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

Abstract

To provide a light-emitting element with high luminous efficiency and reliability.SOLUTION: A light-emitting element includes a material that operates as an energy donor and a light-emitting material in a light-emitting layer. The material that operates as the energy donor has a function of converting triplet excited energy into light emission, and the light-emitting material emits fluorescence. The molecular structure of the light-emitting material has a structure of including a chromophore and a protective group, and five or more protective groups are included in one molecule of a guest material. By introducing the protective group in the molecule, the energy shift of the triplet excited energy by a dexter mechanism from the material that operates as the energy donor to the light-emitting material is suppressed. As the protective group, an alkyl group or a branched chain alkyl group is used. Light emission is obtained from both the light-emitting material and the material that operates as the energy donor.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] One aspect of the present invention relates to a light-emitting element, or a display device, an electronic device, an organic compound, and a lighting device having the light-emitting element. Note that one aspect of the present invention is not limited to the above technical field. The technical field of one aspect of the invention disclosed in this specification and the like relates to an article, a method, or a manufacturing method. Or, one aspect 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 aspect of the present invention disclosed in this specification include semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, lighting devices, power storage devices, storage devices, driving methods thereof, or manufacturing methods thereof.

[0002] Note that one aspect of the present invention is not limited to the above technical field. The technical field of one aspect of the invention disclosed in this specification and the like relates to an article, a method, or a manufacturing method. Or, one aspect 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 aspect of the present invention disclosed in this specification include semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, lighting devices, power storage devices, storage devices, driving methods thereof, or manufacturing methods thereof. Note that one aspect of the present invention is not limited to the above technical field. The technical field of one aspect of the invention disclosed in this specification and the like relates to an article, a method, or a manufacturing method. Or, one aspect 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 aspect of the present invention disclosed in this specification include semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, lighting devices, power storage devices, storage devices, driving methods thereof, or manufacturing methods thereof. Note that one aspect of the present invention is not limited to the above technical field. The technical field of one aspect of the invention disclosed in this specification and the like relates to an article, a method, or a manufacturing method. Or, one aspect 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 aspect of the present invention disclosed in this specification include semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, lighting devices, power storage devices, storage devices, driving methods thereof, or manufacturing methods thereof. Note that one aspect of the present invention is not limited to the above technical field. The technical field of one aspect of the invention disclosed in this specification and the like relates to an article, a method, or a manufacturing method. Or, one aspect 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 aspect of the present invention disclosed in this specification include semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, lighting devices, power storage devices, storage devices, driving methods thereof, or manufacturing methods thereof. Note that one aspect of the present invention is not limited to the above technical field. The technical field of one aspect of the invention disclosed in this specification and the like relates to an article, a method, or a manufacturing method. Or, one aspect 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 aspect of the present invention disclosed in this specification include semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, lighting devices, power storage devices, storage devices, driving methods thereof, or manufacturing methods thereof. Note that one aspect of the present invention is not limited to the above technical field. The technical field of one aspect of the invention disclosed in this specification and the like relates to an article, a method, or a manufacturing method. Or, one aspect 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 aspect of the present invention disclosed in this specification include semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, lighting devices, power storage devices, storage devices, driving methods thereof, or manufacturing methods thereof. Note that one aspect of the present invention is not limited to the above technical field. The technical field of one aspect of the invention disclosed in this specification and the like relates to an article, a method, or a manufacturing method. Or, one aspect 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 aspect of the present invention disclosed in this specification include semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, lighting devices, power storage devices, storage devices, driving methods thereof, or manufacturing methods thereof.

Background Art

[0003] In recent years, research and development of light-emitting elements using electroluminescence (EL) have been actively conducted. The basic configuration of these light-emitting elements is a configuration in which a layer (EL layer) containing a light-emitting substance is sandwiched between a pair of electrodes. By applying a voltage between the electrodes of this element, light emission from the light-emitting substance can be obtained. In recent years, research and development of light-emitting elements using electroluminescence (EL) have been actively conducted. The basic configuration of these light-emitting elements is a configuration in which a layer (EL layer) containing a light-emitting substance is sandwiched between a pair of electrodes. By applying a voltage between the electrodes of this element, light emission from the light-emitting substance can be obtained. In recent years, research and development of light-emitting elements using electroluminescence (EL) have been actively conducted. The basic configuration of these light-emitting elements is a configuration in which a layer (EL layer) containing a light-emitting substance is sandwiched between a pair of electrodes. By applying a voltage between the electrodes of this element, light emission from the light-emitting substance can be obtained. In recent years, research and development of light-emitting elements using electroluminescence (EL) have been actively conducted. The basic configuration of these light-emitting elements is a configuration in which a layer (EL layer) containing a light-emitting substance is sandwiched between a pair of electrodes. By applying a voltage between the electrodes of this element, light emission from the light-emitting substance can be obtained.

[0004] Since the above-described light-emitting element is self-luminous, a display device using this element has advantages such as excellent visibility, no need for a backlight, and low power consumption. Furthermore, it also has advantages such as being able to be manufactured in a thin and lightweight manner and having a high response speed. Since the above-described light-emitting element is self-luminous, a display device using this element has advantages such as excellent visibility, no need for a backlight, and low power consumption. Furthermore, it also has advantages such as being able to be manufactured in a thin and lightweight manner and having a high response speed. Since the above-described light-emitting element is self-luminous, a display device using this element has advantages such as excellent visibility, no need for a backlight, and low power consumption. Furthermore, it also has advantages such as being able to be manufactured in a thin and lightweight manner and having a high response speed.

[0005] An organic compound is used as the light-emitting substance, and an EL layer containing the light-emitting organic compound is sandwiched between a pair of electrodes. In the case of a light-emitting element (e.g., an organic EL element) provided with a layer, when a voltage is applied between a pair of electrodes, electrons are injected from the cathode and holes are injected from the anode into the light-emitting EL layer respectively, and a current flows. Then, by the recombination of the injected electrons and holes, the light-emitting organic compound is excited, and light emission can be obtained from the excited light-emitting organic compound.

[0006] As types of excited states formed by organic compounds, there are singlet excited states (S * ) and triplet excited states (T * ). Light emission from singlet excited states is called fluorescence, and light emission from triplet excited states is called phosphorescence. Also, their statistical generation ratio in the light-emitting element is S :T * = * = 1:3. Therefore, it is possible to obtain higher luminous efficiency for a light-emitting element using a compound that emits phosphorescence (phosphorescent material) than for a light-emitting element using a compound that emits fluorescence (fluorescent material). Thus, in recent years, the development of light-emitting elements using phosphorescent materials capable of converting the energy of triplet excited states into light emission has been actively carried out. Among light-emitting elements using phosphorescent materials, especially in light-emitting elements that exhibit blue light emission, it is difficult to develop stable compounds having high triplet excitation energy levels, and thus they have not yet reached practical use. Therefore, the development of light-emitting elements using more stable fluorescent materials has been carried out, and methods for increasing the luminous efficiency of light-emitting elements using fluorescent materials (fluorescent light-emitting elements) have been explored.

[0007] Among light-emitting elements using phosphorescent materials, especially in light-emitting elements that exhibit blue light emission, since it is difficult to develop stable compounds having high triplet excitation energy levels, they have not yet reached practical use. Therefore, the development of light-emitting elements using more stable fluorescent materials has been carried out, and methods for increasing the luminous efficiency of light-emitting elements using fluorescent materials (fluorescent light-emitting elements) have been explored. Therefore, the development of light-emitting elements using more stable fluorescent materials has been carried out, and methods for increasing the luminous efficiency of light-emitting elements using fluorescent materials (fluorescent light-emitting elements) have been explored. Therefore, the development of light-emitting elements using more stable fluorescent materials has been carried out, and methods for increasing the luminous efficiency of light-emitting elements using fluorescent materials (fluorescent light-emitting elements) have been explored.

[0008] Materials that can convert part or all of the energy of triplet excited states into light emission and ​​​Thus, in addition to phosphorescent materials, thermally activated delayed fluorescence (TADF) materials are known. In TAD F materials, singlet excited states are generated from triplet excited states by reverse intersystem crossing, and are converted into light emission from the singlet excited states.

[0009] In a light-emitting device using a TADF material, in order to enhance the light-emitting efficiency, it is important that not only singlet excited states are efficiently generated from triplet excited states in the TADF material, but also efficient light emission is obtained from the singlet excited states, that is, the fluorescence quantum yield is high. However, it is difficult to design a light-emitting material that satisfies both of these conditions.

[0010] Further, 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 (see Patent Document 1).

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Non-Patent Documents

[0012]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0013] Multi-color light-emitting devices typified by white light-emitting devices are light-emitting devices expected to be applied to displays and the like. As an element configuration for obtaining such a multi-color light-emitting device, there is a light-emitting device (also referred to as a tandem device) provided with a plurality of EL layers via a charge generation layer. Since different light-emitting colors can be used for different EL layers in the tandem device, it is suitable for fabricating a multi-color light-emitting device. However, since the tandem device has a large number of layers, there is a problem of a large number of manufacturing steps. Therefore, there is a demand for a light-emitting device capable of obtaining a plurality of light-emitting colors from a single EL layer. When obtaining a plurality of light-emitting colors, two or more light-emitting materials are used in the light-emitting layer. From the viewpoint of reliability, the development of a multi-color light-emitting device using a fluorescent material is demanded.

[0014] As described above, for example, in order to improve the efficiency of a fluorescent light-emitting device, in a light-emitting layer having a host material and a guest material, after converting the triplet excitons of the host material into singlet excitons, the singlet excitation energy is transferred to a fluorescent material in the guest material. However, the process of converting the triplet excitation energy of the host material into singlet excitation energy competes with the process of deactivating the triplet excitation energy. Therefore, the triplet excitation energy of the host material may not be sufficiently converted into singlet excitation energy. For example, as a deactivation path of the triplet excitation energy, when a fluorescent material is used as a guest material in the light-emitting layer of a light-emitting device, a deactivation path in which the triplet excitation energy of the host material moves to the lowest triplet excitation energy level (T1 level) of the fluorescent material can be considered.

[0015] As described above, for example, in order to improve the efficiency of a fluorescent light-emitting device, in a light-emitting layer having a host material and a guest material, after converting the triplet excitons of the host material into singlet excitons, the singlet excitation energy is transferred to a fluorescent material in the guest material. However, the process of converting the triplet excitation energy of the host material into singlet excitation energy competes with the process of deactivating the triplet excitation energy. Therefore, the triplet excitation energy of the host material may not be sufficiently converted into singlet excitation energy. For example, as a deactivation path of the triplet excitation energy, when a fluorescent material is used as a guest material in the light-emitting layer of a light-emitting device, a deactivation path in which the triplet excitation energy of the host material moves to the lowest triplet excitation energy level (T1 level) of the fluorescent material can be considered. However, the process of converting the triplet excitation energy of the host material into singlet excitation energy competes with the process of deactivating the triplet excitation energy. Therefore, the triplet excitation energy of the host material may not be sufficiently converted into singlet excitation energy. For example, as a deactivation path of the triplet excitation energy, when a fluorescent material is used as a guest material in the light-emitting layer of a light-emitting device, a deactivation path in which the triplet excitation energy of the host material moves to the lowest triplet excitation energy level (T1 level) of the fluorescent material can be considered. Therefore, the triplet excitation energy of the host material may not be sufficiently converted into singlet excitation energy. For example, as a deactivation path of the triplet excitation energy, when a fluorescent material is used as a guest material in the light-emitting layer of a light-emitting device, a deactivation path in which the triplet excitation energy of the host material moves to the lowest triplet excitation energy level (T1 level) of the fluorescent material can be considered. For example, as a deactivation path of the triplet excitation energy, when a fluorescent material is used as a guest material in the light-emitting layer of a light-emitting device, a deactivation path in which the triplet excitation energy of the host material moves to the lowest triplet excitation energy level (T1 level) of the fluorescent material can be considered. When a fluorescent material is used as a guest material in the light-emitting layer of a light-emitting device, a deactivation path in which the triplet excitation energy of the host material moves to the lowest triplet excitation energy level (T1 level) of the fluorescent material can be considered. This is a possible deactivation path. ​Since energy transfer via the deactivation pathway does not contribute to luminescence, the luminescence efficiency of the fluorescent light-emitting device is low. This leads to the following.

[0016] Therefore, in order to increase the luminescence efficiency of the fluorescent light-emitting element and improve its reliability, it is preferable that the triplet excitation energy in the light-emitting layer can be efficiently converted into singlet excitation energy, and that the triplet excitation energy can be efficiently transferred as singlet excitation energy to the fluorescent light-emitting material. For this reason, there is a need to develop a technique for efficiently generating the singlet excited state of the guest material from the triplet excited state of the host material, further improving the luminescence efficiency of the light-emitting element, and improving its reliability. ...and the triplet excitation energy can be efficiently transferred as singlet excitation energy to the fluorescent light-emitting material. For this reason, there is a need to develop a technique for efficiently generating the singlet excited state of the guest material from the triplet excited state of the host material, further improving the luminescence efficiency of the light-emitting element, and improving its reliability. ...efficiently generate the singlet excited state of the guest material from the triplet excited state of the host material, further improve the luminescence efficiency of the light-emitting element, and improve its reliability. ...generate the singlet excited state of the guest material from the triplet excited state of the host material, further improve the luminescence efficiency of the light-emitting element, and improve its reliability. ...generate the singlet excited state of the guest material from the triplet excited state of the host material, further improve the luminescence efficiency of the light-emitting element, and improve its reliability.

[0017] Therefore, in one aspect of the present invention, an object is to provide a light-emitting element capable of obtaining a plurality of emission colors from a single EL layer. In one aspect of the present invention, an object is to provide a light-emitting element having high luminescence efficiency. Or, in one aspect of the present invention, an object is to provide a light-emitting element having high reliability. Or, in one aspect of the present invention, an object is to provide a light-emitting element with reduced power consumption. Or, in one aspect of the present invention, an object is to provide a novel light-emitting element. Or, in one aspect of the present invention, an object is to provide a novel light-emitting device. Or, in one aspect of the present invention, an object is to provide a novel display device. ...a light-emitting element having high luminescence efficiency. ...a light-emitting element having high reliability. ...a light-emitting element with reduced power consumption. ...a novel light-emitting element. ...a novel light-emitting device. ...a novel display device.

[0018] Note that the description of the above problems does not prevent the existence of other problems. Note that one aspect of the present invention does not necessarily need to solve all of these problems. Other problems will be apparent from the description in the specification and the like, and it is possible to extract other problems from the description in the specification and the like. ...from the description in the specification and the like, and it is possible to extract other problems from the description in the specification and the like. ...from the description in the specification and the like, and it is possible to extract other problems from the description in the specification and the like. ...from the description in the specification and the like, and it is possible to extract other problems from the description in the specification and the like.

Means for Solving the Problems

[0019] As described above, in a light-emitting element that exhibits fluorescence, triplet excitation energy is efficiently converted into light emission. Therefore, the development of a method for converting energy between materials used in the light-emitting layer is required. To achieve this, it is necessary to improve the dynamic efficiency of the energy donor-energy accessor system. It is necessary to suppress the transfer of triplet excitation energy between the photons via the Dexter mechanism.

[0020] Therefore, one embodiment of the present invention is a light-emitting element having a light-emitting layer between a pair of electrodes, A first material having a function of converting triplet excitation energy into light emission, and a second material having a function of converting singlet excitation energy into light emission. The second material has a function of converting the energy into light emission, and the second material has a luminophore and five or more The luminophore has the above protecting group, and the luminophore is a condensed aromatic ring or a condensed heteroaromatic ring, and has 5 or more protecting groups. are each independently an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted alkyl group having 3 A cycloalkyl group having 3 to 10 carbon atoms, or a trialkylsilyl group having 3 to 12 carbon atoms. The light-emitting element has either one of the first material and the second material and emits light from both the first material and the second material.

[0021] In the above structure, at least four of the five or more protecting groups are independently selected from the group having three carbon atoms. Alkyl groups with 10 or more carbon atoms, substituted or unsubstituted cycloalkyl groups with 3 or more carbon atoms and 10 or less carbon atoms and a trialkylsilyl group having 3 to 12 carbon atoms.

[0022] Another embodiment of the present invention is a light-emitting element having a light-emitting layer between a pair of electrodes, The present invention relates to a first material that converts triplet excitation energy into light emission, and a second material that converts singlet excitation energy into light emission. It has a second material having a function of converting a triplet excited state energy into light emission, and the second material has a light emitting group and at least four protecting groups, the light emitting group is a condensed aromatic ring or a condensed heteroaromatic ring, and the four protecting groups are not directly bonded to the condensed aromatic ring or the condensed heteroaromatic ring, and the four protecting groups are each independently an alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, or any one of a trialkylsilyl group having 3 to 12 carbon atoms, and it is a light emitting device in which light emission is obtained from both the first material and the second material. Also, another aspect of the present invention is a light emitting device having a light emitting layer between a pair of electrodes, and the light emitting layer

[0023] has a first material having a function of converting triplet excited state energy into light emission and a second material having a function of converting singlet excited state energy into light emission, the second material has a light emitting group and two or more diarylamino groups, the light emitting group is a condensed aromatic ring or a condensed heteroaromatic ring, the condensed aromatic ring or the condensed heteroaromatic ring is bonded to two or more diarylamino groups, and the two or more diarylamino groups each independently have at least one protecting group, and the protecting groups each independently have, an alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, or any one of a trialkylsilyl group having 3 to 12 carbon atoms, and it is a light emitting device in which light emission is obtained from both the first material and the second material. Also, another aspect of the present invention is a light emitting device having a light emitting layer between a pair of electrodes, and the light emitting layer has a first material having a function of converting triplet excited state energy into light emission and a second material having a function of converting singlet excited state energy into light emission, the second material has a light emitting group and two or more diarylamino groups, the light emitting group is a condensed aromatic ring or a condensed heteroaromatic ring, and the condensed aromatic ring or the condensed heteroaromatic ring is bonded to two or more diarylamino groups, and the two or more diarylamino

[0024] groups each independently have at least one protecting group, and the protecting groups each independently have, an alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, or any one of a trialkylsilyl group having 3 to 12 carbon atoms, and it is a light emitting device in which light emission is obtained from both the first material and the second material. Having a diarylamino group above, the light-emitting group is a condensed aromatic ring or a condensed heteroaromatic ring, and the condensed aromatic ring or condensed heteroaromatic ring is bonded to two or more diarylamino groups, and the two or more diary lamino groups each independently have at least two protecting groups, and the protecting groups each indep endently 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, and a trialkylsilyl group having 3 to 12 carbon atoms, and is a light-emitting element capable of obtaining light emission from both the first material and the second material.

[0025] Further, in the above configuration, it is preferable that the diarylamino group is a diphenylamino group.

[0026] Further, in the above configuration, it is preferable that the alkyl group is a branched-chain alkyl group.

[0027] Another aspect of the present invention is a light-emitting element having a light-emitting layer between a pair of electrodes, and the light-emitting layer has a first material having a function of converting triplet excitation energy into light emission and a second material having a function of converting singlet excitation energy into light emission. The second material has a light-emitting group and a plurality of protecting groups. The light-emitting group is a condensed aromatic ring or a condensed heteroaromatic ring, and at least one of the atoms constituting the plurality of protecting groups is located directly above one surface of the condensed aromatic ring or the condensed heteroaromatic ring and at least one of the atoms constituting the plurality of protecting groups is located directly above the other surface of the condensed aromatic ring or the condensed hetero aromatic ring, and it is a light-emitting element capable of obtaining light emission from both the first material and the second material.

[0028] Another aspect of the present invention is a light-emitting element having a light-emitting layer between a pair of electrodes, and the light-emitting layer has a first material having a function of converting triplet excitation energy into light emission and a singlet excitation energy​​ It has a second material having a function of converting light emission into light, and the second material has a light-emitting group and two or more diphenylamino groups. The light-emitting group is a condensed aromatic ring or a condensed heteroaromatic ring, and the condensed aromatic ring or the condensed heteroaromatic ring is bonded to two or more diphenylamino groups, and the phenyl groups in the two or more diphenyl amino groups each independently have a protecting group at the 3-position and the 5-position, and the protecting group each independently has 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. It is a light-emitting element capable of obtaining light emission from both the first material and the second material.

[0029] Further, in the above configuration, it is preferable that the alkyl group is a branched-chain alkyl group.

[0030] Further, in the above configuration, it is preferable that the branched-chain alkyl group has a quaternary carbon.

[0031] Further, in the above configuration, it is preferable that the condensed aromatic ring or the condensed heteroaromatic ring contains any one of naphthalene, anthracene, fluorene, chrysene, triphenylene, pyrene, tetracene, perylene, coumarin quinacridone, naphthobisbenzofuran.

[0032] Further, in the above configuration, the first material has a first organic compound and a second organic compound, and it is preferable that the first organic compound and the second organic compound form an exciplex. It is more preferable that the first organic compound exhibits phosphorescence emission.

[0033] Further, in the above configuration, it is preferable that the peak wavelength of the emission spectrum of the first material is located on the shorter wavelength side than the peak wavelength of the emission spectrum of the second material.

[0034] Further, in the above configuration, it is preferable that the first material is a compound exhibiting phosphorescence or delayed fluorescence. Preferably.

[0035] Further, in the above configuration, it is preferable that the emission spectrum of the first material overlaps with the absorption band on the longest wavelength side of the absorption spectrum of the second material. Preferably.

[0036] Further, in the above configuration, it is preferable that the concentration of the second material in the light-emitting layer is 0.01 wt% or more and 2 wt% or less. Preferably.

[0037] Another aspect of the present invention is a display device including the light-emitting element having each of the above configurations and at least one of a color filter or a transistor. Further, another aspect of the present invention is an electronic device including the display device and at least one of a housing or a touch sensor. Preferably. Preferably. Another aspect of the present invention is a lighting device including the light-emitting element having each of the above configurations and at least one of a housing or a touch sensor. Also, one aspect of the present invention includes not only a light-emitting device having a light-emitting element but also an electronic device having a light-emitting device. Therefore, the light-emitting device described in this specification refers to an image display device or a light source (including a lighting device). Further, a display module in which a connector, for example, an FPC (Flexible Printed Circuit), a TCP (Tape Carrier Package) is attached to the light-emitting element, a display module in which a printed wiring board is provided at the tip of the TCP, or a display module in which an IC (integrated circuit) is directly mounted on the light-emitting element by a COG (Chip On Glass) method may be included in the light-emitting device. Preferably. Preferably. Preferably. Preferably. Preferably. Preferably. Preferably. Preferably.

Advantages of the Invention

[0038] According to one aspect of the present invention, there is provided a light-emitting device capable of obtaining a plurality of emission colors from a single EL layer. According to one aspect of the present invention, a light-emitting device with high luminous efficiency can be provided. Alternatively, in one aspect of the present invention, a highly reliable light-emitting device can be provided. Alternatively, According to one aspect of the present invention, a light-emitting device with reduced power consumption can be provided. Alternatively, According to one aspect of the present invention, a novel light-emitting device can be provided. Alternatively, according to one aspect of the present invention, a novel light-emitting device can be provided. Alternatively, according to one aspect of the present invention, a novel display device can be provided.

[0039] Note that the description of these effects does not prevent the existence of other effects. Note that one aspect of the present invention does not necessarily have to have all of these effects. Note that other effects can be naturally understood from the descriptions in the specification, drawings, claims, etc., and it is possible to extract these other effects from the descriptions in the specification, drawings, claims, etc.

Brief Description of Drawings

[0040]

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Embodiments for Carrying Out the Invention

[0041] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and its form and details can be variously changed without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description of the embodiments shown below in terms of content. It is not construed as being limited to the content of the embodiments described below.

[0042] In addition, in the drawings and the like, the position, size, range, etc. of each component shown may not represent the actual position, size, range, etc. for the sake of simplicity of understanding. For this reason, the disclosed invention is not necessarily limited to the position, size, range, etc. disclosed in the drawings and the like. Also, in this specification and the like, ordinal numbers such as first, second, etc. are used for convenience,

[0043] and may not indicate the process order or the stacking order. Therefore, for example, "the first" may be "the second" or the like. It can be described by appropriately replacing it with "third" or the like. Also, when the ordinal numbers described in this specification and the like do not match the ordinal numbers used to specify an aspect of the present invention there may be a case.

[0044] Also, in this specification and the like, when explaining the configuration of the invention using drawings, the reference signs indicating the same thing may be commonly used even between different drawings.

[0045] Also, in this specification and the like, the term "film" and the term "layer" can be interchanged with each other. 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" in some cases.

[0046] Also, in this specification and the like, the singlet excited state (S * ) is a singlet state having excitation energy. Also, the S1 level is the lowest level of the singlet excitation energy levels and is the excitation energy level of the lowest singlet excited state (S1 state). Also, the triplet excited state (T ) is a triplet state having excitation energy. Also, the T1 level * is the lowest level of the triplet excitation energy levels and is the excitation energy level of the lowest triplet excited state (T1 state). Note that in this specification and the like, even when simply expressed as the singlet excited state and the singlet excitation energy level, it may represent the S1 state and the S1 level. Also, even when expressed as the triplet excited state and the triplet excitation energy level in some cases, it may represent the T1 state and the T1 level.

[0047] ​​​​In addition, in this specification and the like, a fluorescent material is a compound that emits light in the visible light region when relaxing from the singlet excited state to the ground state. A phosphorescent material is a compound that emits light in the visible light region at room temperature when relaxing from the triplet excited state to the ground state. In other words, a phosphorescent material is one of the compounds that can convert triplet excitation energy into visible light.

[0048] Note that in this specification and the like, room temperature refers to a temperature in the range of 0°C or higher and 40°C or lower.

[0049] In addition, in this specification and the like, the blue wavelength region is 400 nm or more and less than 490 nm, and blue light emission has at least one emission spectrum peak in this wavelength region. Also, the green wavelength region is 490 nm or more and less than 580 nm, and green light emission has at least one emission spectrum peak in this wavelength region. Also, the red wavelength region is 580 nm or more and 680 nm or less, and red light emission has at least one emission spectrum peak in this wavelength region. Also, even when two emission spectra each have an emission spectrum peak in the same wavelength region, if the peak wavelengths are different, the two emission spectra may be regarded as emissions of different colors. Note that the emission spectrum peak includes a maximum value or a shoulder.

[0050] (Embodiment 1) In this embodiment, a light-emitting element according to one aspect of the present invention will be described below with reference to FIGS. 1 to 6.

[0051] <Configuration Example of Light-Emitting Element> First, the configuration of a light-emitting element according to one aspect of the present invention will be described below with reference to FIG. 1.

[0052] FIG. 1(A) is a schematic cross-sectional view of a light-emitting element 150 according to one embodiment of the present invention.

[0053] The light-emitting element 150 has a pair of electrodes (electrode 101 and electrode 102), and an EL layer 100 provided between the pair of electrodes. The EL layer 100 has at least a light-emitting layer 130. .

[0054] In addition, the EL layer 100 shown in FIG. 1(A) has functional layers such as a hole injection layer 111, a hole transport layer 112, an electron transport layer 118, and an electron injection layer 119 in addition to the light-emitting layer 130.

[0055] In the present embodiment, among the pair of electrodes, electrode 101 is described as the anode and electrode 102 is described as the cathode. However, the configuration of the light-emitting element 150 is not limited thereto. That is, electrode 101 may be the cathode, electrode 102 may be the anode, and the stacking order of the layers between the electrodes may be reversed. That is, from the anode side, the hole injection layer 111, the hole transport layer 112, the light-emitting layer 130, the electron transport layer 118, and the electron injection layer 119 may be stacked in this order. .

[0056] Note that the configuration of the EL layer 100 is not limited to the configuration shown in FIG. 1(A), and may be a configuration having at least one selected from the hole injection layer 111, the hole transport layer 112, the electron transport layer 118, and the electron injection layer 119. Alternatively, the EL layer 100 may have a functional layer having a function such as reducing a hole or electron injection barrier, improving hole or electron transportability, inhibiting hole or electron transportability, or suppressing a quenching phenomenon caused by an electrode. Note that each functional layer may be a single layer or a structure in which a plurality of layers are stacked.

[0057] <Light-emitting mechanism of the light-emitting element> Next, the light-emitting mechanism of the light-emitting layer 130 will be described below.

[0058] In the light-emitting element 150 according to one aspect of the present invention, by applying a voltage between a pair of electrodes (electrode 101 and electrode 102 ), electrons are injected from the cathode and holes are injected from the anode into the EL layer 100, respectively, and a current flows. Among the excitons generated by the recombination of carriers (electrons and holes), the ratio of singlet excitons to triplet excitons (hereinafter, exciton generation probability) is 1:3 according to statistical probability. That is, since the ratio of singlet excitons generated is 25% and the ratio of triplet excitons generated is 75%, it is important to make the triplet excitons contribute to light emission in order to improve the light emission efficiency of the light-emitting element. Therefore, it is preferable to use a material having a function of converting triplet excitation energy into light emission in the light-emitting layer 13 0. As a material having a function of converting triplet excitation energy into light emission, compounds that can emit phosphorescence (hereinafter, also referred to as phosphorescent materials) can be mentioned. In this specification and the like, a phosphorescent

[0059] material refers to a compound that exhibits phosphorescence and does not exhibit fluorescence in any temperature range from low temperature (for example, 77K) to room temperature or lower (that is, 77K or higher and 313 K or lower). The phosphorescent material preferably has a metal element with a large spin-orbit interaction. Specifically, a transition metal element is preferable, and in particular, a platinum group element (ruthenium (Ru), rhodium (Rh) ), palladium (Pd), osmium (Os), iridium (Ir), or platinum (Pt) ) is preferably included. Among them, having iridium can make the singlet ground state and triplet states ). It is preferable that the transition probability related to the direct transition to the excited state can be increased.

[0060] In addition, examples of materials having a function of converting triplet excitation energy into light emission include TADF materials. Note that a TADF material is a material in which the difference between the S1 level and the T1 level is small, and energy can be converted from triplet excitation energy to singlet excitation energy by reverse intersystem crossing. Therefore, upconversion (reverse intersystem crossing) from triplet excitation energy to singlet excitation energy is possible with a small amount of thermal energy, and the singlet excited state can be efficiently generated. In addition, an exciplex (also referred to as an exciplex, an exciplex, or an exciplex) that forms an excited state with two types of substances has a function as a TADF material in which the difference between the S1 level and the T1 level is extremely small and triplet excitation energy can be converted into singlet excitation energy.

[0061] Note that as an index of the T1 level, a phosphorescence spectrum observed at low temperature (for example, 10 K) may be used. As a TADF material, a tangent is drawn at the short-wavelength side skirt of the fluorescence spectrum at room temperature or low temperature, and the energy of the wavelength of the extrapolated line is taken as the S1 level. A tangent is drawn at the short-wavelength side skirt of the phosphorescence spectrum, and the energy of the wavelength of the extrapolated line is taken as the T1 level. In this case, it is preferable that the difference between S1 and T1 is 0.2 eV or less.

[0062] In addition, examples of materials having a function of converting triplet excitation energy into light emission include nanostructures of transition metal compounds having a perovskite structure. In particular, nanostructures of metal halide perovskites are preferable. Examples of the nanostructure include nanoparticles and nanorods. is preferred.

[0063] FIG. 1(B) is a schematic cross-sectional view showing the light-emitting layer 130 of a light-emitting element which is one aspect of the present invention. In one aspect of the present invention, the light-emitting layer 130 has a compound 131 and a compound 132. The compound 13 1 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. In order to obtain a highly reliable light-emitting element, it is preferable to use a fluorescent material as the compound 1 32. Here, in the light-emitting layer 130, the compound 131 functions as an energy donor, and the compound 132 functions as an energy acceptor. That is, in FIG. 1(C), the host material functions as an energy donor, and the guest material functions as an energy acceptor. Further, in the light-emitting element of one aspect of the present invention, since the compound 131 has a function of converting triplet excitation energy into light emission as described above, light emission from the compound 131 which is an energy donor and light emission from the compound 132 which is an energy acceptor can be obtained from the light-emitting layer 130. As described above, a light-emitting element using a fluorescent material as an energy donor having a function of converting triplet excitation energy into light emission and as an energy acceptor may be referred to as a triplet-sensitized element in this specification.

[0064] <Configuration Example 1 of Light-Emitting Layer> FIG. 1(C) is an example of the correlation of energy levels in the light-emitting layer in a light-emitting element of one aspect of the present invention. In this configuration example, the case where a TADF material is used for the compound 131 is shown.

[0065] Further, the correlation of the energy levels between the compound 131 and the compound 132 in the light-emitting layer 130 ​​​​​The relevant content is shown in Fig. 1(C). The notations and symbols in Fig. 1(C) are as follows. ·Host(131): Compound 131 ·Guest(132): Compound 132 ·T C1 : The T1 level of Compound 131 ·S C1 : The S1 level of Compound 131 ·S G : The S1 level of Compound 132 ·T G : The T1 level of Compound 132

[0066] Here, pay attention to 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 up-conversion (Fig. 1(C) Route A1). The singlet excitation energy possessed by Compound 131 can move to Compound 132 . (Fig. 1(C) Route A2). At this time, it is preferable that S ≧S C1 ≧S G . Here, the process of Route A2 competes with the emission process of Compound 131 (the transition from the S1 level of Compound 131 to the ground state). That is, the singlet excitation energy possessed by Compound 131 is converted into the emission of Compound 131 and the emission of Compound 132. Therefore, a light-emitting device of one aspect of the present invention can obtain two types of emissions, namely, the emission from Compound 131 and the emission from Compound 132. Incidentally, the singlet excitation energy of Compound 131 generated by current excitation is also similarly converted into the emissions of Compound 131 and Compound 132. Specifically, a tangent is drawn at the short-wavelength side skirt of the fluorescence spectrum of Compound 131, and the energy of the wavelength of the extrapolation line is S .

[0067] C1and when the energy of the absorption edge of the absorption spectrum of Compound 132 is S it is preferable that S G satisfies S C1 ≧S G . Further, the emission spectrum of Compound 131 preferably overlaps with the absorption band on the longest wavelength side of the absorption spectrum of Compound 132 .

[0068] The triplet excitation energy generated in Compound 131 undergoes energy transfer to the S1 level of Compound 132, which is the host material, via the above Route A1 and Route A2, and Compound 132 emits light , whereby the triplet excitation energy can be efficiently converted into fluorescence emission. In Route A 2, Compound 131 functions as an energy donor and Compound 132 functions as an energy acceptor . Further, in the light-emitting element of one embodiment of the present invention, Compound 131 functions as an energy donor and also functions as a light-emitting material .

[0069] In order for Compound 131 to function as an energy donor and also function as a light-emitting material , the concentration of Compound 132 with respect to Compound 131 is preferably 0.01 wt% or more and 2 wt% or less . With this configuration, the excitation energy of Compound 131 can be efficiently converted into the emission of Compound 1 31 and the emission of Compound 132, so that an efficient multicolor light-emitting element can be obtained. Further, by adjusting the concentrations of Compound 131 and Compound 132 , the emission color can be adjusted

[0070] Also, as shown in FIG. 1(C), the S1 level of Compound 131 is higher than the S1 level of Compound 132 . Therefore, the emission spectrum from Compound 131 is on the shorter wavelength side than that of Compound 132 is obtained. More specifically, the peak wavelength of the emission spectrum of Compound 131 is located on the shorter wavelength side than the peak wavelength of the emission spectrum of Compound 13 2. By adopting such a configuration, energy can be efficiently transferred from Compound 131 to Compound 132, and a multicolor light-emitting device with good luminous efficiency can be obtained.

[0071] Here, in the light-emitting layer 130, Compound 131 and Compound 132 are mixed. Therefore, the triplet excitation energy of Compound 131 competes with the above Routes A1 and A2, and the process in which the triplet excitation energy of Compound 131 is converted into the triplet excitation energy of Compound 132 (Route A3 in Fig. 1(C)) occurs and can be obtained. Since Compound 132 is a fluorescent material, the triplet excitation energy of Compound 132 does not contribute to light emission. That is, when the energy transfer of Route A3 occurs, the luminous efficiency of the light-emitting device decreases. In actuality, the energy transfer from T to T (Route A3) is not direct, and there may be a path in which the energy is first transferred to a triplet excited state higher than T C1 of Compound 132 and then becomes T G through internal conversion, but the process is omitted in the figure for simplicity. The undesirable thermal deactivation process hereinafter in this specification, that is, the deactivation process to T G is the same in all cases and then becomes T G through internal conversion, but the process is omitted in the figure . The undesirable thermal deactivation process hereinafter in this specification, that is, the deactivation process to T G is the same in all cases .

[0072] Here, as an intermolecular energy transfer mechanism, the Förster mechanism (dipole-dipole interaction) and the Dexter mechanism (electron exchange interaction) are known. Since Compound 132, which is an energy acceptor , is a fluorescent material, the energy transfer of Route A3 is dominated by the Dexter mechanism. Generally, the Dexter mechanism is the energy donor Compound 131 ​ A significant distance of less than 1 nm occurs with the compound 132 which is an energy acceptor. 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.

[0073] In addition, the energy transfer from the singlet excitation energy level (S C1 ) of the compound 131 to the triplet excitation energy level (T G ) of the compound 132 is not shown because the direct transition from the singlet ground state to the triplet excited state in the compound 132 is forbidden and it is difficult to become the main energy transfer process.

[0074] T in Fig. 1(C) G is often an energy level derived from the lumophore in the energy acceptor. Therefore, more specifically, in order to suppress Route A3, it is important to increase the distance between the lumophores of the energy donor and the energy acceptor.

[0075] Therefore, the inventors have found that by using a fluorescent material having a protecting group for increasing the distance from the energy donor as the energy acceptor, it is possible to suppress the decrease in the above-mentioned luminous efficiency.

[0076] <Concept of a fluorescent material having a protecting group> Fig. 2(A) shows a case where a fluorescent material without a protecting group, which is a general fluorescent material, is dispersed in a host material as a guest material, and Fig. 2(B) shows a conceptual diagram of a case where a fluorescent material having a protecting group used in a light-emitting device according to an aspect of the present invention is dispersed in a host material as a guest material. The host material may be regarded as an energy donor, and the guest material as an energy acceptor. Here, the protecting group has a function of increasing the distance between the lumophore and the host material. In Fig. , the guest material 301 has a lumophore 310. On the other hand, in Fig. 2(B), the guest material 302 has a lumophore 310 and a protecting group 320. Also, in Figs. 2(A) and (B), the guest materials 301 and 302 are surrounded by a host material 330. In Fig. 2(A), since the distance between the lumophore and the host material is short, as the energy transfer from the host material 330 to the guest material 301, both Förster energy transfer (route A4 in Figs. 2(A) and (B)) and Dexter energy transfer (route A5 in Figs. 2(A) and (B)) may occur. When the energy transfer of the triplet excitation energy from the host material to the guest material occurs by the Dexter mechanism and the 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 contributes to a decrease in the emission efficiency. On the other hand, in Fig. 2(B), the guest material 302 has a protecting group 320. Therefore, the distance between the lumophore 310 and the host material 330 can be increased. Thus, the energy transfer by the Dexter mechanism (route A5) can be suppressed. Here, in order for the guest material 302 to emit light, since the Dexter mechanism is suppressed, the guest material 302 must receive energy from the host material 330 by the Förster mechanism. That is, while suppressing the energy transfer by the Dexter mechanism, the Förster mechanism is utilized.

[0077] On the other hand, in Fig. 2(B), since the guest material 302 has a protecting group 320, the distance between the lumophore 310 and the host material 330 can be increased. Therefore, the energy transfer by the Dexter mechanism (route A5) can be suppressed. Thus, the energy transfer by the Dexter mechanism (route A5) can be suppressed. Here, in order for the guest material 302 to emit light, since the Dexter mechanism is suppressed, the guest material 302 must receive energy from the host material 330 by the Förster mechanism. That is, while suppressing the energy transfer by the Dexter mechanism, the Förster

[0078] mechanism is utilized. That is, while suppressing the energy transfer by the Dexter mechanism, the Förster mechanism is utilized. That is, while suppressing the energy transfer by the Dexter mechanism, the Förster mechanism is utilized. That is, while suppressing the energy transfer by the Dexter mechanism, the Förster It is preferable to efficiently utilize energy transfer by a mechanism. Energy transfer by the Förster mechanism is also known to be affected by the distance between the host material and the guest material. Generally, when the distance between the host material 330 and the guest material 302 is 1 nm or less, the Dexter mechanism becomes dominant, and when it is more than 1 nm and 10 nm or less, the Förster mechanism becomes dominant. Generally, when the distance between the host material 330 and the guest material 302 is 10 nm or more, energy transfer is less likely 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 lumophore 310.

[0079] Therefore, it is preferable that the protecting group 320 extends in the range of 1 nm or more and 10 nm or less from the lumophore 310. More preferably, it is 1 nm or more and 5 nm or less. With this configuration, while suppressing energy transfer by the Dexter mechanism from the host material 330 to the guest material 302, energy transfer by the Förster mechanism can be efficiently utilized. Therefore, a light-emitting device having high luminous efficiency can be manufactured.

[0080] In the light-emitting device according to one aspect of the present invention, a guest material having a protecting group on a lumophore is used in the light-emitting layer. While suppressing energy transfer by the Dexter mechanism, energy transfer by the Förster mechanism can be efficiently utilized. Therefore, a light-emitting device according to one aspect of the present invention can obtain a light-emitting device having high luminous efficiency. Furthermore, by using a material having a function of converting triplet excitation energy into light as the host material, a fluorescent light-emitting device having high luminous efficiency Since the host material can be made to have a high reliability, a light-emitting element can be manufactured. It is also possible to obtain light emission from a material that has the function of converting the utilized triplet excitation energy into light emission. This allows the production of multicolor light-emitting devices with a single light-emitting layer, which would normally require stacking light-emitting layers. can be obtained.

[0081] Here, the term "luminophore" refers to an atomic group (skeleton) that causes light emission in a fluorescent material. The photophores generally have pi bonds and preferably contain aromatic rings, and may be fused aromatic or fused rings. In another embodiment, the luminophore has a transition on the ring plane. It can be considered as a group of atoms (skeleton) containing aromatic rings on which the dipole vector exists. When one fluorescent material has a plurality of condensed aromatic rings or condensed heteroaromatic rings, the plurality of condensed aromatic rings or heteroaromatic rings may be The aromatic ring or the condensed heteroaromatic ring is selected from the group consisting of a skeleton having the lowest S1 level and a structure having the lowest S1 level. In addition, the longest one of the plurality of condensed aromatic rings or condensed heteroaromatic rings may be considered as a group. The skeleton having an absorption edge on the wavelength side may be considered as the luminophore of the fluorescent material. The shape of the emission spectrum of each of the condensed aromatic rings or condensed heteroaromatic rings of the fluorescent material can be used to determine the In some cases it may be possible to predict the luminophores.

[0082] The condensed aromatic ring or condensed heteroaromatic ring may be a phenanthrene skeleton, a stilbene skeleton, an acyclic skeleton, or a cyclic heteroaromatic ring. Examples of the skeleton include lysine skeleton, phenoxazine skeleton, and phenothiazine skeleton. In particular, naphthalene skeleton is skeleton, anthracene skeleton, fluorene skeleton, chrysene skeleton, triphenylene skeleton, tetra Cene skeleton, pyrene skeleton, perylene skeleton, coumarin skeleton, quinacridone skeleton, naphthobisbe A fluorescent material having a benzofuran skeleton is preferred because it has a high fluorescence quantum yield.

[0083] In addition, the substituent used as a protecting group should have a triplet excitation energy level higher than the T1 energy levels of the lumophore and the host material. Therefore, it is preferable to use a saturated hydrocarbon group. This is because substituents without π bonds have high triplet excitation energy levels. Also, substituents without π bonds have a low function of transporting carriers (electrons or holes). Therefore, a saturated hydrocarbon group can increase the distance between the lumophore and the host material with little impact on the excited state or carrier transportability of the host material. In an organic compound having both a substituent without a π bond and a substituent having a π-conjugated system, the frontier orbitals {HOMO (Highest Occupied Molecular Orbital, also referred to as the highest occupied orbital) and LUMO (Lowest Unoccupied Molecular Orbital, also referred to as the lowest unoccupied orbital)} often exist on the side of the substituent having the π-conjugated system, especially when the lumophore has frontier orbitals. As will be described later, for energy transfer by the Dexter mechanism, the overlap of the HOMOs and the overlap of the LUMOs of the energy donor and the energy acceptor are important. Therefore, by using a saturated hydrocarbon group as the protecting group, the distance between the frontier orbitals of the host material as the energy donor and the frontier orbitals of the guest material as the energy acceptor can be increased, and energy transfer by the Dexter mechanism can be suppressed. Specific examples of the protecting group include alkyl groups having 1 to 10 carbon atoms. Also, since the protecting group needs to increase the distance between the lumophore and the host material, a bulky substituent is preferable.

[0084] ​​​​​​​​​​​​​​​Therefore, 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 can be preferably used. In particular, as the alkyl group, a bulky branched-chain alkyl group is preferable. Further, the substituent is particularly preferable because it becomes a bulky substituent when it has a quaternary carbon.

[0085] Also, it is preferable that there are 5 or more protecting groups for one lumophore. With this configuration, the entire lumophore can be covered with the protecting groups, so that the distance between the host material and the lumophore can be appropriately adjusted. In addition, in Fig. 2(B), the state where the lumophore and the protecting group are directly bonded is shown, but it is more preferable that the protecting group is not directly bonded to the lumophore. For example, the protecting group may be bonded to the lumophore via a divalent or higher substituent such as an arylene group or an amino group. By bonding the protecting group to the lumophore via the substituent, the distance between the lumophore and the host material can be effectively increased. Therefore, when the lumophore and the protecting group are not directly bonded, if there are 4 or more protecting groups for one lumophore, the energy transfer by the Dexter mechanism can be effectively suppressed.

[0086] Also, the divalent or higher substituent connecting the lumophore and the protecting group is preferably a substituent having a π-conjugated system. With this configuration, physical properties such as the emission color, HOMO level, and glass transition point of the guest material can be adjusted. Note that it is preferable that the protecting group is arranged on the outermost side when viewing the molecular structure with the lumophore as the center.

[0087] <Fluorescent material having a protecting group and molecular structure example> Here, it can be used for the light-emitting element of one embodiment of the present invention represented by the following structural formula (102). The fluorescent material, N,N'-[(2-tert-butylanthracene)-9,10- diyl]-N,N'-bis(3,5-di-tert-butylphenyl)amine (abbreviation: 2 tBu-mmtBuDPhA2Anth) is shown. In 2tBu-mmtBuDPhA 2Anth, the anthracene ring is the lumophore, and the tertiary butyl group (tBu group ) acts as a protecting group.

[0088]

Chemical Structure

[0089] The display of the above 2tBu-mmtBuDPhA2Anth by a ball-and-stick model is shown in Fig. 3(B). Note that Fig. 3(B) shows the state when 2tBu-mmtBuDPhA2Anth is viewed from the direction of the arrow in Fig. 3(A) (horizontal direction with respect to the anthracene ring plane). The shaded part in Fig. 3(B) represents the part directly above the anthracene ring plane which is the lumophore, and it can be seen that there is a region where the tBu group which is the protecting group overlaps with the directly above part. For example, in Fig. 3(B), the atom indicated by the arrow (a ) is the carbon atom of the tBu group that overlaps with the shaded part, and the atom indicated by the arrow (b) is the hydrogen atom of the tBu group that overlaps with the shaded part. That is, in 2tBu-mmtB uDPhA2Anth, atoms constituting the protecting group are located directly above one side of the lumophore plane, and atoms constituting the protecting group are also located directly above the other plane. By adopting such a configuration, even when the guest material is in a state dispersed in the host material, the distance between the anthracene ring which is the lumophore and the host material can be increased in both the planar direction and the vertical direction of the anthracene ring, and energy transfer by the Dexter mechanism can be suppressed. That is, in both the planar and vertical directions of the anthracene ring, the distance between the anthracene ring and the host material can be increased, and energy transfer by the Dexter mechanism can be suppressed.

[0090] In addition, for energy transfer by the Dexter mechanism, for example, when the transition involved in energy transfer is a transition between the HOMO and the LUMO, the overlap of the HOMOs of the host material and the guest material and the overlap of the LUMOs of the host material and the guest material are important. When the HOMOs and LUMOs 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 HOMOs and LUMOs of both materials. Specifically, it is important to increase the distance between the skeleton related to the excited state and the host material. Here, in fluorescent materials, both the HOMO and the LUMO often have a lumophore. For example, when the HOMO and LUMO of the guest material spread above and below the plane of the lumophore (in 2tBu-mmtBuDPhA2Anth, above and below the anthracene ring), it is important in the molecular structure to cover above and below the plane of the lumophore with a protecting group. In addition, a condensed aromatic ring or a condensed heteroaromatic ring that functions as a lumophore such as a pyrene ring or an anthracene ring has a transition dipole vector on the plane of the ring. Therefore, in Fig. 3(B), it is preferable that 2tBu-mmtBuDPhA2Anth has a region where the tBu group, which is a protecting group, overlaps directly above the plane where the transition dipole vector exists, that is, directly above the plane of the anthracene ring. Specifically, at least one of the atoms constituting the plurality of protecting groups (the tBu group in Figs. 3(A) and 3(B)) is located directly above one surface of the condensed aromatic ring or the condensed heteroaromatic ring (the anthracene ring in Figs. 3(A) and 3(B)), and at least one of the atoms constituting the plurality of protecting groups is located directly above the other surface of the condensed aromatic ring or the condensed heteroaromatic ring. With this configuration, in the case where the HOMO and LUMO of the guest material spread above and below the plane of the lumophore (in 2tBu-mmtBuDPhA2Anth, above and below the anthracene ring), it is important in the molecular structure to cover above and below the plane of the lumophore with a protecting group. in 2tBu-mmtBuDPhA2Anth, when it spreads above and below the plane of the anthracene ring), it is important in the molecular structure to cover above and below the plane of the anthracene ring with a protecting group. covering above and below the plane of the lumophore with a protecting group is important in the molecular structure.

[0091] In addition, a condensed aromatic ring or a condensed heteroaromatic ring that functions as a lumophore such as a pyrene ring or an anthracene ring has a transition dipole vector on the plane of the ring. Therefore, in Fig. 3(B), it is preferable that 2tBu-mmtBuDPhA2Anth has a region where the tBu group, which is a protecting group, overlaps directly above the plane where the transition dipole vector exists, that is, directly above the plane of the anthracene ring. Specifically, at least one of the atoms constituting the plurality of protecting groups (the tBu group in Figs. 3(A) and 3(B)) is located directly above one surface of the condensed aromatic ring or the condensed heteroaromatic ring (the anthracene ring in Figs. 3(A) and 3(B)), and at least one of the atoms constituting the plurality of protecting groups is located directly above the other surface of the condensed aromatic ring or the condensed heteroaromatic ring. Therefore, in Fig. 3(B), 2tBu-mmtBuDPhA2Anth preferably has a region where the tBu group, which is a protecting group, overlaps directly above the plane where the transition dipole vector exists, that is, directly above the plane of the anthracene ring. Specifically, at least one of the atoms constituting the plurality of protecting groups (the tBu group in Figs. 3(A) and 3(B)) is located directly above one surface of the condensed aromatic ring or the condensed heteroaromatic ring (the anthracene ring in Figs. 3(A) and 3(B)), and at least one of the atoms constituting the plurality of protecting groups is located directly above the other surface of the condensed aromatic ring or the condensed heteroaromatic ring. That is, at least one of the atoms constituting the plurality of protecting groups (the tBu group in Figs. 3(A) and 3(B)) is located directly above one surface of the condensed aromatic ring or the condensed heteroaromatic ring (the anthracene ring in Figs. 3(A) and 3(B)), and at least one of the atoms constituting the plurality of protecting groups is located directly above the other surface of the condensed aromatic ring or the condensed heteroaromatic ring. That is, at least one of the atoms constituting the plurality of protecting groups (the tBu group in Figs. 3(A) and 3(B)) is located directly above one surface of the condensed aromatic ring or the condensed heteroaromatic ring (the anthracene ring in Figs. 3(A) and 3(B)), and at least one of the atoms constituting the plurality of protecting groups is located directly above the other surface of the condensed aromatic ring or the condensed heteroaromatic ring. That is, at least one of the atoms constituting the plurality of protecting groups (the tBu group in Figs. 3(A) and 3(B)) is located directly above one surface of the condensed aromatic ring or the condensed heteroaromatic ring (the anthracene ring in Figs. 3(A) and 3(B)), and at least one of the atoms constituting the plurality of protecting groups is located directly above the other surface of the condensed aromatic ring or the condensed heteroaromatic ring. That is, at least one of the atoms constituting the plurality of protecting groups (the tBu group in Figs. 3(A) and 3(B)) is located directly above one surface of the condensed aromatic ring or the condensed heteroaromatic ring (the anthracene ring in Figs. 3(A) and 3(B)), and at least one of the atoms constituting the plurality of protecting groups is located directly above the other surface of the condensed aromatic ring or the condensed heteroaromatic ring. By doing so, even when the guest material is dispersed in the host material, the distance between the lumophore and the host material can be increased, and energy transfer by the Dexter mechanism can be suppressed. Also, it is preferable that tBu groups are arranged so as to cover a lumophore such as an anthracene ring.

[0092] <Configuration Example 2 of Light-Emitting Layer> FIG. 4(C) is an example of the correlation of energy levels in the light-emitting layer 130 of the light-emitting element 150 according to one aspect of the present invention. The light-emitting layer 130 shown in FIG. 4(A) includes a compound 131, a compound 132, and further a compound 133. In one aspect of the present invention, the compound 132 is preferably a fluorescent material. Also, in this configuration example, the compounds 131 and 133 are a combination that forms an exciplex.

[0093] The combination of the compound 131 and the compound 133 may be any combination capable of forming an exciplex, but it is more preferable that one 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 easy to form a donor-acceptor type exciplex, and an exciplex can be efficiently formed. Also, when the combination of the compound 131 and the compound 133 is a combination of a compound having hole-transporting property and a compound having electron-transporting property, the carrier balance can be easily controlled by the mixing ratio. Specifically, the range of compound having hole-transporting property:compound having electron-transporting property = 1:9 to 9:1 (weight ratio) is preferable. Also, since the carrier balance can be easily controlled by having this configuration, the carrier recombination region can also be easily controlled. ​​​​​

[0094] 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 LUM O level of one is higher than the LUMO level of the other. Note that the HOMO level of Compound 131 may be equal to the HOMO level of Compound 133, or the LUMO level of Compound 1 33 may be equal to the LUMO level of Compound 133.

[0095] The LUMO level and HOMO level of a compound can be derived from the electrochemical properties (reduction potential and oxidation potential) of the compound measured by cyclic voltammetry (C V) measurement.

[0096] For example, when Compound 131 has hole transporting properties and Compound 133 has electron transporting properties, as shown in the energy band diagram of FIG. 4(B), it is preferable that the HOMO level of Compound 131 is higher than the HOMO level of Compound 1 33, and it is preferable that the LUMO level of Compound 131 is higher than the LUMO level of Compound 13 3. With such a correlation of energy levels, holes and electrons, which are carriers injected from a pair of electrodes (electrode 101 and electrode 102), are easily injected into Compound 131 and Compound 133, respectively, which is preferable.

[0097] In FIG. 4(B), Comp(131) represents Compound 131, Comp(1 33) represents Compound 133, ΔE C1 represents the energy difference between the LUMO level and the HOMO level of Compound 131, and ΔE C3 represents the energy difference between the LUMO level and the HOMO level of Compound 133, and ΔE ​E represents the energy difference between the LUMO level of Compound 133 and the HOMO level of Compound 131, in notation and sign.

[0098] In addition, the exciplex formed by Compound 131 and Compound 133 is an exciplex that has the HOMO molecular orbital of Compound 131 and the LUMO molecular orbital of Compound 133. Also, the excitation energy of this exciplex is approximately equivalent to the energy difference (ΔE ) between the LUMO level of Compound 133 and the HOMO E level of Compound 131, and is smaller than the energy difference (ΔE ) between the LUMO level and the HOMO C1 level of Compound 131 and the energy difference (ΔE ) between the LUMO level and the HOMO level of Compound 133. Therefore, by forming an exciplex with Compound 131 and Compound 133, C3 it is possible to form an excited state with a lower excitation energy. Also, since it has a lower excitation energy, this exciplex can form a stable excited state.

[0099] In addition, the energy level correlation among Compound 131, Compound 132, and Compound 133 in the light-emitting layer 130 is shown in FIG. 4(C). The notations and signs in FIG. 4(C) 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 : S1 level of Compound 133 ·SG : S1 level of Compound 132 ·T G : T1 level of Compound 132 ·S E : S1 level of the exciplex ·T E : T1 level of the exciplex

[0100] In the light-emitting element according to one embodiment of the present invention, an exciplex is formed between Compound 131 and Compound 1 33 included in the light-emitting layer 130. The S1 level (S E ) of the exciplex and the T1 level (T E ) of the exciplex are adjacent energy levels to each other (see Route A6 in Fig. 4(C)).

[0101] Since the excitation energy levels (S E and T E ) of the exciplex are lower than the S1 levels (S and S C1 and S C3 ) of each substance (Compound 131 and Compound 133) forming the exciplex, it is possible to form an excited state with a lower excitation energy. As a result, the driving voltage of the light-emitting element 150 can be reduced.

[0102] The S1 level (S E ) and the T1 level (T E ) of the exciplex are adjacent energy levels to each other and thus easily undergo reverse intersystem crossing and have TADF properties. Therefore, the exciplex has a function of converting triplet excitation energy into singlet excitation energy by upconversion (Route A7 in Fig. 4(C)). The singlet excitation energy possessed by the exciplex can quickly move to Compound 132. (Route A8 in Fig. 4(C)). At this time, it is preferable that S ≧S In Route A8, the exciplex is the energy donor and the compound E ≧S G is the energy acceptor. In Route A8, the exciplex is the energy donor and the compound​​ 132 functions as an energy acceptor. Here, the process of route A8 is the luminescence process of the exciplex (transition from the S1 level of the exciplex to the ground state or transition from the T1 level of the exciplex to the ground state). That is, the singlet and triplet excitation energies possessed by the exciplex are converted into the luminescence of the exciplex and the luminescence of compound 132. Therefore, the light-emitting device of one embodiment of the present invention can obtain luminescence from the exciplex and luminescence from compound 132.

[0103] Since the exciplex functions as an energy donor and also as a light-emitting material, the concentration of compound 132 is preferably 0.01 wt% or more and 2 wt% or less with respect to the total amount of compound 131 and compound 133. With this configuration, the excitation energy of the exciplex can be efficiently converted into the luminescence of the exciplex and the luminescence of compound 132, so that an efficient multi-color light-emitting device can be obtained. Also, by adjusting the concentrations of compound 131, compound 132, and compound 133, the emission color can be adjusted.

[0104] Specifically, a tangent is drawn at the short-wavelength side skirt of the fluorescence spectrum of the exciplex, and the energy of the wavelength of the extrapolated line is defined as S And when the energy of the wavelength at the absorption edge of the absorption spectrum of compound 132 is defined as S E and the energy of the wavelength at the absorption edge of the absorption spectrum of compound 132 is defined as S and the energy of the wavelength at the absorption edge of the absorption spectrum of compound 132 is defined as S G and the energy of the wavelength at the absorption edge of the absorption spectrum of compound 132 is defined as S E it is preferable that S G ≧ S Also, the luminescence spectrum of the exciplex preferably overlaps with the absorption band on the longest wavelength side of the absorption spectrum of compound 132.

[0105] In addition, to enhance the TADF property of the exciplex, the T 1 levels of both compound 131 and compound 133, that is, TC1 and T C3 is T E or more is preferable. As the index the emission peak wavelength on the shortest wavelength side of the phosphorescence spectra of Compound 131 and Compound 133 is preferably both below the maximum emission peak wavelength of the exciplex. Alternatively, a tangent is drawn at the short wavelength side skirt of the fluorescence spectrum of the exciplex, and the energy of the wavelength of the extrapolated line is S and tangents are drawn at the short wavelength side skirts of the phosphorescence spectra of Compound 131 and Compound 133 respectively, and the energy of the wavelength of their extrapolated lines is T E for each compound. When T and T C1 of each compound are taken as T C 3, S E -T C1 ≤0.2 eV, and S E -T C3 ≤0.2 eV is preferable.

[0106] The triplet excitation energy generated in the light-emitting layer 130 can cause the guest material to emit light by passing through the energy transfer (Route A8) from the S1 level of the above Route A6 and the exciplex to the S1 level of the guest material. 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 element can be increased. Here, in the light-emitting element which is one aspect of the present invention, a guest material having a protecting group in the lumophore is used for Compound 132. By adopting such a configuration, as described above, the energy transfer by the Dexter mechanism represented by Route A9 can be suppressed, and the deactivation of the triplet excitation energy can be suppressed. Therefore, a fluorescent light-emitting element with high luminous efficiency can be obtained.

[0107] mechanism can be suppressed, and the deactivation of the triplet excitation energy can be suppressed. Therefore, a fluorescent light-emitting element with high luminous efficiency can be obtained. can be achieved. Therefore, a fluorescent light-emitting element with high luminous efficiency can be obtained.

[0108] ​​The above-mentioned processes of routes A6 to A8 are referred to as ExSET (Exci plex-Singlet Energy Transfer) or ExEF (Exc It is sometimes called iplex-Enhanced Fluorescence. In other words, the light-emitting layer 130 provides excitation energy from the exciplex to the fluorescent material.

[0109] <Emitting layer configuration example 3> In this configuration example, a phosphorescent material is used as the compound 133 of the light-emitting element using the above-mentioned ExEF. In other words, a phosphorescent material is used in one of the compounds forming an exciplex. The case where the above formula is used will be described.

[0110] 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 and triplet states is promoted. To form an exciplex that can transition from the nucleon to the singlet ground state (i.e., can exhibit phosphorescence), In this case, unlike ordinary exciplexes, the triplet excited energy of the exciplex can be generated. Energy level (T E ) is the energy donor level, so T E A compound in which the compound is a light-emitting material The singlet excited energy level of 132 (S G ) or more. Specifically, A tangent line is drawn at the short wavelength side of the emission spectrum of the exciplex using atoms, and the extrapolated line is The energy of the wavelength T E The energy of the wavelength of the absorption edge of the absorption spectrum of compound 132 is Ghee S G When this is done, T E ≧S G It is preferable that:

[0111] By correlating such energy levels, the triplet excitation energy of the generated exciplex - can transfer energy from the triplet excitation energy level (T E ) of the exciplex to the singlet excitation energy level (S ) of Compound 132. Note that since the S1 level (S G ) and the T1 level (T E ) of the exciplex are adjacent energy levels, it may be difficult to clearly distinguish fluorescence and phosphorescence in the emission spectrum E . In that case, it may be possible to distinguish fluorescence or phosphorescence by the emission lifetime .

[0112] Note that the phosphorescent material used in the above configuration preferably contains heavy atoms such as Ir, Pt, Os, Ru, Pd, etc. That is, energy transfer from the triplet excitation energy level of the exciplex to the singlet excitation energy level of the guest material should be an allowed transition. Energy transfer from the exciplex composed of the above-mentioned phosphorescent material or from the phosphorescent material to the guest material is preferable because 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, without going through the process of Route A7 in Fig. 4(C), the triplet excitation energy of the exciplex can be transferred to the S1 level (S ) of the guest material by the process of Route A8 . That 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 is the energy donor, and Compound 132 functions as the energy acceptor. Here G Route A8 is the emission process of the exciplex (from the S1 or T1 level of the exciplex to the basis set). In other words, the singlet excitation energy of the exciplex or The triplet excitation is converted to the emission of compound 131 and the emission of compound 132. The light-emitting element according to one embodiment of the present invention can emit light from Compound 131 and Compound 132. In this configuration example, the concentration of the compound 133 in the light-emitting layer 130 can be adjusted. By this, luminescence originating from compound 133 can also be obtained.

[0113] Compound 133 and the exciplex function as an energy donor and as a light-emitting material. In order to function as a stimulant, the concentration of compound 132 relative to the total amount of compound 131 and compound 133 must be It is preferable that the content of the compound is 0.01 wt% or more and 2 wt% or less. The excitation energy of compound 133 and the exciplex is calculated by the emission of compound 133, the emission of the exciplex and the excitation energy of compound 133. Since the light emitted from the object 132 can be efficiently converted, an efficient multi-color light-emitting device can be obtained. In addition, by adjusting the concentrations of Compound 131, Compound 132 and Compound 133, The light color can be adjusted.

[0114] In the light-emitting element according to one embodiment of the present invention, the compound 132 is a luminophore having a protecting group. By using this material, the dexterity represented by the route A9 can be obtained as described above. This suppresses the energy transfer by the - mechanism and suppresses the deactivation of triplet excitation energy. Therefore, a fluorescent light emitting device with high luminous efficiency can be obtained.

[0115] <Emitting layer configuration example 4> In this configuration example, the compound 133 of the light-emitting device using the above-mentioned ExEF has TADF properties. The case of using the material will be described with reference to FIG. 4(D).

[0116] Since compound 133 is a TADF material, compound 133 that has not formed an exciplex has a function of converting triplet excitation energy into singlet excitation energy by upconversion (Route A in FIG. 4(D) ). The singlet excitation energy possessed by compound 133 can quickly move to compound 132. (Route A in FIG. 4(D) 10 ). At this time, it is preferable that S 11 ≧ S . C3 ≧ S G is satisfied.

[0117] Similar to the configuration example of the previous light-emitting layer, in the light-emitting element of one aspect of the present invention, via Route A6 to Route A8 in FIG. 4(D), the triplet excitation energy moves to compound 132 which is a guest material , and there are paths for moving to compound 132 via Route A and Route A 10 in FIG. 4(D). Since there are a plurality of paths for the triplet excitation energy to move to the fluorescent material 11 , the light emission efficiency can be further improved. In Route A8, the exciplex functions as an energy donor, and compound 132 functions as an energy acceptor. In Route A , compound 133 functions as an energy donor, and compound 132 functions as an energy acceptor. Here, the process of Route A competes with the light emission process of compound 133 (transition from the S1 level of compound 133 to the ground state). That is, the singlet excitation energy possessed by compound 133 is converted into the light emission of compound 133 and the light emission of compound 132. 11 In, compound 133 functions as an energy donor, and compound 132 functions as an energy acceptor. Here, the process of Route A 11 competes with the light emission process of compound 133 (transition from the S1 level of compound 133 to the ground state). That is, the singlet excitation energy possessed by compound 133 is converted into the light emission of compound 133 and the light emission of compound 132. 133 to the ground state). That is, the singlet excitation energy possessed by compound 133 is converted into the light emission of compound 133 and the light emission of compound 132. is converted into the light emission of compound 133 and the light emission of compound 132. Therefore, the light-emitting element according to one embodiment of the present invention can emit light from Compound 133 and light from Compound 132. Also, as described above, the process of Route A8 competes with the process of light emission from the exciplex (transition from the S1 level of the exciplex to the ground state). That is, the singlet excitation energy of the exciplex is converted into light emission from the exciplex and light emission from Compound 132. Therefore, the light-emitting element according to one embodiment of the present invention can obtain light emission from the exciplex and light emission from Compound 132. In order for Compound 133 and the exciplex to function as an energy donor and also as a light-emitting material, the concentration of Compound 132 is preferably 0.01 wt% or more and 2 wt% or less with respect to the total amount of Compound 131 and Compound 133. With this configuration, the excitation energy of Compound 133 and the exciplex can be efficiently converted into light emission from Compound 133, light emission from the exciplex, and light emission from Compound 132, so that an efficient multi-color light-emitting element can be obtained. Also, by adjusting the concentrations of Compound 131, Compound 132, and Compound 133, the emission color can be adjusted. In this configuration example, the exciplex and Compound 133 are energy donors, and Compound 132 functions as an energy acceptor. <Configuration Example 5 of Light-Emitting Layer> FIG. 5(A) shows the case where four types of materials are used in the light-emitting layer 130. In FIG. 5(A), the light-emitting layer 130 includes Compound 131, Compound 132, Compound 133, and Compound 134. In one embodiment of the present invention, Compound 133 converts triplet excitation energy into light emission. For this reason, the light-emitting element of one aspect of the present invention can obtain light emission from the exciplex and light emission from Compound 132.

[0118] Compound 133 and the exciplex function as an energy donor and also as a light-emitting material. In order to do so, the concentration of Compound 132 is preferably 0.01 wt% or more and 2 wt% or less with respect to the total amount of Compound 131 and Compound 133. By adopting this configuration, the excitation energy of Compound 133 and the exciplex can be efficiently converted into light emission from Compound 133, light emission from the exciplex, and light emission from Compound 132. Therefore, an efficient multi-color light-emitting element can be obtained. Also, by adjusting the concentrations of Compound 131, Compound 132, and Compound 133, the emission color can be adjusted. That is, the singlet excitation energy of the exciplex is converted into light emission from the exciplex and light emission from Compound 132. Therefore, the light-emitting element of one aspect of the present invention can obtain light emission from the exciplex and light emission from Compound 132. Compound 133 and the exciplex function as an energy donor and also as a light-emitting material. In order for this to be the case, the concentration of Compound 132 is preferably 0.01 wt% or more and 2 wt% or less with respect to the total amount of Compound 131 and Compound 133. By adopting this configuration, the excitation energy of Compound 133 and the exciplex can be efficiently converted into light emission from Compound 133, light emission from the exciplex, and light emission from Compound 132. Therefore, an efficient multi-color light-emitting element can be obtained. Also, by adjusting the concentrations of Compound 131, Compound 132, and Compound 133, the emission color can be adjusted.

[0119] In this configuration example, the exciplex and Compound 133 are energy donors, and Compound 132 functions as an energy acceptor. <Configuration Example 5 of Light-Emitting Layer>

[0120] <Configuration Example 5 of Light-Emitting Layer> FIG. 5(A) shows the case where four types of materials are used in the light-emitting layer 130. In FIG. 5(A), the light-emitting layer 130 includes Compound 131, Compound 132, Compound 133, and Compound 134. In one embodiment of the present invention, Compound 133 converts triplet excitation energy into light emission. It has the function to be described. In this configuration example, the case where Compound 133 is a phosphorescent material will be described. . Compound 132 is a guest material that exhibits fluorescence emission. Also, Compound 131 is an organic compound that forms an exciplex with Compound 1 34.

[0121] In addition, the correlation of the energy levels of Compound 131, Compound 132, Compound 133, and Compound 134 in the light-emitting layer 130 is shown in FIG. 5(B). Note that the notations and symbols in FIG. 5(B) are as follows, and the other notations and symbols are the same as those shown in FIG. 4(C). and the symbols are as follows, and the other notations and symbols are the same as those shown in FIG. 4(C). ·Comp(134): Compound 134 ·S C4 : The S1 level of Compound 134 ·T C4 : The T1 level of Compound 134

[0122] In the light-emitting device according to one aspect of the present invention shown in this configuration example, Compound 131 and Compound 134 in the light-emitting layer 130 form an exciplex. The S1 level (S ) of the exciplex and the T1 level (T E ) of the exciplex are adjacent energy levels to each other (see Route A in FIG. 5(B) ). E ) (see Route A in FIG. 5(B)). 12

[0123] As described above, the exciplex generated by the above process loses excitation energy, and the two substances that formed the exciplex behave as the original separate substances again.

[0124] The excitation energy levels (S E and T E ) of the exciplex are lower than the S1 levels (S ) of the substances (Compound 131 and Compound 134) that form the exciplex. C1 and S C4 ) of each substance (Compound 131 and Compound 134) that forms the exciplex, so It is possible to form an excited state with lower excitation energy. This allows the luminescent element The driving voltage of the element 150 can be reduced.

[0125] Here, compound 133 is a phosphorescent material, and intersystem crossing between the singlet and triplet states is Therefore, the singlet excitation energy and triplet excitation energy of the exciplex are Both glycine and glycine are rapidly transferred to compound 133 (Route A 13 ). At this time, T E ≧T C3 In addition, it is preferable that the triplet excitation energy of compound 133 is efficiently converted. The singlet excitation energy of compound 132 can be converted to the 14 ), where , As shown in Figure 5(B), T E ≧T C3 ≧S G Then, the excitation energy of compound 133 is This allows efficient transfer of the singlet excitation energy to the guest material, compound 132. Specifically, a tangent line is drawn at the short wavelength side of the phosphorescence spectrum of compound 133. Then, the energy of the wavelength of the extrapolated line is T C3 The absorption spectrum of compound 132 is The energy of the edge wavelength is S G When this is done, T C3 ≧S G It is preferable that the compound is The peak wavelength of the emission spectrum of compound 133 is the longest wavelength of the absorption spectrum of compound 132. It is preferable that the absorption band overlaps with the long side absorption band. Route A 14 In the study, compound 133 was found to be an energy donor. The ner, compound 132, functions as an energy acceptor. Here, Route A 14 of This process competes with the emission process of compound 133 (the transition from the T1 level of compound 133 to the ground state). They match. That is, the triplet excitation energy of Compound 133 is converted into the luminescence of Compound 133 and the luminescence of Compound 132. Therefore, the light-emitting element of one embodiment of the present invention can obtain the luminescence from Compound 1 33 and the luminescence from Compound 132.

[0126] At this time, the combination of Compound 131 and Compound 134 may be any combination that can form an exciplex, but it is more preferable that one is a compound having hole-transporting properties and the other is a compound having electron-transporting properties.

[0127] In order for Compound 133 to function as an energy donor and also as a light-emitting material, the concentration of Compound 132 is preferably 0.01 wt% or more and 2 wt% or less with respect to the total amount of Compound 131, Compound 133, and Compound 134. With this configuration, the excitation energy of Compound 133 can be efficiently converted into the luminescence of Compound 133 and the luminescence of Compound 132, so that an efficient multi-color light-emitting element can be obtained. Also, by adjusting the concentrations of Compound 131, Compound 1 32, Compound 133, and Compound 134, the emission color can be adjusted.

[0128] In addition, as a combination of materials that can 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.

[0129] Also, the correlation between the energy levels of Compound 131 and Compound 134 is not limited to Fig. 5(B). That is, the singlet excitation energy level (S ) of Compound 131 is C1 ) of Compound 13 It may be higher or lower than the singlet excitation energy level (S C4 ) of 4. Also, for Compound 13 1, the triplet excitation energy level (T C1 ) may be higher or lower than the triplet excitation energy level (T C4 ) of Compound 134.

[0130] Further, in the light-emitting device according to one aspect of the present invention, it is preferable that Compound 131 has a π-electron deficient skeleton . With this configuration, the LUMO level of Compound 131 becomes lower, which is suitable for the formation of an exciplex.

[0131] Also, in the light-emitting device according to one aspect of the present invention, it is preferable that Compound 131 has a π-electron rich skeleton . With this configuration, the HOMO level of Compound 131 becomes higher, which is suitable for the formation of an exciplex.

[0132] Here, in the light-emitting device which is one aspect of the present invention, a guest material in which the light-emitting group of Compound 132 has a protecting group is used. With this configuration, as described above, the energy transfer by the Dexter mechanism represented by Route A 15 can be suppressed, and the deactivation of the triplet excitation energy can be suppressed. Therefore, a fluorescent light-emitting device with high luminous efficiency can be obtained.

[0133] In addition, the processes of Route A 12 and A 13 shown above may be referred to as ExTET (E xciplex - Triplet Energy Transfer) in this specification and the like. In other words, there is an excitation energy supply from the exciplex to Compound 133 in the light-emitting layer 130. Therefore, this configuration example can be said to be a configuration in which a fluorescent material having a protecting group is mixed in a light-emitting layer capable of utilizing ExTET. ​

[0134] <Example 6 of the structure of the light-emitting layer> In this exemplary configuration, the case where a material having TADF properties is used for Compound 134 described in Exemplary Configuration 5 of the light-emitting layer described above will be described. will be described.

[0135] FIG. 5(C) shows the case where four materials are used in the light-emitting layer 130. In FIG. 5(C), the light-emitting layer 130 includes Compound 131, Compound 132, Compound 133, and Compound 134. In one aspect of the present invention, Compound 133 has a function of converting triplet excitation energy into light emission. Compound 132 is a guest material that exhibits fluorescence emission. Also, Compound 1 31 is an organic compound that forms an exciplex with Compound 134.

[0136] Here, since Compound 134 is a TADF material, Compound 13 4 that does not form an exciplex has a function of converting triplet excitation energy into singlet excitation energy by upconversion (Route A in FIG. 5(C) ). 16 ) The singlet excitation energy possessed by Compound 134 can quickly move to Compound 132. (Route A1 in FIG. 5(C) 7). At this time, it is preferable that S ≧S C4 ≧S G . Here, the process of Route A 17 competes with the light emission process of Compound 134 (transition from the S1 level of Compound 134 to the ground state). That is, the singlet excitation energy possessed by Compound 134 is converted into the light emission of Compound 134 and the light emission of Compound 13 2. Therefore, the light-emitting element of one aspect of the present invention can obtain light emission from Compound 134 and light emission from Compound 132. Also, as shown in Exemplary Configuration 5 of the light-emitting layer, as described above, The triplet excitation energy of the sea urchin compound 133 can be efficiently converted into the singlet excitation energy of the compound 132 (Route A 14 ), and luminescence from the compound 133 can also be obtained .

[0137] For the compound 133 and the compound 134 to function as an energy donor and also as a luminescent material, relative to the total amount of the compound 131, the compound 133, and the compound 134 it is preferable that the concentration of the compound 132 is 0.01 wt% or more and 2 wt% or less. With this configuration the excitation energy of the compound 133 and the compound 134 can be efficiently converted into the luminescence of the compound 133, the luminescence of the compound 134, and the luminescence of the compound 132, so that an efficient multicolor light-emitting device can be obtained. Also, by adjusting the concentrations of the compound 131, the compound 132, the compound 133, and the compound 134, the emission color can be adjusted. Specifically, a tangent is drawn at the short-wavelength side skirt of the fluorescence spectrum of the compound 134, and the energy of the wavelength of the extrapolated line is defined as S , and when the energy of the wavelength at the absorption edge of the absorption spectrum of the compound 132 is defined as S , it is preferable that S

[0138] ≧S . Also, the emission spectrum of the compound 134 preferably overlaps with the absorption band on the longest wavelength side of the absorption spectrum of the compound 132. C4 . G C4 G . Similar to the configuration example of the previous light-emitting layer, in the light-emitting device of one aspect of the present invention, via the route A in FIG. 5(C) or the route A

[0139] to the route A in FIG. 5(C), the path through which the triplet excitation energy moves to the compound 132, which is the guest material 12 to 14 the route A in FIG. 5(C), the triplet excitation energy moves to the compound 132, which is the guest material​​​16 and route A 17 to move to Compound 132 via There is a path for the triplet excitation energy to move to the fluorescent material. Since there are multiple paths for the triplet excitation energy to move to the fluorescent material, the luminous efficiency can be further increased. In route A 14 Compound 133 functions as an energy donor, and Compound 132 functions as an energy acceptor. Also, in route A 17 Compound 134 functions as an energy donor, and Compound 132 functions as an energy ac ceptor.

[0140] As described above, the light-emitting element according to one embodiment of the present invention can obtain multi-color light emission by the energy transfer path. Also, by adjusting the concentrations of Compound 132, Compound 133, and Compound 134 in the light-emitting layer 130, the emission color can be adjusted. That is, by adjusting the concentrations of Compound 132, Compound 133, and Compound 134 in the light-emitting layer 1 30, the emission intensity from Compound 132, the emission intensity from Compound 133, and the emission intensity from the exciplex can be adjusted .

[0141] <Configuration Example 7 of Light-Emitting Layer> FIG. 6(B) is an example of the correlation of energy levels in the light-emitting layer 130 of the light-emitting element 150 according to one embodiment of the present invention. The light-emitting layer 130 shown in FIG. 6(A) has Compound 131, Compound 132 , and further Compound 133. In one embodiment of the present invention, Compound 132 is a fluorescent material having a protecting group. Also, Compound 133 has a function of converting triplet excitation energy into light emission. In this configuration example, the case where Compound 133 is a phosphorescent material will be described .

[0142] ​​Note that the notations and reference numerals in FIG. 6(B) and FIG. 6(C) 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

[0143] In the light-emitting element according to one embodiment of the present invention, in Compound 131 included in the light-emitting layer 130, recombination of carriers mainly occurs, thereby generating singlet excitons and triplet excitons. Here, since Compound 133 is a phosphorescent material, C3 T C1 select a material having the relationship of ≤ T T C3 so that both the singlet and triplet excitation energies generated in Compound 131 can move to the 18 T level of Compound 133 (Route A in FIG. 6(B)

[0144] Note that the phosphorescent material used in the above configuration preferably contains heavy atoms such as Ir, Pt, Os, Ru, and Pd. When the phosphorescent material is used as Compound 133, since 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, it is preferable. Therefore, the triplet excitation energy of Compound 133 is transferred to the S1 level (S of the guest material by the process of Route A 19 of the guest material through the process of Route A.​G ) Move to It can be moved. Route A 19 In, compound 133 is an energy donor, and the compound Compound 132 functions as an energy acceptor. In this case, T C3 ≥ S G If so, The excitation energy of compound 133 efficiently transfers to the singlet excited state of compound 132, which is the guest material. Here, the process of Route A 19 competes with the emission process of compound 133 ( The transition from the T1 level of compound 133 to the ground state). That is, the triplet excitation energy possessed by compound 133 is converted into the emission of compound 133 and the emission of compound 132. Therefore, the light-emitting device of one embodiment of the present invention can obtain the emission from compound 133 and the emission from compound 132.

[0145] In order for compound 133 to function as an energy donor and also as a light-emitting material, the concentration of compound 132 is preferably 0.01 wt% or more and 2 wt% or less with respect to the total amount of compound 131 and compound 133. With this configuration, the excitation energy of compound 133 can be efficiently converted into the emission of compound 133 and the emission of compound 132, so that an efficient multi-color light-emitting device can be obtained. Also, by adjusting the concentrations of compound 131, compound 132, and compound 133, the emission color can be adjusted.

[0146] Specifically, a tangent is drawn at the short-wavelength side skirt of the phosphorescence spectrum of compound 133, and the energy of the wavelength of the tangent line is defined as T And the energy of the wavelength at the absorption edge of the absorption spectrum of compound 132 is defined as S C3 G When T C3 ≥ S​​​​​​​​​G is preferable. Further, Compound 133 The emission spectrum of preferably overlaps with the absorption band on the longest wavelength side of the absorption spectrum of Compound 132 is preferable.

[0147] Here, in the light-emitting element which is one aspect of the present invention, a guest material having a protecting group in the light-emitting group is used for Compound 132 By adopting this configuration, as described above, the Dexter mechanism represented by Route A 20 The dexter represented by The energy transfer by the mechanism can be suppressed, and the deactivation of triplet excitons can be suppressed As a result, a fluorescent light-emitting element with high luminous efficiency can be obtained.

[0148] <Configuration Example 8 of Light-Emitting Layer> FIG. 6(C) is an example of the correlation of energy levels in the light-emitting layer 130 of the light-emitting element 150 according to one aspect of the present invention The light-emitting layer 130 shown in FIG. 6(C) includes Compound 131, Compound 132 and further Compound 133. In one aspect of the present invention, Compound 132 is a fluorescent material having a protecting group group. Further, Compound 133 has a function of converting triplet excitons into light emission In this configuration example, the case where Compound 133 is a compound having TADF properties will be described will be described.

[0149] The notations and symbols in FIG. 6(C) are as follows, and other notations and symbols are the same as those shown in FIG. 6( B). ·S C3 : S1 level of Compound 133

[0150] In the light-emitting element according to one aspect of the present invention, singlet excitons and triplet excitons are generated by the recombination of carriers mainly occurring in Compound 131 included in the light-emitting layer 130 Here, S Here, S C3 ≦SC1 and T C3 ≤ T C1 By selecting a material having such a relationship, singlet excitation energy and triplet excitation energy generated at 31 can both be transferred to the S of Compound 133 31 and the T C 3 and T C3 levels (Route A in Fig. 6(C) 21 ). Note that some carriers can recombine in Compound 133 .

[0151] Here, since Compound 133 is a TADF material, it has a function of converting triplet excitation energy into singlet excitation energy by upconversion (Route A in Fig. 6(C) ). Also, the singlet excitation energy possessed by Compound 133 can quickly move to Compound 132 (Route A in Fig. 6(C) 22 ). At this time, it is preferable that S ≥ S 23 C3 . Here, the process of Route A G 23 competes with the emission process of Compound 133 (transition from the S 1 level of Compound 133 to the ground state). That is, the singlet excitation energy possessed by Compound 133 is converted into the emission of Compound 133 and the emission of Compound 132. Therefore, the light-emitting device according to one aspect of the present invention can obtain the emission from Compound 133 and the emission from Compound 132 23 . That is, the singlet excitation energy possessed by Compound 133 is converted into the emission of Compound 133 and the emission of Compound 132. Therefore, the light-emitting device according to one aspect of the present invention can obtain the emission from Compound 133 and the emission from Compound 132 . That is, the singlet excitation energy possessed by Compound 133 is converted into the emission of Compound 133 and the emission of Compound 132. Therefore, the light-emitting device according to one aspect of the present invention can obtain the emission from Compound 133 and the emission from Compound 132 . That is, the singlet excitation energy possessed by Compound 133 is converted into the emission of Compound 133 and the emission of Compound 132. Therefore, the light-emitting device according to one aspect of the present invention can obtain the emission from Compound 133 and the emission from Compound 132 . That is, the singlet excitation energy possessed by Compound 133 is converted into the emission of Compound 133 and the emission of Compound 132. Therefore, the light-emitting device according to one aspect of the present invention can obtain the emission from Compound 133 and the emission from Compound 132 .

[0152] In order for Compound 133 to function as an energy donor and also as a light-emitting material, it is preferable that the concentration of Compound 132 is 0.01 wt% or more and 2 wt% or less with respect to the total amount of Compound 131 and Compound 133. By adopting such a configuration, the excitation energy of Compound 133 can be efficiently converted into the emission of Compound 133 and the emission of Compound 132, so that the efficiency . By adopting such a configuration, the excitation energy of Compound 133 can be efficiently converted into the emission of Compound 133 and the emission of Compound 132, so that the efficiency . By adopting such a configuration, the excitation energy of Compound 133 can be efficiently converted into the emission of Compound 133 and the emission of Compound 132, so that the efficiency . By adopting such a configuration, the excitation energy of Compound 133 can be efficiently converted into the emission of Compound 133 and the emission of Compound 132, so that the efficiency A highly efficient multi-color light-emitting device can be obtained. Also, by adjusting the concentrations of Compound 131, Compound 132, and Compound 133, the emission color can be adjusted.

[0153] Specifically, a tangent is drawn at the short-wavelength side skirt of the fluorescence spectrum of Compound 133, and the energy of the wavelength of the tangent line outside is defined as S C3 , and the energy of the wavelength at the absorption edge of the absorption spectrum of Compound 132 is defined as S G . When S C3 ≥ S G , it is preferable. Also, the emission spectrum of Compound 133 preferably overlaps with the absorption band on the longest wavelength side of the absorption spectrum of Compound 132. Through the process of Route A to Route A , the triplet 21 to Route A 23 excitation energy in the light-emitting layer 130 can be converted into the fluorescence emission of Compound 132. In Route A , Compound 133 functions as an energy donor and Compound 132 functions as an energy acceptor. 23 In , Compound 133 functions as an energy donor and Compound 132 functions as an energy acceptor.

[0154] Here, in the light-emitting device which is one aspect of the present invention, a guest material having a protecting group on the lumophore is used for Compound 132. By adopting such a configuration, as described above, the energy transfer by the Dexter mechanism represented by Route A can be suppressed, and the deactivation of the triplet excitation energy can be suppressed. Therefore, a fluorescent light-emitting device with high luminous efficiency can be obtained. 24 represented by Route A can suppress the energy transfer by the Dexter mechanism and suppress the deactivation of the triplet excitation energy. Therefore, a fluorescent light-emitting device with high luminous efficiency can be obtained.

[0155] <Energy Transfer Mechanism> Here, the Förster mechanism and the Dexter mechanism will be described. Here, regarding the donation of excitation energy from the first material in the excited state to the second material in the ground state, the first The intermolecular energy transfer process between the first material and the second material will be described. In either case where an exciplex is formed, the situation is the same.

[0156] ≪Förster mechanism≫ In the Förster mechanism, energy transfer does not require direct intermolecular contact. Energy transfer occurs through the resonance phenomenon of the dipole vibrations of the first material and the second material. Through the resonance phenomenon of dipole vibrations, the first material transfers energy to the second material, causing the first material in the excited state to return to the ground state and the second material in the ground state to become excited. Note that the rate constant k of the Förster mechanism is shown in Equation (1). of the Förster mechanism is shown in Equation (1). h*→g is shown in Equation (1).

[0157]

Equation

[0158] In Equation (1), ν represents the frequency, f’ h (ν) represents the normalized emission spectrum of the first material (fluorescence spectrum when discussing energy transfer from the singlet excited state, phosphorescence spectrum when discussing energy transfer from the triplet excited state), ε g ( ν) represents the molar extinction 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 lifetime of the excited state (fluorescence lifetime or phosphorescence lifetime), c represents the speed of light, φ represents the emission quantum yield (fluorescence quantum yield when discussing energy transfer from the singlet excited state, phosphorescence quantum yield when discussing energy transfer from the triplet excited state), K represents the orientation factor between the first material and the second material 2 is the orientation factor between the first material and the second material It is a coefficient (from 0 to 4) representing the orientation of the transition dipole moment. In the case of random orientation the situation is K 2 = 2 / 3.

[0159] ≪Dexter mechanism≫ In the Dexter mechanism, the first material and the second material approach the contact effective distance where orbital overlap occurs, and energy transfer occurs through the exchange of electrons between the excited state electrons of the first material and the electrons of the second material in the ground state. The rate constant k of the Dexter mechanism is shown in Equation (2). h*→g is shown in Equation (2).

[0160]

Equation

[0161] In Equation (2), h is Planck's constant, K is a constant with the dimension of energy, ν represents the frequency, f’ h (ν) represents the normalized emission spectrum of the first material (fluorescence spectrum when discussing energy transfer from the singlet excited state, phosphorescence spectrum when discussing energy transfer from the triplet excited state), ε’ (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 g material and the second material. Here, the energy transfer efficiency φ from the first material to the second material is expressed by Equation (3). k

[0162] Here, the energy transfer efficiency φ ET from the first material to the second material is expressed by Equation (3). k is the rate constant of the emission process of the first material (fluorescence when discussing energy transfer from the singlet excited state, phosphorescence when discussing energy transfer from the triplet excited state), r and k is the rate constant of the emission process of the first material (fluorescence when discussing energy transfer from the singlet excited state, phosphorescence when discussing energy transfer from the triplet excited state), and k n ​​represents the rate constant of the non-emission process (thermal deactivation and intersystem crossing) of the second material, and τ represents the measured lifetime of the excited state of the first material.

[0163] [Number]

[0164] From Equation (3), it can be seen that to increase the energy transfer efficiency φ ET , the rate constant k of energy transfer should be increased, and the other competing rate constant k h*→g +k r (=1 / τ) should be relatively n small.

[0165] ≪Concepts for enhancing energy transfer≫ First, consider energy transfer by the Förster mechanism. τ can be eliminated by substituting Equation (1) into Equation (3). Therefore, in the case of the Förster mechanism, the energy transfer efficiency φ does not depend on the lifetime τ of the excited state of the first material. Also, it can be said that the higher the luminescence quantum yield φ, the better the energy transfer efficiency φ . ET In addition, it is preferable that the overlap between 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) is large. Furthermore, ET 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 that appears on the longest wavelength side of the second material. Note that since the direct transition from the singlet ground state to the triplet excited state in the second material is forbidden,

[0166] the molar absorption coefficient related to the triplet excited state in the second material can be ignored. ​Therefore, the energy transfer process from the excited state of the first material to 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. The energy transfer rate by the Förster mechanism is inversely proportional to the sixth power of the intermolecular distance R between the first material and the second material according to Equation (1). Also, as described above, when R is 1 nm or less, energy transfer by the Dexter mechanism becomes dominant. Therefore, in order to suppress energy transfer by the Dexter mechanism and increase the energy transfer rate by the Förster mechanism, the intermolecular distance is preferably 1 nm or more and 10 nm or less. Thus, since the above-described protecting group is required not to be too bulky, the number of carbon atoms constituting the protecting group is preferably 3 or more and 10 or less.

[0167] Also, the energy transfer rate by the Förster mechanism is inversely proportional to the sixth power of the intermolecular distance R between the first material and the second material according to Equation (1). Also, as described above, when R is 1 nm or less, energy transfer by the Dexter mechanism becomes dominant. Therefore, in order to suppress energy transfer by the Dexter mechanism and increase the energy transfer rate by the Förster mechanism, the intermolecular distance is preferably 1 nm or more and 10 nm or less. Thus, since the above-described protecting group is required not to be too bulky, the number of carbon atoms constituting the protecting group is preferably 3 or more and 10 or less. The energy transfer rate by the Förster mechanism is inversely proportional to the sixth power of the intermolecular distance R between the first material and the second material according to Equation (1). Also, as described above, when R is 1 nm or less, energy transfer by the Dexter mechanism becomes dominant. Therefore, in order to suppress energy transfer by the Dexter mechanism and increase the energy transfer rate by the Förster mechanism, the intermolecular distance is preferably 1 nm or more and 10 nm or less. Thus, since the above-described protecting group is required not to be too bulky, the number of carbon atoms constituting the protecting group is preferably 3 or more and 10 or less. The energy transfer rate by the Förster mechanism is inversely proportional to the sixth power of the intermolecular distance R between the first material and the second material according to Equation (1). Also, as described above, when R is 1 nm or less, energy transfer by the Dexter mechanism becomes dominant. Therefore, in order to suppress energy transfer by the Dexter mechanism and increase the energy transfer rate by the Förster mechanism, the intermolecular distance is preferably 1 nm or more and 10 nm or less. Thus, since the above-described protecting group is required not to be too bulky, the number of carbon atoms constituting the protecting group is preferably 3 or more and 10 or less. The energy transfer rate by the Förster mechanism is inversely proportional to the sixth power of the intermolecular distance R between the first material and the second material according to Equation (1). Also, as described above, when R is 1 nm or less, energy transfer by the Dexter mechanism becomes dominant. Therefore, in order to suppress energy transfer by the Dexter mechanism and increase the energy transfer rate by the Förster mechanism, the intermolecular distance is preferably 1 nm or more and 10 nm or less. Thus, since the above-described protecting group is required not to be too bulky, the number of carbon atoms constituting the protecting group is preferably 3 or more and 10 or less. The energy transfer rate by the Förster mechanism is inversely proportional to the sixth power of the intermolecular distance R between the first material and the second material according to Equation (1). Also, as described above, when R is 1 nm or less, energy transfer by the Dexter mechanism becomes dominant. Therefore, in order to suppress energy transfer by the Dexter mechanism and increase the energy transfer rate by the Förster mechanism, the intermolecular distance is preferably 1 nm or more and 10 nm or less. Thus, since the above-described protecting group is required not to be too bulky, the number of carbon atoms constituting the protecting group is preferably 3 or more and 10 or less. The energy transfer rate by the Förster mechanism is inversely proportional to the sixth power of the intermolecular distance R between the first material and the second material according to Equation (1). Also, as described above, when R is 1 nm or less, energy transfer by the Dexter mechanism becomes dominant. Therefore, in order to suppress energy transfer by the Dexter mechanism and increase the energy transfer rate by the Förster mechanism, the intermolecular distance is preferably 1 nm or more and 10 nm or less. Thus, since the above-described protecting group is required not to be too bulky, the number of carbon atoms constituting the protecting group is preferably 3 or more and 10 or less.

[0168] Next, consider energy transfer by the Dexter mechanism. According to Equation (2), it can be seen that in order to increase the rate constant k, it is better that the overlap between the emission spectrum of the first material (fluorescence spectrum when discussing energy transfer from the singlet excited state, phosphorescence spectrum when discussing energy transfer from the 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) is larger. Therefore, optimization of the energy transfer efficiency is achieved by the overlap between the emission spectrum of the first material and the absorption band that appears on the longest wavelength side of the second material. k h*→g Next, consider energy transfer by the Dexter mechanism. According to Equation (2), it can be seen that in order to increase the rate constant k, it is better that the overlap between the emission spectrum of the first material (fluorescence spectrum when discussing energy transfer from the singlet excited state, phosphorescence spectrum when discussing energy transfer from the 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) is larger. Therefore, optimization of the energy transfer efficiency is achieved by the overlap between the emission spectrum of the first material and the absorption band that appears on the longest wavelength side of the second material. Next, consider energy transfer by the Dexter mechanism. According to Equation (2), it can be seen that in order to increase the rate constant k, it is better that the overlap between the emission spectrum of the first material (fluorescence spectrum when discussing energy transfer from the singlet excited state, phosphorescence spectrum when discussing energy transfer from the 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) is larger. Therefore, optimization of the energy transfer efficiency is achieved by the overlap between the emission spectrum of the first material and the absorption band that appears on the longest wavelength side of the second material. Next, consider energy transfer by the Dexter mechanism. According to Equation (2), it can be seen that in order to increase the rate constant k, it is better that the overlap between the emission spectrum of the first material (fluorescence spectrum when discussing energy transfer from the singlet excited state, phosphorescence spectrum when discussing energy transfer from the 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) is larger. Therefore, optimization of the energy transfer efficiency is achieved by the overlap between the emission spectrum of the first material and the absorption band that appears on the longest wavelength side of the second material. Next, consider energy transfer by the Dexter mechanism. According to Equation (2), it can be seen that in order to increase the rate constant k, it is better that the overlap between the emission spectrum of the first material (fluorescence spectrum when discussing energy transfer from the singlet excited state, phosphorescence spectrum when discussing energy transfer from the 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) is larger. Therefore, optimization of the energy transfer efficiency is achieved by the overlap between the emission spectrum of the first material and the absorption band that appears on the longest wavelength side of the second material. Next, consider energy transfer by the Dexter mechanism. According to Equation (2), it can be seen that in order to increase the rate constant k, it is better that the overlap between the emission spectrum of the first material (fluorescence spectrum when discussing energy transfer from the singlet excited state, phosphorescence spectrum when discussing energy transfer from the 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) is larger. Therefore, optimization of the energy transfer efficiency is achieved by the overlap between the emission spectrum of the first material and the absorption band that appears on the longest wavelength side of the second material. Next, consider energy transfer by the Dexter mechanism. According to Equation (2), it can be seen that in order to increase the rate constant k, it is better that the overlap between the emission spectrum of the first material (fluorescence spectrum when discussing energy transfer from the singlet excited state, phosphorescence spectrum when discussing energy transfer from the 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) is larger. Therefore, optimization of the energy transfer efficiency is achieved by the overlap between the emission spectrum of the first material and the absorption band that appears on the longest wavelength side of the second material.

[0169] Also, when Equation (2) is substituted into Equation (3), it can be seen that the energy transfer efficiency φ in the Dexter mechanism depends on τ. The Dexter mechanism is an energy φ ET transfer based on electron exchange.​ Since it is an energy transfer process, from the singlet excited state of the first material to the singlet excited state of the second material Similar to the energy transfer to the singlet excited state of the second material, energy transfer from the triplet excited state of the first material to the triplet excited state of the second material also occurs.

[0170] In the light-emitting element of one aspect of the present invention, since the second material is a fluorescent material, it is preferable that the energy transfer efficiency to the triplet excited state of the second material is low. That is, it is preferable that the energy transfer efficiency based on the Dexter mechanism from the first material to the second material is low and the energy transfer efficiency based on the Förster mechanism from the first material to the second material is high. Also, as already described, the energy transfer efficiency in the Förster mechanism does not depend on the lifetime τ of the excited state of the first material. On the other hand, the energy transfer efficiency in the Dexter mechanism depends on the excitation lifetime τ of the first material, and in order to lower the energy transfer efficiency in the Dexter mechanism, it is preferable that the excitation lifetime τ of the first material is short.

[0171] Therefore, one aspect of the present invention uses an exciplex, a phosphorescent material, or a TADF material 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 emission quantum yield of the energy donor, a first material that can convert the energy of the triplet excited state into light emission, such as a phosphorescent material, an exciplex, or a TADF material, can transfer its excitation energy to the second material by the Förster mechanism. On the other hand, due to the configuration of one aspect of the present invention, the first material (exciplex or

[0172] Thus, one aspect of the present invention uses an exciplex, a phosphorescent material, or a TADF material as the first material. These materials have the function of converting triplet excitation energy into light emission. Since the energy transfer efficiency of the Förster mechanism depends on the emission quantum yield of the energy donor, a first material such as a phosphorescent material, an exciplex, or a TADF material that can convert the energy of the triplet excited state into light emission can transfer its excitation energy to the second material by the Förster mechanism. On the other hand, due to the configuration of one aspect of the present invention, the first material (exciplex or ​​​​​​​​​The reverse intersystem crossing from the triplet excited state of the TADF material to the singlet excited state is promoted, and the The triplet excited state lifetime τ of the first material can be shortened. The conversion from the triplet excited state of an exciplex (using a photoluminescent or phosphorescent material) to the singlet ground state The transition can be promoted, and the excited lifetime τ of the triplet excited state of the first material can be shortened. As a result, the triplet excited state of the first material is converted to the triplet excited state of the fluorescent material (second material). This can reduce the efficiency of energy transfer in the Dexter mechanism to

[0173] In addition, in the light-emitting element of one embodiment of the present invention, as described above, the second material has a protecting group. A fluorescent material is used. Therefore, the intermolecular distance between the first material and the second material is increased. Therefore, in the light-emitting element of one embodiment of the present invention, the first material has triplet excitation energy The first material is a fluorescent material having a protecting group. This can reduce the efficiency of energy transfer via the Dexter mechanism. As a result, non-radiative deactivation of triplet excitation energy in the light-emitting layer 130 can be suppressed. In this way, a light-emitting element with high luminous efficiency can be provided.

[0174] <Material> Next, components of a light-emitting element according to one embodiment of the present invention will be described in detail below.

[0175] <Light-emitting layer> The materials that can be used for the light-emitting layer 130 of the present invention are described below. The light-emitting layer of the light-emitting element of one embodiment includes an emitter having a function of converting triplet excitation energy into light emission. The triplet excitation is achieved by using an energy acceptor and an energy donor with a protecting group on the luminophore. Examples of materials having a function of converting starting energy into light include TADF materials and phosphorescent materials. These include.

[0176] Examples of the lumophore included in compound 132 that functions as an energy acceptor include, for example, a flu renanthrene skeleton, a stilbene skeleton, an acridone skeleton, a phenoxazine skeleton, a phenothia zine skeleton, and the like. In particular, fluorescent materials having a naphthalene skeleton, an anthracene skeleton, a fluorene skeleton, a chry sene skeleton, a triphenylene skeleton, a tetracene skeleton, a pyrene skeleton, a perylene skeleton, a coumar in skeleton, a quinacridone skeleton, and a naphthobisbenzofuran skeleton are preferable because of their high fluorescence quantum yield.

[0177] In addition, as the protecting group, an alkyl group having 1 to 10 carbon atoms, a cyclo alkyl group having 3 to 10 carbon atoms, a branched alkyl group having 3 to 10 carbon atoms, or a tri alkylsilyl group having 3 to 12 carbon atoms is preferable.

[0178] Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group, a pent yl group, and a hexyl group. However, a branched alkyl group having 3 to 10 carbon atoms, which will be described later, is particularly preferable. Note that the alkyl group is not limited to these.

[0179] Examples of the cycloalkyl group having 3 to 10 carbon atoms include a cyclopropyl group, a cyclobutyl group , a cyclohexyl group, a norbornyl group, an adamantyl group, and the like. The cycloalkyl group is not limited to these. When the cycloalkyl group has a substituent, examples of the substituent include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, and a hexyl group, such as those having 1 to An alkyl group having 7 carbon atoms, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, an 8,9, 10-trinorbornanyl group, and other cycloalkyl groups having 5 to 7 carbon atoms, a phenyl group, a naphthyl group, an aryl group having 6 to 12 carbon atoms such as a biphenyl group, and the like can be mentioned.

[0180] Examples of the branched alkyl group having 3 to 10 carbon atoms include an isopropyl group, a sec-butyl group , an isobutyl group, a tert-butyl group, an isopentyl group, a sec-pentyl group, a tert -pentyl group, a neopentyl group, an isohexyl group, a 3-methylpentyl group, a 2-methylpe ntyl group, a 2-ethylbutyl group, a 1,2-dimethylbutyl group, a 2,3-dimethylbutyl group and the like. The branched alkyl group is not limited to these.

[0181] Examples of the trialkylsilyl group having 3 to 12 carbon atoms include a trimethylsilyl group, a trieth ylsilyl group, a tert-butyldimethylsilyl group and the like. The trialkylsilyl group is not limited to these.

[0182] Further, as the molecular structure of the energy acceptor, a structure in which a lumophore is bonded to two or more diarylamino groups, and each of the aryl groups of the diarylamino group has at least one protecting group is preferable. It is more preferable that at least two protecting groups are bonded to each of the aryl groups. When the guest material is used in the light-emitting layer, the larger the number of protecting groups, the greater the effect of suppressing energy transfer by the Dexter mechanism. Incidentally, in order to suppress an increase in molecular weight and maintain sublimability, the diarylamino group is preferably a diphenylamino group.

[0183] ​​​In addition, by bonding two or more amino groups to the lumophore, a fluorescent material with high quantum yield can be obtained while adjusting the emission color. Also, it is preferable that the amino group is bonded to a symmetric position with respect to the lumophore. By adopting such a configuration, a fluorescent material with high quantum yield can be obtained. Also, instead of directly introducing a protecting group into the lumophore, the protecting group may be introduced via the aryl group of the diarylamine. With this configuration, since the protecting group can be arranged to cover the lumophore, it is preferable because the distance between the host material and the lumophore can be increased in any direction. Also, when the protecting group is not directly bonded to the lumophore, it is preferable to introduce four or more protecting groups for one lumophore. In addition, as shown in FIG. 3, it is preferable that at least one of the atoms constituting the plurality of protecting groups is located directly above one surface of the lumophore, that is, the condensed aromatic ring or the condensed heteroaromatic ring, and at least one of the atoms constituting the plurality of protecting groups is located directly above the other surface of the condensed aromatic ring or the condensed heteroaromatic ring. Specific methods thereof include the following configurations. That is, the condensed aromatic ring or the condensed heteroaromatic ring, which is the lumophore, is bonded to two or more diphenylamino groups, and the phenyl groups in the two or more diphenylamino groups each independently have protecting groups at the 3-position and the 5-position. By adopting such a configuration, as shown in FIG. 3, a three-dimensional arrangement is achieved such that the protecting group at the 3-position or the 5-position on the phenyl group comes directly above the condensed aromatic ring or the condensed heteroaromatic ring, which is the lumophore.

[0184] In addition, instead of directly introducing a protecting group into the lumophore, the protecting group may be introduced via the aryl group of the diarylamine. With this configuration, since the protecting group can be arranged to cover the lumophore, the distance between the host material and the lumophore can be increased in any direction, which is preferable. Also, when the protecting group is not directly bonded to the lumophore, it is preferable to introduce four or more protecting groups for one lumophore. In addition, as shown in FIG. 3, at least one of the atoms constituting the plurality of protecting groups is located directly above one surface of the lumophore,

[0185] that is, the condensed aromatic ring or the condensed heteroaromatic ring, and at least one of the atoms constituting the plurality of protecting groups is located directly above the other surface of the condensed aromatic ring or the condensed heteroaromatic ring. That is, the condensed aromatic ring or the condensed heteroaromatic ring, which is the lumophore, is bonded to two or more diphenylamino groups, and the phenyl groups in the two or more diphenylamino groups each independently have protecting groups at the 3-position and the 5-position. Specifically, the following configurations can be mentioned. That is, the condensed aromatic ring or the condensed heteroaromatic ring, which is the lumophore, is bonded to two or more diphenylamino groups, and the phenyl groups in the two or more diphenylamino groups each independently have protecting groups at the 3-position and the 5-position. The protecting groups are at the 3-position and 5-position.

[0186] By adopting such a configuration, as shown in FIG. 3, the protecting group at the 3-position or 5-position on the phenyl group comes directly above the condensed aromatic ring or the condensed heteroaromatic ring, which is the lumophore, It can be taken. As a result, it can efficiently cover above and below the plane of the condensed aromatic ring or the condensed heteroaromatic ring, and can suppress energy transfer by the Dexter mechanism.

[0187] As the energy acceptor material as described above, for example, an organic compound represented by the following general formula (G1) or (G2) can be preferably used.

[0188]

Chemical formula

[0189] In general formulas (G1) and (G2), A represents a substituted or unsubstituted condensed aromatic ring having 10 to 30 carbon atoms or a substituted or unsubstituted condensed heteroaromatic ring having 10 to 30 carbon atoms, and Ar to Ar 1 and to Ar 6 each independently represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 13 carbon atoms, X 1 to X 12 each independently represents any one of a branched-chain 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 R to R 1 to R 10 each independently represents any one of hydrogen, 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 aromatic hydrocarbon group having 6 to 13 carbon atoms include a phenyl group, a biphenyl group, a naphthyl group, a fluorenyl group, etc. Note that the aromatic hydrocarbon group is not limited to these.

[0190] When the aromatic hydrocarbon group has a substituent, examples of the substituent include 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, a hexyl group, and other alkyl groups having 1 to 7 carbon atoms, and a cyclope ntyl group, a cyclohexyl group, a cycloheptyl group, an 8,9,10-trinorbornanyl group , and other cycloalkyl groups having 5 to 7 carbon atoms, and an aryl group having 6 to 12 carbon atoms such as a phenyl group, a naphthyl group, a biphenyl group.

[0191] In the general formula (G1), the substituted or unsubstituted condensed aromatic ring having 10 to 30 carbon atoms or the substituted or unsubstituted condensed heteroaromatic ring having 10 to 30 carbon atoms represents the above-mentioned light-emitting group, and the above-mentioned skeleton can be used. Further, in the general formulas (G1) and (G2), X to X 1 to X 12 represent a protecting group .

[0192] Further, in the general formula (G2), the protecting group is bonded to the quinacridone skeleton which is a light-emitting group via an arylene group. By adopting this configuration, the protecting group can be arranged so as to cover the light-emitting group , so that energy transfer by the Dexter mechanism can be suppressed. Note that , the protecting group may be directly bonded to the light-emitting group.

[0193] Further, as the energy acceptor material, an organic compound represented by the following general formula (G3) or (G4) can be preferably used.

[0194]

Chemical formula

[0195] In the general formulae (G3) and (G4), A is a substituted or unsubstituted fused aromatic ring having 10 to 30 carbon atoms. X represents an aromatic ring or a substituted or unsubstituted condensed heteroaromatic ring having 10 to 30 carbon atoms; 1 ~X 12 each independently represents a branched chain alkyl group having 3 to 10 carbon atoms, substituted or unsubstituted cycloalkyl groups having 3 to 10 carbon atoms; trialkylsilyl groups having 3 to 12 carbon atoms; represents any one of the groups.

[0196] It is also preferred that the protecting group is bonded to the luminophore via a phenylene group. By this, the protecting group can be placed to cover the luminophore, and thus the Dexter mechanism can be realized. In addition, the luminophore and the protecting group are connected to the phenylene group. When the phenylene group is bonded to the phenylene group via a protecting group, the protecting group can be represented by the general formula (G3) or ( As shown in G4), the two protecting groups are preferably attached at the meta position to the phenylene group. This structure allows the luminophores to be covered efficiently, making it possible to obtain a Dexter The organic compound represented by the general formula (G3) can suppress the energy transfer by the mechanism. An example of such a product is the above-mentioned 2tBu-mmtBuDPhA2Anth. That is, in one embodiment of the present invention, general formula (G3) is a particularly preferred example.

[0197] The energy acceptor material is an organic compound represented by the following general formula (G5): The material can be suitably used.

[0198] [ka]

[0199] In general formula (G5), X1 up to X 8 each independently represents any one of a branched-chain 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 R up to R 11 each independently 18 represents any one of hydrogen, a branched-chain alkyl group having 3 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 carbon atoms, a trialkylsilyl group having 3 to 12 carbon atoms, and a substituted or unsubstituted aryl group having 6 to 25 carbon atoms. Examples of the aryl group having 6 to 25 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, a spirofluorenyl group, etc. The aryl group having 6 to

[0200] 25 carbon atoms is not limited to these. When the aryl group has a substituent, examples of the substituent include the above-mentioned alkyl group having 1 to 10 carbon atoms, a branched-chain 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. Since the anthracene compound has a high luminescence quantum yield and a small area of the lumophore, the upper and lower sides of the anthracene plane can be efficiently covered by the protecting group. An example of the organic compound represented by the general formula (G5) is the above-mentioned 2tBu-mmtBuDPhA2Anth.

[0201] Examples of the compounds represented by the general formulas (G1) to (G5) are shown in the structural formulas (102) to (105) and (200) to (284) below. In addition, the general formulas (G1) to (G5

[0202] Further, examples of the compounds represented by the general formulas (G1) to (G5) are shown in the structural formulas (102) to (105) and (200) to (284). Note that the general formulas (G1) to (G5 ) The compounds listed are not limited to these. Also, the compounds represented by structural formulas (102) to (105) and those shown in (200) to (284) can be suitably used as the guest material of the light-emitting element of one aspect of the present invention . Note that the guest material is not limited to these.

[0203]

Chemical formula

[0204]

Chemical formula

[0205]

Chemical formula

[0206]

Chemical formula

[0207]

Chemical formula

[0208]

Chemical formula

[0209]

Chemical formula

[0210]

Chemical formula

[0211]

Chemical formula

[0212]

Chem.

[0213]

Chem.

[0214]

Chem.

[0215]

Chem.

[0216]

Chem.

[0217]

Chem.

[0218]

Chem.

[0219]

Chem.

[0220]

Chem.

[0221]

Chem.

[0222]

Chem.

[0223]

Chem.

[0224]

Chem.

[0225] In addition, an example of a material that can be suitably used as a guest material of the light-emitting element according to one aspect of the present invention is shown in Structural Formulas (100) and (101). Note that the guest material is not limited thereto.

[0226]

Chem.

[0227] When 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 Compound 133 is preferably small, specifically, greater than 0 eV and less than or equal to 0.2 eV.

[0228] Compound 133 preferably has a skeleton having hole-transporting properties and a skeleton having electron-transporting properties. Alternatively, Compound 133 preferably has a π-electron-excessive skeleton or an aromatic amine skeleton and a π-electron-deficient skeleton. By doing so, it becomes easier to form a donor-acceptor type excited state within the molecule. Furthermore, in order for the donor property and the acceptor property to both become strong within the molecule of Compound 133, it is preferable to have a structure in which a skeleton having electron-transporting properties and a skeleton having hole-transporting properties are directly bonded. Alternatively, a structure in which a π-electron-excessive skeleton or an aromatic skeleton and a π-electron-deficient skeleton are directly bonded is preferable. By doing so, it becomes easier to form a donor-acceptor type excited state within the molecule. Furthermore, in order for the donor property and the acceptor property to both become strong within the molecule of Compound 133, it is preferable to have a structure in which a skeleton having electron-transporting properties and a skeleton having hole-transporting properties are directly bonded. Alternatively, a π-electron-excessive skeleton or an aromatic amine skeleton and a π-electron-deficient skeleton are directly bonded is preferable. By doing so, it becomes easier to form a donor-acceptor type excited state within the molecule. Furthermore, in order for the donor property and the acceptor property to both become strong within the molecule of Compound 133, it is preferable to have a structure in which a skeleton having electron-transporting properties and a skeleton having hole-transporting properties are directly bonded. Alternatively, a π-electron-excessive skeleton or an aromatic skeleton and a π-electron-deficient skeleton are directly bonded is preferable. By doing so, it becomes easier to form a donor-acceptor type excited state within the molecule. Furthermore, in order for the donor property and the acceptor property to both become strong within the molecule of Compound 133, it is preferable to have a structure in which a skeleton having electron-transporting properties and a skeleton having hole-transporting properties are directly bonded. Alternatively, a π-electron-excessive skeleton or an aromatic Preferably, it has a structure in which the amine skeleton and the π-electron deficient skeleton are directly bonded. Within the molecule By enhancing both the donor property and the acceptor property of the overlapping region of the molecular orbital distribution in the HOMO of Compound 133 and the overlapping region of the molecular orbital distribution in the LUMO can be reduced and the energy difference between the singlet excitation energy level and the triplet excitation energy level of Compound 133 can be made smaller. Further, the triplet excitation energy level of Compound 133 can be kept at a high energy.

[0229] When the TADF material is composed of one type of material, for example, the following materials can be used.

[0230] First, fullerenes and their derivatives, acridine derivatives such as proflavine, eosin, etc. can be mentioned. Also, metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd), etc. can be mentioned. Examples of the metal-containing porphyrin include, for example, protoporphyrin- tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (Sn F2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF2(OEP)), etioporphyrin-tin fluoride complex (SnF2(E tio I)), octaethylporphyrin-platinum chloride complex (PtCl2OEP), etc. can be mentioned.

[0231] ​​​​​ [ka]

[0232] In addition, TADF materials that are composed of a single material include those with a π-electron-rich framework and a π-electron-deficient framework. Heterocyclic compounds having a biphenyl skeleton can also be used. -yl)-4,6-bis(12-phenylindolo[2,3-a]carbazole-11- 2-{4-[3-(N-phenyl)-1,3,5-triazine (abbreviation: PIC-TRZ), 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-diazine Drofenadine-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazo (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridine-10- 4-(9,9-diyl)-9H-xanthen-9-one (abbreviation: ACRXTN), bis[4-(9,9-diyl) Methyl-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 (abbreviation: 4PCCzBf pm), 4-[4-(9'-phenyl-3,3'-bi-9H-carbazol-9-yl) Phenyl]benzofuro[3,2-d]pyrimidine (abbreviation: 4PCCzPBfpm), 9- [3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9’- phenyl-2,3’-bi-9H-carbazole (abbreviation: mPCCzPTzn-02) and the like are mentioned. Since the heterocyclic compound has a π-electron-excessive heterocyclic aromatic ring and a π-electron-deficient heterocyclic aromatic ring, it has high electron transportability and hole transportability, which is preferable. Among them, among the skeletons having a π-electron-deficient heterocyclic aromatic ring, a pyridine skeleton, a diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), and a triazine skeleton are preferable because they are stable and have good reliability. In particular, a benzofuropyrimidine skeleton, a benzothienopyrimidine skeleton, a benzofuropyrazine skeleton, a benzothienopyrazine skeleton are preferable because they have high acceptor properties and good reliability. Also, among the skeletons having a π-electron-excessive heterocyclic aromatic ring, an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, a thiophene skeleton, and a pyrrole skeleton are stable and have good reliability, so it is preferable to have at least one of these skeletons. Note that as the furan skeleton, a dibenzofuran skeleton is preferable, and as the thiophene skeleton, a dibenzothiophene skeleton is preferable respectively. Also, as the pyrrole skeleton, an indole skeleton, a carbazole skeleton, a bi carbazole skeleton, a 3-(9-phenyl-9H-carbazol-3-yl)-9H-carb azole skeleton are particularly preferable. Note that a substance in which a π-electron-excessive heterocyclic aromatic ring and a π-electron-deficient heterocyclic aromatic ring are directly bonded has both strong donor properties of the π-electron-excessive heterocyclic aromatic ring and acceptor properties of the π-electron-deficient heterocyclic aromatic ring, and the difference between the singlet excited state level and the triplet excited state level is small, so it is particularly preferable. Note that instead of the π-electron-deficient heterocyclic aromatic ring, an aromatic ring bonded with an electron-withdrawing group such as a cyano group may be used.

[0233]

Chem.

[0234] When compound 133 does not have the function of converting triplet excitation energy into light emission, compound 1 As the combination of 31 and compound 133 or compound 131 and compound 134, a combination that forms an exciplex with each other is preferred, but there is no particular limitation. It is preferable that one has the function of transporting electrons and the other has the function of transporting holes. As compound 131, in addition to zinc and aluminum uminum-based metal complexes, oxadiazole derivatives, triazole derivatives, benzimidazole azole derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, pyrimidine derivatives, triazine derivatives, pyridine derivatives such as bipyridine derivatives and phenanthroline derivatives can be mentioned. As other examples, aromatic amines and carbazole derivatives can be mentioned.

[0235] In addition, the following hole-transporting materials and electron-transporting materials can be used.

[0236] As the hole-transporting material, a material with higher hole transportability than electrons can be used, and it is preferably a material having a hole mobility of 1 ×10 -6 cm 2 / Vs or more. Specifically aromatic amines, carbazole derivatives, aromatic hydrocarbons, stilbene derivatives, etc. can be used . Further, the hole-transporting material may be a polymer compound.

[0237] As these materials with high hole transportability, for example, as aromatic amine compounds, N,N’ ​-Di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDP PA), 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'-di amine (abbreviation: DNTPD), 1,3,5-tris[N-(4-diphenylaminophenyl yl)-N-phenylamino]benzene (abbreviation: DPA3B), etc. can be mentioned.

[0238] In addition, as the carbazole derivative, specifically, 3-[N-(4-diphenylamino phenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA1 ), 3,6-bis[N-(4-diphenylaminophenyl)-N-phenylamino]-9 -phenylcarbazole (abbreviation: PCzDPA2), 3,6-bis[N-(4-diphenyl laminophenyl)-N-(1-naphthyl)amino]-9-phenylcarbazole (abbreviation : PCzTPN2), 3-[N-(9-phenylcarbazol-3-yl)-N-phenyl lamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-bis[N- (9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarb azole (abbreviation: PCzPCA2), 3-[N-(1-naphthyl)-N-(9-phenylcarb azol-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1) etc. can be mentioned.

[0239] In addition, as the carbazole derivative, among others, 4,4'-di(N-carbazolyl)biphe Nil (abbreviation: CBP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene Zen (abbreviation: TCPB), 9-[4-(10-phenyl-9-anthryl)phenyl]- 9H-carbazole (abbreviation: CzPA), 1,4-bis[4-(N-carbazolyl)phenyl]- 2,3,5,6-tetraphenylbenzene, etc. can be used.

[0240] In addition, as the aromatic hydrocarbon, for example, 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)anthra- cene (abbreviation: DPPA), 2-tert-butyl-9,10-bis(4-phenylphenyl)- anthracene (abbreviation: t-BuDBA), 9,10-di(2-naphthyl)anthra- cene (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’ - Violanthrone, anthracene, tetracene, rubrene, perylene, 2,5,8,11- tetra(tert-butyl)perylene, etc. may be mentioned. In addition, pentacene, coronene, etc. can also be used. Thus, a hole mobility of 1×10 cm -6 / Vs or more, and it is more preferable to use an aromatic hydrocarbon having 14 to 42 carbon atoms. 2 / Vs or more hole mobility is more preferably used, and an aromatic hydrocarbon having 14 to 42 carbon atoms is used.

[0241] Note that the aromatic hydrocarbon may have a vinyl skeleton. Examples of the aromatic hydrocarbon having a vinyl group include, for example, 4,4'-bis(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi), 9,10-bis[4-(2,2-diphenylvinyl)phenyl] anthracene (abbreviation: DPVPA), etc. may be mentioned.

[0242] In addition, high hole-transporting materials such as poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphenylamine) (abbreviation: PVTPA), poly[N-(4-{N'-[4-(4-diphenyl amino)phenyl]phenyl-N'-phenylamino}phenyl)methacrylamide]( (abbreviation: PTPDMA), poly[N,N'-bis(4-butylphenyl)-N,N'-bis (phenyl)benzidine] (abbreviation: Poly-TPD), etc. can also be used. (phenyl)benzidine] (abbreviation: Poly-TPD), etc. can also be used. can also be used.

[0243] In addition, examples of high hole-transporting materials include, for example, 4,4'-bis[N-(1-naphthyl )-N-phenylamino]biphenyl (abbreviation: NPB or α-NPD), N,N'-bi s(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]tri phenylamine (abbreviation: MTDATA), 4,4’-bis[N-(spiro-9,9’- bifluorene-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 4- phenyl-4’-(9-phenylfluorene-9-yl)triphenylamine (abbreviation: B PAFLP), 4-phenyl-3’-(9-phenylfluorene-9-yl)triphenyl amine (abbreviation: mBPAFLP), N-(9,9-dimethyl-9H-fluorene-2- yl)-N-{9,9-dimethyl-2-[N’-phenyl-N’-(9,9-dimethyl- 9H-fluorene-2-yl)amino]-9H-fluorene-7-yl}phenylamine (abbreviation: DFLADFL), N-(9,9-dimethyl-2-diphenylamino-9H-f luorene-7-yl)diphenylamine (abbreviation: DPNF), 2-[N-(4-diphenyl amino phenyl)-N-phenylamino]spiro-9,9’-bifluorene (abbreviation: D PASF), 4-phenyl-4’-(9-phenyl-9H-carbazol-3-yl)tri phenylamine (abbreviation: PCBA1BP), 4,4’-diphenyl-4’’-(9-f enyl-9-H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1B P), 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: PCB NBB), 4-Phenyldiphenyl-(9-phenyl-9H-carbazol-3-yl) amine (abbreviation: PCA1BP), N,N’-Bis(9-phenylcarbazol-3-yl )-N,N’-diphenylbenzene-1,3-diamine (abbreviation: PCA2B), N,N’ ,N’’-Triphenyl-N,N’,N’’-tris(9-phenylcarbazol-3- yl)benzene-1,3,5-triamine (abbreviation: PCA3B), N-(4-Biphenyl )-N-(9,9-dimethyl-9H-fluorene-2-yl)-9-phenyl-9H-ca rbazole-3-amine (abbreviation: PCBiF), N-(1,1’-Biphenyl-4-yl )-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9- dimethyl-9H-fluorene-2-amine (abbreviation: PCBBiF), 9,9-Dimethyl- N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl] -fluorene-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phe nyl-9H-carbazol-3-yl)phenyl]-spiro-9,9’-bifluorene- 2-amine (abbreviation: PCBASF), 2-[N-(9-phenylcarbazol-3-yl )-N-phenylamino]spiro-9,9’-bifluorene (abbreviation: PCASF), 2, 7-Bis[N-(4-diphenylaminophenyl)-N-phenylamino]-spiro-9 ,9’-bifluorene (abbreviation: DPA2SF), N-[4-(9H-Carbazol-9- yl)phenyl]-N-(4-phenyl)phenylaniline (abbreviation: YGA1BP), N , N'-bis[4-(carbazol-9-yl)phenyl]-N,N'-diphenyl-9 , aromatic amines such as 9,9-dimethylfluorene-2,7-diamine (abbreviation: YGA2F), etc. Compounds etc. can be used. Also, 3-[4-(1-naphthyl)-phenyl]-9- phenyl-9H-carbazole (abbreviation: PCPN), 3-[4-(9-phenanthryl) -phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPPn), 3,3'-bi s(9-phenyl-9H-carbazole) (abbreviation: PCCP), 1,3-bis(N-carb azolyl)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: mmDBFFL Bi-II), 4,4',4''-(benzene-1,3,5-triyl)tri(dibenz furan) (abbreviation: DBF3P-II), 1,3,5-tri(dibenzothiophen-4-yl l)-benzene (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-f enyl-9H-fluorene-9-yl)phenyl]dibenzothiophene (abbreviation: DBTF LP-III), 4-[4-(9-phenyl-9H-fluorene-9-yl)phenyl] -6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), 4-[3-(tri enylene-2-yl)phenyl]dibenzothiophene (abbreviation: mDBTPTp-II), etc. amine compounds, carbazole compounds, thiophene compounds, furan compounds, fluorene compounds, triphenylene compounds, phenanthrene compounds, etc. can be used. The substances described here are mainly 1×10 cm -6 cm 2It is a substance having a hole mobility of 1 / Vs or more. However, as long as it is a substance with higher hole transportability than electrons, other substances may be used.

[0244] As the electron transport material, a material with higher electron transportability than holes can be used, and it is preferably a material having an electron mobility of 1 ×10 -6 cm 2 / Vs or more. As a material that easily accepts electrons (a material having electron transportability), π - electron - deficient heteroaromatic compounds such as nitrogen - containing heteroaromatic compounds and metal complexes can be used. Specifically, metal complexes having a quinoline ligand, a benzoquinoline ligand, an oxazole ligand, or a thiazole ligand, oxadiazole derivatives, triazole derivatives, phenanthroline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, etc. can be mentioned. For example, tris(8 - quinolinolato)aluminum(III) (abbreviation: Alq), tris(4 - methyl - 8 - quinolinolato)aluminum(III) (abbreviation: Almq3), bis(10 - hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq2 ), bis(2 - methyl - 8 - quinolinolato)(4 - phenylphenolato)aluminum(III) (abbreviation: BAlq), bis(8 - quinolinolato)zinc(II) (abbreviation: Znq) and the like, metal complexes having a quinoline skeleton or a benzoquinoline skeleton can be mentioned. Also,

[0245] in addition, metal complexes having oxazole - based or thiazole - based ligands such as bis[2 - (2 - benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnP BO), bis[2 - (2 - benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnB TZ) can also be used. ), bis(2 - methyl - 8 - quinolinolato)(4 - phenylphenolato)aluminum(III) (abbreviation: BAlq), bis(8 - quinolinolato)zinc(II) (abbreviation: Znq) III) (abbreviation: BAlq), bis(8 - quinolinolato)zinc(II) (abbreviation: Znq) and the like, metal complexes having a quinoline skeleton or a benzoquinoline skeleton can be mentioned. Also, in addition, metal complexes having oxazole - based or thiazole - based ligands such as bis[2 - (2 - benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnP BO), bis[2 - (2 - benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnB TZ) can also be used. It is possible. Furthermore, 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-biphe nyl)-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-(diben zothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation : mDBTBIm-II), bathophenanthroline (abbreviation: BPhen), 2,9-bis (naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBPhen), bathocuproine (abbreviation: BCP), and other heterocyclic compounds, 2-[3- (dibenzothiophen-4-yl)phenyl]dibenz[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3’-(dibenzothiophen-4-yl)biphenyl -3-yl]dibenz[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II) , 2-[3’-(9H-carbazol-9-yl)biphenyl-3-yl]dibenz[f ,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4-(3,6-diphenyl- 9H-carbazol-9-yl)phenyl]dibenz[f,h]quinoxaline (abbreviation: 2 CzPDBq-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: 6 mDBTPDBq-II), 4,6-bis[3-(phenanthren-9-yl)phenyl pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothie nyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis 3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2 Pm), and other 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), and other heterocyclic compounds having a triazine skeleton, such as 3,5-bis[3-(9H-carbazol-9-yl)phenyl pyridine (abbreviation: 35DCzPPy), 1,3,5-tri[3-(3-pyridyl) phenyl]benzene (abbreviation: TmPyPB), and other heterocyclic compounds having a pyridine skeleton, 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzO s), and other heteroaromatic compounds can also be used. In addition, polymers such as poly(2,5-pyridinediyl) (abbreviation: PPy), poly[(9,9-dihexylfluorene-2,7-diyl)-co- (pyridine-3,5-diyl)] (abbreviation: PF-Py), poly[(9,9-dioctyl fluorene-2,7-diyl)-co-(2,2'-bipyridine-6,6'-diyl) (abbreviation: PF-BPy) can also be used. The substances described here ​ The quality is mainly a substance having an electron mobility of 1×10 -6 cm 2 / Vs or more. In addition, as long as it is a substance with higher electron transportability than holes, substances other than the above may be used.

[0246] As the compound 133 or the compound 134, a material capable of forming an exciplex with the compound 131 is preferable. Specifically, the hole transport material and the electron transport material shown above can be used . In this case, it is preferable to select the compound 131 and the compound 133 or the compound 131 and the compound 134 such that the emission peak of the exciplex formed by them overlaps with the absorption band on the longest wavelength side ( low energy side) of the compound 132 (fluorescent material). By this , a light-emitting element with a dramatically improved luminous efficiency can be obtained.

[0247] In addition, as the compound 133, a phosphorescent material can be used. Examples of the phosphorescent material include iridium, rhodium, or platinum-based organometallic complexes, or metal complexes. In addition, platinum complexes and organoiridium complexes having porphyrin ligands can be mentioned. Among them, for example, organoiridium complexes such as iridium-based orthometal complexes are preferable. Examples of the ligand for orthometalation include 4H-triazole ligand, 1H-triazole ligand, imidazole ligand, pyridine ligand, pyrimidine ligand, pyrazine ligand, or isoquinoline ligand, etc. In this case, the compound 133 (phosphorescent material) has an absorption band of triplet MLCT (Metal to Ligand Charge Transfer) transition It has. Also, the emission peak of Compound 133 overlaps with the absorption band on the longest wavelength side (lower energy side) of Compound 132 (fluorescent material). It is preferable to select Compound 133 and Compound 132 (fluorescent material). As a result, a light-emitting device with a dramatically improved luminous efficiency can be obtained. Also, even when Compound 133 is a phosphorescent material, it may form an exciplex with Compound 131. When forming an exciplex, the phosphorescent material does not need to emit light at room temperature, as long as it can emit light at room temperature when the exciplex is formed. In this case, for example, Ir(ppy)3 etc. can be used as the phosphorescent material. Substances having an emission peak in blue or green include, for example, tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN]phenyl-κC}iridium(III) (abbreviation: Ir(mpptz-dmp)3), tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III) (abbreviation: Ir(Mptz)3), tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: Ir(iPrptz-3b)3), tris[3-(5-biphenyl)-5-isopropyl-4-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: Ir(iPr5btz)3), etc., organometallic iridium complexes having a 4H-triazole skeleton, and tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviation: Ir

[0248] 2 (Mptz1-mp)3), Tris(1-methyl-5-phenyl-3-propyl-1H- 1,2,4-triazolato)iridium(III) (abbreviation: Ir(Prptz1-Me) 3) and other organometallic iridium complexes having a 1H-triazole skeleton, such as fac-tri s[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium (III) (abbreviation: Ir(iPrpmi)3), tris[3-(2,6-dimethyl phenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(II II) (abbreviation: Ir(dmpimpt-Me)3) and other organometallic iridium complexes having an imidazole skeleton, and bis[2-(4’,6’-difluorophenyl)pyridinato- N,C iridium(III) tetrakis(1-pyrazolyl)borate (abbreviation: Fir 2’ 6), bis[2-(4’,6’-difluorophenyl)pyridinato-N,C iridium 2’ (III) picolinate (abbreviation: Firpic), bis{2-[3’,5’-bis (trifluoromethyl)phenyl]pyridinato-N,C }}iridium(III) pico 2’ (linate (abbreviation: Ir(CF3ppy)2(pic)), bis[2-(4’,6’-dif luorophenyl)pyridinato-N,C iridium(III) acetylacetonate 2’ (abbreviation: Fir(acac)) and other organometallic iridium complexes having a phenylpyridine derivative having an electron-withdrawing group as a ligand. 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 have high triplet excitation energy and reliability and luminescence efficiency . ​​Since it is also excellent, it is particularly preferable.

[0249] In addition, examples of substances having a luminescence peak in green or yellow include, for example, tris(4-methyl -6-phenylpyrimidinato)iridium(III) (abbreviation: Ir(mppm)3), tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation: I r(tBuppm)3), (acetylacetonato)bis(6-methyl-4-phenylpyr imidinato)iridium(III) (abbreviation: Ir(mppm)2(acac)), (acetyl acetonato)bis(6-tert-butyl-4-phenylpyrimidinato)iridium( III) (abbreviation: Ir(tBuppm)2(acac)), (acetylacetonato)bis [4-(2-norbornyl)-6-phenylpyrimidinato]iridium(III) (abbreviation : Ir(nbppm)2(acac)), (acetylacetonato)bis[5-methyl-6 -(2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: Ir(mpmppm)2(acac)), (acetylacetonato)bis{4,6-dimethyl -2-[6-(2,6-dimethylphenyl)-4-pyrimidinyl-κN 3 phenyl- κC}iridium(III) (abbreviation: Ir(dmppm-dmp)2(acac)), ( acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III)( abbreviation: Ir(dppm)2(acac)) and other organometallic iri dium complexes having a pyrimidine skeleton, (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazina to)iridium(III) (abbreviation: Ir(mppr-Me)2(acac)), (acetyl Ruthenium(III) bis(5-isopropyl-3-methyl-2-phenylpyrazinato)(acetylacetonato) (abbreviation: Ir(mppr-iPr)2(acac)) and other organometallic iridium complexes having a pyrazine skeleton, tris(2-phenylpyridinato-N,C ), iridium(III) (abbreviation: Ir(ppy)3), bis(2-phenylpyridinato-N 2’ ),C) iridium(III) acetylacetonate (abbreviation: Ir(ppy)2(ac ,C 2’ ) acetylacetonate (abbreviation: Ir(ppy)2(ac ac)), bis(benzo[h]quinolinato)iridium(III) acetylacetonate (abbreviation: Ir(bzq)2(acac)), tris(benzo[h]quinolinato)iridium (III) (abbreviation: Ir(bzq)3), tris(2-phenylquinolinato-N,C 2 ’ ) iridium(III) (abbreviation: Ir(pq)3), bis(2-phenylquinolinato- N,C 2’ ) iridium(III) acetylacetonate (abbreviation: Ir(pq)2(ac ac)) and other organometallic iridium complexes having a pyridine skeleton, bis(2,4-dif enyl-1,3-oxazolato-N,C 2’ ) iridium(III) acetylacetonate (abbreviation: Ir(dpo)2(acac)), bis{2-[4’-(perfluorophenyl yl)phenyl]pyridinato-N,C 2’} iridium(III) acetylacetonate ( abbreviation: Ir(p-PF-ph)2(acac)), bis(2-phenylbenzothiazolato -N,C 2’ ) iridium(III) acetylacetonate (abbreviation: Ir(bt)2(a cac)) and other organometallic iridium complexes, tris(acetylacetonato)(monophen such as terbium(III) tris(acetylacetonato)(1,10-phenanthroline) (abbreviation: Tb(acac)3(Phen)) Among the above, organometallic iridium complexes having a pyrimidine skeleton are particularly preferred because of their outstanding reliability and luminescence efficiency.

[0250] In addition, examples of substances having a luminescence peak in yellow or red include (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III) (abbreviation: Ir(5mdppm)2(dibm)), bis[4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: Ir(5mdppm)2(dpm)), bis[4,6-di(naphthalen-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: Ir(d1npm)2(dpm)) and other organometallic iridium complexes having a pyrimidine skeleton, (acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: Ir(tppr)2(acac)), bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: Ir(tppr)2(dpm)), (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: Ir(Fdpq)2(acac)) and other organometallic iridium complexes having a pyrazine skeleton, tris(1-phenylisoquinolinato-N,C)iridium(III) (abbreviation: Ir(piq)3), bis(1-phenylisoquinolinato-N,C)iridium(III) acetylacetonate (abbreviation: Ir(piq)2(acac)) (III)) (III)) (III)) (III)) (III)) (III)) 2’ ) 2’ (acac)) ​​​​​​​​​In addition to the organometallic iridium complex having a pyridine skeleton such as acac), 2,3,7, 8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum(II )(abbreviation: PtOEP), platinum complexes such as, tris(1,3-diphenyl-1,3-prop anedionato)(monophenanthroline) europium(III)(abbreviation: Eu(DB M)3(Phen)), tris[1-(2-thenoyl)-3,3,3-trifluoroac etionato](monophenanthroline) europium(III)(abbreviation: Eu(TTA)3( Phen)) and other rare earth metal complexes can be mentioned. Among the above, the organometallic iridium complex having a pyrimidine skeleton is particularly preferable because of its outstanding reliability and luminescence efficiency. In addition, an organometallic iridium complex having a pyrazine skeleton can obtain red luminescence with good chromaticity.

[0251] In addition, materials that can be used as the above energy donors include metal halide perovskites. The metal halide perovskites can be represented by any of the following general formulas (g1) to (g3).

[0252] (SA)MX3: (g1) (LA)2(SA) n-1 M n X 3n+1 : (g2) (PA)(SA) n-1 M n X3 n+1 : (g3)

[0253] In the above general formula, M represents a divalent metal ion, and X represents a halogen ion.

[0254] Specifically, divalent metal ions such as lead and tin are used as the divalent metal ions. 。

[0255] As the halogen ion, specifically, anions such as chlorine, bromine, iodine, and fluorine are used. are used.

[0256] Also, n represents an integer from 1 to 10. However, in general formula (g2) or general formula (g3), when n is greater than 10, its properties become similar to those of the metal halide perovskites represented by general formula (g1). when n is greater than 10, its properties become similar to those of the metal halide perovskites represented by general formula (g1). perovskites.

[0257] Also, LA represents an ammonium ion represented by R 30 -NH3 + represents an ammonium ion represented by R

[0258] In the ammonium ion represented by the general formula R 30 -NH3 + in the ammonium ion represented by the general formula R 30 is any 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, an alkylene group having 1 to 12 carbon atoms, a vinylene group, an arylene group having 6 to 13 carbon atoms, and a heteroarylene group. In the latter case, the alkylene group, the arylene group, and the heteroarylene group may be connected in series, and a plurality of the same type of group may be used. Note that when the alkylene group, the vinylene group, the arylene group, and the heteroarylene group are connected in series, the total number of the alkylene group, the vinylene group, the arylene group, and the heteroarylene group is preferably 35 or less. group, the vinylene group, the arylene group, and the heteroarylene group may be connected in series, and a plurality of the same type of group may be used. Note that when the alkylene group, the vinylene group, the arylene group, and the heteroarylene group are connected in series, the total number of the alkylene group, the vinylene group, the arylene group, and the heteroarylene group is preferably 35 or less. is preferable.

[0259] Also, SA is represented by a monovalent metal ion or R 31 -NH3 + is represented by R 31 is 1 to It represents an ammonium ion with an alkyl group of 6.

[0260] Also, PA is 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, and the valence of the part is +2. Note that the charges in the general formula are approximately balanced. .

[0261] Here, the charges of metal halide perovskites are not exactly balanced in all parts of the material according to the above formula, and it is only necessary that the neutrality of the whole material is generally maintained. There may be other ions such as free ammonium ions, free halogen ions, and impurity ions in the material, and they may neutralize the charges. . Also, there may be cases where neutrality is not locally maintained on the surface of particles or films, at grain boundaries of crystals, etc., and it is not necessary for neutrality to be maintained at all locations. There may be cases where they neutralize the charges. . Also, there may be cases where neutrality is not locally maintained at the surface of particles or films, at grain boundaries of crystals, etc., and it is not necessary for neutrality to be maintained at all locations. That is, it is not necessary for neutrality to be maintained at all locations.

[0262] Note that for (LA) in the above formula (g2), substances represented by the following general formulas (a-1) to (a-1 1), general formulas (b-1) to (b-6), etc. can be used.

[0263]

Chemical formula

[0264]

Chemical formula

[0265] In the general formula (g3), (PA) typically represents a substance represented by any of the following general formulas (c-1), (c -2), and (d), and a branched polyethyleneimine having an ammonium cation, etc., and represents a part or all of them, and has a +2 valence charge. These polymers may neutralize the charge over a plurality of unit cells, and in some cases, the charge of one unit cell may be neutralized by each of the charges of two different polymer molecules. These polymers may neutralize the charge over a plurality of unit cells, and in some cases, the charge of one unit cell may be neutralized by each of the charges of two different polymer molecules. These polymers may neutralize the charge over a plurality of unit cells, and in some cases, the charge of one unit cell may be neutralized by each of the charges of two different polymer molecules. These polymers may neutralize the charge over a plurality of unit cells, and in some cases, the charge of one unit cell may be neutralized by each of the charges of two different polymer molecules.

[0266]

Chemical formula

[0267]

Chemical formula

[0268] However, in the above general formula, R 20 represents an alkyl group having 2 to 18 carbon atoms, R 21 , R 2 2 and R 23 represent hydrogen or an alkyl group having 1 to 18 carbon atoms, R 24 represents the following structural formula and general formulas (R 24 -1) to (R 24 -14). Also, R 25 and R 26 each independently represent hydrogen or an alkyl group having 1 to 6 carbon atoms. Further, X has a combination of monomer units A and B represented by any of the above (d-1 ) to (d-6), and represents a structure in which u of A and v of B are contained. The order of A and B is not limited. Also, m and l are each independently an integer from 0 to 12, and t is from 1 to not limited. Also, m and l are each independently an integer from 0 to 12, and t is from 1 to not limited. Also, m and l are each independently an integer from 0 to 12, and t is from 1 to is an integer of 18. Further, u is an integer from 0 to 17, v is an integer from 1 to 18, and u + v is an integer from 1 to 18.

[0269] [Chemical Formula]

[0270] Note that these are examples, and the substances that can be used as (LA) and (PA) are not limited to these alone.

[0271] A metal halide having a three-dimensional structure with a composition of (SA)MX3 represented by the general formula (g1) In perovskites, a metal atom M is placed at the center and halogen atoms are arranged at six vertices to form a regular octahedral structure. The halogen atoms at each vertex share to form a three-dimensional array to form a skeleton This regular octahedral structural unit with a halogen atom at each vertex is called a perovskite unit A zero-dimensional structure in which this perovskite unit exists in isolation, A linear structure connected one-dimensionally through the halogen atoms at the vertices, a sheet-like structure connected two-dimensionally, A three-dimensionally connected structure, and there is also a complex two-dimensional structure formed by stacking multiple layers of a sheet-like structure in which perovskite units are connected two-dimensionally. Furthermore, There are even more complex structures. A general term for all structures having these perovskite units is defined and used as metal halide perovskites.

[0272] Note that the light-emitting layer 130 can also be composed of two or more layers. For example, when the first light-emitting layer and the second light-emitting layer are stacked in order from the hole transport layer side to form the light-emitting layer 130, a substance having hole transport properties is used as the host material of the first light-emitting layer, and the host material of the second light-emitting layer​ There is a configuration in which a substance having electron transporting properties is used as such.

[0273] Further, in the light emitting layer 130, it may have a material (compound 135) other than compound 131, compound 132, compound 133, and compound 134. In that case, in order for compound 131 and compound 133 (or compound 134) to efficiently form an exciplex, one of compound 13 1 and compound 133 (or compound 134) has the highest HOMO level among the materials in the light emitting layer 130 and the other has the lowest LUMO level among the materials in the light emitting layer 130. By having such a correlation of energy levels, the reaction of forming an exciplex between compound 131 and compound 135 can be suppressed. It is possible.

[0274] For example, when compound 131 has hole transporting properties and compound 133 (or compound 134) has electron transporting properties, it is preferable that the HOMO level of compound 131 is higher than the HOMO levels of compound 133 and compound 135, and it is preferable that the LUMO level of compound 133 is lower than the LUMO levels of compound 131 and compound 135. In this case, the LUMO level of compound 135 may be higher or lower than the LUMO level of compound 131. Also, the HOMO level of compound 135 may be higher or lower than the HOMO level of compound 133.

[0275] The material (compound 135) that can be used for the light emitting layer 130 is not particularly limited, but for example, tris(8-quinolinolato)aluminum(III) (abbreviation: Alq), tris tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviation: Almq3), bis​ Beryllium(II) (10-hydroxybenzo[h]quinolinato) (abbreviation: BeBq2 ), aluminum(III) bis(2-methyl-8-quinolinolato)(4-phenylphenolato) ( abbreviation: BAlq), zinc(II) bis(8-quinolinolato) (abbreviation: Znq) , zinc(II) bis[2-(2-benzoxazolyl)phenolato] (abbreviation: ZnPBO ), zinc(II) bis[2-(2-benzothiazolyl)phenolato] (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-oxadiazol-2-yl]benzene (abbreviation: OX D-7), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphen yl)-1,2,4-triazole (abbreviation: TAZ), 2,2’,2’’-(1,3,5 -benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TP BI), 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, 4,4’-bis[N-( 1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB or α-NPD), N,N’-bis(3-methylphenyl)-N,N’-diphenyl-[1,1’-bipheny yl]-4,4’-diamine (abbreviation: TPD), 4,4’-bis[N-(spiro-9,9’ -bifluorene-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), etc. Examples of the aromatic amine compound include. Also, anthracene derivatives, phenanthrene derivatives , condensed polycyclic aromatic compounds such as pyrene derivatives, chrysene derivatives, dibenzo[g,p]chrysene derivatives, etc., specifically, 9,10-diphenylanthracene (abbreviation: DPAnth), N,N-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl -9H-carbazole-3-amine (abbreviation: CzA1PA), 4-(10-phenyl- 9-anthryl)triphenylamine (abbreviation: DPhPA), 4-(9H-carbazole -9-yl)-4'-(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-(9,1 0-diphenyl-2-anthryl)-9H-carbazole-3-amine (abbreviation: 2PCAPA ), 6,12-dimethoxy-5,11-diphenylchrysene, N,N,N',N', N'',N'',N''',N''' - octaphenyldibenzo[g,p]chrysene-2 ,7,10,15-tetraamine (abbreviation: DBC1), 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'-di yl)diphenanthrene (abbreviation: DPNS2), 3,3',3''-(benzene-1,3 ,5-triyl)tripyrene (abbreviation: TPB3), etc. can be mentioned. Also, from these and known substances, substances having an energy gap larger than that of the above-mentioned compound 131 and compound 132 can be selected and used singly or in combination of two or more . .

[0276] ≪A pair of electrodes≫ The electrode 101 and the electrode 102 have a function of injecting holes and electrons into the light-emitting layer 130. The electrode 101 and the electrode 102 can be formed using a metal, an alloy, a conductive compound, and mixtures or laminates thereof . As the metal, aluminum (Al) is a typical example, and other 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) can be used. Rare earth metals such as ytterbium (Yb) can also be used as the transition metal. As the alloy, alloys containing the above metals can be used, for example, MgAg, AlLi, etc. can be mentioned. As the conductive compound, for example, indium tin oxide (Indium Tin Oxide, hereinafter ITO), indium tin oxide containing silicon or silicon oxide (abbreviation: ITSO), indium zinc oxide (Indium Z n), etc. can be used. Silicon or silicon oxide can also be used alone Metal oxides such as indium oxide containing indium (In), tungsten, and zinc can be mentioned. As the conductive compound, an inorganic carbon-based material such as graphene may be used. As described above, one or both of the electrode 101 and the electrode 10 2 may be formed by laminating a plurality of these materials.

[0277] In addition, the light emitted from the light-emitting layer 130 is taken out through one or both of the electrode 101 and the electrode 102. Therefore, at least one of the electrode 101 and the electrode 102 has a function of transmitting visible light. As the conductive material having the function of transmitting light, the visible light transmittance is 40% or more and 100% or less, preferably 60% or more and 100% or less, and its resistance rate is 1×10 Ω·cm or less of conductive materials can be mentioned. In addition, the electrode for taking out light may be formed of a conductive material having a function of transmitting light and a function of reflecting light. As the conductive material, the reflectance of visible light is 20% or more and 80% or less, preferably 4 0% or more and 70% or less, and its resistivity is 1×10 -2 Ω·cm or less of conductive materials can be mentioned. When a material with low light transmittance such as metal or alloy is used for the electrode for taking out light it is sufficient to form one or both of the electrode 101 and the electrode 102 with a thickness that allows visible light to pass through (for example, a thickness of 1 nm to 10 nm). -2

[0278] In addition, in this specification and the like, for the electrode having the function of transmitting light, a material having the function of transmitting visible light and having conductivity may be used. For example, in addition to the oxide conductor layer typified by ITO as described above, an oxide semiconductor layer or an organic conductor layer containing an organic substance may be included. . Examples of the organic conductive layer containing an organic substance include a layer containing a composite material formed by mixing an organic compound and an electron donor, a layer containing a composite material formed by mixing an organic compound and an electron acceptor, and the like. Further, the resistivity of the transparent conductive layer is preferably 1 × 10 Ω·cm or less, more preferably 1 × 10 Ω·cm or less. 5 4

[0279] In addition, the film formation methods of the electrodes 101 and 102 can be appropriately used, such as sputtering method, evaporation method, printing method, coating method, MBE (Molecular Beam Epitaxy) method, CVD method, pulse laser deposition method, ALD (Atomic Layer Deposition) method, etc.

[0280] ≪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 by, for example, transition metal oxides, phthalocyanine derivatives, or aromatic amines. Examples of the transition metal oxides include molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, manganese oxide, etc. Examples of the phthalocyanine derivatives include phthalocyanine and metal phthalocyanine, etc. Examples of the aromatic amines include benzidine derivatives and phenylenediamine derivatives. Polymer compounds such as polythiophene and polyaniline can also be used, and for example, poly(ethylenedioxythiophene) / poly(styrenesulfonic acid), which is self-doped polythiophene, is a representative example.

[0281] ​​​​​​​​​As the positive hole injection layer 111, a layer having a composite material of a hole transporting material and a material exhibiting electron accepting properties with respect to this can also be used. Alternatively, a laminate of a layer containing a material exhibiting electron accepting properties and a layer containing a hole transporting material may be used. Charge transfer is possible between these materials in a steady state or in the presence of an electric field. Examples of the material exhibiting electron accepting properties include organic acceptors such as quinodimethane derivatives, chloranil derivatives, and hexaazatriphenylene derivatives. Specifically, 7,7,8,8 - tetracyano - 2,3,5,6 - tetrafluorobenzoquinodimethane (abbreviation: F4 - TCNQ), chloranil, 2,3,6,7,10,11 - hexacyano - 1,4,5,8,9,12 - hexaazatriphenylene (abbreviation: HAT - CN), 1,3,4,5,7,8 - hexafluorotetracyano - naphthoquinodimethane (abbreviation: F6 - TCNNQ), and other compounds having an electron - withdrawing group (particularly a halogen group such as a fluoro group or a cyano group) 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 preferred. Also, [3]radialene derivatives having an electron - withdrawing group (particularly a halogen group such as a fluoro group or a cyano group) are preferred because of their very high electron - accepting properties. Specifically, α,α’,α’’ - 1,2,3 - cyclopropanetriylidene tris[4 - cyano - 2,3,5,6 - tetrafluorobenzeneacetonitrile], α,α’,α’’ - 1,2,3 - cyclopropanetriylidene tris[2,6 - dichloro - 3,5 - difluoro - 4 - (trifluoromethyl)benzeneacetonitrile], α,α’,α’’ - 1,2,3 - cyclopropanetriylidene tris[2,3,4,5,6 - pentafluorobenzeneacetonitrile] can be mentioned. These materials can transfer charges between them in a steady state or in the presence of an electric field. Examples of the material exhibiting electron accepting properties include organic acceptors such as quinodimethane derivatives, chloranil derivatives, and hexaazatriphenylene derivatives. Specifically, 7,7,8,8 - tetracyano - 2,3,5,6 - tetrafluorobenzoquinodimethane (abbreviation: F4 - TCNQ), chloranil, 2,3,6,7,10,11 - hexacyano - 1,4,5,8,9,12 - hexaazatriphenylene (abbreviation: HAT - CN), 1,3,4,5,7,8 - hexafluorotetracyano - naphthoquinodimethane (abbreviation: F6 - TCNNQ), and other compounds having an electron - withdrawing group (particularly a halogen group such as a fluoro group or a cyano group) 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 preferred. Also, [3]radialene derivatives having an electron - withdrawing group (particularly a halogen group such as a fluoro group or a cyano group) are preferred because of their very high electron - accepting properties. Specifically, α,α’,α’’ - 1,2,3 - cyclopropanetriylidene tris[4 - cyano - 2,3,5,6 - tetrafluorobenzeneacetonitrile], α,α’,α’’ - 1,2,3 - cyclopropanetriylidene tris[2,6 - dichloro - 3,5 - difluoro - 4 - (trifluoromethyl)benzeneacetonitrile], α,α’,α’’ - 1,2,3 - cyclopropanetriylidene tris[2,3,4,5,6 - pentafluorobenzeneacetonitrile] 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 preferred. Also, [3]radialene derivatives having an electron - withdrawing group (particularly a halogen group such as a fluoro group or a cyano group) are preferred because of their very high electron - accepting properties. Specifically, α,α’,α’’ - 1,2,3 - cyclopropanetriylidene tris[4 - cyano - 2,3,5,6 - tetrafluorobenzeneacetonitrile], α,α’,α’’ - 1,2,3 - cyclopropanetriylidene tris[2,6 - dichloro - 3,5 - difluoro - 4 - (trifluoromethyl)benzeneacetonitrile], α,α’,α’’ - 1,2,3 - cyclopropanetriylidene tris[2,3,4,5,6 - pentafluorobenzeneacetonitrile] can be mentioned. Specifically, α,α’,α’’ - 1,2,3 - cyclopropanetriylidene tris[4 - cyano - 2,3,5,6 - tetrafluorobenzeneacetonitrile], α,α’,α’’ - 1,2,3 - cyclopropanetriylidene tris[2,6 - dichloro - 3,5 - difluoro - 4 - (trifluoromethyl)benzeneacetonitrile], α,α’,α’’ - 1,2,3 - cyclopropanetriylidene tris[2,3,4,5,6 - pentafluorobenzeneacetonitrile] Specifically, α,α’,α’’ - 1,2,3 - cyclopropanetriylidene tris[4 - cyano - 2,3,5,6 - tetrafluorobenzeneacetonitrile], α,α’,α’’ - 1,2,3 - cyclopropanetriylidene tris[2,6 - dichloro - 3,5 - difluoro - 4 - (trifluoromethyl)benzeneacetonitrile], α,α’,α’’ - 1,2,3 - cyclopropanetriylidene tris[2,3,4,5,6 - pentafluorobenzeneacetonitrile] Specifically, α,α’,α’’ - 1,2,3 - cyclopropanetriylidene tris[4 - cyano - 2,3,5,6 - tetrafluorobenzeneacetonitrile], α,α’,α’’ - 1,2,3 - cyclopropanetriylidene tris[2,6 - dichloro - 3,5 - difluoro - 4 - (trifluoromethyl)benzeneacetonitrile], α,α’,α’’ - 1,2,3 - cyclopropanetriylidene tris[2,3,4,5,6 - pentafluorobenzeneacetonitrile] Specifically, α,α’,α’’ - 1,2,3 - cyclopropanetriylidene tris[4 - cyano - 2,3,5,6 - tetrafluorobenzeneacetonitrile], α,α’,α’’ - 1,2,3 - cyclopropanetriylidene tris[2,6 - dichloro - 3,5 - difluoro - 4 - (trifluoromethyl)benzeneacetonitrile], α,α’,α’’ - 1,2,3 - cyclopropanetriylidene tris[2,3,4,5,6 - pentafluorobenzeneacetonitrile] Specifically, α,α’,α’’ - 1,2,3 - cyclopropanetriylidene tris[4 - cyano - 2,3,5,6 - tetrafluorobenzeneacetonitrile], α,α’,α’’ - 1,2,3 - cyclopropanetriylidene tris[2,6 - dichloro - 3,5 - difluoro - 4 - (trifluoromethyl)benzeneacetonitrile], α,α’,α’’ - 1,2,3 - cyclopropanetriylidene tris[2,3,4,5,6 - pentafluorobenzeneacetonitrile] Examples thereof include. Further, transition metal oxides, for example, oxides of metals from Group 4 to Group 8 can be used. Specifically, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, rhenium oxide, etc. Among them, molybdenum oxide is preferable because it is stable in the atmosphere, has low hygroscopicity, and is easy to handle.

[0282] As the hole transporting material, a material having higher hole transportability than electrons can be used, and it is preferably a material having a hole mobility of 1 × 10 cm -6 / Vs or more. Specifically, 2 the aromatic amines and carbazole derivatives mentioned as hole transporting materials that can be used in the light emitting layer 130 can be used. Further, aromatic hydrocarbons and stilbene derivatives, etc. can be used. Also, the hole transporting material may be a polymer compound. As the aromatic hydrocarbon, for example, 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-t

[0283] ert-butylanthracene (abbreviation: t-BuAnth), 9,10-bis(4-methyl -1-naphthyl)anthracene (abbreviation: DMNA), 2-tert-butyl-9,10- (abbreviation: DMNA), 2-tert-butyl-9,10- anthracene (abbreviation: t-BuAnth), 9,10-bis(4-methyl )anthracene (abbreviation: DMNA), 2-tert-butyl-9,10- (abbreviation: DMNA), 2-tert-butyl-9,10- ert-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-naph thyl)phenyl]anthracene, 2,3,6,7-tetramethyl-9,10-di(1-naph thyl)anthracene, 2,3,6,7-tetramethyl-9,10-di(2-naphthyl) anthracene, 9,9'-bianthryl, 10,10'-diphenyl-9,9'-bianth ryl, 10,10'-bis(2-phenylphenyl)-9,9'-bianthryl, 10 ,10'-bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9'-bia nthryl, anthracene, tetracene, rubrene, perylene, 2,5,8,11-tetra (tert-butyl)perylene, etc. may be mentioned. In addition, pentacene, coronene, etc. can also be used. Thus, it is more preferable to use an aromatic hydrocarbon having a hole mobility of 1×10 -6 cm 2 / Vs or more and having 14 or more and 42 or less carbon atoms. Note that the aromatic hydrocarbon may have a vinyl skeleton. Examples of the aromatic hydrocarbon having a vinyl group include 4,4'-bis(2,2-diphenylvinyl)biphenyl

[0284] (abbreviation: DPVBi), 9,10-bis[4-(2,2-diphenylvinyl)phenyl] anthracene (abbreviation: DPVPA), etc. (abbreviation: DPVBi), 9,10-bis[4-(2,2-diphenylvinyl)phenyl] anthracene (abbreviation: DPVPA), etc.

[0285] In addition, poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphe nylamine) (abbreviation: PVTPA), poly[N-(4-{N'-[4-(4-diphenyl amino)phenyl]phenyl-N'-phenylamino}phenyl)methacrylamide]( abbreviation: PTPDMA), poly[N,N'-bis(4-butylphenyl)-N,N'-bis It is also possible to use a polymer compound such as (phenyl)benzidine (abbreviation: Poly-TPD). It is possible.

[0286] ≪Hole transport layer≫ The hole transport layer 112 is a layer containing a hole transporting material, and the materials exemplified as the material of the hole injection layer 111 can be used. Since the hole transport layer 112 has a function of transporting the holes injected into the hole injection layer 111 to the light emitting layer 130, it preferably has the same or a nearly the same HOMO level as that of the hole injection layer 111. As the above hole transporting material, the materials exemplified as the material of the hole injection layer 111 can be used. Further, it is preferably a substance having a hole mobility of 1×10 cm / Vs or more. However, as long as it is a substance having higher hole transportability than electrons, other substances may be used. Note that the layer containing a substance having high hole transportability may be not only a single layer but also two or more layers of the layers made of the above substances laminated.

[0287] As the above hole transporting material, the materials exemplified as the material of the hole injection layer 111 can be used. Further, it is preferably a substance having a hole mobility of 1×10 cm -6 / Vs or more. However, as long as it is a substance having higher hole transportability than electrons, other substances may be used. Note that the layer containing a substance having high hole transportability may be not only a single layer but also two or more layers of the layers made of the above substances laminated. 2 / Vs or more. However, as long as it is a substance having higher hole transportability than electrons, other substances may be used. Note that the layer containing a substance having high hole transportability may be not only a single layer but also two or more layers of the layers made of the above substances laminated. As the above hole transporting material, the materials exemplified as the material of the hole injection layer 111 can be used. Further, it is preferably a substance having a hole mobility of 1×10 cm / Vs or more. However, as long as it is a substance having higher hole transportability than electrons, other substances may be used. Note that the layer containing a substance having high hole transportability may be not only a single layer but also two or more layers of the layers made of the above substances laminated.

[0288] ≪Electron transport layer≫ The electron transport layer 118 has a function of transporting the 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. As the electron transporting material, a material having higher electron transportability than holes can be used, and it is preferably a material having an electron mobility of 1×10 cm / Vs or more. As the compound (material having electron transportability) that easily receives electrons, a π electron deficient heteroaromatic such as a nitrogen-containing heteroaromatic compound or a metal complex can be used. Specifically, those used for the light emitting layer 130 -6 cm 2 / Vs or more. As the compound (material having electron transportability) that easily receives electrons, a π electron deficient heteroaromatic such as a nitrogen-containing heteroaromatic compound or a metal complex can be used. Specifically, those used for the light emitting layer 130 cm / Vs or more. As the compound (material having electron transportability) that easily receives electrons, a π electron deficient heteroaromatic such as a nitrogen-containing heteroaromatic compound or a metal complex can be used. Specifically, those used for the light emitting layer 130 Examples of the electron-transporting material capable of this include metal complexes having a quinoline ligand, a benzoquinoline ligand, an oxazole ligand, or a thiazole ligand. Further, examples thereof include oxadiazole derivatives, triazole derivatives, phenanthroline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, etc. Further, it is preferable that the material has an electron mobility of 1×10 cm / Vs or more. Note that, as long as the material has higher electron transportability than holes, materials other than the above may be used as the electron transport layer. Further, the electron transport layer 118 may be not only a single layer, but also two or more layers made of the above materials laminated. -6 cm 2 / Vs Moreover, it is preferable that the material has an electron mobility of 1×10 cm / Vs or more. As long as the material has higher electron transportability than holes, materials other than the above may be used as the electron transport layer. Further, the electron transport layer 118 may be not only a single layer, but also two or more layers made of the above materials laminated.

[0289] Further, a layer for controlling the movement of electron carriers may be provided between the electron transport layer 118 and the light-emitting layer 130. The layer for controlling the movement of electron carriers is a layer in which a small amount of a substance having high electron trapping property is added to a material having high electron transportability as described above, and by suppressing the movement of electron carriers, it becomes possible to adjust the carrier balance. Such a configuration exhibits a great effect in suppressing problems (for example, reduction in device lifetime) caused by electrons passing through the light-emitting layer. Further, a layer for controlling the movement of electron carriers may be provided between the electron transport layer 118 and the light-emitting layer 130. The layer for controlling the movement of electron carriers is a layer in which a small amount of a substance having high electron trapping property is added to a material having high electron transportability as described above, and by suppressing the movement of electron carriers, it becomes possible to adjust the carrier balance. Such a configuration exhibits a great effect in suppressing problems (for example, reduction in device lifetime) caused by electrons passing through the light-emitting layer. Further, a layer for controlling the movement of electron carriers may be provided between the electron transport layer 118 and the light-emitting layer 130. The layer for controlling the movement of electron carriers is a layer in which a small amount of a substance having high electron trapping property is added to a material having high electron transportability as described above, and by suppressing the movement of electron carriers, it becomes possible to adjust the carrier balance. Such a configuration exhibits a great effect in suppressing problems (for example, reduction in device lifetime) caused by electrons passing through the light-emitting layer.

[0290] ≪Electron injection layer≫ The electron injection layer 119 has a function of promoting electron injection by reducing the electron injection barrier from the electrode 102, and for example, a Group 1 metal, a Group 2 metal, or their oxides, halides, carbonates, etc. can be used. Further, a composite material of the electron-transporting material shown above and a material showing electron-donating property can also be used. Examples of the material showing electron-donating property include The electron injection layer 119 has a function of promoting electron injection by reducing the electron injection barrier from the electrode 102, and for example, a Group 1 metal, a Group 2 metal, or their oxides, halides, carbonates, etc. can be used. Further, a composite material of the electron-transporting material shown above and a material showing electron-donating property can also be used. Examples of the material showing electron-donating property include The electron injection layer 119 has a function of promoting electron injection by reducing the electron injection barrier from the electrode 102, and for example, a Group 1 metal, a Group 2 metal, or their oxides, halides, carbonates, etc. can be used. Further, a composite material of the electron-transporting material shown above and a material showing electron-donating property can also be used. Examples of the material showing electron-donating property include The electron injection layer 119 has a function of promoting electron injection by reducing the electron injection barrier from the electrode 102, and for example, a Group 1 metal, a Group 2 metal, or their oxides, halides, carbonates, etc. can be used. Further, a composite material of the electron-transporting material shown above and a material showing electron-donating property can also be used. Examples of the material showing electron-donating property include Examples include Group 1 metals, Group 2 metals, or their oxides. Specifically include lithium fluoride (LiF), sodium fluoride (NaF), cesium fluoride (CsF ), calcium fluoride (CaF2), lithium oxide (LiO x ), etc., such as alkali metals , alkaline earth metals, or their compounds can be used. Also, rare earth metal compounds such as erbium fluoride (ErF3) can be used. Further, an electride may be used for the electron injection layer 119. Examples of the electride include substances obtained by adding electrons at a high concentration to a mixed oxide of calcium and aluminum. Also, a substance that can be used in the electron transport layer 118 may be used for the electron injection layer 119 . Moreover, a composite material formed by mixing an organic compound and an electron donor may be used for the electron injection layer 119 . Since electrons are generated in the organic compound by the electron donor, such a composite material has excellent electron injection properties and electron transport properties. In this case, the organic compound is preferably a material excellent in transporting the generated electrons. Specifically, for example, substances constituting the above-described

[0291] 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 preferable, and examples include lithium, cesium , magnesium, calcium, erbium, ytterbium, etc. Also, alkali metal oxides and alkaline earth metal oxides are preferable, and examples include lithium oxide, calcium oxide , barium oxide, etc. Further, a Lewis base such as magnesium oxide may be used . Specifically, alkali metals, alkaline earth metals, and rare earth metals are preferred, and examples include lithium, cesium , magnesium, calcium, erbium, ytterbium, etc. Also, alkali metal oxides and alkaline earth metal oxides are preferred, and examples include lithium oxide, calcium oxide , barium oxide, etc. Also, a Lewis base such as magnesium oxide may be used . It is also possible. In addition, organic compounds such as tetrathiafulvalene (abbreviation: TTF) can also be used. It is also possible.

[0292] Note that the above-mentioned light-emitting layer, hole injection layer, hole transport layer, electron transport layer, and electron injection layer can be formed by, respectively, vapor deposition methods (including vacuum vapor deposition), inkjet methods, coating methods, nozzle printing methods , gravure printing and other methods. In addition, for the above-mentioned light-emitting layer, hole injection layer , hole transport layer, electron transport layer, and electron injection layer, in addition to the above-mentioned materials, inorganic compounds such as quantum dots or polymer compounds (oligomers, dendrimers, polymers, etc.) may also be used.

[0293] Note that as the quantum dots, colloidal quantum dots, alloy-type quantum dots, core-shell type quantum dots, core-type quantum dots, etc. may be used. In addition, quantum dots containing element groups of Group 2 and Group 16, Group 13 and Group 15, Group 13 and Group 17, Group 11 and Group 17, or Group 14 and Group 15 may be used. Or, quantum dots having elements such as cadmium (Cd), selenium (Se), zinc (Zn ) sulfur (S), phosphorus (P), indium (In), tellurium (Te), lead (Pb), gallium (Ga), arsenic (As), aluminum (Al), etc. may also be used.

[0294] As the liquid medium used in the wet process, for example, 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, cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin, dodecane, dimethylformamide It is possible to use organic solvents such as N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). It is possible.

[0295] In addition, examples of polymer compounds that can be used in the light-emitting layer include poly[2-methoxy -5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (abbreviation: MEH -PPV), polyphenylene vinylene (PPV) derivatives such as 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-anth racene)], poly[(9,9-dihexylfluorenyl-2,7-diyl)-alt-( 2,5-dimethyl-1,4-phenylene)] and other polyfluorene derivatives, poly(3-hexyl thiophene-2,5-diyl) (abbreviation: P3HT) and other polyalkylthiophene (P AT) derivatives, polyphenylene derivatives, etc. Further, these polymer compounds and PVK, poly(2-vinylnaphthalene), poly[bis(4-phenyl)(2,4,6-tri methylphenyl)amine] (abbreviation: PTAA) and other polymer compounds may be doped with a light-emitting compound and used in the light-emitting layer. As the light-emitting compound, the light-emitting compounds mentioned above can be used. It is possible to use.

[0296] <<Substrate>> In addition, the light-emitting element according to one aspect of the present invention may be manufactured on a substrate made of glass, plastic, or the like. As for the order of manufacturing on the substrate, they may be laminated in order from the electrode 101 side, or may be laminated in order from the electrode 102 side.

[0297] Note that as the substrate on which the light-emitting element according to one aspect of the present invention can be formed, for example, glass, quartz, or plastic can be used. A flexible substrate may also be used. A flexible substrate refers to a substrate that can be bent (flexible), and examples thereof include plastic substrates made of polycarbonate, polyarylate, and the like. In addition, films, inorganic vapor deposition films, and the like can also be used. Note that as long as it functions as a support in the manufacturing process of the light-emitting element and the optical element, other materials may be used. Alternatively, as long as it has a function of protecting the light-emitting element and the optical element, it may be used.

[0298] For example, in this specification and the like, a light-emitting element can be formed using various substrates. The type of the substrate is not particularly limited. As an example of the substrate, a semiconductor substrate (for example, 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 a stainless steel foil, a tungsten substrate, a substrate having a tungsten foil, a flexible substrate, a laminated film, a cellulose nanofiber (CNF) containing a fibrous material, paper, or a base film, and the like. As an example of the glass substrate, there are barium borosilicate glass, aluminoborosilicate glass, or soda lime glass, and the like. Flexible substrates, laminated films, base films, and the like Examples include the following. For example, plastics such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), and polytetra fluoroethylene (PTFE). Or, as an example, resins such as acrylic. Or, as an example, polypropylene, polyester, polyvinyl fluoride, or polyvinyl chloride. Or, as an example, polyamide , polyimide, aramid, epoxy, inorganic vapor deposition film, or papers.

[0299] Also, a flexible substrate may be used as the substrate, and a light-emitting element may be formed directly on the flexible substrate. Or, a release layer may be provided between the substrate and the light-emitting element. The release layer is used to separate from the substrate after partially or completely completing the light-emitting element thereon and transfer it to another substrate. At that time, the light-emitting element can be transferred to a substrate with poor heat resistance or a flexible substrate. Incidentally, for the above-mentioned release layer, for example, a laminated structure of an inorganic film of a tungsten film and a silicon oxide film or a structure in which a resin film such as polyimide is formed on the substrate can be used. That is, a light-emitting element is formed using a certain substrate, and then the light-emitting element is transposed to another substrate, and the light-emitting element may be arranged on another substrate. Examples of the substrate to which the light-emitting element is transposed include, in addition to the substrates described above, cellophane substrate, stone substrate, wood substrate, cloth substrate (including natural fibers (silk, cotton,

[0300] hemp), synthetic fibers (nylon, polyurethane, polyester) or recycled fibers (acetate to, cupra, rayon, recycled polyester), etc.), leather substrate, or rubber substrate. By using these substrates, a light-emitting element that is not easily broken and a light-emitting element with high heat resistance can be obtained. ​​It can be a light - weight light - emitting element or a thin - type light - emitting element.

[0301] Further, for example, a field - effect transistor (FET) may be formed on the above - mentioned substrate, and a light - emitting element 150 may be fabricated on an electrode electrically connected to the FET. Thus, an active - matrix type display device for controlling the driving of the light - emitting element by the FET can be fabricated.

[0302] As described above, the configuration shown in this embodiment can be used in appropriate combination with other embodiments.

[0303] (Embodiment 2) In this embodiment, an example of a synthesis method of an organic compound that can be suitably used for a light - emitting element of an aspect of the present invention will be described by taking the organic compounds represented by general formulas (G1) and (G2) as examples.

[0304] >[Synthesis method of the organic compound represented by general formula (G1)] The organic compound represented by the above general formula (G1) can be synthesized by a synthesis method applying various reactions. For example, it can be synthesized by the following synthesis schemes (S - 1) and (S - 2). A diamine compound (compound 4) is obtained by coupling compound 1, arylamine (compound 2), and arylamine (compound 3).

[0305] Subsequently, the organic compound represented by the above general formula (G1) can be obtained by coupling the diamine compound (compound 4), aryl halide (compound 5), and aryl halide (compound 6).

[0306] [Chemical formula]

[0307] [Chemical formula]

[0308] In the above synthetic schemes (S-1) and (S-2), A represents a substituted or unsubstituted condensed aromatic ring having 10 to 30 carbon atoms or a substituted or unsubstituted condensed heteroaromatic ring having 10 to 30 carbon atoms, Ar to Ar 1 to Ar 4 each independently represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 13 carbon atoms, and X 1 to X 8 each independently represents any one of an alkyl group having 3 or more and 10 or less carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 or more and 10 or less carbon atoms, and a trialkylsilyl group having 3 or more and 12 or less carbon atoms. Examples of the condensed aromatic ring or condensed heteroaromatic ring include chrysene, phenanthrene, stilbene, acridone, phenoxazine, phenothiazine, etc. Particularly, anthracene, pyrene, coumarin, quinacridone, perylene, tetracene, naphthobisbenzofuran are preferable. In the above synthetic schemes (S-1) and (S-2), when performing the Buchwald-Hartwig reaction using a palladium catalyst, X to X represents a halogen group or a triflate group, and as the halogen, iodine, bromine, or chlorine is preferable. In this reaction,

[0309] palladium compounds such as bis(dibenzylideneacetone)palladium(0) and palladium(II) acetate, and tri(tert-butyl)phosphine, tri(n-hexyl)phosphine are used. 10 to X 13 represents a halogen group or a triflate group, and as the halogen, iodine, bromine, or chlorine is preferable. In this reaction, palladium compounds such as bis(dibenzylideneacetone)palladium(0) and palladium(II) acetate, and tri(tert-butyl)phosphine, tri(n-hexyl)phosphine are used. to X Triphenylphosphine, tricyclohexylphosphine, di(1-adamantyl)-n-butylphosphine, 2-dicyclohexylphosphino-2',6'-dimethoxy-1,1'-biphenyl and the like of ligands can be used. Also, organic bases such as sodium tert-butoxide and , inorganic bases such as potassium carbonate, cesium carbonate, sodium carbonate, etc. can be used. Also, as the solvent, toluene, xylene, mesitylene, benzene, tetrahydrofuran, dioxane and the like can be used. Note that the reagents that can be used in the reaction are not limited to these reagents.

[0310] Also, the reactions carried out in the above synthetic schemes (S-1) and (S-2) are not limited to the Buchwald-Hartwig reaction, and the Migita-Kosugi-Stille coupling reaction using an organotin compound, the coupling reaction using a Grignard reagent, the Ullmann reaction using copper or a copper compound and the like can be used.

[0311] In the above synthetic scheme (S-1), when compound 2 and compound 3 have different structures, it is preferable to first react compound 1 and compound 2 to form a coupling product, and then react the obtained coupling product with compound 3. When reacting compound 1 with compound 2 and compound 3 stepwise, compound 1 is preferably a dihalogenated compound, and X and X 10 and X 11 are preferably selectively subjected to amination reactions one by one using different halogens. This is preferred.

[0312] Furthermore, in the synthetic scheme (S-2), when compound 5 and compound 6 have different structures , first react Compound 4 and Compound 5 to obtain a coupling product, and then it is preferable to react the obtained coupling product with Compound 6.

[0313] (Embodiment 3) In this embodiment, a light-emitting element having a configuration different from that of the light-emitting element shown in Embodiment 1 will be described below with reference to FIG. 7. In FIG. 7, portions having the same functions as the reference numerals shown in FIG. 1(A) are shown with the same hatching pattern, and the reference numerals may be omitted . Also, portions having the same functions are denoted by the same reference numerals, and detailed descriptions thereof may be omitted in some cases.

[0314] <Configuration Example 2 of Light-Emitting Element> FIG. 7 is a schematic cross-sectional view of a light-emitting element 250. The light-emitting element 250 shown in FIG. 7 has a pair of electrodes (electrode 101 and electrode 102) with a plurality of light-emitting units (light-emitting unit 106 and light-emitting unit 108) therebetween. It is preferable that any one of the plurality of light-emitting units has the same configuration as the EL layer 100 shown in FIG. 1(A). That is, the light-emitting element 150 shown in FIG. 1 (A) has one light-emitting unit, and the light-emitting element 250 preferably has a plurality of light-emitting units. In the light-emitting element 250, although it will be described below assuming that electrode 101 functions as an anode and electrode 102 functions as a cathode, the configuration of the light-emitting element 25 0 may be reversed.

[0315] Also, in the light-emitting element 250 shown in FIG. 7, the light-emitting unit 106 and the light-emitting unit 108 are laminated, and a charge generation layer 1 15 is provided between the light-emitting unit 106 and the light-emitting unit 108. Note that the light-emitting unit 106 and the light-emitting unit 108 may have the same configuration or different Such a configuration may be used. For example, the light-emitting unit 108 may have the same configuration as the EL layer 100. This is preferable.

[0316] The light-emitting element 250 includes a light-emitting layer 120 and a light-emitting layer 170. The light-emitting unit 106 includes, in addition to the light-emitting layer 120, a hole injection layer 111, a hole transport layer 112, an electron transport layer 113, and an electron injection layer 114. The light-emitting unit 108 includes, in addition to the light-emitting layer 170, a hole injection layer 116, a hole transport layer 117, an electron transport layer 118, and an electron injection layer 11 9.

[0317] The light-emitting element 250 may contain a compound according to one aspect of the present invention in any of the layers included in the light-emitting unit 106 and the light-emitting unit 108. Preferably, the layer containing the compound is the light-emitting layer 120 or the light-emitting layer 170. Preferably, it is the light-emitting layer 120 or the light-emitting layer 170.

[0318] The charge generation layer 115 may have a configuration in which an acceptor substance, which is an electron acceptor, is added to a hole transporting material, or a configuration in which a donor substance, which is an electron donor, is added to an electron transporting material. Moreover, both of these configurations may be laminated. Moreover, both of these configurations may be laminated.

[0319] When the charge generation layer 115 contains a composite material of an organic compound and an acceptor substance, the composite material may be the same as the composite material that can be used for the hole injection layer 111 shown in Embodiment 1. As the organic compound, various compounds such as aromatic amine compounds, carbazole compounds, aromatic hydrocarbons, and polymer compounds (oligomers, dendrimers, polymers, etc.) can be used. As the organic compound, various compounds such as aromatic amine compounds, carbazole compounds, aromatic hydrocarbons, and polymer compounds (oligomers, dendrimers, polymers, etc.) can be used. As the organic compound, various compounds such as aromatic amine compounds, carbazole compounds, aromatic hydrocarbons, and polymer compounds (oligomers, dendrimers, polymers, etc.) can be used. In addition, as the organic compound, the hole mobility is 1×10 cm -6 cm 2 / Vs It is preferable to apply the above. However, substances with higher hole transportability than electrons may be used as long as they are other than these. The composite material of the organic compound and the acceptor substance is excellent in carrier injection property and carrier transport property, so low-voltage driving and low-current driving can be achieved. When the surface on the anode side of the light-emitting unit is in contact with the charge generation layer 115 the charge generation layer 115 can also serve as the hole injection layer or the hole transport layer of the light-emitting unit so that the light-emitting unit may be configured not to have a hole injection layer or a hole transport layer. Alternatively, when the surface on the cathode side of the light-emitting unit is in contact with the charge generation layer 115 the charge generation layer 115 can also serve as the electron injection layer or the electron transport layer of the light-emitting unit so that the light-emitting unit may be configured not to have an electron injection layer or an electron transport layer.

[0320] Note that the charge generation layer 115 may be formed as a laminated structure combining a layer containing a composite material of an organic compound and an acceptor substance and another layer formed of a material. For example, it may be formed by combining a layer containing a composite material of an organic compound and an acceptor substance and a layer containing one compound selected from electron-donating substances and a compound with high electron transportability. Also, it may be formed by combining a layer containing a composite material of an organic compound and an acceptor substance and a layer containing a transparent conductive film.

[0321] Note that the charge generation layer 115 sandwiched between the light-emitting unit 106 and the light-emitting unit 108 only needs to inject electrons into one light-emitting unit and holes into the other light-emitting unit when a voltage is applied between the electrode 101 and the electrode 102. For example, in FIG. 7, the electrode 1 ​​​​When a voltage is applied such that the potential of 01 is higher than the potential of the electrode 102, charge generation layer 115 injects electrons into the light-emitting unit 106 and holes into the light-emitting unit 108 .

[0322] Note that the charge generation layer 115 preferably has translucency with respect to visible light (specifically the transmittance of visible light with respect to the charge generation layer 115 is 40% or more) from the viewpoint of light extraction efficiency. Also, the charge generation layer 115 functions even if it has a lower conductivity than the pair of electrodes (electrode 101 and electrode 102).

[0323] By forming the charge generation layer 115 using the materials described above, an increase in the driving voltage in the case where the light-emitting layers are stacked can be suppressed.

[0324] Also, in FIG. 7, a light-emitting device having two light-emitting units has been described, but the same can be similarly applied to a light-emitting device in which three or more light-emitting units are stacked. . As shown in the light-emitting device 250, by arranging a plurality of light-emitting units between a pair of electrodes and partitioning them with a charge generation layer , high-brightness light emission can be enabled while keeping the current density low, and furthermore, a light-emitting device with a long lifespan can be realized. Also, a light-emitting device with low power consumption can be realized.

[0325] Note that in each of the above configurations, the light-emitting colors exhibited by the guest materials used in the light-emitting unit 106 and the light-emitting unit 108 may be the same or different from each other. When the guest materials have the function of emitting light of the same color as each other in the light-emitting unit 106 and the light-emitting unit 108 , the light-emitting device 250 becomes a light-emitting device that exhibits high light-emitting brightness with a small current value It is preferable. Further, when the guest materials included in the light-emitting unit 106 and the light-emitting unit 108 have functions of emitting lights of different colors, the light-emitting element 250 preferably becomes a multi-color light-emitting element. In this case, either one or both of the light-emitting layer 120 and the light-emitting layer 170 use a plurality of light-emitting materials having different emission wavelengths, so that the emission spectrum exhibited by the light-emitting element 250 is light obtained by synthesizing lights having different emission peaks, and thus the emission spectrum has at least two maxima. When the guest materials included in the light-emitting unit 106 and the light-emitting unit 108 have functions of emitting lights of different colors, the light-emitting element 250 preferably becomes a multi-color light-emitting element. In this case, either one or both of the light-emitting layer 120 and the light-emitting layer 170 use a plurality of light-emitting materials having different emission wavelengths, so that the emission spectrum exhibited by the light-emitting element 250 is light obtained by synthesizing lights having different emission peaks, and thus the emission spectrum has at least two maxima. In this case, either one or both of the light-emitting layer 120 and the light-emitting layer 170 use a plurality of light-emitting materials having different emission wavelengths, so that the emission spectrum exhibited by the light-emitting element 250 is light obtained by synthesizing lights having different emission peaks, and thus the emission spectrum has at least two maxima. In this case, either one or both of the light-emitting layer 120 and the light-emitting layer 170 use a plurality of light-emitting materials having different emission wavelengths, so that the emission spectrum exhibited by the light-emitting element 250 is light obtained by synthesizing lights having different emission peaks, and thus the emission spectrum has at least two maxima. In this case, either one or both of the light-emitting layer 120 and the light-emitting layer 170 use a plurality of light-emitting materials having different emission wavelengths, so that the emission spectrum exhibited by the light-emitting element 250 is light obtained by synthesizing lights having different emission peaks, and thus the emission spectrum has at least two maxima.

[0326] The above configuration is also suitable for obtaining white light. By making the lights of the light-emitting layer 120 and the light-emitting layer 170 be in a complementary color relationship with each other, white light can be obtained. In particular, it is preferable to select guest materials so as to obtain white light with high color rendering properties, or light having at least red, green, and blue. The above configuration is also suitable for obtaining white light. By making the lights of the light-emitting layer 120 and the light-emitting layer 170 be in a complementary color relationship with each other, white light can be obtained. In particular, it is preferable to select guest materials so as to obtain white light with high color rendering properties, or light having at least red, green, and blue. The above configuration is also suitable for obtaining white light. By making the lights of the light-emitting layer 120 and the light-emitting layer 170 be in a complementary color relationship with each other, white light can be obtained. In particular, it is preferable to select guest materials so as to obtain white light with high color rendering properties, or light having at least red, green, and blue. The above configuration is also suitable for obtaining white light. By making the lights of the light-emitting layer 120 and the light-emitting layer 170 be in a complementary color relationship with each other, white light can be obtained. In particular, it is preferable to select guest materials so as to obtain white light with high color rendering properties, or light having at least red, green, and blue.

[0327] It is preferable to use the configuration of the light-emitting layer 130 shown in Embodiment 1 for one or both of the light-emitting layer 120 and the light-emitting layer 170. By adopting this configuration, a light-emitting element with good luminous efficiency and reliability can be obtained. The guest material included in the light-emitting layer 130 is a fluorescent material. Therefore, by using the configuration of the light-emitting layer 130 shown in Embodiment 1 for one or both of the light-emitting layer 120 and the light-emitting layer 170, a light-emitting element with high efficiency and high reliability can be obtained. It is preferable to use the configuration of the light-emitting layer 130 shown in Embodiment 1 for one or both of the light-emitting layer 120 and the light-emitting layer 170. By adopting this configuration, a light-emitting element with good luminous efficiency and reliability can be obtained. The guest material included in the light-emitting layer 130 is a fluorescent material. Therefore, by using the configuration of the light-emitting layer 130 shown in Embodiment 1 for one or both of the light-emitting layer 120 and the light-emitting layer 170, a light-emitting element with high efficiency and high reliability can be obtained. It is preferable to use the configuration of the light-emitting layer 130 shown in Embodiment 1 for one or both of the light-emitting layer 120 and the light-emitting layer 170. By adopting this configuration, a light-emitting element with good luminous efficiency and reliability can be obtained. The guest material included in the light-emitting layer 130 is a fluorescent material. Therefore, by using the configuration of the light-emitting layer 130 shown in Embodiment 1 for one or both of the light-emitting layer 120 and the light-emitting layer 170, a light-emitting element with high efficiency and high reliability can be obtained. It is preferable to use the configuration of the light-emitting layer 130 shown in Embodiment 1 for one or both of the light-emitting layer 120 and the light-emitting layer 170. By adopting this configuration, a light-emitting element with good luminous efficiency and reliability can be obtained. The guest material included in the light-emitting layer 130 is a fluorescent material. Therefore, by using the configuration of the light-emitting layer 130 shown in Embodiment 1 for one or both of the light-emitting layer 120 and the light-emitting layer 170, a light-emitting element with high efficiency and high reliability can be obtained. It is preferable to use the configuration of the light-emitting layer 130 shown in Embodiment 1 for one or both of the light-emitting layer 120 and the light-emitting layer 170. By adopting this configuration, a light-emitting element with good luminous efficiency and reliability can be obtained. The guest material included in the light-emitting layer 130 is a fluorescent material. Therefore, by using the configuration of the light-emitting layer 130 shown in Embodiment 1 for one or both of the light-emitting layer 120 and the light-emitting layer 170, a light-emitting element with high efficiency and high reliability can be obtained.

[0328] Further, in the case of a light-emitting element in which three or more light-emitting units are stacked, the emission colors exhibited by the guest materials used in the respective light-emitting units may be the same or different from each other. When there are a plurality of light-emitting units exhibiting the same color light, the emission colors exhibited by the plurality of light-emitting units Further, in the case of a light-emitting element in which three or more light-emitting units are stacked, the emission colors exhibited by the guest materials used in the respective light-emitting units may be the same or different from each other. When there are a plurality of light-emitting units exhibiting the same color light, the emission colors exhibited by the plurality of light-emitting units Further, in the case of a light-emitting element in which three or more light-emitting units are stacked, the emission colors exhibited by the guest materials used in the respective light-emitting units may be the same or different from each other. When there are a plurality of light-emitting units exhibiting the same color light, the emission colors exhibited by the plurality of light-emitting units A high emission luminance can be obtained with a small current value as compared with other colors. Such a configuration can be suitably used for adjusting the emission color. In particular, it is suitable when using guest materials having different emission efficiencies and exhibiting different emission colors. For example, when having a three-layer emission unit, two layers of emission units having a fluorescent material of the same color and one layer of an emission unit having a phosphorescent material exhibiting an emission color different from that of the fluorescent material are provided, so that the emission intensities of fluorescence and phosphorescence can be adjusted. That is, the intensity of the emission color can be adjusted by the number of emission units. In the case of such a light-emitting device having two layers of such fluorescence emission units and one layer of phosphorescence emission units, a light-emitting device containing two layers of emission units containing a blue fluorescent material and one layer of an emission unit containing a yellow phosphorescent material, a light-emitting device having two layers of emission units containing a blue fluorescent material and one layer of an emission unit containing a red phosphorescent material and a green phosphorescent material, or a light-emitting device having two layers of emission units containing a blue fluorescent material and one layer of an emission unit containing a red phosphorescent material, a yellow phosphorescent material and a green phosphorescent material is preferable because white light emission can be efficiently obtained. Thus, the light-emitting device according to one aspect of the present invention can be appropriately combined with a phosphorescent emission unit. Further, at least one of the light-emitting layer 120 or the light-emitting layer 170 may be further divided into layers, and different light-emitting materials may be contained in each of the divided layers. That is, at least one of the light-emitting layer 120 or the light-emitting layer 170 may be composed of two or more layers. For example, a first light-emitting layer and a second light-emitting layer may be laminated in order from the hole transport layer side to form a light-emitting layer. Compared with other colors, a high emission luminance can be obtained with a small current value. Such a configuration can be suitably used for adjusting the emission color. In particular, it is suitable when using guest materials having different emission efficiencies and exhibiting different emission colors. For example, when having a three-layer emission unit, two layers of emission units having a fluorescent material of the same color and one layer of an emission unit having a phosphorescent material exhibiting an emission color different from that of the fluorescent material are provided, so that the emission intensities of fluorescence and phosphorescence can be adjusted. That is, the intensity of the emission color can be adjusted by the number of emission units. In the case of such a light-emitting device having two layers of such fluorescence emission units and one layer of phosphorescence emission units, a light-emitting device containing two layers of emission units containing a blue fluorescent material and one layer of an emission unit containing a yellow phosphorescent material, a light-emitting device having two layers of emission units containing a blue fluorescent material and one layer of an emission unit containing a red phosphorescent material and a green phosphorescent material, or a light-emitting device having two layers of emission units containing a blue fluorescent material and one layer of an emission unit containing a red phosphorescent material, a yellow phosphorescent material and a green phosphorescent material is preferable because white light emission can be efficiently obtained. Thus, the light-emitting device according to one aspect of the present invention can be appropriately combined with a phosphorescent emission unit. Further, at least one of the light-emitting layer 120 or the light-emitting layer 170 may be further divided into layers, and different light-emitting materials may be contained in each of the divided layers. That is, at least one of the light-emitting layer 120 or the light-emitting layer 170 may be composed of two or more layers. For example, a first light-emitting layer and a second light-emitting layer may be laminated in order from the hole transport layer side to form a light-emitting layer. Compared with other colors, a high emission luminance can be obtained with a small current value. Such a configuration can be suitably used for adjusting the emission color. In particular, it is suitable when using guest materials having different emission efficiencies and exhibiting different emission colors. For example, when having a three-layer emission unit, two layers of emission units having a fluorescent material of the same color and one layer of an emission unit having a phosphorescent material exhibiting an emission color different from that of the fluorescent material are provided, so that the emission intensities of fluorescence and phosphorescence can be adjusted. That is, the intensity of the emission color can be adjusted by the number of emission units.

[0329] In the case of such a light-emitting device having two layers of such fluorescence emission units and one layer of phosphorescence emission units, a light-emitting device containing two layers of emission units containing a blue fluorescent material and one layer of an emission unit containing a yellow phosphorescent material, a light-emitting device having two layers of emission units containing a blue fluorescent material and one layer of an emission unit containing a red phosphorescent material and a green phosphorescent material, or a light-emitting device having two layers of emission units containing a blue fluorescent material and one layer of an emission unit containing a red phosphorescent material, a yellow phosphorescent material and a green phosphorescent material is preferable because white light emission can be efficiently obtained. Thus, the light-emitting device according to one aspect of the present invention can be appropriately combined with a phosphorescent emission unit. Further, at least one of the light-emitting layer 120 or the light-emitting layer 170 may be further divided into layers, and different light-emitting materials may be contained in each of the divided layers. That is, at least one of the light-emitting layer 120 or the light-emitting layer 170 may be composed of two or more layers. For example, a first light-emitting layer and a second light-emitting layer may be laminated in order from the hole transport layer side to form a light-emitting layer. Compared with other colors, a high emission luminance can be obtained with a small current value. Such a configuration can be suitably used for adjusting the emission color. In particular, it is suitable when using guest materials having different emission efficiencies and exhibiting different emission colors. For example, when having a three-layer emission unit, two layers of emission units having a fluorescent material of the same color and one layer of an emission unit having a phosphorescent material exhibiting an emission color different from that of the fluorescent material are provided, so that the emission intensities of fluorescence and phosphorescence can be adjusted. That is, the intensity of the emission color can be adjusted by the number of emission units. In the case of such a light-emitting device having two layers of such fluorescence emission units and one layer of phosphorescence emission units, a light-emitting device containing two layers of emission units containing a blue fluorescent material and one layer of an emission unit containing a yellow phosphorescent material, a light-emitting device having two layers of emission units containing a blue fluorescent material and one layer of an emission unit containing a red phosphorescent material and a green phosphorescent material, or a light-emitting device having two layers of emission units containing a blue fluorescent material and one layer of an emission unit containing a red phosphorescent material, a yellow phosphorescent material and a green phosphorescent material is preferable because white light emission can be efficiently obtained. Thus, the light-emitting device according to one aspect of the present invention can be appropriately combined with a phosphorescent emission unit. Further, at least one of the light-emitting layer 120 or the light-emitting layer 170 may be further divided into layers, and different light-emitting materials may be contained in each of the divided layers. That is, at least one of the light-emitting layer 120 or the light-emitting layer 170 may be composed of two or more layers. For example, a first light-emitting layer and a second light-emitting layer may be laminated in order from the hole transport layer side to form a light-emitting layer. Compared with other colors, a high emission luminance can be obtained with a small current value. Such a configuration can be suitably used for adjusting the emission color. In particular, it is suitable when using guest materials having different emission efficiencies and exhibiting different emission colors. For example, when having a three-layer emission unit, two layers of emission units having a fluorescent material of the same color and one layer of an emission unit having a phosphorescent material exhibiting an emission color different from that of the fluorescent material are provided, so that the emission intensities of fluorescence and phosphorescence can be adjusted. That is, the intensity of the emission color can be adjusted by the number of emission units. In the case of such a light-emitting device having two layers of such fluorescence emission units and one layer of phosphorescence emission units, a light-emitting device containing two layers of emission units containing a blue fluorescent material and one layer of an emission unit containing a yellow phosphorescent material, a light-emitting device having two layers of emission units containing a blue fluorescent material and one layer of an emission unit containing a red phosphorescent material and a green phosphorescent material, or a light-emitting device having two layers of emission units containing a blue fluorescent material and one layer of an emission unit containing a red phosphorescent material, a yellow phosphorescent material and a green phosphorescent material is preferable because white light emission can be efficiently obtained. Thus, the light-emitting device according to one aspect of the present invention can be appropriately combined with a phosphorescent emission unit.

[0330] Further, at least one of the light-emitting layer 120 or the light-emitting layer 170 may be further divided into layers, and different light-emitting materials may be contained in each of the divided layers. That is, at least one of the light-emitting layer 120 or the light-emitting layer 170 may be composed of two or more layers. For example, a first light-emitting layer and a second light-emitting layer may be laminated in order from the hole transport layer side to form a light-emitting layer. Compared with other colors, a high emission luminance can be obtained with a small current value. Such a configuration can be suitably used for adjusting the emission color. In particular, it is suitable when using guest materials having different emission efficiencies and exhibiting different emission colors. For example, when having a three-layer emission unit, two layers of emission units having a fluorescent material of the same color and one layer of an emission unit having a phosphorescent material exhibiting an emission color different from that of the fluorescent material are provided, so that the emission intensities of fluorescence and phosphorescence can be adjusted. That is, the intensity of the emission color can be adjusted by the number of emission units. In the case of such a light-emitting device having two layers of such fluorescence emission units and one layer of phosphorescence emission units, a light-emitting device containing two layers of emission units containing a blue fluorescent material and one layer of an emission unit containing a yellow phosphorescent material, a light-emitting device having two layers of emission units containing a blue fluorescent material and one layer of an emission unit containing a red phosphorescent material and a green phosphorescent material, or a light-emitting device having two layers of emission units containing a blue fluorescent material and one layer of an emission unit containing a red phosphorescent material, a yellow phosphorescent material and a green phosphorescent material is preferable because white light emission can be efficiently obtained. Thus, the light-emitting device according to one aspect of the present invention can be appropriately combined with a phosphorescent emission unit. Further, at least one of the light-emitting layer 120 or the light-emitting layer 170 may be further divided into layers, and different light-emitting materials may be contained in each of the divided layers. That is, at least one of the light-emitting layer 120 or the light-emitting layer 170 may be composed of two or more layers. For example, a first light-emitting layer and a second light-emitting layer may be laminated in order from the hole transport layer side to form a light-emitting layer. When this is the case, a material having hole transporting properties is used as the host material of the first light-emitting layer, and the second light-emitting layer has a configuration in which a material having electron transporting properties is used as the host material. In this case, the light-emitting materials of the first light-emitting layer and the second light-emitting layer may be the same material or different materials, and may be materials having a function of emitting light of the same color or materials having a function of emitting light of different colors. By having a configuration including a plurality of light-emitting materials having functions of emitting light of different colors, it is possible to obtain white light emission with high color rendering properties composed of three primary colors or four or more light-emitting colors.

[0331] Note that this embodiment can be appropriately combined with other embodiments.

[0332] (Embodiment 4) In this embodiment, a light-emitting device using the light-emitting element described in Embodiment 1 and Embodiment 3 will be described with reference to FIGS. 8(A) and 8(B).

[0333] FIG. 8(A) is a top view showing the light-emitting device, and FIG. 8(B) is a cross-sectional view obtained by cutting FIG. 8(A) along A-B and C-D. This light-emitting device includes a drive circuit unit (source-side drive circuit) 601, a pixel unit 602, and a drive circuit unit (gate-side drive circuit) 603, which are indicated by dotted lines as units for controlling the light emission of the light-emitting element. Further, 604 is a sealing substrate, 625 is a drying material, 605 is a sealing material, and the inside surrounded by the sealing material 605 is a space 607.

[0334] Note that the routing wiring 608 is a wiring for transmitting signals input to the source-side drive circuit 601 and the gate-side drive circuit 603, and is an FPC (flexible printed circuit) serving as an external input terminal. receives a video signal, a clock signal, a start signal, a reset signal, etc. from the input circuit 609. Although only the FPC is illustrated here, a printed wiring board (PWB) may be attached to this FPC. The light-emitting device in this specification includes not only the light-emitting device body but also a state in which an FPC or a PWB is attached thereto. Next, the cross-sectional structure of the above-described light-emitting device will be described with reference to FIG. 8(B). A drive circuit portion and a pixel portion are formed on the element substrate 610. Here, one pixel in the source-side drive circuit 601, which is the drive circuit portion, and the pixel portion 602 is shown. The source-side drive circuit 601 is formed of a CMOS circuit combined with an n-channel type TFT 623 and a p-channel type TFT 624. The drive circuit may be formed of various CMOS circuits, PMOS circuits, or NMOS circuits. In this embodiment, a driver integrated type in which the drive circuit is formed on the substrate is shown, but this is not necessarily required, and the drive circuit may be formed outside the substrate. The pixel portion 602 is formed of pixels each including a switching TFT 611, a current control TFT 612, and a first electrode 613 electrically connected to the drain thereof. An insulator 614 is formed so as to cover an end portion of the first electrode 613. The insulator 614 can be formed by using a positive photosensitive resin film. In order to improve the covering property of the film formed on the insulator 614,

[0335]

[0336]

[0337]

[0338] A surface having a curvature is formed at the upper end or the lower end. 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. Further, as the insulator 614, either a negative type or a positive type photosensitive material can be used. When photosensitive acrylic is used as the material, 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. Also, as the insulator 614, either a negative type or a positive type photosensitive material can be used. A surface having a curvature is formed at the upper end or the lower end. 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. Further, as the insulator 614, either a negative type or a positive type photosensitive material can be used.

[0339] An EL layer 616 and a second electrode 617 are respectively formed on the first electrode 613. Here, as the material used for the first electrode 613 that functions as an anode, it is desirable to use a material having a large work function. For example, an ITO film, an indium tin oxide film containing silicon, an indium oxide film containing 2 wt% or more and 20 wt% or less of zinc oxide, a titanium nitride film, a chromium film, a tungsten film, a Zn film, a Pt film, etc., in addition to single-layer films, a laminate of a titanium nitride film and a film mainly composed of aluminum, a three-layer structure of a titanium nitride film, a film mainly composed of aluminum, and a titanium nitride film can be used. Note that when a laminated structure is used, the resistance as wiring is low, good ohmic contact can be achieved, and it can further function as an anode. An EL layer 616 and a second electrode 617 are respectively formed on the first electrode 613. Here, as the material used for the first electrode 613 that functions as an anode, it is desirable to use a material having a large work function. For example, an ITO film, an indium tin oxide film containing silicon, an indium oxide film containing 2 wt% or more and 20 wt% or less of zinc oxide, a titanium nitride film, a chromium film, a tungsten film, a Zn film, a Pt film, etc., in addition to single-layer films, a laminate of a titanium nitride film and a film mainly composed of aluminum, a three-layer structure of a titanium nitride film, a film mainly composed of aluminum, and a titanium nitride film can be used. Note that when a laminated structure is used, the resistance as wiring is low, good ohmic contact can be achieved, and it can further function as an anode. An EL layer 616 and a second electrode 617 are respectively formed on the first electrode 613. Here, as the material used for the first electrode 613 that functions as an anode, it is desirable to use a material having a large work function. For example, an ITO film, an indium tin oxide film containing silicon, an indium oxide film containing 2 wt% or more and 20 wt% or less of zinc oxide, a titanium nitride film, a chromium film, a tungsten film, a Zn film, a Pt film, etc., in addition to single-layer films, a laminate of a titanium nitride film and a film mainly composed of aluminum, a three-layer structure of a titanium nitride film, a film mainly composed of aluminum, and a titanium nitride film can be used. Note that when a laminated structure is used, the resistance as wiring is low, good ohmic contact can be achieved, and it can further function as an anode. An EL layer 616 and a second electrode 617 are respectively formed on the first electrode 613. Here, as the material used for the first electrode 613 that functions as an anode, it is desirable to use a material having a large work function. For example, an ITO film, an indium tin oxide film containing silicon, an indium oxide film containing 2 wt% or more and 20 wt% or less of zinc oxide, a titanium nitride film, a chromium film, a tungsten film, a Zn film, a Pt film, etc., in addition to single-layer films, a laminate of a titanium nitride film and a film mainly composed of aluminum, a three-layer structure of a titanium nitride film, a film mainly composed of aluminum, and a titanium nitride film can be used. Note that when a laminated structure is used, the resistance as wiring is low, good ohmic contact can be achieved, and it can further function as an anode. An EL layer 616 and a second electrode 617 are respectively formed on the first electrode 613. Here, as the material used for the first electrode 613 that functions as an anode, it is desirable to use a material having a large work function. For example, an ITO film, an indium tin oxide film containing silicon, an indium oxide film containing 2 wt% or more and 20 wt% or less of zinc oxide, a titanium nitride film, a chromium film, a tungsten film, a Zn film, a Pt film, etc., in addition to single-layer films, a laminate of a titanium nitride film and a film mainly composed of aluminum, a three-layer structure of a titanium nitride film, a film mainly composed of aluminum, and a titanium nitride film can be used. Note that when a laminated structure is used, the resistance as wiring is low, good ohmic contact can be achieved, and it can further function as an anode. An EL layer 616 and a second electrode 617 are respectively formed on the first electrode 613. Here, as the material used for the first electrode 613 that functions as an anode, it is desirable to use a material having a large work function. For example, an ITO film, an indium tin oxide film containing silicon, an indium oxide film containing 2 wt% or more and 20 wt% or less of zinc oxide, a titanium nitride film, a chromium film, a tungsten film, a Zn film, a Pt film, etc., in addition to single-layer films, a laminate of a titanium nitride film and a film mainly composed of aluminum, a three-layer structure of a titanium nitride film, a film mainly composed of aluminum, and a titanium nitride film can be used. Note that when a laminated structure is used, the resistance as wiring is low, good ohmic contact can be achieved, and it can further function as an anode. An EL layer 616 and a second electrode 617 are respectively formed on the first electrode 613. Here, as the material used for the first electrode 613 that functions as an anode, it is desirable to use a material having a large work function. For example, an ITO film, an indium tin oxide film containing silicon, an indium oxide film containing 2 wt% or more and 20 wt% or less of zinc oxide, a titanium nitride film, a chromium film, a tungsten film, a Zn film, a Pt film, etc., in addition to single-layer films, a laminate of a titanium nitride film and a film mainly composed of aluminum, a three-layer structure of a titanium nitride film, a film mainly composed of aluminum, and a titanium nitride film can be used. Note that when a laminated structure is used, the resistance as wiring is low, good ohmic contact can be achieved, and it can further function as an anode. An EL layer 616 and a second electrode 617 are respectively formed on the first electrode 613. Here, as the material used for the first electrode 613 that functions as an anode, it is desirable to use a material having a large work function. For example, an ITO film, an indium tin oxide film containing silicon, an indium oxide film containing 2 wt% or more and 20 wt% or less of zinc oxide, a titanium nitride film, a chromium film, a tungsten film, a Zn film, a Pt film, etc., in addition to single-layer films, a laminate of a titanium nitride film and a film mainly composed of aluminum, a three-layer structure of a titanium nitride film, a film mainly composed of aluminum, and a titanium nitride film can be used. Note that when a laminated structure is used, the resistance as wiring is low, good ohmic contact can be achieved, and it can further function as an anode. An EL layer 616 and a second electrode 617 are respectively formed on the first electrode 613. Here, as the material used for the first electrode 613 that functions as an anode, it is desirable to use a material having a large work function. For example, an ITO film, an indium tin oxide film containing silicon, an indium oxide film containing 2 wt% or more and 20 wt% or less of zinc oxide, a titanium nitride film, a chromium film, a tungsten film, a Zn film, a Pt film, etc., in addition to single-layer films, a laminate of a titanium nitride film and a film mainly composed of aluminum, a three-layer structure of a titanium nitride film, a film mainly composed of aluminum, and a titanium nitride film can be used. Note that when a laminated structure is used, the resistance as wiring is low, good ohmic contact can be achieved, and it can further function as an anode.

[0340] Also, the EL layer 616 is formed by various methods such as a vapor deposition method using a vapor deposition mask, an inkjet method, and a spin coating method. The material constituting the EL layer 616 may be a low molecular compound or a high molecular compound (including oligomers and dendrimers). Also, the EL layer 616 is formed by various methods such as a vapor deposition method using a vapor deposition mask, an inkjet method, and a spin coating method. The material constituting the EL layer 616 may be a low molecular compound or a high molecular compound (including oligomers and dendrimers). Also, the EL layer 616 is formed by various methods such as a vapor deposition method using a vapor deposition mask, an inkjet method, and a spin coating method. The material constituting the EL layer 616 may be a low molecular compound or a high molecular compound (including oligomers and dendrimers).

[0341] Furthermore, the material used for the second electrode 617 that is formed on the EL layer 616 and functions as a cathode is a material having a small work function (Al, Mg, Li, Ca, or their alloys or compounds Furthermore, the material used for the second electrode 617 that is formed on the EL layer 616 and functions as a cathode is a material having a small work function (Al, Mg, Li, Ca, or their alloys or compounds It is preferable to use substances such as MgAg, MgIn, and AlLi. When the light generated in the EL layer 616 passes through the second electrode 617, as the second electrode 617, a metal thin film with a reduced thickness and a transparent conductive film (ITO, indium oxide containing 2 wt% or more and 20 wt% or less of zinc oxide, indium tin oxide containing silicon, zinc oxide (ZnO), etc.) are preferably used in combination. When the generated light passes through the second electrode 617, as the second electrode 617, a metal thin film with a reduced thickness and a transparent conductive film (ITO, indium oxide containing 2 wt% or more and 20 wt% or less of zinc oxide, indium tin oxide containing silicon, zinc oxide (ZnO), etc.) are preferably used in combination. When the generated light passes through the second electrode 617, as the second electrode 617, a metal thin film with a reduced thickness and a transparent conductive film (ITO, indium oxide containing 2 wt% or more and 20 wt% or less of zinc oxide, indium tin oxide containing silicon, zinc oxide (ZnO), etc.) are preferably used in combination. When the generated light passes through the second electrode 617, as the second electrode 617, a metal thin film with a reduced thickness and a transparent conductive film (ITO, indium oxide containing 2 wt% or more and 20 wt% or less of zinc oxide, indium tin oxide containing silicon, zinc oxide (ZnO), etc.) are preferably used in combination. When the generated light passes through the second electrode 617, as the second electrode 617, a metal thin film with a reduced thickness and a transparent conductive film (ITO, indium oxide containing 2 wt% or more and 20 wt% or less of zinc oxide, indium tin oxide containing silicon, zinc oxide (ZnO), etc.) are preferably used in combination.

[0342] Note that the light-emitting element 618 is formed by the first electrode 613, the EL layer 616, and the second electrode 617. The light-emitting element 618 preferably has the configuration of the first embodiment and the second embodiment. Note that although a plurality of light-emitting elements are formed in the pixel portion, in the light-emitting device of the present embodiment, both light-emitting elements having the configuration described in the first embodiment and the second embodiment and light-emitting elements having other configurations may be included. Note that the light-emitting element 618 is formed by the first electrode 613, the EL layer 616, and the second electrode 617. The light-emitting element 618 preferably has the configuration of the first embodiment and the second embodiment. Note that although a plurality of light-emitting elements are formed in the pixel portion, in the light-emitting device of the present embodiment, both light-emitting elements having the configuration described in the first embodiment and the second embodiment and light-emitting elements having other configurations may be included. Note that the light-emitting element 618 is formed by the first electrode 613, the EL layer 616, and the second electrode 617. The light-emitting element 618 preferably has the configuration of the first embodiment and the second embodiment. Note that although a plurality of light-emitting elements are formed in the pixel portion, in the light-emitting device of the present embodiment, both light-emitting elements having the configuration described in the first embodiment and the second embodiment and light-emitting elements having other configurations may be included. Note that the light-emitting element 618 is formed by the first electrode 613, the EL layer 616, and the second electrode 617. The light-emitting element 618 preferably has the configuration of the first embodiment and the second embodiment. Note that although a plurality of light-emitting elements are formed in the pixel portion, in the light-emitting device of the present embodiment, both light-emitting elements having the configuration described in the first embodiment and the second embodiment and light-emitting elements having other configurations may be included. Note that the light-emitting element 618 is formed by the first electrode 613, the EL layer 616, and the second electrode 617. The light-emitting element 618 preferably has the configuration of the first embodiment and the second embodiment. Note that although a plurality of light-emitting elements are formed in the pixel portion, in the light-emitting device of the present embodiment, both light-emitting elements having the configuration described in the first embodiment and the second embodiment and light-emitting elements having other configurations may be included.

[0343] Furthermore, by bonding the sealing substrate 604 to the element substrate 610 with the sealing material 605, a structure is formed in which the light-emitting element 618 is provided in the space 607 surrounded by the element substrate 610, the sealing substrate 604, and the sealing material 605. Note that the space 607 is filled with a filling material, and in addition to the case where an inert gas (such as nitrogen or argon) is filled, it may be filled with a resin or a drying material or both. Furthermore, by bonding the sealing substrate 604 to the element substrate 610 with the sealing material 605, a structure is formed in which the light-emitting element 618 is provided in the space 607 surrounded by the element substrate 610, the sealing substrate 604, and the sealing material 605. Note that the space 607 is filled with a filling material, and in addition to the case where an inert gas (such as nitrogen or argon) is filled, it may be filled with a resin or a drying material or both. Furthermore, by bonding the sealing substrate 604 to the element substrate 610 with the sealing material 605, a structure is formed in which the light-emitting element 618 is provided in the space 607 surrounded by the element substrate 610, the sealing substrate 604, and the sealing material 605. Note that the space 607 is filled with a filling material, and in addition to the case where an inert gas (such as nitrogen or argon) is filled, it may be filled with a resin or a drying material or both. Furthermore, by bonding the sealing substrate 604 to the element substrate 610 with the sealing material 605, a structure is formed in which the light-emitting element 618 is provided in the space 607 surrounded by the element substrate 610, the sealing substrate 604, and the sealing material 605. Note that the space 607 is filled with a filling material, and in addition to the case where an inert gas (such as nitrogen or argon) is filled, it may be filled with a resin or a drying material or both. Furthermore, by bonding the sealing substrate 604 to the element substrate 610 with the sealing material 605, a structure is formed in which the light-emitting element 618 is provided in the space 607 surrounded by the element substrate 610, the sealing substrate 604, and the sealing material 605. Note that the space 607 is filled with a filling material, and in addition to the case where an inert gas (such as nitrogen or argon) is filled, it may be filled with a resin or a drying material or both.

[0344] Note that it is preferable to use an epoxy resin or glass frit for the sealing material 605. Also, these materials are desirably materials that do not transmit moisture and oxygen as much as possible. Also, as the material used for the sealing substrate 604, in addition to a glass substrate or a quartz substrate, FRP (Fiber R Note that it is preferable to use an epoxy resin or glass frit for the sealing material 605. Also, these materials are desirably materials that do not transmit moisture and oxygen as much as possible. Also, as the material used for the sealing substrate 604, in addition to a glass substrate or a quartz substrate, FRP (Fiber R Note that it is preferable to use an epoxy resin or glass frit for the sealing material 605. Also, these materials are desirably materials that do not transmit moisture and oxygen as much as possible. Also, as the material used for the sealing substrate 604, in addition to a glass substrate or a quartz substrate, FRP (Fiber R reinforced Plastics), PVF (polyvinyl fluoride), polyester or acrylic, etc. A plastic substrate made of such materials can be used.

[0345] As described above, a light-emitting device using the light-emitting elements described in Embodiment 1 and Embodiment 3 can be obtained.

[0346] <Configuration Example 1 of Light-Emitting Device> In FIG. 9, as an exampl...

Claims

1. A light-emitting element having one light-emitting layer between a pair of electrodes, the light-emitting layer includes a first material that exhibits delayed fluorescence and a second material that has a function of converting singlet excitation energy into light emission, the second material comprises a luminophore and five or more protecting groups; the luminophore is a fused aromatic ring or a fused heteroaromatic ring; the five or more protecting groups each independently include 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, and a trialkylsilyl group having from 3 to 12 carbon atoms; A light-emitting device, wherein an emission spectrum of the first material overlaps with an absorption band on the longest wavelength side of an absorption spectrum of the second material.

2. In claim 1, a light-emitting element, wherein 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.

3. A light-emitting element having one light-emitting layer between a pair of electrodes, the light-emitting layer includes a first material that exhibits delayed fluorescence and a second material that has a function of converting singlet excitation energy into light emission, the second material comprises a luminophore and at least four protecting groups; the luminophore is a fused aromatic ring or a fused heteroaromatic ring; the four protecting groups are not directly bonded to the fused aromatic ring or the fused heteroaromatic ring, the four protecting groups each independently have 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, and a trialkylsilyl group having from 3 to 12 carbon atoms; A light-emitting device, wherein an emission spectrum of the first material overlaps with an absorption band on the longest wavelength side of an absorption spectrum of the second material.

4. In claim 2 or 3, The alkyl group having 3 to 10 carbon atoms is a branched alkyl group.

5. In claim 4, The branched alkyl group has a quaternary carbon.

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

7. In any one of claims 1 to 6, A light-emitting element, wherein the concentration of the second material in the light-emitting layer is 0.01 wt % or more and 2 wt % or less.

8. A light emitting element according to any one of claims 1 to 7, and at least one of a color filter and a transistor.

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

10. A lighting device comprising: the light-emitting element according to claim 1 ; and a housing.

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