Material for hole-transporting layer, material for electron-transporting layer, light-emitting device, and electronic device

Abstract

To provide an organic semiconductor device with a low driving voltage.SOLUTION: A light emitting device including a material for a transport layer in the light-emitting device includes an anode, a cathode, and an EL layer positioned between the anode and the cathode, the EL layer includes a hole transport layer and a light emitting layer, the hole transport layer is located between the anode and the light emitting layer, the hole transport layer and the anode are not in contact, and the hole transport layer has a surface potential gradient GSP_slope (mV / nm) of a deposition film of 20 (mV / nm) or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One aspect of the present invention relates to organic compounds, organic semiconductor devices, light-emitting devices, light-emitting devices, organic EL devices, photodiode sensors, display modules, lighting modules, display devices, light-emitting devices, electronic devices, lighting devices, and electronic devices. However, one aspect of the present invention is not limited to the above-mentioned technical fields. The technical fields of one aspect of the invention disclosed herein relate to products, methods, or methods of manufacturing. Alternatively, one aspect of the present invention relates to processes, machines, manufacturers, or compositions of matter. More specifically, examples of the technical fields of one aspect of the present invention disclosed herein include semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, lighting devices, energy storage devices, memory devices, imaging devices, methods for driving them, or methods for manufacturing them. [Background technology]

[0002] The practical application of light-emitting devices (organic EL devices) that utilize electroluminescence (EL) using organic compounds is progressing. The basic structure of these light-emitting devices is an organic compound layer (EL layer) containing a light-emitting material sandwiched between a pair of electrodes. By applying a voltage to this device, carriers are injected, and by utilizing the recombination energy of these carriers, light emission can be obtained from the light-emitting material.

[0003] Because these light-emitting devices are self-emissive, using them as pixels in a display offers advantages over liquid crystal displays, such as higher visibility and the elimination of the need for a backlight, making them particularly suitable for flat-panel displays. Another major advantage of displays using such light-emitting devices is that they can be manufactured to be thin and lightweight. Furthermore, they are characterized by their extremely fast response speed.

[0004] Furthermore, since these light-emitting devices can form a continuous, planar light-emitting layer, they can produce light in a planar manner. This is a feature that is difficult to obtain with point light sources such as incandescent bulbs and LEDs, or line light sources such as fluorescent lamps, and therefore has high value as a surface light source that can be applied to lighting and other applications.

[0005] As described above, displays and lighting devices using light-emitting devices are suitable for various electronic devices, but research and development are underway to find light-emitting devices with even better characteristics (see, for example, Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] Hiroshi Noguchi, et al., "Orientational Polarization Phenomena of Polar Molecules and Interface Properties of Organic Thin Film Devices," Journal of the Vacuum Society of Japan, 2015, Vol. 58, No. 3. [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] One aspect of the present invention aims to provide any of the transport layer material, hole transport layer material, electron transport layer material, electron block layer material, or hole block layer material that can provide an organic semiconductor device with a low driving voltage. Alternatively, one aspect of the present invention aims to provide any of the transport layer material, hole transport layer material, electron transport layer material, electron block layer material, or hole block layer material that can provide a light-emitting device with a low driving voltage. Alternatively, one aspect of the present invention aims to provide any of the transport layer material, hole transport layer material, electron transport layer material, electron block layer material, or hole block layer material that can provide a photodiode sensor with a low driving voltage. Alternatively, one aspect of the present invention aims to provide any of the transport layer material, hole transport layer material, electron transport layer material, electron block layer material, or hole block layer material that can provide a light-emitting device, electronic device, display device, or electronic device with low power consumption.

[0008] Furthermore, one aspect of the present invention aims to provide an organic semiconductor device with a low driving voltage. Alternatively, one aspect of the present invention aims to provide a light-emitting device with a low driving voltage. Alternatively, one aspect of the present invention aims to provide a photodiode sensor with a low driving voltage. Alternatively, one aspect of the present invention aims to provide any of the following: a light-emitting device, electronic device, display device, or electronic device with low power consumption.

[0009] The present invention only needs to solve one of the above-mentioned problems. [Means for solving the problem]

[0010] One aspect of the present invention is a material for a hole transport layer in a light-emitting device, wherein the potential gradient GSP_slope(mV / nm) of the surface potential of the deposited film is 20(mV / nm) or more.

[0011] Alternatively, another aspect of the present invention is a hole transport layer material for a light-emitting device in which the GSP_slope is 100 (mV / nm) or less.

[0012] Alternatively, one aspect of the present invention is a hole transport layer material for a light-emitting device, wherein, in the above configuration, the material has a paraphotonic refractive index of 1.50 or more and 1.75 or less for light with a wavelength of 450 nm.

[0013] Alternatively, another aspect of the present invention is a hole transport layer material for a light-emitting device, wherein, in the above configuration, the material has a paraphotonic refractive index of 1.45 or more and 1.70 or less for light with a wavelength of 633 nm.

[0014] Alternatively, another aspect of the present invention is a hole transport layer material for a light-emitting device, wherein the glass transition temperature Tg(°C) of the material is 100°C or higher.

[0015] Alternatively, another aspect of the present invention is a hole transport layer material for a light-emitting device having at least three groups selected from chain alkyl groups having 2 to 5 carbon atoms or cycloalkyl groups having 6 to 12 carbon atoms, in the above configuration.

[0016] Alternatively, another aspect of the present invention is a material for a hole transport layer in a light-emitting device, wherein the alkyl group is a branched chain alkyl group having 3 to 5 carbon atoms in the above configuration.

[0017] Alternatively, another aspect of the present invention is a material for a hole transport layer in a light-emitting device, wherein the alkyl group in the above configuration is a t-butyl group.

[0018] Alternatively, another aspect of the present invention is a hole transport layer material for a light-emitting device, wherein, in the above configuration, the proportion of carbon atoms forming bonds with sp3 hybrid orbitals relative to the total number of carbon atoms in the molecule is 23% or more and 55% or less.

[0019] Alternatively, in another aspect of the present invention, 1 This material, measured by 1H-NMR, is suitable for hole transport layers in light-emitting devices because the integrated signal value below 4 ppm exceeds the integrated signal value above 4 ppm.

[0020] Alternatively, in another aspect of the present invention, the material is a hole transport layer material for a light-emitting device having hole transport properties, in the above configuration.

[0021] Alternatively, another aspect of the present invention is a material for a hole transport layer in a light-emitting device, wherein the material is an arylamine in the above configuration.

[0022] Alternatively, another aspect of the present invention is a material for a hole transport layer in a light-emitting device, wherein, in the above configuration, the material has condensed aromatic hydrocarbon rings, the condensed aromatic hydrocarbon rings are condensed rings of three or fewer rings, and the total number of condensed aromatic hydrocarbon rings in the material molecule is one or two.

[0023] Alternatively, another aspect of the present invention is a hole transport layer material for a light-emitting device, wherein, in the above configuration, the material has two or fewer intramolecular fluorene skeletons.

[0024] Alternatively, another aspect of the present invention is an electron blocking layer material comprising the above-described hole transport layer material.

[0025] Alternatively, another aspect of the present invention is a material for an electron transport layer in a light-emitting device, wherein the potential gradient GSP_slope(mV / nm) of the surface potential of the deposited film is 20(mV / nm) or more, and the ordinary refractive index for light with a wavelength of 450 nm is 1.50 or more and 1.75 or less.

[0026] Alternatively, another aspect of the present invention is a material for an electron transport layer in a light-emitting device, wherein the potential gradient GSP_slope(mV / nm) of the surface potential of the deposited film is 20(mV / nm) or more, and the ordinary refractive index for light with a wavelength of 633nm is 1.45 or more and 1.70 or less.

[0027] Alternatively, another aspect of the present invention is a material for the electron transport layer of a light-emitting device, wherein the GSP_slope is 100 (mV / nm) or less in the above configuration.

[0028] Alternatively, another aspect of the present invention is a material for an electron transport layer of a light-emitting device, wherein the glass transition temperature Tg(°C) of the material is 100°C or higher, in the above configuration.

[0029] Alternatively, another aspect of the present invention is a material for an electron transport layer of a light-emitting device having at least three groups selected from chain alkyl groups having 2 to 5 carbon atoms or cycloalkyl groups having 6 to 12 carbon atoms, in the above configuration.

[0030] Alternatively, another aspect of the present invention is a material for an electron transport layer of a light-emitting device in which, in the above configuration, the alkyl group is a branched chain alkyl group having 3 to 5 carbon atoms.

[0031] Alternatively, another aspect of the present invention is a material for an electron transport layer of a light-emitting device, wherein the alkyl group in the above configuration is a t-butyl group.

[0032] Alternatively, another aspect of the present invention is a material for an electron transport layer of a light-emitting device in which, in the above configuration, the proportion of carbon atoms forming bonds with sp3 hybrid orbitals relative to the total number of carbon atoms in the molecule is 23% or more and 55% or less.

[0033] Alternatively, in another aspect of the present invention, 1 This material, measured by 1H-NMR, is suitable for electron transport layers in light-emitting devices, as the integrated signal value below 4 ppm exceeds the integrated signal value above 4 ppm.

[0034] Alternatively, in another aspect of the present invention, the material is a material for an electron transport layer of a light-emitting device having electron transport properties, in the above configuration.

[0035] Alternatively, another aspect of the present invention is a hole block layer material comprising the above-mentioned electron transport layer material.

[0036] Alternatively, another aspect of the present invention is a light-emitting device having an anode, a cathode, and an EL layer located between the anode and the cathode, wherein the EL layer has a hole transport layer and a light-emitting layer, the hole transport layer is located between the anode and the light-emitting layer, the hole transport layer and the anode are not in contact, and the hole transport layer comprises the material for the hole transport layer or the material for the electron transport layer.

[0037] Alternatively, another aspect of the present invention is a light-emitting device comprising an anode, a cathode, and an EL layer located between the anode and the cathode, wherein the EL layer comprises a hole injection layer, a hole transport layer, and a light-emitting layer, the hole injection layer and the hole transport layer located between the anode and the light-emitting layer, the hole transport layer located between the hole injection layer and the light-emitting layer, and the hole transport layer comprising the material for the hole transport layer.

[0038] Alternatively, another aspect of the present invention is a light-emitting device in which the hole transport layer and the light-emitting layer are in contact with each other in the above configuration.

[0039] Alternatively, another aspect of the present invention is a light-emitting device comprising an anode, a cathode, and an EL layer located between the anode and the cathode, wherein the EL layer comprises a hole injection layer, a hole transport layer, an electron blocking layer, and a light-emitting layer, wherein the hole injection layer, the hole transport layer, and the electron blocking layer are located between the anode and the light-emitting layer, the electron blocking layer is in contact with the light-emitting layer, the hole injection layer is in contact with the anode, and the electron blocking layer comprises a material for the electron blocking layer.

[0040] Alternatively, another aspect of the present invention is a light-emitting device in which, in the above configuration, the GSP_slope of the vapor-deposited film of the organic compound contained in the hole transport layer is smaller than the GSP_slope of the vapor-deposited film of the electron blocking layer material.

[0041] Alternatively, another aspect of the present invention is a light-emitting device in which, in the above configuration, the GSP_slope of the vapor-deposited film of the organic compound contained in the hole injection layer is less than 20 (mV / nm).

[0042] Alternatively, another aspect of the present invention is a light-emitting device having an anode, a cathode, and an EL layer located between the anode and the cathode, wherein the EL layer has an electron transport layer and a light-emitting layer, the electron transport layer is located between the cathode and the light-emitting layer, the electron transport layer and the cathode are not in contact, and the electron transport layer includes the electron transport layer material.

[0043] Alternatively, another aspect of the present invention is a light-emitting device comprising an anode, a cathode, and an EL layer located between the anode and the cathode, wherein the EL layer comprises an electron injection layer, an electron transport layer, and a light-emitting layer, the electron injection layer and the electron transport layer located between the cathode and the light-emitting layer, the electron transport layer located between the electron injection layer and the light-emitting layer, and the electron transport layer comprising the electron transport layer material.

[0044] Alternatively, another aspect of the present invention is a light-emitting device in which the electron transport layer and the light-emitting layer are in contact with each other in the above configuration.

[0045] Alternatively, another aspect of the present invention is a light-emitting device comprising an anode, a cathode, and an EL layer located between the anode and the cathode, wherein the EL layer comprises an electron injection layer, an electron transport layer, a hole blocking layer, and a light-emitting layer, wherein the electron injection layer, the electron transport layer, and the hole blocking layer are located between the cathode and the light-emitting layer, the hole blocking layer is in contact with the light-emitting layer, the electron injection layer is in contact with the cathode, and the hole blocking layer comprises the material for the hole blocking layer.

[0046] Alternatively, another aspect of the present invention is an electronic device having the light-emitting device described in any of the above, and a sensor, an operating button, a speaker, or a microphone.

[0047] Alternatively, another aspect of the present invention is a light-emitting device having the light-emitting device described in any of the above descriptions, a transistor, or a substrate.

[0048] Alternatively, another aspect of the present invention is a lighting device having a light-emitting device as described above and a housing.

[0049] In this specification, the term "light-emitting device" includes image display devices that use light-emitting devices. Furthermore, modules to which connectors, such as anisotropic conductive films or TCPs (Tape Carrier Packages), are attached to light-emitting devices, modules to which printed circuit boards are provided at the end of TCPs, or modules to which ICs (integrated circuits) are directly mounted using the COG (Chip On Glass) method may also be included as light-emitting devices. Additionally, lighting fixtures and the like may have light-emitting devices. [Effects of the Invention]

[0050] In one aspect of the present invention, any of the following materials can be provided: a hole transport layer material, an electron transport layer material, an electron block layer material, or a hole block layer material, capable of providing an organic semiconductor device with a low driving voltage. Alternatively, in one aspect of the present invention, any of the following materials can be provided: a transport layer material, a hole transport layer material, an electron transport layer material, an electron block layer material, or a hole block layer material, capable of providing a light-emitting device with a low driving voltage. Alternatively, in one aspect of the present invention, any of the following materials can be provided: a transport layer material, a hole transport layer material, an electron transport layer material, an electron block layer material, or a hole block layer material, capable of providing a photodiode sensor with a low driving voltage. Alternatively, in one aspect of the present invention, any of the following materials can be provided: a transport layer material, a hole transport layer material, an electron transport layer material, an electron block layer material, or a hole block layer material, capable of providing a light-emitting device, electronic device, display device, or electronic device with low power consumption.

[0051] Furthermore, in one aspect of the present invention, an organic semiconductor device with a low driving voltage can be provided. Alternatively, in one aspect of the present invention, a light-emitting device with a low driving voltage can be provided. Alternatively, in one aspect of the present invention, a photodiode sensor with a low driving voltage can be provided. Alternatively, in one aspect of the present invention, any of a light-emitting device, electronic device, display device, or electronic device with low power consumption can be provided.

[0052] Furthermore, the description of these effects does not preclude the existence of other effects. Moreover, one aspect of the present invention does not necessarily have to possess all of these effects. Other effects will naturally become apparent from the description in the specification, drawings, and claims, and it is possible to extract other effects from the description in the specification, drawings, and claims. [Brief explanation of the drawing]

[0053] [Figure 1] Figures 1(A) and 1(B) are diagrams representing a light-emitting device according to one embodiment of the present invention. [Figure 2] Figure 2 shows the capacitance-voltage characteristics of device 1 and device 2. [Figure 3] Figures 3(A), 3(B), and 3(C) are schematic diagrams of a light-emitting device according to one embodiment of the present invention. [Figure 4] Figures 4(A) to 4(D) show examples of the configuration of a display device. [Figure 5] Figures 5(A) to 5(F) show examples of methods for manufacturing a display device. [Figure 6] Figures 6(A) to 6(F) show examples of methods for manufacturing a display device. [Figure 7] Figure 7 is a perspective view showing an example of a display device. [Figure 8] Figures 8(A) and 8(B) are cross-sectional views showing an example of a display device. [Figure 9] Figure 9(A) is a cross-sectional view showing an example of a display device. Figure 9(B) is a cross-sectional view showing an example of a transistor. [Figure 10] Figures 10(A) and 10(B) are perspective views showing an example of a display module. [Figure 11] Figure 11 is a cross-sectional view showing an example of a display device. [Figure 12] Figure 12 is a cross-sectional view showing an example of a display device. [Figure 13] Figure 13 is a cross-sectional view showing an example of a display device. [Figure 14] Figure 14 shows an example of a display device configuration. [Figure 15] Figures 15(A) and 15(B) show examples of electronic devices. [Figure 16] Figures 16(A) to 16(D) show examples of electronic devices. [Figure 17] Figures 17(A) through 17(F) show examples of electronic devices. [Figure 18] Figures 18(A) through 18(F) show examples of electronic devices. [Figure 19] Figure 19 shows the luminance-current density characteristics of light-emitting devices D1 to D5, CD1, and CD2. [Figure 20] Figure 20 shows the current efficiency-luminance characteristics of light-emitting devices D1 to D5, CD1, and CD2. [Figure 21] Figure 21 shows the luminance-voltage characteristics of light-emitting devices D1 to D5, CD1, and CD2. [Figure 22] Figure 22 shows the current density-voltage characteristics of light-emitting devices D1 to D5, CD1, and CD2. [Figure 23] Figure 23 shows the external quantum efficiency-luminance characteristics of light-emitting devices D1 to D5, CD1, and CD2. [Figure 24] Figure 24 shows the power efficiency-luminance characteristics of light-emitting devices D1 to D5, CD1, and CD2. [Figure 25] Figure 25 shows the emission spectra of light-emitting devices D1 to D5, CD1, and CD2. [Figure 26] Figure 26 shows the luminance-current density characteristics of light-emitting devices D11 to D17, CD11, and CD12. [Figure 27] Figure 27 shows the current efficiency-luminance characteristics of light-emitting devices D11 to D17, CD11, and CD12. [Figure 28] Figure 28 shows the luminance-voltage characteristics of light-emitting devices D11 to D17, CD11, and CD12. [Figure 29] Figure 29 shows the current density-voltage characteristics of light-emitting devices D11 to D17, CD11, and CD12. [Figure 30] Figure 30 shows the external quantum efficiency-luminance characteristics of light-emitting devices D11 to D17, CD11, and CD12. [Figure 31] Figure 31 shows the power efficiency-luminance characteristics of light-emitting devices D11 to D17, CD11, and CD12. [Figure 32] Figure 32 shows the emission spectra of light-emitting devices D11 to D17, CD11, and CD12. [Figure 33] Figure 33 shows the 1H-NMR spectrum of ch3BichPAF. [Figure 34] Figure 34 shows the ultraviolet-visible absorption and emission spectra of ch3BichPAF in a toluene solution. [Figure 35] Figure 35 shows the 1H-NMR spectrum of mmtBuBichoBiF. [Figure 36]Figure 36 shows the ultraviolet-visible absorption and emission spectra of mmtBuBichoBiF in a toluene solution. [Figure 37] Figure 37 shows the MS spectrum of mmtBuBichoBiF. [Figure 38] Figures 38(A) and 38(B) are diagrams representing an active matrix type light-emitting device. [Figure 39] Figures 39(A) and 39(B) are diagrams representing an active matrix type light-emitting device. [Figure 40] Figure 40 is a diagram representing an active matrix type light-emitting device. [Modes for carrying out the invention]

[0054] The embodiments of the present invention will be described in detail below with reference to the drawings. However, it will be readily apparent to those skilled in the art that the present invention is not limited to the following description, and that its form and details can be modified in various ways without departing from the spirit and scope of the present invention. Accordingly, the present invention shall not be interpreted as being limited to the contents of the embodiments shown below.

[0055] In this specification, devices fabricated using a metal mask or FMM (Fine Metal Mask, a high-resolution metal mask) may be referred to as MM (Metal Mask) structured devices. In addition, in this specification, devices fabricated without using a metal mask or FMM may be referred to as MML (Metal Maskless) structured devices.

[0056] (Embodiment 1) Light-emitting devices are a type of organic semiconductor device that uses organic thin films. Other typical organic semiconductor devices include photodiode sensors and organic TFTs.

[0057] Many organic thin films used in such organic semiconductor devices are formed by vapor deposition. Organic thin films deposited by vapor deposition, which involves applying energy such as heat to the organic compound to be deposited and causing sublimation, have long been considered amorphous and randomly oriented, with the exception of films made of some materials that are prone to crystallization.

[0058] However, in recent years, numerous spectroscopic studies have revealed that even amorphous organic thin films can exhibit loose molecular orientation, which can affect the properties of devices. For example, in light-emitting devices, materials in which the dipole moment of the light-emitting material is easily oriented horizontally to the light-emitting surface are easier to extract light from and tend to provide light-emitting devices with high luminescence efficiency. Furthermore, materials in which superposition of π orbitals due to orientation is likely to occur tend to have high conductivity.

[0059] Incidentally, organic compounds include both polar and nonpolar molecules, and polar molecules possess a permanent dipole moment. When polar molecules are deposited, if the deposited film is perfectly randomly oriented, these polar biases cancel each other out, and no polarization originating from the polarity of the molecules occurs within the film. However, if the deposited film has some kind of bias, a giant surface potential may appear due to spontaneous polarization resulting from that bias.

[0060] Giant surface potential (GSP) is a phenomenon in which the surface potential of a deposited film increases in proportion to its film thickness. To treat its magnitude as a value independent of film thickness, one can use the value obtained by dividing the surface potential of the deposited film by its film thickness, i.e., the potential gradient (slope) of the surface potential of the deposited film. In this specification, this potential gradient of the surface potential of the deposited film is denoted as GSP_slope(mV / nm).

[0061] Due to the enormous surface potential, the surface potential of the deposited film increases at a constant rate with increasing film thickness without saturating. For example, a deposited film of tris(8-quinolinolato)aluminum (abbreviated as Alq3) reaches a surface potential of approximately 28V at a film thickness of 560nm. This electric field strength is 5 × 10⁻¹⁰5 It reaches V / cm, which is about the same magnitude as the electric field strength during the operation of typical organic thin-film devices.

[0062] In this study, the inventors discovered that by using a material with a large GSP_slope (20 mV / nm or more) as the material for the carrier transport layer away from the electrodes, the driving voltage of the light-emitting device can be significantly reduced. In this specification, the GSP_slope value is defined as the value calculated by measuring an organic compound film of approximately 80 nm that is the subject of the measurement.

[0063] Figure 1(A) shows a schematic diagram of a light-emitting device according to one embodiment of the present invention. In the light-emitting device according to one embodiment of the present invention, an EL layer 50 is provided between a first electrode 10 and a second electrode 30, and the EL layer 50 has at least a light-emitting layer 40 and a layer 21 containing a carrier transport layer material with a large GSP_slope of the deposited film (20mV / nm or more).

[0064] Layer 21 contains a carrier transport layer material with a large GSP_slope (20mV / nm or more) in the deposited film, resulting in a potential difference within the layer due to polarization. Furthermore, negative polarization occurs on the first electrode side of layer 21, which attracts holes to the interface, promoting hole injection and resulting in a decrease in the driving voltage.

[0065] Furthermore, for the carrier transport layer material of the deposited film, which has a large GSP_slope (20mV / nm or more), it is preferable that the GSP_slope is 100mV / nm or less in order to reduce the driving voltage.

[0066] In Figure 1(A), layer 21 functions as a hole transport layer and is not in contact with the first electrode 10. Therefore, a carrier implantation layer 20 (hole implantation layer in Figure 1(A)) exists between the first electrode and layer 21, and is in contact with the electrode. In one aspect of the present invention, it is preferable that the GSP_slope of the material constituting the carrier implantation layer 20 is small (less than 20mV / nm).

[0067] Furthermore, it is preferable that layer 21 is in contact with the light-emitting layer 40, as this improves the carrier injection into the light-emitting layer. In this case, it is even more preferable that layer 21 functions as a carrier blocking layer (electron blocking layer in Figure 1(A)). When layer 21 functions as an electron blocking layer, it is preferable that the LUMO level of the material it contains is 0.5 eV or higher than the lowest LUMO level of the material contained in the light-emitting layer.

[0068] The hole transport layer may have a multilayer structure consisting of multiple layers. In this case, the layer containing the carrier transport layer material with a large GSP_slope (20mV / nm or more) of the deposited film (layer 21) may be any one of the layers in the multilayer structure. It is preferable that layer 21 is the hole transport layer closest to the light-emitting layer in the multilayer structure, as this improves hole injection performance. In this case, it is even more preferable that layer 21 functions as an electron blocking layer. Furthermore, it is preferable that the GSP_slope of the other layers constituting the hole transport layer is lower than the GSP_slope of layer 21, as this improves hole injection performance. The GSP_slope of the other layers constituting the hole transport layer other than layer 21 may be less than 20mV / nm.

[0069] As shown in Figure 1(A), when layer 21 is a hole transport layer provided between the first electrode 10, which is the anode, and the light-emitting layer 40, the carrier transport layer material with a large GSP_slope of the deposited film contained in the layer preferably has hole transport properties, and is more preferably an arylamine because it has good hole transport properties.

[0070] Figure 1(B) is a schematic diagram of a light-emitting device according to another embodiment of the present invention. The difference between Figure 1(B) and Figure 1(A) is that layer 21 is provided between the light-emitting layer 40 and the second electrode 30 and functions as an electron transport layer. Note that layer 21 is not in contact with the second electrode 30, and a carrier injection layer 20 (electron injection layer in Figure 1(B)) exists between layer 21 and the second electrode 30. In one embodiment of the present invention, a small GSP_slope (less than 20mV / nm) of the material constituting the carrier injection layer 20 is a preferred configuration for reducing the driving voltage.

[0071] Layer 21 contains a carrier transport layer material with a large GSP_slope (20mV / nm or more) in the deposited film, resulting in a potential difference within the layer due to polarization. Since positive polarization occurs on the second electrode side of layer 21, electrons are attracted to the interface, promoting electron injection and resulting in a decrease in the driving voltage.

[0072] Furthermore, it is preferable that layer 21 is in contact with the light-emitting layer 40, as this improves electron injection. In this case, it is even more preferable that layer 21 functions as a carrier block layer (hole block layer in Figure 1(B)). When layer 21 functions as a hole block layer, it is preferable that the HOMO level of the material it contains is 0.5 eV or more deeper than the HOMO level of the host material contained in the light-emitting layer.

[0073] The electron transport layer may have a multilayer structure consisting of multiple layers. In this case, the layer containing the carrier transport layer material with a large GSP_slope (20mV / nm or more) of the deposited film (layer 21) may be any one of the layers in the multilayer structure. It is preferable that layer 21 is the electron transport layer closest to the light-emitting layer in the multilayer structure, as this improves hole injection performance. In this case, it is even more preferable that layer 21 functions as a hole-blocking layer. Furthermore, it is preferable that the GSP_slope of the other electron transport layers be lower than the GSP_slope of layer 21, as this improves electron injection performance. The GSP_slope of the other electron transport layers may be less than 20mV / nm.

[0074] A light-emitting device according to one aspect of the present invention having the above configuration can be made into a light-emitting device with good characteristics of low driving voltage.

[0075] Incidentally, it is known that providing a low refractive index layer in the EL layer of a light-emitting device improves extraction efficiency, resulting in a light-emitting device with high efficiency. It is preferable to provide this low refractive index layer in a layer close to the light-emitting layer, as this configuration yields a greater effect.

[0076] On the other hand, there is a trade-off between low refractive index and carrier transport performance. This is because carrier transport performance in organic compounds largely depends on the presence of unsaturated bonds, and organic compounds with many unsaturated bonds tend to have high refractive indices. Therefore, even if the current efficiency of a light-emitting device using a carrier transport material with a low refractive index improves, the driving voltage increases, and the expected reduction in power consumption may not be achieved.

[0077] Here, the inventors have found that by providing a material with a low refractive index and a large GSP_slope near the light-emitting layer, a light-emitting device with high current efficiency and suppressed rise in driving voltage can be realized. Both the low refractive index layer and the large GSP_slope layer are more effective when provided close to the light-emitting layer. Therefore, by providing a material with a low refractive index and a large GSP_slope near the light-emitting layer, it is possible to obtain a light-emitting device with low power consumption and a light-emitting device exhibiting very good power efficiency.

[0078] Therefore, it is preferable that the refractive index of the carrier transport layer material, which has a large GSP_slope in the above-mentioned deposited film, is low. Specifically, it is preferable that the ordinary refractive index of the material for light with a wavelength of 450 nm is 1.50 or more and 1.75 or less, or for light with a wavelength of 633 nm, 1.45 or more and 1.70 or less.

[0079] Furthermore, from the viewpoint of maintaining a low refractive index, if the material has condensed aromatic hydrocarbon rings, it is preferable that the condensed aromatic hydrocarbon rings consist of three or fewer condensed aromatic rings (e.g., anthracene rings, naphthalene rings, fluorene rings), and that the total number of such condensed aromatic hydrocarbon rings contained in the material molecule is one or two. In addition, while it is preferable to have a fluorene skeleton in the molecule to improve hole transportability, from the viewpoint of maintaining a low refractive index, it is preferable that the number of fluorene skeletons in the molecule of the material is two or less.

[0080] Furthermore, in order to obtain a material with a low refractive index, it is preferable to introduce substituents with low molecular refraction into the molecule. Examples of such substituents include saturated hydrocarbon groups and cyclic saturated hydrocarbon groups. Therefore, for carrier transport layer materials with a large GSP_slope of the vapor-deposited film, it is preferable to have at least three chain alkyl groups having 2 to 5 carbon atoms or cycloalkyl groups having 6 to 12 carbon atoms, and particularly branched chain alkyl groups having 3 to 5 carbon atoms. Among the chain alkyl groups having 2 to 5 carbon atoms or cycloalkyl groups having 6 to 12 carbon atoms, t-butyl groups and cyclohexyl groups are particularly preferred.

[0081] Furthermore, the presence of multiple t-butyl groups and cyclohexyl groups improves heat resistance. It is desirable to use a carrier transport layer material with a large GSP_slope of the above-mentioned deposited film, which has a glass transition temperature (Tg) of 100°C or higher, preferably 110°C or higher, and more preferably 120°C or higher.

[0082] Furthermore, chain alkyl groups having 2 to 5 carbon atoms or cycloalkyl groups having 6 to 12 carbon atoms are composed of carbon atoms that form bonds in sp3 hybrid orbitals. Since carbon atoms that form bonds in sp3 hybrid orbitals have a low refractive index, a higher proportion of carbon atoms that form bonds in sp3 hybrid orbitals relative to the total number of carbon atoms in the molecule allows for a material with a lower refractive index. However, considering carrier transport, it is preferable that the proportion of carbon atoms that form bonds in sp3 hybrid orbitals relative to the total number of carbon atoms in the molecule is between 23% and 55%.

[0083] Furthermore, the signal of the carbon atoms forming bonds in the sp3 hybrid orbitals is 1 The results of material measurements using 1H-NMR showed a value of less than 4 ppm. Therefore, a carrier transport layer material with a large GSP_slope in the deposited film is used. 1 When measured by 1H-NMR, it is preferable that the integrated value of signals below 4 ppm exceeds the integrated value of signals above 4 ppm.

[0084] Furthermore, carrier transport layer materials with a large GSP_slope in such deposited films can also be suitably used in sensors such as photodiodes.

[0085] Here, we will explain how to determine the GSP_slope of an organic compound.

[0086] The phenomenon in which the surface potential of a deposited film increases in proportion to its thickness is called giant surface potential, as mentioned above. Generally, the slope when the surface potential of a deposited film measured by a Kelvin probe is plotted in the direction of film thickness is discussed as the magnitude of the giant surface potential, i.e., GSP_slope (mV / nm). However, when two different layers are stacked, the polarization charge density (mC / m) accumulated at their interface... 2 By utilizing the fact that ) changes in relation to GSP_slope, we can estimate GSP_slope.

[0087] Non-patent document 1 shows that when organic thin films with different spontaneous polarizations (thin film 1 and thin film 2, where thin film 1 is on the anode side and thin film 2 is on the cathode side) are stacked and an electric current is passed through them, the following equation holds true.

[0088]

number

[0089]

number

[0090] In equation (1), σ ifis the polarization charge density, V i is the hole injection voltage, V bi is the threshold voltage, d2 is the film thickness of the thin film 2, and ε2 is the dielectric constant of the thin film 2. V i , V bi can be estimated from the capacitance-voltage characteristics of the device. Also, the dielectric constant can use the square of the ordinary light refractive index n o (633 nm). Thus, from the capacitance-voltage characteristics, the estimated V i , V bi , the dielectric constant ε2 of the thin film 2 calculated from the refractive index, and the film thickness d2 of the thin film 2, the polarization charge density σ if can be obtained using Equation (1).

[0091] Subsequently, in Equation (2), σ if is the polarization charge density, P n is the GSP_slope of the thin film n, and ε n is the dielectric constant of the thin film n. Here, since the polarization charge density σ if can be obtained from Equation (1) above, by using a material with a known GSP_slope as the thin film 2, the GSP_slope of the thin film 1 can be estimated.

[0092] Therefore, Alq3 with a known GSP_slope of (48 mV / nm) was used as the thin film 2, and devices 1 and 2 were fabricated as measurement devices. An example of obtaining the GSP_slope of mmtBumTPoFBi-02 for device 1 and NPB for device 2 is shown below.

[0093] The device structures of device 1 and device 2 are as shown in the following table. For layer 1_1 to the cathode in device 1 and device 2, from the anode side, they were formed by vacuum evaporation method under the conditions of a substrate temperature of room temperature and a film formation rate of 0.2 nm / sec to 0.4 nm / sec. Note that film formation was carried out without stopping evaporation during the formation of one layer. In device 1 and device 2, layer 2_1 corresponds to the thin film 1 and layer 3_1 corresponds to the thin film 2.

[0094] Also, the capacitance-voltage characteristics of device 1 and device 2 are shown in Figure 2.

[0095] [Table 1]

[0096] Table 2 shows the hole injection voltages V for device 1 (mmtBumTPoFBi-02) and device 2 (NPB), calculated using Figure 2 and equations (1) and (2). i , threshold voltage V bi , polarization charge density σ if , GSP_slope and the refractive index n of each material used in the calculation o This indicates.

[0097] [Table 2]

[0098] Furthermore, devices 3 and 4, which have almost the same configuration as devices 1 and 2 but with an Alq3 film thickness of 80 nm, were fabricated, and it was confirmed that the hole injection voltage for each was shifted to a lower voltage than that of devices 1 and 2. This suggests that in such devices, holes are injected first, and polarization charge accumulates at the interface with Alq3. In addition, GSP_slope estimation was performed using devices 3 and 4, similar to devices 1 and 2, and it was confirmed that the same results were obtained.

[0099] Thus, by fabricating a device in which Alq3, whose GSP_slope is known, and an organic compound whose GSP_slope is to be determined are stacked, and measuring the capacitance-voltage characteristics, the GSP_slope can be estimated.

[0100] If thin film 1 or thin film 2 contains multiple organic compounds, the GSP_slope of the organic compound that is primarily present (for example, the one present in the largest quantity) can be considered as the "GSP_slope of the material constituting the layer." Alternatively, if thin film 1 or thin film 2 contains multiple organic compounds, the GSP_slope and content of each organic compound can be calculated, and their weighted average (GSP_slope_ave) can be defined as the "GSP_slope of the material constituting the layer."

[0101] (Embodiment 2) This embodiment describes in detail a light-emitting device according to one aspect of the present invention. Figure 3(A) shows a diagram representing a light-emitting device according to one aspect of the present invention. The light-emitting device according to one aspect of the present invention has an EL layer 103 between a first electrode 101 and a second electrode 102. The EL layer 103 has a light-emitting layer 113 and a layer containing a material with a large GSP_slope of the deposited film (electron blocking layer 120 in this embodiment).

[0102] The region between the light-emitting layer 113 and the first electrode 101 is a hole transport region with holes as carriers, and the region between the light-emitting layer 113 and the second electrode 102 is an electron transport region with electrons as carriers. If the hole transport region contains a layer made of a material with a large GSP_slope of the deposited film, that layer functions as both a hole transport layer and an electron blocking layer. If the layer is located in the electron transport region, it functions as both an electron transport layer and a hole blocking layer.

[0103] Furthermore, the light-emitting device is formed sequentially starting from the first electrode 101, which functions as an anode.

[0104] Between the hole transport layer 112 and the first electrode 101, a hole injection layer 111 is provided in contact with the first electrode 101, and in this invention, the hole transport layer and the electron blocking layer 120 do not come into contact with the electrode. When a layer containing a material with a large GSP_slope of the deposited film is formed in the electron transport region, the light-emitting device has an electron injection layer 115 in contact with the second electrode 102, which is the cathode, and the electron transport layer and the hole blocking layer do not come into contact with the second electrode.

[0105] Although Figure 3(A) also shows an electron transport layer 114 and an electron injection layer 115, the configuration of the light-emitting device is not limited to these, and may include other functional layers such as a carrier block layer, an exciton block layer, and a charge generation layer.

[0106] Next, we will describe the detailed structure and material examples of the light-emitting devices mentioned above.

[0107] The first electrode 101, which functions as an anode, is preferably formed using a metal, alloy, conductive compound, or mixture thereof with a large work function (specifically, 4.0 eV or more). Specifically, examples include indium tin oxide (ITO), indium tin oxide containing silicon or silicon oxide, indium zinc oxide, and indium oxide (IWZO) containing tungsten oxide and zinc oxide. These conductive metal oxide films are usually deposited by sputtering, but they may also be fabricated using methods such as the sol-gel method. An example of a fabrication method is to form indium zinc oxide by sputtering using a target to which 1 to 20 wt% zinc oxide is added to indium oxide. Furthermore, indium oxide (IWZO) containing tungsten oxide and zinc oxide can also be formed by sputtering using a target containing 0.5-5 wt% tungsten oxide and 0.1-1 wt% zinc oxide relative to indium oxide. Other materials include gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), or nitrides of metallic materials (e.g., titanium nitride). Graphene can also be used. By using the composite material described later in the hole injection layer 111, the electrode material can be selected regardless of the work function.

[0108] The hole injection layer 111 contains an acceptor-like substance and is a layer in contact with the first electrode 101. Both organic and inorganic compounds can be used as the acceptor-like substance.

[0109] Examples of substances with acceptor properties include compounds having electron-withdrawing groups (halogen groups, cyano groups, etc.), such as 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviated as F4-TCNQ), chloranil, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexazatriphenylene (abbreviated as HAT-CN), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviated as F6-TCNNQ), and 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyrene-2-ylidene)malononitrile. In particular, compounds in which an electron-withdrawing group is bonded to a condensed aromatic ring having multiple heteroatoms, such as HAT-CN, are thermally stable and preferred. Furthermore, radialene derivatives having an electron-withdrawing group (especially halogen groups such as fluoro groups, cyano groups, etc.) are preferred because they have very high electron-accepting properties. Specific examples include α,α',α''-1,2,3-cyclopropanetriylidenates[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α',α''-1,2,3-cyclopropanetriylidenates[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], and α,α',α''-1,2,3-cyclopropanetriylidenates[2,3,4,5,6-pentafluorobenzeneacetonitrile]. In addition to the organic compounds mentioned above, other substances with acceptor properties that can be used include molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, manganese oxide, etc. Furthermore, the hole injection layer 111 can also be formed by phthalocyanine-based complex compounds such as phthalocyanine (abbreviated as H2Pc) and copper phthalocyanine (CuPc), aromatic amine compounds such as 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviated as DPAB) and N,N'-bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviated as DNTPD), or polymers such as poly(3,4-ethylenedioxythiophene) / poly(styrene sulfonic acid) (PEDOT / PSS).Acceptor materials can extract electrons from adjacent hole transport layers (or hole transport materials) by applying an electric field.

[0110] Furthermore, a composite material containing the above-mentioned acceptor substance in a hole-transporting material can also be used as the hole injection layer 111. By using a composite material containing the acceptor substance in a hole-transporting material, it is possible to select the material for forming the electrode regardless of the work function. In other words, not only materials with a large work function but also materials with a small work function can be used as the first electrode 101.

[0111] Various organic compounds can be used as hole-transporting materials in composite materials, including aromatic amine compounds, carbazole derivatives, aromatic hydrocarbons, and polymer compounds (oligomers, dendrimers, polymers, etc.). -6 cm 2 It is preferable that the material has a hole mobility of / Vs or higher. Below, we specifically list organic compounds that can be used as hole transporting materials in composite materials.

[0112] Aromatic amine compounds that can be used in composite materials include N,N'-di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviated as DTDPPA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviated as DPAB), N,N'-bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviated as DNTPD), and 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviated as DPA3B). Specifically, carbazole derivatives include 3-[N-(9-phenylcarbazole-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviated as PCzPCA1), 3,6-bis[N-(9-phenylcarbazole-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviated as PCzPCA2), and 3-[N-(1-naphthyl)-N-(9-phenylcarbazole-3-yl)amino]-9-phenylcarbazole Examples of substances that can be used include bazole (abbreviated as PCzPCN1), 4,4'-di(N-carbazolyl)biphenyl (abbreviated as CBP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviated as TCPB), 9-[4-(10-phenylanthracene-9-yl)phenyl]-9H-carbazole (abbreviated as CzPA), and 1,4-bis[4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene.Examples of aromatic hydrocarbons include 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 2-tert-butyl-9,10-di(1-naphthyl)anthracene, 9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA), 2-tert-butyl-9,10-bis(4-phenylphenyl)anthracene (abbreviation: t-BuDBA), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA), 9,10-diphenylanthracene (abbreviation: DPAnth), 2-tert-butylanthracene (abbreviation: t-BuAnth), 9,10-bis(4-methyl-1-naphthyl)anthracene (abbreviation: DMNA), 2-tert- Examples include butyl-9,10-bis[2-(1-naphthyl)phenyl]anthracene, 9,10-bis[2-(1-naphthyl)phenyl]anthracene, 2,3,6,7-tetramethyl-9,10-di(1-naphthyl)anthracene, 2,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene, 9,9'-bianthryl, 10,10'-diphenyl-9,9'-bianthryl, 10,10'-bis(2-phenylphenyl)-9,9'-bianthryl, 10,10'-bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9'-bianthryl, anthracene, tetracene, rubrene, perylene, and 2,5,8,11-tetra(tert-butyl)perylene. In addition, pentacene, coronene, and the like can also be used. They may have a vinyl skeleton. Examples of aromatic hydrocarbons having a vinyl group include 4,4'-bis(2,2-diphenylvinyl)biphenyl (abbreviated as DPVBi) and 9,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene (abbreviated as DPVPA).

[0113] Furthermore, polymer compounds such as poly(N-vinylcarbazole) (abbreviated as PVK), poly(4-vinyltriphenylamine) (abbreviated as PVTPA), poly[N-(4-{N'-[4-(4-diphenylamino)phenyl]phenyl-N'-phenylamino}phenyl)methacrylamide] (abbreviated as PTPDMA), and poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine] (abbreviated as Poly-TPD) can also be used.

[0114] Furthermore, the hole-transporting material used in the composite material is more preferably one of the following: a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, or an anthracene skeleton. In particular, it may be an aromatic amine having substituents including 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 these hole-transporting materials are substances having an N,N-bis(4-biphenyl)amino group, as this allows for the creation of light-emitting devices with a good lifetime. Examples of materials possessing the hole transport properties 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), and 4,4'-bis(6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine). N-8-yl)-4''-phenyltriphenylamine (abbreviation: BnfBB1BP), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-6-amine (abbreviation: BBABnf(6)), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf(8)), N,N-bis(4-biphenyl)benzo[b]naphtho[2,3- d]furan-4-amine (abbreviation: BBABnf(II)(4)), N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP), N-[4-(dibenzothiophen-4-yl)phenyl]-N-phenyl-4-biphenylamine (abbreviation: ThBA1BP), 4-(2-naphthyl)-4',4''-diphenyltriphenylamine (abbreviation) Name: 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)triphenyl Luamine (abbreviation: αNBA1BP), 4,4'-bis(1-naphthyl)triphenylamine (abbreviation: αNBB1BP), 4,4'-diphenyl-4''-[4'-(carbazole-9-yl)biphenyl-4-yl]triphenylamine (abbreviation: YGTBi1BP), 4'-[4-(3-phenyl-9H-carbazole-9-yl)phenyl]tris(1,1'-biphenyl-4-yl)amine (abbreviation: YGTBi1BP-02), 4-diphenyl-4'-(2-naphthyl)-4''-{9-(4-biphenylyl)carbazole}triphenylamine N (abbreviation: YGTBiβNB), N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-N-[4-(1-naphthyl)phenyl]-9,9'-spirobio[9H-fluorene]-2-amine (abbreviation: PCBNBSF), N,N-bis(4-biphenylyl)-9,9'-spirobio[9H-fluorene]-2-amine (abbreviation: BBASF), N,N-bis(1,1'-biphenyl-4-yl)-9,9'-spirobio[9H-fluorene]-4-amine (abbreviation: BBASF(4)), N-(1,1'-biphenyl-2-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi[9H-fluoren]-4-amine (abbreviation: oFBiSF), N-(4-biphenyl)-N-(dibenzofuran-4-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: FrBiF), N-[4-(1-naphthyl)phenyl]-N-[3-(6-phenyldibenzofuran-4-yl)phenyl]-1-naphthylamine (abbreviation: mPDBfBNBN), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4 -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-carbazole-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H -Carbazole-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBNBB), N-phenyl-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]spiro-9,9'-bifluoren-2-amine (abbreviation: PCBASF), N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine Examples include (abbreviation: PCBBiF), N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobio-9H-fluoren-4-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobio-9H-fluoren-3-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobio-9H-fluoren-2-amine, and N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobio-9H-fluoren-1-amine.

[0115] Furthermore, it is even more preferable that the hole-transporting material used in the composite material has a relatively deep HOMO level between -5.7 eV and -5.4 eV. Having a relatively deep HOMO level in the hole-transporting material used in the composite material facilitates the injection of holes into the hole transport layer 112 and makes it easier to obtain a light-emitting device with a good lifetime.

[0116] Furthermore, by further mixing alkali metal or alkaline earth metal fluoride into the composite material (preferably with an atomic ratio of fluorine atoms of 20% or more in the layer), the refractive index of the layer can be reduced. This also allows for the formation of a layer with a low refractive index inside the EL layer 103, thereby improving the external quantum efficiency of the light-emitting device.

[0117] By forming the hole injection layer 111, the hole injection performance is improved, making it possible to obtain a light-emitting device with a low driving voltage. Furthermore, organic compounds with acceptor properties are easy to deposit and form films with, making them easy to use materials.

[0118] Furthermore, the material used for the hole injection layer 111 is preferably one with a GSP_slope of less than 20mV / nm, as this makes it easier to obtain a light-emitting device with a lower driving voltage. Therefore, it is preferable to form the hole injection layer 111 using a material with a GSP_slope of less than 20mV / nm from among the materials mentioned above.

[0119] The hole transport layer 112 is formed by including a material having hole transport properties. The material having hole transport properties is 1 × 10 -6 cm 2 It is preferable that the hole mobility is greater than or equal to / Vs.

[0120] Furthermore, in a light-emitting device according to one aspect of the present invention, it is preferable that the hole transport layer 112 contains a material with a GSP_slope of 20 mV / nm or more. The hole transport layer 112 may be composed of layers made of multiple different materials, in which case it is sufficient to have at least one layer containing a material with a GSP_slope of 20 mV / nm or more, preferably a layer composed of a material with a GSP_slope of 20 mV / nm or more. Furthermore, it is preferable that the layer containing the material with a GSP_slope of 20 mV / nm or more is a layer close to the light-emitting layer, and more preferably in contact with the light-emitting layer. In this case, it is even more preferable that the layer containing the material with a GSP_slope of 20 mV / nm or more has the function of an electron blocking layer.

[0121] Light-emitting devices with such a configuration allow for easy hole injection and enable the use of organic semiconductor devices with low driving voltages.

[0122] Organic compounds that can be used in the hole transport layer 112 include 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviated as NPB), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviated as TPD), 4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviated as BSPB), and 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenyl Amine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-phenyl-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine Aromatic compounds such as mine (abbreviated as PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviated as PCBNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]fluoren-2-amine (abbreviated as PCBAF), and N-phenyl-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]spiro-9,9'-bifluoren-2-amine (abbreviated as PCBASF). Compounds having a amine skeleton, compounds having a carbazole skeleton such as 1,3-bis(N-carbazolyl)benzene (abbreviated as mCP), 4,4'-di(N-carbazolyl)biphenyl (abbreviated as CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviated as CzTP), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviated as PCCP), 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviated as DBT3P-II), 2,Examples include compounds having a thiophene skeleton such as 8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviated as DBTFLP-III) and 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviated as DBTFLP-IV), and compounds having a furan skeleton such as 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviated as DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviated as mmDBFFLBi-II). Among the above, compounds having an aromatic amine skeleton and compounds having a carbazole skeleton are preferred because they have good reliability, high hole transportability, and contribute to reducing the driving voltage. Furthermore, the organic compounds listed as usable in the composite material of the hole injection layer 111 can also be suitably used as materials constituting the hole transport layer 112. Layers containing materials with a large GSP_slope can be formed using materials with a GSP_slope of 20 mV / nm or higher from among these options.

[0123] Furthermore, it is preferable that the material forming the hole transport layer has at least three C2 to C5 chain alkyl groups or C6 to C12 cycloalkyl groups, particularly C3 to C5 branched chain alkyl groups, as this can lower the refractive index of the hole transport layer 112 and improve the light extraction efficiency. Examples of such materials include N,N-bis(4-cyclohexylphenyl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviated as dchPAF), N-[(4'-cyclohexyl)-1,1'-biphenyl-4yl]-N-(4-cyclohexylphenyl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviated as chBichPAF), and N,N-bis(4-cyclohexylphenyl)-N-(spiro[cyclohexane-1,9'[9 [H]fluoren]-2'yl)amine (abbreviation: dchPASchF), N-[(4'-cyclohexyl)-1,1'-biphenyl-4yl]-N-(4-cyclohexylphenyl)-N-(spiro[cyclohexane-1,9'-[9H]fluoren]-2'yl)amine (abbreviation: chBichPASchF), N-(4-cyclohexylphenyl)-bis(spiro[cyclohexane-1,9'-[9H]fluoren]-2'-yl)amine (abbreviation: Sc hFB1chP), N-[(3',5'-ditterbutyl)-1,1'-biphenyl-4-yl]-N-(4-cyclohexylphenyl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBuBichPAF), N,N-bis(3',5'-ditterbutyl-1,1'-biphenyl-4-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: dmmtBuBiAF), N-(3,5-ditterbutyl Phenyl)-N-(3',5',-Diter-butyl-1,1'-biphenyl-4-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBuBimmtBuPAF), N,N-bis(4-cyclohexylphenyl)-9,9-dipropyl-9H-fluoren-2-amine (abbreviation: dchPAPrF), N-[(3',5'-dicyclohexyl)-1,1'-biphenyl-4-yl]-N-(4-cyclohexylphenyl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmchBichPAF), N-(3,3'',5,5''-tetra-t-butyl-1,1':3',1''-terphenyl-5'-yl)-N-(4-cyclohexylphenyl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPchPAF), N-(4-cyclododecylphenyl)-N-(4-cyclohexylphenyl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: CdoPchPAF), N-(3,3'',5,5''-tetra-t-butyl -1,1':3',1''-terphenyl-5'-yl)-N-phenyl-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPFA), N-(1,1'-biphenyl-4-yl)-N-(3,3'',5,5''-tetra-t-butyl-1,1':3',1''-terphenyl-5'-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPFBi), 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), N-[(3,3',5'-tri-t-butyl)-1,1'-biphenyl-5-yl]-N-(4-cyclohexylphenyl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumBichPAF), N-(1,1'-biphenyl-2-yl)-N-[(3,3',5'-tri-t-butyl)-1,1'-biphenyl-5-yl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumBioFBi), N-(4-tert-butylphenyl)-N-(3,3'',5,5''-tetra-t-butyl-1,1':3',1''-terphenyl-5'-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPtBuPAF), N-(3,3'',5',5''-tetra-tert-butyl-1,1':3',1''-terphenyl-5-yl)-N-phenyl-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPFA-02), N-(1,1'-biphenyl-4-yl)-N-(3,3'',5',5''-Tetra-tert-butyl-1,1':3',1''-terphenyl-5-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPFBi-02), N-(1,1'-biphenyl-2-yl)-N-(3,3'',5',5''-tetra-tert-butyl-1,1':3',1''-terphenyl-5-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPoFBi-02), N-(4-cyclohexylphenyl)-N-(3,3'',5',5''-tetra -tert-butyl-1,1':3',1''-terphenyl-5-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPchPAF-02), N-(1,1'-biphenyl-2-yl)-N-(3'',5',5''-tri-tert-butyl-1,1':3',1''-terphenyl-5-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPoFBi-03), N-(4-cyclohexylphenyl)-N-(3'',5',5''-tri-tert-butyl-1, 1':3',1''-terphenyl-5-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPchPAF-03), N-(1,1'-biphenyl-2-yl)-N-(3'',5',5''-tri-tert-butyl-1,1':3',1''-terphenyl-4-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPoFBi-04), N-(4-cyclohexylphenyl)-N-(3'',5',5''-tri-tert-butyl-1,1':3',1''-ta -phenyl-4-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPchPAF-04), N-(1,1'-biphenyl-2-yl)-N-(3,3'',5''-tri-tert-butyl-1,1':4',1''-terphenyl-5-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPoFBi-05), N-(4-cyclohexylphenyl)-N-(3,3'',5''-tri-tert-butyl-1,1':4',1''-terphenyl-5-yl)-9,Preferred compounds include 9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPchPAF-05), N-(3',5'-diter-butyl-1,1'-biphenyl-4-yl)-N-(1,1'-biphenyl-2-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBuBioFBi), N-2',4',6'-tricyclohexyl-1,1'-biphenyl-4-yl-N-(4-cyclohexylphenyl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: ch3BichPAF), and N-(3',5'-di-t-butylbiphenyl-4-yl)-N-(4-cyclohexyl-biphenyl-2-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBuBichoBiF). Layers containing materials with a large GSP_slope can be formed using materials with a GSP_slope of 20mV / nm or higher from among these materials.

[0124] Among these, ch3BichPAF, mmtBuBichoBiF, mmtBuBiFF-02, mmtBumTPoFBi-02, mmtBuBichPAF, mmtBuBioBitBu2FLP(2), mmtBuBiFF, mmtBumTPchPAF-04, and mmtBuBioFBi have a GSP_slope of 20mV / nm or more, making it easy to obtain light-emitting devices with low drive voltages by using them as carrier transport materials with a large GSP_slope. Furthermore, since these materials also have the characteristic of having a low refractive index, using them as materials to constitute the hole transport layer and electron blocking layer makes it possible to obtain light-emitting devices with very good characteristics, such as low drive voltage and high current efficiency.

[0125] The light-emitting layer 113 contains a light-emitting substance and a host material. The light-emitting layer 113 may also contain other materials. Furthermore, it may be a laminate of two layers with different compositions.

[0126] The luminescent material can be a fluorescent material, a phosphorescent material, a material that exhibits thermally activated delayed fluorescence (TADF), or any other luminescent material.

[0127] Examples of materials that can be used as fluorescent materials in the light-emitting layer 113 include the following. Other fluorescent materials can also be used.

[0128] 5,6-Bis[4-(10-phenyl-9-antryl)phenyl]-2,2'-bipyridine (abbreviation: PAP2BPy), 5,6-Bis[4'-(10-phenyl-9-antryl)biphenyl-4-yl]-2,2'-bipyridine (abbreviation: PAPP2BPy), N,N'-Diphenyl-N,N'-Bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyren-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 (abbreviation: 1,6mMemFLPAPrn), N,N'-bis[4-(9H-carbazole-9-yl)phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-carbazole-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), 4-(9H-carbazole-9-yl)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-diphenyl-N-[4-( 10-phenyl-9-anthryl)phenyl]-9H-carbazole-3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetra-tert-butylperylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: 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-carbazole-3-amine (abbreviation: 2PCAPPA), 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: 2DPAB) PhA), 9,10-bis(1,1'-biphenyl-2-yl)-N-[4-(9H-carbazole-9-yl)phenyl]-N-phenylanthracene-2-amine (abbreviation: 2YGABPhA), N,N,9-triphenylanthracene-9-amine (abbreviation: DPhAPhA), coumarin 545T, N,N'-diphenylquinacridone (abbreviation: DPQd), rubren, 5,12-bis(1,1'-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6 -methyl-4H-pyran-4-ylidene)propanedinitrile (abbreviation: DCM1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinoridine-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]fluorantene-3,10-di Amine (abbreviation: p-mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinoridine-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinoridine-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]quinoridine-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJTM), N,N'-diphenyl-N,N'-(1,6-pyrene-diyl)bis[(6-phenylbenzo[b Examples include ]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-03), 3,10-bis[N-(9-phenyl-9H-carbazole-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, such as pyrenediamine compounds like 1,6FLPAPrn, 1,6mMemFLPAPrn, and 1,6BnfAPrn-03, are preferred because they have high hole-trapping properties and excellent luminescence efficiency and reliability.

[0129] When a phosphorescent material is used as the light-emitting material in the light-emitting layer 113, the following are some examples of materials that can be used.

[0130] Organometallic iridium complexes having a 4H-triazole skeleton, such as Tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN2]phenyl-κC}iridium(III) (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)3]), Tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III) ( Abbreviation: [Ir(Mptz1-mp)3]), organometallic iridium complexes having a 1H-triazole skeleton such as tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Prptz1-Me)3]), organometallic iridium complexes having an imidazole 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]phenantridinato]iridium(III) (abbreviation: [Ir(dmpimpt-Me)3]), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ Iridium(III) tetrakis(1-pyrazolyl) borate (abbreviation: FIr6), bis[2-(4',6'-difluorophenyl)pyridinate-N,C 2’ Iridium(III) picolinate (abbreviation: Firpic), bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinate-N,C 2’ Iridium(III) picolinate (abbreviation: [Ir(CF3ppy)2(pic)]), bis[2-(4',6'-difluorophenyl)pyridinate-N,C 2’Examples include organometallic iridium complexes that use phenylpyridine derivatives having electron-withdrawing groups, such as iridium(III) acetylacetonate (abbreviated as FIracac), as ligands. These compounds exhibit blue phosphorescence and have emission peaks between 440 nm and 520 nm.

[0131] Also, tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)3]), tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)3]), (acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)2(acac)]), (acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)2(acac)]), (acetylacetonato)bis[6-(2-norbornyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(nbppm)2(acac)]), (acetylacetonato)bis[5-methyl-6- Organometallic iridium complexes having a pyrimidine skeleton, such as (2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(mpmppm)2(acac)]), (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm)2(acac)]), organometallic iridium complexes having a pyrazine skeleton, such as (acetylacetonato)bis(3,5-dimethyl-2-phenylpyradinato)iridium(III) (abbreviation: [Ir(mppr-Me)2(acac)]), (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyradinato)iridium(III) (abbreviation: [Ir(mppr-iPr)2(acac)]), and tris(2-phenylpyrimidinato-N,C 2’ Iridium(III) (abbreviation: [Ir(ppy)3]), bis(2-phenylpyridinate-N,C) 2’Iridium(III) acetylacetonate (abbreviation: [Ir(ppy)2(acac)]), bis(benzo[h]quinolinate)iridium(III) acetylacetonate (abbreviation: [Ir(bzq)2(acac)]), tris(benzo[h]quinolinate)iridium(III) (abbreviation: [Ir(bzq)3]), tris(2-phenylquinolinate-N,C) 2’ Iridium(III) (abbreviation: [Ir(pq)3]), bis(2-phenylquinolinato-N,C) 2’ Examples include organometallic iridium complexes with a pyridine skeleton, such as iridium(III) acetylacetonate (abbreviated as [Ir(pq)2(acac)]), and rare earth metal complexes, such as tris(acetylacetonate)(monophenanthroline)terbium(III) (abbreviated as [Tb(acac)3(Phen)]). These compounds mainly exhibit green phosphorescence and have an emission peak between 500 nm and 600 nm. Organometallic iridium complexes with a pyrimidine skeleton are particularly preferred due to their outstanding reliability and luminescence efficiency.

[0132] Furthermore, organometallic iridium complexes having a pyrimidine skeleton, such as (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III) (abbreviation: [Ir(5mdppm)2(dibm)]), bis[4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(5mdppm)2(dpm)]), and bis[4,6-di(naphthalene-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(d1npm)2(dpm)]), Organometallic iridium complexes with a pyrazine skeleton, such as (acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: [Ir(tppr)2(acac)]), bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: [Ir(tppr)2(dpm)]), and (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: [Ir(Fdpq)2(acac)]), and tris(1-phenylisoquinolinato-N,C) 2’ Iridium(III) (abbreviation: [Ir(piq)3]), bis(1-phenylisoquinolinato-N,C) 2’ Examples include organometallic iridium complexes with a pyridine skeleton, such as iridium(III) acetylacetonate (abbreviated as [Ir(piq)2(acac)]), platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum(II) (abbreviated as PtOEP), and rare earth metal complexes such as tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III) (abbreviated as [Eu(DBM)3(Phen)]) and tris[1-(2-tenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III) (abbreviated as [Eu(TTA)3(Phen)]). These compounds exhibit red phosphorescence and have emission peaks between 600 nm and 700 nm. Furthermore, organometallic iridium complexes with a pyrazine skeleton produce a red emission with good chromaticity.

[0133] In addition to the phosphorescent compounds described above, other known phosphorescent substances may be selected and used.

[0134] As TADF materials, fullerenes and their derivatives, acridines and their derivatives, eosin derivatives, etc., can be used. Also, metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd) can be used. Examples of metal-containing porphyrins include protoporphyrin-tin fluoride complexes (SnF2(Proto IX)), mesoporphyrin-tin fluoride complexes (SnF2(Meso IX)), hematoporphyrin-tin fluoride complexes (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complexes (SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complexes (SnF2(OEP)), etioporphyrin-tin fluoride complexes (SnF2(Etio I)), and octaethylporphyrin-platinum chloride complexes (PtCl2OEP), as shown in the following structural formulas.

[0135] [ka]

[0136] Furthermore, the following structural formulas represent 2-(biphenyl-4-yl)-4,6-bis(12-phenylindoro[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviated as PIC-TRZ), 9-(4,6-diphenyl-1,3,5-triazin-2-yl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviated as PCCzTzn), 9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviated as PCCzPTzn), and 2-[4-(10H-phenoxazine-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviated as PX). Heterocyclic compounds having one or both of a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring can also be used, such as Z-TRZ, 3-[4-(5-phenyl-5,10-dihydrophenazine-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviated as PPZ-3TPT), 3-(9,9-dimethyl-9H-acridine-10-yl)-9H-xanthene-9-one (abbreviated as ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviated as DMAC-DPS), and 10-phenyl-10H,10'H-spiro[acridine-9,9'-anthracene]-10'-one (abbreviated as ACRSA). The heterocyclic compound is preferred because it has both a π-electron-excess heteroaromatic ring and a π-electron-deficient heteroaromatic ring, resulting in high electron transport and hole transport properties. Among the skeletons having a π-electron-deficient heteroaromatic ring, the pyridine skeleton, diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), and triazine skeleton are preferred because they are stable and reliable. In particular, the benzoflopyrimidine skeleton, benzothienopyrimidine skeleton, benzoflopyrazine skeleton, and benzothienopyrazine skeleton are preferred because they have high acceptor properties and are reliable. Furthermore, among the skeletons having a π-electron-excess heteroaromatic ring, the acridine skeleton, phenoxazine skeleton, phenothiazine skeleton, furan skeleton, thiophene skeleton, and pyrrole skeleton are preferred because they are stable and reliable, and therefore it is preferable to have at least one of these skeletons.Furthermore, a dibenzofuran skeleton is preferred as the furan skeleton, and a dibenzothiophene skeleton is preferred as the thiophene skeleton. In addition, as the pyrrole skeleton, indole skeleton, carbazole skeleton, indrocarbazole skeleton, bicarbazole skeleton, and 3-(9-phenyl-9H-carbazole-3-yl)-9H-carbazole skeleton are particularly preferred. Substances in which a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded are particularly preferred because both the electron-donating and electron-accepting properties of the π-electron-rich heteroaromatic ring are strengthened, and the energy difference between the S1 and T1 levels is reduced, thus efficiently obtaining thermally activated delayed fluorescence. In addition, an aromatic ring to which an electron-withdrawing group such as a cyano group is bonded may be used instead of the π-electron-deficient heteroaromatic ring. Furthermore, aromatic amine skeletons, phenazine skeletons, etc., can be used as the π-electron-rich skeleton. Furthermore, as π-electron-deficient skeletons, xanthene skeletons, thioxanthene dioxide skeletons, oxadiazole skeletons, triazole skeletons, imidazole skeletons, anthraquinone skeletons, boron-containing skeletons such as phenylborane and volanthrene, aromatic rings having a nitrile group or a cyano group such as benzonitrile or cyanobenzene, heteroaromatic rings, carbonyl skeletons such as benzophenone, phosphine oxide skeletons, sulfone skeletons, etc., can be used. In this way, π-electron-deficient skeletons and π-electron-excess skeletons can be used instead of at least one of π-electron-deficient heteroaromatic rings and π-electron-excess heteroaromatic rings.

[0137] [ka]

[0138] Furthermore, as the TADF material, a TADF material in which the singlet excited state and the triplet excited state are in thermal equilibrium may be used. Since such a TADF material has a shorter luminescence lifetime (excitation lifetime), it is possible to suppress the decrease in efficiency in the high-brightness region of the light-emitting element. Specifically, materials with the molecular structure shown below can be used.

[0139] [ka]

[0140] TADF materials are materials that have a small difference between the S1 and T1 energy levels and possess the ability to convert energy from triplet excitation energy to singlet excitation energy through reverse intersystem crossing. Therefore, triplet excitation energy can be upconverted to singlet excitation energy with only a small amount of thermal energy (reverse intersystem crossing), and singlet excited states can be efficiently generated. Furthermore, triplet excitation energy can be converted into luminescence.

[0141] Furthermore, an excited complex (also called an exciplex) that forms an excited state with two types of substances has an extremely small difference between the S1 and T1 levels and functions as a TADF material that can convert triplet excitation energy into singlet excitation energy.

[0142] Furthermore, the phosphorescence spectrum observed at low temperatures (e.g., 77K to 10K) can be used as an indicator of the T1 level. For TADF materials, when a tangent is drawn at the short-wavelength tail of the fluorescence spectrum and the energy at the wavelength of the extrapolation is taken as the S1 level, and when a tangent is drawn at the short-wavelength tail of the phosphorescence spectrum and the energy at the wavelength of the extrapolation is taken as the T1 level, it is preferable that the difference between S1 and T1 is 0.3 eV or less, and more preferably 0.2 eV or less.

[0143] Furthermore, when using TADF material as a light-emitting material, it is preferable that the S1 level of the host material is higher than the S1 level of the TADF material. Also, it is preferable that the T1 level of the host material is higher than the T1 level of the TADF material.

[0144] Various carrier transport materials can be used as the host material for the light-emitting layer, such as electron transport materials, hole transport materials, and the TADF material mentioned above.

[0145] Preferred materials with hole transport properties include organic compounds having an amine skeleton or a π-electron-rich heteroaromatic ring skeleton. For example, 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviated as NPB), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviated as TPD), 4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviated as BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviated as BPAFLP), 4-F Phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-phenyl-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBANB) Aromatic amine skeletons such as 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), and N-phenyl-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]spiro-9,9'-bifluoren-2-amine (abbreviation: PCBASF). Compounds having the carbazole skeleton, such as 1,3-bis(N-carbazolyl)benzene (abbreviated as mCP), 4,4'-di(N-carbazolyl)biphenyl (abbreviated as CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviated as CzTP), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviated as PCCP), 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviated as DBT3P-II), 2,Examples include compounds having a thiophene skeleton such as 8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviated as DBTFLP-III) and 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviated as DBTFLP-IV), and compounds having a furan skeleton such as 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviated as DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviated as mmDBFFLBi-II). Among the above, compounds having an aromatic amine skeleton and compounds having a carbazole skeleton are preferred because they have good reliability, high hole transportability, and contribute to reducing the driving voltage. Organic compounds listed as examples of the first substance above can also be used.

[0146] Preferred materials with electron transport properties include metal complexes such as bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviated as BeBq2), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (abbreviated as BAlq), bis(8-quinolinolato)zinc(II) (abbreviated as Znq), bis[2-(2-benzoxazollyl)phenolato]zinc(II) (abbreviated as ZnPBO), and bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviated as ZnBTZ), as well as organic compounds having a π-electron-deficient heteroaromatic ring skeleton. Examples of organic compounds having a π-electron-deficient heteroaromatic ring skeleton include 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviated as PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviated as TAZ), and 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazole (abbreviated as TAZ). [Diazole-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazole-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-be Heterocyclic compounds having a polyazole skeleton such as nzoimidazole (abbreviation: mDBTBIm-II), 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- Heterocyclic compounds having a diazine skeleton, such as carbazole-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 4,6-bis[3-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), and 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), and 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)-1,1'-biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn), 2-[(1,1'-biphenyl)-4-yl]-4-phenyl-6-[9,9'-spirobi(9H-fluoren)-2-yl]-1,3,5-triazine (abbreviation: BP-SFTzn), 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-8-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: m Examples include heterocyclic compounds having a triazine skeleton, such as BnfBPTzn, 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-6-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviated as mBnfBPTzn-02), and heterocyclic compounds having a pyridine skeleton, such as 3,5-bis[3-(9H-carbazole-9-yl)phenyl]pyridine (abbreviated as 35DCzPPy) and 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviated as TmPyPB). Among the above, heterocyclic compounds having a diazine skeleton, heterocyclic compounds having a triazine skeleton, and heterocyclic compounds having a pyridine skeleton are preferred due to their good reliability. In particular, heterocyclic compounds having a diazine (pyrimidine, pyrazine, etc.) skeleton have high electron transport properties and contribute to reducing the driving voltage.

[0147] The TADF materials listed above can be used as host materials. When a TADF material is used as a host material, the triplet excitation energy generated by the TADF material is converted into singlet excitation energy through reverse intersystem crossing, and this energy is then transferred to the light-emitting material, thereby increasing the luminescence efficiency of the light-emitting device. In this case, the TADF material functions as an energy donor, and the light-emitting material functions as an energy acceptor.

[0148] This is particularly effective when the light-emitting material is a fluorescent material. Furthermore, in order to obtain high luminescence efficiency, it is preferable that the S1 level of the TADF material is higher than that of the fluorescent material. Also, it is preferable that the T1 level of the TADF material is higher than that of the fluorescent material. Therefore, it is preferable that the T1 level of the TADF material is higher than that of the fluorescent material.

[0149] Furthermore, it is preferable to use a TADF material that exhibits emission that overlaps with the wavelength of the lowest-energy absorption band of the fluorescent material. This is preferable because it allows for smooth transfer of excitation energy from the TADF material to the fluorescent material, resulting in efficient emission.

[0150] Furthermore, for singlet excitation energy to be efficiently generated from triplet excitation energy by 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 achieve this, it is preferable that the fluorescent material has protecting groups around the luminescent phosphodiocyte (the skeleton that causes luminescence). Preferred protecting groups are substituents without π bonds, and saturated hydrocarbons are preferred. Specifically, 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 preferable to have multiple protecting groups. Substituents without π bonds have poor carrier transport function, and therefore can increase the distance between the TADF material and the luminescent phosphodiocyte of the fluorescent material with little effect on carrier transport and carrier recombination. Here, the luminescent phosphodiocyte refers to the atomic group (skeleton) that causes luminescence in the fluorescent material. The luminescent phosphodiosity preferably has a skeleton containing π bonds, preferably contains an aromatic ring, and preferably has a condensed aromatic ring or a condensed heteroaromatic ring. Examples of condensed aromatic rings or condensed heteroaromatic rings include phenanthrene skeletons, stilbene skeletons, acridone skeletons, phenoxazine skeletons, and phenothiazine skeletons. Fluorescent materials having naphthalene, anthracene, fluorene, chrysene, triphenylene, tetracene, pyrene, perylene, coumarin, quinacridone, or naphthobisbenzofuran skeletons are particularly preferred due to their high fluorescence quantum yield.

[0151] When using a fluorescent material as the light-emitting material, a material having an anthracene skeleton is preferred as the host material. Using a material having an anthracene skeleton as the host material for a fluorescent material makes it possible to realize a light-emitting layer with good luminescence efficiency and durability. Among the materials having an anthracene skeleton to be used as the host material, materials having a diphenylanthracene skeleton, and especially a 9,10-diphenylanthracene skeleton, are preferred because they are chemically stable. Furthermore, while a carbazole skeleton is preferred as the host material because it improves hole injection and transport, a benzocarbazole skeleton, in which a benzene ring is further condensed into carbazole, is even more preferred because the HOMO is about 0.1 eV shallower than carbazole, making it easier for holes to enter. In particular, a dibenzocarbazole skeleton is preferred as the HOMO is about 0.1 eV shallower than 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 that simultaneously possesses a 9,10-diphenylanthracene skeleton and a carbazole skeleton (or a benzocarbazole skeleton, or a dibenzocarbazole skeleton). Furthermore, from the viewpoint of hole injection and transport properties, 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 (abbreviated as PCzPA), 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviated as PCPN), 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviated as CzPA), and 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole. Examples include ruvasol (abbreviated as cgDBCzPA), 6-[3-(9,10-diphenyl-2-anthryl)phenyl]-benzo[b]naphtho[1,2-d]furan (abbreviated as 2mBnfPPA), 9-phenyl-10-{4-(9-phenyl-9H-fluoren-9-yl)biphenyl-4'-yl}anthracene (abbreviated as FLPPA), and 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviated as αN-βNPAnth).In particular, CzPA, cgDBCzPA2mBnfPPA, and PCzPA exhibit very good properties and are therefore preferred choices.

[0152] The host material may be a mixture of multiple substances, and when using a mixed host material, it is preferable to mix an electron-transporting material with a hole-transporting material. By mixing an electron-transporting material with a hole-transporting material, 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 hole-transporting material to the electron-transporting material should be 1:19 to 19:1.

[0153] Furthermore, phosphorescent materials can be used as part of the above-mentioned mixed materials. When a fluorescent material is used as the light-emitting material, the phosphorescent material can be used as an energy donor to supply excitation energy to the fluorescent material.

[0154] Furthermore, these mixed materials may form an excited complex. It is preferable to select a combination that forms an excited complex that exhibits emission overlapping with the wavelength of the lowest-energy absorption band of the luminescent material, as this facilitates smooth energy transfer and efficiently obtains light emission. This configuration is also preferable because it reduces the driving voltage.

[0155] Furthermore, at least one of the materials forming the excitation complex may be a phosphorescent material. By doing so, the triplet excitation energy can be efficiently converted to singlet excitation energy through reverse intersystem crossing.

[0156] For efficient excitation complex formation, it is preferable that the HOMO level of the hole-transporting material is above the HOMO level of the electron-transporting material. Furthermore, it is preferable that the LUMO level of the hole-transporting material is above the LUMO level of the electron-transporting material. The LUMO and HOMO levels of the materials can be derived from the electrochemical properties (reduction potential and oxidation potential) of the materials measured by cyclic voltammetry (CV).

[0157] The formation of excited complexes can be confirmed, for example, by comparing the emission spectra of a hole-transporting material, an electron-transporting material, and a mixed film made by mixing these materials, and observing that the emission spectrum of the mixed film shifts to a longer wavelength than the emission spectra of each individual material (or has a new peak on the longer wavelength side). Alternatively, it can be confirmed by comparing the transient photoluminescence (PL) of a hole-transporting material, the transient PL of an electron-transporting material, and the transient PL of a mixed film made by mixing these materials, and observing differences in the transient response, such as the transient PL lifetime of the mixed film having a longer lifetime component or a larger proportion of the delayed component than the transient PL lifetime of each individual material. Furthermore, the transient PL mentioned above can be replaced with transient electroluminescence (EL). That is, the formation of excited complexes can also be confirmed by comparing the transient EL of a hole-transporting material, the transient EL of an electron-transporting material, and the transient EL of a mixed film made by mixing these materials, and observing the differences in the transient response.

[0158] The electron transport layer 114 is a layer containing an electron-transporting material. As the electron-transporting material, any of the electron-transporting materials listed above that can be used in the host material can be used. If a material with a large GSP_slope is used for the electron transport layer 114, a material with a GSP_slope of 20 (mV / nm) or higher should be selected from among them.

[0159] Furthermore, it is preferable that the material forming the electron transport layer has at least three C2 to C5 chain alkyl groups or C6 to C12 cycloalkyl groups, particularly C3 to C5 branched chain alkyl groups, as this can lower the refractive index of the hole transport layer 112 and improve the light extraction efficiency. Examples of such materials include 2-{(3',5'-di-tert-butyl)-1,1'-biphenyl-3-yl}-4,6-bis(3,5-di-tert-butylphenyl)-1,3,5-triazine (abbreviation: mmtBumBP-dmmtBuPTzn), 2-{(3',5'-di-tert-butyl)-1,1'-biphenyl-3-yl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mmtBumBPTzn), and 2-(3,3'',5,5''-te Tra-tert-butyl-1,1':3',1''-terphenyl-5'-yl)-4,6-diphenyl-1,3,5-triazine (abbreviation: mmtBumTPTzn), 2-(3',5'-di-tert-butylbiphenyl-3-yl)-4,6-bis(3,5-di-tert-butylphenyl)pyrimidine (abbreviation: mmtBumBP-dmmtBuPPm), 2-(3,3'',5',5''-tetra-tert-butyl-1,1':3',1''-terphenyl-5- (Iyl)-4,6-diphenyl-1,3,5-triazine (abbreviation: mmtBumTPTzn-02), 2-{3-(3,5-dicyclohexylphenyl)phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mmchmBPTzn), 2-(3'',5',5''-tri-tert-butyl-1,1':3',1''-terphenyl-4-yl)-4,6-diphenyl-1,3,5-triazine (abbreviation: mmtBumTPTzn-04), 2-[3-(2, 6-dimethylpyridine-3-yl)-5-{(3,5-di-tert-butyl)phenyl}phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mmtBuPh-mDMePyPTzn), 2-(3'',5',5''-tri-tert-butyl-1,1':3',1''-terphenyl-5-yl)-4,6-diphenyl-1,3,5-triazine (abbreviation: mmtBumTPTzn-03), 2,4-bis[(3',5'-di-tert-butyl)-1,1'-biphenyl-3-yl]-6-phenyl-1,3,5-triazine (abbreviation: mmtBumBP2Tzn), 2-{(1,1'-biphenyl)-2-yl}-4-{(3',5'-di-tert-butyl)-1,1'-biphenyl-3-yl}-6-phenyl-1,3,5-triazine (abbreviation: oBP-mmtBumBPTzn), 2-[(1,1'-biphenyl)-2-yl]-4-{(3',5'-di-tert-butyl)-1,1'-biphenyl-4-yl}-6-phenyl-1,3,5-triazine (abbreviation: o BP-mmtBuBPTzn), 2-[3-{(3,5-di-tert-butyl)phenyl}-5-(3-pyridyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mmtBuPh-mPyPTzn), 2-[3-(2,6-dimethylpyridine-3-yl)-5-{3',5,5'-tri-tert-butylbiphenyl}phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mmtBuBP-mDMePyPTzn), 2-[3-(2,6-dimethylpyridine-3-yl)-5-{(3' ,5'-di-tert-butyl)-1,1'-biphenyl-3-yl}phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mmtBuBP-mDMePyPTzn-02), 2,4-[(1,1'-biphenyl)-2-yl]-6-[3-(2,6-dimethylpyridine-3-yl)-5-{(3,5-di-tert-butyl)phenyl}]phenyl-1,3,5-triazine (abbreviation: oBP2-mmtBuPh-mDMePyPTzn), 2-[(1,1'-biphenyl)-2-yl]-4-[3-(2, 6-dimethylpyridine-3-yl)-5-{(3,5-di-tert-butyl)phenyl}]phenyl-6-phenyl-1,3,5-triazine (abbreviation: oBP-mmtBuPh-mDMePyPTzn), 2,4,6-tris{3'-(pyridine-3-yl)-5'-tert-butyl-1,1'-biphenyl-3-yl}-1,3,5-triazine (abbreviation: tBu-TmPPPyTz) and 2,4,6-tris{3'-(pyridine-3-yl)-5'-tert-butyl-1,1'-biphenyl-4-yl}-1,3,Examples include 5-triazine (abbreviation: tBu-TmPPPyTz-02). Layers containing materials with large GSP_slope can be formed using materials with a GSP_slope of 20 (mV / nm) or higher from among these options.

[0160] Furthermore, the electron transport layer preferably contains an electron-transporting material and an alkali metal or alkaline earth metal in elemental form, compound, or complex form. In addition, the electron transport layer 114 has an electron mobility of 1 × 10 at an electric field strength [V / cm] square root of 600. -7 cm 2 / Vs or more 5×10 -5 cm 2It is preferable that the value is less than or equal to / Vs. By reducing the electron transport properties in the electron transport layer 114, the amount of electrons injected into the light-emitting layer can be controlled, and it is possible to prevent the light-emitting layer from becoming electron-excessive. This configuration is particularly preferable because it results in a good lifetime when the hole injection layer is formed as a composite material and the HOMO level of the material having hole transport properties in the composite material is a relatively deep HOMO level between -5.7eV and -5.4eV. In this case, it is preferable that the HOMO level of the material having electron transport properties is -6.0eV or higher. Furthermore, it is preferable that the material having electron transport properties is an organic compound having an anthracene skeleton, and more preferably an organic compound containing both an anthracene skeleton and a heterocyclic skeleton. The heterocyclic skeleton is preferably a nitrogen-containing five-membered ring skeleton or a nitrogen-containing six-membered ring skeleton. These heterocyclic skeletons are particularly preferably nitrogen-containing five-membered ring skeletons or nitrogen-containing six-membered ring skeletons that contain two heteroatoms in the ring, such as pyrazole rings, imidazole rings, oxazole rings, thiazole rings, pyrazine rings, pyrimidine rings, and pyridazine rings. Furthermore, the alkali metal or alkali metal element, compound, or complex preferably contains an 8-hydroxyquinolinate structure. Specifically, examples include 8-hydroxyquinolinate-lithium (abbreviated as Liq) and 8-hydroxyquinolinate-sodium (abbreviated as Naq). In particular, complexes of monovalent metal ions, especially lithium complexes, are preferred, with Liq being more preferred. When an 8-hydroxyquinolinate structure is included, its methyl-substituted derivatives (e.g., 2-methyl-substituted derivatives or 5-methyl-substituted derivatives) can also be used. Furthermore, it is preferable that alkali metals or alkali metal elements, compounds, or complexes exist in the electron transport layer with a concentration difference (including cases where the concentration is zero) in the thickness direction.

[0161] Between the electron transport layer 114 and the second electrode 102, an electron injection layer 115 may be provided, containing an alkali metal or alkaline earth metal or a compound thereof, such as lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF2), or 8-hydroxyquinolinatolithium (abbreviated as Liq). The electron injection layer 115 may be a layer made of an electron-transporting material containing an alkali metal or alkaline earth metal or a compound thereof, or an electride may be used. Examples of electrides include a substance obtained by adding electrons to a mixed oxide of calcium and aluminum at a high concentration.

[0162] Furthermore, as the electron injection layer 115, it is also possible to use a layer containing an electron-transporting substance (preferably an organic compound having a bipyridine skeleton) with an alkali metal or alkaline earth metal fluoride at a concentration above that which results in a microcrystalline state (50 wt% or more). Since this layer has a low refractive index, it is possible to provide a light-emitting device with better external quantum efficiency.

[0163] Alternatively, a charge generation layer 116 may be provided instead of the electron injection layer 115 (Figure 3(B)). The charge generation layer 116 is a layer that can inject holes into the layer in contact with the cathode side and electrons into the layer in contact with the anode side by applying a potential. The charge generation layer 116 includes at least a P-type layer 117. The P-type layer 117 is preferably formed using a composite material listed above as a material that can constitute the hole injection layer 111. The P-type layer 117 may also be formed by laminating a film containing the acceptor material and a film containing the hole transport material as materials constituting the composite material. By applying a potential to the P-type layer 117, electrons are injected into the electron transport layer 114 and holes into the second electrode 102, and the light-emitting device operates. Furthermore, since the organic compound in one embodiment of the present invention is an organic compound with a low refractive index, by using it in the P-type layer 117, a light-emitting device with good external quantum efficiency can be obtained.

[0164] Furthermore, it is preferable that the charge generation layer 116 includes, in addition to the P-type layer 117, one or both of the electron relay layer 118 and the electron injection buffer layer 119.

[0165] The electron relay layer 118 contains at least an electron-transporting material and has the function of preventing interaction between the electron injection buffer layer 119 and the P-type layer 117, thereby smoothly transferring electrons. The LUMO level of the electron-transporting material contained in the electron relay layer 118 is preferably between the LUMO level of the acceptor material in the P-type layer 117 and the LUMO level of the material contained in the layer in contact with the charge generation layer 116 in the electron transport layer 114. The specific energy level of the LUMO level of the electron-transporting material used in the electron relay layer 118 is preferably -5.0 eV or higher, more preferably -5.0 eV or higher and -3.0 eV or lower. It is preferable to use a phthalocyanine-based material or a metal complex having a metal-oxygen bond and an aromatic ligand as the electron-transporting material used in the electron relay layer 118.

[0166] The electron injection buffer layer 119 can use materials with high electron injection potential, such as alkali metals, alkaline earth metals, rare earth metals, and compounds thereof (alkali metal compounds (including oxides such as lithium oxide, halides, and carbonates such as lithium carbonate and cesium carbonate), alkaline earth metal compounds (including oxides, halides, and carbonates), or rare earth metal compounds (including oxides, halides, and carbonates)).

[0167] Furthermore, if the electron injection buffer layer 119 is formed by including an electron-transporting substance and a donor substance, the donor substance can 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), or rare earth metal compounds (including oxides, halides, and carbonates)), as well as organic compounds such as tetratianaphthalene (abbreviated as TTN), nickerosene, and decamethylnickerosene. The electron-transporting substance can be formed using the same materials as those used to constitute the electron transport layer 114 described above.

[0168] As the material forming the second electrode 102, metals, alloys, electrically conductive compounds, and mixtures thereof with a small work function (specifically, 3.8 eV or less) can be used. Specific examples of such cathode materials include alkali metals such as lithium (Li) and cesium (Cs), elements belonging to Group 1 or 2 of the periodic table such as magnesium (Mg), calcium (Ca), and strontium (Sr), and 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, silicon, or indium oxide-tin oxide containing silicon oxide can be used as the second electrode 102, regardless of the magnitude of the work function. These conductive materials can be deposited using dry methods such as vacuum deposition and sputtering, inkjet methods, and spin coating methods. Alternatively, the material may be formed using a wet process with a sol-gel method, or it may be formed using a wet process with a paste of a metallic material.

[0169] Furthermore, various methods can be used to form the EL layer 103, regardless of whether they are dry or wet methods. For example, vacuum deposition, gravure printing, offset printing, screen printing, inkjet printing, or spin coating may be used.

[0170] Furthermore, each electrode or layer described above may be formed using different film deposition methods.

[0171] The configuration of the layer provided between the first electrode 101 and the second electrode 102 is not limited to those described above. However, a configuration is preferred in which a light-emitting region is provided at a location away from the first electrode 101 and the second electrode 102 where holes and electrons recombine, in order to suppress quenching that occurs when the light-emitting region is in close proximity to the electrode or the metal used in the carrier injection layer.

[0172] Furthermore, the hole transport layer and electron transport layer in contact with the light-emitting layer 113, and especially the carrier transport layer near the recombination region in the light-emitting layer 113, are preferably composed of a material whose band gap is larger than that 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.

[0173] Next, an embodiment of a light-emitting device (also called a stacked element or tandem element) with a configuration in which multiple light-emitting units are stacked will be described with reference to Figure 3(C). This light-emitting device has multiple light-emitting units between the anode and the cathode. Each light-emitting unit has a configuration almost identical to the EL layer 103 shown in Figure 3(A). In other words, the light-emitting device shown in Figure 3(C) is a light-emitting device with multiple light-emitting units, while the light-emitting device shown in Figure 3(A) or Figure 3(B) is a light-emitting device with one light-emitting unit.

[0174] In Figure 3(C), a first light-emitting unit 511 and a second light-emitting unit 512 are stacked between the first electrode 501 and the second electrode 502, and a charge generation layer 513 is provided between the first light-emitting unit 511 and the second light-emitting unit 512. The first electrode 501 and the second electrode 502 correspond to the first electrode 101 and the second electrode 102 in Figure 3(A), respectively, and the same components described in the explanation of Figure 3(A) can be applied. Furthermore, the first light-emitting unit 511 and the second light-emitting unit 512 may have the same configuration or different configurations. It is preferable that a layer containing a material with a large GSP_slope be provided in either or all of the hole transport layer and electron transport layer of the first light-emitting unit 511 and the second light-emitting unit 512.

[0175] The charge generation layer 513 has the function of injecting electrons into one light-emitting unit and holes into the other light-emitting unit when a voltage is applied to the first electrode 501 and the second electrode 502. That is, in Figure 3(C), when a voltage is applied such that the potential of the anode is higher than the potential of the cathode, the charge generation layer 513 only needs to inject electrons into the first light-emitting unit 511 and holes into the second light-emitting unit 512.

[0176] The charge generation layer 513 is preferably formed with the same configuration as the charge generation layer 116 described in Figure 3(B). The composite material of organic compound and metal oxide has excellent carrier implantation and carrier transport properties, enabling low-voltage and low-current operation. If the anode side of the light-emitting unit is in contact with the charge generation layer 513, the charge generation layer 513 can also act as a hole injection layer for the light-emitting unit, so the light-emitting unit does not need to have a hole injection layer.

[0177] Furthermore, when an electron injection buffer layer 119 is provided in the charge generation layer 513, the electron injection buffer layer 119 plays the role of an electron injection layer in the anode-side light-emitting unit, so it is not necessarily required to form an electron injection layer in the anode-side light-emitting unit.

[0178] Figure 3(C) illustrates a light-emitting device having two light-emitting units, but the same principles can be applied to light-emitting devices with three or more stacked light-emitting units. As in the light-emitting device according to this embodiment, by arranging multiple light-emitting units separated between a pair of electrodes by a charge generation layer 513, high-brightness light emission can be achieved while maintaining a low current density, and a long-life element can be realized. Furthermore, a light-emitting device that can be driven at a low voltage and consumes little power can be realized.

[0179] Furthermore, by making the light-emitting colors of each light-emitting unit different, it is possible to obtain a desired color of light emission from the entire light-emitting device. For example, in a light-emitting device having two light-emitting units, it is possible to obtain a light-emitting device that emits white light as a whole by obtaining red and green light-emitting colors from the first light-emitting unit and blue light-emitting color from the second light-emitting unit.

[0180] Furthermore, each layer, such as the EL layer 103, the first light-emitting unit 511, the second light-emitting unit 512, and the charge generation layer, as well as the electrodes, can be formed using methods such as vapor deposition (including vacuum deposition), droplet ejection (also known as inkjet printing), coating, and gravure printing. They may also contain low-molecular-weight materials, medium-molecular-weight materials (including oligomers and dendrimers), or polymer materials.

[0181] (Embodiment 3) This embodiment describes a light-emitting device using the light-emitting devices described in Embodiment 1 and Embodiment 2.

[0182] In this embodiment, a light-emitting device manufactured using the light-emitting devices described in Embodiment 1 and Embodiment 2 will be described with reference to Figure 38. Figure 38(A) is a top view showing the light-emitting device, and Figure 38(B) is a cross-sectional view obtained by cutting Figure 38(A) along A and C. This light-emitting device includes a drive circuit section (source line drive circuit) 601, a pixel section 602, and a drive circuit section (gate line drive circuit) 603, all indicated by dotted lines, to control the light emission of the light-emitting device. Furthermore, 604 is a sealing substrate, and 605 is a sealing material, with the area enclosed by the sealing material 605 being a space 607.

[0183] The routing wiring 608 is for transmitting signals input to the source line drive circuit 601 and the gate line drive circuit 603, and receives video signals, clock signals, start signals, reset signals, etc. from the FPC (flexible printed circuit) 609, which serves as an external input terminal. Although only the FPC is shown in this illustration, a printed circuit 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 the state in which the FPC or PWB is attached to it.

[0184] Next, the cross-sectional structure will be explained using Figure 38(B). A drive circuit section and a pixel section are formed on the element substrate 610, and here, the source line drive circuit 601, which is the drive circuit section, and one pixel in the pixel section 602 are shown.

[0185] The element substrate 610 may be manufactured using a substrate made of glass, quartz, organic resin, metal, alloy, semiconductor, or other materials, as well as a plastic substrate made of FRP (Fiber Reinforced Plastics), PVF (Polyvinyl Fluoride), polyester, or acrylic resin.

[0186] The structure of the transistors used in the pixels and driving circuits is not particularly limited. For example, they may be inverse staggered transistors or staggered transistors. They may also be top-gate or bottom-gate transistors. The semiconductor material used for the transistors is not particularly limited; for example, silicon, germanium, silicon carbide, gallium nitride, etc., can be used. Alternatively, an oxide semiconductor containing at least one of indium, gallium, and zinc, such as an In-Ga-Zn metal oxide, may be used.

[0187] The crystallinity of the semiconductor material used in the transistor is not particularly limited; amorphous semiconductors, crystalline semiconductors (microcrystalline semiconductors, polycrystalline semiconductors, single-crystal semiconductors, or semiconductors having a crystalline region in part) may be used. Using a crystalline semiconductor is preferable because it can suppress the degradation of transistor characteristics.

[0188] Here, it is preferable to use oxide semiconductors for semiconductor devices such as transistors used in the pixels and driving circuits described above, as well as transistors used in touch sensors and the like, which will be described later. In particular, it is preferable to use oxide semiconductors with a wider bandgap than silicon. By using oxide semiconductors with a wider bandgap than silicon, the current in the off state of the transistor can be reduced.

[0189] The above oxide semiconductor preferably contains at least indium (In) or zinc (Zn). More preferably, it is an oxide semiconductor containing an oxide represented as an In-M-Zn oxide (where M is a metal such as Al, Ti, Ga, Ge, Y, Zr, Sn, La, Ce, or Hf).

[0190] In particular, it is preferable to use an oxide semiconductor film as the semiconductor layer, which has multiple crystalline portions, the c-axis of which is oriented perpendicular to the surface on which the semiconductor layer is formed or to the upper surface of the semiconductor layer, and which does not have grain boundaries between adjacent crystalline portions.

[0191] By using such materials as semiconductor layers, fluctuations in electrical properties can be suppressed, enabling the realization of highly reliable transistors.

[0192] Furthermore, due to its low off-current, the transistor having the aforementioned semiconductor layer can retain the charge stored in the capacitor via the transistor for a long period of time. By applying such transistors to pixels, it becomes possible to maintain the gradation of the image displayed in each display area while simultaneously stopping the drive circuit. As a result, electronic devices with extremely reduced power consumption can be realized.

[0193] It is preferable to provide an undercoat to stabilize the characteristics of the transistor. As the undercoat, an inorganic insulating film such as a silicon oxide film, silicon nitride film, silicon oxynitride film, or silicon nitride film can be used and fabricated as a single layer or in layers. The undercoat can be formed using sputtering, CVD (Chemical Vapor Deposition) (plasma CVD, thermal CVD, MOCVD (Metal Organic CVD), etc.), ALD (Atomic Layer Deposition), coating, printing, etc. Note that the undercoat may be omitted if not necessary.

[0194] Note that FET623 is one of the transistors formed in the drive circuit section 601. The drive circuit can be formed using various CMOS, PMOS, or NMOS circuits. In this embodiment, a driver-integrated type with the drive circuit formed on the substrate is shown, but this is not necessarily required, and the drive circuit can be formed externally instead of on the substrate.

[0195] Furthermore, although the pixel section 602 is formed by a plurality of pixels including a switching FET 611 and a current control FET 612 and a first electrode 613 electrically connected to its drain, it is not limited to this, and the pixel section may be a combination of three or more FETs and a capacitive element.

[0196] Furthermore, an insulator 614 is formed to cover the end of the first electrode 613. This can be formed by using a positive-type photosensitive acrylic resin film.

[0197] Furthermore, in order to ensure good coverage of the EL layer and the like that will be formed later, a curved surface with curvature is formed at the upper or lower end of the insulator 614. For example, when a positive-type photosensitive acrylic resin is used as the material for the insulator 614, it is preferable to have a curved surface with a radius of curvature (0.2 μm to 3 μm) only at the upper end of the insulator 614. In addition, either a negative-type photosensitive resin or a positive-type photosensitive resin can be used as the insulator 614.

[0198] An EL layer 616 and a second electrode 617 are formed on the first electrode 613, respectively. Here, it is desirable to use a material with a large work function for the first electrode 613 which functions as an anode. For example, in addition to single-layer films such as ITO film, silicon-containing indium tin oxide film, indium oxide film containing 2-20 wt% zinc oxide, titanium nitride film, chromium film, tungsten film, Zn film, and Pt film, a laminate of titanium nitride film and a film mainly composed of aluminum, or a three-layer structure of titanium nitride film, a film mainly composed of aluminum, and titanium nitride film can be used. Furthermore, a laminated structure has low resistance as wiring, good ohmic contact can be obtained, and it can function as an anode.

[0199] Furthermore, the EL layer 616 is formed by various methods such as vapor deposition using a vapor deposition mask, inkjet printing, and spin coating. The EL layer 616 includes the configuration described in Embodiment 1 and Embodiment 2. Other materials constituting the EL layer 616 may be low molecular weight compounds or high molecular weight compounds (including oligomers and dendrimers).

[0200] Furthermore, it is preferable to use a material with a low work function (such as Al, Mg, Li, Ca, or alloys and compounds thereof (MgAg, MgIn, AlLi, etc.)) for the second electrode 617, which is formed on the EL layer 616 and functions as a cathode. When light generated in the EL layer 616 is transmitted through the second electrode 617, it is preferable to use a laminate of a thin metal film and a transparent conductive film (such as ITO, indium oxide containing 2-20 wt% zinc oxide, indium tin oxide containing silicon, or zinc oxide (ZnO)) as the second electrode 617.

[0201] The first electrode 613, the EL layer 616, and the second electrode 617 form a light-emitting device. This light-emitting device is the light-emitting device described in Embodiment 1 and Embodiment 2. Although the pixel portion is made up of multiple light-emitting devices, the light-emitting device in this embodiment may contain a mixture of the light-emitting devices described in Embodiment 1 and Embodiment 2 and light-emitting devices having other configurations.

[0202] Furthermore, by bonding the sealing substrate 604 to the element substrate 610 with the sealing material 605, the light-emitting device 618 is provided in the 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 material, which may be an inert gas (nitrogen, argon, etc.) or a sealing material. A recess is formed in the sealing substrate, and a desiccant is placed therein to suppress deterioration due to the effects of moisture, which is a preferred configuration.

[0203] Furthermore, it is preferable to use epoxy resin or glass frit for the sealing material 605. It is also desirable that these materials are as impermeable to moisture and oxygen as possible. In addition to glass substrates and quartz substrates, plastic substrates made of FRP (Fiber Reinforced Plastics), PVF (Polyvinyl Fluoride), polyester, or acrylic resin can be used as the material for the sealing substrate 604.

[0204] Although not shown in Figure 38, a protective film may be provided on the second electrode. The protective film may be made of an organic resin film or an inorganic insulating film. Alternatively, the protective film may be formed to cover the exposed portion of the sealing material 605. Furthermore, the protective film can be provided to cover the surface and sides of the pair of substrates, the sealing layer, the insulating layer, and other exposed sides.

[0205] The protective film can be made of a material that is impermeable to impurities such as water. Therefore, it is possible to effectively suppress the diffusion of impurities such as water from the outside to the inside.

[0206] Materials that constitute the protective film can include oxides, nitrides, fluorides, sulfides, ternary compounds, metals, or polymers. For example, materials 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, or indium oxide can be used. Materials containing aluminum nitride, hafnium nitride, silicon nitride, tantalum nitride, titanium nitride, niobium nitride, molybdenum nitride, zirconium nitride, or gallium nitride can be used. Nitrides containing titanium and aluminum, oxides containing titanium and aluminum, oxides containing aluminum and zinc, sulfides containing manganese and zinc, sulfides containing cerium and strontium, oxides containing erbium and aluminum, oxides containing yttrium and zirconium can be used.

[0207] It is preferable to form the protective film using a film deposition method that provides good step coverage. One such method is atomic layer deposition (ALD). It is preferable to use a material that can be formed using the ALD method for the protective film. By using the ALD method, it is possible to form a dense protective film with reduced defects such as cracks and pinholes, or a protective film with a uniform thickness. Furthermore, it is possible to reduce the damage inflicted on the processed workpiece when forming the protective film.

[0208] For example, by forming a protective film using the ALD method, a uniform and defect-free protective film can be formed on surfaces with complex uneven shapes, including the top, sides, and back of a touch panel.

[0209] As described above, a light-emitting device can be obtained using the light-emitting devices described in Embodiment 1 and Embodiment 2.

[0210] Since the light-emitting device in this embodiment uses the light-emitting devices described in Embodiment 1 and Embodiment 2, a light-emitting device with good characteristics can be obtained. Specifically, because the light-emitting devices described in Embodiment 1 and Embodiment 2 have a low driving voltage, it is possible to make a light-emitting device with low power consumption.

[0211] Figure 39 shows an example of a light-emitting device that is made full-color by forming a light-emitting device that emits white light and providing a colored layer (color filter), etc. Figure 39(A) shows a substrate 1001, a base insulating film 1002, a gate insulating film 1003, gate electrodes 1006, 1007, 1008, a first interlayer insulating film 1020, a second interlayer insulating film 1021, a peripheral portion 1042, a pixel portion 1040, a drive circuit portion 1041, first electrodes 1024W, 1024R, 1024G, 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 sealing material 1032, etc.

[0212] In Figure 39(A), the colored layers (red colored layer 1034R, green colored layer 1034G, and blue colored layer 1034B) are provided on a transparent substrate 1033. A black matrix 1035 may also be provided. The transparent substrate 1033 on which the colored layers and black matrix are provided is aligned and fixed to the substrate 1001. The colored layers and black matrix 1035 are covered with an overcoat layer 1036. In Figure 39(A), there is an emissive layer that emits light to the outside without passing through the colored layers, and an emissive layer that emits light to the outside by passing through each colored layer. Light that does not pass through the colored layers is white, and light that passes through the colored layers is red, green, and blue, so an image can be represented with four colored pixels.

[0213] Figure 39(B) shows an example in which colored layers (red colored layer 1034R, green colored layer 1034G, and blue colored layer 1034B) are formed between the gate insulating film 1003 and the first interlayer insulating film 1020. Thus, the colored layers may also be provided between the substrate 1001 and the encapsulating substrate 1031.

[0214] Furthermore, although the light-emitting device described above is a bottom-emission type device that extracts light from the substrate 1001 on which the FET is formed, it may also be a top-emission type device that extracts light from the sealing substrate 1031. A cross-sectional view of the top-emission type light-emitting device is shown in Figure 40. In this case, the substrate 1001 can be a substrate that does not transmit light. The process is the same as for the bottom-emission type light-emitting device until the connecting electrode that connects the FET and the anode of the light-emitting device is fabricated. After that, a third interlayer insulating film 1037 is formed covering the electrode 1022. This insulating film may also play a planarization role. 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.

[0215] The first electrodes 1024W, 1024R, 1024G, and 1024B of the light-emitting device are designated as anodes here, but they may also be cathodes. Furthermore, in the case of a top-emission type light-emitting device as shown in Figure 40, it is preferable that the first electrodes be reflective electrodes. The configuration of the EL layer 1028 is the same as that described as the EL layer 103 in Embodiments 1 and 2, and the element structure is such that white light emission can be obtained.

[0216] In a top-emission structure as shown in Figure 40, sealing can be performed with a sealing substrate 1031 having colored layers (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B). A black matrix 1035 may also be provided on the sealing substrate 1031 so as to be located between pixels. The colored layers (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B) and the black matrix may be covered with an overcoat layer 1036. The sealing substrate 1031 should be a translucent substrate. In addition, although an example of full-color display using four colors, red, green, blue, and white, is shown here, it is not particularly limited, and full-color display may also be performed using four colors, red, yellow, green, and blue, or three colors, red, green, and blue.

[0217] In top-emission type light-emitting devices, a microcavity structure can be suitably applied. A light-emitting device having a microcavity structure is obtained by using a reflective electrode as the first electrode and a semi-transparent / semi-reflective electrode as the second electrode. There is at least an EL layer between the reflective electrode and the semi-transparent / semi-reflective electrode, and there is at least a light-emitting layer that forms a light-emitting region.

[0218] The reflective electrode has a visible light reflectance of 40% to 100%, preferably 70% to 100%, and its resistivity is 1 × 10⁻⁶. -2 The film thickness is assumed to be Ωcm or less. Furthermore, the semi-transparent / semi-reflective electrode has a visible light reflectance of 20% to 80%, preferably 40% to 70%, and its resistivity is 1 × 10⁻⁶. -2 Assume the membrane is less than Ωcm in diameter.

[0219] The light emitted from the light-emitting layer contained in the EL layer is reflected and resonated by the reflective electrode and the semi-transmissive / semi-reflective electrode.

[0220] By changing the thicknesses of the transparent conductive film, the above composite material, the carrier transport material, etc., the optical distance between the reflective electrode and the semi-transmissive / semi-reflective electrode can be changed in this light-emitting device. Thereby, between the reflective electrode and the semi-transmissive / semi-reflective electrode, the light of the resonant wavelength can be enhanced and the light of the non-resonant wavelength can be attenuated.

[0221] In addition, since the light (the first reflected light) reflected by the reflective electrode and returned causes significant interference with the light directly incident from the light-emitting layer to the semi-transmissive / semi-reflective electrode (the first incident light), 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 to be amplified). By adjusting the optical distance, the phases of the first reflected light and the first incident light can be matched to further amplify the light emitted from the light-emitting layer.

[0222] In the above configuration, the EL layer may have a structure with a plurality of light-emitting layers or a structure with a single light-emitting layer. For example, in combination with the configuration of the above tandem-type light-emitting device, a plurality of EL layers may be provided with a charge generation layer interposed therebetween in one light-emitting device, and a single or a plurality of light-emitting layers may be formed in each EL layer.

[0223] By having a microcavity structure, it becomes possible to enhance the forward emission intensity of a specific wavelength, so that power consumption can be reduced. In the case of a light-emitting device that displays an image with four sub-pixels of red, yellow, green, and blue, in addition to the luminance improvement effect by yellow light emission, a microcavity structure can be applied according to the wavelength of each color in all the sub-pixels, resulting in a light-emitting device with good characteristics.

[0224] Since the light-emitting device in this embodiment uses the light-emitting devices described in Embodiment 1 and Embodiment 2, a light-emitting device with good characteristics can be obtained. Specifically, because the light-emitting devices described in Embodiment 1 and Embodiment 2 have a low driving voltage, it is possible to make a light-emitting device with low power consumption.

[0225] As described above, the light-emitting device is suitable for use as a display device for representing images because it is possible to control each of the numerous minute light-emitting devices arranged in a matrix.

[0226] Furthermore, this embodiment can be freely combined with other embodiments.

[0227] (Embodiment 4) [Light-emitting device] The following describes an example of a light-emitting device according to one embodiment of the present invention using the above-mentioned light-emitting device.

[0228] Figure 4(A) shows a schematic top view of a light-emitting device 400 according to one embodiment of the present invention. The light-emitting device 400 has multiple red light-emitting devices 110R, multiple green light-emitting devices 110G, and multiple blue light-emitting devices 110B. In Figure 4(A), the labels R, G, and B are added within the light-emitting area of ​​each light-emitting device to simplify the distinction between them.

[0229] Light-emitting devices 110R, 110G, and 110B are each arranged in a matrix. Figure 4(A) shows a so-called stripe arrangement in which light-emitting devices of the same color are arranged in one direction. Note that the arrangement method of the light-emitting devices is not limited to this, and other arrangement methods such as delta arrangement and zigzag arrangement may be applied, or a pentile arrangement may be used.

[0230] Light-emitting devices 110R, 110G, and 110B are arranged in the X direction. In addition, light-emitting devices of the same color are arranged in the Y direction, which intersects with the X direction.

[0231] Light-emitting devices 110R, 110G, and 110B are light-emitting devices having the above configuration.

[0232] Figure 4(B) is a schematic cross-sectional view corresponding to the dashed line A1-A2 in Figure 4(A), and Figure 4(C) is a schematic cross-sectional view corresponding to the dashed line B1-B2.

[0233] Figure 4(B) shows cross-sections of light-emitting devices 110R, 110G, and 110B. Light-emitting device 110R has a first electrode 101R that functions as an anode, an EL layer 103R, an EL layer 515, and a second electrode 102 that functions as a cathode. Light-emitting device 110G has a first electrode 101G that functions as an anode, an EL layer 103G, an EL layer 515, and a second electrode 102. Light-emitting device 110B has a first electrode 101B that functions as an anode, an EL layer 103B, an EL layer 515, and a second electrode 102. The EL layer 515 and the second electrode 102 are provided in common to light-emitting devices 110R, 110G, and 110B. The EL layer 515 can also be called a common layer.

[0234] The EL layer 103R of the light-emitting device 110R has a luminescent organic compound that emits light with intensity in at least the red wavelength range. The EL layer 103G of the light-emitting device 110G has a luminescent organic compound that emits light with intensity in at least the green wavelength range. The EL layer 103B of the light-emitting device 110B has a luminescent organic compound that emits light with intensity in at least the blue wavelength range.

[0235] The adjacent first and second light-emitting devices refer to, for example, light-emitting devices 110R and 110G, and light-emitting devices 110G and 110B in Figure 4(B). Furthermore, the vertically aligned light-emitting devices of the same color in Figure 4(A) can also be considered adjacent light-emitting devices.

[0236] Each of the EL layers 103R, 103G, and 103B may have one or more of the following in addition to a layer containing a luminescent organic compound (luminescent layer): a hole injection layer, a hole transport layer, a carrier block layer, an exciton block layer, etc. The EL layer 515 has a configuration that does not have a luminescent layer. In one embodiment of the present invention, the EL layer 515 is preferably an electron transport layer and an electron injection layer.

[0237] The first electrode 101R, the first electrode 101G, and the first electrode 101B are each provided on different light-emitting devices. The second electrode 102 and the EL layer 515 are provided as a continuous layer common to each light-emitting device. A conductive film that is transparent to visible light is used on either each pixel electrode or the second electrode 102, and a conductive film that is reflective is used on the other. By making each pixel electrode transparent and the second electrode 102 reflective, a bottom-emission type display device can be made. Conversely, by making each pixel electrode reflective and the second electrode 102 transparent, a top-emission type display device can be made. Furthermore, by making both each pixel electrode and the second electrode 102 transparent, a dual-emission type display device can be made.

[0238] An insulating layer 121 is provided covering the ends of the first electrode 101R, the first electrode 101G, and the first electrode 101B. Preferably, the ends of the insulating layer 121 are tapered. The insulating layer 121 may be omitted if it is not needed.

[0239] Each of the EL layers 103R, 103G, and 103B has a region in contact with the upper surface of the pixel electrode and a region in contact with the surface of the insulating layer 121. The edges of the EL layers 103R, 103G, and 103B are located on the insulating layer 121.

[0240] As shown in FIG. 4(B), a gap is provided between two EL layers among light-emitting devices of different colors. Thus, it is preferable that the EL layer 103R, the EL layer 103G, and the EL layer 103B are provided so as not to contact each other. Thereby, it is possible to suitably prevent current from flowing through two adjacent EL layers and unintentional light emission from occurring. Therefore, the contrast can be enhanced, and a display device with high display quality can be realized.

[0241] In FIG. 4(C), an example in which the EL layer 103R is formed in a strip shape so as to be continuous in the Y direction is shown. By forming the EL layer 103R or the like in a strip shape, a space for dividing them becomes unnecessary, and the area of the non-light-emitting region between the light-emitting devices can be reduced, so that the aperture ratio can be increased. Although a cross section of the light-emitting device 110R is shown as an example in FIG. 4(C), the light-emitting device 110G and the light-emitting device 110B can have the same shape. Note that the EL layer may be separated for each light-emitting device in the Y direction.

[0242] A protective layer 131 is provided on the second electrode 102 so as 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 into each light-emitting device from above.

[0243] The protective layer 131 can have, for example, a single-layer structure or a laminated 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, a semiconductor material such as indium gallium oxide or indium gallium zinc oxide may be used as the protective layer 131.

[0244] Furthermore, a laminated film of an inorganic insulating film and an organic insulating film can also be used as the protective layer 131. For example, it is preferable to have a configuration in which an organic insulating film is sandwiched between a pair of inorganic insulating films. It is also preferable that the organic insulating film functions as a planarizing film. This makes the upper surface of the organic insulating film flat, thereby improving the coverage of the inorganic insulating film on top of it and enhancing its barrier properties. In addition, since the upper surface of the protective layer 131 is flat, it is preferable because it reduces the influence of uneven shapes caused by the structure below when a structure (e.g., a color filter, touch sensor electrodes, or lens array, etc.) is provided above the protective layer 131.

[0245] Figure 4(A) also shows a connecting electrode 101C that is electrically connected to the second electrode 102. The connecting electrode 101C is supplied with a potential (e.g., anode potential or cathode potential) to the second electrode 102. The connecting electrode 101C is located outside the display area where the light-emitting devices 110R and the like are arranged. The second electrode 102 is also shown by a dashed line in Figure 4(A).

[0246] The connecting electrode 101C can be provided along the outer perimeter of the display area. For example, it may be provided along one side of the outer perimeter of the display area, or it may be provided across two or more sides of the outer perimeter of the display area. That is, if the top surface shape of the display area is rectangular, the top surface shape of the connecting electrode 101C can be a strip, L-shape, U-shape (angle bracket shape), or square, etc.

[0247] Figure 4(D) is a schematic cross-sectional view corresponding to the dashed line C1-C2 in Figure 4(A). Figure 4(D) shows a connection portion 130 where the connecting 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 connecting electrode 101C, and a protective layer 131 is provided covering the second electrode 102. In addition, an insulating layer 121 is provided covering the end of the connecting electrode 101C.

[0248] [Example of manufacturing method 1] In the following, an example of a method for manufacturing a display device according to one aspect of the present invention will be described with reference to the drawings. Here, the light-emitting device 400 shown in the above configuration example will be used as an example. Figures 5(A) to 5(F) are schematic cross-sectional views of each step in the method for manufacturing the display device illustrated below. In addition, in Figure 5(A), etc., schematic cross-sectional views of the connection part 130 and its vicinity are also shown on the right side.

[0249] The thin films (insulating films, semiconductor films, conductive films, etc.) that make up the display device can be formed using sputtering, chemical vapor deposition (CVD), vacuum deposition, pulsed laser deposition (PLD), atomic layer deposition (ALD), and other methods. CVD methods include plasma-enhanced CVD (PECVD) and thermal CVD. One type of thermal CVD is metal-organic CVD (MOCVD).

[0250] Furthermore, thin films (insulating films, semiconductor films, conductive films, etc.) that constitute the display device can be formed by methods such as spin coating, dip coating, spray coating, inkjet printing, dispensing, screen printing, offset printing, doctor knife method, slit coating, roll coating, curtain coating, and knife coating.

[0251] Furthermore, when processing the thin films that constitute the display device, photolithography or the like can be used. In addition, the thin films may be processed by nanoimprint lithography, sandblasting, lift-off lithography, or the like. Alternatively, island-shaped thin films may be directly formed by a film deposition method using a shielding mask such as a metal mask.

[0252] There are two main methods of photolithography. One method involves forming a resist mask on the thin film to be processed, then processing the thin film by etching or other means, and removing the resist mask. The other method involves forming a photosensitive thin film, then exposing and developing it to process the thin film into the desired shape.

[0253] In photolithography, the light used for exposure can be, for example, i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), or a mixture thereof. Other light sources such as ultraviolet light, KrF laser light, or ArF laser light can also be used. Exposure may also be performed using immersion lithography. Furthermore, extreme ultraviolet (EUV) light, X-rays, etc., may be used as the light source for exposure. An electron beam can also be used instead of the light source for exposure. Using extreme ultraviolet light, X-rays, or an electron beam is preferable because it enables extremely fine processing. Note that a photomask is not required when exposure is performed by scanning a beam such as an electron beam.

[0254] For etching thin films, methods such as dry etching, wet etching, and sandblasting can be used.

[0255] [Preparation of circuit board 100] As the substrate 100, a substrate having at least sufficient heat resistance to withstand subsequent heat treatment can be used. When an insulating substrate is used as the substrate 100, glass substrates, quartz substrates, sapphire substrates, ceramic substrates, organic resin substrates, etc., can be used. In addition, semiconductor substrates such as single-crystal semiconductor substrates made of silicon, silicon carbide, etc., polycrystalline semiconductor substrates, compound semiconductor substrates such as silicon germanium, and SOI substrates can be used.

[0256] In particular, it is preferable to use a substrate 100 on which a semiconductor circuit including semiconductor elements such as transistors is formed on the semiconductor substrate or insulating substrate. It is preferable that the semiconductor circuit 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 configured.

[0257] [Formation of the first electrodes 101R, 101G, 101B and the connecting electrode 101C] Next, the first electrode 101R, the first electrode 101G, the first electrode 101B, and the connecting electrode 101C are formed on the substrate 100. First, a conductive film to be the anode (pixel electrode) is deposited, a resist mask is formed by photolithography, and unnecessary parts of the conductive film are removed by etching. After that, the resist mask is removed to form the first electrode 101R, the first electrode 101G, and the first electrode 101B.

[0258] When using a conductive film that is reflective to visible light as each pixel electrode, it is preferable to use a material (for example, silver or aluminum) that has the highest possible reflectivity across the entire wavelength range of visible light. This not only improves the light extraction efficiency of the light-emitting device but also enhances color reproduction. When a conductive film that is reflective to visible light is used as each pixel electrode, it is possible to create a so-called top-emission light-emitting device that extracts light in the direction opposite to the substrate. When a transparent conductive film is used as each pixel electrode, it is possible to create a so-called bottom-emission light-emitting device that extracts light in the direction of the substrate.

[0259] [Formation of insulating layer 121] Next, an insulating layer 121 is formed by covering the ends of the first electrode 101R, the first electrode 101G, and the first electrode 101B (Figure 5(A)). An organic insulating film or an inorganic insulating film can be used as the insulating layer 121. It is preferable that the ends of the insulating layer 121 be tapered in order to improve the step coverage of the subsequent EL film. In particular, when using an organic insulating film, it is preferable to use a photosensitive material because it is easier to control the shape of the ends depending on the exposure and development conditions. If the insulating layer 121 is not provided, it becomes possible to bring the distance between the light-emitting devices even closer, making it possible to obtain a higher-resolution light-emitting device.

[0260] [Formation of EL film 103Rb] Next, an EL film 103Rb, which will later become the EL layer 103R, is formed on the first electrode 101R, the first electrode 101G, the first electrode 101B, and the insulating layer 121.

[0261] The EL film 103Rb has a film containing at least a luminescent compound. In addition, it may have a structure in which one or more films functioning as hole transport layers, hole injection layers, electron blocking layers, electron transport layers, and electron injection layers are laminated. The EL film 103Rb can be formed by, for example, vapor deposition, sputtering, or inkjet. However, it is not limited to these, and the above-mentioned film formation methods can be used as appropriate.

[0262] As an example, it is preferable that the EL film 103Rb be a laminated film in which a hole injection layer, a hole transport layer, an emissive layer, and an electron transport layer are stacked in this order. In this case, the EL layer to be formed later may be a film having an electron injection layer 115.

[0263] It is preferable to form the EL film 103Rb so as not to be present on the connecting electrode 101C. For example, when forming the EL film 103Rb by vapor deposition (or sputtering), it is preferable to form it using a shielding mask or remove it in a later etching step so that the EL film 103Rb is not deposited on the connecting electrode 101C.

[0264] [Formation of sacrificial film 144a] Next, a sacrificial film 144a is formed by covering the EL film 103Rb. The sacrificial film 144a is also provided in contact with the upper surface of the connecting electrode 101C.

[0265] The sacrificial film 144a can be a film with high resistance to etching of each EL film, such as the EL film 103Rb, i.e., a film with a high etching selectivity ratio. Alternatively, the sacrificial film 144a can be a film with a high etching selectivity ratio with protective films, such as the protective film 146a described later. Furthermore, the sacrificial film 144a can be a film that can be removed by a wet etching method that causes minimal damage to each EL film.

[0266] As the sacrificial film 144a, for example, a metal film, alloy film, metal oxide film, semiconductor film, or inorganic film such as an inorganic insulating film can be used. The sacrificial film 144a can be formed by various film deposition methods such as sputtering, vapor deposition, CVD, and ALD.

[0267] As the sacrificial film 144a, for example, metallic materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, and tantalum, or alloy materials containing such metallic materials, can be used. In particular, it is preferable to use low-melting-point materials such as aluminum or silver.

[0268] Furthermore, metal oxides such as indium gallium zinc oxide (In-Ga-Zn oxide, also written as IGZO) can be used as the sacrificial film 144a. In addition, 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), indium gallium tin zinc oxide (In-Ga-Sn-Zn oxide), etc. can be used. Alternatively, indium tin oxide containing silicon can also be used.

[0269] Furthermore, the above-mentioned method can also be applied when element M (where M is one or more selected from aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, or magnesium) is used instead of gallium. In particular, it is preferable that M be one or more selected from gallium, aluminum, or yttrium.

[0270] Furthermore, inorganic insulating materials such as aluminum oxide, hafnium oxide, and silicon oxide can be used as the sacrificial film 144a.

[0271] Furthermore, it is preferable to use a material that is soluble in a chemically stable solvent as the sacrificial film 144a, at least for the film located on top of the EL film 103Rb. In particular, a material soluble in water or alcohol can be suitably used for the sacrificial film 144a. When forming the sacrificial film 144a, it is preferable to apply it using a wet deposition method while dissolved in a solvent such as water or alcohol, and then perform a heat treatment to evaporate the solvent. At this time, 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 103Rb.

[0272] Wet film deposition methods that can be used to form the sacrificial film 144a include spin coating, dip coating, spray coating, inkjet printing, dispensing, screen printing, offset printing, doctor knife method, slit coating, roll coating, curtain coating, and knife coating.

[0273] As the sacrificial film 144a, organic materials such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or alcohol-soluble polyamide resin can be used.

[0274] [Formation of protective film 146a] Next, a protective film 146a is formed on the sacrificial film 144a (Figure 5(B)).

[0275] The protective film 146a is used as a hard mask when etching the sacrificial film 144a later. Furthermore, the sacrificial film 144a is exposed during the subsequent processing of the protective film 146a. Therefore, a combination of films with a high etching selectivity ratio for each other is selected for the sacrificial film 144a and the protective film 146a. Thus, the film that can be used for the protective film 146a can be selected according to the etching conditions for both the sacrificial film 144a and the protective film 146a.

[0276] For example, when dry etching using a fluorine-containing gas (also called 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, or an alloy containing molybdenum and tungsten can be used for the protective film 146a. Here, metal oxide films such as IGZO and ITO can be used as sacrificial films 144a, as they allow for a higher selectivity ratio for etching (i.e., a slower etching rate) compared to the dry etching using the above-mentioned fluorine-based gas.

[0277] However, the protective film 146a can be selected from a variety of materials depending on the etching conditions of the sacrificial film 144a and the protective film 146a. For example, it can be selected from films that can be used for the sacrificial film 144a.

[0278] Furthermore, a nitride film can be used as the protective film 146a, for example. Specifically, nitrides such as silicon nitride, aluminum nitride, hafnium nitride, titanium nitride, tantalum nitride, tungsten nitride, gallium nitride, and germanium nitride can be used.

[0279] Alternatively, an oxide film can be used as the protective film 146a. Typically, oxide films or oxynitride films such as silicon oxide, silicon oxynitride, aluminum oxide, aluminum oxynitride, hafnium oxide, and hafnium oxynitride can be used.

[0280] Furthermore, an organic film that can be used for EL film 103Rb, etc., may be used as the protective film 146a. For example, the same organic film used for EL film 103Rb, EL film 103Gb, or EL film 103Bb can be used for protective film 146a. Using such an organic film is preferable because it allows the same film deposition equipment to be used for both EL film 103Rb and the other films.

[0281] [Formation of resist mask 143a] Next, a resist mask 143a is formed on the protective film 146a at a position overlapping with the first electrode 101R and at a position overlapping with the connecting electrode 101C, respectively (Figure 5(C)).

[0282] The resist mask 143a can use a resist material containing a photosensitive resin, such as a positive-type resist material or a negative-type resist material.

[0283] In this case, if a resist mask 143a is formed on the sacrificial film 144a without a protective film 146a, there is a risk that the EL film 103Rb may dissolve due to the solvent of the resist material if there are defects such as pinholes in the sacrificial film 144a. Using a protective film 146a can prevent such problems from occurring.

[0284] Furthermore, if a sacrificial film 144a is used that is less prone to defects such as pinholes, the resist mask 143a may be formed directly on the sacrificial film 144a without using the protective film 146a.

[0285] [Etching of protective film 146a] Next, the portion of the protective film 146a not covered by the resist mask 143a is removed by etching to form a strip-shaped protective layer 147a. At the same time, a protective layer 147a is also formed on the connecting electrode 101C.

[0286] When etching the protective film 146a, it is preferable to use etching conditions with a high selectivity ratio so that the sacrificial 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 suppress the reduction of the pattern of the protective film 146a.

[0287] [Removal of resist mask 143a] Next, remove the resist mask 143a (Figure 5(D)).

[0288] The resist mask 143a can be removed by wet etching or dry etching. In particular, it is preferable to remove the resist mask 143a by dry etching (also called plasma ashing) using oxygen gas as the etching gas.

[0289] In this case, the removal of the resist mask 143a is performed while the EL film 103Rb is covered by the sacrificial film 144a, thus suppressing the impact on the EL film 103Rb. In particular, since contact with oxygen can adversely affect the electrical properties of the EL film 103Rb, this method is suitable when etching is performed using oxygen gas, such as plasma ashing.

[0290] [Etching of sacrificial film 144a] Next, using the protective layer 147a as a mask, the portion of the sacrificial film 144a not covered by the protective layer 147a is removed by etching to form a strip-shaped sacrificial layer 145a (Figure 5(E)). At the same time, a sacrificial layer 145a is also formed on the connecting electrode 101C.

[0291] The sacrificial film 144a can be etched by wet etching or dry etching, but dry etching is preferred because it can suppress pattern reduction.

[0292] [Etching of EL film 103Rb and protective layer 147a] Next, the protective layer 147a is etched, and at the same time, a portion of the EL film 103Rb not covered by the sacrificial layer 145a is removed by etching, forming a strip-shaped EL layer 103R (Figure 5(F)). At the same time, the protective layer 147a on the connecting electrode 101C is also removed.

[0293] Etching the EL film 103Rb and the protective layer 147a using the same process simplifies the process and reduces the manufacturing cost of the display device, which is preferable.

[0294] In particular, for etching the EL film 103Rb, it is preferable to use dry etching with an etching gas that does not contain oxygen as its main component. This suppresses the deterioration of the EL film 103Rb and enables the realization of a highly reliable display device. Examples of etching gases that do not contain oxygen as their main component include noble gases such as CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, H2, or He. Alternatively, a mixed gas of the above gases and an oxygen-free diluent gas can be used as the etching gas.

[0295] The etching of the EL film 103Rb and the protective layer 147a may be performed separately. In this case, the EL film 103Rb may be etched first, or the protective layer 147a may be etched first.

[0296] At this point, the EL layer 103R and the connecting electrode 101C are covered by the sacrificial layer 145a.

[0297] [Formation of EL film 103Gb] Next, an EL film 103Gb, which will later become the EL layer 103G, is formed on the sacrificial layer 145a, the insulating layer 121, the first electrode 101G, and the first electrode 101B. At this time, it is preferable not to provide the EL film 103Gb on the connecting electrode 101C, similar to the EL film 103Rb described above.

[0298] The method for forming the EL film 103Gb can be described by referring to the description of the EL film 103Rb above.

[0299] [Formation of sacrificial film 144b] Next, a sacrificial film 144b is formed on the EL film 103Gb. The sacrificial film 144b can be formed in the same manner as the sacrificial film 144a. In particular, it is preferable to use the same material for the sacrificial film 144b as for the sacrificial film 144a.

[0300] At the same time, a sacrificial film 144a is formed on the connecting electrode 101C, covering the sacrificial layer 145a.

[0301] [Formation of protective film 146b] Next, a protective film 146b is formed on the sacrificial film 144b. The protective film 146b can be formed in the same manner as the protective film 146a. In particular, it is preferable to use the same material for the protective film 146b as for the protective film 146a.

[0302] [Formation of resist mask 143b] Next, a resist mask 143b is formed on the protective film 146b in the region overlapping with the first electrode 101G and the region overlapping with the connecting electrode 101C (Figure 6(A)).

[0303] The resist mask 143b can be formed in the same manner as the resist mask 143a.

[0304] [Etching of protective film 146b] Next, the portion of the protective film 146b not covered by the resist mask 143b is removed by etching to form a strip-shaped protective layer 147b (Figure 6(B)). At the same time, a protective layer 147b is also formed on the connecting electrode 101C.

[0305] For etching of protective film 146b, the description of protective film 146a above can be applied.

[0306] [Removal of resist mask 143b] Next, remove the resist mask 143b. The removal of resist mask 143b can be done by referring to the description of resist mask 143a above.

[0307] [Etching of sacrificial film 144b] Next, using the protective layer 147b as a mask, the portion of the sacrificial film 144b not covered by the protective layer 147b is removed by etching to form a strip-shaped sacrificial layer 145b. At the same time, a sacrificial layer 145b is also formed on the connecting electrode 101C. Sacrificial layers 145a and 145b are stacked on the connecting electrode 101C.

[0308] The etching of the sacrificial film 144b can be performed by referring to the description of the sacrificial film 144a above.

[0309] [Etching of EL film 103Gb and protective layer 147b] Next, the protective layer 147b is etched, and at the same time, a portion of the EL film 103Gb that is not covered by the sacrificial layer 145b is removed by etching, forming a strip-shaped EL layer 103G (Figure 6(C)). At the same time, the protective layer 147b on the connecting electrode 101C is also removed.

[0310] Etching of the EL film 103Gb and protective layer 147b can be performed by referring to the description of the EL film 103Rb and protective layer 147a above.

[0311] In this case, the EL layer 103R is protected by the sacrificial layer 145a, thus preventing it from being damaged during the etching process of the EL film 103Gb.

[0312] In this way, the strip-shaped EL layer 103R and the strip-shaped EL layer 103G can be manufactured with high positional accuracy.

[0313] [Formation of EL layer 103B] By performing the above steps on the EL film 103Bb (not shown), island-shaped EL layers 103B and island-shaped sacrificial layers 145c can be formed (Figure 6(D)).

[0314] Specifically, after the formation of the EL layer 103G, the EL film 103Bb, sacrificial film 144c, protective film 146c, and resist mask 143c (none of which are shown) are formed in order. Next, the protective film 146c is etched to form a protective layer 147c (not shown), and then the resist mask 143c is removed. Subsequently, the sacrificial film 144c is etched to form a sacrificial layer 145c. After that, the protective layer 147c and the EL film 103Bb are etched to form a strip-shaped EL layer 103B.

[0315] Furthermore, after the formation of the EL layer 103B, a sacrificial layer 145c is simultaneously formed on the connecting electrode 101C. Sacrificial layers 145a, 145b, and 145c are stacked on the connecting electrode 101C.

[0316] [Removal of the sacrificial layer] Next, sacrificial layers 145a, 145b, and 145c are removed, exposing the upper surfaces of EL layers 103R, 103G, and 103B (Figure 6(E)). At the same time, the upper surface of the connecting electrode 101C is also exposed.

[0317] In this process, the surface of the EL layer may be damaged to some extent by exposure to etching gas or etching solution. For example, if patterning is performed after forming the electron transport layer, the surface of the electron transport layer may be damaged, reducing the electron injection capacity. In such cases, the electron injection capacity can be improved by using a material with a GSP_slope of 20 or more for the electron transport layer, the hole blocking layer, or both. Thus, a light-emitting device according to one aspect of the present invention can be suitably used in light-emitting devices and display devices manufactured using a photoetching method.

[0318] Sacrificial layers 145a, 145b, and 145c can be removed by wet etching or dry etching. In this case, it is preferable to use a method that minimizes damage to EL layers 103R, 103G, and 103B. In particular, wet etching is preferred. For example, wet etching using an aqueous solution of tetramethylammonium hydroxide (TMAH), dilute hydrofluoric acid, oxalic acid, phosphoric acid, acetic acid, nitric acid, or a mixture thereof is preferred.

[0319] Alternatively, it is preferable to remove the sacrificial layers 145a, 145b, and 145c by dissolving them in a solvent such as water or alcohol. Here, various alcohols can be used as the alcohol that can dissolve the sacrificial layers 145a, 145b, and 145c, such as ethyl alcohol, methyl alcohol, isopropyl alcohol (IPA), or glycerin.

[0320] After removing sacrificial layers 145a, 145b, and 145c, it is preferable to perform a drying treatment to remove water contained inside EL layers 103R, 103G, and 103B, as well as water adsorbed on the surface. For example, it is preferable to perform a heat treatment under an inert gas atmosphere or a reduced pressure atmosphere. The heat treatment can be performed at a substrate temperature of 50°C to 200°C, preferably 60°C to 150°C, and more preferably 70°C to 120°C. A reduced pressure atmosphere is preferable because it allows drying at a lower temperature.

[0321] In this way, EL layer 103R, EL layer 103G, and EL layer 103B can be manufactured separately.

[0322] [Formation of EL layer 515] Next, an EL layer 515 is formed over the EL layers 103R, 103G, and 103B. The EL layer 515 includes layers that have the function of injecting and transporting electrons, such as an electron injection layer.

[0323] The EL layer 515 can be deposited using the same method as the EL film 103Rb. When depositing the EL layer 515 by vapor deposition, it is preferable to use a shielding mask to prevent the EL layer 515 from being deposited on the connecting electrode 101C.

[0324] [Formation of the second electrode 102] Next, the electron injection layer 115 and the connecting electrode 101C are covered to form the second electrode 102 (Figure 6(F)).

[0325] The second electrode 102 can be formed by a film deposition method such as vapor deposition or sputtering. Alternatively, a film formed by vapor deposition and a film formed by sputtering may be laminated together. In this case, it is preferable to form the second electrode 102 so as to encompass the region in which the electron injection layer 115 is formed. That is, the edge of the electron injection layer 115 can overlap with the second electrode 102. It is preferable to form the second electrode 102 using a shielding mask.

[0326] The second electrode 102 is electrically connected to the connecting electrode 101C outside the display area.

[0327] [Formation of a protective layer] Next, a protective layer is formed on the second electrode 102. For the formation of the inorganic insulating film used in the protective layer, sputtering, PECVD, or ALD methods are preferred. The ALD method is particularly preferred because it offers excellent step coverage and is less prone to defects such as pinholes. Furthermore, for the formation of the organic insulating film, the inkjet method is preferred because it allows for the formation of a uniform film in the desired area.

[0328] Based on the above, a light-emitting device according to one aspect of the present invention can be manufactured.

[0329] In the above example, the case where the second electrode 102 and the electron injection layer 115 are formed with different upper surface shapes is shown, but they may also be formed in the same region.

[0330] (Embodiment 5) This embodiment describes an example of the configuration of a display device according to one aspect of the present invention.

[0331] The display device of this embodiment can be a high-resolution display device or a large-screen display device. Therefore, the display device of this embodiment can be used in electronic devices with relatively large screens, such as television sets, desktop or notebook personal computers, computer monitors, digital signage, and large game machines such as pachinko machines, as well as in the display units of digital cameras, digital video cameras, digital photo frames, mobile phones, portable game consoles, smartphones, smartwatches, tablet devices, personal digital assistants, and audio playback devices.

[0332] [Light-emitting device 400A] Figure 7 shows a perspective view of the light-emitting device 400A, and Figure 8(A) shows a cross-sectional view of the light-emitting device 400A.

[0333] The light-emitting device 400A has a configuration in which substrate 452 and substrate 451 are bonded together. In Figure 8, substrate 452 is indicated by a dashed line.

[0334] The light-emitting device 400A includes a display unit 462, a circuit 464, wiring 465, etc. Figure 8 shows an example in which IC 473 and FPC 472 are mounted on the light-emitting device 400A. Therefore, the configuration shown in Figure 8 can also be described as a display module having a light-emitting device 400A, an IC (integrated circuit), and an FPC.

[0335] For example, a scan line drive circuit can be used as circuit 464.

[0336] Wiring 465 has the function of supplying signals and power to the display unit 462 and the circuit 464. These signals and power are input to wiring 465 from an external source via FPC 472 or from IC 473.

[0337] Figure 8 shows an example in which IC 473 is provided on the substrate 451 using the COG (Chip On Glass) method or COF (Chip On Film) method, etc. IC 473 can be an IC having, for example, a scan line drive circuit or a signal line drive circuit. Note that the light-emitting device 400A and the display module may be configured without an IC. Alternatively, the IC may be mounted on the FPC using the COF method, etc.

[0338] Figure 8(A) shows an example of a cross-section obtained by cutting a portion of the area including the FPC 472, a portion of the circuit 464, a portion of the display unit 462, and a portion of the area including the end portion of the light-emitting device 400A.

[0339] The light-emitting device 400A shown in Figure 8(A) has a transistor 201, a transistor 205, a light-emitting device 430a that emits red light, a light-emitting device 430b that emits green light, and a light-emitting device 430c that emits blue light, etc., between substrates 451 and 452.

[0340] The light-emitting devices 430a, 430b, and 430c can be the light-emitting devices exemplified in Embodiment 1.

[0341] Here, if the pixels of the display device have three types of subpixels, each having a light-emitting device that emits a different color from the others, examples of these three subpixels include subpixels of three colors: R, G, and B; and subpixels of three colors: yellow (Y), cyan (C), and magenta (M). If there are four such subpixels, examples of these four subpixels include subpixels of four colors: R, G, B, and white (W); and subpixels of four colors: R, G, B, and Y.

[0342] The protective layer 416 and the substrate 452 are bonded together via an adhesive layer 442. For sealing the light-emitting device, a solid sealing structure or a hollow sealing structure can be applied. In Figure 8(A), the space 443 surrounded by the substrate 452, the adhesive layer 442, and the substrate 451 is filled with an inert gas (such as nitrogen or argon), demonstrating the application of a hollow sealing structure. The adhesive layer 442 may be provided overlapping the light-emitting device. Alternatively, the space 443 surrounded by the substrate 452, the adhesive layer 442, and the substrate 451 may be filled with a resin different from that of the adhesive layer 442.

[0343] The light-emitting devices 430a, 430b, and 430c have an optical adjustment layer between the pixel electrode and the EL layer. Light-emitting device 430a has an optical adjustment layer 426a, light-emitting device 430b has an optical adjustment layer 426b, and light-emitting device 430c has an optical adjustment layer 426c. Details of the light-emitting devices can be found in Embodiment 1.

[0344] The pixel electrodes 411a, 411b, and 411c are each connected to the conductive layer 222b of the transistor 205 through an opening provided in the insulating layer 214.

[0345] The edges of the pixel electrodes and the optical adjustment layer are covered by an insulating layer 421. The pixel electrodes contain a material that reflects visible light, and the counter electrodes contain a material that transmits visible light.

[0346] The light emitted by the light-emitting device is projected onto the substrate 452. It is preferable to use a material with high transparency to visible light for the substrate 452.

[0347] Both transistors 201 and 205 are formed on the substrate 451. These transistors can be manufactured using the same materials and the same process.

[0348] On the substrate 451, insulating layers 211, 213, 215, and 214 are provided in this order. A portion of insulating layer 211 functions as a gate insulating layer for each transistor. A portion of insulating layer 213 functions as a gate insulating layer for each transistor. Insulating layer 215 is provided covering the transistors. Insulating layer 214 is provided covering the transistors and functions as a planarization layer. The number of gate insulating layers and insulating layers covering the transistors are not limited and may be a single layer or two or more layers, respectively.

[0349] It is preferable to use a material that does not easily allow impurities such as water and hydrogen to diffuse into at least one layer of the insulating layer covering the transistor. This allows the insulating layer to function as a barrier layer. With such a configuration, the diffusion of impurities from the outside into the transistor can be effectively suppressed, thereby improving the reliability of the display device.

[0350] It is preferable to use inorganic insulating films for insulating layer 211, insulating layer 213, and insulating layer 215. Examples of inorganic insulating films that can be used include silicon nitride film, silicon oxide nitride film, silicon oxide film, silicon nitride oxide film, aluminum oxide film, and aluminum nitride film. Alternatively, hafnium oxide film, yttrium oxide film, zirconium oxide film, gallium oxide film, tantalum oxide film, magnesium oxide film, lanthanum oxide film, cerium oxide film, and neodymium oxide film may also be used. Furthermore, two or more of the above insulating films may be laminated together.

[0351] Here, organic insulating films often have lower barrier properties than inorganic insulating films. Therefore, it is preferable that the organic insulating film has an opening near the end of the light-emitting device 400A. This prevents impurities from entering through the organic insulating film from the end of the light-emitting device 400A. Alternatively, the organic insulating film may be formed so that its end is inward from the end of the light-emitting device 400A, so that the organic insulating film is not exposed at the end of the light-emitting device 400A.

[0352] An organic insulating film is preferred for the insulating layer 214, which functions as a planarizing layer. Examples of materials that can be used as the organic insulating film include acrylic resins, polyimide resins, epoxy resins, polyamide resins, polyimidoamide resins, siloxane resins, benzocyclobutene resins, phenolic resins, and precursors of these resins.

[0353] In the region 228 shown in Figure 8(A), an opening is formed in the insulating layer 214. This prevents impurities from entering the display unit 462 from the outside through the insulating layer 214, even when an organic insulating film is used for the insulating layer 214. Therefore, the reliability of the light-emitting device 400A can be improved.

[0354] Transistors 201 and 205 have a conductive layer 221 that functions as a gate, an insulating layer 211 that functions as a gate insulating layer, conductive layers 222a and 222b that function as source and drain, a semiconductor layer 231, an insulating layer 213 that functions as a gate insulating layer, and a conductive layer 223 that functions as a gate. Here, the same hatching pattern is applied to multiple layers obtained by processing the same conductive film. The insulating layer 211 is located between the conductive layer 221 and the semiconductor layer 231. The insulating layer 213 is located between the conductive layer 223 and the semiconductor layer 231.

[0355] The transistor structure of the display device of this embodiment is not particularly limited. For example, planar transistors, staggered transistors, inverse staggered transistors, etc., can be used. Furthermore, either a top-gate or bottom-gate transistor structure may be used. Alternatively, gates may be provided above and below the semiconductor layer in which the channel is formed.

[0356] Transistors 201 and 205 are configured in which a semiconductor layer on which a channel is formed is sandwiched between two gates. The transistors may be driven by connecting the two gates and supplying them with the same signal. Alternatively, the threshold voltage of the transistors may be controlled by applying a potential to control the threshold voltage to one of the two gates and a potential to drive the other gate.

[0357] The crystallinity of the semiconductor material used in the transistor is not particularly limited; amorphous semiconductors, single-crystal semiconductors, or semiconductors with crystalline properties other than single crystals (microcrystalline semiconductors, polycrystalline semiconductors, or semiconductors with crystalline regions in part) may be used. Using a single-crystal semiconductor or a semiconductor with crystalline properties is preferable because it can suppress the degradation of transistor characteristics.

[0358] The semiconductor layer of the transistor preferably has a metal oxide (also called an oxide semiconductor). In other words, the display device of this embodiment preferably uses a transistor (hereinafter referred to as an OS transistor) that uses a metal oxide in the channel formation region. Alternatively, the semiconductor layer of the transistor may have silicon. Examples of silicon include amorphous silicon and crystalline silicon (low-temperature polysilicon, single-crystal silicon, etc.).

[0359] The semiconductor layer preferably comprises, for example, indium, M (where M is one or more selected from gallium, aluminum, silicon, boron, yttrium, tin, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium), and zinc. In particular, M is preferably one or more selected from aluminum, gallium, yttrium, and tin.

[0360] In particular, it is preferable to use an oxide (also written as IGZO) containing indium (In), gallium (Ga), and zinc (Zn) as the semiconductor layer.

[0361] When the semiconductor layer is an In-M-Zn oxide, it is preferable that the atomic ratio of In in the In-M-Zn oxide is equal to or greater than the atomic ratio of M. Examples of such In-M-Zn oxide atomic ratios of metal elements include compositions where In:M:Zn=1:1:1 or close to it, In:M:Zn=1:1:1.2 or close to it, In:M:Zn=2:1:3 or close to it, In:M:Zn=3:1:2 or close to it, In:M:Zn=4:2:3 or close to it, In:M:Zn=4:2:4.1 or close to it, In:M:Zn=5:1:3 or close to it, In:M:Zn=5:1:6 or close to it, In:M:Zn=5:1:7 or close to it, In:M:Zn=5:1:8 or close to it, In:M:Zn=6:1:6 or close to it, In:M:Zn=5:2:5 or close to it, and so on. Note that "close to it" compositions include a range of ±30% of the desired atomic ratio.

[0362] For example, when describing a composition with an atomic ratio of In:Ga:Zn = 4:2:3 or a similar ratio, it includes cases where, when the atomic ratio of In is 4, the atomic ratio of Ga is between 1 and 3, and the atomic ratio of Zn is between 2 and 4. Also, when describing a composition with an atomic ratio of In:Ga:Zn = 5:1:6 or a similar ratio, it includes cases where, when the atomic ratio of In is 5, the atomic ratio of Ga is greater than 0.1 and 2 or less, and the atomic ratio of Zn is between 5 and 7. Furthermore, when describing a composition with an atomic ratio of In:Ga:Zn = 1:1:1 or a similar ratio, it includes cases where, when the atomic ratio of In is 1, the atomic ratio of Ga is greater than 0.1 and 2 or less, and the atomic ratio of Zn is greater than 0.1 and 2 or less.

[0363] The transistors in circuit 464 and the transistors in display unit 462 may have the same structure or different structures. The structures of the multiple transistors in circuit 464 may all be the same or there may be two or more different structures. Similarly, the structures of the multiple transistors in display unit 462 may all be the same or there may be two or more different structures.

[0364] A connection portion 204 is provided in the region of substrate 451 where substrate 452 does not overlap. At the connection portion 204, wiring 465 is electrically connected to FPC 472 via conductive layer 466 and connection layer 242. The conductive layer 466 is shown as an example of a laminated structure consisting of a conductive film obtained by processing the same conductive film as the pixel electrode and a conductive film obtained by processing the same conductive film as the optical adjustment layer. The conductive layer 466 is exposed on the upper surface of the connection portion 204. This allows the connection portion 204 and FPC 472 to be electrically connected via the connection layer 242.

[0365] It is preferable to provide a light-shielding layer 417 on the surface of the substrate 452 that faces the substrate 451. Various optical components can also be arranged on the outside of the substrate 452. Examples of optical components include polarizing plates, phase difference plates, light diffusion layers (such as diffusion films), anti-reflective layers, and light-collecting films. Furthermore, an antistatic film to suppress the adhesion of dust, a water-repellent film to make it difficult for dirt to adhere, a hard coat film to suppress the occurrence of scratches during use, and an impact-absorbing layer may also be arranged on the outside of the substrate 452.

[0366] By providing a protective layer 416 that covers the light-emitting device, it is possible to suppress the ingress of impurities such as water into the light-emitting device and improve the reliability of the light-emitting device.

[0367] In the region 228 near the end of the light-emitting device 400A, it is preferable that the insulating layer 215 and the protective layer 416 are in contact with each other through an opening in the insulating layer 214. In particular, it is preferable that the inorganic insulating film of the insulating layer 215 and the inorganic insulating film of the protective layer 416 are in contact with each other. This makes it possible to suppress the entry of impurities into the display unit 462 from the outside through the organic insulating film. Therefore, the reliability of the light-emitting device 400A can be improved.

[0368] Figure 8(B) shows an example in which the protective layer 416 has a three-layer structure. In Figure 8(B), the protective layer 416 has an inorganic insulating layer 416a on the light-emitting device 430c, an organic insulating layer 416b on the inorganic insulating layer 416a, and an inorganic insulating layer 416c on the organic insulating layer 416b.

[0369] The edges of the inorganic insulating layer 416a and the inorganic insulating layer 416c extend outward beyond the edge of the organic insulating layer 416b and are in contact with each other. Furthermore, the inorganic insulating layer 416a is in contact with the insulating layer 215 (inorganic insulating layer) through an opening in the insulating layer 214 (organic insulating layer). As a result, the light-emitting device can be surrounded by the insulating layer 215 and the protective layer 416, thereby improving the reliability of the light-emitting device.

[0370] Thus, the protective layer 416 may have a laminated structure of an organic insulating film and an inorganic insulating film. In this case, it is preferable that the edges of the inorganic insulating film extend outward more than the edges of the organic insulating film.

[0371] Substrates 451 and 452 can be made of glass, quartz, ceramic, sapphire, resin, metal, alloy, semiconductor, etc., respectively. The substrate on the side that extracts light from the light-emitting device should be made of a material that transmits the light. Using flexible materials for substrates 451 and 452 can increase the flexibility of the display device. Alternatively, a polarizing plate may be used as substrate 451 or substrate 452.

[0372] Substrates 451 and 452 can be made from polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyacrylonitrile resin, acrylic resin, polyimide resin, polymethyl methacrylate resin, polycarbonate (PC) resin, polyethersulfone (PES) resin, polyamide resin (nylon, aramid, etc.), polysiloxane resin, cycloolefin resin, polystyrene resin, polyamide-imide resin, polyurethane resin, polyvinyl chloride resin, polyvinylidene chloride resin, polypropylene resin, polytetrafluoroethylene (PTFE) resin, ABS resin, cellulose nanofiber, etc. One or both of substrates 451 and 452 may be made of glass of a thickness sufficient to provide flexibility.

[0373] Furthermore, when a circular polarizing plate is superimposed on a display device, it is preferable to use a substrate with high optical isotropy for the substrate of the display device. A substrate with high optical isotropy has low birefringence (or a small amount of birefringence).

[0374] For substrates with high optical isotropy, the absolute value of the retardation (phase difference) is preferably 30 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less.

[0375] Examples of films with high optical isotropy include triacetylcellulose (TAC, also known as cellulose triacetate) film, cycloolefin polymer (COP) film, cycloolefin copolymer (COC) film, and acrylic film.

[0376] Furthermore, when using a film as the substrate, the film may absorb water, potentially causing wrinkles or other shape changes in the display panel. Therefore, it is preferable to use a film with low water absorption for the substrate. For example, it is preferable to use a film with a water absorption rate of 1% or less, more preferable to use a film with a water absorption rate of 0.1% or less, and even more preferable to use a film with a water absorption rate of 0.01% or less.

[0377] Various types of curing adhesives can be used as the adhesive layer, including UV-curing adhesives, reaction-curing adhesives, thermosetting adhesives, and anaerobic adhesives. Examples of these adhesives include epoxy resins, acrylic resins, silicone resins, phenolic resins, polyimide resins, imide resins, PVC (polyvinyl chloride) resins, PVB (polyvinyl butyral) resins, and EVA (ethylene vinyl acetate) resins. Materials with low moisture permeability, such as epoxy resins, are particularly preferred. Two-component mixed resins may also be used. Adhesive sheets may also be used.

[0378] As the connecting layer 242, an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), etc., can be used.

[0379] Materials that can be used for conductive layers such as the gate, source, and drain of transistors, as well as various wirings and electrodes that constitute display devices, include metals such as aluminum, titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum, silver, tantalum, and tungsten, as well as alloys mainly composed of these metals. Films containing these materials can be used as single layers or in a multilayer structure.

[0380] Furthermore, conductive oxides such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, and zinc oxide containing gallium, or graphene can be used as the light-transmitting conductive material. Alternatively, metallic materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, and titanium, or alloy materials containing such metallic materials, can be used. Alternatively, nitrides of such metallic materials (e.g., titanium nitride) may be used. When using metallic materials or alloy materials (or their nitrides), it is preferable to make them thin enough to be light-transmitting. In addition, a laminated film of the above materials can be used as a conductive layer. For example, using a laminated film of a silver-magnesium alloy and indium tin oxide is preferable because it can enhance conductivity. These can also be used as conductive layers for various wirings and electrodes that constitute a display device, and as conductive layers (conductive layers that function as pixel electrodes or common electrodes) in light-emitting devices.

[0381] Examples of insulating materials that can be used for each insulating layer include resins such as acrylic resin and epoxy resin, and inorganic insulating materials such as silicon oxide, silicon oxide nitride, silicon nitride, silicon oxide, and aluminum oxide.

[0382] [Light-emitting device 400B] Figure 9(A) shows a cross-sectional view of the light-emitting device 400B. The perspective view of the light-emitting device 400B is the same as that of the light-emitting device 400A (Figure 7). Figure 9(A) shows examples of cross-sections of the light-emitting device 400B when a portion of the area including the FPC 472, a portion of the circuit 464, and a portion of the display unit 462 are cut. In Figure 9(A), an example of a cross-section is shown when a portion of the display unit 462, in particular, including the light-emitting device 430b that emits green light and the light-emitting device 430c that emits blue light, is cut. Note that explanations of parts that are the same as those of the light-emitting device 400A may be omitted.

[0383] The light-emitting device 400B shown in Figure 9(A) has transistors 202, 210, light-emitting devices 430b and 430c, etc., between substrates 453 and 454.

[0384] The substrate 454 and the protective layer 416 are bonded together via an adhesive layer 442. The adhesive layer 442 is provided in superimposed on the light-emitting devices 430b and 430c, respectively, and a solid encapsulation structure is applied to the light-emitting device 400B.

[0385] The substrate 453 and the insulating layer 212 are bonded together by an adhesive layer 455.

[0386] The method for manufacturing the light-emitting device 400B involves first bonding a fabrication substrate, on which an insulating layer 212, transistors, light-emitting devices, etc., are provided, to a substrate 454 on which a light-shielding layer 417 is provided, using an adhesive layer 442. Then, the fabrication substrate is peeled off and a substrate 453 is attached to the exposed surface, thereby transferring the components formed on the fabrication substrate to the substrate 453. It is preferable that both the substrate 453 and the substrate 454 are flexible. This increases the flexibility of the light-emitting device 400B.

[0387] The insulating layer 212 can be made of an inorganic insulating film that can be used for insulating layer 211, insulating layer 213, and insulating layer 215, respectively.

[0388] The pixel electrodes are connected to the conductive layer 222b of the transistor 210 through an opening in the insulating layer 214. The conductive layer 222b is connected to the low-resistance region 231n through openings in the insulating layers 215 and 225. The transistor 210 has the function of controlling the driving of the light-emitting device.

[0389] The ends of the pixel electrodes are covered by an insulating layer 421.

[0390] The light emitted by the light-emitting devices 430b and 430c is emitted towards the substrate 454. It is preferable to use a material with high transmittance to visible light for the substrate 454.

[0391] A connection portion 204 is provided in the region of substrate 453 that does not overlap with substrate 454. At the connection portion 204, wiring 465 is electrically connected to FPC 472 via conductive layer 466 and connection layer 242. The conductive layer 466 can be obtained by processing the same conductive film as the pixel electrode. This allows the connection portion 204 and FPC 472 to be electrically connected via the connection layer 242.

[0392] Transistors 202 and 210 each have a conductive layer 221 that functions as a gate, an insulating layer 211 that functions as a gate insulating layer, a semiconductor layer having a channel forming region 231i and a pair of low-resistance regions 231n, a conductive layer 222a connected to one of the pair of low-resistance regions 231n, a conductive layer 222b connected to the other of the pair of low-resistance regions 231n, an insulating layer 225 that functions as a gate insulating layer, a conductive layer 223 that functions as a gate, and an insulating layer 215 covering the conductive layer 223. The insulating layer 211 is located between the conductive layer 221 and the channel forming region 231i. The insulating layer 225 is located between the conductive layer 223 and the channel forming region 231i.

[0393] The conductive layer 222a and the conductive layer 222b are each connected to the low-resistance region 231n via openings provided in the insulating layer 215. Of the conductive layer 222a and the conductive layer 222b, one functions as a source and the other functions as a drain.

[0394] Figure 9(A) shows an example in which the insulating layer 225 covers the top and sides of the semiconductor layer. The conductive layer 222a and conductive layer 222b are connected to the low-resistance region 231n through openings provided in the insulating layer 225 and insulating layer 215, respectively.

[0395] On the other hand, in the transistor 209 shown in Figure 9(B), the insulating layer 225 overlaps with the channel formation region 231i of the semiconductor layer 231, but does not overlap with the low-resistance region 231n. For example, the structure shown in Figure 9(B) can be fabricated by processing the insulating layer 225 using the conductive layer 223 as a mask. In Figure 9(B), an insulating layer 215 is provided covering the insulating layer 225 and the conductive layer 223, and the conductive layers 222a and 222b are connected to the low-resistance region 231n, respectively, through openings in the insulating layer 215. Furthermore, an insulating layer 218 covering the transistor may also be provided.

[0396] The configuration examples illustrated in this embodiment, and the corresponding drawings, etc., can be appropriately combined with other configuration examples or drawings, etc., at least in part.

[0397] This embodiment can be implemented in appropriate combination with other embodiments described herein, at least in part.

[0398] (Embodiment 6) In this embodiment, a different configuration example of a display device will be described.

[0399] The display device of this embodiment can be a high-definition display device. Therefore, the display device of this embodiment can be used in the display section of wearable devices that can be worn on the head, such as information terminals (wearable devices) such as wristwatches and bracelets, as well as VR devices such as head-mounted displays and AR devices such as glasses.

[0400] [Display Module] Figure 10(A) shows a perspective view of the display module 280. The display module 280 includes a light-emitting device 400C and an FPC 290. Note that the display device of the display module 280 is not limited to the light-emitting device 400C, but may also be the light-emitting device 400D or light-emitting device 400E, which will be described later.

[0401] The display module 280 has substrates 291 and 292. The display module 280 has a display unit 281. The display unit 281 is an area in the display module 280 that displays an image, and is an area in which light from each pixel provided in the pixel unit 284, which will be described later, can be seen.

[0402] Figure 10(B) shows a schematic perspective view illustrating the configuration of the substrate 291. On the substrate 291, a circuit section 282, a pixel circuit section 283 on the circuit section 282, and a pixel section 284 on the pixel circuit section 283 are stacked. In addition, a terminal section 285 for connecting to the FPC 290 is provided in the portion of the substrate 291 that does not overlap with the pixel section 284. The terminal section 285 and the circuit section 282 are electrically connected by a wiring section 286, which is composed of multiple wires.

[0403] The pixel section 284 has multiple pixels 284a arranged periodically. A magnified view of a single pixel 284a is shown on the right side of Figure 10(B). Each pixel 284a has light-emitting devices 430a, 430b, and 430c, each with a different emission color. The multiple light-emitting devices may be arranged in a stripe pattern as shown in Figure 10(B). A stripe pattern allows for a high-density arrangement of pixel circuits, thus providing a high-resolution display device. Furthermore, various arrangement methods such as delta and pentile patterns can be applied.

[0404] The pixel circuit section 283 has a plurality of pixel circuits 283a arranged periodically.

[0405] A single pixel circuit 283a is a circuit that controls the light emission of three light-emitting devices in a single pixel 284a. A single pixel circuit 283a may be configured to have three circuits that control the light emission of one light-emitting device. For example, a pixel circuit 283a can be configured to have at least one selection transistor, one current control transistor (drive transistor), and a capacitive element for each light-emitting device. In this case, a gate signal is input to the gate of the selection transistor, and a source signal is input to either the source or the drain. This realizes an active-matrix type display device.

[0406] The circuit section 282 has circuits for driving each pixel circuit 283a of the pixel circuit section 283. For example, it is preferable to have one or both of a gate line drive circuit and a source line drive circuit. In addition, it may have at least one of the following: an arithmetic circuit, a memory circuit, and a power supply circuit.

[0407] The FPC290 functions as wiring for supplying video signals or power potential, etc., to the circuit section 282 from an external source. An IC may also be mounted on the FPC290.

[0408] The display module 280 can be configured such that one or both of the pixel circuit section 283 and the circuit section 282 are stacked on the lower side of the pixel section 284, thereby enabling an extremely high aperture ratio (effective display area ratio) of the display section 281. For example, the aperture ratio of the display section 281 can be 40% or more and less than 100%, preferably 50% or more and 95%, and more preferably 60% or more and 95%. Furthermore, it is possible to arrange the pixels 284a at an extremely high density, enabling an extremely high resolution of the display section 281. For example, it is preferable that the pixels 284a in the display section 281 are arranged with a resolution of 20000 ppi or more, preferably 3000 ppi or more, more preferably 5000 ppi or more, and even more preferably 6000 ppi or more, and with a resolution of 20000 ppi or less, or 30000 ppi or less.

[0409] Because such a display module 280 is extremely high-resolution, it can be suitably used in VR devices such as head-mounted displays, or in glasses-type AR devices. For example, even in a configuration where the display part of the display module 280 is viewed through lenses, the display module 280 has an extremely high-resolution display part 281, so even when the display part is magnified with lenses, pixels are not visible, allowing for a highly immersive display. Furthermore, the display module 280 is not limited to this, and can be suitably used in electronic devices with relatively small display parts. For example, it can be suitably used in the display part of wearable electronic devices such as wristwatches.

[0410] [Light-emitting device 400C] The light-emitting device 400C shown in Figure 11 comprises a substrate 301, light-emitting devices 430a, 430b, and 430c, a capacitor 240, and a transistor 310.

[0411] Substrate 301 corresponds to substrate 291 in Figures 10(A) and 10(B).

[0412] The transistor 310 is a transistor having a channel-forming region in the substrate 301. The substrate 301 can be a semiconductor substrate such as a single-crystal silicon substrate. The transistor 310 comprises a portion of the substrate 301, a conductive layer 311, a low-resistance region 312, an insulating layer 313, and an insulating layer 314. The conductive layer 311 functions as a gate electrode. The insulating layer 313 is located between the substrate 301 and the conductive layer 311 and functions as a gate insulating layer. The low-resistance region 312 is a region of the substrate 301 doped with impurities and functions as either a source or a drain. The insulating layer 314 covers the side surface of the conductive layer 311 and functions as an insulating layer.

[0413] Furthermore, an element isolation layer 315 is provided between two adjacent transistors 310 so as to be embedded in the substrate 301.

[0414] Furthermore, an insulating layer 261 is provided covering the transistor 310, and a capacitance 240 is provided on the insulating layer 261.

[0415] Capacitor 240 has a conductive layer 241, a conductive layer 245, and an insulating layer 243 located between them. The conductive layer 241 functions as one electrode of the capacitor 240, the conductive layer 245 functions as the other electrode of the capacitor 240, and the insulating layer 243 functions as the dielectric of the capacitor 240.

[0416] The conductive layer 241 is provided on the insulating layer 261 and embedded in the insulating layer 254. The conductive layer 241 is electrically connected to either the source or drain of the transistor 310 by a plug 271 embedded in the insulating layer 261. The insulating layer 243 is provided covering the conductive layer 241. The conductive layer 245 is provided in the region that overlaps with the conductive layer 241 via the insulating layer 243.

[0417] An insulating layer 255 is provided covering the capacitance 240, and light-emitting devices 430a, 430b, 430c, etc. are provided on the insulating layer 255. A protective layer 416 is provided on the light-emitting devices 430a, 430b, 430c, and a substrate 420 is bonded to the upper surface of the protective layer 416 by a resin layer 419.

[0418] The pixel electrodes of the light-emitting device are electrically connected to either the source or drain of the transistor 310 by plugs 256 embedded in the insulating layer 255, a conductive layer 241 embedded in the insulating layer 254, and plugs 271 embedded in the insulating layer 261.

[0419] [Light-emitting device 400D] The light-emitting device 400D shown in Figure 12 differs from the light-emitting device 400C mainly in its transistor configuration. Note that explanations of parts similar to the light-emitting device 400C may be omitted.

[0420] Transistor 320 is a transistor in which a metal oxide (also called an oxide semiconductor) is applied to the semiconductor layer where the channel is formed.

[0421] The transistor 320 has a semiconductor layer 321, an insulating layer 323, a conductive layer 324, a pair of conductive layers 325, an insulating layer 326, and a conductive layer 327.

[0422] Substrate 331 corresponds to substrate 291 in Figures 10(A) and 10(B). The laminated structure from substrate 331 to insulating layer 255 corresponds to layer 401 containing the transistor in Embodiment 1. An insulating substrate or a semiconductor substrate can be used as substrate 331.

[0423] An insulating layer 332 is provided on the substrate 331. The insulating layer 332 functions as a barrier layer that prevents impurities such as water or hydrogen from diffusing from the substrate 331 to the transistor 320, and prevents oxygen from detaching from the semiconductor layer 321 to the insulating layer 332. As the insulating layer 332, for example, a film that is less susceptible to hydrogen or oxygen diffusion than a silicon oxide film can be used, such as an aluminum oxide film, a hafnium oxide film, or a silicon nitride film.

[0424] A conductive layer 327 is provided on an insulating layer 332, and an insulating layer 326 is provided covering the conductive layer 327. The conductive layer 327 functions as the first gate electrode of the transistor 320, and a portion of the insulating layer 326 functions as the first gate insulating layer. It is preferable to use an oxide insulating film, such as a silicon oxide film, for at least the portion of the insulating layer 326 that is in contact with the semiconductor layer 321. It is preferable that the upper surface of the insulating layer 326 is flattened.

[0425] The semiconductor layer 321 is provided on the insulating layer 326. Preferably, the semiconductor layer 321 has a metal oxide (also called an oxide semiconductor) film having semiconductor properties. Details of materials suitable for use in the semiconductor layer 321 will be described later.

[0426] A pair of conductive layers 325 are provided in contact with the semiconductor layer 321 and function as source and drain electrodes.

[0427] Furthermore, an insulating layer 328 is provided covering the top and side surfaces of the pair of conductive layers 325, as well as the side surfaces of the semiconductor layer 321, and an insulating layer 264 is provided on the insulating layer 328. The insulating layer 328 functions as a barrier layer to prevent impurities such as water or hydrogen from diffusing into the semiconductor layer 321 from the insulating layer 264, etc., and to prevent oxygen from detaching from the semiconductor layer 321. As the insulating layer 328, an insulating film similar to that of the insulating layer 332 can be used.

[0428] An opening is provided in the insulating layer 328 and the insulating layer 264 that reaches the semiconductor layer 321. Inside this opening, the insulating layer 323 and the conductive layer 324 are embedded, in contact with the sides of the insulating layer 264, the insulating layer 328, and the conductive layer 325, as well as the upper surface of the semiconductor layer 321. The conductive layer 324 functions as a second gate electrode, and the insulating layer 323 functions as a second gate insulating layer.

[0429] The upper surfaces of the conductive layer 324, the insulating layer 323, and the insulating layer 264 are flattened so that their heights are roughly the same, and the insulating layer 329 and insulating layer 265 are provided covering them.

[0430] Insulating layers 264 and 265 function as interlayer insulating layers. Insulating layer 329 functions as a barrier layer to prevent impurities such as water or hydrogen from diffusing into the transistor 320 from insulating layer 265, etc. As insulating layer 329, an insulating film similar to that used for insulating layers 328 and 332 can be used.

[0431] A plug 274, which is electrically connected to one of the pair of conductive layers 325, is provided so as to be embedded in the insulating layers 265, 329, and 264. Here, it is preferable that the plug 274 has a conductive layer 274a that covers the sides of the openings of the insulating layers 265, 329, 264, and 328, and a part of the upper surface of the conductive layer 325, and a conductive layer 274b that is in contact with the upper surface of the conductive layer 274a. In this case, it is preferable to use a conductive material that does not easily allow hydrogen and oxygen to diffuse as the conductive layer 274a.

[0432] The configuration from the insulating layer 254 to the substrate 420 in the light-emitting device 400D is the same as that of the light-emitting device 400C.

[0433] [Light-emitting device 400E] The light-emitting device 400E shown in Figure 13 has a configuration in which a transistor 310 with a channel formed on a substrate 301 and a transistor 320 containing a metal oxide in the semiconductor layer where the channel is formed are stacked. Note that parts that are the same as those of light-emitting devices 400C and 400D may be omitted from the explanation.

[0434] An insulating layer 261 is provided covering the transistor 310, and a conductive layer 251 is provided on the insulating layer 261. An insulating layer 262 is provided covering the conductive layer 251, and a conductive layer 252 is provided on the insulating layer 262. The conductive layers 251 and 252 each function as wiring. An insulating layer 263 and an insulating layer 332 are provided covering the conductive layer 252, and a transistor 320 is provided on the insulating layer 332. An insulating layer 265 is provided covering the transistor 320, and a capacitor 240 is provided on the insulating layer 265. The capacitor 240 and the transistor 320 are electrically connected by a plug 274.

[0435] Transistor 320 can be used as a transistor constituting a pixel circuit. Transistor 310 can also be used as a transistor constituting a pixel circuit, or as a transistor constituting a drive circuit (gate line drive circuit, source line drive circuit) for driving the pixel circuit. Furthermore, transistors 310 and 320 can be used as transistors constituting various circuits such as arithmetic circuits or memory circuits.

[0436] This configuration allows for the formation of not only pixel circuits but also drive circuits directly beneath the light-emitting device, making it possible to miniaturize the display device compared to cases where the drive circuits are located around the display area.

[0437] The configuration examples illustrated in this embodiment, and the corresponding drawings, etc., can be appropriately combined with other configuration examples or drawings, etc., at least in part.

[0438] This embodiment can be implemented in appropriate combination with other embodiments described herein, at least in part.

[0439] (Embodiment 7) This embodiment describes a high-resolution display device.

[0440] [Example of pixel circuit configuration] The following describes examples of pixels suitable for high-resolution display devices and their arrangement methods.

[0441] Figure 14 shows an example of a circuit diagram of a pixel unit 70. The pixel unit 70 consists of two pixels (pixel 70a and pixel 70b). Wirings 51a, 51b, 52a, 52b, 52c, 52d, 53a, 53b, 53c, etc. are connected to the pixel unit 70.

[0442] Pixel 70a has sub-pixels 71a, 72a, and 73a. Pixel 70b has sub-pixels 71b, 72b, and 73b. Sub-pixels 71a, 72a, and 73a each have pixel circuits 41a, 42a, and 43a, respectively. Sub-pixels 71b, 72b, and 73b each have pixel circuits 41b, 42b, and 43b, respectively.

[0443] Each sub-pixel has a pixel circuit and a display element 60. For example, sub-pixel 71a has a pixel circuit 41a and a display element 60. Here, we show the case where an emissive device such as an organic EL element is used as the display element 60.

[0444] Wires 51a and 51b each function as gate lines. Wires 52a, 52b, 52c, and 52d each function as signal lines (also called data lines). Wires 53a, 53b, and 53c also have the function of supplying potential to the display element 60.

[0445] Pixel circuit 41a is electrically connected to wiring 51a, wiring 52a, and wiring 53a. Pixel circuit 42a is electrically connected to wiring 51b, wiring 52d, and wiring 53a. Pixel circuit 43a is electrically connected to wiring 51a, wiring 52b, and wiring 53b. Pixel circuit 41b is electrically connected to wiring 51b, wiring 52a, and wiring 53b. Pixel circuit 42b is electrically connected to wiring 51a, wiring 52c, and wiring 53c. Pixel circuit 43b is electrically connected to wiring 51b, wiring 52b, and wiring 53c.

[0446] As shown in Figure 14, by configuring each pixel to have two gate lines connected, the number of source lines can be halved compared to a stripe arrangement. This makes it possible to reduce the number of terminals on the IC used as the source drive circuit by half, thereby reducing the number of components.

[0447] Furthermore, it is preferable to configure a single wiring that functions as a signal line to connect pixel circuits corresponding to the same color. For example, when supplying a signal with adjusted potential to the wiring in order to correct variations in brightness between pixels, the correction value may differ significantly for each color. Therefore, by making all the pixel circuits connected to a single signal line pixel circuits corresponding to the same color, correction can be made easier.

[0448] Each pixel circuit also includes a transistor 61, a transistor 62, and a capacitive element 63. For example, in pixel circuit 41a, the gate of transistor 61 is electrically connected to wiring 51a, one of its source or drain is electrically connected to wiring 52a, and the other of its source or drain is electrically connected to the gate of transistor 62 and one electrode of capacitive element 63. The source or drain of transistor 62 is electrically connected to one electrode of display element 60, and the other of its source or drain is electrically connected to the other electrode of capacitive element 63 and wiring 53a. The other electrode of display element 60 is electrically connected to wiring to which a potential V1 is applied.

[0449] Furthermore, the other pixel circuits have the same configuration as pixel circuit 41a, except that the wiring connected to the gate of transistor 61, the wiring connected to either the source or drain of transistor 61, and the wiring connected to the other electrode of capacitive element 63 are different, as shown in Figure 14.

[0450] In Figure 14, transistor 61 functions as a selector transistor. Transistor 62 is connected in series with the display element 60 and has the function of controlling the current flowing through the display element 60. Capacitive element 63 has the function of maintaining the potential of the node to which the gate of transistor 62 is connected. Note that if the leakage current of transistor 61 in the off state and the leakage current through the gate of transistor 62 are extremely small, it may not be necessary to intentionally provide the capacitive element 63.

[0451] Here, as shown in Figure 14, it is preferable that the transistor 62 has a configuration in which an electrically connected first gate and a second gate are respectively provided. By having such a configuration with two gates, the current that the transistor 62 can supply can be increased. This is particularly preferable in high-definition display devices because it allows the current to be increased without increasing the size of the transistor 62, especially the channel width.

[0452] Furthermore, transistor 62 may have a single gate. This configuration eliminates the need for the process of forming the second gate, thus simplifying the process compared to the above. Also, transistor 61 may have two gates. This configuration allows for a reduction in the size of each transistor. Additionally, the first and second gates of each transistor can be electrically connected. Alternatively, one gate may be electrically connected to a different wiring. In this case, the threshold voltage of the transistor can be controlled by varying the potential applied to the wiring.

[0453] Furthermore, of the pair of electrodes of the display element 60, the electrode electrically connected to the transistor 62 corresponds to the pixel electrode. Here, Figure 14 shows a configuration in which the electrode electrically connected to the transistor 62 of the display element 60 is the cathode, and the electrode on the opposite side is the anode. Such a configuration is particularly effective when the transistor 62 is an n-channel type transistor. That is, when the transistor 62 is in the ON state, the potential supplied by the wiring 53a becomes the source potential, so the current flowing through the transistor 62 can be kept constant regardless of variations or fluctuations in the resistance of the display element 60. Alternatively, a p-channel type transistor may be used as the transistor in the pixel circuit.

[0454] (Embodiment 8) This embodiment describes metal oxides (also called oxide semiconductors) that can be used in the OS transistor described in the above embodiment.

[0455] The metal oxide preferably contains at least indium or zinc. It is particularly preferable that it contains indium and zinc. In addition, it is preferable that it contains aluminum, gallium, yttrium, tin, etc. It may also contain one or more selected from boron, silicon, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, magnesium, cobalt, etc.

[0456] Furthermore, metal oxides can be formed by methods such as sputtering, chemical vapor deposition (CVD) methods including metal-organic chemical vapor deposition (MOCVD), or atomic layer deposition (ALD).

[0457] <Classification of crystal structures> Examples of crystalline structures for oxide semiconductors include amorphous (including completely amorphous), CAAC (c-axis-aligned crystalline), nc (nanocrystalline), CAC (cloud-aligned composite), single crystal, and polycrystal.

[0458] The crystal structure of a film or substrate can be evaluated using X-ray diffraction (XRD) spectroscopy. For example, it can be evaluated using the XRD spectrum obtained by GIXD (Grazing-Incidence XRD) measurement. The GIXD method is also known as the thin-film method or the Seemann-Bohlin method.

[0459] For example, in a quartz glass substrate, the peak shape of the XRD spectrum is nearly symmetrical. On the other hand, in an IGZO film with a crystalline structure, the peak shape of the XRD spectrum is asymmetrical. The asymmetrical shape of the XRD spectrum peak clearly indicates the presence of crystals in the film or substrate. In other words, if the peak shape of the XRD spectrum is not symmetrical, the film or substrate cannot be said to be in an amorphous state.

[0460] Furthermore, the crystalline structure of a film or substrate can be evaluated by the diffraction pattern (also called the nano-beam electron diffraction pattern) observed using nano-beam electron diffraction (NBED). For example, a halo is observed in the diffraction pattern of a quartz glass substrate, confirming that the quartz glass is in an amorphous state. However, in the diffraction pattern of an IGZO film deposited at room temperature, a spot-like pattern is observed instead of a halo. Therefore, it is presumed that an IGZO film deposited at room temperature is in an intermediate state, neither crystalline nor amorphous, and cannot be concluded to be in an amorphous state.

[0461] <<Oxide semiconductor structure>> It should be noted that oxide semiconductors may be classified differently from those described above when considering their structure. For example, oxide semiconductors can be divided into single-crystal oxide semiconductors and other non-single-crystal oxide semiconductors. Examples of non-single-crystal oxide semiconductors include the aforementioned CAAC-OS and nc-OS. Non-single-crystal oxide semiconductors also include polycrystalline oxide semiconductors, pseudo-amorphous oxide semiconductors (a-like OS), and amorphous oxide semiconductors.

[0462] Here, we will explain the details of the CAAC-OS, nc-OS, and a-like OS mentioned above.

[0463] [CAAC-OS] CAAC-OS is an oxide semiconductor having multiple crystalline regions, the c-axis of which is oriented in a specific direction. This specific direction is the thickness direction of the CAAC-OS film, the normal direction to the surface on which the CAAC-OS film is formed, or the normal direction to the surface of the CAAC-OS film. A crystalline region is a region with periodic atomic arrangement. If we consider the atomic arrangement as a lattice arrangement, then a crystalline region is also a region with a aligned lattice arrangement. Furthermore, CAAC-OS has regions where multiple crystalline regions are connected in the ab-plane direction, and these regions may exhibit distortion. Distortion refers to a point in the connected region where the orientation of the lattice arrangement changes between a region with a aligned lattice arrangement and another region with a aligned lattice arrangement. In short, CAAC-OS is an oxide semiconductor that is c-axis oriented and does not exhibit clear orientation in the ab-plane direction.

[0464] Each of the multiple crystalline regions described above is composed of one or more minute crystals (crystals with a maximum diameter of less than 10 nm). When a crystalline region is composed of a single minute crystal, the maximum diameter of that crystalline region is less than 10 nm. When a crystalline region is composed of many minute crystals, the size of that crystalline region may be around several tens of nanometers.

[0465] Furthermore, in In-M-Zn oxides (where element M is one or more elements selected from aluminum, gallium, yttrium, tin, titanium, etc.), CAAC-OS tends to have a layered crystalline structure (also called a layered structure) consisting of layers containing indium (In) and oxygen (hereinafter referred to as the In layer) and layers containing element M, zinc (Zn), and oxygen (hereinafter referred to as the (M,Zn) layer). Note that indium and element M are mutually substitutable. Therefore, the (M,Zn) layer may contain indium. Also, the In layer may contain element M. Also, the In layer may contain Zn. This layered structure can be observed, for example, as a lattice image in high-resolution TEM (Transmission Electron Microscope) images.

[0466] When structural analysis of a CAAC-OS film is performed using an XRD instrument, for example, out-of-plane XRD measurements using θ / 2θ scanning show a peak indicating c-axis orientation at 2θ = 31° or nearby. Note that the position of the c-axis orientation peak (value of 2θ) may vary depending on the type and composition of the metal elements constituting the CAAC-OS.

[0467] Furthermore, for example, multiple bright spots are observed in the electron diffraction pattern of a CAAC-OS film. These spots are observed at point-symmetric positions with respect to the incident electron beam spot (also called the direct spot) that passed through the sample.

[0468] When the crystal region is observed from the specific direction described above, the lattice arrangement within that crystal region is based on a hexagonal lattice, but the unit cell is not necessarily a regular hexagon and may be non-regular hexagonal. Furthermore, the strain may have lattice arrangements such as pentagons or heptagons. Moreover, in CAAC-OS, clear grain boundaries cannot be observed even near the strain. In other words, it can be seen that the formation of grain boundaries is suppressed by the strain in the lattice arrangement. This is thought to be because CAAC-OS can tolerate strain due to factors such as the non-dense arrangement of oxygen atoms in the ab-plane direction and the change in interatomic bond distances due to the substitution of metal atoms.

[0469] A crystal structure in which clear grain boundaries are observed is called a polycrystal. Grain boundaries act as recombination centers, trapping carriers and potentially causing a decrease in transistor on-current and field-effect mobility. Therefore, CAAC-OS, in which clear grain boundaries are not observed, is one of the crystalline oxides with a suitable crystal structure for the semiconductor layer of a transistor. In addition, a structure containing Zn is preferred for the composition of CAAC-OS. For example, In-Zn oxide and In-Ga-Zn oxide are preferred because they suppress the generation of grain boundaries more than In oxide.

[0470] CAAC-OS is an oxide semiconductor with high crystallinity and no clearly defined grain boundaries. Therefore, CAAC-OS is less susceptible to the decrease in electron mobility caused by grain boundaries. Furthermore, since the crystallinity of oxide semiconductors can decrease due to the inclusion of impurities and the generation of defects, CAAC-OS can be said to be an oxide semiconductor with few impurities and defects (such as oxygen vacancies). Consequently, oxide semiconductors containing CAAC-OS have stable physical properties. Therefore, oxide semiconductors containing CAAC-OS are heat resistant and highly reliable. In addition, CAAC-OS is stable even at high temperatures (so-called thermal budget) during the manufacturing process. Therefore, using CAAC-OS in OS transistors allows for greater flexibility in the manufacturing process.

[0471] [nc-OS] nc-OS exhibits periodicity in atomic arrangement in minute regions (e.g., regions between 1 nm and 10 nm, particularly between 1 nm and 3 nm). In other words, nc-OS contains minute crystals. These minute crystals are also called nanocrystals because their size is, for example, between 1 nm and 10 nm, particularly between 1 nm and 3 nm. Furthermore, nc-OS shows no regularity in crystal orientation between different nanocrystals. Therefore, no orientation is observed throughout the film. Consequently, depending on the analytical method, nc-OS may be indistinguishable from a-like OS or amorphous oxide semiconductors. For example, when structural analysis of an nc-OS film is performed using an XRD instrument, no peaks indicating crystallinity are detected in out-of-plane XRD measurements using θ / 2θ scanning. Also, when electron diffraction (also called limited-field electron diffraction) is performed on an nc-OS film using an electron beam with a probe diameter larger than that of the nanocrystals (e.g., 50 nm or larger), a diffraction pattern resembling a halo pattern is observed. On the other hand, when electron diffraction (also called nanobeam electron diffraction) is performed on an nc-OS film using an electron beam with a probe diameter close to or smaller than the size of the nanocrystal (for example, 1 nm to 30 nm), an electron diffraction pattern may be obtained in which multiple spots are observed within a ring-shaped region centered on a direct spot.

[0472] [a-like OS] a-like OS is an oxide semiconductor having a structure between nc-OS and amorphous oxide semiconductors. a-like OS has porous or low-density regions. That is, a-like OS has lower crystallinity compared to nc-OS and CAAC-OS. Also, a-like OS has a higher hydrogen concentration in the film compared to nc-OS and CAAC-OS.

[0473] <<Oxide Semiconductor Composition>> Next, we will explain the details of CAC-OS mentioned above. Note that CAC-OS refers to the material composition.

[0474] [CAC-OS] CAC-OS is a material composition in which, for example, the elements constituting the metal oxide are unevenly distributed in sizes of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or close to that size. In the following, a state in which one or more metal elements are unevenly distributed in a metal oxide, and the regions containing these metal elements are mixed in sizes of 0.5 nm to 10 nm, preferably 1 nm to 3 nm, or close to that size, is also referred to as a mosaic or patchy state.

[0475] Furthermore, CAC-OS is a composite metal oxide having a mosaic-like structure formed by the separation of the material into a first region and a second region, with the first region distributed within the film (hereinafter also referred to as a cloud-like structure). In other words, CAC-OS is a composite metal oxide having a structure in which the first region and the second region are mixed.

[0476] Here, the atomic ratios of In, Ga, and Zn to the metal elements constituting the CAC-OS in In-Ga-Zn oxide are denoted as [In], [Ga], and [Zn], respectively. For example, in the CAC-OS of In-Ga-Zn oxide, the first region is the region where [In] is greater than the [In] in the composition of the CAC-OS film. The second region is the region where [Ga] is greater than the [Ga] in the composition of the CAC-OS film. Alternatively, for example, the first region is the region where [In] is greater than the [In] in the second region, and [Ga] is smaller than the [Ga] in the second region. The second region is the region where [Ga] is greater than the [Ga] in the first region, and [In] is smaller than the [In] in the first region.

[0477] Specifically, the first region described above is a region whose main components are indium oxide, indium zinc oxide, etc. The second region described above is a region whose main components are gallium oxide, gallium zinc oxide, etc. In other words, the first region can be rephrased as a region whose main component is In. Similarly, the second region can be rephrased as a region whose main component is Ga.

[0478] Furthermore, a clear boundary may not be observed between the first region and the second region described above.

[0479] Furthermore, CAC-OS in In-Ga-Zn oxide refers to a material composition containing In, Ga, Zn, and O, in which regions with Ga as the main component and regions with In as the main component are arranged in a mosaic-like manner, with these regions existing randomly. Therefore, it is presumed that CAC-OS has a structure in which metal elements are unevenly distributed.

[0480] CAC-OS can be formed, for example, by sputtering under conditions where the substrate is not heated. When forming CAC-OS by sputtering, one or more gases selected from inert gases (typically argon), oxygen gas, and nitrogen gas may be used as the film-forming gas. Furthermore, it is preferable that the ratio of the oxygen gas flow rate to the total flow rate of the film-forming gas during film formation be as low as possible. For example, it is preferable that the ratio of the oxygen gas flow rate to the total flow rate of the film-forming gas during film formation be 0% or more and less than 30%, preferably 0% or more and 10% or less.

[0481] Furthermore, for example, in the case of CAC-OS in In-Ga-Zn oxide, EDX mapping obtained using energy dispersive X-ray spectroscopy (EDX) confirms that it has a structure in which regions mainly composed of In (first region) and regions mainly composed of Ga (second region) are unevenly distributed and mixed.

[0482] Here, the first region is a region with higher conductivity compared to the second region. In other words, the conductivity of the metal oxide is exhibited when carriers flow through the first region. Therefore, a high field-effect mobility (μ) can be achieved when the first region is distributed in a cloud-like manner within the metal oxide.

[0483] On the other hand, the second region is a region with higher insulating properties compared to the first region. In other words, the distribution of the second region within the metal oxide can suppress leakage current.

[0484] Therefore, when CAC-OS is used in a transistor, the conductivity due to the first region and the insulation due to the second region work complementaryly to give CAC-OS a switching function (on / off function). In other words, CAC-OS has conductive function in part of the material, insulating function in part of the material, and semiconductor function as a whole. By separating the conductive function and the insulating function, both functions can be maximized. Therefore, by using CAC-OS in a transistor, a high on-current (I on ), high field-effect mobility (μ), and good switching operation can be achieved.

[0485] Furthermore, transistors using CAC-OS offer high reliability. Therefore, CAC-OS is ideal for various semiconductor devices, including display devices.

[0486] Oxide semiconductors can take on diverse structures, each possessing different properties. One embodiment of the present invention may include two or more of the following: amorphous oxide semiconductors, polycrystalline oxide semiconductors, a-like OS, CAC-OS, nc-OS, and CAAC-OS.

[0487] <Transistors containing oxide semiconductors> Next, we will explain the case where the above oxide semiconductor is used in a transistor.

[0488] By using the above-mentioned oxide semiconductor in transistors, it is possible to realize transistors with high field-effect mobility. Furthermore, it is possible to realize highly reliable transistors.

[0489] It is preferable to use an oxide semiconductor with a low carrier concentration for the transistor. For example, the carrier concentration of an oxide semiconductor is 1 × 10⁻⁶. 17 cm -3 The following is preferably 1 × 10 15 cm -3 More preferably 1 × 10 13 cm -3More preferably 1 × 10 11 cm -3 More preferably 1 × 10 10 cm -3 It is less than 1 × 10 -9 cm -3 This concludes the explanation. Furthermore, when lowering the carrier concentration of an oxide semiconductor film, the impurity concentration in the oxide semiconductor film should be lowered to reduce the defect level density. In this specification, a low impurity concentration and low defect level density are referred to as high-purity intrinsic or substantially high-purity intrinsic. Note that oxide semiconductors with low carrier concentrations are sometimes referred to as high-purity intrinsic or substantially high-purity intrinsic oxide semiconductors.

[0490] Furthermore, oxide semiconductor films that are highly intrinsic or substantially highly intrinsic may have a low trap level density due to their low defect level density.

[0491] Furthermore, charges trapped in the trap levels of oxide semiconductors can take a long time to disappear, sometimes behaving like fixed charges. Therefore, transistors in which channel formation regions are formed in oxide semiconductors with a high trap level density may exhibit unstable electrical properties.

[0492] Therefore, reducing the impurity concentration in the oxide semiconductor is effective in stabilizing the electrical characteristics of the transistor. Furthermore, in order to reduce the impurity concentration in the oxide semiconductor, it is preferable to also reduce the impurity concentration in adjacent films. Examples of impurities include hydrogen, nitrogen, alkali metals, alkaline earth metals, iron, nickel, and silicon.

[0493] <Impurities> Here, we will explain the effects of various impurities in oxide semiconductors.

[0494] In oxide semiconductors, the presence of silicon or carbon, which are Group 14 elements, leads to the formation of defect levels in the oxide semiconductor. Therefore, the concentration of silicon or carbon in the oxide semiconductor and the concentration of silicon or carbon near the interface with the oxide semiconductor (concentration obtained by secondary ion mass spectrometry (SIMS)) are compared by 2 × 10⁻⁶. 18 atoms / cm 3 The following is preferably 2 × 10 17 atoms / cm 3 The following applies:

[0495] Furthermore, if an oxide semiconductor contains alkali metals or alkaline earth metals, it may form defect levels and generate carriers. Therefore, transistors using oxide semiconductors containing alkali metals or alkaline earth metals tend to exhibit normally-on characteristics. For this reason, the concentration of alkali metals or alkaline earth metals in the oxide semiconductor obtained by SIMS should be set to 1 × 10⁻⁶. 18 atoms / cm 3 The following is preferably 2 × 10 16 atoms / cm 3 Do the following:

[0496] Furthermore, in oxide semiconductors, the presence of nitrogen generates electrons, which act as carriers, increasing the carrier concentration and making it easier for the semiconductor to become n-type. As a result, transistors using oxide semiconductors containing nitrogen tend to exhibit normally-on characteristics. Alternatively, the presence of nitrogen in oxide semiconductors can lead to the formation of trap levels. As a result, the electrical properties of the transistor may become unstable. For this reason, the nitrogen concentration in oxide semiconductors obtained by SIMS should be set to 5 × 10⁻⁶. 19 atoms / cm 3 Less than 5 × 10 18 atoms / cm 3 More preferably 1 × 10 18 atoms / cm 3 More preferably 5 × 10 17 atoms / cm 3 Do the following:

[0497] Furthermore, hydrogen contained in oxide semiconductors can react with oxygen bonded to metal atoms to form water, potentially creating oxygen vacancies. Hydrogen can then fill these vacancies, generating electrons, which act as carriers. Additionally, some of the hydrogen can combine with oxygen bonded to metal atoms to generate electrons. Therefore, transistors using oxide semiconductors containing hydrogen tend to exhibit normally-on characteristics. For this reason, it is preferable to reduce the hydrogen content in oxide semiconductors as much as possible. Specifically, in oxide semiconductors, the hydrogen concentration obtained by SIMS should be 1 × 10⁻⁶. 20 atoms / cm 3 Less than 1 × 10 19 atoms / cm 3 Less than 5x10 18 atoms / cm 3 Less than 1 × 10 18 atoms / cm 3 Make it less than.

[0498] By using an oxide semiconductor with sufficiently reduced impurities in the channel formation region of a transistor, stable electrical characteristics can be provided.

[0499] This embodiment can be implemented in appropriate combination with other embodiments described herein, at least in part.

[0500] (Embodiment 9) In this embodiment, an electronic device according to one aspect of the present invention will be described with reference to Figures 15 to 18.

[0501] The electronic device of this embodiment has a display device according to one aspect of the present invention. The display device according to one aspect of the present invention is easily made high-definition, high-resolution, and large-scale. Therefore, the display device according to one aspect of the present invention can be used in the display units of various electronic devices.

[0502] Furthermore, since the display device according to one aspect of the present invention can be manufactured at a low cost, the manufacturing cost of electronic devices can be reduced.

[0503] Examples of electronic devices include television sets, desktop or notebook personal computers, computer monitors, digital signage, and large game machines such as pachinko machines, as well as other electronic devices with relatively large screens, digital cameras, digital video cameras, digital photo frames, mobile phones, portable game consoles, personal digital assistants, and audio playback devices.

[0504] In particular, a display device according to one aspect of the present invention can be used suitably in electronic devices having a relatively small display area because it can increase resolution. Examples of such electronic devices include information terminals (wearable devices) such as wristwatches and bracelets, as well as wearable devices that can be worn on the head, such as VR devices such as head-mounted displays and AR devices such as glasses. Wearable devices also include devices for SR and MR.

[0505] A display device according to one aspect of the present invention preferably has an extremely high resolution such as HD (1280 x 720 pixels), FHD (1920 x 1080 pixels), WQHD (2560 x 1440 pixels), WQXGA (2560 x 1600 pixels), 4K2K (3840 x 2160 pixels), or 8K4K (7680 x 4320 pixels). In particular, a resolution of 4K2K, 8K4K, or higher is preferred. Furthermore, the pixel density (resolution) of the display device according to one aspect of the present invention is preferably 300 ppi or more, more preferably 500 ppi or more, more preferably 1000 ppi or more, more preferably 2000 ppi or more, more preferably 3000 ppi or more, more preferably 5000 ppi or more, and even more preferably 7000 ppi or more. By using display devices with such high resolution or high detail, it becomes possible to enhance the sense of presence and depth in personal electronic devices such as portable or home-use devices.

[0506] The electronic device of this embodiment can be incorporated along the curved surfaces of the interior or exterior walls of a house or building, or the interior or exterior of an automobile.

[0507] The electronic device in this embodiment may have an antenna. By receiving signals with the antenna, the display unit can display images and information. Furthermore, if the electronic device has an antenna and a secondary battery, the antenna may be used for contactless power transmission.

[0508] The electronic device of this embodiment may have sensors (including those with the function of detecting, detecting, or measuring force, displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substances, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared radiation).

[0509] The electronic device of this embodiment can have a variety of functions. For example, it can have a function to display various information (still images, videos, text images, etc.) on the display unit, a touch panel function, a function to display a calendar, date or time, a function to execute various software (programs), a wireless communication function, a function to read programs or data recorded on a recording medium, and so on.

[0510] The electronic device 6500 shown in Figure 15(A) is a portable information terminal that can be used as a smartphone.

[0511] The electronic device 6500 includes a housing 6501, a display unit 6502, a power button 6503, a button 6504, a speaker 6505, a microphone 6506, a camera 6507, and a light source 6508, etc. The display unit 6502 has a touch panel function.

[0512] A display device according to one aspect of the present invention can be applied to the display unit 6502.

[0513] Figure 15(B) is a schematic cross-sectional view of the housing 6501 including the end on the microphone 6506 side.

[0514] A light-transmitting protective member 6510 is provided on the display side of the housing 6501, and the display panel 6511, optical member 6512, touch sensor panel 6513, printed circuit board 6517, battery 6518, etc. are arranged in the space enclosed by the housing 6501 and the protective member 6510.

[0515] The protective member 6510 is fixed to the display panel 6511, the optical member 6512, and the touch sensor panel 6513 by an adhesive layer (not shown).

[0516] In the area outside the display unit 6502, a portion of the display panel 6511 is folded back, and the FPC 6515 is connected to this folded portion. IC 6516 is mounted on the FPC 6515. The FPC 6515 is connected to terminals provided on the printed circuit board 6517.

[0517] A flexible display (a display device with flexibility) according to one embodiment of the present invention can be applied to the display panel 6511. As a result, an extremely lightweight electronic device can be realized. Furthermore, because the display panel 6511 is extremely thin, a large-capacity battery 6518 can be installed while keeping the thickness of the electronic device low. In addition, by folding back a part of the display panel 6511 and placing the connection part with the FPC 6515 on the back of the pixel area, an electronic device with a narrow bezel can be realized.

[0518] Figure 16(A) shows an example of a television system. The television system 7100 has a display unit 7000 incorporated into a housing 7101. Here, the housing 7101 is shown supported by a stand 7103.

[0519] A display device according to one embodiment of the present invention can be applied to the display unit 7000.

[0520] The television device 7100 shown in Figure 16(A) can be operated using the operation switches on the housing 7101 and a separate remote control unit 7111. Alternatively, the display unit 7000 may be equipped with a touch sensor, and the television device 7100 can be operated by touching the display unit 7000 with a finger or the like. The remote control unit 7111 may have a display unit that displays information output from the remote control unit 7111. Channels and volume can be controlled and the image displayed on the display unit 7000 can be controlled using the operation keys or touch panel on the remote control unit 7111.

[0521] The television system 7100 is configured to include a receiver and a modem. The receiver can receive general television broadcasts. Furthermore, by connecting to a wired or wireless communication network via the modem, it is possible to perform one-way (from sender to receiver) or two-way (between sender and receiver, or between receivers, etc.) information communication.

[0522] Figure 16(B) shows an example of a notebook personal computer. The notebook personal computer 7200 has a casing 7211, a keyboard 7212, a pointing device 7213, an external connection port 7214, etc. A display unit 7000 is incorporated into the casing 7211.

[0523] A display device according to one embodiment of the present invention can be applied to the display unit 7000.

[0524] Figures 16(C) and 16(D) show examples of digital signage.

[0525] The digital signage 7300 shown in Figure 16(C) comprises a housing 7301, a display unit 7000, and a speaker 7303, etc. Furthermore, it may include LED lamps, operation keys (including a power switch or operation switch), connection terminals, various sensors, a microphone, etc.

[0526] Figure 16(D) shows a digital signage 7400 mounted on a cylindrical column 7401. The digital signage 7400 has a display unit 7000 that is provided along the curved surface of the column 7401.

[0527] In Figures 16(C) and 16(D), a display device according to one embodiment of the present invention can be applied to the display unit 7000.

[0528] The larger the display area 7000, the more information can be provided at once. Furthermore, a larger display area 7000 is more eye-catching, which can, for example, enhance the effectiveness of advertising.

[0529] Applying a touch panel to the display unit 7000 is preferable because it not only allows images or videos to be displayed on the display unit 7000, but also enables intuitive operation by the user. Furthermore, when used for purposes such as providing route information or traffic information, intuitive operation can enhance usability.

[0530] Furthermore, as shown in Figures 16(C) and 16(D), it is preferable that the digital signage 7300 or digital signage 7400 can be linked wirelessly with an information terminal 7311 or information terminal 7411 such as a smartphone owned by the user. For example, the advertising information displayed on the display unit 7000 can be displayed on the screen of the information terminal 7311 or information terminal 7411. Also, the display on the display unit 7000 can be switched by operating the information terminal 7311 or information terminal 7411.

[0531] Furthermore, the digital signage 7300 or digital signage 7400 can be used to run games using the screen of the information terminal 7311 or information terminal 7411 as the control device (controller). This allows a large number of users to participate in and enjoy the game simultaneously.

[0532] Figure 17(A) shows the external appearance of the Camera 8000 with the Viewfinder 8100 attached.

[0533] The camera 8000 includes a housing 8001, a display unit 8002, operation buttons 8003, a shutter button 8004, etc. A detachable lens 8006 is also attached to the camera 8000. The lens 8006 and the housing of the camera 8000 may be integrated into a single unit.

[0534] Camera 8000 can take an image by pressing the shutter button 8004 or by touching the display unit 8002, which functions as a touch panel.

[0535] The housing 8001 has a mount with electrodes, and in addition to the viewfinder 8100, a strobe device and the like can be connected to it.

[0536] The viewfinder 8100 includes a housing 8101, a display unit 8102, buttons 8103, etc.

[0537] The housing 8101 is attached to the camera 8000 by a mount that engages with the camera 8000's mount. The viewfinder 8100 can display images and other data received from the camera 8000 on the display unit 8102.

[0538] Button 8103 functions as a power button, etc.

[0539] A display device according to one embodiment of the present invention can be applied to the display unit 8002 of the camera 8000 and the display unit 8102 of the viewfinder 8100. The camera 8000 may also have a built-in viewfinder.

[0540] Figure 17(B) shows the external appearance of the head-mounted display 8200.

[0541] The head-mounted display 8200 includes a mounting section 8201, lenses 8202, a main unit 8203, a display unit 8204, a cable 8205, etc. The mounting section 8201 also has a built-in battery 8206.

[0542] Cable 8205 supplies power from battery 8206 to main unit 8203. Main unit 8203 is equipped with a wireless receiver and can display received video information on display unit 8204. In addition, main unit 8203 is equipped with a camera and can use information about the user's eyeball or eyelid movements as an input means.

[0543] Furthermore, the attachment unit 8201 may be provided with multiple electrodes at a position that touches the user, capable of detecting the current flowing in accordance with the user's eye movements, and may have a function to recognize the user's gaze. It may also have a function to monitor the user's pulse rate based on the current flowing through the electrodes. In addition, the attachment unit 8201 may have various sensors such as a temperature sensor, a pressure sensor, and an acceleration sensor, and may have a function to display the user's biometric information on the display unit 8204, or a function to change the image displayed on the display unit 8204 in accordance with the user's head movements.

[0544] A display device according to one aspect of the present invention can be applied to the display unit 8204.

[0545] Figures 17(C) to 17(E) show the external appearance of the head-mounted display 8300. The head-mounted display 8300 comprises a housing 8301, a display unit 8302, a band-shaped fixing device 8304, and a pair of lenses 8305.

[0546] The user can view the display on the display unit 8302 through the lens 8305. It is preferable to position the display unit 8302 in a curved shape, as this allows the user to experience a greater sense of presence. Furthermore, by viewing different images displayed in different areas of the display unit 8302 through the lens 8305, three-dimensional display using parallax can be performed. Note that the configuration is not limited to a single display unit 8302; two display units 8302 may be provided, with one display unit for each of the user's eyes.

[0547] A display device according to one embodiment of the present invention can be applied to the display unit 8302. The display device according to one embodiment of the present invention can also achieve extremely high resolution. For example, even when the display is magnified and viewed using the lens 8305 as shown in Figure 17(E), the pixels are difficult for the user to see. In other words, the display unit 8302 can be used to allow the user to view images with a high degree of realism.

[0548] Figure 17(F) shows the external appearance of a goggle-type head-mounted display 8400. The head-mounted display 8400 has a pair of housings 8401, a mounting part 8402, and a cushioning member 8403. A display unit 8404 and a lens 8405 are provided inside each of the pair of housings 8401. By displaying different images on the pair of display units 8404, a three-dimensional display using parallax can be performed.

[0549] The user can view the display unit 8404 through the lens 8405. The lens 8405 has a focus adjustment mechanism and its position can be adjusted according to the user's eyesight. The display unit 8404 is preferably a square or a horizontally elongated rectangle. This can enhance the sense of realism.

[0550] The mounting portion 8402 is preferably adjustable to the size of the user's face and has plasticity and elasticity to prevent it from slipping off. Furthermore, it is preferable that a part of the mounting portion 8402 has a vibration mechanism that functions as a bone conduction earphone. This eliminates the need for separate audio equipment such as earphones or speakers, allowing users to enjoy video and audio simply by wearing the device. The housing 8401 may also have a function to output audio data via wireless communication.

[0551] The mounting portion 8402 and the cushioning member 8403 are parts that come into contact with the user's face (forehead, cheeks, etc.). By ensuring that the cushioning member 8403 is in close contact with the user's face, light leakage can be prevented, thereby enhancing the sense of immersion. It is preferable to use a soft material for the cushioning member 8403 so that it adheres closely to the user's face when the user wears the head-mounted display 8400. For example, materials such as rubber, silicone rubber, urethane, and sponge can be used. Furthermore, if the surface of a sponge or similar material is covered with cloth, leather (genuine leather or synthetic leather), gaps are less likely to form between the user's face and the cushioning member 8403, effectively preventing light leakage. In addition, using such materials is preferable because it feels good against the skin and does not make the user feel cold when worn in cold seasons. It is preferable that the components that come into contact with the user's skin, such as the cushioning member 8403 or the mounting portion 8402, are removable, as this makes cleaning or replacement easier.

[0552] The electronic equipment shown in Figures 18(A) to 18(F) includes a housing 9000, a display unit 9001, a speaker 9003, operation keys 9005 (including a power switch or operation switch), connection terminals 9006, sensors 9007 (including functions for detecting, detecting, or measuring force, displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substances, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared radiation), a microphone 9008, etc.

[0553] The electronic devices shown in Figures 18(A) to 18(F) have various functions. For example, they may have functions to display various information (still images, videos, text images, etc.) on a display unit, a touch panel function, a function to display a calendar, date or time, a function to control processing by various software (programs), a wireless communication function, a function to read and process programs or data recorded on a recording medium, etc. However, the functions of electronic devices are not limited to these and can have various functions. Electronic devices may have multiple display units. Furthermore, electronic devices may be equipped with a camera, etc., and have functions to capture still images or videos and save them to a recording medium (external or built into the camera), a function to display the captured images on a display unit, etc.

[0554] A display device according to one embodiment of the present invention can be applied to the display unit 9001.

[0555] Details of the electronic equipment shown in Figures 18(A) to 18(F) will be explained below.

[0556] Figure 18(A) is a perspective view showing a personal digital assistant (PDA) 9101. The PDA 9101 can be used, for example, as a smartphone. The PDA 9101 may also be equipped with a speaker 9003, connection terminals 9006, sensors 9007, etc. The PDA 9101 can also display text and image information on multiple surfaces. Figure 18(A) shows an example where three icons 9050 are displayed. Information 9051, indicated by a dashed rectangle, can also be displayed on other surfaces of the display unit 9001. Examples of information 9051 include notifications of incoming emails, SNS messages, and phone calls, the subject of emails and SNS messages, the sender's name, date and time, battery level, and antenna signal strength. Alternatively, icons 9050 or the like may be displayed in the location where the information 9051 is displayed.

[0557] Figure 18(B) is a perspective view showing the personal digital assistant (PDA) 9102. The PDA 9102 has the function of displaying information on three or more sides of the display unit 9001. Here, an example is shown in which information 9052, information 9053, and information 9054 are displayed on different sides. For example, a user can check information 9053, which is displayed in a position that can be observed from above the PDA 9102, while the PDA 9102 is stored in the breast pocket of their clothing. The user can check the display without taking the PDA 9102 out of their pocket and decide, for example, whether or not to answer a call.

[0558] Figure 18(C) is a perspective view showing a wristwatch-type personal information terminal 9200. The personal information terminal 9200 can be used, for example, as a smartwatch (registered trademark). The display unit 9001 has a curved display surface, allowing it to display information along the curved surface. The personal information terminal 9200 can also be used for hands-free calls by communicating with, for example, a wireless communication headset. Furthermore, the personal information terminal 9200 can transmit data to other information terminals and be charged via the connection terminal 9006. Charging may be performed by wireless power supply.

[0559] Figures 18(D) to 18(F) are perspective views showing a foldable portable information terminal 9201. Figure 18(D) shows the portable information terminal 9201 in an unfolded state, Figure 18(F) shows it in a folded state, and Figure 18(E) shows a perspective view of the state in between Figures 18(D) and 18(F). The portable information terminal 9201 offers excellent portability in its folded state and excellent readability of the display due to its seamless, wide display area in its unfolded state. The display unit 9001 of the portable information terminal 9201 is supported by three housings 9000 connected by hinges 9055. For example, the display unit 9001 can be bent with a radius of curvature of 0.1 mm to 150 mm.

[0560] The configuration examples illustrated in this embodiment, and the corresponding drawings, etc., can be appropriately combined with other configuration examples or drawings, etc., at least in part.

[0561] This embodiment can be implemented in appropriate combination with other embodiments described herein, at least in part. [Examples]

[0562] This embodiment will describe in detail a light-emitting device according to one aspect of the present invention. The structural formulas of representative organic compounds used in this embodiment are shown below.

[0563] [ka]

[0564] [ka]

[0565] (Method for fabricating light-emitting device D1) As a reflective electrode, silver (Ag) was deposited to a thickness of 100 nm by sputtering, and then as a transparent electrode, indium tin oxide (ITSO) containing silicon oxide was deposited to a thickness of 10 nm by sputtering to form the first electrode 101. The electrode area was 4 mm². 2 The dimensions were set to (2mm x 2mm). The ITSO is a transparent electrode and functions as an anode. Furthermore, together with the reflective electrode mentioned above, it can be considered as the first electrode 101.

[0566] Next, as a pretreatment for forming a light-emitting device on the substrate, the substrate surface was washed with water, baked at 200°C for 1 hour, and then subjected to UV ozone treatment for 370 seconds.

[0567] Then, 10 -4 The substrate was introduced into a vacuum deposition apparatus where the internal pressure was reduced to approximately Pa. After vacuum firing at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, the substrate was allowed to cool for about 30 minutes.

[0568] Next, the substrate on which the first electrode 101 is formed is fixed to a substrate holder provided in a vacuum deposition apparatus so that the surface on which the first electrode 101 is formed faces downwards. Then, a hole injection layer 111 is formed on the first electrode 101 by co-depositing N-(1,1'-biphenyl-2-yl)-N-(9,9-dimethylfluoren-2-yl)-9,9'-spirobi[9H-fluoren]-2-amine (abbreviated as oFBiSF(2)), represented by the above structural formula (i), and an electron acceptor material (OCHD-003) containing fluorine with a molecular weight of 672, in a weight ratio of 1:0.04 (=oFBiSF(2):OCHD-003) to a thickness of 10 nm using a deposition method with resistance heating.

[0569] Next, oFBiSF(2) was deposited onto the hole injection layer 111 to a thickness of 120 nm to form a first hole transport layer. Subsequently, N-(3'',5',5''-tri-tert-butyl-1,1':3',1''-terphenyl-4-yl)-N-(4-cyclohexylphenyl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviated as mmtBumTPchPAF-04), represented by the above structural formula (I), was deposited to a thickness of 40 nm to create a second hole transport layer. The second hole transport layer also functions as an electron blocking layer.

[0570] Furthermore, on the second hole transport layer, there is 11-(4-[1,1'-biphenyl]-4-yl-6-phenyl-1,3,5-triazine-2-yl)-11,12-dihydro-12-phenyl-indoro[2,3-a]carbazole (abbreviated as BP-Icz(II)Tzn) represented by the above structural formula (ii), and 9-(2-naphthyl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviated as βNCCP) represented by the above structural formula (iii), and the above structure A light-emitting layer 113 was formed by co-depositing [2-d3-methyl-(2-pyridinyl-κN)benzofl[2,3-b]pyridine-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviated as Ir(ppy)2(mbfpypy-d3)), represented by formula (iv), in a weight ratio of 0.5:0.5:0.1 (=BP-Icz(II)Tzn:βNCCP:Ir(ppy)2(mbfpypy-d3)) to a film thickness of 40 nm.

[0571] Next, a hole-blocking layer was formed on the light-emitting layer 113 by depositing 6-(1,1'-biphenyl-3-yl)-4-[3,5-bis(9H-carbazole-9-yl)phenyl]-2-phenylpyrimidine (abbreviated as 6mBP-4Cz2PPm), represented by the above structural formula (v), to a thickness of 10 nm.

[0572] Subsequently, 2,4-bis[4-(1-naphthyl)phenyl]-6-[4-(pyridine-3yl)phenyl]pyrimidine (abbreviated as 2,4NP-6PyPPm2), represented by the above structural formula (vi), and 8-quinolinolato-lithium (abbreviated as Liq), represented by the above structural formula (vii), were co-deposited in a weight ratio of 0.5:0.5 (=2,4NP-6PyPPm2:Liq) to form an electron transport layer 114 with a film thickness of 25 nm.

[0573] After forming the electron transport layer 114, an electron injection layer 115 was formed by depositing lithium fluoride (LiF) at a volume ratio of 1 nm and a film thickness of 15 nm. Finally, the second electrode 102 was formed by co-depositing silver (Ag) and magnesium (Mg) at a volume ratio of 10:1 and a film thickness of 15 nm to fabricate the light-emitting device D1. The second electrode 102 is a semi-transmissive / semi-reflective electrode having both light-reflecting and light-transmitting functions, and the light-emitting device in this embodiment is a top-emission type element that extracts light from the second electrode 102. Furthermore, a cap layer was formed on the second electrode 102 by depositing 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), represented by the above structural formula (viii), at a volume ratio of 70 nm to improve extraction efficiency.

[0574] (Method for fabricating light-emitting device D2) Light-emitting device D2 was fabricated in the same manner as light-emitting device D1, except that the thickness of the first hole transport layer was set to 125 nm, and the second hole transport layer (electron blocking layer) was composed of N-3',5'-ditterybutyl-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 (II).

[0575] (Method for fabricating the light-emitting device D3) Light-emitting device D3 was fabricated in the same manner as light-emitting device D1, except that the thickness of the first hole transport layer was set to 125 nm, and the second hole transport layer (electron blocking layer) was composed of N-(3',5',-di-tert-butyl-1,1'-biphenyl-4-yl)-N-(9,9-dimethyl-9H-fluoren-4-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBuBiFF-02) represented by the above structural formula (III).

[0576] (Method for fabricating the light-emitting device D4) Light-emitting device D4 was fabricated in the same manner as light-emitting device D1, except that the thickness of the first hole transport layer was set to 125 nm, and the second hole transport layer (electron blocking layer) was composed of 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 (IV).

[0577] (Method for fabricating the light-emitting device D5) Light-emitting device D5 was fabricated in the same manner as light-emitting device D1, except that the thickness of the first hole transport layer was set to 125 nm, and the second hole transport layer (electron blocking layer) was composed of N-(1,1'-biphenyl-2-yl)-N-[(3',5'-di-tert-butyl)-1,1'-biphenyl-4-yl]-9,9-bis(4-tert-butylphenyl)-9H-fluoren-2-amine (abbreviation: mmtBuBioBitBu2FLP(2)) represented by the above structural formula (V).

[0578] (Method for fabricating the light-emitting device CD1) Light-emitting device CD1 was fabricated in the same manner as light-emitting device D1, except that the second hole transport layer (electron blocking layer) was composed of N-[4-(4-dibenzofuranyl)phenyl]-N-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-[1,1'-biphenyl]-4-amine (abbreviated as FrBBiFLP), represented by the above structural formula (VI).

[0579] (Method for fabricating the light-emitting device CD2) Light-emitting device CD2 was fabricated in the same manner as light-emitting device D1, except that the thickness of the first hole transport layer was set to 125 nm, and the second hole transport layer (electron blocking layer) was composed of 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 (VII).

[0580] The GSP_slope of the element structure and the materials used for the electron blocking layer of the above-mentioned light-emitting device is summarized in the table below.

[0581] [Table 3]

[0582] [Table 4]

[0583] Table 4 shows that light-emitting devices D1 to D5 are light-emitting devices that use a transport material with a GSP_slope of 20 or more in the electron block layer, while light-emitting devices CD1 and CD2 are light-emitting devices that use a transport material with a GSP_slope of 20 or less. It can also be considered that the electron block layer is part of the hole transport layer.

[0584] Furthermore, among the materials constituting the light-emitting layer, BP-Icz(II)Tzn had the lowest LUMO level, showing -2.99 eV. The LUMO levels of the electron blocking materials of light-emitting devices D1 to D5 were all at least 0.5 eV higher than -2.99 eV, indicating that light-emitting devices D1 to D5 have a configuration that provides sufficient electron blocking performance.

[0585] The above-mentioned light-emitting device was sealed on a glass substrate in a glove box under a nitrogen atmosphere to prevent exposure to the atmosphere (sealant was applied around the element, UV treatment was performed during sealing, and heat treatment was performed at 80°C for 1 hour). After this, the initial characteristics were measured. No special measures were taken to improve the extraction efficiency of the glass substrate on which the light-emitting device was fabricated.

[0586] Figure 19 shows the brightness-current density characteristics of each of the above light-emitting devices, Figure 20 shows the current efficiency-brightness characteristics, Figure 21 shows the brightness-voltage characteristics, Figure 22 shows the current density-voltage characteristics, Figure 23 shows the external quantum efficiency-brightness characteristics, Figure 24 shows the power efficiency-brightness characteristics, and Figure 25 shows the emission spectrum. Furthermore, the emission spectrum of each light-emitting device at 1000 cd / m² is shown. 2 Table 5 shows the main characteristics of the vicinity. Luminance, CIE chromaticity, and emission spectrum were measured using a spectroradiometer (Topcon SR-UL1R) at room temperature. The external quantum efficiency is a reference value calculated using the measured luminance and emission spectrum, assuming a Lambertsian light distribution pattern.

[0587] [Table 5]

[0588] From Figures 19 to 25 and Table 5, it was found that light-emitting devices D1 to D5, which use transport materials with a GSP_slope of 20 or more in the electron block layer, are light-emitting devices with good characteristics, such as lower driving voltage and higher luminous efficiency, compared to light-emitting devices CD1 and CD2, which use transport materials with a GSP_slope of 20 or less. [Examples]

[0589] This embodiment will describe in detail a light-emitting device according to one aspect of the present invention. The structural formulas of representative organic compounds used in this embodiment are shown below.

[0590] [ka]

[0591] [ka]

[0592] (Method for fabricating the light-emitting device D11) As a reflective electrode, silver (Ag) was deposited to a thickness of 100 nm by sputtering, and then as a transparent electrode, indium tin oxide (ITSO) containing silicon oxide was deposited to a thickness of 10 nm by sputtering to form the first electrode 101. The electrode area was 4 mm². 2 The dimensions were set to (2mm x 2mm). Note that ITSO is a transparent electrode and, together with the reflective electrode, can be considered as the first electrode 101.

[0593] Next, as a pretreatment for forming a light-emitting device on the substrate, the substrate surface was washed with water, baked at 200°C for 1 hour, and then subjected to UV ozone treatment for 370 seconds.

[0594] Then, 10 -4 The substrate was introduced into a vacuum deposition apparatus where the internal pressure was reduced to approximately Pa. After vacuum firing at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, the substrate was allowed to cool for about 30 minutes.

[0595] Next, the substrate on which the first electrode 101 is formed is fixed to a substrate holder provided in a vacuum deposition apparatus so that the surface on which the first electrode 101 is formed faces downwards. Then, a hole injection layer 111 is formed on the first electrode 101 by co-depositing N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviated as PCBBiF), represented by the above structural formula (viii), and an electron acceptor material (OCHD-003) containing fluorine with a molecular weight of 672, in a weight ratio of 1:0.04 (=PCBBiF:OCHD-003) to a thickness of 10 nm using a deposition method with resistance heating.

[0596] Next, PCBBiF was deposited on the hole injection layer 111 to a thickness of 115 nm to form the first hole transport layer 112. Then, N-2',4',6'-triter-butyl-1,1'-biphenyl-4-yl-N-(4-cyclohexylphenyl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviated as ch3BichPAF), represented by the above structural formula (VIII), was deposited to a thickness of 40 nm to form the second hole transport layer. The second hole transport layer also functions as an electron blocking layer.

[0597] Furthermore, on the second hole transport layer, there is 11-(4-[1,1'-biphenyl]-4-yl-6-phenyl-1,3,5-triazine-2-yl)-11,12-dihydro-12-phenyl-indoro[2,3-a]carbazole (abbreviated as BP-Icz(II)Tzn) represented by the above structural formula (ii), and 9-(2-naphthyl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviated as βNCCP) represented by the above structural formula (iii), and the above structure A light-emitting layer 113 was formed by co-depositing [2-d3-methyl-(2-pyridinyl-κN)benzofl[2,3-b]pyridine-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviated as Ir(ppy)2(mbfpypy-d3)), represented by formula (iv), in a weight ratio of 0.5:0.5:0.1 (=BP-Icz(II)Tzn:βNCCP:Ir(ppy)2(mbfpypy-d3)) to a film thickness of 40 nm.

[0598] Next, a hole-blocking layer was formed on the light-emitting layer 113 by depositing 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)-1,1'-biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviated as mFBPTzn), represented by the above structural formula (ix), to a thickness of 10 nm.

[0599] Subsequently, an electron transport layer 114 was formed by co-depositing 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenantrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviated as mPn-mDMePyPTzn), represented by the above structural formula (x), and 8-quinolinolato-lithium (abbreviated as Liq), represented by the above structural formula (vii), in a weight ratio of 0.5:0.5 (=mPn-mDMePyPTzn:Liq) with a film thickness of 25 nm.

[0600] After forming the electron transport layer 114, an electron injection layer 115 was formed by depositing lithium fluoride (LiF) at a volume ratio of 1 nm and a film thickness of 15 nm. Finally, the second electrode 102 was formed by co-depositing silver (Ag) and magnesium (Mg) at a volume ratio of 10:1 and a film thickness of 15 nm to fabricate the light-emitting device D11. The second electrode 102 is a semi-transmissive / semi-reflective electrode having both light-reflecting and light-transmitting functions, and the light-emitting device in this embodiment is a top-emission type element that extracts light from the second electrode 102. Furthermore, a cap layer was formed on the second electrode 102 by depositing 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), represented by the above structural formula (viii), at a volume ratio of 70 nm to improve extraction efficiency.

[0601] (Method for fabricating the light-emitting device D12) Light-emitting device D12 was fabricated in the same manner as light-emitting device D11, except that the thickness of the first hole transport layer was set to 110 nm, and the second hole transport layer (electron blocking layer) was composed of N-(3',5'-di-tert-butyl-1,1'-biphenyl-4-yl)-N-(5-cyclohexyl-1,1'-biphenyl-2-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBuBichoBiF) represented by the above structural formula (IX).

[0602] (Method for fabricating the light-emitting device D13) Light-emitting device D13 was fabricated in the same manner as light-emitting device D11, except that the thickness of the first hole transport layer was set to 110 nm, and the second hole transport layer (electron blocking layer) was composed of N-(3',5',-di-tert-butyl-1,1'-biphenyl-4-yl)-N-(9,9-dimethyl-9H-fluoren-4-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBuBiFF-02) represented by the above structural formula (III).

[0603] (Method for fabricating the light-emitting device D14) Light-emitting device D14 was fabricated in the same manner as light-emitting device D11, except that the thickness of the first hole transport layer was set to 110 nm, and the second hole transport layer (electron blocking layer) was composed of N-(1,1'-biphenyl-2-yl)-N-(3,3'',5',5''-tetra-tert-butyl-1,1':3',1''-terphenyl-5-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPoFBi-02) represented by the above structural formula (X).

[0604] (Method for fabricating the light-emitting device D15) Light-emitting device D15 was fabricated in the same manner as light-emitting device D11, except that the thickness of the first hole transport layer was set to 110 nm, and the second hole transport layer (electron blocking layer) was composed of N-[(3',5'-ditter-butyl)-1,1'-biphenyl-4-yl]-N-(4-cyclohexylphenyl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBuBichPAF) represented by the above structural formula (XI).

[0605] (Method for fabricating the light-emitting device D16) Light-emitting device D16 was fabricated in the same manner as light-emitting device D11, except that the thickness of the first hole transport layer was set to 120 nm, and the second hole transport layer (electron blocking layer) was composed of N-(1,1'-biphenyl-2-yl)-N-[(3',5'-di-tert-butyl)-1,1'-biphenyl-4-yl]-9,9-bis(4-tert-butylphenyl)-9H-fluoren-2-amine (abbreviation: mmtBuBioBitBu2FLP(2)) represented by the above structural formula (V).

[0606] (Method for fabricating the light-emitting device D17) Light-emitting device D17 was fabricated in the same manner as light-emitting device D11, except that the second hole transport layer (electron blocking layer) was composed of 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 (IV).

[0607] (Method for fabricating the light-emitting device CD11) Light-emitting device CD11 was fabricated in the same manner as light-emitting device D11, except that the thickness of the first hole transport layer was set to 110 nm, and the second hole transport layer (electron blocking layer) was composed of N-(1,1'-biphenyl-2-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spiro-bi[9H-fluoren]-4-amine (abbreviation: oFBiSF) represented by the above structural formula (XII).

[0608] (Method for fabricating the light-emitting device CD12) Light-emitting device CD12 was fabricated in the same manner as light-emitting device D11, except that the second hole transport layer (electron blocking layer) was composed of N-[2-(9,9-diphenyl-9H-fluoren-4-yl)phenyl]-N-(1,1'-biphenyl-4-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviated as FBiFLPB), represented by the above structural formula (XIII).

[0609] The GSP_slope of the element structure and the materials used for the electron blocking layer of the above-mentioned light-emitting device is summarized in the table below.

[0610] [Table 6]

[0611] [Table 7]

[0612] Table 7 shows that light-emitting devices D11 to D17 use a transport material with a GSP_slope of 20 or more in the electron block layer, while light-emitting devices CD11 and CD12 use a transport material with a GSP_slope of 20 or less. It can also be considered that the electron block layer is part of the hole transport layer.

[0613] Furthermore, among the materials constituting the light-emitting layer, BP-Icz(II)Tzn had the lowest LUMO level, showing -2.99 eV. The LUMO levels of the electron blocking materials of light-emitting devices D11 to D17 were all at least 0.5 eV higher than -2.99 eV, indicating that light-emitting devices D11 to D17 have a configuration that provides sufficient electron blocking performance.

[0614] Furthermore, the GSP_slope of the PCBBiF used in the first hole transport layer was 17.3 mV / nm, which is lower than that of the second hole transport layer (electron blocking layer) and lower than 20 mV / nm.

[0615] The above-mentioned light-emitting device was sealed on a glass substrate in a glove box under a nitrogen atmosphere to prevent exposure to the atmosphere (sealant was applied around the element, UV treatment was performed during sealing, and heat treatment was performed at 80°C for 1 hour). After this, the initial characteristics were measured. No special measures were taken to improve the extraction efficiency of the glass substrate on which the light-emitting device was fabricated.

[0616] Figure 26 shows the brightness-current density characteristics of each of the above light-emitting devices, Figure 27 shows the current efficiency-brightness characteristics, Figure 28 shows the brightness-voltage characteristics, Figure 29 shows the current density-voltage characteristics, Figure 30 shows the external quantum efficiency-brightness characteristics, Figure 31 shows the power efficiency-brightness characteristics, and Figure 32 shows the emission spectrum. Furthermore, the emission spectrum of each light-emitting device at 1000 cd / m² is shown. 2 Table 8 shows the main characteristics of the vicinity. A spectroradiometer (Topcon SR-UL1R) was used to measure luminance, CIE chromaticity, and emission spectrum at room temperature. The external quantum efficiency is a reference value calculated using the measured luminance and emission spectrum, assuming a Lambertsian type light distribution pattern.

[0617] [Table 8]

[0618] From Figures 26 to 32 and Table 8, it was found that light-emitting devices D11 to D17, which use transport materials with a GSP_slope of 20 or more in the electron block layer, are light-emitting devices with good characteristics, such as lower driving voltage and higher luminous efficiency, compared to light-emitting devices CD11 and CD12, which use transport materials with a GSP_slope of 20 or less. [Examples]

[0619] <<Synthesis Example 1>> This example describes a method for synthesizing an organic compound, N-2',4',6'-tricyclohexyl-1,1'-biphenyl-4-yl-N-(4-cyclohexylphenyl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviated as ch3BichPAF), which is one embodiment of the present invention. The structure of ch3BichPAF is shown below.

[0620] [ka]

[0621] <Step 1: Synthesis of 4'-chloro-2,4,6-tricyclohexyl-1,1'-biphenyl> 5.0 g (12 mmol) of 1-bromo-2,4,6-tricyclohexylbenzene, 2.0 g (13 mmol) of 4-chlorophenylboronic acid, 5.1 g (37 mmol) of potassium carbonate, 62 mL of toluene, 16 mL of ethanol, and 20 mL of tap water were placed in a three-necked flask. After degassing under reduced pressure, the flask was purged with nitrogen, and 0.30 mg (0.25 mmol) of tetrakis(triphenylphosphine)palladium(0) was added. This mixture was heated at 80°C for approximately 10 hours. After returning to room temperature, the organic layer and aqueous layer were separated. Magnesium sulfate was added to this solution, and the water was dried and concentrated. The resulting hexane solution was purified by silica gel column chromatography to obtain 3.2 g of the target white solid in 60% yield.

[0622] [ka]

[0623] <Step 2: Synthesis of ch3BichPAF> In a three-necked flask, 1.7 g (3.9 mmol) of 4'-chloro-2,4,6-tricyclohexyl-1,1'-biphenyl obtained in Step 1, 1.4 g (3.9 mmol) of N-(4-cyclohexylphenyl)-N-(9,9-dimethyl-9H-fluoren-2yl)amine, 1.1 g (12 mmol) of sodium tert butoxide, and 15 mL of toluene were placed. After degassing under reduced pressure, the flask was purged with nitrogen, and 45 mg (0.11 mmol) of bis(dibenzylideneacetone)palladium(0) and 47 mg (0.23 mmol) of tri-tert-butylphosphine were added. This mixture was heated at 80°C for approximately 2 hours. After that, the flask temperature was reduced to approximately 60°C, approximately 1 mL of water was added, and the precipitated solid was filtered off and washed with toluene. The filtrate was concentrated, and the resulting toluene solution was purified by silica gel column chromatography. The resulting solution was concentrated to obtain a concentrated toluene solution. Ethanol was added to this toluene solution and concentrated under reduced pressure to obtain an ethanol suspension. The precipitate was filtered at approximately 20°C, and the resulting solid was dried under reduced pressure at approximately 80°C to obtain 2.4 g of the target white solid in 80% yield.

[0624] [ka]

[0625] Furthermore, nuclear magnetic resonance spectroscopy of the white solid obtained in step 3 above ( 1 The results of the analysis by 1H-NMR are shown in Figure 33 and the numerical data below. From this, it was found that N-2',4',6'-tricyclohexyl-1,1'-biphenyl-4-yl-N-(4-cyclohexylphenyl)-9,9-dimethyl-9H-fluoren-2-amine was successfully synthesized.

[0626] 1 H-NMR.δ(CDCl3):7.63(d,1H,J=7.4Hz),7.58(d,1H,J=8.0Hz),7.38(d,1H,J=7.5Hz),7.30(d, 1H,J=1.6Hz),7.18(d,1H,J=1.8Hz),7.13-7.17(m,3H),7.08-7.12(m,5H),7.03(d,2H,J=8.0Hz ),7.00(s,2H),2.48-2.54(m,2H),2.31-2.36(m,2H),1.92-1.96(m,4H),1.85-1.87(m,4H),1. 66-1.74(m,13H),1.44-1.55(m,5H),1.35-1.41(m,12H),1.21-1.32(m,4H),1.07-1.18(m,4H).

[0627] Next, 2.4 g of the obtained white solid was purified by sublimation using the train sublimation method. Sublimation purification was performed by heating at 265°C under conditions of a pressure of 2.9 Pa and an argon flow rate of 10 mL / min. After sublimation purification, 2.1 g of a slightly yellowish-white solid was obtained with a recovery rate of 88%.

[0628] Next, the ultraviolet-visible absorption spectrum (hereinafter simply referred to as "absorption spectrum") and emission spectrum of a toluene solution of ch3BichPAF were measured. For the absorption spectrum, an ultraviolet-visible spectrophotometer (JASCO Corporation, V550 model) was used, with the toluene solution placed in a quartz cell and measured at room temperature. For the emission spectrum, a fluorophotometer (JASCO Corporation, FP-8600 model) was used, with the toluene solution placed in a quartz cell and measured at room temperature. The obtained absorption and emission spectrum measurements are shown in Figure 34. The horizontal axis represents wavelength, and the vertical axis represents absorbance and emission intensity. In Figure 34, two solid lines are shown; the thin solid line represents the absorption spectrum, and the thick solid line represents the emission spectrum. The absorbance values ​​shown in Figure 34 are the result of subtracting the absorption spectrum measured with toluene alone in a quartz cell from the absorption spectrum measured with the toluene solution in a quartz cell.

[0629] As shown in Figure 34, the organic compound, ch3BichPAF, had an emission peak at 388 nm.

[0630] Next, the glass transition temperature (hereinafter referred to as "Tg") of ch3BichPAF was measured. Tg was measured using a differential scanning calorimetry system (PYRIS1DSC, manufactured by PerkinElmer Japan Co., Ltd.) with the powder placed on an aluminum cell, and the Tg was found to be 124°C. [Examples]

[0631] ≪Synthesis Example 2≫ This example describes a method for synthesizing an organic compound, N-(3',5'-di-t-butylbiphenyl-4-yl)-N-(4-cyclohexyl-biphenyl-2-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviated as mmtBuBichoBiF), which is one embodiment of the present invention. The structure of mmtBuBichoBiF is shown below.

[0632] [ka]

[0633] <Step 1: Synthesis of 5-bromo-2-chlorobiphenyl> 15.0 g (50 mmol) of 5-bromo-2-chloroiodobenzene, 6.7 g (55 mmol) of phenylboronic acid, 20.7 g (150 mmol) of potassium carbonate, 125 mL of toluene, 32 mL of ethanol, and 50 mL of water were added to a three-necked flask. After degassing under reduced pressure, the flask was purged with nitrogen. 580 mg (0.50 mmol) of tetrakis(triphenylphosphine)palladium(0) was added to this mixture, and the mixture was stirred under a nitrogen stream at approximately 80°C for approximately 8 hours. After that, the flask was allowed to cool to room temperature, and the mixture was separated into an organic layer and an aqueous layer. The obtained organic layer was washed with water and separated again. 6 g of magnesium sulfate was added to this organic layer, filtered, and washed with toluene. The toluene solution was concentrated, and the resulting oily substance was purified by silica gel column chromatography. The resulting solution was concentrated and dried under reduced pressure to obtain 12.8 g of the target colorless oily substance in 95% yield. Furthermore, the synthesis scheme for 5-bromo-2-chlorobiphenyl in Step 1 is shown in the following formula.

[0634] [ka]

[0635] <Step 2: Synthesis of 2-chloro-5-cyclohexylbiphenyl> 5.4 g (20 mmol) of 5-bromo-2-chlorobiphenyl synthesized in step 1 of the synthesis example was placed in a three-necked flask, and the flask was evacuated and then purged with nitrogen. 100 mL of anhydrous THF was added to this flask and the mixture was heated and stirred at approximately 50°C under a nitrogen stream. 183 mg (0.20 mmol) of tris(dibenzylideneacetone)dipalladium and 167 mg (0.40 mmol) of 2-dicyclohexylphosphino-2'-4'-6'-triisopropylbiphenyl (trademark: Xphos) were added to this flask, and the flask was heated to approximately 65°C. 22 ...

Claims

1. A material for a hole transport layer of a light-emitting device, having a surface potential gradient GSP_slope of a deposited film of 20 (mV / nm) or more.

2. In claim 1, A material for a hole transport layer of a light emitting device, wherein the GSP_slope is 100 (mV / nm) or less.

3. In claim 1 or 2, A material for a hole transport layer of a light emitting device, wherein the material for a hole transport layer has an ordinary refractive index for light with a wavelength of 450 nm of 1.50 or more and 1.75 or less.

4. In claim 1 or 2, A material for a hole transport layer of a light emitting device, wherein the material for a hole transport layer has an ordinary refractive index for light with a wavelength of 633 nm of 1.45 or more and 1.70 or less.

5. A material for an electron transport layer of a light-emitting device, in which the potential gradient GSP_slope of the surface potential of the evaporated film is 20 (mV / nm) or more, and the ordinary refractive index for light with a wavelength of 450 nm is 1.50 or more and 1.75 or less.

6. A material for an electron transport layer of a light-emitting device, in which the potential gradient GSP_slope of the surface potential of the evaporated film is 20 (mV / nm) or more, and the ordinary refractive index for light with a wavelength of 633 nm is 1.45 or more and 1.70 or less.

7. An anode; A cathode; an EL layer located between the anode and the cathode; The EL layer includes a hole transport layer and a light emitting layer, the hole transport layer is located between the anode and the light emitting layer; The hole transport layer is not in contact with the anode, A light-emitting device, wherein the hole transport layer comprises the hole transport layer material of claim 1 .

8. An anode; A cathode; an EL layer located between the anode and the cathode; The EL layer includes a hole injection layer, a hole transport layer, and a light emitting layer, the hole injection layer and the hole transport layer are located between the anode and the light emitting layer; the hole transport layer is located between the hole injection layer and the light emitting layer, A light-emitting device, wherein the hole transport layer comprises the hole transport layer material of claim 1 .

9. An anode; A cathode; an EL layer located between the anode and the cathode; The EL layer includes an electron transport layer and a light emitting layer, the electron transport layer is located between the cathode and the light emitting layer; The electron transport layer is not in contact with the cathode, A light emitting device, wherein the electron transport layer comprises the electron transport material of claim 5 .

10. An anode; A cathode; an EL layer located between the anode and the cathode; The EL layer includes an electron injection layer, an electron transport layer, and a light emitting layer, the electron injection layer and the electron transport layer are located between the cathode and the light emitting layer; the electron transport layer is located between the electron injection layer and the light emitting layer; A light emitting device, wherein the electron transport layer comprises the electron transport material of claim 5 .

11. 11. An electronic device comprising: the light-emitting device according to claim 7; and a sensor, an operation button, a speaker, or a microphone.

Images