Light emitting apparatus, display apparatus, electroinic apparatus, and illumination apparatus

Abstract

The present invention provides a light emitting device having a high luminous efficiency. The light emitting device comprises: a first electrode; a second electrode; and an EL layer located between the first and second electrodes. The EL layer has at least a light emitting layer, a first layer, a second layer, and a third layer. The first layer is located between the first electrode and the light emitting layer. The third layer is located between the first layer and the light emitting layer. The second layer is located between the first layer and the third layer. The first layer contains a first organic compound. The second layer contains a second organic compound. The third layer contains a third organic compound. The ordinary light refractive index of the second organic compound is higher than that of the first organic compound and that of the third organic compound.

Description

Light-emitting device, display device, electronic device, and lighting device

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

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

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

[0004] Furthermore, these light-emitting devices can have a continuous light-emitting layer formed two-dimensionally, enabling them to emit light in a planar form. This is a feature that is difficult to obtain with point light sources such as incandescent lamps or LEDs, or linear light sources such as fluorescent lamps, making them highly useful as planar light sources for lighting and other applications.

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

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

[0007] US Patent Application Publication No. 2020 / 0176692

[0008] Yutaka Noguchi and two others, "Orientational Polarization Phenomenon of Polar Molecules and Interface Characteristics of Organic Thin Film Devices," Journal of the Vacuum Society of Japan, 2015, Vol. 58, No. 3

[0009] An object of one embodiment of the present invention is to provide a light-emitting device with high emission efficiency, or to provide a light-emitting device, a light-emitting apparatus, an electronic device, a display device, or an electronic device with low power consumption.

[0010] The present invention is intended to solve any one of the above problems.

[0011] One aspect of the present invention is a light-emitting device including a first light-emitting device and a first color conversion layer. The first light-emitting device includes a first electrode, a second electrode, and an EL layer located between the first electrode and the second electrode. The EL layer includes at least a light-emitting layer, a first layer, a second layer, and a third layer. The first layer is located between the first electrode and the light-emitting layer. The third layer is located between the first layer and the light-emitting layer. The second layer is located between the first layer and the third layer. The first layer is a first organic compound, the second layer including a second organic compound, the third layer including a third organic compound, the ordinary refractive index of the second organic compound at any wavelength of 450 nm or more and 650 nm or less being higher than the ordinary refractive index of the first organic compound at said wavelength and the ordinary refractive index of the third organic compound at said wavelength, the first color conversion layer including a first substance that absorbs light and emits light, and the first color conversion layer being located on an optical path along which light emitted by the first light-emitting device is emitted to the outside of the light-emitting device.

[0012] Another aspect of the present invention is a light-emitting device including a first light-emitting device and a first color conversion layer. The first light-emitting device includes a first electrode, a second electrode, and an EL layer located between the first electrode and the second electrode. The EL layer includes at least a light-emitting layer, a first layer, a second layer, and a third layer. The first layer is located between the first electrode and the light-emitting layer. The third layer is located between the first layer and the light-emitting layer. The second layer is located between the first layer and the third layer. a first layer containing a first organic compound, the second layer containing a second organic compound, the third layer containing a third organic compound, the ordinary refractive index of the second organic compound at any wavelength of 455 nm or more and 465 nm or less being higher than the ordinary refractive index of the first organic compound at said wavelength and the ordinary refractive index of the third organic compound at said wavelength, the first color conversion layer containing a first substance that absorbs light and emits light, and the first color conversion layer being located on an optical path along which light emitted by the first light-emitting device is emitted to the outside of the light-emitting device.

[0013] Another embodiment of the present invention is a light-emitting device including a first light-emitting device and a first color conversion layer. The first light-emitting device includes a first electrode, a second electrode, and an EL layer located between the first electrode and the second electrode. The EL layer includes at least a light-emitting layer, a first layer, a second layer, and a third layer. The first layer is located between the first electrode and the light-emitting layer. The third layer is located between the first layer and the light-emitting layer. The second layer is located between the first layer and the third layer. the first layer contains a first organic compound, the second layer contains a second organic compound, the third layer contains a third organic compound, the second organic compound has an ordinary refractive index at 633 nm that is higher than the ordinary refractive index at 633 nm of the first organic compound and the ordinary refractive index at 633 nm of the third organic compound, the first color conversion layer contains a first substance that absorbs light and emits light, and the first color conversion layer is located on an optical path along which light emitted by the first light-emitting device exits the light-emitting device.

[0014] Another embodiment of the present invention is a light-emitting device including a first light-emitting device and a first color conversion layer. The first light-emitting device includes a first electrode, a second electrode, and an EL layer located between the first electrode and the second electrode. The EL layer includes at least a light-emitting layer, a first layer, a second layer, and a third layer. The first layer is located between the first electrode and the light-emitting layer. The third layer is located between the first layer and the light-emitting layer. The second layer is located between the first layer and the third layer. The light-emitting layer has a peak wavelength of a light-emitting material that emits light at a wavelength λ; the first layer includes a first organic compound; the second layer includes a second organic compound; the third layer includes a third organic compound; the ordinary refractive index of the second organic compound at the wavelength λ is higher than the ordinary refractive index of the first organic compound at the wavelength λ and the ordinary refractive index of the third organic compound at the wavelength λ; the first color conversion layer includes a first substance that absorbs light and emits light; and the first color conversion layer is located on an optical path along which light emitted by the first light-emitting device exits the light-emitting device.

[0015] Another embodiment of the present invention is a light-emitting device having the above structure, in which a difference between a HOMO level of the first organic compound and a HOMO level of the third organic compound is 0.2 eV or less.

[0016] Another embodiment of the present invention is a light-emitting device having any of the above structures, in which the first organic compound and the third organic compound are the same organic compound.

[0017] Another embodiment of the present invention is a light-emitting device having any of the above structures, wherein a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.2 eV or less.

[0018] Another embodiment of the present invention is a light-emitting device having the above structure, in which the third layer does not contain fluorine.

[0019] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the first to third layers each have a thickness of 25 nm to 70 nm.

[0020] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the second layer is thicker than the first layer and the third layer.

[0021] Another embodiment of the present invention is a light-emitting device having the above structure, in which the first layer and the second layer are in contact with each other, and the second layer and the third layer are in contact with each other.

[0022] Alternatively, another embodiment of the present invention is a light-emitting device having the above-described configuration, wherein a difference between the ordinary refractive index at the wavelength λ of the second organic compound and the ordinary refractive index at the wavelength λ of the first organic compound, and a difference between the ordinary refractive index at the wavelength λ of the second organic compound and the ordinary refractive index at the wavelength λ of the third organic compound are each 0.2 or more and less than 0.5.

[0023] Another embodiment of the present invention is a light-emitting device having the above structure, wherein a difference in ordinary refractive index at the wavelength λ between the first organic compound and the third organic compound is 0.1 eV or less.

[0024] Another embodiment of the present invention is a light-emitting device having the above-described structure, wherein the product of the film thickness of the second layer and the ordinary refractive index of the second organic compound at the wavelength λ is 70% to 130% of the wavelength λ / 4.

[0025] Another embodiment of the present invention is a light-emitting device having any of the above structures, in which the first electrode includes a reflective electrode.

[0026] Another embodiment of the present invention is a light-emitting device having the above structure, in which a value obtained by subtracting the GSP (mV / nm) of the second hole-transport layer from the GSP (mV / nm) of the third hole-transport layer is −10 (mV / nm) or more.

[0027] Another embodiment of the present invention is a light-emitting device having the above structure, in which a value obtained by subtracting the GSP (mV / nm) of the first hole-transport layer from the GSP (mV / nm) of the second hole-transport layer is −10 (mV / nm) or more.

[0028] Another embodiment of the present invention is a light-emitting device having the above structure, in which the GSP (mV / nm) of the third hole-transport layer is larger than the GSP (mV / nm) of the second hole-transport layer.

[0029] Another embodiment of the present invention is a light-emitting device having the above structure, in which the GSP (mV / nm) of the third hole-transport layer is larger than the GSP (mV / nm) of the first hole-transport layer.

[0030] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the GSP (mV / nm) of the second hole-transport layer is larger than the GSP (mV / nm) of the first hole-transport layer.

[0031] Another embodiment of the present invention is a light-emitting device having any of the above structures, in which the first organic compound and the third organic compound are different organic compounds.

[0032] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the first color conversion layer has a refractive index of 1.40 to 2.10 for light with a wavelength of 455 nm to 465 nm.

[0033] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the first color conversion layer has a refractive index of 1.80 to 2.00 for light with a wavelength of 455 nm to 465 nm.

[0034] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the first color conversion layer further includes a resin, and the refractive index of the resin for light with a wavelength of 455 nm to 465 nm is 1.40 to 2.10.

[0035] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the resin has a refractive index of 1.80 to 2.00 with respect to light having a wavelength of 455 nm to 465 nm.

[0036] Another embodiment of the present invention is a light-emitting device having the above structure, further including a first layer containing a fourth organic compound between the light-emitting device and the first color conversion layer, and a refractive index of the first layer with respect to light having a wavelength of 455 nm to 465 nm is 1.40 to 2.10.

[0037] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the first layer has a refractive index of 1.70 to 2.00 with respect to light having a wavelength of 455 nm to 465 nm.

[0038] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the first substance is a quantum dot.

[0039] Alternatively, another aspect of the present invention is a light-emitting device having the above-described configuration, wherein the light-emitting device further includes a second light-emitting device, a third light-emitting device, and a second color conversion layer, wherein the second light-emitting device and the third light-emitting device have the same structure as the first light-emitting device, the second color conversion layer includes a second substance that absorbs light and emits light, the peak wavelength of the emission spectrum of the first substance is different from the peak wavelength of the emission spectrum of the second substance, and the second color conversion layer is located on an optical path along which light emitted by the second light-emitting device exits the light-emitting device.

[0040] Another embodiment of the present invention is a light-emitting device having the above structure, in which the second substance is a quantum dot.

[0041] Another embodiment of the present invention is a light-emitting device having the above structure, in which the first substance has an emission spectrum having a peak wavelength in the range of 500 nm to 600 nm, and the second substance has an emission spectrum having a peak wavelength in the range of 600 nm to 750 nm.

[0042] Alternatively, another aspect of the present invention is a light-emitting device having the above-described configuration, wherein the light-emitting device further includes a fourth light-emitting device and a third color conversion layer, the fourth light-emitting device having a structure similar to that of the first light-emitting device, the third color conversion layer including a third substance that absorbs light and emits light, the third substance having an emission spectrum with a peak wavelength in the range of 560 nm to 610 nm, and the third color conversion layer being located on an optical path along which light emitted by the fourth light-emitting device exits the light-emitting device.

[0043] Another embodiment of the present invention is a light-emitting device having any of the above structures, in which the third substance contains a rare earth element.

[0044] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the rare earth element is one or more selected from the group consisting of europium, cerium, and yttrium.

[0045] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the third substance is a quantum dot.

[0046] Another embodiment of the present invention is a light-emitting device having any of the above structures, in which an emission spectrum obtained from the third color conversion layer has two peaks.

[0047] Another embodiment of the present invention is a light-emitting device having the above structure, in which the light emitted from the third color conversion layer is white light.

[0048] Another embodiment of the present invention is a light-emitting device having any of the above structures, in which the first light-emitting device emits blue light.

[0049] Another embodiment of the present invention is an electronic device including the above-described light-emitting device, a sensor, an operation button, and a speaker or a microphone.

[0050] Another embodiment of the present invention is a display device including the above light-emitting device and a transistor or a substrate.

[0051] Another embodiment of the present invention is a lighting device including the above-described light-emitting device and a housing.

[0052] In this specification, the term "light-emitting device" includes an image display device using a light-emitting device. The term "light-emitting device" may also include a module in which a connector, such as an anisotropic conductive film or a TCP (Tape Carrier Package), is attached to a light-emitting device, a module in which a printed wiring board is provided at the end of a TCP, or a module in which an IC (integrated circuit) is directly mounted on a light-emitting device using a COG (Chip On Glass) method. Furthermore, lighting fixtures and the like may have a light-emitting device.

[0053] According to one embodiment of the present invention, a light-emitting device with high emission efficiency or a light-emitting device, a light-emitting apparatus, an electronic device, a display device, or an electronic device with low power consumption can be provided.

[0054] Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. Note that effects other than these will become apparent from the description in the specification, drawings, claims, etc., and it is possible to extract other effects from the description in the specification, drawings, claims, etc.

[0055] FIGS. 1A, 1B, 1C, and 1D are schematic diagrams of light-emitting devices. FIGS. 2A and 2B are diagrams illustrating an active matrix light-emitting device. FIGS. 3A and 3B are diagrams illustrating an active matrix light-emitting device. FIG. 4 is a diagram illustrating an active matrix light-emitting device. FIGS. 5A and 5B are diagrams illustrating a passive matrix light-emitting device. FIGS. 6A and 6B are diagrams illustrating a lighting device. FIGS. 7A, 7B1, 7B2, and 7C are diagrams illustrating electronic devices. FIGS. 8A, 8B, and 8C are diagrams illustrating electronic devices. FIG. 9 is a diagram illustrating a lighting device. FIG. 10 is a diagram illustrating a lighting device. FIG. 11 is a diagram illustrating an in-vehicle display device and a lighting device. FIGS. 12A and 12B are diagrams illustrating electronic devices. FIGS. 13A, 13B, and 13C are diagrams illustrating electronic devices. FIGS. 14A to 14D are diagrams illustrating configuration examples of display devices. FIGS. 15A to 15F are diagrams illustrating examples of methods for manufacturing display devices. 16A to 16F are diagrams showing an example of a method for fabricating a display device. FIG. 17 is a diagram showing the refractive indexes of PCBDBtBB-02 and mmtBumTPoFBi-02. FIG. 18 is a diagram showing the luminance-current density characteristics of Light-Emitting Device 1, Comparative Light-Emitting Device 1, and Comparative Light-Emitting Device 2. FIG. 19 is a diagram showing the luminance-voltage characteristics of Light-Emitting Device 1, Comparative Light-Emitting Device 1, and Comparative Light-Emitting Device 2. FIG. 20 is a diagram showing the current efficiency-luminance characteristics of Light-Emitting Device 1, Comparative Light-Emitting Device 1, and Comparative Light-Emitting Device 2. FIG. 21 is a diagram showing the current density-voltage characteristics of Light-Emitting Device 1, Comparative Light-Emitting Device 1, and Comparative Light-Emitting Device 2. FIG. 22 is a diagram showing the blue index-luminance characteristics of Light-Emitting Device 1, Comparative Light-Emitting Device 1, and Comparative Light-Emitting Device 2. FIG. 23 is a diagram showing the emission spectra of Light-Emitting Device 1, Comparative Light-Emitting Device 1, and Comparative Light-Emitting Device 2. FIG. 24 is a diagram showing the refractive indexes of BBA(βN2)B-03 and mmtBuBioFBi. Fig. 25 is a graph showing the luminance-current density characteristics of the light-emitting device 10 and the comparative light-emitting device 10. Fig. 26 is a graph showing the luminance-voltage characteristics of the light-emitting device 10 and the comparative light-emitting device 10. Fig. 27 is a graph showing the current efficiency-luminance characteristics of the light-emitting device 10 and the comparative light-emitting device 10.FIG. 28 is a graph showing the current density-voltage characteristics of light-emitting device 10 and comparative light-emitting device 10. FIG. 29 is a graph showing the blue index-current density characteristics of light-emitting device 10 and comparative light-emitting device 10. FIG. 30 is a graph showing the emission spectra of light-emitting device 10 and comparative light-emitting device 10. FIG. 31 is a graph showing the viewing angle characteristics of light-emitting device 10 and comparative light-emitting device 10. FIG. 32 is a graph showing the relative luminance-time change characteristics of light-emitting device 10 and comparative light-emitting device 10. FIG. 33 is a graph showing the luminance-current density characteristics of light-emitting device 20. FIG. 34 is a graph showing the luminance-voltage characteristics of light-emitting device 20. FIG. 35 is a graph showing the current efficiency-luminance characteristics of light-emitting device 20. FIG. 36 is a graph showing the current density-voltage characteristics of light-emitting device 20. FIG. 37 is a graph showing the blue index-luminance characteristics of light-emitting device 20. FIG. 38 is a graph showing the emission spectrum of light-emitting device 20. FIG. 39 is a graph showing the normalized luminance-time change characteristics of light-emitting device 20. FIG. 40 is a graph showing the luminance-current density characteristics of light-emitting device 30. FIG. 41 shows the luminance-voltage characteristics of light-emitting device 30. FIG. 42 shows the current efficiency-luminance characteristics of light-emitting device 30. FIG. 43 shows the current density-voltage characteristics of light-emitting device 30. FIG. 44 shows the blue index-current density characteristics of light-emitting device 30. FIG. 45 shows the emission spectrum of light-emitting device 30. FIG. 46 shows the relative luminance-time change characteristics of light-emitting device 30. FIGS. 47A and 47B show the refractive indexes of BBA(βN2)B-03, mmtBuBioFBi, and mmtBumTPoFBi-04. FIG. 48 shows the luminance-current density characteristics of light-emitting device 40, light-emitting device 41, and comparative light-emitting device 40. FIG. 49 shows the current efficiency-luminance characteristics of light-emitting device 40, light-emitting device 41, and comparative light-emitting device 40. FIG. 50 shows the luminance-voltage characteristics of light-emitting device 40, light-emitting device 41, and comparative light-emitting device 40. 51 is a graph showing the current density-voltage characteristics of the light-emitting device 40, the light-emitting device 41, and the comparative light-emitting device 40. FIG. 52 is a graph showing the blue index-luminance characteristics of the light-emitting device 40, the light-emitting device 41, and the comparative light-emitting device 40.FIG. 53 is a graph showing the power efficiency-luminance characteristics of light-emitting device 40, light-emitting device 41, and comparative light-emitting device 40. FIG. 54 is a graph showing the emission spectra of light-emitting device 40, light-emitting device 41, and comparative light-emitting device 40. FIG. 55 is a graph showing the normalized luminance-time change characteristics of light-emitting device 40, light-emitting device 41, and comparative light-emitting device 40. FIG. 56 is a graph showing the luminance-current density characteristics of comparative light-emitting device 50 and light-emitting device 50. FIG. 57 is a graph showing the luminance-voltage characteristics of comparative light-emitting device 50 and light-emitting device 50. FIG. 58 is a graph showing the current efficiency-luminance characteristics of comparative light-emitting device 50 and light-emitting device 50. FIG. 59 is a graph showing the current-voltage characteristics of comparative light-emitting device 50 and light-emitting device 50. FIG. 60 is a graph showing the power efficiency-luminance characteristics of comparative light-emitting device 50 and light-emitting device 50. FIG. 61 is a graph showing the emission spectra of comparative light-emitting device 50 and light-emitting device 50. 62A and 62B are diagrams showing the refractive indexes of mmtBumTPoFBi-04, PCBBiPDBt-02, and mmtBuBiFF. FIGS. 63A to 63C are conceptual diagrams of a light-emitting device. FIGS. 64A to 64C are conceptual diagrams of a light-emitting device. FIGS. 65A to 65C are conceptual diagrams of a light-emitting device. FIGS. 66A and 66B are conceptual diagrams of a passive matrix light-emitting device. FIG. 67 is a diagram showing the emission spectrum used in the calculation. FIG. 68 is a diagram showing the results of calculating the relationship between the refractive index of the color conversion layer (QD layer) and the amount of light reaching the color conversion layer. FIG. 69 is a diagram showing an example of the configuration of a display device.

[0056] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it will be readily understood by those skilled in the art that various changes in form and details can be made without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the description of the embodiments shown below.

[0057] When light is incident on a material with optical anisotropy, the light in the vibration plane parallel to the optical axis is called extraordinary light (ray), and the light in the vibration plane perpendicular to the optical axis is called ordinary light (ray). However, the refractive index of the material for ordinary light and extraordinary light may differ. In such cases, anisotropy analysis can be performed to separate the ordinary and extraordinary refractive indices and calculate each refractive index. In this specification, if the measured material has both an ordinary refractive index and an extraordinary refractive index, the ordinary refractive index will be used as the index. Furthermore, if these two types of refractive indexes do not exist, the term "refractive index" may simply be used.

[0058] 1A illustrates a light-emitting device according to one embodiment of the present invention. The light-emitting device illustrated in FIG. 1 includes a first electrode 101, a second electrode 102, and an EL layer 103. The EL layer includes at least a hole-transport layer 112 (a first hole-transport layer 112-1, a second hole-transport layer 112-2, and a third hole-transport layer 112-3) and a light-emitting layer 113. The light-emitting layer 113 includes at least a light-emitting material, and the hole-transport layer 112 is located between the light-emitting layer 113 and the first electrode 101. Note that the EL layer 103 may include a hole-injection layer 111, an electron-transport layer 114, an electron-injection layer 115, and the like, as illustrated, in addition to the above layers. The EL layer 103 may also include other functional layers, such as a carrier block layer, an exciton block layer, or an intermediate layer.

[0059] In one embodiment of the present invention, the first to third hole-transport layers 112-1 to 112-3 contain a first organic compound to a third organic compound, respectively, and the first to third organic compounds are contained in an amount of 80% or more in the first to third hole-transport layers.

[0060] In the light-emitting device of one embodiment of the present invention, the second organic compound has a higher refractive index than the first organic compound and the third organic compound, i.e., the second hole-transport layer 112-2 has a higher refractive index than the first hole-transport layer 112-1 and the third hole-transport layer 112-3.

[0061] In the light-emitting device of one embodiment of the present invention, light emitted from the light-emitting material is reflected at the interface of each hole-transport layer, so that more light can be reflected than when only a reflective electrode is used, thereby improving the external quantum efficiency. At the same time, the influence of surface plasmons and light absorption at the reflective electrode can be reduced, thereby reducing energy loss and enabling efficient light extraction.

[0062] In one embodiment of the present invention, the difference between the ordinary refractive index of the second organic compound and the ordinary refractive index of the first organic compound for light of a certain wavelength λ and the difference between the ordinary refractive index of the second organic compound and the ordinary refractive index of the third organic compound are each preferably 0.1 or more and less than 0.5, preferably 0.2 or more and less than 0.5, and more preferably 0.3 or more and less than 0.5. When these refractive index differences are in the above ranges, problems are unlikely to occur even if the hole-transport layer 112 having the same structure as that of this light-emitting device is applied to other light-emitting devices containing light-emitting materials that emit light of different wavelengths, and this is advantageous in terms of cost because it is not necessary to separately prepare the hole-transport layer 112 for each light-emitting color.

[0063] Note that, for light of wavelength λ, the difference between the ordinary refractive index of the second hole transport layer 112-2 and the ordinary refractive index of the first hole transport layer 112-1, and the difference between the ordinary refractive index of the second hole transport layer 112-2 and the ordinary refractive index of the third hole transport layer 112-3 are more preferably 0.2 or more and less than 0.5. The wavelength λ is 450 nm or more and 650 nm or less, or the entire range. When the light-emitting device emits light in the blue range, the wavelength λ is 455 nm to 465 nm or the entire range. Furthermore, the wavelength λ is preferably the emission peak wavelength of the light-emitting material. Note that the wavelength λ typically used as an index of refractive index is 633 nm. These values ​​may be used as indexes for the wavelength λ.

[0064] The refractive index of the first organic compound and the third organic compound at wavelength λ is preferably 1.40 or more and 1.75 or less. Specifically, the ordinary refractive index in the blue light emission region (455 nm or more and 465 nm or less) is preferably 1.40 or more and 1.75 or less, or the ordinary refractive index at 633 nm light, which is typically used for refractive index measurement, is preferably 1.40 or more and 1.70 or less. It is more preferable that the refractive index of the first hole transport layer and the third hole transport layer is within the above range. Furthermore, the difference in the ordinary refractive index at wavelength λ between the first organic compound and the third organic compound is preferably 0.1 or less.

[0065] The refractive index of the second organic compound for light of wavelength λ is preferably 1.75 or more, more preferably, the ordinary refractive index in the blue light emission region (455 nm to 465 nm) is 1.75 to 2.4, or the ordinary refractive index for light of 633 nm, which is typically used for measuring refractive index, is 1.75 to 2.30. It is more preferable that the refractive index of the second hole transport layer 112-2 be within the above range.

[0066] The difference in HOMO levels between the first organic compound and the third organic compound is preferably 0.2 eV or less, and more preferably 0.1 eV or less, to enhance hole transportability. The difference in HOMO levels between the second organic compound and each of the first and third organic compounds is preferably 0.2 eV or less, and more preferably 0.1 eV or less, to enhance hole transportability.

[0067] In the light-emitting device of one embodiment of the present invention, the thicknesses of the first hole-transport layer 112-1 to the third hole-transport layer 112-3 are preferably 25 nm to 70 nm. Note that in the light-emitting device of one embodiment of the present invention, the first hole-transport layer 112-1 and the third hole-transport layer 112-3 are each provided with a buffer layer such as a hole injection layer or an electron blocking layer in a direction away from the second hole-transport layer 112-2, thereby improving the light-emitting device characteristics. Therefore, the thickness of the second hole-transport layer 112-2 is preferably thicker than the thicknesses of the first hole-transport layer 112-1 and the third hole-transport layer 112-3. Furthermore, it is preferable that the product of the ordinary refractive index at a wavelength λ of the second hole-transport layer 112-2 and its thickness be 70% to 130% of λ / 4, in order to enhance light interference. By adopting such a configuration, light reflected at the interface between the third hole transport layer 112-3 and the second hole transport layer 112-2 and light reflected at the interface between the second hole transport layer 112-2 and the first hole transport layer 112-1 can be amplified by interference, making it possible to provide a more efficient light-emitting device.

[0068] In order to ensure reliability, it is preferable that the third hole transport layer 112-3 does not contain fluorine. In order to use the third hole transport layer 112-3 as a common hole transport layer for a display device having the three primary colors of red, green, and blue, it is undesirable for the optical interference that utilizes the refractive index step that enhances specific light to become too strong, so it is preferable that the first organic compound and the third organic compound do not contain fluorine, which has a low atomic refractive index.

[0069] The first hole transport layer 112-1 and the third hole transport layer 112-3 are formed using a material with a relatively low refractive index. However, there is usually a trade-off between high carrier transportability and a low refractive index. This is because the carrier transportability of organic compounds is largely due to the presence of unsaturated bonds, and organic compounds with many unsaturated bonds tend to have a high refractive index. Even if a material has a low refractive index, if the carrier transportability is low, problems such as an increase in driving voltage and a decrease in luminous efficiency or reliability due to a carrier imbalance can occur, making it impossible to obtain a light-emitting device with good characteristics. Furthermore, even if a material has sufficient carrier transportability and a low refractive index, if it has an unstable structure and therefore has problems with the glass transition point (Tg) or durability, it will be impossible to obtain a light-emitting device with good reliability.

[0070] Therefore, as an organic compound that can be used for the first hole transport layer 112-1 and the third hole transport layer 112-3, it is preferable to use a monoamine compound that has a first aromatic group, a second aromatic group, and a third aromatic group, and in which the first aromatic group, the second aromatic group, and the third aromatic group are bonded to the same nitrogen atom.

[0071] In the monoamine compound, the ratio of carbon atoms forming bonds via sp3 hybrid orbitals to the total number of carbon atoms in the molecule is preferably 23% or more and 55% or less, and １ The monoamine compound is preferably a compound in which the integral value of a signal below 4 ppm exceeds the integral value of a signal at 4 ppm or more when the compound is measured by H-NMR.

[0072] Furthermore, it is preferable that the monoamine compound has at least one fluorene skeleton, and that one or more of the first aromatic group, the second aromatic group, and the third aromatic group are fluorene skeletons. Since fluorenylamine has the effect of increasing the HOMO level, when three fluorenes are bonded to the nitrogen of the monoamine compound, the HOMO level may be significantly increased. In this case, the difference with the HOMO level of the surrounding material (e.g., the HOMO level of the material of the second hole transport layer 112-2) may become large, which may affect the driving voltage, reliability, etc. Therefore, it is more preferable that one or two of the first aromatic group, the second aromatic group, and the third aromatic group are fluorene skeletons.

[0073] Examples of the organic compound having the hole transporting property as described above include those having the following general formula (G ｈ１ 1) to (G ｈ１ 4) can be mentioned as an organic compound having a structure such as the one shown below.

[0074]

[0075] The general formula (G ｈ１ In 1), Ar １ , Ar ２ each independently represents a benzene ring or a substituent in which two or three benzene rings are bonded to each other, provided that Ar １ , Ar ２ one or both of Ar and Ar have one or more hydrocarbon groups having 1 to 12 carbon atoms in which carbon atoms form bonds only through sp3 hybrid orbitals, １ and Ar ２ The total number of carbon atoms contained in all the hydrocarbon groups bonded to Ar is 8 or more, and １ and Ar ２ The total number of carbon atoms contained in all the hydrocarbon groups bonded to either Ar or Ar is 6 or more. 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.

[0076]

[0077] The general formula (G ｈ１ In 2), m and r each independently represent 1 or 2, and m+r is 2 or 3. Each t independently represents an integer of 0 to 4, preferably 0. ５ represents either hydrogen or a hydrocarbon group having 1 to 3 carbon atoms. When m is 2, the types of substituents, the number of substituents, and the positions of bonds of the two phenylene groups may be the same or different, and when r is 2, the types of substituents, the number of substituents, and the positions of bonds of the two phenyl groups may be the same or different. When t is an integer of 2 to 4, a plurality of R ５ may be the same or different, R ５ Adjacent groups may be bonded to each other to form a ring.

[0078]

[0079] The general formula (G ｈ１ 2) and (G ｈ１ In 3), n and p each independently represent 1 or 2, and n+p and n+p each independently represent 2 or 3. Each s independently represents an integer of 0 to 4, preferably 0. ４ represents either hydrogen or a hydrocarbon group having 1 to 3 carbon atoms, and when n is 2, the types of substituents, the number of substituents, and the positions of bonds of the two phenylene groups may be the same or different, and when p is 2, the types of substituents, the number of substituents, and the positions of bonds of the two phenyl groups may be the same or different. ４ may be the same or different.

[0080]

[0081] The general formula (G ｈ１ 2) to (G ｈ１ 4) In R １０ ~R １４ and R ２０ ~R ２４Each independently represents hydrogen or a hydrocarbon group having 1 to 12 carbon atoms in which carbon atoms form bonds only through sp3 hybrid orbitals. １０ ~R １４ at least 3 of, and R ２０ ~R ２４ Preferably, at least 3 of R are hydrogen atoms. As the hydrocarbon group having 1 to 12 carbon atoms in which carbon atoms form bonds only through sp3 hybrid orbitals, a tert-butyl group and a cyclohexyl group are preferred. １０ ~R １４ and R ２０ ~R ２４ The total number of carbon atoms contained in R is 8 or more, and １０ ~R １４ or R ２０ ~R ２４ The total number of carbon atoms contained in either one of the above is 6 or more. ４ , R １０ ~R １４ and R ２０ ~R ２４ Adjacent groups may be bonded to each other to form a ring.

[0082] In addition, the above general formula (G ｈ１ 1) to (G ｈ１ In 4), each u independently represents an integer of 0 to 4, and is preferably 0. When u is an integer of 2 to 4, a plurality of R ３ may be the same or different. １ , R ２ and R ３ each independently represents an alkyl group having 1 to 4 carbon atoms; R １ and R ２ may be bonded to each other to form a ring.

[0083] Another preferred example of a material having hole transport properties that can be used for the first hole transport layer and the third hole transport layer 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 the nitrogen of the amine.

[0084] The first benzene ring may further have a substituted or unsubstituted phenyl group, preferably an unsubstituted phenyl group, and the second benzene ring or the third benzene ring may have a phenyl group substituted with an alkyl group.

[0085] It should be noted that hydrogen is not directly bonded to the carbon atoms at the first and third positions of two or more of the first to third benzene rings, preferably all of the benzene rings, but is bonded to any of the first to third benzene rings, the phenyl group substituted with an alkyl group, the at least three alkyl groups, and the nitrogen of the amine.

[0086] In addition, the arylamine compound preferably further has a second aromatic group.The second aromatic group is preferably an unsubstituted monocyclic ring or a group having substituted or unsubstituted fused rings of 3 or less, and more preferably a substituted or unsubstituted fused ring of 3 or less, and the fused ring is more preferably a group having a fused ring with 6 to 13 carbon atoms forming the ring, and even more preferably a group having a fluorene ring.In addition, the second aromatic group is preferably a dimethylfluorenyl group.

[0087] The arylamine compound preferably further comprises a third aromatic group, which is a group having one to three substituted or unsubstituted benzene rings.

[0088] The at least three alkyl groups and the alkyl group substituting the phenyl group are preferably chain alkyl groups having 2 to 5 carbon atoms. In particular, the alkyl group is preferably a branched chain alkyl group having 3 to 5 carbon atoms, and more preferably a t-butyl group.

[0089] Examples of the material having the hole transporting property as described above include the following (G ｈ２ 1) to (G ｈ２ Examples of the organic compound include those having the structure shown in 3).

[0090]

[0091] In addition, the above general formula (Gｈ２ In 1), Ar １０１ represents a substituted or unsubstituted benzene ring, or a substituent in which two or three substituted or unsubstituted benzene rings are bonded to each other.

[0092]

[0093] In addition, the above general formula (G ｈ２ In 2), x and y each independently represent 1 or 2, and x+y is 2 or 3. １０９ represents an alkyl group having 1 to 4 carbon atoms, and w represents an integer of 0 to 4. １４１ ~R １４５ each independently represents one of hydrogen, an alkyl group having 1 to 6 carbon atoms, and a cycloalkyl group having 5 to 12 carbon atoms. When w is 2 or more, multiple R １０９ may be the same or different. When x is 2, the type of substituents, the number of substituents, and the position of the bond of the two phenylene groups may be the same or different. When y is 2, the two R １４１ ~R １４５ The types and numbers of the substituents on the phenyl groups having the formula (I) may be the same or different.

[0094]

[0095] In addition, the above general formula (G ｈ２ 3) In 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.

[0096] In addition, the above general formula (G ｈ２ 1) to (G ｈ２ 3), and R １０６ , R １０７ and R １０８ Each independently represents an alkyl group having 1 to 4 carbon atoms, and v represents an integer of 0 to 4. When v is 2 or more, a plurality of R １０８ may be the same or different. １１１ ~R１１５ One of R is a substituent represented by the above general formula (g1), and the rest each independently represent one of hydrogen, an alkyl group having 1 to 6 carbon atoms, and a substituted or unsubstituted phenyl group. １２１ ~R １２５ One of R is a substituent represented by the above general formula (g2), and the rest each independently represent one of hydrogen, an alkyl group having 1 to 6 carbon atoms, and a phenyl group substituted with an alkyl group having 1 to 6 carbon atoms. １３１ ~R １３５ Each of R independently represents one of hydrogen, an alkyl group having 1 to 6 carbon atoms, and a phenyl group substituted with an alkyl group having 1 to 6 carbon atoms. １１１ ~R １１５ , R １２１ ~R １２５ and R １３１ ~R １３５ At least three of R are alkyl groups having 1 to 6 carbon atoms; １１１ ~R １１５ The number of substituted or unsubstituted phenyl groups in R １２１ ~R １２５ and R １３１ ~R １３５ In R, the number of phenyl groups substituted with alkyl groups having 1 to 6 carbon atoms is 1 or less. １１２ and R １１４ , 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.

[0097] The organic compound having hole transport properties as described above has an ordinary refractive index of 1.40 to 1.75 in the blue light-emitting region (455 nm to 465 nm) or an ordinary refractive index of 1.40 to 1.70 in the 633 nm light wavelength range typically used for measuring refractive index, and is an organic compound with good hole transport properties. It is also possible to obtain an organic compound with high Tg and good reliability. Because such organic compounds also have sufficient hole transport properties, they can be suitably used as materials for the first hole transport layer 112-1 and the third hole transport layer 112-3.

[0098] In addition, 1,1-bis{4-[bis(4-methylphenyl)amino]phenyl}cyclohexane (abbreviation: TAPC) and the like can also be used.

[0099] The second hole transport layer 112-2 is formed using an organic compound with a relatively high refractive index. Such organic compounds are preferably compounds having a fused aromatic hydrocarbon ring or a fused heteroaromatic ring. The fused aromatic hydrocarbon ring is preferably a fused aromatic hydrocarbon ring containing a naphthalene ring structure, such as a naphthalene ring, an anthracene ring, a phenanthrene ring, or a triphenylene ring. The fused heteroaromatic ring is preferably a carbazole ring, a dibenzofuran ring, or a dibenzothiophene ring structure. For example, benzo[b]naphtho[1,2-d]furan is preferable because it contains a dibenzofuran ring structure.

[0100] In addition, organic compounds containing one or more elements from the third period or later, organic compounds having a terphenyl skeleton, or organic compounds containing both can be suitably used. For example, a biphenyl group substituted with a naphthyl group and a phenyl group substituted with a dibenzofuranyl group can be said to contain a terphenyl skeleton. Specifically, N,N-bis[4-(6-phenylbenzo[b]naphtho[1,2-d]furan-8-yl)phenyl]-4-amino-p-terphenyl (abbreviation: BnfBB1TP), 4,4'-bis[4-(2-naphthyl)phenyl]-4"-phenyltriphenylamine (abbreviation: βNBiB1BP), , N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP), 4-[4′-(carbazol-9-yl)biphenyl-4-yl]-4′-(2-naphthyl)-4″-phenyltriphenylamine (abbreviation: YGTBiβNB), 5,5′-diphenyl-2,2′-di-5H-[1]benzothieno[3,2-c]carbazole (abbreviation: BisBTc), and the like can be suitably used.

[0101] Note that the first electrode 101 preferably includes a reflective electrode that reflects visible light by 40% or more, preferably 70% or more. The second electrode 102 is preferably a semi-transmissive / semi-reflective electrode having a visible light reflectance of 20% to 80%, preferably 40% to 70%. With such a structure, the light-emitting device of one embodiment of the present invention becomes a top-emission light-emitting device that emits light from the second electrode 102 side, and can have a microcavity structure by adjusting the film thickness of the EL layer 103.

[0102] In this case, the optical distance between the interface of the reflective electrode on the EL layer 103 side and the interface of the first hole transport layer 112-1 on the reflective electrode side is preferably λ / 8 to 3λ / 8 for light of wavelength λ. Furthermore, the optical distance between the main light-emitting region of the light-emitting layer 113 and the interface of the first hole transport layer 112-1 on the reflective electrode side is preferably 3λ / 8 to 5λ / 8 for light of wavelength λ. Furthermore, the optical distance between the interface of the reflective electrode on the EL layer 103 side and the interface of the third hole transport layer 112-3 on the reflective electrode side is preferably 3λ / 8 to 5λ / 8 for light of wavelength λ. Furthermore, the optical distance between the main light-emitting region of the light-emitting layer 113 and the interface of the third hole transport layer 112-3 on the light-emitting layer side is preferably λ / 8 to 3λ / 8 for light of wavelength λ. With this configuration, light reflected by the interfaces of each layer and the reflective electrode is amplified, enabling a light-emitting device with high efficiency and good color purity. If it is difficult to accurately determine the main light-emitting region of the light-emitting layer 113, the position may be set as a reference, estimated in consideration of the transport properties of the light-emitting layer 113.

[0103] In one embodiment of the present invention, the light extraction efficiency is improved by stacking multiple hole transport layers with different refractive indices. However, at the same time, the light-emitting device has more layers than a typical light-emitting device. This increases the number of interfaces between the layers, making it more likely to generate resistance due to the interfaces, and may result in an increase in driving voltage.

[0104] Typically, in the hole transport region of an organic semiconductor device, holes must be sequentially injected into layers made of organic compounds with different HOMO levels between the active layer or light-emitting layer and the electrode, considering the exchange of holes with the electrode. Naturally, if the difference in HOMO levels between layers is too large, the driving voltage will increase. Therefore, the difference in HOMO levels is mitigated by placing a layer made of an organic compound with a similar HOMO level difference between the electrode and the active layer (light-emitting layer). However, even when the difference in HOMO levels between layers is not that large, the driving voltage can sometimes increase significantly depending on the combination of organic compounds used. Until now, there have been no guidelines for avoiding this problem, and it has been dismissed as a matter of compatibility between materials.

[0105] Organic compounds include polar and nonpolar molecules. Polar molecules have a permanent dipole moment, but when polar molecules are vapor-deposited, if the vapor-deposited film is randomly oriented, the polarity bias is canceled out and no polarization due to the polarity of the molecules occurs within the film. However, if the vapor-deposited film has molecular orientation, a giant surface potential due to the polarization bias may appear.

[0106] Giant surface potential is a phenomenon in which the surface potential of a vapor-deposited film increases in proportion to the film thickness, and can be explained as a spontaneous orientation polarization phenomenon caused by a slight deviation of the permanent dipole moment of an organic compound in the film thickness direction. To treat its magnitude as a numerical value independent of film thickness, the value obtained by dividing the surface potential of the vapor-deposited film by the film thickness, i.e., the potential gradient (slope) of the surface potential of the vapor-deposited film, can be used. In this specification, the potential gradient of the surface potential of the vapor-deposited film is referred to as GSP (mV / nm).

[0107] By taking this GSP value into consideration, the mismatch that has been considered to be the compatibility of conventional materials as described above can be resolved, and an organic semiconductor device with good characteristics can be easily obtained.

[0108] In one embodiment of the present invention, the GSP of the first hole transport layer 112-1 minus the GSP of the third hole transport layer 112-3 (ΔGSP １−３ ) is preferably 10 (mV / nm) or less, and more preferably 0 (mV / nm) or less. In addition, the value obtained by subtracting the GSP of the third hole transport layer 112-3 from the GSP of the second hole transport layer 112-2 (ΔGSP ２−３ ) is preferably 10 (mV / nm) or less, and more preferably 0 (mV / nm) or less. １−２ and ΔGSP ２−３ It is more preferable that both of these values ​​are 10 (mV / nm) or less, and even more preferable that both of these values ​​are 0 (mV / nm) or less.

[0109] The value obtained by subtracting the GSP of the second hole transport layer 112-2 from the GSP of the first hole transport layer 112-1 (ΔGSP １−２) is preferably 10 (mV / nm) or less, and more preferably 0 (mV / nm) or less.

[0110] This configuration makes it possible to easily obtain a light-emitting device having favorable characteristics such as a low driving voltage, low power consumption, or high power efficiency.

[0111] Furthermore, the GSP of the third hole transport layer 112-3 is preferably higher than that of the first hole transport layer 112-1, and is also preferably higher than that of the second hole transport layer 112-2. It is more preferable that the GSP of the third hole transport layer 112-3 is higher than that of both the first hole transport layer 112-1 and the second hole transport layer 112-2. This configuration makes it possible to obtain a light-emitting device with favorable characteristics, such as a lower driving voltage, lower power consumption, or high power efficiency.

[0112] Furthermore, it is preferable that the GSP of the second hole transport layer 112-2 is higher than the GSP of the first hole transport layer 112-1. With this configuration, it becomes easier to obtain a light-emitting device having favorable characteristics such as a low driving voltage, low power consumption, or high power efficiency.

[0113] The GSP of each layer can be determined by measuring the GSP of a vapor-deposited film of the material (organic compound) that constitutes each layer.

[0114] A method for determining the GSP of an organic compound will now be described.

[0115] Generally, the slope of the surface potential of a deposited film measured by a Kelvin probe plotted against the film thickness direction is discussed as the magnitude of the giant surface potential, i.e., GSP (mV / nm). However, when two different layers are stacked, the polarization charge density (mC / m ２ ) varies in relation to GSP, which can be used to estimate GSP.

[0116] Non-Patent Document 1 shows that when organic thin films (thin film 1 and thin film 2, where thin film 1 is located on the anode side and thin film 2 is located on the cathode side) having different spontaneous polarizations are stacked and a current is passed through them, the following equation holds true:

[0117]

[0118]

[0119] In formula (1), σ ｉｆ is the polarization charge density, V ｉ is the hole injection voltage, V ｂｉ is the threshold voltage, d ２ is the thickness of thin film 2, ε ２ is the dielectric constant of the thin film 2. V ｉ , V ｂｉ can be estimated from the capacitance-voltage characteristics of the device. ｏ In this way, the V estimated from the capacitance-voltage characteristics can be calculated as ｉ , V ｂｉ and the dielectric constant ε of the thin film 2 calculated from the refractive index ２ , and the thickness d of the thin film 2 ２ Therefore, using equation (1), the polarization charge density σ ｉｆ can be obtained.

[0120] Next, in equation (2), σ ｉｆ is the polarization charge density, P ｎ is the GSP of the thin film n, ε ｎ is the dielectric constant of the thin film n. Here, from the above formula (1), the polarization charge density σ ｉｆ Therefore, by using a material with a known GSP as thin film 2, the GSP of thin film 1 can be estimated.

[0121] As described above, the GSP can be determined by the above method using a vapor-deposited film of an organic compound for which the GSP is to be determined as thin film 1.

[0122] In this specification, the thin film 2 is made of Alq, which is known to have a GSP of 48 (mV / nm). ３ The GSP of each thin film was calculated using the formula:

[0123] In addition, it is known that the orientation of a deposited film depends on the substrate temperature during deposition, and the GSP value may also depend on the substrate temperature during deposition. The measurements in this specification are those of films deposited at room temperature during deposition.

[0124] Next, examples of other structures or materials of the light-emitting device of one embodiment of the present invention will be described. As described above, the light-emitting device of one embodiment of the present invention includes the EL layer 103 having a plurality of layers between a pair of electrodes, the first electrode 101 and the second electrode 102. The EL layer 103 includes at least the light-emitting layer 113 containing a light-emitting material and the hole-transport layer 112 (the first hole-transport layer 112-1, the second hole-transport layer 112-2, and the third hole-transport layer 112-3).

[0125] The first electrode 101 is preferably formed using a metal, alloy, conductive compound, or mixture thereof having a large work function (specifically, 4.0 eV or more). Specific examples include indium oxide-tin oxide (ITO), indium oxide-tin oxide containing silicon or silicon oxide, indium oxide-zinc oxide, and indium oxide containing tungsten oxide and zinc oxide (IWZO). These conductive metal oxide films are usually formed by sputtering, but may also be formed by applying a sol-gel method or the like. For example, indium oxide-zinc oxide can be formed by sputtering using a target in which 1 to 20 wt % of zinc oxide is added to indium oxide. Indium oxide containing tungsten oxide and zinc oxide (IWZO) can also be formed by sputtering using a target containing 0.5 to 5 wt % tungsten oxide and 0.1 to 1 wt % zinc oxide relative to indium oxide. Other materials that can be used for the first electrode 101 include, for example, gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), and nitrides of metal materials (e.g., titanium nitride). Alternatively, graphene can be used for the first electrode 101. Note that by using a composite material described below for a layer in contact with the first electrode 101 in the EL layer 103 (typically, the hole-injection layer 111), the electrode material can be selected regardless of the work function.

[0126] When the first electrode 101 is formed of a material that is transparent to the light emitted by the light-emitting device, a light-emitting device that emits light from the first electrode 101 side can be obtained as shown in Fig. 1C. When the first electrode includes an electrode that is reflective to the light emitted by the light-emitting device and the second electrode 102 is formed of a material that is transparent to the light emitted by the light-emitting device, a light-emitting device that emits light from the second electrode side can be obtained as shown in Fig. 1D. Since the hole transport layer 112 is provided between the light-emitting layer 113 and the first electrode, it is preferable that the first electrode include an electrode that is reflective to the light emitted by the light-emitting device.

[0127] The EL layer 103 preferably has a stacked layer structure. However, the stacked layer structure is not particularly limited except for the light-emitting layer 113 and the hole-transport layer 112. Various functional layers can be used, such as a hole-injection layer, an electron-transport layer, an electron-injection layer, a carrier-blocking layer (hole-blocking layer, electron-blocking layer), an exciton-blocking layer, an intermediate layer, and a charge-generation layer. Note that any of the layers may not be provided. In this embodiment, two types of structures will be described: a structure having a hole-injection layer 111, an electron-transport layer 114, and an electron-injection layer 115 in addition to the light-emitting layer 113 and the hole-transport layer, as shown in FIG. 1A; and a structure having a charge-generation layer 116 instead of the electron-injection layer 115, as shown in FIG. 1B.

[0128] The hole injection layer is provided in contact with the anode and has a function of facilitating injection of holes into the EL layer 103. The hole injection layer is made of phthalocyanine (abbreviation: H ２ Pc), copper phthalocyanine complex compounds such as copper phthalocyanine (abbreviation: CuPc), aromatic amine compounds such as 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB) and 4,4'-bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviation: DNTPD), or polymers such as poly(3,4-ethylenedioxythiophene) / polystyrene sulfonic acid (abbreviation: PEDOT / PSS).

[0129] The hole injection layer may be formed using a substance having acceptor properties. Examples of the substance having acceptor properties include organic compounds having an electron-withdrawing group (such as a halogen group or a cyano group), such as 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT-CN), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviation: F6-TCCNNQ), and 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyren-2-ylidene)malononitrile. In particular, compounds in which an electron-withdrawing group is bonded to a fused aromatic ring having a plurality of heteroatoms, such as HAT-CN, are thermally stable and preferred. Also, [3]radialene derivatives having an electron-withdrawing group (especially a halogen group such as a fluoro group, a cyano group, etc.) are preferred because they have very high electron-accepting properties, and specific examples thereof include α,α',α''-1,2,3-cyclopropanetriylidenetris[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α',α''-1,2,3-cyclopropanetriylidenetris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], and α,α',α''-1,2,3-cyclopropanetriylidenetris[2,3,4,5,6-pentafluorobenzeneacetonitrile]. In addition to the organic compounds described above, other substances having acceptor properties can be used, such as molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, manganese oxide, etc. The substance having acceptor properties can extract electrons from the adjacent hole transport layer (or hole transport material) by applying a voltage between the electrodes.

[0130] The hole injection layer may be formed of a composite material containing the above-mentioned material having acceptor properties and a material having hole transport properties. As the material having hole transport properties used for the composite material, various organic compounds such as aromatic amine compounds, heteroaromatic compounds, aromatic hydrocarbons, and polymer compounds (oligomers, dendrimers, polymers, etc.) can be used. The material having hole transport properties used for the composite material can be a 1×10 −６ cm ２ / Vs or more. The material having hole transport properties used in the composite material is preferably a compound having a fused aromatic hydrocarbon ring or a π-electron-rich heteroaromatic ring. As the fused aromatic hydrocarbon ring, an anthracene ring, a naphthalene ring, or the like is preferable. Furthermore, as the π-electron-rich heteroaromatic ring, a fused aromatic ring containing at least one of a pyrrole skeleton, a furan skeleton, and a thiophene skeleton in the ring is preferable, and specifically, a carbazole ring, a dibenzothiophene ring, or a ring in which an aromatic ring or a heteroaromatic ring is further fused to the above ring is preferable.

[0131] The material having such hole-transporting properties preferably has a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, or an anthracene skeleton. In particular, the 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 of the amine via an arylene group. It is preferable that the material having hole-transporting properties is a substance having an N,N-bis(4-biphenyl)amino group, since this allows the fabrication of a light-emitting device with a long lifetime. Specific examples of the material having hole transport properties as described above 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) and 4,4′-bis(6-phenylbenzo[b]naphtho[1,2-d]furan). N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-6-amine (abbreviation: BBABnf(6)), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf(8)), N,N-bis(4-biphenyl)benzo[b]naphtho[2,3- d]furan-4-amine (abbreviation: BBABnf(II)(4)), N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP), N-[4-(dibenzothiophen-4-yl)phenyl]-N-phenyl-4-biphenylamine (abbreviation: ThBA1BP), 4-(2-naphthyl)-4',4''-diphenyltriphenylamine (abbreviation: abbreviation: BBAβNB), 4-[4-(2-naphthyl)phenyl]-4',4''-diphenyltriphenylamine (abbreviation: BBAβNBi), 4,4'-diphenyl-4''-(6;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβNB), 4,4'-diphenyl-4''-(7;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβNB-03), 4,4'-Diphenyl-4''-(7-phenyl)naphthyl-2-yltriphenylamine (abbreviation: BBAPβNB-03), 4,4'-diphenyl-4''-(6;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B), 4,4'-diphenyl-4''-(7;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B-03), 4,4'-diphenyl-4''-(4;2'-binaphthyl-1-yl)triphenylamine (abbreviation: BBAβNαNB), 4,4'-diphenyl-4''-(5;2'- binaphthyl-1-yl)triphenylamine (abbreviation: BBAβNαNB-02), 4-(4-biphenylyl)-4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: TPBiAβNB), 4-(3-biphenylyl)-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (abbreviation: mTPBiAβNBi), 4-(4-biphenylyl)-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (abbreviation: TPBiAβNBi), 4-phenyl-4'-(1-naphthyl)triphenylamine nylamine (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''-phenyl triphenylamine (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,N-(4-biphenyl)-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)trimethylamine 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-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 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]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF), N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF), N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-4-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-3-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-2-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-2-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-1-amine, etc.

[0132] Other aromatic amine compounds that can be used as the material having hole-transport properties include N,N'-di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 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[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B). The organic compounds used for the first hole-transport layer 112-1 and the third hole-transport layer 112-3 can also be used.

[0133] Note that the material having hole-transporting properties used in the composite material is more preferably a substance having a relatively deep HOMO level of -5.7 eV or more and -5.4 eV or less. When the material having hole-transporting properties used in the composite material has a relatively deep HOMO level, injection of holes into the hole-transport layer 112 becomes easy, and a light-emitting device with a long lifetime can be easily obtained. Furthermore, when the material having hole-transporting properties used in the composite material is a substance having a relatively deep HOMO level, induction of holes can be appropriately suppressed, and a light-emitting device with a long lifetime can be obtained.

[0134] The refractive index of the layer can be reduced by further mixing an alkali metal or alkaline earth metal fluoride with the composite material (preferably with a fluorine atom ratio of 20% or more in the layer), which also allows a layer with a low refractive index to be formed inside the EL layer 103, thereby improving the external quantum efficiency of the light-emitting device.

[0135] By forming the hole injection layer 111, the hole injection property becomes good, and a light emitting device with a low driving voltage can be obtained.

[0136] Among substances having acceptor properties, organic compounds having acceptor properties are easy to use because they can be easily vapor-deposited and formed into a film.

[0137] The hole transport layer 112 is formed by containing a material having a hole transport property. −６ cm ２ / Vs or more. The hole-transport layer 112 of the light-emitting device of one embodiment of the present invention has the above-described structure, whereby the light-emitting device can have favorable characteristics. For example, the light-emitting device can have favorable external quantum efficiency, current efficiency, and / or blue index. Note that if the above-described structure is not applied, the hole-transport layer 112 can be formed of a single layer or multiple layers, and the material having hole-transport properties used can be any of the materials listed above as the materials having hole-transport properties that can be used in the composite material of the hole-injection layer.

[0138] An electron blocking layer may be provided between the hole-transporting layer 112 and the light-emitting layer 113. The electron blocking layer is preferably made of a substance that has a hole-transporting property and a LUMO level higher than that of the light-emitting layer 113 by 0.25 eV or more.

[0139] The light-emitting layer 113 preferably contains a light-emitting substance and a host material. The light-emitting layer 113 may also contain other materials. Alternatively, the light-emitting layer 113 may be a laminate of two layers with different compositions.

[0140] The light-emitting substance may be a fluorescent substance, a phosphorescent substance, a substance that exhibits thermally activated delayed fluorescence (TADF), or other light-emitting substances. Note that one embodiment of the present invention is more preferably applicable to the case where the light-emitting layer 113 is a layer that exhibits fluorescent light, particularly a layer that exhibits blue fluorescent light.

[0141] Examples of materials that can be used as the fluorescent substance in the light-emitting layer 113 include the following: In addition, fluorescent substances other than these can also be used.

[0142] 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine (abbreviation: PAP2BPy), 5,6-bis[4'-(10-phenyl-9-anthryl)biphenyl-4-yl]-2,2'-bipyridine (abbreviation: PAPP2BPy), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine )phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn), N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-diphenyl-N-[4-( 10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetra-tert-butylperylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), N,N''-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene)bis[N,N',N'-triphenyl-1,4-phenylenediamine] (abbreviation: DPABPA), N,9 -diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: 2PAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), N,N,N',N',N'',N'',N''',N'''-octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), Coumarin 30, N-(9,10-diphenyl-2-anthryl)-N,9-Diphenyl-9H-carbazole-3-amine (abbreviation: 2PCAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazole-3-amine (abbreviation: 2PCABPhA), N-(9,10-diphenyl-2-anthryl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPA BPhA), 9,10-bis(1,1'-biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracen-2-amine (abbreviation: 2YGABPhA), N,N,9-triphenylanthracen-9-amine (abbreviation: DPhAPhA), Coumarin 545T, N,N'-diphenylquinacridone (abbreviation: DPQd), rubrene, 5,12-bis(1,1'-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6 -methyl-4H-pyran-4-ylidene)propanedinitrile (abbreviation: DCM1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM2), N,N,N',N'-tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine amine (abbreviation: p-mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB), 2-(2,6-bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDCM), 2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJ™), N,N'-diphenyl-N,N'-(1,6-pyren-diyl)bis[(6-phenylbenzo[b ]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-03), 3,10-bis[N-(9-phenyl-9H-carbazol-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10PCA2Nbf(IV)-02), and 3,10-bis[N-(dibenzofuran-3-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10FrA2Nbf(IV)-02). In particular, condensed aromatic diamine compounds typified by pyrene diamine compounds such as 1,6FLPAPrn, 1,6mMemFLPAPrn, and 1,6BnfAPrn-03 are preferred because they have high hole-trapping properties and excellent luminous efficiency or reliability. ,

[0143] When a phosphorescent material is used as the light-emitting material in the light-emitting layer 113, examples of materials that can be used include the following.

[0144] Tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN]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)-5-isopropyl-3-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(iPrptz-3b) ３organometallic iridium complexes having a 4H-triazole skeleton, such as tris[3-methyl-1-(2-methylphenyl)-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 iridium complexes having a 1H-triazole skeleton, such as fac-tris[(1-2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviation: [Ir(iPrpmi) ３ ]), tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: [Ir(dmpimpt-Me) ３ organometallic iridium complexes having an imidazole skeleton, such as 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(CF ３ ppy) ２ (pic)]), bis[2-(4',6'-difluorophenyl)pyridinato-N,C ２’ ] Organometallic iridium complexes having a phenylpyridine derivative having an electron-withdrawing group as a ligand, such as iridium(III) acetylacetonate (abbreviation: FIracac), are examples of such compounds that exhibit blue phosphorescence and have an emission peak in the wavelength range of 440 nm to 520 nm.

[0145] Also, tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm) ３]), tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm) ３ ]), (acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm) ２ (acac)]), (acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm) ２ (acac)]), (acetylacetonato)bis[6-(2-norbornyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(nbppm) ２ (acac)]), (acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(mpmppm) ２ (acac)]), (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm) ２ organometallic iridium complexes having a pyrimidine skeleton, such as (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-Me) ２ (acac)]), (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-iPr) ２ organometallic iridium complexes having a pyrazine skeleton, such as tris(2-phenylpyridinato-N,C(acac)]); 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’ ) iridium(III) acetylacetonate (abbreviation: [Ir(pq) ２ (acac)]), [2-d3-methyl-8-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: Ir(5mppy-d3) ２ (mbfpypy-d3)), [2-(methyl-d3)-8-[4-(1-methylethyl-1-d)-2-pyridinyl-κN]benzofuro2,[3-b]pyridin-7-yl-κC]bis[5-(methyl-d3)-2-[5-(methyl-d3)-2-pyridinyl-κN]phenyl-κC]iridium(III) (abbreviation: Ir(5mtpy-d6) ２ (mbfpypy-iPr-d4)), [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)), [2-(4-methyl-5-phenyl-2-pyridinyl-κN)phenyl-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: Ir(ppy) ２ In addition to organometallic iridium complexes having a pyridine skeleton, such as tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviation: [Tb(acac) ３ These compounds mainly exhibit green phosphorescence, with an emission peak in the wavelength range of 500 nm to 600 nm. Organometallic iridium complexes having a pyrimidine skeleton are particularly preferred because they are remarkably excellent in reliability and luminous efficiency.

[0146] Also, (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(dpm) ２ organometallic iridium complexes having a pyrimidine skeleton, such as (acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: [Ir(tppr) ２ (acac)]), bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: [Ir(tppr) ２ (dpm)]), (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: [Ir(Fdpq) ２ organometallic iridium complexes having a pyrazine skeleton, such as tris(1-phenylisoquinolinato-N,C(acac)]); ２’ ) Iridium(III) (abbreviation: [Ir(piq) ３ ]), bis(1-phenylisoquinolinato-N,C ２’ ) iridium(III) acetylacetonate (abbreviation: [Ir(piq) ２ In addition to organometallic iridium complexes having a pyridine skeleton such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrinplatinum(II) (abbreviation: PtOEP), platinum complexes such as tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III) (abbreviation: [Eu(DBM) ３ (Phen)]), tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III) (abbreviation: [Eu(TTA) ３Examples of rare earth metal complexes include iridium complexes such as iridium complexes containing pyrazine skeletons and iridium complexes containing iridium ions. These compounds exhibit red phosphorescence and have an emission peak in the wavelength range of 600 nm to 700 nm. Organometallic iridium complexes containing pyrazine skeletons exhibit red emission with good chromaticity.

[0147] In addition to the phosphorescent compounds described above, known phosphorescent compounds may be selected and used.

[0148] Examples of TADF materials that can be used include fullerene and its derivatives, acridine and its derivatives, and eosin derivatives. Other examples include metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd). Examples of metal-containing porphyrins include protoporphyrin-tin fluoride complexes (SnF) represented by the following structural formula: ２ (Proto IX)), mesoporphyrin-tin fluoride complex (SnF ２ (Meso IX)), hematoporphyrin-tin fluoride complex (SnF ２ (Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF ２ (Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF ２ (OEP)), etioporphyrin-tin fluoride complex (SnF ２ (Etio I)), octaethylporphyrin-platinum chloride complex (PtCl ２ OEP) and the like.

[0149]

[0150] Further, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 9-(4,6-diphenyl-1,3,5-triazin-2-yl)-9′-phenyl-9H,9′H-3,3′-bicarbazole (abbreviation: PCCzTzn), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 2-[4-(10H-phenoxazin-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), and Heterocyclic compounds having one or both of a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring, such as 3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), and 10-phenyl-10H,10′H-spiro[acridine-9,9′-anthracene]-10′-one (abbreviation: ACRSA), can also be used. The heterocyclic compound has a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring, and therefore has high electron transport and hole transport properties, and is therefore preferred. Among the skeletons having a π-electron-deficient heteroaromatic ring, pyridine skeleton, diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), and triazine skeleton are preferred because they are stable and reliable. In particular, benzofuropyrimidine skeleton, benzothienopyrimidine skeleton, benzofuropyrazine skeleton, and benzothienopyrazine skeleton are preferred because they have high acceptor properties and good reliability. Furthermore, among the skeletons having a π-electron-rich heteroaromatic ring, acridine skeleton, phenoxazine skeleton, phenothiazine skeleton, furan skeleton, thiophene skeleton, and pyrrole skeleton are preferred because they are stable and reliable.The furan skeleton is preferably a dibenzofuran skeleton, and the thiophene skeleton is preferably a dibenzothiophene skeleton. The pyrrole skeleton is particularly preferably an indole skeleton, a carbazole skeleton, an indolocarbazole skeleton, a bicarbazole skeleton, or a 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole skeleton. A substance in which a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded is particularly preferred because the electron-donating property of the π-electron-rich heteroaromatic ring and the electron-accepting property of the π-electron-deficient heteroaromatic ring are both enhanced, reducing the energy difference between the S1 level and the T1 level, thereby enabling efficient thermally activated delayed fluorescence. Instead of the π-electron-deficient heteroaromatic ring, an aromatic ring bonded to an electron-withdrawing group such as a cyano group may be used. The π-electron-rich skeleton may be, for example, an aromatic amine skeleton or a phenazine skeleton. Examples of the π-electron-deficient skeleton that can be used include a xanthene skeleton, a thioxanthene dioxide skeleton, an oxadiazole skeleton, a triazole skeleton, an imidazole skeleton, an anthraquinone skeleton, a boron-containing skeleton such as phenylborane or boranthrene, an aromatic ring having a nitrile group or a cyano group such as benzonitrile or cyanobenzene, a heteroaromatic ring, a carbonyl skeleton such as benzophenone, a phosphine oxide skeleton, a sulfone skeleton, etc. In this way, a π-electron-deficient skeleton and a π-electron-rich skeleton can be used in place of at least one of a π-electron-deficient heteroaromatic ring and a π-electron-rich heteroaromatic ring.

[0151]

[0152] Alternatively, a TADF material in which the singlet excited state and the triplet excited state are in thermal equilibrium may be used. Such a TADF material has a short emission lifetime (excitation lifetime), which can suppress a decrease in efficiency in the high brightness region of a light-emitting element. Specific examples include materials with the molecular structure shown below.

[0153]

[0154] The TADF material is a material that has a small difference between the S1 level and the T1 level and has the function of converting triplet excitation energy to singlet excitation energy by reverse intersystem crossing. Therefore, triplet excitation energy can be upconverted to singlet excitation energy (reverse intersystem crossing) with a small amount of thermal energy, and a singlet excited state can be efficiently generated. Furthermore, triplet excitation energy can be converted into luminescence.

[0155] Furthermore, an exciplex (also called an exciplex) that forms an excited state with two types of substances has an extremely small difference between the S1 level and the T1 level, and functions as a TADF material that can convert triplet excitation energy into singlet excitation energy.

[0156] The T1 level can be determined by using a phosphorescence spectrum observed at low temperatures (e.g., 77 K to 10 K). When a tangent line is drawn at the base of the fluorescence spectrum on the short wavelength side of the TADF material, and the energy of the wavelength of the extrapolated line is defined as the S1 level, and when a tangent line is drawn at the base of the phosphorescence spectrum on the short wavelength side of the TADF material, and the energy of the wavelength of the extrapolated line is defined as the T1 level, the difference between S1 and T1 is preferably 0.3 eV or less, and more preferably 0.2 eV or less.

[0157] When a TADF material is used as a light-emitting material, the S1 level of the host material is preferably higher than the S1 level of the TADF material, and the T1 level of the host material is preferably higher than the T1 level of the TADF material.

[0158] As the host material of the light-emitting layer, various carrier transporting materials such as a material having an electron transporting property or a material having a hole transporting property, or the above-mentioned TADF material can be used.

[0159] As a material having hole transport properties, an organic compound having an amine skeleton, a π-electron-rich heteroaromatic skeleton, etc. is preferable. For example, 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB), N,N′-bis(3-methylphenyl)-N,N′-diphenyl-[1,1′-biphenyl]-4,4′-diamine (abbreviation: TPD), 4,4′-bis[N-(spiro-9,9′-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 4-phenyl-4′-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP ... mBPAFLP), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4 aromatic amine skeletons such as 4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), and N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF). compounds having a carbazole skeleton such as 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), and 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP); 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II);Examples of suitable compounds include compounds having a thiophene skeleton, such as 8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III) and 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and compounds having a furan skeleton, such as 4,4′,4″-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II). Among the compounds listed above, compounds having an aromatic amine skeleton or a carbazole skeleton are preferred because they have good reliability, high hole transport properties, and contribute to reducing driving voltage. In addition, the organic compounds listed as examples of the material having hole transport properties for the hole transport layer 112 can also be used.

[0160] Examples of materials having electron transport properties include bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq ２), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (abbreviation: BAlq), bis(8-quinolinolato)zinc(II) (abbreviation: Znq), bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO), bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ), or other metal complexes; and organic compounds having a π-electron-deficient heteroaromatic ring are preferred. Examples of organic compounds having a π-electron-deficient heteroaromatic ring include 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazole-2- yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 2,2′,2″-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDB organic compounds having an azole skeleton such as 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOs), 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy), 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), bathophenanthroline (abbreviation: Bphen), and bathocuproine (abbreviation: BCP), 2,9-di(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBphen), and other organic compounds containing heteroaromatic rings with a pyridine skeleton, such as 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3′-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), and 2-[3′-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II).h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4'-(9-phenyl-9H-carbazol-3-yl)-3,1'-biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mpPCBPDBq), 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzothiophene 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDBTPDBq-II), 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 9-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9mDBtBPNfpr), 9-[(3'-dibenzothiophen-4-yl)biphenyl-4-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9pm DBtBPNfpr), 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: 4,6mCzP2Pm), 9,9'-[pyrimidine-4,6-diylbis(biphenyl-3,3'-diyl)]bis(9H-carbazole) (abbreviation: 4,6mCzBP2Pm), 8-(1,1'-biphenyl-4-yl) 4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8BP-4mDBtPBfpm), 3,8-bis[3-(dibenzothiophen-4-yl)phenyl]benzofuro[2,3-b]pyrazine (abbreviation: 3,8mDBtP2Bfpr), 4,8-bis[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 4,8mDBtP2Bfpm), 8-[3′-(dibenzothiophen-4-yl)(1,1′-biphenyl-3-yl)]naphtho[1′,2':4,5]furo[3,2-d]pyrimidine (abbreviation: 8mDBtBPNfpm), 8-[(2,2'-binaphthalen)-6-yl]-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8(βN2)-4mDBtPBfpm), 2,2'-(pyridine-2,6-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 2,6(P-Bqn)2Py), 2,2'-(pyridine-2,6-diyl)bis{4-[4-(2-naphthyl)phenyl]-6-phenylpyrimidine} (abbreviation: d2 Py), 6-(1,1'-biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm), 2,6-bis(4-naphthalen-1-ylphenyl)-4-[4-(3-pyridyl)phenyl]pyrimidine (abbreviation: 2,4NP-6PyPPm), 4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenyl-6-(1,1'-biphenyl-4-yl)pyrimidine (abbreviation: 6BP-4Cz2PPm), 7-[4-(9-phenyl-9H-carbazol-9-yl)phenyl]- organic compounds having a diazine skeleton such as 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-1,3,5-triazine (abbreviation: mBnfBPT ... [b]naphtho[1,2-d]furan-6-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn-02), 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), 5-[3-(4,6-diphenyl-1,3,5-triazin-2yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviation: mINc(II)PTzn), 2-{3-[3-(dibenzothiophen-4-yl)phenyl]fluoren-2-yl}phenyl phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mDBtBPTzn), 2,4,6-tris(3'-(pyridin-3-yl)biphenyl-3-yl)-1,3,5-triazine (abbreviation: TmPPPyTz), 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn), 11-( 4-[1,1'-biphenyl]-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), 2-[3'-(triphenylen-2-yl)-1,1'-biphenyl-3-yl]-4,6-diphenyl'1,3,5-triazine (abbreviation: mTpBPTzn), 9-[4-(4,6-diphenyl-1, Examples of suitable organic compounds include those containing heteroaromatic rings with a triazine skeleton, such as [3,5-triazin-2-yl]-2-dibenzothiophenyl]-2-phenyl-9H-carbazole (abbreviation: PCDBfTzn) and 2-[1,1'-biphenyl]-3-yl-4-phenyl-6-(8-[1,1':4',1''-terphenyl]-4-yl-1-dibenzofuranyl)-1,3,5-triazine (abbreviation: mBP-TPDBfTzn). Among the above, organic compounds containing heteroaromatic rings with a diazine skeleton, organic compounds containing heteroaromatic rings with a pyridine skeleton, and organic compounds containing heteroaromatic rings with a triazine skeleton are preferred due to their high reliability. In particular, organic compounds containing heteroaromatic rings with a diazine (pyrimidine or pyrazine) skeleton and organic compounds containing heteroaromatic rings with a triazine skeleton have high electron transport properties and contribute to reduced driving voltage.

[0161] The TADF materials that can be used as the host material can be the same as those listed above. When a TADF material is used as a host material, triplet excitation energy generated in the TADF material is converted into singlet excitation energy by reverse intersystem crossing, and the energy is further transferred to a light-emitting substance, thereby improving the luminous efficiency of the light-emitting device. In this case, the TADF material functions as an energy donor, and the light-emitting substance functions as an energy acceptor.

[0162] This is very effective when the luminescent material is a fluorescent luminescent material. Furthermore, in this case, in order to obtain high luminous efficiency, it is preferable that the S1 level of the TADF material is higher than the S1 level of the fluorescent luminescent material. Furthermore, it is preferable that the T1 level of the TADF material is higher than the S1 level of the fluorescent luminescent material. Therefore, it is preferable that the T1 level of the TADF material is higher than the T1 level of the fluorescent luminescent material.

[0163] It is also preferable to use a TADF material that emits light that overlaps with the wavelength of the lowest-energy absorption band of the fluorescent material, since this allows for smooth transfer of excitation energy from the TADF material to the fluorescent material, resulting in efficient light emission.

[0164] Furthermore, in order to efficiently generate singlet excitation energy from triplet excitation energy through reverse intersystem crossing, it is preferable that carrier recombination occurs in the TADF material. It is also preferable that the triplet excitation energy generated in the TADF material does not transfer to the triplet excitation energy of the fluorescent material. To this end, it is preferable that the fluorescent material has a protecting group around the luminophore (the skeleton responsible for light emission) possessed by the fluorescent material. The protecting group is preferably a substituent without a π bond, and is preferably a saturated hydrocarbon. Specific examples include alkyl groups having 3 to 10 carbon atoms, substituted or unsubstituted cycloalkyl groups having 3 to 10 carbon atoms, and trialkylsilyl groups having 3 to 10 carbon atoms. It is even more preferable that the protecting group has multiple protecting groups. Substituents without a π bond have poor carrier transport function, so the distance between the TADF material and the luminophore of the fluorescent material can be increased without significantly affecting carrier transport or carrier recombination. Here, the luminophore refers to the atomic group (skeleton) responsible for light emission in the fluorescent material. The luminophore preferably has a skeleton having a π bond, preferably contains an aromatic ring, and preferably has a fused aromatic ring or a fused heteroaromatic ring. Examples of the fused aromatic ring or the fused heteroaromatic ring include a phenanthrene skeleton, a stilbene skeleton, an acridone skeleton, a phenoxazine skeleton, and a phenothiazine skeleton. In particular, fluorescent substances having a naphthalene skeleton, an anthracene skeleton, a fluorene skeleton, a chrysene skeleton, a triphenylene skeleton, a tetracene skeleton, a pyrene skeleton, a perylene skeleton, a coumarin skeleton, a quinacridone skeleton, or a naphthobisbenzofuran skeleton are preferred because of their high fluorescence quantum yield.

[0165] When a fluorescent light-emitting substance is used as the light-emitting substance, a material having an anthracene skeleton is suitable as the host material. Using a substance having an anthracene skeleton as the host material for a fluorescent light-emitting substance makes it possible to realize an emitting layer with both excellent luminous efficiency and durability. As a substance having an anthracene skeleton to be used as the host material, a substance having a diphenylanthracene skeleton, particularly a 9,10-diphenylanthracene skeleton, is preferred because it is chemically stable. Furthermore, a host material having a carbazole skeleton is preferred because it enhances hole injection and transport properties. However, a host material containing a benzocarbazole skeleton in which a benzene ring is further condensed to carbazole is more preferred because its HOMO is shallower by about 0.1 eV than that of carbazole, making it easier for holes to enter. In particular, a host material containing a dibenzocarbazole skeleton is preferred because its HOMO is shallower by about 0.1 eV than that of carbazole, making it easier for holes to enter, and it also has excellent hole transport properties and high heat resistance. Therefore, a more preferable host material is a substance having both a 9,10-diphenylanthracene skeleton and a carbazole skeleton (or a benzocarbazole skeleton or a dibenzocarbazole skeleton). Note that, in view of the hole injection / transport property, a benzofluorene skeleton or a dibenzofluorene skeleton may be used instead of the carbazole skeleton.Examples of such substances include 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: CzPA), 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA), 6-[3-(9,10-diphenyl-2-anthryl)phenyl]-benzo[b]naphtho[1,2-d]furan (abbreviation: 2mBnfPPA), 9-phenyl-10-{4-(9-phenyl-9H-fluoren-9-yl)biphenyl-4′-yl} Anthracene (abbreviation: FLPPA), 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: αN-βNPAnth), 9-(1-naphthyl)-10-(2-naphthyl)anthracene (abbreviation: α,βADN), 2-(10-phenylanthracen-9-yl)dibenzofuran, 2-(10-phenyl-9-anthracenyl)-benzo[b] Examples include naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA), 9-(2-naphthyl)-10-[3-(2-naphthyl)phenyl]anthracene (abbreviation: βN-mβNPAnth), 1-[4-(10-[,1,1′-biphenyl]-4-yl-9-anthracenyl)phenyl]-2-ethyl-1H-benzimidazole (abbreviation: EtBImPBPhA), etc. In particular, CzPA, cgDBCzPA2mBnfPPA, and PCzPA are preferred choices because they exhibit very good properties.

[0166] The host material may be a mixture of a plurality of substances. When a mixture of host materials is used, it is preferable to mix a material having electron transport properties with a material having hole transport properties. By mixing a material having electron transport properties with a material having hole transport properties, the transport properties of the light-emitting layer 113 can be easily adjusted, and the recombination region can also be easily controlled. The weight ratio of the content of the material having hole transport properties to the material having electron transport properties may be 1:19 to 19:1 (material having hole transport properties:material having electron transport properties).

[0167] A phosphorescent material can be used as part of the mixed material. The phosphorescent material can be used as an energy donor that provides excitation energy to a fluorescent material when the fluorescent material is used as a light-emitting material.

[0168] Furthermore, these mixed materials may form an exciplex. It is preferable to select a combination that forms an exciplex that emits light that overlaps with the wavelength of the lowest-energy absorption band of the light-emitting material, because this allows for smooth energy transfer and efficient light emission. Furthermore, using this structure is also preferable because it reduces the driving voltage.

[0169] At least one of the materials forming the exciplex may be a phosphorescent material, which allows efficient conversion of triplet excitation energy into singlet excitation energy through reverse intersystem crossing.

[0170] As a combination of materials that efficiently form an exciplex, it is preferable that the HOMO level of the material having hole transport properties is equal to or higher than the HOMO level of the material having electron transport properties. Also, it is preferable that the LUMO level of the material having hole transport properties is equal to or higher than the LUMO level of the material having electron transport properties. Note that the LUMO level and HOMO level of the material can be derived from the electrochemical properties (reduction potential and oxidation potential) of the material measured by cyclic voltammetry (CV).

[0171] The formation of exciplexes can be confirmed, for example, by comparing the emission spectra of a material having hole transport properties, a material having electron transport properties, and a mixed film obtained by mixing these materials, and observing the phenomenon in which the emission spectrum of the mixed film is shifted to longer wavelengths than the emission spectra of each material (or has a new peak on the longer wavelength side). Alternatively, the formation of exciplexes can be confirmed by comparing the transient photoluminescence (PL) of a material having hole transport properties, the transient PL of a material having electron transport properties, and a mixed film obtained by mixing these materials, and observing differences in transient response, such as the transient PL lifetime of the mixed film having a longer-lifetime component or a larger proportion of delayed components than the transient PL lifetimes of the individual materials. The above-mentioned transient PL may also be interpreted as transient electroluminescence (EL). In other words, the formation of exciplexes can also be confirmed by comparing the transient EL of a material having hole transport properties, the transient EL of a material having electron transport properties, and a mixed film obtained by mixing these materials, and observing the differences in transient response.

[0172] The electron transport layer 114 is a layer containing a substance having an electron transport property. The material having an electron transport property is a material having an electron mobility of 1×10 or less at a square root of an electric field strength [V / cm] of 600. −６ cm ２ A substance having an electron mobility of 1 / Vs or more is preferred. Note that other substances can be used as long as they have a higher electron transporting property than holes. Note that the organic compound is preferably an organic compound having a π-electron-deficient heteroaromatic ring. The organic compound having a π-electron-deficient heteroaromatic ring is preferably, for example, one or more of an organic compound having a heteroaromatic ring with a polyazole skeleton, an organic compound having a heteroaromatic ring with a pyridine skeleton, an organic compound having a heteroaromatic ring with a diazine skeleton, and an organic compound having a heteroaromatic ring with a triazine skeleton.

[0173] Specific examples of the material having an electron transport property that can be used for the electron transport layer include 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazole-2-yl)]benzene (abbreviation: OXD-8), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-9 ... organic compounds having an azole skeleton such as 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOs), 3,5-bis[3-(9H-carbazol-9-yl)phenyl] Organic compounds containing heteroaromatic rings with a pyridine skeleton, such as pyridine (abbreviation: 35DCzPPy), 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), bathophenanthroline (abbreviation: Bphen), bathocuproine (abbreviation: BCP), 2,9-di(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBphen), 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3′-( dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4'-(9-phenyl-9H-carbazol-3-yl)-3,1'-biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mpPCBPDBq), 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDBTPDBq-II), and 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 9-[3′-(dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1′,2′:4,5]furo[2,3-b]pyrazine (abbreviation: 9mDBtBPNfpr), 9-[(3′- ... [1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9pmDBtBPNfpr), 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: 4,6mCzP2Pm), 9,9'-[pyrimidine-4,6-diylbis(biphenyl-3,3'-diyl)]bis(9H- carbazole) (abbreviation: 4,6mCzBP2Pm), 8-(1,1'-biphenyl-4-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8BP-4mDBtPBfpm), 3,8-bis[3-(dibenzothiophen-4-yl)phenyl]benzofuro[2,3-b]pyrazine (abbreviation: 3,8mDBtP2Bfpr), 4,8-bis[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 4,8mDBtP2Bfpm), 8- [3'-(dibenzothiophen-4-yl)(1,1'-biphenyl-3-yl)]naphtho[1',2':4,5]furo[3,2-d]pyrimidine (abbreviation: 8mDBtBPNfpm), 8-[(2,2'-binaphthalen)-6-yl]-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8(βN2)-4mDBtPBfpm), 2,2'-(pyridine-2,6-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 2,6(P-Bqn)2Py), 2,2'-(pyridine-2,6-diyl)bis{4-[4-(2-naphthyl)phenyl]-6-phenylpyrimidine} (abbreviation: 2,6(NP-PPm)2Py), 6-(1,1'-biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm), 2,6-bis(4-naphthalen-1-ylphenyl)-4-[4-(3-pyridyl)phenyl]pyrimidine (abbreviation: 2,4NP-6PyPPm), 4-[3,5-bis(9H-carbazol-9-yl)phenyl organic compounds having a diazine skeleton such as 2-[(1,1'-biphenyl)-4-yl]-4-phenyl-6-[9,9'-spirobi(9H-fluoren)-2-yl]-1,3,5-triazine (abbreviation: BP-SFTzn), 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 mBnfBPTzn-02), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-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), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn-02), mPCCzPTzn), 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), 5-[3-(4,6-diphenyl-1,3,5-triazin-2yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviation: mINc(II)PTzn), 2-{3-[3-(dibenzothiophen-4-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mDBtBPTzn), 2,4,6-tris(3′-(pyridin-3-yl)biphenyl-3-yl)-1,3,5-triazine (abbreviation: TmPPPyTz), 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn), 11-(4-[1,1′-biphenyl]-4-yl-6-phenyl-1,3,5-triazin-2-yl)-11,12-dihydro-12-phenyl and organic compounds having a triazine skeleton such as 1,1'-indolo[2,3-a]carbazole (abbreviation: BP-Icz(II)Tzn), 2-[3'-(triphenylen-2-yl)-1,1'-biphenyl-3-yl]-4,6-diphenyl'1,3,5-triazine (abbreviation: mTpBPTzn), 9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzothiophenyl]-2-phenyl-9H-carbazole (abbreviation: PCDBfTzn), and 2-[1,1'-biphenyl]-3-yl-4-phenyl-6-(8-[1,1':4',1''-terphenyl]-4-yl-1-dibenzofuranyl)-1,3,5-triazine (abbreviation: mBP-TPDBfTzn). Among the above, organic compounds containing a heteroaromatic ring having a diazine skeleton, organic compounds containing a heteroaromatic ring having a pyridine skeleton, and organic compounds containing a heteroaromatic ring having a triazine skeleton are preferred because of their high reliability. In particular, organic compounds containing a heteroaromatic ring having a diazine (pyrimidine or pyrazine) skeleton and organic compounds containing a heteroaromatic ring having a triazine skeleton have high electron transport properties and contribute to reducing driving voltage.

[0174] Furthermore, by using a material with a low refractive index and electron transporting properties for the electron transport layer 114, it becomes possible to obtain a light-emitting device with even better characteristics.

[0175] As an organic compound having a low refractive index and electron transport properties that can be used for the electron transport layer 114, an organic compound having at least one six-membered heteroaromatic ring containing one to three nitrogen atoms, a plurality of aromatic hydrocarbon rings each having 6 to 14 carbon atoms forming the ring, at least two of the aromatic hydrocarbon rings being benzene rings, and a plurality of hydrocarbon groups bonding via sp3 hybrid orbitals is preferred.

[0176] In addition, in such an organic compound, the ratio of the total number of carbon atoms forming bonds with sp3 hybrid orbitals to the total number of carbon atoms in the molecule of the organic compound is preferably 10% or more and 60% or less, and more preferably 10% or more and 50% or less. １ In the results of measuring the organic compound by H-NMR, the integral value of signals below 4 ppm is preferably at least half the integral value of signals at 4 ppm or higher.

[0177] The organic compound having electron transport properties preferably has a molecular weight of 500 to 2000. It is also preferable that all of the hydrocarbon groups forming bonds with sp3 hybrid orbitals of the organic compound are bonded to the aromatic hydrocarbon ring having 6 to 14 carbon atoms that forms the ring, and that the LUMO of the organic compound is not distributed in the aromatic hydrocarbon ring.

[0178] The organic compound having the electron transport property is a compound represented by the following general formula (G ｅ１ 1) or (G ｅ１ The organic compounds represented by 2) are preferred.

[0179]

[0180] In the formula, A represents a 6-membered heteroaromatic ring containing 1 to 3 nitrogen atoms, and is preferably a pyridine ring, a pyrimidine ring, a pyrazine ring, a pyridazine ring, or a triazine ring.

[0181] Also, R ２００ represents any one of hydrogen, an alkyl group having 1 to 6 carbon atoms, an alicyclic group having 3 to 10 carbon atoms, and a substituent represented by formula (G1-1).

[0182] R ２０１ ~R２１５ At least one of R is a phenyl group having a substituent, and the others each independently represent any one of hydrogen, an alkyl group having 1 to 6 carbon atoms, an alicyclic group having 3 to 10 carbon atoms, a substituted or unsubstituted ring-forming aromatic hydrocarbon group having 6 to 14 carbon atoms, and a substituted or unsubstituted pyridyl group. ２０１ , R ２０３ , R ２０５ , R ２０６ , R ２０８ , R ２１０ , R ２１１ , R ２１３ and R ２１５ is preferably hydrogen. The phenyl group having the substituent has one or two substituents, each of which is independently any one of an alkyl group having 1 to 6 carbon atoms, an alicyclic group having 3 to 10 carbon atoms, and a substituted or unsubstituted aromatic hydrocarbon group having 6 to 14 carbon atoms in a ring.

[0183] In addition, the above general formula (G ｅ１ The organic compound represented by 1) has a plurality of hydrocarbon groups selected from alkyl groups having 1 to 6 carbon atoms and alicyclic groups having 3 to 10 carbon atoms, and the ratio of the total number of carbon atoms forming bonds via sp3 hybrid orbitals to the total number of carbon atoms in the molecule is 10% or more and 60% or less.

[0184] In addition, the organic compound having the electron transport property is a compound represented by the following general formula (G ｅ１ The organic compounds represented by 2) are preferred.

[0185]

[0186] In the formula, Q １ ~Q ３ 2 or 3 of the groups represent N, and the Q １ ~Q ３ If two of the groups are N, the remaining group represents CH.

[0187] Also R ２０１ ~R ２１５At least one of R is a phenyl group having a substituent, and the others each independently represent any one of hydrogen, an alkyl group having 1 to 6 carbon atoms, an alicyclic group having 3 to 10 carbon atoms, a substituted or unsubstituted ring-forming aromatic hydrocarbon group having 6 to 14 carbon atoms, and a substituted or unsubstituted pyridyl group. ２０１ , R ２０３ , R ２０５ , R ２０６ , R ２０８ , R ２１０ , R ２１１ , R ２１３ and R ２１５ is preferably hydrogen. The phenyl group having a substituent has one or two substituents, each of which is independently any one of an alkyl group having 1 to 6 carbon atoms, an alicyclic group having 3 to 10 carbon atoms, and a substituted or unsubstituted aromatic hydrocarbon group having 6 to 14 carbon atoms in a ring.

[0188] In addition, the above general formula (G ｅ１ The organic compound represented by 2) preferably has a plurality of hydrocarbon groups selected from alkyl groups having 1 to 6 carbon atoms and alicyclic groups having 3 to 10 carbon atoms, and the ratio of the total number of carbon atoms forming bonds via sp3 hybrid orbitals to the total number of carbon atoms in the molecule is preferably 10% or more and 60% or less.

[0189] In addition, the above general formula (G ｅ１ 1) or (G ｅ１ In the organic compound represented by formula (G 2), the phenyl group having a substituent is ｅ１ 1-2) is preferred.

[0190]

[0191] In the formula, α represents a substituted or unsubstituted phenylene group, and is preferably a meta-substituted phenylene group. Furthermore, when the meta-substituted phenylene group has one substituent, the substituent is preferably also substituted at the meta-position. The substituent is preferably an alkyl group having 1 to 6 carbon atoms or an alicyclic group having 3 to 10 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms, and even more preferably a t-butyl group.

[0192] R２２０ represents an alkyl group having 1 to 6 carbon atoms, an alicyclic group having 3 to 10 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 14 carbon atoms in a ring.

[0193] In addition, j and n represent 1 or 2. When j is 2, the multiple α may be the same or different. When k is 2, the multiple R ２２０ may be the same or different. ２２０ is preferably a phenyl group, and is a phenyl group having an alkyl group having 1 to 6 carbon atoms or an alicyclic group having 3 to 10 carbon atoms at one or both of the two meta positions. The substituents that the phenyl group has at one or both of the two meta positions are more preferably alkyl groups having 1 to 6 carbon atoms, and even more preferably t-butyl groups.

[0194] The organic compound having the electron transport property as described above is an organic compound having an ordinary refractive index of 1.50 or more and 1.75 or less in the blue light emission region (455 nm or more and 465 nm or less), or an ordinary refractive index of 1.45 or more and 1.70 or less for light of 633 nm, which is usually used for measuring refractive index, and having good electron transport property.

[0195] When the above organic compound having electron-transport properties is used for the electron-transport layer 114, the electron-transport layer 114 preferably further contains a metal complex of an alkali metal or an alkaline earth metal. Heterocyclic compounds having a diazine skeleton, heterocyclic compounds having a triazine skeleton, and heterocyclic compounds having a pyridine skeleton are preferred from the viewpoint of operating life because they easily stabilize the energy when they form an exciplex with an organic metal complex of an alkali metal (easily lengthening the emission wavelength of the exciplex). In particular, heterocyclic compounds having a diazine skeleton or heterocyclic compounds having a triazine skeleton are suitable for stabilizing the energy of the exciplex because they have a deep LUMO level.

[0196] The alkali metal organometallic complex is preferably a sodium or lithium metal complex. Alternatively, the alkali metal organometallic complex preferably has a ligand having a quinolinol skeleton. More preferably, the alkali metal organometallic complex is a lithium complex having an 8-quinolinolato structure or a derivative thereof. As a derivative of a lithium complex having an 8-quinolinolato structure, a lithium complex having an 8-quinolinolato structure with an alkyl group is preferred, and a methyl group is particularly preferred.

[0197] 8-quinolinolato-lithium having an alkyl group can be made into a metal complex having a small refractive index. Specifically, in a thin film state, the ordinary refractive index for light having a wavelength in the range of 455 nm to 465 nm can be 1.45 to 1.70, and the ordinary refractive index for light having a wavelength of 633 nm can be 1.40 to 1.65.

[0198] Specific examples of the metal complex include 8-hydroxyquinolinato-lithium (abbreviated as Liq) and 8-hydroxyquinolinato-sodium (abbreviated as Naq). In particular, monovalent metal ion complexes, especially lithium complexes, are preferred, with Liq being more preferred. In addition, when an 8-hydroxyquinolinato structure is included, it is also preferred to use its methyl-substituted derivatives (e.g., 2-methyl-substituted, 5-methyl-substituted, or 6-methyl-substituted derivatives). In particular, the use of an alkali metal complex having an 8-quinolinolato structure with an alkyl group at the 6th position has the effect of reducing the driving voltage of a light-emitting device.

[0199] The electron transport layer 114 has an electron mobility of 1×10 when the square root of the electric field strength [V / cm] is 600. −７ cm ２ / Vs or more 5×10 −５ cm ２ / Vs or less. By reducing the electron transport property of the electron-transport layer 114, the amount of electrons injected into the light-emitting layer can be controlled, and the light-emitting layer can be prevented from becoming an electron-excess state. This structure is particularly preferable when the hole-injection layer is formed of a composite material and the HOMO level of the material having hole-transport properties in the composite material is a substance having a relatively deep HOMO level of -5.7 eV or more and -5.4 eV or less, because this structure provides a long lifetime. In this case, the HOMO level of the material having electron-transport properties is preferably -6.0 eV or more.

[0200] Between the electron transport layer 114 and the second electrode 102, an electron injection layer 115 containing lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF ２ Alternatively, a layer containing an alkali metal or alkaline earth metal, such as 8-hydroxyquinolinato-lithium (abbreviated as Liq), or a compound or complex thereof may be provided. The electron injection layer 115 may be an electride, in which an alkali metal, alkaline earth metal, or a compound thereof is contained in a layer made of a substance having electron transport properties. Examples of the electride include a substance in which electrons are added at a high concentration to a mixed oxide of calcium and aluminum.

[0201] Note that a layer containing a substance having an electron transport property (preferably an organic compound having a bipyridine skeleton) containing a fluoride of the alkali metal or alkaline earth metal at a concentration (50 wt % or more) that results in a microcrystalline state can also be used as the electron-injection layer 115. Since this layer has a low refractive index, it is possible to provide a light-emitting device with better external quantum efficiency.

[0202] Alternatively, a charge generation layer 116 may be provided instead of the electron injection layer 115 of FIG. 1A (FIG. 1B). The charge generation layer 116 is a layer capable of injecting holes into a layer in contact with the cathode side of the charge generation layer 116 and electrons into a layer in contact with the anode side of the charge generation layer 116 by applying a potential thereto. The charge generation layer 116 includes at least a P-type layer 117. The P-type layer 117 is preferably formed using a composite material listed above as a material that can be used to form the hole injection layer 111. The P-type layer 117 may also be formed by laminating a film containing an acceptor material and a film containing a hole transport material, both of which are materials that can be used to form the composite material. By applying a potential to the P-type layer 117, electrons are injected into the electron transport layer 114 and holes are injected into the second electrode 102, which is the cathode, thereby operating the light-emitting device.

[0203] It is preferable that the charge generating layer 116 be provided with either or both of an electron relay layer 118 and an electron injection buffer layer 119 in addition to the P-type layer 117 .

[0204] The electron relay layer 118 contains at least a substance having electron transport properties and has the function of preventing interaction between the electron injection buffer layer 119 and the P-type layer 117 and smoothly transferring electrons. The LUMO level of the substance having electron transport properties contained in the electron relay layer 118 is preferably between the LUMO level of the acceptor substance in the P-type layer 117 and the LUMO level of the substance contained in the layer of the electron transport layer 114 that is in contact with the charge generation layer 116. The specific energy level of the LUMO level of the substance having electron transport properties used in the electron relay layer 118 is −5.0 eV or higher, preferably −5.0 eV or higher and −3.0 eV or lower. Note that the substance having electron transport properties used in the electron relay layer 118 is preferably a phthalocyanine-based material or a metal complex having a metal-oxygen bond and an aromatic ligand.

[0205] The electron injection buffer layer 119 can be made of a material with high electron injection properties, such as an alkali metal, an alkaline earth metal, a rare earth metal, or a compound thereof (an alkali metal compound (including an oxide such as lithium oxide, a halide, or a carbonate such as lithium carbonate or cesium carbonate), an alkaline earth metal compound (including an oxide, a halide, or a carbonate), or a rare earth metal compound (including an oxide, a halide, or a carbonate)).

[0206] Furthermore, in the case where the electron injection buffer layer 119 is formed to contain a substance having an electron transport property and a donor substance, examples of the donor substance that can be used include alkali metals, alkaline earth metals, rare earth metals, and compounds thereof (alkali metal compounds (including oxides such as lithium oxide, halides, and carbonates such as lithium carbonate and cesium carbonate), alkaline earth metal compounds (including oxides, halides, and carbonates), and rare earth metal compounds (including oxides, halides, and carbonates)), as well as organic compounds such as tetrathianaphthacene (abbreviation: TTN), nickelocene, and decamethylnickelocene.

[0207] As the substance having an electron-transporting property, the same material as the material constituting the electron-transporting layer 114 described above can be used. Since the material is an organic compound with a low refractive index, by using the material for the electron-injection buffer layer 119, a light-emitting device with good external quantum efficiency can be obtained.

[0208] The second electrode 102 can be formed from a metal, alloy, electrically conductive compound, or mixture thereof having a low work function (specifically, 3.8 eV or less). Specific examples of such cathode materials include alkali metals such as lithium (Li) or cesium (Cs), elements belonging to Group 1 or Group 2 of the periodic table such as magnesium (Mg), calcium (Ca), and strontium (Sr), alloys containing these (MgAg, AlLi), rare earth metals such as europium (Eu) and ytterbium (Yb), and alloys containing these. However, by providing an electron injection layer between the second electrode 102 and the electron transport layer, various conductive materials, such as Al, Ag, ITO, and indium oxide-tin oxide containing silicon or silicon oxide, can be used as the second electrode 102, regardless of the magnitude of the work function.

[0209] When the second electrode 102 is formed of a material that is transparent to visible light, the light-emitting device can emit light from the cathode side as shown in Fig. 1D. When the first electrode 101 is formed on the substrate side, the light-emitting device can be a so-called top-emission type light-emitting device.

[0210] These conductive materials can be formed into films by dry methods such as vacuum deposition or sputtering, inkjet methods, spin coating methods, etc. Alternatively, they may be formed by wet methods using a sol-gel method, or by wet methods using a paste of a metal material.

[0211] The EL layer 103 may be formed by any of various methods, including dry and wet methods, such as vacuum deposition, gravure printing, offset printing, screen printing, inkjet printing, and spin coating.

[0212] Furthermore, the above-mentioned electrodes or layers may be formed using different film formation methods.

[0213] The configuration of the layer provided between the first electrode 101 and the second electrode 102 is not limited to the above. However, a configuration in which a light-emitting region where holes and electrons recombine is provided at a position away from the first electrode 101 and the second electrode 102 is preferable so as to suppress quenching caused by the proximity of the light-emitting region to the metal used in the electrode or the carrier injection layer.

[0214] Furthermore, the hole transport layer or electron transport layer in contact with the light-emitting layer 113, particularly the carrier transport layer close to the recombination region in the light-emitting layer 113, is preferably composed of a substance having a band gap larger than the band gap of the light-emitting material constituting the light-emitting layer or the light-emitting material contained in the light-emitting layer, in order to suppress energy transfer from excitons generated in the light-emitting layer.

[0215] Next, an embodiment of a light-emitting device (also called a stacked element or tandem element) having a configuration in which multiple light-emitting units are stacked will be described. This light-emitting device has multiple light-emitting units between an anode and a cathode. One light-emitting unit has a configuration substantially similar to that of the EL layer 103 shown in FIG. 1A. In other words, a tandem element is a light-emitting device having multiple light-emitting units, and the light-emitting device shown in FIG. 1A or 1B can be said to be a light-emitting device having one light-emitting unit.

[0216] In a tandem element, a first light-emitting unit and a second light-emitting unit are stacked between an anode and a cathode, and a charge generation layer is provided between the first light-emitting unit and the second light-emitting unit. The anode and cathode correspond to the first electrode 101 and the second electrode 102 in FIG. 1A, respectively, and the same electrodes as those described in the description of FIG. 1A can be applied. The first light-emitting unit and the second light-emitting unit may have the same or different configurations.

[0217] The charge generation layer in a tandem element has the function of injecting electrons into one light-emitting unit and injecting holes into the other light-emitting unit when a voltage is applied to the anode and the cathode. That is, when a voltage is applied so that the potential of the anode is higher than the potential of the cathode, the charge generation layer may inject electrons into the first light-emitting unit and inject holes into the second light-emitting unit.

[0218] The charge generation layer is preferably formed to have the same structure as the charge generation layer 116 described in FIG. 1B. A composite material of an organic compound and a metal oxide has excellent carrier injection and carrier transport properties, and therefore can achieve low-voltage driving and low-current driving. Note that when the anode-side surface of the light-emitting unit is in contact with the charge generation layer, the charge generation layer can also serve as the hole injection layer of the light-emitting unit, and therefore the light-emitting unit does not need to be provided with a hole injection layer.

[0219] Furthermore, when the electron injection buffer layer 119 is provided in the charge generation layer of a tandem element, the electron injection buffer layer 119 plays the role of an electron injection layer in the light-emitting unit on the anode side, and therefore it is not necessarily required to form an electron injection layer in the light-emitting unit on the anode side.

[0220] While the above describes a tandem element having two light-emitting units, the same can be applied to a tandem element having three or more stacked light-emitting units. By arranging multiple light-emitting units between a pair of electrodes and separating them with a charge-generating layer, it is possible to achieve a device that emits high-intensity light while maintaining a low current density and has a long life. It is also possible to realize a light-emitting device that can be driven at a low voltage and consumes little power.

[0221] Furthermore, by making the emission colors of the respective light-emitting units different, it is possible to obtain light emission of a desired color from the light-emitting device as a whole. For example, in a light-emitting device having two light-emitting units, it is possible to obtain a light-emitting device that emits white light from the entire device by obtaining red and green emission colors from the first light-emitting unit and blue emission color from the second light-emitting unit.

[0222] The EL layer 103 or each layer or electrode such as the first light-emitting unit, the second light-emitting unit, and the charge generation layer can be formed by, for example, a vapor deposition method (including a vacuum vapor deposition method), a droplet discharge method (also called an ink-jet method), a coating method, a gravure printing method, etc. They may also contain a low-molecular-weight material, a medium-molecular-weight material (including an oligomer and a dendrimer), or a polymer material.

[0223] This embodiment mode can be freely combined with other embodiment modes.

[0224] Embodiment Mode 2 In this embodiment mode, a light-emitting apparatus using the light-emitting device described in Embodiment Mode 1 will be described.

[0225] In this embodiment, a light-emitting device manufactured using the light-emitting device described in Embodiment 1 will be described with reference to FIGS. 2A and 2B. FIG. 2A is a top view showing the light-emitting device, and FIG. 2B is a cross-sectional view taken along dashed lines A-B and C-D in FIG. 2A. This light-emitting device includes a driver circuit section (source line driver circuit) 601, a pixel section 602, and a driver circuit section (gate line driver circuit) 603, all of which are shown by dotted lines, to control light emission from the light-emitting device. Reference numeral 604 denotes a sealing substrate, 605 denotes a sealant, and the inside surrounded by the sealant 605 forms a space 607.

[0226] The routing wiring 608 is wiring for transmitting signals input to the driving circuits 601 and 603, and receives video signals, clock signals, start signals, reset signals, etc. from an FPC (flexible printed circuit) 609, which serves as an external input terminal. Although only the FPC is shown here, a printed wiring board (PWB) may be attached to this FPC. In this specification, the light-emitting device includes not only the light-emitting device itself, but also a state in which an FPC or PWB is attached to it.

[0227] Next, the cross-sectional structure will be described with reference to Fig. 2B. A driver circuit portion and a pixel portion are formed on an element substrate 610, and here, a driver circuit 601 which is the driver circuit portion and one pixel in a pixel portion 602 are shown.

[0228] The element substrate 610 may be made of a substrate made of glass, quartz, organic resin, metal, alloy, semiconductor, or the like, or a plastic substrate made of FRP (Fiber Reinforced Plastics), PVF (Polyvinyl Fluoride), polyester, acrylic resin, or the like.

[0229] The structure of a transistor used in a pixel or a driver circuit is not particularly limited. For example, an inverted staggered transistor or a staggered transistor may be used. Furthermore, a top-gate transistor or a bottom-gate transistor may be used. The semiconductor material used for the transistor is not particularly limited, and examples thereof include silicon, germanium, silicon carbide, and gallium nitride. Alternatively, an oxide semiconductor containing at least one of indium, gallium, and zinc, such as an In—Ga—Zn-based metal oxide, may be used.

[0230] 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.

[0231] Here, it is preferable to use an oxide semiconductor for the transistors provided in the pixel or the driver circuit, as well as for semiconductor devices such as transistors used in touch sensors, which will be described later. In particular, it is preferable to use an oxide semiconductor having a wider band gap than silicon. By using an oxide semiconductor having a wider band gap than silicon, the current in the off state of the transistor can be reduced.

[0232] The oxide semiconductor preferably contains at least indium (In) or zinc (Zn), and more preferably contains an oxide represented by In-M-Zn-based oxide (M is a metal such as Al, Ti, Ga, Ge, Y, Zr, Sn, La, Ce, or Hf).

[0233] In particular, it is preferable to use, as the semiconductor layer, an oxide semiconductor film which has a plurality of crystal parts whose c-axes are oriented perpendicular to a surface on which the semiconductor layer is formed or a top surface of the semiconductor layer and which does not have grain boundaries between adjacent crystal parts.

[0234] By using such a material for the semiconductor layer, fluctuations in electrical characteristics are suppressed, and a highly reliable transistor can be realized.

[0235] Furthermore, a transistor having the above-described semiconductor layer can retain charge stored in a capacitor through the transistor for a long period of time due to its low off-state current. By applying such a transistor to a pixel, it is possible to stop the driver circuit while maintaining the gray level of an image displayed in each display region. As a result, an electronic device with extremely low power consumption can be realized.

[0236] For example, to stabilize the characteristics of a transistor, it is preferable to provide a base film. The base film can be formed as a single layer or a stacked layer using an inorganic insulating film such as a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a silicon nitride oxide film. The base film can be formed by a sputtering method, a CVD (Chemical Vapor Deposition) method (such as a plasma CVD method, a thermal CVD method, or a MOCVD (Metal Organic CVD) method), an ALD (Atomic Layer Deposition) method, a coating method, a printing method, or the like. Note that the base film need not be provided if it is not necessary.

[0237] The FET 623 indicates one of the transistors formed in the drive circuit section 601. The drive circuit may be formed of various CMOS circuits, PMOS circuits, or NMOS circuits. Although this embodiment shows a driver-integrated type in which the drive circuit is formed on a substrate, this is not necessarily required, and the drive circuit may also be formed externally rather than on the substrate.

[0238] Furthermore, the pixel portion 602 is formed by a plurality of pixels including a switching FET 611, a current control FET 612, and a first electrode 613 electrically connected to the drain of the FET, but is not limited to this, and the pixel portion may be formed by combining three or more FETs and a capacitance element.

[0239] An insulator 614 is formed to cover an end portion of the first electrode 613. Here, the insulator 614 can be formed by using a positive photosensitive acrylic resin film.

[0240] Furthermore, in order to improve the coverage of the EL layer and the like to be formed later, a curved surface having a curvature is formed at the upper or lower end of the insulator 614. For example, when a positive photosensitive acrylic resin is used as the material of the insulator 614, it is preferable to provide a curved surface having a curvature radius (0.2 μm to 3 μm) only at the upper end of the insulator 614. Furthermore, either a negative photosensitive resin or a positive photosensitive resin can be used as the insulator 614.

[0241] An EL layer 616 and a second electrode 617 are formed on the first electrode 613. Here, the first electrode 613 functions as an anode. Materials that can be used for the anode are preferably those with a large work function. For example, a single layer film such as an ITO film, an indium tin oxide film containing silicon, an indium oxide film containing 2 to 20 wt % zinc oxide, a titanium nitride film, a chromium film, a tungsten film, a Zn film, or a Pt film can be used. Other examples include a laminated structure with a silver-based film, a laminated structure with a titanium nitride film and an aluminum-based film, and a three-layer structure with a titanium nitride film, an aluminum-based film, and a titanium nitride film. The laminated structure provides low wiring resistance, good ohmic contact, and the anode can function well.

[0242] The EL layer 616 can be formed by various methods such as evaporation using an evaporation mask, ink-jet printing, spin coating, etc. The EL layer 616 has the structure described in Embodiment Mode 1.

[0243] Furthermore, a material having a small work function (Al, Mg, Li, Ca, or an alloy or compound thereof (MgAg, MgIn, AlLi, etc.)) is preferably used as a material for the second electrode 617 formed on the EL layer 616. Note that when light generated in the EL layer 616 is transmitted through the second electrode 617, it is preferable to use a stack of a thin metal or alloy film and a transparent conductive film (ITO, indium oxide containing 2 to 20 wt % zinc oxide, indium tin oxide containing silicon, zinc oxide (ZnO), etc.) as the second electrode 617.

[0244] Note that a light-emitting device is formed with the first electrode 613, the EL layer 616, and the second electrode 617. The light-emitting device is the light-emitting device described in Embodiment 1. Note that a pixel portion is formed with a plurality of light-emitting devices, but the light-emitting device in this embodiment may include both the light-emitting device described in Embodiment 1 and light-emitting devices having other structures. In this case, in the light-emitting device of one embodiment of the present invention, a common hole-transport layer can be used between light-emitting devices emitting light of different wavelengths, and therefore the light-emitting device can be manufactured with a simple process and is advantageous in terms of cost.

[0245] Furthermore, by bonding the sealing substrate 604 to the element substrate 610 with a sealing material 605, a structure is formed in which a light-emitting device 618 is provided in a space 607 surrounded by the element substrate 610, the sealing substrate 604, and the sealing material 605. The space 607 is filled with a filler, and in some cases, the space is filled with an inert gas (nitrogen, argon, etc.), or with a sealing material. A recess is formed in the sealing substrate, and by providing a desiccant therein, deterioration due to the influence of moisture can be suppressed, which is a preferable configuration.

[0246] It is preferable to use an epoxy resin or glass frit for the sealing material 605. It is also desirable that these materials are as moisture- and oxygen-impermeable as possible. In addition to a glass substrate or a quartz substrate, the sealing substrate 604 can also be made of a plastic substrate made of FRP (Fiber Reinforced Plastics), PVF (Polyvinyl Fluoride), polyester, acrylic resin, or the like.

[0247] Although not shown in Figures 2A and 2B, a protective film may be provided on the cathode. The protective film may be formed of an organic resin film or an inorganic insulating film. The protective film may also be formed so as to cover the exposed portion of the sealing material 605. The protective film may also be provided so as to cover the surfaces and side surfaces of the pair of substrates, the exposed side surfaces of the sealing layer, the insulating layer, etc.

[0248] The protective film can be made of a material that is impermeable to impurities such as water, and therefore can effectively prevent impurities such as water from diffusing from the outside to the inside.

[0249] The protective film may be made of an oxide, nitride, fluoride, sulfide, ternary compound, metal, polymer, or the like. For example, a material containing aluminum oxide, hafnium oxide, hafnium silicate, lanthanum oxide, silicon oxide, strontium titanate, tantalum oxide, titanium oxide, zinc oxide, niobium oxide, zirconium oxide, tin oxide, yttrium oxide, cerium oxide, scandium oxide, erbium oxide, vanadium oxide, indium oxide, or the like; a material containing aluminum nitride, hafnium nitride, silicon nitride, tantalum nitride, titanium nitride, niobium nitride, molybdenum nitride, zirconium nitride, or gallium nitride, or the like; a nitride containing titanium and aluminum, an oxide containing titanium and aluminum, an oxide containing aluminum and zinc, a sulfide containing manganese and zinc, a sulfide containing cerium and strontium, an oxide containing erbium and aluminum, or an oxide containing yttrium and zirconium, or the like.

[0250] The protective film is preferably formed using a film formation method that provides good step coverage. One such method is atomic layer deposition (ALD). It is preferable to use a material that can be formed using the ALD method for the protective film. By using the ALD method, it is possible to form a dense protective film with reduced defects such as cracks or pinholes, or with a uniform thickness. Furthermore, it is possible to reduce damage to the workpiece when forming the protective film.

[0251] For example, by forming a protective film using the ALD method, it is possible to form a uniform protective film with few defects on surfaces having complex uneven shapes, including the top, side, and back surfaces of the touch panel.

[0252] In the above manner, a light-emitting device manufactured using the light-emitting device described in Embodiment Mode 1 can be obtained.

[0253] The light-emitting device in this embodiment can have good characteristics because it uses the light-emitting device described in Embodiment 1. Specifically, the light-emitting device described in Embodiment 1 has good luminous efficiency, so that it can be a light-emitting device with low power consumption.

[0254] 3A and 3B show an example of a light-emitting device in which color purity is improved by providing a colored layer (color filter), etc. Fig. 3A illustrates a substrate 1001, a base insulating film 1002, a gate insulating film 1003, gate electrodes 1006, 1007, and 1008, a first interlayer insulating film 1020, a second interlayer insulating film 1021, a peripheral portion 1042, a pixel portion 1040, a driver circuit portion 1041, anodes 1024R, 1024G, and 1024B of the light-emitting device, a partition wall 1025, an EL layer 1028, a second electrode 1029 of the light-emitting device, a sealing substrate 1031, a sealant 1032, and the like.

[0255] 3A, the colored layers (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B) are provided on a transparent base material 1033. A black matrix 1035 may also be provided. The transparent base material 1033 provided with the colored layers and black matrix is ​​aligned and fixed to the substrate 1001. The colored layers and black matrix 1035 are covered with an overcoat layer 1036.

[0256] 3B shows an example in which colored layers (a red colored layer 1034R, a green colored layer 1034G, and a blue colored layer 1034B) are formed between the gate insulating film 1003 and the first interlayer insulating film 1020. In this manner, the colored layers may be provided between the substrate 1001 and the sealing substrate 1031.

[0257] Furthermore, the light-emitting device described above has a structure (bottom emission type) in which light is extracted from the substrate 1001 side on which the FET is formed, but a structure (top emission type) in which light is extracted from the sealing substrate 1031 side may also be used. A cross-sectional view of a top emission type light-emitting device is shown in FIG. 4. In this case, a light-opaque substrate can be used as the substrate 1001. The process is the same as for a bottom emission type light-emitting device until a connection electrode connecting the FET and the anode of the light-emitting device is formed. Thereafter, a third interlayer insulating film 1037 is formed to cover the electrode 1022. This insulating film may also serve as a planarizing film. The third interlayer insulating film 1037 can be formed using the same material as the second interlayer insulating film, as well as other known materials.

[0258] Although the anodes 1024R, 1024G, and 1024B of the light-emitting device are herein referred to as anodes, they may be cathodes. In the case of a top-emission light-emitting device such as that shown in FIG. 4, the anodes are preferably reflective electrodes. The EL layer 1028 has the same structure as that described for the EL layer 103 in the first embodiment.

[0259] In the top-emission structure shown in FIG. 4 , sealing can be performed using a sealing substrate 1031 provided with colored layers (a red colored layer 1034R, a green colored layer 1034G, and a blue colored layer 1034B). The sealing substrate 1031 may be provided with a black matrix 1035 positioned between pixels. The colored layers (the red colored layer 1034R, the green colored layer 1034G, and the blue colored layer 1034B) or the black matrix may be covered with an overcoat layer 1036. Note that the sealing substrate 1031 is a light-transmitting substrate.

[0260] A microcavity structure is suitable for use in top-emission light-emitting devices. A light-emitting device with a microcavity structure can be obtained by using one electrode including a reflective electrode and the other electrode as a semi-transparent / semi-reflective electrode. At least an EL layer is present between the reflective electrode and the semi-transparent / semi-reflective electrode, and at least a light-emitting layer that serves as a light-emitting region is present.

[0261] The reflectance of the reflective electrode to visible light is 40% to 100%, preferably 70% to 100%, and the resistivity is 1×10 −２ The semi-transmitting and semi-reflective electrode has a visible light reflectance of 20% to 80%, preferably 40% to 70%, and a resistivity of 1×10 −２ It is assumed that the film has a resistivity of Ωcm or less.

[0262] Light emitted from the light-emitting layer included in the EL layer is reflected by the reflective electrode and the semi-transmissive and semi-reflective electrode, causing resonance.

[0263] In the light-emitting device, the optical distance between the reflective electrode and the semi-transmitting / semi-reflective electrode can be changed by changing the thickness of the transparent conductive film or the above-mentioned composite material, carrier transport material, etc. This makes it possible to intensify light of a resonant wavelength and attenuate light of a non-resonant wavelength between the reflective electrode and the semi-transmitting / semi-reflective electrode.

[0264] Note that, since the light reflected by the reflective electrode and returned (first reflected light) significantly interferes with the light (first incident light) that directly enters the semi-transmissive / semi-reflective electrode from the light-emitting layer, it is preferable to adjust the optical distance between the reflective electrode and the light-emitting layer to (2n-1)λ / 4 (where n is a natural number of 1 or more, and λ is the wavelength of the light emission to be amplified). By adjusting the optical distance, the phases of the first reflected light and the first incident light can be matched, thereby further amplifying the light emission from the light-emitting layer.

[0265] In the above configuration, the EL layer may have a structure having multiple light-emitting layers or a structure having a single light-emitting layer. For example, it may be combined with the above-mentioned tandem light-emitting device configuration, in which multiple EL layers are provided in one light-emitting device with a charge-generating layer sandwiched therebetween, and one or more light-emitting layers are formed in each EL layer.

[0266] The microcavity structure makes it possible to increase the light emission intensity of a specific wavelength in the front direction, thereby reducing power consumption. In the case of a light-emitting device that displays images using four sub-pixels of red, yellow, green, and blue, the yellow light emission has the effect of improving brightness, and the microcavity structure that matches the wavelength of each color can be applied to all sub-pixels, resulting in a light-emitting device with good characteristics.

[0267] The light-emitting device in this embodiment can have good characteristics because it uses the light-emitting device described in Embodiment 1. Specifically, the light-emitting device described in Embodiment 1 has good luminous efficiency, so that it can be a light-emitting device with low power consumption.

[0268] Up to this point, active matrix light-emitting devices have been described. From here on, passive matrix light-emitting devices will be described. Figures 5A and 5B show a passive matrix light-emitting device manufactured by applying the present invention. Note that Figure 5A is a perspective view of the light-emitting device, and Figure 5B is a cross-sectional view of Figure 5A taken along the dashed-dotted line X-Y. In Figure 5, an EL layer 955 is provided between an electrode 952 and an electrode 956 on a substrate 951. The edge of the electrode 952 is covered with an insulating layer 953. A partition layer 954 is provided on the insulating layer 953. The sidewalls of the partition layer 954 are inclined such that the distance between one sidewall and the other sidewall becomes narrower as the distance approaches the substrate surface. That is, the cross section of the partition layer 954 in the short side direction is trapezoidal, and the bottom side (the side facing the same direction as the surface of the insulating layer 953 and in contact with the insulating layer 953) is shorter than the top side (the side facing the same direction as the surface of the insulating layer 953 and not in contact with the insulating layer 953). By providing the partition layer 954 in this manner, defects in the light-emitting device due to static electricity or the like can be prevented. Furthermore, the light-emitting device described in Embodiment 1 is used in a passive matrix light-emitting device, and the light-emitting device can have high reliability or consume low power.

[0269] The light emitting device described above is capable of individually controlling a large number of minute light emitting devices arranged in a matrix, and is therefore suitable for use as a display device for displaying images.

[0270] This embodiment mode can be freely combined with other embodiment modes.

[0271] Embodiment 3 In this embodiment, another example of a light-emitting device according to one embodiment of the present invention using the light-emitting device described in Embodiment 1 will be described.

[0272] As shown in FIG. 63A , the light-emitting device of this embodiment has pixels 208 each having a light-emitting device 207 and a color conversion layer 205, and light emitted from the light-emitting device 207 is incident on the color conversion layer 205. That is, the color conversion layer 205 is provided on the optical path along which the light emitted by the light-emitting device 207 reaches the outside of the light-emitting device. The light-emitting device 207 has an EL layer 202 between an anode 201 and a cathode 203. Furthermore, the color conversion layer 205 preferably contains quantum dots, which have the function of absorbing incident light and emitting light of a predetermined wavelength. When the color conversion layer 205 contains quantum dots, the peak width of the emission spectrum is narrow, and light emission with good color purity can be obtained.

[0273] The color conversion layer 205 contains a substance that absorbs incident light and emits light of a predetermined wavelength. The substance that emits light of a predetermined wavelength can be a variety of light-emitting substances, such as inorganic or organic materials that exhibit photoluminescence. Quantum dots (QDs), which are inorganic materials, have a narrow peak width in their emission spectrum, as described above, and can emit light with excellent color purity. Furthermore, because they are inorganic materials, they are inherently stable and have a theoretical internal quantum efficiency of nearly 100%, making them suitable for these reasons.

[0274] The color conversion layer 205 containing quantum dots can be formed by applying a resin or solvent in which quantum dots are dispersed, drying, and baking. Sheets with pre-dispersed quantum dots have also been developed. The color conversion layer 205 can be applied to the surface by a droplet ejection method such as inkjet printing, followed by drying, baking, or solidification, followed by etching using photolithography or the like.

[0275] Examples of quantum dots include nano-sized particles such as Group 14 elements, Group 15 elements, Group 16 elements, compounds consisting of multiple Group 14 elements, compounds of an element belonging to Groups 4 to 14 and a Group 16 element, compounds of a Group 2 element and a Group 16 element, compounds of a Group 13 element and a Group 15 element, compounds of a Group 13 element and a Group 17 element, compounds of a Group 14 element and a Group 15 element, compounds of a Group 11 element and a Group 17 element, iron oxides, titanium oxides, chalcogenide spinels, various semiconductor clusters, and metal halide perovskites.

[0276] Specifically, cadmium selenide (CdSe), cadmium sulfide (CdS), cadmium telluride (CdTe), zinc selenide (ZnSe), zinc oxide (ZnO), zinc sulfide (ZnS), zinc telluride (ZnTe), mercury sulfide (HgS), mercury selenide (HgSe), mercury telluride (HgTe), indium arsenide (InAs), indium phosphide (InP), gallium arsenide (GaAs), phosphorus Gallium nitride (GaP), indium nitride (InN), gallium nitride (GaN), indium antimonide (InSb), gallium antimonide (GaSb), aluminum phosphide (AlP), aluminum arsenide (AlAs), aluminum antimonide (AlSb), lead(II) selenide (PbSe), lead(II) telluride (PbTe), lead(II) sulfide (PbS), indium selenide (In ２ Se ３ ), indium telluride (In ２ Te ３ ), indium sulfide (In ２ S ３ ), gallium selenide (Ga ２ Se ３ ), arsenic(III) sulfide (As ２ S ３ ), arsenic(III) selenide (As ２ Se ３ ), arsenic(III) telluride (As ２ Te ３ ), antimony(III) sulfide (Sb ２ S ３ ), antimony selenide (III) (Sb ２ Se ３), antimony(III) telluride (Sb ２ Te ３ ), bismuth(III) sulfide (Bi ２ S ３ ), bismuth selenide (III) (Bi ２ Se ３ ), bismuth(III) telluride (Bi ２ Te ３ ), silicon (Si), silicon carbide (SiC), germanium (Ge), tin (Sn), selenium (Se), tellurium (Te), boron (B), carbon (C), phosphorus (P), boron nitride (BN), boron phosphide (BP), boron arsenide (BAs), aluminum nitride (AlN), aluminum sulfide (Al ２ S ３ ), barium sulfide (BaS), barium selenide (BaSe), barium telluride (BaTe), calcium sulfide (CaS), calcium selenide (CaSe), calcium telluride (CaTe), beryllium sulfide (BeS), beryllium selenide (BeSe), beryllium telluride (BeTe), magnesium sulfide (MgS), magnesium selenide (MgSe), germanium sulfide (GeS), germanium selenide (GeSe), germanium telluride (GeTe), tin(IV) sulfide (SnS ２ ), tin(II) sulfide (SnS), tin(II) selenide (SnSe), tin(II) telluride (SnTe), lead(II) oxide (PbO), copper(I) fluoride (CuF), copper(I) chloride (CuCl), copper(I) bromide (CuBr), copper(I) iodide (CuI), copper(I) oxide (Cu ２ O), copper(I) selenide (Cu ２ Se), nickel(II) oxide (NiO), cobalt(II) oxide (CoO), cobalt(II) sulfide (CoS), triiron tetroxide (Fe ３ O ４ ), iron(II) sulfide (FeS), manganese(II) oxide (MnO), molybdenum(IV) sulfide (MoS ２ ), vanadium(II) oxide (VO), vanadium(IV) oxide (VO ２ ), tungsten(IV) oxide (WO ２ ), tantalum (V) oxide (Ta ２ O ５), titanium oxide (TiO ２ , Ti ２ O ５ , Ti ２ O ３ , Ti ５ O ９ etc.), zirconium oxide (ZrO ２ ), silicon nitride (Si ３ N ４ ), germanium nitride (Ge ３ N ４ ), aluminum oxide (Al ２ O ３ ), barium titanate (BaTiO ３ ), compounds of selenium, zinc and cadmium (CdZnSe), compounds of indium, arsenic and phosphorus (InAsP), compounds of cadmium, selenium and sulfur (CdSeS), compounds of cadmium, selenium and tellurium (CdSeTe), compounds of indium, gallium and arsenic (InGaAs), compounds of indium, gallium and selenium (InGaSe), compounds of indium, selenium and sulfur (InSeS), compounds of copper, indium and sulfur (e.g. CuInS ２ ) and combinations thereof, but are not limited to these. Also, so-called alloy quantum dots, in which the composition is expressed in any ratio, may be used. For example, CdS ｘ Se （１−ｘ） Alloy quantum dots represented by the formula (x is any number between 0 and 1) can change the emission wavelength by changing x, and are therefore an effective means for obtaining blue light emission.

[0277] Quantum dot structures include core, core-shell, and core-multishell types, and any of these may be used. However, by covering the core with a shell made of another inorganic material with a wider band gap, the effects of defects or dangling bonds present on the nanocrystal surface can be reduced. This significantly improves the quantum efficiency of light emission, so core-shell or core-multishell quantum dots are preferred. Examples of shell materials include zinc sulfide (ZnS) and zinc oxide (ZnO).

[0278] Furthermore, quantum dots have a high proportion of surface atoms, making them highly reactive and prone to aggregation. Therefore, it is preferable that a protective agent or protective group is attached to the surface of the quantum dots. By attaching the protective agent or providing the protective group, aggregation can be prevented and solubility in a solvent can be increased. It is also possible to reduce reactivity and improve electrical stability. Examples of protective agents (or protective groups) include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether; trialkyl phosphines such as tripropyl phosphine, tributyl phosphine, trihexyl phosphine, and trioctyl phosphine; polyoxyethylene n-octyl phenyl ether and polyoxyethylene n-nonyl phenyl ether; tertiary amines such as tri(n-hexyl)amine, tri(n-octyl)amine, and tri(n-decyl)amine; and organic compounds such as tripropyl phosphine oxide, tributyl phosphine oxide, trihexyl phosphine oxide, trioctyl phosphine oxide, and tridecyl phosphine oxide. Examples of the organic sulfur compounds include phosphorus compounds, polyethylene glycol diesters such as polyethylene glycol dilaurate and polyethylene glycol distearate, organic nitrogen compounds such as nitrogen-containing aromatic compounds such as pyridine, lutidine, collidine and quinolines, aminoalkanes such as hexylamine, octylamine, decylamine, dodecylamine, tetradecylamine, hexadecylamine and octadecylamine, dialkyl sulfides such as dibutyl sulfide, dialkyl sulfoxides such as dimethyl sulfoxide and dibutyl sulfoxide, and sulfur-containing aromatic compounds such as thiophene, higher fatty acids such as palmitic acid, stearic acid and oleic acid, alcohols, sorbitan fatty acid esters, fatty acid-modified polyesters, tertiary amine-modified polyurethanes, and polyethyleneimines.

[0279] QDs have a continuous absorption spectrum extending from their own emission wavelength to shorter wavelengths, with the absorption intensity increasing as the wavelength decreases. Therefore, even in displays requiring multiple emission colors, the luminescent center material contained in the light-emitting device for each color pixel can be the same material as long as it emits the required shortest wavelength (typically blue). This eliminates the need to fabricate separate light-emitting devices for each pixel color, allowing light-emitting devices to be produced relatively inexpensively.

[0280] FIG. 63B shows, as an example, pixels that emit light of three colors: blue, green, and red. 208B is a first pixel that emits blue light. The first pixel 208B has an anode 201B and a cathode 203, and the electrode that emits light is a light-transmitting electrode. One of the anode 201B and the cathode 203 may be a reflective electrode, and the other may be a semi-transparent / semi-reflective electrode. Similarly, a second pixel 208G that emits green light and a third pixel 208R that emits red light are also shown, each having an anode 201G and a cathode 203, and an anode 201R and a cathode 203, respectively. FIG. 63B illustrates a configuration in which the anodes 201B, 201G, and 201R are reflective electrodes, and the cathode 203 is a semi-transparent / semi-reflective electrode. The anodes 201B to 201R are formed on an insulator 200. Furthermore, in order to prevent light from mixing with adjacent pixels, a black matrix 206 is preferably provided between the pixels. The black matrix 206 may also serve as a partition wall when forming a color conversion layer by an inkjet method or the like.

[0281] FIG. 63C also shows pixels that emit four colors of light: blue, green, red, and white. 208W is a fourth pixel that emits white light. The fourth pixel 208W has an anode 201W and a cathode 203, one of which is an anode and the other a cathode. Alternatively, one of these may be a reflective electrode and the other a semi-transparent / semi-reflective electrode. The anode 201W is formed on an insulator 200. It is also preferable to provide a black matrix 206 between pixels to prevent light from mixing with adjacent pixels. The black matrix 206 may also serve as a partition when forming a color conversion layer using an inkjet method or the like.

[0282] An EL layer 202 is sandwiched between the anodes 201B, 201G, 201R, and 201W and the cathode 203 in the first to fourth pixels 208B to 208W. The EL layer 202 may be common to the first to fourth pixels 208B to 208W or may be separate, but a common EL layer 202 for multiple pixels is easier to manufacture and more cost-effective. The EL layer 202 is usually composed of multiple layers with separate functions, but some of the layers may be shared by multiple pixels and some may be independent for each pixel.

[0283] The first pixel 208B to the fourth pixel 208W have a first light-emitting device 207B, a second light-emitting device 207G, a third light-emitting device 207R, and a fourth light-emitting device 207W, each of which is configured with an anode, a cathode, and an EL layer. Note that Figures 63B and 63C show an example of a configuration in which the first pixel 208B to the fourth pixel 208W have a common EL layer 202.

[0284] The first light-emitting device 207B to the fourth light-emitting device 207W can be light-emitting devices with a microresonant structure by using a reflective electrode for either the anode or cathode and a semi-transparent / semi-reflective electrode for the other. The wavelength at which light can be resonated is determined by the optical distance 209 between the surface of the reflective electrode and the surface of the semi-transparent / semi-reflective electrode. Setting this optical distance 209 to an integer multiple of λ / 2, where λ is the wavelength at which light is desired to be resonated, can amplify light of wavelength λ. The optical distance 209 can be adjusted by using the hole injection layer, hole transport layer, or transparent electrode layer formed on the reflective electrode as part of the electrode in the EL layer. In the light-emitting devices shown in Figures 63B and 63C, the EL layer is common to the first light-emitting device 207B to the fourth light-emitting device 207W, and the luminescent center material is also the same. Therefore, the optical distance 209 of the light-emitting device is common to the first pixel 208B to the fourth pixel 208W, allowing for easy formation. When the EL layer 202 is formed separately for each pixel, the optical distance 209 may be formed in accordance with the light from the EL layer.

[0285] The protective layer 204 is provided on the cathode 203. The protective layer 204 may also be provided to protect the first to fourth light-emitting devices 207B to 207W from substances or environments that may have adverse effects on them. The protective layer 204 can be made of an oxide, a nitride, a fluoride, a sulfide, a ternary compound, a metal, a polymer, or the like. For example, a material containing aluminum oxide, hafnium oxide, hafnium silicate, lanthanum oxide, silicon oxide, strontium titanate, tantalum oxide, titanium oxide, zinc oxide, niobium oxide, zirconium oxide, tin oxide, yttrium oxide, cerium oxide, scandium oxide, erbium oxide, vanadium oxide, indium oxide, or the like; a material containing aluminum nitride, hafnium nitride, silicon nitride, tantalum nitride, titanium nitride, niobium nitride, molybdenum nitride, zirconium nitride, gallium nitride, or the like; a nitride containing titanium and aluminum; an oxide containing titanium and aluminum; an oxide containing aluminum and zinc; a sulfide containing manganese and zinc; a sulfide containing cerium and strontium; an oxide containing erbium and aluminum; an oxide containing yttrium and zirconium;

[0286] Note that, since the first pixel 208B emits light without passing through a color conversion layer, it is preferable that it be a pixel that emits blue light, which has the highest energy among the three primary colors of light. For the same reason, if the first to fourth light-emitting devices 207B to 207W emit light of the same color, it is preferable that they emit blue light. In this case, it is cost-effective for the luminescent center substances contained in these light-emitting devices to be the same substance, but different luminescent center substances may also be used.

[0287] Furthermore, when separate light-emitting devices are not fabricated for each pixel color, the light emitted by the light-emitting center substance of the light-emitting device preferably emits blue light (the peak wavelength of the emission spectrum is 440 nm to 520 nm, preferably about 440 nm to 480 nm). The peak wavelength of the emission spectrum of the light-emitting center 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 about 3, in order to avoid discrepancies with the emission spectrum of the light-emitting device, the relative dielectric constant of the solvent for putting the light-emitting center substance into a solution state is preferably 1 to 10 at room temperature, more preferably 2 to 5. Specific examples include hexane, benzene, toluene, diethyl ether, ethyl acetate, chloroform, chlorobenzene, and dichloromethane. Furthermore, a commonly used solvent having a relative dielectric constant of 2 to 5 at room temperature, high solubility, and high solubility is more preferred, such as toluene or chloroform.

[0288] The first color conversion layer 205G contains a substance that absorbs light from the second light-emitting device 207G and emits light. The light emitted from the second light-emitting device 207G enters the first color conversion layer 205G and is converted into long-wavelength green light (with a peak wavelength in the emission spectrum of 500 nm to 600 nm, preferably 500 nm to 560 nm) before being emitted. 205R is also a color conversion layer, and the second color conversion layer 205R contains a substance that absorbs light from the third light-emitting device 207R and emits light. The light emitted from the third light-emitting device 207R enters the second color conversion layer 205R and is converted into long-wavelength red light (with a peak wavelength in the emission spectrum of 600 nm to 750 nm, preferably approximately 610 nm to 700 nm) before being emitted. It is preferable that the first color conversion layer 205G and the second color conversion layer 205R contain a color conversion substance such as QD at a concentration that sufficiently absorbs light from the light-emitting device and minimizes the transmission of light from the light-emitting device.

[0289] The third color conversion layer 205W is also a color conversion layer, and contains a substance that absorbs light from the fourth light-emitting device 207W and emits light. The light emitted from the fourth light-emitting device 207W is incident on the third color conversion layer 205W, converted into long-wavelength yellow light (with a peak wavelength of approximately 560 nm to 610 nm, preferably 580 nm to 595 nm), and then emitted. The third color conversion layer 205W contains at least one or more rare earth elements, such as europium, cerium, and yttrium, and can efficiently convert blue light into yellow light. The third color conversion layer 205W contains a color conversion substance that allows it to adequately transmit light from the light-emitting device. The light converted by the third color conversion layer 205W and the light from the light-emitting device that has passed through the third color conversion layer 205W are mixed to produce white light.

[0290] Each of these pixels may further include a color filter.

[0291] 64A to 64C show a configuration in which a structure 205B having a function of scattering light emitted from a first light-emitting device 207B is provided in a first pixel 208B. The structure 205B having a function of scattering light emitted from the first light-emitting device 207B may be a layer containing a first substance that scatters light emitted from the first light-emitting device as in Figures 64A and 64B, or may be a configuration having a structure that scatters light emitted from the first light-emitting device as in Figure 64C.

[0292] Figures 65A to 65C show modified examples. Figure 65A shows an embodiment in which, instead of the light-scattering structure 225B in Figure 64A, a layer (color filter 215B) also functions as a blue color filter. Figures 65B and 65C show an embodiment in which both the light-scattering structure 225B and the blue color filter 215B are included. Note that the blue color filter 215B may be formed in contact with the light-scattering structure 225B, as in Figures 65B and 65C, or it may be formed on another structure, such as an encapsulation substrate. This allows the light-emitting device to scatter light with directionality while further improving color purity. Furthermore, reflection of external light can be suppressed, resulting in a better display.

[0293] The light from the first pixel 208B can be made to have low directionality by emitting the light from the first light-emitting device 207B via the structure 225B, which reduces the difference in orientation characteristics depending on the color, making it possible to provide a light-emitting device with high display quality.

[0294] 66A and 66B show a light-emitting device according to one embodiment of the present invention, which includes means 210G and 210R for imparting directionality to light emitted from the first color conversion layer. Any means may be used to impart directionality to light emitted from the first color conversion layer. For example, semi-transmissive, semi-reflective layers may be formed on both sides of the color conversion layer to form a microresonator structure. Note that FIG. 66A shows an embodiment in which semi-transmissive, semi-reflective layers are formed above and below the color conversion layer, while FIG. 66B shows an embodiment in which the semi-transmissive, semi-reflective layer on the light-emitting device side of the color conversion layer also serves as the cathode (semi-transmissive, semi-reflective electrode) of the light-emitting device.

[0295] The light from the second pixel 208G and the third pixel 208R can be made highly directional by providing means 210G and 210R for imparting directionality to the light emitted from the color conversion layer, respectively, which reduces the difference in orientation characteristics depending on the color, resulting in a light emitting device with high display quality.

[0296] Here, when the light-absorbing and emitting substance contained in the color conversion layer is QDs, adjusting the refractive index of the color conversion layer to an appropriate range, i.e., by dispersing QDs in a resin with an appropriate refractive index, more light emitted from the light-emitting layer can reach the color conversion layer. Typically, layers provided in contact with a translucent electrode for the purpose of improving light extraction efficiency are made of materials with relatively high refractive indices. However, the selection of organic compounds with refractive indices higher than those of many organic compounds is limited. The inventors have discovered that the refractive index of the resin exhibiting the light extraction efficiency improvement effect can be lowered by using a light-emitting device having the configuration described in embodiment 1. Specifically, in a comparative pixel using a light-emitting device without a low-refractive index layer within the EL layer, the amount of light reaching the color conversion layer reached its maximum when the refractive index of the resin dispersing the QDs was 2.20 or higher. In contrast, in a pixel using a light-emitting device with a low-refractive index layer within the EL layer, the maximum value was reached when the refractive index of the resin dispersing the QDs was 2.10 or higher, and the amount of light reaching the color conversion layer was improved over a wide range.

[0297] In this way, it was found that by combining a light-emitting device having a low refractive index layer with a color conversion layer using QDs, not only is the efficiency improved by the low refractive index layer achieved, but the range of resins available for dispersing the QDs can also be expanded.

[0298] The fact that the refractive index is low means that there is a wide range of options for selecting a material that satisfies other required performances. The configuration of one embodiment of the present invention provides various benefits, such as obtaining a light-emitting device with higher efficiency by selecting a resin with good light-transmitting properties, obtaining a light-emitting device with higher reliability by selecting a resin with good durability, and obtaining a light-emitting device with low manufacturing costs by using an inexpensive resin.

[0299] The same effect can be achieved by bonding the color conversion layer and the light-emitting device with a resin having an appropriate refractive index. As a result, the amount of light reaching the color conversion layer increases, making it possible to fabricate a highly efficient light-emitting device. The resin having the appropriate refractive index may also serve as the protective layer 204, or may be further provided between the protective layer 204 and the color conversion layer. The refractive index of the resin is set to be similar to the refractive index of the resin in which the QDs are dispersed.

[0300] Furthermore, lowering the refractive index of the resin in which QDs are dispersed can also be expected to improve the extraction efficiency of light emitted from the color conversion layer using QDs. When light is irradiated into the atmosphere from a dielectric with a refractive index greater than 1, a light trapping effect occurs according to Snell's law, and this light trapping effect decreases as the refractive index decreases. Therefore, lowering the refractive index of the resin in which QDs are dispersed improves the light extraction efficiency of the light emitted from the color conversion layer using QDs.

[0301] In devices with a low refractive index layer inside the EL layer, using a resin with a low refractive index to disperse QDs not only increases the amount of light reaching the QD-based color conversion layer, but also increases the amount of light emitted from the QD-based color conversion layer to the outside of the device, making it possible to fabricate highly efficient color conversion light-emitting devices.

[0302] In a light-emitting device having such a configuration, the amount of light that reaches the color conversion layer is the amount that excludes optical losses due to absorption by the electrodes, optical losses due to evanescent modes, and optical losses due to light confinement resulting from the refractive index difference between the bonded resin and the light-emitting device. Therefore, it is necessary to reduce these losses. The light-emitting device described in embodiment 1 can reduce these losses and further significantly amplify light of a specific wavelength (preferably blue light or light of a wavelength shorter than that in the case of the light-emitting device of this embodiment), thereby enabling the light-emitting device of this embodiment to have very good characteristics.

[0303] The structure of this embodiment mode can be freely combined with the structures of other embodiments mode.

[0304] Embodiment 4 [Light-Emitting Device] Hereinafter, another example of a light-emitting device according to one embodiment of the present invention using the above light-emitting device and a manufacturing method thereof will be described.

[0306] 14A is a schematic top view of a light-emitting device 450 of one embodiment of the present invention. The light-emitting device 450 includes a plurality of red light-emitting devices 110R, a plurality of green light-emitting devices 110G, and a plurality of blue light-emitting devices 110B. In FIG. 14A, the light-emitting regions of the light-emitting devices are labeled with R, G, and B to easily distinguish the light-emitting devices from one another.

[0307] The light-emitting devices 110R, 110G, and 110B are arranged in a matrix. Fig. 14A shows a so-called stripe arrangement in which light-emitting devices of the same color are arranged in one direction. Note that the arrangement of the light-emitting devices is not limited to this, and arrangements such as a delta arrangement or a zigzag arrangement may also be used, or a pentile arrangement may also be used.

[0308] The light emitting devices 110R, 110G, and 110B are arranged in the X direction. In the Y direction intersecting the X direction, light emitting devices of the same color are arranged.

[0309] The light emitting device 110R, the light emitting device 110G, and the light emitting device 110B are light emitting devices having the above-described configuration.

[0310] 14B is a schematic cross-sectional view corresponding to the dashed dotted line A1-A2 in FIG. 14A, and FIG. 14C is a schematic cross-sectional view corresponding to the dashed dotted line B1-B2.

[0311] 14B shows cross sections of the light-emitting device 110R, the light-emitting device 110G, and the light-emitting device 110B. The light-emitting device 110R has a first electrode 101R, an EL layer 120R, an EL layer 121, and a second electrode 102. The light-emitting device 110G has a first electrode 101G, an EL layer 120G, an EL layer (electron injection layer) 115, and a second electrode 102. The light-emitting device 110B has a first electrode 101B, an EL layer 120B, an EL layer 121, and a second electrode 102. The EL layer 121 and the second electrode 102 are provided in common to the light-emitting device 110R, the light-emitting device 110G, and the light-emitting device 110B. The EL layer 121 can also be referred to as a common layer.

[0312] The EL layer 120R of the light-emitting device 110R contains a light-emitting organic compound that emits light having an intensity in at least a red wavelength range. The EL layer 120G of the light-emitting device 110G contains a light-emitting organic compound that emits light having an intensity in at least a green wavelength range. The EL layer 120B of the light-emitting device 110B contains a light-emitting organic compound that emits light having an intensity in at least a blue wavelength range. At least one of the light-emitting devices 110R, 110G, and 110B is a light-emitting device according to one embodiment of the present invention, and it is preferable that the light-emitting device is the light-emitting device 110B.

[0313] The EL layer 120R, the EL layer 120G, and the EL layer 120B each have at least a light-emitting layer and a hole-transporting layer, and may also have one or more of an electron-injecting layer, an electron-transporting layer, a hole-injecting layer, a carrier-blocking layer, an exciton-blocking layer, and the like. The EL layer 121 may not have a light-emitting layer. The EL layer 121 is preferably an electron-injecting layer. Note that if the electron-transporting layer also serves as an electron-injecting layer, the EL layer 121 may not be provided.

[0314] The first electrode 101R, the first electrode 101G, and the first electrode 101B are provided for each light-emitting device. The second electrode 102 and the EL layer 121 are provided as a continuous layer common to each light-emitting device. The hole transport layer in the EL layer 120 is interrupted between light-emitting devices emitting different colors of light, but preferably has the same configuration.

[0315] A conductive film that is transparent to visible light is used for either the first electrode 101 or the second electrode 102, and a conductive film that is reflective is used for the other. By making the first electrode 101 light-transmitting and the second electrode 102 reflective, a bottom-emission display device can be obtained. Conversely, by making each pixel electrode reflective and the second electrode 102 light-transmitting, a top-emission display device can be obtained. Note that by making both each pixel electrode and the second electrode 102 light-transmitting, a dual-emission display device can also be obtained. The light-emitting device of one embodiment of the present invention is suitable for a top-emission light-emitting device.

[0316] An insulating layer 124 is provided to cover the end portions of the first electrode 101R, the first electrode 101G, and the first electrode 101B. The end portions of the insulating layer 124 preferably have a tapered shape. Note that the insulating layer 124 does not have to be provided if it is not necessary.

[0317] The EL layer 120R, the EL layer 120G, and the EL layer 120B each have a region in contact with the upper surface of the pixel electrode and a region in contact with the surface of the insulating layer 124. In addition, the ends of the EL layer 120R, the EL layer 120G, and the EL layer 120B are located on the insulating layer 124.

[0318] FIG. 69 is a modified example of FIG. 14B . In FIG. 69 , the ends of the first electrode 101R, the first electrode 101G, and the first electrode 101B have a tapered shape that widens toward the substrate, improving coverage of films formed thereon. Furthermore, the ends of the first electrode 101R, the first electrode 101G, and the first electrode 101B are covered with the EL layer 120R, the EL layer 120G, and the EL layer 120B, respectively. A sacrificial layer 107 is formed covering the EL layer. This serves to prevent damage to the EL layer during etching by photolithography. An insulating layer 108 is provided between the light-emitting device 110R, the light-emitting device 110G, and the light-emitting device 110B. The ends of the insulating layer 108 have a gently tapered shape, which can prevent discontinuities in the EL layer 121 and the second electrode 102 that are subsequently formed.

[0319] As shown in Figures 14B and 69, a gap is provided between the two EL layers between light-emitting devices of different colors. In this manner, it is preferable that the EL layers 120R, 120G, and 120G are arranged so that they do not contact each other. This effectively prevents current from flowing through two adjacent EL layers, which would otherwise cause unintended light emission. This allows for increased contrast and a display device with high display quality to be realized.

[0320] 14C shows an example in which the EL layer 120R is formed in a strip shape so that the EL layer 120R is continuous in the Y direction. By forming the EL layer 120R in a strip shape, space to separate them is not required, and the area of ​​the non-light-emitting region between the light-emitting devices can be reduced, thereby increasing the aperture ratio. Note that while FIG. 14C shows a cross section of the light-emitting device 110R as an example, the light-emitting device 110G and the light-emitting device 110B can also have a similar shape. Note that the EL layer may be separated for each light-emitting device in the Y direction.

[0321] A protective layer 131 is provided on the second electrode 102 to cover the light-emitting device 110R, the light-emitting device 110G, and the light-emitting device 110B. The protective layer 131 has a function of preventing impurities such as water from diffusing from above into each light-emitting device.

[0322] The protective layer 131 may have, for example, a single-layer structure or a stacked structure including at least an inorganic insulating film. Examples of the inorganic insulating film include oxide films or nitride films such as a silicon oxide film, a silicon oxynitride film, a silicon nitride oxide film, a silicon nitride film, an aluminum oxide film, an aluminum oxynitride film, and a hafnium oxide film. Alternatively, the protective layer 131 may be made of a semiconductor material such as indium gallium oxide or indium gallium zinc oxide.

[0323] Alternatively, the protective layer 131 may be a laminated film of an inorganic insulating film and an organic insulating film. For example, a configuration in which an organic insulating film is sandwiched between a pair of inorganic insulating films is preferable. Furthermore, it is preferable that the organic insulating film functions as a planarizing film. This allows the upper surface of the organic insulating film to be flat, thereby improving the coverage of the inorganic insulating film thereon and enhancing the barrier properties. Furthermore, since the upper surface of the protective layer 131 is flat, when a structure (e.g., a color filter, a touch sensor electrode, a lens array, etc.) is provided above the protective layer 131, the influence of uneven shapes caused by the structure below can be reduced, which is preferable.

[0324] 14A also shows a connection electrode 101C that is electrically connected to the second electrode 102. The connection electrode 101C is given a potential (e.g., an anode potential or a cathode potential) to be supplied to the second electrode 102. The connection electrode 101C is provided outside the display area where the light-emitting devices 110R and the like are arranged. In addition, in FIG. 14A, the second electrode 102 is shown by a dashed line.

[0325] The connection electrode 101C can be provided along the periphery of the display area. For example, it may be provided along one side of the periphery of the display area, or it may be provided over two or more sides of the periphery of the display area. That is, when the top surface shape of the display area is rectangular, the top surface shape of the connection electrode 101C can be strip-shaped, L-shaped, U-shaped (square bracket-shaped), square-shaped, or the like.

[0326] Fig. 14D is a schematic cross-sectional view corresponding to dashed line C1-C2 in Fig. 14A. Fig. 14D shows a connection portion 130 where the connection electrode 101C and the second electrode 102 are electrically connected. In the connection portion 130, the second electrode 102 is provided in contact with the connection electrode 101C, and a protective layer 131 is provided covering the second electrode 102. In addition, an insulating layer 124 is provided covering the end of the connection electrode 101C.

[0327] [Manufacturing Method Example 1] An example of a manufacturing method of a display device according to one embodiment of the present invention will be described below with reference to the drawings. Here, the light-emitting device 450 shown in the above configuration example will be described as an example. Figures 15A to 15F are cross-sectional schematic views of each step in the manufacturing method of the display device exemplified below. Also, in Figure 15A and other figures, a cross-sectional schematic view of the connection portion 130 and its vicinity is also shown on the right side.

[0328] Thin films (insulating films, semiconductor films, conductive films, etc.) constituting the display device can be formed using a sputtering method, a chemical vapor deposition (CVD) method, a vacuum evaporation method, a pulsed laser deposition (PLD) method, an atomic layer deposition (ALD) method, etc. CVD methods include a plasma enhanced chemical vapor deposition (PECVD) method and a thermal CVD method. One type of thermal CVD method is a metal organic chemical vapor deposition (MOCVD) method.

[0329] Furthermore, thin films (insulating films, semiconductor films, conductive films, etc.) constituting the display device can be formed by methods such as spin coating, dipping, spray coating, inkjet, dispensing, screen printing, offset printing, doctor knife method, slit coating, roll coating, curtain coating, knife coating, etc.

[0330] Furthermore, when processing the thin film that constitutes the display device, a photolithography method or the like can be used. Alternatively, the thin film may be processed by a nanoimprint method, a sandblasting method, a lift-off method, or the like. Furthermore, the island-shaped thin film may be directly formed by a film formation method using a shielding mask such as a metal mask.

[0331] There are two typical photolithography methods: one is to form a resist mask on the thin film to be processed, process the thin film by etching or the like, and then remove the resist mask; the other is to form a photosensitive thin film, and then process the thin film into the desired shape by exposure and development.

[0332] In photolithography, the light used for exposure may be, for example, i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), or a mixture of these. Other light sources that can be used include ultraviolet light, KrF laser light, ArF laser light, etc. Exposure may also be performed by immersion exposure technology. Extreme ultraviolet (EUV) light, X-rays, etc. may also be used as light for exposure. An electron beam may also be used instead of light for exposure. Extreme ultraviolet light, X-rays, or an electron beam are preferred because they enable extremely fine processing. When exposure is performed by scanning a beam such as an electron beam, a photomask is not required.

[0333] For etching the thin film, dry etching, wet etching, sandblasting, or the like can be used.

[0334] [Preparation of Substrate 100] A substrate having heat resistance sufficient to withstand at least subsequent heat treatment can be used as the substrate 100. When an insulating substrate is used as the substrate 100, a glass substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, an organic resin substrate, or the like can be used. In addition, a semiconductor substrate such as a single crystal semiconductor substrate made of silicon, silicon carbide, or the like, a polycrystalline semiconductor substrate, a compound semiconductor substrate such as silicon germanium, or an SOI substrate can be used.

[0335] In particular, it is preferable to use a substrate in which a semiconductor circuit including semiconductor elements such as transistors is formed on the semiconductor substrate or insulating substrate as the substrate 100. The semiconductor circuit preferably constitutes, for example, a pixel circuit, a gate line driving circuit (gate driver), a source line driving circuit (source driver), etc. In addition to the above, an arithmetic circuit, a memory circuit, etc. may also be constituted.

[0336] [Formation of First Electrodes 101R, 101G, 101B, and Connection Electrode 101C] Next, the first electrode 101R, the first electrode 101G, the first electrode 101B, and the connection electrode 101C are formed on the substrate 100. First, a conductive film that will become an anode (pixel electrode) is formed, a resist mask is formed by photolithography, and unnecessary portions of the conductive film are removed by etching. Then, the resist mask is removed, thereby forming the first electrode 101R, the first electrode 101G, and the first electrode 101B.

[0337] When a conductive film reflective to visible light is used as each pixel electrode, it is preferable to use a material (e.g., silver or aluminum) with as high a reflectivity as possible across the entire wavelength range of visible light. This not only increases the light extraction efficiency of the light-emitting device but also improves color reproducibility. When a conductive film reflective to visible light is used as each pixel electrode, a so-called top-emission light-emitting device can be obtained, in which light is extracted in the direction away from the substrate. When a light-transmitting conductive film is used as each pixel electrode, a so-called bottom-emission light-emitting device can be obtained, in which light is extracted toward the substrate.

[0338] [Formation of Insulating Layer 124] Next, an insulating layer 124 is formed to cover the edges of the first electrode 101R, the first electrode 101G, and the first electrode 101B ( FIG. 15A ). An organic insulating film or an inorganic insulating film can be used as the insulating layer 124. The insulating layer 124 preferably has tapered edges to improve the step coverage of the EL film that will be formed later. In particular, when an organic insulating film is used, it is preferable to use a photosensitive material, as this makes it easier to control the edge shape by adjusting the exposure and development conditions. Note that if the insulating layer 124 is not provided, the distance between light-emitting devices can be further reduced, resulting in a higher-definition light-emitting device.

[0339] [Formation of EL Film 120Rb] Subsequently, an EL film 120Rb, which will later become the EL layer 120R, is formed on the first electrode 101R, the first electrode 101G, the first electrode 101B, and the insulating layer 124.

[0340] The EL film 120Rb has at least a light-emitting layer containing a light-emitting material and a hole-transport layer. Alternatively, the EL film 120Rb may have a laminated structure of one or more films functioning as an electron injection layer, an electron transport layer, a charge generation layer, or a hole-injection layer. The EL film 120Rb can be formed by, for example, a vapor deposition method, a sputtering method, an inkjet method, or the like. However, the method is not limited to these, and the above-described film formation methods can be used as appropriate.

[0341] For example, the EL film 120Rb is preferably a stacked film in which a hole injection layer, a hole transport layer, a light-emitting layer, and an electron transport layer are stacked in this order. In this case, a film including the electron injection layer 115 can be used as the EL layer to be formed later. In the light-emitting device of one embodiment of the present invention, by providing the electron transport layer to cover the light-emitting layer, damage to the light-emitting layer in a later photolithography process or the like can be suppressed, and a highly reliable light-emitting device can be manufactured.

[0342] It is preferable that the EL film 120Rb is formed so as not to be provided on the connection electrode 101C. For example, when the EL film 120Rb is formed by a vapor deposition method (or a sputtering method), it is preferable that the EL film 120Rb is formed using a shielding mask or removed in a subsequent etching step so that the EL film 120Rb is not formed on the connection electrode 101C.

[0343] [Formation of Mask Film 144a] Subsequently, a mask film 144a is formed to cover the EL film 120Rb. The mask film 144a is provided in contact with the upper surface of the connection electrode 101C.

[0344] The mask film 144a can be a film that is highly resistant to the etching process of each EL film, such as the EL film 120Rb, i.e., a film with a large etching selectivity. The mask film 144a can also be a film that has a large etching selectivity with respect to a protective film, such as the protective film 146a described below. Furthermore, the mask film 144a can be a film that can be removed by wet etching, which causes little damage to each EL film.

[0345] The mask film 144a may be, for example, a metal film, an alloy film, a metal oxide film, a semiconductor film, an inorganic insulating film, etc. The mask film 144a may be formed by various film formation methods such as a sputtering method, a vapor deposition method, a CVD method, an ALD method, etc.

[0346] The mask film 144a may be made of a metal material such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, or tantalum, or an alloy material containing such a metal material. In particular, it is preferable to use a low-melting-point material such as aluminum or silver.

[0347] The mask film 144a can be made of a metal oxide such as indium gallium zinc oxide (In—Ga—Zn oxide, also referred to as IGZO). Other examples include indium oxide, indium zinc oxide (In—Zn oxide), indium tin oxide (In—Sn oxide), indium titanium oxide (In—Ti oxide), indium tin zinc oxide (In—Sn—Zn oxide), indium titanium zinc oxide (In—Ti—Zn oxide), and indium gallium tin zinc oxide (In—Ga—Sn—Zn oxide). Alternatively, indium tin oxide containing silicon can be used.

[0348] The present invention can also be applied to a case where, instead of the gallium, an element M (wherein M is one or more elements selected from aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium) is used. In particular, it is preferable that M is one or more elements selected from gallium, aluminum, and yttrium.

[0349] The mask film 144a may be made of an inorganic insulating material such as aluminum oxide, hafnium oxide, or silicon oxide.

[0350] Furthermore, it is preferable to use a material that can be dissolved in a chemically stable solvent for the mask film 144a, at least for the film located at the top of the EL film 120Rb. In particular, a material that dissolves in water or alcohol is suitable for use as the mask film 144a. When forming the mask film 144a, it is preferable to apply the mask film 144a by a wet film formation method while the mask film 144a is dissolved in a solvent such as water or alcohol, and then perform a heat treatment to evaporate the solvent. In this case, performing the heat treatment under a reduced pressure atmosphere is preferable because it allows the solvent to be removed at a low temperature and in a short time, thereby reducing thermal damage to the EL film 120Rb.

[0351] Wet film formation methods that can be used to form the mask film 144a include spin coating, dipping, spray coating, inkjet, dispensing, screen printing, offset printing, doctor knife method, slit coating, roll coating, curtain coating, knife coating, etc.

[0352] The mask film 144a may be made of an organic material such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinyl pyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or alcohol-soluble polyamide resin.

[0353] [Formation of Protective Film 146a] Subsequently, a protective film 146a is formed on the mask film 144a (FIG. 15B).

[0354] The protective film 146a is a film that is used as a hard mask when etching the mask film 144a later. Furthermore, when processing the protective film 146a later, the mask film 144a is exposed. Therefore, a combination of films that have a large etching selectivity relative to each other is selected for the mask film 144a and the protective film 146a. Therefore, a film that can be used for the protective film 146a can be selected depending on the etching conditions for the mask film 144a and the etching conditions for the protective film 146a.

[0355] For example, when dry etching using a gas containing fluorine (also referred to as a fluorine-based gas) is used to etch the protective film 146a, silicon, silicon nitride, silicon oxide, tungsten, titanium, molybdenum, tantalum, tantalum nitride, an alloy containing molybdenum and niobium, an alloy containing molybdenum and tungsten, or the like can be used for the protective film 146a. Here, examples of films that can achieve a large etching selectivity (i.e., a slower etching rate) compared to dry etching using the fluorine-based gas include metal oxide films such as IGZO and ITO, which can be used for the mask film 144a.

[0356] However, the protective film 146a is not limited to this, and can be selected from various materials depending on the etching conditions of the mask film 144a and the etching conditions of the protective film 146a. For example, it can be selected from films that can be used for the mask film 144a.

[0357] The protective film 146a may be, for example, a nitride film, such as silicon nitride, aluminum nitride, hafnium nitride, titanium nitride, tantalum nitride, tungsten nitride, gallium nitride, or germanium nitride.

[0358] Alternatively, an oxide film can be used as the protective film 146a. Typically, an oxide film or an oxynitride film such as silicon oxide, silicon oxynitride, aluminum oxide, aluminum oxynitride, hafnium oxide, or hafnium oxynitride can be used.

[0359] Alternatively, the protective film 146a may be an organic film that can be used for the EL film 120Rb, etc. For example, the same organic film as that used for the EL film 120Rb, EL film 120Gb, or EL film 120Bb may be used for the protective film 146a. Using such an organic film is preferable because it allows the same film-forming equipment to be used for the EL film 120Rb, etc.

[0360] [Formation of Resist Mask 143a] Subsequently, resist masks 143a are formed on the protective film 146a at positions overlapping the first electrode 101R and the connection electrode 101C (FIG. 15C).

[0361] The resist mask 143a can be made of a resist material containing a photosensitive resin, such as a positive resist material or a negative resist material.

[0362] Here, if the resist mask 143a is formed on the mask film 144a without the protective film 146a, there is a risk that the EL film 120Rb will be dissolved by the solvent of the resist material if there are defects such as pinholes in the mask film 144a. By using the protective film 146a, it is possible to prevent such problems from occurring.

[0363] When a film that is less likely to have defects such as pinholes is used as the mask film 144a, the resist mask 143a may be formed directly on the mask film 144a without using the protective film 146a.

[0364] [Etching of Protective Film 146a] Subsequently, a portion of the protective film 146a that is not covered by the resist mask 143a is removed by etching to form a strip-shaped protective layer 147a. At the same time, the protective layer 147a is also formed on the connection electrode 101C.

[0365] When etching the protective film 146a, it is preferable to use etching conditions with a high selectivity so that the mask film 144a is not removed by the etching. The protective film 146a can be etched by wet etching or dry etching, but using dry etching can prevent the pattern of the protective film 146a from shrinking.

[0366] [Removal of Resist Mask 143a] Subsequently, the resist mask 143a is removed (FIG. 15D).

[0367] The resist mask 143a can be removed by wet etching or dry etching. In particular, the resist mask 143a is preferably removed by dry etching (also called plasma ashing) using oxygen gas as an etching gas.

[0368] At this time, the resist mask 143a is removed while the EL film 120Rb is covered with the mask film 144a, so that the influence on the EL film 120Rb is suppressed. In particular, if the EL film 120Rb comes into contact with oxygen, it may have an adverse effect on the electrical characteristics, so this is suitable for use in etching using oxygen gas, such as plasma ashing.

[0369] [Etching of Mask Film 144a] Next, using the protective layer 147a as a mask, a portion of the mask film 144a that is not covered by the protective layer 147a is removed by etching to form a strip-shaped mask layer 145a (FIG. 15E). At this time, the mask layer 145a is also formed on the connection electrode 101C.

[0370] The mask film 144a can be etched by wet etching or dry etching, but dry etching is preferable because it can prevent the pattern from shrinking.

[0371] [Etching of EL film 120Rb and protective layer 147a] Next, while the protective layer 147a is being etched, a portion of the EL film 120Rb that is not covered by the mask layer 145a is simultaneously removed by etching to form a strip-shaped EL layer 120R (FIG. 15F). At this time, the protective layer 147a on the connection electrode 101C is also removed.

[0372] Etching the EL film 120Rb and the protective layer 147a in the same process is preferable because it is possible to simplify the process and reduce the manufacturing cost of the display device.

[0373] In particular, it is preferable to use dry etching using an etching gas that does not contain oxygen as a main component for etching the EL film 120Rb. This makes it possible to suppress deterioration of the EL film 120Rb and realize a highly reliable display device. Examples of etching gases that do not contain oxygen as a main component include CF ４ , C ４ F ８ , SF ６ , CHF ３ , Cl ２ , H ２ O, BCl ３ , H ２ Alternatively, a noble gas such as He may be used. A mixed gas of the above gas and a dilution gas that does not contain oxygen may be used as the etching gas.

[0374] The EL film 120Rb and the protective layer 147a may be etched separately. In this case, the EL film 120Rb may be etched first, or the protective layer 147a may be etched first.

[0375] At this point, the EL layer 120R and the connection electrode 101C are covered with the mask layer 145a.

[0376] [Formation of EL film 120Gb] Next, an EL film 120Gb, which will later become the EL layer 120G, is formed on the mask layer 145a, the insulating layer 124, the first electrode 101G, and the first electrode 101B. At this time, similar to the EL film 120Rb, it is preferable that the EL film 120Gb is not provided on the connection electrode 101C.

[0377] The method for forming the EL film 120Gb can be similar to that described for the EL film 120Rb.

[0378] [Formation of Mask Film 144b] Subsequently, the mask film 144b is formed on the EL film 120Gb. The mask film 144b can be formed in the same manner as the mask film 144a. In particular, it is preferable to use the same material for the mask film 144b as for the mask film 144a.

[0379] At the same time, a mask film 144a is formed on the connection electrode 101C, covering the mask layer 145a.

[0380] [Formation of Protective Film 146b] Next, the protective film 146b is formed on the mask film 144b. The protective film 146b can be formed by the same method as the protective film 146a. In particular, it is preferable that the protective film 146b is made of the same material as the protective film 146a.

[0381] [Formation of Resist Mask 143b] Subsequently, a resist mask 143b is formed on the protective film 146b in a region overlapping with the first electrode 101G and a region overlapping with the connection electrode 101C (FIG. 16A).

[0382] The resist mask 143b can be formed in the same manner as the resist mask 143a.

[0383] [Etching of Protective Film 146b] Subsequently, a portion of the protective film 146b that is not covered by the resist mask 143b is removed by etching to form a strip-shaped protective layer 147b (FIG. 16B). At the same time, the protective layer 147b is also formed on the connection electrode 101C.

[0384] The above description of the protective film 146a can be applied to the etching of the protective film 146b.

[0385] [Removal of Resist Mask 143b] Subsequently, the resist mask 143a is removed. The above description of the resist mask 143a can be applied to the removal of the resist mask 143b.

[0386] [Etching of Mask Film 144b] Next, using protective layer 147b as a mask, a portion of mask film 144b that is not covered by protective layer 147b is removed by etching to form strip-shaped mask layers 145b. At the same time, mask layer 145b is also formed on connection electrode 101C. Mask layer 145a and mask layer 145b are stacked on connection electrode 101C.

[0387] The above description of the mask film 144a can be applied to the etching of the mask film 144b.

[0388] [Etching of EL film 120Gb and protective layer 147b] Next, while the protective layer 147b is being etched, a portion of the EL film 120Gb that is not covered by the mask layer 145b is simultaneously removed by etching to form a strip-shaped EL layer 120G (FIG. 16C). At this time, the protective layer 147b on the connection electrode 101C is also removed.

[0389] The above description of the EL film 120Rb and the protective layer 147a can be applied to the etching of the EL film 120Gb and the protective layer 147b.

[0390] At this time, since the EL layer 120R is protected by the mask layer 145a, it is possible to prevent the EL layer 120R from being damaged in the etching process of the EL film 120Gb.

[0391] In this way, the strip-shaped EL layers 120R and the strip-shaped EL layers 120G can be separately formed with high positional accuracy.

[0392] [Formation of EL Layer 120B] By performing the above steps on the EL film 120Bb (not shown), it is possible to form an island-shaped EL layer 120B and an island-shaped mask layer 145c (FIG. 16D).

[0393] That is, after the EL layer 120G is formed, the EL film 120Bb, mask film 144c, protective film 146c, and resist mask 143c (none of which are shown) are formed in this order. The protective film 146c is then etched to form a protective layer 147c (not shown), and the resist mask 143c is then removed. The mask film 144c is then etched to form a mask layer 145c. The protective layer 147c and the EL film 120Bb are then etched to form the strip-shaped EL layer 120B.

[0394] After the EL layer 120B is formed, a mask layer 145c is also formed on the connection electrode 101C at the same time. A mask layer 145a, a mask layer 145b, and a mask layer 145c are stacked on the connection electrode 101C.

[0395] [Removal of Mask Layers] Next, the mask layers 145a, 145b, and 145c are removed to expose the upper surfaces of the EL layers 120R, 120G, and 120B (FIG. 16E). At the same time, the upper surface of the connection electrode 101C is also exposed.

[0396] The mask layers 145a, 145b, and 145c can be removed by wet etching or dry etching. It is preferable to use a method that minimizes damage to the EL layers 120R, 120G, and 120B. It is particularly preferable to use a wet etching method. For example, it is preferable to use wet etching using a tetramethylammonium hydroxide solution (TMAH), diluted hydrofluoric acid, oxalic acid, phosphoric acid, acetic acid, nitric acid, or a mixture thereof.

[0397] Alternatively, the mask layers 145 a, 145 b, and 145 c may be removed by dissolving them in a solvent such as water or alcohol. Here, various alcohols such as ethyl alcohol, methyl alcohol, isopropyl alcohol (IPA), or glycerin may be used as the alcohol capable of dissolving the mask layers 145 a, 145 b, and 145 c.

[0398] After removing the mask layers 145a, 145b, and 145c, it is preferable to perform drying treatment to remove water contained inside the EL layers 120R, 120G, and 120B and water adsorbed on their surfaces. For example, it is preferable to perform heat treatment in an inert gas atmosphere or a reduced-pressure atmosphere. The heat treatment can be performed at a substrate temperature of 50°C or higher and 200°C or lower, preferably 60°C or higher and 150°C or lower, and more preferably 70°C or higher and 120°C or lower. A reduced-pressure atmosphere is preferable because it enables drying at a lower temperature.

[0399] In this manner, the EL layer 120R, the EL layer 120G, and the EL layer 120B can be separately produced.

[0400] [Formation of Electron Injection Layer 115] Subsequently, the electron injection layer 115 is formed to cover the EL layer 120R, the EL layer 120G, and the EL layer 120B.

[0401] The electron injection layer 115 can be formed by the same method as the EL film 120Rb, etc. When the electron injection layer 115 is formed by a vapor deposition method, it is preferable to form the layer using a shielding mask so that the electron injection layer 115 is not formed on the connection electrode 101C.

[0402] [Formation of Second Electrode 102] Subsequently, the second electrode 102 is formed to cover the electron injection layer 115 and the connection electrode 101C (FIG. 16F).

[0403] The second electrode 102 can be formed by a film formation method such as evaporation or sputtering. Alternatively, a film formed by evaporation and a film formed by sputtering may be stacked. In this case, the second electrode 102 is preferably formed so as to encompass a region where the electron injection layer 115 is formed. That is, the second electrode 102 can have an edge portion overlapping with the second electrode 102. The second electrode 102 is preferably formed using a shielding mask.

[0404] The second electrode 102 is electrically connected to the connection electrode 101C outside the display area.

[0405] [Formation of Protective Layer] Subsequently, a protective layer is formed on the second electrode 102. The inorganic insulating film used for the protective layer is preferably formed by sputtering, PECVD, or ALD. The ALD method is particularly preferred because it has excellent step coverage and is less likely to cause defects such as pinholes. Furthermore, the inkjet method is preferably used for forming the organic insulating film because it can form a uniform film in a desired area.

[0406] Through the above steps, a light-emitting device of one embodiment of the present invention can be manufactured.

[0407] Note that although the above description shows the case where the second electrode 102 and the electron injecting layer 115 are formed to have different top surface shapes, they may be formed in the same region.

[0408] In this embodiment, an example in which the light-emitting device described in Embodiment 1 is used as a lighting device will be described with reference to Fig. 6. Fig. 6B is a top view of the lighting device, and Fig. 6A is a cross-sectional view taken along line e-f in Fig. 6B.

[0409] In the lighting device of this embodiment, an anode 401 is formed on a light-transmitting substrate 400 serving as a support. The anode 401 corresponds to the first electrode 101 in Embodiment 1. When light is extracted from the anode 401 side, the anode 401 is formed of a light-transmitting material.

[0410] A pad 412 for supplying a voltage to the cathode 404 is formed on the substrate 400 .

[0411] An EL layer 403 is formed on the anode 401. The EL layer 403 corresponds to the structure of the EL layer 103 in Embodiment Mode 1. For details of these structures, refer to the description therein.

[0412] A cathode 404 is formed to cover the EL layer 403. The cathode 404 corresponds to the second electrode 102 in Embodiment Mode 1. When light is extracted from the anode 401 side, the cathode 404 is formed of a material with high reflectivity. The cathode 404 is connected to a pad 412 to supply a voltage.

[0413] As described above, the lighting device described in this embodiment has a light-emitting device including the anode 401, the EL layer 403, and the cathode 404. Since the light-emitting device has high emission efficiency, the lighting device in this embodiment can be a lighting device with low power consumption.

[0414] The lighting device is completed by bonding and sealing the substrate 400 on which the light-emitting device having the above structure is formed and the sealing substrate 407 using sealants 405 and 406. Either one of the sealants 405 or 406 may be used. Also, a desiccant may be mixed into the inner sealant 406 (not shown in FIG. 6B ), which can absorb moisture and improve reliability.

[0415] Furthermore, the pad 412 and a portion of the anode 401 can be extended outside the sealing materials 405 and 406 to serve as an external input terminal. An IC chip 420 equipped with a converter or the like may also be provided thereon.

[0416] As described above, the lighting device described in this embodiment mode uses the light-emitting device described in Embodiment Mode 1 as an EL element, and can be a light-emitting device with low power consumption.

[0417] This embodiment mode can be freely combined with other embodiment modes.

[0418] Embodiment 6 In this embodiment, an example of an electronic device including the light-emitting device described in Embodiment 1 as a part thereof will be described. The light-emitting device described in Embodiment 1 has good light-emitting efficiency and low power consumption. As a result, the electronic device described in this embodiment can be an electronic device having a light-emitting portion with low power consumption.

[0419] Examples of electronic devices to which the light-emitting devices are applied include television sets (also called televisions or television receivers), computer monitors, digital cameras, digital video cameras, digital photo frames, mobile phones (also called mobile phones or mobile phone devices), portable game machines, personal digital assistants, sound reproducing devices, large game machines such as pachinko machines, etc. Specific examples of these electronic devices are shown below.

[0420] 7A illustrates an example of a television set. The television set has a display portion 7103 incorporated in a housing 7101. Here, the housing 7101 is supported by a stand 7105. Images can be displayed on the display portion 7103, and the display portion 7103 is configured such that the light-emitting devices described in Embodiment 1 are arranged in a matrix.

[0421] The television set can be operated using an operation switch provided on the housing 7101 or a separate remote control 7110. An operation key 7109 provided on the remote control 7110 can be used to operate a channel or a volume, and an image displayed on the display portion 7103 can be controlled. The remote control 7110 may be provided with a display portion 7107 that displays information output from the remote control 7110. Note that the light-emitting devices described in Embodiment 1 arranged in a matrix can also be applied to the display portion 7107.

[0422] The television device is configured to include a receiver, a modem, etc. The receiver can receive general television broadcasts, and by connecting to a wired or wireless communication network via the modem, it is also possible to perform one-way (from sender to receiver) or two-way (between sender and receiver, or between receivers, etc.) information communication.

[0423] FIG. 7B1 shows a computer including a main body 7201, a housing 7202, a display portion 7203, a keyboard 7204, an external connection port 7205, a pointing device 7206, and the like. Note that this computer is manufactured by using the light-emitting devices described in Embodiment 1 arranged in a matrix for the display portion 7203. The computer of FIG. 7B1 may have a configuration as shown in FIG. 7B2. The computer of FIG. 7B2 is provided with a display portion 7210 instead of the keyboard 7204 and the pointing device 7206. The display portion 7210 is a touch panel type, and input can be performed by operating an input display displayed on the display portion 7210 with a finger or a dedicated pen. The display portion 7210 can display not only an input display but also other images. The display portion 7203 may also be a touch panel. The two screens are connected by a hinge, which can prevent problems such as scratches or breakage of the screens during storage or transportation.

[0424] 7C shows an example of a mobile terminal. The mobile phone includes a display portion 7402 incorporated in a housing 7401, operation buttons 7403, an external connection port 7404, a speaker 7405, a microphone 7406, and the like. Note that the mobile phone has the display portion 7402 in which the light-emitting devices described in Embodiment 1 are arranged in a matrix.

[0425] 7C can be configured so that information can be input by touching the display portion 7402 with a finger or the like. In this case, operations such as making a call or creating an email can be performed by touching the display portion 7402 with a finger or the like.

[0426] The screen of the display portion 7402 has three main modes. The first is a display mode mainly for displaying images, the second is an input mode mainly for inputting information such as characters, and the third is a display+input mode that combines the display mode and the input mode.

[0427] For example, when making a call or creating an email, the display portion 7402 may be set to a character input mode mainly for inputting characters, and characters displayed on the screen may be input. In this case, it is preferable to display a keyboard or number buttons on most of the screen of the display portion 7402.

[0428] In addition, by providing a detection device having a sensor that detects tilt, such as a gyro or acceleration sensor, inside the mobile terminal, the orientation of the mobile terminal (portrait or landscape) can be determined and the screen display of the display portion 7402 can be automatically switched.

[0429] The screen mode can be switched by touching the display portion 7402 or by operating the operation buttons 7403 on the housing 7401. The screen mode can also be switched depending on the type of image displayed on the display portion 7402. For example, if the image signal to be displayed on the display portion is moving image data, the display mode is selected, and if it is text data, the input mode is selected.

[0430] In addition, in the input mode, a signal detected by an optical sensor of the display portion 7402 may be detected, and if there is no input by touch operation on the display portion 7402 for a certain period of time, the screen mode may be controlled to switch from the input mode to the display mode.

[0431] The display portion 7402 can also function as an image sensor. For example, personal authentication can be performed by touching the display portion 7402 with a palm or a finger to capture an image of a palm print, a fingerprint, or the like. Furthermore, by using a backlight that emits near-infrared light or a sensing light source that emits near-infrared light for the display portion, finger veins, palm veins, or the like can also be captured.

[0432] Note that the structure described in this embodiment mode can be used by appropriately combining the structures described in any of Embodiment Modes 1 to 6.

[0433] As described above, the light-emitting device having the light-emitting device described in Embodiment 1 or 2 has a very wide range of application, and this light-emitting device can be applied to electronic devices in a variety of fields. By using the light-emitting device described in Embodiment 1 or 2, electronic devices with low power consumption can be obtained.

[0434] FIG. 8A is a schematic diagram showing an example of a cleaning robot.

[0435] The cleaning robot 5100 has a display 5101 arranged on its top surface, multiple cameras 5102 arranged on its side, a brush 5103, and an operation button 5104. Although not shown, the cleaning robot 5100 is also provided with tires, a suction port, and the like on its bottom surface. The cleaning robot 5100 is also provided with various other sensors, such as an infrared sensor, an ultrasonic sensor, an acceleration sensor, a piezoelectric sensor, an optical sensor, and a gyro sensor. The cleaning robot 5100 is also provided with wireless communication means.

[0436] The cleaning robot 5100 can move by itself, detect dust 5120, and suck up the dust from a suction port provided on the bottom surface.

[0437] The cleaning robot 5100 can also analyze the image captured by the camera 5102 to determine whether there are any obstacles such as walls, furniture, or steps. If the image analysis detects an object that may become tangled in the brush 5103, such as a wire, the cleaning robot 5100 can stop the rotation of the brush 5103.

[0438] The display 5101 can display the remaining battery level, the amount of dust sucked, etc. The route traveled by the cleaning robot 5100 may be displayed on the display 5101. The display 5101 may also be a touch panel, and an operation button 5104 may be provided on the display 5101.

[0439] The cleaning robot 5100 can communicate with a portable electronic device 5140 such as a smartphone. Images captured by the camera 5102 can be displayed on the portable electronic device 5140. This allows the owner of the cleaning robot 5100 to know the state of the room even when they are away from home. In addition, the display on the display 5101 can be confirmed on the portable electronic device such as a smartphone.

[0440] The light-emitting device of one embodiment of the present invention can be used for the display 5101 .

[0441] The robot 2100 shown in FIG. 8B includes a computing device 2110, an illuminance sensor 2101, a microphone 2102, an upper camera 2103, a speaker 2104, a display 2105, a lower camera 2106, an obstacle sensor 2107, and a movement mechanism 2108.

[0442] The microphone 2102 has a function of detecting the user's voice, environmental sounds, etc. The speaker 2104 has a function of emitting sound. The robot 2100 can communicate with the user using the microphone 2102 and the speaker 2104.

[0443] The display 2105 has a function of displaying various information. The robot 2100 can display information desired by the user on the display 2105. The display 2105 may be equipped with a touch panel. The display 2105 may also be a detachable information terminal, which can be installed in a fixed position on the robot 2100 to enable charging and data transfer.

[0444] The upper camera 2103 and the lower camera 2106 have a function of capturing images of the surroundings of the robot 2100. In addition, the obstacle sensor 2107 can detect the presence or absence of an obstacle in the moving direction when the robot 2100 moves forward using the moving mechanism 2108. The robot 2100 can recognize the surrounding environment and move safely using the upper camera 2103, the lower camera 2106, and the obstacle sensor 2107. The light-emitting device of one embodiment of the present invention can be used for the display 2105.

[0445] 8C is a diagram illustrating an example of a goggle-type display. The goggle-type display includes, for example, a housing 5000, a display unit 5001, a speaker 5003, an LED lamp 5004 (including a power switch or an operation switch), a connection terminal 5006, a sensor 5007 (including a function for measuring force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared ray), a microphone 5008, a second display unit 5002, a support unit 5012, and earphones 5013.

[0446] The light-emitting device of one embodiment of the present invention can be used for the display portion 5001 and the second display portion 5002 .

[0447] 9 shows an example in which the light-emitting device described in Embodiment 1 is used in a desk lamp, which is a lighting device. The desk lamp shown in FIG. 9 includes a housing 2001 and a light source 2002, and the lighting device described in Embodiment 5 may be used as the light source 2002.

[0448] 10 shows an example in which the light-emitting device described in Embodiment 1 is used as an indoor lighting device 3001. Since the light-emitting device described in Embodiment 1 has high emission efficiency, it can be used as a lighting device with low power consumption. Furthermore, since the light-emitting device described in Embodiment 1 can be made large, it can be used as a large-area lighting device. Furthermore, since the light-emitting device described in Embodiment 1 is thin, it can be used as a thin lighting device.

[0449] The light-emitting device described in Embodiment 1 can also be mounted on a windshield or dashboard of an automobile. Figure 11 shows one mode in which the light-emitting device described in Embodiment 1 is used on a windshield or dashboard of an automobile. Display regions 5200 to 5203 are displays provided using the light-emitting device described in Embodiment 1.

[0450] The display region 5200 and the display region 5201 are display devices equipped with the light-emitting device described in Embodiment 1 and provided on the windshield of an automobile. The light-emitting device described in Embodiment 1 can be a so-called see-through display device in which the opposite side can be seen through by fabricating the anode and cathode using light-transmitting electrodes. A see-through display can be installed on the windshield of an automobile without obstructing the view. Note that when a transistor or the like for driving is provided, a light-transmitting transistor such as an organic transistor made of an organic semiconductor material or a transistor using an oxide semiconductor is preferably used.

[0451] The display area 5202 is a display device provided in a pillar portion and equipped with the light-emitting device described in Embodiment 1. By displaying an image from an imaging means provided in the vehicle body in the display area 5202, the view blocked by the pillar can be complemented. Similarly, the display area 5203 provided in the dashboard portion can complement the view blocked by the vehicle body by displaying an image from an imaging means provided outside the vehicle, thereby compensating for blind spots and improving safety. By displaying an image to complement the invisible part, safety can be confirmed more naturally and without discomfort.

[0452] The display area 5203 can also provide various other information such as navigation information, speed or RPM, and air conditioning settings. The display items or layout can be changed as needed to suit the user's preferences. This information can also be provided in the display areas 5200 to 5202. The display areas 5200 to 5203 can also be used as lighting devices.

[0453] 12A and 12B show a foldable portable information terminal 5150. The foldable portable information terminal 5150 has a housing 5151, a display area 5152, and a bending portion 5153. Fig. 12A shows the portable information terminal 5150 in an unfolded state. Fig. 12B shows the portable information terminal in a folded state. Although the portable information terminal 5150 has a large display area 5152, it is compact and highly portable when folded.

[0454] The display area 5152 can be folded in half by a bending portion 5153. The bending portion 5153 is composed of an expandable member and multiple support members, and when folding, the expandable member stretches. The bending portion 5153 is folded with a curvature radius of 2 mm or more, preferably 3 mm or more.

[0455] Note that the display region 5152 may be a touch panel (input / output device) equipped with a touch sensor (input device). The light-emitting device of one embodiment of the present invention can be used for the display region 5152.

[0456] 13A to 13C show a foldable portable information terminal 9310. Fig. 13A shows the portable information terminal 9310 in an unfolded state. Fig. 13B shows the portable information terminal 9310 in a state in the process of changing from one of the unfolded state and the folded state to the other. Fig. 13C shows the portable information terminal 9310 in a folded state. The portable information terminal 9310 has excellent portability in a folded state, and has excellent display visibility due to a seamless, wide display area in an unfolded state.

[0457] The display panel 9311 is supported by three housings 9315 connected by hinges 9313. Note that the display panel 9311 may be a touch panel (input / output device) equipped with a touch sensor (input device). Furthermore, the display panel 9311 can be reversibly transformed from an unfolded state to a folded state by bending the two housings 9315 via the hinges 9313. The light-emitting device of one embodiment of the present invention can be used for the display panel 9311.

[0458] In this example, light-emitting devices having at least three layers in the hole transport layer will be described, in which the combinations of high and low refractive indexes of the three layers are changed (light-emitting device 1, comparative light-emitting device 1, and comparative light-emitting device 2). The structural formulas of the organic compounds used in this example are shown below.

[0459]

[0460] (Method of Manufacturing Light-Emitting Device 1) First, a silver (Ag) film was formed on a glass substrate by sputtering to a thickness of 100 nm as a reflective electrode, and then an indium tin oxide containing silicon oxide (ITSO) film was formed by sputtering to a thickness of 10 nm as a transparent electrode to form a first electrode 101. The electrode area was 4 mm ２ The first electrode 101 is a transparent electrode, and can be regarded as the first electrode together with the reflective electrode.

[0461] Next, as a pretreatment for forming a light-emitting device on the substrate, 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.

[0462] Then, 10 −４ The substrate was introduced into a vacuum deposition apparatus whose internal pressure had been reduced to about Pa, and was subjected to vacuum baking at 170° C. for 30 minutes in a heating chamber within the vacuum deposition apparatus, after which the substrate was allowed to cool for about 30 minutes.

[0463] Next, the substrate on which the first electrode 101 was formed was fixed to a substrate holder provided in a vacuum deposition apparatus so that the surface on which the first electrode 101 was formed faced downward. N-(1,1′-biphenyl-2-yl)-N-(3,3″,5′,5″-tetra-t-butyl-1,1′:3′,1″-terphenyl-5-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPoFBi-02) represented by the above structural formula (viii) and an electron acceptor material (OCHD-003) containing fluorine and having a molecular weight of 672 were co-deposited by a deposition method to a thickness of 10 nm on the first electrode 101 in a weight ratio of 1:0.1 (=PCBDBtBB-02:OCHD-003).

[0464] On the hole injection layer 111, a hole transport layer 112 was formed by depositing mmtBumTPoFBi-02 to a thickness of 35 nm as a first layer, 4,4′-bis(dibenzothiophen-4-yl)-4″-(9-phenyl-9H-carbazol-2-yl)triphenylamine (abbreviation: PCBDBtBB-02) represented by the above structural formula (i) to a thickness of 40 nm as a second layer, and mmtBumTPoFBi-02 to a thickness of 35 nm as a third layer.

[0465] Subsequently, PCBDBtBB-02 was vapor-deposited on the hole transport layer 112 to a thickness of 10 nm to form an electron blocking layer.

[0466] Thereafter, 2-(10-phenyl-9-anthracenyl)-benzo[b]naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA) represented by the structural formula (ii) above and 3,10-bis[N-(9-phenyl-9H-carbazol-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b′]bisbenzofuran (abbreviation: 3,10PCA2Nbf(IV)-02) represented by the structural formula (iii) above were co-deposited to a thickness of 25 nm so as to give a weight ratio of 1:0.015 (=Bnf(II)PhA:3,10PCA2Nbf(IV)-02), to form a light-emitting layer 113.

[0467] Thereafter, 2-[3′-(9,9-dimethyl-9H-fluoren-2-yl)-1,1′-biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn) represented by the structural formula (iv) above was deposited to a thickness of 10 nm to form a hole blocking layer, and then 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn) represented by the structural formula (v) above and 8-hydroxyquinolinato-lithium (abbreviation: Liq) represented by the structural formula (vi) above were co-deposited to a thickness of 20 nm in a weight ratio of 1:1 (=mPn-mDMePyPTzn:Liq) to form an electron transport layer 114.

[0468] After forming the electron transport layer 114, lithium fluoride (LiF) was deposited to a thickness of 1 nm to form the electron injection layer 115. Finally, silver (Ag) and magnesium (Mg) were co-deposited at a volume ratio of 1:0.1 and a film thickness of 15 nm to form the second electrode 102 (second electrode), thereby producing the light-emitting device 1. The electrode is semi-transparent and semi-reflective, having the functions of reflecting and transmitting light, and the light-emitting device of this example is a top-emission element that extracts light from the second electrode 102. Furthermore, 4,4′,4″-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) represented by the above structural formula (vii) was deposited to a thickness of 70 nm on the second electrode 102 to improve extraction efficiency.

[0469] (Method of Fabricating Comparative Light-Emitting Device 1) Comparative light-emitting device 1 was fabricated in the same manner as light-emitting device 1, except that the first and third layers in the hole transport layer of light-emitting device 1 were replaced with PCBDBtBB-02 and each had a thickness of 30 nm.

[0470] (Method of Fabricating Comparative Light-Emitting Device 2) Comparative light-emitting device 2 was fabricated in the same manner as light-emitting device 1, except that the second layer in the hole transport layer of light-emitting device 1 was changed to mmtBumTPoFBi-02 and its thickness was set to 60 nm.

[0471] The device structures of light-emitting device 1, comparative light-emitting device 1, and comparative light-emitting device 2 are summarized in the table below.

[0472]

[0473]

[0474] The ordinary light refractive index of PCBDBtBB-02 and mmtBumTPoFBi-02 was measured and the results are shown in Figure 17. The measurements were performed using a spectroscopic ellipsometer (M-2000U manufactured by J.A. Woollam Japan). The measurement samples used were films of approximately 50 nm thickness formed by vacuum deposition of each layer material on a quartz substrate.

[0475] From the figure, it can be seen that PCBDBtBB-02 and mmtBumTPoFBi-02 are a combination in which the difference is 0.2 or more and less than 0.5 in the range of 450 nm to 650 nm.

[0476] The HOMO levels of PCBDBtBB-02 and mmtBumTPoFBi-02 calculated from the results of cyclic voltammetry (CV) measurements were -5.51 eV and -5.43 eV, respectively, when N,N-dimethylformamide (DMF) was used as the solvent. This indicates that the difference in the HOMO levels of PCBDBtBB-02 and mmtBumTPoFBi-02 is 0.1 eV or less. The CV measurements were performed using an electrochemical analyzer (manufactured by BAS Inc., model number: ALS Model 600A or 600C) on a solution prepared by dissolving the material to be measured in a solvent.

[0477] The above-mentioned light-emitting device 1, comparative light-emitting device 1, and comparative light-emitting device 2 were sealed with glass substrates in a glove box with a nitrogen atmosphere to prevent the light-emitting devices from being exposed to the atmosphere (a UV-curable sealant was applied around the elements, UV was irradiated only on the sealant without irradiating the light-emitting devices, and heat-treated at 80°C under atmospheric pressure for 1 hour), and then the initial characteristics of these light-emitting devices were measured.

[0478] The luminance-current density characteristics of light-emitting device 1, comparative light-emitting device 1, and comparative light-emitting device 2 are shown in Fig. 18, their luminance-voltage characteristics in Fig. 19, their current efficiency-luminance characteristics in Fig. 20, their current density-voltage characteristics in Fig. 21, their blue index-luminance characteristics in Fig. 22, and their emission spectra in Fig. 23. ２ The main characteristics in this range are shown in Table 3. The luminance, CIE chromaticity, and emission spectrum were measured using a spectroradiometer (SR-UL1R, manufactured by Topcon Corporation) at room temperature.

[0479] The blue index (BI) is a value obtained by further dividing the current efficiency (cd / A) by the y chromaticity, and is one of the indices that represent the luminous characteristics of blue light emission. The smaller the y chromaticity, the higher the color purity of blue light emission tends to be. Blue light emission with high color purity can express a wide range of blue even with a small luminance component, and the use of blue light emission with high color purity reduces the required luminance to express blue, thereby achieving a reduction in power consumption. Therefore, the BI, which takes into account the y chromaticity, which is one index of blue purity, is preferably used as a means of expressing the efficiency of blue light emission. It can be said that a light-emitting device with a higher BI has better efficiency as a blue light-emitting device used in a display.

[0480]

[0481] 18 to 23 and Table 3 show that light-emitting device 7, which is a light-emitting device of one embodiment of the present invention, is a light-emitting device with excellent current efficiency and blue index (BI) compared to other light-emitting devices. In particular, the BI is very high, at 200 (cd / A / y) or more, and light-emitting device 7 can be said to be a light-emitting device with an especially excellent BI. Therefore, one embodiment of the present invention is particularly suitable as a light-emitting device used in a display.

[0482] In this example, a light-emitting device 10 which is a light-emitting device of one embodiment of the present invention and a comparative light-emitting device 10 will be described. The structural formulae of organic compounds used in this example are shown below.

[0483]

[0484] (Method of Manufacturing the Light-Emitting Device 10) First, a silver (Ag) film was formed on a glass substrate by sputtering to a thickness of 100 nm as a reflective electrode, and then an indium tin oxide containing silicon oxide (ITSO) film was formed on the glass substrate by sputtering to a thickness of 10 nm as a transparent electrode, forming a first electrode 101. The electrode area was 4 mm ２ The first electrode 101 is a transparent electrode, and can be regarded as the first electrode together with the reflective electrode.

[0485] Next, as a pretreatment for forming a light-emitting device on the substrate, 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.

[0486] Then, 10 −４ The substrate was introduced into a vacuum deposition apparatus whose internal pressure had been reduced to about Pa, and was subjected to vacuum baking at 170° C. for 30 minutes in a heating chamber within the vacuum deposition apparatus, after which the substrate was allowed to cool for about 30 minutes.

[0487] Next, the substrate on which the first electrode 101 was formed was fixed to a substrate holder provided in a vacuum deposition apparatus so that the surface on which the first electrode 101 was formed faced downward. N-3′,5′-ditertiarybutyl-1,1′-biphenyl-4-yl-N-1,1′-biphenyl-2-yl-9,9,-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBuBioFBi) represented by the above structural formula (ix) and an electron acceptor material (OCHD-003) having a molecular weight of 672 and containing fluorine were co-deposited by a deposition method to a thickness of 10 nm on the first electrode 101 so as to give a weight ratio of 1:0.1 (=mmtBuBioFBi:OCHD-003), thereby forming a hole injection layer 111.

[0488] On the hole injection layer 111, a hole transport layer 112 was formed by depositing mmtBuBioFBi to a thickness of 30 nm as a first layer, 4,4′-diphenyl-4″-(7;2′-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B-03) represented by the above structural formula (x) to a thickness of 50 nm as a second layer, and mmtBuBioFBi to a thickness of 40 nm as a third layer.

[0489] Subsequently, N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP) represented by the above structural formula (xi) was vapor-deposited on the hole-transporting layer 112 to a thickness of 10 nm to form an electron-blocking layer.

[0490] Thereafter, 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: αN-βNPAnth) represented by the structural formula (xii) above and 3,10-bis[N-(9-phenyl-9H-carbazol-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b′]bisbenzofuran (abbreviation: 3,10PCA2Nbf(IV)-02) represented by the structural formula (iii) above were co-deposited to a thickness of 20 nm so as to give a weight ratio of 1:0.015 (=αN-βNPAnth:3,10PCA2Nbf(IV)-02), to form a light-emitting layer 113.

[0491] Thereafter, 6-(1,1′-biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm) represented by the structural formula (xiv) above was deposited to a thickness of 10 nm to form a hole blocking layer, and then 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn) represented by the structural formula (v) above and 8-hydroxyquinolinatolithium (abbreviation: Liq) represented by the structural formula (vi) above were co-deposited to a thickness of 20 nm in a weight ratio of 1:1 (=mPn-mDMePyPTzn:Liq) to form an electron transport layer 114.

[0492] After forming the electron transport layer 114, lithium fluoride (LiF) was deposited to a thickness of 1 nm to form the electron injection layer 115. Finally, a second electrode 102 (second electrode) was formed by co-evaporating silver (Ag) and magnesium (Mg) at a volume ratio of 1:0.1 and a film thickness of 15 nm, thereby producing the light-emitting device 10. The electrode is semi-transparent and semi-reflective, having the functions of reflecting and transmitting light, and the light-emitting device of this example is a top-emission element that extracts light from the second electrode 102. Furthermore, 4,4′,4″-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) represented by the above structural formula (vii) was evaporated to a thickness of 70 nm on the second electrode 102 to improve extraction efficiency.

[0493] (Method of Fabricating Comparative Light-Emitting Device 10) Comparative light-emitting device 10 was fabricated in the same manner as light-emitting device 10, except that the thickness of the first layer in the hole transport layer of light-emitting device 10 was 35 nm and the second layer was formed of mmtBuBioFBi.

[0494] The device structures of the light-emitting device 10 and the comparative light-emitting device 10 are summarized in the table below.

[0495]

[0496] The ordinary light refractive index of BBA(βN2)B-03 and mmtBuBioFBi was measured and the results are shown in Figure 24. The measurements were performed using a spectroscopic ellipsometer (M-2000U manufactured by J.A. Woollam Japan). The measurement samples used were films of approximately 50 nm thickness formed by vacuum deposition of the materials for each layer on a quartz substrate.

[0497] From the figure, it can be seen that BBA(βN2)B-03 and mmtBuBioFBi are a combination in which the difference is 0.2 or more and less than 0.5 in the range of 450 nm to 650 nm.

[0498] Furthermore, the HOMO levels of BBA(βN2)B-03 and mmtBuBioFBi calculated from the results of cyclic voltammetry (CV) measurements were -5.47 eV and -5.42 eV, respectively, when N,N-dimethylformamide (DMF) was used as the solvent. From this, it can be seen that the difference in the HOMO levels of BBA(βN2)B-03 and mmtBuBioFBi is 0.1 eV or less. 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.

[0499] The above light-emitting device and the comparative light-emitting device were sealed with a glass substrate in a glove box with a nitrogen atmosphere so that the light-emitting device was not exposed to the atmosphere (a UV-curable sealant was applied around the element, UV was irradiated only on the sealant without irradiating the light-emitting device, and heat-treated at 80°C under atmospheric pressure for 1 hour), and then the initial characteristics of these light-emitting devices were measured.

[0500] The luminance-current density characteristics of light-emitting device 10 and comparative light-emitting device 10 are shown in Fig. 25, luminance-voltage characteristics in Fig. 26, current efficiency-luminance characteristics in Fig. 27, current density-voltage characteristics in Fig. 28, blue index-luminance characteristics in Fig. 29, emission spectra in Fig. 30, and viewing angle characteristics in Fig. 31. ２ Table 5 shows the main characteristics around this angle. The luminance, CIE chromaticity, and emission spectrum were measured using a spectroradiometer (SR-UL1R, manufactured by Topcon Corporation) at room temperature. The viewing angle characteristics were measured by setting the direction perpendicular to the light-emitting surface of the light-emitting device at 0° and measuring the emission spectrum in 10° increments from -80° to 80° to obtain the photon intensity ratio of the light-emitting element at each angle. A multichannel spectrometer (PMA-12, manufactured by Hamamatsu Photonics) was used for the measurements.

[0501]

[0502] 25 to 31 and Table 5 show that light-emitting device 10 of one embodiment of the present invention is a light-emitting device with excellent current efficiency and blue index (BI). In particular, the BI is very high, at 200 (cd / A / y) or more, and light-emitting device 10 can be said to be a light-emitting device with particularly excellent BI. Therefore, one embodiment of the present invention is particularly suitable as a light-emitting device used in a display.

[0503] 31, there is almost no difference in the viewing angle characteristics between the light-emitting device 10 and the comparative light-emitting device 10. Therefore, according to one embodiment of the present invention, the efficiency of the light-emitting device can be increased without changing the viewing angle characteristics.

[0504] In addition, the current density is 50 mA / cm ２ 32 shows a graph showing the change in luminance with respect to the driving time in the case of the light-emitting device 10. It was found that the light-emitting device 10 according to one embodiment of the present invention was a light-emitting device with better reliability than the comparative light-emitting device 10.

[0505] In this example, a light-emitting device 20 which is a light-emitting device according to one embodiment of the present invention will be described. The structural formulae of organic compounds used in this example are shown below.

[0506]

[0507] (Method of Manufacturing the Light-Emitting Device 20) First, a silver (Ag) film was formed on a glass substrate by sputtering to a thickness of 100 nm as a reflective electrode, and then an indium tin oxide containing silicon oxide (ITSO) film was formed on a glass substrate by sputtering to a thickness of 10 nm as a transparent electrode, forming a first electrode 101. The electrode area was 4 mm ２ The first electrode 101 is a transparent electrode, and can be regarded as the first electrode together with the reflective electrode.

[0508] Next, as a pretreatment for forming a light-emitting device on the substrate, 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.

[0509] Then, 10 −４ The substrate was introduced into a vacuum deposition apparatus whose internal pressure had been reduced to about Pa, and was subjected to vacuum baking at 170° C. for 30 minutes in a heating chamber within the vacuum deposition apparatus, after which the substrate was allowed to cool for about 30 minutes.

[0510] Next, the substrate on which the first electrode 101 was formed was fixed to a substrate holder provided in a vacuum deposition apparatus so that the surface on which the first electrode 101 was formed faced downward. N-3′,5′-ditertiarybutyl-1,1′-biphenyl-4-yl-N-1,1′-biphenyl-2-yl-9,9,-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBuBioFBi) represented by the above structural formula (ix) and an electron acceptor material (OCHD-003) having a molecular weight of 672 and containing fluorine were co-deposited by a deposition method to a thickness of 10 nm on the first electrode 101 so as to give a weight ratio of 1:0.04 (=mmtBuBioFBi:OCHD-003), thereby forming a hole injection layer 111.

[0511] On the hole injection layer 111, a hole transport layer 112 was formed by depositing mmtBuBioFBi to a thickness of 35 nm as a first layer, 4,4′-diphenyl-4″-(7;2′-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B-03) represented by the above structural formula (x) to a thickness of 50 nm as a second layer, and mmtBuBioFBi to a thickness of 40 nm as a third layer.

[0512] Subsequently, N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP) represented by the above structural formula (xi) was vapor-deposited on the hole-transporting layer 112 to a thickness of 10 nm to form an electron-blocking layer.

[0513] Thereafter, 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: αN-βNPAnth) represented by the structural formula (xii) above and 2,12-di(tert-butyl)-5,9-di(4-tert-butylphenyl)-N,N-diphenyl-5H,9H-[1,4]benzazaborino[2,3,4-kl]phenazaborin-7-amine (abbreviation: DPhA-tBu4DABNA) represented by the structural formula (xiii) above were co-deposited to a thickness of 20 nm so as to give a weight ratio of 1:0.015 (=αN-βNPAnth:DPhA-tBu4DABNA), to form the light-emitting layer 113.

[0514] After that, 6-(1,1′-biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm) represented by the above structural formula (xiv) was evaporated to a thickness of 5 nm to form a hole blocking layer, and then 2,9-di(2-naphthyl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBPhen) represented by the above structural formula (xv) was evaporated to a thickness of 5 nm to form an electron transport layer 114.

[0515] After the formation of the electron transport layer 114, bathophenanthroline (abbreviation: BPhen) represented by the above structural formula (xvi) and lithium fluoride (LiF) were co-deposited to a thickness of 27 nm so as to give a volume ratio of 1:3 (=BPhen:LiF) to form the electron injection layer 115. Finally, silver (Ag) and magnesium (Mg) were co-deposited to give a volume ratio of 10:0.5 and a film thickness of 15 nm to form the second electrode 102 (second electrode), thereby producing the light-emitting device 20. Note that this is a semi-transmissive / semi-reflective electrode having the function of reflecting light and the function of transmitting light, and the light-emitting device of this example is a top-emission element in which light is extracted from the second electrode 102. In addition, 4,4′,4″-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) represented by the above structural formula (vii) is vapor-deposited on the second electrode 102 to a thickness of 70 nm to improve extraction efficiency.

[0516] The element structure of the light-emitting device 20 is summarized in the table below.

[0517]

[0518] The ordinary light refractive index of BBA(βN2)B-03 and mmtBuBioFBi was measured and the results are shown in Figure 24. The measurements were performed using a spectroscopic ellipsometer (M-2000U manufactured by J.A. Woollam Japan). The measurement samples used were films of approximately 50 nm thickness formed by vacuum deposition of the materials for each layer on a quartz substrate.

[0519] From the figure, it can be seen that BBA(βN2)B-03 and mmtBuBioFBi are a combination in which the difference is 0.2 or more and less than 0.5 in the range of 450 nm to 650 nm.

[0520] Furthermore, the HOMO levels of BBA(βN2)B-03 and mmtBuBioFBi calculated from the results of cyclic voltammetry (CV) measurements were -5.47 eV and -5.42 eV, respectively, when N,N-dimethylformamide (DMF) was used as the solvent. From this, it can be seen that the difference in the HOMO levels of BBA(βN2)B-03 and mmtBuBioFBi is 0.1 eV or less. 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.

[0521] The above light-emitting device and the comparative light-emitting device were sealed with a glass substrate in a glove box with a nitrogen atmosphere so that the light-emitting device was not exposed to the atmosphere (a UV-curable sealant was applied around the element, UV was irradiated only on the sealant without irradiating the light-emitting device, and heat-treated at 80°C under atmospheric pressure for 1 hour), and then the initial characteristics of these light-emitting devices were measured.

[0522] The luminance-current density characteristics of the light-emitting device 1 and the comparative light-emitting device 10 are shown in FIG. 33, the luminance-voltage characteristics in FIG. 34, the current efficiency-luminance characteristics in FIG. 35, the current density-voltage characteristics in FIG. 36, the blue index-luminance characteristics in FIG. 37, and the emission spectrum in FIG. 38. ２ The main characteristics in the vicinity are shown in Table 7. The luminance, CIE chromaticity, and emission spectrum were measured using a spectroradiometer (SR-UL1R, manufactured by Topcon Corporation) at room temperature.

[0523]

[0524] 33 to 38 and Table 7 show that light-emitting device 20 of one embodiment of the present invention is a light-emitting device that exhibits very good current efficiency and blue index (BI). In particular, the BI is very high, at 250 (cd / A / y) or more, and light-emitting device 20 can be said to be a light-emitting device with particularly good BI. Therefore, one embodiment of the present invention is particularly suitable as a light-emitting device used in a display.

[0525] In addition, the current density is 50 mA / cm ２A graph showing the change in luminance with respect to the driving time in the case of the light-emitting device 20 according to one embodiment of the present invention was found to be a highly reliable light-emitting device.

[0526] In this example, a light-emitting device 30 which is a light-emitting device according to one embodiment of the present invention will be described. The structural formulas of organic compounds used in this example are shown below.

[0527]

[0528] (Method of Manufacturing the Light-Emitting Device 30) First, a silver (Ag) film was formed on a glass substrate by sputtering to a thickness of 100 nm as a reflective electrode, and then an indium tin oxide containing silicon oxide (ITSO) film was formed by sputtering to a thickness of 5 nm as a transparent electrode to form a first electrode 101. The electrode area was 4 mm ２ The first electrode 101 is a transparent electrode, and can be regarded as the first electrode together with the reflective electrode.

[0529] Next, as a pretreatment for forming a light-emitting device on the substrate, 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.

[0530] Then, 10 −４ The substrate was introduced into a vacuum deposition apparatus whose internal pressure had been reduced to about Pa, and was subjected to vacuum baking at 170° C. for 30 minutes in a heating chamber within the vacuum deposition apparatus, after which the substrate was allowed to cool for about 30 minutes.

[0531] Next, the substrate on which the first electrode 101 was formed was fixed to a substrate holder provided in a vacuum deposition apparatus so that the surface on which the first electrode 101 was formed faced downward. N-3′,5′-ditertiarybutyl-1,1′-biphenyl-4-yl-N-1,1′-biphenyl-2-yl-9,9,-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBuBioFBi) represented by the above structural formula (ix) and an electron acceptor material (OCHD-003) having a molecular weight of 672 and containing fluorine were co-deposited by a deposition method to a thickness of 10 nm on the first electrode 101 so as to give a weight ratio of 1:0.1 (=mmtBuBioFBi:OCHD-003), thereby forming a hole injection layer 111.

[0532] On the hole injection layer 111, a hole transport layer 112 was formed by depositing mmtBuBioFBi to a thickness of 42.5 nm as a first layer, 4,4′-diphenyl-4″-(7;2′-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B-03) represented by the above structural formula (x) to a thickness of 50 nm as a second layer, and mmtBuBioFBi to a thickness of 40 nm as a third layer.

[0533] Subsequently, N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP) represented by the above structural formula (xi) was vapor-deposited on the hole-transporting layer 112 to a thickness of 10 nm to form an electron-blocking layer.

[0534] Thereafter, 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: αN-βNPAnth) represented by the structural formula (xii) above and 3,10-bis[N-(9-phenyl-9H-carbazol-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b′]bisbenzofuran (abbreviation: 3,10PCA2Nbf(IV)-02) represented by the structural formula (iii) above were co-deposited to a thickness of 20 nm so as to give a weight ratio of 1:0.015 (=αN-βNPAnth:3,10PCA2Nbf(IV)-02), to form a light-emitting layer 113.

[0535] Thereafter, 6-(1,1′-biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm) represented by the structural formula (xiv) above was deposited to a thickness of 10 nm to form a hole blocking layer, and then 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn) represented by the structural formula (v) above and 8-hydroxyquinolinatolithium (abbreviation: Liq) represented by the structural formula (vi) above were co-deposited to a thickness of 20 nm in a weight ratio of 0.4:0.6 (=mPn-mDMePyPTzn:Liq) to form an electron transport layer 114.

[0536] After forming the electron transport layer 114, lithium fluoride (LiF) was deposited to a thickness of 1 nm to form the electron injection layer 115. Finally, silver (Ag) and magnesium (Mg) were co-deposited at a volume ratio of 1:0.1 to form a 15 nm film thickness to form the second electrode 102 (second electrode), thereby producing the light-emitting device 10. The second electrode 102 is a semi-transparent / semi-reflective electrode that has the functions of reflecting and transmitting light, and the light-emitting device of this example is a top-emission element that extracts light from the second electrode 102. A 65 nm thick organic compound was also deposited on the second electrode 102 as a cap layer to improve extraction efficiency.

[0537] The element structure of the light-emitting device 30 is summarized in the table below.

[0538]

[0539] The ordinary light refractive index of BBA(βN2)B-03 and mmtBuBioFBi was measured and the results are shown in Figure 24. The measurements were performed using a spectroscopic ellipsometer (M-2000U manufactured by J.A. Woollam Japan). The measurement samples used were films of approximately 50 nm thickness formed by vacuum deposition of the materials for each layer on a quartz substrate.

[0540] From the figure, it can be seen that BBA(βN2)B-03 and mmtBuBioFBi are a combination in which the difference is 0.2 or more and less than 0.5 in the range of 450 nm to 650 nm.

[0541] Furthermore, the HOMO levels of BBA(βN2)B-03 and mmtBuBioFBi calculated from the results of cyclic voltammetry (CV) measurements were -5.47 eV and -5.42 eV, respectively, when N,N-dimethylformamide (DMF) was used as the solvent. From this, it can be seen that the difference in the HOMO levels of BBA(βN2)B-03 and mmtBuBioFBi is 0.1 eV or less. 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.

[0542] The above light-emitting device and the comparative light-emitting device were sealed with a glass substrate in a glove box with a nitrogen atmosphere so that the light-emitting device was not exposed to the atmosphere (a UV-curable sealant was applied around the element, UV was irradiated only on the sealant without irradiating the light-emitting device, and heat-treated at 80°C under atmospheric pressure for 1 hour), and then the initial characteristics of these light-emitting devices were measured.

[0543] The luminance-current density characteristics of the light-emitting device 30 are shown in Fig. 40, the luminance-voltage characteristics in Fig. 41, the current efficiency-luminance characteristics in Fig. 42, the current density-voltage characteristics in Fig. 43, the blue index-luminance characteristics in Fig. 44, and the emission spectrum in Fig. 45. ２ The main characteristics in the vicinity are shown in Table 9. The luminance, CIE chromaticity, and emission spectrum were measured using a spectroradiometer (SR-UL1R, manufactured by Topcon Corporation) at room temperature.

[0544]

[0545] 40 to 45 and Table 9 show that light-emitting device 30 of one embodiment of the present invention is a light-emitting device with excellent current efficiency and blue index (BI). In particular, the BI is very high, at 200 (cd / A / y) or more, and light-emitting device 30 can be said to be a light-emitting device with particularly excellent BI. Therefore, one embodiment of the present invention is particularly suitable as a light-emitting device used in a display.

[0546] In addition, the current density is 50 mA / cm ２ 46 shows a graph showing the change in luminance with respect to the driving time in the light-emitting device 30. It was found that the light-emitting device 30 according to one embodiment of the present invention has high reliability.

[0547] In this example, light-emitting devices 40 and 41 are described, each having a different order of GSP values ​​in the first hole transport layer, the second hole transport layer, and the third hole transport layer. The structural formulas of the organic compounds used in this example are shown below.

[0548]

[0549] (Method of Manufacturing the Light-Emitting Device 40) First, a silver (Ag) film was formed on a glass substrate by sputtering to a thickness of 100 nm as a reflective electrode, and then an indium tin oxide containing silicon oxide (ITSO) film was formed on a glass substrate by sputtering to a thickness of 5 nm as a transparent electrode, forming a first electrode 101. The electrode area was 4 mm ２ The first electrode 101 is a transparent electrode, and can be regarded as the first electrode together with the reflective electrode.

[0550] Next, as a pretreatment for forming a light-emitting device on the substrate, 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.

[0551] Then, 10 −４ The substrate was introduced into a vacuum deposition apparatus whose internal pressure had been reduced to about Pa, and was subjected to vacuum baking at 170° C. for 30 minutes in a heating chamber within the vacuum deposition apparatus, after which the substrate was allowed to cool for about 30 minutes.

[0552] Next, the substrate on which the first electrode 101 was formed was fixed to a substrate holder provided in a vacuum deposition apparatus so that the surface on which the first electrode 101 was formed faced downward. N-3′,5′-ditertiarybutyl-1,1′-biphenyl-4-yl-N-1,1′-biphenyl-2-yl-9,9,-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBuBioFBi) represented by the above structural formula (ix) and an electron acceptor material (OCHD-003) having a molecular weight of 672 and containing fluorine were co-deposited by a deposition method to a thickness of 10 nm on the first electrode 101 so as to give a weight ratio of 1:0.1 (=mmtBuBioFBi:OCHD-003), thereby forming a hole injection layer 111.

[0553] On the hole injection layer 111, a hole transport layer 112 was formed by depositing mmtBuBioFBi to a thickness of 40 nm as a first layer, 4,4′-diphenyl-4″-(7;2′-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B-03) represented by the above structural formula (x) to a thickness of 50 nm as a second layer, and mmtBuBioFBi to a thickness of 40 nm as a third layer.

[0554] Subsequently, N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP) represented by the above structural formula (xi) was vapor-deposited on the hole-transporting layer 112 to a thickness of 10 nm to form an electron-blocking layer.

[0555] Thereafter, 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: αN-βNPAnth) represented by the structural formula (xii) above and 3,10-bis[N-(9-phenyl-9H-carbazol-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b′]bisbenzofuran (abbreviation: 3,10PCA2Nbf(IV)-02) represented by the structural formula (iii) above were co-deposited to a thickness of 20 nm so as to give a weight ratio of 1:0.015 (=αN-βNPAnth:3,10PCA2Nbf(IV)-02), to form a light-emitting layer 113.

[0556] Thereafter, 6-(1,1′-biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm) represented by the structural formula (xiv) above was evaporated to a thickness of 10 nm to form a hole blocking layer, and then 2-{(3′,5′-di-tert-butyl)-1,1′-biphenyl-3-yl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mmtBumBPTzn) represented by the structural formula (xix) above and 6-methyl-8-quinolinolato-lithium (abbreviation: Li-6mq) represented by the structural formula (xx) above were co-evaporated to a thickness of 20 nm to give a weight ratio of 1:1 (=mmtBumBPTzn:Li-6mq) to form an electron transport layer 114.

[0557] After forming the electron transport layer 114, lithium fluoride (LiF) was deposited to a thickness of 1 nm to form the electron injection layer 115. Finally, silver (Ag) and magnesium (Mg) were co-evaporated to a volume ratio of 1:0.1 and a film thickness of 15 nm to form the second electrode 102, thereby producing the light-emitting device 10. The second electrode is a semi-transparent / semi-reflective electrode that has the functions of reflecting and transmitting light, and the light-emitting device of this example is a top-emission element that extracts light from the second electrode 102. In addition, a cap layer made of an organic compound was evaporated to a thickness of 65 nm on the second electrode 102 to improve extraction efficiency.

[0558] (Method of Fabricating Light-Emitting Device 41) Light-emitting device 41 was fabricated in the same manner as light-emitting device 40, except that mmtBuBioFBi in the hole injection layer 111 and the first layer of the hole transport layer 112 of light-emitting device 40 was replaced with N-(3″,5′,5″-tri-tert-butyl-1,1′:3′,1″-terphenyl-4-yl)-N-(1,1′-biphenyl-2-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPoFBi-04) represented by the above structural formula (xviii), and the first layer of the hole transport layer 112 was formed to a thickness of 52.5 nm.

[0559] (Method of Fabricating Comparative Light-Emitting Device 40) Comparative light-emitting device 40 was fabricated in the same manner as light-emitting device 40 or light-emitting device 41, except that hole transport layer 112 was formed by depositing mmtBuBioFBi to a thickness of 130 nm.

[0560] The device structures of light-emitting device 40, light-emitting device 41 and comparative light-emitting device 40 are summarized in the table below.

[0561]

[0562]

[0563] The ordinary refractive indexes of mmtBuBioFBi, BBA(βN2)B-03, and mmtBumTPoFBi-04 were measured and the results are shown in Figures 47A and 47B. The measurements were performed using a spectroscopic ellipsometer (M-2000U, manufactured by J.A. Woollam Japan). The measurement samples used were films of approximately 50 nm thickness formed by vacuum deposition of the materials for each layer on a quartz substrate.

[0564] From the figure, it can be seen that BBA(βN2)B-03 and mmtBuBioFBi, and BBA(βN2)B-03 and mmtBumTPoFBi-04 are combinations in which the difference in refractive index is 0.2 or more and less than 0.5 in the range of 450 nm to 650 nm.

[0565] The HOMO levels of BBA(βN2)B-03, mmtBuBioFBi, and mmtBumTPoFBi-04 calculated from the results of cyclic voltammetry (CV) measurements were -5.47 eV, -5.42 eV, and -5.42 eV, respectively, when N,N-dimethylformamide (DMF) was used as the solvent. From this, the difference in the HOMO levels between BBA(βN2)B-03 and mmtBuBioFBi, and the difference in the HOMO levels between BBA(βN2)B-03 and mmtBumTPoFBi-04, were each 0.1 eV or less. The CV measurement was performed using an electrochemical analyzer (manufactured by BAS Co., Ltd., model number: ALS Model 600A or 600C) to measure a solution in which the material to be measured was dissolved in a solvent.

[0566] The GSPs of mmtBuBioFBi, BBA(βN2)B-03, and mmtBumTPoFBi-04 are shown in the table below. From the table, it can be seen that light-emitting device 40 is a device fabricated without considering GSP, while light-emitting device 41 is a light-emitting device fabricated with GSP taken into consideration, in which the GSP of the third layer is the largest and the value obtained by subtracting the GSP of the second layer from the GSP of the first layer is 10 mV / nm or less.

[0567]

[0568] The above light-emitting devices were sealed with glass substrates in a glove box with a nitrogen atmosphere to prevent the light-emitting devices from being exposed to the atmosphere (a UV-curable sealant was applied around the elements, UV was irradiated only onto the sealant without irradiating the light-emitting devices, and heat-treated at 80°C under atmospheric pressure for 1 hour).The initial characteristics of these light-emitting devices were then measured.

[0569] The luminance-current density characteristics of light-emitting device 40, light-emitting device 41, and comparative light-emitting device 40 are shown in Figure 48, luminance-voltage characteristics in Figure 49, current efficiency-luminance characteristics in Figure 50, current density-voltage characteristics in Figure 51, blue index-luminance characteristics in Figure 52, power efficiency-luminance characteristics in Figure 53, and emission spectra in Figure 54. The 1000 cd / m ２ The main characteristics around 10 ...

[0570]

[0571] 48 to 54 and Table 13 show that light-emitting device 40, light-emitting device 41, and comparative light-emitting device 40 according to one embodiment of the present invention are all light-emitting devices with favorable characteristics. In particular, light-emitting device 40 and light-emitting device 41 having the configuration of the present invention have favorable current efficiency and BI because the hole-transport layer is composed of the first to third layers.

[0572] Comparing light-emitting device 40 with comparative light-emitting device 40, it can be seen that the driving voltage of light-emitting device 40 is higher due to the influence of interface resistance and the like resulting from the three-layer structure of hole transport layer 112. However, because the structure has a significant effect of improving current efficiency, the power efficiency of light-emitting device 40 exceeds that of the comparative light-emitting device even though the driving voltage is higher.

[0573] On the other hand, the light-emitting device 41, in which the first to third layers were formed in consideration of the GSP, exhibited a low driving voltage despite the hole transport layer 112 having a three-layer structure, and exhibited a lower value than the comparative light-emitting device 40, which had a single hole transport layer. As a result, it was found that the light-emitting device 41 was a light-emitting device that exhibited very good power efficiency.

[0574] In addition, the current density is 50 mA / cm ２ 55 shows a graph showing the change in luminance with respect to the driving time in the case of the light-emitting device 40. It was found that the light-emitting device 40 and the light-emitting device 41 according to one embodiment of the present invention are light-emitting devices with higher reliability than the comparative light-emitting device 40.

[0575] In this example, light-emitting devices 50 and 51 are described, each having a different order of GSP values ​​in the first hole transport layer, the second hole transport layer, and the third hole transport layer. The structural formulas of the organic compounds used in this example are shown below.

[0576]

[0577] (Method of Manufacturing the Light-Emitting Device 50) First, a silver (Ag) film was formed on a glass substrate by sputtering to a thickness of 100 nm as a reflective electrode, and then an indium tin oxide containing silicon oxide (ITSO) film was formed on a glass substrate by sputtering to a thickness of 10 nm as a transparent electrode, forming a first electrode 101. The electrode area was 4 mm ２ The first electrode 101 is a transparent electrode, and can be regarded as the first electrode together with the reflective electrode.

[0578] Next, as a pretreatment for forming a light-emitting device on the substrate, 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.

[0579] Then, 10 −４ The substrate was introduced into a vacuum deposition apparatus whose internal pressure had been reduced to about Pa, and was subjected to vacuum baking at 170° C. for 30 minutes in a heating chamber within the vacuum deposition apparatus, after which the substrate was allowed to cool for about 30 minutes.

[0580] Next, the substrate on which the first electrode 101 was formed was fixed to a substrate holder provided in a vacuum deposition apparatus so that the surface on which the first electrode 101 was formed faced downward. N-(3",5',5"-tri-tert-butyl-1,1':3',1"-terphenyl-4-yl)-N-(1,1'-biphenyl-2-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPoFBi-04) represented by the above structural formula (xviii) and an electron acceptor material (OCHD-003) having a molecular weight of 672 and containing fluorine were co-deposited by a deposition method to a thickness of 10 nm on the first electrode 101 so as to give a weight ratio of 1:0.1 (=mmtBumTPoFBi-04:OCHD-003), thereby forming a hole-injection layer 111.

[0581] A hole-transporting layer 112 was formed on the hole-injection layer 111 by depositing mmtBumTPoFBi-04 to a thickness of 50 nm as a first layer, 4-(dibenzothiophen-4-yl)-4′-phenyl-4″-(9-phenyl-9H-carbazol-2-yl)triphenylamine (abbreviation: PCBBiPDBt-02) represented by the above structural formula (xxi) to a thickness of 50 nm as a second layer, and N-(3′,5′,-di-tert-butyl-1,1′-biphenyl-4-yl)-bis(9,9-dimethyl-9H-fluorene)-2,2′-amine (abbreviation: mmtBuBiFF) represented by the above structural formula (xxii) to a thickness of 50 nm as a third layer.

[0582] Thereafter, 11-(4-[1,1′-biphenyl]-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) represented by the structural formula (xxiii) above, 9-(2-naphthyl)-9′-phenyl-9H,9′H-3,3′-bicarbazole (abbreviation: βNCCP) represented by the structural formula (xxiv) above, and [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)) in a weight ratio of 0.5:0.5:0.1 (=BP-Icz(II)Tzn:βNCCP:Ir(ppy) ２ (mbfpypy-d3)) was co-evaporated to a thickness of 40 nm to form the light-emitting layer 113.

[0583] Thereafter, 2-[3′-(9,9-dimethyl-9H-fluoren-2-yl)-1,1′-biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn) represented by the structural formula (iv) above was deposited to a thickness of 10 nm to form a hole blocking layer, and 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn) represented by the structural formula (v) above and 8-hydroxyquinolinato-lithium (abbreviation: Liq) represented by the structural formula (vi) above were co-deposited to a thickness of 25 nm in a weight ratio of 1:1 (=mPn-mDMePyPTzn:Liq) to form an electron transport layer 114.

[0584] After forming the electron transport layer 114, lithium fluoride (LiF) was deposited to a thickness of 1 nm to form the electron injection layer 115. Finally, silver (Ag) and magnesium (Mg) were co-deposited at a volume ratio of 1:0.1 and a film thickness of 15 nm to form the second electrode 102, thereby producing the light-emitting device 10. The second electrode was a semi-transparent / semi-reflective electrode having the functions of reflecting and transmitting light, and the light-emitting device of this example was a top-emission element in which light was extracted from the second electrode 102. In addition, 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) represented by the above structural formula (vii) was deposited to a thickness of 70 nm on the second electrode 102 to improve extraction efficiency.

[0585] (Method of Fabricating Comparative Light-Emitting Device 50) Light-emitting device 51 was fabricated in the same manner as light-emitting device 50, except that mmtBumTPoFBi-04 and PCBBiPDBt-02 were swapped.

[0586] The device structures of the light-emitting device 50 and the comparative light-emitting device 50 are summarized in the table below.

[0587]

[0588] The ordinary refractive index of mmtBumTPoFBi-04, PCBBiPDBt-02, and mmtBuBiFF was measured and the results are shown in Figures 62A and 62B. The measurements were performed using a spectroscopic ellipsometer (M-2000U, manufactured by J.A. Woollam Japan). The measurement samples used were films of approximately 50 nm thickness formed by vacuum deposition of the materials for each layer on a quartz substrate.

[0589] The figure shows that the light-emitting device 50 has a three-layer hole transport layer in which the second layer has a high refractive index and the first and third layers have low refractive indices. On the other hand, the comparative light-emitting device 50 has a three-layer hole transport layer in which the first layer has a high refractive index and the second and third layers have low refractive indices.

[0590] The HOMO levels of mmtBumTPoFBi-04, PCBBiPDBt-02, and mmtBuBiFF calculated from the results of cyclic voltammetry (CV) measurements were −5.42 eV, −5.48 eV, and −5.33 eV, respectively, when N,N-dimethylformamide (DMF) was used as the solvent. From this, the difference in the HOMO levels between mmtBumTPoFBi-04 and PCBBiPDBt-02, the difference in the HOMO levels between PCBBiPDBt-02 and mmtBuBiFF, and the difference in the HOMO levels between mmtBumTPoFBi-04 and mmtBuBiFF were each 0.2 eV or less. The CV measurement was performed using an electrochemical analyzer (manufactured by BAS Inc., model number: ALS model 600A or 600C) and a solution in which the material to be measured was dissolved in a solvent.

[0591] The GSPs of mmtBumTPoFBi-04, PCBBiPDBt-02, and mmtBuBiFF are shown in the table below. From the table below, it can be seen that light-emitting device 50 is a light-emitting device that was fabricated with GSP taken into consideration, with the third layer having the largest GSP and the first layer having the smallest GSP. On the other hand, comparative light-emitting device 50 is a light-emitting device in which the third layer has the largest GSP, but the value obtained by subtracting the second layer GSP from the first layer GSP is 10 or more.

[0592]

[0593] The above light-emitting devices were sealed with glass substrates in a glove box with a nitrogen atmosphere to prevent the light-emitting devices from being exposed to the atmosphere (a UV-curable sealant was applied around the elements, UV was irradiated only onto the sealant without irradiating the light-emitting devices, and heat-treated at 80°C under atmospheric pressure for 1 hour).The initial characteristics of these light-emitting devices were then measured.

[0594] The luminance-current density characteristics of the light-emitting device 50 and the comparative light-emitting device 50 are shown in Figure 56, the luminance-voltage characteristics in Figure 57, the current efficiency-luminance characteristics in Figure 58, the current density-voltage characteristics in Figure 59, the power efficiency-luminanc...

Claims

1. A light-emitting device including a first light-emitting device and a first color conversion layer, wherein the first light-emitting device includes a first electrode, a second electrode, a light-emitting layer positioned between the first electrode and the second electrode, a first layer, a second layer, and a third layer, the first layer is positioned between the first electrode and the second layer, the second layer is positioned between the first layer and the third layer, the third layer is positioned between the second layer and the light-emitting layer, the first layer contains a first organic compound, the second layer contains a second organic compound, the third layer contains a third organic compound, the ordinary light refractive index of the second organic compound at any wavelength between 450 nm and 650 nm is higher than the ordinary light refractive index of the first organic compound and the ordinary light refractive index of the third organic compound at the same wavelength, the first color conversion layer contains a first substance that absorbs light and emits light, and the first color conversion layer is positioned on an optical path through which light emitted by the first light-emitting device is emitted to the outside of the light-emitting device.

2. A light-emitting device including a first light-emitting device and a first color conversion layer, wherein the first light-emitting device includes a first electrode, a second electrode, a light-emitting layer positioned between the first electrode and the second electrode, a first layer, a second layer, and a third layer, the first layer is positioned between the first electrode and the second layer, the second layer is positioned between the first layer and the third layer, the third layer is positioned between the second layer and the light-emitting layer, the light-emitting layer contains a light-emitting material that emits light having a peak wavelength of wavelength λ, the first layer contains a first organic compound, the second layer contains a second organic compound, the third layer contains a third organic compound, the ordinary light refractive index of the second organic compound at the wavelength λ is higher than the ordinary light refractive index of the first organic compound and the ordinary light refractive index of the third organic compound at the wavelength λ, the first color conversion layer contains a first substance that absorbs light and emits light, and the first color conversion layer is positioned on an optical path through which light emitted by the first light-emitting device is emitted to the outside of the light-emitting device.

3. The light-emitting device according to claim 1 or claim 2, wherein a difference between a HOMO level of the first organic compound and a HOMO level of the second organic compound is 0.2 eV or less.

4. In claim 1 or 2, The light emitting device, wherein the first layer, the second layer, and the third layer each have a thickness of 25 nm or more and 70 nm or less.

5. In claim 1 or 2, a difference between the ordinary refractive index of the second organic compound at the wavelength λ and the ordinary refractive index of the first organic compound at the wavelength λ, and a difference between the ordinary refractive index of the second organic compound at the wavelength λ and the ordinary refractive index of the third organic compound at the wavelength λ, each being 0.2 or more and less than 0.

5.

6. In claim 1 or 2, A light emitting device, wherein a value obtained by subtracting the GSP (mV / nm) of the second organic compound from the GSP (mV / nm) of the third organic compound is −10 (mV / nm) or more.

7. In claim 1 or 2, A light emitting device, wherein a value obtained by subtracting the GSP (mV / nm) of the first organic compound from the GSP (mV / nm) of the second organic compound is −10 (mV / nm) or more.

8. In claim 1 or 2, A light emitting device, wherein the first color conversion layer has a refractive index of 1.40 or more and 2.10 or less for light with a wavelength of 455 nm or more and 465 nm or less.

9. In claim 1 or 2, a first layer including a fourth organic compound between the first light-emitting device and the first color conversion layer; A light emitting device, wherein the first layer has a refractive index of 1.40 or more and 2.10 or less for light having a wavelength of 455 nm or more and 465 nm or less.

10. In claim 1 or 2, The light emitting device, wherein the first material is a quantum dot.

11. In claim 1 or 2, the light emitting device further includes a second light emitting device, a third light emitting device, and a second color conversion layer; the second light emitting device and the third light emitting device have a similar structure to the first light emitting device; the second color conversion layer has a second substance that absorbs light and emits light; a peak wavelength of an emission spectrum of the first substance is different from a peak wavelength of an emission spectrum of the second substance; a light emitting device, the second color conversion layer being located on an optical path along which light emitted from the second light emitting device exits the light emitting device;

12. In claim 11, The light emitting device, wherein the second material is a quantum dot.

13. A display device comprising the light emitting device according to claim 1 or 2.

14. 3. An electronic device comprising the light emitting device according to claim 1.

15. A lighting device comprising the light-emitting device according to claim 1 or claim 2.