Light-emitting device

Abstract

To provide a light-emitting device with excellent characteristics.SOLUTION: A light-emitting device includes a first electrode, a second electrode, a light-emitting layer, and a first layer. The light-emitting layer exists between the first electrode and the second electrode. The first layer exists between the light-emitting layer and the second electrode. The first layer includes at least one of metal and a metal compound, a first organic compound, and a second organic compound. The peak wavelength of the PL spectrum of a mixed film including the first organic compound and the second organic compound is longer than the peak wavelength of the PL spectrum of a single film of the first organic compound and the peak wavelength of the PL spectrum of a single film of the second organic compound at room temperature.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One embodiment of the present invention relates to a light-emitting device, a light-emitting apparatus, a display device, an electronic device, a lighting apparatus, and an electronic device. Note that one embodiment of the present invention is not limited to the above technical fields. The technical field of one embodiment of the invention disclosed in this specification etc. relates to an object, a method, or a manufacturing method. Alternatively, one embodiment of the present invention relates to a process, a machine, a manufacture, or a composition of matter. Therefore, more specific examples of the technical field of one embodiment 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, input devices (e.g., touch sensors), input / output devices (e.g., touch panels), driving methods thereof, and manufacturing methods thereof. [Background technology]

[0002] Display devices have been developed for a variety of applications in recent years. For example, applications of large display devices include home television devices (also called televisions or television receivers), digital signage (electronic billboards), and public information displays (PIDs), while applications of small display devices include smartphones and tablet terminals equipped with touch panels.

[0003] At the same time, there is also a demand for higher resolution display devices. Devices requiring high-resolution display devices include, for example, devices for virtual reality (VR), augmented reality (AR), substitutional reality (SR), and mixed reality (MR).

[0004] As display elements for use in display devices, the development of light-emitting devices (also referred to as light-emitting elements) has been actively promoted. Light-emitting devices (also referred to as EL devices or EL elements) utilizing the electroluminescence (hereinafter referred to as EL) phenomenon, particularly organic EL devices that mainly use organic compounds, are suitable for display devices because they have features such as being easily thin and lightweight, being capable of high-speed response to input signals, and being capable of being driven by a DC constant voltage power supply.

[0005] In order to obtain higher-definition display devices using organic EL devices, research has been conducted into patterning organic compound layers using photolithography instead of deposition methods using metal masks. By using photolithography, it is possible to obtain high-definition display devices with organic compound layers spaced apart by several micrometers (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 2018-521459 Summary of the Invention [Problem to be solved by the invention]

[0007] It has been known that exposure of the cathode and organic compound layers of organic EL devices to atmospheric components such as water and oxygen can affect their initial characteristics and reliability, and it has been common practice to fabricate organic EL devices in an inert gas atmosphere or a vacuum-like atmosphere. However, during the fabrication of organic EL devices, in the process of processing the organic compound layers using lithography methods such as photolithography as described above (hereinafter, this process may be referred to as the lithography process), the organic compound layers may be exposed to atmospheric components such as water and oxygen, as well as water and chemical solutions used in the photolithography process. Therefore, there is a need to develop organic EL devices with organic compound layers that are highly resistant to such environments.

[0008] An object of one embodiment of the present invention is to provide a novel light-emitting device. Alternatively, an object of one embodiment of the present invention is to provide a light-emitting device having good efficiency. Alternatively, an object of one embodiment of the present invention is to provide a light-emitting device having good reliability. Alternatively, an object of one embodiment of the present invention is to provide a light-emitting device having good efficiency and good reliability.

[0009] Another object of one embodiment of the present invention is to provide a novel light-emitting device manufactured by a lithography method.Another object of one embodiment of the present invention is to provide a light-emitting device manufactured by a lithography method and having good efficiency.Another object of one embodiment of the present invention is to provide a light-emitting device manufactured by a lithography method and having good reliability.Another object of one embodiment of the present invention is to provide a light-emitting device manufactured by a lithography method and having good emission efficiency and reliability.

[0010] Another object of one embodiment of the present invention is to provide a novel light-emitting device that can be used in a high-resolution display device.Another object of one embodiment of the present invention is to provide a light-emitting device that can be used in a high-resolution display device and has good efficiency.Another object of one embodiment of the present invention is to provide a light-emitting device that can be used in a high-resolution display device and has good reliability.Another object of one embodiment of the present invention is to provide a light-emitting device that can be used in a high-resolution display device and has good emission efficiency and reliability.

[0011] Note that the description of these problems does not preclude the existence of other problems. One embodiment of the present invention does not necessarily have to solve all of these problems. Problems other than these can be extracted from the description in the specification, drawings, and claims. [Means for solving the problem]

[0012] One embodiment of the present invention is a light-emitting device including a first electrode, a second electrode, a light-emitting layer, and a first layer, the light-emitting layer being located between the first electrode and the second electrode, the first layer being located between the light-emitting layer and the second electrode, the first layer including at least one of a metal and a metal compound, a first organic compound, and a second organic compound, and the peak wavelength of the PL spectrum of a mixed film including the first organic compound and the second organic compound is longer at room temperature than the peak wavelength of the PL spectrum of a single film of the first organic compound and the peak wavelength of the PL spectrum of a single film of the second organic compound.

[0013] Another embodiment of the present invention is a light-emitting device including a first electrode, a second electrode, a light-emitting layer, and a first layer, wherein the light-emitting layer is located between the first electrode and the second electrode, and the first layer is located between the light-emitting layer and the second electrode. The first layer includes at least one of a metal and a metal compound, a first organic compound, and a second organic compound, and the wavelength of a short-wavelength edge of a PL spectrum of a mixed film including the first organic compound and the second organic compound is longer at room temperature than the wavelengths of the short-wavelength edge of a PL spectrum of a single film of the first organic compound and the short-wavelength edge of a PL spectrum of a single film of the second organic compound.

[0014] 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 light-emitting layer, wherein the light-emitting layer is located between the first electrode and the second electrode, the first layer is located between the light-emitting layer and the second electrode, and the second light-emitting layer is located between the first layer and the second electrode, and the first layer includes at least one of a metal and a metal compound, a first organic compound, and a second organic compound, and the peak wavelength of the PL spectrum of the mixed film including the first organic compound and the second organic compound is longer at room temperature than the peak wavelength of the PL spectrum of a single film of the first organic compound and the peak wavelength of the PL spectrum of a single film of the second organic compound.

[0015] Another embodiment of the present invention is a light-emitting device including a first electrode, a second electrode, a first light-emitting layer, a first layer, and a second light-emitting layer, the first light-emitting layer and the second light-emitting layer being located between the first electrode and the second electrode, the first layer being located between the first light-emitting layer and the second light-emitting layer, the first layer including at least one of a metal and a metal compound, a first organic compound, and a second organic compound, and the wavelength of a short-wavelength edge of a PL spectrum of a mixed film including the first organic compound and the second organic compound is longer at room temperature than the wavelengths of the short-wavelength edge of a PL spectrum of a single film of the first organic compound and the short-wavelength edge of a PL spectrum of a single film of the second organic compound.

[0016] Another embodiment of the present invention is a light-emitting device including a first electrode, a second electrode, a light-emitting layer, and a first layer, wherein the light-emitting layer is located between the first electrode and the second electrode, and the first layer is located between the light-emitting layer and the second electrode. The first layer includes at least one of a metal and a metal compound, a first organic compound, and a second organic compound, and the peak wavelength of the PL spectrum of a mixed film including the at least one of the metal and the metal compound, the first organic compound, and the second organic compound is longer at room temperature than the peak wavelength of the PL spectrum of a single film of the first organic compound and the peak wavelength of the PL spectrum of a single film of the second organic compound.

[0017] Another embodiment of the present invention is a light-emitting device including a first electrode, a second electrode, a light-emitting layer, and a first layer, wherein the light-emitting layer is located between the first electrode and the second electrode, and the first layer is located between the light-emitting layer and the second electrode. The first layer includes at least one of a metal and a metal compound, a first organic compound, and a second organic compound, and the wavelength of a short-wavelength edge of a PL spectrum of a mixed film including the at least one of a metal and a metal compound, the first organic compound, and the second organic compound is longer at room temperature than the wavelengths of the short-wavelength edge of a PL spectrum of a single film of the first organic compound and the short-wavelength edge of a PL spectrum of a single film of the second organic compound.

[0018] Another embodiment of the present invention is a light-emitting device including a first electrode, a second electrode, a first light-emitting layer, a first layer, and a second light-emitting layer, the first light-emitting layer and the second light-emitting layer being located between the first electrode and the second electrode, the first layer being located between the first light-emitting layer and the second light-emitting layer, the first layer including at least one of a metal and a metal compound, a first organic compound, and a second organic compound, and the peak wavelength of the PL spectrum of a mixed film including the at least one of a metal and a metal compound, the first organic compound, and the second organic compound is longer at room temperature than the peak wavelength of the PL spectrum of a single film of the first organic compound and the peak wavelength of the PL spectrum of a single film of the second organic compound.

[0019] Another embodiment of the present invention is a light-emitting device including a first electrode, a second electrode, a first light-emitting layer, a first layer, and a second light-emitting layer, the first light-emitting layer and the second light-emitting layer being located between the first electrode and the second electrode, the first layer being located between the first light-emitting layer and the second light-emitting layer, and the first layer including at least one of a metal and a metal compound, a first organic compound, and a second organic compound, wherein the wavelength of a short-wavelength edge of a PL spectrum of a mixed film including the at least one of a metal and a metal compound, the first organic compound, and the second organic compound is longer at room temperature than the wavelengths of the short-wavelength edge of a PL spectrum of a single film of the first organic compound and the short-wavelength edge of a PL spectrum of a single film of the second organic compound.

[0020] Another embodiment of the present invention is a light-emitting device including a first electrode, a second electrode, a light-emitting layer, and a first layer, the light-emitting layer being located between the first electrode and the second electrode, the first layer being located between the light-emitting layer and the second electrode, the first layer including at least one of a metal and a metal compound, a first organic compound, and a second organic compound, and the wavelength of an absorption edge on the long-wavelength side of an absorption spectrum of a mixed film including the first organic compound and the second organic compound is longer than the wavelength of an absorption edge on the long-wavelength side of an absorption spectrum of a single film of the first organic compound and the wavelength of an absorption edge on the long-wavelength side of an absorption spectrum of a single film of the second organic compound at room temperature.

[0021] Another embodiment of the present invention is a light-emitting device including a first electrode, a second electrode, a first light-emitting layer, a first layer, and a second light-emitting layer, the first light-emitting layer and the second light-emitting layer being located between the first electrode and the second electrode, the first layer being located between the first light-emitting layer and the second light-emitting layer, the first layer including at least one of a metal and a metal compound, a first organic compound, and a second organic compound, and the wavelength of a long-wavelength absorption edge of an absorption spectrum of a mixed film including the first organic compound and the second organic compound is longer than the wavelengths of the long-wavelength absorption edge of an absorption spectrum of a single film of the first organic compound and the long-wavelength absorption edge of an absorption spectrum of a single film of the second organic compound at room temperature.

[0022] Another embodiment of the present invention is a light-emitting device including a first electrode, a second electrode, a light-emitting layer, and a first layer, wherein the light-emitting layer is located between the first electrode and the second electrode, and the first layer is located between the light-emitting layer and the second electrode. The first layer includes at least one of a metal and a metal compound, a first organic compound, and a second organic compound, and the wavelength of a long-wavelength absorption edge of an absorption spectrum of a mixed film including at least one of a metal and a metal compound, the first organic compound, and the second organic compound is longer than the wavelengths of the long-wavelength absorption edge of an absorption spectrum of a single film of the first organic compound and the long-wavelength absorption edge of an absorption spectrum of a single film of the second organic compound at room temperature.

[0023] Another embodiment of the present invention is a light-emitting device including a first electrode, a second electrode, a first light-emitting layer, a first layer, and a second light-emitting layer, the first light-emitting layer and the second light-emitting layer being located between the first electrode and the second electrode, the first layer being located between the first light-emitting layer and the second light-emitting layer, and the first layer including at least one of a metal and a metal compound, a first organic compound, and a second organic compound, wherein the wavelength of a long-wavelength absorption edge of an absorption spectrum of a mixed film including at least one of a metal and a metal compound, the first organic compound, and the second organic compound is longer than the wavelengths of the long-wavelength absorption edge of an absorption spectrum of a single film of the first organic compound and the long-wavelength absorption edge of an absorption spectrum of a single film of the second organic compound at room temperature.

[0024] Another embodiment of the present invention is a light-emitting device having any of the above structures, which further includes a second layer located between the first layer and the second electrode, a third organic compound and a fourth organic compound, the third organic compound being an organic compound having a π-electron-rich heteroaromatic ring or an aromatic amine, and the fourth organic compound having at least one of a halogen group and a cyano group. Among the light-emitting devices having any of the above structures, in a light-emitting device having a second light-emitting layer, the second layer is preferably located between the first layer and the second light-emitting layer.

[0025] In the light-emitting devices having the above structures, it is more preferable that the LUMO level of the first organic compound is higher than the LUMO level of the second organic compound.

[0026] In the light-emitting device having each of the above structures, it is more preferable that the HOMO level of the first organic compound is higher than the HOMO level of the second organic compound.

[0027] In the light-emitting devices having the above configurations, it is more preferable that the first organic compound and the second organic compound each have a heteroaromatic ring.

[0028] In the light-emitting devices having each of the above configurations, it is more preferable that the heteroaromatic ring of the first organic compound and the heteroaromatic ring of the second organic compound each independently include at least one of a pyridine ring, a pyrazine ring, a pyrimidine ring, a pyridazine ring, a triazine ring, an imidazole ring, a pyrazole ring, an oxazole ring, a thiazole ring, and a triazole ring.

[0029] In the light-emitting device having each of the above configurations, the first organic compound more preferably has an electron-donating group.

[0030] In the light-emitting devices having the above configurations, the electron-donating group is more preferably at least one of an alkyl group, an alkoxy group, an aryloxy group, an alkylamino group, an arylamino group, and a heterocyclic amino group.

[0031] In the light-emitting devices having the above configurations, the metal and metal compound preferably contain a metal belonging to Group 1, Group 3, Group 11 or Group 13 of the periodic table.

[0032] Another embodiment of the present invention is a light-emitting device having any of the above structures, which includes a third layer between the first layer and the second layer, and the thickness of the third layer is greater than 0 nm and less than or equal to 10 nm.

[0033] Another embodiment of the present invention is a light-emitting device having any of the above structures, in which the first layer and the second layer are provided in contact with each other.

[0034] In the light-emitting devices having each of the above configurations, it is more preferable that the light-emitting layer, the first light-emitting layer, or the second light-emitting layer contains a light-emitting substance, and that the wavelength of the absorption edge on the long-wavelength side of the absorption spectrum of the light-emitting substance is longer at room temperature than the wavelength of the emission edge on the short-wavelength side of the PL spectrum of the mixed film containing the first organic compound and the second organic compound. [Effects of the Invention]

[0035] According to one embodiment of the present invention, a novel light-emitting device can be provided. According to another embodiment of the present invention, a light-emitting device having high efficiency can be provided. According to another embodiment of the present invention, a light-emitting device having high reliability can be provided. According to another embodiment of the present invention, a light-emitting device having high efficiency and high reliability can be provided.

[0036] According to one embodiment of the present invention, a novel light-emitting device manufactured by a lithography method can be provided. According to another embodiment of the present invention, a light-emitting device manufactured by a lithography method and having high efficiency can be provided. According to one embodiment of the present invention, a light-emitting device manufactured by a lithography method and having high reliability can be provided. According to one embodiment of the present invention, a light-emitting device manufactured by a lithography method and having high emission efficiency and reliability can be provided.

[0037] Alternatively, one embodiment of the present invention can provide a novel light-emitting device that can be used in a high-resolution display device. Alternatively, one embodiment of the present invention can provide a light-emitting device that can be used in a high-resolution display device and has good efficiency. Alternatively, one embodiment of the present invention can provide a light-emitting device that can be used in a high-resolution display device and has good reliability. Alternatively, one embodiment of the present invention can provide a light-emitting device that can be used in a high-resolution display device and has good emission efficiency and reliability.

[0038] Note that the description of these effects does not preclude the existence of other effects. One embodiment of the present invention does not necessarily have all of these effects. Effects other than these can be extracted from the description in the specification, drawings, and claims. [Brief explanation of the drawings]

[0039] [Figure 1] 1(A) and 1(B) are diagrams illustrating the configuration of a light-emitting device according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating the configuration of the light-emitting device according to the embodiment. [Figure 3] 3(A) to 3(C) show the analysis results of the spin density distribution in the ground state of the composite material. [Figure 4] Figure 4 shows the analysis results of the spin density distribution in the ground state of the composite material. [Figure 5] 5(A) and 5(B) show the results of electrostatic potential map analysis of an organic compound in the ground state. [Figure 6] 6(A) to 6(C) show the analysis results of the electrostatic potential map of the composite material in the ground state. [Figure 7] Figure 7 shows the analysis results of the electrostatic potential map in the ground state of the composite material. [Figure 8] 8A to 8D are diagrams illustrating the configuration of a light-emitting device according to an embodiment. [Figure 9] 9(A) and 9(B) are a top view and a cross-sectional view of the light-emitting device. [Figure 10] 10A to 10E are cross-sectional views showing an example of a method for manufacturing a light-emitting device. [Figure 11] 11A and 11B are cross-sectional views showing an example of a method for manufacturing a light-emitting device. [Figure 12] 12A to 12D are cross-sectional views showing an example of a method for manufacturing a light-emitting device. [Figure 13] 13A to 13C are cross-sectional views showing an example of a method for manufacturing a light-emitting device. [Figure 14] 14A to 14C are cross-sectional views showing an example of a method for manufacturing a light-emitting device. [Figure 15] 15A to 15C are cross-sectional views showing an example of a method for manufacturing a light-emitting device. [Figure 16] 16A to 16G are top views showing examples of pixel configurations. [Figure 17] 17A to 17I are top views showing examples of pixel configurations. [Figure 18] 18(A) and 18(B) are perspective views showing configuration examples of a display module. [Figure 19] 19(A) and 19(B) are cross-sectional views showing examples of the configuration of a light-emitting device. [Figure 20] FIG. 20 is a perspective view showing an example of the configuration of a light emitting device. [Figure 21] Fig. 21A is a cross-sectional view showing a structural example of a light-emitting device, Fig. 21B and Fig. 21C are cross-sectional views showing structural examples of a transistor. [Figure 22] FIG. 22 is a cross-sectional view showing an example of the configuration of a light emitting device. [Figure 23] 23A to 23C are cross-sectional views and top views showing structural examples of a light-emitting device. [Figure 24] 24A to 24D are cross-sectional views showing examples of the configuration of a light-emitting device. [Figure 25] 25A to 25C are cross-sectional views and top views showing structural examples of a light-emitting device. [Figure 26] 26A to 26D are diagrams showing examples of electronic devices. [Figure 27] 27(A) to 27(F) are diagrams showing examples of electronic devices. [Figure 28] 28A to 28G are diagrams showing examples of electronic devices. [Figure 29] FIG. 29 shows the PL spectra of a single film of Hid2Phen, a single film of 6,6′(P-Bqn)2BPy, a mixed film 1, and a mixed film 2. [Figure 30] FIG. 30 is a diagram showing an example of determining the light-emitting edge from the PL spectrum. [Figure 31] FIG. 31 shows the PL spectra of a single film of Pyrrd-Phen, a single film of 6,6′(P-Bqn)2BPy, and the mixed film 3. [Figure 32] FIG. 32 shows the PL spectra of a single film of mPPhen2P, a single film of Pyrrd-Phen, and the mixed film 4. [Figure 33] FIG. 33 shows the PL spectra of a single film of DBimiBphen, a single film of Hid2Phen, and the mixed film 5. [Figure 34] 34(A) and 34(B) are diagrams showing the absorption spectra of a single film of Hid2Phen, a single film of 6,6′(P-Bqn)2BPy, and the mixed film 2. [Figure 35]FIG. 35 shows the absorption spectra of a single film of mPPhen2P, a single film of Pyrrd-Phen, and a mixed film 6. [Figure 36] FIG. 36 is a graph showing the luminance-current density characteristics of the light-emitting device 1a and the light-emitting device 2a. [Figure 37] FIG. 37 is a diagram showing the luminance-voltage characteristics of the light-emitting device 1a and the light-emitting device 2a. [Figure 38] FIG. 38 is a graph showing the current efficiency-luminance characteristics of the light-emitting device 1a and the light-emitting device 2a. [Figure 39] FIG. 39 is a graph showing the current density-voltage characteristics of the light-emitting device 1a and the light-emitting device 2a. [Figure 40] FIG. 40 shows the electroluminescence spectra of light-emitting device 1a and light-emitting device 2a. [Figure 41] FIG. 41 is a graph showing the luminance-current density characteristics of the light-emitting device 1b and the light-emitting device 2b. [Figure 42] FIG. 42 is a diagram showing the luminance-voltage characteristics of the light-emitting device 1b and the light-emitting device 2b. [Figure 43] FIG. 43 is a graph showing the current efficiency-luminance characteristics of the light-emitting device 1b and the light-emitting device 2b. [Figure 44] FIG. 44 is a graph showing the current density-voltage characteristics of the light-emitting device 1b and the light-emitting device 2b. [Figure 45] FIG. 45 shows the electroluminescence spectra of light-emitting device 1b and light-emitting device 2b. [Figure 46] FIG. 46 is a graph showing the luminance-current density characteristics of the light-emitting device 3a and the light-emitting device 4a. [Figure 47] FIG. 47 is a diagram showing the luminance-voltage characteristics of the light-emitting device 3a and the light-emitting device 4a. [Figure 48] FIG. 48 is a graph showing the current efficiency-luminance characteristics of the light-emitting device 3a and the light-emitting device 4a. [Figure 49] FIG. 49 is a diagram showing the current density-voltage characteristics of the light-emitting device 3a and the light-emitting device 4a. [Figure 50]FIG. 50 is a diagram showing the blue index-luminance characteristics of the light-emitting device 3a and the light-emitting device 4a. [Figure 51] FIG. 51 shows the electroluminescence spectra of light-emitting device 3a and light-emitting device 4a. [Figure 52] FIG. 52 is a graph showing the luminance-current density characteristics of the light-emitting device 3b and the light-emitting device 4b. [Figure 53] FIG. 53 is a diagram showing the luminance-voltage characteristics of the light-emitting device 3b and the light-emitting device 4b. [Figure 54] FIG. 54 is a graph showing the current efficiency-luminance characteristics of the light-emitting device 3b and the light-emitting device 4b. [Figure 55] FIG. 55 is a graph showing the current density-voltage characteristics of the light-emitting device 3b and the light-emitting device 4b. [Figure 56] FIG. 56 is a diagram showing the blue index-luminance characteristics of the light-emitting device 3b and the light-emitting device 4b. [Figure 57] FIG. 57 shows the electroluminescence spectra of light-emitting device 3b and light-emitting device 4b. [Figure 58] FIG. 58 is a diagram showing the luminance-current density characteristics of the light-emitting device 5a, the light-emitting device 5b, the light-emitting device 6a, and the light-emitting device 6b. [Figure 59] FIG. 59 is a diagram showing the luminance-voltage characteristics of the light-emitting device 5a, the light-emitting device 5b, the light-emitting device 6a, and the light-emitting device 6b. [Figure 60] FIG. 60 is a graph showing the current efficiency-current density characteristics of the light-emitting device 5a, the light-emitting device 5b, the light-emitting device 6a, and the light-emitting device 6b. [Figure 61] FIG. 61 is a diagram showing the current density-voltage characteristics of the light emitting device 5a, the light emitting device 5b, the light emitting device 6a, and the light emitting device 6b. [Figure 62] FIG. 62 shows the electroluminescence spectra of light-emitting device 5a, light-emitting device 5b, light-emitting device 6a, and light-emitting device 6b. [Figure 63]FIG. 63 is a diagram showing the change in luminance with respect to the driving time of the light emitting devices 5a, 5b, 6a, and 6b. [Figure 64] FIG. 64 is a diagram showing the luminance-current density characteristics of the light-emitting device 7a and the light-emitting device 7b. [Figure 65] FIG. 65 is a diagram showing the luminance-voltage characteristics of the light-emitting device 7a and the light-emitting device 7b. [Figure 66] FIG. 66 is a graph showing the current efficiency-current density characteristics of the light-emitting device 7a and the light-emitting device 7b. [Figure 67] FIG. 67 is a diagram showing the current density-voltage characteristics of the light-emitting device 7a and the light-emitting device 7b. [Figure 68] FIG. 68 shows the electroluminescence spectra of light-emitting device 7a and light-emitting device 7b. [Figure 69] FIG. 69 is a diagram showing the change in luminance of the light-emitting device 7a and the light-emitting device 7b with respect to the driving time. DETAILED DESCRIPTION OF THE INVENTION

[0040] The embodiments will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it will be readily understood by those skilled in the art that various changes can be made in form and detail without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the description of the embodiments shown below.

[0041] In the configuration of the invention described below, the same parts or parts having similar functions are denoted by the same reference numerals in different drawings, and repeated explanations thereof will be omitted. In addition, when referring to similar functions, the same hatch pattern may be used and no particular reference numeral may be assigned.

[0042] Furthermore, for ease of understanding, the position, size, range, etc. of each component shown in the drawings may not represent the actual position, size, range, etc. Therefore, the disclosed invention is not necessarily limited to the position, size, range, etc. disclosed in the drawings.

[0043] The terms "film" and "layer" can be interchangeable depending on the circumstances. For example, the term "conductive layer" can be changed to the term "conductive film." Or, for example, the term "insulating film" can be changed to the term "insulating layer."

[0044] In this specification, ordinal numbers such as "first" and "second" are used for convenience and do not limit the number of components or the order of the components (e.g., the order of processes or the order of stacking). In addition, the ordinal numbers assigned to components in one part of this specification may not match the ordinal numbers assigned to the same components in other parts of this specification or in the claims. In addition, in some cases, ordinal numbers are not assigned in this specification or the claims.

[0045] In this specification, etc., a device fabricated using a metal mask or an FMM (fine metal mask, high-resolution metal mask) may be referred to as a device with an MM (metal mask) structure. In addition, in this specification, etc., a device fabricated without using a metal mask or an FMM may be referred to as a device with an MML (metal maskless) structure.

[0046] In this specification and the like, a light-emitting device (also referred to as a light-emitting element) has an EL layer (also referred to as an organic compound layer) between a pair of electrodes. The EL layer has at least a light-emitting layer.

[0047] In this specification, a tapered shape refers to a shape in which at least a portion of the side surface of the structure is inclined relative to the substrate surface. For example, it is preferable to have a region in which the angle (also called the taper angle) between the inclined side surface and the substrate surface is less than 90 degrees. The side surface of the structure and the substrate surface do not necessarily need to be completely flat, and may be approximately planar with a slight curvature or approximately planar with a slight unevenness.

[0048] (Embodiment 1) In this embodiment, a light-emitting device of one embodiment of the present invention will be described with reference to FIGS.

[0049] 1A shows a schematic diagram of two adjacent light-emitting devices, a light-emitting device 130a and a light-emitting device 130b, formed on the same insulating surface and included in a light-emitting device to describe a light-emitting device according to one embodiment of the present invention. The light-emitting device 130a and the light-emitting device 130b are light-emitting devices in which parts of the organic compound layers are processed by lithography. The light-emitting device 130a and the light-emitting device 130b are tandem light-emitting devices each having a structure in which multiple light-emitting units are stacked with an intermediate layer sandwiched therebetween.

[0050] The light-emitting device 130a is located on an insulating layer 175 and includes a first electrode 101a including an anode, a second electrode 102 including a cathode, and an organic compound layer 103a. The organic compound layer 103a is located between the first electrode 101a and the second electrode 102. The organic compound layer 103a includes a first light-emitting unit 501a and a second light-emitting unit 502a stacked with an intermediate layer 160a sandwiched therebetween. The first light-emitting unit 501a includes a first light-emitting layer 113a_1. The intermediate layer 160a includes a first layer 161a and a second layer 162a. The second light-emitting unit 502a includes a second light-emitting layer 113a_2 and an electron injection layer 115. It can also be said that the intermediate layer 160a is located between the first light-emitting layer 113a_1 and the second light-emitting layer 113a_2.

[0051] In the light-emitting device 130a, each layer of the organic compound layer 103a except for the electron injection layer 115 is processed by lithography. Therefore, each layer of the organic compound layer 103a except for the electron injection layer 115 is independent of the adjacent light-emitting device, the light-emitting device 130b. Furthermore, the edges (outlines) of each layer of the organic compound layer 103a except for the electron injection layer 115 are aligned or approximately aligned in the vertical direction with respect to the substrate. That is, the first light-emitting layer 113a_1, the intermediate layer 160a (the first layer 161a and the second layer 162a), and the second light-emitting layer 113a_2 are independent of the first light-emitting layer 113b_1, the intermediate layer 160b (the first layer 161b and the second layer 162b), and the second light-emitting layer 113b_2. The edges (outlines) of the first light-emitting layer 113a_1, the intermediate layer 160a (the first layer 161a and the second layer 162a), and the second light-emitting layer 113a_2 are aligned or approximately aligned in the direction perpendicular to the substrate.

[0052] The light-emitting device 130b is located on the insulating layer 175 and includes a first electrode 101b including an anode, a second electrode 102 including a cathode, and an organic compound layer 103b. The organic compound layer 103b is located between the first electrode 101b and the second electrode 102. The organic compound layer 103b includes a first light-emitting unit 501b and a second light-emitting unit 502b stacked with an intermediate layer 160b sandwiched therebetween. The first light-emitting unit 501b includes a first light-emitting layer 113b_1. The intermediate layer 160b includes a first layer 161b and a second layer 162b. The second light-emitting unit 502b includes a second light-emitting layer 113b_2 and an electron injection layer 115. It can also be said that the intermediate layer 160b is located between the first light-emitting layer 113b_1 and the second light-emitting layer 113b_2.

[0053] In the light-emitting device 130b, each layer of the organic compound layer 103b except for the electron injection layer 115 is processed by lithography. Therefore, each layer of the organic compound layer 103b except for the electron injection layer 115 is independent (also referred to as being separated) from the adjacent light-emitting device, the light-emitting device 130a. Furthermore, the edges (outlines) of each layer of the organic compound layer 103b except for the electron injection layer 115 are aligned or approximately aligned in the vertical direction relative to the substrate. That is, the first light-emitting layer 113b_1, the intermediate layer 160b (the first layer 161b and the second layer 162b), and the second light-emitting layer 113b_2 are independent from the first light-emitting layer 113a_1, the intermediate layer 160a (the first layer 161a and the second layer 162a), and the second light-emitting layer 113a_2. The edges (outlines) of the first light-emitting layer 113b_1, the intermediate layer 160b (the first layer 161b and the second layer 162b), and the second light-emitting layer 113b_2 are aligned or approximately aligned in the direction perpendicular to the substrate.

[0054] The electron injection layer 115 and the second electrode 102 are preferably formed after processing, by lithography, each layer of the organic compound layer 103a other than the electron injection layer 115 and each layer of the organic compound layer 103b other than the electron injection layer 115. In other words, the electron injection layer 115 and the second electrode 102 are preferably a continuous layer shared by the light-emitting device 130a and the light-emitting device 130b.

[0055] The use of a material having donor properties, such as an alkali metal or alkaline earth metal, or a compound thereof, for the electron injection layer 115 is preferable because it allows for a lower voltage operation of the light-emitting device. However, when an organic compound layer having an electron injection layer containing such a donor substance on its outermost surface is processed using a lithography method, the influence of oxygen or water in the atmosphere, or chemical solutions or water used during the process, may cause a significant increase in the driving voltage or a significant decrease in the current efficiency of the light-emitting device.

[0056] On the other hand, when a light-emitting device is fabricated by a method in which the organic compound layers other than the electron injection layer 115 are processed using lithography, as in the light-emitting devices 130a and 130b, and then the electron injection layer 115 and the second electrode 102 are formed, the electron injection layer 115 is less susceptible to the effects of oxygen or water in the atmosphere and chemical solutions or water used in the process, and therefore a light-emitting device with good characteristics can be obtained.

[0057] By processing the organic compound layers using lithography, the distance between the organic compound layers can be narrowed compared to mask deposition. Specifically, the distance d between each layer other than the electron injection layer 115 of the organic compound layer 103a and each layer other than the electron injection layer 115 of the organic compound layer 103b can be narrowed to less than 10 μm, 8 μm or less, 5 μm or less, 3 μm or less, 2 μm or less, 1.5 μm or less, 1 μm or less, or 0.5 μm or less. Furthermore, by using an exposure tool for LSIs, for example, in a process on a Si wafer, the distance d can be narrowed to, for example, 500 nm or less, 200 nm or less, 100 nm or less, or even 50 nm or less.

[0058] Preferably, an insulating layer is provided in the gap between each layer of the organic compound layer 103a other than the electron injection layer 115 and each layer of the organic compound layer 103b other than the electron injection layer 115, thereby separating each layer of the organic compound layer 103a other than the electron injection layer 115 from each layer of the organic compound layer 103b other than the electron injection layer 115. In this case, there is a region where the insulating layer is in contact with the electron injection layer 115 or the second electrode 102.

[0059] In the light-emitting device 130a, the first light-emitting unit 501a preferably includes a hole-injection layer 111a, a first hole-transport layer 112a_1, and a first electron-transport layer 114a_1 in addition to the first light-emitting layer 113a_1. The second light-emitting unit 502a preferably includes a second hole-transport layer 112a_2 and a second electron-transport layer 114a_2 in addition to the second light-emitting layer 113a_2 and the electron-injection layer 115. The intermediate layer 160a may include a third layer 163a between the first layer 161a and the second layer 162a. In addition, when the anode side surface of the light-emitting unit is in contact with the intermediate layer 160a, as in the second light-emitting unit 502a, the second layer 162a of the intermediate layer 160a located on the cathode side can also serve as a hole injection layer for the second light-emitting unit 502a. Therefore, although it may not be necessary to provide a hole injection layer for the light-emitting unit, it may be provided.

[0060] In the light-emitting device 130b, the first light-emitting unit 501b preferably includes a hole-injection layer 111b, a first hole-transport layer 112b_1, and a first electron-transport layer 114b_1 in addition to the first light-emitting layer 113b_1. The second light-emitting unit 502b preferably includes a second hole-transport layer 112b_2 and a second electron-transport layer 114b_2 in addition to the second light-emitting layer 113b_2 and the electron-injection layer 115. The intermediate layer 160b may include a third layer 163b between the first layer 161b and the second layer 162b. In addition, when the anode side surface of the light-emitting unit is in contact with the intermediate layer 160b, as in the second light-emitting unit 502b, the second layer 162b of the intermediate layer 160b located on the cathode side can also serve as a hole injection layer for the second light-emitting unit 502b. Therefore, although it may not be necessary to provide a hole injection layer for the light-emitting unit, it may be provided.

[0061] 1A, the uppermost layer of each layer of the organic compound layer 103a other than the electron injection layer 115 is preferably the second electron transport layer 114a_2. Similarly, the uppermost layer of each layer of the organic compound layer 103b other than the electron injection layer 115 is preferably the second electron transport layer 114b_2. When an organic compound layer having the second electron transport layer 114a_2 and the second electron transport layer 114b_2 on its outermost surface is processed by lithography, the second light-emitting layer 113a_2 and the second light-emitting layer 113b_2 are less susceptible to the effects of oxygen or water in the atmosphere and chemicals or water used in the process, compared to processing an organic compound layer having the second light-emitting layer 113a_2 and the second light-emitting layer 113b_2 on its outermost surface, since the second electron transport layer 114a_2 and the second electron transport layer 114b_2 are provided as upper layers. That is, it is preferable to process at least the second light-emitting layer 113a_2 and the second light-emitting layer 113b_2 of each organic compound layer by lithography, and it is more preferable to process the second electron-transporting layer 114a_2 and the second electron-transporting layer 114b_2 as the uppermost layers by lithography, which can further easily avoid deterioration of the characteristics of the light-emitting device due to fabrication by lithography.

[0062] Although FIG. 1A illustrates an example in which each organic compound layer includes two light-emitting units, one embodiment of the present invention is not limited thereto. Each organic compound layer may include three or more light-emitting units. By stacking multiple light-emitting units between a pair of electrodes with an intermediate layer sandwiched therebetween, a highly reliable light-emitting device can be realized, which can emit high-luminance light while maintaining low current density. Furthermore, a light-emitting device with low power consumption can be realized. Although not illustrated in FIG. 1A, each light-emitting unit may include a hole-injection layer, a hole-transport layer, an electron-blocking layer, a hole-blocking layer, an electron-transporting layer, an electron-injection layer, or the like in addition to the above-described structure. Each layer may be a stack of two or more layers.

[0063] In this specification, the configuration of one of the light-emitting devices 130a and 130b may be exemplified, but the same configuration may also be used for the other.

[0064] The intermediate layer 160a sandwiched between the first light-emitting unit 501a and the second light-emitting unit 502a may inject electrons into one light-emitting unit and holes into the other light-emitting unit when, for example, a voltage is applied between the first electrode 101a and the second electrode 102. For example, in FIG. 1A, when a voltage is applied so that the potential of the second electrode 102 is higher than the potential of the first electrode 101a, the intermediate layer 160a injects electrons into the first light-emitting unit 501a and holes into the second light-emitting unit 502a.

[0065] In the light-emitting device 130a illustrated in FIG. 1A, when a voltage is applied between a pair of electrodes (a first electrode 101a and a second electrode 102), electrons are injected from the cathode into the electron injection layer 115, and holes are injected from the anode into the hole injection layer 111a, thereby causing a current to flow. Furthermore, electrons are injected from the first layer 161a located on the anode side of the intermediate layer 160a into the first electron transport layer 114a_1 in the first light-emitting unit 501a, and holes are injected from the second layer 162a located on the cathode side of the intermediate layer 160a into the second hole transport layer 112a_2 in the second light-emitting unit 502a. The injected carriers (electrons and holes) are then recombined to form excitons. In the first light-emitting layer 113a_1 and the second light-emitting layer 113a_2 containing light-emitting materials, when carriers (electrons and holes) recombine to form excitons, the light-emitting materials contained in the first light-emitting layer 113a_1 and the second light-emitting layer 113a_2 enter an excited state, and light is emitted from the light-emitting materials.

[0066] 1A, the first layer 161a of the intermediate layer 160a located on the anode side is preferably provided adjacent to the first electron-transporting layer 114a_1 and between the first electron-transporting layer 114a_1 and the second light-emitting unit 502a. With this configuration, electrons can be efficiently injected into the first light-emitting unit 501a.

[0067] To reduce the driving voltage of a light-emitting device and achieve efficient light emission, it is preferable to reduce the electron injection barrier from the intermediate layer to the first electron transport layer, thereby enabling electrons generated in the intermediate layer to be smoothly injected and transported to the first electron transport layer. To achieve this, alkali metals or alkaline earth metals and their compounds with low work functions are typically used in the first layer of the intermediate layer. However, these metals and compounds are susceptible to degradation by oxygen or water in the atmosphere, as well as water or chemicals used in lithography processes, resulting in a significant increase in the driving voltage or a significant decrease in the current efficiency of the light-emitting device. Alternatively, a metal that is stable to oxygen and water in the atmosphere and resistant to water and chemicals could be used in the first layer of the intermediate layer. However, such metals are stable and have poor electron injection properties, which can create an electron injection barrier between the intermediate layer 160a and the first electron transport layer 114a_1, resulting in problems such as an increase in the driving voltage of the light-emitting device and a decrease in luminous efficiency.

[0068] 2 is a schematic diagram showing modified examples of the light-emitting device 130a and the light-emitting device 130b shown in FIG. 1A. The light-emitting device 130a and the light-emitting device 130b are light-emitting devices in which the entire organic compound layer including the electron injection layer is processed using lithography.

[0069] The organic compound layer 103a of the light-emitting device 130a shown in Fig. 2 is independent of the adjacent light-emitting device 130b, and has an electron injection layer 115a having edges (outlines) that are aligned or approximately aligned with the other layers in the vertical direction relative to the substrate. The organic compound layer 103b of the light-emitting device 130b shown in Fig. 2 is independent of the adjacent light-emitting device 130a, and has an electron injection layer 115b having edges (outlines) that are aligned or approximately aligned with the other layers in the vertical direction relative to the substrate. The light-emitting devices 130a, 130b, and their surrounding structures shown in Fig. 2 are similar to those shown in Fig. 1(A), and therefore will not be described here.

[0070] As shown in Figure 2, in a light-emitting device in which the entire organic compound layer including the electron injection layer is processed using a lithography method, it is preferable to use a material that is resistant to water and chemical solutions used during the process for the electron injection layer and intermediate layer.

[0071] Therefore, in one aspect of the present invention, a light-emitting device is provided in which the configuration of layer 200 described below is applied to either the first layer (161a, 161b) of the intermediate layer (160a, 160b) or the electron injection layer (115, 115a, 115b).

[0072] [Layer 200] As shown in FIG. 1B, the layer 200 includes a metal or metal compound 161_M, a first organic compound 161_1, and a second organic compound 161_2. In the composite material, the metal or metal compound 161_M and the first organic compound 161_1 interact with each other to form a donor level (a SOMO (Singly Occupied Molecular Orbital) level or a HOMO (Highest Occupied Molecular Orbital) level), and can function as an electron donor for the second organic compound 161_2. With this structure, a layer having good electron injection properties and resistance to oxygen and water in the atmosphere, as well as water and chemicals used in a lithography process, can be formed.

[0073] Furthermore, it is preferable to apply a mixed layer containing a metal or metal compound 161_M, a first organic compound 161_1, and a second organic compound 161_2 to the layer 200. By forming the layer 200 as a mixed layer of a metal or metal compound 161_M, a first organic compound 161_1, and a second organic compound 161_2, these substances are more likely to interact with each other, allowing the first organic compound 161_1 and the metal or metal compound 161_M to function as electron donors for the second organic compound 161_2. Furthermore, the layer 200 having such a structure can be made less likely to crystallize than a layer having a stacked structure. Therefore, when a portion of the organic compound layer including such a layer is processed by lithography, it can be made a layer that is less likely to crystallize even when affected by oxygen or water in the atmosphere or chemical solutions or water during processing. Furthermore, it is possible to prevent an increase in the driving voltage or a decrease in the current efficiency of the light-emitting device due to crystallization of the intermediate layer or the electron injection layer. Therefore, by forming the organic compound layer as a mixed layer rather than a laminated structure, the organic compound layer can be suitably used as an intermediate layer in a light-emitting device in which a part of the organic compound layer is processed by lithography.

[0074] In the layer 200, the metal or metal compound 161_M and the first organic compound 161_1 interact to form a donor level, which further functions as an electron donor for the second organic compound 161_2. Therefore, by using the layer 200 as the first layer (161a, 161b) of the intermediate layers (160a, 160b), electrons generated in the first layer can be easily injected into the first light-emitting unit. Alternatively, electrons generated in the second layer (second layer 162a and second layer 162b) located on the cathode side of the intermediate layer can be easily injected into the first light-emitting unit. Therefore, since electrons can be easily injected into the first light-emitting unit, the driving voltage of the light-emitting device can be reduced and the light-emitting efficiency can be improved.

[0075] Furthermore, by using the layer 200 as the electron injection layer (115, 115a, 115b), the electron injection barrier from the second electrode 102 to the organic compound layers (103a, 103b) can be reduced, and the electrons injected from the second electrode 102 can be smoothly injected and transported to the light-emitting layers (113a, 113b), thereby reducing the driving voltage and providing a light-emitting device with high light-emitting efficiency.

[0076] The metal or metal compound 161_M can be a metal element with a small work function, such as an alkali metal or alkaline earth metal, a transition metal (a metal element of Groups 3 to 11), or a metal element of Groups 12 to 14, or a compound of these metals.

[0077] Metals and metal compounds with low work functions, such as alkali metals and alkaline earth metals, are highly reactive with oxygen and water. Therefore, when used in light-emitting devices processed by lithography, they can cause reduced luminous efficiency, increased driving voltage, reduced driving lifetime, and the formation of non-light-emitting regions at the edges of the light-emitting portion, leading to reduced characteristics and reliability of the light-emitting device. However, in one embodiment of the present invention, even when alkali metals and alkaline earth metals and their compounds are used, they are stabilized by interacting with the first organic compound 161_1 and the second organic compound 161_2, allowing the formation of an intermediate layer that is resistant to oxygen and water in the atmosphere, as well as water and chemicals used in the lithography process. By using alkali metals and alkaline earth metals and their compounds as the metal or metal compound 161_M, the donor level (SOMO level or HOMO level) formed by interaction with the first organic compound 161_1 can be made high-energy, making it easier to donate electrons to the second organic compound 161_2. Therefore, when such a layer 200 is used as the first layer (161a, 161b) of the intermediate layer (160a, 160b), the electron injection barrier from the intermediate layer (160a, 160b) to the first electron transport layer (114a_1, 114b_1) can be reduced, and electrons generated in the intermediate layer 160a can be smoothly injected and transported to the first electron transport layer (114a_1, 114b_1), which is preferable. Furthermore, when such a layer 200 is used as the electron injection layer (115, 115a, 115b), the electron injection barrier from the second electrode 102 to the organic compound layer (103a, 103b) can be reduced, and electrons injected from the second electrode 102 can be smoothly injected and transported to the light-emitting layer (113a, 113b), which is preferable.

[0078] Furthermore, transition metals (metal elements of Groups 3 to 11) and metal elements of Groups 12 to 14, as well as compounds thereof, can also be used for the metal or metal compound 161_M. These substances have low reactivity with oxygen and water in the atmosphere, as well as with water and chemical solutions used in lithography processes. Therefore, when used in light-emitting devices, they have the advantage of being less susceptible to deterioration by water and oxygen, which is a concern when metals with low work functions are used. On the other hand, transition metals (metal elements of Groups 3 to 11) and metal elements of Groups 12 to 14 are stable and have low electron injection properties, which can lead to problems such as reduced luminous efficiency, increased driving voltage, and reduced driving life of light-emitting devices. However, in one embodiment of the present invention, even when a transition metal (a metal element of Groups 3 to 11) or a metal element of Groups 12 to 14 is used for the metal or metal compound 161_M, the metal or metal compound 161_M interacts with the first organic compound 161_1 to form a donor level (SOMO level or HOMO level), and easily donates electrons to the second organic compound having electron-transport properties. Therefore, when such a layer 200 is used for the first layer (161a, 161b) of the intermediate layer (160a, 160b), the electron injection barrier from the intermediate layer (160a, 160b) to the first electron-transport layer (114a_1, 114b_1) can be reduced, and electrons generated in the intermediate layer 160a can be smoothly injected and transported to the first electron-transport layer (114a_1, 114b_1). Furthermore, when such a layer 200 is used for the electron injection layer (115, 115a, 115b), the barrier for electron injection from the second electrode 102 to the organic compound layers (103a, 103b) is reduced, and electrons injected from the second electrode 102 can be smoothly injected and transported to the light-emitting layers (113a, 113b). Furthermore, such a layer 200 is preferable because it can form a layer that is resistant to oxygen and water in the atmosphere, as well as water and chemicals used in a lithography process. Therefore, one embodiment of the present invention can provide a light-emitting device that has excellent moisture resistance, water resistance, oxygen resistance, and chemical resistance, a low driving voltage, and high light-emitting efficiency.

[0079] When the first organic compound 161_1 interacts with a metal or metal compound 161_M, it is preferable that the total number of electrons in the compound and the metal is odd, because this reduces the stabilization energy and allows the donor level (SOMO level or HOMO level) to be at a high energy level. Therefore, when the number of electrons in the compound is even, it is preferable that the metal belongs to an odd group in the periodic table.

[0080] For the first organic compound 161_1 and the second organic compound 161_2, it is preferable to select and use organic compounds that form an exciplex (also called an exciplex). An exciplex is an excited state consisting of two or more substances. In the case of photoexcitation, it is formed when one substance in an excited state interacts with the other substance in a ground state. When the first organic compound 161_1 and the second organic compound 161_2 are a combination that easily interacts with each other, the first organic compound 161_1 easily functions as an electron donor for the second organic compound 161_2 via the metal or metal compound 161_M. In other words, by selecting and using organic compounds that form an exciplex for the first organic compound 161_1 and the second organic compound 161_2, electrons can be easily donated to the second organic compound 161_2 from the donor level formed by the first organic compound 161_1 and the metal or metal compound 161_M.

[0081] The excitation energy level of the exciplex is lower than the singlet excitation level (S1 level) of one of the substances forming the exciplex and the singlet excitation level (S1 level) of the other substance. Therefore, when the first organic compound 161_1 and the second organic compound 161_2 form an exciplex, the emission spectrum of the exciplex is shifted to a longer wavelength than the emission spectrum of the first organic compound 161_1 and the emission spectrum of the second organic compound 161_2.

[0082] Therefore, for example, it is preferable that the peak wavelength of the photoluminescence (PL) spectrum measured using a mixed film containing the first organic compound 161_1 and the second organic compound 161_2 is longer at room temperature than the peak wavelength of the PL spectrum of a single film of the first organic compound 161_1 and the peak wavelength of the PL spectrum of a single film of the second organic compound 161_2. In such a case, it can be said that the first organic compound 161_1 and the second organic compound 161_2 are a combination that forms an exciplex.

[0083] More specifically, the peak wavelength of the PL spectrum of the mixed film containing the first organic compound 161_1 and the second organic compound 161_2 is preferably at least 20 nm, more preferably at least 30 nm, and even more preferably at least 50 nm longer at room temperature than the peak wavelengths of the PL spectrum of a single film of the first organic compound 161_1 and the second organic compound 161_2. Furthermore, when wavelength is converted to energy, the peak energy of the PL spectrum of the mixed film containing the first organic compound 161_1 and the second organic compound 161_2 is preferably at least 0.1 eV, more preferably at least 0.2 eV, and even more preferably at least 0.3 eV lower at room temperature than the peak energy of the PL spectrum of a single film of the first organic compound 161_1 and the second organic compound 161_2. Such a difference can be said to be a combination that allows the first organic compound 161_1 and the second organic compound 161_2 to form an exciplex more efficiently.

[0084] When a PL spectrum has multiple peak wavelengths, the peaks in the PL spectra can be compared using the peak wavelength at the shortest wavelength in the PL spectrum.

[0085] Alternatively, it is preferable that the wavelength of the short-wavelength edge of the PL spectrum of the mixed film containing the first organic compound 161_1 and the second organic compound 161_2 is longer than the wavelength of the short-wavelength edge of the PL spectrum of the first organic compound 161_1 and the wavelength of the short-wavelength edge of the PL spectrum of the second organic compound 161_2 at room temperature. In this case, the first organic compound 161_1 and the second organic compound 161_2 are combined to form an exciplex.

[0086] More specifically, the wavelength of the short-wavelength edge of the PL spectrum of the mixed film containing the first organic compound 161_1 and the second organic compound 161_2 is preferably at least 20 nm, more preferably at least 30 nm, and even more preferably at least 50 nm longer than the wavelengths of the short-wavelength edges of the PL spectrum of the first organic compound 161_1 and the second organic compound 161_2 at room temperature. Furthermore, when wavelength is converted to energy, the energy of the short-wavelength edge of the PL spectrum of the mixed film containing the first organic compound 161_1 and the second organic compound 161_2 is preferably at least 0.1 eV, more preferably at least 0.2 eV, and even more preferably at least 0.3 eV lower than the energy of the short-wavelength edges of the PL spectrum of the first organic compound 161_1 and the second organic compound 161_2 at room temperature. Such a difference can be said to be a combination that allows the first organic compound 161_1 and the second organic compound 161_2 to form an exciplex more efficiently.

[0087] The emission edge on the short wavelength side of the PL spectrum can be calculated by drawing a tangent at the value where the slope on the short wavelength side of the peak (or shoulder peak) observed at the shortest wavelength in the PL spectrum is maximum, and then finding the intersection of this tangent with the horizontal axis or the baseline.

[0088] The transport properties, heat resistance, and solubility of the intermediate layer can be easily adjusted by mixing the first organic compound 161_1 and the second organic compound 161_2. The weight ratio, volume ratio, or molar ratio of the first organic compound 161_1 to the second organic compound 161_2 may be 1:19 to 19:1, preferably 3:7 to 7:3. The emission spectrum of the exciplex formed by the first organic compound 161_1 and the second organic compound 161_2 may be the spectrum of a mixture of the first organic compound 161_1 and the second organic compound 161_2 at a ratio of 1:1.

[0089] Furthermore, it is preferable that the peak wavelength of the photoluminescence (PL) spectrum measured using a mixed film containing the metal or metal compound 161_M, the first organic compound 161_1, and the second organic compound 161_2 is longer at room temperature than the peak wavelength of the PL spectrum of a single film of the first organic compound 161_1 and the peak wavelength of the PL spectrum of a single film of the second organic compound 161_2. In such a case, the first organic compound 161_1 and the second organic compound 161_2 are considered to be a combination that forms an exciplex.

[0090] More specifically, the peak wavelength of the PL spectrum of the mixed film containing the metal or metal compound 161_M, the first organic compound 161_1, and the second organic compound 161_2 is preferably at least 20 nm, more preferably at least 30 nm, and even more preferably at least 50 nm longer at room temperature than the peak wavelengths of the PL spectrum of a single film of the first organic compound 161_1 and the second organic compound 161_2. Furthermore, when wavelength is converted to energy, the peak energy of the PL spectrum of the mixed film containing the metal or metal compound 161_M, the first organic compound 161_1, and the second organic compound 161_2 is preferably at least 0.1 eV, more preferably at least 0.2 eV, and even more preferably at least 0.3 eV lower at room temperature than the peak energy of the PL spectrum of a single film of the first organic compound 161_1 and the second organic compound 161_2. Such a difference can be said to be a combination that allows the first organic compound 161_1 and the second organic compound 161_2 to form an exciplex more efficiently.

[0091] Alternatively, it is preferable that the wavelength of the short-wavelength edge of the PL spectrum of a mixed film containing the metal or metal compound 161_M, the first organic compound 161_1, and the second organic compound 161_2 is longer at room temperature than the wavelength of the short-wavelength edge of the PL spectrum of a single film of the first organic compound 161_1 and the wavelength of the short-wavelength edge of the PL spectrum of a single film of the second organic compound 161_2. In such a case, the first organic compound 161_1 and the second organic compound 161_2 are considered to be a combination that forms an exciplex.

[0092] More specifically, the wavelength of the emission edge on the short wavelength side of the PL spectrum of a mixed film having a metal or metal compound 161_M, a first organic compound 161_1, and a second organic compound 161_2 is preferably at least 20 nm, more preferably at least 30 nm, and even more preferably at least 50 nm longer at room temperature than the wavelength of the emission edge on the short wavelength side of the PL spectrum of a single film of the first organic compound 161_1 and the wavelength of the emission edge on the short wavelength side of the PL spectrum of a single film of the second organic compound 161_2. Furthermore, when wavelength is converted to energy, the energy of the short-wavelength emission edge of the PL spectrum of a mixed film containing the metal or metal compound 161_M, the first organic compound 161_1, and the second organic compound 161_2 is preferably lower by 0.1 eV or more, more preferably 0.2 eV or more, and even more preferably 0.3 eV or more at room temperature than the energy of the short-wavelength emission edge of the PL spectrum of a single film of the first organic compound 161_1 and the energy of the short-wavelength emission edge of the PL spectrum of a single film of the second organic compound 161_2. Such a difference in energy can be said to be a combination that allows the first organic compound 161_1 and the second organic compound 161_2 to form an exciplex more efficiently.

[0093] The first organic compound 161_1 is preferably an organic compound having a LUMO (Lowest Unoccupied Molecular Orbital) level higher than that of the second organic compound 161_2. This facilitates the formation of an exciplex between the first organic compound 161_1 and the second organic compound 161_2, and also facilitates electron donation to the second organic compound 161_2 from the donor level formed by the first organic compound 161_1 and the metal or metal compound 161_M. The first organic compound 161_1 is preferably an organic compound having a LUMO level higher than that of the second organic compound 161_2 by 0.05 eV or more. Alternatively, the first organic compound 161_1 is preferably an organic compound having a LUMO level higher than that of the second organic compound 161_2, preferably by 0.1 eV or more, more preferably by 0.2 eV or more.

[0094] For example, the organic compound used as the first organic compound 161_1 preferably has a LUMO level of -3.0 eV or more and -2.0 eV or less, more preferably -2.7 eV or more and -2.0 eV or less. This makes it easier for the first organic compound 161_1 to donate electrons to the second organic compound 161_2 from the donor level formed by the first organic compound 161_1 and the metal or metal compound 161_M. Furthermore, the organic compound used as the second organic compound 161_2 preferably has a LUMO level of -3.0 eV or more and -2.0 eV or less, more preferably -3.0 eV or more and -2.5 eV or less. This improves the electron transport property of the second organic compound 161_2.

[0095] The first organic compound 161_1 preferably has a higher HOMO level than the second organic compound 161_2. This facilitates the formation of an exciplex between the first organic compound 161_1 and the second organic compound 161_2, and also facilitates electron donation to the second organic compound 161_2 from the donor level formed by the first organic compound 161_1 and the metal or metal compound 161_M. The first organic compound 161_1 preferably has a higher HOMO level than the second organic compound 161_2 by 0.05 eV or more. Alternatively, the first organic compound 161_1 preferably has a higher HOMO level than the second organic compound 161_2 by preferably 0.1 eV or more, more preferably 0.2 eV or more.

[0096] The HOMO and LUMO levels of organic compounds are generally estimated by CV (cyclic voltammetry), photoelectron spectroscopy, optical absorption spectroscopy, inverse photoelectron spectroscopy, etc. When comparing values ​​between different compounds, it is preferable to use values ​​estimated by the same measurement.

[0097] It is also preferable to select and use organic compounds that form a charge-transfer complex as the first organic compound 161_1 and the second organic compound 161_2. A charge-transfer complex is a state consisting of two or more substances, and is formed when a charge is transferred from one substance to another substance through interaction. When the first organic compound 161_1 and the second organic compound 161_2 are combined to easily interact with each other, the first organic compound 161_1 easily functions as an electron donor for the second organic compound 161_2 via the metal or metal compound 161_M. In other words, by selecting and using organic compounds that form a charge-transfer complex as the first organic compound 161_1 and the second organic compound 161_2, electrons can be easily donated to the second organic compound 161_2 from the donor level formed by the first organic compound 161_1 and the metal or metal compound 161_M.

[0098] When a charge-transfer complex is formed, a new absorption band different from that of the substance forming the charge-transfer complex is observed. Therefore, for example, it is preferable that the wavelength of the long-wavelength absorption edge of the absorption spectrum of a mixed film containing the first organic compound 161_1 and the second organic compound 161_2 is longer at room temperature than the wavelength of the long-wavelength absorption edge of the absorption spectrum of a single film of the first organic compound 161_1 and the wavelength of the long-wavelength absorption edge of the absorption spectrum of a single film of the second organic compound 161_2. In such a case, it can be said that the first organic compound 161_1 and the second organic compound 161_2 are a combination that forms a charge-transfer complex.

[0099] More specifically, the wavelength of the absorption edge on the long wavelength side of the absorption spectrum of the mixed film having the first organic compound 161_1 and the second organic compound 161_2 is preferably 30 nm or more, more preferably 50 nm or more, and even more preferably 80 nm or more longer at room temperature than the wavelength of the absorption edge on the long wavelength side of the absorption spectrum of a single film of the first organic compound 161_1 and the wavelength of the absorption edge on the long wavelength side of the absorption spectrum of a single film of the second organic compound 161_2. Furthermore, when wavelength is converted to energy, the energy of the absorption edge on the long wavelength side of the absorption spectrum of the mixed film containing the first organic compound 161_1 and the second organic compound 161_2 is preferably lower by 0.2 eV or more, more preferably 0.3 eV or more, and even more preferably 0.5 eV or more at room temperature than the energy of the absorption edge on the long wavelength side of the absorption spectrum of a single film of the first organic compound 161_1 and the energy of the absorption edge on the long wavelength side of the absorption spectrum of a single film of the second organic compound 161_2. Such a difference in energy can be said to be a combination that allows the first organic compound 161_1 and the second organic compound 161_2 to more efficiently form a charge-transfer complex.

[0100] Furthermore, for example, it is preferable that the wavelength of the absorption edge on the long wavelength side of the absorption spectrum of a mixed film containing the metal or metal compound 161_M, the first organic compound 161_1, and the second organic compound 161_2 is longer at room temperature than the wavelength of the absorption edge on the long wavelength side of the absorption spectrum of a single film of the first organic compound 161_1 and the wavelength of the absorption edge on the long wavelength side of the absorption spectrum of a single film of the second organic compound 161_2. In such a case, it can be said that the combination of the metal or metal compound 161_M, the first organic compound 161_1, and the second organic compound 161_2 forms a charge-transfer complex.

[0101] More specifically, the wavelength of the absorption edge on the long wavelength side of the absorption spectrum of the mixed film having the metal or metal compound 161_M, the first organic compound 161_1, and the second organic compound 161_2 is preferably at least 30 nm, more preferably at least 50 nm, and even more preferably at least 80 nm longer at room temperature than the wavelength of the absorption edge on the long wavelength side of the absorption spectrum of a single film of the first organic compound 161_1 and the wavelength of the absorption edge on the long wavelength side of the absorption spectrum of a single film of the second organic compound 161_2. Furthermore, when wavelength is converted to energy, the energy of the absorption edge on the long wavelength side of the absorption spectrum of the mixed film containing the metal or metal compound 161_M, the first organic compound 161_1, and the second organic compound 161_2 is preferably lower by 0.2 eV or more, more preferably 0.3 eV or more, and even more preferably 0.5 eV or more at room temperature than the energy of the absorption edge on the long wavelength side of the absorption spectrum of a single film of the first organic compound 161_1 and the energy of the absorption edge on the long wavelength side of the absorption spectrum of a single film of the second organic compound 161_2. Such a difference in energy can be said to be a combination that allows the metal or metal compound 161_M, the first organic compound 161_1, and the second organic compound 161_2 to more efficiently form a charge-transfer complex.

[0102] The absorption edge on the long wavelength side of the absorption spectrum can be calculated by drawing a tangent at the value where the absolute value of the slope on the long wavelength side of the peak (or shoulder peak) observed at the longest wavelength in the absorption spectrum is maximum, and then calculating from the intersection of the tangent with the horizontal axis or the baseline.

[0103] The absorption spectrum of the charge-transfer complex formed by the first organic compound 161_1 and the second organic compound 161_2, and the absorption spectrum of the charge-transfer complex formed by the metal or metal compound 161_M, the first organic compound 161_1, and the second organic compound 161_2 may be a spectrum of a mixture of the first organic compound 161_1:second organic compound 161_2=1:1.

[0104] Furthermore, it is preferable to use an organic compound having electron transport properties for each of the first organic compound 161_1 and the second organic compound 161_2. Examples of organic compounds having electron transport properties include organic compounds having a heteroaromatic ring. Specific examples of heteroaromatic rings include π-electron-deficient heteroaromatic rings such as pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, triazine ring, imidazole ring, pyrazole ring, oxazole ring, thiazole ring, and triazole ring, as well as fused rings containing these rings, because they are electrochemically stable and have high electron transport properties.

[0105] The heteroaromatic rings described above each contain a nitrogen atom having an unshared electron pair, and therefore are preferable because they readily interact with the metal or metal compound 161_M.

[0106] In addition, it is preferable to use an organic compound having an electron-donating group as the first organic compound 161_1. By using an organic compound having an electron-donating group as the first organic compound 161_1, the first organic compound 161_1 and the metal or metal compound 161_M tend to interact with each other. In addition, the donor level formed by the first organic compound 161_1 and the metal or metal compound 161_M tends to donate electrons to the second organic compound 161_2.

[0107] Substances that can be used for the metal or metal compound 161_M, the first organic compound 161_1, and the second organic compound 161_2 will be described in detail later.

[0108] Analysis of interactions between metals or metal compounds and organic compounds using quantum chemical calculations Here, a case where a metal or metal compound 161_M, a first organic compound 161_1, and a second organic compound 161_2 interact with each other was analyzed by quantum chemical calculation.

[0109] <Estimation of interactions between metals or metal compounds and organic compounds> First, we performed quantum chemical calculations to analyze the spin density and electrostatic potential (ESP) when a metal or metal compound 161_M, a first organic compound 161_1, and a second organic compound 161_2 interacted with each other. For the calculations, we used silver (Ag) or lithium (Li) atoms as the metal or metal compound 161_M, 4,7-di-1-pyrrolidinyl-1,10-phenanthroline (abbreviated as Pyrrd-Phen) as the first organic compound 161_1, and 2,9-di(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviated as NBPhen) or 2,2'-(2,2'-bipyridine-6,6'-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviated as 6,6'(P-Bqn)2BPy) as the second organic compound 161_2. Pyrrd-Phen and 6,6'(P-Bqn)2BPy form an exciplex. The structural formulae of Pyrrd-Phen, NBPhen, and 6,6'(P-Bqn)2BPy are shown below. Note that the phenanthroline rings in the structural formulae of Pyrrd-Phen and NBPhen are numbered.

[0110] [ka]

[0111] Gaussian09 was used as the quantum chemistry calculation program. Calculations were performed on an HPE SGI8600 computer, and the most stable structures in the ground state of each organic compound and composite material were calculated using density functional theory (DFT). 6-311G(d,p) and LanL2DZ were used as basis functions, and B3LYP was used as the functional. The total energy in DFT is expressed as the sum of potential energy, electrostatic energy between electrons, electron kinetic energy, and exchange-correlation energy, which includes all complex interactions between electrons. DFT approximates the exchange-correlation interaction with a functional (a function of a function) of a single-electron potential expressed in terms of electron density, resulting in highly accurate calculations.

[0112] 3A to 3C show the analysis results of the spin density distribution in the ground state of a composite material of the first organic compound (Pyrrd-Phen) and the metal or metal compound (Ag), a composite material of the second organic compound (NBPhen) and the metal or metal compound (Ag), and a composite material of the first organic compound (Pyrrd-Phen), the second organic compound (NBPhen), and the metal or metal compound (Ag), where Ag is used as the metal or metal compound 161_M, Pyrrd-Phen is used as the first organic compound 161_1, and NBPhen is used as the second organic compound 161_2. Spheres in the figures represent atoms that make up the compounds, and clouds around the atoms have a density value of 0.003 e / a0 3 (e is the elementary charge (1e=1.60218×10 -19 C), a0 is the Bohr radius (1a0=5.29177×10 -11 m)) and indicates the localized state of the doublet ground state in the compound. Note that the ground state of Pyrrd-Phen and the ground state of NBPhen are singlet ground states, so no spin density distribution is observed.

[0113] Figure 3(A) shows the spin density distribution analysis results for the ground state of a composite of the first organic compound (Pyrrd-Phen) and a metal or metal compound (Ag). In the doublet ground state of the composite, the first organic compound (Pyrrd-Phen) interacts with the metal or metal compound (Ag), stabilizing the composite by coordinating with the nitrogen atoms (N) at the 1st and 10th positions, which have unshared electron pairs, in the 1,10-phenanthroline ring of the first organic compound (Pyrrd-Phen). Therefore, as shown in Figure 3(A), some of the spins originating from the unpaired electrons of Ag are distributed to parts of the 1,10-phenanthroline ring of Pyrrd-Phen, particularly the nitrogen atoms (N) at the 1st and 10th positions, which have unshared electron pairs. However, due to the weak interaction, most of the spin density is distributed to Ag. Hereinafter, the nitrogen atoms (N) at the 1st and 10th positions having an unshared electron pair in the 1,10-phenanthroline ring may be referred to as N1 and N10.

[0114] Figure 3(B) shows the spin density distribution analysis results for the ground state of a composite of the second organic compound (NBPhen) and a metal or metal compound (Ag). In the doublet ground state of the composite of the second organic compound (NBPhen) and a metal or metal compound (Ag), the second organic compound (NBPhen) interacts with the metal or metal compound (Ag), and the metal or metal compound (Ag) coordinates to N1 and N10 of the second organic compound (NBPhen), stabilizing the composite. Therefore, as shown in Figure 3(B), some of the spins originating from the unpaired electrons of Ag are distributed in parts of the 1,10-phenanthroline ring of NBPhen, particularly N1 and N10. However, due to the weak interaction, most of the spin density is distributed in Ag.

[0115] Figure 3(C) shows the spin density distribution analysis results for the ground state of a composite of the first organic compound (Pyrrd-Phen), the second organic compound (NBPhen), and a metal or metal compound (Ag). In the doublet ground state of the composite of the first organic compound (Pyrrd-Phen), the second organic compound (NBPhen), and the metal or metal compound (Ag), the first organic compound (Pyrrd-Phen), the second organic compound (NBPhen), and the metal or metal compound (Ag) interact with each other, and the metal or metal compound (Ag) coordinates to the N1 and N10 of the first organic compound (Pyrrd-Phen) and the N1 and N10 of the second organic compound (NBPhen), resulting in stabilization. Therefore, as shown in Figure 3(C), it can be seen that the spin originating from the unpaired electron of Ag is localized in NBPhen. Furthermore, no spin density distribution is observed in Ag. This indicates that NBPhen is in a radical anion state due to the interaction between Pyrrd-Phen, NBPhen, and Ag.

[0116] Figure 4 shows the analysis results of the spin density distribution in the ground state of a composite material consisting of a first organic compound (Pyrrd-Phen), a second organic compound (6,6'(P-Bqn)2BPy), and a metal or metal compound (Li), where Li is used as the metal or metal compound 161_M, Pyrrd-Phen as the first organic compound 161_1, and 6,6'(P-Bqn)2BPy as the second organic compound 161_2. The spheres in the figure represent the atoms that make up the compound, and the clouds around the atoms are in the form of a density threshold (isovalue) of 0.0004 [electrons / au]. 3 ] and indicates the localized state of the doublet ground state in the compound. Note that the ground state of Pyrrd-Phen and the ground state of 6,6'(P-Bqn)2BPy are singlet ground states, so no spin density distribution is observed.

[0117] In the doublet ground state of the composite of the first organic compound (Pyrrd-Phen), the second organic compound (6,6'(P-Bqn)2BPy), and the metal or metal compound (Li), the first organic compound (Pyrrd-Phen) and the second organic compound (6,6'(P-Bqn)2BPy) interact with the metal or metal compound (Li), and the metal or metal compound (Li) coordinates to the N1 and N10 of the first organic compound (Pyrrd-Phen) and the nitrogen atoms with lone electron pairs in the pyridine and benzo[h]quinazoline rings of the second organic compound (6,6'(P-Bqn)2BPy). Therefore, as shown in Figure 4, the spin originating from the unpaired electron of Li is localized in 6,6'(P-Bqn)2BPy. Furthermore, no spin density distribution is observed in Li. This indicates that the second organic compound (6,6'(P-Bqn)2BPy) is in a radical anion state due to the interaction between Pyrrd-Phen, 6,6'(P-Bqn)2BPy, and Li.

[0118] Next, when Ag is used as the metal or metal compound 161_M, Pyrrd-Phen is used as the first organic compound 161_1, and NBPhen is used as the second organic compound 161_2, the analysis results of the electrostatic potential maps for the ground state of the first organic compound (Pyrrd-Phen), the ground state of the second organic compound (NBPhen), the ground state of the composite of the first organic compound (Pyrrd-Phen) and the metal or metal compound (Ag), the ground state of the composite of the second organic compound (NBPhen) and the metal or metal compound (Ag), and the ground state of the composite of the first organic compound (Pyrrd-Phen), the second organic compound (NBPhen), and the metal or metal compound (Ag) are shown in Figures 5(A), 5(B), 6(A), 6(B), and 6(C), respectively. The spheres in the figure represent the atoms that make up the compound, and the clouds around the atoms have a density value of 0.003e / a0 in atomic units. 3The figure shows the ESP in the electron density distribution when the electron density distribution is 1 / 2. The ESP is the interaction energy between a positive point charge with unit charge and the electron distribution of a molecule. The electrostatic potential map shows the ESP in the isoelectron density surface as a color, with regions with negative ESP shown in red and regions with positive ESP shown in blue. Atoms in regions with negative ESP have a negative charge, and atoms in regions with positive ESP have a positive charge. However, because Figures 5 and 6 are grayscale images, the dark red areas (i.e., regions with negative ESP) are surrounded by a thick dotted line, and the dark blue areas (i.e., regions with positive ESP) are surrounded by a thin dashed line to indicate regions with negative and positive ESP.

[0119] Figure 5(A) shows the results of an electrostatic potential map analysis of the ground state of the first organic compound (Pyrrd-Phen). Figure 5(A) shows that in the singlet ground state of the first organic compound (Pyrrd-Phen), the ESPs around N1 and N10 are negative. Furthermore, the Mulliken partial charges of N1 and N10 are both negative, at -0.29e in atomic units. These results indicate that in the singlet ground state of the first organic compound (Pyrrd-Phen), N1 and N10 have negative partial charges.

[0120] Figure 5(B) shows the results of an electrostatic potential map analysis of the second organic compound (NBPhen) in its ground state. Figure 5(B) shows that in the singlet ground state of the second organic compound (NBPhen), the ESPs around N1 and N10 are negative. Furthermore, the Mulliken partial charges of N1 and N10 are both negative, at -0.34e in atomic units. These results indicate that in the singlet ground state of the second organic compound (NBPhen), N1 and N10 have negative partial charges.

[0121] Figure 6(A) shows the electrostatic potential map analysis results for the ground state of a composite of the first organic compound (Pyrrd-Phen) and a metal or metal compound (Ag). In the doublet ground state of the composite of the first organic compound (Pyrrd-Phen) and a metal or metal compound (Ag), the first organic compound (Pyrrd-Phen) interacts with the metal or metal compound (Ag), and the metal or metal compound (Ag) coordinates to N1 and N10 of the first organic compound (Pyrrd-Phen), stabilizing the composite. As a result, as shown in Figure 6(A), the ESPs around N1, N10, and Ag of Pyrrd-Phen are negative. The Mulliken partial charges of N1 and N10 are both negative, at -0.37e in atomic units. The Mulliken partial charge of Ag is also negative, at -0.18e in atomic units. From these facts, it can be seen that in the doublet ground state of the composite material of the first organic compound (Pyrrd-Phen) and the metal or metal compound (Ag), N1, N10, and Ag have negative partial charges.

[0122] Figure 6(B) shows the electrostatic potential map analysis results for the ground state of the composite of the second organic compound (NBPhen) and the metal or metal compound (Ag). In the doublet ground state of the composite of the second organic compound (NBPhen) and the metal or metal compound (Ag), the second organic compound (NBPhen) interacts with the metal or metal compound (Ag), and the metal or metal compound (Ag) coordinates to N1 and N10 of the second organic compound (NBPhen), stabilizing the composite. As a result, as shown in Figure 6(B), the ESPs around N1, N10, and Ag of NBPhen are negative. Furthermore, the Mulliken partial charges of N1 and N10 are -0.45e and -0.39e in atomic units, respectively, and the Mulliken partial charge of the metal or metal compound (Ag) is -0.06e in atomic units, which are negative. From these, it can be seen that in the doublet ground state of the composite material of the second organic compound (NBPhen) and the metal or metal compound (Ag), N1, N10, and Ag have negative partial charges.

[0123] Figure 6(C) shows the electrostatic potential map analysis results for the ground state of a composite of the first organic compound (Pyrrd-Phen), the second organic compound (NBPhen), and a metal or metal compound (Ag). In the doublet ground state of the composite of the first organic compound (Pyrrd-Phen), the second organic compound (NBPhen), and the metal or metal compound (Ag), the first organic compound (Pyrrd-Phen), the second organic compound (NBPhen), and the metal or metal compound (Ag) interact with each other, and the metal or metal compound (Ag) is stabilized by coordination with the N1 and N10 of the first organic compound (Pyrrd-Phen) and the N1 and N10 of the second organic compound (NBPhen). As a result, as shown in Figure 6(C), it can be seen that positive ESPs are mainly distributed around Ag and Pyrrd-Phen, and negative ESPs are mainly distributed around NBPhen. It can also be seen that the ESP around N1 and N10 of NBPhen is negative, while the ESP of Ag is positive. Furthermore, the Mulliken partial charge of N1 and N10 of NBPhen is negative at -0.52e in atomic units, while the Mulliken partial charge of Ag is positive at 0.39e in atomic units. From these results, it can be seen that the charge of the Ag atom is distributed around N1 and N10 of NBPhen.

[0124] Next, Figure 7 shows the results of analyzing the electrostatic potential map in the ground state of a composite material consisting of the first organic compound (Pyrrd-Phen), the second organic compound (6,6'(P-Bqn)2BPy), and the metal or metal compound (Li) when Li is used as the metal or metal compound 161_M, Pyrrd-Phen as the first organic compound 161_1, and 6,6'(P-Bqn)2BPy as the second organic compound 161_2. The spheres in the figure represent the atoms that make up the compound, and the cloud-like matter around the atoms is formed by scattering the electrons with a density threshold (isovalue) of 0.0004 [electrons / au]. 3]. In Fig. 7, to indicate the regions where ESP is negative and the regions where ESP is positive, the dark red areas (i.e., the regions where ESP is negative) are surrounded by dotted lines, and the dark blue areas (i.e., the regions where ESP is positive) are surrounded by dashed lines.

[0125] In the doublet ground state of the composite of the first organic compound (Pyrrd-Phen), the second organic compound (6,6'(P-Bqn)BPy), and the metal or metal compound (Li), the first organic compound (Pyrrd-Phen) and the second organic compound (6,6'(P-Bqn)BPy) interact with the metal or metal compound (Li), and the metal or metal compound (Li) coordinates to the N1 and N10 of the first organic compound (Pyrrd-Phen) and the nitrogen atoms with lone electron pairs in the pyridine ring and benzo[h]quinazoline ring of the second organic compound (6,6'(P-Bqn)BPy), stabilizing the composite. As a result, as shown in Figure 7, it can be seen that positive ESPs are predominantly distributed in Li and Pyrrd-Phen, and negative ESPs are predominantly distributed in 6,6'(P-Bqn)BPy. The pyridine and benzo[h]quinazoline rings of 6,6'(P-Bqn)2BPy have negative ESPs for the nitrogen atoms with lone electron pairs, while the Li atom has a positive ESP. The Mulliken partial charge of the Li atom is +0.691 in atomic units.

[0126] From the above, it can be seen that this combination forms an electron donor by interaction between the first organic compound 161_1 and the metal or metal compound 161_M, and further functions as an electron donor for the second organic compound 161_2 having electron-transporting properties. In one embodiment of the present invention, by using a composite material of this combination for an intermediate layer, an intermediate layer having good electron injection properties and resistance to oxygen and water in the air, as well as water and chemicals used in a lithography process, can be formed, thereby reducing the driving voltage and providing a light-emitting device with high emission efficiency.

[0127] <<Estimation of SOMO levels or stabilization energies>> Next, the stabilization energy when the metal or metal compound 161_M, the first organic compound 161_1, and the second organic compound 161_2 interact with each other, and the SOMO level or HOMO level formed at that time were estimated by quantum chemical calculations. For the calculations, silver (Ag), lithium (Li), zinc (Zn), calcium (Ca), magnesium (Mg), aluminum (Al), copper (Cu), or indium (In) was used as the metal or metal compound 161_M, Pyrrd-Phen was used as the first organic compound 161_1, and 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P), NBPhen, 6,6'(P-Bqn)2BPy, 4',4''''-(1,4-phenylene)bis(2,2':6',2''-terpyridine) (abbreviation: tPy2P), or 2,4,6-tris(2-pyridyl)-1,3,5-triazine (abbreviation: 2Py3Tzn) was used as the second organic compound 161_2. In addition, Pyrrd-Phen and 6,6'(P-Bqn)2BPy are a combination that form an exciplex.

[0128] The structural formulae of Pyrrd-Phen, mPPhen2P, NBPhen, 6,6'(P-Bqn)2BPy, tPy2P, and 2Py3Tzn are shown below. Note that 6,6'(P-Bqn)2BPy, tPy2P, and 2Py3Tzn are organic compounds having two or more heteroaromatic rings, which are bonded or fused to each other and have a total of three or more heteroatoms. On the other hand, NBphen is an organic compound having two or more heteroaromatic rings, which are bonded or fused to each other, but have a total of less than three heteroatoms.

[0129] [ka]

[0130] The quantum chemistry calculation program used was Gaussian09. Calculations were performed on an HPE SGI8600. First, the ground states of the first organic compound 161_1, the second organic compound 161_2, and the metal or metal compound 161_M were calculated using density functional theory (DFT) to determine the most stable structures in the ground state of each compound, as well as the composite of the first organic compound 161_1 and the metal or metal compound 161_M, the composite of the second organic compound 161_2 and the metal or metal compound 161_M, and the composite of the first organic compound 161_1, the second organic compound 161_2, and the metal or metal compound 161_M. The basis functions used were 6-311G(d,p) and LanL2DZ, and the functional used was B3LYP. Next, the stabilization energy was calculated from the difference between the total energy of the composite material of the organic compound and the metal or metal compound and the sum of the total energy of the organic compound and the total energy of the metal or metal compound: (Stabilization energy) = (Total energy of the composite material of the organic compound and the metal or metal compound) - (Total energy of the organic compound) - (Total energy of the metal or metal compound).

[0131] The stabilization energies and HOMO or SOMO levels of the composite materials of the first organic compound 161_1, the second organic compound 161_2, and the metal or metal compound 161_M are calculated and are shown in the tables below. Note that the HOMO and SOMO levels in the tables are calculated values ​​and may differ from the actual measurements.

[0132] The following table shows the results of calculations for a composite material using Zn as the metal or metal compound 161_M, Pyrrd-Phen as the first organic compound 161_1, and mPPhen2P as the second organic compound 161_2. The table also lists the stabilization energy and HOMO level of the composite material of Zn and Pyrrd-Phen, the stabilization energy and HOMO level of the composite material of mPPhen2P and Zn, the HOMO level of Pyrrd-Phen, and the HOMO level of mPPhen2P.

[0133] [Table 1]

[0134] As can be seen from the table above, the stabilization energies of the Zn / Pyrrd-Phen composite and the Zn / mPPhen2P composite are negative, indicating that when Zn interacts with Pyrrd-Phen or mPPhen2P, it is energetically more stable than when they do not interact. However, the difference is slight. Furthermore, the HOMO levels of these composites all differ only slightly from those of Pyrrd-Phen and mPPhen2P, indicating that the interaction between Zn and Pyrrd-Phen or mPPhen2P is weak.

[0135] On the other hand, the above table shows that the stabilization energy of the composite material of Zn, Pyrrd-Phen, and mPPhen2P is smaller than that of the composite material of Zn, Pyrrd-Phen, and that of the composite material of Zn and mPPhen2P, making it energetically stable. Thus, the stabilization energy of the composite material of metal or metal compound 161_M, first organic compound 161_1, and second organic compound 161_2 is preferably −0.50 eV or less, more preferably −1.0 eV or less, −2.0 eV or less, −3.0 eV or less, or −4.0 eV or less. Furthermore, the HOMO level of the composite material of Zn, Pyrrd-Phen, and mPPhen2P is higher than that of Pyrrd-Phen and mPPhen2P, respectively. A high HOMO level is preferable because it provides excellent electron injection properties.

[0136] Next, the results of calculations on a composite material using Ca or Mg as the metal or metal compound 161_M, Pyrrd-Phen as the first organic compound 161_1, and mPPhen2P as the second organic compound 161_2 are shown in the table below.

[0137] [Table 2]

[0138] The above table shows that the stabilization energies of the composite material of Ca, Pyrrd-Phen, and mPPhen2P and the composite material of Mg, Pyrrd-Phen, and mPPhen2P are both -2.0 eV or less. Thus, by using alkaline earth metals (Ca, Mg) as metal or metal compound 161_M, the stabilization energy of the composite material of metal or metal compound 161_M, first organic compound 161_1, and second organic compound 161_2 is -2.0 eV or less, making it more energetically stable and preferable. Furthermore, the HOMO levels of these composite materials are higher than the HOMO levels of Pyrrd-Phen and mPPhen2P shown in Table 1. A high HOMO level is preferable because it provides excellent electron injection properties.

[0139] Next, the results of calculations on a composite material using a metal belonging to an odd group (Group 1, Group 3, Group 5, Group 7, Group 9, Group 11, or Group 13), specifically Li, Al, Ag, Cu, or In, as the metal or metal compound 161_M, Pyrrd-Phen as the first organic compound 161_1, and mPPhen2P as the second organic compound 161_2 are shown in the table below.

[0140] [Table 3]

[0141] The table above shows that the stabilization energy of the composite of Li, Pyrrd-Phen, and mPPhen2P is -3.0 eV or less, that of Al, Pyrrd-Phen, and mPPhen2P is -4.0 eV or less, that of Ag, Pyrrd-Phen, and mPPhen2P is -2.0 eV or less, and that of Cu, Pyrrd-Phen, and mPPhen2P is -1.0 eV or less. Thus, by using metals belonging to the odd-numbered group, the stabilization energies of the composites of the metal and the first organic compound 161_1 and the second organic compound 161_2 are -1.0 eV or less, -2.0 eV or less, -3.0 eV or less, or -4.0 eV or less, respectively, making them more energetically stable and preferable. Furthermore, the SOMO levels of these composites are higher than the HOMO levels of Pyrrd-Phen and mPPhen2P, as shown in Table 1. A high SOMO level is preferable because it provides excellent electron injection properties.

[0142] Next, the results of calculations on a composite material using Li as the metal or metal compound 161_M, Pyrrd-Phen as the first organic compound 161_1, and 6,6'(P-Bqn)2BPy or NBphen as the second organic compound 161_2 are shown in the table below. The table also lists the calculation results for a composite material using Li and Pyrrd-Phen, a composite material using Li and 6,6'(P-Bqn)2BPy, and a composite material using lithium (Li) and NBphen.

[0143] [Table 4]

[0144] The LUMO and HOMO levels of Pyrrd-Phen, 6,6'(P-Bqn)2BPy, tPy2P, 2Py3Tzn, and NBPhen are shown in Table 5. The HOMO and LUMO energy levels in the table are calculated values, and may differ in absolute value from actual measurements.

[0145] [Table 5]

[0146] As shown in Table 4, the stabilization energy of the composite material of Li, Pyrrd-Phen, and 6,6'(P-Bqn)2BPy is negative and its absolute value is large. This indicates that when Pyrrd-Phen, 6,6'(P-Bqn)2BPy, and Li interact, they are more energetically stable than when they do not interact. Furthermore, as shown in Tables 4 and 5, the SOMO level of this composite material is higher than the HOMO levels of Pyrrd-Phen and 6,6'(P-Bqn)2BPy and the difference with their LUMO levels is small, making it preferable for its excellent electron injection properties.

[0147] Furthermore, Table 4 shows that the stabilization energy of the composite material of Li, Pyrrd-Phen, and NBphen is also negative, and that when Pyrrd-Phen, NBphen, and Li interact, the energy is more stable than when they do not interact.

[0148] Furthermore, the composite material of Li and 6,6'(P-Bqn)2BPy has a low SOMO level of -2.88 eV. On the other hand, the composite material of Li, 6,6'(P-Bqn)2BPy, and Pyrrd-Phen has a higher SOMO level of -2.32 eV, resulting in excellent electron injection properties. Furthermore, the composite material of Li and 6,6'(P-Bqn)2BPy has a stabilization energy of -3.07 eV, while the composite material of Li, 6,6'(P-Bqn)2BPy, and Pyrrd-Phen has a stabilization energy of -3.79 eV, making it even more stable.

[0149] The composite of Li and NBPhen has a slightly low SOMO level of -2.96 eV. On the other hand, the composite of Li, NBPhen, and Pyrrd-Phen has a high SOMO level of -2.35 eV, resulting in excellent electron injection properties. The composite of Li and NBPhen also has a stabilization energy of -2.31 eV, while the composite of Li, NBPhen, and Pyrrd-Phen has a stabilization energy of -3.67 eV, making it even more stable.

[0150] Next, the results of calculations on composite materials using a metal belonging to Group 11 and Group 13, specifically Ag or In, as the metal or metal compound 161_M, Pyrrd-Phen as the first organic compound 161_1, and tPy2P, 2Py3Tzn, or NBPhen as the second organic compound 161_2 are shown in the table below.

[0151] [Table 6]

[0152] As can be seen from the table above, the stabilization energy of a composite material consisting of Ag or In, Pyrrd-Phen, and tPy2P, 2Py3Tzn, or NBPhen is negative and its absolute value is large. Thus, the stabilization energy of a composite material consisting of metals belonging to Groups 11 and 13, the first organic compound 161_1, and the second organic compound 161_2 is stable and desirable. Furthermore, the SOMO level formed in this case is high, which is desirable because it has excellent electron injection properties.

[0153] From the above calculation results, it can be said that a composite material using the above metal or metal compound 161_M, the above first organic compound 161_1, and the above second organic compound 161_2 is stable and has excellent electron injection properties, making it suitable for an intermediate layer.

[0154] Considering the manufacturing process of light-emitting devices, organic compound layers of light-emitting devices, especially intermediate layers, are generally formed by vacuum deposition. In this case, it is preferable to use materials that can be easily vacuum-deposited, i.e., materials with low melting points. Metals of Groups 11 and 13 have low melting points and are therefore suitable for vacuum deposition. Furthermore, metals of Groups 11 and 13 are preferred because they are stable to oxygen and water in the atmosphere. Furthermore, vacuum deposition is preferred because it allows for easy mixing of metal atoms and organic compounds.

[0155] Ag and In can also be used as cathode materials. Using the same material for the intermediate layer and the cathode is preferable because it simplifies the fabrication of light-emitting devices and reduces the manufacturing costs of light-emitting devices.

[0156] <Analysis of composite materials of metals and organic compounds> In the light-emitting device of one embodiment of the present invention, the intermediate layer can be measured as a composite material in which the first organic compound 161_1, the second organic compound 161_2, and the metal or metal compound 161_M interact with each other.

[0157] Specifically, a film formed with the same mixing ratio as the intermediate layer used in the light-emitting device is prepared, and the film is measured by mass spectrometry using time-of-flight secondary ion mass spectrometry (ToF-SIMS), laser desorption / ionization mass spectrometry (LDI-MS), matrix-assisted laser desorption / ionization mass spectrometry (MALDI-MS), or the like.

[0158] As a result of this mass analysis, positive ions with a mass-to-charge ratio m / z of M1+M2+M3 or M1+M2+M3+1 can be detected, where M1 is the mass number of the first organic compound 161_1, M2 is the mass number of the second organic compound 161_2, and M3 is the mass number of the metal or metal compound 161_M. When measuring positive ions using these mass spectrometry methods, ions derived from the compound contained in the film, the substituents released from the compound, the compound from which the substituents have been released, and their associated compounds are detected. Therefore, for example, if the mass number of the metal released from the metal compound is 31, positive ions with an m / z of M1+M2+31 or M1+M2+31+1 can be detected.

[0159] Next, substances that can be used for the metal or metal compound 161_M, the first organic compound 161_1, and the second organic compound 161_2 will be described in detail.

[0160] <Metal or Metal Compound 161_M> The metal or metal compound 161_M may be a main group metal or a transition metal.

[0161] Typical metals that can be used include alkali metals (Group 1 elements) such as Li, Na, K, and Cs, alkaline earth metals (Group 2 elements) such as Mg, Ca, and Ba, Group 12 elements such as Zn, earth metals (Group 13 elements) such as Al and In, and Group 14 elements such as Sn, or compounds thereof.

[0162] By using alkali metals and alkaline earth metals and their compounds as the metal or metal compound 161_M, the donor level formed by interaction with the first organic compound 161_1 can be made high in energy, making it easier to donate electrons to the second organic compound 161_2, which is preferable because it allows electrons generated in the intermediate layer to be smoothly injected and transported to the electron transport layer, thereby providing a light-emitting device with low driving voltage and high light emission efficiency.

[0163] Examples of transition metals that can be used include Group 3 elements including lanthanides such as Y, Eu, and Yb, Group 7 elements such as Mn, Group 8 elements such as Fe, Group 9 elements such as Co, Group 10 elements such as Ni and Pt, and Group 11 elements such as Cu, Ag, and Au, as well as compounds thereof. Transition metals are preferred because they have low reactivity with components in the atmosphere such as water and oxygen.

[0164] Among the above, it is more preferable to use a metal belonging to an odd group (Group 1, Group 3, Group 5, Group 7, Group 9, Group 11, or Group 13). Among these odd group transition metals, metals having one electron (unpaired electron) in the outermost orbital are particularly preferable because they easily form a SOMO with the first organic compound 161_1.

[0165] In addition, metals with low melting points that can be formed into films by vacuum deposition are preferred because they can easily form mixed layers with organic compounds. Specifically, for example, metals of Group 11 and Group 13 elements have low melting points and are therefore suitable for vacuum deposition. In addition, metals of Group 11 and Group 13 elements are preferred because they are stable to oxygen and water in the atmosphere.

[0166] <First organic compound 161_1> The first organic compound 161_1 is preferably an organic compound having electron transport properties. Examples of organic compounds having electron transport properties include organic compounds having a heteroaromatic ring. Among heteroaromatic rings, it is more preferable to use an organic compound having a π-electron-deficient heteroaromatic ring, which is electrochemically stable and has high electron transport properties. In order for the first organic compound 161_1 to interact with a metal or the metal compound 161_M and function as an electron donor (electron donor) to the second organic compound 161_2, the π-electron-deficient heteroaromatic ring preferably has an unshared electron pair, and the unshared electron pair preferably has electron-donating properties. That is, the first organic compound 161_1 preferably has a basic π-electron-deficient heteroaromatic ring. Nitrogen has high electronegativity and therefore easily interacts with metals. Furthermore, nitrogen can form conjugated bonds in organic compounds. Therefore, using nitrogen in a molecule, particularly in a heteroaromatic ring, can result in an organic compound with high carrier transport properties. Therefore, the first organic compound 161_1 preferably has a nitrogen-containing heteroaromatic ring. It is more preferable that the heteroaromatic ring is an even-numbered ring, such as a six- or eight-membered ring. This structure allows the unshared electron pair on the nitrogen to avoid conjugation and thus facilitates interaction with the metal or metal compound 161_M. Furthermore, the first organic compound 161_1 preferably has electron transport properties in order to smoothly inject and transport electrons from the intermediate layer to the electron transport layer. Specifically, for example, the first organic compound 161_1 preferably has a pyridine ring.

[0167] Furthermore, the first organic compound 161_1 preferably has two or more π-electron-deficient heteroaromatic rings, and the two or more π-electron-deficient heteroaromatic rings are preferably bonded or fused to each other. This stabilizes the bidentate or polydentate interaction between the metal or metal compound and the first organic compound 161_1 and the second organic compound 161_2, thereby forming an intermediate layer that is resistant to deterioration even after lithography processes involving atmospheric exposure. Therefore, even after lithography processes involving atmospheric exposure of the EL layer, electrons generated in the intermediate layer can be smoothly injected and transported to the adjacent electron transport layer, suppressing increases in driving voltage and enabling the fabrication of tandem light-emitting devices with high luminous efficiency and reliability using lithography processes. Specifically, for example, the first organic compound 161_1 preferably has a heteroaromatic ring containing two or more pyridine rings. Organic compounds with a bipyridine skeleton are particularly preferred because their nitrogen atoms easily coordinate with metals, thereby easily interacting with the metal or metal compound 161_M.

[0168] Furthermore, phenanthroline rings are preferred because they are rigid and highly stable. In particular, organic compounds having a 1,10-phenanthroline ring are preferred because the two nitrogen atoms contained therein can coordinate to metals, making them more likely to interact with metals or metal compounds 161_M.

[0169] The first organic compound 161_1 may have a structure in which multiple phenanthroline rings are linked via single bonds or divalent groups. Specific examples of the divalent groups include alkylene groups and arylene groups.

[0170] An alkylene group is a divalent group formed by removing two hydrogen atoms from an alkane. Specific examples of alkylene groups include divalent groups having a structure formed by removing one more hydrogen atom from the specific examples of alkyl groups described above.

[0171] An arylene group is a divalent group obtained by removing two hydrogen atoms from an aromatic hydrocarbon. Specific examples thereof include divalent groups having a structure in which one hydrogen atom has been removed from the specific examples of the aryl group described above. The arylene group may further have a substituent, and specific examples of the substituent include an alkyl group, an alkoxy group, and a phenyl group.

[0172] Furthermore, it is preferable that the first organic compound 161_1 has an electron-donating substituent. This allows the first organic compound 161_1 to have high HOMO and LUMO levels, thereby increasing the difference between the LUMO levels of the first organic compound 161_1 and the second organic compound 161_2. This allows for more stable interaction between the metal or metal compound 161_M, the first organic compound 161_1, and the second organic compound 161_2. This allows for the formation of an intermediate layer that is resistant to degradation even after a lithography process involving atmospheric exposure. Therefore, even after a lithography process involving atmospheric exposure of the EL layer, electrons generated in the intermediate layer can be smoothly injected and transported to the adjacent electron transport layer. This suppresses an increase in driving voltage, and enables the fabrication of a tandem light-emitting device with high luminous efficiency and high reliability using a lithography process.

[0173] In particular, among phenanthroline rings, organic compounds having a 1,10-phenanthroline ring are preferred because the two nitrogen atoms contained therein can coordinate to metals, and therefore interaction with metals or metal compound 161_M occurs easily.

[0174] Furthermore, it is more preferable to use an organic compound having a phenanthroline ring with an electron-donating group as the first organic compound 161_1. In particular, introducing an electron-donating group into the 1,10-phenanthroline ring can increase the electron density of the phenanthroline ring and improve the efficiency of interaction with the metal or metal compound 161_M. Furthermore, it is preferable to have an electron-donating group at at least one of the 4- and 7-positions of the 1,10-phenanthroline ring. Introducing an electron-donating group into the 4- and 7-positions can increase the electron density of the nitrogen atoms at the 1- and 10-positions, which are para-positions. Furthermore, it is possible to increase the electron density around the nitrogen atoms at the 1- and 10-positions while avoiding steric crowding around them. Therefore, it is preferable because it can facilitate interaction with the metal or metal compound 161_M.

[0175] Furthermore, when the first organic compound 161_1 has high basicity, it can significantly reduce the hole transport property in the first layer 161a of the intermediate layer 160a by interacting with holes, and can prevent holes from being transported from the first layer 161a to the second layer 162a, which is preferable because it is possible to obtain an efficient light-emitting device. Specifically, the acid dissociation constant pKa of the first organic compound 161_1 is preferably 8 or more, more preferably 10 or more, and even more preferably 12 or more.

[0176] Specific examples of the electron-donating group include an alkyl group, an alkoxy group, an aryloxy group, an alkylamino group, an arylamino group, and a heterocyclic amino group. However, the electron-donating group that is preferably introduced into the phenanthroline ring is not limited to these. Any group that can increase the electron density of the phenanthroline ring by introducing it into the phenanthroline ring can be used as the electron-donating group. In addition, the electron-donating group may be introduced into the phenanthroline ring via an arylene group such as a phenylene group, and the arylene group is preferably a p-phenylene group.

[0177] Alkyl groups are groups that are part of alkanes (C n H 2n+2) represents a monovalent group obtained by removing one hydrogen atom from the alkyl group. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a neopentyl group, a hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, a neohexyl group, a 3-methylpentyl group, a 2-methylpentyl group, a 2-ethylbutyl group, a 1,2-dimethylbutyl group, and a 2,3-dimethylbutyl group.

[0178] The alkoxy group refers to a monovalent group in which an alkyl group is bonded to an oxygen atom. Specific examples of the alkoxy group include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, isobutoxy, tert-butoxy, n-pentyloxy, isopentyloxy, sec-pentyloxy, tert-pentyloxy, neopentyloxy, n-hexyloxy, isohexyloxy, sec-hexyloxy, tert-hexyloxy, and neohexyloxy.

[0179] An aryloxy group refers to a monovalent group having an aryl group bonded to an oxygen atom. An aryl group refers to a monovalent group obtained by removing one hydrogen atom from one of the carbon atoms forming the ring of a monocyclic or polycyclic aromatic compound. Specific examples of aryloxy groups include phenoxy, o-tolyloxy, m-tolyloxy, p-tolyloxy, mesityloxy, o-biphenyloxy, m-biphenyloxy, p-biphenyloxy, 1-naphthyloxy, 2-naphthyloxy, and 2-fluorenyloxy. The aryloxy group may further have a substituent, and specific examples of the substituent include an alkyl group, an alkoxy group, and a phenyl group.

[0180] The alkylamino group is a monovalent group formed by removing one hydrogen atom from the nitrogen atom of a primary or secondary amine having one or two alkyl groups bonded to the nitrogen atom. Specific examples of the alkylamino group include a dimethylamino group and a diethylamino group.

[0181] An arylamino group is a monovalent group formed by removing one hydrogen atom from the nitrogen atom of a primary amine or secondary amine having one or two aryl groups bonded to the nitrogen atom. Specific examples of the arylamino group include a diphenylamino group, a bis(α-naphthyl)amino group, and a bis(m-tolyl)amino group. The arylamino group may further have a substituent, and specific examples of the substituent include an alkyl group, an alkoxy group, and a phenyl group.

[0182] An amino group having both an alkyl group and an aryl group bonded to a nitrogen atom can be called either an alkylamino group or an arylamino group. Specific examples of such amino groups include an N-methyl-N-phenylamino group.

[0183] The heterocyclic amino group refers to a monovalent group obtained by removing one hydrogen atom from one of the nitrogen atoms forming the ring of a heterocyclic amine. Here, the heterocyclic amine refers to a monocyclic or polycyclic heterocyclic compound in which at least one of the atoms forming the ring is a nitrogen atom to which a hydrogen atom is bonded. Specific examples of the heterocyclic amino group include groups represented by the following structural formulas (R-1) to (R-27). The heterocyclic amino group may further have a substituent, and specific examples of the substituent include an alkyl group, an alkoxy group, and a phenyl group.

[0184] [ka]

[0185] In addition, when the heterocyclic amino group has aromaticity, the unshared electron pair of the nitrogen atom contributes to aromaticity, and the electron donating ability to the phenanthroline ring may be reduced compared to when the unshared electron pair of the nitrogen atom does not contribute to aromaticity.Therefore, among the above-mentioned heterocyclic amino groups, heterocyclic amino groups in which the unshared electron pair of the nitrogen atom does not contribute to aromaticity are more preferred.Specifically, groups represented by structural formula (R-1), (R-2), (R-3), (R-4), (R-5), (R-8), (R-9), (R-10), (R-12), (R-14), (R-15), (R-16), (R-17), (R-18) or (R-22) are more preferred as electron donating groups. Among these, groups represented by structural formula (R-3), (R-4), (R-8) or (R-22) are preferred because they have high electron donating properties and can further increase the electron density of the phenanthroline ring.

[0186] Specific examples of the electron-donating group include groups represented by the following structural formulas (R-28) and (R-29).

[0187] [ka]

[0188] The organic compound having a phenanthroline ring that can be used as the first organic compound 161_1 may have both the electron-donating group described above and other substituents. Introducing an electron-withdrawing group (e.g., a cyano group or a fluoro group) into the phenanthroline ring is undesirable because it reduces the electron density of the phenanthroline ring and may make it difficult to interact with the metal or metal compound 161_M. In addition to the electron-donating group described above, specific examples of substituents that can be introduced into the phenanthroline ring include aryl groups. Specific examples of aryl groups include phenyl groups, o-tolyl groups, m-tolyl groups, p-tolyl groups, mesityl groups, o-biphenyl groups, m-biphenyl groups, p-biphenyl groups, 1-naphthyl groups, 2-naphthyl groups, and 2-fluorenyl groups. The aryl group may further have a substituent, and specific examples of the substituent include alkyl groups, alkoxy groups, and phenyl groups.

[0189] The first organic compound 161_1 may have a structure in which multiple phenanthroline rings are linked via single bonds or divalent groups. Specific examples of the divalent groups include alkylene groups and arylene groups.

[0190] An alkylene group is a divalent group formed by removing two hydrogen atoms from an alkane. Specific examples of alkylene groups include divalent groups having a structure formed by removing one more hydrogen atom from the specific examples of alkyl groups described above.

[0191] An arylene group is a divalent group obtained by removing two hydrogen atoms from an aromatic hydrocarbon. Specific examples thereof include divalent groups having a structure in which one hydrogen atom has been removed from the specific examples of the aryl group described above. The arylene group may further have a substituent, and specific examples of the substituent include an alkyl group, an alkoxy group, and a phenyl group.

[0192] Specific examples of organic compounds that can be used as the first organic compound 161_1 are shown in structural formulas (100) to (112). Note that the organic compounds that can be used as the first organic compound 161_1 are not limited to these.

[0193] [ka]

[0194] The structural formula (100) is Pyrrd-Phen, the structural formula (101) is 4,7-bis[4-(1-pyrrolidinyl)phenyl]-1,10-phenanthroline (abbreviation: PrdP2Phen), the structural formula (104) is 4,7-bis(1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidin-1-yl)-1,10-phenanthroline (abbreviation: 4,7hpp2Phen), the structural formula (105) is 4,7-di(2,3,3a,4,5,6,7,7a-octahydro-1H-isoindol-2-yl)-1,10-phenanthroline (abbreviation: Hid2Phen), and the structural formula (107) is 2,2' -(1,3-phenylene)bis[9-(1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidin-1-yl)-1,10-phenanthroline] (abbreviation: mhppPhen2P), structural formula (108) is 2-(1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidin-1-yl)-9-phenyl-1,10-phenanthroline (abbreviation: 9Ph-2hppPhen), and structural formula (109) is 2,9-bis(1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidin-1-yl)-1,10-phenanthroline (abbreviation: 2,9hpp2Phen).

[0195] It is preferable that the minimum value of the ESP of the first organic compound 161_1 is small (a negative value with a large absolute value), since this increases the efficiency of the interaction with the metal or metal compound 161_M. In organic compounds having a phenanthroline ring, the ESP around the nitrogen atom of the phenanthroline ring tends to be negative. However, by introducing an electron-donating group into the phenanthroline ring, the ESP around the nitrogen atom of the phenanthroline ring can be further reduced (the absolute value of the negative value can be increased). The ESP is the interaction energy between a positive point charge with a unit charge and the electron distribution of the molecule. The value of ESP also varies depending on the electron density threshold. To increase the efficiency of the interaction with the metal or metal compound 161_M, it is preferable that the minimum value of the ESP of the first organic compound 161_1 is smaller (larger in the negative direction) than the minimum value of the ESP of a phenanthroline ring without a substituent. Specifically, when the threshold of the electron density distribution in the atomic unit system is set to 0.0004 e / a0 3 When this is done, the minimum value of ESP is -0.085E h (E h is the Hartree energy (1E h =27.211 eV) or less is preferred, -0.090E h It is more preferable that the threshold of the electron density distribution is 0.003e / a0 or less. 3 When this is done, the minimum value of ESP is -0.12E h Less than or equal to -0.13E is preferable h The following is even more preferred:

[0196] <<Estimation of properties by quantum chemical calculations>> The minimum ESP values ​​of the organic compounds represented by structural formulas (100) to (109) were estimated by quantum chemical calculations. For comparison, the minimum ESP values ​​of BPhen, mPPhen2P, NBPhen, and Phen were also estimated in the same manner. The structural formulas of BPhen, mPPhen2P, NBPhen, and Phen are shown below.

[0197] [ka]

[0198] The quantum chemistry calculation program used was Gaussian09. Calculations were performed using an SGI8600 manufactured by HPE. The most stable structure of the first organic compound 161_1 in the ground state was calculated using density functional theory (DFT). 6-311G(d,p) was used as the basis set, and B3LYP was used as the functional.

[0199] Table 7 shows the estimated minimum ESP value in the ground state of the first organic compound 161_1. Note that ESP is the interaction energy between a positive point charge with a unit charge and the electron distribution of the molecule. The ESP value also changes depending on the threshold value of the electron density. In Table 7, the density value in atomic units is 0.0004e / a0 3 or 0.003e / a0 3 The ESP in the electron density distribution when

[0200] [Table 7]

[0201] From the above table, the organic compounds represented by the structural formulas (100) to (105) have an electron density distribution threshold of 0.0004e / a0 3 When this is done, the minimum value of ESP is -0.085E h The minimum ESP value of the organic compounds represented by the structural formulas (106) to (109) is −0.085E h It turned out to be larger.

[0202] It can be seen that the organic compounds represented by structural formulas (100) to (105) have the most preferable values ​​because they have electron-donating groups at the 4- and 7-positions of the 1,10-phenanthroline ring.

[0203] The organic compound represented by structural formula (106) has electron-donating groups at the 4th and 7th positions of the 1,10-phenanthroline ring, but uses an N-carbazolyl group as the electron-donating group. In the N-carbazolyl group, the unshared electron pair of the nitrogen atom contributes to aromaticity, so compared to groups in which the unshared electron pair of the nitrogen atom does not contribute to aromaticity, the electron-donating ability to the phenanthroline ring is reduced, making it difficult to lower the minimum ESP value, resulting in the above results.

[0204] The organic compounds represented by structural formulas (107) to (109) are organic compounds having electron-donating groups at the 2- and 9-positions of the 1,10-phenanthroline ring. When the electron-donating groups are introduced at the 2- and 9-positions of the 1,10-phenanthroline ring, the electron-donating ability to the nitrogens at the 1- and 10-positions of the 1,10-phenanthroline ring is lower than when the electron-donating groups are introduced at the 4- and 7-positions. Therefore, the substitution positions of the electron-donating groups on the 1,10-phenanthroline ring are preferably the 4- and 7-positions.

[0205] Furthermore, when the first organic compound 161_1 has high basicity, it can significantly reduce the hole transport property in the first layer 161a of the intermediate layer 160a by interacting with holes, and can prevent holes from being transported from the first layer 161a to the second layer 162a, which is preferable because it is possible to obtain an efficient light-emitting device. Specifically, the acid dissociation constant pKa of the first organic compound 161_1 is preferably 8 or more, more preferably 10 or more, and even more preferably 12 or more.

[0206] If the acid dissociation constant pKa of an organic compound is unknown, the acid dissociation constant pKa of each skeleton of the organic compound can be examined, and the largest acid dissociation constant pKa selected from these can be regarded as the acid dissociation constant pKa of the organic compound.

[0207] Alternatively, the acid dissociation constant may be calculated. For example, the acid dissociation constant pKa can be calculated using the following calculation method.

[0208] The initial molecular structure of each molecule used as a calculation model is the most stable structure (singlet ground state) obtained from first-principles calculations.

[0209] The first-principles calculations were performed using Schrödinger's quantum chemistry calculation software, Jaguar, to calculate the most stable structure in the singlet ground state using density functional theory (DFT). The basis set used was 6-31G**, and the functional was B3LYP-D3. The structure used for the quantum chemistry calculations was sampled using Schrödinger's Maestro GUI, with conformational analysis performed using mixed torsional / low-mode sampling.

[0210] For pKa calculations, one or more atoms of each molecule are designated as basic sites, and a Macro Model is used to search for the stable structure of the protonated molecule in water. A conformational search is performed using the OPLS2005 force field, and the lowest energy conformer is used. Using the Jaguar pKa calculation module, the structure is optimized with B3LYP / 6-31G*, followed by a single-point calculation with cc-pVTZ(+), and the pKa value is calculated using empirical corrections for functional groups. For molecules with one or more atoms designated as basic sites, the largest value obtained is used as the pKa value. The obtained pKa value is shown below.

[0211] The acid dissociation constant pKa of 2,9hpp2Phen is 13.35, the acid dissociation constant pKa of 4,7hpp2Phen is 13.42, the acid dissociation constant pKa of Pyrrd-Phen is 11.23, the acid dissociation constant pKa of mPPhen2P is 5.16, the acid dissociation constant pKa of NBPhen is 5.59, and the acid dissociation constant pKa of BPhen is 5.62.

[0212] <Second organic compound 161_2> The second organic compound 161_2 is preferably an organic compound having an electron transporting property. The organic compound having an electron transporting property is preferably an organic compound having an electron mobility of 1×10 at a square root of an electric field strength [V / cm] of 600. -7 cm2 / Vs or more, preferably 1×10 -6 cm 2 A substance having an electron mobility of 1 / Vs or more is preferred. Note that other substances can also be used as long as they have a higher electron transporting property than holes.

[0213] In addition, as an organic compound having electron transport properties, an organic compound having a π-electron-deficient heteroaromatic ring is preferred. Examples of the π-electron-deficient heteroaromatic ring include a heteroaromatic ring having an azole skeleton (imidazole ring, pyrazole ring, oxazole ring, thiazole ring, triazole ring, oxadiazole ring, thiadiazole ring), a heteroaromatic ring having a pyridine skeleton, a heteroaromatic ring having a diazine skeleton, and a heteroaromatic ring having a triazine skeleton, and in particular, a diazine ring (pyrazine ring, pyrimidine ring, pyridazine ring) or a triazine ring is preferred because of its electrochemical stability and high electron transport properties.

[0214] An example of an organic compound that can be used for the second organic compound 161_2 is an organic compound represented by the following general formula (G1-1).

[0215] [ka]

[0216] In the above general formula (G1-1), A 1 , A 2 and A 3 each independently represents a substituted or unsubstituted heteroaromatic ring having 1 to 30 carbon atoms; A 1 , A 2 and A 3 may be fused together to form a condensed ring.

[0217] The organic compound represented by general formula (G1-1) has a conjugated double bond in which N atoms on each heteroaromatic ring are arranged in the order of NCCN, and has the function of interacting with metals at a tridentate or higher level. Since organic compounds having such a structure easily interact with metals, they can be suitably used as the second organic compound 161_2.

[0218] In the above general formula (G1-1), A 1 , A 2 and A 3 Examples of the substituted or unsubstituted heteroaromatic ring having 1 to 30 carbon atoms represented by the formula (I) include heteroaromatic rings having a pyridine skeleton (pyridine ring, quinoline ring, isoquinoline ring, naphthyridine ring, bipyridine ring, phenanthridine ring, phenanthroline ring, anthridine ring, azafluoranthene ring), heteroaromatic rings having a diazine skeleton (pyrazine ring, pyrimidine ring, pyridazine ring, quinoxaline ring, benzoquinoxaline ring, dibenzoquinoxaline ring, quinazoline ring, benzoquinazoline ring, phthalazine ring, cinnoline ring, pteridine ring, phenazine ring), heteroaromatic rings having a triazine skeleton, heteroaromatic rings having an azole skeleton (imidazole ring, benzimidazole ring, pyrazole ring, oxazole ring, thiazole ring, triazole ring, oxadiazole ring, thiadiazole ring), etc., provided that A 1 , A 2 and A 3 The substituted or unsubstituted heteroaromatic ring having 1 to 30 carbon atoms represented by the formula A is not limited to these. 1 , A 2 and A 3 may form a condensed ring with each other. For example, A 1 and A 2 may be bonded to each other to form a phenanthroline ring.

[0219] Moreover, examples of organic compounds that can be used for the second organic compound 161_2 include organic compounds represented by the following general formula (G2-1).

[0220] [ka]

[0221] In general formula (G2-1), X 1 ~X 6each independently represents carbon (C) or nitrogen (N), and carbon (C) is bonded to hydrogen, an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms; R 1 ~R 4 each independently represents hydrogen, an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms. 1 ~X 6 may be bonded to each other directly or via a divalent group to form a fused ring. Specific examples of the divalent group include an alkylene group and an arylene group.

[0222] It is more preferable that the organic compound having a tridentate or higher dentate structure and the ability to interact with metals, such as the organic compound represented by general formula (G2-1), has at least one heteroaromatic ring having a pyridine skeleton, a heteroaromatic ring having a diazine skeleton, or a heteroaromatic ring having a triazine skeleton. These rings have excellent electrochemical stability, allowing for the provision of highly reliable light-emitting devices. Furthermore, their excellent electron transport properties allow for the provision of light-emitting devices with reduced driving voltages.

[0223] Moreover, examples of organic compounds that can be used for the second organic compound 161_2 include organic compounds represented by the following general formula (G3-1).

[0224] [ka]

[0225] In general formula (G3-1), X 1 ~X 4each independently represents carbon (C) or nitrogen (N), and carbon (C) is bonded to hydrogen, an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms; R 1 ~R 6 each independently represents hydrogen, an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms.

[0226] Moreover, examples of organic compounds that can be used for the second organic compound 161_2 include organic compounds represented by the following general formula (G4-1).

[0227] [ka]

[0228] In general formula (G4-1), X 1 ~X 5 each independently represents carbon (C) or nitrogen (N), and carbon (C) is bonded to hydrogen, an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms; R 1 ~R 6 each independently represents hydrogen, an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms.

[0229] Organic compounds having a pyridine skeleton are preferred because they have a high LUMO level. 1 and X 2When represents carbon, the organic compound has a pyridine skeleton, which gives it a high LUMO level, and when it interacts with a metal, it can form a composite material with a high SOMO level. That is, an organic compound that has a pyridine ring and the ability to interact with a metal at a tridentate or higher level can form an intermediate layer with high electron injection properties by interacting with a metal.

[0230] In addition, organic compounds having a diazine skeleton or a triazine skeleton are preferred because they are electrochemically stable and have high electron transport properties. 1 and X 2 When at least one of represents nitrogen, the organic compound has a diazine skeleton or a triazine skeleton, and is therefore electrochemically stable and has high electron transport properties, and can form a stable composite material with high electron transport properties when interacting with a metal. That is, an organic compound having a diazine ring or a triazine ring and having the function of interacting at a tridentate or higher level can form a highly reliable intermediate layer by interacting with a metal.

[0231] Moreover, examples of organic compounds that can be used for the second organic compound 161_2 include organic compounds represented by the following general formula (G1-2).

[0232] [ka]

[0233] In the above general formula (G1-2), A 1 and A 2 each independently represents a substituted or unsubstituted heteroaromatic ring having 1 to 30 carbon atoms; A 1 and A 2 may form a condensed ring with each other, A 1 has two or more nitrogen atoms.

[0234] The organic compound represented by general formula (G1-2) has a conjugated double bond in which N atoms on a heteroaromatic ring are arranged in the order of NCCN, and has the ability to interact with metals at a bidentate or higher level. Organic compounds with such a structure easily interact with metals, making them suitable for use in intermediate layers.

[0235] In the above general formula (G1-2), A 1 Examples of the substituted or unsubstituted heteroaromatic ring having 1 to 30 carbon atoms represented by the formula (I) include heteroaromatic rings having a diazine skeleton (pyrazine ring, pyrimidine ring, pyridazine ring, quinoxaline ring, benzoquinoxaline ring, dibenzoquinoxaline ring, quinazoline ring, benzoquinazoline ring, phthalazine ring, cinnoline ring, pteridine ring, phenazine ring), heteroaromatic rings having a triazine skeleton, and heteroaromatic rings having an azole skeleton (imidazole ring, benzimidazole ring, pyrazole ring, oxazole ring, thiazole ring, triazole ring, oxadiazole ring, thiadiazole ring), etc. 2 Examples of the substituted or unsubstituted heteroaromatic ring having 1 to 30 carbon atoms represented by the formula (I) include heteroaromatic rings having a pyridine skeleton (pyridine ring, quinoline ring, isoquinoline ring, naphthyridine ring, bipyridine ring, phenanthridine ring, phenanthroline ring, anthridine ring, azafluoranthene ring), heteroaromatic rings having a diazine skeleton (pyrazine ring, pyrimidine ring, pyridazine ring, quinoxaline ring, benzoquinoxaline ring, dibenzoquinoxaline ring, quinazoline ring, benzoquinazoline ring, phthalazine ring, cinnoline ring, pteridine ring, phenazine ring), heteroaromatic rings having a triazine skeleton, heteroaromatic rings having an azole skeleton (imidazole ring, benzimidazole ring, pyrazole ring, oxazole ring, thiazole ring, triazole ring, oxadiazole ring, thiadiazole ring), etc., provided that A 1 and A 2 The substituted or unsubstituted heteroaromatic ring having 1 to 30 carbon atoms represented by the formula A is not limited to these. 1 , and A 2 may form a condensed ring with each other. For example, A 1 and A 2may be bonded to each other to form a pyrazinoquinoxaline ring.

[0236] Moreover, examples of organic compounds that can be used for the second organic compound 161_2 include organic compounds represented by the following general formula (G2-2).

[0237] [ka]

[0238] In general formula (G2-2), X 1 ~X 4 at least one of represents nitrogen (N), and the others each independently represent carbon (C) or nitrogen (N), and the carbon (C) is bonded to hydrogen, an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms; R 1 ~R 4 each independently represents hydrogen, an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms. 1 ~X 4 may be bonded to each other directly or via a divalent group to form a fused ring. Specific examples of the divalent group include an alkylene group and an arylene group.

[0239] It is more preferable that the organic compound having the function of interacting with metals at a bidentate or higher level, such as the organic compound represented by general formula (G2-2), has a heteroaromatic ring having a diazine skeleton or a heteroaromatic ring having a triazine skeleton. These rings have excellent electrochemical stability, allowing for the provision of highly reliable light-emitting devices. Furthermore, their excellent electron transport properties allow for the provision of light-emitting devices with reduced driving voltages.

[0240] As an example of an organic compound that can be used for the second organic compound 161_2, an organic compound represented by the following general formula (G3-2) can be used.

[0241] [ka]

[0242] In general formula (G3-2), X 1 or X 2 one of the groups represents nitrogen (N), and the other represents carbon (C) or nitrogen (N), and the carbon (C) is bonded to hydrogen, an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms; R 1 ~R 6 each independently represents hydrogen, an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms.

[0243] Moreover, examples of organic compounds that can be used for the second organic compound 161_2 include organic compounds represented by the following general formula (G4-2).

[0244] [ka]

[0245] In general formula (G4-2), X 1 ~X 3 at least one of represents nitrogen (N), and the others each independently represent carbon (C) or nitrogen (N), and the carbon (C) is bonded to hydrogen, an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms; R1 ~R 5 each independently represents hydrogen, an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms.

[0246] Organic compounds having a pyridine skeleton are preferred because they have a high LUMO level. For example, X in general formulas (G2-2) and (G4-2) 1 and X 2 and X in general formula (G3-2) 1 When represents carbon, the organic compound has a pyridine skeleton, which gives it a high LUMO level, and when it interacts with a metal, it can form a composite material with a high SOMO level. That is, an organic compound that has a pyridine ring and the ability to interact at two or more dentates can form an intermediate layer with high electron injection properties by interacting with a metal.

[0247] In addition, organic compounds having a diazine skeleton or a triazine skeleton are preferred because they are electrochemically stable and have high electron transport properties. 1 and X 2 and X in general formula (G3-2) 1 When represents nitrogen, the organic compound has a diazine skeleton or a triazine skeleton, and therefore is electrochemically stable and has high electron transport properties, and can form a stable composite material with high electron transport properties when interacting with a metal. That is, an organic compound having a diazine ring or a triazine ring and having the function of interacting at a bidentate or higher level can form a highly reliable intermediate layer by interacting with a metal.

[0248] More specific examples of organic compounds that can be used for the second organic compound 161_2 and the organic compounds represented by the above general formulas (G1-1) to (G4-2) are shown in general formulas (250) to (268) below.

[0249] [ka]

[0250] [ka]

[0251] In the general formulas (250) to (268), R 11 ~R 162 each independently represents hydrogen, an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 to 30 carbon atoms.

[0252] In addition, examples of substituents that can be applied to the above-mentioned general formulae (G1-1) to (G4-2) and general formulae (250) to (268) include alkyl groups having 1 to 10 carbon atoms, cycloalkyl groups having 3 to 10 carbon atoms, aryl groups having 6 to 30 carbon atoms, arylene groups having 6 to 30 carbon atoms, and heteroaryl groups having 1 to 30 carbon atoms. Some or all of the hydrogen atoms may be deuterium. In addition, the groups that can be applied to the above-mentioned general formulae are not limited to the following specific examples.

[0253] Specific examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a neopentyl group, a hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, a neohexyl group, a 3-methylpentyl group, a 2-methylpentyl group, a 2-ethylbutyl group, a 1,2-dimethylbutyl group, a 2,3-dimethylbutyl group, and a 1-ethylhexyl group.

[0254] Specific examples of the cycloalkyl group having 3 to 10 carbon atoms include a cyclopropyl group, a cyclobutyl group, a methylcyclobutyl group, a cyclopentyl group, a methylcyclopentyl group, an isopropylcyclopentyl group, a tert-butylcyclopropyl group, a cyclohexyl group, a methylcyclohexyl group, an isopropylcyclohexyl group, a tert-butylcyclohexyl group, a cycloheptyl group, a methylcycloheptyl group, an isopropylcycloheptyl group, a cyclooctyl group, a methylcyclooctyl group, an isopropylcyclohexyl group, a cyclononyl group, a methylcyclononyl group, a cyclodecyl group, and an adamantyl group.

[0255] Specific examples of the aryl group having 6 to 30 carbon atoms include a phenyl group, an o-tolyl group, an m-tolyl group, a p-tolyl group, a mesityl group, an o-biphenyl group, an m-biphenyl group, a p-biphenyl group, a 1-naphthyl group, a 2-naphthyl group, a fluorenyl group, a 9,9-dimethylfluorenyl group, a spirobifluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, etc. When the aryl group having 6 to 30 carbon atoms has a substituent, examples of the substituent include an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a phenyl group, etc.

[0256] Specific examples of the arylene group having 6 to 30 carbon atoms include a phenylene group, a biphenyl-diyl group, a naphthalene-diyl group, a fluorene-diyl group, an acenaphthene-diyl group, an anthracene-diyl group, a phenanthrene-diyl group, a terphenyl-diyl group, a triphenylene-diyl group, a phenanthrene-diyl group, a tetracene-yl group, a benzanthracene-diyl group, a pyrene-diyl group, and a spirobi[9H-fluorene]-diyl group. When the arylene group having 6 to 30 carbon atoms has a substituent, examples of the substituent include an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, and a phenyl group.

[0257] The heteroaryl group having 1 to 30 carbon atoms represents a monovalent group obtained by removing one hydrogen atom from one of the carbon atoms constituting the ring of a monocyclic or polycyclic heterocyclic aromatic compound having 1 to 30 carbon atoms. Specific examples of the heteroaryl group having 1 to 30 carbon atoms include a 1,3,5-triazin-2-yl group, a 1,2,4-triazin-3-yl group, a pyrimidin-4-yl group, a pyrazin-2-yl group, a 2-pyridyl group, a 3-pyridyl group, a 4-pyridyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzonaphthofuranyl group, a benzonaphthothiophenyl group, an indolocarbazolyl group, a benzofurocarbazolyl group, a benzothienocarbazolyl group, an indenocarbazolyl group, and a dibenzocarbazolyl group. When the heteroaryl group has a substituent, examples of the substituent include an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, and a phenyl group.

[0258] Specific examples of organic compounds that can be used for the second organic compound 161_2 and organic compounds represented by the above general formulas (G1-1) to (G4-2) are shown below.

[0259] [ka]

[0260] [ka]

[0261] [ka]

[0262] The organic compound that can be used as the second organic compound 161_2 is not limited to the above, and an organic compound that has electron transport properties and forms an exciplex with the first organic compound 161_1 can be used as the second organic compound 161_2.

[0263] Specific examples of organic compounds having electron transport properties include 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-1,2,4-triazole (abbreviation: OXD-7), and 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-1,2,4-triazole (abbreviation: OXD-7). Organic compounds with an azole skeleton, such as 2-[3-(dibenzothiophen-4-yl)phenyl]-9H-carbazole (abbreviation: CO11), 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), and 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOs), and 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridin phenanthroline (abbreviation: BPhen), 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), bathophenanthroline (abbreviation: BPhen), bathocuproine (abbreviation: BCP), 2,9-di(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBPhen), 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P), 4,7-diphenyl-2,9-bis(4-[1-phenyl-1H-benzo[d]i The organic compounds containing heteroaromatic rings with a pyridine skeleton, such as 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-{3-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}dibenzo[f,h]quinoxaline (abbreviation: 2mPCCzPDBq), 2-[4'-(9-phenyl-9H-carbazol-3-yl)-3,1'-biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mpPCBPDBq), 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-I II), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as 7mDBTPDBq-II), and 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as 6mDBTPDBq-II), 9-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviated as 9mDBtBPNfpr), 9-[3'-(dibenzothiophen-4-yl)biphenyl-4 ... Furo[2,3-b]pyrazine (abbreviation: 9pmDBtBPNfpr), 4,6-bis[3-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(dibenzothiophen-4-yl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), 9,9'-[pyrimidine-4,6-diylbis(biphenyl-3,3'-diyl)]bis(9H-carbazole) (abbreviation: 4,6mCzB P2Pm), 8-(biphenyl-4-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviated as 8BP-4mDBtPBfpm), 8-(1,1':4',1''-terphenyl-3-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviated as 8mpTP-4mDBtPBfpm), 8-(1,1':4',1''-terphenyl-3-yl-2,4,5,6,2',3',5',6',2'',3'',4'',5'',6''-d13)-4-[3-(dibenzothiophen-4-yl-1,2,3,6,7,8,9-d7)phenyl-2,4,6-d3]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm-d, 23), 3,8-bis[3-(dibenzothiophen-4-yl)phenyl]benzofuro[2,3-b]pyrazine (abbreviated as 3,8mDBtP2Bfpr), 4,8-bis[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviated as 4,8mDBtP2Bfpm), 8-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[3,2-d]pyrimidine (abbreviated as 8mDBtBPNfpm), 8-[(2,2'-binaphthalen)-6-yl]-4-[3-(dibenzo Thiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8(βN2)-4mDBtPBfpm), 2,2'-(pyridine-2,6-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 2,6(P-Bqn)2Py), 2,2'-(2,2'-bipyridine-6,6'-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 6,6'(P-Bqn)2BPy), 2,2'-(pyridine-2,6-diyl)bis{4-[4-(2-naphthyl)phenyl]-6-phenylpyrimidine} (abbreviation: 2,6(N P-PPm)2Py), 6-(biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviated as 6mBP-4Cz2PPm), 2,6-bis(4-naphthalen-1-ylphenyl)-4-[4-(3-pyridyl)phenyl]pyrimidine (abbreviated as 2,4NP-6PyPPm), 4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenyl-6-(biphenyl-4-yl)pyrimidine (abbreviated as 6BP-4Cz2PPm), 7-[4-(9-phenyl-9H-carbazole organic compounds with a diazine skeleton, such as 2-(biphenyl-4-yl)-4-phenyl-6-(9,9'-spirobi[9H-fluoren-2-yl)-1,3,5-triazine (abbreviation: BP-SFTzn), 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-8-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn), 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-8-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn), and 2-{3-[3-(benzo[b]naphtho[1,2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn-02), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), 2-[3'-(9,9-diphenyl Methyl-9H-fluoren-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn), 5-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviation: mINc(II)PTzn), 2-{3-[3-(dibenzothiophen-4-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mDBtBPTzn), 2,4,6-tris[3'-(pyridine-3 -yl)biphenyl-3-yl]-1,3,5-triazine (abbreviation: TmPPPyTz), 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn), 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazin-2-yl]-11,12-dihydro-12-phenylindolo[2,3-a]carbazole (abbreviation: BP-Icz(II)Tzn), 2-[3'-(triphenylen-2-yl) Examples of organic compounds having a triazine skeleton include [biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mTpBPTzn), 3-[9-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]-9-phenyl-9H-carbazole (abbreviation: PCDBfTzn), and 2-(biphenyl-3-yl)-4-phenyl-6-{8-[(1,1':4',1''-terphenyl)-4-yl]-1-dibenzofuranyl}-1,3,5-triazine (abbreviation: mBP-TPDBfTzn).

[0264] Among the above, organic compounds having a phenanthroline ring, such as BPhen, BCP, NBPhen, and mPPhen2P, especially a 1,10-phenanthroline ring, are more preferred because the two nitrogen atoms contained therein can coordinate to metals, making them more likely to interact with metals. Also, organic compounds having a phenanthroline ring dimer structure, such as mPPhen2P, are more preferred because of their excellent stability.

[0265] The number of carbon atoms of the organic compound used for the second organic compound 161_2 is preferably 25 or more and 100 or less. By using such a number of carbon atoms, the organic compound can be made to have excellent sublimation properties, so that thermal decomposition of the organic compound can be suppressed during vacuum deposition, and good material utilization efficiency can be obtained. In addition, the glass transition temperature (T g ) of 100°C or more can be used. This makes it possible to make the intermediate layer a layer that is difficult to crystallize. Therefore, when processing a part of the organic compound layer by lithography, even if it is affected by oxygen or water in the atmosphere, or by chemical solutions or water during the process, it is possible to make the layer a layer that is difficult to crystallize. Therefore, it is possible to prevent the intermediate layer from crystallizing, which would cause an increase in the driving voltage or a decrease in the current efficiency of the light-emitting device. Therefore, T g By using an organic compound having a temperature of 100° C. or higher as the second organic compound 161_2, it can be suitably used as an intermediate layer of a light-emitting device in which a part of an organic compound layer is processed by lithography.

[0266] An organic compound having a phenanthroline ring and T g As an organic compound with a temperature of 100°C or higher, NBPhen (T g : 165℃), mPPhen2P(T g : 135 °C), 2,2'-(biphenyl-4,4'-diyl)bis(9-phenyl-1,10-phenanthroline) (abbreviation: PPhen2BP) (T g : 166 °C), 2,2'-biphenyl-3,3'-diylbis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2BP) (T g: 144 °C), 2,8-bis(phenanthroline-5-yl)dibenzofuran (abbreviation: 2,8Phen2DBf) (T g : 210℃), 5,5',5''-(benzene-1,3,5-triyl)tri-1,10-phenanthroline (abbreviation: Phen3P) (T g : 257℃), etc. g The value can be measured, for example, by using a differential scanning calorimeter (DSC8500, manufactured by PerkinElmer Japan Co., Ltd.) by placing the powder on an aluminum cell and raising the temperature at a rate of 40° C. / min.

[0267] The second organic compound 161_2 may have an acid dissociation constant pKa of 4 or more and less than 8. This reduces the hole transport property of the second organic compound 161_2, thereby reducing the hole transport property of the first layer 161a of the intermediate layer 160a and preventing holes from being transported from the first layer 161a to the second layer 162a. This is preferable because it results in an efficient light-emitting device. Furthermore, if the acid dissociation constant pKa is too high, the compound may become more soluble in water, resulting in poor resistance to water and chemicals used in lithography processes. Therefore, the acid dissociation constant pKa of the second organic compound 161_2 is preferably 4 or more and less than 8.

[0268] In a layer having a combination of the metal or metal compound 161_M, the first organic compound 161_1, and the second organic compound 161_2, the interaction between the materials occurs more efficiently than in a layer having only two of these materials (for example, a layer having the metal or metal compound 161_M and the first organic compound 161_1, or a layer having the metal or metal compound 161_M and the second organic compound 161_2). This can be confirmed by using an odd-numbered metal for the metal or metal compound 161_M and measuring the spin density of a film containing each material by electron spin resonance (ESR).

[0269] For example, if the spin density measured by ESR of a film containing a metal, the first organic compound 161_1, and the second organic compound 161_2 is higher than the spin density measured by ESR of a film containing a metal and the first organic compound 161_1 or the spin density measured by ESR of a film containing a metal and the second organic compound 161_2, it can be confirmed that the interaction between the materials occurs more efficiently in a layer having a combination of the metal, the first organic compound 161_1, and the second organic compound 161_2 compared to a layer having only two of these materials. Note that the measurement of the spin density by electron spin resonance is preferably performed at room temperature.

[0270] More specifically, for a film containing a metal and the first organic compound 161_1, the spin density due to a signal observed in the vicinity of a g value of 2.00 by electron spin resonance is 2×10 16 spins / cm 3 For a mixed film containing a metal and the second organic compound 161_2, the spin density due to a signal observed in the vicinity of a g value of 2.00 by electron spin resonance is 2 × 10 16 spins / cm 3 For a mixed film containing the first organic compound 161_1 and the second organic compound 161_2, the spin density due to a signal observed in the vicinity of a g value of 2.00 by electron spin resonance is 2×10 or less. 16 spins / cm 3 When the spin density of the mixed film containing the metal, the first organic compound 161_1, and the second organic compound 161_2 is less than 5×10 due to a signal observed in the vicinity of a g value of 2.00 by an electron spin resonance method, 16 spins / cm 3 More preferably, 1×10 17 spins / cm 3 In the above cases, it can be confirmed that in a layer having a combination of a metal, a first organic compound 161_1, and a second organic compound 161_2, interactions between the materials occur more efficiently than in a layer having only two of these materials.

[0271] The molar ratio of the metal to the total of the first organic compound 161_1 and the second organic compound 161_2 is preferably 0.1 to 10, more preferably 0.2 to 5, and even more preferably 0.5 to 2. Alternatively, the volume ratio is preferably 0.01 to 0.3, more preferably 0.02 to 0.2, and even more preferably 0.05 to 0.1. Mixing the metal, the first organic compound 161_1, and the second organic compound 161_2 at such a ratio can provide an intermediate layer with excellent electron injection properties. The volume ratio of the first organic compound 161_1 to the second organic compound 161_2 is preferably 0.1 to 10, more preferably 0.2 to 5, and even more preferably 0.5 to 2. By mixing the first organic compound 161_1 and the second organic compound 161_2 in such a ratio, an intermediate layer having a good electron transporting property can be provided.

[0272] The thickness of the first layer 161a of the intermediate layer 160a located on the anode side is preferably 3 nm to 20 nm, more preferably 5 nm to 10 nm, which allows the metal, the first organic compound 161_1, and the second organic compound 161_2 to function well as a composite material, thereby providing a light-emitting device with high luminous efficiency.

[0273] Next, the configuration of the second and third layers, which is preferable when the layer 200 is applied to the first layer of the intermediate layers, will be described.

[0274] [Second layer] The second layer of the intermediate layer is preferably a layer containing a third organic compound and a fourth organic compound, which is preferable because it allows for good hole injection into the upper light-emitting layer.

[0275] <Third organic compound> The third organic compound is preferably an organic compound having hole transport properties. As the organic compound having hole transport properties, various organic compounds such as aromatic amine compounds, heteroaromatic compounds, aromatic hydrocarbons, and polymer compounds (oligomers, dendrimers, polymers, etc.) can be used. Note that the organic compound having hole transport properties is preferably an organic compound having a molecular weight of 1×10 -6 cm 2 Preferably, the organic compound has a hole mobility of 1 / Vs or more. The organic compound having hole transport properties is preferably a compound having a fused aromatic hydrocarbon ring or a π-electron-rich heteroaromatic ring. As the fused aromatic hydrocarbon ring, an anthracene ring, a naphthalene ring, or the like is preferred. Furthermore, as the π-electron-rich heteroaromatic ring, a fused aromatic ring containing at least one of a pyrrole skeleton, a furan skeleton, and a thiophene skeleton in the ring is preferred, and specifically, a carbazole ring, a dibenzothiophene ring, or a ring in which an aromatic ring or a heteroaromatic ring is further fused to the above ring is preferred.

[0276] Such organic compounds having hole-transporting properties preferably have at least one of a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton. In particular, aromatic amines having a substituent containing a dibenzofuran ring or a dibenzothiophene ring, aromatic monoamines having a naphthalene ring, or aromatic monoamines in which a 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group may be used. It is preferable that these organic compounds having hole-transporting properties are substances having an N,N-bis(4-biphenyl)amino group, since this allows the fabrication of light-emitting devices with long lifetimes.

[0277] Specific examples of organic compounds having hole transport properties as described above include N-(4-biphenyl)-6,N-diphenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BnfABP), N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf), 4,4'-bis(6-phenylbenzo[b]naphtho[1,2-d]furan-8-yl)-4''-phenyltriphenylamine (abbreviation: BnfBB1BP), N,N-bis(4-biphenyl)benzylamine (abbreviation: BnfBB1BP), and N,N-bis(4-biphenyl)benzylamine (abbreviation: BnfBB1BP). N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-6-amine (abbreviation: BBABnf(6)), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf(8)), N,N-bis(4-biphenyl)benzo[b]naphtho[2,3-d]furan-4-amine (abbreviation: BBABnf(II)(4)), N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP), N-[4-(dibenzothiophen-4-yl)phenyl]-4-amino-p-terphenyl] ]-N-phenyl-4-biphenylamine (abbreviation: ThBA1BP), 4-(2-naphthyl)-4',4''-diphenyltriphenylamine (abbreviation: BBAβNB), 4-[4-(2-naphthyl)phenyl]-4',4''-diphenyltriphenylamine (abbreviation: BBAβNBi), 4,4'-diphenyl-4''-(6;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβNB), 4,4'-diphenyl-4''-(7;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβ NB-03), 4,4'-diphenyl-4''-(7-phenyl)naphthyl-2-yltriphenylamine (abbreviation: BBAPβNB-03), 4,4'-diphenyl-4''-(6;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B), 4,4'-diphenyl-4''-(7;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B-03), 4,4'-diphenyl-4''-(4;2'-binaphthyl-1-yl)triphenylamine (abbreviation: BBAβNαNB), 4,4'-Diphenyl-4''-(5;2'-binaphthyl-1-yl)triphenylamine (abbreviation: BBAβNαNB-02), 4-(4-biphenylyl)-4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: TPBiAβNB), 4-(3-biphenylyl)-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (abbreviation: mTPBiAβNBi), 4-(4-biphenylyl)-4'-[4-(2-naphthyl)phenyl] 4'-[4'-(3-phenyl-9H-carbazol-9-yl)biphenyl-4-yl]-4''-phenyltriphenylamine (abbreviated as TPBiAβNBi), 4-phenyl-4'-(1-naphthyl)triphenylamine (abbreviated as αNBA1BP), 4,4'-bis(1-naphthyl)triphenylamine (abbreviated as αNBB1BP), 4,4'-diphenyl-4''-[4'-(carbazol-9-yl)biphenyl-4-yl]triphenylamine (abbreviated as YGTBi1BP), 4'-[4-(3-phenyl-9H-carbazol-9-yl)furan N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-[4-(1-naphthyl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBNBSF), N,N- Bis(biphenyl-4-yl)-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: BBASF), N,N-bis(biphenyl-4-yl)-9,9'-spirobi[9H-fluorene]-4-amine (abbreviation: BBASF(4)), N-(biphenyl-2-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi[9H-fluorene]-4-amine (abbreviation: oFBiSF), N-(biphenyl-4-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)dibenzofuran-4-amine (abbreviation: FrBiF), N-[4-(1-naphthyl)phenyl]-N-[3-(6-phenyldibenzofuran-4-yl)phenyl]-1-naphthylamine (abbreviation: mPDBfBNBN), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-phenyl-4' -[4-(9-phenylfluoren-9-yl)phenyl]triphenylamine (abbreviation: BPAFLBi), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'- Di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluoren]-2-amine (abbreviation: PCBASF), N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), N,N-bis( Examples of such amines include N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-4-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-3-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-2-amine, and N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-1-amine.

[0278] In addition, 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), 4,4'-bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviation: DNTPD), and 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B) can also be used as materials having hole transport properties.

[0279] <The fourth organic compound> The fourth organic compound is preferably a material that has acceptor properties for the third organic compound. As the acceptor substance, an organic compound having an electron-withdrawing group (such as a halogen group or a cyano group) is preferably used, and an organic compound having four or more halogen groups or cyano groups is more preferably used. Specific examples include 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT-CN), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviation: F6-TCNNQ), 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyren-2-ylidene)malononitrile, etc. In particular, compounds in which an electron-withdrawing group is bonded to a fused aromatic ring having multiple heteroatoms, such as HAT-CN, are thermally stable and preferred. Radialene derivatives containing electron-withdrawing groups (especially halogen groups such as fluoro groups, cyano groups, etc.) are also preferred because of their extremely high electron-accepting properties. Specific examples include α,α',α''-1,2,3-cyclopropanetriylidenetris[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α',α''-1,2,3-cyclopropanetriylidenetris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], and α,α',α''-1,2,3-cyclopropanetriylidenetris[2,3,4,5,6-pentafluorobenzeneacetonitrile]. In addition to the organic compounds mentioned above, other materials that can be used as electron-accepting materials include transition metal oxides such as molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, and manganese oxide.

[0280] The second layer preferably exhibits a signal observed by electron spin resonance. For example, the spin density resulting from a signal observed around a g value of 2.00 is 1×10 17 spins / cm 3 More than 1×10 is preferable. 18spins / cm 3 More than 1×10 is preferable. 19 spins / cm 3 The above is even more preferable. This allows the second layer to function as a charge generation layer. Also, a light-emitting device with low driving voltage and high efficiency can be fabricated.

[0281] [Third Layer] A third layer may be provided between the first and second layers of the intermediate layer to facilitate the transfer of electrons between these two layers.

[0282] The third layer contains a substance having electron-transporting properties and has a function of preventing interaction between the first layer and the second layer and smoothly transferring electrons. The LUMO level of the substance having electron-transporting properties contained in the third layer 163 is preferably between the LUMO level of the acceptor substance in the second layer 162 and the LUMO level of the organic compound contained in the layer in contact with the intermediate layer 160 in the light-emitting unit on the first electrode 101 side. The specific energy level of the LUMO level of the substance having electron-transporting properties used in the third layer 163 is −5.0 eV or higher, preferably −5.0 eV or higher to −3.0 eV or lower, more preferably −4.30 eV or higher to −3.00 eV or lower, and more preferably −4.30 eV or higher to −3.30 eV or lower, which makes it easy to inject electrons generated in the second layer into the first layer, and therefore is preferable in that an increase in the driving voltage of the light-emitting device can be suppressed. Note that as the substance having an electron transporting property used for the third layer 163, a phthalocyanine-based material or a metal complex having a metal-oxygen bond and an aromatic ligand is preferably used.

[0283] Specifically, perylene tetracarboxylic acid derivatives such as diquinoxalino[2,3-a:2',3'-c]phenazine (abbreviation: HATNA), 2,3,8,9,14,15-hexafluorodiquinoxalino[2,3-a:2',3'-c]phenazine (abbreviation: HATNA-F6), 3,4,9,10-perylene tetracarboxylic acid diimide (abbreviation: PTCDI), and 3,4,9,10-perylene tetracarboxylic-bis-benzimidazole (abbreviation: PTCBI), (C60-Ih)[5,6]fullerene (abbreviation: C60), (C70-D5h)[5,6]fullerene (abbreviation: C70), and phthalocyanine (abbreviation: HPc) can be used. Metal phthalocyanines containing copper, zinc, cobalt, iron, chromium, nickel, etc., such as copper phthalocyanine (abbreviated as CuPc), zinc phthalocyanine (abbreviated as ZnPc), cobalt phthalocyanine (abbreviated as CoPc), iron phthalocyanine (abbreviated as FePc), tin phthalocyanine (abbreviated as SnPc), tin oxide phthalocyanine (abbreviated as SnOPc), titanium oxide phthalocyanine (abbreviated as TiOPc), and vanadium oxide phthalocyanine (abbreviated as VOPc), and their derivatives can also be used. Phthalocyanine-based metal complexes, such as copper phthalocyanine or zinc phthalocyanine, or 2,3,8,9,14,15-hexafluorodiquinoxalino[2,3-a:2',3'-c]phenazine are particularly preferred.

[0284] The thickness of the third layer 163 is preferably 1 nm or more and 10 nm or less, and more preferably 2 nm or more and 5 nm or less.

[0285] The structure described in this embodiment mode can be used in appropriate combination with structures described in other embodiments.

[0286] (Embodiment 2) In this embodiment, other structures of the light-emitting device of one embodiment of the present invention will be described.

[0287] 8A illustrates a light-emitting device 130, which is an example of a light-emitting device according to one embodiment of the present invention. The light-emitting device 130 includes an organic compound layer 103 including a light-emitting layer 113 between a first electrode 101 including an anode and a second electrode 102 including a cathode.

[0288] 8B illustrates a light-emitting device 130, which is another example of a light-emitting device of one embodiment of the present invention. The light-emitting device 130 is a tandem light-emitting device. The light-emitting device 130 includes, as the organic compound layer 103, a first light-emitting unit 501 including a first light-emitting layer 113_1, a second light-emitting unit 502 including a second light-emitting layer 113_2, and an intermediate layer 160. The intermediate layer 160 includes a first layer 161, a second layer 162, and a third layer 163 between the first layer 161 and the second layer 162.

[0289] In this embodiment, an example of a light-emitting device having one intermediate layer 160 and two light-emitting units is described, but the light-emitting device may also have n (n is an integer greater than or equal to 1) intermediate layers and n+1 light-emitting units.

[0290] For example, the light-emitting device 130 shown in FIG. 8(C) is an example of a tandem light-emitting device in which n is 2 and the organic compound layer 103 includes a first light-emitting unit 501, a first intermediate layer 160_1, a second light-emitting unit 502, a second intermediate layer 160_2, and a third light-emitting layer 113_3. The color gamuts of the light emitted by the light-emitting layers in each light-emitting unit may be the same or different. The light-emitting layers may have a single layer or a multilayer structure. For example, white light can be obtained by configuring the first and third light-emitting units to emit light in the blue region, and the second light-emitting unit to emit light in the red and green regions from the multilayer light-emitting layer.

[0291] 8(D) is an example of a tandem light-emitting device having a fourth light-emitting unit 504 including a first light-emitting unit 501, a first intermediate layer 160_1, a second light-emitting unit 502, a second intermediate layer 160_2, a third light-emitting unit 503, a third intermediate layer 160_3, and a fourth light-emitting layer 113_4 as the organic compound layer 103. The color gamuts of the light emitted by the light-emitting layers in each light-emitting unit may be the same or different. The light-emitting layer may have a single layer or a multilayer structure. For example, the four light-emitting units may have a configuration in which three of the four light-emitting units are blue (B) and one is green (G), a configuration in which two of the four light-emitting units are blue (B) and two are yellow (Y), or a configuration in which one of the four light-emitting units is red (R), one is green (G), and two are blue (B).

[0292] The light-emitting device 130 may be, for example, a light-emitting device fabricated using a lithography method. In the case of a light-emitting device fabricated using a lithography method, at least the light-emitting layer 113 or the second light-emitting layer 113_2 and the organic compound layer closer to the first electrode 101 than the light-emitting layer 113 are processed simultaneously, and therefore, their edges are roughly aligned in the vertical direction.

[0293] The organic compound layer 103 may include other functional layers in addition to the light-emitting layer. Fig. 8A illustrates a configuration in which the organic compound layer 103 includes a hole injection layer 111, a hole transport layer 112, an electron transport layer 114, and an electron injection layer 115 in addition to the light-emitting layer 113. The first light-emitting unit 501 and the second light-emitting unit 502 may include other functional layers in addition to the light-emitting layer. Fig. 8B illustrates a configuration in which the first light-emitting unit 501 includes a hole injection layer 111, a first hole transport layer 112_1, and a first electron transport layer 114_1 in addition to the first light-emitting layer 113_1, and the second light-emitting unit 502 includes a second hole transport layer 112_2, a second electron transport layer 114_2, and an electron injection layer 115 in addition to the second light-emitting layer 113_2. However, the configuration of the organic compound layer 103 in the present invention is not limited to this, and any of the layers may be omitted, or other layers may be provided. Representative examples of such other layers include a carrier blocking layer (hole blocking layer, electron blocking layer), an exciton blocking layer, etc.

[0294] Next, the configuration of the light-emitting device 130 other than the intermediate layer 160 will be described.

[0295] <Configuration of the first electrode> The first electrode 101 is an electrode including an anode. The first electrode 101 may have a stacked structure, in which case the layer in contact with the organic compound layer 103 functions as the anode. The anode is preferably formed using a metal, alloy, conductive compound, or mixture thereof having a large work function (specifically, 4.0 eV or more). Specific examples include indium tin oxide (ITO), indium tin oxide containing silicon or silicon oxide, indium zinc oxide, and indium oxide containing tungsten oxide and zinc oxide (IWZO). These conductive metal oxide films are usually formed by sputtering, but may also be formed by applying a sol-gel method or the like. For example, indium zinc oxide may be formed by sputtering using a target in which 1 to 20 wt % of zinc oxide is added to indium oxide. Indium oxide containing tungsten oxide and zinc oxide (IWZO) can also be formed by sputtering using a target containing 0.5 to 5 wt % tungsten oxide and 0.1 to 1 wt % zinc oxide relative to indium oxide. Other materials that can be used for the anode include gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), and nitrides of metal materials (e.g., titanium nitride). Graphene can also be used for the anode. Using the second layer 162 of the intermediate layer 160 as a layer in contact with the anode (typically a hole injection layer) allows the electrode material to be selected regardless of the work function.

[0296] <<Configuration of Hole Injection Layer>> The hole injection layer 111 is provided in contact with the anode and has the function of facilitating injection of holes into the organic compound layer 103 (first light-emitting unit 501). The hole injection layer 111 can be formed of a phthalocyanine compound such as phthalocyanine (abbreviation: HPc) or copper phthalocyanine (abbreviation: CuPc), an aromatic amine compound such as 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB) or 4,4'-bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviation: DNTPD), or a polymer such as poly(3,4-ethylenedioxythiophene) / (polystyrenesulfonic acid) (abbreviation: PEDOT / PSS).

[0297] The hole-injection layer 111 may be formed using a substance having electron acceptor properties. As the substance having electron acceptor properties, the substances exemplified as acceptor substances used for the second layer 162 in the intermediate layer 160 can be used.

[0298] The hole injection layer 111 may be formed using the hole transporting material used for the second layer 162 in the intermediate layer 160 described above.

[0299] In the hole-injection layer 111, the organic compound having hole-transporting properties used in the composite material is preferably a substance having a relatively low HOMO level, that is, a HOMO level of −5.7 eV or more and −5.4 eV or less. When the organic compound having hole-transporting properties used in the composite material has a relatively low HOMO level, holes can be easily injected into the hole-transport layer, and a light-emitting device with a long lifetime can be easily obtained. Furthermore, when the organic compound having hole-transporting properties used in the composite material has a relatively low HOMO level, hole induction can be appropriately suppressed, resulting in a light-emitting device with a long lifetime.

[0300] By forming the hole injection layer 111, the hole injection property becomes good, and a light emitting device with a low driving voltage can be obtained.

[0301] Among substances having acceptor properties, organic compounds having acceptor properties are easy to use because they can be easily vapor-deposited and formed into a film.

[0302] Furthermore, since the second layer 162 in the intermediate layer 160 functions as a hole injection layer, the second light-emitting unit 502 does not have a hole injection layer, but the second light-emitting unit 502 may have a hole injection layer.

[0303] <<Configuration of Hole Transport Layer>> The hole transport layers (the first hole transport layer 112_1 and the second hole transport layer 112_2) are formed by containing an organic compound having a hole transport property. -6 cm 2 It is preferable that the hole mobility is / Vs or more.

[0304] Examples of the material having 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), 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-methylphenyl-4,4'-diaminobiphenyl (abbreviation: 4,4'-bis(9H-fluoren-2-yl)triphenylamine) ... '-(9-Phenylfluoren-9-yl)triphenylamine (abbreviated as mBPAFLP), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl) Compounds with an aromatic amine skeleton, such as 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), and N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF), 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di( N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), 9,9'-bis(biphenyl-4-yl)-3,3'-bi-9H-carbazole (abbreviation: BisBPCz), 9,9'-bis(biphenyl-3-yl)-3,3'-bi-9H-carbazole (abbreviation: BismBPCz), 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-(2-naphthyl)-9'-[1,1':4',1"-terf phenyl]-3-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3',1"-terphenyl]-3-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3',1"-terphenyl]-5'-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':4',1"-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3',1"-terphenyl]-4-yl-3,3 '-9H,9'H-Bicarbazole, 9-(2-naphthyl)-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole, 9-phenyl-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole (abbreviation: PCCzTp), 9,9'-bis(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(4-biphenyl)-9'-(triphenylen-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(triphenylen-2-yl)-9'-[1,1':3',1"-taphe compounds having a carbazole skeleton such as [4-yl-3,3'-9H,9'H-bicarbazole]; compounds having a thiophene skeleton such as 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), and 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV);Examples of the compounds include compounds having a furan skeleton, such as 4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II). Among the compounds mentioned above, compounds having an aromatic amine skeleton and compounds having a carbazole skeleton are preferred because they have good reliability, high hole transport properties, and contribute to reducing driving voltage. Note that the substances listed as materials having hole transport properties used in the composite material of the hole injection layer 111 can also be suitably used as materials constituting the hole transport layer.

[0305] <<Configuration of the light-emitting layer>> The light-emitting layers (light-emitting layer 113, first light-emitting layer 113_1, second light-emitting layer 113_2) preferably contain a light-emitting substance and a host material. The light-emitting layer may also contain other materials. Alternatively, the light-emitting layer may be a laminate of two layers with different compositions.

[0306] The light-emitting material may be a fluorescent material, a phosphorescent material, a material that exhibits thermally activated delayed fluorescence (TADF), or any other light-emitting material.

[0307] Examples of materials that can be used as fluorescent materials in the light-emitting layer include the following: In addition, fluorescent materials other than these can also be used.

[0308] 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine (abbreviation: PAP2BPy), 5,6-bis[4'-(10-phenyl-9-anthryl)biphenyl-4-yl]-2,2'-bipyridine (abbreviation: PAPP2BPy), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine )phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn), N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-diphenyl-N-[4-( 10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetra-tert-butylperylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), N,N''-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene)bis(N,N',N'-triphenyl-1,4-phenylenediamine) (abbreviation: DPABPA), N,9 -diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine (abbreviated as 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviated as 2DPAPPA), N,N,N',N',N'',N'',N''',N'''-octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviated as 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-1,4-phenylenediamine (abbreviation: 2DPAPA), 9,10-bis(2-biphenyl)-2-(N,N',N'-triphenyl-1,4-phenylenediamine-N-yl)anthracene (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: DPQd), rubrene, 5,12-bis(biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyra N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviation: p-mPhTD), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-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-mPhTD), Name: 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),6-Bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDCM), 2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJTM), N,N'-diphenyl-N,N'-(1,6-pyren-diyl)bis[(6-phenylbenzo[b]naphtho]] Examples include N,N'-diphenyl-N,N'-bis(9-phenyl-9H-carbazol-2-yl)naphtho[2,3-b;6,7-b']bisbenzofuran-3,10-diamine (abbreviated as 3,10PCA2Nbf(IV)-02), and 3,10-bis[N-(dibenzofuran-3-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviated as 3,10FrA2Nbf(IV)-02). In particular, condensed aromatic diamine compounds, such as pyrenediamine compounds 1,6FLPAPrn, 1,6mMemFLPAPrn, and 1,6BnfAPrn-03, are preferred due to their high hole-trapping properties and excellent luminous efficiency and reliability.

[0309] When a phosphorescent material is used as the light-emitting material in the light-emitting layer, examples of materials that can be used include the following.

[0310] Organometallic iridium complexes with a 4H-triazole skeleton, such as tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN2]phenyl-κC}iridium(III) (abbreviation: [Ir(mpptz-dmp)3]), tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Mptz)3]), tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(iPrptz-3b)3]), and tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III) Organometallic iridium complexes with a 1H-triazole skeleton, such as tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Prptz1-Me)3]), 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 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’] Organometallic iridium complexes with phenylpyridine derivatives bearing electron-withdrawing groups as ligands, such as iridium(III) acetylacetonate (abbreviated as FIracac), are compounds that exhibit blue phosphorescence and have an emission peak in the wavelength range from 450 nm to 520 nm.

[0311] Also, tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)3]), tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)3]), (acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)2(acac)]), (acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)2(acac)]), (acetylacetonato)bis[6-(2-norbornyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(nbppm)2(acac)]), (acetylacetonato)bis[5-methyl-6- Organometallic iridium complexes with a pyrimidine skeleton, such as (2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(mpmppm)2(acac)]) and (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm)2(acac)]), organometallic iridium complexes with a pyrazine skeleton, such as (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-Me)2(acac)]) and (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-iPr)2(acac)]), and 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)]), [2-d3-methyl-8-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN2)phenyl-κC]iridium(III) (abbreviation: Ir(5mppy-d3)2(mbfpypy-d3)), {2-(methyl-d3)-8-[4-(1-methylethyl-1-d)-2-pyridinyl-κN]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(mbfpy These include organometallic iridium complexes with a pyridine skeleton, such as [2-d3-methyl-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviated as Ir(ppy)2(mbfpypy-d3)), [2-(4-methyl-5-phenyl-2-pyridinyl-κN)phenyl-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviated as Ir(ppy)2(mdppy)), and rare earth metal complexes, such as tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviated as [Tb(acac)3(Phen)]). These compounds mainly exhibit green phosphorescence, with an emission peak in the wavelength range of 500 to 600 nm. Organometallic iridium complexes having a pyrimidine skeleton are particularly preferred because they are remarkably superior in reliability and luminous efficiency.

[0312] and organometallic iridium complexes having a pyrimidine skeleton, such as (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III) (abbreviation: [Ir(5mdppm)2(dibm)]), bis[4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(5mdppm)2(dpm)]), and bis[4,6-di(naphthalen-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(d1npm)2(dpm)]). Organometallic iridium complexes with a pyrazine skeleton, such as (acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: [Ir(tppr)2(acac)]), bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: [Ir(tppr)2(dpm)]), and (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: [Ir(Fdpq)2(acac)]), tris(1-phenylisoquinolinato-N,C 2’ ) Iridium(III) (abbreviation: [Ir(piq)3]), bis(1-phenylisoquinolinato-N,C 2’ Examples include organometallic iridium complexes with a pyridine skeleton, such as iridium(III) acetylacetonate (abbreviated as [Ir(piq)2(acac)]), platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrinplatinum(II) (abbreviated as PtOEP), and rare earth metal complexes such as tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III) (abbreviated as [Eu(DBM)3(Phen)]) and tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III) (abbreviated as [Eu(TTA)3(Phen)]). These compounds exhibit red phosphorescence, with peak emission in the wavelength range of 600 to 700 nm. Furthermore, organometallic iridium complexes having a pyrazine skeleton can emit red light with good chromaticity.

[0313] In addition to the phosphorescent compounds described above, known phosphorescent compounds may be selected and used.

[0314] TADF materials include fullerene and its derivatives, acridine and its derivatives, eosin derivatives, etc. Also available are metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd). Examples of the metal-containing porphyrin include protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF2(OEP)), etioporphyrin-tin fluoride complex (SnF2(Etio I)), and octaethylporphyrin-platinum chloride complex (PtCl2OEP), all of which are shown in the following structural formulas.

[0315] [ka]

[0316] In addition, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 9-(4,6-diphenyl-1,3,5-triazin-2-yl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCzTzn), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 2-[4-(10H-phenoxazin-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), and Heterocyclic compounds having one or both of a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring, such as 3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), and 10-phenyl-10H,10'H-spiro[acridin-9,9'-anthracene]-10'-one (abbreviation: ACRSA), can also be used. The heterocyclic compound has a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring, and therefore has high electron transport and hole transport properties, and is therefore preferred. Among the skeletons having a π-electron-deficient heteroaromatic ring, pyridine skeleton, diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), and triazine skeleton are preferred because they are stable and reliable. In particular, benzofuropyrimidine skeleton, benzothienopyrimidine skeleton, benzofuropyrazine skeleton, and benzothienopyrazine skeleton are preferred because they have high acceptor properties and good reliability. Furthermore, among the skeletons having a π-electron-rich heteroaromatic ring, acridine skeleton, phenoxazine skeleton, phenothiazine skeleton, furan skeleton, thiophene skeleton, and pyrrole skeleton are preferred because they are stable and reliable.The furan skeleton is preferably a dibenzofuran skeleton, and the thiophene skeleton is preferably a dibenzothiophene skeleton. The pyrrole skeleton is particularly preferably an indole skeleton, a carbazole skeleton, an indolocarbazole skeleton, a bicarbazole skeleton, or a 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole skeleton. Substances in which a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded are particularly preferred because the electron-donating ability of the π-electron-rich heteroaromatic ring and the electron-accepting ability of the π-electron-deficient heteroaromatic ring are both enhanced, thereby reducing the energy difference between the S1 level and the T1 level, thereby enabling efficient thermally activated delayed fluorescence. Instead of the π-electron-deficient heteroaromatic ring, an aromatic ring bonded to an electron-withdrawing group such as a cyano group may be used. The π-electron-rich skeleton may be, for example, an aromatic amine skeleton or a phenazine skeleton. Examples of usable π-electron-deficient skeletons include a xanthene skeleton, a thioxanthene dioxide skeleton, an oxadiazole skeleton, a triazole skeleton, an imidazole skeleton, an anthraquinone skeleton, a boron-containing skeleton such as phenylborane or boranthrene, an aromatic ring having a nitrile group or a cyano group such as benzonitrile or cyanobenzene, a heteroaromatic ring, a carbonyl skeleton such as benzophenone, a phosphine oxide skeleton, a sulfone skeleton, etc. In this way, a π-electron-deficient skeleton and a π-electron-rich skeleton can be used in place of at least one of a π-electron-deficient heteroaromatic ring and a π-electron-rich heteroaromatic ring.

[0317] [ka]

[0318] In addition, TADF materials that are in thermal equilibrium between the singlet excited state and the triplet excited state may also be used. Such TADF materials have a shorter emission lifetime (excitation lifetime), which can suppress efficiency decline in the high brightness range of light-emitting devices. Specific examples include materials with the molecular structure shown below.

[0319] [ka]

[0320] TADF materials are materials with a small difference between the S1 and T1 levels, and have the ability to convert triplet excitation energy to singlet excitation energy through reverse intersystem crossing. Therefore, triplet excitation energy can be upconverted to singlet excitation energy (reverse intersystem crossing) using a small amount of thermal energy, allowing for efficient generation of a singlet excited state. Triplet excitation energy can also be converted into light emission.

[0321] Furthermore, exciplexes (also known as exciplexes), which form an excited state with two types of substances, have an extremely small difference between the S1 and T1 levels and function as TADF materials that can convert triplet excitation energy into singlet excitation energy.

[0322] The phosphorescence spectrum observed at low temperatures (for example, 77 K to 10 K) can be used as an indicator of the T1 level. For a TADF material, when a tangent line is drawn at the base of the fluorescence spectrum on the short wavelength side and the energy of the wavelength of the extrapolated line is defined as the S1 level, and a tangent line is drawn at the base of the phosphorescence spectrum on the short wavelength side and the energy of the wavelength of the extrapolated line is defined as the T1 level, the difference between S1 and T1 is preferably 0.3 eV or less, and more preferably 0.2 eV or less.

[0323] When a TADF material is used as a light-emitting material, the S1 level of the host material is preferably higher than the S1 level of the TADF material, and the T1 level of the host material is preferably higher than the T1 level of the TADF material.

[0324] As the host material of the light-emitting layer, various carrier transport materials such as a material having an electron transport property and / or a material having a hole transport property, and the above-mentioned TADF material can be used.

[0325] As the material having a hole transporting property, the materials exemplified above as the material having a hole transporting property can be used in the same manner.

[0326] As the material having an electron transporting property, the materials exemplified above as the material having an electron transporting property can be used in the same manner.

[0327] The TADF materials that can be used as host materials are the same as those listed above. When a TADF material is used as a host material, the triplet excitation energy generated in the TADF material is converted to singlet excitation energy through reverse intersystem crossing, and the energy is then transferred to the light-emitting material, thereby improving the luminous efficiency of the light-emitting device. In this case, the TADF material functions as an energy donor, and the light-emitting material functions as an energy acceptor.

[0328] This is very effective when the luminescent material is a fluorescent luminescent material. In this case, in order to obtain high luminous efficiency, the S1 level of the TADF material is preferably higher than the S1 level of the fluorescent luminescent material. In addition, the T1 level of the TADF material is preferably higher than the S1 level of the fluorescent luminescent material. Therefore, the T1 level of the TADF material is preferably higher than the T1 level of the fluorescent luminescent material.

[0329] It is also preferable to use a TADF material that emits light that overlaps with the wavelength of the lowest-energy absorption band of the fluorescent material, as this allows for smooth transfer of excitation energy from the TADF material to the fluorescent material, resulting in efficient light emission.

[0330] Furthermore, to efficiently generate singlet excitation energy from triplet excitation energy through reverse intersystem crossing, carrier recombination is preferred in the TADF material. Furthermore, it is preferable that the triplet excitation energy generated in the TADF material does not transfer to triplet excitation energy in the fluorescent material. To achieve this, the fluorescent material preferably has a protecting group around the luminophore (the skeleton responsible for light emission) of the fluorescent material. The protecting group is preferably a substituent without a π bond, and is preferably a saturated hydrocarbon. Specific examples include alkyl groups with 3 to 10 carbon atoms, substituted or unsubstituted cycloalkyl groups with 3 to 10 carbon atoms, and trialkylsilyl groups with 3 to 10 carbon atoms. Multiple protecting groups are even more preferred. Substituents without a π bond have poor carrier transport properties, allowing for increased distance between the TADF material and the luminophore of the fluorescent material without significantly affecting carrier transport or carrier recombination. Here, the term "luminophore" refers to the atomic group (skeleton) responsible for light emission in the fluorescent material. The luminophore preferably has a skeleton having a π bond, preferably contains an aromatic ring, and preferably has a fused aromatic ring or a fused heteroaromatic ring. Examples of such luminophores include a phenanthrene skeleton, a stilbene skeleton, an acridone skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a naphthalene skeleton, an anthracene skeleton, a fluorene skeleton, a chrysene skeleton, a triphenylene skeleton, a tetracene skeleton, a pyrene skeleton, a perylene skeleton, a coumarin skeleton, a quinacridone skeleton, and a naphthobisbenzofuran skeleton. In particular, fluorescent materials having a naphthalene skeleton, an anthracene skeleton, a fluorene skeleton, a chrysene skeleton, a triphenylene skeleton, a tetracene skeleton, a pyrene skeleton, a perylene skeleton, a coumarin skeleton, a quinacridone skeleton, or a naphthobisbenzofuran skeleton are preferred because of their high fluorescence quantum yield.

[0331] When a fluorescent emitting substance is used as the emitting substance, a material having an anthracene skeleton is suitable as the host material. Using a substance having an anthracene skeleton as a host material for a fluorescent emitting substance makes it possible to realize an emitting layer with both excellent luminous efficiency and durability. Substances having an anthracene skeleton used as a host material are preferably those having a diphenylanthracene skeleton, particularly a 9,10-diphenylanthracene skeleton, due to their chemical stability. Furthermore, host materials having a carbazole skeleton are preferred because of their enhanced hole injection and transport properties. However, host materials containing a benzocarbazole skeleton, in which a benzene ring is further condensed to the carbazole skeleton, are even more preferred because their HOMO is approximately 0.1 eV higher than that of host materials having a carbazole skeleton, facilitating hole insertion. In particular, host materials containing a dibenzocarbazole skeleton are preferred because their HOMO is approximately 0.1 eV higher than that of host materials having a carbazole skeleton, facilitating hole insertion, and also exhibiting excellent hole transport properties and high heat resistance. Therefore, a more preferable host material is a substance having both a 9,10-diphenylanthracene skeleton and a carbazole skeleton (or a benzocarbazole skeleton or a dibenzocarbazole skeleton). Note that, from the viewpoint of the hole injection / transport property, a benzofluorene skeleton or a dibenzofluorene skeleton may be used instead of the carbazole skeleton.Examples of such substances include 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), 3-[4-(1-naphthyl)phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: CzPA), 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA), 6-[3-(9,10-diphenyl-2-anthryl)phenyl]benzo[b]naphtho[1,2-d]furan (abbreviation: 2mBnfPPA), 9-phenyl-10-[4'-(9-phenyl-9H-fluoren-9-yl)biphenyl-4-yl] 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: αN-βNPAnth), 9-(1-naphthyl)-10-(2-naphthyl)anthracene (abbreviation: α,β-ADN), 2-(10-phenylanthracen-9-yl)dibenzofuran, 2-(10-phenyl-9-anthracenyl)benzo Examples include zo[b]naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA), 9-(2-naphthyl)-10-[3-(2-naphthyl)phenyl]anthracene (abbreviation: βN-mβNPAnth), 1-{4-[10-(biphenyl-4-yl)-9-anthracenyl]phenyl}-2-ethyl-1H-benzimidazole (abbreviation: EtBImPBPhA), etc. In particular, CzPA, cgDBCzPA, 2mBnfPPA, and PCzPA are preferred choices because they exhibit very good properties.

[0332] The host material may be a mixture of multiple substances, and when a mixture of host materials is used, it is preferable to mix a material having electron-transporting properties with a material having hole-transporting properties. By mixing a material having electron-transporting properties with a material having hole-transporting properties, the transport properties of the light-emitting layer 113 can be easily adjusted, and the recombination region can also be easily controlled. The weight ratio of the content of the material having hole-transporting properties to the material having electron-transporting properties may be 1:19 to 19:1 (material having hole-transporting properties:material having electron-transporting properties).

[0333] A phosphorescent material can be used as part of the mixed material. The phosphorescent material can be used as an energy donor that provides excitation energy to a fluorescent material when the fluorescent material is used as a light-emitting material.

[0334] Furthermore, these mixed materials may form an exciplex. It is preferable to select a combination that forms an exciplex that emits light that overlaps with the wavelength of the lowest-energy absorption band of the light-emitting material, because this allows for smooth energy transfer and efficient light emission. Furthermore, using this structure is also preferable because it reduces the driving voltage.

[0335] At least one of the materials forming the exciplex may be a phosphorescent material, which allows efficient conversion of triplet excitation energy into singlet excitation energy through reverse intersystem crossing.

[0336] As a combination of materials that efficiently form an exciplex, it is preferable that the HOMO level of the hole-transporting material is equal to or higher than the HOMO level of the electron-transporting material. It is also preferable that the LUMO level of the hole-transporting material is equal to or higher than the LUMO level of the electron-transporting material. The LUMO and HOMO levels of the materials can be derived from the electrochemical properties (reduction potential and oxidation potential) of the materials measured by cyclic voltammetry (CV).

[0337] The formation of exciplexes can be confirmed by, for example, comparing the emission spectra of a hole-transporting material, an electron-transporting material, and a mixed film of these materials and observing the phenomenon that the emission spectrum of the mixed film is shifted to longer wavelengths than the emission spectra of each material (or has a new peak at longer wavelengths). Alternatively, it can be confirmed by comparing the transient photoluminescence (PL) of a hole-transporting material, the transient PL of an electron-transporting material, and a mixed film of these materials and observing differences in transient response, such as the transient PL lifetime of the mixed film having a longer-lived component or a larger proportion of delayed components than the transient PL lifetimes of the individual materials. The above-mentioned transient PL can also be interpreted as transient electroluminescence (EL). In other words, the formation of exciplexes can also be confirmed by comparing the transient EL of a hole-transporting material, the transient EL of an electron-transporting material, and a mixed film of these materials and observing differences in transient response.

[0338] <Configuration of Electron Transport Layer> The electron transport layer (the electron transport layer 114, the first electron transport layer 114_1, and the second electron transport layer 114_2) is a layer containing a substance having an electron transport property. The material having an electron transport property is a material having an electron mobility of 1×10 at a square root of an electric field strength [V / cm] of 600. -7 cm 2 / Vs or more, preferably 1×10 -6 cm 2 A substance having an electron mobility of 1 / Vs or more is preferred. Note that other substances can be used as long as they have a higher electron transporting property than holes. Note that the organic compound is preferably an organic compound having a π-electron-deficient heteroaromatic ring. The organic compound having a π-electron-deficient heteroaromatic ring is preferably one or more of, for example, an organic compound having a heteroaromatic ring with an azole skeleton, an organic compound having a heteroaromatic ring with a pyridine skeleton, an organic compound having a heteroaromatic ring with a diazine skeleton, and an organic compound having a heteroaromatic ring with a triazine skeleton.

[0339] The organic compounds having electron transport properties that can be used in the electron transport layer can be the same as those that can be used as the organic compounds having electron transport properties in the first layer of the intermediate layer 160. Among them, organic compounds containing a heteroaromatic ring with a diazine skeleton, organic compounds containing a heteroaromatic ring with a pyridine skeleton, and organic compounds containing a heteroaromatic ring with a triazine skeleton are preferred because of their high reliability. In particular, organic compounds containing a heteroaromatic ring with a diazine (pyrimidine or pyrazine) skeleton and organic compounds containing a heteroaromatic ring with a triazine skeleton have high electron transport properties and contribute to reducing driving voltage.

[0340] In addition, the electron transport layer has an electron mobility of 1×10 when the square root of the electric field strength [V / cm] is 600. -7 cm 2 / Vs or more 5×10 -5 cm 2 / Vs or less. By reducing the electron transport property of the electron transport layer, the amount of electrons injected into the light-emitting layer can be controlled, and the light-emitting layer can be prevented from becoming electron-excessive. This configuration is particularly preferable because it improves the lifetime when the hole injection layer is formed of a composite material and the HOMO level of the material having hole transport property in the composite material is a substance having a relatively low HOMO level of -5.7 eV or more and -5.4 eV or less. In this case, the HOMO level of the material having electron transport property is preferably -6.0 eV or more.

[0341] For example, heteroaromatic compounds can be used as electron transport materials for the electron transport layer. A heteroaromatic compound is a cyclic compound containing at least two different elements in a ring. Examples of ring structures include three-, four-, five-, and six-membered rings, with five- or six-membered rings being particularly preferred. Preferred heteroaromatic compounds contain one or more elements, such as nitrogen, oxygen, or sulfur, in addition to carbon. Heteroaromatic compounds containing nitrogen (nitrogen-containing heteroaromatic compounds) are particularly preferred, and it is preferable to use materials with high electron transport properties (electron transport materials), such as nitrogen-containing heteroaromatic compounds or π-electron-deficient heteroaromatic compounds containing the same. The compound of embodiment 1 has electron transport properties and can therefore be used as an electron transport material.

[0342] The electron transport material may be a material different from the material used in the light-emitting layer. Not all of the excitons generated by carrier recombination in the light-emitting layer can contribute to light emission, and they may diffuse to layers adjacent to or located nearby the light-emitting layer. To avoid this phenomenon, it is preferable that the energy level (lowest singlet excitation level or lowest triplet excitation level) of the material used in the layer adjacent to or located nearby the light-emitting layer is higher than that of the material used in the light-emitting layer. Therefore, by using an electron transport material different from the material used in the light-emitting layer, a highly efficient device can be obtained.

[0343] A heteroaromatic compound is an organic compound that contains at least one heteroaromatic ring.

[0344] The heteroaromatic ring has any one of a pyridine ring, a diazine ring, a triazine ring, an azole ring, an oxazole ring, and a thiazole ring. The heteroaromatic ring having a diazine ring includes a heteroaromatic ring having a pyrimidine ring, a pyrazine ring, a pyridazine ring, and the like. The heteroaromatic ring having an azole ring includes a heteroaromatic ring having an imidazole ring, a triazole ring, or an oxadiazole ring.

[0345] The heteroaromatic ring also includes a fused heteroaromatic ring having a fused ring structure, such as a quinoline ring, a benzoquinoline ring, a quinoxaline ring, a dibenzoquinoxaline ring, a quinazoline ring, a benzoquinazoline ring, a dibenzoquinazoline ring, a phenanthroline ring, a phlodiazin ring, or a benzimidazole ring.

[0346] Among heteroaromatic compounds containing one or more of nitrogen, oxygen, and sulfur in addition to carbon, examples of heteroaromatic compounds having a five-membered ring structure include heteroaromatic compounds having an imidazole ring, heteroaromatic compounds having a triazole ring, heteroaromatic compounds having an oxazole ring, heteroaromatic compounds having an oxadiazole ring, heteroaromatic compounds having a thiazole ring, and heteroaromatic compounds having a benzimidazole ring.

[0347] Furthermore, among heteroaromatic compounds containing one or more of nitrogen, oxygen, and sulfur in addition to carbon, examples of heteroaromatic compounds having a six-membered ring structure include heteroaromatic compounds having a heteroaromatic ring such as a pyridine ring, a diazine ring (including a pyrimidine ring, a pyrazine ring, and a pyridazine ring), a triazine ring, and an azole ring.Heteroaromatic compounds having a structure in which pyridine rings are linked include heteroaromatic compounds having a bipyridine structure and heteroaromatic compounds having a terpyridine structure.

[0348] Furthermore, examples of heteroaromatic compounds having a fused ring structure partially containing the above-mentioned 6-membered ring structure include heteroaromatic compounds having a fused heteroaromatic ring such as a quinoline ring, a benzoquinoline ring, a quinoxaline ring, a dibenzoquinoxaline ring, a phenanthroline ring, a furodiazine ring (including a structure in which an aromatic ring is fused to the furan ring of a furodiazine ring), and a benzimidazole ring.

[0349] Specific examples of the heteroaromatic compound having a five-membered ring structure (such as an azole ring (including an imidazole ring, a triazole ring, and an oxadiazole ring), an oxazole ring, a thiazole ring, and a benzimidazole ring) include 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, Examples include 4-triazole (abbreviation: TAZ), 3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1,2,4-triazole (abbreviation: p-EtTAZ), 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), and 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOS).

[0350] Specific examples of the heteroaromatic compound having a 6-membered ring structure (including heteroaromatic rings having a pyridine ring, a diazine ring, a triazine ring, or the like) include heteroaromatic compounds having a pyridine ring, such as 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy) and 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), PCCzPTzn, 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazol-9-yl, and the like. mPCCzPTzn-02), 5-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviation: mINc(II)PTzn), 2-[3'-(triphenylen-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mTpBPTzn), 2-(biphenyl-4-yl)-4-phenyl-6-(9,9'-spirobi[9H-fluoren]-2-yl)-1,3,5-triazine (abbreviation: BP-S FTzn), 2,6-bis(4-naphthalen-1-ylphenyl)-4-[4-(3-pyridyl)phenyl]pyrimidine (abbreviated as 2,4NP-6PyPPm), 3-[9-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]-9-phenyl-9H-carbazole (abbreviated as PCDBfTzn), 2-(biphenyl-3-yl)-4-phenyl-6-{8-[(1,1':4',1''-terphenyl)-4-yl]-1-dibenzofuranyl}-1,3,5-triazine (abbreviated as mBP-TPDBfTzn), 2-{3 Heteroaromatic compounds containing heteroaromatic rings with a triazine ring, such as -[3-(dibenzothiophen-4-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mDBtBPTzn) and mFBPTzn, 4,6-bis[3-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(dibenzothiophen-4-yl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), 4,6mCzBP2Pm, 6-(biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviated as 6mBP-4Cz2PPm), 4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenyl-6-(biphenyl-4-yl)pyrimidine (abbreviated as 6BP-4Cz2PPm), 4-[3-(dibenzothiophen-4-yl)phenyl]-8-(naphthalen-2-yl)-[1]benzofuro[3,2-d]pyrimidine (abbreviated as 8βN-4mDBtPBfpm), 8BP-4mDBtPBfpm, 9mDBtBPNfpr, 9pmDBtBPNfpr, 3,8-bis[3-(dibenzothiophen-4-yl)phenyl] and heteroaromatic compounds containing a heteroaromatic ring having a diazine (pyrimidine) ring, such as 4,8-bis[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 4,8mDBtP2Bfpm), 8-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[3,2-d]pyrimidine (abbreviation: 8mDBtBPNfpm), and 8-[(2,2'-binaphthalen)-6-yl]-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8(βN2)-4mDBtPBfpm). The aromatic compounds containing heteroaromatic rings include heteroaromatic compounds having condensed heteroaromatic rings.

[0351] Other examples include heteroaromatic compounds containing a heteroaromatic ring with a diazine (pyrimidine) ring, such as 2,2'-(pyridine-2,6-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 2,6(P-Bqn)2Py), 6,6'(P-Bqn)2BPy, 2,2'-(pyridine-2,6-diyl)bis{4-[4-(2-naphthyl)phenyl]-6-phenylpyrimidine} (abbreviation: 2,6(NP-PPm)2Py), and 6mBP-4Cz2PPm; and heteroaromatic compounds containing a heteroaromatic ring having a triazine ring, such as 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn), 2,4,6-tris(2-pyridyl)-1,3,5-triazine (abbreviation: 2Py3Tzn), and 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn).

[0352] Specific examples of the heteroaromatic compound having a fused ring structure partially containing a 6-membered ring structure (heteroaromatic compound having a fused ring structure) include bathophenanthroline (abbreviation: BPhen), bathocuproine (abbreviation: BCP), NBPhen, mPPhen2P, 2,2'-biphenyl-4,4'-diylbis(9-phenyl-1,10-phenanthroline) (abbreviation: PPhen2BP), 2,6(P-Bqn)2Py, 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: 2mDBTBP and heteroaromatic compounds having a quinoxaline ring, such as 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), and 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 2mpPCBPDBq, etc.

[0353] In addition to the heteroaromatic compounds listed above, the electron transport layer can also include the following metal complexes: metal complexes having a quinoline ring or a benzoquinoline ring, such as tris(8-quinolinolato)aluminum(III) (abbreviation: Alq3), Almq3, 8-quinolinolato-lithium (abbreviation: Liq), BeBq2, bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (abbreviation: BAlq), and bis(8-quinolinolato)zinc(II) (abbreviation: Znq); and metal complexes having an oxazole ring or a thiazole ring, such as bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO) and bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ).

[0354] In addition, polymer compounds such as poly(2,5-pyridinediyl) (abbreviation: PPy), poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)] (abbreviation: PF-Py), and poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2'-bipyridine-6,6'-diyl)] (abbreviation: PF-BPy) can also be used as electron transport materials.

[0355] The electron transport layer may have not only a single layer structure but also a structure in which two or more layers made of the above-mentioned substances are stacked.

[0356] <Configuration of Electron Injection Layer> The electron injection layer 115 may be a layer containing an alkali metal, alkaline earth metal, rare earth metal, such as lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF), 8-quinolinolato-lithium (abbreviated as Liq), or ytterbium (Yb), or a compound or complex thereof. The electron injection layer 115 may be a layer made of a substance having electron transport properties containing an alkali metal, alkaline earth metal, or a compound thereof, or may be an electride. Examples of electrides include a mixed oxide of calcium and aluminum to which electrons are highly added.

[0357] Note that a layer containing a fluoride of the alkali metal or alkaline earth metal in a concentration (50 wt % or more) sufficient to form a microcrystalline state in a substance having an electron transport property (preferably an organic compound having a bipyridine skeleton) can also be used as the electron-injection layer 115. Since this layer has a low refractive index, it is possible to provide a light-emitting device with better external quantum efficiency.

[0358] The organic compound of one embodiment of the present invention described in Embodiment 1 can be used for the electron-injection layer 115. The electron-injection layer 115 may contain a substance having an electron-transport property in addition to the organic compound of one embodiment of the present invention described in Embodiment 1.

[0359] <<Configuration of the second electrode>> The second electrode 102 is an electrode including a cathode. The second electrode 102 may have a laminated structure, in which case the layer in contact with the organic compound layer 103 functions as the cathode. Materials that form the cathode include metals, alloys, electrically conductive compounds, and mixtures thereof, each having a low work function (specifically, 3.8 eV or less). Specific examples of such cathode materials include alkali metals such as lithium (Li) or cesium (Cs), elements belonging to Group 1 or Group 2 of the periodic table such as magnesium (Mg), calcium (Ca), and strontium (Sr), alloys containing these elements (MgAg, AlLi), rare earth metals such as europium (Eu) and ytterbium (Yb), and alloys containing these elements. However, by providing an electron injection layer between the second electrode 102 and the electron transport layer, various conductive materials such as Al, Ag, ITO, and indium oxide-tin oxide containing silicon or silicon oxide can be used as the cathode regardless of the magnitude of the work function.

[0360] When the second electrode 102 is formed using a material that is transparent to visible light, a light-emitting device that emits light from the second electrode 102 side can be obtained.

[0361] These conductive materials can be formed into films by dry methods such as vacuum deposition or sputtering, inkjet methods, spin coating, etc. Alternatively, they may be formed by wet methods using a sol-gel method, or by wet methods using a paste of a metal material.

[0362] In addition, various methods, whether dry or wet, can be used to form the organic compound layer 103. For example, vacuum deposition, gravure printing, offset printing, screen printing, inkjet printing, spin coating, or the like may be used.

[0363] Furthermore, the above-mentioned electrodes or layers may be formed using different film formation methods.

[0364] 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.

[0365] (Embodiment 3) 9A and 9B, 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.

[0366] 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.

[0367] 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.

[0368] 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).

[0369] 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.

[0370] 9A 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.

[0371] 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.

[0372] 9(A) 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.

[0373] Fig. 9(B) is an example of a cross-sectional view taken along dashed line A1-A2 in Fig. 9(A). As shown in Fig. 9(B), 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.

[0374] 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.

[0375] 9B 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.

[0376] 9(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.

[0377] 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.

[0378] 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.

[0379] 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 second electrode (common electrode) 102 on the common layer. The common layer 104 may or may not be provided, but is preferably provided because it can reduce damage to the organic compound layer 103R during processing. When the common layer 104 is provided, it is preferably 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.

[0380] 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 second electrode (common electrode) 102 on the common layer. The common layer 104 may or may not be provided, but is preferably provided because it can reduce 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.

[0381] 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 second electrode (common electrode) 102 on the common layer. The common layer 104 may or may not be provided, but is preferably provided because it can reduce 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.

[0382] 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.

[0383] The organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B are independent island-shaped layers for each device or for each emitted light 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.

[0384] The island-shaped organic compound layer 103 is formed by depositing an EL film and processing the EL film using a lithography method.

[0385] 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. 9B, 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, the conductive layer 151 preferably has high reflectivity for visible light, and the conductive layer 152 preferably 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.

[0386] 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.

[0387] 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.

[0388] 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.

[0389] 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.

[0390] 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.

[0391] 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.

[0392] Next, an example of a manufacturing method of the display device 100 having the structure shown in FIG. 9A will be described with reference to FIGS. 10A to 15C. The light-emitting device included in the display device 100 has an organic layer formed by a manufacturing process including treatment using water. By applying the light-emitting device of one embodiment of the present invention as the light-emitting device included in the display device of one embodiment of the present invention, a display device including a light-emitting device with reduced driving voltage and high emission efficiency can be provided.

[0393] [Example of manufacturing method] Thin films (insulating films, semiconductor films, conductive films, etc.) that make up display devices can be formed using methods such as sputtering, chemical vapor deposition (CVD), vacuum evaporation, pulsed laser deposition (PLD), or atomic layer deposition (ALD). CVD methods include plasma enhanced chemical vapor deposition (PECVD) and thermal CVD. One type of thermal CVD method is metal organic chemical vapor deposition (MOCVD).

[0394] Furthermore, thin films (insulating films, semiconductor films, conductive films, etc.) that constitute the display device can be formed by wet film formation methods such as spin coating, dipping, spray coating, inkjet, dispensing, screen printing, offset printing, doctor knife method, slit coating, roll coating, curtain coating, or knife coating.

[0395] In particular, vacuum processes such as vapor deposition and solution processes such as spin coating and inkjet printing can be used to fabricate light-emitting devices. Vapor deposition methods include physical vapor deposition (PVD) methods such as sputtering, ion plating, ion beam deposition, molecular beam deposition, and vacuum deposition, and chemical vapor deposition (CVD). In particular, functional layers included in the organic compound layer (e.g., hole injection layer, hole transport layer, hole blocking layer, light-emitting layer, electron blocking layer, electron transport layer, and electron injection layer) can be formed by vapor deposition (e.g., vacuum deposition), coating methods (e.g., dip coating, die coating, bar coating, spin coating, and spray coating), printing methods (e.g., inkjet printing, screen printing, offset printing, flexography, gravure printing, and microcontact printing).

[0396] Furthermore, when processing the thin film that constitutes the display device, it can be processed using, for example, a lithography method. Alternatively, the thin film may be processed using a nanoimprint method, a sandblasting method, a lift-off method, etc. Furthermore, the island-shaped thin film may be directly formed by a film formation method using a shielding mask such as a metal mask.

[0397] As a lithography method, for example, photolithography can be used. There are two typical photolithography methods: one is a method in which a resist mask is formed on a thin film to be processed, the thin film is processed by, for example, etching, and then the resist mask is removed; the other is a method in which a photosensitive thin film is formed, and then the thin film is exposed to light and developed to be processed into a desired shape.

[0398] In photolithography, the light used for exposure can be, for example, i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), or a mixture of these. Other light sources that can be used include ultraviolet light, KrF laser light, and ArF laser light. Exposure can also be performed by immersion exposure technology. Extreme ultraviolet (EUV) light or X-rays can also be used as the light used for exposure. An electron beam can also be used instead of the light used for exposure. Extreme ultraviolet light, X-rays, or an electron beam are preferred because they enable extremely fine processing. When exposure is performed by scanning a beam such as an electron beam, a photomask is not required.

[0399] The thin film can be etched by dry etching, wet etching, sandblasting, or the like.

[0400] In addition, in the process of creating light-emitting devices, organic compounds that absorb light and become excited are handled. Excited organic compounds may be highly likely to react with oxygen in the atmosphere or water. In other words, when light with a wavelength that the organic compound absorbs is irradiated in the presence of oxygen, degradation products may be generated in the organic compound.

[0401] Therefore, when processing a substrate on which an organic compound is formed by photolithography, if the processing involves exposure to the atmosphere, it is advisable to carry out the processing in an environment where the lighting is appropriately controlled. Ideally, the processing should be carried out under lighting with a wavelength that does not excite the organic compound that absorbs and becomes excited by light. However, in order to ensure illuminance or color rendering properties that do not reduce work efficiency, it is advisable to use lighting with an emission edge at the shortest wavelength of 600 nm or less, preferably 580 nm or less, in the emission edge of the light source's emission spectrum.

[0402] For example, it is preferable to use yellow light (fluorescent lamp or light-emitting diode (LED)) that does not emit light with a wavelength shorter than 500 nm for illumination. It is also preferable to use orange light (fluorescent lamp or light-emitting diode (LED)) that does not emit light with a wavelength shorter than 530 nm. A low-pressure sodium lamp can also be used. Lighting using an optical filter that can block light in the short wavelength range can also be used, and for example, incandescent lamps, fluorescent lamps, light-emitting diodes (LED), halogen lamps, and sunlight can be used. Examples of optical filters that can block light in the short wavelength range include band-pass filters and long-pass filters (short-wavelength cut filters). Furthermore, by using the above-mentioned lighting, the illuminance of the illumination light can be reduced.

[0403] 10(A), an insulating layer 171 is formed on a substrate (not shown). Subsequently, conductive layers 172 and 179 are formed on the insulating layer 171, and an insulating layer 173 is formed on the insulating layer 171 so as to cover the conductive layers 172 and 179. Subsequently, an insulating layer 174 is formed on the insulating layer 173, and an insulating layer 175 is formed on the insulating layer 174.

[0404] The substrate may be a substrate having heat resistance sufficient to withstand at least subsequent heat treatment. When an insulating substrate is used, a glass substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, an organic resin substrate, or the like may be used. Also, a semiconductor substrate such as a single-crystal semiconductor substrate made of silicon or silicon carbide, a polycrystalline semiconductor substrate, a compound semiconductor substrate such as silicon germanium, or an SOI substrate may be used.

[0405] 10A, openings are formed in the insulating layers 175, 174, and 173, reaching the conductive layer 172. Then, plugs 176 are formed to fill the openings.

[0406] 10A, a conductive film 151f, which will later become the conductive layers 151R, 151G, 151B, and 151C, is formed on the plug 176 and the insulating layer 175. The conductive film 151f can be formed by, for example, sputtering or vacuum evaporation. The conductive film 151f can be made of, for example, a metal material.

[0407] 10A, a conductive film 152f, which will later become the conductive layers 152R, 152G, 152B, and 152C, is formed over the conductive film 151f. The conductive film 152f can be formed by, for example, a sputtering method or a vacuum evaporation method. The conductive film 152f can be formed using, for example, a conductive oxide. Alternatively, the conductive film 152f can have a stacked structure of a film using a metal material and a film using a conductive oxide thereon. For example, the conductive film 152f can have a stacked structure of a film using titanium, silver, or an alloy containing silver and a film using a conductive oxide thereon.

[0408] The conductive film 152f can be formed by an ALD method. In this case, the conductive film 152f can be made of an oxide containing one or more elements selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon. The conductive film 152f can be formed by repeating a cycle consisting of introducing a precursor (which may be generally referred to as a precursor or metal precursor), purging the precursor, introducing an oxidizing agent (which may be generally referred to as a reactant, reactant, or non-metal precursor), and purging the oxidizing agent. When forming the conductive film 152f as an oxide film containing multiple metals, such as indium tin oxide, the metal composition can be controlled by varying the number of cycles for each type of precursor.

[0409] For example, when forming an indium tin oxide film as the conductive film 152f, an indium-containing precursor is introduced, the precursor is purged, an oxidizer is introduced, and an In—O film is formed. Next, a tin-containing precursor is introduced, the precursor is purged, and an oxidizer is introduced, and an Sn—O film is formed. Here, by increasing the number of cycles for forming the In—O film compared to the number of cycles for forming the Sn—O film, the number of In atoms contained in the conductive film 152f can be made larger than the number of Sn atoms.

[0410] Furthermore, for example, when a zinc oxide film is formed as the conductive film 152f, a Zn-O film is formed using the above procedure. For example, when an aluminum zinc oxide film is formed as the conductive film 152f, a Zn-O film and an Al-O film are formed using the above procedure. For example, when a titanium oxide film is formed as the conductive film 152f, a Ti-O film is formed using the above procedure. For example, when an indium tin oxide film containing silicon is formed as the conductive film 152f, an In-O film, an Sn-O film, and an Si-O film are formed using the above procedure. For example, when a zinc oxide film containing gallium is formed, a Ga-O film and a Zn-O film are formed using the above procedure.

[0411] Examples of precursors that can be used include indium-containing precursors such as triethylindium, trimethylindium, or [1,1,1-trimethyl-N-(trimethylsilyl)amido]-indium. Examples of precursors that can be used include tin chloride or tetrakis(dimethylamido)tin. Examples of precursors that can be used include zinc-containing precursors such as diethylzinc or dimethylzinc. Examples of precursors that can be used include gallium-containing precursors such as triethylgallium. Examples of precursors that can be used include titanium chloride, tetrakis(dimethylamido)titanium, or tetraisopropyl titanate. Examples of precursors that can be used include aluminum chloride or trimethylaluminum. Examples of precursors that can be used include silicon-containing precursors such as trisilylamine, bis(diethylamino)silane, tris(dimethylamino)silane, bis(tert-butylamino)silane, or bis(ethylmethylamino)silane. Examples of oxidizing agents include water vapor, oxygen plasma, or ozone gas.

[0412] 10A, a resist mask 191 is formed over the conductive film 151f and the conductive film 152f. The resist mask 191 can be formed by applying a photosensitive material (photoresist), exposing it to light, and developing it.

[0413] 10(B), for example, the conductive films 151f and 152f in regions that do not overlap with the resist mask 191 are removed by, for example, etching, specifically, dry etching, to form a pixel electrode including the conductive layer 151 and the conductive layer 152. Note that if the conductive film 151f includes a layer using a conductive oxide such as indium tin oxide, the layer may be removed by wet etching. As a result, the conductive layer 151 and the conductive layer 152 are formed. Note that, for example, when part of the conductive film 151f is removed by dry etching, a recess may be formed in a region of the insulating layer 175 that does not overlap with the conductive layer 151.

[0414] Note that the conductive film 152f may be processed by lithography to form the conductive layers 152R, 152G, 152B, and 152C, and then the conductive film 151f may be processed using the conductive layers 152R, 152G, 152B, and 152C as masks. Specifically, for example, after forming a resist mask, part of the conductive film 152f is removed by etching. The conductive film 152f can be removed by, for example, wet etching. The conductive film 152f may also be removed by dry etching. After that, the conductive film 151f may be removed by wet etching.

[0415] Here, it is preferable to perform hydrophobic treatment on the conductive layer 152. The hydrophobic treatment can change the surface to be treated from hydrophilic to hydrophobic, or can increase the hydrophobicity of the surface to be treated. By performing the hydrophobic treatment on the conductive layer 152, adhesion between the conductive layer 152 and the organic compound layer 103 formed in a later step can be improved, and film peeling can be suppressed. Note that the hydrophobic treatment is not necessarily performed.

[0416] 10(C), the resist mask 191 is removed. The resist mask 191 can be removed by ashing using oxygen plasma, for example. Alternatively, oxygen gas and a Group 18 element such as CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, or He may be used. Alternatively, the resist mask 191 may be removed by wet etching.

[0417] 10(D), an insulating film 156f, which will later become the insulating layer 156R, the insulating layer 156G, the insulating layer 156B, and the insulating layer 156C, is formed on the conductive layer 151R and the conductive layer 152R, the conductive layer 151G and the conductive layer 152G, the conductive layer 151B and the conductive layer 152B, the conductive layer 151C and the conductive layer 152C, and the insulating layer 175. The insulating film 156f can be formed by, for example, a CVD method, an ALD method, a sputtering method, or a vacuum deposition method.

[0418] The insulating film 156f can be formed using an inorganic material. For example, the insulating film 156f can be formed using an inorganic insulating film such as an oxide insulating film, a nitride insulating film, an oxynitride insulating film, or a nitride oxide insulating film. For example, the insulating film 156f can be formed using an oxide insulating film containing silicon, a nitride insulating film, an oxynitride insulating film, or a nitride oxide insulating film. For example, the insulating film 156f can be formed using silicon oxynitride.

[0419] 10(E), the insulating film 156f is processed to form insulating layers 156R, 156G, 156B, and 156C. For example, the insulating layer 156 can be formed by uniformly etching the upper surface of the insulating film 156f. Such uniform etching and planarization is also called an etch-back process. The insulating layer 156 may also be formed using lithography.

[0420] Next, as shown in FIG. 11(A), an organic compound film 103Rf, which will later become the organic compound layer 103R, is formed on the conductive layer 152R, the conductive layer 152G, the conductive layer 152B, the insulating layer 156R, the insulating layer 156G, the insulating layer 156B, and the insulating layer 175.

[0421] 11(A), the organic compound film 103Rf is not formed on the conductive layer 152C. For example, by using a mask for defining the film formation area (also called an area mask or a rough metal mask to distinguish it from a fine metal mask), the organic compound film 103Rf can be formed only in the desired region. By employing a film formation process using an area mask and a processing process using a resist mask, the light-emitting device can be manufactured through a relatively simple process.

[0422] The organic compound film 103Rf can be formed by, for example, a vapor deposition method, specifically a vacuum deposition method, or may be formed by a transfer method, a printing method, an inkjet method, a coating method, or the like.

[0423] Next, as shown in FIG. 11(A), a sacrificial film 158Rf, which will later become the sacrificial layer 158R, and a mask film 159Rf, which will later become the mask layer 159R, are formed in this order on the organic compound film 103Rf, the conductive layer 152C, and the insulating layer 175.

[0424] In this embodiment, an example is shown in which the mask film is formed with a two-layer structure of the sacrificial film 158Rf and the mask film 159Rf, but the mask film may have a single-layer structure or a laminated structure of three or more layers. Also, in this specification, the mask layer may be referred to as a sacrificial layer.

[0425] By providing a sacrificial layer on the organic compound film 103Rf, damage to the organic compound film 103Rf during the manufacturing process of the display device can be reduced, and the reliability of the light-emitting device can be improved.

[0426] The sacrificial film 158Rf is made of a film that is highly resistant to the processing conditions of the organic compound film 103Rf, specifically, a film that has a large etching selectivity with respect to the organic compound film 103Rf.The mask film 159Rf is made of a film that has a large etching selectivity with respect to the sacrificial film 158Rf.

[0427] The sacrificial film 158Rf and the mask film 159Rf are formed at a temperature lower than the heat-resistant temperature of the organic compound film 103Rf. The substrate temperatures when forming the sacrificial film 158Rf and the mask film 159Rf are typically 200° C. or lower, preferably 150° C. or lower, more preferably 120° C. or lower, more preferably 100° C. or lower, and even more preferably 80° C. or lower.

[0428] The sacrificial film 158Rf and the mask film 159Rf are preferably made of films that can be removed by wet etching, which can reduce damage to the organic compound film 103Rf when processing the sacrificial film 158Rf and the mask film 159Rf compared to when dry etching is used.

[0429] The sacrificial film 158Rf and the mask film 159Rf can be formed by, for example, sputtering, ALD (thermal ALD, PEALD), CVD, or vacuum deposition. Alternatively, they may be formed by the wet film formation method described above.

[0430] The sacrificial film 158Rf formed on and in contact with the organic compound film 103Rf is preferably formed using a formation method that causes less damage to the organic compound film 103Rf than the mask film 159Rf. For example, it is preferable to form the sacrificial film 158Rf using the ALD method or the vacuum deposition method rather than the sputtering method.

[0431] The sacrificial film 158Rf and the mask film 159Rf may each be made of one or more of a metal film, an alloy film, a metal oxide film, a semiconductor film, an organic insulating film, an inorganic insulating film, or the like.

[0432] The sacrificial film 158Rf and the mask film 159Rf can be made of metal materials such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, and tantalum, or alloy materials containing such metal materials. It is particularly preferable to use a low-melting-point material such as aluminum or silver. Using a metal material capable of blocking ultraviolet rays for one or both of the sacrificial film 158Rf and the mask film 159Rf is preferable because it can prevent ultraviolet rays from being irradiated onto the organic compound film 103Rf and suppress deterioration of the organic compound film 103Rf.

[0433] Furthermore, for the sacrificial film 158Rf and the mask film 159Rf, metal oxides such as In-Ga-Zn oxide, indium oxide, In-Zn oxide, In-Sn oxide, indium titanium oxide (In-Ti oxide), indium tin zinc oxide (In-Sn-Zn oxide), indium titanium zinc oxide (In-Ti-Zn oxide), indium gallium tin zinc oxide (In-Ga-Sn-Zn oxide), and indium tin oxide containing silicon can be used, respectively.

[0434] In addition, instead of the above gallium, an element M (M is one or more elements selected from aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium) may be used.

[0435] Furthermore, it is preferable to use a film containing a material that has light-shielding properties against light, particularly ultraviolet light, as the sacrificial film and the mask film. As the light-shielding material, various materials such as metals, insulators, semiconductors, and semimetals that have light-shielding properties against ultraviolet light can be used, but since part or all of the sacrificial film and the mask film will be removed in a later step, it is preferable that the film be a film that can be processed by etching, and it is particularly preferable that the film have good processability.

[0436] For the sacrificial film and mask film, semiconductor materials such as silicon or germanium are preferably used because they have high compatibility with semiconductor manufacturing processes. Alternatively, oxides or nitrides of the above semiconductor materials can be used. Alternatively, non-metallic materials such as carbon or their compounds can be used. Alternatively, metals such as titanium, tantalum, tungsten, chromium, and aluminum, or alloys containing one or more of these, can be used. Alternatively, oxides containing the above metals such as titanium oxide or chromium oxide, or nitrides such as titanium nitride, chromium nitride, or tantalum nitride can be used.

[0437] By using a film containing a material that blocks ultraviolet light for the sacrificial film and the mask film, it is possible to prevent the organic compound layer from being irradiated with ultraviolet light during, for example, an exposure process, and by preventing the organic compound layer from being damaged by ultraviolet light, the reliability of the light-emitting device can be improved.

[0438] It should be noted that a film containing a material that has a light-shielding property against ultraviolet rays can also achieve the same effect when used as the material for the inorganic insulating film 125f, which will be described later.

[0439] Moreover, various inorganic insulating films can be used for the sacrificial film 158Rf and the mask film 159Rf. In particular, oxide insulating films are preferable because they have higher adhesion to the organic compound film 103Rf than nitride insulating films. For example, inorganic insulating materials such as aluminum oxide, hafnium oxide, and silicon oxide can be used for the sacrificial film 158Rf and the mask film 159Rf. For example, aluminum oxide films can be formed as the sacrificial film 158Rf and the mask film 159Rf using the ALD method. Using the ALD method is preferable because it can reduce damage to the underlying layer (especially the organic compound layer).

[0440] For example, the sacrificial film 158Rf can be an inorganic insulating film (e.g., an aluminum oxide film) formed using the ALD method, and the mask film 159Rf can be an inorganic film (e.g., an In-Ga-Zn oxide film, an aluminum film, or a tungsten film) formed using the sputtering method.

[0441] The same inorganic insulating film can be used for both the sacrificial film 158Rf and the inorganic insulating layer 125 to be formed later. For example, an aluminum oxide film formed using the ALD method can be used for both the sacrificial film 158Rf and the inorganic insulating layer 125. The sacrificial film 158Rf and the inorganic insulating layer 125 may be formed under the same or different film-forming conditions. For example, by forming the sacrificial film 158Rf under the same conditions as the inorganic insulating layer 125, the sacrificial film 158Rf can be an insulating layer with high barrier properties against at least one of water and oxygen. On the other hand, since the sacrificial film 158Rf is a layer that will be mostly or completely removed in a later process, it is preferable that it be easily processed. For this reason, the sacrificial film 158Rf is preferably formed under conditions where the substrate temperature during film formation is lower than that of the inorganic insulating layer 125.

[0442] An organic material may be used for one or both of the sacrificial film 158Rf and the mask film 159Rf. For example, the organic material may be a material that is soluble in a chemically stable solvent, at least for the film located at the top of the organic compound film 103Rf. Materials that dissolve in water or alcohol are particularly suitable. When forming a film of such a material, it is preferable to apply the material dissolved in a solvent such as water or alcohol by a wet film formation method, and then perform a heat treatment to evaporate the solvent. In this case, performing the heat treatment under a reduced pressure atmosphere is preferable because it allows the solvent to be removed at a low temperature and in a short time, thereby reducing thermal damage to the organic compound film 103Rf.

[0443] The sacrificial film 158Rf and the mask film 159Rf may each be made of an organic resin such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, alcohol-soluble polyamide resin, or a fluororesin such as a perfluoropolymer.

[0444] For example, the sacrificial film 158Rf may be an organic film (e.g., a PVA film) formed using either a vapor deposition method or the above-mentioned wet film formation method, and the mask film 159Rf may be an inorganic film (e.g., a silicon nitride film) formed using a sputtering method.

[0445] 11(A), a resist mask 190R is formed on the mask film 159Rf. The resist mask 190R can be formed by applying a photosensitive material (photoresist) and then performing exposure and development.

[0446] The resist mask 190R may be made of either a positive resist material or a negative resist material.

[0447] The resist mask 190R is provided in a position overlapping with the conductive layer 152R. The resist mask 190R is preferably also provided in a position overlapping with the conductive layer 152C. This can prevent the conductive layer 152C from being damaged during the manufacturing process of the display device. Note that the resist mask 190R does not necessarily have to be provided on the conductive layer 152C. Furthermore, as shown in the cross-sectional view between B1 and B2 in FIG. 11A, the resist mask 190R is preferably provided so as to cover from the end of the organic compound film 103Rf to the end of the conductive layer 152C (the end on the organic compound film 103Rf side).

[0448] 11(B), a resist mask 190R is used to remove a portion of the mask film 159Rf to form a mask layer 159R. The mask layer 159R remains on the conductive layer 152R and the conductive layer 152C. The resist mask 190R is then removed. The mask layer 159R is used as a mask (also referred to as a hard mask) to remove a portion of the sacrificial film 158Rf to form a sacrificial layer 158R.

[0449] The sacrificial film 158Rf and the mask film 159Rf can be processed by wet etching or dry etching, respectively. The sacrificial film 158Rf and the mask film 159Rf are preferably processed by isotropic etching.

[0450] By using the wet etching method, damage to the organic compound film 103Rf during processing of the sacrificial film 158Rf and the mask film 159Rf can be reduced compared to when using the dry etching method. When using the wet etching method, it is preferable to use a chemical solution such as a developer, a tetramethylammonium hydroxide aqueous solution (TMAH), diluted hydrofluoric acid, oxalic acid, phosphoric acid, acetic acid, nitric acid, or a mixture thereof.

[0451] In processing the mask film 159Rf, the organic compound film 103Rf is not exposed, so the range of processing methods to be selected is wider than in processing the sacrificial film 158Rf. Specifically, even when a gas containing oxygen is used as an etching gas in processing the mask film 159Rf, deterioration of the organic compound film 103Rf can be further suppressed.

[0452] Furthermore, when dry etching is used to process the sacrificial film 158Rf, deterioration of the organic compound film 103Rf can be suppressed by not using a gas containing oxygen as the etching gas. When dry etching is used, it is preferable to use a gas containing a Group 18 element such as CF4, C4F8, SF6, CHF3, Cl2, HO, BCl3, or He as the etching gas.

[0453] For example, when an aluminum oxide film formed by ALD is used as the sacrificial film 158Rf, a portion of the sacrificial film 158Rf can be removed by dry etching using CHF3 and He, or CHF3, He, and CH4. When an In-Ga-Zn oxide film formed by sputtering is used as the mask film 159Rf, a portion of the mask film 159Rf can be removed by wet etching using diluted phosphoric acid. Alternatively, a portion of the mask film 159Rf may be removed by dry etching using CH4 and Ar. Alternatively, a portion of the mask film 159Rf can be removed by wet etching using diluted phosphoric acid. When a tungsten film formed by sputtering is used as the mask film 159Rf, a portion of the mask film 159Rf can be removed by dry etching using SF6, CF4 and O2, or CF4, Cl2, and O2.

[0454] The resist mask 190R can be removed by the same method as the resist mask 191. For example, it can be removed by ashing using oxygen plasma. Alternatively, oxygen gas and a Group 18 element such as CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, or He may be used. Alternatively, the resist mask 190R may be removed by wet etching. At this time, since the sacrificial film 158Rf is located on the outermost surface and the organic compound film 103Rf is not exposed, damage to the organic compound film 103Rf can be suppressed in the process of removing the resist mask 190R. Furthermore, the range of options for removing the resist mask 190R can be expanded.

[0455] 11(B), the organic compound film 103Rf is processed to form the organic compound layer 103R. For example, the mask layer 159R and the sacrificial layer 158R are used as a hard mask to remove a part of the organic compound film 103Rf, thereby forming the organic compound layer 103R.

[0456] 11B, a stacked structure of the organic compound layer 103R, the sacrificial layer 158R, and the mask layer 159R remains on the conductive layer 152R. Also, the conductive layers 152G and 152B are exposed.

[0457] 11B shows an example in which the edge of the organic compound layer 103R is located inside the edge of the conductive layer 152R. This structure enables miniaturization of pixels, enabling the creation of a high-resolution display. Although not shown in FIG. 11B, the etching process may result in the formation of a recess in a region of the insulating layer 175 that does not overlap with the organic compound layer 103R.

[0458] As described above, the resist mask 190R is preferably provided to cover the area between the dashed-dotted lines B1-B2 from the end of the organic compound layer 103R to the end of the conductive layer 152C (the end on the organic compound layer 103R side). As a result, as shown in FIG. 11B, the sacrificial layer 158R and the mask layer 159R are provided to cover the area between the dashed-dotted lines B1-B2 from the end of the organic compound layer 103R to the end of the conductive layer 152C (the end on the organic compound layer 103R side). This prevents the insulating layer 175 from being exposed between the dashed-dotted lines B1-B2, for example. This prevents the conductive layer 179 from being exposed when parts of the insulating layers 175, 174, and 173 are removed by etching or the like. This prevents the conductive layer 179 from being unintentionally electrically connected to other conductive layers. For example, it is possible to prevent a short circuit between the conductive layer 179 and the second electrode 102 that will be formed in a later step.

[0459] The organic compound film 103Rf is preferably processed by anisotropic etching, particularly anisotropic dry etching, or wet etching may be used.

[0460] When dry etching is used, deterioration of the organic compound film 103Rf can be suppressed by not using an oxygen-containing gas as the etching gas.

[0461] Alternatively, an etching gas containing oxygen may be used. The etching rate can be increased by using an etching gas containing oxygen. Therefore, etching can be performed under low power conditions while maintaining a sufficiently high etching rate. This can reduce damage to the organic compound film 103Rf. Furthermore, problems such as adhesion of reaction products generated during etching can be reduced.

[0462] When dry etching is used, it is preferable to use a gas containing one or more of H2, CF4, C4F8, SF6, CHF3, Cl2, H2O, BCl3, or Group 18 elements such as He and Ar as the etching gas. Alternatively, it is preferable to use a gas containing one or more of these elements and oxygen as the etching gas. Alternatively, oxygen gas may be used as the etching gas. Specifically, for example, a gas containing H2 and Ar, or a gas containing CF4 and He can be used as the etching gas. Alternatively, for example, a gas containing CF4, He, and oxygen can be used as the etching gas. Alternatively, for example, a gas containing H2 and Ar, or a gas containing oxygen can be used as the etching gas.

[0463] As described above, in one embodiment of the present invention, the resist mask 190R is formed over the mask film 159Rf, and part of the mask film 159Rf is removed using the resist mask 190R to form the mask layer 159R. Then, part of the organic compound film 103Rf is removed using the mask layer 159R as a hard mask to form the organic compound layer 103R. Therefore, it can be said that the organic compound layer 103R is formed by processing the organic compound film 103Rf using a lithography method. Note that part of the organic compound film 103Rf may be removed using the resist mask 190R. Then, the resist mask 190R may be removed.

[0464] Next, it is preferable to perform, for example, a hydrophobic treatment on the conductive layer 152G. When processing the organic compound film 103Rf, for example, the surface state of the conductive layer 152G may change to a hydrophilic state. For example, by performing a hydrophobic treatment on the conductive layer 152G, it is possible to improve the adhesion between the conductive layer 152G and a layer (here, the organic compound layer 103G) formed in a later step, and to suppress film peeling. Note that the hydrophobic treatment is not necessarily required.

[0465] Next, as shown in FIG. 12(A), an organic compound film 103Gf, which will later become the organic compound layer 103G, is formed on the conductive layer 152G, the conductive layer 152B, the insulating layer 156R, the insulating layer 156G, the insulating layer 156B, the mask layer 159R, and the insulating layer 175.

[0466] The organic compound film 103Gf can be formed by the same method as that used to form the organic compound film 103Rf, and can have the same structure as the organic compound film 103Rf.

[0467] 12(A), a sacrificial film 158Gf, which will later become the sacrificial layer 158G, and a mask film 159Gf, which will later become the mask layer 159G, are sequentially formed on the organic compound film 103Gf and the mask layer 159R. A resist mask 190G is then formed. The materials and formation methods for the sacrificial film 158Gf and the mask film 159Gf are the same as those applicable to the sacrificial film 158Rf and the mask film 159Rf. The materials and formation methods for the resist mask 190G are the same as those applicable to the resist mask 190R.

[0468] The resist mask 190G is provided in a position overlapping with the conductive layer 152G.

[0469] 12(B), a resist mask 190G is used to remove a portion of the mask film 159Gf to form a mask layer 159G. The mask layer 159G remains on the conductive layer 152G. The resist mask 190G is then removed. The mask layer 159G is then used as a mask to remove a portion of the sacrificial film 158Gf to form a sacrificial layer 158G. The organic compound film 103Gf is then processed to form an organic compound layer 103G. For example, the mask layer 159G and the sacrificial layer 158G are used as hard masks to remove a portion of the organic compound film 103Gf to form the organic compound layer 103G.

[0470] 12B, a stacked structure of the organic compound layer 103G, the sacrificial layer 158G, and the mask layer 159G remains on the conductive layer 152G, and the mask layer 159R and the conductive layer 152B are exposed.

[0471] Next, it is preferable to perform, for example, a hydrophobic treatment on the conductive layer 152B. When processing the organic compound film 103Gf, for example, the surface state of the conductive layer 152B may change to a hydrophilic state. For example, by performing a hydrophobic treatment on the conductive layer 152B, it is possible to improve the adhesion between the conductive layer 152B and a layer (here, the organic compound layer 103B) formed in a later step, and to suppress film peeling. Note that the hydrophobic treatment is not necessarily required.

[0472] Next, as shown in FIG. 12(C), an organic compound film 103Bf, which will later become the organic compound layer 103B, is formed on the conductive layer 152B, the insulating layer 156R, the insulating layer 156G, the insulating layer 156B, the mask layer 159R, the mask layer 159G, and the insulating layer 175.

[0473] The organic compound film 103Bf can be formed by the same method as that used to form the organic compound film 103Rf, and can have the same structure as the organic compound film 103Rf.

[0474] 12(C), a sacrificial film 158Bf, which will later become the sacrificial layer 158B, and a mask film 159Bf, which will later become the mask layer 159B, are sequentially formed on the organic compound film 103Bf and the mask layer 159R. A resist mask 190B is then formed. The materials and formation methods for the sacrificial film 158Bf and the mask film 159Bf are the same as those applicable to the sacrificial film 158Rf and the mask film 159Rf. The materials and formation methods for the resist mask 190B are the same as those applicable to the resist mask 190R.

[0475] The resist mask 190B is provided in a position overlapping with the conductive layer 152B.

[0476] 12(D), a resist mask 190B is used to remove a portion of the mask film 159Bf to form a mask layer 159B. The mask layer 159B remains on the conductive layer 152B. The resist mask 190B is then removed. The mask layer 159B is then used as a mask to remove a portion of the sacrificial film 158Bf to form a sacrifici...

Claims

1. a first electrode, a second electrode, a light-emitting layer, and a first layer; the light-emitting layer is located between the first electrode and the second electrode; the first layer is located between the light-emitting layer and the second electrode; the first layer includes at least one of a metal and a metal compound, a first organic compound, and a second organic compound; a light-emitting device, wherein the peak wavelength of the PL spectrum of a mixed film having the first organic compound and the second organic compound is longer than the peak wavelength of the PL spectrum of a single film of the first organic compound and the peak wavelength of the PL spectrum of a single film of the second organic compound at room temperature.

2. a first electrode, a second electrode, a light-emitting layer, and a first layer; the light-emitting layer is located between the first electrode and the second electrode; the first layer is located between the light-emitting layer and the second electrode; the first layer includes at least one of a metal and a metal compound, a first organic compound, and a second organic compound; a light-emitting device, wherein the wavelength of the emission edge on the short wavelength side of the PL spectrum of the mixed film containing the first organic compound and the second organic compound is longer than the wavelength of the emission edge on the short wavelength side of the PL spectrum of a single film of the first organic compound and the wavelength of the emission edge on the short wavelength side of the PL spectrum of a single film of the second organic compound at room temperature.

3. a first electrode, a second electrode, a light-emitting layer, and a first layer; the light-emitting layer is located between the first electrode and the second electrode; the first layer is located between the light-emitting layer and the second electrode; the first layer includes at least one of a metal and a metal compound, a first organic compound, and a second organic compound; a light-emitting device, wherein the wavelength of the absorption edge on the long wavelength side of the absorption spectrum of a mixed film containing at least one of the metal and the metal compound, the first organic compound, and the second organic compound is longer than the wavelength of the absorption edge on the long wavelength side of the absorption spectrum of a single film of the first organic compound and the wavelength of the absorption edge on the long wavelength side of the absorption spectrum of a single film of the second organic compound at room temperature.

4. a first electrode, a second electrode, a first light-emitting layer, a first layer, and a second light-emitting layer; the first light-emitting layer and the second light-emitting layer are located between the first electrode and the second electrode; the first layer is located between the first light-emitting layer and the second light-emitting layer; the first layer includes at least one of a metal and a metal compound, a first organic compound, and a second organic compound; a light-emitting device, wherein the peak wavelength of the PL spectrum of a mixed film having the first organic compound and the second organic compound is longer than the peak wavelength of the PL spectrum of a single film of the first organic compound and the peak wavelength of the PL spectrum of a single film of the second organic compound at room temperature.

5. a first electrode, a second electrode, a first light-emitting layer, a first layer, and a second light-emitting layer; the first light-emitting layer and the second light-emitting layer are located between the first electrode and the second electrode; the first layer is located between the first light-emitting layer and the second light-emitting layer; the first layer includes at least one of a metal and a metal compound, a first organic compound, and a second organic compound; a light-emitting device, wherein the wavelength of the emission edge on the short wavelength side of the PL spectrum of the mixed film containing the first organic compound and the second organic compound is longer than the wavelength of the emission edge on the short wavelength side of the PL spectrum of a single film of the first organic compound and the wavelength of the emission edge on the short wavelength side of the PL spectrum of a single film of the second organic compound at room temperature.

6. a first electrode, a second electrode, a first light-emitting layer, a first layer, and a second light-emitting layer; the first light-emitting layer and the second light-emitting layer are located between the first electrode and the second electrode; the first layer is located between the first light-emitting layer and the second light-emitting layer; the first layer includes at least one of a metal and a metal compound, a first organic compound, and a second organic compound; a light-emitting device, wherein the wavelength of the absorption edge on the long wavelength side of the absorption spectrum of a mixed film containing at least one of the metal and the metal compound, the first organic compound, and the second organic compound is longer than the wavelength of the absorption edge on the long wavelength side of the absorption spectrum of a single film of the first organic compound and the wavelength of the absorption edge on the long wavelength side of the absorption spectrum of a single film of the second organic compound at room temperature.

7. In any one of claims 1 to 6, a second layer; the second layer is located between the first layer and the second electrode; the second layer includes a third organic compound and a fourth organic compound; the third organic compound is an organic compound having a π-electron-rich heteroaromatic ring or an aromatic amine, The fourth organic compound has at least one of a halogen group and a cyano group.

8. In any one of claims 1 to 6, A light-emitting device, wherein the LUMO level of the first organic compound is higher than the LUMO level of the second organic compound.

9. In any one of claims 1 to 6, A light-emitting device, wherein the HOMO level of the first organic compound is higher than the HOMO level of the second organic compound.

10. In any one of claims 1 to 6, The light-emitting device, wherein the first organic compound and the second organic compound each have a heteroaromatic ring.

11. In claim 10, a heteroaromatic ring of the first organic compound and a heteroaromatic ring of the second organic compound each independently include at least one of a pyridine ring, a pyrazine ring, a pyrimidine ring, a pyridazine ring, a triazine ring, an imidazole ring, a pyrazole ring, an oxazole ring, a thiazole ring, and a triazole ring.

12. In claim 10, The first organic compound has an electron donating group.

13. In claim 12, The light-emitting device, wherein the electron-donating group is at least one of an alkyl group, an alkoxy group, an aryloxy group, an alkylamino group, an arylamino group, and a heterocyclic amino group.

14. In any one of claims 1 to 6, The metal and metal compound comprises a metal belonging to Group 1, Group 3, Group 11 or Group 13 of the periodic table.

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