Light-emitting device

Abstract

To provide a light-emitting device with high luminous efficiency.SOLUTION: A light-emitting device includes an anode, a cathode, and an EL layer existing therebetween. The EL layer includes a light-emitting layer, a first layer, and a second layer. The first layer exists between the anode and the light-emitting layer. The first layer and the second layer are in contact with each other. The second layer includes a monoamine compound with an arylamine structure. In the monoamine compound, a first group, a second group, and a third group are bonded to a nitrogen atom included in the amine. The first group is a group including a carbazole structure. The second group is a group including a dibenzofuran structure or a dibenzothiophene structure. The third group includes an aromatic hydrocarbon structure with 6 to 18 carbons or a heteroaromatic hydrocarbon structure with 4 to 26 carbons. The refractive index of the first layer is lower than that of the light-emitting layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One embodiment 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 embodiment of the present invention is not limited to the above technical field. The technical field of one embodiment of the invention disclosed in this specification etc. relates to an object, a method, or a manufacturing method. Alternatively, one embodiment of the present invention relates to a process, a machine, manufacture, or a composition of matter. Therefore, more specific examples of the technical field of one embodiment of the present invention disclosed in this specification include semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, lighting devices, power storage devices, memory devices, imaging devices, driving methods thereof, and manufacturing methods thereof. [Background technology]

[0002] Light-emitting devices (organic EL devices) that utilize electroluminescence (EL) using organic compounds are becoming more and more common. The basic structure of these light-emitting devices is a pair of electrodes sandwiching an organic compound layer (EL layer) containing a light-emitting material between them. By applying a voltage to this device, carriers are injected, and the recombination energy of these carriers is utilized to emit light from the light-emitting material.

[0003] Since such light-emitting devices are self-luminous, when used as display pixels, they offer advantages such as higher visibility and no need for backlighting compared to liquid crystal displays, making them particularly suitable for flat panel displays. Another major advantage of displays using such light-emitting devices is that they can be fabricated to be thin and lightweight. Another feature is their extremely fast response time.

[0004] Furthermore, these light-emitting devices can emit light continuously in two dimensions, making it possible to obtain surface light emission. This is a feature that is difficult to obtain with point light sources such as incandescent bulbs and LEDs, or linear light sources such as fluorescent lamps, making them highly useful as surface light sources for lighting applications.

[0005] Displays and lighting devices using such light-emitting devices are suitable for a variety of electronic devices, but research and development is ongoing to find light-emitting devices with even better characteristics.

[0006] One of the problems often cited when discussing organic EL devices is their low light extraction efficiency. To improve this, a structure has been proposed in which a layer made of a low refractive index material is formed inside the EL layer (see, for example, Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] Jaeho Lee and 12 others, "Synergetic electrode architecture for efficient graphene-based flexible organic light-emitting diodes," Nature Communications, June 2, 2016, DOI: 10.1038 / ncomms11791 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of one embodiment of the present invention is to provide a light-emitting device with high emission efficiency. Alternatively, an object of another embodiment of the present invention is to provide a light-emitting device with low driving voltage. Alternatively, an object of another embodiment of the present invention is to provide a light-emitting device with a long lifetime. Another embodiment of the present invention is to provide any one of a light-emitting device, a light-emitting device, an electronic device, a display device, and an electronic device with low power consumption. Another embodiment of the present invention is to provide any one of a light-emitting device, a light-emitting device, an electronic device, a display device, and an electronic device with high reliability.

[0009] The present invention is intended to solve any one of the above problems. [Means for solving the problem]

[0010] One embodiment of the present invention is a light-emitting device comprising: an anode, a cathode, and an EL layer located between the anode and the cathode; the EL layer comprises an emitting layer, a first layer, and a second layer; the first layer is located between the anode and the emitting layer, and the first layer and the second layer are in contact with each other; the second layer comprises a first organic compound having an arylamine structure; the first organic compound has a nitrogen atom constituting the amine, to which a first group, a second group, and a third group are bonded; the first group is a group having a carbazole structure; the second group is a group having a dibenzofuran structure or a dibenzothiophene structure; and the third group has an aromatic hydrocarbon structure having 6 to 18 carbon atoms or a heteroaromatic hydrocarbon structure having 4 to 26 carbon atoms; and the refractive index of the first layer is lower than that of the emitting layer.

[0011] Another embodiment of the present invention is a light-emitting device comprising: an anode, a cathode, and an EL layer located between the anode and the cathode; the EL layer comprises an emitting layer, a first layer, and a second layer; the first layer is located between the anode and the emitting layer, and the first layer and the second layer are in contact with each other; the second layer comprises a first organic compound having an arylamine structure; the first organic compound has a nitrogen atom constituting the amine, to which a first group, a second group, and a third group are bonded; the first group is a group having a carbazole structure; the second group is a group having a dibenzofuran structure or a dibenzothiophene structure; and the third group has an aromatic hydrocarbon structure having 6 to 18 carbon atoms or a heteroaromatic hydrocarbon structure having 4 to 26 carbon atoms; and the first layer has an ordinary refractive index of 1.5 to 1.75 for light having a wavelength of 455 nm to 465 nm.

[0012] Another embodiment of the present invention is a light-emitting device comprising: an anode, a cathode, and an EL layer located between the anode and the cathode; the EL layer comprises an emitting layer, a first layer, and a second layer; the first layer is located between the anode and the emitting layer, and the first layer and the second layer are in contact with each other; the second layer comprises a first organic compound having an arylamine structure; the first organic compound has a nitrogen atom constituting the amine, to which a first group, a second group, and a third group are bonded; the first group is a group having a carbazole structure; the second group is a group having a dibenzofuran structure or a dibenzothiophene structure; and the third group has an aromatic hydrocarbon structure having 6 to 18 carbon atoms or a heteroaromatic hydrocarbon structure having 4 to 26 carbon atoms; and the refractive index of the first layer with respect to light having a wavelength of 633 nm is 1.45 to 1.70.

[0013] Alternatively, another embodiment of the present invention provides a light-emitting device comprising an anode, a cathode, and an EL layer located between the anode and the cathode, the EL layer comprising a light-emitting layer, a first layer, and a second layer, the first layer being located between the anode and the light-emitting layer, the first layer being in contact with the second layer, the second layer including a first organic compound having a triarylamine structure, the first organic compound having a nitrogen atom constituting the amine with a first group, a second group, and a third group bonded to the nitrogen atom, the first group is a group containing a carbazole structure, the second group is a group containing a dibenzofuran structure or a dibenzothiophene structure, the third group contains an aromatic hydrocarbon structure having 6 to 18 carbon atoms or a heteroaromatic hydrocarbon structure having 4 to 26 carbon atoms, the first layer contains an organic compound having hole-transporting properties, and the organic compound having hole-transporting properties has an ordinary refractive index of 1.5 or more and 1.75 or less for light with a wavelength of 455 nm or more and 465 nm or less.

[0014] Alternatively, another embodiment of the present invention provides a light-emitting device comprising an anode, a cathode, and an EL layer located between the anode and the cathode, the EL layer including a light-emitting layer, a first layer, and a second layer, the first layer being located between the anode and the light-emitting layer, the first layer being in contact with the second layer, the second layer including a first organic compound having a triarylamine structure, and the first organic compound having a first group, a second group, and a third group bonded to a nitrogen atom constituting the amine, the first group is a group containing a carbazole structure, the second group is a group containing a dibenzofuran structure or a dibenzothiophene structure, the third group contains an aromatic hydrocarbon structure having 6 to 18 carbon atoms or a heteroaromatic hydrocarbon structure having 4 to 26 carbon atoms, the first layer contains an organic compound having hole-transporting properties, and the refractive index of the organic compound having hole-transporting properties for light with a wavelength of 633 nm is 1.45 or more and 1.70 or less in a light-emitting device.

[0015] Another embodiment of the present invention is a light-emitting device having the above structure, in which the organic compound having a hole-transport property has a plurality of alkyl groups.

[0016] Alternatively, another embodiment of the present invention is a light-emitting device having the above-described structure, wherein the carbazole structure in the first group has a bond at any one of the 2-position, the 3-position, and the carbazole structure is bonded to the nitrogen atom via the bond or via the bond and a divalent aromatic hydrocarbon group.

[0017] Alternatively, another embodiment of the present invention is a light-emitting device having the above structure, wherein the carbazole structure in the first group has a bond at the second or third position, and the carbazole structure is bonded to the nitrogen atom via the bond or via the bond and a divalent aromatic hydrocarbon group.

[0018] Alternatively, another embodiment of the present invention is a light-emitting device having the above structure, wherein the carbazole structure in the first group has a bond at the second position, and the carbazole structure is bonded to the nitrogen atom via the bond or via the bond and a divalent aromatic hydrocarbon group.

[0019] Another aspect of the present invention is a light-emitting device having the above structure, wherein the divalent aromatic hydrocarbon group is a phenylene group.

[0020] Alternatively, another embodiment of the present invention is a light-emitting device having the above structure, wherein the dibenzofuran structure and the dibenzothiophene structure in the second group are bonded to the nitrogen atom via a divalent aromatic hydrocarbon group.

[0021] Alternatively, another embodiment of the present invention is a light-emitting device having the above structure, wherein the divalent aromatic hydrocarbon group included in the second group is a phenylene group or a biphenyldiyl group.

[0022] Another embodiment of the present invention is a light-emitting device having the above structure, wherein a bond of the phenylene group or a bond of at least one benzene structure in the biphenyldiyl group is in a meta position.

[0023] Alternatively, another embodiment of the present invention is a light-emitting device having the above structure, wherein the third group is a biphenyl group or a terphenyl group.

[0024] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the third group is a group containing a dibenzofuran structure or a dibenzothiophene structure.

[0025] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the second layer is located between the first layer and the light-emitting layer.

[0026] Another embodiment of the present invention is a light-emitting device including an anode, a cathode, and an EL layer located between the anode and the cathode, the EL layer including a light-emitting layer, a first layer, and a second layer, the first layer being located between the anode and the light-emitting layer, the first layer being in contact with the second layer, the refractive index of the first layer being lower than the refractive index of the light-emitting layer, and the second layer including an organic compound represented by the following general formula (G1):

[0027] [ka]

[0028] However, in the above general formula (G1), Ar 1 is a group represented by the following general formula (g1), and Ar 2 is a group represented by the following general formula (g2) or (g3), and Ar 3 is either a group represented by the following general formula (g1) or an aromatic hydrocarbon group having 6 to 18 carbon atoms.

[0029] [ka]

[0030] However, in the above general formulas (g1) to (g3), R 1 ~R 6are each independently either a hydrocarbon group having 1 to 6 carbon atoms or an aromatic hydrocarbon group having 6 to 13 carbon atoms, and Ar 4 is a substituted or unsubstituted phenyl group. Furthermore, a, c, d, and e each independently represent an integer of 0 to 4, and b and f each independently represent an integer of 0 to 3. Furthermore, L 1 ~L 3 each independently represents a divalent aromatic hydrocarbon group having 6 to 12 carbon atoms, and X is an oxygen atom or a sulfur atom.

[0031] Another embodiment of the present invention is a light-emitting device comprising an anode, a cathode, and an EL layer located between the anode and the cathode, the EL layer including a light-emitting layer, a first layer, and a second layer, the first layer being located between the anode and the light-emitting layer, the first layer being in contact with the second layer, the first layer having an ordinary refractive index of 1.5 to 1.75 for light having a wavelength of 455 nm to 465 nm, and the second layer including an organic compound represented by the following general formula (G1):

[0032] [ka]

[0033] However, in the above general formula (G1), Ar 1 is a group represented by the following general formula (g1), and Ar 2 is a group represented by the following general formula (g2) or (g3), and Ar 3 is either a group represented by the following general formula (g1) or an aromatic hydrocarbon group having 6 to 18 carbon atoms.

[0034] [ka]

[0035] However, in the above general formulas (g1) to (g3), R 1 ~R 6 are each independently either a hydrocarbon group having 1 to 6 carbon atoms or an aromatic hydrocarbon group having 6 to 13 carbon atoms, and Ar 4is a substituted or unsubstituted phenyl group. Furthermore, a, c, d, and e each independently represent an integer of 0 to 4, and b and f each independently represent an integer of 0 to 3. Furthermore, L 1 ~L 3 each independently represents a divalent aromatic hydrocarbon group having 6 to 12 carbon atoms, and X is an oxygen atom or a sulfur atom.

[0036] Another embodiment of the present invention is a light-emitting device comprising an anode, a cathode, and an EL layer located between the anode and the cathode, the EL layer including a light-emitting layer, a first layer, and a second layer, the first layer being located between the anode and the light-emitting layer, the first layer being in contact with the second layer, the refractive index of the first layer with respect to light having a wavelength of 633 nm being 1.45 or more and 1.70 or less, and the second layer including an organic compound represented by the following general formula (G1):

[0037] [ka]

[0038] However, in the above general formula (G1), Ar 1 is a group represented by the following general formula (g1), and Ar 2 is a group represented by the following general formula (g2) or (g3), and Ar 3 is either a group represented by the following general formula (g1) or an aromatic hydrocarbon group having 6 to 18 carbon atoms.

[0039] [ka]

[0040] However, in the above general formulas (g1) to (g3), R 1 ~R 6 are each independently either a hydrocarbon group having 1 to 6 carbon atoms or an aromatic hydrocarbon group having 6 to 13 carbon atoms, and Ar 4 is a substituted or unsubstituted phenyl group. Furthermore, a, c, d, and e each independently represent an integer of 0 to 4, and b and f each independently represent an integer of 0 to 3. Furthermore, L1 ~L 3 each independently represents a divalent aromatic hydrocarbon group having 6 to 12 carbon atoms, and X is an oxygen atom or a sulfur atom.

[0041] Another embodiment of the present invention is a light-emitting device including an anode, a cathode, and an EL layer located between the anode and the cathode. The EL layer includes a light-emitting layer, a first layer, and a second layer. The first layer is located between the anode and the light-emitting layer and is in contact with the second layer. The first layer contains an organic compound having a hole-transporting property. The organic compound having a hole-transporting property has an ordinary refractive index of 1.5 to 1.75 for light with a wavelength of 455 nm to 465 nm. The second layer contains an organic compound represented by the following general formula (G1):

[0042] [ka]

[0043] However, in the above general formula (G1), Ar 1 is a group represented by the following general formula (g1), and Ar 2 is a group represented by the following general formula (g2) or (g3), and Ar 3 is either a group represented by the following general formula (g1) or an aromatic hydrocarbon group having 6 to 18 carbon atoms.

[0044] [ka]

[0045] However, in the above general formulas (g1) to (g3), R 1 ~R 6 are each independently either a hydrocarbon group having 1 to 6 carbon atoms or an aromatic hydrocarbon group having 6 to 13 carbon atoms, and Ar 4 is a substituted or unsubstituted phenyl group. Furthermore, a, c, d, and e each independently represent an integer of 0 to 4, and b and f each independently represent an integer of 0 to 3. Furthermore, L 1 ~L 3each independently represents a divalent aromatic hydrocarbon group having 6 to 12 carbon atoms, and X is an oxygen atom or a sulfur atom.

[0046] Another embodiment of the present invention is a light-emitting device including an anode, a cathode, and an EL layer located between the anode and the cathode. The EL layer includes a light-emitting layer, a first layer, and a second layer. The first layer is located between the anode and the light-emitting layer and is in contact with the second layer. The first layer contains an organic compound having a hole-transporting property, and the refractive index of the organic compound having a hole-transporting property with respect to light having a wavelength of 633 nm is 1.45 to 1.70. The second layer contains an organic compound represented by the following general formula (G1):

[0047] [ka]

[0048] However, in the above general formula (G1), Ar 1 is a group represented by the following general formula (g1), and Ar 2 is a group represented by the following general formula (g2) or (g3), and Ar 3 is either a group represented by the following general formula (g1) or an aromatic hydrocarbon group having 6 to 18 carbon atoms.

[0049] [ka]

[0050] However, in the above general formulas (g1) to (g3), R 1 ~R 6 are each independently either a hydrocarbon group having 1 to 6 carbon atoms or an aromatic hydrocarbon group having 6 to 13 carbon atoms, and Ar 4 is a substituted or unsubstituted phenyl group. Furthermore, a, c, d, and e each independently represent an integer of 0 to 4, and b and f each independently represent an integer of 0 to 3. Furthermore, L 1 ~L 3each independently represents a divalent aromatic hydrocarbon group having 6 to 12 carbon atoms, and X is an oxygen atom or a sulfur atom.

[0051] Another embodiment of the present invention is a light-emitting device having the above structure, in which the organic compound having a hole-transport property has a plurality of alkyl groups.

[0052] Another embodiment of the present invention is a light-emitting device having the above structure, in which X is a sulfur atom.

[0053] Alternatively, another embodiment of the present invention is a method for manufacturing a semiconductor device according to the above-mentioned embodiment, wherein L 1 is any one of the groups represented by the following structural formulas (L-1) to (L-7).

[0054] [ka]

[0055] Alternatively, another embodiment of the present invention is a method for manufacturing a semiconductor device according to the above-mentioned embodiment, wherein L 1 is a group represented by the following structural formula (L-2) or (L-6).

[0056] [ka]

[0057] However, (L-6) is bound to the nitrogen atom at the asterisk position.

[0058] Alternatively, another aspect of the present invention is the above-mentioned structure, wherein the Ar 2 is a group represented by the following general formula (g3-1) or (g3-2).

[0059] [ka]

[0060] However, in the above general formula (g3-1) or (g3-2), R 5 and R 6 are each independently either a hydrocarbon group having 1 to 6 carbon atoms or an aromatic hydrocarbon group having 6 to 13 carbon atoms, and Ar 4 is a substituted or unsubstituted phenyl group, e is an integer of 0 to 4, and f is an integer of 0 to 3. 3 represents a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms.

[0061] Alternatively, another aspect of the present invention is the above-mentioned structure, wherein the Ar 2 is a group represented by (g3-1).

[0062] Alternatively, another aspect of the present invention is the above-mentioned structure, wherein the Ar 3 is represented by the following general formula (Ar 3 -1) or (Ar 3 The light-emitting device is a group represented by formula (2).

[0063] [ka]

[0064] However, (Ar 3 In (Ar −1), s and t are each independently 0 or 1. 3 -2), R 1 and R 2 are each independently either a hydrocarbon group having 1 to 6 carbon atoms or an aromatic hydrocarbon group having 6 to 13 carbon atoms, a represents an integer of 0 to 4, and b represents an integer of 0 to 3. 1 represents a divalent aromatic hydrocarbon group having 6 to 12 carbon atoms.

[0065] Alternatively, another embodiment of the present invention is a method for manufacturing a semiconductor device according to the present invention, wherein Ar 3 is represented by the general formula (Ar 3 The light-emitting device is a group represented by formula (2).

[0066] Alternatively, another aspect of the present invention is the above-mentioned structure, wherein the Ar 3 is represented by the following structural formula (Ar 3 -1-1) or (Ar 3 -1-2).

[0067] [ka]

[0068] Alternatively, another aspect of the present invention is the above-mentioned structure, wherein the Ar 3 is represented by the following structural formula (Ar 3 -1-1).

[0069] Another embodiment of the present invention is a light-emitting device having the above structure, in which the organic compound represented by General Formula (G1) is an organic compound represented by General Formula (G2):

[0070] [ka]

[0071] In the above general formula (G2), X is an oxygen atom or a sulfur atom, and Ar 5 is a substituted or unsubstituted phenyl group, m is 0 or 1, and n is an integer of 0 to 2.

[0072] Another embodiment of the present invention is a light-emitting device having the above structure, wherein the second layer is located between the first layer and the light-emitting layer.

[0073] Another embodiment of the present invention is a material for a light-emitting device represented by General Formula (G1) or General Formula (G2) that is used for the second layer in the above structure.

[0074] Another embodiment of the present invention is an organic compound represented by the following general formula (G2).

[0075] [ka]

[0076] In the above general formula (G2), X is an oxygen atom or a sulfur atom, and Ar 5 is a substituted or unsubstituted phenyl group, m is 0 or 1, and n is an integer of 0 to 2.

[0077] Another embodiment of the present invention is an organic compound having the above structure, in which X is a sulfur atom.

[0078] Another embodiment of the present invention is an organic compound having the above structure, in which n is 1.

[0079] Another embodiment of the present invention is an organic compound represented by the following structural formula (100):

[0080] [ka]

[0081] Another embodiment of the present invention is an organic compound represented by the following structural formula (101):

[0082] [ka]

[0083] Another embodiment of the present invention is an organic compound represented by the following structural formula (104):

[0084] [ka]

[0085] Another embodiment of the present invention is an organic compound represented by the following structural formula (103):

[0086] [ka]

[0087] Another embodiment of the present invention is an electronic device including any of the above electronic devices or light-emitting devices, and a sensor, an operation button, a speaker, or a microphone.

[0088] Another embodiment of the present invention is a light-emitting device including the above light-emitting device and a transistor or a substrate.

[0089] Another embodiment of the present invention is a lighting device including the above-described light-emitting device and a housing.

[0090] In this specification, the term "light-emitting device" includes an image display device using a light-emitting device. The term "light-emitting device" may also include a module in which a connector, such as an anisotropic conductive film or TCP (Tape Carrier Package), is attached to a light-emitting device, a module in which a printed wiring board is provided at the end of the TCP, or a module in which an IC (integrated circuit) is directly mounted on a light-emitting device using a COG (Chip On Glass) method. Furthermore, lighting fixtures and the like may include a light-emitting device. [Effects of the Invention]

[0091] According to one embodiment of the present invention, a light-emitting device with high emission efficiency can be provided. Alternatively, according to one embodiment of the present invention, a light-emitting device with low driving voltage can be provided. Alternatively, according to another embodiment of the present invention, a light-emitting device with long lifetime can be provided. Alternatively, according to one embodiment of the present invention, any of a light-emitting device, a light-emitting device, an electronic device, a display device, and an electronic device with low power consumption can be provided. Alternatively, according to one embodiment of the present invention, any of a light-emitting device, a light-emitting device, an electronic device, a display device, and an electronic device with high reliability can be provided.

[0092] Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. Note that effects other than these will become apparent from the description in the specification, drawings, claims, etc., and it is possible to extract other effects from the description in the specification, drawings, claims, etc. [Brief explanation of the drawings]

[0093] [Figure 1] 1A, 1B, 1C and 1D are schematic diagrams of light emitting devices. [Figure 2] 2A and 2B are diagrams showing an active matrix light emitting device. [Figure 3] 3A and 3B are diagrams showing an active matrix light emitting device. [Figure 4] FIG. 4 is a diagram showing an active matrix light emitting device. [Figure 5] 5A and 5B are diagrams showing a passive matrix light emitting device. [Figure 6] 6A and 6B are diagrams illustrating a lighting device. [Figure 7] 7A, 7B1, 7B2 and 7C are diagrams showing electronic devices. [Figure 8] 8A, 8B and 8C are diagrams showing electronic devices. [Figure 9] FIG. 9 is a diagram showing a lighting device. [Figure 10] FIG. 10 is a diagram showing a lighting device. [Figure 11] FIG. 11 is a diagram showing an in-vehicle display device and a lighting device. [Figure 12] 12A and 12B are diagrams illustrating electronic devices. [Figure 13] 13A, 13B and 13C are diagrams showing electronic devices. [Figure 14] FIG. 14 shows the luminance-current density characteristics of Light-Emitting Device 1, Light-Emitting Device 2, and Comparative Light-Emitting Devices 1 to 3. [Figure 15] FIG. 15 shows the luminance-voltage characteristics of the light-emitting device 1, the light-emitting device 2, and the comparative light-emitting devices 1 to 3. In FIG. [Figure 16] FIG. 16 shows the current efficiency-luminance characteristics of the light-emitting device 1, the light-emitting device 2, and the comparative light-emitting devices 1 to 3. [Figure 17] FIG. 17 shows the current-voltage characteristics of the light-emitting device 1, the light-emitting device 2, and the comparative light-emitting devices 1 to 3. In FIG. [Figure 18] FIG. 18 shows the external quantum efficiency-luminance characteristics of the light-emitting device 1, the light-emitting device 2, and the comparative light-emitting devices 1 to 3. [Figure 19] FIG. 19 shows the power efficiency-luminance characteristics of the light-emitting device 1, the light-emitting device 2, and the comparative light-emitting devices 1 to 3. As shown in FIG. [Figure 20] FIG. 20 shows the emission spectra of the light-emitting device 1, the light-emitting device 2, and the comparative light-emitting devices 1 to 3. In FIG. [Figure 21] FIG. 21 shows the normalized luminance vs. time change characteristics of the light-emitting device 1, the light-emitting device 2, and the comparative light-emitting devices 1 to 3. [Figure 22] FIG. 22 shows the current density-voltage characteristics of Device 3, Device 4, and Comparative Devices 4 to 7. [Figure 23] FIG. 23 shows the luminance-current density characteristics of the light-emitting device 5, the light-emitting device 6, and the comparative light-emitting devices 8 to 11. [Figure 24] FIG. 24 shows the luminance-voltage characteristics of the light-emitting device 5, the light-emitting device 6, and the comparative light-emitting devices 8 to 11. [Figure 25] FIG. 25 shows the current efficiency-luminance characteristics of the light-emitting device 5, the light-emitting device 6, and the comparative light-emitting devices 8 to 11. [Figure 26] FIG. 26 shows the current-voltage characteristics of the light-emitting device 5, the light-emitting device 6, and the comparative light-emitting devices 8 to 11. [Figure 27]FIG. 27 shows the external quantum efficiency-luminance characteristics of the light-emitting device 5, the light-emitting device 6, and the comparative light-emitting devices 8 to 11. [Figure 28] FIG. 28 shows the power efficiency-luminance characteristics of the light-emitting device 5, the light-emitting device 6, and the comparative light-emitting devices 8 to 11. [Figure 29] FIG. 29 shows the emission spectra of the light-emitting device 5, the light-emitting device 6, and the comparative light-emitting devices 8 to 11. [Figure 30] FIG. 30 shows the luminance-current density characteristics of the light-emitting device 7. [Figure 31] FIG. 31 shows the luminance-voltage characteristics of the light-emitting device 7. [Figure 32] FIG. 32 shows the current efficiency-luminance characteristics of the light-emitting device 7. [Figure 33] FIG. 33 shows the current-voltage characteristics of the light-emitting device 7. [Figure 34] FIG. 34 shows the external quantum efficiency-luminance characteristics of the light-emitting device 7. [Figure 35] FIG. 35 shows the power efficiency-luminance characteristics of the light-emitting device 7. [Figure 36] FIG. 36 shows the emission spectrum of the light-emitting device 7. [Figure 37] FIG. 37 shows the luminance-current density characteristics of the light-emitting device 8 and the comparative light-emitting device 12. [Figure 38] FIG. 38 shows the luminance-voltage characteristics of the light-emitting device 8 and the comparative light-emitting device 12. [Figure 39] FIG. 39 shows the current efficiency-luminance characteristics of the light-emitting device 8 and the comparative light-emitting device 12. [Figure 40] FIG. 40 shows the current-voltage characteristics of the light-emitting device 8 and the comparative light-emitting device 12. [Figure 41] FIG. 41 shows the BI-luminance characteristics of the light-emitting device 8 and the comparative light-emitting device 12. [Figure 42] FIG. 42 shows the emission spectra of light-emitting device 8 and comparative light-emitting device 12. [Figure 43]FIG. 43 shows the normalized luminance vs. time change characteristics of the light-emitting device 8 and the comparative light-emitting device 12. [Figure 44] Figures 44A and 44B are 1H-NMR charts of PCBBiPDBt-02. [Figure 45] FIG. 45 shows the absorption and emission spectra of PCBBiPDBt-02 in a solution state. [Figure 46] FIG. 46 shows the absorption and emission spectra of PCBBiPDBt-02 in a thin film state. [Figure 47] Figure 47 is the MS spectrum of PCBBiPDBt-02. [Figure 48] Figures 48A and 48B are 1H-NMR charts of mPCBBiPDBt-02. [Figure 49] FIG. 49 shows the absorption and emission spectra of mPCBBiPDBt-02 in a solution state. [Figure 50] FIG. 50 shows the absorption and emission spectra of mPCBBiPDBt-02 in a thin film state. [Figure 51] Figure 51 is the MS spectrum of mPCBBiPDBt-02. [Figure 52] Figures 52A and 52B are 1H-NMR charts of pmPCBBiBPDBt-02. [Figure 53] FIG. 53 shows the absorption and emission spectra of pmPCBBiBPDBt-02 in a solution state. [Figure 54] Figure 54 shows the absorption and emission spectra of pmPCBBiBPDBt-02 in a thin film state. [Figure 55] Figure 55 is the MS spectrum of pmPCBBiBPDBt-02. [Figure 56] Figures 56A and 56B are 1H-NMR charts of pmPCBBiPDBt. [Figure 57] FIG. 57 shows the absorption and emission spectra of pmPCBBiPDBt in solution. [Figure 58] Figure 58 shows the absorption and emission spectra of pmPCBBiPDBt in a thin film state. [Figure 59] Figures 59A and 59B are 1H-NMR charts of pmPCBBiBPDBf-02. [Figure 60] FIG. 60 shows the absorption and emission spectra of pmPCBBiBPDBf-02 in solution. [Figure 61] FIG. 61 shows the absorption and emission spectra of pmPCBBiBPDBf-02 in a thin film state. [Figure 62] Figures 62A and 62B are 1H-NMR charts of pmPCBiBPDBt-02. [Figure 63] FIG. 63 shows the absorption and emission spectra of pmPCBiBPDBt-02 in solution. [Figure 64] Figure 64 shows the absorption and emission spectra of pmPCBiBPDBt-02 in a thin film state. [Figure 65] Figures 65A and 65B are 1H-NMR charts of mmtBuBidFBi. [Figure 66] FIG. 66 shows the absorption and emission spectra of mmtBuBidFBi in solution. DETAILED DESCRIPTION OF THE INVENTION

[0094] 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 readily understood by those skilled in the art that various changes in form and details can be made without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the description of the embodiments shown below.

[0095] (Embodiment 1) FIG. 1A shows a light-emitting device according to one embodiment of the present invention. FIG. 1 shows a structure including an anode 101, a cathode 102, and an EL layer 103. The EL layer includes a hole-transport region 120, a light-emitting layer 113, an electron-transport layer 114, and an electron-injection layer 115. The light-emitting layer 113 is a layer containing at least a light-emitting material, and the hole-transport region 120 includes a hole-transport layer 112, a hole-injection layer 111, an electron-blocking layer 125, and the like. The configuration of the EL layer 103 is not limited to this, and it may include some of the above layers, or may include other functional layers such as a hole-blocking layer, an exciton-blocking layer, or an intermediate layer.

[0096] In one embodiment of the present invention, a low refractive index layer is provided in the region (hole transport region 120) between the light emitting layer 113 and the anode 101 in the EL layer 103.

[0097] The low refractive index layer is a layer-like region roughly parallel to the anode 101 or the cathode 102, and is a region that exhibits a refractive index lower than at least the light-emitting layer 113. Since the refractive index of organic compounds that constitute light-emitting devices is typically about 1.8 to 1.9, the refractive index of the low refractive index layer is preferably 1.75 or less, more specifically, the ordinary refractive index in the blue light-emitting region (455 nm to 465 nm) is preferably 1.50 to 1.75, or the ordinary refractive index for 633 nm light, which is typically used for measuring refractive index, is preferably 1.45 to 1.70. Such a low refractive index layer can be formed by using a material and a manufacturing method that will result in a film that exhibits the refractive index values described above.

[0098] When light is incident on a material with optical anisotropy, the light in the vibration plane parallel to the optical axis is called extraordinary light (ray), and the light in the vibration plane perpendicular to the optical axis is called ordinary light (ray). However, the refractive index of the material for ordinary light and extraordinary light may differ. In such cases, anisotropy analysis can be performed to separate the ordinary and extraordinary refractive indices and calculate each refractive index. In this specification, if the measured material has both an ordinary refractive index and an extraordinary refractive index, the ordinary refractive index will be used as the index. When simply referring to refractive index, it is common to refer to the average of the ordinary and extraordinary refractive indices.

[0099] Furthermore, the entire hole transport region 120 does not need to be a low refractive index layer, and it is sufficient that at least a portion of the hole transport region 120 in the thickness direction is provided as a low refractive index layer. For example, it is sufficient that at least one of the functional layers provided in the hole transport region 120, such as the hole injection layer 111, the hole transport layer 112, and the electron blocking layer, is a low refractive index layer. Furthermore, the low refractive index layer may be a portion of these functional layers. In other words, the hole transport layer 112 may be formed of multiple layers, one of which has a low refractive index.

[0100] As mentioned above, a low-refractive index layer can be formed by forming each functional layer using a material with a low refractive index. However, there is usually a trade-off between high carrier transport and a low refractive index. This is because the carrier transport properties of organic compounds are largely due to the presence of unsaturated bonds, and organic compounds with many unsaturated bonds tend to have a high refractive index. Even if a material has a low refractive index, if its carrier transport properties are poor, problems such as increased driving voltage and reduced luminous efficiency and reliability due to carrier imbalance can occur, making it impossible to obtain a light-emitting device with good characteristics. Furthermore, even if a material has sufficient carrier transport properties and a low refractive index, if it has an unstable structure and has problems with the glass transition temperature (Tg) and durability, it will be impossible to obtain a reliable light-emitting device.

[0101] In addition, the carrier injection property at the interface between the low-refractive index layer and other layers, or at the interface between low-refractive index layers, is also important. Organic compounds with low-refractive index hole transport properties have a relatively large hole injection barrier even if they have sufficient hole mobility, and the use of such organic compounds has sometimes resulted in an increase in driving voltage. Even if the introduction of a low-refractive index layer improves extraction efficiency and produces a light-emitting device with high external quantum efficiency, a high driving voltage can be detrimental to energy and power efficiency, and the expected power consumption reduction effect may not be achieved.

[0102] Therefore, one embodiment of the present invention discloses a configuration in which a layer containing an organic compound having a specific structure is provided in contact with the low-refractive-index layer, thereby reducing the carrier injection barrier of the organic compound having a low refractive index and hole-transporting properties and suppressing an increase in driving voltage due to the use of the low-refractive-index layer. Note that the layer containing the organic compound is preferably provided between the low-refractive-index layer and the light-emitting layer.

[0103] The organic compound having the specific structure capable of suppressing an increase in driving voltage is a first organic compound having an arylamine structure in which a first group, a second group, and a third group are bonded to a nitrogen atom, where the first group is a group containing a carbazole structure, the second group is a group containing a dibenzofuran structure or a dibenzothiophene structure, and the third group is a group containing an aromatic hydrocarbon structure having 6 to 18 carbon atoms or a heteroaromatic hydrocarbon structure having 4 to 26 carbon atoms.

[0104] The layer containing the first organic compound having such a structure can be provided adjacent to a layer containing an organic compound with a low refractive index and hole transport properties, thereby specifically improving the driving voltage. By providing such a stacked structure in the hole transport region 120, it is possible to suppress an increase in driving voltage and obtain a light-emitting device with very good external quantum efficiency, power efficiency, and energy efficiency.

[0105] The carbazole structure contained in the first group in the first organic compound preferably has a bond at any one of the 2-, 3-, or 9-positions, and is bonded to the nitrogen of the amine via the bond directly or via a divalent aromatic hydrocarbon group. It is more preferable that the carbazole structure has a bond at the 2- or 3-position and is bonded at the 2- or 3-position, and even more preferable that the carbazole structure has a bond at the 2-position and is bonded at the 2-position. The divalent aromatic hydrocarbon group is preferably a substituted or unsubstituted phenylene group or a substituted or unsubstituted biphenyldiyl group, each of which is more preferably unsubstituted, and even more preferably an unsubstituted p-phenylene group.

[0106] The dibenzofuran structure or dibenzothiophene structure contained in the second group in the first organic compound is preferably bonded to the nitrogen of the amine via a divalent aromatic hydrocarbon group. The divalent aromatic hydrocarbon group is preferably a substituted or unsubstituted phenylene group or a substituted or unsubstituted biphenyldiyl group, and more preferably unsubstituted. It is more preferable that either one of the benzene rings of the phenylene group or biphenyldiyl group contained in the second group is bonded at the meta position.

[0107] Furthermore, when the third group in the first organic compound is an aromatic hydrocarbon structure having 6 to 18 carbon atoms, the aromatic hydrocarbon group is preferably a substituted or unsubstituted phenyl group, a substituted or unsubstituted biphenyl group, or a substituted or unsubstituted terphenyl group, and more preferably an unsubstituted group. Furthermore, when the third group is a biphenyl group or a terphenyl group, it is preferable that any benzene ring contained therein is bonded at the para position.

[0108] When the third group in the first organic compound is a group containing a heteroaromatic hydrocarbon structure having 4 to 26 carbon atoms, the heteroaromatic hydrocarbon structure is preferably a substituted or unsubstituted dibenzofuran structure or a substituted or unsubstituted dibenzothiophene structure, and particularly preferably a dibenzothiophene structure.

[0109] A preferred example of such a first organic compound can be represented by the following general formula (G1).

[0110] [ka]

[0111] However, in the above general formula (G1), Ar 1 is a group represented by the following general formula (g1), and Ar 2 is a group represented by the following general formula (g2) or (g3), and Ar 3 is either a group represented by the following general formula (g1) or an aromatic hydrocarbon group having 6 to 18 carbon atoms.

[0112] [ka]

[0113] However, in the above general formulas (g1) to (g3), R 1 ~R 6 are each independently either a hydrocarbon group having 1 to 6 carbon atoms or an aromatic hydrocarbon group having 6 to 13 carbon atoms, and Ar 4 is a substituted or unsubstituted phenyl group. Furthermore, a, c, d, and e each independently represent an integer of 0 to 4, and b and f each independently represent an integer of 0 to 3. L 1 ~L 3 each independently represents a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 12 carbon atoms, and X represents an oxygen atom or a sulfur atom.

[0114] In the group represented by the general formula (g1), L 1 is particularly preferably a group represented by the following structural formulas (L-1) to (L-7).

[0115] [ka]

[0116] Also, L 1 is more preferably a group represented by the following structural formula (L-1) or (L-6): The group represented by the following structural formula (L-6) is more preferably bonded to the nitrogen atom at the position of the asterisk.

[0117] [ka]

[0118] In addition, in the general formula (G1), Ar 2 is preferably a group represented by the above general formula (g3), more preferably a group represented by the following general formula (g3-1) or general formula (g3-2), and even more preferably a group represented by the following general formula (g3-1).

[0119] [ka]

[0120] However, in the above general formula (g3-1) or (g3-2), R 5 and R 6 are each independently either a hydrocarbon group having 1 to 6 carbon atoms or an aromatic hydrocarbon group having 6 to 13 carbon atoms, and Ar 4 is a substituted or unsubstituted phenyl group, e is an integer of 0 to 4, and f is an integer of 0 to 3. 3 represents a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms.

[0121] In addition, in the organic compound represented by the general formula (G1), Ar 3 is represented by the following general formula (Ar 3 -1), or (Ar 3 -2) is preferred.

[0122] [ka]

[0123] However, (Ar 3 In (Ar −1), s and t are each independently 0 or 1. 3 -2), R 1 and R 2 are each independently either a hydrocarbon group having 1 to 6 carbon atoms or an aromatic hydrocarbon group having 6 to 13 carbon atoms, a represents an integer of 0 to 4, and b represents an integer of 0 to 3. 1 represents a divalent aromatic hydrocarbon group having 6 to 12 carbon atoms.

[0124] Also, (Ar 3 -1) has the following structural formula (Ar 3 -1-1) or structural formula (Ar 3 -1-2), particularly (Ar 3 -1-1) is preferred.

[0125] [ka]

[0126] In the organic compound represented by the general formula (G1), X is preferably a sulfur atom.

[0127] In addition, in the organic compound represented by the general formula (G1), R 1 ~R 6 Specific examples of R include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a tert-butyl group, a pentyl group, a hexyl group, a phenyl group, a biphenyl group, a naphthyl group, and a fluorenyl group. 1 ~R 6 When there are a plurality of alkyl groups, the groups may be the same or different. When two alkyl groups are bonded to adjacent carbon atoms, they may be bonded to each other to form a ring.

[0128] Furthermore, the organic compound represented by the above general formula (G1) is preferably an organic compound represented by the following general formula (G2), since this allows for the provision of a light-emitting device with a better driving voltage.

[0129] [ka]

[0130] In the above general formula (G2), X is an oxygen atom or a sulfur atom, and Ar 5 is a substituted or unsubstituted phenyl group. Furthermore, m is 0 or 1, and n is an integer of 0 to 2. In the organic compound represented by the general formula (G2), X is preferably a sulfur atom, and n is preferably 1.

[0131] Furthermore, in the above description, when it is stated that the substituent is a "substituted or unsubstituted" group, it refers to an alkyl group having 1 to 4 carbon atoms, specifically a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a tert-butyl group, etc.

[0132] Specific examples of organic compounds represented by the general formula (G2) are shown below. Note that these are merely examples.

[0133] [ka]

[0134] [ka]

[0135] [ka]

[0136] [ka]

[0137] [ka]

[0138] [ka]

[0139] [ka]

[0140] The layer containing the first organic compound may be provided as any of the functional layers included in the hole-transport region 120. Since the first organic compound has a LUMO level that makes it effective for use as an electron-blocking layer, it is preferable to provide it as an electron-blocking layer between the hole-transport layer 112 and the light-emitting layer 113. Alternatively, each functional layer may be composed of multiple layers, and a layer containing the first organic compound may be provided as one of the layers. For example, the hole-transport layer may be composed of multiple layers, and one of the layers may be composed of a layer containing the first organic compound.

[0141] Here, as described above, it is very difficult for the organic compound having a low refractive index and hole transport property to constitute the low refractive index layer to simultaneously have high carrier transport property, a low refractive index, and good durability. Therefore, in the light-emitting device according to one embodiment of the present invention, a second organic compound having the following structure is preferred as a material for constituting the low refractive index layer.

[0142] As the second organic compound having hole-transporting properties, it is preferable to use an organic compound having a first aromatic group, a second aromatic group, and a third aromatic group, in which the first aromatic group, the second aromatic group, and the third aromatic group are bonded to the same nitrogen atom.

[0143] In the second organic compound, the ratio of carbon atoms forming bonds with sp3 hybrid orbitals to the total number of carbon atoms in the molecule is preferably 23% or more and 55% or less, and 1The monoamine compound is preferably a compound in which the integral value of a signal below 4 ppm exceeds the integral value of a signal at 4 ppm or more when the compound is measured by H-NMR.

[0144] Furthermore, it is preferable that the second organic compound has at least one fluorene skeleton, and that one or more of the first aromatic group, the second aromatic group, and the third aromatic group have a fluorene skeleton.

[0145] Examples of the second organic compound having hole transport properties include those represented by the following general formula (G h1 1)~(G h1 4) An example of an organic compound having the structure shown below is:

[0146] [ka]

[0147] The general formula (G h1 In 1), Ar 1 , Ar 2 each independently represents a benzene ring or a substituent in which two or three benzene rings are bonded to each other. 1 , Ar 2 one or both of the groups have one or more hydrocarbon groups having 1 to 12 carbon atoms, in which carbon atoms form bonds only through sp3 hybrid orbitals, and Ar 1 and Ar 2 The total number of carbon atoms contained in all the hydrocarbon groups bonded to Ar is 8 or more, and 1 and Ar 2 The total number of carbon atoms contained in all the hydrocarbon groups bonded to either one of Ar 1 or Ar 2 When a plurality of linear alkyl groups having 1 or 2 carbon atoms are bonded to the hydrocarbon group, the linear alkyl groups may be bonded to each other to form a ring.

[0148] [ka]

[0149] The above general formula (G h1 In 2), m and r each independently represent 1 or 2, and m+r is 2 or 3. t represents an integer of 0 to 4, preferably 0. 5 represents either hydrogen or a hydrocarbon group having 1 to 3 carbon atoms. When m is 2, the types of substituents, the number of substituents, and the positions of bonds of the two phenylene groups may be the same or different, and when r is 2, the types of substituents, the number of substituents, and the positions of bonds of the two phenyl groups may be the same or different. When t is an integer of 2 to 4, a plurality of R 5 may be the same or different, and R 5 Adjacent groups may be bonded to each other to form a ring.

[0150] [ka]

[0151] The above general formula (G h1 2) and (G h1 In 3), n and p each independently represent 1 or 2, and n+p is 2 or 3. s represents an integer of 0 to 4, preferably 0. 4 represents either hydrogen or a hydrocarbon group having 1 to 3 carbon atoms, and when n is 2, the types of substituents, the number of substituents, and the positions of bonds of the two phenylene groups may be the same or different, and when p is 2, the types of substituents, the number of substituents, and the positions of bonds of the two phenyl groups may be the same or different. 4 may be the same or different.

[0152] [ka]

[0153] The general formula (G h1 2)~(G h1 4) In R 10 ~R 14 and R 20 ~R 24 Each independently represents hydrogen or a hydrocarbon group having 1 to 12 carbon atoms in which carbon atoms form bonds only through sp3 hybrid orbitals. 10 ~R 14 At least 3 of, and R 20 ~R 24 Preferably, at least 3 of R are hydrogen atoms. As the hydrocarbon group having 1 to 12 carbon atoms in which carbon atoms form bonds only through sp3 hybrid orbitals, a tert-butyl group and a cyclohexyl group are preferred. However, R 10 ~R 14 and R 20 ~R 24 The total number of carbon atoms contained in is 8 or more, and R 10 ~R 14 or R 20 ~R 24 The total number of carbon atoms in either of the two groups must be 6 or more. 4 , R 10 ~R 14 and R 20 ~R 24 Adjacent groups may be bonded to each other to form a ring.

[0154] In addition, the above general formula (G h1 1)~(G h1 In 4), u represents an integer of 0 to 4, and is preferably 0. When u is an integer of 2 to 4, a plurality of R 3 may be the same or different. 1 , R 2 and R 3 each independently represents an alkyl group having 1 to 4 carbon atoms; R 1 and R 2 may be bonded to each other to form a ring.

[0155] Furthermore, as the second organic compound having hole transport properties that can be used in the hole transport region 120, an organic compound having an arylamine structure that has at least one aromatic group, and the aromatic group has first to third benzene rings and at least three alkyl groups, is also preferred. Note that the first to third benzene rings are bonded in this order, and the first benzene ring is directly bonded to the nitrogen of the amine.

[0156] The first benzene ring may further have a substituted or unsubstituted phenyl group, preferably an unsubstituted phenyl group, and the second benzene ring or the third benzene ring may have a phenyl group substituted with an alkyl group.

[0157] It should be noted that hydrogen is not directly bonded to the carbon atoms at the first and third positions of two or more of the first to third benzene rings, preferably all of the benzene rings, but is bonded to any of the first to third benzene rings, the phenyl group substituted with an alkyl group, the at least three alkyl groups, and the nitrogen of the amine.

[0158] The organic compound preferably further has a second aromatic group. The second aromatic group is preferably an unsubstituted monocyclic ring or a group having substituted or unsubstituted fused rings of three or less, more preferably a substituted or unsubstituted fused ring of three or less, the fused ring having 6 to 13 carbon atoms forming the ring, and even more preferably a group having a fluorene ring. The second aromatic group is preferably a dimethylfluorenyl group.

[0159] The organic compound preferably further comprises a third aromatic group, which is a group having one to three substituted or unsubstituted benzene rings.

[0160] The at least three alkyl groups and the alkyl group substituting the phenyl group are preferably chain alkyl groups having 2 to 5 carbon atoms. In particular, the alkyl group is preferably a branched chain alkyl group having 3 to 5 carbon atoms, and more preferably a t-butyl group.

[0161] Examples of the second organic compound having the hole transporting property include the following (G h2 1)~(G h2 3) An example of an organic compound having the structure shown below is an organic compound having the structure shown below.

[0162] [ka]

[0163] In addition, the above general formula (G h2 In 1), Ar 101 represents a substituted or unsubstituted benzene ring, or a substituent in which two or three substituted or unsubstituted benzene rings are bonded to each other.

[0164] [ka]

[0165] In addition, the above general formula (G h2 In 2), x and y each independently represent 1 or 2, and x+y is 2 or 3. 109 represents an alkyl group having 1 to 4 carbon atoms, and w represents an integer of 0 to 4. 141 ~R 145 Each independently represents one of hydrogen, an alkyl group having 1 to 6 carbon atoms, and a cycloalkyl group having 5 to 12 carbon atoms. When w is 2 or more, multiple R 109 may be the same or different. When x is 2, the type of substituents, the number of substituents, and the position of the bond of the two phenylene groups may be the same or different. When y is 2, the two R 141 ~R 145The types and numbers of the substituents on the phenyl groups having the formula (I) may be the same or different.

[0166] [ka]

[0167] In addition, the above general formula (G h2 3) In R 101 ~R 105 each independently represents one of hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 6 to 12 carbon atoms, and a substituted or unsubstituted phenyl group.

[0168] In addition, the above general formula (G h2 1)~(G h2 3) and R 106 , R 107 and R 108 Each independently represents an alkyl group having 1 to 4 carbon atoms, and v represents an integer of 0 to 4. When v is 2 or more, a plurality of R 108 may be the same or different. 111 ~R 115 One of R is a substituent represented by the above general formula (g1), and the rest each independently represent one of hydrogen, an alkyl group having 1 to 6 carbon atoms, and a substituted or unsubstituted phenyl group. 121 ~R 125 One of R is a substituent represented by the above general formula (g2), and the remaining R each independently represent one of hydrogen, an alkyl group having 1 to 6 carbon atoms, and a phenyl group substituted with an alkyl group having 1 to 6 carbon atoms. 131 ~R 135 Each of R independently represents one of hydrogen, an alkyl group having 1 to 6 carbon atoms, and a phenyl group substituted with an alkyl group having 1 to 6 carbon atoms. 111 ~R 115 , R 121 ~R 125 and R 131 ~R 135At least three of the R 111 ~R 115 The number of substituted or unsubstituted phenyl groups in R is 1 or less, 121 ~R 125 and R 131 ~R 135 In R, the number of phenyl groups substituted with alkyl groups having 1 to 6 carbon atoms is 1 or less. 112 and R 114 , R 122 and R 124 , and R 132 and R 134 In at least two of the three combinations, at least one R is other than hydrogen.

[0169] The second organic compound having hole transport properties as described above has an ordinary refractive index of 1.50 to 1.75 in the blue light emission region (455 nm to 465 nm) or an ordinary refractive index of 1.45 to 1.70 in the 633 nm light wavelength range typically used for measuring refractive index, and is an organic compound with good hole transport properties. It is also possible to obtain an organic compound with high Tg and good reliability. Such organic compounds with hole transport properties have sufficient hole transport properties and can therefore be suitably used as materials for the hole transport layer 112.

[0170] Note that when the second organic compound having a hole-transporting property is used for the hole-injection layer 111, it is preferable to mix a substance having an acceptor property with the organic compound having a hole-transporting property. As the acceptor substance, a compound having an electron-withdrawing group (a halogen group or a 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), and 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyren-2-ylidene)malononitrile. In particular, compounds in which an electron-withdrawing group is bonded to a fused aromatic ring having multiple heteroatoms, such as HAT-CN, are thermally stable and preferred. Radialene derivatives having electron-withdrawing groups (especially halogen groups such as fluoro groups or cyano groups) are also preferred because of their extremely high electron-accepting properties. Specific examples include 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], and α,α',α''-1,2,3-cyclopropanetriylidene tris[2,3,4,5,6-pentafluorobenzeneacetonitrile].

[0171] In addition to the organic compounds described above, other materials with acceptor properties can include molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, and manganese oxide. The hole injection layer 111 can also be formed using phthalocyanine complex compounds such as phthalocyanine (abbreviated as HPc) and copper phthalocyanine (CuPc), aromatic amine compounds such as 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviated as DPAB) and 4,4'-bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (abbreviated as DNTPD), or polymers such as poly(3,4-ethylenedioxythiophene) / poly(styrenesulfonic acid) (PEDOT / PSS). Acceptor materials can extract electrons from the adjacent hole transport layer (or hole transport material) when an electric field is applied.

[0172] When the hole injection layer 111 is formed by mixing the material having hole transport properties with the material having acceptor properties, the material for forming the electrode can be selected regardless of the work function. That is, not only a material having a large work function but also a material having a small work function can be used for the anode 101.

[0173] Next, other examples of the structure and materials of the light-emitting device of one embodiment of the present invention will be described. As described above, the light-emitting device of one embodiment of the present invention includes an EL layer 103 composed of multiple layers between a pair of electrodes, an anode 101 and a cathode 102. The EL layer 103 includes a light-emitting layer 113 containing a light-emitting material and a hole-transport region 120. Note that the hole-transport region 120 has a stacked structure of a low-refractive index layer and a layer containing a monoamine compound having the above structure.

[0174] The anode 101 is preferably formed using a metal, alloy, conductive compound, or mixture thereof having a large work function (specifically, 4.0 eV or higher). Specific examples include indium tin oxide (ITO), indium tin oxide containing silicon or silicon oxide, indium zinc oxide, and indium oxide containing tungsten oxide and zinc oxide (IWZO). These conductive metal oxide films are typically formed by sputtering, but they may also be formed by applying a sol-gel method. For example, indium zinc oxide may be formed by sputtering using a target containing indium oxide and 1 to 20 wt% zinc oxide. Indium oxide containing tungsten oxide and zinc oxide (IWZO) may also be formed by sputtering using a target containing indium oxide and 0.5 to 5 wt% tungsten oxide and 0.1 to 1 wt% zinc oxide. Other examples of materials that can be used for the anode 101 include gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), and nitrides of metal materials (e.g., titanium nitride). Graphene can also be used as the material for the anode 101. By using a composite material (described later) in the layer of the EL layer 103 that is in contact with the anode 101, it becomes possible to select an electrode material regardless of the work function.

[0175] When the anode 101 is made of a material that is transparent to visible light, a light-emitting device that emits light from the cathode side can be formed, as shown in Fig. 1C. When the anode 101 is formed on the substrate side, this light-emitting device can be a so-called bottom-emission type light-emitting device.

[0176] The EL layer 103 preferably has a laminated structure, but the laminated structure is not particularly limited. Various functional layers can be used, such as a hole injection layer, a hole transport layer, an emitting layer, an electron transport layer, an electron injection layer, a carrier blocking layer (hole blocking layer, electron blocking layer), an exciton blocking layer, an intermediate layer, and a charge generation layer. Note that any of these layers may be omitted. In this embodiment, two types of structures are described: a structure having a hole injection layer 111, a hole transport layer 112, an electron transport layer 114, and an electron injection layer 115 in addition to the emitting layer 113, as shown in FIG. 1A; and a structure having a charge generation layer 116 in addition to the electron transport layer 114, the emitting layer 113, the hole injection layer 111, and the hole transport layer 112, as shown in FIG. 1B. The following describes specific materials that can be used to form the functional layers when they are not low-refractive-index layers.

[0177] The 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.

[0178] As the acceptor substance, a compound having an electron-withdrawing group (a halogen group or a 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), and 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyren-2-ylidene)malononitrile. In particular, compounds in which an electron-withdrawing group is bonded to a fused aromatic ring having multiple heteroatoms, such as HAT-CN, are thermally stable and preferred. Radialene derivatives having electron-withdrawing groups (especially halogen groups such as fluoro groups or cyano groups) are also preferred because of their extremely high electron-accepting properties. Specific examples include 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], and α,α',α''-1,2,3-cyclopropanetriylidene tris[2,3,4,5,6-pentafluorobenzeneacetonitrile]. In addition to the organic compounds described above, other materials having acceptor properties can include molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, manganese oxide, etc. The hole injection layer 111 can also be formed from phthalocyanine complex compounds such as phthalocyanine (abbreviated as HPc) and copper phthalocyanine (CuPc), aromatic amine compounds such as 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviated as DPAB) and N,N'-bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviated as 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) when an electric field is applied.

[0179] Furthermore, a composite material in which a material having a hole-transporting property contains the above-mentioned acceptor substance can also be used for the hole-injection layer 111. Note that by using a composite material in which a material having a hole-transporting property contains an acceptor substance, a material for forming an electrode can be selected regardless of the work function. In other words, not only a material with a high work function but also a material with a low work function can be used for the anode 101.

[0180] As a material having hole transport properties to be 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 as a material having hole transport properties to be used in the composite material, -6 cm 2 A substance having a hole mobility of 1 / Vs or more is preferred. Specific examples of organic compounds that can be used as a material having a hole transport property in a composite material are listed below.

[0181] 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), and 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B). Specific examples of the carbazole derivative 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, and Examples of compounds that can be used include tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB), 9-[4-(N-carbazolyl)]phenyl-10-phenylanthracene (abbreviation: CzPA), and 1,4-bis[4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene.Examples of aromatic hydrocarbons 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- Examples of suitable anthracene include 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, and 2,5,8,11-tetra(tert-butyl)perylene. Pentacene and coronene may also be used. Furthermore, it may have a vinyl skeleton. Examples of aromatic hydrocarbons having a vinyl skeleton include 4,4'-bis(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi) and 9,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene (abbreviation: DPVPA).

[0182] In addition, polymer compounds such as poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphenylamine) (abbreviation: PVTPA), poly[N-(4-{N'-[4-(4-diphenylamino)phenyl]phenyl-N'-phenylamino}phenyl)methacrylamide] (abbreviation: PTPDMA), and poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine] (abbreviation: Poly-TPD) can also be used.

[0183] The hole-transporting material used in the composite material preferably has a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, or an anthracene skeleton. In particular, aromatic amines having a substituent containing a dibenzofuran ring or a dibenzothiophene ring, aromatic monoamines having a naphthalene ring, or aromatic monoamines in which a 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group may be used. It is preferable that these organic compounds have an N,N-bis(4-biphenyl)amino group, since this allows the fabrication of light-emitting devices with long lifetimes. Specific examples of such organic compounds 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-i 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 N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP), N-[4-(dibenzothiophen-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)naphthyl-2-yltriphenylamine (abbreviation: BBAPβNB-03), 4,4'-diphenyl-4''-(6;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B), 4,4'-diphenyl-4''-(7;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B-03), 4,4'-diphenyl-4''-(4;2'-binaphthyl-1-yl)triphenylamine (abbreviation: BBAβNαNB), 4,4'-diphenyl-4''-(5;2'- (binaphthyl-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 nylamine (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-[4'-(carbazol-9-yl)biphenyl-4-yl]-4'-(2-naphthyl)-4''-phenyl 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([1,1'-biphenyl]-4-yl)-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-fluoren)-4-amine (abbreviated as oFBiSF), N-(4-biphenyl)-N-(9,9-dimethyl-9H-fluoren-2-yl)dibenzofuran-4-amine (abbreviated as FrBiF), N-[4-(1-naphthyl)phenyl]-N-[3-(6-phenyldibenzofuran-4-yl)phenyl]-1-naphthylamine (abbreviated as mPDBfBNBN), 4-phenyl-4'-(9-phenylfluoren-9-yl)trimethylamine triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-phenyl-4'-[4-(9-phenylfluoren-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 (abbreviated as PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBNBB), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviated as PCBASF), N-(1,1'-biphenyl-4-yl)-9,9-dimethyl-N-[4-(9-phenyl-9H- carbazol-3-yl)phenyl]-9H-fluoren-2-amine (abbreviation: PCBBiF), N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-4-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-3-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-2-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-2-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,Examples include 9'-spirobi-9H-fluorene-1-amine.

[0184] Note that the material having hole-transporting properties used in the composite material is more preferably a substance having a relatively deep HOMO level of -5.7 eV or more and -5.4 eV or less. When the material having hole-transporting properties used in the composite material has a relatively deep HOMO level, injection of holes into the hole-transport layer 112 becomes easy, and a light-emitting device with a long lifetime can be easily obtained. Furthermore, when the material having hole-transporting properties used in the composite material has a relatively deep HOMO level, hole induction is appropriately suppressed, and a light-emitting device with a long lifetime can be obtained.

[0185] The refractive index of the layer can be reduced by further mixing an alkali metal or alkaline earth metal fluoride into the composite material (preferably with an atomic ratio of fluorine atoms of 20% or more in the layer), which also allows a layer with a low refractive index to be formed inside the EL layer 103, thereby improving the external quantum efficiency of the light-emitting device.

[0186] By forming the hole injection layer 111, the hole injection property becomes good, and a light emitting device with a low driving voltage can be obtained.

[0187] Among substances having acceptor properties, organic compounds having acceptor properties are easy to use because they can be easily vapor-deposited and formed into a film.

[0188] The hole transport layer 112 is formed by including a material having a hole transport property. -6 cm 2 It is preferable that the hole mobility is / Vs or more.

[0189] Examples of the material having hole transport properties 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: BPA), and 4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB). FLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviated as mBPAFLP), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCB Aromatic amines such as 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviated as PCBAF), and N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviated as PCBASF) Compounds with a benzophenone skeleton, compounds with a carbazole skeleton such as 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), and 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), and compounds with a benzophenone skeleton such as 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,Examples of suitable compounds include 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 preferred because they have good reliability, high hole transport properties, and contribute to reducing driving voltage. Note that the substances listed as materials having hole transport properties used in the composite material of the hole injection layer 111 can also be suitably used as materials for forming the hole transport layer 112.

[0190] The light-emitting layer 113 contains a light-emitting substance and a host material. The light-emitting layer 113 may also contain other materials. Alternatively, the light-emitting layer 113 may be a laminate of two layers with different compositions.

[0191] The light-emitting substance may be a fluorescent substance, a phosphorescent substance, a substance that exhibits thermally activated delayed fluorescence (TADF), or other light-emitting substances. Note that one embodiment of the present invention is more preferably applicable to the case where the light-emitting layer 113 is a layer that exhibits fluorescent light, particularly a layer that exhibits blue fluorescent light.

[0192] Examples of materials that can be used as the fluorescent substance in the light-emitting layer 113 include the following: Other fluorescent substances can also be used.

[0193] 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 )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-carbazol-3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetra-tert-butylperylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), N,N''-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene)bis[N,N',N'-triphenyl-1,4-phenylenediamine] (abbreviation: DPABPA), N,9 -diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine (abbreviated as 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviated as 2DPAPPA), N,N,N',N',N'',N'',N''',N'''-octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviated as DBC1), Coumarin 30, N-(9,10-diphenyl-2-anthryl)-N,9-Diphenyl-9H-carbazol-3-amine (abbreviation: 2PCAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCABPhA), N-(9,10-diphenyl-2-anthryl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAB PhA), 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 amine (abbreviation: p-mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB),6-Bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDCM), 2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJTM), N,N'-diphenyl-N,N'-(1,6-pyren-diyl)bis[(6-phenylbenzo[b ]naphtho[1,2-d]furan)-8-amine] (abbreviated as 1,6BnfAPrn-03), 3,10-bis[N-(9-phenyl-9H-carbazol-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviated as 3,10PCA2Nbf(IV)-02), and 3,10-bis[N-(dibenzofuran-3-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviated as 3,10FrA2Nbf(IV)-02). In particular, condensed aromatic diamine compounds, such as pyrenediamine compounds, such as 1,6FLPAPrn, 1,6mMemFLPAPrn, and 1,6BnfAPrn-03, are preferred because of their high hole-trapping properties, excellent luminous efficiency, and reliability.

[0194] When a phosphorescent material is used as the light-emitting material in the light-emitting layer 113, examples of materials that can be used include the following.

[0195] Organometallic iridium complexes with 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) (abbreviated as [Ir(mpptz-dmp)3]), tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III) (abbreviated as [Ir(Mptz)3]), and tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviated as [Ir(iPrptz-3b)3]), and tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III) Organometallic iridium complexes with a 1H-triazole skeleton, such as tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Mptz1-mp)3]) and tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Prptz1-Me)3]), organometallic iridium complexes with an imidazole skeleton, such as fac-tris[(1-2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviation: [Ir(iPrpmi)3]) and tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: [Ir(dmpimpt-Me)3]), and bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]iridium(III) tetrakis(1-pyrazolyl)borate (abbreviation: FIr6), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]iridium(III) picolinate (abbreviation: FIrpic), bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinato-N,C 2’}iridium(III) picolinate (abbreviation: [Ir(CF3ppy)2(pic)]), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’] Organometallic iridium complexes with phenylpyridine derivatives bearing electron-withdrawing groups as ligands, such as iridium(III) acetylacetonate (abbreviated as FIracac), are compounds that exhibit blue phosphorescence, with peak emission in the wavelength range from 440 nm to 520 nm.

[0196] 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-( Organometallic iridium complexes with a pyrimidine skeleton, such as (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(mpmppm)2(acac)]) and (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm)2(acac)]), organometallic iridium complexes with a pyrazine skeleton, such as (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-Me)2(acac)]) and (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-iPr)2(acac)]), and 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’ Examples include organometallic iridium complexes with a pyridine skeleton, such as iridium(III) acetylacetonate (abbreviated as [Ir(pq)2(acac)]), and rare earth metal complexes, such as tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviated as [Tb(acac)3(Phen)]). These compounds primarily exhibit green phosphorescence, with an emission peak in the wavelength range of 500 to 600 nm. Organometallic iridium complexes with a pyrimidine skeleton are particularly preferred, as they are remarkably superior in reliability and luminous efficiency.

[0197] 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)]), and bis[4,6-di(naphthalen-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(d1npm)2(dpm)]), Organometallic iridium complexes with 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)]), and (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: [Ir(Fdpq)2(acac)]), and tris(1-phenylisoquinolinato-N,C 2’ ) Iridium(III) (abbreviation: [Ir(piq)3]), bis(1-phenylisoquinolinato-N,C 2’ Examples include organometallic iridium complexes with a pyridine skeleton, such as iridium(III) acetylacetonate (abbreviated as [Ir(piq)2(acac)]), platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrinplatinum(II) (abbreviated as PtOEP), and rare earth metal complexes such as tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III) (abbreviated as [Eu(DBM)3(Phen)]) and tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III) (abbreviated as [Eu(TTA)3(Phen)]). These compounds exhibit red phosphorescence, with peak emission in the wavelength range of 600 to 700 nm. Furthermore, organometallic iridium complexes having a pyrazine skeleton can emit red light with good chromaticity.

[0198] In addition to the phosphorescent compounds described above, known phosphorescent compounds may be selected and used.

[0199] TADF materials include fullerene and its derivatives, acridine and its derivatives, eosin derivatives, etc. Also available are metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd). Examples of the metal-containing porphyrin include protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF2(OEP)), etioporphyrin-tin fluoride complex (SnF2(Etio I)), and octaethylporphyrin-platinum chloride complex (PtCl2OEP), all of which are shown in the following structural formulas.

[0200] [ka]

[0201] In addition, 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), 9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCzPTzn), 2-[4-(10H-phenoxazin-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: P Heterocyclic compounds having either or both of a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring, such as 3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), and 10-phenyl-10H,10'H-spiro[acridine-9,9'-anthracene]-10'-one (abbreviation: ACRSA), can also be used. The heterocyclic compound has a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring, and therefore has high electron transport and hole transport properties, and is therefore preferred. Among the skeletons having a π-electron-deficient heteroaromatic ring, pyridine skeleton, diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), and triazine skeleton are preferred because they are stable and reliable. In particular, benzofuropyrimidine skeleton, benzothienopyrimidine skeleton, benzofuropyrazine skeleton, and benzothienopyrazine skeleton are preferred because they have high acceptor properties and good reliability. Furthermore, among the skeletons having a π-electron-rich heteroaromatic ring, acridine skeleton, phenoxazine skeleton, phenothiazine skeleton, furan skeleton, thiophene skeleton, and pyrrole skeleton are preferred because they are stable and reliable.The furan skeleton is preferably a dibenzofuran skeleton, and the thiophene skeleton is preferably a dibenzothiophene skeleton. The pyrrole skeleton is particularly preferably an indole skeleton, a carbazole skeleton, an indolocarbazole skeleton, a bicarbazole skeleton, or a 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole skeleton. Substances in which a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded are particularly preferred because the electron-donating ability of the π-electron-rich heteroaromatic ring and the electron-accepting ability of the π-electron-deficient heteroaromatic ring are both enhanced, thereby reducing the energy difference between the S1 level and the T1 level, thereby enabling efficient thermally activated delayed fluorescence. Instead of the π-electron-deficient heteroaromatic ring, an aromatic ring bonded to an electron-withdrawing group such as a cyano group may be used. The π-electron-rich skeleton may be, for example, an aromatic amine skeleton or a phenazine skeleton. Examples of usable π-electron-deficient skeletons include 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 or boranthrene, an aromatic ring or 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. In this way, a π-electron-deficient skeleton or a π-electron-rich skeleton can be used in place of at least one of a π-electron-deficient heteroaromatic ring and a π-electron-rich heteroaromatic ring.

[0202] [ka]

[0203] TADF materials are materials with a small difference between the S1 and T1 levels, and have the ability to convert triplet excitation energy to singlet excitation energy through reverse intersystem crossing. Therefore, triplet excitation energy can be upconverted to singlet excitation energy (reverse intersystem crossing) using a small amount of thermal energy, allowing for efficient generation of a singlet excited state. Triplet excitation energy can also be converted into light emission.

[0204] Furthermore, exciplexes (also known as exciplexes), which form an excited state with two types of substances, have an extremely small difference between the S1 and T1 levels and function as TADF materials that can convert triplet excitation energy into singlet excitation energy.

[0205] The phosphorescence spectrum observed at low temperatures (for example, 77 K to 10 K) can be used as an indicator of the T1 level. For a TADF material, when a tangent line is drawn at the base of the fluorescence spectrum on the short wavelength side and the energy of the wavelength of the extrapolated line is defined as the S1 level, and a tangent line is drawn at the base of the phosphorescence spectrum on the short wavelength side and the energy of the wavelength of the extrapolated line is defined as the T1 level, the difference between S1 and T1 is preferably 0.3 eV or less, and more preferably 0.2 eV or less.

[0206] When a TADF material is used as a light-emitting material, the S1 level of the host material is preferably higher than the S1 level of the TADF material, and the T1 level of the host material is preferably higher than the T1 level of the TADF material.

[0207] As the host material of the light-emitting layer, various carrier transporting materials such as a material having an electron transporting property, a material having a hole transporting property, or the above-mentioned TADF material can be used.

[0208] As a material having hole transport properties, an organic compound having an amine skeleton or a π-electron-rich heteroaromatic ring skeleton is preferable. 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'-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP ... mBPAFLP), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (PCBANB), 4, Aromatic amine skeletons such as 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]fluoren-2-amine (abbreviation: PCBAF), and N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF) and compounds with a carbazole skeleton such as 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), and 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), as well as 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,Examples of suitable materials include 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 preferred because they have good reliability, high hole transport properties, and contribute to reducing driving voltage. The organic compounds listed as examples of materials having hole transport properties for the hole transport layer 112 can also be used. ,

[0209] Examples of materials having electron transport properties include 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), and bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ), as well as organic compounds having a π-electron-deficient heteroaromatic ring skeleton. Examples of organic compounds having a π-electron-deficient heteroaromatic ring skeleton include 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-oxadiazole] (abbreviation: 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,2,4-triazole] ... [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-1 Heterocyclic compounds with polyazole skeletons such as H-benzimidazole (abbreviated as mDBTBIm-II), 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviated as 2mDBTPDBq-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviated as 2mDBTBPDBq-II), and 2-[3' Heterocyclic compounds with diazine skeletons such as 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), and 3,Heterocyclic compounds with a pyridine skeleton, such as 5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy) and 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)-1,1'-biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn), 2-[(1,1'-biphenyl)-4-yl]-4-phenyl-6-[9,9'-spirobi(9 Examples of heterocyclic compounds having a triazine skeleton include 2-{3-[3-(benzo"b"naphtho[1,2-d]furan-8-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn), and 2-{3-[3-(benzo"b"naphtho[1,2-d]furan-6-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn-02). Among the above, heterocyclic compounds having a diazine skeleton, heterocyclic compounds having a pyridine skeleton, and heterocyclic compounds having a triazine skeleton are preferred because of their high reliability. In particular, heterocyclic compounds having a diazine (pyrimidine or pyrazine) skeleton and heterocyclic compounds having a triazine skeleton have high electron transport properties and contribute to reducing driving voltage.

[0210] The TADF materials that can be used as host materials are the same as those listed above. When a TADF material is used as a host material, the triplet excitation energy generated in the TADF material is converted to singlet excitation energy through reverse intersystem crossing, and the energy is then transferred to the light-emitting material, thereby improving the luminous efficiency of the light-emitting device. In this case, the TADF material functions as an energy donor, and the light-emitting material functions as an energy acceptor.

[0211] This is very effective when the luminescent material is a fluorescent luminescent material. In this case, in order to obtain high luminous efficiency, the S1 level of the TADF material is preferably higher than the S1 level of the fluorescent luminescent material. In addition, the T1 level of the TADF material is preferably higher than the S1 level of the fluorescent luminescent material. Therefore, the T1 level of the TADF material is preferably higher than the T1 level of the fluorescent luminescent material.

[0212] It is also preferable to use a TADF material that emits light that overlaps with the wavelength of the lowest-energy absorption band of the fluorescent material, as this allows for smooth transfer of excitation energy from the TADF material to the fluorescent material, resulting in efficient light emission.

[0213] Furthermore, to efficiently generate singlet excitation energy from triplet excitation energy through reverse intersystem crossing, carrier recombination is preferred in the TADF material. It is also preferable that the triplet excitation energy generated in the TADF material does not transfer to triplet excitation energy in the fluorescent material. To achieve this, the fluorescent material preferably has a protecting group around the luminophore (the skeleton responsible for light emission) of the fluorescent material. The protecting group is preferably a substituent without a π bond, and is preferably a saturated hydrocarbon. Specific examples include alkyl groups with 3 to 10 carbon atoms, substituted or unsubstituted cycloalkyl groups with 3 to 10 carbon atoms, and trialkylsilyl groups with 3 to 10 carbon atoms. Multiple protecting groups are even more preferred. Substituents without a π bond have poor carrier transport properties, allowing for the distance between the TADF material and the luminophore of the fluorescent material to be increased without significantly affecting carrier transport or carrier recombination. Here, the term "luminophore" refers to the atomic group (skeleton) responsible for light emission in the fluorescent material. The luminophore preferably has a skeleton having a π bond, preferably contains an aromatic ring, and preferably has a fused aromatic ring or a fused heteroaromatic ring. Examples of the fused aromatic ring or the fused 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, or a naphthobisbenzofuran skeleton are preferred because of their high fluorescence quantum yield.

[0214] When a fluorescent emitting substance is used as the emitting substance, a material having an anthracene skeleton is suitable as the host material. Using a substance having an anthracene skeleton as the host material for a fluorescent emitting substance makes it possible to realize an emitting layer with both excellent luminous efficiency and durability. As a substance having an anthracene skeleton to be used as a host material, a diphenylanthracene skeleton, particularly a 9,10-diphenylanthracene skeleton, is preferred due to its chemical stability. Furthermore, host materials having a carbazole skeleton are preferred because of their enhanced hole injection and transport properties. However, host materials containing a benzocarbazole skeleton, in which a benzene ring is further condensed to carbazole, are even more preferred because their HOMO is approximately 0.1 eV shallower than that of carbazole, facilitating hole insertion. In particular, host materials containing a dibenzocarbazole skeleton are preferred because their HOMO is approximately 0.1 eV shallower than that of carbazole, facilitating hole insertion, and also exhibiting excellent hole transport properties and high heat resistance. Therefore, a more preferable host material is a substance having both a 9,10-diphenylanthracene skeleton and a carbazole skeleton (or a benzocarbazole skeleton or a dibenzocarbazole skeleton). From the viewpoint of the hole injection / transport property, a benzofluorene skeleton or a dibenzofluorene skeleton may be used instead of the carbazole skeleton. Examples of such a substance 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-(N-carbazolyl)]phenyl-10-phenylanthracene (abbreviation: CzPA), and 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazo. Examples include anthracene (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), and 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: αN-βNPAnth).In particular, CzPA, cgDBCzPA2mBnfPPA, and PCzPA are preferable choices because they exhibit very good properties.

[0215] The host material may be a mixture of multiple substances, and when a mixture of host materials is used, it is preferable to mix a material having electron-transporting properties with a material having hole-transporting properties. By mixing a material having electron-transporting properties with 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 1:19 to 19:1 (material having hole-transporting properties:material having electron-transporting properties).

[0216] A phosphorescent material can be used as part of the mixed material. The phosphorescent material can be used as an energy donor that provides excitation energy to a fluorescent material when the fluorescent material is used as a light-emitting material.

[0217] Furthermore, these mixed materials may form an exciplex. It is preferable to select a combination that forms an exciplex that emits light that overlaps with the wavelength of the lowest-energy absorption band of the light-emitting material, because this allows for smooth energy transfer and efficient light emission. Furthermore, using this structure is also preferable because it reduces the driving voltage.

[0218] At least one of the materials forming the exciplex may be a phosphorescent material, which allows efficient conversion of triplet excitation energy into singlet excitation energy through reverse intersystem crossing.

[0219] 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. It is also preferable that the LUMO level of the hole-transporting material is equal to or higher than the LUMO level of the electron-transporting material. The LUMO and HOMO levels of the materials can be derived from the electrochemical properties (reduction potential and oxidation potential) of the materials measured by cyclic voltammetry (CV).

[0220] The formation of exciplexes can be confirmed by, for example, comparing the emission spectra of a hole-transporting material, an electron-transporting material, and a mixed film of these materials and observing the phenomenon that the emission spectrum of the mixed film is shifted to longer wavelengths than the emission spectra of each material (or has a new peak at longer wavelengths). Alternatively, it can be confirmed by comparing the transient photoluminescence (PL) of a hole-transporting material, the transient PL of an electron-transporting material, and a mixed film of these materials and observing differences in transient response, such as the transient PL lifetime of the mixed film having a longer-lived component or a larger proportion of delayed components than the transient PL lifetimes of the individual materials. The above-mentioned transient PL can also be interpreted as transient electroluminescence (EL). In other words, the formation of exciplexes can also be confirmed by comparing the transient EL of a hole-transporting material, the transient EL of an electron-transporting material, and a mixed film of these materials and observing differences in transient response.

[0221] The electron-transporting layer 114 is a layer containing a substance having an electron-transporting property. As the substance having an electron-transporting property, any of the substances having an electron-transporting property that can be used as the host material can be used.

[0222] The electron transport layer 114 has an electron mobility of 1×10 when the square root of the electric field strength [V / cm] is 600. -7 cm 2 / Vs or more 5×10 -5 cm 2 / Vs or less. By reducing the electron transport property of 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 becoming electron-excessive. This configuration is particularly preferable because it improves the lifetime when the hole-injection layer is formed of a composite material and the HOMO level of the material having hole-transport properties in the composite material is a substance having a relatively deep HOMO level of -5.7 eV or more and -5.4 eV or less. In this case, the HOMO level of the material having electron-transport properties is preferably -6.0 eV or more.

[0223] In addition, it is preferable that the alkali metal or the metal complex of the alkali metal in the electron transport layer 114 has a concentration difference (including a case where the difference is 0) in the thickness direction.

[0224] Between the electron transport layer 114 and the cathode 102, a layer containing an alkali metal or alkaline earth metal, such as lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF), or 8-quinolinolato-lithium (abbreviated as Liq), or a compound or complex thereof, may be provided as the electron injection layer 115. The electron injection layer 115 may be a layer made of a substance having electron transport properties containing an alkali metal or alkaline earth metal or a compound thereof, or an electride. Examples of the electride include a substance in which a high concentration of electrons is added to a mixed oxide of calcium and aluminum.

[0225] Note that a layer containing a fluoride of the alkali metal or alkaline earth metal in a concentration (50 wt % or more) sufficient to form a microcrystalline state in a substance having an electron transport property (preferably an organic compound having a bipyridine skeleton) can also be used as the electron-injection layer 115. Since this layer has a low refractive index, it is possible to provide a light-emitting device with better external quantum efficiency.

[0226] Furthermore, a charge generation layer 116 may be provided instead of the electron injection layer 115 of FIG. 1A (FIG. 1B). The charge generation layer 116 is a layer that can inject holes into a layer in contact with the cathode side of the layer and electrons into a layer in contact with the anode side of the layer 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 above as a material that can form the hole injection layer 111. The P-type layer 117 may also be formed by laminating a film containing an acceptor material and a film containing a hole transport material, both of which are materials that form 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 cathode 102, and the light-emitting device operates.

[0227] It is preferable that the charge generating layer 116 be 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 .

[0228] The electron relay layer 118 contains at least a substance having electron transport properties and has the function of preventing 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 transport 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 of the electron transport layer 114 that is in contact with the charge generation layer 116. The specific energy level of the LUMO level of the substance having electron transport properties used in the electron relay layer 118 is −5.0 eV or higher, preferably −5.0 eV or higher and −3.0 eV or lower. Note that the substance having electron transport properties used in the electron relay layer 118 is preferably a phthalocyanine-based material or a metal complex having a metal-oxygen bond and an aromatic ligand.

[0229] The electron injection buffer layer 119 can be made of a material with high electron injection properties, such as alkali metals, alkaline earth metals, rare earth metals, and compounds thereof (alkali metal compounds (including oxides such as lithium oxide, halides, and carbonates such as lithium carbonate and cesium carbonate), alkaline earth metal compounds (including oxides, halides, and carbonates), or rare earth metal compounds (including oxides, halides, and carbonates)).

[0230] Furthermore, when the electron injection buffer layer 119 is formed to contain a substance having electron transport properties and a donor substance, examples of the donor substance that can be used include alkali metals, alkaline earth metals, rare earth metals, and compounds thereof (alkali metal compounds (including oxides such as lithium oxide, halides, and carbonates such as lithium carbonate and cesium carbonate), alkaline earth metal compounds (including oxides, halides, and carbonates), and rare earth metal compounds (including oxides, halides, and carbonates)), as well as organic compounds such as tetrathianaphthacene (abbreviation: TTN), nickelocene, and decamethylnickelocene.

[0231] The substance having an electron-transporting property can be formed using the same material as the material for forming the electron-transporting layer 114 described above. Since the material is an organic compound with a low refractive index, by using the material for the electron-injection buffer layer 119, a light-emitting device with good external quantum efficiency can be obtained.

[0232] Materials that can be used to form the cathode 102 include metals, alloys, electrically conductive compounds, and mixtures thereof that have a low work function (specifically, 3.8 eV or less). 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), 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 cathode 102 and the electron transport layer, various conductive materials can be used for the cathode 102, regardless of the magnitude of the work function, such as Al, Ag, ITO, and indium oxide-tin oxide containing silicon or silicon oxide.

[0233] When the cathode 102 is made of a material that is transparent to visible light, a light-emitting device that emits light from the cathode side can be formed, as shown in Fig. 1D. When the anode 101 is formed on the substrate side, this light-emitting device can be a so-called top-emission type light-emitting device.

[0234] These conductive materials can be formed into films by dry methods such as vacuum deposition and sputtering, inkjet methods, spin coating methods, etc. Alternatively, they may be formed by wet methods using a sol-gel method, or by wet methods using a paste of a metal material.

[0235] In addition, various methods, whether dry or wet, can be used to form the EL layer 103. For example, vacuum deposition, gravure printing, offset printing, screen printing, inkjet printing, or spin coating may be used.

[0236] Furthermore, the above-mentioned electrodes or layers may be formed using different film formation methods.

[0237] The configuration of the layer provided between the anode 101 and the cathode 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 location away from the anode 101 and the cathode 102 is preferable, so as to suppress quenching caused by the proximity of the light-emitting region to the metals used in the electrodes and the carrier injection layer.

[0238] Furthermore, the hole transport layer and 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 light-emitting material contained in the light-emitting layer, in order to suppress energy transfer from excitons generated in the light-emitting layer.

[0239] Next, an embodiment of a light-emitting device (also called a stacked element or tandem element) having a configuration in which multiple light-emitting units are stacked will be described. This light-emitting device has multiple light-emitting units between an anode and a cathode. One light-emitting unit has a configuration substantially similar to that of the EL layer 103 shown in FIG. 1A. In other words, a tandem element is a light-emitting device having multiple light-emitting units, and the light-emitting device shown in FIG. 1A or 1B can be said to be a light-emitting device having one light-emitting unit.

[0240] In a tandem element, a first light-emitting unit and a second light-emitting unit are stacked between an anode and a cathode, and a charge generation layer is provided between the first light-emitting unit and the second light-emitting unit. The anode and cathode correspond to anode 101 and cathode 102 in FIG. 1A, respectively, and the same as those described in the description of FIG. 1A can be applied. Furthermore, the first light-emitting unit and the second light-emitting unit may have the same or different configurations.

[0241] The charge generation layer in a tandem element has the function of injecting electrons into one light-emitting unit and injecting holes into the other light-emitting unit when a voltage is applied between the anode and the cathode. That is, when a voltage is applied so that the potential of the anode is higher than the potential of the cathode, the charge generation layer may inject electrons into the first light-emitting unit and inject holes into the second light-emitting unit.

[0242] The charge generation layer is preferably formed to have the same structure as the charge generation layer 116 described in FIG. 1B. A composite material of an organic compound and a metal oxide has excellent carrier injection and carrier transport properties, and therefore can achieve low-voltage driving and low-current driving. Note that when the anode side surface of the light-emitting unit is in contact with the charge generation layer, the charge generation layer can also serve as the hole injection layer of the light-emitting unit, and therefore the light-emitting unit does not need to be provided with a hole injection layer.

[0243] Furthermore, when the electron injection buffer layer 119 is provided in the charge generation layer of a tandem element, the electron injection buffer layer 119 plays the role of an electron injection layer in the light-emitting unit on the anode side, and therefore it is not necessarily required to form an electron injection layer in the light-emitting unit on the anode side.

[0244] While the above describes a tandem element having two light-emitting units, the same can be applied to a tandem element having three or more stacked light-emitting units. By arranging multiple light-emitting units between a pair of electrodes and separating them with a charge-generating layer, it is possible to achieve a device that emits high-intensity light while maintaining a low current density, and that has a long lifespan. It is also possible to realize a light-emitting device that can be driven at a low voltage and consumes little power.

[0245] Furthermore, by making each light-emitting unit emit a different light color, the light-emitting device as a whole can emit light of a desired color. For example, in a light-emitting device having two light-emitting units, it is possible to obtain a light-emitting device that emits white light as a whole by obtaining red and green light from the first light-emitting unit and blue light from the second light-emitting unit.

[0246] The above-described EL layer 103, the first light-emitting unit, the second light-emitting unit, the charge generation layer, and other layers and electrodes can be formed by, for example, vapor deposition (including vacuum deposition), droplet discharge (also called ink-jet method), coating, gravure printing, etc. They may also contain low-molecular-weight materials, medium-molecular-weight materials (including oligomers and dendrimers), or polymer materials.

[0247] This embodiment mode can be freely combined with other embodiment modes.

[0248] (Embodiment 2) In this embodiment, a light-emitting apparatus using the light-emitting device described in Embodiment 1 will be described.

[0249] In this embodiment, a light-emitting device manufactured using the light-emitting device described in Embodiment 1 will be described with reference to FIGS. 2A and 2B. FIG. 2A is a top view showing the light-emitting device, and FIG. 2B is a cross-sectional view taken along dashed lines AB and CD shown in FIG. 2A. This light-emitting device includes a driver circuit section (source line driver circuit) 601, a pixel section 602, and a driver circuit section (gate line driver circuit) 603, all of which are shown by dotted lines, to control light emission from the light-emitting device. Also, 604 denotes a sealing substrate, 605 denotes a sealant, and the inside surrounded by the sealant 605 forms a space 607.

[0250] The routing wiring 608 is wiring for transmitting signals input to the source line driver circuit 601 and the gate line driver circuit 603, and receives video signals, clock signals, start signals, reset signals, etc. from an FPC (flexible printed circuit) 609, which serves as an external input terminal. Although only the FPC is shown here, a printed wiring board (PWB) may be attached to this FPC. In this specification, the light-emitting device includes not only the light-emitting device itself, but also a state in which an FPC or PWB is attached to it.

[0251] Next, the cross-sectional structure will be described with reference to Fig. 2B. A driver circuit section and a pixel section are formed on an element substrate 610, but here, a source line driver circuit 601, which is the driver circuit section, and one pixel in a pixel section 602 are shown.

[0252] The element substrate 610 may be made of a substrate made of glass, quartz, organic resin, metal, alloy, semiconductor, or a plastic substrate made of FRP (Fiber Reinforced Plastics), PVF (Polyvinyl Fluoride), polyester, acrylic resin, or the like.

[0253] The structure of the transistors used in the pixels and driver circuits is not particularly limited. For example, they may be inverted staggered transistors or staggered transistors. Furthermore, they may be top-gate or bottom-gate transistors. The semiconductor material used for the transistors is not particularly limited, and examples thereof include silicon, germanium, silicon carbide, and gallium nitride. 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.

[0254] The crystallinity of a semiconductor material used for a transistor is not particularly limited, and any of an amorphous semiconductor and a crystalline semiconductor (a microcrystalline semiconductor, a polycrystalline semiconductor, a single crystal semiconductor, or a semiconductor having a crystalline region in part) may be used. The use of a crystalline semiconductor is preferable because it can suppress deterioration of transistor characteristics.

[0255] Here, it is preferable to use an oxide semiconductor for semiconductor devices such as transistors provided in the pixels and driver circuits, as well as transistors used in touch sensors, which will be described later. In particular, it is preferable to use an oxide semiconductor having a wider band gap than silicon. By using an oxide semiconductor having a wider band gap than silicon, the current in the off state of the transistor can be reduced.

[0256] The oxide semiconductor preferably contains at least indium (In) or zinc (Zn), and more preferably contains an oxide represented by In-M-Zn oxide (M is a metal such as Al, Ti, Ga, Ge, Y, Zr, Sn, La, Ce, or Hf).

[0257] In particular, it is preferable to use, as the semiconductor layer, an oxide semiconductor film having a plurality of crystal parts whose c-axes are oriented perpendicular to the surface on which the semiconductor layer is formed or the top surface of the semiconductor layer and which does not have grain boundaries between adjacent crystal parts.

[0258] By using such a material for the semiconductor layer, fluctuations in electrical characteristics are suppressed, and a highly reliable transistor can be realized.

[0259] Furthermore, a transistor having the above-described semiconductor layer can retain charge stored in a capacitor through the transistor for a long period of time due to its low off-state current. By applying such a transistor to a pixel, it is possible to stop the driver circuit while maintaining the gray level of an image displayed in each display region. As a result, an electronic device with extremely low power consumption can be realized.

[0260] To stabilize the characteristics of the transistor, it is preferable to provide an underlayer film. The underlayer film can be formed as a single layer or a multilayer using an inorganic insulating film such as a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a silicon nitride oxide film. The underlayer film can be formed by a sputtering method, a CVD (Chemical Vapor Deposition) method (such as a plasma CVD method, a thermal CVD method, or a MOCVD (Metal Organic CVD) method), an ALD (Atomic Layer Deposition) method, a coating method, a printing method, or the like. Note that the underlayer film need not be provided if it is not necessary.

[0261] Note that FET 623 represents one of the transistors formed in the drive circuit section 601. The drive circuit may be formed of various CMOS circuits, PMOS circuits, or NMOS circuits. In addition, although this embodiment shows a driver-integrated type in which the drive circuit is formed on a substrate, this is not necessarily required, and the drive circuit may also be formed externally rather than on the substrate.

[0262] Furthermore, the pixel section 602 is formed by a plurality of pixels each including a switching FET 611, a current control FET 612, and an anode 613 electrically connected to the drain of the FET, but is not limited to this, and the pixel section may be formed by combining three or more FETs and a capacitance element.

[0263] An insulator 614 is formed to cover the end of the anode 613. Here, it can be formed by using a positive photosensitive acrylic resin film.

[0264] Furthermore, in order to improve the coverage of an EL layer or the like to be formed later, a curved surface having a curvature is formed at the upper or lower end of the insulator 614. For example, when a positive photosensitive acrylic resin is used as the material for the insulator 614, it is preferable that only the upper end of the insulator 614 has a curved surface having a radius of curvature (0.2 μm to 3 μm). Furthermore, either a negative photosensitive resin or a positive photosensitive resin can be used as the insulator 614.

[0265] An EL layer 616 and a cathode 617 are formed on the anode 613. It is desirable to use a material with a large work function for the anode 613. For example, a single layer film such as an ITO film, an indium tin oxide film containing silicon, an indium oxide film containing 2 to 20 wt % zinc oxide, a titanium nitride film, a chromium film, a tungsten film, a Zn film, or a Pt film can be used. It is also possible to use a laminated structure of a titanium nitride film and a film mainly composed of aluminum, or a three-layer structure of a titanium nitride film, a film mainly composed of aluminum, and a titanium nitride film. The laminated structure provides low resistance as wiring, good ohmic contact, and the anode can function well.

[0266] The EL layer 616 is formed by various methods such as a vapor deposition method using a vapor deposition mask, an inkjet method, or a spin coating method. The EL layer 616 includes the components described in Embodiment 1. Other materials constituting the EL layer 616 may be low-molecular compounds or high-molecular compounds (including oligomers and dendrimers).

[0267] Furthermore, it is preferable to use a material with a small work function (Al, Mg, Li, Ca, or alloys or compounds thereof (MgAg, MgIn, AlLi, etc.)) as a material formed on the EL layer 616. When light generated in the EL layer 616 is transmitted through the cathode 617, it is preferable to use a laminate of a thin metal thin film and a transparent conductive film (ITO, indium oxide containing 2 to 20 wt % zinc oxide, indium tin oxide containing silicon, zinc oxide (ZnO), etc.) as the cathode 617.

[0268] Note that a light-emitting device is formed with the anode 613, the EL layer 616, and the cathode 617. The light-emitting device is the light-emitting device described in Embodiment 1. Note that a pixel portion is formed with a plurality of light-emitting devices, but the light-emitting device in this embodiment may include both the light-emitting device described in Embodiment 1 and light-emitting devices having other structures.

[0269] Furthermore, by bonding the sealing substrate 604 to the element substrate 610 with a sealant 605, a structure is formed in which a light-emitting device 618 is provided in a space 607 surrounded by the element substrate 610, the sealing substrate 604, and the sealant 605. The space 607 is filled with a filler, which may be filled with an inert gas (nitrogen, argon, etc.) or a sealant. A recess is formed in the sealing substrate and a desiccant is provided therein, which is a preferable configuration because it can suppress deterioration due to the influence of moisture.

[0270] It is preferable to use epoxy resin or glass frit for the sealing material 605. It is also desirable that these materials are as moisture and oxygen impermeable as possible. In addition to glass and quartz substrates, plastic substrates made of FRP (Fiber Reinforced Plastics), PVF (Polyvinyl Fluoride), polyester, acrylic resin, etc. can be used for the sealing substrate 604.

[0271] Although not shown in Figures 2A and 2B, a protective film may be provided on the cathode. The protective film may be formed of an organic resin film or an inorganic insulating film. The protective film may also be formed so as to cover the exposed portion of the sealing material 605. The protective film may also be provided so as to cover the surfaces and side surfaces of the pair of substrates, the exposed side surfaces of the sealing layer, the insulating layer, etc.

[0272] The protective film can be made of a material that is impermeable to impurities such as water, and therefore can effectively prevent impurities such as water from diffusing from the outside to the inside.

[0273] The protective film may be made of an oxide, a nitride, a fluoride, a sulfide, a ternary compound, a metal, a polymer, or the like. For example, a material 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, indium oxide, or the like; a material containing aluminum nitride, hafnium nitride, silicon nitride, tantalum nitride, titanium nitride, niobium nitride, molybdenum nitride, zirconium nitride, gallium nitride, or the like; a nitride containing titanium and aluminum; an oxide containing titanium and aluminum; an oxide containing aluminum and zinc; a sulfide containing manganese and zinc; a sulfide containing cerium and strontium; an oxide containing erbium and aluminum; or an oxide containing yttrium and zirconium.

[0274] The protective film is preferably formed using a film formation method that provides good step coverage. One such method is atomic layer deposition (ALD). It is preferable to use a material that can be formed using the ALD method for the protective film. By using the ALD method, it is possible to form a dense protective film with reduced defects such as cracks and pinholes, or with a uniform thickness. In addition, it is possible to reduce damage to the workpiece when forming the protective film.

[0275] For example, by forming a protective film using the ALD method, it is possible to form a uniform protective film with few defects on surfaces with complex uneven shapes, as well as on the top, side, and back surfaces of a touch panel.

[0276] In the above manner, a light-emitting device manufactured using the light-emitting device described in Embodiment 1 can be obtained.

[0277] The light-emitting device in this embodiment can have favorable characteristics because it uses the light-emitting device described in Embodiment 1. Specifically, the light-emitting device described in Embodiment 1 has favorable luminous efficiency, and therefore can have low power consumption.

[0278] 3A and 3B show an example of a light-emitting device in which a white-emitting light-emitting device is formed and a full color display is achieved by providing a colored layer (color filter), etc. Fig. 3A shows a substrate 1001, a base insulating film 1002, a gate insulating film 1003, gate electrodes 1006, 1007, and 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, anodes 1024W, 1024R, 1024G, and 1024B of the light-emitting device, a partition wall 1025, an EL layer 1028, a cathode 1029 of the light-emitting device, a sealing substrate 1031, a sealant 1032, etc.

[0279] 3A, the colored layers (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B) are provided on a transparent base material 1033. A black matrix 1035 may also be provided. The transparent base material 1033 on which the colored layers and black matrix are provided is aligned and fixed to the substrate 1001. The colored layers and black matrix 1035 are covered with an overcoat layer 1036. Also, in FIG. 3A, there are light-emitting layers from which light does not pass through the colored layers and exits to the outside, and light-emitting layers from which light passes through the colored layers of each color and exits to the outside. Light that does not pass through the colored layers is white, and light that passes through the colored layers is red, green, and blue, so that an image can be displayed using four color pixels.

[0280] 3B shows an example in which colored layers (a red colored layer 1034R, a green colored layer 1034G, and a blue colored layer 1034B) are formed between the gate insulating film 1003 and the first interlayer insulating film 1020. In this way, the colored layers may be provided between the substrate 1001 and the sealing substrate 1031.

[0281] Furthermore, the light-emitting device described above has a structure in which light is extracted from the substrate 1001 side on which the FET is formed (bottom emission type), but it may also have a structure in which light is extracted from the sealing substrate 1031 side (top emission type). A cross-sectional view of a top emission type light-emitting device is shown in FIG. 4. In this case, a light-opaque substrate can be used as the substrate 1001. The process is the same as for a bottom emission type light-emitting device up to the formation of a connection electrode that connects the FET and the anode of the light-emitting device. Thereafter, a third interlayer insulating film 1037 is formed to cover the electrode 1022. This insulating film may also serve as a planarizing film. The third interlayer insulating film 1037 can be formed using the same material as the second interlayer insulating film, as well as other known materials.

[0282] Although the anodes 1024W, 1024R, 1024G, and 1024B of the light-emitting device are referred to as anodes in this example, they may be cathodes. Furthermore, in the case of a top-emission light-emitting device such as that shown in FIG. 4, it is preferable that the anodes be reflective electrodes. The EL layer 1028 has the same configuration as that described for the EL layer 103 in the first embodiment, and has an element structure that allows white light emission.

[0283] In the top-emission structure shown in FIG. 4, sealing can be performed using a sealing substrate 1031 provided with colored layers (a red colored layer 1034R, a green colored layer 1034G, and a blue colored layer 1034B). The sealing substrate 1031 may be provided with a black matrix 1035 positioned between pixels. The colored layers (the red colored layer 1034R, the green colored layer 1034G, and the blue colored layer 1034B) and the black matrix may be covered with an overcoat layer 1036. Note that a light-transmitting substrate is used as the sealing substrate 1031. In addition, although an example of full-color display using four colors, red, green, blue, and white, is shown here, the present invention is not particularly limited, and full-color display using four colors, red, yellow, green, and blue, or three colors, red, green, and blue, may also be performed.

[0284] A microcavity structure is suitable for use in top-emission light-emitting devices. A light-emitting device with a microcavity structure can be obtained by using a reflective electrode as the anode and a semi-transparent / semi-reflective electrode as the cathode. At least an EL layer is present between the reflective electrode and the semi-transparent / semi-reflective electrode, and at least an emissive layer that serves as the light-emitting region is present.

[0285] The reflectance of the reflective electrode to visible light is 40% to 100%, preferably 70% to 100%, and the resistivity is 1×10 -2 The semi-transmitting and semi-reflective electrode has a visible light reflectance of 20% to 80%, preferably 40% to 70%, and a resistivity of 1×10 -2 It is assumed that the film has a resistance of Ωcm or less.

[0286] The light emitted from the light-emitting layer included in the EL layer is reflected by the reflective electrode and the semi-transmissive and semi-reflective electrode, causing resonance.

[0287] In this light-emitting device, the optical distance between the reflective electrode and the semi-transparent / semi-reflective electrode can be changed by changing the thickness of the transparent conductive film, the composite material described above, the carrier transport material, etc. This makes it possible to intensify light with resonant wavelengths and attenuate light with non-resonant wavelengths between the reflective electrode and the semi-transparent / semi-reflective electrode.

[0288] Note that, since the light reflected by the reflective electrode and returned (first reflected light) significantly interferes with the light (first incident light) that directly enters the semi-transmissive-semi-reflective electrode from the light-emitting layer, 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 greater than or equal to 1, and λ is the wavelength of the emitted light to be amplified). By adjusting this optical distance, the phases of the first reflected light and the first incident light can be matched, thereby further amplifying the light emitted from the light-emitting layer.

[0289] In the above configuration, the EL layer may have a structure having multiple light-emitting layers or a structure having a single light-emitting layer. For example, it may be combined with the above-mentioned tandem light-emitting device configuration, in which multiple EL layers are provided in one light-emitting device with a charge-generating layer sandwiched therebetween, and one or more light-emitting layers are formed in each EL layer.

[0290] The microcavity structure makes it possible to increase the light emission intensity of specific wavelengths in the front direction, thereby reducing power consumption. In the case of a light-emitting device that displays images using four sub-pixels of red, yellow, green, and blue, not only is the yellow light emitted effective in improving brightness, but the microcavity structure that matches the wavelength of each color can be applied to all sub-pixels, resulting in a light-emitting device with good characteristics.

[0291] The light-emitting device in this embodiment can have favorable characteristics because it uses the light-emitting device described in Embodiment 1. Specifically, the light-emitting device described in Embodiment 1 has favorable luminous efficiency, and therefore can have low power consumption.

[0292] Up to this point, we have explained active matrix light-emitting devices. From here on, we will explain passive matrix light-emitting devices. FIGS. 5A and 5B show a passive matrix light-emitting device manufactured by applying the present invention. FIG. 5A is a perspective view of the light-emitting device, and FIG. 5B is a cross-sectional view of FIG. 5A taken along the dashed-dotted line XY. In FIG. 5, an EL layer 955 is provided between an electrode 952 and an electrode 956 on a substrate 951. The edge of the electrode 952 is covered with an insulating layer 953. A partition layer 954 is provided on the insulating layer 953. The sidewalls of the partition layer 954 are inclined such that the distance between one sidewall and the other sidewall narrows as the distance approaches the substrate surface. That is, the cross section of the partition layer 954 in the short side direction is trapezoidal, and the bottom side (the side facing the same direction as the surface of the insulating layer 953 and in contact with the insulating layer 953) is shorter than the top side (the side facing the same direction as the surface of the insulating layer 953 and not in contact with the insulating layer 953). By providing the partition layer 954 in this manner, defects in the light-emitting device due to static electricity or the like can be prevented. Furthermore, the light-emitting device described in Embodiment 1 is used in a passive matrix light-emitting device, and the light-emitting device can be highly reliable or consumes less power.

[0293] The light emitting device described above is capable of individually controlling a large number of minute light emitting devices arranged in a matrix, and is therefore suitable for use as a display device for displaying images.

[0294] This embodiment mode can be freely combined with other embodiment modes.

[0295] (Embodiment 3) In this embodiment, an example in which the light-emitting device described in Embodiment 1 is used as a lighting device will be described with reference to Fig. 6. Fig. 6B is a top view of the lighting device, and Fig. 6A is a cross-sectional view taken along line ef shown in Fig. 6B.

[0296] In the lighting device of this embodiment, an anode 401 is formed on a light-transmitting substrate 400, which serves as a support. The anode 401 corresponds to the anode 101 in Embodiment 1. When light is extracted from the anode 401 side, the anode 401 is formed from a light-transmitting material.

[0297] A pad 412 for supplying a voltage to the cathode 404 is formed on the substrate 400 .

[0298] An EL layer 403 is formed on the anode 401. The EL layer 403 corresponds to the configuration of the EL layer 103 in Embodiment 1, or a configuration in which the light-emitting units 511 and 512 and the charge generation layer 513 are combined. For details of these configurations, please refer to the relevant descriptions.

[0299] Cathode 404 is formed to cover EL layer 403. Cathode 404 corresponds to cathode 102 in Embodiment 1. When light is extracted from the anode 401 side, cathode 404 is formed of a material with high reflectivity. Cathode 404 is connected to pad 412 to supply voltage.

[0300] As described above, the lighting device described in this embodiment has a light-emitting device including the anode 401, the EL layer 403, and the cathode 404. Since the light-emitting device has high luminous efficiency, the lighting device in this embodiment can be a lighting device with low power consumption.

[0301] The lighting device is completed by bonding and sealing substrate 407, on which the light-emitting device having the above configuration is formed, to substrate 400 using sealants 405 and 406. Either sealant 405 or 406 can be used. Also, a desiccant can be mixed into inner sealant 406 (not shown in FIG. 6B), which can absorb moisture and improve reliability.

[0302] Furthermore, an external input terminal can be formed by extending a portion of the pad 412 and the anode 401 outside the sealing materials 405 and 406. An IC chip 420 equipped with a converter or the like may also be provided thereon.

[0303] As described above, the lighting device described in this embodiment uses the light-emitting device described in Embodiment 1 as its EL element, and can be a lighting device with low power consumption.

[0304] This embodiment mode can be freely combined with other embodiment modes.

[0305] (Fourth embodiment) In this embodiment, an example of an electronic device including the light-emitting device described in Embodiment 1 as a part thereof will be described. The light-emitting device described in Embodiment 1 has good light-emitting efficiency and low power consumption. As a result, the electronic device described in this embodiment can be an electronic device having a light-emitting portion with low power consumption.

[0306] Examples of electronic devices to which the light-emitting devices are applied include television sets (also called televisions or television receivers), computer monitors, digital cameras, digital video cameras, digital photo frames, mobile phones (also called mobile phones or mobile phone devices), portable game machines, personal digital assistants, sound players, large game machines such as pachinko machines, etc. Specific examples of these electronic devices are shown below.

[0307] 7A illustrates an example of a television set. The television set has a display portion 7103 incorporated in a housing 7101. Here, the housing 7101 is supported by a stand 7105. The display portion 7103 can display images, and the light-emitting devices described in Embodiment 1 are arranged in a matrix.

[0308] The television set can be operated using operation switches provided on the housing 7101 or a separate remote control 7110. Channels and volume can be controlled using operation keys 7109 provided on the remote control 7110, and images displayed on the display portion 7103 can be controlled. The remote control 7110 may be provided with a display portion 7107 that displays information output from the remote control 7110. Note that the light-emitting devices described in Embodiment 1 arranged in a matrix can also be applied to the display portion 7107.

[0309] The television device is configured to include a receiver, a modem, etc. The receiver can receive general television broadcasts, and by connecting to a wired or wireless communication network via the modem, it is also possible to perform one-way (from sender to receiver) or two-way (between sender and receiver, or between receivers, etc.) information communication.

[0310] FIG. 7B1 shows a computer including a main body 7201, a housing 7202, a display portion 7203, a keyboard 7204, an external connection port 7205, a pointing device 7206, and the like. This computer is manufactured by using the light-emitting devices described in Embodiment 1 arranged in a matrix for the display portion 7203. The computer in FIG. 7B1 may have a configuration as shown in FIG. 7B2. The computer in FIG. 7B2 is provided with a display portion 7210 instead of the keyboard 7204 and the pointing device 7206. The display portion 7210 is a touch panel type, and input can be performed by operating an input display displayed on the display portion 7210 with a finger or a dedicated pen. The display portion 7210 can display not only an input display but also other images. The display portion 7203 may also be a touch panel. The two screens are connected by a hinge, which can prevent the screens from being scratched or broken during storage or transportation.

[0311] 7C shows an example of a mobile terminal. The mobile phone includes a display portion 7402 built into a housing 7401, operation buttons 7403, an external connection port 7404, a speaker 7405, a microphone 7406, and the like. Note that the mobile phone has the display portion 7402 in which the light-emitting devices described in Embodiment 1 are arranged in a matrix.

[0312] 7C can be configured so that information can be input by touching the display portion 7402 with a finger or the like. In this case, operations such as making a call or creating an e-mail can be performed by touching the display portion 7402 with a finger or the like.

[0313] The screen of the display unit 7402 has three main modes. The first is a display mode that mainly displays images, the second is an input mode that mainly inputs information such as characters, and the third is a display+input mode that combines the display mode and the input mode.

[0314] For example, when making a call or creating an e-mail, the display portion 7402 may be set to a character input mode mainly for inputting characters, and characters displayed on the screen may be input. In this case, it is preferable to display a keyboard or number buttons on most of the screen of the display portion 7402.

[0315] Furthermore, by providing a detection device having a sensor for detecting tilt, such as a gyroscope or an acceleration sensor, inside the mobile terminal, the orientation of the mobile terminal (portrait or landscape) can be determined and the screen display of the display portion 7402 can be automatically switched.

[0316] The screen mode can be switched by touching the display portion 7402 or by operating the operation buttons 7403 on the housing 7401. The screen mode can also be switched depending on the type of image displayed on the display portion 7402. For example, if the image signal to be displayed on the display portion is moving image data, the display mode is selected, and if it is text data, the input mode is selected.

[0317] In addition, in the input mode, a signal detected by an optical sensor of the display portion 7402 may be detected, and if there is no input by touch operation on the display portion 7402 for a certain period of time, the screen mode may be controlled to switch from the input mode to the display mode.

[0318] The display portion 7402 can also function as an image sensor. For example, personal authentication can be performed by touching the display portion 7402 with a palm or a finger to capture an image of a palm print, fingerprint, or the like. Furthermore, by using a backlight that emits near-infrared light or a sensing light source that emits near-infrared light for the display portion, finger veins, palm veins, or the like can also be captured.

[0319] Note that the structure described in this embodiment mode can be used by combining the structures described in any of Embodiment Modes 1 to 3 as appropriate.

[0320] As described above, the light-emitting device having the light-emitting device described in Embodiment 1 has a very wide range of application, and this light-emitting device can be applied to electronic devices in a variety of fields. By using the light-emitting device described in Embodiment 1, electronic devices with low power consumption can be obtained.

[0321] FIG. 8A is a schematic diagram showing an example of a cleaning robot.

[0322] The cleaning robot 5100 has a display 5101 arranged on its top surface, multiple cameras 5102 arranged on its side, a brush 5103, and an operation button 5104. Although not shown, the cleaning robot 5100 is also provided with tires, a suction port, and the like on its bottom surface. The cleaning robot 5100 also has various other sensors such as an infrared sensor, an ultrasonic sensor, an acceleration sensor, a piezoelectric sensor, an optical sensor, and a gyro sensor. The cleaning robot 5100 also has wireless communication means.

[0323] The cleaning robot 5100 can move by itself, detect dust 5120, and suck up the dust from a suction port provided on the bottom surface.

[0324] Furthermore, the cleaning robot 5100 can analyze the image captured by the camera 5102 to determine whether there are any obstacles such as walls, furniture, or steps. Furthermore, if the image analysis detects an object that may become tangled in the brush 5103, such as a wire, the rotation of the brush 5103 can be stopped.

[0325] The display 5101 can display the remaining battery level, the amount of dust that has been sucked up, etc. The path traveled by the cleaning robot 5100 may be displayed on the display 5101. The display 5101 may also be a touch panel, and an operation button 5104 may be provided on the display 5101.

[0326] The cleaning robot 5100 can communicate with a portable electronic device 5140 such as a smartphone. Images captured by the camera 5102 can be displayed on the portable electronic device 5140. Therefore, the owner of the cleaning robot 5100 can know the state of the room even when he or she is away from home. In addition, the display on the display 5101 can be confirmed on the portable electronic device such as a smartphone.

[0327] The light-emitting device according to one embodiment of the present invention can be used for the display 5101 .

[0328] The robot 2100 shown in FIG. 8B includes a computing device 2110, an illumination sensor 2101, a microphone 2102, an upper camera 2103, a speaker 2104, a display 2105, a lower camera 2106, an obstacle sensor 2107, and a movement mechanism 2108.

[0329] The microphone 2102 has a function of detecting the user's speaking voice, environmental sounds, etc. The speaker 2104 has a function of emitting sound. The robot 2100 can communicate with the user using the microphone 2102 and the speaker 2104.

[0330] The display 2105 has a function of displaying various information. The robot 2100 can display information desired by the user on the display 2105. The display 2105 may be equipped with a touch panel. The display 2105 may also be a detachable information terminal, which can be installed in a fixed position on the robot 2100 to enable charging and data transfer.

[0331] The upper camera 2103 and the lower camera 2106 have a function of capturing images of the surroundings of the robot 2100. In addition, the obstacle sensor 2107 can detect the presence or absence of an obstacle in the moving 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 of one embodiment of the present invention can be used for the display 2105.

[0332] 8C 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 for measuring force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared light), a microphone 5008, a display unit 5002, a support unit 5012, and earphones 5013.

[0333] The light-emitting device of one embodiment of the present invention can be used for the display portion 5001 and the display portion 5002 .

[0334] 9 shows an example in which the light-emitting device described in Embodiment 1 is used in a desk lamp, which is a lighting device. The desk lamp shown in FIG. 9 includes a housing 2001 and a light source 2002, and the lighting device described in Embodiment 3 may be used as the light source 2002.

[0335] FIG. 10 shows an example in which the light-emitting device described in Embodiment 1 is used as an indoor lighting device 3001. The light-emitting device described in Embodiment 1 has high emission efficiency and can therefore be used as a lighting device with low power consumption. In addition, the light-emitting device described in Embodiment 1 can be made large in area and can therefore be used as a large-area lighting device. In addition, the light-emitting device described in Embodiment 1 is thin and can therefore be used as a thin lighting device.

[0336] The light-emitting device described in Embodiment 1 can also be mounted on a windshield or dashboard of an automobile. Figure 11 shows one mode in which the light-emitting device described in Embodiment 1 is used on a windshield or dashboard of an automobile. Display regions 5200 to 5203 are displays provided using the light-emitting device described in Embodiment 1.

[0337] The display region 5200 and the display region 5201 are display devices equipped with the light-emitting device described in Embodiment 1 and provided on the windshield of an automobile. The light-emitting device described in Embodiment 1 can be a so-called see-through display device, in which the opposite side can be seen through, by fabricating the anode and cathode using light-transmitting electrodes. A see-through display can be installed on the windshield of an automobile without obstructing the view. Note that when a transistor or the like is provided for driving the device, a light-transmitting transistor such as an organic transistor made of an organic semiconductor material or a transistor using an oxide semiconductor is preferably used.

[0338] The display area 5202 is a display device provided on a pillar and incorporating the light-emitting device described in Embodiment 1. By displaying an image from an imaging means provided on the vehicle body in the display area 5202, the view blocked by the pillar can be complemented. Similarly, the display area 5203 provided on the dashboard can complement the view blocked by the vehicle body by displaying an image from an imaging means provided on the outside of the vehicle, thereby compensating for blind spots and improving safety. By displaying an image to complement the invisible parts, safety can be confirmed more naturally and without discomfort.

[0339] The display area 5203 can also provide various other information such as navigation information, a speedometer, a tachometer, and air conditioning settings. The display items and layout can be changed as needed to suit the user's preferences. This information can also be provided in the display areas 5200 to 5202. The display areas 5200 to 5203 can also be used as lighting devices.

[0340] 12A and 12B show a foldable mobile information terminal 5150. The foldable mobile information terminal 5150 has a housing 5151, a display area 5152, and a bending portion 5153. FIG. 12A shows the mobile information terminal 5150 in an unfolded state. FIG. 12B shows the mobile information terminal in a folded state. Although the mobile information terminal 5150 has a large display area 5152, it is compact and highly portable when folded.

[0341] The display area 5152 can be folded in half by the bending portion 5153. The bending portion 5153 is composed of an expandable member and multiple support members, and when folding, the expandable member is stretched. The bending portion 5153 is folded with a curvature radius of 2 mm or more, preferably 3 mm or more.

[0342] Note that the display region 5152 may be a touch panel (input / output device) equipped with a touch sensor (input device). The light-emitting device of one embodiment of the present invention can be used for the display region 5152.

[0343] 13A to 13C show a foldable mobile information terminal 9310. Fig. 13A shows the mobile information terminal 9310 in an unfolded state. Fig. 13B shows the mobile information terminal 9310 in a state in the process of changing from one of the unfolded state and the folded state to the other. Fig. 13C shows the mobile information terminal 9310 in a folded state. The mobile information terminal 9310 has excellent portability in a folded state, and has excellent display visibility due to a seamless, wide display area in an unfolded state.

[0344] The display panel 9311 is supported by three housings 9315 connected by hinges 9313. Note that the display panel 9311 may be a touch panel (input / output device) equipped with a touch sensor (input device). The display panel 9311 can be reversibly transformed from an unfolded state of the mobile information terminal 9310 to a folded state by bending the two housings 9315 via the hinges 9313. The light-emitting device of one embodiment of the present invention can be used for the display panel 9311. [Example]

[0345] In this example, a light-emitting device 1 and a light-emitting device 2 according to one embodiment of the present invention, which are described in the embodiment, and comparative light-emitting devices 1 to 3 will be described. The structural formulae of organic compounds used in this example are shown below.

[0346] [ka]

[0347] (Method for fabricating light-emitting device 1) First, a transparent electrode made of indium tin oxide containing silicon oxide (ITSO) was formed on a glass substrate by sputtering to a thickness of 55 nm to form an anode 101. The electrode area was 4 mm 2 (2mm x 2mm).

[0348] 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.

[0349] Then, 10 -4 The substrate was introduced into a vacuum deposition apparatus whose internal pressure had been reduced to about Pa, and after vacuum baking at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, the substrate was allowed to cool for about 30 minutes.

[0350] Next, the substrate on which the anode 101 was formed was fixed to a substrate holder installed in a vacuum deposition apparatus so that the surface on which the anode 101 was formed faced downward. N-(1,1'-biphenyl-2-yl)-N-(3,3'',5',5''-tetra-t-butyl-1,1':3',1''-terphenyl-5-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPoFBi-02) represented by the above structural formula (i) and an electron acceptor material (OCHD-001) were co-deposited on the anode 101 by a deposition method to a thickness of 10 nm in a weight ratio of 1:0.1 (=mmtBumTPoFBi-02:OCHD-001) to form a hole injection layer 111.

[0351] On the hole injection layer 111, mmtBumTPoFBi-02 was evaporated to a thickness of 140 nm to form a hole transport layer 112.

[0352] Next, N-[4-(9H-carbazol-9-yl)phenyl]-N-[4-(4-dibenzofuranyl)phenyl]-[1,1':4',1''-terphenyl]-4-amine (abbreviation: YGTPDBfB) represented by the above structural formula (ii) was vapor-deposited on the hole transport layer 112 to a thickness of 10 nm to form an electron blocking layer.

[0353] Thereafter, 2-(10-phenyl-9-anthracenyl)-benzo[b]naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA) represented by the above structural formula (iii) and 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) represented by the above structural formula (iv) were co-deposited to a thickness of 25 nm in a weight ratio of 1:0.015 (=Bnf(II)PhA:3,10PCA2Nbf(IV)-02) to form the light-emitting layer 113.

[0354] Thereafter, 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)-1,1'-biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn) represented by the above structural formula (v) was deposited to a thickness of 10 nm to form a hole blocking layer, and 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn) represented by the above structural formula (xviii) and 8-quinolinolato-lithium (abbreviation: Liq) represented by the above structural formula (vi) were co-deposited to a thickness of 20 nm in a weight ratio of 1:1 (=mPn-mDMePyPTzn:Liq) to form an electron transport layer 114.

[0355] After forming the electron transport layer 114, Liq was deposited to a thickness of 1 nm to form the electron injection layer 115, and finally, aluminum was evaporated to a thickness of 200 nm to form the cathode 102, thereby producing the light-emitting device 1.

[0356] (Method for fabricating light-emitting device 2) Light-emitting device 2 was fabricated in the same manner as light-emitting device 1, except that YGTPDBfB in the electron blocking layer of light-emitting device 1 was replaced with 4-(dibenzothiophen-4-yl)-4'-phenyl-4''-(9-phenyl-9H-carbazol-2-yl)triphenylamine (abbreviation: PCBBiPDBt-02) represented by the above structural formula (vii).

[0357] (Method for producing comparative light-emitting device 1) Comparative light-emitting device 1 was fabricated in the same manner as light-emitting device 1, except that YGTPDBfB in the electron blocking layer of light-emitting device 1 was replaced with N-(1,1'-biphenyl-2-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi(9H-fluorene)-4-amine (abbreviation: oFBiSF), represented by the above structural formula (viii).

[0358] (Method for producing comparative light-emitting device 2) Comparative light-emitting device 2 was fabricated in the same manner as light-emitting device 1, except that YGTPDBfB in the electron blocking layer of light-emitting device 1 was replaced with N-[1,1'-biphenyl]-4-yl-N-(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi[9H-fluorene]-4-amine (abbreviation: FBiSF(4)), which is represented by the above structural formula (ix).

[0359] (How to create comparative light-emitting device 3) Comparative light-emitting device 3 was fabricated in the same manner as light-emitting device 1, except that YGTPDBfB in the electron blocking layer of light-emitting device 1 was replaced with N-(1,1'-biphenyl-4-yl)-N-(1,1'-biphenyl-2-yl)-9,9'-spirobi(9H-fluorene)-2-amine (abbreviation: oBBASF), represented by the above structural formula (x).

[0360] The device structures of light-emitting device 1, light-emitting device 2, and comparative light-emitting devices 1 to 3 are summarized in the table below.

[0361] [Table 1]

[0362] Note that mmtBumTPoFBi-02 is a low-refractive-index hole-transport material whose ordinary refractive index is 1.69 to 1.70, ranging from 1.50 to 1.75, throughout the entire blue emission region (455 nm to 465 nm). Its ordinary refractive index at 633 nm is 1.64, ranging from 1.45 to 1.70. Bnf(II)PhA has an ordinary refractive index of 1.89 to 1.91 throughout the entire blue emission region (455 nm to 465 nm), and its ordinary refractive index at 633 nm is 1.79. Because the concentration of 3,10PCA2Nbf(IV)-02 in the light-emitting layer 113 is low, the refractive index of the light-emitting layer 113 is equivalent to that of Bnf(II)PhA. Therefore, the light-emitting device of one embodiment of the present invention is a light-emitting device in which the refractive index of the hole-transport layer 112 is lower than that of the light-emitting layer 113.

[0363] Furthermore, YGTPDBfB and PCBBiPDBt-02 used in the electron blocking layers of Light-Emitting Device 1 and Light-Emitting Device 2 are monoamine compounds having a triarylamine structure that has a group containing a carbazole structure, a group containing a dibenzofuran structure or a dibenzothiophene structure, and a group containing an aromatic hydrocarbon structure having 6 to 18 carbon atoms. Note that the three materials used in the electron blocking layers of Comparative Light-Emitting Devices 1 to 3 are organic compounds that do not have the above structure.

[0364] The above light-emitting device and the comparative light-emitting device were sealed with a glass substrate in a nitrogen atmosphere glove box to prevent the light-emitting device from being exposed to the atmosphere (a UV-curable sealant was applied around the element, UV was irradiated only on the sealant without irradiating the light-emitting device, and heat-treated at 80°C under atmospheric pressure for 1 hour), and then the initial characteristics of these light-emitting devices were measured.

[0365] The luminance-current density characteristics of light-emitting device 1, light-emitting device 2, and comparative light-emitting devices 1 to 3 are shown in Fig. 14, their luminance-voltage characteristics in Fig. 15, their current efficiency-luminance characteristics in Fig. 16, their current-voltage characteristics in Fig. 17, their external quantum efficiency-luminance characteristics in Fig. 18, their power efficiency-luminance characteristics in Fig. 19, and their emission spectra in Fig. 20. Furthermore, the 1000 cd / m 2 The main characteristics in this range are shown in Table 2. The luminance, CIE chromaticity, and emission spectrum were measured using a spectroradiometer (SR-UL1R, manufactured by Topcon Corporation) at room temperature.

[0366] [Table 2]

[0367] 14 to 20 and Table 2 show that the light-emitting device 1, the light-emitting device 2, and the comparative light-emitting device 1 according to one embodiment of the present invention are light-emitting devices with good external quantum efficiency. In particular, the light-emitting device 2 had a low driving voltage and, as a result, was a light-emitting device with very good power efficiency.

[0368] In addition, the current density is 50mA / cm 2 A graph showing the change in luminance with respect to the driving time in the case of the light-emitting device 1 is shown in Fig. 21. As shown in Fig. 21, it was found that both the light-emitting device 1 and the light-emitting device 2 have a long life. On the other hand, it was found that the comparative light-emitting devices 1 to 3 deteriorated more quickly than the light-emitting devices 1 and 2.

[0369] In this way, a light-emitting device having a layer containing a monoamine compound having a specific structure formed in contact with a low refractive index layer can be a light-emitting device with good characteristics. Specifically, it can be a light-emitting device with a long life, good luminous efficiency, or a light-emitting device with a low driving voltage. [Example]

[0370] This example shows the results of investigating the ease of carrier (hole, in this case) flow in the stacked layer structure formed between the anode and the light-emitting layer of the light-emitting device according to one embodiment of the present invention described in the embodiment. Measurements were performed using a measurement device (hole-only element) through which only holes flow. Device 3 and Device 4 are measurement devices that have a part of the stacked layer structure according to one embodiment of the present invention, and Comparative Devices 4 to 7 are measurement devices that do not have a part of the stacked layer structure according to one embodiment of the present invention.

[0371] The structural formulae of the organic compounds used in Device 3, Device 4 and Comparative Devices 4 to 7 are shown below.

[0372] [ka]

[0373] (Method for fabricating Device 3) First, a 100 nm thick silver-palladium-copper alloy (APC) film was formed on a glass substrate, and then a 45 nm thick indium tin oxide (ITSO) film containing silicon oxide was formed by sputtering to form an anode. The electrode area was 4 mm 2 (2mm x 2mm).

[0374] 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.

[0375] Then, 10 -4 The substrate was introduced into a vacuum deposition apparatus whose internal pressure had been reduced to about Pa, and after vacuum baking at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, the substrate was allowed to cool for about 30 minutes.

[0376] Next, the substrate on which the anode 101 was formed was fixed to a substrate holder installed in a vacuum deposition apparatus so that the surface on which the anode 101 was formed faced downward, and N-[(3',5'-ditertiarybutyl)-1,1'-biphenyl-4-yl]-N-(4-cyclohexylphenyl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBuBichPAF) represented by the above structural formula (xi) and an electron acceptor material (OCHD-001) were co-deposited onto the anode 101 by a deposition method to a thickness of 10 nm in a weight ratio of 1:0.1 (= mmtBuBichPAF:OCHD-001).

[0377] Subsequently, mmtBuBichPAF was evaporated to a thickness of 50 nm, and 4-(dibenzothiophen-4-yl)-4'-phenyl-4''-(9-phenyl-9H-carbazol-2-yl)triphenylamine (abbreviation: PCBBiPDBt-02) represented by (vii) was evaporated to a thickness of 50 nm.

[0378] Thereafter, PCBBiPDBt-02 and OCHD-001 were co-deposited to a thickness of 10 nm at a weight ratio of 1:0.1 (= PCBBiPDBt-02:OCHD-001).

[0379] Finally, aluminum was evaporated to a thickness of 100 nm to prepare Device 3, which was used for measurement.

[0380] (Method for fabricating Device 4) Device 4 was fabricated in the same manner as Device 3, except that mmtBuBichPAF in Device 3 was replaced with N-(1,1'-biphenyl-2-yl)-N-(3,3'',5',5''-tetra-t-butyl-1,1':3',1''-terphenyl-5-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPoFBi-02) represented by the above structural formula (i).

[0381] (Method for fabricating comparative device 4) Comparative device 4 was fabricated in the same manner as device 3, except that mmtBuBichPAF in device 3 was replaced with N-(1,1'-biphenyl-4-yl)-9,9-dimethyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9H-fluoren-2-amine (abbreviation: PCBBiF) represented by the above structural formula (xii).

[0382] (Method for fabricating comparative device 5) Comparative device 5 was prepared in the same manner as comparative device 4, except that PCBBiPDBt-02 in comparative device 4 was replaced with N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP) represented by the above structural formula (xiii).

[0383] (Method for producing comparative device 6) Comparative Device 6 was fabricated in the same manner as Device 3, except that PCBBiPDBt-02 in Device 3 was replaced with DBfBB1TP.

[0384] (Method for producing comparative device 7) Comparative Device 7 was fabricated in the same manner as Device 4, except that PCBBiPDBt-02 in Device 4 was replaced with DBfBB1TP.

[0385] The device structures of Device 3, Device 4, and Comparative Devices 4 to 7 are summarized in the table below.

[0386] [Table 3]

[0387] Of the organic compounds used in the device, mmtBuBichPAF has an ordinary refractive index of 1.72 or more and 1.73 or less, and 1.50 or more and 1.75 or less, throughout the entire blue light-emitting region (455 nm or more and 465 nm or less), and its ordinary refractive index at 633 nm is 1.65, and its ordinary refractive index is in the range of 1.45 or more and 1.70 or less, making it an organic compound with low refractive index and hole-transport properties. mmtBumTPoFBi-02 has an ordinary refractive index of 1.69 or more and 1.70 or less, and 1.50 or more and 1.75 or less, throughout the entire blue light-emitting region (455 nm or more and 465 nm or less), and its ordinary refractive index at 633 nm is 1.64, and its ordinary refractive index is in the range of 1.45 or more and 1.70 or less, making it an organic compound with low refractive index and hole-transport properties.

[0388] Among the organic compounds used in the device, PCBBiPDBt-02 is a monoamine compound having a triarylamine structure with a group containing a carbazole structure, a group containing a dibenzofuran structure or a dibenzothiophene structure, and a group containing an aromatic hydrocarbon structure having 6 to 18 carbon atoms. DBfBB1TP does not contain a carbazole structure and is therefore an organic compound that does not have the above structure.

[0389] The above light-emitting device and the comparative light-emitting device were sealed with a glass substrate in a nitrogen atmosphere glove box to prevent the light-emitting device from being exposed to the atmosphere (a UV-curable sealant was applied around the element, UV was irradiated only on the sealant without irradiating the light-emitting device, and heat-treated at 80°C under atmospheric pressure for 1 hour), and then the initial characteristics of these light-emitting devices were measured.

[0390] These devices mimic the stacked structure between the anode and the light-emitting layer in a light-emitting device, allowing only holes to flow. By measuring such devices, we can observe the hole injection and transport properties without being affected by electron injection and transport or recombination in the light-emitting layer.

[0391] The current density-voltage characteristics of Device 3, Device 4, and Comparative Device 4 to Comparative Device 4 are shown in FIG.

[0392] Figure 22 shows that the performance of Comparative Devices 6 and 7, which use the low-refractive-index materials mmtBuBichPAF and mmtBumTPoFBi-02, is inferior to that of Comparative Device 5, which does not. This indicates that the hole injection and transport properties of mmtBuBichPAF and mmtBumTPoFBi-02 are inferior to those of PCBBiF. However, Devices 3 and 4, which were fabricated by contacting PCBBiPDBt-02 with mmtBuBichPAF and mmtBumTPoFBi-02, exhibited performance equivalent to that of Comparative Device 4, which did not use a low-refractive-index material. Thus, we found that the current density-voltage characteristics were dramatically improved by contacting a monoamine compound, such as PCBBiPDBt-02, with a triarylamine structure having a carbazole group, a dibenzofuran or dibenzothiophene group, and a group containing an aromatic hydrocarbon structure with 6 to 18 carbon atoms. [Example]

[0393] In this example, light-emitting device 5, light-emitting device 6, and comparative light-emitting devices 8 to 11 according to one embodiment of the present invention will be described. The structural formulae of organic compounds used in this example are shown below.

[0394] [ka]

[0395] (Method for fabricating light-emitting device 5) First, a transparent electrode made of indium tin oxide containing silicon oxide (ITSO) was formed on a glass substrate by sputtering to a thickness of 55 nm to form an anode 101. The electrode area was 4 mm 2 (2mm x 2mm).

[0396] 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.

[0397] Then, 10 -4 The substrate was introduced into a vacuum deposition apparatus whose internal pressure had been reduced to about Pa, and after vacuum baking at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, the substrate was allowed to cool for about 30 minutes.

[0398] Next, the substrate on which the anode 101 was formed was fixed to a substrate holder installed in a vacuum deposition apparatus so that the surface on which the anode 101 was formed faced downward. N-(1,1'-biphenyl-2-yl)-N-(3,3'',5',5''-tetra-t-butyl-1,1':3',1''-terphenyl-5-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPoFBi-02) represented by the above structural formula (i) and an electron acceptor material (OCHD-001) were co-deposited on the anode 101 by a deposition method to a thickness of 10 nm in a weight ratio of 1:0.1 (=mmtBumTPoFBi-02:OCHD-001) to form a hole injection layer 111.

[0399] On the hole injection layer 111, mmtBumTPoFBi-02 was evaporated to a thickness of 100 nm to form a hole transport layer 112.

[0400] Next, 4-(dibenzothiophen-4-yl)-4'-phenyl-4''-(9-phenyl-9H-carbazol-2-yl)triphenylamine (abbreviation: PCBBiPDBt-02) represented by the above structural formula (vii) was vapor-deposited on the hole transport layer 112 to a thickness of 10 nm to form an electron blocking layer.

[0401] Thereafter, 2-(10-phenyl-9-anthracenyl)-benzo[b]naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA) represented by the above structural formula (iii) and 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) represented by the above structural formula (iv) were co-deposited to a thickness of 25 nm in a weight ratio of 1:0.015 (=Bnf(II)PhA:3,10PCA2Nbf(IV)-02) to form the light-emitting layer 113.

[0402] Thereafter, 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)-1,1'-biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn) represented by the above structural formula (v) was deposited to a thickness of 10 nm to form a hole blocking layer, and 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn) represented by the above structural formula (xviii) and 8-quinolinolato-lithium (abbreviation: Liq) represented by the above structural formula (vi) were co-deposited to a thickness of 15 nm in a weight ratio of 1:1 (=mPn-mDMePyPTzn:Liq) to form an electron transport layer 114.

[0403] After forming the electron transport layer 114, Liq was deposited to a thickness of 1 nm to form the electron injection layer 115, and finally, aluminum was evaporated to a thickness of 200 nm to form the cathode 102, thereby producing the light-emitting device 5.

[0404] (Method for fabricating light-emitting device 6) Light-emitting device 6 was fabricated in the same manner as light-emitting device 5, except that PCBBiPDBt-02 in the electron blocking layer of light-emitting device 5 was replaced with 4-[3-(dibenzothiophen-4-yl)phenyl]-4'-phenyl-4''-(9-phenyl-9H-carbazol-2-yl)triphenylamine (abbreviation: pmPCBBiBPDBt-02) represented by the above structural formula (vii).

[0405] (Method for producing comparative light-emitting device 8) Comparative light-emitting device 8 was fabricated in the same manner as light-emitting device 5, except that PCBBiPDBt-02 in the electron blocking layer of light-emitting device 5 was replaced with N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP) represented by the above structural formula (xiii).

[0406] (Method for producing comparative light-emitting device 9) Comparative light-emitting device 9 was fabricated in the same manner as light-emitting device 5, except that mmtBumTPoFBi-02 in the hole injection layer and hole transport layer of light-emitting device 5 was replaced with N-(1,1'-biphenyl-4-yl)-9,9-dimethyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9H-fluoren-2-amine (abbreviation: PCBBiF) represented by the above structural formula (xii).

[0407] (Method for producing comparative light-emitting device 10) Comparative light-emitting device 10 was fabricated in the same manner as light-emitting device 6, except that mmtBumTPoFBi-02 in the hole-injection layer and hole-transport layer of light-emitting device 6 was replaced with PCBBiF.

[0408] (Method for producing comparative light-emitting device 11) Comparative light-emitting device 11 was fabricated in the same manner as light-emitting device 6, except that mmtBumTPoFBi-02 in the hole-injection layer and hole-transport layer of comparative light-emitting device 8 was replaced with PCBBiF.

[0409] The device structures of light-emitting device 5, light-emitting device 6, and comparative light-emitting devices 8 to 11 are summarized in the table below.

[0410] [Table 4]

[0411] [Table 5]

[0412] Note that mmtBumTPoFBi-02 is a low-refractive-index hole-transport material whose ordinary refractive index is 1.69 to 1.70, ranging from 1.50 to 1.75, throughout the entire blue emission region (455 nm to 465 nm). Its ordinary refractive index at 633 nm is 1.64, ranging from 1.45 to 1.70. Bnf(II)PhA has an ordinary refractive index of 1.89 to 1.91 throughout the entire blue emission region (455 nm to 465 nm), and its ordinary refractive index at 633 nm is 1.79. Because the concentration of 3,10PCA2Nbf(IV)-02 in the light-emitting layer 113 is low, the refractive index of the light-emitting layer 113 is equivalent to that of Bnf(II)PhA. Therefore, the light-emitting device of one embodiment of the present invention is a light-emitting device in which the refractive index of the hole-transport layer 112 is lower than that of the light-emitting layer 113.

[0413] Furthermore, PCBBiPDBt-02 and pmPCBBiBPDBt-02 used in the electron blocking layers of light-emitting device 5 and light-emitting device 6 are monoamine compounds having a triarylamine structure that has a group containing a carbazole structure, a group containing a dibenzofuran structure or a dibenzothiophene structure, and a group containing an aromatic hydrocarbon structure having 6 to 18 carbon atoms.

[0414] The above light-emitting device and the comparative light-emitting device were sealed with a glass substrate in a nitrogen atmosphere glove box to prevent the light-emitting device from being exposed to the atmosphere (a UV-curable sealant was applied around the element, UV was irradiated only on the sealant without irradiating the light-emitting device, and heat-treated at 80°C under atmospheric pressure for 1 hour), and then the initial characteristics of these light-emitting devices were measured.

[0415] The luminance-current density characteristics of light-emitting device 5, light-emitting device 6, and comparative light-emitting devices 8 to 11 are shown in Figure 23, their luminance-voltage characteristics in Figure 24, their current efficiency-luminance characteristics in Figure 25, their current-voltage characteristics in Figure 26, their external quantum efficiency-luminance characteristics in Figure 27, their power efficiency-luminance characteristics in Figure 28, and their emission spectra in Figure 29. The 1000 cd / m 2 The main characteristics in this range are shown in Table 6. The luminance, CIE chromaticity, and emission spectrum were measured using a spectroradiometer (SR-UL1R, manufactured by Topcon Corporation) at room temperature.

[0416] [Table 6]

[0417] 23 to 29 and Table 6, it can be seen that light-emitting devices 5 and 6 of one embodiment of the present invention have good external quantum efficiency and a suppressed decrease in driving voltage due to the provision of PCBBiPDBt-02 and pmPCBBiBPDBt-02 in contact with the low-refractive-index material mmtBumTPoFBi-02, and therefore are light-emitting elements with good power efficiency. Note that pmPCBBiBPDBt-02, in which a dibenzothiophenyl group is bonded to the nitrogen of an amine via a meta-substituted phenylene group, is preferred because it has a greater effect of improving efficiency.

[0418] In this way, a light-emitting device having a layer containing a monoamine compound having a specific structure formed in contact with a low refractive index layer can be a light-emitting device with good characteristics. Specifically, it can be a light-emitting device with a long life, good luminous efficiency, or a light-emitting device with a low driving voltage. [Example]

[0419] Example 7 In this example, the light-emitting device 7 according to one embodiment of the present invention described in the embodiment will be described. The structural formulas of organic compounds used in this example are shown below.

[0420] [ka]

[0421] (Method for fabricating light-emitting device 7) First, a transparent electrode made of indium tin oxide containing silicon oxide (ITSO) was formed on a glass substrate by sputtering to a thickness of 55 nm to form an anode 101. The electrode area was 4 mm 2 (2mm x 2mm).

[0422] 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.

[0423] Then, 10 -4 The substrate was introduced into a vacuum deposition apparatus whose internal pressure had been reduced to about Pa, and after vacuum baking at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, the substrate was allowed to cool for about 30 minutes.

[0424] Next, the substrate on which the anode 101 was formed was fixed to a substrate holder installed in a vacuum deposition apparatus so that the surface on which the anode 101 was formed faced downward. N-(1,1'-biphenyl-2-yl)-N-(3,3'',5',5''-tetra-t-butyl-1,1':3',1''-terphenyl-5-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBumTPoFBi-02) represented by the above structural formula (i) and an electron acceptor material (OCHD-001) were co-deposited on the anode 101 by a deposition method to a thickness of 10 nm in a weight ratio of 1:0.1 (=mmtBumTPoFBi-02:OCHD-001) to form a hole injection layer 111.

[0425] On the hole injection layer 111, mmtBumTPoFBi-02 was evaporated to a thickness of 100 nm to form a hole transport layer 112.

[0426] Next, 4-[3-(dibenzothiophen-4-yl)phenyl]-4'-phenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: pmPCBBiBPDBt) represented by the above structural formula (xv) was vapor-deposited on the hole transport layer 112 to a thickness of 10 nm to form an electron blocking layer.

[0427] Thereafter, 2-(10-phenyl-9-anthracenyl)-benzo[b]naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA) represented by the above structural formula (iii) and 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) represented by the above structural formula (iv) were co-deposited to a thickness of 25 nm in a weight ratio of 1:0.015 (=Bnf(II)PhA:3,10PCA2Nbf(IV)-02) to form the light-emitting layer 113.

[0428] Thereafter, 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)-1,1'-biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn) represented by the above structural formula (v) was deposited to a thickness of 10 nm to form a hole blocking layer, and 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn) represented by the above structural formula (xviii) and 8-quinolinolato-lithium (abbreviation: Liq) represented by the above structural formula (vi) were co-deposited to a thickness of 15 nm in a weight ratio of 1:1 (=mPn-mDMePyPTzn:Liq) to form an electron transport layer 114.

[0429] After forming the electron transport layer 114, Liq was deposited to a thickness of 1 nm to form the electron injection layer 115, and finally, aluminum was evaporated to a thickness of 200 nm to form the cathode 102, thereby producing the light-emitting device 7.

[0430] The element structure of the light-emitting device 7 is summarized in the table below.

[0431] [Table 7]

[0432] Note that mmtBumTPoFBi-02 is a low-refractive-index hole-transport material whose ordinary refractive index is 1.69 to 1.70, ranging from 1.50 to 1.75, throughout the entire blue emission region (455 nm to 465 nm). Its ordinary refractive index at 633 nm is 1.64, ranging from 1.45 to 1.70. Bnf(II)PhA has an ordinary refractive index of 1.89 to 1.91 throughout the entire blue emission region (455 nm to 465 nm), and its ordinary refractive index at 633 nm is 1.79. Because the concentration of 3,10PCA2Nbf(IV)-02 in the light-emitting layer 113 is low, the refractive index of the light-emitting layer 113 is equivalent to that of Bnf(II)PhA. Therefore, the light-emitting device of one embodiment of the present invention is a light-emitting device in which the refractive index of the hole-transport layer 112 is lower than that of the light-emitting layer 113.

[0433] Furthermore, pmPCBBiBPDBt used in the electron blocking layer of light-emitting device 7 is a monoamine compound having a triarylamine structure that has a group containing a carbazole structure, a group containing a dibenzofuran structure or a dibenzothiophene structure, and a group containing an aromatic hydrocarbon structure having 6 to 18 carbon atoms.

[0434] The above light-emitting devices were sealed with glass substrates in a nitrogen-atmosphere glove box to prevent the light-emitting devices from being exposed to the atmosphere (a UV-curable sealant was applied around the elements, UV was irradiated only on the sealant without irradiating the light-emitting devices, and heat-treated at 80°C under atmospheric pressure for 1 hour), and then the initial characteristics of these light-emitting devices were measured.

[0435] The luminance-current density characteristics of light-emitting device 7 are shown in Figure 30, the luminance-voltage characteristics in Figure 31, the current efficiency-luminance characteristics in Figure 32, the current-voltage characteristics in Figure 33, the external quantum efficiency-luminance characteristics in Figure 34, the power efficiency-luminance characteristics in Figure 35, and the emission spectrum in Figure 36. 2 The main characteristics in this range are shown in Table 3. The luminance, CIE chromaticity, and emission spectrum were measured using a spectroradiometer (SR-UL1R, manufactured by Topcon Corporation) at room temperature.

[0436] [Table 8]

[0437] 30 to 36 and Table 8, it can be seen that the light-emitting device 7 of one embodiment of the present invention is a light-emitting element with good power efficiency because pmPCBBiBPDBt is provided in contact with the low-refractive-index material mmtBumTPoFBi-02, and therefore has good external quantum efficiency and a suppressed decrease in driving voltage.

[0438] In this way, a light-emitting device having a layer containing a monoamine compound having a specific structure formed in contact with a low refractive index layer can be a light-emitting device with good characteristics. Specifically, it can be a light-emitting device with a long life, good luminous efficiency, or a light-emitting device with a low driving voltage. [Example]

[0439] In this example, a light-emitting device 8 according to one embodiment of the present invention and a comparative light-emitting device 12, which are described in the embodiment, will be described. The structural formulae of organic compounds used in this example are shown below.

[0440] [ka]

[0441] (Method for fabricating light-emitting device 8) First, a silver (Ag) film was formed on a glass substrate by sputtering to a thickness of 100 nm as a reflective electrode, and then an indium tin oxide (ITSO) film containing silicon oxide was formed on the glass substrate by sputtering to a thickness of 10 nm as a transparent electrode to form an anode 101. The electrode area was 4 mm 2 (2mm x 2mm).

[0442] 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.

[0443] Then, 10 -4 The substrate was introduced into a vacuum deposition apparatus whose internal pressure had been reduced to about Pa, and after vacuum baking at 170°C for 30 minutes in the heating chamber of the vacuum deposition apparatus, the substrate was allowed to cool for about 30 minutes.

[0444] Next, the substrate on which the anode 101 was formed was fixed to a substrate holder installed in a vacuum deposition apparatus so that the surface on which the anode 101 was formed faced downward. N-3',5'-ditertiarybutyl-1,1'-biphenyl-4-yl-N-1,1'-biphenyl-2-yl-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBuBioFBi) represented by the above structural formula (xvi) and an electron acceptor material (OCHD-001) were co-deposited on the anode 101 by a deposition method to a thickness of 10 nm in a weight ratio of 1:0.1 (= mmtBumTPoFBi-02:OCHD-001) to form a hole injection layer 111.

[0445] On the hole injection layer 111, mmtBuBioFBi was evaporated to a thickness of 120 nm to form a hole transport layer 112.

[0446] Next, N-[4-(9H-carbazol-9-yl)phenyl]-N-[4-(4-dibenzofuranyl)phenyl]-[1,1':4',1''-terphenyl]-4-amine (abbreviation: YGTPDBfB) represented by the above structural formula (ii) was vapor-deposited on the hole transport layer 112 to a thickness of 10 nm to form an electron blocking layer.

[0447] Thereafter, 2-(10-phenyl-9-anthracenyl)-benzo[b]naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA) represented by the above structural formula (iii) and 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) represented by the above structural formula (iv) were co-deposited to a thickness of 25 nm in a weight ratio of 1:0.015 (=Bnf(II)PhA:3,10PCA2Nbf(IV)-02) to form the light-emitting layer 113.

[0448] Thereafter, 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)-1,1'-biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn) represented by the above structural formula (v) was deposited to a thickness of 10 nm to form a hole blocking layer, and 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn) represented by the above structural formula (xviii) and 8-quinolinolato-lithium (abbreviation: Liq) represented by the above structural formula (vi) were co-deposited to a thickness of 20 nm in a weight ratio of 1:1 (=mPn-mDMePyPTzn:Liq) to form an electron transport layer 114.

[0449] After forming the electron transport layer 114, lithium fluoride (LiF) was deposited to a thickness of 1 nm to form the electron injection layer 115. Finally, a cathode 102 was formed by co-evaporating silver (Ag) and magnesium (Mg) to a volume ratio of 1:0.1 and a film thickness of 15 nm, thereby producing a light-emitting device 8. The cathode 102 is a semi-transparent / semi-reflective electrode that has the functions of reflecting and transmitting light, and the light-emitting device of this example is a top-emission element that extracts light from the cathode 102. In addition, 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) represented by the above structural formula (xvii) was evaporated onto the cathode 102 to a thickness of 70 nm to improve extraction efficiency.

[0450] (Method for producing comparative light-emitting device 12) Comparative light-emitting device 12 was fabricated in the same manner as light-emitting device 8, except that mmtBuBioFBi in the hole injection layer and hole transport layer of light-emitting device 8 was replaced with N-(1,1'-biphenyl-4-yl)-9,9-dimethyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9H-fluoren-2-amine (abbreviation: PCBBiF) represented by the above structural formula (xii), and the thickness of the hole transport layer was set to 100 nm.

[0451] The device structures of light-emitting device 8 and comparative light-emitting device 12 are summarized in the table below.

[0452] [Table 9]

[0453] Note that mmtBuBioFBi is a low-refractive-index hole-transport material with an ordinary refractive index of 1.73 to 1.74 (1.50 to 1.75) throughout the entire blue emission region (455 nm to 465 nm), and a refractive index of 1.66 at 633 nm (1.45 to 1.70). Bnf(II)PhA has an ordinary refractive index of 1.89 to 1.91 throughout the entire blue emission region (455 nm to 465 nm), and a refractive index of 1.79 at 633 nm. Because the concentration of 3,10PCA2Nbf(IV)-02 in the light-emitting layer 113 is low, the refractive index of the light-emitting layer 113 is equivalent to that of Bnf(II)PhA. Therefore, the light-emitting device of one embodiment of the present invention is a light-emitting device in which the refractive index of the hole-transport layer 112 is lower than that of the light-emitting layer 113.

[0454] Furthermore, YGTPDBfB used in the electron blocking layer of light-emitting device 8 is a monoamine compound having a triarylamine structure having a group containing a carbazole structure, a group containing a dibenzofuran structure or a dibenzothiophene structure, and a group containing an aromatic hydrocarbon structure having 6 to 18 carbon atoms.

[0455] The above light-emitting devices were sealed with glass substrates in a nitrogen-atmosphere glove box to prevent the light-emitting devices from being exposed to the atmosphere (a UV-curable sealant was applied around the elements, UV was irradiated only on the sealant without irradiating the light-emitting devices, and heat-treated at 80°C under atmospheric pressure for 1 hour), and then the initial characteristics of these light-emitting devices were measured.

[0456] The luminance-current density characteristics of light-emitting device 8 and comparative light-emitting device 12 are shown in Figure 37, luminance-voltage characteristics in Figure 38, current efficiency-luminance characteristics in Figure 39, current-voltage characteristics in Figure 40, blue index-luminance characteristics in Figure 41, and emission spectra in Figure 42. The 1000 cd / m 2 The main characteristics in this range are shown in Table 10. The luminance, CIE chromaticity, and emission spectrum were measured using a spectroradiometer (SR-UL1R, manufactured by Topcon Corporation) at room temperature.

[0457] [Table 10]

[0458] 37 to 42 and Table 10 show that the light-emitting device 7 of one embodiment of the present invention is a light-emitting element with high emission efficiency because YGTPDBfB is provided in contact with mmtBuBioFBi, which is a low refractive index material.

[0459] In addition, the current density is 50mA / cm 2 A graph showing the change in luminance with respect to the driving time in this case is shown in Fig. 43. As shown in Fig. 43, it was found that light-emitting device 8 is a light-emitting device with a good lifespan.

[0460] In this way, a light-emitting device having a layer containing a monoamine compound having a specific structure formed in contact with a low refractive index layer can be a light-emitting device with good characteristics. Specifically, it can be a light-emitting device with good luminous efficiency, a light-emitting device with low driving voltage, or a light-emitting device with good lifespan. [Example]

[0461] <Synthesis Example 1> This example describes a synthesis method for 4-(dibenzothiophen-4-yl)-4'-phenyl-4''-(9-phenyl-9H-carbazol-2-yl)triphenylamine (abbreviation: PCBBiPDBt-02), which is a monoamine compound of one embodiment of the present invention and is represented by General Formula (G1) in Embodiment 1. The structure of PCBBiPDBt-02 is shown below.

[0462] [ka]

[0463] A 200 mL three-neck flask was charged with 1.8 g (3.7 mmol) of N-(4-biphenyl)-N-[4-(9-phenyl-9H-carbazol-2-yl)phenyl]amine, 1.1 g (3.4 mmol) of 4-(4-bromophenyl)dibenzothiophene, and 0.97 g (10 mmol) of sodium tert-butoxide. To this mixture was added 20 mL of toluene and 0.2 mL of a 10% hexane solution of tri(tert-butyl)phosphine. The mixture was degassed by stirring under reduced pressure. To this mixture was added 19 mg (34 μmol) of bis(dibenzylideneacetone)palladium(0), and the mixture was heated and stirred at 110 °C for 9 hours under a nitrogen stream.

[0464] After stirring, toluene was added to the mixture, and the mixture was suction filtered through Florisil, Celite, and alumina. The filtrate was concentrated to obtain a solid. The synthesis scheme of this synthesis example is shown below.

[0465] [ka]

[0466] This solid was purified by silica gel column chromatography (developing solvent: hexane:toluene=2:1) to obtain a solid, which was then recrystallized from ethyl acetate to obtain 2.6 g of a white solid in a yield of 94%.

[0467] The obtained solid (2.1 g) was purified by train sublimation under the conditions of a pressure of 3.1 Pa, an argon flow rate of 15 mL / min, and a temperature of 345° C. After the sublimation purification, 1.8 g of a white solid was obtained with a recovery rate of 86%.

[0468] The white solid obtained in the synthesis example was analyzed by nuclear magnetic resonance spectroscopy ( 1 The results of the analysis by H-NMR are shown in Figures 44A and 44B. Note that Figure 44B is a graph showing an enlarged view of the range from 7 ppm to 8.5 ppm in Figure 44A. Numerical data is also shown below. From this, it was found that PCBBiPDBt-02 was successfully synthesized in this synthesis example.

[0469] 1 H NMR (DMSO-d6,300MHz):δ=7.22-7.39(m,9H),7.42-7.49(m,3H),7.51-7.75(m,19H),8.03(dd,J1=6.0Hz,J2=3.3Hz,1H) ,8.28(d,J1=7.5Hz,1H),8.33(d,J1=8.1Hz,1H),8.37(dd,J1=7.5Hz,J2=1.2Hz,1H),8.41(dd,J1=6.0Hz,J2=3.0Hz,1H).

[0470] Next, the absorption and emission spectra of a toluene solution of PCBBiPDBt-02 were measured and shown in Figure 45, and the absorption and emission spectra of a thin film are shown in Figure 46. In the figures, the horizontal axis represents wavelength, the vertical axis represents absorbance and emission intensity, the thin solid line represents the absorption spectrum, and the thick solid line represents the emission spectrum. The absorbance shown in Figure 45 represents the result of subtracting the absorption spectrum measured by placing only toluene in a quartz cell from the absorption spectrum measured by placing the toluene solution in a quartz cell.

[0471] The solid thin film was prepared on a quartz substrate by vacuum deposition. The absorption spectrum of the toluene solution was measured using a UV-visible spectrophotometer (V550, manufactured by JASCO Corporation), and the spectrum measured with only toluene in a quartz cell was subtracted from the measured spectrum. The absorption spectrum of the thin film was measured using a spectrophotometer (U4100, manufactured by Hitachi High-Technologies Corporation). The emission spectrum was measured using a fluorometer (FS920, manufactured by Hamamatsu Photonics K.K.).

[0472] As shown in Figure 45, the toluene solution of PCBBiPDBt-02 exhibited absorption peaks at 355 nm and 282 nm, and emission peaks at 406 nm and 426 nm (excitation wavelength 357 nm). Also, as shown in Figure 46, the thin film of PCBBiPDBt-02 exhibited absorption peaks at 359 nm and 290 nm, and emission peak at 427 nm (excitation wavelength 360 nm).

[0473] Next, PCBBiPDBt-02 obtained in this example was analyzed by liquid chromatography mass spectrometry (LC / MS analysis).

[0474] In the LC / MS analysis, LC (liquid chromatography) separation was performed using an Ultimate 3000 manufactured by Thermo Fisher Scientific, and MS analysis (mass spectrometry) was performed using a Q Exactive manufactured by Thermo Fisher Scientific.

[0475] For LC separation, an arbitrary column was used, the column temperature was set to 40°C, and the solvent was appropriately selected as the flow condition. The sample was prepared by dissolving PCBBiPDBt-02 at an arbitrary concentration in an organic solvent, and the injection volume was 5.0 μL.

[0476] Targeted-MS 2 By the method, the MS of m / z=744.26, which is an ion derived from PCBBiPDBt-02, was 2 Measurement was performed using Targeted-MS. 2 The target ion mass range was m / z = 744.26 ± 2.0 (isolation window = 4), and detection was performed in positive mode. The target ion acceleration energy in the collision cell, NCE (Normalized Collision Energy), was set to 50. The obtained MS spectrum is shown in Figure 47.

[0477] From the results in Figure 47, it was found that when the collision energy was 50 eV, PCBBiPDBt-02 detected precursor ions mainly around 744, due to the presence or absence of hydrogen ions and isotopes, and product ions around m / z = 592, 486, 427, 333, 274, 242, and 168. The results shown in Figure 47 can be said to be important data for identifying PCBBiPDBt-02.

[0478] The product ion at m / z = 592 is presumed to be a cation from PCBBiPDBt-02 in which one biphenyl group has been removed, suggesting that PCBBiPDBt-02 contains a biphenyl group.

[0479] The product ion near m / z = 486 is presumed to be a cation in PCBBiPDBt-02 from which one 4-(dibenzothiophen-4-yl)phenyl group has been removed, suggesting that PCBBiPDBt-02 contains a 4-(dibenzothiophen-4-yl)phenyl group.

[0480] The product ion at m / z = 427 is presumed to be a cation from PCBBiPDBt-02 in which one 4-(9-phenyl-9H-carbazol-2-yl)phenyl group has been removed, suggesting that PCBBiPDBt-02 contains a 4-(9-phenyl-9H-carbazol-2-yl)phenyl group. [Example]

[0481] <Synthesis Example 2> Example 1 This example describes a synthesis method for 3-(dibenzothiophen-4-yl)-4'-phenyl-4''-(9-phenyl-9H-carbazol-2-yl)triphenylamine (abbreviation: mPCBBiPDBt-02), which is a monoamine compound of one embodiment of the present invention described in Embodiment 1. The structure of mPCBBiPDBt-02 is shown below.

[0482] [ka]

[0483] A 200 mL three-neck flask was charged with 1.8 g (3.7 mmol) of N-(4-biphenyl)-N-[4-(9-phenyl-9H-carbazol-2-yl)phenyl]amine, 1.1 g (3.4 mmol) of 4-(3-bromophenyl)dibenzothiophene, and 0.97 g (10 mmol) of sodium tert-butoxide. To this mixture was added 20 mL of toluene and 0.2 mL of a 10% hexane solution of tri(tert-butyl)phosphine. The mixture was degassed by stirring under reduced pressure. To this mixture was added 19 mg (34 μmol) of bis(dibenzylideneacetone)palladium(0), and the mixture was heated and stirred at 110 °C for 8 hours under a nitrogen stream. After stirring, toluene was added to the mixture, and the mixture was suction filtered through Florisil, Celite, and alumina to obtain a filtrate, which was then concentrated to obtain a solid.

[0484] [ka]

[0485] This solid was purified by silica gel column chromatography (developing solvent: hexane:toluene=2:1) to obtain a solid.

[0486] The resulting solid was recrystallized from toluene / ethyl acetate to give 2.3 g of a white solid in a yield of 91%. The resulting solid (2.3 g) was purified by train sublimation at 335°C under a pressure of 3.0 Pa and an argon flow rate of 15 mL / min. After purification by sublimation, 1.6 g of a white solid was obtained with a recovery rate of 69%.

[0487] The white solid obtained in the synthesis example was analyzed by nuclear magnetic resonance spectroscopy ( 1 The results of the analysis by H-NMR are shown in Figures 48A and 48B. Note that Figure 48B is a graph showing an enlarged view of the range from 7 ppm to 8.5 ppm in Figure 48A. Numerical data is also shown below. From this, it was found that mPCBBiPDBt-02 was successfully synthesized in this synthesis example.

[0488] 1 H NMR (DMSO-d6,300MHz): δ=7.17-7.72(m,31H),7.91-7.97(m,1H),8.27(d,J1=7.5Hz,1H),8.31(d,J1=8.1Hz,1H),8.35-8.41(m,2H).

[0489] Next, the absorption spectrum and emission spectrum of a toluene solution of mPCBBiPDBt-02 were measured, and the results are shown in Figure 49. The absorption spectrum and emission spectrum of the thin film are also shown in Figure 50. In the figure, the horizontal axis represents wavelength, the vertical axis represents absorbance and emission intensity, the thin solid line represents the absorption spectrum, and the thick solid line represents the emission spectrum. The absorbance shown in Figure 49 represents the result of subtracting the absorption spectrum measured by placing only toluene in a quartz cell from the absorption spectrum measured by placing the toluene solution in a quartz cell.

[0490] The solid thin film was prepared on a quartz substrate by vacuum deposition. The absorption spectrum of the toluene solution was measured using a UV-visible spectrophotometer (V550, manufactured by JASCO Corporation), and the spectrum measured with only toluene in a quartz cell was subtracted from the measured spectrum. The absorption spectrum of the thin film was measured using a spectrophotometer (U4100, manufactured by Hitachi High-Technologies Corporation). The emission spectrum was measured using a fluorometer (FS920, manufactured by Hamamatsu Photonics K.K.).

[0491] As shown in Figure 49, the toluene solution of mPCBBiPDBt-02 exhibited absorption peaks at 339 nm and 282 nm, and emission peaks at 401 nm and 420 nm (excitation wavelength 348 nm). Also, as shown in Figure 50, the thin film of mPCBBiPDBt-02 exhibited absorption peaks at 344 nm and 288 nm, and emission peak at 420 nm (excitation wavelength 360 nm).

[0492] Next, mPCBBiPDBt-02 obtained in this example was analyzed by liquid chromatography mass spectrometry (LC / MS analysis).

[0493] In the LC / MS analysis, LC (liquid chromatography) separation was performed using an Ultimate 3000 manufactured by Thermo Fisher Scientific, and MS analysis (mass spectrometry) was performed using a Q Exactive manufactured by Thermo Fisher Scientific.

[0494] For LC separation, an arbitrary column was used, the column temperature was set to 40°C, and the solvent was appropriately selected as the flow condition. The sample was prepared by dissolving mPCBBiPDBt-02 at an arbitrary concentration in an organic solvent, and the injection volume was 5.0 μL.

[0495] Targeted-MS 2 By the method, the MS of m / z=744.26, which is an ion derived from mPCBBiPDBt-02, was 2 Measurement was performed using Targeted-MS. 2The target ion mass range was m / z = 744.26 ± 2.0 (isolation window = 4), and detection was performed in positive mode. The energy used to accelerate the target ions in the collision cell, NCE (Normalized Collision Energy), was set to 50. The obtained MS spectrum is shown in Figure 51.

[0496] From the results in Figure 51, it was found that when the collision energy was 50 eV, precursor ions were detected mainly around 744 for mPCBBiPDBt-02, due to the presence or absence of hydrogen ions and isotopes, and product ions were detected around m / z = 592, 486, 427, 333, 319, 242, and 168. The results shown in Figure 51 can be said to be important data for identifying mPCBBiPDBt-02.

[0497] The product ion at m / z=592 is presumed to be a cation in which one biphenyl group has been removed from mPCBBiPDBt-02, suggesting that mPCBBiPDBt-02 contains a biphenyl group.

[0498] The product ion at m / z = 486 is presumed to be a cation in mPCBBiPDBt-02 from which one 3-(dibenzothiophen-4-yl)phenyl group has been removed, suggesting that mPCBBiPDBt-02 contains a 3-(dibenzothiophen-4-yl)phenyl group.

[0499] The product ion at m / z = 427 is presumed to be a cation in mPCBBiPDBt-02 from which one 4-(9-phenyl-9H-carbazol-2-yl)phenyl group has been removed, suggesting that mPCBBiPDBt-02 contains a 4-(9-phenyl-9H-carbazol-2-yl)phenyl group. [Example]

[0500] <Synthesis Example 3> Example 1 This example describes a synthesis method for 4-[3-(dibenzothiophen-4-yl)phenyl]-4'-phenyl-4''-(9-phenyl-9H-carbazol-2-yl)triphenylamine (abbreviation: pmPCBBiBPDBt-02), which is a monoamine compound of one embodiment of the present invention described in Embodiment 1. The structure of pmPCBBiBPDBt-02 is shown below.

[0501] [ka]

[0502] A 200 mL three-neck flask was charged with 1.6 g (3.4 mmol) of N-(4-biphenyl)-N-[4-(9-phenyl-9H-carbazol-2-yl)phenyl]amine, 1.3 g (3.0 mmol) of 4-(4'-bromo[1,1'-biphenyl]-3-yl)dibenzothiophene, and 0.88 g (9.1 mmol) of sodium tert-butoxide. To this mixture was added 20 mL of toluene and 0.2 mL of a 10% hexane solution of tri(tert-butyl)phosphine. The mixture was degassed by stirring under reduced pressure. To this mixture was added 17 mg (30 μmol) of bis(dibenzylideneacetone)palladium(0), and the mixture was heated and stirred at 110 °C for 12 hours under a nitrogen stream.

[0503] After stirring, toluene was added to the mixture, and the mixture was suction filtered through Florisil, Celite, and alumina to obtain a filtrate. The filtrate was concentrated to obtain a solid. The synthesis scheme of this synthesis example is shown below.

[0504] [ka]

[0505] This solid was purified by silica gel column chromatography (developing solvent: hexane:toluene=2:1) to obtain a solid, which was then reprecipitated with toluene / ethanol to obtain 2.3 g of a solid in a yield of 91%.

[0506] The resulting solid (2.3 g) was purified by train sublimation at 385°C under a pressure of 3.0 Pa and an argon flow rate of 15 mL / min. After purification by sublimation, 2.0 g of a white solid was obtained with a recovery rate of 85%.

[0507] The white solid obtained in this synthesis example was analyzed by nuclear magnetic resonance spectroscopy ( 1 The results of the analysis by H-NMR are shown in Figures 52A and 52B. Note that Figure 52B is a graph showing an enlarged view of the range from 7 ppm to 8.5 ppm in Figure 52A. Numerical data is also shown below. From this, it was found that pmPCBBiBPDBt-02 was synthesized in this synthesis example.

[0508] 1 H NMR(DMSO-d6,300MHz):δ=7.17-7.20(m,6H),7.28-7.47(m,6H),7.51-7.80(m,22H), 7.99-8.05(m,2H),8.27(d,J1=7.5Hz,1H),8.32(d,J1=8.4Hz,1H),8.39-8.46(m,2H).

[0509] Next, the absorption and emission spectra of a toluene solution of pmPCBBiBPDBt-02 were measured, and the results are shown in Figure 53, and the absorption and emission spectra of a thin film are shown in Figure 54. In the figures, the horizontal axis represents wavelength, the vertical axis represents absorbance and emission intensity, with the thin solid line representing the absorption spectrum and the thick solid line representing the emission spectrum. The absorbance shown in Figure 53 represents the result of subtracting the absorption spectrum measured by placing only toluene in a quartz cell from the absorption spectrum measured by placing the toluene solution in a quartz cell.

[0510] The solid thin film was prepared on a quartz substrate by vacuum deposition. The absorption spectrum of the toluene solution was measured using a UV-visible spectrophotometer (V550, manufactured by JASCO Corporation), and the spectrum measured with only toluene in a quartz cell was subtracted from the measured spectrum. The absorption spectrum of the thin film was measured using a spectrophotometer (U4100, manufactured by Hitachi High-Technologies Corporation). The emission spectrum was measured using a fluorometer (FS920, manufactured by Hamamatsu Photonics K.K.).

[0511] As shown in Figure 53, the pmPCBBiBPDBt-02 toluene solution exhibited absorption peaks at 355 nm, 298 nm, and 282 nm, with an emission peak at 407 nm (excitation wavelength 356 nm). Also, as shown in Figure 54, the pmPCBBiBPDBt-02 thin film exhibited absorption peaks at 358 nm and 289 nm, with an emission peak at 425 nm (excitation wavelength 360 nm).

[0512] Next, pmPCBBiBPDBt-02 obtained in this example was analyzed by liquid chromatography mass spectrometry (LC / MS analysis).

[0513] In the LC / MS analysis, LC (liquid chromatography) separation was performed using an Ultimate 3000 manufactured by Thermo Fisher Scientific, and MS analysis (mass spectrometry) was performed using a Q Exactive manufactured by Thermo Fisher Scientific.

[0514] For LC separation, an arbitrary column was used, the column temperature was set to 40°C, and the solvent was appropriately selected as the flow condition. The sample was prepared by dissolving pmPCBBiBPDBt-02 at an arbitrary concentration in an organic solvent, and the injection volume was 5.0 μL.

[0515] Targeted-MS 2 By the MS method, the ion m / z=820.29 derived from pmPCBBiBPDBt-02 was identified. 2 Measurement was performed using Targeted-MS. 2The target ion mass range was m / z = 820.29 ± 2.0 (isolation window = 4), and detection was performed in positive mode. The energy used to accelerate the target ions in the collision cell, NCE (Normalized Collision Energy), was set to 50. The MS spectrum obtained is shown in Figure 55.

[0516] From the results in Figure 55, it was found that when the collision energy was 50 eV, pmPCBBiBPDBt-02 detected precursor ions mainly around 820 due to the presence or absence of hydrogen ions and isotopes, and product ions were detected around m / z = 668, 503, 486, 408, 333, 243, and 168. The results shown in Figure 55 can be said to be important data for identifying pmPCBBiBPDBt-02.

[0517] The product ion near m / z=668 is presumed to be a cation in pmPCBBiBPDBt-02 from which one biphenyl group has been removed, suggesting that pmPCBBiBPDBt-02 contains a biphenyl group.

[0518] The product ion near m / z = 503 is presumed to be a cation in pmPCBBiBPDBt-02 from which one 4-(9-phenyl-9H-carbazol-2-yl)phenyl group has been removed, suggesting that pmPCBBiBPDBt-02 contains a 4-(9-phenyl-9H-carbazol-2-yl)phenyl group.

[0519] The product ion near m / z=486 is presumed to be a cation in pmPCBBiBPDBt-02 from which one 4-[3-(dibenzothiophen-4-yl)phenyl]phenyl group has been removed, suggesting that pmPCBBiBPDBt-02 contains a 4-[3-(dibenzothiophen-4-yl)phenyl]phenyl group. [Example]

[0520] <Synthesis Example 4> This example describes a synthesis method for 4-[3-(dibenzothiophen-4-yl)phenyl]-4′-phenyl-4″-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: pmPCBBiBPDBt), which is a monoamine compound of one embodiment of the present invention described in Embodiment 1. The structure of pmPCBBiBPDBt is shown below.

[0521] [ka]

[0522] A 200 mL three-neck flask was charged with 1.6 g (3.4 mmol) of N-biphenyl-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]amine, 1.3 g (3.0 mmol) of 4-[3-(4-bromophenyl)phenyl]dibenzothiophene, and 0.88 g (9.1 mmol) of sodium tert-butoxide. To this mixture was added 20 mL of toluene and 0.2 mL of a 10% hexane solution of tri(tert-butyl)phosphine. The mixture was degassed by stirring under reduced pressure. To this mixture was added 17 mg (30 μmol) of bis(dibenzylideneacetone)palladium(0), and the mixture was heated and stirred at 120 °C for 7.5 hours under a nitrogen stream.

[0523] After stirring, toluene was added to the mixture, and the mixture was suction filtered through Florisil, Celite, and alumina to obtain a filtrate. The filtrate was concentrated to obtain a solid. The synthesis scheme of this synthesis example is shown below.

[0524] [ka]

[0525] This solid was purified by silica gel column chromatography (developing solvent: hexane:toluene=2:1, then hexane:toluene=3:2) to obtain a solid, which was then recrystallized from toluene / ethyl acetate to obtain 2.2 g of a white solid in 86% yield.

[0526] The resulting solid (2.0 g) was purified by train sublimation at 380°C under a pressure of 3.2 Pa and an argon flow rate of 15 mL / min. After purification by sublimation, 1.7 g of a pale yellow solid was obtained with a recovery rate of 85%.

[0527] The white solid obtained in this synthesis example was analyzed by nuclear magnetic resonance spectroscopy ( 1 The results of the analysis by H-NMR are shown in Figures 56A and 56B. Note that Figure 56B is a graph showing an enlarged view of the range from 7 ppm to 9 ppm in Figure 56A. Numerical data is also shown below. From this, it was found that pmPCBBiBPDBt was synthesized in this synthesis example.

[0528] 1 H NMR(DMSO-d6,300MHz):δ=7.20-7.48(m,13H),7.51-7.59(m,3H),7.63-7.81(m,18H), 8.00-8.05(m,2H),8.35(d,J1=7.5Hz,1H),8.40-8.46(m,2H),8.59(d,J1=1.5Hz,1H).

[0529] Next, the absorption and emission spectra of a toluene solution of pmPCBBiBPDBt were measured, and the results are shown in Figure 57. The absorption and emission spectra of the thin film are shown in Figure 58. In the figure, the horizontal axis represents wavelength, the vertical axis represents absorbance and emission intensity, the thin solid line represents the absorption spectrum, and the thick solid line represents the emission spectrum. The absorbance shown in Figure 57 is the result of subtracting the absorption spectrum measured by placing only toluene in a quartz cell from the absorption spectrum measured by placing the toluene solution in a quartz cell.

[0530] The solid thin film was prepared on a quartz substrate by vacuum deposition. The absorption spectrum of the toluene solution was measured using a UV-visible spectrophotometer (V550, manufactured by JASCO Corporation), and the spectrum measured with only toluene in a quartz cell was subtracted from the measured spectrum. The absorption spectrum of the thin film was measured using a spectrophotometer (U4100, manufactured by Hitachi High-Technologies Corporation). The emission spectrum was measured using a fluorometer (FS920, manufactured by Hamamatsu Photonics K.K.).

[0531] As shown in Figure 57, the pmPCBBiBPDBt toluene solution exhibited absorption peaks at 349 nm and 282 nm, and the emission wavelength peak was 404 nm (excitation wavelength 354 nm). Also, as shown in Figure 58, the pmPCBBiBPDBt thin film exhibited absorption peaks at 351 nm and 285 nm, and the emission wavelength peak was 425 nm (excitation wavelength 370 nm). [Example]

[0532] <Synthesis Example 5> This example describes a synthesis method for 4-[3-(dibenzofuran-4-yl)phenyl]-4′-phenyl-4″-(9-phenyl-9H-carbazol-2-yl)triphenylamine (abbreviation: pmPCBBiBPDBf-02), which is a monoamine compound of one embodiment of the present invention described in Embodiment 1. The structure of pmPCBBiBPDBf-02 is shown below.

[0533] [ka]

[0534] A 200 mL three-neck flask was charged with 1.7 g (3.4 mmol) of N-biphenyl-[4-(9-phenyl-9H-carbazol-2-yl)phenyl]amine, 1.2 g (3.1 mmol) of 4-[3-(4-bromophenyl)phenyl]dibenzofuran, and 0.90 g (9.3 mmol) of sodium tert-butoxide. To this mixture was added 20 mL of toluene and 0.2 mL of a 10% hexane solution of tri(tert-butyl)phosphine. The mixture was degassed by stirring under reduced pressure. To this mixture was added 18 mg (31 μmol) of bis(dibenzylideneacetone)palladium(0), and the mixture was heated and stirred at 120 °C for 7 hours under a nitrogen stream.

[0535] After stirring, toluene was added to the mixture, and the mixture was suction filtered through Florisil, Celite, and alumina to obtain a filtrate. The filtrate was concentrated to obtain a solid. The synthesis scheme of this synthesis example is shown below.

[0536] [ka]

[0537] This solid was purified by silica gel column chromatography (developing solvent: hexane:toluene=2:1) to obtain a solid, which was then reprecipitated with ethyl acetate / ethanol to obtain 2.2 g of a white solid in a yield of 87%.

[0538] The resulting solid (2.1 g) was purified by train sublimation. The purification was carried out by heating at 370°C under a pressure of 3.3 Pa and an argon flow rate of 15 mL / min. After the purification by sublimation, 1.9 g of a white solid was obtained with a recovery rate of 87%.

[0539] The white solid obtained in this synthesis example was analyzed by nuclear magnetic resonance spectroscopy ( 1 The results of the analysis by H-NMR are shown in Figures 59A and 59B. Note that Figure 59B is a graph showing an enlarged view of the range from 7 ppm to 8.5 ppm in Figure 59A. Numerical data is also shown below. From this, it was found that pmPCBBiBPDBf-02 was successfully synthesized in this synthesis example.

[0540] 1 H NMR (DMSO-d6,300MHz): δ=7.18-7.22(m,6H),7.28-7.82(m,28H),7.88(d,J1=7.5Hz,1H),8.14-8.28(m,4H),8.32(d,J1=8.4Hz,1H).

[0541] Next, Figure 60 shows the results of measuring the absorption spectrum and emission spectrum of a toluene solution of pmPCBBiBPDBf-02. Figure 61 also shows the absorption spectrum and emission spectrum of the thin film. In the figure, the horizontal axis represents wavelength, the vertical axis represents absorbance and emission intensity, the thin solid line represents the absorption spectrum, and the thick solid line represents the emission spectrum. The absorbance shown in Figure 60 is the result of subtracting the absorption spectrum measured by placing only toluene in a quartz cell from the absorption spectrum measured by placing the toluene solution in a quartz cell.

[0542] The solid thin film was prepared on a quartz substrate by vacuum deposition. The absorption spectrum of the toluene solution was measured using a UV-visible spectrophotometer (V550, manufactured by JASCO Corporation), and the spectrum measured with only toluene in a quartz cell was subtracted from the measured spectrum. The absorption spectrum of the thin film was measured using a spectrophotometer (U4100, manufactured by Hitachi High-Technologies Corporation). The emission spectrum was measured using a fluorometer (FS920, manufactured by Hamamatsu Photonics K.K.).

[0543] As shown in Figure 60, the pmPCBBiBPDBf-02 toluene solution exhibited absorption peaks at 354 nm and 282 nm, and emission peaks at 407 nm and 423 nm (excitation wavelength 360 nm). Also, as shown in Figure 61, the pmPCBBiBPDBf-02 thin film exhibited absorption peaks at 358 nm, 293 nm, and 255 nm, and emission peaks at 424 nm and 440 nm (excitation wavelength 370 nm). [Example]

[0544] <Synthesis Example 6> This example describes a synthesis method for N-biphenyl-4-yl-N-[3-(dibenzothiophen-4-yl)biphenyl-4-yl]-9-phenyl-9H-carbazol-2-amine (abbreviation: pmPCBiBPDBt-02), which is a monoamine compound of one embodiment of the present invention described in Embodiment 1. The structure of pmPCBiBPDBt-02 is shown below.

[0545] [ka]

[0546] A 200 mL three-neck flask was charged with 1.9 g (3.7 mmol) of 4-phenyl-4'-[3-(dibenzothiophen-2-yl)phenyl]diphenylamine, 1.1 g (3.4 mmol) of 2-bromo-9-phenyl-9H-carbazole, and 1.1 g (11 mmol) of sodium tert-butoxide. To this mixture was added 20 mL of toluene and 0.2 mL of a 10% hexane solution of tri(tert-butyl)phosphine. The mixture was degassed by stirring under reduced pressure. To this mixture was added 19 mg (34 μmol) of bis(dibenzylideneacetone)palladium(0), and the mixture was heated and stirred at 120 °C for 7 hours under a nitrogen stream. After stirring, toluene was added to the mixture, which was then suction filtered through Florisil, Celite, and alumina to obtain the filtrate. The filtrate was concentrated to obtain a solid. The synthetic scheme for this synthesis example is shown below.

[0547] [ka]

[0548] This solid was purified by silica gel column chromatography (developing solvent: hexane:toluene=2:1) to obtain a solid, which was then reprecipitated with ethyl acetate / ethanol to obtain 2.1 g of a white solid in a yield of 85%.

[0549] The resulting solid (2.1 g) was purified by train sublimation. The purification was carried out by heating at 345°C under a pressure of 3.4 Pa and an argon flow rate of 15 mL / min. After sublimation purification, 1.9 g of a pale yellow solid was obtained, with a recovery rate of 88%.

[0550] The white solid obtained in this synthesis example was analyzed by nuclear magnetic resonance spectroscopy ( 1 The results of the analysis by H-NMR are shown in Figures 62A and 62B. Note that Figure 62B is a graph showing an enlarged view of the range from 7 ppm to 8.5 ppm in Figure 62A. Numerical data is also shown below. From this, it was found that pmPCBiBPDBt-02 was successfully synthesized in this synthesis example.

[0551] 1 H NMR (DMSO-d6,300MHz):δ=7.05-7.10(m,2H),7.17(d,J1=8.1Hz,4H),7.26-7.46(m ,7H),7.51-7.78(m,17H),7.99-8.04(m,2H),8.18-8.24(m,2H),8.39-8.45(m,2H).

[0552] Next, the absorption spectrum and emission spectrum of a toluene solution of pmPCBiBPDBt-02 were measured, and the results are shown in Figure 63. The absorption spectrum and emission spectrum of the thin film are shown in Figure 64. In the figure, the horizontal axis represents wavelength, the vertical axis represents absorbance and emission intensity, with the thin solid line representing the absorption spectrum and the thick solid line representing the emission spectrum. The absorbance shown in Figure 63 represents the result of subtracting the absorption spectrum measured by placing only toluene in a quartz cell from the absorption spectrum measured by placing the toluene solution in a quartz cell.

[0553] The solid thin film was prepared on a quartz substrate by vacuum deposition. The absorption spectrum of the toluene solution was measured using a UV-visible spectrophotometer (V550, manufactured by JASCO Corporation), and the spectrum measured with only toluene in a quartz cell was subtracted from the measured spectrum. The absorption spectrum of the thin film was measured using a spectrophotometer (U4100, manufactured by Hitachi High-Technologies Corporation). The emission spectrum was measured using a fluorometer (FS920, manufactured by Hamamatsu Photonics K.K.).

[0554] As shown in Figure 63, the pmPCBiBPDBt-02 toluene solution exhibited absorption peaks at 357 nm and 283 nm, and the emission wavelength peak was 405 nm (excitation wavelength 363 nm). Also, as shown in Figure 64, the pmPCBiBPDBt-02 thin film exhibited absorption peaks at 362 nm, 292 nm, and 270 nm, and the emission wavelength peak was 423 nm (excitation wavelength 363 nm). [Example]

[0555] <Synthesis Example 7> Example 1 This example describes a synthesis method for N-(3',5'-ditertiarybutyl-1,1'-biphenyl-4-yl)-N-(1,1'-biphenyl-2-yl)-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: mmtBuBioFBi), which is an organic compound according to one embodiment of the present invention described in Embodiment 1. The structure of mmtBuBioFBi is shown below.

[0556] [ka]

[0557] A three-neck flask was charged with 2.22 g (7.4 mmol) of 4-chloro-3',5'-di-tert-butyl-1,1'-biphenyl, 2.94 g (8.1 mmol) of 2-(2-biphenylyl)amino-9,9-dimethylfluorene, 2.34 g (24.4 mmol) of sodium tert-butoxide, and 37 mL of xylene. The flask was degassed under reduced pressure and then purged with nitrogen. To this mixture was added 107.6 mg (0.31 mmol) of di-t-butyl(1-methyl-2,2-diphenylcyclopropyl)phosphine (abbreviated as cBRIDP®) and 28.1 mg (0.077 mmol) of allylpalladium chloride dimer. The mixture was heated at 100°C for approximately 4 hours. The flask was then returned to approximately 70°C, and approximately 4 mL of water was added to precipitate a solid. The precipitated solid was collected by filtration. The filtrate was concentrated, and the resulting solution was purified by silica gel column chromatography. The resulting solution was concentrated, ethanol was added, and the concentration was repeated three times, followed by recrystallization as an ethanol suspension. After cooling to approximately -10°C, the precipitate was filtered, and the resulting solid was dried under reduced pressure at approximately 130°C to obtain 2.07 g of the target white solid in a 45% yield. The synthesis scheme of this synthesis example is shown below.

[0558] [ka]

[0559] The white solid obtained in this synthesis example was analyzed by nuclear magnetic resonance spectroscopy ( 1 The results of the analysis by H-NMR are shown in Figures 65A and 65B. Note that Figure 65B is a graph showing an enlarged view of the range from 6.5 ppm to 8 ppm in Figure 65A. Numerical data is also shown below. This demonstrates that mmtBuBioFBi was successfully synthesized in this synthesis example.

[0560] 1H NMR(CDCl3,500MHz):δ=1.29(s,6H),1.38(s,18H),6.76(dd,J1=8.0Hz,J2=2.0Hz,1H),6.87(d, J=2.5Hz,1H),7.00-7.08(m,5H),7.18-7.23(m,3H),7.27-7.43(m,12H),7.55(d,J=7.5Hz,1H).

[0561] Next, 2.0 g of the obtained solid was purified by train sublimation. The sublimation purification was carried out under conditions of a pressure of 3.77 Pa, an argon flow rate of 15.0 mL / min, and heating at 225 °C. After sublimation purification, 1.9 g of a white solid was obtained with a recovery rate of 95%.

[0562] Next, the absorption spectrum and emission spectrum of a toluene solution of mmtBuBioFBi were measured, and the results are shown in Figure 66. In the figure, the horizontal axis represents wavelength, the vertical axis represents absorbance and emission intensity, the thin solid line represents the absorption spectrum, and the thick solid line represents the emission spectrum. The absorbance shown in Figure 66 is the result of subtracting the absorption spectrum measured by placing only toluene in a quartz cell from the absorption spectrum measured by placing the toluene solution in a quartz cell.

[0563] The absorption spectrum of the toluene solution was measured using a UV-visible spectrophotometer (V550, manufactured by JASCO Corporation) and the spectrum measured with toluene alone in a quartz cell was subtracted from the absorption spectrum. The emission spectrum was measured using a fluorometer (FP-8600, manufactured by JASCO Corporation).

[0564] As shown in FIG. 66, the toluene solution of mmtBuBioFBi exhibited an absorption peak at 344 nm, and the emission wavelength peak was 397 nm (excitation wavelength 344 nm).

[0565] The refractive index of mmtBuBioFBi was measured using a spectroscopic ellipsometer (M-2000U manufactured by J.A. Woollam Japan Co., Ltd.) using a quartz substrate on which the materials for each layer were deposited by vacuum deposition to a thickness of approximately 50 nm.

[0566] As a result, it was found that mmtBuBioFBi has an ordinary refractive index in the range of 1.50 to 1.75 throughout the entire blue emission region (455 nm to 465 nm), and an ordinary refractive index in the range of 1.45 to 1.70 at 633 nm, making it a low refractive index material.

[0567] Next, the Tg of mmtBuBioFBi was measured. Tg was measured using a differential scanning calorimeter (PYRIS1DSC, manufactured by PerkinElmer Japan Co., Ltd.) by placing the powder in an aluminum cell. As a result, the Tg of mmtBuBioFBi was found to be 100°C. [Explanation of symbols]

[0568] 101: anode, 102: cathode, 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, 120: hole transport region, 400: substrate, 401: anode, 403: EL layer, 404: cathode, 405: sealing material, 406: sealing material, 407: sealing substrate, 412: pad, 420: IC chip, 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: anode, 614: insulator, 616: EL layer, 617: cathode, 618: light emitting device, 951: substrate, 952: electrode, 953: insulating layer, 954: partition layer, 955: EL layer, 956: electrode, 1001: substrate, 1002: base 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: anode, 1024R: anode, 1024G: anode, 1024B: anode, 1025: partition wall, 1028: EL layer, 1029: cathode, 1031: sealing substrate, 1032: sealing material, 1033: transparent base material, 1034R: red colored layer, 1034G: green colored layer, 1034B: blue colored layer, 1035: black matrix, 1036: overcoat layer, 1037: third interlayer insulating film, 1040: pixel section, 1041: drive circuit section, 1042: peripheral section, 2001: housing, 2002: light source, 21 00: 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: Mobile 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 unit, 7105: Stand, 7107: Display unit, 7109: Operation key, 7110: Remote control operation device, 7201 :Main body, 7202:Housing, 7203:Display unit, 7204:Keyboard, 7205:External connection port, 7206:Pointing device, 7210:Display unit, 7401:Housing, 7402:Display unit, 7403:Operation buttons, 7404:External connection port, 7405:Speaker, 7406:Microphone, 9310:Mobile information terminal, 9311:Display panel, 9313:Hinge, 9315:Housing,

Claims

[Claim 1] an anode; A cathode; an EL layer located between the anode and the cathode; the EL layer includes a light-emitting layer, a first layer, and a second layer; the first layer is located between the anode and the light-emitting layer; the first layer and the second layer are in contact with each other; the second layer includes a first organic compound having an arylamine structure; the first organic compound has a first group, a second group, and a third group bonded to a nitrogen atom constituting the amine; the first group is a group containing a carbazole structure, the second group is a group containing a dibenzofuran structure or a dibenzothiophene structure, the third group contains an aromatic hydrocarbon structure having 6 to 18 carbon atoms or a heteroaromatic hydrocarbon structure having 4 to 26 carbon atoms, A light emitting device wherein the refractive index of the first layer is lower than the refractive index of the light emitting layer.

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