Light-emitting element

Abstract

Provided is a light-emitting element having a low driving voltage and high reliability. The light-emitting element includes 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 containing an organic compound and a metal. The metal belongs to any one of group 3 to group 13 in the periodic table. The organic compound and the metal are a SOMO-forming combination.

Description

This application is a divisional application of the Chinese patent application titled “Light-emitting elements, light-emitting devices, electronic devices and lighting devices” with national application number 201880080618.X after the PCT international application with international application number PCT / IB2018 / 060157 and international application date December 17, 2018 entered the Chinese stage. Technical Field

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

[0002] Note that one embodiment of the present invention is not limited to the above-mentioned technical field. The technical field of one embodiment of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. In addition, one embodiment of the present invention relates to a process, a machine, a product, or a composition of matter. Therefore, specifically, as examples of the technical field of one embodiment of the present invention disclosed in this specification, 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 can be cited. Background Art

[0003] In recent years, research and development of light-emitting devices utilizing electroluminescence (EL) have become increasingly intense. The basic structure of these light-emitting devices consists of a layer containing a light-emitting substance (EL layer) sandwiched between a pair of electrodes. Light from the light-emitting substance is generated by applying a voltage between the electrodes.

[0004] Because the light-emitting element is self-luminous, a display device using it has advantages such as good visibility, no need for a backlight, and low power consumption. Furthermore, the display device has the following advantages: it can be made thin and light, and has a fast response speed.

[0005] Generally, in EL elements, an electron injection layer is provided between the cathode and the light-emitting layer to reduce the driving voltage. To reduce the electron injection barrier between the cathode and the EL layer, metals with low work functions, such as alkali metals or alkaline earth metals represented by lithium (Li) or calcium (Ca), or compounds of these metals are used as this electron injection layer (e.g., Patent Document 1). [Prior technical literature] [Patent Document]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2001-102175 Summary of the Invention Technical problem to be solved by the invention

[0007] Metals or metal compounds with low work functions are highly reactive with oxygen or water, making them difficult to handle. Furthermore, when these metals or metal compounds are used in light-emitting elements, they are affected by oxygen or water, sometimes resulting in a decrease in the luminous efficiency of the light-emitting element, an increase in the driving voltage, or a reduction in reliability. Therefore, it is necessary to develop an electron injection layer that is less susceptible to the effects of oxygen or water and has a low electron injection barrier between the cathode and the EL layer.

[0008] In view of the above problems, an object of one embodiment of the present invention is to provide a light-emitting element with a low driving voltage. An object of one embodiment of the present invention is to provide a light-emitting element with high moisture resistance. An object of one embodiment of the present invention is to provide a light-emitting element with high oxygen resistance. An object of one embodiment of the present invention is to provide a light-emitting element with reduced power consumption. An object of one embodiment of the present invention is to provide a light-emitting element with high reliability. An object of one embodiment of the present invention is to provide a novel light-emitting element. An object of one embodiment of the present invention is to provide a novel semiconductor device. An object of one embodiment of the present invention is to provide an organic compound that can be used for a light-emitting element with high moisture resistance.

[0009] One embodiment of the present invention provides an electronic device and a lighting device having high moisture resistance using the above-mentioned light-emitting element. Another embodiment of the present invention provides a light-emitting device having reduced power consumption using the above-mentioned light-emitting element. Another embodiment of the present invention provides a light-emitting device having a long service life using the above-mentioned light-emitting element.

[0010] Note that the description of the above-mentioned purpose does not prevent the existence of other purposes. One embodiment of the present invention does not necessarily need to achieve all of the above-mentioned purposes. In addition, purposes other than the above-mentioned purpose can be known and extracted from the description of the specification, etc. Means of solving technical problems

[0011] As described above, there is a demand for the development of light-emitting elements with high moisture resistance and electron injection characteristics. Therefore, there is a demand for the development of light-emitting elements that do not use metals with small work functions.

[0012] Therefore, one embodiment 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, wherein the first layer includes a first organic compound and a metal, the metal belonging to any one of Groups 3 to 13 of the periodic table, the first organic compound includes a substituted or unsubstituted heteroaromatic ring having 1 to 30 carbon atoms, the heteroaromatic ring containing nitrogen, the nitrogen in the first organic compound having 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).

[0013] Another embodiment of the present invention is a light-emitting element comprising 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, wherein the first layer comprises a first organic compound and a metal, the metal belonging to any one of Groups 3 to 13 of the periodic table, the first organic compound comprising 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 having a function of interacting with the metal in a tridentate or tetradentate manner, and the first organic compound and the metal forming a SOMO.

[0014] In the above structure, the first organic compound is preferably an organic compound represented by the general formula (G0).

[0015] [Chemical Formula 1]

[0016] In the general formula (G0), A 1 、A 2 and A 3 Each independently represents a substituted or unsubstituted heteroaromatic ring having 1 to 30 carbon atoms, A 1 、A 2 and A 3 They may also form a condensed ring.

[0017] In the above structure, the first organic compound is preferably an organic compound represented by general formula (G1).

[0018] [Chemical Formula 2]

[0019] In the general formula (G1), X 1 To X 6 Each independently represents carbon (C) or nitrogen (N), wherein 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 aromatic hydrocarbon group having 6 to 25 carbon atoms, or a substituted or unsubstituted heteroaromatic hydrocarbon group having 3 to 30 carbon atoms, and R1 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 aromatic hydrocarbon group having 6 to 25 carbon atoms, or a substituted or unsubstituted heteroaromatic hydrocarbon group having 3 to 30 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 aromatic hydrocarbon group having 6 to 60 carbon atoms, or a heteroaromatic hydrocarbon group having 2 to 60 carbon atoms.

[0020] In the above structure, the first organic compound is preferably an organic compound represented by general formula (G2).

[0021] [Chemical Formula 3]

[0022] In the general formula (G2), X 1 and X 2 Each independently represents carbon (C) or nitrogen (N), wherein 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 aromatic hydrocarbon group having 6 to 25 carbon atoms, or a substituted or unsubstituted heteroaromatic hydrocarbon group having 3 to 30 carbon atoms, and 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 aromatic hydrocarbon group having 6 to 25 carbon atoms, or a substituted or unsubstituted heteroaromatic hydrocarbon group having 3 to 30 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 aromatic hydrocarbon group having 6 to 60 carbon atoms, or a heteroaromatic hydrocarbon group having 2 to 60 carbon atoms.

[0023] In the above structure, the first organic compound is preferably an organic compound represented by any one of General Formulae (G3-1) to (G3-3).

[0024] [Chemical Formula 4]

[0025] In the general formulas (G3-1) to (G3-3), 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 aromatic hydrocarbon group having 6 to 25 carbon atoms, or a substituted or unsubstituted heteroaromatic hydrocarbon group having 3 to 30 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 aromatic hydrocarbon group having 6 to 60 carbon atoms, or a heteroaromatic hydrocarbon group having 2 to 60 carbon atoms.

[0026] In the above structure, the first organic compound is preferably an organic compound represented by any one of General Formulae (G4-1) to (G4-3).

[0027] [Chemical Formula 5]

[0028] 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 aromatic hydrocarbon group having 2 to 60 carbon atoms, or a heteroaromatic hydrocarbon group having 2 to 60 carbon atoms.

[0029] 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).

[0030] [Chemical Formula 6]

[0031] In the above structure, the work function of the metal is preferably 4.0 eV or more and 5.3 eV or less.

[0032] In the above structure, the LUMO (Lowest Unoccupied Molecular Orbital) energy level of the first organic compound is preferably not less than -3.6 eV and not more than -2.3 eV.

[0033] In the above structure, the metal is preferably a transition metal, more preferably a metal belonging to any of Groups 5, 7, 9 and 11, further preferably a transition metal belonging to Group 11, and even more preferably Ag or Cu.

[0034] In the above structure, the heteroaromatic ring preferably includes a substituted or unsubstituted electron-deficient heteroaromatic ring, and more preferably includes any one of a pyridine ring, a diazine ring, and a triazine ring.

[0035] In the above structure, it is preferred to further include a second layer between the cathode and the first layer, wherein the second layer includes a second organic compound including an electron-deficient heteroaromatic ring.

[0036] In the above structure, the second organic compound preferably has a LUMO energy level lower than a SOMO energy level.

[0037] In the above structure, the first layer preferably does not contain alkali metals and alkaline earth metals.

[0038] 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.

[0039] In the above structure, the cathode preferably comprises the same metal as the first layer.

[0040] Another embodiment of the present invention is an organic compound represented by structural formulas (200) to (203).

[0041] [Chemical Formula 7]

[0042] Another embodiment of the present invention is an electronic device comprising: a display device of each of the above structures; and at least one of a housing and a touch sensor. Another embodiment of the present invention is a lighting device comprising: a light-emitting element of each of the above structures; and at least one of a housing and a touch sensor. In addition, one embodiment of the present invention includes not only a light-emitting device having a light-emitting element within its scope, but also 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). In addition, the following display module is also an embodiment 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 the light-emitting element; a display module in which a printed circuit board is provided at the end of the TCP; or a display module in which an IC (Integrated Circuit) is directly mounted on the light-emitting element by a COG (Chip On Glass) method. Effects of the Invention

[0043] According to one embodiment of the present invention, a light-emitting element with a low driving voltage can be provided. According to one embodiment of the present invention, a light-emitting element with high moisture resistance can be provided. According to one embodiment of the present invention, a light-emitting element with high oxygen resistance can be provided. According to one embodiment of the present invention, a light-emitting element with reduced power consumption can be provided. According to one embodiment of the present invention, a light-emitting element with high reliability can be provided. According to one embodiment of the present invention, a novel light-emitting element can be provided. According to one embodiment of the present invention, a novel semiconductor device can be provided. According to one embodiment of the present invention, an organic compound that can be used for a light-emitting element with high moisture resistance can be provided.

[0044] According to one embodiment of the present invention, an electronic device and a lighting device with high moisture resistance using the above-mentioned light-emitting element can be provided. According to one embodiment of the present invention, a light-emitting device with reduced power consumption using the above-mentioned light-emitting element can be provided. According to one embodiment of the present invention, a light-emitting device with a long service life using the above-mentioned light-emitting element can be provided.

[0045] 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 effects can be understood and extracted from the description of the specification, drawings, claims, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] FIG1 is a schematic cross-sectional view illustrating a light-emitting element according to one embodiment of the present invention and a diagram showing energy level correlation of an electron injection layer. FIG2 is a schematic cross-sectional view illustrating a light-emitting element according to one embodiment of the present invention. FIG3 is a schematic cross-sectional view illustrating a light-emitting element according to one embodiment of the present invention. FIG4 is a schematic cross-sectional view illustrating a light-emitting element according to one embodiment of the present invention. [Fig. 5] A plan view and a schematic cross-sectional view illustrating a display device according to one embodiment of the present invention. FIG6 is a schematic cross-sectional view illustrating a display device according to one embodiment of the present invention. FIG7 is a schematic cross-sectional view illustrating a display device according to one embodiment of the present invention. [Figure 8] A diagram illustrating an electronic device according to one embodiment of the present invention. [Figure 9] A diagram illustrating an electronic device according to one embodiment of the present invention. [Figure 10] A diagram illustrating an electronic device according to one embodiment of the present invention. [ Figure 11 ]A diagram illustrating a lighting device according to one embodiment of the present invention. [ Figure 12 ]A diagram illustrating the current efficiency-luminance characteristics of the light-emitting element of the embodiment. [ Figure 13 ]A diagram illustrating the current-voltage characteristics of the light-emitting element of the embodiment. [ Figure 14 ]A diagram illustrating the external quantum efficiency-luminance characteristics of the light-emitting element of the embodiment. [ Figure 15 ]A diagram illustrating the electric field emission spectrum of the light-emitting element of the embodiment. [ Figure 16 ] A diagram illustrating the reliability test results of the light-emitting element of the embodiment. [ Figure 17]A diagram illustrating the current efficiency-luminance characteristics of the light-emitting element of the embodiment. [ Figure 18 ]A diagram illustrating the current-voltage characteristics of the light-emitting element of the embodiment. [ Figure 19 ]A diagram illustrating the external quantum efficiency-luminance characteristics of the light-emitting element of the embodiment. [ Figure 20 ]A diagram illustrating the electric field emission spectrum of the light-emitting element of the embodiment. [ Figure 21 ] A diagram illustrating the reliability test results of the light-emitting element of the embodiment. [ Figure 22 ]A diagram illustrating the current efficiency-luminance characteristics of the light-emitting element of the embodiment. [ Figure 23 ]A diagram illustrating the current-voltage characteristics of the light-emitting element of the embodiment. [ Figure 24 ] A diagram illustrating the external quantum efficiency-luminance characteristics of the light-emitting element of the embodiment. [ Figure 25 ]A diagram illustrating the electric field emission spectrum of the light-emitting element of the embodiment. Fig. 26 is a diagram illustrating NMR spectra of compounds of Examples. Fig. 27 is a diagram illustrating NMR spectra of compounds of Examples. Fig. 28 is a diagram illustrating NMR spectra of compounds of Examples. Fig. 29 is a diagram illustrating NMR spectra of compounds of Examples. Fig. 30 is a diagram illustrating NMR spectra of compounds of Examples. [ Figure 31 ] A schematic cross-sectional view illustrating a light-emitting element according to one embodiment of the present invention. [ Figure 32 ]A diagram illustrating the current efficiency-luminance characteristics of the light-emitting element of the embodiment. [ Figure 33 ]A diagram illustrating the current-voltage characteristics of the light-emitting element of the embodiment. [ Figure 34 ] A diagram illustrating the power efficiency-luminance characteristics of the light-emitting element of the embodiment. [ Figure 35 ] A diagram illustrating the external quantum efficiency-luminance characteristics of the light-emitting element of the embodiment. [ Figure 36 ]A diagram illustrating the electric field emission spectrum of the light-emitting element of the embodiment. [ Figure 37 ]A diagram illustrating the current efficiency-luminance characteristics of the light-emitting element of the embodiment. [ Figure 38 ]A diagram illustrating the current-voltage characteristics of the light-emitting element of the embodiment. [ Figure 39 ] A diagram illustrating the power efficiency-luminance characteristics of the light-emitting element of the embodiment. [ Figure 40 ] A diagram illustrating the external quantum efficiency-luminance characteristics of the light-emitting element of the embodiment. [ Figure 41 ]A diagram illustrating the electric field emission spectrum of the light-emitting element of the embodiment. [ Figure 42 ]A diagram illustrating the current efficiency-luminance characteristics of the light-emitting element of the embodiment. [ Figure 43 ]A diagram illustrating the current-voltage characteristics of the light-emitting element of the embodiment. [ Figure 44 ] A diagram illustrating the power efficiency-luminance characteristics of the light-emitting element of the embodiment. [ Figure 45 ] A diagram illustrating the external quantum efficiency-luminance characteristics of the light-emitting element of the embodiment. [ Figure 46 ]A diagram illustrating the electric field emission spectrum of the light-emitting element of the embodiment. [ Figure 47 ]A diagram illustrating the current efficiency-luminance characteristics of the light-emitting element of the embodiment. [ Figure 48 ]A diagram illustrating the current-voltage characteristics of the light-emitting element of the embodiment. [ Figure 49 ] A diagram illustrating the power efficiency-luminance characteristics of the light-emitting element of the embodiment. [ Figure 50 ] A diagram illustrating the external quantum efficiency-luminance characteristics of the light-emitting element of the embodiment. [ Figure 51 ]A diagram illustrating the electric field emission spectrum of the light-emitting element of the embodiment. [ Figure 52 ] A diagram illustrating the reliability test results of the light-emitting element of the embodiment. Modes for Carrying Out the Invention

[0047] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited to the following description, and its embodiments and details may be modified in various forms without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the contents described in the embodiments shown below.

[0048] In addition, for ease of understanding, the positions, sizes, and ranges of various structures shown in the drawings and the like may not necessarily represent their actual positions, sizes, and ranges. Therefore, the disclosed invention is not necessarily limited to the positions, sizes, and ranges disclosed in the drawings and the like.

[0049] In addition, in this specification and other documents, ordinal numbers such as "first" and "second" are used for convenience, but these numbers do not necessarily indicate the order of steps or the order of stacking. Therefore, for example, "first" can be appropriately replaced with "second" or "third" to provide a more detailed description. Furthermore, the ordinal numbers used in this specification and other documents may not match the ordinal numbers used to designate one embodiment of the present invention.

[0050] Note that in this specification and the like, when describing the configuration of the invention using drawings, reference numerals are used in common to indicate the same components in different drawings.

[0051] In addition, in this specification, "film" and "layer" may be interchanged. For example, "conductive layer" may be replaced with "conductive film". Also, for example, "insulating film" may be replaced with "insulating layer".

[0052] (Implementation 1) In this embodiment, a light-emitting element which is one embodiment of the present invention is described with reference to FIG. 1 .

[0053] <Structural Example 1 of Light-Emitting Element> Figure 1A 1 is a schematic cross-sectional view of a light-emitting element 150 according to one embodiment of the present invention.

[0054] 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 .

[0055] also, Figure 1A 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 and the electron injection layer 130 .

[0056] Note that although in this embodiment, electrode 101 of a pair of electrodes is described as an anode and electrode 102 as a cathode, the structure of light-emitting element 150 is not limited to this. In other words, electrode 101 may serve as a cathode and electrode 102 as an anode, with the layers stacked in reverse order between the electrodes. In other words, the hole injection layer 111, hole transport layer 112, light-emitting layer 140, electron transport layer 118, and electron injection layer 130 may be stacked in this order from the anode side.

[0057] The structure of the EL layer 100 is not limited to Figure 1A The structure shown includes at least a light-emitting layer 140 and an electron injection layer 130 , and may include a hole injection layer 111 , a hole transport layer 112 and an electron transport layer 118 or may not include these layers.

[0058] The EL layer between the pair of electrodes may be formed with layers that fulfill desired functions and is not limited to the layers described above. Specifically, the EL layer between the pair of electrodes may include layers that have functions such as reducing the injection barrier for holes or electrons, improving hole or electron transport, hindering hole or electron transport, or suppressing quenching caused by the electrodes.

[0059] The light-emitting layer 140 preferably includes a host material and a guest material (light-emitting material).

[0060] As the main material, it is preferred to use one or both of a material having the function of transporting holes (hole transport properties) (hole transport materials) and a material having the function of transporting electrons (electron transport properties) (electron transport materials). Materials having both hole transport properties and electron transport properties may also be used.

[0061] When the host material is a combination of an electron-transporting material and a hole-transporting material (a 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 1:9 to 9:1. Furthermore, this structure makes it easy to control the carrier balance and, therefore, the carrier recombination zone.

[0062] As the guest material, a light-emitting compound may 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.

[0063] 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 preferred to provide an electron injection layer 130 between the light-emitting layer 140 and the electrode 102. In existing light-emitting elements, the electron injection layer 130 uses a metal material having an alkali metal or alkaline earth metal with a small work function. However, since the metal material with a small work function has high reactivity with oxygen and water, when the electron injectability decreases due to reaction with oxygen or water in the light-emitting element, it becomes a cause of a decrease in luminous efficiency, an increase in driving voltage, a decrease in element life, the occurrence of shrinkage (non-luminous area at the end of the light-emitting portion), etc., sometimes leading to a decrease in the characteristics of the light-emitting element or a decrease in reliability. In other words, the metal material with a small work function becomes the cause of element degradation. Therefore, in order to suppress the decrease in the characteristics of the light-emitting element or the decrease in reliability, the light-emitting element preferably does not have an alkali metal or an alkaline earth metal.

[0064] On the other hand, although metals with large work functions have low reactivity with oxygen and water, when metals with large work functions are used for the electron injection layer 130, the electron injection barrier between the light-emitting layer 140 and the electrode 102 becomes larger, resulting in problems such as an increase in the driving voltage of the light-emitting element and a decrease in the luminous efficiency.

[0065] The present inventors have discovered that by allowing an organic compound capable of interacting with a metal at a tridentate or quadridentate position to interact with a transition metal to form a SOMO, and using a composite material of an organic compound and metal forming this SOMO in the electron injection layer, the electron injection barrier from the cathode to the light-emitting layer can be lowered, thereby achieving a light-emitting element with high moisture resistance. In other words, the present inventors have discovered that the electron injection layer 130 can be formed without using alkali metals or alkaline earth metals.

[0066] Therefore, a light-emitting element according to one embodiment 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 in a tridentate or tetradentate manner and a metal is used for an electron injection layer.

[0067] SOMO is formed by the interaction of the organic compound and the metal. The SOMO is an orbital originating from the unpaired electrons possessed by the metal and is also distributed on the orbital of the organic compound. Thus, it can be seen that the electronic orbit of the metal interacts with the electronic orbit of the organic compound. In addition, in order to efficiently interact with the organic compound and the metal, the organic compound preferably contains many atoms that interact. Because the organic compound containing many atoms that interact easily interacts with the metal, SOMO can be easily formed by mixing the organic compound with the metal. Therefore, the organic compound used in the light-emitting element of one embodiment of the present invention preferably has the function of interacting with the metal in 3-dentate or 4-dentate. In addition, when the organic compound containing many atoms that interact and the metal form 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, SOMO can also be formed by interacting with a metal with a large work function. Therefore, the organic compound used in the light-emitting element of one embodiment of the present invention preferably has the function of interacting with the metal in 3-dentate or 4-dentate.

[0068] As the atom interacting with the metal, a heteroatom having a non-shared electron pair in an organic compound can be cited. For example, oxygen (O), nitrogen (N), sulfur (S), phosphorus (P) can be cited, of which nitrogen is preferably preferred. Nitrogen has a high electronegativity and easily interacts with metals. In addition, because the organic compound having a function of interacting with a metal in a 3-dentate or 4-dentate light-emitting element of one embodiment of the present invention is used for an electron injection layer, it is preferably electron transportable. Therefore, the organic compound is preferably an organic compound in which conjugation extends over the entire molecule. Here, nitrogen can form a conjugated bond in the organic compound, and thus, by using nitrogen in a molecule, especially in a 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, it is more preferred that the heteroaromatic ring is an even-numbered ring such as a 6-membered ring or an 8-membered ring. In this structure, the non-shared electron pair on nitrogen has nothing to do with conjugation, so it is easy to interact with the metal.

[0069] In order for an organic compound having a tridentate or tetradentate metal interaction function to interact with a metal to form a SOMO, the sum of the electron numbers of the organic compound and the metal is preferably an odd number. Therefore, when the organic compound has an even number of electrons, the metal is preferably from an odd-numbered group in the periodic table. Furthermore, when the organic compound has an odd number of electrons, the metal is preferably from an even-numbered group in the periodic table.

[0070] As the organic compound having a function of interacting with the metal in a tridentate or tetradentate manner, an organic compound having a function of transporting electrons is preferably used. In addition, an organic compound capable of serving as an electron acceptor for the metal is preferably used.

[0071] Furthermore, since the organic compound used in one embodiment of the present invention interacts with the metal in a tridentate or tetradentate manner, its metal interaction function is very high. Therefore, in addition to transition metals from Groups 3 to 11, metals from Groups 12 or 13 with closed-shell d orbitals can also be used in one embodiment of the present invention. Furthermore, metals such as gold (Au) and cobalt (Co) with very large work functions can be used.

[0072] Since metals with large work functions, such as metals belonging to Groups 3 to 13, have low reactivity with water and oxygen, when they are used in light-emitting elements, there is less concern about element degradation due to water and oxygen when using metals with small work functions. 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 even 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 with excellent moisture resistance and oxygen resistance.

[0073] Figure 1B A schematic diagram illustrating an electron injection layer 130 in a light-emitting element according to 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 in a tridentate or tetradentate manner.

[0074] Figure 1C The energy diagram of the electron injection layer 130 in the light-emitting element of one embodiment of the present invention is shown. When the metal 132 and the compound 131 are mixed, the atoms of the compound 131 and the metal 132 interact with each other, thereby forming a SOMO. At this time, the HOMO (Highest Occupied Molecular Orbital) energy level formed by the interaction between the atoms of the compound 131 and the metal 132 is preferably the same as the HOMO energy level of the original compound 131. When an organic compound having the 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, holes are not easily transferred from the electron injection layer 130 to the electrode 102, and the carrier balance in the light-emitting element can be improved, which is preferred. Note that in this specification and the like, HOMO refers to the highest energy molecular orbital occupied by electrons.

[0075] Since SOMO is an orbital with only one electron, when a voltage is applied to the light-emitting element 150, the electrons in SOMO become carriers in the light-emitting element and are transported 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 through the electron transport layer 118 into the light-emitting layer 140. In other words, since the electron injection layer 130 has a material that forms a combination of SOMO, 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 compound 131. Therefore, the LUMO energy level of compound 131 is preferably higher. Specifically, the LUMO energy level of compound 131 is preferably greater than -3.6 eV and less than -2.3 eV. 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 lowering the electron injection barrier from the electrode 102 to the light-emitting layer 140 .

[0076] The HOMO and LUMO levels of organic compounds are generally estimated using CV (cyclic voltammetry), photoelectron spectroscopy, optical absorption spectroscopy, inverse photoelectron spectroscopy, etc. When comparing values ​​between different compounds, it is preferred to use values ​​estimated by the same measurement.

[0077] Here, the metal preferably belongs to any of Groups 3, 5, 7, 9, 11, and 13. Metals from these odd-numbered groups have one electron (unpaired electron) in the outermost orbital and therefore easily form a SOMO with compound 131, making them particularly preferred.

[0078] <Estimation of the SOMO energy level of the interaction between metal 132 and compound 131 by quantum chemical calculation> In a light-emitting element of one embodiment of the present invention, compound 131 and metal 132 form a SOMO, but when the SOMO energy level is significantly low, it is not suitable for an 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 metals at the 3-dentate or 4-dentate level, 4', 4""-(1,4-phenylene)bis(2,2':6',2"-terpyridine) (abbreviated as: tPy2P), 4', 4""-(9,10-anthryl)bis(2,2':6',2"-terpyridine) (abbreviated as: tPy2A), 2,2'-(pyridine-2,6-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviated as: The following are the abbreviations: 2,6(P-Bqn)2Py), 2,2'-(2,2'-bipyridine-6,6'-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviated as 6,6'(P-Bqn)2BPy), 2,4,6-tris(2-pyridyl)-1,3,5-triazine (abbreviated as 2Py3Tzn) and 2,4,6-tris(5-phenylpyrimidin-2-yl)-1,3,5-triazine (abbreviated as PPm3Tzn).

[0079] [Chemical Formula 8]

[0080] [Table 1]

[0081] The LUMO levels of the organic compounds listed in Table 1 were calculated by cyclic voltammetry (CV).

[0082] As a measuring apparatus, an electrochemical analyzer (ALS model 600A or 600C manufactured by BAS Inc.) was used. The solution for CV measurement was prepared as follows: as a solvent, dehydrated dimethylformamide (DMF) (manufactured by Aldrich Co., Ltd., 99.8%, catalog number: 22705-6) was used, tetra-n-butylammonium perchlorate (n-Bu4NClO4) (manufactured by Tokyo Chemical Industry Co., Ltd., catalog number: T0836) was dissolved at a concentration of 100 mmol / L as a supporting electrolyte, and the measurement object was dissolved at a concentration of 2 mmol / L. In addition, a platinum electrode (manufactured by BAS Inc., PTE platinum electrode) was used as a working electrode, a platinum electrode (manufactured by BAS Inc., Pt counter electrode for VC-3 (5 cm)) was used as an auxiliary electrode, and an Ag / Ag was used as a reference electrode. +Electrode (manufactured by BAS Inc., RE7 non-aqueous solvent type reference electrode). In addition, the measurement was carried out at room temperature (above 20°C and below 25°C). The scanning speed during CV measurement was unified to 0.1V / 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 wave, and Ec is the intermediate potential between the reduction-oxidation wave. Here, it is known that the potential energy of the reference electrode used in this embodiment relative to the vacuum energy level is -4.94[eV], so the HOMO energy level [eV] = -4.94-Ea, LUMO energy level [eV] = -4.94-Ec are used to calculate the HOMO energy level and the LUMO energy level, respectively.

[0083] As a quantum chemical calculation program, Gaussian09 is used. A high-performance computer (manufactured by SGI Corporation, ICE X) is used for calculation. First, the most stable structure of the ground state of the organic compound, the ground state of the metal, and the ground state of the composite material of the organic compound and the metal is calculated using density functional theory (DFT). 6-311G (d, p) and LanL2DZ are used as basis functions. B3LYP is used as a functional. Next, the stability energy is calculated by subtracting the sum of the total energy of the organic compound and the total energy of the metal from the total energy of the composite material of the organic compound and the metal. In other words, (stability energy) = (total energy of the composite material of the organic compound and the metal) - (total energy of the organic compound) - (total energy of the metal). All the energies of DFT are represented by the sum of potential energy, electrostatic energy between electrons, kinetic energy of electrons, and exchange correlation energy including all complex interactions between electrons. In DFT, since the exchange correlation effect is approximated using the functional (function of function) of the single electron potential represented by electron density, the calculation accuracy is high.

[0084] Table 1 shows the results of calculating the SOMO energy levels formed by each organic compound and each metal for manganese (Mn) of the 7th group transition metal, cobalt (Co) of the 9th group transition metal, copper (Cu), silver (Ag) and gold (Au) of the 11th group transition metal, and aluminum (Al) and indium (In) of the 13th group metal. In addition, the SOMO energy levels formed by lithium (Li), which is widely used as an electron injection layer material, and each organic compound are also calculated. The following results were obtained by calculation: the organic compound and metal combinations shown in Table 1 all interact and stabilize the organic compound near the nitrogen in the heteroaromatic ring included in the organic compound, and the stabilization energy is a negative value. That is, when these organic compounds are mixed with metals, the energy in the case of the organic compound interacting with the metal is more stable than when the organic compound does not interact with the metal. In this way, a stable composite material can be obtained by interacting with the metal in a tridentate or quadridentate manner. In addition, as shown in Table 1, the SOMO energy level formed by the organic compound having the function of interacting with the metal at 3 teeth or 4 teeth and each metal and the SOMO energy level formed by each organic compound and Li are roughly equal. It can be seen that the composite material of the organic compound having the function of interacting with the metal at 3 teeth or 4 teeth and the metal has high electron injection. In particular, a composite material of Cu, Ag, Au of a Group 11 element or Co of a Group 9 element shows a high SOMO energy level, from which it can be seen that the composite material of the organic compound having the function of interacting with the metal at 3 teeth or 4 teeth and the metal belonging to Group 9 or Group 11 has high electron injection characteristics.

[0085] In addition, as can be seen from Table 1, the SOMO energy level formed by the organic compound having a function of interacting with the metal in the tridentate or tetradentate and each metal is more easily affected by the LUMO energy level of the organic compound than the work function of each metal. Therefore, by using an organic compound with a high LUMO energy level, a composite material of an organic compound and a metal having high SOMO energy level and electron injection characteristics can be manufactured. As described above, the LUMO energy level of the organic compound is preferably greater than -3.6 eV and less than -2.3 eV.

[0086] On the other hand, when considering the manufacturing process of the light-emitting element, in general, the EL layer of the light-emitting element, especially the electron injection layer and the cathode, is formed by vacuum evaporation. In this case, it is preferred to use a material that can be easily vacuum-deposited, that is, a material with a low melting point, boiling point or sublimation point, and it is preferred to use a material whose vapor pressure is low during vacuum evaporation. Here, the melting point of the 11th group element or the 13th group element is lower than that of the 7th group element or the 9th group element, so the 11th group element or the 13th group element is suitable for vacuum evaporation. In particular, the 11th group element or the 13th group element such as Ag or Al has a low melting point, so by using the vacuum evaporation method, the metal atoms and the organic compound can be easily mixed, so it is preferred.

[0087] Ag, Cu, Au, Al, and In can also be used as cathode materials. By using the same material as the electron injection layer 130 and the electrode 102, the light-emitting element can be manufactured simply, so it is preferred. In addition, by using the same material as the electron injection layer 130 and the electrode 102, the adhesion between the electron injection layer 130 and the electrode 102 can be improved, thereby improving the reliability of the light-emitting element. In addition, the manufacturing cost of the light-emitting element can be reduced.

[0088] Furthermore, in the light-emitting element of one embodiment of the present invention, a metal having a large work function can be used for the electron injection layer 130. Therefore, a metal having a work function greater than or equal to the work function of the metal included in the electrode 102 can be used for the electron injection layer 130. In the light-emitting element of one embodiment of the present invention, even when a metal having a large work function is used, the electron injection barrier between the electrode 102 and the electron injection layer 130 can be lowered, thereby reducing the driving voltage.

[0089] 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 multiple electron-deficient heteroaromatic rings. When adopting this structure, since compound 131 easily accepts electrons, it is easy to form a SOMO when interacting with the atoms of metal 132. In addition, since the electron transport properties of the compound having the electron-deficient heteroaromatic ring are excellent, when used in the electron injection layer, the driving voltage of the light-emitting element can be reduced. Therefore, as compound 131, a compound having an electron-deficient heteroaromatic ring is preferably used.

[0090] 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, pyrazine ring, 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.

[0091] When an organic compound is used as compound 131, the number of carbon atoms is preferably 25 to 100. This number of carbon atoms allows for an organic compound with good sublimation properties, thereby suppressing thermal decomposition of the organic compound during vacuum deposition, resulting in good material utilization efficiency. Furthermore, the glass transition point (Tg) is preferably 100°C or higher. By using an organic compound with this Tg for the EL layer, a light-emitting element with excellent heat resistance can be realized.

[0092] Note that in the organic compounds used in this calculation, the nitrogen atoms acting as coordinating atoms are present on heterocyclic rings and have conjugated double bonds 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 and metal 132 interact to form a ring structure). Combinations of compound 131 and metal 132 that can form a chelate ring are preferred because they easily interact to form a SOMO.

[0093] Therefore, the organic compound having a tridentate or tetradentate function of interacting with a metal 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).

[0094] [Chemical Formula 9]

[0095] In the general formula (G0), A 1 、A 2 and A 3 Each independently represents a substituted or unsubstituted heteroaromatic ring having 1 to 30 carbon atoms, A 1 、A 2 and A 3 They may also form a condensed ring.

[0096] The organic compound represented by the general formula (G0) has a conjugated double bond in which the nitrogen atoms of the heteroaromatic ring are arranged in the order of NCCN and has a tridentate or higher metal interaction function. As described above, an organic compound having such a structure readily forms a SOMO when mixed with a metal, and such an organic compound can be suitably used in a light-emitting element according to one embodiment of the present invention.

[0097] In the above general formula (G0), as A 1 、A 2 and A 3The substituted or unsubstituted heteroaromatic ring having 1 to 30 carbon atoms may be exemplified by 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, the heteroaromatic rings represented by (A-1) to (A-16) below may be cited. Note that the heteroaromatic rings represented by A-1 are substituted or unsubstituted heteroaromatic rings having 1 to 30 carbon atoms. 1 、A 2 and A 3 The substituted or unsubstituted heteroaromatic ring having 1 to 30 carbon atoms is not limited thereto. 1 、A 2 and A 3 They can also form fused rings with each other. For example, A 1 With A 2 They may be bonded to each other to form a phenanthroline ring.

[0098] [Chemical Formula 10]

[0099] Furthermore, an organic compound having a tridentate or tetradentate function of interacting with a metal 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 (G1).

[0100] [Chemical Formula 11]

[0101] In the general formula (G1), X 1 To X 6 Each independently represents carbon (C) or nitrogen (N), wherein 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 aromatic hydrocarbon group having 6 to 25 carbon atoms, or a substituted or unsubstituted heteroaromatic hydrocarbon group having 3 to 30 carbon atoms, and 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 aromatic hydrocarbon group having 6 to 25 carbon atoms, or a substituted or unsubstituted heteroaromatic hydrocarbon group having 3 to 30 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 aromatic hydrocarbon group having 6 to 60 carbon atoms, or a heteroaromatic hydrocarbon group having 2 to 60 carbon atoms.

[0102] An organic compound having a tridentate or tetradentate metal interaction function, such as an 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. Due to the excellent electrochemical stability of these rings, a highly reliable light-emitting element can be provided. In addition, due to the excellent electron transport properties, a light-emitting element with a reduced driving voltage can be provided.

[0103] Furthermore, an organic compound having a tridentate or tetradentate function of interacting with a metal 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 (G2).

[0104] [Chemical Formula 12]

[0105] In the general formula (G2), X 1 and X 2 Each independently represents carbon (C) or nitrogen (N), wherein 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 aromatic hydrocarbon group having 6 to 25 carbon atoms, or a substituted or unsubstituted heteroaromatic hydrocarbon group having 3 to 30 carbon atoms, and 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 aromatic hydrocarbon group having 6 to 25 carbon atoms, or a substituted or unsubstituted heteroaromatic hydrocarbon group having 3 to 30 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 aromatic hydrocarbon group having 6 to 60 carbon atoms, or a heteroaromatic hydrocarbon group having 3 to 60 carbon atoms.

[0106] Organic compounds with a pyridine skeleton tend to have high LUMO energy levels. Therefore, when an organic compound with a pyridine skeleton represented by general formula (G2) is mixed with a metal, a composite material with a high SOMO energy level can be produced. In other words, by mixing an organic compound containing a pyridine ring and having a tridentate or tetradentate interaction with a metal with a metal, a composite material with high electron injection properties can be produced.

[0107] Furthermore, an organic compound having a tridentate or tetradentate function of interacting with a metal that can be suitably used in the light-emitting element of one embodiment of the present invention is represented by any one of the following general formulas (G3-1) to (G3-3).

[0108] [Chemical Formula 13]

[0109] 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 aromatic hydrocarbon group having 6 to 25 carbon atoms, or a substituted or unsubstituted heteroaromatic hydrocarbon group having 3 to 30 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 aromatic hydrocarbon group having 6 to 60 carbon atoms, or a heteroaromatic hydrocarbon group having 2 to 60 carbon atoms.

[0110] In addition, 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 is represented by the following general formulas (G4-1) to (G4- 3) is any one of the representations.

[0111] [Chemical Formula 14]

[0112] 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 aromatic hydrocarbon group having 2 to 60 carbon atoms, or a heteroaromatic hydrocarbon group having 2 to 60 carbon atoms.

[0113] <Examples of Substituents> In the general formulae (G0) to (G3), as R 1 to R 8 The substituent represented by or included in C may include 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 aromatic hydrocarbon group having 6 to 25 carbon atoms, or a substituted or unsubstituted heteroaromatic hydrocarbon group having 3 to 30 carbon atoms. Specifically, for example, the above-mentioned alkyl group may include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, n-hexyl, etc.; for example, the above-mentioned cycloalkyl group may include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, etc.; and for example, the above-mentioned aryl group may include phenyl, naphthyl, biphenyl, fluorenyl, spirofluorenyl, etc. More specifically, for example, the groups represented by the following structural formulas (R-1) to (R-56) may be mentioned. Note that the group represented by R 1 to R 8 The substituents represented by or included in C are not limited thereto.

[0114] [Chemical Formula 15]

[0115] In addition, in the general formulae (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 aromatic hydrocarbon group having 6 or more and 60 or less carbon atoms, or a heteroaromatic hydrocarbon group having 3 or more and 60 or less carbon atoms. As the above-mentioned alkyl group, specifically, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a n-hexyl group, etc. can be mentioned; as the above-mentioned cycloalkyl group, for example, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc. can be mentioned; as the above-mentioned aryl group, a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, a spirofluorenyl group, etc. can be mentioned. More specifically, for example, groups represented by the following structural formulae (Ar-1) to (Ar-48) can be mentioned. Note that the group represented by Ar is not limited thereto and may also have a substituent.

[0116] [Chemical Formula 16]

[0117] <Specific Examples of Compounds> Specific structures of the compounds represented by general formulae (G0) to (G3) include organic compounds represented by the following structural formulae (100) to (111) and structural formulae (200) to (211). Note that the organic compounds represented by general formulae (G0) to (G3) are not limited to the following examples.

[0118] [Chemical Formula 17]

[0119] [Chemical Formula 18]

[0120] 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 further preferably 0.2 or more and 0.8 or less. By mixing metal 132 and compound 131 in this ratio, a light-emitting element with excellent electron injection properties can be provided. When the molar ratio of metal 132 to compound 131 is too low compared to the above ratio, the amount of compound 131 that interacts with metal 132 to form SOMO is small, which sometimes leads to a decrease in electron injection properties. In addition, when the molar ratio of metal 132 to compound 131 is too high compared to the above ratio, the transmittance of the electron injection layer 130 is reduced, which sometimes leads to a decrease in the luminous efficiency of the light-emitting element.

[0121] The LUMO energy level of the organic compound included in the electron transport layer 118 is preferably lower than the SOMO energy level formed in the electron injection layer 130. This structure can reduce the electron injection barrier between the electron injection layer 130 and the electron transport layer 118, thereby reducing the driving voltage. In addition, since the organic compound included in the electron transport layer 118 is required to have electron transport properties, it preferably includes an electron-deficient heteroaromatic ring.

[0122] The thickness of the electron injection layer 130 is preferably 3 nm or greater, more preferably 5 nm or greater. This structure facilitates the composite material mixed with the metal 132 and the compound 131 to function better. In addition, the thickness of the electron injection layer 130 is preferably 50 nm or less, more preferably 20 nm or less, and even more preferably 10 nm or less. This structure can reduce light absorption by the electron injection layer 130 and provide a light-emitting element with high luminous efficiency.

[0123] <Structural Example 2 of Light-Emitting Element> Below, refer to Figure 2A An example of a structure different from that of the light-emitting element 150 shown in FIG. 1 will be described.

[0124] Figure 2A : is a schematic cross-sectional view showing a light emitting device according to one embodiment of the present invention. Figure 2A 1 , the same hatching may be used to indicate a portion having the same function as the reference numerals shown in FIG1 , and the reference numerals thereof may be omitted. In addition, the same reference numerals may be used to indicate a portion having the same function, and detailed description thereof may be omitted.

[0125] 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 also includes a buffer layer 127. The buffer layer 127 is provided between the electron injection layer 130 and the electrode 102.

[0126] 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 .

[0127] In one embodiment of the present invention, the electron injection layer 130 uses a composite material of the compound 131 and the metal 132, and the buffer layer 127 uses a compound 133 having an electron-deficient heteroaromatic ring. Electron-deficient heteroaromatic rings have excellent electron transport properties, thereby reducing the driving voltage of the light-emitting element.

[0128] The buffer layer 127 is preferably sandwiched between the electron injection layer 130 and the electrode 102 because it can reduce the electron injection barrier between the electrode 102 and the electron injection layer 130. The thickness of the buffer layer 127 is preferably not less than 1 nm and not more than 20 nm. By adopting this structure, the electron injection barrier can be reduced while maintaining high electron transport properties.

[0129] The LUMO energy level of the compound 133 is preferably lower than the SOMO energy level formed in the electron injection layer 130. This structure is preferred because it can reduce the electron injection barrier between the electron injection layer 130 and the electrode 102.

[0130] <Structural Example 3 of Light-Emitting Element> Below, refer to Figure 2B To Figure 1A The light emitting element 150 and Figure 2A Different structural examples of the light emitting element 152 are described below.

[0131] Figure 2B : is a schematic cross-sectional view showing a light emitting element according to one embodiment of the present invention. Figure 2B 1 , the same hatching may be used to indicate a portion having the same function as the reference numerals shown in FIG1 , and the reference numerals thereof may be omitted. In addition, the same reference numerals may be used to indicate a portion having the same function, and detailed description thereof may be omitted.

[0132] Light-emitting element 154 includes a pair of electrodes (electrode 101 and electrode 102) and an EL layer 100 between the pair of electrodes. EL layer 100 includes at least a light-emitting layer 140 and an electron injection layer 130. EL layer 100 also includes a charge generation layer 129. Charge generation layer 129 is provided between electron injection layer 130 and electrode 102.

[0133] Figure 2B 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 .

[0134] like Figure 2B As shown, by providing the charge generation layer 129 between the electrode 102 and the electron injection layer 130, the probability of the electron injection layer 130 coming into contact with oxygen or moisture can be reduced, thereby further improving the moisture resistance and oxidation resistance of the light-emitting element.

[0135] The charge generation layer 129 may have either 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. A stack of these two structures is also possible, but the structure in which an electron-accepting material is added to a hole-transporting material is preferred because it has high moisture resistance and requires fewer layers.

[0136] As described above, when the charge generation layer 129 comprises a hole transport 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 injection layer 130, the electron accepting material of the charge generation layer 129 extracts electrons from the material used for the electron injection layer 130, thereby forming a depletion layer near the interface between the charge generation layer 129 and the electron injection layer 130. Therefore, the driving voltage may increase. In order to prevent the formation of this depletion layer, it is necessary to provide a layer having the function of transporting electrons between the electron injection layer 130 and the charge generation layer 129.

[0137] On the other hand, in a light-emitting element of one embodiment of the present invention, by making the electron injection layer 130 include a composite material of a transition metal and an organic compound having a function of interacting with the metal at a tridentate or quadrudentate, a charge generation layer 129 can be provided without forming the above-mentioned depletion layer, thereby making it possible to manufacture a light-emitting element with a small number of layers and a low driving voltage.

[0138] The thickness of charge generation layer 129 is not particularly limited and can be adjusted appropriately. For example, by adjusting the thickness from light-emitting layer 140 to electrode 102, light emitted from light-emitting layer 140 can be efficiently extracted outside the light-emitting element. In other words, by adjusting the thickness of charge generation layer 129, light extraction efficiency can be improved.

[0139] The charge generation layer 129 and the electrode 102 are preferably arranged in contact with each other. This structure can reduce the electron injection barrier between the electrode 102 and the EL layer 100, thereby reducing the driving voltage of the light-emitting element. Furthermore, it is more preferable that the charge generation layer 129 is in contact with the electron injection layer 130. In one embodiment of the present invention, a light-emitting element with a low driving voltage can be manufactured even if the charge generation layer 129 and the electron injection layer 130 are in contact with each other. Therefore, by adopting this structure, the number of EL layers 100 stacked can be reduced.

[0140] Transition metal oxides are suitable for the electron-accepting material contained in the charge generation layer 129. Examples of the transition metal oxide include titanium oxide, vanadium oxide, tantalum oxide, molybdenum oxide, tungsten oxide, rhenium oxide, ruthenium oxide, chromium oxide, zirconium oxide, hafnium oxide, and silver oxide. 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 embodiment 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-mentioned compounds.

[0141] As the hole-transporting material included 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. Organic compounds containing such skeletons have high hole-transporting properties, so using such organic compounds in the charge generation layer 129 can reduce the driving voltage of the light-emitting element. The hole-transporting material included in the charge generation layer 129 is not limited to the compounds listed above.

[0142] The composite material of the metal 132 and the compound 131 having a tridentate or quadridentate interaction with the metal can be used in thin-film solar cells. More specifically, the composite material is also suitable for the electron injection layer of a thin-film solar cell.

[0143] <Components of Light-Emitting Element> Next, the components of the light-emitting element shown in FIG. 1 and FIG. 2 will be described in detail.

[0144] Electron injection layer The electron injection layer 130 is a layer containing a substance with high electron injection properties, and the composite materials of the above-mentioned metal and the organic compound having the function of interacting with the metal at the 3-dentate or 4-dentate level are suitable for use in these layers. As the organic compound having the function of interacting with the metal at the 3-dentate or 4-dentate level, organic compounds represented by general formulas (G0) to (G4-3) can be used, and specifically organic compounds represented by structural formulas (100) to (111) and structural formulas (200) to (211) can be used. Heterocyclic compounds having a diazine (pyrimidine or pyrazine) skeleton and a triazine skeleton have high electron transport properties and also help to reduce the driving voltage, so they are particularly preferred. In addition, the metal and the organic compound having the function of interacting with the metal at the 3-dentate or 4-dentate level preferably have a ratio of 1×10 -6 cm 2 In addition, a substance other than the above substances may be used for the electron injection layer 130 as long as the electron-transporting property is higher than the hole-transporting property.

[0145] Hole injection layer The hole injection layer 111 and the charge generation layer 129 have the function of lowering the injection barrier of holes from one of the pair of electrodes (electrode 101 or electrode 102) to promote hole injection, and can be formed using, for example, transition metal oxides, phthalocyanine derivatives or aromatic amines. Examples of transition metal oxides include molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, manganese oxide, etc. Examples of phthalocyanine derivatives include phthalocyanine or metal phthalocyanine. Examples of aromatic amines include benzidine derivatives or phenylenediamine derivatives. In addition, polymer derivatives such as polythiophene or polyaniline can also be used, typically poly(ethylenedioxythiophene) / poly(styrenesulfonic acid) as self-doped polythiophene.

[0146] The hole injection layer 111 and the charge generation layer 129 may also comprise a composite material of a hole transport material and a material that exhibits electron-accepting properties for the hole transport material. Alternatively, a stack of a layer comprising a material exhibiting electron-accepting properties and a layer comprising a hole transport material may be used. In a steady state or in the presence of an electric field, charge transfer can be performed between these materials. Examples of materials exhibiting electron-accepting properties include organic acceptors such as quinone dimethane derivatives, tetrachlorobenzoquinone derivatives, and hexaazatriphenylene derivatives. Specific examples include compounds having an electron-withdrawing group (particularly a halogen group such as a fluorine group or a cyano group), such as 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviated as F4-TCNQ), chloranil, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviated as HAT-CN), and 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviated as F6-TCNNQ). Compounds in which an electron-withdrawing group is bonded to a fused aromatic ring having multiple heteroatoms, such as HAT-CN, are particularly preferred because they are thermally stable. In addition, [3]radialene derivatives containing electron-withdrawing groups (especially halogen groups such as fluorine groups and cyano groups) are particularly preferred because of their very high electron-accepting properties. Specifically, they include: α,α',α"-1,2,3-cycloalkyltriene tris[4-cyano-2,3,5,6-tetrafluorophenylacetonitrile], α,α',α"-1,2,3-cyclopropanetriene tris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl) )phenylacetonitrile], α,α',α"-1,2,3-cycloalkanetriylidenetris[2,3,4,5,6-pentafluorophenylacetonitrile], and the like. In addition, transition metal oxides, such as oxides of Group 4 to Group 8 metals, can also be used. Specifically, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, rhenium oxide, and the like can be used. Molybdenum oxide is particularly preferably used because it is stable even in the atmosphere, has low hygroscopicity, and is easy to handle.

[0147] As the hole transport material, a material having a hole transport property higher than an electron transport property can be used, and preferably a material having a 1×10 -6 cm 2 A material with a hole mobility of 1000 nm / Vs or higher can be used. Specifically, aromatic amines, carbazole derivatives, aromatic hydrocarbons, stilbene derivatives, and the like, which are listed as hole-transporting materials for the light-emitting layer 140, can be used. Preferably, the material has a heteroaromatic skeleton with 1 to 20 carbon atoms. Particularly preferably, the material has a nitrogen-containing five-membered heteroaromatic ring skeleton. The hole-transporting material can also be a polymer compound.

[0148] In addition, as hole transport materials, aromatic hydrocarbons can also be mentioned, for example, 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviated as t-BuDNA), 2-tert-butyl-9,10-di(1-naphthyl)anthracene, 9,10-bis(3,5-diphenylphenyl)anthracene (abbreviated as DPPA), 2-tert-butyl-9,10-bis(4-phenylphenyl)anthracene (abbreviated as t-BuDBA), 9,10-di(2-naphthyl)anthracene (abbreviated as DNA), 9,10-diphenylanthracene (abbreviated as DPAnth), 2-tert-butylanthracene (abbreviated as t-BuAnth), 9,10-bis(4-methyl-1-naphthyl)anthracene (abbreviated as DP MNA), 2-tert-butyl-9,10-bis[2-(1-naphthyl)phenyl]anthracene, 9,10-bis[2-(1-naphthyl)phenyl]anthracene, 2,3,6,7-tetramethyl-9,10-di(1-naphthyl)anthracene, 2,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene, 9,9'-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, perylene, 2,5,8,11-tetra(tert-butyl)perylene, etc. In addition, pentacene, coronene, etc. can also be used. Thus, it is more preferable to use a 1×10 -6 cm 2 Aromatic hydrocarbons having a hole mobility of 1 / Vs or higher and 14 to 42 carbon atoms.

[0149] In addition, the aromatic hydrocarbon may have a vinyl skeleton. As the aromatic hydrocarbon having a vinyl group, for example, Examples thereof include 4,4'-bis(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi), 9,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene (abbreviation: DPVPA), and the like.

[0150] In addition, 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-[ Thiophene compounds such as [4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviated as DBTFLP-IV) and [4-[3-(triphenylene-2-yl)phenyl]dibenzothiophene (abbreviated as mDBTPTp-II), furan compounds, fluorene compounds, triphenylene compounds, and phenanthrene compounds are also used. Among these, compounds with pyrrole, furan, thiophene, and aromatic amine skeletons are preferred due to their stability and reliability. Compounds with these skeletons have high hole transport properties and also contribute to lowering the driving voltage.

[0151] Hole Transport Layer The hole-transport layer 112 is a layer containing a hole-transporting material, and the materials exemplified as the material 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 .

[0152] In addition, it is preferred to use a hole transport 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 can also be a stack of two or more layers. In this case, it is preferred to stack the hole transport material in such a manner that the HOMO energy level decreases from the hole injection layer 111 side to the light-emitting layer 140 side. When the hole transport layer 112 has two or more layers, in order to smoothly transport holes, the difference in the HOMO energy level of each hole transport material 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.

[0153] Examples of materials having hole transport properties include 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviated as NPB), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviated as TPD), 4,4'-bis[N-(spiro-9,9'-difluoren-2-yl)-N-phenylamino]biphenyl (abbreviated as BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviated as BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviated as mBPAFLP), 4-phenyl- 4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (PCBA1BP), 4,4'-diphenyl-4"-(9-phenyl-9H-carbazol-3-yl)triphenylamine (PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (PCBANB), 4,4'-di(1-naphthyl)-4"-(9-phenyl-9H-carbazol-3-yl)triphenylamine (PCBNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (PCBAF) , N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]spiro-9,9'-difluoren-2-amine (abbreviated as: PCBASF) and other compounds having an aromatic amine skeleton; 1,3-bis(N-carbazolyl)benzene (abbreviated as: mCP), 4,4'-bis(N-carbazolyl)biphenyl (abbreviated as: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviated as: CzTP), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviated as: PCCP) and other compounds having a carbazole skeleton; 4,4',4"-(benzene-1,3,5-triyl)tris(dibenzothiophene) (abbreviated as: DBT3P -II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviated as DBTFLP-III), 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviated as DBTFLP-IV), and compounds having a furan skeleton such as 4,4',4"-(benzene-1,3,5-triyl)tris(dibenzofuran) (abbreviated as DBF3P-II), 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviated as mmDBFFLBi-II). Among them, compounds having an aromatic amine skeleton and compounds having a carbazole skeleton are preferred because they have high reliability and high hole transport properties and also contribute to reducing the driving voltage. In addition, in addition to the above-mentioned hole transport materials, hole transport materials can also be selected from various substances for use.

[0154] Furthermore, examples of substances with high hole-transport properties include 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviated as PCPN), 3-[4-(9-phenanthrenyl)-phenyl]-9-phenyl-9H-carbazole (abbreviated as PCPPn), 4-phenyl-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviated as PCBA1BP), 4,4'-di(1-naphthyl)-4"-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviated as PCBNBB), 4-phenyldiphenyl-(9-phenyl-9H-carbazole-3-yl)amine (abbreviated as PCA1BP), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviated as PCPBN), and 4-phenyl-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviated as PCBA1BP). CCP), N-[4-(9H-carbazol-9-yl)phenyl]-N-(4-phenyl)phenylaniline (abbreviated as: YGA1BP), 1,3,5-tris(dibenzothiophen-4-yl)-benzene (abbreviated as: DBT3P-II), 4,4',4"-(benzene-1,3,5-triyl)tris(dibenzofuran) (abbreviated as: DBF3P-II), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviated as: BPAFLP), 4-[3-(triphenylene-2-yl)phenyl]dibenzothiophene (abbreviated as: mDBTPTp-II), 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviated as: NPB or α-NPD), N,N' compounds having an aromatic amine skeleton, such as 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'-difluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 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'-di(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 here mainly have a hole mobility of 1×10 -6 cm2 However, any substance other than these may be used as long as it has a higher hole-transporting property than an electron-transporting property.

[0155] Furthermore, these compounds that can be used in the hole transport layer can also be used in the hole injection layer. In addition, they can also be suitably used as hole transport materials in the charge generation layer 129 .

[0156] Luminous Layer The light-emitting layer 140 includes a light-emitting material capable of emitting at least one of violet, blue, cyan, green, yellow-green, yellow, orange, and red light. Furthermore, the light-emitting layer 140 includes an electron-transporting material and / or a hole-transporting material as a host material in addition to the light-emitting material.

[0157] As the light-emitting material, a light-emitting substance that converts singlet excited state energy into light-emitting substance or a light-emitting substance that converts triplet excited state energy into light-emitting substance can be used. Examples of the light-emitting substance include the following materials.

[0158] As a luminescent substance that converts singlet excitation energy into luminescence, for example, a substance that emits fluorescence (fluorescent compound) can be cited. There is no particular limitation on the fluorescent compound, but anthracene derivatives, tetracene derivatives, Examples of the chrysene derivative, phenanthrene derivative, pyrene derivative, perylene derivative, stilbene derivative, acridone derivative, coumarin derivative, phenoxazine derivative, and phenothiazine derivative include the following.

[0159] Specifically, examples of the material include 5,6-bis[4-(10-phenyl-9-anthracenyl)phenyl]-2,2'-bipyridine (abbreviated as PAP2BPy), 5,6-bis[4'-(10-phenyl-9-anthracenyl)biphenyl-4-yl]-2,2'-bipyridine (abbreviated as PAPP2BPy), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluorene-9-yl)phenyl]pyrene-1,6-diamine (abbreviated as 1,6FLPAPrn), N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluorene-9 -yl)phenyl]pyrene-1,6-diamine (abbreviated as: 1,6mMemFLPAPrn), N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-N,N'-bis(4-tert-butylphenyl)pyrene-1,6-diamine (abbreviated as: 1,6tBu-FLPAPrn), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-3,8-dicyclohexylpyrene-1,6-diamine (abbreviated as: ch-1,6FLPAPrn), N,N'-(pyrene-1,6-diyl)bis[(6,N-diphenylbenzo[b]naphtho)pyrene-1,6-diamine [1,2-d]furan)-8-amine] (abbreviated as 1,6BnfAPrn-03), N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviated as YGA2S), 4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviated as YGAPA), 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviated as 2YGAPPA), N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviated as PCAPA), perylene, 2,5,8,11-tetra(tert-butyl)perylene (abbreviated as TBP), 4 -(10-phenyl-9-anthryl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), N,N"-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene)bis[N,N',N'-triphenyl-1,4-phenylenediamine] (abbreviation: DPABPA), N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), N,N,N',N',N",N",N"',N"'-octaphenyldibenzo[g,p] -2,7,10,15-tetramine (abbreviated as DBC1), coumarin 30, N-(9,10-diphenyl-2-anthracenyl)-N,9-diphenyl-9H-carbazole-3-amine (abbreviated as 2PCAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthracenyl]-N,9-diphenyl-9H-carbazole-3-amine (abbreviated as 2PCABPhA), N-(9,10-diphenyl-2-anthracenyl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviated as 2DPAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthracenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviated as 2DPAB PhA), 9,10-bis(1,1'-biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracen-2-amine (abbreviated as 2YGABPhA), N,N,9-triphenylanthracen-9-amine (abbreviated as DPhAPhA), Coumarin 6, Coumarin 545T, N,N'-diphenylquinacridone (abbreviated as DPQd), rubrene, 2,8-di-tert-butyl-5,11-bis(4-tert-butylphenyl)-6,12-diphenylnaphthacene (abbreviated as TBRb), Nile Red, 5,12-bis(1,1'-biphenyl-4-yl)-6,11-diphenylnaphthacene (abbreviated as BPT), 2-(2-{2-[4-(dimethylamino)phenyl]-1,2-diphenylnaphthacene] ]vinyl}-6-methyl-4H-pyran-4-ylidene)malononitrile (abbreviated as DCM1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)vinyl]-4H-pyran-4-ylidene}malononitrile (abbreviated as DCM2), N,N,N',N'-tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviated as p-mPhTD), 7,14-diphenyl-N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviated as 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}malononitrile (abbreviated as 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}malononitrile (abbreviated as DCJTB), 2-(2,6-bis{2-[4-(dimethylamino)phenyl]vinyl}-4H-pyran-4-ylidene)malononitrile (abbreviated as BisDCM), 2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)vinyl]-4H-pyran-4-ylidene}malononitrile (abbreviated as: BisDCJTM), 5,10,15,20-tetraphenylbisbenzo[5,6]indeno[1,2,3-cd:1',2',3'-lm]perylene, etc.

[0160] As luminescent substances that convert triplet excitation energy into luminescence, for example, substances that emit phosphorescence (phosphorescent compounds) can be mentioned. In addition, as phosphorescent compounds, iridium, rhodium, platinum-type organometallic complexes or metal complexes can be mentioned. In addition, platinum complexes or organic iridium complexes with porphyrin ligands can be mentioned, wherein organic iridium complexes are particularly preferably used, for example, iridium-type ortho-metal complexes. As ortho-metallated ligands, 4H-triazole ligands, 1H-triazole ligands, imidazole ligands, pyridine ligands, pyrimidine ligands, pyrazine ligands or isoquinoline ligands can be mentioned. At this time, the phosphorescent compound has an absorption band of triple MLCT (Metal to Ligand Charge Transfer: charge transfer from metal to ligand) transition.

[0161] Examples of substances having a light emission peak in the blue or green wavelength region include tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN2]phenyl-κC}iridium(III) (abbreviated as Ir(mpptz-dmp)3), tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazole)iridium(III) (abbreviated as Ir( Mptz)3), tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazole]iridium(III) (abbreviated as Ir(iPrptz-3b)3), tris[3-(5-biphenyl)-5-isopropyl-4-phenyl-4H-1,2,4-triazole]iridium(III) (abbreviated as Ir(iPr5btz)3), etc. having a 4H-triazole skeleton; tris[3-methyl -1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazole]iridium(III) (abbreviated as: Ir(Mptz1-mp)3), tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazole)iridium(III) (abbreviated as: Ir(Prptz1-Me)3); fac-tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviated as: Ir(iPrpmi)3), tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviated as: Ir(dmpimpt-Me)3); and bis[2-(4',6'-difluorophenyl)pyridinium-N,C 2' ]iridium(III)tetrakis(1-pyrazolyl)borate (abbreviated as FIr6), bis[2-(4',6'-difluorophenyl)pyridinium-N,C 2' ] iridium (III) picolinate (abbreviated as: FIrpic), bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinium-N,C 2' Iridium(III) picolinate (abbreviated as: Ir(CF3ppy)2(pic)), bis[2- (4',6'-Difluorophenyl)pyridinium-N,C 2' Organometallic iridium complexes having phenylpyridine derivatives having electron-withdrawing groups as ligands, such as iridium (III) acetylacetonate (abbreviated as FIr(acac)). Among the above-mentioned metal complexes, organometallic iridium complexes having nitrogen-containing five-membered heterocyclic skeletons, such as 4H-triazole skeletons, 1H-triazole skeletons, and imidazole skeletons, are particularly preferred due to their high triplet excitation energy and excellent reliability and luminous efficiency.

[0162] Examples of substances having a luminescence peak in the green or yellow wavelength region include tris(4-methyl-6-phenylpyrimidinium)iridium(III) (abbreviated as Ir(mppm)3), tris(4-tert-butyl-6-phenylpyrimidinium)iridium(III) (abbreviated as Ir(tBuppm)3), (acetylacetonato)bis(6-methyl-4-phenylpyrimidinium)iridium(III) (abbreviated as Ir(mppm)2 (acac)), (acetylacetonate)bis(6-tert-butyl-4-phenylpyrimidinyl)iridium(III) (Abbreviation: Ir(tBuppm)2(acac)), (acetylacetonate)bis[4-(2-norbornyl)-6-phenylpyrimidinyl]iridium(III) (Abbreviation: Ir(nbppm)2(acac)), (acetylacetonate)bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidinyl]iridium(III) (Abbreviation: Ir(mpmppm)2(acac)), (acetylacetonate)bis[4,6-dimethyl-2-[6- Organometallic iridium complexes with a pyrimidine skeleton, such as (2,6-dimethylphenyl)-4-pyrimidinyl-κN3]phenyl-κC}iridium(III) (abbreviated as: Ir(dmppm-dmp)2(acac)), (acetylacetonate)bis(4,6-diphenylpyrimidinyl)iridium(III) (abbreviated as: Ir(dppm)2(acac)); organometallic iridium complexes with a pyrazine skeleton, such as (acetylacetonate)bis(3,5-dimethyl-2-phenylpyrazine)iridium(III) (abbreviated as: Ir(mppr-Me)2(acac)), (acetylacetonate)bis(5-isopropyl-3-methyl-2-phenylpyrazine)iridium(III) (abbreviated as: Ir(mppr-iPr)2(acac)); tris(2-phenylpyridinyl-N,C 2 ') Iridium (III) (abbreviated as: Ir(ppy)3), bis(2-phenylpyridinium-N,C 2' )iridium(III) acetylacetonate (abbreviated as: Ir(ppy)2(acac)), bis(benzo[h]quinolinolato)iridium(III) acetylacetonate (abbreviated as: Ir(bzq)2(acac)), tris(benzo[h]quinolinolato)iridium(III) (abbreviated as: Ir(bzq)3), tris(2-phenylquinolinolato-N,C 2′ )iridium(III) (abbreviated as: Ir(pq)3), bis(2-phenylquinoline-N,C 2' ) iridium (III) acetylacetonate (abbreviated as: Ir (pq) 2 (acac)) and other organometallic iridium complexes with a pyridine skeleton; bis (2, 4-diphenyl-1, 3-oxazole-N, C 2' )iridium(III) acetylacetonate (abbreviated as: Ir(dpo)2 (acac)), bis{2-[4'-(perfluorophenyl)phenyl]pyridine-N,C 2' Iridium (III) acetylacetonate (abbreviated as: Ir(p-PF-ph)2(acac)), bis(2-phenylbenzothiazole-N, C 2' ) organometallic iridium complexes such as iridium(III) acetylacetonate (abbreviated as Ir(bt)2(acac)); and rare earth metal complexes such as terbium(III) tris(acetylacetonate)(monophenanthroline) (abbreviated as Tb(acac)3(Phen)). Of these, organometallic iridium complexes with a pyrimidine skeleton are particularly preferred due to their significantly superior reliability and luminous efficiency.

[0163] In addition, examples of substances having a luminescence peak in the yellow or red wavelength region include (diisobutyrylmethane)bis[4,6-bis(3-methylphenyl)pyrimidinyl]iridium(III) (abbreviation: Ir(5mdppm)2(dibm)), bis[4,6-bis(3-methylphenyl)pyrimidinyl](dipivaloylmethane)iridium(III) (abbreviation: Ir(5mdppm)2(dpm)), bis[4,6-di(naphthalene-1-yl)pyrimidinyl](dipivaloylmethane)iridium(III) (abbreviation: Ir(5mdppm)2(dpm)), Abbreviation: Ir(d1npm)2(dpm)) and other organometallic iridium complexes with a pyrimidine skeleton; (acetylacetonato)bis(2,3,5-triphenylpyrazine)iridium(III) (abbreviation: Ir(tppr)2(acac)), bis(2,3,5-triphenylpyrazine)(dipivaloylmethane)iridium(III) (abbreviation: Ir(tppr)2(dpm)), (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxaline]iridium(III) (abbreviation: Ir(Fdpq)2 (acac)) and other organic metal iridium complexes with pyrazine skeletons; tris(1-phenylisoquinoline-N, C 2’ ) iridium (III) (abbreviated as: Ir(piq)3), bis(1-phenylisoquinoline-N, C 2’) iridium(III) acetylacetonate (abbreviated as Ir(piq)2(acac)) and other organometallic iridium complexes having a pyridine skeleton; platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum(II) (abbreviated as PtOEP); and rare earth metal complexes such as tris(1,3-diphenyl-1,3-propanedione)(monophenanthroline)europium(III) (abbreviated as Eu(DBM)3(Phen)) and tris[1-(2-thenoyl)-3,3,3-trifluoroacetone](monophenanthroline)europium(III) (abbreviated as Eu(TTA)3(Phen)). Among the above, organometallic iridium complexes having a pyrimidine skeleton are particularly preferred because they also have significantly excellent reliability and luminous efficiency. In addition, organometallic iridium complexes with a pyrazine skeleton can produce red light with good chromaticity.

[0164] Examples of materials capable of converting triplet excitation energy into luminescence include, in addition to phosphorescent compounds, thermally activated delayed fluorescence (TADF) materials. Therefore, descriptions of phosphorescent compounds can be considered as descriptions of thermally activated delayed fluorescence compounds. Thermally activated delayed fluorescence compounds are materials that have a small difference between the singlet excitation energy level and the triplet excitation energy level and have the ability to convert energy from triplet excitation energy to singlet excitation energy through antisystem crossing. Therefore, they can up-convert the triplet excited state to the singlet excited state (antisystem crossing) using minimal thermal energy and efficiently produce luminescence (fluorescence) from the singlet excited state. Furthermore, the conditions for efficiently obtaining thermally activated delayed fluorescence are as follows: the energy difference between the singlet excitation energy level and the triplet excitation energy level is preferably greater than 0 eV and less than 0.3 eV, more preferably greater than 0 eV and less than 0.2 eV, and even more preferably greater than 0 eV and less than 0.1 eV.

[0165] When the thermally activated delayed fluorescent compound is composed of one material, for example, the following materials can be used.

[0166] First, there are fullerenes or their derivatives, acridine derivatives such as proflavine, eosin, etc. In addition, there are metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd). Examples of the metal-containing porphyrin include protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF2(OEP)), protoporphyrin-tin fluoride complex (SnF2(Etio I)), octaethylporphyrin-platinum chloride complex (PtCl2OEP), and the like.

[0167] In addition, as a thermally activated delayed fluorescence compound composed of a single material, a heterocyclic compound having a π-electron-rich heteroaromatic skeleton and a π-electron-deficient heteroaromatic skeleton can also be used. Specifically, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazole-11-yl)-1,3,5-triazine (abbreviated as: PIC-TRZ), 2-{4-[3-(N-phenyl-9H-carbazole-3-yl)-9H-carbazole-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviated as: PCCzPTzn), 2-[4-(10H- phenoxazine-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviated as: PXZ-TRZ), 3-[4-(5-phenyl-5,10-dihydrophenazine-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviated as: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthene-9-one (abbreviated as: ACRXTN), bis[4- (9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), 10-phenyl-10H, 10'H-spiro[acridine-9,9'-anthracenes]-10'-one (abbreviation: ACRSA), etc. This heterocyclic compound has a π-electron-rich heteroaromatic skeleton and a π-electron-deficient heteroaromatic skeleton, so the electron transport property and the hole transport property are high, so it is preferred. In particular, among the π-electron-deficient heteroaromatic skeletons, the diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton) or the triazine skeleton is stable and has good reliability, so it is preferred. In addition, among the π-electron-rich heteroaromatic skeletons, the acridine skeleton, the phenoxazine skeleton, the phenothiazine skeleton, the furan skeleton, the thiophene skeleton and the pyrrole skeleton are stable and have good reliability, so it is preferred to have any one or more selected from the skeletons. As the pyrrole skeleton, it is particularly preferred to use an indole skeleton, a carbazole skeleton and a 9-phenyl-3,3'-bi-9H-carbazole skeleton. In addition, in a substance in which a π-electron-rich heteroaromatic skeleton and a π-electron-deficient heteroaromatic skeleton are directly bonded, the donor property of the π-electron-rich heteroaromatic skeleton and the acceptor property of the π-electron-deficient heteroaromatic skeleton are both strong, and the difference between the singlet excitation energy level and the triplet excitation energy level becomes small, so it is particularly preferred.

[0168] Furthermore, a material exhibiting thermally activated delayed fluorescence may be a material capable of generating a singlet excited state from a triplet excited state by antisystem crossing alone, or may be composed of a plurality of materials that form an exciplex (also called an exciplex).

[0169] As a host material for the light-emitting layer 140 , a hole-transporting material or an electron-transporting material can be used.

[0170] Although there is no particular limitation on the host material that can be used for the light-emitting layer, examples thereof include metal complexes such as tris(8-hydroxyquinolinolato)aluminum(III) (abbreviated as Alq3), tris(4-methyl-8-hydroxyquinolinolato)aluminum(III) (abbreviated as Almq3), bis(10-hydroxybenzo[h]quinolinolato)beryllium(II) (abbreviated as BeBq2), bis(2-methyl-8-hydroxyquinolinolato)(4-phenylphenol)aluminum(III) (abbreviated as BAlq), bis(8-hydroxyquinolinolato)zinc(II) (abbreviated as Znq), bis[2-(2-benzoxazolyl)phenol]zinc(II) (abbreviated as ZnPBO), and bis[2-(2-benzothiazolyl)phenol]zinc(II) (abbreviated as ZnBTZ); 2- (4-Biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviated as: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviated as: OXD-7), 3-(4-biphenyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviated as: TAZ), 2,2',2"-(1,3,5-phenyltriyl)tris(1-phenyl-1H-benzimidazole) (abbreviated as: TPBI), bathocuproin (abbreviated as: BCP), 9-[4-(5-phenyl-1,3,4- Heterocyclic compounds such as oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviated as CO11); aromatic amine compounds such as 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviated as NPB or α-NPD), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviated as TPD), and 4,4'-bis[N-(spiro-9,9'-difluoren-2-yl)-N-phenylamino]biphenyl (abbreviated as BSPB). In addition, anthracene derivatives, phenanthrene derivatives, pyrene derivatives, derivatives, dibenzo[g,p] Condensed polycyclic aromatic compounds such as derivatives. Specific examples include 9,10-diphenylanthracene (abbreviation: DPAnth), N,N-diphenyl-9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole-3-amine (abbreviation: CzA1PA), 4-(10-phenyl-9-anthracenyl)triphenylamine (abbreviation: DPhPA), YGAPA, PCAPA, N,9-diphenyl-N-{4-[4-(10-phenyl-9-anthracenyl)phenyl]phenyl}-9H-carbazole-3-amine (abbreviation: PCAPBA), 2PCAPA, 6,12-dimethoxy-5,11-diphenyl DBC1, 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviated as: CzPA), 3,6-diphenyl-9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviated as: DPCzPA), 9,10-bis(3,5-diphenylphenyl)anthracene (abbreviated as: DPPA), 9,10-di(2-naphthyl)anthracene (abbreviated as: DNA), 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviated as: t-BuDNA), 9,9'-bianthracene (abbreviated as: BANT), 9,9'-(stilbene-3,3'-diyl)phenanthrene (abbreviated as: DPNS), 9,9'-(stilbene-4,4'-diyl)phenanthrene (abbreviated as: DPNS2), and 1,3,5-tri(1-pyrenyl)benzene (abbreviated as: TPB3), etc. From these and other substances, one or more substances having a larger energy gap than the above-mentioned luminescent material can be selected. In addition, when the luminescent material is a phosphorescent compound, a substance having a larger triplet excitation energy than the triplet excitation energy of the luminescent material can be selected as the host material.

[0171] When multiple materials are used as the host material of the light-emitting layer, it is preferred to use a combination of two compounds that form exciplexes. In this case, various carrier transport materials can be used as appropriate. It is particularly preferred to combine an electron transport material and a hole transport material in order to efficiently form an exciplex.

[0172] This is because, when combining an electron-transporting material and a hole-transporting material to form a host material for forming an exciplex, adjusting the mixing ratio of the electron-transporting and hole-transporting materials makes it easier 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 prevent the region where electrons and holes recombine in the light-emitting layer from being biased to one side. This prevents the region where recombination occurs from being biased to one side, thereby improving the reliability of the light-emitting element.

[0173] As electron transport materials, metal complexes containing zinc or aluminum, π-electron-deficient heteroaromatic compounds such as nitrogen-containing heteroaromatic compounds, etc. can be used. Specifically, bis(10-hydroxybenzo[h]quinolinolato)beryllium(II) (abbreviated as BeBq2), bis(2-methyl-8-hydroxyquinolinolato)(4-phenylphenol)aluminum(III) (abbreviated as BAlq), bis(8-hydroxyquinolinolato)zinc(II) (abbreviated as Znq), bis[2-(2-benzoxazolyl)phenol]zinc(II) (abbreviated as ZnPBO) or bis[2-(2-benzothiazolyl)phenol]zinc(II) (abbreviated as ZnPBO) can be mentioned. metal complexes such as ZnBTZ), 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviated as PBD), 3-(4-biphenyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviated as TAZ), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviated as OXD-7), 9-[4-(5-phenyl-1,3,Heterocyclic compounds having an azole skeleton, such as 2-[4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviated as CO11), 2,2',2"-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviated as TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviated as mDBTBIm-II), 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as 2mDBTPDBq-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviated as 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-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-diphenyl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), heterocyclic compounds having a diazine skeleton such as 4-{3-[3'-(9H-carbazol-9-yl)biphenyl-3-yl}benzofuro[3,2-d]pyrimidine (abbreviation: 4mCzBPBfpm), 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: PCCzPTzn), 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviation: PCCzPTzn), 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviation: PCCzPTzn), 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviation: PCCzPTzn), 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviation: Heterocyclic compounds with a triazine skeleton, such as triazine (abbreviated as TmPPPyTz), 2,4,6-tris(2-pyridine)-1,3,5-triazine (abbreviated as 2Py3Tz), and heterocyclic compounds with a pyridine skeleton, such as 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviated as 35DCzPPy), 1,3,5-tris[3-(3-pyridyl)phenyl]benzene (abbreviated as TmPyPB). Among them, heterocyclic compounds with a diazine skeleton and a triazine skeleton and heterocyclic compounds with a pyridine skeleton are preferred because they have high reliability. In particular, heterocyclic compounds with a diazine (pyrimidine or pyrazine) skeleton and a triazine skeleton have high electron transport properties and also contribute to reducing the driving voltage.

[0174] As hole transport materials, it is preferred to use π-electron-rich heteroaromatics (such as carbazole derivatives or indole derivatives) or aromatic amines. Specifically, 2-[N-(9-phenylcarbazole-3-yl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviated as: PCASF), 4,4',4"-tris[N-(1-naphthyl)-N-phenylamino]triphenylamine (abbreviated as: 1'-TNATA), 2,7-bis[N-(4-diphenylaminophenyl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviated as: DPA2SF), N,N'-bis(9-phenylcarbazole-3-yl)-N,N'-diphenylbenzene-1,3-diamine (abbreviated as: PCA2B), N-(9,9-dimethyl-2-diphenylamino-9H-fluorene-7-yl)diphenylamine (abbreviated as: DPNF), N, N', N"-triphenyl-N, N', N"-tris(9-phenylcarbazol-3-yl)benzene-1,3,5-triamine (abbreviated as PCA3B), 2-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviated as PCASF), 2-[N-(4-diphenylaminophenyl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviated as DPASF), N,N'-bis[4-(carbazol-9-yl)phenyl]-N,N'-diphenyl-9,9-dimethylfluorene-2,7-diamine (abbreviated as YGA2F), 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviated as NPB), N,N'- Bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviated as TPD), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviated as DPAB), 4,4'-bis[N-(spiro-9,9'-difluoren-2-yl)-N-phenylamino]biphenyl (abbreviated as BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviated as BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviated as 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'-diphenylamine (abbreviated as DNTPD), 3,6-bis[N-(4-diphenylaminophenyl)-N-(1-naphthyl)amino]-9-phenylcarbazole (abbreviated as PCzTPN2), 3,6-bis[N-(9-phenylcarbazole-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviated as PCzPCA2), 4-phenyl-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviated as PCBA1BP), 4,4'-diphenyl-4"-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviated as PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviated as PCBANB), 4,4'-di(1-naphthyl)-4"-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviated as PCBNBB), 3- [N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole (abbreviated as PCzPCN1), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviated as PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-spiro-9,9'-bifluoren-2-amine (abbreviated as Compounds having an aromatic amine skeleton, such as N-(4-biphenyl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9-phenyl-9H-carbazol-3-amine (abbreviated as: PCBiF), and N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviated as: PCBBiF); 1,Compounds having a carbazole skeleton, such as 3-bis(N-carbazolyl)benzene (abbreviated as mCP), 4,4'-bis(N-carbazolyl)biphenyl (abbreviated as CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviated as CzTP), 9-phenyl-9H-3-(9-phenyl-9H-carbazol-3-yl)carbazole (abbreviated as PCCP); 4,4',4"-(benzene-1,3,5-triyl)tris(dibenzothiophene) (abbreviated as DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluorene-9 Compounds having a thiophene skeleton, such as 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviated as DBTFLP-IV); and compounds having a furan skeleton, such as 4,4',4"-(benzene-1,3,5-triyl)tris(dibenzofuran) (abbreviated as DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviated as mmDBFFLBi-II). Among these, compounds having an aromatic amine skeleton and a carbazole skeleton are preferred because they have high reliability and high hole transport properties, and also contribute to lowering the driving voltage.

[0175] The combination of main materials that form the excited complex is not limited to the above-mentioned compounds. Compounds in which carriers can move and can form an excited complex can be used, wherein the luminescence of the excited complex can overlap with the absorption band on the longest wavelength side in the absorption spectrum of the luminescent material (equivalent to the absorption of the transition from the singlet ground state to the singlet excited state of the luminescent material), and other materials can also be used.

[0176] As a host material for the light-emitting layer, a thermally activated delayed fluorescent material may also be used.

[0177] The electron-transporting material used in the light-emitting layer can be the same as the electron-transporting material used in the electron-injecting layer. This simplifies the production of the light-emitting element and reduces the production cost of the light-emitting element.

[0178] Electron transport layer and buffer layer The electron transport layer 118 and the buffer layer 127 are layers containing a substance with high electron transport properties. Examples of organic compounds that can be used in 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, and the like. In addition, organic compounds that have a tridentate or tetradentate interaction with metals can also be used as compounds that can be used in the electron injection layer 130.

[0179] As the above-mentioned metal complexes having 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) (abbreviated as: Znq), bis[2-(2-benzoxazolyl)phenol]zinc(II) (abbreviated as: ZnPBO), bis[2-(2-benzothiazolyl)phenol]zinc(II) (abbreviated as: ZnBTZ) and other metal complexes can be used. In addition, 2-(4-biphenyl)-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"-biphenyl)-1,2,4-triazole (abbreviation: TAZ), 3-(4-tert-butylphenyl)-4-(4 Heterocyclic compounds having an azole skeleton, such as 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), ... Benzo[f,h]quinoxaline (abbreviated as: 2mDBTPDBq-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviated as: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviated as: 2mCzBPDBq), 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as: 2CzPDBq-III), 7-[3-(dibenzothiophene-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviated as: 2mDBTBPDBq-II), thiophen-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-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothiophen-4-yl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II),6mCzP2Pm), 4-{3-[3'-(9H-carbazol-9-yl)]biphenyl-3-yl}benzofuro[3,2-d]pyrimidine (abbreviation: 4mCzBPBfpm), heterocyclic compounds having a diazine skeleton such as 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: Tm Heterocyclic compounds with a pyridine skeleton, such as PPPyTz), 2,4,6-tris(2-pyridine)-1,3,5-triazine (abbreviated as: 2Py3Tz), 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviated as: 35DCzPPy), 1,3,5-tris[3-(3-pyridyl)phenyl]benzene (abbreviated as: TmPyPB), bathocuproin (abbreviated as: BCP), 2,9-bis(naphthalene-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviated as: NBPhen). Among them, heterocyclic compounds with a diazine skeleton and a triazine skeleton and heterocyclic compounds with a pyridine skeleton have high reliability and are therefore 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 here mainly have an electron mobility of 1×10, -6 cm 2 In addition, a substance other than the above substances may be used for the electron injection layer 130 as long as the electron-transporting property is higher than the hole-transporting property.

[0180] The electron transport layer 118 and the buffer layer 127 are not limited to single layers, and two or more layers composed of the above-mentioned substances may be stacked.

[0181] Furthermore, a layer for controlling the movement of electron carriers can be provided between the electron transport layer 118 and the light-emitting layer 140. This layer is formed by adding a small amount of a substance with high electron-trapping properties to the aforementioned material with high electron transport properties. By suppressing the movement of electron carriers, the carrier balance can be adjusted. This structure is very effective in suppressing problems caused by electrons passing through the light-emitting layer (such as a reduction in device life).

[0182] The electron-transporting material for the electron transport layer can be the same as the electron-transporting material for the electron injection layer. Furthermore, the electron-transporting material for the electron transport layer can be the same as the electron-transporting material for the light-emitting layer. This simplifies the manufacture of the light-emitting element, thereby reducing the manufacturing cost of the light-emitting element.

[0183] In addition, the 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 method, coating method, gravure printing, etc. In addition, as the 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 high molecular compounds (oligomers, dendrimers, polymers, etc.) can also be used.

[0184] As quantum dots, colloidal quantum dots, alloy quantum dots, core-shell quantum dots, core-type quantum dots, etc. can be used. In addition, quantum dots containing elements from 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), and aluminum (Al) can be used.

[0185] As the liquid medium used for the wet method, for example, 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, decahydronaphthalene, and dodecane; organic solvents such as N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO).

[0186] Examples of polymer compounds that can be used for the light-emitting layer include polyphenylene vinylene (PPV) derivatives such as poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene] (abbreviated as MEH-PPV) and poly(2,5-dioctyl-1,4-phenylene vinylene); polyfluorene derivatives such as poly(9,9-di-n-octylfluorenyl-2,7-diyl) (abbreviated as PF8), poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazole-4,8-diyl)] (abbreviated as F8BT), Poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-(2,2'-bithiophene-5,5'-diyl)] (abbreviated as 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) (abbreviated as: P3HT), etc., polyphenylene derivatives, etc. Alternatively, the aforementioned polymer compounds, poly(N-vinylcarbazole) (abbreviated as PVK), poly(2-vinylnaphthalene), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (abbreviated as PTAA), and the like may be doped with a luminescent low molecular weight compound and used in the light-emitting layer. The fluorescent compounds exemplified above may be used as the luminescent low molecular weight compound.

[0187] A Pair of Electrodes The electrodes 101 and 102 function as an anode and a cathode of the light-emitting element. The electrodes 101 and 102 can be formed using a metal, an alloy, a conductive compound, a mixture thereof, a laminate thereof, or the like.

[0188] One of the electrode 101 and the electrode 102 is preferably formed using a conductive material having a function of reflecting light. Examples of the conductive material include aluminum (Al) or an alloy containing Al. Examples of the alloy containing Al include alloys containing Al and L (L represents one or more of titanium (Ti), neodymium (Nd), nickel (Ni) and lanthanum (La)), such as alloys containing Al and Ti or alloys containing Al, Ni and La. Aluminum has low resistivity and high light reflectivity. In addition, since aluminum is contained in large quantities in the earth's crust and is inexpensive, the use of aluminum can reduce the manufacturing cost of the light-emitting element. In addition, silver (Ag) is suitable for use as an electrode material because it has high light reflectivity. In addition, Ag is a transition metal of Group 11. When Ag is used as the cathode of a light-emitting element in which Ag is used in the electron injection layer of one embodiment of the present invention, the adhesion between the electrode and the electron injection layer is improved, so it is preferred. In addition, alloys containing Ag, 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 alloys containing silver, for example, the following alloys can be mentioned: alloys containing silver, palladium, and copper; alloys containing silver and copper; alloys containing silver and magnesium; alloys containing silver and nickel; alloys containing silver and gold; and alloys containing silver and ytterbium. In addition to the above materials, transition metals such as tungsten, chromium (Cr), molybdenum (Mo), copper, and titanium can be used.

[0189] In addition, light obtained from the light-emitting layer is extracted through one or both of the electrodes 101 and 102. Therefore, at least one of the electrodes 101 and 102 is preferably formed using a conductive material having a light-transmitting function. Examples of such conductive materials include those 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 Conductive materials with a resistance of Ω·cm or less.

[0190] Alternatively, the electrodes 101 and 102 may be formed using a conductive material having both a light transmitting function and a light reflecting function. Examples of such conductive materials include those 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 -2Conductive materials with a resistance of Ω·cm or less. For example, one or more conductive metals, alloys, and conductive compounds can be used. Specifically, for example, indium tin oxide (hereinafter referred to as ITO), indium tin oxide containing silicon or silicon oxide (abbreviated as: ITSO), indium zinc oxide (Indium Zinc Oxide), indium oxide-tin oxide containing titanium, indium-titanium oxide, indium oxide containing tungsten oxide and zinc oxide, and other metal oxides can be used. In addition, a metal film having a thickness that allows light to pass (preferably a thickness of more than 1 nm and less than 30 nm) can be used. As the metal, for example, alloys of Ag, Ag and Al, Ag and Mg, Ag and Au, and Ag and Yb can be used.

[0191] 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 can be used, such as the oxide conductor represented by ITO, an oxide semiconductor, or an organic conductor containing organic matter. As an organic conductor containing organic matter, for example, a composite material containing a mixed organic compound and an electron donor (donor), a composite material containing a mixed organic compound and an electron acceptor (acceptor), etc. can be cited. Inorganic carbon materials such as graphene can also be used. In addition, the resistivity of the material is preferably 1×10 5 Ω·cm or less, more preferably 1×10 4 Ω·cm or less.

[0192] Alternatively, one or both of the electrode 101 and the electrode 102 may be formed by stacking a plurality of the above materials.

[0193] In order to improve the light extraction efficiency, a material having a refractive index higher than that of an electrode can be formed in contact with an electrode having a function of transmitting light. As such a material, as long as it has the function of transmitting visible light, it can be a conductive material or a non-conductive material. For example, in addition to the above-mentioned oxide conductors, oxide semiconductors and organic substances can also be cited. As organic substances, for example, materials exemplified as light-emitting layers, hole injection layers, hole transport layers, electron transport layers or electron injection layers can be cited. In addition, inorganic carbon materials or metal films having a thickness sufficient to transmit light can also be used, or multiple layers having a thickness of several nm to several tens of nm can be stacked.

[0194] When the electrode 101 or the electrode 102 is used as a cathode, it is preferable to use a material having a small work function (3.8 eV or less).

[0195] When the electrode 101 or the electrode 102 is used as an anode, it is preferable to use a material having a large work function (4.0 eV or higher).

[0196] Electrodes 101 and 102 may also be formed by stacking a conductive material having a light-reflecting function and a conductive material having a light-transmitting function. In this case, electrodes 101 and 102 can adjust the optical distance, thereby resonating light of a desired wavelength from each light-emitting layer and enhancing the light of that wavelength, which is preferable.

[0197] As a film forming method for the electrodes 101 and 102 , sputtering, vapor deposition, printing, coating, MBE (Molecular Beam Epitaxy), CVD, pulsed laser deposition, ALD (Atomic Layer Deposition), or the like can be appropriately used.

[0198] Substrate The light-emitting element of one embodiment of the present invention can be manufactured over a substrate made of glass, plastic, etc. The order of stacking layers on the substrate may be sequentially stacked from the electrode 101 side or from the electrode 102 side.

[0199] In addition, as a substrate for forming a light-emitting element of one embodiment of the present invention, for example, glass, quartz or plastic can be used. Alternatively, a flexible substrate can also be used. A flexible substrate is a flexible substrate, such as a plastic substrate made of polycarbonate or polyarylate. In addition, a film, an inorganic vapor-deposited film, etc. can be used. Note that other materials can be used as long as they serve as a support in the manufacturing process of the light-emitting element and the optical element. Alternatively, any material can be used as long as it has the function of protecting the light-emitting element and the optical element.

[0200] For example, in this specification, etc., various substrates can be used to form light-emitting elements. There is no particular limitation on the type of substrate. As examples of the substrate, for example, a semiconductor substrate (for example, a single crystal substrate or a silicon substrate), an SOI substrate, a glass substrate, a quartz substrate, a plastic substrate, a metal substrate, a stainless steel substrate, a substrate with a stainless steel foil, a tungsten substrate, a substrate with a tungsten foil, a flexible substrate, a bonding film, a cellulose nanofiber (CNF) containing a fibrous material, or paper or a substrate film can be used. As examples of glass substrates, there are barium borosilicate glass, aluminoborosilicate glass, soda-lime glass, etc. As flexible substrates, bonding films, substrate films, etc., the following examples can be given. For example, plastics represented by polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), and polytetrafluoroethylene (PTFE) can be given. Alternatively, as an example, resins such as acrylic resin can be given. Alternatively, as an example, polypropylene, polyester, polyvinyl fluoride, or polyvinyl chloride can be given. Alternatively, examples include polyamide, polyimide, aramid, epoxy resin, inorganic vapor-deposited film, and paper.

[0201] Alternatively, a flexible substrate can be used as the substrate, and the light-emitting element can be formed directly on the flexible substrate. Alternatively, a peeling layer can be provided between the substrate and the light-emitting element. The peeling layer can be used when part or all of the light-emitting element is manufactured on the peeling layer, and then separated from the substrate and transferred to another substrate. In this case, the light-emitting element can also be transferred to a substrate with low heat resistance or a flexible substrate. In addition, as the above-mentioned peeling layer, for example, a laminated structure of an inorganic film such as a tungsten film and a silicon oxide film, or a structure in which a resin film such as a polyimide is formed on a substrate, can be used.

[0202] That is, a light-emitting element can be formed using one substrate and then transferred to another substrate. Examples of substrates to which the light-emitting element is transferred include, in addition to the aforementioned substrates, cellophane substrates, stone substrates, wood substrates, cloth substrates (including natural fibers (silk, cotton, linen), synthetic fibers (nylon, polyurethane, polyester), or regenerated fibers (acetate, cuprammonium, rayon, regenerated polyester), etc.), leather substrates, and rubber substrates. By using these substrates, it is possible to manufacture light-emitting elements that are not easily damaged, have high heat resistance, achieve lightweight properties, or achieve thinness.

[0203] Alternatively, a field effect transistor (FET) may be formed over the substrate, and the light emitting element 150 may be fabricated on an electrode electrically connected to the FET. This allows fabrication of an active matrix display device in which driving of the light emitting element is controlled by the FET.

[0204] The structure described in this embodiment can be implemented in combination with the structures described in other embodiment modes as appropriate.

[0205] (Implementation Method 2) In this embodiment, a light-emitting element having a structure different from that of the light-emitting element described in Embodiment 1 and a light-emitting mechanism of the light-emitting element are described with reference to FIG3. Figure 1A The same hatching is shown with Figure 1A The same function as the part, and sometimes the reference numerals are omitted. Figure 1A Parts having the same functions as shown are denoted by the same reference numerals, and detailed description thereof may be omitted.

[0206] <Structural Example 4 of Light-Emitting Element> FIG3 is a schematic cross-sectional view of the light emitting element 250 a and the light emitting element 250 b .

[0207] The light-emitting element 250a and the light-emitting element 250b include an electrode 101, an electrode 102, an electrode 103, and an electrode 104 over a substrate 200. Furthermore, at least a light-emitting unit 106, a light-emitting unit 108, and an electron injection layer 130 are provided between the electrodes 101 and 102, between the electrodes 102 and 103, and between the electrodes 102 and 104. Furthermore, 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.

[0208] The charge generation layer 115 sandwiched between the light-emitting unit 106 and the light-emitting unit 108 can have a structure in which, when a voltage is applied between the electrode 101 and the electrode 102, electrons are injected into one light-emitting unit and holes are injected into the other light-emitting unit. For example, in FIG1 , 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 holes into the light-emitting unit 108.

[0209] 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. Furthermore, 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.

[0210] Here, as shown in FIG3 , the electron injection layer 130 is preferably adjacent to the electron transport layer 113 and provided between the light-emitting unit 108 and the electron transport layer 113. Furthermore, as shown in FIG3 , the charge generation layer 115 is preferably adjacent to the electron injection layer 130 and provided 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.

[0211] In this embodiment, the electrodes 101, 103, and 104 are anodes and the electrode 102 is a cathode, but the structure of the light-emitting element 250a and the light-emitting element 250b is not limited to this. That is, the electrodes 101, 103, and 104 can also 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 stacked in sequence 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 stacked in sequence from the anode side of the light-emitting unit 108.

[0212] The structure of the light-emitting element 250a and the light-emitting element 250b is not limited to the structure shown in Figure 3. It includes at least a light-emitting layer 140, a light-emitting layer 170, a charge generation layer 115 and an electron injection layer 130, and may include a hole injection layer 111, a hole injection layer 116, a hole transport layer 112, a hole transport layer 117, an electron transport layer 113, an electron transport layer 118, and an electron injection layer 119, or may not include these layers.

[0213] The layers described above can be formed between a pair of electrodes based on their functions. Specifically, a layer may be included between a pair of electrodes to reduce the injection barrier for holes or electrons, improve hole or electron transport, hinder hole or electron transport, or suppress quenching caused by the electrodes.

[0214] As in the light-emitting unit 108, when the surface on the anode side of the light-emitting unit contacts the charge generation layer 115, sometimes the charge generation layer 115 can also have the function of the hole injection layer of the light-emitting unit 108, so the hole injection layer may not be set in the light-emitting unit.

[0215] Although FIG3 illustrates a light-emitting element having two light-emitting units, a light-emitting element having three or more stacked light-emitting units may also be used. As shown in light-emitting elements 250a and 250b, by arranging multiple light-emitting units between a pair of electrodes, separated by a charge generation layer, a light-emitting element can be realized that can achieve high brightness while maintaining a low current density and a longer life. Furthermore, a light-emitting element with low power consumption can be realized.

[0216] In light-emitting element 250a, electrodes 101, 103, and 104 reflect visible light, while electrode 102 transmits visible light. In light-emitting element 250b, electrodes 101, 103, and 104 transmit visible light, while electrode 102 reflects visible light.

[0217] Therefore, light emitted by the light-emitting element 250a is emitted to the outside through the electrode 102, and light emitted by the light-emitting element 250b is emitted to the outside through the electrodes 101, 103, and 104. Note that one embodiment of the present invention is not limited to this, 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 be employed.

[0218] Electrode 101 includes a conductive layer 101a and a conductive layer 101b on and in contact with conductive layer 101a. Electrode 103 includes a conductive layer 103a and a conductive layer 103b on and in contact with conductive layer 103a. Electrode 104 includes a conductive layer 104a and a conductive layer 104b on and in contact with conductive layer 104a.

[0219] Conductive layer 101b, conductive layer 103b, and conductive layer 104b have a function of transmitting visible light. Furthermore, in light-emitting element 250a, conductive layer 101a, conductive layer 103a, and conductive layer 104a have a function of reflecting visible light. Furthermore, in light-emitting element 250b, conductive layer 101a, conductive layer 103a, and conductive layer 104a have a function of transmitting visible light.

[0220] Figure 3A The light emitting element 250a and Figure 3B The light-emitting element 250b shown includes partition walls 145 between the region 222B sandwiched between the electrodes 101 and 102, the region 222G sandwiched between the electrodes 102 and 103, and the region 222R sandwiched between the electrodes 102 and 104. The partition walls 145 are insulating. They cover the ends of the electrodes 101, 103, and 104 and include openings that overlap with the electrodes. The provision of the partition walls 145 allows the electrodes on the substrate 200 in each region to be divided into islands.

[0221] FIG3 shows an example 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 arranged in each region, but they can also be separately arranged in each region.

[0222] In the light-emitting element 250a and the light-emitting element 250b of one embodiment of the present invention, by applying a voltage between a pair of electrodes (electrode 101 and electrode 102) in region 222B, between a pair of electrodes (electrode 102 and electrode 103) in region 222G, and between a pair of electrodes (electrode 102 and electrode 104) in 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, thereby flowing current. 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. And, the injected carriers (electrons and holes) recombine to form excitons. In the light-emitting layer 140 and the light-emitting layer 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 layer 140 and the light-emitting layer 170 is in an excited state, thereby obtaining light from the light-emitting material.

[0223] The light-emitting layer 140 and the light-emitting layer 170 preferably include one or more light-emitting materials that emit light in purple, blue, blue-green, green, yellow-green, yellow, yellow-orange, orange, and red.

[0224] Light-emitting layer 140 and light-emitting layer 170 may also have a two-layer stacked structure. By using two light-emitting materials, a first compound and a second compound, capable of emitting different colors, as the two light-emitting layers, multiple light emission colors can be simultaneously obtained. In particular, the light-emitting materials used in each light-emitting layer are preferably selected so that the light emitted by light-emitting layer 140 and light-emitting layer 170, when combined, produces white or near-white light.

[0225] The light-emitting layer 140 and the light-emitting layer 170 may have a stacked structure of three or more layers, and may include a layer without a light-emitting material.

[0226] Light-emitting elements 250a and 250b include a substrate 220 provided with optical elements 224B, 224G, and 224R in the direction in which light emitted from regions 222B, 222G, and 222R is extracted. Light emitted from each region is emitted outside the light-emitting element through each optical element. That is, light emitted from region 222B is emitted through optical element 224B, light emitted from region 222G is emitted through optical element 224G, and light emitted from region 222R is emitted through optical element 224R.

[0227] Optical element 224B, optical element 224G, and optical element 224R selectively transmit light of a specific color from incident light. For example, light emitted from region 222B passes through optical element 224B as blue light, light emitted from region 222G passes through optical element 224G as green light, and light emitted from region 222R passes through optical element 224R as red light.

[0228] exist Figure 3A and Figure 3B The blue (B) light, green (G) light, and red (R) light emitted from each region through each optical element are schematically shown by dotted arrows. Figure 3A The light emitting element 250a shown is a top emission type light emitting element. Figure 3B The light emitting element 250b shown is a bottom emission type light emitting element.

[0229] A light-shielding layer 223 is included between each optical element. Light-shielding layer 223 shields light emitted from adjacent areas. Alternatively, a structure may be employed without light-shielding layer 223. Furthermore, one or more of optical element 224B, optical element 224G, and optical element 224R may be omitted. By omitting optical element 224B, optical element 224G, or optical element 224R, the efficiency of extracting light emitted from the light-emitting element can be improved.

[0230] The charge generation layer 115 can be formed using a material in which an electron acceptor (acceptor) is added to a hole-transporting material or a material in which an electron donor (donor) is added to an electron-transporting material.

[0231] Here, in order to reduce the driving voltage of the light-emitting element, it is preferable to adopt a structure in which the electrons generated in the charge generation layer 115 are smoothly injected and transported to the electron transport layer 113 by lowering the electron injection barrier from the charge generation layer 115 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 need to have high electron injectability, an alkali metal such as lithium (Li) and cesium (Cs) or a compound thereof, or an alkaline earth metal such as calcium (Ca) or a compound thereof is used for the electron injection layer. However, when such metals and such compounds are used for the electron injection layer 130, for example, as shown in FIG4 , when a voltage is applied between the counter electrode 103 and the electrode 102 to cause a current to flow through the region 222G, a current may also flow through the region 222B and the region 222R adjacent to the region 222G via the electron injection layer 130 and the electron transport layer 113, resulting in a phenomenon (referred to as crosstalk) in which light is emitted not only from the region 222G but also from the adjacent regions 222B and 222R. Furthermore, in FIG4 , the currents flowing through the regions 222G, 222R, and 222B are indicated by solid arrows.

[0232] When crosstalk occurs in a light-emitting element, light is emitted not only from a desired area (e.g., area 222G) but also from other areas (e.g., areas 222B and 222R), which sometimes results in a decrease in the color purity or luminous intensity of the light emitted by light-emitting element 250a and light-emitting element 250b.

[0233] One of the reasons for the crosstalk is that the alkali metal, alkaline earth metal or its compound used for the electron injection layer 130 sandwiched by 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 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, the metal with a small atomic number easily diffuses into the electron transport layer 113. Therefore, in order to suppress crosstalk, the electron injection layer 130 preferably does not have alkali metals and alkaline earth metals. On the other hand, when an alkali metal, alkaline earth metal or its compound is 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 high, electrons are not easily injected into the electron transport layer 113, so sometimes the driving voltage of the light-emitting element becomes high or the luminous efficiency decreases.

[0234] Therefore, in order to reduce the driving voltage of the light-emitting element, improve the luminous efficiency, and suppress crosstalk, it is preferable to use a metal that has excellent electron injection properties and does not diffuse easily into the organic compound when mixed with the organic compound for the electron injection layer 130. The metal that does not diffuse easily used in the electron injection layer 130 is preferably a metal with a large atomic radius. In addition, a metal with a large atomic weight is preferably used.

[0235] Here, a light-emitting element according to one embodiment of the present invention comprises a composite material of an organic compound and a metal having a function of interacting with a metal in a tridentate or quadridentate manner. As the metal, a metal having a large atomic weight or atomic radius belonging to Groups 3 to 13 can be suitably used. Therefore, one embodiment of the present invention can provide a light-emitting element with suppressed crosstalk.

[0236] In particular, since transition metals have a large atomic weight and are less likely to diffuse into organic compounds, a light-emitting element with suppressed crosstalk can be provided.

[0237] Alternatively, the light-emitting unit 106, the light-emitting unit 108, and the charge generation layer 115 can be formed by vapor deposition (including vacuum vapor deposition), inkjet printing, coating, gravure printing, or the like.

[0238] The structure described in this embodiment can be implemented in combination with the structures described in other embodiment modes as appropriate.

[0239] (Implementation 3) In this embodiment, referring to Figure 5A and Figure 5B A light-emitting device using the light-emitting element described in Embodiments 1 and 2 will be described.

[0240] Figure 5A is a top view showing a light emitting device, Figure 5B It is along Figure 5A , a cross-sectional view taken along lines AB and CD in FIG. The light-emitting device includes a driver circuit portion (source-side driver circuit) 601 for controlling the light emission of the light-emitting element, a pixel portion 602, and a driver circuit portion (gate-side driver circuit) 603, indicated by dashed lines. Reference numeral 604 denotes a sealing substrate, reference numeral 625 denotes a desiccant, reference numeral 605 denotes a sealant, and the space within the space surrounded by sealant 605 is space 607.

[0241] Furthermore, the lead wiring 608 is used to transmit signals input to the source-side driver circuit 601 and the gate-side driver circuit 603, and receives video signals, clock signals, start signals, reset signals, and the like from an FPC (flexible printed circuit) 609, which serves as an external input terminal. Although only an FPC is shown here, a printed wiring board (PWB) may also be attached to the FPC. The light-emitting device in this specification includes not only the light-emitting device itself but also a light-emitting device attached with an FPC or PWB.

[0242] Next, refer to Figure 5B The cross-sectional structure of the light emitting device is described below. A driver circuit portion and a pixel portion are formed on an element substrate 610. Here, a source-side driver circuit 601 serving as the driver circuit portion and one pixel in the pixel portion 602 are shown.

[0243] In addition, a CMOS circuit combining an n-channel TFT 623 and a p-channel TFT 624 is formed in the source-side driver circuit 601. Alternatively, the driver circuit may be formed using various CMOS circuits, PMOS circuits, or NMOS circuits. Furthermore, while this embodiment shows a driver-integrated type in which the driver circuit is formed on the substrate, this structure is not required, and the driver circuit may also be formed externally rather than on the substrate.

[0244] 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. Furthermore, an insulator 614 is formed to cover the end of the first electrode 613. The insulator 614 can be formed using a positive photosensitive resin film.

[0245] Furthermore, to improve the coverage of the film formed on insulator 614, the upper or lower end of insulator 614 is formed into a curved surface. For example, when photosensitive acrylic resin is used as the material for insulator 614, it is preferable to form a curved surface only at the upper end of insulator 614. The radius of curvature of this curved surface is 0.2 μm or more and 0.3 μm or less. Insulator 614 can be made of either a negative-type photosensitive material or a positive-type photosensitive material.

[0246] An EL layer 616 and a second electrode 617 are formed over the first electrode 613. A material having a high work function is preferably used as the material for the first electrode 613, which serves as the anode. For example, in addition to single-layer films such as an ITO film, an indium tin oxide film containing silicon, an indium oxide film containing 2% to 20% by weight of zinc oxide, a titanium nitride film, a chromium film, a tungsten film, a Zn film, and a Pt film, a stacked film consisting of a titanium nitride film and a film primarily composed of aluminum, or a three-layer stacked film consisting of a titanium nitride film, a film primarily composed of aluminum, and a titanium nitride film can also be used. Note that a stacked structure also reduces wiring resistance, enabling good ohmic contact and enabling the use of the anode.

[0247] The EL layer 616 is formed by various methods such as vapor deposition using a vapor deposition mask, inkjet, and spin coating. A low molecular weight compound or a high molecular weight compound (including an oligomer and a dendrimer) may be used as a material constituting the EL layer 616.

[0248] The material of the second electrode 617, which is formed on the EL layer 616 and serves as a cathode, is preferably a material having a small work function (e.g., Al, Mg, Li, Ca, or alloys or compounds thereof (e.g., MgAg, MgIn, AlLi)). Note that when light generated in the EL layer 616 is transmitted through the second electrode 617, it is preferable to use a stacked layer composed of a thin metal film with a reduced film thickness and a transparent conductive film (e.g., ITO, indium oxide containing 2 wt% to 20 wt% zinc oxide, indium tin oxide containing silicon, zinc oxide (ZnO)).

[0249] Furthermore, a light-emitting element 618 is formed by a first electrode 613, an EL layer 616, and a second electrode 617. The light-emitting element 618 preferably has the structure described in Embodiment 1 or 2. Furthermore, the pixel portion includes a plurality of light-emitting elements, and the light-emitting device of this embodiment may include both light-emitting elements having the structures described in Embodiment 1 or 2 and light-emitting elements having other structures.

[0250] Furthermore, the sealing substrate 604 and the element substrate 610 are bonded together using the sealant 605, and 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. The space 607 is filled with a filler, and an inert gas (nitrogen, argon, etc.), a resin, a dry material, or both a resin and a dry material may be used as the filler.

[0251] Epoxy resin or glass frit is preferably used as the sealant 605. These materials are preferably materials that are as impermeable as possible to moisture and oxygen. Furthermore, as the sealing substrate 604, in addition to glass substrates and quartz substrates, plastic substrates made of FRP (Fiber Reinforced Plastics), PVF (Polyvinyl Fluoride), polyester, or acrylic resin can also be used.

[0252] By the above method, a light-emitting device using the light-emitting element described in Embodiment Mode 1 and Embodiment Mode 2 can be obtained.

[0253] <Structural Example 1 of Light Emitting Device> FIG6 shows a light-emitting device in which a light-emitting element emitting white light and a colored layer (color filter) are formed as an example of the light-emitting device.

[0254] Figure 6A Shown are a substrate 1001, a base insulating film 1002, a gate insulating film 1003, gate electrodes 1006, 1007, 1008, a first interlayer insulating film 1020, a second interlayer insulating film 1021, a peripheral portion 1042, a pixel portion 1040, a driving circuit portion 1041, first electrodes 1024W, 1024R, 1024G, 1024B of the light-emitting element, a partition wall 1026, an EL layer 1028, a second electrode 1029 of the light-emitting element, a sealing substrate 1031, a sealant 1032, a red pixel 1044R, a green pixel 1044G, a blue pixel 1044B, a white pixel 1044W, etc.

[0255] In addition, Figure 6A and Figure 6B In the embodiment, the colored layers (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B) are provided on the transparent substrate 1033. In addition, a black layer (black matrix) 1035 may be provided. The transparent substrate 1033 provided with the colored layers and the black layer is aligned and fixed to the substrate 1001. In addition, the colored layers and the black layer are covered by the covering layer 1036. Figure 6A There is light that does not pass through the colored layers and is transmitted to the outside, and light that passes through the colored layers of each color and is transmitted to the outside. The light that does not pass through the colored layers becomes white light, and the light that passes through the colored layers becomes red light, blue light, and green light, so that an image can be displayed using four color pixels.

[0256] Figure 6B 1034R, the green colored layer 1034G, and the blue colored layer 1034B are formed between the gate insulating film 1003 and the first interlayer insulating film 1020. Figure 6BAs shown, a coloring layer may be provided between the substrate 1001 and the sealing substrate 1031.

[0257] In addition, although the light-emitting device described above has a structure in which light is emitted from the substrate 1001 side where the TFT is formed (bottom emission structure), a light-emitting device can also have a structure in which light is emitted from the sealing substrate 1031 side (top emission structure).

[0258] <Structural Example 2 of Light Emitting Device> Figure 7A and Figure 7B A cross-sectional view of a top-emitting light-emitting device is shown. In this case, a substrate that does not transmit light can be used as substrate 1001. The steps up to the fabrication of the connection electrode connecting the TFT to the anode of the light-emitting element are performed in the same manner as for a bottom-emitting light-emitting device. Next, a third interlayer insulating film 1037 is formed to cover the electrode 1022. This insulating film may also have a planarizing function. The third interlayer insulating film 1037 can be formed using the same material as the second interlayer insulating film 1021 or various other materials.

[0259] Although the lower electrodes 1025W, 1025R, 1025G, and 1025B of the light-emitting element are all anodes here, they may also be cathodes. Figure 7A and Figure 7B In the top-emitting light-emitting device shown, the lower electrodes 1025W, 1025R, 1025G, and 1025B are preferably reflective electrodes. Furthermore, the second electrode 1029 preferably has the functions of both emitting and transmitting light. Furthermore, a microcavity structure is preferably employed 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 described in Embodiments 1 and 2 and has an element structure capable of producing white light emission.

[0260] exist Figure 6A 、 Figure 6B 、 Figure 7A and Figure 7B In the embodiment of the present invention, a structure of an EL layer capable of obtaining white light emission can be realized by using multiple light-emitting layers or multiple light-emitting units. Note that the structure for obtaining white light emission is not limited to this.

[0261] In adopting Figure 7A and Figure 7BIn the case of the top emission structure shown, sealing can be performed using a sealing substrate 1031 provided with colored layers (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B). A black layer (black matrix) 1035 can be provided between pixels on the sealing substrate 1031. The colored layers (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B) and the black layer (black matrix) can also be covered with a cover layer. A light-transmitting substrate is used as the sealing substrate 1031.

[0262] In addition, although Figure 7A The structure of full-color display with three colors of red, green and blue is shown in FIG. Figure 7B As shown, full-color display can also be performed using four colors: red, green, blue, and white. In addition, the structure for performing full-color display is not limited to these structures. For example, full-color display can also be performed using four colors: red, green, blue, and yellow.

[0263] A light-emitting element according to one embodiment of the present invention uses a fluorescent material as a guest material. Because fluorescent materials have a sharper spectrum than phosphorescent materials, they can produce light with high color purity. Therefore, by using this light-emitting element in the light-emitting device described in this embodiment, a light-emitting device with high color reproducibility can be obtained.

[0264] By the above method, a light-emitting device using the light-emitting element described in Embodiment Mode 1 and Embodiment Mode 2 can be obtained.

[0265] In addition, this embodiment mode can be combined with other embodiment modes as appropriate.

[0266] (Implementation 4) In this embodiment, an electronic device and a display device according to one embodiment of the present invention are described.

[0267] According to one embodiment of the present invention, electronic devices and displays having a flat surface, high luminous efficiency, and high reliability can be manufactured. According to one embodiment of the present invention, electronic devices and displays having a curved surface, high luminous efficiency, and high reliability can be manufactured. A light-emitting element according to one embodiment of the present invention can produce light with high color purity. Therefore, by using this light-emitting element in the light-emitting device described in this embodiment, electronic devices and displays with high color reproducibility can be obtained.

[0268] Examples of electronic devices include televisions; desktop or notebook personal computers; displays for computers, etc.; digital cameras; digital video cameras; digital photo frames; mobile phones; portable game consoles; portable information terminals; audio reproducing devices; and large-scale game machines such as pinball machines.

[0269] Figure 8A and Figure 8B The illustrated portable information terminal 900 includes a housing 901 , a housing 902 , a display portion 903 , a hinge portion 905 , and the like.

[0270] The housing 901 and the housing 902 are connected together by a hinge portion 905. The portable information terminal 900 can be opened from a folded state ( Figure 8A ) is converted into Figure 8B As a result, the portability is good when carrying, and the visibility is high when using due to the large display area.

[0271] The portable information terminal 900 is provided with a flexible display portion 903 spanning a housing 901 and a housing 902 connected by a hinge portion 905 .

[0272] The light-emitting device manufactured using one embodiment of the present invention can be used for the display portion 903. Thus, the portable information terminal can be manufactured with high yield.

[0273] The display portion 903 can display at least one of document information, still images, and moving images, etc. When the document information is displayed on the display portion, the portable information terminal 900 can be used as an electronic book reader.

[0274] When the portable information terminal 900 is unfolded, the display portion 903 is maintained in a state with a large curvature radius. For example, the display portion 903 can be maintained so as to include a portion curved with a curvature radius of 1 mm to 50 mm, preferably 5 mm to 30 mm. Pixels are continuously arranged on a portion of the display portion 903, extending across the housing 901 and the housing 902, thereby enabling a curved display.

[0275] The display portion 903 is used as a touch panel and can be operated with a finger, a stylus pen, or the like.

[0276] The display unit 903 is preferably formed of a flexible display. Thus, a continuous display can be provided across the housing 901 and the housing 902. Alternatively, the housing 901 and the housing 902 may each be provided with a display.

[0277] 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 portion 905 preferably has a locking mechanism. For example, the locking angle (at which further opening is impossible) is preferably greater than 90° and less than 180°, and typically can be 90°, 120°, 135°, 150°, or 175°. This improves the convenience, safety, and reliability of the portable information terminal 900.

[0278] When the hinge portion 905 has the above-described locking mechanism, it is possible to suppress application of excessive force to the display portion 903, thereby preventing damage to the display portion 903. Thus, a highly reliable portable information terminal can be realized.

[0279] Housing 901 and housing 902 may also include a power button, operation buttons, an external connection port, a speaker, a microphone, and the like.

[0280] Either housing 901 or housing 902 may be provided with a wireless communication module, and data can be transmitted and received via a computer network such as the Internet, a local area network (LAN), or Wireless Fidelity (Wi-Fi: a registered trademark).

[0281] Figure 8C The illustrated portable information terminal 910 includes a housing 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.

[0282] The light-emitting device manufactured by one embodiment of the present invention can be used for the display portion 912. Thus, the portable information terminal can be manufactured with high yield.

[0283] The portable information terminal 910 includes a touch sensor in the display portion 912. By touching the display portion 912 with a finger or a stylus pen, various operations such as making a call and inputting text can be performed.

[0284] Furthermore, by operating the operation button 913, it is possible to turn the power on and off or switch the type of image displayed on the display portion 912. For example, the e-mail composition screen can be switched to the main menu screen.

[0285] Furthermore, by providing a detection device such as a gyro sensor or an accelerometer within the portable information terminal 910, the orientation (portrait or landscape) of the portable information terminal 910 can be determined, and the screen display orientation of the display unit 912 can be automatically switched. Alternatively, the screen display orientation can be switched by touching the display unit 912, operating the operation button 913, or inputting a voice message using the microphone 916.

[0286] Portable information terminal 910, for example, has one or more functions selected from the group consisting of a telephone, a notebook, and an information reader. Specifically, portable information terminal 910 can be used as a smartphone. Portable information terminal 910 can execute various applications, such as mobile phone use, email, article reading and editing, music playback, video playback, network communication, and computer games.

[0287] Figure 8DThe illustrated camera 920 includes a housing 921 , a display portion 922 , operation buttons 923 , a shutter button 924 , etc. In addition, the camera 920 is equipped with a detachable lens 926 .

[0288] The light-emitting device manufactured by one embodiment of the present invention can be used for the display portion 922. Thus, a highly reliable camera can be manufactured.

[0289] Here, although the camera 920 has a structure in which the lens 926 can be detached from the housing 921 and replaced, the lens 926 and the housing 921 may be formed integrally.

[0290] The camera 920 can capture a still image or a moving image by pressing the shutter button 924. Alternatively, the display portion 922 may have a touch panel function so that the user can capture images by touching the display portion 922.

[0291] In addition, the camera 920 may further include a flash device and a viewfinder that are separately installed. In addition, these components may also be incorporated into the housing 921.

[0292] Figure 9A Schematic diagram showing an example of a sweeping robot.

[0293] The robot vacuum cleaner 5100 includes a display 5101 on the top surface, multiple cameras 5102 on the side, a brush 5103, and operation buttons 5104. Although not shown, the bottom surface of the robot vacuum cleaner 5100 is provided with tires and a suction port. Furthermore, the robot vacuum cleaner 5100 includes various sensors, including infrared sensors, ultrasonic sensors, acceleration sensors, piezoelectric sensors, optical sensors, and gyroscope sensors. Furthermore, the robot vacuum cleaner 5100 includes a wireless communication unit.

[0294] The sweeping robot 5100 can walk automatically, detect garbage 5120, and suck the garbage from the suction port on the bottom.

[0295] In addition, the cleaning robot 5100 can analyze the images captured by the camera 5102 to determine the presence of obstacles such as walls, furniture, or steps. In addition, if the image analysis detects objects such as wiring that may be entangled with the brush 5103, the rotation of the brush 5103 can be stopped.

[0296] The remaining battery power and the amount of garbage sucked in can be displayed on the display 5101. In addition, the walking path of the cleaning robot 5100 can also be displayed on the display 5101. In addition, the display 5101 can be a touch panel, and the operation button 5104 can be displayed on the display 5101.

[0297] The robot vacuum cleaner 5100 can communicate with a portable electronic device 5140, such as a smartphone. Images captured by the camera 5102 can be displayed on the portable electronic device 5140. Therefore, the owner of the robot vacuum cleaner 5100 can also know the status of the room when leaving the house. In addition, the display content of the display 5101 can be confirmed using a portable electronic device such as a smartphone.

[0298] The light-emitting device of one embodiment of the present invention can be used for the display 5101.

[0299] Figure 9B The robot 2100 shown includes a computing device 2110 , an illumination 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 .

[0300] The microphone 2102 has a function of detecting the user's voice and surrounding sounds, etc. The speaker 2104 has a function of emitting sounds. The robot 2100 can communicate with the user using the microphone 2102 and the speaker 2104.

[0301] Display 2105 has the function of displaying various information. Robot 2100 can display user-desired information on display 2105. Display 2105 may be equipped with a touch panel. Display 2105 may be a detachable information terminal. By placing this information terminal at a predetermined location on robot 2100, it can be charged and transmit and receive data.

[0302] The upper camera 2103 and the lower camera 2106 have the function of capturing images of the surrounding environment of the robot 2100. Furthermore, the obstacle sensor 2107 can detect the presence of obstacles in front of the robot 2100 when the robot 2100 moves using the moving mechanism 2108. The robot 2100 can use the upper camera 2103, the lower camera 2106, and the obstacle sensor 2107 to recognize the surrounding environment and move safely.

[0303] The light-emitting device of one embodiment of the present invention can be used for the display 2105 .

[0304] Figure 9C1 is a diagram illustrating an example of a goggle-type display. The goggle-type display includes, for example, a housing 5000, a display portion 5001, a speaker 5003, an LED light 5004, a connection terminal 5006, a sensor 5007 (capable of measuring force, displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, inclination, vibration, odor, or infrared light), a microphone 5008, a second display portion 5002, a support portion 5012, and headphones 5013.

[0305] The light-emitting device of one embodiment of the present invention can be used for the display portion 5001 and the second display portion 5002 .

[0306] Figure 10A and Figure 10B The foldable portable information terminal 5150 is shown. The foldable portable information terminal 5150 includes a housing 5151, a display area 5152, and a bending portion 5153. Figure 10A The portable information terminal 5150 is shown in the unfolded state. Figure 10B The portable information terminal 5150 is shown in a 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 more portable.

[0307] The display area 5152 can be folded in half by the curved portion 5153. The curved portion 5153 is composed of a retractable member and multiple supporting members. When the display area is folded, the retractable member is stretched, and the curved portion 5153 has a curvature radius of 2 mm or more, preferably 5 mm or more.

[0308] The display area 5152 may be a touch panel (input / output device) equipped with a touch sensor (input device). The light-emitting device of one embodiment of the present invention can be used for the display area 5152.

[0309] This embodiment mode can be combined with other embodiment modes as appropriate.

[0310] (Implementation 5) In this embodiment, referring to Figure 11 Examples of cases where the light-emitting element of one embodiment of the present invention is applied to various lighting devices will be described. By using the light-emitting element of one embodiment of the present invention, a lighting device with high luminous efficiency and reliability can be manufactured.

[0311] By forming the light-emitting element of one embodiment of the present invention on a flexible substrate, an electronic device or a lighting device having a light-emitting region on a curved surface can be realized.

[0312] Furthermore, a light-emitting device to which the light-emitting element of one embodiment of the present invention is applied can also be applied to automobile lighting provided on a windshield, ceiling, or the like.

[0313] Figure 11 This is an example of using a light-emitting element in an indoor lighting device 8501. In addition, since the light-emitting element can be large-area, 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. The light-emitting element shown in this embodiment is in the form of a thin film, so the design freedom of the housing is high. Therefore, a lighting device that can correspond to various designs can be formed. In addition, a large lighting device 8503 can also be provided on the wall of the room. In addition, a touch sensor can be provided in the lighting device 8501, the lighting device 8502, and the lighting device 8503 to start or turn off the power.

[0314] Furthermore, by using light-emitting elements on the surface of a table, a lighting device 8504 having the function of a table can be provided. Furthermore, by using light-emitting elements on a part of other furniture, a lighting device having the function of furniture can be provided.

[0315] As described above, by applying the light-emitting device of one embodiment of the present invention, a lighting device and an electronic device can be obtained. Note that the light-emitting device of one embodiment of the present invention is not limited to the light-emitting device described in this embodiment, and can be applied to lighting devices and electronic devices in various fields.

[0316] The structure described in this embodiment can be used in combination with the structures described in other embodiment modes as appropriate. [Example 1]

[0317] In this example, examples of manufacturing Light-Emitting Elements 2 to 5 and Comparative Light-Emitting Element 1, which are light-emitting elements of one embodiment of the present invention, are described. Figure 1A A schematic cross-sectional view of the light-emitting element fabricated in this embodiment is shown, and details of the element structure are shown in Tables 2 and 3. Furthermore, 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 found in Embodiment 1 above.

[0318] [Chemical Formula 19]

[0319] [Table 2]

[0320] [Table 3]

[0321] <Manufacturing of Light-Emitting Element> The following describes the method for manufacturing the light-emitting elements produced in this example. Comparative Light-Emitting Element 1 is a light-emitting element using LiF, a commonly used lithium compound, in the electron injection layer. Light-Emitting Element 2 through Light-Emitting Element 5 are light-emitting elements according to one embodiment of the present invention, using a composite material of an organic compound and a metal having a tridentate or quadridentate interaction with a metal in the electron injection layer.

[0322] <Manufacturing of Comparative Light-Emitting Element 1> As the electrode 101, an ITSO film with a thickness of 110 nm was formed on a glass substrate. In addition, the electrode area of ​​the electrode 101 was 4 mm 2 (2mm×2mm).

[0323] Next, as the hole injection layer 111 , DBT3P-II and molybdenum oxide (MoO 3 ) were co-evaporated on the electrode 101 at a weight ratio (DBT3P-II:MoO 3 ) of 1:0.5 to a thickness of 25 nm.

[0324] Next, PCBBiF was deposited on the hole injection layer 111 to a thickness of 20 nm as the hole transport layer 112 .

[0325] Next, 2mDBTBPDBq-II, PCBBiF, and Ir(dmdppr-dmp)2(dpm) were co-evaporated onto the hole-transport layer 112 to form the light-emitting layer 140. A weight ratio of 2mDBTBPDBq-II:PCBBiF:Ir(dmdppr-dmp)2(dpm) of 0.75:0.25:0.08 was used, resulting in a thickness of 40 nm. In light-emitting layer 140, 2mDBTBPDBq-II and PCBBiF served as host materials, while Ir(dmdppr-dmp)2(dpm) served as the guest material (phosphorescent compound).

[0326] Next, 2mDBTBPDBq-II was vapor-deposited on the light-emitting layer 140 to a thickness of 20 nm as the electron transport layer 118 ( 1 ).

[0327] Next, NBPhen was vapor-deposited to a thickness of 15 nm on the electron transport layer 118 ( 1 ) as the electron transport layer 118 ( 2 ).

[0328] As the electron injection layer 130 , lithium fluoride (LiF) was deposited on the electron transport layer 118 ( 2 ) to a thickness of 1 nm.

[0329] Next, aluminum (Al) was formed to a thickness of 200 nm on the electron injection layer 130 as the electrode 102 .

[0330] Next, heat treatment was performed in the air at 80° C. for 1 hour without sealing. Comparative light-emitting element 1 was obtained through the above steps.

[0331] <Manufacturing of Light-Emitting Elements 2 to 5> Light-emitting elements 2 to 5 differ from 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 comparative light-emitting element 1 .

[0332] <Manufacturing of Light-Emitting Element 2> As the electron injection layer 130 , tPy 2 P and Ag were co-evaporated on the electron transport layer 118 ( 2 ) at a weight ratio (tPy 2 P:Ag) of 1:0.3 to a thickness of 5 nm.

[0333] <Manufacturing of Light-Emitting Element 3> As the electron injection layer 130 , 2Py3Tzn and Cu were co-evaporated on the electron transport layer 118 ( 2 ) at a weight ratio (2Py3Tzn:Cu) of 1:0.3 and a thickness of 5 nm.

[0334] <Manufacturing of Light-Emitting Element 4> As the electron injection layer 130 , Pm 3 Tzn and Cu were co-evaporated on the electron transport layer 118 ( 2 ) at a weight ratio (Pm 3 Tzn:Cu) of 1:0.3 and a thickness of 5 nm.

[0335] <Manufacturing of Light-Emitting Element 5> As the electron injection layer 130 , tPy 2 P and Co were co-evaporated on the electron transport layer 118 ( 2 ) at a weight ratio (tPy 2 P:Co) of 1:0.2 and a thickness of 5 nm.

[0336] <Characteristics of Light-Emitting Element> Next, the device characteristics of the comparative light-emitting elements 1 and 2 to 5 manufactured above were measured. Luminance and CIE chromaticity were measured using a colorimeter (BM-5A, manufactured by Topcon Technohouse). Electroemission spectra were measured using a multi-channel optical spectrum analyzer (PMA-11, manufactured by Hamamatsu Photonics Co., Ltd.).

[0337] 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 15Shown at 2.5 mA / cm 2 Electroemission spectra when current was passed through each light-emitting element at a current density of . Note that the measurement was performed at room temperature.

[0338] Table 4 shows 1000 cd / m 2 The device characteristics of the nearby light-emitting element 1 and the light-emitting elements 2 to 5 are compared.

[0339] [Table 4]

[0340] like Figure 14 As shown in Table 4, Comparative Light-Emitting Element 1 and Light-Emitting Element 2 to Light-Emitting Element 5 all exhibited high luminous efficiency, that is, external quantum efficiencies exceeding 25%. Furthermore, Light-Emitting Element 2 to Light-Emitting Element 5 according to one embodiment of the present invention exhibited high efficiencies comparable to those of Comparative Light-Emitting Element 1, which used LiF, a commonly used material, for its electron injection layer.

[0341] like Figure 13 As shown in Table 4, Comparative Light-Emitting Element 1 and Light-Emitting Element 2 to Light-Emitting Element 5 showed good current-voltage characteristics. Light-Emitting Element 2 to Light-Emitting Element 5 showed current-voltage characteristics equivalent to those of Comparative Light-Emitting Element 1. This indicates that the composite material of a transition metal with a large work function (4.5 eV or greater), such as Cu, Ag, or Co, and an organic compound having a tridentate or quadridentate interaction with the metal has very good electron injection properties equivalent to LiF, a material generally used in electron injection layers.

[0342] like Figure 15 As shown, Comparative Light-Emitting Element 1 and Light-Emitting Element 2 through Light-Emitting Element 5 all exhibited red emission, with peak wavelengths of their electroemission spectra near 619 nm and full widths at half maximum of approximately 58 nm. The resulting electroemission spectra indicate that this emission originates from the guest material, Ir(dmdppr-dmp)2(dpm).

[0343] <Constant Current Drive Test Results of Light-Emitting Element> Next, a driving test was performed on the comparative light-emitting element 1 and the light-emitting elements 2 to 5 in an air atmosphere at a constant current of 1.0 mA. Figure 16 As described above, the comparative light-emitting element 1 and the light-emitting elements 2 to 5 were not sealed. Figure 16It can be seen that the reliability of light-emitting element 2 to light-emitting element 5 is higher than that of comparative light-emitting element 1 under 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. Metals with a small work function have a high reactivity with water, and there is a possibility that moisture will penetrate into the interior of the light-emitting element. Therefore, when the light-emitting element 1 is driven under atmospheric atmosphere, the reliability is reduced 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 that has a low reactivity with water can be used for the electron injection layer. Therefore, as a light-emitting element of one embodiment of the present invention, a light-emitting element can be realized in which moisture is not easily penetrated into the interior of the light-emitting element and which has high reliability when driven under atmospheric atmosphere. In addition, light-emitting element 3 to light-emitting element 5 show high reliability. Therefore, by using a metal with a work function of 4.7 eV or more, such as Cu or Co, a light-emitting element with high reliability can be realized. [Example 2]

[0344] In this example, examples of manufacturing light-emitting elements 7 to 10 and a comparative light-emitting element 6, which are light-emitting elements according to one embodiment of the present invention, are described. Figure 1A A schematic cross-sectional view of a light-emitting element fabricated in this example is shown, and details of the element structure are shown in Tables 5 and 6. Note that the structures and abbreviations of the organic compounds used in this example can refer to those in Embodiment Mode 1 and Example 1 above.

[0345] [Table 5]

[0346] [Table 6]

[0347] <Manufacturing of Light-Emitting Element> The following describes the method for manufacturing the light-emitting elements produced in this example. Comparative Light-Emitting Element 6 is a light-emitting element in which the electrode is in contact with the electron transport layer without forming an electron injection layer. Light-Emitting Element 7 through Light-Emitting Element 10 are light-emitting elements according to one embodiment of the present invention, in which a composite material of an organic compound and a metal having a tridentate or quadridentate interaction with a metal is used in the electron injection layer.

[0348] Manufacturing of Comparative Light-Emitting Element 6 The difference between the comparative light-emitting element 6 and the comparative light-emitting element 1 lies in the process of forming the electron injection layer 130 , and the other processes are the same as those of the comparative light-emitting element 1 .

[0349] The electron injection layer 130 of the comparative light-emitting element 6 was not formed, and Al was deposited to a thickness of 200 nm on the electron transport layer 118 as the electrode 102. That is, in the comparative light-emitting element 6, the electrode 102 was in contact with the electron transport layer 118.

[0350] <Manufacturing of Light-Emitting Elements 7 to 10> The difference between Light-Emitting Elements 7 to 10 and Comparative Light-Emitting Element 1 lies in the process of forming the electron injection layer 130 , and the other processes are the same as those of Comparative Light-Emitting Element 1 .

[0351] <Manufacturing of Light-Emitting Element 7> As the electron injection layer 130 of the light-emitting element 7 , tPy 2 P and Au were co-evaporated on the electron transport layer 118 ( 2 ) at a weight ratio (tPy 2 P:Au) of 1:0.6 to a thickness of 5 nm.

[0352] <Manufacturing of Light-Emitting Element 8> As the electron injection layer 130 of the light-emitting element 8, 2Py3Tzn and Ag were 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.

[0353] <Manufacturing of Light-Emitting Element 9> As the electron injection layer 130 of the light-emitting element 9, tPy2P and Cu were 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.

[0354] <Manufacturing of Light-Emitting Element 10> 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.

[0355] <Characteristics of Light-Emitting Element> 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.

[0356] 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 (maintained at an atmosphere of 23°C). In addition, Figure 20 Shown at 2.5 mA / cm 2 Electroemission spectra when current was passed through each light-emitting element at a current density of . Note that the measurement was performed at room temperature.

[0357] Table 7 shows 1000 cd / m 2The device characteristics of the nearby comparative light-emitting element 6 and the light-emitting elements 7 to 10 are shown.

[0358] [Table 7]

[0359] 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 exhibit 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 exhibits excellent current-voltage characteristics. These results indicate that the electron injection characteristics of Light-emitting Elements 7 to 10 are better than those of Comparative Light-emitting Element 6.

[0360] In the comparative light-emitting element 6, the electrode is in contact with the electron transport layer, and in the light-emitting elements 7 to 10, a metal having a higher work function than Al used for the electrode is used for the electron injection layer. Therefore, focusing on 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 of one embodiment of the present invention, a composite material of an organic compound and a metal having a function of interacting with a metal in a tridentate or quadrudentate manner is used in the electron injection layer, and the SOMO of the composite material is formed in the electron injection layer, so that even if a metal having a function of interacting with a metal in a tridentate or quadrudentate manner is used in the electron injection layer, a good electron injection characteristic can be obtained.

[0361] like Figure 20 As shown, Comparative Light-Emitting Element 6 and Light-Emitting Element 7 through Light-Emitting Element 10 all exhibited red emission, with peak wavelengths of their electroemission spectra near 619 nm and full widths at half maximum of approximately 58 nm. The resulting electroemission spectra indicate that the emission originates from the guest material, Ir(dmdppr-dmp)2(dpm).

[0362] <Constant Current Drive Test Results of Light-Emitting Element> Next, a driving test was performed on the comparative light-emitting element 6 and the light-emitting elements 7 to 10 in an air atmosphere at a constant current of 1.0 mA. Figure 21 The results are shown in FIG. Note that the comparative light-emitting element 6 and the light-emitting elements 7 to 10 were not sealed. Figure 21 It can be seen that the reliability of light emitting elements 7 to 10 is higher than that of comparative light emitting element 6. Figure 18 and Figure 19As shown, the electron injection characteristics of comparative light-emitting element 6 are lower than those of light-emitting elements 7 to 10, and comparative light-emitting element 6 has poor carrier balance, which negatively affects 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, thereby achieving a highly reliable light-emitting element. [Example 3]

[0363] In this example, examples of manufacturing light-emitting elements 12 to 15 and a comparative light-emitting element 11, which are light-emitting elements of one embodiment of the present invention, are described. Figure 1A A schematic cross-sectional view of the light-emitting element fabricated in this example is shown, and details of the element structure are shown in Tables 8 and 9. Furthermore, 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 found in the above examples and Implementation 1.

[0364] [Chemical Formula 20]

[0365] [Table 8]

[0366] [Table 9]

[0367] <Manufacturing of Light-Emitting Element> The following describes the method for manufacturing the light-emitting elements produced in this example. Comparative Light-Emitting Element 11 is a light-emitting element using LiF, a commonly used lithium compound, in the electron injection layer. Light-Emitting Element 12 through Light-Emitting Element 15 are light-emitting elements according to one embodiment of the present invention, each using a composite material of an organic compound and a metal having a tridentate or quadridentate interaction with a metal in the electron injection layer.

[0368] Manufacturing of Comparative Light-Emitting Element 11 As the electrode 101, a 70 nm thick ITSO film was formed on a glass substrate. The electrode 101 had an electrode area of ​​4 mm 2 (2mm×2mm).

[0369] Next, as the hole injection layer 111 , DBT3P-II and molybdenum oxide (MoO 3 ) were co-evaporated on the electrode 101 at a weight ratio (DBT3P-II:MoO 3 ) of 1:0.5 to a thickness of 40 nm.

[0370] Next, PCCP was deposited on the hole injection layer 111 to a thickness of 20 nm as the hole transport layer 112 .

[0371] Next, as the light-emitting layer 140, 9-[3-(4,6-diphenyl-1,3,5-triazine-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviated: mPCCzPTzn-02), PCCP, and GD270 (manufactured by Jilin Aolaide Optoelectronic Materials Co., Ltd.) were co-evaporated on the hole-transporting layer 112 at a weight ratio (mPCCzPTzn:PCCP:GD270) of 0.5:0.5:0.1 to a thickness of 40 nm. Note that in the light-emitting layer 140, mPCCzPTzn and PCCP are host materials, and GD270 is a guest material (phosphorescent compound).

[0372] Next, mPCCzPTzn-02 was vapor-deposited on the light-emitting layer 140 to a thickness of 10 nm as the electron transport layer 118 ( 1 ).

[0373] Next, NBPhen was vapor-deposited to a thickness of 15 nm on the electron transport layer 118 ( 1 ) as the electron transport layer 118 ( 2 ).

[0374] As the electron injection layer 130 , LiF was deposited on the electron transport layer 118 ( 2 ) to a thickness of 1 nm.

[0375] Next, aluminum (Al) was formed to a thickness of 200 nm on the electron injection layer 130 as the electrode 102 .

[0376] Next, heat treatment was performed in the atmosphere at 80° C. for 1 hour without sealing. A comparative light-emitting element 11 was obtained through the above steps.

[0377] <Manufacturing of Light-Emitting Elements 12 to 15> The light-emitting elements 12 to 15 differ from the comparative light-emitting element 11 in the formation process of the electron transport layer 118 ( 2 ) and the electron injection layer 130 , and the other processes are the same as those of the comparative light-emitting element 11 .

[0378] <Manufacturing of Light-Emitting Element 12> 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, tPy2P and Ag were co-deposited on the electron transport layer 118(2) at a weight ratio (tPy2P:Ag) of 1:0.3 to a thickness of 5 nm.

[0379] <Manufacturing of Light-Emitting Element 13> As the electron transport layer 118(2), NBPhen was deposited on the electron transport layer 118(1) to a thickness of 10 nm. Next, as the electron injection layer 130, NBPhen and Ag were co-deposited on the electron transport layer 118(2) at a weight ratio (NBPhen:Ag) of 1:0.3 and a thickness of 5 nm. Furthermore, tPy2P and Au were co-deposited thereon at a weight ratio (tPy2P:Au) of 1:0.6 and a thickness of 5 nm.

[0380] <Manufacturing of Light-Emitting Element 14> 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.

[0381] <Manufacturing of Light-Emitting Element 15> As the electron transport layer 118(2), NBPhen was 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-deposited on the electron transport layer 118(2) at a weight ratio (NBPhen:Cu) of 1:0.2 to a thickness of 5 nm. Furthermore, 2Py3Tzn and Co were co-deposited thereon at a weight ratio (2Py3Tzn:Co) of 1:0.2 to a thickness of 5 nm.

[0382] <Characteristics of Light-Emitting Element> 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.

[0383] 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 spectra when current was passed through each light-emitting element at a current density of . Note that the measurement was performed at room temperature.

[0384] 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.

[0385] [Table 10]

[0386] Depend on Figure 24 As can be seen from Table 10, the comparative 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 23 As shown in Table 10, Comparative Light-Emitting Element 11 and Light-Emitting Element 12 to Light-Emitting Element 15 showed equivalent current-voltage characteristics. These results show that Light-Emitting Element 12 to Light-Emitting Element 15 have electron injection properties equivalent to that of Comparative Light-Emitting Element 11 using generally used LiF in the electron injection layer.

[0387] like Figure 25 As shown, comparative light-emitting element 11 and light-emitting elements 12 to 15 all emitted green light, with peak wavelengths of their electroemission spectra near 520 nm and full widths at half maximum of approximately 63 nm. The obtained electroemission spectra indicate that the emission originates from the guest material GD270.

[0388] <Reliability Evaluation of Light-Emitting Element> Next, a constant temperature and humidity storage test was performed on the comparison light-emitting element 11 and light-emitting elements 12 to 15. Since each light-emitting element is not sealed, the cathode and EL layer of the light-emitting element are exposed to the atmosphere of the test environment. Generally speaking, when moisture penetrates into the light-emitting element, black spots (non-luminous areas in the light-emitting portion) or shrinkage (non-luminous areas at the ends of the light-emitting portion) are generated, which has a negative impact on the reliability of the light-emitting element. Therefore, by performing a constant temperature and humidity storage test, the reliability of the light-emitting element's resistance to moisture can be evaluated.

[0389] After the comparative light-emitting element 11 and light-emitting elements 12 to 15 were placed in a thermostatic chamber maintained at a temperature of 40° C. and a humidity of 90% for 350 hours, the light emission state of each light-emitting element was examined.

[0390] The luminous state was evaluated by estimating the ratio of the luminous area before and after the constant temperature and humidity storage test. Table 11 shows the results.

[0391] [Table 11]

[0392] In Table 11, the luminescent area ratio (%) = luminescent area after the constant temperature and humidity storage test / luminescent area before the constant temperature and humidity test × 100. As can be seen from Table 11, the comparative light-emitting element 11 using LiF, an alkali metal compound, in the electron injection layer deteriorated and became non-luminescent after the storage test. On the other hand, the luminescent area of ​​light-emitting element 12 to light-emitting element 15 of the light-emitting element of one embodiment of the present invention is larger than that of the comparative light-emitting element 11. In other words, the light-emitting element of one embodiment of the present invention has excellent moisture resistance compared with the 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 material with a small work function has a high reactivity with water, and moisture penetrates into the light-emitting element. On the other hand, since the light-emitting element of one embodiment of the present invention can use a metal with low reactivity with water and a large work function, moisture is not easy to penetrate into the light-emitting element. Therefore, a light-emitting element with high moisture resistance can be achieved.

[0393] As described above, the light-emitting element of one embodiment of the present invention has excellent electron injection properties, resulting in a low driving voltage and high luminous efficiency. Furthermore, since materials with a large work function can be used, the light-emitting element has excellent moisture resistance. The structure shown in this embodiment can be used in combination with other embodiments and implementation modes as appropriate. [Example 4]

[0394] In this example, examples of organic compounds that can be used in a light-emitting element according to one embodiment of the present invention and synthesis examples thereof are described.

[0395] <Synthesis of 4'-[4-(10-phenyl-9-anthracenyl)phenyl]-2,2':6',2"-terpyridine (abbreviated as PAtPy) (Structural Formula (200))> 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-anthrylboronic 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 being stirred 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 under a nitrogen stream. Flow for 8 hours. 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 over magnesium sulfate. The mixture of chloroform solution and magnesium sulfate was gravity filtered, and the filtrate was concentrated to obtain a solid. The methanol suspension of the obtained solid was irradiated with ultrasound, and the solid was collected by suction filtration. Furthermore, the solid was recrystallized using toluene to obtain a light red powder of the target with a yield of 1.2 g and a yield of 81%. The following formula (a-1) shows this synthesis scheme.

[0396] [Chemical Formula 21]

[0397] 1.2 g of the resulting pale red powder was purified by sublimation using a gradient sublimation method. During the sublimation purification, PAtPy was heated at 290°C under a pressure of 4.5 Pa and an argon flow rate of 10 mL / min. After sublimation purification, 0.55 g of PAtPy as a pale red powder was obtained with a recovery rate of 47%.

[0398] Using nuclear magnetic resonance spectroscopy ( 1 The light red powder obtained above was measured by H-NMR. The analysis results are shown below.

[0399] 1 H-NMR (CDCl3, 300MHz): δ=7.34-7.40 (m, 6H), 7.49-7.79 (m, 11H), 7.91 (dt, J=1.5Hz, 7.2Hz, 2H), 8.16 (d, J=7.8Hz, 2H), 8.72-8.78 (m, 4H), 8.93 (s, 2H).

[0400] Figure 26A and Figure 26B The obtained light red powder is shown 1 H NMR spectrum. Figure 26B yes Figure 26A The measurement results show that the target compound PAtPy was obtained. [Example 5]

[0401] In this example, examples of organic compounds that can be used in a light-emitting element according to one embodiment of the present invention and synthesis examples thereof are described.

[0402] <Synthesis of 2-[4'-(2,2':6',2"-terpyridin-4'-yl)biphenyl-4-yl]benzoxazole (abbreviated as BOxtPy) (Structural Formula (201))> 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 were placed in a 100 mL three-necked flask. The mixture was degassed while being stirred under reduced pressure, and then the atmosphere in the flask was replaced with nitrogen. 63 mg (55 μmol) of tetrakis(triphenylphosphine)palladium(0) was added to the mixture. Reflux at a temperature of 100 ° C for 5 hours under a nitrogen stream. After reflux, the reaction mixture is cooled to room temperature and the precipitated solid is collected by suction filtration. The chloroform solution of the obtained solid is washed with water, saturated sodium bicarbonate and saturated brine, and dried using magnesium sulfate. The mixture of the obtained chloroform solution and magnesium sulfate is gravity filtered, and the filtrate is concentrated to obtain a solid. The obtained solid is recrystallized using toluene to obtain a light red powder of the target product with a yield of 1.0 g and a yield of 78%. The following formula (b-1) shows this synthesis scheme.

[0403] [Chemical Formula 22]

[0404] 1.0 g of the resulting BOxtPy powder was sublimated and purified using a gradient sublimation method. During the sublimation purification, BOxtPy was heated at 280°C under a pressure of 4.4 Pa and an argon flow rate of 10 mL / min. After the sublimation purification, 0.64 g of a light red BOxtPy powder was obtained with a recovery rate of 63%.

[0405] Using nuclear magnetic resonance spectroscopy ( 1 The light red powder obtained above was measured by H-NMR. The analysis results are shown below.

[0406] 1H-NMR (CDCl3, 300MHz): δ=7.32-7.41 (m, 4H), 7.59-7.65 (m, 1H), 7.78-7.93 (m, 7H), 8.05 (d, J=8.4Hz, 2H), 8.37 (d, J=7.8Hz, 2H), 8.70 (d, J=7.8Hz, 2H), 8.75-8.77 (m, 2H), 8.81 (s, 2H).

[0407] Figure 27A and Figure 27B The obtained light red powder is shown 1 H NMR spectrum. Figure 27B yes Figure 27A The measurement results show that the target compound BOxtPy was obtained. [Example 6]

[0408] In this example, examples of organic compounds that can be used in a light-emitting element according to one embodiment of the present invention and synthesis examples thereof are described.

[0409] <Synthesis of 4'-{4-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]phenyl}-2,2':6',2"-terpyridine (abbreviated as: O11tPy) (Structural Formula (202))> 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. The mixture was degassed while stirring under reduced pressure, 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 a temperature of 100° C. for 9 hours under a nitrogen stream. After stirring, the mixture was cooled to room temperature and the precipitated solid was filtered. The chloroform solution of the obtained solid was washed with water, a saturated aqueous sodium bicarbonate solution and a saturated saline solution, and dried with magnesium sulfate. The mixture was gravity filtered, and the filtrate was concentrated to obtain a solid. The obtained solid was washed with methanol and then recrystallized with toluene / hexane to obtain a white powder of the target product with a yield of 0.72 g and a yield of 51%. The following formula (c-1) shows this synthesis scheme.

[0410] [Chemical Formula 23]

[0411] 0.71 g of the resulting O11tPy powder was purified by sublimation using a gradient sublimation method. During the sublimation purification, the O11tPy was heated at 270°C under a pressure of 4.0 Pa and an argon flow rate of 10 mL / min. After sublimation purification, 0.29 g of white O11tPy powder was obtained with a recovery rate of 41%.

[0412] Using nuclear magnetic resonance spectroscopy ( 1 The white powder obtained above was measured by H-NMR. The analysis results are shown below.

[0413] 1 H-NMR (CDCl3, 300MHz): δ=7.35-7.39 (m, 2H), 7.52-7.58 (m, 3H), 7.79-7.93 (m, 6H), 8.04 (d, J=8.4Hz, 2H), 8.16-8.19 (m, 2H), 8.24 (d, J=8.4Hz, 2H), 8.69 (d, J=7.8Hz, 2H), 8.74-8.76 (m, 2H), 8.80 (s, 2H).

[0414] Figure 28A and Figure 28B The obtained white powder is shown 1 H NMR spectrum. Figure 28B yes Figure 28A The measurement results show that the target compound O11tPy was obtained. [Example 7]

[0415] In this example, examples of organic compounds that can be used in a light-emitting element according to one embodiment of the present invention and synthesis examples thereof are described.

[0416] <Synthesis of 9,9'-[5-(2,2':6',2"-terpyridin-4'-yl)-1,3-phenylene]bis(9H-carbazole) (abbreviated as Cz2PtPy) (Structural Formula (203))> 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 deaerate, 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 a temperature of 80° C. for 7 hours under a stream of nitrogen. After stirring, the aqueous layer of the mixture was extracted with toluene, the extract solution and the organic layer were combined, washed with a saturated aqueous sodium bicarbonate solution and a saturated saline solution, and dried with magnesium sulfate. The mixture was gravity filtered, and the filtrate was concentrated to obtain a solid. The obtained solid was washed with methanol and then recrystallized with toluene to obtain a white powder of the target product with a yield of 1.1 g and a yield of 55%. The following formula (d-1) shows this synthesis scheme.

[0417] [Chemical Formula 24]

[0418] The resulting Cz2PtPy powder (0.83 g) was purified by gradient sublimation. During the sublimation purification, the Cz2PtPy was heated at 290°C under a pressure of 3.2 Pa and an argon flow rate of 5.0 mL / min. After sublimation purification, 0.71 g of white Cz2PtPy powder was obtained with an 86% recovery rate.

[0419] Using nuclear magnetic resonance spectroscopy ( 1 The white powder obtained above was measured by H-NMR. The analysis results are shown below.

[0420] 1 H-NMR (CDCl3, 300MHz): δ=7.31-7.37 (m, 6H), 7.47 (dt, J=0.9Hz, 7.2Hz, 4H), 7.59 (d, J=8.1Hz, 4H), 7.85-7.92(m, 3H), 8.17-8.22(m, 6H), 8.66-8.69(m, 4H), 8.82(s, 2H).

[0421] Figure 29A and Figure 29B The obtained white powder is shown 1 H NMR spectrum. Figure 29B yes Figure 29A The enlarged view of the range from 7.0 ppm to 9.0 ppm in FIG. The measurement results show that the target Cz2PtPy was obtained. [Example 8]

[0422] In this example, examples of organic compounds that can be used in a light-emitting element according to one embodiment of the present invention and synthesis examples thereof are described.

[0423] <Synthesis of 2,4,6-tris(5-phenyl-2-pyrimidin-2-yl)-1,3,5-triazine (abbreviated as PPm3Tzn) (Structural Formula (105))> 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-tetralin are placed in a 50 mL two-necked flask. The mixture is stirred at a temperature of 180° C. for 29 hours and at a temperature of 200° C. for 100 hours under a nitrogen stream. After stirring, the mixture is cooled to room temperature and washed 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 sublimation purification described later, 1 H-NMR analysis revealed a proton ratio of PPm3Tzn:5-phenylpyrimidine-2-carboximidamide = 1:1.7, indicating a mixture of the target compound and the starting material in the brown powder. Furthermore, no signal derived from 2-cyano-5-phenylpyridine was observed.

[0424] [Chemical Formula 25]

[0425] The obtained brown powder (0.79 g) was sublimed and purified by gradient sublimation. During the sublimation purification, the mixture was heated 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 was obtained. 1 In H-NMR, the signal derived from 5-phenylpyrimidine-2-carboximidamide disappeared. This indicates that the target product can be easily purified by sublimation purification.

[0426] Using nuclear magnetic resonance spectroscopy ( 1 The light brown powder obtained above was measured by H-NMR. The analysis results are shown below.

[0427] 1 H-NMR (CDCl3, 300MHz): δ=7.52-7.63 (m, 9H), 7.73 (dd, J=1.5Hz, 7.8Hz, 6H), 9.35 (s, 6H).

[0428] Figure 30A and Figure 30B The obtained light brown powder is shown 1 H NMR spectrum. Figure 30B yes Figure 30A The enlarged view of the range from 7.0 ppm to 9.5 ppm in FIG. The measurement results show that the target PPm3Tzn was obtained. [Example 9]

[0429] As a light-emitting element of one embodiment of the present invention, examples of manufacturing light-emitting elements 16 to 21 , which are one of the following tandem elements, and comparative light-emitting elements 33 and 34 are shown. Figure 31 Schematic cross-sectional views of the light-emitting element manufactured in this embodiment are shown, and Tables 12 to 14 show the details 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 refer to the above-mentioned embodiments and embodiment 1. Note that light-emitting element 16 to light-emitting element 21 are examples of light-emitting elements, in which a plurality of EL layers are connected in series in an element (also referred to as a series element) in which a pair of electrodes are interposed with a charge generation layer, and the charge generation layer ( Figure 31 The electron injection layer ( Figure 31 In the electron injection layer 114), a composite material of an organic compound and a metal having a function of interacting with the metal in a tridentate or quadridentate manner is used.

[0430] [Chemical Formula 26]

[0431] [Table 12]

[0432] [Table 13]

[0433] [Table 14]

[0434] Manufacturing of Light-Emitting Element 16 As the electrode 101, a 110 nm thick ITSO film was formed on a glass substrate. The electrode area was 4 mm 2 (2mm×2mm).

[0435] Next, as the hole injection layer 111 , DBT3P-II and MoO3 were co-evaporated on the electrode 101 at a weight ratio (DBT3P-II:MoO3) of 1:0.5 to a thickness of 25 nm.

[0436] Next, PCBBiF was deposited on the hole injection layer 111 to a thickness of 20 nm as the hole transport layer 112 .

[0437] Next, 2mDBTBPDBq-II, PCBBiF, and Ir(dmdppr-dmp)2(dpm) were co-evaporated onto the hole-transport layer 112 to form the light-emitting layer 170. A weight ratio of 2mDBTBPDBq-II:PCBBiF:Ir(dmdppr-dmp)2(dpm) of 0.75:0.25:0.08 was used to form the co-evaporation layer 170. Note that in the light-emitting layer 170, 2mDBTBPDBq-II and PCBBiF serve as host materials, while Ir(dmdppr-dmp)2(dpm) serves as the guest material (phosphorescent compound).

[0438] Next, as the electron transport layer 113 (1), 2mDBTBPDBq-II was deposited to a thickness of 10 nm on the light emitting layer 170. Next, as the electron transport layer 113 (2), NBPhen was deposited to a thickness of 15 nm.

[0439] As the electron injection layer 114, 2,2'-(pyridine-2,6-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviated as: 2,6(P-Bqn)2Py) and Cu were 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.

[0440] Next, as the charge generation layer 115 , DBT 3 P-II and MoO 3 were co-evaporated on the electron injection layer 114 at a weight ratio (DBT 3 P-II:MoO 3 ) of 1:0.5 to a thickness of 80 nm.

[0441] Next, PCBBiF was deposited on the charge generation layer 115 to a thickness of 20 nm as the hole transport layer 119 .

[0442] 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 (2mDBTBPDBq-II:PCBBiF:Ir(dmdppr-dmp)2(dpm)) of 0.75:0.25:0.08 and a thickness of 40 nm.

[0443] Next, 2mDBTBPDBq-II was deposited to a thickness of 25 nm on the light-emitting layer 140 as the electron transport layer 118 ( 1 ) Next, NBPhen was deposited to a thickness of 10 nm on the electron transport layer 118 ( 2 ) as the electron transport layer 118 ( 1 ) .

[0444] 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.

[0445] Next, Al was deposited to a thickness of 200 nm on the electron injection layer 130 as the electrode 102 .

[0446] Next, in a glove box with a nitrogen atmosphere, a sealing glass substrate was fixed to the glass substrate on which the organic material was formed using an organic EL sealant, 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 sealing glass substrate were bonded together. 2 The film was irradiated with ultraviolet light having a wavelength of 365 nm and heat-treated at 80° C. for 1 hour. The light-emitting element 16 was obtained through the above steps.

[0447] Manufacturing of Light-Emitting Elements 17 to 21, Comparative Light-Emitting Element 33, and Comparative Light-Emitting Element 34 Light-emitting elements 17 to 21, comparative light-emitting elements 33 and 34 were manufactured in the same manner as the light-emitting element 16. The details of the element structures are shown in Tables 12 to 14, and therefore the details of the manufacturing methods are omitted.

[0448] 《Measurement of each light-emitting element》 The device characteristics of the light-emitting elements 16 to 21, the comparative light-emitting element 33, and the comparative light-emitting element 34 manufactured as described above were measured. The brightness and CIE chromaticity were measured using a colorimeter (BM-5A manufactured by Topcon Technohouse). The electroemission spectrum was measured using a multi-channel spectrum analyzer (PMA- 11).

[0449] Figure 32 、 Figure 33 、 Figure 34 and Figure 35 The current efficiency-luminance characteristics, current-voltage characteristics, power efficiency-luminance characteristics, and external quantum efficiency-luminance characteristics of the manufactured light-emitting elements 16 to 21, comparative light-emitting element 33, and comparative light-emitting element 34 are shown respectively. In addition, the measurement of each light-emitting element was performed at room temperature (an atmosphere maintained at 23°C). In addition, Figure 36 Shown at 2.5 mA / cm 2 Electroemission spectra when current was passed through each light-emitting element at a current density of . Note that the measurement was performed at room temperature.

[0450] Table 15 shows 1000 cd / m 2 Element characteristics of the nearby light-emitting elements 16 to 21 , the comparative light-emitting element 33 , and the comparative light-emitting element 34 .

[0451] [Table 15]

[0452] like Figure 36 As shown, the peak wavelengths of the electric field emission spectra of light-emitting elements 16 to 21, comparison light-emitting element 33 and comparison light-emitting element 34 are all around 620 nm. It can be seen that light-emitting elements 16 to 21, comparison light-emitting element 33 and comparison light-emitting element 34 exhibit luminescence originating from Ir(dmdppr-dmp)2(dpm) of the guest material contained in each light-emitting element.

[0453] like Figure 35 As shown in Table 15, all of Light Emitting Elements 16 to 21 showed very high luminous efficiency, which was equivalent to that of Comparative Light Emitting Element 33, that is, the external quantum efficiency exceeded 50%. Figure 32 and Figure 34 As shown, high current efficiency and high power efficiency are demonstrated. On the other hand, the external quantum efficiency of comparative light-emitting element 34 is low, at 27.2%, and does not achieve a sufficiently high efficiency for a tandem element. These results indicate that the electron injection properties from light-emitting element 16 to light-emitting element 21 are equivalent to those of comparative light-emitting element 33, in which Li2O, a commonly used lithium compound, is used in the electron injection layer of the charge generation layer in contact with the EL layer.

[0454] like Figure 33 As shown in Table 15, light-emitting elements 16 to 21 have low driving voltage and good current-voltage characteristics compared with comparative light-emitting elements 33 and comparative light-emitting elements 34. It can be seen that the driving voltage of comparative light-emitting element 34 is very high, and there are problems with the electron injection property from the charge generation layer. From these results, it can be seen that the electron injection property of light-emitting elements 16 to 21 is equal to that of comparative light-emitting element 33 in which Li2O, a generally used Li compound, is used in the electron injection layer of the charge generation layer in contact with the EL layer. Therefore, the composite material of an organic compound and a metal having a function of interacting with a metal in a 3-tooth or 4-tooth manner shows good driving voltage characteristics even when used as an electron injection layer of the charge generation layer in contact with the EL layer in a tandem element.

[0455] <Constant Current Drive Test Results of Light-Emitting Element> Next, a driving test was performed 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 in Figure 2. Figure 52 It can be seen that the reliability of Light-emitting Element 18 and Light-emitting Element 19 is higher than that of Comparative Light-emitting Element 33 and Comparative Light-emitting Element 34. These results show that the reliability of Light-emitting Element 18 and Light-emitting Element 19 is higher than that of Comparative Light-emitting Element 33, which uses Li2O, a commonly used lithium compound, in the electron injection layer in contact with the charge generation layer, and Comparative Light-emitting Element 34, which does not include an electron injection layer in contact with the charge generation layer. Therefore, by using a composite material of an organic compound and a metal having a tridentate or quadridentate function of interacting with a metal as the electron injection layer in contact with the charge generation layer between the EL layers in a tandem element, a highly reliable light-emitting element can be achieved.

[0456] As described above, the light-emitting element of one embodiment of the present invention has excellent electron injection properties, resulting in a low driving voltage and high luminous efficiency. Furthermore, since materials with a large work function can be used, the light-emitting element has excellent moisture resistance and high reliability. The structure shown in this embodiment can be used in combination with other embodiments and implementation modes as appropriate. [Example 10]

[0457] As a light-emitting element of one embodiment of the present invention, examples of manufacturing light-emitting elements 22 to 25 are shown. FIG1 shows a schematic cross-sectional view of a light-emitting element manufactured in this embodiment, and Table 16 shows the details of the element structure. Note that the structures and abbreviations of other compounds can refer to the above-mentioned embodiments and embodiment 1. Note that in light-emitting elements 22 to 25, In, a metal belonging to Group 13, is used as the metal of the composite material of an organic compound and a metal having a function of interacting with a metal in a tridentate or quadridentate manner. [Table 16]

[0458] Manufacturing of Light-Emitting Element 22 The light-emitting element 22 differs from the comparative light-emitting element 1 in the process of forming the electron injection layer 130 , and the other processes are the same as those of the comparative light-emitting element 1 .

[0459] As the electron injection layer 130 of the light-emitting element 22 , tPy 2 P and In were co-evaporated on the electron transport layer 118 ( 2 ) at a weight ratio (tPy 2 P:In) of 1:0.4 and a thickness of 5 nm.

[0460] Manufacturing of Light-Emitting Element 23 The light-emitting element 23 differs from the comparative light-emitting element 1 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 1 .

[0461] As the electron transport layer 118 ( 2 ) of the light-emitting element 23 , NBPhen was deposited to a thickness of 10 nm on the electron transport layer 118 ( 1 ).

[0462] Next, as the electron injection layer 130(1), NBPhen and Ag were co-evaporated on the electron transport layer 118(2) at 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 were co-evaporated on the electron injection layer 130(1) at a weight ratio (2Py3Tzn:In) of 1:0.6 and a thickness of 5 nm.

[0463] <Manufacturing of Light-Emitting Element 24 and Light-Emitting Element 25> The light-emitting element 24 and the light-emitting element 25 differ from the light-emitting element 23 in the process of forming the electron injection layer 130 ( 2 ), and the other processes are the same as those of the light-emitting element 23 .

[0464] <Manufacturing of Light-Emitting Element 24> 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.

[0465] <Manufacturing of Light-Emitting Element 25> 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) in a weight ratio (2,6(NP-PPm)2Py:In) of 1:0.3 and a thickness of 5 nm.

[0466] In Light-Emitting Elements 22 to 25 , 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.

[0467] <Measurement of Each Light-Emitting Element> 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 luminance and CIE chromaticity measurements. A multi-channel optical spectrum analyzer (PMA-11 manufactured by Hamamatsu Photonics Co., Ltd.) was used for electroemission spectrum measurements.

[0468] Figure 37 、 Figure 38 、 Figure 39 and Figure 40 The current efficiency-luminance characteristics, current-voltage characteristics, power efficiency-luminance characteristics, and external quantum efficiency-luminance characteristics of the manufactured light-emitting elements 22 to 25 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 41 Shown at 2.5 mA / cm 2 Electroemission spectra when current was passed through each light-emitting element at a current density of . Note that the measurement was performed at room temperature.

[0469] Table 17 shows 1000 cd / m 2 The device characteristics of the nearby light-emitting elements 22 to 25.

[0470] [Table 17]

[0471] like Figure 41 As shown, the peak wavelengths of the electric field emission spectra of light-emitting elements 22 to 25 are all around 615 nm. It can be seen that light-emitting elements 22 to 25 exhibit luminescence originating from Ir(dmdppr-dmp)2(dpm) of the guest material contained in each light-emitting element.

[0472] like Figure 40 As shown in Table 17, light emitting elements 22 to 25 all showed very high luminous efficiency, that is, external quantum efficiency exceeded 25%. Figure 37 and Figure 39 As shown, high current efficiency and high power efficiency are shown. Therefore, it is known that In is preferably used as the metal for the composite material of the organic compound and metal having the function of interacting with the metal in tridentate or tetradentate.

[0473] In addition, if Figure 38 As shown, light-emitting elements 22 to 25 exhibit good current-voltage characteristics. Therefore, it is understood that In is preferably used as a metal for a composite material of an organic compound and a metal having a function of interacting with a metal in a tridentate or quadridentate manner.

[0474] As described above, the light-emitting element of one embodiment of the present invention has excellent electron injection properties, resulting in a low driving voltage and high luminous efficiency. Furthermore, since materials with a large work function can be used, the light-emitting element has excellent moisture resistance. The structure shown in this embodiment can be used in combination with other embodiments and implementation modes as appropriate. [Example 11]

[0475] An example of manufacturing light-emitting element 26 to light-emitting element 28, which is one of the light-emitting elements of one embodiment of the present invention, is shown. FIG1 shows a schematic cross-sectional view of the light-emitting element manufactured in this embodiment, and Table 18 shows the details of the element structure. In addition, the chemical formula of the organic compound used in this embodiment is shown below. Note that the structures and abbreviations of other compounds can refer to the above-mentioned embodiments and embodiment 1. Note that light-emitting element 26 to light-emitting element 28 are examples of light-emitting elements, in which an organic compound having a triazine skeleton or a bipyridine skeleton is used as an organic compound for a composite material of an organic compound having a function of interacting with a metal at a tridentate or quadridentate and a metal. Note that in this embodiment, a composite material of an organic compound having a function of interacting with a metal at a tridentate or quadridentate and a metal is used for the electron injection layer 130.

[0476] [Chemical Formula 27]

[0477] [Table 18]

[0478] <Manufacturing of Light-Emitting Elements 26 to 28> The light-emitting elements 26 to 28 differ from the comparative light-emitting element 1 in the process of forming the electron injection layer 130 , and the other processes are the same as those of the comparative light-emitting element 1 .

[0479] As the electron injection layer 130 of the light-emitting element 26, PPm3Tzn and Cu were co-evaporated on the electron transport layer 118(2) at a weight ratio (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 considered an organic compound having a pyrimidine skeleton.

[0480] As the electron injection layer 130 of the light-emitting element 27, 2,2'-(2,2'-bipyridine-6,6'-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviated as: 6,6'(P-Bqn)2BPy) and Ag are co-evaporated on the electron transport layer 118(2) in a weight ratio (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.

[0481] As the electron injection layer 130 of the light-emitting element 28, 6,6'(P-Bqn)2BPy and Cu were co-evaporated on the electron transport layer 118(2) at a weight ratio (6,6'(P-Bqn)2BPy:Cu) of 1:0.3 and a thickness of 5 nm.

[0482] In Light-Emitting Elements 26 to 28, 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.

[0483] <Measurement of Each Light-Emitting Element> 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 luminance and CIE chromaticity measurements. A multi-channel optical spectrum analyzer (PMA-11 manufactured by Hamamatsu Photonics Co., Ltd.) was used for electroemission spectrum measurements.

[0484] Figure 42 、 Figure 43 、 Figure 44 and Figure 45 The current efficiency-luminance characteristics, current-voltage characteristics, power efficiency-luminance characteristics, and external quantum efficiency-luminance characteristics of the manufactured light-emitting elements 26 to 28 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 46 Shown at 2.5 mA / cm 2 Electroemission spectra when current was passed through each light-emitting element at a current density of . Note that the measurement was performed at room temperature.

[0485] Table 19 shows 1000 cd / m 2 Element characteristics of the nearby light emitting elements 26 to 28.

[0486] [Table 19]

[0487] like Figure 46 As shown, the peak wavelengths of the electric field emission spectra of light-emitting elements 26 to 28 are all around 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.

[0488] like Figure 45 As shown in Table 19, light emitting elements 26 to 28 all showed very high luminous efficiency, that is, external quantum efficiency exceeded 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 used in a composite material of an organic compound and a metal having a function of interacting with a metal in a tridentate or tetradentate manner, an organic compound having a triazine skeleton (or pyrimidine skeleton) or a bipyridine skeleton (or quinazoline skeleton) is preferably used.

[0489] like Figure 43 As shown, light-emitting elements 26 to 28 exhibit good current-voltage characteristics. Therefore, it is understood that an organic compound having a triazine skeleton (or pyrimidine skeleton) or a bipyridine skeleton (or quinazoline skeleton) is preferably used 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 manner.

[0490] As described above, the light-emitting element of one embodiment of the present invention has excellent electron injection properties, resulting in a low driving voltage and high luminous efficiency. Furthermore, since materials with a large work function can be used, the light-emitting element has excellent moisture resistance. The structure shown in this embodiment can be used in combination with other embodiments and implementation modes as appropriate. [Example 12]

[0491] An example of manufacturing light-emitting element 29 to light-emitting element 32, which is one of the light-emitting elements of one embodiment of the present invention, is shown. FIG1 shows a schematic cross-sectional view of a light-emitting element manufactured in this embodiment, and Table 20 shows the details of the element structure. In addition, the chemical formula of the organic compound used in this embodiment is shown below. Note that the structures and abbreviations of other compounds can refer to the above-mentioned embodiments and embodiment 1. Note that light-emitting element 29 to light-emitting element 32 are examples of light-emitting elements, in which an organic compound having a pyridine skeleton is used as an organic compound for a composite material of an organic compound and a metal having a function of interacting with a metal at a tridentate or quadrudentate. Note that in this embodiment, a composite material of an organic compound and a metal having a function of interacting with a metal at a tridentate or quadrudentate is used for the electron injection layer 130.

[0492] [Table 20]

[0493] <Manufacturing of Light-Emitting Elements 29 to 32> The light-emitting elements 29 to 32 differ from the comparative light-emitting element 1 in the process of forming the electron injection layer 130 , and the other processes are the same as those of the comparative light-emitting element 1 .

[0494] As the electron injection layer 130 of the light-emitting element 29, 2,6(P-Bqn)2Py and Ag were co-evaporated on the electron transport layer 118(2) at 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 considered an organic compound having a quinazoline skeleton.

[0495] 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.

[0496] As the electron injection layer 130 of the light-emitting element 31, 2,6'(NP-PPm)2Py and Ag were co-evaporated on the electron transport layer 118(2) at 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.

[0497] 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.

[0498] <Measurement of Each Light-Emitting Element> 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 luminance and CIE chromaticity measurements. A multi-channel optical spectrum analyzer (PMA-11 manufactured by Hamamatsu Photonics Co., Ltd.) was used for electroemission spectrum measurements.

[0499] Figure 47 、 Figure 48 、 Figure 49 and Figure 50The current efficiency-luminance characteristics, current-voltage characteristics, power efficiency-luminance characteristics, and external quantum efficiency-luminance characteristics of the manufactured light-emitting elements 29 to 32 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 51 Shown at 2.5 mA / cm 2 Electroemission spectra when current was passed through each light-emitting element at a current density of . Note that the measurement was performed at room temperature.

[0500] Table 21 shows 1000 cd / m 2 Element characteristics of the nearby light-emitting elements 29 to 32.

[0501] [Table 21]

[0502] like Figure 51 As shown, the peak wavelengths of the electric field emission spectra of light-emitting elements 29 to 32 are all around 618 nm, from which it can be seen that light-emitting elements 29 to 32 exhibit luminescence originating from Ir(dmdppr-dmp)2(dpm) of the guest material contained in each light-emitting element.

[0503] like Figure 50 As shown in Table 21, light emitting elements 29 to 32 all showed very high luminous efficiency, that is, external quantum efficiency exceeded 28%. Figure 47 and Figure 49 As shown, high current efficiency and high power efficiency are shown. Therefore, it can be seen that as an organic compound used in a composite material of an organic compound and a metal having a function of interacting with a metal in a tridentate or tetradentate manner, an organic compound having a pyridine skeleton (pyrimidine skeleton or quinazoline skeleton) is preferably used.

[0504] like Figure 48 As shown, light-emitting elements 29 to 32 exhibit good current-voltage characteristics. Therefore, it is understood that as an organic compound used in a composite material of an organic compound and a metal having a function of interacting with a metal in a tridentate or tetradentate manner, an organic compound having a triazine skeleton (or a pyrimidine skeleton) or a bipyridine skeleton (or a quinazoline skeleton) is preferably used.

[0505] As described above, the light-emitting element of one embodiment of the present invention has excellent electron injection properties, resulting in a low driving voltage and high luminous efficiency. Furthermore, since materials with a large work function can be used, the light-emitting element has excellent moisture resistance. The structure shown in this embodiment can be used in combination with other embodiments and implementation modes as appropriate. [Explanation of symbols]

[0506] 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 driver circuit, 602: pixel portion, 603: gate side driver circuit, 604: sealing substrate, 60 5: Sealant, 607: Space, 608: Wiring, 610: Element substrate, 611: Switching TFT, 612: Current control TFT, 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, 905: Hinge, 910: Portable information terminal, 911: Housing, 912: Display, 913: Operation button, 914: External connection port, 915: Speaker, 916: Microphone, 917: Camera, 920: Camera, 921: Housing, 922: Display, 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, 1034 B: Coloring layer, 1034G: Coloring layer, 1034R: Coloring layer, 1036: Protective layer, 1037: Interlayer insulating film, 1040: Pixel portion, 1041: Driver circuit portion, 1042: Peripheral portion, 2100: Robot, 2101: Illumination sensor, 2102: Microphone, 2103: Upper camera, 2104: Speaker, 2105: Display, 2106: Lower camera, 2107: Obstacle sensor, 2108: Moving mechanism, 2110: Computing device, 5000: Housing, 5001: Display portion, 5002: Display portion, 5003: Speaker, 5004: LED light, 5005: Operation key, 5006: Connection terminal, 5007: Sensor,5008: Microphone, 5012: Support, 5013: Headphones, 5100: Cleaning robot, 5101: Display, 5102: Camera, 5103: Brush, 5104: Operation button, 5120: Trash, 5140: Portable electronic device, 5150: Portable information terminal, 5151: Housing, 5152: Display area, 5153: Bending portion, 8501: Lighting device, 8502: Lighting device, 8503: Lighting device, 8504: Lighting device,

Claims

1. A light-emitting element, comprising: The light-emitting layer between the anode and cathode; as well as a first layer between the light-emitting layer and the cathode, Wherein, the first layer comprises a first organic compound and a metal, The metal belongs to any one of Groups 3 to 13 of the periodic table, The first organic compound and the metal form a combination of SOMO, Furthermore, the first organic compound is represented by the general formula (G0), Where A 1 and A 3 Each independently represents a substituted or unsubstituted heteroaromatic ring having 1 to 30 carbon atoms, A 1 and A 3 The heteroaromatic ring in each of includes any one of a diazine ring, a triazine ring, a quinoline ring, a quinoxaline ring, a quinazoline ring, a benzoquinazoline ring, an azafluoranthene ring, an imidazole ring, an oxazole ring and an oxadiazole ring, A 2 represents a substituted or unsubstituted heteroaromatic ring having 1 to 30 carbon atoms, and A 2 The heteroaromatic ring is a pyridine ring.

2. A light-emitting element, comprising: The light-emitting layer between the anode and cathode; as well as a first layer between the light-emitting layer and the cathode, Wherein, the first layer comprises a first organic compound and a metal, The metal belongs to any one of Groups 3 to 13 of the periodic table, The first organic compound and the metal form a combination of SOMO, Furthermore, the first organic compound is represented by the general formula (G0), Where A 1 and A 3 Each independently represents a substituted or unsubstituted heteroaromatic ring having 1 to 30 carbon atoms, and A 1 and A 3 The heteroaromatic ring in each of includes any one of a pyridine ring, a diazine 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, A 2 represents a substituted or unsubstituted heteroaromatic ring having 1 to 30 carbon atoms, and A 2 The heteroaromatic ring is any one of a diazine 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.

3. The light-emitting element according to claim 1, wherein A 1 and A 3 The heteroaromatic ring in each of is a heteroaromatic ring represented by any one of (A-2) to (A-15), 4. The light-emitting element according to claim 2, wherein A 1 and A 3 The heteroaromatic ring in each of is a heteroaromatic ring represented by any one of (A-1) to (A-16), 5. A light-emitting element, comprising: The light-emitting layer between the anode and cathode; as well as a first layer between the light-emitting layer and the cathode, Wherein, the first layer comprises a first organic compound and a metal, The metal belongs to any one of Groups 3 to 13 of the periodic table, The first organic compound and the metal form a combination of SOMO, Furthermore, the first organic compound is represented by the general formula (G3-1) or the general formula (G3-3), Where 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 aromatic hydrocarbon group having 6 to 25 carbon atoms, or a substituted or unsubstituted heteroaromatic hydrocarbon group having 3 to 30 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, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms, or a substituted or unsubstituted heteroaromatic hydrocarbon group having 2 to 60 carbon atoms.

6. The light-emitting element according to claim 5, The first organic compound is represented by the general formula (G4-1) or the general formula (G4-3), 7. A light-emitting element, comprising: The light-emitting layer between the anode and cathode; as well as a first layer between the light-emitting layer and the cathode, Wherein, the first layer comprises a first organic compound and a metal, The metal belongs to any one of Groups 3 to 13 of the periodic table, The first organic compound and the metal form a combination of SOMO, Furthermore, the first organic compound is represented by any one of the structural formulas (103), (105), (107), (109), (112), (113), and (200) to (203), 8 . The light-emitting element according to claim 1 , wherein a work function of the metal is 4.0 eV or more and 5.3 eV or less. 9 . The light-emitting element according to claim 1 , wherein the metal is a transition metal. 10 . The light-emitting element according to claim 1 , wherein the metal belongs to Group 11 of the periodic table.

11. The light-emitting element according to any one of claims 1, 2, 5 and 7, further comprising a second layer between the cathode and the first layer. The second layer comprises a second organic compound including an electron-deficient heteroaromatic ring. 12 . The light-emitting element according to claim 11 , wherein the second organic compound has a LUMO energy level lower than an SOMO energy level. 13 . The light-emitting element according to claim 1 , wherein the first layer does not contain an alkali metal and an alkaline earth metal. 14 . The light-emitting element according to claim 1 , wherein the cathode is in contact with the first layer.

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