Light-emitting device, light-emitting assembly, light-emitting module, electronic device, lighting device, metal-organic complex, light-emitting material, organic compound and dinuclear complex

Abstract

The emission efficiency and reliability of a light-emitting device emitting near-infrared light are increased. A light-emitting device is provided that utilizes an organic compound emitting light with a maximum peak wavelength greater than or equal to 760 nm and less than or equal to 900 nm. A metal-organic complex is provided, represented by the general formula (G1). In the formula, R1 to R11 each independently represent hydrogen or an alkyl group with 1 to 6 carbon atoms. At least two of R1 to R4 and at least two of R5 to R9 each represent an alkyl group with 1 to 6 carbon atoms. X represents a substituted or unsubstituted benzene ring or naphthalene ring, n is 2 or 3, and L represents a monoanionic ligand.

Description

Title of the invention

[0001] Light-emitting device, light-emitting device, light-emitting module, electronic device, lighting device, organometallic complex, light-emitting material, organic compound and binuclear complex Technical area

[0002] One embodiment of the present invention relates to a light-emitting device, a light-emitting device, a light-emitting module, an electronic device, a lighting device, an organometallic complex, a light-emitting material, an organic compound, and a dinuclear complex, each of which emits near-infrared light.

[0003] Note that an embodiment of the present invention is not limited to the above technical field. Examples of the technical field of an embodiment of the present invention include a semiconductor device, a display device, a light-emitting device, a power storage device, a memory device, an electronic device, a lighting device, an input device (e.g., a touch sensor), an input / output device (e.g., a touch screen), an operation method thereof, and a manufacturing method thereof. State of the art

[0004] Research and development have been actively conducted on light-emitting devices that utilize the organic electroluminescence (EL) phenomenon (also referred to as organic EL devices or organic EL elements). In the basic structure of an organic EL device, a layer containing a light-emitting organic compound (hereinafter also referred to as a light-emitting layer) is sandwiched between a pair of electrodes. By applying a voltage to the organic EL device, light emission from the light-emitting organic compound can be obtained.

[0005] An example of the light-emitting organic compound includes a compound capable of converting a triplet excited state into light emission (also referred to as a phosphorescent compound or phosphorescent material). As the phosphorescent material, Patent Document 1 discloses an organometallic complex containing iridium or the like as the central metal.

[0006] Image sensors are used for various purposes, such as personal authentication, failure analysis, medical diagnosis, and security. The wavelengths of light sources used for image sensors vary depending on the purpose. Light with different wavelengths, for example, short-wavelength light, such as visible light and X-rays, and long-wavelength light, such as near-infrared light, are used for image sensors.

[0007] It has also been considered that light-emitting devices could be applied to the above-described light sources of image sensors, in addition to display devices. CN 1 03 665 048 B discloses a metal complex and its use in an organic light-emitting device. CHEN, Hsing-Yi [et al.] discloses the development and synthesis of a series of iridium complexes. [Reference][Patent document] [Patent Document 1] Japanese Patent Application Laid-Open No. JP 2007 - 137 872 A [Patent Document 2] CN 1 03 665 048 B [Patent Document 3] CHEN, Hsing-Yi [et al.]: Room-temperature NIR phosphorescence of new iridium (III) complexes with ligands derived from benzoquinoxaline. In: Canadian journal of chemistry, Vol. 84, 2006, No. 2, pp. 309-318. Summary of the inventionProblem to be solved by the invention

[0008] An object of one embodiment of the present invention is to increase the emission efficiency of a light-emitting device that emits near-infrared light. An object of one embodiment of the present invention is to increase the reliability of a light-emitting device that emits near-infrared light. An object of one embodiment of the present invention is to extend the lifetime of a light-emitting device that emits near-infrared light.

[0009] An object of one embodiment of the present invention is to provide an organometallic complex with high emission efficiency. An object of one embodiment of the present invention is to provide an organometallic complex with high chemical stability. An object of one embodiment of the present invention is to provide a novel organometallic complex that emits near-infrared light. An object of one embodiment of the present invention is to provide a novel organometallic complex that can be used in an EL layer of a light-emitting device.

[0010] It should be noted that the description of these objects does not preclude the existence of further objects. In one embodiment of the present invention, it is not necessarily required to fulfill all of these objects. Further objects may be derived from the explanation of the description, the drawings, and the claims. Means to solve the problem

[0011] One embodiment of the present invention is a light-emitting device (also referred to as a light-emitting element) that includes a light-emitting layer. The light-emitting layer includes a light-emitting organic compound. The maximum peak wavelength (also referred to as the wavelength at which the peak intensity is highest) of light emitted by the light-emitting organic compound is greater than or equal to 760 nm and less than or equal to 900 nm.

[0012] One embodiment of the present invention is a light-emitting device including a first electrode, a second electrode, and a light-emitting layer. The light-emitting layer is positioned between the first electrode and the second electrode. The light-emitting layer includes a light-emitting organic compound. The maximum peak wavelength of light emitted by the light-emitting organic compound is greater than or equal to 760 nm and less than or equal to 900 nm.

[0013] The maximum peak wavelength of light emitted from the light-emitting organic compound is preferably greater than or equal to 780 nm. Further, the maximum peak wavelength of light emitted from the light-emitting organic compound is preferably less than or equal to 880 nm.

[0014] The light-emitting organic compound is preferably an organometallic complex having a metal-carbon bond. Among them, the light-emitting organic compound is more preferably a cyclometallic complex. Further, the light-emitting organic compound is preferably an orthometallic complex. Further, the light-emitting organic compound is preferably an iridium complex. When the light-emitting organic compound is an organometallic complex having a metal-carbon bond, it is preferable that the organometallic complex comprises a condensed heteroaromatic ring comprising 2 to 5 rings, and the condensed heteroaromatic ring is coordinated to a metal. The condensed heteroaromatic ring preferably comprises 3 or more rings. Further, the condensed heteroaromatic ring preferably comprises 4 or fewer rings.

[0015] An embodiment of the present invention is a light-emitting device including the light-emitting device having any of the above structures and a transistor and / or a substrate.

[0016] One embodiment of the present invention is a light-emitting module including the light-emitting device described above. The light-emitting module is provided with a connector such as a flexible printed circuit (hereinafter referred to as FPC) or a tape carrier package (TCP), or is mounted with an integrated circuit (IC) by a chip-on-glass (COG) method, a chip-on-film (COF) method, or the like. Note that the light-emitting module of one embodiment of the present invention may include a connector and / or an IC.

[0017] An embodiment of the present invention is an electronic device including the above-described light-emitting module and an antenna, a battery, a housing, a camera, a speaker, a microphone, and / or a control button.

[0018] One embodiment of the present invention is a lighting device including the above-described light-emitting device and a housing, a cover, and / or a support base.

[0019] One embodiment of the present invention is an organometallic complex represented by the general formula (G1). Another embodiment of the present invention is a light-emitting material represented by the general formula (G1). Another embodiment of the present invention is a material for a light-emitting device represented by the general formula (G1).

[0020] In the general formula (G1), R 1 to R 11 each independently represents hydrogen or an alkyl group having 1 to 6 carbon atoms. At least two of R 1 to R 4 each represent an alkyl group having 1 to 6 carbon atoms. At least two of R 5 to R 9 each represents an alkyl group having 1 to 6 carbon atoms. X represents a substituted or unsubstituted benzene ring or naphthalene ring, n is 2 or 3, and L represents a monoanionic ligand.

[0021] One embodiment of the present invention is an organometallic complex represented by the general formula (G2). Another embodiment of the present invention is a light-emitting material represented by the general formula (G2). Another embodiment of the present invention is a material for a light-emitting device represented by the general formula (G2).

[0022] In the general formula (G2) R 1 , R 3 , R 6 and R 8 each independently represents an alkyl group having 1 to 6 carbon atoms. R 10 and R 11 each independently represents hydrogen or an alkyl group having 1 to 6 carbon atoms. X represents a substituted or unsubstituted benzene ring or naphthalene ring, n is 2 or 3, and L represents a monoanionic ligand.

[0023] The maximum peak wavelength of light emitted from the organometallic complex, the light-emitting material, or the material for a light-emitting device of one embodiment of the present invention is preferably greater than or equal to 760 nm and less than or equal to 900 nm.

[0024] One embodiment of the present invention is a light-emitting device including a light-emitting layer. The light-emitting layer includes an organometallic complex, a light-emitting material, or a material for a light-emitting device, each having one of the structures described above. The light-emitting device has a function of emitting light whose maximum peak wavelength is greater than or equal to 760 nm and less than or equal to 900 nm.

[0025] One embodiment of the present invention is an organic compound represented by the general formula (G0).

[0026] In the general formula (G0) R 1 to R 11 each independently represents hydrogen or an alkyl group having 1 to 6 carbon atoms. At least two of R 1 to R 4 each represent an alkyl group having 1 to 6 carbon atoms. At least two of R 5 to R 9 each represents an alkyl group having 1 to 6 carbon atoms. X represents a substituted or unsubstituted benzene ring or naphthalene ring.

[0027] One embodiment of the present invention is an organic compound represented by the structural formula (200).

[0028] One embodiment of the present invention is a binuclear complex represented by the general formula (B).

[0029] In the general formula (B), Z represents a halogen. R 1 to R 11 each independently represents hydrogen or an alkyl group having 1 to 6 carbon atoms. At least two of R 1 to R 4 each represent an alkyl group having 1 to 6 carbon atoms. At least two of R 5 to R 9 each represents an alkyl group having 1 to 6 carbon atoms. X represents a substituted or unsubstituted benzene ring or naphthalene ring.

[0030] One embodiment of the present invention is a binuclear complex represented by the structural formula (210). Effect of the invention

[0031] An embodiment of the present invention can increase the emission efficiency of a light-emitting device that emits near-infrared light. An embodiment of the present invention can increase the reliability of a light-emitting device that emits near-infrared light. An embodiment of the present invention can extend the lifetime of a light-emitting device that emits near-infrared light.

[0032] An embodiment of the present invention can provide an organometallic complex with high emission efficiency. An embodiment of the present invention can provide an organometallic complex with high chemical stability. An embodiment of the present invention can provide a novel organometallic complex that emits near-infrared light. An embodiment of the present invention can provide a novel organometallic complex that can be used in an EL layer of a light-emitting device.

[0033] It should be noted that the description of these effects does not preclude the existence of further effects. In one embodiment of the present invention, it is not necessarily required to achieve all of the effects. Further effects can be derived from the explanation of the description, the drawings, and the claims. Short description of the drawings Fig. 1A, Fig. 1B and Fig. 1C are cross-sectional views illustrating examples of light-emitting devices. Fig. 2A is a plan view showing an example of a light-emitting device. Fig. 2B and Fig. 2C are cross-sectional views showing examples of the light-emitting device. Fig. 3A is a plan view showing an example of a light-emitting device. Fig. 3B is a cross-sectional view showing an example of the light-emitting device. Fig. 4A to Fig. 4E are diagrams showing examples of electronic devices. Fig. 5 is a 1 H-NMR diagram of the organic compound represented by the structural formula (200). Fig. 6 is a1 H-NMR diagram of an organometallic complex represented by the structural formula (100). Fig. Figure 7 shows a UV-VIS absorption spectrum and an emission spectrum of the organometallic complex represented by the structural formula (100). Fig. Figure 8 is a graph showing the weight change rate of the organometallic complex represented by the structural formula (100). Fig. 9A and Fig. 9B are cross-sectional views illustrating light-emitting devices of examples. Fig. 10 is a graph showing the current density-radiance characteristics of a light-emitting device 1. Fig. 11 is a graph showing the voltage-current density characteristics of the light-emitting device 1. Fig.12 is a graph showing the current density-radiant power characteristics of the light-emitting device 1. Fig. 13 is a graph showing the voltage-radiance characteristics of the light-emitting device 1. Fig. 14 is a diagram showing the current density-external quantum efficiency characteristics of the light-emitting device 1. Fig. 15 is a diagram showing an emission spectrum of the light-emitting device 1. Fig. 16 is a diagram showing the results of a reliability test of the light-emitting device 1. Fig. 17 is a graph showing the current density-radiance characteristics of a light-emitting device 2. Fig. 18 is a graph showing the voltage-current density characteristics of the light-emitting device 2. Fig.19 is a graph showing the current density-radiant power characteristics of the light-emitting device 2. Fig. 20 is a graph showing the voltage-radiance characteristics of the light-emitting device 2. Fig. 21 is a diagram showing the current density-external quantum efficiency characteristics of the light-emitting device 2. Fig. 22 is a diagram showing an emission spectrum of the light-emitting device 2. Fig. 23 is a diagram showing the results of a reliability test of the light-emitting device 2. Fig. 24 is a graph showing the current density-radiance characteristics of a light-emitting device 3. Fig. 25 is a graph showing the voltage-current density characteristics of the light-emitting device 3. Fig.26 is a graph showing the current density-radiant power characteristics of the light-emitting device 3. Fig. Fig. 27 is a graph showing the voltage-radiance characteristics of the light-emitting device 3. Fig. 28 is a diagram showing the current density-external quantum efficiency characteristics of the light-emitting device 3. Fig. 29 is a diagram showing an emission spectrum of the light-emitting device 3. Fig. 30 is a diagram showing the results of a reliability test of the light-emitting device 3. Fig. 31 is a diagram showing the angle dependence of the relative intensity of the light-emitting device 3. Fig. 32 is a diagram showing the angle dependence of the normalized photon intensity of the light-emitting device 3. Embodiments of the invention

[0034] Embodiments are described in detail using the drawings.

[0035] In the structures of the invention described below, the same sections or sections with similar functions are designated by the same reference numerals in different drawings, and the description thereof will not be repeated. The same hatching pattern is used for sections with similar functions, and in some cases, the sections are not designated by specific reference numerals.

[0036] Furthermore, the position, size, range, or the like of each component illustrated in the drawings is sometimes not precisely illustrated for ease of understanding. Therefore, the disclosed invention is not necessarily limited to the position, size, range, or the like disclosed in the drawings.

[0037] It should be noted that the term "film" and "layer" may be interchangeable depending on the situation or circumstances. For example, the term "conductive layer" may be replaced by the term "conductive film." For example, the term "insulating film" may also be replaced by the term "insulating layer." (Embodiment 1)

[0038] In this embodiment, an organometallic complex of one embodiment of the present invention is described. [Structure of the organometallic complex of one embodiment of the present invention]

[0039] The organometallic complex of one embodiment of the present invention has a structure in which a ligand having a benzoquinoxaline skeleton or a naphthoquinoxaline skeleton is bonded to iridium, which is a central metal. Specifically, one embodiment of the present invention is an organometallic complex represented by the general formula (G1). Another embodiment of the present invention is a light-emitting material represented by the general formula (G1). Another embodiment of the present invention is a material for a light-emitting device represented by the general formula (G1).

[0040] In the general formula (G1), R 1 to R 11 each independently represents hydrogen or an alkyl group having 1 to 6 carbon atoms. At least two of R 1 to R 4each represent an alkyl group having 1 to 6 carbon atoms. At least two of R 5 to R 9 each represents an alkyl group having 1 to 6 carbon atoms. X represents a substituted or unsubstituted benzene ring or naphthalene ring, n is 2 or 3, and L represents a monoanionic ligand.

[0041] In the general formula (G1), X is a substituted or unsubstituted benzene ring or naphthalene ring. A benzene ring or a naphthalene ring is condensed with quinoxaline, which allows the π-conjugated system to expand, the lowest unoccupied molecular orbital (LUMO) level to become lower, and energetic stability to be maintained. Therefore, the emission wavelength can be long. Consequently, an organometallic complex that emits near-infrared light can be obtained.

[0042] One embodiment of the present invention is an organometallic complex represented by the general formula (G2). Another embodiment of the present invention is a light-emitting material represented by the general formula (G2). Another embodiment of the present invention is a material for a light-emitting device represented by the general formula (G2).

[0043] In the general formula (G2) R 1 , R 3 , R 6 and R 8 each independently represents an alkyl group having 1 to 6 carbon atoms. R 10 and R 11 each independently represents hydrogen or an alkyl group having 1 to 6 carbon atoms. X represents a substituted or unsubstituted benzene ring or naphthalene ring, n is 2 or 3, and L represents a monoanionic ligand.

[0044] In the general formula (G2), X is a substituted or unsubstituted benzene ring or naphthalene ring. This means that a benzene ring or a naphthalene ring is condensed with quinoxaline, which allows the π-conjugated system to expand, the LUMO level to become deeper, and energetic stability to be maintained. Therefore, the emission wavelength can be a long wavelength. Consequently, an organometallic complex that emits near-infrared light can be obtained.

[0045] R 1 , R 3 , R 6 and R 8 are each preferably an alkyl group having 1 to 6 carbon atoms, since compared to the case where R 1 , R 3 , R 6 and R 8 are each hydrogen, the sublimability of the organometallic complex can be increased and the sublimation temperature can be reduced. In particular, R 1 , R 3 , R 6 and R 8each preferably a methyl group. In other words: R 1 , R 3 , R 6 and R 8 are all preferably methyl groups.

[0046] In one embodiment of the present invention, X is a substituted or unsubstituted benzene ring or naphthalene ring; therefore, the sublimability of the organometallic complex is more likely to be reduced compared to the case where X is not a condensed ring. However, since R 1 , R 3 , R 6 and R 8 are each an alkyl group with 1 to 6 carbon atoms, the sublimability of the organometallic complex can be increased. Thus, an organometallic complex can be obtained that exhibits high sublimability and emits near-infrared light.

[0047] If R 1 and R 3are each an alkyl group having 1 to 6 carbon atoms, the dihedral angle of the benzene ring bonded to iridium can be increased. Consequently, a second peak of an emission spectrum of the organometallic complex can theoretically be reduced, so that the half-width can be narrowed. Consequently, light with a desired wavelength can be efficiently obtained.

[0048] Examples of the alkyl group having 1 to 6 carbon atoms in the general formulas (G1) and (G2) include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a neopentyl group, a hexyl group, an isohexyl group, a 3-methylpentyl group, a 2-methylpentyl group, a 2-ethylbutyl group, a 1,2-dimethylbutyl group and a 2,3-dimethylbutyl group.

[0049] In the case where the benzene ring or the naphthalene ring in general formulas (G1) and (G2) has a substituent, an alkyl group having 1 to 6 carbon atoms can be specified as the substituent. Regarding the alkyl group having 1 to 6 carbon atoms, reference can be made to the above description.

[0050] Examples of the monoanionic ligand include 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 two ligand elements are each nitrogen, and a bidentate ligand that forms a metal-carbon bond with iridium by cyclometalation.

[0051] The monoanionic ligand is preferably represented by any one of the general formulas (L1) to (L7). In particular, the ligand represented by the general formula (L1) is preferably used because the sublimability is increased. Furthermore, the combination of the ligand (dipivaloylmethane) represented by the structural formula (L8), which is an example of the ligand represented by the general formula (L1), and the ligand having a benzoquinoxaline skeleton or a naphthoquinoxaline skeleton is suitable and preferable because the sublimability of the organometallic complex of one embodiment of the present invention can be increased and the sublimation temperature can be reduced.

[0052] In the general formulas (L1) to (L7) R 51 to R 89each independently represents hydrogen, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a halogeno group, a vinyl 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. A 1 to A 13 each independently represent nitrogen, sp 2 -hybridized carbon bonded to hydrogen, or sp 2 -hybridized carbon with a substituent. The substituent is 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.

[0053] The maximum peak wavelength (i.e., the wavelength at which the peak intensity is highest) of light emitted from the organometallic complex of one embodiment of the present invention is preferably greater than or equal to 760 nm and less than or equal to 900 nm. In particular, the wavelength is preferably greater than or equal to 780 nm. Further, the wavelength is preferably less than or equal to 880 nm.

[0054] Specific examples of the organometallic complex of one embodiment of the present invention include organometallic complexes represented by structural formulas (100) to (111). Note that the present invention is not limited to these examples. [Synthesis method of the organometallic complex of one embodiment of the present invention]

[0055] Various reactions can be applied to a synthesis method of the organometallic complex of one embodiment of the present invention. As an example, a method for synthesizing the organometallic complex represented by general formula (G1) is shown below.

[0056] First, an example of a method for synthesizing the organic compound represented by the general formula (G0) will be described. Then, a method for synthesizing the organometallic complex represented by the general formula (G1) using the organic compound represented by the general formula (G0) will be described. Note that the following two cases will be described separately below: the case where n in the general formula (G1) is 2 (the organometallic complex represented by the general formula (G1-1)) and the case where n in the general formula (G1) is 3 (the organometallic complex represented by the general formula (G1-2)). Note that the method for synthesizing the organometallic complex of one embodiment of the present invention is not limited to the following synthesis methods. < <Beispiel für ein Verfahren zum Synthetisieren der organischen Verbindung, die durch die allgemeine Formel (G0) dargestellt wird> >

[0057] The organic compound represented by the general formula (G0) is a type of quinoxaline derivative and the organic compound of one embodiment of the present invention. The organic compound represented by the general formula (G0) can be synthesized, for example, by one of the following three synthesis schemes (A-1), (A-1'), and (A-1").

[0058] In the general formula (G0) and the synthesis schemes (A-1), (A-1') and (A-1") to be described below, R 1 to R 11 each independently represents hydrogen or an alkyl group having 1 to 6 carbon atoms. At least two of R 1 to R 4 each represent an alkyl group having 1 to 6 carbon atoms. At least two of R5 to R 9 each represents an alkyl group having 1 to 6 carbon atoms, and X represents a substituted or unsubstituted benzene ring or naphthalene ring.

[0059] For example, as shown in the synthesis scheme (A-1), the organic compound represented by the general formula (G0) can be obtained by lithiating a halogenated benzene derivative (A1) with alkyllithium or the like and reacting with a quinoxaline derivative (A2). Note that in the synthesis scheme (A-1), Z 1 is a halogen.

[0060] Furthermore, as shown in the synthesis scheme (A-1'), the organic compound represented by the general formula (G0) can be obtained by coupling a boronic acid (A1') of a benzene derivative with a halide (A2') of quinoxaline. Note that in the synthesis scheme (A-1'), Z 2is a halogen.

[0061] In addition, as shown in the synthesis scheme (A-1"), the organic compound represented by the general formula (G0) can be obtained by reacting diketone with benzene derivatives as substituents (A1") with diamine (A2").

[0062] The method for synthesizing the organic compound represented by the general formula (G0) is not limited to the three synthesis methods described above, and another synthesis method may be used.

[0063] Since various kinds of the above compounds (A1), (A2), (A1'), (A2'), (A1") and (A2") are commercially available or can be synthesized, various kinds of the organic compounds represented by the general formula (G0) can be synthesized. Accordingly, a feature of the organometallic complex of one embodiment of the present invention is the abundance of ligand variations. < <Verfahren zum Synthetisieren des metallorganischen Komplexes, der durch die allgemeine Formel (G1-1) dargestellt wird> >

[0064] Next, an example of a method for synthesizing the organometallic complex represented by general formula (G1-1) will be described. The organometallic complex represented by general formula (G1-1) is the organometallic complex of one embodiment of the present invention and corresponds to the case where n in general formula (G1) is 2.

[0065] In the general formula (G1-1) and the synthesis schemes (A-2) and (A-3) to be described below, R 1 to R 11 each independently represents hydrogen or an alkyl group having 1 to 6 carbon atoms. At least two of R 1 to R 4 each represent an alkyl group having 1 to 6 carbon atoms. At least two of R 5 to R 9each represents an alkyl group having 1 to 6 carbon atoms. X represents a substituted or unsubstituted benzene ring or naphthalene ring, and L represents a monoanionic ligand.

[0066] As shown in the synthesis scheme (A-2), first, the organic compound represented by the general formula (G0) and an iridium compound containing a halogen (e.g., iridium chloride, iridium bromide, or iridium iodide) are heated in an inert gas atmosphere without using a solvent, using only an alcohol-based solvent (e.g., glycerin, ethylene glycol, 2-methoxyethanol, or 2-ethoxyethanol), or using a mixed solvent of water and one or more of the alcohol-based solvents, whereby the dinuclear complex represented by the general formula (B) can be obtained. There is no particular limitation on a heating means, and an oil bath, a sand bath, or an aluminum block can be used. Alternatively, microwaves can be used as the heating means.

[0067] The binuclear complex represented by the general formula (B) is a kind of organometallic complex having a halogen-bonded structure, that is, a binuclear complex of one embodiment of the present invention.

[0068] Furthermore, as shown in the synthesis scheme (A-3), the dinuclear complex represented by the general formula (B) reacts with HL, which is a material of the monoanionic ligand, in an inert gas atmosphere, thereby removing a proton from HL and coordinating L to the central metal (Ir). In this way, the organometallic complex represented by the general formula (G1-1) can be obtained. There is no particular limitation on a heating medium, and an oil bath, a sand bath, or an aluminum block can be used. Alternatively, microwaves can be used as the heating medium.

[0069] It should be noted that in the synthesis schemes (A-2) and (A-3) Z represents a halogen. < <Verfahren zum Synthetisieren des metallorganischen Komplexes, der durch die allgemeine Formel (G1-2) dargestellt wird> >

[0070] Next, an example of a method for synthesizing the organometallic complex represented by general formula (G1-2) will be described. The organometallic complex represented by general formula (G1-2) is the organometallic complex of one embodiment of the present invention and corresponds to the case where n in general formula (G1) is 3.

[0071] In the general formula (G1-2) and the synthesis scheme (A-4) to be described below, R 1 to R 11 each independently represents hydrogen or an alkyl group having 1 to 6 carbon atoms. At least two of R 1 to R 4each represent an alkyl group having 1 to 6 carbon atoms. At least two of R 5 to R 9 each represents an alkyl group having 1 to 6 carbon atoms, and X represents a substituted or unsubstituted benzene ring or naphthalene ring.

[0072] As shown in the synthesis scheme (A-4), the organometallic complex represented by the general formula (G1-2) can be obtained in the following manner: an iridium compound containing a halogen (e.g., iridium chloride hydrate, iridium bromide, iridium iodide, iridium acetate, or ammonium hexachloroiridate) or an organoiridium complex (e.g., an acetylacetonato complex, a diethyl sulfide complex, a bridged binuclear di-μ-chloro complex, or a bridged binuclear di-μ-hydroxo complex) is mixed with the organic compound represented by the general formula (G0), the mixture is dissolved in an alcohol-based solvent (e.g., glycerin, ethylene glycol, 2-methoxyethanol, or 2-ethoxyethanol) or not dissolved in a solvent, and heating is carried out.

[0073] The methods for synthesizing the organometallic complex of one embodiment of the present invention are described above; however, the present invention is not limited thereto, and another synthesis method may be employed.

[0074] As described above, the organometallic complex of one embodiment of the present invention emits near-infrared light and has high sublimability. Therefore, the organometallic complex is suitable for a light-emitting material and a light-emitting device material, each of which emits near-infrared light. By using the organometallic complex of one embodiment of the present invention, the emission efficiency of a light-emitting device that emits near-infrared light can be increased. Furthermore, by using the organometallic complex of one embodiment of the present invention, the reliability of a light-emitting device that emits near-infrared light can be increased.

[0075] This embodiment can be combined with the other embodiments as needed. Where a plurality of structural examples are shown in one embodiment in this specification, the structural examples can be combined as needed. (Embodiment 2)

[0076] In this embodiment, a light-emitting device of an embodiment of the present invention and a light-emitting device of an embodiment of the present invention are described with reference to Fig. 1 to Fig. 3 described.

[0077] The light-emitting device of one embodiment of the present invention includes a light-emitting organic compound in a light-emitting layer. The maximum peak wavelength (also referred to as the wavelength at which the peak intensity is highest) of light emitted by the light-emitting organic compound is greater than or equal to 760 nm and less than or equal to 900 nm, preferably greater than or equal to 780 nm and preferably less than or equal to 880 nm.

[0078] The light-emitting device of one embodiment of the present invention can be formed in the form of a film, and the area is easily increased; therefore, it can be used as a planar light source that emits near-infrared light.

[0079] The light-emitting organic compound preferably emits phosphorescence because the emission efficiency of the light-emitting device can be increased. In particular, the light-emitting organic compound is preferably an organometallic complex having a metal-carbon bond. Among them, the light-emitting organic compound is more preferably a cyclometalated complex. Further, the light-emitting organic compound is preferably an orthometalated complex. Since these organic compounds readily emit phosphorescence, the emission efficiency of the light-emitting device can be increased. Accordingly, the light-emitting device of one embodiment of the present invention is preferably a phosphorescent device that emits phosphorescence.

[0080] Furthermore, the organometallic complex having a metal-carbon bond is suitable for a light-emitting organic compound because it has higher emission efficiency and higher chemical stability than a porphyrin-based compound or the like.

[0081] In the case where a light-emitting organic compound is used as a guest material in a light-emitting layer and another organic compound is used as a host material, if a deep valley appears in the absorption spectrum of the light-emitting organic compound (a low-intensity portion appears), depending on the excitation energy value of the host material, the energy is not easily transferred from the host material to the guest material, and the energy transfer efficiency is reduced. In the absorption spectrum of the organometallic complex having a metal-carbon bond, many absorption bands overlap, such as the α- and α-bands.An absorption band resulting from a triplet metal-to-ligand charge transfer (MLCT) transition, an absorption band resulting from a singlet MLCT transition, and an absorption band resulting from a triplet π-π* transition overlap each other; therefore, a deep valley is less likely to appear in the absorption spectrum. Thus, the range of excitation energy values ​​of the material that can be used as a host material can be expanded, and the host material selection options can be increased.

[0082] Furthermore, the light-emitting organic compound is preferably an iridium complex. For example, the light-emitting organic compound is preferably a cyclometalated complex using iridium as the central metal. Since the iridium complex has higher chemical stability than a platinum complex or the like, using the iridium complex as the light-emitting organic compound enables the reliability of the light-emitting device to be increased. In view of such stability, a cyclometalated complex of iridium is preferred, and an orthometalated complex of iridium is more preferred.

[0083] From the viewpoint of obtaining near-infrared light emission, the ligand of the above organometallic complex preferably has a structure in which a condensed heteroaromatic ring comprising 2 to 5 rings is coordinated to a metal. The condensed heteroaromatic ring preferably comprises 3 or more rings. Furthermore, the condensed heteroaromatic ring preferably comprises 4 or fewer rings. When the number of rings contained in the condensed heteroaromatic ring is increased, the LUMO level can be lowered and the emission wavelength of the organometallic complex can be a long wavelength. When the number of condensed heteroaromatic rings is reduced, sublimability can be increased.By using a fused heteroaromatic ring comprising 2 to 5 rings, the LUMO level of the ligand is appropriately reduced, so that the emission wavelength of the organometallic complex based on a (triplet) MLCT transition can be increased to the near-infrared wavelength while maintaining high sublimability. Furthermore, by increasing the number of nitrogen atoms (N) contained in the fused heteroaromatic ring, the LUMO level can be reduced. Accordingly, the number of nitrogen atoms (N) contained in the fused heteroaromatic ring is preferably 2 or more, more preferably 2. [Structural example of a light-emitting device]<<Grundlegende Struktur einer Licht emittierenden Vorrichtung> >

[0084] Fig. 1A to Fig.1C illustrate examples of light-emitting devices that include an EL layer between a pair of electrodes.

[0085] The light-emitting device used in Fig. 1A has a structure in which an EL layer 103 is provided between a first electrode 101 and a second electrode 102 (a single structure). The EL layer 103 includes at least one light-emitting layer.

[0086] The light-emitting device may include a plurality of EL layers between a pair of electrodes. Fig.Figure 1B illustrates a light-emitting device with a tandem structure in which two EL layers (EL layers 103a and 103b) are provided between a pair of electrodes, and a charge generation layer 104 is provided between the two EL layers. The light-emitting device with a tandem structure can operate at a low voltage and has low power consumption.

[0087] The charge generation layer 104 has a function of injecting electrons into one of the EL layer 103a and the EL layer 103b and injecting holes into the other of the EL layers when a voltage is applied to the first electrode 101 and the second electrode 102. Therefore, the charge generation layer 104 injects electrons into the EL layer 103a and holes into the EL layer 103b when Fig.1B, a voltage is applied to the first electrode 101 such that the potential of the first electrode 101 is higher than that of the second electrode 102.

[0088] Note that, in terms of light extraction efficiency, the charge generation layer 104 preferably transmits near-infrared light (specifically, the near-infrared light transmittance of the charge generation layer 104 is preferably 40% or higher). Furthermore, the charge generation layer 104 operates even if it has a lower conductivity than the first electrode 101 or the second electrode 102.

[0089] Fig.1C illustrates an example of a multilayer structure of the EL layer 103. In this embodiment, an example will be described in which the first electrode 101 serves as an anode and the second electrode 102 serves as a cathode. The EL layer 103 has a structure in which a hole injection layer 111, a hole transport layer 112, a light-emitting layer 113, an electron transport layer 114, and an electron injection layer 115 are arranged in this order above the first electrode 101. The hole injection layer 111, the hole transport layer 112, the light-emitting layer 113, the electron transport layer 114, and the electron injection layer 115 may each have a single-layer structure or a multilayer structure. Even in the case where a plurality of EL layers are arranged as in the Fig.1B, the EL layers may each have a multilayer structure similar to that of the tandem structure shown in Fig. 1C. In the case where the first electrode 101 serves as the cathode and the second electrode 102 serves as the anode, the arrangement order is reversed.

[0090] The light-emitting layer 113 contains a light-emitting substance and a plurality of substances in a suitable combination so that fluorescence or phosphorescence with a desired wavelength can be obtained. The light-emitting layer 113 may further have a multilayer structure composed of layers with different emission wavelengths. In this case, the light-emitting substance and other substances are different between the stacked light-emitting layers. In addition, the Fig.1B emit light at different wavelengths. In this case, too, the light-emitting substances and other substances between the light-emitting layers are different.

[0091] The light-emitting device of one embodiment of the present invention may have such a structure that light emitted from the EL layer is resonated between the pair of electrodes to amplify the light. For example, in Fig. 1C, an optical microresonator (microcavity) structure in which the first electrode 101 is a reflective electrode and the second electrode 102 is a transflective electrode (an electrode having a transmitting property and a reflecting property with respect to near-infrared light) is used, whereby light emitted from the EL layer 103 can be amplified.

[0092] Note that in the case where the first electrode 101 of the light-emitting device is a reflective electrode having a multilayer structure composed of a conductive film having a reflection property with respect to near-infrared light and a conductive film having a transmission property with respect to near-infrared light, optical matching can be performed by controlling the thickness of the conductive film having a transmission property. Specifically, when the wavelength of light emitted from the light-emitting layer 113 is λ, the distance between the first electrode 101 and the second electrode 102 is preferably set to about mλ / 2 (m is a natural number).

[0093] In order to amplify desired light (wavelength: λ) obtained from the light-emitting layer 113, it is preferable to set the optical path length from the first electrode 101 to a region of the light-emitting layer 113 where the desired light is obtained (light-emitting region) and the optical path length from the second electrode 102 to a region of the light-emitting layer 113 where the desired light is obtained (light-emitting region) to approximately (2m'+1)λ / 4 (m' is a natural number), respectively. Here, the light-emitting region refers to a region of the light-emitting layer 113 where holes and electrons recombine.

[0094] By such optical adjustment, the spectrum of light emitted from the light-emitting layer 113 can be narrowed and light emission with a desired wavelength can be obtained.

[0095] In the above case, the optical path length between the first electrode 101 and the second electrode 102 is specifically the total thickness from a reflection region in the first electrode 101 to a reflection region in the second electrode 102. However, it is difficult to accurately determine the reflection regions in the first electrode 101 and the second electrode 102; therefore, it is assumed that the above effect can be sufficiently achieved regardless of the location of the reflection regions in the first electrode 101 and the second electrode 102. Furthermore, the optical path length between the first electrode 101 and the light-emitting layer that emits the desired light may be specifically the optical path length between the reflection region in the first electrode 101 and the light-emitting region in the light-emitting layer that emits the desired light.However, it is difficult to accurately determine the reflection area in the first electrode 101 and the light-emitting area in the light-emitting layer that emits the desired light; therefore, it is assumed that the above effect can be sufficiently achieved no matter where the reflection area in the first electrode 101 and the light-emitting area in the light-emitting layer that emits the desired light are located.

[0096] The first electrode 101 and / or the second electrode 102 have / have a transmittance property with respect to near-infrared light. The near-infrared light transmittance of the electrode with a transmittance property with respect to near-infrared light is higher than or equal to 40%. In the case where the electrode with a transmittance property with respect to near-infrared light is the above transflective electrode, the near-infrared light reflectance of the electrode is higher than or equal to 20%, preferably higher than or equal to 40% and lower than 100%, preferably lower than or equal to 95%; alternatively, it may be lower than or equal to 80% or lower than or equal to 70%. For example, the near-infrared light reflectance of the electrode is higher than or equal to 20% and lower than or equal to 80%, preferably higher than or equal to 40% and lower than or equal to 70%.This electrode preferably has a specific resistance of 1 × 10. -2 Ωcm or less.

[0097] When the first electrode 101 or the second electrode 102 is an electrode having a reflection property with respect to near-infrared light (reflective electrode), the near-infrared light reflectance of the reflective electrode is higher than or equal to 40% and lower than or equal to 100%, preferably higher than or equal to 70% and lower than or equal to 100%. This electrode preferably has a specific resistance of 1 × 10 -2 Ωcm or less. <<Spezifische Struktur und Herstellungsverfahren der Licht emittierenden Vorrichtung> >

[0098] Next, a specific structure and a manufacturing method of the light-emitting device are described. Here, the light-emitting device with the single structure is Fig. 1C used for the description. <Erste Elektrode und zweite Elektrode>

[0099] As materials for forming the first electrode 101 and the second electrode 102, any of the following materials can be used in a suitable combination as long as the functions of the two electrodes described above can be fulfilled. For example, a metal, an alloy, an electrically conductive compound, a mixture of these, and the like can be suitably used. Specifically, an In-Sn oxide (also referred to as ITO), an In-Si-Sn oxide (also referred to as ITSO), an In-Zn oxide, an In-W-Zn oxide, or the like can be specified. In addition, it is possible to use a metal such asAluminum (Al), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), gallium (Ga), zinc (Zn), indium (In), tin (Sn), molybdenum (Mo), tantalum (Ta), tungsten (W), palladium (Pd), gold (Au), platinum (Pt), silver (Ag), yttrium (Y), or neodymium (Nd), or an alloy containing a suitable combination of any of these metals. It is also possible to use a Group 1 or Group 2 element of the periodic table not described above (e.g., lithium (Li), cesium (Cs), calcium (Ca), or strontium (Sr)), a rare earth metal such as europium (Eu) or ytterbium (Yb), an alloy containing a suitable combination of any of these, graphene, or the like.

[0100] Note that when manufacturing a light-emitting device with a microcavity structure, the first electrode 101 is formed as a reflective electrode, and the second electrode 102 is formed as a transflective electrode. Therefore, a single-layer structure or a multi-layer structure can be formed using one or more types of desired conductive materials. Note that the second electrode 102 is formed after the formation of the EL layer 103, and a material is selected as described above. A sputtering method or a vacuum evaporation method can be used to manufacture these electrodes.

[0101] At the Fig.In the light-emitting device shown in Fig. 1C, when the first electrode 101 is an anode, the hole injection layer 111 and the hole transport layer 112 are sequentially disposed over the first electrode 101 by a vacuum evaporation method. <Lochinjektionsschicht und Lochtransportschicht>

[0102] The hole injection layer 111 injects holes from the first electrode 101 serving as an anode into the EL layer 103 and contains a material with a high hole injection property.

[0103] As a material with a high hole injection property, for example, a transition metal oxide such as a molybdenum oxide, a vanadium oxide, a ruthenium oxide, a tungsten oxide or a manganese oxide, or a phthalocyanine-based compound such as phthalocyanine (abbreviation: H2Pc) or copper(II) phthalocyanine (abbreviation: CuPc) can be used.

[0104] As a material with a high hole injection property, for example, an aromatic amine compound such as B. 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-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), 4,4'-Bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviation: DNTPD), 1,3,5-Tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B), 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) or 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1) can be used.

[0105] As a material with high hole-injection properties, 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), poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine] (abbreviation: poly-TPD), or the like can be used. Alternatively, a high-molecular compound to which an acid is added, such as poly(3,4-ethylenedioxythiophene) / poly(styrenesulfonic acid) (abbreviation: PEDOT / PSS) or polyaniline / poly(styrenesulfonic acid) (PAni / PSS), can be used.

[0106] As a material with a high hole-injection property, a composite material containing a hole-transport material and an acceptor material (electron acceptor material) can be used. In this case, the acceptor material extracts electrons from a hole-transport material, so that holes are generated in the hole-injection layer 111, and the holes are injected into the light-emitting layer 113 through the hole-transport layer 112. Note that the hole-injection layer 111 can be formed to have a single-layer structure of a composite material containing a hole-transport material and an acceptor material, or to have a multi-layer structure of a layer of a hole-transport material and a layer of an acceptor material.

[0107] The hole-transport layer 112 transports holes injected from the first electrode 101 through the hole-injection layer 111 to the light-emitting layer 113. The hole-transport layer 112 contains a hole-transport material. It is particularly preferred that the highest occupied molecular orbital (HOMO) level of the hole-transport material used for the hole-transport layer 112 be the same as or close to that of the hole-injection layer 111.

[0108] As an acceptor material used for the hole-injection layer 111, an oxide of a metal belonging to any of Groups 4 to 8 of the Periodic Table can be used. Specific examples include molybdenum oxide, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, tungsten oxide, manganese oxide, and rhenium oxide. Among these, molybdenum oxide is particularly preferred because it is stable in air, has low hygroscopicity, and is easy to handle. Alternatively, organic acceptors such as a quinodimethane derivative, a chloranil derivative, and a hexaazatriphenylene derivative can be used. Examples of those with an electron-withdrawing group (a halogen group or a cyano group) include 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT-CN) and 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviation: F6-TCNNQ).In particular, a compound in which electron-withdrawing groups are bonded to a condensed aromatic ring containing a plurality of heteroatoms, such as HAT-CN, is preferred because of its thermal stability. A [3]radialene derivative comprising an electron-withdrawing group (particularly a cyano group or a halogen group, such as a fluorine group) exhibits a very high electron-accepting property and is thus preferred. Specific examples include α,α',α''-1,2,3-cyclopropanetriylidene tris[4-cyano-2,3,5,6-tetrafluorobenzene acetonitrile], α,α',α''-1,2,3-cyclopropanetriylidene tris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzene acetonitrile] and α,α',α''-1,2,3-cyclopropanetriylidene tris[2,3,4,5,6-pentafluorobenzene acetonitrile].

[0109] The hole transport materials used for the hole injection layer 111 and the hole transport layer 112 are preferably substances with a hole mobility of greater than or equal to 10-6 cm 2 / Vs. It should be noted that other substances can also be used as long as their hole transport properties are higher than their electron transport properties.

[0110] As the hole-transporting material, materials with a high hole-transport property, such as a π-electron-rich heteroaromatic compound (e.g., a carbazole derivative, a thiophene derivative, and a furan derivative) and an aromatic amine (a compound with an aromatic amine skeleton), are preferred.

[0111] Examples of the carbazole derivative (a compound having a carbazole skeleton) include a bicarbazole derivative (e.g., a 3,3'-bicarbazole derivative) and an aromatic amine having a carbazolyl group.

[0112] Specific examples of the bicarbazole derivative (e.g., a 3,3'-bicarbazole derivative) include 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), 9,9'-bis(1,1'-biphenyl-4-yl)-3,3'-bi-9H-carbazole, 9,9'-bis(1,1'-biphenyl-3-yl)-3,3'-bi-9H-carbazole, 9-(1,1'-biphenyl-3-yl)-9'-(1,1'-biphenyl-4-yl)-9H,9'H-3,3'-bicarbazole (abbreviation: mBPCCBP), and 9-(2-naphthyl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: βNCCP).

[0113] Specific examples of the aromatic amine having a carbazolyl group include 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 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), 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-phenylcarbazol-3-yl)benzene-1,3,5-triamine (abbreviation: PCA3B), 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), PCzPCA1, PCzPCA2, PCzPCN1, 3-[N-(4-Diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA1), 3,6-Bis[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA2), 3,6-Bis[N-(4-diphenylaminophenyl)-N-(1-naphthyl)amino]-9-phenylcarbazole (abbreviation: PCzTPN2), 2-[N-(9-Phenylcarbazol-3-yl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: PCASF), N-[4-(9H-carbazol-9-yl)phenyl]-N-(4-phenyl)phenylaniline (abbreviation: YGA1BP), N,N'-bis[4-(carbazol-9-yl)phenyl]-N,N'-diphenyl-9,9-dimethylfluorene-2,7-diamine (abbreviation: YGA2F) and 4,4',4''-tris(carbazol-9-yl)triphenylamine (abbreviation: TCTA).

[0114] In addition to the above-mentioned compounds, other examples of the carbazole derivative include 3-[4-(9-phenanthryl)phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPPn), 3-[4-(1-naphthyl)phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB) and 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: CzPA).

[0115] Specific examples of the thiophene derivative (a compound having a thiophene skeleton) and the furan derivative (a compound having a furan skeleton) include a compound having a thiophene skeleton, such as: E.g. 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III) or 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II).

[0116] Specific examples of the aromatic amine 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'-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-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), N-(9,9-Dimethyl-9H-fluoren-2-yl)-N-{9,9-dimethyl-2-[N'-phenyl-N'-(9,9-dimethyl-9H-fluoren-2-yl)amino]-9H-fluoren-7-yl}phenylamine (abbreviation: DFLADFL), N-(9,9-Dimethyl-2-diphenylamino-9H-fluoren-7-yl)diphenylamine (abbreviation: DPNF), 2-[N-(4-Diphenylaminophenyl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: DPASF), 2,7-Bis[N-(4-diphenylaminophenyl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: DPA2SF), 4,4',4''-Tris[N-(1-naphthyl)-N-phenylamino]triphenylamine (abbreviation: 1'-TNATA), TDATA, m-MTDATA, N,N'-Di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), DPAB, DNTPD and DPA3B.

[0117] A high-molecular compound such as PVK, PVTPA, PTPDMA or Poly-TPD can also be used as a hole-transport material.

[0118] The hole transport material is not limited to the above examples, and one or a combination of various known materials can be used as the hole transport material for the hole injection layer 111 and the hole transport layer 112.

[0119] At the Fig. In the light-emitting device shown in Figure 1C, the light-emitting layer 113 is formed over the hole-transport layer 112 by a vacuum evaporation method. <Licht emittierende Schicht>

[0120] The light-emitting layer 113 contains a light-emitting substance.

[0121] As the light-emitting substance, the light-emitting device of one embodiment of the present invention includes a light-emitting organic compound. The light-emitting organic compound emits near-infrared light. Specifically, the maximum peak wavelength of light emitted by the light-emitting organic compound is greater than 780 nm and less than or equal to 900 nm.

[0122] For example, one of the organometallic complexes described in Embodiment 1 can be used as the light-emitting organic compound. Alternatively, one of the organometallic complexes described in the following examples can be used as the light-emitting organic compound.

[0123] The light-emitting layer 113 may contain one or more types of light-emitting substances.

[0124] The light-emitting layer 113 may contain one or more types of organic compounds (e.g., a host material and an auxiliary material) in addition to the light-emitting substance (a guest material). As one or more types of organic compounds, the hole-transport material and / or the electron-transport material described in this embodiment may be used. Alternatively, a bipolar material may be used as one or more types of organic compounds.

[0125] There is no particular limitation on the light-emitting substance that can be used for the light-emitting layer 113, and a light-emitting substance that converts the singlet excitation energy into light emission in the near-infrared light region or a light-emitting substance that converts the triplet excitation energy into light emission in the near-infrared light region can be used.

[0126] As an example of the light-emitting substance that converts singlet excitation energy into light emission, a substance that emits fluorescence (fluorescent material) can be cited. Examples include a pyrene derivative, an anthracene derivative, a triphenylene derivative, a fluorene derivative, a carbazole derivative, a dibenzothiophene derivative, a dibenzofuran derivative, a dibenzoquinoxaline derivative, a quinoxaline derivative, a pyridine derivative, a pyrimidine derivative, a phenanthrene derivative, and a naphthalene derivative.

[0127] Examples of the light-emitting substance that converts the triplet excitation energy into light emission include a substance that emits phosphorescence (phosphorescent material) and a thermally activated delayed fluorescence (TADF) material that emits thermally activated delayed fluorescence.

[0128] Examples of the phosphorescent material include an organometallic complex (particularly an iridium complex) having a 4H-triazole skeleton, a 1H-triazole skeleton, an imidazole skeleton, a pyrimidine skeleton, a pyrazine skeleton, or a pyridine skeleton, an organometallic complex (particularly an iridium complex) in which a phenylpyridine derivative having an electron-withdrawing group is a ligand, a platinum complex, and a rare earth metal complex.

[0129] The light-emitting device of one embodiment of the present invention may contain a light-emitting substance other than the light-emitting substance that emits near-infrared light. For example, the light-emitting device of one embodiment of the present invention may contain a light-emitting substance that emits visible light (red, blue, green, or the like) in addition to the light-emitting substance that emits near-infrared light.

[0130] As organic compounds (e.g., host material and auxiliary material) used in the light-emitting layer 113, one or more types of substances having a larger energy gap than the light-emitting substance may be used.

[0131] In the case where the light-emitting substance used in the light-emitting layer 113 is a fluorescent material, an organic compound used in combination with the light-emitting substance is preferably an organic compound having a high energy level in a singlet excited state and a low energy level in a triplet excited state.

[0132] Regarding a preferable combination with a light-emitting substance (a fluorescent material or a phosphorescent material), specific examples of the organic compounds are shown below, although some of them overlap with the specific examples shown above.

[0133] In the case where the light-emitting substance is a fluorescent material, examples of the organic compound that can be used in combination with the light-emitting substance include condensed polycyclic aromatic compounds such as an anthracene derivative, a tetracene derivative, a phenanthrene derivative, a pyrene derivative, a chrysene derivative, and a dibenzo[g,p]chrysene derivative.

[0134] Specific examples of the organic compound (host material) used in combination with the fluorescent material include 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), PCPN, 9,10-diphenylanthracene (abbreviation: DPAnth), N,N-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: CzA1PA), 4-(10-phenyl-9-anthryl)triphenylamine (abbreviation: DPhPA), 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: PCAPBA), N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCAPA), 6,12-Dimethoxy-5,11-diphenylchrysene, N, N, N', N', N'', N'', N''', N'''-Octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), CzPA,7-[4-(10-Phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA), 6-[3-(9,10-Diphenyl-2-anthryl)phenyl]-benzo[b]naphtho[1,2-d]furan (abbreviation: 2mBnfPPA), 9-Phenyl-10-{4-(9-phenyl-9H-fluoren-9-yl)biphenyl-4'-yl}anthracene (abbreviation: FLPPA), 9,10-Bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA), 9,10-Di(2-naphthyl)anthracene (abbreviation: DNA), 2-tert-Butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 9,9'-bianthryl (abbreviation: BANT), 9,9'-(stilbene-3,3'-diyl)diphenanthrene (abbreviation: DPNS), 9,9'-(stilbene-4,4'-diyl)diphenanthrene (abbreviation: DPNS2), 1,3,5-tri(1-pyrenyl)benzene (abbreviation: TPB3), 5,12-diphenyltetracene and 5,12-bis(biphenyl-2-yl)tetracene.

[0135] In the case where the light-emitting substance is a phosphorescent material, an organic compound having triplet excitation energy (an energy difference between a ground state and a triplet excited state) higher than that of the light-emitting substance is selected as the organic compound used in combination with the light-emitting substance.

[0136] In the case where a plurality of organic compounds (e.g., a first host material and a second host material (or an auxiliary material)) are used to form an exciplex in combination with a light-emitting substance, the plurality of organic compounds are preferably mixed with a phosphorescent material (particularly, an organometallic complex).

[0137] With such a structure, light emission can be efficiently achieved by exciplex-triplet energy transfer (ExTET), which is energy transfer from an exciplex to a light-emitting substance. Note that a combination of the various organic compounds that easily form an exciplex is preferably used, and it is particularly preferable to combine a compound that can easily accept holes (hole-transport material) and a compound that can easily accept electrons (electron-transport material). Specifically, any of the materials described in this embodiment can be used as the hole-transport material and the electron-transport material. With this structure, high efficiency, low voltage, and long lifetime of the light-emitting device can be simultaneously achieved.

[0138] In the case where the light-emitting substance is a phosphorescent material, examples of the organic compounds that can be used in combination with the light-emitting substance include an aromatic amine, a carbazole derivative, a dibenzothiophene derivative, a dibenzofuran derivative, a zinc- or aluminum-based metal complex, an oxadiazole derivative, a triazole derivative, a benzimidazole derivative, a quinoxaline derivative, a dibenzoquinoxaline derivative, a pyrimidine derivative, a triazine derivative, a pyridine derivative, a bipyridine derivative, and a phenanthroline derivative.

[0139] Among the compounds described above, specific examples of the aromatic amine (a compound having an aromatic amine skeleton), the carbazole derivative, the dibenzothiophene derivative (a thiophene derivative), and the dibenzofuran derivative (a furan derivative), which are organic compounds having a high hole-transporting property, are the same as the compounds given above as specific examples of the hole-transporting material.

[0140] Specific examples of the zinc and aluminum-based metal complexes, which are organic compounds with a high electron transport property, include 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).

[0141] A metal complex having an oxazole-based or thiazole-based ligand, such as bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO) or bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ), or the like, may alternatively be used.

[0142] Specific examples of the oxadiazole derivative, the triazole derivative, the benzimidazole derivative, the quinoxaline derivative, the dibenzoquinoxaline derivative and the phenanthroline derivative, which are organic compounds with a high electron transport property, include 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (Abbreviation: TAZ), 3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1,2,4-triazole (Abbreviation: p-EtTAZ), 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (Abbreviation: TPBI), 2-[3-(Dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (Abbreviation: mDBTBIm-II), 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (Abbreviation: BzOs), bathophenanthroline (Abbreviation: Bphen), bathocuproine (Abbreviation: BCP), 2,9-Bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBphen), 2-[3-(Dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(Dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-Carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4-(3,6-Diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(Dibenzothiophen-4-yl)phenyl]dibenzo[fh]quinoxaline (abbreviation: 7mDBTPDBq-II) and 6-[3-(Dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II).

[0143] Specific examples of a heterocyclic compound having a diazine skeleton, a heterocyclic compound having a triazine skeleton, and a heterocyclic compound having a pyridine skeleton, which are organic compounds with a high electron transport property, include 4,6-bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 9-[3-(4,6-Diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy) and 1,3,5-Tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB).

[0144] As an organic compound with a high electron transport property, a high molecular compound such as poly(2,5-pyridinediyl) (abbreviation: PPy), poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)] (abbreviation: PF-Py) or poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2'-bipyridine-6,6'-diyl)] (abbreviation: PF-BPy) can also be used.

[0145] The TADF material is a material that can upconvert a triplet excited state to a singlet excited state (i.e., reverse intersystem crossing is possible) using low thermal energy and efficiently emits light (fluorescence) from the singlet excited state. Thermally activated delayed fluorescence is efficiently obtained under the following condition: The energy difference between the triplet excitation level and the singlet excitation level is greater than or equal to 0 eV and less than or equal to 0.2 eV, preferably greater than or equal to 0 eV and less than or equal to 0.1 eV. Delayed fluorescence from the TADF material refers to light emission that has the same spectrum as normal fluorescence and a very long lifetime. The lifetime is 10 -6 seconds or longer, preferably 10 -3 seconds or longer.

[0146] Examples of the TADF material include fullerene, a derivative thereof, an acridine derivative such as proflavin, and eosin. Other examples include a metal-containing porphyrin, such as a porphyrin containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd). Examples of the metal-containing porphyrin include a protoporphyrin-tin fluoride complex (abbreviation: SnF2(Proto IX)), a mesoporphyrin-tin fluoride complex (abbreviation: SnF2(Meso IX)), a hematoporphyrin-tin fluoride complex (abbreviation: SnF2(Hemato IX)), a coproporphyrin-tetramethyl ester-tin fluoride complex (abbreviation: SnF2(Copro III-4Me)), an octaethylporphyrin-tin fluoride complex (abbreviation: SnF2(OEP)), an etioporphyrin-tin fluoride complex (abbreviation: SnF2(Etio I)) and an octaethylporphyrin-platinum chloride complex (abbreviation: PtCl2OEP).

[0147] It is also possible to prepare a heterocyclic compound with a π-electron-rich heteroaromatic ring and a π-electron-poor heteroaromatic ring, such as: B. 2-(Biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 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) or 10-phenyl-10H,10'H-spiro[acridine-9,9'-anthracene]-10'-one (abbreviation: ACRSA) should be used.It should be noted that a substance in which a π-electron-rich heteroaromatic ring is directly bonded to a π-electron-poor heteroaromatic ring is particularly preferred because both the donor property of the π-electron-rich heteroaromatic ring and the acceptor property of the π-electron-poor heteroaromatic ring are improved and the energy difference between the singlet excited state and the triplet excited state becomes small.

[0148] It should be noted that the TADF material can also be used in combination with another organic compound. In particular, the TADF material can be used in combination with the host material, the hole-transport material, and the electron-transport material described above.

[0149] Furthermore, when the above materials are used in combination with a low-molecular material or a high-molecular material, they can be used to form the light-emitting layer 113. For film formation, a known method (an evaporation method, a coating method, a printing method, or the like) can be appropriately used.

[0150] At the Fig. In the light-emitting device shown in Figure 1C, the electron transport layer 114 is formed over the light-emitting layer 113. <elektronentransportschicht>

[0151] The electron-transport layer 114 transports electrons injected from the second electrode 102 through the electron-injection layer 115 to the light-emitting layer 113. Note that the electron-transport layer 114 contains an electron-transport material. The electron-transport material used in the electron-transport layer 114 is preferably a substance with an electron mobility greater than or equal to 1 × 10 -6 cm 2 / Vs. It should be noted that other substances can also be used as long as their electron transport properties are higher than their hole transport properties.

[0152] As an electron transport material, for example, any of the following materials having a high electron transport property can be used: a metal complex having a quinoline skeleton, a metal complex having a benzoquinoline skeleton, a metal complex having an oxazole skeleton, a metal complex having a thiazole skeleton, an oxadiazole derivative, a triazole derivative, an imidazole derivative, an oxazole derivative, a thiazole derivative, a phenanthroline derivative, a quinoline derivative having a quinoline ligand, a benzoquinoline derivative, a quinoxaline derivative, a dibenzoquinoxaline derivative, a pyridine derivative, a bipyridine derivative, a pyrimidine derivative, and a π-electron-deficient heteroaromatic compound such as a nitrogen-containing heteroaromatic compound.

[0153] As specific examples of the electron transport material, the materials described above can be used.

[0154] Next, the Fig. 1C, the electron injection layer 115 is formed over the electron transport layer 114 by a vacuum evaporation method. <elektroneninjektionsschicht>

[0155] The electron injection layer 115 contains a substance with a high electron injection property. For the electron injection layer 115, an alkali metal, an alkaline earth metal, or a compound thereof, such as lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF2), or lithium oxide (LiO) can be used. x ), may also be used. A rare earth metal compound such as erbium fluoride (ErF3) may also be used. Furthermore, an electride may be used for the electron injection layer 115. Examples of the electride include a substance in which electrons are added at a high concentration to calcium oxide-alumina. Note that any of the substances described above may also be used to form the electron transport layer 114.

[0156] Alternatively, a composite material containing an electron-transport material and a donor material (electron-donor material) can be used for the electron-injection layer 115. Such a composite material has a high electron-injection property and a high electron-transport property because electrons are generated in the organic compound by the electron donor. Here, the organic compound is preferably a material that can excellently transport the generated electrons; specifically, for example, the above-described electron-transport materials (e.g., a metal complex or a heteroaromatic compound) can be used for the electron-transport layer 114. A substance that has an electron-donor property with respect to an organic compound can be used as the electron donor. Preferred examples are an alkali metal, an alkaline earth metal, and a rare earth metal.Specifically, lithium, cesium, magnesium, calcium, erbium, ytterbium, and the like can be mentioned. Furthermore, an alkali metal oxide and an alkaline earth metal oxide are preferred, and lithium oxide, calcium oxide, barium oxide, and the like can be mentioned. Alternatively, a Lewis base such as magnesium oxide can be used. As a further alternative, an organic compound such as tetrathiafulvalene (abbreviation: TTF) can be used. <ladungserzeugungsschicht>

[0157] At the Fig. In the light-emitting device shown in Fig. 1B, the charge generation layer 104 has a function of injecting electrons into the EL layer 103a and injecting holes into the EL layer 103b when a voltage is applied between the first electrode 101 (anode) and the second electrode 102 (cathode).

[0158] The charge generation layer 104 may contain a hole-transport material and an acceptor (electron-acceptor) material, or it may contain an electron-transport material and a donor material. By forming the charge generation layer 104 with such a structure, an increase in the operating voltage caused by stacking the EL layers can be suppressed.

[0159] The materials described above can be used as hole transport material, acceptor material, electron transport material and donor material.

[0160] For manufacturing the light-emitting device of this embodiment, a vacuum process such as an evaporation process or a solution process such as a spin coating process or an inkjet process can be used. When an evaporation process is used, a physical vapor deposition method (PVD method) such as a sputtering method, an ion plating method, an ion beam evaporation method, a molecular beam evaporation method, a vacuum evaporation method, a chemical vapor deposition method (CVD method), or the like can be used.Specifically, the functional layers (the hole injection layer, the hole transport layer, the light-emitting layer, the electron transport layer, and the electron injection layer) included in the EL layer and the charge generation layer can be formed by an evaporation method (e.g., a vacuum evaporation method), a coating method (e.g., a dip coating method, a die coating method, a bar coating method, a spin coating method, or a spray coating method), a printing method (e.g., an inkjet method, a screen printing (stencil printing), an offset printing (planographic printing), a flexographic printing (letter printing), a gravure printing, or a microcontact printing), or the like.

[0161] Materials of the functional layers and the charge generation layer included in the EL layer 103 are not limited to the respective materials described above. For example, a high-molecular compound (e.g., an oligomer, a dendrimer, and a polymer), a medium-molecular compound (a compound between a low-molecular compound and a high-molecular compound with a molecular weight of 400 to 4000), or an inorganic compound (e.g., a quantum dot material) can be used as the material of the functional layer. The quantum dot material can be a gelatinous quantum dot material, an alloyed quantum dot material, a core-shell quantum dot material, a core-quantum dot material, or the like. [Structural Example 1 of a Light-Emitting Device]

[0162] Fig. 2A is a plan view of a light-emitting device, and Fig. 2B and Fig. 2C are cross-sectional views along the dashed lines X1-Y1 and X2-Y2 in Fig. 2A. The light-emitting device in Fig. 2A to Fig. 2C can be used, for example, as a lighting device. The light-emitting device can have a bottom-emission structure, a top-emission structure, or a dual-emission structure.

[0163] The Fig. The light-emitting device illustrated in FIG. 2B includes a substrate 490a, a substrate 490b, a conductive layer 406, a conductive layer 416, an insulating layer 405, an organic EL device 450 (a first electrode 401, an EL layer 402, and a second electrode 403), and an adhesive layer 407. The organic EL device 450 may also be referred to as a light-emitting element, an organic EL element, a light-emitting device, or the like. As an organic light-emitting compound, a light-emitting layer in the EL layer 402 preferably includes one of the organometallic complexes described in Embodiment 1.

[0164] The organic EL device 450 includes the first electrode 401 over the substrate 490a, the EL layer 402 over the first electrode 401, and the second electrode 403 over the EL layer 402. The organic EL device 450 is sealed with the substrate 490a, the adhesive layer 407, and the substrate 490b.

[0165] End portions of the first electrode 401, the conductive layer 406, and the conductive layer 416 are covered with the insulating layer 405. The conductive layer 406 is electrically connected to the first electrode 401, and the conductive layer 416 is electrically connected to the second electrode 403. The conductive layer 406, which is covered with the insulating layer 405 with the first electrode 401 interposed therebetween, serves as an auxiliary line and is electrically connected to the first electrode 401. The auxiliary line is preferably electrically connected to the electrode of the organic EL device 450 because a voltage drop due to the resistance of the electrode can be prevented. The conductive layer 406 may be provided over the first electrode 401. Further, an auxiliary line electrically connected to the second electrode 403 may be provided, for example, over the insulating layer 405.

[0166] For the substrate 490a and the substrate 490b, glass, quartz, ceramic, sapphire, an organic resin, or the like can be used. If the substrate 490a and the substrate 490b are formed using a flexible material, the flexibility of the display device can be increased.

[0167] A light-emitting surface of the light-emitting device may be provided with a light extraction structure for increasing the light extraction efficiency, an antistatic film that prevents the adhesion of a foreign substance, a water-repellent film that suppresses the adhesion of contaminants, a hard film that suppresses generation of a scratch during use, a shock-absorbing layer, or the like.

[0168] Examples of an insulating material that can be used for the insulating layer 405 include a resin such as an acrylic resin and an epoxy resin, and an inorganic insulating material such as silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, and aluminum oxide.

[0169] As the adhesive layer 407, various curing adhesives can be used, such as a light-curing adhesive, an ultraviolet-curing adhesive, a reactive-curing adhesive, a thermosetting adhesive, and an anaerobic adhesive. Examples of these adhesives include an epoxy resin, an acrylic resin, a silicone resin, a phenolic resin, a polyimide resin, an imide resin, a polyvinyl chloride (PVC) resin, a polyvinyl butyral (PVB) resin, and an ethylene-vinyl acetate (EVA) resin. In particular, a material with low moisture permeability, such as an epoxy resin, is preferred. Alternatively, a two-component resin may be used. Alternatively, an adhesive film or the like may be used.

[0170] The Fig. The light-emitting device shown in Fig. 2C includes a barrier layer 490c, the conductive layer 406, the conductive layer 416, the insulating layer 405, the organic EL device 450, the adhesive layer 407, the barrier layer 423, and the substrate 490b.

[0171] The Fig. The barrier layer 490c shown in Figure 2C includes a substrate 420, an adhesive layer 422, and an insulating layer 424 with a high barrier property.

[0172] At the Fig. In the light-emitting device shown in Figure 2C, the organic EL device 450 is provided between the insulating layer 424 having a high barrier property and the barrier layer 423. Thus, even when resin films with relatively low water resistance or the like are used as the substrate 420 and the substrate 490b, contaminants such as water can be prevented from entering the organic EL device and shortening its lifetime.

[0173] For example, any of the following resins can be used for the substrate 420 and the substrate 490b: polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), a polyacrylonitrile resin, an acrylic resin, a polyimide resin, a polymethyl methacrylate resin, a polycarbonate (PC) resin, a polyethersulfone (PES) resin, polyamide resins (e.g., nylon and aramid), a polysiloxane resin, a cycloolefin resin, a polystyrene resin, a polyamideimide resin, a polyurethane resin, a polyvinyl chloride resin, a polyvinylidene chloride resin, a polypropylene resin, a polytetrafluoroethylene (PTFE) resin, an ABS resin, and cellulose nanofiber. Glass that is thin enough to exhibit flexibility can be used for the substrate 420 and the substrate 490b.

[0174] As the insulating layer 424 having a high barrier property, an inorganic insulating film is preferably used. For example, a silicon nitride film, a silicon oxynitride film, a silicon oxide film, a silicon nitride oxide film, an aluminum oxide film, or an aluminum nitride film can be used as the inorganic insulating film. Alternatively, a hafnium oxide film, an yttrium oxide film, a zirconium oxide film, a gallium oxide film, a tantalum oxide film, a magnesium oxide film, a lanthanum oxide film, a cerium oxide film, a neodymium oxide film, or the like can be used. Furthermore, two or more of the above-mentioned insulating films can be stacked.

[0175] The barrier layer 423 preferably includes at least a single-layer inorganic film. For example, the barrier layer 423 may have a single-layer structure of an inorganic film or a multi-layer structure of an inorganic film and an organic film. As the inorganic film, the above-described inorganic insulating film is preferably used. As the multi-layer structure, for example, a structure in which a silicon oxynitride film, a silicon oxide film, an organic film, a silicon oxide film, and a silicon nitride film are sequentially formed is given. When the protective layer has a multi-layer structure of an inorganic film and an organic film, the penetration of impurities that might penetrate into the organic EL device 450 (typically hydrogen, water, and the like) can be suitably prevented.

[0176] The insulating layer 424 with a high barrier property and the organic EL device 450 can be formed directly on the substrate 420 with flexibility. In this case, the adhesive layer 422 is not necessary. Alternatively, the insulating layer 424 and the organic EL device 450 can be formed over a rigid substrate with a release layer interposed therebetween, and then transferred to the substrate 420. For example, the insulating layer 424 and the organic EL device 450 can be transferred to the substrate 420 in the following manner: The insulating layer 424 and the organic EL device 450 are separated from the rigid substrate by applying heat, force, laser light, or the like to the release layer, and the insulating layer 424 and the organic EL device 450 are attached to the substrate 420 using the adhesive layer 422.For the separation layer, for example, a multilayer structure of inorganic films including a tungsten film and a silicon oxide film, or an organic resin film made of polyimide or the like can be used. When a rigid substrate is used, the insulating layer 424 can be formed at a high temperature compared to the case where a resin substrate or the like is used, thus the insulating layer 424 can have a high density and excellent barrier properties. [Structural Example 2 of the Light-Emitting Device]

[0177] The light-emitting device of one embodiment of the present invention may be a passive matrix device or an active matrix device. An active matrix light-emitting device is described by Fig. 3 described.

[0178] Fig. 3A is a plan view of the light-emitting device. Fig. 3B is a cross-sectional view taken along a dashed line AA' in Fig. 3A.

[0179] The light-emitting active matrix device in Fig. 3A and Fig. 3B includes a pixel section 302, a circuit section 303, a circuit section 304a, and a circuit section 304b.

[0180] Each of circuit sections 303, 304a, and 304b can serve as a scan line driver circuit (gate driver) or a signal line driver circuit (source driver). Alternatively, each of circuit sections 303, 304a, and 304b can be a circuit that electrically connects pixel section 302 to an external gate driver or an external source driver.

[0181] A connecting line 307 is provided above the first substrate 301. The connecting line 307 is electrically connected to an FPC 308, which is an external input terminal. The FPC 308 transmits a signal (e.g., a video signal, a clock signal, a start signal, or a reset signal) or a potential from the outside to the circuit section 303, the circuit section 304a, and the circuit section 304b. The FPC 308 may be provided with a printed wiring board (PWB). Fig. 3A and Fig. The structure shown in Fig. 3B may also be referred to as a light-emitting module, which includes a light-emitting device (or a light-emitting means) and an FPC.

[0182] The pixel section 302 includes a plurality of pixels, each including an organic EL device 317, a transistor 311, and a transistor 312. The transistor 312 is electrically connected to a first electrode 313 included in the organic EL device 317. The transistor 311 serves as a switching transistor. The transistor 312 serves as a current control transistor. Note that the number of transistors included in each pixel is not particularly limited and can be appropriately set as needed.

[0183] Circuit section 303 includes a plurality of transistors, such as a transistor 309 and a transistor 310. Circuit section 303 may be formed with a circuit including transistors of the same conductivity type (either n-channel transistors or p-channel transistors) or with a CMOS circuit including an n-channel transistor and a p-channel transistor. Furthermore, a driver circuit may be provided externally.

[0184] There is no particular limitation on the structure of the transistors included in the light-emitting device of this embodiment. For example, a planar transistor, a staggered transistor, or an inverted staggered transistor may be used. A top-gate transistor structure or a bottom-gate transistor structure may be used. Alternatively, gates may be provided above and below a semiconductor layer in which a channel is formed.

[0185] There is no particular limitation on the crystallinity of a semiconductor material used in the transistor, and an amorphous semiconductor or a semiconductor having crystallinity (a microcrystalline semiconductor, a polycrystalline semiconductor, a single-crystal semiconductor, or a semiconductor partially comprising crystal regions) can be used. Preferably, a semiconductor having crystallinity is used, in which case, deterioration of the transistor characteristics can be suppressed.

[0186] The semiconductor layer of the transistor preferably contains a metal oxide (also referred to as an oxide semiconductor). Alternatively, the semiconductor layer of the transistor may contain silicon. Examples of silicon include amorphous silicon and crystalline silicon (e.g., low-temperature polysilicon and single-crystal silicon).

[0187] For example, the semiconductor layer preferably contains indium, M (M is one or more species selected from gallium, aluminum, silicon, boron, yttrium, tin, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium), and zinc. Specifically, M is preferably one or more species selected from aluminum, gallium, yttrium, and tin.

[0188] For the semiconductor layer, an oxide containing indium (In), gallium (Ga) and zinc (Zn) (also called IGZO) is particularly preferably used.

[0189] In the case where the semiconductor layer is an In-M-Zn oxide, a sputtering target used to deposit the In-M-Zn oxide preferably has the atomic ratio of In higher than or equal to that of M. Examples of the atomic ratio of the metal elements in such a sputtering target are as follows: In:M:Zn = 1:1:1; In:M:Zn = 1:1:1; In:M:Zn = 1:1:1.2; In:M:Zn = 2:1:3; In:M:Zn = 3:1:2; In:M:Zn = 4:2:3; In:M:Zn = 4:2:4.1; In:M:Zn = 5:1:6; In:M:Zn = 5:1:7; In:M:Zn = 5:1:8; In:M:Zn = 6:1:6; and In:M:Zn = 5:2:5.

[0190] The transistors included in circuit sections 303, 304a, and 304b and the transistors included in pixel section 302 may have the same structure or different structures. A plurality of transistors included in circuit sections 303, 304a, and 304b may have the same structure or two or more types of structures. Similarly, a plurality of transistors included in pixel section 302 may have the same structure or two or more types of structures.

[0191] An end portion of the first electrode 313 is covered with an insulating layer 314. Note that the insulating layer 314 can be formed using an organic compound such as a negative photosensitive resin or a positive photosensitive resin (acrylic resin), or an inorganic compound such as silicon oxide, silicon oxynitride, or silicon nitride. An upper end portion or a lower end portion of the insulating layer 314 preferably has a curved surface with a curvature. In this case, favorable coverage can be achieved with a film formed over the insulating layer 314.

[0192] An EL layer 315 is provided over the first electrode 313, and a second electrode 316 is provided over the EL layer 315. The EL layer 315 includes a light-emitting layer, a hole-injection layer, a hole-transport layer, an electron-transport layer, an electron-injection layer, a charge-generation layer, and the like. In the EL layer 315, the light-emitting layer preferably includes one of the organometallic complexes described in Embodiment 1 as the light-emitting organic compound.

[0193] The plurality of transistors and the plurality of organic EL devices 317 are sealed with the first substrate 301, the second substrate 306, and the sealant 305. A space 318 enclosed by the first substrate 301, the second substrate 306, and the sealant 305 can be filled with an inert gas (e.g., nitrogen or argon) or an organic substance (including the sealant 305).

[0194] An epoxy resin or a glass frit can be used for the sealant 305. A material that allows as little moisture and oxygen permeation as possible is preferably used for the sealant 305. In the case where a glass frit is used for the sealant, the first substrate 301 and the second substrate 306 are preferably glass substrates for adhesion.

[0195] This embodiment can be combined with the other embodiments as required. (Embodiment 3)

[0196] In this embodiment, electronic devices to which the light-emitting device of one embodiment of the present invention can be applied are described by Fig. 4 described.

[0197] Fig. 4A illustrates a biometric identification device that detects a finger vein and includes a housing 911, a light source 912, a detection stand 913, and the like. By placing a finger on the detection stand 913, an image of a shape of the finger vein can be captured. The light source 912, which emits near-infrared light, is provided above the detection stand 913, and an imaging device 914 is provided below the detection stand 913. The detection stand 913 contains a material that transmits near-infrared light, and an image of near-infrared light emitted from the light source 912 and passing through the finger can be captured by the imaging device 914. Note that an optical system may be provided between the detection stand 913 and the imaging device 914.The device structure described above can be applied to a biometric identification device that detects a palm vein.

[0198] The light-emitting device of one embodiment of the present invention can be used for the light source 912. The light-emitting device of one embodiment of the present invention can be configured to have a curved shape and can emit light uniformly with respect to a target. In particular, the light-emitting device preferably emits near-infrared light with the maximum peak intensity at a wavelength of 760 nm to 900 nm. Light passing through a finger, palm, or the like is received, and its image is captured, whereby the position of the vein can be detected. This effect can be utilized for biometric identification. Furthermore, when combined with a global shutter system, the light-emitting device enables highly accurate detection even while the target is moving.

[0199] The light source 912 may include a plurality of light-emitting sections, such as in Fig. 4B. The light-emitting sections 915, 916, and 917 can emit light at different wavelengths, and furthermore, they can emit light at different times. By changing the wavelengths and angles of light, different images can be successively captured, and a plurality of images can be used for identification, achieving high security.

[0200] Fig. 4C illustrates a biometric identification device that detects a palm vein and includes a housing 921, operation buttons 922, a detection section 923, a light source 924 that emits near-infrared light, and the like. By placing a hand over the detection section 923, a shape of the palm vein can be perceived. Furthermore, a security code or the like can be input using the operation buttons. The light source 924 is provided so as to surround the detection section 923 and irradiates a target (a hand) with light. Then, light reflected from the target enters the detection section 923. The light-emitting device of one embodiment of the present invention can be used for the light source 924. An imaging device 925 is provided directly below the detection section 923 and can capture an image of the target (an entire image of the hand).Note that an optical system may be provided between the detection section 923 and the imaging device 925. The device structure described above can be applied to a biometric identification device that detects a finger vein.

[0201] Fig. 4D illustrates a non-destructive testing apparatus including a housing 931, an operation panel 932, a transport mechanism 933, a monitor 934, a detection unit 935, a light source 938 that emits near-infrared light, and the like. The light-emitting device of one embodiment of the present invention can be used for the light source 938. Inspection items 936 are transported by the transport mechanism 933 to the position directly below the detection unit 935. The inspection item 936 is irradiated with near-infrared light from the light source 938, and an image of the light passing therethrough is captured by an imaging device 937 provided in the detection unit 935. The captured image is displayed on the monitor 934. Thereafter, the inspection items 936 are transported to an exit of the housing 931, and a defective item is collected separately.Imaging using near-infrared light enables non-destructive and rapid detection of defective elements within the test element, such as defects and foreign matter.

[0202] Fig. 4E illustrates a mobile phone device including a housing 981, a display portion 982, operation buttons 983, an external connection terminal 984, a speaker 985, a microphone 986, a first camera 987, a second camera 988, and the like. The display portion 982 of the mobile phone device includes a touch sensor. The housing 981 and the display portion 982 have flexibility. All operations, such as making a call and entering text, can be performed by touching the display portion 982 with a finger, a stylus, or the like. The first camera 987 can capture a visible light image, and the second camera 988 can capture an infrared light image (a near-infrared light image). The mobile phone device or the display portion 982 in Fig. 4E may include the light emitting device of an embodiment of the present invention.

[0203] This embodiment can be combined with the other embodiments as required. [Example 1](Synthesis Example 1)

[0204] In this example, a method for synthesizing an organometallic complex of one embodiment of the present invention is described. In this example, a method for synthesizing bis{4,6-dimethyl-2-[3-(3,5-dimethylphenyl)-2-benzo[g]quinoxalinyl-κN]phenyl-κC}(2,2,6,6-tetramethyl-3,5-heptanedionato-κ 2 O,O')iridium(III) (abbreviation: [Ir(dmdpbq)2(dpm)]), which is represented by the structural formula (100) of Embodiment 1, is described. <Schritt 1: Synthese von 2,3-Bis-(3,5-dimethylphenyl)-2-benzo[g]chinoxalin (Abkürzung: Hdmdpbq)>

[0205] In Step 1, Hdmdpbq, an organic compound of one embodiment of the present invention represented by structural formula (200), was first synthesized. In a three-necked flask equipped with a reflux tube, 3.20 g of 3,3',5,5'-tetramethylbenzyl, 1.97 g of 2,3-diaminonaphthalene, and 60 ml of ethanol were added, the air in the flask was replaced with nitrogen, and then the mixture was stirred at 90°C for 7.5 hours. After a predetermined time, the solvent was distilled off. Thereafter, purification was carried out by silica gel column chromatography using toluene as the eluent to obtain the target substance (3.73 g of a yellow solid in a yield of 79%). The synthesis scheme of Step 1 is shown in (a-1).

[0206] The nuclear magnetic resonance ( 1 The analysis results of the yellow solid obtained in step 1, obtained by H-NMR spectroscopy, are shown below. Fig. 5 is the 1 H-NMR diagram. These results revealed that Hdmdpbq, represented by structural formula (200), was obtained in this example.

[0207] Below are 1 H-NMR data of the obtained substance are shown. 1 H NMR. δ (CD2Cl2): 2.28 (s, 12H), 7.01 (s, 2H), 7.16 (s, 4H), 7.56-7.58 (m, 2H), 8.11-8.13 (m, 2H), 8.74 (s, 2H). <Schritt 2: Synthese von Di-µ-chlor-tetrakis{4,6-dimethyl-2-[3-(3,5-dimethylphenyl)-2-benzo[g]chinoxalinyl-rN]phenyl-rC}diiridium(III) (Abkürzung: [Ir(dmdpbq)2Cl]2)>

[0208] Next, in Step 2, [Ir(dmdpbq)2Cl]2, which is a dinuclear complex of one embodiment of the present invention and represented by the structural formula (210), was synthesized. In a recovery flask equipped with a reflux tube, 15 ml of 2-ethoxyethanol, 5 ml of water, 1.81 g of Hdmdpbq obtained in Step 1, and 0.66 g of iridium chloride hydrate (IrCl3·H2O) (manufactured by Furuya Metal Co., Ltd.) were added, and the air in the flask was replaced with argon. Subsequently, microwave irradiation (2.45 GHz, 100 W) was performed for 2 hours to induce a reaction. After a predetermined time, the resulting residue was subjected to suction filtration with methanol and washed to obtain the target substance (1.76 g of a black solid in 81% yield). The synthesis scheme of step 2 is shown in (a-2). <Schritt 3: Synthese von [Ir(dmdpbq)2(dpm)]>

[0209] In Step 3, [Ir(dmdpbq)2(dpm)] was synthesized, which is an organometallic complex of one embodiment of the present invention and represented by the structural formula (100). In a recovery flask equipped with a reflux tube, 20 ml of 2-ethoxyethanol, 1.75 g of [Ir(dmdpbq)2Cl]2 obtained in Step 2, 0.50 g of dipivaloylmethane (abbreviation: Hdpm), and 0.95 g of sodium carbonate were added, and the air in the flask was replaced with argon. Subsequently, microwave irradiation (2.45 GHz, 100 W) was carried out for 3 hours. The obtained residue was subjected to suction filtration with methanol and then washed with water and methanol.The obtained solid was purified by silica gel column chromatography using dichloromethane as the eluent, and then recrystallized from a mixed solvent of dichloromethane and methanol to obtain the target substance (0.42 g of a dark green solid in a yield of 21%). 0.41 g of the obtained dark green solid was purified by a train sublimation method. The dark green solid was heated at 300°C under the following sublimation purification condition: the pressure was 2.7 Pa and the argon gas flow rate was 10.5 ml / min. After sublimation purification, a dark green solid was obtained in a yield of 78%. The synthesis scheme of step 3 is shown in (a-3). The nuclear magnetic resonance ( 1 The analysis results of the dark green solid obtained in step 3, obtained by H-NMR spectroscopy, are shown below. Fig. 6 is the 1 H-NMR diagram. These results revealed that [Ir(dmdpbq)2(dpm)], represented by structural formula (100), was obtained in this example.

[0210] Below are 1 H-NMR data of the obtained substance are shown. 1 H NMR. δ (CD2Cl2): 0.75 (s, 18H), 0.97 (s, 6H), 2.01 (s, 6H), 2.52 (s, 12H), 4.86 (s, 1H), 6.39 (s, 2H), 7.15 (s, 2H), 7.31 (s, 2H), 7.44-7.51 (m, 4H), 7.80 (d, 2H), 7.86 (s, 4H), 8.04 (d, 2H), 8.42 (s, 2H), 8.58 (s, 2H).

[0211] Subsequently, a UV-VIS absorption spectrum (hereinafter referred to simply as "absorption spectrum") and an emission spectrum of a dichloromethane solution of [Ir(dmdpbq)2(dpm)] were measured.

[0212] The absorption spectrum was measured at room temperature using a UV-VIS spectrophotometer (V550, manufactured by JASCO Corporation) with dichloromethane solution (0.010 mmol / L) placed in a quartz cell. The emission spectrum was measured at room temperature using a fluorescence spectrophotometer (FS920, manufactured by Hamamatsu Photonics KK), the deoxidized dichloromethane solution (0.010 mmol / L) was placed in a quartz cell under a nitrogen atmosphere, and the quartz cell was sealed.

[0213] Fig. Figure 7 shows the measurement results of the obtained absorption spectrum and emission spectrum. The horizontal axis represents the wavelength, and the vertical axes represent the absorption intensity and emission intensity. Fig. 7, a thin solid line represents the absorption spectrum, and a thick solid line represents the emission spectrum. Fig. The absorption spectrum shown in Figure 7 is a result obtained by subtracting a measured absorption spectrum of only dichloromethane placed in a quartz cell from the measured absorption spectrum of the dichloromethane solution (0.010 mmol / L) in a quartz cell.

[0214] As in Fig. As shown in Figure 7, [Ir(dmdpbq)2(dpm)], which is the organometallic complex of one embodiment of the present invention, has an emission peak at 807 nm, and near-infrared light was observed from the dichloromethane solution.

[0215] In addition, the percentage of weight loss of the obtained [Ir(dmdpbq)2(dpm)] was measured using a high-vacuum differential thermobalance (TG-DTA 2410SA, manufactured by Bruker AXS KK). The temperature was increased under a vacuum degree of 10 Pa at a temperature increase rate of 10 °C / min. As a result, as shown in Fig. 8, the percentage of weight loss of [Ir(dmdpbq)2(dpm)], which is the organometallic complex of one embodiment of the present invention, is 100%, which corresponds to a reduction rate of "-100%" in Fig. 8, which indicates a high sublimability.

[0216] As described above, [Ir(dmdpbq)2(dpm)], which is the organometallic complex of one embodiment of the present invention, could be synthesized in this example. It was found that [Ir(dmdpbq)2(dpm)] emits near-infrared light and has high sublimability.

[0217] [Ir(dmdpbq)2(dpm)] is an example of the case where X in the general formula (G1) is an unsubstituted benzene ring. When X is a benzene ring, a π-conjugated system can expand, the LUMO level becomes lower, and energetic stability is obtained; therefore, near-infrared emission is assumed to be obtained. Furthermore, [Ir(dmdpbq)2(dpm)] is an example of the case where R 1 , R 3 , R 6 and R 8 in the general formula (G1) are all methyl groups. If R 1 , R 3 , R 6 and R 8 all are methyl groups, a reduction in sublimability can be suppressed even when X is a condensed ring (benzene ring); therefore, it is considered that the organometallic complex exhibiting high sublimability and emitting near-infrared light was obtained. [Example 2]

[0218] In this example, the results of manufacturing a light-emitting device of one embodiment of the present invention are described. In particular, a structure, a manufacturing method, and properties of a light-emitting device 1 using bis{4,6-dimethyl-2-[3-(3,5-dimethylphenyl)-2-benzo[g]quinoxalinyl-κN]phenyl-κC}(2,2,6,6-tetramethyl-3,5-heptanedionato-κ 2 O,O')iridium(III) (abbreviation: [Ir(dmdpbq)2(dpm)]) (structural formula (100)), which was described in Example 1, is used in a light-emitting layer.

[0219] The light-emitting device 1 manufactured in this example is an example of a light-emitting device in which the light-emitting layer contains a light-emitting organic compound, and the maximum peak wavelength of light emitted from the light-emitting organic compound is greater than or equal to 760 nm and less than or equal to 900 nm. The light-emitting device 1 is also an example of a light-emitting device in which an organometallic complex having a metal-carbon bond is used as the light-emitting organic compound.

[0220] Fig. Figure 9A illustrates the structure of the light-emitting device 1 used in this example, and Table 1 shows specific structures. The chemical formulas of the materials used in this example are shown below. [Table 1] first electrode Hole injection layer Hole transport layer Light-emitting layer Electron transport layer Electron injection layer second electrode 801 811 812 813 814 815 803 Light-emitting device 1 ITSO (110 nm) DBT3P-II:MoOx (2:1 60 nm) BPAFLP (20 nm) * 2mDBTBPDBq-II (20 nm) NBphen (70 nm) LiF (1 nm) Al (200 nm) * 2mDBTBPDBq-II:PCBBiF:[Ir(dmdpbq)2(dpm)] (0.7:0.3:0.1 40 nm) <<Herstellung der Licht emittierenden Vorrichtung 1> >

[0221] The light-emitting device 1 described in this example has a structure in which, as shown in Fig. 9A, a first electrode 801 is formed over a substrate 800, a hole injection layer 811, a hole transport layer 812, a light emitting layer 813, an electron transport layer 814, and an electron injection layer 815 are disposed in this order over the first electrode 801, and a second electrode 803 is disposed over the electron injection layer 815.

[0222] First, the first electrode 801 was formed over the substrate 800. The electrode area was set to 4 mm 2 (2 mm × 2 mm). A glass substrate was used as the substrate 800. The first electrode 801 was formed by a sputtering method using indium tin oxide containing silicon oxide (ITSO) to a thickness of 110 nm. Note that in this example, the first electrode 801 serves as the anode.

[0223] As a pretreatment, one surface of the substrate was washed with water, baked at 200 °C for one hour, and then UV ozone treatment was performed for 370 seconds. Afterward, the substrate was transferred to a vacuum evaporation device, where the pressure was increased to approximately 10 -4 Pa, vacuum baking was performed at 170 °C for 30 minutes in a heating chamber of the vacuum evaporation device, and then the substrate was cooled for approximately 30 minutes.

[0224] Next, the hole injection layer 811 was formed over the first electrode 801. After the pressure in the vacuum evaporator was reduced to 10 -4 Pa, the hole injection layer 811 was formed such that 1,3,5-tri(dibenzothiophen-4-yl)benzene (abbreviation: DBT3P-II) and molybdenum oxide were deposited by co-evaporation in a weight ratio of DBT3P-II: molybdenum oxide = 2:1 to a thickness of 60 nm.

[0225] Next, the hole transport layer 812 was formed over the hole injection layer 811. The hole transport layer 812 was formed by evaporating 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP) to a thickness of 20 nm.

[0226] Next, the light-emitting layer 813 was formed over the hole transport layer 812. 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II) was used as the host material, N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF) was used as the auxiliary material, and [Ir(dmdpbq)2(dpm)], which is the organometallic complex of one embodiment of the present invention, was used as the guest material (phosphorescent material), and co-evaporation was carried out in a weight ratio of 2mDBTBPDBq-II:PCBBiF:[Ir(dmdpbq)2(dpm)] = 0.7:0.3:0.1. It should be noted that the thickness was set to 40 nm.

[0227] Next, the electron-transport layer 814 was formed over the light-emitting layer 813. The electron-transport layer 814 was formed in the following manner: 2mDBTBPDBq-II and 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBphen) were sequentially deposited by evaporation to a thickness of 20 nm and 70 nm, respectively.

[0228] Subsequently, the electron injection layer 815 was formed over the electron transport layer 814. Lithium fluoride (LiF) was deposited as the electron injection layer 815 by evaporation to a thickness of 1 nm.

[0229] Next, the second electrode 803 was formed over the electron injection layer 815. Aluminum was deposited as the second electrode 803 by an evaporation process to a thickness of 200 nm. Note that in this example, the second electrode 803 serves as the cathode.

[0230] Through the above steps, the light-emitting device including an EL layer 802 between the pair of electrodes was formed over the substrate 800. Note that the hole-injection layer 811, the hole-transport layer 812, the light-emitting layer 813, the electron-transport layer 814, and the electron-injection layer 815 described in the above steps are functional layers constituting the EL layer in one embodiment of the present invention. Furthermore, in all the evaporation steps of the above manufacturing method, evaporation was performed by a resistance heating method.

[0231] The light-emitting device manufactured as described above was sealed using another substrate (not shown). During sealing using the another substrate (not shown), the another substrate (not shown), to which a UV-curing sealant had been applied, was fixed to the substrate 800 in a glove box containing a nitrogen atmosphere, and the substrates were bonded together such that the sealant was applied to enclose the light-emitting device over the substrate 800. During sealing, the sealant was cured with 365 nm UV light at 6 J / cm 2 irradiated to solidify, and the sealant was heat treated at 80 °C for one hour to stabilize. <<Betriebseigenschaften der Licht emittierenden Vorrichtung 1> >

[0232] The operating characteristics of the light-emitting device 1 were measured. Note that the measurement was conducted at room temperature (in an atmosphere maintained at 25 °C).

[0233] Fig. Figure 10 shows the current density-radiance characteristics of the light-emitting device 1. Fig. Figure 11 shows the voltage-current density characteristics of the light-emitting device 1. Fig. Figure 12 shows the current density-radiant power characteristics of the light-emitting device 1. Fig. Figure 13 shows the voltage-radiance characteristics of the light-emitting device 1. Fig. Figure 14 shows the current density-external quantum efficiency characteristics of the light-emitting device 1. Note that the radiance, radiant power, and external quantum efficiency were calculated with a radiance assuming that the light-emitting device has Lambertian light distribution characteristics.

[0234] Table 2 lists the initial values ​​of main characteristics of the light-emitting device 1 at about 7.4 W / sr / m 2 . [Table 2] Voltage (V) Current (mA) Current density (mA / cm 2 ) Radiance (W / sr / m 2 ) Radiated power (mW) external quantum efficiency (%) Light-emitting device 1 6,4 2,00 51 7,4 0,09 3,2

[0235] As in Fig. 10 to Fig. 14 and Table 2, it was found that the light-emitting device 1 has advantageous properties.

[0236] Fig. 15 shows an emission spectrum when the light-emitting device 1 is supplied with current at a current density of 51 mA / cm 2 The emission spectrum was measured with a near-infrared spectroradiometer (SR-NIR, manufactured by TOPCON TECHNOHOUSE CORPORATION). As shown in Fig. As shown in Fig. 15, the emission spectrum of the light-emitting device 1 has a maximum peak at about 796 nm, which is derived from light emission of [Ir(dmdpbq)2(dpm)] contained in the light-emitting layer 813.

[0237] Furthermore, the half-width of the emission spectrum was 67 nm. The energy determined by converting this half-width into energy is approximately 0.13 eV, which is very narrow for light originating from a metal-organic complex. The light-emitting device 1 efficiently emits light from 760 nm to 900 nm (or light from 780 nm to 880 nm); therefore, it is very effective as a light source for sensor applications and the like. <<Zuverlässigkeitstest der Licht emittierenden Vorrichtung 1> >

[0238] Next, a reliability test was performed on the light-emitting device 1. Fig. 16 shows the results of the reliability test. In Fig. 16, the vertical axis represents the normalized emission intensity (%) assuming that the initial emission intensity is 100%, and the horizontal axis represents the operating time (h). In the reliability test, the light-emitting device 1 was operated at a current density of 75 mA / cm 2 operated.

[0239] The results of the reliability test show that the light-emitting device 1 has high reliability. This can be considered as an effect of using [Ir(dmdpbq)2(dpm)] (structural formula (100)), which is the organometallic complex of one embodiment of the present invention, in the light-emitting layer of the light-emitting device 1. [Example 3]

[0240] In this example, the results of manufacturing a light-emitting device according to one embodiment of the present invention will be described. The light-emitting device 2 manufactured in this example is an example of a light-emitting device in which the light-emitting layer contains a light-emitting organic compound, and the maximum peak wavelength of light emitted from the light-emitting organic compound is greater than or equal to 760 nm and less than or equal to 900 nm. The following describes the results of manufacturing the light-emitting device 2 and measuring its characteristics.

[0241] In the light-emitting device 2, bis(dibenzo[a,i]naphtho[2,1-c]phenazin-10-yl-κC 10 'κM')(2,2,6,6-tetramethyl-3,5-heptanedionato-κ 2 O,O')iridium(III) (abbreviation: [Ir(dbnphz)2(dpm)]) is used as the light-emitting organic compound in the light-emitting layer. That is, the light-emitting device 2 is an example of a light-emitting device in which an organometallic complex having a metal-carbon bond is used as the light-emitting organic compound. Note that a synthesis example of [Ir(dbnphz)2(dpm)] is described in a reference example below.

[0242] Table 3 shows specific structures of the light-emitting device 2 used in this example. It should be noted that the light-emitting device 2 has the same structure as the light-emitting device 1 ( Fig. 9A), therefore, for the manufacturing process, reference can be made to Example 2. The chemical formulas of the materials used in this example are shown below. [Table 3] first electrode Hole injection layer Hole transport layer Light-emitting layer Electron transport layer Electron injection layer second electrode 801 811 812 813 814 815 803 Light-emitting device 2 ITSO (70 nm) DBT3P-11:MoOx (2:1 120 nm) PCBBiF (20 nm) * 2mDBTBPDBq-II (20 nm) NBphen (70 nm) LiF (1 nm) Al (200 nm) * 2mDBTBPDBq-II:PCBBiF:[Ir(dbnphZ)2(dpm)] (0.7:0.3:0.1 40 nm) <<Betriebseigenschaften der Licht emittierenden Vorrichtung 2> >

[0243] The operating characteristics of the light-emitting device 2 were measured. Note that the measurement was conducted at room temperature (in an atmosphere maintained at 25 °C).

[0244] Fig. Figure 17 shows the current density-radiance characteristics of the light-emitting device 2. Fig. Figure 18 shows the voltage-current density characteristics of the light-emitting device 2. Fig. 19 shows the current density-radiant power characteristics of the light-emitting device 2. Fig. Figure 20 shows the voltage-radiance characteristics of the light-emitting device 2. Fig. Figure 21 shows the current density-external quantum efficiency characteristics of the light-emitting device 2. Note that the radiance, radiant power, and external quantum efficiency were calculated with a radiance assuming that the light-emitting device has Lambertian light distribution characteristics.

[0245] Table 4 lists the initial values ​​of main characteristics of the light-emitting device 2 at about 0.11 W / sr / m 2 . [Table 4] Voltage (V) Current (mA) Current density (mA / cm 2 ) Radiance (W / sr / m 2 ) Radiated power (mW) external quantum efficiency (%) Light-emitting device 2 5,0 0,59 15 0,11 0,0013 0,16

[0246] As in Fig. 17 to Fig. 21 and Table 4, it was found that the light-emitting device 2 has advantageous element properties.

[0247] Fig. 22 shows an emission spectrum when the light-emitting device 2 is supplied with current at a current density of 15 mA / cm 2 The emission spectrum in Fig. 22 was measured with a near-infrared spectroradiometer (SR-NIR, manufactured by TOPCON TECHNOHOUSE CORPORATION). The emission spectrum of the light-emitting device 2 has a maximum peak at approximately 870 nm, which originates from light emission of [Ir(dbnphz)2(dpm)] contained in the light-emitting layer 813.

[0248] Furthermore, the half-width of the emission spectrum was 63 nm. The energy determined by converting this half-width into energy is approximately 0.10 eV, which is very narrow for light originating from a metal-organic complex. The light-emitting device 2 efficiently emits light from 760 nm to 900 nm (or light from 780 nm to 880 nm); therefore, it is very effective as a light source for sensor applications and the like. <<Zuverlässigkeitstest der Licht emittierenden Vorrichtung 2> >

[0249] Next, a reliability test was performed on the light-emitting device 2. Fig. 23 shows the results of the reliability test. In Fig. 23, the vertical axis represents the normalized emission intensity (%) assuming that the initial emission intensity is 100%, and the horizontal axis represents the operating time (h) of the element. In the reliability test, the light-emitting device 2 was operated at a current density of 75 mA / cm 2 operated.

[0250] The results of the reliability test show that the light-emitting device 2 has high reliability. [Example 4]

[0251] This example describes the results of manufacturing a light-emitting device according to one embodiment of the present invention. Specifically, the structure, manufacturing method, and characteristics of a light-emitting device 3 using [Ir(dmdpbq)2(dpm)] described in Example 1 in a light-emitting layer are described.

[0252] The light-emitting device 3 manufactured in this example is an example of a light-emitting device in which the light-emitting layer contains a light-emitting organic compound, and the maximum peak wavelength of light emitted from the light-emitting organic compound is greater than or equal to 760 nm and less than or equal to 900 nm. The light-emitting device 3 is also an example of a light-emitting device in which an organometallic complex having a metal-carbon bond is used as the light-emitting organic compound.

[0253] Fig. 9B illustrates a structure of the light-emitting device 3 used in this example. The light-emitting device 3 used in this example is a light-emitting device having a tandem structure in which two EL layers (EL layers 802a and 802b) are provided between a pair of electrodes (the first electrode 801 and the second electrode 803), and a charge generation layer 816 is provided between the two EL layers.

[0254] Table 5 shows specific structures of the light-emitting device 3 used in this example. The chemical formulas of the materials used in this example are shown below. <<Herstellung der Licht emittierenden Vorrichtung 3> >

[0255] The light-emitting device 3 described in this example has a structure in which, as shown in Fig. 9B, the first electrode 801 is formed over the substrate 800, the EL layer 802a (a hole injection layer 811a, a hole transport layer 812a, a light emitting layer 813a, an electron transport layer 814a, and an electron injection layer 815a), the charge generation layer 816, and the EL layer 802b (a hole injection layer 811b, a hole transport layer 812b, a light emitting layer 813b, an electron transport layer 814b, and an electron injection layer 815b) are disposed in this order over the first electrode 801, and the second electrode 803 is disposed over the EL layer 802b.

[0256] First, the first electrode 801 was formed over the substrate 800. The electrode area was set to 4 mm 2 (2 mm × 2 mm). A glass substrate was used as the substrate 800. The first electrode 801 was formed in the following manner: An alloy film of silver (Ag), palladium (Pd), and copper (Cu) (an Ag-Pd-Cu (APC) film) was formed by a sputtering method to a thickness of 100 nm, and an ITSO film was formed by a sputtering method to a thickness of 10 nm. Note that in this example, the first electrode 801 serves as an anode.

[0257] As a pretreatment, one surface of the substrate was washed with water, baked at 200 °C for one hour, and then UV ozone treatment was performed for 370 seconds. Afterward, the substrate was transferred to a vacuum evaporation device, where the pressure was increased to approximately 10 -4 Pa, vacuum baking was performed at 170 °C for 30 minutes in a heating chamber of the vacuum evaporation device, and then the substrate was cooled for approximately 30 minutes.

[0258] Next, the hole injection layer 811a was formed over the first electrode 801. After the pressure in the vacuum evaporator was reduced to 10 -4 Pa, the hole injection layer 811a was formed such that DBT3P-II and molybdenum oxide were deposited by co-evaporation in a weight ratio of DBT3P-II: molybdenum oxide = 2:1 to a thickness of 10 nm.

[0259] Next, the hole transport layer 812a was formed over the hole injection layer 811a. The hole transport layer 812a was formed by evaporating PCBBiF to a thickness of 30 nm.

[0260] Next, the light-emitting layer 813a was formed over the hole-transport layer 812a. 2mDBTBPDBq-II was used as the host material, PCBBiF was used as the auxiliary material, and [Ir(dmdpbq)2(dpm)], which is the organometallic complex of one embodiment of the present invention, was used as the guest material (phosphorescent material). Co-evaporation was performed in a weight ratio of 2mDBTBPDBq-II:PCBBiF:[Ir(dmdpbq)2(dpm)] = 0.7:0.3:0.1. Note that the thickness was set to 40 nm.

[0261] Next, the electron-transport layer 814a was formed over the light-emitting layer 813a. The electron-transport layer 814a was formed in the following manner: 2mDBTBPDBq-II and NBphen were sequentially deposited by evaporation to a thickness of 20 nm and 90 nm, respectively.

[0262] Subsequently, the electron injection layer 815a was formed over the electron transport layer 814a. Lithium oxide (Li2O) was deposited as the electron injection layer 815a by evaporation to a thickness of 0.1 nm.

[0263] Next, the charge generation layer 816 was formed over the electron injection layer 815a. The charge generation layer 816 was formed by evaporating copper(II) phthalocyanine (CuPc) to a thickness of 2 nm.

[0264] Next, the hole injection layer 811b was formed over the charge generation layer 816. The hole injection layer 811b was formed by co-evaporating DBT3P-II and molybdenum oxide in a weight ratio of DBT3P-II:molybdenum oxide = 2:1 to a thickness of 10 nm.

[0265] Next, the hole transport layer 812b was formed over the hole injection layer 811b. The hole transport layer 812b was formed by evaporating PCBBiF to a thickness of 60 nm.

[0266] Next, the light-emitting layer 813b was formed over the hole-transport layer 812b. 2mDBTBPDBq-II was used as the host material, PCBBiF was used as the auxiliary material, and [Ir(dmdpbq)2(dpm)], which is the organometallic complex of one embodiment of the present invention, was used as the guest material (phosphorescent material). Co-evaporation was performed in a weight ratio of 2mDBTBPDBq-II:PCBBiF:[Ir(dmdpbq)2(dpm)] = 0.7:0.3:0.1. Note that the thickness was set to 40 nm.

[0267] Next, the electron-transport layer 814b was formed over the light-emitting layer 813b. The electron-transport layer 814b was formed in the following manner: 2mDBTBPDBq-II and NBphen were sequentially deposited by evaporation to a thickness of 20 nm and 65 nm, respectively.

[0268] Subsequently, the electron injection layer 815b was formed over the electron transport layer 814b. Lithium fluoride (LiF) was deposited as the electron injection layer 815b by evaporation to a thickness of 1 nm.

[0269] Next, the second electrode 803 was formed over the electron injection layer 815b. As the second electrode 803, silver (Ag) and magnesium (Mg) were co-evaporated in a volume ratio of Ag:Mg = 10:1 to a thickness of 20 nm. Note that in this example, the second electrode 803 serves as the cathode.

[0270] Next, a buffer layer 804 was formed over the second electrode 803. The buffer layer 804 was formed by evaporating DBT3P-II to a thickness of 110 nm.

[0271] Through the above steps, the light-emitting device 3 was formed over the substrate 800. Furthermore, in all evaporation steps of the above manufacturing method, evaporation was performed by a resistance heating method.

[0272] The light-emitting device 3 was sealed using another substrate (not shown). The sealing method is the same as that for the light-emitting device 1, and therefore, for the sealing method, reference can be made to Example 2.

[0273] Note that a microcavity structure is used for the light-emitting device 3. The light-emitting device 3 was fabricated such that the optical path length between the pair of reflective electrodes (the APC film and the Ag:Mg film) is approximately one wave with respect to the maximum peak wavelength of light emitted from the guest material. <<Betriebseigenschaften der Licht emittierenden Vorrichtung 3> >

[0274] The operating characteristics of the light-emitting device 3 were measured. Note that the measurement was conducted at room temperature (in an atmosphere maintained at 25 °C).

[0275] Fig. 24 shows the current density-radiance characteristics of the light-emitting device 3. Fig. Figure 25 shows the voltage-current density characteristics of the light-emitting device 3. Fig. 26 shows the current density-radiant power characteristics of the light-emitting device 3. Fig. Figure 27 shows the voltage-radiance characteristics of the light-emitting device 3. Fig. Figure 28 shows the current density-external quantum efficiency characteristics of the light-emitting device 3. Note that the radiance, radiant power, and external quantum efficiency were calculated with a radiance assuming that the light-emitting device has Lambertian light distribution characteristics.

[0276] Table 6 lists the initial values ​​of main characteristics of the light-emitting device 3 at about 6.8 W / sr / m 2 . [Table 6] Voltage (V) Current (mA) Current density (mA / cm 2 ) Radiance (W / sr / m 2 ) Radiated power (mW) external quantum efficiency (%) Light-emitting device 3 8,8 0,42 11 6,8 0,09 13

[0277] As in Fig. 24 to Fig. As shown in Figure 28 and Table 6, it was found that the light-emitting device 3 exhibited advantageous properties. Since the light-emitting device 3 has a tandem structure, the results with a high peak EL intensity and a high external quantum efficiency were obtained.

[0278] Fig. 29 shows an emission spectrum when the light-emitting device 3 is supplied with current at a current density of 10 mA / cm 2 The emission spectrum was measured with a near-infrared spectroradiometer (SR-NIR, manufactured by TOPCON TECHNOHOUSE CORPORATION). As shown in Fig. 29, the emission spectrum of the light-emitting device 3 has a maximum peak at about 799 nm, which is derived from light emission of [Ir(dmdpbq)2(dpm)] contained in the light-emitting layer 813a and the light-emitting layer 813b.

[0279] By using the microcavity structure, the emission spectrum narrowed, and the half-width was 32 nm. The light-emitting device 3 efficiently emits light from 760 nm to 900 nm (or light from 780 nm to 880 nm); therefore, it is very effective as a light source for sensor applications and the like. <<Zuverlässigkeitstest der Licht emittierenden Vorrichtung 3> >

[0280] Next, a reliability test was performed on the light-emitting device 3. Fig. 30 shows the results of the reliability test. In Fig. 30, the vertical axis represents the normalized emission intensity (%) assuming that the initial emission intensity is 100%, and the horizontal axis represents the operating time (h). In the reliability test, the light-emitting device 3 was operated at a current density of 75 mA / cm 2 operated

[0281] The results of the reliability test show that the light-emitting device 3 has high reliability. This can be considered as an effect of using [Ir(dmdpbq)2(dpm)] (structural formula (100)), which is the organometallic complex of one embodiment of the present invention, in the light-emitting layer of the light-emitting device 3. <<Betrachtungswinkeleigenschaften der Licht emittierenden Vorrichtung 3> >

[0282] Next, the viewing angle characteristics of the EL spectra of the light-emitting device 3 were investigated.

[0283] First, the EL spectra in the forward direction and the EL spectra in oblique directions of the light-emitting element were measured. Specifically, emission spectra were measured at a total of 17 points, i.e., at every 10° from -80° to 80°, assuming that a direction perpendicular to a light-emitting surface of the light-emitting device was 3 0°. A multi-channel spectrometer (PMA-12, manufactured by Hamamatsu Photonics KK) was used for the measurement. From the measurement results, the EL spectra and the photon intensity ratio of the light-emitting element at each angle were obtained.

[0284] Fig. 31 shows the EL spectra of the light-emitting device 3 from 0° to 60°.

[0285] Fig. 32 shows the photon intensity (normalized photon intensity) of the light-emitting device 3 at each angle with respect to the photon intensity at the front. Fig. 32 also shows Lambertian properties.

[0286] As in Fig. 31 and Fig. As shown in Figure 32, it was found that the light-emitting device 3 exhibits a large viewing angle dependence and emits intense light in the forward direction. This is because the use of the microcavity structure reduces light emission in oblique directions while enhancing light emission in the forward direction. Consequently, viewing angle characteristics with intense light emission in the forward direction are suitable for use as a light source in sensor applications such as a vein sensor. (Reference example)

[0287] A method for synthesizing bis(dibenzo[a,i]naphtho[2,1-c]phenazin-10-yl-κC 10 ,κN 11 )(2,2,6,6-tetramethyl-3,5-heptanedionato-κ 2 O,O')iridium(III) (abbreviation: [Ir(dbnphz)2(dpm)]), used in Example 3 above, is specifically described. The structure of [Ir(dbnphz)2(dpm)] is shown below. <Schritt 1: Synthese von Dibenzo[a, / ]naphtho[2,1-c]phenazin (Abkürzung: Hdbnphz)>

[0288] First, 1.0 g (4.0 mmol) of chrysene-5,6-dione, 0.67 g (4.3 mmol) of 2,3-diaminonaphthalene, and 20 mL of ethanol were added to a reaction vessel, and the mixture was heated and refluxed for 5 hours. After a predetermined time, the resulting mixture was subjected to suction filtration, and the solid was washed with ethanol. This solid was dissolved in heated toluene, and the solution was subjected to suction filtration through a filter medium in which Celite, alumina, and Celite were arranged in this order. The obtained filtrate was concentrated, and recrystallized from a mixed solvent of toluene and ethanol was performed to obtain the target substance (1.1 g in a yield of 74%). The synthesis scheme of step 1 is shown in (b-1). <Schritt 2: Synthese von [Ir(dbnphz)2(dpm)]>

[0289] Next, 1.1 g (2.9 mmol) of Hdbnphz obtained in Step 1, 0.39 g (1.3 mmol) of iridium chloride hydrate, and 30 ml of dimethylformamide (DMF) were added to a reaction vessel, the air in the vessel was replaced with nitrogen, and the mixture was heated and stirred at 160 °C for 7.5 hours. After a predetermined time, 0.55 g (5.2 mmol) of sodium carbonate and 0.72 g (3.9 mmol) of dipivaloylmethane were added, and the mixture was heated and stirred at 140 °C for 14 hours. Then, this mixture was subjected to suction filtration, and the obtained solid was washed with water and ethanol.

[0290] This solid was then purified by silica gel column chromatography using dichloromethane as the eluent, and the resulting fraction was concentrated to obtain a solid. This solid was washed with warmed toluene to obtain 133 mg of the target substance.

[0291] Next, the resulting filtrate was concentrated and purified by silica gel column chromatography using toluene as the eluent. Then, the solid obtained by concentrating the resulting fraction was recrystallized from a mixed solvent of toluene and ethanol to obtain the target substance (80 mg) (total yield of 213 mg, 14%). The synthesis scheme of step 2 is shown in formula (b-2).

[0292] The protons ( 1 H) of the black solid obtained in step 2 were measured by nuclear magnetic resonance spectroscopy (NMR). The obtained values ​​are shown below. These measurement results revealed that [Ir(dbnphz)2(dpm)]) was obtained.

[0293] 1 H-NMR δ (CDCI3): 0.52 (s, 18H), 5.04 (s, 1H), 6.80 (d, 2H), 6.97 (t, 2H), 7.48 (d, 2H), 7.59 (t, 2H), 7.74 (t, 2H), 7.88 (d, 2H), 7.98 (t, 2H), 8.06 (d, 2H), 8.10 (d, 2H), 8.26 (d, 4H), 8.64 (d, 2H), 9.13 (s, 2H), 9.19 (s, 2H), 11.21 (d, 2H). Erläuterung der Bezugszeichen

[0294] 101: first electrode, 102: second electrode, 103: EL layer, 103a: EL layer, 103b: EL layer, 104: charge generation layer, 111: hole injection layer, 112: hole transport layer, 113: light-emitting layer, 114: electron transport layer, 115: electron injection layer, 301: first substrate, 302: pixel portion, 303: circuit portion, 304a: circuit portion, 304b: circuit portion, 305: sealant, 306: second substrate, 307: lead, 308: FPC, 309: transistor, 310: transistor, 311: transistor, 312: transistor, 313: first electrode, 314: insulating layer, 315: EL layer, 316: second electrode, 317: organic EL device, 318: space, 401: first electrode, 402: EL layer, 403: second electrode, 405: insulating layer, 406: conductive layer, 407: adhesive layer, 416: conductive layer, 420: substrate, 422: adhesive layer, 423: barrier layer, 424: insulating layer, 450: organic EL device, 490a: substrate, 490b: substrate, 490c: barrier layer, 800: substrate,801: first electrode, 802: EL layer, 802a: EL layer, 802b: EL layer, 803: second electrode, 804: buffer layer, 811: hole injection layer, 811a: hole injection layer, 811b: hole injection layer, 812: hole transport layer, 812a: hole transport layer, 812b: hole transport layer, 813: light-emitting layer, 813a: light-emitting layer, 813b: light-emitting layer, 814: electron transport layer, 814a: electron transport layer, 814b: electron transport layer, 815: electron injection layer, 815a: electron injection layer, 815b: electron injection layer, 816: charge generation layer, 911: package, 912: light source, 913: Detection stand, 914: Imaging device, 915: Light-emitting section, 916: Light-emitting section, 917: Light-emitting section, 921: Housing, 922: Control knob, 923: Detection section, 924: Light source, 925: Imaging device, 931: Housing, 932: Control panel, 933: Transport mechanism, 934: Monitor,935: Detection unit, 936: Test element, 937: Imaging device, 938: Light source, 981: Housing, 982: Display section, 983: Control button, 984: External connection port, 985: Speaker, 986: Microphone, 987: Camera, 988: Camera,< / ladungserzeugungsschicht> < / elektroneninjektionsschicht> < / elektronentransportschicht>

Claims

[1] Organometallic complex represented by the general formula (G1), where: R 1 to R 11 each independently represents hydrogen or an alkyl group having 1 to 6 carbon atoms, at least two of R 1 to R 4 each represent an alkyl group with 1 to 6 carbon atoms, at least two of R 5 to R 9 each represent an alkyl group with 1 to 6 carbon atoms, X represents a substituted or unsubstituted benzene ring or naphthalene ring, n is 2 or 3, and L represents a monoanionic ligand. [2] The organometallic complex according to claim 1, wherein the organometallic complex is represented by the general formula (G2), wherein: R 1 , R 3 , R 6 and R 8each independently represents an alkyl group having 1 to 6 carbon atoms. [3] The organometallic complex according to claim 1 or 2, wherein the maximum peak wavelength of light emitted from the organometallic complex is greater than or equal to 760 nm and less than or equal to 900 nm. [4] The organometallic complex according to claim 1 or 2, wherein the organometallic complex is a light-emitting material. [5] Light-emitting device comprising a light-emitting layer, wherein the light-emitting layer comprises the light-emitting material according to claim 4, and wherein the light-emitting device has a function of emitting light whose maximum peak wavelength is greater than or equal to 760 nm and less than or equal to 900 nm.

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