Light-emitting devices

Abstract

To provide light-emitting devices with high luminous efficiency. [Solution] A light-emitting device is provided having a first electrode, a second electrode, a light-emitting layer, a first hole transport layer, and a first electron transport layer, wherein the first electrode is formed on a substrate and located between the second electrode and the substrate, the light-emitting layer, the first hole transport layer, and the first electron transport layer are located between the first electrode and the second electrode, the light-emitting layer is located between the first hole transport layer and the first electron transport layer, the light-emitting layer and the first hole transport layer are in contact with each other, and the GSP_slope(mV / nm) of the layer located on the second electrode side of the light-emitting layer and the first hole transport layer is smaller than the GSP_slope(mV / nm) of the layer located on the first electrode side. However, GSP_slope(mV / nm) is expressed as ΔV / Δd when the change in surface potential ΔV(mV) is equal to the change in film thickness Δd(nm).

Description

[Technical Field]

[0001] One aspect of the present invention relates to organic compounds, organic semiconductor elements, light-emitting elements, organic EL elements, photodiodes, 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 field. The technical field of one aspect of the invention disclosed herein relates to a product, a method, or a method of manufacture. Alternatively, one aspect of the present invention relates to a process, a machine, a manufacture, or a composition of matter. More specifically, examples of the technical field 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 elements) that utilize electroluminescence (EL) using organic compounds is progressing. The basic structure of these organic EL elements 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 organic EL elements 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 organic EL elements is that they can be manufactured to be thin and lightweight. Furthermore, they are characterized by their extremely fast response speed.

[0004] Furthermore, because these organic EL elements can have their light-emitting layers formed continuously in a planar manner, 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 organic EL elements are suitable for various electronic devices, but research and development are underway to find organic EL elements 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 a light-emitting device with high luminous efficiency. Another aspect of the present invention aims to provide a light-emitting device with a low driving voltage. Yet another aspect of the present invention aims to provide a light-emitting device, electronic device, or display device with low power consumption.

[0008] Furthermore, the description of these problems does not preclude the existence of other problems. Moreover, one aspect of the present invention does not need to solve all of these problems. Other problems will naturally become apparent from the description in the specification, drawings, and claims, and it is possible to extract other problems from the description in the specification, drawings, and claims. [Means for solving the problem]

[0009] One aspect of the present invention is a light-emitting device that efficiently emits excitons generated in the light-emitting layer by selecting the organic compounds used in each layer of the organic compound layer of a forward-stacked light-emitting device such that, in the organic compound layer of the forward-stacked light-emitting device, the GSP_slope (mV / nm), which represents the magnitude of the giant surface potential (GSP) of the light-emitting layer, is smaller than the GSP_slope (mV / nm) of at least one of the carrier transport layers flanking the light-emitting layer, and in the organic compound layer of an inverted-stacked light-emitting device, the GSP_slope (mV / nm) of the light-emitting layer is larger than the GSP_slope (mV / nm) of at least one of the carrier transport layers flanking the light-emitting layer.

[0010] One aspect of the present invention is a light-emitting device comprising a first electrode, a second electrode, a light-emitting layer, a first hole transport layer, and a first electron transport layer, wherein the light-emitting layer, the first hole transport layer, and the first electron transport layer are located between the first electrode and the second electrode, the light-emitting layer is located between the first hole transport layer and the first electron transport layer, the light-emitting layer and the first hole transport layer are in contact with each other, and the GSP_slope(mV / nm) of the layer located on the second electrode side of the light-emitting layer and the first hole transport layer is smaller than the GSP_slope(mV / nm) of the layer located on the first electrode side. However, the first electrode is formed on a substrate and located between the second electrode and the substrate. Alternatively, the first electrode is electrically connected to a transistor. Alternatively, a portion of the first electrode is covered with an insulator. Alternatively, the first electrode is formed on an insulating film and located between the second electrode and the insulating film, and an external connection electrode is provided on the insulating film.

[0011] One aspect of the present invention is a light-emitting device comprising a first electrode, a second electrode, a light-emitting layer, a first hole transport layer, and a first electron transport layer, wherein the light-emitting layer, the first hole transport layer, and the first electron transport layer are located between the first electrode and the second electrode, the light-emitting layer is located between the first hole transport layer and the first electron transport layer, and the GSP_slope(mV / nm) of the layer located on the first electrode side of the light-emitting layer and the first electron transport layer is smaller than the GSP_slope(mV / nm) of the layer located on the second electrode side. However, the first electrode is formed on a substrate and located between the second electrode and the substrate. Alternatively, the first electrode is electrically connected to a transistor. Alternatively, a portion of the first electrode is covered with an insulator. Alternatively, the first electrode is formed on an insulating film and located between the second electrode and the insulating film, and an external connection electrode is provided on the insulating film.

[0012] One aspect of the present invention is a light-emitting device in which, in the above configuration, the GSP_slope(mV / nm) of the layer located on the second electrode side of the light-emitting layer and the first hole transport layer is smaller than the GSP_slope(mV / nm) of the layer located on the first electrode side.

[0013] One aspect of the present invention is a light-emitting device having the above configuration, wherein the second hole transport layer and the second electron transport layer are located between a first electrode and a second electrode, the first hole transport layer is located between the second hole transport layer and the light-emitting layer, the first electron transport layer is located between the second electron transport layer and the light-emitting layer, and of the first hole transport layer and the second hole transport layer, the GSP_slope(mV / nm) of the layer located on the second electrode side is greater than the GSP_slope(mV / nm) of the layer located on the first electrode side, and of the first electron transport layer and the second electron transport layer, the GSP_slope(mV / nm) of the layer located on the first electrode side is greater than the GSP_slope(mV / nm) of the layer located on the second electrode side.

[0014] One aspect of the present invention is a light-emitting device in which, in the above configuration, the difference between the GSP_slope (mV / nm) of the light-emitting layer and the GSP_slope (mV / nm) of the first hole transport layer is 0mV / nm or more and 20mV / nm or less.

[0015] One aspect of the present invention is a light-emitting device in which, in the above configuration, the difference between the GSP_slope (mV / nm) of the light-emitting layer and the GSP_slope (mV / nm) of the first electron transport layer is 0mV / nm or more and 20mV / nm or less.

[0016] One aspect of the present invention is a light-emitting device in which, in the above configuration, the difference between the GSP_slope(mV / nm) of the first hole transport layer and the GSP_slope(mV / nm) of the first electron transport layer is 0mV / nm or more and 20mV / nm or less.

[0017] One aspect of the present invention is a light-emitting device in which, in the above configuration, the refractive index of at least one of the first hole transport layer and the first electron transport layer is 1.75 or less at the peak wavelength of the electroluminescence spectrum of the light-emitting device.

[0018] One aspect of the present invention is a light-emitting device in which, in the above configuration, the refractive index of at least one of the second hole transport layer and the second electron transport layer is 1.75 or less at the peak wavelength of the electroluminescence spectrum of the light-emitting device.

[0019] One aspect of the present invention is a light-emitting device comprising a first electrode, a second electrode, a light-emitting layer, a first hole transport layer, and a first electron transport layer, wherein the light-emitting layer, the first hole transport layer, and the first electron transport layer are located between the first electrode and the second electrode, the first hole transport layer is located between the first electrode and the light-emitting layer, the first electron transport layer is located between the second electrode and the light-emitting layer, the light-emitting layer and the first hole transport layer are in contact with each other, the light-emitting layer comprises a host material and a light-emitting substance, the first hole transport layer comprises a first organic compound, and the first electron transport layer comprises a second organic compound, wherein the GSP_slope (mV / nm) of the vapor-deposited film of the host material is smaller than the GSP_slope (mV / nm) of the vapor-deposited film of the first organic compound. However, the first electrode is formed on a substrate and located between the second electrode and the substrate. Alternatively, the first electrode is electrically connected to a transistor. Alternatively, the first electrode may be partially covered with an insulator. Alternatively, the first electrode may be formed on an insulating film and located between the second electrode and the insulating film, with an external connection electrode provided on the insulating film.

[0020] One aspect of the present invention is a light-emitting device comprising a first electrode, a second electrode, a light-emitting layer, a first hole transport layer, and a first electron transport layer, wherein the light-emitting layer, the first hole transport layer, and the first electron transport layer are located between the first electrode and the second electrode, the first hole transport layer is located between the first electrode and the light-emitting layer, and the first electron transport layer is located between the second electrode and the light-emitting layer, the light-emitting layer comprises a host material and a light-emitting substance, the first hole transport layer comprises a first organic compound, and the first electron transport layer comprises a second organic compound, wherein the GSP_slope (mV / nm) of the vapor-deposited film of the host material is smaller than the GSP_slope (mV / nm) of the vapor-deposited film of the second organic compound. However, the first electrode is formed on a substrate and located between the second electrode and the substrate. Alternatively, the first electrode is electrically connected to a transistor. Alternatively, a portion of the first electrode is covered with an insulator. Alternatively, the first electrode is formed on an insulating film and is located between the second electrode and the insulating film, and an external connection electrode is provided on the insulating film.

[0021] Furthermore, one aspect of the present invention is a light-emitting device in which, in the above configuration, the GSP_slope (mV / nm) of the vapor-deposited film of the host material is smaller than the GSP_slope (mV / nm) of the vapor-deposited film of the first organic compound.

[0022] One aspect of the present invention is a light-emitting device having the above configuration, wherein the device has a second hole transport layer and a second electron transport layer, the second hole transport layer and the second electron transport layer are located between a first electrode and a second electrode, the first hole transport layer is located between the second hole transport layer and a light-emitting layer, the first electron transport layer is located between the second electron transport layer and a light-emitting layer, the second hole transport layer has a third organic compound, the second electron transport layer has a fourth organic compound, the GSP_slope(mV / nm) of the vapor-deposited film of the first organic compound is greater than the GSP_slope(mV / nm) of the vapor-deposited film of the third organic compound, and the GSP_slope(mV / nm) of the vapor-deposited film of the second organic compound is greater than the GSP_slope(mV / nm) of the vapor-deposited film of the fourth organic compound.

[0023] One aspect of the present invention is a light-emitting device in which, in the above configuration, the difference between the GSP_slope (mV / nm) of the vapor-deposited film of the host material and the GSP_slope (mV / nm) of the vapor-deposited film of the first organic compound is 0 mV / nm or more and 20 mV / nm or less.

[0024] One aspect of the present invention is a light-emitting device in which, in the above configuration, the difference between the GSP_slope (mV / nm) of the vapor-deposited film of the host material and the GSP_slope (mV / nm) of the vapor-deposited film of the second organic compound is 0 mV / nm or more and 20 mV / nm or less.

[0025] One aspect of the present invention is a light-emitting device in which, in the above configuration, the difference between the GSP_slope (mV / nm) of the vapor-deposited film of the first organic compound and the GSP_slope (mV / nm) of the vapor-deposited film of the second organic compound is 0 mV / nm or more and 20 mV / nm or less.

[0026] One aspect of the present invention is a light-emitting device in which, in the above configuration, at the peak wavelength of the electroluminescence spectrum of the light-emitting device, at least one of the refractive index of the first organic compound film and the refractive index of the second organic compound film is 1.75 or less.

[0027] One aspect of the present invention is a light-emitting device in which, in the above configuration, at least one of the first organic compound and the second organic compound is an organic compound having at least one group selected from a chain alkyl group having 2 to 10 carbon atoms and a cycloalkyl group having 6 to 12 carbon atoms.

[0028] One aspect of the present invention is a light-emitting device in which, in the above configuration, the refractive index of the film of the third organic compound is 1.75 or less at the peak wavelength of the electroluminescence spectrum of the light-emitting device.

[0029] One aspect of the present invention is a light-emitting device in which, in the above configuration, at least one of the third organic compound and the fourth organic compound is an organic compound having at least one group selected from a chain alkyl group having 2 to 10 carbon atoms and a cycloalkyl group having 6 to 12 carbon atoms.

[0030] One aspect of the present invention is a light-emitting device in which the light-emitting material is a fluorescent light-emitting material.

[0031] One aspect of the present invention is a light-emitting device in which, in the above configuration, the energy difference between the HOMO level of the host material and the HOMO level of the light-emitting material is 0.25 eV or more, and the concentration of the light-emitting material in the light-emitting layer is 0.5 wt% or more and 25 wt% or less relative to the host material.

[0032] However, in one embodiment of the present invention, GSP_slope(mV / nm) is expressed as ΔV / Δd when the change in surface potential ΔV(mV) is equal to the change in film thickness Δd(nm). [Effects of the Invention]

[0033] According to one aspect of the present invention, a light-emitting device with high luminous efficiency can be provided. According to one aspect of the present invention, a light-emitting device with a low driving voltage can be provided. Furthermore, according to one aspect of the present invention, a light-emitting device, electronic device, or display device with low power consumption can be provided.

[0034] 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]

[0035] [Figure 1] Figures 1(A) and 1(B) illustrate the configuration of a light-emitting device according to an embodiment. [Figure 2] Figures 2(A) and 2(B) illustrate the configuration of a light-emitting device according to an embodiment. [Figure 3] Figures 3(A) and 3(B) illustrate the configuration of a light-emitting device according to an embodiment. [Figure 4] Figures 4(A) and 4(B) illustrate the configuration of a light-emitting device according to an embodiment. [Figure 5] Figures 5(A) to 5(D) illustrate the configuration of a light-emitting device according to an embodiment. [Figure 6] Figures 6(A) to 6(E) illustrate the configuration of a light-emitting device according to an embodiment. [Figure 7] Figures 7(A) and 7(B) are a top view and a cross-sectional view of the light-emitting device. [Figure 8] Figures 8(A) to 8(G) are top views showing examples of pixel configurations. [Figure 9] Figures 9(A) to 9(I) are top views showing examples of pixel configurations. [Figure 10]Figures 10(A) and 10(B) are perspective views showing examples of the display module configuration. [Figure 11] Figures 11(A) and 11(B) are cross-sectional views showing examples of the configuration of a light-emitting device. [Figure 12] Figure 12 is a perspective view showing an example of the configuration of a light-emitting device. [Figure 13] Figure 13(A) is a cross-sectional view showing an example of the configuration of a light-emitting device. Figures 13(B) and 13(C) are cross-sectional views showing an example of the configuration of a transistor. [Figure 14] Figure 14 is a cross-sectional view showing an example of the configuration of a light-emitting device. [Figure 15] Figures 15(A) to 15(C) are cross-sectional and top views showing examples of the configuration of a light-emitting device. [Figure 16] Figures 16(A) to 16(D) are cross-sectional views showing examples of the configuration of a light-emitting device. [Figure 17] Figures 17(A) to 17(C) are cross-sectional and top views showing examples of the configuration of a light-emitting device. [Figure 18] Figures 18(A) to 18(D) show examples of electronic devices. [Figure 19] Figures 19(A) through 19(F) show examples of electronic devices. [Figure 20] Figures 20(A) through 20(G) show examples of electronic devices. [Figure 21] Figures 21(A) and 21(B) are diagrams representing an active matrix type light-emitting device. [Figure 22] Figures 22(A) and 22(B) are diagrams representing an active matrix type light-emitting device. [Figure 23] Figure 23 is a diagram representing an active matrix type light-emitting device. [Figure 24] Figures 24(A) and 24(B) are diagrams representing passive matrix type light-emitting devices. [Figure 25] Figures 25(A) and 25(B) illustrate the electronic device according to the embodiment. [Figure 26]Figure 26 is a diagram illustrating an electronic device according to an embodiment. [Figure 27] Figure 27 is a diagram illustrating the configuration of a device according to an embodiment. [Figure 28] Figure 28 shows the capacitance-voltage characteristics of the measuring device 1. [Figure 29] Figure 29 shows the current density-voltage characteristics of the measuring device 1. [Figure 30] Figure 30 shows the luminance-current density characteristics of light-emitting device 1, light-emitting device 2, and comparative light-emitting devices 4 to 6. [Figure 31] Figure 31 shows the luminance-voltage characteristics of light-emitting device 1, light-emitting device 2, and comparative light-emitting devices 4 to 6. [Figure 32] Figure 32 shows the current efficiency-luminance characteristics of light-emitting device 1, light-emitting device 2, and comparative light-emitting devices 4 to 6. [Figure 33] Figure 33 shows the current density-voltage characteristics of light-emitting device 1, light-emitting device 2, and comparative light-emitting devices 4 to 6. [Figure 34] Figure 34 shows the power efficiency-luminance characteristics of light-emitting device 1, light-emitting device 2, and comparative light-emitting devices 4 through 6. [Figure 35] Figure 35 shows the external quantum efficiency-luminance characteristics of light-emitting device 1, light-emitting device 2, and comparative light-emitting devices 4 to 6. [Figure 36] Figure 36 shows the blue index-luminance characteristics of light-emitting device 1, light-emitting device 2, and comparative light-emitting devices 4 to 6. [Figure 37] Figure 37 shows the electroluminescence spectra of light-emitting device 1, light-emitting device 2, and comparative light-emitting devices 4 to 6. [Figure 38] Figure 38 shows the luminance-current density characteristics of light-emitting device 3 and comparative light-emitting devices 7 to 9. [Figure 39]Figure 39 shows the luminance-voltage characteristics of light-emitting device 3 and comparative light-emitting devices 7 to 9. [Figure 40] Figure 40 shows the current efficiency-luminance characteristics of light-emitting device 3 and comparative light-emitting devices 7 to 9. [Figure 41] Figure 41 shows the current density-voltage characteristics of light-emitting device 3 and comparative light-emitting devices 7 to 9. [Figure 42] Figure 42 shows the power efficiency-luminance characteristics of light-emitting device 3 and comparative light-emitting devices 7 to 9. [Figure 43] Figure 43 shows the external quantum efficiency-luminance characteristics of light-emitting device 3 and comparative light-emitting devices 7 to 9. [Figure 44] Figure 44 shows the blue index-luminance characteristics of light-emitting device 3 and comparative light-emitting devices 7 to 9. [Figure 45] Figure 45 shows the electroluminescence spectra of light-emitting device 3 and comparative light-emitting devices 7 to 9. [Figure 46] Figures 46(A) and 46(B) show the emission spectra of 3,10PCA2Nbf(IV)-02. [Figure 47] Figure 47 shows the emission spectrum of Bnf(II)PhA-02-d5. [Figure 48] Figures 48(A) and 48(B) show the emission spectra of Bnf(II)PhA-02-d5 (with triplet sensitizer added). [Figure 49] Figure 49 shows the fluorescence lifetimes of light-emitting device 1, light-emitting device 2, light-emitting device 3, and comparative light-emitting device 5. [Figure 50] Figure 50 shows the luminance-current density characteristics of light-emitting devices 10 to 13, reference light-emitting device 14, and reference light-emitting device 15. [Figure 51]Figure 51 shows the luminance-voltage characteristics of light-emitting devices 10 to 13, reference light-emitting device 14, and reference light-emitting device 15. [Figure 52] Figure 52 shows the current efficiency-luminance characteristics of light-emitting devices 10 to 13, comparative light-emitting device 14, and comparative light-emitting device 15. [Figure 53] Figure 53 shows the current density-voltage characteristics of light-emitting devices 10 to 13, reference light-emitting device 14, and reference light-emitting device 15. [Figure 54] Figure 54 shows the power efficiency-luminance characteristics of light-emitting devices 10 to 13, comparative light-emitting device 14, and comparative light-emitting device 15. [Figure 55] Figure 55 shows the external quantum efficiency-luminance characteristics of light-emitting devices 10 to 13, comparative light-emitting device 14, and comparative light-emitting device 15. [Figure 56] Figure 56 shows the blue index-luminance characteristics of light-emitting devices 10 to 13, reference light-emitting device 14, and reference light-emitting device 15. [Figure 57] Figure 57 shows the electroluminescence spectra of light-emitting devices 10 to 13, reference light-emitting device 14, and reference light-emitting device 15. [Figure 58] Figure 58 shows the emission spectrum of 2αN-αNPhA. [Figure 59] Figures 59(A) and 59(B) show the emission spectra of 2αN-αNPhA (with triplet sensitizer added). [Figure 60] Figure 60 shows the fluorescence lifetimes of the light-emitting device 10 and the comparative light-emitting device 15. [Modes for carrying out the invention]

[0036] The embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention is not limited to the following description, and 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.

[0037] Please note that the positions, sizes, and ranges of each component shown in the drawings may not represent their actual positions, sizes, and ranges for the sake of ease of understanding. Therefore, the disclosed invention is not necessarily limited to the positions, sizes, and ranges disclosed in the drawings.

[0038] In this specification, the ordinal numbers "first," "second," etc., are used for convenience only and do not limit the number of components or the order of components. The order of components includes, for example, the order of processes or the order of stacking. That is, the ordinal numbers used in the embodiments of this specification may not match the ordinal numbers used in the claims. Also, the ordinal numbers used in the examples of this specification may not match the ordinal numbers used in the claims. Also, the ordinal numbers used in the embodiments of this specification may not match the ordinal numbers used in the examples of this specification.

[0039] Furthermore, in this specification and other documents, when describing the structure of the invention using drawings, reference numerals that refer to the same thing may be used in common across different drawings.

[0040] Furthermore, in this specification, the terms "film" and "layer" are interchangeable. For example, the term "conductive layer" may be changed to "conductive film." Or, for example, the term "insulating film" may be changed to "insulating layer."

[0041] In this specification, a photoluminescence (PL) spectrum refers to a spectrum obtained by fixing the excitation wavelength of the excitation light and scanning the wavelength of emission in fluorescence photometry. It may also be called an emission spectrum. An emission spectrum may contain both a fluorescent component and a phosphorescent component. In this specification, an emission spectrum consisting of a fluorescent component may be specifically called a fluorescence spectrum, and an emission spectrum consisting of a phosphorescent component may be specifically called a phosphorescent spectrum.

[0042] (Embodiment 1) In this embodiment, a light-emitting device 10A, which is a light-emitting device according to one aspect of the present invention, and a light-emitting device 10B, which is a light-emitting device according to another aspect of the present invention, will be described with reference to Figures 1(A) to 5(D).

[0043] As shown in Figures 1(A) to 4(B), the light-emitting devices 10A and 10B are each located on the substrate 1000. The light-emitting devices 10A and 10B each have a first electrode 101, a second electrode 102, and an organic compound layer 103 located between the first electrode 101 and the second electrode 102. Also, as shown in Figures 1(A) to 4(B), the organic compound layer 103 has at least a light-emitting layer 113, a hole transport layer 112, and an electron transport layer 114. The hole transport layer 112 has the function of transporting holes injected into the organic compound layer 103 from either the first electrode 101 or the second electrode 102 to the light-emitting layer 113. The electron transport layer 114 has the function of transporting electrons injected into the organic compound layer 103 from either the first electrode 101 or the second electrode 102 to the light-emitting layer 113.

[0044] Furthermore, as shown in Figures 1(A) to 4(B), in the light-emitting devices 10A and 10B, the first electrode 101 is formed on the substrate 1000. It can also be said that the first electrode 101 is provided between the second electrode 102 and the substrate 1000. That is, the first electrode 101 is an electrode provided before the second electrode 102. When a transistor is provided on the substrate 1000, the first electrode 101 is electrically connected to the transistor via wiring. Alternatively, the first electrode 101 is provided on an insulating layer on which external connection electrodes are provided, such as terminals for attaching FPCs (flexible printed circuits). Furthermore, on the substrate 1000 or insulating layer on which the first electrode 101 is provided, a portion of the first electrode 101 may be covered with an insulator.

[0045] The light-emitting devices 10A shown in Figures 1(A), 2(A), 3(A), and 4(A) and 10B shown in Figures 1(B), 2(B), 3(B), and 4(B) differ in the functions of the first electrode 101 and the second electrode 102. In light-emitting device 10A, the first electrode 101 functions as the anode, and the second electrode 102 functions as the cathode. In this specification, a light-emitting device like light-emitting device 10A, in which the first electrode provided on the substrate side functions as the anode, is sometimes referred to as a forward-stacked light-emitting device. On the other hand, in light-emitting device 10B, the first electrode 101 functions as the cathode, and the second electrode 102 functions as the anode. In this specification, a light-emitting device like light-emitting device 10B, in which the first electrode provided on the substrate side functions as the cathode, is sometimes referred to as a reverse-stacked light-emitting device.

[0046] In the sequentially stacked light-emitting device 10A, holes are injected into the organic compound layer 103 from the first electrode 101, which functions as the anode, and transported by the hole transport layer 112. These holes, along with electrons injected into the organic compound layer 103 from the second electrode 102, which functions as the cathode, and transported by the electron transport layer 114, recombine in the light-emitting layer 113 to produce light. Therefore, in the light-emitting device 10A, the hole transport layer 112 is preferably located between the first electrode 101 and the light-emitting layer 113, and the electron transport layer 114 is preferably located between the second electrode 102 and the light-emitting layer 113.

[0047] In the inverted stacking type light-emitting device 10B, electrons are injected from the first electrode 101, which functions as a cathode, into the organic compound layer 103 and transported by the electron transport layer 114, and holes are injected from the second electrode 102, which functions as an anode, into the organic compound layer 103 and transported by the hole transport layer 112, and these recombine in the light-emitting layer 113 to emit light. Therefore, in the light-emitting device 10B, it is preferable that the hole transport layer 112 is located between the second electrode 102 and the light-emitting layer 113, and that the electron transport layer 114 is located between the first electrode 101 and the light-emitting layer 113.

[0048] In the light-emitting devices 10A and 10B, the hole transport layer 112 and the electron transport layer 114 may each be a single layer or a configuration in which multiple layers are stacked (hereinafter also referred to as a stacked structure). The organic compound layer 103 of the light-emitting device 10A shown in Figure 4(A) and the light-emitting device 10B shown in Figure 4(B) has at least a light-emitting layer 113, a first hole transport layer 112_1, a second hole transport layer 112_2, a first electron transport layer 114_1, and a second electron transport layer 114_2. In the organic compound layer 103 of the light-emitting device 10A shown in Figure 4(A), the first hole transport layer 112_1 is located between the first electrode 101 and the light-emitting layer 113, the second hole transport layer 112_2 is located between the first hole transport layer 112_1 and the first electrode 101, the first electron transport layer 114_1 is located between the second electrode 102 and the light-emitting layer 113, and the second electron transport layer 114_2 is located between the first electron transport layer 114_1 and the second electrode 102. Furthermore, in the organic compound layer 103 of the light-emitting device 10B shown in Figure 4(B), the first electron transport layer 114_1 is located between the first electrode 101 and the light-emitting layer 113, the second electron transport layer 114_2 is located between the first electron transport layer 114_1 and the first electrode 101, the first hole transport layer 112_1 is located between the second electrode 102 and the light-emitting layer 113, and the second hole transport layer 112_2 is located between the first hole transport layer 112_1 and the second electrode 102. Hereinafter, the first hole transport layer 112_1 and the second hole transport layer 112_2 may be collectively referred to as the hole transport layer 112, and the first electron transport layer 114_1 and the second electron transport layer 114_2 may be collectively referred to as the electron transport layer 114.

[0049] Furthermore, it is more preferable that the light-emitting devices 10A and 10B have a hole injection layer 111 between the anode and the hole transport layer 112, and an electron injection layer 115 between the cathode and the electron transport layer 114. The sequentially stacked light-emitting device 10A shown in Figures 1(A), 2(A), and 3(A) has a structure in which a hole injection layer 111, a hole transport layer 112, a light-emitting layer 113, an electron transport layer 114, an electron injection layer 115, and a second electrode 102 that functions as a cathode are sequentially stacked on a first electrode 101 that functions as an anode. Furthermore, the forward-stacked light-emitting device 10A shown in Figure 4(A) has a structure in which a hole injection layer 111, a second hole transport layer 112_2, a first hole transport layer 112_1, a light-emitting layer 113, a first electron transport layer 114_1, a second electron transport layer 114_2, an electron injection layer 115, and a second electrode 102 that functions as a cathode are sequentially stacked on a first electrode 101 that functions as an anode. Furthermore, the inverted-stacked light-emitting device 10B shown in Figures 1(B), 2(B), and 3(B) has a structure in which an electron injection layer 115, an electron transport layer 114, a light-emitting layer 113, a hole transport layer 112, a hole injection layer 111, and a second electrode 102 that functions as an anode are sequentially stacked on a first electrode 101 that functions as a cathode. Furthermore, the inverted stacking type light-emitting device 10B shown in Figure 4(B) has a structure in which an electron injection layer 115, a second electron transport layer 114_2, a first electron transport layer 114_1, a light-emitting layer 113, a first hole transport layer 112_1, a second hole transport layer 112_2, a hole injection layer 111, and a second electrode 102 that functions as an anode are sequentially stacked on a first electrode 101 that functions as a cathode.

[0050] The configurations of the light-emitting devices 10A and 10B are not limited to those shown in Figures 1(A) to 4(B). For example, they may have one hole transport layer and one electron transport layer, and two electron transport layers. Alternatively, they may have three or more hole transport layers and one or both electron transport layers. Furthermore, they may have a functional layer that has functions such as reducing the injection barrier for holes or electrons, improving the transportability of holes or electrons, inhibiting the transportability of holes or electrons, or suppressing quenching by electrodes.

[0051] The present inventors have found that the luminescence efficiency of light-emitting devices 10A and 10B can be increased by selecting materials for each layer, taking into account the GSP_slope of the light-emitting layer 113 and the layers surrounding the light-emitting layer 113.

[0052] GSP is a phenomenon caused by spontaneous orientation polarization (SOP), which occurs when the orientation of the permanent electric dipole moment of a deposited film is biased in the direction of film thickness.

[0053] The surface potential of a vapor-deposited film exhibiting GSP changes at a constant rate without saturating as the film thickness increases. For example, a vapor-deposited film of tris(8-quinolinolato)aluminum (abbreviated as Alq3) has a surface potential of approximately 28V at a film thickness of 560nm. This electric field strength is 5 × 10⁻¹⁰ 5 It reaches V / cm, which is about the same magnitude as the electric field strength during operation of a typical light-emitting device.

[0054] GSP_slope is expressed as ΔV / Δd when the change in surface potential (GSP) is proportional to the film thickness, and the change in surface potential (GSP) is ΔV (mV) for a change in film thickness (Δd (nm)). Note that if the surface potential increases with increasing film thickness, the GSP_slope is positive; if the surface potential decreases with increasing film thickness, the GSP_slope is negative. Alq3 can be described as a material with a positive GSP_slope. In layers with a positive GSP_slope, the substrate side has a low potential, while in layers with a negative GSP_slope, the substrate side has a high potential.

[0055] As mentioned above, this GSP is a phenomenon caused by SOP resulting from the bias in the orientation of the permanent electric dipole moment in the film thickness direction. In other words, in layers where GSP_slope is positive, it can be considered that a negative polarization charge is induced on the deposition start side (substrate side) and a positive polarization charge is induced on the deposition end side (second electrode side). Similarly, in layers where GSP_slope is negative, it can be considered that a positive polarization charge is induced on the deposition start side (substrate side) and a negative polarization charge is induced on the deposition end side (second electrode side). The induction of such polarization charges is the origin of GSP.

[0056] Since vapor-deposited films of organic compounds often have a positive GSP_slope, for example, when a second layer is deposited in contact with a first layer, the signs of the GSP_slope of the first and second layers will be the same positive, and it can be considered that a negative polarization charge is induced on the deposition start side of each layer, and a positive polarization charge is induced on the deposition end side. In this case, the negative polarization charge on the first layer side of the second layer cancels out with the positive polarization charge on the second layer side of the first layer, and only the remaining charge can be considered as the interfacial charge (fixed charge) at the interface between the first and second layers. Note that in this specification, a hypothetical charge that can be considered as an interfacial charge is sometimes referred to as an interfacial charge.

[0057] This virtual interfacial charge can sometimes reduce the luminescence efficiency of a light-emitting device. For example, if an excess negative interfacial charge can be assumed to remain at the interface between the hole transport layer 112 and the light-emitting layer 113 in a light-emitting device, holes may be excessively attracted to this interface from the anode side, causing exciton annihilation due to exciton-polaron interaction, which can reduce the luminescence efficiency of the light-emitting device.

[0058] Such a decrease in luminescence efficiency is particularly noticeable in light-emitting devices in which a fluorescent material that traps holes is added to the host material in the light-emitting layer 113 of the light-emitting device, and triplet-triplet annihilation (TTA) by multiple triplet excitons is utilized to increase luminescence efficiency. This is because, in light-emitting devices with such a configuration, the excitons are particularly localized on the hole transport layer 112 side of the light-emitting layer 113, making it easy for exciton annihilation due to exciton-polaron interaction to occur between the excitons and holes that are excessively attracted from the anode side to the interface between the hole transport layer 112 and the light-emitting layer 113.

[0059] In one aspect of the present invention, by controlling the polarization charge and the interfacial charge that can be considered to be generated in the multilayer film due to the polarization charge, the efficiency reduction of the light-emitting device caused by the interfacial charge is suppressed, and the efficiency of the light-emitting device is increased. In Figures 1(A) to 4(B), the spontaneous polarization that occurs when the orientation of the permanent electric dipole moment of each layer deposited by vapor deposition is biased in the film thickness direction is σ + and σ - This is shown using σ. + σ shows positive polarization, - It exhibits negative polarization. Also, the σ near the interface in each layer + or σ - A higher number of layers indicates greater spontaneous polarization.

[0060] For example, in a light-emitting device according to one aspect of the present invention, it is preferable that the GSP_slope of the layer located on the second electrode 102 side of the light-emitting layer 113 and hole transport layer 112 is smaller than the GSP_slope of the layer located on the first electrode 101 side (Configuration Example 1). Figure 1(A) shows a forward-stacked light-emitting device 10A to which Configuration Example 1 is applied, and Figure 1(B) shows an inverted-stacked light-emitting device 10B to which Configuration Example 1 is applied.

[0061] In the sequentially stacked light-emitting device 10A shown in Figure 1(A), the layer located on the second electrode 102 side of the light-emitting layer 113 and the hole transport layer 112 refers to the light-emitting layer 113, and the layer located on the first electrode 101 side of the light-emitting layer 113 and the hole transport layer 112 refers to the hole transport layer 112. That is, when configuration example 1 is applied to the sequentially stacked light-emitting device 10A, it is preferable that the GSP_slope of the light-emitting layer 113 is smaller than the GSP_slope of the hole transport layer 112.

[0062] In the inverted stacking type light-emitting device 10B shown in Figure 1(B), the layer located on the second electrode 102 side of the light-emitting layer 113 and the hole transport layer 112 is the hole transport layer 112, and the layer located on the first electrode 101 side of the light-emitting layer 113 and the hole transport layer 112 is the light-emitting layer 113. That is, when configuration example 1 is applied to the inverted stacking type light-emitting device 10B, it is preferable that the GSP_slope of the hole transport layer 112 is smaller than the GSP_slope of the light-emitting layer 113.

[0063] By applying Configuration Example 1 to the forward-stacked light-emitting device 10A and the inverted-stacked light-emitting device 10B, as shown in Figures 1(A) and 1(B), the polarization charge on the light-emitting layer 113 side of the hole transport layer 112 cancels out with the polarization charge on the hole transport layer 112 side of the light-emitting layer 113, and a positive interface charge 50a can be considered to remain at the interface between the hole transport layer 112 and the light-emitting layer 113. Therefore, hole injection from the anode side into the hole transport layer 112 is suppressed, and the accumulation of holes at the interface is prevented. As a result, the occurrence of exciton annihilation caused by exciton-polaron interaction can also be prevented, thereby increasing the luminescence efficiency of the light-emitting device. In particular, when applying Configuration Example 1 to a light-emitting device in which a fluorescent material is used in the light-emitting layer 113 and TTA is used to increase luminescence efficiency, the effect of increasing luminescence efficiency is high and preferable.

[0064] In configuration example 1, if the difference between the GSP_slope of the light-emitting layer 113 and the GSP_slope of the hole transport layer 112 is too large, the positive interfacial charge 50a that can be considered to remain at the interface between the hole transport layer 112 and the light-emitting layer 113 will become too large. This will cause electrons to be attracted to and accumulate at the interface, which may hinder carrier recombination in the light-emitting layer 113 and reduce the luminescence efficiency. Therefore, it is preferable that the difference between the GSP_slope of the light-emitting layer 113 and the GSP_slope of the hole transport layer 112 be between 0mV / nm and 20mV / nm. This relationship between the magnitudes of the GSP_slopes can further increase the luminescence efficiency of the light-emitting device.

[0065] Furthermore, in the case of Configuration Example 1, as described above, it is important to control the interfacial charge that can be considered to occur at the interface between the light-emitting layer 113 and the layer in contact with the light-emitting layer 113, so it is more preferable that the hole transport layer 112 is in contact with the light-emitting layer 113. Also, if the hole transport layer 112 has a stacked structure, it is preferable to design the light-emitting device so that the relationship between the GSP_slope of the hole transport layer 112 in contact with the light-emitting layer 113 and the GSP_slope of the light-emitting layer 113 is satisfied in Configuration Example 1. This makes it possible to further increase the luminous efficiency of the light-emitting device.

[0066] Furthermore, in a light-emitting device according to one aspect of the present invention, it is preferable that the GSP_slope of the layer located on the first electrode 101 side of the light-emitting layer 113 and electron transport layer 114 is smaller than the GSP_slope of the layer located on the second electrode 102 side (Configuration Example 2). Figure 2(A) shows a forward-stacked light-emitting device 10A to which Configuration Example 2 is applied, and Figure 2(B) shows a reverse-stacked light-emitting device 10B to which Configuration Example 2 is applied.

[0067] In the sequentially stacked light-emitting device 10A shown in Figure 2(A), the layer located on the first electrode 101 side of the light-emitting layer 113 and the electron transport layer 114 refers to the light-emitting layer 113, and the layer located on the second electrode 102 side of the light-emitting layer 113 and the electron transport layer 114 refers to the electron transport layer 114. That is, when configuration example 2 is applied to the sequentially stacked light-emitting device 10A, it is preferable that the GSP_slope of the light-emitting layer 113 is smaller than the GSP_slope of the electron transport layer 114.

[0068] In the inverted stacking type light-emitting device 10B shown in Figure 2(B), the layer located on the first electrode 101 side of the light-emitting layer 113 and electron transport layer 114 is the electron transport layer 114, and the layer located on the second electrode 102 side of the light-emitting layer 113 and electron transport layer 114 is the light-emitting layer 113. That is, when applying Configuration Example 2 to the inverted stacking type light-emitting device 10B, it is preferable that the GSP_slope of the electron transport layer 114 is smaller than the GSP_slope of the light-emitting layer 113.

[0069] By applying Configuration Example 2 to the forward-stacked light-emitting device 10A and the inverted-stacked light-emitting device 10B, as shown in Figures 2(A) and 2(B), the polarization charge on the electron transport layer 114 side of the light-emitting layer 113 cancels out with the polarization charge on the light-emitting layer 113 side of the electron transport layer 114, and a negative interfacial charge 50b can be considered to remain at the interface between the light-emitting layer 113 and the electron transport layer 114. As a result, holes are attracted to the interface from the anode side, which mitigates the localization of excitons in the light-emitting layer 113 toward the hole transport layer 112. Therefore, as shown in Figures 2(A) and 2(B), even if the GSP_slope of the layer located toward the second electrode 102 is greater than the GSP_slope of the layer located toward the first electrode 101, exciton annihilation caused by exciton-polaron interaction at the interface between the light-emitting layer 113 and the hole transport layer 112 can be suppressed, thereby increasing the luminescence efficiency of the light-emitting device. In particular, when applying Configuration Example 2 to a light-emitting device that uses a fluorescent material in the light-emitting layer 113 and utilizes TTA to increase luminescence efficiency, the effect of increasing luminescence efficiency is high and therefore preferable.

[0070] In configuration example 2, if the difference between the GSP_slope of the light-emitting layer 113 and the GSP_slope of the electron transport layer 114 is too large, the negative interfacial charge 50b that can be considered to remain at the interface between the light-emitting layer 113 and the electron transport layer 114 will become large, and holes will be attracted to and accumulate at this interface, which may inhibit carrier recombination in the light-emitting layer 113 and reduce the luminescence efficiency. Therefore, it is preferable that the difference between the GSP_slope of the light-emitting layer 113 and the GSP_slope of the electron transport layer 114 be between 0mV / nm and 20mV / nm. By having such a relative size of GSP_slope, the luminescence efficiency of the light-emitting device can be further increased.

[0071] Furthermore, in a light-emitting device according to one aspect of the present invention, it is preferable that the GSP_slope of the layer located on the second electrode 102 side of the light-emitting layer 113 and hole transport layer 112 is smaller than the GSP_slope of the layer located on the first electrode 101 side, and that the GSP_slope of the layer located on the first electrode 101 side of the light-emitting layer 113 and electron transport layer 114 is smaller than the GSP_slope of the layer located on the second electrode 102 side (Configuration Example 3). Figure 3(A) shows a forward-stacked light-emitting device 10A to which Configuration Example 3 is applied, and Figure 3(B) shows a reverse-stacked light-emitting device 10B to which Configuration Example 3 is applied.

[0072] In other words, when configuration example 3 is applied to a sequentially stacked light-emitting device 10A, it is preferable that the GSP_slope of the light-emitting layer 113 is smaller than the GSP_slope of the hole transport layer 112 and the GSP_slope of the electron transport layer 114.

[0073] Furthermore, when applying Configuration Example 3 to the inverted stacking type light-emitting device 10B, it is preferable that the GSP_slope of the light-emitting layer 113 is larger than the GSP_slope of the hole transport layer 112 and the GSP_slope of the electron transport layer 114.

[0074] As a result, as shown in Figures 3(A) and 3(B), a positive interfacial charge 50a can be considered to remain at the interface between the hole transport layer 112 and the light-emitting layer 113. Therefore, hole injection from the anode side into the hole transport layer 112 is suppressed, and hole accumulation at the interface is prevented. As a result, exciton annihilation caused by exciton-polaron interaction at the interface can be suppressed. Furthermore, a negative interfacial charge 50b can be considered to remain at the interface between the light-emitting layer 113 and the electron transport layer 114. This inhibits electron injection from the cathode side into the electron transport layer 114, making it easier to balance the hole injection from the anode side into the light-emitting layer 113 and the electron injection from the cathode side into the light-emitting layer 113. Therefore, the luminous efficiency of the light-emitting device can be increased. In particular, when applying Configuration Example 3 to a light-emitting device in which a fluorescent material is used in the light-emitting layer 113 and TTA is used to increase luminous efficiency, the effect of increasing luminous efficiency is high and preferable.

[0075] In configuration example 3, it is preferable that the difference between the GSP_slope of the light-emitting layer 113 and the GSP_slope of the hole transport layer 112 is between 0mV / nm and 20mV / nm, the difference between the GSP_slope of the light-emitting layer 113 and the GSP_slope of the electron transport layer 114 is between 0mV / nm and 20mV / nm, and the difference between the GSP_slope of the hole transport layer 112 and the GSP_slope of the electron transport layer 114 is between 0mV / nm and 20mV / nm. This relationship of GSP_slope magnitudes allows for further improvement of the luminescence efficiency of the light-emitting device.

[0076] In configuration examples 2 and 3, if the electron transport layer 114 has a stacked structure, it is preferable to compare the GSP_slope of one of the multiple electron transport layers 114 with the GSP_slope of the light-emitting layer 113. Specifically, in the case of a forward-stacked light-emitting device 10A, it is preferable to design the light-emitting device so that the relationship between the magnitudes of the GSP_slopes of the layers with the largest GSP_slope among the multiple electron transport layers 114 is satisfied by comparing the GSP_slope of the layer with the largest GSP_slope with the GSP_slope of the light-emitting layer 113. In the case of an inverted-stacked light-emitting device 10B, it is preferable to design the light-emitting device so that the relationship between the magnitudes of the GSP_slopes of the GSP_slopes of the GSP_slopes of the layers with the smallest GSP_slope among the multiple electron transport layers 114 is satisfied by comparing the GSP_slope of the layer with the smallest GSP_slope with the GSP_slope of the light-emitting layer 113.

[0077] Furthermore, in Configuration Example 3, if the hole transport layer 112 has a stacked structure, it is preferable to compare the GSP_slope of one of the multiple hole transport layers 112 with the GSP_slope of the light-emitting layer 113. Specifically, in the case of a forward-stacked light-emitting device 10A, it is preferable to design the light-emitting device so that the relationship between the magnitudes of the GSP_slope in Configuration Example 3 is satisfied by comparing the GSP_slope of the layer with the largest GSP_slope among the multiple hole transport layers 112 with the GSP_slope of the light-emitting layer 113. In the case of an inverted-stacked light-emitting device 10B, it is preferable to design the light-emitting device so that the relationship between the magnitudes of the GSP_slope in Configuration Example 3 is satisfied by comparing the GSP_slope of the layer with the smallest GSP_slope among the multiple hole transport layers 112 with the GSP_slope of the light-emitting layer 113.

[0078] Furthermore, in Configuration Examples 1 to 3, if the light-emitting layer 113 has a stacked structure, it is preferable to compare the GSP_slope of one of the multiple light-emitting layers 113 with the GSP_slope of the hole transport layer 112 or electron transport layer 114. Specifically, in the case of a forward-stacked light-emitting device 10A, it is preferable to design the light-emitting device so that the relationship between the magnitudes of the GSP_slope of the GSP_slope of the layer with the largest GSP_slope among the multiple light-emitting layers 113 is satisfied by comparing the GSP_slope of the hole transport layer 112 or electron transport layer 114 with the GSP_slope of the hole transport layer 112 or electron transport layer 114. Furthermore, in the case of an inverted-stacked light-emitting device 10B, it is preferable to design the light-emitting device so that the relationship between the magnitudes of the GSP_slope of the GSP_slope of the GSP_slope of the GSP_slope of the GSP_slope of the hole transport layer 112 or electron transport layer 114 is satisfied by comparing the GSP_slope of the layer with the smallest GSP_slope among the multiple light-emitting layers 113 with the GSP_slope of the hole transport layer 112 or electron transport layer 114 with the GSP_slope of

[0079] Furthermore, in a light-emitting device according to one aspect of the present invention, if it has a plurality of hole transport layers 112 and a plurality of electron transport layers 114, in addition to the above configuration examples 1 to 3, it is preferable that, among the layers of the hole transport layer 112, the GSP_slope of the layer located closer to the second electrode 102 is larger than the GSP_slope of the layer located closer to the first electrode 101, and among the layers of the electron transport layer 114, the GSP_slope of the layer located closer to the first electrode 101 is larger than the GSP_slope of the layer located closer to the second electrode 102. For example, if a light-emitting device according to one aspect of the present invention has two hole transport layers (a first hole transport layer 112_1 and a second hole transport layer 112_2) and two electron transport layers (a first electron transport layer 114_1 and a second electron transport layer 114_2), it is preferable that the GSP_slope of the layer located on the second electrode 102 side of the first hole transport layer 112_1 and the second hole transport layer 112_2 is larger than the GSP_slope of the layer located on the first electrode 101 side, and that the GSP_slope of the layer located on the first electrode 101 side of the first electron transport layer 114_1 and the second electron transport layer 114_2 is larger than the GSP_slope of the layer located on the second electrode 102 side.

[0080] In the case of the sequentially stacked light-emitting device 10A shown in Figure 4(A), of the first hole transport layer 112_1 and the second hole transport layer 112_2, the layer located on the second electrode 102 side is the first hole transport layer 112_1, and the layer located on the first electrode 101 side is the second hole transport layer 112_2. Also, of the first electron transport layer 114_1 and the second electron transport layer 114_2, the layer located on the first electrode 101 side is the first electron transport layer 114_1, and the layer located on the second electrode 102 side is the second electron transport layer 114_2. In other words, in the case of the sequentially stacked light-emitting device 10A shown in Figure 4(A), in addition to the above configuration examples 1 to 3, it is more preferable to have a configuration in which the GSP_slope of the first hole transport layer 112_1 is larger than the GSP_slope of the second hole transport layer 112_2, and the GSP_slope of the first electron transport layer 114_1 is larger than the GSP_slope of the second electron transport layer 114_2.

[0081] As a result, as shown in Figure 4(A), a negative interfacial charge 50b_1 can be considered to remain at the interface between the first hole transport layer 112_1 and the second hole transport layer 112_2. This negative interfacial charge 50b_1 attracts holes from the first electrode 101 side to the interface, making it possible to effectively apply an electric field to the light-emitting layer 113. Furthermore, a positive interfacial charge 50a_1 can be considered to remain at the interface between the first electron transport layer 114_1 and the second electron transport layer 114_2. This positive interfacial charge 50a_1 attracts electrons from the second electrode 102 side to the interface, making it possible to effectively apply an electric field to the light-emitting layer 113. Therefore, it becomes easier to effectively apply an electric field to the light-emitting layer 113, which allows the driving voltage of the light-emitting device to be reduced.

[0082] On the other hand, in the inverted stacking type light-emitting device 10B shown in Figure 4(B), of the first hole transport layer 112_1 and the second hole transport layer 112_2, the layer located on the second electrode 102 side refers to the second hole transport layer 112_2, and the layer located on the first electrode 101 side refers to the first hole transport layer 112_1. Also, of the first electron transport layer 114_1 and the second electron transport layer 114_2, the layer located on the second electrode 102 side refers to the first electron transport layer 114_1, and the layer located on the first electrode 101 side refers to the second electron transport layer 114_2. In other words, in the case of the inverted stacking type light-emitting device 10B shown in Figure 4(B), in addition to the above configuration examples 1 to 3, it is more preferable to have a configuration in which the GSP_slope of the second hole transport layer 112_2 is larger than the GSP_slope of the first hole transport layer 112_1, and the GSP_slope of the second electron transport layer 114_2 is larger than the GSP_slope of the first electron transport layer 114_1.

[0083] As a result, as shown in Figure 4(B), a negative interfacial charge 50b_1 can be considered to remain at the interface between the first hole transport layer 112_1 and the second hole transport layer 112_2. This negative interfacial charge 50b_1 attracts holes to the interface from the second electrode 102 side, making it possible to effectively apply an electric field to the light-emitting layer 113. Furthermore, a positive interfacial charge 50a_1 can be considered to remain at the interface between the first electron transport layer 114_1 and the second electron transport layer 114_2. This positive interfacial charge 50a_1 attracts electrons to the interface from the first electrode 101 side, making it possible to effectively apply an electric field to the light-emitting layer 113. Therefore, it becomes easier to effectively apply an electric field to the light-emitting layer 113, which allows the driving voltage of the light-emitting device to be reduced.

[0084] <How to find GSP_slope> Here, we will explain how to determine the GSP_slope of a film formed by vacuum deposition of an organic compound.

[0085] The phenomenon that the surface potential of the vapor deposition film increases in proportion to the film thickness is called the giant surface potential as described above. Generally, when the surface potential of the vapor deposition film measured by the Kelvin probe is plotted in the film thickness direction, the slope is discussed as the magnitude of the giant surface potential, that is, GSP_slope (mV / nm). However, when two different layers are laminated, the charge density (mC / m 2 ) accumulated at the interface changes in relation to GSP, and GSP_slope can be estimated by utilizing this fact.

[0086] Non-Patent Document 1 shows that when organic thin films (thin film 1 and thin film 2. Here, thin film 1 is located on the anode side and thin film 2 is located on the cathode side. Also, the anode is located on the substrate side.) with different spontaneous polarizations are laminated and a voltage is applied, the following equation holds when the carriers accumulated at the interface are holes.

[0087]

Equation

[0088]

Equation

[0089] In Equation (1), σ if_h is the interfacial charge density, V i is the hole injection voltage, V bi is the threshold voltage, d2 is the film thickness of thin film 2, and ε2 is the dielectric constant of 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 (wavelength is 633 nm). Thus, from V i , V bi estimated from the capacitance-voltage characteristics, the dielectric constant ε2 of thin film 2 calculated from the refractive index, and the film thickness d2 of thin film 2, the interfacial charge density σ if_h can be obtained using Equation (1).

[0090] Subsequently, in Equation (2), σif_h P is the interfacial charge density. n ε is the spontaneous polarization of a thin film n (where n is 1 or 2) in the direction normal to the substrate. n V is the dielectric constant of the thin film n. n d is the potential of the film surface, n is the thickness of the thin film n. And the potential (V) of the film surface. n ) film thickness (d n The GSP_slope can be calculated from the value obtained by dividing by ). Here, from the above equation (1), the interfacial charge density σ if_h Since this can be determined, the GSP_slope of thin film 1 can be estimated by using a material with a known GSP_slope as thin film 2 and adopting an appropriate dielectric constant.

[0091] Therefore, using tris(8-quinolinolato)aluminum (abbreviated as Alq3), which has a known GSP_slope of 48 (mV / nm), as thin film 2, a measurement device 1 was fabricated and the GSP_slope of 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviated as NPB) was determined, as shown below.

[0092] The device structure of measurement device 1 is shown in Table 1. The cathode layer 1_1 of measurement device 1 was formed by vacuum deposition from the anode side, with a substrate temperature of room temperature and a deposition rate of 0.2 nm / s to 0.6 nm / s. Deposition was carried out without stopping the deposition process between layers. In measurement device 1, layer 2_1 corresponds to thin film 1, and layer 3_1 corresponds to thin film 2. OCHD-003 is an organic compound with electron acceptor properties.

[0093] When fabricating the measurement device, the deposition rate of each layer is preferably 3 nm / min to 600 nm / min. Furthermore, the film thickness of each layer in the measurement device is preferably 3 nm to 500 nm, and more preferably 50 nm to 300 nm.

[0094] Furthermore, the capacitance-voltage characteristics of the measurement device 1 are shown in Figure 28.

[0095] [Table 1]

[0096] Table 2 shows the Hole injection voltage V of the measuring device 1, which was determined using Figure 28 and equations (1) and (2). i , threshold voltage V bi , interfacial charge density σ if_h , GSP_slope and the refractive index n of the NPB used in the calculation o and the refractive index n of Alq3 o The results are shown. The refractive index was measured using a spectroscopic ellipsometer (M-2000U, manufactured by J.A. Woolam Japan Co., Ltd.).

[0097] [Table 2]

[0098] Furthermore, we fabricated a measurement device 2 with almost the same configuration as measurement device 1, except that the Alq3 film thickness was 80 nm, and confirmed that the hole injection voltage shifted to a lower voltage than that of measurement device 1. This suggests that in such a device, holes are injected first, and charge accumulates at the interface with Alq3. We also used measurement device 2 to estimate the GSP_slope in the same way as measurement device 1 and confirmed that the same results were obtained.

[0099] Furthermore, the threshold voltage V can be obtained from the capacitance-voltage characteristics. bi If it is difficult to estimate, the threshold voltage estimated from the current density-voltage characteristics may be used.

[0100] Figure 29 shows the current density-voltage characteristics of measuring device 1.

[0101] V estimated from current density-voltage characteristics bi The voltage was 2.0V, which was the same value as the one estimated from the capacitance-voltage characteristics.

[0102] In this way, by fabricating a device in which an Alq3 film with a known GSP_slope and a film formed with an organic compound whose GSP_slope is to be determined are stacked, and measuring the capacitance-voltage characteristics, the GSP_slope of the organic compound can be estimated.

[0103] In the above explanation, we described a method for calculating GSP_slope in a configuration where the carriers accumulating at the interface are holes. However, when calculating the GSP_slope of an organic film in a configuration where the carriers accumulating at the interface are electrons, it can be calculated similarly using equations (3) and (4) below. Note that in equations (3) and (4) below, σ if_e This is the interfacial charge density.

[0104]

number

[0105]

number

[0106] It is preferable to select the organic compounds to be used in each layer of the light-emitting device, taking into account the GSP_slope of the vapor-deposited film of the organic compound measured in advance using the measurement method described above.

[0107] In some cases, light-emitting devices use layers co-deposited with multiple types of organic compounds. Since the GSP_slope of a co-deposited layer changes depending on the combination and mixing ratio of the organic compounds, it is ideal to measure the GSP_slope of a film co-deposited with the same combination and mixing ratio of organic compounds as the layer actually used in the light-emitting device, and then select the organic compounds considering this GSP_slope. However, this method requires fabricating different co-deposited films for each combination or mixing ratio of organic compounds and measuring the GSP_slope for each, making the experiments for selecting organic compounds complicated.

[0108] Therefore, in a light-emitting device, if one layer contains multiple types of organic compounds, it is preferable to select the organic compounds by considering the average of the GSP_slope values ​​of the vapor-deposited films of each organic compound, which have been measured in advance, as the GSP_slope of that layer. This makes it relatively easy to select organic compounds while considering GSP_slope.

[0109] However, even if a single layer contains multiple types of organic compounds, if their content differs significantly, the GSP_slope of the vapor-deposited film of the organic compound with the highest content among the multiple organic compounds can be considered the GSP_slope of that layer, and the organic compound can be selected accordingly. For example, if a single layer contains two types of organic compounds, and the content of one organic compound is less than 20% by weight of the total organic compound content in that layer, that organic compound can be judged as a minor component of that layer, and the other, more abundant organic compound can be judged as the main component of that layer, and the GSP_slope of the vapor-deposited film of that main component can be considered the GSP_slope of that layer. Also, if a single layer contains three or four types of organic compounds, and the content of one organic compound is less than 20% by weight of the total organic compound content in that layer, that organic compound can be judged as a minor component of that layer, and the remaining organic compounds can be judged as the main components of that layer, and the average value of the GSP_slope of the vapor-deposited films of each main component can be considered the GSP_slope of that layer.

[0110] Next, the light-emitting layer 113 of the light-emitting device 10A will be explained using Figures 5(A) and 5(B). In the light-emitting layer 113, the host material 118 is present in the largest proportion by weight, and the guest material 119 is dispersed within the host material 118.

[0111] The light-emitting layer 113 shown in Figure 5(A) has a guest material 119 and a host material 118. The guest material 119 is a light-emitting substance. In the light-emitting layer 113, it is preferable that the content of the guest material 119 is less than 20% by weight of the total content of the materials in the layer. Therefore, the light-emitting layer 113 shown in Figure 5(A) can be said to have the host material 118 as the main component and the guest material 119 as a secondary component. Thus, it is preferable to consider the GSP_slope of a light-emitting layer 113 having only one type of host material as the GSP_slope of the deposited film of the main component, the host material 118, and select the organic compounds to be used in each layer of the light-emitting device accordingly.

[0112] The light-emitting layer 113 shown in Figure 5(B) comprises a guest material 119, a first host material 118_1, and a second host material 118_2. In the light-emitting layer 113, the content of the first host material 118_1 and the second host material 118_2 is preferably 25% or more by weight, and the content of the guest material 119 is preferably less than 20% by weight of the total content of the materials in the layer. Therefore, the light-emitting layer 113 shown in Figure 5(B) can be said to have two types of host materials (first host material 118_1 and second host material 118_2) as main components and a guest material 119 as a minor component. Therefore, it is preferable to select the organic compounds to be used in each layer of the light-emitting device by considering the GSP_slope of the light-emitting layer 113, which mainly consists of the first host material 118_1 and the second host material 118_2, as the average value of the GSP_slope of the deposited film of the first host material 118_1 and the GSP_slope of the deposited film of the second host material 118_2.

[0113] In one embodiment of the present invention, it is particularly preferable to use a fluorescent material as the guest material 119 in the light-emitting device.

[0114] Furthermore, as shown in Figures 5(C) and 5(D), the hole transport layer 112 is a layer having organic compound 112C as its main component, and the electron transport layer 114 is a layer having organic compound 114C as its main component. Although not shown, the first hole transport layer 112_1 is a layer having organic compound 112_1C as its main component, the second hole transport layer 112_2 is a layer having organic compound 112_2C as its main component, the first electron transport layer 114_1 is a layer having organic compound 114_1C as its main component, and the second electron transport layer 114_2 is a layer having organic compound 114_2C as its main component.

[0115] Furthermore, if the light-emitting layer 113 has two types of host materials (a first host material 118_1 and a second host material 118_2) as its main components, the GSP_slope of the vapor-deposited film of the main component of the light-emitting layer 113 refers to the average value of the GSP_slope of the vapor-deposited film of the first host material 118_1 and the GSP_slope of the vapor-deposited film of the second host material 118_2.

[0116] When applying Configuration Examples 1 to 3 to the light-emitting devices 10A and 10B, it is preferable to select the organic compound to be used in each layer as shown in the following example.

[0117] When applying Configuration Example 1 to light-emitting devices 10A and 10B having a hole transport layer 112 and an electron transport layer 114 (see Figures 1(A) and 1(B)), it is preferable that the GSP_slope of the main component of the deposited film of the layer located on the second electrode 102 side of the light-emitting layer 113 and hole transport layer 112 is smaller than the GSP_slope of the main component of the deposited film of the layer located on the first electrode 101 side.

[0118] For example, in a sequentially stacked light-emitting device 10A (see Figure 1(A)), if the light-emitting layer 113 has a configuration in which one type of host material 118 is the main component (see Figure 5(A)), it is preferable that the GSP_slope of the deposited film of the host material 118 is smaller than the GSP_slope of the deposited film of the organic compound 112C, and it is more preferable that the difference between the GSP_slope of the deposited film of the host material 118 and the GSP_slope of the deposited film of the organic compound 112C is 0mV / nm or more and 20mV / nm or less. Furthermore, if the light-emitting layer 113 has a configuration having two types of host materials (a first host material 118_1 and a second host material 118_2) (see Figure 5(B)), it is preferable that the average value of the GSP_slope of the deposited film of the first host material 118_1 and the deposited film of the second host material 118_2 is smaller than the GSP_slope of the deposited film of the organic compound 112C. More preferably, the difference between the average value of the GSP_slope of the deposited film of the first host material 118_1 and the deposited film of the second host material 118_2 and the GSP_slope of the deposited film of the organic compound 112C is 0 mV / nm or more and 20 mV / nm or less. This makes it possible to increase the luminescence efficiency of the light-emitting device.

[0119] When applying Configuration Example 2 to light-emitting devices 10A and 10B having a hole transport layer 112 and an electron transport layer 114 (see Figures 2(A) and 2(B)), it is preferable that the GSP_slope of the main component of the deposited film of the layer located on the first electrode 101 side of the light-emitting layer 113 and electron transport layer 114 is smaller than the GSP_slope of the main component of the deposited film of the layer located on the second electrode 102 side.

[0120] For example, in a sequentially stacked light-emitting device 10A (see Figure 2(A)), if the light-emitting layer 113 has a configuration in which one type of host material 118 is the main component (see Figure 5(A)), it is preferable that the GSP_slope of the deposited film of the host material 118 is smaller than the GSP_slope of the deposited film of the organic compound 114C, and it is more preferable that the difference between the GSP_slope of the deposited film of the host material 118 and the GSP_slope of the deposited film of the organic compound 114C is 0mV / nm or more and 20mV / nm or less. Furthermore, if the light-emitting layer 113 has a configuration having two types of host materials (a first host material 118_1 and a second host material 118_2) (see Figure 5(B)), it is preferable that the average value of the GSP_slope of the deposited film of the first host material 118_1 and the deposited film of the second host material 118_2 is smaller than the GSP_slope of the deposited film of the organic compound 114C. More preferably, the difference between the average value of the GSP_slope of the deposited film of the first host material 118_1 and the deposited film of the second host material 118_2 and the GSP_slope of the deposited film of the organic compound 114C is 0 mV / nm or more and 20 mV / nm or less. This makes it possible to increase the luminescence efficiency of the light-emitting device.

[0121] When configuration example 3 is applied to light-emitting devices 10A and 10B having a hole transport layer 112 and an electron transport layer 114 (see Figures 3(A) and 3(B)), it is preferable that the GSP_slope of the main component of the deposited film of the layer located on the second electrode 102 side of the light-emitting layer 113 and hole transport layer 112 is smaller than the GSP_slope of the main component of the deposited film of the layer located on the first electrode 101 side of the light-emitting layer 113 and electron transport layer 114, and that the GSP_slope of the main component of the deposited film of the layer located on the first electrode 101 side of the light-emitting layer 113 and electron transport layer 114 is smaller than the GSP_slope of the main component of the deposited film of the layer located on the second electrode 102 side.

[0122] For example, in a sequentially stacked light-emitting device 10A (see Figure 3(A)), if the light-emitting layer 113 has a configuration in which one type of host material 118 is the main component (see Figure 5(A)), it is preferable that the GSP_slope of the deposited film of the host material 118 is smaller than the GSP_slope of the deposited film of organic compound 112C and the GSP_slope of the deposited film of organic compound 114C. In this case, it is more preferable that the difference between the GSP_slope of the deposited film of the host material 118 and the GSP_slope of the deposited film of organic compound 112C and the GSP_slope of the deposited film of organic compound 114C is 0mV / nm or more and 20mV / nm or less. Furthermore, if the light-emitting layer 113 has a configuration having two types of host materials (a first host material 118_1 and a second host material 118_2) (see Figure 5(B)), it is preferable that the average value of the GSP_slope of the vapor-deposited film of the first host material 118_1 and the GSP_slope of the vapor-deposited film of the second host material 118_2 is smaller than the GSP_slope of the vapor-deposited film of organic compound 112C and the GSP_slope of the vapor-deposited film of organic compound 114C. In this case, it is more preferable that the difference between the average value of the GSP_slope of the vapor-deposited film of the first host material 118_1 and the GSP_slope of the vapor-deposited film of the second host material 118_2 and the GSP_slope of the vapor-deposited film of organic compound 112C and the GSP_slope of the vapor-deposited film of organic compound 114C is 0mV / nm or more and 20mV / nm or less. This can increase the luminous efficiency of the light-emitting device.

[0123] In addition to the above, in light-emitting devices 10A and 10B (see Figures 4(A) and 4(B)) having two hole transport layers (first hole transport layer 112_1 and second hole transport layer 112_2) and two electron transport layers (first electron transport layer 114_1 and second electron transport layer 114_2), it is more preferable that the GSP_slope of the main component of the deposited film of the layer located on the second electrode 102 side of the first hole transport layer 112_1 and second hole transport layer 112_2 is greater than the GSP_slope of the main component of the deposited film of the layer located on the first electrode 101 side of the first electrode 101 side of the first electron transport layer 114_1 and second electron transport layer 114_2 is greater than the GSP_slope of the main component of the deposited film of the layer located on the second electrode 102 side of the first electron transport layer 114_1 and second electron transport layer 114_2.

[0124] For example, in a sequentially stacked light-emitting device 10A (see Figure 4(A)) having two hole transport layers (a first hole transport layer 112_1 and a second hole transport layer 112_2) and two electron transport layers (a first electron transport layer 114_1 and a second electron transport layer 114_2), it is more preferable to have a configuration in which the GSP_slope of the evaporated film of organic compound 112_1C is larger than the GSP_slope of the evaporated film of organic compound 112_2C, and the GSP_slope of the evaporated film of organic compound 114_1C is larger than the GSP_slope of the evaporated film of organic compound 114_2C.

[0125] As shown in the examples above, by selecting the organic compounds used in each layer, the luminescence efficiency of light-emitting devices 10A and 10B can be increased and the driving voltage can be reduced. However, the configuration of the light-emitting device in one aspect of the present invention is not limited to the examples shown above.

[0126] For example, when using a layer in which multiple types of organic compounds are co-deposited in one or more layers of the hole transport layer 112 and electron transport layer 114, the GSP_slope of a film co-deposited with the same combination of organic compounds and the same mixing ratio can be measured in advance, and the organic compounds can be selected considering this GSP_slope. Alternatively, as described above, the average value of the GSP_slope of the deposited films of each organic compound measured in advance can be considered as the GSP_slope of the layer in which multiple types of organic compounds are co-deposited, and the organic compounds can be selected accordingly. Furthermore, as described above, if the content of multiple types of organic compounds in the layer differs significantly, the organic compound with the highest content among the multiple types of organic compounds can be judged as the main component, and the GSP_slope of the deposited film of that main component can be considered as the GSP_slope of the layer, and the organic compounds can be selected accordingly. When two types of organic compounds are contained in one layer, or when three or four types of organic compounds are contained in one layer, the guidelines for the content to be considered as the main component or minor component are as described above, so they are omitted here.

[0127] Furthermore, for example, in the case of a light-emitting device having three or more hole transport layers 112 and three or more electron transport layers 114, the GSP_slope of the vapor-deposited film of the organic compound used in the layer of the three or more hole transport layers 112 that is closer to the second electrode 102 is greater than the GSP_slope of the organic compound used in the layer of the three or more hole transport layers 112 that is closer to the first electrode 101, and the GSP_slope of the vapor-deposited film of the organic compound used in the layer of the three or more electron transport layers 114 that is closer to the first electrode 101 is higher than the GSP_slope of the vapor-deposited film of the organic compound used in the layer of the second electrode 102.

[0128] Furthermore, in addition to the above configuration, if the refractive index of the hole transport layer 112 and the electron transport layer 114 is made smaller in one aspect of the present invention, the light extraction efficiency can be further increased, thereby realizing a very good light-emitting device with high luminous efficiency and low driving voltage.

[0129] Therefore, it is even more preferable to select the organic compounds to be used in each layer of the light-emitting device by considering the refractive index of the organic compound film measured in advance, in addition to the GSP_slope.

[0130] Furthermore, if a single layer contains multiple types of organic compounds, the refractive index of films prepared with the same combination of organic compounds and the same mixing ratio can be measured in advance, and the selection of organic compounds can be made considering this refractive index. Alternatively, the refractive index of the layer can be considered to be the average of the refractive indices of the films of each organic compound measured in advance, and the selection of organic compounds can be made based on this average.

[0131] However, even if a single layer contains multiple types of organic compounds, if their content differs significantly, the refractive index of the film of the organic compound with the highest content among the multiple organic compounds can be considered as the refractive index of the layer, and the selection of organic compounds can be made accordingly. For example, if a single layer contains two types of organic compounds, and the content of one organic compound is less than 20% by weight of the total organic compound content in that layer, that organic compound can be excluded, and the refractive index of the film of the other organic compound can be considered as the refractive index of the layer. Also, if a single layer contains three or more types of organic compounds, and the content of one organic compound is less than 20% by weight of the total organic compound content in that layer, that organic compound can be excluded, and the average refractive index of the films of the remaining organic compounds can be considered as the refractive index of the layer.

[0132] Furthermore, the refractive index of the light-emitting layer 113 (see Figure 5(A)) having only one type of host material can be considered as the refractive index of the film of the host material 118, and the organic compounds to be used in each layer of the light-emitting device can be selected accordingly.

[0133] Furthermore, the refractive index of the light-emitting layer 113 (see Figure 5(B)) having two types of host materials can be considered as the average value of the refractive index of the film of the first host material 118_1 and the refractive index of the film of the second host material 118_2, allowing for the selection of organic compounds to be used in each layer of the light-emitting device.

[0134] Therefore, in addition to considering the GSP_slope, when designing the hole transport layer 112 and electron transport layer 114 in light-emitting devices 10A and 10B to have low refractive indices, the light extraction efficiency of the light-emitting devices can be increased by selecting the organic compounds used in each layer, as shown in the following example.

[0135] For example, in light-emitting devices 10A and 10B (see Figures 1(A) to 3(B)) having a hole transport layer 112 and an electron transport layer 114, if the light-emitting layer 113 has a configuration in which only one type of host material 118 is present (see Figure 5(A)), it is even more preferable that at the peak wavelength of the electroluminescence spectrum of the light-emitting device, at least one of the refractive indices of the film of organic compound 112C and the film of organic compound 114C is lower than the refractive index of the film of the host material 118, and it is even more preferable that the refractive indices of the two films are lower than the refractive index of the film of the host material 118. Furthermore, if the light-emitting layer 113 has a configuration having two types of host materials (a first host material 118_1 and a second host material 118_2) (see Figure 5(B)), it is even more preferable that at the peak wavelength of the electroluminescence spectrum of the light-emitting device, at least one of the refractive index of the film of organic compound 112C and the refractive index of the film of organic compound 114C is lower than the average value of the refractive index of the film of the first host material 118_1 and the refractive index of the film of the second host material 118_2, and it is even more preferable that the refractive index of the two films is lower than the average value of the refractive index of the film of the first host material 118_1 and the refractive index of the film of the second host material 118_2. In any case, it is even more preferable that at the peak wavelength of the electroluminescence spectrum of the light-emitting device, at least one of the refractive index of the film of organic compound 112C and the refractive index of the film of organic compound 114C is 1.75 or less, and it is even more preferable that the refractive index of the two films is 1.75 or less.

[0136] Furthermore, for example, in light-emitting devices 10A and 10B (see Figures 4(A) and 4(B)) having two hole transport layers (first hole transport layer 112_1 and second hole transport layer 112_2) and two electron transport layers (first electron transport layer 114_1 and second electron transport layer 114_2), if the light-emitting layer 113 has a configuration in which only one type of host material 118 is present (see Figure 5(A)), then at the peak wavelength of the electroluminescence spectrum of the light-emitting device, organic compound 112_1C It is even more preferable that at least one of the refractive indices of the film, the refractive index of the film of organic compound 112_2C, the refractive index of the film of organic compound 114_1C, and the refractive index of the film of organic compound 114_2C is lower than the refractive index of the film of the host material 118, and it is even more preferable that the refractive indices of two or more films selected from the film of organic compound 112_1C, the film of organic compound 112_2C, the film of organic compound 114_1C, and the film of organic compound 114_2C are lower than the refractive index of the film of the host material 118. Furthermore, if the light-emitting layer 113 has a configuration having two types of host materials (a first host material 118_1 and a second host material 118_2) (see Figure 5(B)), it is even more preferable that at least one of the refractive indices of the film of organic compound 112_1C, the film of organic compound 112_2C, the film of organic compound 114_1C, and the film of organic compound 114_2C is lower than the average value of the refractive indices of the film of the first host material 118_1 and the film of the second host material 118_2 at the peak wavelength of the electroluminescence spectrum of the light-emitting device. It is even more preferable that the refractive indices of two or more films selected from the films of organic compound 112_1C, the film of organic compound 112_2C, the film of organic compound 114_1C, and the film of organic compound 114_2 are lower than the average value of the refractive indices of the film of the first host material 118_1 and the film of the second host material 118_2.Furthermore, in all cases, it is even more preferable that at least one of the refractive indices of the film of organic compound 112_1C, the film of organic compound 112_2C, the film of organic compound 114_1C, and the film of organic compound 114_2C is 1.75 or less at the peak wavelength of the electroluminescence spectrum of the light-emitting device, and it is even more preferable that the refractive indices of two or more films selected from the film of organic compound 112_1C, the film of organic compound 112_2C, the film of organic compound 114_1C, and the film of organic compound 114_2C is 1.75 or less.

[0137] Furthermore, if the electroluminescence spectrum of the light-emitting device has multiple peaks, it is preferable that the refractive index at the wavelength of at least one peak or the maximum peak wavelength has the above configuration. Alternatively, the refractive index at the peak wavelength of the emission spectrum of the light-emitting material used in the light-emitting device may also have the above configuration. The emission spectrum of the light-emitting material can be measured in thin film or solution.

[0138] Furthermore, as a material with a low refractive index, it is preferable to use an organic compound in which an alkyl group, which has a lower polarizability than the aromatic skeleton, is bonded to the aromatic skeleton. In particular, it is more preferable to use an organic compound having at least one group selected from chain alkyl groups having 2 to 10 carbon atoms and cycloalkyl groups having 6 to 12 carbon atoms.

[0139] Specific examples of organic compounds that can be used in the light-emitting layer 113, hole transport layer 112, and electron transport layer 114 of a light-emitting device according to one aspect of the present invention are described below. It is preferable to select an organic compound that satisfies the above conditions from the following specific examples or known organic compounds to fabricate a light-emitting device according to one aspect of the present invention. The GSP_slope and paraphotometric refractive index of the vapor-deposited film of each organic compound whose structural formula is shown below are shown in Example 1 or Example 2.

[0140] In one embodiment of the present invention, the host material 118 of the light-emitting layer 113 of the light-emitting device can be an organic compound having hole transport properties, an organic compound having electron transport properties, a bipolar material, or the like.

[0141] In particular, in the case of a light-emitting device that uses a fluorescent material in the light-emitting layer and utilizes TTA to enhance the light-emitting efficiency, it is more preferable to use a condensed polycyclic aromatic compound such as anthracene derivatives, tetracene derivatives, phenanthrene derivatives, pyrene derivatives, chrysene derivatives, or dibenzo[g,p]chrysene derivatives as the host material 118, which is an organic compound with a high singlet excitation energy level and a low triplet excitation energy level.

[0142] Specific examples of host material 118 include 2,9-di(1-naphthyl)-10-phenylanthracene (abbreviation: 2αN-αNPhA) and 1-[10-(phenyl-2,3,4,5,6-d5)-9-anthryl]benzo[b]naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA-02-d5). Their structural formulas are shown below.

[0143] [ka]

[0144] Furthermore, in the case of a light-emitting device that uses a fluorescent material in the light-emitting layer and utilizes TTA to enhance luminescence efficiency, it is preferable that the lowest singlet excitation energy level (S1 level) of the host material 118 is higher than the S1 level of the fluorescent material, and the lowest triplet excitation energy level (T1 level) of the host material 118 is lower than the T1 level of the fluorescent material. It is even more preferable that the energy difference between the HOMO level of the host material 118 and the HOMO level of the fluorescent material is 0.25 eV or more. In addition, it is preferable that the concentration of the fluorescent material in the light-emitting layer is 0.5 wt% to 25 wt% relative to the host material 118. With this configuration, holes are more easily trapped in the light-emitting layer, carriers recombine locally in the region on the hole transport layer side of the light-emitting layer, and the exciton density increases, thereby improving the efficiency of TTA. Furthermore, as another configuration to enhance luminescence efficiency using TTA, it is more preferable that the LUMO level of the fluorescent material is lower than the LUMO level of the host material 118. With this configuration, electrons are more easily trapped in the luminescence layer, carriers recombine locally in the region on the hole transport layer side of the luminescence layer, and the exciton density increases, thereby improving the efficiency of TTA.

[0145] The HOMO and LUMO levels used in this specification can be determined by electrochemical measurements. Typical examples of electrochemical measurements include cyclic voltammetry (CV) and differential pulse voltammetry (DPV).

[0146] In cyclic voltammetry (CV) measurements, the values ​​of the HOMO and LUMO levels (E) are obtained by changing the oxidation peak potential (E) relative to the reference electrode. pa ), and reduction peak potential (E pc Based on this, it can be calculated. In the measurement, the HOMO level is determined from the positive potential scan, and the LUMO level is determined from the negative potential scan. The scan speed in the measurement is set to 0.1 V / s.

[0147] The specific procedure for calculating the HOMO and LUMO levels is described below. The oxidation peak potential (E) is obtained from the cyclic voltammogram of the material. pa ), and reduction peak potential (E pc ) from the standard oxidation-reduction potential (E o )(=(E pa +E pc ) / 2) is calculated, and the potential energy (E) of the reference electrode with respect to the vacuum level is calculated. x By subtracting from ), the values ​​of the HOMO level and LUMO level (E) (=E x -E o ) can be calculated for each of these.

[0148] Note that the above shows the case where a reversible redox wave is obtained, but when an irreversible redox wave is obtained, the HOMO level is calculated using the oxidation peak potential (E pa The reduced peak potential (E) is obtained by subtracting a certain value (0.1 eV) from ). pc ) Assuming the standard oxidation-reduction potential (E o ) is calculated to one decimal place. Also, the reduction peak potential (E) is used to calculate the LUMO level. pc The oxidation peak potential (E) is calculated by adding a constant value (0.1eV) to the value obtained). pa ) Assuming the standard oxidation-reduction potential (E o Calculate the result to one decimal place.

[0149] For the T1 level, the phosphorescence component (phosphor spectrum) of the PL spectrum observed at low temperatures (e.g., any temperature in the range of 4K to 80K) can be used as an indicator. For example, if the PL spectrum (phosphor spectrum) is measured at a measurement temperature of 10K, the energy at the short-wavelength emission edge of that phosphorescence spectrum can be considered as the T1 level. For the S1 level, the PL spectrum measured at low temperatures (e.g., any temperature in the range of 4K to 80K) or at room temperature can be used as an indicator. For example, if the PL spectrum is measured at room temperature, the energy at the short-wavelength emission edge can be considered as the S1 level. Furthermore, if both a fluorescence spectrum and a phosphorescence spectrum are observed in the PL spectrum measured at low temperatures, the energy at the shortest wavelength emission edge of the PL spectrum (fluorescence spectrum) can be considered as the S1 level. Additionally, the absorption spectrum measured at room temperature can be used as an indicator of the S1 level of a fluorescent material. For example, if the absorption spectrum is measured at room temperature, the energy at the long-wavelength absorption edge can be considered as the S1 level.

[0150] Furthermore, the emission edge on the short-wavelength side of a PL spectrum can be calculated by drawing a tangent line at the point where the absolute value of the slope on the short-wavelength side of the peak (or shoulder peak) observed at the shortest wavelength of the PL spectrum is maximum, and then calculating the value from the intersection of this tangent line with the horizontal axis (wavelength) or baseline. Similarly, the emission edge on the long-wavelength side of an absorption spectrum can be calculated by drawing a tangent line at the point where the absolute value of the slope on the long-wavelength side of the peak (or shoulder peak) observed at the longest wavelength of the absorption spectrum is maximum, and then calculating the value from the intersection of this tangent line with the horizontal axis (wavelength) or baseline.

[0151] It is preferable to use an organic compound having hole-transporting properties as the organic compound used in the hole transport layer 112 of the light-emitting device. More specifically, it is preferable to use an organic compound having an aromatic skeleton or a heteroaromatic skeleton, such as a π-electron-rich heteroaromatic ring or an aromatic amine skeleton, and it is even more preferable to use an organic compound having an aromatic skeleton or a heteroaromatic skeleton that contains a nitrogen element and has high symmetry. Examples of π-electron-rich heteroaromatic rings include heteroaromatic rings containing a pyrrole skeleton, heteroaromatic rings containing a furan skeleton, and heteroaromatic rings containing a thiophene skeleton. Examples of aromatic skeletons or heteroaromatic skeletons that contain a nitrogen element and have high symmetry include a triphenylamine skeleton and a 3,3'-bicarbazole skeleton.

[0152] Specific examples of organic compounds used in the hole transport layer 112 include N-(3',5'-diter-butylbiphenyl-4-yl)-N-(3',5'-diter-butylbiphenyl-2-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: dmmtBuopBBAF), N-(3',5'-diter-butylbiphenyl-4-yl)-N-(biphenyl-2-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBuBioFBi), N-(biphenyl-2-yl)-N-(3'',5',5''-tri-tert-butyl-[1,1':3',1''-terphenyl]-4-yl)-9,9-dimethyl- Examples of organic compounds having a π-electron-rich heteroaromatic ring or aromatic amine skeleton include 9H-fluoren-2-amine (abbreviation: mmtBumTPoFBi-04), N,N-bis(biphenyl-4-yl)-9,9'-spirobi[9H-fluoren]-2-amine (abbreviation: BBASF), N-phenyl-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-9,9'-spirobi[9H-fluoren]-2-amine (abbreviation: PCBASF), and N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF). Their structural formulas are shown below.

[0153] [ka]

[0154] Of the organic compounds mentioned above, dmmtBuopBBAF, mmtBuBioFBi, and mmtBumTPoFBi-04 are organic compounds having at least one group selected from chain alkyl groups having 2 to 10 carbon atoms and cycloalkyl groups having 6 to 12 carbon atoms, and therefore have a low refractive index. For this reason, they are more preferable organic compounds for use in the hole transport layer 112 of light-emitting devices.

[0155] It is preferable to use an organic compound with electron-transporting properties as the organic compound used in the electron transport layer 114. More specifically, an organic compound containing at least one of nitrogen, oxygen, and sulfur atoms and having a highly symmetrical heteroaromatic skeleton is more preferable.

[0156] Specific examples of organic compounds used in the electron transport layer 114 include 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) and 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthryl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: m Pn-mDMePyPTzn), 2-(biphenyl-2-yl)-4-[3-(3,5-dicyclohexylphenyl)-5-(2,6-dimethylpyridine-3-yl)]phenyl-6-phenyl-1,3,5-triazine (abbreviation: oBP-mmchPh-mDMePyPTzn), 2-[3,5-bis(2,6-dimethylpyridine-3-yl)phenyl]-4-(3',5'-di-tert-butylbiphenyl-4-yl)-6-phenyl Nyl-1,3,5-triazine (abbreviation: mmtBuBP-DMePy2PTzn), 2-(2',7'-di-tert-butyl-9,9'-spirobio[9H-fluoren]-2-yl)-4,6-diphenyl-1,3,5-triazine (abbreviation: tBu-SFTzn), 2-[3'-(9,9'-spirobio[9H-fluoren]-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mSFBP) Examples of organic compounds having π-electron-deficient heteroaromatic rings include Tzn, 2,4,6-tris[3'-(pyridine-3-yl)-5'-tert-butyl-biphenyl-3-yl]-1,3,5-triazine (abbreviated as tBu-TmPPPyTz), 2,4,6-tris(3'-(pyridine-3-yl)biphenyl-3-yl)-1,3,5-triazine (abbreviated as TmPPPyTz), and 8-quinolinolatolithium (abbreviated as Liq). Their structural formulas are shown below.

[0157] [ka]

[0158] Of the organic compounds mentioned above, mmtBuPh-mDMePyPTzn, oBP-mmchPh-mDMePyPTzn, mmtBuBP-DMePy2PTzn, tBu-SFTzn, and tBu-TmPPPyTz are organic compounds having at least one group selected from chain alkyl groups having 2 to 10 carbon atoms and cycloalkyl groups having 6 to 12 carbon atoms, and therefore have a low refractive index. For this reason, they are more preferable organic compounds for use in the electron transport layer 114.

[0159] The organic compounds that can be used in the light-emitting device according to one embodiment of the present invention are not limited to the specific examples described above.

[0160] The configuration shown in this embodiment can be used in appropriate combination with the configurations shown in other embodiments.

[0161] (Embodiment 2) In this embodiment, other configurations of a light-emitting device according to one aspect of the present invention will be described with reference to Figures 6(A) to 6(E).

[0162] <Basic structure of a light-emitting device> The basic structure of a light-emitting device will be described. Figure 6(A) shows a light-emitting device with a structure (single structure) having an organic compound layer containing a light-emitting layer between a pair of electrodes. Specifically, it has a structure in which an organic compound layer 103 is sandwiched between the first electrode 101 and the second electrode 102.

[0163] Furthermore, Figure 6(B) shows a light-emitting device with a laminated structure (tandem structure) having multiple (two layers in Figure 6(B)) organic compound layers (103a, 103b) between a pair of electrodes, and a charge generation layer 106 between the organic compound layers. A light-emitting device with a tandem structure can realize a highly efficient light-emitting device without changing the amount of current.

[0164] The charge generation layer 106 has the function of injecting electrons into one organic compound layer (103a or 103b) and holes into the other organic compound layer (103b or 103a) when a potential difference is created between the first electrode 101 and the second electrode 102. Therefore, in Figure 6(B), when a voltage is applied to the first electrode 101 such that the potential is higher than that of the second electrode 102, electrons are injected from the charge generation layer 106 into the organic compound layer 103a and holes are injected into the organic compound layer 103b.

[0165] Furthermore, from the viewpoint of light extraction efficiency, it is preferable that the charge generation layer 106 is transparent to visible light (specifically, the transmittance of visible light to the charge generation layer 106 is 40% or more). In addition, the charge generation layer 106 can function even if its conductivity is lower than that of the first electrode 101 and the second electrode 102.

[0166] Figure 6(C) shows the laminated structure of the organic compound layer 103 of a light-emitting device according to one embodiment of the present invention. In this case, the first electrode 101 functions as an anode and the second electrode 102 functions as a cathode. The organic compound layer 103 has a structure in which a hole injection layer 111, a hole transport layer 112, a light-emitting layer 113, an electron transport layer 114, and an electron injection layer 115 are sequentially laminated on the first electrode 101. The light-emitting layer 113 may be a configuration in which multiple light-emitting layers with different emission colors are laminated. For example, a light-emitting layer containing a red light-emitting substance, a light-emitting layer containing a green light-emitting substance, and a light-emitting layer containing a blue light-emitting substance may be laminated, or laminated via a layer having a carrier transport material. Alternatively, a combination of a light-emitting layer containing a yellow light-emitting substance and a light-emitting layer containing a blue light-emitting substance may be used. However, the laminated structure of the light-emitting layer 113 is not limited to the above. For example, the light-emitting layer 113 may be a structure in which multiple light-emitting layers of the same emission color are stacked. For example, a first light-emitting layer containing a blue light-emitting substance and a second light-emitting layer containing a blue light-emitting substance may be stacked, or a structure in which they are stacked via a layer having a carrier transport material. In the case of a structure in which multiple light-emitting layers of the same emission color are stacked, reliability can be increased compared to a single-layer structure. Also, even when there are multiple organic compound layers as in the tandem structure shown in Figure 6(B), each organic compound layer is stacked sequentially from the anode side as described above. Furthermore, when the first electrode 101 functions as the cathode and the second electrode 102 functions as the anode, the stacking order of the organic compound layers 103 is reversed. Specifically, on the first electrode 101 which functions as the cathode, 111 is an electron injection layer, 112 is an electron transport layer, 113 is a light-emitting layer, 114 is a hole transport layer, and 115 is a hole injection layer.

[0167] The light-emitting layers 113 contained within the organic compound layers (103, 103a, 103b) each contain a light-emitting substance and a combination of multiple substances as appropriate, and can be configured to produce fluorescence emission or phosphorescence emission exhibiting a desired emission color. Alternatively, the light-emitting layers 113 may be arranged in a laminated structure with different emission colors. In this case, the light-emitting substance and other substances used in each laminated light-emitting layer may be made of different materials. Furthermore, a configuration in which different emission colors can be obtained from multiple organic compound layers (103a, 103b) as shown in Figure 6(B) is also possible. In this case as well, the light-emitting substance and other substances used in each light-emitting layer may be made of different materials.

[0168] Furthermore, in a light-emitting device according to one aspect of the present invention, for example, by using a reflective electrode as the first electrode 101 shown in Figure 6(C) and a semi-transparent / semi-reflective electrode as the second electrode 102, and by using a microcavity structure, the light emitted from the light-emitting layer 113 contained in the organic compound layer 103 can be resonated between the two electrodes, thereby strengthening the light emitted from the second electrode 102. Therefore, it is easy to achieve high resolution. In addition, since it is possible to strengthen the light emission intensity in the front direction at a specific wavelength, power consumption can be reduced.

[0169] Furthermore, if the first electrode 101 of the light-emitting device is a reflective electrode consisting of a laminated structure of a reflective conductive material and a translucent conductive material (transparent conductive film), optical adjustment can be performed by controlling the film thickness of the transparent conductive film. Specifically, it is preferable to adjust the optical distance (product of film thickness and refractive index) between the first electrode 101 and the second electrode 102 to be mλ / 2 (where m is an integer of 1 or more) or close to it, with respect to the wavelength λ of light obtained from the light-emitting layer 113.

[0170] Furthermore, in order to amplify the desired light obtained from the light-emitting layer 113 at a desired wavelength (wavelength: λ), it is preferable to adjust the optical distance from the first electrode 101 to the region where light emission from the light-emitting layer 113 is obtained (light-emitting region), and the optical distance from the second electrode 102 to the region where light emission from the light-emitting layer 113 is obtained (light-emitting region), so that they are (2m'+1)λ / 4 (where m' is an integer of 1 or more) or near that value. The light-emitting region referred to here is the region in the light-emitting layer 113 where holes and electrons recombine.

[0171] By performing such optical adjustments, the spectrum of specific monochromatic light obtained from the light-emitting layer 113 can be narrowed, resulting in emission with good color purity.

[0172] However, in the above case, the optical distance between the first electrode 101 and the second electrode 102 can be precisely defined as the total thickness from the reflective region of the first electrode 101 to the reflective region of the second electrode 102. However, since it is difficult to precisely determine the reflective regions of the first electrode 101 and the second electrode 102, the above effect can be sufficiently obtained by assuming that any position on the first electrode 101 and the second electrode 102 is a reflective region. Furthermore, the optical distance between the first electrode 101 and the light-emitting layer can be precisely defined as the optical distance between the reflective region of the first electrode 101 and the light-emitting region of the light-emitting layer. However, since it is difficult to precisely determine the reflective region of the first electrode 101 and the light-emitting region of the light-emitting layer, the above effect can be sufficiently obtained by assuming that any position on the first electrode 101 is a reflective region and any position on the light-emitting layer is a light-emitting region.

[0173] The light-emitting device shown in Figure 6(D) is a light-emitting device with a tandem structure. The tandem structure allows for a light-emitting device capable of high-brightness illumination. Furthermore, compared to a single structure, the tandem structure reduces the current required to achieve the same brightness, thereby improving reliability. It also reduces power consumption.

[0174] The light-emitting device shown in Figure 6(E) is an example of a tandem-structured light-emitting device shown in Figure 6(B). As shown in the figure, it has a structure in which three organic compound layers (103a, 103b, 103c) are stacked with charge generation layers (106a, 106b) in between. Each of the three organic compound layers (103a, 103b, 103c) has a light-emitting layer (113a, 113b, 113c), and the light-emitting colors of each light-emitting layer can be freely combined. For example, light-emitting layer 113a can be blue, light-emitting layer 113b can be red, green, or yellow, and light-emitting layer 113c can be blue. Alternatively, light-emitting layer 113a can be red, light-emitting layer 113b can be blue, green, or yellow, and light-emitting layer 113c can be red.

[0175] In the light-emitting device according to one aspect of the present invention described above, at least one of the first electrode 101 and the second electrode 102 is a light-transmitting electrode (such as a transparent electrode or a semi-transparent / semi-reflective electrode). If the light-transmitting electrode is a transparent electrode, the transmittance of visible light of the transparent electrode shall be 40% or more. If it is a semi-transparent / semi-reflective electrode, the reflectance of visible light of the semi-transparent / semi-reflective electrode shall be 20% or more and 80% or less, preferably 40% or more and 70% or less. Furthermore, the resistivity of these electrodes shall be 1 × 10⁻⁶. -2 It is preferable to keep it below Ω·cm.

[0176] Furthermore, in the light-emitting device according to one aspect of the present invention described above, if one of the first electrode 101 and the second electrode 102 is a reflective electrode (reflective electrode), the visible light reflectance of the reflective electrode is 40% or more and 100% or less, preferably 70% or more and 100% or less. In addition, the resistivity of this electrode is 1 × 10⁻⁶. -2 It is preferable to keep it below Ω·cm.

[0177] <Specific structure of a light-emitting device> Next, a specific structure of a light-emitting device according to one aspect of the present invention will be described. Here, we will use Figure 6(D), which has a tandem structure, for explanation. The same applies to the configuration of the organic compound layer for the single-structure light-emitting devices shown in Figures 6(A) and 6(C). Furthermore, if the light-emitting device shown in Figure 6(D) has a microcavity structure, the first electrode 101 is formed as a reflective electrode, and the second electrode 102 is formed as a semi-transparent / semi-reflective electrode. Thus, one or more desired electrode materials can be used and formed as a single layer or in a stacked configuration. The second electrode 102 is formed by selecting an appropriate material after the organic compound layer 103b has been formed.

[0178] <Materials for light-emitting devices> ≪Luminous layer≫ The light-emitting layers (113, 113a, 113b) are layers containing a light-emitting material. The light-emitting material that can be used in the light-emitting layers (113, 113a, 113b) can be any material that exhibits a light-emitting color such as blue, purple, blue-violet, green, yellow-green, yellow, orange, or red. Furthermore, if there are multiple light-emitting layers, a configuration exhibiting different light-emitting colors can be achieved by using different light-emitting materials in each layer (for example, white light emission obtained by combining complementary light-emitting colors). Additionally, a laminated structure in which each light-emitting layer contains a different light-emitting material is also possible.

[0179] Furthermore, the light-emitting layers (113, 113a, 113b) may contain one or more types of organic compounds (host materials, etc.) in addition to the light-emitting substance (guest material). When multiple host materials are used in the light-emitting layers (113, 113a, 113b), the structure described using Figure 5(B) of Embodiment 1 can be used as the light-emitting layer. In the light-emitting layer, the host material 118 is present in the largest amount by weight, and the guest material 119 is dispersed in the host material 118. Preferably, the T1 level of the host material 118 (first host material 118_1 and second host material 118_2) in the light-emitting layer is higher than the T1 level of the guest material (guest material 119).

[0180] As the first host material 118_1, a material with higher electron transport capabilities than hole transport can be used, 1 × 10 -6 cm 2 It is preferable that the material has an electron mobility of 1 / Vs or higher. As materials that readily accept electrons (materials with electron transport properties), compounds having a π-electron-deficient heteroaromatic ring skeleton, such as nitrogen-containing heteroaromatic compounds, and zinc-based or aluminum-based metal complexes can be used. Examples of compounds having a π-electron-deficient heteroaromatic ring skeleton include oxadiazole derivatives, triazole derivatives, benzimidazole derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, phenanthroline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, and triazine derivatives. Examples of zinc-based or aluminum-based metal complexes include metal complexes having a quinoline ligand, a benzoquinoline ligand, an oxazole ligand, or a thiazole ligand.

[0181] Specifically, examples include metal complexes having a quinoline skeleton or a benzoquinoline skeleton, such as tris(8-quinolinolato)aluminum(III) (abbreviated as Alq), tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviated as Almq3), bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviated as BeBq2), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (abbreviated as BAlq), and bis(8-quinolinolato)zinc(II) (abbreviated as Znq). In addition, metal complexes having oxazole-based or thiazole ligands, such as bis[2-(2-benzoxazolyl)phenolate]zinc(II) (abbreviated as ZnPBO) and bis[2-(2-benzothiazolyl)phenolate]zinc(II) (abbreviated as ZnBTZ), can also be used. Furthermore, in addition to metal complexes, there are also 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviated as PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazole-2-yl]benzene (abbreviated as OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazole-2-yl)phenyl]-9H-carbazole (abbreviated as CO11), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviated as TAZ), and 9-[4-(4,5-diphenyl-4H-1,2,4-triazole-3-yl)phenyl] Heterocyclic compounds such as -9H-carbazole (abbreviation: CzTAZ1), 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), vasophenanthroline (abbreviation: BPhen), vasocuproin (abbreviation: BCP), 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,[h]Quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]Quinoxaline (abbreviation: 2mCzBPDBq), 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]Quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]Quinoxaline n (abbreviation: 7mDBTPDBq-II), 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 2-[3-([3,9'-bi-9H-carbazole]-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzCzPDBq), 4,6-bis[3-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis Heterocyclic compounds having a diazine skeleton, such as [3-(dibenzothiophen-4-yl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II) and 4,6-bis[3-(9H-carbazole-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), and 2-{4-[3-(N-phenyl-9H-carbazole-3-yl)-9H-carbazole-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PC Heterocyclic compounds having a triazine skeleton such as CzPTzn, 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), and heteroaromatic compounds such as 4,4'-bis(5-methylbenzoxazole-2-yl)stilbene (abbreviated as BzOs) can also be used. Among the heterocyclic compounds mentioned above, heterocyclic compounds having a triazine skeleton, a diazine (pyrimidine, pyrazine, pyridazine) skeleton, or a pyridine skeleton are preferred because they are stable and reliable. Furthermore, heterocyclic compounds having these skeletons have high electron transport properties and contribute to reducing the driving voltage. Also, poly(2,5-pyridinediyl) (abbreviation: PPy), poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,High molecular weight compounds such as 5-diyl) (abbreviated as PF-Py) and poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2'-bipyridine-6,6'-diyl)] (abbreviated as PF-BPy) can also be used. The substances described here are mainly 1 × 10, -6 cm 2 The material must have an electron mobility of / Vs or greater. However, any material with higher electron transport capabilities than holes may be used.

[0182] As the second host material 118_2, a combination that can form an excited complex with the first host material 118_1 is preferred. Specifically, it is preferable to have a skeleton with high donor potential, such as a π-electron-rich heteroaromatic ring or an aromatic amine skeleton. Examples of compounds having a π-electron-rich heteroaromatic ring include heteroaromatic compounds such as dibenzothiophene derivatives, dibenzofuran derivatives, and carbazole derivatives. In this case, it is preferable to select the first host material 118_1, the second host material 118_2, and the guest material 119 such that the emission peak of the excited complex formed by the first host material 118_1 and the second host material 118_2 overlaps with the absorption band of the triplet MLCT (Metal to Ligand Charge Transfer) transition of the guest material 119, more specifically, with the absorption band located at the longest wavelength. This makes it possible to create a light-emitting device with dramatically improved luminescence efficiency. However, when a thermally activated delayed fluorescence material is used as the guest material 119, it is preferable that the absorption band located at the longest wavelength is a singlet absorption band.

[0183] As the second host material 118_2, the following hole-transporting materials can be used. As the hole-transporting material, a material with higher hole transport capabilities than electron transport can be used, and 1 × 10⁻⁶ -6 cm 2 It is preferable that the material has a hole mobility of / Vs or greater. Specifically, aromatic amines, carbazole derivatives, aromatic hydrocarbons, stilbene derivatives, etc., can be used. The hole transporting material may also be a polymer compound.

[0184] Examples of materials with high hole transport capabilities include, specifically, aromatic amine compounds such as 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)aminophenyl]-N,N'-diphenyl-4,4'-diaminobiphenyl (abbreviated as DNTPD), and 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviated as DPA3B).

[0185] Furthermore, specific examples of carbazole derivatives include 3-[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviated as PCzDPA1), 3,6-bis[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviated as PCzDPA2), and 3,6-bis[N-(4-diphenylaminophenyl)-N-(1-naphthyl)amino]-9-phenylcarbazole (abbreviated as PCzTP Examples include N2), 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 (abbreviated as PCzPCN1).

[0186] Other carbazole derivatives that can be used include 4,4'-di(N-carbazolyl)biphenyl (abbreviated as CBP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviated as TCPB), 9-[4-(10-phenyl-9-antryl)phenyl]-9H-carbazole (abbreviated as CzPA), and 1,4-bis[4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene.

[0187] Furthermore, aromatic hydrocarbons include, for example, 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), and 2-ter Examples include t-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-butylperylene. In addition, pentacene, coronene, and the like can also be used. Thus, 1 × 10 -6 cm 2 It is more preferable to use aromatic hydrocarbons having a hole mobility of / Vs or higher and having 14 to 42 carbon atoms.

[0188] Aromatic hydrocarbons may also have a vinyl skeleton. Examples of aromatic hydrocarbons having a vinyl skeleton include 4,4'-bis(2,2-diphenylvinyl)biphenyl (abbreviated as DPVBi) and 9,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene (abbreviated as DPVPA).

[0189] In addition, 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), or poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine] (abbreviated as Poly-TPD) can also be used.

[0190] Furthermore, materials with high hole transport capabilities include, for example, 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviated as NPB), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-4,4'-diaminobiphenyl (abbreviated as TPD), 4,4',4''-tris(carbazole-9-yl)triphenylamine (abbreviated as TCTA), 4,4',4''-tris[N-(1-naphthyl)-N-phenylamino]triphenylamine (abbreviated as 1'-TNATA), and 4,4',4 ''-Tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA), 4,4',4''-Tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (abbreviation: m-MTDATA), N,N'-Bis(9,9'-spirobio[9H-fluoren]-2-yl)-N,N'-diphenyl-4,4'-diaminobiphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3' -(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), N-(9,9-dimethyl-9H-fluoren-2-yl)-N-{9,9-dimethyl-2-[N'-phenyl-N'-(9,9-dimethyl-9H-fluoren-2-yl)amino]-9H-fluoren-7-yl}phenylamine (abbreviation: DFLADFL), N-(9,9-dimethyl-2-diphenylamino-9H-fluoren-7-yl)diphenylamine (abbreviation: DPNF), N-(9,9-spirobio[9H- Fluoren]-2-yl)-N,N'N'-triphenyl-1,4-phenylenediamine (abbreviation: DPASF), 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), 4-phenyldiphenyl-(9-phenyl-9H-carbazole-3-yl)amine (abbreviation: PCA1BP), N,N'-bis(9-phenylcarbazole-3-yl)-N,N'-diphenylbenzene-1,3-diamine (abbreviation: PCA2B), N,N',N''-triphenyl-N,N',N''-tris(9-phenylcarbazole-3-yl)benzene-1,3,5-triphenyl Min (abbreviation: PCA3B), N-(9,9-diphenyl-9H-fluoren-2-yl)-N,9-diphenyl-9H-carbazole-3-amine (abbreviation: PCAFLP(2)), N-(9,9-diphenyl-9H-fluoren-2-yl)-N,9-diphenyl-9H-carbazole-2-amine (abbreviation: PCAFLP(2)-02), N-(biphenyl-4-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9-phenyl-9H-carbazole-3-amine (abbreviation: PCBiF), N-(biphenyl 9,9-dimethyl-9H-fluoren-2-amine (abbreviated as PCBBiF), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]fluoren-2-amine (abbreviated as PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-9,9'-spirobio[9H-fluoren]-2-amine (abbreviated as PCBASF), N-(9,9-s Pyrobi[9H-fluoren]-2-yl)-N,9-diphenylcarbazole-3-amine (abbreviation: PCASF), N,N'-diphenyl-N,N'-bis(4-diphenylaminophenyl)spirobi[9H-fluoren]-2,7-diamine (abbreviation: DPA2SF), N-[4-(9H-carbazole-9-yl)phenyl]-N-(4-phenyl)phenylaniline (abbreviation: YGA1BP), N,N'-bis[4-(carbazole-9-yl)phenyl]-N,N'-diphenyl-9,9-dimethylfluoren-2,Aromatic amine compounds such as 7-diamine (abbreviation: YGA2F) can be used. In addition, 3-[4-(1-naphthyl)phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 9-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]phenanthrene (abbreviation: PCPPn), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), 9,9'-bis(biphenyl-4-yl)-3,3'-bi-9H-carbazole (abbreviation: BisBPCz), 9-(biphenyl-3-yl)-9'-(biphenyl -4-yl)-9H,9'H-3,3'-bicarbazole (abbreviation: mBPCCBP), 9-(2-naphthyl)-9'-phenyl-3,3'-bi-9H-carbazole (abbreviation: βNCCP), 9-(3-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviation: βNCCmBP), 9-(4-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviation: βNCCBP), 9,9'-di-2-naphthyl-3,3' -9H,9'H-bicarbazole (abbreviation: BisβNCz), 9-[3-(triphenylsilyl)phenyl]-3,9'-bi-9H-carbazole (abbreviation: PSiCzCz), 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 3,6-di(9H-carbazol-9-yl)-9-phenyl-9H-carbazole (abbreviation: PhCzGI), 2,8-di (9H-carbazole-9-yl)dibenzothiophene (abbreviation: Cz2DBT), 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II), 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II), 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,Amine compounds such as 8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviated as DBTFLP-III), 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviated as DBTFLP-IV), and 4-[3-(triphenylene-2-yl)phenyl]dibenzothiophene (abbreviated as mDBTPTp-II), as well as carbazole compounds, thiophene compounds, furan compounds, fluorene compounds, triphenylene compounds, and phenanthrene compounds can be used. Among the above-mentioned compounds, compounds having a pyrrole skeleton, furan skeleton, thiophene skeleton, or aromatic amine skeleton are preferred because they are stable and reliable. Furthermore, compounds having these skeletons exhibit high hole transportability and contribute to reducing the driving voltage.

[0191] Furthermore, when an organic compound having electron-transporting properties is used as the first host material 118_1 and an organic compound having hole-transporting properties is used as the second host material 118_2, it is preferable that the HOMO level of the organic compound having hole-transporting properties is at or above the HOMO level of the organic compound having electron-transporting properties. In addition, it is preferable that the LUMO level of the organic compound having hole-transporting properties is at or above the LUMO level of the organic compound having electron-transporting properties, as this allows for more efficient formation of the excited complex.

[0192] There are no particular limitations on the guest material 119 that can be used in the light-emitting layers (113, 113a, 113b). A light-emitting material that converts singlet excitation energy into visible light emission, or a light-emitting material that converts triplet excitation energy into visible light emission, can be used.

[0193] <<Luminescent material that converts singlet excitation energy into light emission>> Examples of luminescent materials that can be used in the light-emitting layers (113, 113a, 113b) to convert singlet excitation energy into light include the following fluorescent materials (fluorescent materials). For example, pyrene derivatives, anthracene derivatives, triphenylene derivatives, fluorene derivatives, carbazole derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, dibenzoquinoxaline derivatives, quinoxaline derivatives, pyridine derivatives, pyrimidine derivatives, phenanthrene derivatives, and naphthalene derivatives are examples. Pyrene derivatives are particularly preferred because they have a high luminescence quantum yield. Specific examples of pyrene derivatives include N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-bis(dibenzofuran-2-yl)-N,N'-diphenylpyrene-1,6-diamine (abbreviation: 1,6FrAPrn), N,N'-bis(dibenzothiophen-2-yl)-N, Examples include N'-diphenylpyrene-1,6-diamine (abbreviation: 1,6ThAPrn), N,N'-(pyrene-1,6-diyl)bis[(N-phenylbenzo[b]naphtho[1,2-d]furan)-6-amine] (abbreviation: 1,6BnfAPrn), N,N'-(pyrene-1,6-diyl)bis[(N-phenylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-02), and N,N'-(pyrene-1,6-diyl)bis[(6,N-diphenylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-03).

[0194] Also, 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'-bis[4-(9H-carbazole-9-yl)phenyl]-N,N'-diphenyl-4,4'-stilbendiamine (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), 4-(10-phenyl-9-anthryl)-4'- (9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBAPA), 4-[4-(10-phenyl-9-antryl)phenyl]-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBAPBA), perylene, 2,5,8,11-tetra-tert-butylperylene (abbreviation: TBP), N,N''-(2-tert-butylanthracene-9,10-diyldi-4,1-phenyl) Nilen)bis(N,N',N'-triphenyl-1,4-phenylenediamine) (abbreviated as DPABPA), N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazole-3-amine (abbreviated as 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviated as 2DPAPPA), etc. can be used.

[0195] Also, N,N,N',N',N'',N'',N''',N'''-Octaphenyldibenzo[g,p]chrysen-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(biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazole-3-amine (abbreviation: 2PCABPhA), N-(9,10-diphenyl-2-anthryl)-N,N',N'-Trif Phenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-bis(biphenyl-2-yl)-2-anthryl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPABPhA), 9,10-bis(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: DP) Qd), rubren, 5,12-bis(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-diamine (abbreviation: p-mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinoridine-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7-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 Examples include propanedinitrile (abbreviation: BisDCJTM), 1,6BnfAPrn-03, N,N'-diphenyl-N,N'-bis(9-phenyl-9H-carbazole-2-yl)naphtho[2,3-b;6,7-b']bisbenzofuran-3,10-diamine (abbreviation: 3,10PCA2Nbf(IV)-02), and N,N'-bis(dibenzofuran-3-yl)-N,N'-diphenylnaphtho[2,3-b;6,7-b']bisbenzofuran-3,10-diamine (abbreviation: 3,10FrA2Nbf(IV)-02). In particular, pyrenediamine compounds such as 1,6FLPAPrn, 1,6mMemFLPAPrn, and 1,6BnfAPrn-03 can be used.

[0196] Also, 5,9-diphenyl-5H,9H-[1,4]benzazabolino[2,3,4-kl]phenazabolin (abbreviated as DABNA-1), 9-(biphenyl-3-yl)-N,N,5,11-tetraphenyl-5H,9H-[1,4]benzazabolino[2,3,4-kl]phenazabolin-3-amine (abbreviated as DABNA-2), 2,12-di(tert-butyl)-5,9-di(4-tert-butylphenyl)-N,N-di Phenyl-5H,9H-[1,4]benzazabolino[2,3,4-kl]phenazabolin-7-amine (abbreviation: DPhA-tBu4DABNA), 2,12-di(tert-butyl)-N,N,5,9-tetra(4-tert-butylphenyl)-5H,9H-[1,4]benzazabolino[2,3,4-kl]phenazabolin-7-amine (abbreviation: tBuDPhA-tBu4DABNA), 2,12-di(tert-butyl)- 5,9-di(4-tert-butylphenyl)-7-methyl-5H,9H-[1,4]benzazabolino[2,3,4-kl]phenazabolin (abbreviation: Me-tBu4DABNA), N7,N7,N13,N13,5,9,11,15-octaphenyl-5H,9H,11H,15H-[1,4]benzazabolino[2,3,4-kl][1,4]benzazabolino[4',3',2':4,5][1,4]benzazabolino[3, Condensed heteroaromatic compounds containing nitrogen and boron, such as 2-b]phenazavolin-7,13-diamine (abbreviated as ν-DABNA) and 2-(4-tert-butylphenyl)benz[5,6]indro[3,2,1-jk]benzo[b]carbazole (abbreviated as tBuPBibc), particularly compounds having a diaza-boranaphtho-anthracene skeleton, can be suitably used because they produce blue emission with a narrow emission spectrum and good color purity.

[0197] In addition to these, compounds having an indole skeleton such as 9,10,11-tris[3,6-bis(1,1-dimethylethyl)-9H-carbazolyl-9-yl]-2,5,15,18-tetrakis(1,1-dimethylethyl)indolo[3,2,1-de]indolo[3’,2’,1’:8,1][1,4]benzazaborino[2,3,4-kl]phenazaborine (abbreviation: BBCz-G), 9,11-bis[3,6-bis(1,1-dimethylethyl)-9H-carbazolyl-9-yl]-2,5,15,18-tetrakis(1,1-dimethylethyl)indolo[3,2,1-de]indolo[3’,2’,1’:8,1][1,4]benzazaborino[2,3,4-kl]phenazaborine (abbreviation: BBCz-Y) can be preferably used.

[0198] ≪Luminescent Substance Converting Triplet Excitation Energy into Luminescence≫ Next, examples of the luminescent substance that can convert triplet excitation energy into luminescence and can be used in the light-emitting layer 113 include substances that emit phosphorescence (phosphorescent substances) or thermally activated delayed fluorescence (Thermally Activated Delayed Fluorescence: TADF) materials that exhibit thermally activated delayed fluorescence.

[0199] A phosphorescent substance refers to a compound that exhibits phosphorescence and does not exhibit fluorescence in any temperature range from low temperature (e.g., 7 K) to room temperature or below (i.e., from 77 K to 313 K). The phosphorescent substance preferably has a metal element with a large spin-orbit interaction, and examples include organometallic complexes, metal complexes (platinum complexes), and rare earth metal complexes. Specifically, transition metal elements are preferred, and in particular, it is preferable to have a platinum group element (ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), or platinum (Pt)). Among them, having iridium can increase the transition probability related to the direct transition between the singlet ground state and the triplet excited state, which is preferable.

[0200] ≪Phosphorescent Substance (Wavelength: 400 nm or more and less than 580 nm: Blue or Green)≫ Examples of the phosphorescent substance that exhibits blue or green and has a peak wavelength of the emission spectrum of 400 nm or more and less than 580 nm include the following substances.

[0201] For example, tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN2]phenyl-κC}iridium(III) (abbreviation: [Ir(mpptz-dmp)3]), tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Mptz)3]), tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(iPrptz-3b)3]), tris[3-(5-biphenyl)-5-isopropyl-4-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(iPr5btz)3]), and other organometallic complexes having a 4H-triazole ring, tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(Mptz1-mp)3]), tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Prptz1-Me)3]) and other organometallic complexes having a 1H-triazole ring, fac-tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviation: [Ir(iPrpim)3]), tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: [Ir(dmpimpt-Me)3]), tris(2-{1-[2,6-bis(1-methylethyl)phenyl]-1H-imidazole-2-yl-κN 3}-4-cyanophenyl-κC)iridium(III) (abbreviation: CNImIr) and other organometallic complexes having an imidazole ring, tris[(6-tert-butyl-3-phenyl-2H-imidazo[4,5-b]pyrazin-1-yl-κC 2Organometallic complexes having a benzimidazolidene skeleton, such as )phenyl-κC]iridium(III) (abbreviation: [Ir(cb)3]), bis[2-(4',6'-difluorophenyl)pyridinate-N,C 2’ Iridium(III) tetrakis(1-pyrazolyl) borate (abbreviation: FIr6), bis[2-(4',6'-difluorophenyl)pyridinate-N,C 2’ Iridium(III) 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’ Organometallic complexes with phenylpyridine derivatives having electron-withdrawing groups as ligands, such as iridium(III) acetylacetonate (abbreviation: Fir(acac)), (2-{3-[3-(3,5-di-tert-butylphenyl)benzimidazole-1-yl-2-ylidene-κC 2 ] Phenoxy-κC 2}-9-(4-tert-butyl-2-pyridinyl-κN)carbazole-2,1-diyl-κC 1 Examples include platinum(II) complexes such as PtON-TBBI. Compounds in which some of the hydrogen atoms in these compounds are replaced with deuterium can also be used.

[0202] ≪Phosphorescent materials (wavelengths between 490nm and 590nm: green or yellow)≫ Examples of phosphorescent materials that exhibit a green or yellow color and have a peak wavelength of emission spectrum between 490 nm and 590 nm include the following:

[0203] For example, tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)3]), tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)3]), (acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)2(acac)]), (acetylacetonato)bis(6-tert- (Ir(tBuppm)2(acac)), (acetylacetonato)bis[6-(2-norbornyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(nbppm)2(acac)]), (acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(mpmppm Organometallic iridium(III) having a pyrimidine ring, such as (acetylacetonato)bis{4,6-dimethyl-2-[6-(2,6-dimethylphenyl)-4-pyrimidinyl-κN3]phenyl-κC}iridium(III) (abbreviation: [Ir(dmppm-dmp)2(acac)]), (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm)2(acac)]), iridium complexes having a pyrazine ring, 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-phenylpyridinato-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’Iridium(III) acetylacetonate (abbreviation: [Ir(pq)2(acac)]), bis[2-(2-pyridinyl-κN)phenyl-κC][2-(4-phenyl-2-pyridinyl-κN)phenyl-κC] Iridium(III) (abbreviation: [Ir(ppy)2(4dppy)]), bis[2-(2-pyridinyl-κN)phenyl-κC][2-(4-methyl-5-phenyl-2-pyridinyl-κN)phenyl-κC], [2-d3-methyl-8-(2-pyridinyl-κN)benzofl[2,3-b]pyridine-κC] bis[2-(5-d3-methyl [2-pyridinyl-κN2)phenyl-κC]iridium(III) (abbreviation: Ir(5mppy-d3)2(mbfpypy-d3)), {2-(methyl-d3)-8-[4-(1-methylethyl-1-d)-2-pyridinyl-κN]benzofl[2,3-b]pyridin-7-yl-κC}bis{5-(methyl-d3)-2-[5-(methyl-d3)-2-pyridinyl-κN]phenyl-κC}iridium(III) (abbreviation: Ir(5mppy-d6)2(mbfpypy-iPr-d4)), [2-(methyl-d3)-8-(2-pyridinyl-κN)ben [zoflo[2,3-b]pyridine-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: Ir(ppy)2(mbfpypy-d3)), [2-(4-methyl-5-phenyl-2-pyridinyl-κN)phenyl-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: Ir(ppy)2(mdppy)), [2-(4-d3-methyl-5-phenyl-2-pyridinyl-κN2)phenyl-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN2)phenyl-κC]iridium iridium organometallic complexes having a pyridine ring, such as Iridium(III) (abbreviation: [Ir(5mppy-d3)2(mdppy-d3)]), [2-methyl-8-(2-pyridinyl-κN)benzofloflo[2,3-b]pyridine-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: Ir(ppy)2(mbfpypy)), and Tris{2-[5-(methyl-d3)-4-phenyl-2-pyridinyl-κN]phenyl-κC}iridium(III) (abbreviation: Ir(5m4dppy-d3)3), bis(2,4-diphenyl-1,3-Oxazolato-N,C, 2’ Iridium(III) acetylacetonate (abbreviation: [Ir(dpo)2(acac)]), bis{2-[4'-(perfluorophenyl)phenyl]pyridinate-N,C 2’ Iridium(III) acetylacetonate (abbreviation: [Ir(p-PF-ph)2(acac)]), bis(2-phenylbenzothiazolat-N,C) 2’ In addition to organometallic complexes such as iridium(III) acetylacetonate (abbreviation: [Ir(bt)2(acac)]), rare earth metal complexes such as tris(acetylacetonate)(monophenanthroline)terbium(III) (abbreviation: [Tb(acac)3(Phen)]), and (2-{1-(5-tert-butylbiphenyl-2-yl)-4-[3-tert-butyl-5-(4-phenyl-2-pyridinyl-κN)phenyl-κC6]-2-benzimidazolyl-κN3}-4,6-di-t Examples of organometallic platinum complexes include ert-butylphenolate-κO)platinum(II) (abbreviation: Pt(tBudppymmtBubiz-tBubp)) and [2-(4-(3,5-di-tert-butylphenyl)-6-{3-[4-(5'-tert-butyl[1,1':3',1''-terphenyl]-2'-yl)-2-pyridinyl-κN]phenyl-κC2}-2-pyridinyl-κN)phenolate-κO]platinum(II) (abbreviation: Pt(4tButpppypyp-mmtBup)). Compounds in which some of the hydrogen atoms in these compounds are replaced with deuterium can also be used.

[0204] ≪Phosphorescent materials (wavelengths between 570nm and 750nm: yellow or red)≫ Examples of phosphorescent materials that exhibit a yellow or red color and have a peak wavelength of emission spectrum between 570 nm and 750 nm include the following:

[0205] For example, (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III) (abbreviation: [Ir(5mdppm)2(dibm)]), bis[4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(5mdppm)2(dpm)]), (dipivaloylmethanato)bis[4,6-di(naphthalene-1-yl)pyrimidinato]iridium(III) (abbreviation: [Ir(d1npm)2(dpm)]), and other pyramidal compounds. Organometallic complexes having a limidine ring: (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)]), bis{4,6-dimethyl-2-[3-(3,5-dimethylphenyl)-5-phenyl-2-pyrazinyl-κN]phenyl-κC}(2,6-dimethyl-3,5-heptanedionato-κ 2 O,O') Iridium(III) (abbreviation: [Ir(dmdppr-P)2(dibm)]), bis{4,6-dimethyl-2-[5-(4-cyano-2,6-dimethylphenyl)-3-(3,5-dimethylphenyl)-2-pyradinyl-κN]phenyl-κC}(2,2,6,6-tetramethyl-3,5-heptanedionato-κ 2 O,O') Iridium(III) (abbreviation: [Ir(dmdppr-dmCP)2(dpm)]), bis{2-[5-(2,6-dimethylphenyl)-3-(3,5-dimethylphenyl)-2-pyrazinyl-κN]-4,6-dimethylphenyl-κC}(2,2',6,6'-tetramethyl-3,5-heptanedionato-κ 2 O,O') Iridium(III) (abbreviation: [Ir(dmdppr-dmp)2(dpm)]), (acetylacetonato)bis(2-methyl-3-phenylquinoxalinato-N,C 2’ Iridium(III) (abbreviation: [Ir(mpq)2(acac)]), (acetylacetonato)bis(2,3-diphenylquinoxalinato-N,C) 2’Organometallic complexes having a pyrazine ring, such as iridium(III) (abbreviation: [Ir(dpq)2(acac)]), (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’ Iridium(III) acetylacetonate (abbreviation: [Ir(piq)2(acac)]), and bis[4,6-dimethyl-2-(2-quinolinyl-κN)phenyl-κC](2,4-pentanedionato-κ 2 Organometallic complexes having a pyridine ring, such as O,O') Iridium(III) (abbreviation: [Ir(dmpqn)2(acac)]), (3,7-diethyl-4,6-nonanedionato-κO4,κO6)bis[2,4-dimethyl-6-[7-(1-methylethyl)-1-isoquinolinyl-κN]phenyl-κC] Iridium(III), and (3,7-diethyl-4,6-nonanedionato-κO4,κO6)bis[2,4-dimethyl-6-[5-(1-methylethyl)-2-quinolinyl-κN]phenyl-κC] Iridium(III). Examples include platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum(II) (abbreviated as [PtOEP]), 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)]). Compounds in which some of the hydrogen atoms in these compounds are replaced with deuterium can also be used.

[0206] ≪TADF material≫ Furthermore, the following materials can be used as TADF materials. A TADF material is a material in which the energy difference between the S1 level and the T1 level is small (preferably 0.20 eV or less), the triplet excited state can be upconverted to the singlet excited state with a small amount of thermal energy (reverse intersystem crossing), and the emission (fluorescence) from the singlet excited state is efficiently observed. Conditions for efficiently obtaining thermally activated delayed fluorescence include an energy difference between the triplet excited energy level and the singlet excited energy level of 0.00 eV or more and 0.20 eV or less, preferably 0.00 eV or more and 0.10 eV or less. In addition, delayed fluorescence in TADF materials refers to emission that has a spectrum similar to normal fluorescence but with a remarkably long lifetime. Its lifetime is 1 × 10⁻⁶ -6 More than a second, or 1 x 10⁻⁶ -3 It is more than a second.

[0207] Furthermore, TADF materials can also be used as electron transport materials, hole transport materials, and host materials.

[0208] Examples of TADF materials include fullerenes and their derivatives, acridine derivatives such as proflavin, and eosin. Also, metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd) are also used. Examples of metal-containing porphyrins include protoporphyrin-tin fluoride complexes (abbreviated as SnF2(Proto IX)), mesoporphyrin-tin fluoride complexes (abbreviated as SnF2(Meso IX)), hematoporphyrin-tin fluoride complexes (abbreviated as SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complexes (abbreviated as SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complexes (abbreviated as SnF2(OEP)), etioporphyrin-tin fluoride complexes (abbreviated as SnF2(Etio I)), and octaethylporphyrin-platinum chloride complexes (abbreviated as PtCl2OEP).

[0209] [ka]

[0210] Other examples include 2-(biphenyl-4-yl)-4,6-bis(12-phenylindoro[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviated as PIC-TRZ), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviated as PCCzPTzn), and 2-[4-(10H-phenoxa [Zin-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: PXZ-TRZ), 3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridine-10-yl)-9H-xanthene-9-one (abbreviation: ACRXTN), bis[4-(9,9- Dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), 10-phenyl-10H,10'H-spiro[acridine-9,9'-anthracene]-10'-one (abbreviation: ACRSA), 4-(9'-phenyl-[3,3'-bi-9H-carbazole]-9-yl)benzofloflo[3,2-d]pyrimidine (abbreviation: 4PCCzBfpm), 4-[4-(9'-phenyl-[3,3'- You may also use heteroaromatic compounds that have π-electron-rich heteroaromatic compounds and π-electron-deficient heteroaromatic compounds such as bi-9H-carbazole]-9-yl)phenyl]benzofl[3,2-d]pyrimidine (abbreviation: 4PCCzPBfpm) and 9-[3-(4,6-diphenyl-1,3,5-triazine-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02).

[0211] Furthermore, a material in which a π-electron-rich heteroaromatic compound and a π-electron-deficient heteroaromatic compound are directly bonded is particularly preferable because both the donor properties of the π-electron-rich heteroaromatic compound and the acceptor properties of the π-electron-deficient heteroaromatic compound become stronger, and the energy difference between the singlet excited state and the triplet excited state becomes smaller. In addition, a TADF material (TADF100) in which the singlet excited state and the triplet excited state are in thermal equilibrium may be used as the TADF material. 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 device.

[0212] [ka]

[0213] In addition to the above, other materials that have the function of converting triplet excitation energy into light emission include nanostructures of transition metal compounds having a perovskite structure. Nanostructures of metal halogen perovskites are particularly desirable. Nanoparticles and nanorods are preferred as such nanostructures.

[0214] The light-emitting layer 113 can also be composed of two or more layers. For example, when the light-emitting layer 113 is formed by stacking a first light-emitting layer and a second light-emitting layer in order from the hole transport layer side, a material with hole transport properties can be used as the host material for the first light-emitting layer, and a material with electron transport properties can be used as the host material for the second light-emitting layer. Furthermore, the light-emitting materials of the first light-emitting layer and the second light-emitting layer may be the same material or different materials, and they may be materials that exhibit the same color of light emission or materials that exhibit different colors of light emission. By using light-emitting materials that exhibit different colors of light emission for each of the two light-emitting layers, multiple light emission can be obtained simultaneously. In particular, it is preferable to select the light-emitting materials used for each light-emitting layer so that the light emitted by the two light-emitting layers results in white light.

[0215] Furthermore, the light-emitting layer 113 may contain materials other than the host material 118 and the guest material 119.

[0216] Note that the light-emitting layer 113 can be formed by methods such as vapor deposition (including vacuum vapor deposition), inkjet method, coating method, gravure printing, etc. Further, in addition to the materials described above, it may have inorganic compounds such as quantum dots or polymer compounds (oligomers, dendrimers, polymers, etc.).

[0217] ≪Hole injection layer≫ The hole injection layers (111, 111a, 111b) are layers that inject holes into the organic compound layers (103, 103a, 103b) from the first electrode 101 that functions as an anode and the charge generation layers (106, 106a, 106b), and are layers containing an organic acceptor material and a material with high hole injection properties.

[0218] The hole injection layers (111, 111a, 111b) have a function of promoting hole injection by reducing the hole injection barrier from one of the pair of electrodes (the first electrode 101 or the second electrode 102), and are formed by, for example, transition metal oxides, phthalocyanine derivatives, or aromatic amines. Examples of transition metal oxides include molybdenum oxides, vanadium oxides, ruthenium oxides, tungsten oxides, manganese oxides, etc. Examples of phthalocyanine derivatives include phthalocyanine or metal phthalocyanine. Examples of aromatic amines include benzidine derivatives or phenylenediamine derivatives. Polymer compounds such as polythiophene or polyaniline can also be used, and for example, poly(ethylenedioxythiophene) / polystyrene sulfonic acid, which is self-doped polythiophene, is a representative example thereof.

[0219] As the hole injection layer (111, 111a, 111b), a layer having a composite material of a hole-transporting material and a material exhibiting electron-accepting properties to it can also be used. Alternatively, a laminate of a layer containing an electron-accepting material and a layer containing a hole-transporting material may be used. Charge transfer is possible between these materials in a steady state or in the presence of an electric field. Examples of electron-accepting materials include organic acceptors such as quinodimethane derivatives, chloranil derivatives, or hexaazatriphenylene derivatives. Specifically, these are compounds having electron-withdrawing groups (halogen groups or cyano groups) such as 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviated as F4-TCNQ), chloranil, and 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviated as HAT-CN). Furthermore, transition metal oxides, such as oxides of Group 4 to Group 8 metals, can be used. Specifically, these include vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, and rhenium oxide. Among these, molybdenum oxide is preferred because it is stable in the atmosphere, has low hygroscopicity, and is easy to handle.

[0220] As a hole-transporting material, a material with higher hole transport capabilities than electron transport can be used, resulting in a capacity of 1 × 10⁻⁶. -6 cm 2 It is preferable that the material has a hole mobility of / Vs or greater. Specifically, aromatic amines, carbazole derivatives, aromatic hydrocarbons, stilbene derivatives, etc., listed as hole transport materials that can be used in the light-emitting layer 113 can be used. Furthermore, the hole transport material may also be a polymer compound.

[0221] ≪Hole transport layer≫ The hole transport layer (112, 112a, 112b) is a layer containing a hole transport material, and the hole transport materials exemplified as the materials of the hole injection layer (111, 111a, 111b) can be used. Since the hole transport layer (112, 112a, 112b) has the function of transporting the holes injected into the hole injection layer (111, 111a, 111b) to the light-emitting layer (113, 113a, 113b), it preferably has a HOMO level that is the same as or close to the HOMO level of the hole injection layer (111, 111a, 111b).

[0222] In addition, the above hole transport material is preferably a substance having a hole mobility of 1×10 -6 cm 2 / Vs or more. However, as long as the substance has higher hole transportability than electrons, other substances may be used. Note that the layer containing a substance with high hole transportability may be not only a single layer, but also two or more layers of the layers made of the above substances laminated.

[0223] <<Electron Transport Layer>> The electron transport layer (114, 114a, 114b) has the function of transporting the electrons injected from the other of the pair of electrodes (the first electrode 101 or the second electrode 102) through the electron injection layer (115, 115a, 115b) to the light-emitting layer 113. As the electron transport material, a material having higher electron transportability than holes can be used, and it is preferably a material having an electron mobility of 1×10 -6 cm 2 / Vs or more. As the compound (material having electron transportability) that is easy to receive electrons, a compound having a π-electron-deficient heteroaromatic ring skeleton such as a nitrogen-containing heteroaromatic compound, or a metal complex can be used. Specifically, metal complexes having quinoline ligands, benzoquinoline ligands, oxazole ligands, or thiazole ligands, which were exemplified as the electron transport materials that can be used for the light-emitting layer 113, can be mentioned. In addition, oxadiazole derivatives, triazole derivatives, benzimidazole derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, phenanthroline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, triazine derivatives, etc. can be mentioned. In addition, the above electron transport material is 1×10-6 cm 2 It is preferable that the material has an electron mobility of / Vs or higher. However, any material other than the above may be used as the electron transport layer as long as it has higher electron transport capabilities than hole transport. Furthermore, the electron transport layer (114, 114a, 114b) may be a single layer or two or more layers made of the above material stacked together.

[0224] Furthermore, a layer for controlling the movement of electron carriers may be provided between the electron transport layers (114, 114a, 114b) and the light-emitting layers (113, 113a, 113b). This layer is made by adding a small amount of a substance with high electron-trapping properties to the electron-transporting material described above, and by suppressing the movement of electron carriers, it is possible to adjust the carrier balance. Such a configuration is highly effective in suppressing problems that occur when electrons penetrate the light-emitting layer (for example, a decrease in device lifetime).

[0225] ≪Electron injection layer≫ The electron injection layers (115, 115a, 115b) have the function of promoting electron injection by reducing the electron injection barrier from the second electrode 102, and can be made of, for example, Group 1 metals, Group 2 metals, or their oxides, halides, carbonates, etc. Alternatively, composite materials of the electron-transporting material and an electron-donating material can be used. Examples of electron-donating materials include Group 1 metals, Group 2 metals, or their oxides. Specifically, lithium fluoride (LiF), sodium fluoride (NaF), cesium fluoride (CsF), calcium fluoride (CaF2), lithium oxide (LiO2) xAlkali metals, alkaline earth metals, or compounds thereof can be used. Rare earth metal compounds such as erbium fluoride (ErF3) can also be used. An electride may also be used in the electron injection layer 115. Examples of such electrides include a substance obtained by adding electrons to a mixed oxide of calcium and aluminum at a high concentration. In addition, the electron injection layers (115, 115a, 115b) may be made of materials that can be used in the electron transport layers (114, 114a, 114b).

[0226] Furthermore, a composite material obtained by mixing an organic compound and an electron donor may be used in the electron injection layers (115, 115a, 115b). Such a composite material exhibits excellent electron injection and electron transport properties because electrons are generated in the organic compound by the electron donor. In this case, the organic compound is preferably a material with excellent electron transport properties, and specifically, for example, a substance (metal complex or heteroaromatic compound, etc.) that constitutes the electron transport layer 114 of the above-described sequential-stack type light-emitting device can be used. The electron donor can be any substance that exhibits electron-donating properties to the organic compound. Specifically, alkali metals, alkaline earth metals, or rare earth metals are preferred, such as lithium, sodium, cesium, magnesium, calcium, erbium, and ytterbium. Alkali metal oxides or alkaline earth metal oxides are also preferred, such as lithium oxide, calcium oxide, and barium oxide. Lewis bases such as magnesium oxide can also be used. Furthermore, organic compounds such as tetrathiafulvalene (abbreviated as TTF) can also be used.

[0227] Furthermore, a strongly basic material may be used for the electron injection layers (115, 115a, 115b). Specifically, organic compounds such as 1-(9,9'-spirobi[9H-fluoren]-2-yl)-1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine (abbreviated as 2hppSF), 2,9-bis(1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine-1-yl)-1,10-phenanthroline (abbreviated as 2,9hpp2Phen), 4,7-di-1-pyrrolidinyl-1,10-phenanthroline (abbreviated as Pyrrd-Phen), or 8,8'-pyridine-2,6-diyl-bis(5,6,7,8-tetrahydroimidazo[1,2-a]pyrimidine) (abbreviated as 2,6tip2Py) can be used as materials having strong basicity.

[0228] Furthermore, the light-emitting layer described above is preferably formed by vapor deposition (including vacuum deposition). The hole injection layer, hole transport layer, electron transport layer, and electron injection layer can each be formed by vapor deposition (including vacuum deposition), inkjet, coating, gravure printing, or other methods. In addition to the materials described above, inorganic compounds such as quantum dots or polymer compounds (oligomers, dendrimers, polymers, etc.) may also be used for the light-emitting layer, hole injection layer, hole transport layer, electron transport layer, and electron injection layer.

[0229] Furthermore, the quantum dots may include colloidal quantum dots, alloy quantum dots, core-shell quantum dots, core quantum dots, etc. Quantum dots containing elemental groups from groups 2 and 16, 13 and 15, 13 and 17, 11 and 17, or 14 and 15 may also be used. Alternatively, quantum dots containing elements such as cadmium (Cd), selenium (Se), zinc (Zn), sulfur (S), phosphorus (P), indium (In), tellurium (Te), lead (Pb), gallium (Ga), arsenic (As), and aluminum (Al) may be used.

[0230] ≪A pair of electrodes≫ The first electrode 101 and the second electrode 102 function as the anode or cathode of the light-emitting device. The first electrode 101 and the second electrode 102 can be formed using metals, alloys, conductive compounds, mixtures thereof, or laminates.

[0231] Preferably, one of the first electrode 101 or the second electrode 102 is formed of a conductive material having the function of reflecting light. Examples of such conductive materials include aluminum (Al) or alloys containing Al. Examples of alloys containing Al include alloys containing Al and L (where L represents one or more of titanium (Ti), neodymium (Nd), nickel (Ni), and lanthanum (La)), such as alloys containing Al and Ti, or Al, Ni, and La. Aluminum has low resistance and high light reflectivity. In addition, since aluminum is abundant in the Earth's crust and inexpensive, the cost of manufacturing the light-emitting device can be reduced by using aluminum. In addition, alloys containing silver (Ag), or Ag and N (where N represents one or more of yttrium (Y), Nd, magnesium (Mg), ytterbium (Yb), Al, Ti, gallium (Ga), zinc (Zn), indium (In), tungsten (W), manganese (Mn), tin (Sn), iron (Fe), Ni, copper (Cu), palladium (Pd), iridium (Ir), or gold (Au) may be used. Examples of silver-containing alloys include alloys containing silver, palladium, and copper; alloys containing silver and copper; alloys containing silver and magnesium; alloys containing silver and nickel; alloys containing silver and gold; and alloys containing silver and ytterbium. Other transition metals such as tungsten, chromium (Cr), molybdenum (Mo), copper, and titanium can also be used.

[0232] Furthermore, the light emitted from the light-emitting layer is extracted through one or both of the first electrode 101 and the second electrode 102. Therefore, it is preferable that at least one of the first electrode 101 and the second electrode 102 be made of a conductive material that has the function of transmitting light. The conductive material has a visible light transmittance of 40% to 100%, preferably 60% to 100%, and a resistivity of 1 × 10⁻⁶. -2 Examples include conductive materials with a conductivity of Ω·cm or less.

[0233] Furthermore, the first electrode 101 and the second electrode 102 may be formed from a conductive material having both a light-transmitting function and a light-reflecting function. The conductive material has a visible light reflectance of 20% to 80%, preferably 40% to 70%, and a resistivity of 1 × 10⁻⁶. -2 Examples of conductive materials include those with a conductivity of Ω·cm or less. For example, they can be formed using one or more types of conductive metals, alloys, or conductive compounds. Specifically, metal oxides such as indium tin oxide (ITO), indium tin oxide containing silicon or silicon oxide (ITSO), indium zinc oxide, indium tin oxide containing titanium, indium titanium oxide, and indium oxide containing tungsten oxide and zinc oxide can be used. In addition, thin metal films that transmit light (preferably with a thickness of 1 nm to 30 nm) can be used. As metals, for example, Ag, or alloys such as Ag and Al, Ag and Mg, Ag and Au, Ag and Yb can be used.

[0234] In addition, in this specification and the like, the material having the function of transmitting light may be any material that has the function of transmitting visible light and has conductivity. For example, in addition to the oxide conductor represented by ITO as described above, it includes oxide semiconductors or organic conductors containing organic substances. Examples of the organic conductor containing an organic substance include a composite material formed by mixing an organic compound and an electron donor (donor), a composite material formed by mixing an organic compound and an electron acceptor (acceptor), and the like. Also, an inorganic carbon-based material such as graphene may be used. Further, the resistivity of the material is preferably 1×10 5 Ω·cm or less, more preferably 1×10 4 Ω·cm or less.

[0235] Also, one or both of the first electrode 101 and the second electrode 102 may be formed by laminating a plurality of the above materials.

[0236] In addition, in order to improve the light extraction efficiency, a material having a higher refractive index than the electrode may be formed in contact with the electrode having the function of transmitting light. Such a material may be any material that has the function of transmitting visible light, and may or may not have conductivity. For example, in addition to the oxide conductor as described above, oxide semiconductors and organic substances are included. Examples of the organic substance include the materials exemplified for the light-emitting layer, hole injection layer, hole transport layer, electron transport layer, or electron injection layer. Also, an inorganic carbon-based material or a metal thin film through which light can pass may be used, and a plurality of layers with a film thickness of several nm to several tens of nm may be laminated.

[0237] When the first electrode 101 or the second electrode 102 has the function as a cathode, it preferably has a material with a small work function (3.8 eV or less). For example, elements belonging to Group 1 or Group 2 of the periodic table (alkali metals such as lithium, sodium, cesium, alkaline earth metals such as calcium, strontium, magnesium, etc.), alloys containing these elements (e.g., Ag and Mg, Al and Li), rare earth metals such as europium (Eu), Yb, alloys containing these rare earth metals, aluminum, alloys containing silver, etc. can be used.

[0238] Furthermore, when using the first electrode 101 or the second electrode 102 as an anode, it is preferable to use a material with a large work function (4.0 eV or more).

[0239] Furthermore, the first electrode 101 and the second electrode 102 may be laminates of a conductive material having the function of reflecting light and a conductive material having the function of transmitting light. In that case, the first electrode 101 and the second electrode 102 are preferable because they can have a function to adjust the optical distance so that the light from each light-emitting layer resonates at a desired wavelength and the light of that wavelength is intensified.

[0240] The first electrode 101 and the second electrode 102 can be formed using methods such as sputtering, vapor deposition, printing, coating, MBE (Molecular Beam Epitaxy), CVD (Chemical Vapor Deposition), pulsed laser deposition, or atomic layer deposition (ALD), as appropriate.

[0241] ≪Charge Generation Layer≫ The charge generation layer 106 has the function of injecting electrons into the organic compound layer 103a and holes into the organic compound layer 103b when a voltage is applied between the first electrode (anode) 101 and the second electrode (cathode) 102. The charge generation layer 106 may be configured in which an electron acceptor is added to a hole transport material (also called a P-type layer), or in which an electron donor is added to an electron transport material (also called an electron injection buffer layer). Furthermore, both of these configurations may be laminated. In addition, an electron relay layer may be provided between the P-type layer and the electron injection buffer layer. By forming the charge generation layer 106 using the materials described above, it is possible to suppress the increase in driving voltage when the organic compound layers are laminated.

[0242] In the charge generation layer 106, when an electron acceptor is added to a hole-transporting material which is an organic compound (P-type layer), the material shown in this embodiment can be used as the hole-transporting material. Examples of electron acceptors include 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviated as F4-TCNQ), chloranil, etc. Other examples include oxides of metals belonging to groups 4 to 8 of the periodic table. Specifically, examples include vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, and rhenium oxide. The acceptor material described above may also be used. Furthermore, the P-type layer may be used as a mixed film by mixing the materials, or as single films containing each material stacked together.

[0243] Furthermore, in the charge generation layer 106, if an electron donor is added to the electron transport material (electron injection buffer layer), the materials shown in this embodiment can be used as the electron transport material. As the electron donor, alkali metals, alkaline earth metals, rare earth metals, or metals belonging to groups 2 and 13 of the periodic table, as well as their oxides and carbonates, can be used. Specifically, lithium (Li), cesium (Cs), magnesium (Mg), calcium (Ca), ytterbium (Yb), indium (In), lithium oxide (Li2O), cesium carbonate, etc., are preferred. Organic compounds such as tetrathianaphthalene may also be used as electron donors.

[0244] In the charge generation layer 106, when an electron relay layer is provided between the P-type layer and the electron injection buffer layer, the electron relay layer contains at least an electron-transporting material and has the function of preventing interaction between the electron injection buffer layer and the P-type layer and smoothly transferring electrons. Preferably, the LUMO level of the electron-transporting material included in the electron relay layer is between the LUMO level of the acceptor material in the P-type layer and the LUMO level of the electron-transporting material included in the electron transport layer in contact with the charge generation layer 106. The specific energy level of the LUMO level of the electron-transporting material used in the electron relay layer is preferably -5.0 eV or higher, more preferably -5.0 eV or higher and -3.0 eV or lower. Preferably, as the electron-transporting material used in the electron relay layer, a phthalocyanine-based material or a metal complex having a metal-oxygen bond and an aromatic ligand is used.

[0245] Although Figure 6(D) shows a configuration in which two organic compound layers 103 are stacked, a stacked structure of three or more organic compound layers may be used by providing a charge generation layer between different organic compound layers.

[0246] ≪Capping layer≫ Although not shown in Figures 6(A) to 6(E), a cap layer may be provided on the second electrode 102 of the light-emitting device. For example, a material with a high refractive index can be used for the cap layer. By providing a cap layer on the second electrode 102, the extraction efficiency of the light emitted from the second electrode 102 can be improved.

[0247] Specific examples of materials that can be used for the cap layer include 5,5'-diphenyl-2,2'-di-5H-[1]benzothieno[3,2-c]carbazole (abbreviated as BisBTc) and 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviated as DBT3P-II).

[0248] Circuit board Furthermore, a light-emitting device according to one aspect of the present invention may be fabricated on a substrate made of glass, plastic, or the like. The order in which the components are fabricated on the substrate may be either by stacking them sequentially from the first electrode 101 side, or by stacking them sequentially from the second electrode 102 side.

[0249] Furthermore, as a substrate on which a light-emitting device according to one aspect of the present invention can be formed, for example, glass, quartz, or plastic can be used. A flexible substrate may also be used. A flexible substrate is a substrate that can be bent (flexible), and examples include plastic substrates made of polycarbonate or polyarylate. Films, inorganic vapor-deposited films, etc., can also be used. However, other materials are also acceptable as long as they function as a support in the manufacturing process of the light-emitting device and optical element. Alternatively, any material that has the function of protecting the light-emitting device and optical element is acceptable.

[0250] For example, in this specification, light-emitting devices can be formed using various substrates. The type of substrate is not particularly limited. Examples of substrates include semiconductor substrates (e.g., single crystal substrates or silicon substrates), SOI substrates, glass substrates, quartz substrates, plastic substrates, metal substrates, stainless steel substrates, substrates with stainless steel foil, tungsten substrates, substrates with tungsten foil, flexible substrates, laminated films, cellulose nanofibers (CNF) containing fibrous materials, paper, or base films. Examples of glass substrates include barium borosilicate glass, aluminobosilicate glass, or soda-lime glass. Examples of flexible substrates, laminated films, and base films include the following: For example, plastics such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), and polytetrafluoroethylene (PTFE). Alternatively, as an example, acrylic resin. Alternatively, as an example, polypropylene, polyester, polyvinyl fluoride, or polyvinyl chloride. Alternatively, examples include resins such as polyamide resin, polyimide resin, aramid resin, or epoxy resin, inorganic vapor-deposited films, or papers.

[0251] Alternatively, a flexible substrate may be used as the substrate, and the light-emitting device may be formed directly on the flexible substrate. Or, a release layer may be provided between the substrate and the light-emitting device. The release layer can be used to separate the light-emitting device from the substrate after it has been partially or completely completed on it, and to transfer it to another substrate. In this case, the light-emitting device can be transferred to a substrate with poor heat resistance or a flexible substrate. The release layer can be configured in various ways, such as a laminated inorganic film structure of a tungsten film and a silicon oxide film, or a resin film such as polyimide formed on the substrate.

[0252] In other words, a light-emitting device may be formed using one substrate, then the light-emitting device may be transferred to another substrate, and the light-emitting device may be placed on the other substrate. Examples of substrates to which the light-emitting device is transferred include, in addition to the substrates mentioned above, cellophane substrates, stone substrates, wood substrates, cloth substrates (including natural fibers (silk, cotton, linen), synthetic fibers (nylon, polyurethane, polyester), or recycled fibers (acetate, cupro, rayon, recycled polyester), etc.), leather substrates, or rubber substrates. By using these substrates, it is possible to create light-emitting devices that are less prone to breakage, have high heat resistance, are lightweight, or are thin.

[0253] Alternatively, a field-effect transistor (FET), for example, may be formed on the aforementioned substrate, and a light-emitting device may be fabricated on an electrode electrically connected to the FET. This makes it possible to fabricate an active-matrix type display device in which the driving of the light-emitting device is controlled by the FET.

[0254] The configuration shown in this embodiment can be used in appropriate combination with the configurations shown in other embodiments.

[0255] (Embodiment 3) As illustrated in Figure 7(B), multiple light-emitting devices 130 are formed on the insulating layer 175 to constitute a display device. In this embodiment, a display device according to one aspect of the present invention will be described in detail.

[0256] The display device 100 has a pixel section 177 in which a plurality of pixels 178 are arranged in a matrix. The pixels 178 include sub-pixels 110R, sub-pixels 110G, and sub-pixels 110B.

[0257] In this specification, for example, when describing matters common to sub-pixels 110R, 110G, and 110B, they may be referred to simply as sub-pixel 110. Similarly, when describing matters common to other components distinguished by letters, the letters may be omitted and the corresponding symbols used.

[0258] Sub-pixel 110R emits red light, sub-pixel 110G emits green light, and sub-pixel 110B emits blue light. This allows an image to be displayed on the pixel section 177. In this embodiment, three sub-pixels of red (R), green (G), and blue (B) are used as an example, but other combinations of sub-pixels of other colors may be used. Furthermore, the number of sub-pixels is not limited to three, but may be four or more. Examples of four sub-pixels include four sub-pixels of R, G, B, and white (W), four sub-pixels of R, G, B, and yellow (Y), and four sub-pixels of R, G, B, and infrared (IR).

[0259] In this specification and other documents, the row direction is sometimes referred to as the X direction, and the column direction as the Y direction. The X and Y directions intersect, for example, perpendicularly.

[0260] Figure 7(A) shows an example where subpixels of different colors are arranged in the X direction, and subpixels of the same color are arranged in the Y direction. Alternatively, subpixels of different colors may be arranged in the Y direction, and subpixels of the same color may be arranged in the X direction.

[0261] A connecting portion 140 and a region 141 may be provided on the outside of the pixel portion 177. The region 141 is provided between the pixel portion 177 and the connecting portion 140. An organic compound layer 103 is provided in the region 141. A conductive layer 151C is provided in the connecting portion 140.

[0262] Figure 7(A) shows an example where region 141 and connection portion 140 are located to the right of the pixel portion 177, but the positions of region 141 and connection portion 140 are not particularly limited. Also, region 141 and connection portion 140 may be singular or plural.

[0263] Figure 7(B) is an example of a cross-sectional view between the dashed line A1-A2 in Figure 7(A). As shown in Figure 7(A), the display device 100 has an insulating layer 171, a conductive layer 172 on the insulating layer 171, an insulating layer 173 on the insulating layer 171 and on the conductive layer 172, an insulating layer 174 on the insulating layer 173, and an insulating layer 175 on the insulating layer 174. The insulating layer 171 is provided on a substrate (not shown). The insulating layer 175, insulating layer 174, and insulating layer 173 are provided with openings that reach the conductive layer 172, and plugs 176 are provided to fill these openings.

[0264] In the pixel section 177, a light-emitting device 130 is provided on an insulating layer 175 and a plug 176. A protective layer 135 is also provided so as to cover the light-emitting device 130. A substrate 120 is bonded to the protective layer 135 by a resin layer 122. Preferably, an inorganic insulating layer 125 and an insulating layer 127 on the inorganic insulating layer 125 are provided between adjacent light-emitting devices 130.

[0265] In Figure 7(B), multiple cross-sections of the inorganic insulating layer 125 and the insulating layer 127 are shown, but when the display device 100 is viewed from above, it is preferable that the inorganic insulating layer 125 and the insulating layer 127 are connected as one unit. In other words, it is preferable that the inorganic insulating layer 125 and the insulating layer 127 are insulating layers having an opening on the first electrode.

[0266] In Figure 7(B), the light-emitting device 130 is shown as light-emitting device 130R, light-emitting device 130G, and light-emitting device 130B. Light-emitting devices 130R, 130G, and 130B emit light of different colors from each other. For example, light-emitting device 130R can emit red light, light-emitting device 130G can emit green light, and light-emitting device 130B can emit blue light. In addition, light-emitting devices 130R, 130G, or 130B may emit other visible light or infrared light.

[0267] One embodiment of the present invention can be a top-emission type, for example, which emits light in the opposite direction to the substrate on which the light-emitting device is formed. Alternatively, one embodiment of the present invention may be a bottom-emission type.

[0268] Examples of light-emitting materials for the light-emitting device 130 include organic compounds or organometallic complexes such as fluorescent materials, phosphorescent materials, and thermally activated delayed fluorescence (TADF) materials. Inorganic compounds such as quantum dots may also be used.

[0269] The light-emitting device 130R has the configuration shown in Embodiment 1. It includes a first electrode (pixel electrode) consisting of a conductive layer 151R and a conductive layer 152R, an organic compound layer 103R on the first electrode, a common layer 104 on the organic compound layer 103R, and a common electrode 155 on the common layer 104. The common electrode 155 corresponds to the second electrode 102 in Embodiments 1 and 2. The common layer 104 may or may not be provided, but its provision is preferable because it reduces damage to the organic compound layer 103R during processing. If the common layer 104 is provided, it is preferable that the common layer 104 is an electron injection layer. If the common layer 104 is not provided, the organic compound layer 103R corresponds to the organic compound layer 103 in Embodiments 1 and 2. If the common layer 104 is provided, the laminated structure of the organic compound layer 103R and the common layer 104 corresponds to the organic compound layer 103 in Embodiments 1 and 2.

[0270] The light-emitting device 130G has the configuration shown in Embodiment 1. It includes a first electrode (pixel electrode) consisting of a conductive layer 151G and a conductive layer 152G, an organic compound layer 103G on the first electrode, a common layer 104 on the organic compound layer 103G, and a common electrode 155 on the common layer 104. The common electrode 155 corresponds to the second electrode 102 in Embodiments 1 and 2. The common layer 104 may or may not be provided, but its provision is preferable because it reduces damage to the organic compound layer 103G during processing. If the common layer 104 is not provided, the organic compound layer 103G corresponds to the organic compound layer 103 in Embodiments 1 and 2. If the common layer 104 is provided, the laminated structure of the organic compound layer 103G and the common layer 104 corresponds to the organic compound layer 103 in Embodiments 1 and 2.

[0271] The light-emitting device 130B has the configuration shown in Embodiment 1. It includes a first electrode (pixel electrode) consisting of a conductive layer 151B and a conductive layer 152B, an organic compound layer 103B on the first electrode, a common layer 104 on the organic compound layer 103B, and a common electrode 155 on the common layer 104. The common electrode 155 corresponds to the second electrode 102 in Embodiments 1 and 2. The common layer 104 may or may not be provided, but its provision is preferable because it reduces damage to the organic compound layer 103B during processing. If the common layer 104 is not provided, the organic compound layer 103B corresponds to the organic compound layer 103 in Embodiments 1 and 2. If the common layer 104 is provided, the laminated structure of the organic compound layer 103B and the common layer 104 corresponds to the organic compound layer 103 in Embodiments 1 and 2.

[0272] Of the pixel electrodes and common electrodes in a light-emitting device, one functions as the anode and the other as the cathode. In the following explanation, unless otherwise specified, it is assumed that the pixel electrodes function as the anode and the common electrodes function as the cathode.

[0273] The organic compound layers 103R, 103G, and 103B are independently arranged in island-like configurations for each light-emitting device or for each light-emitting color. By providing the organic compound layer 103 in island-like configurations for each light-emitting device 130, leakage current between adjacent light-emitting devices 130 can be suppressed even in high-definition display devices. This prevents crosstalk and enables the realization of a display device with extremely high contrast. In particular, it enables the realization of a display device with high current efficiency at low brightness levels.

[0274] The island-shaped organic compound layers 103 are formed by depositing an EL film and processing the EL film using lithography.

[0275] Furthermore, in a display device according to one aspect of the present invention, it is preferable that the first electrode (pixel electrode) of the light-emitting device be in a stacked configuration. For example, in the example shown in Figure 7(B), the first electrode of the light-emitting device 130 is in a stacked configuration of conductive layer 151 (151R, 151G, 151B) and conductive layer 152 (152R, 152G, 152B). For example, when the display device 100 is a top-emission type and the pixel electrode of the light-emitting device 130 functions as an anode, it is preferable that the conductive layer 151 is a layer with high reflectivity for visible light, and the conductive layer 152 is a layer that, for example, transmits visible light and has a large work function. When the display device 100 is a top-emission type, the higher the reflectivity of the pixel electrode for visible light, the higher the efficiency of extracting light emitted by the organic compound layer 103. Also, when the pixel electrode functions as an anode, the larger the work function of the pixel electrode, the easier it is to inject holes into the organic compound layer 103. Based on the above, by using a laminated configuration of a conductive layer 151 with high reflectivity for visible light and a conductive layer 152 with a large work function for the pixel electrodes of the light-emitting device 130, the light-emitting device 130 can be made into a light-emitting device with high light extraction efficiency and low driving voltage. In this specification, when describing matters common to conductive layer 151R, conductive layer 151G, and conductive layer 151B, they may be referred to as conductive layer 151.

[0276] When the conductive layer 151 is a layer with high reflectivity to visible light, it is preferable that the reflectivity of the conductive layer 151 to visible light be, for example, 40% to 100% or 70% to 100%. Furthermore, when the conductive layer 152 is an electrode that transmits visible light, it is preferable that its transmittance to visible light be, for example, 40% or more.

[0277] In cases where the pixel electrode has a stacked structure consisting of multiple layers, the pixel electrode may be altered due to reactions between these layers, for example. For instance, when a film formed after the pixel electrode is created is removed by a wet etching method, galvanic corrosion may occur when the chemical solution comes into contact with the pixel electrode.

[0278] Therefore, in the display device 100 of this embodiment, insulating layers 156 (156R, 156G, 156B) are formed on the sides of the conductive layers 151 and 152. This makes it possible to suppress contact between the chemical solution and the conductive layer 151, even when removing a film formed after the formation of a pixel electrode having the conductive layer 151 and the conductive layer 152 by a wet etching method. Thus, for example, the occurrence of galvanic corrosion on the pixel electrode can be suppressed. As a result, the display device 100 can be manufactured using a method with a high yield, making it a low-cost display device. Furthermore, since the occurrence of defects in the display device 100 can be suppressed, the display device 100 can be a highly reliable display device. In this specification, when describing matters common to insulating layers 156R, 156G, and 156B, they may be referred to as insulating layer 156.

[0279] For example, a metallic material can be used as the conductive layer 151. Specifically, metals such as aluminum (Al), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), gallium (Ga), zinc (Zn), indium (In), tin (Sn), molybdenum (Mo), tantalum (Ta), tungsten (W), palladium (Pd), gold (Au), platinum (Pt), silver (Ag), yttrium (Y), neodymium (Nd), and alloys containing these in appropriate combinations can also be used.

[0280] As the conductive layer 152, an oxide having one or more selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon can be used. For example, it is preferable to use a conductive oxide containing one or more of the following: indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, zinc oxide containing gallium, titanium oxide, indium zinc oxide containing gallium, indium zinc oxide containing aluminum, indium tin oxide containing silicon, and indium zinc oxide containing silicon. In particular, indium tin oxide containing silicon has a large work function, for example, a work function of 4.0 eV or more, so it can be suitably used as the conductive layer 152.

[0281] The conductive layer 151 may be a laminated structure of multiple layers having different materials, and the conductive layer 152 may be a laminated structure of multiple layers having different materials. In this case, the conductive layer 151 may have a layer made of a material that can be used for the conductive layer 152, such as a conductive oxide, and the conductive layer 152 may have a layer made of a material that can be used for the conductive layer 151, such as a metallic material. For example, if the conductive layer 151 has a laminated structure of two or more layers, the layer in contact with the conductive layer 152 may be a layer made of a material that can be used for the conductive layer 152.

[0282] The configuration of this embodiment can be used in appropriate combination with the configurations of other embodiments.

[0283] (Embodiment 4) In this embodiment, a light-emitting device according to one aspect of the present invention will be described using Figures 8(A) to 8(G) and Figures 9(A) to 9(I).

[0284] [Pixel layout] This embodiment primarily describes a pixel layout different from that shown in Figure 7(A). There are no particular limitations on the arrangement of subpixels, and various methods can be applied. Examples of subpixel arrangements include stripe arrangements, S-stripe arrangements, matrix arrangements, delta arrangements, Bayer arrangements, and pentile arrangements.

[0285] In this embodiment, the upper surface shape of the sub-pixel shown in the figure corresponds to the upper surface shape of the light-emitting region.

[0286] Examples of the top surface shape of a sub-pixel include polygons such as triangles, quadrilaterals (including rectangles and squares), pentagons, polygons with rounded corners, ellipses, or circles.

[0287] Furthermore, the circuit layout constituting the sub-pixel is not limited to the sub-pixel range shown in the figure, but may be arranged outside of it.

[0288] The pixel 178 shown in Figure 8(A) has an S-stripe array applied to it. The pixel 178 shown in Figure 8(A) is composed of three subpixels: subpixel 110R, subpixel 110G, and subpixel 110B.

[0289] The pixel 178 shown in Figure 8(B) has sub-pixels 110R with a roughly trapezoidal or triangular top surface shape with rounded corners, sub-pixel 110G with a roughly trapezoidal or triangular top surface shape with rounded corners, and sub-pixel 110B with a roughly square or hexagonal top surface shape with rounded corners. Furthermore, sub-pixel 110R has a larger light-emitting area than sub-pixel 110G. In this way, the shape and size of each sub-pixel can be determined independently. For example, the size of a sub-pixel can be reduced to a smaller size if it has a more reliable light-emitting device.

[0290] A Pentile array is applied to pixels 124a and 124b shown in Figure 8(C). Figure 8(C) shows an example in which pixels 124a having sub-pixels 110R and 110G and pixels 124b having sub-pixels 110G and 110B are arranged alternately.

[0291] Pixels 124a and 124b shown in Figures 8(D) to 8(F) are fitted with a delta array. Pixel 124a has two subpixels (subpixels 110R and 110G) in the top row (1st row) and one subpixel (subpixel 110B) in the bottom row (2nd row). Pixel 124b has one subpixel (subpixel 110B) in the top row (1st row) and two subpixels (subpixels 110R and 110G) in the bottom row (2nd row).

[0292] Figure 8(D) shows an example where each subpixel has a roughly square top shape with rounded corners, Figure 8(E) shows an example where each subpixel has a circular top shape, and Figure 8(F) shows an example where each subpixel has a roughly hexagonal top shape with rounded corners.

[0293] In Figure 8(F), each subpixel is located inside a densely arranged hexagonal region. When focusing on one subpixel, it is surrounded by six other subpixels. Furthermore, subpixels that emit light of the same color are not adjacent to each other. For example, when focusing on subpixel 110R, three subpixels 110G and three subpixels 110B are arranged alternately around it.

[0294] Figure 8(G) shows an example where the subpixels of each color are arranged in a zigzag pattern. Specifically, in a top view, the upper edges of two subpixels aligned in the row direction (for example, subpixel 110R and subpixel 110G, or subpixel 110G and subpixel 110B) are offset.

[0295] In each pixel shown in Figures 8(A) to 8(G), it is preferable, for example, that sub-pixel 110R emits red light, sub-pixel 110G emits green light, and sub-pixel 110B emits blue light. However, the configuration of the sub-pixels is not limited to this, and the colors emitted by the sub-pixels and their order can be determined as appropriate. For example, sub-pixel 110G may emit red light, and sub-pixel 110R may emit green light.

[0296] In photolithography, the finer the pattern being processed, the more significant the effects of light diffraction become. This compromises the fidelity of transferring the photomask pattern through exposure, making it difficult to process the resist mask into the desired shape. Therefore, even if the photomask pattern is rectangular, patterns with rounded corners are likely to form. Consequently, the top surface shape of subpixels may be a polygon with rounded corners, an ellipse, or a circle.

[0297] Furthermore, in a method for manufacturing a light-emitting device according to one embodiment of the present invention, an organic compound layer is processed into an island shape using a resist mask. The resist film formed on the organic compound layer needs to be cured at a temperature lower than the heat resistance temperature of the organic compound layer. Therefore, depending on the heat resistance temperature of the organic compound layer material and the curing temperature of the resist material, the curing of the resist film may be insufficient. A resist film that is not sufficiently cured may take a shape that deviates from the desired shape during processing. As a result, the top surface shape of the organic compound layer may become a polygon with rounded corners, an ellipse, or a circle. For example, if an attempt is made to form a resist mask with a square top surface, a resist mask with a circular top surface may be formed, resulting in a circular top surface shape for the organic compound layer.

[0298] Furthermore, in order to achieve the desired shape of the upper surface of the organic compound layer, a technique (OPC (Optical Proximity Correction) technique) may be used to pre-correct the mask pattern so that the design pattern and the transferred pattern match. Specifically, in the OPC technique, for example, a correction pattern is added to the corners of the shape on the mask pattern.

[0299] As shown in Figures 9(A) to 9(I), a pixel can be configured to have four types of subpixels.

[0300] Pixel 178, shown in Figures 9(A) to 9(C), has a stripe arrangement applied to it.

[0301] Figure 9(A) shows an example where each subpixel has a rectangular top surface shape, Figure 9(B) shows an example where each subpixel has a top surface shape formed by connecting two semicircles and a rectangle, and Figure 9(C) shows an example where each subpixel has an elliptical top surface shape.

[0302] Pixel 178, shown in Figures 9(D) to 9(F), has a matrix array applied to it.

[0303] Figure 9(D) shows an example where each subpixel has a square top surface shape, Figure 9(E) shows an example where each subpixel has a roughly square top surface shape with rounded corners, and Figure 9(F) shows an example where each subpixel has a circular top surface shape.

[0304] Figures 9(G) and 9(H) show an example where one pixel 178 is composed of 2 rows and 3 columns.

[0305] Pixel 178, shown in Figure 9(G), has three subpixels (subpixels 110R, 110G, and 110B) in the top row (row 1) and one subpixel (subpixel 110W) in the bottom row (row 2). In other words, pixel 178 has subpixel 110R in the left column (column 1), subpixel 110G in the middle column (column 2), subpixel 110B in the right column (column 3), and subpixel 110W across these three columns.

[0306] Pixel 178, shown in Figure 9(H), has three subpixels (subpixels 110R, 110G, and 110B) in the top row (1st row) and three subpixels 110W in the bottom row (2nd row). In other words, pixel 178 has subpixels 110R and 110W in the left column (1st column), subpixels 110G and 110W in the middle column (2nd column), and subpixels 110B and 110W in the right column (3rd column). As shown in Figure 9(H), by aligning the arrangement of subpixels in the top row and bottom row, it becomes possible to efficiently remove dust that may be generated during the manufacturing process, for example. Therefore, a light-emitting device with high display quality can be provided.

[0307] In pixel 178 shown in Figures 9(G) and 9(H), the layout of sub-pixels 110R, 110G, and 110B is in a stripe arrangement, which improves the display quality.

[0308] Figure 9(I) shows an example where one pixel, 178, is composed of 3 rows and 2 columns.

[0309] Pixel 178, shown in Figure 9(I), has a sub-pixel 110R in the top row (1st row), a sub-pixel 110G in the middle row (2nd row), a sub-pixel 110B spanning from the 1st to the 2nd row, and one sub-pixel (sub-pixel 110W) in the bottom row (3rd row). In other words, pixel 178 has sub-pixels 110R and 110G in the left column (1st column), a sub-pixel 110B in the right column (2nd column), and a sub-pixel 110W spanning these two columns.

[0310] In pixel 178 shown in Figure 9(I), the layout of sub-pixels 110R, 110G, and 110B forms a so-called S-stripe arrangement, which improves display quality.

[0311] The pixel 178 shown in Figures 9(A) to 9(I) is composed of four subpixels: subpixel 110R, subpixel 110G, subpixel 110B, and subpixel 110W. For example, subpixel 110R may be a subpixel that emits red light, subpixel 110G may be a subpixel that emits green light, subpixel 110B may be a subpixel that emits blue light, and subpixel 110W may be a subpixel that emits white light. At least one of subpixels 110R, 110G, 110B, and 110W may be a subpixel that emits cyan light, a subpixel that emits magenta light, a subpixel that emits yellow light, or a subpixel that emits near-infrared light.

[0312] As described above, the light-emitting device according to one aspect of the present invention can be configured to apply various layouts to pixels that consist of subpixels having light-emitting devices.

[0313] This embodiment can be appropriately combined with other embodiments or examples. Furthermore, if multiple configuration examples are shown within a single embodiment in this specification, these configuration examples can be appropriately combined.

[0314] (Embodiment 5) This embodiment describes a light-emitting device according to one aspect of the present invention.

[0315] The light-emitting device of this embodiment can be a high-definition light-emitting device. Therefore, the light-emitting device of this embodiment can be used, for example, in the display units of information terminals (wearable devices) such as wristwatches and bracelets, and in the display units of wearable devices that can be worn on the head, such as VR devices such as head-mounted displays (HMDs) and AR devices such as glasses.

[0316] Furthermore, the light-emitting device of this embodiment can be a high-resolution light-emitting device or a large light-emitting device. Therefore, the light-emitting device of this embodiment can be used in electronic devices with relatively large screens, such as television systems, desktop or notebook personal computers, monitors for computers, 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, personal information terminals, and sound playback devices.

[0317] [Display Module] Figure 10(A) shows a perspective view of the display module 280. The display module 280 includes a display device 100A and an FPC 290. Note that the light-emitting device of the display module 280 is not limited to the display device 100A, but may be any of the display devices 100B to 100F described later.

[0318] 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.

[0319] 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.

[0320] The pixel section 284 has a plurality of pixels 284a arranged periodically. A magnified view of one pixel 284a is shown on the right side of Figure 10(B). Various configurations described in the previous embodiment can be applied to the pixel 284a. Figure 10(B) shows an example where the pixel 284a has the same configuration as the pixel 178 shown in Figure 7(A).

[0321] The pixel circuit section 283 has a plurality of pixel circuits 283a arranged periodically.

[0322] A single pixel circuit 283a is a circuit that controls the driving of multiple elements in a single pixel 284a. A single pixel circuit 283a can be configured to have three circuits that control the light emission of a single light-emitting device. For example, a single pixel circuit 283a can be configured to have at least one selection transistor, one current control transistor (drive transistor), and a capacitor for each light-emitting device. In this case, a gate signal is input to the gate of the selection transistor, and a video signal is input to the source or drain. This realizes an active-matrix type light-emitting device.

[0323] 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.

[0324] 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.

[0325] 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 are arranged in the display section 281 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 a resolution of 20000 ppi or less, or 30000 ppi or less.

[0326] Because such a display module 280 is extremely high-resolution, it can be suitably used in VR devices such as HMDs or AR devices such as glasses. 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, and a highly immersive display can be achieved. 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 watches.

[0327] [Display device 100A] The display device 100A shown in Figure 11(A) includes a substrate 301, light-emitting devices 130R, 130G, 130B, a capacitor 240, and a transistor 310.

[0328] Substrate 301 corresponds to substrate 291 in Figures 10(A) and 10(B). Transistor 310 is a transistor having a channel formation region in substrate 301. For substrate 301, a semiconductor substrate such as a single-crystal silicon substrate can be used. Transistor 310 has a part of 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 substrate 301 and the conductive layer 311 and functions as a gate insulating layer. The low-resistance region 312 is a region of substrate 301 doped with impurities and functions as a source or drain. The insulating layer 314 is provided covering the side surface of the conductive layer 311.

[0329] Furthermore, an element isolation layer 315 is provided between two adjacent transistors 310 so as to be embedded in the substrate 301.

[0330] Furthermore, an insulating layer 261 is provided covering the transistor 310, and a capacitance 240 is provided on the insulating layer 261.

[0331] The capacitor 240 has a conductive layer 241, a conductive layer 245, and an insulating layer 243 located between them. The conductive layer 241 acts as one electrode of the capacitor 240, the conductive layer 245 acts as the other electrode of the capacitor 240, and the insulating layer 243 acts as the dielectric of the capacitor 240.

[0332] 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.

[0333] An insulating layer 255 is provided covering the capacitance 240, an insulating layer 174 is provided on the insulating layer 255, and an insulating layer 175 is provided on the insulating layer 174. Light-emitting devices 130R, 130G, and 130B are provided on the insulating layer 175. Figure 11(A) shows an example in which light-emitting devices 130R, 130G, and 130B have the layered structure shown in Figure 1(A). An insulator is provided in the region between adjacent light-emitting devices. For example, in Figure 11(A), an inorganic insulating layer 125 and an insulating layer 127 on the inorganic insulating layer 125 are provided in this region.

[0334] An insulating layer 156R is provided so as to have a region that overlaps with the side surface of the conductive layer 151R of the light-emitting device 130R, an insulating layer 156G is provided so as to have a region that overlaps with the side surface of the conductive layer 151G of the light-emitting device 130G, and an insulating layer 156B is provided so as to have a region that overlaps with the side surface of the conductive layer 151B of the light-emitting device 130B. In addition, a conductive layer 152R is provided so as to cover the conductive layer 151R and the insulating layer 156R, a conductive layer 152G is provided so as to cover the conductive layer 151G and the insulating layer 156G, and a conductive layer 152B is provided so as to cover the conductive layer 151B and the insulating layer 156B. Furthermore, a sacrificial layer 158R is located on the organic compound layer 103R of the light-emitting device 130R, a sacrificial layer 158G is located on the organic compound layer 103G of the light-emitting device 130G, and a sacrificial layer 158B is located on the organic compound layer 103B of the light-emitting device 130B.

[0335] The conductive layers 151R, 151G, and 151B are electrically connected to either the source or drain of the transistor 310 by the insulating layers 243, 255, 174, and a plug 256 embedded in the insulating layer 175, a conductive layer 241 embedded in the insulating layer 254, and a plug 271 embedded in the insulating layer 261. The height of the top surface of the insulating layer 175 and the height of the top surface of the plug 256 are equal or approximately equal. Various conductive materials can be used for the plugs.

[0336] Furthermore, a protective layer 135 is provided on the light-emitting devices 130R, 130G, and 130B. A substrate 120 is bonded to the protective layer 135 by a resin layer 122. Details of the components from the light-emitting device 130 to the substrate 120 can be found in Embodiment 3. The substrate 120 corresponds to the substrate 292 in Figure 10(A).

[0337] Figure 11(B) shows a modified example of the display device 100A shown in Figure 11(A). The light-emitting device shown in Figure 11(B) has a colored layer 136R, a colored layer 136G, and a colored layer 136B, and the light-emitting device 130 has a region that overlaps with one of the colored layers 136R, 136G, and 136B. In the light-emitting device shown in Figure 11(B), the light-emitting device 130 can emit, for example, white light. Also, for example, the colored layer 136R can transmit red light, the colored layer 136G can transmit green light, and the colored layer 136B can transmit blue light.

[0338] [Display device 100B] Figure 12 shows a perspective view of the display device 100B, and Figure 13(A) shows a cross-sectional view of the display device 100B.

[0339] The display device 100B has a configuration in which substrate 352 and substrate 351 are bonded together. In Figure 12, substrate 352 is clearly indicated by a dashed line.

[0340] The display device 100B includes a pixel section 177, a connection section 140, a circuit 356, and wiring 355, etc. Figure 12 shows an example in which an IC (integrated circuit) 354 and an FPC 353 are mounted on the display device 100B. Therefore, the configuration shown in Figure 12 can also be called a display module having the display device 100B, an IC, and an FPC. Here, a display module is defined as a circuit board of a light-emitting device with connectors such as an FPC attached, or a circuit board on which an IC is mounted.

[0341] The connection portion 140 is provided on the outside of the pixel portion 177. The connection portion 140 can be provided along one or more sides of the pixel portion 177. There may be one or more connection portions 140. Figure 12 shows an example in which the connection portion 140 is provided so as to surround all four sides of the pixel portion 177. At the connection portion 140, the common electrode of the light-emitting device and the conductive layer are electrically connected, and a potential can be supplied to the common electrode.

[0342] For example, a scan line drive circuit can be used as circuit 356.

[0343] The wiring 355 has the function of supplying signals and power to the pixel unit 177 and the circuit 356. These signals and power are input to the wiring 355 from an external source via the FPC 353 or from the IC 354.

[0344] Figure 12 shows an example in which IC 354 is mounted on substrate 351 using COG (Chip On Glass) or COF (Chip On Film) methods. IC 354 can be an IC having, for example, a scan line drive circuit or a signal line drive circuit. Note that the display device 100B and the display module may be configured without an IC. Alternatively, the IC may be mounted on an FPC, for example, using the COF method.

[0345] Figure 13(A) shows an example of a cross-section of the display device 100B when a portion of the area including the FPC 353, a portion of the circuit 356, a portion of the pixel portion 177, a portion of the connection portion 140, and a portion of the area including the end portion are cut.

[0346] The display device 100B shown in Figure 13(A) has a transistor 201, a transistor 205, a light-emitting device 130R that emits red light, a light-emitting device 130G that emits green light, and a light-emitting device 130B that emits blue light, etc., between substrates 351 and 352.

[0347] Light-emitting devices 130R, 130G, and 130B each have the stacked structure shown in Figure 1(A), except that they differ in the configuration of their pixel electrodes. Details of the light-emitting devices can be found in the previous embodiment.

[0348] Light-emitting device 130R has a conductive layer 224R, a conductive layer 151R on the conductive layer 224R, and a conductive layer 152R on the conductive layer 151R. Light-emitting device 130G has a conductive layer 224G, a conductive layer 151G on the conductive layer 224G, and a conductive layer 152G on the conductive layer 151G. Light-emitting device 130B has a conductive layer 224B, a conductive layer 151B on the conductive layer 224B, and a conductive layer 152B on the conductive layer 151B. Here, the conductive layers 224R, 151R, and 152R can all be collectively called the pixel electrodes of light-emitting device 130R, and the conductive layers 151R and 152R excluding the conductive layer 224R can also be called the pixel electrodes of light-emitting device 130R. Similarly, conductive layers 224G, 151G, and 152G can all be collectively referred to as the pixel electrodes of the light-emitting device 130G, and conductive layers 151G and 152G (excluding conductive layer 224G) can also be referred to as the pixel electrodes of the light-emitting device 130G. Furthermore, conductive layers 224B, 151B, and 152B can all be collectively referred to as the pixel electrodes of the light-emitting device 130B, and conductive layers 151B and 152B (excluding conductive layer 224B) can also be referred to as the pixel electrodes of the light-emitting device 130B.

[0349] The conductive layer 224R is connected to the conductive layer 222b of the transistor 205 through an opening provided in the insulating layer 214. The edge of the conductive layer 151R is located outside the edge of the conductive layer 224R. The insulating layer 156R is provided so as to have a region in contact with the side surface of the conductive layer 151R, and the conductive layer 152R is provided so as to cover the conductive layer 151R and the insulating layer 156R.

[0350] The conductive layers 224G, 151G, 152G, and insulating layer 156G in the light-emitting device 130G, and the conductive layers 224B, 151B, 152B, and insulating layer 156B in the light-emitting device 130B are the same as the conductive layers 224R, 151R, 152R, and insulating layer 156R in the light-emitting device 130R, so a detailed explanation is omitted.

[0351] The conductive layer 224R, conductive layer 224G, and conductive layer 224B have recesses formed to cover the openings provided in the insulating layer 214. Layer 128 is embedded in these recesses.

[0352] Layer 128 has the function of flattening the recesses of conductive layers 224R, 224G, and 224B. Conductive layers 151R, 151G, and 151B are provided on conductive layers 224R, 224G, and 224B and on layer 128, and are electrically connected to conductive layers 224R, 224G, and 224B. Therefore, regions overlapping with the recesses of conductive layers 224R, 224G, and 224B can also be used as light-emitting regions, thereby increasing the aperture ratio of the pixels.

[0353] Layer 128 may be an insulating layer or a conductive layer. Various inorganic insulating materials, organic insulating materials, and conductive materials can be used for layer 128 as appropriate. In particular, it is preferable that layer 128 be formed using an insulating material, and especially preferable that it be formed using an organic insulating material. For example, an organic insulating material that can be used for the insulating layer 127 described above can be applied to layer 128.

[0354] A protective layer 135 is provided on the light-emitting devices 130R, 130G, and 130B. The protective layer 135 and the substrate 352 are bonded via an adhesive layer 142. A light-shielding layer 157 is provided on the substrate 352. A solid encapsulation structure or a hollow encapsulation structure can be applied to encapsulate the light-emitting devices 130. In Figure 13(A), the space between the substrate 352 and the substrate 351 is filled with the adhesive layer 142, indicating a solid encapsulation structure. Alternatively, the space may be filled with an inert gas (such as nitrogen or argon), indicating a hollow encapsulation structure. In this case, the adhesive layer 142 may be provided in a frame shape so as not to overlap with the light-emitting devices. Furthermore, the space may be filled with a resin different from the adhesive layer 142 provided in a frame shape.

[0355] Figure 13(A) shows an example in which the connection portion 140 has a conductive layer 224C obtained by processing the same conductive film as conductive layers 224R, 224G, and 224B; a conductive layer 151C obtained by processing the same conductive film as conductive layers 151R, 151G, and 151B; and a conductive layer 152C obtained by processing the same conductive film as conductive layers 152R, 152G, and 152B. Figure 13(A) also shows an example in which an insulating layer 156C is provided so as to have a region that overlaps with the side surface of conductive layer 151C.

[0356] The display device 100B is a top-emission type. The light emitted by the light-emitting device is emitted towards the substrate 352. It is preferable to use a material with high transmittance to visible light for the substrate 352. The pixel electrodes contain a material that reflects visible light, and the counter electrodes (common electrodes 155) contain a material that transmits visible light.

[0357] Both transistors 201 and 205 are formed on the substrate 351. These transistors can be manufactured using the same materials and processes.

[0358] On the substrate 351, 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.

[0359] 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, and the reliability of the light-emitting device can be improved.

[0360] 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 oxynitride film, silicon oxide film, silicon nitride oxide film, aluminum oxide film, or 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.

[0361] An organic insulating layer is preferred for the insulating layer 214, which functions as a planarizing layer. Examples of materials that can be used for the organic insulating layer include acrylic resin, polyimide resin, epoxy resin, polyamide resin, polyimidoamide resin, siloxane resin, benzocyclobutene resin, phenol resin, and precursors of these resins. Alternatively, the insulating layer 214 may have a laminated structure of an organic insulating layer and an inorganic insulating layer. The outermost layer of the insulating layer 214 preferably functions as an etching protection layer. This suppresses the formation of depressions in the insulating layer 214 during processing of the conductive layer 224R, conductive layer 151R, or conductive layer 152R, etc. Alternatively, depressions may be provided in the insulating layer 214 during processing of the conductive layer 224R, conductive layer 151R, or conductive layer 152R, etc.

[0362] 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.

[0363] The structure of the transistor in the light-emitting device of this embodiment is not particularly limited. For example, a planar transistor, a staggered transistor, or an inverse staggered transistor 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.

[0364] 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.

[0365] 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.

[0366] The semiconductor layer of the transistor preferably has a metal oxide. In other words, the light-emitting 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.

[0367] Examples of crystalline oxide semiconductors include CAAC (c-axis-aligned crystalline)-OS and nc (nanocrystalline)-OS.

[0368] Alternatively, a transistor using silicon as the channel-forming region (Si transistor) may be used. Examples of silicon include single-crystal silicon, polycrystalline silicon, or amorphous silicon. In particular, a transistor having low-temperature polysilicon (LTPS (Low Temperature Poly Silicon)) in the semiconductor layer (hereinafter also referred to as an LTPS transistor) can be used. LTPS transistors have high field-effect mobility and good frequency characteristics.

[0369] By using Si transistors such as LTPS transistors, circuits that need to be driven at high frequencies (e.g., source driver circuits) can be fabricated on the same board as the display unit. This simplifies the external circuits mounted on the light-emitting device, reducing component and mounting costs.

[0370] OS transistors exhibit extremely high field-effect mobility compared to transistors using amorphous silicon. Furthermore, OS transistors have remarkably low source-drain leakage current in the off state, allowing them to retain charge stored in a capacitor connected in series with the transistor for extended periods. Additionally, the application of OS transistors can reduce the power consumption of light-emitting devices.

[0371] Furthermore, to increase the luminescence brightness of the light-emitting device included in the pixel circuit, it is necessary to increase the amount of current flowing through the light-emitting device. To achieve this, it is necessary to increase the source-drain voltage of the drive transistor included in the pixel circuit. Compared to Si transistors, OS transistors have a higher breakdown voltage between the source and drain, so a higher voltage can be applied between the source and drain of an OS transistor. Therefore, by using an OS transistor as the drive transistor included in the pixel circuit, the amount of current flowing through the light-emitting device can be increased, thereby increasing the luminescence brightness of the light-emitting device.

[0372] Furthermore, in terms of the saturation characteristics of the current flowing when a transistor operates in the saturation region, OS transistors can supply a more stable current (saturation current) than Si transistors, even when the source-drain voltage gradually increases. Therefore, by using an OS transistor as a driving transistor, a stable current can be supplied to a light-emitting device even if there are variations in the current-voltage characteristics of the light-emitting device. In other words, when operating in the saturation region, the source-drain current remains almost unchanged even when the source-drain voltage is increased, thus stabilizing the luminescence brightness of the light-emitting device.

[0373] As described above, by using OS transistors in the drive transistors included in the pixel circuit, it is possible to achieve "suppression of black level floating," "increase in luminescence brightness," "multi-gradation," and "suppression of variations in light-emitting devices."

[0374] 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, it is preferable that M is one or more selected from aluminum, gallium, yttrium, and tin.

[0375] In particular, it is preferable to use an oxide containing indium (In), gallium (Ga), and zinc (Zn) (also written as IGZO) as the semiconductor layer. Alternatively, it is preferable to use an oxide containing indium, tin, and zinc. Alternatively, it is preferable to use an oxide containing indium, gallium, tin, and zinc. Alternatively, it is preferable to use an oxide containing indium (In), aluminum (Al), and zinc (Zn) (also written as IAZO). Alternatively, it is preferable to use an oxide containing indium (In), aluminum (Al), gallium (Ga), and zinc (Zn) (also written as IAGZO). Alternatively, it is preferable to use an oxide containing indium (In) (also written as IO).

[0376] 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 atomic ratios of metal elements in such In-M-Zn oxides 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 "nearby composition" includes a range of ±30% of the desired atomic ratio.

[0377] When the atomic ratio is stated as In:Ga:Zn=4:2:3 or nearby, it includes cases where, with In set to 4, Ga is between 1 and 3, and Zn is between 2 and 4. Furthermore, when the atomic ratio is stated as In:Ga:Zn=5:1:6 or nearby, it includes cases where, with In set to 5, Ga is greater than 0.1 and 2 or less, and Zn is between 5 and 7. Furthermore, when the atomic ratio is stated as In:Ga:Zn=1:1:1 or nearby, it includes cases where, with In set to 1, Ga is greater than 0.1 and 2 or less, and Zn is greater than 0.1 and 2 or less.

[0378] The transistors in circuit 356 and the transistors in pixel unit 177 may have the same structure or different structures. The structures of the multiple transistors in circuit 356 may all be the same or there may be two or more different structures. Similarly, the structures of the multiple transistors in pixel unit 177 may all be the same or there may be two or more different structures.

[0379] All of the transistors in the pixel section 177 may be OS transistors, all of the transistors in the pixel section 177 may be Si transistors, or some of the transistors in the pixel section 177 may be OS transistors and the rest may be Si transistors.

[0380] For example, by using both LTPS transistors and OS transistors in the pixel section 177, a light-emitting device with low power consumption and high driving capability can be realized. Furthermore, a configuration combining LTPS transistors and OS transistors is sometimes referred to as LTPO. It is preferable, for example, to use an OS transistor as a switch to control the conduction and non-conductivity of wiring, and an LTPS transistor as a transistor to control current.

[0381] For example, one of the transistors in the pixel section 177 functions as a transistor for controlling the current flowing to the light-emitting device and can be called a drive transistor. One of the source and drain of the drive transistor is electrically connected to the pixel electrode of the light-emitting device. It is preferable to use an LTPS transistor for this drive transistor. This makes it possible to increase the current flowing to the light-emitting device in the pixel circuit.

[0382] On the other hand, the other transistor in the pixel unit 177 functions as a switch to control the selection and deselection of pixels, and can also be called a selection transistor. The gate of the selection transistor is electrically connected to the gate line, and one of the source and drain is electrically connected to the source line (signal line). It is preferable to use an OS transistor for the selection transistor. This allows the pixel gradation to be maintained even when the frame frequency is significantly reduced (e.g., 1 fps or less), and thus power consumption can be reduced by stopping the driver when displaying still images.

[0383] Thus, a light-emitting device according to one aspect of the present invention can combine a high aperture ratio, high resolution, high display quality, and low power consumption.

[0384] Furthermore, one embodiment of the present invention is a light-emitting device having an OS transistor and a light-emitting device with an MML (metal maskless) structure. This configuration makes it possible to extremely low leakage current that can flow through the transistor and leakage current that can flow between adjacent light-emitting devices (sometimes referred to as lateral leakage current, transverse leakage current, or lateral leakage current). In addition, with this configuration, when an image is displayed on the light-emitting device, the observer can observe one or more of the following: image sharpness, image clarity, high saturation, and high contrast ratio. Moreover, by having an extremely low leakage current that can flow through the transistor and transverse leakage current between light-emitting devices, it is possible to achieve a display with as little light leakage (so-called black floating) that may occur when displaying black as possible.

[0385] In particular, among MML-structured light-emitting devices, applying the SBS (Side By Side) structure, which involves creating or coating different light-emitting layers, results in a configuration where the layers between light-emitting devices (for example, an organic layer used in common between light-emitting devices, also called a common layer) are separated, thus eliminating or significantly reducing side leakage.

[0386] Figures 13(B) and 13(C) show other examples of transistor configurations.

[0387] Transistors 209 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 231 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 at least between the conductive layer 223 and the channel forming region 231i. Furthermore, an insulating layer 218 covering the transistor may be provided.

[0388] In the transistor 209 shown in Figure 13(B), an example is shown where the insulating layer 225 covers the top and sides of the semiconductor layer 231. The conductive layers 222a and 222b are connected to the low-resistance region 231n through openings provided in the insulating layers 225 and 215, respectively. Of the conductive layers 222a and 222b, one functions as the source and the other as the drain.

[0389] On the other hand, in the transistor 210 shown in Figure 13(C), 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 13(C) can be fabricated by processing the insulating layer 225 using the conductive layer 223 as a mask. In Figure 13(C), an insulating layer 215 is provided covering the insulating layer 225 and the conductive layer 223, and the conductive layer 222a and conductive layer 222b are connected to the low-resistance region 231n, respectively, through openings in the insulating layer 215.

[0390] A connection portion 204 is provided in the region of substrate 351 where substrate 352 does not overlap. At the connection portion 204, the wiring 355 is electrically connected to the FPC 353 via the conductive layer 166 and the connecting layer 242. The conductive layer 166 is shown as an example of a laminated structure consisting of a conductive film obtained by processing the same conductive film as conductive layers 224R, 224G, and 224B, a conductive film obtained by processing the same conductive film as conductive layers 151R, 151G, and 151B, and a conductive film obtained by processing the same conductive film as conductive layers 152R, 152G, and 152B. On the upper surface of the connection portion 204, the conductive layer 166 is exposed. This allows the connection portion 204 and the FPC 353 to be electrically connected via the connecting layer 242.

[0391] It is preferable to provide a light-shielding layer 157 on the surface of the substrate 352 that faces the substrate 351. The light-shielding layer 157 can be provided between adjacent light-emitting devices, at connection points 140, and in circuits 356, etc. In addition, various optical components can be arranged on the outside of the substrate 352.

[0392] Materials that can be used for substrate 120 can be applied to substrate 351 and substrate 352, respectively.

[0393] As the adhesive layer 142, a material that can be used for the resin layer 122 can be applied.

[0394] As the connecting layer 242, an anisotropic conductive film (ACF) or an anisotropic conductive paste (ACP) can be used.

[0395] [Display device 100C] The display device 100C shown in Figure 14 differs from the display device 100B shown in Figure 13(A) mainly in that it is a bottom-emission type light-emitting device.

[0396] The light emitted by the light-emitting device is projected onto the substrate 351. It is preferable to use a material with high transparency to visible light for the substrate 351. On the other hand, the light transmittance of the material used for the substrate 352 is not a requirement.

[0397] It is preferable to form a light-shielding layer 157 between the substrate 351 and the transistor 201, and between the substrate 351 and the transistor 205. Figure 14 shows an example in which a light-shielding layer 157 is provided on the substrate 351, an insulating layer 153 is provided on the light-shielding layer 157, and transistors 201, 205, etc. are provided on the insulating layer 153.

[0398] The light-emitting device 130R includes a conductive layer 112R, a conductive layer 126R on the conductive layer 112R, and a conductive layer 129R on the conductive layer 126R.

[0399] The light-emitting device 130B includes a conductive layer 112B, a conductive layer 126B on the conductive layer 112B, and a conductive layer 129B on the conductive layer 126B.

[0400] The conductive layers 112R, 112B, 126R, 126B, 129R, and 129B are made of materials with high transmittance to visible light. It is preferable to use a material that reflects visible light for the common electrode 155.

[0401] Although the light-emitting device 130G is not shown in Figure 14, it is also provided.

[0402] Furthermore, while Figure 14 and others show an example where the upper surface of layer 128 has a flat portion, the shape of layer 128 is not particularly limited.

[0403] [Display device 100D] The display device 100D shown in Figure 15 is a bottom-emission type, but it is an example of a bottom-emission type display device that differs from the display device 100C shown in Figure 14. The display device 100D differs from the display device 100C in that it has an organic resin layer 180. Note that in the figures, the reference numerals for components that are the same as in Figure 14 may be omitted, and details should be referred to in Figure 14.

[0404] Furthermore, Figure 15(B) shows the top view layout of pixels 178 (pixels 178a and 178b) having sub-pixels 110 (sub-pixels 110R, 110G, 110B, and 110W), and Figure 15(C) shows the top view of the organic resin layer 180 in the region where sub-pixels 110R and 110W of pixel 178 are formed. The width 110Rw of the light-emitting region of sub-pixel 110R is between the light-shielding layers 317.

[0405] As shown in Figure 15(A), the organic resin layer 180 is provided on the insulating layer 214. As shown in the region enclosed by the dashed line in Figure 15(A) and in Figure 15(C), the organic resin layer 180 has curved recesses 181 (recesses 181a, recesses 181b) in at least the region where subpixels are formed. The recesses 181 may also be provided outside the light-emitting region, such as recess 181c. By providing recess 181c, the light emitted in the region overlapping with the light-shielding layer 317 or the light that has traveled to the region overlapping with the light-shielding layer 317 can be refracted and extracted from the light-emitting region, thereby improving the luminous efficiency.

[0406] Multiple recesses 181 may be formed in a matrix. Recesses 181a and 181b may be in contact with each other, or they may have a plane between them.

[0407] Furthermore, in Figures 15(A) and 15(C), the top shape of the recess is shown as a hexagon (Figure 15(C)) and the cross-sectional shape as a semicircle (Figure 15(A)), but other shapes may be used as needed. For example, the top shape of the recess may be a triangle, a quadrilateral (including rectangles and squares), a pentagon or other polygon, a polygon with rounded corners, an ellipse, or a circle.

[0408] As the organic resin layer 180, an insulating layer having an organic material can be used. For example, as the organic resin layer 180, acrylic resin, polyimide resin, epoxy resin, imide resin, polyamide resin, polyimidoamide resin, silicone resin, siloxane resin, benzocyclobutene resin, phenol resin, and precursors of these resins can be used. Alternatively, as the organic resin layer 180, organic materials such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or alcohol-soluble polyamide resin may be used.

[0409] Furthermore, a photosensitive resin can be used as the organic resin layer 180. A photoresist may be used as the photosensitive resin. The photosensitive resin can be a positive-type material or a negative-type material.

[0410] The organic resin layer 180 may contain a material that absorbs visible light. For example, the organic resin layer 180 itself may be composed of a material that absorbs visible light, or the organic resin layer 180 may contain a pigment that absorbs visible light. As the organic resin layer 180, for example, a resin that can be used as a color filter that transmits red, blue, or green light and absorbs other light, or a resin that contains carbon black as a pigment and functions as a black matrix can be used.

[0411] Furthermore, the organic resin layer 180 has a first electrode 101 (first electrode 101R and first electrode 101W), and the first electrode 101 has an organic compound layer 103. The ends of the first electrode 101 and the organic compound layer 103 may be covered with an insulating layer 127.

[0412] Furthermore, the first electrode 101, formed on the organic resin layer 180, similarly has recesses along with the recesses of the organic resin layer 180. Additionally, the organic compound layer 103, formed on the first electrode 101, similarly has recesses along with the recesses of the first electrode 101. Furthermore, the common layer 104, formed on the organic compound layer 103, similarly has recesses along with the recesses of the organic compound layer 103. Furthermore, the common electrode 155, formed on the common layer 104, similarly has recesses along with the recesses of the common layer 104. In other words, the recesses of the organic resin layer 180, the first electrode 101, the organic compound layer 103, the common layer 104, and the common electrode 155 have a structure in which they overlap each other.

[0413] Furthermore, a common layer 104 is provided on the organic compound layer 103 and the insulating layer 127, and a common electrode 155 is provided on the common layer 104. A protective layer 135 is provided on the common electrode 155, and the structure is bonded to the substrate 352 via an adhesive layer 142.

[0414] Although Figure 15 does not show the light-emitting devices 130G and 130B, they are also provided.

[0415] [Display device 100E] The display device 100E shown in Figure 16(A) is a modified example of the top-emission type display device 100B shown in Figure 13(A), and differs from the display device 100B mainly in that it has a colored layer 136R, a colored layer 136G, and a colored layer 136B.

[0416] In the display device 100E, the light-emitting device 130 has a region that overlaps with one of the colored layers 136R, 136G, and 136B. The colored layers 136R, 136G, and 136B can be provided on the substrate 351 side of the substrate 352. The edges of the colored layer 136R, the edges of the colored layer 136G, and the edges of the colored layer 136B can overlap with the light-shielding layer 157.

[0417] In the display device 100E, the light-emitting device 130 can emit, for example, white light. Furthermore, for example, the colored layer 136R can transmit red light, the colored layer 136G can transmit green light, and the colored layer 136B can transmit blue light. The display device 100E may also be configured with the colored layers 136R, 136G, and 136B placed between the protective layer 135 and the adhesive layer 142.

[0418] Figures 13(A) and 16(A), etc., show examples in which the upper surface of layer 128 has a flat portion, but the shape of layer 128 is not particularly limited. Figures 16(B) to 16(D) show modified examples of layer 128.

[0419] As shown in Figures 16(B) and 16(D), the upper surface of layer 128 can have a shape that is concave in the center and its vicinity when viewed in cross-section, that is, a concave curved surface. Alternatively, a common layer 154 may be provided so as to be in contact with the common electrode 155.

[0420] Furthermore, as shown in Figure 16(C), the upper surface of layer 128 can be configured to have a shape that bulges in the center and its vicinity in a cross-sectional view, that is, a shape with a convex curved surface.

[0421] Furthermore, the upper surface of layer 128 may have one or both of a convex and a concave surface. Also, the number of convex and concave surfaces on the upper surface of layer 128 is not limited and can be one or more.

[0422] Furthermore, the height of the top surface of layer 128 and the height of the top surface of conductive layer 224R may be the same, approximately the same, or different from each other. For example, the height of the top surface of layer 128 may be lower or higher than the height of the top surface of conductive layer 224R.

[0423] Furthermore, Figure 16(B) can be seen as an example in which layer 128 is housed inside a recess formed in the conductive layer 224R. On the other hand, as shown in Figure 16(D), layer 128 may exist outside the recess formed in the conductive layer 224R, that is, the width of the upper surface of layer 128 may be wider than that of the recess.

[0424] [Display device 100F] The display device 100F shown in Figure 17(A) is a modified example of the top-emission type display device 100B shown in Figure 13, and has a microlens 182 on the colored layer 136R, colored layer 136G, and colored layer 136B. Note that in the figure, the reference numerals for components that are the same as in Figure 13 may be omitted, and details should be referred to in Figure 13.

[0425] Furthermore, Figure 17(B) shows the top view layout of pixel 178 (pixels 178a and 178b) having sub-pixels 110 (sub-pixels 110R, 110G, and 110B), and Figure 17(C) shows the top view of the microlens 182 in the region where sub-pixels 110R, 110G, and 110B of pixel 178 are formed. The region where the common electrode 155 and the organic compound layer 103 are in contact is the width 110Gw of the light-emitting region of sub-pixel 110G.

[0426] The display device 100F shown in Figure 15(A) has a planarization film 143 on a protective layer 135, and a colored layer 136R, a colored layer 136G, and a colored layer 136B on the planarization film 144. The planarization film 144 is provided so as to cover the colored layers 136R, 136G, and 136B. A microlens 182 is provided on the planarization film 144.

[0427] Furthermore, as shown in Figure 17(C), the microlenses 182 may be provided for each sub-pixel in the region where the sub-pixels are formed.

[0428] In Figure 17(C), the top surface shape of the microlens 182 is shown as a hexagon, but other shapes may be used as needed. For example, the top surface shape of the microlens 182 may be a triangle, a quadrilateral (including rectangles and squares), a pentagon, or other polygons, a polygon with rounded corners, an ellipse, or a circle.

[0429] The microlens 182 can be formed using the same material as the organic resin layer 180.

[0430] This embodiment can be appropriately combined with other embodiments or examples. Furthermore, if multiple configuration examples are shown within a single embodiment in this specification, these configuration examples can be appropriately combined.

[0431] (Embodiment 6) This embodiment describes an electronic device according to one aspect of the present invention.

[0432] The electronic device of this embodiment has a light-emitting device according to one aspect of the present invention in its display unit. The light-emitting device according to one aspect of the present invention is highly reliable and easily capable of high-definition and high-resolution displays. Therefore, it can be used in the display units of various electronic devices.

[0433] Examples of electronic devices include television sets, desktop or notebook personal computers, computer monitors, digital signage, large game machines such as pachinko machines, and other electronic devices with relatively large screens, as well as digital cameras, digital video cameras, digital photo frames, mobile phones, portable game consoles, personal digital assistants, and audio playback devices.

[0434] In particular, since the light-emitting device according to one aspect of the present invention can increase resolution, it can be suitably used in electronic devices having a relatively small display area. Examples of such electronic devices include wristwatch-type and bracelet-type information terminals (wearable devices), as well as wearable devices that can be worn on the head, such as VR devices such as head-mounted displays, AR devices such as glasses, and MR devices.

[0435] A light-emitting 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), 4K (3840 x 2160 pixels), or 8K (7680 x 4320 pixels). In particular, a resolution of 4K, 8K, or higher is preferred. Furthermore, the pixel density (resolution) of the light-emitting device according to one aspect of the present invention is preferably 100 ppi or more, 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 a light-emitting device having high resolution and / or high detail, it is possible to further enhance the sense of presence and depth. Furthermore, there are no particular limitations on the aspect ratio of the light-emitting device according to one embodiment of the present invention. For example, the light-emitting device can support various aspect ratios such as 1:1 (square), 4:3, 16:9, and 16:10.

[0436] The electronic device of this embodiment may have sensors (including those with functions to measure 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).

[0437] 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.

[0438] Figures 18(A) to 18(D) illustrate an example of a wearable device that can be worn on the head. These wearable devices have at least one of the following functions: a function to display AR content, a function to display VR content, a function to display SR content, and a function to display MR content. By having an electronic device that has the function to display at least one of the following content types, such as AR, VR, SR, and MR, it is possible to enhance the user's sense of immersion.

[0439] The electronic device 700A shown in Figure 18(A) and the electronic device 700B shown in Figure 18(B) each include a pair of display panels 751, a pair of housings 721, a communication unit (not shown), a pair of mounting units 723, a control unit (not shown), an imaging unit (not shown), a pair of optical members 753, a frame 757, and a pair of nose pads 758.

[0440] A light-emitting device according to one embodiment of the present invention can be applied to the display panel 751. Therefore, a highly reliable electronic device can be made.

[0441] Electronic devices 700A and 700B can project an image displayed on the display panel 751 onto the display area 756 of the optical element 753. Because the optical element 753 is translucent, the user can see the image displayed on the display area superimposed on the transmitted image visible through the optical element 753. Therefore, electronic devices 700A and 700B are electronic devices capable of AR display.

[0442] Electronic devices 700A and 700B may be equipped with cameras capable of capturing images of the area in front of them as imaging units. Furthermore, electronic devices 700A and 700B may each be equipped with acceleration sensors such as gyro sensors to detect the orientation of the user's head and display an image corresponding to that orientation in the display area 756.

[0443] The communications unit has a wireless communication device, which can supply, for example, a video signal. Alternatively, instead of the wireless communication device, or in addition to the wireless communication device, it may be equipped with a connector to which a cable supplying video signals and power potential can be connected.

[0444] Furthermore, electronic devices 700A and 700B are equipped with batteries that can be charged wirelessly, wired, or both.

[0445] The housing 721 may be equipped with a touch sensor module. The touch sensor module has the function of detecting when the outer surface of the housing 721 is touched. The touch sensor module can detect the user's tap or slide operations and perform various processes. For example, a tap operation can be used to pause or resume the video, and a slide operation can be used to fast forward or rewind. Furthermore, by providing a touch sensor module in each of the two housings 721, the range of operations can be expanded.

[0446] Various types of touch sensors can be used in the touch sensor module. For example, various methods such as capacitive, resistive, infrared, electromagnetic induction, surface acoustic wave, or optical sensors can be employed. In particular, it is preferable to apply capacitive or optical sensors to the touch sensor module.

[0447] When using an optical touch sensor, a photoelectric conversion device (also called a photoelectric conversion element) can be used as the light-receiving element. The active layer of the photoelectric conversion device can be made of either an inorganic semiconductor or an organic semiconductor, or both.

[0448] The electronic device 800A shown in Figure 18(C) and the electronic device 800B shown in Figure 18(D) each include a pair of display units 820, a housing 821, a communication unit 822, a pair of mounting units 823, a control unit 824, a pair of imaging units 825, and a pair of lenses 832.

[0449] A light-emitting device according to one embodiment of the present invention can be applied to the display unit 820. Therefore, a highly reliable electronic device can be made.

[0450] The display unit 820 is located inside the housing 821, in a position where it can be seen through the lens 832. Furthermore, by displaying different images on a pair of display units 820, a three-dimensional display using parallax can also be performed.

[0451] Electronic devices 800A and 800B can be described as electronic devices for VR. A user wearing electronic device 800A or electronic device 800B can view the image displayed on the display unit 820 through the lens 832.

[0452] It is preferable that electronic devices 800A and 800B each have a mechanism that allows adjustment of the left and right positions of the lens 832 and the display unit 820 so that they are in the optimal position according to the user's eye position. It is also preferable that they have a mechanism that adjusts the focus by changing the distance between the lens 832 and the display unit 820.

[0453] The attachment portion 823 allows the user to attach the electronic device 800A or 800B to their head. Note that, for example, in Figure 18(C), it is illustrated as having a shape similar to the temples (joints, or arms, etc.) of eyeglasses, but it is not limited to this. The attachment portion 823 only needs to be wearable by the user; for example, it may be in the shape of a helmet or a band.

[0454] The imaging unit 825 has the function of acquiring external information. The data acquired by the imaging unit 825 can be output to the display unit 820. An image sensor can be used in the imaging unit 825. In addition, multiple cameras may be provided to accommodate multiple angles of view, such as telephoto and wide-angle.

[0455] Although an example with an imaging unit 825 is shown here, any distance measuring sensor (hereinafter also referred to as a detection unit) capable of measuring the distance to an object can be provided. In other words, the imaging unit 825 is one form of a detection unit. As the detection unit, for example, an image sensor or a distance image sensor such as LiDAR (Light Detection and Ranging) can be used. By using the image obtained by the camera and the image obtained by the distance image sensor, more information can be acquired, enabling more accurate gesture control.

[0456] The electronic device 800A may have a vibration mechanism that functions as a bone conduction earphone. For example, a configuration having such a vibration mechanism can be applied to one or more of the display unit 820, housing 821, and mounting unit 823. This allows users to enjoy video and audio simply by wearing the electronic device 800A, without needing separate audio equipment such as headphones, earphones, or speakers.

[0457] Electronic devices 800A and 800B may each have input terminals. Cables can be connected to the input terminals to supply video signals from video output devices, etc., and power for charging batteries provided within the electronic devices.

[0458] An electronic device according to one aspect of the present invention may have a function for wireless communication with an earphone 750. The earphone 750 has a communication unit (not shown) and has a wireless communication function. The earphone 750 can receive information (e.g., voice data) from the electronic device through its wireless communication function. For example, the electronic device 700A shown in Figure 18(A) has a function for transmitting information to the earphone 750 through its wireless communication function. Also, for example, the electronic device 800A shown in Figure 18(C) has a function for transmitting information to the earphone 750 through its wireless communication function.

[0459] Furthermore, the electronic device may have an earphone section. The electronic device 700B shown in Figure 18(B) has an earphone section 727. For example, the earphone section 727 and the control unit can be connected to each other by a wire. Part of the wiring connecting the earphone section 727 and the control unit may be located inside the housing 721 or the mounting section 723.

[0460] Similarly, the electronic device 800B shown in Figure 18(D) has an earphone unit 827. For example, the earphone unit 827 and the control unit 824 can be connected to each other by wire. Part of the wiring connecting the earphone unit 827 and the control unit 824 may be located inside the housing 821 or the mounting unit 823. Also, the earphone unit 827 and the mounting unit 823 may have magnets. This allows the earphone unit 827 to be fixed to the mounting unit 823 by magnetic force, which is preferable as it facilitates storage.

[0461] Furthermore, the electronic device may have an audio output terminal to which earphones or headphones can be connected. The electronic device may also have an audio input terminal and / or an audio input mechanism. For example, a microphone or other sound-collecting device can be used as the audio input mechanism. By having an audio input mechanism, the electronic device may be given the function of a so-called headset.

[0462] Thus, as one embodiment of the present invention, both eyeglass-type (electronic devices 700A and 700B, etc.) and goggle-type (electronic devices 800A and 800B, etc.) are preferred as electronic devices.

[0463] Furthermore, an electronic device according to one aspect of the present invention can transmit information to earphones via wired or wireless means.

[0464] The electronic device 6500 shown in Figure 19(A) is a portable information terminal that can be used as a smartphone.

[0465] 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.

[0466] A light-emitting device according to one embodiment of the present invention can be applied to the display unit 6502. Therefore, a highly reliable electronic device can be made.

[0467] Figure 19(B) is a schematic cross-sectional view of the housing 6501 including the end on the microphone 6506 side.

[0468] 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, and battery 6518 are arranged in the space enclosed by the housing 6501 and the protective member 6510.

[0469] 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).

[0470] 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.

[0471] A light-emitting device according to one embodiment of the present invention can be applied to the display panel 6511. This makes it possible to realize an extremely lightweight electronic device. Furthermore, because the display panel 6511 is extremely thin, it is possible to incorporate a large-capacity battery 6518 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 section, an electronic device with a narrow bezel can be realized.

[0472] Figure 19(C) shows an example of a television system. The television system 7100 has a display unit 7000 incorporated into a housing 7171. Here, the housing 7171 is shown supported by a stand 7173.

[0473] A light-emitting device according to one embodiment of the present invention can be applied to the display unit 7000. Therefore, a highly reliable electronic device can be made.

[0474] The television device 7100 shown in Figure 19(C) can be operated using the operation switches on the housing 7171 and a separate remote control unit 7151. 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 7151 may have a display unit that displays information output from the remote control unit 7151. 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 7151.

[0475] 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.

[0476] Figure 19(D) shows an example of a notebook personal computer. The notebook personal computer 7200 has a casing 7211, a keyboard 7212, a pointing device 7213, and an external connection port 7214, etc. A display unit 7000 is incorporated into the casing 7211.

[0477] A light-emitting device according to one embodiment of the present invention can be applied to the display unit 7000. Therefore, a highly reliable electronic device can be made.

[0478] Figures 19(E) and 19(F) show examples of digital signage that can be used in shop windows and display cases.

[0479] The digital signage 7300 shown in Figure 19(E) 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.

[0480] Figure 19(F) 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.

[0481] In Figures 19(E) and 19(F), a light-emitting device according to one embodiment of the present invention can be applied to the display unit 7000. Therefore, a highly reliable electronic device can be made.

[0482] 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.

[0483] In particular, when using a display device according to one aspect of the present invention for advertising using the digital signage 7300 and digital signage 7400 shown in Figures 19(E) and 19(F), the degree of freedom of expression can be increased by using a light-transmitting panel. For example, a light-transmitting display device can be manufactured by using wiring and support members made of a conductive film that transmits visible light and adjusting the distance between pixel electrodes.

[0484] Furthermore, by using a light-emitting device according to one aspect of the present invention, in addition to the wiring and support members using the conductive film that transmits visible light, it is possible to increase the brightness per pixel. In other words, good display is possible even with a small aperture ratio of the display device, thus increasing the light transmittance of the display section of the display device. Therefore, such a configuration is suitable as a light-transmitting display device according to one aspect of the present invention.

[0485] Furthermore, as shown in Figures 19(E) and 19(F), 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.

[0486] 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 an unspecified number of users to participate in and enjoy the game simultaneously.

[0487] The electronic equipment shown in Figures 20(A) to 20(G) 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 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.

[0488] The electronic devices shown in Figures 20(A) to 20(G) 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.

[0489] The details of the electronic equipment shown in Figures 20(A) to 20(G) will be explained below.

[0490] Figure 20(A) is a perspective view showing a personal digital information terminal (PDI) 9171. The PDI 9171 can be used, for example, as a smartphone. The PDI 9171 may also be equipped with a speaker 9003, a connection terminal 9006, or a sensor 9007. Furthermore, the PDI 9171 can display text and image information on multiple surfaces. Figure 20(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, phone calls, etc., the subject of emails or SNS messages, the sender's name, date and time, time, battery level, signal strength, etc. Alternatively, icons 9050, etc., may be displayed in the position where the information 9051 is displayed.

[0491] Figure 20(B) is a perspective view showing the personal digital assistant (PDA) 9172. The PDA 9172 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 9172, while the PDA 9172 is stored in the breast pocket of their clothing. The user can check the display without taking the PDA 9172 out of their pocket and decide, for example, whether or not to answer a call.

[0492] Figure 20(C) is a perspective view showing the tablet terminal 9173. The tablet terminal 9173 can run various applications, such as mobile phone calls, email, document viewing and creation, music playback, internet communication, and computer games. The tablet terminal 9173 has a display unit 9001, a camera 9002, a microphone 9008, and a speaker 9003 on the front of the housing 9000. Operation keys 9005 are located on the left side of the housing 9000 as buttons for operation, and connection terminals 9006 are located on the bottom.

[0493] Figure 20(D) 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 personal information terminal 9200 may have an operation key 9005 as an operation button on the left side of the housing 9000 and a sensor 9007 on the bottom. As an example, a curved bangle-type housing 9000 is shown, but the housing 9000 may be structured to allow attachment of a belt or the like. The display unit 9001 has a curved display surface and can display along the curved surface. The power storage device 9004 may also have a curved shape that follows the housing 9000. The power storage device 9004 is also flexible and can be bent according to the change in shape when attached or detached. It may also have a charging control IC connected to the power storage device 9004. The personal information terminal 9200 can also make hands-free calls by communicating with, for example, a wireless communication headset. Furthermore, the portable information terminal 9200 can wirelessly transmit data to and from other information terminals, and can also be charged wirelessly. Alternatively, data transmission and charging may be performed via wired connections using a connection terminal 9006 provided on the housing 9000.

[0494] Figures 20(E) to 20(G) are perspective views showing a foldable portable information terminal 9201. Figure 20(E) shows the portable information terminal 9201 in an unfolded state, Figure 20(G) shows it in a folded state, and Figure 20(F) shows a state in between, transitioning from one of Figures 20(E) or 20(G) to the other. 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.

[0495] This embodiment can be appropriately combined with other embodiments or examples. Furthermore, if multiple configuration examples are shown within a single embodiment in this specification, these configuration examples can be appropriately combined.

[0496] (Embodiment 7) This embodiment describes a light-emitting device using the organic EL elements described in Embodiment 1 and Embodiment 2.

[0497] In this embodiment, a light-emitting device fabricated using the organic EL elements described in Embodiment 1 and Embodiment 2 will be explained with reference to Figure 21. Figure 21(A) is a top view showing the light-emitting device, and Figure 21(B) is a cross-sectional view obtained by cutting Figure 21(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 organic EL elements. 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.

[0498] 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 609, which serves as an external input terminal. Although only the FPC is shown in the 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.

[0499] Next, the cross-sectional structure will be explained using Figure 21(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.

[0500] 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.

[0501] 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.

[0502] 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.

[0503] 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.

[0504] 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).

[0505] 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.

[0506] By using such materials as semiconductor layers, fluctuations in electrical properties can be suppressed, enabling the realization of highly reliable transistors.

[0507] 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.

[0508] 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 multiple layers. The undercoat can be formed using sputtering, CVD (plasma CVD, thermal CVD, MOCVD (Metal Organic CVD), etc.), ALD, coating, printing, etc. However, the undercoat may be omitted if it is not necessary.

[0509] Note that FET623 is one of the transistors formed in the source line drive circuit 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.

[0510] 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.

[0511] 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.

[0512] 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.

[0513] 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.

[0514] Furthermore, the EL layer 616 is formed by various methods such as deposition using a deposition mask, inkjet method, and spin coating method. The EL layer 616 includes the configuration described in Embodiment 1 and Embodiment 2. When the EL layer 616 is formed from the first electrode 613 side, if the first electrode 613 is the anode, the first hole transport layer 112_1 and the second hole transport layer 112_2 are deposited in that order, resulting in the order of anode, first hole transport layer 112_1, second hole transport layer 112_2, and cathode from the substrate side. In addition, other materials constituting the EL layer 616 may be low molecular weight compounds or high molecular weight compounds (including oligomers and dendrimers).

[0515] 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 transpar...

Claims

1. It comprises a first electrode, a second electrode, a light-emitting layer, a first hole transport layer, and a first electron transport layer. The first electrode is formed on a substrate and is located between the second electrode and the substrate. The light-emitting layer, the first hole transport layer, and the first electron transport layer are located between the first electrode and the second electrode. The light-emitting layer is located between the first hole transport layer and the first electron transport layer. The light-emitting layer and the first hole transport layer are in contact with each other. A light-emitting device in which the GSP_slope (mV / nm) of the layer located on the second electrode side of the light-emitting layer and the first hole transport layer is smaller than the GSP_slope (mV / nm) of the layer located on the first electrode side (where GSP_slope (mV / nm) is expressed as ΔV / Δd when the change in surface potential ΔV (mV) is equal to the change in film thickness Δd (nm)).

2. It comprises a first electrode, a second electrode, a light-emitting layer, a first hole transport layer, and a first electron transport layer. The first electrode is formed on a substrate and is located between the second electrode and the substrate. The light-emitting layer, the first hole transport layer, and the first electron transport layer are located between the first electrode and the second electrode. The light-emitting layer is located between the first hole transport layer and the first electron transport layer. A light-emitting device in which the GSP_slope (mV / nm) of the layer located on the first electrode side of the light-emitting layer and the first electron transport layer is smaller than the GSP_slope (mV / nm) of the layer located on the second electrode side (where GSP_slope (mV / nm) is expressed as ΔV / Δd when the change in surface potential ΔV (mV) is equal to the change in film thickness Δd (nm)).

3. In claim 2, A light-emitting device in which the GSP_slope (mV / nm) of the layer located on the second electrode side of the light-emitting layer and the first hole transport layer is smaller than the GSP_slope (mV / nm) of the layer located on the first electrode side.

4. In any one of claims 1 to 3, It has a second hole transport layer and a second electron transport layer, The second hole transport layer and the second electron transport layer are located between the first electrode and the second electrode. The first hole transport layer is located between the second hole transport layer and the light-emitting layer. The first electron transport layer is located between the second electron transport layer and the light-emitting layer. Of the first hole transport layer and the second hole transport layer, the GSP_slope (mV / nm) of the layer located on the second electrode side is greater than the GSP_slope (mV / nm) of the layer located on the first electrode side. A light-emitting device wherein, of the first electron transport layer and the second electron transport layer, the GSP_slope (mV / nm) of the layer located on the first electrode side is greater than the GSP_slope (mV / nm) of the layer located on the second electrode side.

5. In claim 1 or claim 3, A light-emitting device in which the difference between the GSP_slope (mV / nm) of the light-emitting layer and the GSP_slope (mV / nm) of the first hole transport layer is 0 mV / nm or more and 20 mV / nm or less.

6. In claim 2 or claim 3, A light-emitting device in which the difference between the GSP_slope (mV / nm) of the light-emitting layer and the GSP_slope (mV / nm) of the first electron transport layer is 0 mV / nm or more and 20 mV / nm or less.

7. In claim 3, A light-emitting device in which the difference between the GSP_slope (mV / nm) of the first hole transport layer and the GSP_slope (mV / nm) of the first electron transport layer is 0 mV / nm or more and 20 mV / nm or less.

8. In any one of claims 1 to 3, A light-emitting device wherein, at the peak wavelength of the electroluminescence spectrum of the light-emitting device, the refractive index of at least one of the first hole transport layer and the first electron transport layer is 1.75 or less.

9. In claim 4, A light-emitting device wherein, at the peak wavelength of the electroluminescence spectrum of the light-emitting device, the refractive index of at least one of the second hole transport layer and the second electron transport layer is 1.75 or less.

10. It comprises a first electrode, a second electrode, a light-emitting layer, a first hole transport layer, and a first electron transport layer. The first electrode is formed on a substrate and is located between the second electrode and the substrate. The light-emitting layer, the first hole transport layer, and the first electron transport layer are located between the first electrode and the second electrode. The first hole transport layer is located between the first electrode and the light-emitting layer. The first electron transport layer is located between the second electrode and the light-emitting layer. The light-emitting layer and the first hole transport layer are in contact with each other. The light-emitting layer comprises a host material and a light-emitting substance. The first hole transport layer has a first organic compound, The first electron transport layer has a second organic compound, A light-emitting device in which the GSP_slope (mV / nm) of the deposited film of the host material is smaller than the GSP_slope (mV / nm) of the deposited film of the first organic compound (where GSP_slope (mV / nm) is expressed as ΔV / Δd when the change in surface potential ΔV (mV) is equal to the change in film thickness Δd (nm)).

11. It comprises a first electrode, a second electrode, a light-emitting layer, a first hole transport layer, and a first electron transport layer. The first electrode is formed on a substrate and is located between the second electrode and the substrate. The light-emitting layer, the first hole transport layer, and the first electron transport layer are located between the first electrode and the second electrode. The first hole transport layer is located between the first electrode and the light-emitting layer. The first electron transport layer is located between the second electrode and the light-emitting layer. The light-emitting layer comprises a host material and a light-emitting substance. The first hole transport layer has a first organic compound, The first electron transport layer has a second organic compound, A light-emitting device in which the GSP_slope (mV / nm) of the deposited film of the host material is smaller than the GSP_slope (mV / nm) of the deposited film of the second organic compound (where GSP_slope (mV / nm) is expressed as ΔV / Δd when the change in surface potential ΔV (mV) is equal to the change in film thickness Δd (nm)).

12. In claim 11, A light-emitting device in which the GSP_slope (mV / nm) of the deposited film of the host material is smaller than the GSP_slope (mV / nm) of the deposited film of the first organic compound.

13. In claim 10 or claim 12, It has a second hole transport layer and a second electron transport layer, The second hole transport layer and the second electron transport layer are located between the first electrode and the second electrode. The first hole transport layer is located between the second hole transport layer and the light-emitting layer. The first electron transport layer is located between the second electron transport layer and the light-emitting layer. The second hole transport layer has a third organic compound, The second electron transport layer has a fourth organic compound, The GSP_slope (mV / nm) of the vapor-deposited film of the first organic compound is greater than the GSP_slope (mV / nm) of the vapor-deposited film of the third organic compound. A light-emitting device in which the GSP_slope (mV / nm) of the vapor-deposited film of the second organic compound is greater than the GSP_slope (mV / nm) of the vapor-deposited film of the fourth organic compound.

14. In claim 10 or claim 12, A light-emitting device in which the difference between the GSP_slope (mV / nm) of the deposited film of the host material and the GSP_slope (mV / nm) of the deposited film of the first organic compound is 0 mV / nm or more and 20 mV / nm or less.

15. In claim 11 or claim 12, A light-emitting device in which the difference between the GSP_slope (mV / nm) of the vapor-deposited film of the host material and the GSP_slope (mV / nm) of the vapor-deposited film of the second organic compound is 0 mV / nm or more and 20 mV / nm or less.

16. In claim 13, A light-emitting device in which the difference between the GSP_slope (mV / nm) of the vapor-deposited film of the first organic compound and the GSP_slope (mV / nm) of the vapor-deposited film of the second organic compound is 0 mV / nm or more and 20 mV / nm or less.

17. In any one of claims 10 to 12, A light-emitting device wherein, at the peak wavelength of the electroluminescence spectrum of the light-emitting device, at least one of the refractive index of the first organic compound film and the refractive index of the second organic compound film is 1.75 or less.

18. In any one of claims 10 to 12, A light-emitting device in which at least one of the first organic compound and the second organic compound is an organic compound having at least one group selected from a chain alkyl group having 2 to 10 carbon atoms and a cycloalkyl group having 6 to 12 carbon atoms.

19. In claim 13, A light-emitting device wherein, at the peak wavelength of the electroluminescence spectrum of the light-emitting device, the refractive index of the film of the third organic compound is 1.75 or less.

20. In claim 13, A light-emitting device in which at least one of the third organic compound and the fourth organic compound is an organic compound having at least one group selected from a chain alkyl group having 2 to 10 carbon atoms and a cycloalkyl group having 6 to 12 carbon atoms.

21. In any one of claims 10 to 12, The light-emitting material is a fluorescent light-emitting material, and the device is a light-emitting device.

22. In any one of claims 10 to 12, The energy difference between the HOMO level of the host material and the HOMO level of the luminescent material is 0.25 eV or greater. A light-emitting device wherein the concentration of the light-emitting material in the light-emitting layer is 0.5 wt% or more and 25 wt% or less relative to the host material.

Images