,1H),7.53(dd,1H,J=1.7Hz),7.50(dd,1H,J=1.7Hz),7.27-7.47(m,12H),7.23(dd,1H,J=6.3Hz,1.2Hz ),7.18-7.19(m,2H),7.08-7.00(m,5H),6.88(d,1H,J=1.7Hz)6.77(dd,1H,J=8.0Hz,2.3Hz),1.42(s,9H),1.39(s,18H),1.29(s,6H).

[0569] Results for N-(4-cyclohexylphenyl)-N-(3'',5',5''-tri-tert-butyl-1,1':3',1''-terphenyl-4-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPchPAF-04) represented by structural formula (111).

[0570] 1 H-NMR.δ(CDCl3):7.63(d,1H,J=7.5Hz),7.52-7.59(m,7H),7.44-7.45(m,4H),7.39(d,1H,J=7.4Hz),7.31(dd,1H,J=7.4Hz),7.19(d,2H,J=6.6Hz) ,7.12(m,4H),7.07(d,1H,J=9.7Hz),2.48(brm,1H),1.84-1.93(brm,4H) ,1.74-1.76(brm,1H),1.43(s,18H),1.39(brm,19H)1.24-1.30(brm,1H). [Explanation of symbols]

[0571] 101: first electrode, 102: second electrode, 103a: EL layer, 103b: EL layer, 103c: EL layer, 103: EL layer, 104: charge generation layer, 105: layer containing an organic compound, 109: buffer layer, 111: hole injection layer, 112a: first hole transport layer, 112b: second hole transport layer, 113: light emitting layer, 114: electron transport layer, 115: electron injection layer, 116: hole transport layer, 117: active layer, 118: electron transport layer, 119: buffer layer, 201: substrate, 202a: insulating layer, 202b: insulating layer, 202: insulating layer, 203B: light emitting device, 203G: light emitting device 203R: light emitting device, 203W: light emitting device, 204: insulating layer, 205: substrate, 206B: color filter, 206G: color filter, 206R: color filter, 207: space, 208: adhesive layer, 209: black matrix, 210: transistor, 211: first electrode, 212G: conductive layer, 212R: conductive layer, 213B: EL layer, 213G: EL layer, 213R: EL layer, 213: EL layer, 215: second electrode, 220B: optical path, 220G: optical path, 220R: optical path, 301: first substrate, 302: pixel section, 303: circuit section , 304a: circuit section, 304b: circuit section, 305: sealing material, 306: second substrate, 307: routing wiring, 308: FPC, 309: transistor, 310: transistor, 311: transistor, 312: transistor, 313: first electrode, 314: insulating layer, 315: EL layer, 316: second electrode, 317: organic EL device, 318: space, 320: transistor, 321: conductive layer, 322a: conductive layer, 322b: conductive layer, 323: conductive layer, 324: insulating layer, 325: insulating layer, 326: insulating layer, 327i: channel formation region, 327n: low resistance Region, 327: semiconductor layer, 328: insulating layer, 330: transistor, 331: conductive layer, 332a: conductive layer, 332b: conductive layer, 333: conductive layer, 334: insulating layer, 335: insulating layer, 337: semiconductor layer, 338: insulating layer, 401: first electrode, 402: EL layer, 403: second electrode, 405: insulating layer, 406: conductive layer, 407: adhesive layer, 416: conductive layer, 420: substrate, 422: adhesive layer, 423: barrier layer, 424: insulating layer, 450: organic EL device, 490a: substrate, 490b: substrate, 490c: barrier layer, 500A: display device, 500B: display device,500C: display device, 500D: display device, 500E: display device, 510: light receiving device, 511: pixel electrode, 512: buffer layer, 513: active layer, 514: buffer layer, 515: common electrode, 520: finger, 521: light, 521B: light, 521G: light, 521R: light, 522: light, 531: transistor, 532B: transistor, 532G: transistor, 532: transistor, 533: insulating layer, 534: insulating layer, 551: substrate, 552: substrate, 553: adhesive layer, 554: light shielding layer, 555: functional layer, 580SR: light receiving and emitting device, 590B: light emitting device 590G: light-emitting device, 590IR: light-emitting device, 590R: light-emitting device, 590: light-emitting device, 591B: pixel electrode, 591G: pixel electrode, 591: pixel electrode, 593B: light-emitting layer, 593G: light-emitting layer, 593R: light-emitting layer, 593: light-emitting layer, 595: protective layer, 800: substrate, 801: first electrode, 802: EL layer, 803: second electrode, 805: second buffer layer, 811: hole injection layer, 812a: first hole transport layer, 812b: second hole transport layer, 813: light-emitting layer, 814: electron transport layer, 815: electron injection layer, 816: first buffer layer , 911: Housing, 912: Light source, 913: Detection stage, 914: Imaging device, 915: Light emitting unit, 916: Light emitting unit, 917: Light emitting unit, 921: Housing, 922: Operation button, 923: Detection unit, 924: Light source, 925: Imaging device, 931: Housing, 932: Operation panel, 933: Conveying mechanism, 934: Monitor, 935: Detection unit, 936: Inspected member, 937: Imaging device, 938: Light source, 981: Housing, 982: Display unit, 983: Operation button, 984: External connection port, 985: Speaker, 986: Microphone, 987: First camera, 988: Second camera, 70 00: display unit, 7001: display unit, 7100: television device, 7101: housing, 7103: stand, 7111: remote control device, 7200: notebook personal computer, 7211: housing, 7212: keyboard, 7213: pointing device, 7214: external connection port, 7300: digital signage, 7301: housing, 7303: speaker, 7311: information terminal device, 7400: digital signage, 7401: pillar, 7411: information terminal device, 7600: mobile information terminal, 7601: housing, 7602: hinge, 7650: mobile information terminal,7651: Non-display section, 7800: Portable information terminal, 7801: Band, 7802: Input / output terminal, 7803: Operation button, 7804: Icon, 7805: Battery, 9700: Automobile, 9701: Body, 9702: Wheel, 9703: Windshield, 9704: Light, 9705: Fog lamp, 9710: Display section, 9711: Display section, 9712: Display section, 9713: Display section, 9714: Display section, 9715: Display section, 9721: Display section, 9722: Display section, 9723: Display section,

Claims

1. a first electrode; a first layer on the first electrode; a second layer on the first layer; and a light-emitting layer on the second layer; and a second electrode on the light-emitting layer, the first layer comprises a first organic compound; the second layer comprises a second organic compound; The first organic compound is 10 －６ cm ２ / Vs or more, the refractive index of the layer made of the first organic compound at light having a wavelength of 633 nm is 1.45 or more and 1.70 or less; The LUMO level of the second organic compound is −5.0 eV or less.

2. a first electrode; a first layer on the first electrode; a second layer on the first layer; and a light-emitting layer on the second layer; and a second electrode on the light-emitting layer, the first layer comprises a first organic compound; the second layer comprises a second organic compound; The first organic compound is 10 －６ cm ２ / Vs or more, the refractive index of the layer made of the first organic compound at a wavelength of 455 nm or more and 465 nm or less is 1.50 or more and 1.75 or less; The LUMO level of the second organic compound is −5.0 eV or less.

3. a first electrode; a first layer on the first electrode; a second layer on the first layer; and a light-emitting layer on the second layer; and a second electrode on the light-emitting layer, the first layer comprises a first organic compound; the second layer comprises a second organic compound; The first organic compound is 10 －６ cm ２ / Vs or more, the refractive index of the layer made of the first organic compound at a wavelength of 525 nm or more and 535 nm or less is 1.48 or more and 1.73 or less; The LUMO level of the second organic compound is −5.0 eV or less.

4. In any one of claims 1 to 3, a third layer between the second layer and the light-emitting layer; the third layer comprises a third organic compound; a HOMO level of the third organic compound is lower than a HOMO level of the first organic compound;

5. a first electrode; a first layer on the first electrode; a second layer on the first layer; and a third layer on the second layer; and a light-emitting layer on the third layer; and a second electrode on the light-emitting layer, the first layer comprises a first organic compound; the second layer comprises a second organic compound; the third layer comprises a third organic compound; The first organic compound is 10 －６ cm ２ / Vs or more, the refractive index of the layer made of the first organic compound at light having a wavelength of 633 nm is 1.45 or more and 1.70 or less; the LUMO level of the second organic compound is −5.0 eV or less; A light-emitting device, wherein the refractive index of the layer made of the first organic compound is lower than the refractive index of the layer made of the third organic compound.

6. a first electrode; a first layer on the first electrode; a second layer on the first layer; and a third layer on the second layer; and a light-emitting layer on the third layer; and a second electrode on the light-emitting layer, the first layer comprises a first organic compound; the second layer comprises a second organic compound; the third layer comprises a third organic compound; The first organic compound is 10 －６ cm ２ / Vs or more, the refractive index of the layer made of the first organic compound at a wavelength of 455 nm or more and 465 nm or less is 1.50 or more and 1.75 or less; the LUMO level of the second organic compound is −5.0 eV or less; A light-emitting device, wherein the refractive index of the layer made of the first organic compound is lower than the refractive index of the layer made of the third organic compound.

7. a first electrode; a first layer on the first electrode; a second layer on the first layer; and a third layer on the second layer; and a light-emitting layer on the third layer; and a second electrode on the light-emitting layer, the first layer comprises a first organic compound; the second layer comprises a second organic compound; the third layer comprises a third organic compound; The first organic compound is 10 －６ cm ２ / Vs or more, the refractive index of the layer made of the first organic compound at a wavelength of 525 nm or more and 535 nm or less is 1.48 or more and 1.73 or less; the LUMO level of the second organic compound is −5.0 eV or less; A light-emitting device, wherein the refractive index of the layer made of the first organic compound is lower than the refractive index of the layer made of the third organic compound.

8. In any one of claims 5 to 7, a difference in refractive index between the layer made of the first organic compound for light having a wavelength of 633 nm and the layer made of the third organic compound for light having a wavelength of 633 nm being 0.05 or more;

9. In any one of claims 5 to 8, a HOMO level of the third organic compound is lower than a HOMO level of the first organic compound;

10. In any one of claims 1 to 9, A light-emitting device, wherein the molecular weight of the first organic compound is 650 or more and 1,200 or less.

11. A light-emitting device according to any one of claims 1 to 10; a transistor and / or a substrate;

12. The light emitting device according to claim 11; A light emitting module having at least one of a connector and an integrated circuit.

13. The light emitting device according to claim 11; An electronic device having at least one of an antenna, a battery, a housing, a camera, a speaker, a microphone, and an operation button.

14. A light-emitting device according to any one of claims 1 to 10; A lighting device having at least one of a housing, a cover, and a support base.

Images