Light-emitting device, electronic appliance, and illumination device

Abstract

To provide a light-emitting device with high luminous efficiency and high reliability.SOLUTION: A light-emitting device includes first and second light-emitting units. The first light-emitting unit includes a first light-emitting layer. The first light-emitting layer includes a first material and a second material. The first material has a function of converting triplet excited energy into light emission. The second material has a function of converting singlet excited energy into light emission and includes a luminophore and five or more protective groups. The luminophore is a condensed aromatic ring or a condensed heterocyclic aromatic ring. The five or more protective groups independently include any one of an alkyl group with 1 or more and 10 or less carbon atoms, a substituted or non-substituted cycloalkyl group with 3 or more and 10 or less carbon atoms, and a trialkylsilyl group with 3 or more and 12 or less carbon atoms. Light emission is obtained from the second material.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] One embodiment of the present invention relates to a light-emitting device, 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 specifically, examples of the technical field of one embodiment of the present invention disclosed in this specification include a semiconductor device, a display device, a liquid crystal display device, a light-emitting device, a lighting device, a power storage device, a memory device, a driving method thereof, or a manufacturing method 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 the electrodes of this device, light is emitted from the light-emitting substance.

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

[0005] In the case of a light-emitting device in which an organic compound is used as a light-emitting substance and an EL layer containing the light-emitting organic compound is provided between a pair of electrodes, applying a voltage between the pair of electrodes causes electrons from the cathode and holes from the anode to be injected into the light-emitting EL layer, respectively, causing a current to flow. The injected electrons and holes are then recombined to excite the light-emitting organic compound, and light can be emitted from the excited light-emitting organic compound.

[0006] The types of excited states that organic compounds can form include singlet excited states (S * ) and triplet excited states (T * ), where 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 in a light-emitting device is S * :T * =1:3. Therefore, light-emitting devices using compounds that emit phosphorescence (phosphorescent materials) can achieve higher luminous efficiency than light-emitting devices using compounds that emit fluorescence (fluorescent materials). Therefore, in recent years, there has been active development of light-emitting devices using phosphorescent materials that can convert the energy of triplet excited states into light emission.

[0007] Among light-emitting devices using phosphorescent materials, particularly for light-emitting devices that emit blue light, it is difficult to develop stable compounds with high triplet excitation energy levels, so blue phosphorescent light-emitting devices have not yet been put to practical use. Therefore, light-emitting devices using more stable fluorescent materials are being developed, and methods for improving the luminous efficiency of light-emitting devices using fluorescent materials (fluorescent light-emitting devices) are being explored.

[0008] In addition to phosphorescent materials, thermally activated delayed fluorescence (TADF) materials are known as materials capable of converting part or all of the energy of a triplet excited state into light emission. In thermally activated delayed fluorescence materials, a singlet excited state is generated from the triplet excited state by reverse intersystem crossing, and the singlet excited state is converted into light emission.

[0009] In order to increase the luminous efficiency of a light-emitting device using a thermally activated delayed fluorescent material, it is important that the thermally activated delayed fluorescent material not only efficiently generates a singlet excited state from a triplet excited state, but also efficiently emits light from the singlet excited state, i.e., has a high fluorescence quantum yield. However, it is difficult to design a light-emitting material that satisfies both of these requirements at the same time.

[0010] Also, in a light-emitting device having a thermally activated delayed fluorescent material and a fluorescent material, a method has been proposed in which the singlet excitation energy of the thermally activated delayed fluorescent material is transferred to the fluorescent material to obtain light emission from the fluorescent material (Patent Document 1). That is, a light-emitting device has been proposed in which a thermally activated delayed fluorescent material is used as a host material and a fluorescent material is used as a guest material. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] JP 2014-45179 A [Patent Document 2] JP 2015-109407 A Summary of the Invention [Problem to be solved by the invention]

[0012] Multicolor light-emitting devices, such as white light-emitting devices, are expected to be used in displays and other applications. A preferred structure for a multicolor light-emitting device is one that includes multiple light-emitting layers, each of which emits a different color of light, between a pair of electrodes. In this case, from the standpoint of reliability and color purity, there is a demand for the development of a multicolor light-emitting device that combines multiple fluorescent light-emitting layers or a multicolor light-emitting device that combines a phosphorescent light-emitting layer and a fluorescent light-emitting layer.

[0013] As a method for improving the luminous efficiency of a fluorescent-emitting layer in a light-emitting device, for example, in a fluorescent-emitting layer having a fluorescent material as a host material and a guest material, a method is given in which the triplet excitation energy of the host material is converted to singlet excitation energy, and then the singlet excitation energy is transferred to the fluorescent material. However, the process in which the triplet excitation energy of the host material is converted to singlet excitation energy competes with the process in which the triplet excitation energy is deactivated. Therefore, the triplet excitation energy of the host material may not be sufficiently converted to singlet excitation energy. As a route in which the triplet excitation energy is deactivated, for example, a deactivation route in which the triplet excitation energy of the host material moves to the lowest triplet excitation energy level (T1 level) of the fluorescent material in the fluorescent-emitting layer is considered. Since the energy transfer by this deactivation route does not contribute to light emission, it leads to a decrease in the luminous efficiency of the fluorescent-emitting layer. This deactivation pathway can be suppressed by reducing the concentration of the fluorescent material, which is the guest material; however, at the same time, the rate of energy transfer from the host material to the fluorescent material to the singlet excited state also decreases, making quenching by degradation products and impurities more likely to occur. This leads to a decrease in the brightness of the light-emitting device, leading to a decrease in reliability. In addition, when two types of fluorescent-emitting layers are close to each other, the relationship between the T1 levels of the materials in each fluorescent-emitting layer becomes important.

[0014] In view of the above, one aspect of the present invention aims to suppress the transfer of triplet excitation energy of a host material to the T1 level of a fluorescent material in a fluorescent-emitting layer, efficiently convert the triplet excitation energy of the host material into singlet excitation energy of a fluorescent material, and thereby increase the fluorescent emission efficiency of a light-emitting device and improve its reliability. Another object of the present invention is to increase the emission efficiency of each of a plurality of fluorescent-emitting layers in a light-emitting device having the plurality of fluorescent-emitting layers.

[0015] Another object of one embodiment of the present invention is to provide a light-emitting device with high emission efficiency. Another object of one embodiment of the present invention is to provide a light-emitting device with high reliability. 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.

[0016] 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 the above are obvious from the description of the specification, etc., and problems other than the above can be extracted from the description of the specification, etc. [Means for solving the problem]

[0017] One embodiment of the present invention is a light-emitting device having a first light-emitting unit, a second light-emitting unit, and a charge generation layer between a pair of electrodes, the first light-emitting unit having a first light-emitting layer, the first light-emitting layer having a first material and a second material, the first material having a function of converting triplet excitation energy into light emission, the second material having a function of converting singlet excitation energy into light emission and having a luminophore and five or more protecting groups, the luminophore is a fused aromatic ring or a fused heteroaromatic ring, and the five or more protecting groups each independently have any one of an alkyl group having from 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having from 3 to 10 carbon atoms, or a trialkylsilyl group having from 3 to 12 carbon atoms, and light emission is obtained from the second material.

[0018] In the above-mentioned structure, it is preferable that at least four of the five or more protecting groups are each independently any one of an alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 12 carbon atoms.

[0019] Another embodiment of the present invention is a light-emitting device including a first light-emitting layer and a second light-emitting layer between a pair of electrodes, the first light-emitting layer including a first material and a second material, the first material having a function of converting triplet excitation energy into light emission, the second material having a function of converting singlet excitation energy into light emission, and including a luminophore and at least four protecting groups, the luminophore being a fused aromatic ring or a fused heteroaromatic ring, the four protecting groups not being directly bonded to the fused aromatic ring or the fused heteroaromatic ring, and the four protecting groups each independently being any one of an alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, or a trialkylsilyl group having 3 to 12 carbon atoms, and light emission is obtained from the second material.

[0020] Another embodiment of the present invention is a light-emitting device including a first light-emitting unit, a second light-emitting unit, and a charge generation layer between a pair of electrodes, the first light-emitting unit including a first light-emitting layer, the first light-emitting layer including a first material and a second material, the first material having a function of converting triplet excitation energy into light emission, the second material having a function of converting singlet excitation energy into light emission, the second material having a luminophore and two or more diarylamino groups, the luminophore being a fused aromatic ring or a fused heteroaromatic ring, the fused aromatic ring or the fused heteroaromatic ring being bonded to the two or more diarylamino groups, the aryl groups in the two or more diarylamino groups each independently having at least one protecting group, and the protecting group being any one of an alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 12 carbon atoms, and light emission is obtained from the second material.

[0021] Another embodiment of the present invention is a light-emitting device including a first light-emitting unit, a second light-emitting unit, and a charge generation layer between a pair of electrodes, the first light-emitting unit including a first light-emitting layer, the first light-emitting layer including a first material and a second material, the first material having a function of converting triplet excitation energy into light emission, the second material having a function of converting singlet excitation energy into light emission, and including a luminophore and two or more diarylamino groups, the luminophore being a fused aromatic ring or a fused heteroaromatic ring, the fused aromatic ring or the fused heteroaromatic ring being bonded to the two or more diarylamino groups, the aryl groups in the two or more diarylamino groups each independently having at least two protecting groups, and the protecting groups being any one of an alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 12 carbon atoms, and light emission is obtained from the second material.

[0022] In the above structure, the diarylamino group is preferably a diphenylamino group.

[0023] Another embodiment of the present invention is a light-emitting device including a first light-emitting unit, a second light-emitting unit, and a charge generation layer between a pair of electrodes, the first light-emitting unit including a first light-emitting layer, the first light-emitting layer including a first material and a second material, the first material having a function of converting triplet excitation energy into light emission, the second material having a function of converting singlet excitation energy into light emission, and including a luminophore and a plurality of protecting groups, the luminophore being a fused aromatic ring or a fused heteroaromatic ring, each of the plurality of protecting groups independently being any one of an alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, or a trialkylsilyl group having 3 to 12 carbon atoms, at least one of the atoms constituting the plurality of protecting groups being located directly above one surface of the fused aromatic ring or the fused heteroaromatic ring and at least one of the atoms constituting the plurality of protecting groups being located directly above the other surface of the fused aromatic ring or the fused heteroaromatic ring, and light emission being obtained from the second material.

[0024] Another embodiment of the present invention is a light-emitting device including a first light-emitting unit, a second light-emitting unit, and a charge generation layer between a pair of electrodes, the first light-emitting unit including a first light-emitting layer, the first light-emitting layer including a first material and a second material, the first material having a function of converting triplet excitation energy into light emission, the second material having a function of converting singlet excitation energy into light emission, and including a luminophore and two or more diphenylamino groups, the luminophore being a fused aromatic ring or a fused heteroaromatic ring, the fused aromatic ring or the fused heteroaromatic ring being bonded to two or more diphenylamino groups, the phenyl groups in the two or more diphenylamino groups each independently have protecting groups at the 3-position and the 5-position, and the protecting groups each independently have any one of an alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, or a trialkylsilyl group having 3 to 12 carbon atoms, and light emission is obtained from the second material.

[0025] In the above structure, the alkyl group is preferably a branched chain alkyl group.

[0026] In the above structure, it is preferable that the branched alkyl group has a quaternary carbon.

[0027] In the above structure, the condensed aromatic ring or the condensed heteroaromatic ring preferably contains any one of naphthalene, anthracene, fluorene, chrysene, triphenylene, pyrene, tetracene, perylene, coumarin, quinacridone, and naphthobisbenzofuran.

[0028] In the above structure, it is preferable that the second light-emitting unit has a second light-emitting layer, the second light-emitting layer has a second phosphorescent material, and light emission originating from the second phosphorescent material is obtained, and it is more preferable that the peak wavelength in the emission spectrum of the second phosphorescent material is longer than the peak wavelength in the emission spectrum of the second material.

[0029] In the above structure, the first material is preferably a first phosphorescent material.

[0030] In the above structure, the first material is preferably a compound exhibiting thermally activated delayed fluorescence.

[0031] Another embodiment of the present invention is a display device having the light-emitting device of any of the above configurations and at least one of a color filter or a transistor. Another embodiment of the present invention is an electronic device having the display device and at least one of a housing or a display unit. Another embodiment of the present invention is a lighting device having the light-emitting device of any of the above configurations and at least one of a housing or a touch sensor. Another embodiment of the present invention includes not only a light-emitting device having a light-emitting device, but also an electronic device having a light-emitting device. Therefore, the light-emitting device in this specification refers to an image display device or a light source (including a lighting device). In addition, the light-emitting device may include a display module in which a connector, such as an FPC (Flexible Printed Circuit) or a TCP (Tape Carrier Package), is attached to a light-emitting device, a display module in which a printed wiring board is provided at the end of the TCP, or a display module in which an IC (Integrated Circuit) is directly mounted on a light-emitting device by a COG (Chip On Glass) method. Effect of the Invention

[0032] 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.

[0033] Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. Note that effects other than these are self-evident from the description in the specification, drawings, claims, etc., and it is possible to extract effects other than these from the description in the specification, drawings, claims, etc. [Brief description of the drawings]

[0034] [Figure 1] 1A and 1B are schematic cross-sectional views of a light-emitting device according to one embodiment of the present invention. [Diagram 2] FIG. 2A 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 FIG. 2B is a diagram illustrating the correlation between energy levels. [Diagram 3] 3A and 3B 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, respectively. [Figure 4] 4A and 4B are structural formulas and ball-and-stick diagrams of guest materials used in light-emitting devices according to embodiments of the present invention. [Diagram 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 to 5D are diagrams illustrating the correlation between energy levels of the light-emitting layer of a light-emitting device according to one embodiment of the present invention. [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, Fig. 6B and Fig. 6C are diagrams illustrating the correlation between the energy levels of the light-emitting layer of a light-emitting device according to one embodiment of the present invention. [Figure 7] Fig. 7A 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 Fig. 7B and Fig. 7C are diagrams illustrating the correlation between the energy levels of the light-emitting layer of a light-emitting device according to one embodiment of the present invention. [Figure 8] Fig. 8A 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 Fig. 8B is a diagram illustrating the correlation between energy levels of the light-emitting layer of a light-emitting device according to one embodiment of the present invention. [Figure 9]9A 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. 9B and 9C are diagrams illustrating the correlation between the energy levels of the light-emitting layer of a light-emitting device according to one embodiment of the present invention. [Figure 10] Fig. 10A 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 Fig. 10B and Fig. 10C are diagrams illustrating the correlation between the energy levels of the light-emitting layer of a light-emitting device according to one embodiment of the present invention. [Figure 11] 11A and 11B are a top view and a schematic cross-sectional view illustrating a display device of one embodiment of the present invention. [Figure 12] 12A and 12B are cross-sectional schematic diagrams illustrating a display device of one embodiment of the present invention. [Figure 13] 13A and 13B are schematic cross-sectional views illustrating a display device according to one embodiment of the present invention. [Figure 14] 14A to 14D are perspective views illustrating a display module of one embodiment of the present invention. [Figure 15] 15A to 15C are diagrams illustrating electronic devices of one embodiment of the present invention. [Figure 16] 16A and 16B are perspective views illustrating a display device of one embodiment of the present invention. [Figure 17] FIG. 17 illustrates a lighting device according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] Hereinafter, the embodiment 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 can be made in the form and details 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 embodiment shown below.

[0036] In addition, for ease of understanding, the position, size, range, etc. of each component shown in the drawings, etc. may not represent the actual position, size, range, etc. Therefore, the disclosed invention is not necessarily limited to the position, size, range, etc. disclosed in the drawings, etc.

[0037] In addition, in this specification, ordinal numbers such as first, second, etc. are used for convenience and may not indicate the order of steps or stacking. Therefore, for example, "first" can be appropriately replaced with "second" or "third" to explain. In addition, the ordinal numbers described in this specification may not match the ordinal numbers used to specify one embodiment of the present invention.

[0038] In addition, in this specification and the like, when describing the configuration of the invention using drawings, the same reference numerals may be used in common between different drawings.

[0039] In addition, in this specification and the like, the term "film" and the term "layer" can be interchanged. For example, the term "conductive layer" may be changed to the term "conductive film." Or, for example, the term "insulating film" may be changed to the term "insulating layer."

[0040] In the present specification and the like, the singlet excited state (S * ) is a singlet state with excitation energy. The S1 level is the lowest singlet excited energy level, and is the lowest singlet excited state (S1 state) excitation energy level. The triplet excited state (T *) refers to a triplet state having an excitation energy. The T1 level is the lowest level of triplet excitation energy levels, and refers to the lowest triplet excitation energy level (T1 state). In this specification and the like, even when simply referring to a singlet excitation state and a singlet excitation energy level, it may refer to an S1 state and an S1 level. Even when referring to a triplet excitation state and a triplet excitation energy level, it may refer to a T1 state and a T1 level.

[0041] In this specification and the like, 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 one of the compounds that can convert triplet excited energy into visible light.

[0042] In the present specification, the blue wavelength region is from 400 nm to less than 490 nm, and the blue emission has at least one emission spectrum peak in this wavelength region. The green wavelength region is from 490 nm to less than 580 nm, and the green emission has at least one emission spectrum peak in this wavelength region. The red wavelength region is from 580 nm to 680 nm, and the red emission has at least one emission spectrum peak in this wavelength region.

[0043] In the present specification and the like, the light-emitting layer is a layer containing one or more fluorescent materials or phosphorescent materials. The fluorescent light-emitting layer is a layer from which light emission having fluorescent emission is obtained, and the phosphorescent light-emitting layer is a layer from which light emission having phosphorescent emission is obtained. When a current is passed through the light-emitting device, light is emitted from the light-emitting device originating from the fluorescent material or phosphorescent material contained in the light-emitting layer.

[0044] (Embodiment 1) In this embodiment, a light-emitting device of one embodiment of the present invention will be described below with reference to FIGS. 1A and 1B. FIG.

[0045] <Light-emitting device configuration example 1> 1A and 1B are schematic cross-sectional views of light emitting device 150 and light emitting device 152. FIG.

[0046] The light-emitting device 150 and the light-emitting device 152 have an electrode 101, an electrode 102, an electrode 103, and an electrode 104 on a substrate 200. At least a light-emitting unit 106, a light-emitting unit 108, and an electron injection layer 140 are provided between the electrodes 101 and 102, between the electrodes 102 and 103, and between the electrodes 102 and 104. 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 configuration or different configurations.

[0047] 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. 1A and FIG. 1B, when a voltage is applied so that the potential of electrode 102 is higher than the potential of electrode 101, charge generation layer 115 injects electrons into light-emitting unit 106 and injects holes into light-emitting unit 108.

[0048] The light-emitting unit 106 includes, for example, a hole injection layer 111, a hole transport layer 112, a light-emitting layer 130, and an electron transport layer 113. The light-emitting unit 108 includes, for example, a hole injection layer 116, a hole transport layer 117, a light-emitting layer 170, an electron transport layer 118, and an electron injection layer 119.

[0049] 1A and 1B, the electron injection layer 140 is preferably adjacent to the electron transport layer 113 and provided between the light-emitting unit 108 and the electron transport layer 113. Also, as shown in Fig. 1A and 1B, the charge generation layer 115 is preferably adjacent to the electron injection layer 140 and provided between the electron injection layer 140 and the light-emitting unit 108. With this configuration, electrons can be efficiently transported to the light-emitting unit 106.

[0050] In the present embodiment, the electrodes 101, 103, and 104 are described as an anode, and the electrode 102 is described as a cathode, but the configuration of the light-emitting device 150 and the light-emitting device 152 is not limited to this. That is, the electrodes 101, 103, and 104 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 light-emitting unit 106 may be stacked in the order of the hole injection layer 111, the hole transport layer 112, the light-emitting layer 130, the electron transport layer 113, and the electron injection layer 140 from the anode side, and the light-emitting unit 108 may be stacked in the order of the hole injection layer 116, the hole transport layer 117, the light-emitting layer 170, the electron transport layer 118, and the electron injection layer 119 from the anode side.

[0051] In addition, the configuration of light-emitting device 150 and light-emitting device 152 is not limited to the configuration shown in Figures 1A and 1B, and each of them has at least light-emitting layer 130, light-emitting layer 170, charge generation layer 115, and electron injection layer 140, and may or may not have hole injection layer 111, hole injection layer 116, hole transport layer 112, hole transport layer 117, electron transport layer 113, electron transport layer 118, and electron injection layer 119.

[0052] In addition, a layer corresponding to the function may be formed between the pair of electrodes, and is not limited thereto. That is, a layer having a function of reducing the hole or electron injection barrier, improving the hole or electron transportability, inhibiting the hole or electron transportability, or suppressing the quenching phenomenon caused by the electrodes may be formed between the pair of electrodes.

[0053] In addition, when the anode side surface of the light-emitting unit is in contact with the charge generation layer 115, as in the case of the light-emitting unit 108, the charge generation layer 115 may also serve as the hole injection layer of the light-emitting unit 108, and therefore, it may not be necessary to provide a hole injection layer for the light-emitting unit.

[0054] 1A and 1B, a light-emitting device having two light-emitting units has been described, but the present invention can be applied to a light-emitting device having three or more light-emitting units stacked together. As shown in light-emitting device 150 and light-emitting device 152, by disposing a plurality of light-emitting units between a pair of electrodes and separating them with a charge generating layer, a light-emitting device that can emit light with high brightness while keeping the current density low and has a long life can be realized. Also, a light-emitting device with low power consumption can be realized.

[0055] In the light-emitting device 150, the electrodes 101, 103, and 104 have a function of reflecting visible light, and the electrode 102 has a function of transmitting visible light. In the light-emitting device 152, the electrodes 101, 103, and 104 have a function of transmitting visible light, and the electrode 102 has a function of reflecting visible light.

[0056] Therefore, light emitted by the light-emitting device 150 is emitted to the outside through the electrode 102, and light emitted by the light-emitting device 152 is emitted to the outside through the electrodes 101, 103, and 104. However, one embodiment of the present invention is not limited thereto, and the light-emitting device may extract light both above and below the substrate 200 on which the light-emitting device is formed.

[0057] The electrode 101 includes a conductive layer 101a and a conductive layer 101b on and in contact with the conductive layer 101a. The electrode 103 includes a conductive layer 103a and a conductive layer 103b on and in contact with the conductive layer 103a. The electrode 104 includes a conductive layer 104a and a conductive layer 104b on and in contact with the conductive layer 104a.

[0058] The conductive layer 101b, the conductive layer 103b, and the conductive layer 104b have a function of transmitting visible light. In the light-emitting device 150, the conductive layer 101a, the conductive layer 103a, and the conductive layer 104a have a function of reflecting visible light. In the light-emitting device 152, the conductive layer 101a, the conductive layer 103a, and the conductive layer 104a have a function of transmitting visible light.

[0059] The light-emitting device 150 shown in Fig. 1A and the light-emitting device 152 shown in Fig. 1B have partition walls 145 between a region 222B sandwiched between the electrodes 101 and 102, a region 222G sandwiched between the electrodes 102 and 103, and a region 222R sandwiched between the electrodes 102 and 104. The partition walls 145 have insulating properties. The partition walls 145 cover the ends of the electrodes 101, 103, and 104, and have openings that overlap the electrodes. By providing the partition walls 145, the electrodes on the substrate 200 in each region can be separated into islands.

[0060] In addition, in Figures 1A and 1B, the hole injection layer 111, the hole injection layer 116, the hole transport layer 112, the hole transport layer 117, the light-emitting layer 130, the light-emitting layer 170, the electron transport layer 113, the electron transport layer 118, the electron injection layer 119, the charge generation layer 115, and the electrode 102 are illustrated as being provided in common to each region without being separated from each other, but they may be provided separately from each other in each region.

[0061] In the light-emitting device 150 and the light-emitting device 152 according to an embodiment of the present invention, a voltage is applied between a pair of electrodes (electrodes 101 and 102) in the region 222B, between a pair of electrodes (electrodes 102 and 103) in the region 222G, and between a pair of electrodes (electrodes 102 and 104) in the region 222R, whereby electrons are injected from the cathode into the electron injection layer 119 and holes are injected from the anode into the hole injection layer 111, causing a current to flow. Also, electrons are injected from the charge generation layer 115 into the electron injection layer 140, and holes are injected from the charge generation layer 115 into the hole injection layer 116. Then, the injected carriers (electrons and holes) are recombined to form excitons. When carriers (electrons and holes) recombine in the light-emitting layers 130 and 170 containing the light-emitting material to form excitons, the light-emitting material contained in the light-emitting layers 130 and 170 enters an excited state, and light is emitted from the light-emitting material.

[0062] Light-emitting layer 130 and light-emitting layer 170 preferably contain one or more light-emitting materials selected from the group consisting of purple, blue, blue-green, green, yellow-green, yellow, yellow-orange, orange, and red light-emitting materials.

[0063] The light-emitting layer 130 and the light-emitting layer 170 may have a two-layer laminated structure. By using two types of light-emitting materials, a first compound and a second compound, each of which has a function of exhibiting different colors, in the two light-emitting layers, it is possible to simultaneously obtain multiple lights. In particular, it is preferable to select the light-emitting material used in each light-emitting layer so that the light emitted by the light-emitting layer 130 and the light-emitting layer 170 is white or a color close to white.

[0064] Furthermore, the light-emitting layer 130 and the light-emitting layer 170 may have a configuration in which three or more layers are laminated, and may include a layer that does not contain a light-emitting material.

[0065] Furthermore, the light emitting device 150 and the light emitting device 152 have a substrate 220 having optical elements 224B, 224G, and 224R in the direction in which the light emitted from the region 222B, the region 222G, and the region 222R is extracted, respectively. The light emitted from each region is emitted to the outside of the light emitting device through each optical element. That is, the light emitted from the region 222B is emitted through the optical element 224B, the light emitted from the region 222G is emitted through the optical element 224G, and the light emitted from the region 222R is emitted through the optical element 224R.

[0066] In addition, optical element 224B, optical element 224G, and optical element 224R have a function of selectively transmitting light of a specific color from the incident light. For example, the light emitted from region 222B via optical element 224B is blue light, the light emitted from region 222G via optical element 224G is green light, and the light emitted from region 222R via optical element 224R is red light.

[0067] 1A and 1B, the light emitted from each region via each optical element is shown by a dashed arrow as blue (B), green (G), and red (R) light. Light-emitting device 150 shown in Fig. 1A is a top-emission type light-emitting device, and light-emitting device 152 shown in Fig. 1B is a bottom-emission type light-emitting device.

[0068] In addition, a light shielding layer 223 is provided between each optical element. The light shielding layer 223 has a function of blocking light emitted from an adjacent region. Note that a configuration may be adopted in which the light shielding layer 223 is not provided. Also, a configuration may be adopted in which one or more of the optical element 224B, the optical element 224G, and the optical element 224R are not provided. By adopting a configuration in which the optical element 224B, the optical element 224G, and the optical element 224R are not provided, it is possible to increase the extraction efficiency of light emitted from the light emitting device.

[0069] The charge generation layer 115 can be formed from a material in which an electron acceptor is added to a hole transporting material, or a material in which an electron donor is added to an electron transporting material.

[0070] Here, when a light-emitting device having a plurality of light-emitting units as shown in FIG. 1A and FIG. 1B is applied to a multicolor light-emitting device, a combination of a fluorescent light-emitting unit and a phosphorescent light-emitting unit is considered. In the light-emitting device of one embodiment of the present invention, a fluorescent light-emitting unit using a fluorescent light-emitting layer containing a fluorescent material having a protecting group, which will be described later, is described as a fluorescent light-emitting unit. Hereinafter, a case where a fluorescent material having a protecting group is applied to the light-emitting layer 130 will be described, but a fluorescent material having a protecting group may be applied to the light-emitting layer 170. The light-emitting device of one embodiment of the present invention is a light-emitting device in which at least one of the light-emitting layer 130 and the light-emitting layer 170 is a fluorescent light-emitting layer containing a fluorescent material having a protecting group. Therefore, the configuration of the light-emitting layer 130 described below may be used for the light-emitting layer 170, and the configuration of the light-emitting layer 170 may be used for the light-emitting layer 130.

[0071] <Light Emitting Mechanism of the Light Emitting Layer 130> Next, the light emitting mechanism of the light emitting layer 130, which is a fluorescent light emitting layer, will be described below.

[0072] In the light-emitting device 150 and the light-emitting device 152 according to one embodiment of the present invention, a voltage is applied between a pair of electrodes (electrodes 101 and 102), whereby electrons are injected from the cathode and holes are injected from the anode into the light-emitting unit 106 and the light-emitting unit 108, respectively, and a current flows. Among excitons generated by recombination of carriers (electrons and holes), the ratio of singlet excitons to triplet excitons (hereinafter, exciton generation probability) is 1:3 due to statistical probability. That is, the rate at which singlet excitons are generated is 25%, and the rate at which triplet excitons are generated is 75%. Therefore, it is important to make triplet excitons contribute to light emission in order to improve the light-emitting efficiency of the light-emitting device. Therefore, it is preferable to use a material having a function of converting triplet excitation energy into light emission for the light-emitting layer 130.

[0073] Phosphorescent materials are examples of materials that have the function of converting triplet excitation energy into light emission. In this specification and the like, a phosphorescent material refers to a compound that exhibits phosphorescence and does not exhibit fluorescence at any temperature range from low temperature (e.g., 77 K) to room temperature (i.e., 77 K to 313 K). The phosphorescent material preferably has a metal element with large spin-orbit interaction, specifically a transition metal element, and particularly preferably has a platinum group element (ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), or platinum (Pt)), and among these, it is preferable to have iridium. By having iridium, the transition probability related to the direct transition between the singlet ground state and the triplet excited state can be increased, which is preferable.

[0074] In addition, TADF materials can be cited as materials that have the function of converting triplet excitation energy into light emission. TADF materials are materials that have a small difference between the S1 and T1 levels and can convert triplet excitation energy into singlet excitation energy by reverse intersystem crossing. Therefore, triplet excitation energy can be upconverted to singlet excitation energy by a small amount of thermal energy (reverse intersystem crossing), and a singlet excited state can be efficiently generated. In addition, exciplexes (also called exciplexes) that form an excited state with two types of substances have an extremely small difference between the S1 and T1 levels and function as TADF materials that can convert triplet excitation energy into singlet excitation energy.

[0075] As an index of the T1 level, a phosphorescence spectrum observed at a low temperature (e.g., 10 K) may be used. As a TADF material, when a tangent line is drawn at the short wavelength side of the fluorescence spectrum at room temperature or a low temperature, the energy of the wavelength of the extrapolated line is defined as the S1 level, and a tangent line is drawn at the short wavelength side of the phosphorescence spectrum, and the energy of the wavelength of the extrapolated line is defined as the T1 level, the difference between S1 and T1 is preferably 0.2 eV or less.

[0076] In addition, examples of materials having a function of converting triplet excitation energy into luminescence include nanostructures of transition metal compounds having a perovskite structure. In particular, nanostructures of metal halide perovskites are preferred. As the nanostructures, nanoparticles and nanorods are preferred.

[0077] FIG. 2A is a schematic cross-sectional view showing 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 a compound 131 and a compound 132. The compound 131 has a function of converting triplet excitation energy into light emission, and the compound 132 has a function of converting singlet excitation energy into light emission. Since fluorescent materials are highly stable, it is preferable to use a fluorescent material as the compound 132 in order to obtain a highly reliable light-emitting device. Since the compound 131 has a function of converting triplet excitation energy into light emission, it is preferable that carrier recombination occurs in the compound 131 in order to obtain a light-emitting device with high luminous efficiency. Therefore, it is preferable that both the singlet excitation energy and triplet excitation energy of the exciton generated by the recombination of carriers in the compound 131 are finally transferred to the singlet excitation state of the compound 132, and the compound 132 emits light. Here, in the light-emitting layer 130, the compound 131 is an energy donor, and the compound 132 is an energy acceptor. 2A and 2B, the light-emitting layer 130 is a fluorescent layer containing compound 131 as a host material and compound 132 as a guest material. That is, in FIG. 2A and 2B, the host material functions as an energy donor and the guest material functions as an energy acceptor. Furthermore, the light-emitting layer 130 can emit light derived from compound 132, which is a guest material.

[0078] <Configuration Example 1 of Light-Emitting Layer 130> 2B shows an example of the correlation of energy levels in the light-emitting layer of the light-emitting device according to one embodiment of the present invention. In this configuration example, a TADF material is used for Compound 131.

[0079] 2B shows the correlation between the energy levels of the compound 131 and the compound 132 in the light-emitting layer 130. The notations and symbols in FIG. 2B 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

[0080] Here, we focus on the triplet excitation energy of compound 131 generated by current excitation. Compound 131 has TADF properties. Therefore, compound 131 has the function of converting triplet excitation energy into singlet excitation energy by upconversion (Fig. 2B, Route A1). The singlet excitation energy of compound 131 can be rapidly transferred to compound 132 (Fig. 2B, Route A2). At this time, S C1 ≧S G Specifically, a tangent line is drawn at the short wavelength side of the fluorescence spectrum of compound 131, and the energy of the wavelength of the extrapolated line is S C1 The energy of the wavelength of the absorption edge of the absorption spectrum of compound 132 is S G When this is done, S C1 ≧S G It is preferable that the compound 131 is a material having TADF properties, and therefore, S C1 and T C1 is very small. Therefore, S C1 ≧T C1 ≧S G It could be.

[0081] The triplet excitation energy generated in compound 131 is transferred to the S1 level of the guest material compound 132 via the above-mentioned routes A1 and A2, and compound 132 emits light, thereby improving the luminous efficiency of the fluorescent light-emitting device. In route A2, compound 131 functions as an energy donor, and compound 132 functions as an energy acceptor.

[0082] Here, in the light-emitting layer 130, the compounds 131 and 132 are mixed. Therefore, a process (route A3 in FIG. 2B) in which the triplet excitation energy of the compound 131 is converted to the triplet excitation energy of the compound 132 in competition with the above-mentioned routes A1 and A2 may occur. Since the compound 132 is a fluorescent material, the triplet excitation energy of the compound 132 does not contribute to light emission. In other words, if the energy transfer of route A3 occurs, the light-emitting efficiency of the light-emitting device will decrease. In reality, T C1 From T G The energy transfer to T of compound 132 (route A3) is not direct. G Energy is transferred once to a triplet excited state higher than T, and then internal conversion occurs. G However, this process is omitted in the figure. G The deactivation process for all of them is similar.

[0083] Here, the Förster mechanism (dipole-dipole interaction) and the Dexter mechanism (electron exchange interaction) are known as intermolecular energy transfer mechanisms. Since the energy acceptor, compound 132, is a fluorescent material, the Dexter mechanism is dominant in the energy transfer of route A3. In general, 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, that is, the distance between the energy donor and the energy acceptor.

[0084] In addition, the singlet excited energy level of compound 131 (S C1 ) to obtain the triplet excited energy level (T G ) is not shown in the figure because it is unlikely to be the main energy transfer process since a direct transition from the singlet ground state to the triplet excited state in compound 132 is prohibited.

[0085] T in Figure 2B Gis often an energy level derived from the luminophore in the energy acceptor. Therefore, in order to suppress route A3 in more detail, it is important to increase the distance between the energy donor and the luminophore possessed by the energy acceptor. A common method for increasing the distance between the luminophore possessed by the energy donor and the energy acceptor is to reduce the concentration of the energy acceptor in the mixed film of these compounds. However, when the concentration of the energy acceptor in the mixed film is reduced, 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 is suppressed. In that case, since route A2 is based on the Förster mechanism, problems such as a decrease in the luminous efficiency and reliability of the light-emitting device occur.

[0086] Therefore, the present inventors have found that the above-mentioned decrease in luminous efficiency and decrease in reliability can be suppressed by using, as an energy acceptor, a fluorescent material having a protecting group for increasing the distance from the energy donor, and that the decrease in luminous efficiency of the phosphorescent-emitting layer, which occurs when a phosphorescent-emitting layer and a fluorescent-emitting layer are combined, can also be suppressed.

[0087] <Concept of fluorescent materials having protecting groups> FIG. 3A shows a conceptual diagram of a typical fluorescent material that does not have a protecting group dispersed as a guest material in a host material, and FIG. 3B shows a conceptual diagram of a fluorescent material that has a protecting group and is used in a light-emitting device according to one embodiment of the present invention dispersed as a guest material in a host material. The host material may be read as an energy donor, and the guest material may be read as an energy acceptor. Here, the protecting group has a function of increasing the distance between the luminophore and the host material. In FIG. 3A, the guest material 301 has a luminophore 310. The guest material 301 has a function as an energy acceptor. Meanwhile, in FIG. 3B, the guest material 302 has a luminophore 310 and a protecting group 320. In addition, in FIGS. 3A and 3B, the guest material 301 and the guest material 302 are surrounded by a host material 330. In Fig. 3A, since the distance between the luminophore and the host material is short, both energy transfer by the Förster mechanism (route A4 in Fig. 3A and Fig. 3B) and energy transfer by the Dexter mechanism (route A5 in Fig. 3A and Fig. 3B) can occur as energy transfer from the host material 330 to the guest material 301. When triplet excitation energy transfer from the host material to the guest material by the Dexter mechanism occurs and a triplet excited state of the guest material is generated, if the guest material is a fluorescent material, the triplet excitation energy is non-radiatively deactivated, which is one of the causes of a decrease in luminous efficiency.

[0088] 3B, the guest material 302 has a protecting group 320. This makes it possible to increase the distance between the luminophore 310 and the host material 330. This makes it possible to suppress energy transfer by the Dexter mechanism (route A5).

[0089] Here, in order for the guest material 302 to emit light, the Dexter mechanism is suppressed, and therefore the guest material 302 needs to receive energy from the host material 330 by the Förster mechanism. That is, it is preferable to efficiently utilize the energy transfer by the Förster mechanism while suppressing the energy transfer by the Dexter mechanism. It is known that the energy transfer by the Förster mechanism is also affected by the distance between the host material and the guest material. In general, when the distance between the host material 330 and the guest material 302 is 1 nm or less, the Dexter mechanism predominates, and when the distance is 1 nm or more and 10 nm or less, the Förster mechanism predominates. In general, when the distance between the host material 330 and the guest material 302 is 10 nm or more, energy transfer is unlikely to occur. Here, the distance between the host material 330 and the guest material 302 may be read as the distance between the host material 330 and the luminophore 310.

[0090] Therefore, it is preferable that the protecting group 320 extends from the luminophore 310 in a range of 1 nm to 10 nm. More preferably, it extends from 1 nm to 5 nm. With this configuration, it is possible to efficiently utilize the energy transfer by the Förster mechanism while suppressing the energy transfer by the Dexter mechanism from the host material 330 to the guest material 302. Therefore, it is possible to manufacture a light-emitting device having high light-emitting efficiency.

[0091] In order to increase the efficiency of energy transfer by the Förster mechanism (to improve the energy transfer rate), it is preferable to increase the concentration of the guest material 301 or 302 relative to the host material 330. However, when the concentration of the guest material increases, the energy transfer rate of the Dexter mechanism also increases, and the luminescence efficiency decreases. For this reason, it has been difficult to increase the concentration of the guest material. In a fluorescent light-emitting device in which a material having a function of converting triplet excitation energy into luminescence is used as a host material, a light-emitting device with a low guest material concentration of 1 wt% or less has been reported.

[0092] On the other hand, in the light-emitting device of one embodiment of the present invention, a guest material having a protecting group on the luminophore is used in the light-emitting layer. Therefore, energy transfer by the Förster mechanism can be efficiently utilized while suppressing energy transfer by the Dexter mechanism, and therefore the concentration of the guest material, which is an energy acceptor, can be increased. As a result, it is possible to achieve the inherently contradictory phenomenon of suppressing energy transfer by the Dexter mechanism while increasing the rate of energy transfer by the Förster mechanism. By increasing the rate of energy transfer by the Förster mechanism, the excitation lifetime of the energy acceptor in the light-emitting layer is shortened, and therefore the reliability of the light-emitting device can be improved. The concentration of the guest material is preferably 2 wt% to 30 wt% inclusive, more preferably 5 wt% to 20 wt% inclusive, and further preferably 5 wt% to 15 wt% inclusive, relative to the host material. With this configuration, the rate of energy transfer by the Förster mechanism can be increased, and therefore a light-emitting device with high emission efficiency can be obtained. Furthermore, by using a material having a function of converting triplet excitation energy into light emission as the host material, a fluorescent light-emitting device with high emission efficiency equivalent to that of a phosphorescent light-emitting device can be manufactured. In addition, since the luminous efficiency can be improved by using a highly stable fluorescent material, a highly reliable light-emitting device can be fabricated. Note that the above concentrations are those when the material that mainly emits light is used as a guest material and the material other than the guest material is used as a host material in the light-emitting layer.

[0093] In particular, the effect of the light-emitting device according to one embodiment of the present invention is not only the reliability improvement effect by simply using a highly stable fluorescent material. The above-mentioned energy transfer always competes with the quenching process caused by the influence of degradation products and impurities. If the quenching rate constant of the quenching process increases over time, the rate at which the light-emitting device emits light decreases. In other words, the luminance of the light-emitting device deteriorates. However, as described above, one embodiment of the present invention can suppress the energy transfer by the Dexter mechanism while increasing the energy transfer rate by the Förster mechanism compared to conventional light-emitting devices, thereby reducing the effect of competition with the quenching process and extending the life of the device.

[0094] Here, the luminophore refers to an atomic group (skeleton) that causes light emission in a fluorescent material. The luminophore generally has a π bond, and preferably contains an aromatic ring, and preferably contains a condensed aromatic ring or a condensed heteroaromatic ring. In another embodiment, the luminophore can be regarded as an atomic group (skeleton) that contains an aromatic ring whose transition dipole vector exists on the ring plane. In addition, when one fluorescent material has a plurality of condensed aromatic rings or condensed heteroaromatic rings, the skeleton having the lowest S1 level among the plurality of condensed aromatic rings or condensed heteroaromatic rings may be considered as the luminophore of the fluorescent material. In addition, in the plurality of condensed aromatic rings or condensed heteroaromatic rings, the skeleton having the longest absorption edge at the longest wavelength may be considered as the luminophore of the fluorescent material. In addition, the luminophore of the fluorescent material may be predicted from the shape of the emission spectrum of each of the plurality of condensed aromatic rings or condensed heteroaromatic rings.

[0095] Examples of the condensed aromatic ring or condensed 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 they have a high fluorescence quantum yield.

[0096] In addition, the substituent used as a protecting group must have a triplet excitation energy level higher than the T1 level of the luminophore and the host material. Therefore, it is preferable to use a saturated hydrocarbon group. This is because the triplet excitation energy level of a substituent that does not have a π bond is high. In addition, a substituent that does not have a π bond has a low function of transporting carriers (electrons or holes). Therefore, a saturated hydrocarbon group can increase the distance between the luminophore and the host material without affecting the excited state or carrier transportability of the host material. In addition, in an organic compound that simultaneously has a substituent that does not have a π bond and a substituent that has a π conjugated system, there are many cases where a frontier orbital {HOMO (Highest Occupied Molecular Orbital, also called the highest occupied orbital) and LUMO (Lowest Unoccupied Molecular Orbital, also called the lowest unoccupied orbital)} exists on the side of the substituent that has the π conjugated system, and in particular, the luminophore often has a frontier orbital. As will be described later, the overlap of the HOMO and the LUMO of the energy donor and the energy acceptor is important for energy transfer by the Dexter mechanism. Therefore, by using a saturated hydrocarbon group as a protecting group, the distance between the frontier orbital of the host material, which is the energy donor, and the frontier orbital of the guest material, which is the energy acceptor, can be increased, and energy transfer via the Dexter mechanism can be suppressed.

[0097] Specific examples of the protective group include alkyl groups having 1 to 10 carbon atoms. In addition, since the protective group needs to increase the distance between the luminophore and the host material, bulky substituents are preferred. For this reason, alkyl groups having 3 to 10 carbon atoms, substituted or unsubstituted cycloalkyl groups having 3 to 10 carbon atoms, and trialkylsilyl groups having 3 to 12 carbon atoms can be preferably used. In particular, bulky branched alkyl groups are preferred as the alkyl group. In addition, the substituent is particularly preferred when it has a quaternary carbon, since it becomes a bulky substituent.

[0098] In addition, it is preferable that there are five or more protecting groups for one luminophore. With this configuration, the entire luminophore can be covered with the protecting group, so that the distance between the host material and the luminophore can be appropriately adjusted. In addition, although FIG. 3B shows the luminophore and the protecting group being directly bonded, it is more preferable that the protecting group is not directly bonded to the luminophore. For example, the protecting group may be bonded to the luminophore via a divalent or higher substituent such as an arylene group or an amino group. By bonding the protecting group to the luminophore via the substituent, the distance between the luminophore and the host material can be effectively increased. Therefore, when the luminophore and the protecting group are not directly bonded, if there are four or more protecting groups for one luminophore, the energy transfer by the Dexter mechanism can be effectively suppressed.

[0099] In addition, it is preferable that the divalent or higher substituent linking the luminophore and the protecting group is a substituent having a π-conjugated system. By adopting this structure, it is possible to adjust the physical properties of the guest material, such as the emission color, HOMO level, and glass transition point. It is preferable that the protecting group is arranged on the outermost side when the molecular structure is viewed from the luminophore.

[0100] <Examples of fluorescent materials with protecting groups and their molecular structures> Here, the structure of N,N'-[(2-tert-butylanthracene)-9,10-diyl]-N,N'-bis(3,5-di-tert-butylphenyl)amine (abbreviation: 2tBu-mmtBuDPhA2Anth), which is a fluorescent material that can be used in a light-emitting device of one embodiment of the present invention and is represented by the following structural formula (102), is shown. In 2tBu-mmtBuDPhA2Anth, the anthracene ring is the luminophore, and the tertiary butyl (tBu) group acts as a protecting group.

[0101] [ka]

[0102] The ball-and-stick model representation of the above 2tBu-mmtBuDPhA2Anth is shown in FIG. 4B. FIG. 4B shows the appearance of 2tBu-mmtBuDPhA2Anth when viewed from the direction of the arrow in FIG. 4A (horizontal to the anthracene ring plane). The shaded portion in FIG. 4B represents the portion directly above the anthracene ring plane, which is the luminophore, and it can be seen that the portion directly above has an area where the tBu group, which is the protecting group, overlaps. For example, in FIG. 4B, the atom indicated by the arrow (a) is the carbon atom of the tBu group that overlaps with the shaded portion, and the atom indicated by the arrow (b) is the hydrogen atom of the tBu group that overlaps with the shaded portion. That is, in 2tBu-mmtBuDPhA2Anth, the atoms constituting the protecting group are located directly above one of the luminophore planes, and the atoms constituting the protecting group are also located directly above the other plane. With this structure, even when the guest material is dispersed in the host material, the distance between the anthracene ring, which is the luminophore, and the host material can be increased in both the planar direction and the perpendicular direction of the anthracene ring, thereby suppressing energy transfer due to the Dexter mechanism.

[0103] In addition, in the case of energy transfer by the Dexter mechanism, for example, when the transition involved in the energy transfer is a transition between HOMO and LUMO, the overlap of the HOMO of the host material and the guest material and the overlap of the LUMO of the host material and the guest material are important. When the HOMO and LUMO of both materials overlap, the Dexter mechanism occurs significantly. Therefore, in order to suppress the Dexter mechanism, it is important to suppress the overlap of the HOMO and LUMO of both materials. In other words, it is important to increase the distance between the skeleton involved in the excited state and the host material. Here, in fluorescent materials, both the HOMO and LUMO are often possessed by the luminophore. For example, when the HOMO and LUMO of the guest material extend above and below the surface of the luminophore (in 2tBu-mmtBuDPhA2Anth, above and below the anthracene ring), it is important in the molecular structure to cover the above and below the surface of the luminophore with a protective group. Note that the above and below of the anthracene ring are expressed as above and below with the anthracene ring surface as the reference surface as viewed from the arrow in FIG. 4A.

[0104] In addition, the fused aromatic ring or fused heteroaromatic ring that functions as a luminophore, such as a pyrene ring or an anthracene ring, has a transition dipole vector on the ring plane. Therefore, in FIG. 4B, it is preferable that 2tBu-mmtBuDPhA2Anth has a region where the tBu group, which is a protecting group, overlaps with the plane where the transition dipole vector exists, i.e., directly on the plane of the anthracene ring. Specifically, at least one of the atoms constituting the multiple protecting groups (tBu group in FIG. 4) is located directly on one face of the fused aromatic ring or fused heteroaromatic ring (anthracene ring in FIG. 4), 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. By adopting this configuration, even if the guest material is dispersed in the host material, the distance between the luminophore and the host material can be increased, and energy transfer by the Dexter mechanism can be suppressed. In addition, it is preferable that a protecting group such as a tBu group is arranged so as to cover the luminophore such as an anthracene ring.

[0105] <Configuration Example 2 of Light-Emitting Layer 130> 5C shows an example of the correlation of energy levels in the light-emitting layer 130 of the light-emitting device 150 and the light-emitting device 152 according to one embodiment of the present invention. The light-emitting layer 130 shown in FIG. 5A includes a compound 131, a compound 132, and further a compound 133. In one embodiment of the present invention, the compound 132 is preferably a fluorescent material. In this configuration example, the compound 131 and the compound 133 form an exciplex.

[0106] The combination of compound 131 and compound 133 may be any combination capable of forming an exciplex, but it is more preferable that one of them is a compound having a function of transporting holes (hole transporting property) and the other is a compound having a function of transporting electrons (electron transporting property). In this case, it becomes easier to form a donor-acceptor type exciplex, and the exciplex can be efficiently formed. In addition, when the combination of compound 131 and compound 133 is a combination of a compound having hole transporting property and a compound having electron transporting property, it becomes possible to easily control the carrier balance by the mixing ratio. Specifically, the range of the compound having hole transporting property: the compound having electron transporting property is preferably 1:9 to 9:1 (weight ratio). In addition, since the carrier balance can be easily controlled by having this configuration, the carrier recombination region can also be easily controlled.

[0107] In addition, as a combination of host materials that efficiently form an exciplex, it is preferable 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.

[0108] The LUMO and HOMO levels of a compound can be derived from the electrochemical properties (reduction potential and oxidation potential) of the compound measured by cyclic voltammetry (CV) measurement.

[0109] For example, when compound 133 has a hole transporting property and compound 131 has an electron transporting property, as shown in the energy band diagram of Fig. 5B, the HOMO level of compound 133 is preferably higher than the HOMO level of compound 131, and the LUMO level of compound 133 is preferably higher than the LUMO level of compound 131. By making the energy levels correlated in this way, holes and electrons, which are carriers injected from a pair of electrodes (electrodes 101 and 102), are easily injected into compound 131 and compound 133, respectively, which is preferable.

[0110] In FIG. 5B, Comp(131) represents compound 131, Comp(133) represents compound 133, and ΔE C1 represents the energy difference between the LUMO and HOMO levels of compound 131, and ΔE C3 represents the energy difference between the LUMO and HOMO levels of compound 133, and ΔE E is a notation and symbol representing the energy difference between the LUMO level of compound 131 and the HOMO level of compound 133.

[0111] When Compound 131 and Compound 133 form an exciplex, a hole is injected into the HOMO of Compound 131, and an electron is injected into the LUMO of 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 ) is smaller. Therefore, by forming an exciplex with compound 131 and compound 133, it is possible to form an excited state with lower excitation energy. In addition, since the exciplex has lower excitation energy, it is possible for the exciplex to form a stable excited state.

[0112] 5C 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. 5C 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 the exciplex

[0113] 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 5C).

[0114] Excitation energy levels of exciplexes (S E and T E ) is the S1 level (S C1 and S C3 ) is lower than that of the light-emitting device of one embodiment of the present invention, an excited state can be formed with lower excitation energy. This allows the driving voltage of the light-emitting device of one embodiment of the present invention to be reduced.

[0115] The S1 level of the exciplex (S E ) and T1 level (T E) are adjacent to each other 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. 5C, Route A7). The singlet excitation energy of the exciplex can be rapidly transferred to compound 132 (Fig. 5C, Route A8). At this time, S E ≧S G In route A8, the exciplex functions as an energy donor, and compound 132 functions as an energy acceptor. Specifically, a tangent line is drawn at the base of the fluorescence spectrum of the exciplex on the short wavelength side, and the energy of the wavelength of the extrapolated line is S E The energy of the wavelength of the absorption edge of the absorption spectrum of compound 132 is S G When this is done, S E ≧S G It is preferable that:

[0116] In order to enhance the TADF property, the T1 levels of both compound 131 and compound 133, i.e., T C1 and T C3 But, T E As an index of this, it is preferable that the shortest emission peak wavelengths of the phosphorescence spectra of Compound 131 and Compound 133 are both equal to or less than the maximum emission peak wavelength of the exciplex. Alternatively, a tangent line is drawn at the base of the fluorescence spectrum of the exciplex on the short wavelength side, and the energy of the wavelength of the extrapolated line is S E Then, tangents are drawn at the short wavelength tails of the phosphorescence spectra of compounds 131 and 133, respectively, and the wavelength energy of these extrapolated lines is the T C1 and T C3 When this is done, T C1 -S E ≦0.2 eV and T C3 -S E It is preferred that it is ≦0.2 eV.

[0117] 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, whereby the guest material can emit light. Therefore, by using a combination of materials that form an exciplex in the light-emitting layer 130, the luminous efficiency of the fluorescent light-emitting device can be improved.

[0118] Here, 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, as described above, it is possible to suppress the energy transfer by the Dexter mechanism represented by route A9 and to suppress the deactivation of triplet excitation energy. Therefore, it is possible to obtain a fluorescent light-emitting device with high luminous efficiency.

[0119] The above-described processes of routes A6 to A8 may be referred to as ExSET (Exciplex-Singlet Energy Transfer) or ExEF (Exciplex-Enhanced Fluorescence) in this specification etc. In other words, in the light-emitting layer 130, excitation energy is provided from the exciplex to the fluorescent material.

[0120] <Configuration Example 3 of Light-Emitting Layer 130> In this configuration example, a case where a phosphorescent material is used as the compound 133 of the light-emitting device using the above-mentioned ExEF will be described. That is, a case where a phosphorescent material is used as one of the compounds forming an exciplex will be described.

[0121] In this configuration example, a compound having a heavy atom is used as one of the compounds forming the exciplex. Therefore, intersystem crossing between the singlet state and the triplet state is promoted. This makes it possible to form an exciplex that can transition from the triplet excited state to the singlet ground state (i.e., can exhibit phosphorescence). In this case, unlike ordinary exciplexes, the triplet excited energy level (T E ) is the energy donor level, so T E The singlet excited energy level (SG ) or more. Specifically, a tangent line is drawn at the base on the short wavelength side of the emission spectrum of an exciplex using a compound having a heavy atom as one of the compounds, and the energy of the wavelength of the extrapolated line is T E The energy of the wavelength of the absorption edge of the absorption spectrum of compound 132 is S G When this is done, T E ≧S G It is preferable that:

[0122] By using this correlation between the energy levels, the triplet excitation energy of the generated exciplex is expressed as the triplet excitation energy level (T E ) to the singlet excited energy level (S G ) energy can be transferred to the S1 level (S E ) and T1 level (T E ) are adjacent energy levels, it may be 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.

[0123] In addition, the phosphorescent material used in the above configuration preferably contains heavy atoms such as Ir, Pt, Os, Ru, and Pd. On the other hand, in this configuration example, since the phosphorescent material acts as an energy donor, the quantum yield may be high or low. In other words, it is sufficient that the energy transfer from the triplet excitation energy level of the exciplex to the singlet excitation energy level of the guest material is an allowed transition. The energy transfer from the exciplex or phosphorescent material composed of the above-mentioned phosphorescent material to the guest material is preferable because the energy transfer from the triplet excitation energy level of the energy donor to the singlet excitation energy level of the guest material (energy acceptor) is an allowed transition. Therefore, the triplet excitation energy of the exciplex is raised to the S1 level (S GThat is, triplet and singlet excitation energy can be transferred to the S1 level of the guest material only through the processes of Route A6 and Route A8. In Route A8, the exciplex functions as the energy donor, and compound 132 functions as the energy acceptor.

[0124] 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, as described above, it is possible to suppress the energy transfer due to the Dexter mechanism represented by route A9 and to suppress the deactivation of triplet excitation energy. Therefore, a fluorescent light-emitting device with high luminous efficiency can be obtained.

[0125] <Configuration Example 4 of Light-Emitting Layer 130> In this configuration example, a case where a material having TADF properties is used as compound 133 of the light-emitting device using the above-mentioned ExEF will be described with reference to FIG. 5D.

[0126] Since compound 133 is a TADF material, compound 133 that does not form an exciplex has the function of converting triplet excitation energy into singlet excitation energy by upconversion (Figure 5D Route A 10 The singlet excitation energy of compound 133 can be rapidly transferred to compound 132 (Figure 5D Route A 11 ). At this time, S C3 ≧S G It is preferable that:

[0127] As in the above-described example of the structure of the light-emitting layer, in the light-emitting device of one embodiment of the present invention, triplet excitation energy is transferred to the compound 132 as the guest material via Routes A6 to A8 in FIG. 5D, and the triplet excitation energy is transferred to the compound 132 as the guest material via Routes A7 to A8 in FIG. 10 and Route A 11There is a route where the triplet excitation energy is transferred to compound 132 via the exciplex. The existence of multiple routes for the triplet excitation energy to be transferred to the fluorescent material can further increase the luminous efficiency. In route A8, the exciplex functions as the energy donor, and compound 132 functions as the energy acceptor. 11 In the formula, compound 133 functions as an energy donor and compound 132 functions as an energy acceptor.

[0128] In this configuration example, the exciplex and compound 133 function as energy donors, and compound 132 functions as an energy acceptor.

[0129] <Configuration Example 5 of Light-Emitting Layer 130> FIG. 6A shows a case where four kinds of materials are used in the light-emitting layer 130. In FIG. 6A, the light-emitting layer 130 includes a compound 131, a compound 132, a compound 133, and a compound 134. In one embodiment of the present invention, the compound 133 has a function of converting triplet excitation energy into light emission. In this configuration example, a case where the compound 133 is a phosphorescent compound will be described. The compound 132 is a guest material that exhibits fluorescent emission. The compound 131 is an organic compound that forms an exciplex with the compound 134.

[0130] FIG. 6B shows the correlation between the energy levels of compound 131, compound 132, compound 133, and compound 134 in the light-emitting layer 130. The notations and symbols in FIG. 6B are as follows, and the other notations and symbols are the same as those in FIG. 5C. ·S C4 : S1 level of compound 134 T C4 :T1 level of compound 134

[0131] In the light-emitting device according to one embodiment of the present invention shown in this configuration example, the compound 131 and the compound 134 contained in the light-emitting layer 130 form an exciplex. E ) and the T1 level of the exciplex (T E ) are adjacent energy levels (Figure 6B Route A12 reference).

[0132] As mentioned above, the exciplex produced by the above process loses its excitation energy, and the two substances that formed the exciplex return to behaving as separate substances.

[0133] 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 light-emitting device 150 and light-emitting device 152 to be reduced.

[0134] Here, when compound 133 is a phosphorescent material, 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 In addition, the triplet excitation energy of compound 133 can be efficiently converted into the singlet excitation energy of compound 132 (Route A 14 ) where, as shown in Figure 6B, T E ≧T C3 ≧S G is preferable because the excitation energy of compound 133 is efficiently transferred as singlet excitation energy to the guest material, compound 132. Specifically, a tangent line is drawn at the base of the phosphorescence spectrum of compound 133 on the short wavelength side, and the energy of the wavelength of the extrapolated line is T C3 The energy of the wavelength of the absorption edge of the absorption spectrum of compound 132 is S G When this is done, T C3 ≧S G It is preferable that the formula is: 14 In the formula, compound 133 functions as an energy donor and compound 132 functions as an energy acceptor.

[0135] 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 transport property and the other is a compound having an electron transport property.

[0136] 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.

[0137] In addition, the correlation between the energy levels of compound 131 and compound 134 is not limited to FIG. 6B. That is, the singlet excitation energy level (S C1 ) is the singlet excited energy level of compound 134 (S C4 ) or lower. The triplet excited energy level (T C1 ) is the triplet excited energy level (T C4 ) may be higher or lower.

[0138] 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 is suitable for forming an exciplex.

[0139] 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 is suitable for forming an exciplex.

[0140] 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 the compound 132. By using this structure, as described above, Route A 15The energy transfer by the Dexter mechanism represented by the formula (I) can be suppressed, and the deactivation of triplet excitation energy can be suppressed. Therefore, a fluorescent light-emitting device with high luminous efficiency can be obtained. In addition, the concentration of the energy donor compound 133 can be increased. As a result, it is possible to achieve the inherently contradictory phenomenon of suppressing the energy transfer by the Dexter mechanism while increasing the energy transfer rate by the Förster mechanism. By increasing the energy transfer rate by the Förster mechanism, the excitation life of the energy acceptor in the light-emitting layer is shortened, and the reliability of the light-emitting device can be improved. When the energy donor compound 133 is added to the light-emitting layer, its concentration is preferably 2 wt% or more and 50 wt% or less, more preferably 5 wt% or more and 30 wt% or less, and even more preferably 5 wt% or more and 20 wt% or less, relative to the host material. With this configuration, the energy transfer rate by the Förster mechanism can be increased, and therefore a light-emitting device with high luminous efficiency can be obtained.

[0141] In addition, Route A shown above 12 and A 13 This process may be referred to as ExTET (Exciplex-Triplet Energy Transfer) in this specification and the like. In other words, in the light-emitting layer 130, excitation energy is provided from the exciplex to the compound 133. Therefore, this configuration example can be said to be a configuration in which a fluorescent material having a protecting group is mixed into a light-emitting layer that can utilize ExTET.

[0142] <Configuration Example 6 of Light-Emitting Layer 130> In this configuration example, a case will be described in which a material having TADF properties is used for the compound 134 described in the above-mentioned configuration example 5 of the light-emitting layer.

[0143] FIG. 6C shows a case where four kinds of materials are used in the light-emitting layer 130. In FIG. 6C, the light-emitting layer 130 contains a compound 131, a compound 132, a compound 133, and a compound 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 guest material that exhibits fluorescent emission. The compound 131 is an organic compound that forms an exciplex with the compound 134.

[0144] Here, since compound 134 is a TADF material, compound 134 that does not form an exciplex has the function of converting triplet excitation energy into singlet excitation energy by upconversion ( FIG. 6C Route A 16 The singlet excitation energy of compound 134 can be rapidly transferred to compound 132 (Figure 6C Route A 17 ). At this time, S C4 ≧S G Specifically, a tangent line is drawn at the short wavelength side of the fluorescence spectrum of compound 134, and the energy of the wavelength of the extrapolated line is S C4 The energy of the wavelength of the absorption edge of the absorption spectrum of compound 132 is S G When this is done, S C4 ≧S G It is preferable that:

[0145] As in the previous example of the configuration of the light-emitting layer, in the light-emitting device according to one embodiment of the present invention, route A in FIG. 12 Route A 14 The triplet excitation energy is transferred to the guest material, compound 132, via route A in FIG. 6C. 16 and Route A 17 There is a route through which triplet excitation energy is transferred to compound 132 via route A. The existence of multiple routes through which triplet excitation energy is transferred to a fluorescent material can further increase the luminescence efficiency. 14 In the above, compound 133 functions as an energy donor and compound 132 functions as an energy acceptor. 17 In the formula, compound 134 functions as an energy donor and compound 132 functions as an energy acceptor.

[0146] <Configuration Example 7 of Light-Emitting Layer 130> FIG. 7B shows an example of the correlation of energy levels in the light-emitting layer 130 of the light-emitting device 150 and the light-emitting device 152 according to one embodiment of the present invention. The light-emitting layer 130 shown in FIG. 7A contains a compound 131, a compound 132, and further a compound 133. In one embodiment of the present invention, the compound 132 is a fluorescent material having a protecting group. The compound 133 has a function of converting triplet excitation energy into light emission. In this configuration example, a case where the compound 133 is a phosphorescent material will be described.

[0147] The notations and symbols in FIG. 7B and FIG. 7C described later 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

[0148] 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. Since the compound 133 is a phosphorescent material, T C3 ≦T C1 By selecting materials with the above relationship, both the singlet and triplet excitation energies generated in compound 131 can be converted to the T C3 (Figure 7B Route A 18 ) Note that some of the carriers can be recombined with compound 133.

[0149] It is preferable that the phosphorescent material used in the above configuration contains a heavy atom such as Ir, Pt, Os, Ru, or Pd. Meanwhile, as described above, in this configuration example, the phosphorescent material acts as an energy donor, so the quantum yield may be high or low. When a phosphorescent material is used as compound 133, it is preferable that the energy transfer from the triplet excitation energy level of the energy donor to the singlet excitation energy level of the guest material (energy acceptor) is an allowed transition. Therefore, the triplet excitation energy of compound 133 is converted into a fluorine-containing compound by route A. 19 The S1 level (S G ) can be moved to Root A. 19 In this case, compound 133 functions as an energy donor and compound 132 functions as an energy acceptor. C3 ≧S G is preferable because the excitation energy of compound 133 is efficiently transferred to the singlet excited state of compound 132, which is the guest material. Specifically, a tangent line is drawn at the base of the phosphorescence spectrum of compound 133 on the short wavelength side, and the energy of the wavelength of the extrapolated line is T C3 The energy of the wavelength of the absorption edge of the absorption spectrum of compound 132 is S G When this is done, T C3 ≧S G It is preferable that:

[0150] 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 the compound 132. By using this structure, as described above, Route A 20 Thus, it is possible to suppress the deactivation of triplet excitation energy by suppressing the energy transfer due to the Dexter mechanism represented by the formula (1), thereby making it possible to obtain a fluorescent light-emitting device with high luminous efficiency.

[0151] <Configuration Example 8 of Light-Emitting Layer 130> FIG. 7C shows an example of the correlation between the energy levels in a light-emitting device 150 and a light-emitting layer 130 of the light-emitting device according to one embodiment of the present invention. The light-emitting layer 130 shown in FIG. 7A contains a compound 131, a compound 132, and further a compound 133. In one embodiment of the present invention, the compound 132 is a fluorescent material having a protecting group. The compound 133 has a function of converting triplet excitation energy into light emission. In this configuration example, a case where the compound 133 is a compound having TADF properties will be described.

[0152] The notations and symbols in FIG. 7C are as follows, and the other notations and symbols are the same as those shown in FIG. 7B. ·S C3 : S1 level of compound 133

[0153] 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 And T C3 ≦T C1 By selecting materials with the above relationship, both the singlet excitation energy and the triplet excitation energy generated in compound 131 can be converted to the S C3 and T C3 (Figure 7C Route A 21 ) Note that some of the carriers can be recombined with compound 133.

[0154] Here, since compound 133 is a TADF material, it has the function of converting triplet excitation energy into singlet excitation energy by upconversion (Figure 7C Route A 22 ). In addition, the singlet excitation energy of compound 133 can be rapidly transferred to compound 132. (Figure 7C Route A 23 ). At this time, S C3 ≧S G Specifically, a tangent line is drawn at the short wavelength side of the fluorescence spectrum of compound 133, and the energy of the wavelength of the extrapolated line is S C3The energy of the wavelength of the absorption edge of the absorption spectrum of compound 132 is S G When this is done, S C3 ≧S G It is preferable that the formula is: 21 Route A 23 Through this process, the triplet excitation energy in the light-emitting layer 130 can be converted into the fluorescent light of the compound 132. 23 In the above, compound 133 functions as an energy donor and compound 132 functions as an energy acceptor.

[0155] 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 the compound 132. By using this structure, as described above, Route A 24 Thus, it is possible to suppress the deactivation of triplet excitation energy by suppressing the energy transfer due to the Dexter mechanism represented by the formula (1), thereby making it possible to obtain a fluorescent light-emitting device with high luminous efficiency.

[0156] Next, an example of the configuration of the light-emitting layer 170 will be described.

[0157] <Configuration Example 1 of Light-Emitting Layer 170> In this configuration example, the case where the light-emitting layer 170 is a fluorescent light-emitting layer will be described.

[0158] 8B shows an example of the correlation of energy levels in the light-emitting layer 170 of the light-emitting device 150 and the light-emitting device 152 according to one embodiment of the present invention. The light-emitting layer 170 shown in FIG 8A includes at least the compound 135 and the compound 136. The compound 136 has a function of converting singlet excitation energy into light emission.

[0159] The notations and symbols in FIG. 8B are as follows: ·Host(135): Compound 135 Guest (136): Compound 136 (fluorescent material) ·S FH : S1 level of compound 135 T FH :T1 level of compound 135 ·S FG : S1 level of compound 136 (fluorescent material) T FG : T1 level of compound 136 (fluorescent material)

[0160] In the light-emitting layer 170, singlet excitons and triplet excitons are generated mainly by carrier recombination in the compound 135. It is preferable that the compound 135 has a function of converting triplet excitation energy into singlet excitation energy by TTA. With this configuration, a part of the triplet excitation energy that does not originally contribute to fluorescent emission can be converted into singlet excitation energy in the compound 135 and transferred to the compound 136 (see route E1 in FIG. 8B), and can be extracted as fluorescent emission. Therefore, the luminous efficiency of the fluorescent device can be improved. Note that the fluorescent emission by TTA is emission via a triplet excitation state with a long life, and thus delayed fluorescence is observed.

[0161] In order to efficiently transfer the singlet excitation energy to compound 136 in the light-emitting layer 170, as shown in FIG. 8B, the S1 level of compound 135 is preferably higher than the S1 level of compound 136. In addition, the T1 level of compound 135 is preferably lower than the T1 level of compound 136. With this configuration, the triplet excitation energy generated in compound 135 can be confined in compound 135, and the triplet excitation energy of compound 136 can also be transferred to compound 135 (see route E2 in FIG. 8B), so that TTA can be efficiently generated in the light-emitting layer 170.

[0162] In order to utilize TTA efficiently, it is preferable to use an organic compound having an anthracene skeleton as compound 135. Organic compounds having such skeletons tend to have low T1 levels and are suitable for light-emitting devices using TTA.

[0163] Furthermore, the T1 level of the compound 135 is preferably lower than the T1 level of the material used in the hole transport layer 117 or the electron transport layer 118 in contact with the light-emitting layer 170. In other words, it is preferable that the hole transport layer 117 or the electron transport layer 118 has a function of suppressing exciton diffusion. With this configuration, it is possible to suppress the diffusion of triplet excitons generated in the light-emitting layer 170 to the hole transport layer 117 or the electron transport layer 118, and therefore it is possible to provide a light-emitting device with good luminous efficiency.

[0164] <Configuration Example 2 of Light-Emitting Layer 170> In this configuration example, a case will be described in which the light-emitting layer 170 contains a material having a function of converting triplet excitation energy into light emission.

[0165] The light-emitting layer 170 shown in FIG. 9A contains at least a compound 135 and a compound 136. The compound 136 has a function of converting triplet excitation energy into light emission. In one embodiment of the present invention, the compound 136 is preferably a phosphorescent material. Note that in FIG. 9A, FIG. 9B, and FIG. 9C, the present configuration example shows a case where the compound 136 is a phosphorescent material.

[0166] The notations and symbols in FIGS. 9B and 9C are as follows. ·Host(135): Compound 135 ·Guest(136): Compound 136 ·S PH1 : S1 level of compound 135 T PH1 :T1 level of compound 135 T PG :T1 level of compound 136 ·S PG : S1 level of compound 136

[0167] 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 135 contained in the light-emitting layer 170. Since the compound 136 is a phosphorescent material, T PG ≦T PH1By selecting materials with the above relationship, both the singlet and triplet excitation energies generated in compound 135 can be converted to the T PG 1 level (Route E3 in FIG. 9B and FIG. 9C). Note that some of the carriers can recombine with compound 136.

[0168] In order for compound 136 to emit light efficiently, it is preferable that the longest wavelength absorption band in the absorption spectrum of compound 136 overlaps with the emission spectrum of compound 135. The longest wavelength absorption band of a phosphorescent material is the absorption band that most strongly contributes to emission among the absorption bands included in the entire absorption spectrum. In addition, the emission spectrum exhibited by compound 135 includes a fluorescence spectrum, which is emission derived from the singlet excited state of the compound, and a phosphorescence spectrum derived from the triplet excited state. Therefore, in order for compound 136 to emit light efficiently, it is preferable that both the fluorescence spectrum and phosphorescence spectrum exhibited by compound 135 overlap sufficiently with the longest wavelength absorption band of compound 136. By having the overlap, the excitation energy of compound 135 is converted into the excitation energy of compound 136. With this configuration, both the singlet excitation energy and triplet excitation energy generated in the light-emitting layer 170 can be efficiently converted into the emission of compound 136.

[0169] In order to make the fluorescence spectrum and phosphorescence spectrum of compound 135 overlap with the longest wavelength absorption band of compound 136, the difference between the energy value of the fluorescence spectrum peak of compound 135 and the peak value of the absorption band of the longest wavelength (lowest energy side) of the absorption spectrum is preferably 0.2 eV or less. More preferably, it is 0.1 eV or less. By adopting this configuration, it is possible to obtain a light-emitting layer with high luminous efficiency. Note that the magnitude relationship between the energy value of the peak of the fluorescence spectrum and the peak value of the absorption band of the longest wavelength (lowest energy side) of the absorption spectrum does not matter. In other words, the energy value of the peak of the fluorescence spectrum may be larger or smaller than the peak value of the absorption band of the longest wavelength (lowest energy side) of the absorption spectrum.

[0170] As shown in FIG. 9C, it is more preferable to use a material having a small energy difference between the S1 level and the T1 level as the compound 135. By adopting this structure, it is possible to reduce the driving voltage of the light-emitting device while having high light-emitting efficiency. Examples of materials having a small energy difference between the S1 level and the T1 level include TADF materials and exciplexes.

[0171] <Configuration Example 3 of Light-Emitting Layer 170> 10B and 10C show an example of the correlation of energy levels in the light-emitting layer 170 of the light-emitting device 150 and the light-emitting device 152 according to one embodiment of the present invention. The light-emitting layer 170 shown in FIG. 10A includes at least compounds 135_1, 135_2, and 136. The compound 136 has a function of converting triplet excitation energy into light emission. In one embodiment of the present invention, the compound 136 is preferably a phosphorescent material. Note that in this configuration example, the compound 136 is a phosphorescent material in FIGS. 10A, 10B, and 10C. The compounds 135_1 and 135_2 are combined to form an exciplex.

[0172] As with the compounds 131 and 133 in Figures 5A and 5B, the combination of the compounds 135_1 and 135_2 may be any combination capable of forming an exciplex, but it is more preferable that one of the compounds is a compound having a function of transporting holes (hole transporting property) and the other is a compound having a function of transporting electrons (electron transporting property). Figure 10B is different from Figure 5B in terms of the symbols of the compounds, but the other structures are the same, and the structures of the compounds 135_1 and 135_2 are the same as those of the compounds 131 and 133 in Figure 5B. Therefore, a detailed description of Figure 10B is omitted.

[0173] In FIG. 10B, Comp(135_1) represents compound 135_1, Comp(135_2) represents compound 135_2, and ΔE PH2 represents the energy difference between the LUMO level and the HOMO level of compound 135_1, and ΔE PH3 represents the energy difference between the LUMO level and the HOMO level of compound 135_2, and ΔEPH1 is a notation and symbol representing the energy difference between the LUMO level of compound 135_1 and the HOMO level of compound 135_2.

[0174] Furthermore, the notations and symbols in FIG. 10C are as follows. ·Host(135_1): Compound 135_1 ·Host(135_2): Compound 135_2 ·Guest(136): Compound 136 ·S PH2 :S1 level of compound 135_1 T PH2 :T1 level of compound 135_1 ·S PH3 :S1 level of compound 135_2 T PH3 :T1 level of compound 135_2 T PG :T1 level of compound 136 ·S PG : S1 level of compound 136 ·S PE : S1 level of the exciplex T PE :T1 level of the exciplex

[0175] Compound 135_1 and compound 135_2 rapidly form an exciplex when one of them receives a hole and the other receives an electron (see route E4 in FIG. 10C). Alternatively, when one of them is excited, it rapidly interacts with the other to form an exciplex. The excited energy level of the exciplex (S PE or T PE ) is the S1 level (S PH2 and S PH3 ), it is possible to form the excited state of compound 135 with lower excitation energy, which allows the driving voltage of the light-emitting device to be reduced.

[0176] And the (S PE ) and (T PE) can be transferred to the T1 level of compound 136 (a phosphorescent compound) to produce light emission (see routes E5 and E6 in FIG. 10C).

[0177] In addition, the above-described processes of routes E4 to E6 may be referred to as ExTET in this specification and the like. In other words, in the light-emitting layer 170, excitation energy is provided from the exciplex to the compound 136. Therefore, in this configuration example, ExTET is applied to the light-emitting layer 170.

[0178] In order for the compound 136 to emit light efficiently, it is preferable that the longest wavelength absorption band in the absorption spectrum of the compound 136 overlaps with the emission spectrum of the exciplex. It is known that the S1 level and the T1 level of the exciplex are close to each other. Therefore, by overlapping at least one of the fluorescence spectrum or phosphorescence spectrum of the exciplex with the longest wavelength absorption band of the compound 136, both the singlet excitation energy and the triplet excitation energy generated in the light-emitting layer 170 can be efficiently converted into the emission of the compound 136.

[0179] In order to fully overlap the fluorescence spectrum or phosphorescence spectrum of the exciplex with the longest wavelength absorption band of compound 136, the difference between the peak energy value of the fluorescence spectrum of the exciplex and the peak value of the absorption band of the longest wavelength (lowest energy side) of the absorption spectrum is preferably 0.2 eV or less. More preferably, it is 0.1 eV or less. By adopting this configuration, a phosphorescent light-emitting layer with high luminous efficiency can be obtained. Note that the magnitude relationship between the peak energy value of the fluorescence spectrum and the peak value of the absorption band of the longest wavelength (lowest energy side) of the absorption spectrum does not matter. That is, the energy value of the peak of the fluorescence spectrum may be larger or smaller than the peak value of the absorption band of the longest wavelength (lowest energy side) of the absorption spectrum.

[0180] <Configuration Example 1 of the Light-Emitting Layer 130 and the Light-Emitting Layer 170> Consider a light-emitting device in which the light-emitting layer 130 uses any one of the structures shown in the above-mentioned <Structural Example 1 of Light-Emitting Layer 130> to <Structural Example 8 of Light-Emitting Layer 130>, and the light-emitting layer 170 uses the structure shown in <Structural Example 1 of Light-Emitting Layer 170>. The light-emitting layer 170 is a light-emitting layer using the above-mentioned TTA. Even if the light-emitting layer emits light of a short wavelength side in the visible light region, such as blue, it is possible to manufacture a light-emitting device with good efficiency and reliability. The fluorescent light-emitting layer used in the light-emitting layer 130 uses a material that has a function of converting triplet excitation energy into light emission as an energy acceptor. Therefore, in order to obtain light emission of a short wavelength side in the visible light region, such as blue, from the light-emitting layer 130, it is necessary to use a material with a high T1 level, and the options for materials with a high T1 level such as in the blue region may be limited. Therefore, it is preferable that the maximum peak wavelength of the emission spectrum of the guest material (energy acceptor) used in the light-emitting layer 130 is longer than the maximum peak wavelength of the emission spectrum of the guest material used in the light-emitting layer 170. In other words, it is preferable that the S1 level of the guest material used in the light-emitting layer 130 is lower than the S1 level of the guest material used in the light-emitting layer 170. With this configuration, a light-emitting device having high light-emitting efficiency and high reliability can be obtained. In addition, since there is a wide range of materials to choose from, a light-emitting device with good characteristics can be easily manufactured.

[0181] <Configuration Example 2 of the Light-Emitting Layer 130 and the Light-Emitting Layer 170> Consider a light-emitting device in which the light-emitting layer 130 is a fluorescent light-emitting layer and the light-emitting layer 170 uses either one of the configurations shown in <Configuration Example 2 of the Light-emitting Layer 170> or <Configuration Example 3 of the Light-emitting Layer 170>. In this case, if the light-emitting layer 130 is a normal fluorescent light-emitting layer, the light-emitting layer 130 may have a lower light-emitting efficiency than the light-emitting layer 170. If the light-emitting efficiencies of the light-emitting layer 130 and the light-emitting layer 170 are significantly different from each other, for example, if the light-emitting efficiency of the light-emitting layer 130 is extremely lower than the light-emitting efficiency of the light-emitting layer 170, the light obtained from the light-emitting device 150 or the light-emitting device 152 is strong in the light originating from the light-emitting layer 170 and weak in the light originating from the light-emitting layer 130. Therefore, if the light-emitting device 150 or the light-emitting device 152 is a multi-color light-emitting device, a problem may occur in color adjustment. There is a method of using two fluorescent light-emitting units for color adjustment, but this makes the manufacturing process of the light-emitting device complicated. In the light-emitting device of one embodiment of the present invention in which any one of the structures shown in <Structure Example 1 of Light-Emitting Layer 130> to <Structure Example 8 of Light-Emitting Layer 130> is used for the light-emitting layer 130, the light-emitting layer 130, which is a fluorescent light-emitting layer, can achieve light-emitting efficiency equivalent to that of a phosphorescent light-emitting layer. Therefore, a light-emitting device in which light emission from the light-emitting layer 130 and light emission from the light-emitting layer 170 are well balanced can be easily manufactured.

[0182] <Configuration Example 3 of Light-Emitting Layer 130 and Light-Emitting Layer 170> In the light-emitting device of one embodiment of the present invention, any one of the structures shown in <Structure Example 1 of the Light-Emitting Layer 130> to <Structure Example 8 of the Light-Emitting Layer 130> may be applied to the light-emitting layer 130 and the light-emitting layer 170 independently. In this case, the light-emitting layer 130 and the light-emitting layer 170 can achieve the same emission efficiency as that of a phosphorescent light-emitting layer, even though they are fluorescent light-emitting layers. Fluorescent light emission is likely to have a small half-width of the emission spectrum. Therefore, a light-emitting device with high emission efficiency and high color purity can be obtained by using the light-emitting device of one embodiment of the present invention. In addition, the color purity can be further improved by using a microcavity structure described later. In addition, by using guest materials that exhibit different emission colors for the light-emitting layer 130 and the light-emitting layer 170, a multicolor fluorescent light-emitting device that combines high-efficiency emission and high-color purity emission can be manufactured.

[0183] <Energy transfer mechanism> Here, the Förster mechanism and the Dexter mechanism are explained. Here, the energy transfer process between the molecules of the first material and the second material is explained with respect to the donation of excitation energy from the first material in an excited state to the second material in a ground state, but the same applies when either one of them is an exciplex.

[0184] <Förster mechanism> In the Förster mechanism, energy transfer does not require direct contact between molecules, but occurs through the resonance phenomenon of dipole vibrations of the first and second materials. The first material transfers energy to the second material through the resonance phenomenon of dipole vibrations, and the first material in the excited state becomes the ground state, and the second material in the ground state becomes the excited state. The rate constant k of the Förster mechanism is h*→g is shown in Equation (1).

[0185]

number

[0186] In formula (1), ν represents the frequency, and f' h (ν) represents the normalized emission spectrum of the first material (fluorescence spectrum when energy transfer from a singlet excited state is discussed, and phosphorescence spectrum when energy transfer from a triplet excited state is discussed), and ε g (ν) represents the molar absorption coefficient of the second material, N represents Avogadro's number, n represents the refractive index of the medium, R represents the intermolecular distance between the first material and the second material, τ represents the measured excited state lifetime (fluorescence lifetime or phosphorescence lifetime), c represents the speed of light, φ represents the luminescence quantum yield (fluorescence quantum yield when discussing energy transfer from a singlet excited state, and phosphorescence quantum yield when discussing energy transfer from a triplet excited state), and K 2 is a coefficient (0 to 4) that represents the orientation of the transition dipole moments of the first and second materials. Note that in the case of random orientation, K 2 =2 / 3.

[0187] <Dexter System> In the Dexter mechanism, when a first material and a second material approach a contact distance where orbitals overlap, energy transfer occurs through the exchange of electrons of the first material in an excited state with those of the second material in a ground state. The rate constant of the Dexter mechanism is k h*→g is shown in formula (2).

[0188]

number

[0189] In formula (2), h is the Planck constant, K is a constant having the dimension of energy, ν is the frequency, and f' h (ν) represents the normalized emission spectrum of the first material (fluorescence spectrum when energy transfer from a singlet excited state is considered, and phosphorescence spectrum when energy transfer from a triplet excited state is considered), and ε' g (ν) represents the normalized absorption spectrum of the second material, L represents the effective molecular radius, and R represents the intermolecular distance between the first and second materials.

[0190] Here, the energy transfer efficiency from the first material to the second material, φ ET is expressed by the formula (3). r represents the rate constant of the emission process of the first material (fluorescence when energy transfer from a singlet excited state is considered, and phosphorescence when energy transfer from a triplet excited state is considered), and k n represents the rate constant of a non-radiative process (thermal deactivation or intersystem crossing) of the second material, and τ represents the measured lifetime of the excited state of the first material.

[0191]

number

[0192] From equation (3), the energy transfer efficiency φ ET To increase the rate constant of energy transfer, k h*→g By increasing the other competing rate constants kr +k n It can be seen that it is good if (=1 / τ) becomes relatively small.

[0193] <Concept for improving energy transfer> First, consider the energy transfer by the Förster mechanism. By substituting equation (1) into equation (3), τ can be eliminated. Therefore, in the case of the Förster mechanism, the energy transfer efficiency φ ET does not depend on the lifetime τ of the excited state of the first material. Also, the energy transfer efficiency φ ET It can be said that a higher luminescence quantum yield φ is better.

[0194] In addition, it is preferable that the emission spectrum of the first material and the absorption spectrum of the second material (absorption corresponding to the transition from the singlet ground state to the singlet excited state) overlap greatly. Furthermore, it is preferable that the molar absorption coefficient of the second material is also high. This means that the emission spectrum of the first material overlaps with the absorption band appearing at the longest wavelength of the second material. Since the direct transition from the singlet ground state to the triplet excited state in the second material is prohibited, the molar absorption coefficient related to the triplet excited state in the second material is a negligible amount. For this reason, the energy transfer process from the excited state of the first material to the triplet excited state of the second material by the Förster mechanism can be ignored, and only the energy transfer process to the singlet excited state of the second material needs to be considered.

[0195] In addition, according to formula (1), the rate of energy transfer by the Förster mechanism is inversely proportional to the sixth power of the intermolecular distance R between the first material and the second material. As described above, when R is 1 nm or less, energy transfer by the Dexter mechanism predominates. Therefore, in order to increase the rate of energy transfer by the Förster mechanism while suppressing energy transfer by the Dexter mechanism, the intermolecular distance is preferably 1 nm or more and 10 nm or less. Therefore, since it is required that the above-mentioned protecting group is not too bulky, the number of carbon atoms constituting the protecting group is preferably 3 to 10.

[0196] Next, consider the energy transfer via the Dexter mechanism. According to equation (2), the rate constant k h*→g It can be seen that in order to increase the efficiency of energy transfer, it is better to have a large overlap between the emission spectrum of the first material (fluorescence spectrum when discussing energy transfer from a singlet excited state, and phosphorescence spectrum when discussing energy transfer from a triplet excited state) and the absorption spectrum of the second material (absorption corresponding to the transition from the singlet ground state to the singlet excited state). Therefore, the optimization of the energy transfer efficiency is realized by overlapping the emission spectrum of the first material with the absorption band that appears at the longest wavelength of the second material.

[0197] In addition, by substituting equation (2) into equation (3), the energy transfer efficiency in the Dexter mechanism, φ ET It can be seen that depends on τ. Since the Dexter mechanism is an energy transfer process based on electron exchange, energy transfer occurs not only from the singlet excited state of a first material to the singlet excited state of a second material, but also from the triplet excited state of a first material to the triplet excited state of a second material.

[0198] In the light-emitting device according to one embodiment of the present invention, since the second material is a fluorescent material, it is preferable that the efficiency of energy transfer to the triplet excited state of the second material is low. That is, it is preferable that the efficiency of energy transfer from the first material to the second material based on the Dexter mechanism is low, and it is preferable that the efficiency of energy transfer from the first material to the second material based on the Förster mechanism is high.

[0199] As already mentioned, the efficiency of energy transfer in the Förster mechanism does not depend on the lifetime τ of the excited state of the first material. On the other hand, the efficiency of energy transfer in the Dexter mechanism depends on the excited-state lifetime τ of the first material. In order to reduce the efficiency of energy transfer in the Dexter mechanism, it is preferable that the excited-state lifetime τ of the first material is short.

[0200] Therefore, in one embodiment of the present invention, an exciplex, a phosphorescent material, or a TADF material is used as the first material. These materials have a function of converting triplet excitation energy into light emission. Since the energy transfer efficiency of the Förster mechanism depends on the light emission quantum yield of the energy donor, the first material that can convert the energy of the triplet excited state into light emission, such as a phosphorescent compound, an exciplex, or a TADF material, can transfer the excitation energy to the second material by the Förster mechanism. On the other hand, the configuration of one embodiment of the present invention can promote reverse intersystem crossing from the triplet excited state to the singlet excited state of the first material (exciplex or TADF material) and shorten the excitation lifetime τ of the triplet excited state of the first material. In addition, the transition from the triplet excited state to the singlet ground state of the first material (phosphorescent material or exciplex using a phosphorescent material) can be promoted and the excitation lifetime τ of the triplet excited state of the first material can be shortened. As a result, the efficiency of energy transfer in the Dexter mechanism from the triplet excited state of the first material to the triplet excited state of the fluorescent material (second material) can be reduced.

[0201] In addition, in the light-emitting device according to one embodiment of the present invention, as described above, a fluorescent material having a protecting group is used as the second material. Therefore, the intermolecular distance between the first material and the second material can be increased. Therefore, in the light-emitting device according to one embodiment of the present invention, the efficiency of energy transfer by the Dexter mechanism can be reduced by using a material having a function of converting triplet excitation energy into light emission as the first material and a fluorescent material having a protecting group as the second material. As a result, non-radiative deactivation of triplet excitation energy in the light-emitting layer 130 can be suppressed, and a light-emitting device with high light-emitting efficiency can be provided.

[0202] <Material> Next, the components of the light-emitting device according to one embodiment of the present invention will be described in detail below.

[0203] <Light-emitting layer 130> Materials that can be used for the light-emitting layer 130 are described below. An energy acceptor having a function of converting triplet excitation energy into light emission, and an energy donor having a luminophore and a protecting group are used for the light-emitting layer 130 of the light-emitting device of one embodiment of the present invention. Examples of materials having a function of converting triplet excitation energy into light emission include TADF materials, exciplexes, and phosphorescent materials.

[0204] Examples of the luminophore contained in the compound 132 functioning as an energy acceptor include a phenanthrene skeleton, a stilbene skeleton, an acridone skeleton, a phenoxazine skeleton, a phenothiazine skeleton, etc. In particular, fluorescent compounds 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.

[0205] 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 chain alkyl group having 3 to 10 carbon atoms, or a trialkylsilyl group having 3 to 12 carbon atoms.

[0206] 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, and the branched chain alkyl group having 3 to 10 carbon atoms described below is particularly preferable. However, the alkyl group is not limited to these.

[0207] Examples of the cycloalkyl group 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. In addition, when the cycloalkyl group has a substituent, the substituent may be an alkyl group 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, or a hexyl group; a cycloalkyl group having 5 to 7 carbon atoms, such as a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, or a 8,9,10-trinorbornanyl group; or an aryl group having 6 to 12 carbon atoms, such as a phenyl group, a naphthyl group, or a biphenyl group.

[0208] Examples of branched alkyl groups having 3 to 10 carbon atoms include isopropyl, sec-butyl, isobutyl, tert-butyl, isopentyl, sec-pentyl, tert-pentyl, neopentyl, isohexyl, 3-methylpentyl, 2-methylpentyl, 2-ethylbutyl, 1,2-dimethylbutyl, 2,3-dimethylbutyl, etc. The branched alkyl groups are not limited to these.

[0209] 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.

[0210] In addition, the molecular structure of the energy acceptor is preferably a structure in which the luminophore and two or more diarylamino groups are bonded, and each of the aryl groups of the diarylamino groups has at least one protective group. It is even more preferable that at least two protective groups are bonded to each of the aryl groups. This is because the greater the number of protective groups, the greater the effect of suppressing energy transfer by the Dexter mechanism when the guest material is used in the light-emitting layer. In order to suppress the increase in molecular weight and maintain sublimability, the diarylamino group is preferably a diphenylamino group. In addition, the luminophore and the diarylamino group are preferably bonded to a nitrogen atom of the diarylamino group.

[0211] In addition, by bonding two or more diarylamino groups to the luminophore, it is possible to obtain a fluorescent material with high quantum yield while adjusting the emission color. In addition, it is preferable that the diarylamino groups are bonded to the luminophore at symmetric positions. With this configuration, it is possible to obtain a fluorescent material with high quantum yield.

[0212] In addition, instead of directly introducing a protecting group to the luminophore, a protecting group may be introduced via an aryl group of the diarylamino group. This structure allows the protecting group to be arranged 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. In addition, when a protecting group is not directly bonded to the luminophore, it is preferable to introduce four or more protecting groups per luminophore.

[0213] Also, as shown in Figure 3, it is preferable that at least one of the atoms constituting the multiple protective groups is located directly on one side of the luminophore, i.e., the condensed aromatic ring or the condensed heteroaromatic ring, and at least one of the atoms constituting the multiple protective groups is located directly on the other side of the condensed aromatic ring or the condensed heteroaromatic ring. Specific methods include the following. That is, the condensed aromatic ring or the condensed heteroaromatic ring, which is the luminophore, is bonded to two or more diphenylamino groups, and the phenyl groups in the two or more diphenylamino groups each independently have a protective group at the 3rd and 5th positions.

[0214] With this configuration, a configuration can be adopted in which the protecting group at the 3- or 5-position on the phenyl group is located directly above the condensed aromatic ring or condensed heteroaromatic ring, which is the luminophore, as shown in Figure 4. As a result, the upper and lower sides of the surface of the condensed aromatic ring or condensed heteroaromatic ring can be efficiently covered, and energy transfer via the Dexter mechanism can be suppressed.

[0215] As the energy acceptor material described above, an organic compound represented by the following general formula (G1) or (G2) can be suitably used.

[0216] [ka]

[0217] In the general formulae (G1) and (G2), A represents a substituted or unsubstituted fused aromatic ring having 10 to 30 carbon atoms or a substituted or unsubstituted fused heteroaromatic ring having 10 to 30 carbon atoms; Ar 1 ~Ar 6 each independently represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 13 carbon atoms; 1 ~X 12 each independently represents one of a branched alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 12 carbon atoms; R 1 ~R 10 each independently represents one of a hydrogen atom, an alkyl group having from 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having from 3 to 10 carbon atoms, and a trialkylsilyl group having from 3 to 12 carbon atoms.

[0218] Examples of the aromatic hydrocarbon group having 6 to 13 carbon atoms include a phenyl group, a biphenyl group, a naphthyl group, and a fluorenyl group. The aromatic hydrocarbon group is not limited to these. In addition, when the aromatic hydrocarbon group has a substituent, the substituent may be an alkyl group 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, or a hexyl group; a cycloalkyl group having 5 to 7 carbon atoms, such as a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, or a 8,9,10-trinorbornanyl group; or an aryl group having 6 to 12 carbon atoms, such as a phenyl group, a naphthyl group, or a biphenyl group.

[0219] In the general formula (G1), the substituted or unsubstituted fused aromatic ring having 10 to 30 carbon atoms or the substituted or unsubstituted fused heteroaromatic ring having 10 to 30 carbon atoms represents the above-mentioned luminophore, and the above-mentioned skeleton can be used. 1 ~X 12 represents a protecting group.

[0220] In addition, in general formula (G2), the protecting group is bonded to the quinacridone skeleton, which is the luminophore, via an aromatic hydrocarbon group. This structure allows the protecting group to be arranged so as to cover the luminophore, thereby suppressing energy transfer by the Dexter mechanism. It is also possible to have a protecting group that is directly bonded to the luminophore.

[0221] As the energy acceptor material, an organic compound represented by the following general formula (G3) or (G4) can be suitably used.

[0222] [ka]

[0223] In the general formulae (G3) and (G4), A represents a substituted or unsubstituted fused aromatic ring having 10 to 30 carbon atoms or a substituted or unsubstituted fused heteroaromatic ring having 10 to 30 carbon atoms; 1~X 12 R each independently represents one of a branched alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 12 carbon atoms. 1 , R 3 , R 6 and R 8 each independently represents one of a hydrogen atom, an alkyl group having from 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having from 3 to 10 carbon atoms, and a trialkylsilyl group having from 3 to 12 carbon atoms.

[0224] In addition, it is preferable that the protective group is bonded to the luminophore via a phenylene group. With this structure, the protective group can be arranged so as to cover the luminophore, and therefore energy transfer by the Dexter mechanism can be suppressed. In addition, when the luminophore and the protective group are bonded to each other via a phenylene group and two protective groups are bonded to the phenylene group, it is preferable that the two protective groups are bonded to the phenylene group at meta positions, as shown in general formulas (G3) and (G4). With this structure, the luminophore can be efficiently covered, and therefore energy transfer by the Dexter mechanism can be suppressed. An example of the organic compound represented by general formula (G3) is the above-mentioned 2tBu-mmtBuDPhA2Anth. That is, in one embodiment of the present invention, general formula (G3) is a particularly preferable example.

[0225] As the energy acceptor material, an organic compound represented by the following general formula (G5) can be suitably used.

[0226] [ka]

[0227] In general formula (G5), X 1 ~X 8each independently represents one of a branched alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 12 carbon atoms; R 11 ~R 18 each independently represents one of hydrogen, a branched alkyl group having from 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having from 3 to 10 carbon atoms, a trialkylsilyl group having from 3 to 12 carbon atoms, or a substituted or unsubstituted aryl group having from 6 to 25 carbon atoms.

[0228] Examples of the aryl group having 6 to 25 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, and a spirofluorenyl group. The aryl group having 6 to 25 carbon atoms is not limited to these. When the aryl group has a substituent, the substituent may be the above-mentioned alkyl group having 1 to 10 carbon atoms, a branched alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, or a trialkylsilyl group having 3 to 12 carbon atoms.

[0229] Anthracene compounds have high luminescence quantum yields and small luminophore areas, so that the upper and lower sides of the anthracene surface can be efficiently covered with protective groups. An example of an organic compound represented by general formula (G5) is the above-mentioned 2tBu-mmtBuDPhA2Anth.

[0230] Examples of the compounds represented by General Formulas (G1) to (G5) are shown below in structural formulas (102) to (105) and (200) to (284). Note that the compounds represented by General Formulas (G1) to (G5) are not limited to these. The compounds represented by structural formulas (102) to (105) and (200) to (284) can be suitably used as a fluorescent material for the light-emitting device of one embodiment of the present invention. Note that the fluorescent material is not limited to these.

[0231] [ka]

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[0240]

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[0253] Examples of materials that can be suitably used as the fluorescent material for the light-emitting device of one embodiment of the present invention are shown in structural formulas (100) and (101). Note that the fluorescent material is not limited to these.

[0254] [ka]

[0255] When the compound 133 functions as an energy donor, for example, a TADF material can be used. The energy difference between the S1 level and the T1 level of the compound 133 is preferably small, specifically, greater than 0 eV and equal to or less than 0.2 eV.

[0256] When the compound 133 is a TADF material, it is preferable that the compound 133 has a skeleton having hole transport properties and a skeleton having electron transport properties. Alternatively, the compound 133 preferably has a π-electron-rich skeleton or an aromatic amine skeleton and a π-electron-deficient skeleton. This makes it easier to form a donor-acceptor type excited state in the molecule. Furthermore, it is preferable that the compound 133 has a structure in which the skeleton having electron transport properties and the skeleton having hole transport properties are directly bonded so that both the donor property and the acceptor property are strong in the molecule of the compound 133. Alternatively, it is preferable that the compound 133 has a structure in which the π-electron-rich skeleton or the aromatic amine skeleton and the π-electron-deficient skeleton are directly bonded. By strengthening both the donor property and the acceptor property in the molecule, it is possible to reduce the overlap between the region in which the molecular orbital in the HOMO of the compound 133 is distributed and the region in which the molecular orbital in the LUMO is distributed, and it is possible to reduce the energy difference between the singlet excitation energy level and the triplet excitation energy level of the compound 133. It is also possible to keep the triplet excitation energy level of the compound 133 at a high energy.

[0257] When the TADF material is composed of one type of material, for example, the following material can be used.

[0258] First, there are fullerenes and their derivatives, acridine derivatives such as proflavine, eosin, etc. Also, there are metal-containing porphyrins including magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), palladium (Pd), etc. Examples of the metal-containing porphyrin include protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF2(OEP)), etioporphyrin-tin fluoride complex (SnF2(Etio I)), and octaethylporphyrin-platinum chloride complex (PtCl2OEP).

[0259] [ka]

[0260] In addition, as the thermally activated delayed fluorescent material composed of one kind of material, a heterocyclic compound having one or both of a π-electron rich skeleton and a π-electron deficient skeleton can be used. Specifically, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 2-[ 4-(10H-phenoxazin-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: PXZ-TRZ), 3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthene-9- 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 (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 ( Abbreviated name: 4PCCzBfpm), 4-[4-(9'-phenyl-3,3'-bi-9H-carbazol-9-yl)phenyl]benzofuro[3,2-d]pyrimidine (abbreviated name: 4PCCzPBfpm), 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviated name: mPCCzPTzn-02), etc. The heterocyclic compound has a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring, and therefore has high electron transport properties and hole transport properties, and is preferred. Among these, among the skeletons having a π-electron deficient heteroaromatic ring, the pyridine skeleton, the diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), and the triazine skeleton are preferred because they are stable and reliable.In particular, benzofuropyrimidine skeleton, benzothienopyrimidine skeleton, benzofuropyrazine skeleton, and benzothienopyrazine skeleton are preferred because they have high acceptor properties and good reliability. In addition, 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 they are stable and good reliability. In addition, as the furan skeleton, a dibenzofuran skeleton is preferred, and as the thiophene skeleton, a dibenzothiophene skeleton is preferred. In addition, as the pyrrole skeleton, an indole skeleton, a carbazole skeleton, a bicarbazole skeleton, and a 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole skeleton are particularly preferred. In addition, a substance in which a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring are directly bonded is particularly preferable 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 levels of the singlet excited state and the triplet excited state is small. In addition, an aromatic ring to which an electron-withdrawing group such as a cyano group is bonded may be used instead of the π-electron deficient heteroaromatic ring. In addition, an aromatic amine skeleton, a phenazine skeleton, or the like can be used as the π-electron rich skeleton. In addition, a xanthene skeleton, a thioxanthene dioxide skeleton, an oxadiazole skeleton, a triazole skeleton, an imidazole skeleton, an anthraquinone skeleton, a boron-containing skeleton such as phenylborane or boranthrene, an aromatic ring or a heteroaromatic ring having a nitrile group or a cyano group such as benzonitrile or cyanobenzene, a carbonyl skeleton such as benzophenone, a phosphine oxide skeleton, a sulfone skeleton, or the like can be used as the π-electron deficient skeleton. 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.

[0261] [ka]

[0262] When compound 133 does not have a function of converting triplet excitation energy into luminescence, the combination of compound 131 and compound 133 or compound 131 and compound 134 is preferably a combination that forms an exciplex with each other, but is not particularly limited. 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.

[0263] Examples of the compound 131 include zinc and aluminum metal complexes, as well as 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.

[0264] In addition, the following hole transporting materials and electron transporting materials can be used.

[0265] As the hole transporting material, a material having a higher hole transporting property than that of electrons can be used. -6 cm 2 It is preferable that the hole transport material is a material having 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 be a polymer compound.

[0266] 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).

[0267] Specific examples of the carbazole derivative include 3-[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA1), 3,6-bis[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA2), and 3,6-bis[N-(4-diphenylaminophenyl)-N-(1-naphthyl)amino]-9-phenylcarbazole (abbreviation: PCzTP N2), 3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2), 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1), and the like can be mentioned.

[0268] Other examples of carbazole derivatives that can be used include 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB), 9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA), and 1,4-bis[4-(N-carbazolyl)phenyl]-2,3,5,6-tetraphenylbenzene.

[0269] 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. In this way, 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.

[0270] 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).

[0271] 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.

[0272] Examples of materials with high hole transport properties include 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB or α-NPD), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4',4''-tris(carbazol-9-yl)triphenylamine (abbreviation: TCTA), 4,4',4''-tris[N-(1-naphthyl)-N-phenylamino]triphenylamine (abbreviation: 1'-TNATA), 4,4',4''-tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA), 4,4',4''-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (abbreviation: MTDATA), 4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl mBPAFLP), N-(9,9-dimethyl-9H-fluoren-2-yl)-N-{9,9-dimethyl-2-[N'-phenyl-N'-(9,9-dimethyl-9H-fluoren-2-yl)amino]-9H-fluoren-7-yl}phenylamine (DFLADFL), N-(9,9-dimethyl-2-diphenylamino-9H-fluoren-7-yl)diphenylamine (DPNF), 2-[N-(4- diphenylaminophenyl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: DPASF), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-Di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 4-phenyldiphenyl-(9-phenyl-9H-carbazol-3-yl)amine (abbreviation: PCA1BP), N,N'-bis(9-phenylcarbazol-3-yl)-N,N'-diphenylbenzene-1,3-diamine (abbreviation: PCA2B), N,N',N''-triphenyl-N,N',N''-tris(9-phenyl Carbazol-3-yl)benzene-1,3,5-triamine (abbreviation: PCA3B), N-(4-biphenyl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9-phenyl-9H-carbazol-3-amine (abbreviation: PCBiF), N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), 9,9-dimethyl N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]spiro-9,9'-bifluoren-2-amine (abbreviation: PCBASF), 2-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: PCASF), 2,7-bis[N- Aromatic amine compounds such as (4-diphenylaminophenyl)-N-phenylamino]-spiro-9,9'-bifluorene (abbreviation: DPA2SF), N-[4-(9H-carbazol-9-yl)phenyl]-N-(4-phenyl)phenylaniline (abbreviation: YGA1BP), and N,N'-bis[4-(carbazol-9-yl)phenyl]-N,N'-diphenyl-9,9-dimethylfluorene-2,7-diamine (abbreviation: YGA2F) can be used. In addition, 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 3-[4-(9-phenanthryl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPPn), 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II), 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II), 1,3,5-tri(dibenzothiophene-4-yl)-benzene (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II), Examples of compounds that can be used include amine compounds such as 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and 4-[3-(triphenylen-2-yl)phenyl]dibenzothiophene (abbreviation: 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 an electron transporting property.

[0273] As the electron transport material, a material having a higher electron transporting property than a hole transporting property of 1×10 -6 cm 2 It is preferable that the material has an electron mobility of 1000 nm or more / Vs. As a material that easily receives 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, an oxadiazole derivative, a triazole derivative, a phenanthroline derivative, a pyridine derivative, a bipyridine derivative, and a pyrimidine derivative.

[0274] For example, metal complexes having a quinoline skeleton or a benzoquinoline skeleton, such as tris(8-quinolinolato)aluminum(III) (abbreviation: Alq), tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviation: Almq3), bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq2), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (abbreviation: BAlq), and bis(8-quinolinolato)zinc(II) (abbreviation: Znq), can be used. In addition, metal complexes having oxazole or thiazole ligands, such as bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO) and bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ), can also be used. In addition to metal complexes, 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-(dibenzothiazole) 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: 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: 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 having a pyridine skeleton such as 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOs) can also be used. Polymer compounds such as poly(2,5-pyridinediyl) (abbreviation: PPy), poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)] (abbreviation: PF-Py), and poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2'-bipyridine-6,6'-diyl)] (abbreviation: PF-BPy) can also be used. The substances mentioned here are mainly 1×10, -6 cm 2 A substance having an electron mobility of 1 / Vs or more. Note that any substance other than the above may be used as long as it has a higher electron transporting property than a hole transporting property.

[0275] Compound 133 or compound 134 is preferably a material capable of forming an exciplex with compound 131. Specifically, the hole transporting material and electron transporting material shown above can be used. In this case, it is preferable to select compound 131 and compound 133 or compound 131 and compound 134, and compound 132 (fluorescent material) so that the emission peak of the exciplex formed by compound 131 and compound 133 or compound 131 and compound 134 overlaps with the longest wavelength (low energy side) absorption band of compound 132 (fluorescent material). This makes it possible to obtain a light-emitting device with dramatically improved luminous efficiency.

[0276] Also, a phosphorescent material can be used as the compound 133. Examples of the phosphorescent material include organometallic complexes or metal complexes of iridium, rhodium, or platinum. Examples of the phosphorescent material include platinum complexes and organic iridium complexes having a porphyrin ligand, and among these, for example, organic iridium complexes such as iridium orthometal complexes are preferable. Examples of the ligand to be orthometalated include 4H-triazole ligands, 1H-triazole ligands, imidazole ligands, pyridine ligands, pyrimidine ligands, pyrazine ligands, and isoquinoline ligands. In this case, the compound 133 (phosphorescent material) has an absorption band of triplet MLCT (Metal to Ligand Charge Transfer) transition. Also, it is preferable to select the compound 133 and the compound 132 (fluorescent material) so that the emission peak of the compound 133 overlaps with the longest wavelength (low energy side) absorption band of the compound 132 (fluorescent material). This allows a light-emitting device with dramatically improved luminous efficiency to be obtained. Even if compound 133 is a phosphorescent material, it may form an exciplex with compound 131. When forming an exciplex, the phosphorescent compound does not need to emit light at room temperature, and it is sufficient that the compound can emit light at room temperature when the exciplex is formed. In this case, for example, Ir(ppz)3 or the like can be used as the phosphorescent compound.

[0277] 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 iridium(III) (abbreviation: Ir(iPr5btz)3), and other 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) (abbreviation: 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), fac-tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviation: Ir(iPrpmi)3), tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: Ir(dmpimpt-Me)3), and organometallic iridium complexes with imidazole skeletons, such as 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, and an imidazole skeleton, are particularly preferred because they have high triplet excitation energy and are excellent in reliability and luminous efficiency.

[0278] 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 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 3Organometallic iridium complexes having a pyrimidine skeleton, such as (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: Ir(dppm)2(acac)), (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III) (abbreviation: Ir(mppr-Me)2(acac)), (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III) (abbreviation: Ir(mppr-iPr)2(acac)), and tris(2-phenylpyridinato-N,C 2’ ) Iridium(III) (abbreviation: Ir(ppy)3), bis(2-phenylpyridinato-N,C 2’ )iridium(III) acetylacetonate (abbreviation: Ir(ppy)2(acac)), bis(benzo[h]quinolinato)iridium(III) acetylacetonate (abbreviation: Ir(bzq)2(acac)), tris(benzo[h]quinolinato)iridium(III) (abbreviation: Ir(bzq)3), tris(2-phenylquinolinato-N,C 2’ ) Iridium(III) (abbreviation: Ir(pq)3), bis(2-phenylquinolinato-N,C 2’ Organometallic iridium complexes with pyridine skeletons such as iridium(III) acetylacetonate (abbreviation: Ir(pq)2(acac)) and bis(2,4-diphenyl-1,3-oxazolato-N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: Ir(dpo)2(acac)), bis{2-[4'-(perfluorophenyl)phenyl]pyridinato-N,C 2’}Iridium(III) acetylacetonate (abbreviation: Ir(p-PF-ph)2(acac)), bis(2-phenylbenzothiazolato-N,C 2’Examples of such complexes include organometallic iridium complexes such as iridium(III) acetylacetonate (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.

[0279] Examples of substances having a yellow or red emission peak include those having a pyrimidine skeleton, such as (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III) (abbreviation: Ir(5mdppm)2(dibm)), bis[4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: Ir(5mdppm)2(dpm)), and bis[4,6-di(naphthalen-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: Ir(d1npm)2(dpm)). and organometallic iridium complexes with pyrazine skeletons such as (acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: Ir(tppr)2(acac)), bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: Ir(tppr)2(dpm)), and (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: Ir(Fdpq)2(acac)). 2’ ) Iridium(III) (abbreviation: Ir(piq)3), bis(1-phenylisoquinolinato-N,C 2’In addition to organometallic iridium complexes having a pyridine skeleton such as iridium(III) acetylacetonate (abbreviation: Ir(piq)2(acac)), platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum(II) (abbreviation: PtOEP), and rare earth metal complexes such as tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III) (abbreviation: Eu(DBM)3(Phen)) and tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III) (abbreviation: Eu(TTA)3(Phen)). Among the above, organometallic iridium complexes having a pyrimidine skeleton are particularly preferred because they are remarkably excellent in reliability and luminous efficiency. Furthermore, an organometallic iridium complex having a pyrazine skeleton can emit red light with good chromaticity.

[0280] Materials that can be used as the energy donor include metal halide perovskites, which can be represented by any of the following general formulas (g1) to (g3).

[0281] (SA)MX3:(g1) (LA)2(SA) n-1 M n X 3n+1 :(g2) (PA)(SA) n-1 M n X3 n+1 :(g3)

[0282] In the above general formula, M represents a divalent metal ion, and X represents a halogen ion.

[0283] Specifically, divalent cations such as lead and tin are used as divalent metal ions.

[0284] As the halogen ion, specifically, anions of chlorine, bromine, iodine, fluorine, etc. are used.

[0285] Furthermore, n represents an integer of 1 to 10. When n is greater than 10 in general formula (g2) or general formula (g3), the properties become similar to those of the metal halide perovskites represented by general formula (g1).

[0286] Also, LA is R 30 -NH3 + It represents an ammonium ion represented by the formula:

[0287] General formula R 30 -NH3 + In the ammonium ion represented by R 30 is a group consisting of one of an alkyl group, an aryl group, and a heteroaryl group having 2 to 20 carbon atoms, or a combination of an alkyl group, an aryl group, or a heteroaryl group having 2 to 20 carbon atoms with an alkylene group, a vinylene group, an arylene group, and a heteroarylene group having 6 to 13 carbon atoms, in the latter case, a plurality of alkylene groups, arylene groups, and heteroarylene groups may be linked, or a plurality of groups of the same type may be used. Note that, when a plurality of the above alkylene groups, vinylene groups, arylene groups, and heteroarylene groups are linked, the total number of alkylene groups, vinylene groups, arylene groups, and heteroarylene groups is preferably 35 or less.

[0288] SA is a monovalent metal ion or R 31 -NH3 + It is expressed as R 31 represents an ammonium ion, where R is an alkyl group having 1 to 6 carbon atoms.

[0289] PA is also NH3 + -R 32 -NH3 + or NH3 + -R 33 -R 34 -R 35 -NH3 + or a part or all of a branched polyethyleneimine having an ammonium cation, the valence of said part being +2. Note that the charges in the general formula are nearly balanced.

[0290] Here, the charges of the metal halide perovskites are not strictly balanced in all parts of the material according to the above formula, but it is sufficient that the neutrality of the entire material is generally maintained. Other ions such as free ammonium ions, free halogen ions, impurity ions, etc. may exist locally in the material, and these may neutralize the charges. In addition, neutrality may not be maintained locally on the surfaces of particles and films, or at grain boundaries of crystals, and it is not necessary to maintain neutrality in all places.

[0291] For (LA) in the above formula (g2), for example, substances represented by the following general formulae (a-1) to (a-11) and (b-1) to (b-6) can be used.

[0292] [ka]

[0293] [ka]

[0294] Furthermore, (PA) in the above general formula (g3) represents a part or all of a substance represented by any one of the following general formulae (c-1), (c-2) and (d) and a branched polyethyleneimine having an ammonium cation, and has a +2 charge. These polymers may have the charges neutralized across multiple unit lattices, and may have the charges of one unit lattice neutralized by each of the charges of two different polymer molecules.

[0295] [ka]

[0296] [ka]

[0297] However, in the above general formula, R 20 represents an alkyl group having 2 to 18 carbon atoms; R 21 , R 22 and R 23 represents hydrogen or an alkyl group having 1 to 18 carbon atoms; R 24 is represented by the following structural formula and general formula (R 24 -1)~(R 24 -14). Also, R 25 and R 26 each independently represents hydrogen or an alkyl group having 1 to 6 carbon atoms. X has a combination of monomer units A and B represented by any of the pairs (d-1) to (d-6) above, and represents a structure containing u pieces of A and v pieces of B. The order of A and B is not limited. m and l each independently represent an integer of 0 to 12, and t represents an integer of 1 to 18. u represents an integer of 0 to 17, v represents an integer of 1 to 18, and u+v represents an integer of 1 to 18.

[0298] [ka]

[0299] It should be noted that these are merely examples, and the substances that can be used as (LA) and (PA) are not limited to these.

[0300] In the three-dimensional metal halide perovskites having the composition (SA)MX3 represented by the general formula (g1), a regular octahedral structure with a metal atom M at the center and halogen atoms at six vertices is arranged three-dimensionally, sharing the halogen atoms at each vertex to form a skeleton. The structural unit of the regular octahedron with halogen atoms at each vertex is called a perovskite unit. There are zero-dimensional structures in which the perovskite units exist in isolation, linear structures in which the perovskite units are connected one-dimensionally via the halogen atoms at the vertices, sheet-like structures in which the perovskite units are connected two-dimensionally, and structures in which the perovskite units are connected three-dimensionally, and there are also complex two-dimensional structures formed by stacking multiple layers of sheet-like structures in which the perovskite units are connected two-dimensionally. There are even more complex structures. The term metal halide perovskites is used as a general term for all structures having these perovskite units.

[0301] The light-emitting layer 130 may be formed of 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-transporting layer side, a substance having a hole-transporting property may be used as a host material for the first light-emitting layer, and a substance having an electron-transporting property may be used as a host material for the second light-emitting layer.

[0302] Furthermore, the light-emitting layer 130 may contain a material (compound 137) other than the compounds 131, 132, 133, and 134. In this case, in order for the compounds 131 and 133 (or 134) to efficiently form an exciplex, it is preferable that the HOMO level of one of the compounds 131 and 133 (or 134) is the highest among the materials in the light-emitting layer 130, and the LUMO level of the other is the lowest among the materials in the light-emitting layer 130. By making such a correlation of the energy levels, the reaction of the compounds 131 and 137 to form an exciplex can be suppressed.

[0303] For example, when compound 131 has hole transport properties and compound 133 (or compound 134) has electron transport properties, the HOMO level of compound 131 is preferably higher than the HOMO level of compound 133 and the HOMO level of compound 137, and the LUMO level of compound 133 is preferably lower than the LUMO level of compound 131 and the LUMO level of compound 137. In this case, the LUMO level of compound 137 may be higher or lower than the LUMO level of compound 131. Also, the HOMO level of compound 137 may be higher or lower than the HOMO level of compound 133.

[0304] The material (compound 137) that can be used for the light-emitting layer 130 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), and Metal complexes such as bis(8-quinolinolato)zinc(II) (abbreviation: Znq), bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO), and bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ); 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazole-2-yl] ]benzene (abbreviation: OXD-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 -carbazole (abbreviation: CO11) and other heterocyclic compounds, 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 of such compounds include 9,10-diphenylanthracene (abbreviation: DPAnth), N,N-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: CzA1PA), 4-(10-phenyl-9-anthryl)triphenylamine (abbreviation: DPhPA), 4-(9H-carbazol-9-yl)-4-phenylamine (abbreviation: DPAnth), and the like. '-(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, from among these and known substances, one or more substances having an energy gap larger than the energy gap of the above-mentioned Compound 131 and Compound 132 may be selected and used.

[0305] <Light-emitting layer 170> The light-emitting layer 170 includes a light-emitting material that has a function of emitting at least one of purple, blue, blue-green, green, yellow-green, yellow, orange, and red light. The light-emitting layer 170 includes, in addition to the light-emitting material, one or both of an electron-transporting material and a hole-transporting material as a host material.

[0306] As the light-emitting material, a light-emitting substance capable of converting singlet excitation energy into light emission or a light-emitting substance capable of converting triplet excitation energy into light emission can be used.

[0307] Examples of luminescent substances capable of converting singlet excitation energy into luminescence include substances that emit fluorescence (fluorescent compounds). Fluorescent compounds are not particularly limited, but are preferably anthracene derivatives, tetracene derivatives, chrysene derivatives, phenanthrene derivatives, pyrene derivatives, perylene derivatives, stilbene derivatives, acridone derivatives, coumarin derivatives, phenoxazine derivatives, and phenothiazine derivatives, and for example, the following substances can be used.

[0308] Specifically, 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine (abbreviation: PAP2BPy), 5,6-bis[4'-(10-phenyl-9-anthryl)biphenyl-4-yl]-2,2'-bipyridine (abbreviation: PAPP2BPy), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn), N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-N,N'-bis(4-tert-butylphenyl)pyrene-1,6-diamine (abbreviation: 1,6tBu-FLPAPrn), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-3,8-dicyclohexylpyrene-1,6-diamine (abbreviation: ch-1,6FLPAPrn), N,N'-(pyrene-1,6-di 1,6BnfAPrn-03), N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenylstilbene-4,4'-diamine (Abbreviation: YGA2S), 4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (Abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (Abbreviation: 2YGAPPA), N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetra(tert-butyl)perylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), N,N''-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene)bis[N,N',N'-triphenyl-1,4-phenylenediamine] (abbreviation: DPABPA), N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), N,N,N',N',N'',N'',N'''',N'''-octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), Coumarin 3 0, N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCABPhA), N-(9,10-diphenyl-2-anthryl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,N',N'- Triphenyl-1,4-phenylenediamine (abbreviation: 2DPABPhA), 9,10-bis(1,1'-biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracen-2-amine (abbreviation: 2YGABPhA), N,N,9-triphenylanthracen-9-amine (abbreviation: DPhAPhA), Coumarin 6, Coumarin 545T, N,N'-diphenylquinacridone (abbreviation: DPQd), Rubrene, 2,8-di-tert-butyl-5,11-bis(4-tert-butylphenyl)-6,12- Diphenyltetracene (abbreviation: TBRb), Nile Red, 5,12-bis(1,1'-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyran-4-ylidene)propanedinitrile (abbreviation: DCM1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM2), N,N,N',N'-Tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviation: p-mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin- 9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB), 2-(2,6-bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDCM), 2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJTM), 5,10,15,20-tetraphenylbisbenzo[5,6]indeno[1,2,3-cd:1',2',3'-lm]perylene (abbreviation: DBP), etc.

[0309] Furthermore, examples of luminescent substances capable of converting triplet excitation energy into luminescence include phosphorescent compounds.

[0310] 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 iridium(III) (abbreviation: Ir(iPr5btz)3), and other 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) (abbreviation: 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), fac-tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviation: Ir(iPrpmi)3), tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: Ir(dmpimpt-Me)3), and organometallic iridium complexes with imidazole skeletons, such as 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, and an imidazole skeleton, are particularly preferred because they have high triplet excitation energy and are excellent in reliability and luminous efficiency.

[0311] Examples of substances having a green or yellow emission peak include tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: Ir(mppm)3), tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation: Ir(tBuppm)3), (acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium(III) (abbreviation: Ir(mppm)2(acac) ... (acetylacetonato)bis[4-(2-norbornyl)-6-phenylpyrimidinato]iridium(III) (abbreviation: Ir(nbppm)2(acac)), (acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: Ir(tBuppm)2(acac)), ... Organometallic compounds with pyrimidine skeletons such as Ir(mpmppm)2(acac)), (acetylacetonato)bis{4,6-dimethyl-2-[6-(2,6-dimethylphenyl)-4-pyrimidinyl-κN3]phenyl-κC}iridium(III) (abbreviation: Ir(dmppm-dmp)2(acac)), and (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: Ir(dppm)2(acac)). Iridium complexes, organometallic iridium complexes with pyrazine skeletons such as (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinate)iridium(III) (abbreviation: Ir(mppr-Me)2(acac)) and (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinate)iridium(III) (abbreviation: Ir(mppr-iPr)2(acac)), and tris(2-phenylpyrazinate-N,C 2’ ) Iridium(III) (abbreviation: Ir(ppy)3), bis(2-phenylpyridinato-N,C 2’)iridium(III) acetylacetonate (abbreviation: Ir(ppy)2(acac)), bis(benzo[h]quinolinato)iridium(III) acetylacetonate (abbreviation: Ir(bzq)2(acac)), tris(benzo[h]quinolinato)iridium(III) (abbreviation: Ir(bzq)3), tris(2-phenylquinolinato-N,C 2’ ) Iridium(III) (abbreviation: Ir(pq)3), bis(2-phenylquinolinato-N,C 2’ Organometallic iridium complexes with pyridine skeletons such as iridium(III) acetylacetonate (abbreviation: Ir(pq)2(acac)) and bis(2,4-diphenyl-1,3-oxazolato-N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: Ir(dpo)2(acac)), bis{2-[4'-(perfluorophenyl)phenyl]pyridinato-N,C 2’}Iridium(III) acetylacetonate (abbreviation: Ir(p-PF-ph)2(acac)), bis(2-phenylbenzothiazolato-N,C 2’ Examples of such complexes include organometallic iridium complexes such as iridium(III) acetylacetonate (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.

[0312] Examples of substances having a yellow or red emission peak include those having a pyrimidine skeleton, such as (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III) (abbreviation: Ir(5mdppm)2(dibm)), bis[4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: Ir(5mdppm)2(dpm)), and bis[4,6-di(naphthalen-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: Ir(d1npm)2(dpm)). and organometallic iridium complexes with pyrazine skeletons such as (acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: Ir(tppr)2(acac)), bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: Ir(tppr)2(dpm)), and (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: Ir(Fdpq)2(acac)). 2’ ) Iridium(III) (abbreviation: Ir(piq)3), bis(1-phenylisoquinolinato-N,C 2’ In addition to organometallic iridium complexes having a pyridine skeleton such as iridium(III) acetylacetonate (abbreviation: Ir(piq)2(acac)), platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum(II) (abbreviation: PtOEP), and rare earth metal complexes such as tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III) (abbreviation: Eu(DBM)3(Phen)) and tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III) (abbreviation: Eu(TTA)3(Phen)). Among the above, organometallic iridium complexes having a pyrimidine skeleton are particularly preferred because they are remarkably excellent in reliability and luminous efficiency. Furthermore, an organometallic iridium complex having a pyrazine skeleton can emit red light with good chromaticity.

[0313] In addition to phosphorescent compounds, TADF materials can be used as materials capable of converting triplet excitation energy into light emission.

[0314] In addition, heterocyclic compounds having a π-electron rich heteroaromatic skeleton and a π-electron deficient heteroaromatic skeleton can also be used as the thermally activated delayed fluorescent compound composed of one kind of 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-xanthen-9-one (abbreviation: ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), 10-phenyl-10H,10'H-spiro[acridin-9,9'-anthracene]-10'-one (abbreviation: ACRSA), etc. The heterocyclic compound has a π-electron-rich heteroaromatic skeleton and a π-electron-deficient heteroaromatic skeleton, and therefore has high electron transport properties and hole transport properties, making it preferable. Among the π-electron-deficient heteroaromatic skeletons, diazine skeletons (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton) or triazine skeletons are preferred because they are stable and reliable. Among the π-electron-rich heteroaromatic skeletons, acridine skeleton, phenoxazine skeleton, phenothiazine skeleton, furan skeleton, thiophene skeleton, and pyrrole skeleton are stable and reliable, so it is preferred to have one or more selected from these skeletons. As the pyrrole skeleton, indole skeleton, carbazole skeleton, and 9-phenyl-3,3'-bi-9H-carbazole skeleton are particularly preferred.In addition, a substance in which a π-electron-rich heteroaromatic skeleton and a π-electron-deficient heteroaromatic skeleton are directly bonded is particularly preferable because the donor property of the π-electron-rich heteroaromatic skeleton and the acceptor property of the π-electron-deficient heteroaromatic skeleton are both strong, and the difference between the singlet excitation energy level and the triplet excitation energy level is small.

[0315] In addition, the material exhibiting thermally activated delayed fluorescence may be a material that can generate a singlet excited state from a triplet excited state by reverse intersystem crossing on its own, or may be composed of multiple materials that form an exciplex (also called an exciplex).

[0316] As the host material used in the light-emitting layer 170, a hole-transporting material and an electron-transporting material can be used.

[0317] Materials that can be used as the host material of the light-emitting layer are not particularly limited, and examples thereof include tris(8-quinolinolato)aluminum(III) (abbreviation: Alq3), 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: B Alq), bis(8-quinolinolato)zinc(II)(abbreviation: Znq), bis[2-(2-benzoxazolyl)phenolato]zinc(II)(abbreviation: ZnPBO), bis[2-(2-benzothiazolyl)phenolato]zinc(II)(abbreviation: ZnBTZ), and other metal complexes; 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), and other metal complexes; 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), 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 of such compounds include 9,10-diphenylanthracene (abbreviation: DPAnth), N,N-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: CzA1PA), 4-(10-phenyl-9-anthryl)triphenylamine (abbreviation: DPhPA), YGAPA, PCAPA, N,9-diphenyl-N-{4-[4-(10-phenyl-9-anthryl)phenyl]phenyl}-9H-carbazol-3-amine (abbreviation: PCAPBA), 2PCAPA, 6,12-dimethoxy-5,11-diphenylchrysene, DBC1, 9-[4-(10-phenyl -9-anthracenyl)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), etc. can be mentioned. Among these and various substances, one or more substances having a larger energy gap than the energy gap of the above-mentioned light-emitting material may be selected and used. In addition, when the light-emitting material is a phosphorescent compound, a substance having a larger triplet excitation energy than the triplet excitation energy of the light-emitting material may be selected as the host material.

[0318] In addition, when a plurality of materials are used as the host material of the light-emitting layer, it is preferable to use two kinds of compounds that form an exciplex in combination. In this case, various carrier transport materials can be appropriately used, but it is particularly preferable to combine an electron transport material and a hole transport material in order to efficiently form an exciplex.

[0319] As the electron transport material, metal complexes having zinc or aluminum, and π-electron-deficient heteroaromatic compounds such as nitrogen-containing heteroaromatic compounds can be used. Specifically, metal complexes such as bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq2), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (abbreviation: BAlq), bis(8-quinolinolato)zinc(II) (abbreviation: Znq), bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO), and bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ) can be used. 4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), and other heterocyclic compounds with an azole skeleton, such as 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzo 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDBTPDBq-II), 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 4,6-bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl] Heterocyclic compounds having a diazine skeleton, such as pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), and 4-{3-[3'-(9H-carbazol-9-yl)]biphenyl-3-yl}benzofuro[3,2-d]pyrimidine (abbreviation: 4mCzBPBfpm) and heterocyclic compounds having a triazine 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), 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviation: TmPPPyTz), and 2,4,6-tris(2-pyridyl)-1,3,5-triazine (abbreviation: 2Py3Tz), and heterocyclic compounds having a pyridine 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). Among the above, heterocyclic compounds having a diazine skeleton and a triazine skeleton and heterocyclic compounds having a pyridine skeleton are preferable because of their high reliability. In particular, heterocyclic compounds having a diazine (pyrimidine or pyrazine) skeleton and a triazine skeleton have high electron transport properties and contribute to reducing the driving voltage.

[0320] As the hole transport material, π-electron-rich heteroaromatic compounds (e.g., carbazole derivatives and indole derivatives) or aromatic amines can be suitably used. Specifically, 2-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: PCASF), 4,4',4''-tris[N-(1-naphthyl)-N-phenylamino]triphenylamine (abbreviation: 1-TNATA), 2,7-bis[N-(4-diphenylaminophenyl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: DPA2SF), N,N'-bis(9-phenylcarbazol-3-yl)-N,N'-diphenylbenzene- 1,3-diamine (abbreviation: PCA2B), N-(9,9-dimethyl-2-diphenylamino-9H-fluoren-7-yl)diphenylamine (abbreviation: DPNF), N,N',N''-triphenyl-N,N',N''-tris(9-phenylcarbazol-3-yl)benzene-1,3,5-triamine (abbreviation: PCA3B), 2-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: PCASF), 2-[N-(4-diphenylaminophenyl N,N'-bis[4-(carbazol-9-yl)phenyl]-N,N'-diphenyl-9,9-dimethylfluorene-2,7-diamine (abbreviation: YGA2F), 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4'-bis[N-(4 -diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), 4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), N-(9,9-dimethyl-9H-fluoren-2-yl)-N-{9,9-Dimethyl-2-[N'-phenyl-N'-(9,9-dimethyl-9H-fluoren-2-yl)amino]-9H-fluoren-7-yl}phenylamine (abbreviation: DFLADFL), 3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3-[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA1), 3,6-bis[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA1), N,N'-bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviation: DNTPD), 3,6-bis[N-(4-diphenylaminophenyl)-N-(1-naphthyl)amino]-9-phenylcarbazole (abbreviation: PCzTPN2), 3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2), 4-phenyl-4'-(9-phenyl-9H-carbazole 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)a N-(4-biphenyl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9-phenyl-9H-carbazol-3-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]spiro-9,9'-bifluoren-2-amine (abbreviation: PCBASF), N-(4-biphenyl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9-phenyl-9H-carbazol-3-amine (abbreviation: PCBiF), N-(1,Compounds with aromatic amine skeletons such as 1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), compounds with carbazole skeletons such as 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), and 9-phenyl-9H-3-(9-phenyl-9H-carbazol-3-yl)carbazole (abbreviation: PCCP), and compounds with 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzyl)carbazole (abbreviation: PCCP) Examples of the compounds include compounds having a thiophene skeleton such as 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), and 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and compounds having a furan skeleton such as 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II), and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II). Among the above, compounds having an aromatic amine skeleton and compounds having a carbazole skeleton are preferable because they have good reliability, high hole transport properties, and contribute to reducing the driving voltage.

[0321] Note that the combination of host materials that form an exciplex is not limited to the above-mentioned compounds, and any combination that can transport carriers and form an exciplex may be used as long as the emission of the exciplex overlaps with the longest wavelength absorption band in the absorption spectrum of the light-emitting material (absorption corresponding to the transition from the singlet ground state to the singlet excited state of the light-emitting material). Other materials may also be used.

[0322] Furthermore, a thermally activated delayed fluorescent material may be used as the host material for the light-emitting layer.

[0323] In addition, the electron transport material used in the light emitting layer can be the same as the electron transport material used in the electron injection layer, which simplifies the fabrication of the light emitting device and reduces the manufacturing cost of the light emitting device.

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

[0325] The electrodes 101 and 102 have a function of injecting holes and electrons into the light-emitting layer 130 and the light-emitting layer 170. The electrodes 101 and 102 can be formed using a metal, an alloy, a conductive compound, or a mixture or laminate of these. A typical example of the metal is aluminum (Al), and 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 be used as the transition metal. As the alloy, an alloy containing the above metal can be used, and examples thereof include MgAg and AlLi. Examples of the conductive compound include metal oxides such as indium tin oxide (hereinafter, 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 electrodes 101 and 102 may be formed by stacking a plurality of these materials.

[0326] Furthermore, light emitted from the light-emitting layers 130 and 170 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 -2 Examples of suitable conductive materials include a material having a resistivity of Ω·cm or less. The electrode for extracting light may be made of a conductive material having both a light transmitting function and a light reflecting function. The conductive material has a visible light reflectance of 20% to 80%, preferably 40% to 70%, and a resistivity of 1×10 -2 Examples of such materials include conductive materials with a resistivity of Ω·cm or less. When using a material with low optical transparency such as a metal or alloy 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).

[0327] In this specification and the like, the electrode having a function of transmitting light may be made of a material having a function of transmitting visible light and having electrical conductivity, and may include, for example, an oxide semiconductor layer or an organic conductor layer containing an organic substance, in addition to the oxide conductor layer typified by ITO as described above. 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, and a layer containing a composite material obtained by mixing an organic compound and an electron acceptor. 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.

[0328] The electrodes 101 and 102 can be formed by any suitable method, such as sputtering, vapor deposition, printing, coating, MBE (Molecular Beam Epitaxy), CVD, pulsed laser deposition, or ALD (Atomic Layer Deposition).

[0329] <Hole injection layer> The hole injection layer 111 has a function of promoting hole injection by reducing the hole injection barrier from one of the pair of electrodes (electrode 101 or electrode 102), and is formed of, for example, a transition metal oxide, a phthalocyanine derivative, or an aromatic amine. Examples of transition metal oxides include molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, and manganese oxide. Examples of phthalocyanine derivatives include phthalocyanine and metal phthalocyanine. Examples of aromatic amines include benzidine derivatives and phenylenediamine derivatives. Polymer compounds such as polythiophene and polyaniline can also be used, and a representative example is poly(ethylenedioxythiophene) / poly(styrenesulfonic acid), which is a self-doped polythiophene.

[0330] The hole injection layer 111 may be a layer having 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 stationary state or in 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. Specifically, 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), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviation: F6-TCNNQ) can be mentioned. In particular, a compound in which an electron-withdrawing group is bonded to a condensed aromatic ring having a plurality of heteroatoms, such as HAT-CN, is thermally stable and preferable. Radialene derivatives having an electron-withdrawing group (especially a halogen group such as a fluoro group or a cyano group) [3] are preferred because they have a very high electron-accepting property. Specific examples include α,α',α''-1,2,3-cyclopropane triylidene tris[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α',α''-1,2,3-cyclopropane triylidene tris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], and α,α',α''-1,2,3-cyclopropane triylidene tris[2,3,4,5,6-pentafluorobenzeneacetonitrile]. Transition metal oxides, for example, oxides of metals from Group 4 to Group 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.

[0331] As the hole transporting material, a material having a higher hole transporting property than that of electrons can be used.-6 cm 2 It is preferable that the material has a hole mobility of 100 / Vs or more. Specifically, aromatic amines and carbazole derivatives listed as hole transporting materials that can be used for the light emitting layer 130 can be used. In addition, aromatic hydrocarbons and stilbene derivatives can be used. The hole transporting material may be a polymer compound.

[0332] 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. In this way, 1 × 10 -6 cm 2 It is more preferable to use an aromatic hydrocarbon having a hole mobility of 1 / Vs or more and a carbon number of 14 or more and 42 or less.

[0333] 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).

[0334] 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.

[0335] <Hole transport layer> The hole transport layer 112 is a layer containing a hole transport material, and can use the materials exemplified as the material of the hole injection layer 111. The hole transport layer 112 has a function of transporting holes injected into the hole injection layer 111 to the light emitting layer 130 or the light emitting layer 170, and therefore preferably has a HOMO level that is the same as or close to the HOMO level of the hole injection layer 111.

[0336] 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 having a high hole transporting property may be a single layer or a stack of two or more layers made of the above-mentioned materials.

[0337] ≪Electron transport layer≫ The electron transport layer 118 has a function of transporting electrons injected from the other of the pair of electrodes (electrode 101 or electrode 102) through the electron injection layer 119 to the light-emitting layer 130 or the light-emitting layer 170. As the electron transport material, a material having a higher electron transporting property than a hole transporting property can be used. -6 cm 2 / Vs or more. Examples of compounds that can easily accept electrons (materials having electron transport properties) include π-electron-deficient heteroaromatic compounds such as nitrogen-containing heteroaromatic compounds and metal complexes. 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, the electron transport properties of the light-emitting layer 130 may be more preferably 1×10 -6 cm 2 It is preferable that the electron-transporting layer is a material having an electron mobility of 100 / Vs or more. Note that any material other than the above may be used as the electron-transporting layer as long as it has a higher electron-transporting property than a hole-transporting property. The electron-transporting layer 118 may be a single layer or a stack of two or more layers made of the above materials.

[0338] 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 or the light emitting layer 170. 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 it becomes possible to adjust the carrier balance by suppressing the movement of electron carriers. Such a configuration is highly effective in suppressing problems (e.g., shortening of device life) caused by electrons penetrating the light emitting layer.

[0339] ≪Electron injection layer≫ The electron injection layer 119 has a function of promoting electron injection by reducing the barrier for electron injection from the electrode 102, and may be made of, for example, a Group 1 metal, a Group 2 metal, or an oxide, halide, or carbonate thereof. A composite material of the above-mentioned electron transport material and a material that exhibits electron donating properties may also be used. Examples of materials that exhibit electron donating properties include Group 1 metals, Group 2 metals, or oxides of these metals. Specific examples include lithium fluoride (LiF), sodium fluoride (NaF), cesium fluoride (CsF), calcium fluoride (CaF2), lithium oxide (LiO x ) or an alkaline earth metal, or a compound thereof, can be used. Also, a rare earth metal compound, such as erbium fluoride (ErF3), can be used. Also, an electride can be used for the electron injection layer 119. For example, the electride can be a substance in which a high concentration of electrons is added to a mixed oxide of calcium and aluminum. Also, a substance that can be used for the electron transport layer 118 can be used for the electron injection layer 119.

[0340] In addition, a composite material obtained by mixing an organic compound and an electron donor (donor) may be used for the electron injection layer 119. Such a composite material has excellent electron injection and electron transport properties because electrons are generated in the organic compound by the electron donor. In this case, the organic compound is preferably a material that is excellent in transporting the generated electrons, and specifically, for example, the above-mentioned substances constituting the electron transport layer 118 (metal complexes, heteroaromatic compounds, etc.) can be used. As the electron donor, any substance that exhibits electron donating properties to the organic compound may be used. Specifically, alkali metals, alkaline earth metals, and rare earth metals are preferred, and examples thereof include lithium, cesium, magnesium, calcium, erbium, and ytterbium. In addition, alkali metal oxides and alkaline earth metal oxides are preferred, and examples thereof include lithium oxide, calcium oxide, and barium oxide. In addition, a Lewis base such as magnesium oxide can also be used. In addition, an organic compound such as tetrathiafulvalene (abbreviation: TTF) can also be used.

[0341] The above-mentioned light-emitting layer, hole injection layer, hole transport layer, electron transport layer, and electron injection layer can be formed by a method such as a vapor deposition method (including a vacuum vapor deposition method), an inkjet method, a coating method, a nozzle printing method, a gravure printing method, etc. In addition to the above-mentioned materials, the above-mentioned light-emitting layer, hole injection layer, hole transport layer, electron transport layer, and electron injection layer may use inorganic compounds such as quantum dots or polymeric compounds (oligomers, dendrimers, polymers, etc.).

[0342] As the quantum dots, colloidal quantum dots, alloy quantum dots, core-shell quantum dots, core quantum dots, etc. may be used. Quantum dots containing element groups of groups 2 and 16, 13 and 15, 13 and 17, 11 and 17, or 14 and 15 may 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 be used.

[0343] Examples of liquid media that can be used in the wet process include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, aromatic hydrocarbons such as toluene, xylene, mesitylene, and cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin, and dodecane, and organic solvents such as dimethylformamide (DMF) and dimethyl sulfoxide (DMSO).

[0344] Examples of polymer compounds that can be used in the light-emitting layer include polyphenylenevinylene (PPV) derivatives such as poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (abbreviation: MEH-PPV) and poly(2,5-dioctyl-1,4-phenylenevinylene), 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)] (abbreviation 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) (abbreviation P3HT), and polyphenylene derivatives. Furthermore, these polymer compounds, poly(N-vinylcarbazole) (abbreviation: PVK), poly(2-vinylnaphthalene), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (abbreviation: PTAA), etc. 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.

[0345] <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.

[0346] 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 can also be used. A flexible substrate is a bendable (flexible) substrate, and examples of such substrates include plastic substrates made of polycarbonate and polyarylate. Films, inorganic deposition films, and the like can also be used. Any other substrate may be used as long as it functions as a support in the manufacturing process of the light-emitting device and the optical element. Alternatively, any substrate may be used as long as it has a function of protecting the light-emitting device and the optical element.

[0347] 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 the substrate include a semiconductor substrate (e.g., a single crystal substrate or a silicon substrate), an SOI substrate, a glass substrate, a quartz substrate, a plastic substrate, a metal substrate, a stainless steel substrate, a substrate having stainless steel foil, a tungsten substrate, a substrate having tungsten foil, a flexible substrate, a laminated film, cellulose nanofiber (CNF) or paper containing a fibrous material, or a base film. Examples of glass substrates include barium borosilicate glass, aluminoborosilicate glass, or soda lime glass. Examples of flexible substrates, laminated films, base films, and the like include the following. For example, there are plastics typified by polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), and polytetrafluoroethylene (PTFE). Alternatively, there are resins such as acrylic resins. Alternatively, there are polypropylene, polyester, polyvinyl fluoride, or polyvinyl chloride. Alternatively, examples include polyamide, polyimide, aramid resin, epoxy resin, inorganic vapor deposition film, and paper.

[0348] 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 a part or all of the light-emitting device is completed thereon, and transfer the device to another substrate. In this case, the light-emitting device can be transferred to a substrate having poor heat resistance or a flexible substrate. The release layer may be, for example, a laminated structure of inorganic films of a tungsten film and a silicon oxide film, or a structure in which a resin film such as polyimide is formed on a substrate.

[0349] 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 above-mentioned substrates, 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, hemp), synthetic fibers (nylon, polyurethane, polyester), or regenerated fibers (acetate, cupra, rayon, regenerated polyester), etc.), a leather substrate, or a rubber substrate. By using these substrates, a light-emitting device that is not easily broken, has high heat resistance, is lightweight, or is thin.

[0350] Also, for example, a field effect transistor (FET) may be formed on the above-mentioned substrate, 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 driving of the light-emitting device is controlled by the FET.

[0351] <Microcavity structure> Furthermore, in a light-emitting device which is one embodiment of the present invention, for example, electrode 101 shown in FIGS. 1A and 1B may be formed from a conductive material having a light reflecting function, and electrode 102 may be formed from a conductive material having a light transmitting function and a light reflecting function, forming a micro-optical resonator (microcavity) structure. This allows the light emitted from light-emitting layer 130 or light-emitting layer 170 to resonate between the two electrodes, and the intensity of light having a desired wavelength among the light emitted from electrode 102 can be increased.

[0352] Although the case where light is extracted to the electrode 102 side (cathode side) will be described here, a configuration where light is extracted to the electrode 101 side (anode side) may also be used. In that case, the electrode 101 may be formed of a conductive material having a light reflecting function and a light transmitting function, and the electrode 102 may be formed of a conductive material having a light reflecting function.

[0353] The light emitted from the light emitting layer 130 and the light emitting layer 170 is resonated between a pair of electrodes (for example, the electrode 101 and the electrode 102). The light emitting layer 130 and the light emitting layer 170 are formed at positions where the intensity of light of a desired wavelength among the emitted light is increased. For example, by adjusting the optical distance from the reflection region of the electrode 101 to the light emitting region of the light emitting layer 170 and the optical distance from the reflection region of the electrode 102 to the light emitting region of the light emitting layer 170, the intensity of light of a desired wavelength among the light emitted from the light emitting layer 170 can be increased. By adjusting the optical distance from the reflection region of the electrode 101 to the light emitting region of the light emitting layer 130 and the optical distance from the reflection region of the electrode 102 to the light emitting region of the light emitting layer 130, the intensity of light of a desired wavelength among the light emitted from the light emitting layer 130 can be increased. That is, in the case of a light emitting device in which a plurality of light emitting layers (here, light emitting layer 130 and light emitting layer 170) are stacked, it is preferable to optimize the optical path of each of light emitting layer 130 and light emitting layer 170.

[0354] For example, in order to amplify light of a desired wavelength (wavelength: λ) obtained from the light-emitting layer 130, it is preferable to adjust the optical distance from the reflection region of the electrode 101 to the region (light-emitting region) in the light-emitting layer 130 where light of the desired wavelength is obtained, and the optical distance from the reflection region of the electrode 102 to the region (light-emitting region) in the light-emitting layer 130 where light of the desired wavelength is obtained, to be close to (2m'-1)λ / 4 (where m' is a natural number). Note that the light-emitting region referred to here refers to a recombination region of holes and electrons in the light-emitting layer 130.

[0355] By carrying out such optical adjustment, the emission spectrum obtained from the light-emitting layer 130 can be narrowed, and light with good color purity can be obtained.

[0356] The electrode 101, the electrode 102, the electrode 103, and the electrode 104 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).

[0357] ≪Light blocking layer≫ The light-shielding layer 223 has a function of suppressing reflection of external light. Alternatively, the light-shielding layer 223 has a function of preventing mixing of colors of light emitted from adjacent light-emitting devices. The light-shielding layer 223 may be made of a metal, a resin containing a black pigment, carbon black, a metal oxide, a composite oxide containing a solid solution of a plurality of metal oxides, or the like.

[0358] <Optical elements> The optical elements 224B, 224G, and 224R have a function of selectively transmitting light of a specific color from the incident light. For example, the light emitted from the region 222B via the optical element 224B is blue light, the light emitted from the region 222G via the optical element 224G is green light, and the light emitted from the region 222R via the optical element 224R is red light.

[0359] For example, a colored layer (also called a color filter), a bandpass filter, a multilayer filter, etc. can be applied to the optical element 224R, the optical element 224G, and the optical element 224B. Also, a color conversion element can be applied to the optical element. The color conversion element is an optical element that converts incident light into light with a longer wavelength than the wavelength of the light. It is preferable that the color conversion element is an element that uses quantum dots. By using quantum dots, the color reproducibility of the display device can be improved.

[0360] One or more other optical elements may be provided on the optical elements 224R, 224G, and 224B. Examples of other optical elements include a circular polarizer and an anti-reflection film. If a circular polarizer is provided on the side from which light emitted by a light-emitting device of the display device is extracted, it is possible to prevent the phenomenon in which light incident from the outside of the display device is reflected inside the display device and emitted to the outside. Furthermore, if an anti-reflection film is provided, it is possible to weaken the external light reflected on the surface of the display device. This allows the light emitted by the display device to be clearly observed.

[0361] ≪Bulkhead≫ The partition 145 may be formed using an inorganic or organic material as long as it has insulating properties. Examples of the inorganic material include silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, aluminum oxide, and aluminum nitride. Examples of the organic material include photosensitive resin materials such as acrylic resin and polyimide resin.

[0362] The silicon oxynitride film refers to a film having a higher oxygen content than nitrogen in its composition, preferably a film having an oxygen content of 55 atomic % to 65 atomic % inclusive, a nitrogen content of 1 atomic % to 20 atomic % inclusive, a silicon content of 25 atomic % to 35 atomic % inclusive, and a hydrogen content of 0.1 atomic % to 10 atomic % inclusive. The silicon nitride oxide film refers to a film having a higher nitrogen content than oxygen in its composition, preferably a film having an oxygen content of 55 atomic % to 65 atomic % inclusive, a oxygen content of 1 atomic % to 20 atomic % inclusive, a silicon content of 25 atomic % to 35 atomic % inclusive, and a hydrogen content of 0.1 atomic % to 10 atomic % inclusive.

[0363] The structure described in this embodiment mode can be used in appropriate combination with other embodiment modes.

[0364] (Embodiment 2) In this embodiment, an example of a method for synthesizing an organic compound that can be suitably used in a light-emitting device of one embodiment of the present invention will be described using an organic compound represented by General Formulas (G1) and (G2) as an example.

[0365] <Method for synthesizing organic compound represented by general formula (G1)> The organic compound represented by the general formula (G1) can be synthesized by a synthesis method that applies various reactions. For example, it can be synthesized by the synthesis schemes (S-1) and (S-2) shown below. Compound 1 is coupled with an arylamine (compound 2) and an arylamine (compound 3) to obtain a diamine compound (compound 4).

[0366] Subsequently, the diamine compound (compound 4), an aryl halide (compound 5), and an aryl halide (compound 6) are coupled to obtain the organic compound represented by the above general formula (G1).

[0367] [ka]

[0368] [ka]

[0369] In the above synthesis schemes (S-1) and (S-2), A represents a substituted or unsubstituted fused aromatic ring having 10 to 30 carbon atoms or a substituted or unsubstituted fused heteroaromatic ring having 10 to 30 carbon atoms; Ar 1 ~Ar 4 each independently represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 13 carbon atoms; 1 ~X 8 each independently represents any one of an alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, and a trialkylsilyl group having 3 to 12 carbon atoms. Examples of the condensed aromatic ring or condensed heteroaromatic ring include chrysene, phenanthrene, stilbene, acridone, phenoxazine, and phenothiazine. In particular, anthracene, pyrene, coumarin, quinacridone, perylene, tetracene, and naphthobisbenzofuran are preferred.

[0370] In the above synthesis schemes (S-1) and (S-2), when the Buchwald-Hartwig reaction is carried out using a palladium catalyst, X 10 ~X 13represents a halogen group or a triflate group, and the halogen is preferably iodine, bromine, or chlorine. In this reaction, palladium compounds such as bis(dibenzylideneacetone)palladium(0) and palladium(II) acetate, and ligands such as tri(tert-butyl)phosphine, tri(n-hexyl)phosphine, tricyclohexylphosphine, di(1-adamantyl)-n-butylphosphine, and 2-dicyclohexylphosphino-2',6'-dimethoxy-1,1'-biphenyl can be used. In addition, organic bases such as sodium tert-butoxide, and inorganic bases such as potassium carbonate, cesium carbonate, and sodium carbonate can be used. In addition, toluene, xylene, mesitylene, benzene, tetrahydrofuran, dioxane, and the like can be used as a solvent. It should be noted that the reagents that can be used in this reaction are not limited to these reagents.

[0371] The reaction carried out in the above synthesis schemes (S-1) and (S-2) is not limited to the Buchwald-Hartwig reaction, and may be, for example, the Migita-Kosugi-Still coupling reaction using an organotin compound, a coupling reaction using a Grignard reagent, or the Ullmann reaction using copper or a copper compound.

[0372] In the above synthesis scheme (S-1), when compound 2 and compound 3 have different structures, it is preferable to first react compound 1 with compound 2 to form a coupling product, and then react the resulting coupling product with compound 3. When compound 1 is reacted stepwise with compound 2 and compound 3, compound 1 is preferably a dihalogen product, and X 10 and X 11 It is preferred to carry out the amination reaction selectively one by one using different halogens.

[0373] Furthermore, in the synthetic scheme (S-2), when compound 5 and compound 6 have different structures, it is preferable to first react compound 4 with compound 5 to obtain a coupling product, and then further react the obtained coupling product with compound 6.

[0374] <Method for synthesizing organic compound represented by general formula (G2)> The organic compound of one embodiment of the present invention represented by General Formula (G2) can be synthesized by utilizing any organic reaction. As an example, two methods are shown below.

[0375] The first method consists of the following synthesis schemes (S-3) to (S-8). In the first step, an amine compound (compound 9) is obtained by a condensation reaction between an aniline compound (compound 7) and a 1,4-cyclohexadiene-1,4-dicarboxylic acid compound (compound 8). The process is shown in scheme (S-3). However, when two aniline compounds (compound 7) having the same substituent are condensed in one step to introduce an amino group having the same substituent, it is preferable to add two equivalents of the aniline compound (compound 7) and perform the same reaction. In that case, the target product can be obtained even if the carbonyl group of compound 8 does not have reaction selectivity.

[0376] Next, a 1,4-cyclohexadiene compound (compound 11) can be obtained by condensation reaction of an amine compound (compound 9) with an aniline derivative (compound 10). The process for obtaining compound 11 is shown in scheme (S-4).

[0377] Then, the 1,4-cyclohexadiene compound (compound 11) is oxidized in air to obtain a terephthalic acid compound (compound 12). The process for obtaining compound 12 is shown in scheme (S-5).

[0378] Next, the terephthalic acid compound (compound 12) can be condensed with an acid to obtain a quinacridone compound (compound 13). The process for obtaining compound 13 is shown in scheme (S-6).

[0379] Next, a quinacridone compound (compound 13) and an aryl halide (compound 14) are coupled to obtain a quinacridone compound (compound 15). The process for obtaining compound 15 is shown in scheme (S-7). However, when two aryl halides (compound 8) having the same substituent can be coupled in one step and an amino group having the same substituent is to be introduced, it is preferable to carry out the same reaction by adding two equivalents of an aryl halide (compound 14). In that case, the target product can be obtained even if the amino group of compound 14 does not have reaction selectivity.

[0380] Next, the quinacridone compound (compound 15) and the aryl halide (compound 16) are coupled to obtain the organic compound represented by the above general formula (G2). This process is shown in scheme (S-8).

[0381] [ka]

[0382] [ka]

[0383] The second method consists of the following synthesis schemes (S-3) to (S-5), and the following schemes (S-9), (S-10), and (S-11). The explanation of schemes (S-3) to (S-5) is as above. A diamine compound (compound 17) can be obtained by coupling a terephthalic acid compound (compound 12) with an aryl halide (compound 14). The process for obtaining compound 17 is shown in scheme (S-9). However, when two molecules of aryl halide having the same substituent can be coupled in one step and an amino group having the same substituent is introduced, it is preferable to add two equivalents of an aryl halide (compound 14) and perform the same reaction. In that case, the target product can be obtained even if the amino group of compound 12 does not have reaction selectivity.

[0384] Next, the diamine compound (compound 17) can be coupled with an aryl halide (compound 16) to obtain a diamine compound (compound 18). The process for obtaining compound 18 is shown in scheme (S-10).

[0385] Finally, the diamine compound (compound 18) is subjected to ring condensation using an acid to obtain the organic compound represented by the above general formula (G2). This process is shown in scheme (S-11). However, in the ring condensation reaction, Ar 5 or Ar 6 There is a possibility that the hydrogen at the ortho position of the above reacts to produce an isomer of the organic compound represented by the above general formula (G2).

[0386] In the scheme (S-11), by using a diamine compound (compound 18) having a symmetric structure, it is possible to synthesize the organic compound represented by the above general formula (G2).

[0387] [ka]

[0388] In the synthetic schemes (S-3) to (S-6) and (S-9) to (S-11), Al 1 represents an alkyl group such as a methyl group.

[0389] In the synthesis schemes (S-7) to (S-10), Y 1 and Y 2 represents a chlorine, bromine, iodine, or triflate group.

[0390] In the synthesis schemes (S-7) to (S-10), it is preferable to carry out the Ullmann reaction because the reaction can proceed at high temperatures and the target compound can be obtained in a relatively high yield. Examples of reagents that can be used in the reaction include copper or copper compounds, and examples of bases include inorganic bases such as potassium carbonate and sodium hydride. Examples of solvents that can be used in the reaction include 2,2,6,6-tetramethyl-3,5-heptanedione, 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)pyrimidinone (DMPU), toluene, xylene, and benzene. In the Ullmann reaction, it is preferable to use 2,2,6,6-tetramethyl-3,5-heptanedione, DMPU, and xylene, which have high boiling points, because the target product can be obtained in a shorter time and in a higher yield at a reaction temperature of 100°C or higher. In addition, it is more preferable to use DMPU because the reaction temperature is higher than 150°C. Reagents that can be used in the reaction are not limited to the above-mentioned reagents.

[0391] In the synthesis schemes (S-7) to (S-10), 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. and a ligand such as tri(tert-butyl)phosphine, tri(n-hexyl)phosphine, tricyclohexylphosphine, di(1-adamantyl)-n-butylphosphine, 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl, tri(ortho-tolyl)phosphine, (S)-(6,6'-dimethoxybiphenyl-2,2'-diyl)bis(diisopropylphosphine) (abbreviation: cBRIDP (registered trademark)) can be used. 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, toluene, xylene, benzene, tetrahydrofuran, dioxane, or the like can be used as a solvent. Reagents that can be used in this reaction are not limited to the above-mentioned reagents.

[0392] Moreover, the method for synthesizing the organic compound represented by the general formula (G2) of the present invention is not limited to the synthesis schemes (S-1) to (S-11).

[0393] R substituted on the quinacridone skeleton 1 ~R 10 Specific examples include an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a trimethylsilyl group, a triethylsilyl group, and a tributylsilyl group.

[0394] X 9 and X 10 Substituted by Ar 5 And, X 11 and X 12Substituted by Ar 6 Specific examples of the phenyl group include a 2-isopropylphenyl group, a 2-butylphenyl group, a 2-isobutylphenyl group, a 2-tert-butylphenyl group, a 2-isopropylphenyl group, a 2-butylphenyl group, a 3-propylphenyl group, a 3-isobutylphenyl group, a 3-tert-butylphenyl group, a 4-propylphenyl group, a 4-isopropylphenyl group, a 4-butylphenyl group, a 4-isobutylphenyl group, a 4-tert-butylphenyl group, a 3,5-dipropylphenyl group, a 3,5-di-iso ... Examples of such aryl groups include a 3,5-isopropylphenyl group, a 3,5-dibutylphenyl group, a 3,5-di-isobutylphenyl group, a (3,5-di-tert-butyl)phenyl group, a 1,3-dipropylphenyl group, a 1,3-di-isopropylphenyl group, a 1,3-dibutylphenyl group, a 1,3-di-isobutylphenyl group, a (1,3-di-tert-butyl)phenyl group, a 1,3,5-triisopropylphenyl group, a (1,3,5-tri-tert-butyl)phenyl group, and a 4-cyclohexylphenyl group.

[0395] The above describes the synthesis methods of the organic compounds represented by general formulas (G1) and (G2), which are one embodiment of the present invention. However, the present invention is not limited thereto, and the compounds may be synthesized by other synthesis methods.

[0396] (Embodiment 3) In this embodiment mode, a light-emitting device using the light-emitting device described in Embodiment 1 will be described with reference to FIGS. 11A and 11B. FIG.

[0397] Fig. 11A is a top view showing the light-emitting device, and Fig. 11B is a cross-sectional view taken along lines AB and CD in Fig. 11A. This light-emitting device includes a driving circuit section (source side driving circuit) 601, a pixel section 602, and a driving circuit section (gate side driving circuit) 603, all of which are shown by dotted lines to control the light emission of the light-emitting device. In addition, 604 is a sealing substrate, 625 is a desiccant, and 605 is a sealant, and the inside surrounded by the sealant 605 forms a space 607.

[0398] The lead wiring 608 is a wiring for transmitting signals input to the source side driving circuit 601 and the gate side driving circuit 603, and receives a video signal, a clock signal, a start signal, a reset signal, and the like from an FPC (flexible printed circuit) 609 serving as an external input terminal. Although only an FPC is shown here, a printed wiring board (PWB: Printed Wiring Board) may be attached to this FPC. In this specification, the light emitting device includes not only the light emitting device itself, but also a state in which an FPC or PWB is attached to it.

[0399] Next, the cross-sectional structure of the light-emitting device will be described with reference to Fig. 11B. A driving circuit section and a pixel section are formed on an element substrate 610, and here, a source side driving circuit 601, which is the driving circuit section, and one pixel in a pixel section 602 are shown.

[0400] The source side driver circuit 601 is formed as a CMOS circuit combining an n-channel TFT 623 and a p-channel TFT 624. The driver circuit may be formed of various CMOS circuits, PMOS circuits, or NMOS circuits formed with TFTs. In this embodiment, a driver integrated type in which the driver circuit is formed on the substrate is shown, but this is not necessarily required, and the driver circuit may be formed externally instead of on the substrate.

[0401] The pixel section 602 is formed of pixels including a switching TFT 611, a current control TFT 612, and a first electrode 613 electrically connected to the drain of the TFT 612. An insulator 614 is formed so as to cover an end of the first electrode 613. The insulator 614 can be formed by using a positive type photosensitive resin film.

[0402] In order to improve the coverage of the film formed on the insulator 614, a surface having a curvature is formed at the upper or lower end of the insulator 614. For example, when photosensitive acrylic is used as the material of the insulator 614, it is preferable to provide a curved surface only at the upper end of the insulator 614. The radius of curvature of the curved surface is preferably 0.2 μm or more and 0.3 μm or less. In addition, either a negative type or a positive type photosensitive material can be used as the insulator 614.

[0403] An EL layer 616 and a second electrode 617 are formed on the first electrode 613. Here, it is desirable to use a material with a large work function as the material used for the first electrode 613 that functions as an anode. For example, in addition to a single layer film such as an ITO film, an indium tin oxide film containing silicon, an indium oxide film containing 2 wt% to 20 wt% zinc oxide, a titanium nitride film, a chromium film, a tungsten film, a Zn film, or a Pt film, a laminated film of a film mainly composed of titanium nitride and aluminum, or a three-layer structure of a titanium nitride film, a film mainly composed of aluminum, and a titanium nitride film can be used. Note that a laminated structure provides low resistance as wiring, good ohmic contact, and can further function as an anode.

[0404] The EL layer 616 is formed by various methods such as a deposition method using a deposition mask, an inkjet method, a spin coating method, etc. The material constituting the EL layer 616 may be a low molecular weight compound or a high molecular weight compound (including an oligomer and a dendrimer).

[0405] Furthermore, the second electrode 617 formed on the EL layer 616 and functioning as a cathode is preferably made of a material having a small work function (Al, Mg, Li, Ca, or alloys or compounds thereof, such as MgAg, MgIn, and AlLi). When light generated in the EL layer 616 is transmitted through the second electrode 617, the second electrode 617 is preferably made of a laminate of a thin metal thin film and a transparent conductive film (ITO, indium oxide containing 2 wt% to 20 wt% zinc oxide, indium tin oxide containing silicon, zinc oxide (ZnO), or the like).

[0406] 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 Embodiments 1 and 2 and a light-emitting device having another structure.

[0407] 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, and may be filled with an inert gas (nitrogen, argon, etc.), or with a resin or a desiccant, or both.

[0408] It is preferable to use epoxy resin or glass frit for the sealing material 605. It is also preferable that these materials are as moisture and oxygen impermeable as possible. In addition to glass and quartz substrates, materials that can be used for the sealing substrate 604 include plastic substrates made of FRP (Fiber Reinforced Plastics), PVF (Polyvinyl Fluoride), polyester, acrylic, etc.

[0409] In this manner, a light emitting apparatus using the light emitting device described in the first embodiment can be obtained.

[0410] <Light-emitting device configuration example 1> FIG. 12 shows, as an example of a display device, 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.

[0411] Figure 12A illustrates a substrate 1001, a base insulating film 1002, a gate insulating film 1003, gate electrodes 1006, 1007, 1008, a first interlayer insulating film 1020, a second interlayer insulating film 1021, a peripheral portion 1042, a pixel portion 1040, a driving circuit portion 1041, first electrodes 1024W, 1024R, 1024G, 1024B of the light-emitting 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.

[0412] 12A and 12B, colored layers (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B) are provided on a transparent base material 1033. A black layer (black matrix) 1035 may be further provided. The transparent base material 1033 on which the colored layers and black layer are provided is aligned and fixed to the substrate 1001. The colored layers and black layer are covered with an overcoat layer 1036. In addition, in FIG. 12A, there are light-emitting layers from which light does not pass through the colored layers and goes out, and light-emitting layers from which light passes through the colored layers of each color and goes out. The light that does not pass through the colored layers is white, and the light that passes through the colored layers is red, blue, and green, so that an image can be expressed by four color pixels.

[0413] 12B 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. 12B, the colored layers may be provided between the substrate 1001 and the sealing substrate 1031.

[0414] Furthermore, the light-emitting device described above has a structure (bottom emission type) in which light is extracted from the substrate 1001 side on which the TFT is formed, but it may also be a light-emitting device with a structure (top emission type) in which light is extracted from the sealing substrate 1031 side.

[0415] <Configuration Example 2 of Light Emitting Device> Cross-sectional views of a top-emission type light-emitting device are shown in Figures 13A and 13B. In this case, a substrate that does not transmit light can be used as the substrate 1001. The process is the same as that of the bottom-emission type 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.

[0416] The lower electrode 1025W, the lower electrode 1025R, the lower electrode 1025G, and the lower electrode 1025B of the light-emitting device are anodes here, but may be cathodes. In addition, in the case of a top-emission type light-emitting device as shown in FIG. 13A and FIG. 13B, the lower electrode 1025W, the lower electrode 1025R, the lower electrode 1025G, and the lower electrode 1025B are preferably reflective electrodes. The second electrode 1029 preferably has a function of reflecting light and a function of transmitting light. In addition, it is preferable that the second electrode 1029 and the lower electrode 1025W, the lower electrode 1025R, the lower electrode 1025G, and the lower electrode 1025B have a function of amplifying light of a specific wavelength by applying a microcavity structure between the second electrode 1029 and the lower electrode 1025W, the lower electrode 1025R, the lower electrode 1025G, and the lower electrode 1025B. The EL layer 1028 is configured as described in the first and third embodiments, and the device structure is such that white light emission can be obtained.

[0417] 12A, 12B, 13A, and 13B, the configuration of the EL layer that can emit white light can be realized by using multiple light-emitting layers, multiple light-emitting units, etc. Note that the configuration for obtaining white light emission is not limited to these.

[0418] In the top emission structure as shown in Figures 13A and 13B, sealing can be performed with a sealing substrate 1031 provided with colored layers (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B). The sealing substrate 1031 may be provided with a black layer (black matrix) 1030 so as to be positioned between pixels. The colored layers (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B) and the black layer (black matrix) may be covered with an overcoat layer. Note that a light-transmitting substrate is used as the sealing substrate 1031.

[0419] Also, while Fig. 13A shows a configuration in which a full-color display is performed using three colors, red, green, and blue, as shown in Fig. 13B, a full-color display may be performed using four colors, red, green, blue, and white. Also, the configuration in which a full-color display is performed is not limited to this. For example, a full-color display may be performed using four colors, red, green, blue, and yellow.

[0420] A light-emitting device according to one embodiment of the present invention uses a fluorescent material as a guest material. The fluorescent material has a sharper spectrum than a phosphorescent material, and therefore light emission with high color purity can be obtained. 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.

[0421] In this manner, a light emitting apparatus using the light emitting device described in the first and third embodiments can be obtained.

[0422] Note that this embodiment mode can be appropriately combined with other embodiment modes.

[0423] (Embodiment 4) In this embodiment, an electronic device and a display device according to one embodiment of the present invention will be described.

[0424] According to one embodiment of the present invention, an electronic device and a display device having a flat surface, high emission efficiency, and high reliability can be manufactured. According to one embodiment of the present invention, an electronic device and a display device having a curved surface, high emission efficiency, and high reliability can be manufactured. In addition, a light-emitting device with high color reproducibility can be obtained as described above.

[0425] Examples of electronic devices include television sets, desktop or notebook personal computers, computer monitors, digital cameras, digital video cameras, digital photo frames, mobile phones, portable game machines, personal digital assistants, audio playback devices, and large game machines such as pachinko machines.

[0426] A portable information terminal 900 shown in FIGS. 14A and 14B includes a housing 901, a housing 902, a display portion 903, a hinge portion 905, and the like.

[0427] Housings 901 and 902 are connected by a hinge portion 905. Portable information terminal 900 can be unfolded from a folded state (FIG. 14A) to an unfolded state as shown in FIG. 14B. This allows for excellent portability when carried around, and excellent visibility due to the large display area when in use.

[0428] A portable information terminal 900 has a flexible display unit 903 that spans a housing 901 and a housing 902 that are connected by a hinge unit 905 .

[0429] A light-emitting device manufactured according to one embodiment of the present invention can be used for the display portion 903. In this way, a highly reliable portable information terminal can be manufactured.

[0430] 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.

[0431] When the mobile information terminal 900 is unfolded, the display portion 903 is held in a state in which the radius of curvature is large. For example, the display portion 903 is held including a curved portion with a radius of curvature of 1 mm to 50 mm, preferably 5 mm to 30 mm. In part of the display portion 903, pixels are continuously arranged from the housing 901 to the housing 902, and a curved display can be performed.

[0432] The display unit 903 functions as a touch panel and can be operated with a finger, a stylus, or the like.

[0433] The display unit 903 is preferably configured as a single flexible display. This allows continuous display without interruption between the housing 901 and the housing 902. Note that each of the housing 901 and the housing 902 may be provided with a display.

[0434] It is preferable that the hinge section 905 has a locking mechanism so that the angle between the housing 901 and the housing 902 does not become larger than a predetermined angle when the mobile information terminal 900 is unfolded. For example, the angle at which the lock is applied (the housing does not open any further) is preferably equal to or greater than 90 degrees and less than 180 degrees, and typically can be 90 degrees, 120 degrees, 135 degrees, 150 degrees, or 175 degrees. This can improve the convenience, safety, and reliability of the mobile information terminal 900.

[0435] If the hinge section 905 has a locking mechanism, excessive force is not applied to the display section 903, and damage to the display section 903 can be prevented. Therefore, a highly reliable portable information terminal can be realized.

[0436] The housing 901 and the housing 902 may each include a power button, an operation button, an external connection port, a speaker, a microphone, and the like.

[0437] Either the housing 901 or the housing 902 is provided with a wireless communication module, and data can be transmitted and received via a computer network such as the Internet, a LAN (Local Area Network), or Wi-Fi (registered trademark).

[0438] A portable information terminal 910 shown in FIG. 14C 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.

[0439] A light-emitting device manufactured according to one embodiment of the present invention can be used for the display portion 912. This enables portable information terminals to be manufactured with high yield.

[0440] The mobile information terminal 910 has a touch sensor on a display unit 912. Any operation, such as making a call or inputting characters, can be performed by touching the display unit 912 with a finger, a stylus, or the like.

[0441] In addition, by operating the operation button 913, it is possible to turn the power on and off, and to switch the type of image displayed on the display unit 912. For example, it is possible to switch from a mail creation screen to a main menu screen.

[0442] Furthermore, by providing a detection device such as a gyro sensor or an acceleration sensor inside the mobile information terminal 910, the orientation (portrait or landscape) of the mobile information terminal 910 can be determined and the orientation of the screen display on the display unit 912 can be automatically switched. The orientation of the screen display can also be switched by touching the display unit 912, by operating the operation button 913, or by voice input using the microphone 916.

[0443] The mobile information terminal 910 has one or more functions selected from, for example, a telephone, a notebook, or an information viewing device. Specifically, it can be used as a smartphone. The mobile information terminal 910 can execute various applications such as mobile phone, e-mail, text viewing and creation, music playback, video playback, Internet communication, and games.

[0444] 14D includes a housing 921, a display unit 922, operation buttons 923, a shutter button 924, etc. In addition, the camera 920 has a detachable lens 926 attached thereto.

[0445] A light-emitting device manufactured according to one embodiment of the present invention can be used for the display portion 922. In this way, a highly reliable camera can be manufactured.

[0446] 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.

[0447] The camera 920 can capture still images or moving images by pressing a shutter button 924. The display unit 922 also has a function as a touch panel, and an image can also be captured by touching the display unit 922.

[0448] The camera 920 may be equipped with a strobe device, a viewfinder, and the like, or these may be incorporated into the housing 921.

[0449] FIG. 15A is a schematic diagram showing an example of a cleaning robot.

[0450] The cleaning robot 5100 has a display 5101 arranged on the top surface, a plurality of cameras 5102 arranged on the side surface, a brush 5103, and an operation button 5104. Although not shown, the bottom surface of the cleaning robot 5100 is provided with tires, a suction port, and the like. The cleaning robot 5100 also has various sensors such as an infrared sensor, an ultrasonic sensor, an acceleration sensor, a piezoelectric sensor, an optical sensor, and a gyro sensor. The cleaning robot 5100 also has wireless communication means.

[0451] The cleaning robot 5100 can move by itself, detect dirt 5120, and suck up the dirt from a suction port provided on the bottom surface.

[0452] In addition, the cleaning robot 5100 can analyze the image captured by the camera 5102 and determine the presence or absence of obstacles such as walls, furniture, steps, etc. Furthermore, when an object that may become entangled in the brush 5103, such as a wire, is detected by image analysis, the rotation of the brush 5103 can be stopped.

[0453] The remaining battery level, the amount of sucked up dirt, etc. can be displayed on the display 5101. The route traveled by the cleaning robot 5100 may be displayed on the display 5101. The display 5101 may be a touch panel, and an operation button 5104 may be provided on the display 5101.

[0454] The cleaning robot 5100 can communicate with a portable electronic device 5140 such as a smartphone. Images captured by the camera 5102 can be displayed on the portable electronic device 5140. Therefore, the owner of the cleaning robot 5100 can know the state of the room even when he or she is away from home. Also, the display on the display 5101 can be confirmed on the portable electronic device 5140 such as a smartphone.

[0455] The light-emitting device according to one embodiment of the present invention can be used for the display 5101 .

[0456] The robot 2100 shown in FIG. 15B includes a computing device 2110, an illuminance sensor 2101, a microphone 2102, an upper camera 2103, a speaker 2104, a display 2105, a lower camera 2106, an obstacle sensor 2107, and a movement mechanism 2108.

[0457] The microphone 2102 has a function of detecting the user's voice, environmental sounds, etc. The speaker 2104 has a function of emitting sound. The robot 2100 can communicate with the user using the microphone 2102 and the speaker 2104.

[0458] The display 2105 has a function of displaying various information. The robot 2100 can display information desired by the user on the display 2105. The display 2105 may be equipped with a touch panel. The display 2105 may also be a removable information terminal, and by installing it in a fixed position on the robot 2100, charging and data transfer are possible.

[0459] The upper camera 2103 and the lower camera 2106 have a function of capturing images of the surroundings of the robot 2100. In addition, the obstacle sensor 2107 can detect the presence or absence of an obstacle in the direction of travel when the robot 2100 moves forward using the moving mechanism 2108. The robot 2100 can recognize the surrounding environment and move safely using the upper camera 2103, the lower camera 2106, and the obstacle sensor 2107.

[0460] The light-emitting device according to one embodiment of the present invention can be used for the display 2105 .

[0461] 15C 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, operation keys (including a power switch or an operation switch), a connection terminal 5006, a sensor 5007 (including a function of measuring force, displacement, position, speed, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared), a microphone 5008, a second display unit 5002, a support unit 5012, an earphone 5013, and the like.

[0462] 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 .

[0463] 16A and 16B 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. 16A shows the mobile information terminal 5150 in an unfolded state. Fig. 16B shows the mobile information terminal 5150 in a folded state. Although the mobile information terminal 5150 has a large display area 5152, it is compact and highly portable when folded.

[0464] Display area 5152 can be folded in half by bending portion 5153. Bending portion 5153 is composed of an expandable member and a plurality of support members, and when folding, the expandable member stretches and bending portion 5153 is folded with a radius of curvature of 2 mm or more, preferably 5 mm or more.

[0465] 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.

[0466] This embodiment mode can be combined with other embodiment modes as appropriate.

[0467] (Embodiment 5) 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. 17. 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.

[0468] 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.

[0469] 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 an automobile, and lighting can be provided in a windshield, a ceiling, or the like, for example.

[0470] FIG. 17 shows an example in which the light-emitting device is used as an indoor lighting device 8501. Since the light-emitting device can be enlarged, a large-area lighting device can be formed. In addition, by using a housing having a curved surface, a lighting device 8502 in which the light-emitting region has a curved surface can 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 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.

[0471] Furthermore, by using the light-emitting device on the front surface of a table, the lighting device 8504 can function as a table. By using the light-emitting device in part of other furniture, the lighting device can function as furniture.

[0472] In the above manner, a lighting device and an electronic device can be obtained by applying the light-emitting device of one embodiment of the present invention. Note that the applicable lighting device and electronic device are not limited to those described in this embodiment, and the lighting device and electronic device can be used in any field.

[0473] The structure described in this embodiment mode can be used in appropriate combination with structures described in other embodiment modes. [Explanation of symbols]

[0474] 101: electrode, 101a: conductive layer, 101b: conductive layer, 102: electrode, 103: electrode, 103a: conductive layer, 103b: conductive layer, 104: electrode, 104a: conductive layer, 104b: conductive layer, 106: light-emitting unit, 108: light-emitting unit, 111: hole injection layer, 112: hole transport layer, 113: electron transport layer, 115: charge generation layer, 116: hole injection layer, 117: hole transport layer, 118: electron transport layer, 119: electron injection layer, 130: light-emitting layer, 131: compound, 132: compound, 133: compound, 134: compound, 135: compound, 135_1: compound, 135_2: Compound, 136: Compound, 137: Compound, 140: Electron injection layer, 145: Partition, 150: Light emitting device, 152: Light emitting device, 170: Light emitting layer, 200: Substrate, 220: Substrate, 222B: Region, 222G: Region, 222R: Region, 223: Light shielding layer, 224B: Optical element, 224G: Optical element, 224R: Optical element, 301: Guest material, 302: Guest material, 310: Luminophore, 320: Protective 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 unit, 905: hinge unit, 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, 1044R: red pixel, 1044G: green pixel, 1044B: blue 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: moving mechanism, 21 10: arithmetic unit, 5000: housing, 5001: display unit, 5002: display unit, 5003: speaker, 5004: LED lamp, 5006: connection terminal, 5007: sensor, 5008: microphone, 5012: support unit, 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 portion, 8501: lighting device, 8502: lighting device, 8503: lighting device, 8504: lighting device,

Claims

1. A pair of electrodes, and a first light-emitting unit, a second light-emitting unit, and a charge generating layer between the pair of electrodes; the first light-emitting unit is located between one of the pair of electrodes and the charge generating layer, the second light-emitting unit is located between the other of the pair of electrodes and the charge generating layer, the first light-emitting unit has a first light-emitting layer; the first light-emitting layer comprises a first material and a second material; the first material is a TADF material or a phosphorescent material; the second material has a function of converting singlet excitation energy into luminescence, and has a luminophore and two or more diarylamino groups; the luminophore is a fused aromatic ring or a fused heteroaromatic ring; the fused aromatic ring or the fused heteroaromatic ring is bonded to the two or more diarylamino groups, each of the aryl groups in the two or more diarylamino groups independently has at least two protecting groups; the protecting group has any one of an alkyl group having from 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having from 3 to 10 carbon atoms, or a trialkylsilyl group having from 3 to 12 carbon atoms; A light emitting device, wherein light emission is obtained from the second material.

2. In claim 1, A light-emitting device wherein the diarylamino group is a diphenylamino group.

3. A pair of electrodes, and a first light-emitting unit, a second light-emitting unit, and a charge generating layer between the pair of electrodes; the first light-emitting unit is located between one of the pair of electrodes and the charge generating layer, the second light-emitting unit is located between the other of the pair of electrodes and the charge generating layer, the first light-emitting unit has a first light-emitting layer; the first light-emitting layer comprises a first material and a second material; the first material is a TADF material or a phosphorescent material; the second material has a function of converting singlet excitation energy into luminescence, and has a luminophore and two or more diphenylamino groups; the luminophore is a fused aromatic ring or a fused heteroaromatic ring; the condensed aromatic ring or the condensed heteroaromatic ring is bonded to the two or more diphenylamino groups, the phenyl groups in the two or more diphenylamino groups each independently have a protecting group at the 3-position and the 5-position; each of the protecting groups independently has any one of an alkyl group having from 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having from 3 to 10 carbon atoms, or a trialkylsilyl group having from 3 to 12 carbon atoms; A light emitting device, wherein light emission is obtained from the second material.

4. In any one of claims 1 to 3, The light emitting device wherein the alkyl group is a branched chain alkyl group.

5. In claim 4, A light emitting device, wherein the branched alkyl group has a quaternary carbon.

6. In any one of claims 1 to 5, The fused aromatic ring or the fused heteroaromatic ring comprises any one of naphthalene, anthracene, fluorene, chrysene, triphenylene, tetracene, pyrene, perylene, coumarin, quinacridone, and naphthobisbenzofuran.

7. In any one of claims 1 to 6, the second light-emitting unit has a second light-emitting layer; the second light-emitting layer comprises a second phosphorescent material; A light emitting device, wherein the light emission is derived from the second phosphorescent material.

8. In claim 7, A light-emitting device, wherein the peak wavelength in the emission spectrum of the second phosphorescent material is longer than the peak wavelength in the emission spectrum of the second material.

9. A light emitting device according to any one of claims 1 to 8; An electronic device having at least one of a housing or a display unit.

10. A light emitting device according to any one of claims 1 to 8; A lighting device having a housing.

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