Light emitting device

Abstract

To provide a light-emitting device with low driving voltage.SOLUTION: A first electrode, a second electrode, a light-emitting layer, a first layer, and a second layer, wherein the first electrode is formed on a substrate and located between the second electrode and the substrate, and the light-emitting layer is located between the first electrode and the second electrode; The first layer is positioned between the first electrode and the light-emitting layer, the second layer is positioned between the second electrode and the light-emitting layer, one of the first electrode and the second electrode is an anode, the other is a cathode, and GSP _ slope (mV / nm) of one of the light-emitting layer and the first layer which is positioned on the cathode side is higher than GSP _ slope (mV / nm) of the other of the light-emitting layer and the first layer which is positioned on the anode side. In the light-emitting device, GSP _ slope (mV / nm) of one of the light-emitting layer and the second layer which is positioned on the anode side is higher than GSP _ slope (mV / nm) of the other of the light-emitting layer and the second layer which is positioned on the cathode side. Here, GSP _ slope (mV / nm) is a parameter represented by Δ V / Δ d when the amount of change in the surface potential is Δ V (mV) with respect to the amount of change in the film thickness Δ d (nm).SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

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

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

[0004] Furthermore, these organic EL devices can emit light in a planar, continuous manner, making it possible to achieve a surface-like emission. This is a feature that is difficult to achieve with point light sources such as incandescent bulbs and LEDs, or linear light sources such as fluorescent lamps, making them highly useful as surface light sources for lighting applications.

[0005] Displays and lighting devices using organic EL elements are suitable for a variety of electronic devices, but research and development is ongoing to find organic EL elements with better characteristics (see, for example, Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] Yutaka Noguchi and two others, "Orientational Polarization Phenomena of Polar Molecules and Interfacial Properties of Organic Thin Film Devices," Journal of the Vacuum Society of Japan, 2015, Vol. 58, No. 3 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of one embodiment of the present invention is to provide a light-emitting device with low driving voltage, a light-emitting device with high emission efficiency, or a light-emitting device, electronic device, or display device with low power consumption.

[0008] Note that the description of these problems does not preclude the existence of other problems. Note that one embodiment of the present invention does not necessarily solve all of these problems. Note that problems other than these will become apparent from the description of the specification, drawings, claims, etc., and it is possible to extract other problems from the description of the specification, drawings, claims, etc. [Means for solving the problem]

[0009] One aspect of the present invention is to select organic compounds to be used in each layer of an organic compound layer so that, in an organic compound layer of a forward-stacked light-emitting device, the GSP_slope (mV / nm), which is a parameter representing the magnitude of the giant surface potential (GSP) of the light-emitting layer, is larger than that of the carrier transport layers sandwiching the light-emitting layer, and in an organic compound layer of an inverse-stacked light-emitting device, the GSP_slope (mV / nm) of the light-emitting layer is smaller than that of the carrier transport layers sandwiching the light-emitting layer, thereby enabling an electric field to be applied effectively to the light-emitting layer.

[0010] That is, one embodiment of the present invention is a light-emitting device having a first electrode, a second electrode, an emitting layer, a first layer, and a second layer, wherein the first electrode is formed on a substrate and is located between the second electrode and the substrate, the emitting layer is located between the first electrode and the second electrode, the first layer is located between the first electrode and the emitting layer, and the second layer is located between the second electrode and the emitting layer, one of the first electrode and the second electrode is an anode and the other is a cathode, and the GSP_slope (mV / nm) of the layer of the emitting layer and the first layer located closer to the cathode is larger than the GSP_slope (mV / nm) of the layer of the emitting layer and the second layer located closer to the anode, and the GSP_slope (mV / nm) of the layer of the emitting layer and the second layer located closer to the anode is larger than the GSP_slope (mV / nm) of the layer of the emitting layer and the second layer located closer to the cathode. Here, GSP_slope (mV / nm) is a parameter expressed as ΔV / Δd when the amount of change in surface potential is ΔV (mV) relative to the amount of change in film thickness Δd (nm).

[0011] One embodiment of the present invention is a light-emitting device having a first electrode, a second electrode, an emitting layer, a first layer, and a second layer, wherein the first electrode is electrically connected to a transistor, the emitting layer is located between the first electrode and the second electrode, the first layer is located between the first electrode and the emitting layer, and the second layer is located between the second electrode and the emitting layer, one of the first electrode and the second electrode is an anode and the other is a cathode, and the GSP_slope (mV / nm) of the layer of the emitting layer and the first layer located closer to the cathode is larger than the GSP_slope (mV / nm) of the layer of the emitting layer and the second layer located closer to the anode, and the GSP_slope (mV / nm) of the layer of the emitting layer and the second layer located closer to the anode is larger than the GSP_slope (mV / nm) of the layer of the emitting layer and the second layer located closer to the cathode. Here, GSP_slope (mV / nm) is a parameter expressed as ΔV / Δd when the amount of change in surface potential is ΔV (mV) relative to the amount of change in film thickness Δd (nm).

[0012] One embodiment of the present invention is a light-emitting device having a first electrode, a second electrode, an emitting layer, a first layer, and a second layer, wherein the first electrode is partially covered with an insulator, the emitting layer is located between the first electrode and the second electrode, the first layer is located between the first electrode and the emitting layer, and the second layer is located between the second electrode and the emitting layer, one of the first electrode and the second electrode is an anode and the other is a cathode, and the GSP_slope (mV / nm) of the layer of the emitting layer and the first layer located closer to the cathode is greater than the GSP_slope (mV / nm) of the layer of the emitting layer and the second layer located closer to the anode, and the GSP_slope (mV / nm) of the layer of the emitting layer and the second layer located closer to the anode is greater than the GSP_slope (mV / nm) of the layer of the emitting layer and the second layer located closer to the cathode. Here, GSP_slope (mV / nm) is a parameter expressed as ΔV / Δd when the amount of change in surface potential is ΔV (mV) relative to the amount of change in film thickness Δd (nm).

[0013] One embodiment of the present invention is a light-emitting device having a first electrode, a second electrode, an emitting layer, a first layer, and a second layer, wherein the first electrode is formed on an insulating film and is located between the second electrode and the insulating film, an external connection electrode is provided on the insulating film, the emitting layer is located between the first electrode and the second electrode, the first layer is located between the first electrode and the emitting layer, and the second layer is located between the second electrode and the emitting layer, one of the first electrode and the second electrode is an anode and the other is a cathode, and the GSP_slope (mV / nm) of the layer of the emitting layer and the first layer located closer to the cathode is larger than the GSP_slope (mV / nm) of the layer of the emitting layer and the second layer located closer to the anode, and the GSP_slope (mV / nm) of the layer of the emitting layer and the second layer located closer to the anode is larger than the GSP_slope (mV / nm) of the layer of the emitting layer and the second layer located closer to the cathode. Here, GSP_slope (mV / nm) is a parameter expressed as ΔV / Δd when the amount of change in surface potential is ΔV (mV) relative to the amount of change in film thickness Δd (nm).

[0014] Another embodiment of the present invention is a light-emitting device having any of the above structures, which includes a third layer and a fourth layer, the third layer being located between the first layer and the first electrode, and the fourth layer being located between the second layer and the second electrode, and wherein the GSP_slope (mV / nm) of the layer of the first and third layers located on the cathode side is greater than the GSP_slope (mV / nm) of the layer of the second and fourth layers located on the anode side is greater than the GSP_slope (mV / nm) of the layer of the second and fourth layers located on the anode side.

[0015] Another embodiment of the present invention is a light-emitting device including a first electrode, a second electrode, a light-emitting layer, a first layer, and a second layer, wherein the first electrode is formed on a substrate and is located between the second electrode and the substrate, the light-emitting layer is located between the first electrode and the second electrode, the first layer is located between the first electrode and the light-emitting layer, the second layer is located between the second electrode and the light-emitting layer, the first electrode is an anode, the second electrode is a cathode, and the GSP_slope (mV / nm) of the light-emitting layer is larger than the GSP_slope (mV / nm) of the first layer, which is larger than the GSP_slope (mV / nm) of the second layer, where GSP_slope (mV / nm) is a parameter expressed as ΔV / Δd when the change in surface potential ΔV (mV) is relative to the change in film thickness Δd (nm). In this structure, the first electrode may be electrically connected to a transistor. In this structure, a portion of the first electrode may be covered with an insulator. In this structure, the first electrode may be formed on an insulating film. Another embodiment of the present invention is a light-emitting device having the above structure, which includes a third layer and a fourth layer, the third layer being located between the first layer and the first electrode, the fourth layer being located between the second layer and the second electrode, and the GSP_slope (mV / nm) of the first layer being larger than the GSP_slope (mV / nm) of the third layer, and the GSP_slope (mV / nm) of the second layer being larger than the GSP_slope (mV / nm) of the fourth layer.

[0016] Another embodiment of the present invention is a light-emitting device including a first electrode, a second electrode, a light-emitting layer, a first layer, and a second layer, wherein the first electrode is formed on a substrate and is located between the second electrode and the substrate, the light-emitting layer is located between the first electrode and the second electrode, the first layer is located between the first electrode and the light-emitting layer, the second layer is located between the second electrode and the light-emitting layer, the first electrode is a cathode, the second electrode is an anode, and the GSP_slope (mV / nm) of the first layer is larger than the GSP_slope (mV / nm) of the light-emitting layer, and the GSP_slope (mV / nm) of the second layer is larger than the GSP_slope (mV / nm) of the light-emitting layer, where GSP_slope (mV / nm) is a parameter expressed as ΔV / Δd when the change in surface potential ΔV (mV) is relative to the change in film thickness Δd (nm). In this structure, the first electrode may be electrically connected to a transistor. In this structure, a portion of the first electrode may be covered with an insulator. In this structure, the first electrode may be formed on an insulating film. Another embodiment of the present invention is a light-emitting device having the above structure, which includes a third layer and a fourth layer, the third layer being located between the first layer and the first electrode, the fourth layer being located between the second layer and the second electrode, and the GSP_slope (mV / nm) of the third layer being larger than the GSP_slope (mV / nm) of the first layer, and the GSP_slope (mV / nm) of the fourth layer being larger than the GSP_slope (mV / nm) of the second layer.

[0017] Another embodiment of the present invention is a light-emitting device having any of the above structures, wherein the refractive index of at least one of the first layer and the second layer is lower than the refractive index of the light-emitting layer at a peak wavelength of an electroluminescence spectrum of the light-emitting device.

[0018] Another embodiment of the present invention is a light-emitting device having any of the above structures, wherein the refractive index of at least one of the first layer and the second layer is 1.75 or less at the peak wavelength of the electroluminescence spectrum of the light-emitting device.

[0019] Another embodiment of the present invention is a light-emitting device having any of the above structures, wherein the refractive index of at least one of the first layer, the second layer, the third layer, and the fourth layer is lower than the refractive index of the light-emitting layer at a peak wavelength of an electroluminescence spectrum of the light-emitting device.

[0020] Another embodiment of the present invention is a light-emitting device having any of the above structures, wherein the refractive index of at least one of the first layer, the second layer, the third layer, and the fourth layer is 1.75 or less at the peak wavelength of the electroluminescence spectrum of the light-emitting device.

[0021] Another embodiment of the present invention provides a light-emitting device including a first electrode, a second electrode, a light-emitting layer, a first layer, and a second layer, wherein the first electrode is formed over a substrate and is located between the second electrode and the substrate, the light-emitting layer is located between the first electrode and the second electrode, the first layer is located between the first electrode and the light-emitting layer, and the second layer is located between the second electrode and the light-emitting layer, one of the first electrode and the second electrode is an anode and the other is a cathode, the light-emitting layer contains a first host material as a main component and a light-emitting substance as a minor component, and the first layer contains a light-emitting substance as a major component and a minor component. a light-emitting device having a first organic compound as a main component and a second organic compound as a main component, wherein the GSP_slope (mV / nm) of a vapor-deposited film of the main component of one of the light-emitting layer and the first layer, which is located closer to the cathode, is greater than the GSP_slope (mV / nm) of a vapor-deposited film of the main component of the other of the light-emitting layer and the second layer, which is located closer to the anode, is greater than the GSP_slope (mV / nm) of a vapor-deposited film of the main component of the other of the light-emitting layer and the second layer, which is located closer to the anode, is greater than the GSP_slope (mV / nm) of a vapor-deposited film of the main component of the other of the light-emitting layer and the second layer, which is located closer to the cathode, where GSP_slope (mV / nm) is a parameter expressed as ΔV / Δd when the change in surface potential ΔV (mV) is the change in film thickness Δd (nm).

[0022] Another embodiment of the present invention provides a light-emitting device including a first electrode, a second electrode, a light-emitting layer, a first layer, and a second layer, wherein the first electrode is electrically connected to a transistor, the light-emitting layer is located between the first electrode and the second electrode, the first layer is located between the first electrode and the light-emitting layer, the second layer is located between the second electrode and the light-emitting layer, one of the first electrode and the second electrode is an anode and the other is a cathode, the light-emitting layer contains a first host material as a main component and a light-emitting substance as a minor component, and the first layer contains a first host material as a main component. a light-emitting device comprising a first layer having a first organic compound as a main component, a second layer having a second organic compound as a main component, wherein the GSP_slope (mV / nm) of a vapor-deposited film of the main component of one of the light-emitting layer and the first layer located closer to the cathode is greater than the GSP_slope (mV / nm) of a vapor-deposited film of the main component of the one of the light-emitting layer and the second layer located closer to the anode, and the GSP_slope (mV / nm) of a vapor-deposited film of the main component of the one of the light-emitting layer and the second layer located closer to the anode is greater than the GSP_slope (mV / nm) of a vapor-deposited film of the main component of the one of the light-emitting layer and the second layer, where GSP_slope (mV / nm) is a parameter expressed as ΔV / Δd when the change in surface potential ΔV (mV) is the change in film thickness Δd (nm).

[0023] Another embodiment of the present invention provides a light-emitting device including a first electrode, a second electrode, a light-emitting layer, a first layer, and a second layer, wherein the first electrode is partially covered with an insulator, the light-emitting layer is located between the first electrode and the second electrode, the first layer is located between the first electrode and the light-emitting layer, the second layer is located between the second electrode and the light-emitting layer, one of the first electrode and the second electrode is an anode and the other is a cathode, the light-emitting layer contains a first host material as a main component and a light-emitting substance as a minor component, and the first layer contains a first organic compound as a main component. a light-emitting device comprising a first layer and a second layer, the first layer having a second organic compound as a main component, the GSP_slope (mV / nm) of a vapor-deposited film of the main component of one of the first and second layers located closer to the cathode being greater than the GSP_slope (mV / nm) of a vapor-deposited film of the main component of the other of the first and second layers located closer to the anode being greater than the GSP_slope (mV / nm) of a vapor-deposited film of the main component of the other of the first and second layers located closer to the anode being greater than the GSP_slope (mV / nm) of a vapor-deposited film of the main component of the other of the first and second layers, where GSP_slope (mV / nm) is a parameter expressed as ΔV / Δd when the change in film thickness Δd (nm) is the change in surface potential ΔV (mV).

[0024] Another embodiment of the present invention provides a light-emitting device including a first electrode, a second electrode, a light-emitting layer, a first layer, and a second layer, the first electrode being formed on an insulating film and being located between the second electrode and the insulating film, an external connection electrode being provided on the insulating film, the light-emitting layer being located between the first electrode and the second electrode, the first layer being located between the first electrode and the light-emitting layer, the second layer being located between the second electrode and the light-emitting layer, one of the first electrode and the second electrode being an anode and the other being a cathode, the light-emitting layer having a first host material as a main component and a light-emitting substance as a minor component, The first layer has a first organic compound as a main component, and the second layer has a second organic compound as a main component, and the GSP_slope (mV / nm) of the vapor-deposited film of the main component of the layer of the light-emitting layer and the first layer located closer to the cathode is greater than the GSP_slope (mV / nm) of the vapor-deposited film of the main component of the layer of the light-emitting layer and the second layer located closer to the anode, and the GSP_slope (mV / nm) of the vapor-deposited film of the main component of the layer of the light-emitting layer and the second layer located closer to the anode is greater than the GSP_slope (mV / nm) of the vapor-deposited film of the main component of the layer of the light-emitting layer and the second layer located closer to the cathode, where GSP_slope (mV / nm) is a parameter expressed as ΔV / Δd when the change in surface potential ΔV (mV) is the change in film thickness Δd (nm).

[0025] Another embodiment of the present invention provides a light-emitting device including a first electrode, a second electrode, an emitting layer, a first layer, and a second layer, wherein the first electrode is formed on a substrate and is located between the second electrode and the substrate, the emitting layer is located between the first electrode and the second electrode, the first layer is located between the first electrode and the emitting layer, and the second layer is located between the second electrode and the emitting layer, the first electrode is an anode, the second electrode is a cathode, and the emitting layer is a first host material and a second layer. and a light-emitting material, the first layer including a first organic compound, and the second layer including a second organic compound, wherein the GSP_slope (mV / nm) of a vapor-deposited film of the first host material is greater than the GSP_slope (mV / nm) of a vapor-deposited film of the first organic compound, which in turn is greater than the GSP_slope (mV / nm) of a vapor-deposited film of the first host material. The GSP_slope (mV / nm) is a parameter expressed as ΔV / Δd, where ΔV (mV) is a change in surface potential relative to Δd (nm) in film thickness. In this configuration, the first electrode may be electrically connected to a transistor. In this configuration, the first electrode may be partially covered with an insulator. In this configuration, the first electrode may be formed on an insulating film. Another embodiment of the present invention is a light-emitting device having the above configuration, which includes a third layer and a fourth layer, the third layer being located between the first layer and the first electrode, and the fourth layer being located between the second layer and the second electrode, the third layer including a third organic compound, and the fourth layer including a fourth organic compound, wherein the GSP_slope (mV / nm) of the evaporated film of the first organic compound is larger than the GSP_slope (mV / nm) of the evaporated film of the third organic compound, and the GSP_slope (mV / nm) of the evaporated film of the second organic compound is larger than the GSP_slope (mV / nm) of the evaporated film of the fourth organic compound.

[0026] Another embodiment of the present invention provides a light-emitting device including a first electrode, a second electrode, an emitting layer, a first layer, and a second layer, wherein the first electrode is formed on a substrate and is located between the second electrode and the substrate, the emitting layer is located between the first electrode and the second electrode, the first layer is located between the first electrode and the emitting layer, and the second layer is located between the second electrode and the emitting layer, the first electrode is a cathode, the second electrode is an anode, and the emitting layer is a first host material and a second layer. and a light-emitting material, the first layer including a first organic compound and the second layer including a second organic compound, wherein the GSP_slope (mV / nm) of a vapor-deposited film of the first organic compound is greater than the GSP_slope (mV / nm) of a vapor-deposited film of the first host material, and the GSP_slope (mV / nm) of a vapor-deposited film of the second organic compound is greater than the GSP_slope (mV / nm) of a vapor-deposited film of the first host material. Note that the GSP_slope (mV / nm) is a parameter expressed as ΔV / Δd, where ΔV (mV) is a change in surface potential relative to Δd (nm) in film thickness. In this configuration, the first electrode may be electrically connected to a transistor. In this configuration, a portion of the first electrode may be covered with an insulator. In this configuration, the first electrode may be formed on an insulating film. Another embodiment of the present invention is a light-emitting device having the above configuration, which includes a third layer and a fourth layer, the third layer being located between the first layer and the first electrode, and the fourth layer being located between the second layer and the second electrode, the third layer including a third organic compound, and the fourth layer including a fourth organic compound, wherein the GSP_slope (mV / nm) of the evaporated film of the third organic compound is greater than the GSP_slope (mV / nm) of the evaporated film of the first organic compound, and the GSP_slope (mV / nm) of the evaporated film of the fourth organic compound is greater than the GSP_slope (mV / nm) of the evaporated film of the second organic compound.

[0027] Another aspect of the present invention is a light-emitting device having any of the above configurations, wherein at least one of the refractive index of the film of the first organic compound and the refractive index of the film of the second organic compound is lower than the refractive index of the film of the first host material at the peak wavelength of the electroluminescence spectrum of the light-emitting device.

[0028] Another embodiment of the present invention provides a light-emitting device including a first electrode, a second electrode, a light-emitting layer, a first layer, and a second layer, wherein the first electrode is formed over a substrate and is located between the second electrode and the substrate, the light-emitting layer is located between the first electrode and the second electrode, the first layer is located between the first electrode and the light-emitting layer, and the second layer is located between the second electrode and the light-emitting layer, one of the first electrode and the second electrode is an anode and the other is a cathode, the light-emitting layer contains a first host material and a second host material as main components and a light-emitting substance as a minor component, and the first layer is a light-emitting device having a first organic compound as a main component, and a second layer having a second organic compound as a main component, wherein the GSP_slope (mV / nm) of a vapor-deposited film of the main component of one of the light-emitting layer and the first layer, which is located closer to the cathode, is greater than the GSP_slope (mV / nm) of a vapor-deposited film of the main component of the other of the light-emitting layer and the first layer, which is located closer to the anode, and the GSP_slope (mV / nm) of a vapor-deposited film of the main component of the other of the light-emitting layer and the second layer, which is located closer to the anode, is greater than the GSP_slope (mV / nm) of a vapor-deposited film of the main component of the light-emitting layer, where the GSP_slope (mV / nm) of the vapor-deposited film of the main component refers to the average of the GSP_slope (mV / nm) of the vapor-deposited film of the first host material and the GSP_slope (mV / nm) of the vapor-deposited film of the second host material. Furthermore, GSP_slope (mV / nm) is a parameter expressed as ΔV / Δd when the amount of change in surface potential is ΔV (mV) relative to the amount of change in film thickness Δd (nm).

[0029] Another embodiment of the present invention provides a light-emitting device including a first electrode, a second electrode, a light-emitting layer, a first layer, and a second layer. The first electrode is electrically connected to a transistor. The light-emitting layer is located between the first electrode and the second electrode. The first layer is located between the first electrode and the light-emitting layer. The second layer is located between the second electrode and the light-emitting layer. One of the first electrode and the second electrode is an anode, and the other is a cathode. The light-emitting layer contains a first host material and a second host material as main components and a light-emitting substance as a minor component. The first layer contains a light-emitting substance as a main component. a first organic compound as a main component of the light-emitting layer, and a second organic compound as a main component of the second layer, wherein the GSP_slope (mV / nm) of a vapor-deposited film of the main component of one of the light-emitting layer and the first layer, which is located closer to the cathode, is greater than the GSP_slope (mV / nm) of a vapor-deposited film of the main component of the layer of the light-emitting layer and the first layer, which is located closer to the anode, and the GSP_slope (mV / nm) of a vapor-deposited film of the main component of the layer of the light-emitting layer and the second layer, which is located closer to the anode, is greater than the GSP_slope (mV / nm) of a vapor-deposited film of the main component of the light-emitting layer, where the GSP_slope (mV / nm) of the vapor-deposited film of the main component refers to the average value of the GSP_slope (mV / nm) of the vapor-deposited film of the first host material and the GSP_slope (mV / nm) of the vapor-deposited film of the second host material. Furthermore, GSP_slope (mV / nm) is a parameter expressed as ΔV / Δd when the amount of change in surface potential is ΔV (mV) relative to the amount of change in film thickness Δd (nm).

[0030] Another embodiment of the present invention provides a light-emitting device including a first electrode, a second electrode, a light-emitting layer, a first layer, and a second layer, wherein the first electrode is partly covered with an insulator, the light-emitting layer is located between the first electrode and the second electrode, the first layer is located between the first electrode and the light-emitting layer, the second layer is located between the second electrode and the light-emitting layer, one of the first electrode and the second electrode is an anode and the other is a cathode, the light-emitting layer contains a first host material and a second host material as main components and a light-emitting substance as a minor component, and the first layer contains a second host material as a main component. a light-emitting device comprising a first organic compound and a second organic compound as a main component, wherein the GSP_slope (mV / nm) of a vapor-deposited film of the main component of one of the light-emitting layer and the first layer, which is located closer to the cathode, is greater than the GSP_slope (mV / nm) of a vapor-deposited film of the main component of the layer located closer to the anode, and the GSP_slope (mV / nm) of a vapor-deposited film of the main component of the one of the light-emitting layer and the second layer, which is located closer to the anode, is greater than the GSP_slope (mV / nm) of a vapor-deposited film of the main component of the light-emitting layer, where the GSP_slope (mV / nm) of the vapor-deposited film of the main component refers to the average of the GSP_slope (mV / nm) of the vapor-deposited film of the first host material and the GSP_slope (mV / nm) of the vapor-deposited film of the second host material. Furthermore, GSP_slope (mV / nm) is a parameter expressed as ΔV / Δd when the amount of change in surface potential is ΔV (mV) relative to the amount of change in film thickness Δd (nm).

[0031] Another embodiment of the present invention is a light-emitting device including a first electrode, a second electrode, a light-emitting layer, a first layer, and a second layer, wherein the first electrode is formed on an insulating film and is located between the second electrode and the insulating film, an external connection electrode is provided on the insulating film, the light-emitting layer is located between the first electrode and the second electrode, the first layer is located between the first electrode and the light-emitting layer, the second layer is located between the second electrode and the light-emitting layer, one of the first electrode and the second electrode is an anode and the other is a cathode, and the light-emitting layer contains a first host material and a second host material as main components and a light-emitting substance as a minor component. the first layer has a first organic compound as a main component, the second layer has a second organic compound as a main component, and the GSP_slope (mV / nm) of a vapor-deposited film of the main component of one of the light-emitting layer and the first layer, which is located closer to the cathode, is greater than the GSP_slope (mV / nm) of a vapor-deposited film of the main component of the layer located closer to the anode, and the GSP_slope (mV / nm) of a vapor-deposited film of the main component of the one of the light-emitting layer and the second layer, which is located closer to the anode, is greater than the GSP_slope (mV / nm) of a vapor-deposited film of the main component of the light-emitting layer, where the GSP_slope (mV / nm) of the vapor-deposited film of the main component refers to the average of the GSP_slope (mV / nm) of the vapor-deposited film of the first host material and the GSP_slope (mV / nm) of the vapor-deposited film of the second host material. Furthermore, GSP_slope (mV / nm) is a parameter expressed as ΔV / Δd when the amount of change in surface potential is ΔV (mV) relative to the amount of change in film thickness Δd (nm).

[0032] Another aspect of the present invention is a light-emitting device having the above-described configuration, which includes a third layer and a fourth layer, wherein the third layer is located between the first layer and the first electrode, and the fourth layer is located between the second layer and the second electrode, the third layer having a third organic compound as a main component, and the fourth layer having a fourth organic compound as a main component, and wherein the GSP_slope (mV / nm) of the evaporated film of the main component of the layer of the first and third layers located closer to the cathode is greater than the GSP_slope (mV / nm) of the evaporated film of the main component of the layer of the second and fourth layers located closer to the anode is greater than the GSP_slope (mV / nm) of the evaporated film of the main component of the layer of the second and fourth layers located closer to the anode.

[0033] Another embodiment of the present invention provides a light-emitting device including a first electrode, a second electrode, a light-emitting layer, a first layer, and a second layer. The first electrode is formed over a substrate and is located between the second electrode and the substrate. The light-emitting layer is located between the first electrode and the second electrode. The first layer is located between the first electrode and the light-emitting layer. The second layer is located between the second electrode and the light-emitting layer. The first electrode is an anode, and the second electrode is a cathode. The light-emitting layer includes a first host material, a second host material, and a light-emitting substance. The first layer includes a first organic compound. is a light-emitting device including a second organic compound, wherein the average GSP_slope (mV / nm) of the vapor-deposited film of the first host material and the average GSP_slope (mV / nm) of the vapor-deposited film of the second host material are greater than the GSP_slope (mV / nm) of the vapor-deposited film of the first organic compound, and the average GSP_slope (mV / nm) of the vapor-deposited film of the first host material and the average GSP_slope (mV / nm) of the vapor-deposited film of the second host material are greater than the GSP_slope (mV / nm) of the vapor-deposited film of the second organic compound. Note that the GSP_slope (mV / nm) is a parameter expressed as ΔV / Δd, where ΔV (mV) is a change in surface potential relative to Δd (nm) in film thickness. In this configuration, the first electrode may be electrically connected to a transistor. In this configuration, the first electrode may be partially covered with an insulator. In this configuration, the first electrode may be formed on an insulating film. Another embodiment of the present invention is a light-emitting device having the above configuration, which includes a third layer and a fourth layer, the third layer being located between the first layer and the first electrode, and the fourth layer being located between the second layer and the second electrode, the third layer including a third organic compound, and the fourth layer including a fourth organic compound, wherein the GSP_slope (mV / nm) of the evaporated film of the first organic compound is larger than the GSP_slope (mV / nm) of the evaporated film of the third organic compound, and the GSP_slope (mV / nm) of the evaporated film of the second organic compound is larger than the GSP_slope (mV / nm) of the evaporated film of the fourth organic compound.

[0034] Another embodiment of the present invention provides a light-emitting device including a first electrode, a second electrode, a light-emitting layer, a first layer, and a second layer. The first electrode is formed over a substrate and is located between the second electrode and the substrate. The light-emitting layer is located between the first electrode and the second electrode. The first layer is located between the first electrode and the light-emitting layer. The second layer is located between the second electrode and the light-emitting layer. The first electrode is a cathode, and the second electrode is an anode. The light-emitting layer includes a first host material, a second host material, and a light-emitting substance. The first layer includes a first organic compound, and the second layer includes a second organic compound. The light-emitting device has a GSP_slope (mV / nm) of a vapor-deposited film of the first organic compound that is greater than the GSP_slope (mV / nm) of a vapor-deposited film that is the average of the GSP_slope (mV / nm) of a vapor-deposited film of the first host material and the GSP_slope (mV / nm) of a vapor-deposited film of the second host material, and the GSP_slope (mV / nm) of a vapor-deposited film of the second organic compound that is greater than the average of the GSP_slope (mV / nm) of a vapor-deposited film of the first host material and the GSP_slope (mV / nm) of a vapor-deposited film of the second host material. The GSP_slope (mV / nm) is a parameter expressed as ΔV / Δd, where ΔV (mV) is a change in surface potential relative to Δd (nm) in film thickness. In this configuration, the first electrode may be electrically connected to a transistor. In this configuration, the first electrode may be partially covered with an insulator. In this configuration, the first electrode may be formed on an insulating film. Another embodiment of the present invention is a light-emitting device having the above configuration, which includes a third layer and a fourth layer, the third layer being located between the first layer and the first electrode, the fourth layer being located between the second layer and the second electrode, the third layer including a third organic compound, and the fourth layer including a fourth organic compound, wherein the GSP_slope (mV / nm) of the evaporated film of the third organic compound is larger than the GSP_slope (mV / nm) of the evaporated film of the first organic compound, and the GSP_slope (mV / nm) of the evaporated film of the fourth organic compound is larger than the GSP_slope (mV / nm) of the evaporated film of the second organic compound.

[0035] Another embodiment of the present invention is a light-emitting device having any of the above structures, wherein when the light-emitting layer contains a first host material but does not contain a second host material, at least one of the refractive index of the film of the first organic compound and the refractive index of the film of the second organic compound is lower than the refractive index of the film of the first host material at the peak wavelength of the electroluminescence spectrum of the light-emitting device.

[0036] Another aspect of the present invention is a light-emitting device having any of the above configurations, wherein when the light-emitting layer contains a first host material and a second host material, at least one of the refractive index of the film of the first organic compound and the refractive index of the film of the second organic compound is lower than the average value of the refractive index of the film of the first host material and the refractive index of the film of the second host material at the peak wavelength of the electroluminescence spectrum of the light-emitting device.

[0037] Another embodiment of the present invention is a light-emitting device having any of the above structures, wherein at least one of the refractive index of the film of the first organic compound and the refractive index of the film of the second organic compound is 1.75 or less at the peak wavelength of the electroluminescence spectrum of the light-emitting device.

[0038] Another embodiment of the present invention is a light-emitting device having any of the above structures, wherein 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.

[0039] Another embodiment of the present invention is a light-emitting device having any of the above structures, wherein when the light-emitting layer contains the first host material but does not contain the second host material, at least one of the refractive index of the film of the first organic compound, the refractive index of the film of the second organic compound, the refractive index of the film of the third organic compound, and the refractive index of the film of the fourth organic compound is lower than the refractive index of the film of the first host material at the peak wavelength of the electroluminescence spectrum of the light-emitting device.

[0040] Another aspect of the present invention is a light-emitting device having any of the above configurations, wherein when the light-emitting layer contains a first host material and a second host material, at least one of the refractive indexes of the film of the first organic compound, the film of the second organic compound, the film of the third organic compound, and the film of the fourth organic compound is lower than the average value of the refractive indexes of the film of the first host material and the film of the second host material at the peak wavelength of the electroluminescence spectrum of the light-emitting device.

[0041] Another embodiment of the present invention is a light-emitting device having the above structure, wherein at least one of the refractive index of the film of the first organic compound, the refractive index of the film of the second organic compound, the refractive index of the film of the third organic compound, and the refractive index of the film of the fourth organic compound is 1.75 or less at the peak wavelength of the electroluminescence spectrum of the light-emitting device.

[0042] Another embodiment of the present invention is a light-emitting device having the above structure, wherein at least one of the first organic compound, the second organic compound, 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.

[0043] Another embodiment of the present invention is a light-emitting device having the above structure, in which the first organic compound and the third organic compound each independently have a π-electron-rich heteroaromatic ring or an aromatic amine skeleton, and the HOMO level of the third organic compound is higher than the HOMO level of the first organic compound. [Effects of the Invention]

[0044] According to one embodiment of the present invention, a light-emitting device with low driving voltage can be provided. According to one embodiment of the present invention, a light-emitting device with high emission efficiency can be provided. Furthermore, according to one embodiment of the present invention, any of a light-emitting device, an electronic device, and a display device with low power consumption can be provided.

[0045] Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. Note that effects other than these will become apparent from the description in the specification, drawings, claims, etc., and it is possible to extract other effects from the description in the specification, drawings, claims, etc. [Brief explanation of the drawings]

[0046] [Figure 1] 1A and 1B are diagrams illustrating the configuration of a light-emitting device according to an embodiment. [Figure 2] 2A and 2B are diagrams illustrating the configuration of a light-emitting device according to an embodiment. [Figure 3] 3A to 3D are diagrams illustrating a configuration of a light-emitting device according to an embodiment. [Figure 4] 4A to 4E are diagrams illustrating the configuration of a light-emitting device according to an embodiment. [Figure 5] 5(A) and 5(B) are a top view and a cross-sectional view of the light-emitting device. [Figure 6] 6A to 6G are top views showing examples of pixel configurations. [Figure 7] 7A to 7I are top views showing examples of pixel configurations. [Figure 8] 8A and 8B are perspective views showing configuration examples of a display module. [Figure 9] 9(A) and 9(B) are cross-sectional views showing examples of the configuration of a light-emitting device. [Figure 10] FIG. 10 is a perspective view showing an example of the configuration of a light emitting device. [Figure 11] Fig. 11A is a cross-sectional view showing a structural example of a light-emitting device, Fig. 11B and Fig. 11C are cross-sectional views showing structural examples of a transistor. [Figure 12] FIG. 12 is a cross-sectional view showing an example of the configuration of a light emitting device. [Figure 13]13A to 13C are cross-sectional views and top views showing structural examples of a light-emitting device. [Figure 14] 14A to 14D are cross-sectional views showing examples of the configuration of a light-emitting device. [Figure 15] 15A to 15C are cross-sectional views and top views showing structural examples of a light-emitting device. [Figure 16] 16A to 16D are diagrams showing examples of electronic devices. [Figure 17] 17A to 17F are diagrams showing examples of electronic devices. [Figure 18] 18A to 18G are diagrams showing examples of electronic devices. [Figure 19] 19(A) and 19(B) are diagrams showing an active matrix light emitting device. [Figure 20] 20(A) and 20(B) are diagrams showing an active matrix light emitting device. [Figure 21] FIG. 21 is a diagram showing an active matrix light emitting device. [Figure 22] 22(A) and 22(B) are diagrams showing a passive matrix light emitting device. [Figure 23] 23A and 23B are diagrams illustrating an electronic device according to an embodiment. [Figure 24] FIG. 24 is a diagram illustrating an electronic device according to an embodiment. [Figure 25] 25(A) to 25(C) are diagrams illustrating the configuration of a device according to an embodiment. [Figure 26] FIG. 26 is a diagram showing the capacitance-voltage characteristics of the measuring device 1. As shown in FIG. [Figure 27] FIG. 27 is a diagram showing the current density-voltage characteristics of the measuring device 1. [Figure 28] FIG. 28 is a graph showing the luminance-current density characteristics of light-emitting device 1, light-emitting device 2, and comparative light-emitting devices 3 to 5. In FIG. [Figure 29]FIG. 29 is a graph showing the luminance-voltage characteristics of the light-emitting device 1, the light-emitting device 2, and the comparative light-emitting devices 3 to 5. In FIG. [Figure 30] FIG. 30 is a graph showing the current efficiency-luminance characteristics of the light-emitting device 1, the light-emitting device 2, and the comparative light-emitting devices 3 to 5. In FIG. [Figure 31] FIG. 31 is a graph showing the current density-voltage characteristics of light-emitting device 1, light-emitting device 2, and comparative light-emitting devices 3 to 5. In FIG. [Figure 32] FIG. 32 is a graph showing the power efficiency-luminance characteristics of the light-emitting device 1, the light-emitting device 2, and the comparative light-emitting devices 3 to 5. In FIG. [Figure 33] FIG. 33 is a graph showing the external quantum efficiency-luminance characteristics of the light-emitting device 1, the light-emitting device 2, and the comparative light-emitting devices 3 to 5. In FIG. [Figure 34] FIG. 34 is a graph showing electroluminescence spectra of light-emitting device 1, light-emitting device 2, and comparative light-emitting devices 3 to 5. As shown in FIG. [Figure 35] FIG. 35 is a graph showing the luminance-current density characteristics of light-emitting devices 6 to 8 and comparative light-emitting device 9. In FIG. [Figure 36] FIG. 36 is a graph showing the luminance-voltage characteristics of light-emitting devices 6 to 8 and comparative light-emitting device 9. In FIG. [Figure 37] FIG. 37 is a graph showing the current efficiency-luminance characteristics of light-emitting devices 6 to 8 and comparative light-emitting device 9. In FIG. [Figure 38] FIG. 38 is a graph showing the current density-voltage characteristics of light-emitting devices 6 to 8 and comparative light-emitting device 9. In FIG. [Figure 39] FIG. 39 is a graph showing the power efficiency-luminance characteristics of light-emitting devices 6 to 8 and comparative light-emitting device 9. In FIG. [Figure 40] FIG. 40 is a graph showing the external quantum efficiency-luminance characteristics of light-emitting devices 6 to 8 and comparative light-emitting device 9. In FIG. [Figure 41]FIG. 41 is a graph showing the blue index-luminance characteristics of the light-emitting devices 6 to 8 and the comparative light-emitting device 9. In FIG. [Figure 42] FIG. 42 shows the electroluminescence spectra of light-emitting devices 6 to 8 and comparative light-emitting device 9. As shown in FIG. [Figure 43] FIG. 43 is a graph showing the luminance-current density characteristics of the light-emitting device 10, the light-emitting device 11, and the comparative light-emitting devices 12 to 14. In FIG. [Figure 44] FIG. 44 is a graph showing the luminance-voltage characteristics of the light-emitting device 10, the light-emitting device 11, and the comparative light-emitting devices 12 to 14. In FIG. [Figure 45] FIG. 45 is a graph showing the current density-voltage characteristics of the light-emitting device 10, the light-emitting device 11, and the comparative light-emitting devices 12 to 14. In FIG. [Figure 46] FIG. 46 is a graph showing the electroluminescence spectra of light-emitting device 10, light-emitting device 11, and comparative light-emitting devices 12 to 14. [Figure 47] Figure 47 is the 1H NMR spectrum of oBP-mmchPh-mDMePyPTzn. [Figure 48] FIG. 48 shows the absorption and emission spectra of a dichloromethane solution of oBP-mmchPh-mDMePyPTzn. [Figure 49] Figure 49 is the 1H NMR spectrum of mmtBuBP-DMePy2PTzn. [Figure 50] FIG. 50 shows the absorption and emission spectra of a dichloromethane solution of mmtBuBP-DMePy2PTzn. DETAILED DESCRIPTION OF THE INVENTION

[0047] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and various changes in form and details are possible without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the description of the embodiments shown below.

[0048] For ease of understanding, the position, size, range, etc. of each component shown in the drawings may not represent the actual position, size, range, etc. Therefore, the disclosed invention is not necessarily limited to the position, size, range, etc. disclosed in the drawings, etc.

[0049] In addition, in this specification and the like, ordinal numbers such as "first," "second," etc. are used for convenience and may not indicate the order of processes or stacking. Therefore, for example, "first" can be appropriately replaced with "second," "third," etc. in the description. Furthermore, the ordinal numbers used to identify one embodiment of the present invention may not match the ordinal numbers used in this specification and the like.

[0050] Furthermore, in this specification and the like, when describing the configuration of the invention using drawings, the same reference numerals may be used in common between different drawings.

[0051] Furthermore, in this specification and the like, the terms "film" and "layer" can be interchangeable. For example, the term "conductive layer" can be changed to the term "conductive film." Or, for example, the term "insulating film" can be changed to the term "insulating layer."

[0052] (Embodiment 1) In this embodiment, a light-emitting device 10A which is a light-emitting device of one embodiment of the present invention and a light-emitting device 10B which is another light-emitting device of one embodiment of the present invention will be described with reference to FIGS.

[0053] As shown in FIGS. 1 and 2 , the light-emitting device 10A and the light-emitting device 10B are each located on a substrate 1000. The light-emitting device 10A and the light-emitting device 10B each include 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. The organic compound layer 103 includes at least a light-emitting layer 113, a first carrier transport layer 116, and a second carrier transport layer 117. The first electrode 101 is formed on the substrate 1000. In the organic compound layer 103, the first carrier transport layer 116 is located between the first electrode 101 and the light-emitting layer 113, and the second carrier transport layer 117 is located between the second electrode 102 and the light-emitting layer 113. In the light-emitting device 10A and the light-emitting device 10B, the first electrode 101 is provided between the second electrode 102 and the substrate 1000. That is, the first electrode 101 is an electrode that is 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 through a wiring. Alternatively, the first electrode 101 is provided on an insulating layer on which an external connection electrode is provided, which is used as a terminal for attaching an FPC or the like. Furthermore, the first electrode 101 may be partially covered with an insulator on the substrate 1000 or the insulating layer on which the first electrode 101 is provided.

[0054] The light-emitting device 10A shown in FIG. 1 and the light-emitting device 10B shown in FIG. 2 differ in the functions of the first electrode 101 and the second electrode 102. In the light-emitting device 10A shown in FIG. 1, the first electrode 101 functions as an anode, and the second electrode 102 functions as a cathode. On the other hand, in the light-emitting device 10B shown in FIG. 2, the first electrode 101 functions as a cathode, and the second electrode 102 functions as an anode. In this specification and the like, a light-emitting device in which the first electrode provided on the substrate side functions as an anode, such as the light-emitting device 10A shown in FIG. 1, is sometimes referred to as a forward-stacked light-emitting device, and a light-emitting device in which the first electrode provided on the substrate side functions as a cathode, such as the light-emitting device 10B shown in FIG. 2, is sometimes referred to as a reverse-stacked light-emitting device.

[0055] 1 emits light when holes injected from the first electrode 101, which functions as an anode, into the organic compound layer 103 and electrons injected from the second electrode 102, which functions as a cathode, into the organic compound layer 103 recombine in the light-emitting layer 113. Therefore, in the light-emitting device 10A, it is preferable that the first carrier transport layer 116 has a function of transporting holes, and the second carrier transport layer 117 has a function of transporting electrons.

[0056] 2 emits light when electrons injected from the first electrode 101, which functions as a cathode, into the organic compound layer 103 and holes injected from the second electrode 102, which functions as an anode, into the organic compound layer 103 recombine in the light-emitting layer 113. Therefore, in the light-emitting device 10B, it is preferable that the first carrier transport layer 116 has a function of transporting electrons, and the second carrier transport layer 117 has a function of transporting holes.

[0057] In the light-emitting device 10A and the light-emitting device 10B, the first carrier transport layer 116 and the second carrier transport layer 117 may each be a single layer or a laminate of multiple layers. The organic compound layer 103 of the light-emitting device 10A shown in FIG. 1B and the light-emitting device 10B shown in FIG. 2B includes at least the light-emitting layer 113, the first carrier transport layer 116_1, the first carrier transport layer 116_2, the second carrier transport layer 117_1, and the second carrier transport layer 117_2. In the organic compound layer 103 of the light-emitting device 10A and the light-emitting device 10B, it is preferable that the first carrier transport layer 116_1 is located between the first electrode 101 and the light-emitting layer 113, the first carrier transport layer 116_2 is located between the first carrier transport layer 116_1 and the light-emitting layer 113, the second carrier transport layer 117_1 is located between the second electrode 102 and the light-emitting layer 113, and the second carrier transport layer 117_2 is located between the second carrier transport layer 117_1 and the second electrode 102. Note that, hereinafter, the first carrier transport layer 116_1 and the first carrier transport layer 116_2 may be collectively referred to as the first carrier transport layer 116, and the second carrier transport layer 117_1 and the second carrier transport layer 117_2 may be collectively referred to as the second carrier transport layer 117.

[0058] Furthermore, the light-emitting device 10A and the light-emitting device 10B preferably have a hole injection layer 111 between the anode and the layer having a hole transporting function, and more preferably have an electron injection layer 115 between the cathode and the layer having an electron transporting function. The stacked-type light-emitting device 10A shown in Fig. 1(A) has a structure in which the hole injection layer 111, the first carrier transporting layer 116, the light-emitting layer 113, the second carrier transporting layer 117, the electron injection layer 115, and the second electrode 102 functioning as a cathode are sequentially stacked on the first electrode 101 functioning as an anode. 1B has a structure in which a hole injection layer 111, a first carrier transport layer 116_1, a first carrier transport layer 116_2, a light-emitting layer 113, a second carrier transport layer 117_1, a second carrier transport layer 117_2, an electron injection layer 115, and a second electrode 102 functioning as a cathode are sequentially stacked on a first electrode 101 functioning as an anode. 2A has a structure in which an electron injection layer 115, a first carrier transport layer 116, a light-emitting layer 113, a second carrier transport layer 117, a hole injection layer 111, and a second electrode 102 functioning as an anode are sequentially stacked on a first electrode 101 functioning as a cathode. 2(B) has a structure in which an electron injection layer 115, a first carrier transport layer 116_1, a first carrier transport layer 116_2, a light-emitting layer 113, a second carrier transport layer 117_1, a second carrier transport layer 117_2, a hole injection layer 111, and a second electrode 102 functioning as an anode are sequentially stacked on a first electrode 101 functioning as a cathode. Note that in the inverted-stack light-emitting device 10B, an electron relay layer, a charge generation buffer layer, etc. may be further provided between the hole injection layer 111 and the second electrode 102 functioning as an anode.

[0059] The configurations of light-emitting devices 10A and 10B are not limited to those shown in FIGS. 1 and 2. For example, they may be configured to have one layer of either a hole transport layer or an electron transport layer and two layers of the other. They may also be configured to have three or more layers of either or both of a hole transport layer and an electron transport layer. They may also be configured to have a functional layer that has the function of 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.

[0060] The inventors have discovered that in light-emitting device 10A and light-emitting device 10B, the driving voltage can be reduced by selecting materials for each layer such that the GSP_slope of the layer of light-emitting layer 113 and first carrier transport layer 116 located on the cathode side is larger than the GSP_slope of the layer of light-emitting layer 113 located on the anode side, and the GSP_slope of the layer of light-emitting layer 113 and second carrier transport layer 117 located on the anode side is larger than the GSP_slope of the layer of light-emitting layer 113 located on the cathode side.

[0061] GSP is a phenomenon caused by spontaneous orientation polarization (SOP) that occurs when the orientation of the permanent electric dipole moment of a deposited film is biased in the direction of the film thickness.

[0062] The surface potential of a vapor-deposited film that exhibits GSP changes at a constant rate without saturating as the film thickness increases. For example, the surface potential of a vapor-deposited film of tris(8-quinolinolato)aluminum (abbreviated as Alq3) at a film thickness of 560 nm is approximately 28 V. This electric field strength is 5×10 5 V / cm, which is comparable to the electric field strength during operation of a typical light-emitting device.

[0063] GSP_slope is a parameter expressed as ΔV / Δd, where ΔV (mV) is the change in surface potential relative to Δd (nm) in film thickness, where GSP changes in proportion to the film thickness. Note that if the surface potential increases with increasing film thickness, the GSP_slope is positive, and if the surface potential decreases with increasing film thickness, the GSP_slope is negative. The above-mentioned Alq3 can be said to be a material with a positive GSP_slope. Note that in layers with a positive GSP_slope, the substrate side has a low potential, and in layers with a negative GSP_slope, the substrate side has a high potential.

[0064] As mentioned above, this GSP is a phenomenon caused by the SOP, which occurs when the orientation of the permanent electric dipole moment is biased in the film thickness direction. In other words, in a layer where the 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 a layer where the 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.

[0065] Since evaporated films of organic compounds often have a positive GSP_slope, for example, when a second layer is deposited on a first layer, the signs of the GSP_slope of the first and second layers are the same (positive). In this case, the polarization charge on the first layer side of the second layer is offset by the polarization charge on the second layer side of the first layer, and only the remaining charge becomes the interface charge (fixed charge) at the interface between the first and second layers.

[0066] In one embodiment of the present invention, the polarization charge and the interface charge in the laminated film resulting from the polarization charge are utilized to reduce the driving voltage of the light-emitting device.

[0067] In the light-emitting device 10A (see FIG. 1(A)) and the light-emitting device 10B (see FIG. 2(A)) having the first carrier transport layer 116 and the second carrier transport layer 117, it is preferable that the GSP_slope of the layer of the light-emitting layer 113 and the first carrier transport layer 116 located on the cathode side is larger than the GSP_slope of the layer located on the anode side, and that the GSP_slope of the layer of the light-emitting layer 113 and the second carrier transport layer 117 located on the anode side is larger than the GSP_slope of the layer located on the cathode side.

[0068] In the forward-stacked light-emitting device 10A (see FIG. 1(A)) having the first carrier transport layer 116 and the second carrier transport layer 117, the first electrode 101 functions as an anode, and the second electrode 102 functions as a cathode, as described above. Therefore, in the forward-stacked light-emitting device, the layer located on the cathode side of the light-emitting layer 113 and the first carrier transport layer 116 refers to the light-emitting layer 113, and the layer located on the anode side refers to the first carrier transport layer 116. Furthermore, the layer located on the anode side of the light-emitting layer 113 and the second carrier transport layer 117 refers to the light-emitting layer 113, and the layer located on the cathode side refers to the second carrier transport layer 117. That is, in the case of a stacked light-emitting device 10A (see Figure 1(A)) having a first carrier transport layer 116 and a second carrier transport layer 117, it is preferable that the GSP_slope of the light-emitting layer 113 is larger than the GSP_slope of the first carrier transport layer 116, and that the GSP_slope of the light-emitting layer 113 is larger than the GSP_slope of the second carrier transport layer 117.

[0069] 1A, the polarization charge on the light-emitting layer 113 side of the first carrier transport layer 116 is offset by the polarization charge on the first carrier transport layer 116 side of the light-emitting layer 113, leaving a negative interface charge 50a at the interface between the first carrier transport layer 116 and the light-emitting layer 113. This negative interface charge 50a attracts holes from the first electrode 101 side to the interface of the light-emitting layer 113 on the first electrode 101 side, making it possible to effectively apply an electric field to the light-emitting layer 113. Furthermore, the polarization charge on the second carrier transport layer 117 side of the light-emitting layer 113 is offset by the polarization charge on the light-emitting layer 113 side of the second carrier transport layer 117, leaving a positive interface charge 50b at the interface between the light-emitting layer 113 and the second carrier transport layer 117. This positive interface charge 50b attracts electrons from the second electrode 102 side to the interface of the light-emitting layer 113 on the second electrode 102 side, making it possible to effectively apply an electric field to the light-emitting layer 113. Therefore, since it becomes easy to effectively apply an electric field to the light-emitting layer 113, the driving voltage of the light-emitting device can be reduced.

[0070] On the other hand, in the inverted-stack light-emitting device 10B (see FIG. 2(A)) having the first carrier transport layer 116 and the second carrier transport layer 117, the first electrode 101 functions as a cathode and the second electrode 102 functions as an anode, as described above. Therefore, in the case of the inverted-stack light-emitting device, the layer located on the cathode side of the light-emitting layer 113 and the first carrier transport layer 116 refers to the first carrier transport layer 116, and the layer located on the anode side refers to the light-emitting layer 113. Furthermore, the layer located on the anode side of the light-emitting layer 113 and the second carrier transport layer 117 refers to the second carrier transport layer 117, and the layer located on the cathode side refers to the light-emitting layer 113. That is, in the case of an inverted-stack light-emitting device 10B (see FIG. 2(A)) having a first carrier transport layer 116 and a second carrier transport layer 117, it is preferable that the GSP_slope of the first carrier transport layer 116 is larger than the GSP_slope of the light-emitting layer 113, and that the GSP_slope of the second carrier transport layer 117 is larger than the GSP_slope of the light-emitting layer 113.

[0071] 2A, the polarization charge on the light-emitting layer 113 side of the first carrier transport layer 116 is offset by the polarization charge on the first carrier transport layer 116 side of the light-emitting layer 113, leaving a positive interface charge 50b at the interface between the first carrier transport layer 116 and the light-emitting layer 113. This positive interface charge 50b attracts electrons from the first electrode 101 side to the interface of the light-emitting layer 113 on the first electrode 101 side, making it possible to effectively apply an electric field to the light-emitting layer 113. Furthermore, the polarization charge on the second carrier transport layer 117 side of the light-emitting layer 113 is offset by the polarization charge on the light-emitting layer 113 side of the second carrier transport layer 117, leaving a negative interface charge 50a at the interface between the light-emitting layer 113 and the second carrier transport layer 117. This negative interface charge 50a attracts holes from the second electrode 102 side to the interface of the light-emitting layer 113 on the second electrode 102 side, making it possible to effectively apply an electric field to the light-emitting layer 113. Therefore, since it becomes easy to effectively apply an electric field to the light-emitting layer 113, the driving voltage of the light-emitting device can be reduced.

[0072] When the light-emitting device 10A has a plurality of first carrier transport layers 116 and a plurality of second carrier transport layers 117, it is preferable that the GSP_slope of the light-emitting layer 113 be the largest among the plurality of first carrier transport layers 116, the light-emitting layer 113, and the plurality of second carrier transport layers 117. In addition to this configuration, it is more preferable that the GSP_slope of the layer of the plurality of first carrier transport layers 116 located closer to the light-emitting layer 113 be larger than the GSP_slope of the layer of the plurality of second carrier transport layers 117 located closer to the light-emitting layer 113, and that the GSP_slope of the layer of the plurality of second carrier transport layers 117 located closer to the light-emitting layer 113 be larger than the GSP_slope of the layer of the plurality of second carrier transport layers 117 located closer to the second electrode 102.

[0073] Furthermore, in the light-emitting device 10A and the light-emitting device 10B having a plurality of first carrier transport layers 116 and a plurality of second carrier transport layers 117, it is preferable that the GSP_slope of the layer of the light-emitting layer 113 and the first carrier transport layer 116 that is closer to the cathode is larger than the GSP_slope of the layer of the light-emitting layer 113 and the second carrier transport layer 117 that is closer to the anode is larger than the GSP_slope of the layer of the light-emitting layer 113 and the second carrier transport layer 117 that is closer to the anode.

[0074] In the case of the light-emitting device 10A and the light-emitting device 10B (see FIGS. 1B and 2B) having a plurality of first carrier transport layers (first carrier transport layer 116_1 and first carrier transport layer 116_2) and a plurality of second carrier transport layers (second carrier transport layer 117_1 and second carrier transport layer 117_2), the GSP_slope of the layer located on the cathode side of the light-emitting layer 113 and the first carrier transport layer 116_1 is larger than the GSP_slope of the layer located on the anode side, and Preferably, the GSP_slope of the layer of the first carrier transport layer 116_2 located closer to the cathode is larger than the GSP_slope of the layer of the layer of the first carrier transport layer 116_2 located closer to the anode, the GSP_slope of the layer of the light-emitting layer 113 and the second carrier transport layer 117_1 located closer to the anode is larger than the GSP_slope of the layer of the light-emitting layer 113 and the second carrier transport layer 117_2 located closer to the anode is larger than the GSP_slope of the layer of the light-emitting layer 113 and the second carrier transport layer 117_2 located closer to the cathode. In addition to the above configuration, it is even more preferable that the GSP_slope of the layer of the first carrier transport layer 116_1 and the first carrier transport layer 116_2 located closer to the cathode is larger than the GSP_slope of the layer of the second carrier transport layer 117_1 and the second carrier transport layer 117_2 located closer to the anode ... cathode.

[0075] In the stacked-type light-emitting device 10A shown in FIG. 1B, as described above, the first electrode 101 functions as an anode, and the second electrode 102 functions as a cathode. Therefore, in this light-emitting device, the layer of the light-emitting layer 113 and the first carrier transport layer 116_1 that is located on the cathode side refers to the light-emitting layer 113, and the layer of the anode side refers to the first carrier transport layer 116_1. Furthermore, the layer of the light-emitting layer 113 and the first carrier transport layer 116_2 that is located on the cathode side refers to the light-emitting layer 113, and the layer of the anode side refers to the first carrier transport layer 116_2. Furthermore, the layer of the first carrier transport layer 116_1 and the first carrier transport layer 116_2 that is located on the cathode side refers to the first carrier transport layer 116_2, and the layer of the anode side refers to the first carrier transport layer 116_1. Furthermore, of the light-emitting layer 113 and the second carrier transport layer 117_1, the layer located on the anode side refers to the light-emitting layer 113, and the layer located on the cathode side refers to the second carrier transport layer 117_1. Furthermore, of the light-emitting layer 113 and the second carrier transport layer 117_2, the layer located on the anode side refers to the light-emitting layer 113, and the layer located on the cathode side refers to the second carrier transport layer 117_2. Furthermore, of the second carrier transport layer 117_1 and the second carrier transport layer 117_2, the layer located on the anode side refers to the second carrier transport layer 117_1, and the layer located on the cathode side refers to the second carrier transport layer 117_2.

[0076] 1B, it is preferable that the GSP_slope of the light-emitting layer 113 is larger than the GSP_slope of the first carrier transport layer 116_1, the GSP_slope of the first carrier transport layer 116_2, the GSP_slope of the second carrier transport layer 117_1, and the GSP_slope of the second carrier transport layer 117_2. In addition to this configuration, it is more preferable that the GSP_slope of the first carrier transport layer 116_2 is larger than the GSP_slope of the first carrier transport layer 116_1, and the GSP_slope of the second carrier transport layer 117_1 is larger than the GSP_slope of the second carrier transport layer 117_2.

[0077] 1B, negative interface charges 50a remain at the interface between the first carrier transport layer 116_1 and the first carrier transport layer 116_2 and at the interface between the first carrier transport layer 116_2 and the light-emitting layer 113. The negative interface charges 50a attract holes from the first electrode 101 side to the interface of the light-emitting layer 113 on the first electrode 101 side, thereby enabling an electric field to be applied effectively to the light-emitting layer 113. Furthermore, positive interface charges 50b remain at the interface between the light-emitting layer 113 and the second carrier transport layer 117_1 and at the interface between the second carrier transport layer 117_1 and the second carrier transport layer 117_2. The positive interface charges 50b attract electrons from the second electrode 102 side to the interface of the light-emitting layer 113 on the second electrode 102 side, thereby enabling an electric field to be applied effectively to the light-emitting layer 113. Therefore, it becomes easy to effectively apply an electric field to the light-emitting layer 113, and the driving voltage of the light-emitting device can be reduced.

[0078] On the other hand, in the inverted-stack light-emitting device 10B shown in FIG. 2(B), as described above, the first electrode 101 functions as a cathode, and the second electrode 102 functions as an anode. Therefore, in this light-emitting device, of the light-emitting layer 113 and the first carrier transport layer 116_1, the layer located on the cathode side refers to the first carrier transport layer 116_1, and the layer located on the anode side refers to the light-emitting layer 113. Furthermore, of the light-emitting layer 113 and the first carrier transport layer 116_2, the layer located on the cathode side refers to the first carrier transport layer 116_2, and the layer located on the anode side refers to the light-emitting layer 113. Furthermore, of the first carrier transport layer 116_1 and the first carrier transport layer 116_2, the layer located on the cathode side refers to the first carrier transport layer 116_1, and the layer located on the anode side refers to the first carrier transport layer 116_2. Furthermore, of the light-emitting layer 113 and the second carrier transport layer 117_1, the layer located on the anode side refers to the second carrier transport layer 117_1, and the layer located on the cathode side refers to the light-emitting layer 113. Furthermore, of the light-emitting layer 113 and the second carrier transport layer 117_2, the layer located on the anode side refers to the second carrier transport layer 117_2, and the layer located on the cathode side refers to the light-emitting layer 113. Furthermore, of the second carrier transport layer 117_1 and the second carrier transport layer 117_2, the layer located on the anode side refers to the second carrier transport layer 117_2, and the layer located on the cathode side refers to the second carrier transport layer 117_1.

[0079] 2(B), it is preferable that the GSP_slope of the first carrier transport layer 116_1, the GSP_slope of the first carrier transport layer 116_2, the GSP_slope of the second carrier transport layer 117_1, and the GSP_slope of the second carrier transport layer 117_2 are all larger than the GSP_slope of the light-emitting layer 113. In addition to this configuration, it is more preferable that the GSP_slope of the first carrier transport layer 116_1 is larger than the GSP_slope of the first carrier transport layer 116_2, and the GSP_slope of the second carrier transport layer 117_2 is larger than the GSP_slope of the second carrier transport layer 117_1.

[0080] As a result, as shown in FIG. 2B , positive interface charges 50b remain at the interface between the first carrier transport layer 116_1 and the first carrier transport layer 116_2 and at the interface between the first carrier transport layer 116_2 and the light-emitting layer 113. The positive interface charges 50b attract electrons from the first electrode 101 side to the interface of the light-emitting layer 113 on the first electrode 101 side, making it possible to effectively apply an electric field to the light-emitting layer 113. Furthermore, negative interface charges 50a remain at the interface between the light-emitting layer 113 and the second carrier transport layer 117_1 and at the interface between the second carrier transport layer 117_1 and the second carrier transport layer 117_2. The negative interface charges 50a attract holes from the second electrode 102 side to the interface of the light-emitting layer 113 on the second electrode 102 side, making it possible to effectively apply an electric field to the light-emitting layer 113. Therefore, it becomes easy to effectively apply an electric field to the light-emitting layer 113, and the driving voltage of the light-emitting device can be reduced.

[0081] <How to calculate GSP_slope> Here, a method for determining the GSP_slope of a film formed by vacuum deposition of an organic compound will be described.

[0082] The phenomenon in which the surface potential of a deposited film increases in proportion to the film thickness is called giant surface potential, as mentioned above. Generally, the slope of the surface potential of a deposited film measured by a Kelvin probe plotted against the film thickness is discussed as a parameter that represents the magnitude of the giant surface potential, i.e., GSP_slope (mV / nm). However, when two different layers are stacked, the charge density (mC / m 2 ) varies in relation to GSP, which can be used to estimate GSP_slope.

[0083] Non-Patent Document 1 shows that when organic thin films (thin film 1 and thin film 2, where thin film 1 is located on the anode side and thin film 2 is located on the cathode side, and the anode is located on the substrate side) with different spontaneous polarizations are stacked and a voltage is applied, if the carriers accumulated at the interface are holes, the following equation holds true:

[0084]

number

[0085]

number

[0086] 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 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. The dielectric constant is the ordinary refractive index n o In this way, the square of V (633 nm) can be used. i , V bi The dielectric constant ε2 of thin film 2 calculated from the refractive index and the thickness d2 of thin film 2 are used to calculate the interface charge density σ if_h can be obtained.

[0087] Next, in equation (2), σif_h is the interfacial charge density, P n is the spontaneous polarization of thin film n (n is 1 or 2) in the substrate normal direction, ε n is the dielectric constant of the thin film n, V n is the potential at the membrane surface, d n is the thickness of the thin film n. The potential on the film surface (V n ) to the film thickness (d n ) and the interfacial charge density σ if_h Therefore, by using a material with a known GSP_slope as thin film 2 and adopting an appropriate dielectric constant, the GSP_slope of thin film 1 can be estimated.

[0088] Therefore, a measurement device 1 was fabricated using tris(8-quinolinolato)aluminum (abbreviated as Alq3), which has a known GSP_slope of 48 (mV / nm), as the thin film 2. The following example shows how the GSP_slope of 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviated as NPB) was measured.

[0089] The device structure of measurement device 1 is as shown in Table 1. Layer 1_1 of measurement device 1, from the cathode, was formed from the anode side by vacuum deposition under conditions of room temperature substrate temperature and a deposition rate of 0.2 nm / sec to 0.6 nm / sec. Deposition was continued without stopping deposition 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.

[0090] When fabricating the measuring device, the film formation rate of each layer is preferably 3 nm / min to 600 nm / min, and the film thickness of each layer in the measuring device is preferably 3 nm to 500 nm, more preferably 50 nm to 300 nm.

[0091] The capacitance-voltage characteristics of the measurement device 1 are shown in FIG.

[0092] [Table 1]

[0093] Table 2 shows the hole injection voltage V of the measurement device 1, which was calculated using FIG. 26 and equations (1) and (2). i , threshold voltage V bi , interfacial charge density σ if_h , GSP_slope, and the refractive index of NPB used in the calculation, n o and the refractive index n of Alq3 o The refractive index was measured using a spectroscopic ellipsometer (M-2000U manufactured by J.A. Woollam Japan).

[0094] [Table 2]

[0095] We also fabricated measurement device 2, which has almost the same configuration as measurement device 1, except that the Alq3 film thickness is 80 nm, and confirmed that the hole injection voltage is shifted lower than that of measurement device 1. This suggests that in such a device, holes are injected first, and charges accumulate at the interface with Alq3. We also estimated the GSP_slope using measurement device 2 in the same way as measurement device 1, and confirmed that the same results were obtained.

[0096] In addition, the threshold voltage V bi If it is difficult to estimate, the threshold voltage estimated from the current density-voltage characteristics may be used.

[0097] The current density-voltage characteristics of the measuring device 1 are shown in FIG.

[0098] V estimated from current density-voltage characteristics bi was 2.0 V, which was the same value as estimated from the capacitance-voltage characteristics.

[0099] In this way, by fabricating a device in which a film of Alq3, whose GSP_slope is known, and a film formed from an organic compound whose GSP_slope is to be determined are stacked, and measuring the capacitance-voltage characteristics, it is possible to estimate the GSP_slope of the organic compound.

[0100] In the above explanation, a method for calculating GSP_slope was explained for a structure in which the carriers accumulated at the interface are holes. However, when calculating the GSP_slope of an organic film for a structure in which the carriers accumulated at the interface are electrons, it can be calculated in the same way by using the following formulas (3) and (4). In the following formulas (3) and (4), σ if_e is the interfacial charge density.

[0101]

number

[0102]

number

[0103] It is preferable to select an organic compound to be used in each layer of a light-emitting device in consideration of the GSP_slope of the evaporated film of the organic compound, which is measured in advance by the above-mentioned measurement method.

[0104] Light-emitting devices sometimes use layers formed by co-evaporating multiple organic compounds. Because the GSP_slope of a co-evaporated layer varies depending on the combination and mixing ratio of the organic compounds, it is ideal to measure the GSP_slope of a film co-evaporated 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 taking this GSP_slope into consideration. However, this method requires preparing different co-evaporated films for each combination or mixing ratio of organic compounds and measuring the GSP_slope, which makes the experiment for selecting organic compounds cumbersome.

[0105] Therefore, when a layer in a light-emitting device contains multiple organic compounds, it is preferable to select the organic compound by considering the average of the GSP_slope values ​​of the vapor-deposited films of each organic compound measured in advance as the GSP_slope of that layer. This makes it relatively easy to select an organic compound taking GSP_slope into consideration.

[0106] However, even if a layer contains multiple organic compounds, if the contents of the compounds vary significantly, the GSP_slope of the vapor-deposited film of the organic compound with the highest content can be considered to be the GSP_slope of the layer, and the organic compound can be selected accordingly. For example, if a layer contains two organic compounds, and the content of one organic compound is less than 20% by weight of the total organic compound content in the layer, the organic compound is considered to be a minor component of the layer, and the other organic compound with the highest content is considered to be the major component of the layer, and the GSP_slope of the vapor-deposited film of the major component can be considered to be the GSP_slope of the layer. Also, if a layer contains three or four organic compounds, and the content of one organic compound is less than 20% by weight of the total organic compound content in the layer, the organic compound is considered to be a minor component of the layer, and the remaining organic compounds are considered to be major components of the layer, and the average GSP_slope of the vapor-deposited films of the major components can be considered to be the GSP_slope of the layer.

[0107] 3A and 3B, the light-emitting layer 113 of the light-emitting device 10A will be described. In the light-emitting layer 113, the host material 118 is present in the largest amount by weight, and the guest material 119 is dispersed in the host material 118.

[0108] The light-emitting layer 113 shown in FIG. 3A contains a guest material 119 and a host material 118. The guest material 119 is a light-emitting substance. In the light-emitting layer 113, 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 FIG. 3A can be said to contain the host material 118 as a main component and the guest material 119 as a subcomponent. Therefore, it is preferable to select organic compounds to be used in each layer of the light-emitting device by regarding the GSP_slope of the light-emitting layer 113 containing only one type of host material as the GSP_slope of a vapor-deposited film of the host material 118, which is the main component.

[0109] 3(B) includes a guest material 119, a first host material 118_1, and a second host material 118_2. In the light-emitting layer 113, the contents of the first host material 118_1 and the second host material 118_2 are each preferably 25% by weight or more, 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 FIG. 3(B) can be said to include two types of host materials (the first host material 118_1 and the second host material 118_2) as main components and the guest material 119 as a secondary component. Therefore, it is preferable to select organic compounds to be used in each layer of the light-emitting device by regarding the GSP_slope of the light-emitting layer 113 having the first host material 118_1 and the second host material 118_2 as the main components as the average value of the GSP_slope of the evaporated film of the first host material 118_1 and the GSP_slope of the evaporated film of the second host material 118_2.

[0110] 3C and 3D, the first carrier-transporting layer 116 is a layer containing an organic compound 116C as a main component, and the second carrier-transporting layer 117 is a layer containing an organic compound 117C as a main component. Although not shown, the first carrier-transporting layer 116_1 is a layer containing an organic compound 116_1C as a main component, the first carrier-transporting layer 116_2 is a layer containing an organic compound 116_2C as a main component, the second carrier-transporting layer 117_1 is a layer containing an organic compound 117_1C as a main component, and the second carrier-transporting layer 117_2 is a layer containing an organic compound 117_2C as a main component.

[0111] Therefore, when light-emitting device 10A and light-emitting device 10B are designed so that the GSP_slope of the layer of light-emitting layer 113 and first carrier transport layer 116 located on the cathode side is larger than the GSP_slope of the layer of light-emitting layer 113 and first carrier transport layer 116 located on the anode side, and the GSP_slope of the layer of light-emitting layer 113 and second carrier transport layer 117 located on the anode side is larger than the GSP_slope of the layer of light-emitting layer 113 and second carrier transport layer 117 located on the cathode side, it is preferable to select the organic compound used for each layer as shown in the following example.

[0112] In the light-emitting devices 10A and 10B (see Figures 1(A) and 2(A)) having the first carrier transport layer 116 and the second carrier transport layer 117, it is preferable that the GSP_slope of the vapor-deposited film of the main component of the layer located on the cathode side of the light-emitting layer 113 and the first carrier transport layer 116 is larger than the GSP_slope of the vapor-deposited film of the main component of the layer located on the anode side, and that the GSP_slope of the vapor-deposited film of the main component of the layer located on the anode side of the light-emitting layer 113 and the second carrier transport layer 117 is larger than the GSP_slope of the vapor-deposited film of the main component of the layer located on the cathode side. However, when 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 main components, the GSP_slope of the vapor-deposited film of the main components 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.

[0113] For example, in a stacked light-emitting device 10A (see FIG. 1A) having a first carrier transport layer 116 and a second carrier transport layer 117, when the light-emitting layer 113 has one type of host material 118 as a main component (see FIG. 3A), it is preferable that the GSP_slope of the vapor-deposited film of the host material 118 is larger than the GSP_slope of the vapor-deposited film of the organic compound 116C and the GSP_slope of the vapor-deposited film of the organic compound 117C.

[0114] Furthermore, for example, in a stacked light-emitting device 10A (see FIG. 1(A)) having a first carrier transport layer 116 and a second carrier transport layer 117, when the light-emitting layer 113 has a structure (see FIG. 3(B)) including two types of host materials (a first host material 118_1 and a second host material 118_2), it is preferable that the average value of the GSP_slope of the evaporated film of the first host material 118_1 and the GSP_slope of the evaporated film of the second host material 118_2 be larger than the GSP_slope of the evaporated film of the organic compound 116C and the GSP_slope of the evaporated film of the organic compound 117C.

[0115] In a light-emitting device 10A and a light-emitting device 10B (see FIGS. 1(B) and 2(B)) having a plurality of first carrier transport layers (first carrier transport layer 116_1 and first carrier transport layer 116_2) and a plurality of second carrier transport layers (second carrier transport layer 117_1 and second carrier transport layer 117_2), the GSP_slope of the vapor-deposited film of the main component of the layer located on the cathode side of the light-emitting layer 113 and the first carrier transport layer 116_1 is larger than the GSP_slope of the vapor-deposited film of the main component of the layer located on the anode side, and That is, it is preferable that the GSP_slope of the vapor-deposited film of the main component of the layer located on the cathode side is larger than the GSP_slope of the vapor-deposited film of the main component of the layer located on the anode side, that the GSP_slope of the vapor-deposited film of the main component of the layer located on the anode side of the light-emitting layer 113 and the second carrier transport layer 117_1 is larger than the GSP_slope of the vapor-deposited film of the main component of the layer located on the cathode side, and that the GSP_slope of the vapor-deposited film of the main component of the layer located on the anode side of the light-emitting layer 113 and the second carrier transport layer 117_2 is larger than the GSP_slope of the vapor-deposited film of the main component of the layer located on the cathode side. In addition to this configuration, it is more preferable that the GSP_slope of the vapor-deposited film of the main component of the layer located closer to the cathode, of the first carrier transport layers 116_1 and 116_2, be larger than the GSP_slope of the vapor-deposited film of the main component of the layer located closer to the anode, and that the GSP_slope of the vapor-deposited film of the main component of the layer located closer to the anode, of the second carrier transport layers 117_1 and 117_2, be larger than the GSP_slope of the vapor-deposited film of the main component of the layer located closer to the cathode. However, when the light-emitting layer 113 has two host materials (a first host material 118_1 and a second host material 118_2) as 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] For example, in a stacked light-emitting device 10A (see Figure 1(B)) having multiple first carrier transport layers (first carrier transport layer 116_1 and first carrier transport layer 116_2) and multiple second carrier transport layers (second carrier transport layer 117_1 and second carrier transport layer 117_2), when the light-emitting layer 113 has a configuration containing one type of host material 118 (see Figure 3(A)), it is preferable that the GSP_slope of the evaporated film of the host material 118 is larger than the GSP_slope of the evaporated film of the organic compound 116_1C, the GSP_slope of the evaporated film of the organic compound 116_2C, the GSP_slope of the evaporated film of the organic compound 117_1C, and the GSP_slope of the evaporated film of the organic compound 117_2C. In addition to this configuration, it is more preferable that the GSP_slope of the evaporated film of the organic compound 116_2C is larger than the GSP_slope of the evaporated film of the organic compound 116_1C, and that the GSP_slope of the evaporated film of the organic compound 117_1C is larger than the GSP_slope of the evaporated film of the organic compound 117_2C.

[0117] Furthermore, for example, in a stacked-type light-emitting device 10A (see FIG. 1(B)) having a plurality of first carrier transport layers (first carrier transport layers 116_1 and 116_2) and a plurality of second carrier transport layers (second carrier transport layers 117_1 and 117_2), the light-emitting layer 113 has a structure including two types of host materials (first host material 118_1 and second host material 118_2) (see FIG. 3(B)). In the case of (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 larger than the GSP_slope of the vapor-deposited film of the organic compound 116_1C, the GSP_slope of the vapor-deposited film of the organic compound 116_2C, the GSP_slope of the vapor-deposited film of the organic compound 117_1C, and the GSP_slope of the vapor-deposited film of the organic compound 117_2C. In addition to this configuration, it is more preferable that the GSP_slope of the vapor-deposited film of the organic compound 116_2C is larger than the GSP_slope of the vapor-deposited film of the organic compound 116_1C, and the GSP_slope of the vapor-deposited film of the organic compound 117_1C is larger than the GSP_slope of the vapor-deposited film of the organic compound 117_2C.

[0118] As in the above example, the driving voltage of the light-emitting device 10A and the light-emitting device 10B can be reduced by selecting an organic compound for each layer. However, the structure of the light-emitting device according to one embodiment of the present invention is not limited to the above example.

[0119] For example, when a layer formed by co-depositing multiple organic compounds is used for one or more of the first carrier transport layer 116 and the second carrier transport layer 117, the GSP_slope of a film formed by co-depositing the same combination of organic compounds at the same mixing ratio can be measured in advance, and the organic compound can be selected taking this GSP_slope into consideration. Alternatively, as described above, the average of the GSP_slope values ​​of the pre-measured vapor-deposited films of the organic compounds can be considered to be the GSP_slope of the layer formed by co-depositing multiple organic compounds, and organic compounds can be selected accordingly. Furthermore, when the contents of the multiple organic compounds in the layer differ significantly, the organic compound with the highest content can be determined as the main component, and the GSP_slope of the vapor-deposited film of that main component can be considered to be the GSP_slope of the layer.

[0120] Furthermore, for example, in the case of a light-emitting device having three or more first carrier transport layers 116 and three or more second carrier transport layers 117, the organic compounds can be selected so that the GSP_slope of the evaporated film of the organic compound used in the layer of the three or more first carrier transport layers 116 located closer to the cathode is larger than the GSP_slope of the organic compound used in the layer located closer to the anode, and the GSP_slope of the evaporated film of the organic compound used in the layer of the three or more second carrier transport layers 117 located closer to the anode is higher than the GSP_slope of the evaporated film of the organic compound used in the layer located closer to the cathode.

[0121] Furthermore, in addition to the above structure, if the refractive index of the first carrier transport layer 116 and the second carrier transport layer 117 of the light-emitting device of one embodiment of the present invention is made smaller, the light extraction efficiency can be further increased, and therefore, an excellent light-emitting device with high emission efficiency and low driving voltage can be realized.

[0122] Therefore, it is more preferable to select the organic compound to be used in each layer of the light-emitting device in consideration of the refractive index of the organic compound film measured in advance in addition to GSP_slope.

[0123] Furthermore, when one layer contains multiple organic compounds, the refractive index of a film made of the same combination of organic compounds and in the same mixing ratio can be measured in advance, and the organic compounds can be selected taking that refractive index into consideration. Alternatively, the average of the refractive indexes of the films of each organic compound measured in advance can be considered as the refractive index of the layer, and the organic compounds can be selected.

[0124] However, even if a layer contains multiple organic compounds, if the contents of the multiple organic compounds differ significantly, the refractive index of the film of the organic compound with the largest content among the multiple organic compounds can be considered to be the refractive index of the layer, and the organic compound can be selected accordingly. For example, if a layer contains two organic compounds, and the content of one organic compound is less than 20% by weight of the total content of the organic compounds in the layer, that organic compound can be omitted, and the refractive index of the film of the other organic compound can be considered to be the refractive index of the layer. Furthermore, if a layer contains three or more organic compounds, and the content of one organic compound is less than 20% by weight of the total content of the organic compounds in the layer, that organic compound can be omitted, and the average refractive index of the films of the remaining organic compounds can be considered to be the refractive index of the layer.

[0125] In addition, the refractive index of the light-emitting layer 113 (see Figure 3(A)) containing only one type of host material can be considered to be the refractive index of a film of the host material 118, and organic compounds used in each layer of the light-emitting device can be selected.

[0126] In addition, the refractive index of the light-emitting layer 113 (see Figure 3(B)) having two types of host materials can be considered to be 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 organic compounds to be used in each layer of the light-emitting device can be selected.

[0127] Therefore, in light-emitting device 10A and light-emitting device 10B, in addition to taking GSP_slope into consideration, when the refractive index of first carrier transport layer 116 and second carrier transport layer 117 is designed to be low, the light extraction efficiency of the light-emitting device can be improved by selecting the organic compound used in each layer, as in the following example.

[0128] For example, in light-emitting devices 10A and 10B (see FIGS. 1A and 2A) having a first carrier transport layer 116 and a second carrier transport layer 117, when the light-emitting layer 113 has only one type of host material 118 (see FIG. 3A), it is more preferable that at least one of the refractive indexes of the film of organic compound 116C and the film of organic compound 117C is lower than the refractive index of the film of host material 118 at the peak wavelength of the electroluminescence spectrum of the light-emitting device, and it is even more preferable that the refractive indexes of the two films are lower than the refractive index of the film of host material 118. Furthermore, it is more preferable that at least one of the refractive indexes of the film of organic compound 116C and the film of organic compound 117C 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 indexes of the two films are 1.75 or less.

[0129] Furthermore, for example, in the light-emitting device 10A and the light-emitting device 10B (see FIGS. 1A and 2A) having the first carrier transport layer 116 and the second carrier transport layer 117, when the light-emitting layer 113 has two types of host materials (a first host material 118_1 and a second host material 118_2) (see FIG. 3B), it is more preferable that at least one of the refractive indexes of the film of the organic compound 116C and the film of the organic compound 117C is lower than the average value of the refractive indexes 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, and it is even more preferable that the refractive indexes of the two films are lower than the average value of the refractive indexes of the film of the first host material 118_1 and the film of the second host material 118_2. Furthermore, at the peak wavelength of the electroluminescence spectrum of the light-emitting device, it is more preferable that at least one of the refractive index of the film of organic compound 116C and the refractive index of the film of organic compound 117C is 1.75 or less, and it is even more preferable that the refractive indexes of the two films are 1.75 or less.

[0130] Furthermore, for example, in light-emitting devices 10A and 10B (see Figures 1(B) and 2(B)) having a plurality of first carrier transport layers (first carrier transport layer 116_1 and first carrier transport layer 116_2) and a plurality of second carrier transport layers (second carrier transport layer 117_1 and second carrier transport layer 117_2), when the light-emitting layer 113 has only one type of host material 118 (see Figure 3(A)), it is more preferable that at least one of the refractive indexes of the film of organic compound 116_1C, the film of organic compound 116_2C, the film of organic compound 117_1C, and the film of organic compound 117_2C is lower than the refractive index of the film of host material 118 at the peak wavelength of the electroluminescence spectrum of the light-emitting device, and it is even more preferable that the refractive indexes of the two or more films are lower than the refractive index of the film of host material 118. Furthermore, at the peak wavelength of the electroluminescence spectrum of the light-emitting device, it is more preferable that at least one of the refractive index of the film of organic compound 116_1C, the refractive index of the film of organic compound 116_2C, the refractive index of the film of organic compound 117_1C, and the refractive index of the film of organic compound 117_2C is 1.75 or less, and it is even more preferable that the refractive index of these two or more films is 1.75 or less.

[0131] Furthermore, for example, in the light-emitting devices 10A and 10B (see FIGS. 1B and 2B) each having a plurality of first carrier transport layers (first carrier transport layers 116_1 and 116_2) and a plurality of second carrier transport layers (second carrier transport layers 117_1 and 117_2), when the light-emitting layer 113 has a structure including two types of host materials (first host material 118_1 and second host material 118_2) (see FIG. 3B), the electroluminescence spectrum of the light-emitting device At a peak wavelength of the electroluminescence spectrum of the light-emitting device, it is more preferable that at least one of the refractive index of the film of the organic compound 116_1C, the refractive index of the film of the organic compound 116_2C, the refractive index of the film of the organic compound 117_1C, and the refractive index of the film of the organic compound 117_2C 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 or more 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. Furthermore, at a peak wavelength of the electroluminescence spectrum of the light-emitting device, it is more preferable that at least one of the refractive index of the film of the organic compound 116_1C, the refractive index of the film of the organic compound 116_2C, the refractive index of the film of the organic compound 117_1C, and the refractive index of the film of the organic compound 117_2C is 1.75 or less, and it is even more preferable that the refractive index of the two or more films is 1.75 or less. In addition, when the electroluminescence spectrum has multiple peak wavelengths, it is preferable that the refractive index at at least one of the peak wavelengths or the maximum peak wavelength has the above-mentioned configuration. Also, the refractive index at the peak wavelength of the emission spectrum of the light-emitting material used in the light-emitting device may have the above-mentioned configuration. The emission spectrum of the light-emitting material can be measured in a thin film or solution.

[0132] As a material with a low refractive index, it is preferable to use an organic compound in which an alkyl group having a smaller polarizability than the aromatic skeleton is bonded to the aromatic skeleton, and in particular, 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 is more preferable.

[0133] However, when films are formed by vacuum deposition using compounds with typical alkyl groups and aromatic backbones, they tend to exhibit very large positive GSP slopes. This is because the alkyl groups exhibit electron-donating properties relative to the aromatic backbone, which tends to generate a positively charged permanent electric dipole moment on the alkyl group side. Furthermore, aromatic backbones are more easily attracted to the underlying substrate, electrodes, and previously deposited organic materials by van der Waals forces than alkyl groups, which tends to orient the alkyl groups toward the film surface.

[0134] As described above, in a light-emitting device according to one embodiment of the present invention, not only is the refractive index of the first carrier transport layer 116 and the second carrier transport layer 117 low, but the relationship between the GSP_slope of the layer and the surrounding layers is also important. In a forward-stacked light-emitting device, the GSP_slope of the first carrier transport layer 116 and the second carrier transport layer 117 is required to be small, while in a reverse-stacked light-emitting device, the GSP_slope of the first carrier transport layer 116 and the second carrier transport layer 117 is required to be large. Therefore, in a reverse-stacked light-emitting device, it is preferable to form the first carrier transport layer 116 and the second carrier transport layer 117 by vacuum deposition using a low-refractive-index material having a general alkyl group and an aromatic skeleton, since this easily results in a film exhibiting a very large positive GSP_slope. On the other hand, in a forward-stacked light-emitting device, a compound having an elaboration of the molecular structure and an alkyl group and an aromatic skeleton that can form a vapor-deposited film exhibiting a small GSP_slope is required.

[0135] Specific examples of organic compounds that can be used in the light-emitting layer 113, first carrier transport layer 116, and second carrier transport layer 117 of a stacked-type light-emitting device are described below using structural formulas. The GSP_slope and refractive index of the evaporated film of each organic compound listed below as a specific example are shown in Example 1 or Example 2.

[0136] The host material 118 of the light-emitting layer 113 is preferably an organic compound that produces a vapor-deposited film with a relatively large GSP_slope. More specifically, it is preferable to use an organic compound having a heteroaromatic ring containing at least one of a nitrogen atom, an oxygen atom, and a sulfur atom. Furthermore, among heteroaromatic rings containing at least one of a nitrogen atom, an oxygen atom, and a sulfur atom, it is more preferable to use an organic compound having a heteroaromatic ring with low symmetry. The presence of such a heteroaromatic ring facilitates the generation of a strong permanent electric dipole moment in the molecule, and the use of such an organic compound facilitates the production of a film with a high GSP_slope. Specific examples of heteroaromatic rings containing at least one of a nitrogen atom, an oxygen atom, and a sulfur atom include a dibenzofuran ring, a benzonaphthofuran ring, a dibenzothiophene ring, an imidazole ring, a carbazole ring, and an indolocarbazole ring.

[0137] Specific examples of organic compounds that can be used as the host material 118 in the light-emitting layer 113 of a stacked-type light-emitting device include 4-(9H-carbazol-9-yl)-8-(dibenzofuran-2-yl)-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8DBf-4CzBfpm), 12,12'-(biphenyl-3,3'-diyl)bis(5,12-dihydro-5-phenylindolo[3,2-a]-5H,12H-carbazole) (abbreviation: mICz2BP), 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.

[0138] [ka]

[0139] The organic compound used in the first carrier transport layer 116 of a stacked-type light-emitting device preferably has hole transport properties and a relatively small GSP slope of the deposited film. More specifically, organic compounds having an aromatic or heteroaromatic skeleton, such as a π-electron-rich heteroaromatic ring or an aromatic amine skeleton, are preferred. Organic compounds containing nitrogen and having a highly symmetric aromatic or heteroaromatic skeleton are even more preferred. In such skeletons, the polarization caused by the nitrogen element is suppressed or canceled by the molecular symmetry, making it difficult for a permanent electric dipole moment to be generated in the molecule, and thus making it easier to obtain a film with a low GSP slope. 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 or heteroaromatic skeletons containing nitrogen and having a high symmetry include a triphenylamine skeleton and a 3,3'-bicarbazole skeleton.

[0140] Specific examples of organic compounds used in the first carrier transport layer 116 of the stacked type light-emitting device include N,N-bis(biphenyl-4-yl)-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: BBASF), N-(biphenyl-2-yl)-N-(3'',5',5''-tri-tert-butyl-[1,1':3',1''-terphenyl]-4-yl)-9,9-dimethyl-9H-fluorene-2-amine (abbreviation: mmtBumTPoFBi-04), N,N-bis(4-cyclohexylphenyl)-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: dchPASF), N-phenyl-N-[4-(9-phenyl Examples of organic compounds with a π-electron-rich heteroaromatic ring or aromatic amine skeleton include N-(3',5'-di-tert-butyl-biphenyl-4-yl)-N-(9,9-dimethyl-9H-fluoren-4-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBuBiFF-02), and N-(3',5'-ditert-butylbiphenyl-4-yl)-N-(biphenyl-2-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBuBioFBi). Their structural formulas are shown below.

[0141] [ka]

[0142] Among the above organic compounds, mmtBumTPoFBi-04, dchPASF, mmtBuBiFF-02, and mmtBuBioFBi have a low refractive index because they are organic compounds 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. Therefore, they are more preferable organic compounds for use in the first carrier transport layer 116 of a stacked-type light-emitting device.

[0143] The organic compound used in the second carrier transport layer 117 of the forward-stacked light-emitting device is preferably an organic compound that has electron transport properties and a relatively small GSP_slope of the deposited film. More specifically, an organic compound containing at least one of nitrogen, oxygen, and sulfur atoms and having a highly symmetric heteroaromatic skeleton is more preferred. In this skeleton, the polarization generated by at least one of nitrogen, oxygen, and sulfur atoms is suppressed or canceled due to the symmetry of the molecule, making it difficult for a permanent electric dipole moment to be generated in the molecule, and making it easier to obtain a film with a low GSP_slope. Examples of highly symmetric heteroaromatic skeletons containing at least one of nitrogen, oxygen, and sulfur atoms include pyrimidine, pyrazine, triazine, and 4,4'-bipyridine.

[0144] Specific examples of the organic compound used in the second carrier transport layer 117 of the stacked type light-emitting device include 2-{3-(2,6-dimethylpyridin-3-yl)-5-[(3,5-di-tert-butyl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mmtBuPh-mDMePyPTzn), 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthryl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn), 2-(biphenyl-2-yl)-4-[3-(3,5-dicyclohexylphenyl)-5-(2,6-dimethylpyridin-3-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn), Examples of organic compounds with π-electron-deficient heteroaromatic rings include 2-[3,5-bis(2,6-dimethylpyridin-3-yl)phenyl]-4-(3',5'-di-tert-butylbiphenyl-4-yl)-6-phenyl-1,3,5-triazine (abbreviation: mmtBuBP-DMePy2PTzn), 2,4,6-tris(3'-(pyridin-3-yl)biphenyl-3-yl)-1,3,5-triazine (abbreviation: TmPPPyTz), and 8-quinolinolato-lithium (abbreviation: Liq). Their structural formulas are shown below.

[0145] [ka]

[0146] Among the above organic compounds, mmtBuPh-mDMePyPTzn, oBP-mmchPh-mDMePyPTzn, and mmtBuBP-DMePy2PTzn have a low refractive index because they are organic compounds 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. Therefore, they are more preferable organic compounds for use in the second carrier transport layer 117 of a forward-stacked light-emitting device.

[0147] In general, in the laminated structure from the hole injection layer to the light-emitting layer of a light-emitting device, if a material with a high HOMO level is used in the layer on the hole injection layer side and a material with a low HOMO level is used in the layer on the light-emitting layer side, a hole barrier resulting from a potential gap is generated at the interface between the layers, making it difficult to inject holes and likely resulting in a problem of high driving voltage for the light-emitting device.

[0148] However, in the light-emitting device of one embodiment of the present invention, the driving voltage can be reduced by utilizing the interfacial charge in the stacked film resulting from the polarization charge. Therefore, even if the HOMO level of the organic compound 116_1C is higher than the HOMO level of the organic compound 116_2C, for example, the driving voltage of the light-emitting device can be reduced.

[0149] The values ​​of the HOMO level and LUMO level used in this specification can be determined by electrochemical measurements, such as cyclic voltammetry (CV) and differential pulse voltammetry (DPV).

[0150] In cyclic voltammetry (CV) measurements, the values ​​of the HOMO and LUMO levels (E) are determined by the oxidation peak potential (E pa ), and reduction peak potential (Epc ) can be calculated based on the following. In the measurement, the HOMO level is obtained from a potential scan in the positive direction, and the LUMO level is obtained from a potential scan in the negative direction. The scan rate in the measurement is 0.1 V / s.

[0151] The specific procedure for calculating the HOMO and LUMO levels is explained below. The oxidation peak potential (E pa ), and reduction peak potential (E pc ) to obtain the standard redox potential (E o )(=(E pa +E pc ) / 2) and calculate the potential energy (E x ) to obtain the values ​​of the HOMO and LUMO levels (E) (=E x -E o ) can be calculated respectively.

[0152] The above shows the case where a reversible redox wave is obtained. However, when an irreversible redox wave is obtained, the oxidation peak potential (E pa ) minus a fixed value (0.1 eV) to determine the reduction peak potential (E pc ) and the standard redox potential (E o ) to one decimal place. Also, to calculate the LUMO level, the reduction peak potential (E pc ) plus a certain value (0.1 eV) is taken as the oxidation peak potential (E pa ) and the standard redox potential (E o ) to one decimal place.

[0153] Note that the compound described in this embodiment can be used in appropriate combination with any of the structures described in other embodiments.

[0154] (Embodiment 2) In this embodiment, other structures of the light-emitting device of one embodiment of the present invention will be described with reference to FIGS.

[0155] <Basic structure of light-emitting devices> The basic structure of a light-emitting device will be described. Figure 4(A) shows a light-emitting device having a structure (single structure) in which an organic compound layer including a light-emitting layer is disposed between a pair of electrodes. Specifically, the light-emitting device has a structure in which an organic compound layer 103 is sandwiched between a first electrode 101 and a second electrode 102.

[0156] 4B shows a light-emitting device with a stacked structure (tandem structure) having multiple (two in FIG. 4B) 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.

[0157] The charge generation layer 106 has a function of injecting electrons into one organic compound layer (103a or 103b) and injecting holes into the other organic compound layer (103b or 103a) when a potential difference is generated between the first electrode 101 and the second electrode 102. Therefore, in FIG. 4B, when a voltage is applied to the first electrode 101 so that the potential thereof 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.

[0158] From the viewpoint of light extraction efficiency, the charge generation layer 106 is preferably transparent to visible light (specifically, the visible light transmittance of the charge generation layer 106 is 40% or more). The charge generation layer 106 functions even if it has lower conductivity than the first electrode 101 and the second electrode 102.

[0159] FIG. 4C shows a stacked structure of the organic compound layer 103 of the 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 stacked over the first electrode 101. The light-emitting layer 113 may have a stacked structure of a plurality of light-emitting layers emitting different light colors. 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 stacked, or a layer containing a carrier-transporting material may be interposed between the light-emitting layers. Alternatively, a light-emitting layer containing a yellow light-emitting substance and a light-emitting layer containing a blue light-emitting substance may be combined. However, the stacked structure of the light-emitting layer 113 is not limited to the above. For example, the light-emitting layer 113 may have a structure in which multiple light-emitting layers emitting the same light-emitting 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 are stacked, or a layer containing a carrier-transporting material is interposed between the layers. A structure in which multiple light-emitting layers emitting the same light-emitting color are stacked may have higher reliability than a single-layer structure. Even in the case of a tandem structure having multiple organic compound layers as shown in FIG. 4B, each organic compound layer is stacked in order from the anode side as described above. When the first electrode 101 functions as a cathode and the second electrode 102 functions as an anode, the stacking order of the organic compound layers 103 is reversed. Specifically, the structure is such that 111 on the first electrode 101 functioning as a cathode 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.

[0160] The light-emitting layers 113 included in the organic compound layers (103, 103a, 103b) each contain a light-emitting substance and an appropriate combination of multiple substances, and can be configured to emit fluorescent or phosphorescent light of a desired emission color. The light-emitting layer 113 may also have a stacked structure with different emission colors. In this case, different materials may be used for the light-emitting substance and other substances used in each stacked light-emitting layer. Alternatively, a structure in which different emission colors are emitted from the multiple organic compound layers (103a, 103b) shown in Figure 4(B) may also be used. In this case, different materials may be used for the light-emitting substance and other substances used in each light-emitting layer.

[0161] In addition, in a light-emitting device according to one embodiment of the present invention, for example, the first electrode 101 shown in FIG. 4C may be a reflective electrode, the second electrode 102 may be a semi-transmissive and semi-reflective electrode, and a micro-optical resonator (microcavity) structure may be formed. This allows light emitted from the light-emitting layer 113 included in the organic compound layer 103 to resonate between the two electrodes, thereby enhancing the intensity of light emitted from the second electrode 102. This makes it easy to achieve high definition. Furthermore, the intensity of light emitted from a specific wavelength in the front direction can be enhanced, thereby reducing power consumption.

[0162] When the first electrode 101 of the light-emitting device is a reflective electrode having a laminated structure of a reflective conductive material and a light-transmitting 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 mλ / 2 (where m is an integer of 1 or greater) or in the vicinity thereof, for the wavelength λ of light obtained from the light-emitting layer 113.

[0163] Furthermore, in order to amplify the desired light (wavelength: λ) obtained from the light-emitting layer 113, it is preferable to adjust the optical distance from the first electrode 101 to the region (light-emitting region) in the light-emitting layer 113 where the desired light is obtained and the optical distance from the second electrode 102 to the region (light-emitting region) in the light-emitting layer 113 where the desired light is obtained to be (2m'+1)λ / 4 (where m' is an integer of 1 or greater) or close to that. Note that the light-emitting region here refers to the recombination region of holes and electrons in the light-emitting layer 113.

[0164] By performing such optical adjustment, the spectrum of the specific monochromatic light obtained from the light-emitting layer 113 can be narrowed, and light emission with good color purity can be obtained.

[0165] In the above case, the optical distance between the first electrode 101 and the second electrode 102 can be strictly defined as the total thickness from the reflective region of the first electrode 101 to the reflective region of the second electrode 102. However, since it is difficult to precisely determine the reflective regions of the first electrode 101 and the second electrode 102, the above-mentioned effect can be sufficiently achieved by assuming any position of the first electrode 101 and the second electrode 102 as the reflective region. Furthermore, the optical distance between the first electrode 101 and the light-emitting layer from which desired light is obtained can be strictly defined as the optical distance between the reflective region of the first electrode 101 and the light-emitting region of the light-emitting layer from which desired light is obtained. However, since it is difficult to precisely determine the reflective region of the first electrode 101 and the light-emitting region of the light-emitting layer from which desired light is obtained, the above-mentioned effect can be sufficiently achieved by assuming any position of the first electrode 101 as the reflective region and any position of the light-emitting layer from which desired light is obtained as the light-emitting region.

[0166] The light-emitting device shown in Figure 4(D) has a tandem structure. The tandem structure allows the device to emit light with high brightness. Furthermore, the tandem structure can reduce the current required to obtain the same brightness compared to a single structure, thereby improving reliability. Furthermore, power consumption can be reduced.

[0167] The light-emitting device shown in FIG. 4(E) is an example of the tandem-structure light-emitting device shown in FIG. 4(B). As shown in the figure, the light-emitting device has a structure in which three organic compound layers (103a, 103b, 103c) are stacked with charge generation layers (106a, 106b) sandwiched between them. Each of the three organic compound layers (103a, 103b, 103c) has a light-emitting layer (113a, 113b, 113c), and the light-emitting colors of the light-emitting layers can be freely combined. For example, the light-emitting layer 113a can be blue, the light-emitting layer 113b can be red, green, or yellow, and the light-emitting layer 113c can be blue. Alternatively, the light-emitting layer 113a can be red, the light-emitting layer 113b can be blue, green, or yellow, and the light-emitting layer 113c can be red.

[0168] In the light-emitting device according to one embodiment of the present invention, 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-transmitting / semi-reflective electrode). When the light-transmitting electrode is a transparent electrode, the visible light transmittance of the transparent electrode is 40% or more. In addition, when the semi-transmitting / semi-reflective electrode is used, the visible light reflectance of the semi-transmitting / semi-reflective electrode is 20% or more and 80% or less, preferably 40% or more and 70% or less. Furthermore, these electrodes have a resistivity of 1×10 -2 It is preferable to keep it at Ω·cm or less.

[0169] In the above-described light-emitting device according to one embodiment of the present invention, when one of the first electrode 101 and the second electrode 102 is a reflective electrode (a reflective electrode), the reflectivity of the reflective electrode for visible light is set to 40% to 100%, preferably 70% to 100%. -2 It is preferable to keep it at Ω·cm or less.

[0170] <Specific structure of light-emitting device> Next, a specific structure of a light-emitting device according to one embodiment of the present invention will be described. Here, a description will be given using FIG. 4D, which has a tandem structure. The single-structure light-emitting devices shown in FIGS. 4A and 4C also have the same organic compound layer structure. When the light-emitting device shown in FIG. 4D has a microcavity structure, the first electrode 101 is formed as a reflective electrode, and the second electrode 102 is formed as a semi-transmissive and semi-reflective electrode. Therefore, a single or multiple desired electrode materials can be used to form a single layer or a stacked layer. The second electrode 102 is formed by selecting an appropriate material after the organic compound layer 103b is formed.

[0171] <Light-emitting device materials> <Light-emitting layer> The light-emitting layers (113, 113a, 113b) are layers containing a light-emitting substance. Light-emitting substances that can be used for the light-emitting layers (113, 113a, 113b) include substances that emit light of colors such as blue, purple, blue-purple, green, yellow-green, yellow, orange, and red. When multiple light-emitting layers are provided, different light-emitting substances can be used for each light-emitting layer to produce different light-emitting colors (for example, white light emission obtained by combining complementary light-emitting colors). Furthermore, a stacked structure in which each light-emitting layer contains different light-emitting substances may be used.

[0172] The light-emitting layers (113, 113a, 113b) may contain one or more organic compounds (host materials, etc.) in addition to the light-emitting substance (guest material). When a plurality of host materials are used in the light-emitting layers (113, 113a, 113b), the light-emitting layers may have the structure described with reference to FIG. 3B in Embodiment 1, for example. In the light-emitting layers, the host material 118 is present in the largest amount by weight, and the guest material 119 is dispersed in the host material 118. The T1 level of the host materials 118 (the first host material 118_1 and the second host material 118_2) in the light-emitting layers is preferably higher than the T1 level of the guest materials (guest material 119).

[0173] As the first host material 118_1, a material having a higher electron transporting property than a hole transporting property can be used. -6 cm 2 Preferably, the material has an electron mobility of 1 / Vs or higher. Examples of materials that readily accept electrons (materials with electron transport properties) include compounds having a π-electron-deficient heteroaromatic ring skeleton, such as nitrogen-containing heteroaromatic compounds, and zinc- or aluminum-based metal complexes. 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- or aluminum-based metal complexes include metal complexes having a quinoline ligand, a benzoquinoline ligand, an oxazole ligand, or a thiazole ligand.

[0174] Specific examples include metal complexes having a quinoline skeleton or a benzoquinoline skeleton, such as tris(8-quinolinolato)aluminum(III) (abbreviation: Alq), tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviation: Almq3), bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq2), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (abbreviation: BAlq), and bis(8-quinolinolato)zinc(II) (abbreviation: Znq). In addition, metal complexes having oxazole- or thiazole-based ligands, such as bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO) and bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ), can also be used. In addition to metal complexes, we have also developed 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 9-[4-(4,5-diphenyl-4H-1,2,4-triazol-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), bathophenanthroline (abbreviation: BPhen), and bathocuproine (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: 2mDBTPDBq-II), and 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II).h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDBTPDBq-II), 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 2-[3-(3,9'-bi-9H-carbazol-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 with a diazine skeleton, such as 3-(dibenzothiophen-4-yl)phenyl]pyrimidine (abbreviated as 4,6mDBTP2Pm-II) and 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviated as 4,6mCzP2Pm), and 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviated as PC Other examples of heterocyclic compounds that can be used include heterocyclic compounds having a triazine skeleton such as 3,5-bis[3-(9H-carbazol-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-methylbenzoxazol-2-yl)stilbene (abbreviated as BzOs). Among the heterocyclic compounds mentioned above, heterocyclic compounds having a triazine skeleton, a diazine (pyrimidine, pyrazine, or pyridazine) skeleton, or a pyridine skeleton are preferred due to their stability and reliability. Furthermore, heterocyclic compounds having such skeletons have high electron transport properties, contributing to reduced driving voltage. In addition, poly(2,5-pyridinediyl) (abbreviation: PPy), poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,Polymer compounds such as poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2'-bipyridine-6,6'-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. -6 cm 2 It is to be noted that any substance other than those mentioned above may be used as long as it has a higher electron transporting property than a hole transporting property.

[0175] The second host material 118_2 is preferably a combination capable of forming an exciplex with the first host material 118_1. Specifically, it preferably has a π-electron-rich heteroaromatic ring or a highly donor skeleton such as 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 so that the emission peak of the exciplex formed by the first host material 118_1 and the second host material 118_2 overlaps with the triplet MLCT (Metal to Ligand Charge Transfer) transition absorption band of the guest material 119, more specifically, the longest wavelength absorption band. This allows for a light-emitting device with significantly improved luminous efficiency. However, when a thermally activated delayed fluorescent material is used as the guest material 119, the longest wavelength absorption band is preferably a singlet absorption band.

[0176] The second host material 118_2 can be a hole-transporting material as follows: -6 cm 2 It is preferable that the hole transport material has a hole mobility of 1 / Vs or more. Specifically, aromatic amines, carbazole derivatives, aromatic hydrocarbons, stilbene derivatives, etc. can be used. The hole transport material may also be a polymer compound.

[0177] Specific examples of these materials with high hole transport properties include aromatic amine compounds such as N,N'-di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), N,N'-bis[4-bis(3-methylphenyl)aminophenyl]-N,N'-diphenyl-4,4'-diaminobiphenyl (abbreviation: DNTPD), and 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B).

[0178] Specific examples of carbazole derivatives include 3-[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA1), 3,6-bis[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA2), and 3,6-bis[N-(4-diphenylaminophenyl)-N-(1-naphthyl)amino]-9-phenylcarbazole (abbreviation: PCzTP N2), 3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2), 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1), and the like can be mentioned.

[0179] Other carbazole derivatives that can be used include 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB), 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA), and 1,4-bis[4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene.

[0180] Examples of aromatic hydrocarbons include 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 2-tert-butyl-9,10-di(1-naphthyl)anthracene, 9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA), 2-tert-butyl-9,10-bis(4-phenylphenyl)anthracene (abbreviation: t-BuDBA), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA), 9,10-diphenylanthracene (abbreviation: DPAnth), 2-tert-butylanthracene (abbreviation: t-BuAnth), 9,10-bis(4-methyl-1-naphthyl)anthracene (abbreviation: DMNA), 2-tert 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, 2,5,8,11-tetra(tert-butyl)perylene, etc. In addition, pentacene, coronene, etc. can also be used. Thus, 1×10 -6 cm 2 It is more preferable to use an aromatic hydrocarbon having a hole mobility of 14 to 42 carbon atoms and having a hole mobility of 14 to 42 carbon atoms.

[0181] The aromatic hydrocarbon may have a vinyl skeleton. Examples of aromatic hydrocarbons having a vinyl skeleton include 4,4'-bis(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi) and 9,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene (abbreviation: DPVPA).

[0182] Alternatively, polymer compounds such as poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphenylamine) (abbreviation: PVTPA), poly[N-(4-{N'-[4-(4-diphenylamino)phenyl]phenyl-N'-phenylamino}phenyl)methacrylamide] (abbreviation: PTPDMA), or poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine] (abbreviation: Poly-TPD) can also be used.

[0183] Furthermore, examples of materials with high hole transport properties include 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-4,4'-diaminobiphenyl (abbreviation: TPD), 4,4',4''-tris(carbazol-9-yl)triphenylamine (abbreviation: TCTA), 4,4',4''-tris[N-(1-naphthyl)-N-phenylamino]triphenylamine (abbreviation: 1'-TNATA), 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′-spirobi[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-spirobi[9H- fluoren]-2-yl)-N,N'N'-triphenyl-1,4-phenylenediamine (abbreviation: DPASF), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-Di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBNBB), 4-phenyldiphenyl-(9-phenyl-9H-carbazol-3-yl)amine (abbreviated as PCA1BP), N,N'-bis(9-phenylcarbazol-3-yl)-N,N'-diphenylbenzene-1,3-diamine (abbreviated as PCA2B), N,N',N''-triphenyl-N,N',N''-tris(9-phenylcarbazol-3-yl)benzene-1,3,5-triamine amine (abbreviation: PCA3B), N-(9,9-diphenyl-9H-fluoren-2-yl)-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: PCAFLP(2)), N-(9,9-diphenyl-9H-fluoren-2-yl)-N,9-diphenyl-9H-carbazol-2-amine (abbreviation: PCAFLP(2)-02), N-(biphenyl-4-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9-phenyl-9H-carbazol-3-amine (abbreviation: PCBiF), N-(biphenyl N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBBiF), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF), N-(9,9-spirobiphenyl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobiphenyl]fluoren-2-amine (abbreviation: PCBASF), Spirobi[9H-fluoren]-2-yl)-N,9-diphenylcarbazol-3-amine (abbreviation: PCASF), N,N'-diphenyl-N,N'-bis(4-diphenylaminophenyl)spirobi[9H-fluorene]-2,7-diamine (abbreviation: DPA2SF), N-[4-(9H-carbazol-9-yl)phenyl]-N-(4-phenyl)phenylaniline (abbreviation: YGA1BP), N,N'-bis[4-(carbazol-9-yl)phenyl]-N,N'-diphenyl-9,9-dimethylfluorene-2,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-carbazol-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 (abbreviation: DBTFLP-III), 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and 4-[3-(triphenylen-2-yl)phenyl]dibenzothiophene (abbreviation: 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, a furan skeleton, a thiophene skeleton, or an aromatic amine skeleton are preferred because of their stability and high reliability. Furthermore, compounds having such skeletons have high hole transport properties and contribute to reduced driving voltage.

[0184] When an organic compound having an electron-transporting property is used as the first host material 118_1 and an organic compound having a hole-transporting property is used as the second host material 118_2, the HOMO level of the organic compound having a hole-transporting property is preferably equal to or higher than the HOMO level of the organic compound having an electron-transporting property. Furthermore, it is preferable that the LUMO level of the organic compound having a hole-transporting property is equal to or higher than the LUMO level of the organic compound having an electron-transporting property, because an exciplex can be formed more efficiently.

[0185] The values ​​of the HOMO level and the LUMO level can be determined by cyclic voltammetry (CV) measurement.

[0186] In cyclic voltammetry (CV) measurements, the values ​​of the HOMO and LUMO levels (E) are determined by the oxidation peak potential (E pa ), and reduction peak potential (E pc ) can be calculated based on the above. In the measurement, the HOMO level can be obtained by scanning the potential in the positive direction, and the LUMO level can be obtained by scanning the potential in the negative direction. The scan rate in the measurement should be 0.1 V / s.

[0187] Specifically, the oxidation peak potential (E pa ), and reduction peak potential (E pc ) to obtain the standard redox potential (E o )(=(E pa +E pc ) / 2) and calculate the potential energy (E x ) to obtain the values ​​of the HOMO and LUMO levels (E) (=E x -E o ) can be calculated respectively.

[0188] The above shows the case where a reversible redox wave is obtained. However, when an irreversible redox wave is obtained, the oxidation peak potential (E pa ) and subtracted a fixed value (0.1 eV) to determine the reduction peak potential (E pc ) and the standard redox potential (E o ) to one decimal place. Also, to calculate the LUMO level, the reduction peak potential (E pc ) plus a certain value (0.1 eV) is taken as the oxidation peak potential (E pa ) and the standard redox potential (E o ) to one decimal place.

[0189] The guest material 119 that can be used in the light-emitting layers (113, 113a, 113b) is not particularly limited, and a light-emitting substance that converts singlet excitation energy into light emission in the visible light region, or a light-emitting substance that converts triplet excitation energy into light emission in the visible light region can be used.

[0190] <Light-emitting material that converts singlet excitation energy into light> Examples of luminescent materials that convert singlet excitation energy into luminescence and can be used in the luminescent layers (113, 113a, 113b) include the following fluorescent substances (fluorescent luminescent materials): 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. Pyrene derivatives are particularly preferred because of their high luminescence quantum yield. Specific examples of pyrene derivatives include N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-bis(dibenzofuran-2-yl)-N,N'-diphenylpyrene-1,6-diamine (abbreviation: 1,6FrAPrn), N,N'-bis(dibenzothiophen-2-yl)-N, N'-diphenylpyrene-1,6-diamine (abbreviation: 1,6ThAPrn), N,N'-(pyrene-1,6-diyl)bis[(N-phenylbenzo[b]naphtho[1,2-d]furan)-6-amine] (abbreviation: 1,6BnfAPrn), N,N'-(pyrene-1,6-diyl)bis[(N-phenylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-02), N,N'-(pyrene-1,6-diyl)bis[(6,N-diphenylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-03), and the like.

[0191] In addition, 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine (abbreviation: PAP2BPy), 5,6-bis[4'-(10-phenyl-9-anthryl)biphenyl-4-yl]-2,2'-bipyridine (abbreviation: PAPP2BPy), N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenyl-4,4'-stilbenediamine (abbreviation: YGA2S), 4-(9H-carbazol-9-yl)phenyl N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), 4-(10-phenyl-9-anthryl)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), 4-(10-phenyl-9-anthryl)-4'- (9-Phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), 4-[4-(10-phenyl-9-anthryl)phenyl]-4'-(9-phenyl-9H-carbazol-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) N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazole-3-amine (abbreviation: 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), and the like can be used.

[0192] In addition, N,N,N',N',N'',N'',N''',N'''-octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), Coumarin 30, N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCAPA), N-[9,10-bis(biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCABPhA), N-(9,10-diphenyl-2-anthryl)-N,N',N'-triphenyl- N-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-carbazol-9-yl)phenyl]-N-phenylanthracen-2-amine (abbreviation: 2YGABPhA), N,N,9-triphenylanthracen-9-amine (abbreviation: DPhAPhA), Coumarin 545T, N,N'-diphenylquinacridone (abbreviation: DP Qd), rubrene, 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]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM2), N,N,N',N'-tetrakis(4-methylphenyl)tetracene-5, 11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviation: p-mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB), 2-(2,6-bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDCM), 2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile Examples of suitable benzofuran dinitrile compounds include N,N'-diphenyl-N,N'-bis(9-phenyl-9H-carbazol-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, pyrene diamine compounds such as 1,6FLPAPrn, 1,6mMemFLPAPrn, and 1,6BnfAPrn-03 can be used.

[0193] In addition, 5,9-diphenyl-5,9-diaza-13b-boranaphtho[3,2,1-de]anthracene (abbreviation: DABNA1), 9-(biphenyl-3-yl)-N,N,5,11-tetraphenyl-5H,9H-[1,4]benzazaborino[2,3,4-kl]phenazaborin-3-amine (abbreviation: DABNA2), 2,12-di(tert-butyl)-5,9-di(4-tert-butylphenyl)-N,N-diphenyl -5H,9H-[1,4]benzazaborino[2,3,4-kl]phenazaborin-7-amine (abbreviation: DPhA-tBu4DABNA), 2,12-di(tert-butyl)-N,N,5,9-tetra(4-tert-butylphenyl)-5H,9H-[1,4]benzazaborino[2,3,4-kl]phenazaborin-7-amine (abbreviation: tBuDPhA-tBu4DABNA), 2,12-di(tert-butyl)-5,9 -Di(4-tert-butylphenyl)-7-methyl-5H,9H-[1,4]benzazaborino[2,3,4-kl]phenazaborine (abbreviation: Me-tBu4DABNA), N7,N7,N13,N13,5,9,11,15-octaphenyl-5H,9H,11H,15H-[1,4]benzazaborino[2,3,4-kl][1,4]benzazaborino[4',3',2':4,5][1,4]benzazaborino[3,2 Nitrogen- and boron-containing condensed heteroaromatic compounds, such as [-b]phenazaborine-7,13-diamine (abbreviation: ν-DABNA) and 2-(4-tert-butylphenyl)benz[5,6]indolo[3,2,1-jk]benzo[b]carbazole (abbreviation: tBuPBibc), in particular compounds with a diaza-boranaphtho-anthracene skeleton, are suitable for use because they have a narrow emission spectrum and can emit blue light with good color purity.

[0194] In addition to these, 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[ Compounds having an indole skeleton such as [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.

[0195] <Light-emitting material that converts triplet excitation energy into light> Next, examples of luminescent materials that can be used in the light-emitting layer 113 and convert triplet excitation energy into luminescence include phosphorescent materials and thermally activated delayed fluorescence (TADF) materials that exhibit thermally activated delayed fluorescence.

[0196] A phosphorescent material is a compound that exhibits phosphorescence but does not exhibit fluorescence at a temperature range from low temperatures (e.g., 77 K) to room temperature (i.e., 77 K to 313 K). The phosphorescent material preferably contains a metal element with a large spin-orbit interaction, such as an organometallic complex, a metal complex (platinum complex), or a rare-earth metal complex. Specifically, a transition metal element is preferred, and a platinum group element (ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), or platinum (Pt)) is particularly preferred. Among these, iridium is preferred because it can increase the transition probability associated with the direct transition between the singlet ground state and the triplet excited state.

[0197] <Phosphorescent materials (400 nm or more but less than 580 nm: blue or green)> Examples of phosphorescent materials that exhibit blue or green light and have an emission spectrum with a peak wavelength of 400 nm or more and less than 580 nm include the following materials.

[0198] 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: organometallic complexes containing a 4H-triazole ring, such as tris[3-(5-biphenyl)-5-isopropyl-4-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviated as [Ir(iPr5btz)3]), tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviated as [Ir(Mptz1-mp)3]), tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviated as [Ir(iPr5btz)3]), Organometallic complexes containing a 1H-triazole ring, such as 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]), and tris(2-{1-[2,6-bis(triazolato)-2-phenyl-1H-imidazole]iridium(III) organometallic complexes with an imidazole ring, such as [(1-methylethyl)phenyl]-1H-imidazol-2-yl-κN}-4-cyanophenyl-κC]iridium(III) (abbreviation: CNImIr), organometallic complexes with a benzimidazolidene skeleton, such as tris[(6-tert-butyl-3-phenyl-2H-imidazo[4,5-b]pyrazin-1-yl-κC)phenyl-κC]iridium(III) (abbreviation: [Ir(cb)3]), and organometallic complexes with a benzimidazolidene skeleton, such as bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’]iridium(III) tetrakis(1-pyrazolyl)borate (abbreviation: FIr6), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]iridium(III) picolinate (abbreviation: FIrpic), bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinato-N,C 2’}iridium(III) picolinate (abbreviation: [Ir(CF3ppy)2(pic)]), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ Examples of suitable complexes include organometallic complexes with phenylpyridine derivatives having electron-withdrawing groups as ligands, such as ]iridium(III) acetylacetonate (abbreviated as FIr(acac)), and platinum complexes such as (2-{3-[3-(3,5-di-tert-butylphenyl)benzimidazol-1-yl-2-ylidene-κC2]phenoxy-κC2}-9-(4-tert-butyl-2-pyridinyl-κN)carbazole-2,1-diyl-κC1)platinum(II) (abbreviated as PtON-TBBI). Compounds in which some of the hydrogen atoms in these compounds have been replaced with deuterium can also be used.

[0199] <Phosphorescent material (490nm or more but less than 590nm: green or yellow)> Examples of phosphorescent materials that exhibit green or yellow color and have an emission spectrum with a peak wavelength of 490 nm or more and less than 590 nm include the following materials.

[0200] For example, tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)3]), tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)3]), (acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)2(acac)]), (acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)2(acac)]), (acetylacetonato)bis[6-(2-norbornyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(tBuppm)2(acac)]), (acetylacetonato)bis[6-(2-norbornyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(nbppm)2(acac)]), (acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(mpmppm )2(acac)]), (acetylacetonato)bis{4,6-dimethyl-2-[6-(2,6-dimethylphenyl)-4-pyrimidinyl-κN3]phenyl-κC}iridium(III) (abbreviation: [Ir(dmppm-dmp)2(acac)]), and (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm)2(acac)]). iridium complexes, organometallic iridium complexes containing a pyrazine ring such as (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-Me)2(acac)]) and (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-iPr)2(acac)]), tris(2-phenylpyridinato-N,C 2’ ) Iridium(III) (abbreviation: [Ir(ppy)3]), bis(2-phenylpyridinato-N,C 2’) Iridium(III) acetylacetonate (abbreviation: [Ir(ppy)2(acac)]), bis(benzo[h]quinolinato)iridium(III) acetylacetonate (abbreviation: [Ir(bzq)2(acac)]), tris(benzo[h]quinolinato)iridium(III) (abbreviation: [Ir(bzq)3]), tris(2-phenylquinolinato-N,C 2’ ) Iridium(III) (abbreviation: [Ir(pq)3]), bis(2-phenylquinolinato-N,C 2’) 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)benzofuro[2,3-b]pyridine-κC]bis[2-(5-d3-methyl {2-(methyl-d3)-8-[4-(1-methylethyl-1-d)-2-pyridinyl-κN]benzofuro[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-d3)2(mbfpypy-d3)), {2-(methyl-d3)-8-[4-(1-methylethyl-1-d)-2-pyridinyl-κN]benzofuro[2,3-b]pyridin-7-yl-κC}bis{5-(methyl-d3)-2-[5-(methyl-d3)-2-pyridinyl-κN]phenyl-κC}iridium(III) (abbreviation: Ir(5mtpy-d6)2(mbfpypy-iPr-d4)), [2-d3-methyl-(2-pyridinyl-κN)benzofuro[2,3-b]pyridin-7-yl-κC] [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 Organometallic iridium complexes containing a pyridine ring, such as [Ir(5mppy-d3)2(mdppy-d3)], [2-methyl-(2-pyridinyl-κN)benzofuro[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]pyridinato-N,C 2’}Iridium(III) acetylacetonate (abbreviation: [Ir(p-PF-ph)2(acac)]), bis(2-phenylbenzothiazolato-N,C 2’ ) iridium(III) acetylacetonate (abbreviated as [Ir(bt)2(acac)]), as well as rare earth metal complexes such as tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviated as [Tb(acac)3(Phen)]), (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 [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)phenolato-κO]platinum(II) (abbreviation: Pt(4tButpppypyp-mmtBup)). Compounds in which some of the hydrogen atoms in these compounds are replaced with deuterium atoms can also be used.

[0201] <Phosphorescent materials (570 nm or more but less than 750 nm: yellow or red)> Examples of phosphorescent materials that exhibit yellow or red color and have an emission spectrum with a peak wavelength of 570 nm or more and less than 750 nm include the following materials.

[0202] For example, pyrimidinato]iridium(III) such as (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III) (abbreviation: [Ir(5mdppm)2(dibm)]), bis[4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(5mdppm)2(dpm)]), and (dipivaloylmethanato)bis[4,6-di(naphthalen-1-yl)pyrimidinato]iridium(III) (abbreviation: [Ir(d1npm)2(dpm)]). Organometallic complexes containing an imidine 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)]), and bis{4,6-dimethyl-2-[3-(3,5-dimethylphenyl)-5-phenyl-2-pyrazinyl-κN]phenyl-κC}(2,6-dimethyl-3,5-heptanedionato-κN). 2 O,O')iridium(III) (abbreviation: [Ir(dmdppr-P)2(dibm)]), bis{4,6-dimethyl-2-[5-(4-cyano-2,6-dimethylphenyl)-3-(3,5-dimethylphenyl)-2-pyrazinyl-κN]phenyl-κC}(2,2,6,6-tetramethyl-3,5-heptanedionato-κ) 2 O,O')iridium(III) (abbreviation: [Ir(dmdppr-dmCP)2(dpm)]), 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’)iridium(III) (abbreviation: [Ir(dpq)2(acac)]), organometallic complexes with a pyrazine ring such as (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: [Ir(Fdpq)2(acac)]), 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 containing 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 of suitable complexes include platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum(II) (abbreviation: [PtOEP]), and rare earth metal complexes such as tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III) (abbreviation: [Eu(DBM)3(Phen)]), and tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III) (abbreviation: [Eu(TTA)3(Phen)]). Compounds in which some of the hydrogen atoms in these compounds have been replaced with deuterium atoms can also be used.

[0203] ≪TADF material≫ The following materials can be used as TADF materials. TADF materials are materials that have a small difference between the S1 level and the T1 level (preferably 0.20 eV or less), can upconvert a triplet excited state to a singlet excited state with a small amount of thermal energy (reverse intersystem crossing), and efficiently emit light (fluorescence) from the singlet excited state. 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. Delayed fluorescence in TADF materials refers to light emission that has a spectrum similar to that of normal fluorescence but has a significantly long lifetime. Its lifetime is 1×10 -6 seconds or more, or 1×10 -3 More than a second.

[0204] The TADF material can also be used as an electron transporting material, a hole transporting material, or a host material.

[0205] Examples of TADF materials include fullerene and its derivatives, acridine derivatives such as proflavine, eosin, etc. Also included are metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd). Examples of metal-containing porphyrins include protoporphyrin-tin fluoride complex (abbreviation: SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (abbreviation: SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (abbreviation: SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (abbreviation: SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (abbreviation: SnF2(OEP)), etioporphyrin-tin fluoride complex (abbreviation: SnF2(Etio I)), and octaethylporphyrin-platinum chloride complex (abbreviation: PtCl2OEP).

[0206] [ka]

[0207] Other examples include 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 2-[4-(10H-phenoxazole) 3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), bis[4-(9,9- Dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), 10-phenyl-10H,10'H-spiro[acridine-9,9'-anthracen]-10'-one (abbreviation: ACRSA), 4-(9'-phenyl-[3,3'-bi-9H-carbazol]-9-yl)benzofuro[3,2-d]pyrimidine (abbreviation: 4PCCzBfpm), 4-[4-(9'-phenyl-[3,3'- Heteroaromatic compounds having a π-electron rich heteroaromatic compound and a π-electron deficient heteroaromatic compound, such as 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9′-phenyl-2,3′-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), may also be used.

[0208] In addition, a substance in which a π-electron-rich heteroaromatic compound and a π-electron-deficient heteroaromatic compound are directly bonded is particularly preferable because the donor property of the π-electron-rich heteroaromatic compound and the acceptor property of the π-electron-deficient heteroaromatic compound are both strong, thereby reducing the energy difference between the singlet excited state and the triplet excited state. Furthermore, a TADF material (TADF100) in which the singlet excited state and the triplet excited state are in thermal equilibrium may also be used as the TADF material. Such TADF materials have a short emission lifetime (excitation lifetime), which can suppress efficiency decline in light-emitting devices in the high-brightness range.

[0209] [ka]

[0210] In addition to the above, examples of materials capable of converting triplet excitation energy into luminescence include nanostructures of transition metal compounds having a perovskite structure. Nanostructures of metal halide perovskites are particularly preferred. Nanoparticles and nanorods are preferred as such nanostructures.

[0211] The light-emitting layer 113 can also be configured with 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 this order from the hole-transporting layer side, a substance having hole-transporting properties may be used as a host material for the first light-emitting layer, and a substance having electron-transporting properties may be used as a host material for the second light-emitting layer. The light-emitting materials of the first light-emitting layer and the second light-emitting layer may be the same or different, and may be materials that emit light of the same color or different colors. By using light-emitting materials that emit light of different colors in the two light-emitting layers, multiple light emissions can be obtained simultaneously. In particular, it is preferable to select light-emitting materials for each light-emitting layer so that the light emitted by the two light-emitting layers becomes white.

[0212] The light-emitting layer 113 may contain materials other than the host material 118 and the guest material 119 .

[0213] The light-emitting layer 113 can be formed by a vapor deposition method (including a vacuum deposition method), an inkjet method, a coating method, gravure printing, etc. In addition to the materials described above, the light-emitting layer 113 may contain inorganic compounds such as quantum dots or polymer compounds (oligomers, dendrimers, polymers, etc.).

[0214] <Hole injection layer> The hole injection layer (111, 111a, 111b) is a layer that injects holes from the first electrode 101, which functions as an anode, and the charge generation layer (106, 106a, 106b) into the organic compound layer (103, 103a, 103b), and is a layer that contains an organic acceptor material and a material with high hole injection properties.

[0215] The hole injection layer (111, 111a, 111b) functions to promote hole injection by reducing the hole injection barrier from one of the pair of electrodes (the first electrode 101 or the second electrode 102). It is formed, for example, from a transition metal oxide, a phthalocyanine derivative, or an aromatic amine. Examples of transition metal oxides include molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, and manganese oxide. Examples of phthalocyanine derivatives include phthalocyanine and metal phthalocyanine. Examples of aromatic amines include benzidine derivatives and phenylenediamine derivatives. Polymer compounds such as polythiophene and polyaniline can also be used. A typical example is poly(ethylenedioxythiophene) / polystyrene sulfonic acid, which is a self-doped polythiophene.

[0216] The hole-injection layers (111, 111a, 111b) may be layers containing a composite material of a hole-transporting material and a material exhibiting electron-accepting properties. Alternatively, a stack of a layer containing an electron-accepting material and a layer containing a hole-transporting material may be used. Charges can be transferred between these materials in a steady state or under the presence of an electric field. Examples of electron-accepting materials include organic acceptors such as quinodimethane derivatives, chloranil derivatives, and hexaazatriphenylene derivatives. Specific examples include compounds having an electron-withdrawing group (halogen or cyano group), 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). Alternatively, transition metal oxides, such as oxides of metals from Groups 4 to 8, can be used. Specific examples 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 air, has low hygroscopicity, and is easy to handle.

[0217] As the hole transporting material, a material having a higher hole transporting property than electron transporting property can be used. -6 cm 2 It is preferable that the material has a hole mobility of 1 / Vs or more. Specifically, aromatic amines, carbazole derivatives, aromatic hydrocarbons, stilbene derivatives, and the like, which are listed as hole-transporting materials that can be used for the light-emitting layer 113, can be used. The hole-transporting material may also be a polymer compound.

[0218] <Hole transport layer> The hole transport layers (112, 112a, 112b) are layers containing a hole transport material, and the hole transport materials exemplified as the material for the hole injection layers (111, 111a, 111b) can be used. The hole transport layers (112, 112a, 112b) have the function of transporting holes injected into the hole injection layers (111, 111a, 111b) to the light-emitting layers (113, 113a, 113b), and therefore preferably have a HOMO level that is the same as or close to the HOMO level of the hole injection layers (111, 111a, 111b).

[0219] The hole transport material is 1×10 -6 cm 2 It is preferable that the material has a hole mobility of 1 / Vs or more. However, other materials may be used as long as they have a higher hole transporting property than electron transporting property. Note that the layer containing the material with a high hole transporting property may be a single layer or may be a stack of two or more layers made of the above material.

[0220] ≪Electron transport layer≫ The electron transport layers (114, 114a, 114b) have a function of transporting electrons injected from the other of the pair of electrodes (the first electrode 101 or the second electrode 102) through the electron injection layers (115, 115a, 115b) to the light-emitting layer 113. As the electron transport material, a material having a higher electron transporting property than a hole transporting property can be used, and the electron transporting property is 1×10 -6 cm 2 / Vs or more. As a compound that easily accepts electrons (a material having electron transport properties), a compound having a π-electron-deficient heteroaromatic ring skeleton such as a nitrogen-containing heteroaromatic compound, or a metal complex, etc. can be used. Specific examples include metal complexes having a quinoline ligand, a benzoquinoline ligand, an oxazole ligand, or a thiazole ligand, which are listed as electron transport materials that can be used in the light-emitting layer 113. Other examples include oxadiazole derivatives, triazole derivatives, benzimidazole derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, phenanthroline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, and triazine derivatives. The electron transport materials can have a conductivity of 1×10-6 cm 2 It is preferable that the electron transport layer is a substance having an electron mobility of 1 / Vs or higher. Note that other substances may be used as the electron transport layer as long as they have a higher electron transporting property than hole transporting property. The electron transport layer (114, 114a, 114b) may be a single layer or a stack of two or more layers made of the above substances.

[0221] Furthermore, a layer for controlling the movement of electron carriers may be provided between the electron transport layer (114, 114a, 114b) and the light-emitting layer (113, 113a, 113b). This layer is made by adding a small amount of a substance with high electron trapping properties to a material with high electron transport properties as described above, and by suppressing the movement of electron carriers, it becomes possible to adjust the carrier balance. Such a configuration is highly effective in suppressing problems (e.g., a reduction in device life) caused by electrons passing through the light-emitting layer.

[0222] ≪Electron injection layer≫ The electron injection layer (115, 115a, 115b) has a function of promoting electron injection by reducing the electron injection barrier from the second electrode 102, and can be made of, for example, a Group 1 metal, a Group 2 metal, or an oxide, halide, or carbonate thereof. Also, a composite material of the above-mentioned electron transport material and a material that exhibits electron donating properties can be used. Examples of materials that exhibit electron donating properties include Group 1 metals, Group 2 metals, or oxides thereof. Specific examples include lithium fluoride (LiF), sodium fluoride (NaF), cesium fluoride (CsF), calcium fluoride (CaF2), and lithium oxide (LiO xAlkali metals, alkaline earth metals, or compounds thereof such as fluoride (ErF3) can be used. Rare earth metal compounds such as erbium fluoride (ErF3) can also be used. Electrides can also be used for the electron injection layer 115. Examples of such electrides include a substance in which a high concentration of electrons is added to a mixed oxide of calcium and aluminum. Materials that can be used for the electron transport layers (114, 114a, 114b) can also be used for the electron injection layers (115, 115a, 115b).

[0223] Alternatively, the electron injection layer (115, 115a, 115b) may be formed using a composite material obtained by mixing an organic compound and an electron donor (donor). Such composite materials have excellent electron injection and transport properties because electrons are generated in the organic compound by the electron donor. In this case, the organic compound is preferably a material that is excellent in transporting the generated electrons. Specifically, for example, the materials (metal complexes, heteroaromatic compounds, etc.) that constitute the second carrier transport layer 117 and the electron transport layer 114 of the aforementioned stacked-type light-emitting device may be used. The electron donor may be any material 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 preferred, such as lithium oxide, calcium oxide, and barium oxide. Lewis bases, such as magnesium oxide, may also be used. In addition, organic compounds such as tetrathiafulvalene (abbreviation: TTF) can also be used.

[0224] Furthermore, a material having strong basicity may be used for the electron injection layers (115, 115a, 115b). Specific examples of strongly basic materials include 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 (abbreviation: 2hppSF), 2,9-bis(1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidin-1-yl)-1,10-phenanthroline (abbreviation: 2,9hpp2Phen), 4,7-di-1-pyrrolidinyl-1,10-phenanthroline (abbreviation: Pyrrd-Phen), and 8,8'-pyridine-2,6-diyl-bis(5,6,7,8-tetrahydroimidazo[1,2-a]pyrimidine) (abbreviation: 2,6tip2Py).

[0225] In a forward-stacked light-emitting device, the light-emitting layer is preferably formed by a vapor deposition method (including a vacuum deposition method), and the hole injection layer, hole transport layer, electron transport layer, and electron injection layer can each be formed by a vapor deposition method (including a vacuum deposition method), an inkjet method, a coating method, a gravure printing method, or the like. In a reverse-stacked light-emitting device, the light-emitting layer can be formed by a vapor deposition method (including a vacuum deposition method), an inkjet method, a coating method, a gravure printing method, or the like, and the hole injection layer, hole transport layer, electron transport layer, and electron injection layer are preferably formed by a vapor deposition method (including a vacuum deposition method). In addition to the above-mentioned materials, the light-emitting layer, hole injection layer, hole transport layer, electron transport layer, and electron injection layer may also use inorganic compounds such as quantum dots or polymeric compounds (oligomers, dendrimers, polymers, etc.).

[0226] Quantum dots may be colloidal quantum dots, alloy quantum dots, core-shell quantum dots, core quantum dots, etc. Quantum dots containing elements from groups 2 and 16, 13 and 15, 13 and 17, 11 and 17, or 14 and 15 may also be used. 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 also be used.

[0227] <Pair of electrodes> The first electrode 101 and the second electrode 102 function as an anode or a cathode of the light-emitting device. The first electrode 101 and the second electrode 102 can be formed using a metal, an alloy, a conductive compound, or a mixture or stack of these materials.

[0228] It is preferable that one of the first electrode 101 and the second electrode 102 is formed of a conductive material that has a light-reflecting function. Examples of the conductive material include aluminum (Al) and alloys containing Al. Examples of alloys containing Al include alloys containing Al and L (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. Furthermore, aluminum is abundant in the earth's crust and inexpensive, so the use of aluminum can reduce the production costs of light-emitting devices. Alternatively, silver (Ag) or an alloy containing Ag and N (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 alloys containing silver 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 that can be used include tungsten, chromium (Cr), molybdenum (Mo), copper, and titanium.

[0229] Furthermore, light emitted from the light-emitting layer is extracted through one or both of the first electrode 101 and the second electrode 102. Therefore, at least one of the first electrode 101 and the second electrode 102 is preferably formed from a conductive material that has a light-transmitting function. The conductive material has a visible light transmittance of 40% or more and 100% or less, preferably 60% or more and 100% or less, and a resistivity of 1×10 -2 Examples include conductive materials with a resistance of Ω·cm or less.

[0230] The first electrode 101 and the second electrode 102 may be formed of a conductive material that has both a light transmitting 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 -2 Examples of suitable conductive materials include those with a resistivity of Ω·cm or less. For example, the conductive layer can be formed using one or more conductive metals, alloys, conductive compounds, etc. Specifically, metal oxides such as indium tin oxide (ITO), indium tin oxide containing silicon or silicon oxide (abbreviated as ITSO), indium zinc oxide, titanium-containing indium tin oxide, indium titanium oxide, and indium oxide containing tungsten oxide and zinc oxide can be used. Alternatively, a thin metal film that is light-transmitting (preferably, a thickness of 1 nm to 30 nm) can be used. Examples of suitable metals include Ag, and alloys such as Ag and Al, Ag and Mg, Ag and Au, and Ag and Yb.

[0231] 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 is conductive, and includes, for example, oxide conductors such as ITO as described above, as well as oxide semiconductors or organic conductors containing organic substances. Examples of organic conductors containing organic substances include composite materials obtained by mixing an organic compound with an electron donor (donor), and composite materials obtained by mixing an organic compound with an electron acceptor. In addition, inorganic carbon-based materials such as graphene may also be used. The resistivity of the material is preferably 1×10 5 Ω·cm or less, more preferably 1×10 4 Ω·cm or less.

[0232] Alternatively, one or both of the first electrode 101 and the second electrode 102 may be formed by stacking a plurality of the above materials.

[0233] Furthermore, in order to improve light extraction efficiency, a material having a higher refractive index than an electrode having a light-transmitting function may be formed in contact with the electrode. Such a material may be any material that transmits visible light, and may or may not be conductive. Examples of such a material include oxide semiconductors and organic materials, as well as the oxide conductors described above. Examples of organic materials include the materials exemplified for the light-emitting layer, hole injection layer, hole transport layer, electron transport layer, and electron injection layer. Inorganic carbon-based materials or thin metal films that transmit light may also be used, and multiple layers of several nanometers to several tens of nanometers thick may be stacked.

[0234] When the first electrode 101 or the second electrode 102 functions as a cathode, it is preferable that the electrode be made of a material with a small work function (3.8 eV or less). For example, elements belonging to Group 1 or 2 of the periodic table (alkali metals such as lithium, sodium, and cesium, alkaline earth metals such as calcium and strontium, magnesium, etc.), alloys containing these elements (e.g., Ag and Mg, Al and Li), rare earth metals such as europium (Eu) and Yb, alloys containing these rare earth metals, alloys containing aluminum and silver, etc. can be used.

[0235] When the first electrode 101 or the second electrode 102 is used as an anode, it is preferable to use a material with a large work function (4.0 eV or more).

[0236] The first electrode 101 and the second electrode 102 may be a laminate of a conductive material having a light-reflecting function and a conductive material having a light-transmitting function. In this case, the first electrode 101 and the second electrode 102 are preferable because they can adjust the optical path so that light of a desired wavelength from each light-emitting layer can be resonated and the light of that wavelength can be intensified.

[0237] The first electrode 101 and the second electrode 102 can be formed by any suitable method, such as sputtering, vapor deposition, printing, coating, MBE (Molecular Beam Epitaxy), CVD (Chemical Vapor Deposition), pulsed laser deposition, or ALD (Atomic Layer Deposition).

[0238] <Charge generation layer> The charge generation layer 106 has a function of injecting electrons into the organic compound layer 103a and injecting 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 a structure in which an electron acceptor is added to a hole transporting material (also referred to as a P-type layer), or a structure in which an electron donor is added to an electron transporting material (also referred to as an electron injection buffer layer). Alternatively, both of these structures may be stacked. Furthermore, 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 above-mentioned materials, it is possible to suppress an increase in driving voltage when organic compound layers are stacked.

[0239] When the charge generation layer 106 has a structure in which an electron acceptor is added to a hole-transporting material that is an organic compound (a P-type layer), the material described in this embodiment can be used as the hole-transporting material. Examples of the electron acceptor include 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ) and chloranil. Examples of the electron acceptor include oxides of metals that belong to Groups 4 to 8 of the periodic table. Specific examples include vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, and rhenium oxide. The acceptor materials described above may also be used. Materials for the P-type layer may be mixed together to form a mixed film, or single films containing each material may be stacked.

[0240] When the charge generation layer 106 has a structure in which an electron donor is added to an electron transporting material (electron injection buffer layer), the material described in this embodiment can be used as the electron transporting material. The electron donor can be an alkali metal, an alkaline earth metal, a rare earth metal, or a metal belonging to Groups 2 and 13 of the periodic table, or an oxide or carbonate thereof. Specifically, lithium (Li), cesium (Cs), magnesium (Mg), calcium (Ca), ytterbium (Yb), indium (In), lithium oxide (LiO), cesium carbonate, or the like is preferably used. An organic compound such as tetrathianaphthacene can also be used as the electron donor.

[0241] When an electron relay layer is provided between the P-type layer and the electron injection buffer layer in the charge generation layer 106, the electron relay layer contains at least a substance having electron transport properties and has the function of preventing interaction between the electron injection buffer layer and the P-type layer and smoothly transferring electrons. The LUMO level of the substance having electron transport properties contained in the electron relay layer is preferably between the LUMO level of the acceptor substance in the P-type layer and the LUMO level of the substance having electron transport properties contained in the electron transport layer in contact with the charge generation layer 106. The specific energy level of the LUMO level of the substance having electron transport properties used in the electron relay layer is −5.0 eV or higher, preferably −5.0 eV or higher and −3.0 eV or lower. Note that the substance having electron transport properties used in the electron relay layer is preferably a phthalocyanine-based material or a metal complex having a metal-oxygen bond and an aromatic ligand.

[0242] Although FIG. 4D shows a structure in which two organic compound layers 103 are stacked, a stack structure of three or more organic compound layers may be used by providing a charge generation layer between different organic compound layers.

[0243] <Cap layer> Although not shown in FIGS. 4A to 4E, a capping 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 capping layer. By providing the capping layer on the second electrode 102, the extraction efficiency of light emitted from the second electrode 102 can be improved.

[0244] 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 (abbreviation: BisBTc) and 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II).

[0245] <Substrate> The light-emitting device according to one embodiment of the present invention may be fabricated over a substrate made of glass, plastic, or the like. The order of fabrication on the substrate may be from the first electrode 101 side or from the second electrode 102 side.

[0246] Note that, as a substrate on which a light-emitting device according to one embodiment 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, and examples thereof include a plastic substrate made of polycarbonate or polyarylate. Films, inorganic vapor-deposited films, and the like can also be used. Note that other materials may be used as long as they function as a support in the manufacturing process of the light-emitting device and the optical element. Alternatively, any material may be used as long as it has a function of protecting the light-emitting device and the optical element.

[0247] For example, in this specification, a light-emitting device can be formed using various substrates. The type of substrate is not particularly limited. Examples of such 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, and base films. Examples of glass substrates include barium borosilicate glass, aluminoborosilicate glass, and soda-lime glass. Examples of flexible substrates, laminated films, and base films include the following: plastics such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), and polytetrafluoroethylene (PTFE). Another example is acrylic resin. Another example is polypropylene, polyester, polyvinyl fluoride, or polyvinyl chloride. Other examples include resins such as polyamide resin, polyimide resin, aramid resin, and epoxy resin, inorganic vapor deposition films, and papers.

[0248] Alternatively, a flexible substrate may be used as the substrate, and the light-emitting device may be formed directly on the flexible substrate. Alternatively, 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 entirely completed and 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 may be, for example, a laminated structure of inorganic films such as a tungsten film and a silicon oxide film, or a structure in which a resin film such as polyimide is formed on a substrate.

[0249] That is, a light-emitting device may be formed using a certain substrate, and then the light-emitting device may be transferred to another substrate, and the light-emitting device may be disposed on the other substrate. In addition to the substrates mentioned above, examples of the substrate onto which the light-emitting device may be transferred include a cellophane substrate, a stone substrate, a wood substrate, a cloth substrate (including natural fibers (silk, cotton, linen), synthetic fibers (nylon, polyurethane, polyester), or recycled fibers (acetate, cupra, rayon, recycled polyester)), a leather substrate, or a rubber substrate. By using these substrates, a light-emitting device that is durable, highly heat-resistant, lightweight, or thin can be obtained.

[0250] Alternatively, a field effect transistor (FET) may be formed on the substrate, and a light-emitting device may be fabricated on an electrode electrically connected to the FET, thereby producing an active matrix display device in which the FET controls the driving of the light-emitting device.

[0251] The structure described in this embodiment mode can be used in appropriate combination with structures described in other embodiments.

[0252] (Embodiment 3) 5B, a display device is formed by forming a plurality of light-emitting devices 130 over an insulating layer 175. In this embodiment, a display device according to one embodiment of the present invention will be described in detail.

[0253] The display device 100 has a pixel section 177 in which a plurality of pixels 178 are arranged in a matrix. The pixel 178 has a sub-pixel 110R, a sub-pixel 110G, and a sub-pixel 110B.

[0254] In this specification and the like, when describing matters common to, for example, the subpixels 110R, 110G, and 110B, they may be referred to as the subpixels 110. When describing matters common to other components distinguished by alphabets, they may also be described using symbols without the alphabets.

[0255] The sub-pixel 110R emits red light, the sub-pixel 110G emits green light, and the sub-pixel 110B emits blue light. This allows an image to be displayed in the pixel unit 177. In this embodiment, sub-pixels of three colors, red (R), green (G), and blue (B), are described as an example, but combinations of sub-pixels of other colors may also be used. The number of sub-pixels is not limited to three, and may be four or more. Examples of four sub-pixels include sub-pixels of four colors: R, G, B, and white (W); sub-pixels of four colors: R, G, B, and yellow (Y); and sub-pixels of R, G, B, and infrared (IR).

[0256] In this specification, the row direction may be referred to as the X direction, and the column direction may be referred to as the Y direction. The X direction and the Y direction intersect, for example, perpendicularly.

[0257] 5A shows an example in which sub-pixels of different colors are arranged side by side in the X direction, and sub-pixels of the same color are arranged side by side in the Y direction. Note that sub-pixels of different colors may also be arranged side by side in the Y direction, and sub-pixels of the same color may also be arranged side by side in the X direction.

[0258] A connection portion 140 may be provided outside the pixel portion 177, and a region 141 may be provided. The region 141 is provided between the pixel portion 177 and the connection portion 140. The region 141 is provided with an organic compound layer 103. Furthermore, the connection portion 140 is provided with a conductive layer 151C.

[0259] 5A shows an example in which the region 141 and the connection portion 140 are located on the right side of the pixel portion 177, but the positions of the region 141 and the connection portion 140 are not particularly limited. The region 141 and the connection portion 140 may be singular or plural.

[0260] Fig. 5(B) is an example of a cross-sectional view taken along dashed line A1-A2 in Fig. 5(A). As shown in Fig. 5(A), the display device 100 includes 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, the insulating layer 174, and the insulating layer 173 have openings that reach the conductive layer 172, and a plug 176 is provided to fill the opening.

[0261] In the pixel section 177, the light-emitting device 130 is provided on the insulating layer 175 and the plug 176. A protective layer 135 is provided to cover the light-emitting device 130. The 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.

[0262] 5B shows multiple cross sections of the inorganic insulating layer 125 and the insulating layer 127, it is preferable that the inorganic insulating layer 125 and the insulating layer 127 are connected to one another when the display device 100 is viewed from above. That is, it is preferable that the inorganic insulating layer 125 and the insulating layer 127 are insulating layers having openings above the first electrodes.

[0263] 5(B) shows light emitting device 130R, light emitting device 130G, and light emitting device 130B. Light emitting device 130R, light emitting device 130G, and light emitting device 130B emit light of different colors. 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. Light emitting device 130R, light emitting device 130G, or light emitting device 130B may also emit other visible light or infrared light.

[0264] The display device of one embodiment of the present invention can be, for example, a top-emission type that emits light in the direction opposite to the substrate on which the light-emitting device is formed. Note that the display device of one embodiment of the present invention may also be a bottom-emission type.

[0265] Examples of the light-emitting material contained in the light-emitting device 130 include organic compounds or organometallic complexes such as fluorescent materials, phosphorescent materials, and thermally activated delayed fluorescence (TADF) materials. Furthermore, the light-emitting material may also be an inorganic compound such as quantum dots.

[0266] The light-emitting device 130R has the configuration described in Embodiment 1. It includes a first electrode (pixel electrode) composed 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 inclusion is preferred because it reduces damage to the organic compound layer 103R during processing. When the common layer 104 is provided, it is preferred that the common layer 104 be an electron injection layer. When the common layer 104 is not provided, the organic compound layer 103R corresponds to the organic compound layer 103 in Embodiments 1 and 2. When the common layer 104 is provided, the stacked structure of the organic compound layer 103R and the common layer 104 corresponds to the organic compound layer 103 in Embodiments 1 and 2.

[0267] The light-emitting device 130G has the same configuration as that described in Embodiment 1. It includes a first electrode (pixel electrode) including 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 inclusion is preferred because it reduces damage to the organic compound layer 103G during processing. When the common layer 104 is not provided, the organic compound layer 103G corresponds to the organic compound layer 103 in Embodiments 1 and 2. When the common layer 104 is provided, the stacked structure of the organic compound layer 103G and the common layer 104 corresponds to the organic compound layer 103 in Embodiments 1 and 2.

[0268] The light-emitting device 130B has the same configuration as that described in Embodiment 1. It includes a first electrode (pixel electrode) including 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 inclusion is preferred because it reduces damage to the organic compound layer 103B during processing. When the common layer 104 is not provided, the organic compound layer 103B corresponds to the organic compound layer 103 in Embodiments 1 and 2. When the common layer 104 is provided, the stacked structure of the organic compound layer 103B and the common layer 104 corresponds to the organic compound layer 103 in Embodiments 1 and 2.

[0269] One of the pixel electrode and the common electrode of the light-emitting device functions as an anode and the other functions as a cathode. In the following description, unless otherwise specified, the pixel electrode functions as an anode and the common electrode functions as a cathode.

[0270] The organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B are independent island-shaped layers for each light-emitting device or for each emitted color. By providing the organic compound layer 103 in an island shape for each light-emitting device 130, leakage current between adjacent light-emitting devices 130 can be suppressed even in a high-resolution display device. This makes it possible to prevent crosstalk and realize a display device with extremely high contrast. In particular, a display device with high current efficiency at low brightness can be realized.

[0271] The island-shaped organic compound layer 103 is formed by depositing an EL film and processing the EL film using a lithography method.

[0272] In the display device of one embodiment of the present invention, the first electrode (pixel electrode) of the light-emitting device preferably has a stacked structure. For example, in the example shown in FIG. 5B, the first electrode of the light-emitting device 130 has a stacked structure of conductive layers 151 (151R, 151G, and 151B) and conductive layers 152 (152R, 152G, and 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 has high reflectivity for visible light and the conductive layer 152 has transparency to visible light and a high 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 extraction efficiency of light emitted from the organic compound layer 103. When the pixel electrode functions as an anode, the higher the work function of the pixel electrode, the easier it is to inject holes into the organic compound layer 103. As described above, by forming the pixel electrode of the light-emitting device 130 into a laminated structure of the conductive layer 151 having a high reflectivity for visible light and the conductive layer 152 having a high work function, the light-emitting device 130 can be a light-emitting device with a high light extraction efficiency and a low driving voltage. Note that in this specification and the like, when describing matters common to the conductive layer 151R, the conductive layer 151G, and the conductive layer 151B, they may be referred to as the conductive layer 151.

[0273] When the conductive layer 151 is a layer having high reflectance to visible light, the reflectance of the conductive layer 151 to visible light is preferably, for example, 40% to 100%, or 70% to 100%. When the conductive layer 152 is an electrode that is transparent to visible light, the transmittance of the conductive layer 152 to visible light is preferably, for example, 40% or more.

[0274] Here, when the pixel electrode has a laminated structure made up of multiple layers, the pixel electrode may be altered due to, for example, a reaction between the multiple layers. For example, when a film formed after forming the pixel electrode is removed by a wet etching method, galvanic corrosion may occur when a chemical solution comes into contact with the pixel electrode.

[0275] Therefore, in the display device 100 of the present embodiment, insulating layers 156 (156R, 156G, 156B) are formed on the side surfaces of the conductive layers 151 and 152. This prevents a chemical solution from coming into contact with the conductive layer 151, even when a film formed after forming a pixel electrode having the conductive layers 151 and 152 is removed by wet etching. This prevents, for example, galvanic corrosion from occurring in the pixel electrode. The display device 100 can therefore be manufactured using a method with a high yield, resulting in a low-cost display device. Furthermore, since defects in the display device 100 can be prevented, the display device 100 can be made highly reliable. In this specification and the like, when describing matters common to the insulating layers 156R, 156G, and 156B, they may be referred to as the insulating layer 156.

[0276] For example, a metal material can be used for 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), etc., and alloys containing appropriate combinations of these metals can also be used.

[0277] The conductive layer 152 can be formed using an oxide containing one or more selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon. For example, it is preferable to use a conductive oxide containing one or more of 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, and therefore can be suitably used for the conductive layer 152.

[0278] The conductive layer 151 may have a stacked structure of multiple layers containing different materials, and the conductive layer 152 may have a stacked structure of multiple layers containing different materials. In this case, the conductive layer 151 may include a layer containing a material that can be used for the conductive layer 152, such as a conductive oxide, or the conductive layer 152 may include a layer containing a material that can be used for the conductive layer 151, such as a metal material. For example, when the conductive layer 151 has a stacked structure of two or more layers, a layer in contact with the conductive layer 152 can be a layer containing a material that can be used for the conductive layer 152.

[0279] The structure of this embodiment can be used in appropriate combination with structures of other embodiments.

[0280] (Fourth embodiment) In this embodiment, a light-emitting device of one embodiment of the present invention will be described with reference to FIGS. 6A to 6G and 7A to 7I.

[0281] [Pixel layout] In this embodiment, pixel layouts different from that shown in Fig. 5(A) will be mainly described. There are no particular limitations on the arrangement of sub-pixels, and various methods can be applied. Examples of sub-pixel arrangements include a stripe arrangement, an S-stripe arrangement, a matrix arrangement, a delta arrangement, a Bayer arrangement, and a pentile arrangement.

[0282] The top shape of the sub-pixels shown in the drawings in this embodiment mode corresponds to the top shape of the light-emitting region.

[0283] The top surface shape of the subpixel may be, for example, a triangle, a quadrangle (including a rectangle and a square), a polygon such as a pentagon, a polygon with rounded corners, an ellipse, or a circle.

[0284] Furthermore, the layout of the circuits constituting the sub-pixels is not limited to the range of the sub-pixels shown in the drawings, and may be arranged outside of the range.

[0285] An S-stripe arrangement is applied to the pixel 178 shown in Fig. 6(A). The pixel 178 shown in Fig. 6(A) is composed of three subpixels: a subpixel 110R, a subpixel 110G, and a subpixel 110B.

[0286] The pixel 178 shown in FIG. 6B includes a subpixel 110R having a generally trapezoidal or triangular top surface shape with rounded corners, a subpixel 110G having a generally trapezoidal or triangular top surface shape with rounded corners, and a subpixel 110B having a generally rectangular or hexagonal top surface shape with rounded corners. The subpixel 110R has a larger light-emitting area than the subpixel 110G. Thus, the shape and size of each subpixel can be determined independently. For example, the more reliable the light-emitting device, the smaller the size of the subpixel.

[0287] The Pentile arrangement is applied to the pixels 124a and 124b shown in Fig. 6(C). Fig. 6(C) shows an example in which the pixel 124a having the subpixel 110R and the subpixel 110G and the pixel 124b having the subpixel 110G and the subpixel 110B are arranged alternately.

[0288] 6(D) to 6(F) are arranged in a delta configuration. Pixel 124a has two subpixels (subpixel 110R and subpixel 110G) in the top row (first row) and one subpixel (subpixel 110B) in the bottom row (second row). Pixel 124b has one subpixel (subpixel 110B) in the top row (first row) and two subpixels (subpixel 110R and subpixel 110G) in the bottom row (second row).

[0289] Figure 6(D) is an example in which each sub-pixel has an approximately rectangular top surface shape with rounded corners, Figure 6(E) is an example in which each sub-pixel has a circular top surface shape, and Figure 6(F) is an example in which each sub-pixel has an approximately hexagonal top surface shape with rounded corners.

[0290] In FIG. 6(F), each subpixel is arranged inside a densely arranged hexagonal region. Each subpixel is arranged so that 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 to surround it.

[0291] 6G shows an example in which subpixels of each color are arranged in a zigzag pattern. Specifically, when viewed from above, the positions of the upper sides of two subpixels aligned in the row direction (for example, subpixels 110R and 110G, or subpixels 110G and 110B) are misaligned.

[0292] 6(A) to 6(G), it is preferable that the subpixel 110R is the subpixel R that emits red light, the subpixel 110G is the subpixel G that emits green light, and the subpixel 110B is the subpixel B that emits blue light. Note that the configuration of the subpixels is not limited to this, and the colors that the subpixels emit and their arrangement order can be determined appropriately. For example, the subpixel 110G may be the subpixel R that emits red light, and the subpixel 110R may be the subpixel G that emits green light.

[0293] In photolithography, the finer the pattern to be processed, the more significant the effect of light diffraction becomes. This impairs the fidelity of the photomask pattern when it is transferred by exposure, making it difficult to process the resist mask into the desired shape. Therefore, even if the photomask pattern is rectangular, a pattern with rounded corners is likely to be formed. As a result, the top surface shape of the subpixel may become a polygon with rounded corners, an ellipse, a circle, or the like.

[0294] 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 material for the organic compound layer and the curing temperature of the resist material, the resist film may not be cured sufficiently. A resist film that is not cured sufficiently may have a shape that is different from the desired shape during processing. As a result, the top surface shape of the organic compound layer may be a polygon with rounded corners, an ellipse, a circle, or the like. For example, when a resist mask with a square top surface shape is formed, a resist mask with a circular top surface shape may be formed, resulting in a circular top surface shape of the organic compound layer.

[0295] In order to form the top surface of the organic compound layer into a desired shape, a technique for correcting the mask pattern in advance (OPC (Optical Proximity Correction) technique) may be used so that the design pattern and the transfer pattern coincide with each other. Specifically, in the OPC technique, a correction pattern is added to, for example, the corners of the figure on the mask pattern.

[0296] As shown in FIGS. 7A to 7I, a pixel can have four types of subpixels.

[0297] The pixels 178 shown in FIGS. 7(A) to 7(C) are arranged in a stripe pattern.

[0298] Figure 7(A) is an example in which each subpixel has a rectangular top surface shape, Figure 7(B) is an example in which each subpixel has a top surface shape that is a combination of two semicircles and a rectangle, and Figure 7(C) is an example in which each subpixel has an elliptical top surface shape.

[0299] The pixels 178 shown in FIGS. 7(D) to 7(F) are arranged in a matrix.

[0300] Figure 7(D) is an example in which each sub-pixel has a square top surface shape, Figure 7(E) is an example in which each sub-pixel has an approximately square top surface shape with rounded corners, and Figure 7(F) is an example in which each sub-pixel has a circular top surface shape.

[0301] 7(G) and 7(H) show an example in which one pixel 178 is configured in two rows and three columns.

[0302] 7(G) has three subpixels (subpixel 110R, subpixel 110G, and subpixel 110B) in the top row (first row) and one subpixel (subpixel 110W) in the bottom row (second row). In other words, pixel 178 has subpixel 110R in the left column (first column), subpixel 110G in the center column (second column), subpixel 110B in the right column (third column), and subpixel 110W across these three columns.

[0303] The pixel 178 shown in FIG. 7(H) has three subpixels (subpixels 110R, 110G, and 110B) in the top row (first row) and three subpixels 110W in the bottom row (second row). In other words, the pixel 178 has subpixels 110R and 110W in the left column (first column), subpixels 110G and 110W in the center column (second column), and subpixels 110B and 110W in the right column (third column). By aligning the subpixels in the top and bottom rows as shown in FIG. 7(H), it becomes possible to efficiently remove dust that may occur during the manufacturing process. Therefore, a light-emitting device with high display quality can be provided.

[0304] In the pixel 178 shown in FIGS. 7(G) and 7(H), the subpixels 110R, 110G, and 110B are laid out in a stripe arrangement, which can improve the display quality.

[0305] FIG. 7(I) shows an example in which one pixel 178 is configured in three rows and two columns.

[0306] 7(I) has subpixel 110R in the top row (first row), subpixel 110G in the middle row (second row), subpixel 110B across the first and second rows, and one subpixel (subpixel 110W) in the bottom row (third row). In other words, pixel 178 has subpixel 110R and subpixel 110G in the left column (first column), subpixel 110B in the right column (second column), and subpixel 110W across these two columns.

[0307] In the pixel 178 shown in FIG. 7(I), the layout of the subpixels 110R, 110G, and 110B is a so-called S-stripe arrangement, which can improve the display quality.

[0308] 7A to 7I, the pixel 178 is composed of four subpixels: subpixel 110R, subpixel 110G, subpixel 110B, and subpixel 110W. For example, the subpixel 110R may be a subpixel that emits red light, the subpixel 110G may be a subpixel that emits green light, the subpixel 110B may be a subpixel that emits blue light, and the subpixel 110W may be a subpixel that emits white light. Note that at least one of the 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.

[0309] As described above, in the light-emitting device of one embodiment of the present invention, various layouts can be applied to pixels each including a subpixel having a light-emitting device.

[0310] This embodiment mode can be combined with other embodiment modes or examples as appropriate. In addition, in this specification, when multiple configuration examples are shown in one embodiment mode, the configuration examples can be combined as appropriate.

[0311] (Embodiment 5) In this embodiment, a light-emitting device according to one embodiment of the present invention will be described.

[0312] The light emitting device of the present embodiment can be a high-definition light emitting device, and therefore can be used for the display unit of a wristwatch-type or bracelet-type information terminal (wearable device), a head-mounted display (HMD) or other VR device, and a head-mounted wearable device such as a glasses-type AR device.

[0313] The light-emitting device of this embodiment can be a high-resolution light-emitting device or a large-sized light-emitting device. Therefore, the light-emitting device of this embodiment can be used in the display portion of electronic devices having relatively large screens, such as television sets, desktop or notebook personal computers, computer monitors, digital signage, and large game machines such as pachinko machines, as well as digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, personal digital assistants, and sound reproducing devices.

[0314] [Display module] 8A shows a perspective view of a display module 280. The display module 280 includes a display device 100A and an FPC 290. Note that the light-emitting device included in the display module 280 is not limited to the display device 100A, and may be any of display devices 100B to 100F described later.

[0315] The display module 280 has a substrate 291 and a substrate 292. The display module 280 has a display unit 281. The display unit 281 is a region that displays an image in the display module 280, and is a region where light from each pixel provided in a pixel unit 284 (described later) can be viewed.

[0316] 8(B) is a perspective view schematically showing the configuration on the substrate 291 side. A circuit portion 282, a pixel circuit portion 283 on the circuit portion 282, and a pixel portion 284 on the pixel circuit portion 283 are stacked on the substrate 291. A terminal portion 285 for connecting to an FPC 290 is provided in a portion of the substrate 291 that does not overlap with the pixel portion 284. The terminal portion 285 and the circuit portion 282 are electrically connected by a wiring portion 286 composed of a plurality of wirings.

[0317] The pixel section 284 has a plurality of periodically arranged pixels 284a. An enlarged view of one pixel 284a is shown on the right side of Fig. 8(B). The various configurations described in the previous embodiments can be applied to the pixel 284a. Fig. 8(B) shows an example in which the pixel 284a has the same configuration as the pixel 178 shown in Fig. 5(A).

[0318] The pixel circuit section 283 has a plurality of pixel circuits 283a arranged periodically.

[0319] One pixel circuit 283a is a circuit that controls the driving of multiple elements included in one pixel 284a. One pixel circuit 283a can be configured to have three circuits that control the light emission of one light-emitting device. For example, the 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 light-emitting device.

[0320] The circuit portion 282 includes a circuit for driving each pixel circuit 283a of the pixel circuit portion 283. For example, it is preferable that the circuit portion 282 includes one or both of a gate line driver circuit and a source line driver circuit. In addition, the circuit portion 282 may include at least one of an arithmetic circuit, a memory circuit, a power supply circuit, and the like.

[0321] The FPC 290 functions as wiring for supplying a video signal, a power supply potential, or the like from the outside to the circuit section 282. An IC may be mounted on the FPC 290.

[0322] The display module 280 can be configured such that one or both of the pixel circuit unit 283 and the circuit unit 282 are stacked below the pixel unit 284, thereby enabling the aperture ratio (effective display area ratio) of the display unit 281 to be extremely high. For example, the aperture ratio of the display unit 281 can be set to 40% or more and less than 100%, preferably 50% or more and 95% or less, and more preferably 60% or more and 95% or less. Furthermore, the pixels 284a can be arranged at an extremely high density, enabling the resolution of the display unit 281 to be extremely high. For example, it is preferable that the pixels 284a are arranged in the display unit 281 at a resolution of 2000 ppi or more, preferably 3000 ppi or more, more preferably 5000 ppi or more, and even more preferably 6000 ppi or more, and 20000 ppi or less, or 30000 ppi or less.

[0323] Such a display module 280 has extremely high resolution and can therefore be suitably used in VR devices such as HMDs or eyeglass-type AR devices. For example, even in a configuration in which the display unit of the display module 280 is viewed through lenses, the display module 280 has an extremely high-resolution display unit 281, so that even when the display unit is enlarged with lenses, the pixels are not visible, allowing for a highly immersive display. Furthermore, the display module 280 is not limited to this, and can be suitably used in electronic devices having relatively small display units. For example, it can be suitably used in the display unit of a wearable electronic device such as a wristwatch.

[0324] [Display device 100A] The display device 100A shown in FIG. 9A includes a substrate 301, a light emitting device 130R, a light emitting device 130G, a light emitting device 130B, a capacitor 240, and a transistor 310.

[0325] The substrate 301 corresponds to the substrate 291 in FIGS. 8A and 8B. The transistor 310 is a transistor having a channel formation region in the substrate 301. The substrate 301 can be, for example, a semiconductor substrate such as a single crystal silicon substrate. The transistor 310 includes a part of the substrate 301, a conductive layer 311, a low-resistance region 312, an insulating layer 313, and an insulating layer 314. The conductive layer 311 functions as a gate electrode. The insulating layer 313 is located between the substrate 301 and the conductive layer 311 and functions as a gate insulating layer. The low-resistance region 312 is a region in which the substrate 301 is doped with impurities and functions as a source or drain. The insulating layer 314 is provided to cover a side surface of the conductive layer 311.

[0326] Furthermore, an element isolation layer 315 is provided between two adjacent transistors 310 so as to be embedded in the substrate 301 .

[0327] In addition, an insulating layer 261 is provided to cover the transistor 310 , and a capacitor 240 is provided on the insulating layer 261 .

[0328] Capacitor 240 has conductive layer 241, conductive layer 245, and insulating layer 243 located therebetween. Conductive layer 241 functions as one electrode of capacitor 240, conductive layer 245 functions as the other electrode of capacitor 240, and insulating layer 243 functions as a dielectric of capacitor 240.

[0329] The conductive layer 241 is provided over the insulating layer 261 and is buried in the insulating layer 254. The conductive layer 241 is electrically connected to one of the source and drain of the transistor 310 by a plug 271 buried in the insulating layer 261. The insulating layer 243 is provided to cover the conductive layer 241. The conductive layer 245 is provided in a region overlapping with the conductive layer 241 with the insulating layer 243 interposed therebetween.

[0330] An insulating layer 255 is provided to cover the capacitor 240, an insulating layer 174 is provided on the insulating layer 255, and an insulating layer 175 is provided on the insulating layer 174. The light-emitting device 130R, the light-emitting device 130G, and the light-emitting device 130B are provided on the insulating layer 175. FIG. 9A shows an example in which the light-emitting device 130R, the light-emitting device 130G, and the light-emitting device 130B have the layered structure shown in FIG. 1A. An insulator is provided in the region between adjacent light-emitting devices. For example, in FIG. 9A, an inorganic insulating layer 125 and an insulating layer 127 on the inorganic insulating layer 125 are provided in this region.

[0331] Insulating layer 156R is provided to have a region overlapping with a side surface of conductive layer 151R of light-emitting device 130R, insulating layer 156G is provided to have a region overlapping with a side surface of conductive layer 151G of light-emitting device 130G, and insulating layer 156B is provided to have a region overlapping with a side surface of conductive layer 151B of light-emitting device 130B. Furthermore, conductive layer 152R is provided to cover conductive layer 151R and insulating layer 156R, conductive layer 152G is provided to cover conductive layer 151G and insulating layer 156G, and conductive layer 152B is provided to cover conductive layer 151B and 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.

[0332] The conductive layer 151R, the conductive layer 151G, and the conductive layer 151B are electrically connected to one of the source or drain of the transistor 310 via an insulating layer 243, an insulating layer 255, an insulating layer 174, 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 the same or approximately the same. Various conductive materials can be used for the plug.

[0333] 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 via a resin layer 122. For details of the components from the light-emitting devices 130 to the substrate 120, refer to embodiment 3. The substrate 120 corresponds to the substrate 292 in FIG. 8(A).

[0334] 9(B) is a modified example of the display device 100A shown in FIG. 9(A). The light-emitting device shown in FIG. 9(B) has a colored layer 136R, a colored layer 136G, and a colored layer 136B, and the light-emitting device 130 has an area where it overlaps with one of the colored layers 136R, 136G, and 136B. In the light-emitting device shown in FIG. 9(B), 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.

[0335] [Display device 100B] FIG. 10 shows a perspective view of the display device 100B, and FIG. 11(A) shows a cross-sectional view of the display device 100B.

[0336] The display device 100B has a configuration in which a substrate 352 and a substrate 351 are bonded together. In Fig. 10, the substrate 352 is clearly indicated by a dashed line.

[0337] The display device 100B has a pixel portion 177, a connection portion 140, a circuit 356, wiring 355, etc. Fig. 10 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 Fig. 10 can also be called a display module having the display device 100B, an IC, and an FPC. Here, a light-emitting device having a connector such as an FPC attached to a substrate, or a light-emitting device having an IC mounted on the substrate, is called a display module.

[0338] The connection portion 140 is provided outside the pixel portion 177. The connection portion 140 can be provided along one side or multiple sides of the pixel portion 177. There may be one or multiple connection portions 140. FIG. 10 shows an example in which the connection portion 140 is provided so as to surround the four sides of the pixel portion 177. The connection portion 140 electrically connects the common electrode of the light-emitting device and the conductive layer, and can supply a potential to the common electrode.

[0339] The circuit 356 can be, for example, a scanning line driver circuit.

[0340] The wiring 355 has a function of supplying signals and power to the pixel portion 177 and the circuit 356. The signals and power are input to the wiring 355 from the outside via the FPC 353 or from the IC 354.

[0341] 10 shows an example in which an IC 354 is provided on a substrate 351 by a COG (Chip On Glass) method or a COF (Chip On Film) method. The IC 354 may be, for example, an IC having a scanning line driver circuit or a signal line driver circuit. The display device 100B and the display module may not include an IC. Alternatively, the IC may be mounted on an FPC by, for example, a COF method.

[0342] Figure 11(A) shows an example of a cross section of the display device 100B, where a portion of the region 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 region including the end portion are cut.

[0343] The display device 100B shown in Figure 11(A) has, between a substrate 351 and a substrate 352, 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.

[0344] The light emitting devices 130R, 130G, and 130B each have the layered structure shown in Fig. 1A, except that the configuration of the pixel electrodes is different. For details of the light emitting devices, refer to the above embodiment.

[0345] Light-emitting device 130R includes conductive layer 224R, conductive layer 151R on conductive layer 224R, and conductive layer 152R on conductive layer 151R. Light-emitting device 130G includes conductive layer 224G, conductive layer 151G on conductive layer 224G, and conductive layer 152G on conductive layer 151G. Light-emitting device 130B includes conductive layer 224B, conductive layer 151B on conductive layer 224B, and conductive layer 152B on conductive layer 151B. Here, conductive layer 224R, conductive layer 151R, and conductive layer 152R may collectively be referred to as the pixel electrode of light-emitting device 130R, and conductive layer 151R and conductive layer 152R excluding conductive layer 224R may also be referred to as the pixel electrode of light-emitting device 130R. Similarly, conductive layer 224G, conductive layer 151G, and conductive layer 152G may be collectively referred to as the pixel electrode of light-emitting device 130G, and conductive layer 151G and conductive layer 152G excluding conductive layer 224G may be collectively referred to as the pixel electrode of light-emitting device 130G. Furthermore, conductive layer 224B, conductive layer 151B, and conductive layer 152B may be collectively referred to as the pixel electrode of light-emitting device 130B, and conductive layer 151B and conductive layer 152B excluding conductive layer 224B may be collectively referred to as the pixel electrode of light-emitting device 130B.

[0346] The conductive layer 224R is connected to the conductive layer 222b of the transistor 205 through an opening provided in the insulating layer 214. An end of the conductive layer 151R is located outside an end of the conductive layer 224R. An insulating layer 156R is provided to have a region in contact with a side surface of the conductive layer 151R, and a conductive layer 152R is provided to cover the conductive layer 151R and the insulating layer 156R.

[0347] Conductive layer 224G, conductive layer 151G, conductive layer 152G, and insulating layer 156G in light-emitting device 130G, and conductive layer 224B, conductive layer 151B, conductive layer 152B, and insulating layer 156B in light-emitting device 130B are similar to conductive layer 224R, conductive layer 151R, conductive layer 152R, and insulating layer 156R in light-emitting device 130R, and therefore detailed description thereof will be omitted.

[0348] Recesses are formed in the conductive layers 224R, 224G, and 224B so as to cover the openings provided in the insulating layer 214. A layer 128 is buried in the recesses.

[0349] Layer 128 has the function of planarizing the recesses of conductive layer 224R, conductive layer 224G, and conductive layer 224B. Conductive layers 151R, 151G, and 151B, which are electrically connected to conductive layer 224R, conductive layer 224G, and conductive layer 224B, are provided on conductive layer 224R, conductive layer 224G, and conductive layer 224B and layer 128. Therefore, the regions overlapping with the recesses of conductive layer 224R, conductive layer 224G, and conductive layer 224B can also be used as light-emitting regions, thereby increasing the aperture ratio of the pixel.

[0350] The 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 the layer 128 as appropriate. In particular, the layer 128 is preferably formed using an insulating material, and is particularly preferably formed using an organic insulating material. For example, the organic insulating materials that can be used for the insulating layer 127 described above can be used for the layer 128.

[0351] A protective layer 135 is provided on the light-emitting device 130R, the light-emitting device 130G, and the light-emitting device 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 sealing structure, a hollow sealing structure, or the like can be applied to seal the light-emitting device 130. In FIG. 11(A), the space between the substrate 352 and the substrate 351 is filled with the adhesive layer 142, and a solid sealing structure is applied. Alternatively, the space may be filled with an inert gas (nitrogen, argon, etc.), and a hollow sealing structure may be applied. In this case, the adhesive layer 142 may be provided so as not to overlap with the light-emitting device. Alternatively, the space may be filled with a resin different from the frame-shaped adhesive layer 142.

[0352] 11A shows an example in which the connection portion 140 has a conductive layer 224C obtained by processing the same conductive film as the conductive layers 224R, 224G, and 224B, a conductive layer 151C obtained by processing the same conductive film as the conductive layers 151R, 151G, and 151B, and a conductive layer 152C obtained by processing the same conductive film as the conductive layers 152R, 152G, and 152B. Also, FIG. 11A shows an example in which an insulating layer 156C is provided so as to have a region overlapping with a side surface of the conductive layer 151C.

[0353] The display device 100B is a top-emission type. Light emitted by the light-emitting device is emitted toward the substrate 352. The substrate 352 is preferably made of a material that is highly transparent to visible light. The pixel electrodes contain a material that reflects visible light, and the counter electrode (common electrode 155) contains a material that transmits visible light.

[0354] The transistor 201 and the transistor 205 are both formed over a substrate 351. These transistors can be manufactured using the same material and the same process.

[0355] An insulating layer 211, an insulating layer 213, an insulating layer 215, and an insulating layer 214 are provided over the substrate 351 in this order. A part of the insulating layer 211 functions as a gate insulating layer for each transistor. A part of the insulating layer 213 functions as a gate insulating layer for each transistor. The insulating layer 215 is provided to cover the transistor. The insulating layer 214 is provided to cover the transistor and functions as a planarization layer. Note that the number of gate insulating layers and the number of insulating layers covering the transistors are not limited, and each may be a single layer or two or more layers.

[0356] It is preferable that at least one insulating layer covering the transistor is made of a material that is resistant to the diffusion of impurities such as water and hydrogen. This allows the insulating layer to function as a barrier layer. With this structure, it is possible to effectively prevent impurities from diffusing into the transistor from the outside, thereby improving the reliability of the light-emitting device.

[0357] It is preferable to use an inorganic insulating film for each of the insulating layers 211, 213, and 215. Examples of the inorganic insulating film that can be used include a silicon nitride film, a silicon oxynitride film, a silicon oxide film, a silicon nitride oxide film, an aluminum oxide film, and an aluminum nitride film. Alternatively, a hafnium oxide film, an yttrium oxide film, a zirconium oxide film, a gallium oxide film, a tantalum oxide film, a magnesium oxide film, a lanthanum oxide film, a cerium oxide film, and a neodymium oxide film may also be used. Two or more of the above insulating films may be stacked.

[0358] An organic insulating layer is suitable for the insulating layer 214, which functions as a planarizing layer. Materials that can be used for the organic insulating layer include acrylic resin, polyimide resin, epoxy resin, polyamide resin, polyimideamide resin, siloxane resin, benzocyclobutene-based resin, phenolic 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 prevents recesses from being formed in the insulating layer 214 during processing of the conductive layer 224R, the conductive layer 151R, the conductive layer 152R, or the like. Alternatively, recesses may be formed in the insulating layer 214 during processing of the conductive layer 224R, the conductive layer 151R, the conductive layer 152R, or the like.

[0359] The transistor 201 and the transistor 205 each include 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 a source and a 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.

[0360] The structure of the transistor included in the light-emitting device of this embodiment is not particularly limited. For example, a planar transistor, a staggered transistor, an inverted staggered transistor, or the like can be used. Furthermore, either a top-gate transistor or a bottom-gate transistor structure may be used. Alternatively, gates may be provided above and below a semiconductor layer in which a channel is formed.

[0361] The transistor 201 and the transistor 205 have a structure in which a semiconductor layer in which a channel is formed is sandwiched between two gates. The two gates may be connected and the same signal may be supplied to drive the transistor. Alternatively, the threshold voltage of the transistor may be controlled by applying a potential for controlling the threshold voltage to one of the two gates and a potential for driving to the other.

[0362] The crystallinity of a semiconductor material used for a transistor is not particularly limited, and any of an amorphous semiconductor and a crystalline semiconductor (a microcrystalline semiconductor, a polycrystalline semiconductor, a single crystal semiconductor, or a semiconductor having a crystalline region in part) may be used. The use of a crystalline semiconductor is preferable because it can suppress deterioration of transistor characteristics.

[0363] A semiconductor layer of the transistor preferably contains a metal oxide. That is, the light-emitting device of this embodiment preferably uses a transistor using a metal oxide in a channel formation region (hereinafter referred to as an OS transistor).

[0364] Examples of crystalline oxide semiconductors include c-axis-aligned crystalline (CAAC)-OS and nanocrystalline (nc)-OS.

[0365] Alternatively, a transistor using silicon in a channel formation region (Si transistor) may be used. Examples of silicon include single crystal silicon, polycrystalline silicon, and amorphous silicon. In particular, a transistor having low temperature polysilicon (LTPS) in a semiconductor layer (hereinafter also referred to as an LTPS transistor) may be used. LTPS transistors have high field-effect mobility and good frequency characteristics.

[0366] By using Si transistors such as LTPS transistors, circuits that need to be driven at high frequencies (such as source driver circuits) can be built on the same substrate as the display unit, which simplifies the external circuits mounted on the light-emitting device and reduces component and mounting costs.

[0367] OS transistors have significantly higher field-effect mobility than transistors using amorphous silicon. Furthermore, OS transistors have significantly lower source-drain leakage current in the off state and can retain charge accumulated in a capacitor connected in series with the transistor for a long period of time. Furthermore, the use of OS transistors can reduce the power consumption of light-emitting devices.

[0368] Furthermore, to increase the emission luminance of a light-emitting device included in a 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. Because OS transistors have a higher source-drain breakdown voltage than Si transistors, a high 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 a pixel circuit, it is possible to increase the amount of current flowing through the light-emitting device and increase the emission luminance of the light-emitting device.

[0369] Furthermore, in terms of the saturation characteristics of the current that flows when the transistor operates in the saturation region, OS transistors can pass 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 drive transistor, a stable current can be passed through a light-emitting device, even when the current-voltage characteristics of the light-emitting device vary. In other words, when operating in the saturation region, the source-drain current of an OS transistor remains almost unchanged even when the source-drain voltage increases, thereby stabilizing the light-emitting brightness of the light-emitting device.

[0370] As described above, by using an OS transistor as a driving transistor included in a pixel circuit, it is possible to achieve "suppression of black floating," "increase in light emission brightness," "multiple gradations," and "suppression of variations in light-emitting devices."

[0371] The semiconductor layer preferably contains, for example, indium, M (wherein M is one or more elements selected from gallium, aluminum, silicon, boron, yttrium, tin, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium), and zinc. In particular, M is preferably one or more elements selected from aluminum, gallium, yttrium, and tin.

[0372] In particular, it is preferable to use an oxide containing indium (In), gallium (Ga), and zinc (Zn) (also referred to as IGZO) for 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 referred to as IAZO). Alternatively, it is preferable to use an oxide containing indium (In), aluminum (Al), gallium (Ga), and zinc (Zn) (also referred to as IAGZO). Alternatively, it is preferable to use an oxide containing indium (In) (also referred to as IO).

[0373] When the semiconductor layer is an In-M-Zn oxide, the atomic ratio of In in the In-M-Zn oxide is preferably equal to or greater than the atomic ratio of M. Examples of atomic ratios of metal elements in such In-M-Zn oxides include In:M:Zn=1:1:1 or a composition thereabout, In:M:Zn=1:1:1.2 or a composition thereabout, In:M:Zn=2:1:3 or a composition thereabout, In:M:Zn=3:1:2 or a composition thereabout, In:M:Zn=4:2:3 or a composition thereabout, In:M:Zn=4:2:4.1 or a composition thereabout, In:M:Zn=5:1:3 or a composition thereabout, In:M:Zn=5:1:6 or a composition thereabout, In:M:Zn=5:1:7 or a composition thereabout, In:M:Zn=5:1:8 or a composition thereabout, In:M:Zn=6:1:6 or a composition thereabout, and In:M:Zn=5:2:5 or a composition thereabout. The term "nearby composition" includes a range of ±30% of the desired atomic ratio.

[0374] When describing an atomic ratio of In:Ga:Zn=4:2:3 or thereabout, this includes a case where, when In is taken as 4, Ga is 1 to 3 and Zn is 2 to 4. When describing an atomic ratio of In:Ga:Zn=5:1:6 or thereabout, this includes a case where, when In is taken as 5, Ga is more than 0.1 to 2 and Zn is more than 5 to 7. When describing an atomic ratio of In:Ga:Zn=1:1:1 or thereabout, this includes a case where, when In is taken as 1, Ga is more than 0.1 to 2 and Zn is more than 0.1 to 2.

[0375] The transistors included in the circuit 356 and the transistors included in the pixel portion 177 may have the same structure or different structures. The transistors included in the circuit 356 may all have the same structure or may have two or more types. Similarly, the transistors included in the pixel portion 177 may all have the same structure or may have two or more types.

[0376] All the transistors included in the pixel portion 177 may be OS transistors, all the transistors included in the pixel portion 177 may be Si transistors, or some of the transistors included in the pixel portion 177 may be OS transistors and the rest may be Si transistors.

[0377] For example, by using both an LTPS transistor and an OS transistor in the pixel portion 177, a light-emitting device with low power consumption and high driving capability can be realized. A configuration in which an LTPS transistor and an OS transistor are combined is sometimes called LTPO. It is preferable to use an OS transistor as a transistor that functions as a switch for controlling the conduction / non-conduction of wiring, and an LTPS transistor as a transistor for controlling current.

[0378] For example, one of the transistors included in the pixel portion 177 functions as a transistor for controlling the current flowing through the light-emitting device and can be called a driving transistor. One of the source and drain of the driving transistor is electrically connected to the pixel electrode of the light-emitting device. It is preferable to use an LTPS transistor as the driving transistor. This allows the current flowing through the light-emitting device in the pixel circuit to be increased.

[0379] On the other hand, another transistor in the pixel portion 177 functions as a switch for controlling pixel selection / deselection and can also be called a selection transistor. The gate of the selection transistor is electrically connected to a gate line, and one of the source and drain is electrically connected to a source line (signal line). It is preferable to use an OS transistor as the selection transistor. This allows the gradation of the pixel to be maintained even when the frame frequency is significantly reduced (for example, 1 fps or less), so power consumption can be reduced by stopping the driver when displaying a still image.

[0380] As described above, the light-emitting device of one embodiment of the present invention can have a high aperture ratio, high definition, high display quality, and low power consumption.

[0381] Note that a light-emitting device according to one embodiment of the present invention includes an OS transistor and a light-emitting device with an MML (metal maskless) structure. This structure can significantly reduce leakage current that may flow through the transistor and leakage current that may flow between adjacent light-emitting devices (also referred to as lateral leakage current). Furthermore, with this structure, when an image is displayed on the light-emitting device, a viewer can observe one or more of image clarity, image sharpness, high saturation, and a high contrast ratio. Note that a structure in which leakage current that may flow through the transistor and lateral leakage current between light-emitting devices are extremely low can minimize light leakage during black display (so-called floating black).

[0382] In particular, among light-emitting devices with an MML structure, by applying the SBS (Side By Side) structure, which is a structure in which the light-emitting layers are made differently or painted differently as described above, the layers provided between the light-emitting devices (for example, organic layers shared between the light-emitting devices, also called common layers) are configured to be separated, thereby eliminating or greatly reducing side leakage.

[0383] 11B and 11C show other structural examples of the transistor.

[0384] The transistor 209 and the transistor 210 each include a conductive layer 221 functioning as a gate, an insulating layer 211 functioning as a gate insulating layer, a semiconductor layer 231 including a channel formation 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 functioning as a gate insulating layer, a conductive layer 223 functioning 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 formation region 231i. The insulating layer 225 is located at least between the conductive layer 223 and the channel formation region 231i. An insulating layer 218 covering the transistor may also be provided.

[0385] 11B shows an example in which the insulating layer 225 covers the top surface and side surfaces of the semiconductor layer 231. The conductive layer 222a and the conductive layer 222b are connected to the low-resistance region 231n through openings provided in the insulating layer 225 and the insulating layer 215, respectively. One of the conductive layer 222a and the conductive layer 222b functions as a source, and the other functions as a drain.

[0386] 11C, 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 insulating layer 225 is processed using the conductive layer 223 as a mask, so that the structure shown in FIG. 11C can be manufactured. In FIG. 11C, the insulating layer 215 is provided to cover the insulating layer 225 and the conductive layer 223, and the conductive layer 222a and the conductive layer 222b are connected to the low-resistance region 231n through openings in the insulating layer 215.

[0387] A connection portion 204 is provided in a region of the substrate 351 where the substrate 352 does not overlap. In the connection portion 204, a wiring 355 is electrically connected to the FPC 353 via a conductive layer 166 and a connection layer 242. The conductive layer 166 has an example of a laminated structure including a conductive film obtained by processing the same conductive film as the conductive layers 224R, 224G, and 224B, a conductive film obtained by processing the same conductive film as the conductive layers 151R, 151G, and 151B, and a conductive film obtained by processing the same conductive film as the conductive layers 152R, 152G, and 152B. The conductive layer 166 is exposed on the upper surface of the connection portion 204. This allows the connection portion 204 and the FPC 353 to be electrically connected via the connection layer 242.

[0388] It is preferable to provide a light-shielding layer 157 on the surface of the substrate 352 facing the substrate 351. The light-shielding layer 157 can be provided between adjacent light-emitting devices, on the connection section 140, on the circuit 356, etc. Also, various optical members can be arranged on the outside of the substrate 352.

[0389] The substrate 351 and the substrate 352 can be made of the same material as can be used for the substrate 120 .

[0390] The adhesive layer 142 can be made of a material that can be used for the resin layer 122 .

[0391] The connection layer 242 may be an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), or the like.

[0392] [Display device 100C] The display device 100C shown in FIG. 12 differs from the display device 100B shown in FIG. 11(A) mainly in that it is a bottom-emission light-emitting device.

[0393] Light emitted from the light emitting device is emitted toward the substrate 351. It is preferable that a material with high transparency to visible light is used for the substrate 351. On the other hand, the light transparency of the material used for the substrate 352 is not an issue.

[0394] 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 12 shows an example in which the light-shielding layer 157 is provided over the substrate 351, the insulating layer 153 is provided over the light-shielding layer 157, and the transistors 201, 205, etc. are provided over the insulating layer 153.

[0395] Light emitting device 130R includes conductive layer 112R, conductive layer 126R on conductive layer 112R, and conductive layer 129R on conductive layer 126R.

[0396] Light emitting device 130B includes conductive layer 112B, conductive layer 126B on conductive layer 112B, and conductive layer 129B on conductive layer 126B.

[0397] The conductive layers 112R, 112B, 126R, 126B, 129R, and 129B are made of a material that is highly transparent to visible light. The common electrode 155 is preferably made of a material that reflects visible light.

[0398] Although the light emitting device 130G is not shown in FIG. 12, the light emitting device 130G is also provided.

[0399] In addition, although FIG. 12 and other figures show an example in which the top surface of the layer 128 has a flat portion, the shape of the layer 128 is not particularly limited.

[0400] [Display device 100D] The display device 100D shown in Fig. 13 is a bottom-emission type, but is an example of a bottom-emission type display device that differs from the display device 100C shown in Fig. 12. The display device 100D differs from the display device 100C in that it has an organic resin layer 180. Note that in the figure, the reference numerals of the same components as those in Fig. 12 may be omitted, and the description in Fig. 12 may be referred to for details.

[0401] 13(B) shows a top view layout of pixel 178 (pixel 178a and pixel 178b) having subpixels 110 (subpixels 110R, 110G, 110B, and 110W), and FIG. 13(C) shows a top view of organic resin layer 180 in a region where subpixels 110R and 110W of pixel 178 are formed. Note that the distance between light-shielding layers 317 is width 110Rw in the light-emitting region of subpixel 110R.

[0402] As shown in FIG. 13(A), the organic resin layer 180 is provided on the insulating layer 214. As shown in the region surrounded by the dashed line in FIG. 13(A) and in FIG. 13(C), the organic resin layer 180 has curved recesses 181 (recesses 181a and 181b) at least in the region where the subpixels are formed. The recesses 181 may be provided outside the light-emitting region, such as recess 181c. By providing recess 181c, light emitted in the region overlapping with the light-shielding layer 317 or light traveling to the region overlapping with the light-shielding layer 317 is refracted and can be extracted from the light-emitting region, thereby improving the light-emitting efficiency.

[0403] A plurality of recesses 181 may be formed in a matrix. Recesses 181a and 181b may be provided in contact with each other, or may have a flat surface between them.

[0404] 13(A) and 13(C), the recess has a hexagonal top surface shape (FIG. 13(C)) and a semicircular cross-sectional shape (FIG. 13(A)), but may have other shapes as needed. For example, the recess may have a polygonal top surface shape such as a triangle, a quadrangle (including a rectangle and a square), a pentagon, or any other polygon with rounded corners, an ellipse, or a circle.

[0405] An insulating layer containing an organic material can be used as the organic resin layer 180. For example, acrylic resin, polyimide resin, epoxy resin, imide resin, polyamide resin, polyimideamide resin, silicone resin, siloxane resin, benzocyclobutene resin, phenol resin, precursors of these resins, etc. can be used as the organic resin layer 180. Alternatively, organic materials such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or alcohol-soluble polyamide resin can be used as the organic resin layer 180.

[0406] Furthermore, a photosensitive resin can be used as the organic resin layer 180. A photoresist can be used as the photosensitive resin. The photosensitive resin can be a positive type material or a negative type material.

[0407] The organic resin layer 180 may contain a material that absorbs visible light. For example, the organic resin layer 180 itself may be made of a material that absorbs visible light, or the organic resin layer 180 may contain a pigment that absorbs visible light. For example, the organic resin layer 180 may be made of 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.

[0408] In addition, a first electrode 101 (a first electrode 101R and a first electrode 101W) is provided on the organic resin layer 180, and an organic compound layer 103 is provided on the first electrode 101. Ends of the first electrode 101 and the organic compound layer 103 may be covered with an insulating layer 127.

[0409] Furthermore, the first electrode 101 formed on the organic resin layer 180 has a recess similar to the recess of the organic resin layer 180. Furthermore, the organic compound layer 103 formed on the first electrode 101 has a recess similar to the recess of the first electrode 101. Furthermore, the common layer 104 formed on the organic compound layer 103 has a recess similar to the recess of the organic compound layer 103. Furthermore, the common electrode 155 formed on the common layer 104 has a recess similar to the recess 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 one another.

[0410] In addition, 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 common electrode 155 is bonded to a substrate 352 via an adhesive layer 142.

[0411] Although light emitting device 130G and light emitting device 130B are not shown in FIG. 13, light emitting device 130G and light emitting device 130B are also provided.

[0412] [Display device 100E] The display device 100E shown in FIG. 14(A) is a modified example of the top-emission type display device 100B shown in FIG. 11(A), and differs from the display device 100B mainly in that it has colored layers 136R, 136G, and 136B.

[0413] In the display device 100E, the light-emitting device 130 has an area that overlaps one of the colored layer 136R, the colored layer 136G, and the colored layer 136B. The colored layer 136R, the colored layer 136G, and the colored layer 136B can be provided on the surface of the substrate 352 facing the substrate 351. An end of the colored layer 136R, an end of the colored layer 136G, and an end of the colored layer 136B can overlap the light-shielding layer 157.

[0414] 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 be configured such that the colored layers 136R, 136G, and 136B are provided between the protective layer 135 and the adhesive layer 142.

[0415] 11A, 14A, and the like show examples in which the top surface of the layer 128 has a flat portion, but there is no particular limitation on the shape of the layer 128. Modified examples of the layer 128 are shown in FIGS.

[0416] 14(B) and 14(D), the upper surface of layer 128 may have a shape with a recess in the center and its vicinity in cross section, i.e., a shape with a concave curve. In addition, common layer 154 may be provided so as to contact common electrode 155.

[0417] As shown in FIG. 14(C), the upper surface of the layer 128 can be configured to have a shape in which the center and its vicinity bulge in cross section, that is, a shape having a convex curve.

[0418] The upper surface of layer 128 may have one or both of a convex curved surface and a concave curved surface. The number of convex curved surfaces and concave curved surfaces that the upper surface of layer 128 has is not limited, and may be one or more.

[0419] Furthermore, the height of the upper surface of layer 128 and the height of the upper surface of conductive layer 224R may be the same or approximately the same, or may be different from each other. For example, the height of the upper surface of layer 128 may be lower or higher than the height of the upper surface of conductive layer 224R.

[0420] 14(B) can also be considered an example in which layer 128 is contained within a recess formed in conductive layer 224R. On the other hand, as shown in FIG. 14(D), layer 128 may be present outside the recess formed in conductive layer 224R, that is, the width of the upper surface of layer 128 may be wider than the recess.

[0421] [Display device 100F] The display device 100F shown in Fig. 15(A) is a modified example of the top-emission type display device 100B shown in Fig. 11, and has microlenses 182 on the colored layers 136R, 136G, and 136B. Note that in the drawing, the reference numerals of the same components as those in Fig. 11 may be omitted, and for details, the description in Fig. 11 may be referred to.

[0422] 15(B) shows a top view layout of a pixel 178 (pixels 178a and 178b) having subpixels 110 (subpixels 110R, 110G, and 110B), and FIG. 15(C) shows a top view of a microlens 182 in a region where the subpixels 110R, 110G, and 110B of the pixel 178 are formed. Note that the region where the common electrode 155 and the organic compound layer 103 are in contact has a width 110Gw in the light-emitting region of the subpixel 110G.

[0423] 13(A) has a planarization film 143 provided on a protective layer 135, and colored layers 136R, 136G, and 136B provided 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.

[0424] As shown in FIG. 15C, the microlens 182 may be provided for each sub-pixel in a region where the sub-pixel is formed.

[0425] 15(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 polygon such as a triangle, a quadrangle (including a rectangle and a square), a pentagon, or any other polygon with rounded corners, an ellipse, or a circle.

[0426] The microlenses 182 can be formed using the same material as the organic resin layer 180 .

[0427] This embodiment mode can be combined with other embodiment modes or examples as appropriate. In addition, in this specification, when multiple configuration examples are shown in one embodiment mode, the configuration examples can be combined as appropriate.

[0428] (Sixth embodiment) In this embodiment, an electronic device according to one embodiment of the present invention will be described.

[0429] The electronic devices of this embodiment include the light-emitting device of one embodiment of the present invention in their display portions. The light-emitting device of one embodiment of the present invention is highly reliable and can easily achieve high definition and high resolution. Therefore, the light-emitting device can be used in the display portions of various electronic devices.

[0430] Examples of electronic devices include electronic devices with relatively large screens such as television sets, desktop or notebook personal computers, computer monitors, digital signage, large game machines such as pachinko machines, as well as digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, personal digital assistants, and sound playback devices.

[0431] In particular, the light-emitting device of one embodiment of the present invention can have high resolution and can therefore be suitably used in electronic devices having a relatively small display portion. Examples of such electronic devices include wristwatch-type and bracelet-type information terminals (wearable devices), and head-mounted wearable devices such as VR devices (head-mounted displays), eyeglass-type AR devices, and MR devices.

[0432] The light-emitting device of one embodiment of the present invention preferably has an extremely high resolution such as HD (1280 × 720 pixels), FHD (1920 × 1080 pixels), WQHD (2560 × 1440 pixels), WQXGA (2560 × 1600 pixels), 4K (3840 × 2160 pixels), or 8K (7680 × 4320 pixels). A resolution of 4K, 8K, or higher is particularly preferable. Furthermore, the pixel density (resolution) of the light-emitting device of one embodiment of the present invention is preferably 100 ppi or higher, more preferably 300 ppi or higher, more preferably 500 ppi or higher, more preferably 1000 ppi or higher, more preferably 2000 ppi or higher, more preferably 3000 ppi or higher, more preferably 5000 ppi or higher, and even more preferably 7000 ppi or higher. By using a light-emitting device having either or both of high resolution and high definition, it is possible to further enhance the sense of realism and depth. Furthermore, the screen ratio (aspect ratio) of the light-emitting device according to one embodiment of the present invention is not particularly limited. For example, the light-emitting device can accommodate various screen ratios such as 1:1 (square), 4:3, 16:9, and 16:10.

[0433] The electronic device of this embodiment may have a sensor (including a function to measure force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared rays).

[0434] The electronic device of the present embodiment can have various functions, such as a function to display various information (still images, videos, text images, etc.) on a display unit, a touch panel function, a function to display a calendar, date, time, etc., a function to execute various software (programs), a wireless communication function, a function to read out programs or data recorded on a recording medium, etc.

[0435] 16(A) to 16(D), an example of a wearable device that can be worn on the head will be described. 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 have the function to display at least one of AR, VR, SR, and MR content, it is possible to enhance the user's sense of immersion.

[0436] The electronic device 700A shown in FIG. 16(A) and the electronic device 700B shown in FIG. 16(B) each have 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.

[0437] The light-emitting device of one embodiment of the present invention can be applied to the display panel 751. Therefore, the electronic device can be highly reliable.

[0438] Electronic device 700A and electronic device 700B can each project an image displayed on display panel 751 onto display area 756 of optical member 753. Because optical member 753 is translucent, the user can see the image displayed in the display area superimposed on a transmitted image visually recognized through optical member 753. Therefore, electronic device 700A and electronic device 700B are each electronic devices capable of AR display.

[0439] Electronic device 700A and electronic device 700B may be provided with a camera capable of capturing an image in front of them as an imaging unit. Furthermore, electronic device 700A and electronic device 700B may each be provided with an acceleration sensor such as a gyro sensor, thereby detecting the orientation of the user's head and displaying an image corresponding to that orientation in display area 756.

[0440] The communication unit has a wireless communication device, and can supply, for example, a video signal via the wireless communication device. Note that instead of or in addition to the wireless communication device, a connector to which a cable through which a video signal and a power supply potential can be connected may be provided.

[0441] Furthermore, the electronic device 700A and the electronic device 700B are provided with batteries, which can be charged wirelessly and / or by wire.

[0442] The housing 721 may be provided with a touch sensor module. The touch sensor module has a function of detecting a touch on the outer surface of the housing 721. The touch sensor module detects a tap operation, a slide operation, or the like by the user, and can execute various processes. For example, a tap operation can execute processes such as pausing or resuming a video, and a slide operation can execute processes such as fast-forwarding or fast-rewinding. Furthermore, providing a touch sensor module on each of the two housings 721 can broaden the range of operations.

[0443] Various touch sensors can be used as the touch sensor module. For example, various types of touch sensors can be used, such as a capacitance type, a resistive film type, an infrared type, an electromagnetic induction type, a surface acoustic wave type, or an optical type. In particular, it is preferable to use a capacitance type or an optical type sensor in the touch sensor module.

[0444] When an optical touch sensor is used, 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 or both of an inorganic semiconductor and an organic semiconductor.

[0445] The electronic device 800A shown in Figure 16(C) and the electronic device 800B shown in Figure 16(D) each have 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.

[0446] The light-emitting device of one embodiment of the present invention can be applied to the display portion 820. Therefore, the electronic device can be highly reliable.

[0447] Display unit 820 is provided inside housing 821 at a position that can be viewed through lens 832. Also, by displaying different images on the pair of display units 820, it is possible to perform a three-dimensional display using parallax.

[0448] Electronic device 800A and electronic device 800B can each be said to be electronic devices for VR. A user wearing electronic device 800A or electronic device 800B can view an image displayed on display unit 820 through lens 832.

[0449] It is preferable that electronic device 800A and electronic device 800B each have a mechanism that can adjust the left and right positions of lens 832 and display unit 820 so that they are optimally positioned according to the position of the user's eyes. It is also preferable that electronic device 800A and electronic device 800B each have a mechanism that can adjust the focus by changing the distance between lens 832 and display unit 820.

[0450] The user can wear the electronic device 800A or the electronic device 800B on the head by using the wearing unit 823. Note that, for example, in Fig. 16(C), the wearing unit 823 is shaped like the temples of glasses (also called joints or temples), but is not limited to this. The wearing unit 823 may be shaped like a helmet or a band, for example, as long as it can be worn by the user.

[0451] The imaging unit 825 has a function of acquiring external information. Data acquired by the imaging unit 825 can be output to the display unit 820. An image sensor can be used for the imaging unit 825. Furthermore, multiple cameras may be provided to support multiple angles of view, such as telephoto and wide angle.

[0452] Although an example having the imaging unit 825 has been shown here, a distance measuring sensor (hereinafter also referred to as a detection unit) capable of measuring the distance to an object may be provided. That is, the imaging unit 825 is one aspect of the detection unit. As the detection unit, for example, an image sensor or a range image sensor such as a LIDAR (Light Detection and Ranging) can be used. By using an image obtained by the camera and an image obtained by the range image sensor, more information can be obtained, enabling more accurate gesture operations.

[0453] 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 display unit 820, housing 821, and wearing unit 823. This allows a user to enjoy video and audio simply by wearing electronic device 800A, without the need for separate audio equipment such as headphones, earphones, or speakers.

[0454] The electronic device 800A and the electronic device 800B may each have an input terminal to which a cable can be connected for supplying a video signal from a video output device or the like and power for charging a battery provided in the electronic device.

[0455] The electronic device of one embodiment of the present invention may have a function of 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., audio data) from the electronic device through the wireless communication function. For example, the electronic device 700A shown in FIG. 16A has a function of transmitting information to the earphone 750 through the wireless communication function. Furthermore, for example, the electronic device 800A shown in FIG. 16C has a function of transmitting information to the earphone 750 through the wireless communication function.

[0456] 16(B) includes an earphone unit 727. For example, the earphone unit 727 and the control unit may be connected to each other by wire. Part of the wiring connecting the earphone unit 727 and the control unit may be disposed inside the housing 721 or the wearing unit 723.

[0457] 16(D) includes an earphone unit 827. For example, the earphone unit 827 and the control unit 824 can be configured to be connected to each other by wire. A portion of the wiring connecting the earphone unit 827 and the control unit 824 may be disposed inside the housing 821 or the wearing unit 823. The earphone unit 827 and the wearing unit 823 may also have a magnet. This allows the earphone unit 827 to be fixed to the wearing unit 823 by magnetic force, which is preferable as it makes storage easier.

[0458] The electronic device may have an audio output terminal to which earphones or headphones can be connected. The electronic device may also have one or both of an audio input terminal and an audio input mechanism. For example, a sound collection device such as a microphone can be used as the audio input mechanism. By having the audio input mechanism, the electronic device may be endowed with the functionality of a so-called headset.

[0459] As described above, the electronic devices of one embodiment of the present invention are preferably either glasses-type devices (such as the electronic devices 700A and 700B) or goggle-type devices (such as the electronic devices 800A and 800B).

[0460] Furthermore, the electronic device according to one embodiment of the present invention can transmit information to the earphone via a wired or wireless connection.

[0461] An electronic device 6500 shown in FIG. 17A is a portable information terminal that can be used as a smartphone.

[0462] The electronic device 6500 includes a housing 6501, a display portion 6502, a power button 6503, a button 6504, a speaker 6505, a microphone 6506, a camera 6507, and a light source 6508. The display portion 6502 has a touch panel function.

[0463] The light-emitting device of one embodiment of the present invention can be applied to the display portion 6502. Therefore, the electronic device can be highly reliable.

[0464] FIG. 17B is a schematic cross-sectional view including the end of the housing 6501 on the microphone 6506 side.

[0465] A light-transmitting protective member 6510 is provided on the display surface side of the housing 6501, and a display panel 6511, optical members 6512, a touch sensor panel 6513, a printed circuit board 6517, a battery 6518, etc. are arranged in the space surrounded by the housing 6501 and the protective member 6510.

[0466] A display panel 6511, an optical member 6512, and a touch sensor panel 6513 are fixed to the protective member 6510 by adhesive layers (not shown).

[0467] In an area outside the display unit 6502, a part of the display panel 6511 is folded back, and an FPC 6515 is connected to the folded back part. An IC 6516 is mounted on the FPC 6515. The FPC 6515 is connected to a terminal provided on a printed circuit board 6517.

[0468] The light-emitting device of one embodiment of the present invention can be applied to the display panel 6511. Therefore, an extremely lightweight electronic device can be realized. Furthermore, since the ...

Claims

1. a first electrode, a second electrode, a light-emitting layer, a first layer, and a second layer; the first electrode is formed on a substrate and is located between the second electrode and the substrate; the light-emitting layer is located between the first electrode and the second electrode; the first layer is located between the first electrode and the light-emitting layer; the second layer is located between the second electrode and the light-emitting layer; one of the first electrode and the second electrode is an anode, and the other is a cathode; the GSP_slope (mV / nm) of the layer of the light-emitting layer and the first layer located on the cathode side is larger than the GSP_slope (mV / nm) of the layer located on the anode side; A light-emitting device in which the GSP_slope (mV / nm) of the layer of the light-emitting layer and the second layer located on the anode side is larger than the GSP_slope (mV / nm) of the layer located on the cathode side (where GSP_slope (mV / nm) is a parameter expressed as ΔV / Δd when the change in film thickness Δd (nm) is the change in surface potential ΔV (mV)).

2. a first electrode, a second electrode, a light-emitting layer, a first layer, and a second layer; the first electrode is formed on a substrate and is located between the second electrode and the substrate; the light-emitting layer is located between the first electrode and the second electrode; the first layer is located between the first electrode and the light-emitting layer; the second layer is located between the second electrode and the light-emitting layer; the first electrode is an anode; the second electrode is a cathode; the GSP_slope (mV / nm) of the light-emitting layer is greater than the GSP_slope (mV / nm) of the first layer; A light-emitting device in which the GSP_slope (mV / nm) of the light-emitting layer is greater than the GSP_slope (mV / nm) of the second layer (where GSP_slope (mV / nm) is a parameter expressed as ΔV / Δd when the change in surface potential is ΔV (mV) relative to the change in film thickness Δd (nm).

3. a first electrode, a second electrode, a light-emitting layer, a first layer, and a second layer; the first electrode is formed on a substrate and is located between the second electrode and the substrate; the light-emitting layer is located between the first electrode and the second electrode; the first layer is located between the first electrode and the light-emitting layer; the second layer is located between the second electrode and the light-emitting layer; the first electrode is a cathode; the second electrode is an anode; the GSP_slope (mV / nm) of the first layer is greater than the GSP_slope (mV / nm) of the light-emitting layer; A light-emitting device in which the GSP_slope (mV / nm) of the second layer is greater than the GSP_slope (mV / nm) of the light-emitting layer (where GSP_slope (mV / nm) is a parameter expressed as ΔV / Δd when the change in surface potential is ΔV (mV) relative to the change in film thickness Δd (nm).

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

5. In claim 1, a third layer and a fourth layer; the third layer is located between the first layer and the first electrode; the fourth layer is located between the second layer and the second electrode; the GSP_slope (mV / nm) of the layer located on the cathode side of the first layer and the third layer is larger than the GSP_slope (mV / nm) of the layer located on the anode side; A light-emitting device, wherein the GSP_slope (mV / nm) of the layer of the second layer and the fourth layer that is located on the anode side is greater than the GSP_slope (mV / nm) of the layer that is located on the cathode side.

6. In claim 2, a third layer and a fourth layer; the third layer is located between the first layer and the first electrode; the fourth layer is located between the second layer and the second electrode; The GSP_slope (mV / nm) of the first layer is greater than the GSP_slope (mV / nm) of the third layer; A light-emitting device, wherein the GSP_slope (mV / nm) of the second layer is greater than the GSP_slope (mV / nm) of the fourth layer.

7. In claim 3, a third layer and a fourth layer; the third layer is located between the first layer and the first electrode; the fourth layer is located between the second layer and the second electrode; The GSP_slope (mV / nm) of the third layer is greater than the GSP_slope (mV / nm) of the first layer; A light emitting device, wherein the fourth layer has a GSP_slope (mV / nm) greater than the GSP_slope (mV / nm) of the second layer.

8. In any one of claims 5 to 7, A light-emitting device, wherein at a peak wavelength of an electroluminescence spectrum of the light-emitting device, at least one of the first layer, the second layer, the third layer, and the fourth layer has a refractive index of 1.75 or less.

9. a first electrode, a second electrode, a light-emitting layer, a first layer, and a second layer; the first electrode is formed on a substrate and is located between the second electrode and the substrate; the light-emitting layer is located between the first electrode and the second electrode; the first layer is located between the first electrode and the light-emitting layer; the second layer is located between the second electrode and the light-emitting layer; the first electrode is an anode; the second electrode is a cathode; the light-emitting layer comprises a first host material and a light-emitting material; the first layer comprises a first organic compound; the second layer comprises a second organic compound; a GSP_slope (mV / nm) of a vapor-deposited film of the first host material is larger than a GSP_slope (mV / nm) of a vapor-deposited film of the first organic compound; A light-emitting device in which the GSP_slope (mV / nm) of the vapor-deposited film of the first host material is larger than the GSP_slope (mV / nm) of the vapor-deposited film of the second organic compound (where GSP_slope (mV / nm) is a parameter expressed as ΔV / Δd when the change in film thickness Δd (nm) is the change in surface potential ΔV (mV)).

10. a first electrode, a second electrode, a light-emitting layer, a first layer, and a second layer; the first electrode is formed on a substrate and is located between the second electrode and the substrate; the light-emitting layer is located between the first electrode and the second electrode; the first layer is located between the first electrode and the light-emitting layer; the second layer is located between the second electrode and the light-emitting layer; the first electrode is a cathode; the second electrode is an anode; the light-emitting layer comprises a first host material and a light-emitting material; the first layer comprises a first organic compound; the second layer comprises a second organic compound; a GSP_slope (mV / nm) of a vapor-deposited film of the first organic compound is greater than a GSP_slope (mV / nm) of a vapor-deposited film of the first host material; A light-emitting device in which the GSP_slope (mV / nm) of the vapor-deposited film of the second organic compound is larger than the GSP_slope (mV / nm) of the vapor-deposited film of the first host material (where GSP_slope (mV / nm) is a parameter expressed as ΔV / Δd when the change in film thickness Δd (nm) is the change in surface potential ΔV (mV)).

11. a first electrode, a second electrode, a light-emitting layer, a first layer, and a second layer; the first electrode is formed on a substrate and is located between the second electrode and the substrate; the light-emitting layer is located between the first electrode and the second electrode; the first layer is located between the first electrode and the light-emitting layer; the second layer is located between the second electrode and the light-emitting layer; the first electrode is an anode; the second electrode is a cathode; the light-emitting layer comprises a first host material, a second host material, and a light-emitting substance; the first layer comprises a first organic compound; the second layer comprises a second organic compound; an average value of GSP_slope (mV / nm) of the vapor-deposited film of the first host material and GSP_slope (mV / nm) of the vapor-deposited film of the second host material is greater than the GSP_slope (mV / nm) of the vapor-deposited film of the first organic compound; A light-emitting device in which the average value of GSP_slope (mV / nm) of the vapor-deposited film of the first host material and the GSP_slope (mV / nm) of the vapor-deposited film of the second host material is greater than the GSP_slope (mV / nm) of the vapor-deposited film of the second organic compound (where GSP_slope (mV / nm) is a parameter expressed as ΔV / Δd when the change in film thickness Δd (nm) is the change in surface potential ΔV (mV)).

12. a first electrode, a second electrode, a light-emitting layer, a first layer, and a second layer; the first electrode is formed on a substrate and is located between the second electrode and the substrate; the light-emitting layer is located between the first electrode and the second electrode; the first layer is located between the first electrode and the light-emitting layer; the second layer is located between the second electrode and the light-emitting layer; the first electrode is a cathode; the second electrode is an anode; the light-emitting layer comprises a first host material, a second host material, and a light-emitting substance; the first layer comprises a first organic compound; the second layer comprises a second organic compound; a GSP_slope (mV / nm) of a vapor-deposited film of the first organic compound is greater than an average value of a GSP_slope (mV / nm) of a vapor-deposited film of the first host material and a GSP_slope (mV / nm) of a vapor-deposited film of the second host material; 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 average value of the GSP_slope (mV / nm) of the vapor-deposited film of the first host material and the GSP_slope (mV / nm) of the vapor-deposited film of the second host material (where GSP_slope (mV / nm) is a parameter expressed as ΔV / Δd when the change in film thickness Δd (nm) is the change in surface potential ΔV (mV)).

13. In any one of claims 9 to 12, A light-emitting device, wherein at least one of the refractive index of the film of the first organic compound and the refractive index of the film of the second organic compound is 1.75 or less at a peak wavelength of an electroluminescence spectrum of the light-emitting device.

14. In any one of claims 9 to 12, 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.

15. In claim 9 or claim 11, a third layer and a fourth layer; the third layer is located between the first layer and the first electrode; the fourth layer is located between the second layer and the second electrode; the third layer comprises a third organic compound; the fourth layer comprises a fourth organic compound; a GSP_slope (mV / nm) of the vapor-deposited film of the first organic compound is larger than a GSP_slope (mV / nm) of the vapor-deposited film of the third organic compound; A light-emitting device, wherein the GSP_slope (mV / nm) of the evaporated film of the second organic compound is greater than the GSP_slope (mV / nm) of the evaporated film of the fourth organic compound.

16. In claim 10 or claim 12, a third layer and a fourth layer; the third layer is located between the first layer and the first electrode; the fourth layer is located between the second layer and the second electrode; the third layer comprises a third organic compound; the fourth layer comprises a fourth organic compound; a GSP_slope (mV / nm) of the vapor-deposited film of the third organic compound is larger than a GSP_slope (mV / nm) of the vapor-deposited film of the first organic compound; A light-emitting device, wherein the GSP_slope (mV / nm) of the evaporated film of the fourth organic compound is greater than the GSP_slope (mV / nm) of the evaporated film of the second organic compound.

17. In claim 15, A light-emitting device, wherein at least one of the refractive index of the film of the first organic compound, the refractive index of the film of the second organic compound, the refractive index of the film of the third organic compound, and the refractive index of the film of the fourth organic compound is 1.75 or less at the peak wavelength of the electroluminescence spectrum of the light-emitting device.

18. In claim 15, At least one of the first organic compound, the second organic compound, 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.

19. In claim 15, the first organic compound and the third organic compound each independently have a π-electron-rich heteroaromatic ring or an aromatic amine skeleton; a HOMO level of the third organic compound higher than a HOMO level of the first organic compound;

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