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

Abstract

To provide a novel organometallic complex having a high quantum yield.SOLUTION: An Ir complex has a structure including a 1H-naphtho[1,2-d]imidazole skeleton as a ligand and represented by general formula (G-1) in the figure. Of N elements included in the 1H-naphtho[1,2-d]imidazole skeleton, the N element that is not bonded to Ir is bonded to a substituted or unsubstituted aryl group.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] One embodiment of the present invention relates to a novel organic compound, in particular, an organometallic complex containing a 1H-naphtho[1,2-d]imidazole skeleton in a ligand, or a light-emitting element, a light-emitting device, an electronic device, and a lighting device each including the organometallic complex.

[0002] Note that one aspect of the present invention is not limited to the above technical fields. One aspect of the present invention relates to an object, a method, or a manufacturing method. In particular, one aspect of the present invention relates to an organic compound, a light-emitting element, a light-emitting device, a lighting device, and a manufacturing method thereof. Another aspect of the present invention relates to a novel synthesis method of an organometallic complex containing a 1H-naphtho[1,2-d]imidazole skeleton in a ligand. Therefore, one aspect of the present invention disclosed in the present specification more specifically can be exemplified by a manufacturing method of a light-emitting element, a light-emitting device, a display device, an electronic device, and a lighting device containing the organometallic complex. [Background technology]

[0003] Light-emitting elements (organic EL elements) that utilize electroluminescence (EL) using organic compounds are becoming more and more practical. The basic structure of these light-emitting elements is a pair of electrodes sandwiching an organic compound layer (EL layer) containing a light-emitting material between them. By applying a voltage to this element, carriers are injected, and the recombination energy of the carriers is utilized to emit light from the light-emitting material.

[0004] Since such light-emitting elements are self-luminous, when used as pixels in a display, they have the advantages of high visibility and no need for a backlight, making them suitable for use as flat panel display elements. Another major advantage of displays using such light-emitting elements is that they can be manufactured to be thin and lightweight. Another characteristic is that they have an extremely fast response speed.

[0005] In addition, these light-emitting devices can have a two-dimensional light-emitting layer that is continuously formed, making it possible to obtain surface light emission. This is a feature that is difficult to obtain with point light sources such as incandescent light bulbs and LEDs, or linear light sources such as fluorescent lamps. Furthermore, by selecting the appropriate material, the light emitted from organic compounds can be made to not contain ultraviolet light, making them highly useful as surface light sources that can be applied to lighting, etc.

[0006] As such, displays and lighting devices using organic EL elements are suitable for various electronic devices, and therefore research and development is being conducted to seek light-emitting elements with better efficiency and element life. In recent years, phosphorescent light-emitting elements are capable of achieving higher luminous efficiency than fluorescent light-emitting elements, and therefore phosphorescent materials have been actively developed (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2013-147496 A Summary of the Invention [Problem to be solved by the invention]

[0008] As reported in the above-mentioned Patent Document 1, the development of phosphorescent materials exhibiting excellent properties has progressed, but there is a demand for the development of new materials exhibiting even better properties, particularly blue and green phosphorescent materials with high efficiency and high reliability.

[0009] In view of the above, an object of one embodiment of the present invention is to provide a novel organometallic complex. Alternatively, an object of one embodiment of the present invention is to provide a novel organometallic complex including a 1H-naphtho[1,2-d]imidazole skeleton. Alternatively, an object of one embodiment of the present invention is to provide an organometallic complex having high quantum yield. Alternatively, an object of one embodiment of the present invention is to provide a light-emitting element with high emission efficiency. Alternatively, an object of one embodiment of the present invention is to provide a light-emitting element with high lifetime. Alternatively, an object of one embodiment of the present invention is to provide a light-emitting element with high color purity. Alternatively, an object of one embodiment of the present invention is to provide a light-emitting element with low driving voltage.

[0010] Another object of another embodiment of the present invention is to provide a light-emitting element, a light-emitting device, and an electronic device with high reliability, or to provide a light-emitting element, a light-emitting device, and an electronic device with low power consumption.

[0011] Note that the description of these problems does not preclude the existence of other problems. Note that one embodiment of the present invention does not necessarily have to solve all of these problems. Note that problems other than these will become apparent from the description of the specification, drawings, claims, etc., and it is possible to extract problems other than these from the description of the specification, drawings, claims, etc. [Means for solving the problem]

[0012] One embodiment of the present invention is an organometallic complex having a structure represented by the following general formula (G-1), which contains a 1H-naphtho[1,2-d]imidazole skeleton in a ligand.

[0013] [ka]

[0014] In general formula (G-1), R 1 ~R 10each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 25 carbon atoms, or an electron-withdrawing group, and Ar represents a substituted or unsubstituted aryl group having 6 to 25 carbon atoms.

[0015] Another embodiment of the present invention is an organometallic complex having a structure represented by the following general formula (G-2).

[0016] [ka]

[0017] In general formula (G-2), R 1 ~R 15 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 25 carbon atoms, or an electron-withdrawing group.

[0018] Another embodiment of the present invention is an organometallic complex having a structure represented by the following general formula (G-3).

[0019] [ka]

[0020] In general formula (G-3), R 11 , R 13 and R 15 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 25 carbon atoms, or an electron-withdrawing group.

[0021] Another embodiment of the present invention is an organometallic complex having a structure represented by the following general formula (G-4).

[0022] [ka]

[0023] In general formula (G-4), R 13 represents hydrogen or an electron-withdrawing group.

[0024] Another embodiment of the present invention is an organometallic complex having a structure represented by the following general formula (G-5).

[0025] [ka]

[0026] In general formula (G-5), R 15 represents hydrogen, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 25 carbon atoms.

[0027] In the above structure, general formula (G-1) is preferably represented by general formula (G-6).

[0028] [ka]

[0029] In the above structure, general formula (G-2) is preferably represented by general formula (G-7).

[0030] [ka]

[0031] In the above structure, general formula (G-3) is preferably represented by general formula (G-8).

[0032] [ka]

[0033] In the above structure, general formula (G-4) is preferably represented by general formula (G-9).

[0034] [ka]

[0035] In the above structure, general formula (G-5) is preferably represented by general formula (G-10).

[0036] [ka]

[0037] In the above structure, general formula (G-1) is preferably represented by general formula (G-11).

[0038] [ka]

[0039] In formula (G-11), L represents a monoanionic ligand; n represents 1 or 2.

[0040] In the above structure, general formula (G-2) is preferably represented by general formula (G-12).

[0041] [ka]

[0042] In formula (G-12), L represents a monoanionic ligand; n represents 1 or 2.

[0043] In the above structure, general formula (G-3) is preferably represented by general formula (G-13).

[0044] [ka]

[0045] In formula (G-13), L represents a monoanionic ligand; n represents 1 or 2.

[0046] In the above structure, general formula (G-4) is preferably represented by general formula (G-14).

[0047] [ka]

[0048] In formula (G-14), L represents a monoanionic ligand; n represents 1 or 2.

[0049] In the above structure, general formula (G-5) is preferably represented by general formula (G-15).

[0050] [ka]

[0051] In formula (G-15), L represents a monoanionic ligand; n represents 1 or 2.

[0052] In the general formulae (G-3), (G-8) and (G-13), R 11 and R 15 are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, or a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms; R 13 is preferably hydrogen or an electron withdrawing group.

[0053] In the above structure, the electron-withdrawing group is preferably any one of a halogeno group, a cyano group, and a trifluoromethyl group.

[0054] In the above structure, the alkyl group is preferably a branched alkyl group having 3 to 6 carbon atoms.

[0055] In the above-mentioned configuration, the monoanionic ligand is preferably a monoanionic bidentate chelate ligand having a β-diketone structure, a monoanionic bidentate chelate ligand having a carboxyl group, a monoanionic bidentate chelate ligand having a phenolic hydroxyl group, a monoanionic bidentate chelate ligand in which both of the two coordinating elements are nitrogen, or a bidentate ligand that forms a metal-carbon bond with iridium by cyclometallation.

[0056] In the above structure, the monoanionic ligand is preferably any one of the following general formulas (L1) to (L9).

[0057] [ka]

[0058] In general formulas (L1) to (L9), R 21 ~R 86 each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a halogeno group, a vinyl group, a cyano group, a substituted or unsubstituted haloalkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 6 carbon atoms, a substituted or unsubstituted alkylthio group having 1 to 6 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 13 carbon atoms. 1 or A 13 are independently sp bonds to nitrogen or hydrogen 2 Hybridized carbon or substituted sp 2 It represents a hybrid carbon, and the substituent represents any one of an alkyl group having 1 to 6 carbon atoms, a halogeno group, a haloalkyl group having 1 to 6 carbon atoms, or a phenyl group.

[0059] Another embodiment of the present invention is an organic compound represented by any one of the following structural formulas (100) to (103).

[0060] [ka]

[0061] Another embodiment of the present invention is a light-emitting element having an EL layer between a pair of electrodes, the EL layer containing any of the organic compounds described above. The organic compound is preferably contained in a light-emitting layer in the EL layer.

[0062] In addition, the light-emitting element in each of the above structures has an EL layer between an anode and a cathode. The EL layer preferably has at least a light-emitting layer. The EL layer may further include a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, or other functional layers.

[0063] Another embodiment of the present invention is a display device having a light-emitting element having any of the above structures and at least one of a color filter or a transistor. Another embodiment of the present invention is an electronic device having the display device and at least one of a housing or a touch sensor. Another embodiment of the present invention is a lighting device having a light-emitting element having any of the above structures and at least one of a housing or a touch sensor. Another embodiment of the present invention includes not only a light-emitting device having a light-emitting element, but also an electronic 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). Another embodiment of the present invention is a display module in which a connector, for example, an FPC (Flexible Printed Circuit) or a TCP (Tape Carrier Package) is attached to a light-emitting element, a display module in which a printed wiring board is provided at the end of a TCP, or a display module in which an IC (Integrated Circuit) is directly mounted on a light-emitting element by a COG (Chip On Glass) method. Effect of the Invention

[0064] According to one embodiment of the present invention, a novel organometallic complex can be provided. According to one embodiment of the present invention, a novel organometallic complex including a 1H-naphtho[1,2-d]imidazole skeleton can be provided. According to one embodiment of the present invention, an organometallic complex having high quantum yield can be provided. According to one embodiment of the present invention, a light-emitting element having high emission efficiency can be provided. According to one embodiment of the present invention, a light-emitting element having high lifetime can be provided. According to one embodiment of the present invention, a light-emitting element having high color purity can be provided. According to one embodiment of the present invention, a light-emitting element having low driving voltage can be provided.

[0065] According to another embodiment of the present invention, a light-emitting element, a light-emitting device, and an electronic device with high reliability can be provided. According to another embodiment of the present invention, a light-emitting element, a light-emitting device, and an electronic device with low power consumption can be provided.

[0066] Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. Note that effects other than these are self-evident from the description in the specification, drawings, claims, etc., and it is possible to extract effects other than these from the description in the specification, drawings, claims, etc. [Brief description of the drawings]

[0067] [Figure 1] 1A and 1B are schematic diagrams of a light-emitting element according to one embodiment of the present invention, and Fig. 1C is a diagram illustrating the correlation of energy levels of a light-emitting element according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram of a light-emitting device according to one embodiment of the present invention. [Diagram 3] 3A and 3B are conceptual diagrams of an active matrix light-emitting device according to one embodiment of the present invention. [Figure 4] 4A and 4B are conceptual diagrams of an active matrix light-emitting device according to one embodiment of the present invention. [Diagram 5] FIG. 5 is a conceptual diagram of an active matrix light-emitting device according to one embodiment of the present invention. [Figure 6] 6A to 6D each illustrate an electronic device according to one embodiment of the present invention. [Figure 7] 7A to 7E each illustrate an electronic device according to one embodiment of the present invention. [Figure 8] 8A to 8C are diagrams illustrating electronic devices according to one embodiment of the present invention. [Figure 9] 9A and 9B are diagrams illustrating electronic devices according to one embodiment of the present invention. [Figure 10] 10A to 10C are diagrams illustrating a lighting device according to one embodiment of the present invention. [Figure 11] FIG. 11 is a diagram illustrating a lighting device according to one embodiment of the present invention. [Figure 12] FIG. 12 is a diagram illustrating an NMR chart of a compound according to an example. [Figure 13] FIG. 13 is a diagram illustrating the absorption spectrum and emission spectrum of a compound according to an example. [Figure 14] FIG. 14 is a diagram illustrating an NMR chart of a compound according to an example. [Figure 15] FIG. 15 is a diagram illustrating the absorption spectrum and emission spectrum of a compound according to an example. [Figure 16] FIG. 16 is a diagram illustrating the absorption spectrum and emission spectrum of a compound according to an example. [Figure 17] FIG. 17 is a diagram illustrating an NMR chart of a compound according to an example. [Figure 18] FIG. 18 is a diagram illustrating the absorption spectrum and emission spectrum of a compound according to an example. [Figure 19] FIG. 19 is a diagram illustrating the current efficiency-luminance characteristics of a light-emitting element according to an example. [Figure 20] FIG. 20 is a diagram illustrating the current density-voltage characteristics of the light-emitting element according to the example. [Figure 21] FIG. 21 is a diagram illustrating the external quantum efficiency-luminance characteristics of a light-emitting element according to an example. [Figure 22] FIG. 22 is a diagram illustrating an emission spectrum of a light-emitting element according to an example. [Figure 23] FIG. 23 is a diagram illustrating the current efficiency-luminance characteristics of a light-emitting element according to an example. [Figure 24] FIG. 24 is a diagram illustrating the current density-voltage characteristics of the light-emitting element according to the example. [Diagram 25] FIG. 25 is a diagram illustrating the external quantum efficiency-luminance characteristics of a light-emitting element according to an example. [Figure 26] FIG. 26 is a diagram illustrating an emission spectrum of a light-emitting element according to an example. [Figure 27] FIG. 27 is a diagram illustrating the results of a reliability test of a light-emitting element according to an example. [Figure 28] FIG. 28 is a diagram illustrating the current efficiency-luminance characteristics of a light-emitting element according to an example. [Figure 29] FIG. 29 is a diagram illustrating the current density-voltage characteristics of a light-emitting element according to an example. [Diagram 30] FIG. 30 is a diagram illustrating the external quantum efficiency-luminance characteristics of a light-emitting element according to an example. [Diagram 31] FIG. 31 is a diagram illustrating an emission spectrum of a light-emitting element according to an example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0068] Hereinafter, the embodiments of the present invention will be described. However, it will be easily understood by those skilled in the art that the present invention can be implemented in many different forms, and that the form and details can be modified in various ways without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the description of the present embodiment.

[0069] In the drawings described in this specification, the size and thickness of the anode, EL layer, intermediate layer, cathode, etc. may be exaggerated for clarity of explanation. Therefore, the size of each component is not necessarily limited to the size, and the relative size between each component is not necessarily limited to the size of each component.

[0070] In addition, in this specification, ordinal numbers such as first, second, third, etc. are used for convenience and do not indicate the order of steps or the hierarchical relationship. Therefore, for example, "first" can be appropriately replaced with "second" or "third" for explanation. In addition, the ordinal numbers described in this specification and the like may not match the ordinal numbers used to specify one embodiment of the present invention.

[0071] In the configuration of the present invention described in this specification, the same reference numerals are used in different drawings for the same parts or parts having similar functions, and repeated explanations are omitted. In addition, when referring to parts having similar functions, the same hatch pattern may be used and no particular reference numeral may be used.

[0072] In addition, the words "film" and "layer" can be interchangeable depending on the case or situation. For example, the term "conductive layer" can be changed to the term "conductive film". Or, for example, the term "insulating film" can be changed to the term "insulating layer".

[0073] (Embodiment 1) In this embodiment, an organometallic complex of one embodiment of the present invention will be described below.

[0074] An organometallic complex of one embodiment of the present invention has a structure represented by the following general formula (G-1).

[0075] [ka]

[0076] In general formula (G-1), R 1 ~R 10 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 25 carbon atoms, or an electron-withdrawing group, and Ar represents a substituted or unsubstituted aryl group having 6 to 25 carbon atoms.

[0077] The organometallic complex of one embodiment of the present invention has a 1H-naphtho[1,2-d]imidazole skeleton as a ligand. With this structure, when the organometallic complex is used in a light-emitting element, a light-emitting element with high emission efficiency and / or reliability can be obtained.

[0078] The ligand in the organometallic complex of one embodiment of the present invention has a structure in which a benzene ring is further condensed to the benzene ring in the benzimidazole skeleton. With this structure, the stability of the molecule is improved, and a light-emitting element with high reliability can be obtained. In addition, an organometallic complex with high emission quantum yield can be obtained.

[0079] In addition, by bonding a substituted or unsubstituted aryl group having 6 to 25 carbon atoms to the 1-position of the 1H-naphtho[1,2-d]imidazole skeleton, the stability and sublimability of the molecule are improved compared to the case where hydrogen or an alkyl group is bonded to the 1-position. Therefore, a light-emitting element with high reliability can be obtained. In addition, when an organic EL element is manufactured by a vacuum deposition method, the organic compound of one embodiment of the present invention can be suitably used.

[0080] <Condensation position of imidazole skeleton and naphthalene skeleton> The 1H-naphtho[1,2-d]imidazole skeleton of the organometallic complex of one embodiment of the present invention can be regarded as a structure in which a naphthalene skeleton is condensed to an imidazole skeleton. In this case, when the naphthalene skeleton is condensed at the a-position of the imidazole skeleton, an Ir complex having a structure represented by the following general formula (I-1) is considered as an example.

[0081] [ka]

[0082] In general formula (I-1), R 1 ~R 7 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 25 carbon atoms.

[0083] The structure shown in general formula (I-1) has a structure in which an imidazole skeleton bonded to Ir and a benzene skeleton bonded to Ir are condensed with each other. This structure tends not to have a high quantum yield. In addition, since the imidazole skeleton bonded to Ir and the benzene skeleton bonded to Ir are condensed, it is expected that light will be emitted at a longer wavelength than when they are not condensed. Therefore, it is expected that this skeleton is not suitable for blue and green phosphorescent materials, which are particularly in demand for development.

[0084] On the other hand, the 1H-naphtho[1,2-d]imidazole skeleton of the organometallic complex of one embodiment of the present invention has a structure in which a naphthalene skeleton is condensed at the d-position of the imidazole skeleton. Here, when a naphthalene skeleton is condensed at the d-position of the imidazole skeleton, a 1H-naphtho[1,2-d]imidazole skeleton or a 1H-naphtho[2,1-d]imidazole skeleton is considered depending on the difference in the condensation position. The influence of the difference in these condensed carbons on the quantum yield was considered by molecular orbital calculation.

[0085] <Net charge calculation example> In this calculation example, a calculation example of the lowest triplet excited state (T1 state) of Compound-A, which is a model of an organometallic complex having a 1H-naphtho[1,2-d]imidazole skeleton according to one embodiment of the present invention, and Compound-B, which is a model of an organometallic complex having a 1H-naphtho[2,1-d]imidazole skeleton for comparison, is specifically illustrated. The structures of Compound-A and Compound-B are shown below. In Compound-A, the benzene ring of a shown in the structural formula is condensed on the opposite side to Ir as viewed from N (nitrogen) bonded to Ir. On the other hand, in Compound-B, the benzene ring of b shown in the structural formula is condensed on the same side as Ir as viewed from N (nitrogen) bonded to Ir. When the 1H-naphtho[2,1-d]imidazole skeleton is used as a ligand of the Ir complex, it has a structure in which the benzene ring is condensed in the same direction as Compound-B.

[0086] [ka]

[0087] The Gaussian09 program was used for molecular orbital calculations. The functional used was B3PW91, and geometry optimization and vibration calculations were performed. The basis set used was LANL2DZ for Ir and 6-311G for the other elements.

[0088] The net charge on Ir in the calculated optimized structure was 0.30 for Compound-A, whereas it was calculated to be 0.20 for Compound-B.

[0089] The results showed that the net charge of Ir in Compound-A was significantly higher than that in Compound-B. Metal-Ligand Charge Transfer (MLCT) is a mechanism that transfers charge between the 5d orbital of Ir and the π orbital of the ligand. *is a transition contributed by. One of the factors of high MLCT property is that the net charge of Ir is high in the excited state. Therefore, it was found that Compound-A, which is a model of an organometallic complex of one embodiment of the present invention, has higher MLCT property in the excited state than Compound-B. It is known that there is a correlation between MLCT property and quantum yield of phosphorescent materials, and it is expected that the emission quantum yield is high when the MLCT property is high. Therefore, it was found that the organic compound of one embodiment of the present invention has a high emission quantum yield.

[0090] In Compound-B, the benzene ring indicated by b in the structural formula is oriented in such a way that it creates steric hindrance with Ir. Therefore, it is expected that the bond distance between Ir and the N (nitrogen) of the imidazole skeleton in Compound-B will be longer. Therefore, as mentioned above, it is considered that the net charge on Ir is smaller in Compound-B. The Ir complex with a 1H-naphtho[2,1-d]imidazole skeleton also has a benzene ring indicated by b in the structural formula, so it is considered that it has a small net charge like Compound-B. On the other hand, the benzene ring indicated by a in the structural formula of Compound-A does not create steric hindrance with Ir. Therefore, it is considered that the result shows a larger net charge than Compound-B.

[0091] From the above, when considering an organometallic complex having a structure in which a naphthalene skeleton is condensed with an imidazole skeleton, it is possible to obtain an organometallic complex with a good luminescence quantum yield by using a 1H-naphtho[1,2-d]imidazole skeleton.

[0092] The aryl group having 6 to 25 carbon atoms is preferably a substituted or unsubstituted phenyl group. With this structure, the organometallic complex of one embodiment of the present invention can be synthesized inexpensively and easily. Therefore, it is preferable that General Formula (G-1) has a structure represented by the following General Formula (G-2).

[0093] [ka]

[0094] In general formula (G-2), R 1 ~R 15 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 25 carbon atoms, or an electron-withdrawing group.

[0095] Further, an organometallic complex of one embodiment of the present invention has a structure represented by the following general formula (G-3).

[0096] [ka]

[0097] In general formula (G-3), R 11 , R 13 and R 15 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 25 carbon atoms, or an electron-withdrawing group.

[0098] In general formulae (G-2) and (G-3), R 11 and R 15 At least one of R is preferably an alkyl group having 1 to 6 carbon atoms. This structure allows the material to have good sublimability, and therefore the material usage efficiency can be improved when a light-emitting element is fabricated by a vacuum deposition method. 11 and R 15 The phenyl group to which R is bonded is 11 and R 15When at least one of the alkyl groups is an alkyl group having 1 to 6 carbon atoms, the dihedral angle between the phenyl group and the 1H-naphtho[1,2-d]imidazole skeleton becomes large due to the steric hindrance of the alkyl group. Therefore, the conjugation between the phenyl group and the 1H-naphtho[1,2-d]imidazole skeleton is less likely to spread, so that the emission wavelength can be shortened. In addition, it is more preferable that the alkyl group is a branched alkyl group having 3 to 7 carbon atoms. By using a branched alkyl group, the above-mentioned effect can be more easily obtained. Examples of the branched alkyl group include an isopropyl group, an isobutyl group, and a tertiary butyl group.

[0099] Therefore, an organometallic complex of one embodiment of the present invention has a structure represented by the following general formula (G-4).

[0100] [ka]

[0101] In general formula (G-4), R 13 represents hydrogen or an electron-withdrawing group.

[0102] In general formula (G-4), R 13 It is preferable that R is hydrogen since it is easy to synthesize. 13 When is an electron-withdrawing group, the LUMO (Lowest Unoccupied Molecular Orbital) level and the HOMO (Highest Occupied Molecular Orbital) level of the organometallic complex can be lowered. Therefore, when the organometallic complex is used in a light-emitting element, the electron injection property can be improved while maintaining the hole injection property, and the luminous efficiency can be improved. In addition, the CT (Charge Transfer) property can be expected to be improved, and the spectral width can be expected to be widened. Therefore, a light-emitting element with high color rendering properties can be manufactured.

[0103] Further, an organometallic complex of one embodiment of the present invention is represented by the following general formula (G-5).

[0104] [ka]

[0105] In general formula (G-5), R 15 represents hydrogen, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 25 carbon atoms.

[0106] As described above, by introducing a cyano group, which is an electron-withdrawing group, into the 4-position of the phenyl group bonded to the 1-position of 1H-naphtho[1,2-d]imidazole, a light-emitting device with good luminous efficiency and high color rendering properties can be fabricated.

[0107] Further, an organometallic complex of one embodiment of the present invention is represented by the following general formula (G-6).

[0108] [ka]

[0109] In general formula (G-6), R 1 ~R 10 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 25 carbon atoms, or an electron-withdrawing group, and Ar represents a substituted or unsubstituted aryl group having 6 to 25 carbon atoms.

[0110] The organometallic complex represented by general formula (G-6) is a tris-form of the organometallic complex represented by general formula (G-1), in which all three ligands of the organometallic complex are the same. The tris-form organometallic complex is preferred because it has good luminous efficiency and reliability.

[0111] Further, an organometallic complex of one embodiment of the present invention is represented by the following general formula (G-7).

[0112] [ka]

[0113] In general formula (G-7), R 1 ~R 15 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 25 carbon atoms, or an electron-withdrawing group.

[0114] The organometallic complex represented by general formula (G-7) is a tris-form of the organometallic complex represented by general formula (G-2), in which all three ligands of the organometallic complex are the same. The tris-form organometallic complex is preferred because it has good luminous efficiency and reliability.

[0115] Further, an organometallic complex of one embodiment of the present invention is represented by the following general formula (G-8).

[0116] [ka]

[0117] In general formula (G-8), R 11 , R 13 and R 15 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 25 carbon atoms, or an electron-withdrawing group.

[0118] The organometallic complex represented by general formula (G-8) is a tris-form of the organometallic complex represented by general formula (G-3), in which all three ligands of the organometallic complex are the same. The tris-form organometallic complex is preferred because it has good luminous efficiency and reliability.

[0119] Further, an organometallic complex of one embodiment of the present invention is represented by the following general formula (G-9).

[0120] [ka]

[0121] In general formula (G-9), R 13 represents hydrogen or an electron-withdrawing group.

[0122] The organometallic complex represented by general formula (G-9) is a tris-form of the organometallic complex represented by general formula (G-4), in which all three ligands of the organometallic complex are the same. The tris-form organometallic complex is preferred because it has good luminous efficiency and reliability.

[0123] Further, an organometallic complex of one embodiment of the present invention is represented by the following general formula (G-10).

[0124] [ka]

[0125] In general formula (G-10), R 15 represents hydrogen, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 25 carbon atoms.

[0126] The organometallic complex represented by general formula (G-10) is a tris-form of the organometallic complex represented by general formula (G-5), in which all three ligands of the organometallic complex are the same. The tris-form organometallic complex is preferred because it has good luminous efficiency and reliability.

[0127] Further, an organometallic complex of one embodiment of the present invention is represented by the following general formula (G-11).

[0128] [ka]

[0129] In general formula (G-11), R 1 ~R 10 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 25 carbon atoms, or an electron-withdrawing group; Ar represents a substituted or unsubstituted aryl group having 6 to 25 carbon atoms; L represents a monoanionic ligand; and n represents 1 or 2.

[0130] The organometallic complex represented by the general formula (G-11) is an organometallic complex having two or more ligands among the organometallic complexes represented by the general formula (G-1), and is a hetero-compound. The hetero-compound organometallic complex is preferable because the emission color and sublimation property can be adjusted by selecting the combination of ligands.

[0131] Further, an organometallic complex of one embodiment of the present invention is represented by the following general formula (G-12).

[0132] [ka]

[0133] In general formula (G-12), R 1 ~R 15 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 25 carbon atoms, or an electron-withdrawing group; L represents a monoanionic ligand; and n represents 1 or 2.

[0134] The organometallic complex represented by the general formula (G-12) is a hetero-compound, which is a metal complex having two or more kinds of ligands among the organometallic complexes represented by the general formula (G-2). The hetero-compound organometallic complex is preferable because the emission color and sublimation property can be adjusted by selecting the combination of ligands.

[0135] Further, an organometallic complex of one embodiment of the present invention is represented by the following general formula (G-13).

[0136] [ka]

[0137] In general formula (G-13), R 11 , R 13 and R 15 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 25 carbon atoms, or an electron-withdrawing group; L represents a monoanionic ligand; and n represents 1 or 2.

[0138] The organometallic complex represented by the general formula (G-13) is a hetero-compound, which is a metal complex having two or more kinds of ligands among the organometallic complexes represented by the general formula (G-3). The hetero-compound organometallic complex is preferable because the emission color and sublimation property can be adjusted by selecting the combination of ligands.

[0139] Further, an organometallic complex of one embodiment of the present invention is represented by the following general formula (G-14).

[0140] [ka]

[0141] In general formula (G-14), R 13 represents hydrogen or an electron-withdrawing group, L represents a monoanionic ligand, and n represents 1 or 2.

[0142] The organometallic complex represented by the general formula (G-14) is a hetero-compound, which is a metal complex having two or more kinds of ligands among the organometallic complexes represented by the general formula (G-4). The hetero-compound organometallic complex is preferable because the emission color and sublimation property can be adjusted by selecting the combination of ligands.

[0143] Further, an organometallic complex of one embodiment of the present invention is represented by the following general formula (G-15).

[0144] [ka]

[0145] In general formula (G-15), R 15 represents hydrogen, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 25 carbon atoms; L represents a monoanionic ligand; and n represents 1 or 2.

[0146] The organometallic complex represented by the general formula (G-15) is a hetero-compound, which is a metal complex having two or more kinds of ligands among the organometallic complexes represented by the general formula (G-5). The hetero-compound organometallic complex is preferable because the emission color and sublimation property can be adjusted by selecting the combination of ligands.

[0147] In the general formulae (G-11) to (G-15), the monoanionic ligand represented by L is preferably a monoanionic bidentate chelate ligand having a β-diketone structure, a monoanionic bidentate chelate ligand having a carboxyl group, a monoanionic bidentate chelate ligand having a phenolic hydroxyl group, a monoanionic bidentate chelate ligand in which both of the two coordinating elements are nitrogen, or a bidentate ligand that forms a metal-carbon bond with iridium by cyclometallation. Specifically, it is preferably any of the following general formulae (L1) to (L9).

[0148] [ka]

[0149] In general formulas (L1) to (L9), R 21 ~R 86each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a halogeno group, a vinyl group, a cyano group, a substituted or unsubstituted haloalkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 6 carbon atoms, a substituted or unsubstituted alkylthio group having 1 to 6 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 13 carbon atoms. 1 or A 13 are independently sp bonds to nitrogen or hydrogen 2 Hybridized carbon or substituted sp 2 It represents a hybrid carbon, and the substituent is any one of an alkyl group having 1 to 6 carbon atoms, a halogeno group, a haloalkyl group having 1 to 6 carbon atoms, or a phenyl group.

[0150] Here, the hetero-organic organometallic complex has a plurality of types of ligands, and it is preferable that the HOMO and LUMO of the organometallic complex are distributed among the same type of ligands. In this structure, the organometallic complex can have particularly good emission efficiency. Thus, in the general formulas (G-11) to (G-15), it is particularly preferable that L is (L8) or (L9). The organometallic complex of one embodiment of the present invention has a five-membered imidazole skeleton. Therefore, it is preferable that L also has a structure having a five-membered skeleton. With this structure, the HOMO and LUMO of the organometallic complex are easily distributed among the same ligands.

[0151] <Examples of Substituents> In general formulae (G-1) to (G-15), R 1 ~R 15represents, for example, hydrogen, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 25 carbon atoms, or an electron-withdrawing group. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, and an n-hexyl group. Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. Examples of the aryl group include a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, and a spirofluorenyl group. Examples of the electron-withdrawing group include a halogeno group, a cyano group, a nitro group, a carbonyl group, and a haloalkyl group. Specific examples of the haloalkyl group include a fluoromethyl group. More specific examples include groups represented by the following structural formulas (R-1) to (R-43). In particular, halogeno, cyano, and trifluoromethyl groups are preferred because they have high electron-withdrawing properties and are highly stable. 1 ~R 4 and R 5 ~R 13 The group represented by the formula is not limited to these.

[0152] [ka]

[0153] At this time, R 1 ~R 10 When the substituent is hydrogen, the organometallic complex of one embodiment of the present invention can be easily and inexpensively synthesized. The organometallic complex of one embodiment of the present invention is electrochemically stable and has good reliability, which is preferable. In addition, when the substituent is a group other than hydrogen, the heat resistance of the organometallic complex of one embodiment of the present invention can be improved. When the substituent is an alkyl group or a cycloalkyl group as in (R-2) to (R-15), the solubility in an organic solvent is good, and therefore the purification of the organometallic complex of one embodiment of the present invention can be easily performed. When the aryl group does not have an alkyl group or a cycloalkyl group as in (R-16), (R-22) to (R-28), (R-31), and (R-32), the aryl group is electrochemically stable and has good reliability.

[0154] In addition, in the general formulae (G-1), (G-6) and (G-11), examples of the substituted or unsubstituted aryl group having 6 to 25 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group and a spirofluorenyl group. Specifically, groups represented by the following structural formulae (Ar-1) to (Ar-25) can be applied. The group represented by Ar is not limited to these. In addition, it may further have a substituent.

[0155] [ka]

[0156] In addition, in the general formulas (L1) to (L9), R 21 ~R 86 each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a halogeno group, a vinyl group, a cyano group, a substituted or unsubstituted haloalkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 6 carbon atoms, a substituted or unsubstituted alkylthio group having 1 to 6 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 13 carbon atoms. Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, and n-hexyl groups. Examples of the halogeno group include fluoro, chloro, bromo, and iodo groups. Examples of the vinyl group include vinyl and vinyl acetate groups. Examples of the haloalkyl group include trifluoromethyl, pentafluoroethyl, and trichloromethyl groups. Examples of the alkoxy group include methoxy, ethoxy, and phenoxy groups. Examples of the alkylthio group include propylthio and butylthio groups. Examples of the aryl group include phenyl, naphthyl, biphenyl, and fluorenyl groups. More specifically, examples of the groups include those represented by the following structural formulas (R-50) to (R-95). In addition, R 21 ~R 86 The group represented by the formula is not limited to these.

[0157] [ka]

[0158] In the above general formulae (G1) to (G15), Ar, R 1 ~R 15 and R 21 ~R 86 When further having a substituent, the substituent can be an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 25 carbon atoms. Examples of the alkyl group can be a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, an n-hexyl group, etc., examples of the cycloalkyl group can be a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc., and specific examples of the aryl group can be a phenyl group, a naphthyl group, a fluorenyl group, etc.

[0159] <Specific examples of compounds> Specific structures of the compounds represented by the general formulae (G-1) to (G-15) include organometallic complexes represented by the following structural formulae (100) to (123) and structural formulae (200) to (223). Note that the organometallic complexes represented by the general formulae (G-1) to (G-15) are not limited to the following examples.

[0160] [ka]

[0161] [ka]

[0162] [ka]

[0163] [ka]

[0164] [ka]

[0165] [ka]

[0166] [ka]

[0167] Note that the organometallic complex in this embodiment can be formed into a film by a deposition method (including a vacuum deposition method), an ink-jet method, a coating method, a gravure printing method, or the like.

[0168] Note that this embodiment mode can be appropriately combined with other embodiment modes.

[0169] (Embodiment 2)

[0170] In this embodiment, an example of a synthesis method for an organometallic complex of one embodiment of the present invention will be described.

[0171] <Method for synthesizing 1H-naphtho[1,2-d]imidazole derivative represented by general formula (g-1)> An example of a method for synthesizing a 1H-naphtho[1,2-d]imidazole derivative represented by the following general formula (g-1) will be described. An organometallic complex of one embodiment of the present invention having a structure represented by general formula (G-1) has a 1H-naphtho[1,2-d]imidazole derivative represented by general formula (g-1) as a ligand. Therefore, by synthesizing an Ir complex using the 1H-naphtho[1,2-d]imidazole derivative represented by general formula (g-1), an organometallic complex of one embodiment of the present invention can be synthesized as described below.

[0172] [ka]

[0173] In general formula (g-1), R 1 ~R 10 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 25 carbon atoms, or an electron-withdrawing group, and Ar represents a substituted or unsubstituted aryl group having 6 to 25 carbon atoms.

[0174] As shown in the following scheme (S-1), a 1H-naphtho[1,2-d]imidazole derivative represented by general formula (g-1) can be obtained by reacting an arylaldehyde compound or an arylcarboxylic acid chloride (M1) with an o-naphthalenediamine derivative (M2) substituted at the N-position with Ar.

[0175] [ka]

[0176] In Scheme (S-1), R 1 ~R 10 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 25 carbon atoms, or an electron-withdrawing group, and Ar represents a substituted or unsubstituted aryl group having 6 to 25 carbon atoms.

[0177] <Method for synthesizing organometallic complexes represented by general formula (G-6)> Next, among the methods for synthesizing an organometallic complex having a structure represented by general formula (G-1), an example of a method for synthesizing an organometallic complex represented by general formula (G-6) will be described.

[0178] As shown in the following scheme (S-2), a 1H-naphtho[1,2-d]imidazole derivative represented by general formula (g-1) is mixed with an iridium metal compound containing a halogen (iridium chloride hydrate, ammonium hexachloroiridate, etc.) or an iridium organometallic complex compound (acetylacetonato complex, diethylsulfide complex, etc.) and then heated to obtain an organometallic complex having a structure represented by general formula (G-6). This heating process may also be carried out after dissolving the 1H-naphtho[1,2-d]imidazole derivative represented by general formula (g-1) and an iridium metal compound containing a halogen or an iridium organometallic complex in an alcohol solvent (glycerol, ethylene glycol, 2-methoxyethanol, 2-ethoxyethanol, etc.). In scheme (S-2), R 1 ~R 10 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 25 carbon atoms, or an electron-withdrawing group, and Ar represents a substituted or unsubstituted aryl group having 6 to 25 carbon atoms.

[0179] [ka]

[0180] However, the method for synthesizing the organometallic complex of the present invention is not limited to only scheme (S-2).

[0181] <Method for synthesizing organometallic complexes represented by general formula (G-11)> Next, among the methods for synthesizing an organometallic complex containing a structure represented by general formula (G-1), an example of a method for synthesizing an organometallic complex represented by general formula (G-11) will be described.

[0182] As shown in the following scheme (S-3), a 1H-naphtho[1,2-d]imidazole derivative represented by the general formula (g-1) or L and an iridium compound containing a halogen (iridium chloride, iridium bromide, iridium iodide, etc.) are heated in an inert gas atmosphere without a solvent, or in an alcohol-based solvent (glycerol, ethylene glycol, 2-methoxyethanol, 2-ethoxyethanol, etc.) alone, or in a mixed solvent of one or more alcohol-based solvents and water, to obtain a binuclear complex (P1) of a 1H-naphtho[1,2-d]imidazole derivative, which is a type of organometallic complex having a structure bridged by halogen, or a binuclear complex (P2) containing a monoanionic bidentate ligand. In scheme (S-3), X represents a halogen atom, and R 1 ~R 10 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 25 carbon atoms, or an electron-withdrawing group, and Ar represents a substituted or unsubstituted aryl group having 6 to 25 carbon atoms.

[0183] [ka]

[0184] Furthermore, as shown in the following scheme (S-4), the binuclear complex (P1) or (P2) obtained in the above synthesis scheme (S-3) is reacted with a 1H-naphtho[1,2-d]imidazole derivative or L represented by general formula (g-1) in an inert gas atmosphere to obtain an organometallic complex represented by general formula (G-11) which is one embodiment of the present invention. Here, the obtained organometallic complex may be further reacted by irradiating it with light or heat to obtain isomers such as geometric isomers and optical isomers, which are also organometallic complexes represented by general formula (G-11) which are one embodiment of the present invention. In scheme (S-4), X represents a halogen atom, R 1 ~R 10each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 25 carbon atoms, or an electron-withdrawing group, and Ar represents a substituted or unsubstituted aryl group having 6 to 25 carbon atoms.

[0185] [ka]

[0186] However, the method for synthesizing the organometallic complex of the present invention is not limited to only the schemes (S-3) and (S-4).

[0187] (Embodiment 3) In this embodiment, a light-emitting element including an organometallic complex which is one embodiment of the present invention will be described below with reference to FIG.

[0188] <Configuration example 1 of light-emitting element> First, a structure of a light-emitting element of one embodiment of the present invention will be described below with reference to FIGS.

[0189] FIG. 1A is a schematic cross-sectional view of a light-emitting element 150 of one embodiment of the present invention.

[0190] The light-emitting element 150 has a pair of electrodes (electrode 101 and electrode 102) and an EL layer 100 provided between the pair of electrodes. The EL layer 100 has at least a light-emitting layer 140.

[0191] In addition to the light-emitting layer 140, the EL layer 100 shown in FIG. 1A includes functional layers such as a hole-injection layer 111, a hole-transport layer 112, an electron-transport layer 118, and an electron-injection layer 119.

[0192] In this embodiment, among the pair of electrodes, electrode 101 is described as the anode and electrode 102 as the cathode. However, the structure of the light-emitting element 150 is not limited to this. That is, electrode 101 may be the cathode, electrode 102 may be the anode, and the lamination of each layer between the electrodes may be in the reverse order. That is, from the anode side, the hole injection layer 111, the hole transport layer 112, the light-emitting layer 140, the electron transport layer 118, and the electron injection layer 119 may be laminated in this order.

[0193] Note that the structure of the EL layer 100 is not limited to the structure shown in Fig. 1(A), and may be a structure having at least one selected from the hole injection layer 111, the hole transport layer 112, the electron transport layer 118, and the electron injection layer 119. Alternatively, the EL layer 100 may be a structure having a functional layer having functions such as reducing the injection barrier of holes or electrons, improving the transportability of holes or electrons, inhibiting the transportability of holes or electrons, or suppressing the quenching phenomenon by the electrodes. Note that each functional layer may be a single layer or a structure in which a plurality of layers are laminated.

[0194] The light-emitting element 150 only needs to contain an organometallic complex according to one aspect of the present invention in any layer of the EL layer 100. Note that the organometallic complex has a good quantum yield. Therefore, by using it as the guest material of the light-emitting layer 140, a light-emitting element with good luminous efficiency can be obtained.

[0195] Fig. 1(B) is a cross-sectional schematic view showing an example of the light-emitting layer 140 shown in Fig. 1(A). The light-emitting layer 140 shown in Fig. 1(B) has a host material 141 and a guest material 142. The host material 141 may be composed of a single organic compound, or may be a co-host system having an organic compound 141_1 and an organic compound 141_2. The organometallic complex according to one aspect of the present invention can be preferably used as the guest material 142.

[0196] In addition, a light-emitting organic material may be used as the guest material 142. Examples of the light-emitting organic material include a material that can emit fluorescence (hereinafter referred to as a fluorescent material) and a material that can emit phosphorescence (hereinafter referred to as a phosphorescent material). A phosphorescent material is preferable because of its high emission efficiency. For this reason, the organometallic complex of one embodiment of the present invention can be suitably used. In the following description, a structure in which a phosphorescent material is used as the guest material 142 will be described. Note that the guest material 142 may be interpreted as a phosphorescent material.

[0197] 1B, when two host materials such as organic compounds 141_1 and 141_2 are used in the light-emitting layer (co-host system), one electron-transporting material and one hole-transporting material are generally used for the two host materials. This configuration is preferable because it reduces the hole injection barrier between the hole-transporting layer 112 and the light-emitting layer 140 and the electron injection barrier between the electron-transporting layer 118 and the light-emitting layer 140, thereby reducing the driving voltage.

[0198] <Light Emitting Mechanism of Light Emitting Device> Next, the light emitting mechanism of the light emitting layer 140 will be described below.

[0199] The organic compound 141_1 and the organic compound 141_2 contained in the host material 141 in the light-emitting layer 140 may form an exciplex (also referred to as an exciplex). Hereinafter, a case where the organic compound 141_1 and the organic compound 141_2 form an exciplex will be described.

[0200] 1C shows the correlation between the energy levels of the organic compound 141_1, the organic compound 141_2, and the guest material 142 in the light-emitting layer 140. The notations and symbols in FIG. 1C are as follows. In the following description, the organic compound 141_1 is an electron-transporting material, and the organic compound 141_2 is a hole-transporting material. ·Host(141_1): Organic compound 141_1 (host material) ·Host(141_2): Organic compound 141_2 (host material) Guest (142): Guest material 142 (phosphorescent compound) ·S PH1 : S1 level of organic compound 141_1 (host material) T PH1 :T1 level of organic compound 141_1 (host material) ·S PH2 : S1 level of organic compound 141_2 (host material) T PH2 :T1 level of organic compound 141_2 (host material) ·S PG : S1 level of guest material 142 (phosphorescent compound) T PG :T1 level of guest material 142 (phosphorescent compound) ·S PE : S1 level of the exciplex T PE :T1 level of the exciplex

[0201] The organic compound 141_1 and the organic compound 141_2 form an exciplex, and the S1 level (S PE ) and T1 level (T PE ) are adjacent energy levels (see route E1 in Figure 1(C)).

[0202] The organic compound 141_1 receives an electron and the organic compound 141_2 receives a hole, and thus an exciplex is rapidly formed. Alternatively, when one of the compounds is excited, it quickly interacts with the other compound to form an exciplex. Therefore, most of the excitons in the light-emitting layer 140 exist as exciplexes. The excitation energy level (S PE or T PE ) is the S1 level (S PH1 and S PH2), the excited state of the host material 141 can be formed with lower excitation energy. This allows the driving voltage of the light-emitting element to be reduced. Note that the organic compound 141_1 may receive holes and the organic compound 141_2 may receive electrons to form an exciplex.

[0203] And the (S PE ) and (T PE ) to the T1 level of the guest material 142 (phosphorescent compound), thereby emitting light (see routes E2 and E3 in FIG. 1C).

[0204] In addition, the T1 level of the exciplex (T PE ) is the T1 level (T PG ) is preferably larger than the singlet excitation energy and triplet excitation energy of the generated exciplex. PE ) and T1 level (T PE ) to the T1 level (T PG ) energy can be transferred to

[0205] In order to efficiently transfer excitation energy from the exciplex to the guest material 142, the T1 level (T PE ) is the T1 level (T PH1 and T PH2 ) is preferably equal to or smaller than the organic compound 141_1 and the organic compound 141_2. This makes it difficult for the organic compounds (the organic compound 141_1 and the organic compound 141_2) to quench the triplet excitation energy of the exciplex, and energy transfer from the exciplex to the guest material 142 occurs efficiently.

[0206] In addition, when the combination of the organic compound 141_1 and the organic compound 141_2 is a combination of a compound having a hole transporting property and a compound having an electron transporting property, the carrier balance can be easily controlled by the mixing ratio. Specifically, the compound having a hole transporting property: the compound having an electron transporting property is preferably in the range of 1:9 to 9:1 (weight ratio). In addition, since the carrier balance can be easily controlled by having this configuration, the carrier recombination region can also be easily controlled.

[0207] In addition, the above-described processes of routes E2 and E3 are sometimes referred to as ExTET (Exciplex-Triplet Energy Transfer) in this specification. In other words, in the light-emitting layer 140, excitation energy is provided from the exciplex to the guest material 142. In this case, it is not necessarily the case that T PE From S PE The efficiency of reverse intersystem crossing to S is not required to be high. PE Since the quantum yield of light emission from the light-emitting diode is not necessarily high, a wide range of materials can be selected. In addition, by using ExTET, a light-emitting element with good light-emitting efficiency, reduced driving voltage, and good reliability can be obtained.

[0208] The combination of the organic compound 141_1 and the organic compound 141_2 may be any combination capable of forming an exciplex, but it is preferable that one of them has a lower HOMO level than the other and a lower LUMO level than the other.

[0209] <Material> Next, components of the light-emitting element according to one embodiment of the present invention will be described in detail below.

[0210] <Light-emitting layer> In the light-emitting layer 140, the host material 141 is present in the largest amount by weight, and the guest material 142 is dispersed in the host material 141. When the guest material 142 is a phosphorescent compound, the T1 level of the host material 141 (the organic compound 141_1 and the organic compound 141_2) of the light-emitting layer 140 is preferably higher than the T1 level of the guest material of the light-emitting layer 140 (the guest material 142).

[0211] The organic compound 141_1 is preferably a compound having a nitrogen-containing six-membered heteroaromatic ring skeleton. Specific examples include compounds having a pyridine skeleton, a diazine skeleton (pyrazine skeleton, pyrimidine skeleton, and pyridazine skeleton), and a triazine skeleton. Examples of compounds having a basic nitrogen-containing heteroaromatic ring skeleton include pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, triazine derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, phenanthroline derivatives, and purine derivatives. In addition, a material having a higher electron transporting property than holes (electron transporting material) can be used as the organic compound 141_1, and a material having a hole transporting property of 1×10 -6 cm 2 It is preferable that the material has an electron mobility of .beta. / Vs or more.

[0212] Specifically, for example, heteroaromatic ring compounds having a pyridine skeleton, such as bathophenanthroline (abbreviation: Bphen) and bathocuproine (abbreviation: BCP), 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), and 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II) are available. mCzBPDBq), 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), (2-[3-(3,9'-bi-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline)( Aromatic 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-2-(4,6-diphenyl-2-phenyl)pyrimidine (abbreviation: 2mCzCzPDBq), 4,6-bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), and 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), Heteroaromatic ring compounds having a triazine skeleton, such as 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy) and 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), can also be used.Among the above-mentioned heteroaromatic ring compounds, heteroaromatic ring compounds having a triazine skeleton, a diazine (pyrimidine, pyrazine, pyridazine) skeleton, or a pyridine skeleton are preferred because they are stable and reliable. In addition, heteroaromatic ring compounds having such skeletons have high electron transport properties and contribute to reducing the driving voltage. Polymer compounds such as poly(2,5-pyridinediyl) (abbreviation: PPy), poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)] (abbreviation: PF-Py), and poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2'-bipyridine-6,6'-diyl)] (abbreviation: PF-BPy) can also be used. The substances mentioned here are mainly 1×10 -6 cm 2 A substance having an electron mobility of 1 / Vs or more. Note that any substance other than the above may be used as long as it has a higher electron transporting property than a hole transporting property.

[0213] As the organic compound 141_2, a compound having a nitrogen-containing five-membered heteroaromatic ring skeleton or a tertiary amine skeleton is preferable. Specific examples include compounds having a pyrrole skeleton or an aromatic amine skeleton. Examples include indole derivatives, carbazole derivatives, and triarylamine derivatives. Examples of the nitrogen-containing five-membered heteroaromatic ring skeleton include an imidazole skeleton, a triazole skeleton, and a tetrazole skeleton. As the organic compound 141_2, a material having a higher hole transporting property than that of an electron (hole transporting material) can be used, and the organic compound 141_2 can be used in a concentration of 1×10 -6 cm 2 It is preferable that the hole transporting material is a material having a hole mobility of 1 / Vs or more. The hole transporting material may be a polymer compound.

[0214] Specific examples of these materials with high hole transport properties include aromatic amine compounds such as N,N'-di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), N,N'-bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviation: DNTPD), and 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B).

[0215] Specific examples of the carbazole derivative include 3-[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA1), 3,6-bis[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA2), and 3,6-bis[N-(4-diphenylaminophenyl)-N-(1-naphthyl)amino]-9-phenylcarbazole (abbreviation: PCzTP N2), 3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2), 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1), and the like can be mentioned.

[0216] Other examples of carbazole derivatives that can be used include 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB), 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA), and 1,4-bis[4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene.

[0217] In addition, N,N-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: CzA1PA), 4-(10-phenyl-9-anthryl)triphenylamine (abbreviation: DPhPA), 4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), N,9-diphenyl-N-{4-[4-(10-phenyl-9-anthryl)phenyl]phenyl}-9H-carbazol-3-amine (abbreviation: PCAPA), carbazole-3-amine (abbreviation: PCAPBA), N,9-diphenyl-N-(9,10-diphenyl-2-anthryl)-9H-carbazole-3-amine (abbreviation: 2PCAPA), 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), 3,6-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: DPCzPA), N,N,N',N',N'',N'',N''',N'''-octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), etc. can be used.

[0218] In addition, polymer compounds such as poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphenylamine) (abbreviation: PVTPA), poly[N-(4-{N'-[4-(4-diphenylamino)phenyl]phenyl-N'-phenylamino}phenyl)methacrylamide] (abbreviation: PTPDMA), and poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine] (abbreviation: Poly-TPD) can also be used.

[0219] Furthermore, examples of materials with high hole transport properties include 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB or α-NPD), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4',4''-tris(carbazol-9-yl)triphenylamine (abbreviation: TCTA), 4,4',4''-tris[N-(1-naphthyl)-N-phenylamino]triphenylamine (abbreviation: :1'-TNATA), 4,4',4''-tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA), 4,4',4''-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (abbreviation: MTDATA), 4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl 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 (DFLADFL), N-(9,9-dimethyl-2-diphenylamino-9H-fluoren-7-yl)diphenylamine (DPNF), 2-[N-(4- diphenylaminophenyl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: DPASF), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-Di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 4-phenyldiphenyl-(9-phenyl-9H-carbazol-3-yl)amine (abbreviation: PCA1BP), N,N'-bis(9-phenylcarbazol-3-yl)-N,N'-diphenylbenzene-1,3-diamine (abbreviation: PCA2B), N,N',N''-triphenyl-N,N',N''-tris(9-phenyl Carbazol-3-yl)benzene-1,3,5-triamine (abbreviation: PCA3B), N-(4-biphenyl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9-phenyl-9H-carbazol-3-amine (abbreviation: PCBiF), N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), 9,9-dimethyl N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]spiro-9,9'-bifluoren-2-amine (abbreviation: PCBASF), 2-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: PCASF), 2,7-bis[N- Aromatic amine compounds such as (4-diphenylaminophenyl)-N-phenylamino]-spiro-9,9'-bifluorene (abbreviation: DPA2SF), N-[4-(9H-carbazol-9-yl)phenyl]-N-(4-phenyl)phenylaniline (abbreviation: YGA1BP), and N,N'-bis[4-(carbazol-9-yl)phenyl]-N,N'-diphenyl-9,9-dimethylfluorene-2,7-diamine (abbreviation: YGA2F) can be used. In addition, 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 3-[4-(9-phenanthryl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPPn), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 3,6-di(9H-carbazol-9-yl)-9-phenyl-9H-carbazole (abbreviation: PhCzGI), 2,8-di(9H-carbazol-9-yl)-dibenzothiophene (abbreviation: Cz2DBT), and other amine compounds and carbazole compounds can be used. Among the above-mentioned compounds, compounds having a pyrrole skeleton or an aromatic amine skeleton are preferred because they are stable and reliable. In addition, compounds having such skeletons have high hole transport properties and contribute to reducing the driving voltage.

[0220] As the organic compound 141_2, a compound having a nitrogen-containing five-membered heteroaromatic ring skeleton such as an imidazole skeleton, a triazole skeleton, or a tetrazole skeleton can be used. Specifically, for example, 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 9-[4-(4,5-diphenyl-4H-1,2,4-triazol-3-yl)phenyl]-9H-carbazole (abbreviation: CzTAZ1), 2,2′,2″-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophene-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), etc. can be used.

[0221] In addition, in the light-emitting layer 140, an organometallic complex of one embodiment of the present invention can be preferably used as the guest material 142. Since the organometallic complex of one embodiment of the present invention has a high quantum yield, a light-emitting element with high emission efficiency can be obtained. In addition, in the case of a light-emitting element having a plurality of light-emitting units such as the light-emitting element 250 described later, the organic compound of one embodiment of the present invention is preferably used for the light-emitting layer of one of the light-emitting units. Although there is no particular limitation on the guest material used for the other light-emitting units, preferred fluorescent compounds include anthracene derivatives, tetracene derivatives, chrysene derivatives, phenanthrene derivatives, pyrene derivatives, perylene derivatives, stilbene derivatives, acridone derivatives, coumarin derivatives, phenoxazine derivatives, and phenothiazine derivatives, and for example, the following substances can be used:

[0222] Specifically, 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine (abbreviation: PAP2BPy), 5,6-bis[4'-(10-phenyl-9-anthryl)biphenyl-4-yl]-2,2'-bipyridine (abbreviation: PAPP2BPy), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), )phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn), N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-N,N'-bis(4-tert-butylphenyl)pyrene-1,6-diamine (abbreviation: 1,6tBu-FLPAPrn), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-3,8-dicyclohexylpyrene-1,6-diamine (abbreviation: ch-1,6FLPAPrn), N,N'-bis[4-(9H-carbazol-9-yl)phenyl]- phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetra(tert -butyl)perylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), N,N''-(2-tert-butylanthracene-9,10-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,N,N,N',N',N'',N'',N''',N'''-Octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), Coumarin 30, N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,9 -Diphenyl-9H-carbazol-3-amine (abbreviation: 2PCABPhA), N-(9,10-diphenyl-2-anthryl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPABPhA), 9,10-bis(1,1'-biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracene-2-amine N,N,9-triphenylanthracene-9-amine (abbreviation: DPhAPhA), Coumarin 6, Coumarin 545T, N,N'-diphenylquinacridone (abbreviation: DPQd), Rubrene, 2,8-di-tert-butyl-5,11-bis(4-tert-butylphenyl)-6,12-diphenyltetracene (abbreviation: TBRb), Nile Red, 5,12-bis(1,1'-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyran-4-ylidene)propanedinitrile (abbreviation: DCM1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM2), N,N,N',N'-tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviation: p-mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB), 2-(2 ,6-bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDCM), 2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJTM), 5,10,15,20-tetraphenylbisbenzo[5,6]indeno[1,2,3-cd:1',2',3'-lm]perylene, and the like.

[0223] Phosphorescent compounds that can be used as guest materials include iridium, rhodium, or platinum-based organometallic complexes or metal complexes, and among these, organic iridium complexes, such as iridium-based orthometal complexes, are preferred. Examples of orthometalating ligands include 4H-triazole ligands, 1H-triazole ligands, imidazole ligands, pyridine ligands, pyrimidine ligands, pyrazine ligands, and isoquinoline ligands. Examples of metal complexes include platinum complexes with porphyrin ligands.

[0224] Examples of substances having a blue or green emission peak include tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN2]phenyl-κC}iridium(III) (abbreviation: [Ir(mpptz-dmp)3]), tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Mptz)3]), Organometallic iridium complexes with a 4H-triazole skeleton, such as tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(iPrptz-3b)3]) and tris[3-(5-biphenyl)-5-isopropyl-4-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(iPr5btz)3]), and tris[3 Organometallic iridium complexes with 1H-triazole skeletons, such as 1-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(Mptz1-mp)3]) and tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Prptz1-Me)3]), and fac-tris[1-(2,6-diisopropyl) Organometallic iridium complexes with an imidazole skeleton, such as tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: [Ir(iPrpmi)3]) and tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: [Ir(dmpimpt-Me)3]), and bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]iridium(III) tetrakis(1-pyrazolyl)borate (abbreviation: FIr6), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]iridium(III) picolinate (abbreviation: FIrpic), bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinato-N,C 2’}Iridium(III) picolinate (abbreviation: [Ir(CF3ppy)2(pic)]), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]iridium (III) acetylacetonate (abbreviation: [FIr (acac)]) and other organometallic iridium complexes having a phenylpyridine derivative having an electron-withdrawing group as a ligand. Among the above, organometallic iridium complexes having a nitrogen-containing five-membered heteroaromatic ring skeleton such as a 4H-triazole skeleton, a 1H-triazole skeleton, and an imidazole skeleton are particularly preferred because they have high triplet excitation energy and are also excellent in reliability and luminous efficiency.

[0225] Examples of substances having a green or yellow emission peak include tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)3]), tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)3]), (acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)2(acac)] ... (acetylacetonato)bis[4-(2-norbornyl)-6-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(nbppm)2(acac)]), (acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(tBuppm)2(acac)]) Organogold compounds with pyrimidine skeletons such as (acetylacetonato)bis{4,6-dimethyl-2-[6-(2,6-dimethylphenyl)-4-pyrimidinyl-κN3]phenyl-κC}iridium(III) (abbreviation: [Ir(dmppm-dmp)2(acac)]), (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm)2(acac)]) iridium complexes with pyrazine skeletons such as (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinate)iridium(III) (abbreviation: [Ir(mppr-Me)2(acac)]) and (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinate)iridium(III) (abbreviation: [Ir(mppr-iPr)2(acac)]), and tris(2-phenylpyrazinate-N,C 2’ ) Iridium(III) (abbreviation: [Ir(ppy)3]), bis(2-phenylpyridinato-N,C 2’)iridium(III) acetylacetonate (abbreviation: [Ir(ppy)2(acac)]), bis(benzo[h]quinolinato)iridium(III) acetylacetonate (abbreviation: [Ir(bzq)2(acac)]), tris(benzo[h]quinolinato)iridium(III) (abbreviation: [Ir(bzq)3]), tris(2-phenylquinolinato-N,C 2’ ) Iridium(III) (abbreviation: [Ir(pq)3]), bis(2-phenylquinolinato-N,C 2’ Organometallic iridium complexes with pyridine skeletons such as iridium(III) acetylacetonate (abbreviation: [Ir(pq)2(acac)]) and bis(2,4-diphenyl-1,3-oxazolato-N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: [Ir(dpo)2(acac)]), bis{2-[4'-(perfluorophenyl)phenyl]pyridinato-N,C 2’}Iridium(III) acetylacetonate (abbreviation: [Ir(p-PF-ph)2(acac)]), bis(2-phenylbenzothiazolato-N,C 2’ Examples of such complexes include organometallic iridium complexes such as iridium(III) acetylacetonate (abbreviation: [Ir(bt)2(acac)]) and rare earth metal complexes such as tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviation: [Tb(acac)3(Phen)]). Among the above, organometallic iridium complexes having a pyrimidine skeleton are particularly preferred because of their outstanding reliability and luminous efficiency.

[0226] Examples of substances having a yellow or red emission peak include those having a pyrimidine skeleton, such as (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III) (abbreviation: [Ir(5mdppm)2(dibm)]), bis[4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(5mdppm)2(dpm)]), and bis[4,6-di(naphthalen-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(d1npm)2(dpm)]). and organometallic iridium complexes with pyrazine skeletons such as (acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: [Ir(tppr)2(acac)]), bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: Ir(tppr)2(dpm)), and (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: [Ir(Fdpq)2(acac)]). 2’ ) Iridium(III) (abbreviation: [Ir(piq)3]), bis(1-phenylisoquinolinato-N,C 2’In addition to organometallic iridium complexes having a pyridine skeleton such as iridium(III) acetylacetonate (abbreviation: [Ir(piq)2(acac)]), platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum(II) (abbreviation: [PtOEP]), and rare earth metal complexes such as tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III) (abbreviation: [Eu(DBM)3(Phen)]) and tris[1-(2-thenoyl)-3,3,3-trifluoroacetonate](monophenanthroline)europium(III) (abbreviation: [Eu(TTA)3(Phen)]) can be mentioned. Among the above, organometallic iridium complexes having a pyrimidine skeleton are particularly preferred because they are remarkably excellent in reliability and luminous efficiency. Furthermore, an organometallic iridium complex having a pyrazine skeleton can emit red light with good chromaticity.

[0227] Since an organic compound having a benzofuropyridine skeleton or a benzothienopyridine skeleton has a high T1 level, it can be suitably used as a host material of an emission layer in which a substance capable of converting triplet excitation energy into light emission is used as an emission material. Therefore, the emission material contained in the emission layer 140 is preferably a material capable of converting triplet excitation energy into light emission. In addition to the above-mentioned phosphorescent compounds, examples of materials capable of converting triplet excitation energy into light emission include thermally activated delayed fluorescence (TADF) materials. Therefore, the part described as a phosphorescent compound may be read as a thermally activated delayed fluorescence material. Note that a thermally activated delayed fluorescence material is a material that has a small difference between the triplet excitation energy level and the singlet excitation energy level and has a function of converting energy from a triplet excited state to a singlet excited state by reverse intersystem crossing. Therefore, it is possible to upconvert the triplet excited state to a singlet excited state by a small amount of thermal energy (reverse intersystem crossing), and it is possible to efficiently exhibit light emission (fluorescence) from the singlet excited state. In addition, the condition for efficiently obtaining thermally activated delayed fluorescence is that the energy difference between the triplet excitation energy level and the singlet excitation energy level is preferably greater than 0 eV and less than 0.2 eV, and more preferably greater than 0 eV and less than 0.1 eV.

[0228] When the thermally activated delayed fluorescent material is composed of one type of material, for example, the following material can be used.

[0229] First, there are fullerene and its derivatives, acridine derivatives such as proflavine, eosin, etc. Also, there are metal-containing porphyrins including magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), palladium (Pd), etc. Examples of the metal-containing porphyrin include protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF2(OEP)), etioporphyrin-tin fluoride complex (SnF2(Etio I)), and octaethylporphyrin-platinum chloride complex (PtCl2OEP).

[0230] In addition, as the thermally activated delayed fluorescent material composed of one kind of material, a heteroaromatic ring compound having a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring can be used. Specifically, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 2-[4-(10H-phenoxazin-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: PXZ-TRZ), 3-[4- (5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), 10-phenyl-10H,10'H-spiro[acridin-9,9'-anthracene]-10'-one (abbreviation: ACRSA), etc. The heteroaromatic ring compound has a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring, and therefore has high electron transport properties and hole transport properties, making it preferable. Among the skeletons having a π-electron-deficient heteroaromatic ring, a diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton) or a triazine skeleton is preferred because it is stable and reliable. In addition, among the skeletons having a π-electron-rich heteroaromatic ring, an acridine skeleton, a phenoxazine skeleton, a thiophene skeleton, a furan skeleton, and a pyrrole skeleton are stable and reliable, so it is preferred to have one or more selected from these skeletons. Note that, as the pyrrole skeleton, an indole skeleton, a carbazole skeleton, and a 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole skeleton are particularly preferred.In addition, a substance in which a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded to each other is particularly preferable because the π-electron-rich heteroaromatic ring has strong donor properties and the π-electron-deficient heteroaromatic ring has strong acceptor properties, and the difference between the energy levels of the singlet excited state and the triplet excited state is small.

[0231] The light-emitting layer 140 may contain a material other than the host material 141 and the guest material 142 .

[0232] Materials that can be used for the light-emitting layer 140 are not particularly limited, and examples thereof include condensed polycyclic aromatic compounds such as anthracene derivatives, phenanthrene derivatives, pyrene derivatives, chrysene derivatives, and dibenzo[g,p]chrysene derivatives. Specific examples thereof include 9,10-diphenylanthracene (abbreviation: DPAnth), 6,12-dimethoxy-5,11-diphenylchrysene, 9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA), 9,10- Examples of the suitable materials include di(2-naphthyl)anthracene (abbreviation: DNA), 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 9,9'-bianthryl (abbreviation: BANT), 9,9'-(stilbene-3,3'-diyl)diphenanthrene (abbreviation: DPNS), 9,9'-(stilbene-4,4'-diyl)diphenanthrene (abbreviation: DPNS2), and 1,3,5-tri(1-pyrenyl)benzene (abbreviation: TPB3). Among these and known materials, one or more materials having a singlet excitation energy level or triplet excitation energy level higher than the excitation energy level of the guest material 142 may be selected and used.

[0233] Furthermore, for example, a compound having a heteroaromatic ring skeleton such as an oxadiazole derivative can be used in the light-emitting layer 140. Specifically, for example, heteroaromatic ring compounds such as 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), and 4,4′-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOs) can be mentioned.

[0234] In addition, metal complexes having a heteroaromatic ring (e.g., zinc and aluminum-based metal complexes) can be used in the light-emitting layer 140. For example, metal complexes having a quinoline ligand, a benzoquinoline ligand, an oxazole ligand, or a thiazole ligand can be used. Specifically, for example, metal complexes having a quinoline skeleton or a benzoquinoline skeleton, such as tris(8-quinolinolato)aluminum(III) (abbreviation: Alq), tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviation: Almq3), bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq2), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (abbreviation: BAlq), and bis(8-quinolinolato)zinc(II) (abbreviation: Znq), can be used. In addition, metal complexes having oxazole or thiazole ligands, such as bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO) and bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ), can also be used.

[0235] The light-emitting layer 140 may be composed of two or more layers. For example, when the first light-emitting layer and the second light-emitting layer are laminated in order from the hole transport layer side to form the light-emitting layer 140, a substance having hole transport properties may be used as the host material of the first light-emitting layer, and a substance having electron transport properties may be used as the host material of the second light-emitting layer. The light-emitting materials of the first light-emitting layer and the second light-emitting layer may be the same or different materials, and may be materials having a function of emitting light of the same color or materials having a function of emitting light of different colors. By using light-emitting materials having a function of emitting light of different colors for the two light-emitting layers, respectively, multiple lights can be obtained simultaneously. In particular, it is preferable to select the light-emitting materials used for each light-emitting layer so that the light emitted by the two light-emitting layers becomes white.

[0236] The light-emitting layer 140 can be formed by a deposition method (including a vacuum deposition method), an inkjet method, a coating method, a gravure printing method, etc. In addition to the above-mentioned materials, the light-emitting layer 140 may contain an inorganic compound such as a quantum dot or a polymer compound (oligomer, dendrimer, polymer, etc.).

[0237] <Hole injection layer> The hole injection layer 111 has a function of promoting hole injection by reducing the hole injection barrier from one of the pair of electrodes (electrode 101 or electrode 102), and is formed of, for example, a transition metal oxide, a phthalocyanine derivative, or an aromatic amine. Examples of transition metal oxides include molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, and manganese oxide. Examples of phthalocyanine derivatives include phthalocyanine and metal phthalocyanine. Examples of aromatic amines include benzidine derivatives and phenylenediamine derivatives. Polymer compounds such as polythiophene and polyaniline can also be used, and a representative example is poly(ethylenedioxythiophene) / poly(styrenesulfonic acid), which is a self-doped polythiophene.

[0238] The hole injection layer 111 may be a layer having a composite material of a hole transporting material and a material exhibiting electron acceptance thereto. Alternatively, a stack of a layer containing a material exhibiting electron acceptance and a layer containing a hole transporting material may be used. Charges can be transferred between these materials in a stationary state or under the presence of an electric field. Examples of materials exhibiting electron acceptance include organic acceptors such as quinodimethane derivatives, chloranil derivatives, and hexaazatriphenylene derivatives. Specifically, the materials include compounds having an electron-withdrawing group (a halogen group or a cyano group), such as 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, and 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT-CN). In addition, transition metal oxides, for example oxides of metals from Group 4 to Group 8, may be used. Specific examples include vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, rhenium oxide, etc. Among these, molybdenum oxide is preferred because it is stable in the air, has low hygroscopicity, and is easy to handle.

[0239] As the hole transporting material, a material having a higher hole transporting property than that of electrons can be used. -6 cm 2 It is preferable that the material has a hole mobility of 1 / Vs or more. Specifically, aromatic amines, carbazole derivatives, aromatic hydrocarbons, stilbene derivatives, and the like, which are listed as hole transport materials that can be used for the light emitting layer 140, can be used. The hole transport material may be a polymer compound.

[0240] Other examples of hole transport materials include aromatic hydrocarbons, such as 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 2-tert-butyl-9,10-di(1-naphthyl)anthracene, 9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA), 2-tert-butyl-9,10-bis(4-phenylphenyl)anthracene (abbreviation: t-BuDBA), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA), 9,10-diphenylanthracene (abbreviation: DPAnth), 2-tert-butylanthracene (abbreviation: t-BuAnth), and 9,10-bis(4-methyl-1-naphthyl)anthracene (abbreviation: DMNA). , 2-tert-butyl-9,10-bis[2-(1-naphthyl)phenyl]anthracene, 9,10-bis[2-(1-naphthyl)phenyl]anthracene, 2,3,6,7-tetramethyl-9,10-di(1-naphthyl)anthracene, 2,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene, 9,9'-bianthryl, 10,10'-diphenyl-9,9'-bianthryl, 10,10'-bis(2-phenylphenyl)-9,9'-bianthryl, 10,10'-bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9'-bianthryl, anthracene, tetracene, rubrene, perylene, 2,5,8,11-tetra(tert-butyl)perylene, and the like. In addition, pentacene, coronene, etc. can also be used. -6 cm 2 It is more preferable to use an aromatic hydrocarbon having a hole mobility of 1 / Vs or more and a carbon number of 14 to 42.

[0241] The aromatic hydrocarbon may have a vinyl skeleton. Examples of aromatic hydrocarbons having a vinyl group include 4,4'-bis(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi) and 9,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene (abbreviation: DPVPA).

[0242] 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)tri(dibenzofuran) (abbreviation: DBF3P-II), 1,3,5-tri(dibenzothiophene-4-yl)-benzene (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)furan] Thiophene compounds such as 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-III), 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and 4-[3-(triphenylen-2-yl)phenyl]dibenzothiophene (abbreviation: mDBTPTp-II), furan compounds, fluorene compounds, triphenylene compounds, and phenanthrene compounds can be used. Among the above-mentioned compounds, compounds having a pyrrole skeleton, a furan skeleton, a thiophene skeleton, or an aromatic amine skeleton are preferred because they are stable and reliable. In addition, compounds having such skeletons have high hole transport properties and contribute to reducing the driving voltage.

[0243] <Hole transport layer> The hole transport layer 112 is a layer containing a hole transport material, and can use the hole transport materials exemplified as the material of the hole injection layer 111. The hole transport layer 112 has a function of transporting holes injected into the hole injection layer 111 to the light emitting layer 140, and therefore preferably has a HOMO level that is the same as or close to the HOMO level of the hole injection layer 111.

[0244] Also, 1×10 -6 cm 2 It is preferable that the material has a hole mobility of 1 / Vs or more. However, other materials may be used as long as they have a higher hole transporting property than electron transporting property. Note that the layer containing the material having a high hole transporting property may be a single layer or a stack of two or more layers made of the above-mentioned materials.

[0245] ≪Electron transport layer≫ The electron transport layer 118 has a function of transporting electrons injected from the other of the pair of electrodes (the electrode 101 or the electrode 102) through the electron injection layer 119 to the light-emitting layer 140. As the electron transport material, a material having a higher electron transporting property than a hole transporting property can be used. -6 cm 2 / Vs or more. Examples of compounds that can easily accept electrons (materials having electron transport properties) that can be used include π-electron deficient heteroaromatic ring compounds such as nitrogen-containing heteroaromatic ring compounds, metal complexes, and the like. Other specific examples include pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, triazine derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, phenanthroline derivatives, triazole derivatives, benzimidazole derivatives, and oxadiazole derivatives, all of which are listed as electron transport materials that can be used in the light-emitting layer 140. In addition, -6 cm 2 It is preferable that the electron-transporting layer is a material having an electron mobility of 100 / Vs or more. Note that any material other than the above may be used as the electron-transporting layer as long as it has a higher electron-transporting property than a hole-transporting property. The electron-transporting layer 118 may be a single layer or a stack of two or more layers made of the above materials.

[0246] In addition, metal complexes having heteroaromatic rings can be mentioned, for example, metal complexes having quinoline ligands, benzoquinoline ligands, oxazole ligands, or thiazole ligands.Specific examples include metal complexes having quinoline skeletons or benzoquinoline skeletons, such as tris(8-quinolinolato)aluminum(III) (abbreviation: Alq), tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviation: Almq3), bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq2), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (abbreviation: BAlq), and bis(8-quinolinolato)zinc(II) (abbreviation: Znq). In addition, metal complexes having oxazole or thiazole ligands, such as bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO) and bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ), can also be used.

[0247] Furthermore, a layer for controlling the movement of electron carriers may be provided between the electron transport layer 118 and the light emitting layer 140. This layer is made by adding a small amount of a substance with high electron trapping properties to a material with high electron transport properties as described above, and it becomes possible to adjust the carrier balance by suppressing the movement of electron carriers. This type of configuration is highly effective in suppressing problems (e.g., a decrease in device life) that occur when the electron transport properties of the electron transport material are significantly higher than the hole transport properties of the hole transport material.

[0248] ≪Electron injection layer≫ The material has a function of promoting electron injection by reducing the electron injection barrier at the interface between the electron injection layer 119 and the electrode 102, and for example, Group 1 metals, Group 2 metals, or oxides, halides, carbonates, etc., can be used. In addition, a composite material of the above-mentioned electron transport material and a material that exhibits electron donating properties can also be used. Examples of materials that exhibit electron donating properties include Group 1 metals, Group 2 metals, or oxides of these metals. Specific examples include lithium fluoride (LiF), sodium fluoride (NaF), cesium fluoride (CsF), calcium fluoride (CaF2), lithium oxide (LiO x ) or an alkaline earth metal, or a compound thereof, can be used. Also, a rare earth metal compound, such as erbium fluoride (ErF3), can be used. Also, an electride can be used for the electron injection layer 119. For example, the electride can be a substance in which a high concentration of electrons is added to a mixed oxide of calcium and aluminum. Also, a substance that can be used for the electron transport layer 118 can be used for the electron injection layer 119.

[0249] In addition, a composite material obtained by mixing an organic compound and an electron donor (donor) may be used for the electron injection layer 119. Such a composite material has excellent electron injection and electron transport properties because electrons are generated in the organic compound by the electron donor. In this case, the organic compound is preferably a material that is excellent in transporting the generated electrons, and specifically, for example, the above-mentioned substances constituting the electron transport layer 118 (metal complexes, heteroaromatic ring compounds, etc.) can be used. As the electron donor, any substance that exhibits electron donating properties to the organic compound may be used. Specifically, alkali metals, alkaline earth metals, and rare earth metals are preferred, and examples thereof include lithium, sodium, cesium, magnesium, calcium, erbium, and ytterbium. In addition, alkali metal oxides and alkaline earth metal oxides are preferred, and examples thereof include lithium oxide, calcium oxide, and barium oxide. In addition, a Lewis base such as magnesium oxide can also be used. In addition, an organic compound such as tetrathiafulvalene (abbreviation: TTF) can also be used.

[0250] The above-mentioned light-emitting layer, hole injection layer, hole transport layer, electron transport layer, and electron injection layer can be formed by a method such as a vapor deposition method (including a vacuum vapor deposition method), an inkjet method, a coating method, gravure printing, etc. In addition to the above-mentioned materials, the above-mentioned light-emitting layer, hole injection layer, hole transport layer, electron transport layer, and electron injection layer may be made of inorganic compounds such as quantum dots or polymer compounds (oligomers, dendrimers, polymers, etc.).

[0251] Quantum dots Quantum dots are semiconductor nanocrystals with sizes ranging from a few nm to a few tens of nm, with a size of 1×10 3 1×10 6 Each quantum dot is composed of about 100 atoms. Since quantum dots have an energy shift that depends on their size, even quantum dots composed of the same material have different emission wavelengths depending on their size. Therefore, the emission wavelength can be easily changed by changing the size of the quantum dots used.

[0252] In addition, quantum dots have a narrow peak width of the emission spectrum, so that light emission with good color purity can be obtained. Furthermore, the theoretical internal quantum efficiency of quantum dots is said to be nearly 100%, which is significantly higher than the 25% of organic compounds that exhibit fluorescent emission and is equivalent to organic compounds that exhibit phosphorescent emission. For this reason, by using quantum dots as a light-emitting material, a light-emitting element with high luminous efficiency can be obtained. Moreover, quantum dots, which are inorganic materials, are also excellent in their inherent stability, so that a light-emitting element that is preferable in terms of life can be obtained.

[0253] Examples of materials that can be used to form quantum dots include Group 14 elements, Group 15 elements, Group 16 elements, compounds consisting of multiple Group 14 elements, compounds of an element belonging to Groups 4 to 14 and a Group 16 element, compounds of a Group 2 element and a Group 16 element, compounds of a Group 13 element and a Group 15 element, compounds of a Group 13 element and a Group 17 element, compounds of a Group 14 element and a Group 15 element, compounds of a Group 11 element and a Group 17 element, iron oxides, titanium oxides, chalcogenide spinels, and semiconductor clusters.

[0254] Specifically, cadmium selenide, cadmium sulfide, cadmium telluride, zinc selenide, zinc oxide, zinc sulfide, zinc telluride, mercury sulfide, mercury selenide, mercury telluride, indium arsenide, indium phosphide, gallium arsenide, gallium phosphide, indium nitride, gallium nitride, indium antimonide, gallium antimonide, aluminum phosphide, aluminum arsenide, aluminum antimonide, lead selenide, lead telluride, lead sulfide, indium selenide, indium telluride Indium, indium sulfide, gallium selenide, arsenic sulfide, arsenic selenide, arsenic telluride, antimony sulfide, antimony selenide, antimony telluride, bismuth sulfide, bismuth selenide, bismuth telluride, silicon, silicon carbide, germanium, tin, selenium, tellurium, boron, carbon, phosphorus, boron nitride, boron phosphide, boron arsenide, aluminum nitride, aluminum sulfide, barium sulfide, barium selenide, barium telluride, calcium sulfide, calcium selenide, terbium calcium sulfide, beryllium sulfide, beryllium selenide, beryllium telluride, magnesium sulfide, magnesium selenide, germanium sulfide, germanium selenide, germanium telluride, tin sulfide, tin selenide, tin telluride, lead oxide, copper fluoride, copper chloride, copper bromide, copper iodide, copper oxide, copper selenide, nickel oxide, cobalt oxide, cobalt sulfide, iron oxide, iron sulfide, manganese oxide, molybdenum sulfide, vanadium oxide, tungsten oxide, tantalum oxide, titanium oxide, oxide Examples of the quantum dots include, but are not limited to, zirconium, silicon nitride, germanium nitride, aluminum oxide, barium titanate, compounds of selenium, zinc, and cadmium, compounds of indium, arsenic, and phosphorus, compounds of cadmium, selenium, and sulfur, compounds of cadmium, selenium, and tellurium, compounds of indium, gallium, and arsenic, compounds of indium, gallium, and selenium, compounds of indium, selenium, and sulfur, compounds of copper, indium, and sulfur, and combinations thereof. In addition, so-called alloy quantum dots, whose composition is expressed in any ratio, may be used. For example, alloy quantum dots of cadmium, selenium, and sulfur are one of the effective means for obtaining blue light emission, since the emission wavelength can be changed by changing the content ratio of the elements.

[0255] The quantum dot structure may be a core type, a core-shell type, a core-multishell type, or the like, and any of these may be used, but by covering the core and forming a shell with another inorganic material having a wider band gap, the effect of defects and dangling bonds present on the nanocrystal surface can be reduced. This significantly improves the quantum efficiency of light emission, so it is preferable to use core-shell or core-multishell quantum dots. Examples of shell materials include zinc sulfide and zinc oxide.

[0256] In addition, quantum dots have a high proportion of surface atoms, and therefore are highly reactive and prone to aggregation. For this reason, it is preferable that a protective agent is attached to the surface of the quantum dots or that a protective group is provided. By attaching the protective agent or providing the protective group, aggregation can be prevented and solubility in a solvent can be increased. It is also possible to reduce reactivity and improve electrical stability. Examples of protective agents (or protective groups) include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether; trialkyl phosphines such as tripropyl phosphine, tributyl phosphine, trihexyl phosphine, and trioctyl phosphine; polyoxyethylene alkyl phenyl ethers such as polyoxyethylene n-octyl phenyl ether and polyoxyethylene n-nonyl phenyl ether; tertiary amines such as tri(n-hexyl)amine, tri(n-octyl)amine, and tri(n-decyl)amine; and amines such as tripropyl phosphine oxide, tributyl phosphine oxide, trihexyl phosphine oxide, and tridecyl phosphine oxide. Examples of the organic phosphorus compounds include polyethylene glycol dilaurate, polyethylene glycol distearate, and other polyethylene glycol diesters; organic nitrogen compounds such as nitrogen-containing aromatic compounds such as pyridine, lutidine, collidine, and quinolines; aminoalkanes such as hexylamine, octylamine, decylamine, dodecylamine, tetradecylamine, hexadecylamine, and octadecylamine; dialkyl sulfides such as dibutyl sulfide; dialkyl sulfoxides such as dimethyl sulfoxide and dibutyl sulfoxide; organic sulfur compounds such as sulfur-containing aromatic compounds such as thiophene; higher fatty acids such as palmitic acid, stearic acid, and oleic acid; alcohols; sorbitan fatty acid esters; fatty acid-modified polyesters; tertiary amine-modified polyurethanes; and polyethyleneimines.

[0257] The smaller the size of the quantum dot, the larger the band gap becomes, so the size is adjusted appropriately to obtain light of the desired wavelength. As the size of the crystal becomes smaller, the emission of the quantum dot shifts to the blue side, that is, to the high energy side, so that the emission wavelength can be adjusted over the wavelength range of the ultraviolet, visible, and infrared regions of the spectrum by changing the size of the quantum dot. The size (diameter) of the quantum dot is usually in the range of 0.5 nm to 20 nm, preferably 1 nm to 10 nm. The narrower the size distribution of the quantum dot, the narrower the emission spectrum becomes, and light emission with good color purity can be obtained. The shape of the quantum dot is not particularly limited, and may be spherical, rod-shaped, disk-shaped, or other shapes. The quantum rod, which is a rod-shaped quantum dot, has the function of exhibiting light with directionality, so that a light-emitting element with better external quantum efficiency can be obtained by using the quantum rod as a light-emitting material.

[0258] In many organic EL devices, the luminescent material is dispersed in a host material to suppress concentration quenching of the luminescent material, thereby increasing the luminous efficiency. The host material must have a singlet excitation energy level or triplet excitation energy level higher than that of the luminescent material. In particular, when a blue phosphorescent material is used as the luminescent material, a host material that has a triplet excitation energy level higher than that and is excellent in terms of life is required, and its development is extremely difficult. Here, quantum dots can maintain luminous efficiency even when the luminescent layer is formed only from quantum dots without using a host material, so that a light-emitting element that is preferable in terms of life can be obtained in this respect as well. When the luminescent layer is formed only from quantum dots, it is preferable that the quantum dots have a core-shell structure (including a core-multishell structure).

[0259] When quantum dots are used as the light-emitting material of the light-emitting layer, the film thickness of the light-emitting layer is 3 nm to 100 nm, preferably 10 nm to 100 nm, and the content of quantum dots in the light-emitting layer is 1 to 100% by volume. However, it is preferable to form the light-emitting layer only with quantum dots. In addition, when forming a light-emitting layer in which the quantum dots are dispersed in a host as a light-emitting material, the quantum dots may be dispersed in a host material, or the host material and the quantum dots may be dissolved or dispersed in a suitable liquid medium and formed by a wet process (spin coating, casting, die coating, blade coating, roll coating, inkjet, printing, spray coating, curtain coating, Langmuir-Blodgett method, etc.). For a light-emitting layer using a phosphorescent light-emitting material, in addition to the above wet process, a vacuum deposition method may also be suitably used.

[0260] Examples of liquid media that can be used in the wet process include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, aromatic hydrocarbons such as toluene, xylene, mesitylene, and cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin, and dodecane, and organic solvents such as dimethylformamide (DMF) and dimethyl sulfoxide (DMSO).

[0261] The electrode 101 and the electrode 102 function as an anode or a cathode of a light-emitting element. The electrode 101 and the electrode 102 can be formed using a metal, an alloy, a conductive compound, or a mixture or stack of these materials.

[0262] One of the electrodes 101 and 102 is preferably made of a conductive material having a light reflecting function. Examples of the conductive material include aluminum (Al) and alloys containing Al. Examples of alloys containing Al include alloys containing Al and L (L represents one or more of titanium (Ti), neodymium (Nd), nickel (Ni), and lanthanum (La)), such as alloys containing Al and Ti, or alloys containing Al, Ni, and La. Aluminum has a low resistance value and a high light reflectance. In addition, aluminum is abundant in the earth's crust and is inexpensive, so that the manufacturing cost of the light-emitting element can be reduced by using aluminum. In addition, an alloy containing silver (Ag) or Ag and N (N represents one or more of yttrium (Y), Nd, magnesium (Mg), ytterbium (Yb), Al, Ti, gallium (Ga), zinc (Zn), indium (In), tungsten (W), manganese (Mn), tin (Sn), iron (Fe), Ni, copper (Cu), palladium (Pd), iridium (Ir), or gold (Au)) may be used. Examples of the alloy containing silver include an alloy containing silver, palladium, and copper, an alloy containing silver and copper, an alloy containing silver and magnesium, an alloy containing silver and nickel, an alloy containing silver and gold, and an alloy containing silver and ytterbium. In addition, transition metals such as tungsten, chromium (Cr), molybdenum (Mo), copper, and titanium can be used.

[0263] Furthermore, light emitted 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 made of a conductive material that has a light-transmitting function. The conductive material has a visible light transmittance of 40% or more and 100% or less, preferably 60% or more and 100% or less, and a resistivity of 1×10 -2 Examples include conductive materials with a resistance of Ω·cm or less.

[0264] The electrodes 101 and 102 may be made of a conductive material that has both a light transmitting and light reflecting function. The conductive material has a visible light reflectance of 20% to 80%, preferably 40% to 70%, and a resistivity of 1×10 -2 Examples of the conductive material include a material having a resistivity of Ω·cm or less. For example, the conductive material can be formed by using one or more conductive metals, alloys, conductive compounds, etc. Specifically, for example, metal oxides such as indium tin oxide (hereinafter, ITO), indium tin oxide containing silicon or silicon oxide (abbreviated as ITSO), indium oxide-zinc oxide, indium oxide-tin oxide containing titanium, indium-titanium oxide, indium oxide containing tungsten oxide and zinc oxide, etc. can be used. In addition, a metal thin film having a thickness of about 1 nm or more and 30 nm or less that transmits light can be used. As the metal, for example, Ag, or an alloy such as Ag and Al, Ag and Mg, Ag and Au, Ag and Yb, etc. can be used.

[0265] In this specification and the like, the material having a function of transmitting light may be any material that has a function of transmitting visible light and has electrical conductivity, and includes, for example, oxide conductors such as ITO as described above, as well as oxide semiconductors and organic conductors containing organic substances. Examples of organic conductors containing organic substances include composite materials obtained by mixing an organic compound with an electron donor, and composite materials obtained by mixing an organic compound with an electron acceptor. Inorganic carbon-based materials such as graphene may also be used. The resistivity of the material is preferably 1×10 5 Ω cm or less, more preferably 1×10 4 Ω·cm or less.

[0266] Alternatively, one or both of the electrode 101 and the electrode 102 may be formed by stacking a plurality of the above materials.

[0267] In addition, in order to improve the light extraction efficiency, a material having a higher refractive index than an electrode having a function of transmitting light may be formed in contact with the electrode. Such a material may be a material having a function of transmitting visible light, and may be a material having or not having electrical conductivity. For example, in addition to the oxide conductor as described above, an oxide semiconductor and an organic material may be mentioned. As the organic material, for example, the materials exemplified in the light-emitting layer, the hole injection layer, the hole transport layer, the electron transport layer, or the electron injection layer may be mentioned. In addition, an inorganic carbon-based material or a metal thin film having a thickness of several nm to several tens of nm may be used, and a plurality of layers may be stacked.

[0268] When the electrode 101 or the electrode 102 functions as a cathode, it is preferable that the electrode 101 or 102 has a material with a small work function (3.8 eV or less). For example, elements belonging to Group 1 or 2 of the periodic table (alkali metals such as lithium, sodium, and cesium, alkaline earth metals such as calcium and strontium, magnesium, etc.), alloys containing these elements (for example, Ag and Mg, Al and Li), rare earth metals such as europium (Eu) and Yb, alloys containing these rare earth metals, alloys containing aluminum and silver, etc. can be used.

[0269] 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 more).

[0270] The electrodes 101 and 102 may be a laminate of a conductive material having a light reflecting function and a conductive material having a light transmitting function. In that case, the electrodes 101 and 102 are preferable because they can have a function of adjusting the optical distance so that light of a desired wavelength from each light emitting layer can be resonated and the light of the desired wavelength can be intensified.

[0271] The electrodes 101 and 102 can be formed by any suitable method, such as sputtering, vapor deposition, printing, coating, MBE (Molecular Beam Epitaxy), CVD, pulsed laser deposition, or ALD (Atomic Layer Deposition).

[0272] <Substrate> The light-emitting element according to one embodiment of the present invention may be fabricated over a substrate made of glass, plastic, or the like. The order of fabrication on the substrate may be from the electrode 101 side or from the electrode 102 side.

[0273] As a substrate on which a light-emitting element according to one embodiment of the present invention can be formed, for example, glass, quartz, or plastic can be used. A flexible substrate can also be used. A flexible substrate is a bendable (flexible) substrate, and examples of such substrates include plastic substrates made of polycarbonate or polyarylate. Films, inorganic deposition films, and the like can also be used. Any other substrate may be used as long as it functions as a support in the manufacturing process of the light-emitting element and the optical element. Alternatively, any substrate may be used as long as it has a function of protecting the light-emitting element and the optical element.

[0274] For example, in the present specification and the like, a light-emitting element can be formed using various substrates. The type of substrate is not particularly limited. Examples of the substrate include a semiconductor substrate (e.g., 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 having stainless steel foil, a tungsten substrate, a substrate having tungsten foil, a flexible substrate, a laminated film, paper containing a fibrous material, or a base film. Examples of glass substrates include barium borosilicate glass, aluminoborosilicate glass, or soda lime glass. Examples of flexible substrates, laminated films, base films, and the like include the following. For example, there are plastics typified by polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), and polytetrafluoroethylene (PTFE). Alternatively, there are resins such as acrylic. Alternatively, there are polypropylene, polyester, polyvinyl fluoride, or polyvinyl chloride. Alternatively, for example, there may be polyamide, polyimide, aramid, epoxy, an inorganic vapor deposition film, or paper.

[0275] Alternatively, a flexible substrate may be used as the substrate, and the light-emitting element may be formed directly on the flexible substrate. Alternatively, a peeling layer may be provided between the substrate and the light-emitting element. The peeling layer can be used to separate the light-emitting element from the substrate after a part or all of the light-emitting element is completed thereon, and transfer it to another substrate. In this case, the light-emitting element can be transferred to a substrate having poor heat resistance or a flexible substrate. For the above-mentioned peeling layer, for example, a laminated structure of inorganic films of a tungsten film and a silicon oxide film, or a structure in which a resin film such as polyimide is formed on a substrate, can be used.

[0276] That is, a light-emitting element may be formed using a certain substrate, and then the light-emitting element may be transferred to another substrate, and the light-emitting element may be disposed on the other substrate. In addition to the above-mentioned substrates, examples of the substrate onto which the light-emitting element may be transferred include a cellophane substrate, a stone substrate, a wood substrate, a cloth substrate (including natural fibers (silk, cotton, hemp), synthetic fibers (nylon, polyurethane, polyester), or regenerated fibers (acetate, cupra, rayon, regenerated polyester), etc.), a leather substrate, or a rubber substrate. By using these substrates, a light-emitting element that is not easily broken, has high heat resistance, is lightweight, or is thin.

[0277] Also, for example, a field effect transistor (FET) may be formed on the above-mentioned substrate, and the light emitting element 150 may be fabricated on an electrode electrically connected to the FET. This makes it possible to fabricate an active matrix display device in which the driving of the light emitting element 150 is controlled by the FET.

[0278] The structure described in this embodiment mode can be used in appropriate combination with other embodiment modes.

[0279] (Embodiment 4) In this embodiment, a light-emitting element having a different structure from that of the light-emitting element shown in Embodiment 3 will be described below with reference to Fig. 2. Note that in Fig. 2, parts having the same functions as those shown in Fig. 1(A) may be given the same hatch pattern and the reference numerals may be omitted. Also, parts having the same functions may be given the same reference numerals and detailed description thereof may be omitted.

[0280] <Light-emitting element configuration example 2> FIG. 2 is a schematic cross-sectional view of the light-emitting element 250. As shown in FIG.

[0281] The light-emitting element 250 shown in FIG. 2 has a plurality of light-emitting units (light-emitting unit 106 and light-emitting unit 108) between a pair of electrodes (electrode 101 and electrode 102). Any one of the plurality of light-emitting units preferably has a structure similar to that of the EL layer 100 shown in FIG. 1(A). In other words, the light-emitting element 150 shown in FIG. 1(A) preferably has one light-emitting unit, and the light-emitting element 250 preferably has a plurality of light-emitting units. Note that, in the light-emitting element 250, the electrode 101 functions as an anode and the electrode 102 functions as a cathode in the following description, but the structure of the light-emitting element 250 may be reversed.

[0282] 2, the light-emitting unit 106 and the light-emitting unit 108 are stacked, and a charge generation layer 115 is provided between the light-emitting unit 106 and the light-emitting unit 108. The light-emitting unit 106 and the light-emitting unit 108 may have the same structure or different structures. For example, it is preferable that the light-emitting unit 108 has the same structure as the EL layer 100.

[0283] The light-emitting element 250 includes a light-emitting layer 120 and a light-emitting layer 170. The light-emitting unit 106 includes, in addition to the light-emitting layer 170, a hole injection layer 111, a hole transport layer 112, an electron transport layer 113, and an electron injection layer 114. The light-emitting unit 108 includes, in addition to the light-emitting layer 120, a hole injection layer 116, a hole transport layer 117, an electron transport layer 118, and an electron injection layer 119.

[0284] The light-emitting element 250 may contain an organometallic complex according to one embodiment of the present invention in any layer of the light-emitting unit 106 or the light-emitting unit 108. Note that the layer containing the organic compound is preferably the light-emitting layer 120 or the light-emitting layer 170.

[0285] The charge generation layer 115 may be a structure in which an acceptor substance that is an electron acceptor is added to a hole transport material, or a structure in which a donor substance that is an electron donor is added to an electron transport material, or a structure in which both of these structures are laminated.

[0286] When the charge generation layer 115 contains a composite material of an organic compound and an acceptor substance, the composite material may be the composite material that can be used for the hole injection layer 111 described in Embodiment 3. As the organic compound, various compounds such as aromatic amine compounds, carbazole compounds, aromatic hydrocarbons, and polymer compounds (oligomers, dendrimers, polymers, etc.) can be used. Note that the organic compound is an organic compound having a hole mobility of 1×10 -6 cm 2 / Vs or more is preferably applied. However, other materials may be used as long as they have a higher transportability of holes than electrons. A composite material of an organic compound and an acceptor material has excellent carrier injection and carrier transport properties, and therefore can realize low-voltage driving and low-current driving. When the anode side surface of the light-emitting unit is in contact with the charge generation layer 115, the charge generation layer 115 can also play the role of the hole injection layer or hole transport layer of the light-emitting unit, so that the light-emitting unit may not have a hole injection layer or hole transport layer. Alternatively, when the cathode side surface of the light-emitting unit is in contact with the charge generation layer 115, the charge generation layer 115 can also play the role of the electron injection layer or electron transport layer of the light-emitting unit, so that the light-emitting unit may not have an electron injection layer or electron transport layer.

[0287] The charge generation layer 115 may be formed as a laminated structure in which a layer containing a composite material of an organic compound and an acceptor substance is combined with a layer composed of another material. For example, the charge generation layer 115 may be formed by combining a layer containing a composite material of an organic compound and an acceptor substance with a layer containing a compound selected from electron donor substances and a compound with high electron transport properties. Alternatively, the charge generation layer 115 may be formed by combining a layer containing a composite material of an organic compound and an acceptor substance with a layer containing a transparent conductive film.

[0288] Charge generation layer 115 sandwiched between light-emitting unit 106 and light-emitting unit 108 may be any layer that injects electrons into one light-emitting unit and injects holes into the other light-emitting unit when a voltage is applied between electrode 101 and electrode 102. For example, in FIG. 2, when a voltage is applied so that the potential of electrode 101 is higher than the potential of electrode 102, charge generation layer 115 injects electrons into light-emitting unit 106 and injects holes into light-emitting unit 108.

[0289] From the viewpoint of light extraction efficiency, the charge generation layer 115 is preferably transparent to visible light (specifically, the visible light transmittance of the charge generation layer 115 is 40% or more). The charge generation layer 115 functions even if it has a lower electrical conductivity than the pair of electrodes (electrodes 101 and 102).

[0290] By forming the charge generating layer 115 using the above-mentioned materials, it is possible to suppress an increase in driving voltage when a light emitting layer is laminated.

[0291] 2, a light-emitting element having two light-emitting units is described, but the same can be applied to a light-emitting element having three or more light-emitting units stacked together. As shown in the light-emitting element 250, by disposing a plurality of light-emitting units between a pair of electrodes and separating them with a charge generating layer, a light-emitting element that can emit light with high luminance while keeping the current density low and has a long life can be realized. In addition, a light-emitting element with low power consumption can be realized.

[0292] In each of the above configurations, the light emitting colors of the guest materials used in the light emitting units 106 and 108 may be the same or different. When the light emitting units 106 and 108 have guest materials that have the function of emitting light of the same color, the light emitting element 250 is a light emitting element that exhibits high light emission luminance at a small current value, which is preferable. When the light emitting units 106 and 108 have guest materials that have the function of emitting light of different colors, the light emitting element 250 is a light emitting element that exhibits multicolor emission, which is preferable. In this case, by using a plurality of light emitting materials with different emission wavelengths in either one or both of the light emitting layers 120 and 170, the emission spectrum of the light emitting element 250 is light in which light having different emission peaks is synthesized, and therefore the emission spectrum has at least two maximum values.

[0293] The above-mentioned configuration is also suitable for obtaining white light emission. White light emission can be obtained by making the light of the light-emitting layer 120 and the light-emitting layer 170 complementary to each other. In particular, it is suitable to select a guest material that will produce white light emission with high color rendering properties or light emission having at least red, green, and blue colors.

[0294] In addition, in the case of a light-emitting element having three or more stacked light-emitting units, the light-emitting colors of the guest materials used in the light-emitting units may be the same or different from each other. In the case of a light-emitting element having a plurality of light-emitting units that emit the same color, the plurality of light-emitting units can emit light with high intensity at a small current value. Such a configuration can be suitably used for adjusting the light-emitting color. In particular, it is suitable for the case of using guest materials that have different light-emitting efficiencies and emit different light colors. For example, in the case of a light-emitting element having three layers of light-emitting units, the light-emitting intensity of the fluorescent emission and the phosphorescent emission can be adjusted by using two layers of light-emitting units having a fluorescent material of the same color and one layer of a light-emitting unit having a phosphorescent material that emits a different light color from the fluorescent material. That is, the intensity of the light-emitting color can be adjusted by the number of light-emitting units.

[0295] In the case of such a light-emitting element having two layers of fluorescent light-emitting units and one layer of phosphorescent light-emitting unit, a light-emitting element containing two layers of light-emitting units containing a blue fluorescent material and one layer of light-emitting unit containing a yellow phosphorescent material, a light-emitting element having two layers of light-emitting units containing a blue fluorescent material and one layer of light-emitting layer unit containing a red phosphorescent material and a green phosphorescent material, or a light-emitting element having two layers of light-emitting units containing a blue fluorescent material and one layer of light-emitting layer unit containing a red phosphorescent material, a yellow phosphorescent material and a green phosphorescent material is preferable because white light can be emitted efficiently.

[0296] Also, at least one of the light-emitting layer 120 or the light-emitting layer 170 may be further divided into layers, and each divided layer may contain a different light-emitting material. That is, at least one of the light-emitting layer 120 or the light-emitting layer 170 may be configured with two or more layers. For example, when the first light-emitting layer and the second light-emitting layer are laminated in order from the hole transport layer side to form the light-emitting layer, a material having hole transport properties may be used as the host material of the first light-emitting layer, and a material having electron transport properties may be used as the host material of the second light-emitting layer. In this case, the light-emitting materials of the first light-emitting layer and the second light-emitting layer may be the same material or different materials, and may be materials having the function of emitting light of the same color or materials having the function of emitting light of different colors. By using a configuration having a plurality of light-emitting materials having the function of emitting light of different colors, it is also possible to obtain white light emission with high color rendering consisting of three primary colors or four or more colors of light emission.

[0297] It is also preferable that the light-emitting layer of the light-emitting unit 108 contains a phosphorescent compound. By applying an organometallic complex according to one embodiment of the present invention to at least one of the multiple units, a light-emitting element with high emission efficiency and reliability can be provided.

[0298] Note that this embodiment mode can be appropriately combined with other embodiment modes.

[0299] (Embodiment 5) In this embodiment mode, a light-emitting device using the light-emitting elements described in Embodiment Modes 3 and 4 will be described with reference to FIGS.

[0300] Fig. 3(A) is a top view showing a light-emitting device, and Fig. 3(B) is a cross-sectional view taken along lines AB and CD in Fig. 3(A). This light-emitting device includes a driver circuit section (source side driver circuit) 601, a pixel section 602, and a driver circuit section (gate side driver circuit) 603, all of which are shown by dotted lines to control the light emission of the light-emitting element. In addition, 604 is a sealing substrate, 625 is a desiccant, and 605 is a sealant, and the inside surrounded by the sealant 605 is a space 607.

[0301] The lead wiring 608 is a wiring for transmitting signals input to the source side driving circuit 601 and the gate side driving circuit 603, and receives a video signal, a clock signal, a start signal, a reset signal, and the like from an FPC (flexible printed circuit) 609 serving as an external input terminal. Although only an FPC is shown here, a printed wiring board (PWB: Printed Wiring Board) may be attached to this FPC. In this specification, the light emitting device includes not only the light emitting device itself, but also a state in which an FPC or PWB is attached to it.

[0302] Next, a cross-sectional structure of the light-emitting device will be described with reference to Fig. 3(B). A driver circuit section and a pixel section are formed on an element substrate 610, and here, a source side driver circuit 601, which is the driver circuit section, and one pixel in a pixel section 602 are shown.

[0303] The source side driver circuit 601 is formed as a CMOS circuit combining an n-channel TFT 623 and a p-channel TFT 624. The driver circuit may be formed of various CMOS circuits, PMOS circuits, and NMOS circuits. In this embodiment, a driver integrated type in which the driver circuit is formed on the substrate is shown, but this is not necessarily required, and the driver circuit may be formed externally instead of on the substrate.

[0304] The pixel section 602 is formed of pixels including a switching TFT 611, a current control TFT 612, and a first electrode 613 electrically connected to the drain of the switching TFT 611. An insulator 614 is formed so as to cover an end of the first electrode 613. The insulator 614 can be formed by using a positive type photosensitive resin film.

[0305] In order to improve the coverage of the film formed on the insulator 614, a surface having a curvature is formed at the upper or lower end of the insulator 614. For example, when photosensitive acrylic is used as the material of the insulator 614, it is preferable to provide a curved surface only at the upper end of the insulator 614. The radius of curvature of the curved surface is preferably 0.2 μm or more and 0.3 μm or less. In addition, either a negative type or a positive type photosensitive material can be used as the insulator 614.

[0306] An EL layer 616 and a second electrode 617 are formed on the first electrode 613. Here, it is desirable to use a material with a large work function as the material used for the first electrode 613 that functions as an anode. For example, in addition to a single layer film such as an ITO film, an indium tin oxide film containing silicon, an indium oxide film containing 2 wt% to 20 wt% zinc oxide, a titanium nitride film, a chromium film, a tungsten film, a Zn film, or a Pt film, a laminated film of a film mainly composed of titanium nitride and aluminum, or a three-layer structure of a titanium nitride film, a film mainly composed of aluminum, and a titanium nitride film can be used. Note that a laminated structure provides low resistance as wiring, good ohmic contact, and can further function as an anode.

[0307] The EL layer 616 is formed by various methods such as a deposition method using a deposition mask, an inkjet method, a spin coating method, etc. The material constituting the EL layer 616 may be a low molecular weight compound or a high molecular weight compound (including an oligomer and a dendrimer).

[0308] Furthermore, the second electrode 617 formed on the EL layer 616 and functioning as a cathode is preferably made of a material having a small work function (Al, Mg, Li, Ca, or alloys or compounds thereof, such as MgAg, MgIn, and AlLi). When light generated in the EL layer 616 is transmitted through the second electrode 617, the second electrode 617 is preferably made of a laminate of a thin metal thin film and a transparent conductive film (ITO, indium oxide containing 2 wt% to 20 wt% zinc oxide, indium tin oxide containing silicon, zinc oxide (ZnO), or the like).

[0309] Note that a light-emitting element 618 is formed by the first electrode 613, the EL layer 616, and the second electrode 617. The light-emitting element 618 is preferably a light-emitting element having the structures of Embodiments 3 and 4. Note that a pixel portion is formed with a plurality of light-emitting elements, but the light-emitting device in this embodiment may include both light-emitting elements having the structures described in Embodiments 3 and 4 and light-emitting elements having other structures.

[0310] Furthermore, by bonding the sealing substrate 604 to the element substrate 610 with a sealant 605, a structure is formed in which 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 may be filled with an inert gas (nitrogen, argon, etc.), or with a resin or a desiccant, or both.

[0311] It is preferable to use epoxy resin or glass frit for the sealing material 605. It is also preferable that these materials are as moisture and oxygen impermeable as possible. In addition to glass and quartz substrates, materials that can be used for the sealing substrate 604 include plastic substrates made of FRP (Fiber Reinforced Plastics), PVF (Polyvinyl Fluoride), polyester, acrylic, etc.

[0312] In the above manner, a light-emitting device using the light-emitting element described in any of Embodiments 3 and 4 can be obtained.

[0313] <Light-emitting device configuration example 1> FIG. 4 shows, as an example of a display device, an example of a light-emitting device in which a light-emitting element that emits white light is formed and a colored layer (color filter) is formed.

[0314] Figure 4(A) shows 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 sealing material 1032, etc.

[0315] In addition, in Fig. 4(A) and Fig. 4(B), colored layers (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B) are provided on a transparent base material 1033. A black layer (black matrix) 1035 may be further provided. The transparent base material 1033 provided with the colored layers and the black layer is aligned and fixed to the substrate 1001. The colored layers and the black layer are covered with an overcoat layer 1036. In addition, in Fig. 4(A), there are light-emitting layers from which light does not pass through the colored layers and goes out to the outside, and light-emitting layers from which light passes through the colored layers of each color and goes out to the outside. The light that does not pass through the colored layers is white, and the light that passes through the colored layers is red, blue, and green, so that an image can be expressed by four color pixels.

[0316] 4B shows an example in which a red colored layer 1034R, a green colored layer 1034G, and a blue colored layer 1034B are formed between the gate insulating film 1003 and the first interlayer insulating film 1020. As shown in FIG. 4B, the colored layers may be provided between the substrate 1001 and the sealing substrate 1031.

[0317] Furthermore, the light-emitting device described above has a structure (bottom emission type) in which light is extracted from the substrate 1001 side on which the TFT is formed, but it may also be a light-emitting device with a structure (top emission type) in which light is extracted from the sealing substrate 1031 side.

[0318] <Configuration Example 2 of Light Emitting Device> A cross-sectional view of a top-emission type light-emitting device is shown in FIG. 5. In this case, a substrate that does not transmit light can be used as the substrate 1001. The process is performed in the same manner as for a bottom-emission type light-emitting device until a connection electrode that connects the TFT and the anode of the light-emitting element is formed. Then, a third interlayer insulating film 1037 is formed to cover the electrode 1022. This insulating film may also serve to planarize the surface. The third interlayer insulating film 1037 can be formed using the same material as the second interlayer insulating film 1021, or various other materials.

[0319] The first lower electrode 1025W, the lower electrode 1025R, the lower electrode 1025G, and the lower electrode 1025B of the light-emitting element are anodes here, but may be cathodes. In addition, in the case of a top-emission type light-emitting device as shown in FIG. 5, the lower electrode 1025W, the lower electrode 1025R, the lower electrode 1025G, and the lower electrode 1025B are preferably reflective electrodes. Note that the second electrode 1029 preferably has a function of reflecting light and a function of transmitting light. In addition, it is preferable that a microcavity structure is applied between the second electrode 1029 and the lower electrode 1025W, the lower electrode 1025R, the lower electrode 1025G, and the lower electrode 1025B to have a function of amplifying light of a specific wavelength. The EL layer 1028 is configured as described in the third and fourth embodiments, and has an element structure that can emit white light.

[0320] 4(A), 4(B), and 5, the configuration of the EL layer that can emit white light may be realized by using multiple light-emitting layers, multiple light-emitting units, etc. Note that the configuration for obtaining white light emission is not limited to these.

[0321] In the top emission structure as shown in Fig. 5, sealing can be performed with a sealing substrate 1031 provided with colored layers (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B). The sealing substrate 1031 may be provided with a black layer (black matrix) 1030 so as to be positioned between pixels. The colored layers (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B) and the black layer (black matrix) 1030 may be covered with an overcoat layer. Note that a light-transmitting substrate is used as the sealing substrate 1031.

[0322] Although an example of full-color display using four colors, red, green, blue, and white, is shown here, there is no particular limitation, and full-color display using three colors, red, green, and blue, or full-color display using four colors, red, green, blue, and yellow, may also be used.

[0323] In the above manner, a light-emitting device using the light-emitting element described in any of Embodiments 3 and 4 can be obtained.

[0324] Note that this embodiment mode can be appropriately combined with other embodiment modes.

[0325] (Embodiment 6) In this embodiment, an electronic device according to one embodiment of the present invention will be described.

[0326] Since one embodiment of the present invention is a light-emitting element using an organic electroluminescent device, an electronic device having a flat surface, high emission efficiency, and high reliability can be manufactured. In addition, one embodiment of the present invention allows a highly reliable electronic device to be manufactured. In addition, by using an organic compound according to one embodiment of the present invention in the electronic device, a highly reliable electronic device having high emission efficiency can be manufactured.

[0327] Examples of electronic devices include television sets, desktop or notebook personal computers, computer monitors, digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, personal digital assistants, audio playback devices, and large game machines such as pachinko machines.

[0328] A portable information terminal 900 shown in FIGS. 6A and 6B includes a housing 901, a housing 902, a display portion 903, a hinge portion 905, and the like.

[0329] Housings 901 and 902 are connected by a hinge portion 905. The mobile information terminal 900 can be unfolded from a folded state (FIG. 6(A)) as shown in FIG. 6(B). This allows for excellent portability when carried around, and excellent visibility due to the large display area when in use.

[0330] A portable information terminal 900 has a flexible display unit 903 that spans a housing 901 and a housing 902 that are connected by a hinge unit 905 .

[0331] A light-emitting device manufactured according to one embodiment of the present invention can be used for the display portion 903. In this way, a highly reliable portable information terminal can be manufactured.

[0332] The display unit 903 can display at least one of document information, still images, and moving images, etc. When document information is displayed on the display unit, the portable information terminal 900 can be used as an electronic book terminal.

[0333] When the mobile information terminal 900 is unfolded, the display portion 903 is held in a state in which the radius of curvature is large. For example, the display portion 903 is held including a curved portion with a radius of curvature of 1 mm to 50 mm, preferably 5 mm to 30 mm. In part of the display portion 903, pixels are continuously arranged from the housing 901 to the housing 902, and a curved display can be performed.

[0334] The display unit 903 functions as a touch panel and can be operated with a finger, a stylus, or the like.

[0335] The display unit 903 is preferably configured as a single flexible display. This allows continuous display without interruption between the housing 901 and the housing 902. Note that each of the housing 901 and the housing 902 may be provided with a display.

[0336] It is preferable that the hinge section 905 has a locking mechanism so that the angle between the housing 901 and the housing 902 does not become larger than a predetermined angle when the mobile information terminal 900 is unfolded. For example, the angle at which the lock is applied (the housing does not open any further) is preferably equal to or greater than 90 degrees and less than 180 degrees, and typically can be 90 degrees, 120 degrees, 135 degrees, 150 degrees, or 175 degrees. This can improve the convenience, safety, and reliability of the mobile information terminal 900.

[0337] If the hinge section 905 has a locking mechanism, excessive force is not applied to the display section 903, and damage to the display section 903 can be prevented. Therefore, a highly reliable portable information terminal can be realized.

[0338] The housing 901 and the housing 902 may each include a power button, an operation button, an external connection port, a speaker, a microphone, and the like.

[0339] Either the housing 901 or the housing 902 is provided with a wireless communication module, and data can be transmitted and received via a computer network such as the Internet, a LAN (Local Area Network), or Wi-Fi (registered trademark).

[0340] A portable information terminal 910 shown in FIG. 6C 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.

[0341] A light-emitting device manufactured according to one embodiment of the present invention can be used for the display portion 912. This enables portable information terminals to be manufactured with high yield.

[0342] The mobile information terminal 910 has a touch sensor on a display unit 912. Any operation, such as making a call or inputting characters, can be performed by touching the display unit 912 with a finger, a stylus, or the like.

[0343] In addition, by operating the operation button 913, it is possible to turn the power on and off, and to switch the type of image displayed on the display unit 912. For example, it is possible to switch from a mail creation screen to a main menu screen.

[0344] Furthermore, by providing a detection device such as a gyro sensor or an acceleration sensor inside the mobile information terminal 910, the orientation (portrait or landscape) of the mobile information terminal 910 can be determined and the orientation of the screen display on the display unit 912 can be automatically switched. The orientation of the screen display can also be switched by touching the display unit 912, by operating the operation button 913, or by voice input using the microphone 916.

[0345] The mobile information terminal 910 has one or more functions selected from, for example, a telephone, a notebook, or an information viewing device. Specifically, it can be used as a smartphone. The mobile information terminal 910 can execute various applications such as mobile phone, e-mail, text viewing and creation, music playback, video playback, Internet communication, and games.

[0346] 6D includes a housing 921, a display portion 922, an operation button 923, a shutter button 924, and the like.

[0347] A light-emitting device manufactured according to one embodiment of the present invention can be used for the display portion 922. In this way, a highly reliable camera can be manufactured.

[0348] Here, camera 920 is configured such that lens 926 can be detached from housing 921 and replaced, but lens 926 and housing 921 may be integrated.

[0349] The camera 920 can capture still images or moving images by pressing a shutter button 924. The display unit 922 also has a function as a touch panel, and an image can also be captured by touching the display unit 922.

[0350] The camera 920 may be equipped with a strobe device, a viewfinder, and the like, or these may be incorporated into the housing 921.

[0351] 7A is a perspective view showing a wristwatch-type portable information terminal 9200, and FIG. 7B is a perspective view showing a wristwatch-type portable information terminal 9201. FIG.

[0352] The portable information terminal 9200 shown in FIG. 7A can execute various applications such as mobile phone, e-mail, text browsing and creation, music playback, Internet communication, and computer games. The display surface of the display unit 9001 is curved, and display can be performed along the curved display surface. The portable information terminal 9200 can execute short-distance wireless communication according to a communication standard. For example, hands-free conversation can be performed by mutual communication with a headset capable of wireless communication. The portable information terminal 9200 has a connection terminal 9006, and can directly exchange data with another information terminal via a connector. Charging can also be performed via the connection terminal 9006. Note that charging may be performed by wireless power supply without using the connection terminal 9006.

[0353] 7(A), the portable information terminal 9201 shown in Fig. 7(B) does not have a curved display surface of the display portion 9001. Also, the outer shape of the display portion of the portable information terminal 9201 is non-rectangular (circular in Fig. 7(B)).

[0354] 7(C) to 7(E) are perspective views showing a foldable portable information terminal 9202. Note that Fig. 7(C) is a perspective view of the portable information terminal 9202 in an unfolded state, Fig. 7(D) is a perspective view of the portable information terminal 9202 in the process of changing from one of the unfolded state and the folded state to the other, and Fig. 7(E) is a perspective view of the portable information terminal 9202 in a folded state.

[0355] The portable information terminal 9202 has excellent portability in a folded state, and has excellent display visibility due to a seamless wide display area in an unfolded state. A display portion 9001 of the portable information terminal 9202 is supported by three housings 9000 connected by hinges 9055. The portable information terminal 9202 can be reversibly transformed from an unfolded state to a folded state by bending the two housings 9000 via the hinges 9055. For example, the portable information terminal 9202 can be bent with a curvature radius of 1 mm or more and 150 mm or less.

[0356] FIG. 8(A) is a schematic diagram showing an example of a cleaning robot.

[0357] The cleaning robot 5100 has a display 5101 arranged on the top surface, a plurality of cameras 5102 arranged on the side surface, a brush 5103, and an operation button 5104. Although not shown, the bottom surface of the cleaning robot 5100 is provided with tires, a suction port, and the like. The cleaning robot 5100 also has various sensors such as an infrared sensor, an ultrasonic sensor, an acceleration sensor, a piezoelectric sensor, an optical sensor, and a gyro sensor. The cleaning robot 5100 also has wireless communication means.

[0358] The cleaning robot 5100 can move by itself, detect dirt 5120, and suck up the dirt from a suction port provided on the bottom surface.

[0359] In addition, the cleaning robot 5100 can analyze the image captured by the camera 5102 and determine the presence or absence of obstacles such as walls, furniture, steps, etc. Furthermore, when an object that may become entangled in the brush 5103, such as a wire, is detected by image analysis, the rotation of the brush 5103 can be stopped.

[0360] The remaining battery level, the amount of sucked up dirt, etc. can be displayed on the display 5101. The route traveled by the cleaning robot 5100 may be displayed on the display 5101. The display 5101 may be a touch panel, and an operation button 5104 may be provided on the display 5101.

[0361] The cleaning robot 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 cleaning robot 5100 can know the state of the room even when he or she is away from home. Also, the display on the display 5101 can be confirmed on a portable electronic device such as a smartphone.

[0362] The light-emitting device according to one embodiment of the present invention can be used for the display 5101 .

[0363] The robot 2100 shown in FIG. 8(B) includes a computing device 2110, an illuminance sensor 2101, a microphone 2102, an upper camera 2103, a speaker 2104, a display 2105, a lower camera 2106, an obstacle sensor 2107, and a movement mechanism 2108.

[0364] The microphone 2102 has a function of detecting the user's voice, environmental sounds, etc. The speaker 2104 has a function of emitting sound. The robot 2100 can communicate with the user using the microphone 2102 and the speaker 2104.

[0365] The display 2105 has a function of displaying various information. The robot 2100 can display information desired by the user on the display 2105. The display 2105 may be equipped with a touch panel. The display 2105 may also be a removable information terminal, and by installing it in a fixed position on the robot 2100, charging and data transfer are possible.

[0366] The upper camera 2103 and the lower camera 2106 have a function of capturing images of the surroundings of the robot 2100. In addition, the obstacle sensor 2107 can detect the presence or absence of an obstacle in the direction of travel when the robot 2100 moves forward using the moving mechanism 2108. The robot 2100 can recognize the surrounding environment and move safely using the upper camera 2103, the lower camera 2106, and the obstacle sensor 2107.

[0367] The light-emitting device according to one embodiment of the present invention can be used for the display 2105 .

[0368] FIG. 8C is a diagram showing an example of a goggle-type display. The goggle-type display has, for example, a housing 5000, a display unit 5001, a speaker 5003, an LED lamp 5004, operation keys 5005 (including a power switch or an operation switch), a connection terminal 5006, a sensor 5007 (including a function to measure force, displacement, position, speed, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared light), a microphone 5008, a second display unit 5002, a support unit 5012, earphones 5013, etc.

[0369] 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 .

[0370] 9(A) and (B) show a foldable mobile information terminal 5150. The foldable mobile information terminal 5150 has a housing 5151, a display area 5152, and a bending portion 5153. Fig. 9(A) shows the mobile information terminal 5150 in an unfolded state. Fig. 9(B) shows the mobile information terminal 5150 in a folded state. Although the mobile information terminal 5150 has a large display area 5152, it is compact and highly portable when folded.

[0371] Display area 5152 can be folded in half by bending portion 5153. Bending portion 5153 is composed of an expandable member and a plurality of support members, and when folding, the expandable member stretches and bending portion 5153 is folded with a radius of curvature of 2 mm or more, preferably 5 mm or more.

[0372] Note that the display region 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 region 5152.

[0373] This embodiment mode can be combined with other embodiment modes as appropriate.

[0374] (Embodiment 7) In this embodiment, an example in which a light-emitting element of one embodiment of the present invention is applied to various lighting devices will be described with reference to Fig. 10 and Fig. 11. By using a light-emitting element of one embodiment of the present invention, a lighting device with high emission efficiency and high reliability can be manufactured.

[0375] By manufacturing the light-emitting element of one embodiment of the present invention over a flexible substrate, electronic devices and lighting devices each having a light-emitting region with a curved surface can be realized.

[0376] Furthermore, a light-emitting device to which a light-emitting element of one embodiment of the present invention is applied can also be used for lighting in an automobile; for example, lighting can be provided on a windshield, a ceiling, or the like.

[0377] 10A shows a perspective view of one side of a multifunction terminal 3500, and FIG. 10B shows a perspective view of the other side of the multifunction terminal 3500. The multifunction terminal 3500 includes a display unit 3504, a camera 3506, a light 3508, and the like incorporated in a housing 3502. The light-emitting device of one embodiment of the present invention can be used for the light 3508.

[0378] The lighting 3508 functions as a surface light source by using the light-emitting device of one embodiment of the present invention. Therefore, unlike a point light source typified by an LED, light emission with low directivity can be obtained. For example, when the lighting 3508 is used in combination with the camera 3506, the lighting 3508 can be turned on or blinked, and an image can be captured by the camera 3506. Since the lighting 3508 functions as a surface light source, a photograph similar to that taken under natural light can be captured.

[0379] The multifunction terminal 3500 shown in FIGS. 10(A) and (B) can have various functions, similar to the electronic devices shown in FIGS. 7(A) to 7(C).

[0380] Also, the housing 3502 may have a speaker, a sensor (including a function of measuring force, displacement, position, speed, acceleration, angular velocity, number of rotations, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared), a microphone, etc. Also, by providing a detection device having a sensor for detecting gradient such as a gyro or acceleration sensor inside the multifunction terminal 3500, the orientation of the multifunction terminal 3500 (portrait or landscape) can be determined and the screen display of the display unit 3504 can be automatically switched.

[0381] The display portion 3504 can also function as an image sensor. For example, identity authentication can be performed by touching the display portion 3504 with a palm or a finger to capture an image of a palm print, a fingerprint, or the like. In addition, finger veins, palm veins, or the like can be captured by using a backlight that emits near-infrared light or a sensing light source that emits near-infrared light for the display portion 3504. Note that the light-emitting device of one embodiment of the present invention may be applied to the display portion 3504.

[0382] 10C is a perspective view of a security light 3600. The light 3600 has a light 3608 on the outside of a housing 3602, and a speaker 3610 and the like are incorporated in the housing 3602. A light-emitting element of one embodiment of the present invention can be used for the light 3608.

[0383] The light 3600 can emit light, for example, by gripping, grasping, or holding the illumination 3608. The housing 3602 may also be provided with an electronic circuit capable of controlling the method of emitting light by the light 3600. The electronic circuit may be, for example, a circuit capable of emitting light once or intermittently multiple times, or a circuit capable of adjusting the amount of light emitted by controlling the current value of the light emission. A circuit may also be incorporated that outputs a loud alarm sound from the speaker 3610 simultaneously with the illumination of the illumination 3608.

[0384] Since the light 3600 can emit light in all directions, it can be used to scare off a thug with light or light and sound. The light 3600 may also be equipped with a camera such as a digital still camera or a function having a photographing function.

[0385] FIG. 11 shows an example in which a light-emitting element is used as an indoor lighting device 8501. Since the light-emitting element can be made large, a large-area lighting device can also be formed. In addition, by using a housing having a curved surface, a lighting device 8502 in which the light-emitting region has a curved surface can also be formed. The light-emitting element shown in this embodiment mode is a thin film, and the housing has a high degree of freedom in design. Therefore, lighting devices with various designs can be formed. Furthermore, a large-sized lighting device 8503 may be provided on a wall surface in a room. A touch sensor may be provided in the lighting devices 8501, 8502, and 8503 to turn the power on or off.

[0386] Furthermore, by using a light-emitting element on the front surface side of a table, the lighting device 8504 can function as a table. Note that by using a light-emitting element in part of other furniture, the lighting device can function as furniture.

[0387] In the above manner, a lighting device and an electronic device can be obtained by applying the light-emitting device of one embodiment of the present invention. Note that the applicable lighting device and electronic device are not limited to those described in this embodiment, and can be applied to electronic devices in any field.

[0388] The structure described in this embodiment mode can be used in appropriate combination with structures described in other embodiment modes. EXAMPLES

[0389] In this example, tris{2-[1-(2,6-diisobutylphenyl)-1H-naphtho[1,2-d]imidazol-2-yl-κN, which is one embodiment of the organometallic complex of the present invention shown in the structural formula (100) in Embodiment 1, is used. 3 This article describes the synthesis method of phenyl-κC}iridium(III) (abbreviation: [Ir(pni-diBup)3]).

[0390] <Step 1: Synthesis of 2,6-diisobutylaniline> 100g (617mmol) of 2,6-dichloroaniline, 230g (2256mmol) of isobutylboronic acid, 479g (2256mmol) of tripotassium phosphate, 10g (24.7mmol) of 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl (S-phos), and 3000mL of toluene were placed in a 5000mL three-neck flask, the atmosphere in the flask was replaced with nitrogen, and the mixture was degassed by stirring while reducing the pressure in the flask. After degassing, 11g (11.5mmol) of tris(dibenzylideneacetone)dipalladium(0) was added, and the mixture was stirred at 120°C for 12 hours under a nitrogen stream. After a predetermined time had passed, the resulting reaction solution was suction filtered. The resulting filtrate was purified by extraction with toluene. Then, the product was purified by silica column chromatography. The developing solvent used was hexane:toluene = 15:1. The obtained fraction was concentrated to obtain 79 g of the target black oily product in a yield of 62%. The synthesis scheme of step 1 is shown in the following formula (A-1).

[0391] [ka]

[0392] <Step 2: Synthesis of 2-nitronaphthalene-1-trifluoromethanesulfonate> 35g (182mmol) of 2-nitro-1-naphthol, 500mL of dehydrated dichloromethane, and 51mL (365mmol) of triethylamine were placed in a 1000mL three-neck flask, and the flask was replaced with nitrogen and cooled to 0℃. Here, 40mL (243mmol) of trifluoromethanesulfonic anhydride (abbreviation: Tf2O) was dropped, and the mixture was stirred at 0℃ for 1 hour and at room temperature for 20 hours. After a predetermined time, 300mL of water and 30mL of 1M hydrochloric acid were added to the obtained mixture. Then, this mixture was purified by extraction with dichloromethane. Then, it was purified by silica column chromatography. Hexane:dichloromethane=5:1 was used as the developing solvent. The obtained fraction was concentrated to obtain 47g of the target yellow oily product in 80% yield. The synthesis scheme of step 2 is shown in the following formula (A-2).

[0393] [ka]

[0394] <Step 3: Synthesis of N-(2,6-diisobutylphenyl)-2-nitro-1-naphthalenamine> 30g (146mmol) of 2,6-diisobutylaniline synthesized in step 1, 47g (146mmol) of 2-nitronaphthalene-1-trifluoromethanesulfonate synthesized in step 2, 81g (248mmol) of cesium carbonate, and 750mL of toluene were placed in a 2000mL three-neck flask, the flask was replaced with nitrogen, and the flask was stirred while reducing the pressure inside, and the mixture was degassed. After degassing, 4.8g (11.7mmol) of S-phos and 2.7g (2.9mmol) of tris(dibenzylideneacetone)dipalladium(0) were added, and the mixture was stirred at 130°C for 28 hours under a nitrogen stream. After a predetermined time had passed, the resulting reaction mixture was purified by extraction using toluene. It was then purified by silica column chromatography. Hexane:ethyl acetate = 15:1 was used as the developing solvent. The obtained fraction was concentrated to obtain 13g of a yellow oily product in a yield of 23%. The synthetic scheme of step 3 is shown in formula (A-3) below.

[0395] [ka]

[0396] <Step 4: Synthesis of N-(2,6-diisobutylphenyl)-1,2-naphthalenediamine> 13 g (34 mmol) of N-(2,6-diisobutylphenyl)-2-nitro-1-naphthaleneamine synthesized in step 3, 6.1 mL (0.34 mol) of water, and 400 mL of ethanol were placed in a 1000 mL three-neck flask and stirred. 32 g (0.17 mol) of tin(II) chloride was added to this mixture and stirred at 80°C for 5 hours under a nitrogen stream. After a predetermined time had passed, the resulting reaction mixture was poured into 500 mL of 2 M aqueous sodium hydroxide solution and stirred at room temperature for 2 hours. The precipitate was filtered by suction and washed with chloroform to obtain a filtrate. The obtained filtrate was purified by extraction using chloroform. It was then purified by silica column chromatography. Hexane: ethyl acetate = 15:1 was used as the developing solvent. The obtained fraction was concentrated to obtain 9.5 g of the target black oily product in a yield of 81%. The synthesis scheme of step 4 is shown in the following formula (A-4).

[0397] [ka]

[0398] <Step 5: Synthesis of 1-(2,6-diisobutylphenyl)-2-phenyl-1H-naphtho[1,2-d]imidazole (abbreviation: Hpni-diBup)> 9.5g (27mmol) of N-(2,6-diisobutylphenyl)-1,2-naphthalenediamine synthesized in step 4, 100mL of acetonitrile, and 2.9g (27mmol) of benzaldehyde were placed in a 300mL eggplant flask and stirred at 100°C for 6 hours. 0.044g (0.274mmol) of iron chloride (III) was added to this mixture and stirred at 100°C for 16 hours. After a predetermined time, the reaction mixture was extracted with ethyl acetate, and 100mL of toluene and 10g of manganese oxide (IV) were added to the oily product in a 300mL eggplant flask and stirred at 130°C for 7 hours. After a predetermined time, the reaction mixture was suction filtered through Celite (Wako Pure Chemical Industries, Ltd., catalog number: 537-02305) / Florisil (Wako Pure Chemical Industries, Ltd., catalog number: 066-05265) / aluminum oxide. The filtrate was concentrated to obtain an oily product. The oily product was purified by silica column chromatography. Toluene was used as the developing solvent. The fraction was concentrated to obtain 7.9 g of the target white solid in a yield of 66%. The synthesis scheme of step 5 is shown in the following formula (A-5).

[0399] [ka]

[0400] <Step 6; Di-μ-chloro-tetrakis{2-[1-(2,6-diisobutylphenyl)-1H-naphtho[1,2-d]imidazol-2-yl-κN 3 Synthesis of phenyl-κC}diiridium(III) (abbreviation: [Ir(pni-diBup)2Cl]2) 3.3g (7.7mmol) of 1-(2,6-diisobutylphenyl)-2-phenyl-1H-naphtho[1,2-d]imidazole (abbreviation: Hpni-diBup) synthesized in step 5, 1.6g (3.7mmol) of iridium chloride monohydrate, 30mL of 2-ethoxyethanol, and 10mL of water were placed in a 100mL round-bottom flask, and the atmosphere in the flask was replaced with argon. The reaction vessel was irradiated with microwaves (2.45GHz, 100W) for 2 hours to cause a reaction. After the reaction, the reaction solution was suction filtered to obtain 2.8g of the target yellow solid in a yield of 69%. The synthesis scheme of step 6 is shown in the following formula (A-6).

[0401] [ka]

[0402] < Step 7; Tris{2-[1-(2,6-diisobutylphenyl)-1H-naphtho[1,2-d]imidazol-2-yl-κN 3 Synthesis of phenyl-κC}iridium(III) (abbreviation: [Ir(pni-diBup)3]) Di-μ-chloro-tetrakis{2-[1-(2,6-diisobutylphenyl)-1H-naphtho[1,2-d]imidazol-2-yl-κN} synthesized by the method of step 6 32.0 g (0.92 mmol) of ]phenyl-κC}diiridium(III) (abbreviation: [Ir(pni-diBup)2Cl]2) and 150 mL of dichloromethane were placed in a 500 mL three-neck flask and stirred under a nitrogen stream. A mixed solution of 0.72 g (2.8 mmol) of silver trifluoromethanesulfonate and 150 mL of methanol was added dropwise to this mixed solution and stirred in the dark for 3 days. After reacting for a predetermined time, the reaction mixture was passed through Celite and filtered. The filtrate was concentrated to obtain 2.7 g of a yellow solid. 2.7 g of the obtained solid, 50 mL of ethanol, and 1.6 g (3.7 mmol) of 1-(2,6-diisobutylphenyl)-2-phenyl-1H-naphtho[1,2-d]imidazole (abbreviation: Hpni-diBup) synthesized by the method in step 5 were placed in a 500 mL eggplant flask and heated to reflux for 20 hours under a nitrogen stream. After reacting for a predetermined time, the reaction mixture was suction filtered to obtain a solid. The obtained solid was dissolved in dichloromethane and suction filtered through Celite / neutral silica / Celite. The obtained filtrate was concentrated to obtain a solid. The obtained solid was purified by silica column chromatography. The developing solvent used was dichloromethane:hexane = 1:3. The obtained fraction was concentrated to obtain a solid. The obtained solid was recrystallized with ethyl acetate / hexane to obtain 1.1 g of a solid in a yield of 40%. The synthesis scheme is shown in the following formula (A-7).

[0403] [ka]

[0404] The obtained solid (1.1 g) was purified by train sublimation. The sublimation purification was performed by heating the obtained solid at 340°C for 41 hours under the conditions of a pressure of 2.6 Pa and an argon flow rate of 10.5 mL / min. After the sublimation purification, 0.93 g of a yellow solid was obtained with a recovery rate of 88%.

[0405] The proton NMR of the yellow solid obtained above ( 1 H-NMR) measurements were performed. The values ​​obtained are shown below. 1The H-NMR chart is shown in Figure 12. From Figure 12, it was found that [Ir(pni-diBup)3], which is an organometallic complex of one embodiment of the present invention, was obtained.

[0406] 1 H-NMR.δ(CD2Cl2):0.15(d,9H),0.39-0.42(m,18H),0.59(d,9H),1.27-1.35(m,3H),1.78-1.86(m,3H),1.93-2.02(m,6H),2.33(d,6H),6.35- 6.40(m,6H),6.56-6.61(m,6H),7.04-7.07(m,6H),7.16(t,3H),7.25(d ,3H),7.30(t,3H),7.40(d,3H),7.48(d,3H),7.63(t,3H),7.73(d,3H).

[0407] Next, the ultraviolet-visible absorption spectrum (hereinafter simply referred to as "absorption spectrum") and emission spectrum of the [Ir(pni-diBup)3] solution were measured. The absorption spectrum was measured using an ultraviolet-visible spectrophotometer (V550 type, manufactured by JASCO Corporation), and a deoxygenated dichloromethane solution (0.0089 mmol / L) of [Ir(pni-diBup)3] was placed in a quartz cell and measured at room temperature. The emission spectrum and emission quantum yield were measured using an absolute PL quantum yield measurement device (C11347-01, manufactured by Hamamatsu Photonics Co., Ltd.), and the deoxygenated dichloromethane solution (0.0089 mmol / L) was placed in a quartz cell in a nitrogen atmosphere in a glove box (LABstarM13 (1250 / 780), manufactured by Bright Co., Ltd.) and measured at room temperature. The measurement results of the obtained absorption spectrum and emission spectrum are shown in FIG. 13. The horizontal axis represents the wavelength, and the vertical axis represents the absorption intensity and emission intensity. The absorption spectrum shown in FIG. 13 is the result obtained by subtracting the absorption spectrum measured by putting only dichloromethane in a quartz cell from the absorption spectrum measured by putting a deoxygenated dichloromethane solution in a quartz cell.

[0408] As shown in FIG. 13, the iridium complex [Ir(pni-diBup)3] has emission peaks at 500 and 536 nm, and green emission was observed from the deoxygenated dichloromethane solution.

[0409] In addition, the emission quantum yield at an excitation wavelength of 450 nm in a deoxygenated dichloromethane solution was measured and found to be extremely high at 98%. EXAMPLES

[0410] In this example, bis{2-[1-(2,6-diisobutylphenyl)-1H-naphtho[1,2-d]imidazol-2-yl-κN, which is an organometallic complex according to one embodiment of the present invention shown in structural formula (101) in Embodiment 1, is used. 3 ]phenyl-κC}[2-(4-methyl-5-phenyl-2-pyridyl-κN 2 This article describes a method for synthesizing [Ir(pni-diBup)2(mdppy)], a phenyl-κC iridium(III) compound.

[0411] <Step 1; Bis{2-[1-(2,6-diisobutylphenyl)-1H-naphtho[1,2-d]imidazol-2-yl-κN 3 ]phenyl-κC}[2-(4-methyl-5-phenyl-2-pyridyl-κN 2 Synthesis of [phenyl-κC]iridium(III) (abbreviation: [Ir(pni-diBup)2(mdppy)]) Di-μ-chloro-tetrakis[2-(4-methyl-5-phenyl-2-pyridinyl-κN)phenyl-κC]diiridium(III) (abbreviation: [Ir(mdppy)2Cl]2) 1.3g (0.9mmol) and dichloromethane 180mL were placed in a 500mL three-neck flask and stirred under nitrogen flow. A mixed solution of silver trifluoromethanesulfonate 0.7g (2.7mmol) and methanol 35mL was added dropwise to this mixed solution and stirred in the dark for 18 hours. After reacting for a predetermined time, the reaction mixture was passed through Celite and filtered. The obtained filtrate was concentrated to obtain 1.9g of a yellow solid. The obtained yellow solid 1.9g, methanol 30mL, ethanol 30mL, and Hpni-diBup 1.6g (3.6mmol) were placed in a 300mL eggplant flask and heated under reflux for 23 hours under nitrogen flow. After reacting for a predetermined time, the reaction mixture was suction filtered, insoluble matter was removed, and the filtrate was concentrated to obtain a solid. 60 mL of 1-butanol was added to the obtained solid, and the mixture was heated under reflux for 22 hours under a nitrogen stream. After reacting for a predetermined time, the reaction mixture was suction filtered to obtain a solid. The obtained solid was purified by silica column chromatography. A mixed solvent of hexane:dichloromethane = 3:1 was used as the developing solvent. The obtained fraction was concentrated to obtain a solid. The obtained solid was recrystallized with ethyl acetate / hexane to obtain 0.20 g of the target yellow solid in a yield of 9%. The synthesis scheme is shown in the following formula (B-1).

[0412] [ka]

[0413] The obtained solid (0.19 g) was purified by train sublimation. The sublimation purification was performed by heating the obtained solid at 320°C for 18 hours under the conditions of a pressure of 2.5 Pa and an argon flow rate of 10.3 mL / min. After the sublimation purification, 0.14 g of a yellow solid was obtained with a recovery rate of 72%.

[0414] The yellow solid obtained above 1 H-NMR measurement was performed. The values ​​obtained are shown below. 1The H-NMR chart is shown in Figure 14. From Figure 14, it was found that [Ir(pni-diBup)2(mdppy)], which is an organometallic complex of one embodiment of the present invention, was obtained.

[0415] 1 H-NMR.δ(CD2Cl2):0.09-0.15(m,9H),0.29-0.34(m,9H),0.40(t,1H),0.45(d,3H),0.51(d,3H),1.18-1.24( m,1H),1.34-1.49(m,1H),1.70-1.78(m,1H),1.88-2.09(m,6H),2.17-2.25(m,2H),2.51(s,3H),6.30-6.40(m ,3H),6.48(t,1H),6.61-6.52(m,3H),6.64-6.69(m,2H),6.74-6.79(m,2H),6.83(t,1H),6.93-7.01(m,3H), 7.08(t,1H),7.13-7.25(m,8H),7.34-7.51(m,6H),7.57-7.73(m,4H),7.87(d,1H),7.94(s,1H),8.31(s,1H).

[0416] Next, the absorption spectrum, emission spectrum, and emission quantum yield of a deoxygenated dichloromethane solution (0.0073 mmol / L) of [Ir(pni-diBup)2(mdppy)] were measured. The measurements were performed in the same manner as in Example 1. The measurement results of the absorption spectrum and emission spectrum are shown in FIG.

[0417] As shown in FIG. 15, the iridium complex [Ir(pni-diBup)2(mdppy)] has an emission peak at 530 nm, and green emission was observed from the deoxygenated dichloromethane solution.

[0418] In addition, the luminescence quantum yield at an excitation wavelength of 450 nm in a deoxygenated dichloromethane solution (0.0073 mmol / L) was measured and found to be extremely high at 98%. EXAMPLES

[0419] In this example, tris{2-[1-(4-cyano-2-isobutylphenyl)-1H-naphtho[1,2-d]imidazol-2-yl-κN, which is an organometallic complex of one embodiment of the present invention shown in Embodiment 1 as structural formula (102), 3 This article describes a method for synthesizing phenyl-κC}iridium(III) (abbreviation: [Ir(pni-iBuCNp)3]).

[0420] <Step 1: Synthesis of 4-amino-3-isobutylbenzonitrile> 75g (492mmol) of 4-amino-3-chlorobenzonitrile, 90g (886mmol) of isobutylboronic acid, 188g (886mmol) of tripotassium phosphate, 4.0g (9.8mmol) of 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl (S-phos), and 2400mL of toluene were placed in a 5000mL three-neck flask, the flask was replaced with nitrogen, and the flask was stirred while reducing the pressure inside, and the mixture was degassed. After degassing, 4.5g (4.9mmol) of tris(dibenzylideneacetone)dipalladium(0) was added, and the mixture was stirred at 120°C for 20 hours under a nitrogen stream. After a predetermined time had passed, the obtained reaction solution was suction filtered. The obtained filtrate was purified by extraction using toluene. Then, it was purified by silica column chromatography. Toluene was used as the developing solvent. The obtained fraction was concentrated to obtain 59g of the desired brown oily product in a yield of 69%. The synthetic scheme of step 1 is shown in formula (C-1) below.

[0421] [ka]

[0422] <Step 2: Synthesis of 3-isobutyl-4-[N-(2-nitronaphthyl)amino]benzonitrile> 30g (170mmol) of 4-amino-3-isobutylbenzonitrile synthesized in step 1, 45g (141mmol) of 2-nitronaphthalene-1-trifluoromethanesulfonate, 78g (240mmol) of cesium carbonate, and 750mL of toluene were placed in a 2000mL three-neck flask, the flask was replaced with nitrogen, and the mixture was degassed by stirring while reducing the pressure inside the flask. After degassing, 4.6g (11mmol) of 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl (S-phos) and 2.6g (2.8mmol) of tris(dibenzylideneacetone)dipalladium(0) were added, and the mixture was stirred at 130°C for 24 hours under a nitrogen stream. After a predetermined time had passed, the resulting reaction mixture was purified by extraction with toluene. It was then purified by silica column chromatography. The developing solvent used was hexane:ethyl acetate = 10:1. The obtained fraction was concentrated to obtain 40 g of the target yellow oily product in a yield of 82%. The synthetic scheme of step 2 is shown in the following formula (C-2).

[0423] [ka]

[0424] <Step 3: Synthesis of 3-isobutyl-4-[N-(1,2-naphthalenediamine)]benzonitrile> 40 g (115 mmol) of 3-isobutyl-4-[N-(2-nitronaphthyl)amino]benzonitrile synthesized in step 2, 21 mL (1.2 mol) of water, and 1350 mL of ethanol were placed in a 3000 mL three-neck flask and stirred. 109 g (0.58 mol) of tin(II) chloride was added to this mixture and stirred at 80°C for 6 hours under a nitrogen stream. After a predetermined time had passed, the resulting reaction mixture was poured into 500 mL of 2 M aqueous sodium hydroxide solution and stirred at room temperature for 2 hours. The precipitate was filtered by suction and washed with chloroform to obtain a filtrate. The obtained filtrate was purified by extraction using chloroform. Hexane was then added to the obtained solid, and suction filtration was performed to obtain 32 g of a white solid with a yield of 88%. The synthesis scheme of step 3 is shown in the following formula (C-3).

[0425] [ka]

[0426] <Step 4: Synthesis of 1-(4-cyano-2-isobutylphenyl)-2-phenyl-1H-naphtho[1,2-d]imidazole (abbreviation: Hpni-iBuCNp)> 32g (101mmol) of 3-isobutyl-4-[N-(1,2-naphthalenediamine)]benzonitrile synthesized in step 3, 400mL of acetonitrile, and 11g (101mmol) of benzaldehyde were placed in a 1000mL three-neck flask and stirred at 100℃ for 6 hours. 0.16g (1.0mmol) of iron(III) chloride was added to this mixture and stirred at 100℃ for 16 hours. After a predetermined time, the reaction mixture was extracted with ethyl acetate. The solid obtained was then purified by silica column chromatography. As the developing solvent, toluene was used first, and then a mixed solvent of toluene:ethyl acetate = 18:1 was used. The obtained fraction was concentrated to obtain a solid. Ethyl acetate was added to the obtained solid, and the mixture was filtered by suction to obtain 14g of the target white solid with a yield of 34%. The synthesis scheme of step 4 is shown in the following formula (C-4).

[0427] [ka]

[0428] < Step 5; Tris{2-[1-(4-cyano-2-isobutylphenyl)-1H-naphtho[1,2-d]imidazol-2-yl-κN 3 Synthesis of phenyl-κC}iridium(III) (abbreviation: [Ir(pni-iBuCNp)3]) 3.8 g (9.5 mmol) of 1-(4-cyano-2-isobutylphenyl)-2-phenyl-1H-naphtho[1,2-d]imidazole synthesized by the method of step 4 and 0.93 g (1.9 mmol) of tris(acetylacetonato)iridium(III) were placed in a reaction vessel equipped with a three-way cock and heated at 250°C for 40 hours. Dichloromethane was added to the resulting reaction mixture to remove insoluble matter. The resulting filtrate was concentrated to obtain a solid. The resulting solid was purified by silica column chromatography. Dichloromethane was used as the developing solvent. The obtained fraction was concentrated to obtain a solid. The resulting solid was recrystallized with ethyl acetate / hexane to obtain 0.3 g of a yellow solid in a yield of 10%. This synthesis scheme is shown in the following formula (C-5).

[0429] [ka]

[0430] The mass (MS) of the yellow solid obtained above was measured. The ESI-MS measurement results of the obtained compound are shown below. ESI-MS [M+H + ]=1394.51 (Exact Mass=1393.51). From this, it was found that [Ir(pni-iBuCNp)3]), which is one embodiment of the organometallic complex of the present invention represented by the above structural formula (102), was obtained.

[0431] Next, the absorption spectrum and emission spectrum of the dichloromethane deoxygenated solution (0.013 mmol / L) of [Ir(pni-iBuCNp)3] obtained above were measured. The measurement was performed in the same manner as in Example 1. The absorption spectrum and emission spectrum are shown in FIG.

[0432] As shown in FIG. 16, the iridium complex [Ir(pni-iBuCNp)3] has emission peaks at 509 and 544 nm, and green emission was observed from the deoxygenated dichloromethane solution. EXAMPLES

[0433] In this example, a compound represented by structural formula (103) in Embodiment 1, which is an organometallic complex of one embodiment of the present invention, is used. 3 This article describes a method for synthesizing phenyl-κC}iridium(III) (abbreviation: [Ir(pni-diBuCNp)3]).

[0434] <Step 1: Synthesis of 4-amino-3,5-diisobutylbenzonitrile> 58g (310mmol) of 4-amino-3,5-diisobutylbenzonitrile, 117g (1145mmol) of isobutylboronic acid, 243g (1145mmol) of tripotassium phosphate, 6.4g (15.5mmol) of 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl (S-phos), and 1500ml of toluene were placed in a 3000mL three-necked reaction vessel, the atmosphere in the flask was replaced with nitrogen, and the mixture was degassed by stirring while reducing the pressure in the flask. After degassing, 5.7g (6.2mmol) of tris(dibenzylideneacetone)dipalladium(0) was added, and the mixture was stirred at 130°C for 12 hours under a nitrogen stream. Toluene was added to the obtained reaction solution, and the mixture was suction-filtered through Celite. The obtained filtrate was purified by extraction with toluene. Then, the mixture was purified by silica column chromatography. Toluene was used as the developing solvent. The obtained fraction was concentrated to obtain 69 g of the target yellow oily product in a yield of 96%. The synthesis scheme of step 1 is shown in the following formula (D-1).

[0435] [ka]

[0436] <Step 2: Synthesis of 3,5-diisobutyl-4-[N-(2-nitronaphthyl)amino]benzonitrile> 28g (121mmol) of 4-amino-3,5-diisobutylbenzonitrile synthesized in step 1, 39g (121mmol) of 2-nitronaphthalene-1-trifluoromethanesulfonate, 67g (205mmol) of cesium carbonate, and 750mL of toluene were placed in a 2000mL three-neck flask, the flask was replaced with nitrogen, and the flask was stirred while reducing the pressure inside, and the mixture was degassed. After degassing, 4.0g (9.7mmol) of 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl (S-phos) and 2.2g (2.4mmol) of tris(dibenzylideneacetone)dipalladium(0) were added, and the mixture was stirred at 130°C for 40 hours under a nitrogen stream. After a certain time had passed, the resulting reaction mixture was purified by extraction with toluene. Then, it was purified by silica column chromatography. The developing solvent used was hexane:ethyl acetate = 10:1. The obtained fraction was concentrated to obtain 4.5 g of the target orange solid in a yield of 9%. The synthesis scheme of Step 2 is shown in the following formula (D-2).

[0437] [ka]

[0438] <Step 3: Synthesis of 3,5-diisobutyl-4-[N-(1,2-naphthalenediamine)]benzonitrile> 4.5g (11mmol) of 3,5-diisobutyl-4-[N-(2-nitronaphthyl)amino]benzonitrile synthesized in step 2, 2mL (110mmol) of water, and 130mL of ethanol were placed in a 500mL three-neck flask and stirred. 10.4g (55mmol) of tin(II) chloride was added to this mixture and stirred at 80°C for 7.5 hours under a nitrogen stream. After a predetermined time had passed, the reaction mixture obtained was poured into 100mL of 2M aqueous sodium hydroxide solution and stirred at room temperature for 2 hours. The precipitate was filtered by suction and washed with chloroform to obtain a filtrate. The filtrate obtained was extracted with chloroform. The extracted solution obtained was then concentrated to obtain 4.1g of the target black oily product in a yield of 99%. The synthesis scheme of step 3 is shown in the following formula (D-3).

[0439] [ka]

[0440] <Step 4: Synthesis of 1-(4-cyano-2,6-diisobutylphenyl)-2-phenyl-1H-naphtho[1,2-d]imidazole (abbreviation: Hpni-diBuCNp)> 4.2g (11mmol) of 3,5-diisobutyl-4-[N-(1,2-naphthalenediamine)]benzonitrile synthesized in step 3, 50mL of acetonitrile, and 1.2g (11mmol) of benzaldehyde were placed in a 500mL three-neck flask and stirred at 100℃ for 8 hours. 18mg (0.11mmol) of iron(III) chloride was added to this mixture and stirred at 100℃ for 29 hours. After a predetermined time, the reaction mixture was purified by extraction with ethyl acetate. The solid obtained was then purified by silica column chromatography. Toluene was used as the developing solvent first, and then a mixed solvent of toluene:ethyl acetate = 20:1 was used. The obtained fraction was concentrated to obtain 2.9g of the target black oily product in a yield of 58%. The synthesis scheme of step 4 is shown in the following formula (D-4).

[0441] [ka]

[0442] < Step 5; Tris{2-[1-(4-cyano-2,6-diisobutylphenyl)-1H-naphtho[1,2-d]imidazol-2-yl-κN 3 Synthesis of phenyl-κC}iridium(III) (abbreviation: [Ir(pni-diBuCNp)3]) 2.9g (6.3mmol) of 1-(4-cyano-2,6-diisobutylphenyl)-2-phenyl-1H-naphtho[1,2-d]imidazole synthesized by the method of steps 1 to 4 and 0.62g (1.3mmol) of tris(acetylacetonato)iridium(III) were placed in a reaction vessel equipped with a three-way cock and heated at 250°C for 56 hours. Toluene was added to the obtained reaction mixture and filtered to remove insoluble matter. The obtained filtrate was concentrated to obtain a solid. The obtained solid was purified by silica column chromatography. Toluene was used as the developing solvent. The obtained fraction was concentrated to obtain a solid. The obtained solid was recrystallized with ethyl acetate / hexane to obtain 0.33g of a yellow solid in a yield of 16%. The synthesis scheme is shown in the following formula D-5).

[0443] [ka]

[0444] The obtained solid (0.32 g) was purified by train sublimation. The purification was performed by heating at 345°C for 17 hours under the conditions of a pressure of 2.5 Pa and an argon flow rate of 10.4 mL / min. After purification by sublimation, 0.10 g was obtained, with a recovery rate of 31%.

[0445] The yellow solid obtained above 1 H-NMR was measured. The values ​​obtained are shown below. 1 The H-NMR chart is shown in Figure 17. From Figure 17, it was found that [Ir(pni-diBuCNp)3], which is an organometallic complex of one embodiment of the present invention, was obtained.

[0446] 1H-NMR.δ(ppm from CH2Cl2),(CD2Cl2):-0.38(d,3H),-0.13--0.06(m,9H),0.35(d,3H),0.41-0.45(m,6H),0.54-0.57(m,6 H),0.62-0.65(m,6H),0.70(d,3H),1.14-1.23(m,1H),1.27-1.35(m,1H),1.40-1.49(m,1H),1.50-1.57 (m,1H),1.60-1.66(m,2H),1.71-1.90(m,4H),2.06-2.15(m,2H),2.22-2.31(m,4H),2.33-2.42(t,2H), 6.32-6.39(m,3H),6.53-6.85(m,12H),6.96(t,2H),7.06(d,1H),7.10-7.37(m,9H),7.66-7.83(m,9H).

[0447] Next, the absorption spectrum, emission spectrum, and emission quantum yield of a deoxygenated dichloromethane solution of [Ir(pni-diBuCNp)3] (0.0084 mmol / L) were measured. The measurement results of the absorption spectrum and emission spectrum are shown in FIG.

[0448] As shown in FIG. 18, the iridium complex [Ir(pni-diBuCNp)3] has emission peaks at 510 and 547 nm, and green emission was observed from the deoxygenated dichloromethane solution.

[0449] In addition, the luminescence quantum yield at an excitation wavelength of 450 nm in a deoxygenated dichloromethane solution (0.0084 mmol / L) was measured and found to be extremely high at 91%. EXAMPLES

[0450] The luminescence quantum yields of the compounds synthesized as described above, [Ir(pni-diBup)3], [Ir(pni-diBup)2(mdppy)], and [Ir(pni-diBuCNp)3], were measured. In addition, the comparative compound (OC-6-22)-tris{2-[1-(2,6-diisobutylphenyl)-1H-benzimidazol-2-yl-κN 3The luminescence quantum yield of ]phenyl-κC}iridium(III) (abbreviation: fac-[Ir(pbi-diBup)3] was also measured. The measurement was performed in the same manner as in Example 1. The results are shown in Table 1.

[0451] [Table 1]

[0452] The difference in structure between [Ir(pni-diBup)3] and fac-[Ir(pbi-diBup)3], which are organometallic complexes according to one embodiment of the present invention, is whether or not they have a benzene ring fused to the g-position of the benzimidazole skeleton. As shown in Table 1, the organometallic complex according to one embodiment of the present invention exhibits a better emission quantum yield. In addition, it was found that an organometallic complex having a 1H-naphtho[1,2-d]imidazole skeleton as a ligand exhibits an extremely high emission quantum yield of more than 90%. EXAMPLES

[0453] In this example, a manufacturing example of a light-emitting element and a comparative light-emitting element including an organic compound according to one embodiment of the present invention and characteristics of the light-emitting element will be described. FIG. 1A shows the stacked structure of the light-emitting element manufactured in this example. Table 2 shows details of the element structure. The organic compounds used in this example are listed below. Note that other organic compounds may be referred to in other embodiments or examples.

[0454] [ka]

[0455] [Table 2]

[0456] <Preparation of comparative light-emitting element 1> An ITSO film was formed as an electrode 101 on a glass substrate by sputtering to a thickness of 70 nm. The electrode area of ​​the electrode 101 was 4 mm2 (2mm x 2mm). Next, as a pretreatment for forming a light-emitting element on the substrate, the substrate surface was washed with water, dried at 200°C for 1 hour, and then subjected to UV ozone treatment for 370 seconds. -4 The substrate was placed in a vacuum deposition apparatus maintained at a vacuum of about Pa, and baked at 170° C. for 30 minutes. Thereafter, the substrate was allowed to cool for about 30 minutes.

[0457] Next, as a hole injection layer 111, DBT3P-II and molybdenum oxide (VI) (MoO3) were co-deposited on the electrode 101 in a weight ratio (DBT3P-II:MoO3) of 1:0.5 to a thickness of 40 nm.

[0458] Next, PCCP was deposited on the hole injection layer 111 as a hole transport layer 112 to a thickness of 20 nm.

[0459] Next, 4,6mCzP2Pm, PCCP, and [Ir(ppy)3] were co-deposited on the hole transport layer 112 in a weight ratio (4,6mCzP2Pm:PCCP:[Ir(ppy)3]) of 0.6:0.4:0.1 to a thickness of 40 nm to form the light emitting layer 140. In the light emitting layer 140, [Ir(ppy)3] is a guest material that exhibits phosphorescence.

[0460] Next, 4,6mCzP2Pm was deposited to a thickness of 20 nm as electron transport layer 118(1) on light-emitting layer 140. Next, NBPhen was deposited to a thickness of 10 nm as electron transport layer 118(2) on electron transport layer 118(1).

[0461] Next, LiF was deposited on the electron transport layer 118 as the electron injection layer 119 to a thickness of 1 nm.

[0462] Next, on the electron injection layer 119, aluminum (Al) was formed as the electrode 102 to a thickness of 200 nm.

[0463] Next, in a glove box with a nitrogen atmosphere, a substrate (opposite substrate) different from the substrate on which the light-emitting element is formed was fixed to the substrate on which the light-emitting element is formed in order to seal the comparative light-emitting element 1. Specifically, a desiccant was attached to the opposite substrate, and the opposite substrate on which the sealing material was applied around the area on which the light-emitting element was formed was attached to the glass substrate on which the light-emitting element was formed, and ultraviolet light having a wavelength of 365 nm was applied at 6 J / cm. 2 The light-emitting element was then irradiated with light and then heat-treated for 1 hour at 80° C. Through the above steps, a comparative light-emitting element 1 was obtained.

[0464] <Fabrication of Comparative Light-Emitting Element 2, Comparative Light-Emitting Element 3, and Light-Emitting Element 4> The manufacturing process of the comparative light-emitting element 2, the comparative light-emitting element 3, and the light-emitting element 4 differs from that of the comparative light-emitting element 1 described above only in the manufacturing process of the light-emitting layer 140, and the other manufacturing processes are the same as those of the comparative light-emitting element 1. Since the element structures of the comparative light-emitting element 2, the comparative light-emitting element 3, and the light-emitting element 4 are as shown in Table 2, detailed descriptions of the manufacturing processes will be omitted. Note that the light-emitting layer 140 of the comparative light-emitting element 2, the comparative light-emitting element 3, and the light-emitting element 4 was formed by vacuum deposition, as in the comparative light-emitting element 1.

[0465] The element structures of the comparative light-emitting element 1 to the comparative light-emitting element 3 and the light-emitting element 4 are different only in the guest material used in the light-emitting layer 140, and the other configurations are the same for all the light-emitting elements. Note that the light-emitting element 4 uses [Ir(pni-diBup)3] which is an organic compound of one embodiment of the present invention, and the comparative light-emitting element 3 uses fac-[Ir(pbi-diBup)3] which is a comparative substance. In addition, the comparative light-emitting element 1 and the comparative light-emitting element 2 use [Ir(ppy)3] and GD270 (manufactured by Jilin OLED Co., Ltd.), which are widely used as guest materials, respectively.

[0466] <Characteristics of light-emitting element> Next, the characteristics of the prepared comparative light-emitting elements 1 to 3 and light-emitting element 4 were measured. A color luminance meter (BM-5A, manufactured by Topcon Corporation) was used to measure the luminance and CIE chromaticity, and a multichannel spectrometer (PMA-11, manufactured by Hamamatsu Photonics KK) was used to measure the electroluminescence spectrum.

[0467] FIG 19 shows current efficiency vs. luminance characteristics of the comparative light-emitting element 1 to the comparative light-emitting element 3 and the light-emitting element 4. FIG 20 shows current density vs. voltage characteristics. FIG 21 shows external quantum efficiency vs. luminance characteristics. Note that the measurement of each light-emitting element was performed at room temperature (atmosphere maintained at 23° C.). In addition, the comparative light-emitting element 1 to the comparative light-emitting element 3 and the light-emitting element 4 had a current density of 2.5 mA / cm 2 FIG. 22 shows the emission spectrum when a current was passed at a current density of 1000 .mu.m.

[0468] Also, 1000cd / m 2 Table 3 shows the element characteristics of the comparative light-emitting elements 1 to 3 and the light-emitting element 4 in the vicinity.

[0469] [Table 3]

[0470] 22, the emission spectra of the comparative light-emitting element 1 to the comparative light-emitting element 3, and the light-emitting element 4 have spectral peaks at approximately 518 nm, 523 nm, 508 nm, and 500 nm, respectively, and the full widths at half maximum are approximately 74 nm, 73 nm, 63 nm, and 27 nm, respectively. This indicates that the comparative light-emitting element 1 to the comparative light-emitting element 3, and the light-emitting element 4 emit light originating from the guest material contained in each of the light-emitting elements.

[0471] As shown in FIG. 19 and Table 3, the comparative light-emitting element 1 to the comparative light-emitting element 3, and the light-emitting element 4 all exhibited high current efficiency. The light-emitting element 4 has an emission spectrum in a region (short wavelength region) with lower luminosity than the comparative light-emitting elements 1 to 3, but has current efficiency equivalent to those of the comparative light-emitting elements 1 to 3. As shown in FIG. 21 and Table 3, the light-emitting element 4 was found to have extremely high external quantum efficiency of more than 25%. The light-emitting element 4 also exhibited higher efficiency than the comparative light-emitting element 1 and the comparative light-emitting element 2, which used [Ir(ppy)3] or GD270, which are widely used as guest materials. The light-emitting element 4 also emitted light on the shorter wavelength side than the light-emitting element 3, but had external quantum efficiency equivalent to or higher than that of the light-emitting element 3.

[0472] As shown in FIG. 20 and Table 3, each of the comparative light-emitting elements 1 to 3 and the light-emitting element 4 was found to have favorable driving voltage characteristics. EXAMPLES

[0473] In this example, a manufacturing example of a light-emitting element containing an organometallic complex according to one embodiment of the present invention, different from that in Example 6, and characteristics of the light-emitting element will be described. FIG. 1A shows the stacked structure of the light-emitting element manufactured in this example. Table 4 shows details of the element structure. Organic compounds used in this example are listed below. Note that other organic compounds can be found in other embodiments or examples.

[0474] [ka]

[0475] [Table 4]

[0476] <Fabrication of Light-Emitting Element 5> The light-emitting element 5 was formed by vacuum evaporation in the same manner as the comparative light-emitting element 1 to comparative light-emitting element 3 and light-emitting element 4. The element structure of light-emitting element 5 is as shown in Table 4, and therefore detailed description of the manufacturing process will be omitted. Light-emitting element 5 is a light-emitting element that uses a heteroorganometallic complex (a metal complex having two or more types of ligands) of one embodiment of the present invention.

[0477] <Characteristics of light-emitting element> Next, the characteristics of the fabricated light-emitting element 5 were measured. The measurement conditions for the light-emitting element 5 were the same as those in the previous examples.

[0478] FIG 23 shows current efficiency vs. luminance characteristics of the light-emitting element 5. FIG 24 shows current density vs. voltage characteristics. FIG 25 shows external quantum efficiency vs. luminance characteristics. 2 FIG. 26 shows the emission spectrum when a current was passed at a current density of 1000 .mu.m.

[0479] Also, 1000cd / m 2 Table 5 shows the element characteristics of the light-emitting element 5 in the vicinity.

[0480] [Table 5]

[0481] Furthermore, as shown in FIG. 26, the emission spectrum of the light-emitting element 5 had a spectral peak at about 523 nm and a full width at half maximum of about 63 nm, indicating that the light-emitting element 5 emitted light originating from the guest material [Ir(pni-diBup)2(mdppy)].

[0482] 23, 25, and Table 5, the Light-emitting Device 5 exhibited high current efficiency and external quantum efficiency. In particular, the external quantum efficiency was extremely high, exceeding 25%.

[0483] As shown in FIG. 24 and Table 5, it was found that the light-emitting element 5 had good driving voltage characteristics. Showed the light.

[0484] <Reliability of light-emitting elements> Next, a constant current drive test of the light-emitting element 5 at 2 mA was carried out. The results are shown in FIG. 27. As shown in FIG. 27, the light-emitting element 5 has a LT 70 The time required for the brightness to decrease by 30% exceeded 100 hours, demonstrating the excellent reliability. EXAMPLES

[0485] In this example, a manufacturing example of a light-emitting element containing an organometallic complex according to one embodiment of the present invention, which is different from that in Examples 6 and 7, and characteristics of the light-emitting element will be described. The stacked structure of the light-emitting element manufactured in this example is shown in FIG. 1A. Details of the element structure are shown in Table 6.

[0486] [Table 6]

[0487] <Preparation of Comparative Light-Emitting Element 6 and Light-Emitting Element 7> Comparative light-emitting element 6 and light-emitting element 7 were fabricated by vacuum deposition in the same manner as for light-emitting element 5 described above. Since the element structures of comparative light-emitting element 6 and light-emitting element 7 are as shown in Table 6, detailed fabrication steps will be omitted. Light-emitting element 7 is a light-emitting element that uses [Ir(pni-diBuCNp)3], which is an organometallic complex of one embodiment of the present invention, as a guest material. Note that comparative light-emitting element 6 is a light-emitting element that uses GD270 as a guest material.

[0488] <Characteristics of light-emitting element> Next, the characteristics of the comparative light-emitting element 6 and the light-emitting element 7 prepared above were measured. The measurement conditions for the light-emitting elements were the same as those in the above-described examples.

[0489] FIG 28 shows current efficiency vs. luminance characteristics of the comparative light-emitting element 6 and the light-emitting element 7. FIG 29 shows current density vs. voltage characteristics. FIG 30 shows external quantum efficiency vs. luminance characteristics. 2 FIG. 31 shows the emission spectrum when a current was passed at a current density of 1000 .mu.m.

[0490] Also, 1000cd / m 2 Table 7 shows the element characteristics of the comparative light-emitting element 6 and the light-emitting element 7 in the vicinity.

[0491] [Table 7]

[0492] As can be seen from FIG. 31, the emission spectra of comparative light-emitting element 6 and light-emitting element 7 have spectral peaks at about 523 nm and 510 nm, respectively, and the full widths at half maximum are about 68 nm and 67 nm, respectively. This indicates that comparative light-emitting element 6 and light-emitting element 7 emit light originating from the guest material contained in each light-emitting element.

[0493] As shown in FIG. 28, FIG. 30, and Table 7, both the comparative light-emitting element 6 and the light-emitting element 7 exhibited high current efficiency. The light-emitting element 7 has an emission spectrum in a region with lower luminosity (short wavelength region) compared to the comparative light-emitting element 6, but has higher current efficiency than the comparative light-emitting element 6. Furthermore, as shown in FIG. 30 and Table 7, it was found that the light-emitting element 7 has extremely high efficiency, with an external quantum efficiency of more than 25%. Furthermore, the light-emitting element 7 emits light on the shorter wavelength side than the comparative light-emitting element 6 which uses GD270, which is widely used as a guest material, but exhibits higher current efficiency and external quantum efficiency than the comparative light-emitting element 6.

[0494] As shown in FIG. 29 and Table 7, it was found that each of the comparative light-emitting element 6 and the light-emitting element 7 had good driving voltage characteristics. [Explanation of symbols]

[0495] 100: EL layer, 101: electrode, 102: electrode, 103: EL layer, 106: light-emitting unit, 108: light-emitting unit, 111: hole injection layer, 112: hole transport layer, 113: electron transport layer, 114: electron injection layer, 115: charge generation layer, 116: hole injection layer, 117: hole transport layer, 118: electron transport layer, 119: electron injection layer, 120: light-emitting layer, 140: light-emitting layer, 141: host material, 141_1: organic compound, 141_2: organic compound, 142: guest material, 150: light-emitting element, 152: light-emitting element, 170: light-emitting layer, 250: light-emitting element, 601: source side driving circuit 602: pixel section, 603: gate side driving circuit, 604: sealing substrate, 605: sealing material, 607: space, 608: wiring, 610: element substrate, 611: switching TFT, 612: current control, 613: electrode, 614: insulator, 616: EL layer, 617: electrode, 618: light emitting element, 623: n-channel TFT, 624: p-channel TFT, 900: portable information terminal, 901: housing, 902: housing, 903: display section, 905: hinge section, 910: portable information terminal, 911: housing, 912: display section, 913: operation button, 914: external connection port, 91 5: speaker, 916: microphone, 917: camera, 920: camera, 921: housing, 922: display unit, 923: operation button, 924: shutter button, 926: lens, 1001: substrate, 1002: base insulating film, 1003: gate insulating film, 1006: gate electrode, 1007: gate electrode, 1008: gate electrode, 1020: interlayer insulating film, 1021: interlayer insulating film, 1022: electrode, 1024B: electrode, 1024G: electrode, 1024R: electrode, 1025B: lower electrode, 1025G: lower electrode, 1025R: lower electrode, 1026: partition wall, 1028: EL layer, 1029: electrode, 1031: sealing substrate, 1032: sealing material, 1033: base material, 1034B: colored layer, 1034G: colored layer, 1034R: colored layer, 1036: overcoat layer, 1037: interlayer insulating film, 1040: pixel section, 1041: driving circuit section, 1042: peripheral section, 2100: robot, 2101: illuminance sensor, 2102: microphone, 2103: upper camera, 2104: speaker, 2105: display, 2106: lower camera, 2107: obstacle sensor, 2108: moving mechanism, 2110: computing device, 3500: multi-function terminal, 3502: housing,3504: display unit, 3506: camera, 3508: lighting, 3600: light, 3602: housing, 3608: lighting, 3610: speaker, 5000: housing, 5001: display unit, 5002: display unit, 5003: speaker, 5004: LED lamp, 5005: operation key, 5006: connection terminal, 5007: sensor, 5008: microphone, 5012: support unit, 5013: earphone, 5100: cleaning robot, 5101: display, 510 2: camera, 5103: brush, 5104: operation button, 5120: dust, 5140: portable electronic device, 5150: mobile information terminal, 5151: housing, 5152: display area, 5153: bending portion, 8501: lighting device, 8502: lighting device, 8503: lighting device, 8504: lighting device, 9000: housing, 9001: display portion, 9006: connection terminal, 9055: hinge, 9200: mobile information terminal, 9201: mobile information terminal, 9202: mobile information terminal,

Claims

1. A pair of electrodes and a light-emitting layer are included. the light-emitting layer includes a first organic compound, a second organic compound, and an organometallic complex having a structure represented by general formula (G-1), The first organic compound and the second organic compound are a combination that forms an exciplex. 【Chemistry 1】 In general formula (G-1), R １ ~R １０ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 25 carbon atoms, a halogeno group, a cyano group, a nitro group, a carbonyl group, or a haloalkyl group, and Ar represents a substituted or unsubstituted aryl group having 6 to 25 carbon atoms.

2. A pair of electrodes and a light-emitting layer are included. the light-emitting layer comprises a first organic compound, a second organic compound, and an organometallic complex represented by general formula (G-6), The first organic compound and the second organic compound are a combination that forms an exciplex. 【Chemistry 2】 In general formula (G-6), R １ ~R １０ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 25 carbon atoms, a halogeno group, a cyano group, a nitro group, a carbonyl group, or a haloalkyl group, and Ar represents a substituted or unsubstituted aryl group having 6 to 25 carbon atoms.

3. A pair of electrodes and a light-emitting layer are included. the light-emitting layer comprises a first organic compound, a second organic compound, and an organometallic complex represented by general formula (G-11), The first organic compound and the second organic compound are a combination that forms an exciplex. 【Chemistry 3】 In general formula (G-11), R １ ~R １０ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 25 carbon atoms, a halogeno group, a cyano group, a nitro group, a carbonyl group, or a haloalkyl group, and Ar represents a substituted or unsubstituted aryl group having 6 to 25 carbon atoms. L represents a monoanionic ligand, and n represents 1 or 2.

4. A pair of electrodes and a light-emitting layer are included. the light-emitting layer includes a first organic compound, a second organic compound, and an organometallic complex having a structure represented by general formula (G-2), The first organic compound and the second organic compound are a combination that forms an exciplex. 【Chemistry 4】 In general formula (G-2), R １ ~R １５ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 25 carbon atoms, a halogeno group, a cyano group, a nitro group, a carbonyl group, or a haloalkyl group.

5. A pair of electrodes and a light-emitting layer are included. the light-emitting layer comprises a first organic compound, a second organic compound, and an organometallic complex represented by general formula (G-7), The first organic compound and the second organic compound are a combination that forms an exciplex. 【Chemistry 5】 In general formula (G-7), R １ ~R １５ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 25 carbon atoms, a halogeno group, a cyano group, a nitro group, a carbonyl group, or a haloalkyl group.

6. A pair of electrodes and a light-emitting layer are included. the light-emitting layer comprises a first organic compound, a second organic compound, and an organometallic complex represented by general formula (G-12), The first organic compound and the second organic compound are a combination that forms an exciplex. 【Chemistry 6】 In general formula (G-12), R １ ~R １５ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 25 carbon atoms, a halogeno group, a cyano group, a nitro group, a carbonyl group, or a haloalkyl group. L represents a monoanionic ligand, and n represents 1 or 2.

7. A pair of electrodes and a light-emitting layer are included. the light-emitting layer includes a first organic compound, a second organic compound, and an organometallic complex having a structure represented by general formula (G-3), The first organic compound and the second organic compound are a combination that forms an exciplex. 【Chemistry 7】 In general formula (G-3), R １１ , R １３ and R １５ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 25 carbon atoms, a halogeno group, a cyano group, a nitro group, a carbonyl group, or a haloalkyl group.

8. A pair of electrodes and a light-emitting layer are included. the light-emitting layer comprises a first organic compound, a second organic compound, and an organometallic complex represented by general formula (G-8), The first organic compound and the second organic compound are a combination that forms an exciplex. 【Chemistry 8】 In general formula (G-8), R １１ , R １３ and R １５ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 25 carbon atoms, a halogeno group, a cyano group, a nitro group, a carbonyl group, or a haloalkyl group.

9. A pair of electrodes and a light-emitting layer are included. the light-emitting layer comprises a first organic compound, a second organic compound, and an organometallic complex represented by general formula (G-13), The first organic compound and the second organic compound are a combination that forms an exciplex. 【Chemistry 9】 In general formula (G-13), R １１ , R １３ and R １５ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, a substituted or unsubstituted aryl group having 6 to 25 carbon atoms, a halogeno group, a cyano group, a nitro group, a carbonyl group, or a haloalkyl group. L represents a monoanionic ligand, and n represents 1 or 2.

10. In any one of claims 4 to 9, The R １１ and the R １５ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, １３ is hydrogen, a halogeno group, a cyano group, a nitro group, a carbonyl group, or a haloalkyl group.

11. In any one of claims 3, 6 and 9, the monoanionic ligand is a monoanionic bidentate chelate ligand having a β-diketone structure, a monoanionic bidentate chelate ligand having a carboxyl group, a monoanionic bidentate chelate ligand having a phenolic hydroxyl group, a monoanionic bidentate chelate ligand in which both of the two coordinating elements are nitrogen, or a bidentate ligand that forms a metal-carbon bond with iridium by cyclometallation.

12. In any one of claims 3, 6 and 9, The monoanionic ligand is represented by any one of the following general formulas (L1) to (L9). 【Chemistry 10】 (In the formula, R ２１ R 1 to R 87 each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a halogeno group, a vinyl group, a cyano group, a substituted or unsubstituted haloalkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 6 carbon atoms, a substituted or unsubstituted alkylthio group having 1 to 6 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 13 carbon atoms. １ or A １３ each independently represents a sp bonded to nitrogen or hydrogen ２ Hybridized carbon or substituted sp ２ represents a hybrid carbon, and the substituent represents an alkyl group having 1 to 6 carbon atoms, a halogeno group, a haloalkyl group having 1 to 6 carbon atoms, or a phenyl group.

13. In any one of claims 1 to 12, The light-emitting device, wherein the haloalkyl group is a trifluoromethyl group.

14. In any one of claims 1 to 13, The alkyl group is a branched alkyl group having 3 to 6 carbon atoms.

15. A pair of electrodes and a light-emitting layer are included. The light-emitting layer includes a first organic compound, a second organic compound, and an organometallic complex represented by any one of structural formulas (100) to (103), The first organic compound and the second organic compound are a combination that forms an exciplex. 【Chemistry 11】

16. A light-emitting element according to any one of claims 1 to 15, At least one of a color filter and a transistor; A light emitting device having the above structure.

17. A light-emitting element according to any one of claims 1 to 15, At least one of a housing and a touch sensor; An electronic device having the

18. A light-emitting element according to any one of claims 1 to 15, At least one of a housing and a touch sensor; A lighting device having the above structure.

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