Light-emitting devices

Abstract

To provide an organic compound capable of providing a light-emitting device with high light emission efficiency and reliability.SOLUTION: There is provided an organic compound represented by a general formula (G1-1). In the general formula (G1-1), R1 to R10 are each independently one of an alkyl group of 3 to 10 in hydrogen, carbon number and a substituted or unsubstituted cycloalkyl group of 3 to 10 in carbon number, and Ar1 and Ar2 are each independently an aromatic hydrocarbon group of 6 to 13 in carbon number having a substituent group. Here, Ar1 and Ar2 each have at least one or more of a cycloalkyl group of 3 to 12 in carbon number and a cycloalkyl group of 7 to 10 in carbon number with a bridge structure as the substituent group.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] One embodiment of the present invention relates to a light-emitting device, an organic compound, or a display device, an electronic device, and a lighting device each including the light-emitting device.

[0002] 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 relates to an object, a method, or a manufacturing method. Alternatively, one embodiment of the present invention relates to a process, a machine, a 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, and driving methods thereof or manufacturing methods thereof. [Background technology]

[0003] In recent years, research and development of light-emitting devices that utilize electroluminescence (EL) has been actively conducted. The basic structure of these light-emitting devices is a layer containing a light-emitting substance (EL layer) sandwiched between a pair of electrodes. By applying a voltage between these electrodes, light can be emitted from the light-emitting substance.

[0004] Since the above-mentioned light-emitting device is a self-luminous type, a display device using it has the characteristics of excellent visibility, no need for a backlight, low power consumption, etc. Furthermore, it has the advantages of being thin and lightweight, and having a high response speed.

[0005] In such a light-emitting device, when a voltage is applied between a pair of electrodes, electrons from the cathode and holes from the anode are injected into the EL layer, causing a current to flow. The injected electrons and holes then recombine, exciting the luminescent material and producing light.

[0006] When the luminescent substance is an organic compound, the type of excited state that the organic compound forms includes a singlet excited state (S * ) and triplet excited states (T * ) and emission from the singlet excited state is called fluorescence, and emission from the triplet excited state is called phosphorescence. The statistical generation ratio of these excited states in the above light-emitting devices, which are excited by electric current, is S * :T * Therefore, it is easier to obtain light-emitting devices with high luminous efficiency by using phosphorescent materials, which convert triplet excited state energy into luminescence, rather than fluorescent materials, which convert singlet excited state energy into luminescence. Therefore, the development of light-emitting devices using phosphorescent materials has been actively pursued in recent years.

[0007] However, among light-emitting devices using phosphorescent materials, particularly those that emit blue light, the development of stable compounds with high triplet excitation energy levels has been extremely difficult, and they have not yet been put to practical use. Therefore, active development is being conducted on light-emitting devices that use stable fluorescent materials and exhibit high luminous efficiency, primarily for application in blue light-emitting devices.

[0008] In addition to phosphorescent materials, thermally activated delayed fluorescence (TADF) materials are known as materials capable of converting the energy of triplet excited states into luminescence. TADF materials generate singlet excited states from triplet excited states through reverse intersystem crossing, and emit light from the singlet excited states.

[0009] To increase the luminescence efficiency of light-emitting devices that use TADF materials as luminescent materials, it is important not only to efficiently generate a singlet excited state from the triplet excited state of the TADF material, but also to efficiently emit light from the generated singlet excited state, i.e., to have a high fluorescence quantum yield of the TADF material itself. However, it is not easy to design a luminescent material that satisfies both of these requirements simultaneously.

[0010] Regarding this problem, Patent Document 1 proposes a light-emitting device in which a TADF material is used as a host material and a fluorescent material as a guest material (light-emitting material), and the TADF material converts triplet excitation energy into singlet excitation energy, which is then transferred to the fluorescent material, resulting in light emission from the fluorescent material. Because triplet excitation energy also contributes to light emission, such a light-emitting device can achieve high luminous efficiency even when the light-emitting material is a fluorescent material, and because the fluorescent material used as the light-emitting material is stable, it can also achieve a longer lifespan than phosphorescent light-emitting devices. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-45179 [Non-patent literature]

[0012] [Non-Patent Document 1] Hiroki Uoyama et al., “Nature”, 2012, vol. 492, 234 Summary of the Invention [Problem to be solved by the invention]

[0013] One method for improving the efficiency of fluorescent light-emitting devices is to use an emission layer containing a host material, such as a TADF material, that can convert triplet excitation energy into singlet excitation energy, and a fluorescent guest material, as described in Patent Document 1, and convert the triplet excitons of the host material into singlet excitons, and then transfer the singlet excitation energy to the fluorescent guest material.

[0014] However, in this method, the process of converting the triplet excitation energy of the host material to singlet excitation energy competes with the process of deactivation of the triplet excitation energy, and therefore the triplet excitation energy of the host material is not sufficiently converted to singlet excitation energy, and the expected efficiency improvement effect may not be obtained.

[0015] One of the processes by which such triplet excitation energy is deactivated is a pathway in which the triplet excitation energy of the host material is transferred to the lowest triplet excitation energy level (T1 level) of the fluorescent guest material.

[0016] This deactivation pathway can be suppressed by reducing the concentration of the guest material. However, this also suppresses the energy transfer from the host material to the singlet excited state of the guest material, making quenching due to degradation products and impurities more likely to occur, resulting in reduced luminous efficiency and reliability.

[0017] Therefore, an object of one embodiment of the present invention is to provide an organic compound that can realize a fluorescent light-emitting device with good emission efficiency and lifetime. Another object of one embodiment of the present invention is to provide an organic compound that can be used as a guest material in a host material and a guest material in an emission layer of a light-emitting device, by suppressing the transfer of triplet excitation energy of the host material to the T1 level of the fluorescent guest material and efficiently converting the triplet excitation energy of the host material into singlet excitation energy of the guest material, thereby improving the emission efficiency of the fluorescent light-emitting device. Another object of one embodiment of the present invention is to provide an organic compound that can realize a light-emitting device with good emission efficiency and excellent reliability.

[0018] Another object of one embodiment of the present invention is to provide a light-emitting device that can suppress the transfer of triplet excitation energy of the host material to the T1 level of the fluorescent guest material in a host material and a guest material in an emission layer, efficiently convert the triplet excitation energy of the host material into singlet excitation energy of the guest material, and thereby improve the fluorescence emission efficiency of the light-emitting device. Another object of one embodiment of the present invention is to provide a light-emitting device that has good emission efficiency and excellent reliability. Another object of one embodiment of the present invention is to provide a light-emitting device that has good color purity. Another object of one embodiment of the present invention is to provide a light-emitting device that has good color purity and good emission efficiency.

[0019] Another object of one embodiment of the present invention is to provide a light-emitting device with reduced power consumption.Another object of one embodiment of the present invention is to provide a novel light-emitting device.Another object of one embodiment of the present invention is to provide a novel light-emitting device.Another object of one embodiment of the present invention is to provide a novel display device.Another object of one embodiment of the present invention is to provide a novel organic compound.

[0020] Note that the description of the above problems does not preclude the existence of other problems. Note that one embodiment of the present invention does not necessarily have to solve all of these problems. Problems other than those described above are self-evident from the description of the specification, etc., and problems other than those described above can be extracted from the description of the specification, etc. [Means for solving the problem]

[0021] One embodiment of the present invention is an organic compound represented by the following general formula (G1-1).

[0022] [ka]

[0023] However, in the above general formula (G1-1), R 1 ~R 10each independently represents one of hydrogen, an alkyl group having 3 to 10 carbon atoms, or a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms; Ar 1 and Ar 2 Each of Ar independently represents a substituted aromatic hydrocarbon group having 6 to 13 carbon atoms. 1 and Ar 2 has at least one cycloalkyl group having 3 to 12 carbon atoms and one cycloalkyl group having a crosslinked structure and having 7 to 10 carbon atoms as a substituent.

[0024] Alternatively, another aspect of the present invention is the above-mentioned structure, 1 and Ar 2 is an organic compound in which the phenyl group has a substituent.

[0025] Another embodiment of the present invention is an organic compound represented by the following general formula (G1-2).

[0026] [ka]

[0027] However, in the above general formula (G1-2), R 1 ~R 10 each independently represents one of hydrogen, an alkyl group having 3 to 10 carbon atoms, or a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms; Ar 1 and Ar 2 Each of Ar independently represents an aromatic hydrocarbon group having 6 to 13 carbon atoms and having three or more substituents. 1 and Ar 2 The substituents of the group represented by the formula (1) are a plurality of groups selected from an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, and a cycloalkyl group having 7 to 10 carbon atoms and having a crosslinked structure.

[0028] Alternatively, another aspect of the present invention is the above-mentioned structure, 1 and Ar 2is an organic compound in which each of the groups has 3 to 5 substituents.

[0029] Alternatively, another aspect of the present invention is the above-mentioned structure, 1 and Ar 2 is an organic compound in which the phenyl group has a substituent.

[0030] Alternatively, another aspect of the present invention is the above-mentioned structure, 1 and Ar 2 The substituents each of 1 and Ar 2 It is an organic compound in which the carbon atom is bonded to both the ortho and para positions of the carbon atom.

[0031] Alternatively, another aspect of the present invention is the above-mentioned structure, 1 and Ar 2 are organic compounds each having three substituents.

[0032] Alternatively, another aspect of the present invention is the above-mentioned structure, 1 and Ar 2 are organic compounds in which each of the substituents has a cyclohexyl group.

[0033] Another embodiment of the present invention is an organic compound represented by the following general formula (G2).

[0034] [ka]

[0035] However, in the above general formula (G2), R 1 ~R 10 and R 21 ~R 24 each independently represents one of hydrogen, an alkyl group having 3 to 10 carbon atoms, or a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms; X 1 ~X 6each independently represents any one of an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, and a cycloalkyl group having 7 to 10 carbon atoms and having a crosslinked structure.

[0036] Alternatively, another aspect of the present invention is the above-mentioned structure, wherein the R 21 ~R 24 is an organic compound in which is hydrogen.

[0037] Alternatively, another aspect of the present invention is the above-mentioned structure, wherein the X 1 ~X 6 is an organic compound in which the alkyl group is a cycloalkyl group having 3 to 12 carbon atoms.

[0038] Alternatively, another aspect of the present invention is the above-mentioned structure, wherein the X 1 ~X 6 is an organic compound in which the cyclohexyl group is

[0039] Alternatively, another aspect of the present invention is the above-mentioned structure, wherein the R 1 ~R 10 is an organic compound in which is hydrogen.

[0040] Another embodiment of the present invention is a light-emitting material containing any of the above organic compounds.

[0041] Another embodiment of the present invention is a material for a light-emitting device, including any of the organic compounds described above.

[0042] Another embodiment of the present invention is a light-emitting material for a light-emitting element, which includes any of the above organic compounds and is configured to receive excitation energy from a material having a function of converting triplet excitation energy into light emission in an light-emitting layer and convert the energy into light emission from a singlet excited state.

[0043] Another embodiment of the present invention is a light-emitting device including any of the above organic compounds.

[0044] Another embodiment of the present invention is a light-emitting device in which a light-emitting layer includes a material having a function of converting triplet excitation energy into light emission and any of the organic compounds described above.

[0045] Another embodiment of the present invention is an electronic device including any of the above light-emitting devices and a sensor, an operation button, a speaker, or a microphone.

[0046] Another embodiment of the present invention is a light-emitting device including the above light-emitting device and a transistor or a substrate.

[0047] Another embodiment of the present invention is a lighting device including the above-described light-emitting device and a housing.

[0048] One embodiment of the present invention includes not only a light-emitting device having a light-emitting device but also an electronic device having a light-emitting device. Therefore, the term "light-emitting device" in this specification refers to an image display device or a light source (including a lighting device). The light-emitting (display) device may also include a display module in which a connector, such as a flexible printed circuit (FPC) or a tape carrier package (TCP), is attached to a light-emitting device, a display module in which a printed wiring board is provided at the end of a TCP, or a display module in which an integrated circuit (IC) is directly mounted on a light-emitting device using a chip-on-glass (COG) method. [Effects of the Invention]

[0049] According to the present invention, an organic compound with which a light-emitting device having high emission efficiency can be obtained can be provided. Alternatively, in one embodiment of the present invention, an organic compound with which a highly reliable light-emitting device can be obtained can be provided. Alternatively, in one embodiment of the present invention, an organic compound with which a light-emitting device having reduced power consumption can be provided. Furthermore, in one embodiment of the present invention, a light-emitting device having high color purity can be provided. Furthermore, in one embodiment of the present invention, a light-emitting device having high color purity and high emission efficiency can be provided.

[0050] 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 high reliability can be provided. Alternatively, according to one embodiment of the present invention, a light-emitting device with reduced power consumption can be provided. Alternatively, according to one embodiment of the present invention, a novel light-emitting device can be provided. Alternatively, according to one embodiment of the present invention, a novel light-emitting device can be provided. Alternatively, according to one embodiment of the present invention, a novel display device can be provided. Alternatively, a novel organic compound can be provided.

[0051] Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. Note that effects other than these are self-evident from the description in the specification, drawings, claims, etc., and it is possible to extract other effects from the description in the specification, drawings, claims, etc. [Brief explanation of the drawings]

[0052] [Figure 1] 1A and 1B are schematic cross-sectional views of a light-emitting layer of a light-emitting device according to one embodiment of the present invention, and FIG. 1C is a diagram illustrating the correlation between energy levels. [Figure 2] 2A and 2B are conceptual diagrams of a conventional guest material and a guest material used in a light-emitting device according to one embodiment of the present invention. [Figure 3] 3A and 3B show the structural formula and ball-and-stick diagram of a guest material used in a light-emitting device according to one embodiment of the present invention. [Figure 4] FIG. 4A is a schematic cross-sectional view of a light-emitting layer of a light-emitting device according to one embodiment of the present invention, and FIGS. 4B to 4D are diagrams illustrating the correlation of energy levels of a light-emitting device according to one embodiment of the present invention. [Figure 5] FIG. 5A is a schematic cross-sectional view of a light-emitting layer of a light-emitting device according to one embodiment of the present invention, and FIGS. 5B and 5C are diagrams illustrating the correlation between energy levels. [Figure 6]FIG. 6A is a schematic cross-sectional view of a light-emitting layer of a light-emitting device according to one embodiment of the present invention, and FIGS. 6B and 6C are diagrams illustrating the correlation between energy levels. [Figure 7] FIG. 7 is a schematic cross-sectional view of a light-emitting device according to one embodiment of the present invention. [Figure 8] FIG. 8A is a top view illustrating a display device of one embodiment of the present invention, and FIG. 8B is a cross-sectional schematic view. [Figure 9] 9A and 9B are cross-sectional schematic views illustrating a display device according to one embodiment of the present invention. [Figure 10] 10A and 10B are cross-sectional schematic views illustrating a display device according to one embodiment of the present invention. [Figure 11] 11A to 11D are perspective views illustrating a display module of one embodiment of the present invention. [Figure 12] 12A to 12C illustrate electronic devices according to one embodiment of the present invention. [Figure 13] 13A and 13B are perspective views illustrating a display device according to one embodiment of the present invention. [Figure 14] FIG. 14 illustrates a lighting device according to one embodiment of the present invention. [Figure 15] Figures 15A and 15B are 1H-NMR charts of ch3P2Qd. [Figure 16] FIG. 16 shows the absorption and emission spectra of ch3P2Qd in solution. [Figure 17] FIG. 17 shows the luminance-current density characteristics of the light-emitting device 1 and the comparative light-emitting device 1. [Figure 18] FIG. 18 shows the current efficiency-luminance characteristics of light-emitting device 1, comparative light-emitting device 1, and comparative light-emitting device 2. [Figure 19] FIG. 19 shows the luminance-voltage characteristics of light-emitting device 1, comparative light-emitting device 1, and comparative light-emitting device 2. [Figure 20] FIG. 20 shows the current-voltage characteristics of light-emitting device 1, comparative light-emitting device 1, and comparative light-emitting device 2. [Figure 21]FIG. 21 shows the power efficiency-luminance characteristics of light-emitting device 1, comparative light-emitting device 1, and comparative light-emitting device 2. [Figure 22] FIG. 22 shows the external quantum efficiency-luminance characteristics of light-emitting device 1, comparative light-emitting device 1, and comparative light-emitting device 2. [Figure 23] FIG. 23 shows the emission spectra of light-emitting device 1, comparative light-emitting device 1, and comparative light-emitting device 2. [Figure 24] Figures 24A and 24B are 1H-NMR charts of 3,10tBu-ch3P2Qd. [Figure 25] FIG. 25 shows the absorption and emission spectra of 3,10tBu-ch3P2Qd in solution. [Figure 26] FIG. 26 shows the luminance-current density characteristics of the light-emitting device 2, the comparative light-emitting device 3, and the comparative light-emitting device 4. [Figure 27] FIG. 27 shows the current efficiency-luminance characteristics of the light-emitting device 2, the comparative light-emitting device 3, and the comparative light-emitting device 4. [Figure 28] FIG. 28 shows the luminance-voltage characteristics of the light-emitting device 2, the comparative light-emitting device 3, and the comparative light-emitting device 4. [Figure 29] FIG. 29 shows the current-voltage characteristics of the light-emitting device 2, the comparative light-emitting device 3, and the comparative light-emitting device 4. [Figure 30] FIG. 30 shows the power efficiency-luminance characteristics of the light-emitting device 2, the comparative light-emitting device 3, and the comparative light-emitting device 4. [Figure 31] FIG. 31 shows the external quantum efficiency-luminance characteristics of the light-emitting device 2, the comparative light-emitting device 3, and the comparative light-emitting device 4. [Figure 32] FIG. 32 shows the emission spectra of light-emitting device 2, comparative light-emitting device 3, and comparative light-emitting device 4. [Figure 33] FIG. 33 is a graph showing the effect of dopant concentration on luminous efficiency. [Figure 34] FIG. 34 shows the luminance-current density characteristics of the light-emitting device 3 and the comparative light-emitting device 5. [Figure 35]FIG. 35 shows the current efficiency-luminance characteristics of the light-emitting device 3 and the comparative light-emitting device 5. [Figure 36] FIG. 36 shows the luminance-voltage characteristics of the light-emitting device 3 and the comparative light-emitting device 5. [Figure 37] FIG. 37 shows the current-voltage characteristics of the light-emitting device 3 and the comparative light-emitting device 5. [Figure 38] FIG. 38 shows the power efficiency-luminance characteristics of the light-emitting device 3 and the comparative light-emitting device 5. [Figure 39] FIG. 39 shows the external quantum efficiency-luminance characteristics of the light-emitting device 3 and the comparative light-emitting device 5. [Figure 40] FIG. 40 shows the emission spectra of the light-emitting device 3 and the comparative light-emitting device 5. DETAILED DESCRIPTION OF THE INVENTION

[0053] 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 various changes in form and details may 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.

[0054] In this specification and the like, the singlet excited state (S * ) is a singlet state with an excited energy. The S1 level is the lowest excited energy level of the singlet excited state (S1 state). The triplet excited state (T * ) refers to a triplet state having an excitation energy. The T1 level refers to the excitation energy level of the lowest triplet excited state (T1 state). In this specification, even when simply referring to a singlet excited state and a singlet excited energy level, it may refer to the S1 state and the S1 level. Even when simply referring to a triplet excited state and a triplet excited energy level, it may refer to the T1 state and the T1 level.

[0055] In addition, in this specification, a fluorescent material is a compound that emits light in the visible light region when relaxing from a singlet excited state to a ground state. A phosphorescent material is a compound that emits light in the visible light region at room temperature when relaxing from a triplet excited state to a ground state. In other words, a phosphorescent material is a compound that can convert triplet excited energy into visible light. In this specification, room temperature refers to a temperature in the range of 0°C to 40°C.

[0056] In this specification, the blue wavelength range is from 400 nm to less than 490 nm, and the blue emission has at least one emission spectrum peak in this wavelength range. The green wavelength range is from 490 nm to less than 580 nm, and the green emission has at least one emission spectrum peak in this wavelength range. The red wavelength range is from 580 nm to 680 nm, and the red emission has at least one emission spectrum peak in this wavelength range.

[0057] (Embodiment 1) In this embodiment, in a light-emitting device having an emission layer including a host material capable of converting triplet excitation energy into light emission and a guest material (a fluorescent material) capable of converting singlet excitation energy into light emission, an organic compound that can be used as a guest material capable of efficiently converting triplet excitation energy of the host material into light emission will be described.

[0058] When excitation energy is transferred from a host material capable of converting triplet excitation energy into luminescence to a guest material capable of converting singlet excitation energy into luminescence, if the triplet excitation energy transfer occurs from the triplet excitation energy level of the host material to the triplet excitation energy level of the guest material, non-radiative decay of the triplet excitation energy of the guest material will be dominant, resulting in the generation of energy that does not contribute to luminescence. Because this undesired energy transfer is based on the Dexter mechanism, measures to suppress this are sometimes taken to reduce the doping concentration of the guest material. However, in this case, not only the energy transfer based on the Dexter mechanism but also the energy transfer based on the Förster mechanism is simultaneously suppressed, which can adversely affect efficiency and lifetime.

[0059] In general, it is known that the Dexter mechanism predominates when the distance between the host and guest materials is 1 nm or less, and the Förster mechanism predominates when the distance is 1 nm or more but 10 nm or less. Note that the distance in this case essentially refers to the distance between the host material and the framework (luminophore) that is responsible for the emission of the guest material.

[0060] The above-mentioned measure of reducing the doping concentration of the guest material suppresses energy transfer via both the Dexter mechanism and the Förster mechanism.

[0061] That is, in a light-emitting device having a host material capable of converting triplet excitation energy into luminescence and a guest material (fluorescent material) capable of converting singlet excitation energy into luminescence in the emissive layer, maintaining an appropriate distance between the host material and the luminophores of the guest material can block the energy transfer from the triplet excitation energy level of the host material to the triplet excitation energy level of the guest material based on the Dexter mechanism and the subsequent energy deactivation pathway by non-radiative deactivation, thereby achieving a light-emitting device with excellent luminous efficiency and lifetime, primarily based on energy transfer based on the Förster mechanism. In this case, the distance between the host material and the luminophores of the guest material is preferably 1 nm or more and 10 nm or less. Therefore, it is preferable that the guest material have a bulky substituent that functions to maintain an appropriate distance between the luminophores and the host material.

[0062] Therefore, one aspect of the present invention provides an organic compound having a protecting group that enables such a light-emitting device. The protecting group means a substituent that has the function of maintaining an appropriate distance between the host material and the luminophore.

[0063] That is, an organic compound according to one embodiment of the present invention is an organic compound represented by the following general formula (G1-1).

[0064] [ka]

[0065] However, in the above general formula (G1-1), R 1 ~R 10 each independently represents one of hydrogen, an alkyl group having 3 to 10 carbon atoms, and a cycloalkyl group having 3 to 10 carbon atoms; Ar 1 and Ar 2 Each of Ar independently represents a substituted aromatic hydrocarbon group having 6 to 13 carbon atoms. 1 and Ar 2 has at least one cycloalkyl group having 3 to 12 carbon atoms or one cycloalkyl group having 7 to 10 carbon atoms and having a crosslinked structure as a substituent.

[0066] The organic compound represented by the general formula (G1-1) has a quinacridone skeleton as a luminophore, and Ar 1 and Ar 2 The substituent bonded to functions as a protecting group. When the protecting group is a cycloalkyl group having 3 to 12 carbon atoms or a cycloalkyl group having 7 to 10 carbon atoms and a bridged structure, the organic compound represented by General Formula (G1-1) can maintain an appropriate distance from the host material, and energy transfer based on the Dexter mechanism can be effectively suppressed. For this reason, when the organic compound represented by General Formula (G1-1) is used as a guest material in a light-emitting device having an emitting layer containing a host material capable of converting triplet excitation energy into light emission and a guest material capable of converting singlet excitation energy into light emission, the organic compound can efficiently receive energy from the host material through energy transfer based on the Förster mechanism while suppressing energy transfer based on the Dexter mechanism.

[0067] Furthermore, the organic compound represented by the general formula (G1-1) has a quinacridone skeleton as a luminophore and has a high fluorescence quantum yield, making it possible to realize a light-emitting device that exhibits very good luminous efficiency.

[0068] The organic compound represented by the general formula (G1-1) is Ar 1 and Ar 2 is preferably a phenyl group, since synthesis is easy and sublimation is high.

[0069] Another embodiment of the present invention is an organic compound represented by the following general formula (G1-2).

[0070] [ka]

[0071] However, in the above general formula (G1-2), R 1 ~R 10each independently represents one of hydrogen, an alkyl group having 3 to 10 carbon atoms, and a cycloalkyl group having 3 to 10 carbon atoms; Ar 1 and Ar 2 Each of Ar independently represents an aromatic hydrocarbon group having 6 to 13 carbon atoms and having three or more substituents. 1 and Ar 2 The substituents of the group represented by the formula (1) are a plurality of groups selected from an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, and a cycloalkyl group having 7 to 10 carbon atoms and having a crosslinked structure.

[0072] The organic compound represented by the general formula (G1-2) has a quinacridone skeleton as a luminophore, and Ar 1 and Ar 2 The substituents on Ar function as protecting groups. 1 and Ar 2 By bonding three or more, preferably three to five, of these protecting groups to each of the organic compounds represented by general formula (G1-2), the organic compound represented by general formula (G1-2) can maintain an appropriate distance from the host material and effectively suppress energy transfer based on the Förster mechanism. For this reason, when the organic compound represented by general formula (G1-2) is used as a guest material in a light-emitting device having an emitting layer containing a host material capable of converting triplet excitation energy into luminescence and a guest material capable of converting singlet excitation energy into luminescence, the organic compound can efficiently receive energy from the host material through energy transfer based on the Förster mechanism.

[0073] The organic compound represented by the general formula (G1-2) is Ar 1 and Ar 2 is preferably a phenyl group, since synthesis is easy and sublimation is high.

[0074] In addition, the Ar 1 and Ar 2 The substituents each of Ar 1 and Ar 2The bonding at both the ortho and para positions of Ar results in good sublimation properties. 1 and Ar 2 The number of substituents each of the groups has is preferably three, since synthesis is simple, sublimation is more favorable, and energy transfer by the Dexter mechanism can be effectively suppressed.

[0075] Also Ar 1 and Ar 2 The substituents that each of the groups has are preferably cycloalkyl groups, preferably cyclohexyl groups, since this more effectively suppresses energy transfer via the Dexter mechanism.

[0076] As described above, the organic compound according to one embodiment of the present invention is Ar 1 and Ar 2 is preferably a phenyl group, and the protecting groups bonded to the phenyl group are preferably bonded to both the ortho- and para-positions. That is, the organic compound of one embodiment of the present invention is preferably an organic compound represented by the following general formula (G2):

[0077] [ka]

[0078] However, in the above general formula (G2), R 1 ~R 10 and R 21 ~R 24 each independently represents one of hydrogen, an alkyl group having 3 to 10 carbon atoms, and a cycloalkyl group having 3 to 10 carbon atoms; X 1 ~X 6 each independently represents any one of an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, and a cycloalkyl group having 7 to 10 carbon atoms and having a crosslinked structure.

[0079] In the organic compound represented by the general formula (G2), the quinacridone skeleton is a luminophore, and X 1 ~X 6functions as a protecting group. This allows the organic compound represented by the general formula (G2) to maintain an appropriate distance from the host material, thereby effectively suppressing energy transfer based on the Dexter mechanism. For this reason, when the organic compound represented by the general formula (G2) is used as a guest material in a light-emitting device having an emitting layer containing a host material capable of converting triplet excitation energy into light emission and a guest material capable of converting singlet excitation energy into light emission, the organic compound can efficiently receive energy from the host material through energy transfer based on the Förster mechanism.

[0080] In the above general formula (G2), R 21 ~R 24 It is preferable that X is hydrogen because it is easy to synthesize. 1 ~X 6 is preferably any cycloalkyl group having 3 to 12 carbon atoms for ease of synthesis, and more preferably a cyclohexyl group.

[0081] In addition, in the above general formulae (G1-1), (G1-2) and (G2), R 1 ~R 10 is preferably hydrogen because of ease of synthesis.

[0082] The organic compound of the present invention having such a structure can appropriately maintain the distance between the luminophore contained in the organic compound and the host material, thereby effectively suppressing undesired energy transfer, and by using the organic compound of the present invention, a light-emitting element having good luminous efficiency and a long lifetime can be provided.

[0083] Furthermore, the organic compounds represented by the above general formulas (G1-1), (G1-2) and (G2) also have high fluorescence quantum yields, making it possible to realize light-emitting devices that exhibit very good luminous efficiency.

[0084] In the present embodiment, specific examples of the alkyl group having 3 or more and 10 or less carbon atoms include an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a sec-butyl group, a neopentyl group, an n-hexyl group, an n-octyl group, and an n-decyl group, and examples of the cycloalkyl group having 3 or more and 10 or less carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononanyl group, and a cyclodecyl group.

[0085] Similarly, in this embodiment, examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a sec-butyl group, a neopentyl group, an n-hexyl group, an n-octyl group, and an n-decyl group; examples of the cycloalkyl group having 3 to 12 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononanyl group, a cyclodecyl group, and a cyclododecyl group; and examples of the cycloalkyl group having 7 to 10 carbon atoms and having a crosslinked structure include an adamantyl group, a norbornanyl group, and a tetrahydrodicyclopentadienyl group.

[0086] Specific examples of such organic compounds include organic compounds represented by the following structural formulas (100) to (140).

[0087] [ka]

[0088] [ka]

[0089] [ka]

[0090] [ka]

[0091] [ka]

[0092] [ka]

[0093] [ka]

[0094] [ka]

[0095] [ka]

[0096] Next, an example of a method for synthesizing the above organic compounds will be described using organic compounds represented by general formulas (G1-1) and (G2) as examples.

[0097] <Method for synthesizing organic compounds represented by general formula (G1-1)> The organic compound of one embodiment of the present invention represented by the following general formula (G1-1) can be synthesized by utilizing any organic reaction, but two methods will be shown below as examples.

[0098] [ka]

[0099] In the general formula (G1-1), R 1 ~R 10each independently represents one of hydrogen, an alkyl group having 3 to 10 carbon atoms, and a cycloalkyl group having 3 to 10 carbon atoms; Ar 1 and Ar 2 Each of Ar independently represents a substituted aromatic hydrocarbon group having 6 to 13 carbon atoms. 1 and Ar 2 has at least one cycloalkyl group having 3 to 12 carbon atoms or one cycloalkyl group having 7 to 10 carbon atoms and having a crosslinked structure as a substituent.

[0100] The first method is a synthesis method consisting of the following synthesis schemes (S-1) to (S-6). The first step is a process for obtaining an amine compound (compound 3) by a dehydration condensation reaction between an aniline compound (compound 1) and a 1,4-cyclohexadiene-2,5-dicarboxylic acid compound (compound 2). This process is shown in scheme (S-1).

[0101] [ka]

[0102] Next, a condensation reaction between an amine compound (compound 3) and an aniline derivative (compound 4) can be performed to obtain a 1,4-cyclohexadiene compound (compound 5). The process for obtaining compound 5 is shown in Scheme (S-2).

[0103] [ka]

[0104] Furthermore, when introducing an amino group of the same structure into a 1,4-cyclohexadiene compound (compound 5), it is preferable to add two equivalents of an aniline compound (compound 1) in the synthetic scheme (S-1) and carry out the same reaction. In this case, a single target product can be obtained even if the carbonyl group of compound 2 does not have reaction selectivity.

[0105] Next, the 1,4-cyclohexadiene compound (compound 5) is oxidized in air to obtain a terephthalic acid compound (compound 6). The process for obtaining compound 6 is shown in Scheme (S-3).

[0106] [ka]

[0107] Subsequently, the terephthalic acid compound (Compound 6) is subjected to intramolecular cyclization using an acid to obtain a quinacridone compound (Compound 7). The process for obtaining Compound 7 is shown in Scheme (S-4).

[0108] [ka]

[0109] Then, the quinacridone compound (Compound 7) is coupled with the aryl halide compound (Compound 8) to obtain the quinacridone compound (Compound 9). The process for obtaining Compound 9 is shown in Scheme (S-5).

[0110] [ka]

[0111] Then, the quinacridone compound (compound 9) and the aryl halide compound (compound 10) are coupled to obtain the organic compound represented by the general formula (G1-1). This process is shown in Scheme (S-6).

[0112] [ka]

[0113] Furthermore, when Ar1 and Ar2 have the same structure in general formula (G1-1), two identical aryl halide compounds (compound 8) can be coupled in scheme (S-5), so it is preferable to add two equivalents of the aryl halide compound (compound 8) and perform the same reaction. In this case, a single target product can be obtained even if the amino group of compound 7 does not have reaction selectivity.

[0114] The second method consists of the following synthetic schemes (S-1) to (S-3) and (S-7) to (S-9). The explanations for (S-1) to (S-3) are as above.

[0115] The diamine compound (Compound 11) can be obtained by coupling the terephthalic acid compound (Compound 6) obtained by Scheme (S-3) with an aryl halide compound (Compound 8). The process for obtaining Compound 11 is shown in Scheme (S-7).

[0116] [ka]

[0117] Next, the diamine compound (Compound 11) and the aryl halide compound (Compound 10) are coupled to obtain the diamine compound (Compound 12). The process for obtaining Compound 12 is shown in Scheme (S-8).

[0118] [ka]

[0119] Furthermore, when Ar1 and Ar2 in the diamine compound (compound 12) have the same structure, two molecules of the same aryl halide compound can be coupled to the terephthalic acid compound (compound 6) in a single step, so it is preferable to perform the same reaction by adding two equivalents of the aryl halide compound (compound 8). In this case, a single target product can be obtained even if the amino group of compound 6 does not have reaction selectivity.

[0120] Finally, the diamine compound (Compound 12) is subjected to ring condensation using an acid to obtain the organic compound represented by the general formula (G1-1). This process is shown in Scheme (S-9).

[0121] [ka]

[0122] In scheme (S-9), by using a diamine compound (compound 12) having a symmetric structure, it is possible to synthesize an organic compound represented by the above general formula (G1-1).

[0123] In the synthesis schemes (S-1) to (S-4) and (S-7) to (S-9), Al 1 represents an alkyl group having 1 to 4 carbon atoms.

[0124] In the synthesis schemes (S-5) to (S-8), Y 1 and Y 2 represents a chlorine atom, a bromine atom, an iodine atom, or a triflate group.

[0125] In the synthesis scheme (S-3), oxidation can be carried out with oxygen in the air, but it is more preferable to use iodine or the like as an oxidizing agent.

[0126] In the synthetic schemes (S-5) to (S-8), the Ullmann reaction is preferred because it can proceed at high temperatures and can produce the target compound in relatively high yield. Reagents that can be used in this reaction include copper or copper compounds, and inorganic bases such as potassium carbonate and sodium hydride. Solvents that can be used in this reaction include 2,2,6,6-tetramethyl-3,5-heptanedione, 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)pyrimidinone (DMPU), toluene, xylene, benzene, and diphenyl ether. In the Ullmann reaction, a reaction temperature of 100°C or higher results in a shorter time and higher yield, so it is preferable to use 2,2,6,6-tetramethyl-3,5-heptanedione, DMPU, xylene, or diphenyl ether, which have high boiling points. Furthermore, a reaction temperature of 150°C or higher is even more preferable, so DMPU and diphenyl ether are more preferred. Reagents that can be used in this reaction are not limited to those listed above.

[0127] In the synthesis schemes (S-5) to (S-8), the Buchwald-Hartwig reaction can be carried out using a palladium catalyst. In this reaction, palladium compounds such as bis(dibenzylideneacetone)palladium(0), palladium(II) acetate, [1,1-bis(diphenylphosphino)ferrocene]palladium(II) dichloride, tetrakis(triphenylphosphine)palladium(0), and allylpalladium(II) chloride (dimer) can be used. Ligands such as tri(tert-butyl)phosphine, tri(n-hexyl)phosphine, tricyclohexylphosphine, di(1-adamantyl)-n-butylphosphine, 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl, tri(orthotolyl)phosphine, and (S)-(6,6'-dimethoxybiphenyl-2,2'-diyl)bis(diisopropylphosphine) (abbreviated as cBRIDP (registered trademark)) can be used in this reaction. Organic bases such as sodium tert-butoxide and inorganic bases such as potassium carbonate, cesium carbonate, and sodium carbonate can be used in this reaction. Solvents such as toluene, xylene, benzene, tetrahydrofuran, and dioxane can be used in this reaction. Reagents that can be used in this reaction are not limited to those listed above.

[0128] Furthermore, the method for synthesizing the organic compound represented by general formula (G1-1) of the present invention is not limited to the synthesis schemes (S-1) to (S-9).

[0129] In general formula (G1-1), R 1 ~R 10 each independently represents one of hydrogen, an alkyl group having from 3 to 10 carbon atoms, and a substituted or unsubstituted cycloalkyl group having from 3 to 10 carbon atoms. Specific examples include hydrogen, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a cyclopropyl group, an n-hexyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononanyl group, and a cyclodecyl group.

[0130] In general formula (G1-1), Ar 1 and Ar 2 Each of Ar independently represents a substituted aromatic hydrocarbon group having 6 to 13 carbon atoms. 1 and Ar 2Each of these has at least one cycloalkyl group having 3 to 12 carbon atoms or one cycloalkyl group having 7 to 10 carbon atoms and a crosslinked structure as a substituent. Specific examples include a 2-cyclopropylphenyl group, a 2-cyclobutylphenyl group, a 2-cyclopentylphenyl group, a 2-cyclohexylphenyl group, a 2-cycloheptylphenyl group, a 2-cyclooctylphenyl group, a 2-adamantylphenyl group, a 2-norbornanylphenyl group, a 2-tetrahydrodicyclopentadienylphenyl group, a 3-cyclopropylphenyl group, a 3-cyclobutylphenyl group, a 3-cyclopentylphenyl group, a 3-cyclohexylphenyl group, a 3-cycloheptylphenyl group, a 3 ... octylphenyl group, 3-adamantylphenyl group, 3-norbornanylphenyl group, 3-tetrahydrodicyclopentadienylphenyl group, 4-cyclopropylphenyl group, 4-cyclobutylphenyl group, 4-cyclopentylphenyl group, 4-cyclohexylphenyl group, 4-cycloheptylphenyl group, 4-cyclooctylphenyl group, 4-adamantylphenyl group, 4-norbornanylphenyl group, 4-tetrahydrodicyclopentadienylphenyl group, 1,3-dicyclopropylphenyl group, 1,3-dicyclopentylphenyl group, cyclobutylphenyl group, 1,3-dicyclopentylphenyl group, 1,3-dicyclohexylphenyl group, 1,3-dicycloheptylphenyl group, 1,3-dicyclooctylphenyl group, 1,3-diadamantylphenyl group, 1,3-dinorbornanylphenyl group, 1,3-ditetrahydrodicyclopentadienylphenyl group, 1,5-dicyclopropylphenyl group, 1,5-dicyclobutylphenyl group, 1,5-dicyclopentylphenyl group, 1,5-dicyclohexylphenyl group, 1,5-dicycloheptylphenyl group phenyl group, 1,5-dicyclooctylphenyl group, 1,5-diadamantylphenyl group, 1,5-dinorbornanylphenyl group, 1,5-ditetrahydrodicyclopentadienylphenyl group, 3,4-dicyclopropylphenyl group, 3,4-dicyclobutylphenyl group, 3,4-dicyclopentylphenyl group, 3,4-dicyclohexylphenyl group, 3,4-dicycloheptylphenyl group, 3,4-dicyclooctylphenyl group, 3,4-diadamantylphenyl group, 3,4-dinorbornanylphenyl group, 3,4-ditetrahydrodicyclopentadienylphenyl group, 4-tricyclopentylphenyl group, 2,3,4-tricyclohexylphenyl group, 2,3,4-tricycloheptylphenyl group, 2,3,4-tricyclooctylphenyl group, 2,3,4-triadamantylphenyl group, 2,3,4-trinorbornanylphenyl group, 2,3,4-tritetrahydrodicyclopentadienylphenyl group, 3,4,5-tricyclopropylphenyl group, 3,4,5-tricyclobutylphenyl group, 3,4,5-tricyclopentylphenyl group Examples thereof include a 3,4,5-tricyclohexylphenyl group, a 3,4,5-tricycloheptylphenyl group, a 3,4,5-tricyclooctylphenyl group, a 3,4,5-triadamantylphenyl group, a 3,4,5-trinorbornanylphenyl group, a 3,4,5-tritetrahydrodicyclopentadienylphenyl group, a 3-cyclohexyl-2-naphthyl group, an 8-cyclohexyl-1-naphthyl group, a 9,9-dicyclohexyl-9H-fluoren-3-yl group, and a 9,9-dicyclohexyl-9H-fluoren-2-yl group.

[0131] Furthermore, the method for synthesizing the organic compound represented by general formula (G1-1) of the present invention is not limited to the synthesis schemes (S-1) to (S-9).

[0132] <Method for synthesizing organic compound represented by general formula (G2)> The organic compound of one embodiment of the present invention represented by the following general formula (G2) can be synthesized by utilizing any organic reaction. As an example, two methods are shown below.

[0133] [ka]

[0134] The first method consists of the following synthetic schemes (S-1) to (S-4), (S-10), and (S-11). The explanations for (S-1) to (S-4) are as above. Following synthetic scheme (S-4), a quinacridone compound (compound 7) can be coupled with an aryl halide compound (compound 13) to obtain a quinacridone compound (compound 14). The process for obtaining compound 14 is shown in scheme (S-10). However, if two identical aryl halide compounds (compound 13) can be coupled in a single step and an amino group with the same structure is introduced, it is preferable to perform the same reaction by adding two equivalents of the aryl halide compound (compound 13). In this case, a single target product can be obtained even if the amino group of compound 7 does not have reaction selectivity.

[0135] [ka]

[0136] Next, the quinacridone compound (Compound 14) and the aryl halide compound (Compound 15) are coupled to obtain the organic compound represented by the general formula (G2). This process is shown in Scheme (S-11).

[0137] [ka]

[0138] Furthermore, when the substituents on the phenyl groups in compound (G2) are the same, two identical aryl halide compounds (compound 13) can be coupled in scheme (S-10), so it is preferable to add two equivalents of the aryl halide compound (compound 13) and perform the same reaction. In this case, a single target product can be obtained even if the amino group of compound 7 does not have reaction selectivity.

[0139] The second method consists of the following synthesis schemes (S-1) to (S-3) and (S-12) to (S-14). The explanation of (S-1) to (S-3) is as above. Following (S-3), a diamine compound (compound 16) can be obtained by coupling a terephthalic acid compound (compound 6) with an aryl halide compound (compound 13). The process for obtaining compound 16 is shown in scheme (S-12).

[0140] [ka]

[0141] Next, the diamine compound (Compound 16) can be coupled with the aryl halide (Compound 15) to obtain the diamine compound (Compound 17). The process for obtaining Compound 17 is shown in Scheme (S-13).

[0142] [ka]

[0143] Furthermore, when the substituents on the phenyl groups of the terephthalic acid compound (compound 17) are the same, two molecules of the same aryl halide compound can be coupled in one step. To introduce amino groups of the same structure, it is preferable to add two equivalents of the aryl halide compound (compound 13) and perform the same reaction. In this case, a single target product can be obtained even if the amino group of compound 6 does not have reaction selectivity.

[0144] Finally, the terephthalic acid compound (compound 17) can be condensed with an acid to obtain the organic compound represented by the general formula (G2). This process is shown in Scheme (S-14).

[0145] [ka]

[0146] In the synthesis schemes (S-1) to (S-4) and (S-12) to (S-14), Al 1 represents an alkyl group having 1 to 4 carbon atoms.

[0147] In the synthesis schemes (S-10) to (S-13), Y 1 and Y 2 represents a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or a triflate group.

[0148] In the synthesis schemes (S-10) to (S-13), the Ullmann reaction is preferred because it can proceed at high temperatures and can produce the target compound in relatively high yield. Reagents that can be used in this reaction include copper or copper compounds, and bases include inorganic bases such as potassium carbonate and sodium hydride. Solvents that can be used in this reaction include 2,2,6,6-tetramethyl-3,5-heptanedione, 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)pyrimidinone (DMPU), toluene, xylene, benzene, and diphenyl ether. In the Ullmann reaction, a reaction temperature of 100°C or higher results in a shorter time and higher yield, so it is preferable to use 2,2,6,6-tetramethyl-3,5-heptanedione, DMPU, xylene, or diphenyl ether, which have high boiling points. Furthermore, a reaction temperature of 150°C or higher is even more preferable, so DMPU and diphenyl ether are more preferred. Reagents that can be used in this reaction are not limited to the above-mentioned reagents.

[0149] In the synthesis schemes (S-10) to (S-13), the Buchwald-Hartwig reaction using a palladium catalyst can be carried out. In this reaction, palladium compounds such as bis(dibenzylideneacetone)palladium(0), palladium(II) acetate, [1,1-bis(diphenylphosphino)ferrocene]palladium(II) dichloride, tetrakis(triphenylphosphine)palladium(0), and allylpalladium(II) chloride (dimer) can be used. The reaction can be carried out using a ligand such as tri(tert-butyl)phosphine, tri(n-hexyl)phosphine, tricyclohexylphosphine, di(1-adamantyl)-n-butylphosphine, 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl, tri(orthotolyl)phosphine, or (S)-(6,6'-dimethoxybiphenyl-2,2'-diyl)bis(diisopropylphosphine) (abbreviated as cBRIDP (registered trademark)). In this reaction, an organic base such as sodium tert-butoxide or an inorganic base such as potassium carbonate, cesium carbonate, or sodium carbonate can be used. In this reaction, a solvent such as toluene, xylene, benzene, tetrahydrofuran, or dioxane can be used. The reagents that can be used in this reaction are not limited to those listed above.

[0150] Furthermore, the method for synthesizing the organic compound represented by general formula (G2) of the present invention is not limited to the synthesis schemes (S-1) to (S-4) and (S-10) to (S-14).

[0151] In the above general formula (G2), R 1 ~R 10 and R 21 ~R 24each independently represents one of hydrogen, an alkyl group having from 3 to 10 carbon atoms, and a substituted or unsubstituted cycloalkyl group having from 3 to 10 carbon atoms. Specific examples include hydrogen, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, an n-hexyl group, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononanyl group, and a cyclodecyl group.

[0152] In the above general formula (G2), X 1 ~X 3 and X 4 ~X 6 each independently represents any one of an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, and a cycloalkyl group having a crosslinked structure and having 7 to 10 carbon atoms. Specific examples include an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, an n-hexyl group, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononanyl group, a cyclodecyl group, an adamantyl group, a norbornanyl group, and a tetrahydrodicyclopentadienyl group.

[0153] The synthesis methods of the organic compounds represented by general formula (G1-1) and general formula (G2), which are one embodiment of the present invention, have been described above. However, the present invention is not limited thereto, and the compounds may be synthesized by other synthesis methods.

[0154] (Embodiment 2) A light-emitting device according to one embodiment of the present invention will be described below with reference to FIGS.

[0155] <Example of light-emitting device configuration> First, a structure of a light-emitting device of one embodiment of the present invention will be described below with reference to FIG.

[0156] FIG. 1A is a schematic cross-sectional view of a light-emitting device 150 according to one embodiment of the present invention.

[0157] The light-emitting device 150 has a pair of electrodes (electrode 101 and electrode 102) and an EL layer 100 provided between the pair of electrodes. The EL layer 100 has at least a light-emitting layer 130.

[0158] 1A includes functional layers such as a hole injection layer 111, a hole transport layer 112, an electron transport layer 118, and an electron injection layer 119 in addition to the light-emitting layer .

[0159] In the present embodiment, the electrode 101 of the pair of electrodes is described as an anode and the electrode 102 as a cathode, but the configuration of the light-emitting device 150 is not limited to this. That is, the electrode 101 may be the cathode and the electrode 102 may be the anode, and the layers between the electrodes may be stacked in the reverse order. That is, the stacking order from the anode side may be the hole injection layer 111, the hole transport layer 112, the light-emitting layer 130, the electron transport layer 118, and the electron injection layer 119.

[0160] 1A , the EL layer 100 may have at least one selected from the group consisting of a hole injection layer 111, a hole transport layer 112, an electron transport layer 118, and an electron injection layer 119. Alternatively, the EL layer 100 may have a functional layer, such as a layer that reduces the injection barrier for holes or electrons, a layer that improves the transportability of holes or electrons, a layer that inhibits the transportability of holes or electrons, or a layer that suppresses quenching caused by an electrode. Each functional layer may be a single layer, or may have a laminated structure of multiple layers.

[0161] <Light-emitting mechanism of light-emitting devices> Next, the light-emitting mechanism of the light-emitting layer 130 will be described below. The light-emitting device 150 according to one embodiment of the present invention is a light-emitting device having, in its light-emitting layer, a host material capable of converting triplet excitation energy into light emission and a guest material (a fluorescent material) capable of converting singlet excitation energy into light emission. By using a host material capable of converting triplet excitation energy into light emission, triplet excitons can be made to contribute to light emission, thereby improving the luminous efficiency of the light-emitting device. Furthermore, by using a stable fluorescent material as the guest material, a light-emitting device with a long lifetime can be realized.

[0162] One example of a material capable of converting triplet excitation energy into luminescence is a compound capable of emitting phosphorescence (hereinafter also referred to as a phosphorescent material). In this specification and the like, a phosphorescent material refers to a compound that exhibits phosphorescence but does not exhibit fluorescence at temperatures below room temperature. The phosphorescent material is preferably a compound containing a metal element with a large spin-orbit interaction, specifically a compound containing a transition metal element, and particularly a compound containing a platinum group element (ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), or platinum (Pt)). Among these, iridium is preferred because it can increase the transition probability involved in the direct transition between the singlet ground state and the triplet excited state of the phosphorescent material.

[0163] TADF materials are also examples of materials capable of converting triplet excitation energy into light emission. TADF materials have a small difference between the S1 and T1 levels and can convert triplet excitation energy to singlet excitation energy through reverse intersystem crossing. Therefore, using TADF materials makes it possible to efficiently generate a singlet excited state from a triplet excited state. Furthermore, exciplexes (also known as exciplexes), which form an excited state using two types of substances, also have an extremely small difference between the S1 and T1 levels and have the same functionality as TADF materials.

[0164] Although it is difficult to directly determine the T1 level, its index can be determined from the phosphorescence spectrum observed at low temperatures (e.g., 10 K). That is, a tangent line can be drawn at the base of the spectrum on the short wavelength side, and the energy of the wavelength of the extrapolated line can be regarded as the T1 level.

[0165] Similarly, the index of the S1 level can be determined from the fluorescence spectrum at room temperature or low temperature. That is, a tangent line is drawn at the short-wavelength tail of the fluorescence spectrum, and the energy at the wavelength of the extrapolated line can be regarded as the S1 level.

[0166] In order to function as a TADF material, it is preferable that the difference between the S1 level and the T1 level is 0.2 eV or less.

[0167] Furthermore, examples of materials capable of converting triplet excitation energy into luminescence include nanostructures of transition metal compounds having a perovskite structure. Nanostructures of metal halide perovskites are particularly preferred. Nanoparticles and nanorods are preferred examples of such nanostructures.

[0168] FIG. 1B is a cross-sectional schematic diagram illustrating a light-emitting layer 130 of a light-emitting device according to one embodiment of the present invention. In one embodiment of the present invention, the light-emitting layer 130 includes compounds 131 and 132. Compound 131 is a material capable of converting triplet excitation energy into luminescence, and compound 132 is a material capable of converting singlet excitation energy into luminescence, i.e., a fluorescent material. Because fluorescent materials are highly stable, a highly reliable light-emitting device can be obtained by using a fluorescent material as compound 132. Here, compound 131 functions as an energy donor, and compound 132 functions as an energy acceptor.

[0169] <Emitting layer configuration example 1> 1C is a diagram showing the correlation of energy levels in the light-emitting layer of a light-emitting device according to one embodiment of the present invention, in which a TADF material is used for Compound 131. The notations and symbols in FIG. 1C are as follows. ·Host(131): Compound 131 ·Guest(132): Compound 132 T C1 :T1 level of compound 131 ·S C1 : S1 level of compound 131 ·S G : S1 level of compound 132 T G :T1 level of compound 132

[0170] Here, we focus on the triplet excitation energy of compound 131 generated by current excitation. In this configuration example, compound 131 has TADF properties. Therefore, compound 131 can convert triplet excitation energy into singlet excitation energy by upconversion (Fig. 1C, Route A1). The singlet excitation energy possessed by compound 131 can be transferred to compound 132 (Fig. 1C, Route A2). At this time, S C1 ≧S G It is preferable that:

[0171] The triplet excitation energy generated in compound 131 is transferred to the S1 level of compound 132, which is a guest material, via the above-mentioned routes A1 and A2, causing compound 132 to emit light, thereby improving the luminous efficiency of the fluorescent light-emitting device.

[0172] Here, if compound 132 is a normal fluorescent material, a process (Route A3 in Figure 1C) in which the triplet excitation energy of compound 131 is converted to the triplet excitation energy of compound 132 may occur simultaneously in competition with Routes A1 and A2. Since the triplet excitation energy of compound 132, which is a fluorescent material, does not contribute to light emission, the occurrence of energy transfer via Route A3 reduces the luminous efficiency of the light-emitting device. (In fact, T C1 From T G The energy transfer to T of compound 132 (route A3) is not direct. G energy transfer to a triplet excited state higher than T GThere may be a route that leads to this, but this process is omitted in the figure. G The deactivation process is the same for all.)

[0173] Here, the Förster mechanism (dipole-dipole interaction) and the Dexter mechanism (electron exchange interaction) are known as intermolecular energy transfer mechanisms. When the energy acceptor, compound 132, is a fluorescent material, the Dexter mechanism is dominant in the energy transfer of route A3. Generally, the Dexter mechanism occurs significantly when the distance between the energy donor, compound 131, and the energy acceptor, compound 132, is 1 nm or less. Therefore, in order to suppress route A3, it is important to increase the distance between the host material and the guest material, i.e., the distance between the energy donor and the energy acceptor.

[0174] Therefore, as a method for increasing the distance between the energy acceptor (compound 132) and the energy donor (compound 131), since the light-emitting layer 130 is a mixed film of compound 132 and compound 131, a method of lowering the concentration of compound 132 in the mixed film may be adopted.

[0175] However, lowering the concentration of the energy acceptor in the mixed film suppresses not only the energy transfer from the energy donor to the energy acceptor based on the Dexter mechanism but also the energy transfer based on the Förster mechanism. As a result, problems such as reduced luminous efficiency and reliability of the light-emitting device arise, since route A2 is an energy transfer based on the Förster mechanism.

[0176] Generally, when the distance between the luminophore possessed by the energy acceptor and the energy donor is 1 nm or less, the Dexter mechanism predominates, while when the distance is 1 nm or more and 10 nm or less, the Förster mechanism predominates. Generally, when the distance between the energy acceptor and the energy donor is 10 nm or more, energy transfer is unlikely to occur. In other words, to suppress energy transfer via the Dexter mechanism and avoid suppression of energy transfer via the Förster mechanism, it is necessary to strictly maintain the distance between the energy acceptor and the energy donor between 1 nm or more and 10 nm or less. Therefore, the present inventors have discovered that the above-mentioned decrease in luminescence efficiency can be suppressed by using a fluorescent material as the energy acceptor that has a protecting group to increase the distance from the energy donor.

[0177] Here, the T1 level of a fluorescent material is often the energy level derived from the luminophore in the material. Therefore, in order to more strictly maintain route A2 while suppressing route A3, it is important to control the distance between the luminophore contained in the energy acceptor compound 132 and the energy donor compound 131. The luminophore refers to the atomic group (skeleton) responsible for the emission of light in a fluorescent material. The luminophore generally has a π bond and preferably contains an aromatic ring, preferably a fused aromatic ring or a fused heteroaromatic ring. In another embodiment, the luminophore can be considered as an atomic group (skeleton) containing an aromatic ring whose transition dipole vector lies on the ring plane. Furthermore, when a fluorescent material has multiple fused aromatic rings or fused heteroaromatic rings, the skeleton with the lowest S1 level among the multiple fused aromatic rings or fused heteroaromatic rings may be considered as the luminophore of the fluorescent material. In some cases, the skeleton of the plurality of fused aromatic rings or fused heteroaromatic rings having the absorption edge on the longest wavelength side is considered to be the luminophore of the fluorescent material, and the luminophore of the fluorescent material can be predicted from the shape of the emission spectrum of each of the plurality of fused aromatic rings or fused heteroaromatic rings.

[0178] Examples of the fused aromatic ring or fused heteroaromatic ring include a phenanthrene skeleton, a stilbene skeleton, an acridone skeleton, a phenoxazine skeleton, a phenothiazine skeleton, etc. In particular, fluorescent materials 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.

[0179] Figure 2A shows a conceptual diagram of a typical fluorescent material, i.e., a fluorescent material without a protecting group, dispersed as a guest material in a host material, and Figure 2B shows a conceptual diagram of a fluorescent material with a protecting group, used in a light-emitting device of one embodiment of the present invention, dispersed as a guest material in a host material. The host material may be interpreted as an energy donor, and the guest material as an energy acceptor. The energy donor corresponds to compound 131 in Figure 1, and the energy acceptor corresponds to compound 132.

[0180] Here, the protecting group functions to increase the distance between the luminophore and the host material. In FIG. 2A, guest material 301 is a normal fluorescent material without a protecting group and contains luminophore 310. Guest material 301 functions as an energy acceptor. On the other hand, in FIG. 2B, guest material 302 contains luminophore 310 and protecting group 320. Also, in FIGS. 2A and 2B, guest materials 301 and 302 are surrounded by host material 330. In FIG. 2A, because the luminophore and host material are close to each other, energy transfer from host material 330 to guest material 301 can occur via both the Förster mechanism (Route A4) and the Dexter mechanism (Route A5). If energy transfer occurs from the triplet excitation energy level of the host material to the triplet excitation energy level of the guest material via the Dexter mechanism, if the guest material is a fluorescent material, the triplet excitation energy will be non-radiatively deactivated, which can lead to a decrease in luminous efficiency.

[0181] 2B, the guest material 302 has a protecting group 320. This allows the distance between the luminophore 310 and the host material 330 to be appropriately increased, thereby suppressing energy transfer via the Dexter mechanism (route A5).

[0182] 2B , in order for the guest material 302 to emit light while the energy transfer via the Dexter mechanism is suppressed, the guest material 302 needs to receive energy from the host material 330 through the energy transfer via the Förster mechanism. In other words, it is preferable to efficiently utilize the energy transfer via the Förster mechanism while suppressing the energy transfer via the Dexter mechanism.

[0183] Therefore, the protecting group 320 preferably extends from the luminophore 310 within a range of 1 nm to 10 nm, more preferably 1 nm to 5 nm. This configuration allows the host material 330 and the guest material to maintain an appropriate distance, suppressing energy transfer from the host material 330 to the guest material 302 via the Dexter mechanism while efficiently utilizing energy transfer via the Förster mechanism. This allows for the fabrication of a light-emitting device with high luminous efficiency.

[0184] The substituent used as the protecting group must have a triplet excitation energy level higher than the T1 level of the luminophore and the host material in order to prevent energy transfer to the protecting group. Since a substituent without a π bond has a high triplet excitation energy level, it is preferable to use a saturated hydrocarbon group as the protecting group.

[0185] Furthermore, since substituents without π-bonds have a low ability to transport carriers (electrons or holes), saturated hydrocarbon groups can maintain an appropriate distance between the luminophore and the host material without having much effect on the excited state or carrier transport properties of the host material.

[0186] In organic compounds that simultaneously have both a substituent without a π bond and a substituent with a π-conjugated system, the frontier orbitals {HOMO (Highest Occupied Molecular Orbital, also called the Highest Occupied Molecular Orbital) and LUMO (Lowest Unoccupied Molecular Orbital, also called the Lowest Unoccupied Molecular Orbital)} are often present on the side of the substituent with a π-conjugated system, and in particular, the lumophore often has a frontier orbital. Here, the overlap of the HOMO and LUMO of the energy donor and energy acceptor is important for energy transfer via the Dexter mechanism. Therefore, by using a saturated hydrocarbon group as a protecting group, the distance between the frontier orbital of the host material (energy donor) and the frontier orbital of the guest material (energy acceptor) can be increased, effectively suppressing energy transfer via the Dexter mechanism.

[0187] Specific examples of the protecting group include an alkyl group having from 1 to 10 carbon atoms, a cycloalkyl group having from 3 to 12 carbon atoms, and a cycloalkyl group having from 7 to 10 carbon atoms and having a crosslinked structure. Since the protecting group is required to increase the distance between the luminophore and the host material, a bulky substituent is preferred. Therefore, an alkyl group having from 3 to 10 carbon atoms, or a substituted or unsubstituted cycloalkyl group having from 3 to 10 carbon atoms, can be suitably used. Bulky branched-chain alkyl groups and cycloalkyl groups are particularly preferred as the alkyl group. Furthermore, if the substituent has a cyclic structure, it becomes a bulky substituent, which is more effective in suppressing energy transfer via the Dexter mechanism, and is therefore more preferred. A cyclohexyl group is particularly preferred from the viewpoint of stability.

[0188] Furthermore, it is preferable that the divalent or higher substituent linking the luminophore and the protecting group is a substituent having a π-conjugated system. This configuration allows the emission color, HOMO level, glass transition temperature, and other physical properties of the guest material to be adjusted. It is also preferable that the protecting group is positioned on the outermost side when viewing the molecular structure from the luminophore.

[0189] In the light-emitting device of one embodiment of the present invention, the organic compound described in Embodiment 1 is used as such a guest material.

[0190] In order to increase the efficiency of energy transfer by the Förster mechanism (to increase the energy transfer rate), it is preferable to increase the concentration ratio of the guest material 301 or the guest material 302 to the host material 330.

[0191] Typically, increasing the concentration of a guest material accelerates the energy transfer rate of the Dexter mechanism, resulting in a decrease in luminescence efficiency, making it difficult to increase the concentration of the guest material. However, in a light-emitting device according to one embodiment of the present invention, a guest material having a protecting group on the luminophore is used in the light-emitting layer, which can suppress energy transfer via the Dexter mechanism. Therefore, even if the concentration of the guest material, which is an energy acceptor, is increased, a decrease in luminescence efficiency due to the Dexter mechanism is unlikely to occur. As a result, the device achieves the contradictory phenomena of suppressing energy transfer via the Dexter mechanism while increasing the energy transfer rate via the Förster mechanism.

[0192] Furthermore, by increasing the rate of energy transfer by the Förster mechanism with the above-mentioned configuration, the donor excitation lifetime of energy in the light-emitting layer is shortened, thereby suppressing deterioration and improving the reliability of the light-emitting device.

[0193] In light-emitting devices, energy transfer always competes with the quenching process due to the influence of degradation products and impurities. However, as described above, one embodiment of the present invention can suppress energy transfer via the Dexter mechanism while increasing the energy transfer rate via the Förster mechanism compared to conventional light-emitting devices. This reduces the impact of competition with the quenching process and extends the life of the light-emitting device.

[0194] The concentration of the guest material relative to the host material is preferably 2 wt% to 30 wt%, more preferably 5 wt% to 20 wt%, and even more preferably 5 wt% to 15 wt%. This configuration increases the energy transfer rate via the Förster mechanism, resulting in a light-emitting device with high luminous efficiency. Furthermore, the shorter excitation lifetime of the energy donor allows for a highly reliable light-emitting device. Note that the above concentrations are those when the material that primarily emits light is used as the guest material and a material other than the guest material is used as the host material in the light-emitting layer.

[0195] <Emitting layer configuration example 2> 4C illustrates an example of the correlation of energy levels in the light-emitting layer 130 of the light-emitting device 150 of one embodiment of the present invention. The light-emitting layer 130 illustrated in FIG. 4A includes a compound 131, a compound 132, and a compound 133. In this example, the compound 132 is the fluorescent material having the protecting group described in Embodiment 1, and the compound 131 and the compound 133 form an exciplex.

[0196] The combination of Compound 131 and Compound 133 may be any combination capable of forming an exciplex. However, it is more preferable that one compound has a hole transporting function (hole transporting property) and the other compound has an electron transporting function (electron transporting property). In this case, a donor-acceptor type exciplex is easily formed, and the exciplex can be efficiently formed. Furthermore, when Compound 131 and Compound 133 are a combination of a compound having hole transporting property and a compound having electron transporting property, the carrier balance can be easily controlled by the mixing ratio. The ratio of the compound having hole transporting property to the compound having electron transporting property is preferably in the range of 1:9 to 9:1 (weight ratio). Furthermore, this configuration makes it easy to control the carrier balance, and therefore, the carrier recombination region can be easily controlled.

[0197] In addition, a combination of host materials that efficiently forms an exciplex is preferably such that the HOMO level of one of Compound 131 and Compound 133 is higher than the HOMO level of the other, and the LUMO level of one is higher than the LUMO level of the other. Note that the HOMO level of Compound 131 may be equivalent to the HOMO level of Compound 133, or the LUMO level of Compound 131 may be equivalent to the LUMO level of Compound 133.

[0198] The LUMO level and HOMO level of a compound can be derived from the electrochemical properties (reduction potential and oxidation potential) of the compound measured by cyclic voltammetry (CV) measurement.

[0199] For example, when compound 131 has hole-transporting properties and compound 133 has electron-transporting properties, the HOMO level of compound 131 {Comp(131)} is preferably higher than the HOMO level of compound 133 {Comp(133)}, and the LUMO level of compound 131 is preferably higher than the LUMO level of compound 133, as shown in the energy band diagram of Figure 4B. Such a correlation of energy levels is preferable because it makes it easier for holes and electrons, which are carriers injected from a pair of electrodes (electrodes 101 and 102), to be injected into compound 131 and compound 133, respectively.

[0200] In addition, in FIG. 4B, ΔE C1 represents the energy difference between the LUMO level and the HOMO level of compound 131, and ΔE C3 represents the energy difference between the LUMO level and the HOMO level of compound 132, and ΔE E is a notation and symbol representing the energy difference between the LUMO level of compound 133 and the HOMO level of compound 131.

[0201] The exciplex formed by Compound 131 and Compound 133 has a HOMO molecular orbital in Compound 131 and a LUMO molecular orbital in Compound 133. The excitation energy of the exciplex is determined by the energy difference (ΔE E), and the energy difference between the LUMO level and the HOMO level of compound 131 (ΔE C1 ) and the energy difference between the LUMO level and the HOMO level of compound 133 (ΔE C3 ) becomes smaller. Therefore, by forming an exciplex between Compound 131 and Compound 133, it becomes possible to form an excited state with lower excitation energy. Furthermore, because of the lower excitation energy, the exciplex can form a stable excited state.

[0202] 4C shows the correlation between the energy levels of the compound 131, the compound 132, and the compound 133 in the light-emitting layer 130. The notations and symbols in FIG. 4C are as follows. ·Comp(131): Compound 131 ·Comp(133): Compound 133 ·Guest(132): Compound 132 ·S C1 : S1 level of compound 131 T C1 :T1 level of compound 131 ·S C3 : S1 level of compound 133 T C3 :T1 level of compound 133 T G :T1 level of compound 132 ·S E : S1 level of the exciplex T E :T1 level of exciplex

[0203] In the light-emitting device of one embodiment of the present invention, the compound 131 and the compound 133 contained in the light-emitting layer 130 form an exciplex. E ) and the T1 level of the exciplex (T E ) are adjacent energy levels (see route A6 in Figure 4C).

[0204] Excitation energy levels of exciplexes (S E and T E) is the S1 level (S C1 and S C3 ), it is possible to form an excited state with lower excitation energy, which allows the driving voltage of the light-emitting device 150 to be reduced.

[0205] The S1 level of the exciplex (S E ) and T1 level (T E ) are adjacent in energy level, so they are prone to reverse intersystem crossing and have TADF properties. Therefore, the exciplex has the function of converting triplet excitation energy into singlet excitation energy by upconversion (Fig. 4C, Route A7). The singlet excitation energy possessed by the exciplex is quickly transferred to compound 132 (Fig. 4C, Route A8). At this time, S E ≧S G In Route A8, the exciplex acts as an energy donor, and Compound 132 acts as an energy acceptor. E ≧S G It is preferable that:

[0206] In order to maintain the efficiency of upconversion in the exciplex, the T1 levels of both Compound 131 and Compound 133, i.e., T C1 and T C3 But, T E It is preferable that the value is equal to or greater than S. E -T C1 ≦0.2 eV and S E -T C3 It is preferable that it is ≦0.2 eV.

[0207] The triplet excitation energy generated in the light-emitting layer 130 passes through the above-mentioned route A6 and energy transfer (route A8) from the S1 level of the exciplex to the S1 level of the guest material, allowing the guest material to emit light.

[0208] In a light-emitting device according to one embodiment of the present invention, a guest material having a protecting group in the luminophore of compound 132 is used. This structure can suppress the energy transfer via the Dexter mechanism represented by route A9, as described above, and can also suppress the deactivation of triplet excitation energy. Therefore, a fluorescent light-emitting device with high luminous efficiency can be obtained.

[0209] Routes A6 to A8, which are the processes of donating excitation energy from an exciplex to a fluorescent material as described above, may be referred to in this specification as ExSET (Exciplex-Singlet Energy Transfer) or ExEF (Exciplex-Enhanced Fluorescence).

[0210] <Emitting layer configuration example 3> In this configuration example, a case where a phosphorescent material is used as one of the compounds forming the exciplex in configuration example 2 will be described.

[0211] In this example, a phosphorescent material having a heavy atom is used as one of the compounds forming the exciplex. As a result, even in the exciplex formed using the phosphorescent material as one of the compounds, intersystem crossing between the singlet state and the triplet state is likely to occur due to the heavy atom effect, making it possible to transition from the triplet excited state to the singlet ground state (i.e., to exhibit phosphorescence).

[0212] Note that examples of heavy atoms contained in the phosphorescent material used in the above structure include Ir, Pt, Os, Ru, and Pd.

[0213] In such exciplexes, the triplet excited energy level (T E ) is the donor level for energy transfer based on the Förster mechanism, so T E The singlet excited energy level (S G ) or more, specifically, T E ≧S G It is preferable that:

[0214] In the light-emitting layer having such a structure, the triplet excitation energy of the generated exciplex is E ) to the singlet excited energy level (S G ) can transfer energy to

[0215] In addition, the S1 level of the exciplex (S E ) and T1 level (T E ) have adjacent energy levels, making it difficult to clearly distinguish between fluorescence and phosphorescence in the emission spectrum. In such cases, it may be possible to distinguish between fluorescence and phosphorescence by the emission lifetime.

[0216] In addition, in this configuration example, since the phosphorescent material functions as an energy donor, the quantum yield of the phosphorescent material may be high or low as long as the energy transfer from the triplet excited energy level of the exciplex to the singlet excited energy level of the guest material is an allowed transition.

[0217] In the energy transfer from the exciplex or phosphorescent material composed of the above-mentioned phosphorescent material to the guest material, the energy transfer from the triplet excited energy level of the energy donor to the singlet excited energy level of the guest material (energy acceptor) is an allowed transition. Therefore, the triplet excited energy of the exciplex is transferred to the S1 level (S G ), the energy transfer process up to light emission is short, and material deterioration and energy loss can be suppressed, which is preferable.

[0218] In a light-emitting device according to one embodiment of the present invention, a guest material having a protecting group on the luminophore is used in the compound 132 described above. This structure can suppress the energy transfer via the Dexter mechanism represented by Route A9, as described above, and can also suppress the deactivation of triplet excitation energy. Therefore, a fluorescent light-emitting device with high luminous efficiency can be obtained.

[0219] <Emitting layer configuration example 4> In this configuration example, a case where a material having TADF properties is used as compound 133 of the light-emitting device in configuration example 2 will be described with reference to FIG. 4D.

[0220] Since compound 133 is a TADF material, it has the function of converting triplet excitation energy to singlet excitation energy by upconversion (Figure 4D Route A 10 The singlet excitation energy of compound 133 can be rapidly transferred to compound 132 (Fig. 4D, Route A). 11 ). At this time, S C3 ≧S G It is preferable that:

[0221] In the light-emitting device of this example, triplet excitation energy is transferred to the compound 132 as a guest material via routes A6 to A8 in FIG. 4D, and via route A 10 and Route A 11 There is a pathway through which triplet excitation energy transfers to compound 132 via the above. The existence of multiple pathways through which triplet excitation energy transfers to the fluorescent material allows the light-emitting device of this configuration to further increase the luminous efficiency.

[0222] In a light-emitting device according to one embodiment of the present invention, a guest material having a protecting group in the luminophore of compound 132 is used. This structure can suppress the energy transfer via the Dexter mechanism represented by route A9, as described above, and can also suppress the deactivation of triplet excitation energy. Therefore, a fluorescent light-emitting device with high luminous efficiency can be obtained.

[0223] In this configuration example, the exciplex and compound 133 function as energy donors, and compound 132 functions as an energy acceptor.

[0224] <Emitting layer configuration example 5> 5A shows a case where four kinds of materials are used for the light-emitting layer 130. In FIG. 5A, the light-emitting layer 130 includes compounds 131, 132, 133, and 134. In this example, the compound 133 is a phosphorescent material. The compound 132 is a fluorescent guest material having a protecting group described in Embodiment 1. The compound 131 is an organic compound that forms an exciplex with the compound 134.

[0225] 5B shows a correlation diagram of the energy levels of compounds 131, 132, 133, and 134 in the light-emitting layer 130. The notations and symbols in FIG. 5B are as follows, and the other notations and symbols are the same as those shown in FIG. 4B. ·S C4 : S1 level of compound 134 T C4 : T1 level of compound 134

[0226] In the light-emitting device of one embodiment of the present invention shown in this configuration example, the compound 131 and the compound 134 form an exciplex. E ) and the T1 level of the exciplex (T E ) are adjacent energy levels (Figure 5B Route A 12 reference).

[0227] The exciplex formed by the above process loses excitation energy and behaves as the two separate substances that formed the exciplex.

[0228] Excitation energy levels of exciplexes (S E and T E ) is the S1 level (S C1 and S C4 ), it is possible to form an excited state with lower excitation energy, which allows the driving voltage of the light-emitting device 150 to be reduced.

[0229] Here, compound 133 is a phosphorescent material, and intersystem crossing between the singlet state and the triplet state is permitted. Therefore, both the singlet excitation energy and the triplet excitation energy of the exciplex are rapidly transferred to compound 133 (Route A). 13 ). At this time, T E ≧T C3 It is preferable that:

[0230] Here, as shown in Figure 5B, T E ≧T C3 ≧S G This is preferable because the excitation energy of compound 133 is efficiently transferred as singlet excitation energy to compound 132, which is a guest material (Route A 14 ).

[0231] In this case, the combination of Compound 131 and Compound 134 may be any combination capable of forming an exciplex, but it is more preferable that one of them is a compound having a hole-transporting property and the other is a compound having an electron-transporting property.

[0232] In addition, as a combination of materials that efficiently form an exciplex, it is preferable that the HOMO level of one of Compound 131 and Compound 134 is higher than the HOMO level of the other, and the LUMO level of one is higher than the LUMO level of the other.

[0233] The correlation between the energy levels of Compound 131 and Compound 134 is not limited to that shown in FIG. 5B. That is, the singlet excitation energy level (S C1 ) is the singlet excited energy level (S C4 ) of Compound 131. C1 ) is the triplet excited energy level (T C4 ) may be higher or lower.

[0234] In the light-emitting device according to one embodiment of the present invention, the compound 131 preferably has a π-electron-deficient skeleton, which lowers the LUMO level of the compound 131 and makes it suitable for forming an exciplex.

[0235] In the light-emitting device according to one embodiment of the present invention, the compound 131 preferably has a π-electron-rich skeleton, which increases the HOMO level of the compound 131 and makes it suitable for forming an exciplex.

[0236] In the light-emitting device according to one embodiment of the present invention, a guest material having a protecting group in the luminophore of the compound 132 is used. 15 Therefore, it is possible to obtain a fluorescent device with high luminous efficiency.

[0237] In addition, Route A, in which excitation energy is donated from the exciplex to compound 133 as shown above, 12 and A 13 This process is sometimes referred to as ExTET (Exciplex-Triplet Energy Transfer) in this specification, etc. Therefore, this configuration example can be said to be a configuration in which a fluorescent material having a protecting group is mixed into an emitting layer that can utilize ExTET.

[0238] <Configuration Example 6 of Light-Emitting Layer> In this configuration example, a case will be described in which a material having TADF properties is used as the compound 134 described in the above-mentioned configuration example 5 of the light-emitting layer.

[0239] 5C, the light-emitting layer 130 includes compounds 131, 132, 133, and 134. In one embodiment of the present invention, the compound 133 has a function of converting triplet excitation energy into light emission. The compound 132 is a fluorescent guest material having the protecting group described in Embodiment 1. The compound 131 is an organic compound that forms an exciplex with the compound 134.

[0240] Here, since compound 134 is a TADF material, compound 134 that does not form an exciplex has the function of converting triplet excitation energy to singlet excitation energy by upconversion (Figure 5C Route A 16 The singlet excitation energy of compound 134 is rapidly transferred to compound 132 (Fig. 5C Route A 17 ). At this time, S C4 ≧S G It is preferable that:

[0241] In the light-emitting device according to one embodiment of the present invention having the light-emitting layer of this configuration example, Route A 12 Route A 14 Route A: Triplet excitation energy is transferred to the guest material, compound 132, via route B. 16 and Route A 17 There is a route where the triplet excitation energy transfers to compound 132 via the above. The existence of multiple routes where the triplet excitation energy transfers to the fluorescent material can further increase the luminescence efficiency. Route A 14 In this case, compound 133 functions as an energy donor and compound 132 functions as an energy acceptor. 17 In this example, compound 134 functions as an energy donor and compound 132 functions as an energy acceptor.

[0242] In the light-emitting device according to one embodiment of the present invention, a guest material having a protecting group in the luminophore of the compound 132 is used. 15 Therefore, it is possible to obtain a fluorescent device with high luminous efficiency.

[0243] <Emitting Layer Configuration Example 7> The light-emitting layer 130 shown in FIG. 6A includes a compound 131, a compound 132, and a compound 133. In one embodiment of the present invention, the compound 132 is a fluorescent material having the protecting group described in Embodiment 1. The compound 133 has a function of converting triplet excitation energy into light emission. In this example, the case where the compound 133 is a phosphorescent material will be described.

[0244] 6B shows an example of the correlation of energy levels in the light-emitting layer 130 of the light-emitting device 150 according to one embodiment of the present invention. The notations and symbols in FIG. 6B are as follows. ·Comp(131): Compound 131 ·Comp(133): Compound 133 ·Guest(132): Compound 132 ·S C1 : S1 level of compound 131 T C1 :T1 level of compound 131 T C3 :T1 level of compound 133 T G :T1 level of compound 132 ·S G : S1 level of compound 132

[0245] In the light-emitting device of one embodiment of the present invention, singlet excitons and triplet excitons are generated mainly by carrier recombination in the compound 131 contained in the light-emitting layer 130. Here, since the compound 133 is a phosphorescent material, T C3 ≦T C1 By selecting materials with this relationship, both the singlet and triplet excitation energies generated in compound 131 can be converted to the T C3 (Figure 6B Route A 18 ).

[0246] When the phosphorescent material is the energy donor, energy transfer from the triplet excited energy level of the energy donor to the singlet excited energy level of the guest material (energy acceptor) is preferred because it is an allowed transition. 19 The S1 level (S G ) can be moved to Route A. 19 In this case, compound 133 functions as an energy donor and compound 132 functions as an energy acceptor. C3 ≧S G This is preferable because the excitation energy of the compound 133 is efficiently transferred to the singlet excited state of the compound 132, which is a guest material.

[0247] In the light-emitting device according to one embodiment of the present invention, a guest material having a protecting group on the luminophore is used in Compound 132. With this structure, Route A can be realized as described above. 20 Therefore, it is possible to obtain a fluorescent device with high luminous efficiency.

[0248] <Emitting Layer Configuration Example 8> FIG. 6C illustrates an example of the correlation of energy levels in the light-emitting layer 130 of the light-emitting device 150 of one embodiment of the present invention. The light-emitting layer 130 illustrated in FIG. 6C includes a compound 131, a compound 132, and a compound 133. In one embodiment of the present invention, the compound 132 is the fluorescent material having the protecting group described in Embodiment 1. The compound 133 has a function of converting triplet excitation energy into light emission. In this configuration example, the case where the compound 133 is a compound having TADF properties will be described.

[0249] The notations and symbols in FIG. 6C are as follows, and the other notations and symbols are the same as those shown in FIG. 6B. ·S C3 : S1 level of compound 133

[0250] In the light-emitting device according to one embodiment of the present invention, singlet excitons and triplet excitons are generated mainly by carrier recombination in the compound 131 contained in the light-emitting layer 130. C3 ≦S C1 KatsuT C3 ≦T C1 By selecting materials with this relationship, both the singlet excitation energy and triplet excitation energy generated in compound 131 can be converted to S of compound 133. C3 and T C3 (Figure 6C Route A 21 ) Note that some carriers can be reconjugated with compound 133.

[0251] Here, since compound 134 is a TADF material, it has the function of converting triplet excitation energy into singlet excitation energy by upconversion (Figure 6C Route A 22 ) Furthermore, the singlet excitation energy of compound 133 can be rapidly transferred to compound 132 (Figure 6C Route A 23 ). At this time, S C3 ≧S G Specifically, a tangent line is drawn at the base of the fluorescence spectrum of Compound 133 on the short wavelength side, and the energy of the wavelength of the extrapolated line is expressed as S C3 The energy of the wavelength at the absorption edge of the absorption spectrum of compound 132 is S G When this is done, S C3 ≧S G Route A is preferred. 21 Route A 23 Through this process, the triplet excitation energy in the light-emitting layer 130 can be converted into fluorescent light from the compound 132. 23 In this example, compound 133 functions as an energy donor and compound 132 functions as an energy acceptor.

[0252] In the light-emitting device according to one embodiment of the present invention, a guest material having a protecting group on the luminophore is used in Compound 132. With this structure, Route A can be realized as described above. 24Therefore, it is possible to obtain a fluorescent device with high luminous efficiency.

[0253] <Material> Next, the components of the light-emitting device according to one embodiment of the present invention will be described in detail below.

[0254] <Light-emitting layer> Materials that can be used for the light-emitting layer 130 are described below. The light-emitting layer of the light-emitting device of one embodiment of the present invention uses an energy donor that has a function of converting triplet excitation energy into light emission and an energy acceptor that has a luminophore and a protecting group. Examples of materials that have a function of converting triplet excitation energy into light emission include TADF materials, exciplexes, and phosphorescent materials.

[0255] Examples of the luminophore contained in compound 132 that functions as an energy acceptor include a phenanthrene skeleton, a stilbene skeleton, an acridone skeleton, a phenoxazine skeleton, a phenothiazine skeleton, etc. Fluorescent materials 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 particularly preferred because of their high fluorescence quantum yield.

[0256] The protecting group is preferably an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a branched alkyl group having 3 to 10 carbon atoms, or a trialkylsilyl group having 3 to 12 carbon atoms.

[0257] Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group, a pentyl group, and a hexyl group, but a branched chain alkyl group having 3 to 10 carbon atoms, as described below, is particularly preferred. However, the alkyl group is not limited to these.

[0258] Examples of cycloalkyl groups having 3 to 10 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclohexyl group, a norbornyl group, and an adamantyl group. The cycloalkyl group is not limited to these. When the cycloalkyl group has a substituent, examples of the substituent include alkyl groups having 1 to 7 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, and a hexyl group; cycloalkyl groups having 5 to 7 carbon atoms, such as a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and an 8,9,10-trinorbornanyl group; and aryl groups having 6 to 12 carbon atoms, such as a phenyl group, a naphthyl group, and a biphenyl group.

[0259] Examples of branched alkyl groups having 3 to 10 carbon atoms include an isopropyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a neopentyl group, an isohexyl group, a 3-methylpentyl group, a 2-methylpentyl group, a 2-ethylbutyl group, a 1,2-dimethylbutyl group, a 2,3-dimethylbutyl group, etc. The branched alkyl group is not limited to these.

[0260] Examples of the trialkylsilyl group having 3 to 12 carbon atoms include a trimethylsilyl group, a triethylsilyl group, a tert-butyldimethylsilyl group, etc. The trialkylsilyl group is not limited to these.

[0261] Furthermore, the molecular structure of the energy acceptor is preferably a structure in which the luminophore is bonded to two or more aryl groups, each of which has at least one protecting group. It is even more preferable that at least two protecting groups are bonded to each of the aryl groups. This is because the greater the number of protecting groups, the greater the effect of suppressing energy transfer via the Dexter mechanism when the guest material is used in the light-emitting layer. In order to suppress an increase in molecular weight and maintain sublimability, the aryl group is preferably a phenyl group. Furthermore, a structure in which the luminophore and the aryl group are bonded via a nitrogen atom possessed by the luminophore is preferred.

[0262] Furthermore, by bonding two or more aryl groups to the luminophore, it is possible to obtain a fluorescent material with high quantum yield while adjusting the emission color. Furthermore, it is preferable that the aryl groups are bonded to the luminophore at positions symmetrical to each other. This configuration allows for the production of a fluorescent material with high quantum yield.

[0263] Alternatively, instead of directly introducing a protecting group to the luminophore, the protecting group may be introduced via an aryl group. This configuration allows the protecting group to be positioned so as to cover the luminophore, which is preferable because it allows the distance between the host material and the luminophore to be increased from any direction. Furthermore, when the protecting group is not directly bonded to the luminophore, it is preferable to introduce four or more protecting groups per luminophore.

[0264] As shown in Figure 3, it is preferable that at least one of the atoms constituting the multiple protecting groups is located directly on one face of the luminophore, i.e., the fused aromatic ring or fused heteroaromatic ring, and at least one of the atoms constituting the multiple protecting groups is located directly on the other face of the fused aromatic ring or fused heteroaromatic ring. Specific methods for achieving this include the following: That is, the luminophore, i.e., the fused aromatic ring or fused heteroaromatic ring, is bonded to two or more phenyl groups, and each of the two or more phenyl groups independently has a protecting group at the ortho position.

[0265] This configuration allows the ortho-protecting group on the phenyl group to be positioned directly above the fused aromatic ring or fused heteroaromatic ring, which is the luminophore, as shown in Figure 3. As a result, the upper and lower surfaces of the fused aromatic ring or fused heteroaromatic ring can be efficiently covered, suppressing energy transfer via the Dexter mechanism.

[0266] As the energy acceptor material described above, the organic compound shown in the first embodiment is particularly preferable.

[0267] A TADF material that can be used for any of Compound 131, Compound 133, and Compound 134 preferably has a skeleton having hole transport properties and a skeleton having electron transport properties. Alternatively, it preferably has a π-electron-rich skeleton or an aromatic amine skeleton and a π-electron-deficient skeleton. This facilitates the formation of a donor-acceptor excited state within the molecule. Furthermore, it preferably has a structure in which a skeleton having electron transport properties and a skeleton having hole transport properties are directly bonded to each other so that both donor and acceptor properties are strong within the molecule. Alternatively, it preferably has a structure in which a π-electron-rich skeleton or an aromatic amine skeleton is directly bonded to a π-electron-deficient skeleton. By strengthening both donor and acceptor properties within the molecule, it is possible to reduce the overlap between the region where the molecular orbitals in the HOMO and the region where the molecular orbitals in the LUMO are distributed, thereby reducing the energy difference between the singlet excitation energy level and the triplet excitation energy level. It also makes it possible to maintain the triplet excitation energy level at a high energy. The energy difference between the S1 level and the T1 level of the TADF material is preferably small, specifically greater than 0 eV and equal to or less than 0.2 eV.

[0268] As the TADF material, for example, the following materials can be used.

[0269] Examples include fullerene and its derivatives, acridine derivatives such as proflavine, eosin, etc. Also included 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).

[0270] [ka]

[0271] In addition, heterocyclic compounds having either or both of a π-electron rich skeleton and a π-electron deficient skeleton can also be used as TADF materials composed of a single material. Specifically, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 2-[ 4-(10H-phenoxazin-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: PXZ-TRZ), 3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthene-9- one (abbreviation: ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), 10-phenyl-10H,10'H-spiro[acridine-9,9'-anthracene]-10'-one (abbreviation: ACRSA), 4-(9'-phenyl-3,3'-bi-9H-carbazol-9-yl)benzofuro[3,2-d]pyrimidine ( Examples of such heterocyclic compounds include 4-[4-(9'-phenyl-3,3'-bi-9H-carbazol-9-yl)phenyl]benzofuro[3,2-d]pyrimidine (abbreviation: 4PCCzBfpm), 4-[4-(9'-phenyl-3,3'-bi-9H-carbazol-9-yl)phenyl]benzofuro[3,2-d]pyrimidine (abbreviation: 4PCCzPBfpm), and 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02). These heterocyclic compounds have a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring, and therefore have high electron-transporting and hole-transporting properties, making them preferable. Among the heteroaromatic ring-containing skeletons, pyridine skeletons, diazine skeletons (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), and triazine skeletons are preferred due to their stability and reliability.In particular, benzofuropyrimidine skeleton, benzothienopyrimidine skeleton, benzofuropyrazine skeleton, and benzothienopyrazine skeleton are preferred because of their high acceptor properties and good reliability. Furthermore, among skeletons having a π-electron-rich heteroaromatic ring, acridine skeleton, phenoxazine skeleton, phenothiazine skeleton, furan skeleton, thiophene skeleton, and pyrrole skeleton are preferred because of their stability and good reliability. The dibenzofuran skeleton is preferred as the furan skeleton, and the dibenzothiophene skeleton is preferred as the thiophene skeleton. Furthermore, the indole skeleton, carbazole skeleton, bicarbazole skeleton, and 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole skeleton are particularly preferred as the pyrrole 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 donor property of the π-electron-rich heteroaromatic ring and the acceptor property of the π-electron-deficient heteroaromatic ring are both strong, and the difference between the energy levels of the singlet excited state and the triplet excited state is small. 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. Examples of π-electron-rich skeletons that can be used include aromatic amine skeletons and phenazine skeletons. Examples of π-electron-deficient skeletons that can be used include xanthene skeletons, thioxanthene dioxide skeletons, oxadiazole skeletons, triazole skeletons, imidazole skeletons, anthraquinone skeletons, boron-containing skeletons such as phenylborane and boranthrene, aromatic rings or heteroaromatic rings having a nitrile group or a cyano group such as benzonitrile or cyanobenzene, carbonyl skeletons such as benzophenone, phosphine oxide skeletons, and sulfone skeletons. In this way, a π-electron-deficient skeleton and 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.

[0272] [ka]

[0273] Phosphorescent materials that can be used in any of Compounds 131, 133, and 134 include organometallic complexes or metal complexes of iridium, rhodium, or platinum. Examples include platinum complexes and organic iridium complexes with porphyrin ligands. Of these, organic iridium complexes, such as iridium orthometal complexes, are preferred. Examples of orthometallated ligands include 4H-triazole ligands, 1H-triazole ligands, imidazole ligands, pyridine ligands, pyrimidine ligands, pyrazine ligands, and isoquinoline ligands. In this case, Compound 133 (phosphorescent material) has an absorption band associated with triplet MLCT (Metal to Ligand Charge Transfer) transitions. When using the phosphorescent material as an energy donor, it is preferable to select a material such that the emission peak of the phosphorescent material overlaps with the longest wavelength (lowest energy) absorption band of Compound 132 (fluorescent material). This makes it possible to provide a light-emitting device with dramatically improved luminous efficiency. Specific examples of the phosphorescent material include the following:

[0274] An example of a substance having a blue or green emission peak is tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN 2]phenyl-κC}iridium(III) (abbreviation: Ir(mpptz-dmp)3), tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III) (abbreviation: Ir(Mptz)3), tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: Ir(iPr Organometallic iridium complexes with a 4H-triazole skeleton, such as tris[3-(5-biphenyl)-5-isopropyl-4-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviated as Ir(iPr5btz)3), and tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviated as Ir(iPr5btz)3). Organometallic iridium complexes with 1H-triazole skeletons, such as tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: Ir(Prptz1-Me)3), and organometallic iridium complexes with imidazole skeletons, 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 having a phenylpyridine derivative having an electron-withdrawing group as a ligand, such as iridium(III) acetylacetonate (abbreviation: FIr(acac)). Among the above, organometallic iridium complexes having a nitrogen-containing five-membered heterocyclic skeleton, such as a 4H-triazole skeleton, a 1H-triazole skeleton, or an imidazole skeleton, are particularly preferred because they have high triplet excitation energy and are also excellent in reliability and luminous efficiency.

[0275] Furthermore, examples of substances having a green or yellow emission peak include tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: Ir(mppm)3), tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation: Ir(tBuppm)3), (acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium(III) (abbreviation: Ir(mppm)2(acac)), (acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidinato)iridium(III) (abbreviation: Ir(mppm)2(acac)), and (acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidinato)iridium(III). Iridium(III) (abbreviation: Ir(tBuppm)2(acac)), (acetylacetonato)bis[4-(2-norbornyl)-6-phenylpyrimidinato]iridium(III) (abbreviation: Ir(nbppm)2(acac)), (acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: Ir(mpmppm)2(acac)), (acetylacetonato)bis{4,6-dimethyl-2-[6-(2,6-dimethylphenyl)-4-pyrimidinyl-κN 3]phenyl-κC}iridium(III) (abbreviation: Ir(dmppm-dmp)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 (abbreviated as Ir(ppy)2(acac)), bis(benzo[h]quinolinato)iridium(III) acetylacetonate (abbreviated as Ir(bzq)2(acac)), tris(benzo[h]quinolinato)iridium(III) (abbreviated as Ir(bzq)3), tris(2-phenylquinolinato-N,C 2’ ) Iridium(III) (abbreviation: Ir(pq)3), bis(2-phenylquinolinato-N,C 2’ Organometallic iridium complexes with a pyridine skeleton, such as iridium(III) acetylacetonate (abbreviated as Ir(pq)2(acac)), and bis(2,4-diphenyl-1,3-oxazolato-N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: Ir(dpo)2(acac)), bis{2-[4'-(perfluorophenyl)phenyl]pyridinato-N,C 2’ Iridium(III) acetylacetonate (abbreviation: Ir(p-PF-ph)2(acac)), bis(2-phenylbenzothiazolato-N,C 2’Examples include organometallic iridium complexes such as iridium(III) acetylacetonate (abbreviated as Ir(bt)2(acac)), and rare earth metal complexes such as tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviated as Tb(acac)3(Phen)). Among the above, organometallic iridium complexes having a pyrimidine skeleton are particularly preferred because of their outstanding reliability and luminous efficiency.

[0276] Furthermore, examples of substances having a yellow or red emission peak include compounds having a pyrimidine skeleton, such as (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III) (abbreviation: Ir(5mdppm)2(dibm)), bis[4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: Ir(5mdppm)2(dpm)), and bis[4,6-di(naphthalen-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: Ir(d1npm)2(dpm)). and organometallic iridium complexes with pyrazine skeletons such as (acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: Ir(tppr)2(acac)), bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: Ir(tppr)2(dpm)), and (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: Ir(Fdpq)2(acac)). 2’ ) Iridium(III) (abbreviation: Ir(piq)3), bis(1-phenylisoquinolinato-N,C 2’Examples of suitable iridium complexes 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-porphyrin platinum(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)). Among the above, organometallic iridium complexes with a pyrimidine skeleton are particularly preferred due to their outstanding reliability and luminous efficiency. Furthermore, organometallic iridium complexes having a pyrazine skeleton can emit red light with good chromaticity.

[0277] Furthermore, when any of Compound 131, Compound 133, and Compound 134 forms an exciplex, examples thereof include, in addition to the above-mentioned TADF materials and phosphorescent materials, zinc- and aluminum-based metal complexes, oxadiazole derivatives, triazole derivatives, benzimidazole derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, pyrimidine derivatives, triazine derivatives, pyridine derivatives, bipyridine derivatives, and phenanthroline derivatives. Other examples include aromatic amines and carbazole derivatives.

[0278] In addition, the following hole transporting materials and electron transporting materials can be used.

[0279] As the hole transporting material, a material having a higher hole transporting property than electron transporting property can be used. -6 cm 2 It is preferable that the hole transport material has a hole mobility of 1 / Vs or more. Specifically, aromatic amines, carbazole derivatives, aromatic hydrocarbons, stilbene derivatives, etc. can be used. The hole transport material may also be a polymer compound.

[0280] Examples of these materials with high hole transport properties include aromatic amine compounds such as N,N'-di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), N,N'-bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviation: DNTPD), and 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B).

[0281] Specific examples of carbazole derivatives include 3-[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA1), 3,6-bis[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA2), and 3,6-bis[N-(4-diphenylaminophenyl)-N-(1-naphthyl)amino]-9-phenylcarbazole (abbreviation: PCzTP N2), 3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2), 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1), and the like can be mentioned.

[0282] Other carbazole derivatives that can be used include 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB), 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA), and 1,4-bis[4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene.

[0283] 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 butyl-9,10-bis[2-(1-naphthyl)phenyl]anthracene, 9,10-bis[2-(1-naphthyl)phenyl]anthracene, 2,3,6,7-tetramethyl-9,10-di(1-naphthyl)anthracene, 2,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene, 9,9'-bianthryl, 10,10'-diphenyl-9,9'-bianthryl, 10,10'-bis(2-phenylphenyl)-9,9'-bianthryl, 10,10'-bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9'-bianthryl, anthracene, tetracene, rubrene, perylene, 2,5,8,11-tetra(tert-butyl)perylene, etc. In addition, pentacene, coronene, etc. can also be used. Thus, 1×10 -6 cm 2 It is more preferable to use an aromatic hydrocarbon having a hole mobility of 1 / Vs or more and having 14 to 42 carbon atoms.

[0284] The aromatic hydrocarbon may have a vinyl skeleton. Examples of aromatic hydrocarbons having a vinyl group include 4,4'-bis(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi) and 9,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene (abbreviation: DPVPA).

[0285] 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.

[0286] Furthermore, examples of materials with high hole transport properties include 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB or α-NPD), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4',4''-tris(carbazol-9-yl)triphenylamine (abbreviation: TCTA), 4,4',4''-tris[N-(1-naphthyl)-N-phenylamino]triphenylamine (abbreviation: 1'-TNATA), 4,4',4''-tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA), 4,4',4''-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (abbreviation: MTDATA), 4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), N-(9,9-dimethyl-2-diphenylamino-9H-fluoren-7-yl)diphenylamine (abbreviation: DPNF), 2-[N-(4- diphenylaminophenyl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: DPASF), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-Di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviated as PCBNBB), 4-phenyldiphenyl-(9-phenyl-9H-carbazol-3-yl)amine (abbreviated as PCA1BP), N,N'-bis(9-phenylcarbazol-3-yl)-N,N'-diphenylbenzene-1,3-diamine (abbreviated as PCA2B), N,N',N''-triphenyl-N,N',N''-tris(9-phenyl) Carbazol-3-yl)benzene-1,3,5-triamine (abbreviation: PCA3B), N-(4-biphenyl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9-phenyl-9H-carbazol-3-amine (abbreviation: PCBiF), N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), 9,9-dimethyl N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]spiro-9,9'-bifluoren-2-amine (abbreviation: PCBASF), 2-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: PCASF), 2,7-bis[N- Aromatic amine compounds such as (4-diphenylaminophenyl)-N-phenylamino]-spiro-9,9'-bifluorene (abbreviation: DPA2SF), N-[4-(9H-carbazol-9-yl)phenyl]-N-(4-phenyl)phenylaniline (abbreviation: YGA1BP), and N,N'-bis[4-(carbazol-9-yl)phenyl]-N,N'-diphenyl-9,9-dimethylfluorene-2,7-diamine (abbreviation: YGA2F) can be used. In addition, 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 3-[4-(9-phenanthryl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPPn), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II), 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II), 1,3,5-tri(dibenzothiophen-4-yl)-benzene (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran Examples of compounds that can be used include amine compounds such as 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviated as DBTFLP-III), 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviated as DBTFLP-IV), and 4-[3-(triphenylen-2-yl)phenyl]dibenzothiophene (abbreviated as mDBTPTp-II), carbazole compounds, thiophene compounds, furan compounds, fluorene compounds, triphenylene compounds, and phenanthrene compounds. The substances mentioned here are mainly 1×10, -6 cm 2 However, other substances may be used as long as they have a higher hole transporting property than electron transporting property.

[0287] As the electron transporting material, a material having a higher electron transporting property than a hole transporting property can be used. -6 cm 2 It is preferable that the material has an electron mobility of 1 / Vs or more. Materials that readily accept electrons (materials having electron transport properties) include π-electron-deficient heteroaromatic compounds such as nitrogen-containing heteroaromatic compounds and metal complexes. Specific examples include metal complexes having quinoline ligands, benzoquinoline ligands, oxazole ligands, or thiazole ligands, oxadiazole derivatives, triazole derivatives, phenanthroline derivatives, pyridine derivatives, bipyridine derivatives, and pyrimidine derivatives.

[0288] Examples of suitable metal complexes include tris(8-quinolinolato)aluminum(III) (Alq), tris(4-methyl-8-quinolinolato)aluminum(III) (Almq), bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (BeBq), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (BAlq), and bis(8-quinolinolato)zinc(II) (Znq). Metal complexes with oxazole or thiazole ligands, such as bis[2-(2-benzoxazolyl)phenolato]zinc(II) (ZnPBO) and bis[2-(2-benzothiazolyl)phenolato]zinc(II) (ZnBTZ), can also be used. In addition to metal complexes, we have also developed 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiazolinone) Heterocyclic compounds such as 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), and 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II).h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDBTPDBq-II), and 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDBTPDBq-II). 4,6-bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazole Heterocyclic compounds having a diazine skeleton such as 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), heterocyclic compounds having a triazine skeleton such as 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy) and 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), and heteroaromatic compounds such as 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOs) can also be used. Polymer compounds such as poly(2,5-pyridinediyl) (abbreviated as PPy), poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)] (abbreviated as PF-Py), and poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2'-bipyridine-6,6'-diyl)] (abbreviated as PF-BPy) can also be used. The substances mentioned here are mainly 1×10, -6 cm 2 It is to be noted that any substance other than those mentioned above may be used as long as it has a higher electron transporting property than a hole transporting property.

[0289] When the compound forming the exciplex does not contain a TADF material or a phosphorescent material, it is preferable that one of them has a function of transporting electrons and the other has a function of transporting holes. It is also preferable that one of them has a π-electron-deficient heteroaromatic ring and the other has a π-electron-rich heteroaromatic ring.

[0290] In addition, it is preferable to select Compounds 131 and 133 or Compounds 131 and 134, and Compound 132 (fluorescent material) so that the emission peak of the exciplex overlaps with the longest wavelength (lowest energy) absorption band of Compound 132 (fluorescent material). This allows for a light-emitting device with dramatically improved luminous efficiency.

[0291] Furthermore, when forming an exciplex using a phosphorescent material as one of the materials, the phosphorescent material does not need to emit light at room temperature, but only needs to emit light at room temperature when the exciplex is formed. In this case, for example, Ir(ppz)3 can be used as the phosphorescent material.

[0292] The light-emitting layer 130 can also be configured with two or more layers. For example, when the light-emitting layer 130 is formed by stacking a first light-emitting layer and a second light-emitting layer in this order from the hole-transport layer side, a substance having a hole-transport property can be used as a host material for the first light-emitting layer, and a substance having an electron-transport property can be used as a host material for the second light-emitting layer.

[0293] Furthermore, the light-emitting layer 130 may contain a material (compound 135 (not shown)) other than compounds 131, 132, 133, and 134. In this case, in order for compounds 131 and 133 (or compound 134) to efficiently form an exciplex, it is preferable that the HOMO level of one of compounds 131 and 133 (or compound 134) is the highest among the materials in the light-emitting layer 130, and the LUMO level of the other compound is the lowest among the materials in the light-emitting layer 130. By establishing such a correlation in energy levels, the reaction of compound 131 and compound 135 to form an exciplex can be suppressed.

[0294] For example, when compound 131 has hole-transporting properties and compound 133 (or compound 134) has electron-transporting properties, the HOMO level of compound 131 is preferably higher than the HOMO level of compound 133 and the HOMO level of compound 135, and the LUMO level of compound 133 is preferably lower than the LUMO level of compound 131 and the LUMO level of compound 135. In this case, the LUMO level of compound 135 may be higher or lower than the LUMO level of compound 131. Furthermore, the HOMO level of compound 135 may be higher or lower than the HOMO level of compound 133.

[0295] Compound 135 is not particularly limited, and examples thereof include tris(8-quinolinolato)aluminum(III) (abbreviation: Alq), tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviation: Almq3), bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq2), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (abbreviation: BAlq), bis(8-quinolinolato)zinc(II), metal complexes such as bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: Znq), bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO), and bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ); 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: O XD-7), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), bathophenanthroline (abbreviation: BPhen), bathocuproine (abbreviation: BCP), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazo and aromatic amine compounds such as 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB or α-NPD), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), and 4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB).Further, examples of condensed polycyclic aromatic compounds include anthracene derivatives, phenanthrene derivatives, pyrene derivatives, chrysene derivatives, and dibenzo[g,p]chrysene derivatives. Specific examples include 9,10-diphenylanthracene (abbreviation: DPAnth), N,N-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: CzAlPA), 4-(10-phenyl-9-anthryl)triphenylamine (abbreviation: DPhPA), 4-(9H-carbazol-9-yl)-4-methyl- '-(10-Phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole-3-amine (abbreviation: PCAPA), N,9-diphenyl-N-{4-[4-(10-phenyl-9-anthryl)phenyl]phenyl}-9H-carbazole-3-amine (abbreviation: PCAPBA), N,9-diphenyl-N-(9,10-diphenyl-2-anthryl)-9H-carbazole-3-amine (abbreviation: 2PCA PA), 6,12-dimethoxy-5,11-diphenylchrysene, N,N,N',N',N'',N'',N''',N'''-octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA), 3,6-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: DPCzPA), 9,10-bis(3,5-diphenylphenyl )anthracene (abbreviation: DPPA), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA), 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 9,9'-bianthryl (abbreviation: BANT), 9,9'-(stilbene-3,3'-diyl)diphenanthrene (abbreviation: DPNS), 9,9'-(stilbene-4,4'-diyl)diphenanthrene (abbreviation: DPNS2), 1,3,5-tri(1-pyrenyl)benzene (abbreviation: TPB3), and the like.Furthermore, one or more substances having an energy gap larger than the energy gap of Compound 131 and Compound 132 may be selected from these and known substances and used.

[0296] <Pair of electrodes> The electrodes 101 and 102 function to inject holes and electrons into the light-emitting layer 130. The electrodes 101 and 102 can be formed using a metal, an alloy, a conductive compound, or a mixture or laminate thereof. A typical example of a metal is aluminum (Al). Other examples include transition metals such as silver (Ag), tungsten, chromium, molybdenum, copper, and titanium; alkali metals such as lithium (Li) and cesium; and Group 2 metals such as calcium and magnesium (Mg). A rare earth metal such as ytterbium (Yb) may also be used as a transition metal. Examples of alloys include alloys containing the above metals, such as MgAg and AlLi. Examples of conductive compounds include metal oxides such as indium tin oxide (ITO), indium tin oxide containing silicon or silicon oxide (abbreviated as ITSO), indium zinc oxide, and indium oxide containing tungsten and zinc. As the conductive compound, an inorganic carbon-based material such as graphene may be used. As described above, one or both of the electrode 101 and the electrode 102 may be formed by stacking a plurality of such materials.

[0297] Furthermore, light emitted from the light-emitting layer 130 is extracted through one or both of the electrodes 101 and 102. Therefore, at least one of the electrodes 101 and 102 has a function of transmitting visible light. A conductive material having a function of transmitting light has a visible light transmittance of 40% or more and 100% or less, preferably 60% or more and 100% or less, and a resistivity of 1×10 -2Examples of suitable conductive materials include a material with a resistivity of Ω·cm or less. The electrode for extracting light may be made of a conductive material that has both a light transmitting function and a light reflecting function. The conductive material has a visible light reflectance of 20% or more and 80% or less, preferably 40% or more and 70% or less, and a resistivity of 1×10 -2 Examples of such materials include conductive materials with a resistivity of Ω·cm or less. When a material with low optical transparency, such as a metal or alloy, is used for the electrode that extracts light, one or both of the electrodes 101 and 102 may be formed to a thickness that allows visible light to pass through (for example, a thickness of 1 nm to 10 nm).

[0298] In this specification and the like, the electrode having the function of transmitting light may be made of a material that has the function of transmitting visible light and is conductive, and includes, for example, an oxide conductor layer such as the above-mentioned ITO, as well as an oxide semiconductor layer or an organic conductor layer containing an organic substance. Examples of the organic conductor layer containing an organic substance include a layer containing a composite material obtained by mixing an organic compound and an electron donor (donor), and a layer containing a composite material obtained by mixing an organic compound and an electron acceptor (acceptor). In addition, the resistivity of the transparent conductive layer is preferably 1×10 5 Ω·cm or less, more preferably 1×10 4 Ω·cm or less.

[0299] The electrode 101 and the electrode 102 can be formed by any suitable method, such as sputtering, vapor deposition, printing, coating, MBE (Molecular Beam Epitaxy), CVD, pulsed laser deposition, or ALD (Atomic Layer Deposition).

[0300] <Hole injection layer> The hole injection layer 111 has the function of promoting hole injection from one of the pair of electrodes (electrode 101 or electrode 102) by reducing the hole injection barrier, and is formed, for example, from a transition metal oxide, a phthalocyanine derivative, or an aromatic amine. Examples of transition metal oxides include molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, and manganese oxide. Examples of phthalocyanine derivatives include phthalocyanine and metal phthalocyanine. Examples of aromatic amines include benzidine derivatives and phenylenediamine derivatives. Polymer compounds such as polythiophene and polyaniline can also be used, and a representative example is poly(ethylenedioxythiophene) / poly(styrenesulfonic acid), which is a self-doped polythiophene.

[0301] The hole injection layer 111 may be a layer containing a composite material of a hole transporting material and a material exhibiting electron accepting properties. Alternatively, a stack of a layer containing a material exhibiting electron accepting properties and a layer containing a hole transporting material may be used. Charges can be exchanged between these materials in a steady state or under the presence of an electric field. Examples of materials exhibiting electron accepting properties include organic acceptors such as quinodimethane derivatives, chloranil derivatives, and hexaazatriphenylene derivatives. Specific examples include compounds having an electron-withdrawing group (especially a halogen group such as a fluoro group or a cyano group), such as 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT-CN), and 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviation: F6-TCNNQ). In particular, compounds such as HAT-CN in which an electron-withdrawing group is bonded to a fused aromatic ring having multiple heteroatoms are thermally stable and preferred. Radialene derivatives having electron-withdrawing groups (especially halogen groups such as fluoro groups or cyano groups) are preferred because of their extremely high electron-accepting properties. Specific examples include α,α',α''-1,2,3-cyclopropanetriylidenetris[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α',α''-1,2,3-cyclopropanetriylidenetris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], and α,α',α''-1,2,3-cyclopropanetriylidenetris[2,3,4,5,6-pentafluorobenzeneacetonitrile]. Transition metal oxides, such as oxides of metals from Groups 4 to 8, can also be used. Specific examples include vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, and rhenium oxide. Among these, molybdenum oxide is preferred because it is stable in the air, has low hygroscopicity, and is easy to handle.

[0302] As the hole transporting material, a material having a higher hole transporting property than electron transporting property can be used.-6 cm 2 It is preferable that the material has a hole mobility of 1 / Vs or more. Specifically, aromatic amines and carbazole derivatives listed as hole transport materials that can be used for the light-emitting layer 130 can be used. Also, aromatic hydrocarbons and stilbene derivatives can be used. The hole transport material may also be a polymer compound.

[0303] 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. Thus, 1×10 -6 cm 2 It is more preferable to use an aromatic hydrocarbon having a hole mobility of 14 to 42 carbon atoms and having a hole mobility of 14 to 42 carbon atoms.

[0304] The aromatic hydrocarbon may have a vinyl skeleton. Examples of aromatic hydrocarbons having a vinyl group include 4,4'-bis(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi) and 9,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene (abbreviation: DPVPA).

[0305] 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.

[0306] <Hole transport layer> The hole transport layer 112 is a layer containing a hole transport material, and can be made of any of the materials exemplified as the material for the hole injection layer 111. The hole transport layer 112 has a function of transporting holes injected into the hole injection layer 111 to the light-emitting layer 130, and therefore preferably has a HOMO level that is the same as or close to the HOMO level of the hole injection layer 111.

[0307] As the hole transport material, the materials exemplified as the material of the hole injection layer 111 can be used. -6 cm 2 It is preferable that the material has a hole mobility of 1 / Vs or more. However, other materials may be used as long as they have a higher hole transporting property than electron transporting property. Note that the layer containing the material with a high hole transporting property may be a single layer or may be a stack of two or more layers made of the above material.

[0308] ≪Electron transport layer≫ The electron transport layer 118 has a function of transporting electrons injected from the other of the pair of electrodes (the electrode 101 or the electrode 102) through the electron injection layer 119 to the light-emitting layer 130. As the electron-transporting material, a material having a higher electron transporting property than a hole transporting property can be used.-6 cm 2 It is preferable that the material has an electron mobility of 1×10 or more. As a compound that easily accepts electrons (a material having electron transport properties), a π-electron-deficient heteroaromatic compound such as a nitrogen-containing heteroaromatic compound, a metal complex, or the like can be used. Specific examples include metal complexes having a quinoline ligand, a benzoquinoline ligand, an oxazole ligand, or a thiazole ligand, which are listed as electron transport materials that can be used in the light-emitting layer 130. Other examples include oxadiazole derivatives, triazole derivatives, phenanthroline derivatives, pyridine derivatives, bipyridine derivatives, and pyrimidine derivatives. In addition, a compound having an electron mobility of 1×10 or more can be used. -6 cm 2 It is preferable that the electron-transport layer is a substance having an electron mobility of 1 / Vs or higher. Note that any substance other than the above may be used as the electron-transport layer as long as it has a higher electron-transporting property than hole-transporting property. The electron-transport layer 118 may be a single layer or a stack of two or more layers made of the above substances.

[0309] Furthermore, a layer for controlling the movement of electron carriers may be provided between the electron transport layer 118 and the light-emitting layer 130. The layer for controlling the movement of electron carriers is a layer in which a small amount of a substance with high electron trapping properties is added to a material with high electron transport properties as described above, and by suppressing the movement of electron carriers, it becomes possible to adjust the carrier balance. Such a configuration is highly effective in suppressing problems (e.g., a reduction in device life) caused by electrons penetrating the light-emitting layer.

[0310] ≪Electron injection layer≫ The electron injection layer 119 has a function of promoting electron injection by reducing the electron injection barrier from the electrode 102, and can be made of, for example, a Group 1 metal, a Group 2 metal, or an oxide, halide, or carbonate thereof. Also, a composite material of the above-mentioned electron transport material and a material that exhibits electron donating properties can be used. Examples of materials that exhibit electron donating properties include Group 1 metals, Group 2 metals, or oxides of these metals. Specific examples include lithium fluoride (LiF), sodium fluoride (NaF), cesium fluoride (CsF), calcium fluoride (CaF2), and lithium oxide (LiO x Alkali metals, alkaline earth metals, or compounds thereof such as fluorine-containing oxides (AlF3), etc. can be used. Rare earth metal compounds such as erbium fluoride (ErF3) can also be used. Electrides can also be used for the electron injection layer 119. Examples of such electrides include a substance in which a high concentration of electrons is added to a mixed oxide of calcium and aluminum. Materials that can be used for the electron transport layer 118 can also be used for the electron injection layer 119.

[0311] The electron injection layer 119 may also be made of a composite material obtained by mixing an organic compound and an electron donor (donor). Such a composite material has excellent electron injection and transport properties because electrons are generated in the organic compound by the electron donor. In this case, the organic compound is preferably a material that is excellent in transporting the generated electrons. Specifically, for example, the above-mentioned substances constituting the electron transport layer 118 (metal complexes, heteroaromatic compounds, etc.) can be used. The electron donor may be any substance that exhibits electron donating properties to the organic compound. Specifically, alkali metals, alkaline earth metals, and rare earth metals are preferred, such as lithium, cesium, magnesium, calcium, erbium, and ytterbium. Alkali metal oxides and alkaline earth metal oxides are preferred, such as lithium oxide, calcium oxide, and barium oxide. Lewis bases such as magnesium oxide can also be used. Organic compounds such as tetrathiafulvalene (abbreviated as TTF) can also be used.

[0312] The light-emitting layer, hole injection layer, hole transport layer, electron transport layer, and electron injection layer can be formed by vapor deposition (including vacuum deposition), inkjet printing, coating, nozzle printing, gravure printing, etc. In addition to the materials described above, the light-emitting layer, hole injection layer, hole transport layer, electron transport layer, and electron injection layer may also use inorganic compounds such as quantum dots or polymeric compounds (oligomers, dendrimers, polymers, etc.).

[0313] Quantum dots may be colloidal quantum dots, alloy quantum dots, core-shell quantum dots, core quantum dots, etc. Quantum dots containing elements from groups 2 and 16, 13 and 15, 13 and 17, 11 and 17, or 14 and 15 may also be used. Quantum dots containing elements such as cadmium (Cd), selenium (Se), zinc (Zn), sulfur (S), phosphorus (P), indium (In), tellurium (Te), lead (Pb), gallium (Ga), arsenic (As), and aluminum (Al) may also be used.

[0314] Examples of liquid media that can be used in wet processes include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, aromatic hydrocarbons such as toluene, xylene, mesitylene, and cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin, and dodecane, and organic solvents such as dimethylformamide (DMF) and dimethyl sulfoxide (DMSO).

[0315] Examples of polymer compounds that can be used in the light-emitting layer include polyphenylene vinylene (PPV) derivatives such as poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene] (abbreviation: MEH-PPV) and poly(2,5-dioctyl-1,4-phenylene vinylene), poly(9,9-di-n-octylfluorenyl-2,7-diyl) (abbreviation: PF8), poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazole-4,8-diyl)] (abbreviation: F8BT), poly[(9 ,9-di-n-octylfluorenyl-2,7-diyl)-alt-(2,2'-bithiophene-5,5'-diyl)] (abbreviated as F8T2), poly[(9,9-dioctyl-2,7-divinylenefluorenylene)-alt-(9,10-anthracene)], poly[(9,9-dihexylfluorene-2,7-diyl)-alt-(2,5-dimethyl-1,4-phenylene)], polyalkylthiophene (PAT) derivatives such as poly(3-hexylthiophene-2,5-diyl) (abbreviated as P3HT), and polyphenylene derivatives. Furthermore, these polymer compounds, as well as polymer compounds such as PVK, poly(2-vinylnaphthalene), and poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (abbreviation: PTAA), may be doped with a light-emitting compound and used in the light-emitting layer. As the light-emitting compound, the light-emitting compounds listed above can be used.

[0316] <Substrate> The light-emitting device according to one embodiment of the present invention may be fabricated over a substrate made of glass, plastic, or the like. The order of fabrication on the substrate may be from the electrode 101 side or from the electrode 102 side.

[0317] Note that, as a substrate on which a light-emitting device according to one embodiment of the present invention can be formed, for example, glass, quartz, or plastic can be used. A flexible substrate may also be used. A flexible substrate is a substrate that can be bent (flexible), and examples thereof include plastic substrates made of polycarbonate or polyarylate. Films, inorganic vapor-deposited films, and the like can also be used. Note that other materials may be used as long as they function as a support in the manufacturing process of the light-emitting device and the optical element. Alternatively, any material may be used as long as it has a function of protecting the light-emitting device and the optical element.

[0318] For example, in one embodiment of the present invention, a light-emitting device can be formed using various substrates. The type of substrate is not particularly limited. Examples of such substrates include semiconductor substrates (e.g., single-crystal substrates or silicon substrates), SOI substrates, glass substrates, quartz substrates, plastic substrates, metal substrates, stainless steel substrates, substrates with stainless steel foil, tungsten substrates, substrates with tungsten foil, flexible substrates, laminated films, cellulose nanofibers (CNF) containing fibrous materials, paper, and base films. Examples of glass substrates include barium borosilicate glass, aluminoborosilicate glass, and soda-lime glass. Examples of flexible substrates, laminated films, and base films include the following: Plastics such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), and polytetrafluoroethylene (PTFE). Other examples include resins such as acrylic. Other examples include polypropylene, polyester, polyvinyl fluoride, and polyvinyl chloride. Other examples include polyamide, polyimide, aramid, epoxy, inorganic vapor deposition film, and paper.

[0319] Alternatively, a flexible substrate may be used as the substrate, and the light-emitting device may be formed directly on the flexible substrate. Alternatively, a release layer may be provided between the substrate and the light-emitting device. The release layer can be used to separate the light-emitting device from the substrate after it has been partially or entirely completed and transfer it to another substrate. In this case, the light-emitting device can be transferred to a substrate with poor heat resistance or a flexible substrate. The release layer may be, for example, a laminated structure of inorganic films such as a tungsten film and a silicon oxide film, or a structure in which a resin film such as polyimide is formed on a substrate.

[0320] That is, a light-emitting device may be formed using a certain substrate, and then the light-emitting device may be transferred to another substrate, and the light-emitting device may be disposed on the other substrate. In addition to the substrates mentioned above, examples of the substrate onto which the light-emitting device may be transferred include a cellophane substrate, a stone substrate, a wood substrate, a cloth substrate (including natural fibers (silk, cotton, linen), synthetic fibers (nylon, polyurethane, polyester), or recycled fibers (acetate, cupra, rayon, recycled polyester)), a leather substrate, or a rubber substrate. By using these substrates, a light-emitting device that is durable, highly heat-resistant, lightweight, or thin can be obtained.

[0321] Alternatively, for example, a field effect transistor (FET) may be formed on the substrate described above, and the light emitting device 150 may be fabricated on an electrode electrically connected to the FET. This makes it possible to fabricate an active matrix display device in which the FET controls the driving of the light emitting device.

[0322] The structure described in this embodiment mode can be used in appropriate combination with other embodiment modes.

[0323] (Embodiment 3) In this embodiment, a light-emitting device having a different configuration from that of the light-emitting device shown in embodiment 1 will be described below with reference to Fig. 7. In Fig. 7, parts having the same functions as those shown in Fig. 1A may be indicated with the same hatched pattern and the reference numerals may be omitted. Parts having the same functions may be indicated with the same reference numerals and detailed descriptions thereof may be omitted.

[0324] <Light-emitting device configuration example 2> FIG. 7 is a schematic cross-sectional view of a light-emitting device 250. As shown in FIG.

[0325] The light-emitting device 250 shown in FIG. 7 has a plurality of light-emitting units (light-emitting unit 106 and light-emitting unit 108) between a pair of electrodes (electrode 101 and electrode 102). It is preferable that any one of the plurality of light-emitting units has a configuration similar to that of the EL layer 100 shown in FIG. 1A. In other words, it is preferable that the light-emitting device 150 shown in FIG. 1A has one light-emitting unit, and the light-emitting device 250 has a plurality of light-emitting units. Note that, in the light-emitting device 250, the electrode 101 functions as an anode and the electrode 102 functions as a cathode, but the configuration of the light-emitting device 250 may be reversed.

[0326] 7, the light-emitting unit 106 and the light-emitting unit 108 are stacked, and a charge generation layer 115 is provided between the light-emitting unit 106 and the light-emitting unit 108. The light-emitting unit 106 and the light-emitting unit 108 may have the same structure or different structures. For example, it is preferable that the light-emitting unit 108 has the same structure as the EL layer 100.

[0327] Light-emitting device 250 also includes light-emitting layer 120 and light-emitting layer 170. Light-emitting unit 106 also includes, in addition to light-emitting layer 120, hole injection layer 111, hole transport layer 112, electron transport layer 113, and electron injection layer 114. Light-emitting unit 108 also includes, in addition to light-emitting layer 170, hole injection layer 116, hole transport layer 117, electron transport layer 118, and electron injection layer 119.

[0328] The light-emitting device 250 may contain a compound according to one embodiment of the present invention in any layer of the light-emitting unit 106 or the light-emitting unit 108. The layer containing the compound is preferably the light-emitting layer 120 or the light-emitting layer 170.

[0329] The charge generation layer 115 may be a structure in which an acceptor substance that is an electron acceptor is added to a hole transporting material, or a structure in which a donor substance that is an electron donor is added to an electron transporting material, or a structure in which both of these structures are laminated.

[0330] When the charge generation layer 115 contains a composite material of an organic compound and an acceptor substance, the composite material that can be used for the hole injection layer 111 described in Embodiment 1 may be used. As the organic compound, various compounds such as aromatic amine compounds, carbazole compounds, aromatic hydrocarbons, and polymer compounds (oligomers, dendrimers, polymers, etc.) can be used. Note that the organic compound is an organic compound having a hole mobility of 1×10 -6 cm 2 It is preferable to use a material having a conductivity of 1 / Vs or higher. However, other materials may be used as long as they have a higher hole transporting property than electron transporting property. Composite materials of organic compounds and acceptor substances have excellent carrier injection and carrier transporting properties, and therefore can achieve low-voltage drive and low-current drive. Note that when the anode-side surface of the light-emitting unit is in contact with the charge-generation layer 115, the charge-generation layer 115 can also function as a hole-injection layer or hole-transport layer of the light-emitting unit, so the light-emitting unit may not have a hole-injection layer or hole-transport layer. Alternatively, when the cathode-side surface of the light-emitting unit is in contact with the charge-generation layer 115, the charge-generation layer 115 can also function as an electron-injection layer or electron-transport layer of the light-emitting unit, so the light-emitting unit may not have an electron-injection layer or electron-transport layer.

[0331] The charge generation layer 115 may be formed as a stacked layer including a layer containing a composite material of an organic compound and an acceptor substance and a layer containing another material. For example, the charge generation layer 115 may be formed by combining a layer containing a composite material of an organic compound and an acceptor substance with a layer containing a compound selected from electron donor substances and a compound with high electron transport properties. Alternatively, the charge generation layer 115 may be formed by combining a layer containing a composite material of an organic compound and an acceptor substance with a layer containing a transparent conductive film.

[0332] Charge generation layer 115 sandwiched between light-emitting unit 106 and light-emitting unit 108 may be any layer that injects electrons into one light-emitting unit and injects holes into the other light-emitting unit when a voltage is applied between electrode 101 and electrode 102. For example, in FIG. 7, when a voltage is applied so that the potential of electrode 101 is higher than the potential of electrode 102, charge generation layer 115 injects electrons into light-emitting unit 106 and injects holes into light-emitting unit 108.

[0333] From the viewpoint of light extraction efficiency, the charge generation layer 115 preferably has transparency to visible light (specifically, the visible light transmittance of the charge generation layer 115 is 40% or more). Furthermore, the charge generation layer 115 functions even if it has lower conductivity than the pair of electrodes (electrodes 101 and 102).

[0334] By forming the charge generating layer 115 using the above-mentioned materials, it is possible to suppress an increase in driving voltage when a light emitting layer is laminated.

[0335] 7 illustrates a light-emitting device having two light-emitting units, but the present invention can be applied to a light-emitting device having three or more stacked light-emitting units. As shown in light-emitting device 250, by arranging multiple light-emitting units between a pair of electrodes and separating them with a charge-generating layer, a light-emitting device can be realized that emits high-intensity light while maintaining a low current density and has a long life. Furthermore, a light-emitting device with low power consumption can be realized.

[0336] In each of the above configurations, the guest materials used in the light-emitting units 106 and 108 may emit light of the same or different colors. When the light-emitting units 106 and 108 contain guest materials capable of emitting light of the same color, the light-emitting device 250 preferably exhibits high luminance at a low current. Furthermore, when the light-emitting units 106 and 108 contain guest materials capable of emitting light of different colors, the light-emitting device 250 preferably exhibits multicolor emission. In this case, by using multiple light-emitting materials with different emission wavelengths in either or both of the light-emitting layers 120 and 170, the light-emitting device 250 emits light that has different emission peaks, resulting in an emission spectrum with at least two maxima.

[0337] The above configuration is also suitable for obtaining white light emission. White light emission can be obtained by making the light from the light-emitting layer 120 and the light-emitting layer 170 complementary to each other. In particular, it is preferable to select a guest material that will produce white light emission with high color rendering properties or light emission having at least red, green, and blue.

[0338] It is preferable to use the configuration of the light-emitting layer 130 shown in Embodiment 1 for one or both of the light-emitting layer 120 and the light-emitting layer 170. By using such a configuration, a light-emitting device with good luminous efficiency and reliability can be obtained. The guest material contained in the light-emitting layer 130 is a fluorescent material. Therefore, by using the configuration of the light-emitting layer 130 shown in Embodiment 1 for one or both of the light-emitting layer 120 and the light-emitting layer 170, a light-emitting device with high efficiency and high reliability can be obtained.

[0339] Furthermore, in a light-emitting device having three or more stacked light-emitting units, the guest materials used in each light-emitting unit may emit light of the same or different colors. When multiple light-emitting units emit light of the same color, the emitted light from these multiple light-emitting units can achieve high luminance at a small current value. This configuration is suitable for adjusting the emitted color. This is particularly suitable when guest materials with different luminous efficiencies and different emitted colors are used. For example, in a light-emitting device having three layers of light-emitting units, two layers of light-emitting units each having a fluorescent material of the same color and one layer of light-emitting unit each having a phosphorescent material that emits light of a different color from the fluorescent material can adjust the intensity of the fluorescent and phosphorescent emissions. In other words, the intensity of the emitted color can be adjusted by changing the number of light-emitting units.

[0340] In the case of such a light-emitting device having two fluorescent-emitting units and one phosphorescent-emitting unit, a light-emitting device having two light-emitting units containing a blue fluorescent material and one light-emitting unit containing a yellow phosphorescent material, a light-emitting device having two light-emitting units containing a blue fluorescent material and one light-emitting unit containing a red phosphorescent material and a green phosphorescent material, or a light-emitting device having two light-emitting units containing a blue fluorescent material and one light-emitting unit containing a red phosphorescent material, a yellow phosphorescent material, and a green phosphorescent material is preferable because white light can be efficiently emitted. In this way, the light-emitting device of one embodiment of the present invention can be appropriately combined with a phosphorescent light-emitting unit.

[0341] Furthermore, the above-described phosphorescent light-emitting unit emits light of a color other than blue. The light-emitting unit other than blue can have the same configuration as the light-emitting layer 130 described in embodiment 1. In this case, the light-emitting unit other than blue contains a fluorescent material. For example, a light-emitting device containing two light-emitting units containing a blue fluorescent material and one light-emitting unit containing a yellow fluorescent material, a light-emitting device containing two light-emitting units containing a blue fluorescent material and one light-emitting unit containing a red fluorescent material and a green fluorescent material, or a light-emitting device containing two light-emitting units containing a blue fluorescent material and one light-emitting unit containing a red fluorescent material, a yellow fluorescent material, and a green fluorescent material can be considered. In this case, the light-emitting device may also use the light-emitting layer 130 described in embodiment 1 for light-emitting units that emit light of a color other than blue, or for the red, green, and yellow light-emitting units in the case of a combination of the above-described light-emitting units. This configuration is preferable because it efficiently produces white light. In this case, the light-emitting layer of the blue fluorescent light-emitting unit may contain the following materials. Furthermore, the relationship between the T1 level of the host material and the T1 level of the guest material contained in the light-emitting layer of the blue fluorescent light-emitting unit is preferably such that the T1 level of the host material is lower than the T1 level of the guest material, since this is expected to result in high efficiency due to triplet-triplet annihilation (TTA). Of course, the blue fluorescent light-emitting unit may also have the configuration of the light-emitting layer 130 shown in embodiment 1.

[0342] Alternatively, at least one of the light-emitting layers 120 and 170 may be further divided into layers, with each divided layer containing a different light-emitting material. That is, at least one of the light-emitting layers 120 and 170 may be composed of two or more layers. For example, when a first light-emitting layer and a second light-emitting layer are stacked in order from the hole-transport layer side to form a light-emitting layer, a material having hole-transport properties may be used as the host material for the first light-emitting layer, and a material having electron-transport properties may be used as the host material for the second light-emitting layer. In this case, the light-emitting materials contained in the first and second light-emitting layers may be the same or different, and may be materials capable of emitting light of the same color or different colors. By using multiple light-emitting materials capable of emitting light of different colors, it is possible to obtain white light with high color rendering, consisting of three primary colors or four or more emitting colors.

[0343] Note that this embodiment mode can be combined with other embodiment modes as appropriate.

[0344] (Fourth embodiment) In this embodiment mode, a light-emitting device using the light-emitting devices described in Embodiment Modes 1 and 3 will be described with reference to FIGS. 8A and 8B. FIG.

[0345] Figure 8A is a top view showing the light-emitting device, and Figure 8B is a cross-sectional view taken along lines AB and CD in Figure 8A. This light-emitting device includes a drive circuit section (source-side drive circuit) 601, a pixel section 602, and a drive circuit section (gate-side drive circuit) 603, all of which are shown by dotted lines to control the light emission of the light-emitting device. Also, 604 is a sealing substrate, 625 is a desiccant, and 605 is a sealant, with space 607 defined inside the sealant 605.

[0346] The routing wiring 608 is wiring for transmitting signals input to the source side driver circuit 601 and the gate side driver circuit 603, and receives video signals, clock signals, start signals, reset signals, etc. from an FPC (flexible printed circuit) 609, which serves as an external input terminal. Although only an FPC is shown here, a printed wiring board (PWB) may 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.

[0347] Next, the cross-sectional structure of the light-emitting device will be described with reference to Fig. 8B. A driver circuit section and a pixel section are formed on an element substrate 610, and here, a source-side driver circuit 601, which is the driver circuit section, and one pixel in a pixel section 602 are shown.

[0348] The source side driver circuit 601 is formed as a CMOS circuit that combines an n-channel TFT 623 and a p-channel TFT 624. The driver circuit may be formed of various CMOS circuits, PMOS circuits, etc. In this embodiment, a driver-integrated type in which the driver circuit is formed on the substrate is shown, but this is not necessarily required, and the driver circuit may also be formed externally rather than on the substrate.

[0349] The pixel section 602 is formed by pixels including a switching TFT 611, a current control TFT 612, and a first electrode 613 electrically connected to the drain of the TFT 612. An insulator 614 is formed to cover the end of the first electrode 613. The insulator 614 can be formed by using a positive photosensitive resin film.

[0350] Furthermore, in order to improve the coverage of the film formed on the insulator 614, a curved surface is formed at the upper or lower end of the insulator 614. For example, when photosensitive acrylic is used as the material for the insulator 614, it is preferable to provide a curved surface only at the upper end of the insulator 614. The radius of curvature of the curved surface is preferably 0.2 μm or more and 0.3 μm or less. Furthermore, either a negative or positive photosensitive material can be used for the insulator 614.

[0351] An EL layer 616 and a second electrode 617 are formed on the first electrode 613. The first electrode 613, which functions as an anode, is preferably made of a material with a large work function. For example, a single-layer film such as an ITO film, an indium tin oxide film containing silicon, an indium oxide film containing 2 wt % to 20 wt % of zinc oxide, a titanium nitride film, a chromium film, a tungsten film, a Zn film, or a Pt film can be used. Other examples include a laminated structure of a film mainly composed of titanium nitride and aluminum, and a three-layer structure of a titanium nitride film, a film mainly composed of aluminum, and another titanium nitride film. The laminated structure provides low wiring resistance, good ohmic contact, and the first electrode 613 can function as an anode.

[0352] The EL layer 616 can be formed by various methods such as a vapor deposition method using a vapor deposition mask, an inkjet method, a spin coating method, etc. The material constituting the EL layer 616 may be a low molecular weight compound or a high molecular weight compound (including an oligomer or a dendrimer).

[0353] Furthermore, the second electrode 617, which is formed on the EL layer 616 and functions as a cathode, is preferably made of a material with a small work function (Al, Mg, Li, Ca, or alloys or compounds thereof, such as MgAg, MgIn, and AlLi). When light generated in the EL layer 616 is to be transmitted through the second electrode 617, the second electrode 617 is preferably made of a laminate of a thin metal thin film and a transparent conductive film (ITO, indium oxide containing 2 wt % to 20 wt % zinc oxide, indium tin oxide containing silicon, zinc oxide (ZnO), or the like).

[0354] Note that a light-emitting device 618 is formed by the first electrode 613, the EL layer 616, and the second electrode 617. The light-emitting device 618 is preferably a light-emitting device having the structures described in Embodiments 1 and 2. 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 a light-emitting device having the structure described in Embodiment 2 and a light-emitting device having another structure.

[0355] 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 an inert gas (nitrogen, argon, etc.), or may be filled with a resin, a desiccant, or both.

[0356] 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, etc. can be used for the sealing substrate 604.

[0357] In this manner, a light emitting apparatus using the light emitting device described in the second embodiment can be obtained.

[0358] <Configuration example 1 of light-emitting device> FIG. 9 shows an example of a light-emitting device in which a light-emitting device that emits white light is formed and a colored layer (color filter) is formed.

[0359] Figure 9A shows a substrate 1001, a base insulating film 1002, a gate insulating film 1003, gate electrodes 1006, 1007, 1008, a first interlayer insulating film 1020, a second interlayer insulating film 1021, a peripheral section 1042, a pixel section 1040, a driving circuit section 1041, first electrodes 1024W, 1024R, 1024G, 1024B of the light-emitting device, a partition wall 1026, an EL layer 1028, a second electrode 1029 of the light-emitting device, a sealing substrate 1031, a sealant 1032, a red pixel 1044R, a green pixel 1044G, a blue pixel 1044B, and a white pixel 1044W.

[0360] 9A and 9B, colored layers (a red colored layer 1034R, a green colored layer 1034G, and a blue colored layer 1034B) are provided on a transparent base material 1033. A black layer (black matrix) 1035 may also be provided. The transparent base material 1033 on which the colored layers and black layers are provided is aligned and fixed to the substrate 1001. The colored layers and black layer are covered with an overcoat layer 1036. Also, in FIG. 9A, 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, blue, and green, so that an image can be displayed using four color pixels.

[0361] 9B shows an example in which a red colored layer 1034R, a green colored layer 1034G, and a blue colored layer 1034B are formed between the gate insulating film 1003 and the first interlayer insulating film 1020. As shown in FIG. 9B, the colored layers may be provided between the substrate 1001 and the sealing substrate 1031.

[0362] Furthermore, the light-emitting device described above is a light-emitting device having a structure in which light is extracted from the substrate 1001 side on which the TFT is formed (bottom emission type), but it may also be a light-emitting device having a structure in which light is extracted from the sealing substrate 1031 side (top emission type).

[0363] <Configuration Example 2 of Light-Emitting Device> Cross-sectional views of a top-emission light-emitting device are shown in Figures 10A and 10B. In this case, a substrate that does not transmit light can be used as the substrate 1001. The process is the same as for a bottom-emission light-emitting device until a connection electrode that connects the TFT and the anode of the light-emitting device is formed. 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 1021, as well as various other materials.

[0364] The lower electrodes 1025W, 1025R, 1025G, and 1025B of the light-emitting device are herein anodes, but may be cathodes. In addition, in the case of a top-emission light-emitting device such as that shown in FIGS. 10A and 10B, the lower electrodes 1025W, 1025R, 1025G, and 1025B are preferably reflective electrodes. The second electrode 1029 preferably has the function of reflecting and transmitting light. Furthermore, a microcavity structure is preferably applied between the second electrode 1029 and the lower electrodes 1025W, 1025R, 1025G, and 1025B to amplify light of a specific wavelength. The EL layer 1028 is configured as described in Embodiments 1 and 3, and has an element structure that produces white light.

[0365] 9A, 9B, 10A, and 10B, the EL layer configuration that can provide white light emission can be achieved by using multiple light-emitting layers, multiple light-emitting units, etc. However, the configuration that can provide white light emission is not limited to these.

[0366] In the top emission structure shown in FIGS. 10A and 10B, sealing can be performed using a sealing substrate 1031 provided with colored layers (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B). The sealing substrate 1031 may be provided with a black layer (black matrix) 1030 positioned between pixels. The colored layers (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B) may be covered with an overcoat layer. Note that a light-transmitting substrate is used as the sealing substrate 1031.

[0367] 10A shows a configuration for full-color display using three colors, red, green, and blue, but as shown in FIG. 10B, full-color display using four colors, red, green, blue, and white, may also be performed. The configuration for full-color display is not limited to this. For example, full-color display using four colors, red, green, blue, and yellow, may also be performed.

[0368] A light-emitting device according to one embodiment of the present invention uses a fluorescent material as a guest material. Compared to phosphorescent materials, fluorescent materials have a sharper spectrum and therefore can emit light with high color purity. Therefore, by using the light-emitting device in the light-emitting device described in this embodiment, a light-emitting device with high color reproducibility can be obtained.

[0369] In this manner, a light emitting apparatus using the light emitting device described in the second embodiment can be obtained.

[0370] Note that this embodiment mode can be combined with other embodiment modes as appropriate.

[0371] (Embodiment 5) In this embodiment, an electronic device and a display device according to one embodiment of the present invention will be described.

[0372] According to one embodiment of the present invention, highly reliable electronic devices and display devices having flat surfaces and high emission efficiency can be manufactured. Furthermore, according to one embodiment of the present invention, highly reliable electronic devices and display devices having curved surfaces and high emission efficiency can be manufactured. Furthermore, a light-emitting device with high color reproducibility can be obtained.

[0373] Examples of electronic devices include television sets, desktop or notebook personal computers, computer monitors, digital cameras, digital video cameras, digital photo frames, mobile phones, portable game consoles, personal digital assistants, sound players, and large game machines such as pachinko machines.

[0374] A mobile information terminal 900 shown in FIGS. 11A and 11B includes a housing 901, a housing 902, a display portion 903, a hinge portion 905, and the like.

[0375] Housings 901 and 902 are connected by hinge portion 905. Portable information terminal 900 can be unfolded from a folded state (FIG. 11A) to the state shown in FIG. 11B. This allows for excellent portability when carried around, and excellent visibility due to the large display area when in use.

[0376] The portable information terminal 900 has a flexible display unit 903 that spans a housing 901 and a housing 902 that are connected by a hinge unit 905 .

[0377] A light-emitting device manufactured according to one embodiment of the present invention can be used for the display portion 903. This enables the manufacture of a highly reliable portable information terminal.

[0378] The display unit 903 can display at least one of document information, still images, and moving images, etc. When document information is displayed on the display unit, the portable information terminal 900 can be used as an electronic book terminal.

[0379] When the mobile information terminal 900 is unfolded, the display portion 903 is held in a state where the radius of curvature is large. For example, the display portion 903 is held including a curved portion with a radius of curvature of 1 mm to 50 mm, preferably 5 mm to 30 mm. In part of the display portion 903, pixels are continuously arranged from the housing 901 to the housing 902, enabling curved display.

[0380] The display unit 903 functions as a touch panel and can be operated with a finger, a stylus, or the like.

[0381] The display unit 903 is preferably configured as a single flexible display, which allows continuous display without interruption between the housing 901 and the housing 902. Note that a display may be provided on each of the housings 901 and 902.

[0382] Hinge unit 905 preferably has a locking mechanism so that the angle between housing 901 and housing 902 does not exceed a predetermined angle when mobile information terminal 900 is unfolded. For example, the angle at which the locking occurs (the device does not open any further) is preferably equal to or greater than 90 degrees and less than 180 degrees, and can typically be 90 degrees, 120 degrees, 135 degrees, 150 degrees, or 175 degrees. This can improve the convenience, safety, and reliability of mobile information terminal 900.

[0383] If the hinge section 905 has a locking mechanism, excessive force will not be applied to the display section 903, and damage to the display section 903 can be prevented. Therefore, a highly reliable mobile information terminal can be realized.

[0384] The housing 901 and the housing 902 may each include a power button, operation buttons, an external connection port, a speaker, a microphone, and the like.

[0385] Either the housing 901 or the housing 902 is provided with a wireless communication module, which makes it possible to send and receive data via a computer network such as the Internet, a LAN (Local Area Network), or Wi-Fi (registered trademark).

[0386] A mobile information terminal 910 shown in FIG. 11C includes a housing 911, a display unit 912, operation buttons 913, an external connection port 914, a speaker 915, a microphone 916, a camera 917, and the like.

[0387] A light-emitting device manufactured using one embodiment of the present invention can be used for the display portion 912. This enables the portable information terminal to be manufactured with a high yield.

[0388] The mobile information terminal 910 has a touch sensor on the display unit 912. Any operation, such as making a call or inputting characters, can be performed by touching the display unit 912 with a finger or a stylus.

[0389] Furthermore, by operating the operation button 913, it is possible to turn the power on and off and to switch the type of image displayed on the display unit 912. For example, it is possible to switch from an email creation screen to a main menu screen.

[0390] Furthermore, by providing a detection device such as a gyro sensor or an acceleration sensor inside the mobile information terminal 910, it is possible to determine the orientation (portrait or landscape) of the mobile information terminal 910 and automatically switch the orientation of the screen display on the display unit 912. The orientation of the screen display can also be switched by touching the display unit 912, operating the operation button 913, or by voice input using the microphone 916.

[0391] The mobile information terminal 910 has one or more functions selected from, for example, a telephone, a notebook, an information viewing device, etc. Specifically, it can be used as a smartphone. The mobile information terminal 910 can execute various applications, such as mobile phone, e-mail, document viewing and creation, music playback, video playback, internet communication, and games.

[0392] 11D includes a housing 921, a display unit 922, operation buttons 923, a shutter button 924, etc. Furthermore, the camera 920 is equipped with a detachable lens 926.

[0393] A light-emitting device manufactured using one embodiment of the present invention can be used for the display portion 922. This makes it possible to manufacture a highly reliable camera.

[0394] Here, camera 920 is configured such that lens 926 can be detached from housing 921 and replaced, but lens 926 and housing 921 may be integrated.

[0395] The camera 920 can capture still images or moving images by pressing a shutter button 924. The display unit 922 also functions as a touch panel, and an image can also be captured by touching the display unit 922.

[0396] The camera 920 may be equipped with a strobe device, a viewfinder, and the like, or these may be incorporated into the housing 921.

[0397] FIG. 12A is a schematic diagram showing an example of a cleaning robot.

[0398] 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.

[0399] 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.

[0400] 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.

[0401] 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.

[0402] 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 5140 such as a smartphone.

[0403] The light-emitting device according to one embodiment of the present invention can be used for the display 5101 .

[0404] The robot 2100 shown in FIG. 12B 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.

[0405] 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.

[0406] 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.

[0407] The upper camera 2103 and the lower camera 2106 have the function of capturing images of the surroundings of the robot 2100. Furthermore, the obstacle sensor 2107 can detect the presence or absence of obstacles in the direction of travel when the robot 2100 moves forward using the movement 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.

[0408] The light-emitting device according to one embodiment of the present invention can be used for the display 2105 .

[0409] 12C 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 ray), a microphone 5008, a second display unit 5002, a support unit 5012, and earphones 5013.

[0410] The light-emitting device of one embodiment of the present invention can be used for the display portion 5001 and the second display portion 5002 .

[0411] 13A and 13B 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. 13A shows the mobile information terminal 5150 in an unfolded state. FIG. 13B shows the mobile information terminal 5150 in a folded state. Despite having a large display area 5152, the mobile information terminal 5150 is compact and highly portable when folded.

[0412] Display area 5152 can be folded in half by bending portion 5153. Bending portion 5153 is composed of an expandable member and multiple support members, and when folding, the expandable member stretches and bending portion 5153 is folded with a curvature radius of 2 mm or more, preferably 5 mm or more.

[0413] 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.

[0414] This embodiment mode can be combined with other embodiment modes as appropriate.

[0415] (Sixth embodiment) In this embodiment, an example in which the light-emitting device of one embodiment of the present invention is applied to various lighting devices will be described with reference to Fig. 14. By using the light-emitting device of one embodiment of the present invention, a lighting device with high emission efficiency and high reliability can be manufactured.

[0416] By manufacturing the light-emitting device of one embodiment of the present invention over a flexible substrate, electronic devices and lighting devices each having a light-emitting region with a curved surface can be realized.

[0417] Furthermore, a light-emitting device to which the light-emitting device of one embodiment of the present invention is applied can also be used for lighting in automobiles, and for example, lighting can be installed on the windshield, ceiling, or the like.

[0418] FIG. 14 shows an example in which the light-emitting device is used as an indoor lighting device 8501. Note that the light-emitting device can be made large, so a large-area lighting device can also be formed. Alternatively, by using a housing with a curved surface, a lighting device 8502 with a curved light-emitting region can also be formed. The light-emitting device shown in this embodiment mode is a thin film, and the housing has a high degree of freedom in design. Therefore, lighting devices with various elaborate designs can be formed. Furthermore, a large lighting device 8503 may be provided on a wall surface in a room. A touch sensor may be provided in the lighting devices 8501, 8502, and 8503 to turn the power on or off.

[0419] Furthermore, by using the light-emitting device on the surface side of a table, the lighting device 8504 can function as a table. Note that by using the light-emitting device in part of other furniture, the lighting device can function as furniture.

[0420] In this manner, a lighting device and an electronic device can be obtained by applying the light-emitting device of one embodiment of the present invention. Note that applicable lighting devices and electronic devices are not limited to those described in this embodiment, and lighting devices and electronic devices in various fields can be used.

[0421] The structure described in this embodiment mode can be used in appropriate combination with structures described in other embodiments. [Example]

[0422] <Synthesis Example 1> This example describes a synthesis method for 5,12-bis(2,4,6-tricyclohexylphenyl)-5,12-dihydroquino[2,3-b]acridine-7,14-dione (abbreviation: ch3P2Qd), which is an organic compound represented by structural formula (100) in Embodiment 1. The structural formula of ch3P2Qd is shown below.

[0423] [ka]

[0424] <Step 1: Synthesis of dimethyl 2,5-dihydro-3,6-bis(phenylamino)terephthalate> 20 g (88 mmol) of dimethyl 1,4-cyclohexanedione-2,5-dicarboxylate and 26 g (280 mmol) of aniline were placed in a 500 mL three-neck flask and the mixture was heated at 80 °C for 5 hours. The precipitated solid was collected by suction filtration and washed with hexane and methanol, yielding 33 g of a mixture of the target product and its oxidized form. This mixture was used directly in Step 2. The synthesis scheme for Step 1 is shown below.

[0425] [ka]

[0426] <Step 2: Synthesis of dimethyl 2,5-bis(phenylamino)terephthalate> The mixture of 33 g of dimethyl 2,5-dihydro-3,6-bis(phenylamino)terephthalate and its oxide obtained in Step 1, 10 g of iodine, and 220 mL of toluene was placed in a 500 mL three-neck flask equipped with a reflux condenser and refluxed at 120 °C for 16 hours. After stirring, water was added to the resulting mixture, and the aqueous layer was extracted with toluene. The resulting organic layer was washed with water, aqueous sodium thiosulfate, and saturated brine, and then dried over magnesium sulfate. The magnesium sulfate was removed from the resulting mixture by gravity filtration, and the resulting filtrate was concentrated to yield 20 g of a red solid. This solid was recrystallized from ethanol and acetone to yield 13 g of the desired red solid in a 40% yield. The synthesis scheme for Step 2 is shown below.

[0427] [ka]

[0428] <Step 3: Synthesis of dimethyl 2,5-bis[(2,4,6-tricyclohexylphenyl)phenylamino]terephthalate> 1.7 g (4.5 mmol) of dimethyl 2,5-bis(phenylamino)terephthalate obtained in Step 2, 4.0 g (10 mmol) of 1-bromo-2,4,6-tricyclohexylbenzene, 0.57 g (9.0 mmol) of copper, 0.86 g (4.5 mmol) of copper iodide, 1.4 g (10 mmol) of potassium carbonate, and 5 mL of diphenyl ether were placed in a 200 mL three-neck flask equipped with a reflux condenser. The mixture was degassed under reduced pressure and then purged with nitrogen. The mixture was stirred at 235 °C for 11 hours. Toluene and water were added to the resulting mixture, which was then suction filtered to remove insoluble matter. The resulting filtrate was separated into an organic layer and an aqueous layer. The organic layer was washed with water and saturated brine and dried over magnesium sulfate. The magnesium sulfate was removed from the resulting mixture by gravity filtration, and the resulting filtrate was concentrated to yield a dark brown viscous solid. The resulting solid was purified by silica gel chromatography (eluent: hexane:toluene = 1:1) to obtain 0.58 g of an orange-yellow solid in a yield of 13%. LC\MS analysis of the resulting orange-yellow solid revealed that it had an m / z of 1021.68, confirming that it was the target compound. The synthesis scheme for Step 3 is shown below.

[0429] [ka]

[0430] <Step 4: Synthesis of 5,12-bis(2,4,6-tricyclohexylphenyl)-5,12-dihydroquino[2,3-b]acridine-7,14-dione (abbreviation: ch3P2Qd)> 0.58 g of dimethyl 2,5-bis[N,N'-(2,4,6-tricyclohexylphenyl)phenylamino]terephthalate obtained in Step 3 and 5 mL of methanesulfonic acid were placed in a 100 mL three-neck flask and stirred at 140 °C for 1.5 hours. After cooling, the reaction mixture was quenched by adding ice water. Toluene was added to the resulting mixture, and the aqueous layer was extracted. The resulting organic layer was washed with water and subsequently neutralized with saturated aqueous sodium bicarbonate. The organic layer was washed with saturated brine and dried over magnesium sulfate. The magnesium sulfate was removed from the resulting mixture by gravity filtration, and the filtrate was concentrated to yield 0.49 g of an orange-yellow solid. The resulting solid was washed twice with acetone and a small amount of toluene, and then dried to yield 0.32 g of an orange-yellow solid in 59% yield. The scheme for Step 4 is shown below.

[0431] [ka]

[0432] 0.22 g of the orange-yellow solid obtained in Step 4 was purified by train sublimation. The sublimation purification was carried out by heating the solid at 320 °C under a pressure of 3.4 Pa for 8 hours while flowing argon at 5 mL / min. After sublimation purification, 0.15 g of the target orange-yellow solid was obtained with a recovery rate of 68%.

[0433] The obtained solid 1 The H NMR charts are shown in Figures 15A and 15B, and the numerical data are shown below. This indicates that the target compound was obtained. 1 H NMR (dichloromethane-d2,300MHz): δ=8.42(dd,J=8.1Hz,1.5Hz,2H),7.90(s,2H),7.50(t,J=8.1Hz,2H),7.34(s,4H),7.22( t,J=7.5Hz,2H),6.71(d,J=8.4Hz,2H),2.78-2.70(m,2H),2.13-1.26(m,52H),1.11-1.03(m,4H),0.76-0.61(m,8H)

[0434] Next, the UV-visible absorption spectrum (hereinafter simply referred to as "absorption spectrum"), emission spectrum, and emission quantum yield of a dichloromethane solution of ch3P2Qd were measured. The absorption spectrum was measured using a UV-visible spectrophotometer (JASCO Corporation, V-550). The absorption spectrum of the solution was calculated by subtracting the absorption spectrum measured with only dichloromethane in a quartz cell. The emission spectrum was measured using a fluorometer (JASCO Corporation, FP-8600). The quantum yield was measured using an absolute PL quantum yield measurement device (Hamamatsu Photonics, Quantaurus-QY).

[0435] The measurement results of the absorption spectrum and emission spectrum of the obtained dichloromethane solution are shown in Figure 16. The horizontal axis represents wavelength, and the vertical axis represents absorption intensity and emission intensity. The horizontal axis represents wavelength, and the vertical axis represents absorption intensity and emission intensity. From the results in Figure 16, the dichloromethane solution of ch3P2Qd exhibited absorption peaks near 515 nm, 482 nm, and 456 nm, and emission wavelength peaks at 617 nm, 565 nm, and 528 nm (excitation wavelength: 480 nm). In addition, when the quantum yield of the dichloromethane solution was measured, it was found to be very high at 94%, indicating that ch3P2Qd is suitable as a light-emitting material.

[0436] The HOMO and LUMO levels of ch3P2Qd were calculated based on cyclic voltammetry (CV) measurements. An electrochemical analyzer (BAS Corporation, Model ALS Model 600A or 600C) was used. The solution used for CV measurements was prepared by dissolving the supporting electrolyte tetra-n-butylammonium perchlorate (n-Bu4NClO4) (Tokyo Chemical Industry Co., Ltd., Catalog No. T0836) at a concentration of 100 mmol / L in dehydrated dimethylformamide (DMF) (Aldrich Corporation, 99.8%, Catalog No. 22705-6) and further dissolving the target compound at a concentration of 2 mmol / L. The working electrode was a platinum electrode (PTE platinum electrode, manufactured by BAS Co., Ltd.), the auxiliary electrode was a platinum electrode (Pt counter electrode (5 cm) for VC-3, manufactured by BAS Co., Ltd.), and the reference electrode was an Ag / Ag electrode (RE7 non-aqueous solvent reference electrode, manufactured by BAS Co., Ltd.). The measurements were carried out at room temperature (20 to 25°C). The scan rate during CV measurement was standardized to 0.1 V / sec, and the oxidation potential Ea [V] and reduction potential Ec [V] relative to the reference electrode were measured. Ea was the midpoint potential of the oxidation-reduction wave, and Ec was the midpoint potential of the reduction-oxidation wave. Here, since the potential energy of the reference electrode used in this example relative to the vacuum level is known to be -4.94 [eV], the HOMO level and LUMO level can be calculated from the formulas HOMO level [eV] = -4.94 - Ea and LUMO level [eV] = -4.94 - Ec, respectively.

[0437] In addition, the CV measurement was repeated 100 times, and the oxidation-reduction wave in the 100th cycle measurement was compared with the oxidation-reduction wave in the first cycle to examine the electrical stability of the compound. As a result, the HOMO level of ch3P2Qd was found to be -5.78 eV in the measurement of the oxidation potential Ea [V]. On the other hand, the LUMO level of ch3P2Qd was found to be -3.24 eV in the measurement of the reduction potential Ec [V]. Furthermore, when the waveforms after the first and 100th cycles of repeated measurements of the oxidation-reduction wave were compared, 84% of the peak intensity was maintained in the Ec measurement.

[0438] Differential thermal analysis (DTA) of ch3P2Qd was also performed. A high-vacuum differential thermobalance (TG-DTA2410SA, manufactured by Bruker AXS) was used for the measurements. The measurements were performed at a heating rate of 10°C / min, at 10 Pa, under a nitrogen gas flow (flow rate of 2.0 mL / min). In the DTA-DTA, the temperature at which the weight determined by thermogravimetry decreased by 5% from the start of the measurement was found to be 261°C. Furthermore, when 5,12-diphenyl-5,12-dihydroquino[2,3-b]acridine-7,14-dione (DPQd), which has all cyclohexyl groups removed from the structure of ch3P2Qd, was measured under similar conditions, the sublimation temperature was 294°C. This result shows that the introduction of cyclohexyl groups has the effect of lowering the sublimation temperature and making it easier to sublimate. [Example]

[0439] In this example, a fabrication example of a light-emitting device according to one embodiment of the present invention and a comparative light-emitting device and the characteristics of the light-emitting device will be described. The structure of the light-emitting device fabricated in this example is the same as that shown in FIG. 1A. The structures and abbreviations of the compounds used are shown below.

[0440] [ka]

[0441] <Method for fabricating light-emitting device 1> An ITSO film was formed on a glass substrate to a thickness of 70 nm as an electrode 101. The electrode area of ​​the electrode 101 was 4 mm 2 (2mm x 2mm).

[0442] Next, 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) represented by the above structural formula (i) and molybdenum oxide (MoO3) were co-deposited on the electrode 101 as a hole injection layer 111, with the weight ratio (DBT3P-II:MoO3) being 1:0.5 and the thickness being 40 nm.

[0443] Next, 9-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]9H-carbazole (abbreviation: mCzFLP) represented by the above structural formula (ii) was vapor-deposited on the hole injection layer 111 to form a hole transport layer 112 to a thickness of 20 nm.

[0444] Next, on the hole transport layer 112, 8-(1,1'-biphenyl-4-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8BP-4mDBtPBfpm) represented by the above structural formula (iii), 3,3'-9H-carbazol-9-yl-biphenyl (abbreviation: mCBP) represented by the above structural formula (iv), and 2,4,5,6-tetra(9H-carbazol-9-yl)phenyl (abbreviation: mCBP) represented by the above structural formula (v) were deposited as the light-emitting layer 130. (8BP-4mDBtPBfpm) isophthalonitrile (abbreviation: 4CzIPN) and 5,12-bis(2,4,6-tricyclohexylphenyl)-5,12-dihydroquino[2,3-b]acridine-7,14-dione (abbreviation: ch3P2Qd) represented by the above structural formula (vi) were co-deposited in a weight ratio of 0.6:0.4:1:0.055 (=8BP-4mDBtPBfpm:mCBP:4CzIPN:ch3P2Qd) to a thickness of 31 nm.

[0445] In this light-emitting device, it is known from Non-Patent Document 1 that 4CzIPN is a TADF material. Also, ch3P2Qd is a fluorescent material having a protecting group.

[0446] Next, 8BP-4mDBtPBfpm was deposited on the light-emitting layer 130 to a thickness of 20 nm, and then NBPhen was deposited on the light-emitting layer 130 to a thickness of 15 nm to form the electron transport layer 118. Thereafter, LiF was deposited on the electron transport layer 118 to a thickness of 1 nm as the electron injection layer 119.

[0447] Then, aluminum (Al) was formed as electrode 102 on electron injection layer 119 to a thickness of 200 nm, and light-emitting device 1 was completed.

[0448] Next, in a glove box with a nitrogen atmosphere, a sealant was applied to the periphery of the organic material formed on the glass substrate, and the glass substrate and another glass substrate for sealing were bonded together. Then, ultraviolet light with a wavelength of 365 nm was applied at 6 J / cm. 2The light-emitting device 1 was irradiated with light and then heat-treated at 80° C. for 1 hour, and then fixed to the glass substrate on which the organic material was formed, thereby sealing the light-emitting device 1.

[0449] <Method for producing comparative light-emitting devices> Comparative light-emitting device 1 was fabricated in the same manner as light-emitting device 1, except that the ch3P2Qd in the light-emitting layer of light-emitting device 1 was replaced with N,N'-diphenylquinacridone (abbreviation: DPQd) represented by the structural formula (viii) above, and the weight ratio was 8BP-4mDBtPBfpm:mCBP:4CzIPN:DPQd = 0.6:0.4:1:0.052. That is, comparative light-emitting device 1 is a light-emitting device using a fluorescent material without a protecting group. Comparative light-emitting device 2 was fabricated by co-evaporating the light-emitting layer of light-emitting device 1 in a weight ratio of 8BP-4mDBtPBfpm:mCBP:4CzIPN = 0.6:0.4:1 to a thickness of 30 nm. That is, comparative light-emitting device 2 is a light-emitting device that does not use the organic compound described in embodiment 1.

[0450] The device structures of the light-emitting device 1 and the comparative light-emitting device 1 are shown below.

[0451] [Table 1]

[0452] [Table 2]

[0453] [Table 3]

[0454] <Characteristics of Light-Emitting Device 1, Comparative Light-Emitting Device 1, and Comparative Light-Emitting Device 2> Next, the characteristics of the prepared light-emitting device 1, comparative light-emitting device 1, and comparative light-emitting device 2 were measured. A spectroradiometer (SR-UL1R, manufactured by Topcon Corporation) was used to measure the luminance, CIE chromaticity, and electroluminescence (EL) spectrum.

[0455] The luminance-current density characteristics of light-emitting device 1, comparative light-emitting device 1, and comparative light-emitting device 2 are shown in Figure 17, their current efficiency-luminance characteristics in Figure 18, their luminance-voltage characteristics in Figure 19, their current density-voltage characteristics in Figure 20, their power efficiency-luminance characteristics in Figure 21, and their external quantum efficiency-luminance characteristics in Figure 22. 2 The electroluminescence spectrum when a current was passed at a current density of 1000 kJ / s is shown in Fig. 23. The measurement was carried out at room temperature (in an atmosphere maintained at 23°C).

[0456] Also, 1000cd / m 2 The device characteristics of light-emitting device 1, comparative light-emitting device 1, and comparative light-emitting device 2 in the vicinity are shown in Table 4 below.

[0457] [Table 4]

[0458] Light-emitting device 1 is a light-emitting element in which 4CzIPN serves as an energy donor and transfers energy to ch3P2Qd, an organic compound (fluorescent material) shown in embodiment 1, thereby emitting light from ch3P2Qd. Comparative light-emitting device 1 is a light-emitting element in which 4CzIPN serves as an energy donor and transfers energy to DPQd, an organic compound (fluorescent material) having no protecting group, thereby emitting light from DPQd. Comparative light-emitting device 2 is a light-emitting element in which light is emitted from 4CzIPN.

[0459] As shown in Figure 23, the EL spectrum of Light-Emitting Device 1 exhibited a very sharp spectral shape with a peak wavelength of 521 nm and a full width at half maximum of 26 nm. This is due to the emission of the fluorescent material ch3P2Qd. The EL spectrum of Comparative Light-Emitting Device 1 also exhibited a sharp spectral shape with a peak wavelength of 526 nm and a full width at half maximum of 53 nm. This is due to the emission of the fluorescent material DPQd. The EL spectrum of Comparative Light-Emitting Device 2 exhibited a spectral shape with a peak wavelength of 540 nm and a full width at half maximum of 81 nm. This is due to the emission of the TADF material 4CzIPN. The emission spectra of Comparative Light-Emitting Device 2 clearly differ from those of Light-Emitting Device 1 and Comparative Light-Emitting Device 1, indicating that the observed emission is from a different light-emitting substance.

[0460] As can be seen from FIG. 20, the driving voltages of the light-emitting device 1, the comparative light-emitting device 1, and the comparative light-emitting device 2 are almost the same.

[0461] Comparative light-emitting device 2 exhibited a high external quantum efficiency exceeding 20% ​​at maximum. This indicates that 4CzIPN exhibits good luminescence efficiency as a TADF material. Furthermore, light-emitting device 1 achieved a high external quantum efficiency exceeding 18% at maximum. Generally, the probability of generating singlet excitons generated by the recombination of carriers (holes and electrons) injected from a pair of electrodes is 25% at maximum. Therefore, assuming a 30% light extraction efficiency, the external quantum efficiency of a fluorescent light-emitting device is 7.5% at maximum. Since light-emitting device 1 achieved an external quantum efficiency of more than 7.5%, it is clear that in addition to emission from singlet excitons, emission from the fluorescent material is also derived from energy transfer from triplet excitons. On the other hand, the external quantum efficiency of comparative light-emitting device 1 was only about 8%, less than half that of light-emitting device 1. This indicates that comparative light-emitting device 1 is unable to efficiently convert triplet excitation energy into light emission. In other words, by using ch3P2Qd, which is a compound according to one embodiment of the present invention, non-radiative deactivation of triplet excitons is suppressed, and both singlet excitation energy and triplet excitation energy are efficiently converted into light emission from the fluorescent material.

[0462] Furthermore, the light-emitting device 1 exhibits high luminous efficiency and has a narrow half-width emission spectrum, so that the light-emitting device 1 has a luminous efficiency of 2.5 mA / cm 2 23, it was found that the peak intensity of light-emitting device 1 was the highest. Furthermore, light-emitting device 1 has a narrow half-width of the emission spectrum and good color purity, making it suitable for use in displays.

[0463] Furthermore, the peak wavelength of the EL spectrum of Light-Emitting Device 1 was shorter than that of Comparative Light-Emitting Device 2. Therefore, as shown in Table 4, Light-Emitting Device 1 exhibited better color purity and good green light emission with a high chromaticity y than Comparative Light-Emitting Device 2, making it suitable for display applications. This is due to the small Stokes shift of ch3P2Qd, as shown in Figure 16. Thus, using a fused heteroaromatic ring such as quinacridone as the luminophore is preferable because it allows the production of a fluorescent light-emitting material with a small Stokes shift.

[0464] Next, the electrochemical properties (oxidation and reduction properties) of 8BP-4mDBtPBfpm and mCBP used in the light-emitting layer of each light-emitting device were measured by cyclic voltammetry (CV). The measurement method was the same as in Example 1.

[0465] The HOMO level and LUMO level of 8BP-4mDBtPBfpm calculated from the results of CV measurements were −6.21 eV and −3.01 eV, respectively, and the HOMO level and LUMO level of mCBP were −5.93 eV and −2.22 eV.

[0466] As described above, the LUMO level of 8BP-4mDBtPBfpm is lower than that of mCBP, and the HOMO level of mCBP is higher than that of 8BP-4mDBtPBfpm. Therefore, when this compound is used in the light-emitting layer, electrons and holes are efficiently injected into 8BP-4mDBtPBfpm and mCBP, respectively, and 8BP-4mDBtPBfpm and mCBP can form an exciplex. [Example]

[0467] <Synthesis Example 2> Example 1 This example describes a synthesis method for 3,10-di-tert-butyl-5,12-bis(2,4,6-tricyclohexylphenyl)-5,12-dihydroquino[2,3-b]acridine-7,14-dione (abbreviation: 3,10tBu-chPQd), an organic compound according to one embodiment of the present invention. The structural formula of 3,10tBu-chPQd is shown below.

[0468] [ka]

[0469] <Step 1: Synthesis of dimethyl 2,5-dihydro-3,6-bis{(3-tert-butylphenyl)amino)terephthalate> 5.0 g (22 mmol) of dimethyl 1,4-cyclohexanedione-2,5-dicarboxylate, 7.5 g (50 mmol) of 3-tert-butylaniline, 75 mL of acetic acid, and 75 mL of ethanol were placed in a 300 mL three-neck flask equipped with a reflux condenser and refluxed at 115 °C for 7 hours. After cooling, the precipitated red solid was collected by suction filtration and washed with hexane and methanol. Water was added to the filtrate obtained by suction filtration, and the aqueous layer was extracted with toluene. The organic layer was washed with aqueous sodium bicarbonate and saturated brine and dried over magnesium sulfate. The magnesium sulfate was removed from the mixture by gravity filtration, and the resulting solution was concentrated. The solids obtained by suction filtration and concentration combined to yield 5.6 g of red solid. LC / MS analysis of the resulting red solid revealed m / z values ​​of 491 and 489, indicating that they were the target product and its oxide. This mixture was used directly in Step 2. The synthesis scheme for Step 1 is shown below.

[0470] [ka]

[0471] <Step 2: Synthesis of dimethyl 2,5-bis{(3-tert-butylphenyl)amino}terephthalate> A mixture of 5.6 g of dimethyl 2,5-dihydro-3,6-bis{(3-tert-butylphenyl)amino)terephthalate and its oxide obtained in Step 1, 4.5 g (35 mmol) of iodine, and 0.15 L of toluene was placed in a 500 mL three-neck flask equipped with a reflux condenser and refluxed at 120 °C for 10 hours with stirring. After stirring, the precipitated solid was collected by suction filtration and washed with hexane and methanol to yield 2.7 g of a red solid. Water was added to the filtrate obtained by suction filtration, and the aqueous layer was extracted with toluene. The organic layer was washed with water and then with aqueous sodium thiosulfate. The organic layer was washed with saturated brine and dried over magnesium sulfate. The magnesium sulfate was removed from the mixture by gravity filtration, and the filtrate was concentrated to yield a red solid. Methanol was added to the solid to form a slurry, and the solid was collected by suction filtration and washed with methanol and hexane. This process yielded 2.0 g of a red solid. This solid was combined with the solid obtained by suction filtration to obtain 4.7 g of the target compound in a 44% yield. LC / MS analysis of the resulting red solid showed that it had an m / z of 489, indicating that it was the target compound. The synthesis scheme for Step 2 is shown below.

[0472] [ka]

[0473] <Step 3: Synthesis of dimethyl 2,5-bis[{3-(tert-butyl)phenyl}(2,4,6-tricyclohexylphenyl)amino]terephthalate> 2.4 g (5.0 mmol) of 1,4-benzenedicarboxylic acid, 2,5-bis{(3-tert-butylphenyl)amino}-, dimethyl ester (obtained in Step 2), 4.4 g (11 mmol) of 1-bromo-2,4,6-tricyclohexylbenzene, 1.3 g (20 mmol) of copper, 0.95 g (5.0 mmol) of copper iodide, 2.8 g (20 mmol) of potassium carbonate, and 10 mL of diphenyl ether were placed in a 200 mL three-neck flask equipped with a reflux condenser. The mixture was degassed under reduced pressure and then purged with nitrogen. The mixture was stirred at 240 °C for 8 hours and then at 260 °C for 2 hours. Toluene and water were added to the resulting mixture, and the mixture was suction filtered to remove insoluble materials. The resulting filtrate was separated into organic and aqueous layers, and the organic layer was washed twice with water. The organic layer was washed with saturated brine and dried over magnesium sulfate. Magnesium sulfate was removed from the resulting mixture by gravity filtration, and the resulting filtrate was concentrated to yield a dark brown viscous solid. The resulting solid was purified by silica gel chromatography (eluent: hexane:toluene = 2:1) to obtain 0.99 g of the desired orange-yellow solid in a 17% yield. LC\MS analysis of the resulting orange-yellow solid revealed that it had an m / z of 1133, confirming that it was the desired product. The synthesis scheme for Step 3 is shown below.

[0474] [ka]

[0475] <Step 4: Synthesis of 3,10-di-tert-butyl-5,12-bis(2,4,6-tricyclohexylphenyl)-5,12-dihydroquino[2,3-b]acridine-7,14-dione (abbreviation: 3,10tBu-ch3P2Qd)> 0.73 g of the 1,4-benzenedicarboxylic acid, 2,5-bis{(3-tert-butylphenyl)amino}-,N'-(2,4,6-tricyclohexylphenyl)amino]-, dimethyl ester obtained in Step 3 and 10 mL of methanesulfonic acid were placed in a 100 mL three-neck flask and stirred at 140 °C for 1 hour. After cooling the mixture, the reaction was quenched by adding ice water. Toluene was added to the resulting mixture, and the aqueous layer was extracted. The resulting organic layer was washed with water and then with saturated aqueous sodium bicarbonate. The organic layer was washed with saturated brine and dried over magnesium sulfate. The magnesium sulfate was removed from the resulting mixture by gravity filtration, and the resulting filtrate was concentrated to yield 0.62 g of an orange-yellow solid. The resulting solid was purified by silica gel chromatography (developing solvent: toluene) to obtain 0.39 g of the desired orange solid in 57% yield. The scheme for Step 4 is shown below.

[0476] [ka]

[0477] 0.30 g of the resulting orange solid was purified by train sublimation. The purification was carried out by heating the solid at 345 °C under a pressure of 5.0 Pa for 16 hours while flowing argon at 10 mL / min. After the purification, 0.25 g of the target orange solid was obtained with a recovery rate of 83%.

[0478] The obtained solid 1 The 1 H NMR charts are shown in Figures 24A and 24B, and the numerical data are shown below. This indicates that the target compound was obtained. 1H NMR (dichloromethane-d2,300MHz): δ=8.46(d,J=8.4Hz,2H),7.98(s,2H),7.35(s,4H),7.31(dd,J=4.2Hz,1.8Hz,2H),6.61(d,J=1.5Hz,2H) ,2.81-2.65(m,2H),2.16-2.05(m,4H),2.00-1.77(m,10H),1.71-1.28(m,38H),1.16(s,18H),1.13-0.98(m,4H),0.85-0.52(m,8H)

[0479] Next, the UV-visible absorption spectrum (hereinafter simply referred to as "absorption spectrum") and emission spectrum of a dichloromethane solution of 3,10tBu-ch3P2Qd were measured. A UV-visible spectrophotometer (JASCO Corporation, V-550) was used to measure the absorption spectrum. The absorption spectrum of the solution was calculated by subtracting the absorption spectrum measured with only dichloromethane in a quartz cell. A fluorometer (JASCO Corporation, FP-8600) was used to measure the emission spectrum. The quantum yield was measured using an absolute PL quantum yield measurement system (Hamamatsu Photonics, Quantaurus-QY).

[0480] The measurement results of the absorption spectrum and emission spectrum of the obtained dichloromethane solution are shown in Figure 25. The horizontal axis represents wavelength, and the vertical axis represents absorption intensity and emission intensity. The horizontal axis represents wavelength, and the vertical axis represents absorption intensity and emission intensity. From the results in Figure 25, the dichloromethane solution of 3,10tBu-ch3P2Qd exhibited absorption peaks around 512 nm, 480 nm, and 449 nm, and emission wavelength peaks at 617 nm, 565 nm, and 528 nm (excitation wavelength: 480 nm).

[0481] Furthermore, the quantum yield in dichloromethane solution was measured and found to be very high at 91%, indicating that 3,10tBu-ch3P2Qd is suitable as a light-emitting material.

[0482] The HOMO and LUMO levels of 3,10tBu-ch3P2Qd were calculated based on cyclic voltammetry (CV) measurements. An electrochemical analyzer (BAS Corporation, Model ALS Model 600A or 600C) was used. The solution used for CV measurements was prepared by dissolving the supporting electrolyte tetra-n-butylammonium perchlorate (n-Bu4NClO4) (Tokyo Chemical Industry Co., Ltd., Catalog No. T0836) at a concentration of 100 mmol / L in dehydrated dimethylformamide (DMF) (Aldrich Corporation, 99.8%, Catalog No. 22705-6) and further dissolving the target compound at a concentration of 2 mmol / L.

[0483] The scan rate during CV measurement was standardized to 0.1 V / sec, and the oxidation potential Ea [V] and reduction potential Ec [V] relative to the reference electrode were measured. Ea was the midpoint potential of the oxidation-reduction wave, and Ec was the midpoint potential of the reduction-oxidation wave. Here, since the potential energy of the reference electrode used in this example relative to the vacuum level is known to be -4.94 [eV], the HOMO level and LUMO level can be calculated from the formulas HOMO level [eV] = -4.94 - Ea and LUMO level [eV] = -4.94 - Ec, respectively.

[0484] In addition, CV measurements were performed 100 times, and the oxidation-reduction wave at the 100th cycle was compared with that at the first cycle to examine the electrical stability of the compound. Measurement of the oxidation potential Ea [V] of 3,10tBu-ch3P2Qd revealed that the HOMO level was -5.77 eV. Measurement of the reduction potential Ec [V] revealed that the LUMO level was -3.18 eV. Furthermore, when comparing the waveforms after the first and 100th cycles in the repeated oxidation-reduction wave measurements, the Ea measurement maintained 75% of the peak intensity. [Example]

[0485] In this example, a fabrication example of a light-emitting device according to one embodiment of the present invention and a comparative light-emitting device and the characteristics of the light-emitting device will be described. The structure of the light-emitting device fabricated in this example is the same as that shown in FIG. 1A. The structures and abbreviations of the compounds used are shown below.

[0486] [ka]

[0487] <Method for fabricating light-emitting device 2> An ITSO film was formed on a glass substrate to a thickness of 70 nm as an electrode 101. The electrode area of ​​the electrode 101 was 4 mm 2 (2mm x 2mm).

[0488] Next, 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) represented by the above structural formula (i) and molybdenum oxide were co-deposited on the electrode 101 as a hole injection layer 111, with the weight ratio (DBT3P-II:molybdenum oxide) being 1:0.5 and the thickness being 40 nm.

[0489] Next, 9-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]9H-carbazole (abbreviation: mCzFLP) represented by the above structural formula (ii) was vapor-deposited on the hole injection layer 111 to form a hole transport layer 112 to a thickness of 20 nm.

[0490] Next, on the hole transport layer 112, as the light-emitting layer 130, 3,3'-9H-carbazol-9-yl-biphenyl (abbreviation: mCBP) represented by the above structural formula (iv), 2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile (abbreviation: 4CzIPN) represented by the above structural formula (v), and 3,10-di-tert-butyl-5,12-bis(2,4,6-tricyclohexylphenyl)-5,12-dihydroquino[2,3-b]acridine-7,14-dione (abbreviation: 3,10tBu-ch3P2Qd) represented by the above structural formula (ix) were co-deposited in a weight ratio of 1:1:0.05 (=mCBP:4CzIPN:3,10tBu-ch3P2Qd) to a thickness of 40 nm.

[0491] In this light-emitting device, it is known from Non-Patent Document 1 that 4CzIPN is a TADF material. Also, 3,10tBu-ch3P2Qd is a fluorescent material having a protecting group.

[0492] Next, 9,9'-(pyrimidine-4,6-diyldi-3,1-phenylene)bis(9H-carbazole) (abbreviation: 4,6CzP2Pm) represented by the above structural formula (x) was deposited on the light-emitting layer 130 to a thickness of 20 nm, and then NBPhen was deposited on the light-emitting layer 130 to a thickness of 15 nm to form the electron-transporting layer 118. Thereafter, LiF was deposited on the electron-transporting layer 118 to a thickness of 1 nm as the electron-injecting layer 119.

[0493] Thereafter, an electrode 102 made of aluminum (Al) was formed on the electron injection layer 119 to a thickness of 200 nm, thereby completing the light-emitting device 2.

[0494] Next, in a glove box with a nitrogen atmosphere, a sealant was applied to the periphery of the organic material formed on the glass substrate, and the glass substrate and another glass substrate for sealing were bonded together. Then, ultraviolet light with a wavelength of 365 nm was applied at 6 J / cm. 2 The light-emitting device 2 was irradiated with light and then heat-treated at 80° C. for 1 hour, and fixed to the glass substrate on which the organic material was formed, thereby sealing the light-emitting device 2.

[0495] <Method for producing comparative light-emitting devices> Comparative light-emitting device 3 was fabricated in the same manner as light-emitting device 2, except that the 3,10tBu-ch3P2Qd in the light-emitting layer of light-emitting device 2 was replaced with N,N'-diphenylquinacridone (abbreviation: DPQd) represented by structural formula (viii) above, the weight ratio of mCBP:4CzIPN:DPQd was 1:1:0.05, and the thickness was 30 nm. That is, comparative light-emitting device 3 is a light-emitting device that uses a fluorescent material without a protecting group instead of the organic compound of the present invention. Comparative light-emitting device 4 was fabricated in the same manner as light-emitting device 2, except that the light-emitting layer of light-emitting device 2 was formed in a weight ratio of mCBP:4CzIPN = 1:1 and a thickness of 30 nm. That is, comparative light-emitting device 4 is a light-emitting device that does not use the organic compound of the present invention.

[0496] The device structures of light-emitting device 2, comparative light-emitting device 3, and comparative light-emitting device 4 are shown below.

[0497] [Table 5]

[0498] [Table 6]

[0499] [Table 7]

[0500] <Characteristics of Light-Emitting Device 2, Comparative Light-Emitting Device 3, and Comparative Light-Emitting Device 4> Next, the characteristics of the prepared light-emitting device 2, comparative light-emitting device 3, and comparative light-emitting device 4 were measured. A spectroradiometer (SR-UL1R, manufactured by Topcon Corporation) was used to measure the luminance, CIE chromaticity, and electroluminescence (EL) spectrum.

[0501] The luminance-current density characteristics of light-emitting device 2, comparative light-emitting device 3, and comparative light-emitting device 4 are shown in Figure 26, their current efficiency-luminance characteristics in Figure 27, their luminance-voltage characteristics in Figure 28, their current density-voltage characteristics in Figure 29, their power efficiency-luminance characteristics in Figure 30, and their external quantum efficiency-luminance characteristics in Figure 31. 2 The electroluminescence spectrum when a current was passed at a current density of 1000 kJ / s is shown in Fig. 32. The measurement was carried out at room temperature (in an atmosphere maintained at 23°C).

[0502] Also, 1000cd / m 2 Table 8 shows the device characteristics of light-emitting device 2, comparative light-emitting device 3, and comparative light-emitting device 4 in the vicinity of 1000 nm.

[0503] [Table 8]

[0504] Light-emitting device 2 is a light-emitting element in which 4CzIPN, a TADF material, serves as an energy donor and transfers energy to 3,10tBu-ch3P2Qd, an organic compound (fluorescent material) according to one embodiment of the present invention, thereby emitting light from 3,10tBu-ch3P2Qd. Comparative light-emitting device 3 is a light-emitting element in which 4CzIPN serves as an energy donor and transfers energy to DPQd, an organic compound (fluorescent material) having no protecting groups, thereby emitting light from DPQd. Comparative light-emitting device 4 is a light-emitting device in which 4CzIPN emits light.

[0505] As shown in Figure 32, the EL spectrum of Light-Emitting Device 2 exhibited a very sharp spectral shape with a peak wavelength of 521 nm and a full width at half maximum of 53 nm. This is due to the emission of the fluorescent material 3,10tBu-ch3P2Qd. The EL spectrum of Comparative Light-Emitting Device 3 also exhibited a sharp spectral shape with a peak wavelength of 526 nm and a full width at half maximum of 56 nm. This is due to the emission of the fluorescent material DPQd. The EL spectrum of Comparative Light-Emitting Device 4 exhibited a spectral shape with a peak wavelength of 543 nm and a full width at half maximum of 82 nm. This is due to the emission of the TADF material 4CzIPN. The emission spectra of Comparative Light-Emitting Device 4 are clearly different from those of Light-Emitting Device 2 and Comparative Light-Emitting Device 3, indicating that the observed emission is from a different light-emitting substance.

[0506] Comparative light-emitting device 4 exhibited a high external quantum efficiency of approximately 20% at maximum. This indicates that 4CzIPN exhibits good luminescence efficiency as a TADF material. Furthermore, light-emitting device 2 achieved a high external quantum efficiency of more than 18% at maximum. Generally, the probability of generating singlet excitons through the recombination of carriers (holes and electrons) injected from a pair of electrodes is 25% at maximum. Therefore, assuming a 30% light extraction efficiency, the external quantum efficiency of a fluorescent light-emitting device is 7.5% at maximum. Light-emitting device 2 achieved an external quantum efficiency of more than 7.5%, indicating that in addition to emission from singlet excitons, the fluorescent material also emits light from energy transfer from triplet excitons. On the other hand, the external quantum efficiency of comparative light-emitting device 3 was only around 9%, approximately half that of light-emitting device 2. This indicates that comparative light-emitting device 3 does not efficiently convert triplet excitation energy into light emission. In other words, by using 3,10tBu-ch3P2Qd, which is a compound according to one embodiment of the present invention, non-radiative deactivation of triplet excitons is suppressed, and both singlet excitation energy and triplet excitation energy are efficiently converted into light emission from the fluorescent material.

[0507] Furthermore, the light-emitting device 2 exhibits high luminous efficiency and a narrow full width at half maximum of the emission spectrum, so that the light-emitting device 2 has a luminous efficiency of 2.5 mA / cm 2 32, it was found that the peak intensity of light-emitting device 2 was the highest. Furthermore, light-emitting device 2 has a narrow half-width of the emission spectrum and good color purity, making it suitable for display applications.

[0508] Furthermore, the peak wavelength of the EL spectrum of Light-Emitting Device 2 was shorter than that of Comparative Light-Emitting Device 4. Therefore, as shown in Table 4, Light-Emitting Device 2 exhibited good green emission with better color purity and a high chromaticity y than Comparative Light-Emitting Device 4, making it suitable for display applications. This is due to the small Stokes shift of 3,10tBu-ch3P2Qd, as shown in Figure 25. Thus, using a fused heteroaromatic ring such as quinacridone as the luminophore is preferable because it allows the production of a fluorescent light-emitting material with a small Stokes shift.

[0509] 33 is a graph showing the effect of dopant concentration on luminous efficiency. Light-emitting devices different from light-emitting device 2 and comparative light-emitting device 3 only in dopant concentration were fabricated, and 2 The external quantum efficiency was plotted around 1000 s. As a result, it was found that the external quantum efficiency of devices using DPQd as a dopant decreased significantly as the dopant concentration increased, whereas that of devices using 3,10tBu-ch3P2Qd as a dopant did not decrease significantly even with increasing concentration. This is presumably because the protective group in 3,10tBu-ch3P2Qd allows the dopants to be spaced apart at an appropriate distance, thereby significantly suppressing concentration quenching. Thus, the light-emitting device of one embodiment of the present invention has a wide manufacturing margin for dopant concentration and is easy to manufacture. [Example]

[0510] In this example, a fabrication example of a light-emitting device according to one embodiment of the present invention and a comparative light-emitting device and the characteristics of the light-emitting device will be described. The structure of the light-emitting device fabricated in this example is the same as that shown in FIG. 1A. The structures and abbreviations of the compounds used are shown below.

[0511] [ka]

[0512] <Method for producing light-emitting device 3> An ITSO film was formed on a glass substrate to a thickness of 70 nm as an electrode 101. The electrode area of ​​the electrode 101 was 4 mm 2 (2mm x 2mm).

[0513] Next, 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) represented by the above structural formula (i) and molybdenum oxide were co-deposited on the electrode 101 as a hole injection layer 111, with the weight ratio (DBT3P-II:molybdenum oxide) being 1:0.5 and the thickness being 40 nm.

[0514] Next, 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP) represented by the above structural formula (xi) was vapor-deposited on the hole injection layer 111 to form a hole transport layer 112 to a thickness of 20 nm.

[0515] Next, on the hole transport layer 112, a light-emitting layer 130 was formed by depositing 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02) represented by the above structural formula (xii), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP) represented by the above structural formula (xiii), and [2-(4-methyl-5-phenyl-2-pyridinyl-κN)phenyl-κC]bis[2-(2-pyridinyl-κN)phenyl-κC] represented by the above structural formula (xiv). [C] Iridium (abbreviation: [Ir(ppy)2(mdppy)]) and 3,10-di-tert-butyl-5,12-bis(2,4,6-tricyclohexylphenyl)-5,12-dihydroquino[2,3-b]acridine-7,14-dione (abbreviation: 3,10tBu-ch3P2Qd) represented by the above structural formula (ix) were co-evaporated in a weight ratio of 0.5:0.5:0.1:0.01 (=mPCCzPTzn-02:PCCP:[Ir(ppy)2(mdppy)]:3,10tBu-ch3P2Qd) to a thickness of 40 nm.

[0516] In this light-emitting device, [Ir(ppy)2(mdppy)] is known to be a phosphorescent material, and 3,10tBu-ch3P2Qd is a fluorescent material with a protecting group.

[0517] Next, mPCCzPTzn-02 was deposited on the light-emitting layer 130 to a thickness of 20 nm, and then NBPhen was deposited on it to a thickness of 10 nm to form the electron transport layer 118. Then, LiF was deposited on the electron transport layer 118 to a thickness of 1 nm as the electron injection layer 119.

[0518] Thereafter, an electrode 102 made of aluminum (Al) was formed on the electron injection layer 119 to a thickness of 200 nm, thereby completing the light-emitting device 3.

[0519] Next, in a glove box with a nitrogen atmosphere, a sealant was applied to the periphery of the organic material formed on the glass substrate, and the glass substrate and another glass substrate for sealing were bonded together. Then, ultraviolet light with a wavelength of 365 nm was applied at 6 J / cm. 2 The light-emitting device 3 was irradiated with light and then heat-treated at 80° C. for 1 hour, and fixed to the glass substrate on which the organic material was formed, thereby sealing the light-emitting device 3.

[0520] <Method for producing comparative light-emitting devices> Comparative light-emitting device 5 was formed in the same manner as light-emitting device 3, except that 3,10tBu-ch3P2Qd in the light-emitting layer of light-emitting device 3 was replaced with N,N'-diphenylquinacridone (abbreviation: DPQd) represented by the above structural formula (viii). In other words, comparative light-emitting device 5 is a light-emitting device that uses a fluorescent material having no protecting group instead of the organic compound of the present invention.

[0521] The device structures of light-emitting device 3 and comparative light-emitting device 5 are shown in the table below.

[0522] [Table 9]

[0523] [Table 10]

[0524] <Characteristics of Light-Emitting Device 3 and Comparative Light-Emitting Device 5> Next, the properties of the fabricated light-emitting device 3 and comparative light-emitting device 5 were measured. A spectroradiometer (SR-UL1R, manufactured by Topcon Corporation) was used to measure the luminance, CIE chromaticity, and electroluminescence (EL) spectrum.

[0525] The luminance-current density characteristics of light-emitting device 3 and comparative light-emitting device 5 are shown in Figure 34, their current efficiency-luminance characteristics in Figure 35, their luminance-voltage characteristics in Figure 36, their current density-voltage characteristics in Figure 37, their power efficiency-luminance characteristics in Figure 38, and their external quantum efficiency-luminance characteristics in Figure 39.2 The electroluminescence spectrum when a current was passed at a current density of 1000 kJ / s is shown in Figure 40. The measurement was carried out at room temperature (in an atmosphere maintained at 23°C).

[0526] Also, 1000cd / m 2 Table 11 shows the device characteristics of the light-emitting device 3 and the comparative light-emitting device 5 in the vicinity of 1000 nm.

[0527] [Table 11]

[0528] Light-emitting device 3 is a light-emitting element in which the phosphorescent material [Ir(ppy)2(mdppy)] serves as an energy donor and transfers energy to 3,10tBu-ch3P2Qd, an organic compound (fluorescent material) according to one embodiment of the present invention, thereby emitting light from 3,10tBu-ch3P2Qd. Comparative light-emitting device 5 is a light-emitting element in which the energy donor [Ir(ppy)2(mdppy)] serves as an energy donor and transfers energy to DPQd, an organic compound (fluorescent material) having no protecting groups, thereby emitting light from DPQd.

[0529] As shown in Figure 40, the EL spectrum of Light-Emitting Device 3 exhibited a very sharp spectral shape with a peak wavelength of 519 nm and a full width at half maximum of 57 nm. This is due to the emission of the fluorescent material 3,10tBu-ch3P2Qd. The EL spectrum of Comparative Light-Emitting Device 5 exhibited a sharp spectral shape with a peak wavelength of 524 nm and a full width at half maximum of 37 nm. This is due to the emission of the fluorescent material DPQd.

[0530] The light-emitting device 3 exhibited a high external quantum efficiency exceeding 13% at maximum. Generally, the probability of generating singlet excitons through the recombination of carriers (holes and electrons) injected from a pair of electrodes is 25% at maximum. Therefore, assuming a 30% light extraction efficiency, the external quantum efficiency of a fluorescent light-emitting device is 7.5% at maximum. Since the light-emitting device 3 exhibited an external quantum efficiency of more than 7.5%, it can be seen that the fluorescent material emits light due to energy transfer from triplet excitons in addition to light emitted from singlet excitons. On the other hand, the external quantum efficiency of the comparative light-emitting device 5 was only in the 5% range at maximum, less than half that of the light-emitting device 3. Therefore, it can be seen that the triplet excitation energy was not efficiently converted into light emission in the comparative light-emitting device 5. In other words, the use of 3,10tBu-ch3P2Qd, a compound according to one embodiment of the present invention, suppresses nonradiative deactivation of triplet excitons, and both singlet excitation energy and triplet excitation energy are efficiently converted into light emission from the fluorescent material.

[0531] Next, the electrochemical properties (oxidation and reduction properties) of mPCCzPTzn-02 and PCCP used in the light-emitting layer of each light-emitting device were measured by cyclic voltammetry (CV) using the same method as in Example 1.

[0532] The HOMO level and LUMO level of mPCCzPTzn-02 calculated from the results of CV measurement were −5.69 eV and −3.00 eV, respectively, and the HOMO level and LUMO level of PCCP were −5.63 eV and −1.96 eV.

[0533] As described above, the LUMO level of mPCCzPTzn-02 is lower than that of PCCP, and the HOMO level of PCCP is higher than that of mPCCzPTzn-02. Therefore, when this compound is used in an emissive layer, electrons and holes are efficiently injected into mPCCzPTzn-02 and PCCP, respectively, and mPCCzPTzn-02 and PCCP can form an exciplex. The formation of the exciplex allows efficient energy transfer from the exciplex to the energy donor [Ir(ppy)2(mdppy)], contributing to improved luminous efficiency. [Explanation of symbols]

[0534] 100: EL layer, 101: electrode, 102: electrode, 106: light-emitting unit, 108: light-emitting unit, 111: hole injection layer, 112: hole transport layer, 113: electron transport layer, 114: electron injection layer, 115: charge generation layer, 116: hole injection layer, 117: hole transport layer, 118: electron transport layer, 119: electron injection layer, 120: light-emitting layer, 130: light-emitting layer, 131: compound, 132: compound, 133: compound, 134: compound, 135: compound, 150: light-emitting device, 170: light-emitting layer, 250: light-emitting device, 301: guest material, 302: guest material, 310: luminophore, 3 20: Protecting group, 330: Host material, 601: Source side driving circuit, 602: Pixel portion, 603: Gate side driving circuit, 604: Sealing substrate, 605: Sealing material, 607: Space, 608: Wiring, 609: FPC, 610: Element substrate, 611: Switching TFT, 612: Current control TFT, 613: Electrode, 614: Insulator, 616: EL layer, 617: Electrode, 618: Light emitting device, 623: N-channel TFT, 624: P-channel TFT, 625: Desiccant, 900: Portable information terminal, 901: Housing, 902: Housing, 903: Display portion, 905: Hinge portion, 910 : Portable information terminal, 911: housing, 912: display unit, 913: operation button, 914: external connection port, 915: speaker, 916: microphone, 917: camera, 920: camera, 921: housing, 922: display unit, 923: operation button, 924: shutter button, 926: lens, 1001: substrate, 1002: base insulating film, 1003: gate insulating film, 1006: gate electrode, 1007: gate electrode, 1008: gate electrode, 1020: interlayer insulating film, 1021: interlayer insulating film, 1022: electrode, 1024B: electrode, 1024G: electrode, 1024R: electrode, 1024W : electrode, 1025B: lower electrode, 1025G: lower electrode, 1025R: lower electrode, 1025W: lower electrode, 1026: partition wall, 1028: EL layer, 1029: electrode, 1031: sealing substrate, 1032: sealing material, 1033: base material, 1034B: colored layer, 1034G: colored layer, 1034R: colored layer, 1036: overcoat layer, 1037: interlayer insulating film, 1040: pixel section, 1041: driving circuit section, 1042: peripheral section, 1044B: blue pixel, 1044G: green pixel, 1044R: red pixel, 1044W: white pixel, 2100: robot, 2101: illuminance sensor,2102: microphone, 2103: upper camera, 2104: speaker, 2105: display, 2106: lower camera, 2107: obstacle sensor, 2108: movement mechanism, 2110: computing unit, 5000: housing, 5001: display unit, 5002: display unit, 5003: speaker, 5004: LED lamp, 5005: operation key, 5006: connection terminal, 5007: sensor, 5008: microphone Phone, 5012: support part, 5013: earphone, 5100: cleaning robot, 5101: display, 5102: camera, 5103: brush, 5104: operation button, 5120: dust, 5140: portable electronic device, 5150: mobile information terminal, 5151: housing, 5152: display area, 5153: bending part, 8501: lighting device, 8502: lighting device, 8503: lighting device, 8504: lighting device,

Claims

1. A light-emitting layer is disposed between a pair of electrodes, the light-emitting layer comprises a first compound, a second compound, and a third compound; the first compound and the second compound are a combination that forms an exciplex, The third compound is a compound represented by the following general formula (G1-2): 【Chemistry 1】 (However, in the above general formula (G1-2), R １ ~R １０ each independently represents one of hydrogen, an alkyl group having from 3 to 10 carbon atoms, and a substituted or unsubstituted cycloalkyl group having from 3 to 10 carbon atoms; Ar １ and Ar ２ Each of Ar and Ar each independently represents an aromatic hydrocarbon group having 6 to 13 carbon atoms and having three or more substituents. １ and Ar ２ The substituents of are a plurality of groups selected from an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, and a cycloalkyl group having 7 to 10 carbon atoms and having a bridged structure.

2. In claim 1, The Ar １ and Ar ２ wherein each of the groups has 3 to 5 substituents.

3. In claim 1 or claim 2, The Ar １ and Ar ２ is a phenyl group having a substituent.

4. In claim 3, The Ar １ and Ar ２ The substituents each of Ar １ and Ar ２ and a light-emitting device in which the compound is bonded to both the ortho and para positions.

5. In any one of claims 1 to 4, The Ar １ and Ar ２ and wherein each of the above has three substituents.

6. In any one of claims 1 to 5, The Ar １ and Ar ２ wherein each of the substituents is a cyclohexyl group.

7. A light-emitting layer is disposed between a pair of electrodes, the light-emitting layer comprises a first compound, a second compound, and a third compound; the first compound and the second compound are a combination that forms an exciplex, The third compound is a compound represented by the following general formula (G2): 【Chemistry 2】 (However, in the above general formula (G2), R １ ~R １０ and R ２１ ~R ２４ each independently represents one of hydrogen, an alkyl group having from 3 to 10 carbon atoms, and a substituted or unsubstituted cycloalkyl group having from 3 to 10 carbon atoms; X １ ~X ６ each independently represents any one of an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, and a cycloalkyl group having 7 to 10 carbon atoms and having a crosslinked structure.

8. In claim 7, The R ２１ ~R ２４ A light-emitting device in which the electrons are hydrogen.

9. In claim 7 or claim 8, The X １ ~X ６ is a cycloalkyl group having 3 to 12 carbon atoms.

10. In any one of claims 7 to 9, The X １ ~X ６ A light-emitting device in which

11. In any one of claims 1 to 10, The R １ ~R １０ A light-emitting device in which the electrons are hydrogen.

12. In any one of claims 1 to 11, The light-emitting device, wherein one of the first compound and the second compound is a phosphorescent material.

13. In any one of claims 1 to 11, The light-emitting device, wherein one of the first compound and the second compound is a TADF material.

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