Light-emitting device, electronic appliance, light-emitting apparatus, and illumination apparatus

Abstract

To provide an organic compound that easily exhibits thermally active delay fluorescence (TADF).SOLUTION: An organic compound is represented by the following general formula (G1). In the general formula (G1), each of R1 to R8 independently represents any one of hydrogen, an alkyl group with 1 to 6 carbons, a cycloalkyl group with 3 to 7 carbons, and a substituted or a non-substituted diarylamino group. Note that at least one of R1 to R8 is the substituted or a non-substituted diarylamino group. In addition, α represents a substituted or a non-substituted phenylene group and n is an integer of 0 to 4. Moreover, A represents a substituted or a non-substituted benzofuro-pyrimidine skeleton or benzothienopyrimidine skeleton.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] One aspect of the present invention relates to an organic compound, a light-emitting element, a light-emitting device, a display module, a lighting module, a display device, a light-emitting device, an electronic device, a lighting device, and an electronic device. Note that one aspect of the present invention is not limited to the above technical field. The technical field of one aspect of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. Alternatively, one aspect of the present invention relates to a process, a machine, a manufacture, or a composition of matter. Therefore, more specifically, as the technical field of one aspect of the present invention disclosed in this specification, semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, lighting devices, power storage devices, storage devices, imaging devices, driving methods thereof, or manufacturing methods thereof can be given as an example.

Background Art

[0002] The practical application of light-emitting devices (organic EL devices) using electroluminescence (EL) using organic compounds has been progressing. The basic configuration of these light-emitting devices is such that an organic compound layer (EL layer) containing a light-emitting material is sandwiched between a pair of electrodes. By applying a voltage to this element to inject carriers and utilizing the recombination energy of the carriers, light emission from the light-emitting material can be obtained.

[0003] Since such a light-emitting device is self-luminous, when used as a pixel of a display, it has advantages such as higher visibility and no need for a backlight compared to liquid crystals, and is suitable as a flat panel display element. In addition, a display using such a light-emitting device can be manufactured to be thin and lightweight, which is also a great advantage. Furthermore, it is also characterized by a very fast response speed.

[0004] In addition, since these light-emitting devices can form a light-emitting layer continuously in two dimensions, planar light emission can be obtained. This is a characteristic that is difficult to achieve with point light sources typified by incandescent bulbs and LEDs, or line light sources typified by fluorescent lamps. Therefore, it also has high utility value as a planar light source that can be applied to lighting and the like.

[0005] As described above, displays and lighting devices using such light-emitting devices are highly suitable for various electronic devices, and research and development are being advanced to obtain light-emitting devices with better characteristics (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] In one aspect of the present invention, an object is to provide a novel organic compound. Or, in one aspect of the present invention, an object is to provide an organic compound that easily exhibits delayed fluorescence and thermally activated delayed fluorescence (TADF). Or, in one aspect of the present invention, an object is to provide an organic compound that exhibits TADF emission. Or, in one aspect of the present invention, an object is to provide an organic compound capable of providing a light-emitting element with good luminous efficiency.

[0008] Or, in one aspect of the present invention, an object is to provide a light-emitting device with good luminous efficiency. Or, in one aspect of the present invention, an object is to provide a light-emitting device that exhibits TADF emission.

[0009] Or, in one aspect of the present invention, an object is to provide a light-emitting device, an electronic device, a display device, and an electronic device each having low power consumption.

[0010] Note that the description of these effects does not preclude the existence of other effects. Note that one aspect of the present invention does not necessarily have all of these effects. Note that other effects will become apparent from the description in the specification, drawings, claims, etc., and it is possible to extract these other effects from the description in the specification, drawings, claims, etc.

[0011] The present invention only needs to solve any one of the above problems.

Means for Solving the Problems

[0012] One aspect of the present invention is an organic compound represented by the following general formula (G1).

[0013]

Chemical formula

[0014] However, in the above general formula (G1), R 1 to R 8 are each independently any one of hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, and a substituted or unsubstituted diarylamino group. Note that at least one of R 1 to R 8 is a substituted or unsubstituted diarylamino group. Also, α represents a substituted or unsubstituted phenylene group, n is an integer from 0 to 4. Also, A represents a substituted or unsubstituted benzofuropyrimidine skeleton or a benzothienopyrimidine skeleton.

[0015] Alternatively, another aspect of the present invention is an organic compound in the above configuration, wherein A is a group represented by the following general formula (g1).

[0016]

Chemical formula

[0017] However, in the above general formula (g1), R 11 to R16 One of them is a linking group, and the rest are each independently any one of hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, and an aryl group having 6 to 13 carbon atoms that forms a substituted or unsubstituted ring. Also, Q represents an oxygen atom or a sulfur atom.

[0018] Alternatively, another aspect of the present invention is an organic compound represented by the following general formula (G2).

[0019]

Chemical formula

[0020] However, in the above general formula (G2), R 1 to R 8 are each independently any one of hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, and a substituted or unsubstituted diarylamino group. Note that at least one of R 1 to R 8 is a substituted or unsubstituted diarylamino group. Also, α represents a substituted or unsubstituted phenylene group, and n is an integer from 0 to 4. Also, R 11 to R 15 are each independently any one of hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, and an aryl group having 6 to 13 carbon atoms that forms a substituted or unsubstituted ring. Also, Q represents an oxygen atom or a sulfur atom.

[0021] Alternatively, another aspect of the present invention is an organic compound in the above configuration, wherein the substituted or unsubstituted diarylamino group is a group represented by the following general formula (g2).

[0022]

Chemical formula

[0023] However, in the above general formula (g2), Ar 1 and Ar 2Each independently represents an aryl group having 6 to 13 carbon atoms that forms a substituted or unsubstituted ring.

[0024] Alternatively, another aspect of the present invention is, in the above configuration, R 3 and R 6 is an organic compound in which one or both of them are groups represented by the general formula (g2).

[0025] Alternatively, another aspect of the present invention is an organic compound represented by the following general formula (G3).

[0026]

Chemical formula

[0027] However, in the general formula (G3), Ar 3 to Ar 6 each independently represents any of aryl groups having 6 to 13 carbon atoms that form a substituted or unsubstituted ring. Also, R 1 , R 2 , R 4 , R 5 , R 7 and R 8 each independently represents any one of hydrogen, an alkyl group having 1 to 6 carbon atoms, and a cycloalkyl group having 3 to 7 carbon atoms. Also, α represents a substituted or unsubstituted phenylene group, and n is an integer from 0 to 4. Also, R 11 to R 15 each independently represents any one of hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, and an aryl group having 6 to 13 carbon atoms that forms a substituted or unsubstituted ring. Also, Q represents an oxygen atom or a sulfur atom.

[0028] Alternatively, another aspect of the present invention is an organic compound represented by the following general formula (G4).

[0029]

Chemical formula

[0030] However, in the above general formula (G4), Ar 3 to Ar 6 is each independently any of aryl groups having 6 to 13 carbon atoms that form a substituted or unsubstituted ring. Further, α represents a substituted or unsubstituted phenylene group, and n is an integer from 0 to 4. Also, R 13 is any of hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, and an aryl group having 6 to 13 carbon atoms that form a substituted or unsubstituted ring. Also, Q represents an oxygen atom or a sulfur atom.

[0031] Or, another aspect of the present invention is an organic compound represented by the following general formula (G5).

[0032]

Chemical formula

[0033] However, in the above general formula (G5), Ar 3 to Ar 6 is each independently any of aryl groups having 6 to 13 carbon atoms that form a substituted or unsubstituted ring. Also, R 13 is any of hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, and an aryl group having 6 to 13 carbon atoms that form a substituted or unsubstituted ring. Also, Q represents an oxygen atom or a sulfur atom.

[0034] Or, another aspect of the present invention is an organic compound represented by the following structural formula (100).

[0035]

Chemical formula

[0036] Or, another aspect of the present invention is an organic compound represented by the following structural formula (101).

[0037]

Chemical formula

[0038] Alternatively, another aspect of the present invention is an organic compound represented by the following structural formula (102).

[0039] [Chemical formula]

[0040] Alternatively, another aspect of the present invention is an organic compound in which the difference between the lowest singlet excitation level and the lowest triplet excitation level is 0.2 eV or less in the above configuration.

[0041] Alternatively, another aspect of the present invention is an organic compound in which the difference between the lowest singlet excitation level and the lowest triplet excitation level is 0.1 eV or less in the above configuration.

[0042] Alternatively, another aspect of the present invention is an organic compound in which Q is an oxygen atom in the above configuration.

[0043] Alternatively, another aspect of the present invention is an electronic device having a first electrode, a second electrode, and an organic layer sandwiched between the first electrode and the second electrode, wherein the organic layer contains an organic compound having the above configuration.

[0044] Alternatively, another aspect of the present invention is a light-emitting device having a first electrode, a second electrode, and an organic layer sandwiched between the first electrode and the second electrode, wherein the organic layer contains an organic compound having the above configuration.

[0045] Alternatively, another aspect of the present invention is a light-emitting device in which the organic layer has a light-emitting layer and the organic compound is contained in the light-emitting layer in the above configuration.

[0046] Alternatively, another aspect of the present invention is a light-emitting device in which the light emission from the organic layer is delayed fluorescence in the above configuration.

[0047] Alternatively, another aspect of the present invention is a light-emitting device in the above configuration, wherein the transient lifetime of the delayed fluorescence is 100 nanoseconds or more and 10 milliseconds or less.

[0048] Alternatively, another aspect of the present invention is a light-emitting device in the above configuration, wherein the light-emitting layer further contains a fluorescent material.

[0049] Alternatively, another aspect of the present invention is a light-emitting device in the above configuration, wherein the light-emitting layer further contains a phosphorescent material.

[0050] Alternatively, another aspect of the present invention is an electronic device having the light-emitting device described in any of the above and a sensor, an operation button, a speaker, or a microphone.

[0051] Alternatively, another aspect of the present invention is a light-emitting device having the light-emitting device described in any of the above and a transistor or a substrate.

[0052] Alternatively, another aspect of the present invention is a lighting device having the light-emitting device described in any of the above and a housing.

[0053] Note that the light-emitting device in this specification includes an image display device using a light-emitting device. In addition, a module in which a connector, for example, an anisotropic conductive film or a TCP (Tape Carrier Package), is attached to the light-emitting device, a module in which a printed wiring board is provided at the tip of the TCP, or a module in which an IC (integrated circuit) is directly mounted on the light-emitting device by the COG (Chip On Glass) method may also be included in the light-emitting device. Furthermore, lighting fixtures and the like may have a light-emitting device.

Advantages of the Invention

[0054] In one aspect of the present invention, a novel organic compound can be provided. Or, in one aspect of the present invention, an organic compound that is likely to exhibit thermally activated delayed fluorescence (TADF) can be provided. Or, in one aspect of the present invention, an organic compound that exhibits TADF emission can be provided. Or, in one aspect of the present invention, an organic compound that can provide a light-emitting device with good luminous efficiency can be provided.

[0055] Or, in one aspect of the present invention, a light-emitting device with good luminous efficiency can be provided. Or, in one aspect of the present invention, a light-emitting device that exhibits TADF emission can be provided.

[0056] Or, in one aspect of the present invention, a light-emitting device, an electronic device, a display device, and an electronic device with low power consumption can be provided, respectively.

[0057] Note that the description of these effects does not prevent the existence of other effects. Note that one aspect of the present invention does not necessarily have to have all of these effects. Note that other effects will naturally become clear from the descriptions in the specification, drawings, claims, etc., and it is possible to extract these other effects from the descriptions in the specification, drawings, claims, etc.

Brief Description of Drawings

[0058]

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Figure 56

Mode for Carrying Out the Invention

[0059] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it will be easily understood by those skilled in the art that the form and details can be variously changed without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description of the embodiments shown below.

[0060] (Embodiment 1) Since thermally activated delayed fluorescence (TADF) materials can convert triplet excitation energy into light emission, they have attracted attention as high-efficiency light-emitting materials to replace phosphorescent materials in current-excited light-emitting devices, and the development of TADF materials capable of achieving high luminous efficiency is desired.

[0061] Unlike ordinary organic compounds, organic compounds exhibiting TADF properties are known to have a very small difference (ΔE ST ) between the lowest singlet excitation level (S1 level) and the lowest triplet excitation level (T1 level). In order to realize such a state, it is necessary that the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) are distributed in the molecule so as to be spatially separated.

[0062] The ΔE ST of the organic compound of one aspect of the present invention is 0.2 eV or less, preferably 0.1 eV or less, which is very small, and the organic compound exhibits TADF emission efficiently. The organic compound of one aspect of the present invention is represented by the following general formula (G1).

[0063]

Chemical formula

[0064] In the above general formula (G1), R 1 to R 8 are each independently any one of hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, and a substituted or unsubstituted diarylamino group. Note that R1 up to R 8 is at least 1 a diarylamino group which may be substituted or unsubstituted.

[0065] Also, α represents a substituted or unsubstituted phenylene group, and n is an integer from 0 to 4. Note that n is preferably 0 or 1 for the T1 level to be high. In the phosphorescent light-emitting device or exciton-trapping type fluorescent element, when used as an energy donor of the green light-emitting material, since a higher T1 level is required, from this viewpoint, n is preferably 0. Also, from the viewpoint of making the energy of ΔE ST smaller, n is preferably 1.

[0066] A represents a substituted or unsubstituted benzofuropyrimidine skeleton or a substituted or unsubstituted benzothienopyrimidine skeleton. The benzofuropyrimidine skeleton can also be represented by the following general formula (g1). In the following general formula (g1), Q represents an oxygen atom or a sulfur atom.

[0067]

Chemical formula

[0068] In the above general formula (g1), R 11 to R 16 one of them is a bond, which binds to α or the nitrogen atom of the carbazolyl group in the above general formula (G1). Also, the rest are each independently any of hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, and an aryl group having 6 to 13 carbon atoms that forms a substituted or unsubstituted ring.

[0069] In the above general formula (g1), it is preferable that the bond is R 16 for ease of synthesis and good stability. That is, the organic compound of one embodiment of the present invention is preferably an organic compound represented by the following general formula (G2).

[0070] [Chemistry]

[0071] In the above general formula (G2), R 1 to R 8 are each independently one of hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, and a substituted or unsubstituted diarylamino group. Note that at least one of R 1 to R 8 is a substituted or unsubstituted diarylamino group.

[0072] Also, α represents a substituted or unsubstituted phenylene group, and n is an integer from 0 to 4.

[0073] Also, R 11 to R 15 are each independently one of hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, and an aryl group having 6 to 13 carbon atoms that forms a substituted or unsubstituted ring. Also, Q represents an oxygen atom or a sulfur atom.

[0074] Note that in the above general formulas (G1) and (G2), at least one of R 1 to R 8 which is a substituted or unsubstituted diarylamino group is preferably a group represented by the following general formula (g2).

[0075] [Chemistry]

[0076] In this specification, Ar 1 and Ar 2 each independently represent an aryl group having 6 to 13 carbon atoms that forms a substituted or unsubstituted ring.

[0077] In the above general formulas (G1) and (G2), R 1 to R 8It is preferable that one or two of them are groups represented by the above general formula (g2), R 3 and R 6 It is preferable that one or both of them are groups represented by the above general formula (g2). In the above general formulas (G1) and (G2), R 1 to R 8 It is preferable that two of them are groups represented by the above general formula (g2). That is, the organic compound of one aspect of the present invention is preferably an organic compound represented by the following general formula (G3).

[0078] [Chemical formula]

[0079] In the above general formula (G3), Ar 3 to Ar 6 are each independently any of aryl groups having 6 to 13 carbon atoms forming a substituted or unsubstituted ring.

[0080] Also, R 1 , R 2 , R 4 , R 5 , R 7 and R 8 are each independently any one of hydrogen, an alkyl group having 1 to 6 carbon atoms, and a cycloalkyl group having 3 to 7 carbon atoms.

[0081] Also, α represents a substituted or unsubstituted phenylene group, and n is an integer from 0 to 4.

[0082] Also, R 11 to R 15 are each independently any one of hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, and an aryl group having 6 to 13 carbon atoms forming a substituted or unsubstituted ring. Also, Q represents an oxygen atom or a sulfur atom.

[0083] In the above general formula (G3), R 1 , R 2 , R 4 , R5 , R 7 , R 8 , R 11 , R 12 , R 14 and R 15 and R being hydrogen is preferable because the T1 level is high and synthesis is easy. That is, the organic compound of one aspect of the present invention is preferably an organic compound represented by the following general formula (G4).

[0084] [Chemical formula]

[0085] However, in the above general formula (G4), Ar 3 to Ar 6 are each independently any of aryl groups having 6 to 13 carbon atoms forming a substituted or unsubstituted ring.

[0086] Further, α represents a substituted or unsubstituted phenylene group, and n is an integer of 0 to 4.

[0087] Also, R 13 is any of hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, and an aryl group having 6 to 13 carbon atoms forming a substituted or unsubstituted ring. Also, Q represents an oxygen atom or a sulfur atom.

[0088] In the organic compounds represented by the above general formulas (G1) to (G4), α is preferably an unsubstituted phenylene group.

[0089] Also, in the organic compounds represented by the above general formulas (G1) to (G4), n being 1 or 0 is preferable because the T1 level is high, and more preferably, n is 0. That is, the organic compound of one aspect of the present invention is preferably an organic compound represented by the following general formula (G5).

[0090] [Chemical formula]

[0091] However, in the above general formula (G5), Ar 3 to Ar 6 is each independently any of aryl groups having 6 to 13 carbon atoms that form a substituted or unsubstituted ring.

[0092] Also, R 13 is any of hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, and an aryl group having 6 to 13 carbon atoms that form a substituted or unsubstituted ring. Further, Q represents an oxygen atom or a sulfur atom.

[0093] In the present specification, specifically, examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a tert-butyl group, a pentyl group, and a hexyl group. Specific examples of the cycloalkyl group having 3 to 7 carbon atoms include a cyclopropyl group and a cyclohexyl group. Specific examples of the aryl group having 6 to 13 carbon atoms that form a ring include a phenyl group, a biphenyl group, a naphthyl group, and a fluorenyl group.

[0094] Also, in the present specification, when it is described as "substituted or unsubstituted", if it has a substituent, the substituent is assumed to refer to an alkyl group having 1 to 6 carbon atoms and a cycloalkyl group having 3 to 7 carbon atoms.

[0095] The organic compound of one embodiment of the present invention having the above configuration has a small ΔE ST and is an organic compound that easily obtains thermally activated delayed fluorescence (TADF) emission because reverse intersystem crossing easily occurs, and emits light with good efficiency. Further, a light-emitting device using the organic compound can be a light-emitting device that emits light with very good efficiency. When measuring the transient electroluminescence (EL) of a light-emitting device using the organic compound of one embodiment of the present invention, a delayed fluorescence component is observed, and its transient lifetime is 100 nanoseconds or more and 10 milliseconds or less, preferably 1 microsecond or more and 10 microseconds or less.

[0096] Specific examples of the organic compound having the above structure are shown below.

[0097]

Chem.

[0098]

Chem.

[0099]

Chem.

[0100]

Chem.

[0101]

Chem.

[0102]

Chem.

[0103]

Chem.

[0104]

Chem.

[0105] Next, a method for synthesizing the organic compound represented by the general formula (G1) will be described. As shown in the following synthesis scheme, the compound represented by the general formula (G1) can be obtained by coupling an organic boron compound of a carbazole derivative, or boric acid (Compound 1) and a halide or triflate-substituted product (Compound 2) of a benzofuropyrimidine derivative or a benzothienopyrimidine derivative by the Suzuki-Miyaura reaction. In the following synthesis scheme, R 1 to R 8 are each independently any one of hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, and a substituted or unsubstituted diarylamino group. Note that at least one of R 1 to R 8 is a substituted or unsubstituted diarylamino group. Further, α represents a substituted or unsubstituted phenylene group, n is an integer from 0 to 4. Also, A represents a substituted or unsubstituted benzofuropyrimidine skeleton or a substituted or unsubstituted benzothienopyrimidine skeleton.

[0106]

Chemical formula

[0107] In the above synthesis scheme, X 12 represents a halogen such as chlorine, bromine, iodine or a triflate group. When X 12 is a halogen, chlorine, bromine and iodine are particularly preferred.

[0108] Also, R 50 and R 51 each independently represent hydrogen or an alkyl group having 1 to 6 carbon atoms, and R 50 and R 51 may be bonded to each other to form a ring.

[0109] Examples of the palladium catalyst that can be used in the reaction represented by the above synthetic scheme include palladium(II) acetate, tetrakis(triphenylphosphine)palladium(0), bis(triphenylphosphine)palladium(II) dichloride, and the like.

[0110] Examples of the ligand of the above palladium catalyst include di(1-adamantyl)-n-butylphosphine, tri(o-tolyl)phosphine, triphenylphosphine, tricyclohexylphosphine, and the like.

[0111] Examples of the base that can be used in the reaction represented by the above synthetic scheme include organic bases such as sodium tert-butoxide, and inorganic bases such as potassium carbonate and sodium carbonate.

[0112] Examples of the solvent that can be used in the reaction represented by the above synthetic scheme include a mixed solvent of toluene and water, a mixed solvent of toluene and an alcohol such as ethanol and water, a mixed solvent of xylene and water, a mixed solvent of xylene and an alcohol such as ethanol and water, a mixed solvent of benzene and water, a mixed solvent of benzene and an alcohol such as ethanol and water, a mixed solvent of an ether such as ethylene glycol dimethyl ether and water, and a mixed solvent of an ether such as ethylene glycol dimethyl ether and an alcohol such as ethanol. However, the solvents that can be used are not limited to these. Further, a mixed solvent of toluene and water, or a mixed solvent of toluene, ethanol, and water, a mixed solvent of an ether such as ethylene glycol dimethyl ether and water, and a mixed solvent of an ether such as ethylene glycol dimethyl ether and an alcohol such as ethanol are more preferred.

[0113] As the coupling reaction that can be used in the above synthesis scheme, instead of the Suzuki-Miyaura coupling reaction using the organic boron compound or boronic acid represented by Compound 1, a cross-coupling reaction using an organoaluminum, organozirconium, organozinc, organotin compound, etc. may be used. Further, in the reaction shown in the above synthesis scheme, an organic boron compound or boronic acid of a benzofuropyrimidine derivative or benzothienopyrimidine derivative and a halide or triflate-substituted product of a carbazole derivative may be coupled by the Suzuki-Miyaura reaction.

[0114] In addition, the compound represented by the general formula (G1) can also be synthesized by the synthesis method as shown in the examples.

[0115] (Embodiment 2) In this embodiment, a light-emitting device according to one aspect of the present invention will be described.

[0116] FIG. 1A shows a diagram representing a light-emitting device according to one aspect of the present invention. The light-emitting device according to one aspect of the present invention has a first electrode 101, a second electrode 102, and an EL layer 103. Further, the EL layer 103 has the organic compound shown in Embodiment 1.

[0117] The EL layer 103 has a light-emitting layer 113, and the light-emitting layer 113 contains a light-emitting material. A hole injection layer 111 and a hole transport layer 112 are provided between the light-emitting layer 113 and the first electrode 101. Since the organic compound described in Embodiment 1 emits light efficiently by TADF, it is preferably used as a light-emitting material.

[0118] Further, the light-emitting layer 113 may be configured to contain a host material together with a light-emitting material. The host material is an organic compound having carrier transport properties. Also, not only one kind of host material but a plurality of kinds may be included. In that case, it is preferable that a plurality of organic compounds are an organic compound having electron transport properties and an organic compound having hole transport properties, because it becomes possible to adjust the carrier balance in the light-emitting layer 113. Also, a plurality of organic compounds may both be organic compounds having electron transport properties (or hole transport properties), but it is also possible to adjust the carrier transport properties in the light-emitting layer 113 by the difference in their carrier transport properties. By appropriately adjusting the carrier balance, it becomes possible to provide a light-emitting device with good lifetime and a light-emitting device with good luminous efficiency. Also, a configuration may be adopted in which an exciplex is formed between a plurality of organic compounds that are host materials or between a host material and a light-emitting material. By forming an exciplex having an appropriate emission wavelength, effective energy transfer to the light-emitting material can be realized, and it becomes possible to provide a light-emitting device having high efficiency and good lifetime.

[0119] Also, when an exciplex is formed between the host material and the light-emitting material to emit light, a device with higher efficiency (for example, an external quantum efficiency of 7% or more) than a normal fluorescent element may be obtained. Also in this case, delayed fluorescence is observed from the light-emitting device.

[0120] Note that the organic compound according to one embodiment of the present invention has bipolarity and can also be suitably used as a host material for the light-emitting layer. Since the organic compound according to one embodiment of the present invention has TADF properties, it becomes possible to convert triplet excitation energy into singlet excitation energy. By transferring the converted singlet excitation energy to a fluorescent light-emitting material for energy transfer to emit light, triplet excitation energy can be converted into light emission, so that a fluorescent light-emitting device with very good luminous efficiency can be obtained (so-called exciton trapping type fluorescent element). Also, since the fluorescent light-emitting material that emits light is stable, it is easy to make the light-emitting device a light-emitting device with good lifetime.

[0121] In addition, in FIG. 1A, the EL layer 103 is shown to include a light-emitting layer 113, a hole injection layer 111, a hole transport layer 112, an electron transport layer 114, and an electron injection layer 115. However, the configuration of the light-emitting device is not limited to these. It is not necessary to form any of these layers, or the device may have layers with other functions.

[0122] Subsequently, the detailed structure and material examples of the above-described light-emitting device will be described. The light-emitting device according to one aspect of the present invention has an EL layer 103 composed of a plurality of layers between a pair of electrodes, i.e., the first electrode 101 and the second electrode 102 as described above, and any part of the EL layer 103 contains the organic compound disclosed in Embodiment 1.

[0123] The first electrode 101 is preferably formed using a metal, alloy, conductive compound, or a mixture thereof having a large work function (specifically, 4.0 eV or more). Specifically, for example, indium tin oxide (ITO), indium tin oxide containing silicon or silicon oxide, indium zinc oxide, indium tungsten oxide (IWZO) containing tungsten oxide and zinc oxide, etc. may be mentioned. These conductive metal oxide films are usually formed by a sputtering method, but may also be produced by applying a sol-gel method or the like. As an example of the production method, indium zinc oxide can be formed by a sputtering method using a target in which 1 to 20 wt% of zinc oxide is added to indium oxide. Also, indium tungsten oxide (IWZO) containing tungsten oxide and zinc oxide can be formed by a sputtering method using a target containing 0.5 to 5 wt% of tungsten oxide and 0.1 to 1 wt% of zinc oxide with respect to indium oxide. In addition, gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), or nitrides of metal materials (for example, titanium nitride), etc. may be mentioned. Graphene can also be used. By using the composite material described later in the layer in contact with the first electrode 101 in the EL layer 103, the electrode material can be selected regardless of the work function.

[0124] The EL layer 103 preferably has a laminated structure, but the laminated structure is not particularly limited, and various layer structures such as a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, a carrier blocking layer, an exciton blocking layer, and a charge generation layer can be applied. In the present embodiment, as an example, as shown in FIG. 1A, in addition to the hole injection layer 111, the hole transport layer 112, and the light emitting layer 113, a configuration having an electron transport layer 114 and an electron injection layer 115, and as shown in FIG. 1B, in addition to the hole injection layer 111, the hole transport layer 112, and the light emitting layer 113, two types of configurations having an electron transport layer 114 and a charge generation layer 116 will be described. The materials constituting each layer are specifically shown below.

[0125] The positive hole injection layer 111 is a layer containing a substance having acceptor properties. As the substance having acceptor properties, either an organic compound or an inorganic compound can be used.

[0126] As the substance having acceptor properties, a compound having an electron-withdrawing group (halogen group or cyano group) can be used, and examples thereof 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), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviation: F6-TCNNQ), 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyrene-2-ylidene) malononitrile, and the like. In particular, a compound in which an electron-withdrawing group is bonded to a condensed aromatic ring having a plurality of heteroatoms like HAT-CN is thermally stable and preferable. Further, a [3]radialene derivative having an electron-withdrawing group (particularly a halogen group such as a fluoro group or a cyano group) is preferable because of its very high electron-accepting property. Specifically, α,α’,α’’-1,2,3-cyclopropanetriylidene tris[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α’,α’’-1,2,3-cyclopropanetriylidene tris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], α,α’,α’’-1,2,3-cyclopropanetriylidene tris[2,3,4,5,6-pentafluorobenzeneacetonitrile], and the like can be mentioned. Since the organic compound having acceptor properties is easy to vapor-deposit and easy to form a film, it is a material that is easy to use.

[0127] As the substance having acceptor properties, in addition to the organic compounds described above, molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, manganese oxide, etc. can be used.

[0128] In addition, a hole injection layer 111 can also be formed by phthalocyanine-based complex compounds such as phthalocyanine (abbreviation: H2Pc), copper phthalocyanine (CuPc), aromatic amine compounds such as 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), N,N'-bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviation: DNTPD), or polymers such as poly(3,4-ethylenedioxythiophene) / poly(styrenesulfonic acid) (PEDOT / PSS). A substance having acceptor properties can extract electrons from an adjacent hole transport layer (or hole transport material) by applying an electric field.

[0129] Also, as the hole injection layer 111, a composite material in which a material having hole transport properties contains the above-mentioned substance having acceptor properties can be used. By using a composite material in which a material having hole transport properties contains a substance having acceptor properties, a material for forming an electrode can be selected regardless of the work function. That is, as the first electrode 101, not only a material having a large work function but also a material having a small work function can be used.

[0130] As the material having hole transport properties used in the composite material, various organic compounds such as aromatic amine compounds, carbazole derivatives, aromatic hydrocarbons, and polymer compounds (oligomers, dendrimers, polymers, etc.) can be used. Note that the material having hole transport properties used in the composite material is preferably a substance having a hole mobility of 1×10 -6 cm 2 / Vs or more. Hereinafter, organic compounds that can be used as the material having hole transport properties in the composite material will be specifically listed.

[0131] Examples of aromatic amine compounds that can be used in composite materials include N,N'-di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), N,N'-bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviation: DNTPD), 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B), and the like. Specific examples of carbazole derivatives include 3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2), 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1), 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB), 9-[4-(N-carbazolyl)]phenyl-10-phenylanthracene (abbreviation: CzPA), 1,4-bis[4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene, and the like can be used.Examples of the aromatic hydrocarbon include 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 2-tert-butyl-9,10-di(1-naphthyl)anthracene, 9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA), 2-tert-butyl-9,10-bis(4-phenylphenyl)anthracene (abbreviation: t-BuDBA), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA), 9,10-diphenylanthracene (abbreviation: DPAnth), 2-tert-butylanthracene (abbreviation: t-BuAnth), 9,10-bis(4-methyl-1-naphthyl)anthracene (abbreviation: DMNA), 2-tert-butyl-9,10-bis[2-(1-naphthyl)phenyl]anthracene, 9,10-bis[2-(1-naphthyl)phenyl]anthracene, 2,3,6,7-tetramethyl-9,10-di(1-naphthyl)anthracene, 2,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene, 9,9'-bianthryl, 10,10'-diphenyl-9,9'-bianthryl, 10,10'-bis(2-phenylphenyl)-9,9'-bianthryl, 10,10'-bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9'-bianthryl, anthracene, tetracene, rubrene, perylene, 2,5,8,11-tetra(tert-butyl)perylene, etc. In addition, pentacene, coronene, etc. can also be used. It may have a vinyl skeleton. Examples of the aromatic hydrocarbon having a vinyl group include 4,4'-bis(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi), 9,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene (abbreviation: DPVPA), etc.

[0132] In addition, high molecular compounds such as poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphenylamine) (abbreviation: PVTPA), poly[N-(4-{N’-[4-(4-diphenylamino)phenyl]phenyl-N’-phenylamino}phenyl)methacrylamide] (abbreviation: PTPDMA), poly[N,N’-bis(4-butylphenyl)-N,N’-bis(phenyl)benzidine] (abbreviation: Poly-TPD) can also be used.

[0133] As the material having hole transporting property used in the composite material, it is more preferable to have any of a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton. In particular, it may be an aromatic amine having a substituent containing a dibenzofuran ring or a dibenzothiophene ring, an aromatic monoamine having a naphthalene ring, or an aromatic monoamine in which a 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group. Incidentally, when these second organic compounds are substances having an N,N-bis(4-biphenyl)amino group, it is preferable because a light-emitting device with good lifetime can be fabricated. Specific examples of the second organic compound as described above include N-(4-biphenyl)-6,N-diphenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BnfABP), N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf), 4,4'-bis(6-phenylbenzo[b]naphtho[1,2-d]furan-8-yl)-4''-phenyltriphenylamine (abbreviation: BnfBB1BP), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-6-amine (abbreviation: BBABnf(6)), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf(8)), N,N-bis(4-biphenyl)benzo[b]naphtho[2,3-d]furan-4-amine (abbreviation: BBABnf(II)(4)), N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP), N-[4-(dibenzothiophene-4-yl)phenyl]-N-phenyl-4-biphenylamine (abbreviation: ThBA1BP), 4-(2-naphthyl)-4',4''-diphenyltriphenylamine (abbreviation: BBAβNB), 4-[4-(2-naphthyl)phenyl]-4',4''-diphenyltriphenylamine (abbreviation: BBAβNBi), 4,4'-diphenyl-4''-(6;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβNB), 4,4'-diphenyl-4''-(7;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβNB-03), 4,4’-Diphenyl-4’’-(7-phenyl)naphthalen-2-yltriphenylamine (abbreviation: BBAPβNB-03), 4,4’-diphenyl-4’’-(6;2’-binaphthalen-2-yl)triphenylamine (abbreviation: BBA(βN2)B), 4,4’-diphenyl-4’’-(7;2’-binaphthalen-2-yl)triphenylamine (abbreviation: BBA(βN2)B-03), 4,4’-diphenyl-4’’-(4;2’-binaphthalen-1-yl)triphenylamine (abbreviation: BBAβNαNB), 4,4’-diphenyl-4’’-(5;2’-binaphthalen-1-yl)triphenylamine (abbreviation: BBAβNαNB-02), 4-(4-biphenylyl)-4’-(2-naphthyl)-4’’-phenyltriphenylamine (abbreviation: TPBiAβNB), 4-(3-biphenylyl)-4’-[4-(2-naphthyl)phenyl]-4’’-phenyltriphenylamine (abbreviation: mTPBiAβNBi), 4-(4-biphenylyl)-4’-[4-(2-naphthyl)phenyl]-4’’-phenyltriphenylamine (abbreviation: TPBiAβNBi), 4-phenyl-4’-(1-naphthyl)triphenylamine (abbreviation: αNBA1BP), 4,4’-bis(1-naphthyl)triphenylamine (abbreviation: αNBB1BP), 4,4’-diphenyl-4’’-[4’-(carbazol-9-yl)biphenyl-4-yl]triphenylamine (abbreviation: YGTBi1BP), 4’-[4-(3-phenyl-9H-carbazol-9-yl)phenyl]tris(1,1’-biphenyl-4-yl)amine (abbreviation: YGTBi1BP-02), 4-diphenyl-4’-(2-naphthyl)-4’’-{9-(4-biphenylyl)carbazole)}triphenylamine (abbreviation: YGTBiβNB), N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-[4-(1-naphthyl)phenyl]-9,9’-spirobi[9H-fluorene]-2-amine (abbreviation: PCBNBSF), N,N-bis(4-biphenylyl)-9,9’-spirobi[9H-fluorene]-2-amine (abbreviation: BBASF), N,N-bis(1,1’-biphenyl-4-yl)-9,9’-spirobi[9H-fluorene]-4-amine (abbreviation: BBASF(4)), N-(1,1’-biphenyl-2-yl)-N-(9,(9-Dimethyl-9H-fluoren-2-yl)-9,9'-spirobi[9H-fluorene]-4-amine (abbreviation: oFBiSF), N-(4-biphenyl)-N-(dibenzofuran-4-yl)-9,9-dimethyl-9H-fluorene-2-amine (abbreviation: FrBiF), N-[4-(1-naphthyl)phenyl]-N-[3-(6-phenyldibenzofuran-4-yl)phenyl]-1-naphthylamine (abbreviation: mPDBfBNBN), 4-phenyl-4'-(9-phenylfluorene-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenylfluorene-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-phenyl-4'-[4-(9-phenylfluorene-9-yl)phenyl]triphenylamine (abbreviation: BPAFLBi), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]spiro-9,9'-bifluorene-2-amine (abbreviation: PCBASF), N-(1,1'-biphenyl-4-yl)-9,9-dimethyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9H-fluorene-2-amine (abbreviation: PCBBiF), N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi[9H-fluorene]-4-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi[9H-fluorene]-3-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi[9H-fluorene]-2-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi[9H-fluorene]-1-amine, etc. can be mentioned.,

[0134] Note that the material having hole transporting property used in the composite material preferably has a relatively deep HOMO level of -5.7 eV or more and -5.4 eV or less. When the material having hole transporting property used in the composite material has a relatively deep HOMO level, injection of holes into the hole transport layer 112 becomes easy, and it also becomes easy to obtain a light-emitting device with good lifetime.

[0135] In addition, by further mixing a fluoride of an alkali metal or an alkaline earth metal into the above composite material (preferably, the atomic ratio of fluorine atoms in the layer is 20% or more), the refractive index of the layer can be decreased. Also by this, a layer with a low refractive index can be formed inside the EL layer 103, and the external quantum efficiency of the light-emitting device can be improved.

[0136] By forming the hole injection layer 111, the injectability of holes becomes good, and a light-emitting device with a small driving voltage can be obtained.

[0137] The hole transport layer 112 is formed by including a material having hole transporting property. As the material having hole transporting property, 1×10 -6 cm 2It is preferably having a hole mobility of / Vs or more. Examples of the material having the above hole transporting property include 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4'-bis[N-(spiro-9,9'-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), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluorene-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]spiro-9,9'-bifluorene-2-amine (abbreviation: PCBASF) and other compounds having an aromatic amine skeleton, 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP) and other compounds having a carbazole skeleton, 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,Compounds having a thiophene skeleton such as 8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), etc., and compounds having a furan skeleton such as 4,4’,4’’-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II), 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II), etc. Among the above-mentioned compounds, compounds having an aromatic amine skeleton and compounds having a carbazole skeleton are preferable because they have good reliability, high hole transportability, and contribute to reducing the driving voltage. In addition, the substances listed as hole-transporting materials used in the composite material of the hole injection layer 111 can also be suitably used as the materials constituting the hole transport layer 112. Since the organic compound described in Embodiment 1 has high hole transportability, it can be very suitably used as the material constituting the hole transport layer 112. Further, since the organic compound described in Embodiment 1 has high hole transportability, even if the hole transport layer 112 is formed with a thick film of 100 nm or more, it is possible to provide a light-emitting device having good device characteristics with a small increase in the driving voltage. By thickening the hole transport layer 112, the optical path length between the electrodes can be easily adjusted, so that it becomes easy to appropriately configure the microcavity structure.,

[0138] The light-emitting layer 113 has a light-emitting substance and a host material. Note that the light-emitting layer 113 may simultaneously contain other materials. Also, it may be a laminate of two layers with different compositions.

[0139] The light-emitting substance may be a fluorescent light-emitting substance, a phosphorescent light-emitting substance, a substance showing thermally activated delayed fluorescence (TADF), or other light-emitting substances, but the organic compound of one aspect of the present invention can be preferably used. The organic compound of one aspect of the present invention is a substance that efficiently shows TADF.

[0140] In the light-emitting layer 113, examples of materials that can be used as fluorescent light-emitting substances include 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine (abbreviation: PAP2BPy), 5,6-bis[4'-(10-phenyl-9-anthryl)biphenyl-4-yl]-2,2'-bipyridine (abbreviation: PAPP2BPy), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn), N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole-3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetra(tert-butyl)perylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), N,N''-(2-tert-butylanthracene-9,10-diyl-di-4,1-phenylene)bis[N,N',N'-triphenyl-1,4-phenylenediamine] (abbreviation: DPABPA), N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazole-3-amine (abbreviation: 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), N,N,N',N',N'',N'',N''',N''' - octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), coumarin 30, N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazole-3-amine (abbreviation: 2PCAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazole-3-amine (abbreviation: 2PCABPhA), N-(9,10-diphenyl-2-anthryl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPABPhA), 9,10-bis(1,1'-biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracen-2-amine (abbreviation: 2YGABPhA), N,N,9-triphenylanthracen-9-amine (abbreviation: DPhAPhA), Coumarin 545T, N,N'-diphenylquinacridone, (abbreviation: DPQd), Rubrene, 5,12-bis(1,1'-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyran-4-ylidene)propanedinitrile (abbreviation: DCM1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM2), N,N,N',N'-tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviation: p-mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB), 2-(2,6-bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDCM), 2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJTM), N,N'-(pyrene-1,6-diyl)bis[(6,N-diphenylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-03), 3,10-bis[N-(9-phenyl-9H-carbazol-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10PCA2Nbf(IV)-02), 3,10-bis[N-(dibenzofuran-3-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10FrA2Nbf(IV)-02), etc. are mentioned. In particular, condensed aromatic diamine compounds typified by pyrene diamine compounds such as 1,6FLPAPrn, 1,6mMemFLPAPrn, and 1,6BnfAPrn-03 are preferable because they have high hole trapping properties and are excellent in luminous efficiency and reliability. In addition, other fluorescent substances can also be used.,

[0141] When a phosphorescent material is used as the luminescent material in the light-emitting layer 113, examples of the materials that can be used include organometallic iridium complexes having a 4H-triazole skeleton such as tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN2]phenyl-κC}iridium(III) (abbreviation: [Ir(mpptz-dmp)3]), tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Mptz)3]), tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(iPrptz-3b)3]), organometallic iridium complexes having a 1H-triazole skeleton such as tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(Mptz1-mp)3]), tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Prptz1-Me)3]), organometallic iridium complexes having an imidazole skeleton such as fac-tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviation: [Ir(iPrpmi)3]), tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: [Ir(dmpimpt-Me)3]), bis[2-(4’,6’-difluorophenyl)pyridinato-N,C 2’ iridium(III) tetrakis(1-pyrazolyl)borate (abbreviation: FIr6), bis[2-(4’,6’-difluorophenyl)pyridinato-N,C 2’ iridium(III) picolinate (abbreviation: FIrpic), bis{2-[3’,5’-bis(trifluoromethyl)phenyl]pyridinato-N,C 2’}iridium(III) picolinate (abbreviation: [Ir(CF3ppy)2(pic)]), bis[2-(4’,6’-difluorophenyl)pyridinato-N,C 2’Examples include organometallic iridium complexes having a phenylpyridine derivative having an electron-withdrawing group such as iridium(III) acetylacetonate (abbreviation: FIracac) as a ligand. These are compounds that exhibit blue phosphorescent emission and have a peak in the emission wavelength from 440 nm to 520 nm.

[0142] Also, tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)3]), tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)3]), (acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)2(acac)]), (acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)2(acac)]), (acetylacetonato)bis[6-(2-norbornyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(nbppm)2(acac)]), (acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(mpmppm)2(acac)]), (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm)2(acac)]) and other organometallic iridium complexes having a pyrimidine skeleton, (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-Me)2(acac)]), (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-iPr)2(acac)]) and other organometallic iridium complexes having a pyrazine skeleton, tris(2-phenylpyridinato-N,C 2’ )iridium(III) (abbreviation: [Ir(ppy)3]), bis(2-phenylpyridinato-N,C 2’Iridium(III) acetylacetonate (abbreviation: [Ir(ppy)2(acac)]), bis(benzo[h]quinolinato)iridium(III) acetylacetonate (abbreviation: [Ir(bzq)2(acac)]), tris(benzo[h]quinolinato)iridium(III) (abbreviation: [Ir(bzq)3]), tris(2-phenylquinolinato-N,C 2’ ) iridium(III) (abbreviation: [Ir(pq)3]), bis(2-phenylquinolinato-N,C 2’ ) iridium(III) acetylacetonate (abbreviation: [Ir(pq)2(acac)]), [2-d3-methyl-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(5-d3-methyl-2-pyridyl-κN2)phenyl-κ]iridium(III) (abbreviation: [Ir(5mppy-d3)2(mbfpypy-d3)]), [2-d3-methyl-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: [Ir(ppy)2(mbfpypy-d3)]), in addition to organometallic iridium complexes having a pyridine skeleton, and rare earth metal complexes such as tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviation: [Tb(acac)3(Phen)]). These are mainly compounds that exhibit green phosphorescent emission and have a peak in the emission wavelength range of 500 nm to 600 nm. In addition, organometallic iridium complexes having a pyrimidine skeleton are particularly preferred because of their outstanding reliability and luminescence efficiency.

[0143] In addition, organometallic iridium complexes having a pyrimidine skeleton such as (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III) (abbreviation: [Ir(5mdppm)2(dibm)]), bis[4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(5mdppm)2(dpm)]), bis[4,6-di(naphthalen-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(d1npm)2(dpm)]), organometallic iridium complexes having a pyrazine skeleton such as (acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: [Ir(tppr)2(acac)]), bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: [Ir(tppr)2(dpm)]), (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: [Ir(Fdpq)2(acac)]), other than organometallic iridium complexes having a pyridine skeleton such as tris(1-phenylisoquinolinato-N,C 2’ )iridium(III) (abbreviation: [Ir(piq)3]), bis(1-phenylisoquinolinato-N,C 2’ )iridium(III) acetylacetonate (abbreviation: [Ir(piq)2(acac)]), platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum(II) (abbreviation: PtOEP), rare earth metal complexes such as tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III) (abbreviation: [Eu(DBM)3(Phen)]), tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III) (abbreviation: [Eu(TTA)3(Phen)]), etc. These are compounds that exhibit red phosphorescent emission and have an emission peak at 600 nm to 700 nm. In addition, organometallic iridium complexes having a pyrazine skeleton can obtain red emission with good chromaticity.

[0144] In addition to the phosphorescent materials described above, known phosphorescent materials may be selected and used.

[0145] As the material showing TADF (TADF material), fullerenes and their derivatives, acridine and its derivatives, eosin derivatives, etc. can be used. Also, metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd), etc. can be mentioned. Examples of the metal-containing porphyrin include protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF2(OEP)), etioporphyrin-tin fluoride complex (SnF2(Etio I)), octaethylporphyrin-platinum chloride complex (PtCl2OEP), etc. shown by the following structural formulas. Note that the organic compound of one aspect of the present invention is also a TADF material.

[0146]

Chemical formula

[0147] Also, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 9-(4,6-diphenyl-1,3,5-triazin-2-yl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCzTzn), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 2-[4-(10H-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-dihydroacridin)phenyl]sulfone (abbreviation: DMAC-DPS), 10-phenyl-10H,10'H-spiro[acridine-9,9'-anthracene]-10'-one (abbreviation: ACRSA), etc., heterocyclic compounds having one or both of a π-electron-excessive heterocyclic aromatic ring and a π-electron-deficient heterocyclic aromatic ring can also be used. Since the heterocyclic compound has a π-electron-excessive heterocyclic aromatic ring and a π-electron-deficient heterocyclic aromatic ring, it has both high electron transport properties and hole transport properties, which is preferable. Among them, among the skeletons having a π-electron-deficient heterocyclic aromatic ring, a pyridine skeleton, a diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), and a triazine skeleton are preferable because they are stable and have good reliability. In particular, a benzofuropyrimidine skeleton, a benzothienopyrimidine skeleton, a benzofuropyrazine skeleton, and a benzothienopyrazine skeleton are preferable because they have high acceptor properties and good reliability. Also, among the skeletons having a π-electron-excessive heterocyclic aromatic ring, an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, a thiophene skeleton, and a pyrrole skeleton are stable and have good reliability, so it is preferable to have at least one of these skeletons.As the furan skeleton, a dibenzofuran skeleton is preferable, and as the thiophene skeleton, a dibenzothiophene skeleton is preferable. As the pyrrole skeleton, an indole skeleton, a carbazole skeleton, an indolocarbazole skeleton, a bicarbasole skeleton, and a 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole skeleton are particularly preferable. In addition, a substance in which a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded has both the electron-donating property of the π-electron-rich heteroaromatic ring and the electron-accepting property of the π-electron-deficient heteroaromatic ring enhanced, and the energy difference between the S1 level and the T1 level becomes small. Therefore, it is particularly preferable because TADF can be efficiently obtained. Instead of the π-electron-deficient heteroaromatic ring, an aromatic ring to which an electron-withdrawing group such as a cyano group is bonded may be used. Further, as the π-electron-rich skeleton, an aromatic amine skeleton, a phenazine skeleton, etc. can be used. Further, as the π-electron-deficient skeleton, a xanthene skeleton, a thioxanthene dioxide skeleton, an oxadiazole skeleton, a triazole skeleton, an imidazole skeleton, an anthraquinone skeleton, a boron-containing skeleton such as phenylborane and borantrene, an aromatic ring and a heteroaromatic ring having a nitrile group or a cyano group such as benzonitrile or cyanobenzene, a carbonyl skeleton such as benzophenone, a phosphine oxide skeleton, a sulfone skeleton, etc. can be used. Thus, a π-electron-deficient skeleton and a π-electron-rich skeleton can be used instead of at least one of the π-electron-deficient heteroaromatic ring and the π-electron-rich heteroaromatic ring.

[0148] [Chemical formula]

[0149] Note that the TADF material is a material having a function in which the difference (ΔE ST ) between the S1 level and the T1 level is small and energy can be converted from the triplet excitation energy to the singlet excitation energy by reverse intersystem crossing. Therefore, up-conversion (reverse intersystem crossing) of the triplet excitation energy to the singlet excitation energy is possible with a small amount of thermal energy, and the singlet excited state can be efficiently generated. Further, the triplet excitation energy can be converted into light emission.

[0150] In addition, an exciplex (also referred to as an exciplex, exiplex, or Exciplex) that forms an excited state with two types of substances has ΔE ST which is extremely small and has a function as a TADF material capable of converting triplet excitation energy into singlet excitation energy.

[0151] Note that as an index for the T1 level, a phosphorescence spectrum observed at a low temperature (for example, from 77K to 10K) may be used. As for the TADF material, a tangent is drawn at the trailing edge on the short-wavelength side of its fluorescence spectrum, and the energy of the wavelength of the extrapolated line is taken as the S1 level. A tangent is drawn at the trailing edge on the short-wavelength side of the phosphorescence spectrum, and when the energy of the wavelength of the extrapolated line is taken as the T1 level, it is preferable that the difference between the S1 level and the T1 level is 0.3 eV or less, more preferably 0.2 eV or less, and even more preferably 0.1 eV or less.

[0152] In addition, when using a TADF material as a light-emitting substance, it is preferable that the S1 level of the host material is higher than the S1 level of the TADF material. Also, it is preferable that the T1 level of the host material is higher than the T1 level of the TADF material.

[0153] As the host material of the light-emitting layer, various carrier transport materials such as a material having electron-transporting properties, a material having hole-transporting properties, and the above TADF material can be used. In addition, since the organic compound of one aspect of the present invention also has bipolarity, it can be suitably used as a host material.

[0154] As materials having hole-transporting properties, organic compounds having an amine skeleton or a π-electron-rich heteroaromatic ring skeleton are preferred. For example, 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4'-bis[N-(spiro-9,9'-bifluorene-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluorene-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]spiro-9,9'-bifluorene-2-amine (abbreviation: PCBASF) and other compounds having an aromatic amine skeleton, 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP) and other compounds having a carbazole skeleton, 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,Compounds having a thiophene skeleton such as 8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III) and 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and compounds having a furan skeleton such as 4,4’,4’’-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II). Among the above, compounds having an aromatic amine skeleton and compounds having a carbazole skeleton are preferable because they have good reliability, high hole transportability, and contribute to reducing the driving voltage.,

[0155] As the material having electron transporting properties, for example, metal complexes such as bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq2), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (abbreviation: BAlq), bis(8-quinolinolato)zinc(II) (abbreviation: Znq), bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO), bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ), and organic compounds having a π-electron deficient heteroaromatic ring skeleton are preferred.Examples of the organic compound having a π-electron deficient heteroaromatic ring skeleton include heterocyclic compounds having a polyazole skeleton such as 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 2,2’,2’’-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II); heterocyclic compounds having a diazine skeleton such as 2-[3-(dibenzothiophen-4-yl)phenyl]dibenz[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3’-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenz[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3’-(9H-carbazol-9-yl)biphenyl-3-yl]dibenz[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 4,6-bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,8-bis[3-(dibenzothiophen-4-yl)phenyl]benzo[h]quinazoline (abbreviation: 4,8mDBtP2Bqn); and heterocyclic compounds having a pyridine skeleton such as 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy), 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB). Among the above, the heterocyclic compounds having a diazine skeleton and the heterocyclic compounds having a pyridine skeleton are preferable because of their good reliability.In particular, a heterocyclic compound having a diazine (pyrimidine or pyrazine) skeleton has high electron transport properties and also contributes to reducing the driving voltage.

[0156] As the TADF material that can be used as the host material, those previously mentioned as the TADF material can be used in the same manner. When the TADF material is used as the host material, the triplet excitation energy generated in the TADF material is converted into singlet excitation energy by reverse intersystem crossing, and further, by transferring the energy to the luminescent substance, the luminous efficiency of the light-emitting device can be increased. At this time, the TADF material functions as an energy donor, and the luminescent substance functions as an energy acceptor.

[0157] This is very effective when the above-mentioned luminescent substance is a fluorescent luminescent substance. Also, at this time, in order to obtain high luminous efficiency, it is preferable that the S1 level of the TADF material is higher than the S1 level of the fluorescent luminescent substance. Also, it is preferable that the T1 level of the TADF material is higher than the S1 level of the fluorescent luminescent substance. Therefore, it is preferable that the T1 level of the TADF material is higher than the T1 level of the fluorescent luminescent substance.

[0158] Also, it is preferable to use a TADF material that exhibits luminescence overlapping with the wavelength of the absorption band on the lowest energy side of the fluorescent luminescent substance. By doing so, the transfer of excitation energy from the TADF material to the fluorescent luminescent substance becomes smooth, and light emission can be obtained efficiently, which is preferable.

[0159] In addition, in order for singlet excitation energy to be efficiently generated from triplet excitation energy by reverse intersystem crossing, it is preferable that carrier recombination occurs in the TADF material. Further, it is preferable that the triplet excitation energy generated in the TADF material does not transfer to the triplet excitation energy of the fluorescent substance. For this purpose, it is preferable that the fluorescent substance has a protecting group around the lumophore (skeleton causing luminescence) of the fluorescent substance. As the protecting group, a substituent having no π bond is preferable, and a saturated hydrocarbon is preferable. Specifically, an alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 10 carbon atoms can be mentioned, and it is more preferable that there are a plurality of protecting groups. Since a substituent having no π bond has poor ability to transport carriers, it can increase the distance between the TADF material and the lumophore of the fluorescent substance with little influence on carrier transport and carrier recombination. Here, the lumophore refers to an atomic group (skeleton) that causes luminescence in the fluorescent substance. The lumophore preferably has a skeleton having a π bond, preferably contains an aromatic ring, and preferably has a condensed aromatic ring or a condensed heteroaromatic ring. Examples of the condensed aromatic ring or the condensed heteroaromatic ring include a phenanthrene skeleton, a stilbene skeleton, an acridone skeleton, a phenoxazine skeleton, and a phenothiazine skeleton. In particular, fluorescent substances having a naphthalene skeleton, an anthracene skeleton, a fluorene skeleton, a chrysene skeleton, a triphenylene skeleton, a tetracene skeleton, a pyrene skeleton, a perylene skeleton, a coumarin skeleton, a quinacridone skeleton, and a naphthobisbenzofuran skeleton are preferable because they have a high fluorescence quantum yield.

[0160] When using a fluorescent luminescent substance as the luminescent substance, as the host material, a material having an anthracene skeleton is preferable. When using a substance having an anthracene skeleton as the host material of the fluorescent luminescent substance, it is possible to realize a luminescent layer with both good luminous efficiency and durability. As the substance having an anthracene skeleton used as the host material, a substance having a diphenylanthracene skeleton, particularly a substance having a 9,10-diphenylanthracene skeleton, is preferable because it is chemically stable. Further, when the host material has a carbazole skeleton, it is preferable because the hole injection and transport properties are enhanced. However, when it contains a benzocarbazole skeleton in which a benzene ring is further condensed with carbazole, the HOMO becomes about 0.1 eV shallower than that of carbazole, and holes can easily enter, so it is more preferable. In particular, when the host material contains a dibenzocarbazole skeleton, the HOMO becomes about 0.1 eV shallower than that of carbazole, holes can easily enter, the hole transport property is excellent, and the heat resistance is also high, so it is suitable. Therefore, a substance having both a 9,10-diphenylanthracene skeleton and a carbazole skeleton (or a benzocarbazole skeleton or a dibenzocarbazole skeleton) is more preferable as the host material. From the above viewpoints of hole injection and transport properties, a benzofluorene skeleton or a dibenzofluorene skeleton may be used instead of the carbazole skeleton. Examples of such substances include 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: CzPA), 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA), 6-[3-(9,10-diphenyl-2-anthryl)phenyl]-benzo[b]naphtho[1,2-d]furan (abbreviation: 2mBnfPPA), 9-phenyl-10-{4-(9-phenyl-9H-fluoren-9-yl)biphenyl-4'-yl}anthracene (abbreviation: FLPPA), 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: αN-βNPAnth), and the like.In particular, CzPA, cgDBCzPA, 2mBnfPPA, and PCzPA are preferred choices because they exhibit very good properties.

[0161] Note that the host material may be a material obtained by mixing multiple substances. When using a mixed host material, it is preferable to mix a material having electron-transporting properties and a material having hole-transporting properties. By mixing a material having electron-transporting properties and a material having hole-transporting properties, the transport properties of the light-emitting layer 113 can be easily adjusted, and the recombination region can also be easily controlled. The weight ratio of the content of the material having hole-transporting properties to the material having electron-transporting properties may be Hole-transporting material : Electron-transporting material = 1:19 to 19:1. Note that, as the material having electron-transporting properties in the mixed host material, the organic compound described in Embodiment 1 can be preferably used.

[0162] Note that a phosphorescent light-emitting substance can be used as part of the above-mentioned mixed material. The phosphorescent light-emitting substance can be used as an energy donor that supplies excitation energy to the fluorescent light-emitting substance when the fluorescent light-emitting substance is used as the light-emitting substance.

[0163] Also, an exciplex may be formed between these mixed materials. By selecting a combination that forms an exciplex that exhibits emission overlapping with the wavelength of the absorption band on the lowest energy side of the light-emitting substance, energy transfer becomes smooth and efficient emission can be obtained, which is preferable. Also, since the driving voltage is reduced by using this configuration, it is preferable.

[0164] Note that at least one of the materials forming the exciplex may be a phosphorescent light-emitting substance. By doing so, the triplet excitation energy can be efficiently converted into singlet excitation energy by reverse intersystem crossing.

[0165] As a combination of materials that efficiently form an exciplex, it is preferable that the HOMO level of the hole-transporting material is equal to or higher than the HOMO level of the electron-transporting material. Also, it is preferable that the LUMO level of the hole-transporting material is equal to or higher than the LUMO level of the electron-transporting material. Note that the LUMO level and HOMO level of the material can be derived from the electrochemical properties (reduction potential and oxidation potential) of the material measured by cyclic voltammetry (CV) measurement.

[0166] Note that the formation of the exciplex can be confirmed, for example, by comparing the emission spectrum of the hole-transporting material, the emission spectrum of the electron-transporting material, and the emission spectrum of a mixed film of these materials, and observing the phenomenon that the emission spectrum of the mixed film is shifted to a longer wavelength (or has a new peak on the longer wavelength side) than the emission spectra of the individual materials. Alternatively, by comparing the transient photoluminescence (PL) of the hole-transporting material, the transient PL of the electron-transporting material, and the transient PL of a mixed film of these materials, and observing differences in transient responses such as the transient PL lifetime of the mixed film having a longer-lived component or a larger proportion of the delayed component than the transient PL lifetimes of the individual materials, it can be confirmed. Also, the above-mentioned transient PL may be read as transient electroluminescence (EL). That is, by comparing the transient EL of the hole-transporting material, the transient EL of the electron-transporting material, and the transient EL of a mixed film of these materials, and observing differences in transient responses, the formation of the exciplex can also be confirmed.

[0167] The electron transport layer 114 is a layer containing a substance having electron-transporting properties. As the substance having electron-transporting properties, those listed as substances having electron-transporting properties that can be used for the above host material can be used.

[0168] Note that the electron transport layer 114 has an electron mobility of 1×10 -7 cm 2 / Vs or more and 5×10 -5 cm 2It is preferably below / Vs. By reducing the electron transport property in the electron transport layer 114, the amount of electrons injected into the light-emitting layer can be controlled, and the light-emitting layer can be prevented from being in an electron-excessive state. Further, the electron transport layer preferably contains a material having electron transport property and an alkali metal or a simple substance, compound or complex of an alkali metal. These configurations are particularly preferable because the lifetime becomes good when the hole injection layer is formed as a composite material and the material having hole transport property in the composite material has a relatively deep HOMO level of -5.7 eV or more and -5.4 eV or less. At this time, the material having electron transport property preferably has a HOMO level of -6.0 eV or more. Further, the material having electron transport property is preferably an organic compound having an anthracene skeleton, and more preferably an organic compound containing both an anthracene skeleton and a heterocyclic skeleton. As the heterocyclic skeleton, a nitrogen-containing 5-membered ring skeleton or a nitrogen-containing 6-membered ring skeleton is preferable, and as these heterocyclic skeletons, a nitrogen-containing 5-membered ring skeleton or a nitrogen-containing 6-membered ring skeleton containing two heteroatoms in the ring such as a pyrazole ring, an imidazole ring, an oxazole ring, a thiazole ring, a pyrazine ring, a pyrimidine ring, a pyridazine ring, etc. is particularly preferable. Further, as the alkali metal or a simple substance, compound or complex of an alkali metal, it preferably contains an 8-hydroxyquinolinate structure. Specifically, for example, 8-hydroxyquinolinato-lithium (abbreviation: Liq), 8-hydroxyquinolinato-sodium (abbreviation: Naq), etc. can be mentioned. In particular, a complex of a monovalent metal ion, especially a complex of lithium, is preferable, and Liq is more preferable. When an 8-hydroxyquinolinate structure is included, a methyl-substituted product thereof (for example, a 2-methyl-substituted product or a 5-methyl-substituted product) can also be used. Further, in the electron transport layer, it is preferable that there is a concentration difference (including the case where it is 0) in the thickness direction of the alkali metal or a simple substance, compound or complex of an alkali metal.

[0169] Between the electron transport layer 114 and the second electrode 102, as an electron injection layer 115, a layer containing an alkali metal or an alkaline earth metal or a compound thereof such as lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF2), 8-hydroxyquinolinato-lithium (abbreviation: Liq), etc. may be provided. The electron injection layer 115 may be a layer in which an alkali metal or an alkaline earth metal or a compound thereof is contained in a layer made of a substance having electron transporting properties, or an electride may be used. Examples of electrides include substances obtained by adding electrons to a mixed oxide of calcium and aluminum at a high concentration.

[0170] Note that as the electron injection layer 115, a layer in which the fluoride of the above alkali metal or alkaline earth metal is contained in a concentration equal to or higher than the concentration at which it becomes a microcrystalline state (50 wt% or higher) in a substance having electron transporting properties (preferably an organic compound having a bipyridine skeleton) can also be used. Since the layer has a low refractive index, it is possible to provide a light-emitting device with better external quantum efficiency.

[0171] Alternatively, a charge generation layer 116 may be provided instead of the electron injection layer 115 (Fig. 1B). The charge generation layer 116 is a layer that can inject holes into the layer in contact with the cathode side of the layer and electrons into the layer in contact with the anode side by applying a potential. The charge generation layer 116 includes at least a P-type layer 117. The P-type layer 117 is preferably formed using the composite material listed as a material that can constitute the above-mentioned hole injection layer 111. The P-type layer 117 may also be formed by laminating a film containing the acceptor material described above and a film containing a hole transporting material as materials constituting the composite material. By applying a potential to the P-type layer 117, electrons are injected into the electron transport layer 114 and holes are injected into the second electrode 102 which is the cathode, and the light-emitting device operates.

[0172] Note that it is preferable that the charge generation layer 116 is provided with either or both of an electron relay layer 118 and an electron injection buffer layer 119 in addition to the P-type layer 117.

[0173] The electron relay layer 118 contains at least a substance having electron transporting properties, and has a function of preventing the interaction between the electron injection buffer layer 119 and the P-type layer 117 and smoothly transferring electrons. The LUMO level of the substance having electron transporting properties contained in the electron relay layer 118 is preferably between the LUMO level of the acceptor substance in the P-type layer 117 and the LUMO level of the substance contained in the layer in contact with the charge generation layer 116 in the electron transport layer 114. The specific energy level of the LUMO level in the substance having electron transporting properties used for the electron relay layer 118 is preferably -5.0 eV or higher, preferably -5.0 eV or higher and -3.0 eV or lower. In addition, as the substance having electron transporting properties used for the electron relay layer 118, it is preferable to use a phthalocyanine-based material or a metal complex having a metal-oxygen bond and an aromatic ligand.

[0174] For the electron injection buffer layer 119, it is possible to use substances with high electron injection properties such as alkali metals, alkaline earth metals, rare earth metals, and their compounds (including alkali metal compounds (oxides such as lithium oxide, halides, carbonates such as lithium carbonate and cesium carbonate), alkaline earth metal compounds (including oxides, halides, carbonates), or rare earth metal compounds (including oxides, halides, carbonates)).

[0175] In addition, when the electron injection buffer layer 119 is formed by including a substance having electron transporting properties and a donor substance, as the donor substance, in addition to alkali metals, alkaline earth metals, rare earth metals, and their compounds (including alkali metal compounds (oxides such as lithium oxide, halides, carbonates such as lithium carbonate and cesium carbonate), alkaline earth metal compounds (including oxides, halides, carbonates), or rare earth metal compounds (including oxides, halides, carbonates)), organic compounds such as tetrathianaphthacene (abbreviation: TTN), nickelocene, and decamethylnickelocene can also be used. In addition, as the substance having electron transporting properties, it can be formed using the same material as the material constituting the electron transport layer 114 described above.

[0176] As the material for forming the second electrode 102, a metal, alloy, electrically conductive compound, or a mixture thereof having a small work function (specifically, 3.8 eV or less) can be used. Specific examples of such cathode materials include alkali metals such as lithium (Li) and cesium (Cs), elements belonging to Group 1 or Group 2 of the periodic table such as magnesium (Mg), calcium (Ca), and strontium (Sr), and alloys containing these (MgAg, AlLi), rare earth metals such as europium (Eu) and ytterbium (Yb), and alloys containing these. However, by providing an electron injection layer between the second electrode 102 and the electron transport layer, various conductive materials such as Al, Ag, ITO, indium tin oxide containing silicon or silicon oxide, etc. can be used as the second electrode 102 regardless of the work function. These conductive materials can be formed into a film using dry methods such as vacuum evaporation and sputtering, inkjet methods, spin coating methods, etc. Further, it may be formed by a wet method using the sol-gel method, or may be formed by a wet method using a paste of a metal material.

[0177] Also, as a method for forming the EL layer 103, various methods can be used regardless of dry methods or wet methods. For example, a vacuum evaporation method, a gravure printing method, an offset printing method, a screen printing method, an inkjet method (droplet ejection method), or a spin coating method may be used.

[0178] Also, the above-described electrodes or layers may be formed using different film-forming methods.

[0179] Note that the configuration of the layer provided between the first electrode 101 and the second electrode 102 is not limited to the above. However, a configuration in which a light-emitting region where holes and electrons recombine is provided at a site away from the first electrode 101 and the second electrode 102 is preferred so as to suppress quenching caused by the proximity of the light-emitting region, the metal used for the electrodes and the carrier injection layer.

[0180] In addition, the hole transport layer and the electron transport layer in contact with the light-emitting layer 113, particularly the carrier transport layer close to the recombination region in the light-emitting layer 113, are preferably made of a material having a band gap larger than the band gap of the light-emitting material constituting the light-emitting layer or the band gap of the light-emitting material contained in the light-emitting layer in order to suppress energy transfer from the excitons generated in the light-emitting layer.

[0181] Here, a method of forming the EL layer 786 using the droplet discharge method will be described with reference to FIG. 2. FIGS. 2A to 2D are cross-sectional views for explaining a method of manufacturing the EL layer 786.

[0182] First, a conductive film 772 is formed on the planarized insulating film 770, and an insulating film 730 is formed so as to cover a part of the conductive film 772 (see FIG. 2A).

[0183] Next, droplets 784 are discharged from the droplet discharge device 783 onto the exposed portion of the conductive film 772, which is an opening of the insulating film 730, to form a layer 785 containing a composition. The droplets 784 are a composition containing a solvent and adhere to the conductive film 772 (see FIG. 2B).

[0184] Note that the step of discharging the droplets 784 may be performed under reduced pressure.

[0185] Next, the solvent is removed from the layer 785 containing the composition and solidified to form the EL layer 786 (see FIG. 2C).

[0186] Note that as a method for removing the solvent, a drying step or a heating step may be performed.

[0187] Next, a conductive film 788 is formed on the EL layer 786 to form a light-emitting device 782 (see FIG. 2D).

[0188] When the EL layer 786 containing a light-emitting substance is formed by the droplet discharge method in this way, the composition can be selectively discharged, so that material loss can be reduced. In addition, since a lithography process or the like for processing the shape is not required, the process can be simplified and cost reduction can be achieved.

[0189] The droplet ejection method described above is a general term for those having means for ejecting droplets, such as a nozzle having an ejection port of a composition, or a head having one or a plurality of nozzles.

[0190] Next, a droplet ejection device used in the droplet ejection method will be described with reference to FIG. 3. FIG. 3 is a conceptual diagram for explaining the droplet ejection device 1400.

[0191] The droplet ejection device 1400 has droplet ejection means 1403. The droplet ejection means 1403 includes a head 1405, a head 1412, and a head 1416.

[0192] The head 1405, the head 1412, and the head 1416 are connected to control means 1407, and can be drawn in a pattern programmed in advance by controlling it with a computer 1410.

[0193] As the timing for drawing, for example, it may be performed based on a marker 1411 formed on the substrate 1402. Alternatively, a reference point may be determined based on the outer edge of the substrate 1402. Here, the marker 1411 is detected by the imaging means 1404, converted into a digital signal by the image processing means 1409, recognized by the computer 1410 to generate a control signal, and sent to the control means 1407.

[0194] As the imaging means 1404, a charge-coupled device (CCD), an image sensor using a complementary metal-oxide-semiconductor (CMOS), or the like can be used. Note that the information on the pattern to be formed on the substrate 1402 is stored in the storage medium 1408, and based on this information, a control signal is sent to the control means 1407 to individually control the individual heads 1405, 1412, and 1416 of the droplet ejection means 1403. The materials to be ejected are supplied from the material supply sources 1413, 1414, and 1415 to the heads 1405, 1412, and 1416 through pipes, respectively.

[0195] Inside the heads 1405, 1412, and 1416, there is a space filled with a liquid material as indicated by the dotted line 1406 and a structure having nozzles as discharge ports. Although not shown, the heads 1412 and 1416 also have the same internal structure as the head 1405. If the nozzles of the heads 1405, 1412, and 1416 are provided with different sizes, different materials can be simultaneously drawn with different widths. With one head, multiple types of light-emitting materials and the like can be discharged and drawn respectively. When drawing in a wide area, in order to improve throughput, the same material can be simultaneously discharged and drawn from a plurality of nozzles. When using a large substrate, the heads 1405, 1412, and 1416 can freely scan on the substrate in the directions of the X, Y, and Z arrows shown in FIG. 3, freely set the area to be drawn, and draw the same pattern multiple times on one substrate.

[0196] Also, the step of discharging the composition may be performed under reduced pressure. The substrate may be heated during discharge. After discharging the composition, one or both of the steps of drying and firing are performed. The steps of drying and firing are both heat treatment steps, but their purposes, temperatures, and times are different. The drying step and the firing step are performed under normal pressure or reduced pressure by laser light irradiation, rapid thermal annealing, a heating furnace, or the like. Note that the timing of performing this heat treatment and the number of times of heat treatment are not particularly limited. In order to perform the drying and firing steps well, the temperature at that time depends on the material of the substrate and the properties of the composition.

[0197] As described above, the EL layer 786 can be fabricated using the droplet discharge device.

[0198] When manufacturing the EL layer 786 using a droplet ejection device, when forming by a wet method as a composition in which various organic materials or organic-inorganic halogen perovskites are dissolved or dispersed in a solvent, various organic solvents can be used to form a coating composition. Examples of the organic solvents that can be used in the composition include benzene, toluene, xylene, mesitylene, tetrahydrofuran, dioxane, ethanol, methanol, n-propanol, isopropanol, n-butanol, t-butanol, acetonitrile, dimethyl sulfoxide, dimethylformamide, chloroform, methylene chloride, carbon tetrachloride, ethyl acetate, hexane, cyclohexane and other various organic solvents. In particular, by using low-polarity benzene derivatives such as benzene, toluene, xylene, and mesitylene, a solution with a suitable concentration can be made, and it is preferable because it can prevent the materials contained in the ink from deteriorating due to oxidation or the like. Also, considering the uniformity of the film after production and the uniformity of the film thickness, etc., it is preferable that the boiling point is 100 °C or higher, and toluene, xylene, and mesitylene are more preferable.

[0199] Note that the above configuration can be appropriately combined with other embodiments or other configurations in this embodiment. Also, although FIGS. 2 and 3 show a method of forming the EL layer 786 as a single layer, it may be formed by laminating a plurality of layers. In that case, a wet method such as the droplet ejection method may be performed multiple times for lamination, or it may be laminated in combination with a vapor deposition method. Note that it is preferable to form from the hole injection (transport) layer to the light-emitting layer by a wet method such as the droplet ejection method, and to form from the electron transport layer to the cathode by a dry method such as a vapor deposition method or a sputtering method.

[0200] Next, an aspect of a light-emitting device having a structure in which a plurality of light-emitting units are stacked (also referred to as a stacked element or a tandem element) will be described with reference to FIG. 1C. This light-emitting device is a light-emitting device having a plurality of light-emitting units between an anode and a cathode. One light-emitting unit has substantially the same configuration as the EL layer 103 shown in FIG. 1A. That is, it can be said that the light-emitting device shown in FIG. 1C is a light-emitting device having a plurality of light-emitting units, and the light-emitting devices shown in FIGS. 1A or 1B are light-emitting devices having one light-emitting unit.

[0201] In FIG. 1C, a first light-emitting unit 511 and a second light-emitting unit 512 are stacked between an anode 501 and a cathode 502, and a charge generation layer 513 is provided between the first light-emitting unit 511 and the second light-emitting unit 512. The anode 501 and the cathode 502 correspond to the first electrode 101 and the second electrode 102 in FIG. 1A, respectively, and the same ones as those described in the description of FIG. 1A can be applied. Also, the first light-emitting unit 511 and the second light-emitting unit 512 may have the same configuration or different configurations.

[0202] The charge generation layer 513 has a function of injecting electrons into one light-emitting unit and holes into the other light-emitting unit when a voltage is applied to the anode 501 and the cathode 502. That is, in FIG. 1C, when a voltage is applied so that the potential of the anode is higher than the potential of the cathode, the charge generation layer 513 may inject electrons into the first light-emitting unit 511 and holes into the second light-emitting unit 512.

[0203] The charge generation layer 513 is preferably formed with the same configuration as the charge generation layer 116 described with reference to FIG. 1B. Since the composite material of the organic compound and the metal oxide is excellent in carrier injection property and carrier transport property, low-voltage driving and low-current driving can be realized. When the surface on the anode side of the light-emitting unit is in contact with the charge generation layer 513, the charge generation layer 513 can also serve as a hole injection layer of the light-emitting unit, so the light-emitting unit does not have to be provided with a hole injection layer.

[0204] Further, when the electron injection buffer layer 119 is provided in the charge generation layer 513, since the electron injection buffer layer 119 serves as the electron injection layer in the light-emitting unit on the anode side, it is not always necessary to form an electron injection layer in the light-emitting unit on the anode side.

[0205] In FIG. 1C, a light-emitting device having two light-emitting units has been described, but the present invention can be similarly applied to a light-emitting device in which three or more light-emitting units are stacked. By arranging a plurality of light-emitting units between a pair of electrodes with the charge generation layer 513 interposed therebetween as in the light-emitting device according to the present embodiment, high-brightness light emission can be achieved while keeping the current density low, and a longer-life element can be realized. Further, a light-emitting device that can be driven at a low voltage and has low power consumption can be realized.

[0206] Further, by making the emission colors of the respective light-emitting units different, light emission of a desired color can be obtained for the entire light-emitting device. For example, in a light-emitting device having two light-emitting units, a light-emitting device that emits white light as a whole can be obtained by obtaining emission colors of red and green in the first light-emitting unit and an emission color of blue in the second light-emitting unit.

[0207] Further, each layer and electrode such as the above-described EL layer 103, the first light-emitting unit 511, the second light-emitting unit 512, and the charge generation layer can be formed by using methods such as a vapor deposition method (including a vacuum vapor deposition method), a droplet discharge method (also referred to as an inkjet method), a coating method, and a gravure printing method. Further, they may contain a low molecular weight material, a medium molecular weight material (including an oligomer and a dendrimer), or a high molecular weight material.

[0208] (Embodiment 3) In the present embodiment, a light-emitting device using the light-emitting device described in Embodiment 2 will be described.

[0209] In this embodiment, a light-emitting device manufactured using the light-emitting device described in Embodiment 2 will be described with reference to FIG. 4. Note that FIG. 4A is a top view showing the light-emitting device, and FIG. 4B is a cross-sectional view obtained by cutting FIG. 4A along A-B and C-D. This light-emitting device includes a drive circuit portion (source line drive circuit) 601, a pixel portion 602, and a drive circuit portion (gate line drive circuit) 603, which are indicated by dotted lines, as means for controlling the light emission of the light-emitting device. Further, 604 is a sealing substrate, and 605 is a sealing material. The inside surrounded by the sealing material 605 is a space 607.

[0210] Note that the routing wiring 608 is a wiring for transmitting signals input to the source line drive circuit 601 and the gate line drive circuit 603, and receives a video signal, a clock signal, a start signal, a reset signal, etc. from an FPC (Flexible Printed Circuit) 609 serving as an external input terminal. Although only the FPC is illustrated here, a printed wiring board (PWB) may be attached to this FPC. The light-emitting device in this specification includes not only the light-emitting device main body but also a state in which an FPC or a PWB is attached thereto.

[0211] Next, the cross-sectional structure will be described with reference to FIG. 4B. Although a drive circuit portion and a pixel portion are formed on the element substrate 610, here, the source line drive circuit 601, which is a drive circuit portion, and one pixel in the pixel portion 602 are shown.

[0212] The element substrate 610 may be manufactured using a plastic substrate made of FRP (Fiber Reinforced Plastics), PVF (polyvinyl fluoride), polyester, acrylic resin, etc., in addition to a substrate made of glass, quartz, organic resin, metal, alloy, semiconductor, or the like.

[0213] The structure of the transistor used for the pixel and the driving circuit is not particularly limited. For example, it may be an inverted staggered transistor or a staggered transistor. Also, it may be a top gate transistor or a bottom gate transistor. The semiconductor material used for the transistor is not particularly limited, and for example, silicon, germanium, silicon carbide, gallium nitride, etc. can be used. Alternatively, an oxide semiconductor containing at least one of indium, gallium, and zinc, such as an In-Ga-Zn-based metal oxide, may be used.

[0214] The crystallinity of the semiconductor material used for the transistor is also not particularly limited, and any of an amorphous semiconductor, a semiconductor having crystallinity (microcrystalline semiconductor, polycrystalline semiconductor, single crystal semiconductor, or a semiconductor having a crystalline region in part) may be used. Using a semiconductor having crystallinity is preferable because deterioration of transistor characteristics can be suppressed.

[0215] Here, in addition to the transistor provided in the pixel and the driving circuit, for semiconductor devices such as transistors used for a touch sensor described later, it is preferable to apply an oxide semiconductor. In particular, it is preferable to apply an oxide semiconductor having a wider bandgap than silicon. By using an oxide semiconductor having a wider bandgap than silicon, the current in the off state of the transistor can be reduced.

[0216] The above oxide semiconductor preferably contains at least indium (In) or zinc (Zn). Further, it is more preferable that it is an oxide semiconductor containing an oxide represented by In-M-Zn-based oxide (M is a metal such as Al, Ti, Ga, Ge, Y, Zr, Sn, La, Ce, or Hf).

[0217] In particular, as the semiconductor layer, it is preferable to use an oxide semiconductor film having a plurality of crystal parts, where the c-axis of the crystal part is oriented perpendicular to the surface to be formed of the semiconductor layer or the upper surface of the semiconductor layer, and there is no grain boundary between adjacent crystal parts.

[0218] By using such a material as the semiconductor layer, fluctuations in electrical characteristics can be suppressed, and a highly reliable transistor can be realized.

[0219] In addition, due to its low off-current, the transistor having the above-described semiconductor layer can hold the charge accumulated in the capacitor via the transistor for a long period of time. By applying such a transistor to a pixel, it is also possible to stop the drive circuit while maintaining the gradation of the image displayed in each display area. As a result, an electronic device with extremely low power consumption can be realized.

[0220] For the purpose of stabilizing the characteristics of the transistor, etc., it is preferable to provide an underlying film. As the underlying film, an inorganic insulating film such as a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a silicon nitride oxide film can be used, and it can be formed as a single layer or by lamination. The underlying film can be formed using a sputtering method, a CVD (Chemical Vapor Deposition) method (such as a plasma CVD method, a thermal CVD method, an MOCVD (Metal Organic CVD) method, etc.), an ALD (Atomic Layer Deposition) method, a coating method, a printing method, etc. Note that the underlying film may not be provided if it is not necessary.

[0221] Note that FET623 indicates one of the transistors formed in the drive circuit section 601. Also, the drive circuit may be formed of various CMOS circuits, PMOS circuits, or NMOS circuits. In addition, in the present embodiment, a driver integrated type in which the drive circuit is formed on the substrate is shown, but this is not necessarily required, and the drive circuit can also be formed outside the substrate instead of on the substrate.

[0222] In addition, the pixel section 602 is formed of a plurality of pixels including a switching FET611, a current control FET612, and a first electrode 613 electrically connected to its drain, but is not limited thereto, and a pixel section combining three or more FETs and a capacitor element may also be used.

[0223] Note that an insulator 614 is formed to cover the end portion of the first electrode 613. Here, it can be formed by using a positive photosensitive acrylic resin film.

[0224] In addition, in order to make the coating properties of the EL layer and the like formed later good, a curved surface having a curvature is formed at the upper end portion or the lower end portion of the insulator 614. For example, when a positive photosensitive acrylic resin is used as the material of the insulator 614, it is preferable to provide a curved surface having a curvature radius (0.2 μm to 3 μm) only at the upper end portion of the insulator 614. Also, as the insulator 614, either a negative photosensitive resin or a positive photosensitive resin can be used.

[0225] An EL layer 616 and a second electrode 617 are respectively formed on the first electrode 613. Here, as the material used for the first electrode 613 that functions as an anode, it is desirable to use a material having a large work function. For example, in addition to single-layer films such as ITO films, indium tin oxide films containing silicon, indium oxide films containing 2 to 20 wt% of zinc oxide, titanium nitride films, chromium films, tungsten films, Zn films, Pt films, etc., a laminate of a titanium nitride film and a film mainly composed of aluminum, a three-layer structure of a titanium nitride film, a film mainly composed of aluminum, and a titanium nitride film can be used. Note that when a laminated structure is used, the resistance as wiring is low, good ohmic contact can be achieved, and it can further function as an anode.

[0226] Also, the EL layer 616 is formed by various methods such as a vapor deposition method using a vapor deposition mask, an inkjet method, and a spin coating method. Also, as other materials constituting the EL layer 616, a low molecular compound or a high molecular compound (including oligomers and dendrimers) may be used.

[0227] Furthermore, as the material used for the second electrode 617 formed on the EL layer 616 and functioning as a cathode, it is preferable to use a material with a small work function (such as Al, Mg, Li, Ca, or an alloy or compound thereof (MgAg, MgIn, AlLi, etc.)). When the light generated in the EL layer 616 passes through the second electrode 617, it is preferable to use a laminate of a thin metal film with a reduced film thickness and a transparent conductive film (such as ITO, indium oxide containing 2 to 20 wt% zinc oxide, indium tin oxide containing silicon, zinc oxide (ZnO), etc.) as the second electrode 617.

[0228] Note that a light-emitting device 618 is formed by the first electrode 613, the EL layer 616, and the second electrode 617. The light-emitting device is the light-emitting device described in Embodiment 2. The pixel portion is formed of a plurality of light-emitting devices. In the light-emitting device of the present embodiment, both the light-emitting device described in Embodiment 2 and the light-emitting device having other configurations may be mixed.

[0229] Furthermore, by bonding the sealing substrate 604 to the element substrate 610 with the sealing material 605, a structure is formed in which the light-emitting device 618 is provided in a space 607 surrounded by the element substrate 610, the sealing substrate 604, and the sealing material 605. The space 607 is filled with a filling material, and in addition to the case where an inert gas (such as nitrogen or argon) is filled, it may also be filled with a sealing material. It is a preferable configuration to form a recess in the sealing substrate and provide a drying material therein to suppress deterioration due to the influence of moisture.

[0230] Note that it is preferable to use an epoxy-based resin or glass frit for the sealing material 605. These materials are desirably materials that do not transmit moisture and oxygen as much as possible. In addition to a glass substrate or a quartz substrate, a plastic substrate made of FRP (Fiber Reinforced Plastics), PVF (polyvinyl fluoride), polyester, acrylic resin, or the like can be used as the material for the sealing substrate 604.

[0231] Although not shown in FIG. 4, a protective film may be provided on the second electrode. The protective film may be formed of an organic resin film or an inorganic insulating film. Further, the protective film may be formed so as to cover the exposed portion of the sealing material 605. Further, the protective film can be provided to cover the exposed sides of the surfaces and sides of the pair of substrates, the sealing layer, the insulating layer, etc.

[0232] For the protective film, a material that is difficult to permeate impurities such as water can be used. Therefore, it is possible to effectively suppress the diffusion of impurities such as water from the outside to the inside.

[0233] As materials constituting the protective film, oxides, nitrides, fluorides, sulfides, ternary compounds, metals, polymers, etc. can be used. For example, materials containing aluminum oxide, hafnium oxide, hafnium silicate, lanthanum oxide, silicon oxide, strontium titanate, tantalum oxide, titanium oxide, zinc oxide, niobium oxide, zirconium oxide, tin oxide, yttrium oxide, cerium oxide, scandium oxide, erbium oxide, vanadium oxide or indium oxide, etc., materials containing aluminum nitride, hafnium nitride, silicon nitride, tantalum nitride, titanium nitride, niobium nitride, molybdenum nitride, zirconium nitride or gallium nitride, etc., materials containing nitrides containing titanium and aluminum, oxides containing titanium and aluminum, oxides containing aluminum and zinc, sulfides containing manganese and zinc, sulfides containing cerium and strontium, oxides containing erbium and aluminum, oxides containing yttrium and zirconium, etc. can be used.

[0234] The protective film is preferably formed using a film-forming method with good step coverage. One such technique is the atomic layer deposition (ALD) method. It is preferable to use a material that can be formed by the ALD method for the protective film. By using the ALD method, a protective film that is dense, has reduced defects such as cracks and pinholes, or has a uniform thickness can be formed. Also, the damage to the processing member when forming the protective film can be reduced.

[0235] For example, by forming a protective film using the ALD method, a protective film that is uniform and has few defects can be formed on a surface with a complex uneven shape, as well as on the upper, side, and back surfaces of a touch panel.

[0236] As described above, a light-emitting device manufactured using the light-emitting device described in Embodiment 2 can be obtained.

[0237] Since the light-emitting device in the present embodiment uses the light-emitting device described in Embodiment 2, a light-emitting device with good characteristics can be obtained. Specifically, since the light-emitting device described in Embodiment 2 has good luminous efficiency, it is possible to obtain a light-emitting device with low power consumption.

[0238] FIG. 5 shows an example of a light-emitting device that forms a light-emitting device exhibiting white light emission and is colorized by providing a coloring layer (color filter) or the like. FIG. 5A shows a substrate 1001, an underlying insulating film 1002, a gate insulating film 1003, gate electrodes 1006, 1007, 1008, a first interlayer insulating film 1020, a second interlayer insulating film 1021, a peripheral portion 1042, a pixel portion 1040, a driving circuit portion 1041, first electrodes 1024W, 1024R, 1024G, 1024B of the light-emitting device, a partition wall 1025, an EL layer 1028, a second electrode 1029 of the light-emitting device, a sealing substrate 1031, a sealing material 1032, etc.

[0239] In addition, in FIG. 5A, the coloring layers (red coloring layer 1034R, green coloring layer 1034G, blue coloring layer 1034B) are provided on the transparent substrate 1033. A black matrix 1035 may be further provided. The transparent substrate 1033 provided with the coloring layers and the black matrix is aligned and fixed to the substrate 1001. Note that the coloring layers and the black matrix 1035 are covered with an overcoat layer 1036. In FIG. 5A, there are a light-emitting layer through which light does not pass through the coloring layer and exits to the outside, and a light-emitting layer through which light passes through each coloring layer and exits to the outside. Since the light that does not pass through the coloring layer is white and the light that passes through the coloring layer is red, green, or blue, an image can be expressed with four-color pixels.

[0240] FIG. 5B shows an example in which the coloring layers (red coloring layer 1034R, green coloring layer 1034G, blue coloring layer 1034B) are formed between the gate insulating film 1003 and the first interlayer insulating film 1020. In this manner, the coloring layers may be provided between the substrate 1001 and the sealing substrate 1031.

[0241] In addition, in the light-emitting device described above, a light-emitting device having a structure in which light is extracted from the side of the substrate 1001 on which the FET is formed (bottom emission type) is used, but a light-emitting device having a structure in which light is extracted from the side of the sealing substrate 1031 (top emission type) may be used. A cross-sectional view of the top emission type light-emitting device is shown in FIG. 6. In this case, a substrate that does not transmit light can be used as the substrate 1001. Until a connection electrode connecting the FET and the anode of the light-emitting device is formed, it is formed in the same manner as the bottom emission type light-emitting device. Thereafter, a third interlayer insulating film 1037 is formed to cover the electrode 1022. This insulating film may serve as a planarization film. The third interlayer insulating film 1037 can be formed using the same material as the second interlayer insulating film or other known materials.

[0242] The first electrodes 1024W, 1024R, 1024G, and 1024B of the light-emitting device are anodes here, but they may also be cathodes. Further, in the case of a top-emission type light-emitting device as shown in FIG. 6, it is preferable that the first electrode be a reflective electrode. The configuration of the EL layer 1028 is the same as the configuration described for the EL layer 103 in Embodiment 2, and the element structure is such that white light emission can be obtained.

[0243] In the top-emission structure as shown in FIG. 6, sealing can be performed with a sealing substrate 1031 provided with a coloring layer (red coloring layer 1034R, green coloring layer 1034G, blue coloring layer 1034B). A black matrix 1035 may be provided on the sealing substrate 1031 so as to be located between pixels. The coloring layer (red coloring layer 1034R, green coloring layer 1034G, blue coloring layer 1034B) and the black matrix may be covered with an overcoat layer 1036. Note that a substrate having translucency is used as the sealing substrate 1031. Here, an example of full-color display using four colors of red, green, blue, and white is shown, but it is not particularly limited, and full-color display may be performed using four colors of red, yellow, green, and blue or three colors of red, green, and blue.

[0244] In a top-emission type light-emitting device, application of a microcavity structure can be suitably performed. A light-emitting device having a microcavity structure is obtained by using a first electrode as a reflective electrode and a second electrode as a semi-transmissive / semi-reflective electrode. At least an EL layer is provided between the reflective electrode and the semi-transmissive / semi-reflective electrode, and at least a light-emitting layer serving as a light-emitting region is provided.

[0245] Note that the reflective electrode has a visible light reflectance of 40% to 100%, preferably 70% to 100%, and a resistivity of 1×10 -2 Ωcm or less. Further, the semi-transmissive / semi-reflective electrode has a visible light reflectance of 20% to 80%, preferably 40% to 70%, and a resistivity of 1×10 -2 Ωcm or less.

[0246] The light emitted from the light-emitting layer contained in the EL layer is reflected by the reflective electrode and the semi-transmissive / semi-reflective electrode and resonates.

[0247] In the light-emitting device, the optical distance between the reflective electrode and the semi-transmissive / semi-reflective electrode can be changed by changing the thicknesses of the transparent conductive film, the above-described composite material, the carrier transport material, and the like. Thereby, between the reflective electrode and the semi-transmissive / semi-reflective electrode, light of a resonant wavelength can be enhanced and light of a non-resonant wavelength can be attenuated.

[0248] Note that, since the light (first reflected light) reflected by the reflective electrode and returned causes significant interference with the light (first incident light) directly incident from the light-emitting layer on the semi-transmissive / semi-reflective electrode, it is preferable to adjust the optical distance between the reflective electrode and the light-emitting layer to (2n−1)λ / 4 (where n is a natural number of 1 or more and λ is the wavelength of the light to be amplified). By adjusting the optical distance, the phases of the first reflected light and the first incident light can be matched to further amplify the light emitted from the light-emitting layer.

[0249] In the above configuration, the EL layer may have a structure having a plurality of light-emitting layers or a structure having a single light-emitting layer. For example, in combination with the configuration of the above-described tandem-type light-emitting device, a plurality of EL layers may be provided with a charge generation layer interposed therebetween in one light-emitting device, and a single or a plurality of light-emitting layers may be formed in each EL layer.

[0250] By having a microcavity structure, it becomes possible to enhance the forward emission intensity of a specific wavelength, and thus power consumption can be reduced. In the case of a light-emitting device that displays an image with four sub-pixels of red, yellow, green, and blue, in addition to the luminance improvement effect by yellow light emission, a microcavity structure adapted to the wavelength of each color can be applied to all sub-pixels, so that a light-emitting device with good characteristics can be obtained.

[0251] Since the light-emitting device in this embodiment uses the light-emitting device described in Embodiment 2, a light-emitting device having good characteristics can be obtained. Specifically, since the light-emitting device described in Embodiment 2 has good luminous efficiency, it is possible to obtain a light-emitting device with low power consumption.

[0252] So far, the active matrix type light-emitting device has been described. Hereinafter, the passive matrix type light-emitting device will be described. FIG. 7 shows a passive matrix type light-emitting device manufactured by applying the present invention. Note that FIG. 7A is a perspective view showing the light-emitting device, and FIG. 7B is a cross-sectional view obtained by cutting FIG. 7A along X-Y. In FIG. 7, on a substrate 951, an EL layer 955 is provided between an electrode 952 and an electrode 956. The end of the electrode 952 is covered with an insulating layer 953. And a partition layer 954 is provided on the insulating layer 953. The side walls of the partition layer 954 have an inclination such that the distance between one side wall and the other side wall becomes narrower as it approaches the substrate surface. That is, the cross-section in the short side direction of the partition layer 954 is trapezoidal, and the bottom side (the side facing the same direction as the surface direction of the insulating layer 953 and in contact with the insulating layer 953) is shorter than the upper side (the side facing the same direction as the surface direction of the insulating layer 953 and not in contact with the insulating layer 953). By providing the partition layer 954 in this way, it is possible to prevent defects in the light-emitting device caused by static electricity or the like. Also, in the passive matrix type light-emitting device, the light-emitting device described in Embodiment 2 is used, and a light-emitting device with good reliability or a light-emitting device with low power consumption can be obtained.

[0253] As described above, the light-emitting device can be suitably used as a display device for displaying an image because it is possible to control a large number of minute light-emitting devices arranged in a matrix.

[0254] In addition, this embodiment can be freely combined with other embodiments.

[0255] (Embodiment 4) In this embodiment, an example in which the light-emitting device described in Embodiment 2 is used as an illumination device will be described with reference to FIG. 8. FIG. 8B is a top view of the illumination device, and FIG. 8A is a cross-sectional view taken along the line e-f in FIG. 8B.

[0256] In the illumination device according to this embodiment, a first electrode 401 is formed on a translucent substrate 400 serving as a support. The first electrode 401 corresponds to the first electrode 101 in Embodiment 2. When extracting light emission from the first electrode 401 side, the first electrode 401 is formed of a translucent material.

[0257] A pad 412 for supplying a voltage to the second electrode 404 is formed on the substrate 400.

[0258] An EL layer 403 is formed on the first electrode 401. The EL layer 403 corresponds to the configuration of the EL layer 103 in Embodiment 2, or the configuration combining the first light-emitting unit 511, the second light-emitting unit 512, and the charge generation layer 513. For these configurations, refer to the relevant description.

[0259] The second electrode 404 is formed to cover the EL layer 403. The second electrode 404 corresponds to the second electrode 102 in Embodiment 2. When extracting light emission from the first electrode 401 side, the second electrode 404 is formed of a material with high reflectivity. The second electrode 404 is connected to the pad 412 to supply a voltage.

[0260] As described above, the illumination device according to this embodiment includes a light-emitting device having the first electrode 401, the EL layer 403, and the second electrode 404. Since the light-emitting device has high luminous efficiency, the illumination device according to this embodiment can be an illumination device with low power consumption.

[0261] A substrate 400 on which a light-emitting device having the above-described configuration is formed and a sealing substrate 407 are fixed and sealed using sealing materials 405 and 406, thereby completing the lighting device. Either of the sealing materials 405 and 406 may be used. Also, a desiccant can be mixed into the inner sealing material 406 (not shown in FIG. 8B), whereby moisture can be adsorbed, leading to an improvement in reliability.

[0262] Also, by extending a part of the pad 412 and the first electrode 401 outside the sealing materials 405 and 406, an external input terminal can be formed. Also, an IC chip 420 or the like on which a converter or the like is mounted may be provided thereon.

[0263] As described above, the lighting device according to the present embodiment uses the light-emitting device described in Embodiment 2 for the EL element, and can be a light-emitting device with low power consumption.

[0264] (Embodiment 5) In the present embodiment, an example of an electronic device including the light-emitting device described in Embodiment 2 in a part thereof will be described. The light-emitting device described in Embodiment 2 is a light-emitting device with good luminous efficiency and low power consumption. As a result, the electronic device described in the present embodiment can be an electronic device having a light-emitting part with low power consumption.

[0265] Examples of electronic devices to which the above light-emitting device is applied include, for example, a television device (also referred to as a TV or a television receiver), a monitor for a computer, a digital camera, a digital video camera, a digital photo frame, a mobile phone (also referred to as a cellular phone or a mobile phone device), a portable game machine, a portable information terminal, an audio reproduction device, and a large game machine such as a pachinko machine. Specific examples of these electronic devices are shown below.

[0266] FIG. 9A shows an example of a television apparatus. In the television apparatus, a display unit 7103 is incorporated in a housing 7101. Here, a configuration is shown in which the housing 7101 is supported by a stand 7105. The display unit 7103 can display images, and the display unit 7103 is configured by arranging the light-emitting devices described in Embodiment 2 in a matrix.

[0267] The operation of the television apparatus can be performed by an operation switch provided in the housing 7101 or a separate remote control operation unit 7110. Channel and volume operations can be performed by operation keys 7109 provided in the remote control operation unit 7110, and the images displayed on the display unit 7103 can be operated. Further, the remote control operation unit 7110 may be configured to include a display unit 7107 that displays information output from the remote control operation unit 7110.

[0268] Note that the television apparatus has a configuration including a receiver and a modem. The receiver can receive general television broadcasts, and can also perform one-way (from sender to receiver) or two-way (between sender and receiver, or between receivers) information communication by connecting to a communication network by wire or wirelessly via the modem.

[0269] Fig. 9B1 is a computer, which includes a main body 7201, a housing 7202, a display unit 7203, a keyboard 7204, an external connection port 7205, a pointing device 7206, etc. Note that this computer is manufactured by arranging the light-emitting devices described in Embodiment 2 in a matrix and using them for the display unit 7203. The computer in Fig. 9B1 may be in the form as shown in Fig. 9B2. The computer in Fig. 9B2 is provided with a second display unit 7210 instead of the keyboard 7204 and the pointing device 7206. The second display unit 7210 is of a touch panel type, and input can be performed by operating the input display shown on the second display unit 7210 with a finger or a dedicated pen. In addition, the second display unit 7210 can display not only the input display but also other images. The display unit 7203 may also be a touch panel. By connecting the two screens with a hinge, it is possible to prevent problems such as damage to the screens during storage or transportation.

[0270] Fig. 9C shows an example of a mobile terminal. The mobile phone includes, in addition to a display unit 7402 incorporated in a housing 7401, operation buttons 7403, an external connection port 7404, a speaker 7405, a microphone 7406, etc. Note that the mobile phone is provided with a display unit 7402 manufactured by arranging the light-emitting devices described in Embodiment 2 in a matrix.

[0271] The mobile terminal shown in Fig. 9C can also be configured such that information can be input by touching the display unit 7402 with a finger or the like. In this case, operations such as making a call or creating an email can be performed by touching the display unit 7402 with a finger or the like.

[0272] The screen of the display unit 7402 mainly has three modes. The first is a display mode mainly for displaying images, the second is an input mode mainly for inputting information such as characters, and the third is a display + input mode in which the two modes of the display mode and the input mode are mixed.

[0273] For example, when making a phone call or creating an email, the display unit 7402 may be set to a character input mode mainly for character input, and an input operation on the characters displayed on the screen may be performed. In this case, it is preferable to display a keyboard or number buttons on most of the screen of the display unit 7402.

[0274] In addition, by providing a detection device having sensors such as a gyro and an acceleration sensor inside the mobile terminal to detect the inclination, the orientation (portrait or landscape) of the mobile terminal can be determined, and the screen display of the display unit 7402 can be automatically switched.

[0275] In addition, the switching of the screen mode is performed by touching the display unit 7402 or operating the operation button 7403 of the housing 7401. It can also be switched according to the type of image displayed on the display unit 7402. For example, if the image signal displayed on the display unit is video data, it is switched to the display mode, and if it is text data, it is switched to the input mode.

[0276] In addition, in the input mode, the signal detected by the optical sensor of the display unit 7402 is detected, and when there is no touch operation on the display unit 7402 for a certain period, the screen mode may be controlled to be switched from the input mode to the display mode.

[0277] The display unit 7402 can also function as an image sensor. For example, by touching the display unit 7402 with a palm or a finger and imaging a palm print, a fingerprint, etc., personal authentication can be performed. In addition, if a backlight that emits near-infrared light or a sensing light source that emits near-infrared light is used for the display unit, finger veins, palm veins, etc. can also be imaged.

[0278] FIG. 10A is a schematic diagram showing an example of a cleaning robot.

[0279] The cleaning robot 5100 has a display 5101 arranged on the upper surface, a plurality of cameras 5102, a brush 5103, and operation buttons 5104 arranged on the side surface. Although not shown, the lower surface of the cleaning robot 5100 is provided with tires, a suction port, and the like. The cleaning robot 5100 is also provided with various sensors such as an infrared sensor, an ultrasonic sensor, an acceleration sensor, a piezo sensor, a light sensor, and a gyro sensor. In addition, the cleaning robot 5100 is provided with wireless communication means.

[0280] The cleaning robot 5100 can move automatically, detect dust 5120, and suck the dust from the suction port provided on the lower surface.

[0281] In addition, the cleaning robot 5100 can analyze the image captured by the camera 5102 and determine the presence or absence of obstacles such as walls, furniture, or steps. Also, when an object that is likely to get caught in the brush 5103, such as wiring, is detected by image analysis, the rotation of the brush 5103 can be stopped.

[0282] The display 5101 can display the remaining battery level, the amount of sucked dust, and the like. The path traveled by the cleaning robot 5100 may be displayed on the display 5101. Also, the display 5101 may be a touch panel, and the operation buttons 5104 may be provided on the display 5101.

[0283] The cleaning robot 5100 can communicate with a portable electronic device 5140 such as a smartphone. The image captured by the camera 5102 can be displayed on the portable electronic device 5140. Therefore, the owner of the cleaning robot 5100 can know the state of the room even when away from home. Also, the display on the display 5101 can be confirmed on a portable electronic device such as a smartphone.

[0284] The light-emitting device according to one aspect of the present invention can be used for the display 5101.

[0285] The robot 2100 shown in FIG. 10B includes an arithmetic unit 2110, an illuminance sensor 2101, a microphone 2102, an upper camera 2103, a speaker 2104, a display 2105, a lower camera 2106, an obstacle sensor 2107, and a moving mechanism 2108.

[0286] The microphone 2102 has a function of detecting the user's voice, environmental sounds, etc. Also, the speaker 2104 has a function of emitting sound. The robot 2100 can communicate with the user using the microphone 2102 and the speaker 2104.

[0287] The display 2105 has a function of displaying various information. The robot 2100 can display the information desired by the user on the display 2105. The display 2105 may be equipped with a touch panel. Also, the display 2105 may be a removable information terminal, and by installing it at a fixed position of the robot 2100, charging and data transfer are made possible.

[0288] The upper camera 2103 and the lower camera 2106 have a function of imaging the surroundings of the robot 2100. Also, the obstacle sensor 2107 can detect the presence or absence of obstacles in the traveling direction when the robot 2100 moves forward using the moving mechanism 2108. The robot 2100 can recognize the surrounding environment and move safely using the upper camera 2103, the lower camera 2106, and the obstacle sensor 2107. The light-emitting device according to one aspect of the present invention can be used for the display 2105.

[0289] FIG. 10C is a diagram showing an example of a goggle-type display. The goggle-type display includes, for example, a housing 5000, a display unit 5001, a speaker 5003, an LED lamp 5004, a connection terminal 5006, a sensor 5007 (including a function of measuring force, displacement, position, speed, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, voice, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared rays), a microphone 5008, a display unit 5002, a support unit 5012, earphones 5013, etc.

[0290] The light-emitting device according to one aspect of the present invention can be used for the display unit 5001 and the display unit 5002.

[0291] FIG. 11 is an example in which the light-emitting device described in Embodiment 2 is used in an electric stand which is a lighting device. The electric stand shown in FIG. 11 has a housing 2001 and a light source 2002, and as the light source 2002, the lighting device described in Embodiment 3 may be used.

[0292] FIG. 12 is an example in which the light-emitting device described in Embodiment 2 is used as an indoor lighting device 3001. Since the light-emitting device described in Embodiment 2 is a light-emitting device with high luminous efficiency, it can be used as a lighting device with low power consumption. In addition, since the light-emitting device described in Embodiment 2 can be made large in area, it can be used as a large-area lighting device. Further, since the light-emitting device described in Embodiment 2 is thin, it can be used as a thin lighting device.

[0293] The light-emitting device described in Embodiment 2 can also be mounted on the windshield and dashboard of an automobile. FIG. 13 shows an aspect in which the light-emitting device described in Embodiment 2 is used for the windshield and dashboard of an automobile. The display areas 5200 to 5203 are displays provided using the light-emitting device described in Embodiment 2.

[0294] The display area 5200 and the display area 5201 are display devices equipped with the light-emitting device described in Embodiment 2 provided on the windshield of an automobile. By fabricating the first electrode and the second electrode with light-transmissive electrodes, the light-emitting device described in Embodiment 2 can be a so-called see-through display device where the opposite side can be seen through. In the case of a see-through display, even if it is installed on the windshield of an automobile, it can be installed without obstructing the view. When providing transistors or the like for driving, it is preferable to use light-transmissive transistors such as organic transistors made of organic semiconductor materials or transistors using oxide semiconductors.

[0295] The display area 5202 is a display device equipped with the light-emitting device described in Embodiment 2 provided on the pillar portion. By projecting the video from the imaging means provided on the vehicle body, the view blocked by the pillar can be complemented. Similarly, the display area 5203 provided on the dashboard portion can compensate for the blind spot and enhance safety by projecting the video from the imaging means provided outside the automobile to complement the view blocked by the vehicle body. By projecting the video so as to complement the invisible part, safety confirmation can be performed more naturally without a sense of incongruity.

[0296] The display area 5203 can also provide various other information such as navigation information, speedometer, and tachometer settings. The display items and layout can be changed as appropriate according to the user's preference. Note that this information can also be provided in the display areas 5200 to 5202. In addition, the display areas 5200 to 5203 can also be used as lighting devices.

[0297] Further, FIGS. 14A and 14B show a foldable mobile information terminal 5150. The foldable mobile information terminal 5150 includes a housing 5151, a display area 5152, and a bending portion 5153. FIG. 14A shows the mobile information terminal 5150 in an unfolded state. FIG. 14B shows the mobile information terminal in a folded state. Despite having a large display area 5152, the mobile information terminal 5150 can be folded into a compact size and has excellent portability.

[0298] The display area 5152 can be folded in half by the bending portion 5153. The bending portion 5153 is composed of a stretchable member and a plurality of support members. When folding, the stretchable member extends. The bending portion 5153 is folded with a radius of curvature of 2 mm or more, preferably 3 mm or more.

[0299] Note that the display area 5152 may be a touch panel (input / output device) equipped with a touch sensor (input device). The light-emitting device according to one aspect of the present invention can be used for the display area 5152.

[0300] Further, FIGS. 15A to 15C show a foldable mobile information terminal 9310. FIG. 15A shows the mobile information terminal 9310 in an unfolded state. FIG. 15B shows the mobile information terminal 9310 in a state during the change from one of the unfolded state or the folded state to the other. FIG. 15C shows the mobile information terminal 9310 in a folded state. The mobile information terminal 9310 has excellent portability in the folded state and excellent display comprehensibility due to a seamless wide display area in the unfolded state.

[0301] The display panel 9311 is supported by three housings 9315 connected by a hinge 9313. Note that the display panel 9311 may be a touch panel (input / output device) equipped with a touch sensor (input device). Further, the display panel 9311 can be reversibly deformed from the unfolded state to the folded state of the mobile information terminal 9310 by bending between the two housings 9315 via the hinge 9313. The light-emitting device according to one aspect of the present invention can be used for the display panel 9311.

[0302] In addition, the organic compound which is one aspect of the present invention can be used in electronic devices such as organic thin film solar cells (OPV) and organic photodiodes (OPD). More specifically, since it has carrier transport properties, it can be used for carrier transport layers and carrier injection layers. Further, by using a mixed film with an acceptor substance, it can be used as a charge generation layer. Further, for photoexcitation, it can be used as a power generation layer or an active layer.

[0303] Note that the configuration shown in the present embodiment can be used by appropriately combining the configurations shown in Embodiments 1 to 4.

[0304] As described above, the application range of the light-emitting device including the light-emitting device described in Embodiment 2 is extremely wide, and this light-emitting device can be applied to electronic devices in all fields. By using the light-emitting device described in Embodiment 2, an electronic device with low power consumption can be obtained.

Example

[0305] ≪Synthesis Example 1≫ In this example, the synthesis method of 4-[3,6-bis(N,N-diphenylamino)carbazol-9-yl]benzofuro[3,2-d]pyrimidine (abbreviation: 4DPhA2CzBfpm), which is the organic compound shown as Structural Formula (100) in Embodiment 1, will be described in detail. The structural formula of 4DPhA2CzBfpm is shown below.

[0306]

Chemical formula

[0307] <Synthesis of 4-[3,6-bis(N,N-diphenylamino)carbazol-9-yl]benzofuro[3,2-d]pyrimidine (abbreviation: 4DPhA2CzBfpm)> After replacing the atmosphere in a 50 mL three-necked flask with nitrogen, 79 mg (2.0 mmol) of sodium hydride (NaH) and 15 mL of dehydrated N,N-dimethylformamide (abbreviation: DMF) were added, and the mixture was stirred at 0 °C. To this, 0.72 g (1.4 mmol) of 3,6-bis(N,N-diphenylamino)carbazole was added, and the mixture was stirred at 0 °C for 30 minutes. Then, 0.27 g (1.3 mmol) of 4-chlorobenzofuro[3,2-d]pyrimidine was added, and the mixture was stirred at room temperature for 18 hours. After a predetermined time had elapsed, water was poured into this mixture, and the precipitated solid was collected by suction filtration. The obtained solid was purified by silica gel column chromatography (developing solvent: toluene:ethyl acetate = 4:1), and further recrystallized from a mixed solvent of ethyl acetate and methanol, whereby 0.62 g (0.93 mmol) of a yellow solid of the target product was obtained in a yield of 71%. The synthetic scheme of this synthesis example is shown below.

[0308] [Chemical formula]

[0309] 0.61 g of the obtained yellow solid was purified by sublimation using the train sublimation method. The sublimation purification was carried out under the conditions of a pressure of 3.4 Pa, an argon flow rate of 5 mL / min, and a temperature of 290 °C. After sublimation purification, 0.55 g of yellow powder of 4DPhA2CzBfpm was obtained at a recovery rate of 84%.

[0310] The measurement results of the obtained compound by nuclear magnetic resonance spectroscopy ( 1 1H NMR) are shown in FIGS. 16A and 16B. Note that FIG. 16B is a graph showing an enlarged view of the range from 6.5 ppm to 9.5 ppm in FIG. 16A. The numerical data are shown below. 1 1H NMR (DMSO-d6, 300 MHz): δ = 6.92 - 7.03 (m, 12H), 7.20 - 7.29 (m, 10H), 7.61 - 7.68 (m, 1H), 7.81 - 7.93 (m, 4H), 8.02 (d, J = 2.2 Hz, 2H), 8.36 (d, J = 7.3 Hz, 1H), 9.29 (s, 1H).

[0311] Next, the results of measuring the absorption spectrum and emission spectrum of 4DPhA2CzBfpm in a toluene solution are shown in Fig. 17. The absorption spectrum was measured using an ultraviolet-visible spectrophotometer (Model V550 manufactured by JASCO Corporation), and is shown by subtracting the spectrum measured with only toluene in a quartz cell. Also, for the measurement of the emission spectrum, a fluorometer (FP-920 manufactured by JASCO Corporation) was used.

[0312] In addition, the absorption spectrum and fluorescence spectrum of 4DPhA2CzBfpm in the thin film state are shown in Fig. 18, and the phosphorescence spectrum is shown in Fig. 19. For the measurement of the absorption spectrum, a spectrophotometer (Spectrophotometer U4100 manufactured by Hitachi High-Technologies Corporation) was used. The solid thin film for absorption spectrum measurement was fabricated on a quartz substrate by vacuum evaporation. Also, for the measurement of the fluorescence spectrum and phosphorescence spectrum, a microscopic PL device LabRAM HR-PL (manufactured by Horiba, Ltd.) was used. The measurement temperature was 10 K, a He-Cd laser (325 nm) was used as the excitation light, and a CCD detector was used as the detector. The thin film of the sample was formed on a quartz substrate with a thickness of about 50 nm, and after attaching another quartz substrate from the vapor deposition surface side in a nitrogen atmosphere to this quartz substrate, it was used for measurement. Since the measurement of this emission spectrum was performed at a low temperature (10 K), in the measurement of a normal emission spectrum, in addition to fluorescence which is the main emission component, a part of phosphorescence was also observed. The spectrum obtained from the measurement of the time-resolved emission spectrum focusing on the emission with a long emission lifetime (integration from 20 ms to 120 ms after excitation light irradiation) was regarded mainly as phosphorescence.

[0313] As shown in Fig. 17, the toluene solution of 4DPhA2CzBfpm had an absorption peak at 394 nm, and the peak of the emission wavelength was 539 nm (excitation wavelength 394 nm). Also, as shown in Fig. 18, the thin film of 4DPhA2CzBfpm had absorption peaks at 401 nm, 363 nm, and 301 nm, and the peak of the fluorescence spectrum was found around 530 nm (excitation wavelength 325 nm). Further, as shown in Fig. 19, the peak on the shortest wavelength side in the phosphorescence spectrum of 4DPhA2CzBfpm was at 527 nm, indicating that it was a substance with a high T1 level. Note that the value of the peak read was shorter in wavelength for phosphorescence than for fluorescence, but the phosphorescence spectrum had a shape that was overall slightly shifted to longer wavelengths compared to the fluorescence spectrum. From these results, it was confirmed that 4DPhA2CzBfpm emits green light and was found to be usable as a light-emitting material, or as a host material for a fluorescent light-emitting material or a phosphorescent light-emitting material.

[0314] Note that the index of the T1 level can be calculated using the phosphorescence spectrum. By drawing a tangent at the trailing edge on the shorter wavelength side of the phosphorescence spectrum, the energy of the wavelength of the extrapolated line can be regarded as the T1 level. Also, the index of the S1 level can be calculated using the fluorescence spectrum. By drawing a tangent at the trailing edge on the shorter wavelength side of the fluorescence spectrum, the energy of the wavelength of the extrapolated line can be regarded as the S1 level.

[0315] The T1 level of 4DPhA2CzBfpm was calculated to be 2.49 eV from Fig. 19, and the S1 level was calculated to be 2.58 eV from Fig. 18. From this result, the difference ΔE ST between the T1 level and the S1 level of 4DPhA2CzBfpm was found to be 0.08 eV. Generally, it is said that ΔE ST of a material having TADF properties is preferably 0.2 eV or less, and it can be seen that ΔE ST of 4DPhA2CzBfpm is a sufficiently small value for it to have TADF properties.

Example

[0316] ≪Synthesis Example 2≫ In this synthesis example, the synthesis method of 8-phenyl-4-[3,6-bis(N,N-diphenylamino)carbazol-9-yl]benzofuro[3,2-d]pyrimidine (abbreviation: 8Ph-4DPhA2CzBfpm), which is the organic compound represented by structural formula (101) in Embodiment 1, will be described in detail. The structural formula of 8Ph-4DPhA2CzBfpm is shown below.

[0317] [Chemical formula]

[0318] [Synthesis of 8-phenyl-4-[3,6-bis(N,N-diphenylamino)carbazol-9-yl]benzofuro[3,2-d]pyrimidine (abbreviation: 8Ph-4DPhA2CzBfpm)] After purging the inside of a 100 mL three-necked flask with nitrogen, 130 mg (3.4 mmol) of sodium hydride (NaH) and 30 mL of dehydrated N,N-dimethylformamide (abbreviation: DMF) were added, and the mixture was stirred at 0°C. 1.2 g (2.5 mmol) of 3,6-bis(N,N-diphenylamino)carbazole was added thereto, and the mixture was stirred at 0°C for 30 minutes. Then, 0.63 g (2.2 mmol) of 4-chloro-8-phenylbenzofuro[3,2-d]pyrimidine was added, and the mixture was stirred at room temperature for 110 hours. After a predetermined time had elapsed, water was poured into the reaction mixture, and the precipitated solid was collected by suction filtration. The obtained solid was purified by silica gel column chromatography (developing solvent: toluene:ethyl acetate = 4:1), and further recrystallized from a mixed solvent of toluene and methanol, whereby 1.5 g of the target yellow solid was obtained in a yield of 91%. The synthesis scheme of this synthesis is shown below.

[0319] [Chemical formula]

[0320] 1.5 g of the obtained yellow solid was purified by sublimation using the train sublimation method. The sublimation purification was carried out under the conditions of a pressure of 3.1 Pa, an argon flow rate of 5 mL / min, and a temperature of 335 °C. After sublimation purification, 1.4 g of the yellow powder of 8Ph-4DPhA2CzBfpm was obtained with a recovery rate of 93%.

[0321] The measurement results of the obtained compound by nuclear magnetic resonance spectroscopy ( 1 1H NMR) are shown in FIGS. 20A and 20B. Note that FIG. 20B is a graph showing an enlarged view of the range from 6.5 ppm to 9.5 ppm in FIG. 20A. The numerical data are shown below. 1 1H NMR (CD2Cl2, 300 MHz): δ = 6.93 - 7.01 (m, 4H), 7.05 - 7.12 (m, 8H), 7.19 - 7.29 (m, 10H), 7.39 - 7.46 (m, 1H), 7.49 - 7.56 (m, 2H), 7.72 - 7.82 (m, 7H), 8.00 (dd, J = 1.8 Hz, 8.8 Hz, 1H), 8.53 (d, J = 2.2 Hz, 1H), 9.23 (s, 1H).

[0322] Next, the absorption spectrum and emission spectrum of 8Ph-4DPhA2CzBfpm in a toluene solution are shown in FIG. 21. The absorption spectrum was measured using an ultraviolet-visible spectrophotometer (V550 type manufactured by JASCO Corporation), and the spectrum measured with only toluene in a quartz cell was subtracted. For the measurement of the emission spectrum, a fluorescence photometer (FP-8600 manufactured by JASCO Corporation) was used.

[0323] In addition, the absorption spectrum and fluorescence spectrum of 8Ph-4DPhA2CzBfpm in the thin film state are shown in Fig. 22, and the phosphorescence spectrum is shown in Fig. 23. For the measurement of the absorption spectrum, a spectrophotometer (U4100, manufactured by Hitachi High-Technologies Corporation) was used. The solid thin film for absorption spectrum measurement was fabricated on a quartz substrate by vacuum evaporation. For the measurement of the fluorescence spectrum and phosphorescence spectrum of the thin film, a microscopic PL device LabRAM HR-PL (manufactured by Horiba, Ltd.) was used. The measurement temperature was 10 K, a He-Cd laser (325 nm) was used as the excitation light, and a CCD detector was used as the detector. The thin film of the sample was formed on a quartz substrate with a thickness of about 50 nm, and another quartz substrate was attached to the quartz substrate from the vapor deposition surface side in a nitrogen atmosphere and then used for measurement. Since the measurement of this emission spectrum was performed at a low temperature (10 K), in the measurement of the normal emission spectrum, in addition to fluorescence which is the main emission component, a part of phosphorescence was also observed. The spectrum obtained from the measurement of the time-resolved emission spectrum (integrating from 20 ms to 120 ms after excitation light irradiation) focusing on the emission with a long emission lifetime was mainly regarded as phosphorescence.

[0324] As shown in Fig. 21, the toluene solution of 8Ph-4DPhA2CzBfpm had absorption peaks at 397 nm and 360 nm, and the peak of the emission wavelength was 545 nm (excitation wavelength 397 nm). Also, as shown in Fig. 22, the thin film of 8Ph-4DPhA2CzBfpm had absorption peaks at 410 nm, 363 nm, and 301 nm, and the peak of the fluorescence spectrum was observed at 530 nm (near the excitation wavelength 325 nm). Further, as shown in Fig. 23, the peak on the shortest wavelength side in the phosphorescence spectrum of 8Ph-4DPhA2CzBfpm was found to be at 531 nm, indicating that it is a substance with a high T1 level. The value of the peak read was such that the phosphorescence had a shorter wavelength than the fluorescence, but the phosphorescence spectrum had a shape that was slightly shifted to a longer wavelength overall than the fluorescence spectrum. From these results, it was confirmed that 8Ph-4DPhA2CzBfpm emits green light and was found to be usable as a light-emitting material, or as a host material for a fluorescent light-emitting material or a phosphorescent light-emitting material.

[0325] Note that the index of the T1 level can be calculated using the phosphorescence spectrum. A tangent is drawn at the trailing edge on the short-wavelength side of the phosphorescence spectrum, and the energy of the wavelength of the extrapolated line can be regarded as the T1 level. Also, the index of the S1 level can be calculated using the fluorescence spectrum. A tangent is drawn at the trailing edge on the short-wavelength side of the fluorescence spectrum, and the energy of the wavelength of the extrapolated line can be regarded as the S1 level.

[0326] The T1 level of 8Ph-4DPhA2CzBfpm was calculated to be 2.48 eV from Fig. 23, and the S1 level was calculated to be 2.56 eV from Fig. 22. From this result, ΔE ST which is the difference between the T1 level and the S1 level of 8Ph-4DPhA2CzBfpm ST was found to be 0.08 eV. Generally, it is said that ΔE ST of materials having TADF properties is preferably 0.2 eV or less, and it can be seen that ΔE

Example

[0327] ≪Synthesis Example 3≫ In this synthesis example, the synthesis method of 4-[3-(N,N-diphenylamino)carbazol-9-yl]benzofuro[3,2-d]pyrimidine (abbreviation: 4DPhACzBfpm) shown as structural formula (102) in Embodiment 1 will be described in detail. The structural formula of 4DPhACzBfpm is shown below.

[0328]

Chemical formula

[0329] <Synthesis of 4-[3-(N,N-diphenylamino)carbazol-9-yl]benzofuro[3,2-d]pyrimidine (abbreviation: 4DPhACzBfpm)> After replacing the atmosphere in a 50 mL three-necked flask with nitrogen, 82 mg (2.0 mmol) of sodium hydride (NaH) and 15 mL of dehydrated N,N-dimethylformamide (abbreviation: DMF) were added, and the mixture was stirred at 0 °C. To this, 0.50 g (1.5 mmol) of 3-(N,N-diphenylamino)carbazole was added, and the mixture was stirred at 0 °C for 30 minutes. Then, 0.28 g (1.4 mmol) of 4-chlorobenzofuro[3,2-d]pyrimidine was added, and the mixture was stirred at room temperature for 18 hours. After a predetermined time had elapsed, water was poured into this mixture, and the precipitated solid was collected by suction filtration. The obtained solid was purified by silica gel column chromatography (developing solvent: toluene:ethyl acetate = 4:1) to obtain 0.76 g of the target yellow solid. The obtained solid was irradiated with ultrasonic waves in a methanol suspension, and the solid was collected by suction filtration to obtain 0.50 g (0.99 mmol) of the target yellow solid in a yield of 73%. The synthetic scheme for this synthesis is shown below.

[0330]

Chemical formula

[0331] 0.49 g of the obtained yellow solid was purified by sublimation using the train sublimation method. The sublimation purification was carried out under the conditions of a pressure of 3.4 Pa, an argon flow rate of 5 mL / min, and a temperature of 235 °C. After sublimation purification, 0.36 g of the yellow powder of 4DPhACzBfpm was obtained at a recovery rate of 74%.

[0332] The measurement results of the obtained compound by nuclear magnetic resonance spectroscopy ( 1 1H-NMR) are shown in FIGS. 24A and 24B. Note that FIG. 24B is a graph showing an enlarged view of the range from 6.5 ppm to 9.5 ppm in FIG. 24A. The numerical data are shown below. 1 1H NMR (DMSO-d6, 300 MHz): δ = 6.97 - 7.08 (m, 6H), 7.21 - 7.40 (m, 6H), 7.46 - 7.54 (m, 1H), 7.61 - 7.68 (m, 1H), 7.80 - 7.93 (m, 4H), 8.07 (d, J = 1.8 Hz, 1H), 8.24 (d, J = 7.3 Hz, 1H), 8.37 (d, J = 7.3 Hz, 1H), 9.31 (s, 1H).

[0333] Next, the results of measuring the absorption spectrum and emission spectrum of 4DPhACzBfpm in a toluene solution are shown in Fig. 25. The absorption spectrum was measured using an ultraviolet-visible spectrophotometer (V550 type manufactured by JASCO Corporation), and the spectrum measured with only toluene in a quartz cell was subtracted. Also, a fluorometer (FP-920 manufactured by JASCO Corporation) was used to measure the emission spectrum.

[0334] Also, the absorption spectrum and fluorescence spectrum of 4DPhACzBfpm in the thin film state are shown in Fig. 26, and the phosphorescence spectrum is shown in Fig. 27. A spectrophotometer (Spectrophotometer U4100 manufactured by Hitachi High-Technologies Corporation) was used to measure the absorption spectrum. The solid thin film for absorption spectrum measurement was fabricated on a quartz substrate by vacuum evaporation. Also, a microscopic PL apparatus LabRAM HR-PL (manufactured by Horiba, Ltd.) was used to measure the fluorescence spectrum and phosphorescence spectrum. The measurement temperature was 10 K, a He-Cd laser (325 nm) was used as the excitation light, and a CCD detector was used as the detector. The thin film of the sample was formed on a quartz substrate with a thickness of about 50 nm, and another quartz substrate was attached to the quartz substrate from the vapor deposition surface side in a nitrogen atmosphere and then used for measurement. Note that since the measurement of this emission spectrum was performed at a low temperature (10 K), in addition to fluorescence, which is the main emission component, a part of phosphorescence was also observed in the measurement of the normal emission spectrum. The spectrum obtained from the measurement of the time-resolved emission spectrum (integration from 20 ms to 120 ms after excitation light irradiation), focusing on the emission with a long emission lifetime, was regarded mainly as phosphorescence.

[0335] As shown in Figure 25, the toluene solution of 4DPhACzBfpm showed an absorption peak at 375 nm, and the peak of the emission wavelength was 532 nm (excitation wavelength 375 nm). Also, as shown in Figure 26, the thin film of 4DPhACzBfpm showed absorption peaks at 379 nm and 293 nm, and the peak of the fluorescence spectrum was found around 525 nm (excitation wavelength 325 nm). Further, as shown in Figure 27, the peak on the shortest wavelength side in the phosphorescence spectrum of 4DPhACzBfpm was found at 521 nm, indicating that it is a substance with a high T1 level. Note that the value of the peak read was such that the phosphorescence had a shorter wavelength than the fluorescence, but the phosphorescence spectrum had a shape that was slightly shifted to a longer wavelength overall compared to the fluorescence spectrum. From these results, it was confirmed that 4DPhACzBfpm emits green light, and it was found that it can be used as a luminescent material, or as a host material for a fluorescent luminescent material or a phosphorescent luminescent substance.

[0336] Note that the index of the T1 level can be calculated using the phosphorescence spectrum. By drawing a tangent line at the trailing edge on the short wavelength side of the phosphorescence spectrum, the energy of the wavelength of the extrapolated line can be regarded as the T1 level. Also, the index of the S1 level can be calculated using the fluorescence spectrum. By drawing a tangent line at the trailing edge on the short wavelength side of the fluorescence spectrum, the energy of the wavelength of the extrapolated line can be regarded as the S1 level.

[0337] The T1 level of 4DPhACzBfpm was calculated to be 2.56 eV from Figure 27, and the S1 level was calculated to be 2.64 eV from Figure 26. From this result, ΔE ST which is the difference between the T1 level and the S1 level of 4DPhACzBfpm ST was found to be 0.08 eV. Generally, it is said that ΔE ST of a material having TADF properties is preferably 0.2 eV or less, and it can be seen that ΔE

Example

[0338] In this example, the distributions of the lowest unoccupied molecular orbital (LUMO) levels and the highest occupied molecular orbital (HOMO) levels of the organic compounds represented by the following structural formulas (100) to (104), which are organic compounds of one aspect of the present invention, were verified using molecular orbital calculations.

[0339]

Chemical formula

[0340] The calculations were performed using the density functional theory (DFT) for the most stable structure in the singlet ground state. At this time, vibrational analysis was performed for each of the most stable structures. As the basis function, 6-311G was applied to all atoms. Furthermore, in order to improve the calculation accuracy, as a polarized basis set, a p function was added to hydrogen atoms and a d function was added to atoms other than hydrogen atoms. The functional B3LYP was used. In addition, the HOMO level and the LUMO level were calculated for the calculated singlet most stable structure, respectively. In DFT, the total energy of a molecule is represented by the sum of the potential energy, the electrostatic energy between electrons, the kinetic energy of electrons, and the exchange-correlation energy that includes all complex interactions between electrons. Also, in DFT, since the exchange-correlation interaction is approximated by a functional of the one-electron potential represented by the electron density (the meaning of a function of a function), the electronic state can be obtained with higher accuracy.

[0341] Note that Gaussian 09 was used as the quantum chemistry calculation program. The calculations were performed using a high-performance computer (manufactured by SGI, Altix4700).

[0342] The results are shown in FIGS. 28 and 29. As shown in FIGS. 28 and 29, it was found that in the above five substances, which are organic compounds of one aspect of the present invention, the LUMO levels are mainly spatially separated in the benzofuropyrimidine skeleton, and the HOMO levels are spatially separated in the carbazole skeleton and the diphenylamine skeleton, respectively.

[0343] In addition, for the organic compounds represented by Structural Formulas (103) and (104) in which a carbazole skeleton is bonded to a benzofuropyrimidine skeleton via a phenylene group, ΔE ST is smaller than that of the organic compound represented by Structural Formula (100) not having a phenylene group (0.09 eV, 0.02 eV, 0.18 eV (calculated values) in order). Further, for Structural Formula (104) in which this phenylene group is substituted at the meta position, ΔE ST is smaller than that of Structural Formula (103) at the para position. Note that these ΔE ST were obtained by calculating the singlet lowest excitation energy (S1) and the triplet lowest excitation energy (T1) by the time-dependent density functional theory (TD-DFT) using the most stable structure of the singlet ground state, and finding the difference therebetween. The basis function 6-311G(d,p) and the functional B3LYP were used.

[0344] In order to cause TADF, it is necessary to preferentially cause reverse intersystem crossing from T1 to S1 and make it faster than the non-radiative deactivation rate from T1 to S0. For this, it is effective to reduce the energy difference ΔE ST between S1 and T1 states. In order to reduce ΔE ST , it is sufficient to reduce the overlap density of HOMO and LUMO, and it is said that a molecular design that spatially separates HOMO and LUMO is effective.

[0345] It can be said that the above five substances, which are organic compounds of one aspect of the present invention, are exactly organic compounds having such a molecular structure. In particular, for the organic compounds represented by Structural Formulas (100) to (102) synthesized in Examples 1 to 3, the actually measured ΔE ST was also as small as 0.08 eV, and it was found that they are organic compounds with high TADF properties.

Example

[0346] In this example, a light-emitting device 1 using an organic compound of one aspect of the present invention will be described. The structural formulas of the organic compounds used in the light-emitting device 1 are shown below.

[0347] [Chemical formula]

[0348] (Method for fabricating a light-emitting device 1) First, indium tin oxide (ITSO) containing silicon oxide was deposited on a glass substrate by sputtering to form a first electrode 101. The film thickness was 70 nm, and the electrode area was 2 mm × 2 mm.

[0349] Next, as a pretreatment for forming a light-emitting device on the substrate, the substrate surface was washed with water, baked at 200 °C for 1 hour, and then subjected to UV ozone treatment for 370 seconds.

[0350] After that, the substrate was introduced into a vacuum evaporation apparatus whose internal pressure was reduced to about 10 -4 Pa, and vacuum baking was performed at 170 °C for 30 minutes in the heating chamber of the vacuum evaporation apparatus. Then, the substrate was allowed to cool for about 30 minutes.

[0351] Next, with the surface on which the first electrode 101 was formed facing downward, the substrate on which the first electrode 101 was formed was fixed to a substrate holder provided in the vacuum evaporation apparatus. On the first electrode 101, 4,4’,4’’-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) represented by the above structural formula (i) and molybdenum(VI) oxide were co-evaporated at a weight ratio of 1:0.5 (= DBT3P-II: molybdenum(VI) oxide) to a thickness of 40 nm to form a hole injection layer 111.

[0352] Next, 9-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]9H-carbazole (abbreviation: mCzFLP) represented by the above structural formula (ii) was deposited on the hole injection layer 111 to a thickness of 20 nm to form a hole transport layer 112.

[0353] Subsequently, 9,9’-(pyrimidine-4,6-diyl-di-3,1-phenylene)bis(9H-carbazole) (abbreviation: 4,6mCzP2Pm) represented by the above structural formula (iii) and 4-[3,6-bis(N,N-diphenylamino)carbazol-9-yl]benzofuro[3,2-d]pyrimidine (abbreviation: 4DPhA2CzBfpm) represented by the above structural formula (100) were co-evaporated at a weight ratio of 1:0.1 (= 4,6mCzP2Pm:4DPhA2CzBfpm) to a thickness of 30 nm to form the light-emitting layer 113.

[0354] Thereafter, 4,6mCzP2Pm was formed on the light-emitting layer 113 to a thickness of 20 nm, and further 2,9-di(2-naphthyl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBPhen) represented by the above structural formula (iv) was evaporated to a thickness of 15 nm to form the electron transport layer 114.

[0355] After forming the electron transport layer 114, lithium fluoride (LiF) was evaporated to a thickness of 1 nm to form the electron injection layer 115, and then aluminum was evaporated to a thickness of 200 nm to form the second electrode 102, thereby fabricating the light-emitting device 1 of this example.

[0356] The device structure of the above light-emitting device is summarized in the following table.

[0357]

Table 1

[0358] After the above light-emitting device was sealed with a glass substrate in a glove box under a nitrogen atmosphere so that the light-emitting device was not exposed to the atmosphere (a sealing material was applied around the device, and UV treatment and heat treatment were performed at 80 °C for 1 hour during sealing), the initial characteristics were measured.

[0359] The luminance-current density characteristics of the light-emitting device 1 are shown in FIG. 30, the current efficiency-luminance characteristics are shown in FIG. 31, the luminance-voltage characteristics are shown in FIG. 32, the current-voltage characteristics are shown in FIG. 33, the external quantum efficiency-luminance characteristics are shown in FIG. 34, and the emission spectrum is shown in FIG. 35. Also, the main characteristics of the light-emitting device 1 near 1000 cd / m 2 are shown below.

[0360]

Table 2

[0361] From FIGS. 30 to 34, it was found that the light-emitting device 1 of one aspect of the present invention is a highly efficient light-emitting element having good characteristics, with an external quantum efficiency of up to 25% or more at maximum. This is a value that greatly exceeds the theoretical limit of fluorescence emission in current excitation, suggesting that energy from triplet excitons contributes to the emission.

[0362] In the light-emitting device 1, 4DPhA2CzBfpm used as the light-emitting material exists in a state where the HOMO and LUMO are spatially separated within the molecule, as shown in Example 4, and as measured in Example 1, ΔE ST is a small organic compound. From this, it is known that 4DPhA2CzBfpm is a substance that easily exhibits TADF.

[0363] Therefore, the results of measuring the transient EL characteristics of the light-emitting device 1 are shown in FIGS. 36A and 36B. A picosecond fluorescence lifetime measurement system (manufactured by Hamamatsu Photonics) was used for the measurement. In this measurement, a rectangular pulse voltage was applied to the light-emitting device, and the emission that decayed from the fall of the voltage was measured by time-resolved measurement using a streak camera. The measurement was performed at room temperature (25°C).

[0364] In FIGS. 36A and 36B, the vertical axis represents the intensity normalized by the emission intensity in a state where carriers are constantly injected (when the pulse voltage is on). The horizontal axis represents the elapsed time from the fall of the pulse voltage. Note that FIGS. 36A and 36B have different time ranges for the measurement.

[0365] From the transient EL characteristics shown in FIGS. 36A and 36B, at least a light-emitting component with a fast decay and a fluorescence lifetime (transient lifetime) of about 0.4 μs and a slow light-emitting component with a fluorescence lifetime of about 9 μs were observed from the light-emitting device 1. Among these, the light-emitting component with a fluorescence lifetime of 9 μs is delayed fluorescence based on reverse intersystem crossing, and it was found that the light-emitting device 1 exhibits TADF. Further, as a result, it was found that the light-emitting device 1 emits light with very good luminous efficiency as a result of TADF being expressed by using 4DPhA2CzBfpm as a light-emitting material and triplet excitons being involved in light emission.

Example

[0366] In this example, a light-emitting device 2 using an organic compound according to one aspect of the present invention will be described. The structural formula of the organic compound used in the light-emitting device 2 is shown below.

[0367]

Chemical formula

[0368] (Method for manufacturing the light-emitting device 2) First, indium tin oxide (ITSO) containing silicon oxide was formed into a film on a glass substrate by a sputtering method to form a first electrode 101. The film thickness was 70 nm, and the electrode area was 2 mm × 2 mm.

[0369] Next, as a pretreatment for forming a light-emitting device on the substrate, the substrate surface was washed with water, baked at 200° C. for 1 hour, and then subjected to UV ozone treatment for 370 seconds.

[0370] After that, the substrate was introduced into a vacuum deposition apparatus whose internal pressure was reduced to about 10 -4 Pa, and in the heating chamber of the vacuum deposition apparatus, vacuum baking was performed at 170° C. for 30 minutes, and then the substrate was allowed to cool for about 30 minutes.

[0371] Next, the substrate on which the first electrode 101 is formed is fixed to a substrate holder provided in a vacuum deposition apparatus so that the surface on which the first electrode 101 is formed faces downward. Onto the first electrode 101, 4,4’,4’’-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) represented by the above structural formula (i) and molybdenum(VI) oxide are co-deposited at 40 nm so that the weight ratio is 1:0.5 (= DBT3P-II: molybdenum(VI) oxide) by a vapor deposition method using resistance heating to form a hole injection layer 111.

[0372] Next, 9-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]9H-carbazole (abbreviation: mCzFLP) represented by the above structural formula (ii) is deposited to a thickness of 20 nm onto the hole injection layer 111 to form a hole transport layer 112.

[0373] Subsequently, 2-(9,9’-spirobi[fluorene]-3-yl)-4,6-diphenyl-1,3,5-triazine (abbreviation: SF3-TZN) represented by the above structural formula (v) and 8-phenyl-4-[3,6-bis(N,N-diphenylamino)carbazol-9-yl]benzofuro[3,2-d]pyrimidine (abbreviation: 8Ph-4DPhA2CzBfpm) represented by the above structural formula (101) are co-deposited at 30 nm so that the weight ratio is 1:0.1 (= SF3-TZN: 8Ph-4DPhA2CzBfpm) to form a light-emitting layer 113.

[0374] Thereafter, 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm) represented by the above structural formula (iii) is formed to a film thickness of 20 nm onto the light-emitting layer 113, and further 2,9-di(2-naphthyl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBPhen) represented by the above structural formula (iv) is deposited to a film thickness of 15 nm to form an electron transport layer 114.

[0375] After forming the electron transport layer 114, lithium fluoride (LiF) was deposited at a thickness of 1 nm to form the electron injection layer 115, and then aluminum was deposited to a film thickness of 200 nm to form the second electrode 102, thereby fabricating the light-emitting device 2 of this example.

[0376] The element structure of the above light-emitting device is summarized in the following table.

[0377]

Table 3

[0378] After the above light-emitting device was sealed with a glass substrate in a glove box under a nitrogen atmosphere so that the light-emitting device was not exposed to the atmosphere (a sealing material was applied around the element, and UV treatment and heat treatment were performed at 80 °C for 1 hour during sealing), the initial characteristics were measured.

[0379] The luminance-current density characteristics of the light-emitting device 2 are shown in FIG. 37, the current efficiency-luminance characteristics are shown in FIG. 38, the luminance-voltage characteristics are shown in FIG. 39, the current-voltage characteristics are shown in FIG. 40, the external quantum efficiency-luminance characteristics are shown in FIG. 41, and the emission spectrum is shown in FIG. 42. Also, the main characteristics of the light-emitting device 2 near 1000 cd / m 2 are shown below.

[0380]

Table 4

[0381] From FIGS. 37 to 41, it was found that the light-emitting device 2 of one aspect of the present invention is a highly efficient light-emitting element having good characteristics with a maximum external quantum efficiency of 25% or more. This is a value that greatly exceeds the theoretical limit of fluorescence emission in current excitation, suggesting that energy from triplet excitons contributes to the emission.

[0382] In the light-emitting device 2, 8Ph-4DPhA2CzBfpm used as a light-emitting material, as shown in Example 4, has its HOMO and LUMO spatially separated within the molecule. As measured in Example 2, ΔE ST is a small organic compound with an easy occurrence of reverse intersystem crossing. From these facts, 8Ph-4DPhA2CzBfpm is a substance that easily exhibits TADF. As a result of using 8Ph-4DPhA2CzBfpm as a light-emitting material in the light-emitting device 2, TADF is expressed, and triplet excitons are involved in light emission, so it is considered that the light-emitting device emits light with very good luminous efficiency.

Example

[0383] In this example, a light-emitting device 3 using an organic compound according to one aspect of the present invention will be described. The structural formula of the organic compound used in the light-emitting device 3 is shown below.

[0384]

Chemical formula

[0385] (Method for manufacturing the light-emitting device 3) First, indium tin oxide (ITSO) containing silicon oxide was formed into a film on a glass substrate by a sputtering method to form a first electrode 101. The film thickness was set to 70 nm, and the electrode area was set to 2 mm × 2 mm.

[0386] Next, as a pretreatment for forming a light-emitting device on the substrate, the substrate surface was washed with water, baked at 200 °C for 1 hour, and then subjected to UV ozone treatment for 370 seconds.

[0387] Thereafter, the substrate was introduced into a vacuum evaporation apparatus whose interior was evacuated to about 10 -4 Pa, and in the heating chamber of the vacuum evaporation apparatus, vacuum baking was performed at 170 °C for 30 minutes, and then the substrate was allowed to cool for about 30 minutes.

[0388] Next, with the surface on which the first electrode 101 is formed facing downward, the substrate on which the first electrode 101 is formed is fixed to a substrate holder provided in a vacuum deposition apparatus, and on the first electrode 101, 4,4’,4’’-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) represented by the above structural formula (i) and molybdenum(VI) oxide are co-evaporated at 40 nm so that the weight ratio is 1:0.5 (= DBT3P-II: molybdenum(VI) oxide) to form a hole injection layer 111 by a deposition method using resistance heating.

[0389] Next, 9-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]9H-carbazole (abbreviation: mCzFLP) represented by the above structural formula (ii) is deposited to a thickness of 20 nm on the hole injection layer 111 to form a hole transport layer 112.

[0390] Subsequently, 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm) represented by the above structural formula (iii) and 4-[3-(N,N-diphenylamino)carbazol-9-yl]benzofuro[3,2-d]pyrimidine (abbreviation: 4DPhACzBfpm) represented by the above structural formula (102) are co-evaporated at 30 nm so that the weight ratio is 1:0.1 (= 4,6mCzP2Pm: 4DPhACzBfpm) to form a light-emitting layer 113.

[0391] Thereafter, 4,6mCzP2Pm is formed on the light-emitting layer 113 to a film thickness of 20 nm, and further 2,9-di(2-naphthyl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBPhen) represented by the above structural formula (iv) is deposited to a film thickness of 15 nm to form an electron transport layer 114.

[0392] After forming the electron transport layer 114, lithium fluoride (LiF) is deposited at 1 nm to form an electron injection layer 115, and then aluminum is deposited to a film thickness of 200 nm to form a second electrode 102, thereby fabricating the light-emitting device 3 of this example.

[0393] The element structure of the above light-emitting device is summarized in the following table.

[0394]

Table 5

[0395] After performing the operation of sealing the above light-emitting device with a glass substrate in a nitrogen atmosphere glove box so that the light-emitting device is not exposed to the atmosphere (applying a sealing material around the element and performing UV treatment and heat treatment at 80°C for 1 hour during sealing), the initial characteristics were measured.

[0396] The luminance-current density characteristics of Light-Emitting Device 3 are shown in FIG. 43, the current efficiency-luminance characteristics are shown in FIG. 44, the luminance-voltage characteristics are shown in FIG. 45, the current-voltage characteristics are shown in FIG. 46, the external quantum efficiency-luminance characteristics are shown in FIG. 47, and the emission spectrum is shown in FIG. 48. Also, the main characteristics of Light-Emitting Device 3 near 1000 cd / m 2 are shown below.

[0397]

Table 6

[0398] From FIGS. 43 to 47, it was found that the light-emitting device 3 of one aspect of the present invention is a highly efficient light-emitting element having good characteristics with an external quantum efficiency of up to 20% or more. This is a value that greatly exceeds the theoretical limit of fluorescence emission in current excitation, suggesting that energy from triplet excitons contributes to the emission.

[0399] In Light-Emitting Device 3, 4DPhACzBfpm used as the light-emitting material, as shown in Example 4, has HOMO and LUMO existing in a spatially separated state within the molecule, and as measured in Example 3, ΔE ST is a small organic compound. From this, it is known that 4DPhACzBfpm is a substance that easily exhibits TADF.

[0400] Therefore, the results of measuring the transient EL characteristics of the light-emitting device 3 are shown in FIGS. 49A and 49B. A picosecond fluorescence lifetime measurement system (manufactured by Hamamatsu Photonics) was used for the measurement. In this measurement, a rectangular pulse voltage was applied to the light-emitting device, and the light emission that decayed from the fall of the voltage was measured by time-resolved measurement using a streak camera. The measurement was performed at room temperature (25°C).

[0401] In FIGS. 49A and 49B, the vertical axis represents the intensity normalized by the emission intensity in a state where carriers are constantly injected (when the pulse voltage is on). The horizontal axis represents the elapsed time from the fall of the pulse voltage. Note that FIGS. 49A and 49B have different time ranges for the measurement.

[0402] From the transient EL characteristics shown in FIGS. 49A and 49B, at least a light-emitting component with a fast decay of about 0.3 μs in fluorescence lifetime (transient lifetime) and a slow light-emitting component of about 10 μs were observed from the light-emitting device 3. Among these, the light-emitting component with a fluorescence lifetime of 10 μs is delayed fluorescence based on reverse intersystem crossing, and it was found that the light-emitting device 3 exhibits TADF. Also, thereby, it was found that the light-emitting device 3 emits TADF by using 4DPhACzBfpm as a light-emitting material, and as a result of triplet excitons being involved in light emission, it has become a light-emitting device that emits light with very good luminous efficiency.

Example

[0403] In this example, a light-emitting device 4 using an organic compound according to one aspect of the present invention will be described. The structural formula of the organic compound used in the light-emitting device 4 is shown below.

[0404]

Chemical formula

[0405] (Method for manufacturing the light-emitting device 4) First, indium tin oxide (ITSO) containing silicon oxide was formed into a film on a glass substrate by a sputtering method to form a first electrode 101. The film thickness was 70 nm, and the electrode area was 2 mm × 2 mm.

[0406] Next, as a pretreatment for forming a light-emitting device on a substrate, the substrate surface was washed with water, baked at 200°C for 1 hour, and then subjected to UV ozone treatment for 370 seconds.

[0407] Then, 10 -4 The substrate was introduced into a vacuum evaporation apparatus whose internal pressure was reduced to about 10 Pa. In the heating chamber of the vacuum evaporation apparatus, vacuum baking was performed at 170°C for 30 minutes, and then the substrate was allowed to cool for about 30 minutes.

[0408] Next, the substrate on which the first electrode 101 was formed was fixed to a substrate holder provided in the vacuum evaporation apparatus so that the surface on which the first electrode 101 was formed faced downward. On the first electrode 101, 4,4’,4’’-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) represented by the above structural formula (i) and molybdenum(VI) oxide were co-evaporated at a weight ratio of 1:0.5 (= DBT3P-II: molybdenum(VI) oxide) to form a hole injection layer 111.

[0409] Next, 9-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]9H-carbazole (abbreviation: mCzFLP) represented by the above structural formula (ii) was evaporated to a thickness of 20 nm on the hole injection layer 111 to form a hole transport layer 112.

[0410] Subsequently, 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm) represented by the above structural formula (iii), 4-[3,6-bis(N,N-diphenylamino)carbazol-9-yl]benzofuro[3,2-d]pyrimidine (abbreviation: 4DPhA2CzBfpm) represented by the above structural formula (100), and 2,8-di-tert-butyl-5,11-bis(4-tert-butylphenyl)-6,12-diphenyltetracene (abbreviation: TBRb) were co-evaporated at a weight ratio of 1:1:0.01 (= 4,6mCzP2Pm:4DPhA2CzBfpm:TBRb) to form a light-emitting layer 113.

[0411] Thereafter, 4,6mCzP2Pm was formed on the light-emitting layer 113 to a film thickness of 20 nm, and further, 2,9-di(2-naphthyl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBPhen) represented by the above structural formula (iv) was vapor-deposited to a film thickness of 15 nm to form the electron transport layer 114.

[0412] After forming the electron transport layer 114, lithium fluoride (LiF) was vapor-deposited at 1 nm to form the electron injection layer 115, and subsequently, aluminum was vapor-deposited to a film thickness of 200 nm to form the second electrode 102, thereby fabricating the light-emitting device 4 of this example.

[0413] The element structure of the above light-emitting device is summarized in the following table.

[0414]

Table 7

[0415] After the above light-emitting device was sealed with a glass substrate in a glove box under a nitrogen atmosphere so that the light-emitting device was not exposed to the atmosphere (a sealing material was applied around the element, and UV treatment and heat treatment were performed at 80 °C for 1 hour during sealing), the initial characteristics were measured.

[0416] The luminance-current density characteristics of the light-emitting device 4 are shown in FIG. 50, the current efficiency-luminance characteristics are shown in FIG. 51, the luminance-voltage characteristics are shown in FIG. 52, the current-voltage characteristics are shown in FIG. 53, the external quantum efficiency-luminance characteristics are shown in FIG. 54, and the emission spectrum is shown in FIG. 55. Also, the main characteristics of the light-emitting device 4 near 1000 cd / m 2 are shown below.

[0417]

Table 8

[0418] From FIG. 55 and the chromaticity, it can be seen that the light-emitting device 4 emits light from TBRb. Also, from FIGS. 50 to 54, it was found that the light-emitting device 4 of one aspect of the present invention is a highly efficient light-emitting element having good characteristics, showing an external quantum efficiency of 20% or more. This is a value that greatly exceeds the theoretical limit of fluorescence emission in current excitation, suggesting that energy from triplet excitons contributes to the emission.

[0419] In the light-emitting device 4, 4DPhA2CzBfpm used as one of the host materials exists in a state where the HOMO and LUMO are spatially separated within the molecule, as shown in Example 4, and as measured in Example 1, ΔE ST is a small organic compound. From this, it is known that 4DPhACzBfpm is a substance that easily undergoes reverse intersystem crossing.

[0420] Therefore, the results of measuring the transient EL characteristics of the light-emitting device 4 are shown in FIG. 56. A picosecond fluorescence lifetime measurement system (manufactured by Hamamatsu Photonics) was used for the measurement. In this measurement, a rectangular pulse voltage was applied to the light-emitting device, and the emission that decayed from the fall of the voltage was time-resolvedly measured with a streak camera. The measurement was performed at room temperature (25 °C).

[0421] In FIGS. 56A and 56B, the vertical axis represents the intensity normalized by the emission intensity in a state where carriers are constantly injected (when the pulse voltage is on). The horizontal axis represents the elapsed time from the fall of the pulse voltage. Note that FIGS. 56A and 56B have different measurement time ranges.

[0422] From the transient EL characteristics shown in FIGS. 56A and 56B, at least an emission component with a fast decay with a fluorescence lifetime (transient lifetime) of about 0.2 μs and a slow emission component with a fluorescence lifetime of about 8 μs were observed from the light-emitting device 4. Among these, the emission component with a fluorescence lifetime of 8 μs is delayed fluorescence.

[0423] TBRb is a fluorescent substance and does not have TADF properties. From this, in the light-emitting device 4, the singlet excited state is generated by the reverse intersystem crossing of the triplet excited state of 4DPhA2CzBfpm to the singlet excited state, and energy transfer occurs from this singlet excited state to TBRb, causing TBRb to emit light. It is a so-called exciton-trapping type fluorescent element, and it has been found that high efficiency is achieved.

Explanation of symbols

[0424] 101: First electrode, 102: Second electrode, 103: EL layer, 111: Hole injection layer, 112: Hole transport layer, 113: Light-emitting layer, 114: Electron transport layer, 115: Electron injection layer, 116: Charge generation layer, 117: P-type layer, 118: Electron relay layer, 119: Electron injection buffer layer, 400: Substrate, 401: First electrode, 403: EL layer, 404: Second electrode, 405: Sealing material, 406: Sealing material, 407: Sealing substrate, 412: Pad, 420: IC chip, 501: Anode, 502: Cathode, 511: First light-emitting unit, 512: Second light-emitting unit, 513: Charge generation layer, 601: Driving circuit section (source line driving circuit), 602: Pixel section, 603: Driving circuit section (gate line driving circuit), 604: Sealing substrate, 605: Sealing material, 607: Space, 608: Wiring, 609: FPC (Flexible Printed Circuit), 610: Element substrate, 611: Switching FET, 612: Current control FET, 613: First electrode, 614: Insulator, 616: EL layer, 617: Second electrode, 618: Light-emitting device, 730: Insulating film, 770: Planarizing insulating film, 772: Conductive film, 782: Light-emitting device, 783: Droplet ejection device, 784: Droplet, 785: Layer, 786: EL layer, 788: Conductive film, 951: Substrate, 952: Electrode, 953: Insulating layer, 954: Partition layer, 955: EL layer, 956: Electrode, 1001: Substrate, 1002: Underlying insulating film, 1003: Gate insulating film, 1006: Gate electrode, 1007: Gate electrode, 1008: Gate electrode, 1020: First interlayer insulating film, 1021: Second interlayer insulating film, 1022: Electrode, 1024W: First electrode, 1024R: First electrode, 1024G: First electrode, 1024B: First electrode, 1025: Partition, 1028: EL layer, 1029: Second electrode, 1031: Sealing substrate, 1032: Sealing material, 1033: Transparent base material, 1034R: Red coloring layer, 1034G: Green coloring layer, 1034B: Blue coloring layer, 1035: Black matrix, 1036: Overcoat layer, 1037: Third interlayer insulating film, 1040: Pixel section, 1041: Driving circuit section, 1042: Peripheral section, 1400: Droplet ejection device, 1402: Substrate, 1403: Droplet ejection means, 1404: Imaging means, 1405: Head, 1406: Dotted line, 1407: Control means, 1408: Storage medium, 1409: Image processing means, 1410: Computer, 1411: Marker,1412: Head, 1413: Material supply source, 1414: Material supply source, 1415: Material supply source, 1416: Head, 2001: Housing, 2002: Light source, 2100: Robot, 2110: Computing device, 2101: Illuminance sensor, 2102: Microphone, 2103: Upper camera, 2104: Speaker, 2105: Display, 2106: Lower camera, 2107: Obstacle sensor, 2108: Moving mechanism, 3001: Lighting device, 5000: Housing, 5001: Display unit, 5002: Display unit, 5003: Speaker, 5004: LED lamp, 5006: Connection terminal, 5007: Sensor, 5008: Microphone, 5012: Support part, 5013: Earphone, 5100: Cleaning robot, 5101: Display, 5102: Camera, 5103: Brush, 5104: Operation button, 5150: Portable information terminal, 5151: Housing, 5152: Display area, 5153: Bending part, 5120: Dust, 5200: Display area, 5201: Display area, 5202: Display area, 5203: Display area, 7101: Housing, 7103: Display part, 7105: Stand, 7107: Display part, 7109: Operation key, 7110: Remote control operation unit, 7201: Main body, 7202: Housing, 7203: Display part, 7204: Keyboard, 7205: External connection port, 7206: Pointing device, 7210: Second display part, 7401: Housing, 7402: Display part, 7403: Operation button, 7404: External connection port, 7405: Speaker, 7406: Microphone, 9310: Portable information terminal, 9311: Display panel, 9313: Hinge, 9315: Housing,

Claims

1. A light-emitting device having a light-emitting layer between a pair of electrodes, wherein the light-emitting layer includes an organic compound represented by the following general formula (G1) and a fluorescent light-emitting material. 【Chemical 1】 (However, in the above general formula (G1), R １ to R ８ are each independently any one of hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, and a substituted or unsubstituted diarylamino group. Note that R １ to R ８ are such that at least one of them is a substituted or unsubstituted diarylamino group. Further, α represents a substituted or unsubstituted phenylene group, n is an integer of 0 to 4. Also, A represents a substituted or unsubstituted benzofuropyrimidine skeleton or a benzothienopyrimidine skeleton.)

2. The light-emitting device according to claim 1, wherein A is a group represented by the following general formula (g1). [Chemical 2] (However, in the above general formula (g1), R １１ to R １６ One of them is a bond, and the rest are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, and an aryl group having 6 to 13 carbon atoms that forms a substituted or unsubstituted ring. Also, Q represents an oxygen atom or a sulfur atom.)

3. A light-emitting device having a light-emitting layer between a pair of electrodes, wherein the light-emitting layer includes an organic compound represented by the following general formula (G2) and a fluorescent light-emitting material. 【Chemical Formula 3】 (However, in the above general formula (G2), R １ to R ８ are each independently one of hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, and a substituted or unsubstituted diarylamino group. Note that R １ to R ８ are such that at least one of them is a substituted or unsubstituted diarylamino group. Further, α represents a substituted or unsubstituted phenylene group, and n is an integer from 0 to 4. Also, R １１ to R １５ are each independently one of hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, and an aryl group having 6 to 13 carbon atoms that forms a substituted or unsubstituted ring. Further, Q represents an oxygen atom or a sulfur atom.)

4. The light-emitting device according to any one of claims 1 to 3, wherein the substituted or unsubstituted diarylamino group is a group represented by the following general formula (g2). 【Chemical Formula 4】 (However, in the above general formula (g2), Ar １ and Ar ２ each independently represents an aryl group having 6 to 13 carbon atoms that forms a substituted or unsubstituted ring.)

5. The light-emitting device according to claim 4, R ３ and R ６ A light-emitting device in which one or both of them are groups represented by the general formula (g2).

6. A light-emitting device having a light-emitting layer between a pair of electrodes, wherein the light-emitting layer includes an organic compound represented by the following general formula (G3) and a fluorescent light-emitting material. 【Chemical Formula 5】 (However, in the above general formula (G3), Ar ３ to Ar ６ are each independently any of aryl groups having 6 to 13 carbon atoms that form a substituted or unsubstituted ring. Also, R １ , R ２ , R ４ , R ５ , R ７ and R ８ are each independently any one of hydrogen, an alkyl group having 1 to 6 carbon atoms, and a cycloalkyl group having 3 to 7 carbon atoms. Also, α represents a substituted or unsubstituted phenylene group, and n is an integer from 0 to 4. Also, R １１ to R １５ are each independently any of hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, and an aryl group having 6 to 13 carbon atoms that form a substituted or unsubstituted ring. Also, Q represents an oxygen atom or a sulfur atom.)

7. A light-emitting device having a light-emitting layer between a pair of electrodes, wherein the light-emitting layer includes an organic compound represented by the following general formula (G4) and a fluorescent light-emitting material. 【Chemical Formula 6】 (However, in the above general formula (G4), Ar ３ to Ar ６ are each independently any of aryl groups having 6 to 13 carbon atoms that form a substituted or unsubstituted ring. Further, α represents a substituted or unsubstituted phenylene group, and n is an integer from 0 to 4. Further, R １３ is any of hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, and an aryl group having 6 to 13 carbon atoms that form a substituted or unsubstituted ring. Further, Q represents an oxygen atom or a sulfur atom.)

8. A light-emitting device having a light-emitting layer between a pair of electrodes, wherein the light-emitting layer includes an organic compound represented by the following general formula (G5) and a fluorescent light-emitting material. 【Chemical Formula 7】 (However, in the above general formula (G5), Ar ３ to Ar ６ are each independently any of aryl groups having 6 to 13 carbon atoms that form a substituted or unsubstituted ring. Further, R １３ is any of hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, and an aryl group having 6 to 13 carbon atoms that form a substituted or unsubstituted ring. Further, Q represents an oxygen atom or a sulfur atom.)

9. The light-emitting device according to any one of claims 2 to 8, wherein Q is an oxygen atom.

10. The light-emitting device according to any one of claims 1 to 9, wherein the difference between the lowest singlet excitation level and the lowest triplet excitation level is 0.2 eV or less.

11. An electronic device including the light-emitting device according to any one of claims 1 to 10 and at least one of a sensor, an operation button, a speaker, and a microphone.

12. A light-emitting device including the light-emitting device according to any one of claims 1 to 10 and at least one of a transistor and a substrate.

13. A lighting device including the light-emitting device according to any one of claims 1 to 10 and a housing. ​

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