Light emitting device

Abstract

A light emitting device having good characteristics is provided. There is provided a light-emitting device including a first electrode, a second electrode, a light-emitting layer between the first electrode and the second electrode, and a first layer between the light-emitting layer and the second electrode, the first layer containing a first organic compound and a second organic compound, the first organic compound containing a metal and / or a metal compound, and the second organic compound containing a metal and / or a metal compound. The peak wavelength of the PL spectrum of the mixed film containing the first organic compound and the second organic compound is longer at room temperature than the peak wavelength of the PL spectrum of the single film of the first organic compound and the peak wavelength of the PL spectrum of the single film of the second organic compound.

Description

TECHNICAL FIELD

[0001] One embodiment of the present application relates to a light-emitting device, a light-emitting apparatus, a display apparatus, an electronic device, a lighting apparatus, and an electronic device. Note that one embodiment of the present application is not limited to the above technical field. The technical field of one embodiment of the present application disclosed in this specification and the like relates to an object, a method, or a manufacturing method. In addition, one embodiment of the present application relates to a process, a machine, manufacture, or a composition of matter. Thus, specifically, examples of the technical field of one embodiment of the present application disclosed in this specification include a semiconductor device, a display device, a liquid crystal display device, a light-emitting device, a lighting device, a power storage device, a storage device, an imaging device, an input device (e.g., a touch sensor), an input-output device (e.g., a touch panel), a method for driving any of the above devices, and a method for manufacturing any of the above devices. BACKGROUND

[0002] In recent years, display devices have been applied to a variety of uses. For example, as a use of a large display device, a household television device (also referred to as a television or a television receiver), a digital signage, and a PID (Public Information Display) and the like have been developed, and as a use of a small display device, a smartphone or a tablet terminal provided with a touch panel and the like have been developed.

[0003] In addition, there is also a demand for high definition of display devices. As an apparatus requiring a high-definition display device, an apparatus for virtual reality (VR), augmented reality (AR), substitutional reality (SR), and mixed reality (MR) and the like have been developed.

[0004] As a display element for a display device, development of a light-emitting device (also referred to as a light-emitting element) is increasingly active. A light-emitting device utilizing an electroluminescence (hereinafter referred to as EL) phenomenon (also referred to as an EL device, an EL element), and particularly an organic EL device using an organic compound has characteristics such as thinness, lightweight, a high-speed response to an input signal, and driving with a direct-current constant voltage source, and is thus preferably applied to a display device.

[0005] In order to obtain a more high-definition display device using an organic EL device, instead of an evaporation method using a metal mask, a technique of patterning an organic compound layer using a photolithography method has been developed. By using a photolithography method, a high-definition display device in which the interval of the organic compound layer is several μm can be obtained (see, for example, Patent Document 1).

[0006] [Patent Document 1] Japanese PCT International Application Translation No. 2018-521459 SUMMARY

[0007] It is common knowledge that the initial characteristics and reliability of the cathode and the organic compound layer in a previously known organic EL device are affected when exposed to atmospheric components such as water and oxygen, and thus an organic EL device is manufactured in an atmosphere of an inactive gas or an atmosphere close to a vacuum. On the other hand, when an organic EL device is manufactured, as described above, in a process of processing an organic compound layer using a photolithography method or the like (hereinafter, this process is sometimes referred to as a process using a photolithography technique), the organic compound layer is sometimes exposed to atmospheric components such as water and oxygen and water, a chemical solution, or the like used in the photolithography method. Therefore, there is a demand for development of an organic EL device including an organic compound layer having high resistance to the above-described environment.

[0008] One of objects of one embodiment of the present application is to provide a novel light-emitting device. One of objects of one embodiment of the present application is to provide a light-emitting device with high efficiency. One of objects of one embodiment of the present application is to provide a light-emitting device with high reliability. One of objects of one embodiment of the present application is to provide a light-emitting device with high efficiency and reliability.

[0009] One of objects of one embodiment of the present application is to provide a novel light-emitting device manufactured using a photolithography technique. One of objects of one embodiment of the present application is to provide a light-emitting device manufactured using a photolithography technique and with high efficiency. One of objects of one embodiment of the present application is to provide a light-emitting device manufactured using a photolithography technique and with high reliability. One of objects of one embodiment of the present application is to provide a light-emitting device manufactured using a photolithography technique and with high efficiency and reliability.

[0010] One of objects of one embodiment of the present application is to provide a novel light-emitting device that can be used for a high-definition display device. One of objects of one embodiment of the present application is to provide a light-emitting device that can be used for a high-definition display device and with high efficiency. One of objects of one embodiment of the present application is to provide a light-emitting device that can be used for a high-definition display device and with high reliability. One of objects of one embodiment of the present application is to provide a light-emitting device that can be used for a high-definition display device and with high efficiency and reliability.

[0011] Note that the description is not intended to limit the present application to other purposes. One embodiment of the present application does not necessarily achieve all the objects. Other objects can be apparent from the description, the attached drawings, and the claims.

[0012] One embodiment of the present application 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 positioned between the first electrode and the second electrode, the first layer is positioned 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 a peak wavelength of a PL spectrum of a mixed film including the first organic compound and the second organic compound is longer than a peak wavelength of a PL spectrum of a single film of the first organic compound and a peak wavelength of a PL spectrum of a single film of the second organic compound at room temperature.

[0013] One embodiment of the present application 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 positioned between the first electrode and the second electrode, the first layer is positioned 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 a wavelength of an emission end on the short-wavelength side of a PL spectrum of a mixed film including the first organic compound and the second organic compound is longer than a wavelength of an emission end on the short-wavelength side of a PL spectrum of a single film of the first organic compound and a wavelength of an emission end on the short-wavelength side of a PL spectrum of a single film of the second organic compound at room temperature.

[0014] One embodiment of the present application 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 positioned between the first electrode and the second electrode, the first layer is positioned between the light-emitting layer and the second electrode, the second light-emitting layer is positioned between the first 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 a peak wavelength of a PL spectrum of a mixed film including the first organic compound and the second organic compound is longer than a peak wavelength of a PL spectrum of a single film of the first organic compound and a peak wavelength of a PL spectrum of a single film of the second organic compound at room temperature.

[0015] One embodiment of the present application 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, wherein the first light-emitting layer and the second light-emitting layer are positioned between the first electrode and the second electrode, the first layer is positioned 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, and a wavelength of an emission end on a short-wavelength side of a 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 than a wavelength of an emission end on a short-wavelength side of a PL spectrum of a single film of the first organic compound and a wavelength of an emission end on a short-wavelength side of a PL spectrum of a single film of the second organic compound at room temperature.

[0016] One embodiment of the present application 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 positioned between the first electrode and the second electrode, the first layer is positioned 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 a peak wavelength of a 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 than a peak wavelength of a PL spectrum of a single film of the first organic compound and a peak wavelength of a PL spectrum of a single film of the second organic compound at room temperature.

[0017] One embodiment of the present application 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 positioned between the first electrode and the second electrode, the first layer is positioned 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 a wavelength of an emission end on a short-wavelength side of a 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 than a wavelength of an emission end on a short-wavelength side of a PL spectrum of a single film of the first organic compound and a wavelength of an emission end on a short-wavelength side of a PL spectrum of a single film of the second organic compound at room temperature.

[0018] One embodiment of the present application 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, wherein the first light-emitting layer and the second light-emitting layer are positioned between the first electrode and the second electrode, the first layer is positioned 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, and a peak wavelength of a 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 than a peak wavelength of a PL spectrum of a single film of the first organic compound and a peak wavelength of a PL spectrum of a single film of the second organic compound at room temperature.

[0019] One embodiment of the present application 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, wherein the first light-emitting layer and the second light-emitting layer are positioned between the first electrode and the second electrode, the first layer is positioned 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, and a wavelength of an emission end on a short wavelength side of a 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 than wavelengths of emission ends on a short wavelength side of a PL spectrum of a single film of the first organic compound and a PL spectrum of a single film of the second organic compound at room temperature.

[0020] One embodiment of the present application 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 positioned between the first electrode and the second electrode, the first layer is positioned 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 a wavelength of an absorption end on a long wavelength side of an absorption spectrum of a mixed film including the first organic compound and the second organic compound is longer than wavelengths of absorption ends on a long wavelength side of an absorption spectrum of a single film of the first organic compound and an absorption spectrum of a single film of the second organic compound at room temperature.

[0021] One embodiment of the present application 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, wherein the first light-emitting layer and the second light-emitting layer are positioned between the first electrode and the second electrode, the first layer is positioned 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, and a wavelength of an absorption end on a long wavelength side of an absorption spectrum of a mixed film including the first organic compound and the second organic compound is longer than wavelengths of absorption ends on a long wavelength side of an absorption spectrum of a single film of the first organic compound and an absorption spectrum of a single film of the second organic compound at room temperature.

[0022] One embodiment of the present application 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 positioned between the first electrode and the second electrode, the first layer is positioned 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 a wavelength of an absorption edge on a long-wavelength side of an absorption 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 than a wavelength of an absorption edge on a long-wavelength side of an absorption spectrum of a single film of the first organic compound and a wavelength of an absorption edge on a long-wavelength side of an absorption spectrum of a single film of the second organic compound at room temperature.

[0023] One embodiment of the present application 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, wherein the first light-emitting layer and the second light-emitting layer are positioned between the first electrode and the second electrode, the first layer is positioned 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, and a wavelength of an absorption edge on a long-wavelength side of an absorption 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 than a wavelength of an absorption edge on a long-wavelength side of an absorption spectrum of a single film of the first organic compound and a wavelength of an absorption edge on a long-wavelength side of an absorption spectrum of a single film of the second organic compound at room temperature.

[0024] In the light-emitting device of one embodiment of the present application having the above structure, a second layer is further included, wherein the second layer is positioned 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, and the fourth organic compound is an organic compound having at least one of a halogen group and a cyano group. Further, in the light-emitting device including the second light-emitting layer in the light-emitting device having the above structure, the second layer is preferably positioned between the first layer and the second light-emitting layer.

[0025] In the light-emitting device having the above structure, the LUMO level of the first organic compound is more preferably higher than the LUMO level of the second organic compound.

[0026] In the light-emitting device having the above structure, the HOMO level of the first organic compound is more preferably higher than the HOMO level of the second organic compound.

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

[0028] In the light-emitting device having the above structure, it is more preferable that the heteroaromatic ring possessed by the first organic compound and the heteroaromatic ring possessed by the second organic compound each independently have 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 the above structure, it is more preferable that the first organic compound have an electron-donating group.

[0030] In the light-emitting device having the above structure, it is more preferable that the electron-donating group be 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 device having the above structure, it is more preferable that the metal and the metal compound include a metal belonging to Group 1, Group 3, Group 11, or Group 13 of the periodic table.

[0032] One embodiment of the present application is a light-emitting device having the above structure, in which a third layer is included between the first layer and the second layer, and the thickness of the third layer is greater than 0 nm and is 10 nm or less.

[0033] One embodiment of the present application is a light-emitting device having the above structure, in which the first layer and the second layer are in contact.

[0034] In the light-emitting device having the above structure, it is more preferable that the light-emitting layer, the first light-emitting layer, or the second light-emitting layer include a light-emitting substance, and that the wavelength of the absorption end on the long-wavelength side of the absorption spectrum of the light-emitting substance be longer than the wavelength of the emission end on the short-wavelength side of the PL spectrum of a mixed film including the first organic compound and the second organic compound at room temperature.

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

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

[0037] According to one embodiment of the present application, a novel light-emitting device can be provided for use in a high-resolution display device. According to one embodiment of the present application, a light-emitting device can be provided for use in a high-resolution display device and having good efficiency. According to one embodiment of the present application, a light-emitting device can be provided for use in a high-resolution display device and having good reliability. According to one embodiment of the present application, a light-emitting device can be provided for use in a high-resolution display device and having good light-emitting efficiency and reliability.

[0038] Note that the description of these effects does not preclude the presence of other effects. One embodiment of the present application does not necessarily have all of the effects described above. Other effects can be derived from the description, drawings, claims, and the like. BRIEF DESCRIPTION OF DRAWINGS

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

[0040] Embodiments are described in detail with reference to the accompanying drawings. Note that the application is not limited to the following description, and it is readily apparent to those skilled in the art that the mode and details of the present application can be changed in various ways without departing from the spirit and technical scope thereof. Therefore, the present application should not be interpreted as being limited to the description of the embodiments below.

[0041] Note that, in the structure of the application described below, the same symbols are used to show the same parts or parts having the same function among different drawings, and repeated description thereof is omitted. Further, when showing parts having the same function, the same hatching is sometimes used without particularly adding the same symbol.

[0042] In addition, for convenience of explanation, the position, size, and range of each component shown in the drawings are not necessarily shown as the actual position, size, and range thereof. Therefore, the disclosed application is not necessarily limited to the position, size, and range disclosed in the drawings.

[0043] In addition, depending on the case or state, a "film" and a "layer" can be interchanged with each other. For example, a "conductive layer" can be changed into a "conductive film". Further, for example, an "insulating film" can be changed into an "insulating layer".

[0044] In this specification and the like, the number of a term such as "first", "second", and "third" is not limited to a specific number. For example, in some cases, there are two or more of the "first" and the "second". In addition, in some cases, there are three or more of the "first", the "second", and the "third". Therefore, the terms such as the "first", the "second", and the "third" do not mean a specific number but are used to to distinguish a component from another. For example, in the case where there are two or more of the "first" and the "second", there are "first" and "second" of a certain component, and there are "first" and "second" of another component. In this specification and the like, terms such as "first", "second", and "third" are not necessarily used to distinguish a component from another, and the components are sometimes not distinguished from one another using these terms. For example, when a certain component includes a component that is called the "first" and a component that is called the "second", such a component is not necessarily called the "first" and the "second".

[0045] Note that, in this specification and the like, a device manufactured using a metal mask or an FMM (Fine Metal Mask) is sometimes referred to as a device having an MM (Metal Mask) structure. Further, in this specification and the like, a device manufactured without using a metal mask or an FMM is sometimes referred to as a device having an MML (Metal Mask Less) structure.

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

[0047] Note that in this specification and the like, a tapered shape means a shape in which at least a part of a side surface of a component is inclined with respect to a substrate surface. For example, a region in which an angle (also referred to as a taper angle) formed by the inclined side surface and the substrate surface is less than 90 degrees is preferably a tapered region. Note that the side surface of the component and the substrate surface do not necessarily have to be completely flat, and can be an approximately planar shape with a slight curvature or an approximately planar shape with fine irregularities.

[0048] Embodiment 1 In this embodiment, a light-emitting element of one embodiment of the present application will be described with reference to FIG. 1A and FIG. 7 A light-emitting element of one embodiment of the present application will be described.

[0049] A light-emitting element of one embodiment of the present application will be described. FIG. 1A FIG. 1A shows a schematic view of two light-emitting elements, i.e., a light-emitting element 130a and a light-emitting element 130b, which are adjacent to each other and included in a light-emitting device. The light-emitting element 130a and the light-emitting element 130b are each a light-emitting element in which a part of an organic compound layer is processed by a lithography technique. Further, the light-emitting element 130a and the light-emitting element 130b are each a series type light-emitting element having a structure in which a plurality of light-emitting units are stacked with an interlayer therebetween.

[0050] The light-emitting element 130a is positioned over an insulating layer 175 and includes a first electrode 101a having an anode, a second electrode 102 having a cathode, and an organic compound layer 103a. The organic compound layer 103a is positioned between the first electrode 101a and the second electrode 102. Further, the organic compound layer 103a has a structure in which a first light-emitting unit 501a and a second light-emitting unit 502a are stacked with an interlayer 160a therebetween. The first light-emitting unit 501a includes a first light-emitting layer 113a_1. The interlayer 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 be said that the interlayer 160a is positioned between the first light-emitting layer 113a_1 and the second light-emitting layer 113a_2.

[0051] In the light emitting device 130a, the layers other than the electron injection layer 115 in the organic compound layer 103a are processed by a lithography technique. Therefore, the layers other than the electron injection layer 115 in the organic compound layer 103a are separated from the light emitting device 130b as the adjacent light emitting device. In addition, the end portions (contours) of the layers other than the electron injection layer 115 in the organic compound layer 103a are aligned or substantially aligned in the direction perpendicular 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 separated from 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. In addition, the end portions (contours) 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 substantially aligned in the direction perpendicular to the substrate.

[0052] The light emitting device 130b is located on the insulating layer 175 and includes the first electrode 101b having an anode, the second electrode 102 having a cathode, and the organic compound layer 103b. The organic compound layer 103b is located between the first electrode 101b and the second electrode 102. In addition, the organic compound layer 103b has a structure in which the first light emitting unit 501b and the second light emitting unit 502b are stacked with the intermediate layer 160b interposed therebetween. The first light emitting unit 501b includes the first light emitting layer 113b_1. The intermediate layer 160b includes the first layer 161b and the second layer 162b. The second light emitting unit 502b includes the second light emitting layer 113b_2 and the 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, the layers other than the electron injection layer 115 in the organic compound layer 103b are processed by a lithography technique. Therefore, the layers other than the electron injection layer 115 in the organic compound layer 103b are separated (or can also be said to be separated) from the light emitting device 130a as the adjacent light emitting device. In addition, the end portions (contours) of the layers other than the electron injection layer 115 in the organic compound layer 103b are aligned or substantially aligned in the direction perpendicular 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 separated 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. In addition, the end portions (contours) 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 substantially aligned in the direction perpendicular to the substrate.

[0054] The electron injection layer 115 and the second electrode 102 are preferably formed after the layers other than the electron injection layer 115 in the organic compound layer 103a and the layers other than the electron injection layer 115 in the organic compound layer 103b are processed using a lithography technique. That is, the electron injection layer 115 and the second electrode 102 are preferably continuous layers commonly used for the light emitting device 130a and the light emitting device 130b.

[0055] By using a material having a donor property, represented by an alkali metal, an alkaline earth metal, or a compound thereof, as the electron injection layer 115, it is possible to make the light emitting device low voltage, and thus it is preferable. However, when the organic compound layer including the above-mentioned donor substance is processed using a lithography technique, the driving voltage of the light emitting device can be greatly increased or the current efficiency can be significantly reduced due to the influence of oxygen or water in the atmosphere, a chemical solution or water used in the process.

[0056] On the other hand, as with the light emitting device 130a and the light emitting device 130b, by manufacturing the light emitting device in a method in which the electron injection layer 115 and the second electrode 102 are formed after the layers other than the electron injection layer 115 in the organic compound layer are processed using a lithography technique, the electron injection layer 115 is not easily affected by oxygen or water in the atmosphere, a chemical solution or water used in the process, and thus it is possible to realize a light emitting device having good characteristics.

[0057] In addition, in the case where the organic compound layer is processed using a lithography technique, it is possible to reduce the distance between the organic compound layers compared to the case where mask evaporation is performed. Specifically, it is possible to reduce the distance d between the layers other than the electron injection layer 115 of the organic compound layer 103a and the layers other than the electron injection layer 115 of the organic compound layer 103b 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. In addition, for example, by using an LSI exposure device, it is possible to reduce the distance d to, for example, 500 nm or less, 200 nm or less, 100 nm or less, or even 50 nm or less in the process on a silicon wafer.

[0058] In addition, it is preferable that an insulating layer be provided in the gap between the layers other than the electron injection layer 115 of the organic compound layer 103a and the layers other than the electron injection layer 115 of the organic compound layer 103b, and the layers other than the electron injection layer 115 of the organic compound layer 103a and the layers other than the electron injection layer 115 of the organic compound layer 103b are separated. At this time, the insulating layer has a region in contact with the electron injection layer 115 or the second electrode 102.

[0059] It is preferable that, in the light emitting device 130a, the first light emitting unit 501a includes the hole injection layer 111a, the first hole transport layer 112a_1, and the first electron transport layer 114a_1 in addition to the first light emitting layer 113a_1. Further, the second light emitting unit 502a preferably includes the second hole transport layer 112a_2 and the second electron transport layer 114a_2 in addition to the second light emitting layer 113a_2 and the electron injection layer 115. Further, the intermediate layer 160a can include the third layer 163a between the first layer 161a and the second layer 162a. Note that, in the case where the surface on the anode side of the light emitting unit contacts the intermediate layer 160a as in the second light emitting unit 502a, the second layer 162a on the cathode side in the intermediate layer 160a can also be used as the hole injection layer of the second light emitting unit 502a, and thus the hole injection layer can or can not be provided in the light emitting unit.

[0060] It is preferable that, in the light emitting device 130b, the first light emitting unit 501b includes the hole injection layer 111b, the first hole transport layer 112b_1, and the first electron transport layer 114b_1 in addition to the first light emitting layer 113b_1. Further, the second light emitting unit 502b preferably includes the second hole transport layer 112b_2 and the second electron transport layer 114b_2 in addition to the second light emitting layer 113b_2 and the electron injection layer 115. Further, the intermediate layer 160b can include the third layer 163b between the first layer 161b and the second layer 162b. Note that, in the case where the surface on the anode side of the light emitting unit contacts the intermediate layer 160b as in the second light emitting unit 502b, the second layer 162b on the cathode side in the intermediate layer 160b can also be used as the hole injection layer of the second light emitting unit 502b, and thus the hole injection layer can or can not be provided in the light emitting unit.

[0061] Further, as FIG. 1AAs shown, the topmost layer of each layer other than the electron injection layer 115 of the organic compound layer 103a is preferably the second electron transport layer 114a_2. Similarly, the topmost layer of each layer other than the electron injection layer 115 of the organic compound layer 103b is preferably the second electron transport layer 114b_2. When the second electron transport layer 114a_2 and the second electron transport layer 114b_2 are processed using lithography, for example, compared to the case where the second light-emitting layer 113a_2 and the second light-emitting layer 113b_2 are processed as the organic compound layer on which they are located, the second electron transport layer 114a_2 and the second electron transport layer 114b_2 are provided above the second light-emitting layer 113a_2 and the second light-emitting layer 113b_2, thereby making them less susceptible to the effects of oxygen or water in the atmosphere, or of chemical solutions or water used in the process. In other words, it is preferred to use lithography to process at least the layers above the second light-emitting layer 113a_2 and the second light-emitting layer 113b_2 of each organic compound layer. More preferably, the second electron transport layer 114a_2 and the second electron transport layer 114b_2 are processed using lithography as the topmost layers. This makes it easier to avoid degradation of the light-emitting device's characteristics caused by lithography manufacturing.

[0062] Note that although FIG. 1A In the example shown in FIG, each organic compound layer includes two light-emitting units, but one embodiment of the present invention is not limited thereto. Each organic compound layer may also include three or more light-emitting units. By stacking a plurality of light-emitting units with an intermediate layer between a pair of electrodes, it is possible to emit light with high brightness while maintaining a low current density, thereby realizing a light-emitting device with higher reliability. In addition, a light-emitting device with low power consumption can also be realized. In addition, although FIG. 1A Although not shown in the figure, each light-emitting unit may further include a hole injection layer, a hole transport layer, an electron blocking layer, a hole blocking layer, an electron transport layer, an electron injection layer, etc. In addition, each layer may be a stack of two or more layers.

[0063] Note that in this specification, the structure of one of the light-emitting device 130a and the light-emitting device 130b is sometimes shown, but the other one of the light-emitting device 130a and the light-emitting device 130b may have the same structure.

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

[0065] exist FIG. 1A In the light-emitting device 130a shown, by applying a voltage between a pair of electrodes (the first electrode 101a and the 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 current to flow. In addition, electrons are injected from the first layer 161a 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 on the cathode side of the intermediate layer 160a into the second hole transport layer 112a_2 in the second light-emitting unit 502a. Furthermore, the injected carriers (electrons and holes) recombine to form excitons. When the carriers (electrons and holes) in the first light-emitting layer 113a_1 and the second light-emitting layer 113a_2 containing the light-emitting material recombine to form excitons, the light-emitting material contained in the first light-emitting layer 113a_1 and the second light-emitting layer 113a_2 is in an excited state, and light can be emitted from the light-emitting material.

[0066] In addition, if FIG. 1A As shown, the first layer 161a on the anode side of the intermediate layer 160a is preferably adjacent to the first electron transport layer 114a_1 and disposed between the first electron transport layer 114a_1 and the second light-emitting unit 502a. By adopting this structure, electrons can be efficiently injected into the first light-emitting unit 501a.

[0067] Here, in order to reduce the driving voltage of the light-emitting device and achieve efficient light emission, it is preferred to reduce the electron injection barrier from the intermediate layer to the first electron transport layer so that the electrons generated in the intermediate layer are smoothly injected and transported to the first electron transport layer. For this reason, generally speaking, as the first layer of the intermediate layer, an alkali metal or alkaline earth metal and its compound with a small work function are used. However, the metal and the compound are easily degraded by oxygen or water in the atmosphere and water or liquid medicine used in the process using lithography technology, resulting in a significant increase in the driving voltage of the light-emitting device or a significant decrease in the current efficiency. In addition, it is conceivable to use a metal that is stable to oxygen and water in the atmosphere and resistant to water and liquid medicine for the first layer of the intermediate layer. Such a metal is stable and has low electron injection properties. Therefore, it is possible to form 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 the luminous efficiency.

[0068] in addition, FIG. 2 yes FIG. 1AA schematic view of a modification example of the light emitting device 130a and the light emitting device 130b. The light emitting device 130a and the light emitting device 130b are both light emitting devices in which the entire organic compound layer including the electron injection layer is processed by a lithography technique.

[0069] FIG. 2 The organic compound layer 103a of the light emitting device 130a is separated from the light emitting device 130b which is an adjacent light emitting device, and includes the electron injection layer 115a having an end portion (profile) aligned or substantially aligned with other layers in a direction perpendicular to the substrate. Further, FIG. 2 The organic compound layer 103b of the light emitting device 130b is separated from the light emitting device 130a which is an adjacent light emitting device, and includes the electron injection layer 115b having an end portion (profile) aligned or substantially aligned with other layers in a direction perpendicular to the substrate. Note that, FIG. 2 The constituent elements of the light emitting device 130a, the light emitting device 130b, and the periphery thereof are the same as those of the light emitting device 130 shown in FIG. 1, and thus a description thereof is omitted. FIG. 1A The constituent elements shown are the same, and thus a description thereof is omitted.

[0070] As FIG. 2 In the light emitting device in which the entire organic compound layer including the electron injection layer is processed by a lithography technique, it is preferable to use a material resistant to water and a chemical liquid used in a process for the electron injection layer and the intermediate layer.

[0071] Thus, in one embodiment of the present application, there is provided a light emitting device in which any of a first layer (161a, 161b) of the above-described intermediate layer (160a, 160b) and an electron injection layer (115, 115a, 115b) employs a structure of a layer 200 described below.

[0072] [Layer 200] As FIG. 1B The layer 200 contains a metal or a metal compound 161_M, a first organic compound 161_1, and a second organic compound 161_2. In this composite material, the metal or the metal compound 161_M interacts with the first organic compound 161_1 to form a donor energy level (SOMO (Singly Occupied Molecular Orbital) energy level or HOMO (Highest Occupied Molecular Orbital) energy level), and thus can function as an electron donor for the second organic compound 161_2. By employing such a structure, a layer having excellent electron injection properties and being resistant to oxygen and water in the atmosphere and water and a chemical liquid used in a process using a lithography technique can be formed.

[0073] Further, as the layer 200, it is preferable to use a mixed layer containing the metal or metal compound 161_M, the first organic compound 161_1, and the second organic compound 161_2. By using the mixed layer of the metal or metal compound 161_M, the first organic compound 161_1, and the second organic compound 161_2 as the layer 200, the above substances easily interact, and thus the first organic compound 161_1 and the metal or metal compound 161_M easily function as an electron donor with respect to the second organic compound 161_2. Further, the layer 200 of the above structure is less likely to be crystallized than a stacked-layer structure. Thus, when a portion of an organic compound layer including such a layer is processed using a lithography technique, a layer that is less likely to be crystallized even by the influence of oxygen or water in the atmosphere, a chemical solution or water used in a process can be formed. Further, it is possible to prevent an increase in driving voltage or a decrease in current efficiency of a light-emitting element due to crystallization of an intermediate layer or an electron injection layer. Thus, the mixed layer is more suitable than a stacked-layer structure for use as an intermediate layer of a light-emitting element in which a portion of an organic compound layer is processed using a lithography technique.

[0074] In the layer 200, by the interaction of the metal or metal compound 161_M and the first organic compound 161_1, a donor level is formed to function as an electron donor with respect to the second organic compound 161_2, and thus by using the layer 200 as the first layer (161a, 161b) of the intermediate layer (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 (the second layer 162a and the second layer 162b) on the cathode side in the intermediate layer can be easily injected into the first light-emitting unit side. Thus, electron injection into the first light-emitting unit becomes easy, and thus it is possible to reduce the driving voltage of a light-emitting element and to increase the emission efficiency.

[0075] Further, by using the layer 200 as the electron injection layer (115, 115a, 115b), it is possible to reduce the electron injection barrier from the second electrode 102 to the organic compound layer (103a, 103b) and to smoothly inject and transport electrons injected from the second electrode 102 to the light-emitting layer (113a, 113b) side, and thus a light-emitting element with a reduced driving voltage and high emission efficiency can be obtained.

[0076] As the metal or metal compound 161_M, a metal element having a small work function, such as an alkali metal and an alkaline earth metal, a transition metal (a metal element of Group 3 to Group 11), or a metal element of Group 12 to Group 14, or a metal compound thereof can be used.

[0077] Since metals and compounds of metals having a small work function represented by alkali metals and alkaline earth metals and the reactivity of the metals and the compounds with oxygen and water are high, when they are used for light emitting devices processed using a lithography technique, light emitting efficiency can decrease, driving voltage can increase, driving life can decrease, a non-light emitting region can occur at the end of a light emitting portion, and the like, thereby causing a decrease in characteristics or reliability of the light emitting device. However, in one embodiment of the present application, even in the case where alkali metals and alkaline earth metals and compounds thereof are used, the above-described substances are stabilized by interacting with the first organic compound 161_1 and the second organic compound 161_2, and thus a middle layer which is resistant to oxygen and water in the atmosphere and water and a liquid medicine used in a process using a lithography technique can be formed. By using alkali metals and alkaline earth metals and compounds thereof as the metal or the metal compound 161_M, the above-described substances can interact with the first organic compound 161_1 to form a high donor level (SOMO level or HOMO level), and thus it is easy to supply electrons to the second organic compound 161_2. Thus, in the case where such a layer 200 is used as the first layer (161a, 161b) of the middle layer (160a, 160b), an electron injection barrier from the middle layer (160a, 160b) to the first electron transport layer (114a_1, 114b_1) can be decreased and electrons generated in the middle layer 160a can be smoothly injected and transported to the first electron transport layer (114a_1, 114b_1), and thus it is preferable. Further, in the case where such a layer 200 is used as the electron injection layer (115, 115a, 115b), an electron injection barrier from the second electrode 102 to the organic compound layer (103a, 103b) can be decreased and electrons injected from the second electrode 102 can be smoothly injected and transported to the light emitting layer (113a, 113b) side, and thus it is preferable.

[0078] Further, the metal or metal compound 161_M can also use a transition metal (metal elements of Group 3 to Group 11) and metal elements of Group 12 to Group 14 and compounds thereof. The above substances have low reactivity with oxygen in the air and water and a resist used in a process using a lithography technique. Thus, in the case where the above substances are used for a light emitting device, it is possible to have less degradation due to water and oxygen that can occur in the case where a metal with a small work function is used. On the other hand, a transition metal (metal elements of Group 3 to Group 11) and metal elements of Group 12 to Group 14 are stable and have low electron injection properties, and thus there is a problem that it easily leads to a decrease in emission efficiency, an increase in driving voltage, a decrease in driving life, and the like of a light emitting device. However, in one embodiment of the present application, even in the case where a transition metal (metal elements of Group 3 to Group 11) and metal elements of Group 12 to Group 14 are used as the metal or metal compound 161_M, the above substances interact with the first organic compound 161_1 to form a donor level (SOMO level or HOMO level) and can easily supply an electron to a second organic compound having electron transport properties. Thus, in the case where the layer 200 is used as the first layer (161a, 161b) of the intermediate layer (160a, 160b), an electron injection barrier from the intermediate layer (160a, 160b) to the first electron transport layer (114a_1, 114b_1) can be reduced and an electron generated in the intermediate layer 160a is smoothly injected and transported to the first electron transport layer (114a_1, 114b_1). Further, in the case where such a layer 200 is used as the electron injection layer (115, 115a, 115b), an electron injection barrier from the second electrode 102 to the organic compound layer (103a, 103b) can be reduced and an electron injected from the second electrode 102 is smoothly injected and transported to the light emitting layer (113a, 113b) side. Further, a layer having resistance to oxygen and water in the air and water and a resist used in a process using a lithography technique can also be formed, and thus is preferable. Thus, one embodiment of the present application can provide a light emitting device having good moisture resistance, water resistance, oxygen resistance, and chemical resistance, a low driving voltage, and good emission efficiency.

[0079] When the first organic compound 161_1 interacts with the metal or metal compound 161_M, in the case where the sum of the number of electrons of the compound and the number of electrons of the metal is odd, the stable energy can be smaller, and the donor level (SOMO level or HOMO level) formed can be a high level, and thus is preferable. Thus, in the case where the number of electrons of the compound is even, the metal is preferably an odd group in the periodic table.

[0080] As the first organic compound 161_1 and the second organic compound 161_2, a combination of organic compounds that form an exciplex (also referred to as an Exciplex) is preferably selected and used. An exciplex is an excited state formed of two or more substances, and in photoexcitation, an exciplex is formed by interaction of one substance in an excited state and another substance in a ground state. In the case where the first organic compound 161_1 and the second organic compound 161_2 are a combination in which interaction is easy, the first organic compound 161_1 easily functions as an electron donor to the second organic compound 161_2 by interaction with the metal or the metal compound 161_M. That is, by selecting and using a combination of organic compounds that form an exciplex as the first organic compound 161_1 and the second organic compound 161_2, it is possible to easily supply an electron from a donor level formed of the first organic compound 161_1 and the metal or the metal compound 161_M to the second organic compound 161_2.

[0081] The excitation energy level of an exciplex is lower than the singlet excitation energy level (S1 energy level) of one substance and the singlet excitation energy level (S1 energy level) of the other substance that form the exciplex. Thus, in the case where the first organic compound 161_1 and the second organic compound 161_2 are a combination that form an exciplex, the emission spectrum of the exciplex shifts to the longer wavelength side as compared with the emission spectrum of the first organic compound 161_1 and the emission spectrum of the second organic compound 161_2.

[0082] Thus, for example, the peak wavelength of a 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 a PL spectrum of a single film of the first organic compound 161_1 and the peak wavelength of a PL spectrum of a single film of the second organic compound 161_2. In this case, the first organic compound 161_1 and the second organic compound 161_2 can be said to be a combination that form 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 longer than the peak wavelength of the PL spectrum of the single film of the first organic compound 161_1 and the peak wavelength of the PL spectrum of the single film of the second organic compound 161_2 at room temperature, preferably by 20 nm or more, more preferably by 30 nm or more, further preferably by 50 nm or more. Further, when the wavelength is converted into energy, the energy of the peak of the PL spectrum of the mixed film containing the first organic compound 161_1 and the second organic compound 161_2 is lower than the energy of the peak of the PL spectrum of the single film of the first organic compound 161_1 and the energy of the peak of the PL spectrum of the single film of the second organic compound 161_2 at room temperature, preferably by 0.1 eV or more, more preferably by 0.2 eV or more, further preferably by 0.3 eV or more. When the above difference is present, the first organic compound 161_1 and the second organic compound 161_2 can be said to be a combination capable of forming an exciplex more efficiently.

[0084] Note that in the case where a plurality of peak wavelengths are present in the PL spectrum, the peak wavelength of the PL spectrum at the shortest wavelength can be used to compare the peaks of the PL spectrum.

[0085] Alternatively, the wavelength of the emission end on the short-wavelength side of the PL spectrum of the mixed film containing the first organic compound 161_1 and the second organic compound 161_2 is preferably longer than the wavelength of the emission end on the short-wavelength side of the PL spectrum of the first organic compound 161_1 and the wavelength of the emission end on the short-wavelength side 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 can be said to be a combination forming an exciplex.

[0086] More specifically, the wavelength of the emission end on the short wavelength side 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 emission end on the short wavelength side of the PL spectrum of the first organic compound 161_1 and the wavelength of the emission end on the short wavelength side of the PL spectrum of the second organic compound 161_2 at room temperature, preferably by 20 nm or more, more preferably by 30 nm or more, and further preferably by 50 nm or more. In addition, when the wavelengths are converted into energies, the energy of the emission end on the short wavelength side of the PL spectrum of the mixed film containing the first organic compound 161_1 and the second organic compound 161_2 is lower than the energy of the emission end on the short wavelength side of the PL spectrum of the first organic compound 161_1 and the energy of the emission end on the short wavelength side of the PL spectrum of the second organic compound 161_2 at room temperature, preferably by 0.1 eV or more, more preferably by 0.2 eV or more, and further preferably by 0.3 eV or more. When the above difference is present, the first organic compound 161_1 and the second organic compound 161_2 can be said to be a combination capable of forming an exciplex more efficiently.

[0087] Note that the emission end on the short wavelength side of the PL spectrum can be calculated from the intersection of a tangent line drawn at the value of the maximum gradient on the short wavelength side of a peak (or shoulder) observed at the shortest wavelength of the PL spectrum and the horizontal axis or the baseline.

[0088] In addition, by mixing the first organic compound 161_1 and the second organic compound 161_2, the transport property, heat resistance, and solubility of the intermediate layer can be easily adjusted. The weight ratio, the volume ratio, and the molar ratio of the contents of the first organic compound 161_1 and the second organic compound 161_2 can be any of first organic compound 161_1 : second organic compound 161_2 = 1 : 19 to 19 : 1, and preferably 3 : 7 to 7 : 3. Furthermore, the emission spectrum of the exciplex formed from the first organic compound 161_1 and the second organic compound 161_2 can also be the spectrum when they are mixed at first organic compound 161_1 : second organic compound 161_2 = 1 : 1.

[0089] In addition, the peak wavelength of a 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 preferably longer 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 at room temperature. In this case, the first organic compound 161_1 and the second organic compound 161_2 can be said 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 longer than the peak wavelength of the PL spectrum of the single film of the first organic compound 161_1 and the peak wavelength of the PL spectrum of the single film of the second organic compound 161_2 at room temperature, preferably by 20 nm or more, more preferably by 30 nm or more, and further preferably by 50 nm or more. In addition, when the wavelength is converted into energy, the energy of the peak 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 lower than the energy of the peak of the PL spectrum of the single film of the first organic compound 161_1 and the energy of the peak of the PL spectrum of the single film of the second organic compound 161_2 at room temperature, preferably by 0.1 eV or more, more preferably by 0.2 eV or more, and further preferably by 0.3 eV or more. When the above difference is present, the first organic compound 161_1 and the second organic compound 161_2 can be said to be a combination capable of forming an exciplex more efficiently.

[0091] Alternatively, the wavelength of the emission end on the short wavelength side 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 longer than the wavelength of the emission end on the short wavelength side of the PL spectrum of the single film of the first organic compound 161_1 and the wavelength of the emission end on the short wavelength side of the PL spectrum of the single film 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 can be said to be a combination forming an exciplex.

[0092] More specifically, the wavelength of the light emission end on the short wavelength side 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 longer than the wavelength of the light emission end on the short wavelength side of the PL spectrum of the single film of the first organic compound 161_1 and the wavelength of the light emission end on the short wavelength side of the PL spectrum of the single film of the second organic compound 161_2 at room temperature, and the difference is preferably 20 nm or more, more preferably 30 nm or more, and further preferably 50 nm or more. In addition, when the wavelengths are converted into energies, the energy of the light emission end on the short wavelength side 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 lower than the energy of the light emission end on the short wavelength side of the PL spectrum of the single film of the first organic compound 161_1 and the energy of the light emission end on the short wavelength side of the PL spectrum of the single film of the second organic compound 161_2 at room temperature, and the difference is preferably 0.1 eV or more, more preferably 0.2 eV or more, and further preferably 0.3 eV or more. When the above difference is present, the first organic compound 161_1 and the second organic compound 161_2 can be said to be a combination capable of forming an exciplex more efficiently.

[0093] In addition, as the first organic compound 161_1, an organic compound having a LUMO (Lowest Unoccupied Molecular Orbital) level higher than that of the second organic compound 161_2 is preferably used. Thus, the first organic compound 161_1 and the second organic compound 161_2 easily form an exciplex, and it is possible to easily supply an electron from a donor level formed of the first organic compound 161_1 and the metal or metal compound 161_M to the second organic compound 161_2. Further, as the first organic compound 161_1, an organic compound having a LUMO level higher than that of the second organic compound 161_2 by 0.05 eV or more is preferably used. Alternatively, as the first organic compound 161_1, an organic compound having a LUMO level higher than that of the second organic compound 161_2 by 0.1 eV or more, and preferably by 0.2 eV or more is preferably used.

[0094] For example, the LUMO level of the organic compound used as the first organic compound 161 1 is preferably higher than or equal to -3.0 eV and lower than or equal to -2.0 eV, further preferably higher than or equal to -2.7 eV and lower than or equal to -2.0 eV. With this structure, it is easy to supply an electron from the donor level formed by the first organic compound 161 1 and the metal or metal compound 161 M to the second organic compound 161 2. In addition, the LUMO level of the organic compound used as the second organic compound 161 2 is preferably higher than or equal to -3.0 eV and lower than or equal to -2.0 eV, further preferably higher than or equal to -3.0 eV and lower than or equal to -2.5 eV. With this structure, the electron transport property of the second organic compound 161 2 can be improved.

[0095] As the first organic compound 161 1, an organic compound whose HOMO level is higher than that of the second organic compound 161 2 is preferably used. With this structure, the first organic compound 161 1 and the second organic compound 161 2 easily form an exciplex, and it is easy to supply an electron from the donor level formed by the first organic compound 161 1 and the metal or metal compound 161 M to the second organic compound 161 2. In addition, the first organic compound 161 1 is preferably an organic compound whose HOMO level is 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 whose HOMO level is higher than that of the second organic compound 161 2 by 0.1 eV or more, further preferably by 0.2 eV or more.

[0096] Note that the HOMO level and the LUMO level of an organic compound are generally estimated by CV (cyclic voltammetry), photoelectron spectroscopy, optical absorption spectroscopy, inverse photoelectron spectroscopy, or the like. When values of different compounds are compared, values estimated by the same measurement are preferably used for comparison.

[0097] Furthermore, it is preferable to select a combination of 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 composed of two or more substances, formed by the transfer of charge from one substance to another through interaction. When the first organic compound 161_1 and the second organic compound 161_2 are a combination that easily interacts, the first organic compound 161_1 interacts with the metal or metal compound 161_M, making it easy for the second organic compound 161_2 to act as an electron donor. In other words, by selecting a combination of 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 transferred from the donor level formed by the first organic compound 161_1 and the metal or metal compound 161_M to the second organic compound 161_2.

[0098] When a charge-transfer complex is formed, a new absorption band distinct from that of the substance forming the charge-transfer complex is observed. Therefore, for example, 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 preferably longer 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 at room temperature. In this case, the first organic compound 161_1 and the second organic compound 161_2 can be said to form a charge-transfer complex.

[0099] More specifically, the wavelength of the long-wavelength absorption edge of the absorption spectrum of the mixed film comprising the first organic compound 161_1 and the second organic compound 161_2 at room temperature is longer than the wavelengths of the long-wavelength absorption edges of the absorption spectra of the first organic compound 161_1 and the second organic compound 161_2 alone, and the difference between the wavelengths is preferably 30 nm or more, more preferably 50 nm or more, and even more preferably 80 nm or more. Furthermore, when wavelength is converted to energy, the energy of the long-wavelength absorption edge of the absorption spectrum of the mixed film comprising the first organic compound 161_1 and the second organic compound 161_2 at room temperature is lower than the energy of the long-wavelength absorption edge of the absorption spectrum of the first organic compound 161_1 and the second organic compound 161_2 alone, and the difference between the wavelengths is preferably 0.2 eV or more, more preferably 0.3 eV or more, and even more preferably 0.5 eV or more. When having the above-mentioned differences, the first organic compound 161_1 and the second organic compound 161_2 can be said to be a combination that can more efficiently form a charge transfer complex.

[0100] Further, for example, the wavelength 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 longer than the wavelength of the absorption edge on the long wavelength side of the absorption spectrum of the 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 the single film of the second organic compound 161_2 at room temperature. In this case, the metal or metal compound 161_M, the first organic compound 161_1, and the second organic compound 161_2 can be said to be a combination that 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 containing the metal or metal compound 161_M, the first organic compound 161_1, and the second organic compound 161_2 is preferably longer than the wavelength of the absorption edge on the long wavelength side of the absorption spectrum of the 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 the single film of the second organic compound 161_2 at room temperature, preferably by 30 nm or more, more preferably by 50 nm or more, and further preferably by 80 nm or more. Further, when the wavelength is converted into 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 lower than the energy of the absorption edge on the long wavelength side of the absorption spectrum of the 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 the single film of the second organic compound 161_2 at room temperature, preferably by 0.2 eV or more, more preferably by 0.3 eV or more, and further preferably by 0.5 eV or more. When having the above difference, the metal or metal compound 161_M, the first organic compound 161_1, and the second organic compound 161_2 can be said to be a combination that forms a charge transfer complex more efficiently.

[0102] Further, the absorption edge on the long wavelength side of the absorption spectrum can be cut by the maximum of the absolute value of the gradient on the long wavelength side of the peak (or shoulder) observed at the longest wavelength of the absorption spectrum, and the absorption edge on the long wavelength side of the absorption spectrum can be calculated from the intersection of the cut line with the horizontal axis or the baseline.

[0103] Further, 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 can also be the spectrum when the first organic compound 161_1 and the second organic compound 161_2 are mixed at 1:1.

[0104] Further, both the first organic compound 161_1 and the second organic compound 161_2 preferably use an organic compound having electron-transport property. As the organic compound having electron-transport property, for example, an organic compound having a heteroaromatic ring can be given. As the heteroaromatic ring, specifically, a π-electron deficient heteroaromatic ring such as 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, a triazole ring, and the like including a condensed ring thereof is preferably used, because the above heteroaromatic ring is stable in electrochemistry and has high electron-transport property.

[0105] The above heteroaromatic ring is preferred because it easily interacts with the metal or metal compound 161_M due to the inclusion of a nitrogen atom having a non-shared electron pair.

[0106] Further, the first organic compound 161_1 preferably uses an organic compound having an electron-donating group. When an organic compound having an electron-donating group is used as the first organic compound 161_1, the first organic compound 161_1 easily interacts with the metal or metal compound 161_M. Further, it is easy to supply an electron from a donor level formed by the first organic compound 161_1 and the metal or metal compound 161_M to the second organic compound 161_2.

[0107] Details of 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 later.

[0108] <Analysis of interaction between metal or metal compound and organic compound by quantum chemical calculation> Here, the interaction between the metal or metal compound 161_M, the first organic compound 161_1, and the second organic compound 161_2 is analyzed by quantum chemical calculation.

[0109] <Estimation of interaction between metal or metal compound and organic compound> First, the spin density and the electrostatic potential (ESP) 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 were analyzed by quantum chemical calculation. In the calculation, as the metal or metal compound 161_M, a silver atom (Ag) or a lithium atom (Li) was used, as the first organic compound 161_1, 4,7-di-l-pyrrolidinyl-l,10-phenanthroline (abbreviation: Pyrrd-Phen) was used, and as the second organic compound 161_2, 2,9-di(naphthalen-2-yl)-4,7-diphenyl-l,10-phenanthroline (abbreviation: NBPhen) or 2,2'-(2,2'-bipyridine-6,6'-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 6,6'(P-Bqn)2BPy) was used. Note that Pyrrd-Phen and 6,6'(P-Bqn)2BPy are combinations that form an exciplex. The structural formulas of Pyrrd-Phen, NBPhen, and 6,6'(P-Bqn)2BPy are shown below. Note that a position number is attached to the phenanthroline ring in the structural formula of Pyrrd-Phen and NBPhen.

[0110] [Chemical Formula 1]

[0111] As a quantum chemical calculation program, Gaussian09 was used. In the calculation, an SGI8600 manufactured by HPE Corporation was used and the most stable structure in the ground state of each organic compound and the composite material was calculated by a density functional theory method (DFT). As a basis function, 6-311G(d,p) and LanL2DZ were used, and as a functional, B3LYP was used. Note that the total energy of DFT is represented by the sum of potential energy, interelectronic electrostatic energy, kinetic energy of an electron, and exchange correlation energy including all interactions between electrons. In DFT, the exchange correlation interaction is approximated by a functional of an electron density (a function of a function) using a functional of a one-electron potential, and thus the calculation accuracy is high.

[0112] In FIGS. 3A-3CIn the present embodiment, as the metal or metal compound 161_M, Ag is used, as the first organic compound 161_1, Pyrrd-Phen is used, and as the second organic compound 161_2, NBPhen is used, and the analysis results of the spin density distribution in the ground state of the composite material of the first organic compound (Pyrrd-Phen) and the metal or metal compound (Ag), the composite material of the second organic compound (NBPhen) and the metal or metal compound (Ag), and the composite material of the first organic compound (Pyrrd-Phen), the second organic compound (NBPhen), and the metal or metal compound (Ag) are shown. In the drawing, the sphere indicates an atom constituting the compound, and the cloud around the atom indicates the density value in atomic units of 0.003 e / a0 3 (e represents elementary charge (1 e = 1.60218 x 10 -19 C) and a0is the Bohr radius (1 a0= 5.29177 x 10 -11 m)) and indicates the localized state of the doublet ground state of the compound. Note that the ground state of Pyrrd-Phen and the ground state of NBPhen are singlet ground states, and thus the spin density distribution is not observed.

[0113] FIG. 3A The analysis results of the spin density distribution in the ground state of the composite material of the first organic compound (Pyrrd-Phen) and the metal or metal compound (Ag) are shown. In the doublet ground state of the composite material of the first organic compound (Pyrrd-Phen) and the 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) is coordinated to the nitrogen atoms (N) at positions 1 and 10 having non-shared electron pairs in the 1, 10-phenanthroline ring of the first organic compound (Pyrrd-Phen) and is stabilized. Thus, as shown in FIG. 6, it is found that the spin distribution due to the unpaired electron possessed by Ag is present on a part of the 1, 10-phenanthroline ring of Pyrrd-Phen, and in particular, on the nitrogen atoms (N) at positions 1 and 10 having non-shared electron pairs. However, since the interaction is weak, most of the spin density is present on Ag. Hereinafter, the nitrogen atoms (N) at positions 1 and 10 having non-shared electron pairs in the 1, 10-phenanthroline ring are sometimes referred to as N1 and N10. FIG. 3A

[0114] FIG. 3B ​An analysis result of spin density distribution in the ground state of the composite of the second organic compound (NBPhen) and the metal or metal compound (Ag) is shown. 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) is coordinated to N1 and N10 of the second organic compound (NBPhen) to be stabilized. Therefore, as shown in FIG. 3B , it is found that the spin distribution due to the unpaired electron possessed by Ag is partially present in the 1,10-phenanthroline ring of NBPhen, particularly in N1 and N10. However, since the interaction is weak, most of the spin density is present in Ag.

[0115] FIG. 3C An analysis result of spin density distribution in 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) is shown. 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, and the metal or metal compound (Ag) is coordinated to N1 and N10 of the first organic compound (Pyrrd-Phen) and N1 and N10 of the second organic compound (NBPhen) to be stabilized. Therefore, as shown in FIG. 3C , it is found that the spin distribution due to the unpaired electron possessed by Ag is partially present in NBPhen. In addition, no spin density distribution is observed in Ag. It is thus found that NBPhen becomes a radical anion state by the interaction of Pyrrd-Phen, NBPhen, and Ag.

[0116] In FIG. 4 , Li is used as the metal or metal compound 161_M, Pyrrd-Phen is used as the first organic compound 161_1, and 6,6'(P-Bqn)2BPy is used as the second organic compound 161_2, and an analysis result of spin density distribution in the 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) is shown. In the drawing, a sphere indicates an atom constituting a compound, and a cloud around the atom indicates that the isovalue is 0.0004 [electrons / au 3], and shows the local distribution state in the doublet ground state of this 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 double ground state of the composite material 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), the second organic compound (6,6'(P-Bqn)2BPy), and the metal or metal compound (Li) interact with each other, and the metal or metal compound (Li) coordinates to N1 and N10 of the first organic compound (Pyrrd-Phen) and to the nitrogen atom having an unshared electron pair in the pyridine ring and the benzo[h]quinazoline ring of the second organic compound (6,6'(P-Bqn)2BPy), thereby stabilizing the reaction. Therefore, as FIG. 4 As shown, it is known that the spin density of the unpaired electrons in Li is localized in 6,6'(P-Bqn)2BPy. Furthermore, no spin density distribution is observed in Li. Therefore, it is known that the second organic compound (6,6'(P-Bqn)2BPy) is in a radical anion state through the interaction between Pyrrd-Phen, 6,6'(P-Bqn)2BPy, and Li.

[0118] Then, in FIG. 5A 、 FIG. 5B 、 FIG. 6A 、 FIG. 6B and FIG. 6C In the figure, 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 diagram in 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 material of the first organic compound (Pyrrd-Phen) and the metal or metal compound (Ag), the ground state of the composite material of the second organic compound (NBPhen) and the metal or metal compound (Ag), and the ground state of the composite material of the first organic compound (Pyrrd-Phen), the second organic compound (NBPhen) and the metal or metal compound (Ag) are shown respectively. The spheres in the figure represent the atoms constituting the compound, and the clouds around the atoms represent the density value of 0.003e / a in the atomic unit system. 3ESP is the electron density distribution at the time of ESP. ESP is the interaction energy between a positive point charge with unit charge and the electron distribution of a molecule. The electrostatic potential map uses color to represent the ESP in the isoelectronic density surface. In the electrostatic potential map, red and blue are used to represent the area with negative ESP and the area with positive ESP, respectively. Atoms in the area with negative ESP have negative charge, and atoms in the area with positive ESP have positive charge. Note that due to FIG. 5A and FIG. 5B as well as FIGS. 6A-6C Since it is a grayscale image, in order to indicate the area where ESP is negative and the area where ESP is positive, the portion represented by dark red (i.e., the area where ESP is negative) is surrounded by a thick dashed line, and the portion represented by dark blue (i.e., the area where ESP is positive) is surrounded by a thin dotted line.

[0119] FIG. 5A The analysis results of the electrostatic potential map of the first organic compound (Pyrrd-Phen) in the ground state are shown. FIG. 5A It can be seen that the ESP around N1 and N10 is negative in the singlet ground state of the first organic compound (Pyrrd-Phen). Furthermore, in atomic units, the Mulliken partial charge of N1 and N10 is -0.29e, which is negative. Therefore, it can be seen that N1 and N10 have negative partial charges in the singlet ground state of the first organic compound (Pyrrd-Phen).

[0120] FIG. 5B The analysis results of the electrostatic potential map of the second organic compound (NBPhen) in the ground state are shown. FIG. 5B It can be seen that the ESP around N1 and N10 in the singlet ground state of the second organic compound (NBPhen) is negative. Furthermore, in atomic units, the Mulliken partial charge of N1 and N10 is -0.34e, which is negative. Therefore, it can be seen that N1 and N10 have negative partial charges in the singlet ground state of the second organic compound (NBPhen).

[0121] FIG. 6A The results of analyzing the electrostatic potential diagram of the composite material of the first organic compound (Pyrrd-Phen) and the metal or metal compound (Ag) in the ground state are shown. In the double ground state of the composite material of the first organic compound (Pyrrd-Phen) and the metal or metal compound (Ag), the first organic compound (Pyrrd-Phen) 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) to stabilize it. The results show that, as FIG. 6AAs shown, the ESP around N1, N10, Ag of Pyrrd-Phen is negative. In addition, the Mulliken population of N1 and N10 is -0.37e, which is negative, in atomic unit. In addition, the Mulliken population of Ag is -0.18e, which is negative, in atomic unit. Thus, 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, Ag have negative population.

[0122] FIG. 6B The analysis result of the electrostatic potential diagram in the ground state of the composite material of the second organic compound (NBPhen) and the metal or metal compound (Ag) is shown. In the doublet ground state of the composite material 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) is coordinated to N1 and N10 of the second organic compound (NBPhen) to be stabilized. From the result, as shown, FIG. 6B As shown, the ESP around N1, N10, Ag of NBPhen is negative. In addition, the Mulliken population of N1 and N10 is -0.45e and -0.39e, respectively, and the Mulliken population of the metal or metal compound (Ag) is -0.06e, which is negative, in atomic unit. Thus, 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 population.

[0123] FIG. 6C The analysis result of the electrostatic potential diagram in the ground state of the composite material of the first organic compound (Pyrrd-Phen), the second organic compound (NBPhen), and the metal or metal compound (Ag) is shown. In the doublet ground state of the composite material 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, and the metal or metal compound (Ag) is coordinated to N1 and N10 of the first organic compound (Pyrrd-Phen) and N1 and N10 of the second organic compound (NBPhen) to be stabilized. From the result, as shown, FIG. 6CAs shown, the positive ESP is mainly distributed around Ag and Pyrrd-Phen, and the negative ESP is mainly distributed around NBPhen. In addition, it is also known that the ESP around N1 and N10 of NBPhen is negative and the ESP of Ag is positive. In addition, in the atomic unit system, the Mulliken partial charge of N1 and N10 of NBPhen is -0.52e, which is negative, and in contrast, the Mulliken partial charge of Ag is 0.39e, which is positive. Therefore, it is known that the charge distribution of Ag atom is on N1 and N10 of NBPhen.

[0124] Next, in FIG. 7 , Li is used as the metal or metal compound 161_M, Pyrrd-Phen is used as the first organic compound 161_1, and 6,6'(P-Bqn)2BPy is used as the second organic compound 161_2, and the analysis result of the electrostatic potential map of the composite material of the first organic compound (Pyrrd-Phen), the second organic compound (6,6'(P-Bqn)2BPy), and the metal or metal compound (Li) in the ground state is shown. In the drawing, the spherical shape indicates the atom constituting the compound, and the cloud shape around the atom indicates the ESP of the electron density distribution when the isovalue is 0.0004 [electrons / au 3 ] in FIG. 7 , in order to show the region where the ESP is negative and the region where the ESP is positive, the deep red portion (i.e., the region where the ESP is negative) is surrounded by a broken line, and the deep blue portion (i.e., the region where the ESP is positive) is surrounded by a dotted line.

[0125] In the double ground state of the composite material 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), the second organic compound (6,6'(P-Bqn)2BPy), and the metal or metal compound (Li) interact, and the metal or metal compound (Li) is coordinated to N1 and N10 of the first organic compound (Pyrrd-Phen) and the nitrogen atoms having a non-shared electron pair in the pyridine ring and the benzo[h]quinazoline ring of the second organic compound (6,6'(P-Bqn)2BPy) to be stabilized. From the result, it is known that, as FIG. 7As shown, the positive ESP is mainly distributed in Li and Pyrrd-Phen, and the negative ESP is mainly distributed in 6,6'(P-Bqn)2BPy. In addition, the ESP of the nitrogen atom having a non-shared electron pair in the pyridine ring and the benzo[h]quinazoline ring of 6,6'(P-Bqn)2BPy is negative, and the ESP of Li is positive. In addition, the Mulliken partial charge of the Li atom is +0.691 in the atomic unit system.

[0126] Thus, the first organic compound 161_1 interacts with the metal or metal compound 161_M to form an electron donor, and is a combination that functions as an electron donor with respect to the second organic compound 161_2 having electron transport properties. In one embodiment of the present application, by using a composite material of this combination for the intermediate layer, an intermediate layer having good electron injection properties and resistance to oxygen and water in the atmosphere and water and a chemical liquid used in a process using a lithography technique can be formed, and thus a light-emitting element having a reduced driving voltage and high emission efficiency can be obtained.

[0127] <<Estimation of SOMO energy level or stabilization energy>> 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 and the SOMO energy level or HOMO energy level formed at that time were estimated by quantum chemical calculation. Note that in the calculation, as the metal or metal compound 161_M, an atom of silver (Ag), an atom of lithium (Li), an atom of zinc (Zn), an atom of calcium (Ca), an atom of magnesium (Mg), an atom of aluminum (Al), an atom of copper (Cu), or an atom of indium (In) was used, as the first organic compound 161_1, Pyrrd-Phen was used, and as the second organic compound 161_2, 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-pyridinyl)-1,3,5-triazine (abbreviation: 2Py3Tzn) was used. In addition, Pyrrd-Phen and 6,6'(P-Bqn)2BPy are combinations that form an exciplex.

[0128] Here, the following shows the structural formulas of Pyrrd-Phen, mPPhen2P, NBPhen, 6,6'(P-Bqn)2BPy, tPy2P, and 2Py3Tzn. In addition, 6,6'(P-Bqn)2BPy, tPy2P, and 2Py3Tzn have two or more heteroaromatic rings and the two or more heteroaromatic rings are bonded or fused to each other, whereby the organic compound has three or more heteroatoms in total. On the other hand, NBphen has two or more heteroaromatic rings and the two or more heteroaromatic rings are bonded or fused to each other, and the total number of heteroatoms in the organic compound is less than 3.

[0129] [Chemical Formula 2]

[0130] As a quantum chemical calculation program, Gaussian09 was used. The calculation was performed using SGI8600 manufactured by HPE Corporation. First, the ground state of each of the first organic compound 161_1, the second organic compound 161_2, and the metal or metal compound 161_M, and the ground state of 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 were calculated using the density functional theory method (DFT). As a basis function, 6-311G(d, p) and LanL2DZ were used, and as a functional, B3LYP was used. Next, the stabilization energy was calculated from the difference between the total energy of the composite 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. That is, (stabilization energy) = (total energy of the composite 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] Each shows the calculation results of the stabilization energy and the HOMO level or the SOMO level of the composite of the first organic compound 161_1, the second organic compound 161_2, and the metal or metal compound 161_M. Note that the HOMO level and the SOMO level in each table are values calculated by calculation, and sometimes the values are different from the measured values.

[0132] The following table shows the calculation results of the 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. Note that the table also shows the stabilization energy and the HOMO level of the composite material of Zn and Pyrrd-Phen, the stabilization energy and the 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] Stabilization energy (eV) HOMO energy level (eV) Zn + Pyrrd-Phen + mPPhen2P -0.92 -2.43 Zn + Pyrrd-Phen -0.0030 -4.48 Zn + mPPhen2P -0.0012 -5.85 Pyrrd-Phen - -5.65 mPPhen2P - -5.88

[0134] As is clear from the above table, the stabilization energy of the composite material of Zn and Pyrrd-Phen and the stabilization energy of the composite material of Zn and mPPhen2P are negative, and in the case where Zn interacts with Pyrrd-Phen or mPPhen2P, it is more stable in energy than in the case where no interaction occurs. However, the difference is small. In addition, the difference between the HOMO level of the above composite material and the HOMO level of each of Pyrrd-Phen and mPPhen2P is small, and thus it is known that the interaction between Zn and Pyrrd-Phen or mPPhen2P is weak.

[0135] On the other hand, as is clear from the above table, the stabilization energy of the composite material of Zn, Pyrrd-Phen, and mPPhen2P is smaller than the stabilization energy of the composite material of Zn and Pyrrd-Phen and the stabilization energy of the composite material of Zn and mPPhen2P, and is stable in energy. Thus, the stabilization energy of the composite material of the metal or metal compound 161_M, the first organic compound 161_1, and the 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, -4.0 eV or less. In addition, the HOMO level of the composite material of Zn, Pyrrd-Phen, and mPPhen2P is higher than the HOMO level of each of Pyrrd-Phen and mPPhen2P. When the HOMO level is high, the electron injection property is high, and thus it is preferable.

[0136] Next, the following table shows the calculation results of the 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.

[0137] [Table 2] Stabilization energy (eV) HOMO energy level (eV) Ca + Pyrrd-Phen + mPPhen2P -3.3 -2.40 Mg + Pyrrd-Phen + mPPhen2P -2.4 -2.43

[0138] As is apparent from the above table, the stabilization energy of the composite of Ca, Pyrrd-Phen and mPPhen2P is -2.0 eV or less, and the stabilization energy of the composite of Mg, Pyrrd-Phen and mPPhen2P is -2.0 eV or less. Thus, when an alkaline earth metal (Ca, Mg) is used as the metal or metal compound 161_M, the stabilization energy of the composite of the metal or metal compound 161_M, the first organic compound 161_1 and the second organic compound 161_2 can be -2.0 eV or less, and thus is stable in terms of energy, and is therefore preferred. In addition, the HOMO level of the above composite is higher than the HOMO level of each of Pyrrd-Phen and mPPhen2P shown in Table 1. When the HOMO level is high, the electron injection property is high, and thus is preferred.

[0139] Next, the following table shows the calculation results of the composite in which a metal belonging to the odd-numbered group (Group 1, Group 3, Group 5, Group 7, Group 9, Group 11 or Group 13), specifically, Li, Al, Ag, Cu or In is used as the metal or metal compound 161_M, Pyrrd-Phen is used as the first organic compound 161_1, and mPPhen2P is used as the second organic compound 161_2.

[0140] [Table 3] Stabilization energy (eV) SOMO energy level (eV) Li + Pyrrd-Phen + mPPhen2P -3.7 -2.32 Al + Pyrrd-Phen + mPPhen2P -4.1 -2.82 Ag + Pyrrd-Phen + mPPhen2P -1.2 -2.35 Cu + Pyrrd-Phen + mPPhen2P -4.0 -2.39 In + Pyrrd-Phen + mPPhen2P -1.1 -2.83

[0141] As is apparent from the above table, the stabilization energy of the composite of Li, Pyrrd-Phen and mPPhen2P is -3.0 eV or less, the stabilization energy of the composite of Al, Pyrrd-Phen and mPPhen2P is -4.0 eV or less, the stabilization energy of the composite of Ag, Pyrrd-Phen and mPPhen2P is -2.0 eV or less, and the stabilization energy of the composite of Cu, Pyrrd-Phen and mPPhen2P is -1.0 eV or less. Thus, it is apparent that, when a metal belonging to the odd-numbered group, the stabilization energy of the composite of the metal, the first organic compound 161_1 and the second organic compound 161_2 is -1.0 eV or less, -2.0 eV or less, -3.0 eV or less or -4.0 eV or less, and thus is more stable in terms of energy, and is therefore preferred. In addition, the SOMO level of the above composite is higher than the HOMO level of each of Pyrrd-Phen and mPPhen2P shown in Table 1. When the SOMO level is high, the electron injection property is high, and thus is preferred.

[0142] Next, the following table shows the calculation results of the 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. Note that the following table also shows the calculation results of the composite material using Li and Pyrrd-Phen, the calculation results of the composite material using Li and 6,6'(P-Bqn)2BPy, and the calculation results of the composite material using lithium (Li) and NBphen.

[0143] [Table 4] Stabilization energy (eV) SOMO energy level (eV) Li + Pyrrd-Phen + 6,6'(P-Bqn)2BPy -3.79 -2.32 Li + Pyrrd-Phen + NBPhen -3.67 -2.35 Li + Pyrrd-Phen -2.17 -2.46 Li + 6,6'(P-Bqn)2BPy -3.07 -2.88 Li + NBphen -2.31 -2.96

[0144] Further, here, Table 5 shows the LUMO level and the HOMO level of Pyrrd-Phen, 6,6'(P-Bqn)2BPy, tPy2P, 2Py3Tzn, and NBPhen. Note that the HOMO level and the LUMO level in the table are values calculated by calculation, and sometimes the absolute value of the value is different from the absolute value of the measured value.

[0145] [Table 5] LUMO energy level (eV) HOMO energy level (eV) Pyrrd-Phen -1.35 -5.65 6,6'(P-Bqn)2BPy -2.07 -5.99 tPy2P -1.65 -6.37 2Py3Tzn -2.20 -6.89 NBPhen -2.04 -5.74

[0146] As is clear from Table 4, the stabilization energy of the composite material of Li, Pyrrd-Phen, and 6,6'(P-Bqn)2BPy is negative, and the absolute value thereof is large. This state shows that in the case where Pyrrd-Phen, 6,6'(P-Bqn)2BPy, and Li interact with each other, the energy is more stable than in the case where no interaction occurs. Further, as is clear from Table 4 and Table 5, the SOMO level of the composite material is higher than the HOMO level of each of Pyrrd-Phen and 6,6'(P-Bqn)2BPy and the difference from the LUMO level of each is small, and thus the electron injection property is high, and thus the composite material is preferable.

[0147] Further, as is clear from Table 4, the stabilization energy of the composite material of Li, Pyrrd-Phen, and NBphen is negative, and in the case where Pyrrd-Phen, NBphen, and Li interact with each other, the energy is more stable than in the case where no interaction occurs.

[0148] In addition, the SOMO energy level of the composite of Li and 6,6'(P-Bqn)2BPy is low, at -2.88 eV. On the other hand, the SOMO energy level of the composite including Li, 6,6'(P-Bqn)2BPy, and Pyrrd-Phen is higher, at -2.32 eV, and thus the electron injection property thereof is excellent. Furthermore, the stabilization energy of the composite of Li and 6,6'(P-Bqn)2BPy is -3.07 eV, and in comparison, the stabilization energy of the composite of Li, 6,6'(P-Bqn)2BPy, and Pyrrd-Phen is more stable, at -3.79 eV.

[0149] In addition, the SOMO energy level of the composite of Li and NBPhen is low, at -2.96 eV. On the other hand, the SOMO energy level of the composite including Li, NBPhen, and Pyrrd-Phen is high, at -2.35 eV, and thus the electron injection property thereof is excellent. Furthermore, the stabilization energy of the composite of Li and NBPhen is -2.31 eV, and in comparison, the stabilization energy of the composite of Li, NBPhen, and Pyrrd-Phen is more stable, at -3.67 eV.

[0150] Next, the following Table shows the calculation results of the composite of the metal or metal compound 161_M using a metal belonging to Group 11 and Group 13, specifically Ag or In, the first organic compound 161_1 using Pyrrd-Phen, and the second organic compound 161_2 using tPy2P, 2Py3Tzn, or NBPhen.

[0151] [Table 6] Stabilization energy (eV) SOMO energy level (eV) In + Pyrrd-Phen + tPy2P -2.15 -3.03 In + Pyrrd-Phen + NBPhen -1.25 -3.02 Ag + Pyrrd-Phen + 2Py3Tzn -1.79 -2.56 Ag+Pyrrd-Phen+NBPhen -1.26 -2.50

[0152] As is apparent from the above Table, the stabilization energy of the composite of Ag or In, Pyrrd-Phen, and tPy2P, 2Py3Tzn, or NBPhen is negative, and the absolute value thereof is large. Thus, the stabilization energy of the composite of the metal belonging to Group 11 and Group 13, the first organic compound 161_1, and the second organic compound 161_2 is stable, and thus is preferable. Furthermore, the SOMO energy level formed at this time is high and the electron injection property thereof is excellent, and thus is preferable.

[0153] As is apparent from the above calculation results, the composite using the above metal or metal compound 161_M, the first organic compound 161_1, and the second organic compound 161_2 is stable and has a good electron injection property, and thus is suitable for use in the intermediate layer.

[0154] Note that, considering the manufacturing process of the light-emitting device, the organic compound layer of the light-emitting device, particularly the intermediate layer, is deposited by a vacuum evaporation method in many cases. As a material used at this time, a material that can be easily subjected to vacuum evaporation, i.e., a material with a low melting point, is preferably used. Since metals belonging to Group 11 and Group 13 have low melting points, they can be applied to vacuum evaporation. Further, metals belonging to Group 11 and Group 13 are stable against oxygen and water in the air, and are thus preferable. Further, by using a vacuum evaporation method, metal atoms and organic compounds can be mixed easily, and are thus preferable.

[0155] Further, Ag and In can be used as the cathode material. By using the same material for the intermediate layer and the cathode, the light-emitting device can be easily manufactured, and is thus preferable. Further, the manufacturing cost of the light-emitting device can be reduced.

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

[0157] Specifically, a film formed in the same proportions as the intermediate layer of the light-emitting device is prepared, and measurement of the film is performed by mass spectrometry analysis such as 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] According to the results of the mass spectrometry analysis, when the mass number of the first organic compound 161_1 is M1, the mass number of the second organic compound 161_2 is M2, and the mass number of the metal or the metal compound 161_M is M3, positive ions with m / z of M1+M2+M3 or M1+M2+M3+1 can be detected. In addition, when measurement of positive ions is performed by these mass spectrometry analysis methods, ions derived from compounds included in the film, substituents separated from the compounds, compounds from which the substituents are separated, and associated bodies thereof are detected. Thus, for example, when the mass number of a metal separated from a metal compound is 31, positive ions with m / z of M1+M2+31 or M1+M2+31+1 can be detected.

[0159] Next, detailed contents of the 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.

[0160] < Metal or metal compound 161_M > The metal or metal compound 161_M can use a typical metal or a transition metal.

[0161] As the typical metal, an alkali metal (Group 1 element) such as Li, Na, K, Cs, and the like, an alkaline earth metal (Group 2 element) such as Mg, Ca, Ba, and the like, a Group 12 element such as Zn, and the like, an earth metal (Group 13 element) such as Al, In, and the like, a Group 14 element such as Sn, and the like, or a compound thereof can be used.

[0162] When an alkali metal and an alkaline earth metal and a compound thereof are used as the metal or metal compound 161_M, the donor level formed by the interaction with the first organic compound 161_1 can be high in energy, and thus can easily supply an electron to the second organic compound 161_2, whereby the electron generated in the intermediate layer can be smoothly injected and transported to the electron transport layer, and a light-emitting element that emits light with a low driving voltage and at high efficiency can be provided, and thus is preferable.

[0163] As the transition metal, a Group 3 element including Y and lanthanoid elements such as Eu and Yb, a Group 7 element such as Mn, a Group 8 element such as Fe, a Group 9 element such as Co, a Group 10 element such as Ni and Pt, a Group 11 element such as Cu, Ag, and Au, or a compound thereof can be used. The transition metal is low in reactivity with components such as water and oxygen in the air, and thus is preferable.

[0164] Among the above metals, a metal belonging to an odd-numbered group (Group 1, Group 3, Group 5, Group 7, Group 9, Group 11, or Group 13) is more preferable. Among these transition metals belonging to an odd-numbered group, a metal having one electron (unpaired electron) in the outermost shell easily forms SOMO with the first organic compound 161_1, and thus is particularly preferable.

[0165] Further, a metal that is low in melting point and can be deposited by a vacuum evaporation method easily forms a mixed layer with an organic compound, and thus is preferable. Specifically, for example, a metal belonging to a Group 11 element and a Group 13 element is low in melting point, and thus can be applied to vacuum evaporation. Furthermore, a metal belonging to a Group 11 element and a Group 13 element is stable to oxygen and water in the air, and thus is preferable.

[0166] < First organic compound 161_1 > As the first organic compound 161_1, an organic compound having electron-transporting property is preferably used. As the organic compound having electron-transporting property, for example, an organic compound having a heteroaromatic ring can be given. Further, an organic compound having a π-electron deficient heteroaromatic ring is more preferably used, because the π-electron deficient heteroaromatic ring is particularly electrochemically stable and has high electron-transporting property in the heteroaromatic ring. Further, in order that the first organic compound 161_1 interacts with the metal or metal compound 161_M and functions as an electron donor (electron donor) to the second organic compound 161_2, the π-electron deficient heteroaromatic ring preferably has a lone pair, which preferably has electron-donating property. That is, the first organic compound 161_1 preferably includes a basic π-electron deficient heteroaromatic ring. Further, nitrogen has high electronegativity, and thus easily interacts with a metal. Further, since nitrogen can form a conjugated bond in an organic compound, an organic compound having high carrier-transporting property can be realized by using nitrogen for a molecule, particularly for a heteroaromatic ring. Thus, the first organic compound 161_1 preferably has a heteroaromatic ring including nitrogen. Note that the heteroaromatic ring is more preferably an even-numbered ring such as a six-membered ring or an eight-membered ring. By adopting this structure, the lone pair on nitrogen is not involved in conjugation, and thus interaction with the metal or metal compound 161_M is easily caused. Further, in order that an electron is smoothly injected from the intermediate layer and transported to the electron-transporting layer, the first organic compound 161_1 preferably has electron-transporting property. Specifically, for example, the first organic compound 161_1 preferably has a pyridine ring.

[0167] Further, the first organic compound 161_1 is preferably a material in which two or more π-electron deficient heteroaromatic rings are bonded to or fused with each other. Thus, when the metal or metal compound interacts with the first organic compound 161_1 and the second organic compound 161_2 using a bidentate ligand or a polydentate ligand, it becomes stable, and thus an intermediate layer which is not easily deteriorated even by a process using a lithography technique accompanying exposure to the atmosphere can be formed. Thus, even by a process using a lithography technique accompanying exposure to the atmosphere of the EL layer, an electron generated in the intermediate layer can be smoothly injected and transported to an adjacent electron-transporting layer, and thus a tandem light-emitting element in which an increase in driving voltage is suppressed, luminous efficiency is high, and reliability is high can be manufactured by a process using a lithography technique. Specifically, for example, the first organic compound 161_1 preferably has a heteroaromatic ring including two or more pyridine rings. Among them, an organic compound having a bipyridine skeleton is preferable because a nitrogen atom thereof easily coordinates with a metal, and thus easily interacts with the metal or metal compound 161_M.

[0168] Further, the phenanthroline ring is rigid and has high stability, and thus is preferable. In particular, the two nitrogen atoms in the organic compound having a 1,10-phenanthroline ring among phenanthroline rings can coordinate to a metal, and thus easily interact with the metal or the metal compound 161_M, and thus is preferable.

[0169] Further, the first organic compound 161_1 can have a structure in which a plurality of phenanthroline rings are linked by a single bond or a divalent group. As specific examples of the divalent group, for example, an alkylene group, an arylene group, and the like can be given.

[0170] An alkylene group represents a divalent group in which two hydrogen atoms are removed from an alkane. As specific examples of the alkylene group, a divalent group having a structure in which one hydrogen atom is further removed from the specific examples of the above alkyl group can be given.

[0171] An arylene group represents a divalent group in which two hydrogen atoms are removed from an arene. As specific examples, a divalent group having a structure in which one hydrogen atom is further removed from the specific examples of the above aryl group can be given. The arylene group can also have a substituent, and as specific examples of the substituent, an alkyl group, an alkoxy group, a phenyl group, and the like can be given.

[0172] Further, the first organic compound 161_1 preferably has an electron-donating substituent. Thus, the first organic compound 161_1 can have a high HOMO level and a high LUMO level, and thus the difference between the LUMO level of the first organic compound 161_1 and the LUMO level of the second organic compound 161_2 can be increased, and further stabilization can be achieved when the metal or the metal compound 161_M, the first organic compound 161_1, and the second organic compound 161_2 interact, and thus a middle layer which is not easily deteriorated even by a process using a lithography technique accompanying exposure to the atmosphere can be formed. Thus, even by a process using a lithography technique accompanying exposure to the atmosphere of the EL layer, electrons generated in the middle layer can be smoothly injected and transported to an adjacent electron transport layer, and thus a tandem light-emitting element which is suppressed in an increase in driving voltage, has high emission efficiency, and is highly reliable can be manufactured by a process using a lithography technique.

[0173] In particular, the two nitrogen atoms in the organic compound having a 1,10-phenanthroline ring among phenanthroline rings can coordinate to a metal, and thus easily interact with the metal or the metal compound 161_M, and thus is preferable.

[0174] Further, as the first organic compound 161_1, it is more preferable to use an organic compound including a phenanthroline ring having an electron-donating group. In particular, by introducing an electron-donating group to the 1, 10-phenanthroline ring, the electron density of the phenanthroline ring can be increased to improve the efficiency of interaction with the metal or metal compound 161_M. Further, it is preferable to have an electron-donating group at at least one of the 4-position and the 7-position of the 1, 10-phenanthroline ring. By introducing an electron-donating group to the 4-position and the 7-position, the electron density of the nitrogen atoms at the 1-position and the 10-position, which are ortho positions thereof, can be increased. In addition, steric hindrance around the nitrogen atoms at the 1-position and the 10-position can be avoided, and the electron density around the same can be increased. Thus, interaction with the metal or metal compound 161_M can be easily performed, and thus it is preferable.

[0175] Further, when the basicity of the first organic compound 161_1 is high, the hole-transport property of the first layer 161a of the intermediate layer 160a can be significantly reduced by interaction with holes to prevent holes from being transported from the first layer 161a to the second layer 162a, and thus a light-emitting element with high efficiency can be obtained, and thus it is preferable. Specifically, the acidity constant pKa is preferably 8 or more, more preferably 10 or more, and further preferably 12 or more.

[0176] As specific examples of the electron-donating group, an alkyl group, an alkoxy group, an aryloxy group, an alkylamino group, an arylamino group, a heterocyclic amino group, and the like can be given. However, the electron-donating group to be introduced to the phenanthroline ring is not limited thereto. As long as a group capable of increasing the electron density of the phenanthroline ring is introduced to the phenanthroline ring, it can be used as an electron-donating group. Further, the electron-donating group can be introduced to the phenanthroline ring through an arylene group such as a phenylene group, and the arylene group is preferably a para-phenylene group.

[0177] An alkyl group represents a monovalent group in which one hydrogen atom is removed from an alkane (C n H 2n+2 ) group. As specific examples of the alkyl group, 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 the like can be given.

[0178] An alkoxy group represents a monovalent group having a structure in which an alkyl group is bonded to an oxygen atom. As specific examples of the alkoxy group, a methoxy group, an ethoxy group, a n-propoxy group, an i-propoxy group, a n-butoxy group, a sec-butoxy group, an i-butoxy group, a tert-butoxy group, a n-pentoxy group, an i-pentoxy group, a sec-pentoxy group, a tert-pentoxy group, a neopentoxy group, a n-hexoxy group, an i-hexoxy group, a sec-hexoxy group, a tert-hexoxy group, a neohexoxy group, and the like can be given.

[0179] The aryloxy group represents a monovalent group having a structure in which an aryl group is bonded to an oxygen atom. The aryl group represents a monovalent group in which one hydrogen atom is removed from one of the ring-constituting carbon atoms of a monocyclic or polycyclic aromatic compound. As specific examples of the aryloxy group, there can be mentioned a phenoxy group, an o-tolyloxy group, an m-tolyloxy group, a p-tolyloxy group, a mesityloxy group, an o-biphenylyloxy group, an m-biphenylyloxy group, a p-biphenylyloxy group, a 1-naphthoxy group, a 2-naphthoxy group, a 2-fluorenyloxy group, and the like. The aryloxy group can also have a substituent, and as specific examples of the substituent, there can be mentioned an alkyl group, an alkoxy group, a phenyl group, and the like.

[0180] The alkylamino group represents a monovalent group in which one hydrogen atom is removed from the nitrogen atom of a primary or secondary amine in which one or two alkyl groups are bonded to the nitrogen atom. As specific examples of the alkylamino group, there can be mentioned a dimethylamino group, a diethylamino group, and the like.

[0181] The arylamino group represents a monovalent group in which one hydrogen atom is removed from the nitrogen atom of a primary or secondary amine in which one or two aryl groups are bonded to the nitrogen atom. As specific examples of the arylamino group, there can be mentioned a diphenylamino group, a bis (a-naphthyl) amino group, a bis (m-tolyl) amino group, and the like. In addition, the arylamino group can also have a substituent, and as specific examples of the substituent, there can be mentioned an alkyl group, an alkoxy group, a phenyl group, and the like.

[0182] In addition, an amino group having a structure in which both an alkyl group and an aryl group are bonded to the nitrogen atom can be referred to as both an alkylamino group and an arylamino group. As specific examples of such an amino group, there can be mentioned an N-methyl-N-phenylamino group, and the like.

[0183] The heterocyclic amino group represents a monovalent group in which one hydrogen atom is removed from one of the ring-constituting nitrogen atoms of a heterocyclic amine. Note that, here, the heterocyclic amine refers to a monocyclic or polycyclic heterocyclic compound, and represents a compound in which at least one of the ring-constituting atoms is a nitrogen atom to which a hydrogen atom is bonded. As specific examples of the heterocyclic amino group, there can be mentioned groups represented by the following structural formulas (R-1) to (R-27). Note that the heterocyclic amino group can also have a substituent, and as specific examples of the substituent, there can be mentioned an alkyl group, an alkoxy group, a phenyl group, and the like.

[0184] [Chemical Formula 3]

[0185] Note that in the case where the heterocyclic amino group has aromaticity and the non- shared electron pair of the nitrogen atom contributes to the aromaticity, the electron donating property to the phenanthroline ring is sometimes lower than in the case where the non-shared electron pair of the nitrogen atom does not contribute to the aromaticity. Therefore, among the above heterocyclic amino groups, a heterocyclic amino group in which the non-shared electron pair of the nitrogen atom does not contribute to the aromaticity is more preferable. Specifically, a group 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) is more preferable as an electron-donating group. Among them, a group represented by Structural Formula (R-3), (R-4), (R-8), or (R-22) has high electron donating property, and can further increase the electron density of the phenanthroline ring, and is preferable.

[0186] Further, as specific examples of the electron-donating group, a group represented by Structural Formula (R-28) and (R-29) can be given.

[0187] [Chemical Formula 4]

[0188] Note that the organic compound having a phenanthroline ring that can be used as the first organic compound 161_1 can have both the above electron-donating group and a substituent other than the above. In addition, in the case where a phenanthroline ring is introduced to an electron-withdrawing group (cyano group, fluoro group, or the like), the electron density of the phenanthroline ring is sometimes reduced and is not easily interacted with the metal or metal compound 161_M, and thus is not preferable. As specific examples of the substituent other than the above electron-donating group that can be introduced to the phenanthroline ring, an aryl group can also be given. As specific examples of the aryl group, 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 2-fluorenyl group, and the like can be given. The aryl group can also have a substituent, and as specific examples of the substituent, an alkyl group, an alkoxy group, a phenyl group, and the like can be given.

[0189] Further, the first organic compound 161_1 can also have a structure in which a plurality of phenanthroline rings are connected by a single bond or a divalent group. As specific examples of the divalent group, for example, an alkylene group, an arylene group, and the like can be given.

[0190] An alkylene group represents a divalent group in which two hydrogen atoms are removed from an alkane. As specific examples of the alkylene group, a divalent group having a structure in which one hydrogen atom is further removed from the above specific examples of the alkyl group can be given.

[0191] An arylene group represents a divalent group obtained by removing two hydrogen atoms from an aromatic hydrocarbon. As specific examples, a divalent group having a structure obtained by removing one hydrogen atom from the specific examples of the above-described aryl group can be given. The arylene group can also have a substituent, and as specific examples of the substituent, an alkyl group, an alkoxy group, a phenyl group, and the like can be given.

[0192] Specific examples of the organic compound that can be used as the first organic compound 161_1 are represented by Structural Formula (100) to Structural Formula (112). Note that the organic compound that can be used as the first organic compound 161_1 is not limited to these.

[0193] [Chemical Formula 5]

[0194] In addition, Structural Formula (100) represents Pyrrd-Phen, Structural Formula (101) represents 4,7-bis[4-(1-pyrrolidinyl)phenyl]-1,10-phenanthroline (abbreviation: PrdP2Phen), Structural Formula (104) represents 4,7-bis(1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidin-1-yl)-1,10-phenanthroline (abbreviation: 4,7hpp2Phen), Structural Formula (105) represents 4,7-bis(2,3,3a,4,5,6,7,7a-octahydro-1H-isoindol-2-yl)-1,10-phenanthroline (abbreviation: Hid2Phen), Structural Formula (107) represents 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) represents 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) represents 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] Further, when the minimum value of the ESP of the first organic compound 161_1 is small (i.e., negative and large in absolute value), the efficiency of the interaction with the metal or metal compound 161_M is improved, and thus is preferable. In the organic compound having a phenanthroline ring, the ESP around the nitrogen atom of the phenanthroline ring tends to have a negative value, but by introducing an electron-donating group to the phenanthroline ring, the ESP around the nitrogen atom of the phenanthroline ring can be further reduced (the absolute value of the negative value is increased). Note that the ESP refers to the interaction energy of a positive point charge having a unit electric charge and the electron distribution of a molecule. Further, the value of the ESP also varies depending on the threshold value of the electron density. In order to improve the efficiency of the interaction with the metal or metal compound 161_M, the minimum value of the ESP of the first organic compound 161_1 is preferably smaller (larger in the negative direction) than the minimum value of the ESP of the phenanthroline ring having no substituent. Specifically, when the threshold value of the electron density distribution in atomic units is 0.0004 e / a03 3 , the minimum value of the ESP is preferably -0.085 E h , (E h represents the Hartree energy (1 E h = 27.211 eV)), and more preferably -0.090 E h or less. Further, when the threshold value of the electron density distribution is 0.003 e / a03 3 , the minimum value of the ESP is preferably -0.12 E h , and more preferably -0.13 E h or less.

[0196] <<Estimation of Properties by Quantum Chemical Calculation>> The minimum value of the ESP of the organic compound represented by Structural Formulas (100) to (109) was estimated by quantum chemical calculation. Further, for comparison, the minimum value of the ESP of BPhen, mPPhen2P, NBPhen, and Phen was also estimated. The structural formulas of BPhen, mPPhen2P, NBPhen, and Phen are shown below.

[0197] [Chemical Formula 6]

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

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

[0200] [Table 7]

[0201] As can be seen from the table above, in the organic compounds represented by structural formulas (100) to (105), the threshold value of electron density distribution is 0.0004e / a0 3 The minimum ESP value is -0.085E h On the other hand, it is known that the minimum ESP value of the organic compounds represented by the structural formulas (106) to (109) is greater than -0.085E h .

[0202] It is understood that the organic compounds represented by structural formulae (100) to (105) have electron-donating groups at positions 4 and 7 of the 1,10-phenanthroline ring and therefore have the most preferred values.

[0203] The organic compound represented by structural formula (106) has electron-donating groups at the 4- and 7-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. Therefore, compared to groups in which the unshared electron pair of the nitrogen atom does not contribute to aromaticity, the electron-donating capacity to the phenanthroline ring is reduced. Consequently, the minimum ESP value is less likely to decrease, leading to the above-mentioned 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 properties of the nitrogen at the 1- and 10-positions of the 1,10-phenanthroline ring are lower than when the electron-donating groups are introduced at the 4- and 7-positions. Therefore, the substitution positions of the electron-donating groups in the 1,10-phenanthroline ring are preferably the 4- and 7-positions.

[0205] Furthermore, when the first organic compound 161_1 has high basicity, the interaction with holes significantly reduces the hole-transporting property of the first layer 161a of the intermediate layer 160a, thereby preventing holes from being transported from the first layer 161a to the second layer 162a. This is preferred because a highly efficient light-emitting device can be obtained. Specifically, the first organic compound 161_1 preferably has a pKa of 8 or greater, more preferably 10 or greater, and even more preferably 12 or greater.

[0206] When the acidity coefficient pKa of an organic compound is unknown, the acidity coefficient pKa of each skeleton of the organic compound can be investigated, and the largest acidity coefficient pKa among them can be regarded as the acidity coefficient pKa of the organic compound.

[0207] Alternatively, the acidity coefficient can be obtained by calculation. For example, the acidity coefficient pKa can be obtained by the following calculation method.

[0208] As the initial structure of the molecular structure of each molecule used as a calculation model, the most stable structure (singlet ground state) obtained by first-principles calculation was adopted.

[0209] As the first principles calculation above, use The most stable structure in the singlet ground state was calculated using density functional theory (DFT) using Jaguar, a quantum chemical calculation software produced by Inc. 6-31G** was used as the basis function and B3LYP-D3 as the functional function. Maestro GUI manufactured by Inc. performs conformational analysis and sampling using Mixed torsional / Low-mode sampling.

[0210] In the pKa calculation, one or more atoms in each molecule were designated as basic sites. The Macro Model was used to explore the stable structure of the protonated molecule in water. The lowest-energy conformer obtained through conformational exploration using the OPLS2005 force field was used. The Jaguar pKa calculation module was used to optimize the structure using B3LYP / 6-31G*. Single-point calculations were then performed using cc-pVTZ(+). The pKa value was calculated using empirical corrections for functional groups. For molecules with one or more atoms designated as basic sites, the largest value obtained was used as the pKa value. The resulting pKa values ​​are shown.

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

[0212] <Second organic compound 161_2> As the second organic compound 161_2, an organic compound having electron transportability is preferably used. As the organic compound having electron transportability, an organic compound having an electron mobility of 1 x 10 -7 cm 2 / Vs or more when the square root of the electric field strength [V / cm] is 600 is more preferably used. Furthermore, an organic compound having an electron mobility of 1 x 10 -6 cm 2 / Vs or more is more preferably used. In addition, an organic compound other than the above can be used as long as the electron transportability is higher than the hole transportability.

[0213] In addition, as the organic compound having electron transportability, an organic compound having a π-electron deficient heteroaromatic ring is preferably used. As the π-electron deficient heteroaromatic ring, 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 the like are preferably used, and among them, a diazine ring (pyrazine ring, pyrimidine ring, pyridazine ring) or a triazine ring is stable in electrochemistry and has high electron transportability, and thus is preferable.

[0214] As an example of the organic compound which can be used as the second organic compound 161_2, an organic compound represented by the following general formula (G1-1) can be given.

[0215] [Chemical Formula 7]

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

[0217] The organic compound represented by General Formula (G1-1) has a conjugated double bond in which N on each heteroaromatic ring is arranged in the order of N-C-C-N, and has a function of interacting with a metal as a tridentate or more ligand. The organic compound having such a structure easily interacts with a metal, and thus can be suitably used as the second organic compound 161_2.

[0218] In General Formula (G1-1) described above, as the substituted or unsubstituted heteroaromatic ring represented by A 1 , A 2 , and A 3 having 1 to 30 carbon atoms, for example, a heteroaromatic ring having a pyridine skeleton (a pyridine ring, a quinoline ring, an isoquinoline ring, a naphthylidine ring, a bipyridine ring, a phenanthridine ring, a phenanthroline ring, an anthyridine ring, an azaphenanthrene ring), a heteroaromatic ring having a diazine skeleton (a pyrazine ring, a pyrimidine ring, a pyridazine ring, a quinoxaline ring, a benzoquinoxaline ring, a dibenzoquinoxaline ring, a quinazoline ring, a benzoquinazoline ring, a phthalazine ring, a cinnoline ring, a pteridine ring, a phenoxazine ring), a heteroaromatic ring having a triazine skeleton, a heteroaromatic ring having an oxazole skeleton (an imidazole ring, a benzimidazole ring, a pyrazole ring, an oxazole ring, a thiazole ring, a triazole ring, an oxadiazole ring, a thiadiazole ring), and the like can be given. Note that the substituted or unsubstituted heteroaromatic ring represented by A 1 , A 2 , and A 3 having 1 to 30 carbon atoms is not limited thereto. A 1 , A 2 , and A 3 may also form a fused ring with each other. For example, A 1 and A 2 may also bond to each other to form a phenanthroline ring.

[0219] In addition, as an example of the organic compound which can be used as the second organic compound 161_2, an organic compound represented by General Formula (G2-1) below can be given.

[0220] [Chemical Formula 8]

[0221] In General Formula (G2-1), X 1 to X 6 independently represent carbon (C) or nitrogen (N), 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, and R 1 to R 4respectively, independently represent 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. Alternatively, in General Formula (G2-1), X 1 to X 6 may also be bonded directly to each other or via a divalent group to form a condensed ring. Specific examples of the divalent group include, for example, an alkylene group, an arylene group, and the like.

[0222] As the organic compound represented by General Formula (G2-1), the organic compound having a function of interacting with a metal as a tridentate or more ligand is more preferably one including at least one of a heteroaromatic ring having a pyridine skeleton, a heteroaromatic ring having a diazine skeleton, and a heteroaromatic ring having a triazine skeleton. These rings have excellent electrochemical stability, and thus a light-emitting device with good reliability can be provided. In addition, since the electron-transport property is excellent, a light-emitting device with a reduced driving voltage can be provided.

[0223] In addition, as an example of the organic compound that can be used as the second organic compound 161_2, an organic compound represented by General Formula (G3-1) below can be given.

[0224] [Chemical Formula 9]

[0225] In General Formula (G3-1), X 1 to X 4 respectively, independently represent 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. Alternatively, in General Formula (G2-1), X 1 to R 6 respectively, independently represent 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. Alternatively, in General Formula (G2-1), X

[0226] In addition, as an example of the organic compound that can be used as the second organic compound 161_2, an organic compound represented by General Formula (G4-1) below can be given.

[0227] [Chemical Formula 10]

[0228] In General Formula (G4-1), X 1 to X5 respectively independently represent carbon (C) or nitrogen (N), 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 or more and 30 or less carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 or more and 30 or less carbon atoms, R 1 to R 6 respectively independently represent 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 or more and 30 or less carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 or more and 30 or less carbon atoms.

[0229] The organic compound having a pyridine skeleton has a high LUMO energy level, and is therefore preferable. For example, when at least one of X 1 and X 2 represents carbon, the organic compound has a high LUMO energy level due to the pyridine skeleton, and thus can form a composite material having a high SOMO energy level upon interaction with a metal. In other words, the organic compound having a pyridine ring and having a function of interacting as a tridentate or more ligand can form an intermediate layer having a high electron injection property by interacting with a metal.

[0230] In addition, the organic compound having a diazine skeleton or a triazine skeleton is electrochemically stable and has a high electron transport property, and is therefore preferable. For example, when at least one of X 1 and X 2 in General Formulae (G2-1), (G3-1), and (G4-1) represents nitrogen, the organic compound is electrochemically stable and has a high electron transport property due to the diazine skeleton or the triazine skeleton, and thus can form a stable and high electron transport property composite material upon interaction with a metal. In other words, the organic compound having a diazine ring or a triazine ring and having a function of interacting as a tridentate or more ligand can form a high reliability intermediate layer by interacting with a metal.

[0231] In addition, as an example of the organic compound that can be used as the second organic compound 161_2, an organic compound represented by General Formula (G1-2) below can be given.

[0232] [Chemical Formula 11]

[0233] In General Formula (G1-2) above, A 1 and A 2 respectively independently represent a substituted or unsubstituted heteroaryl ring having 1 or more and 30 or less carbon atoms, A 1 and A 2may also form a fused ring with each other, A 1 includes two or more nitrogen atoms.

[0234] The organic compound represented by General Formula (G1-2) has a conjugated double bond in which N on a heteroaromatic ring is arranged in the order of N-C-C-N, and has a function of interacting with a metal as a bidentate or more ligand. The organic compound having such a structure easily interacts with a metal, and thus can be suitably used for the intermediate layer.

[0235] In General Formula (G1-2) described above, as the substituted or unsubstituted heteroaromatic ring having 1 or more and 30 or less carbon atoms represented by A 1 represented by A 2 represented by A 1 and A 2 represented by A 1 and A 2 may also form a fused ring with each other, A 1 and A 2 may also bond to each other to form a pyrazinoquinoxaline ring.

[0236] In addition, as examples of the organic compound that can be used as the second organic compound 161_2, an organic compound represented by General Formula (G2-2) below can be given.

[0237] [Chemical Formula 12]

[0238] In General Formula (G2-2), X 1 to X 4At least one of them represents nitrogen (N), and the others 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, and R 1 to 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. Alternatively, in the general formula (G2-2), X 1 To X 4 They may be bonded to each other directly or through a divalent group to form a condensed ring. Specific examples of the divalent group include an alkylene group and an arylene group.

[0239] As represented by the general formula (G2-2), the organic compound having a function of interacting with a metal as a bidentate or higher ligand preferably includes a heteroaromatic ring having a diazine skeleton or a heteroaromatic ring having a triazine skeleton. These rings have excellent electrochemical stability, so a light-emitting device with good reliability can be provided. In addition, due to the excellent electron transport properties, a light-emitting device with a reduced driving voltage can be provided.

[0240] Examples of organic compounds that can be used as the second organic compound 161_2 include organic compounds represented by the following general formula (G3-2).

[0241] [Chemical Formula 13]

[0242] In the general formula (G3-2), X 1 and X 2 One of the 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, and R 1 to 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] Further, as examples of the organic compound which can be used as the second organic compound 161_2, an organic compound represented by General Formula (G4-2) below can be given.

[0244] [Chemical Formula 14]

[0245] In General Formula (G4-2), X 1 to X 3 at least one of which represents nitrogen (N), and the rest each independently represents carbon (C) or nitrogen (N), 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 or more and 30 or less carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 or more and 30 or less carbon atoms, and R 1 to 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 or more and 30 or less carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 or more and 30 or less carbon atoms.

[0246] An organic compound having a pyridine skeleton has a high LUMO level, and is therefore preferable. For example, when at least one of X 1 and X 2 in General Formulae (G2-2) and (G4-2) and X 1 in General Formula (G3-2) represents carbon, the organic compound has a high LUMO level due to the pyridine skeleton, and thus can form a composite material having a high SOMO level when interacting with a metal. In other words, an organic compound having a pyridine ring and having a function of interacting as a bidentate or more ligand can form an intermediate layer having a high electron injection property by interacting with a metal.

[0247] Further, an organic compound having a diazine skeleton or a triazine skeleton is electrochemically stable and has a high electron transport property, and is therefore preferable. For example, when at least one of X 1 and X 2 in General Formulae (G2-2) and (G4-2) and X 1 in General Formula (G3-2) represents nitrogen, the organic compound is electrochemically stable and has a high electron transport property due to the diazine skeleton or the triazine skeleton, and thus can form a composite material which is stable and has a high electron transport property when interacting with a metal. In other words, an organic compound having a diazine ring or a triazine ring and having a function of interacting as a bidentate or more ligand can form an intermediate layer which is highly reliable by interacting with a metal.

[0248] The following more specific examples of the organic compounds which can be used as the second organic compound 161_2 and the organic compounds represented by General Formula (G1-1) to General Formula (G4-2) are shown by General Formula (250) to General Formula (268).

[0249] [Chemical Formula 15]

[0250] [Chemical Formula 16]

[0251] In General Formula (250) to General Formula (268), R 11 to R 162 independently represent 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 or more and 30 or less carbon atoms, or a substituted or unsubstituted heteroaryl group having 1 or more and 30 or less carbon atoms.

[0252] In addition, as the substituents which can be used in General Formula (G1-1) to General Formula (G4-2) and General Formula (250) to General Formula (268), an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylene group having 6 to 30 carbon atoms, and a heteroaryl group having 1 to 30 carbon atoms can be given. Note that part or all of hydrogen can be deuterium. In addition, the groups which can be used in the above general formulae are not limited to the following specific examples.

[0253] As specific examples of the alkyl group having 1 to 10 carbon atoms, 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, a 1-ethylhexyl group, and the like can be given.

[0254] As specific examples of the cycloalkyl group having 3 to 10 carbon atoms, 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, an adamantyl group, and the like can be given.

[0255] As specific examples of the aryl group having 6 to 30 carbon atoms, there can be mentioned phenyl, o-tolyl, m-tolyl, p-tolyl, mesityl, o-biphenyl, m-biphenyl, p-biphenyl, 1-naphthyl, 2-naphthyl, fluorenyl, 9,9-dimethylfluorenyl, spirobifluorenyl, phenanthryl, anthryl, fluoranthenyl, and the like. In the case where the aryl group having 6 to 30 carbon atoms has a substituent, as the substituent, there can be mentioned an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, phenyl, and the like.

[0256] As specific examples of the arylene group having 6 to 30 carbon atoms, there can be mentioned phenylene, biphenyl-diyl, naphthalene-diyl, fluorene-diyl, acenaphthene-diyl, anthracene-diyl, phenanthrene-diyl, terphenyl-diyl, triphenylene-diyl, phenanthrene-diyl, naphthacene-diyl, benzanthracene-diyl, pyrene-diyl, spirobifluorene-diyl, and the like. In the case where the arylene group having 6 to 30 carbon atoms has a substituent, as the substituent, there can be mentioned an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, phenyl, and the like.

[0257] The heteroaryl group having 1 to 30 carbon atoms means a monovalent group in which one hydrogen atom is removed from one of the ring-forming carbon atoms of a monocyclic or polycyclic heterocyclic aromatic compound having 1 to 30 carbon atoms. As specific examples of the heteroaryl group having 1 to 30 carbon atoms, there can be mentioned 1,3,5-triazin-2-yl, 1,2,4-triazin-3-yl, pyrimidin-4-yl, pyrazin-2-yl, 2-pyridyl, 3-pyridyl, 4-pyridyl, carbazolyl, dibenzofuranyl, dibenzothiophenyl, benzonaphthofuranyl, benzonaphthothiophenyl, indolocarbazolyl, benzofuranocarbazolyl, benzothiophenocarbazolyl, indenocarbazolyl, dibenzocarbazolyl, and the like. In the case where the heteroaryl group has a substituent, as the substituent, there can be mentioned an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, phenyl, and the like.

[0258] The following shows specific examples of the organic compound which can be used as the second organic compound 161_2 and the organic compound represented by General Formula (G1-1) to General Formula (G4-2).

[0259] [Chemical Formula 17]

[0260] [Chemical Formula 18]

[0261] [Chemical Formula 19]

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

[0263] As an organic compound having electron-transporting properties, specifically, 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 3-(4-biphenyl)-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]-9H-carbazole (abbreviation: CO11), 2,2',2"-(1,3,5-benzinetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophene-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOs), and the like organic compounds having an oxazole skeleton, 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy), 1,3,5-tris[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), bathophenanthroline (abbreviation: BPhen), bathocuproin (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]imidazol-2-yl]phenyl)-1,10-phenanthroline (abbreviation: DBimiBphen), and the like organic compounds including a heteroaromatic ring having a pyridine skeleton, 2-[3-(dibenzothiophene-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophene-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-III), 7-[3-(dibenzothiophene-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDBTPDBq-II), 6-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-2,2-dimethylpyrimidine (abbreviation: 2mCzPPy-II), 6-[4-(9-phenyl-9H-carbazol-3-yl)-3,6-dimethylpyrimidine (abbreviation: 2mCzPPy-III), and the like organic compounds including a heteroaromatic ring having a quinoxaline skeleton,h] quinoxaline (abbreviation: 7mDBTPDBq-II) and 6-[3-(dibenzo-thiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 9-[3'-(dibenzo-thiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9mDBtBPNfpr), 9-[3'-(dibenzo-thiophen-4-yl)biphenyl-4-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9pmDBtBPNfpr), 4,6-bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(dibenzo-thiophen-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: 4,6mCzBP2Pm), 8-(biphenyl-4-yl)-4-[3-(dibenzo-thiophen-4-yl)phenyl]-[1]benzo-furo[3,2-d]pyrimidine (abbreviation: 8BP-4mDBtPBfpm), 8-(1,1':4',1"-terphenyl-3-yl)-4-[3-(dibenzo-thiophen-4-yl)phenyl]-[1]benzo-furo[3,2-d]pyrimidine (abbreviation: 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-(dibenzo-thiophen-4-yl-1,2,3,6,7,8,9-d7)phenyl-2,4,6-d3]-[1]benzo-furo[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm-d, 23), 3,8-bis[3-(dibenzo-thiophen-4-yl)phenyl]benzo-furo[2,3-b]pyrazine (abbreviation: 3,8mDBtP2Bfpr), 4,8-bis[3-(dibenzo-thiophen-4-yl)phenyl]-[1]benzo-furo[3,2-d]pyrimidine (abbreviation: 4,8mDBtP2Bfpm), 8-[3'-(dibenzo-thiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[3,2-d]pyrimidine (abbreviation: 8mDBtBPNfpm), 8-[(2,2'-binaphthalenyl)-6-yl]-4-[3-(dibenzo-thiophen-4-yl)phenyl]-[1]benzo-furo[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(NP-PPm)2Py), 6-(biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm), 2,6-bis(4-naphthalen-1-ylphenyl)-4-[4-(3-pyridyl)phenyl]pyrimidine (abbreviation: 2,4NP-6PyPPm), 4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenyl-6-(biphenyl-4-yl)pyrimidine (abbreviation: 6BP-4Cz2PPm), 7-[4-(9-phenyl-9H-carbazol-2-yl)quinazoline-2-yl]-7H-dibenzo[c,g]carbazole (abbreviation: PC-cgDBCzQz), and the like organic compounds having a triazine skeleton, 2-(biphenyl-4-yl)-4-phenyl-6-(9,9'-spirobi[9H-fluorene]-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-6-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn-02), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bis-9H-carbazole (abbreviation: mPCCzPTzn-02), 2-[3'-(9,9-dimethyl-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-(dibenzo-thiophen-4-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mDBtBPTzn), 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviation: TmPPPyTz), 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthryl)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)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), 2-(biphenyl-3-yl)-4-phenyl-6-{8-[(1,1':4',1"-terphenyl)-4-yl]-1-dibenzofuranyl}-1,3,5-triazine (abbreviation: mBP-TPDBfTzn), and the like organic compounds having a triazine skeleton.

[0264] Among the above organic compounds, more preferable are organic compounds having a phenanthroline ring, particularly organic compounds having a 1,10-phenanthroline ring, such as BPhen, BCP, NBPhen, and mPPhen2P, because two nitrogen atoms contained therein can coordinate with a metal, thus easily interacting with the metal. In addition, organic compounds having a dimer structure of a phenanthroline ring, such as mPPhen2P, are more preferable because of their high stability.

[0265] In addition, the number of carbon atoms of the organic compound which can be used as the second organic compound 161_2 is preferably 25 or more and 100 or less. When having the above number of carbon atoms, an organic compound having good sublimability can be realized, and thus thermal decomposition of the organic compound in vacuum deposition can be suppressed, and thus a good material usage efficiency can be obtained. In addition, an organic compound having a glass transition temperature (Tg) of 50 °C or higher and 300 °C or lower can be used. g) is an organic compound having a Tg of 100°C or higher. By this, the intermediate layer can be less likely to be crystallized. By this, when a part of the organic compound layer is processed by a lithography technique, a layer which is less likely to be crystallized even by the influence of oxygen or water in the atmosphere, or a liquid medicine or water used in the process can be formed. By this, the increase in driving voltage or the decrease in current efficiency of the light emitting device due to crystallization of the intermediate layer can be prevented. By this, by using the T g As the second organic compound 161_2, an organic compound having a Tg of 100°C or higher can be used for the intermediate layer of the light emitting device processed by a part of the organic compound layer by a lithography technique.

[0266] As the second organic compound 161_2, an organic compound having a Tg of 100°C or higher can be used for the intermediate layer of the light emitting device processed by a part of the organic compound layer by a lithography technique. g As the second organic compound 161_2, an organic compound having a Tg of 100°C or higher can be used for the intermediate layer of the light emitting device processed by a part of the organic compound layer by a lithography technique. g : 165°C), 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(phenanthrolin-5-yl)dibenzofuran (abbreviation: 2,8Phen2DBf) (T g : 210°C), 5,5',5"-(benzene-1,3,5-triyl)tris-1,10-phenanthroline (abbreviation: Phen3P) (T g : 257°C), and the like. For example, using a differential scanning calorimeter (DSC8500 manufactured by PerkinElmer, Japan Co., Ltd.), and by placing a powder on an aluminum cell and raising the temperature at 40°C / min, the T g .

[0267] In addition, as the second organic compound 161_2, an organic compound having an acidity coefficient pKa of 4 or higher and lower than 8 can be used. By this, the hole-transport property of the second organic compound 161_2 can be reduced, and the hole-transport property of the first layer 161a in the intermediate layer 160a can be reduced, and by this, the light emitting device can be prevented from transmitting holes from the first layer 161a to the second layer 162a, and a light emitting device with high efficiency can be obtained, and thus is preferable. In addition, when the acidity coefficient pKa is too high, the water solubility is improved, and sometimes the resistance to water and liquid medicine used in the process by a lithography technique is reduced. Therefore, the acidity coefficient pKa of the second organic compound 161_2 is preferably 4 or higher and lower than 8.

[0268] In a layer containing a combination of the metal or metal compound 161_M, the first organic compound 161_1, and the second organic compound 161_2, the materials interact more efficiently with each other than in a layer containing only two of the above-described materials (e.g., a layer containing the metal or metal compound 161_M and the first organic compound 161_1 or a layer containing the metal or metal compound 161_M and the second organic compound 161_2). This can be confirmed by a method in which a metal of an odd-numbered group is used for the metal or metal compound 161_M and the spin density of a film containing each material is measured by electron spin resonance (ESR: Electron spin resonance).

[0269] For example, in a case where the spin density of a film containing a metal, the first organic compound 161_1, and the second organic compound 161_2 measured by ESR is higher than the spin density of a film containing a metal and the first organic compound 161_1 measured by ESR or the spin density of a film containing a metal and the second organic compound 161_2 measured by ESR, it is confirmed that, in a layer containing a combination of a metal, the first organic compound 161_1, and the second organic compound 161_2, the materials interact more efficiently with each other than in a layer containing only two of the above-described combination. In addition, it is preferable that the measurement of the spin density by electron spin resonance be performed at room temperature.

[0270] More specifically, the spin density of a film containing a metal and the first organic compound 161_1, which is a signal observed near a g value of 2.00 by electron spin resonance, is 2 x 10 16 spins / cm 3 The spin density of a mixed film containing a metal and the second organic compound 161_2, which is a signal observed near a g value of 2.00 by electron spin resonance, is 2 x 10 16 spins / cm 3 The spin density of a mixed film containing the first organic compound 161_1 and the second organic compound 161_2, which is a signal observed near a g value of 2.00 by electron spin resonance, is 2 x 10 16 spins / cm 3 In a case where the spin density of a mixed film containing a metal, the first organic compound 161_1, and the second organic compound 161_2, which is a signal observed near a g value of 2.00 by electron spin resonance, is 5 x 10 16 spins / cm 3 More preferably, the above is 1 x 10 17 spins / cm 3By doing so, it is possible to confirm the fact that, in a layer containing a combination of a metal, a first organic compound 161_1, and a second organic compound 161_2, interaction between materials occurs more efficiently than in a layer containing only two materials from among the above combination.

[0271] Further, as the ratio of the metal, the molar ratio with respect to the total of the first organic compound 161_1 and the second organic compound 161_2 is preferably 0.1 or more and 10 or less, more preferably 0.2 or more and 5 or less, and further preferably 0.5 or more and 2 or less. Alternatively, the volume ratio is preferably 0.01 or more and 0.3 or less, more preferably 0.02 or more and 0.2 or less, and further preferably 0.05 or more and 0.1 or less. By mixing the metal, the first organic compound 161_1, and the second organic compound 161_2 at the above ratio, it is possible to provide an intermediate layer having good electron injection properties. Further, as the ratio of the first organic compound 161_1, the volume ratio with respect to the second organic compound 161_2 is preferably 0.1 or more and 10 or less, more preferably 0.2 or more and 5 or less, and further preferably 0.5 or more and 2 or less. By mixing the first organic compound 161_1 and the second organic compound 161_2 at the above ratio, it is possible to provide an intermediate layer having good electron transport properties.

[0272] Further, the thickness of the first layer 161a on the anode side in the intermediate layer 160a is preferably 3 nm or more and 20 nm or less, and more preferably 5 nm or more and 10 nm or less. By doing so, it is possible to cause the composite material of the mixed metal, the first organic compound 161_1, and the second organic compound 161_2 to function well, and to provide a light-emitting device having good emission efficiency.

[0273] Next, the structure of the second layer and the third layer that is preferable when the layer 200 is used as the first layer in the intermediate layer will be described.

[0274] [Second Layer] As the second layer of the intermediate layer, a layer containing a third organic compound and a fourth organic compound is preferably used. By doing so, it is possible to inject holes into the upper light-emitting layer well, and thus it is preferable.

[0275] [Third Organic Compound] The third organic compound preferably uses 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, arenes, high molecular compounds (oligomers, dendrimers, polymers, and the like), and the like can be used. As the organic compound having hole transport properties, an organic compound having a hole mobility of 1 x 10 -6 cm 2organic compound having a hole-transporting property is preferably a compound containing a fused aromatic hydrocarbon ring or a π-electron rich heteroaromatic ring. As the fused aromatic hydrocarbon ring, an anthracene ring, a naphthalene ring, or the like is preferable. Further, as the π-electron rich heteroaromatic ring, a fused aromatic ring having at least one of a pyrrole skeleton, a furan skeleton, and a thiophene skeleton is preferable, and specifically a carbazole ring, a dibenzothiophene ring, or a ring in which these rings are further fused with an aromatic ring or a heteroaromatic ring is preferable.

[0276] Such an organic compound having a hole-transporting property more preferably has at least one of a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton. In particular, it can also be an aromatic amine having a substituent including a dibenzofuran ring or a dibenzothiophene ring, an aromatic monoamine including a naphthalene ring, or an aromatic monoamine in which a 9-fluorenyl group is bonded to the nitrogen of an amine through an arylene group. Note that when such an organic compound having a hole-transporting property is a substance including an N,N-bis(4-biphenyl)amino group, a long-life light-emitting element can be manufactured, and is therefore preferable.

[0277] As the organic compound having a hole-transporting property described above, specifically, 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)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(ll)(4)), N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP), N-[4-(dibenzothiophene-4-yl)phenyl]-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: BBAαNβNB-03), 4,4'-diphenyl-4"-(7-phenyl)naphthyl-2-yltriphenylamine (abbreviation: BBAPβNB-03), 4,4'-diphenyl-4"-(6;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B), 4,4'-diphenyl-4"-(7;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B-03), 4,4'-diphenyl-4"-(4;2'-binaphthyl-1-yl)triphenylamine (abbreviation: BBAβNαNB), 4,4'-diphenyl-4"-(5;2'-binaphthyl-1-yl)triphenylamine (abbreviation: BBAβNαNB-02), 4-(4-biphenyl)-4'-(2-naphthyl)-4"-phenyltriphenylamine (abbreviation: TPBiAβNB), 4-(3-biphenyl)-4'-[4-(2-naphthyl)phenyl]-4"-phenyltriphenylamine (abbreviation: mTPBiAβNBi), 4-(4-biphenyl)-4'-[4-(2-naphthyl)phenyl]-4"-phenyltriphenylamine (abbreviation: TPBiAβNBi), 4-phenyl-4'-(1-naphthyl)triphenylamine (abbreviation: αNBA1BP), 4,4'-bis(1-naphthyl)triphenylamine (abbreviation: αNBB1BP), 4,4'-diphenyl-4" -[4' - (carbazol-9-yl) biphenyl-4-yl] triphenylamine (abbreviation: YGTBi1BP), 4'-[4-(3-phenyl-9H-carbazol-9-yl) phenyl] tri(biphenyl-4-yl) amine (abbreviation: YGTBi1BP-02), 4-[4'-(carbazol-9-yl) biphenyl-4-yl]-4'-(2-naphthyl)-4"-phenyl triphenylamine (abbreviation: YGTBiβNB), N-[4-(9-phenyl-9H-carbazol-3-yl) phenyl]-N-[4-(1-naphthyl) phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBNBSF), N,N-bis(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)dibenzo[f,h] quinoxaline-4-amine (abbreviation: FrBiF), N-[4-(1-naphthyl) phenyl]-N-[3-(6-phenyl dibenzo[f,h] quinoxaline-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-fluorene]-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(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluorene-4-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluorene-3-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluorene-2-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-1-amine, and the like.

[0278] Further, as a material having a hole transporting property, the following aromatic amine compounds can also be used: 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), 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B), and the like.

[0279] <Fourth Organic Compound> The fourth organic compound preferably uses a material having an acceptor property with respect to the third organic compound. As a material having an acceptor property, an organic compound having an electron-withdrawing group (halogen group, cyano group, or the like) is preferably used, and an organic compound having at least one of a halogen group and a cyano group in a number of four or more is more preferably used. As specific examples, 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-pyrrolo[2,3-c]pyridin-2-ylidene)propanedinitrile, and the like. In particular, a compound in which an electron-withdrawing group is bonded to a fused aromatic ring including a plurality of hetero atoms such as HAT-CN and the like is thermally stable, and thus is preferable. Further, a [3]radialene derivative having an electron-withdrawing group (particularly, a halogen group such as a fluoro group, a cyano group) has a very high electron-accepting property, and thus is particularly preferable, and specifically, α,α',α"-1,2,3-cyclopropanetriylidene tris[4-cyano-2,3,5,6-tetrafluorobenzonitrile], α,α',α"-1,2,3- cyclopropanetristylyl tris [2,6-dichloro-3,5-difluoro-4- (trifluoromethyl) phenylacetonitrile], α, α', α" -1, 2, 3-cyclopropanetristylyl tris [2, 3, 4, 5, 6-pentafluorophenylacetonitrile], and the like. As the substance having an acceptor property, in addition to the above-mentioned organic compounds, transition metal oxides such as molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, manganese oxide, and the like can be used.

[0280] In the second layer, a signal observed by electron spin resonance observation is preferably observed. For example, the spin density due to a signal observed around g value 2.00 is preferably 1 x 10 17 spins / cm 3 The above, more preferably 1 x 10 18 spins / cm 3 The above, further preferably 1 x 10 19 spins / cm 3 The above. Thereby, the second layer can be used as a charge generation layer. In addition, a light-emitting device having a low driving voltage and high efficiency can be produced.

[0281] [Third Layer] A third layer can also be provided between the first layer and the second layer of the intermediate layer to smoothly perform electron donation and acceptance between the two layers.

[0282] The third layer contains a substance having electron transport property, and can prevent interaction of the first layer and the second layer to smoothly transfer electrons. The LUMO level of the substance having electron transport property 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 contacting the intermediate layer 160 in the light-emitting unit on the first electrode 101 side. Specifically, the LUMO level of the substance having electron transport property used in the third layer 163 is -5.0 eV or more, preferably -5.0 eV or more and -3.0 eV or less, more preferably -4.30 eV or more and -3.00 eV or less, and further preferably -4.30 eV or more and -3.30 eV or less. At this time, it is easy to inject the electrons generated in the second layer into the first layer, and thus the rise in the driving voltage of the light-emitting device can be suppressed, and thus is preferable. In addition, as the substance having electron transport property used in 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, it is possible to use diquinoxalino[2,3-a:2',3'-c]phenazine (abbreviation: HATNA), 2,3,8,9,14,15-hexafluoro-diquinoxalino[2,3-a:2',3'-c]phenazine (abbreviation: HATNA-F6), 3,4,9,10-perylenetetracarboxylic diimide (abbreviation: PTCDI), 3,4,9,10-perylenetetracarboxylic-bis-benzimidazole (abbreviation: PTCBI), and the like perylene tetracarboxylic acid derivatives, (C60-Ih)[5,6]fullerene (abbreviation: C60), (C70-D5h)[5,6]fullerene (abbreviation: C70), phthalocyanine (abbreviation: H2Pc). In addition, it is possible to use copper phthalocyanine (abbreviation: CuPc), zinc phthalocyanine (abbreviation: ZnPc), cobalt phthalocyanine (abbreviation: CoPc), iron phthalocyanine (abbreviation: FePc), tin phthalocyanine (abbreviation: SnPc), oxotin phthalocyanine (abbreviation: SnOPc), oxotitanium phthalocyanine (abbreviation: TiOPc), oxovanadium phthalocyanine (abbreviation: VOPc), and the like metal phthalocyanines containing copper, zinc, cobalt, iron, chromium, nickel, and the like, and derivatives thereof. In particular, it is preferable to use a phthalocyanine-based metal complex such as copper phthalocyanine or zinc phthalocyanine, or 2,3,8,9,14,15-hexafluoro-diquinoxalino[2,3-a:2',3'-c]phenazine.

[0284] In addition, the thickness of the third layer 163 is preferably greater than or equal to 1 nm and less than or equal to 10 nm, and more preferably greater than or equal to 2 nm and less than or equal to 5 nm.

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

[0286] Embodiment 2 In this embodiment mode, another structure of a light-emitting element of one embodiment of the present application is described.

[0287] Figure 8A A light-emitting element 130 of one example of a light-emitting element of one embodiment of the present application is described. The light-emitting element 130 is a light-emitting element including an organic compound layer 103 having a light-emitting layer 113 between a first electrode 101 having an anode and a second electrode 102 having a cathode.

[0288] Figure 8B A light-emitting element 130 of another example of a light-emitting element of one embodiment of the present application is described. The light-emitting element 130 is a tandem light-emitting element. In the light-emitting element 130, an organic compound layer 103 includes a first light-emitting unit 501 having a first light-emitting layer 113_1, a second light-emitting unit 502 having 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] Note that in this embodiment, the light-emitting device including one intermediate layer 160 and two light-emitting units is described as an example, but a light-emitting device including an intermediate layer of n (n is an integer of 1 or more) layers and light-emitting units of n + 1 layers can be used.

[0290] For example, Figure 8C The light-emitting device 130 illustrated in FIG. 1C is an example of a tandem light-emitting device in which n is 2 and the organic compound layer 103 includes the first light-emitting unit 501, the first intermediate layer 160_1, the second light-emitting unit 502, the second intermediate layer 160_2, and the third light-emitting unit 503 including the third light-emitting layer 113_3. The color gamut of light emitted from the light-emitting layer in each light-emitting unit can be the same or different. Further, the light-emitting layer can have a single-layer structure or a stacked-layer structure. For example, the first and third light-emitting units can emit light in the blue region and the light-emitting layer in the stacked-layer structure in the second light-emitting unit can emit light in the red region and light in the green region, whereby white light emission can be obtained.

[0291] For example, Figure 8D The light-emitting device 130 illustrated in FIG. 1C is an example of a tandem light-emitting device in which n is 2 and the organic compound layer 103 includes the first light-emitting unit 501, the first intermediate layer 160_1, the second light-emitting unit 502, the second intermediate layer 160_2, and the third light-emitting unit 503 including the third light-emitting layer 113_3. The color gamut of light emitted from the light-emitting layer in each light-emitting unit can be the same or different. Further, the light-emitting layer can have a single-layer structure or a stacked-layer structure. For example, the first and third light-emitting units can emit light in the blue region and the light-emitting layer in the stacked-layer structure in the second light-emitting unit can emit light in the red region and light in the green region, whereby white light emission can be obtained.

[0292] The light-emitting device 130 can be a light-emitting device manufactured by a photolithography technique, for example. In the case of using a light-emitting device manufactured by a photolithography technique, 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 above layer are processed at the same time, so that the end portions of these layers are aligned in the vertical direction.

[0293] Further, the organic compound layer 103 can include a functional layer other than the light-emitting layer. Figure 8AThe following structure is shown: the organic compound layer 103 is provided with 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. Note that the first light-emitting unit 501 and the second light-emitting unit 502 can also include other functional layers in addition to the light-emitting layer. Figure 8B The following structure is shown: the first light-emitting unit 501 is provided with 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 is provided with 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. Note that the structure of the organic compound layer 103 in this embodiment is not limited to this, and any of the above layers can not be provided, or other layers can be provided. As the other layers, a carrier blocking layer (hole blocking layer, electron blocking layer), an exciton blocking layer, or the like can be typically given.

[0294] Next, the structure of the light-emitting device 130 other than the intermediate layer 160 is described.

[0295] <Structure of first electrode> The first electrode 101 is an electrode including an anode. The first electrode 101 can also have a stacked structure, in which case a layer in contact with the organic compound layer 103 is used as the anode. The anode is preferably formed using a metal, an alloy, a conductive compound, a mixture thereof, or the like having a large work function (specifically, 4.0 eV or more). Specifically, for example, indium tin oxide (ITO), indium tin oxide containing silicon or silicon oxide, indium zinc oxide, indium oxide containing tungsten oxide and zinc oxide (IWZO), or the like can be given. Although these conductive metal oxide films are typically deposited by a sputtering method, they can also be formed by application of a sol-gel method or the like. As an example of a formation method, a method in which a target in which 1 wt% to 20 wt% of zinc oxide is added to indium oxide is used to form indium zinc oxide by a sputtering method, or the like can be given. Further, a target in which 0.5 wt% to 5 wt% of tungsten oxide and 0.1 wt% to 1 wt% of zinc oxide are added to indium oxide can be used to form indium oxide containing tungsten oxide and zinc oxide (IWZO) by a sputtering method. In addition to this, as a material for the anode, for example, gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), a nitride of a metal material (e.g., titanium nitride), or the like can be given. Further, graphene can also be used as a material for the anode. Further, by using the second layer 162 in the above-described intermediate layer 160 as a layer (typically, a hole injection layer) in contact with the anode, the work function need not be taken into account when selecting an electrode material.

[0296] <<Structure of hole injection layer>> The hole injection layer 111 is in contact with the anode and has a function of easily injecting holes into the organic compound layer 103 (the first light emitting unit 501). As the hole injection layer 111, phthalocyanine compounds such as phthalocyanine (abbreviation: H2Pc), copper phthalocyanine (abbreviation: CuPc), or the like; aromatic amine compounds such as 4,4'-bis[N-(4-diphenylamino phenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), 4,4'-bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviation: DNTPD), or the like; or a high molecule such as poly(3,4-ethylenedioxythiophene) / poly(styrenesulfonic acid) (abbreviation: PEDOT / PSS), or the like can be used.

[0297] In addition, the hole injection layer 111 can be formed using a substance having an electron-accepting property. As the substance having an electron-accepting property, the substance described above as the electron-accepting substance for the second layer 162 in the intermediate layer 160 can be used.

[0298] In addition, the hole injection layer 111 can be formed using the hole-transporting material for the second layer 162 in the intermediate layer 160 described above.

[0299] Note that in the hole injection layer 111, the organic compound having a hole-transporting property used in the composite is more preferably a substance having a lower HOMO level with a HOMO level of -5.7 eV or more and -5.4 eV or less. When the organic compound having a hole-transporting property used in the composite has a lower HOMO level, holes are easily injected into the hole-transporting layer, and a light emitting element with a long lifetime can be easily obtained. Furthermore, when the organic compound having a hole-transporting property used in the composite is a substance having a lower HOMO level, the generation of holes is appropriately suppressed, and thus a light emitting element with a longer lifetime can be achieved.

[0300] By forming the hole injection layer 111, the hole-injection property can be improved, and thus a light emitting element with a low driving voltage can be obtained.

[0301] Furthermore, the organic compound having an electron-accepting property in the substance having an electron-accepting property can be easily deposited by evaporation, and is thus a material that is easy to use.

[0302] In addition, since the second layer 162 in the intermediate layer 160 is used as the hole injection layer, the second light emitting unit 502 is not provided with a hole injection layer, but the second light emitting unit 502 can be provided with a hole injection layer.

[0303] <<Structure of hole transport layer>> The hole-transport layer (first hole-transport layer 112_1, second hole-transport layer 112_2) is formed of an organic compound having a hole-transport property. The organic compound having a hole-transport property preferably has a hole mobility of 1 x 10 -6 cm 2 or more.

[0304] As the above-mentioned material having a hole-transport property, there can be mentioned 4,4'-bis[N-(l-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-fluorene]-2-yl)-N,N'-diphenyl-4,4'-diaminobiphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 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-(l-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(l-naphthyl)-4"-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF), and the like having an aromatic amine skeletal structure.1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-bis(N-carbazolyl)diphenyl (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''-terphenyl]-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'-(triphenylene-2-yl)-3,3'-9H,9'H-bicarbazole, 9-phenyl-9'-(triphenylene-2-yl)-3,3'-9H,9'H-bicarbazole (abbreviation: PCCzTp), 9,9'-bis(triphenylene-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(4-biphenyl)-9'-(triphenylene-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(triphenylene-2-yl)-9'-[1,1':3',1''-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, and the like having a carbazole skeleton;4,4',4"-(benzene-1,3,5-triyl)tris(dibenzothiophene) (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and the like having a thiophene skeleton; and 4,4',4"-(benzene-1,3,5-triyl)tris(dibenzofuran) (abbreviation: DBF3P-II), 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II), and the like having a furan skeleton. Among them, the compound having an aromatic amine skeleton and the compound having a carbazole skeleton have good reliability and high hole-transport properties and are effective in reducing the driving voltage, and thus are preferable. In addition, a substance that can be exemplified as a material having a hole-transport property used for the composite material of the hole-injection layer 111 is appropriately used as a material constituting the hole-transport layer.

[0305] <<Structure of Light-emitting Layer>> The light-emitting layer (the light-emitting layer 113, the first light-emitting layer 113_1, and the second light-emitting layer 113_2) preferably contains a light-emitting substance and a host material. Note that the light-emitting layer can further contain another material. In addition, the light-emitting layer can be formed to have two layers with different compositions stacked.

[0306] The light-emitting substance can be a fluorescent light-emitting substance, a phosphorescent light-emitting substance, a substance exhibiting thermally activated delayed fluorescence (TADF), or another light-emitting substance.

[0307] In the light-emitting layer, as a material that can be used as a fluorescent light-emitting substance, the following substances can be given, for example. Note that other fluorescent light-emitting substances can be used in addition to these.

[0308] 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 (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-butylanthracen-9,10-diylbis-4,1-phenylene)bis(N,N',N'-triphenyl-1,4- phenylenediamine) (abbreviation: DPABPA), N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), N,N,N',N',N",N",N",N"'-octaphenylchrysene-2,7-diamine (abbreviation: OCAP), N,N,N',N',N"-2,6-di-tert-butyldibenzo[C,H]xanthene-5,6-diamine (abbreviation: DBH), 4-(9-phenyl-9H-fluoren-9-yl)-4'-(9H-carbazol-9-yl)triphenylamine (abbreviation: PCzPA), N-phenyl-9-phenyl-9H-carbazol-3-amine (abbreviation: PCA), N-phenyl-9,10-diphenylanthracen-2-amine (abbreviation: DPA), and the like. -2,7,10,15-tetramine (abbreviation: DBC1), Coumarin 30, N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazole-3-amine (abbreviation: 2PCAPA), N-[9,10-bis(2-phenyl-1-biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazole-3-amine (abbreviation: 2PCABPhA), N-(9,10-diphenyl-2-anthryl)-N,N',N'-triphenyl-1,4-phenylene-diamine (abbreviation: 2DPAPA), 9,10-bis(2-biphenyl-2-yl)-2-(N,N',N'-triphenyl-1,4-phenylene-diamine-N-yl)anthracene (abbreviation: 2DPABPhA), 9,10-bis(2-biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracene-2-amine (abbreviation: 2YGABPhA), N,N,9-triphenylanthracen-9-amine (abbreviation: DPhAPhA), Coumarin 545T, N,N'-diphenylquinacridone (abbreviation: DPQd), Rubrene, 5,12-bis(1,1'-biphenyl-4-yl)-6,11-diphenylbenzo- tetraphene (abbreviation: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyran-4- ylidene)malonitrile (abbreviation: DCM1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizol-9-yl)ethenyl]-4H-pyran-4- ylidene}malonitrile (abbreviation: DCM2), N,N,N',N'-tetrakis(4-methylphenyl) naphthacene-5,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N',N'-tetrakis(4-methylphenyl) acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviation: p-mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizol-9-yl)ethenyl]-4H-pyran-4- ylidene}malonitrile (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizol-9-yl)ethenyl]-4H-pyran-4- ylidene}malonitrile (abbreviation: DCJTB), 2-(2,6-bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4- ylidene)malonitrile (abbreviation: BisDCM), 2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizol-9-yl)ethenyl]-4H-pyran-4- ylidene}malonitrile (abbreviation: BisDCJTM), N,N'-diphenyl-N,N'-(1,6-pyrene-diyl)bis[(6-phenylbenzo[b]naphtho[1,2-d] furan)-8-amine] (abbreviation: 1,6BnfAPrn-03), N,N'-diphenyl-N,N'-bis(9-phenyl-9H-carbazol-2-yl)naphtho[2,3-b;6,7-b']bisbenzo furan-3,10-diamine (abbreviation: 3,10PCA2Nbf(IV)-02), 3,10-bis[N-(dibenzo furan-3-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzo furan (abbreviation: 3,10FrA2Nbf(IV)-02), and the like. In particular, fused aromatic diamine compounds typified by pyrene diamine compounds such as 1,6FLPAPrn, 1,6mMemFLPAPrn, 1,6BnfAPrn-03, and the like have good hole-trapping properties and high luminous efficiency or good reliability, and thus are preferable.

[0309] When a phosphorescent light-emitting material is used as a light-emitting material in the light-emitting layer, as a material that can be used, for example, the following materials can be given.

[0310] Ir(III) (abbreviation: [Ir(mpptz-dmp)3]), tris(5-methyl-3,4-diphenyl-4H-l,2,4-triazole) iridium(III) (abbreviation: [Ir(Mptz)3]), tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-l,2,4-triazole] iridium(III) (abbreviation: [Ir(iPrptz-3b)3]), and the like, which are organometallic iridium complexes having a 4H-triazole skeleton; tris[3-methyl-l-(2-methylphenyl)-5-phenyl-lH-l,2,4-triazole] iridium(III) (abbreviation: [Ir(Mptzl-mp)3]), tris(l-methyl-5-phenyl-3-propyl-lH-l,2,4-triazole) iridium(III) (abbreviation: [Ir(Prptzl-Me)3]), and the like, which are organometallic iridium complexes having a lH-triazole skeleton; fac-tris[l-(2,6-diisopropylphenyl)-2-phenyl-lH-imidazole] iridium(III) (abbreviation: [Ir(iPrpim)3]), tris[3-(2,6-dimethylphenyl)-7-methylimidazo[l,2-f]phenanthridinato] iridium(III) (abbreviation: [Ir(dmpimpt-Me)3]), and the like, which are organometallic iridium complexes having an imidazole skeleton; and bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ] iridium(III) tetrakis(l-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’ ] iridium(III) acetylacetonate (abbreviation: FIracac), and the like. The above substances are compounds that emit blue phosphorescence and have a light-emission peak in a wavelength region of 450 nm to 520 nm.

[0311] In addition, there are iridium(III) tris(4-methyl-6-phenylpyrimidinate) (abbreviation: [Ir(mppm)3]), iridium(III) tris(4-tert-butyl-6-phenylpyrimidinate) (abbreviation: [Ir(tBuppm)3]), iridium(III) (acetylacetonato) bis(6-methyl-4-phenylpyrimidinate) (abbreviation: [Ir(mppm)2(acac)]), iridium(III) (acetylacetonato) bis(6-tert-butyl-4-phenylpyrimidinate) (abbreviation: [Ir(tBuppm)2(acac)]), iridium(III) (acetylacetonato) bis[6-(2-norbornyl)-4-phenylpyrimidinate] (abbreviation: [Ir(nbppm)2(acac)]), iridium(III) (acetylacetonato) bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidinate] (abbreviation: [Ir(mpmppm)2(acac)]), iridium(III) (acetylacetonato) bis(4,6-diphenylpyrimidinate) (abbreviation: [Ir(dppm)2(acac)]), and the like, which are organic metal iridium complexes having a pyrimidine skeleton; iridium(III) (acetylacetonato) bis(3,5-dimethyl-2-phenylpyrazinato) (abbreviation: [Ir(mppr-Me)2(acac)]), iridium(III) (acetylacetonato) bis(5-isopropyl-3-methyl-2-phenylpyrazinato) (abbreviation: [Ir(mppr-iPr)2(acac)]), and the like, which are organic metal iridium complexes having a pyrazine skeleton; iridium(III) 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]quinolinate) iridium(III) acetylacetonate (abbreviation: [Ir(bzq)2(acac)]), tris(benzo[h]quinoline) iridium(III) (abbreviation: [Ir(bzq)3]), tris(2-phenylquinoline-N,C 2’iridium(III) (abbreviation: [Ir(pq)3]), bis(2-phenylquinoline-N, C 2’ ) iridium(III) acetylacetonate (abbreviation: [Ir(pq)2(acac)]), [2-d3-methyl-8-(2-pyridyl-κN)benzofuran[2,3-b]pyridine-κC]bis[2-(5-d3-methyl-2-pyridyl-κN2)phenyl-κC]iridium(III) (abbreviation: Ir(5mppy-d3)2(mbfpypy-d3)), {2-(methyl-d3)-8-[4-(1-methylethyl-1-d)-2-pyridyl-κN]benzofuran[2,3-b]pyridine-7-yl-κC}bis{5-(methyl-d3)-2-[5-(methyl-d3)-2-pyridyl-κN]phenyl-κC}iridium(III) (abbreviation: Ir(5mtpy-d6)2(mbfpypy-iPr-d4)), [2-d3-methyl-(2-pyridyl-κN)benzofuran[2,3-b]pyridine-κC]bis[2-(2-pyridyl-κN)phenyl-κC]iridium(III) (abbreviation: Ir(ppy)2(mbfpypy-d3)), [2-(4-methyl-5-phenyl-2-pyridyl-κN)phenyl-κC]bis[2-(2-pyridyl-κN)phenyl-κC]iridium(III) (abbreviation: Ir(ppy)2(mdppy)), and the like organic metal iridium complexes having a pyridine skeleton; and tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviation: [Tb(acac)3(Phen)]) and the like rare earth metal complexes. The above substances are mainly compounds that exhibit green phosphorescence, and have a light emission peak in a wavelength region of 500 nm to 600 nm. In addition, since the organic metal iridium complexes having a pyrimidine skeleton have particularly excellent reliability or light emission efficiency, they are particularly preferable.

[0312] In addition, there can be mentioned: (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III) (abbreviation: [Ir(5mdppm)2(dibm)]), bis[4,6-bis(3-methylphenyl)pyrimidinato](dineopentylmethanato)iridium(III) (abbreviation: [Ir(5mdppm)2(dpm)]), bis[4,6-di(naphthalen-1-yl)pyrimidinato](dineopentylmethanato)iridium(III) (abbreviation: [Ir(d1npm)2(dpm)]), and the like, which are organometallic iridium complexes having a pyrimidine skeleton; (acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: [Ir(tppr)2(acac)]), bis(2,3,5-triphenylpyrazinato)(dineopentylmethanato)iridium(III) (abbreviation: [Ir(tppr)2(dpm)]), (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: [Ir(Fdpq)2(acac)]), and the like, which are organometallic iridium complexes having a pyrazine skeleton; tris(1-phenylisoquinoline-N,C 2’ )iridium(III) (abbreviation: [Ir(piq)3]), bis(1-phenylisoquinoline-N,C 2’ )iridium(III) acetylacetonate (abbreviation: [Ir(piq)2(acac)]), and the like, which are organometallic iridium complexes having a pyridine skeleton; 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphine platinum(II) (abbreviation: PtOEP), and the like, which are platinum complexes; and tris(1,3-diphenyl-1,3-propanedionato)(phenanthroline)europium(III) (abbreviation: [Eu(DBM)3(Phen)]), tris[1-(2-thienoyl)-3,3,3-trifluoropropanedionato](phenanthroline)europium(III) (abbreviation: [Eu(TTA)3(Phen)]), and the like, which are rare earth metal complexes. The above substances are compounds that exhibit red phosphorescence, and have a light-emitting peak in a wavelength region of 600 nm to 700 nm. In addition, the organometallic iridium complexes having a pyrazine skeleton can obtain red light emission with good color rendering.

[0313] In addition, a known phosphorescent compound can be used in addition to the above phosphorescent compound.

[0314] As the TADF material, fullerene and derivatives thereof, acridine and derivatives thereof, and eosin derivatives, etc. can be used. Further, metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd), etc. can also be cited. As the metal-containing porphyrin, for example, protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hemoporphyrin-tin fluoride complex (SnF2(Hemato IX)), copro porphyrin 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), etc. represented by the following structural formulas can be cited.

[0315] [Chemical Formula 20]

[0316] Further, 2-(diphenyl-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-phenoxazine-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: PXZ-TRZ), 3-[4-(5-phenyl-5,10-dihydrophenazine-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-dihydroacridin)phenyl]sulfide (abbreviation: DMAC-DPS), 10-phenyl-10H,10'H-spiro[acridine-9,9'-xanthene]-10'-one (abbreviation: ACRSA), and the like including a heterocyclic compound including one or both of a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring. The heterocyclic compound is preferable because it has high electron-transport properties and high hole-transport properties due to the inclusion of the π-electron rich heteroaromatic ring and the π-electron deficient heteroaromatic ring. Among them, in a skeleton including a π-electron deficient heteroaromatic ring, a pyridine skeleton, a diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), and a triazine skeleton are stable and have high reliability, and thus are preferable. In particular, a benzofuranopyrimidine skeleton, a benzothienopyrimidine skeleton, a benzofuranopyrazine skeleton, and a benzothienopyrazine skeleton have high acceptor properties and have high reliability, and thus are preferable. Further, in a skeleton having a π-electron rich heteroaromatic ring, an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, a thiophene skeleton, and a pyrrole skeleton are stable and have high reliability, and thus it is preferable to have at least one of the above-described skeletons. Further, a dibenzofuran skeleton is preferable as the furan skeleton, and a dibenzothiophene skeleton is preferable as the thiophene skeleton. As the pyrrole skeleton, an indole skeleton, a carbazole skeleton, an indolocarbazole skeleton, a bicarbazole skeleton, and a 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole skeleton are particularly preferable. In addition, in a substance in which a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring are directly bonded, both the electron-donating property of the π-electron rich heteroaromatic ring and the electron-accepting property of the π-electron deficient heteroaromatic ring are high, and the energy difference between the S1 energy level and the T1 energy level is small, and thus heat-activated delayed fluorescence can be obtained with high efficiency, and thus is particularly preferable. Note that an aromatic ring having an electron-withdrawing group such as a cyano group instead of the π-electron deficient heteroaromatic ring can also be used.Further, as the π-electron rich skeleton, an aromatic amine skeleton, a phenoxazine skeleton, and the like can be used. Further, as the π-electlectron deficient skeleton, an xanthene skeleton, a thioxanthene dioxide skeleton, an oxadiazole skeleton, a triazole skeleton, an imidazole skeleton, an anthraquinone skeleton, a boron-containing skeleton such as a phenylborane, a boranthrene, an aromatic ring or a heteroaromatic ring having a nitrile group or a cyano group such as a benzonitrile or a cyanobenzene, a carbonyl skeleton such as a benzophenone, a phosphine oxide skeleton, a sulfone skeleton, and the like can be used. Thus, at least one of the π-electron deficient heteroaromatic ring and the π-electron rich heteroaromatic ring can be replaced with the π-electron deficient skeleton and the π-electron rich skeleton.

[0317] [Chemical Formula 21]

[0318] Further, as the TADF material, a TADF material in a thermal equilibrium state between the singlet excited state and the triplet excited state can be used. Such a TADF material has a short luminescence lifetime (excitation lifetime), and thus can suppress a decrease in efficiency in a high luminance region of the light-emitting device. Specifically, a material having the following molecular structure can be given.

[0319] [Chemical Formula 22]

[0320] Note that the TADF material refers to a material in which the difference between the S1 level and the T1 level is small and which has a function of converting triplet excitation energy into singlet excitation energy by reverse intersystem crossing. Thus, the triplet excitation energy can be up-converted into the singlet excitation energy (reverse intersystem crossing) by a small amount of thermal energy and the singlet excited state can be efficiently generated. Further, the triplet excitation energy can be converted into luminescence.

[0321] An exciplex in which two substances form an excited state has a function of the TADF material in which the difference between the S1 level and the T1 level is extremely small and which can convert the triplet excitation energy into the singlet excitation energy.

[0322] Note that as an index of the T1 level, a phosphorescence spectrum observed at a low temperature (e.g., 77 K to 10 K) can be used. In the case of the TADF material, it is preferable that, when the wavelength energy of an extrapolation line obtained by drawing a tangent line at the tail on the short wavelength side of a fluorescence spectrum is the S1 level and the wavelength energy of an extrapolation line obtained by drawing a tangent line at the tail on the short wavelength side of a phosphorescence spectrum is the T1 level, the difference between the S1 and the T1 is 0.3 eV or less, and more preferably 0.2 eV or less.

[0323] Further, when a TADF material is used as the light-emitting substance, the S1 energy level of the host material is preferably higher than the S1 energy level of the TADF material. Further, the T1 energy level of the host material is preferably higher than the T1 energy level of the TADF material.

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

[0325] As the material having hole-transporting property, the above-described material having hole-transporting property can be similarly used.

[0326] As the material having electron-transporting property, the above-described material having electron-transporting property can be similarly used.

[0327] As the TADF material that can be used as the host material, the above-described material as the TADF material can be similarly used. When a TADF material is used as the host material, the triplet excitation energy generated from the TADF material is converted into singlet excitation energy through reverse intersystem crossing and further transferred to the light-emitting substance, whereby the light-emitting efficiency of the light-emitting device can be improved. At this time, the TADF material is used as an energy donor and the light-emitting substance is used as an energy acceptor.

[0328] This is particularly effective when the above-described light-emitting substance is a fluorescent light-emitting substance. Further, at this time, in order to obtain high light-emitting efficiency, the S1 energy level of the TADF material is preferably higher than the S1 energy level of the fluorescent light-emitting substance. Further, the T1 energy level of the TADF material is preferably higher than the S1 energy level of the fluorescent light-emitting substance. Therefore, the T1 energy level of the TADF material is preferably higher than the T1 energy level of the fluorescent light-emitting substance.

[0329] Further, it is preferable to use a TADF material that exhibits luminescence overlapping with the wavelength of the absorption band on the lowest energy side of the fluorescent light-emitting substance. Thereby, the excitation energy is smoothly transferred from the TADF material to the fluorescent light-emitting substance, and luminescence can be obtained efficiently, and thus is preferable.

[0330] In order to efficiently generate singlet excitation energy from triplet excitation energy via reverse intersystem crossing, carrier recombination is preferably generated in the TADF material. Furthermore, it is preferable that triplet excitation energy generated in the TADF material is not transferred to triplet excitation energy of the fluorescent light emitting substance. For this purpose, the fluorescent light emitting substance preferably has a protective group around an emitter (skeleton that is the cause of light emission) possessed by the fluorescent light emitting substance. As the protective group, a substituent having no π bond is preferable, a saturated hydrocarbon is preferable, and specifically, an alkyl group having 3 or more and 10 or less carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 or more and 10 or less carbon atoms, a trialkylsilyl group having 3 or more and 10 or less carbon atoms can be mentioned, and more preferably, a plurality of protective groups are provided. The substituent having no π bond has little function of transporting a carrier, and therefore has little influence on carrier transport or carrier recombination, and the TADF material and the emitter of the fluorescent light emitting substance can be made to be apart from each other. Here, the emitter refers to an atomic group (skeleton) that is the cause of light emission in the fluorescent light emitting substance. The emitter is preferably a skeleton having a π bond, preferably includes an aromatic ring, and preferably includes a fused aromatic ring or a fused heteroaromatic ring. As the above emitter, for example, 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 skeleton, a triphenylene skeleton, a tetracene skeleton, a pyrene skeleton, a perylene skeleton, a coumarin skeleton, a quinacridone skeleton, a naphthobischromenofuran skeleton, and the like can be mentioned. In particular, the fluorescent light emitting substance having a naphthalene skeleton, an anthracene skeleton, a fluorene skeleton, a skeleton, a triphenylene skeleton, a tetracene skeleton, a pyrene skeleton, a perylene skeleton, a coumarin skeleton, a quinacridone skeleton, a naphthobischromenofuran skeleton, and the like can be mentioned. In particular, the fluorescent light emitting substance having a naphthalene skeleton, an anthracene skeleton, a fluorene skeleton,

[0331] In the case where a fluorescent light emitting substance is used as the light emitting substance, as the host material, a material having an anthracene skeleton is preferably used. By using a substance having an anthracene skeleton as the host material of the fluorescent light emitting substance, a light emitting layer having both high emission efficiency and durability can be realized. Among the substances having an anthracene skeleton used as the host material, a substance having a diphenyl anthracene skeleton, and particularly a substance having a 9, 10-diphenyl anthracene skeleton is chemically stable, and thus is preferable. In addition, when the host material has a carbazole skeleton, the hole injection / transport property is improved, and thus is preferable, but when a benzocarbazole skeleton having a benzene ring further condensed to the carbazole skeleton is present, the HOMO is higher than that of the host material having a carbazole skeleton by about 0.1 eV, and thus holes are easily injected, and thus is more preferable. Particularly, in the case where the host material has a dibenzocarbazole skeleton, the HOMO thereof is higher than that of the host material having a carbazole skeleton by about 0.1 eV, and thus not only holes are easily injected, but also the hole transport property and heat resistance are improved, and thus is preferable. Therefore, as the host material, a substance having both a 9, 10-diphenyl anthracene skeleton and a carbazole skeleton (or a benzocarbazole skeleton or a dibenzocarbazole skeleton) is further preferable. Note that, from the viewpoint of the hole injection / transport property described above, a benzofluorene skeleton or a dibenzofluorene skeleton can also be used instead of a carbazole skeleton. As examples of such a substance, 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-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA), 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA), 6-[3-(9,10-diphenyl-2-anthryl)phenyl]benzo[b]naphtho[1,2-d]furan (abbreviation: 2mBnfPPA), 9-phenyl-10-[4'-(9-phenyl-9H-fluoren-9-yl)biphenyl-4-yl]anthracene (abbreviation: FLPPA), 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: aN-βNPAnth), 9-(1-naphthyl)-10-(2-naphthyl)anthracene (abbreviation: a, β-ADN), 2-(10-phenylanthracen-9-yl)dibenzofuran, 2-(10-phenyl-9-anthryl)benzo[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-anthryl]phenyl}-2-ethyl-1H-benzimidazole (abbreviation: EtBImPBPhA), and the like can be given. Particularly, CzPA, cgDBCzPA, 2mBnfPPA, and PCzPA exhibit very good characteristics, and thus are preferable.

[0332] Further, the host material can also be a material in which a plurality of substances are mixed. When a mixed host material is used, it is preferable to mix a material having electron-transport property and a material having hole-transport property. By mixing a material having electron-transport property and a material having hole-transport property, it is possible to easily adjust the transport property of the light-emitting layer 113, and it is also possible to easily control the recombination region. The weight ratio of the content of the material having hole-transport property to the material having electron-transport property is 1:19 to 19:1.

[0333] Note that as part of the above-described mixed material, a phosphorescent light-emitting substance can be used. The phosphorescent light-emitting substance can be used as an energy donor that supplies excitation energy to a fluorescent light-emitting substance when the fluorescent light-emitting substance is used as a light-emitting substance.

[0334] Further, the mixed material can also be used to form an exciplex. By selecting a combination of materials that form an exciplex that emits light whose wavelength overlaps with the absorption band on the lowest energy side of a light-emitting substance, energy transfer can be made smooth, and thus light emission can be obtained efficiently, which is preferable. Further, by driving with this structure, the driving voltage is also reduced, which is preferable.

[0335] Note that at least one of the materials that form the exciplex can be a phosphorescent light-emitting substance. Thus, it is possible to efficiently convert triplet excitation energy into singlet excitation energy through reverse intersystem crossing.

[0336] As for the combination of materials that efficiently form an exciplex, the HOMO level of the material having hole-transport property is preferably higher than or equal to the HOMO level of the material having electron-transport property. Further, the LUMO level of the material having hole-transport property is preferably higher than or equal to the LUMO level of the material having electron-transport property. Note that the LUMO level and the HOMO level of a material can be found from the electrochemical characteristics (reduction potential and oxidation potential) of the material measured by cyclic voltammetry (CV).

[0337] Note that formation of the exciplex can be confirmed, for example, by comparing an emission spectrum of a material having a hole-transport property, an emission spectrum of a material having an electron-transport property, and an emission spectrum of a mixed film in which these materials are mixed, and observing a phenomenon in which the emission spectrum of the mixed film shifts to the longer wavelength side (or has a new peak on the longer wavelength side) than the emission spectra of the materials. Alternatively, formation of the exciplex can be confirmed by comparing a transient photoluminescence (PL) of a material having a hole-transport property, a transient PL of a material having an electron-transport property, and a transient PL of a mixed film in which these materials are mixed, and observing a difference in transient response, such as a larger proportion of a long-lifetime component or a delay component in the transient PL lifetime of the mixed film than in the transient PL lifetime of the materials. Note that the above transient PL can be referred to as transient electroluminescence (EL). In other words, formation of the exciplex can be confirmed by comparing a transient EL of a material having a hole-transport property, a transient EL of a material having an electron-transport property, and a transient EL of a mixed film in which these materials are mixed, and observing a difference in transient response.

[0338] <<Structure of Electron Transport Layer>> The electron-transport layer (the electron-transport layer 114, the first electron-transport layer 114_1, the second electron-transport layer 114_2) is a layer containing a substance having an electron-transport property. As the material having an electron-transport property, a substance having an electron mobility of 1 x 10 -7 cm 2 / Vs or higher, preferably 1 x 10 -6 cm 2 / Vs or higher is preferable. Note that a substance other than the above can be used as long as the substance has a higher electron-transport property than a hole-transport property. As the above organic compound, an organic compound including a heteroaromatic ring having a π-electron deficient type is preferably used. As the organic compound including a heteroaromatic ring having a π-electlon deficient type, one or more of an organic compound including a heteroaromatic ring having an oxazole skeleton, an organic compound including a heteroaromatic ring having a pyridine skeleton, an organic compound including a heteroaromatic ring having a diazine skeleton, and an organic compound including a heteroaromatic ring having a triazine skeleton are preferably used.

[0339] As the organic compound having electron-transporting properties that can be used in the electron-transporting layer, the same organic compound as that which can be used in the organic compound having electron-transporting properties in the first layer of the intermediate layer 160 described above can be used. In particular, an organic compound including a heteroaromatic ring having a diazine skeleton, an organic compound including a heteroaromatic ring having a pyridine skeleton, or an organic compound including a heteroaromatic ring having a triazine skeleton has good reliability, and is thus preferred. In particular, an organic compound including a heteroaromatic ring having a diazine (pyrimidine or pyrazine) skeleton or an organic compound including a heteroaromatic ring having a triazine skeleton has high electron-transporting properties, and is thus helpful in reducing the driving voltage.

[0340] Further, the electron-transporting layer preferably has an electron mobility of 1 x 10 -7 cm 2 / Vs or more and 5 x 10 -5 cm 2 / Vs or less. By reducing the electron-transporting properties in the electron-transporting layer, the amount of electron injection into the light-emitting layer can be controlled, and thus the light-emitting layer can be prevented from becoming in an electron-rich state. In particular, when the hole-transporting material in the composite material used to form the hole-injecting layer has a low HOMO level of -5.7 eV or more and -5.4 eV or less, a long lifetime can be obtained by employing the above structure, and is thus particularly preferred. Note that, in this case, the HOMO level of the material having electron-transporting properties is preferably -6.0 eV or more.

[0341] For example, as the electron-transporting material that can be used in the electron-transporting layer, a heteroaromatic compound can be used. Note that the heteroaromatic compound refers to a ring compound including at least two different elements in a ring. Note that the ring structure includes a three-membered ring, a four-membered ring, a five-membered ring, a six-membered ring, and the like, and a five-membered ring or a six-membered ring is particularly preferred. Further, as the elements included in the heteroaromatic compound, one or more of nitrogen, oxygen, sulfur, and the like, in addition to carbon, are preferred. A heteroaromatic compound including nitrogen (nitrogen-containing heteroaromatic compound) is particularly preferred, and a material (electron-transporting material) having high electron-transporting properties, such as a nitrogen-containing heteroaromatic compound or a π-electron deficient heteroaromatic compound including a nitrogen-containing heteroaromatic compound, is preferably used. The compound of Embodiment 1 can be used as the electron-transporting material because it has electron-transporting properties.

[0342] Note that the electron transport material can use a material different from the material used for the light-emitting layer. Not all excitons generated by the recombination of carriers in the light-emitting layer can contribute to luminescence, and sometimes diffuse to the layer in contact with or near the light-emitting layer. To avoid this phenomenon, the energy level (lowest singlet excitation energy level or lowest triplet excitation energy level) of the material used for the layer in contact with or near the light-emitting layer is preferably higher than that of the material used for the light-emitting layer. Therefore, when the electron transport material uses a material different from the material used for the light-emitting layer, a highly efficient element can be obtained.

[0343] Heteroaromatic compounds are organic compounds that include at least one heteroaromatic ring.

[0344] Note that the heteroaromatic ring includes any of a pyridine ring, a diazine ring, a triazine ring, an azole ring, an oxazole ring, and a thiazole ring. Furthermore, heteroaromatic rings including a pyrimidine ring, a pyrazine ring, or a pyridazine ring are included in the heteroaromatic ring including a diazine ring. Furthermore, heteroaromatic rings including an imidazole ring, a triazole ring, and an oxadiazole ring are included in the heteroaromatic ring including an azole ring.

[0345] The heteroaromatic ring includes a fused heteroaromatic ring having a fused ring structure. Note that examples of the fused heteroaromatic ring include 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 furanodiazine ring, and a benzimidazole ring.

[0346] Note that, for example, among heteroaromatic compounds containing one or more of nitrogen, oxygen, sulfur, etc. in addition to carbon, as heteroaromatic compounds having a five-membered ring structure, there can be mentioned heteroaromatic compounds including an imidazole ring, heteroaromatic compounds including a triazole ring, heteroaromatic compounds including an oxazole ring, heteroaromatic compounds including an oxadiazole ring, heteroaromatic compounds including a thiazole ring, heteroaromatic compounds including a benzimidazole ring, and the like.

[0347] For example, 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 containing heteroaromatic rings such as pyridine rings, diazine rings (including pyrimidine rings, pyrazine rings, pyridazine rings, etc.), triazine rings, and azole rings. Note that heteroaromatic compounds having a bipyridine structure and heteroaromatic compounds having a terpyridine structure are also included in heteroaromatic compounds connected to pyridine rings.

[0348] Furthermore, examples of heteroaromatic compounds having a fused ring structure part of which includes the above-mentioned six-membered ring structure include heteroaromatic compounds having fused heteroaromatic rings such as a quinoline ring, a benzoquinoline ring, a quinoxaline ring, a dibenzoquinoxaline ring, a phenanthroline ring, a furanodiazine ring (including a structure in which a furan ring and an aromatic ring are fused to a furanodiazine ring), and a benzimidazole ring.

[0349] As specific examples of the heteroaromatic compound having the above-mentioned five-membered ring structure (oxazole ring (including imidazole ring, triazole ring, oxadiazole ring), oxazole ring, thiazole ring, benzimidazole ring, etc.), PBD, 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1,2,4-triazole (abbreviation: p-EtTAZ), 2,2',2"-(1,3,5-benzinetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzo-thiophene-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOS), and the like can be given.

[0350] As specific examples of the heteroaromatic compound having the above six-membered ring structure (heteroaromatic ring of a pyridine ring, a diazine ring, a triazine ring, etc.), 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy), 1,3,5-tris[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), and the like including a heteroaromatic ring having a pyridine ring, PCCzPTzn, 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: 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-fluorene]-2-yl)-1,3,5-triazine (abbreviation: BP-SFTzn), 2,6-bis(4-naphthalen-1-ylphenyl)-4-[4-(3-pyridyl)phenyl]pyrimidine (abbreviation: 2,4NP-6PyPPm), 3-[9-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]-9-phenyl-9H-carbazole (abbreviation: PCDBfTzn), 2-(biphenyl-3-yl)-4-phenyl-6-{8-[(1,1':4',1''-terphenyl)-4-yl]-1-dibenzofuranyl}-1,3,5-triazine (abbreviation: mBP-TPDBfTzn), 2-{3-[3-(dibenzothiophene-4-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mDBtBPTzn), mFBPTzn, and the like including a heteroaromatic ring having a triazine ring, 4,6-bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(dibenzothiophene-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 (abbreviation: 6mBP-4Cz2PPm), 4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenyl-6-(biphenyl-4-yl)pyrimidine (abbreviation: 6BP-4Cz2PPm), 4-[3-(dibenzothiophene-4-yl)phenyl]-8-(naphthalen-2-yl)-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8βN-4mDBtPBfpm), 8BP-4mDBtPBfpm, 9mDBtBPNfpr, 9pmDBtBPNfpr, 3,8-bis[3-(dibenzo-thiophen-4-yl)phenyl]benzo-furo[2,3-b]pyrazine (abbreviation: 3,8mDBtP2Bfpr), 4,8-bis[3-(dibenzo-thiophen-4-yl)phenyl]-[l]benzo-furo[3,2-d]pyrimidine (abbreviation: 4,8mDBtP2Bfpm), 8-[3'-(dibenzo-thiophen-4-yl)biphenyl-3-yl]naphtho[l',2':4,5]furo[3,2-d]pyrimidine (abbreviation: 8mDBtBPNfpm), 8-[(2,2'-binaphthalenyl)-6-yl]-4-[3-(dibenzo-thiophen-4-yl)phenyl]-[l]benzo-furo[3,2-d]pyrimidine (abbreviation: 8(βN2)-4mDBtPBfpm), and the like including a heteroaromatic compound having a diazine (pyrimidine) ring and the like. Note that the aromatic compound including the above heteroaromatic ring contains a heteroaromatic compound having a condensed heteroaromatic ring.

[0351] In addition to the above, 2,2'-(pyridine-2,6-diyl)bis(4-phenylbenzo[h]quinoline) (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), 6mBP-4Cz2PPm, and the like including a heteroaromatic compound having a diazine (pyrimidine) ring; 2,4,6-tris[3'-(pyridine-3-yl)biphenyl-3-yl]-l,3,5-triazine (abbreviation: TmPPPyTz), 2,4,6-tris(2-pyridyl)-l,3,5-triazine (abbreviation: 2Py3Tzn), 2-[3-(2,6-dimethyl-3-pyridyl)-5-(9-phenanthryl)phenyl]-4,6-diphenyl-l,3,5-triazine (abbreviation: mPn-mDMePyPTzn), and the like including a heteroaromatic compound having a triazine ring, and the like can be given.

[0352] As specific examples of the heteroaromatic compound having a fused ring structure including the above six-membered ring structure as a part thereof (heteroaromatic compound having a fused ring structure), bathophenanthroline (abbreviation: BPhen), bathocuproin (abbreviation: BCP), NBPhen, mPPhen2P, 2,2'-biphenyl-4,4'-diylbis(9-phenyl-1,10-phenanthroline) (abbreviation: PPhen2BP), 2,6(P-Bqn)2Py, 2-[3-(dibenzo-thiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzo-thiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzo-thiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDBTPDBq-II), and 6-[3-(dibenzo-thiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), a heteroaromatic compound having a quinoxaline ring such as 2mpPCBPDBq, and the like can be given.

[0353] As the metal complex, tris(8-hydroxyquinoline)aluminum (III) (abbreviation: Alq3), Almq3, 8-hydroxyquinoline-lithium (abbreviation: Liq), BeBq2, bis(2-methyl-8-hydroxyquinoline)(4-phenylphenol)aluminum (III) (abbreviation: BAlq), bis(8-hydroxyquinoline)zinc (II) (abbreviation: Znq), a metal complex having a quinoline ring or a benzoquinoline ring such as the like can be given.

[0354] Further, as the electron-transporting material, a high molecular compound such as poly(2,5-pyridinediyl) (abbreviation: PPy), poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)] (abbreviation: PF-Py), poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2'-bipyridine-6,6'-diyl)] (abbreviation: PF-BPy), and the like can be used.

[0355] Note that the electron-transporting layer is not limited to a single layer, and can have a structure in which two or more layers formed of the above-described substances are stacked.

[0356] <Structure of Electron-Injecting Layer> As the electron-injecting layer 115, a layer containing an alkali metal, an alkaline earth metal, a rare earth metal, or a compound or complex thereof, such as lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF2), 8-hydroxyquinoline-lithium (abbreviation: Liq), ytterbium (Yb), or the like can be provided. The electron-injecting layer 115 can use a layer in which an alkali metal, an alkaline earth metal, or a compound thereof is contained in a layer formed of a substance having an electron-transporting property or an electride. As the electride, for example, a substance in which a mixed oxide of calcium and aluminum adds an electron at a high concentration can be given.

[0357] Note that as the electron-injecting layer 115, a layer in which a substance having an electron-transporting property (preferably, an organic compound having a bipyridine skeleton) is contained in a concentration of a fluoride of the above-described alkali metal or alkaline earth metal at 50 wt % or more (50 wt % or more) in a microcrystalline state can be used. Since this layer is a layer with a low refractive index, a light-emitting element with higher external quantum efficiency can be provided.

[0358] In addition, as the electron-injecting layer 115, an organic compound of one embodiment of the present application described in Embodiment 1 can be used. In addition, the electron-injecting layer 115 can contain a substance having an electron-transporting property in addition to the organic compound of one embodiment of the present application described in Embodiment 1.

[0359] <Structure of Second Electrode> The second electrode 102 is an electrode including a cathode. The second electrode 102 can have a stacked structure, in which case a layer in contact with the organic compound layer 103 is used as the cathode. As a substance forming the cathode, a metal, an alloy, a conductive compound, and a mixture thereof having a small work function (specifically, 3.8 eV or less) can be used. As specific examples of such a cathode material, an alkali metal such as lithium (Li) or cesium (Cs), an element belonging to Group 1 or Group 2 in the periodic table, such as magnesium (Mg), calcium (Ca), or strontium (Sr), an alloy containing the above elements (MgAg, AlLi), a rare earth metal such as europium (Eu) or ytterbium (Yb), and an alloy containing the above elements can be given. However, by providing the electron-injecting layer between the second electrode 102 and the electron-transporting layer, various conductive materials such as Al, Ag, ITO, indium tin oxide containing silicon or silicon oxide, and the like can be used as the cathode regardless of the size of the work function.

[0360] In the case where the second electrode 102 is formed using a material having a transmittance for visible light, a light-emitting element which emits light from the side of the second electrode 102 can be formed.

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

[0362] The organic compound layer 103 can be formed by various methods, whether dry or wet, such as vacuum deposition, gravure printing, offset printing, screen printing, inkjet printing, or spin coating.

[0363] In addition, the above-mentioned electrodes or layers may be formed by using different deposition methods.

[0364] This embodiment mode can be appropriately combined with other embodiment modes or examples. In addition, in this specification, when a plurality of configuration examples are shown in one embodiment mode, the configuration examples can be appropriately combined.

[0365] Implementation 3 like Figure 9A and Figure 9B As shown, a plurality of light-emitting devices 130 are formed on an insulating layer 175 to form a display device. In this embodiment, a display device according to one embodiment of the present invention is described in detail.

[0366] The display device 100 includes a pixel portion 177 in which a plurality of pixels 178 are arranged in a matrix. The pixel 178 includes a sub-pixel 110R, a sub-pixel 110G, and a sub-pixel 110B.

[0367] In this specification, for example, subpixel 110 may be used to describe common features among subpixel 110R, subpixel 110G, and subpixel 110B. Other components distinguished by letters may be described using symbols without letters.

[0368] Sub-pixel 110R presents red light, sub-pixel 110G presents green light, and sub-pixel 110B presents blue light. Thus, an image can be displayed on the pixel portion 177. Note that in this embodiment, sub-pixels of three colors, red (R), green (G), and blue (B), are used as examples for explanation, and sub-pixels of other colors can also be combined. In addition, the number of sub-pixels is not limited to three, and can be four or more. As four sub-pixels, for example, there can be mentioned: sub-pixels of four colors, R, G, B, and white (W); sub-pixels of four colors, R, G, B, and yellow (Y); and four sub-pixels of R, G, B, and infrared light (IR); and the like.

[0369] In this specification and the like, 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 intersect.

[0370] exist Figure 9A In the example shown, sub-pixels of different colors are arranged in the X direction, and sub-pixels of the same color are arranged in the Y direction. Note that sub-pixels of different colors can also be arranged in the Y direction, and sub-pixels of the same color can also be arranged in the X direction.

[0371] A connection portion 140 is 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 organic compound layer 103 is provided in the region 141. The connection portion 140 is provided with a conductive layer 151C.

[0372] exist Figure 9A In the example shown, the region 141 and the connection portion 140 are located on the right side of the pixel portion 177. However, there is no particular limitation on the positions of the region 141 and the connection portion 140. Alternatively, there may be one or more regions 141 and the connection portion 140.

[0373] Figure 9B It is along Figure 9A An example of a cross-sectional view along the dotted line A1-A2 in FIG. Figure 9B As shown, display device 100 includes an insulating layer 171, a conductive layer 172 on insulating layer 171, an insulating layer 173 on insulating layer 171 and conductive layer 172, an insulating layer 174 on insulating layer 173, and an insulating layer 175 on insulating layer 174. Insulating layer 171 is provided on a substrate (not shown). Insulating layer 175, insulating layer 174, and insulating layer 173 are provided with openings that reach conductive layer 172, and plugs 176 are provided so as to fit into these openings.

[0374] In pixel portion 177, light-emitting devices 130 are provided on insulating layer 175 and plug 176. Furthermore, protective layer 135 is provided to cover light-emitting devices 130. Substrate 120 is bonded to protective layer 135 via resin layer 122. Furthermore, inorganic insulating layer 125 and insulating layer 127 on inorganic insulating layer 125 are preferably provided between adjacent light-emitting devices 130.

[0375] Figure 9B Although cross sections of the inorganic insulating layers 125 and the insulating layers 127 are shown, the inorganic insulating layers 125 and 127 are preferably formed as a continuous layer when viewing the display device 100 from above. In other words, the inorganic insulating layers 125 and 127 are preferably insulating layers having openings above the first electrodes.

[0376] Figure 9BThe light-emitting device 130R, the light-emitting device 130G, and the light-emitting device 130B are shown as the light-emitting device 130. The light-emitting device 130R, the light-emitting device 130G, and the light-emitting device 130B emit light of different colors from each other. For example, the light-emitting device 130R can emit red light, the light-emitting device 130G can emit green light, and the light-emitting device 130B can emit blue light. Alternatively, the light-emitting device 130R, the light-emitting device 130G, or the light-emitting device 130B can emit other visible light or infrared light.

[0377] The display device of one embodiment of the present application can have a top emission structure (top emission structure) in which light is emitted to the opposite direction of the substrate on which the light-emitting device is formed. Alternatively, the display device of one embodiment of the present application can have a bottom emission structure (bottom emission structure).

[0378] As the light-emitting substance included in the light-emitting device 130, for example, an organic compound or an organometallic complex such as a substance (fluorescent material) that emits fluorescent light, a substance (phosphorescent material) that emits phosphorescent light, and a substance (Thermally activated delayed fluorescence (TADF) material) that exhibits thermally activated delayed fluorescence can be given. Alternatively, an inorganic compound such as a quantum dot can be used.

[0379] The light-emitting device 130R has a structure as described in Embodiment 1. The light-emitting device 130R includes a first electrode (pixel electrode) including the conductive layer 151R and the conductive layer 152R, the organic compound layer 103R over the first electrode, the common layer 104 over the organic compound layer 103R, and the second electrode (common electrode) 102 over the common layer. Note that the common layer 104 can be provided or not be provided, but in the case where the common layer 104 is provided, damage to the organic compound layer 103R at the time of processing can be reduced, and thus the common layer 104 is preferably provided. In the case where the common layer 104 is provided, the common layer 104 is preferably an electron-injection layer. In the case where the common layer 104 is not provided, the organic compound layer 103R corresponds to the organic compound layer 103 in Embodiment 1 and Embodiment 2. In the case where 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 Embodiment 1 and Embodiment 2.

[0380] The light-emitting device 130G has a structure as shown in Embodiment 1. The light-emitting device 130G includes a first electrode (pixel electrode) composed of the conductive layer 151G and the conductive layer 152G, the organic compound layer 103G over the first electrode, the common layer 104 over the organic compound layer 103G, and a second electrode (common electrode) 102 over the common layer. Note that the common layer 104 can be provided or not be provided, but when the common layer 104 is provided, damage to the organic compound layer 103G at the time of processing can be reduced, and thus the common layer 104 is preferably provided. Further, in the case where the common layer 104 is not provided, the organic compound layer 103G corresponds to the organic compound layer 103 in Embodiments 1 and 2. In the case where 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 a structure as shown in Embodiment 1. The light-emitting device 130B includes a first electrode (pixel electrode) composed of the conductive layer 151B and the conductive layer 152B, the organic compound layer 103B over the first electrode, the common layer 104 over the organic compound layer 103B, and a second electrode (common electrode) 102 over the common layer. Note that the common layer 104 can be provided or not be provided, but when the common layer 104 is provided, damage to the organic compound layer 103B at the time of processing can be reduced, and thus the common layer 104 is preferably provided. Further, in the case where the common layer 104 is not provided, the organic compound layer 103B corresponds to the organic compound layer 103 in Embodiments 1 and 2. In the case where 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 included in the light-emitting device is used as an anode, and the other is used as a cathode. Hereinafter, description is made on the assumption that the pixel electrode is used as an anode and the common electrode is used as a cathode, unless specifically stated.

[0383] The organic compound layer 103R, the organic compound layer 103G, and the organic compound layer 103B are independently island-shaped for each device or for each emission 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 in a high-definition display device. Thus, a display device with extremely high contrast can be realized by preventing crosstalk. In particular, a display device with high current efficiency at low luminance 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 technique.

[0385] In addition, 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. Figure 9B In the example shown, the first electrode of the light-emitting device 130 has a stacked structure of a conductive layer 151 (151R, 151G, 151B) and a conductive layer 152 (152R, 152G, 152B). For example, when the display device 100 has a top emission structure and the pixel electrode of the light-emitting device 130 is used as an anode, the conductive layer 151 is preferably a layer with high visible light reflectivity, and the conductive layer 152 is preferably a layer with, for example, visible light transmittance and a large work function. When the display device 100 has a top emission structure, the higher the visible light reflectivity of the pixel electrode, the higher the extraction efficiency of light emitted by the organic compound layer 103. In addition, when the pixel electrode is used as an anode, the greater the work function of the pixel electrode, the easier it is to inject holes into the organic compound layer 103. Thus, by having the pixel electrode of the light-emitting device 130 have a stacked structure of a conductive layer 151 with high visible light reflectivity and a conductive layer 152 with a large work function, the light-emitting device 130 can be a light-emitting device with high light extraction efficiency and low driving voltage. Note that in this specification and the like, when describing common features among 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 conductive layer 151 is a layer having a high visible light reflectivity, the visible light reflectivity of conductive layer 151 is preferably, for example, 40% to 100% or 70% to 100%. Furthermore, when conductive layer 152 is an electrode having visible light transmittance, the visible light transmittance is preferably, for example, 40% or more.

[0387] Here, when the pixel electrode has a multi-layer stacked structure, the pixel electrode may be degraded due to reactions between the layers. For example, when removing a film formed after forming the pixel electrode by wet etching, galvanic corrosion may occur due to contact of the chemical solution with the pixel electrode.

[0388] Thus, in the display device 100 of this embodiment, the insulating layers 156 (156R, 156G, 156B) are formed on the side surfaces of the conductive layers 151 and 152. Thus, for example, even in the case where a film formed after the pixel electrode including the conductive layers 151 and 152 is removed by a wet etching method is in contact with the conductive layer 151, the conductive layer 151 can be prevented from being in contact with the liquid medicine. Thus, for example, galvanic corrosion in the pixel electrode can be prevented. Thus, the display device 100 can be manufactured by a method with a high yield, and thus a low-cost display device can be realized. Further, a defect in the display device 100 can be prevented, and thus the display device 100 can be a display device with high reliability. Note that in this specification and the like, when contents common to the insulating layers 156R, 156G, and 156B are described, they are sometimes referred to as the insulating layers 156 and described.

[0389] As the conductive layer 151, for example, a metal material can be used. Specifically, for example, a metal 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), or an alloy of any of these metals can be used.

[0390] As the conductive layer 152, an oxide containing one or more selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon can be used. For example, it is preferable to use a conductive oxide containing one or more of 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, 4.0 eV or more, and thus is suitably used as the conductive layer 152.

[0391] Each of the conductive layers 151 and 152 can have a stacked structure of a plurality of layers containing different materials. In this case, the conductive layer 151 can include a layer using a material that can be used for the conductive layer 152 such as a conductive oxide, and the conductive layer 152 can include a layer using a material that can be used for the conductive layer 151 such as a metal material. For example, in the case where 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 using a material that can be used for the conductive layer 152.

[0392] Next, with reference to 10A to 15C A display device 100 having Figure 9AAn example of a manufacturing method of the display device 100 of the illustrated structure will be described. In the light-emitting element included in the display device 100, an organic layer is formed through a manufacturing process including a process using water. By the light-emitting element included in the display device of one embodiment of the present application using the light-emitting element of one embodiment of the present application, a display device including a light-emitting element with a reduced driving voltage and high emission efficiency can be provided.

[0393] [Example of Manufacturing Method] A thin film (an insulating film, a semiconductor film, a conductive film, or the like) constituting a display device can be formed by a sputtering method, a chemical vapor deposition (CVD) method, a vacuum evaporation method, a pulsed laser deposition (PLD) method, or an atomic layer deposition (ALD) method. As the CVD method, there are a plasma-enhanced CVD (PECVD) method and a thermal CVD method. As one of the thermal CVD methods, there is a metal organic CVD (MOCVD) method.

[0394] Further, a thin film (an insulating film, a semiconductor film, a conductive film, or the like) constituting a display device can be formed by a wet deposition method such as a spin coating method, an immersion method, a spray coating method, an inkjet method, a dispenser method, a screen printing method, an offset printing method, a doctor knife method, a slit coating method, a roll coating method, a curtain coating method, or a blade coating method.

[0395] In particular, when a light-emitting element is manufactured, a vacuum process such as an evaporation method and a solution process such as a spin coating method or an inkjet method can be used. As the evaporation method, a physical vapor deposition method (PVD method) such as a sputtering method, an ion plating method, an ion beam evaporation method, a molecular beam evaporation method, or a vacuum evaporation method, and a chemical vapor deposition method (CVD method) can be given. In particular, a functional layer included in an organic compound layer (a hole-injection layer, a hole-transport layer, a hole-blocking layer, a light-emitting layer, an electron-blocking layer, an electron-transport layer, an electron-injection layer, or the like) can be formed by an evaporation method (a vacuum evaporation method or the like), a coating method (an immersion coating method, a dye coating method, a bar coating method, a spin coating method, a spray coating method, or the like), a printing method (an inkjet method, a screen printing (hole printing) method, an offset printing (planographic printing) method, a flexographic printing (holographic printing) method, a photogravure printing method, or a microcontact printing method), or the like.

[0396] Further, when the thin film constituting the display device is processed, the processing can be performed using, for example, a lithography technique. Alternatively, the thin film can be processed using a nanoimprint method, a sandblasting method, a lift-off method, or the like. Further, the island-shaped thin film can be directly formed by a deposition method using a metal mask or the like as a shielding mask.

[0397] As the lithography technique, for example, a photolithography method can be used. The photolithography method typically has two 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 etching, and the resist mask is removed. The other is a method in which a thin film having photosensitivity is formed, exposure and development are performed, and the thin film is processed into a desired shape.

[0398] In the photolithography method, as light for exposure, for example, i-line (wavelength: 365 nm), g-line (wavelength: 436 nm), h-line (wavelength: 405 nm), or light obtained by mixing these lights can be used. In addition, ultraviolet light, KrF laser light, or ArF laser light, or the like can be used. Further, exposure can be performed using a liquid immersion exposure technique. Further, as light for exposure, extreme ultraviolet (EUV) light or X-ray can be used. Further, instead of light for exposure, an electron beam can be used. When extreme ultraviolet light, X-ray, or an electron beam is used, extremely fine processing can be performed, and thus is preferable. In addition, when exposure is performed by scanning of a light beam such as an electron beam, a photomask is not needed.

[0399] In etching of the thin film, a dry etching method, a wet etching method, or a sandblasting method, or the like can be used.

[0400] In addition, in a manufacturing process of the light emitting device, an organic compound excited by absorbing light is used. The excited organic compound sometimes has a high possibility of reacting with oxygen or water in the atmosphere. In other words, when light of a wavelength absorbed by the organic compound is irradiated in the presence of oxygen, the organic compound sometimes generates a degradation product.

[0401] Thus, when a substrate on which the organic compound is formed is processed using a photolithography method, in a case where exposure to the atmosphere is performed, it is preferable to perform the above processing in an environment in which illumination is appropriately controlled. It is ideal to perform the above processing in an environment in which illumination of a wavelength that does not excite the organic compound excited by absorbing light is used, but in order to secure an illuminance or color rendering property to a degree in which work efficiency is not reduced, it is preferable to use illumination in which an emission end at a shortest wavelength in an emission spectrum of a light source is 600 nm or less, and preferably 580 nm or less.

[0402] For example, as the illumination, a yellow lamp (fluorescent lamp or light emitting diode (LED)) which does not emit light of a wavelength shorter than 500 nm is preferably used. Further, an orange lamp (fluorescent lamp or light emitting diode (LED)) which does not emit light of a wavelength shorter than 530 nm is preferably used. Further, a low-pressure sodium lamp can also be used. Further, an illumination using an optical filter capable of shielding light located in a short wavelength, such as an incandescent lamp, fluorescent lamp, light emitting diode (LED), halogen lamp, sunlight can be used. As the optical filter capable of shielding light located in a short wavelength, a band-pass filter, long-pass filter (short wavelength cut filter) can be used, for example. In addition, by using the above illumination, the illuminance of the illumination light can be reduced.

[0403] First, as shown in FIG. 10A, an insulating layer 171 is formed on a substrate (not shown). Next, a conductive layer 172 and a conductive layer 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 layer 172 and the conductive layer 179. Next, an insulating layer 174 is formed on the insulating layer 173, and an insulating layer 175 is formed on the insulating layer 174. Figure 10A

[0404] As the substrate, a substrate having at least heat resistance capable of withstanding the following heat treatment can be used. In the case where an insulating substrate is used as the substrate, a glass substrate, quartz substrate, sapphire substrate, ceramic substrate, or organic resin substrate, or the like can be used. Further, a single crystal semiconductor substrate or a polycrystal semiconductor substrate using silicon or silicon carbide, or the like as a material, a compound semiconductor substrate using silicon germanium, or the like as a material, an SOI substrate, or the like semiconductor substrate can also be used.

[0405] Next, as shown in FIG. 10A, an opening reaching the conductive layer 172 is formed in the insulating layer 175, the insulating layer 174, and the insulating layer 173. Next, a plug 176 is formed so as to be embedded in the opening.

[0406] Next, as shown in FIG. 10A, an opening reaching the conductive layer 172 is formed in the insulating layer 175, the insulating layer 174, and the insulating layer 173. Next, a plug 176 is formed so as to be embedded in the opening. Figure 10A

[0407] Next, as shown in FIG. 10A, an opening reaching the conductive layer 172 is formed in the insulating layer 175, the insulating layer 174, and the insulating layer 173. Next, a plug 176 is formed so as to be embedded in the opening. Figure 10A ​​As shown, a conductive film 152f which will later become the conductive layer 152R, the conductive layer 152G, the conductive layer 152B, and the conductive layer 152C is formed over the conductive film 151f. The conductive film 152f can be formed using, for example, a sputtering method or a vacuum evaporation method. As the conductive film 152f, a conductive oxide can be used, for example. Alternatively, a stacked structure of a film using a metal material and a film using a conductive oxide over the film can be employed as the conductive film 152f. For example, a stacked structure of a film using titanium, silver, or an alloy containing silver and a film using a conductive oxide over the film can be employed as the conductive film 152f.

[0408] Further, the conductive film 152f can be formed using an ALD method. Here, as the conductive film 152f, an oxide film containing one or more selected from indium, tin, zinc, gallium, titanium, aluminum, and silicon can be used. At this time, the conductive film 152f can be formed by repeating a cycle of introduction of a precursor (which is sometimes referred to as a precursor or a metal precursor, etc.), purge of the precursor, introduction of an oxidizing agent (which is sometimes referred to as a reactant, a reactant, or a non-metal precursor, etc.), and purge of the oxidizing agent. Here, when an oxide film containing a plurality of metals such as indium tin oxide is formed as the conductive film 152f, the metal composition can be controlled by changing the number of cycles depending on the kind of the precursor.

[0409] For example, in the case of depositing an indium tin oxide film as the conductive film 152f, an In-O film is formed by purging a precursor containing indium after the introduction of the precursor and introducing an oxidizing agent, and then a Sn-O film is formed by purging a precursor containing tin after the introduction of the precursor and introducing an oxidizing agent. Here, by making the number of cycles at the time of forming the In-O film larger than the number of cycles at the time of 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] Further, for example, in the case of depositing a zinc oxide film as the conductive film 152f, a Zn-O film is formed by the above process. Further, for example, in the case of depositing an aluminum zinc oxide film as the conductive film 152f, a Zn-O film and an Al-O film are formed by the above process. Further, for example, in the case of depositing a titanium oxide film as the conductive film 152f, a Ti-O film is formed by the above process. Further, for example, in the case of depositing an indium tin oxide film containing silicon as the conductive film 152f, an In-O film, a Sn-O film, and a Si-O film are formed by the above process. Further, for example, in the case of depositing a zinc oxide film containing gallium, a Ga-O film and a Zn-O film are formed by the above process.

[0411] As a precursor containing indium, for example, triethylindium, trimethylindium or [1,1,1-trimethyl-N-(trimethylsilyl)amide]-indium can be used. As a precursor containing tin, for example, tin chloride or tetrakis(dimethylamide)tin can be used. As a precursor containing zinc, for example, diethylzinc or dimethylzinc can be used. As a precursor containing gallium, for example, triethylgallium can be used. As a precursor containing titanium, for example, titanium chloride, tetrakis(dimethylamide)titanium or tetraisopropyl titanate can be used. As a precursor containing aluminum, for example, aluminum chloride or trimethylaluminum can be used. As a precursor containing silicon, for example, trisilylamine, bis(diethylamino)silane, tris(dimethylamino)silane, bis(tert-butylamino)silane or bis(ethylmethylamino)silane can be used. In addition, as an oxidizing agent, water vapor, oxygen plasma or ozone gas can be used.

[0412] Then, if Figure 10A As shown in FIG. 1 , a resist mask 191 is formed on the conductive film 151f and the conductive film 152f. The resist mask 191 can be formed by applying a photosensitive material (photoresist), exposing the material to light, and developing the material.

[0413] Then, if Figure 10B As shown, the conductive film 151f and the conductive film 152f in the region not overlapping 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 made of a conductive oxide such as indium tin oxide, this layer can also be removed by wet etching. Thus, the conductive layers 151 and 152 are formed. Note that, for example, when a portion of the conductive film 151f is removed by dry etching, a recess may be formed in the region of the insulating layer 175 that does not overlap with the conductive layer 151.

[0414] Note that after the conductive film 152f is processed using lithography to form the conductive layers 152R, 152G, 152B, and 152C, 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, a portion of the conductive film 152f may be removed using etching. For example, the conductive film 152f may be removed using wet etching. Note that dry etching may also be used to remove the conductive film 152f. Subsequently, the conductive film 151f is preferably removed using wet etching.

[0415] Here, it is preferable to perform a hydrophobic treatment on the conductive layer 152. The hydrophobic treatment can change the surface state of the treatment object from hydrophilic to hydrophobic, or can improve the hydrophobicity of the surface of the treatment object. The hydrophobic treatment of the conductive layer 152 can improve the adhesion between the conductive layer 152 and the organic compound layer 103 to be formed in a subsequent step, thereby suppressing film peeling. Note that the hydrophobic treatment can also be omitted.

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

[0417] Then, if Figure 10D As shown, an insulating film 156f, which will later become insulating layers 156R, 156G, 156B, and 156C, is formed on conductive layers 151R and 152R, conductive layers 151G and 152G, conductive layers 151B and 152B, conductive layers 151C and 152C, and insulating layer 175. Insulating film 156f can be formed by, for example, CVD, ALD, sputtering, or vacuum evaporation.

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

[0419] Then, if Figure 10E As shown, insulating film 156f is processed to form insulating layer 156R, insulating layer 156G, insulating layer 156B, and insulating layer 156C. For example, insulating layer 156 can be formed by etching the top surface of insulating film 156f substantially uniformly. This process of planarizing by uniform etching is also called etch-back. Alternatively, insulating layer 156 can be formed using lithography.

[0420] Then, if Figure 11A As shown in FIG. 1 , an organic compound film 103Rf, which will later become the organic compound layer 103R, is formed over 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] like Figure 11A As shown, the organic compound film 103Rf is not formed on the conductive layer 152C. For example, by using a mask for defining the deposition range (also referred to as an area mask or a rough metal mask to distinguish it from a high-definition metal mask), the organic compound film 103Rf can be deposited only in the desired area. By adopting a deposition process using an area mask and a processing process using a resist mask, a light-emitting device can be manufactured using a relatively simple process.

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

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

[0424] Note that in this embodiment, an example is shown in which the mask film is composed of a two-layer structure consisting of the sacrificial film 158Rf and the mask film 159Rf. However, the mask film may have a single-layer structure or a stacked-layer structure having three or more layers. Furthermore, in this specification and other documents, the mask layer may also 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 having high resistance to the processing conditions of the organic compound film 103Rf, specifically, a film having a large etching selectivity with the organic compound film 103Rf. The mask film 159Rf is made of a film having a large etching selectivity with the sacrificial film 158Rf.

[0427] Furthermore, the sacrificial film 158Rf and the mask film 159Rf are formed at a temperature lower than the heat resistance temperature of the organic compound film 103Rf. The substrate temperature during formation of the sacrificial film 158Rf and the sacrificial film 159Rf is typically 200°C or lower, preferably 150°C or lower, more preferably 120°C or lower, further preferably 100°C or lower, and even more preferably 80°C or lower.

[0428] As the sacrificial film 158Rf and the mask film 159Rf, a film that can be removed by a wet etching method is preferably used. By using a wet etching method, damage to the organic compound film 103Rf in processing of the sacrificial film 158Rf and the mask film 159Rf can be reduced as compared to the case of using a dry etching method.

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

[0430] Further, the sacrificial film 158Rf formed in contact with the organic compound film 103Rf is preferably formed by a formation method that causes less damage to the organic compound film 103Rf than the formation of the mask film 159Rf. For example, it is more preferable to form the sacrificial film 158Rf by an ALD method or a vacuum evaporation method than by a sputtering method.

[0431] As the sacrificial film 158Rf and the mask film 159Rf, one or more of a metal film, an alloy film, a metal oxide film, a semiconductor film, an organic insulating film, and an inorganic insulating film, for example, can be used.

[0432] As the sacrificial film 158Rf and the mask film 159Rf, a metal material such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, and tantalum, or an alloy material containing the metal material, for example, can be used. It is particularly preferable to use a low-melting-point material such as aluminum or silver. By using a metal material capable of shielding ultraviolet rays as one or both of the sacrificial film 158Rf and the mask film 159Rf, irradiation of ultraviolet rays to the organic compound film 103Rf can be suppressed, and thus deterioration of the organic compound film 103Rf can be suppressed, which is preferable.

[0433] Further, as the sacrificial film 158Rf and the mask film 159Rf, a metal oxide such as an In-Ga-Zn oxide, indium oxide, an In-Zn oxide, an In-Sn oxide, an indium titanium oxide (In-Ti oxide), an indium tin zinc oxide (In-Sn-Zn oxide), an indium titanium zinc oxide (In-Ti-Zn oxide), an indium gallium tin zinc oxide (In-Ga-Sn-Zn oxide), an indium tin oxide containing silicon, or the like can be used.

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

[0435] Further, as the sacrificial film and the mask film, a film including a material having light blocking properties, particularly ultraviolet light blocking properties, is preferably used. As the material having light blocking properties, various materials such as a metal, an insulator, a semiconductor, and a semimetal having ultraviolet light blocking properties can be used. Since part or all of the sacrificial film and the mask film will be removed in a later step, the sacrificial film and the mask film are preferably a film that can be processed by etching, particularly a film with good processability.

[0436] When a semiconductor material such as silicon or germanium is used as the sacrificial film and the mask film, the material has high affinity with the manufacturing process of a semiconductor, and thus is preferable. Alternatively, an oxide or a nitride of the above semiconductor material can be used. Alternatively, a nonmetal material such as carbon or a compound thereof can be used. Further, a metal such as titanium, tantalum, tungsten, chromium, aluminum, or an alloy including one or more of them can be used. Further, an oxide including the above metal such as titanium oxide or chromium oxide, or a nitride such as titanium nitride, chromium nitride, or tantalum nitride can be used.

[0437] Further, by using a film including a material having ultraviolet light blocking properties as the sacrificial film or the mask film, ultraviolet light irradiation to the organic compound layer in the exposure step, for example, can be suppressed. By suppressing damage to the organic compound layer by ultraviolet light, the reliability of the light-emitting device can be improved.

[0438] Note that a film including a material having ultraviolet light blocking properties also has the same effect when used as a material of an inorganic insulating film 125f to be described later.

[0439] Further, each of the sacrificial film 158Rf and the mask film 159Rf can be formed using various inorganic insulating films. In particular, an oxide insulating film has higher adhesiveness to the organic compound film 103Rf than a nitride insulating film, and thus is preferable. For example, an inorganic insulating material such as aluminum oxide, hafnium oxide, or silicon oxide can be used for the sacrificial film 158Rf and the mask film 159Rf. As each of the sacrificial film 158Rf and the mask film 159Rf, an aluminum oxide film can be formed by an ALD method, for example. By using the ALD method, damage to the substrate, particularly the organic compound layer, can be reduced, and thus is preferable.

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

[0441] In addition, the same inorganic insulating film can be used for both the sacrificial layer 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 layer 158Rf and the inorganic insulating layer 125. Here, the sacrificial layer 158Rf and the inorganic insulating layer 125 can be deposited under the same deposition conditions or different deposition conditions. For example, by depositing the sacrificial film 158Rf under the same conditions as the inorganic insulating layer 125, the sacrificial film 158Rf can be formed as an insulating layer with high barrier properties against at least one of water and oxygen. On the other hand, the sacrificial film 158Rf is a layer that will be mostly or entirely removed in a subsequent step, so it is preferably easy to process. Therefore, the sacrificial layer 158Rf is preferably deposited under conditions where the substrate temperature is lower than that of the inorganic insulating layer 125 during deposition.

[0442] Organic materials may be used for either or both of the sacrificial film 158Rf and the mask film 159Rf. For example, the organic material may be soluble in a solvent that is chemically stable to at least the film located on the uppermost portion of the organic compound film 103Rf. In particular, materials that are soluble in water or alcohol are suitable. When depositing these materials, it is preferred to apply the material by a wet deposition method while dissolving it in a solvent such as water or alcohol, followed by a heat treatment to evaporate the solvent. In this case, the heat treatment is preferably performed in a reduced pressure atmosphere, as this allows the solvent to be removed at a low temperature and in a short time, thereby minimizing 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, polyvinyl pyrrolidone, polyethylene glycol, polyglycerol, pullulan, water-soluble cellulose, alcohol-soluble polyamide resin, or fluororesin such as perfluoropolymer.

[0444] For example, an organic film (eg, a PVA film) formed using any of the evaporation method and the above-described wet deposition method may be used as the sacrificial film 158Rf, and an inorganic film (eg, a silicon nitride film) formed using a sputtering method may be used as the mask film 159Rf.

[0445] Then, if Figure 11A As shown in FIG. 1 , a resist mask 190R is formed on the mask film 159Rf. The resist mask 190R can be formed by applying a photosensitive material (photoresist), exposing it to light, and developing it.

[0446] The resist mask 190R may use a positive resist material or a negative resist material.

[0447] The resist mask 190R is provided so as to overlap with the conductive layer 152R. The resist mask 190R is preferably also provided so as to overlap with the conductive layer 152C. Thus, the conductive layer 152C can be prevented from being damaged in the manufacturing process of the display device. Note that the resist mask 190R can not be provided over the conductive layer 152C. In addition, as Figure 11A As illustrated in a cross-sectional view between B1 and B2, the resist mask 190R is preferably provided so as to cover the end portion of the organic compound film 103Rf to the end portion of the conductive layer 152C (the end portion on the side of the organic compound film 103Rf).

[0448] Next, as illustrated in FIG. 17B, a portion of the mask film 159Rf is removed using the resist mask 190R, whereby the mask layer 159R is formed. The mask layer 159R remains over the conductive layer 152R and the conductive layer 152C. Then, the resist mask 190R is removed. Next, a portion of the sacrificial film 158Rf is removed using the mask layer 159R as a mask (also referred to as a hard mask), whereby the sacrificial layer 158R is formed. Figure 11B

[0449] The sacrificial film 158Rf and the mask film 159Rf can each be processed by a wet etching method or a dry etching method. The processing of the sacrificial film 158Rf and the mask film 159Rf is preferably performed by isotropic etching.

[0450] By using a wet etching method, damage to the organic compound film 103Rf in the processing of the sacrificial film 158Rf and the mask film 159Rf can be reduced, as compared to the case of using a dry etching method. In the case of using a wet etching method, for example, a developer, an aqueous solution of tetramethylammonium hydroxide (TMAH), dilute hydrofluoric acid, oxalic acid, phosphoric acid, acetic acid, nitric acid, or a mixed liquid thereof is preferably used.

[0451] Since the organic compound film 103Rf is not exposed in the processing of the mask film 159Rf...

Claims

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

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

3. A light-emitting device comprising: a first electrode; a second electrode; a first light-emitting layer; and a first layer, wherein the first light-emitting layer is positioned between the first electrode and the second electrode, the first layer is positioned between the first light-emitting layer and the second electrode, the first layer contains at least one of a metal and a metal compound, a first organic compound, and a second organic compound, and a wavelength of an absorption edge on a long wavelength side of an absorption spectrum of a mixed film containing 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 a wavelength of an absorption edge on a long wavelength side of an absorption spectrum of a single film of the first organic compound and a wavelength of an absorption edge on a long wavelength side of an absorption spectrum of a single film of the second organic compound. a second light-emitting layer between the first layer and the second electrode. a second light-emitting layer between the first layer and the second electrode. a second light-emitting layer between the first layer and the second electrode.

7. The light-emitting device according to claim 1, further comprising: a second layer between the first layer and the second electrode, wherein the second layer contains 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, and the fourth organic compound has at least one of a halogen group and a cyano group.

8. The light-emitting device according to claim 1, wherein a LUMO level of the first organic compound is higher than a LUMO level of the second organic compound.

9. The light-emitting device according to claim 1, wherein a HOMO level of the first organic compound is higher than a HOMO level of the second organic compound. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 4. The light emitting device of claim 1, further comprising: ​ 5. The light emitting device of claim 2, further comprising: ​ 6. The light emitting device of claim 3, further comprising: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 10. The light-emitting device according to claim 1, wherein the first organic compound and the second organic compound each have a heteroaromatic ring.

11. The light-emitting device according to claim 10, wherein the heteroaromatic ring of the first organic compound and the heteroaromatic ring of the second organic compound each independently have 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. The light-emitting device according to claim 10, wherein the first organic compound has an electron-donating group.

13. The light-emitting device according to claim 12, 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. The light-emitting device according to claim 1, wherein the metal and the metal compound include a metal belonging to Group 1, Group 3, Group 11, or Group 13 in the periodic table.

15. The light-emitting device according to claim 2, wherein the LUMO level of the first organic compound is higher than the LUMO level of the second organic compound.

16. The light-emitting device according to claim 2, wherein the HOMO level of the first organic compound is higher than the HOMO level of the second organic compound.

17. The light-emitting device according to claim 2, wherein the first organic compound and the second organic compound each have a heteroaromatic ring.

18. The light-emitting device according to claim 3, wherein the LUMO level of the first organic compound is higher than the LUMO level of the second organic compound.

19. The light-emitting device according to claim 3, wherein the HOMO level of the first organic compound is higher than the HOMO level of the second organic compound.

20. The light-emitting device according to claim 3, wherein the first organic compound and the second organic compound each have a heteroaromatic ring.

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