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

Abstract

To provide a light-emitting element with high luminous efficiency.SOLUTION: A light-emitting element includes a first organic compound, a second organic compound, and a guest material. The LUMO level of the first organic compound is lower than the LUMO level of the second organic compound, and the HOMO level of the first organic compound is lower than the HOMO level of the second organic compound. The LUMO level of the guest material is lower than the LUMO level of the first organic compound, and the HOMO level of the guest material is lower than the HOMO level of the second organic compound. The energy difference between the LUMO level and the HOMO level of the guest material is larger than the energy difference between the LUMO level of the first organic compound and the HOMO level of the second organic compound. The guest material has a function of converting triplet excited energy into light emission. The combination of the first organic compound and the second organic compound forms an exciplex.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] One aspect of the present invention relates to a light-emitting element, or a display device, an electronic device, 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 material is sandwiched between a pair of electrodes. By applying a voltage between the electrodes of this element, light emission from the light-emitting material 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 material is sandwiched between a pair of electrodes. By applying a voltage between the electrodes of this element, light emission from the light-emitting material 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 material is sandwiched between a pair of electrodes. By applying a voltage between the electrodes of this element, light emission from the light-emitting material 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 material is sandwiched between a pair of electrodes. By applying a voltage between the electrodes of this element, light emission from the light-emitting material 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] A light-emitting element using an organic material as a light-emitting material and provided with an EL layer containing the light-emitting material between a pair of electrodes. In the case of a device (e.g., an organic EL device), by applying a voltage 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, when the injected electrons and holes recombine, the light-emitting organic material is excited to an excited state, and light can be obtained from the excited light-emitting organic material.

[0006] As the types of excited states formed by the organic material, there are a singlet excited state (S * ) and a triplet excited state (T ). The light emission from the singlet excited state is called fluorescence, and the light emission from the triplet excited state is called phosphorescence. * Also, their statistical generation ratio in the light-emitting device is S * :T * = 1 :3. Therefore, a light-emitting device using a material that emits phosphorescence (phosphorescent material) can obtain higher luminous efficiency than a light-emitting device using a material that emits fluorescence (fluorescent material). Therefore, in recent years, the development of light-emitting devices using phosphorescent materials capable of converting the energy of the triplet excited state into light emission has been actively carried out (see, for example, Patent Document 1).

[0007] The energy required to excite the organic material depends on the energy difference between the LUMO level and the HOMO level of the organic material, and this energy difference generally corresponds to the energy of the singlet excited state. In a light-emitting device using an organic material that emits phosphorescence, the triplet excitation energy is converted into the energy of light emission. Therefore, when the energy difference between the singlet excited state and the triplet excited state formed by the organic material is large, the energy required to excite the organic material becomes higher than the energy of light emission by an amount corresponding to this energy difference. Organic The difference between the energy required to excite the material and the energy of the light emission affects the device characteristics as an increase in the driving voltage in the light-emitting device, and a method for suppressing such an increase in the driving voltage is being developed (see Patent Document 2). Among light-emitting devices using a phosphorescent material, particularly in a light-emitting device that exhibits blue light emission, it is difficult to develop a stable compound having a high triplet excitation energy level, and thus it has not yet been put into practical use. Therefore, development of a phosphorescent material having high luminous efficiency and stability is demanded. Also, development of a phosphorescent light-emitting device having high luminous efficiency and excellent reliability is demanded.

[0008] Among light-emitting devices using a phosphorescent material, particularly in a light-emitting device that exhibits blue light emission, since it is difficult to develop a stable compound having a high triplet excitation energy level, it has not yet been put into practical use. Therefore, development of a phosphorescent material having high luminous efficiency and stability is demanded. Also, development of a phosphorescent light-emitting device having high luminous efficiency and excellent reliability is demanded. Among light-emitting devices using a phosphorescent material, particularly in a light-emitting device that exhibits blue light emission, since it is difficult to develop a stable compound having a high triplet excitation energy level, it has not yet been put into practical use. Therefore, development of a phosphorescent material having high luminous efficiency and stability is demanded. Also, development of a phosphorescent light-emitting device having high luminous efficiency and excellent reliability is demanded.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0010] Iridium complexes are known as phosphorescent materials that exhibit high luminous efficiency. Also, iridium complexes having a pyridine skeleton or a nitrogen-containing five-membered heterocyclic skeleton as a ligand are known as iridium complexes having high emission energy. The pyridine skeleton or the nitrogen-containing five-membered heterocyclic skeleton has a high triplet excitation energy, but since its electron-accepting property is low, an iridium complex having such a skeleton as a ligand has a high HOMO level and LUMO level, and hole carriers are injected. has a high HOMO level and LUMO level, and hole carriers are injected. ​​​​​It is easy to insert and difficult for electron carriers to be injected. Therefore, an iridium complex having a more electron-accepting skeleton in the ligand is being developed. in the ligand.

[0011] On the other hand, an iridium complex having a highly electron-accepting skeleton in the ligand has a low HOMO level and LUMO level, is easy for electron carriers to be injected, and is difficult for hole carriers to be injected. Therefore, when excitation by direct recombination of carriers is difficult, or when it is difficult for a light-emitting element to emit light efficiently there may be cases.

[0012] Therefore, in one aspect of the present invention, in a light-emitting element having a phosphorescent material, it is an object to provide a light-emitting element with high luminous efficiency. Or, in one aspect of the present invention, it is an object to provide a light-emitting element with reduced power consumption. Or, in one aspect of the present invention, it is an object to provide a highly reliable light-emitting element. Or, in one aspect of the present invention, it is an object to provide a novel light-emitting element. Or, in one aspect of the present invention, it is an object to provide a novel light-emitting device. Or, in one aspect of the present invention, it is an object to provide a novel display device.

[0013] 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 than the above are obvious from the description in the specification etc., and it is possible to extract other problems than the above from the description in the specification etc.

Means for Solving the Problems

[0014] One aspect of the present invention is a light-emitting element having an excitation complex that can efficiently excite a phosphorescent material. ​

[0015] Therefore, one aspect of the present invention is a method for producing a photocatalytic reaction system comprising: a first organic compound; a second organic compound; and a guest material. a light-emitting device having a first organic compound and a second organic compound, The HOMO level of the first organic compound is lower than the LUMO level of the second organic compound. The LUMO level of the guest material is lower than the OMO level of the first organic compound. The energy difference between the LUMO level and the HOMO level of the guest material is lower than that of the first organic compound. the energy difference between the LUMO level of the first organic compound and the HOMO level of the second organic compound is greater than the The guest material has a function of converting triplet excitation energy into luminescence, and the first The light-emitting element is a combination of an organic compound and a second organic compound that form an exciplex. .

[0016] Another aspect of the present invention is a method for producing a semiconductor device comprising: and a LUMO level of the first organic compound is lower than that of the second organic compound. The HOMO level of the first organic compound is lower than the LUMO level of the second organic compound. The LUMO level of the guest material is lower than the LUMO level of the first organic compound. The energy difference between the LUMO level and the HOMO level of the guest material is low, and the energy difference between the LUMO level and the HOMO level of the first organic compound is low. The energy difference between the LUMO level of the first organic compound and the HOMO level of the second organic compound is larger than that The photoresist material has a function of converting triplet excitation energy into light emission, and the first photoresist material has a function of converting triplet excitation energy into light emission. The guest material is a combination of an organic compound and a second organic compound that forms an exciplex. The energy difference between the LUMO level of the first organic compound and the HOMO level of the second organic compound is It is a light-emitting element having a transition energy or higher calculated from an absorption edge in an absorption spectrum.

[0017] Another aspect of the present invention is a light-emitting element having a first organic compound, a second organic compound, and a guest material wherein the LUMO level of the first organic compound is lower than the LUMO level of the second organic compound, the HOMO level of the first organic compound is lower than the HO MO level of the second organic compound, the LUMO level of the guest material is lower than the LUMO level of the first organic compound , the energy difference between the LUMO level and the HOMO level of the guest material is larger than the energy difference between the LUMO level of the first organic compound and the HOMO level of the second organic compound, the guest material has a function capable of converting triplet excitation energy into light emission, and the first organic compound and the second organic compound form an excitation complex, and the energy difference between the LUMO level of the guest material and the HOMO level of the second organic compound is equal to or higher than the energy of the light emission exhibited by the guest material is a light-emitting element. Moreover, in each of the above configurations, the energy difference between the LUMO level and the HOMO level of the guest material is preferably 0.4 eV or more larger than the transition energy calculated from the absorption edge in the absorption spectrum of the guest material.

[0018] Furthermore, in each of the above configurations, the energy difference between the LUMO level and the HOMO level of the guest material is preferably 0.4 eV or more larger than the energy of the light emission exhibited by the guest material.

[0019] In addition, in each of the above configurations, it is preferable that the excitation complex has a function of donating excitation energy to the guest material. Also, the emission spectrum exhibited by the excitation complex is the absorption spectrum of the guest material

[0020] ​ It is preferable that the absorption band of the terbium-containing fluorine-containing compound has a region overlapping with the absorption band on the longest wavelength side of the spectrum.

[0021] In each of the above structures, the guest material preferably contains iridium.

[0022] In each of the above structures, the first organic compound has a function of transporting electrons. It is preferable that the second organic compound has a function of transporting holes. The first organic compound has a π-electron deficient heteroaromatic ring skeleton, and the second organic compound has a π-electron deficient heteroaromatic ring skeleton. It is preferable that the compound has at least one of a molecule-excess type heteroaromatic ring skeleton and an aromatic amine skeleton.

[0023] Another embodiment of the present invention is a light-emitting element having any of the above structures, and a color filter, a seal, or Another embodiment of the present invention is a display device including the display device. The electronic device according to the present invention includes a display device and a housing or a touch sensor. The present invention is an illumination device having a light-emitting element having any of the above configurations and a housing or a touch sensor. Further, one embodiment of the present invention is 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 in this specification includes image display devices, Also, the light emitting device may have a connector, such as an FPC (Fl exible Printed Circuit), TCP (Tape Carrier) The module has a printed wiring board at the end of the TCP. The module is mounted with a COG (Chip On Glass) method, and the light emitting element is A module in which C (integrated circuit) is directly mounted may also include a light emitting device. Effect of the Invention

[0024] According to one aspect of the present invention, in a light-emitting element having a phosphorescent material, a light-emitting element with high luminous efficiency can be provided. Or, according to one aspect of the present invention, a light-emitting element with reduced power consumption can be provided. Or, according to one aspect of the present invention, a light-emitting element with excellent reliability can be provided. Or, according to one aspect of the present invention, a novel light-emitting element can be provided. Or, according to one aspect of the present invention, a novel light-emitting device can be provided. Also or, according to one aspect of the present invention, a novel display device can be provided.

[0025] 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 the Drawings

[0026]

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Embodiments for Carrying Out the Invention

[0027] 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 is not interpreted as being limited to the content of the embodiments shown below.

[0028] Note that the positions, sizes, ranges, etc. of each component shown in the drawings and the like may not represent the actual positions, sizes, ranges, etc. for the sake of easy understanding. For this reason, the disclosed invention is not necessarily limited to the positions, sizes, ranges, etc. disclosed in the drawings and the like.

[0029] Also, in this specification and the like, ordinal numbers such as first, second, etc. are used for convenience, and may not indicate the process order or the stacking order. Therefore, for example, "first" can be appropriately replaced with "second" or "third", etc. for explanation. Also, the ordinal numbers described in this specification and the like may not match the ordinal numbers used to specify an aspect of the present invention.

[0030] Also, in this specification and the like, when explaining the configuration of the invention using the drawings, the same reference numerals may be commonly used among different drawings to refer to the same thing.

[0031] Also, in this specification and the like, the term "film" and the term "layer" may be used interchangeably with each other. It is possible to replace. 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".

[0032] In addition, in this specification and the like, the singlet excited state (S * ) refers to 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. Also, the triplet excited state (T ) refers to 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. In addition, in this specification and the like, even when simply referred to as a singlet excited state or a singlet excitation energy level, it may represent the lowest singlet excited state or the S1 level. Also, even when referred to as a triplet excited state or a triplet excitation energy level, it may represent the lowest triplet excited state or the T1 level.

[0033] In addition, in this specification and the like, a fluorescent material is a material that emits light in the visible light region when relaxing from a singlet excited state to the ground state. On the other hand, a phosphorescent material is a material that emits light in the visible light region at room temperature when relaxing from a triplet excited state to the ground state. In other words, a phosphorescent material is one of the materials that can convert triplet excitation energy into visible light.

[0034] Also, the phosphorescent emission energy or the triplet excitation energy is the shortest wavelength side of the phosphorescent emission. ​​​​​​​It can be derived from the wavelength of the emission peak (including the shoulder). The phosphorescent emission is observed by performing a time-resolved photoluminescence method in a low-temperature (e.g., 10 K) environment. Also, the emission energy of the thermally activated delayed fluorescence can be derived from the wavelength of the emission peak (including the shoulder) on the shortest wavelength side of the thermally activated delayed fluorescence. Note that in this specification and the like, room temperature refers to any temperature from 0°C to 40°C.

[0035] Note that in this specification and the like, room temperature refers to any temperature from 0°C to 40°C.

[0036] In addition, in this specification and the like, the blue wavelength region is a wavelength region from 400 nm to less than 500 nm, and blue emission is emission having at least one emission spectrum peak in this region. Note that in this specification and the like, room temperature refers to any temperature from 0°C to 40°C. Also, the green wavelength region is a wavelength region from 500 nm to less than 580 nm, and green emission is emission having at least one emission spectrum peak in this region. Note that in this specification and the like, room temperature refers to any temperature from 0°C to 40°C. Also, the red wavelength region is a wavelength region from 580 nm to 680 nm, and red emission is emission having at least one emission spectrum peak in this region. Note that in this specification and the like, room temperature refers to any temperature from 0°C to 40°C.

[0037] (Embodiment 1) In this embodiment, an emission element according to one aspect of the present invention will be described below with reference to FIGS. 1 and 2. Note that in this specification and the like, room temperature refers to any temperature from 0°C to 40°C.

[0038] <Configuration example of the emission element> First, the configuration of the emission element according to one aspect of the present invention will be described below with reference to FIGS. 1(A) and (B). Note that in this specification and the like, room temperature refers to any temperature from 0°C to 40°C.

[0039] FIG. 1(A) is a cross-sectional schematic view of an emission element 152 according to one aspect of the present invention.

[0040] The emission element 152 has a pair of electrodes (electrode 101 and electrode 102), and between the pair of electrodes It has an EL layer 100 provided therein. The EL layer 100 has at least a light-emitting layer 140. .

[0041] Also, 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 140.

[0042] In this embodiment, among a pair of electrodes, electrode 101 is used as the anode and electrode 1 02 is used as the cathode for explanation. However, the configuration of the light-emitting element 152 is not limited to this. That is, electrode 101 may be used as the cathode, electrode 102 may be used as the anode, and the lamination of each layer between the electrodes may be in the reverse order. That is, from the anode side, the hole injection layer 111, the hole transport layer 112, the light-emitting layer 140, the electron transport layer 118, and the electron injection layer 119 may be laminated in this order. .

[0043] Note that the configuration of the EL layer 100 is not limited to the configuration shown in Fig. 1(A), and it may have 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 the injection barrier of holes or electrons, improving the transportability of holes or electrons, inhibiting the transportability of holes or electrons, or suppressing the quenching phenomenon by the electrodes. Note that each functional layer may be a single layer or a structure in which a plurality of layers are laminated.

[0044] Fig. 1(B) is a cross-sectional schematic view showing an example of the light-emitting layer 140 shown in Fig. 1(A). The light-emitting layer 140 shown in Fig. 1( B) has a host material 141 and a guest material 142. Also The host material 141 has an organic compound 141_1 and an organic compound 141_2.

[0045] In addition, as the guest material 142, a light-emitting organic material may be used, and the light-emitting organic material is preferably a material that can emit phosphorescence (hereinafter also referred to as a phosphorescent material). In the following description, a configuration using a phosphorescent material as the guest material 142 will be described. Note that the guest material 142 may be read as a phosphorescent material.

[0046] <Light Emission Mechanism of Light-Emitting Element> Next, the light emission mechanism of the light-emitting layer 140 will be described below.

[0047] The organic compound 141_1 and the organic compound 141_2 included in the host material 141 in the light-emitting layer 140 form an exciplex (also referred to as an exciplex, an exiplex, or an Exciplex).

[0048] The combination of the organic compound 141_1 and the organic compound 141_2 may be any combination that can form 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 easier to form a donor-acceptor type exciplex, and the exciplex can be formed efficiently.

[0049] In addition, as the combination of the organic compound 141_1 and the organic compound 141_2, one has a HOMO level lower than the highest occupied molecular orbital (also referred to as the HOMO) level of the other, and moreover, the lowest unoccupied orbital of the other It preferably has a LUMO level lower than the lowest unoccupied molecular orbital (also referred to as the LUMO level). For example, as shown in the energy band diagram of Fig. 2(A), when the organic compound 141_1 has electron

[0050] transportability and the organic compound 141_2 has hole transportability, the HOMO level of the organic compound 141_1 is lower than the HOMO level of the organic compound 141_2, and the LUMO level of the organic compound 1 41_1 is preferably lower than the LUMO level of the organic compound 141_2.

[0051] In this case, the exciplex formed by the organic compound 141_1 and the organic compound 141_2 has an excitation energy substantially corresponding to the energy difference (ΔE ) between the LUMO level of the organic compound 141_1 and the HOMO level of the organic compound 141_2. Ex

[0052] Also, the difference between the HOMO level of the organic compound 141_1 and the HOMO level of the organic compound 141_2, and the difference between the LUMO level of the organic compound 141_1 and the LUMO level of the organic compound 141_2 are each preferably 0.1 eV or more, more preferably 0.2 eV or more. By having this energy difference, it is suitable because the electron carriers and hole carriers injected from a pair of electrodes (electrode 101 and electrode 102) are more easily injected into the organic compound 141_1 and the organic compound 141_2, respectively.

[0053] In Fig. 2(A), Host(141_1) represents the organic compound 141_1, Host(141_2) represents the organic compound 141_2, and Guest(142) represents the guest. ​​​Represents material 142, ΔE Ex represents the energy difference between the LUMO level of organic compound 141_1 and the HOMO level of organic compound 141 _2, and ΔE B represents the energy difference between the LUMO level of guest material 142 and the HOMO level of organic compound 141_2, and ΔE G represents the energy difference between the LUMO level and the HOMO level of guest material 1 42, which are notations and symbols.

[0054] For the emission of the guest material 142 to have a short emission wavelength and high emission energy, the energy difference (ΔE G ) between the LUMO level and the HOMO level of the guest material 142 is preferably large. On the other hand, in the light-emitting element 152, in order to reduce the driving voltage, it is preferable to excite with as small an excitation energy as possible. For this purpose, the excitation energy of the exciplex formed by organic compound 141_1 and organic compound 141_2 should be smaller. Therefore, the energy difference (ΔE ) between the LUMO level of organic compound 141_1 and the HOMO level of organic compound 14 1_2 is preferably small. Ex

[0055] Since the guest material 142 is a phosphorescent light-emitting material, it has a function of converting triplet excitation energy into light emission. Also, the triplet excited state is more stable in energy than the singlet excited state. Therefore, the guest material 142 can exhibit light emission with an energy smaller than the energy difference (ΔE ) between the LUMO level and the HOMO level. Here, the energy difference (ΔE G ) between the LUMO level and the HOMO level of the guest material 142 is such that the energy difference (ΔE G ) between the LUMO level and the HOMO level of the guest material 142 is smaller than that of the organic compound Energy difference between the LUMO level of compound 141_1 and the HOMO level of organic compound 141_2 (ΔE Ex ) Even when it is larger, the energy of the emission exhibited by the guest material 142 ( Abbreviation: ΔE Em ) or the transition energy calculated from the absorption edge in the absorption spectrum (Abbreviation: ΔE abs ) is equal to or smaller than ΔE Ex , then from the exciplex formed by organic compound 14 1_1 and organic compound 141_2, the inventors have found that the transfer of excitation energy to the guest material 142 becomes possible and luminescence can be obtained from the guest material 142. When ΔE of the guest material 142 is larger than the energy of the emission exhibited by the guest material 142 (ΔE G ) or the transition energy (ΔE ) calculated from the absorption edge in the absorption spectrum, in order to directly electrically excite the guest material 142, a large amount of electrical energy corresponding to ΔE Em is required, so the driving voltage of the light-emitting device increases. - (ΔE abs ) G However, in one aspect of the present invention, an exciplex is electrically excited by electrical energy corresponding to ΔE (smaller than ΔE Ex (ΔE G ), and the excitation state of the guest material 142 is generated by energy transfer from the exciplex. Therefore, luminescence from the guest material 142 can be obtained with a low driving voltage and high efficiency. That is, when ΔE is considerably larger than the energy of the emission exhibited by the guest material 142 (ΔE ) or the transition energy (ΔE G ) calculated from the absorption spectrum (for example, when the guest material is a blue light-emitting material), in the case of the present invention (ΔE Em ) or the transition energy calculated from the absorption spectrum (ΔE abs ) ​​​​One aspect of the above is particularly beneficial.

[0056] When the guest material 142 has a heavy metal, spin-orbit interaction (the spin angular momentum of electrons) and the orbital angular momentum) promotes intersystem crossing between the singlet and triplet states. Therefore, the transition between the singlet ground state and the triplet excited state is forbidden in the guest material 142. In other words, the singlet ground state and triplet excited state of the guest material 142 may not be the same. The efficiency of the emission and the probability of absorption associated with the transition between The spin material 142 preferably contains a metal element having a large spin-orbit coupling, and in particular, platinum. Group elements (ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (O It is preferable that the metal oxide has iridium (Ir) or platinum (Pt), among which iridium (Ir) or platinum (Pt) is preferable. The presence of 100% Cr in the ZnO-containing ZnO-based ... This can increase the probability, which is preferable.

[0057] In order for the guest material 142 to be stable and highly reliable, the L It is preferable that the UMO level is low. To achieve this, the heavy metal atom of the guest material 142 is It is also preferable that the ligand to be coordinated to the nucleophile has a high electron-accepting property and a low LUMO level.

[0058] The guest material with the above structure is a molecule with a low LUMO level that easily accepts electrons. When the guest material 142 has a molecular structure that easily accepts electrons, The LUMO level of the material 142 may be lower than the LUMO level of the organic compound 141_1. Furthermore, ΔE G is ΔE Ex If the HOMO level of the guest material 142 is greater than It becomes lower than the HOMO level of the organic compound 141_2. In this case, the guest material 142 The energy difference between the HOMO level of the guest material 142 and the HOMO level of the organic compound 141_2 is the same as the energy difference between the LUMO level of the guest material 142 and the LUMO level of the organic compound 141_1, and becomes larger.

[0059] Here, when the LUMO level of the guest material 142 is lower than the LUMO level of the organic compound 141_1, and the HOMO level of the guest material 142 is lower than the HOMO level of the organic compound 141_2, among the carriers (holes and electrons) injected from the pair of electrodes (electrode 101 and electrode 102), the electrons injected from the cathode are easily injected into the guest material 142 in the light-emitting layer 140, and the holes injected from the anode are easily injected into the organic compound 141_2. As a result, among the materials included in the light-emitting layer 140, when the material having the lowest LUMO level is the guest material 142 and the material having the highest HOMO level is the organic compound 141_2, an exciplex may be formed between the organic compound 141_2 and the guest material 142. In particular, as the energy difference (abbreviation: ΔE between the HOMO level of the organic compound 141_2 and the LUMO level of the guest material 142 becomes smaller than the energy of the emission of the guest material (ΔE ), the formation of the exciplex formed between the organic compound 141_2 and the guest material 142 becomes dominant. In this case, since it becomes difficult to generate an excited state in the guest material 142 alone, the luminous efficiency of the light-emitting element decreases. B ), the energy of the emission of the guest material (ΔE Em ). As it becomes smaller than the energy of the emission of the guest material (ΔE ), the formation of the exciplex formed between the organic compound 141_2 and the guest material 142 becomes dominant. In this case, since it becomes difficult to generate an excited state in the guest material 142 alone, the luminous efficiency of the light-emitting element decreases.

[0060] The above reaction can be represented by the following formula (G1) or (G2).

[0061] D​​​​​​​​+ +G - → (D G) * (G1) D+G * → (D G) * (G2)

[0062] Formula (G1) shows that organic compound 141_2 accepts a hole (D + ), and guest material 142 Accepts electrons (G - ) The organic compound 141_2 and the guest material 142 form an exciplex. Body((D・G) * ) is produced. In addition, formula (G2) shows the reaction in which the guest Material 142(G * ) interacts with the ground state organic compound 141_2(D) The organic compound 141_2 and the guest material 142 are exciplexes ((D·G) * ) The organic compound 141_2 and the guest material 142 form an exciplex ((D·G) * ) By forming * ) is difficult to generate. Wow.

[0063] The exciplex formed by the organic compound 141_2 and the guest material 142 is The energy difference (ΔE B ) The resulting excited complex has roughly the same excitation energy. However, the organic compound 141 The energy difference (ΔE B )but , the luminescence energy (ΔE Em ) or in the absorption spectrum The transition energy (ΔE abs ) or more, organic compound 1 The reaction of forming an exciplex between the guest material 41_2 and the guest material 142 can be suppressed. The present inventors have found that efficient light emission can be obtained from the material 142. In this case, ΔE B ΔE abs Since the valence energy of the guest material 142 is small, It is easier to form an exciplex between the organic compound 141_2 and the guest material 142. The material 142 receives the excitation energy and becomes excited, which has lower energy and is more stable. do.

[0064] As described above, the energy difference (Δ E G ) is the LUMO level of organic compound 141_1 and the HOMO level of organic compound 141_2. The energy difference (ΔE Ex ), the absorption spectrum of the guest material142 is The transition energy (ΔE abs ) is ΔE Ex is equivalent to If it is smaller than 141_1, the excitation light formed by organic compound 141_2 is The excitation energy can be efficiently transferred from the complex to the guest material 142. As a result, a light-emitting element with low voltage and high efficiency can be obtained, which is one of the features of one embodiment of the present invention. In this case, ΔE abs ≦ΔE Ex <ΔE G (ΔE abs is ΔE Ex is less than or equal to Δ E Ex is ΔE G Therefore, ΔE abs is ΔE G Less than In this case, the mechanism of one aspect of the present invention is preferable. In other words, ΔE G is ΔEabs When it is larger, the mechanism of one aspect of the present invention is suitable. More specifically, the energy difference (ΔE ) between the LUMO level and the HOMO level of the guest material 142 is preferably larger than 0.4 eV than the transition energy (ΔE ) calculated from the absorption edge in the absorption spectrum of the guest material 14 G 2. Also, since the energy of the light emission exhibited by the guest material 142 ([ΔE ) is equal to or smaller than ΔE abs , the energy difference (ΔE ) between the LUMO level and the HOMO level of the guest material 142 is preferably larger than 0.4 eV than the energy of the light emission ([ΔE ) exhibited by the guest material 142. Note that the energy of the light emission ([ΔE Em ) can be derived from the wavelength of the light emission peak (maximum value or including shoulder) on the shortest wavelength side of the emission spectrum. abs Moreover, when the LUMO level of the guest material 142 is lower than the LUMO level of the organic compound 141_1, as described above, ΔE ≦ΔE G (ΔE is ΔE Em or less), or ΔE Em ≦ΔE (ΔE

[0065] is preferably satisfied. Therefore, ΔE ≦ΔE abs <ΔE B (ΔE abs is ΔE B or less), or ΔE Em ≦ΔE B (ΔE Em is ΔE B or less) is preferably satisfied. Thus, ΔE abs ≦ΔE B <ΔE Ex <ΔE G (ΔE abs is ΔE B or less, and ΔE B is smaller than ΔE Ex , and ΔE is smaller than ΔE Ex is ΔEG smaller), or ΔE Em ≤ ΔE B < ΔE Ex < ΔE G ( ΔE Em is ΔE B or less, and ΔE B is ΔE Ex smaller than, and ΔE Ex is ΔE G smaller is preferable. These conditions are also an important discovery in one aspect of the present invention.

[0066] Note that as the emission wavelength of the guest material 142 becomes shorter and the emission energy (ΔE Em ) increases, the energy difference (Δ E E G ) between the LUMO level and the HOMO level of the guest material 142 increases. Accordingly, a larger energy is required to electrically excite the guest material 142. However, in one aspect of the present invention, the transition energy (ΔE ) calculated from the absorption edge in the absorption spectrum of the guest material 142 is equal to or smaller than ΔE abs . If so, the guest material 142 can be excited with an energy of about ΔE Ex which is smaller than ΔE G . Therefore, the power consumption of the light-emitting device can be reduced. Accordingly, the energy difference between the transition energy (ΔE Ex level) calculated from the absorption edge in the absorption spectrum of the guest material 142 and the energy difference (ΔE ) between the LUMO level and the HOMO level of the guest material 142 is preferably larger (that is, particularly in the case of a guest material exhibiting blue light emission), the effect of the light-emitting mechanism of one aspect of the present invention becomes remarkable. The transition energy (ΔE abs ) calculated from the absorption edge in the absorption spectrum of the guest material 142, and the energy difference (ΔE ) between the LUMO level and the HOMO level of the guest material 142 G is larger, the effect of the light-emitting mechanism of one aspect of the present invention becomes more remarkable (that is, particularly in the case of a guest material exhibiting blue light emission).

[0067] However, when the transition energy (ΔE ) calculated from the absorption edge in the absorption spectrum of the guest material 142 becomes small, the energy of the light emission exhibited by the guest material 142 also becomes small abs . Therefore, it becomes difficult to obtain light emission having a high energy such as blue light emission. That is, when the difference between ΔE and ΔE abs becomes too large, it becomes difficult to obtain light emission having a high energy such as blue light emission. G From these facts, the energy difference (ΔE

[0068] ) between the LUMO level and the HOMO level of the guest material 142 is preferably larger than the transition energy (ΔE ) calculated from the absorption edge in the absorption spectrum of the guest material 142, in the range of 0.4 eV or more and 0.8 eV or less, G more preferably in the range of 0.5 eV or more and 0.8 eV or less. Further, the energy (ΔE ) of the light emission exhibited by the guest material 142 is equal to or smaller than ΔE abs . Therefore, the energy difference (ΔE ) between the LUMO level and the HOMO level of the guest material 142 is preferably larger than the energy (ΔE ) of the light emission exhibited by the guest material 142, in the range of 0.4 eV or more and 0.8 eV or less, Em more preferably in the range of 0.5 eV or more and 0.8 eV or less. abs Further, the difference between the LUMO level of the guest material 142 and the LUMO level of the organic compound 141_1 is preferably 0.05 eV or more and 0.4 eV or less. An appropriate electron trap brings about the effect of extending the lifetime of the light emitting device, but if the LUMO level of the guest material is too low, as described above, ΔE G Further, the difference between the LUMO level of the guest material 142 and the LUMO level of the organic compound 141_1 is preferably 0.05 eV or more and 0.4 eV or less. An appropriate electron trap brings about the effect of extending the lifetime of the light emitting device, but if the LUMO level of the guest material is too low, as described above, ΔE Em is preferably larger than the energy (ΔE ) of the light emission exhibited by the guest material 142, in the range of 0.4 eV or more and 0.8 eV or less, more preferably in the range of 0.5 eV or more and 0.8 eV or less.

[0069] Also, the difference between the LUMO level of the guest material 142 and the LUMO level of the organic compound 141_1 is preferably 0.05 eV or more and 0.4 eV or less. An appropriate electron trap brings about the effect of extending the lifetime of the light emitting device, but if the LUMO level of the guest material is too low, as described above, ΔE the above-mentioned ΔE ​​​​​​B This is because it becomes smaller. Further, the difference between the HOMO level of the guest material 142 and the HOMO level of the organic compound 141_2 is preferably 0.05 eV or more, more preferably 0.1 eV or more, and even more preferably 0.2 eV or more. By setting such an energy level correlation, it is suitable because the injection of hole carriers into the organic compound 141_2 is reduced.

[0070] Further, the energy difference (ΔE ) between the LUMO level of the organic compound 141_1 and the HOMO level of the organic compound 141_2 is smaller than the energy difference between the LUMO level and the HOMO level of the organic compound 141_1, and the energy difference between the LUMO level and the HOMO level of the organic compound 141_2, respectively. Therefore, it is more energetically stable to form an exciplex than for the organic compound 141_1 and the organic compound 141_2 to form an excited state alone. Also Ex Further, when the energy difference (ΔE G ) between the LUMO level and the HOMO level of the guest material 142 is larger than the energy difference (ΔE ) between the LUMO level of the organic compound 141_1 and the HOMO level of the organic compound 141_2, as the excited state formed by the recombination of the carriers (holes and electrons) injected into the light-emitting layer 140, the exciplex formed by the organic compound 141_1 and the organic compound 141_2 is more energetically stable. Therefore, most of the excited states generated in the light-emitting layer 140 will exist as exciplexes formed by the organic compound 141_1 and the organic compound 141_2. Therefore, according to the configuration of one aspect of the present invention, by facilitating the transfer of excitation energy from the exciplex to the guest material 142, light emission Ex The driving voltage of the optical element can be reduced, and the luminous efficiency can be increased.

[0071] Note that the HOMO level of the guest material 142 may be higher or lower than the HOMO level of the organic compound 141_1. It may be high or low.

[0072] Also, since the LUMO level of the guest material 142 is lower than the LUMO level of the organic compound 141_1, the guest material 142 functions as an electron trap in the light-emitting layer 140. When the guest material 142 functions as an electron trap, the carrier balance in the light-emitting layer can be easily controlled, and the effect of extending the lifetime can be obtained, which is preferable. When the guest material 142 functions as an electron trap, the carrier balance in the light-emitting layer can be easily controlled, and the effect of extending the lifetime can be obtained, which is preferable. When the guest material 142 functions as an electron trap, the carrier balance in the light-emitting layer can be easily controlled, and the effect of extending the lifetime can be obtained, which is preferable.

[0073] In addition, when the combination of the organic compound 141_1 and the organic compound 141_2 is a combination of a compound having hole-transporting properties and a compound having electron-transporting properties, the carrier balance can be easily controlled by the mixing ratio. Specifically, the range of the compound having hole-transporting properties: the compound having electron-transporting properties = 1:9 to 9:1 (weight ratio) is preferable. In addition, when the combination of the organic compound 141_1 and the organic compound 141_2 is a combination of a compound having hole-transporting properties and a compound having electron-transporting properties, the carrier balance can be easily controlled by the mixing ratio. Specifically, the range of the compound having hole-transporting properties: the compound having electron-transporting properties = 1:9 to 9:1 (weight ratio) is preferable. In addition, when the combination of the organic compound 141_1 and the organic compound 141_2 is a combination of a compound having hole-transporting properties and a compound having electron-transporting properties, the carrier balance can be easily controlled by the mixing ratio. Specifically, the range of the compound having hole-transporting properties: the compound having electron-transporting properties = 1:9 to 9:1 (weight ratio) is preferable. In addition, when the combination of the organic compound 141_1 and the organic compound 141_2 is a combination of a compound having hole-transporting properties and a compound having electron-transporting properties, the carrier balance can be easily controlled by the mixing ratio. Specifically, the range of the compound having hole-transporting properties: the compound having electron-transporting properties = 1:9 to 9:1 (weight ratio) is preferable. In addition, since the carrier balance can be easily controlled by having this configuration, the control of the carrier recombination region can also be easily performed. In addition, since the carrier balance can be easily controlled by having this configuration, the control of the carrier recombination region can also be easily performed.

[0074] The exciplex formed by the organic compound 141_1 and the organic compound 141_2 has a HOMO molecular orbital in one organic compound and a LUMO molecular orbital in the other organic compound. Therefore, the overlap between the HOMO molecular orbital and the LUMO molecular orbital is extremely small. That is, the difference between the singlet excitation energy level and the triplet excitation energy level of the exciplex becomes small. The exciplex formed by the organic compound 141_1 and the organic compound 141_2 has a HOMO molecular orbital in one organic compound and a LUMO molecular orbital in the other organic compound. Therefore, the overlap between the HOMO molecular orbital and the LUMO molecular orbital is extremely small. That is, the difference between the singlet excitation energy level and the triplet excitation energy level of the exciplex becomes small. The exciplex formed by the organic compound 141_1 and the organic compound 141_2 has a HOMO molecular orbital in one organic compound and a LUMO molecular orbital in the other organic compound. Therefore, the overlap between the HOMO molecular orbital and the LUMO molecular orbital is extremely small. That is, the difference between the singlet excitation energy level and the triplet excitation energy level of the exciplex becomes small. The exciplex formed by the organic compound 141_1 and the organic compound 141_2 has a HOMO molecular orbital in one organic compound and a LUMO molecular orbital in the other organic compound. Therefore, the overlap between the HOMO molecular orbital and the LUMO molecular orbital is extremely small. That is, the difference between the singlet excitation energy level and the triplet excitation energy level of the exciplex becomes small. Therefore, the exciplex formed by the organic compound 141_1 and the organic compound 141_2 is a single The difference between the singlet excitation energy level and the triplet excitation energy level is preferably greater than 0 eV and less than or equal to 0.2 eV, more preferably greater than 0 eV and less than or equal to 0.1 eV.

[0075] Here, the correlation of the energy levels among the organic compound 141_1, the organic compound 141_2, and the guest material 142 in the light-emitting layer 140 is shown in FIG. 2(B). Note that the notations and symbols in FIG. 2(B) are as follows. ·Host(141_1): Host material (organic compound 141_1) ·Host(141_2): Host material (organic compound 141_2) ·Guest(142): Guest material 142 (phosphorescent material) ·Exciplex: Excitation complex (organic compound 141_1 and organic compound 141_2) ·S PH1 : S1 level of the host material (organic compound 141_1) ·T PH1 : T1 level of the host material (organic compound 141_1) ·S PH2 : S1 level of the host material (organic compound 141_2) ·T PH2 : T1 level of the host material (organic compound 141_2) ·S PG : S1 level of the guest material 142 (phosphorescent material) ·T PG : T1 level of the guest material 142 (phosphorescent material) ·S PE : S1 level of the excitation complex ·T PE : T1 level of the excitation complex

[0076] In the light-emitting element according to one aspect of the present invention, the organic compound 141_1 and the organic compound 141_2 included in the light-emitting layer 140 form an excitation complex. The lowest level of the singlet excited state of the excitation complex (S PE ) and the lowest level of the triplet excited state of the excitation complex (TPE ) are adjacent to each other (See route E7 in Figure 2(B)).

[0077] An exciplex is an excited state consisting of two substances. In the case of photoexcitation, They are formed by the interaction of one substance with another substance in its ground state, and When the two substances that formed the exciplex reach the ground state by emitting light, In the case of electrical excitation, when one of them becomes excited, it quickly Alternatively, one atom can transfer a hole and the other an electron. They can receive electrons and interact with each other to rapidly form exciplexes. In the case of Therefore, most of the excited states in the light-emitting layer 140 exist as exciplexes. It is possible to obtain the excited energy level of the exciplex (S E or T E ) forms an exciplex The S1 level (S PH1 and S PH2 ) is lower than that of the host material 141 at lower excitation energies. This allows the driving voltage of the light emitting element 152 to be reduced. It can be reduced.

[0078] And the (S PE ) and (T PE ) and the energy of the guest material 142 The lowest triplet excited state level (T PG ) to obtain light emission ( See Figure 2(B) Routes E8 and E9).

[0079] Note that the T1 level (T PE ) of the exciplex is preferably higher than the T1 level (T PG ) of the guest material 142. By setting the relationship of the T1 levels in this way, the singlet excitation energy and triplet excitation energy of the generated exciplex can be transferred from the S1 level (S ) and the PE T1 level (T ) of the exciplex to the T1 level (T PE ) of the guest material 142. PG ) This is possible.

[0080] By configuring the light-emitting layer 140 as described above, it becomes possible to efficiently obtain light emission from the guest material 142 (phosphorescent material ) of the light-emitting layer 140.

[0081] Note that the processes of Route E7, Route E8, and Route E9 shown above may be referred to as ExTET (Exciplex-Triplet Energy Transfer ) in this specification and the like. In other words, in the light-emitting layer 140, there is donation of excitation energy from the exciplex to the guest material 142 . Also, in this case, it is not necessarily required that the reverse intersystem crossing efficiency from T PE to S PE is high, nor is it necessary that the light emission quantum yield from S is high. Therefore, it becomes possible to widely select materials. PE

[0082] Note that the above reactions can be represented by the following formulas (G3) to (G5).

[0083] D + +A - → (D·A) * (G3) (D·A) * +G → D+A+G * (G4) G *→ G + hν (G5)

[0084] Formula (G3) is a reaction in which one of the organic compound 141_1 and the organic compound 141_2 accepts a hole (D ), and the other accepts an electron (A + ), thereby generating an exciplex ((D·A) - ) between the organic compound 141_1 and the organic compound 141_2. Further, formula (G4) * is a reaction in which energy transfer occurs from the exciplex ((D·A) ) to the guest material 142 (G), generating an excited state (G * ) of the guest material 142. Thereafter, as in formula (G5) , light emission (hν) occurs from the excited state of the guest material 142 * . Note that, in order to efficiently transfer the excitation energy from the exciplex to the guest material 142

[0085] , it is preferable that the T1 level (T ) of the exciplex is lower than the T1 levels of each of the organic compounds (organic compound 141_1 and organic compound 141_2) constituting the host material forming the exciplex PE . This makes it difficult for quenching of the triplet excitation energy of the exciplex by each organic compound to occur, and energy transfer to the guest material 142 occurs efficiently . Further, when the organic compound 141_2 has a strongly donor-like skeleton, holes injected into the light-emitting layer 140 are easily injected into and transported by the organic compound 141_2. Also, when the organic compound

[0086] 141_1 has a strongly acceptor-like skeleton, electrons injected into the light-emitting layer 140 are easily injected into and transported by the organic compound 141_1. When electrons are injected into the organic compound 141_1 and holes are injected into the organic compound 141_2, respectively, the organic compound 141_1 and the organic compound 141_2 are caused to form an exciplex by the injection of electrons into the organic compound 141_1 and holes into the organic compound 141_2, respectively It easily forms an exciplex with the organic compound 141_2.

[0087] By configuring the light-emitting layer 140 as described above, light emission from the guest material 142 of the light-emitting layer 140 can be efficiently obtained.

[0088] <Energy transfer mechanism> Next, the governing factors of the intermolecular energy transfer process between the host material 141 and the guest material 142 will be described. As the mechanism of intermolecular energy transfer, two mechanisms, the Förster mechanism (dipole-dipole interaction) and the Dexter mechanism (electron exchange interaction), have been proposed. Here, the intermolecular energy transfer process between the host material 141 and the guest material 142 will be described, but the same applies when the host material 141 is an exciplex.

[0089] <<Förster mechanism>> In the Förster mechanism, energy transfer does not require direct contact between molecules. Energy transfer occurs through the resonance phenomenon of dipole vibrations between the host material 141 and the guest material 142. Due to the resonance phenomenon of dipole vibrations, the host material 141 transfers energy to the guest material 142, the excited host material 141 returns to the ground state, and the ground-state guest material 142 becomes excited. The rate constant k of the Förster mechanism is shown in Equation (1).

[0090] h*→g

[0091]

Equation

[0091] In Equation (1), ν represents the frequency, and f’ h (ν) represents the normalization of the host material 141. The normalized emission spectrum (fluorescence spectrum when discussing energy transfer from the singlet excited state, phosphorescence spectrum when discussing energy transfer from the triplet excited state) is represented, where ε ε g (ν) represents the molar extinction coefficient of the guest material 142, N represents Avogadro's number, n represents the refractive index of the medium, R represents the intermolecular distance between the host material 141 and the guest material 142 and 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 is 2 a coefficient (0 to 4) representing the orientation of the transition dipole moments of the host material 141 and the guest material 142. In the case of random orientation, K is = 2 / 3. 2

[0092] ≪Dexter mechanism≫ In the Dexter mechanism, the host material 141 and the guest material 142 approach the contact effective distance where orbital overlap occurs, and energy transfer occurs through the exchange of electrons between the electrons of the excited state host material 141 and the ground state guest material 14 2. The rate constant k of the Dexter mechanism is shown in Equation (2). h*→g

[0093]

Equation

[0094] In Equation (2), h is Planck's constant, K is a constant with the dimension of energy and ν represents the frequency, f’ h (ν) is the normalized emission spectrum of the host material 141 Spectrum (fluorescence spectrum when discussing energy transfer from the singlet excited state, phosphorescence spectrum when discussing energy transfer from the triplet excited state), and ε’ g (ν) represents the normalized absorption spectrum of the guest material 142, L represents the effective molecular radius, and R represents the intermolecular distance between the host material 141 and the guest material 142.

[0095] Here, the energy transfer efficiency φ from the host material 141 to the guest material 142 ET is expressed by the formula (3). k r is the emission process of the host material 141 (fluorescence when discussing energy transfer from the singlet excited state, phosphorescence when discussing energy transfer from the triplet excited state) rate constant, and k n is the non-emission process (thermal deactivation or intersystem crossing) rate constant of the host material 141, and τ represents the measured lifetime of the excited state of the host material 141.

[0096]

Formula

[0097] From formula (3), to increase the energy transfer efficiency φ ET , it can be seen that the rate constant k of energy transfer should be increased, and the other competing rate constant k h*→g + k r + k n (= 1 / τ) should be relatively small.

[0098] ≪Concept for enhancing energy transfer≫ In energy transfer by the Förster mechanism, the energy transfer efficiency φ ET is the quantity quantum yield φ (fluorescence quantum yield when discussing energy transfer from the singlet excited state, triplet When discussing energy transfer from the singlet excited state, it is preferable that the phosphorescence quantum yield) is high. Also, in the case of discussing energy transfer from the singlet excited state, the emission spectrum of the host material 141 (fluorescence spectrum when discussing energy transfer from the singlet excited state) and the absorption spectrum of the guest material 142 (absorption corresponding to the transition from the singlet ground state to the triplet excited state) preferably have a large overlap. Furthermore, it is preferable that the molar extinction coefficient of the guest material 142 is also high. This means that the emission spectrum of the host material 141 overlaps with the absorption band that appears on the longest wavelength side of the guest material 142.

[0099] Also, in energy transfer by the Dexter mechanism, to increase the rate constant k h*→g it is better that the emission spectrum of the host material 141 (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 guest material 142 (absorption corresponding to the transition from the singlet ground state to the triplet excited state) have a large overlap. Therefore, optimization of the energy transfer efficiency is achieved by the emission spectrum of the host material 141 overlapping with the absorption band that appears on the longest wavelength side of the guest material 142.

[0100] Note that, similar to the energy transfer from the host material 141 to the guest material 142, in the energy transfer process from the exciplex to the guest material 142, energy transfer occurs by both the Förster mechanism and the Dexter mechanism.

[0101] Therefore, one aspect of the present invention is an energy that can efficiently transfer energy to the guest material 142 An organic compound 141 that forms an exciplex having a function as a Lewis acid Provided is a light-emitting device having, as a host material, organic compound 141_1 and organic compound 141_2. The exciplex formed by organic compound 141_1 and organic compound 141_2 can be formed with an excitation energy lower than the excitation states of organic compound 141_1 and organic compound 141_2 alone. Therefore, the driving voltage can be reduced in the light-emitting device 152. Furthermore, in order to facilitate the energy transfer from the singlet excitation energy level of the exciplex to the triplet excitation energy level of the guest material 142, it is preferable that the emission spectrum of the exciplex and the absorption band that appears on the longest wavelength side (low energy side) of the absorption spectrum of the guest material 142 overlap. By establishing such a relationship between the emission spectrum and the absorption spectrum, the generation efficiency of the triplet excited state of the guest material 142 can be increased. Note that the exciplex generated in the light-emitting layer 140 has the characteristic that the singlet excitation energy level and the triplet excitation energy level are close to each other. Therefore, by overlapping the emission spectrum of the exciplex and the absorption band that appears on the longest wavelength side (low energy side) of the guest material 142, it is also possible to facilitate the energy transfer from the triplet excitation energy level of the exciplex to the triplet excitation energy level of the guest material 142. Therefore, the driving voltage can be reduced in the light-emitting device 152. Furthermore, in order to facilitate the energy transfer from the singlet excitation energy level of the exciplex to the triplet excitation energy level of the guest material 142, it is preferable that the emission spectrum of the exciplex and the absorption band that appears on the longest wavelength side (low energy side) of the absorption spectrum of the guest material 142 overlap. By establishing such a relationship between the emission spectrum and the absorption spectrum, the generation efficiency of the triplet excited state of the guest material 142 can be increased. Note that the exciplex generated in the light-emitting layer 140 has the characteristic that the singlet excitation energy level and the triplet excitation energy level are close to each other. Therefore, by overlapping the emission spectrum of the exciplex and the absorption band that appears on the longest wavelength side (low energy side) of the guest material 142, it is also possible to facilitate the energy transfer from the triplet excitation energy level of the exciplex to the triplet excitation energy level of the guest material 142. Furthermore, in order to facilitate the energy transfer from the singlet excitation energy level of the exciplex to the triplet excitation energy level of the guest material 142, it is preferable that the emission spectrum of the exciplex and the absorption band that appears on the longest wavelength side (low energy side) of the absorption spectrum of the guest material 142 overlap. By establishing such a relationship between the emission spectrum and the absorption spectrum, the generation efficiency of the triplet excited state of the guest material 142 can be increased. Note that the exciplex generated in the light-emitting layer 140 has the characteristic that the singlet excitation energy level and the triplet excitation energy level are close to each other. Therefore, by overlapping the emission spectrum of the exciplex and the absorption band that appears on the longest wavelength side (low energy side) of the guest material 142, it is also possible to facilitate the energy transfer from the triplet excitation energy level of the exciplex to the triplet excitation energy level of the guest material 142. Furthermore, in order to facilitate the energy transfer from the singlet excitation energy level of the exciplex to the triplet excitation energy level of the guest material 142, it is preferable that the emission spectrum of the exciplex and the absorption band that appears on the longest wavelength side (low energy side) of the absorption spectrum of the guest material 142 overlap. By establishing such a relationship between the emission spectrum and the absorption spectrum, the generation efficiency of the triplet excited state of the guest material 142 can be increased. Note that the exciplex generated in the light-emitting layer 140 has the characteristic that the singlet excitation energy level and the triplet excitation energy level are close to each other. Therefore, by overlapping the emission spectrum of the exciplex and the absorption band that appears on the longest wavelength side (low energy side) of the guest material 142, it is also possible to facilitate the energy transfer from the triplet excitation energy level of the exciplex to the triplet excitation energy level of the guest material 142. Furthermore, in order to facilitate the energy transfer from the singlet excitation energy level of the exciplex to the triplet excitation energy level of the guest material 142, it is preferable that the emission spectrum of the exciplex and the absorption band that appears on the longest wavelength side (low energy side) of the absorption spectrum of the guest material 142 overlap. By establishing such a relationship between the emission spectrum and the absorption spectrum, the generation efficiency of the triplet excited state of the guest material 142 can be increased. Note that the exciplex generated in the light-emitting layer 140 has the characteristic that the singlet excitation energy level and the triplet excitation energy level are close to each other. Therefore, by overlapping the emission spectrum of the exciplex and the absorption band that appears on the longest wavelength side (low energy side) of the guest material 142, it is also possible to facilitate the energy transfer from the triplet excitation energy level of the exciplex to the triplet excitation energy level of the guest material 142. Furthermore, in order to facilitate the energy transfer from the singlet excitation energy level of the exciplex to the triplet excitation energy level of the guest material 142, it is preferable that the emission spectrum of the exciplex and the absorption band that appears on the longest wavelength side (low energy side) of the absorption spectrum of the guest material 142 overlap. By establishing such a relationship between the emission spectrum and the absorption spectrum, the generation efficiency of the triplet excited state of the guest material 142 can be increased. Note that the exciplex generated in the light-emitting layer 140 has the characteristic that the singlet excitation energy level and the triplet excitation energy level are close to each other. Therefore, by overlapping the emission spectrum of the exciplex and the absorption band that appears on the longest wavelength side (low energy side) of the guest material 142, it is also possible to facilitate the energy transfer from the triplet excitation energy level of the exciplex to the triplet excitation energy level of the guest material 142. Furthermore, in order to facilitate the energy transfer from the singlet excitation energy level of the exciplex to the triplet excitation energy level of the guest material 142, it is preferable that the emission spectrum of the exciplex and the absorption band that appears on the longest wavelength side (low energy side) of the absorption spectrum of the guest material 142 overlap. By establishing such a relationship between the emission spectrum and the absorption spectrum, the generation efficiency of the triplet excited state of the guest material 142 can be increased. Note that the exciplex generated in the light-emitting layer 140 has the characteristic that the singlet excitation energy level and the triplet excitation energy level are close to each other. Therefore, by overlapping the emission spectrum of the exciplex and the absorption band that appears on the longest wavelength side (low energy side) of the guest material 142, it is also possible to facilitate the energy transfer from the triplet excitation energy level of the exciplex to the triplet excitation energy level of the guest material 142. Furthermore, in order to facilitate the energy transfer from the singlet excitation energy level of the exciplex to the triplet excitation energy level of the guest material 142, it is preferable that the emission spectrum of the exciplex and the absorption band that appears on the longest wavelength side (low energy side) of the absorption spectrum of the guest material 142 overlap. By establishing such a relationship between the emission spectrum and the absorption spectrum, the generation efficiency of the triplet excited state of the guest material 142 can be increased. Note that the exciplex generated in the light-emitting layer 140 has the characteristic that the singlet excitation energy level and the triplet excitation energy level are close to each other. Therefore, by overlapping the emission spectrum of the exciplex and the absorption band that appears on the longest wavelength side (low energy side) of the guest material 142, it is also possible to facilitate the energy transfer from the triplet excitation energy level of the exciplex to the triplet excitation energy level of the guest material 142. Note that the exciplex generated in the light-emitting layer 140 has the characteristic that the singlet excitation energy level and the triplet excitation energy level are close to each other. Therefore, by overlapping the emission spectrum of the exciplex and the absorption band that appears on the longest wavelength side (low energy side) of the guest material 142, it is also possible to facilitate the energy transfer from the triplet excitation energy level of the exciplex to the triplet excitation energy level of the guest material 142. Note that the exciplex generated in the light-emitting layer 140 has the characteristic that the singlet excitation energy level and the triplet excitation energy level are close to each other. Therefore, by overlapping the emission spectrum of the exciplex and the absorption band that appears on the longest wavelength side (low energy side) of the guest material 142, it is also possible to facilitate the energy transfer from the triplet excitation energy level of the exciplex to the triplet excitation energy level of the guest material 142. Note that the exciplex generated in the light-emitting layer 140 has the characteristic that the singlet excitation energy level and the triplet excitation energy level are close to each other. Therefore, by overlapping the emission spectrum of the exciplex and the absorption band that appears on the longest wavelength side (low energy side) of the guest material 142, it is also possible to facilitate the energy transfer from the triplet excitation energy level of the exciplex to the triplet excitation energy level of the guest material 142. Note that the exciplex generated in the light-emitting layer 140 has the characteristic that the singlet excitation energy level and the triplet excitation energy level are close to each other. Therefore, by overlapping the emission spectrum of the exciplex and the absorption band that appears on the longest wavelength side (low energy side) of the guest material 142, it is also possible to facilitate the energy transfer from the triplet excitation energy level of the exciplex to the triplet excitation energy level of the guest material 142.

[0102] <Material> Next, the details of the components of the light-emitting device according to one embodiment of the present invention will be described below.

[0103] ≪Light-emitting layer≫ In the light-emitting layer 140, the host material 141 is present in the largest amount by weight, and the guest material 142 (Phosphorescent material) is dispersed in the host material 141. The T1 level of the host material 141 ( organic compounds 141_1 and organic compounds 141_2) of the light-emitting layer 140 is preferably higher than the T1 level of the guest material (guest material 142) of the light-emitting layer 140.

[0104] As the organic compound 141_1, a material with higher electron transportability than hole transportability can be used, and it is preferably a material having an electron mobility of 1×10 cm -6 / Vs or more. As a material that easily accepts electrons (a material having electron transportability), compounds having a π-electron-deficient heteroaromatic ring skeleton such as nitrogen-containing heteroaromatic compounds 2 , and zinc or aluminum-based 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, benzimidazole derivatives, quinoxaline derivatives, dibenzo , quinoxaline derivatives, phenanthroline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, triazine derivatives, and other compounds can be mentioned. , quinoxaline derivatives, phenanthroline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, triazine derivatives, and other compounds can be mentioned. Specifically, for example, tris(8-quinolinolato)aluminum(III) (abbreviation: A lq), tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviation: Al mq3), bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation : BeBq2), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)a luminum(III) (abbreviation: BAlq), bis(8-quinolinolato)zinc(II) (abbreviation

[0105] : Znq), etc., and metal complexes having a quinoline skeleton or a benzoquinoline skeleton can be mentioned. luminum(III) (abbreviation: BAlq), bis(8-quinolinolato)zinc(II) (abbreviation : Znq), etc., and metal complexes having a quinoline skeleton or a benzoquinoline skeleton can be mentioned. : BeBq2), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)a luminum(III) (abbreviation: BAlq), bis(8-quinolinolato)zinc(II) (abbreviation : Znq), etc., and metal complexes having a quinoline skeleton or a benzoquinoline skeleton can be mentioned. can also be used. In addition, other metal complexes having oxazole-based or thiazole-based ligands such as bis[2-(2-benzoxazolyl)phenolato]zinc(II) ( abbreviation: ZnPBO), bis[2-(2-benzothiazolyl)phenolato]zinc(II) ( abbreviation: ZnBTZ), etc. can also be used. Further, in addition to metal complexes, 2-(4-biphenylyl)-5 -(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD) and 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiaz ol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3, 4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11) 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)- 1,2,4-triazole (abbreviation: TAZ), 9-[4-(4,5-diphenyl-4H- 1,2,4-triazol-3-yl)phenyl]-9H-carbazole (abbreviation: CzT AZ1), 2,2’,2’’-(1,3,5-benzenetriyl)tris(1-phenyl -1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophene- 4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBI m-II), bathophenanthroline (abbreviation: BPhen), bathocuproine (abbreviation: B CP), etc. and heterocyclic compounds such as 2-[3-(dibenzothiophene-4-yl)phenyl] dibenz[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3’-( dibenzothiophene-4-yl)biphenyl-3-yl]dibenz[f,h]quinoxali ne (abbreviation: 2mDBTPDBq-III), etc. can also be used. N (abbreviation: 2mDBTBPDBq-II), 2-[3’-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]dibenzo [f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzo thiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDB TPDBq-II), and 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo [f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 2-[3-(3, 9’-bi-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzCzPDBq), 4,6-bis[3-(phenanthren-9-yl)f enyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-diben zothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6- bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mC zP2Pm) and other heterocyclic compounds having a diazine skeleton, 2-{4-[3-(N-phe nyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}- 4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn) and other heterocyclic compounds having a tria zine skeleton, 3,5-bis[3-(9H-carbazol-9-yl )phenyl]pyridine (abbreviation: 35DCzPPy), 1,3,5-tri[3-(3-pyr )phenyl]benzene (abbreviation: TmPyPB) and other heterocyclic compounds having a pyridine skeleton, 4,4’-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: ), and other heterocyclic compounds having a pyridine skeleton, 4,4’-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: ) Heteroaromatic compounds such as BzOs) can also be used. Among the above-mentioned heterocyclic compounds also, heterocyclic compounds having a triazine skeleton, a diazine (pyrimidine, pyrazine, pyridazine) skeleton, or a pyridine skeleton are preferable because they are stable and have good reliability. In addition, the heterocyclic compounds having such a skeleton have high electron transport properties and also contribute to reducing the driving voltage. Also, 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-dioctylfluorene-2,7-diyl)-co-(2,2'-bipyridine -6,6'-diyl)] (abbreviation: PF-BPy) can also be used. The substances described here mainly have an electron mobility of 1×10 cm -6 / Vs or more. As long as the substance has higher electron transport properties than holes, substances other than the above can be used. 2 substances. It doesn't matter.

[0106] As the organic compound 141_2, a combination that can form an exciplex with the organic compound 141_1 is preferable. Specifically, it preferably has a highly donor-like skeleton such as a π-electron-excessive heterocyclic aromatic ring skeleton or an aromatic amine skeleton. As a compound having a π-excessive heterocyclic aromatic ring skeleton, heteroaromatic compounds such as dibenzothiophene derivatives, dibenzofuran derivatives, and carbazole derivatives can be mentioned. In this case, the emission peak of the exciplex formed by the organic compound 141_1 and the organic compound 141_ 2 is the absorption of the triplet ML CT (Metal to Ligand Charge Transfer) transition of the guest material 142 (phosphorescent material). A belt, more specifically, the organic compound 141_1 and the organic compound 141_2 are preferably selected so as to overlap with the absorption band on the longest wavelength side, and the guest material 142 (phosphorescent material). The organic compound 141_2 and the guest material 142 (phosphorescent material) are preferably selected. As a result, a light-emitting device with a dramatically improved luminous efficiency can be obtained. However, when a thermally activated delayed fluorescence material is used instead of the phosphorescent material, the absorption band on the longest wavelength side is preferably the singlet absorption band. In the case of using a thermally activated delayed fluorescence material instead of the phosphorescent material, the absorption band on the longest wavelength side is preferably the singlet absorption band. In the case of using a thermally activated delayed fluorescence material instead of the phosphorescent material, the absorption band on the longest wavelength side is preferably the singlet absorption band.

[0107] In addition, as the organic compound 141_2, the following hole-transporting materials can be used.

[0108] 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 cm / 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. ×10 -6 cm 2 / Vs or more is preferred. Specifically, aromatic amines, carbazole derivatives, aromatic hydrocarbons, stilbene derivatives, etc. can be used. Further, the hole-transporting material may be a polymer compound. Specifically, aromatic amines, carbazole derivatives, aromatic hydrocarbons, stilbene derivatives, etc. can be used. Further, the hole-transporting material may be a polymer compound. Specifically, aromatic amines, carbazole derivatives, aromatic hydrocarbons, stilbene derivatives, etc. can be used. Further, the hole-transporting material may be a polymer compound.

[0109] As these materials with high hole transportability, specifically, as aromatic amine compounds, N,N'-di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), N,N'-bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviation: DNTPD), 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B), etc. can be mentioned. N,N'-di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), N,N'-bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviation: DNTPD), 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B), etc. can be mentioned. 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), N,N'-bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviation: DNTPD), 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B), etc. can be mentioned. N,N'-bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviation: DNTPD), 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B), etc. can be mentioned. N,N'-bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviation: DNTPD), 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B), etc. can be mentioned. 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B), etc. can be mentioned. 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B), etc. can be mentioned. etc. can be mentioned.

[0110] 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 azole-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1) etc. can be mentioned.

[0111] In addition, as the carbazole derivative, among others, 4,4'-di(N-carbazolyl)biphe nyl (abbreviation: CBP), 1,3,5-tris[4-(N-carbazolyl)phenyl]ben zene (abbreviation: TCPB), 9-[4-(10-phenyl-9-anthryl)phenyl]- 9H-carbazole (abbreviation: CzPA), 1,4-bis[4-(N-carbazolyl)phenyl nyl]-2,3,5,6-tetraphenylbenzene etc. can be used.

[0112] 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)anthracene DPPA, 2-tert-butyl-9,10-bis(4-phenylphenyl) 9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDBA), Helical (abbreviation: DNA), 9,10-diphenylanthracene (abbreviation: DPAnth), 2-tert-Butylanthracene (abbreviation: t-BuAnth), 9,10-bis(4- Methyl-1-naphthyl)anthracene (abbreviation: DMNA), 2-tert-butyl-9, 10-Bis[2-(1-naphthyl)phenyl]anthracene, 9,10-bis[2-(1 -naphthyl)phenyl]anthracene, 2,3,6,7-tetramethyl-9,10-di( 1-naphthyl)anthracene, 2,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene 9,9'-bianthryl, 10,10'-diphenyl-9,9'- Bianthryl, 10,10'-bis(2-phenylphenyl)-9,9'-bianthryl , 10,10'-bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9' -Bianthryl, anthracene, tetracene, rubrene, perylene, 2,5,8,11- Tetra(tert-butyl)perylene, etc. In addition, pentacene, coro Years and years can also be used. In this way, 1×10 -6 cm 2 Hole mobility above / Vs It is more preferable to use an aromatic hydrocarbon having 14 to 42 carbon atoms.

[0113] The aromatic hydrocarbon may have a vinyl skeleton. Examples of aromatic hydrocarbons include 4,4'-bis(2,2-diphenylvinyl)biphenyl. (Abbreviation: DPVBi), 9,10-bis[4-(2,2-diphenylvinyl)phenyl] anthracene (Abbreviation: DPVPA), etc. can be mentioned.

[0114] Also, poly(N-vinylcarbazole) (Abbreviation: PVK), poly(4-vinyltriphenyl amine) (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. of polymer compounds can also be used.

[0115] Furthermore, as materials with high hole transport properties, for example, 4,4’-bis[N-(1-naphthyl )-N-phenylamino]biphenyl (Abbreviation: NPB or α-NPD), N,N’- bis(3-methylphenyl)-N,N’-diphenyl-[1,1’-biphenyl]-4, 4’-diamine (Abbreviation: TPD), 4,4’,4’’-tris(carbazol-9-yl )triphenylamine (Abbreviation: TCTA), 4,4’,4’’-tris[N-(1-naph thyl)-N-phenylamino]triphenylamine (Abbreviation: 1’-TNATA), 4,4 ’,4’’-tris(N,N-diphenylamino)triphenylamine (Abbreviation: TDAT A), 4,4’,4’’-tris[N-(3-methylphenyl)-N-phenylamino] triphenylamine (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: BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenyl amine (abbreviation: mBPAFLP), N-(9,9-dimethyl-9H-fluoren-2 -yl)-N-{9,9-dimethyl-2-[N'-phenyl-N'-(9,9-dimethyl -9H-fluoren-2-yl)amino]-9H-fluoren-7-yl}phenylamine (abbreviation: DFLADFL), N-(9,9-dimethyl-2-diphenylamino-9H- fluoren-7-yl)diphenylamine (abbreviation: DPNF), 2-[N-(4-diphe nylaminophenyl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: DPASF), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl) triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9- phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: 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: PCBN BB), 4-phenyldiphenyl-(9-phenyl-9H-carbazol-3-yl)a mine (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 l)benzene-1,3,5-triamine (abbreviation: PCA3B), N-(4-biphenyl) -N-(9,9-Dimethyl-9H-fluoren-2-yl)-9-phenyl-9H-carb azole-3-amine (abbreviation: PCBiF), N-(1,1'-biphenyl-4-yl) -N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-di methyl-9H-fluoren-2-amine (abbreviation: PCBBiF), 9,9-dimethyl-N -phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]f luoren-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl -9H-carbazol-3-yl)phenyl]spiro-9,9'-bifluorene-2-a mine (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-9,9- dimethylfluorene-2,7-diamine (abbreviation: YGA2F) and other aromatic amine compounds etc. can be used. Also, 3-[4-(1-naphthyl)-phenyl]-9-phenyl -9H-carbazole (abbreviation: PCPN), 3-[4-(9-phenanthryl)-phen yl]-9-phenyl-9H-carbazole (abbreviation: PCPPn), 3,3'-bis(9 -phenyl-9H-carbazole) (abbreviation: PCCP), 1,3-bis(N-carbazolyl l)benzene (abbreviation: mCP), 3,6-bis(3,5-diphenylphenyl)-9-f Enilcarbazole (abbreviation: CzTP), 3,6-di(9H-carbazol-9-yl) -9-phenyl-9H-carbazole (abbreviation: PhCzGI), 2,8-di(9H-carb azol-9-yl)-dibenzothiophene (abbreviation: Cz2DBT), 4-{3-[3- (9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran( abbreviation:mmDBFFLBi-II), 4,4’,4’’-(benzene-1,3,5-tri yl)tri(dibenzofuran) (abbreviation: DBF3P-II), 1,3,5-tri(dibenz othiophen-4-yl)-benzene (abbreviation: DBT3P-II), 2,8-diphenyl -4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiop ene (abbreviation: DBTFLP-III), 4-[4-(9-phenyl-9H-fluoren- 9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV) 、4-[3-(triphenylene-2-yl)phenyl]dibenzothiophene (abbreviation: mD BTPTp-II) and other amine compounds, carbazole compounds, thiophene compounds, furan compounds, fluorene compounds, triphenylene compounds, phenanthrene compounds, etc. can be used. Among the above-mentioned compounds, compounds having a pyrrole skeleton, a furan skeleton, a thiophene skeleton, an aromatic amine skeleton are stable and have good reliability, and are preferable. Also, compounds having such a skeleton have high hole transportability and contribute to reducing the driving voltage.

[0116] As the guest material 142 (phosphorescent material), iridium, rhodium, or platinum-based organic metal complexes, or metal complexes can be mentioned. Among them, organic iridium complexes, for example, iridium An orthometal complex is preferred. As the ligand for orthometalation, 4H-triazole ligand, 1H-triazole ligand, imidazole ligand, pyridine ligand, pyrimidine ligand, pyrazine ligand, or isoquinoline ligand, etc. can be mentioned. As the metal complex therein, a platinum complex having a porphyrin ligand, etc. can be mentioned.

[0117] In addition, as the guest material 142 (phosphorescent material), it has a LUMO level lower than the LUMO level of the organic compound 141_1 and a HOMO level lower than the HOMO level of the organic compound 141_2. It is preferable to select the organic compound 141_1, the organic compound 141_2, and the guest material 14 2 (phosphorescent material) accordingly. Thereby, a light-emitting element with high luminous efficiency and low-voltage driving can be obtained.

[0118] Examples of substances having a light-emitting peak in blue or green include, for example, tris{2-[5-(2 -methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triaz ol-3-yl-κN2]phenyl-κC}iridium(III) (abbreviation: Ir(mpp tz-dmp)3), tris(5-methyl-3,4-diphenyl-4H-1,2,4-t riazolato)iridium(III) (abbreviation: Ir(Mptz)3), tris[4-(3- biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazolato]i ridium(III) (abbreviation: Ir(iPrptz-3b)3), tris[3-(5-bip henyl)-5-isopropyl-4-phenyl-4H-1,2,4-triazolato]iridi um(III) (abbreviation: Ir(iPr5btz)3), etc., having a 4H-triazole skeleton Organometallic iridium complexes having, tris[3-methyl-1-(2-methylphenyl) -5-phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviation: Ir (Mptz1-mp)3), tris(1-methyl-5-phenyl-3-propyl-1H- 1,2,4-triazolato)iridium(III) (abbreviation: Ir(Prptz1-Me) 3) and other organometallic iridium complexes having a 1H-triazole skeleton, fac-tri s[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]i ridium(III) (abbreviation: Ir(iPrpmi)3), tris[3-(2,6-dimethyl lphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(I II) (abbreviation: Ir(dmpimpt-Me)3) and other organometallic iridium complexes having an imidazole skeleton, bis[2-(4’,6’-difluorophenyl)pyridinato- N,C iridium(III) tetrakis(1-pyrazolyl)borate (abbreviation: FI 2’ r6), bis[2-(4’,6’-difluorophenyl)pyridinato-N,C iri 2’ dium(III) picolinate (abbreviation: FIrpic), bis{2-[3’,5’-bis (trifluoromethyl)phenyl]pyridinato-N,C (trifluoromethyl)phenyl]pyridinato-N,C 2’}iridium(III) pico linate (abbreviation: Ir(CF3ppy)2(pic)), bis[2-(4’,6’-dif luorophenyl)pyridinato-N,C 2’ iridium(III) acetylacetonate (abbreviation: FIr(acac)) and other organometallic iridium complexes having a phenylpyridine derivative having an electron-withdrawing group as a ligand. Among those described above, 4H-triazole A nitrogen-containing five-membered heterocyclic skeleton such as a skeleton, 1H-triazole skeleton, and imidazole skeleton The organometallic iridium complex having is particularly preferable because it has a high triplet excitation energy and is excellent in reliability and luminescence efficiency.

[0119] In addition, as a substance having a luminescence peak in green or yellow, 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 lu-2-[6-(2,6-dimethylphenyl)-4-pyrimidinyl-κN3]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, and (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazina​ Tris(5-isopropyl-3-methyl-2-phenylpyrazinato-N,C2‘)iridium(III) (abbreviation: Ir(mppr-Me)2(acac)), (acetyl acetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium (III) (abbreviation: Ir(mppr-iPr)2(acac)) and other organometallic iridium complexes having a pyrazine skeleton, tris(2-phenylpyridinato-N,C2‘)iridium(III) (abbreviation: Ir(ppy)3), bis(2-phenylpyridinato-N,C2‘ 2’ ) iridium(III) acetylacetonate (abbreviation: Ir(ppy)2(acac)), bis(benzo[h]quinolinato)iridium(III) acetylacetonate ,C 2’ (abbreviation: Ir(bzq)2(acac)), tris(benzo[h]quinolinato)iridium(III) (abbreviation: Ir(bzq)3), tris(2-phenylquinolinato-N,C2‘ (abbreviation: Ir(pq)3), bis(2-phenylquinolinato-N,C2‘ iridium(III) acetylacetonate (abbreviation: Ir(pq)2(acac)) and other organometallic iridium complexes having a pyridine skeleton, bis(2,4-difluorophenyl-1,3-oxazolato-N,C2‘)iridium(III) acetylacetonate 2 ’ (abbreviation: Ir(dpo)2(acac)), bis{2-[4‘-(perfluorophenyl)phenyl]pyridinato-N,C2‘}iridium(III) acetylacetonate -N,C 2’ (abbreviation: Ir(p-PF-ph)2(acac)), bis(2-phenylbenzothiazolato-N,C2‘ (abbreviation: Ir(bt)2(acac)) and other organometallic iridium complexes having a pyridine skeleton bis(2,4-difluorophenyl-1,3-oxazolato-N,C2‘)iridium(III) acetylacetonate 2’ (abbreviation: Ir(dpo)2(acac)), bis{2-[4‘-(perfluorophenyl)phenyl]pyridinato-N,C2‘}iridium(III) acetylacetonate (abbreviation: Ir(p-PF-ph)2(acac)), bis(2-phenylbenzothiazolato-N,C2‘ (abbreviation: Ir(bt)2(acac)) 2’}{iridium(III) acetylacetonate (abbreviation: Ir(p-PF-ph)2(acac)), bis(2-phenylbenzothiazolato-N,C2‘ (abbreviation: Ir(bt)2(acac)) -N,C 2’ (abbreviation: Ir(bt)2(acac)) In addition to organometallic iridium complexes such as cac), rare earth metal complexes such as tris(acetylacetonato)(monophen antroline)terbium(III)(abbreviation: Tb(acac)3(Phen)) are also included. Among those mentioned above, organometallic iri dium complexes having a pyrimidine skeleton are particularly preferable because they are remarkably excellent in reliability and luminescence efficiency.

[0120] In addition, as substances having a luminescence peak in yellow or red, for example, (diisobutyryl methanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(II I)(abbreviation: Ir(5mdppm)2(dibm)), bis[4,6-bis(3-methyl phenyl)pyrimidinato](dipivaloylmethanato)iridium(III)(abbreviation: Ir (5mdppm)2(dpm)), bis[4,6-di(naphthalen-1-yl)pyrimidi nato](dipivaloylmethanato)iridium(III)(abbreviation: Ir(d1npm)2( dpm)) and other organometallic iridium complexes having a pyrimidine skeleton, or (acetylacet tonato)bis(2,3,5-triphenylpyrazinato)iridium(III)(abbreviation: I r(tppr)2(acac)), bis(2,3,5-triphenylpyrazinato)(dip ivaloylmethanato)iridium(III)(abbreviation: Ir(tppr)2(dpm)), ( acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]i ridium(III)(abbreviation: Ir(Fdpq)2(acac)) and other organometallic iridium complexes having a pyrazine skeleton, or tris(1-phenylisoquinolinato-N,C ) 2’ ) iridium(III)(abbreviation: Ir(piq)3), bis(1-phenylisoquinolinato -N,C 2’)Iridium(III) acetylacetonate (abbreviation: Ir(piq)2( acac)), in addition to organometallic iridium complexes having a pyridine skeleton, 2,3,7, 8,12,13,17,18 - octaethyl - 21H,23H - porphyrin platinum(II )(abbreviation: PtOEP) and other platinum complexes, and 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 etonato](monophenanthroline) europium(III) (abbreviation: Eu(TTA)3( Phen)) and other rare - earth metal complexes can be mentioned. Among those described above, organometallic iridium complexes having a pyrimidine skeleton are particularly preferable because they are outstanding in terms of reliability and luminescence efficiency. Also, organometallic iridium complexes having a pyrazine skeleton can obtain red luminescence with good chromaticity. Moreover, among the above - mentioned iridium complexes, organometallic iridium complexes having a pyrimidine skeleton or a pyrazine skeleton are suitable for one aspect of the present invention because they have a high electron - accepting property of the ligand and are likely to have a low LUMO level. Also, compounds (for example, iridium complexes) having an electron - withdrawing substituent such as a halogen group like a fluoro group or a cyano group are also suitable because they are likely to have a low LUMO level. As the light - emitting material contained in the light - emitting layer 140, any material that can convert triplet excitation energy into light may be used. As the material that can convert triplet excitation energy into light, in addition to phosphorescent materials, thermally activated delayed fluorescence (Thermally activated delayed fluorescence)

[0121] In addition, among the above - mentioned iridium complexes, organometallic iridium complexes having a pyrimidine skeleton or a pyrazine skeleton have a high electron - accepting property of the ligand and are likely to have a low LUMO level, so they are suitable for one aspect of the present invention. Also, compounds (for example, iridium complexes) having an electron - withdrawing substituent such as a halogen group like a fluoro group or a cyano group are also suitable because they are likely to have a low LUMO level. Moreover, among the above - mentioned iridium complexes, organometallic iridium complexes having a pyrimidine skeleton or a pyrazine skeleton are suitable for one aspect of the present invention because they have a high electron - accepting property of the ligand and are likely to have a low LUMO level. Also, compounds (for example, iridium complexes) having an electron - withdrawing substituent such as a halogen group like a fluoro group or a cyano group are also suitable because they are likely to have a low LUMO level. As the light - emitting material contained in the light - emitting layer 140, any material that can convert triplet excitation energy into light may be used. As the material that can convert triplet excitation energy into light, in addition to phosphorescent materials, thermally activated delayed fluorescence (Thermally activated delayed fluorescence) is also suitable because it is likely to have a low LUMO level.

[0122] As the light - emitting material contained in the light - emitting layer 140, any material that can convert triplet excitation energy into light may be used. As the material that can convert triplet excitation energy into light, in addition to phosphorescent materials, thermally activated delayed fluorescence (Thermally activated delayed fluorescence) In addition to phosphorescent materials, thermally activated delayed fluorescence (Thermally activated delayed Examples include fluorescence: thermally activated delayed fluorescence (TADF) materials. Therefore, with respect to the part described as phosphorescent materials, it may be read as thermally activated delayed fluorescence materials. Note that a thermally activated delayed fluorescence material is a material having a function of converting energy from a triplet excited state to a singlet excited state by reverse intersystem crossing because the difference between the triplet excited energy level and the singlet excited energy level is small. Therefore, upconversion (reverse intersystem crossing) from the triplet excited state to the singlet excited state is possible with a small amount of thermal energy, and efficient emission (fluorescence) from the singlet excited state can be exhibited. Further, as conditions for efficiently obtaining thermally activated delayed fluorescence, the energy difference between the triplet excited energy level and the singlet excited energy level is preferably greater than 0 eV and 0.2 eV or less, more preferably greater than 0 eV and 0.1 eV or less. When the thermally activated delayed fluorescence material is composed of one type of material, for example, the following materials can be used. 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 protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride When the thermally activated delayed fluorescence material is composed of one type of material, for example, the following materials can be used. 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 protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride When the thermally activated delayed fluorescence material is composed of one type of material, for example, the following materials can be used. 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 protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride When the thermally activated delayed fluorescence material is composed of one type of material, for example, the following materials can be used. 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 protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride When the thermally activated delayed fluorescence material is composed of one type of material, for example, the following materials can be used.

[0123] 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 protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride 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 protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride

[0124] 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 protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride 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 protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride 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 protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride 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 protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride 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 protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride 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 protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride 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 protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride Complex (SnF2(Copro III-4Me)), octaethylporphyrin-fluoride Tin complex (SnF2(OEP)), etioporphyrin-tin fluoride complex (SnF2(E tio I)), octaethylporphyrin-platinum chloride complex (PtCl2OEP), etc. are exemplified .

[0125] In addition, as a thermally activated delayed fluorescence material composed of a single material, a heterocyclic compound having a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring can also be used. Specifically it is, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3- a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazolo l-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PC CzPTzn), 2-[4-(10H-phenoxazine-10-yl)phenyl]-4, 6-diphenyl-1,3,5-triazine (abbreviation: PXZ-TRZ), 3-[4-(5- phenyl-5,10-dihydrophenazine-10-yl)phenyl]-4,5-diphenyl l-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl- 9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN) (abbreviation: ACRSA), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), 10-phenyl-10H,10’H-spiro[acridine -9,9’-anthracene]-10’-one (abbreviation: ACRSA), etc. are exemplified. The complex heterocyclic compound has a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring, so electrons ​It is preferable to have high transportability and hole transportability. Among them, a skeleton having a π-electron-deficient heteroaromatic ring Among them, a diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), or tri azine skeleton is preferable because it is stable and has good reliability. Also, among the skeletons having a π-electron-excessive heteroaromatic ring Among them, an acridine skeleton, a phenoxazine skeleton, a thiophene skeleton, a furan skeleton and a pyrrole skeleton are preferable because they are stable and have good reliability, and it is preferable to have any one or more selected from among these skeletons. Note that as the pyrrole skeleton, an indole skeleton, a carbazole skeleton, and a 3-(9-phenyl-9H-carbazol-3-yl)- 9H-carbazole skeleton are particularly preferable. Note that a substance in which a π-electron-excessive heteroaromatic ring and a π-electron-deficient type heteroaromatic ring are directly bonded has both strong donor properties of the π-electron-excessive heteroaromatic ring and acceptor properties of the π-electron-deficient type heteroaromatic ring, and the difference in energy levels between the singlet excited state and the triplet excited state is small, so it is particularly preferable. The light-emitting layer 140 can also be composed of two or more layers. For example, when the first light-emitting layer and the second light-emitting layer are laminated in order from the hole transport layer side to form the light-emitting layer 140, a substance having hole transportability is used as the host material of the first

[0126] light-emitting layer, and a substance having electron transportability is used as the host material of the second light-emitting layer and the like. Also, 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 the same color of light or materials having a function of emitting different colors of light. By using light-emitting materials having functions of emitting mutually different colors of light in the two light-emitting layers respectively, a plurality of emissions can be obtained simultaneously. In particular, the two light-emitting layers exhibit light of the same color or different colors, and may be materials having a function of emitting different colors of light. By using light-emitting materials having functions of emitting mutually different colors of light in the two light-emitting layers respectively, a plurality of emissions can be obtained simultaneously. In particular, the two light-emitting layers exhibit light of the same color or different colors, and may be materials having a function of emitting different colors of light. By using light-emitting materials having functions of emitting mutually different colors of light in the two light-emitting layers It is preferable to select a light-emitting material to be used in each light-emitting layer so that white light is obtained by the light emission.

[0127] Also, in the light-emitting layer 140, materials other than the host material 141 and the guest material 142 may be included.

[0128] Note that the light-emitting layer 140 can be formed by a method such as a vapor deposition method (including a vacuum vapor deposition method), an inkjet method, a coating method, a gravure printing method, etc. Also, in addition to the materials described above, it may have an inorganic compound or a polymer compound (such as an oligomer, a dendrimer, a polymer, etc.) such as a quantum dot. may be included.

[0129] ≪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, for example, by a transition metal oxide, a phthalocyanine derivative, or an aromatic amine. Examples of the transition metal oxide include molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, and manganese oxide. Examples of the phthalocyanine derivative include phthalocyanine and metal phthalocyanine. Examples of the aromatic amine 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.

[0130] As the hole injection layer 111, a layer having a composite material of a hole transporting material and a material showing electron accepting properties with respect to this can also be used. Alternatively, a layer containing a material showing electron accepting properties and a positive ​ A stack of layers 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 materials exhibiting electron-accepting properties include organic acceptors such as quinodimethane derivatives, chloranil derivatives, and hexaazatriphenylene derivatives. Specifically, compounds having an electron-withdrawing group (such as a halogen group or a cyano group) such as 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT-CN), etc. can be mentioned. In addition, 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 preferred because it is stable in the air, has low hygroscopicity, and is easy to handle. For the hole-transporting material, a material with higher hole-transporting property than electrons can be used, and it is preferably a material having a hole mobility of 1×10 cm / Vs or more. Specifically, aromatic amines, carbazole derivatives, aromatic hydrocarbons, stilbene derivatives, etc. mentioned as hole-transporting materials that can be used in the light-emitting layer 140 can be used. Also, the hole-transporting material may be a polymer compound. ≪Hole Transport Layer≫ The hole transport layer 112 is a layer containing a hole-transporting material, and as an example of the material of the hole injection layer 111,

[0131] ×10 -6 cm 2 / Vs or more.

[0132] ​​​​​​​​The hole transporting layer 112 is connected to the hole injection layer 111. Since the hole injection layer 111 has a function of transporting the injected holes to the light emitting layer 140, Highest Occupied Molecular Orbital (H It is preferable for the HOMO level to be the same as or close to the OMO level.

[0133] Also, 1×10 -6 cm 2 It is preferable that the material has a hole mobility of at least 1 / Vs. However, other substances may be used as long as they have a higher hole transporting property than an electron transporting property. The layer containing a substance having a high hole transporting property may be a single layer or a double layer of the above substance. More than one layer may be laminated.

[0134] ≪Electron transport layer≫ The electron transport layer 118 is connected to the other of the pair of electrodes (electrode 101 or The material has a function of transporting electrons injected from the electrode 102 to the light-emitting layer 140. A material with a higher electron transport capacity than holes can be used as the -6 cm 2 It is preferable that the material has an electron mobility of 100 / Vs or more. As materials with electron transport properties, π-electron-deficient compounds such as nitrogen-containing heteroaromatic compounds are Heteroaromatics and metal complexes can be used. Specifically, the light-emitting layer 140 can be The quinoline ligand, benzoquinoline ligand, and oxalate ligand mentioned above as electron transport materials that can Metal complexes having zole or thiazole ligands, oxadiazole derivatives, Triazole derivatives, benzimidazole derivatives, quinoxaline derivatives, dibenzoquinoxaline Sarine derivatives, phenanthroline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, triazine derivatives, etc. can be mentioned. Further, 1×10 -6 cm 2 / Vs or more It is preferable that the substance has an electron mobility. Note that any substance other than the above may be used as the electron transport layer as long as it has higher electron transportability than holes. Further, the electron transport layer 1 18 may be not only a single layer but also two or more layers of the above substances laminated.

[0135] Further, a layer for controlling the movement of electron carriers may be provided between the electron transport layer 118 and the light emitting layer 140. 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 has a great effect on suppressing problems (for example, reduction of element lifetime) caused by electrons passing through the light emitting layer.

[0136] ≪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, Group 1 metals, Group 2 metals, or their oxides, halides carbonates, etc. can be used. Further, a composite material of the electron transport material shown above and a material showing electron donating property can also be used. Examples of the material showing electron donating property include Group 1 metals, Group 2 metals, or their oxides. Specifically Group 1 metals, Group 2 metals, or their oxides can be mentioned. Specifically lithium fluoride (LiF), sodium fluoride (NaF), cesium fluoride (CsF ), calcium fluoride (CaF2), lithium oxide (LiO x ​​​​​​) and other alkaline gold Metals, alkaline earth metals, or compounds thereof can be used. A rare earth metal compound such as ruthenium (ErF3) can be used. An electride may be used for 119. The electride may be, for example, calcium. Examples include a material in which electrons are highly concentrated in a mixed oxide of aluminum and ruthenium. The injection layer 119 may be made of a material that can be used in the electron transport layer 118 .

[0137] In addition, the electron injection layer 119 is made of a composite material obtained by mixing an organic compound and an electron donor. Such composite materials may be made by adding electrons to an organic compound via an electron donor. In this case, the organic compound is It is preferable that the material has excellent transport properties for the generated electrons. Specifically, for example, the above-mentioned The material constituting the electron transport layer 118 (metal complex, heteroaromatic compound, etc.) can be used. The electron donor may be any substance that exhibits electron donating properties to organic compounds. For the metal, alkali metals, alkaline earth metals and rare earth metals are preferred, and lithium, sodium , cesium, magnesium, calcium, erbium, ytterbium, etc. In addition, alkali metal oxides and alkaline earth metal oxides are preferred, and lithium oxide, calcium oxide, etc. Examples of the oxides include magnesium oxide, barium oxide, etc. A base can also be used. In addition, organic compounds such as tetrathiafulvalene (TTF) can be used. You can also use things.

[0138] The above-mentioned light-emitting layer, hole injection layer, hole transport layer, electron transport layer, and electron injection layer are Each can be formed by a method such as a vapor deposition method (including a vacuum vapor deposition method), an inkjet method, a coating method, a gravure printing method, etc. In addition to the materials described above, inorganic compounds such as quantum dots and high molecular compounds (oligomers, dendrimers, polymers, etc.) may be used for the light-emitting layer, hole injection layer, hole transport layer, electron transport layer, and electron injection layer described above.

[0139] As the quantum dots, colloidal quantum dots, alloy-type quantum dots, core-shell type quantum dots, core-type quantum dots, etc. may be used. Further, 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 containing quantum dots may be used. Alternatively, 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 be used.

[0140] ≪Pair of electrodes≫ The electrode 101 and the electrode 102 have functions as an anode or a cathode of the light-emitting element. The electrodes 101 and the electrode 102 can be formed using a metal, an alloy, a conductive compound, and mixtures or laminates thereof.

[0141] One of the electrode 101 or the electrode 102 is preferably formed of a conductive material having a function of reflecting light. Examples of the conductive material include aluminum (Al) or an alloy containing Al. Examples of the alloy containing Al include an alloy containing Al and L (L represents one or more of titanium (Ti), neodymium (Nd), nickel (Ni), and lanthanum (La)). Examples include alloys such as an Al alloy, for example, an alloy containing Al and Ti, or an alloy containing Al, Ni, and La. Aluminum has a low resistance value and a high light reflectance. Also, aluminum is abundant in the earth's crust and is inexpensive, so the manufacturing cost of a light-emitting device using aluminum can be reduced. Further, an alloy containing silver (Ag) or one or more of Ag and N (where N represents yttrium (Y), Nd, magnesium (Mg), ytterbium (Yb), Al, Ti, gallium ( Ga), zinc (Zn), indium (In), tungsten (W), manganese (Mn), tin (Sn), iron (Fe), Ni, copper (Cu), palladium (Pd), iridium (Ir ), or gold (Au)) may be used. Examples of alloys containing silver include an alloy containing silver, palladium, and copper, an alloy containing silver and copper, an alloy containing silver and magnesium, an alloy containing silver and nickel, an alloy containing silver and gold, an alloy

[0142] containing silver and ytterbium, etc. In addition, transition metals such as tungsten, chromium (Cr), molybdenum (Mo ), copper, and titanium can be used. The light emitted from the light-emitting layer is taken out through one or both of the electrodes 101 and 102. Therefore, at least one of the -2 electrodes 101 and 102 is preferably formed of a conductive material having

[0143] a function of transmitting light. Examples of the conductive material It may be formed of a conductive material. As the conductive material, the reflectance of visible light is 20 % or more and 80% or less, preferably 40% or more and 70% or less, and the resistivity thereof is 1×10 -2 Ω·cm or less. For example, it can be formed by using one or more of a conductive metal, alloy, conductive compound, etc. Specifically, for example, indium tin oxide (Indium Tin Oxide, hereinafter ITO), silicon or indium tin oxide containing silicon oxide (abbreviation: ITSO), indium oxide - zinc oxide (Indium Zinc Oxide), indium tin oxide containing titanium, indium - titanium oxide, indium oxide containing tungsten oxide and zinc oxide, etc. can be used. Also, a metal thin film having a degree of light transmission (preferably a thickness of 1 nm or more and 30 nm or less) can be used. As the metal, for example, Ag, or an alloy such as Ag and Al, Ag and Mg, Ag and Au, Ag and Yb, etc. can be used. In addition, in this specification, etc., a material having a function of transmitting light may be any material having a function of transmitting visible light and having conductivity. For example, in addition to the oxide conductors represented by the above ITO, it includes oxide semiconductors or organic conductors containing organic substances. As the organic conductor containing an organic substance, for example, a composite material formed by mixing an organic compound and an electron donor (donor), a composite material formed by mixing an organic compound and an electron acceptor (acceptor), etc. can be mentioned. In addition, an inorganic carbon - based material such as graphene may be used. Also, the resistivity of the material is preferably 1×10 Ω·cm or less, more preferably 1×10 Ω·cm

[0144] In addition, in this specification, etc., a material having a function of transmitting light may be any material having a function of transmitting visible light and having conductivity. For example, in addition to the oxide conductors represented by the above ITO, it includes oxide semiconductors or organic conductors containing organic substances. As the organic conductor containing an organic substance, for example, a composite material formed by mixing an organic compound and an electron donor (donor), a composite material formed by mixing an organic compound and an electron acceptor (acceptor), etc. can be mentioned. In addition, in this specification, etc., a material having a function of transmitting light may be any material having a function of transmitting visible light and having conductivity. For example, in addition to the oxide conductors represented by the above ITO, it includes oxide semiconductors or organic conductors containing organic substances. As the organic conductor containing an organic substance, for example, a composite material formed by mixing an organic compound and an electron donor (donor), a composite material formed by mixing an organic compound and an electron acceptor (acceptor), etc. can be mentioned. In addition to the oxide conductors represented by the above ITO, it includes oxide semiconductors or organic conductors containing organic substances. As the organic conductor containing an organic substance, for example, a composite material formed by mixing an organic compound and an electron donor (donor), a composite material formed by mixing an organic compound and an electron acceptor (acceptor), etc. can be mentioned. As the organic conductor containing an organic substance, for example, a composite material formed by mixing an organic compound and an electron donor (donor), a composite material formed by mixing an organic compound and an electron acceptor (acceptor), etc. can be mentioned. Examples include a composite material formed by mixing an organic compound and an electron donor (donor), a composite material formed by mixing an organic compound and an electron acceptor (acceptor), etc. In addition, an inorganic carbon - based material such as graphene may be used. Also, the resistivity of the material is preferably 1×10 Ω·cm or less, more preferably 1×10 5 Ω·cm or less, and even more preferably 1×10 4 Ω·cm The following.

[0145] Also, by laminating a plurality of the above materials, one or both of the electrodes 101 and 102 may be formed. Or both may be formed.

[0146] Also, in order to improve the light extraction efficiency, in contact with an electrode having a function of transmitting light, a material having a refractive index higher than that of the electrode may be formed. Such a material may be any material having a function of transmitting visible light, and may be a conductive material or a non-conductive material. For example, in addition to the above-described oxide conductors, oxide semiconductors and organic substances may be mentioned. Examples of the organic substance include the materials exemplified for the light emitting layer, hole injection layer, hole transport layer, electron transport layer, or electron injection layer. Also, inorganic carbon-based materials and metals in the form of thin films through which light can pass can be used. Using these materials having a high refractive index, a plurality of layers having a thickness of several nm to several tens of nm may be laminated. electrode, a material having a higher refractive index than the electrode may be formed. Such a material may be any material having a function of transmitting visible light, and may be a conductive material or a non-conductive material. For example, in addition to the above-described oxide conductors, oxide semiconductors and organic substances may be mentioned. Examples of the organic substance include the materials exemplified for the light emitting layer, hole injection layer, hole transport layer, electron transport layer, or electron injection layer. Also, inorganic carbon-based materials and metals in the form of thin films through which light can pass can be used. Using these materials having a high refractive index, a plurality of layers having a thickness of several nm to several tens of nm may be laminated. any material having a function of transmitting visible light, and may be a conductive material or a non-conductive material. For example, in addition to the above-described oxide conductors, oxide semiconductors and organic substances may be mentioned. Examples of the organic substance include the materials exemplified for the light emitting layer, hole injection layer, hole transport layer, electron transport layer, or electron injection layer. Also, inorganic carbon-based materials and metals in the form of thin films through which light can pass can be used. Using these materials having a high refractive index, a plurality of layers having a thickness of several nm to several tens of nm may be laminated. For example, in addition to the above-described oxide conductors, oxide semiconductors and organic substances may be mentioned. Examples of the organic substance include the materials exemplified for the light emitting layer, hole injection layer, hole transport layer, electron transport layer, or electron injection layer. Also, inorganic carbon-based materials and metals in the form of thin films through which light can pass can be used. Using these materials having a high refractive index, a plurality of layers having a thickness of several nm to several tens of nm may be laminated. Examples of the organic substance include the materials exemplified for the light emitting layer, hole injection layer, hole transport layer, electron transport layer, or electron injection layer. Also, inorganic carbon-based materials and metals in the form of thin films through which light can pass can be used. Using these materials having a high refractive index, a plurality of layers having a thickness of several nm to several tens of nm may be laminated. Examples of the organic substance include the materials exemplified for the light emitting layer, hole injection layer, hole transport layer, electron transport layer, or electron injection layer. Also, inorganic carbon-based materials and metals in the form of thin films through which light can pass can be used. Using these materials having a high refractive index, a plurality of layers having a thickness of several nm to several tens of nm may be laminated. Using these materials having a high refractive index, a plurality of layers having a thickness of several nm to several tens of nm may be laminated. Using these materials having a high refractive index, a plurality of layers having a thickness of several nm to several tens of nm may be laminated.

[0147] When the electrode 101 or the electrode 102 functions as a cathode, it preferably has a material having a small work function (3.8 eV or less). For example, elements belonging to Group 1 or Group 2 of the periodic table (alkali metals such as lithium, sodium, and cesium, alkaline earth metals such as calcium and strontium, magnesium, etc.), alloys containing these elements (e.g., Ag and Mg, Al and Li), rare earth metals such as europium (Eu) and Yb, alloys containing these rare earth metals, aluminum, alloys containing silver, etc. can be used. (3.8 eV or less) preferably has a material. For example, elements belonging to Group 1 or Group 2 of the periodic table (alkali metals such as lithium, sodium, and cesium, alkaline earth metals such as calcium and strontium, magnesium, etc.), alloys containing these elements (e.g., Ag and Mg, Al and Li), rare earth metals such as europium (Eu) and Yb, alloys containing these rare earth metals, aluminum, alloys containing silver, etc. can be used. Group 1 or Group 2 of the periodic table (alkali metals such as lithium, sodium, and cesium, alkaline earth metals such as calcium and strontium, magnesium, etc.), alloys containing these elements (e.g., Ag and Mg, Al and Li), rare earth metals such as europium (Eu) and Yb, alloys containing these rare earth metals, aluminum, alloys containing silver, etc. can be used. Group 1 or Group 2 of the periodic table (alkali metals such as lithium, sodium, and cesium, alkaline earth metals such as calcium and strontium, magnesium, etc.), alloys containing these elements (e.g., Ag and Mg, Al and Li), rare earth metals such as europium (Eu) and Yb, alloys containing these rare earth metals, aluminum, alloys containing silver, etc. can be used. Ag and Mg, Al and Li), rare earth metals such as europium (Eu) and Yb, alloys containing these rare earth metals, aluminum, alloys containing silver, etc. can be used. rare earth metals such as europium (Eu) and Yb, alloys containing these rare earth metals, aluminum, alloys containing silver, etc. can be used.

[0148] Also, when the electrode 101 or the electrode 102 is used as an anode, it is preferable to use a material having a large work function (4.0 eV or more). 0 eV or more) it is preferable to use a material.

[0149] Further, the electrodes 101 and 102 may be a laminate of a conductive material having a function of reflecting light and a conductive material having a function of transmitting light. In that case, the electrodes 101 and 1 02 are preferably capable of resonating the desired light from each light-emitting layer and enhancing the light of that wavelength, and thus having a function of adjusting the optical distance.

[0150] The film-forming methods of the electrodes 101 and 102 may 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.

[0151] <<Substrate>> Further, 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 the order of manufacturing on the substrate, it may be laminated in order from the electrode 101 side, or may be laminated in order from the electrode 102 side.

[0152] In addition, 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 is a substrate that can be bent (flexible), and examples thereof include plastic substrates made of polycarbonate , polyarylate, etc. In addition, a film, an inorganic vapor deposition film, or the like can also be used. 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.

[0153] For example, in the present invention, a light emitting element can be formed using various substrates. The type of the substrate is not particularly limited. An example of the substrate is a semiconductor substrate (e.g., a single crystal substrate or silicon substrate), SOI substrate, glass substrate, quartz substrate, plastic substrate, metal Substrate, stainless steel substrate, substrate with stainless steel foil, tungsten substrate, substrate with tungsten foil, flexible substrate, laminated film, fibrous Examples of glass substrates include barium phosphide-based paper or base films. Examples include borosilicate glass, aluminoborosilicate glass, and soda-lime glass. Examples of the functional substrate, laminate film, base film, etc. are as follows. For example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), Representative examples include polyethersulfone (PES) and polytetrafluoroethylene (PTFE). For example, plastics such as acrylic resins are used. Examples include polypropylene, polyester, polyvinyl fluoride, or polyvinyl chloride. Examples include polyamide, polyimide, aramid, epoxy, and inorganic. Examples include machine-deposited films and papers.

[0154] In addition, a flexible substrate may be used as the substrate, and the light emitting element may be formed directly on the flexible substrate. Alternatively, a release layer may be provided between the substrate and the light-emitting element. After a part or all of a chip is completed, it is separated from the board and used to transfer it to another board. In this case, the light-emitting element can be transferred onto a substrate having poor heat resistance or a flexible substrate. Oh, for the above-described 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 a substrate can be used.

[0155] That is, a light-emitting element may be formed using a certain substrate, and then the light-emitting element may be transferred to another substrate, and the light-emitting element may be disposed on another substrate. As an example of the substrate to which the light-emitting element is transferred, in addition to the substrate described above, a cellophane substrate, a stone substrate, a wood substrate, a cloth substrate (including natural fibers (silk, cotton, hemp), synthetic fibers (nylon, polyurethane, polyester), or recycled fibers (acetate, cupra, rayon, recycled polyester), etc.), a leather substrate, or a rubber substrate is available. By using these substrates, a light-emitting element that is difficult to break, a light-emitting element with high heat resistance, a light-emitting element with reduced weight, or a light-emitting element with reduced thickness can be obtained.

[0156] Further, for example, a field effect transistor (FET) may be formed on the above-described substrate, and the light-emitting element 152 may be fabricated on an electrode electrically connected to the FET. Thereby, an active matrix type display device for controlling the driving of the light-emitting element 152 by the FET can be fabricated.

[0157] Note that in this embodiment, one aspect of the present invention has been described. Or, in other embodiments, one aspect of the present invention may be described. However, one aspect of the present invention is not limited to these. That is, in this embodiment and other embodiments, various aspects of the invention are described, so one aspect of the present invention is not limited to a specific aspect. For example, as one aspect of the present invention, an example when applied to a light-emitting element has been shown, but one aspect of the present invention is not limited thereto. ​​​​Yes. For example, in some cases or depending on the situation, one aspect of the present invention may not be applicable to the light-emitting element. Or, for example, in one aspect of the present invention, a first organic compound, a second organic compound, and a guest material having a function of converting triplet excitation energy into light emission are provided. The LUMO level of the first organic compound is lower than the LUMO level of the second organic compound, and the HOMO level of the first organic compound is lower than the HOMO level of the second organic compound. Examples of such cases have been shown, but one aspect of the present invention is not limited thereto. In some cases or depending on the situation, in one aspect of the present invention, for example, the LUMO level of the first organic compound may not be lower than the LUMO level of the second organic compound. Alternatively, the HOMO level of the first organic compound may not be lower than the HOMO level of the second organic compound. Or, for example, in one aspect of the present invention, examples of cases where the first organic compound and the second organic compound form an exciplex have been shown, but one aspect of the present invention is not limited thereto. In some cases or depending on the situation, in one aspect of the present invention, for example, the first organic compound and the second organic compound may not form an exciplex. Or, for example, in one aspect of the present invention, examples of cases where the LUMO level of the guest material is lower than the LUMO level of the first organic compound and the HOMO level of the guest material is lower than the HOMO level of the second organic compound have been shown, but one aspect of the present invention is not limited thereto. In some cases or depending on the situation, in one aspect of the present invention, for example, the LUMO level of the guest material may not be lower than the LUMO level of the first organic compound. Alternatively, the HOMO level of the guest material may not be lower than the HOMO level of the second organic compound.

[0158] ​​​​​​​​​​​As described above, the configuration shown in the present embodiment can be used in appropriate combination with other embodiments. It can be used.

[0159] (Embodiment 2) In the present 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 FIGS. 3 and 4. In FIGS. 3 and 4, portions having the same functions as those indicated by the reference numerals shown in FIG. 1(A) are shown with the same hatch pattern, and the reference numerals may be omitted. Also, portions having the same functions may be given the same reference numerals, and detailed descriptions thereof may be omitted. For the light-emitting element having a configuration different from that of the light-emitting element shown in Embodiment 1, the following description will be given with reference to FIGS. 3 and 4. In FIGS. 3 and 4, portions having the same functions as those indicated by the reference numerals shown in FIG. 1(A) are shown with the same hatch pattern, and the reference numerals may be omitted. Also, portions having the same functions may be given the same reference numerals, and detailed descriptions thereof may be omitted. (A) are shown with the same hatch pattern, and the reference numerals may be omitted. Also, portions having the same functions may be given the same reference numerals, and detailed descriptions thereof may be omitted. Portions having the same functions are given the same reference numerals, and detailed descriptions thereof may be omitted. The description thereof may be omitted.

[0160] <Example configuration 1 of the light-emitting element> FIG. 3(A) is a schematic cross-sectional view of the light-emitting element 250.

[0161] The light-emitting element 250 shown in FIG. 3(A) has a plurality of light-emitting units (light-emitting unit 106 and light-emitting unit 1 08) between a pair of electrodes (electrode 101 and electrode 102). 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. That is, the light-emitting element 152 shown in FIG. 1 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 the following description will be given assuming that the electrode 101 functions as an anode and the electrode 102 functions as a cathode, the configuration of the light-emitting element 250 may be reversed. 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 the following description will be given assuming that the electrode 101 functions as an anode and the electrode 102 functions as a cathode, the configuration of the light-emitting element 250 may be reversed. 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 the following description will be given assuming that the electrode 101 functions as an anode and the electrode 102 functions as a cathode, the configuration of the light-emitting element 250 may be reversed. It doesn't matter. However, the following description will be given assuming that the electrode 101 functions as an anode and the electrode 102 functions as a cathode. However, the configuration of the light-emitting element 250 may be reversed. It doesn't matter.

[0162] Also, in the light-emitting element 250 shown in FIG. 3(A), the light-emitting unit 106 and the light-emitting unit 108 are laminated, and a charge generation layer is provided between the light-emitting unit 106 and the light-emitting unit 108. The production layer 115 is provided. Note that the light-emitting unit 106 and the light-emitting unit 108 may have the same configuration or different configurations. For example, it is preferable to use the EL layer 100 shown in FIG. 1 for the light-emitting unit 108.

[0163] In addition, the light-emitting element 250 includes a light-emitting layer 120 and a light-emitting layer 170. The light-emitting unit 106 further includes a hole injection layer 111, a hole transport layer 112, an electron transport layer 113, and an electron injection layer 114 in addition to the light-emitting layer 120. The light-emitting unit 108 includes a hole injection layer 116, a hole transport layer 117, an electron transport layer 118, and an electron injection layer 11 9 in addition to the light-emitting layer 170.

[0164] 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. Alternatively, both of these configurations may be laminated.

[0165] 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 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, macromolecular compounds (oligomers, dendrimers, polymers, etc.) can be used. Note that as the organic compound, the hole mobility is 1×10 cm -6 2 / Vs or more. However, any material other than these may be used as long as it has higher hole-transporting properties than electrons. The composite material of the organic compound and the acceptor substance is for carrier injection ​​​​Since it is excellent in charge generation property and carrier transport property, low-voltage driving and low-current driving can be realized. . When the surface on the anode side of the light-emitting unit is in contact with the charge generation layer 115 as in the light-emitting unit 108, the charge generation layer 115 can also serve as the hole injection layer or the hole transport layer of the light-emitting unit. Therefore, the light-emitting unit may be configured without a hole injection layer or a hole transport layer.

[0166] 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 material and other layers formed of materials. For example, it may be formed by combining a layer containing a composite material of an organic compound and an acceptor material and a layer containing one of the compounds selected from electron-donating materials and a compound having high electron transport property. Further, it may be formed by combining a layer containing a composite material of an organic compound and an acceptor material and a layer containing a transparent conductive film.

[0167] 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. 3(A), when a voltage is applied such that the potential of the electrode 101 is higher than the potential of the electrode 102, the charge generation layer 115 injects electrons into the light-emitting unit 106 and injects holes into the light-emitting unit 108.

[0168] Note that the charge generation layer 115 preferably has light transmittance 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 has a lower conductivity than the pair of electrodes (electrode 101 and electrode 102). It can still function.

[0169] 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 layer is laminated can be suppressed.

[0170] Also, in FIG. 3(A), the light emitting device having two light emitting units was described. However, it can be similarly applied to a light emitting device in which three or more light emitting units are laminated. As shown in the light emitting device 250, by arranging a plurality of light emitting units between a pair of electrodes separated by a charge generation layer, high-brightness light emission can be enabled while keeping the current density low, and furthermore, a long-life light emitting device can be realized. Also, a light emitting device with low power consumption can be realized.

[0171] Note that by applying the configuration shown in Embodiment 1 to at least one of the plurality of units, a light emitting device with high luminous efficiency can be provided.

[0172] Also, the light emitting layer 170 included in the light emitting unit 108 preferably has the same configuration as the light emitting layer 140 shown in Embodiment 1. By having the same configuration as the light emitting layer 140 shown in Embodiment 1, the light emitting device 250 has a phosphorescent material as a light emitting material and is preferably a light emitting device with high luminous efficiency.

[0173] Also, as shown in FIG. 3(B), the light emitting layer 120 included in the light emitting unit 106 has a host material 121 and a guest material 122. Note that the guest material 122 is a fluorescent material and will be described below. ​​​​​​​​​

[0174] ≪Light-emitting mechanism of light-emitting layer 120≫ The light-emitting mechanism of light-emitting layer 120 will be described below.

[0175] Electrons and holes injected from a pair of electrodes (electrode 101 and electrode 102) or a charge generation layer recombine in the light-emitting layer 120, generating excitons. Since the host material 121 is present in a large amount compared to the guest material 122, the generation of excitons forms an excited state of the host material 121. Note that an exciton is a pair of carriers (electrons and holes). Since an exciton has energy, the material in which the exciton is generated becomes an excited state. When the formed excited state of the host material 121 is a singlet excited state, singlet excitation energy transfers from the S1 level of the host material 121 to the S1 level of the guest material 122, forming a singlet excited state of the guest material 122. Since the guest material 122 is a fluorescent material, when a singlet excited state is formed in the guest material 122, the guest material 122 emits light promptly. In this case, in order to obtain high luminous efficiency, it is preferable that the fluorescence quantum yield of the guest material 122 is high. Note that the same applies when carriers recombine in the guest material 122 and the generated excited state is a singlet excited state.

[0176] Note that an exciton is a pair of carriers (electrons and holes). Since an exciton has energy, the material in which the exciton is generated becomes an excited state. Since an exciton has energy, the material in which the exciton is generated becomes an excited state.

[0177] When the formed excited state of the host material 121 is a singlet excited state, singlet excitation energy transfers from the S1 level of the host material 121 to the S1 level of the guest material 122, forming a singlet excited state of the guest material 122. Since the guest material 122 is a fluorescent material, when a singlet excited state is formed in the guest material 122, the guest material 122 emits light promptly. In this case, in order to obtain high luminous efficiency, it is preferable that the fluorescence quantum yield of the guest material 122 is high. Note that the same applies when carriers recombine in the guest material 122 and the generated excited state is a singlet excited state. Since the guest material 122 is a fluorescent material, when a singlet excited state is formed in the guest material 122, the guest material 122 emits light promptly. In this case, in order to obtain high luminous efficiency, it is preferable that the fluorescence quantum yield of the guest material 122 is high. Note that the same applies when carriers recombine in the guest material 122 and the generated excited state is a singlet excited state.

[0178] Since the guest material 122 is a fluorescent material, when a singlet excited state is formed in the guest material 122, the guest material 122 emits light promptly. In this case, in order to obtain high luminous efficiency, it is preferable that the fluorescence quantum yield of the guest material 122 is high. Note that the same applies when carriers recombine in the guest material 122 and the generated excited state is a singlet excited state. Since the guest material 122 is a fluorescent material, when a singlet excited state is formed in the guest material 122, the guest material 122 emits light promptly. In this case, in order to obtain high luminous efficiency, it is preferable that the fluorescence quantum yield of the guest material 122 is high. Note that the same applies when carriers recombine in the guest material 122 and the generated excited state is a singlet excited state. Since the guest material 122 is a fluorescent material, when a singlet excited state is formed in the guest material 122, the guest material 122 emits light promptly. In this case, in order to obtain high luminous efficiency, it is preferable that the fluorescence quantum yield of the guest material 122 is high. Note that the same applies when carriers recombine in the guest material 122 and the generated excited state is a singlet excited state. Since the guest material 122 is a fluorescent material, when a singlet excited state is formed in the guest material 122, the guest material 122 emits light promptly. In this case, in order to obtain high luminous efficiency, it is preferable that the fluorescence quantum yield of the guest material 122 is high. Note that the same applies when carriers recombine in the guest material 122 and the generated excited state is a singlet excited state. Since the guest material 122 is a fluorescent material, when a singlet excited state is formed in the guest material 122, the guest material 122 emits light promptly. In this case, in order to obtain high luminous efficiency, it is preferable that the fluorescence quantum yield of the guest material 122 is high. Note that the same applies when carriers recombine in the guest material 122 and the generated excited state is a singlet excited state.

[0179] Next, the case where a triplet excited state of the host material 121 is formed by carrier recombination will be described. The energy levels of the host material 121 and the guest material 122 in this case are as follows. The energy levels of the host material 121 and the guest material 122 in this case are as follows. The correlation of the levels is shown in Fig. 3(C). The notations and symbols in Fig. 3(C) are as follows That is. Since it is preferable that the T1 level of the host material 121 is lower than the T1 level of the guest material 122 in Fig. 3(C), this case is illustrated, but the T1 level of the host material 121 may be higher than the T1 level of the guest material 122

[0180] ·Host(121): Host material 121 ·Guest(122): Guest material 122 (fluorescent material) ·S FH : S1 level of host material 121 ·T FH : T1 level of host material 121 ·S FG : S1 level of guest material 122 (fluorescent material) ·T FG : T1 level of guest material 122 (fluorescent material)

[0181] As shown in Fig. 3(C), by triplet - triplet annihilation (TTA), triplets generated by the recombination of carriers interact with each other, and transfer excitation energy and exchange spin angular momentum with each other. As a result, a reaction occurs in which singlet excitons having the energy of the S1 level (S ) of the host material 121 are converted (see TTA in Fig. 3(C)). The singlet excitation energy of the host material 121 FH is transferred from S to the S1 level (S ) of the guest material 122, which has lower energy than that (see route E1 in Fig. 3(C)). An energy transfer occurs FH to the S1 level (S ) of the guest material 122, forming a singlet excited state of the guest material 122, and the guest material 122 emits light FG ) (see route E1 in Fig. 3(C)), forming a singlet excited state of the guest material 122, and the guest material 122 emits light

[0182] ​In addition, when the density of triplet excitons in the light-emitting layer 120 is sufficiently high (for example, 1×10 -12 cm -3 or more), the deactivation of singlet triplet excitons can be ignored, and only the reaction by two adjacent triplet excitons can be considered.

[0183] When carriers recombine in the guest material 122 to form a triplet excited state, since the energy of the triplet excited state of the guest material 122 is thermally deactivated, it becomes difficult to utilize it for light emission. However, when the T1 level (T ) of the host material 121 is lower than the T1 level (T FH ) of the guest material 1 22, the triplet excitation energy of the guest material 122 can FG transfer its energy from the T1 level (T ) of the guest material 122 to the T1 level (T FG ) of the host material 121 (see Route E2 in Fig. 3(C)), and then it can be utilized for TTA. FH That is, it is preferable that the host material 121 has a function of converting triplet excitation energy into singlet excitation energy by TTA. By doing so, a part of the triplet excitation energy generated in the light-emitting layer 120 can be converted into singlet excitation energy by TTA in the host material 121, and the singlet excitation energy can be transferred to the guest material 122, so that fluorescence emission can be extracted. For this purpose, it is preferable that the S1 level (S

[0184] ) of the host material 121 is higher than the S1 level (S ) of the guest material 122. Also, the T1 level (T ) of the host material 121 is lower than the T1 level (T ) of the guest material 122. FH ) of the host material 121 is preferably higher than the S1 level (S FG ) of the guest material 122. Also, the T1 level (T ) of the host material 121 is lower than the T1 level (T FH ) of the guest material 122. FG ​​​​ is preferable.

[0185] In particular, when the T1 level (T FG ) of the guest material 122 is lower than the T1 level (T FH ) of the host material 121, the weight ratio of the host material 121 to the guest material 122 is preferably lower for the guest material 122. Specifically, the weight ratio of the guest material 122 to 1 of the host material 121 is preferably greater than 0 and 0.05 or less. By setting such a weight ratio relationship, the probability of carriers recombining with the guest material 122 can be reduced. Further, the probability of energy transfer from the T1 level (T ) of the host material 121 to the T1 level (T ) of the guest material 122 can be reduced. FH ) to the T1 level (T FG ) of the guest material 122 can be reduced.

[0186] Note that the host material 121 may be composed of a single compound or a plurality of compounds.

[0187] Note that in each of the above configurations, the emission colors exhibited by the guest materials used in the light emitting units 106 and 108 may be the same or different. When the guest material has a function of emitting light of the same color in the light emitting unit 106 and the light emitting unit 108, the light emitting element 250 preferably becomes a light emitting element that exhibits high emission luminance at a low current value. Further, when the guest material has a function of emitting light of different colors in the light emitting unit 106 and the light emitting unit 108, the light emitting element 250 preferably becomes a light emitting element that exhibits multi-color emission. In this case, it is preferable that either one or both of the light emitting layers 120 and 170 have a light emission wavelength ​​​​​By using a plurality of different light-emitting materials, the emission spectrum exhibited by the light-emitting element 250 is light in which emissions having different emission peaks are synthesized, resulting in an emission spectrum having at least two maxima.

[0188] The above configuration is also suitable for obtaining white light emission. By setting the lights of the light-emitting layer 120 and the light-emitting layer 170 to be complementary colors to each other, white light emission can be obtained. In particular, it is preferable to select guest materials so as to obtain white light emission with high color rendering properties, or light emission having at least red, green, and blue.

[0189] Alternatively, one or both of the light-emitting layer 120 and 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, one or both of the light-emitting layer 120 and the light-emitting layer 170 may be configured by a plurality 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 a light-emitting layer, a substance having hole transport properties is used as the host material of the first light-emitting layer, and a substance having electron transport properties is used as the host material of the second light-emitting layer. 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. A configuration having a plurality of light-emitting materials having functions of emitting lights of different colors from each other can also obtain white light emission with high color rendering properties composed of the three primary colors or four or more emission colors.

[0190] Further, the light-emitting unit 106 and the light-emitting unit 108 have guest materials having different emission colors.​​​​​​​​​​​ In this case, it is preferable that the light emission from the light-emitting layer 120 has a peak of light emission on the shorter wavelength side than the light emission from the light-emitting layer 170. A light-emitting device using a material having a high triplet excitation energy level tends to have rapid luminance degradation. Therefore, by using TTA in the light-emitting layer that exhibits short-wavelength light emission, a light-emitting device with little luminance degradation can be provided. - Example Configuration 2 of the Light-Emitting Device Next, a configuration example different from the light-emitting device shown in FIG. 3 will be described below with reference to FIGS. 4(A), (B), and (C). -

[0191] <Example Configuration of the Light-Emitting Device 2> Next, a configuration example different from the light-emitting device shown in FIG. 3 will be described below using FIGS. 4(A), (B), and (C). -

[0192] FIG. 4(A) is a schematic cross-sectional view of the light-emitting device 252.

[0193] The light-emitting device 252 shown in FIG. 4(A) has a structure in which an EL layer 110 is sandwiched between a pair of electrodes (electrode 101 and electrode 102). In the light-emitting device 252, although it will be described below assuming that electrode 101 functions as the anode and electrode 102 functions as the cathode, the configuration of the light-emitting device 252 may be reversed. - - - The configuration of the light-emitting device 252 may be reversed.

[0194] Further, the EL layer 110 has a light-emitting layer 180, and the light-emitting layer 180 has the light-emitting layer 120 and the light-emitting layer 170. In the light-emitting device 252, in addition to the light-emitting layer, a hole injection layer 111, a hole transport layer 112, an electron transport layer 118, and an electron injection layer 119 are shown as the EL layer 110, but these laminated structures are merely examples, and the configuration of the EL layer 110 in the light-emitting device 252 is not limited to these. For example, in the EL layer 110, the lamination order of the above layers may be changed. Or, in the EL layer 110, functional layers other than the above layers may be provided. - - - - The configuration of the EL layer 110 in the light-emitting device 252 is not limited to these. - For example, in the EL layer 110, the lamination order of the above layers may be changed. As the functional layer, for example, it may have a configuration having a function of reducing a hole or electron injection barrier, a function of improving hole or electron transportability, a function of inhibiting hole or electron transportability, or a function of generating holes or electrons. In addition, as shown in FIG. 4(B), the light-emitting layer 120 includes a host material 121 and a guest material 122. The light-emitting layer 170 also includes a host material 171 and a guest material 172.

[0195] The host material 171 includes an organic compound 171_1 and an organic compound 171_2. Hereinafter, it is assumed that the guest material 122 is a fluorescent material and the guest material 172 is a phosphorescent material.

[0196] ≪Light-emitting mechanism of the light-emitting layer 180≫ The light-emitting mechanism of the light-emitting layer 120 is the same as the light-emitting mechanism of the light-emitting layer 120 shown in FIG. 3. In addition, the light-emitting mechanism of the light-emitting layer 170 is the same as the light-emitting mechanism of the light-emitting layer 140 shown in Embodiment 1. That is, the host material 171, the organic compound 171_1, the organic compound 171_2, and the guest material 172 have the same configurations as the host material 141, the guest material 142, the organic compound 141_1, and the organic compound 141_2, respectively.

[0197]

[0198] When the light-emitting layer 120 and the light-emitting layer 170 are in contact with each other as shown in the light-emitting element 252, at the interface between the light-emitting layer 120 and the light-emitting layer 170, even if energy transfer (particularly energy transfer of the triplet excited state) from the exciplex to the host material 121 of the light-emitting layer 120 occurs, the triplet excitation energy can be converted into light in the light-emitting layer 120.

[0198] ​​​In addition, it is preferable that the T1 level of the host material 121 in the light-emitting layer 120 is lower than the T1 levels of the organic compounds 171_1 and 171_2 included in the light-emitting layer 170. Further, in the light-emitting layer 120, it is preferable that the S1 level of the host material 121 is higher than the S1 level of the guest material 122 (fluorescent material), and that the T1 level of the host material 121 is lower than the T1 level of the guest material 122 (fluorescent material). Specifically, FIG. 4(C) shows the correlation of energy levels in the case where TTA is used for the light-emitting layer 120 and ExTET is used for the light-emitting layer 170. Note that the notations and symbols in FIG. 4(C) are as follows. · Fluorescence EML(120): Light-emitting layer 120 (fluorescent light-emitting layer) · Phosphorescence EML(170): Light-emitting layer 170 (phosphorescent light-emitting layer) · Host(121): Host material 121

[0199] · Guest(122): Guest material 122 (fluorescent material) · Host(171_1): Host material (organic compound 171_1) · Guest(172): Guest material 172 (phosphorescent material) · Exciplex: Excimer (organic compounds 171_1 and 171_2) · S FH : S1 level of host material 121 · T FH : T1 level of host material 121 · S FG : S1 level of guest material 122 (fluorescent material) · T FG : T1 level of guest material 122 (fluorescent material) · S PH : S1 level of host material (organic compound 171_1) · T PH : T1 level of host material (organic compound 171_1) · S PG : S1 level of host material (organic compound 171_1) · T PH : T1 level of host material (organic compound 171_1) · T PG:T1 level of guest material 172 (phosphorescent material) ·S E : S1 level of the exciplex T E :T1 level of the exciplex

[0200] As shown in Figure 4(C), since exciplexes exist only in excited states, Exciton diffusion between the complexes is difficult. Also, the excited energy level of the exciplex (S E , T E ) is the excitation light of the organic compound 171_1 (i.e., the host material of the phosphorescent material) in the light-emitting layer 170. Energy level (S PH , T PH ) is lower than that of the organic compound 171_ In other words, in the phosphorescent light-emitting layer (light-emitting layer 170), the energy is not diffused to the Since the exciton diffusion distance of the exciplex is short, the efficiency of the phosphorescent light-emitting layer (light-emitting layer 170) can be maintained. In addition, the interface between the fluorescent light-emitting layer (light-emitting layer 120) and the phosphorescent light-emitting layer (light-emitting layer 170) In the phosphorescent light-emitting layer (light-emitting layer 170), a part of the triplet excitation energy of the exciplex is converted into a fluorescent Even if the phosphorus diffuses into the light-emitting layer (light-emitting layer 120), the phosphorus diffuses into the fluorescent layer (light-emitting layer 120). The triplet excitation energy of the photoluminescence layer 120 is converted into light emission through TTA. It is possible to reduce energy loss.

[0201] As described above, the light emitting device 252 uses ExTET for the light emitting layer 170 and By using TTA in 20, energy loss is reduced, resulting in high luminous efficiency. As shown in the light-emitting element 252, the light-emitting layer 120 and the light-emitting layer In the case where the heat exchanger 170 and the heat exchanger 170 are in contact with each other, the energy loss is reduced and the E The number of L layers 110 can be reduced. Therefore, the light-emitting device can be manufactured at low cost. It can be said that:

[0202] The light-emitting layer 120 and the light-emitting layer 170 may not be in contact with each other. In this case, the organic compound 171_1, the organic compound 171_2, or The guest material 172 (phosphorescent material) is excited into the host material 121 in the light-emitting layer 120, Energy transfer via the Dexter mechanism to the guest material 122 (fluorescent material) (especially triplet Therefore, the energy transfer between the light-emitting layer 120 and the light-emitting layer 170 can be prevented. The layer between the layers may have a thickness of about several nm. Specifically, the thickness is 1 nm to 5 nm. This is advantageous because it is possible to suppress an increase in the driving voltage.

[0203] The layer provided between the light-emitting layer 120 and the light-emitting layer 170 may be made of a single material. Alternatively, both a hole transporting material and an electron transporting material may be included. In this case, a bipolar material may be used. The mobility ratio of the hole transport material to the electron transport material is 100 or less. Alternatively, at least one of them may be a host material for the light-emitting layer 170. Even if it is formed from the same material as the substrate material (organic compound 171_1 or organic compound 171_2), This makes it easier to fabricate the light-emitting device and reduces the driving voltage. The hole transporting material and the electron transporting material may form an exciplex, which can generate excitons. Specifically, the host material (organic compound) of the light-emitting layer 170 can be effectively prevented from diffusing. Excitation of organic compounds 171_1 or organic compounds 171_2) or guest materials 172 (phosphorescent materials) From the starting state, it is possible to prevent energy transfer to the host material 121 or the guest material 122 (fluorescent material) of the light-emitting layer 120.

[0204] Also, in the light-emitting element 252, although the light-emitting layer 120 has been described as being on the hole transport layer 112 side and the light-emitting layer 170 is on the electron transport layer 118 side, the light-emitting element of one aspect of the present invention is not limited to this, and the light-emitting layer 120 may be on the electron transport layer 118 side and the light-emitting layer 170 may be on the hole transport layer 112 side.

[0205] Note that in the light-emitting element 252, the carrier recombination region is preferably formed with a certain degree of distribution. For this reason, in the light-emitting layer 120 or the light-emitting layer 170, it is preferable to have appropriate carrier trapping properties. In particular, it is preferable that the guest material 172 (phosphorescent material) of the light-emitting layer 170 has electron trapping properties. Therefore, the configuration of the light-emitting layer 140 shown in Embodiment 1 is suitable as the light-emitting layer 170.

[0206] Note that it is preferable to have a configuration in which the light emission from the light-emitting layer 120 has a light emission peak on the shorter wavelength side than the light emission from the light-emitting layer 170. A light-emitting element using a phosphorescent material that exhibits short-wavelength light emission tends to have rapid luminance degradation. Therefore, by making the short-wavelength light emission fluorescence emission, it is possible to provide a light-emitting element with small luminance degradation.

[0207] Also, by obtaining light of different emission wavelengths from the light-emitting layer 120 and the light-emitting layer 170, it is possible to form a multi-color light-emitting element. In this case, since the emission spectrum is light in which emissions having different emission peaks are synthesized, the emission spectrum has at least two maxima.

[0208] Also, the above configuration is also suitable for obtaining white light emission. By making the light between the light emitting layer 120 and the light emitting layer 170 be in a complementary color relationship with each other, white light emission can be obtained.

[0209] Also, by using a plurality of light emitting materials having different emission wavelengths in either one or both of the light emitting layer 120 and the light emitting layer 170, high color rendering white light emission composed of three primary colors or four or more emission colors can also be obtained. In this case, the light emitting layer may be further divided into layers, and different light emitting materials may be contained in each of the divided layers.

[0210] <Examples of materials that can be used in the light emitting layer> Next, the materials that can be used in the light emitting layer 120 and the light emitting layer 170 will be described below .

[0211] ≪Materials that can be used in the light emitting layer 120≫ In the light emitting layer 120, the host material 121 is present in the largest amount by weight, and the guest material 122 (fluorescent material) is dispersed in the host material 121. The S1 level of the host material 121 is higher than the S1 level of the guest material 122 (fluorescent material), and the T1 level of the host material 121 is preferably lower than the T1 level of the guest material 122 (fluorescent material).

[0212] In the light emitting layer 120, the guest material 122 is not particularly limited, but anthracene derivatives, tetracene derivatives, chrysene derivatives, phenanthrene derivatives, pyrene derivatives, perylene derivatives, stilbene derivatives, acridone derivatives, coumarin derivatives, phenoxazine derivatives, phenothiazine derivatives, etc. are preferred, and for example, the following materials can be used .

[0213] ​ Specifically, 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2 ,2'-bipyridine (abbreviation: PAP2BPy), 5,6-bis[4'-(10-phenyl -9-anthryl)biphenyl-4-yl]-2,2'-bipyridine (abbreviation: PAPP2 BPy), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoro ren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn) , N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H -fluorene-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMem FLPAPrn), N,N'-bis[4-(9-phenyl-9H-fluorene-9-yl )phenyl]-N,N'-bis(4-tert-butylphenyl)-pyrene-1,6-di amine (abbreviation: 1,6tBu-FLPAPrn), N,N'-diphenyl-N,N'-bi s[4-(9-phenyl-9H-fluorene-9-yl)phenyl]-3,8-dicyclo hexylpyrene-1,6-diamine (abbreviation: ch-1,6FLPAPrn), N,N'- bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenylstilb ene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-carbazol-9-yl )-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA ), 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl-2-anth ryl)triphenylamine (abbreviation: 2YGAPPA), N,9-diphenyl-N-[4 -(10-phenyl-9-anthryl)phenyl]-9H-carbazole-3-amine ( Abbreviation: PCAPA), perylene, 2,5,8,11-tetra(tert-butyl)perylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)-4'-(9-phenyl -9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), N,N ''-(2-tert-butylanthracene-9,10-diyl-di-4,1-phenylene )bis[N,N',N'-triphenyl-1,4-phenylenediamine] (abbreviation: DPA BPA), N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl) phenyl]-9H-carbazole-3-amine (abbreviation: 2PCAPPA), N-[4-( 9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl- 1,4-phenylenediamine (abbreviation: 2DPAPPA), N,N,N',N',N'', N'',N''',N'''-octaphenyldibenzo[g,p]chrysene-2,7,1 0,15-tetraamine (abbreviation: DBC1), coumarin 30, N-(9,10-diphenyl -2-anthryl)-N,9-diphenyl-9H-carbazole-3-amine (abbreviation: 2PCAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anth tryl]-N,9-diphenyl-9H-carbazole-3-amine (abbreviation: 2PCABP hA), N-(9,10-diphenyl-2-anthryl)-N,N',N'-triphenyl -1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-bis(1, 1'-biphenyl-2-yl)-2-anthryl]-N,N',N'-triphenyl-1 ,4-phenylenediamine (abbreviation: 2DPABPhA), 9,10-bis(1,1'-b iphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N- Phenylanthracen-2-amine (abbreviation: 2YGABPhA), N,N,9-triphenyl anthracen-9-amine (abbreviation: DPhAPhA), Coumarin 6, Coumarin 545 T, N,N'-diphenylquinacridone (abbreviation: DPQd), Rubrene, 2,8-di-t ert-butyl-5,11-bis(4-tert-butylphenyl)-6,12-diphenyl tetracene (abbreviation: TBRb), Nile Red, 5,12-bis(1,1'-biphenyl -4-yl)-6,11-diphenyltetracene (abbreviation: BPT), 2-(2-{2 -[4-(dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyran-4-yl lidene)propanedinitrile (abbreviation: DCM1), 2-{2-methyl-6-[2-(2, 3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl lidene]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM2), N,N, N',N'-tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation : p-mPhTD), 7,14-diphenyl-N,N,N',N'-tetrakis(4-methyl phenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviation: p-mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl -2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl lidene]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTI ), 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3 ,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl -4H-Pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB), 2-(2 ,6-bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4- ylidene)propanedinitrile (abbreviation: BisDCM), 2-{2,6-bis[2-(8 -methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5 H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene} propanedinitrile (abbreviation: BisDCJTM), 5,10,15,20-tetraphenyl rubisbenzo[5,6]indeno[1,2,3-cd:1’,2’,3’-lm]perylene and the like.

[0214] In addition, in the light-emitting layer 120, materials that can be used for the host material 121 include, although not particularly limited, 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), bis[2-(2-benzoxazolyl)phenolato]zinc(II)( abbreviation: ZnPBO), bis[2-(2-benzothiazolyl)phenolato]zinc(II)( abbreviation: ZnBTZ) and other metal complexes, 2-(4-biphenylyl)-5-(4-tert- butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5 -(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene Zen (abbreviation: OXD-7), 3-(4-biphenylyl)-4-phenyl-5-(4-te rt-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 2,2’,2’ ’-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazo le) (abbreviation: TPBI), bathophenanthroline (abbreviation: BPhen), bathocupro ine (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 also α-NPD), N,N’-bis(3-methylphenyl)-N,N’-diphenyl-[1 ,1’-biphenyl]-4,4’-diamine (abbreviation: TPD), 4,4’-bis[N-( spiro-9,9’-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation : BSPB) and other aromatic amine compounds. Also, anthracene derivatives, phen anthrene derivatives, pyrene derivatives, chrysene derivatives, dibenzo[g,p]chrysene derivatives and other condensed polycyclic aromatic compounds, specifically, 9,10-diphenylanthracene (abbreviation: DPAnth), N,N-diphenyl-9-[4-(10-phenyl-9-anth ryl)phenyl]-9H-carbazole-3-amine (abbreviation: CzA1PA), 4-( 10-phenyl-9-anthryl)triphenylamine (abbreviation: DPhPA), 4-(9 H-carbazol-9-yl)-4’-(10-phenyl-9-anthryl)triphenyl lamine (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]furan N,9-diphenyl}-9H-carbazol-3-amine (abbreviation: PCAPBA), N-(9,10-diphenyl-2-anthryl)-9H-carbazol-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-(1 0-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'-(styryl Ben-3,3'-diyl)diphenanthrene (abbreviation: DPNS), 9,9'-(stilbe 3,3',3''-(phenyl-4,4'-diyl)diphenanthrene (abbreviation: DPNS2), Benzene-1,3,5-triyl)tripylene (abbreviation: TPB3) In addition, among these and known substances, the energy gap of the guest material 122 can be By selecting and using one or more materials with an energy gap larger than that of the good.

[0215] The light-emitting layer 120 may be composed of two or more layers. When the first light-emitting layer and the second light-emitting layer are laminated in order from the hole transport layer side to form the light-emitting layer 120, for the first a substance having hole transport properties is used as the host material of the light-emitting layer, and the host material of the second light-emitting layer There is a configuration in which a substance having electron transport properties is used.

[0216] Also, in the light-emitting layer 120, the host material 121 may be composed of one kind of compound or may be composed of a plurality of compounds. Alternatively, in the light-emitting layer 120, the ho It may have materials other than the st material 121 and the guest material 122.

[0217] ≪Materials that can be used for the light-emitting layer 170≫ As materials that can be used for the light-emitting layer 170, the light-emitting layer 14 shown in the previous Embodiment 1 The materials that can be used for 0 may be adopted. By adopting the materials that can be used for the light-emitting layer 140 for the light-emitting layer 170, a light-emitting device with high luminous efficiency can be manufactured.

[0218] Also, there is no limitation on the emission color of the light-emitting materials included in the light-emitting layer 120 and the light-emitting layer 170, and they may be the same or different from each other. Since the light emitted from each is mixed and taken out of the device for example, when the emission colors of both are complementary to each other, the light-emitting device can emit white light. Considering the reliability of the light-emitting device, it is preferable that the emission peak wavelength of the light-emitting material included in the light-emitting layer 120 is shorter than that of the light-emitting material included in the light-emitting layer 170.

[0219] Note that the light-emitting unit 106, the light-emitting unit 108, and the charge generation layer 115 can be formed by a vapor deposition method ( including vacuum vapor deposition), an inkjet method, a coating method, a gravure printing method, or the like. can be done.

[0220] As described above, the configuration shown in this embodiment can be appropriately combined with the configurations shown in other embodiments and used .

[0221] (Embodiment 3) In this embodiment, an example of a light-emitting element having a configuration different from the configurations shown in Embodiment 1 and Embodiment 2 will be described below with reference to FIGS. 5 to 8.

[0222] <Example of the Configuration of the Light-Emitting Element 1> FIGS. 5(A) and 5(B) are cross-sectional views showing a light-emitting element according to an aspect of the present invention. In FIGS. 5(A) and 5(B), portions having the same functions as those denoted by the reference numerals shown in FIG. 1(A) may be provided with the same hatch pattern, and the reference numerals may be omitted. Also, portions having the same functions may be denoted by the same reference numerals, and detailed descriptions thereof may be omitted.

[0223] The light-emitting elements 260a and 260b shown in FIGS. 5(A) and 5(B) may be bottom emission type light-emitting elements that extract light toward the substrate 200 side, or may be top emission type light-emitting elements that extract light in the direction opposite to the substrate 200. Note that one aspect of the present invention is not limited to this, and the light-emitting element may be a dual emission type light-emitting element that extracts the light emitted by the light-emitting element both above and below the substrate 200.

[0224] When the light-emitting elements 260a and 260b are of the bottom emission type, the electrode 1 01 preferably has a function of transmitting light. Also, the electrode 102 preferably has a function of reflecting light. Alternatively, when the light-emitting elements 260a and 260b are of the top emission type, the electrode 101 preferably has a function of reflecting light. ​ In addition, the electrode 102 preferably has a function of transmitting light.

[0225] The light emitting element 260a and the light emitting element 260b are formed by providing an electrode 101 and an electrode 102 on a substrate 200. In addition, between the electrode 101 and the electrode 102, a light-emitting layer 123B and a light-emitting layer 123 G and a light-emitting layer 123R. Also, the light-emitting layer 123 has a hole injection layer 111, a hole transport layer 112, It has an electron transport layer 118 and an electron injection layer 119 .

[0226] In addition, the light-emitting element 260b includes, as a part of the configuration of the electrode 101, a conductive layer 101a and a conductive The conductive layer 101b is located above the conductive layer 101a, and the conductive layer 101c is located below the conductive layer 101a. That is, in the light emitting element 260b, the conductive layer 101a is made up of the conductive layer 101b and the conductive layer 101c. It has a sandwiched electrode 101 configuration.

[0227] In the light emitting element 260b, the conductive layer 101b and the conductive layer 101c are made of different materials. The electrodes 101 may be sandwiched between the same conductive material. In the case where the electrode 101 is formed in such a manner that the pattern shape is formed by the etching process, This is preferred because it makes the synthesis easier.

[0228] In the light-emitting element 260b, the conductive layer 101b or the conductive layer 101c A configuration having only one of them may be used.

[0229] The conductive layers 101a, 101b, and 101c of the electrode 101 are The same configuration and material as the electrode 101 or the electrode 102 shown in the first embodiment can be used. Cut.

[0230] In FIGS. 5(A) and 5(B), a partition wall 145 is provided between a region 221B sandwiched between an electrode 101 and an electrode 102, a region 221G, and a region 221R. The partition wall 145 has insulating properties. The partition wall 145 covers an end portion of the electrode 101 and has an opening that overlaps with the electrode. By providing the partition wall 145, the electrodes 101 on the substrate 200 in each region can be separated into island shapes respectively.

[0231] Note that the light-emitting layer 123B and the light-emitting layer 123G may have overlapping regions with each other in a region overlapping with the partition wall 145. Alternatively, the light-emitting layer 123G and the light-emitting layer 123R may have overlapping regions with each other in a region overlapping with the partition wall 145. Or, the light-emitting layer 123R and the light-emitting layer 123B may have overlapping regions with each other in a region overlapping with the partition wall 145.

[0232] The partition wall 145 only needs to be insulating and can be formed using an inorganic material or an organic material. Examples of the inorganic material include silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, aluminum oxide, aluminum nitride, etc. Examples of the organic material include photosensitive resin materials such as acrylic resin or polyimide resin.

[0233] Note that a silicon oxynitride film refers to a film having a higher oxygen content than nitrogen in its composition, preferably a film containing oxygen in the range of 55 atomic % or more and 65 atomic % or less, nitrogen in the range of 1 atomic % or more and 20 atomic % or less, silicon in the range of 25 atomic % or more and 35 atomic % or less, and hydrogen in the range of 0.1 atomic % or more and 10 atomic % or less. A silicon nitride oxide film refers to a film having a higher nitrogen content than oxygen in its composition. ​​​​​​​​​​​​Refers to a film with a high element content, preferably a film containing nitrogen in the concentration range of 55 atomic % or more and 65 atomic % or less, oxygen in the range of 1 atomic % or more and 20 atomic % or less, silicon in the range of 25 atomic % or more and 35 atomic % or less, and hydrogen in the range of 0.1 atom % or more and 10 atomic % or less.

[0234] In addition, the light-emitting layer 123R, the light-emitting layer 123G, and the light-emitting layer 123B preferably each have a light-emitting material having a function of presenting a different color. For example, by having a light-emitting material in the light-emitting layer 123R that has a function of presenting red, the region 221R presents red light, and by having a light-emitting material in the light-emitting layer 123G that has a function of presenting green, the region 221G presents green light, and by having a light-emitting material in the light-emitting layer 123B that has a function of presenting blue, the region 2 21B presents blue light. By using the light-emitting element 260a or the light-emitting element 260b having such a configuration for the pixel of the display device, a display device capable of full-color display can be manufactured. Also, the film thicknesses of the respective light-emitting layers may be the same or different from each other. Moreover, any one or more of the light-emitting layers 123B, 123G, and 123R preferably have the same configuration as the light-emitting layer 140 shown in Embodiment 1. By doing so, a light-emitting element with good luminous efficiency can be manufactured. Note that any one or more of the light-emitting layers 123B, 123G, and 123R may have a configuration in which two or more layers are stacked. As described above, at least one light-emitting layer is the light-emitting layer shown in Embodiment 1 and Embodiment 2

[0235]

[0236]

[0237]

[0237] Having a layer structure and using the light-emitting element 260a or the light-emitting element 260b having the light-emitting layer for the pixel of the display device, a display device with high luminous efficiency can be manufactured. That is, the display device having the light-emitting element 260a or the light-emitting element 260b can reduce power consumption.

[0238] Note that by providing an optical element (for example, a color filter, a polarizing plate, an antireflection film, etc.) in the light extraction direction of the electrode for extracting light, the color purity of the light-emitting element 260a and the light-emitting element 260b can be improved. Therefore, the color purity of the display device having the light-emitting element 260a or the light-emitting element 260b can be enhanced. Alternatively, the external light reflection of the light-emitting element 260a and the light-emitting element 260b can be reduced. Therefore, the contrast ratio of the display device having the light-emitting element 260a or the light-emitting element 260b can be increased.

[0239] Note that for other configurations of the light-emitting element 260a and the light-emitting element 260b, the configurations of the light-emitting elements in Embodiment 1 and Embodiment 2 may be referred to.

[0240] <Configuration Example 2 of Light-Emitting Element> Next, a configuration example different from the light-emitting element shown in FIGS. 5(A) and 5(B) will be described below with reference to FIGS. 6(A) and 6(B).

[0241] FIGS. 6(A) and 6(B) are cross-sectional views showing a light-emitting element according to an aspect of the present invention. In FIGS. 6(A) and 6(B), portions having the same functions as the reference numerals shown in FIGS. 5(A) and 5(B) may have the same hatch pattern and the reference numerals may be omitted. Also, portions having the same functions may be given the same reference numerals, and the detailed description thereof may be omitted.

[0242] ​​​​​​ Figures 6(A) and (B) are configuration examples of a light-emitting element having a light-emitting layer between a pair of electrodes. Figure 6 (A) shows a top-emission type light-emitting element 262a that emits light in a direction opposite to the substrate 200, and the light-emitting element 262b shown in Figure 6 (B) is a bottom-emission type light-emitting element that emits light toward the substrate 200 side. However, one aspect of the present invention is not limited to this, and it may be a dual-emission type that emits the light emitted by the light-emitting element to both above and below the substrate 200 on which the light-emitting element is formed. The light-emitting element 262a and the light-emitting element 262b have an electrode 101, an electrode 102 on the substrate 200, an electrode 103, and an electrode 104. Also, between the electrode 101 and the electrode 102, and

[0243] between the electrode 102 and the electrode 103, and between the electrode 102 and the electrode 104, there are at least a light-emitting layer 170, a light-emitting layer 190, and a charge generation layer 115. Also, a hole injection layer 111 and a hole transport layer 112, an electron transport layer 113, an electron injection layer 114, a hole injection layer 116 and a hole transport layer 117, an electron transport layer 118, and an electron injection layer 119.

[0244] Also, the electrode 101 has a conductive layer 101a and a conductive layer 101b in contact with the conductive layer 101a. Also, the electrode 103 has a conductive layer 103a and a conductive layer 103b in contact with the conductive layer 103a. The electrode 104 has a conductive layer 104a and a conductive layer 104b in contact with the conductive layer 104a.

[0245] The light-emitting element 262a shown in Figure 6(A) and the light-emitting element 262b shown in Figure 6(B) are regions 222B sandwiched between the electrode 101 and the electrode 102, and regions sandwiched between the electrode 102 and the electrode 103 Between the region 222G and the region 222R sandwiched between the electrode 102 and the electrode 104, there is a partition wall 145. The partition wall 145 has insulating properties. The partition wall 145 covers the ends of the electrode 101, the electrode 103, and the electrode 104, and has an opening overlapping with the electrodes. By providing the partition wall 145, the electrodes on the substrate 200 in each region can be separated into island shapes respectively. It becomes possible.

[0246] In addition, as the charge generation layer 115, a material in which an electron acceptor is added to a hole transporting material, or a material in which an electron donor is added to an electron transporting material can be used to form it. When the conductivity of the charge generation layer 115 is as high as that of the pair of electrodes, carriers generated by the charge generation layer 115 may flow into adjacent pixels, causing adjacent pixels to emit light. Therefore, in order to suppress the improper emission of adjacent pixels, it is preferable that the charge generation layer 115 is formed of a material having a lower conductivity than the pair of electrodes. It is preferable.

[0247] In addition, the light-emitting element 262a and the light-emitting element 262b each have a substrate 220 having an optical element 224B, an optical element 224G, and an optical element 224R in the direction in which the light emitted from the region 222B, the region 222G, and the region 222R is extracted. The light emitted from each region is emitted to the outside of the light-emitting element through each optical element. That is, the light emitted from the region 222B is emitted through the optical element 224B, the light emitted from the region 222G is emitted through the optical element 224G, and the light emitted from the region 222R is emitted through the optical element 224R. It is emitted.

[0248] In addition, the optical element 224B, the optical element 224G, and the optical element 224R have a function of selectively transmitting light exhibiting a specific color from the incident light. For example, the light emitted from the region 222B emitted through the optical element 224B becomes light exhibiting blue, and the light emitted from the region 222G emitted through the optical element 224G becomes light exhibiting green, and the light emitted from the region 222R emitted through the optical element 224R becomes light exhibiting red. For the optical element 224R, the optical element 224G, and the optical element 224B, for example, a colored layer ( also referred to as a color filter), a band-pass filter, a multilayer film filter, etc. can be applied. Further, a color conversion element can be applied to the optical element. The color conversion element is an optical element that converts incident light into light having a wavelength longer than the wavelength of the light. As the color conversion element, it is preferable that it is an element using quantum dots. By using quantum dots, the color reproducibility of the display device can be enhanced. For the optical element 224R, the optical element 224G, and the optical element 224B, for example, a colored layer ( also referred to as a color filter), a band-pass filter, a multilayer film filter, etc. can be applied. Further, a color conversion element can be applied to the optical element. The color conversion element is an optical element that converts incident light into light having a wavelength longer than the wavelength of the light. As the color conversion element, it is preferable that it is an element using quantum dots. By using quantum dots, the color reproducibility of the display device can be enhanced.

[0249] Note that one or more other optical elements may be provided on the optical element 224R, the optical element 224G, and the optical element 224B. As the other optical element, for example, a circular polarizing plate, an antireflection film, etc. can be provided. If a circular polarizing plate is provided on the side from which the light emitted from the light-emitting element of the display device is taken out, it is possible to prevent the phenomenon that the light incident from the outside of the display device is reflected inside the display device and emitted to the outside. Further, by providing an antireflection film, the external light reflected on the surface of the display device can be weakened. Thereby, the light emission emitted from the display device can be clearly observed. also referred to as a color filter), a band-pass filter, a multilayer film filter, etc. can be applied. Further, a color conversion element can be applied to the optical element. The color conversion element is an optical element that converts incident light into light having a wavelength longer than the wavelength of the light. As the color conversion element, it is preferable that it is an element using quantum dots. By using quantum dots, the color reproducibility of the display device can be enhanced. also referred to as a color filter), a band-pass filter, a multilayer film filter, etc. can be applied. Further, a color conversion element can be applied to the optical element. The color conversion element is an optical element that converts incident light into light having a wavelength longer than the wavelength of the light. As the color conversion element, it is preferable that it is an element using quantum dots. By using quantum dots, the color reproducibility of the display device can be enhanced. also referred to as a color filter), a band-pass filter, a multilayer film filter, etc. can be applied. Further, a color conversion element can be applied to the optical element. The color conversion element is an optical element that converts incident light into light having a wavelength longer than the wavelength of the light. As the color conversion element, it is preferable that it is an element using quantum dots. By using quantum dots, the color reproducibility of the display device can be enhanced. also referred to as a color filter), a band-pass filter, a multilayer film filter, etc. can be applied. Further, a color conversion element can be applied to the optical element. The color conversion element is an optical element that converts incident light into light having a wavelength longer than the wavelength of the light. As the color conversion element, it is preferable that it is an element using quantum dots. By using quantum dots, the color reproducibility of the display device can be enhanced. also referred to as a color filter), a band-pass filter, a multilayer film filter, etc. can be applied. Further, a color conversion element can be applied to the optical element. The color conversion element is an optical element that converts incident light into light having a wavelength longer than the wavelength of the light. As the color conversion element, it is preferable that it is an element using quantum dots. By using quantum dots, the color reproducibility of the display device can be enhanced.

[0250] Note that one or more other optical elements may be provided on the optical element 224R, the optical element 224G, and the optical element 224B. As the other optical element, for example, a circular polarizing plate, an antireflection film, etc. can be provided. If a circular polarizing plate is provided on the side from which the light emitted from the light-emitting element of the display device is taken out, it is possible to prevent the phenomenon that the light incident from the outside of the display device is reflected inside the display device and emitted to the outside. Further, by providing an antireflection film, the external light reflected on the surface of the display device can be weakened. Thereby, the light emission emitted from the display device can be clearly observed. Note that one or more other optical elements may be provided on the optical element 224R, the optical element 224G, and the optical element 224B. As the other optical element, for example, a circular polarizing plate, an antireflection film, etc. can be provided. If a circular polarizing plate is provided on the side from which the light emitted from the light-emitting element of the display device is taken out, it is possible to prevent the phenomenon that the light incident from the outside of the display device is reflected inside the display device and emitted to the outside. Further, by providing an antireflection film, the external light reflected on the surface of the display device can be weakened. Thereby, the light emission emitted from the display device can be clearly observed. Note that one or more other optical elements may be provided on the optical element 224R, the optical element 224G, and the optical element 224B. As the other optical element, for example, a circular polarizing plate, an antireflection film, etc. can be provided. If a circular polarizing plate is provided on the side from which the light emitted from the light-emitting element of the display device is taken out, it is possible to prevent the phenomenon that the light incident from the outside of the display device is reflected inside the display device and emitted to the outside. Further, by providing an antireflection film, the external light reflected on the surface of the display device can be weakened. Thereby, the light emission emitted from the display device can be clearly observed. Note that one or more other optical elements may be provided on the optical element 224R, the optical element 224G, and the optical element 224B. As the other optical element, for example, a circular polarizing plate, an antireflection film, etc. can be provided. If a circular polarizing plate is provided on the side from which the light emitted from the light-emitting element of the display device is taken out, it is possible to prevent the phenomenon that the light incident from the outside of the display device is reflected inside the display device and emitted to the outside. Further, by providing an antireflection film, the external light reflected on the surface of the display device can be weakened. Thereby, the light emission emitted from the display device can be clearly observed. Note that one or more other optical elements may be provided on the optical element 224R, the optical element 224G, and the optical element 224B. As the other optical element, for example, a circular polarizing plate, an antireflection film, etc. can be provided. If a circular polarizing plate is provided on the side from which the light emitted from the light-emitting element of the display device is taken out, it is possible to prevent the phenomenon that the light incident from the outside of the display device is reflected inside the display device and emitted to the outside. Further, by providing an antireflection film, the external light reflected on the surface of the display device can be weakened. Thereby, the light emission emitted from the display device can be clearly observed. Note that one or more other optical elements may be provided on the optical element 224R, the optical element 224G, and the optical element 224B. As the other optical element, for example, a circular polarizing plate, an antireflection film, etc. can be provided. If a circular polarizing plate is provided on the side from which the light emitted from the light-emitting element of the display device is taken out, it is possible to prevent the phenomenon that the light incident from the outside of the display device is reflected inside the display device and emitted to the outside. Further, by providing an antireflection film, the external light reflected on the surface of the display device can be weakened. Thereby, the light emission emitted from the display device can be clearly observed. Note that one or more other optical elements may be provided on the optical element 224R, the optical element 224G, and the optical element 224B. As the other optical element, for example, a circular polarizing plate, an antireflection film, etc. can be provided. If a circular polarizing plate is provided on the side from which the light emitted from the light-emitting element of the display device is taken out, it is possible to prevent the phenomenon that the light incident from the outside of the display device is reflected inside the display device and emitted to the outside. Further, by providing an antireflection film, the external light reflected on the surface of the display device can be weakened. Thereby, the light emission emitted from the display device can be clearly observed.

[0251] In FIGS. 6(A) and 6(B), the light emitted from each region through each optical element is represented as light exhibiting blue (B), light exhibiting green (G), and light exhibiting red (R), respectively, and is schematically illustrated by dashed arrows.

[0252] In addition, a light-shielding layer 223 is provided between the optical elements. The light-shielding layer 223 has a function of shielding light emitted from adjacent regions. Note that a configuration without the light-shielding layer 223 may also be employed.

[0253] The light-shielding layer 223 has a function of suppressing reflection of external light. Alternatively, the light-shielding layer 223 has a function of preventing color mixing of light emitted from adjacent light-emitting elements. As the light-shielding layer 223, a metal, a resin containing a black pigment, carbon black, a metal oxide, a composite oxide containing a solid solution of a plurality of metal oxides, or the like can be used.

[0254] Note that the optical element 224B and the optical element 224G may have an overlapping region with each other in a region overlapping with the light-shielding layer 223. Alternatively, the optical element 224G and the optical element 224R may have an overlapping region with each other in a region overlapping with the light-shielding layer 223. Alternatively, the optical element 224R and the optical element 224B may have an overlapping region with each other in a region overlapping with the light-shielding layer 223.

[0255] In addition, as the configuration of the substrate 200 and the substrate 220 having the optical elements, Embodiment 1 may be referred to.

[0256] Furthermore, the light-emitting element 262a and the light-emitting element 262b have a microcavity structure.

[0257] ≪Microcavity Structure≫ The light emitted from the light-emitting layer 170 and the light-emitting layer 190 resonates between a pair of electrodes (for example, electrode 10 1 and electrode 102). Also, the light-emitting layer 170 and the light-emitting layer 190 are formed at positions where the light of a desired wavelength among the emitted light is enhanced. For example, by adjusting the optical distance from the reflection region of the electrode 101 to the light-emitting region of the light-emitting layer 170 and the optical distance from the reflection region of the electrode 102 to the light-emitting region of the light-emitting layer 170, the light of a desired wavelength among the light emitted from the light-emitting layer 170 can be enhanced. Also, by adjusting the optical distance from the reflection region of the electrode 101 to the light-emitting region of the light-emitting layer 190 and the optical distance from the reflection region of the electrode 102 to the light-emitting region of the light-emitting layer 190, the light of a desired wavelength among the light emitted from the light-emitting layer 190 can be enhanced. That is, in the case of a light-emitting element in which a plurality of light-emitting layers (here, the light-emitting layer 170 and the light-emitting layer 190) are stacked, it is preferable to optimize the respective optical distances of the light-emitting layer 170 and the light-emitting layer 190. 190) are stacked, it is preferable to optimize the respective optical distances of the light-emitting layer 170 and the light-emitting layer 190. 190) are stacked, it is preferable to optimize the respective optical distances of the light-emitting layer 170 and the light-emitting layer 190. It is preferable to optimize the optical distance of each of the light-emitting layer 170 and the light-emitting layer 190.

[0258] Also, in the light-emitting element 262a and the light-emitting element 262b, by adjusting the thickness of the conductive layer (conductive layer 1 01b, conductive layer 103b, and conductive layer 104b) in each region, the light of a desired wavelength among the light presented from the light-emitting layer 170 and the light-emitting layer 190 can be enhanced. Note that by making at least one of the thicknesses of the hole injection layer 111 and the hole transport layer 112 different in each region, the light presented from the light-emitting layer 170 and the light-emitting layer 190 may be enhanced.

[0259] For example, in the electrodes 101 to 104, when the refractive index of the conductive material having a function of reflecting light is smaller than the refractive index of the light-emitting layer 170 or the light-emitting layer 190, the electrode ​​​​​​Adjust the film thickness of the conductive layer 101b of 101 such that the optical distance between the electrode 101 and the electrode 102 is m B λ B / 2 (m B is a natural number, λ B is the wavelength of the light to be enhanced in the region 222B, respectively). Adjust in this way. Similarly, adjust the film thickness of the conductive layer 103b of the electrode 103 such that the optical distance between the electrode 103 and the electrode 102 is m G λ G / 2 (m G is a natural number, λ G is the wavelength of the light to be enhanced in the region 222G respectively). Adjust in this way. Furthermore, adjust the film thickness of the conductive layer 104b of the electrode 104 such that the optical distance between the electrode 104 and the electrode 102 is m R λ R / 2 (m R is a natural number, λ R is the wavelength of the light to be enhanced in the region 222R, respectively). Adjust in this way.

[0260] In addition, when it is difficult to precisely determine the reflection regions of the electrodes 101 to 104, by assuming any region of the electrodes 101 to 104 as the reflection region, the optical distance for enhancing the light emitted from the light emitting layer 170 or the light emitting layer 190 may be derived. Also, when it is difficult to precisely determine the light emitting regions of the light emitting layer 170 and the light emitting layer 190, by assuming any region of the light emitting layer 170 and the light emitting layer 190 as the light emitting region, the optical distance for enhancing the light emitted from the light emitting layer 170 and the light emitting layer 190 may be derived.

[0261] As described above, by providing the microcavity structure and adjusting the optical distance between the pair of electrodes in each region, scattering and absorption of light near each electrode can be suppressed, and a high light extraction efficiency can be realized.

[0262] In the above configuration, it is preferable that the conductive layers 101b, 103b, and 104b have a function of transmitting light. Further, the materials constituting the conductive layers 101b, 103b, and 104b may be the same as or different from each other. When the same material is used for the conductive layers 101b, 103b, and 104b, pattern formation by an etching process in the formation process of the electrodes 101, 103, and 104 is facilitated, which is preferable. Further, the conductive layers 101b, 103b, and 104b may each have a configuration in which two or more layers are laminated. Since the light-emitting element 262a shown in FIG. 6(A) is a top-emitting type light-emitting element, it is preferable that the conductive layers 101a, 103a, and 104a have a function of reflecting light. Further, it is preferable that the electrode 102 has a function of transmitting light and a function of reflecting light. Since the light-emitting element 262b shown in FIG. 6(B) is a bottom-emitting type light-emitting element, it is preferable that the conductive layers 101a, 103a, and 104a have a function of transmitting light and a function of reflecting light. Further, it is preferable that the electrode 102 has a function of reflecting light. In the light-emitting elements 262a and 262b, the same material may be used for the conductive layers 101a, 103a, or 104a, or different materials may be used. When the same material is used for the conductive layers 101a, 103a, and 104a, In the light-emitting elements 262a and 262b, the same material may be used for the conductive layers 101a, 103a, or 104a, or different materials may be used. When the same material is used for the conductive layers 101a, 103a, and 104a, In the light-emitting elements 262a and 262b, the same material may be used for the conductive layers 101a, 103a, or 104a, or different materials may be used. When the same material is used for the conductive layers 101a, 103a, and 104a, In the light-emitting elements 262a and 262b, the same material may be used for the conductive layers 101a, 103a, or 104a, or different materials may be used. When the same material is used for the conductive layers 101a, 103a, and 104a,

[0263] Since the light-emitting element 262a shown in FIG. 6(A) is a top-emitting type light-emitting element, it is preferable that the conductive layers 101a, 103a, and 104a have a function of reflecting light. Further, it is preferable that the electrode 102 has a function of transmitting light and a function of reflecting light. Since the light-emitting element 262a shown in FIG. 6(A) is a top-emitting type light-emitting element, it is preferable that the conductive layers 101a, 103a, and 104a have a function of reflecting light. Further, it is preferable that the electrode 102 has a function of transmitting light and a function of reflecting light. Since the light-emitting element 262a shown in FIG. 6(A) is a top-emitting type light-emitting element, it is preferable that the conductive layers 101a, 103a, and 104a have a function of reflecting light. Further, it is preferable that the electrode 102 has a function of transmitting light and a function of reflecting light. Since the light-emitting element 262a shown in FIG. 6(A) is a top-emitting type light-emitting element, it is preferable that the conductive layers 101a, 103a, and 104a have a function of reflecting light. Further, it is preferable that the electrode 102 has a function of transmitting light and a function of reflecting light.

[0264] Since the light-emitting element 262b shown in FIG. 6(B) is a bottom-emitting type light-emitting element, it is preferable that the conductive layers 101a, 103a, and 104a have a function of transmitting light and a function of reflecting light. Further, it is preferable that the electrode 102 has a function of reflecting light. Since the light-emitting element 262b shown in FIG. 6(B) is a bottom-emitting type light-emitting element, it is preferable that the conductive layers 101a, 103a, and 104a have a function of transmitting light and a function of reflecting light. Further, it is preferable that the electrode 102 has a function of reflecting light. Since the light-emitting element 262b shown in FIG. 6(B) is a bottom-emitting type light-emitting element, it is preferable that the conductive layers 101a, 103a, and 104a have a function of transmitting light and a function of reflecting light. Further, it is preferable that the electrode 102 has a function of reflecting light. Since the light-emitting element 262b shown in FIG. 6(B) is a bottom-emitting type light-emitting element, it is preferable that the conductive layers 101a, 103a, and 104a have a function of transmitting light and a function of reflecting light. Further, it is preferable that the electrode 102 has a function of reflecting light.

[0265] In the light-emitting elements 262a and 262b, the same material may be used for the conductive layers 101a, 103a, or 104a, or different materials may be used. When the same material is used for the conductive layers 101a, 103a, and 104a, In the light-emitting elements 262a and 262b, the same material may be used for the conductive layers 101a, 103a, or 104a, or different materials may be used. When the same material is used for the conductive layers 101a, 103a, and 104a, In the light-emitting elements 262a and 262b, the same material may be used for the conductive layers 101a, 103a, or 104a, or different materials may be used. When the same material is used for the conductive layers 101a, 103a, and 104a, The manufacturing costs of the sub-elements 262a and the light-emitting element 262b can be reduced. Note that the conductive layer 101a, the conductive layer 103a, and the conductive layer 104a may each have a structure in which two or more layers are stacked.

[0266] Also, at least one of the light-emitting layers 170 and 190 in the light-emitting element 262a and the light-emitting element 262b preferably has at least one of the configurations shown in Embodiment 1 and Embodiment 2. By doing so, a light-emitting element exhibiting high luminous efficiency can be fabricated.

[0267] Further, the light-emitting layers 170 and 190 may each have a structure in which one or both are stacked with two layers, such as the light-emitting layer 190a and the light-emitting layer 190b. By using two types of light-emitting materials having functions of exhibiting different colors, such as a first compound and a second compound, in the two-layer light-emitting layer, a plurality of emissions can be obtained simultaneously. In particular, it is preferable to select the light-emitting materials used for each light-emitting layer so that the emissions exhibited by the light-emitting layer 170 and the light-emitting layer 190 result in white light.

[0268] Moreover, the light-emitting layer 170 or the light-emitting layer 190 may each have a structure in which one or both are stacked with three or more layers, and may include a layer having no light-emitting material.

[0269] As described above, by using the light-emitting element 262a or the light-emitting element 262b having at least one of the configurations of the light-emitting layers shown in Embodiment 1 and Embodiment 2 for the pixels of the display device, a display device with high luminous efficiency can be fabricated. That is, a display device having the light-emitting element 262a or the light-emitting element 262b can reduce power consumption.

[0270] ​​​​​​​​​​​​​ Regarding other configurations of the light-emitting elements 262a and 262b, refer to the configurations of the light-emitting element 260a or the light-emitting element 260b, or the light-emitting elements shown in Embodiment 1 and Embodiment 2. It suffices to consider them.

[0271] <Fabrication method of light-emitting element> Next, a method for fabricating a light-emitting element according to an aspect of the present invention will be described below with reference to FIGS. 7 and 8. Here, a method for fabricating the light-emitting element 262a shown in FIG. 6(A) will be described.

[0272] FIGS. 7 and 8 are cross-sectional views for explaining a method for fabricating a light-emitting element according to an aspect of the present invention.

[0273] The method for fabricating the light-emitting element 262a described below has seven steps from the first to the seventh.

[0274] <<First step>> The first step is a step of forming electrodes of the light-emitting element (specifically, the conductive layer 101a constituting the electrode 101, the conductive layer 103a constituting the electrode 103, and the conductive layer 104a constituting the electrode 104) on the substrate 200 (see FIG. 7(A)).

[0275] In the present embodiment, a conductive layer having a function of reflecting light is formed on the substrate 200, and the conductive layer 101a, the conductive layer 103a, and the conductive layer 104a are formed by processing the conductive layer into a desired shape. As the conductive layer having the function of reflecting light, an alloy film of silver, palladium, and copper (Ag-Pd-Cu film, also referred to as APC) is used. In this way, the conductive layer 101a, the conductive layer 103a, and the conductive layer 104a are formed by a process of processing the same conductive layer. and the conductive layer 104a are formed in a process of processing the same conductive layer. ​​​​​​This is preferable because it is possible to reduce the manufacturing cost.

[0276] It should be noted that a number of transistors may be formed on the substrate 200 before the first step. In addition, the plurality of transistors, the conductive layer 101a, the conductive layer 103a, and the conductive layer 104a may be electrically connected to each other.

[0277] <<Second step>> In the second step, a light-transmitting layer 101b having a function of transmitting light is formed on the conductive layer 101a constituting the electrode 101. The conductive layer 101b is placed on the conductive layer 103a that constitutes the electrode 103. The conductive layer 103b is placed on the conductive layer 104a of the electrode 104. This is a step of forming a conductive layer 104b (see FIG. 7(B)).

[0278] In this embodiment, the conductive layers 101a and 103a, which have a function of reflecting light, 104a, and 101b, respectively, are provided on the conductive layers 101b, 103b, and By forming 104b, the electrodes 101, 103, and 104 are formed. The conductive layers 101b, 103b, and 104b are formed using ITSO films.

[0279] The conductive layers 101b, 103b, and 104b having a function of transmitting light are formed multiple times. By forming the microcapsules in several steps, it is possible to form the microcapsules in each area. The conductive layers 101b, 103b, and 104b can be formed to a thickness that provides a void structure. Cut.

[0280] <Third step> The third step is to form the partition walls 145 that cover the ends of the electrodes of the light-emitting element. See Figure 7(C).

[0281] The partition wall 145 has an opening so as to overlap with the electrode. The conductive film exposed by the opening functions as the anode of the light-emitting element. In the present embodiment, polyimide resin is used as the partition wall 145.

[0282] In addition, in the first to third steps, since there is no risk of damaging the EL layer (layer containing an organic compound), various film-forming methods and microfabrication techniques can be applied. In the present embodiment a reflective conductive layer is formed using a sputtering method, and a pattern is formed on the conductive layer using a lithography method, and then a dry etching method or a wet etching method is used to process the conductive layer into an island shape, thereby forming the conductive layer 101a constituting the electrode 101, the conductive layer 103a constituting the electrode 10 3, and the conductive layer 104a constituting the electrode 104. Thereafter, a conductive film having transparency is formed using a sputtering method, a pattern is formed on the transparent conductive film using a lithography method, and then a wet etching method is used to process the transparent conductive film into an island shape to form the electrodes 101, 103, and 104. Thereafter, a conductive film having transparency is formed using a sputtering method, a pattern is formed on the transparent conductive film using a lithography method, and then a wet etching method is used to process the transparent conductive film into an island shape to form the electrodes 101, 103, and 104. Thereafter, a conductive film having transparency is formed using a sputtering method, a pattern is formed on the transparent conductive film using a lithography method, and then a wet etching method is used to process the transparent conductive film into an island shape to form the electrodes 101, 103, and 104.

[0283] <<Fourth Step>> The fourth step is a step of forming a hole injection layer 111, a hole transport layer 112, a light-emitting layer 190, an electron transport layer 113, an electron injection layer 114, and a charge generation layer 115 (see Fig. 8(A)). ).

[0284] The hole injection layer 111 can be formed by co-evaporating a hole-transporting material and a material containing an acceptor substance. Note that co-evaporation means evaporating a plurality of different substances separately and simultaneously depositing them. The hole transport layer 112 is a deposition method in which a hole It can be formed by vapor deposition of a transport material.

[0285] The light-emitting layer 190 may be purple, blue, blue-green, green, yellow-green, yellow, orange, or red. The light-emitting layer is formed by depositing at least one luminescent guest material selected from the following: The guest material can be an organic material that emits fluorescence or phosphorescence. In addition, the light-emitting layer having the structure shown in the embodiment 1 and the embodiment 2 can be used. It is preferable that the light-emitting layer 190 is made of two layers. The light-emitting layers preferably contain light-emitting materials that emit light of different colors.

[0286] The electron transport layer 113 can be formed by evaporating a substance having a high electron transport property. The electron injection layer 114 can be formed by evaporating a material having a high electron injection property. It is possible.

[0287] The charge generating layer 115 is made of a material having a hole transporting property to which an electron acceptor is added. or a material in which an electron donor is added to an electron transporting material. It can be formed with.

[0288] <The fifth step> The fifth step is to deposit the hole injection layer 116, the hole transport layer 117, the light emitting layer 170, the electron transport layer 117, and the hole transport layer 118. This is a step of forming a layer 118, an electron injection layer 119, and an electrode 102 (see FIG. 8B).

[0289] The hole injection layer 116 is formed of the same material and in the same manner as the hole injection layer 111 described above. It can be formed. Further, as the hole transport layer 117, it can be formed by the same material and the same method as the hole transport layer 11 2 shown above.

[0290] As the light emitting layer 170, at least one guest material that exhibits light emission selected from purple, blue, cyan, green, yellow - green, yellow, orange, or red is deposited to form it. As the guest material, a luminescent organic compound that exhibits fluorescence or phosphorescence can be used. Also, it is preferable to use the configuration of the light emitting layer shown in Embodiment 1 and Embodiment 2. Note that at least one of the light emitting layer 170 and the light emitting layer 190 preferably has the configuration of the light emitting layer shown in Embodiment 1. Also, the light emitting layer 170 and the light emitting layer 1 90 preferably have a luminescent organic compound having a function of exhibiting different light emissions from each other.

[0291] As the electron transport layer 118, it can be formed by the same material and the same method as the electron transport layer 113 shown above. Also, as the electron injection layer 119, it can be formed by the same material and the same method as the electron injection layer 11 4 shown above.

[0292] As the electrode 102, it can be formed by laminating a reflective conductive film and a transparent conductive film. Also, the electrode 102 may have a single - layer structure or a laminated structure.

[0293] Through the above steps, a light - emitting device having regions 222 B, region 222G, and region 222R is formed on the substrate 200 on the electrodes 101, 103, and 104, respectively.

[0294] ≪Sixth step≫ The sixth step is to form a light-shielding layer 223, optical elements 224B, 224G, and 224R on the substrate 220 (see Fig. 8(C)). G, and optical element 224R (see Fig. 8(C)).

[0295] As the light-shielding layer 223, a resin film containing a black pigment is formed in a desired region. Then, on the substrate 220 and the light-shielding layer 223, optical elements 224B, 224G, and 2 24R are formed. As the optical element 224B, a resin film containing a blue pigment is formed in a desired region. Also, as the optical element 224G, a resin film containing a green pigment is formed in a desired region. Also, as the optical element 224R, a resin film containing a red pigment is formed in a desired region. is formed.

[0296] ≪Seventh step≫ The seventh step is to bond the light-emitting element formed on the substrate 200 and the light-shielding layer 223, optical elements 224B, 224G, and 224R formed on the substrate 220, and seal them using a sealing material (not shown).

[0297] Through the above steps, the light-emitting element 262a shown in Fig. 6(A) can be formed.

[0298] Note that the configuration shown in this embodiment can be appropriately combined with the configurations shown in other embodiments and used.

[0299] (Embodiment 4) In this embodiment, a display device according to an aspect of the present invention will be described with reference to Figs. 9 to 17 is described.

[0300] <Configuration example 1 of the display device> Fig. 9(A) is a top view showing the display device 600, and Fig. 9(B) is a dashed line A-B in Fig. 9(A) , and a cross-sectional view taken along the dashed-dotted line C-D. The display device 600 includes a drive circuit section (signal lines drive circuit section 601 and scan line drive circuit section 603), and a pixel section 602. Note that , the signal line drive circuit section 601, the scan line drive circuit section 603, and the pixel section 602 have the function of controlling the light emission of the light-emitting element.

[0301] Further, the display device 600 includes an element substrate 610, a sealing substrate 604, a sealing material 605, a region 607 surrounded by the sealing material 605, a routing wiring 608, and an FPC 609. It has.

[0302] Note that the routing wiring 608 is a wiring for transmitting signals input to the signal line drive circuit section 601 and the scan line drive circuit section 603, and receives a video signal, a clock signal, a start signal, a reset signal, etc. from the FPC 609 which is an external input terminal. Note that although only the FPC 609 is shown here, a printed wiring board (PWB: Pri nted Wiring Board) may be attached to the FPC 609.

[0303] Further, the signal line drive circuit section 601 is formed of a CMOS circuit combining an N-channel transistor 623 and a P-channel transistor 624. Note that the signal line drive circuit section 601 or the scan line drive circuit section 603 can use various CMOS circuits, PMOS circuits, or NMOS circuits. Also, in this embodiment, a display device in which a driver formed with a drive circuit section on a substrate and pixels are provided on the same surface is shown, but this is not necessarily required, and the drive circuit section can be formed outside instead of on the substrate.

[0304] In addition, the pixel portion 602 includes a transistor 611 for switching, a transistor 612 for current control, and a lower electrode 613 electrically connected to the drain of the transistor 612 for current control. The lower electrode 613 has a partition wall 614 formed to cover its end. As the partition wall 614, a positive photosensitive acrylic resin film can be used.

[0305] In addition, in order to improve the coating property, a curved surface having a curvature is formed at the upper end or the lower end of the partition wall 614. For example, when positive photosensitive acrylic is used as the material of the partition wall 614, it is preferable to provide a curved surface having a radius of curvature (0.2 μm or more and 3 μm or less) only at the upper end of the partition wall 614. Also, as the partition wall 614, either a negative photosensitive resin or a positive photosensitive resin can be used.

[0306] Note that the structure of the transistors (transistors 611, 612, 623, 624) is not particularly limited. For example, a staggered transistor may be used. Also, there is no particular limitation on the polarity of the transistors, and structures having N-channel and P-channel transistors, and structures consisting of only one of N-channel transistors or P-channel transistors may be used. Also, there is no particular limitation on the crystallinity of the semiconductor film used for the transistors. For example, an amorphous semiconductor film or a crystalline semiconductor film can be used. As the semiconductor material, group 14 (such as silicon) semiconductors, compound semiconductors (including oxide semiconductors), organic semiconductors, etc. can be used. As the transistor, for example, a transistor having an energy gap of 2 eV or more, preferably 2.5 eV or more, more preferably 3 eV By using the above oxide semiconductor, the off-current of the transistor can be reduced, which is preferable. Examples of the oxide semiconductor include In-Ga oxide, In-M-Zn oxide (where M represents , aluminum (Al), gallium (Ga), yttrium (Y), zirconium (Zr ), lanthanum (La), cerium (Ce), tin (Sn), hafnium (Hf), or neodymium (Nd)).

[0307] An EL layer 616 and an upper electrode 617 are respectively formed on the lower electrode 613. Note that the lower electrode 613 functions as an anode, and the upper electrode 617 functions as a cathode.

[0308] The EL layer 616 is formed by various methods such as vapor deposition using a vapor deposition mask, inkjet method, spin coating method, etc. Also, the material constituting the EL layer 616 may be a low molecular compound or a high molecular compound (including oligomers and dendrimers).

[0309] The lower electrode 613, the EL layer 616, and the upper electrode 617 form a light-emitting element 618. The light-emitting element 618 preferably has the configuration of the light-emitting element according to Embodiments 1 to 3. When a plurality of light-emitting elements are formed in the pixel portion, both the light-emitting element described in Embodiments 1 to 3 and the light-emitting element having other configurations may be included.

[0310] Also, 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 a region 607 surrounded by the element substrate 610, the sealing substrate 604, and the sealing material 605. The region 607 is filled with a filling material. ​ In addition to the case where an inert gas (such as nitrogen or argon) is filled, it may also be filled with an ultraviolet curable resin or a thermosetting resin that can be used for the sealing material 605. For example, PVC ( polyvinyl chloride)-based resin, acrylic-based resin, polyimide-based resin, epoxy-based resin, silicone-based resin, PVB (polyvinyl butyral)-based resin, or EVA (ethylene vinyl acetate)-based resin can be used. A recess is formed in the sealing substrate, and a desiccant is provided therein, which can suppress deterioration due to the influence of moisture and is a preferable configuration.

[0311] Also, an optical element 621 is provided below the sealing substrate 604 so as to overlap with the light emitting element 618. Further, a light shielding layer 622 is provided below the sealing substrate 604. As the optical element 621 and the light shielding layer 622, they may have the same configurations as the optical element and the light shielding layer shown in Embodiment 3, respectively.

[0312] Note that it is preferable to use an epoxy-based resin or glass frit for the sealing material 605. In addition, it is desirable that these materials are materials that hardly transmit moisture and oxygen. In addition to a glass substrate or a quartz substrate, as the material used for the sealing substrate 604, FRP (Fiber Reinforced Plastics), PVF (polyvinyl fluoride), polyester or a plastic substrate made of acrylic or the like can be used.

[0313] As described above, a display device having the light emitting element and the optical element described in Embodiments 1 to 3 can be obtained.

[0314] <Configuration Example 2 of Display Device> ​​Next, another example of the display device will be described with reference to FIGS. 10(A), 10(B), and 11. Note that FIGS. 10(A), 10(B), and 11 are cross-sectional views of the display device according to one embodiment of the present invention. .

[0315] In FIG. 10(A), a substrate 1001, an underlying insulating film 1002, a gate insulating film 1003, gate electrodes 1006, 1007, 1008, a first interlayer insulating film 1020, a second interlayer insulating film 10 21, a peripheral portion 1042, a pixel portion 1040, a drive circuit portion 1041, lower electrodes 10 24R, 1024G, 1024B of a light-emitting element, a partition wall 1025, an EL layer 1028, an upper electrode 1026 of the light-emitting element, a sealing layer 1029, a sealing substrate 1031, a sealing material 1032, etc. are shown. .

[0316] Also, in FIG. 10(A), as an example of an optical element, a colored layer (a red colored layer 1034R, a green colored layer 1034G, and a blue colored layer 1034B) is provided on a transparent base material 1033. Further, a light-shielding layer 1035 may be provided. The transparent base material 1033 provided with the colored layer and the light-shielding layer is aligned and fixed to the substrate 1001. Note that the colored layer and the light-shielding layer are covered with an overcoat layer 1036. Also, in FIG. 10(A), since the light transmitted through the colored layer becomes red, green, and blue, an image can be expressed by three-color pixels.

[0317] In FIG. 10(B), as an example of an optical element, an example is shown in which a colored layer (a red colored layer 1034R, a green colored layer 1034G, and a blue colored layer 1034B) is formed between the gate insulating film 1003 and the first interlayer insulating film 1020. Thus, the colored layer may be provided between the substrate 1001 and the sealing substrate 1031.

[0318] In FIG. 11, as an example of an optical element, a colored layer (a red colored layer 1034R, a green colored layer 1034G, and a blue colored layer 1034B) is shown as an example formed between a first interlayer insulating film 1020 and a second interlayer insulating film 1021. Thus, the colored layer may be provided between the substrate 1001 and the sealing substrate 1031.

[0319] Also, in the display device described above, a structure for extracting light (bottom emission type) is used on the side of the substrate 1001 on which the transistors are formed, but a structure for extracting light emission (top emission type) may be used on the side of the sealing substrate 1031.

[0320] <Example Configuration 3 of Display Device> An example of a cross-sectional view of a top emission type display device is shown in FIGS. 12(A) and 12(B). FIG. 12 (A) and (B) are cross-sectional views for explaining the display device according to an aspect of the present invention, and the drive circuit portion 1041, the peripheral portion 1042, etc. shown in FIGS. 10(A) and 10(B ) and FIG. 11 are omitted and illustrated.

[0321] In this case, a substrate that does not transmit light can be used as the substrate 1001. Until a connection electrode connecting the transistor and the anode of the light emitting element is fabricated, it is formed in the same manner as a bottom emission type display device Then, a third interlayer insulating film 1037 is formed so as to cover the electrode 1022. This insulating film may serve as a planarization film. The third interlayer insulating film 1037 can be formed using various other materials in addition to the same material as the second interlayer insulating film.

[0322] The lower electrodes 1024R, 1024G, and 1024B of the light emitting element are anodes here, but they may be cathodes. Also, a top emission type display as shown in FIGS. 12(A) and 12(B) ​ In the case of the device, the lower electrodes 1024R, 1024G, and 1024B preferably have a function of reflecting light. Further, an upper electrode 1026 is provided on the EL layer 1028. The upper electrode 1026 has a function of reflecting light and a function of transmitting light. A microcavity structure is adopted between the lower electrodes 1024R, 10 24G, 1024B and the upper electrode 1026, and it is preferable to increase the light intensity at a specific wavelength.

[0323] In the top emission structure as shown in Fig. 12(A), a sealing substrate 1031 provided with a coloring layer (red coloring layer 1034 R, green coloring layer 1034G, and blue coloring layer 1034B) can be used for sealing. A light-shielding layer 1035 may be provided on the sealing substrate 1031 so as to be located between pixels. Note that it is preferable to use a substrate having translucency as the sealing substrate 1031.

[0324] In Fig. 12(A), a configuration in which a plurality of light-emitting elements and coloring layers are provided for each of the plurality of light-emitting elements is illustrated, but the present invention is not limited thereto. For example, as shown in Fig. 12(B), a full-color display may be performed in three colors of red, green, and blue by providing a red coloring layer 1034R and a blue coloring layer 1034B without providing a green coloring layer. As shown in Fig. 12(A), when a configuration in which a light-emitting element and a coloring layer are provided for each of the light-emitting elements is adopted, an effect such as suppression of external light reflection can be obtained. On the other hand, as shown in Fig. 12(B), when a configuration in which a light-emitting element and a red coloring layer and a blue coloring layer are provided without providing a green coloring layer is adopted, since the energy loss of light emitted from the green light-emitting element is small, an effect such that the power consumption can be reduced can be obtained.

[0325] <Configuration Example 4 of Display Device> The display device shown above has a configuration with three-color (red, green, blue) sub-pixels, but it may also have a configuration with four-color (red, green, blue, yellow, or red, green, blue, white) sub-pixels. FIGS. 13 to 15 show the configuration of a display device having lower electrodes 1024R, 1024G, 1024B, and 1024Y. FIGS. 13(A)(B) and FIG. 14 show a structure (bottom emission type) in which light is extracted from the substrate 1001 side on which the thin film transistor is formed of the display device, and FIGS. 15(A)(B) show a structure ( top emission type) in which light emission is extracted from the sealing substrate 1031 side of the display device.

[0326] FIG. 13(A) shows an example of a display device in which optical elements (coloring layers 1034R, coloring layers 1034G, coloring layers 1034B , coloring layer 1034Y) are provided on a transparent base material 1033. Further, FIG. 13 (B) shows an example of a display device in which optical elements (coloring layers 1034R, coloring layers 1034G, coloring layers 1034B) are formed between the gate insulating film 1003 and the first interlayer insulating film 1020. Also, FIG. 14 shows an example of a display device in which optical elements (coloring layers 1034R, coloring layers 1034G, coloring layers 1034B, coloring layer 1034Y) are formed between the first interlayer insulating film 1020 and the second interlayer insulating film 1021.

[0327] The coloring layer 1034R has a function of transmitting red light, the coloring layer 1034G has a function of transmitting green light, and the coloring layer 1034B has a function of transmitting blue light. Also, the coloring layer 1034Y has a function of transmitting yellow light, or a function of transmitting a plurality of lights selected from blue, green, yellow, and red. When the coloring layer 1034Y transmits a plurality of lights selected from blue, green, yellow, and red, When having the function to be performed, the light transmitted through the coloring layer 1034Y may be white. Even if it is yellow Since a light-emitting element that exhibits yellow or white light emission has high luminous efficiency, a display device having the coloring layer 1034Y can reduce power consumption.

[0328] Also, in the top emission type display device shown in FIG. 15, in a light-emitting element having a lower electrode 1024Y as well, similar to the display device of FIG. 12(A), a configuration having a microcavity structure is preferable between the upper electrode 1026. Further, in the display device of FIG. 15(A) it is possible to perform sealing with a sealing substrate 1031 provided with coloring layers (a red coloring layer 1034R, a green coloring layer 1034G, a blue coloring layer 103 4B, and a yellow coloring layer 1034Y).

[0329] The light emission presented through the microcavity and the yellow coloring layer 1034Y becomes light emission having a light emission spectrum in the yellow region. Since yellow is a color with high visibility, a light-emitting element that exhibits yellow light emission has high luminous efficiency. That is, a display device having the configuration of FIG. 15(A) can reduce power consumption.

[0330] Also, in FIG. 15(A), a configuration in which a plurality of light-emitting elements and coloring layers are provided for each of the plurality of light-emitting elements is illustrated, but it is not limited thereto. For example, as shown in FIG. 15(B) a full-color display may be performed in four colors of red, green, blue, and yellow, or four colors of red, green, blue, and white, by providing a red coloring layer 1034R, a green coloring layer 1034G, and a blue coloring layer 1034B without providing a yellow coloring layer. As shown in FIG. 15(A), when a configuration is adopted in which a light-emitting element and a coloring layer are provided for each of the light-emitting elements, an effect such as suppressing external light reflection can be obtained On the other hand, as shown in FIG. 15(B), a light emitting element and a yellow coloring layer are not provided, and a red coloring layer is not provided. When a colored layer of a color, a green colored layer, and a blue colored layer are provided, the color of the light is yellow or white. Since the energy loss of the light emitted from the light-emitting element is small, power consumption can be reduced. This has a positive effect.

[0331] <Display device configuration example 5> Next, a display device according to another embodiment of the present invention is shown in FIG. 16 is a cross-sectional view taken along dashed lines AB and CD. 9B, the same reference numerals are used for the parts having the same functions as those shown in FIG. 9B, and detailed explanations thereof will be given below. The details are omitted.

[0332] The display device 600 shown in FIG. 16 includes an element substrate 610, a sealing substrate 604, and a sealant 60 The region 607 surrounded by 5 has sealing layers 607a, 607b, and 607c. For example, one or more of the sealing layers 607a, 607b, and 607c may include For example, PVC (polyvinyl chloride) resin, acrylic resin, polyimide resin, etc. epoxy resin, silicone resin, PVB (polyvinyl butyral) resin, or EVA Resins such as ethylene vinyl acetate resins can be used. Silicon oxide nitride, silicon nitride oxide, silicon nitride, aluminum oxide, aluminum nitride Alternatively, an inorganic material such as aluminum may be used. By forming the layer c, deterioration of the light emitting element 618 due to impurities such as water can be suppressed. It is preferable to form the sealing layers 607a, 607b, and 607c. The cooling material 605 does not need to be provided.

[0333] Further, any one or two of the sealing layers 607a, 607b, and 607c may be provided, or four or more sealing layers may be formed. By forming multiple sealing layers, impurities such as water can be effectively prevented from entering from the outside of the display device 600 to the light-emitting element 618 inside the display device, which is preferable. When there are multiple sealing layers, it is a preferable configuration to laminate a resin and an inorganic material.

[0334] <Example Configuration 6 of Display Device> In addition, the display devices shown in Configuration Examples 1 to 4 in this embodiment illustrate configurations having optical elements, but as an aspect of the present invention, an optical element may not be provided.

[0335] The display device shown in FIGS. 17(A) and (B) is a display device with a structure (top emission type) that extracts light on the side of the sealing substrate 1031. FIG. 17(A) shows an example of a display device having light-emitting layers 1028R, 1028G, and 1028B in the EL layer 1028. Further, FIG. 17(B) shows an example of a display device having light-emitting layers 1028R, 1028G, 1028B, and 1028Y in the EL layer 1028. The light-emitting layer 1028R exhibits red light emission, the light-emitting layer 1028G exhibits green light emission, and the light-emitting layer 1028B has a function of exhibiting blue light emission. Further, the light-emitting layer 1028Y has a function of exhibiting yellow light emission or a function of exhibiting a plurality of light emissions selected from blue, green, and red. The light emission exhibited by the light-emitting layer 1028Y may be white. Since a light-emitting element that exhibits yellow or white light emission has high luminous efficiency, a display device having the light-emitting layer 1028Y can reduce power consumption.

[0336] ​​​​​​​​​

[0337] The display device shown in FIGS. 17(A) and 17(B) has an EL layer 10 that exhibits light emission of different colors 28 as sub-pixels, so it is not necessary to provide a coloring layer as an optical element.

[0338] Also, the sealing layer 1029 can be made of, for example, a resin such as a PVC (polyvinyl chloride) - based resin, an acrylic - based resin, a polyimide - based resin, an epoxy - based resin, a silicone - based resin, a PVB (polyvinyl but yral) - based resin, or an EVA (ethylene vinyl acetate) - based resin. Further, inorganic materials such as silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride , aluminum oxide, and aluminum nitride may be used. It is preferable to form the sealing layer 1029 to suppress deterioration of the light - emitting element due to impurities such as water. The sealing layer 1029 may be one or two, or four or more sealing layers

[0339] may be formed. Making the sealing layer multi - layer is preferable because it can effectively prevent impurities such as water from entering the display device from the outside to the inside of the display device. When the sealing layer is multi - layer, it is a preferable configuration to laminate a resin and an inorganic material. Note that the sealing substrate 1031 only needs to have a function of protecting the light - emitting element. Therefore, a flexible substrate or film can be used for the sealing substrate 1031. Note that the configuration shown in this embodiment can be appropriately combined with other embodiments or other configurations in this embodiment.

[0340] Note that the sealing substrate 1031 only needs to have a function of protecting the light - emitting element. Therefore, a flexible substrate or film can be used for the sealing substrate 1031. For this reason, a flexible substrate or film can be used for the sealing substrate 1031.

[0341] Note that the configuration shown in this embodiment can be appropriately combined with other embodiments or other configurations in this embodiment. can be combined as appropriate.

[0342] (Embodiment 5) In this embodiment, a display device having a light-emitting element according to one aspect of the present invention will be described with reference to FIGS. 18 to FIG. 20.

[0343] Note that FIG. 18(A) is a block diagram for explaining a display device according to one aspect of the present invention, and FIG. 1 8(B) is a circuit diagram for explaining a pixel circuit included in the display device according to one aspect of the present invention.

[0344] <Explanation of Display Device> The display device shown in FIG. 18(A) includes a region having pixels of display elements (hereinafter referred to as a pixel portion 802) and a circuit portion disposed outside the pixel portion 802 and having a circuit for driving the pixels ( hereinafter referred to as a driving circuit portion 804), a circuit having an element protection function (hereinafter referred to as a protection circuit 80 6), and a terminal portion 807. Note that the protection circuit 806 may not be provided.

[0345] It is desirable that part or all of the driving circuit portion 804 is formed on the same substrate as the pixel portion 802. This can reduce the number of components and terminals. When part or all of the driving circuit portion 804 is not formed on the same substrate as the pixel portion 802, part or all of the driving circuit portion 804 can be mounted by COG or TAB (Tape Automated B onding).

[0346] The pixel portion 802 has a circuit for driving a plurality of display elements arranged in X rows (X is a natural number of 2 or more) and Y columns (Y is a natural number of 2 or more) ( hereinafter referred to as a pixel circuit 801), and the driving circuit portion 804 includes a circuit that outputs a signal (scanning signal) for selecting a pixel (hereinafter referred to as a scanning line driving circuit 804a), and supplies a signal (data signal) for driving the display element of the pixel. ​​​It has a driving circuit such as a circuit (hereinafter referred to as the signal line driving circuit 804b).

[0347] The scanning line driving circuit 804a includes a shift register or the like. The scanning line driving circuit 804a Receives, via the terminal portion 807, a signal for driving the shift register, and outputs a signal. For example, the scanning line driving circuit 804a receives a start pulse signal, a clock signal, etc., And outputs a pulse signal. The scanning line driving circuit 804a has a function of controlling the potential of a wiring (hereinafter referred to as scanning lines GL_1 to GL_X) to which a scanning signal is applied. Note that a plurality of scanning line driving circuits 804a may be provided, and the plurality of scanning line driving circuits 804a may divide and control the scanning lines GL_1 to GL_X. Or, the scanning line driving circuit 804a has a function of being able to supply an initialization signal. However, it is not limited to this, and the scanning line driving circuit 804a can also supply another signal.

[0348] The signal line driving circuit 804b includes a shift register or the like. The signal line driving circuit 804b Receives, via the terminal portion 807, in addition to a signal for driving the shift register, a signal (image signal) that is the source of the data signal. The signal line driving circuit 804b has a function of generating a data signal to be written into the pixel circuit 801 based on the image signal. Also, the signal line driving circuit 804b Has a function of controlling the output of the data signal according to a pulse signal obtained by inputting a start pulse, a clock signal, etc. Also, the signal line driving circuit 804b has a function of controlling the potential of a wiring (hereinafter referred to as data lines DL_1 to DL_Y) to which the data signal is applied. Or, the signal line driving circuit 804b has a function of being able to supply an initialization signal.​​​​​However, the present invention is not limited to this, and the signal line driver circuit 804b may also supply other signals. It is possible.

[0349] The signal line driver circuit 804b is configured using, for example, a plurality of analog switches. The signal line driver circuit 804b sequentially turns on a plurality of analog switches, The image signal can be time-division-multiplexed and output as a data signal. Also, a shift register, etc. The signal line driver circuit 804b may be formed using the same.

[0350] Each of the plurality of pixel circuits 801 is connected to one of the plurality of scanning lines GL to which a scanning signal is applied. A pulse signal is inputted through the data line DL, and a data signal is given through one of the data lines DL. A data signal is input to each of the pixel circuits 801 via a scanning line driving circuit. 804a controls writing and holding of data of the data signal. For example, The second pixel circuit 801 is connected to a scanning line drive circuit via a scanning line GL_m (m is a natural number equal to or smaller than X). A pulse signal is input from 804a, and the potential of the data line DL_n ( A data signal is input from the signal line driver circuit 804b via a data line driver 804c (n is a natural number equal to or smaller than Y).

[0351] The protection circuit 806 shown in FIG. 18A is, for example, a scanning line driver circuit 804a and a pixel circuit 8 01. Alternatively, the protection circuit 806 is connected to the scanning line GL, which is the wiring between the signal line driver The data line DL is connected between the circuit 804b and the pixel circuit 801. The protection circuit 806 can be connected to a wiring between the scanning line driver circuit 804a and the terminal portion 807. Alternatively, the protection circuit 806 may be a wiring between the signal line driver circuit 804b and the terminal portion 807. It can be connected to a line. Note that the terminal portion 807 refers to a portion where terminals for inputting power supply, control signals, and image signals from an external circuit to the display device are provided.

[0352] When a potential outside a certain range is applied to the wiring to which the protection circuit 806 is connected, the protection circuit 806 is a circuit that makes the wiring and another wiring in a conductive state.

[0353] As shown in FIG. 18(A), by providing protection circuits 80 6 in the pixel portion 802 and the drive circuit portion 804 respectively, the resistance of the display device against overcurrent generated by ESD (Electro Static Discharge: electrostatic discharge) etc. can be enhanced. However, the configuration of the protection circuit 806 is not limited to this. For example, a configuration in which the protection circuit 806 is connected to the scanning line drive circuit 804a, or a configuration in which the protection circuit 806 is connected to the signal line drive circuit 804b can also be adopted. Alternatively, a configuration in which the protection circuit 806 is connected to the terminal portion 807 can also be adopted.

[0354] In FIG. 18(A), an example in which the drive circuit portion 804 is formed by the scanning line drive circuit 804a and the signal line drive circuit 804b is shown, but the configuration is not limited to this. For example, a configuration in which only the scanning line drive circuit 804a is formed and a separately prepared signal line drive circuit is mounted on a substrate (for example, a drive circuit substrate formed of a single crystal semiconductor film or a polycrystalline semiconductor film) can also be adopted.

[0355]

[0356] <Configuration Example of Pixel Circuit> The plurality of pixel circuits 801 shown in FIG. 18(A) can be configured as shown in FIG. 18(B), for example.

[0356] ​The pixel circuit 801 shown in FIG. 18(B) includes transistors 852 and 854, a capacitor element 86 2, and a light-emitting element 872.

[0357] One of the source electrode and the drain electrode of the transistor 852 is electrically connected to a wiring (data line DL_n) to which a data signal is supplied. Further, the gate electrode of the transistor 852 is electrically connected to a wiring (scanning line GL_m) to which a gate signal is supplied. The transistor 852 has a function of controlling the writing of data of the data signal.

[0358] One of the pair of electrodes of the capacitor element 862 is electrically connected to a wiring (hereinafter referred to as a potential supply line VL

[0359] _a) to which a potential is supplied, and the other is electrically connected to the other of the source electrode and the drain electrode of the transistor 852. The capacitor element 862 has a function as a holding capacitor for holding the written data.

[0360] One of the source electrode and the drain electrode of the transistor 854 is electrically connected to the potential supply line VL_a. Further, the gate electrode of the transistor 854 is electrically connected to the other of the source electrode and the drain

[0361] electrode of the transistor 852. One of the anode and the cathode of the light-emitting element 872 is electrically connected to a potential supply line VL_b, and the other is electrically connected to the other of the source electrode and the drain electrode of the transistor 854.

[0362] As the light-emitting element 872, the light-emitting elements shown in Embodiments 1 to 3 can be used. One of the anode and the cathode of the light-emitting element 872 is electrically connected to a potential supply line VL_b, and the other is electrically connected to the other of the source electrode and the drain electrode of the transistor 854.

[0363] As the light-emitting element 872, the light-emitting elements shown in Embodiments 1 to 3 can be used. can be used.

[0364] Note that a high power supply potential VDD is applied to one of the potential supply lines VL_a and VL_b, and a low power supply potential VSS is applied to the other.

[0365] In a display device having the pixel circuit 801 of FIG. 18(B), for example, each row of pixel circuits 801 is sequentially selected by the inspection line drive circuit 804a shown in FIG. 18(A), and the transistor 852 is turned on to write the data of the data signal.

[0366] The pixel circuit 801 into which data has been written enters a holding state when the transistor 852 is turned off. Further, the amount of current flowing between the source electrode and the drain electrode of the transistor 854 is controlled according to the potential of the written data signal, and the light-emitting element 872 emits light with a luminance corresponding to the amount of current flowing. By sequentially performing this for each row, an image can be displayed.

[0367] Further, the pixel circuit may be provided with a function of correcting the influence of variations such as the threshold voltage of the transistor. FIGS. 19(A)(B) and 20(A)(B) show an example of the pixel circuit.

[0368] The pixel circuit shown in FIG. 19(A) includes six transistors (transistors 303_1 to 303_6), a capacitive element 304, and a light-emitting element 305. In addition, in the pixel circuit shown in FIG. 19(A), wirings 301_1 to 301_5 and wirings 302_1 and 302_2 are electrically connected. Note that, for transistors 303_1 to 303_6, for example, P-channel type transistors can be used.

[0369] The pixel circuit shown in FIG. 19(B) is obtained by adding a transistor 303 to the pixel circuit shown in FIG. 19(A). ​​​​​​​​​​​It has a configuration with _7 added. Also, in the pixel circuit shown in Fig. 19(B), wiring 301_6 and wiring 301_7 are electrically connected. Here, wiring 301_5 and wiring 301_6 may be electrically connected to each other. Regarding transistor 303_7 , for example, a P-channel type transistor can be used.

[0370] The pixel circuit shown in Fig. 20(A) has six transistors (transistors 308_1 to 3 08_6), a capacitor element 304, and a light-emitting element 305. Also, in Fig. 20(A) shown, wiring 306_1 to 306_3 and wiring 307_1 to 307_ 3 are electrically connected. Here, wiring 306_1 and wiring 306_3 may be electrically connected to each other. Regarding transistors 308_1 to 308_6, for example, P-channel type transistors can be used.

[0371] The pixel circuit shown in Fig. 20(B) has two transistors (transistors 309_1 and tr ansistor 309_2), two capacitor elements (capacitor element 304_1 and capacitor element 304_ 2), and a light-emitting element 305. Also, in the pixel circuit shown in Fig. 20(B), wiring 3 11_1 to wiring 311_3, wiring 312_1, and wiring 312_2 are electrically connected . Also, by adopting the configuration of the pixel circuit shown in Fig. 20(B), for example, a voltage input-ele ctric current drive method (also called CVCC method) can be achieved. Regarding transistors 3...

Claims

1. A light-emitting layer having a metal complex containing a platinum group element, a first organic compound, and a second organic compound, wherein the LUMO level of the first organic compound is lower than the LUMO level of the second organic compound, the HOMO level of the first organic compound is lower than the HOMO level of the second organic compound, the LUMO level of the metal complex containing a platinum group element is lower than the LUMO level of the first organic compound, the energy difference between the LUMO level and the HOMO level of the metal complex containing a platinum group element is larger than the energy difference between the LUMO level of the first organic compound and the HOMO level of the second organic compound, the first organic compound and the second organic compound are a combination that forms an exciplex, the first organic compound is a heterocyclic compound having any one of a triazine skeleton, a pyrimidine skeleton, a pyridazine skeleton, and a pyridine skeleton, the second organic compound is any one of a carbazole compound, a fluorene compound, a triphenylene compound, and a phenanthrene compound, A light-emitting device.

2. A light-emitting layer having a metal complex containing a platinum group element, a first organic compound, and a second organic compound, wherein the LUMO level of the first organic compound is lower than the LUMO level of the second organic compound, the HOMO level of the first organic compound is lower than the HOMO level of the second organic compound, the LUMO level of the metal complex containing a platinum group element is lower than the LUMO level of the first organic compound, the energy difference between the LUMO level and the HOMO level of the metal complex containing a platinum group element is larger than the energy difference between the LUMO level of the first organic compound and the HOMO level of the second organic compound, the first organic compound and the second organic compound are a combination that forms an exciplex, the first organic compound is any one of an oxadiazole derivative, a triazole derivative, a benzimidazole derivative, a phenanthroline derivative, a pyridine derivative, a bipyridine derivative, a pyrimidine derivative, and a triazine derivative, the second organic compound is any one of a carbazole compound, a fluorene compound, a triphenylene compound, and a phenanthrene compound, A light-emitting device.

3. A light-emitting layer having a metal complex containing a platinum group element, a first organic compound, and a second organic compound, The LUMO level of the first organic compound is lower than the LUMO level of the second organic compound, The HOMO level of the first organic compound is lower than the HOMO level of the second organic compound, The LUMO level of the metal complex having the platinum group element is lower than the LUMO level of the first organic compound, The energy difference between the LUMO level and the HOMO level of the metal complex having the platinum group element is larger than the energy difference between the LUMO level of the first organic compound and the HOMO level of the second organic compound, The first organic compound and the second organic compound are a combination that forms an exciplex, The energy difference between the LUMO level of the metal complex having the platinum group element and the HOMO level of the second organic compound is equal to or greater than the transition energy calculated from the absorption edge in the absorption spectrum of the metal complex having the platinum group element, The first organic compound is a heterocyclic compound having any one of a triazine skeleton, a pyrimidine skeleton, a pyridazine skeleton, and a pyridine skeleton, The second organic compound is any one of a carbazole compound, a fluorene compound, a triphenylene compound, and a phenanthrene compound, Light-emitting element.

4. A light-emitting layer having a metal complex having a platinum group element, a first organic compound, and a second organic compound, The LUMO level of the first organic compound is lower than the LUMO level of the second organic compound, The HOMO level of the first organic compound is lower than the HOMO level of the second organic compound, The LUMO level of the metal complex having the platinum group element is lower than the LUMO level of the first organic compound, The energy difference between the LUMO level and the HOMO level of the metal complex having the platinum group element is larger than the energy difference between the LUMO level of the first organic compound and the HOMO level of the second organic compound, The first organic compound and the second organic compound are a combination that forms an exciplex, The energy difference between the LUMO level of the metal complex having the platinum group element and the HOMO level of the second organic compound is equal to or greater than the transition energy calculated from the absorption edge in the absorption spectrum of the metal complex having the platinum group element, The first organic compound is any one of an oxadiazole derivative, a triazole derivative, a benzimidazole derivative, a phenanthroline derivative, a pyridine derivative, a bipyridine derivative, a pyrimidine derivative, and a triazine derivative, The second organic compound is any one of a carbazole compound, a fluorene compound, a triphenylene compound, and a phenanthrene compound, Light-emitting element.

5. A light-emitting layer having a metal complex having a platinum group element, a first organic compound, and a second organic compound, The LUMO level of the first organic compound is lower than the LUMO level of the second organic compound, The HOMO level of the first organic compound is lower than the HOMO level of the second organic compound, The LUMO level of the metal complex having the platinum group element is lower than the LUMO level of the first organic compound, The energy difference between the LUMO level and the HOMO level of the metal complex having the platinum group element is larger than the energy difference between the LUMO level of the first organic compound and the HOMO level of the second organic compound, The first organic compound and the second organic compound are a combination that forms an exciplex, The energy difference between the LUMO level of the metal complex having the platinum group element and the HOMO level of the second organic compound is equal to or higher than the energy of the light emission exhibited by the metal complex having the platinum group element, The first organic compound is a heterocyclic compound having any one of a triazine skeleton, a pyrimidine skeleton, a pyridazine skeleton, and a pyridine skeleton, The second organic compound is any one of a carbazole compound, a fluorene compound, a triphenylene compound, and a phenanthrene compound, Light-emitting element.

6. A light-emitting layer having a metal complex having a platinum group element, a first organic compound, and a second organic compound, The LUMO level of the first organic compound is lower than the LUMO level of the second organic compound, The HOMO level of the first organic compound is lower than the HOMO level of the second organic compound, The LUMO level of the metal complex having the platinum group element is lower than the LUMO level of the first organic compound, The energy difference between the LUMO level and the HOMO level of the metal complex having the platinum group element is larger than the energy difference between the LUMO level of the first organic compound and the HOMO level of the second organic compound, The first organic compound and the second organic compound form a combination that forms an exciplex. The energy difference between the LUMO level of the metal complex having the platinum group element and the HOMO level of the second organic compound is equal to or greater than the energy of the light emission exhibited by the metal complex having the platinum group element. The first organic compound is any one of an oxadiazole derivative, a triazole derivative, a benzimidazole derivative, a phenanthroline derivative, a pyridine derivative, a bipyridine derivative, a pyrimidine derivative, and a triazine derivative. The second organic compound is any one of a carbazole compound, a fluorene compound, a triphenylene compound, and a phenanthrene compound. Light-emitting element.

7. In any one of Claims 1 to 6, The energy difference between the LUMO level and the HOMO level of the metal complex having the platinum group element is 0.4 eV or more greater than the transition energy calculated from the absorption edge in the absorption spectrum of the metal complex having the platinum group element. Light-emitting element.

8. In any one of Claims 1 to 7, The energy difference between the LUMO level and the HOMO level of the metal complex having the platinum group element is 0.4 eV or more greater than the energy of the light emission exhibited by the metal complex having the platinum group element. Light-emitting element.

9. In any one of Claims 1 to 8, The emission spectrum exhibited by the exciplex has a region overlapping with the absorption band on the longest wavelength side of the absorption spectrum of the metal complex having the platinum group element. Light-emitting element.

10. In any one of Claims 1 to 9, The metal complex having the platinum group element has at least one of ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), and platinum (Pt). Light-emitting element.

11. A light-emitting element according to any one of Claims 1 to 10, And at least one of a color filter, a seal, and a transistor. Display device.

12. A display device according to Claim 11, And at least one of a housing and a touch sensor. Electronic device.

13. A light-emitting element according to any one of Claims 1 to 10, And at least one of a housing and a touch sensor. Lighting device.

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