Light-emitting element, light-emitting device, electronic device, and lighting device

Abstract

Provided is a light-emitting element with a low driving voltage and high reliability. The light-emitting element includes an electron injection layer between a cathode and a light-emitting layer. The electron injection layer is a mixed film of a metal and an organic compound having a function of interacting with the metal at 3 or 4 teeth, and a SOMO is formed by a metal atom and the organic compound.

Description

Technical Field

[0001] One aspect of the present invention is a novel light-emitting element including an electron injection layer. Further, one aspect of the present invention is a display device, an electronic device, and a lighting device including the light-emitting element.

[0002] Note that one aspect of the present invention is not limited to the above technical field. One aspect of the invention disclosed in this specification etc. relates to an object, a method, or a manufacturing method. Further, one aspect of the present invention relates to a process, a machine, a manufacture, or a composition of matter. Therefore, specifically, examples of the technical field of one aspect of the present invention disclosed in this specification may include semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, lighting devices, power storage devices, storage devices, driving methods of these devices, and manufacturing methods of these devices. Background Art

[0003] In recent years, research and development of light-emitting elements using electroluminescence (EL) have been increasingly active. The basic structure of these light-emitting elements is a structure in which a layer containing a light-emitting substance (EL layer) is sandwiched between a pair of electrodes. By applying a voltage between the electrodes of the element, light emission from the light-emitting substance can be obtained.

[0004] Since the above light-emitting element is a self-luminous type light-emitting element, a display device using the light-emitting element has advantages such as good visibility, no need for a backlight, and low power consumption. Further, the display device also has the following advantages: it can be manufactured thin and light; and has a fast response speed etc.

[0005] Generally, in an EL element, in order to reduce the driving voltage, an electron injection layer is provided between the cathode and the light-emitting layer. In order to reduce the injection barrier of electrons between the cathode and the EL layer, as the electron injection layer, a metal having a small work function such as an alkali metal or an alkaline earth metal represented by lithium (Li) or calcium (Ca), or a compound of these metals (for example, Patent Document 1) is used.

[0006] [Prior Art Documents]

[0007] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-102175 Summary of the Invention

[0009] Technical Problem to be Solved by the Invention

[0010] Metals with a small work function or compounds of these metals have a high reactivity with oxygen or water and are not easily processed. In addition, when the metal or the metal compound is used in a light-emitting element, it is affected by oxygen or water, and sometimes a decrease in the luminous efficiency of the light-emitting element, an increase in the driving voltage, or a decrease in reliability may occur. Therefore, it is necessary to develop an electron injection layer that is not easily affected by oxygen or water and has a small electron injection barrier between the cathode and the EL layer.

[0011] In view of the above problems, an object of one aspect of the present invention is to provide a light-emitting element with a low driving voltage. An object of one aspect of the present invention is to provide a light-emitting element with high moisture resistance. An object of one aspect of the present invention is to provide a light-emitting element with high oxygen resistance. An object of one aspect of the present invention is to provide a light-emitting element with reduced power consumption. An object of one aspect of the present invention is to provide a light-emitting element with high reliability. An object of one aspect of the present invention is to provide a novel light-emitting element. An object of one aspect of the present invention is to provide a novel semiconductor device. An object of one aspect of the present invention is to provide an organic compound that can be used in a light-emitting element with high moisture resistance.

[0012] An object of one aspect of the present invention is to provide an electronic device and a lighting device with high moisture resistance using the above light-emitting element. An object of one aspect of the present invention is to provide a light-emitting device with reduced power consumption using the above light-emitting element. An object of one aspect of the present invention is to provide a light-emitting device with a long service life using the above light-emitting element.

[0013] Note that the description of the above objects does not preclude the existence of other objects. One aspect of the present invention does not necessarily need to achieve all of the above objects. In addition, objects other than the above can be known and extracted from the description of the specification and the like.

[0014] Means for Solving Technical Problems

[0015] As described above, the development of a light-emitting element that is required to have both high moisture resistance and electron injection characteristics. Therefore, the development of a light-emitting element that does not use a metal with a small work function is required.

[0016] Therefore, one aspect of the present invention is a light-emitting element including a light-emitting layer between an anode and a cathode and a first layer between the light-emitting layer and the cathode. The first layer contains a first organic compound and a metal, the metal belonging to any one of Groups 3 to 13 in the periodic table. The first organic compound includes a substituted or unsubstituted heteroaromatic ring having 1 or more and 30 or less carbon atoms, the heteroaromatic ring containing nitrogen. The nitrogen in the first organic compound has a function of interacting with the metal in a tridentate or tetradentate manner, and the first organic compound and the metal form a SOMO (Single Occupied Molecular Orbital).

[0017] Another aspect of the present invention is a light-emitting element including a first light-emitting unit and a second light-emitting unit between an anode and a cathode, and a first layer between the first light-emitting unit and the second light-emitting unit. The first layer contains a first organic compound and a metal, the metal belonging to any one of Groups 3 to 13 in the periodic table. The first organic compound includes a substituted or unsubstituted heteroaromatic ring having 1 or more and 30 or less carbon atoms, the heteroaromatic ring containing nitrogen. Nitrogen in the first organic compound has a function of interacting with the metal in a tridentate or tetradentate manner, and the first organic compound and the metal form a SOMO.

[0018] In the above structure, the first organic compound is preferably an organic compound represented by the general formula (G0).

[0019] [Chemical formula 1]

[0020]

[0021] In the general formula (G0), A 1 , A 2 and A 3 each independently represent a substituted or unsubstituted heteroaromatic ring having 1 or more and 30 or less carbon atoms. A 1 , A 2 and A 3 may also form a fused ring with each other.

[0022] In the above structure, the first organic compound is preferably an organic compound represented by the general formula (G1).

[0023] [Chemical formula 2]

[0024]

[0025] In the general formula (G1), X 1 to X 6 each independently represent carbon (C) or nitrogen (N). Carbon includes hydrogen, an alkyl group having 1 to 4 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 or more and 25 or less carbon atoms, or a substituted or unsubstituted heteroaryl group having 3 or more and 30 or less carbon atoms. R 1 to R 4 each independently represent hydrogen, an alkyl group having 1 to 4 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 or more and 25 or less carbon atoms, or a substituted or unsubstituted heteroaryl group having 3 or more and 30 or less carbon atoms. Ar represents hydrogen, an alkyl group having 1 to 4 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, an aryl group having 6 or more and 60 or less carbon atoms, or a heteroaryl group having 2 or more and 60 or less carbon atoms.

[0026] In the above structure, the first organic compound is preferably an organic compound represented by the general formula (G2).

[0027] [Chemical formula 3]

[0028]

[0029] In the general formula (G2), X 1 and X 2 each independently represents carbon (C) or nitrogen (N). Carbon includes hydrogen, an alkyl group having 1 to 4 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 or more and 25 or less carbon atoms, or a substituted or unsubstituted heteroaryl group having 3 or more and 30 or less carbon atoms. R 1 to R 8 each independently represents hydrogen, an alkyl group having 1 to 4 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 or more and 25 or less carbon atoms, or a substituted or unsubstituted heteroaryl group having 3 or more and 30 or less carbon atoms. Ar represents hydrogen, an alkyl group having 1 to 4 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, an aryl group having 6 or more and 60 or less carbon atoms, or a heteroaryl group having 2 or more and 60 or less carbon atoms.

[0030] In the above structure, the first organic compound is preferably an organic compound represented by any one of the general formulas (G3-1) to (G3-3).

[0031] [Chemical formula 4]

[0032]

[0033] In the general formulas (G3-1) to (G3-3), R 1 to R 8 each independently represents hydrogen, an alkyl group having 1 to 4 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 or more and 25 or less carbon atoms, or a substituted or unsubstituted heteroaryl group having 3 or more and 30 or less carbon atoms. Ar represents hydrogen, an alkyl group having 1 to 4 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, an aryl group having 6 or more and 60 or less carbon atoms, or a heteroaryl group having 2 or more and 60 or less carbon atoms.

[0034] In the above structure, the first organic compound is preferably an organic compound represented by any one of the general formulas (G4-1) to (G4-3).

[0035] [Chemical formula 5]

[0036]

[0037] In general formulas (G4-1) to (G4-3), Ar represents hydrogen, an alkyl group having 1 to 4 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, an aryl group having 2 or more and 60 or less carbon atoms, or a heteroaryl group having 2 or more and 60 or less carbon atoms.

[0038] In the above structure, the first organic compound is preferably an organic compound represented by any one of the following structural formulas (100) to (103).

[0039] [Chemical formula 6]

[0040]

[0041] In the above structure, the work function of the metal is preferably 4.0 eV or more and 5.3 eV or less.

[0042] In the above structure, the LUMO (Lowest Unoccupied Molecular Orbital) energy level of the first organic compound is preferably -3.6 eV or more and -2.3 eV or less.

[0043] In the above structure, the metal is preferably a transition metal, more preferably a metal belonging to any one of Group 5, Group 7, Group 9, and Group 11, further preferably a transition metal belonging to Group 11, and even more preferably Ag or Cu.

[0044] In the above structure, the heteroaromatic ring preferably includes a substituted or unsubstituted electron-deficient heteroaromatic ring, more preferably includes any one of a pyridine ring, a diazine ring, and a triazine ring.

[0045] In the above structure, it is preferable that there is also a second layer between the cathode and the first layer, and the second layer contains a second organic compound including an electron-deficient heteroaromatic ring.

[0046] In the above structure, the LUMO energy level of the second organic compound is preferably lower than the energy level of SOMO.

[0047] In the above structure, the first layer preferably does not contain alkali metals and alkaline earth metals.

[0048] In the above structure, the molar ratio of the metal in the first layer to the first organic compound is preferably 0.2 or more and 0.8 or less.

[0049] In the above structure, the cathode preferably contains the same metal as the first layer.

[0050] Another aspect of the present invention is an organic compound represented by structural formulas (200) to (203).

[0051] [Chemical Formula 7]

[0052]

[0053] Other aspects of the present invention are an electronic device including: a display device having each of the above structures; and at least one of a housing and a touch sensor. Other aspects of the present invention are a lighting device including: a light-emitting element having each of the above structures; and at least one of a housing and a touch sensor. Additionally, one aspect of the present invention not only includes a light-emitting device having a light-emitting element within its scope, but also includes an electrical device having a light-emitting device. Therefore, the light-emitting device in this specification refers to an image display device or a light source (including a lighting device). Additionally, the following display modules are also aspects of the present invention: a display module in which a connector such as an FPC (Flexible Printed Circuit) or a TCP (Tape Carrier Package) is installed in a light-emitting element; a display module in which a printed circuit board is provided at an end of the TCP; or a display module in which an IC (integrated circuit) is directly mounted on a light-emitting element by a COG (Chip On Glass) method.

[0054] Advantages of the Invention

[0055] According to one aspect of the present invention, a light-emitting element with a low driving voltage can be provided. According to one aspect of the present invention, a light-emitting element with high moisture resistance can be provided. According to one aspect of the present invention, a light-emitting element with high oxidation resistance can be provided. According to one aspect of the present invention, a light-emitting element with reduced power consumption can be provided. According to one aspect of the present invention, a light-emitting element with high reliability can be provided. According to one aspect of the present invention, a novel light-emitting element can be provided. According to one aspect of the present invention, a novel semiconductor device can be provided. According to one aspect of the present invention, an organic compound applicable to a light-emitting element with high moisture resistance can be provided.

[0056] According to one aspect of the present invention, an electronic device and a lighting device with high moisture resistance using the above light-emitting element can be provided. According to one aspect of the present invention, a light-emitting device with reduced power consumption applicable to the above light-emitting element can be provided. According to one aspect of the present invention, a light-emitting device with a long service life using the above light-emitting element can be provided.

[0057] Note that the description of these effects does not preclude the existence of other effects. One embodiment of the present invention does not necessarily have all of the above effects. In addition, effects other than the above can be known and extracted from the descriptions in the specification, drawings, claims, etc.

[0058] BRIEF DESCRIPTION OF THE DRAWINGS

[0059] [FIG. 1] Cross-sectional schematic diagram of a light-emitting element according to one embodiment of the present invention and a diagram related to the energy levels of an electron injection layer.

[0060] [FIG. 2] Cross-sectional schematic diagram of a light-emitting element according to one embodiment of the present invention.

[0061] [FIG. 3] Cross-sectional schematic diagram of a light-emitting element according to one embodiment of the present invention.

[0062] [FIG. 4] Cross-sectional schematic diagram of a light-emitting element according to one embodiment of the present invention.

[0063] [FIG. 5] Plan view and cross-sectional schematic diagram of a display device according to one embodiment of the present invention.

[0064] [FIG. 6] Cross-sectional schematic diagram of a display device according to one embodiment of the present invention.

[0065] [FIG. 7] Cross-sectional schematic diagram of a display device according to one embodiment of the present invention.

[0066] [FIG. 8] Diagram of an electronic device according to one embodiment of the present invention.

[0067] [FIG. 9] Diagram of an electronic device according to one embodiment of the present invention.

[0068] [FIG. 10] Diagram of an electronic device according to one embodiment of the present invention.

[0069] Figure 11 Diagram of a lighting device according to one embodiment of the present invention.

[0070] Figure 12 Diagram showing the current efficiency - luminance characteristics of the light-emitting element of the example.

[0071] Figure 13 Diagram showing the current - voltage characteristics of the light-emitting element of the example.

[0072] Figure 14 Diagram showing the external quantum efficiency - luminance characteristics of the light-emitting element of the example.

[0073] Figure 15 Diagram showing the field emission spectrum of the light-emitting element of the example.

[0074] Figure 16 ​​​​​​A graph showing the reliability test results of the light-emitting element of the embodiment.

[0075] Figure 17 A graph showing the current efficiency-luminance characteristics of the light-emitting element of the embodiment.

[0076] Figure 18 A graph showing the current-voltage characteristics of the light-emitting element of the embodiment.

[0077] Figure 19 A graph showing the external quantum efficiency-luminance characteristics of the light-emitting element of the embodiment.

[0078] Figure 20 A graph showing the field emission spectrum of the light-emitting element of the embodiment.

[0079] Figure 21 A graph showing the reliability test results of the light-emitting element of the embodiment.

[0080] Figure 22 A graph showing the current efficiency-luminance characteristics of the light-emitting element of the embodiment.

[0081] Figure 23 A graph showing the current-voltage characteristics of the light-emitting element of the embodiment.

[0082] Figure 24 A graph showing the external quantum efficiency-luminance characteristics of the light-emitting element of the embodiment.

[0083] Figure 25 A graph showing the field emission spectrum of the light-emitting element of the embodiment.

[0084] [Figure 26] A graph showing the NMR spectrum of the compound of the embodiment.

[0085] [Figure 27] A graph showing the NMR spectrum of the compound of the embodiment.

[0086] [Figure 28] A graph showing the NMR spectrum of the compound of the embodiment.

[0087] [Figure 29] A graph showing the NMR spectrum of the compound of the embodiment.

[0088] [Figure 30] A graph showing the NMR spectrum of the compound of the embodiment.

[0089] Figure 31 A cross-sectional schematic diagram of the light-emitting element of one aspect of the present invention.

[0090] Figure 32 A graph showing the current efficiency-luminance characteristics of the light-emitting element of the embodiment.

[0091] Figure 33 ​​​​​​​​​​​​A graph showing the current-voltage characteristics of the light-emitting element of the embodiment.

[0092] Figure 34 A graph showing the power efficiency-luminance characteristics of the light-emitting element of the embodiment.

[0093] Figure 35 A graph showing the external quantum efficiency-luminance characteristics of the light-emitting element of the embodiment.

[0094] Figure 36 A graph showing the electric field emission spectrum of the light-emitting element of the embodiment.

[0095] Figure 37 A graph showing the current efficiency-luminance characteristics of the light-emitting element of the embodiment.

[0096] Figure 38 A graph showing the current-voltage characteristics of the light-emitting element of the embodiment.

[0097] Figure 39 A graph showing the power efficiency-luminance characteristics of the light-emitting element of the embodiment.

[0098] Figure 40 A graph showing the external quantum efficiency-luminance characteristics of the light-emitting element of the embodiment.

[0099] Figure 41 A graph showing the electric field emission spectrum of the light-emitting element of the embodiment.

[0100] Figure 42 A graph showing the current efficiency-luminance characteristics of the light-emitting element of the embodiment.

[0101] Figure 43 A graph showing the current-voltage characteristics of the light-emitting element of the embodiment.

[0102] Figure 44 A graph showing the power efficiency-luminance characteristics of the light-emitting element of the embodiment.

[0103] Figure 45 A graph showing the external quantum efficiency-luminance characteristics of the light-emitting element of the embodiment.

[0104] Figure 46 A graph showing the electric field emission spectrum of the light-emitting element of the embodiment.

[0105] Figure 47 A graph showing the current efficiency-luminance characteristics of the light-emitting element of the embodiment.

[0106] Figure 48 A graph showing the current-voltage characteristics of the light-emitting element of the embodiment.

[0107] ​​​​​​​​​​​​​​​​Figure 49 Graph showing the power efficiency - luminance characteristics of the light - emitting element of the embodiment.

[0108] Figure 50 Graph showing the external quantum efficiency - luminance characteristics of the light - emitting element of the embodiment.

[0109] Figure 51 Graph showing the field emission spectrum of the light - emitting element of the embodiment.

[0110] Figure 52 Graph showing the reliability test results of the light - emitting element of the embodiment.

[0111] Mode of implementing the invention

[0112] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the following description, and its mode and details can be changed into various forms without departing from the gist and scope of the present invention. Therefore, the present invention should not be construed as being limited only to the content described in the following embodiments.

[0113] In addition, for ease of understanding, the positions, sizes, ranges, etc. of each structure shown in the drawings and the like do not represent their actual positions, sizes, ranges, etc. Therefore, the disclosed invention is not necessarily limited to the positions, sizes, ranges, etc. disclosed in the drawings and the like.

[0114] In addition, in this specification and the like, for convenience, ordinal numbers such as first and second are added, and they sometimes do not represent the process order or the lamination order. Therefore, for example, "first" can be appropriately replaced with "second" or "third" etc. for explanation. In addition, the ordinal numbers described in this specification and the like are sometimes inconsistent with the ordinal numbers used to specify one mode of the present invention.

[0115] Note that in this specification and the like, when explaining the structure of the invention using the drawings, the same symbols are used for the same parts in different drawings.

[0116] In addition, in this specification and the like, "film" and "layer" can be interchanged with each other. For example, sometimes "conductive layer" can be changed to "conductive film". In addition, for example, sometimes "insulating film" can be changed to "insulating layer".

[0117] (Embodiment 1)

[0118] In this embodiment, one mode of the light - emitting element of the present invention will be described with reference to FIG. 1.

[0119] <Example of the structure of the light - emitting element 1>

[0120] Figure 1A ​​​This is a cross-sectional schematic view of the light-emitting element 150 according to one aspect of the present invention.

[0121] The light-emitting element 150 includes a pair of electrodes (electrode 101 and electrode 102) and an EL layer 100 between the pair of electrodes. The EL layer 100 includes at least a light-emitting layer 140 and an electron injection layer 130.

[0122] In addition, Figure 1A The shown EL layer 100 includes functional layers such as a hole injection layer 111, a hole transport layer 112, and an electron transport layer 118 in addition to the light-emitting layer 140 and the electron injection layer 130.

[0123] Note that although in the present embodiment, electrode 101 of the pair of electrodes is used as the anode and electrode 102 is used as the cathode for description, the structure of the light-emitting element 150 is not limited thereto. That is, electrode 101 can also be used as the cathode and electrode 102 can be used as the anode, and the layers between the electrodes can be stacked in reverse order. In other words, the hole injection layer 111, the hole transport layer 112, the light-emitting layer 140, the electron transport layer 118, and the electron injection layer 130 can be stacked in sequence from the anode side.

[0124] The structure of the EL layer 100 is not limited to Figure 1A the shown structure. It includes at least a light-emitting layer 140 and an electron injection layer 130, and may or may not include the hole injection layer 111, the hole transport layer 112, and the electron transport layer 118.

[0125] In the EL layer between the pair of electrodes, layers can be formed according to the required functions, not limited to the above layers. That is, the EL layer between the pair of electrodes can also include layers having the following functions: reducing the injection barrier of holes or electrons; improving the transportability of holes or electrons; hindering the transportability of holes or electrons; or suppressing the quenching phenomenon caused by the electrodes.

[0126] The light-emitting layer 140 preferably includes a host material and a guest material (light-emitting material).

[0127] As the host material, it is preferable to use one or both of a material having a function of transporting holes (hole transportability) (hole transport material) and a material having a function of transporting electrons (electron transportability) (electron transport material), or a material having both hole transportability and electron transportability can also be used.

[0128] When the host material is a combination of an electron-transporting material and a hole-transporting material (mixed host), the carrier balance can be easily controlled by adjusting the mixing ratio. Specifically, the weight ratio of the electron-transporting material to the hole-transporting material is preferably from 1:9 to 9:1. In addition, by adopting this structure, the carrier balance can be easily controlled, and thus the carrier recombination region can also be easily controlled.

[0129] As the guest material, a light-emitting compound can be used. As the light-emitting compound, a substance capable of emitting fluorescence (hereinafter also referred to as a fluorescent compound) or a substance capable of emitting phosphorescence (hereinafter also referred to as a phosphorescent compound) is preferably used.

[0130] In order to reduce the driving voltage of the light-emitting element, it is necessary to reduce the electron injection barrier between the light-emitting layer 140 and the electrode 102. Therefore, it is preferable to provide an electron injection layer 130 between the light-emitting layer 140 and the electrode 102. In the existing light-emitting elements, the electron injection layer 130 uses a metal material having an alkali metal or an alkaline earth metal with a small work function. However, since the metal material with a small work function has a high reactivity with oxygen and water, when it reacts with oxygen or water in the light-emitting element and the electron injection property decreases, it becomes a cause of a decrease in light-emitting efficiency, an increase in driving voltage, a decrease in element life, the occurrence of shrinkage (non-light-emitting region at the end of the light-emitting portion), etc., and sometimes leads to a decrease in the characteristics or reliability of the light-emitting element. In other words, the metal material with a small work function becomes a cause of element deterioration. Therefore, in order to suppress the decrease in the characteristics or reliability of the light-emitting element, the light-emitting element preferably does not have an alkali metal and an alkaline earth metal.

[0131] On the other hand, although a metal with a large work function has a low reactivity with oxygen and water, when a metal with a large work function is used for the electron injection layer 130, since the electron injection barrier between the light-emitting layer 140 and the electrode 102 becomes large, there are problems such as an increase in the driving voltage of the light-emitting element and a decrease in light-emitting efficiency.

[0132] Here, the present inventors have found that by causing an organic compound having a function of interacting with a metal at 3 or 4 teeth to interact with a transition metal to form a SOMO and using a composite material of the organic compound and the metal forming the SOMO for the electron injection layer, the electron injection barrier from the cathode to the light-emitting layer can be reduced, and a light-emitting element with high moisture resistance can be obtained. That is, the present inventors have found that the electron injection layer 130 can be manufactured even without using an alkali metal and an alkaline earth metal.

[0133] Therefore, a light-emitting element according to one aspect of the present invention is a light-emitting element in which a composite material of an organic compound having a function of interacting with a metal at 3 or 4 teeth and a metal is used for the electron injection layer.

[0134] A SOMO is formed by the interaction between the organic compound and the metal. The SOMO is an orbital derived from the unpaired electrons of the metal and is also distributed on the orbitals of the organic compound. Thus, it can be seen that the electron orbitals of the metal interact with those of the organic compound. In addition, in order to efficiently interact the organic compound with the metal, the organic compound preferably contains many atoms for interaction. Since the organic compound containing many atoms for interaction easily interacts with the metal, the SOMO can be easily formed by mixing the organic compound and the metal. Therefore, the organic compound for the light-emitting element of one embodiment of the present invention preferably has a function of interacting with the metal in 3 or 4 teeth. In addition, when the organic compound containing many atoms for interaction and the metal form the SOMO, the SOMO energy level tends to become high, and the electron injection characteristics from the cathode to the light-emitting layer are improved. In addition, the SOMO can also be formed by interacting with a metal having a large work function. Therefore, the organic compound for the light-emitting element of one embodiment of the present invention preferably has a function of interacting with the metal in 3 or 4 teeth.

[0135] As the atoms that interact with the metal, heteroatoms having lone pairs of electrons in the organic compound can be cited. For example, oxygen (O), nitrogen (N), sulfur (S), and phosphorus (P) can be cited, and nitrogen is preferred. Nitrogen has a relatively high electronegativity and easily interacts with the metal. In addition, since the organic compound having a function of interacting with the metal in 3 or 4 teeth in the light-emitting element of one embodiment of the present invention is used for the electron injection layer, it preferably has electron transport properties. Therefore, the organic compound is preferably an organic compound in which conjugation extends throughout the molecule. Here, nitrogen can form a conjugated bond in the organic compound. Thus, by using nitrogen in the molecule, particularly in the heteroaromatic ring, the organic compound can have high carrier transport properties. Therefore, the interacting atom is preferably nitrogen, and more preferably the nitrogen in the organic compound is included in the heteroaromatic ring. By having this structure, the organic compound can have a function of interacting with the metal and high carrier transport properties. In addition, the heteroaromatic ring is more preferably an even-numbered ring such as a 6-membered ring or an 8-membered ring. In this structure, the lone pair of electrons on nitrogen is not related to conjugation, so it easily interacts with the metal.

[0136] In order for the organic compound having a function of interacting with the metal in 3 or 4 teeth to interact with the metal to form the SOMO, the sum of the number of electrons of the organic compound and the metal is preferably odd. Therefore, when the number of electrons of the organic compound is even, the metal is preferably an odd-numbered group in the periodic table. In addition, when the number of electrons of the organic compound is odd, the metal is preferably an even-numbered group in the periodic table.

[0137] As an organic compound having a function of interacting with a metal with 3 or 4 teeth, an organic compound having a function of transporting electrons is preferably used. In addition, an organic compound that can be used as an electron acceptor for the metal is preferably used.

[0138] In addition, since the organic compound used in one embodiment of the present invention interacts with the metal with 3 or 4 teeth, the function of interacting with the metal is very high. Therefore, in addition to the transition metals of Groups 3 to 11, metals of Group 12 or 13 having a closed-shell d orbital can also be used in one embodiment of the present invention. In addition, metals such as gold (Au) or cobalt (Co) having a very large work function can be used.

[0139] Since metals having a large work function such as metals belonging to Groups 3 to 13 have low reactivity with water and oxygen, when they are used in a light-emitting element, there is less concern about element deterioration caused by water and oxygen compared to when a metal having a small work function is used. Specifically, the work function of the metal is preferably 4.0 eV or more and 5.3 eV or less, more preferably 4.2 eV or more and 5.0 eV or less, further preferably 4.5 eV or more and 5.0 eV or less, and still more preferably 4.7 eV or more and 5.0 eV or less. By having this structure, one embodiment of the present invention can provide a light-emitting element excellent in moisture resistance and oxygen resistance.

[0140] Figure 1B A schematic diagram of the electron injection layer 130 in the light-emitting element showing one embodiment of the present invention. The electron injection layer 130 includes a compound 131 and a metal 132. The compound 131 has a function of interacting with the metal 132 with 3 or 4 teeth.

[0141] Figure 1CAn energy diagram of the electron injection layer 130 in a light-emitting element showing one embodiment of the present invention is presented. When the mixed metal 132 and the compound 131 are combined, the compound 131 interacts with the atoms of the metal 132, thereby forming a SOMO. At this time, the HOMO (Highest Occupied Molecular Orbital) energy level formed by the interaction between the compound 131 and the atoms of the metal 132 is preferably the same as the HOMO energy level of the original compound 131. When an organic compound having a function of transporting electrons is used as the compound 131, the HOMO energy level of the compound 131 is low, and it is not easy to inject holes into the compound 131. Therefore, when the HOMO energy level formed by the interaction between the compound 131 and the metal 132 is equal to the HOMO energy level of the original compound 131, the hole injection barrier between the electron injection layer 130 and the electrode 102 becomes larger, and holes are not easily transferred from the electron injection layer 130 to the electrode 102, which can improve the carrier balance in the light-emitting element, so it is preferred. Note that in this specification and the like, HOMO refers to the molecular orbital with the highest energy occupied by electrons.

[0142] Since the SOMO is an orbital with only one electron, when a voltage is applied to the light-emitting element 150, the electron in the SOMO becomes a carrier in the light-emitting element and is transmitted to the electron transport layer 118 and the light-emitting layer 140. In addition, electrons can be easily injected from the electrode 102 into the electron injection layer 130, and electrons can be easily injected from the electron injection layer 130 into the light-emitting layer 140 through the electron transport layer 118. In other words, since the electron injection layer 130 has a material that forms a combination of SOMOs, electrons can be easily injected from the electrode 102 into the light-emitting layer 140. In addition, the SOMO energy level is preferably lower than the LUMO energy level of the compound 131. Therefore, the LUMO energy level of the compound 131 is preferably higher. Specifically, the LUMO energy level of the compound 131 is preferably -3.6 eV or more and -2.3 eV or less. When an organic compound having such a LUMO energy level is mixed with a metal, the SOMO energy level formed by the interaction becomes an energy level suitable for electron injection, thereby reducing the electron injection barrier from the electrode 102 to the light-emitting layer 140.

[0143] The HOMO energy level and LUMO energy level of an organic compound are generally estimated by CV (cyclic voltammetry), photoelectron spectroscopy, optical absorption spectroscopy, inverse photoelectron spectroscopy, etc. When comparing the values between different compounds, it is preferable to use the values estimated by the same measurement.

[0144] Here, the above-mentioned metal preferably belongs to any one of Group 3, Group 5, Group 7, Group 9, Group 11, and Group 13. The metals of these odd-numbered groups have one electron (unpaired electron) in the outermost orbital, and thus are particularly preferred because they can easily form a SOMO with Compound 131.

[0145] <Estimation of the SOMO energy level of the interaction between Metal 132 and Compound 131 by quantum chemical calculation>

[0146] In the light-emitting element of one embodiment of the present invention, Compound 131 and Metal 132 form a SOMO. However, when the SOMO energy level is significantly low, it is not suitable for the electron injection layer. Therefore, the SOMO energy level formed when Compound 131 interacts with a metal atom is estimated by quantum chemical calculation. Table 1 shows the results. As organic compounds having a function of interacting with a metal in 3 teeth or 4 teeth, 4',4''-(1,4-phenylene)bis(2,2':6',2''-terpyridine) (abbreviation: tPy2P), 4',4''-(9,10-anthryl)bis(2,2':6',2''-terpyridine) (abbreviation: tPy2A), 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), 2,4,6-tris(2-pyridyl)-1,3,5-triazine (abbreviation: 2Py3Tzn), and 2,4,6-tris(5-phenylpyrimidin-2-yl)-1,3,5-triazine (abbreviation: PPm3Tzn) are used.

[0147] [Chemical formula 8]

[0148]

[0149] [Table 1]

[0150]

[0151] The LUMO energy levels of the organic compounds in Table 1 are calculated by cyclic voltammetry (CV).

[0152] As the measuring device, an electrochemical analyzer (ALS model 600A or 600C manufactured by BAS Inc.) was used. A solution for CV measurement was prepared as follows: As the solvent, dehydrated dimethylformamide (DMF) (manufactured by Aldrich Corporation, 99.8%, catalog number: 22705-6) was used, and tetra-n-butylammonium perchlorate (n-Bu4NClO4) (manufactured by Tokyo Chemical Industry Co., Ltd., catalog number: T0836), which is a supporting electrolyte, was dissolved at a concentration of 100 mmol / L, and the object to be measured was dissolved at a concentration of 2 mmol / L for preparation. In addition, a platinum electrode (PTE platinum electrode manufactured by BAS Inc.) was used as the working electrode, a platinum electrode (Pt counter electrode for VC-3 (5 cm) manufactured by BAS Inc.) was used as the auxiliary electrode, and an Ag / Ag + electrode (RE7 non-aqueous solvent type reference electrode manufactured by BAS Inc.) was used as the reference electrode. In addition, the measurement was carried out at room temperature (20 °C or higher and 25 °C or lower). The scanning speed during CV measurement was unified to 0.1 V / sec, and the oxidation potential Ea [V] and reduction potential Ec [V] relative to the reference electrode were measured. Ea is the intermediate potential between the oxidation-reduction waves, and Ec is the intermediate potential between the reduction-oxidation waves. Here, since the potential energy of the reference electrode used in this example relative to the vacuum level is -4.94 [eV], the HOMO level [eV] = -4.94 - Ea and the LUMO level [eV] = -4.94 - Ec were used to calculate the HOMO level and the LUMO level respectively.

[0153] As a quantum chemistry calculation program, Gaussian09 was used. Calculations were performed using a high-performance computer (manufactured by SGI Corporation, ICE X). First, the most stable structures in the ground states of organic compounds, metals, and composites of organic compounds and metals were calculated using density functional theory (DFT). 6-311G(d, p) and LanL2DZ were used as basis functions. B3LYP was used as the exchange-correlation functional. Next, the stabilization energy was calculated by subtracting the sum of the total energies of the organic compound and the metal from the total energy of the composite of the organic compound and the metal. In other words, (stabilization energy) = (total energy of the composite of the organic compound and the metal) - (total energy of the organic compound) - (total energy of the metal). All energies of DFT were expressed as the sum of the potential energy, the electrostatic energy between electrons, the kinetic energy of electrons, and the exchange-correlation energy including all complex electron-electron interactions. In DFT, since the exchange-correlation interaction was approximated using a functional of the single-electron potential (meaning a function of a function) expressed in terms of electron density, the calculation accuracy was high.

[0154] Table 1 shows the results of calculating the SOMO energy levels formed by each organic compound and each metal for manganese (Mn), a transition metal of Group 7, cobalt (Co), a transition metal of Group 9, copper (Cu), silver (Ag), and gold (Au), transition metals of Group 11, and aluminum (Al) and indium (In), metals of Group 13. In addition, the SOMO energy levels formed by lithium (Li), which is widely used as an electron injection layer material, and each organic compound were also calculated. The following results were obtained through the calculations: In all combinations of organic compounds and metals shown in Table 1, the organic compound and the metal interacted and were stabilized near the nitrogen in the heteroaromatic ring included in the organic compound, and the stabilization energy was negative. That is, when these organic compounds and metals were mixed, the energy was more stable in the case where the organic compound interacted with the metal than in the case where the organic compound did not interact with the metal. Thus, a stable composite material could be obtained by the interaction between an organic compound having a function of interacting with a metal in 3 or 4 teeth and the metal. In addition, as shown in Table 1, the SOMO energy levels formed by the organic compounds having a function of interacting with a metal in 3 or 4 teeth and each metal were approximately equal to the SOMO energy levels formed by each organic compound and Li. From this, it was understood that the composite material of the organic compound having a function of interacting with a metal in 3 or 4 teeth and the metal had high electron injection properties. In particular, composites using Cu, Ag, Au of Group 11 elements or Co of Group 9 elements showed high SOMO energy levels, and from this, it was understood that the composite material of the organic compound having a function of interacting with a metal in 3 or 4 teeth and a metal belonging to Group 9 or Group 11 had high electron injection characteristics.

[0155] In addition, as can be seen from Table 1, the SOMO energy levels formed by the organic compounds having the function of interacting with 3 or 4 teeth and each metal are more easily affected by the LUMO energy levels of the organic compounds than the work functions of the respective metals. Therefore, by using an organic compound with a high LUMO energy level, a composite material of an organic compound and a metal with high SOMO energy levels and electron injection characteristics can be manufactured. As described above, the LUMO energy level of the organic compound is preferably -3.6 eV or more and -2.3 eV or less.

[0156] On the other hand, when considering the manufacturing process of the light-emitting element, generally, the EL layer of the light-emitting element, particularly the electron injection layer and the cathode, are formed by vacuum evaporation. At this time, it is preferable to use a material that can be easily vacuum-evaporated, that is, a material with a low melting point, boiling point, or sublimation point, and it is also preferable to use a material with a low temperature that becomes the vapor pressure during vacuum evaporation. Here, the melting points of Group 11 elements or Group 13 elements are lower than those of Group 7 or Group 9 elements, so Group 11 elements or Group 13 elements are suitable for vacuum evaporation. In particular, Group 11 elements or Group 13 elements such as Ag or Al have low melting points, so by using the vacuum evaporation method, metal atoms and organic compounds can be simply mixed, so they are preferable.

[0157] Ag, Cu, Au, Al, and In can also be used as cathode materials. By using the same material for the electron injection layer 130 and the electrode 102, the light-emitting element can be simply manufactured, so it is preferable. In addition, by using the same material for the electron injection layer 130 and the electrode 102, the adhesion between the electron injection layer 130 and the electrode 102 can be improved, so the reliability of the light-emitting element can be improved. In addition, the manufacturing cost of the light-emitting element can be reduced.

[0158] In addition, in the light-emitting element according to one embodiment of the present invention, a metal with a large work function can be used for the electron injection layer 130. Therefore, a metal with a work function equal to or greater than the work function of the metal contained in the electrode 102 can be used for the electron injection layer 130. In the light-emitting element according to one embodiment of the present invention, even if a metal with a large work function is used, the electron injection barrier between the electrode 102 and the electron injection layer 130 can be reduced, thereby reducing the driving voltage.

[0159] Preferably, when compound 131 interacts with metal 132, metal 132 is an electron donor and compound 131 is an electron acceptor. In this case, compound 131 preferably has a plurality of electron-deficient heteroaromatic rings. When such a structure is adopted, since compound 131 easily receives electrons, SOMO is easily formed when interacting with atoms of metal 132. In addition, since compounds having electron-deficient heteroaromatic rings have excellent electron transport properties, when used in an electron injection layer, the driving voltage of the light-emitting element can be reduced, and therefore compounds having electron-deficient heteroaromatic rings are preferably used as compound 131.

[0160] The electron-deficient heteroaromatic ring is preferably a nitrogen-containing heteroaromatic ring, preferably having at least one of a pyridine ring, a diazine ring (pyrimidine ring, a pyrazine ring, a pyridazine ring) and a triazine ring. Due to the excellent electrochemical stability of these rings, a light-emitting element with high reliability can be provided. In addition, due to the excellent electron transport properties, a light-emitting element with a reduced driving voltage can be provided. In addition, as a compound having the electron-deficient heteroaromatic ring, a metal complex can also be used.

[0161] When an organic compound is used as compound 131, the number of carbon atoms is preferably greater than 25 and less than 100. By adopting such a number of carbon atoms, an organic compound with good sublimation properties can be realized, thereby suppressing the thermal decomposition of the organic compound during vacuum evaporation, thereby obtaining good utilization efficiency of the material. Furthermore, the glass transition point (Tg) is preferably greater than 100°C. By using an organic compound having such a Tg for the EL layer, a light-emitting element with excellent heat resistance can be realized.

[0162] Note that in the organic compound used for this calculation, N as a coordinating atom is present on a heterocyclic ring and has a conjugated double bond arranged in the order of NCCN across multiple heterocyclic rings. This is because a chelate ring can be formed when compound 131 interacts with transition metal 132 (compound 131 interacts with metal 132 to form a ring structure). The combination of compound 131 and metal 132 that can form a chelate ring is easy to interact with each other to form SOMO, so it is preferred.

[0163] Therefore, the organic compound having a function of interacting with a metal in a tridentate or tetradentate manner that can be suitably used in the light-emitting element of one embodiment of the present invention has a structure represented by the following general formula (G0).

[0164] [Chemical formula 9]

[0165]

[0166] In the general formula (G0), A 1 , A 2 and A 3Each independently represents a substituted or unsubstituted heteroaromatic ring having 1 or more and 30 or less carbon atoms, A 1 、A 2 and A 3 may also form a fused ring with each other.

[0167] The organic compound represented by the general formula (G0) has conjugated double bonds in which N on the heteroaromatic ring is arranged in the order of N-C-C-N, and has a function of interacting with a metal with 3 or more teeth. As described above, an organic compound having such a structure easily forms a SOMO when mixed with a metal, and the organic compound can be suitably used for a light-emitting element according to one embodiment of the present invention.

[0168] In the above general formula (G0), as the A 1 、A 2 and A 3 The substituted or unsubstituted heteroaromatic ring having 1 or more and 30 or less carbon atoms represented may include, for example, a pyridine ring, a diazine ring (pyrimidine ring, pyrazine ring, pyridazine ring), a triazine ring, a quinoline ring, a quinoxaline ring, a quinazoline ring, a benzoquinazoline ring, a phenanthroline ring, an azafluoranthene ring, an imidazole ring, an oxazole ring, and an oxadiazole ring. Specifically, heteroaromatic rings represented by the following (A-1) to (A-16) can be cited. Note that the substituted or unsubstituted heteroaromatic ring having 1 or more and 30 or less carbon atoms represented by A 1 、A 2 and A 3 is not limited to this. 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.

[0169] [Chemical formula 10]

[0170]

[0171] In addition, an organic compound having a function of interacting with a metal with 3 or 4 teeth and suitable for a light-emitting element according to one embodiment of the present invention has a structure represented by the following general formula (G1).

[0172] [Chemical formula 11]

[0173]

[0174] In the general formula (G1), X 1 to X 6Each independently represents carbon (C) or nitrogen (N), where carbon includes hydrogen, an alkyl group having 1 to 4 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 or more and 25 or less carbon atoms, or a substituted or unsubstituted heteroaryl group having 3 or more and 30 or less carbon atoms, R 1 to R 4 Each independently represents hydrogen, an alkyl group having 1 to 4 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 or more and 25 or less carbon atoms, or a substituted or unsubstituted heteroaryl group having 3 or more and 30 or less carbon atoms, and Ar represents hydrogen, an alkyl group having 1 to 4 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, an aryl group having 6 or more and 60 or less carbon atoms, or a heteroaryl group having 2 or more and 60 or less carbon atoms.

[0175] An organic compound having a function of interacting with a metal in 3 or 4 teeth, such as the organic compound represented by the general formula (G1), preferably has at least one of a pyridine ring, a diazine ring (pyrimidine ring, pyrazine ring, pyridazine ring), and a triazine ring. Since the electrochemical stability of these rings is excellent, a light-emitting element with high reliability can be provided. In addition, since the electron transport property is excellent, a light-emitting element with a reduced driving voltage can be provided.

[0176] In addition, an organic compound having a function of interacting with a metal in 3 or 4 teeth, which can be suitably used for a light-emitting element according to one embodiment of the present invention, has a structure represented by the following general formula (G2).

[0177] [Chemical formula 12]

[0178]

[0179] In the general formula (G2), X 1 and X 2 Each independently represents carbon (C) or nitrogen (N), where carbon includes hydrogen, an alkyl group having 1 to 4 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 or more and 25 or less carbon atoms, or a substituted or unsubstituted heteroaryl group having 3 or more and 30 or less carbon atoms, R 1 to R 8Each independently represents hydrogen, an alkyl group having 1 to 4 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 or more and 25 or less carbon atoms, or a substituted or unsubstituted heteroaryl group having 3 or more and 30 or less carbon atoms, and Ar represents hydrogen, an alkyl group having 1 to 4 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, an aryl group having 6 or more and 60 or less carbon atoms, or a heteroaryl group having 3 or more and 60 or less carbon atoms.

[0180] Organic compounds having a pyridine skeleton tend to have a high LUMO energy level. Therefore, when an organic compound having a pyridine skeleton represented by the general formula (G2) is mixed with a metal, a composite material having a high SOMO energy level can be produced. That is, by mixing an organic compound including a pyridine ring and having a function of interacting with a metal in 3 or 4 teeth with a metal, a composite material having high electron injection properties can be produced.

[0181] In addition, an organic compound having a function of interacting with a metal in 3 or 4 teeth and suitable for a light-emitting element according to one embodiment of the present invention is represented by any one of the following general formulas (G3-1) to (G3-3).

[0182] [Chemical formula 13]

[0183]

[0184] In the general formulas (G3-1) to (G3-3), R 1 to R 8 Each independently represents hydrogen, an alkyl group having 1 to 4 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 or more and 25 or less carbon atoms, or a substituted or unsubstituted heteroaryl group having 3 or more and 30 or less carbon atoms, and Ar represents hydrogen, an alkyl group having 1 to 4 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, an aryl group having 6 or more and 60 or less carbon atoms, or a heteroaryl group having 2 or more and 60 or less carbon atoms.

[0185] In addition, an organic compound having a function of interacting with a metal in 3 or 4 teeth and suitable for a light-emitting element according to one embodiment of the present invention is represented by any one of the following general formulas (G4-1) to (G4-3).

[0186] [Chemical formula 14]

[0187]

[0188] In General Formulas (G4-1) to (G4-3), Ar represents hydrogen, an alkyl group having 1 to 4 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, an aryl group having 2 or more and 60 or less carbon atoms, or a heteroaryl group having 2 or more and 60 or less carbon atoms.

[0189] <Examples of substituents>

[0190] In General Formulas (G0) to (G3), as the substituents represented by R 1 to R 8 or the substituents included in C, hydrogen, an alkyl group having 1 to 4 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 or more and 25 or less carbon atoms, or a substituted or unsubstituted heteroaryl group having 3 or more and 30 or less carbon atoms can be cited. Specifically, as the above alkyl group, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, n-hexyl, etc. can be cited. As the above cycloalkyl group, for example, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, etc. can be cited. As the above aryl group, phenyl, naphthyl, biphenyl, fluorene group, spirofluorene group, etc. can be cited. More specifically, for example, groups represented by the following structural formulas (R-1) to (R-56) can be cited. Note that the substituents represented by R 1 to R 8 or the substituents included in C are not limited thereto.

[0191] [Chemical Formula 15]

[0192]

[0193] In addition, in General Formulas (G0) to (G3), Ar represents hydrogen, an alkyl group having 1 to 4 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, an aryl group having 6 or more and 60 or less carbon atoms, or a heteroaryl group having 3 or more and 60 or less carbon atoms. Specifically, as the above alkyl group, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, n-hexyl, etc. can be cited. As the above cycloalkyl group, for example, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, etc. can be cited. As the above aryl group, phenyl, naphthyl, biphenyl, fluorene group, spirofluorene group, etc. can be cited. More specifically, for example, groups represented by the following structural formulas (Ar-1) to (Ar-48) can be cited. Note that the groups represented by Ar are not limited thereto and may also have substituents.

[0194] [Chemical Formula 16]

[0195]

[0196] <Specific examples of compounds>

[0197] As specific structures of the compounds represented by general formulas (G0) to (G3), organic compounds represented by the following structural formulas (100) to (111) and structural formulas (200) to (211) can be cited. Note that the organic compounds represented by general formulas (G0) to (G3) are not limited to the following examples.

[0198] [Chemical formula 17]

[0199]

[0200] [Chemical formula 18]

[0201]

[0202] The molar ratio of metal 132 to compound 131 is preferably 0.1 or more and 10 or less, more preferably 0.2 or more and 2 or less, and still more preferably 0.2 or more and 0.8 or less. By mixing metal 132 and compound 131 in such a ratio, a light-emitting element having excellent electron injection properties can be provided. When the molar ratio of metal 132 to compound 131 is too low compared with the above ratio, the amount of compound 131 that interacts with metal 132 to form SOMO is small, so the electron injection property sometimes deteriorates. In addition, when the molar ratio of metal 132 to compound 131 is too high compared with the above ratio, the transmittance of the electron injection layer 130 decreases, so the luminous efficiency of the light-emitting element sometimes deteriorates.

[0203] The LUMO energy level of the organic compound contained in the electron transport layer 118 is preferably lower than the SOMO energy level formed in the electron injection layer 130. By adopting such a structure, the electron injection barrier between the electron injection layer 130 and the electron transport layer 118 can be reduced, and thus the driving voltage can be reduced. In addition, since the organic compound contained in the electron transport layer 118 is required to have electron transport properties, it preferably includes an electron-deficient heteroaromatic ring.

[0204] The thickness of the electron injection layer 130 is preferably 3 nm or more, more preferably 5 nm or more. By adopting this structure, it is beneficial for the composite material mixed with metal 132 and compound 131 to play a better role. In addition, the thickness of the electron injection layer 130 is preferably 50 nm or less, more preferably 20 nm or less, and still more preferably 10 nm or less. By adopting this structure, the light absorption of the electron injection layer 130 can be reduced, and a light-emitting element with high luminous efficiency can be provided.

[0205] <Structural example 2 of the light-emitting element>

[0206] Next, with reference to Figure 2A Structural examples different from the light-emitting element 150 shown in FIG. 1 will be described.

[0207] Figure 2A It is a cross-sectional schematic diagram of a light-emitting device showing one embodiment of the present invention. In addition, in Figure 2A sometimes, parts having the same functions as the reference numerals shown in FIG. 1 are denoted by the same shading and their reference numerals are omitted. In addition, sometimes the same reference numerals are used to denote parts having the same functions and their detailed descriptions are omitted.

[0208] The light-emitting element 152 includes a pair of electrodes (electrode 101 and electrode 102) and an EL layer 100 between the pair of electrodes. The EL layer 100 includes at least a light-emitting layer 140 and an electron injection layer 130. The EL layer 100 further includes a buffer layer 127. The buffer layer 127 is provided between the electron injection layer 130 and the electrode 102.

[0209] Figure 2A The EL layer 100 shown includes functional layers such as a hole injection layer 111, a hole transport layer 112, and an electron transport layer 118 in addition to the light-emitting layer 140.

[0210] In one embodiment of the present invention, the electron injection layer 130 uses a composite material of the above compound 131 and metal 132, and the buffer layer 127 uses a compound 133 having an electron-deficient heteroaromatic ring. Since the electron transport property of the electron-deficient heteroaromatic ring is excellent, the driving voltage of the light-emitting element can be reduced.

[0211] By sandwiching the buffer layer 127 between the electron injection layer 130 and the electrode 102, the electron injection barrier between the electrode 102 and the electron injection layer 130 can be reduced, which is preferable. The thickness of the buffer layer 127 is preferably 1 nm or more and 20 nm or less. By adopting such a structure, the electron injection barrier can be reduced while maintaining high electron transport property.

[0212] The LUMO energy level of the compound 133 is preferably lower than the SOMO energy level formed in the electron injection layer 130. By adopting such a structure, the electron injection barrier between the electron injection layer 130 and the electrode 102 can be reduced, which is preferable.

[0213] <Structural Example 3 of Light-Emitting Element>

[0214] Next, with reference to Figure 2B to Figure 1A the light-emitting element 150 shown and Figure 2A structural examples different from the light-emitting element 152 shown will be described.

[0215] Figure 2B It is a cross-sectional schematic diagram of a light-emitting element showing one embodiment of the present invention. In addition, in Figure 2BIn the figure, sometimes parts having the same functions as those denoted by the reference numerals shown in FIG. 1 are denoted by the same shading, and their reference numerals are omitted. In addition, sometimes the same reference numerals are used to denote parts having the same functions, and their detailed descriptions are omitted.

[0216] The light-emitting element 154 includes a pair of electrodes (electrode 101 and electrode 102) and an EL layer 100 between the pair of electrodes. The EL layer 100 includes at least a light-emitting layer 140 and an electron-injecting layer 130. The EL layer 100 further includes a charge-generation layer 129. The charge-generation layer 129 is provided between the electron-injecting layer 130 and the electrode 102.

[0217] Figure 2B The EL layer 100 shown includes functional layers such as a hole-injecting layer 111, a hole-transporting layer 112, and an electron-transporting layer 118 in addition to the light-emitting layer 140.

[0218] As Figure 2B shown, by providing the charge-generation layer 129 between the electrode 102 and the electron-injecting layer 130, the probability of the electron-injecting layer 130 coming into contact with oxygen or moisture can be reduced, and thus the moisture resistance and oxidation resistance of the light-emitting element can be further improved.

[0219] The charge-generation layer 129 may have a structure in which an electron-accepting material is added to a hole-transporting material, or a structure in which an electron-donating material is added to an electron-transporting material. In addition, these two structures may be laminated, but the structure in which an electron-accepting material is added to a hole-transporting material has high moisture resistance and a small number of laminated layers, and thus is preferable.

[0220] As described above, in the case where the charge-generation layer 129 has a hole-transporting material and an electron-accepting material, when a metal material having an alkali metal or a rare earth metal with a small work function is used as the electron-injecting layer 130, since the electron-accepting material of the charge-generation layer 129 extracts electrons from the material for the electron-injecting layer 130, a depletion layer is formed near the interface between the charge-generation layer 129 and the electron-injecting layer 130. Therefore, the driving voltage sometimes increases. In order to prevent the formation of this depletion layer, a layer having a function of transporting electrons needs to be provided between the electron-injecting layer 130 and the charge-generation layer 129.

[0221] On the other hand, in a light-emitting element according to one embodiment of the present invention, by including a composite material of a transition metal and an organic compound having a function of interacting with a metal in 3 or 4 teeth in the electron-injecting layer 130, the charge-generation layer 129 can be provided without forming the above-described depletion layer, and thus a light-emitting element having a small number of laminated layers and a low driving voltage can be manufactured.

[0222] There is no particular limitation on the thickness of the charge generation layer 129, and the thickness can be appropriately adjusted. For example, by adjusting the thickness from the light-emitting layer 140 to the electrode 102, light emitted from the light-emitting layer 140 can be efficiently extracted to the outside of the light-emitting element. In other words, by adjusting the thickness of the charge generation layer 129, the light extraction efficiency can be improved.

[0223] The charge generation layer 129 and the electrode 102 are preferably arranged in contact with each other. By adopting this structure, the electron injection barrier between the electrode 102 and the EL layer 100 can be reduced, and thus the driving voltage of the light-emitting element can be reduced. Furthermore, more preferably, the charge generation layer 129 is in contact with the electron injection layer 130. In one aspect of the present invention, a light-emitting element with a low driving voltage can be manufactured even when the charge generation layer 129 is in contact with the electron injection layer 130. Therefore, by adopting this structure, the number of stacked layers of the EL layer 100 can be reduced.

[0224] Transition metal oxides are suitable for use as the electron-accepting material contained in the charge generation layer 129. As such transition metal oxides, for example, titanium oxide, vanadium oxide, tantalum oxide, molybdenum oxide, tungsten oxide, rhenium oxide, ruthenium oxide, chromium oxide, zirconium oxide, hafnium oxide, and silver oxide can be cited. Molybdenum oxide is particularly preferably used because it is stable in the atmosphere, has low hygroscopicity, and is inexpensive. By using this transition metal oxide, the electron injection barrier between the electrode 102 and the charge generation layer 129 can be reduced, so it is preferred. Therefore, one aspect of the present invention is a light-emitting element in which the electron injection layer 130 contains a transition metal element and the charge generation layer 129 contains a transition metal element. Note that the electron-accepting material contained in the charge generation layer 129 is not limited to the above compounds.

[0225] As the hole-transporting material contained in the charge generation layer 129, an organic compound containing one of a pyrrole skeleton, a thiophene skeleton, a furan skeleton, and an aromatic amine skeleton is preferably used. Since the organic compound having such a skeleton has high hole-transporting properties, the driving voltage of the light-emitting element can be reduced by using this organic compound for the charge generation layer 129. The hole-transporting material contained in the charge generation layer 129 is not limited to the above compounds.

[0226] The composite material of the above metal 132 and the compound 131 having a function of interacting with the metal in 3 or 4 teeth can be used for thin-film solar cells. More specifically, the above composite material is also applicable to the electron injection layer of thin-film solar cells.

[0227] <Constituent elements of the light-emitting element>

[0228] Next, the details of the constituent elements of the light-emitting element shown in FIGS. 1 and 2 will be described.

[0229] "Electron Injection Layer"

[0230] The electron injection layer 130 is a layer containing a substance with high electron injection properties. A composite material of the above metal and an organic compound having a function of interacting with the metal at 3 or 4 teeth is suitable for these layers. As the organic compound having a function of interacting with the metal at 3 or 4 teeth, an organic compound represented by general formulas (G0) to (G4-3) can be used. Specifically, organic compounds represented by structural formulas (100) to (111) and structural formulas (200) to (211) can be used. A heterocyclic compound having a diazine (pyrimidine or pyrazine) skeleton and a triazine skeleton has high electron transport properties and also helps to reduce the driving voltage, so it is particularly preferred. In addition, the metal and the organic compound having a function of interacting with the metal at 3 or 4 teeth preferably have an electron mobility of 1×10 -6 cm 2 / Vs or more. In addition, as long as the substance has higher electron transport properties than hole transport properties, substances other than the above substances can be used for the electron injection layer 130.

[0231] "Hole Injection Layer"

[0232] The hole injection layer 111 and the charge generation layer 129 have the function of reducing the injection barrier of holes from one of a pair of electrodes (electrode 101 or electrode 102) and promoting hole injection. For example, transition metal oxides, phthalocyanine derivatives, or aromatic amines can be used to form them. Examples of the transition metal oxides include molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, manganese oxide, etc. Examples of the phthalocyanine derivatives include phthalocyanine or metal phthalocyanine, etc. Examples of the aromatic amines include benzidine derivatives or phenylenediamine derivatives, etc. In addition, polymer derivatives such as polythiophene or polyaniline can also be used. Typically, poly(ethylenedioxythiophene) / poly(styrenesulfonic acid) etc., which is a self-doped polythiophene.

[0233] The hole injection layer 111 and the charge generation layer 129 may also contain a composite material of a hole transporting material and a material that exhibits electron accepting properties with respect to the hole transporting material. Alternatively, a laminate of a layer containing a material that exhibits electron accepting properties and a layer containing a hole transporting material may be used. In a steady state or in the presence of an electric field, charge transfer can occur between these materials. Examples of the material that exhibits electron accepting properties include organic acceptors such as quinodimethane derivatives, tetrachlorobenzoquinone derivatives, and hexaazatriphenylene derivatives. Specifically, 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloroquinone, 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), etc., which are compounds having an electron-withdrawing group (especially a halogen group such as a fluorine group or a cyano group). In particular, compounds in which an electron-withdrawing group is bonded to a condensed aromatic ring having a plurality of heteroatoms such as HAT-CN are thermally stable, and thus are preferred. In addition, [3]axylene derivatives including an electron-withdrawing group (especially a halogen group such as a fluorine group or a cyano group) have very high electron accepting properties and are particularly preferred. Specifically, α,α’,α”-1,2,3-cycloalkanetriylidene tris[4-cyano-2,3,5,6-tetrafluorobenzyl cyanide], α,α’,α”-1,2,3-cyclopropanetriyl tris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzyl cyanide], α,α’,α”-1,2,3-cycloalkanetriylidene tris[2,3,4,5,6-pentafluorobenzyl cyanide], etc. can be mentioned. In addition, transition metal oxides, for example, oxides of metals in Groups 4 to 8, can also be used. Specifically, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, rhenium oxide, etc. can be used. Molybdenum oxide is particularly preferably used because it is stable in the atmosphere, has low hygroscopicity, and is easy to handle.

[0234] As the hole transporting material, a material having a higher hole transporting property than an electron transporting property can be used, and a material having a hole mobility of 1×10 -6 cm 2 / Vs or more is preferably used. Specifically, aromatic amines, carbazole derivatives, aromatic hydrocarbons, stilbene derivatives, etc., which are hole transporting materials that can be used for the light emitting layer 140, can be used, and preferably have a heteroaromatic skeleton having 1 to 20 carbon atoms. Particularly preferably, it has a nitrogen-containing five-membered heteroaromatic ring skeleton. The above hole transporting material may also be a polymer compound.

[0235] In addition, aromatic hydrocarbons can also be cited as hole-transporting materials. For example, 2-tert-butyl-9,10-bis(2-naphthyl)anthracene (abbreviation: t-BuDNA), 2-tert-butyl-9,10-bis(1-naphthyl)anthracene, 9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA), 2-tert-butyl-9,10-bis(4-phenylphenyl)anthracene (abbreviation: t-BuDBA), 9,10-bis(2-naphthyl)anthracene (abbreviation: DNA), 9,10-diphenylanthracene (abbreviation: DPAnth), 2-tert-butylanthracene (abbreviation: t-BuAnth), 9,10-bis(4-methyl-1-naphthyl)anthracene (abbreviation: DMNA), 2-tert-butyl-9,10-bis[2-(1-naphthyl)phenyl]anthracene, 9,10-bis[2-(1-naphthyl)phenyl]anthracene, 2,3,6,7-tetramethyl-9,10-bis(1-naphthyl)anthracene, 2,3,6,7-tetramethyl-9,10-bis(2-naphthyl)anthracene, 9,9'-bianthracene, 10,10'-diphenyl-9,9'-bianthracene, 10,10'-bis(2-phenylphenyl)-9,9'-bianthracene, 10,10'-bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9'-bianthracene, anthracene, tetracene, rubrene, chrysene, 2,5,8,11-tetra(tert-butyl)chrysene, etc. can be cited. In addition, pentacene, coronene, etc. can also be used. Thus, it is more preferable to use an aromatic hydrocarbon having a hole mobility of 1×10 -6 cm 2 / Vs or more and having 14 to 42 carbon atoms.

[0236] In addition, the aromatic hydrocarbon can have a vinyl skeleton. As the aromatic hydrocarbon having a vinyl group, for example, 4,4'-bis(2,2-diphenylethynyl)biphenyl (abbreviation: DPVBi), 9,10-bis[4-(2,2-diphenylethynyl)phenyl]anthracene (abbreviation: DPVPA), etc. can be cited.

[0237] In addition, thiophene compounds, furan compounds, fluorene compounds, triphenylene compounds, phenanthrene compounds, etc., such as 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II), 4,4',4''-(benzene-1,3,5-triyl)tris(dibenzofuran) (abbreviation: DBF3P-II), 1,3,5-tris(dibenzothiophen-4-yl)benzene (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), 4-[3-(triphenylene-2-yl)phenyl]dibenzothiophene (abbreviation: mDBTPTp-II), etc. can be used. Among them, compounds having a pyrrole skeleton, a furan skeleton, a thiophene skeleton, and an aromatic amine skeleton are stable and have good reliability, so they are preferred. Compounds having the above skeletons have high hole transport properties and also contribute to a reduction in driving voltage.

[0238] Hole Transport Layer

[0239] The hole transport layer 112 is a layer containing a hole transporting material, and the materials exemplified as the materials for the hole injection layer 111 can be used. The hole transport layer 112 has a function of transporting holes injected from the hole injection layer 111 to the light emitting layer 140.

[0240] In addition, it is preferable to use a hole transporting material having a HOMO energy level between the LUMO energy level of the acceptor material contained in the hole injection layer 111 and the HOMO energy level of the material contained in the light emitting layer 140 for the hole transport layer 112. In addition, the hole transport layer 112 is not limited to a single layer and may also be a laminate of two or more layers. In this case, it is preferable to laminate the hole transporting materials in such a manner that the HOMO energy level decreases successively from the hole injection layer 111 side to the light emitting layer 140 side. When the hole transport layer 112 has a laminate of two or more layers, in order to smoothly transport holes, the difference in the HOMO energy levels of the respective hole transporting materials is preferably 0 eV or more and 0.5 eV or less, more preferably 0 eV or more and 0.3 eV or less, and further preferably 0 eV or more and 0.2 eV or less.

[0241] As materials having hole transporting properties, examples thereof include: 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4'-bis[N-(spiro-9,9'-bifluorene-2-yl)-N-phenylamino]biphenyl (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-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-bis(1-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]fluorene-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]spiro-9,9'-bifluorene-2-amine (abbreviation: PCBASF) and other compounds having an aromatic amine skeleton; 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-bis(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP) and other compounds 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 other compounds 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 other compounds having a furan skeleton. Among them, the compounds having an aromatic amine skeleton and the compounds having a carbazole skeleton have high reliability and high hole transporting properties, and also help to reduce the driving voltage, so they are preferred. In addition to the above hole transporting materials, hole transporting materials can also be selected from various substances for use.

[0242] Furthermore, as substances with high hole-transporting properties, for example, 3-[4-(1-naphthyl)phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 3-[4-(9-phenanthryl)phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPPn), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-bis(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 4-phenyldiphenyl-(9-phenyl-9H-carbazol-3-yl)amine (abbreviation: PCA1BP), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), N-[4-(9H-carbazol-9-yl)phenyl]-N-(4-phenyl)phenylaniline (abbreviation: YGA1BP), 1,3,5-tris(dibenzothiophen-4-yl)benzene (abbreviation: DBT3P-II), 4,4',4''-(benzene-1,3,5-triyl)tris(dibenzofuran) (abbreviation: DBF3P-II), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-[3-(triphenylene-2-yl)phenyl]dibenzothiophene (abbreviation: mDBTPTp-II), 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB or α-NPD), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4',4''-tris(carbazol-9-yl)triphenylamine (abbreviation: TCTA), 4,4',4''-tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA), 4,4',4''-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (abbreviation: MTDATA), 4,4'-bis[N-(spiro-9,9'-bifluorene-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB) and other compounds with an aromatic amine skeleton, 3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2), 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1), etc. In addition, carbazole compounds such as 4,4'-bis(N-carbazolyl)biphenyl (abbreviation: CBP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB), amine compounds, dibenzothiophene compounds, dibenzofuran compounds, fluorene compounds, triphenylene compounds or phenanthrene compounds can be used. The substances described herein mainly have a hole mobility of 1×10 -6 cm2 Substances with a voltage of / Vs or higher. However, as long as the substance has a higher hole transport property than electron transport property, substances other than these can be used.

[0243] In addition, these compounds that can be used for the hole transport layer can also be used for the hole injection layer. Additionally, they can also be suitably used as the hole transport material in the charge generation layer 129.

[0244] 《Light-emitting layer》

[0245] The light-emitting layer 140 contains a light-emitting material having a function of emitting light of at least one of purple, blue, blue-green, green, yellow-green, yellow, orange, and red. In addition, the light-emitting layer 140 contains, in addition to the light-emitting material, an electron transport material and / or a hole transport material used as a host material.

[0246] As the light-emitting material, a luminescent substance that converts singlet excited state energy into light or a luminescent substance that converts triplet excited state energy into light can be used. As the above luminescent substances, the following materials can be cited.

[0247] As the luminescent substance that converts singlet excitation energy into light, for example, a substance that emits fluorescence (fluorescent compound) can be cited. There is no particular limitation on the fluorescent compound, and anthracene derivatives, tetracene derivatives, (chrysene) derivatives, phenanthrene derivatives, pyrene derivatives, perylene derivatives, stilbene derivatives, acridone derivatives, coumarin derivatives, phenoxazine derivatives, phenothiazine derivatives, etc. can be preferably used. For example, the following substances can be used.

[0248] Specifically, as such a material, 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine (abbreviation: PAP2BPy), 5,6-bis[4'-(10-phenyl-9-anthryl)biphenyl-4-yl]-2,2'-bipyridine (abbreviation: PAPP2BPy), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn), N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-N,N'-bis(4-tert-butylphenyl)pyrene-1,6-diamine (abbreviation: 1,6tBu-FLPAPrn), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-3,8-dicyclohexylpyrene-1,6-diamine (abbreviation: ch-1,6FLPAPrn), N,N'-(pyrene-1,6-diyl)bis[(6,N-diphenylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-03), N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenyldistyrene-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-butyl)perylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), N,N''-(2-tert-butylanthracene-9,10-diyl-di-4,1-phenylene)bis[N,N',N'-triphenyl-1,4-benzenediamine] (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-benzenediamine (abbreviation: 2DPAPPA), N,N,N',N',N'',N'',N''',N'''-octaphenyldibenzo[g,p] -2,7,10,15 - tetraamine (abbreviation: DBC1), Coumarin 30, N-(9,10 - diphenyl - 2 - anthryl)-N,9 - diphenyl - 9H - carbazole - 3 - amine (abbreviation: 2PCAPA), N-[9,10 - bis(1,1'-biphenyl - 2 - yl)-2 - anthryl]-N,9 - diphenyl - 9H - carbazole - 3 - amine (abbreviation: 2PCABPhA), N-(9,10 - diphenyl - 2 - anthryl)-N,N',N'-triphenyl - 1,4 - phenylenediamine (abbreviation: 2DPAPA), N-[9,10 - bis(1,1'-biphenyl - 2 - yl)-2 - anthryl]-N,N',N'-triphenyl - 1,4 - phenylenediamine (abbreviation: 2DPABPhA), 9,10 - bis(1,1'-biphenyl - 2 - yl)-N-[4-(9H - carbazol - 9 - yl)phenyl]-N - phenylanthracen - 2 - amine (abbreviation: 2YGABPhA), N,N,9 - triphenylanthracen - 9 - amine (abbreviation: DPhAPhA), Coumarin 6, Coumarin 545T, N,N'-diphenylquinacridone (abbreviation: DPQd), Rubrene, 2,8 - di - tert - butyl - 5,11 - bis(4 - tert - butylphenyl)-6,12 - diphenyltetracene (abbreviation: TBRb), Nile Red, 5,12 - bis(1,1'-biphenyl - 4 - yl)-6,11 - diphenyltetracene (abbreviation: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]vinyl}-6 - methyl - 4H - pyran - 4 - ylidene)propanedinitrile (abbreviation: DCM1), 2-{2 - methyl - 6-[2-(2,3,6,7 - tetrahydro - 1H,5H - benzo[ij]quinolizin - 9 - yl)vinyl]-4H - pyran - 4 - ylidene}propanedinitrile (abbreviation: DCM2), N,N,N',N'-tetrakis(4 - methylphenyl)tetracene - 5,11 - diamine (abbreviation: p - mPhTD), 7,14 - diphenyl - N,N,N',N'-tetrakis(4 - methylphenyl)acenaphtho[1,2 - a]fluoranthene - 3,10 - diamine (abbreviation: p - mPhAFD), 2-{2 - isopropyl - 6-[2-(1,1,7,7 - tetramethyl - 2,3,6,7 - tetrahydro - 1H,5H - benzo[ij]quinolizin - 9 - yl)vinyl]-4H - pyran - 4 - ylidene}propanedinitrile (abbreviation: DCJTI), 2-{2 - tert - butyl - 6-[2-(1,1,7,7 - tetramethyl - 2,3,6,7 - tetrahydro - 1H,5H - benzo[ij]quinolizin - 9 - yl)vinyl]-4H - pyran - 4 - ylidene}propanedinitrile (abbreviation: DCJTB), 2-(2,6 - bis{2-[4-(dimethylamino)phenyl]vinyl}-4H - pyran - 4 - ylidene)propanedinitrile (abbreviation: BisDCM), 2-{2,6 - bis[2-(8 - methoxy - 1,1,7,7 - tetramethyl - 2,3,6,7 - tetrahydro - 1H,{5H-benzo[ij]quinolin-9-yl)vinyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJTM), 5,10,15,20-tetraphenylbisbenzo,

[0249] [5,6]Indeno[1,2,3-cd:1',2',3'-lm]perylene, etc.

[0250] As a luminescent substance that converts triplet excitation energy into luminescence, for example, a substance that emits phosphorescence (phosphorescent compound) can be cited. In addition, as the phosphorescent compound, an iridium, rhodium, or platinum organometallic complex or a metal complex can be cited. In addition, a platinum complex or an organoiridium complex having a porphyrin ligand can be cited, and among them, an organoiridium complex is particularly preferably used. For example, an iridium orthometallic complex. As the orthometalated ligand, a 4H-triazole ligand, a 1H-triazole ligand, an imidazole ligand, a pyridine ligand, a pyrimidine ligand, a pyrazine ligand, or an isoquinoline ligand, etc. can be cited. At this time, the phosphorescent compound has an absorption band of triplet MLCT (Metal to Ligand Charge Transfer: charge transfer from metal to ligand) transition.

[0251] As a substance having a luminescence peak in the blue or green wavelength region, for example, tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN2]phenyl-κC}iridium(III) (abbreviation: Ir(mpptz-dmp)3), tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazole)iridium(III) (abbreviation: Ir(Mptz)3), tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazole]iridium(III) (abbreviation: Ir(iPrptz-3b)3), tris[3-(5-biphenyl)

[0252] -5-Isopropyl-4-phenyl-4H-1,2,4-triazole]iridium(III) (abbreviation: Ir(iPr5btz)3) and other organometallic iridium complexes with a 4H-triazole skeleton; tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazole]iridium(III) (abbreviation: Ir(Mptz1-mp)3), tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazole)iridium(III) (abbreviation: Ir(Prptz1-Me)3) and other organometallic iridium complexes with a 1H-triazole skeleton; fac-tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviation: Ir(iPrpmi)3), tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: Ir(dmpimpt-Me)3) and other organometallic iridium complexes with an imidazole skeleton; and bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2 ']iridium(III) tetrakis(1-pyrazolyl)borate (abbreviation: FIr6), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2 ']iridium(III) picolinate (abbreviation: FIrpic), bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinato-N,C 2 '}iridium(III) picolinate (abbreviation: Ir(CF3ppy)2(pic)), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2 ']iridium(III) acetylacetonate (abbreviation: FIr(acac)) and other organometallic iridium complexes with phenylpyridine derivatives having an electron-withdrawing group as ligands. Among the above metal complexes, organometallic iridium complexes with a nitrogen-containing five-membered heterocyclic skeleton such as a 4H-triazole skeleton, a 1H-triazole skeleton, and an imidazole skeleton are particularly preferred because they have a very high triplet excitation energy and excellent reliability and luminescence efficiency.

[0253] As substances having a luminescence peak in the green or yellow wavelength region, examples thereof include tris(4-methyl-6-phenylpyrimidine)iridium(III) (abbreviation: Ir(mppm)3), tris(4-tert-butyl-6-phenylpyrimidine)iridium(III) (abbreviation: Ir(tBuppm)3), (acetylacetonato)bis(6-methyl-4-phenylpyrimidine)iridium(III) (abbreviation: Ir(mppm)2(acac)), (acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidine)iridium(III) (abbreviation: Ir(tBuppm)2(acac)), (acetylacetonato)bis[4-(2-norbornanyl)-6-phenylpyrimidine]iridium(III) (abbreviation: Ir(nbppm)2(acac)), (acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidine]iridium(III) (abbreviation: Ir(mpmppm)2(acac)), (acetylacetonato)bis{4,6-dimethyl-2-[6-(2,6-dimethylphenyl)-4-pyrimidinyl-κN3]phenyl-κC}iridium(III) (abbreviation: Ir(dmppm-dmp)2(acac)), (acetylacetonato)bis(4,6-diphenylpyrimidine)iridium(III) (abbreviation: Ir(dppm)2(acac)) and other organometallic iridium complexes having a pyrimidine skeleton; (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazine)iridium(III) (abbreviation: Ir(mppr-Me)2(acac)), (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazine)iridium(III) (abbreviation: Ir(mppr-iPr)2(acac)) and other organometallic iridium complexes having a pyrazine skeleton; tris(2-phenylpyridine-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]quinoline)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)) and other organometallic iridium complexes having a pyridine skeleton; bis(2,4-diphenyl-1,3-oxazole-N,C 2 ')iridium(III) acetylacetonate (abbreviation: Ir(dpo)2(acac)), bis{2-[4'-(perfluorophenyl)phenyl]pyridine-N,C 2Iridium(III) acetylacetonate (abbreviation: Ir(p-PF-ph)2(acac)), bis(2-phenylbenzothiazole-N,C 2 ') iridium(III) acetylacetonate (abbreviation: Ir(bt)2(acac)) and other organometallic iridium complexes; rare earth metal complexes such as tris(acetylacetonato)(monophenanthroline) terbium(III) (abbreviation: Tb(acac)3(Phen)). Among the above substances, organometallic iridium complexes having a pyrimidine skeleton are particularly preferred because they also have significantly excellent reliability and luminous efficiency.

[0254] In addition, as substances having a luminescence peak in the yellow or red wavelength region, for example, (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III) (abbreviation: Ir(5mdppm)2(dibm)), bis[4,6-bis(3-methylphenyl)pyrimidinato](di-neopentanoylmethanato)iridium(III) (abbreviation: Ir(5mdppm)2(dpm)), bis[4,6-di(naphthalen-1-yl)pyrimidinato](di-neopentanoylmethanato)iridium(III) (abbreviation: Ir(d1npm)2(dpm)) and other 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)(di-neopentanoylmethanato)iridium(III) (abbreviation: Ir(tppr)2(dpm)), (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: Ir(Fdpq)2(acac)) and other 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’)Organic metal iridium complexes having a pyridine skeleton such as iridium(III) acetylacetonate (abbreviation: Ir(piq)2(acac)); platinum complexes such as platinum(II) 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin (abbreviation: PtOEP); and rare earth metal complexes such as tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III) (abbreviation: Eu(DBM)3(Phen)), tris[1-(2-thiophenecarbonyl)-3,3,3-trifluoroacetone](monophenanthroline)europium(III) (abbreviation: Eu(TTA)3(Phen)). Among the above substances, organic metal iridium complexes having a pyrimidine skeleton are particularly preferred because they also have significantly excellent reliability and luminous efficiency. In addition, organic metal iridium complexes having a pyrazine skeleton can achieve red light with good chromaticity.

[0255] As the material capable of converting triplet excitation energy into luminescence, in addition to phosphorescent compounds, thermally activated delayed fluorescence (TADF) materials can be cited. Therefore, the description of phosphorescent compounds can be regarded as the description of thermally activated delayed fluorescent compounds. A thermally activated delayed fluorescent compound is a material in which the difference between the singlet excitation level and the triplet excitation level is small and has the function of converting energy from triplet excitation energy into singlet excitation energy through reverse intersystem crossing. Therefore, the triplet excited state can be up-converted to the singlet excited state (reverse intersystem crossing) by a small amount of thermal energy and the luminescence (fluorescence) from the singlet excited state can be efficiently presented. In addition, the conditions for efficiently obtaining thermally activated delayed fluorescence are as follows: the energy difference between the singlet excitation level and the triplet excitation level is preferably greater than 0 eV and 0.3 eV or less, more preferably greater than 0 eV and 0.2 eV or less, and further preferably greater than 0 eV and 0.1 eV or less.

[0256] When the thermally activated delayed fluorescent compound is composed of one material, for example, the following materials can be used.

[0257] First, examples include fullerenes or their derivatives, acridine derivatives such as proflavine, and eosin. Additionally, examples include metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd). As such metal-containing porphyrins, for example, protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF2(OEP)), etioporphyrin-tin fluoride complex (SnF2(Etio I)), octaethylporphyrin-platinum chloride complex (PtCl2OEP), etc. can also be cited.

[0258] In addition, as a thermally activated delayed fluorescence compound composed of one material, a heterocyclic compound having an electron-rich heteroaromatic skeleton and an electron-deficient heteroaromatic skeleton can also be used. Specifically, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 2-[4-(10H-phenoxazin-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: PXZ-TRZ), 3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), 10-phenyl-10H,10’H-spiro[acridine-9,9’-anthracene]-10’-one (abbreviation: ACRSA), etc. can be cited. Since the heterocyclic compound has an electron-rich heteroaromatic skeleton and an electron-deficient heteroaromatic skeleton, it has high electron transportability and hole transportability, and is therefore preferred. In particular, in the electron-deficient heteroaromatic skeleton, a diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton) or a triazine skeleton is stable and has good reliability, and is therefore preferred. In addition, in the electron-rich heteroaromatic skeleton, an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, a thiophene skeleton, and a pyrrole skeleton are stable and have good reliability, and it is therefore preferred to have any one or more of these skeletons. As the pyrrole skeleton, an indole skeleton, a carbazole skeleton, and a 9-phenyl-3,3’-bi-9H-carbazole skeleton are particularly preferably used. In addition, in a substance in which an electron-rich heteroaromatic skeleton and an electron-deficient heteroaromatic skeleton are directly bonded, the donor property of the electron-rich heteroaromatic skeleton and the acceptor property of the electron-deficient heteroaromatic skeleton are both strong, and the difference between the singlet excitation energy level and the triplet excitation energy level becomes small, and it is therefore particularly preferred.

[0259] In addition, the material that exhibits thermally activated delayed fluorescence can be either a material that can generate a singlet excited state from a triplet excited state through reverse intersystem crossing alone, or composed of multiple materials that form an exciplex (also called an Exciplex).

[0260] As the host material for the light-emitting layer 140, a hole-transporting material and an electron-transporting material can be used.

[0261] Although there is no particular limitation on the materials of the host materials that can be used in the light-emitting layer, for example, the following can be cited: tris(8-hydroxyquinoline)aluminum(III) (abbreviation: Alq3), tris(4-methyl-8-hydroxyquinoline)aluminum(III) (abbreviation: Almq3), bis(10-hydroxybenzo[h]quinoline)beryllium(II) (abbreviation: BeBq2), bis(2-methyl-8-hydroxyquinoline)(4-phenylphenol)aluminum(III) (abbreviation: BAlq), bis(8-hydroxyquinoline)zinc(II) (abbreviation: Znq), bis[2-(2-benzoxazolyl)phenol]zinc(II) (abbreviation: ZnPBO), bis[2-(2-benzothiazolyl)phenol]zinc(II) (abbreviation: ZnBTZ) and other metal complexes; 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), bathocuproine (abbreviation: BCP), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11) and other heterocyclic compounds; 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB or α-NPD), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4'-bis[N-(spiro-9,9'-bifluorene-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB) and other aromatic amine compounds. In addition, anthracene derivatives, phenanthrene derivatives, naphthacene derivatives, derivatives, dibenzo[g,p] derivatives and other condensed polycyclic aromatic compounds. Specifically, 9,10-diphenylanthracene (abbreviation: DPAnth), N,N-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: CzA1PA), 4-(10-phenyl-9-anthryl)triphenylamine (abbreviation: DPhPA), YGAPA, PCAPA, N,9-diphenyl-N-{4-[4-(10-phenyl-9-anthryl)phenyl]phenyl}-9H-carbazol-3-amine (abbreviation: PCAPBA), 2PCAPA, 6,12-dimethoxy-5,11-diphenyl DBC1, 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA), 3,6-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: DPCzPA), 9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA), 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 9,9'-bianthracene (abbreviation: BANT), 9,9'-(stilbene-3,3'-diyl)diphenanthrene (abbreviation: DPNS), 9,9'-(stilbene-4,4'-diyl)diphenanthrene (abbreviation: DPNS2), and 1,3,5-tris(1-pyrenyl)benzene (abbreviation: TPB3), etc. One or more substances having an energy gap larger than that of the above-mentioned luminescent materials can be selected from these substances and various substances. In addition, when the luminescent material is a phosphorescent compound, a substance having a triplet excitation energy larger than that of the luminescent material can be selected as the host material.

[0262] When using multiple materials as the host material of the light-emitting layer, it is preferable to use a combination of two compounds that form an exciplex. In this case, various carrier transport materials can be appropriately used. Particularly preferably, in order to efficiently form an exciplex, an electron transport material and a hole transport material are combined.

[0263] This is because: when an electron transport material and a hole transport material are combined to obtain a host material that forms an exciplex, by adjusting the mixing ratio of the electron transport material and the hole transport material, it is easy to optimize the carrier balance between holes and electrons in the light-emitting layer. By optimizing the carrier balance between holes and electrons in the light-emitting layer, it is possible to suppress the region where electrons and holes recombine in the light-emitting layer from being biased to one side. By suppressing the region where recombination occurs from being biased to one side, the reliability of the light-emitting element can be improved.

[0264] As the electron-transporting material, a π-deficient heteroaromatic compound such as a metal complex containing zinc or aluminum, a nitrogen-containing heteroaromatic compound, etc. can be used. Specifically, metal complexes such as bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq2), bis(2-methyl-8-hydroxyquinolinato)(4-phenylphenolato)aluminum(III) (abbreviation: BAlq), bis(8-hydroxyquinolinato)zinc(II) (abbreviation: Znq), bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO) or bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ), 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-Oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II) and other heterocyclic compounds with azole skeletons, 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDBTPDBq-II) and 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 4,6-bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothiophenyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), 4-{3-[3'-(9H-carbazol-9-yl)]biphenyl-3-yl}benzofuro[3,2-d]pyrimidine (abbreviation: 4mCzBPBfpm) and other heterocyclic compounds with diazine skeletons, 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviation: TmPPPyTz), 2,4,6-tris(2-pyridyl)-1,3,5-triazine (abbreviation: 2Py3Tz) and other heterocyclic compounds with triazine skeletons, 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy), 1,3,5-tris[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB) and other heterocyclic compounds with pyridine skeletons. Among them, the heterocyclic compounds with diazine skeletons and triazine skeletons and the heterocyclic compounds with pyridine skeletons have high reliability, so they are preferred. In particular, the heterocyclic compounds with diazine (pyrimidine or pyrazine) skeletons and triazine skeletons have high electron transport properties and also help to reduce the driving voltage.,

[0265] As the hole transporting material, it is preferable to use π - electron - rich heteroaromatics (such as carbazole derivatives or indole derivatives) or aromatic amines, etc. Specifically, examples include: 2 - [N - (9 - phenylcarbazol - 3 - yl) - N - phenylamino]spiro - 9,9'-bifluorene (abbreviation: PCASF), 4,4',4'' - tris[N - (1 - naphthyl) - N - phenylamino]triphenylamine (abbreviation: 1'-TNATA), 2,7 - bis[N - (4 - diphenylaminophenyl) - N - phenylamino]spiro - 9,9'-bifluorene (abbreviation: DPA2SF), N,N'-bis(9 - phenylcarbazol - 3 - yl) - N,N'-diphenylbenzene - 1,3 - diamine (abbreviation: PCA2B), N - (9,9 - dimethyl - 2 - diphenylamino - 9H - fluoren - 7 - yl)diphenylamine (abbreviation: DPNF), N,N',N'' - triphenyl - N,N',N'' - tris(9 - phenylcarbazol - 3 - yl)benzene - 1,3,5 - triamine (abbreviation: PCA3B), 2 - [N - (9 - phenylcarbazol - 3 - yl) - N - phenylamino]spiro - 9,9'-bifluorene (abbreviation: PCASF), 2 - [N - (4 - diphenylaminophenyl) - N - phenylamino]spiro - 9,9'-bifluorene (abbreviation: DPASF), N,N'-bis[4 - (carbazol - 9 - yl)phenyl] - N,N'-diphenyl - 9,9 - dimethylfluorene - 2,7 - diamine (abbreviation: YGA2F), 4,4'-bis[N - (1 - naphthyl) - N - phenylamino]biphenyl (abbreviation: NPB), N,N'-bis(3 - methylphenyl) - N,N'-diphenyl - [1,1'-biphenyl] - 4,4'-diamine (abbreviation: TPD), 4,4'-bis[N - (4 - diphenylaminophenyl) - N - phenylamino]biphenyl (abbreviation: DPAB), 4,4'-bis[N - (spiro - 9,9'-bifluorene - 2 - yl) - N - phenylamino]biphenyl (abbreviation: BSPB), 4 - phenyl - 4'-(9 - phenylfluoren - 9 - yl)triphenylamine (abbreviation: BPAFLP), 4 - phenyl - 3'-(9 - phenylfluoren - 9 - yl)triphenylamine (abbreviation: mBPAFLP), N - (9,9 - dimethyl - 9H - fluoren - 2 - yl) - N - {9,9 - dimethyl - 2 - [N'-phenyl - N'-(9,9 - dimethyl - 9H - fluoren - 2 - yl)amino] - 9H - fluoren - 7 - yl}phenylamine (abbreviation: DFLADFL), 3 - [N - (9 - phenylcarbazol - 3 - yl) - N - phenylamino] - 9 - phenylcarbazole (abbreviation: PCzPCA1), 3 - [N - (4 - diphenylaminophenyl) - N - phenylamino] - 9 - phenylcarbazole (abbreviation: PCzDPA1), 3,6 - bis[N - (4 - diphenylaminophenyl) - N - phenylamino] - 9 - phenylcarbazole (abbreviation: PCzDPA2), N - N’ - bis{4 - [bis(3 - methylphenyl)amino]phenyl} - N,N’ - diphenyl - (1,1’ - biphenyl) - 4,4'-diamine (abbreviation: DNTPD), 3,6-bis[N-(4-diphenylaminophenyl)-N-(1-naphthyl)amino]-9-phenylcarbazole (abbreviation: PCzTPN2), 3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2), 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'-bis(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluorene-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-spiro-9,9'-bifluorene-2-amine (abbreviation: PCBASF), N-(4-biphenyl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9-phenyl-9H-carbazol-3-amine (abbreviation: PCBiF), N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF) and other compounds with an aromatic amine backbone; 1,Compounds having a carbazole skeleton such as 3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-bis(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 9-phenyl-9H-3-(9-phenyl-9H-carbazol-3-yl)carbazole (abbreviation: PCCP); Compounds having a thiophene skeleton such as 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 compounds having a furan skeleton such as 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). Among them, compounds having an aromatic amine skeleton and compounds having a carbazole skeleton have high reliability and high hole transportability, and also help to reduce the driving voltage, so they are preferred.,

[0266] The combination of host materials that form exciplexes is not limited to the above compounds, and compounds in a combination where carriers can move and exciplexes can be formed can be used, where the emission of the exciplex can overlap with the absorption band on the longest wavelength side of the absorption spectrum of the luminescent material (corresponding to the absorption for the transition from the singlet ground state to the singlet excited state of the luminescent material), and other materials can also be used.

[0267] As the host material for the light-emitting layer, a thermally activated delayed fluorescence material can also be used.

[0268] As the electron transport material for the light-emitting layer, the same material as the electron transport material for the electron injection layer can be used. Thereby, the manufacturing of the light-emitting element can be simplified, and thus the manufacturing cost of the light-emitting element can be reduced.

[0269] "Electron Transport Layer and Buffer Layer"

[0270] The electron transport layer 118 and the buffer layer 127 are layers containing substances with high electron transportability. Examples of organic compounds that can be used for the electron transport layer 118 and the buffer layer 127 include metal complexes having quinoline ligands, benzoquinoline ligands, oxazole ligands, thiazole ligands, oxadiazole derivatives, triazole derivatives, phenanthroline derivatives, pyridine derivatives, bipyridine derivatives, etc. In addition, organic compounds having a function of interacting with a metal in a tridentate or tetradentate manner, which are compounds that can be used for the electron injection layer 130, can also be used.

[0271] As the above-mentioned metal complexes with quinoline ligands, benzoquinoline ligands, oxazole ligands, thiazole ligands, oxadiazole derivatives, triazole derivatives, phenanthroline derivatives, pyridine derivatives, bipyridine derivatives, specifically, Alq3, Almq3, BeBq2, BAlq, bis(8-hydroxyquinoline)zinc(II) (abbreviation: Znq), bis[2-(2-benzoxazolyl)phenol]zinc(II) (abbreviation: ZnPBO), bis[2-(2-benzothiazolyl)phenol]zinc(II) (abbreviation: ZnBTZ) and other metal complexes can be used. In addition, 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 3-(4'-tert-butylphenyl)-4-phenyl-5-(4''-biphenylyl)-1,2,4-triazole (abbreviation: TAZ), 3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1,2,4-triazole (abbreviation: p-EtTAZ), 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOS), 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II) and other heterocyclic compounds with an oxazole skeleton, 2-[3-(dibenzothiophen-4-yl)phenyl]dibenz[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenz[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenz[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]dibenz[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenz[f,h]quinoxaline (abbreviation: 7mDBTPDBq-II) and 6-[3-(dibenzothiophen-4-yl)phenyl]dibenz[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 4,6-bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothiophenyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), 4-{3-[3’-(9H-carbazol-9-yl)]biphenyl-3-yl}benzofuro[3,2-d]pyrimidine (abbreviation: 4mCzBPBfpm), and other heterocyclic compounds with a diazine skeleton, 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviation: TmPPPyTz), 2,4,6-tris(2-pyridine)-1,3,5-triazine (abbreviation: 2Py3Tz), and other heterocyclic compounds with a triazine skeleton, 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy), 1,3,5-tris[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), bathocuproine (abbreviation: BCP), 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBPhen), and other heterocyclic compounds with a pyridine skeleton. Among them, heterocyclic compounds with a diazine skeleton and a triazine skeleton and heterocyclic compounds with a pyridine skeleton have high reliability, so they are preferred. In particular, heterocyclic compounds with a diazine (pyrimidine or pyrazine) skeleton and a triazine skeleton have high electron transport properties and also help to reduce the driving voltage. The substances described herein mainly have an electron mobility of 1×10, -6 cm 2 / Vs or more. In addition, as long as the substance has higher electron transport properties than hole transport properties, substances other than the above substances can be used for the electron injection layer 130.

[0272] The electron transport layer 118 and the buffer layer 127 are not limited to a single layer, and two or more layers composed of the above substances can also be stacked.

[0273] In addition, a layer for controlling the movement of electron carriers can be provided between the electron transport layer 118 and the light-emitting layer 140. The layer for controlling the movement of electron carriers is a layer formed by adding a small amount of a substance with high electron capture properties to the above material with high electron transport properties. By suppressing the movement of electron carriers, the carrier balance can be adjusted. This structure has a great effect on suppressing problems caused by electrons passing through the light-emitting layer (such as a decrease in the element life).

[0274] As the electron transport material for the electron transport layer, the same material as the electron transport material for the electron injection layer can be used. In addition, as the electron transport material for the electron transport layer, the same material as the electron transport material for the light-emitting layer can be used. Thereby, the manufacturing of the light-emitting element can be simplified, and the manufacturing cost of the light-emitting element can be reduced.

[0275] In addition, the above-mentioned hole injection layer, hole transport layer, light-emitting layer, electron transport layer, and electron injection layer can be formed by evaporation (including vacuum evaporation), inkjet printing, coating, gravure printing, etc., respectively. In addition, as the above-mentioned hole injection layer, hole transport layer, light-emitting layer, electron transport layer, and electron injection layer, in addition to the above-mentioned materials, inorganic compounds such as quantum dots or polymer compounds (oligomers, dendrimers, polymers, etc.) can also be used.

[0276] As the quantum dots, colloidal quantum dots, alloy-type quantum dots, core-shell type quantum dots, core-type quantum dots, etc. can be used. In addition, quantum dots containing element groups of Group 2 and Group 16, Group 13 and Group 15, Group 13 and Group 17, Group 11 and Group 17, or Group 14 and Group 15 can also be used. Alternatively, quantum dots containing elements such as cadmium (Cd), selenium (Se), zinc (Zn), sulfur (S), phosphorus (P), indium (In), tellurium (Te), lead (Pb), gallium (Ga), arsenic (As), aluminum (Al), etc. can be used.

[0277] As the liquid medium for the wet method, for example, the following can be used: ketones such as methyl ethyl ketone and cyclohexanone; fatty acid esters such as ethyl acetate; halogenated hydrocarbons such as dichlorobenzene; aromatic hydrocarbons such as toluene, xylene, mesitylene, and cyclohexylbenzene; aliphatic hydrocarbons such as cyclohexane, decalin, and dodecane; organic solvents such as N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO).

[0278] Examples of the polymer compound that can be used for the light-emitting layer include: poly(phenylene vinylene) (PPV) derivatives such as poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene] (abbreviation: MEH-PPV), poly(2,5-dioctyl-1,4-phenylene vinylene), etc.; polyfluorene derivatives such as poly(9,9-dinonylfluorene-2,7-diyl) (abbreviation: PF8), poly[(9,9-dinonylfluorene-2,7-diyl)-alt-(benzo[2,1,3]thiadiazole-4,8-diyl)] (abbreviation: F8BT), poly[(9,9-dinonylfluorene-2,7-diyl)-alt-(2,2'-bithiophene-5,5'-diyl)] (abbreviation: F8T2), poly[(9,9-dioctyl-2,7-divinylenefluorenylene)-alt-(9,10-anthracene)], poly[(9,9-dihexylfluorene-2,7-diyl)-alt-(2,5-dimethyl-1,4-phenylene)], etc.; polyalkylthiophene (PAT) derivatives such as poly(3-hexylthiophene) (abbreviation: P3HT), etc., and polyphenylene derivatives. In addition, a light-emitting low-molecular compound can be doped into the above polymer compounds, poly(N-vinylcarbazole) (abbreviation: PVK), poly(2-vinylnaphthalene), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (abbreviation: PTAA), etc., and used for the light-emitting layer. As the light-emitting low-molecular compound, the fluorescent compounds exemplified above can be used.

[0279] 《A Pair of Electrodes》

[0280] Electrodes 101 and 102 are used as the anode or cathode of the light-emitting element. Electrodes 101 and 102 can be formed using metals, alloys, conductive compounds, their mixtures or laminates, etc.

[0281] One of the electrode 101 and the electrode 102 is preferably formed of a conductive material having a function of reflecting light. As such a conductive material, aluminum (Al) or an alloy containing Al can be cited. As an alloy containing Al, an alloy containing Al and L (L represents one or more of titanium (Ti), neodymium (Nd), nickel (Ni), and lanthanum (La)) can be cited. For example, an alloy containing Al and Ti or an alloy containing Al, Ni, and La. Aluminum has a low resistivity and a high light reflectivity. In addition, since aluminum is abundantly contained in the earth's crust and is not expensive, the manufacturing cost of the light-emitting element can be reduced by using aluminum. In addition, since silver (Ag) has a high light reflectivity, it is suitable for use as an electrode material. In addition, Ag is a transition metal of Group 11. When Ag is used as the cathode of a light-emitting element using Ag in an electron injection layer as one aspect of the present invention, the adhesion between the electrode and the electron injection layer is improved, so it is preferred. In addition, an alloy containing Ag and N (N represents one or more of yttrium (Y), Nd, magnesium (Mg), ytterbium (Yb), Al, Ti, gallium (Ga), zinc (Zn), indium (In), tungsten (W), manganese (Mn), tin (Sn), iron (Fe), Ni, copper (Cu), palladium (Pd), iridium (Ir), and gold (Au)) can also be used. As an alloy containing silver, for example, the following alloys can be cited: an alloy containing silver, palladium, and copper; an alloy containing silver and copper; an alloy containing silver and magnesium; an alloy containing silver and nickel; an alloy containing silver and gold; and an alloy containing silver and ytterbium. In addition to the above materials, transition metals such as tungsten, chromium (Cr), molybdenum (Mo), copper, and titanium can be used.

[0282] In addition, the light obtained from the light-emitting layer is extracted by passing through one or both of the electrode 101 and the electrode 102. Therefore, at least one of the electrode 101 and the electrode 102 is preferably formed of a conductive material having a function of transmitting light. As such a conductive material, a conductive material having a visible light transmittance of 40% or more and 100% or less, preferably 60% or more and 100% or less, and a resistivity of 1×10 -2 Ω·cm or less can be cited.

[0283] In addition, the electrode 101 and the electrode 102 can also be formed of a conductive material having a function of transmitting light and a function of reflecting light. As such a conductive material, a conductive material having a visible light reflectivity of 20% or more and 80% or less, preferably 40% or more and 70% or less, and a resistivity of 1×10 -2A conductive material with a resistivity of less than

[0284] Note that in this specification, etc., as a material having a light-transmitting function, a material having a function of transmitting visible light and having conductivity may be used. For example, there are oxide conductors, oxide semiconductors, or organic conductors containing organic substances represented by ITO as described above. As an organic conductor containing an organic substance, for example, a composite material obtained by mixing an organic compound and an electron donor (donor), a composite material obtained by mixing an organic compound and an electron acceptor (acceptor), etc. may be cited. In addition, inorganic carbon materials such as graphene may also be used. In addition, the resistivity of this material is preferably 1 × 10 5 Ω·cm or less, more preferably 1 × 10 4 Ω·cm or less.

[0285] In addition, one or both of the electrode 101 and the electrode 102 can be formed by laminating a plurality of the above materials.

[0286] In order to improve the light extraction efficiency, a material having a refractive index higher than that of the electrode can be formed in contact with the electrode having a light-transmitting function. As such a material, as long as it has a function of transmitting visible light, it can be a conductive material or a non-conductive material. For example, in addition to the above oxide conductors, oxide semiconductors and organic substances can also be cited. As an organic substance, for example, materials exemplified as a light-emitting layer, a hole injection layer, a hole transport layer, an electron transport layer, or an electron injection layer can be cited. In addition, inorganic carbon materials or metal thin films having a thickness of the order of light transmission can also be used, and a plurality of layers having a thickness of several nm to several tens of nm can also be laminated.

[0287] When the electrode 101 or the electrode 102 is used as a cathode, a material with a small work function (3.8 eV or less) is preferably used.

[0288] When the electrode 101 or the electrode 102 is used as an anode, a material with a large work function (4.0 eV or more) is preferably used.

[0289] The electrode 101 and the electrode 102 may also be a laminate of a conductive material having a function of reflecting light and a conductive material having a function of transmitting light. In this case, the electrode 101 and the electrode 102 have a function of adjusting the optical distance, so that light of a desired wavelength from each light-emitting layer can resonate to enhance the light of that wavelength, which is preferable.

[0290] As a film-forming method for the electrode 101 and the electrode 102, a sputtering method, an evaporation method, a printing method, a coating method, an MBE (Molecular Beam Epitaxy) method, a CVD method, a pulsed laser deposition method, an ALD (Atomic Layer Deposition) method, etc. can be appropriately used.

[0291] "Substrate"

[0292] The light-emitting element according to one embodiment of the present invention can be manufactured on a substrate made of glass, plastic, etc. As the stacking order on the substrate, it can be stacked in order from the electrode 101 side, or can be stacked in order from the electrode 102 side.

[0293] In addition, as a substrate on which the light-emitting element according to one embodiment of the present invention can be formed, for example, glass, quartz, or plastic can be used. Alternatively, a flexible substrate can also be used. A flexible substrate is a substrate that can be bent (flexible), such as a plastic substrate made of polycarbonate or polyarylate. In addition, a thin film, an inorganic vapor deposition thin film, etc. can be used. Note that as long as it plays a role of a support during the manufacturing process of the light-emitting element and the optical element, other materials can be used. Or, as long as it has a function of protecting the light-emitting element and the optical element.

[0294] For example, in the present specification and the like, various substrates can be used to form light-emitting elements. There is no particular limitation on the type of substrate. As examples of such substrates, for example, semiconductor substrates (e.g., single crystal substrates or silicon substrates), SOI substrates, glass substrates, quartz substrates, plastic substrates, metal substrates, stainless steel substrates, substrates having stainless steel foils, tungsten substrates, substrates having tungsten foils, flexible substrates, laminated films, cellulose nanofibers (CNF) or papers or base films containing fibrous materials, etc. can be used. As examples of glass substrates, there are barium borosilicate glass, aluminosilicate glass, soda-lime glass, etc. As examples of flexible substrates, laminated films, base films, etc., the following can be cited. For example, plastics represented by polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polytetrafluoroethylene (PTFE) can be cited. Or, as an example, resins such as acrylic resins can be cited. Or, as an example, polypropylene, polyester, polyvinyl fluoride, or polyvinyl chloride can be cited. Or, as an example, polyamide, polyimide, aromatic polyamide, epoxy resin, inorganic vapor deposition film, papers, etc. can be cited.

[0295] In addition, a flexible substrate can also be used as the substrate, and a light-emitting element can be directly formed on the flexible substrate. Or, a release layer can also be provided between the substrate and the light-emitting element. The release layer can be used when a part or all of the light-emitting element is manufactured on the release layer and then separated from the substrate and transferred to another substrate. At this time, the light-emitting element can also be transferred to a substrate with low heat resistance or a flexible substrate. In addition, as the above release layer, for example, a laminated structure of inorganic films such as a tungsten film and a silicon oxide film or a structure in which a resin film such as polyimide is formed on the substrate can be used.

[0296] That is to say, one substrate can also be used to form a light-emitting element, and then the light-emitting element can be transferred to another substrate. As examples of the substrate to which the light-emitting element is transferred, in addition to the above substrates, cellophane substrates, stone substrates, wood substrates, cloth substrates (including natural fibers (silk, cotton, linen), synthetic fibers (nylon, polyurethane, polyester), or regenerated fibers (acetate fiber, cuprammonium fiber, rayon, regenerated polyester), etc.), leather substrates, rubber substrates, etc. can be cited. By using these substrates, light-emitting elements that are not easily damaged, light-emitting elements with high heat resistance, light-emitting elements that achieve weight reduction, or light-emitting elements that achieve thinning can be manufactured.

[0297] In addition, for example, a field effect transistor (FET) can also be formed on the above substrate, and a light-emitting element 150 can be manufactured on an electrode electrically connected to the FET. Thereby, an active matrix display device that controls the driving of the light-emitting element by the FET can be manufactured.

[0298] The structure shown in this embodiment can be implemented in appropriate combination with the structures shown in other embodiments.

[0299] (Embodiment 2)

[0300] In this embodiment, with reference to FIG. 3, a light-emitting element having a structure different from that of the light-emitting element shown in Embodiment 1 and the light-emitting mechanism of the light-emitting element will be described. Note that in FIG. 3, parts having the same function are shown with the same hatching as Figure 1A and sometimes the reference numerals are omitted. In addition, parts having the same function as those Figure 1A shown are denoted by the same reference numerals, and sometimes their detailed description is omitted. Figure 1A

[0301] <Example 4 of the structure of the light-emitting element>

[0302] FIG. 3 is a cross-sectional schematic view of the light-emitting element 250a and the light-emitting element 250b.

[0303] The light-emitting element 250a and the light-emitting element 250b include electrodes 101, 102, 103, and 104 on the substrate 200. In addition, between the electrode 101 and the electrode 102, between the electrode 102 and the electrode 103, and between the electrode 102 and the electrode 104, at least a light-emitting unit 106, a light-emitting unit 108, and an electron injection layer 130 are included. In addition, a charge generation layer 115 is provided between the light-emitting unit 106 and the light-emitting unit 108. Note that the light-emitting unit 106 and the light-emitting unit 108 may have the same structure or different structures.

[0304] The charge generation layer 115 sandwiched between the light-emitting unit 106 and the light-emitting unit 108 may have, for example, a structure that injects electrons into one light-emitting unit and injects holes into the other light-emitting unit when a voltage is applied between the electrodes 101 and 102. For example, in FIG. 1, when a voltage is applied such that the potential of the electrode 102 is higher than the potential of the electrode 101, the charge generation layer 115 injects electrons into the light-emitting unit 106 and injects holes into the light-emitting unit 108.

[0305] The light-emitting unit 106 includes, for example, a hole injection layer 111, a hole transport layer 112, a light-emitting layer 140, and an electron transport layer 113. In addition, the light-emitting unit 108 includes, for example, a hole injection layer 116, a hole transport layer 117, a light-emitting layer 170, an electron transport layer 118, and an electron injection layer 119.

[0306] ​Here, as shown in FIG. 3, the electron injection layer 130 is preferably adjacent to the electron transport layer 113 and disposed between the light-emitting unit 108 and the electron transport layer 113. In addition, as shown in FIG. 3, the charge generation layer 115 is preferably adjacent to the electron injection layer 130 and disposed between the electron injection layer 130 and the light-emitting unit 108. By adopting such a structure, electrons can be efficiently transported to the light-emitting unit 106.

[0307] In the present embodiment, the electrodes 101, 103, and 104 are anodes and the electrode 102 is a cathode, but the structures of the light-emitting elements 250a and 250b are not limited thereto. That is, the electrodes 101, 103, and 104 can be cathodes and the electrode 102 can be an anode, and the stacking order of the layers between the electrodes can be reversed. In other words, the hole injection layer 111, the hole transport layer 112, the light-emitting layer 140, the electron transport layer 113, and the electron injection layer 130 can be sequentially stacked from the anode side of the light-emitting unit 106, and the hole injection layer 116, the hole transport layer 117, the light-emitting layer 170, the electron transport layer 118, and the electron injection layer 119 can be sequentially stacked from the anode side of the light-emitting unit 108.

[0308] The structures of the light-emitting elements 250a and 250b are not limited to the structure shown in FIG. 3. They at least include the light-emitting layer 140, the light-emitting layer 170, the charge generation layer 115, and the electron injection layer 130, and may include the hole injection layer 111, the hole injection layer 116, the hole transport layer 112, the hole transport layer 117, the electron transport layer 113, the electron transport layer 118, and the electron injection layer 119, or may not include these layers.

[0309] It is only necessary to form each layer between a pair of electrodes according to its function, and it is not limited to the above layers. That is, between a pair of electrode layers, there may also be included layers having the following functions: reducing the injection barrier of holes or electrons; improving the transportability of holes or electrons; hindering the transportability of holes or electrons; or suppressing the quenching phenomenon caused by the electrodes.

[0310] As in the case of the light-emitting unit 108, when the surface on the anode side of the light-emitting unit is in contact with the charge generation layer 115, sometimes the charge generation layer 115 can also function as the hole injection layer of the light-emitting unit 108, so the hole injection layer may not be provided in this light-emitting unit.

[0311] Although a light-emitting element having two light-emitting units is illustrated in FIG. 3, a light-emitting element in which three or more light-emitting units are stacked may also be employed. As shown in the light-emitting elements 250a and 250b, by disposing a plurality of light-emitting units between a pair of electrodes in such a manner that they are separated by a charge generation layer, a light-emitting element can be realized that can emit light with high luminance while maintaining a low current density and has a longer lifespan. In addition, a light-emitting element with low power consumption can also be realized.

[0312] In the light-emitting element 250a, the electrodes 101, 103, and 104 have a function of reflecting visible light, and the electrode 102 has a function of transmitting visible light. In addition, in the light-emitting element 250b, the electrodes 101, 103, and 104 have a function of transmitting visible light, and the electrode 102 has a function of reflecting visible light.

[0313] Therefore, the light emitted by the light-emitting element 250a is emitted to the outside through the electrode 102, and the light emitted by the light-emitting element 250b is emitted to the outside through the electrodes 101, 103, and 104. Note that one aspect of the present invention is not limited thereto, and a light-emitting element that extracts light from both above and below the substrate 200 on which the light-emitting element is formed may also be employed.

[0314] The electrode 101 includes a conductive layer 101a and a conductive layer 101b in contact therewith on the conductive layer 101a. In addition, the electrode 103 includes a conductive layer 103a and a conductive layer 103b in contact therewith on the conductive layer 103a. The electrode 104 includes a conductive layer 104a and a conductive layer 104b in contact therewith on the conductive layer 104a.

[0315] The conductive layers 101b, 103b, and 104b have a function of transmitting visible light. In addition, in the light-emitting element 250a, the conductive layers 101a, 103a, and 104a have a function of reflecting visible light. Further, in the light-emitting element 250b, the conductive layers 101a, 103a, and 104a have a function of transmitting visible light.

[0316] Figure 3A The illustrated light-emitting element 250a and Figure 3B The illustrated light-emitting element 250b includes a partition wall 145 between the region 222B sandwiched by the electrodes 101 and 102, the region 222G sandwiched by the electrodes 102 and 103, and the region 222R sandwiched by the electrodes 102 and 104. The partition wall 145 has insulating properties. The partition wall 145 covers the ends of the electrodes 101, 103, and 104 and includes an opening overlapping with the electrodes. By providing the partition wall 145, the electrodes on the substrate 200 in each region can be divided into island shapes.

[0317] In FIG. 3, an example is shown in which the hole injection layer 111, the hole injection layer 116, the hole transport layer 112, the hole transport layer 117, the light-emitting layer 140, the light-emitting layer 170, the electron transport layer 113, the electron transport layer 118, the electron injection layer 119, the charge generation layer 115, and the electrode 102 are not separately provided in each region, but they may also be separately provided in each region.

[0318] In the light-emitting elements 250a and 250b of one embodiment of the present invention, by applying a voltage between a pair of electrodes (electrode 101 and electrode 102) in the region 222B, between a pair of electrodes (electrode 102 and electrode 103) in the region 222G, and between a pair of electrodes (electrode 102 and electrode 104) in the region 222R, electrons are injected from each cathode into the electron injection layer 119, and holes are injected from the anode into the hole injection layer 111, whereby a current flows. In addition, electrons are injected from the charge generation layer 115 into the electron injection layer 130, and holes are injected from the charge generation layer 115 into the hole injection layer 116. Then, the injected carriers (electrons and holes) recombine to form excitons. In the light-emitting layers 140 and 170 containing a light-emitting material, when the carriers (electrons and holes) recombine to form excitons, the light-emitting material contained in the light-emitting layers 140 and 170 is in an excited state, and thus light emission is obtained from the light-emitting material.

[0319] The light-emitting layers 140 and 170 preferably contain one or more light-emitting materials that emit light of purple, blue, blue-green, green, yellow-green, yellow, yellow-orange, orange, and red.

[0320] The light-emitting layers 140 and 170 may also have a stacked structure of two layers. By using two light-emitting materials having functions of emitting different colors, namely a first compound and a second compound, as the two light-emitting layers respectively, multiple light emissions can be obtained simultaneously. In particular, it is preferable to select the light-emitting materials used in each light-emitting layer such that white or near-white light emission can be obtained by combining the light emitted from the light-emitting layers 140 and 170.

[0321] The light-emitting layers 140 and 170 may also have a stacked structure of three or more layers, and may include a layer that does not contain a light-emitting material.

[0322] The light-emitting element 250a and the light-emitting element 250b include a substrate 220 provided with optical elements 224B, optical elements 224G, and optical elements 224R in the direction in which the light emitted from the regions 222B, 222G, and 222R is extracted. The light emitted from each region passes through each optical element and is emitted to the outside of the light-emitting element. That is, the light emitted from the region 222B passes through the optical element 224B and is emitted, the light emitted from the region 222G passes through the optical element 224G and is emitted, and the light emitted from the region 222R passes through the optical element 224R and is emitted.

[0323] The optical elements 224B, the optical elements 224G, and the optical elements 224R have a function of selectively transmitting light of a specific color in the incident light. For example, the light emitted from the region 222B passes through the optical element 224B and becomes blue light, the light emitted from the region 222G passes through the optical element 224G and becomes green light, and the light emitted from the region 222R passes through the optical element 224R and becomes red light.

[0324] In Figure 3A and Figure 3B the dotted arrows are used to schematically show the blue (B) light, green (G) light, and red (R) light emitted from each region through each optical element. Figure 3A The shown light-emitting element 250a is a top-emitting type light-emitting element, Figure 3B The shown light-emitting element 250b is a bottom-emitting type light-emitting element.

[0325] A light-shielding layer 223 is included between the optical elements. The light-shielding layer 223 has a function of shielding the light emitted from adjacent regions. In addition, a structure in which the light-shielding layer 223 is not provided may be adopted. In addition, one or more of the optical elements 224B, the optical elements 224G, and the optical elements 224R may not be provided. By adopting a structure in which the optical element 224B, the optical element 224G, or the optical element 224R is not provided, the extraction efficiency of the light emitted from the light-emitting element can be improved.

[0326] By using a material obtained by adding an electron acceptor (acceptor) to a hole-transporting material or a material obtained by adding an electron donor (donor) to an electron-transporting material, a charge generation layer 115 can be formed.

[0327] Here, in order to reduce the driving voltage of the light-emitting element, the following structure is preferably adopted: by reducing the electron injection barrier from the charge generation layer 115 to the electron transport layer 113, the electrons generated in the charge generation layer 115 are smoothly injected and transported to the electron transport layer 113. Therefore, it is preferable to provide an electron injection layer 130 between the charge generation layer 115 and the electron transport layer 113. Since the electron injection layer 119 and the electron injection layer 130 require high electron injectability, alkali metals such as lithium (Li) and cesium (Cs) or their compounds, and alkaline earth metals such as calcium (Ca) or their compounds are used for this electron injection layer. However, when this metal and this compound are used for the electron injection layer 130, for example, as shown in FIG. 4, when a voltage is applied between the counter electrode 103 and the electrode 102 and a current flows in the region 222G, sometimes a current also flows in the regions 222B and 222R adjacent to the region 222G through the electron injection layer 130 and the electron transport layer 113, resulting in a phenomenon where light is emitted not only from the region 222G but also from the adjacent regions 222B and 222R (referred to as crosstalk). In addition, in FIG. 4, solid arrows indicate the currents flowing in the regions 222G, 222R, and 222B.

[0328] When crosstalk occurs in the light-emitting element, light is emitted not only from the desired region (e.g., region 222G) but also from other regions (e.g., regions 222B and 222R), which sometimes results in a decrease in the color purity or a decrease in the light emission intensity of the light emitted by the light-emitting elements 250a and 250b.

[0329] One of the reasons for crosstalk is that the alkali metal, alkaline earth metal, or their compound used for the electron injection layer 130 sandwiched between the charge generation layer 115 and the electron transport layer 113 diffuses into the electron transport layer 113, resulting in an increase in the conductivity of the electron transport layer 113 (especially the conductivity in the direction perpendicular to the direction of the applied voltage). In particular, when a metal or its compound with a small atomic number such as Li and Ca is used for the electron injection layer 130, this metal with a small atomic number easily diffuses into the electron transport layer 113. Therefore, in order to suppress crosstalk, it is preferable that the electron injection layer 130 does not contain alkali metals and alkaline earth metals. On the other hand, when alkali metals, alkaline earth metals, or their compounds are not used in the electron injection layer 130, since the electron injection barrier from the charge generation layer 115 to the electron transport layer 113 becomes higher and electrons are not easily injected into the electron transport layer 113, sometimes the driving voltage of the light-emitting element becomes higher or the light emission efficiency decreases.

[0330] Therefore, in order to reduce the driving voltage of the light-emitting element, improve the light-emitting efficiency, and suppress crosstalk, it is preferable to use a metal that has excellent electron injection properties and is not easily diffused into the organic compound when mixed with the organic compound for the electron injection layer 130. The metal that is not easily diffused for the electron injection layer 130 is preferably a metal with a large atomic radius. In addition, it is preferably a metal with a large atomic weight.

[0331] Here, a light-emitting element according to one embodiment of the present invention includes a composite material of an organic compound having a function of interacting with a metal at 3 or 4 teeth and a metal. As the metal, a metal having a relatively large atomic weight or atomic radius belonging to Group 3 to Group 13 can be suitably used. Therefore, one embodiment of the present invention can provide a light-emitting element in which crosstalk is suppressed.

[0332] In particular, since the transition metal has a large atomic weight and is not easily diffused into the organic compound, a light-emitting element in which crosstalk is suppressed can be provided.

[0333] In addition, the light-emitting units 106, 108, and the charge generation layer 115 can be formed by vapor deposition (including vacuum vapor deposition), inkjet, coating, gravure printing, or the like.

[0334] The structure shown in the present embodiment can be implemented in appropriate combination with the structures shown in other embodiments.

[0335] (Embodiment 3)

[0336] In the present embodiment, reference is made to Figure 5A and Figure 5B to describe a light-emitting device using the light-emitting element described in Embodiment 1 and Embodiment 2.

[0337] Figure 5A is a top view showing the light-emitting device, Figure 5B is a cross-sectional view taken along lines A-B and C-D in Figure 5A . The light-emitting device includes a drive circuit unit (source-side drive circuit) 601, a pixel unit 602, and a drive circuit unit (gate-side drive circuit) 603 for controlling the light emission of the light-emitting element, which are shown by dashed lines. In addition, reference numeral 604 is a sealing substrate, reference numeral 625 is a desiccant, reference numeral 605 is a sealant, and the inside surrounded by the sealant 605 is a space 607.

[0338] In addition, the guiding wiring 608 is a wiring for transmitting signals input to the source-side driving circuit 601 and the gate-side driving circuit 603, and receives a video signal, a clock signal, a start signal, a reset signal, etc. from an FPC (Flexible Printed Circuit) 609 serving as an external input terminal. Although only the FPC is illustrated here, a printed wiring board (PWB: Printed Wiring Board) may also be mounted on the FPC. The light-emitting device in this specification includes not only the light-emitting device main body but also the light-emitting device on which the FPC or PWB is mounted.

[0339] Next, refer to Figure 5B to describe the cross-sectional structure of the above-described light-emitting device. A driving circuit portion and a pixel portion are formed on the element substrate 610, and one pixel in the source-side driving circuit 601 and the pixel portion 602, which are the driving circuit portions, is shown here.

[0340] In addition, in the source-side driving circuit 601, a CMOS circuit combining an n-channel TFT 623 and a p-channel TFT 624 is formed. In addition, the driving circuit may also be formed using various CMOS circuits, PMOS circuits, or NMOS circuits. In addition, in the present embodiment, although a driver integrated type in which the driving circuit is formed on the substrate is shown, it is not necessary to adopt this structure, and the driving circuit may be formed externally instead of on the substrate.

[0341] In addition, the pixel portion 602 is formed of a pixel including a switching TFT 611, a current control TFT 612, and a first electrode 613 electrically connected to the drain of the current control TFT 612. In addition, an insulator 614 is formed so as to cover the end portion of the first electrode 613. The insulator 614 may be formed using a positive photosensitive resin film.

[0342] In addition, in order to improve the coverage rate of the film formed on the insulator 614, the upper end portion or the lower end portion of the insulator 614 is formed into a curved surface having a curvature. For example, when a photosensitive acrylic resin is used as the material of the insulator 614, it is preferable that only the upper end portion of the insulator 614 has a curved surface. The radius of curvature of this curved surface is 0.2 μm or more and 0.3 μm or less. In addition, as the insulator 614, a negative photosensitive material or a positive photosensitive material may be used.

[0343] An EL layer 616 and a second electrode 617 are formed on the first electrode 613. Here, as the material of the first electrode 613 used as an anode, a material with a large work function is preferably used. For example, in addition to single-layer films such as ITO films, indium tin oxide films containing silicon, indium oxide films containing 2 wt% or more and 20 wt% or less of zinc oxide, titanium nitride films, chromium films, tungsten films, Zn films, Pt films, etc., a laminated film composed of a titanium nitride film and a film mainly composed of aluminum and a three-layer laminated film composed of a titanium nitride film, a film mainly composed of aluminum, and a titanium nitride film can also be used. Note that when a laminated structure is adopted, the wiring resistance is also low, good ohmic contact can be obtained, and it can be used as an anode.

[0344] In addition, the EL layer 616 is formed by various methods such as vapor deposition using a vapor deposition mask, inkjet method, spin coating method, etc. As the material constituting the EL layer 616, a low molecular compound or a high molecular compound (including oligomers, dendrimers) can also be used.

[0345] In addition, as the material of the second electrode 617 formed on the EL layer 616 and used as a cathode, a material with a small work function (Al, Mg, Li, Ca, or their alloys and compounds (MgAg, MgIn, AlLi, etc.)) is preferably used. Note that when the light generated in the EL layer 616 is to pass through the second electrode 617, a laminate composed of a thin metal film and a transparent conductive film (ITO, indium oxide containing 2 wt% or more and 20 wt% or less of zinc oxide, indium tin oxide containing silicon, zinc oxide (ZnO), etc.) is preferably used as the second electrode 617.

[0346] Furthermore, the light-emitting element 618 is formed by the first electrode 613, the EL layer 616, and the second electrode 617. The light-emitting element 618 preferably has the structure shown in Embodiment 1 and Embodiment 2. In addition, the pixel portion includes a plurality of light-emitting elements, and the light-emitting device of the present embodiment may also include both light-emitting elements having the structure described in Embodiment 1 and Embodiment 2 and light-emitting elements having other structures.

[0347] Furthermore, by bonding the sealing substrate 604 and the element substrate 610 together with a sealant 605, a light-emitting element 618 is provided in a space 607 surrounded by the element substrate 610, the sealing substrate 604, and the sealant 605. In addition, a filler is filled in the space 607, and sometimes an inert gas (nitrogen, argon, etc.), a resin or a drying material, or both a resin and a drying material is used as the filler.

[0348] As the sealant 605, an epoxy resin or glass powder is preferably used. Additionally, these materials are preferably those that minimize the permeation of moisture and oxygen. Furthermore, as the sealing substrate 604, in addition to a glass substrate and a quartz substrate, a plastic substrate made of FRP (Fiber Reinforced Plastics), PVF (polyvinyl fluoride), polyester, acrylic resin, or the like can also be used.

[0349] Through the above method, a light-emitting device using the light-emitting elements described in Embodiment 1 and Embodiment 2 can be obtained.

[0350] <Example 1 of the structure of the light-emitting device>

[0351] In FIG. 6, as an example of the light-emitting device, a light-emitting device in which a light-emitting element that emits white light and a coloring layer (color filter) are formed is shown.

[0352] Figure 6A The substrate 1001, the base insulating film 1002, the gate insulating film 1003, the gate electrodes 1006, 1007, 1008, the first interlayer insulating film 1020, the second interlayer insulating film 1021, the peripheral portion 1042, the pixel portion 1040, the drive circuit portion 1041, the first electrodes 1024W, 1024R, 1024G, 1024B of the light-emitting element, the partition wall 1026, the EL layer 1028, the second electrode 1029 of the light-emitting element, the sealing substrate 1031, the sealant 1032, the red pixel 1044R, the green pixel 1044G, the blue pixel 1044B, the white pixel 1044W, etc. are shown.

[0353] In addition, in Figure 6A and Figure 6B the coloring layers (red coloring layer 1034R, green coloring layer 1034G, blue coloring layer 1034B) are provided on the transparent substrate 1033. Additionally, a black layer (black matrix) 1035 can also be provided. The transparent substrate 1033 provided with the coloring layer and the black layer is aligned and fixed on the substrate 1001. Furthermore, the coloring layer and the black layer are covered by a covering layer 1036. In addition, in Figure 6A there is light that is transmitted to the outside without passing through the coloring layer and light that is transmitted to the outside through each color of the coloring layer. The light that does not pass through the coloring layer becomes white light and the light that passes through the coloring layer becomes red light, blue light, and green light, so an image can be presented with four-color pixels.

[0354] Figure 6B An example is shown in which the red coloring layer 1034R, the green coloring layer 1034G, and the blue coloring layer 1034B are formed between the gate insulating film 1003 and the first interlayer insulating film 1020. As in Figure 6BAs shown, the coloring layer may also be provided between the substrate 1001 and the sealing substrate 1031.

[0355] In addition, although the light-emitting device described above uses a structure in which light is emitted from the side of the substrate 1001 on which the TFT is formed (bottom emission structure), a light-emitting device having a structure in which light is emitted from the side of the sealing substrate 1031 (top emission structure) may also be used.

[0356] <Example 2 of the structure of the light-emitting device>

[0357] Figure 7A and Figure 7B FIG. shows a cross-sectional view of a top-emission type light-emitting device. In this case, a substrate that does not transmit light may be used for the substrate 1001. The process until the connection electrode connecting the TFT and the anode of the light-emitting element is manufactured is carried out in the same manner as that of the bottom-emission type light-emitting device. Then, a third interlayer insulating film 1037 is formed so as to cover the electrode 1022. This insulating film may also have a planarizing function. The third interlayer insulating film 1037 may be formed of the same material as the second interlayer insulating film 1021 or various other materials.

[0358] Although the lower electrodes 1025W, 1025R, 1025G, and 1025B of the light-emitting element are anodes here, they may also be cathodes. In addition, in Figure 7A and Figure 7B In the top-emission type light-emitting device shown, it is preferable that the lower electrodes 1025W, 1025R, 1025G, and 1025B are reflective electrodes. In addition, it is preferable that the second electrode 1029 has a function of emitting light and transmitting light. In addition, it is preferable to adopt a microcavity structure between the second electrode 1029 and the lower electrodes 1025W, 1025R, 1025G, and 1025B to amplify light of a specific wavelength. The EL layer 1028 has the structure as described in Embodiment 1 and Embodiment 2, and has an element structure capable of obtaining white light emission.

[0359] In Figure 6A , Figure 6B , Figure 7A and Figure 7B In, a structure of the EL layer capable of obtaining white light emission may be realized by using a plurality of light-emitting layers or a plurality of light-emitting units, etc. Note that the structure for obtaining white light emission is not limited to this.

[0360] When adopting as Figure 7A and Figure 7BIn the case of the top emission structure shown, a sealing substrate 1031 provided with a coloring layer (red coloring layer 1034R, green coloring layer 1034G, blue coloring layer 1034B) can be used for sealing. A black layer (black matrix) 1035 can be provided between pixels on the sealing substrate 1031. The coloring layer (red coloring layer 1034R, green coloring layer 1034G, blue coloring layer 1034B) and the black layer (black matrix) can also be covered by a covering layer. In addition, a substrate with light transmissivity is used as the sealing substrate 1031.

[0361] In addition, although a structure for full-color display using three colors of red, green, and blue is shown in Figure 7A , as shown in Figure 7B , full-color display can also be performed using four colors of red, green, blue, and white. In addition, the structure for full-color display is not limited to these structures. For example, full-color display can also be performed using four colors of red, green, blue, and yellow.

[0362] The light-emitting element according to one embodiment of the present invention uses a fluorescent material as a guest material. Since the fluorescent material has a sharper spectrum than the phosphorescent material, light emission with high color purity can be obtained. Therefore, by using this light-emitting element in the light-emitting device shown in this embodiment, a light-emitting device with high color reproducibility can be obtained.

[0363] A light-emitting device using the light-emitting element described in Embodiment 1 and Embodiment 2 can be obtained by the above method.

[0364] In addition, this embodiment can be appropriately combined with other embodiments.

[0365] (Embodiment 4)

[0366] In this embodiment, an electronic device and a display device according to one embodiment of the present invention will be described.

[0367] An electronic device and a display device having a flat surface, high luminous efficiency, and high reliability can be manufactured according to one embodiment of the present invention. An electronic device and a display device having a curved surface, high luminous efficiency, and high reliability can be manufactured according to one embodiment of the present invention. Light emission with high color purity can be obtained from the light-emitting element according to one embodiment of the present invention. Therefore, by using this light-emitting element in the light-emitting device shown in this embodiment, an electronic device and a display device with high color reproducibility can be obtained.

[0368] Examples of the electronic device include: a television device; a desktop or notebook personal computer; a display for a computer, etc.; a digital camera; a digital video camera; a digital photo frame; a mobile phone; a portable game machine; a portable information terminal; a sound reproduction device; a large game machine such as a pachinko machine, etc.

[0369] Figure 8A and Figure 8B The portable information terminal 900 shown in the figure includes a housing 901, a housing 902, a display unit 903, a hinge unit 905, etc.

[0370] The housing 901 and the housing 902 are connected together by the hinge unit 905. The portable information terminal 900 can be converted from a folded state ( Figure 8A ) to an unfolded state as shown in Figure 8B . Thus, it has good portability when carried, and due to having a large display area, it has high visibility when in use.

[0371] The portable information terminal 900 is provided with a flexible display unit 903 across the housing 901 and the housing 902 connected by the hinge unit 905.

[0372] The light-emitting device manufactured by one mode of the present invention can be used for the display unit 903. Thus, the portable information terminal can be manufactured with a high yield.

[0373] The display unit 903 can display at least one of file information, still images, moving images, etc. When file information is displayed on the display unit, the portable information terminal 900 can be used as an e-book reader.

[0374] When the portable information terminal 900 is unfolded, the display unit 903 is held in a state with a large radius of curvature. For example, the display unit 903 can be held in such a way that it includes a portion bent with a radius of curvature of 1 mm or more and 50 mm or less, preferably 5 mm or more and 30 mm or less. A part of the display unit 903 is continuously provided with pixels across the housing 901 and the housing 902, so that curved surface display can be performed.

[0375] The display unit 903 is used as a touch panel and can be operated with a finger, a stylus, etc.

[0376] The display unit 903 is preferably composed of a single flexible display. Thus, continuous display can be performed across the housing 901 and the housing 902. In addition, the housing 901 and the housing 902 can also be respectively provided with displays.

[0377] In order to prevent the angle formed by the housing 901 and the housing 902 from exceeding a predetermined angle when the portable information terminal 900 is unfolded, the hinge unit 905 preferably has a locking mechanism. For example, the locking angle (when reaching this angle, it cannot be opened further) is preferably 90° or more and less than 180°, typically, it can be 90°, 120°, 135°, 150°, or 175°, etc. Thus, the convenience, safety, and reliability of the portable information terminal 900 can be improved.

[0378] When the hinge portion 905 has the above-described locking mechanism, excessive force applied to the display portion 903 can be suppressed, and thus damage to the display portion 903 can be prevented. Thereby, a highly reliable portable information terminal can be realized.

[0379] The outer cases 901 and 902 may also include a power button, operation buttons, an external connection port, a speaker, a microphone, and the like.

[0380] Either one of the outer cases 901 and 902 may be provided with a wireless communication module, and data can be transmitted and received through a computer network such as the Internet, a local area network (LAN), or Wi-Fi (registered trademark).

[0381] Figure 8C The illustrated portable information terminal 910 includes an outer case 911, a display portion 912, operation buttons 913, an external connection port 914, a speaker 915, a microphone 916, a camera 917, and the like.

[0382] The light-emitting device manufactured by one mode of the present invention can be used for the display portion 912. Thereby, a portable information terminal can be manufactured with a high yield.

[0383] In the portable information terminal 910, a touch sensor is provided in the display portion 912. Various operations such as making a call or inputting text can be performed by touching the display portion 912 with a finger or a stylus.

[0384] In addition, by operating the operation buttons 913, the power can be turned on and off, or the type of the image displayed on the display portion 912 can be switched. For example, the screen for writing an e-mail can be switched to the main menu screen.

[0385] In addition, by providing a detection device such as a gyro sensor or an acceleration sensor inside the portable information terminal 910, the direction (portrait or landscape) of the portable information terminal 910 can be determined, and the screen display direction of the display portion 912 can be automatically switched. In addition, the switching of the screen display direction can also be performed by touching the display portion 912, operating the operation buttons 913, or inputting sound using the microphone 916.

[0386] The portable information terminal 910 has, for example, one or more functions selected from a telephone, a notebook, and an information reading device. Specifically, the portable information terminal 910 can be used as a smart phone. The portable information terminal 910 can execute various application programs such as a mobile phone, e-mail, reading and editing of articles, music playback, video playback, network communication, and computer games.

[0387] Figure 8DThe illustrated camera 920 includes a housing 921, a display unit 922, operation buttons 923, a shutter button 924, etc. In addition, the camera 920 is equipped with a detachable lens 926.

[0388] The light-emitting device manufactured by one mode of the present invention can be used for the display unit 922. Thus, a camera with high reliability can be manufactured.

[0389] Here, although the camera 920 has a structure that enables the lens 926 to be detached from the housing 921 and exchanged, the lens 926 and the housing 921 can also be formed integrally.

[0390] By pressing the shutter button 924, the camera 920 can capture still images or moving images. In addition, the display unit 922 can also have the function of a touch panel, and imaging can be performed by touching the display unit 922.

[0391] In addition, the camera 920 can also be equipped with an additional flash device and a viewfinder, etc. In addition, these components can also be assembled in the housing 921.

[0392] Figure 9A It is a schematic diagram showing an example of a floor cleaning robot.

[0393] The floor cleaning robot 5100 includes a display 5101 on the top surface, a plurality of cameras 5102, a brush 5103, and operation buttons 5104 on the side surface. Although not shown, tires, a suction port, etc. are provided on the bottom surface of the floor cleaning robot 5100. In addition, the floor cleaning robot 5100 also includes various sensors such as an infrared sensor, an ultrasonic sensor, an acceleration sensor, a piezoelectric sensor, a light sensor, and a gyro sensor. In addition, the floor cleaning robot 5100 includes a wireless communication unit.

[0394] The floor cleaning robot 5100 can automatically move, detect garbage 5120, and suck the garbage from the suction port on the bottom surface.

[0395] In addition, the floor cleaning robot 5100 analyzes the images captured by the camera 5102 and can determine the presence or absence of obstacles such as walls, furniture, or steps. In addition, when an object such as wiring that may be wound around the brush 5103 is detected through image analysis, the rotation of the brush 5103 can be stopped.

[0396] The remaining battery power and the amount of sucked garbage, etc. can be displayed on the display 5101. In addition, the walking path of the floor cleaning robot 5100 can also be displayed on the display 5101. The display 5101 can be a touch panel, and the operation buttons 5104 can be displayed on the display 5101.

[0397] The floor cleaning robot 5100 can communicate with a portable electronic device 5140 such as a smart phone. Images captured by the camera 5102 can be displayed on the portable electronic device 5140. Therefore, the owner of the floor cleaning robot 5100 can also know the situation of the room when going out. In addition, the display content of the display 5101 can be confirmed using a portable electronic device such as a smart phone.

[0398] The light emitting device of one embodiment of the present invention can be used for the display 5101.

[0399] Figure 9B The shown robot 2100 includes an arithmetic unit 2110, an illuminance sensor 2101, a microphone 2102, an upper camera 2103, a speaker 2104, a display 2105, a lower camera 2106, an obstacle sensor 2107, and a moving mechanism 2108.

[0400] The microphone 2102 has a function of detecting the voice of the user and surrounding voices, etc. In addition, the speaker 2104 has a function of emitting sound. The robot 2100 can communicate with the user using the microphone 2102 and the speaker 2104.

[0401] The display 2105 has a function of displaying various information. The robot 2100 can display information desired by the user on the display 2105. A touch panel may be installed on the display 2105. The display 2105 may be a detachable information terminal, and by setting this information terminal at a predetermined position of the robot 2100, charging and data transmission and reception can be performed.

[0402] The upper camera 2103 and the lower camera 2106 have a function of photographing the surrounding environment of the robot 2100. In addition, the obstacle sensor 2107 can detect the presence or absence of an obstacle in front when the robot 2100 moves using the moving mechanism 2108. The robot 2100 can recognize the surrounding environment using the upper camera 2103, the lower camera 2106, and the obstacle sensor 2107 and move safely.

[0403] The light emitting device of one embodiment of the present invention can be used for the display 2105.

[0404] Figure 9CIt is a diagram showing an example of a goggle-type display. The goggle-type display includes, for example, a housing 5000, a display unit 5001, a speaker 5003, an LED lamp 5004, a connection terminal 5006, a sensor 5007 (which has the function of measuring factors such as force, displacement, position, speed, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, electric power, radiation, flow rate, humidity, inclination, vibration, odor, or infrared rays), a microphone 5008, a second display unit 5002, a support unit 5012, headphones 5013, etc.

[0405] The light-emitting device of one aspect of the present invention can be used for the display unit 5001 and the second display unit 5002.

[0406] Figure 10A and Figure 10B It shows a foldable portable information terminal 5150. The foldable portable information terminal 5150 includes a housing 5151, a display area 5152, and a bending part 5153. Figure 10A It shows the portable information terminal 5150 in the unfolded state. Figure 10B It shows the portable information terminal 5150 in the folded state. Although the portable information terminal 5150 has a large display area 5152, by folding the portable information terminal 5150, the portable information terminal 5150 becomes smaller and has good portability.

[0407] The display area 5152 can be folded in half by the bending part 5153. The bending part 5153 is composed of a telescopic member and a plurality of support members. When folding the display area, the telescopic member is stretched, and the bending part 5153 has a curvature radius of 2 mm or more, preferably 5 mm or more.

[0408] In addition, the display area 5152 can also be a touch panel (input / output device) equipped with a touch sensor (input device). The light-emitting device of one aspect of the present invention can be used for the display area 5152.

[0409] This embodiment can be appropriately combined with other embodiments.

[0410] (Embodiment 5)

[0411] In this embodiment, with reference to Figure 11 It shows an example of applying the light-emitting element of one aspect of the present invention to various lighting devices. By using the light-emitting element of one aspect of the present invention, a lighting device with high luminous efficiency and reliability can be manufactured.

[0412] By forming a light-emitting element according to an aspect of the present invention on a flexible substrate, an electronic device or a lighting device having a light-emitting area on a curved surface can be realized.

[0413] In addition, a lighting device using a light-emitting element according to an aspect of the present invention can be applied to automotive lighting, which is provided on a windshield, a ceiling, etc.

[0414] Figure 11 This is an example of using a light-emitting element for an indoor lighting device 8501. In addition, since a large-area light-emitting element can be realized, a large-area lighting device can also be formed. In addition, a lighting device 8502 having a curved light-emitting area can be formed by using a housing having a curved surface. Since the light-emitting element shown in this embodiment is in a film shape, the degree of freedom in the design of the housing is high. Therefore, lighting devices corresponding to various designs can be formed. Also, a large lighting device 8503 can be provided on the interior wall. In addition, a touch sensor can be provided in the lighting device 8501, the lighting device 8502, and the lighting device 8503 to turn on or off the power supply.

[0415] In addition, by using the light-emitting element on the surface side of a table, a lighting device 8504 having the function of a table can be provided. In addition, by using the light-emitting element for a part of other furniture, a lighting device having the function of furniture can be provided.

[0416] As described above, by applying a light-emitting device according to an aspect of the present invention, a lighting device and an electronic device can be obtained. Note that the light-emitting device according to an aspect of the present invention is not limited to the light-emitting device shown in this embodiment and can be applied to lighting devices and electronic devices in various fields.

[0417] The structure shown in this embodiment can be used in appropriate combination with the structures shown in other embodiments.

[0418] [Example 1]

[0419] In this example, manufacturing examples of light-emitting elements 2 to 5 and a comparative light-emitting element 1 according to an aspect of the present invention are shown. Figure 1A A cross-sectional schematic view of the light-emitting element manufactured in this example is shown, and Tables 2 and 3 show the detailed contents of the element structure. In addition, the chemical formulas of the organic compounds used in this example are shown below. Note that the structures and abbreviations of other compounds can be referred to in Embodiment 1 above.

[0420] [Chemical Formula 19]

[0421]

[0422] [Table 2]

[0423]

[0424] [Table 3]

[0425]

[0426] <Manufacture of Light-Emitting Element>

[0427] The manufacturing method of the light-emitting element manufactured in this embodiment is shown below. Comparative light-emitting element 1 is a light-emitting element using LiF, a commonly used Li compound, in the electron injection layer. Light-emitting elements 2 to 5 are light-emitting elements of one aspect of the present invention that use a composite material of an organic compound having a function of interacting with a metal in 3 or 4 teeth and a metal in the electron injection layer.

[0428] <<Manufacture of Comparative Light-Emitting Element 1>>

[0429] As electrode 101, an ITSO film with a thickness of 110 nm is formed on a glass substrate. In addition, the electrode area of electrode 101 is 4 mm 2 (2 mm × 2 mm).

[0430] Next, as hole injection layer 111, DBT3P-II and molybdenum oxide (MoO3) are co-evaporated on electrode 101 at a weight ratio (DBT3P-II:MoO3) of 1:0.5 and a thickness of 25 nm.

[0431] Next, as hole transport layer 112, PCBBiF is evaporated on hole injection layer 111 at a thickness of 20 nm.

[0432] Next, as light-emitting layer 140, 2mDBTBPDBq-II, PCBBiF, and Ir(dmdppr-dmp)2(dpm) are co-evaporated on hole transport layer 112 at a weight ratio (2mDBTBPDBq-II:PCBBiF:Ir(dmdppr-dmp)2(dpm)) of 0.75:0.25:0.08 and a thickness of 40 nm. In addition, in light-emitting layer 140, 2mDBTBPDBq-II and PCBBiF are host materials, and Ir(dmdppr-dmp)2(dpm) is a guest material (phosphorescent compound).

[0433] Next, as electron transport layer 118(1), 2mDBTBPDBq-II is evaporated on light-emitting layer 140 at a thickness of 20 nm.

[0434] Next, as electron transport layer 118(2), NBPhen is evaporated on electron transport layer 118(1) at a thickness of 15 nm.

[0435] As the electron injection layer 130, lithium fluoride (LiF) is vapor-deposited on the electron transport layer 118(2) with a thickness of 1 nm.

[0436] Next, as the electrode 102, aluminum (Al) is formed on the electron injection layer 130 with a thickness of 200 nm.

[0437] Next, heat treatment is performed at 80 °C for 1 hour in the atmosphere without sealing. The comparative light-emitting element 1 is obtained through the above process.

[0438] "Manufacture of Light-Emitting Elements 2 to 5"

[0439] The light-emitting elements 2 to 5 are different from the comparative light-emitting element 1 in the formation process of the electron injection layer 130, and the other processes are the same as those of the comparative light-emitting element 1.

[0440] 〈Manufacture of Light-Emitting Element 2〉

[0441] As the electron injection layer 130, tPy2P and Ag are co-vapor-deposited on the electron transport layer 118(2) with a weight ratio (tPy2P:Ag) of 1:0.3 and a thickness of 5 nm.

[0442] 〈Manufacture of Light-Emitting Element 3〉

[0443] As the electron injection layer 130, 2Py3Tzn and Cu are co-vapor-deposited on the electron transport layer 118(2) with a weight ratio (2Py3Tzn:Cu) of 1:0.3 and a thickness of 5 nm.

[0444] 〈Manufacture of Light-Emitting Element 4〉

[0445] As the electron injection layer 130, Pm3Tzn and Cu are co-vapor-deposited on the electron transport layer 118(2) with a weight ratio (Pm3Tzn:Cu) of 1:0.3 and a thickness of 5 nm.

[0446] 〈Manufacture of Light-Emitting Element 5〉

[0447] As the electron injection layer 130, tPy2P and Co are co-vapor-deposited on the electron transport layer 118(2) with a weight ratio (tPy2P:Co) of 1:0.2 and a thickness of 5 nm.

[0448] <Characteristics of Light-Emitting Elements>

[0449] Next, the element characteristics of the comparative light-emitting element 1 and the light-emitting elements 2 to 5 manufactured as described above were measured. A colorimeter (BM-5A manufactured by Topcon Technohouse) was used for the measurement of brightness and CIE chromaticity. A multi-channel spectrum analyzer (PMA-11 manufactured by Hamamatsu Photonics Co., Ltd.) was used for the measurement of electroemission spectrum.

[0450] Figure 12 , Figure 13 and Figure 14 The current efficiency-luminance characteristics, current-voltage characteristics, and external quantum efficiency-luminance characteristics of the manufactured comparative light-emitting element 1 and light-emitting element 2 to light-emitting element 5 are shown respectively. In addition, the measurement of each light-emitting element was carried out at room temperature (maintained at an atmosphere of 23° C.). In addition, Figure 15 Shown at 2.5 mA / cm 2 Electroemission spectrum when a current of a current density of 100 Å was allowed to flow through each light-emitting element. Note that the measurement was performed at room temperature.

[0451] Table 4 shows 1000 cd / m 2 The device characteristics of the nearby comparative light-emitting element 1 and the light-emitting elements 2 to 5 are shown.

[0452] [Table 4]

[0453]

[0454] like Figure 14 As shown in Table 4, the comparative light-emitting element 1 and the light-emitting elements 2 to 5 all showed high luminous efficiency, that is, the external quantum efficiency exceeded 25%. In addition, the light-emitting elements 2 to 5 of one embodiment of the present invention showed high efficiency equivalent to that of the comparative light-emitting element 1 using LiF, which is a generally used material, for the electron injection layer.

[0455] like Figure 13 As shown in Table 4, the comparative light-emitting element 1 and the light-emitting elements 2 to 5 show good current-voltage characteristics. The light-emitting elements 2 to 5 show the same current-voltage characteristics as the comparative light-emitting element 1, which shows that the composite material of the transition metal with a large work function (4.5 eV or more) such as Cu, Ag, Co and the organic compound having the function of interacting with the metal in the tridentate or tetradentate has a very good electron injection property equivalent to LiF, which is a material generally used in the electron injection layer.

[0456] like Figure 15As shown, comparing Light-emitting element 1 and Light-emitting elements 2 to 5 all show red emission, where the peak wavelength of the electroluminescence spectrum is around 619 nm and the full width at half maximum is about 58 nm. From the obtained electroluminescence spectrum, it can be seen that the above emission comes from the guest material Ir(dmdppr-dmp)2(dpm).

[0457] <Constant current drive test results of the light-emitting element>

[0458] Next, drive tests were performed on Comparative Light-emitting element 1 and Light-emitting elements 2 to 5 under an atmospheric atmosphere and a constant current of 1.0 mA. Figure 16 The results are shown. As described above, Comparative Light-emitting element 1 and Light-emitting elements 2 to 5 are not sealed. From Figure 16 it can be seen that the reliability of Light-emitting elements 2 to 5 is higher than that of Comparative Light-emitting element 1 under an atmospheric atmosphere. In Comparative Light-emitting element 1, a material containing a metal with a small work function is used for the electron injection layer. A metal with a small work function has a higher reactivity with water, and it is possible for moisture to penetrate into the interior of the light-emitting element. Thus, when driving Light-emitting element 1 under an atmospheric atmosphere, the reliability decreases due to moisture. On the other hand, in the light-emitting element of one embodiment of the present invention, a metal with a large work function and a low reactivity with water can be used for the electron injection layer. Therefore, as the light-emitting element of one embodiment of the present invention, a light-emitting element in which moisture is not easily introduced into the interior of the light-emitting element and which has high reliability even when driven under an atmospheric atmosphere can be realized. In addition, Light-emitting elements 3 to 5 show high reliability. Therefore, by using a metal such as Cu or Co with a work function of 4.7 eV or more, a light-emitting element with high reliability can be realized.

[0459] [Example 2]

[0460] In this embodiment, manufacturing examples of Light-emitting elements 7 to 10 and Comparative Light-emitting element 6 of a light-emitting element of one embodiment of the present invention are shown. Figure 1A A cross-sectional schematic diagram of the light-emitting element manufactured in this embodiment is shown, and Tables 5 and 6 show the detailed contents of the element structure. Note that the structures and abbreviations of the organic compounds used in this embodiment can be referred to in the above-described Embodiment 1 and Example 1.

[0461] [Table 5]

[0462]

[0463] [Table 6]

[0464]

[0465] <Manufacture of the light-emitting element>

[0466] The manufacturing method of the light-emitting element manufactured in this embodiment is shown below. The comparative light-emitting element 6 is a light-emitting element in which an electron injection layer is not formed and the electrode is in contact with the electron transport layer. The light-emitting elements 7 to 10 are light-emitting elements using a composite material of an organic compound having a function of interacting with a metal at 3 or 4 teeth and a metal in the electron injection layer according to one aspect of the present invention.

[0467] 《Manufacture of Comparative Light-Emitting Element 6》

[0468] The difference between the comparative light-emitting element 6 and the comparative light-emitting element 1 lies in the formation process of the electron injection layer 130, and the other processes are the same as those of the comparative light-emitting element 1.

[0469] The electron injection layer 130 of the comparative light-emitting element 6 is not formed, and Al is evaporated on the electron transport layer 118 with a thickness of 200 nm as the electrode 102. That is, in the comparative light-emitting element 6, the electrode 102 is in contact with the electron transport layer 118.

[0470] 《Manufacture of Light-Emitting Elements 7 to 10》

[0471] The difference between the light-emitting elements 7 to 10 and the comparative light-emitting element 1 lies in the formation process of the electron injection layer 130, and the other processes are the same as those of the comparative light-emitting element 1.

[0472] <Manufacture of Light-Emitting Element 7>

[0473] As the electron injection layer 130 of the light-emitting element 7, tPy2P and Au are co-evaporated on the electron transport layer 118(2) at a weight ratio (tPy2P:Au) of 1:0.6 and a thickness of 5 nm.

[0474] <Manufacture of Light-Emitting Element 8>

[0475] As the electron injection layer 130 of the light-emitting element 8, 2Py3Tzn and Ag are co-evaporated on the electron transport layer 118(2) at a weight ratio (2Py3Tzn:Ag) of 1:0.5 and a thickness of 5 nm.

[0476] <Manufacture of Light-Emitting Element 9>

[0477] As the electron injection layer 130 of the light-emitting element 9, tPy2P and Cu are co-evaporated on the electron transport layer 118(2) at a weight ratio (tPy2P:Cu) of 1:0.2 and a thickness of 5 nm.

[0478] <Manufacture of Light-Emitting Element 10>

[0479] As the electron injection layer 130 of the light emitting element 10 , 2Py3Tzn and Co were co-evaporated on the electron transport layer 118 ( 2 ) at a weight ratio (2Py3Tzn:Co) of 1:0.3 and a thickness of 5 nm.

[0480] <Characteristics of Light Emitting Element>

[0481] Next, the device characteristics of the comparative light-emitting element 6 and the light-emitting elements 7 to 10 manufactured as described above were measured. The measurement was performed in the same manner as in Example 1.

[0482] Figure 17 , Figure 18 and Figure 19 The current efficiency-luminance characteristics, current-voltage characteristics, and external quantum efficiency-luminance characteristics of the manufactured comparative light-emitting element 6 and light-emitting elements 7 to 10 are shown respectively. In addition, the measurement of each light-emitting element was carried out at room temperature (an atmosphere maintained at 23° C.). In addition, Figure 20 Shown at 2.5 mA / cm 2 Electroemission spectrum when a current of a current density of 100 Å was allowed to flow through each light-emitting element. Note that the measurement was performed at room temperature.

[0483] Table 7 shows 1000 cd / m 2 The device characteristics of the nearby comparative light-emitting element 6 and the light-emitting elements 7 to 10 are shown.

[0484] [Table 7]

[0485]

[0486] Depend on Figure 19 As can be seen from Table 7, the external quantum efficiencies of light-emitting elements 7 to 10 are higher than those of comparative light-emitting element 6. In particular, light-emitting elements 9 and 10 show high external quantum efficiencies exceeding 25%. Figure 18 As shown, the current-voltage characteristics of light-emitting elements 7 to 10 are better than those of comparative light-emitting element 6. In particular, light-emitting element 9 shows excellent current-voltage characteristics. From these results, it can be seen that the electron injection characteristics of light-emitting elements 7 to 10 are better than those of comparative light-emitting element 6.

[0487] In the comparative light-emitting element 6, the electrode is in contact with the electron transport layer. In the light-emitting elements 7 to 10, a metal having a work function higher than that of Al used for the electrode is used for the electron injection layer. Therefore, in view of the work function of the metal, it is estimated that the electron injection characteristics of the comparative light-emitting element 6 are better than those of the light-emitting elements 7 to 10. However, as described above, the electron injection characteristics of the light-emitting elements 7 to 10 are better than those of the comparative light-emitting element 6. Therefore, in the light-emitting element according to one embodiment of the present invention, by using a composite material of an organic compound having a function of interacting with a metal in 3 teeth or 4 teeth and a metal in the electron injection layer, the SOMO of the composite material is formed in the electron injection layer, so that even if a metal having a function with a work function higher than that of the electrode material is used for the electron injection layer, good electron injection characteristics can be obtained.

[0488] As Figure 20 shown, the comparative light-emitting element 6 and the light-emitting elements 7 to 10 both exhibit red light emission, where the peak wavelength of the electroluminescence spectrum is around 619 nm and the full width at half maximum is about 58 nm. It can be seen from the obtained electroluminescence spectrum that the above light emission originates from the guest material Ir(dmdppr-dmp)2(dpm).

[0489] <Constant current drive test results of light-emitting elements>

[0490] Next, the comparative light-emitting element 6 and the light-emitting elements 7 to 10 were subjected to a drive test under an atmospheric atmosphere and a constant current of 1.0 mA. Figure 21 The results are shown. Note that the comparative light-emitting element 6 and the light-emitting elements 7 to 10 are not sealed. From Figure 21 it can be seen that the reliability of the light-emitting elements 7 to 10 is higher than that of the comparative light-emitting element 6. Here, as Figure 18 and Figure 19 shown, the electron injection characteristics of the comparative light-emitting element 6 are lower than those of the light-emitting elements 7 to 10, and the carrier balance in the comparative light-emitting element 6 is poor, which has a negative impact on the reliability. On the other hand, the light-emitting element according to one embodiment of the present invention has high electron injection characteristics and good carrier balance in each light-emitting element, so that a light-emitting element with high reliability can be realized.

[0491] [Example 3]

[0492] In this embodiment, manufacturing examples of the light-emitting elements 12 to 15 and the comparative light-emitting element 11 of the light-emitting element according to one embodiment of the present invention are shown. Figure 1A A cross-sectional schematic diagram of the light-emitting element manufactured in this embodiment is shown, and Tables 8 and 9 show the detailed contents of the element structure. In addition, the chemical formulas of the organic compounds used in this embodiment are shown below. Note that the structures and abbreviations of other compounds can be referred to the above embodiments and Embodiment 1.

[0493] [Chemical formula 20]

[0494]

[0495] [Table 8]

[0496]

[0497] [Table 9]

[0498]

[0499] [Manufacture of light-emitting element]

[0500] The manufacturing method of the light-emitting element manufactured in this embodiment is shown below. Comparative light-emitting element 11 is a light-emitting element using LiF which is a commonly used Li compound in the electron injection layer, and light-emitting elements 12 to 15 are light-emitting elements of one aspect of the present invention using a composite material of an organic compound having a function of interacting with a metal at 3 or 4 teeth and a metal in the electron injection layer.

[0501] [Manufacture of Comparative Light-Emitting Element 11]

[0502] As electrode 101, an ITSO film with a thickness of 70 nm is formed on a glass substrate. In addition, the electrode area of electrode 101 is 4 mm 2 (2 mm × 2 mm).

[0503] Next, as hole injection layer 111, DBT3P-II and molybdenum oxide (MoO3) are co-evaporated on electrode 101 at a weight ratio (DBT3P-II:MoO3) of 1:0.5 and a thickness of 40 nm.

[0504] Next, as hole transport layer 112, PCCP is evaporated on hole injection layer 111 with a thickness of 20 nm.

[0505] Next, as light-emitting layer 140, 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), PCCP and GD270 (manufactured by Jilin OLED Optoelectronic Materials Co., Ltd.) are co-evaporated on hole transport layer 112 at a weight ratio (mPCCzPTzn:PCCP:GD270) of 0.5:0.5:0.1 and a thickness of 40 nm. Note that in light-emitting layer 140, mPCCzPTzn and PCCP are host materials, and GD270 is a guest material (phosphorescent compound).

[0506] Next, as the electron transport layer 118(1), mPCCzPTzn-02 was vapor-deposited on the light-emitting layer 140 with a thickness of 10 nm.

[0507] Next, as the electron transport layer 118(2), NBPhen was vapor-deposited on the electron transport layer 118(1) with a thickness of 15 nm.

[0508] As the electron injection layer 130, LiF was vapor-deposited on the electron transport layer 118(2) with a thickness of 1 nm.

[0509] Next, as the electrode 102, aluminum (Al) was formed on the electron injection layer 130 with a thickness of 200 nm.

[0510] Next, heat treatment was performed at 80 °C for 1 hour in the atmosphere without sealing. The comparative light-emitting element 11 was obtained through the above steps.

[0511] <<Manufacture of Light-Emitting Elements 12 to 15>>

[0512] The difference between the light-emitting elements 12 to 15 and the comparative light-emitting element 11 lies in the formation process of the electron transport layer 118(2) and the electron injection layer 130, while the other processes are the same as those of the comparative light-emitting element 11.

[0513] <<Manufacture of Light-Emitting Element 12>>

[0514] As the electron transport layer 118(2), NBPhen was vapor-deposited on the electron transport layer 118(1) with a thickness of 15 nm. Next, as the electron injection layer 130, tPy2P and Ag were co-vapor-deposited on the electron transport layer 118(2) at a weight ratio (tPy2P:Ag) of 1:0.3 and a thickness of 5 nm.

[0515] <<Manufacture of Light-Emitting Element 13>>

[0516] As the electron transport layer 118(2), NBPhen was vapor-deposited on the electron transport layer 118(1) with a thickness of 10 nm. Next, as the electron injection layer 130, NBPhen and Ag were co-vapor-deposited on the electron transport layer 118(2) at a weight ratio (NBPhen:Ag) of 1:0.3 and a thickness of 5 nm, and then tPy2P and Au were co-vapor-deposited thereon at a weight ratio (tPy2P:Au) of 1:0.6 and a thickness of 5 nm.

[0517] <<Manufacture of Light-Emitting Element 14>>

[0518] As the electron transport layer 118 (2), NBPhen was deposited on the electron transport layer 118 (1) to a thickness of 15 nm. Next, as the electron injection layer 130, 2Py3Tzn and Cu were co-deposited on the electron transport layer 118 (2) at a weight ratio (2Py3Tzn:Cu) of 1:0.3 to a thickness of 5 nm.

[0519] <Manufacturing of Light Emitting Element 15>

[0520] As the electron transport layer 118(2), NBPhen was vapor-deposited on the electron transport layer 118(1) to a thickness of 10 nm. Next, as the electron injection layer 130, NBPhen and Cu were co-evaporated on the electron transport layer 118(2) at a weight ratio (NBPhen:Cu) of 1:0.2 and a thickness of 5 nm, and 2Py3Tzn and Co were co-evaporated thereon at a weight ratio (2Py3Tzn:Co) of 1:0.2 and a thickness of 5 nm.

[0521] <Characteristics of Light Emitting Element>

[0522] Next, the device characteristics of the comparative light-emitting element 11 and the light-emitting elements 12 to 15 manufactured as described above were measured. The measurement was performed in the same manner as in Example 1.

[0523] Figure 22 , Figure 23 and Figure 24 The current efficiency-luminance characteristics, current-voltage characteristics, and external quantum efficiency-luminance characteristics of the manufactured comparative light-emitting element 11 and light-emitting elements 12 to 15 are shown respectively. In addition, the measurement of each light-emitting element was carried out at room temperature (maintained at an atmosphere of 23° C.). In addition, Figure 25 Shown at 2.5 mA / cm 2 Electroemission spectrum when a current of a current density of 100 Å was allowed to flow through each light-emitting element. Note that the measurement was performed at room temperature.

[0524] Table 10 shows 1000 cd / m 2 The device characteristics of the nearby light emitting element 11 and the light emitting elements 12 to 15 are compared.

[0525] [Table 10]

[0526]

[0527] Depend on Figure 24 As shown in Table 10, the light emitting element 11 and the light emitting elements 12 to 15 show the same external quantum efficiency. In addition, the light emitting elements 12 to 14 show a high external quantum efficiency exceeding 20%. Figure 23As shown in Table 10, the light-emitting element 11 and the light-emitting elements 12 to 15 show equal current-voltage characteristics. From these results, it can be seen that the light-emitting elements 12 to 15 have the same electron injection property as the comparative light-emitting element 11 that uses commonly used LiF in the electron injection layer.

[0528] As Figure 25 shown, both the comparative light-emitting element 11 and the light-emitting elements 12 to 15 show green light emission, where the peak wavelength of the electroluminescence spectrum is around 520 nm and the full width at half maximum is about 63 nm. From the obtained electroluminescence spectrum, it can be seen that the above light emission originates from the guest material GD270.

[0529] <Reliability evaluation of light-emitting elements>

[0530] Next, the comparative light-emitting element 11 and the light-emitting elements 12 to 15 were subjected to a constant temperature and humidity storage test. Since each light-emitting element is not sealed, the cathode and the EL layer of the light-emitting element are exposed to the atmosphere of the test environment. Generally, when moisture penetrates into the light-emitting element, black spots (non-light-emitting regions in the light-emitting part) or shrinkage (non-light-emitting regions at the ends of the light-emitting part) are generated, which have a negative impact on the reliability of the light-emitting element. Thus, by performing the constant temperature and humidity storage test, the reliability of the light-emitting element against moisture can be evaluated.

[0531] After the comparative light-emitting element 11 and the light-emitting elements 12 to 15 were respectively placed in a constant temperature bath maintained at 40 °C and a humidity of 90% for 350 hours, the light-emitting states of the respective light-emitting elements were investigated.

[0532] The evaluation of the light-emitting state was carried out by estimating the ratio of the light-emitting area before and after the constant temperature and humidity storage test. Table 11 shows the results.

[0533] [Table 11]

[0534]

[0535] In Table 11, the luminous area ratio (%) = the luminous area after the thermo-hygrostat storage test / the luminous area before the thermo-hygrostat test × 100. As can be seen from Table 11, the comparative light-emitting element 11 using LiF with an alkali metal compound in the electron injection layer deteriorated after the storage test and became non-luminous. On the other hand, the luminous areas of the light-emitting elements 12 to 15 of the light-emitting element according to one embodiment of the present invention are larger than those of the comparative light-emitting element 11. In other words, the light-emitting element according to one embodiment of the present invention has excellent moisture resistance compared with a light-emitting element using a material with a small work function such as an alkali metal in the electron injection layer. This is because the reactivity of a material with a small work function with water is relatively high, and moisture invades the light-emitting element. On the other hand, since the light-emitting element according to one embodiment of the present invention can use a metal with low reactivity with water and a large work function, moisture is not easily introduced into the light-emitting element. Therefore, a light-emitting element with high moisture resistance can be realized.

[0536] As described above, the light-emitting element according to one embodiment of the present invention has excellent electron injection properties, so it is a light-emitting element with a low driving voltage and high luminous efficiency. In addition, since a material with a large work function can be used, it is a light-emitting element with excellent moisture resistance. The structure shown in this embodiment can be used in appropriate combination with other embodiments and modes.

[0537] [Example 4]

[0538] In this embodiment, examples of organic compounds that can be used in the light-emitting element according to one embodiment of the present invention and their synthesis examples will be described.

[0539] Synthesis of 4’-[4-(10-phenyl-9-anthryl)phenyl]-2,2’:6’,2”-terpyridine (abbreviation: PAtPy) (structural formula (200))

[0540] 1.0 g (2.6 mmol) of 4'-(4-bromophenyl)-2,2':6',2''-terpyridine, 0.86 g (2.9 mmol) of 10-phenyl-9-anthraceneboronic acid, 0.85 g (8.0 mmol) of sodium carbonate, 20 mL of toluene, 5 mL of ethanol, and 5 mL of water were placed in a 100 mL three-necked flask. The mixture was degassed while stirring under reduced pressure, and then the atmosphere in the flask was replaced with nitrogen. 65 mg (56 μmol) of tetrakis(triphenylphosphine)palladium(0) was added to the mixture, and the mixture was refluxed at 100 °C for 8 hours under a nitrogen stream. After stirring, the reaction mixture was cooled to room temperature, and the precipitated solid was collected by suction filtration. The chloroform solution of the obtained solid was washed with water, saturated sodium bicarbonate, and saturated brine, and dried using magnesium sulfate. The mixture of the chloroform solution and magnesium sulfate was filtered by gravity, and the filtrate was concentrated to obtain a solid. The methanol suspension of the obtained solid was irradiated with ultrasonic waves, and the solid was collected by suction filtration. Furthermore, the solid was recrystallized using toluene to obtain 1.2 g of the target light red powder with a yield of 81%. The following formula (a-1) shows this synthesis scheme.

[0541] [Chemical formula 21]

[0542]

[0543] 1.2 g of the obtained light red powder was purified by sublimation using the gradient sublimation method. In the sublimation purification, PAtPy was heated at 290 °C under the conditions of a pressure of 4.5 Pa and an argon flow rate of 10 mL / min. After the sublimation purification, 0.55 g of the light red powder of PAtPy was obtained with a recovery rate of 47%.

[0544] Using nuclear magnetic resonance spectroscopy ( 1 1H-NMR), the above-obtained light red powder was measured. The following shows the analysis results.

[0545] 1 1H-NMR (CDCl3, 300 MHz): δ = 7.34 - 7.40 (m, 6H), 7.49 - 7.79 (m, 11H), 7.91 (dt, J = 1.5 Hz, 7.2 Hz, 2H), 8.16 (d, J = 7.8 Hz, 2H), 8.72 - 8.78 (m, 4H), 8.93 (s, 2H).

[0546] Figure 26A and Figure 26B show the 1 1H NMR spectrum of the obtained light red powder. Figure 26B is Figure 26A an enlarged view of the range from 7.0 ppm to 9.5 ppm in . It can be seen from the measurement results that the target PAtPy was obtained.

[0547] [Example 5]

[0548] In this example, examples of organic compounds of a light-emitting element that can be used in one mode of the present invention and synthesis examples thereof will be described.

[0549] <Synthesis of 2-[4’-(2,2’:6’,2”-terpyridin-4’-yl)biphenyl-4-yl]benzoxazole (abbreviation: BOxtPy) (structural formula (201))>

[0550] Place 1.0 g (2.6 mmol) of 4’-(4-bromophenyl)-2,2’:6’,2”-terpyridine, 0.68 g (2.9 mmol) of 4-(benzoxazol-2-yl)phenylboronic acid, 0.62 g (5.8 mmol) of sodium carbonate, 20 mL of toluene, 5 mL of ethanol, and 3 mL of water in a 100 mL three-necked flask. While stirring the mixture under reduced pressure, degas it, and then replace the atmosphere in the flask with nitrogen. Add 63 mg (55 μmol) of tetrakis(triphenylphosphine)palladium(0) to the mixture, and reflux at a temperature of 100 °C for 5 hours under a nitrogen stream. After refluxing, cool the reaction mixture to room temperature, and collect the precipitated solid by suction filtration. Wash the chloroform solution of the obtained solid with water, saturated sodium bicarbonate, and saturated brine, and dry it using magnesium sulfate. Perform gravity filtration on the mixture of the obtained chloroform solution and magnesium sulfate, and concentrate the filtrate to obtain a solid. Recrystallize the obtained solid using toluene to obtain 1.0 g of the target light red powder with a yield of 78%. The following formula (b-1) shows this synthesis scheme.

[0551] [Chemical formula 22]

[0552]

[0553] Perform sublimation purification on 1.0 g of the obtained BOxtPy powder using the gradient sublimation method. In the sublimation purification, heat BOxtPy at a temperature of 280 °C under the conditions of a pressure of 4.4 Pa and an argon flow rate of 10 mL / min. After sublimation purification, obtain 0.64 g of the light red powder of BOxtPy with a recovery rate of 63%.

[0554] Perform measurement on the above-obtained light red powder using nuclear magnetic resonance spectroscopy ( 1 1H-NMR). The following shows the analysis results.

[0555] 11H-NMR (CDCl3, 300 MHz): δ = 7.32 - 7.41 (m, 4H), 7.59 - 7.65 (m, 1H), 7.78 - 7.93 (m, 7H), 8.05 (d, J = 8.4 Hz, 2H), 8.37 (d, J = 7.8 Hz, 2H), 8.70 (d, J = 7.8 Hz, 2H), 8.75 - 8.77 (m, 2H), 8.81 (s, 2H).

[0556] Figure 27A and Figure 27B shows the 1 1H NMR spectrum of the obtained light red powder. Figure 27B is Figure 27A an enlarged view of the range from 7.0 ppm to 9.0 ppm in

[0557] [Example 6]

[0558] In this example, examples of organic compounds for a light-emitting element and synthesis examples thereof, which are applicable to one mode of the present invention, will be described.

[0559] <Synthesis of 4’-{4-[4-(5-Phenyl-1,3,4-oxadiazol-2-yl)phenyl]phenyl}-2,2’:6’,2”-terpyridine (abbreviation: O11tPy) (Structural formula (202))>

[0560] 1.0 g (2.6 mmol) of 4’-(4-Bromophenyl)-2,2’:6’,2”-terpyridine, 0.73 g (2.7 mmol) of 4-(5-Phenyl-1,3,4-oxadiazol-2-yl)phenylboronic acid, 0.71 g (6.7 mmol) of sodium carbonate, 20 mL of toluene, 5 mL of ethanol, and 3 mL of water were placed in a 100 mL three-necked flask. While stirring the mixture under reduced pressure, it was degassed, and the atmosphere in the flask was replaced with nitrogen. 68 mg (59 μmol) of tetrakis(triphenylphosphine)palladium(0) was added to the mixture. The mixture was refluxed at 100 °C for 9 hours under a nitrogen stream. After stirring, the mixture was cooled to room temperature, and the precipitated solid was filtered by suction. The chloroform solution of the obtained solid was washed with water, saturated aqueous sodium bicarbonate solution, and saturated brine, and dried using magnesium sulfate. The mixture was filtered by gravity, and the filtrate was concentrated to obtain a solid. The obtained solid was washed with methanol and then recrystallized using toluene / hexane, whereby a white powder of the target product was obtained in a yield of 0.72 g and a yield of 51%. The following formula (c-1) shows this synthesis scheme.

[0561] [Chemical formula 23]

[0562]

[0563] The obtained 0.71 g of O11tPy powder was sublimated and purified by gradient sublimation method. In the sublimation purification, O11tPy was heated at a temperature of 270 °C under the conditions of a pressure of 4.0 Pa and an argon flow rate of 10 mL / min. After the sublimation purification, 0.29 g of white powder of O11tPy was obtained with a recovery rate of 41%.

[0564] The white powder obtained above was measured by nuclear magnetic resonance spectroscopy ( 1 1H-NMR). The analysis results are shown below.

[0565] 1 1H-NMR (CDCl3, 300 MHz): δ = 7.35 - 7.39 (m, 2H), 7.52 - 7.58 (m, 3H), 7.79 - 7.93 (m, 6H), 8.04 (d, J = 8.4 Hz, 2H), 8.16 - 8.19 (m, 2H), 8.24 (d, J = 8.4 Hz, 2H), 8.69 (d, J = 7.8 Hz, 2H), 8.74 - 8.76 (m, 2H), 8.80 (s, 2H).

[0566] Figure 28A and Figure 28B shows the 1 1H NMR spectrum of the obtained white powder. Figure 28B is Figure 28A an enlarged view of the range from 7.0 ppm to 9.0 ppm in . It can be seen from the measurement results that the target O11tPy was obtained.

[0567] [Example 7]

[0568] In this example, an example of an organic compound for a light-emitting element and a synthesis example thereof, which can be used in one embodiment of the present invention, will be described.

[0569] Synthesis of 9,9’-[5-(2,2’:6’,2”-terpyridin-4’-yl)-1,3-phenylene]bis(9H-carbazole) (abbreviation: Cz2PtPy) (structural formula (203))

[0570] 0.94 g (3.0 mmol) of 4'-bromo-2,2':6',2''-terpyridine, 1.4 g (3.2 mmol) of 3,5-bis(9H-carbazol-9-yl)phenylboronic acid, 0.86 g (6.2 mmol) of sodium carbonate, 30 mL of toluene, 5 mL of ethanol, and 3 mL of water were placed in a 100 mL three-necked flask. The mixture was stirred under reduced pressure to degas, and the atmosphere in the flask was replaced with nitrogen. 72 mg (62 μmol) of tetrakis(triphenylphosphine)palladium(0) was added to the mixture. The mixture was stirred at 80 °C for 7 hours under a nitrogen stream. After stirring, the aqueous layer of the mixture was extracted with toluene, the extraction solution and the organic layer were combined, washed with saturated aqueous sodium bicarbonate and saturated brine, and dried over magnesium sulfate. The mixture was filtered by gravity, and the filtrate was concentrated to obtain a solid. The obtained solid was washed with methanol and then recrystallized from toluene to obtain 1.1 g of the target white powder in a yield of 55%. The following formula (d-1) shows this synthetic scheme.

[0571] [Chemical formula 24]

[0572]

[0573] 0.83 g of the obtained Cz2PtPy powder was sublimated and purified by the gradient sublimation method. In the sublimation purification, Cz2PtPy was heated at 290 °C under the conditions of a pressure of 3.2 Pa and an argon flow rate of 5.0 mL / min. After the sublimation purification, 0.71 g of the white powder of Cz2PtPy was obtained with a recovery rate of 86%.

[0574] The obtained white powder was measured by nuclear magnetic resonance spectroscopy ( 1 1H-NMR). The following shows the analysis results.

[0575] 1 1H-NMR (CDCl3, 300 MHz): δ = 7.31 - 7.37 (m, 6H), 7.47 (dt, J = 0.9 Hz, 7.2 Hz, 4H), 7.59 (d, J = 8.1 Hz, 4H), 7.85 - 7.92 (m, 3H), 8.17 - 8.22 (m, 6H), 8.66 - 8.69 (m, 4H), 8.82 (s, 2H).

[0576] Figure 29A and Figure 29B show the 1 1H NMR spectrum of the obtained white powder. Figure 29B is Figure 29A An enlarged view of the range from 7.0 ppm to 9.0 ppm in. It can be seen from the measurement results that the target Cz2PtPy was obtained.

[0577] [Example 8]

[0578] In this example, examples of organic compounds of a light-emitting element that can be used in one mode of the present invention and synthesis examples thereof will be described.

[0579] [Synthesis of 2,4,6-tris(5-phenyl-2-pyrimidin-2-yl)-1,3,5-triazine (abbreviation: PPm3Tzn) (structural formula (105))]

[0580] Place 0.80 g (4.0 mmol) of 5-phenylpyrimidine-2-carboximidamide, 1.4 g (7.7 mmol) of 2-cyano-5-phenylpyridine, 2 mL of diethylene glycol dimethyl ether, and 1 mL of 1,2,3,4-tetrahydronaphthalene in a 50 mL two-necked flask. Stir the mixture at 180 °C for 29 hours and at 200 °C for 100 hours under a nitrogen stream. After stirring, cool the mixture to room temperature and wash the mixture with ethyl acetate to obtain a brown powder with a yield of 0.82 g. The following formula (e-1) shows this synthesis scheme. In addition, before measuring the 1 1H-NMR, the proton ratio is PPm3Tzn: 5-phenylpyrimidine-2-carboximidamide = 1:1.7, and the target product and the raw material are mixed in the brown powder. In addition, no signal derived from 2-cyano-5-phenylpyridine is observed.

[0581] [Chemical formula 25]

[0582]

[0583] Perform sublimation purification on 0.79 g of the obtained brown powder using the gradient sublimation method. In the sublimation purification, heat at 310 °C under the conditions of a pressure of 3.7 Pa and an argon flow rate of 15 mL / min. After sublimation purification, 0.19 g of a light brown powder of 2,4,6-tris(5-phenyl-2-pyrimidin-2-yl)-1,3,5-triazine is obtained. When measuring the 1 1H-NMR after sublimation purification, the signal derived from 5-phenylpyrimidine-2-carboximidamide disappeared. From this, it can be seen that the target product can be simply purified by using sublimation purification.

[0584] Measure the above-obtained light brown powder by nuclear magnetic resonance spectroscopy ( 1 1H-NMR). The following shows the analysis results.

[0585] 11H-NMR (CDCl3, 300 MHz): δ = 7.52 - 7.63 (m, 9H), 7.73 (dd, J = 1.5 Hz, 7.8 Hz, 6H), 9.35 (s, 6H).

[0586] Figure 30A and Figure 30B shows the 1 1H NMR spectrum of the resulting light brown powder. Figure 30B is Figure 30A an enlarged view of the range from 7.0 ppm to 9.5 ppm in

[0587] [Example 9]

[0588] As a light-emitting element according to one embodiment of the present invention, manufacturing examples of light-emitting elements 16 to 21, comparative light-emitting element 33, and comparative light-emitting element 34, which are one of the following tandem elements, are shown. Figure 31 Fig. shows a cross-sectional schematic view of the light-emitting element manufactured in this example, and Tables 12 to 14 show the detailed contents of the element structure. In addition, the chemical formulas of the organic compounds used in this example are shown below. Note that the structures and abbreviations of other compounds can be referred to in the above examples and Embodiment 1. Note that light-emitting elements 16 to 21 are an example of a light-emitting element, and among elements (also referred to as tandem elements) in which a plurality of EL layers are connected in series with a charge generation layer interposed between a pair of electrodes, as the electron injection layer ( Figure 31 the electron injection layer 114 in Figure 31 ), a composite material of an organic compound having a function of interacting with a metal at 3 or 4 teeth and a metal is used for the charge generation layer 115 in

[0589] [Chemical Formula 26]

[0590]

[0591] [Table 12]

[0592]

[0593]

[0594]

[0595] [Table 13]

[0596]

[0597]

[0598] [Table 14]

[0599]

[0600] <<Manufacture of Light Emitting Element 16>

[0601] As the electrode 101, an ITSO film with a thickness of 110 nm is formed on a glass substrate. The electrode area is 4 mm 2 (2 mm × 2 mm).

[0602] Next, as the hole injection layer 111, DBT3P-II and MoO3 are co-evaporated on the electrode 101 in a weight ratio (DBT3P-II:MoO3) of 1:0.5 and a thickness of 25 nm.

[0603] Next, as the hole transport layer 112, PCBBiF is evaporated on the hole injection layer 111 with a thickness of 20 nm.

[0604] Next, as the light emitting layer 170, 2mDBTBPDBq-II, PCBBiF and Ir(dmdppr-dmp)2(dpm) are co-evaporated on the hole transport layer 112 in a weight ratio (2mDBTBPDBq-II:PCBBiF:Ir(dmdppr-dmp)2(dpm)) of 0.75:0.25:0.08 and a thickness of 40 nm. Note that in the light emitting layer 170, 2mDBTBPDBq-II and PCBBiF are host materials, and Ir(dmdppr-dmp)2(dpm) is a guest material (phosphorescent compound).

[0605] Next, as the electron transport layer 113(1), 2mDBTBPDBq-II is evaporated on the light emitting layer 170 with a thickness of 10 nm. Next, as the electron transport layer 113(2), NBPhen is evaporated with a thickness of 15 nm.

[0606] As the electron injection layer 114, 2,2'-(pyridine-2,6-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 2,6(P-Bqn)2Py) and Cu are co-evaporated on the electron transport layer 113(2) in a weight ratio (2,6(P-Bqn)2Py:Cu) of 1:0.2 and a thickness of 5 nm.

[0607] Next, as the charge generation layer 115, DBT3P-II and MoO3 are co-evaporated on the electron injection layer 114 in a weight ratio (DBT3P-II:MoO3) of 1:0.5 and a thickness of 80 nm.

[0608] Next, as the hole transport layer 119, PCBBiF is evaporated on the charge generation layer 115 with a thickness of 20 nm.

[0609] Next, as the light-emitting layer 140, 2mDBTBPDBq-II, PCBBiF, and Ir(dmdppr-dmp)2(dpm) were co-evaporated on the hole transport layer 119 in a weight ratio of (2mDBTBPDBq-II: PCBBiF: Ir(dmdppr-dmp)2(dpm)) of 0.75:0.25:0.08 and a thickness of 40 nm.

[0610] Next, as the electron transport layer 118(1), 2mDBTBPDBq-II was evaporated on the light-emitting layer 140 with a thickness of 25 nm. Next, as the electron transport layer 118(2), NBPhen was evaporated on the electron transport layer 118(1) with a thickness of 10 nm.

[0611] As the electron injection layer 130, NBPhen and Cu were co-evaporated on the electron transport layer 118(2) in a weight ratio of (NBPhen: Cu) of 1:0.2 and a thickness of 5 nm.

[0612] Next, as the electrode 102, Al was evaporated on the electron injection layer 130 with a thickness of 200 nm.

[0613] Next, in a glove box filled with nitrogen gas, a sealing glass substrate was fixed to the glass substrate on which the organic material was formed using a sealant for organic EL, thereby sealing the light-emitting element 16. Specifically, the sealant was applied around the organic material formed on the glass substrate, and the glass substrate and the glass substrate for sealing were bonded together, and ultraviolet light with a wavelength of 365 nm was irradiated at 6 J / cm 2 and heat treatment was performed at 80 °C for 1 hour. The light-emitting element 16 was obtained through the above process.

[0614] "Manufacture of Light-Emitting Elements 17 to 21, Comparative Light-Emitting Element 33, and Comparative Light-Emitting Element 34"

[0615] Light-emitting elements 17 to 21, comparative light-emitting element 33, and comparative light-emitting element 34 were manufactured in the same manner as the above-described light-emitting element 16. The detailed content of the element structure is shown in Tables 12 to 14, so the detailed content of the manufacturing method is omitted.

[0616] "Measurement of Each Light-Emitting Element"

[0617] The element characteristics of the fabricated light-emitting elements 16 to 21, comparative light-emitting element 33, and comparative light-emitting element 34 were measured. In the measurement of luminance and CIE chromaticity, a color luminance meter (BM-5A manufactured by Topcon Technohouse Corporation) was used. In the measurement of electroluminescence spectra, a multi-channel spectral analyzer (PMA-11 manufactured by Hamamatsu Photonics K.K.) was used.

[0618] Figure 32 , Figure 33 , Figure 34 and Figure 35 respectively show the current efficiency-luminance characteristics, current-voltage characteristics, power efficiency-luminance characteristics, and external quantum efficiency-luminance characteristics of the fabricated light-emitting elements 16 to 21, comparative light-emitting element 33, and comparative light-emitting element 34. In addition, the measurement of each light-emitting element was performed at room temperature (atmosphere maintained at 23 °C). In addition, Figure 36 shows the electroluminescence spectrum when a current is passed through each light-emitting element at a current density of 2.5 mA / cm 2 . Note that the measurement was performed at room temperature.

[0619] Table 15 shows the element characteristics of the light-emitting elements 16 to 21, comparative light-emitting element 33, and comparative light-emitting element 34 near 1000 cd / m 2 .

[0620] [Table 15]

[0621]

[0622] As Figure 36 shown, the peak wavelengths of the electroluminescence spectra of the light-emitting elements 16 to 21, comparative light-emitting element 33, and comparative light-emitting element 34 are all around 620 nm. From this, it can be seen that the light-emitting elements 16 to 21, comparative light-emitting element 33, and comparative light-emitting element 34 exhibit luminescence derived from Ir(dmdppr-dmp)2(dpm) of the host material contained in each light-emitting element.

[0623] As Figure 35 and Table 15 show, the light-emitting elements 16 to 21 all show a very high luminous efficiency equal to that of the comparative light-emitting element 33, that is, the external quantum efficiency exceeds 50%. In addition, as Figure 32 and Figure 34As shown, high current efficiency and high power efficiency are shown. On the other hand, the external quantum efficiency of the comparative light-emitting element 34 is low, i.e., 27.2%, and a sufficiently high efficiency for a series element cannot be obtained. From these results, it can be seen that the electron injection properties of the light-emitting elements 16 to 21 are equal to those of the comparative light-emitting element 33 using Li2O of a commonly used Li compound in the electron injection layer of the charge generation layer in contact between the EL layers.

[0624] As Figure 33 shown in Table 15, the light-emitting elements 16 to 21 have a lower driving voltage and good current-voltage characteristics compared to the comparative light-emitting element 33 and the comparative light-emitting element 34. Also, it can be seen that the driving voltage of the comparative light-emitting element 34 is very high, and there is a problem with the electron injection property from the charge generation layer. From these results, it can be seen that the electron injection properties of the light-emitting elements 16 to 21 are equal to those of the comparative light-emitting element 33 using Li2O of a commonly used Li compound in the electron injection layer of the charge generation layer in contact between the EL layers. Therefore, even when a composite material of an organic compound having a function of interacting with a metal at 3 or 4 teeth and a metal is used as the electron injection layer of the charge generation layer in contact between the EL layers in a series element, good driving voltage characteristics are shown.

[0625] <Constant Current Driving Test Results of Light-Emitting Elements>

[0626] Next, a driving test was conducted on the light-emitting element 18, the light-emitting element 19, the comparative light-emitting element 33, and the comparative light-emitting element 34 at room temperature and a constant current of 1.0 mA. Figure 52 The results are shown. It can be Figure 52 seen that the reliability of the light-emitting element 18 and the light-emitting element 19 is higher than that of the comparative light-emitting element 33 and the comparative light-emitting element 34. From these results, it can be seen that the reliability of the light-emitting element 18 and the light-emitting element 19 is higher than that of the comparative light-emitting element 33 using Li2O of a commonly used Li compound in the electron injection layer of the charge generation layer and the comparative light-emitting element 34 that does not include the electron injection layer of the charge generation layer. Therefore, by using a composite material of an organic compound having a function of interacting with a metal at 3 or 4 teeth and a metal as the electron injection layer of the charge generation layer in contact between the EL layers in a series element, a light-emitting element with high reliability can be realized.

[0627] As described above, the light-emitting element according to one embodiment of the present invention has excellent electron injection properties, so it is a light-emitting element with a low driving voltage and high luminous efficiency. In addition, since a material with a large work function can be used, it is a light-emitting element with excellent moisture resistance and high reliability. The structure shown in this embodiment can be used in appropriate combination with other embodiments and modes.

[0628] [Example 10]

[0629] The light-emitting element as one aspect of the present invention shows a manufacturing example of light-emitting elements 22 to 25. FIG. 1 shows a cross-sectional schematic view of the light-emitting element manufactured in this embodiment, and Table 16 shows the detailed content of the element structure. Note that for the structures and abbreviations of other compounds, reference can be made to the above-described embodiments and Embodiment 1. Note that in light-emitting elements 22 to 25, as the metal of the composite material of the organic compound and the metal having the function of interacting with a three-tooth or four-tooth metal, In belonging to Group 13 metals is used.

[0630] [Table 16]

[0631]

[0632]

[0633] 《Manufacture of Light-Emitting Element 22》

[0634] The difference between light-emitting element 22 and comparative light-emitting element 1 lies in the formation process of the electron injection layer 130, and other processes are the same as those of comparative light-emitting element 1.

[0635] As the electron injection layer 130 of light-emitting element 22, tPy2P and In are co-evaporated on the electron transport layer 118(2) in a weight ratio (tPy2P:In) of 1:0.4 and a thickness of 5 nm.

[0636] 《Manufacture of Light-Emitting Element 23》

[0637] The difference between light-emitting element 23 and comparative light-emitting element 1 lies in the formation processes of the electron transport layer 118(2) and the electron injection layer 130, and other processes are the same as those of comparative light-emitting element 1.

[0638] As the electron transport layer 118(2) of light-emitting element 23, NBPhen is evaporated with a thickness of 10 nm on the electron transport layer 118(1).

[0639] Next, as the electron injection layer 130(1), NBPhen and Ag are co-evaporated on the electron transport layer 118(2) in a weight ratio (NBPhen:Ag) of 1:0.3 and a thickness of 5 nm. Next, as the electron injection layer 130(2), 2Py3Tzn and In are co-evaporated on the electron injection layer 130(1) in a weight ratio (2Py3Tzn:In) of 1:0.6 and a thickness of 5 nm.

[0640] 《Manufacture of Light-Emitting Elements 24 and 25》

[0641] The light-emitting element 24 and the light-emitting element 25 are different from the light-emitting element 23 in the step of forming the electron injection layer 130 ( 2 ), and the other steps are the same as those of the light-emitting element 23 .

[0642] <Manufacturing of Light Emitting Element 24>

[0643] As the electron injection layer 130 ( 2 ) of the light-emitting element 24 , 2,6(P-Bqn)2Py and In were co-evaporated on the electron transport layer 130 ( 1 ) in a weight ratio (2,6(P-Bqn)2Py:In) of 1:0.3 and a thickness of 5 nm.

[0644] <Manufacturing of Light Emitting Element 25>

[0645] As the electron injection layer 130 ( 2 ) of the light emitting element 25 , 2,6(NP-PPm)2Py and In were co-evaporated on the electron transport layer 130 ( 1 ) at a weight ratio (2,6(NP-PPm)2Py:In) of 1:0.3 and a thickness of 5 nm.

[0646] In the light-emitting elements 22 to 25, cathodes were manufactured in the same manner as in the comparative light-emitting element 1, and then heat treated at 80°C for 1 hour in the atmosphere without sealing.

[0647] <Measurement of Each Light Emitting Element>

[0648] The device characteristics of the light-emitting elements 22 to 25 manufactured as described above were measured. A colorimeter (BM-5A manufactured by Topcon Technohouse) was used for the measurement of brightness and CIE chromaticity. A multi-channel spectrum analyzer (PMA-11 manufactured by Hamamatsu Photonics Co., Ltd.) was used for the measurement of electroemission spectra.

[0649] Figure 37 , Figure 38 , Figure 39 and Figure 40 The current efficiency-brightness characteristics, current-voltage characteristics, power efficiency-brightness characteristics, and external quantum efficiency-brightness characteristics of the manufactured light-emitting elements 22 to 25 are shown respectively. In addition, the measurement of each light-emitting element is carried out at room temperature (maintained at an atmosphere of 23° C.). In addition, Figure 41 Shown at 2.5 mA / cm 2 Electroemission spectrum when a current of a current density of 100 Å was allowed to flow through each light-emitting element. Note that the measurement was performed at room temperature.

[0650] Table 17 shows 1000 cd / m 2 The device characteristics of the light emitting elements 22 to 25 in the vicinity.

[0651] [Table 17]

[0652]

[0653] As Figure 41 shown, the peak wavelengths of the field emission spectra of light-emitting elements 22 to 25 are all around 615 nm. From this, it can be seen that light-emitting elements 22 to 25 exhibit luminescence from Ir(dmdppr-dmp)2(dpm) of the host material contained in each light-emitting element.

[0654] As Figure 40 and Table 17 show, light-emitting elements 22 to 25 all show very high luminous efficiency, that is, the external quantum efficiency exceeds 25%. As Figure 37 and Figure 39 shown, high current efficiency and high power efficiency are shown. Therefore, it can be seen that In is preferably used as the metal for the composite material of an organic compound and a metal having a function of interacting with a metal with 3 teeth or 4 teeth.

[0655] In addition, as Figure 38 shown, light-emitting elements 22 to 25 show good current-voltage characteristics. Therefore, it can be seen that In is preferably used as the metal for the composite material of an organic compound and a metal having a function of interacting with a metal with 3 teeth or 4 teeth.

[0656] As described above, the light-emitting element of one embodiment of the present invention has excellent electron injection properties, so it is a light-emitting element with a low driving voltage and high luminous efficiency. In addition, since a material with a large work function can be used, it is a light-emitting element with excellent moisture resistance. The structure shown in this embodiment can be used in appropriate combination with other embodiments and modes.

[0657] [Example 11]

[0658] Examples of manufacturing light-emitting elements 26 to 28, which are one of the light-emitting elements of one embodiment of the present invention, are shown. FIG. 1 shows a cross-sectional schematic view of the light-emitting element manufactured in this embodiment, and Table 18 shows the detailed content of the element structure. In addition, the chemical formulas of the organic compounds used in this embodiment are shown below. Note that the structures and abbreviations of other compounds can be referred to the above embodiments and Mode 1. Note that light-emitting elements 26 to 28 are an example of light-emitting elements, in which an organic compound having a triazine skeleton or a bipyridine skeleton is used as the organic compound for the composite material of an organic compound and a metal having a function of interacting with a metal with 3 teeth or 4 teeth. Note that in this embodiment, the composite material of an organic compound and a metal having a function of interacting with a metal with 3 teeth or 4 teeth is used for the electron injection layer 130.

[0659] [Chemical Formula 27]

[0660]

[0661] [Table 18]

[0662]

[0663] "Manufacture of Light-Emitting Elements 26 to 28"

[0664] The difference between light-emitting elements 26 to 28 and comparative light-emitting element 1 lies in the formation process of the electron injection layer 130, while the other processes are the same as those of comparative light-emitting element 1.

[0665] As the electron injection layer 130 of light-emitting element 26, PPm3Tzn and Cu are co-evaporated on the electron transport layer 118(2) in a weight ratio of (PPm3Tzn:Cu) of 1:0.2 and a thickness of 5 nm. PPm3Tzn is an example of an organic compound having a triazine skeleton. PPm3Tzn can also be said to be an organic compound having a pyrimidine skeleton.

[0666] As the electron injection layer 130 of light-emitting element 27, 2,2'-(2,2'-bipyridine-6,6'-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 6,6'(P-Bqn)2BPy) and Ag are co-evaporated on the electron transport layer 118(2) in a weight ratio of (6,6'(P-Bqn)2BPy:Ag) of 1:0.3 and a thickness of 5 nm. 6,6'(P-Bqn)2BPy is an example of an organic compound having a bipyridine skeleton. 6,6'(P-Bqn)2BPy can also be said to be an organic compound having a quinazoline skeleton.

[0667] As the electron injection layer 130 of light-emitting element 28, 6,6'(P-Bqn)2BPy and Cu are co-evaporated on the electron transport layer 118(2) in a weight ratio of (6,6'(P-Bqn)2BPy:Cu) of 1:0.3 and a thickness of 5 nm.

[0668] In light-emitting elements 26 to 28, the cathode is manufactured in the same manner as comparative light-emitting element 1, and then heat treatment is performed at 80 °C for 1 hour in the atmosphere without sealing.

[0669] <Measurement of Each Light-Emitting Element>

[0670] Next, the device characteristics of the light-emitting elements 26 to 28 manufactured as described above were measured. A colorimeter (BM-5A manufactured by Topcon Technohouse) was used for the measurement of brightness and CIE chromaticity. A multi-channel spectrum analyzer (PMA-11 manufactured by Hamamatsu Photonics Co., Ltd.) was used for the measurement of electroemission spectrum.

[0671] Figure 42 , Figure 43 , Figure 44 and Figure 45 The current efficiency-brightness characteristics, current-voltage characteristics, power efficiency-brightness characteristics, and external quantum efficiency-brightness characteristics of the manufactured light-emitting elements 26 to 28 are shown respectively. In addition, the measurement of each light-emitting element is carried out at room temperature (maintained at 23° C. atmosphere). In addition, Figure 46 Shown at 2.5 mA / cm 2 Electroemission spectrum when a current of a current density of 100 Å was allowed to flow through each light-emitting element. Note that the measurement was performed at room temperature.

[0672] Table 19 shows 1000 cd / m 2 Element characteristics of the nearby light emitting elements 26 to 28.

[0673] [Table 19]

[0674]

[0675] like Figure 46 As shown, the peak wavelengths of the electric field emission spectra of light-emitting elements 26 to 28 are all near 618 nm, from which it can be seen that light-emitting elements 26 to 28 exhibit luminescence originating from Ir(dmdppr-dmp)2(dpm) of the guest material contained in each light-emitting element.

[0676] like Figure 45 As shown in Table 19, light emitting elements 26 to 28 all show very high luminous efficiency, that is, the external quantum efficiency exceeds 29%. Figure 42 and Figure 44 As shown, high current efficiency and high power efficiency are shown. Therefore, it can be seen that as an organic compound for a composite material of an organic compound and a metal having a function of interacting with a metal in a tridentate or tetradentate, an organic compound having a triazine skeleton (or a pyrimidine skeleton) or a bipyridine skeleton (or a quinazoline skeleton) is preferably used.

[0677] like Figure 43As shown, light-emitting elements 26 to 28 exhibit good current-voltage characteristics. Therefore, it is understood that as an organic compound of a composite material of an organic compound and a metal having a function of interacting with a metal at 3 or 4 teeth, an organic compound having a triazine skeleton (or pyrimidine skeleton) or a bipyridine skeleton (or quinazoline skeleton) is preferably used.

[0678] As described above, the light-emitting element of one aspect of the present invention has excellent electron injection properties, so it is a light-emitting element with a low driving voltage and high luminous efficiency. In addition, since a material with a large work function can be used, it is a light-emitting element with excellent moisture resistance. The structure shown in this embodiment can be used in appropriate combination with other embodiments and modes.

[0679] [Example 12]

[0680] Manufacturing examples of light-emitting elements 29 to 32, which are one of the light-emitting elements of one aspect of the present invention, are shown. FIG. 1 shows a cross-sectional schematic diagram of the light-emitting element manufactured in this embodiment, and Table 20 shows the detailed content of the element structure. In addition, the chemical formulas of the organic compounds used in this embodiment are shown below. Note that the structures and abbreviations of other compounds can be referred to the above embodiments and Mode 1. Note that light-emitting elements 29 to 32 are an example of a light-emitting element, in which an organic compound having a pyridine skeleton is used as an organic compound of a composite material of an organic compound and a metal having a function of interacting with a metal at 3 or 4 teeth. Note that in this embodiment, a composite material of an organic compound and a metal having a function of interacting with a metal at 3 or 4 teeth is used for the electron injection layer 130.

[0681] [Table 20]

[0682]

[0683]

[0684] 《Manufacture of Light-Emitting Elements 29 to 32》

[0685] The difference between light-emitting elements 29 to 32 and comparative light-emitting element 1 lies in the formation process of the electron injection layer 130, and other processes are the same as those of comparative light-emitting element 1.

[0686] As the electron injection layer 130 of the light-emitting element 29, 2,6(P-Bqn)2Py and Ag are co-evaporated on the electron transport layer 118 (2) in a weight ratio (2,6(P-Bqn)2Py:Ag) of 1:0.3 and a thickness of 5 nm. 2,6(P-Bqn)2Py is an example of an organic compound having a pyridine skeleton. 2,6(P-Bqn)2Py can also be said to be an organic compound having a quinazoline skeleton.

[0687] As the electron injection layer 130 of the light-emitting element 30, 2,6(P-Bqn)2Py and Cu were co-evaporated on the electron transport layer 118 (2) in a weight ratio (2,6(P-Bqn)2Py:Cu) of 1:0.2 and a thickness of 5 nm.

[0688] As the electron injection layer 130 of the light-emitting element 31, 2,6'(NP-PPm)2Py and Ag are co-evaporated on the electron transport layer 118(2) in a weight ratio (2,6'(NP-PPm)2Py:Ag) of 1:0.3 and a thickness of 5 nm. 2,6'(NP-PPm)2Py is an example of an organic compound having a pyridine skeleton. 2,6'(NP-PPm)2Py can also be said to be an organic compound having a pyrimidine skeleton.

[0689] In Light-Emitting Elements 29 to 32, cathodes were manufactured in the same manner as in Comparative Light-Emitting Element 1, and then heat treated at 80°C for 1 hour in the atmosphere without sealing.

[0690] <Measurement of Each Light-Emitting Element>

[0691] The device characteristics of the light-emitting elements 29 to 32 manufactured as described above were measured. A colorimeter (BM-5A manufactured by Topcon Technohouse) was used for the measurement of brightness and CIE chromaticity. A multi-channel spectrum analyzer (PMA-11 manufactured by Hamamatsu Photonics Co., Ltd.) was used for the measurement of electroemission spectra.

[0692] Figure 47 , Figure 48 , Figure 49 and Figure 50 The current efficiency-brightness characteristics, current-voltage characteristics, power efficiency-brightness characteristics, and external quantum efficiency-brightness characteristics of the manufactured light-emitting elements 29 to 32 are shown respectively. In addition, the measurement of each light-emitting element is carried out at room temperature (maintained at 23° C. atmosphere). In addition, Figure 51 Shown at 2.5 mA / cm 2 Electroemission spectrum when a current of a current density of 100 Å was allowed to flow through each light-emitting element. Note that the measurement was performed at room temperature.

[0693] Table 21 shows the device characteristics of light-emitting elements 29 to 32 near 2 1000 cd / m 2 .

[0694] [Table 21]

[0695]

[0696] As Figure 51 shown, the peak wavelengths of the field emission spectra of light-emitting elements 29 to 32 are all near 618 nm. Thus, it can be seen that light-emitting elements 29 to 32 exhibit luminescence from Ir(dmdppr-dmp)2(dpm) of the host material contained in each light-emitting element.

[0697] As Figure 50 and Table 21 show, light-emitting elements 29 to 32 all show very high luminous efficiency, that is, the external quantum efficiency exceeds 28%. As Figure 47 and Figure 49 shown, high current efficiency and high power efficiency are shown. Therefore, it can be seen that as an organic compound for a composite material of an organic compound and a metal having a function of interacting with a metal at 3 teeth or 4 teeth, an organic compound having a pyridine skeleton (pyrimidine skeleton or quinazoline skeleton) is preferably used.

[0698] As Figure 48 shown, light-emitting elements 29 to 32 show good current-voltage characteristics. Therefore, it can be seen that as an organic compound for a composite material of an organic compound and a metal having a function of interacting with a metal at 3 teeth or 4 teeth, an organic compound having a triazine skeleton (or pyrimidine skeleton) or a bipyridine skeleton (or quinazoline skeleton) is preferably used.

[0699] As described above, the light-emitting element of one aspect of the present invention has excellent electron injectability, so it is a light-emitting element with a low driving voltage and a high luminous efficiency. In addition, since a material with a large work function can be used, it is a light-emitting element with excellent moisture resistance. The structure shown in this embodiment can be used in appropriate combination with other embodiments and modes.

[0700] [Symbol Explanation]

[0701] 100: EL layer, 101: electrode, 101a: conductive layer, 101b: conductive layer, 102: electrode, 103: electrode, 103a: conductive layer, 103b: conductive layer, 104: electrode, 104a: conductive layer, 104b: conductive layer, 106: light-emitting unit, 108: light-emitting unit, 110: EL layer, 111: hole injection layer, 112: hole transport layer, 113: electron transport layer, 115: charge generation layer, 116: hole injection layer, 117: hole transport layer, 118: electron transport layer, 119: electron injection layer, 127: buffer layer, 129: charge generation layer, 130: electron injection layer, 131: compound, 132: metal, 133: compound, 140: light-emitting layer, 145: partition wall, 150: light-emitting element, 152: light-emitting element, 154: light-emitting element, 170: light-emitting layer, 200: substrate, 220: substrate, 222B: region, 222G: region, 222R: region, 223: light-shielding layer, 224B: optical element, 224G: optical element, 224R: optical element, 250a: light-emitting element, 250b: light-emitting element, 601: source-side drive circuit, 602: pixel portion, 603: gate-side drive circuit, 604: sealing substrate, 605: sealant, 607: space, 608: wiring, 610: element substrate, 611: TFT for switch, 612: TFT for current control, 613: electrode, 614: insulator, 616: EL layer, 617: electrode, 618: light-emitting element, 623: n-channel TFT, 624: p-channel TFT, 900: portable information terminal, 901: housing, 902: housing, 903: display unit, 905: hinge portion, 910: portable information terminal, 911: housing, 912: display unit, 913: operation button, 914: external connection port, 915: speaker, 916: microphone, 917: camera, 920: camera, 921: housing, 922: display unit, 923: operation button, 924: shutter button, 926: lens, 1001: substrate, 1002: base insulating film, 1003: gate insulating film, 1006: gate electrode, 1007: gate electrode, 1008: gate electrode, 1020: interlayer insulating film, 1021: interlayer insulating film, 1022: electrode, 1024B: electrode, 1024G: electrode, 1024R: electrode, 1024W: electrode, 1025B: lower electrode, 1025G: lower electrode, 1025R: lower electrode, 1025W: lower electrode, 1026: partition wall, 1028: EL layer, 1029: electrode, 1031: sealing substrate, 1032: sealant, 1033: base material, 1034B: coloring layer, 1034G: coloring layer, 1034R: coloring layer, 1036: protective layer, 1037: interlayer insulating film, 1040: pixel portion1041: Driving circuit section, 1042: Peripheral section, 2100: Robot, 2101: Illuminance sensor, 2102: Microphone, 2103: Upper camera, 2104: Speaker, 2105: Display, 2106: Lower camera, 2107: Obstacle sensor, 2108: Moving mechanism, 2110: Arithmetic unit, 5000: Housing, 5001: Display section, 5002: Display section, 5003: Speaker, 5004: LED lamp, 5005: Operation key, 5006: Connection terminal, 5007: Sensor, 5008: Microphone, 5012: Support section, 5013: Headphone, 5100: Floor cleaning robot, 5101: Display, 5102: Camera, 5103: Brush, 5104: Operation button, 5120: Garbage, 5140: Portable electronic device, 5150: Portable information terminal, 5151: Housing, 5152: Display area, 5153: Bending section, 8501: Lighting device, 8502: Lighting device, 8503: Lighting device, 8504: Lighting device.

Claims

1. A light-emitting element, comprising: A light-emitting layer between an anode and a cathode; And A first layer between the light-emitting layer and the cathode, Wherein the first layer contains a first organic compound and a metal, The metal belongs to any one of Groups 3 to 13 in the periodic table, The first organic compound includes a substituted or unsubstituted heteroaromatic ring having 1 or more and 30 or less carbon atoms, The heteroaromatic ring contains nitrogen, The nitrogen in the first organic compound has a function of interacting with the metal in a tridentate or tetradentate manner, The first organic compound and the metal are a combination that forms SOMO, And the first organic compound is represented by general formulas (G3-1) and (G3-3), In the formula, R 1 to R 8 each independently represents hydrogen, an alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms which is substituted or unsubstituted, an aryl group having 6 or more and 25 or less carbon atoms which is substituted or unsubstituted, or a heteroaryl group having 3 or more and 30 or less carbon atoms which is substituted or unsubstituted. Ar represents hydrogen, an alkyl group having 1 to 4 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, an aryl group having 6 or more and 60 or less carbon atoms, or a heteroaryl group having 2 or more and 60 or less carbon atoms.

2. A light-emitting element, comprising: A light-emitting layer between an anode and a cathode; And A first layer between the light-emitting layer and the cathode, Wherein the first layer contains a first organic compound and a metal, The metal belongs to any one of Groups 3 to 13 in the periodic table, The first organic compound includes a substituted or unsubstituted heteroaromatic ring having 1 or more and 30 or less carbon atoms, The heteroaromatic ring contains nitrogen, The nitrogen in the first organic compound has a function of interacting with the metal in a tridentate or tetradentate manner, The first organic compound and the metal are a combination that forms SOMO, The first organic compound is represented by general formula (G3-2), In the formula, R 1 to R 8 each independently represents hydrogen, an alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms which is substituted or unsubstituted, an aryl group having 6 or more and 25 or less carbon atoms which is substituted or unsubstituted, or a heteroaryl group having 3 or more and 30 or less carbon atoms which is substituted or unsubstituted. Ar represents any one of structural formulas (Ar-1) to (Ar-41) and (Ar-43) to (Ar-48), 3. The light-emitting element according to claim 1, wherein the first organic compound is represented by general formulas (G4-1) and (G4-3), [Chemical formula 5] In the formula, Ar represents hydrogen, an alkyl group having 1 to 4 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, an aryl group having 2 or more and 60 or less carbon atoms, or a heteroaryl group having 3 or more and 60 or less carbon atoms.

4. The light-emitting element according to claim 2, wherein the first organic compound is represented by general formula (G4-2), 5. The light-emitting element according to claim 2, wherein the first organic compound is represented by any one of structural formulas (100) and (102), 6. The light-emitting element according to claim 1, wherein the first organic compound is represented by structural formula (103), 7. The light-emitting element according to claim 1 or 2, wherein the work function of the metal is 4.0 eV or more and 5.3 eV or less.

8. The light-emitting element according to claim 1 or 2, wherein the metal is a transition metal.

9. The light-emitting element according to claim 1 or 2, wherein the metal belongs to any one of Groups 5, 7, 9, and 11 in the periodic table.

10. The light-emitting element according to claim 1 or 2, wherein the metal belongs to Group 11 in the periodic table.

11. The light-emitting element according to claim 1 or 2, wherein the metal is Ag or Cu.

12. The light-emitting element according to claim 1 or 2, wherein the LUMO energy level of the first organic compound is -3.6 eV or more and -2.3 eV or less.

13. The light-emitting element according to claim 1 or 2, further comprising a second layer between the cathode and the first layer, wherein the second layer contains a second organic compound including an electron-deficient heteroaromatic ring.

14. The light-emitting element according to claim 13, wherein the LUMO energy level of the second organic compound is lower than the energy level of the SOMO.

15. The light-emitting element according to claim 1 or 2, wherein the first layer does not contain an alkali metal and an alkaline earth metal.

16. The light-emitting element according to claim 1 or 2, wherein the molar ratio of the metal in the first layer to the first organic compound is 0.2 or more and 0.8 or less.

17. The light-emitting element according to claim 1 or 2, wherein the cathode contains the metal.

18. The light-emitting element according to claim 1 or 2, wherein the cathode is in contact with the first layer.

19. The light-emitting element according to claim 1 or 2, wherein the work function of the metal is equal to or higher than the work function of the metal contained in the cathode.

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