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

Abstract

To provide a light-emitting element that has high luminous efficiency and drives at low voltage.SOLUTION: A light-emitting element includes a guest material and a host material. The LUMO level of the guest material is lower than the LUMO level of the host material. 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 and the HOMO level of the host material. The guest material has a function of converting the triplet excitation energy into light emission. The energy difference between the LUMO level of the guest material and the HOMO level of the host material is more than or equal to the energy of the light emission from the guest material.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] One embodiment of the present invention is a light-emitting element, or a display device, an electronic device, and a lighting device each having the light-emitting element. Regarding the lighting device.

[0002] Note that one embodiment of the present invention is not limited to the above technical fields. The technical field of one aspect of the present invention relates to an article, a method, or a manufacturing method. is a process, machine, manufacture, or composition of matter. Therefore, the technical field of one embodiment of the present invention disclosed in this specification more specifically relates to Examples of the semiconductor device include a semiconductor device, a display device, a liquid crystal display device, a light-emitting device, a lighting device, a power storage device, a memory device, and the like. Examples include devices, methods for driving them, and methods for manufacturing them. . [Background technology]

[0003] In recent years, electroluminescence (EL) The basic structure of these light-emitting devices is as follows: The device has a structure in which a layer containing a light-emitting material (EL layer) is sandwiched between a pair of electrodes. By applying a voltage across the material, light is emitted from the luminescent material.

[0004] Since the above-mentioned light-emitting element is a self-luminous type, a display device using it has excellent visibility and It has the advantage of not requiring a light source and consuming little power. The display device also has the advantage of having a high response speed.

[0005] A light-emitting element in which an organic material is used as the light-emitting material and an EL layer containing the light-emitting material is provided 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, the injected electrons and holes recombine, causing the light-emitting organic material to enter an excited state, and light can be obtained from the excited light-emitting organic material.

[0006] The types of excited states formed by the organic material include singlet excited states (S * ) and triplet excited states (T ). Luminescence from singlet excited states is called fluorescence, and luminescence from triplet excited states is called phosphorescence. * Also, their statistical generation ratios in a light-emitting device are S * :T * = 1 :3. Therefore, a light-emitting device using a material that emits phosphorescence (phosphorescent material) can achieve 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 triplet excited states into light has been actively carried out (see, for example, Patent Document 1).

[0007] The energy required to excite an 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. The energy difference between the energy required to excite the organic material and the energy of the light emission affects the device characteristics as an increase in the driving voltage in the light-emitting device. Therefore, development is underway on techniques to reduce the driving voltage (see Patent Document 2).

[0008] Among light-emitting devices using phosphorescent materials, especially in light-emitting devices that exhibit blue light emission, since it is difficult to develop stable organic materials having a high triplet excitation energy level, they have not yet been put into practical use. Therefore, there is a demand for the development of phosphorescent light-emitting devices that exhibit high luminous efficiency and excellent reliability.

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, as iridium complexes having high emission energy, iridium complexes having a pyridine skeleton or a nitrogen-containing five-membered heterocyclic skeleton in the ligand are known. 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, iridium complexes having these skeletons in the ligand have high HOMO and LUMO levels, and while hole carriers are easily injected, electron carriers are difficult to inject. Therefore, a higher electron-accepting property The development of iridium complexes having a high skeleton as a ligand is underway.

[0011] On the other hand, an iridium complex having a skeleton with high electron-accepting properties as a ligand has a low HOMO level and LUMO level, and while electron carriers are easily injected, hole carriers are difficult to inject. Therefore, excitation by direct recombination of carriers is difficult, and it may be difficult to efficiently emit light from a light-emitting device.

[0012] Therefore, in one aspect of the present invention, in a light-emitting device having a phosphorescent material, one of the problems is to provide a light-emitting device with high luminous efficiency. Or, in one aspect of the present invention, one of the problems is to provide a light-emitting device with reduced power consumption. Or, in one aspect of the present invention, one of the problems is to provide a highly reliable light-emitting device. Or, in one aspect of the present invention, one of the problems is to provide a novel light-emitting device. Or, in one aspect of the present invention, one of the problems is to provide a novel light-emitting device. Or, in one aspect of the present invention, one of the problems is to provide a novel light-emitting device. Or, in one aspect of the present invention, one of the problems is 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 are obvious from the description in the specification and the like, and it is possible to extract other problems from the description in the specification and the like.

Means for Solving the Problems

[0014] One aspect of the present invention is a light-emitting device having a host material capable of efficiently exciting a phosphorescent material.

[0015] ​​​​Accordingly, one aspect of the present invention is a light-emitting element having a guest material and a host material. The LUMO level of the guest material is lower than the LUMO level of the host material, and 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 and the HOMO level of the host material, and the guest material has a function of being able to convert triplet excitation energy into light emission.

[0016] Another aspect of the present invention is a light-emitting element having a guest material and a host material, wherein the LUMO level of the guest material is lower than the LUMO level of the host material, and the L energy difference between the UMO level and the HOMO level of the guest material is larger than the energy difference between the LUMO level and the HOMO level of the host material, and the guest material has a function of being able to convert triplet excitation energy into light emission, and the energy difference between the LUMO level of the guest material and the HOMO level of the host material is equal to or greater than the transition energy calculated from the absorption edge in the absorption spectrum of the guest material.

[0017] Another aspect of the present invention is a light-emitting element having a guest material and a host material, wherein the LUMO level of the guest material is lower than the LUMO level of the host material, and the L energy difference between the UMO level and the HOMO level of the guest material is larger than the energy difference between the LUMO level and the HOMO level of the host material, and the guest material has a function of being able to convert triplet excitation energy into light emission, and the energy difference between the LUMO level of the guest material and the HOMO level of the host material is equal to or greater than

[0018] In each of the above configurations, the energy difference between the LUMO level and the HOMO level of the guest material is preferably larger than the transition energy calculated from the absorption edge in the absorption spectrum of the guest material by 0.4 eV or more. Also, the energy difference between the LUMO level and the HOMO level of the guest material is preferably larger than the energy of the luminescence exhibited by the guest material by 0.4 eV or more. The difference is preferably larger than the transition energy calculated from the absorption edge in the absorption spectrum of the guest material by 0.4 eV or more. Also, in each of the above configurations, it is preferable that the host material has a function of donating excitation energy to the guest material. Also, the emission spectrum of the luminescence exhibited by the host material preferably has a wavelength region overlapping with the absorption band on the lowest energy side in the absorption spectrum of the guest material. The energy difference between the LUMO level and the HOMO level of the guest material is preferably larger than the energy of the luminescence exhibited by the guest material by 0.4 eV or more. Preferably.

[0019] Also, in each of the above configurations, it is preferable that the host material has a difference between the singlet excitation energy level and the triplet excitation energy level that is greater than 0 eV and less than or equal to 0.2 eV. Also, it is preferable that the host material has a function of exhibiting thermally activated delayed fluorescence at room temperature. 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. Also, it is preferable that the host material has a function of exhibiting thermally activated delayed fluorescence at room temperature.

[0020] Also, in each of the above configurations, it is preferable that the host material has a function of donating excitation energy to the guest material. Also, the emission spectrum of the luminescence exhibited by the host material preferably has a wavelength region overlapping with the absorption band on the lowest energy side in the absorption spectrum of the guest material. The host material preferably has a function of donating excitation energy to the guest material. Also, the emission spectrum of the luminescence exhibited by the host material preferably has a wavelength region overlapping with the absorption band on the lowest energy side in the absorption spectrum of the guest material. The emission spectrum of the luminescence exhibited by the host material preferably has a wavelength region overlapping with the absorption band on the lowest energy side in the absorption spectrum of the guest material. Preferably.

[0021] Also, in each of the above configurations, it is preferable that the guest material contains iridium. Also, it is preferable that the guest material exhibits luminescence. The guest material preferably exhibits luminescence.

[0022] Also, in each of the above configurations, it is preferable that the host material has a function of being able to transport electrons, and the host material has a function of being able to transport holes. Also, it is preferable that the host material has a π-electron-deficient heteroaromatic ring skeleton, and the host material has at least one of a π-electron-excessive heteroaromatic ring skeleton or an aromatic amine skeleton. Also, the π-electron-deficient heteroaromatic ring skeleton preferably has at least one of a diazine skeleton or a triazine skeleton, and the π-electron-excessive heteroaromatic ring skeleton preferably has at least one of a diazine skeleton or a triazine skeleton. The host material preferably has a function of being able to transport electrons, and the host material has a function of being able to transport holes. The host material has a π-electron-deficient heteroaromatic ring skeleton, and the host material has at least one of a π-electron-excessive heteroaromatic ring skeleton or an aromatic amine skeleton. Also, it is preferable that the host material has at least one of a π-electron-excessive heteroaromatic ring skeleton or an aromatic amine skeleton. Also, the π-electron-deficient heteroaromatic ring skeleton preferably has at least one of a diazine skeleton or a triazine skeleton. The π-electron-deficient heteroaromatic ring skeleton preferably has at least one of a diazine skeleton or a triazine skeleton, and the π-electron-excessive heteroaromatic ring skeleton preferably has at least one of a diazine skeleton or a triazine skeleton. The complex aromatic ring skeleton preferably has at least one of an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, a thiophene skeleton, and a pyrrole skeleton.

[0023] In addition, in the light-emitting device described in each of the above configurations, it is preferable that the host material is a compound represented by any one of the following structural formulas (500) to (503). [Chemical formula] Another aspect of the present invention is a compound represented by any one of the following structural formulas (500) to (503). [Chemical formula]

[0024] Another aspect of the present invention is a display device having at least one of the light-emitting device of each of the above configurations and a color filter or a transistor. Another aspect of the present invention is an electronic device having at least one of the display device and a housing or a touch sensor. Also An aspect of the present invention is an illumination device having at least one of the light-emitting device of each of the above configurations and a housing or a touch sensor. Another aspect of the present invention includes not only a light-emitting device having a light-emitting element but also an electronic device having the light-emitting device. Therefore, the light-emitting device in this specification refers to an image display device or a light source (including an illumination device). In addition, a connector, for example, an FPC (Flexible Printed Circuit), a T module to which a TCP (Tape Carrier Package) is attached, a module in which a printed wiring board is provided at the tip of a TCP, or a COG (Chip is attached to the light-emitting element is also included in the scope. Therefore, the light-emitting device in this specification refers to an image display device or a light source (including an illumination device). In addition, a connector, for example, an FPC (Flexible Printed Circuit), a T device refers to an image display device or a light source (including an illumination device). Also, a connector, for example, an FPC (Flexible Printed Circuit), a T CP (Tape Carrier Package) is attached to the light-emitting device, for example, a module to which a TCP (Tape Carrier Package) is attached, a module in which a printed wiring board is provided at the tip of a TCP, or a COG (Chip is attached to the light-emitting element module, or a module in which a printed wiring board is provided at the tip of a TCP, or a COG (Chip A module in which an IC (integrated circuit) is directly mounted by the (On Glass) method is also one aspect of the present invention. This is one aspect.

Advantages of the Invention

[0025] 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.

[0026] 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 clearly 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

[0027]

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[0028] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the above description, and the embodiments and details thereof may be modified without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the embodiments described below. The terms and conditions of the present invention are not to be construed as being limited to the content.

[0029] In addition, the position, size, range, etc. of each component shown in the drawings etc. are not necessarily shown in order to facilitate understanding. It may not represent the actual position, size, range, etc. Therefore, the disclosed invention The position, size, range, etc. are not necessarily limited to those disclosed in the drawings, etc.

[0030] In addition, in this specification, ordinal numbers such as 1st, 2nd, etc. are used for convenience, In some cases, the order of processes or layers may not be indicated. For example, "first" may be replaced with "second" or " can be appropriately replaced with "third" etc. The ordinal numbers used to identify an aspect of the present invention may not match. be.

[0031] In addition, in this specification and the like, when explaining the configuration of the invention using drawings, the same The reference numerals may be commonly used even among different drawings.

[0032] In addition, in this specification and the like, the terms "film" and "layer" are interchangeable. For example, the term "conductive layer" can be changed to the term "conductive film." Alternatively, for example, the term "insulating film" may be changed to "insulating layer" It may be possible to change the term to

[0033] In this specification and the like, the singlet excited state (S * ) is a single atom with excitation energy The S1 level is the lowest singlet excited energy level. The lowest excited energy level is the singlet excited state. (T * ) is a triplet state with excitation energy. The lowest excited energy level of the triplet excited state is In this specification and the like, the singlet excited state and the singlet excited energy are simply referred to as the singlet excited state and the singlet excited energy. Even when written as an energy level, it refers to the lowest singlet excited state and the S1 level. In addition, when written as triplet excited state and triplet excited energy level, However, it may represent the lowest triplet excited state and the T1 level.

[0034] In this specification and the like, the fluorescent material refers to a material that emits light when it relaxes from a singlet excited state to a ground state. On the other hand, phosphorescent materials are materials that emit light in the visible light region from the triplet excited state to the ground state. When the material relaxes to the phosphorus state, it emits light in the visible light region at room temperature. An optical material is one of materials that can convert triplet excitation energy into visible light.

[0035] In addition, the phosphorescent emission energy or triplet excitation energy can be derived from the emission peak (including shoulders) or the rising wavelength on the shortest wavelength side of the phosphorescent emission. Specifically, the phosphorescent emission can be derived from the emission peak (including shoulders) or the rising wavelength on the shortest wavelength side of the phosphorescent emission. In addition, the phosphorescent emission can be observed by performing a time-resolved photoluminescence method in a low-temperature environment (for example, 10K). In addition, the emission energy of thermally activated delayed fluorescence is derived from the emission peak (including shoulders) or the rising wavelength on the shortest wavelength side of the thermally activated delayed fluorescence.

[0036] In this specification and the like, room temperature refers to any temperature between 0°C and 40°C.

[0037] In addition, in this specification and the like, the blue wavelength region refers to a wavelength region of 400 nm or more and less than 500 nm, and blue emission refers to emission having at least one emission spectrum peak in this region. In addition, the green wavelength region refers to a wavelength region of 500 nm or more and less than 580 nm, and green emission refers to emission having at least one emission spectrum peak in this region. In addition, the red wavelength region refers to a wavelength region of 580 nm or more and 680 nm or less, and red emission refers to emission having at least one emission spectrum peak in this region.

[0038] (Embodiment 1) In this embodiment, a light-emitting element according to one aspect of the present invention will be described below with reference to FIGS. 1 to 4.

[0039] <Configuration Example 1 of Light-Emitting Element> First, the configuration of a light-emitting element according to one aspect of the present invention will be described below with reference to FIGS. 1(A) and (B).

[0040] ​​​​​FIG. 1(A) is a schematic cross-sectional view of a light-emitting element 150 according to one embodiment of the present invention.

[0041] The light-emitting element 150 has a pair of electrodes (electrode 101 and electrode 102), and an EL layer 100 provided between the pair of electrodes. The EL layer 100 has at least a light-emitting layer 130. .

[0042] In addition, the EL layer 100 shown in FIG. 1(A) has functional layers such as a hole injection layer 111, a hole transport layer 112, an electron transport layer 118, and an electron injection layer 119 in addition to the light-emitting layer 130.

[0043] In the present embodiment, among the pair of electrodes, electrode 101 is described as the anode and electrode 102 is described as the cathode. However, the configuration of the light-emitting element 150 is not limited to this. That is, electrode 101 may be the cathode, electrode 102 may be the anode, and the stacking order of the layers between the electrodes may be reversed. That is, from the anode side, the hole injection layer 111, the hole transport layer 112, the light-emitting layer 130, the electron transport layer 118, and the electron injection layer 119 may be stacked in this order. .

[0044] The configuration of the EL layer 100 is not limited to the configuration shown in FIG. 1(A), and may be a configuration having at least one selected from the hole injection layer 111, the hole transport layer 112, the electron transport layer 118, and the electron injection layer 119. Alternatively, the EL layer 100 may have a functional layer having a function such as reducing a hole or electron injection barrier, improving hole or electron transportability, reducing hole or electron transportability, or suppressing a quenching phenomenon caused by an electrode. Note that each functional layer may be a single layer or a structure in which a plurality of layers are stacked.

[0045] ​​​​​​​​​​ FIG. 1(B) is a schematic cross-sectional view showing an example of the light-emitting layer 130 shown in FIG. 1(A). FIG. 1( The light-emitting layer 130 shown in B) has a guest material 131 and a host material 132.

[0046] Also, in the light-emitting layer 130, the host material 132 is present in the largest amount by weight, and the guest material 131 is dispersed in the host material 132.

[0047] Also, as the guest material 131, a light-emitting organic material may be used, and the light-emitting organic material preferably has a function capable of converting triplet excitation energy into light emission, and is preferably a material capable of emitting phosphorescence (hereinafter also referred to as a phosphorescent material). In the following description, a configuration using a phosphorescent material as the guest material 131 will be described. Therefore, the guest material 131 may be read as a phosphorescent material.

[0048] <Light-emitting mechanism 1 of the light-emitting element> Next, the light-emitting mechanism of the light-emitting layer 130 will be described below.

[0049] In the light-emitting element 150 according to one aspect of the present invention, by applying a voltage between a pair of electrodes (electrode 101 and electrode 102 ), electrons are injected from the cathode and holes are injected from the anode into the EL layer 100, respectively, and a current flows. Then, the injected electrons and holes recombine, and the guest material 131 in the light-emitting layer 130 included in the EL layer 100 becomes excited, and light emission can be obtained from the excited guest material 131.

[0050] Note that light emission from the guest material 131 can be obtained through the following two processes. ·(α) Direct recombination process ·(β) Energy transfer process

[0051] <<(α) Direct recombination process>> First, the direct recombination process in the guest material 131 will be described. Carriers (electrons and holes) recombine in the guest material 131, forming an excited state of the guest material 131. At this time, the energy required to excite the guest material 131 by the direct recombination process of carriers depends on the energy difference between the lowest unoccupied molecular orbital (also referred to as LUMO) level and the highest occupied molecular orbital (also referred to as HOMO) level of the guest material 131. This energy difference generally corresponds to the energy of the singlet excited state. On the other hand, since the guest material 131 is a phosphorescent material, the energy of the triplet excited state is converted into light emission. Therefore, when there is a large energy difference between the singlet excited state and the triplet excited state formed by the guest material 131, the energy required to excite the guest material 131 is higher than the energy of light emission by an amount corresponding to that energy difference. [[ID=!28]]

[0052] [[ID=!29]] [[ID=!30]]The energy difference between the energy required to excite the guest material 131 and the energy of [[ID=!31]] [[ID=!32]]light emission affects the device characteristics as a difference in driving voltage in the light-emitting [[ID=!33]] [[ID=!34]]device. Therefore, in the (α) direct recombination process, the light emission start voltage of the [[ID=!35]] [[ID=!36]]light-emitting device becomes larger than the voltage corresponding to the energy of light emission [[ID=!37]] [[ID=!38]]in the guest material 131. [[ID=!39]]

[0053] [[ID=!40]] Also, when the guest material 131 has a high light emission energy, the LUMO level of the guest material 131 becomes high, making it difficult for electrons, which are carriers, to be injected into It should be noted that there seem to be some tags marked with "!" in the original text which might be incorrect or need further clarification. I've translated the text as accurately as possible based on the provided rules. In the guest material 131, direct recombination of carriers (electrons and holes) is less likely to occur. Therefore, it is difficult to obtain high luminous efficiency in the light-emitting element.

[0054] ≪(β) Energy transfer process≫ Next, to explain the energy transfer process between the host material 132 and the guest material 131, a schematic diagram explaining the correlation of energy levels is shown in Fig. 2(A). In Fig. 2(A), the notations and symbols are as follows. ·Guest(131): Guest material 131 (phosphorescent material) ·Host(132): Host material 132 ·S G : S1 level of the guest material 131 (phosphorescent material) ·T G : T1 level of the guest material 131 (phosphorescent material) ·S H : S1 level of the host material 132 ·T H : T1 level of the host material 132

[0055] When carriers recombine in the host material 132 and singlet and triplet excited states of the host material 132 are formed, as shown by route E1 and route E2 in Fig. 2(A), both the singlet excitation energy and the triplet excitation energy of the host material 132 transfer from the singlet excitation energy level (S ) and the triplet excitation energy level of the host material 132 to the triplet excitation energy level (T H ) of the guest material 131, and the guest material 131 becomes a triplet excited state. Phosphorescent emission can be obtained from the guest material 131 that has become a triplet excited state. H ) to the triplet excitation energy level (T G ) of the guest material 131, and the guest material 131 becomes a triplet excited state. Phosphorescent emission can be obtained from the triplet excited state guest material 131. From the triplet excited state guest material 131, phosphorescent emission can be obtained.

[0056] Note that the singlet excitation energy level (SH ) and triplet excited energy Gee level (T H ) are the triplet excited energy levels (T G ) End In this way, the singlet excitation energy of the generated host material 132 is preferably and triplet excitation energy relative to the singlet excitation energy level (S H ) and triplet excited energy level (T H ) to the triplet excitation energy of guest material 131 Level (T G ) can efficiently transfer energy to

[0057] In other words, in the light-emitting layer 130, excitation energy from the host material 132 to the guest material 131 is Energy is provided.

[0058] In addition, when the light-emitting layer 130 contains a material other than the host material 132 and the guest material 131, In this case, the light-emitting layer 130 is oriented such that the triplet excited energy level (T H ) It is preferable to have a material with a triplet excitation energy level higher than Therefore, the triplet excitation energy of the host material 132 is less likely to be quenched, and the guest material 132 can be efficiently Energy transfer occurs to the substrate material 131.

[0059] In addition, the singlet excitation energy of the host material 132 is higher than the triplet excitation energy of the guest material 131. Energy level (T G ), the host material 13 In 2, the singlet excited energy level (S H ) and triplet excited energy level (T H )'s It is preferable that the energy difference is small.

[0060] Here, FIG. 2(B) shows the energy band diagrams of the guest material 131 and the host material 132. In FIG. 2(B), Guest(131) represents the guest material 131, Hos t(132) represents the host material 132, and ΔE G represents the energy difference between the LUMO level and the H OMO level of the guest material 131. ΔE H represents the energy difference between the LUMO level and the HOM O level of the host material 132, and ΔE B represents the energy difference between the LUMO level of the guest material 131 and the HOMO level of the host material 132. These are notations and symbols.

[0061] For the guest material 131 to emit light with a short emission wavelength and high emission energy, it is preferable that the energy difference (ΔE G ) between the LUMO level and the HOMO level of the guest material 131 is large. On the other hand, in the light-emitting element 150, 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 excited state formed by the host material 132 is preferably small. Therefore, the energy difference (ΔE H ) between the LUMO level and the HOMO level of the host material 132 is preferably small.

[0062] Note that since the guest material 131 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 131 exhibits light emission with an energy smaller than the energy difference (ΔE ) between the LUMO level and the HOMO level. Here, this guest material G The energy difference (ΔE G ) between the LUMO level and the HOMO level of the guest material 131 is greater than the energy difference (ΔE H ) between the LUMO level and the HOMO level of the host material 13 2, even if the emission energy (abbreviation: ΔE Em ) exhibited by the guest material 131 or the transition energy (abbreviation: ΔE ) calculated from the absorption edge in the absorption spectrum is equal to or abs smaller than ΔE H , the inventors have found that the excitation energy can be transferred from the excited state formed by the host material 132 to the guest material 13 1, and light emission can be obtained from the guest material 131. When ΔE of the guest material 131 is greater than the emission energy (ΔE ) exhibited by the guest material 131 or the transition energy (ΔE G ) calculated from the absorption edge in the absorption spectrum , a large amount of electrical energy corresponding to ΔE Em is required to directly electrically excite the guest material 131, so the driving voltage of the light-emitting device becomes high. However, in one aspect of the present invention, the host material 132 is electrically excited by electrical energy corresponding to ΔE abs (smaller than ΔE G ), and the excited state of the guest material 131 is generated by energy transfer therefrom. Therefore, light emission from the guest G material 131 can be obtained at a low driving voltage and with high efficiency. Therefore, the light-emitting device according to one aspect of the present invention can have a lower light emission start voltage (voltage at which the luminance becomes greater than 1 cd / m ) than the voltage corresponding to the emission energy (ΔE H ) of the light emission exhibited by the guest material. That is, ΔE G is such that the host material 132 is electrically excited by electrical energy corresponding to (smaller than ΔE ), and the excited state of the guest material 131 is generated by energy transfer therefrom. Therefore, light emission from the guest material 131 can be obtained at a low driving voltage and with high efficiency. Therefore, the light-emitting device according to one aspect of the present invention can have a lower light emission start voltage (voltage at which the luminance becomes greater than 1 cd / m ) than the voltage corresponding to the emission energy (ΔE 2 ) of the light emission exhibited by the guest material. That is, ΔE is Em ) can be made smaller than the voltage corresponding to the emission energy (ΔE G ) of the light emission exhibited by the guest material. That is, ΔE G is The emission energy (ΔE Em ) exhibited by the guest material 131 or the transition energy (ΔE ) calculated from the absorption edge in the absorption spectrum is significantly larger (for example, when the guest material is a blue light-emitting material), one aspect of the present invention is particularly beneficial. Note that the emission energy (ΔE abs ) can be derived from the emission peak (including the maximum value or shoulder) or the rising wavelength on the shortest wavelength side of the emission spectrum. In addition, when the guest material 131 contains heavy metals, spin-orbit interaction (the interaction between the spin angular momentum and the orbital angular momentum of electrons) promotes the intersystem crossing between the singlet state and the triplet state. Therefore, the transition between the singlet ground state and the triplet excited state in the guest material 131 may be allowed. That is, the efficiency of emission and the probability of absorption related to the transition between the singlet ground state and the triplet excited state of the guest material 131 can be increased. Therefore, the guest material 131 preferably has a metal element with a large spin-orbit interaction, particularly a noble metal element (ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium ( Os), iridium (Ir), or platinum (Pt)), and having iridium in particular can increase the absorption probability related to the direct transition between the singlet ground state and the triplet excited state, which is preferable. Em ) is preferably low for the guest material 131 to be stable and have high reliability. For this purpose, the heavy metal atoms contained in the guest material 131

[0063] In addition, when the guest material 131 contains heavy metals, spin-orbit interaction (the interaction between the spin angular momentum and the orbital angular momentum of electrons) promotes the intersystem crossing between the singlet state and the triplet state. Therefore, the transition between the singlet ground state and the triplet excited state in the guest material 131 may be allowed. That is, the efficiency of emission and the probability of absorption related to the transition between the singlet ground state and the triplet excited state of the guest material 131 can be increased. Therefore, the guest material 131 preferably has a metal element with a large spin-orbit interaction, particularly a noble metal element (ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium ( Os), iridium (Ir), or platinum (Pt)), and having iridium in particular can increase the absorption probability related to the direct transition between the singlet ground state and the triplet excited state, which is preferable. In addition, when the guest material 131 contains heavy metals, spin-orbit interaction (the interaction between the spin angular momentum and the orbital angular momentum of electrons) promotes the intersystem crossing between the singlet state and the triplet state. Therefore, the transition between the singlet ground state and the triplet excited state in the guest material 131 may be allowed. That is, the efficiency of emission and the probability of absorption related to the transition between the singlet ground state and the triplet excited state of the guest material 131 can be increased. Therefore, the guest material 131 preferably has a metal element with a large spin-orbit interaction, particularly a noble metal element (ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium ( Os), iridium (Ir), or platinum (Pt)), and having iridium in particular can increase the absorption probability related to the direct transition between the singlet ground state and the triplet excited state, which is preferable. In addition, when the guest material 131 contains heavy metals, spin-orbit interaction (the interaction between the spin angular momentum and the orbital angular momentum of electrons) promotes the intersystem crossing between the singlet state and the triplet state. Therefore, the transition between the singlet ground state and the triplet excited state in the guest material 131 may be allowed. That is, the efficiency of emission and the probability of absorption related to the transition between the singlet ground state and the triplet excited state of the guest material 131 can be increased. Therefore, the guest material 131 preferably has a metal element with a large spin-orbit interaction, particularly a noble metal element (ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium ( Os), iridium (Ir), or platinum (Pt)), and having iridium in particular can increase the absorption probability related to the direct transition between the singlet ground state and the triplet excited state, which is preferable. Os), iridium (Ir), or platinum (Pt)), and having iridium in particular can increase the absorption probability related to the direct transition between the singlet ground state and the triplet excited state, which is preferable. Os), iridium (Ir), or platinum (Pt)), and having iridium in particular can increase the absorption probability related to the direct transition between the singlet ground state and the triplet excited state, which is preferable. Os), iridium (Ir), or platinum (Pt)), and having iridium in particular can increase the absorption probability related to the direct transition between the singlet ground state and the triplet excited state, which is preferable. Os), iridium (Ir), or platinum (Pt)), and having iridium in particular can increase the absorption probability related to the direct transition between the singlet ground state and the triplet excited state, which is preferable.

[0064] In addition, for the guest material 131 to be stable and have high reliability, the LUMO level of the guest material 131 is preferably low. For this purpose, the heavy metal atoms contained in the guest material 131 ​As the ligand coordinated thereto, it is also preferable that the ligand has a high electron-accepting property and a low LUMO level.

[0065] The guest material having the structure as described above is likely to have a structure of a molecule with a low LUMO level and easy to accept electrons. When the guest material 131 has a molecular structure that easily accepts electrons, the LUMO level of the guest material 131 may be lower than the LUMO level of the host material 132. Furthermore, when ΔE G is larger than ΔE H , the HOMO level of the guest material 131 becomes lower than the HOMO level of the host material 132. At this time, the energy difference between the HOMO level of the guest material 131 and the HOMO level of the host material 132 is larger than the energy difference between the LUMO level of the guest material 131 and the LUMO level of the host material 132.

[0066] Here, when the LUMO level of the guest material 131 is lower than the LUMO level of the host material 132 and the HOMO level of the guest material 131 is lower than the HOMO level of the host material 132, among the carriers (holes and electrons) injected from the pair of electrodes (electrode 101 and electrode 102), the holes injected from the anode are likely to be injected into the host material 132 in the light-emitting layer 130, and the electrons injected from the cathode are likely to be injected into the guest material 131. Therefore, an exciplex may be formed between the guest material 131 and the host material 132. In particular, as the energy difference (ΔE B ) between the LUMO level of the guest material 131 and the HOMO level of the host material 132 becomes smaller than the energy of the light emission exhibited by the guest material 131 (ΔE Em Em ), the generation of the exciplex formed between the guest material 131 and the host material 132 increases. becomes dominant. In this case, since it becomes difficult to generate an excited state in the guest material 131 alone, the luminous efficiency of the light-emitting element decreases.

[0067] The above reaction can be represented by the following general formula (G11) or (G12).

[0068] H + +G - → (H·G) * (G11) H+G * → (H·G) * (G12)

[0069] General formula (G11) is a reaction in which the host material 132 receives a hole (H + ), and the guest material 131 receives an electron (G - ), thereby generating an exciplex ((H·G) * ). Further, general formula (G12) is a reaction in which the excited guest material 131 (G ) interacts with the ground-state host material 132 (H) * to generate an exciplex ((H·G) ) of the host material 132 and the guest material 131 * . When the host material 132 and the guest material 131 form an exciplex ((H·G) ), it becomes difficult to generate the excited state (G * ) of the guest material 131 alone. The exciplex formed by the host material 132 and the guest material 131 has an excitation energy approximately corresponding to the energy difference (ΔE * ) between the LUMO level of the guest material 131 and the HOMO level of the host material 132. However, the LUM of the guest material 131

[0070] O level and the HOMO level of the host material 132. UMO level and the HOMO level of the host material 132. B ) approximately corresponds to the excitation energy of the exciplex. However, the LUM of the guest material 131 The energy difference (ΔE B ) between the O level and the HOMO level of the host material 132 is greater than or equal to the energy (ΔE Em ) of the emission exhibited by the guest material 131 or the transition energy (ΔE abs ) calculated from the absorption edge in the absorption spectrum. When this is the case, the reaction of forming an exciplex between the host material 132 and the guest material 131 can be suppressed, and the inventors have found that efficient emission can be obtained from the guest material 131. At this time, since ΔE abs is smaller than ΔE B , the guest material 131 easily receives excitation energy, and it is more energetically favorable and stable for the guest material 131 to receive the excitation energy and enter the excited state than to form an exciplex with the host material 132. As described above, the energy difference (ΔE

[0071] ) between the LUMO level and the HOMO level of the guest material 131 is greater than the energy difference ( ΔE G ) between the LUMO level and the HOMO level of the host material 132. Even in this case, if the transition energy (ΔE ΔE H ) calculated from the absorption edge in the absorption spectrum of the guest material 131 is equal to or smaller than ΔE abs ) is equal to or smaller than ΔE H , efficient excitation energy transfer occurs from the excited host material 132 to the guest material 131 . As a result, one of the features of one aspect of the present invention is that a light-emitting device with low voltage and high efficiency can be obtained . At this time, ΔE >ΔE G ≧ΔE H ≧ΔE abs (ΔE G is larger than ΔE H , and ΔE H is ΔE abs ​is as described above. Therefore, when the energy difference (ΔE ) between the LUMO level and the HOM G O level of the guest material 131 is larger than the transition energy (ΔE ) calculated from the absorption edge in the absorption spectrum of the guest material 131, the mechanism of one aspect of the present invention is suitable. More specifically, the energy difference (ΔE abs ) between the LUMO level and the HOMO level of the guest material 131 is preferably 0.3 eV or more, more preferably 0 .4 eV or more larger than the transition energy (ΔE ) calculated from the absorption edge in the absorption spectrum of the guest material 131. Further, since the energy of the light emission exhibited by the guest material 131 (ΔE G ) is equal to or smaller than ΔE , the energy difference (ΔE abs ) between the LUMO level and the HOMO level of the guest material 131 is preferably 0.3 eV or more, more preferably 0.4 eV or more larger than the energy of the light emission (ΔE ) exhibited by the guest material 131. (ΔE Em ) is, ΔE abs and is equal to or smaller than it. Therefore, the energy difference (ΔE ) between the LUMO level and the HOMO level of the guest material 131 is preferably 0.3 eV or more, more preferably 0.4 eV or more larger than the energy of the light emission (ΔE G ) exhibited by the guest material 131. (ΔE Em ) of the guest material 131. More preferably.

[0072] Furthermore, when the LUMO level of the guest material 131 is lower than the LUMO level of the host material 132, as described above, ΔE ≧ΔE B (ΔE abs is ΔE B or more), or ΔE abs B ≧ΔE Em (ΔE B is ΔE Em or more) is preferable. Therefore, ΔE G >ΔE H >ΔE B ≧ΔE abs (ΔE G is ΔE H ​Larger than ΔE H is ΔE B Larger than ΔE B is ΔE abs or more), or ΔE G > ΔE H > ΔE B ≧ ΔE Em (ΔE G is ΔE H than larger, ΔE H is ΔE B Larger than ΔE B is ΔE Em or more) is preferable. These conditions are also an important discovery in one aspect of the present invention.

[0073] Also, the energy difference (ΔE H ) between the LUMO level and the HOMO level of the host material 132 is , equivalent to or slightly larger than the singlet excitation energy level (S H ) of the host material 132. Also, the ho st material 132's singlet excitation energy level (S H ) is larger than the triplet excitation energy level (T H ). Also, the triplet excitation energy level (T H ) of the host material 132 is larger than that of the guest material 131's triplet excitation energy level (T G ). Therefore, ΔE G > ΔE H ≧ S H > T H ≧ T G (ΔE G is ΔE H larger than, ΔE H is S H or more, and S H is T H larger than, T H is T G or more) is obtained. In addition, in the absorption spectrum of the guest material 131 The absorption related to the absorption end is between the singlet ground state and the triplet excited state of the guest material 131 When it is the absorption related to the transition, ΔT G becomes an energy equivalent to or slightly smaller than ΔE abs . Therefore, for ΔE G to be at least 0.3 eV or more larger than ΔE abs , the energy difference between S G and ΔE abs is preferably smaller than the energy difference between S H and T H . Specifically, the energy difference between S and T H is preferably larger than 0 eV and 0.2 H eV or less, more preferably larger than 0 eV and 0.1 eV or less.

[0074] Since the energy difference between the singlet excitation energy level and the triplet excitation energy level is small, as a material suitable for the host material 132 , a thermally activated delayed fluorescence (TADF) material can be mentioned . The thermally activated delayed fluorescence material has a function of converting the triplet excitation energy into the singlet excitation energy by reverse intersystem crossing because the energy difference between the singlet excitation energy level and the triplet excitation energy level is small. Note that as the host material 132 according to one aspect of the present invention . does not necessarily need to have a high reverse intersystem crossing efficiency from T to S , and since it does not necessarily need to have a high photon yield from S H to S H , it is possible to widely select materials. H

[0075] Also, the energy difference between the singlet excitation energy level and the triplet excitation energy level is made small In order to achieve this, the host material 132 preferably has a skeleton having a function of transporting holes (hole transporting property) and a skeleton having a function of transporting electrons (electron transporting property). In this case, since the excited state of the host material 132 has a HOMO molecular orbital in the skeleton having hole transporting property and a LUMO molecular orbital in the skeleton having electron transporting property, the overlap between the HOMO molecular orbital and the LUMO molecular orbital becomes extremely small. That is, it becomes easy to form a donor-acceptor type excited state within a single molecule, and the energy difference between the singlet excited energy level and the triplet excited energy level becomes small. In the host material 132, the difference between the singlet excited energy level (S H ) and the triplet excited energy level (T H ) is preferably H greater than 0 eV and 0.2 eV or less.

[0076] The molecular orbital represents the spatial distribution of electrons in a molecule and can represent the probability of finding electrons. The electron configuration (spatial distribution and energy of electrons) of a molecule can be described in detail by the molecular orbital.

[0077] When the host material 132 has a skeleton with strong donor properties, holes injected into the light-emitting layer 130 are easily injected into and transported by the host material 132. When the host material 132 has a skeleton with strong acceptor properties, electrons injected into the light-emitting layer 130 are easily injected into and transported by the host material 132. By doing so, it becomes easy to form an excited state in the host material 132, which is preferable.

[0078] Note that the emission wavelength of the guest material 131 becomes shorter and the emission energy (ΔE Em ) becomes large ​​​​​As it increases, the energy difference (ΔE G ) between the LUMO level and the HOMO level of the guest material 131 becomes larger. Accordingly, a large amount of energy is required to directly electrically excite the guest material. However, in one aspect of the present invention, if the transition energy (ΔE ) calculated from the absorption edge in the absorption spectrum of the guest material 131 is equal to or smaller than ΔE , the guest material 131 can be excited with energy on the order of ΔE abs , which is lower in energy than ΔE H . Therefore, the power consumption of the light-emitting device can be reduced. Thus, the larger the energy difference between the transition energy (ΔE ) calculated from the absorption edge in the absorption spectrum of the guest material 131 and the energy difference (ΔE G ) between the LUMO level and the HOMO level of the guest material 131 (that is, particularly in the case of a guest material exhibiting blue emission), the more remarkable the effect of the light-emitting mechanism of one aspect of the present invention becomes. H However, when the transition energy (ΔE ) calculated from the absorption edge in the absorption spectrum of the guest material 131 becomes small, the energy (ΔE ) of the light emission exhibited by the guest material 131 also becomes small, making it difficult to obtain light emission having high energy such as blue light emission. That is, if the difference between ΔE and ΔE abs becomes too large, it becomes difficult to obtain light emission having high energy such as blue light emission. From these considerations, the energy difference between the LUMO level and the HOMO level of the guest material 131 G and the energy difference between the transition energy (ΔE ) and the energy difference (ΔE

[0079] ) between the LUMO level and the HOMO level of the guest material 131 (ΔE ) calculated from the absorption edge in the absorption spectrum of the guest material 131 are larger (that is, particularly in the case of a guest material exhibiting blue emission), the more remarkable the effect of the light-emitting mechanism of one aspect of the present invention becomes. abs However, when the transition energy (ΔE Em ) calculated from the absorption edge in the absorption spectrum of the guest material 131 becomes small, the energy (ΔE ) of the light emission exhibited by the guest material 131 also becomes small, making it difficult to obtain light emission having high energy such as blue light emission. That is, if the difference between ΔE abs and ΔE G becomes too large, it becomes difficult to obtain light emission having high energy such as blue light emission. From these facts, the energy difference between the LUMO level and the HOMO level of the guest material 131

[0080] Therefore, the energy difference between the LUMO level and the HOMO level of the guest material 131 (ΔE G ) is the transition energy calculated from the absorption edge in the absorption spectrum of the guest material 131. The energy (ΔE abs ) is preferably larger in the range of 0.3 eV or more and 0.8 eV or less, more preferably larger in the range of 0.4 eV or more and 0.8 eV or less, and even more preferably larger in the range of 0.5 eV or more and 0.8 eV or less. Also, the energy (ΔE ) of the light emission exhibited by the guest material 131 is Em equal to or smaller than ΔE abs . Therefore, the energy difference (ΔE ) between the LUMO level and the HOMO level of the guest material 131 is G larger than the energy (ΔE ) of the light emission exhibited by the guest material 131 in the range of 0.3 eV or more and 0.8 eV or less, Em preferably larger, more preferably larger in the range of 0.4 eV or more and 0.8 eV or less, and even more preferably larger in the range of 0.5 eV or more and 0.8 eV or less. Moreover, since the LUMO level of the guest material 131 is lower than the LUMO level of the host material 132,

[0081] the guest material 131 functions as an electron trap in the light-emitting layer 130. When the guest material 131 functions as an electron trap, it becomes possible to easily control the carrier balance in the light-emitting layer, and the effect of extending the lifetime can be obtained, which is preferable. On the other hand, if the LUMO level of the guest material 131 is too low, the above-mentioned ΔE will become small. Therefore, the energy difference between the LUMO level of the guest material 131 and the LUMO level of the host material 132 is preferably 0.05 eV or more and 0.4 eV or less. Also, the energy difference between the HO B MO level of the guest material 131 and the HOMO level of the host material 132 is preferably 0.05 eV or more. Moreover, the energy difference between the LUMO level of the guest material 131 and the LUMO level of the host material 132 is preferably 0.05 eV or more and 0.4 eV or less. Also, the energy difference between the HOMO level of the guest material 131 and the HOMO level of the host material 132 is preferably 0.05 eV or more. It is above eV, more preferably above 0.1 eV, and even more preferably above 0.2 eV. By doing so, hole carriers are easily injected into the host material 132, which is preferable. Also, since the energy difference (ΔE ) between the LUMO level and the HOMO level of the host material 132 is smaller than the energy difference (ΔE

[0082] ) between the LUMO level and the HOMO level of the guest material 131, as the excited state formed by the recombination of carriers (holes and electrons) injected into the light-emitting layer 130, the excited state formed by the host material 132 is energetically more stable. H ) is Therefore, most of the excited states generated by the direct recombination of carriers in the light-emitting layer 130 will exist as the excited state formed by the host material 132. Thus, according to the configuration of one aspect of the present invention, by facilitating the transfer of excitation energy from the host material 132 to the guest material 131, the driving voltage of the light-emitting element can be reduced, and the light-emitting G ) is smaller, so as the excited state formed by the recombination of carriers (holes and electrons) injected into the light-emitting layer 130, the excited state formed by the host material 132 is energetically more stable. efficiency can be increased. Moreover, from the relationship between the LUMO level and the HOMO level described above, it is preferable that the reduction potential of the guest material 131 is higher than the reduction potential of the host material 132. The oxidation potential and the reduction Therefore, most of the excited states generated by the direct recombination of carriers in the light-emitting layer 130 will exist as the excited state formed by the host material 132. Thus, according to the configuration of one aspect of the present invention, by facilitating the transfer of excitation energy from the host material 132 to the guest material 131, the driving voltage of the light-emitting element can be reduced, and the light-emitting efficiency can be increased. Also, by configuring the light-emitting layer 130 as described above, light emission from the guest material 131 of the light-emitting layer 130 can be efficiently obtained. efficiency can be increased.

[0083] potential can be measured by cyclic voltammetry (CV). potential is preferably higher than the reduction potential of the host material 132. Regarding the oxidation potential and the reduction potential, they can be measured by cyclic voltammetry (CV).

[0084] By configuring the light-emitting layer 130 as described above, light emission from the guest material 131 of the light-emitting layer 130 can be efficiently obtained.

[0085] <Energy Transfer Mechanism> Next, the domination of the energy transfer process between the host material 132 and the guest material 131 will be described. The factors will be explained. As mechanisms of intermolecular energy transfer, two mechanisms, the Förster mechanism (dipole-dipole interaction) and the Dexter mechanism (electron exchange interaction), have been proposed.

[0086] ≪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 132 and the guest material 131. Due to the resonance phenomenon of dipole vibrations, the host material 132 transfers energy to the guest material 131, the excited host material 132 returns to the ground state, and the ground state guest material 131 becomes excited. The rate constant k of the Förster mechanism is shown in Equation (1). h*→g

[0087]

Equation

[0088] In Equation (1), ν represents the frequency, f’(ν) represents the normalized emission spectrum of the host material 132 (fluorescence spectrum when discussing energy transfer from the singlet excited state, phosphorescence spectrum when discussing energy transfer from the triplet excited state), h ε(ν) represents the molar extinction coefficient of the guest material 131, N represents Avogadro's number, n represents the refractive index of the medium, R represents the intermolecular distance between the host material 132 and the guest material 131, τ represents the measured lifetime of the excited state (fluorescence lifetime or phosphorescence lifetime), and c represents the speed of light. ε g , φ represents the luminescence quantum yield (fluorescence quantum yield when discussing energy transfer from the singlet excited state, and phosphorescence quantum yield when discussing energy transfer from the triplet excited state), and K is 2 a coefficient (ranging from 0 to 4) representing the orientation of the transition dipole moments of the host material 132 and the guest material 131. In the case of random orientation, K = 2 / 3. Note that in the case of random orientation, K 2 = 2 / 3.

[0089] ≪Dexter mechanism≫ In the Dexter mechanism, the host material 132 and the guest material 131 approach the contact effective distance where orbital overlap occurs, and energy transfer occurs through the exchange of electrons between the excited-state electrons of the host material 132 and the ground-state electrons of the guest material 13 1. Note that the rate constant k of the Dexter mechanism is shown in Equation (2). h*→g In Equation (2), h is the Planck constant, K is a constant with the dimension of energy, ν represents the frequency, f’

[0090]

Equation

[0091] (ν) represents the normalized emission spectrum of the host material 132 (fluorescence spectrum when discussing energy transfer from the singlet excited state, and phosphorescence spectrum when discussing energy transfer from the triplet excited state), ε’ is h (ν) represents the normalized absorption spectrum of the guest material 131, L represents the effective molecular radius, and R represents the intermolecular distance between the host material 132 and the guest material 131. g (ν) is a coefficient (ranging from 0 to 4) representing the orientation of the transition dipole moments of the host material 132 and the guest material 131. Here, the energy transfer efficiency φ from the host material 132 to the guest material 131 is

[0092] Here, the energy transfer efficiency φ ET from the host material 132 to the guest material 131 is It is represented by formula (3). k r is the rate constant of the luminescence process of the host material 132 (fluorescence when discussing energy transfer from the singlet excited state, phosphorescence when discussing energy transfer from the triplet excited state). ), and k is the rate constant of the non-luminescence process (thermal deactivation or intersystem crossing) of the host material 132, and τ represents the measured lifetime of the excited state of the host material 132. n is the rate constant of the non-luminescence process (thermal deactivation or intersystem crossing) of the host material 132, and τ represents the measured lifetime of the excited state of the host material 132. From formula (3), it can be seen that in order to increase the energy transfer efficiency φ

[0093]

Equation

[0094] From the mathematical formula (3), to increase the energy transfer efficiency φ ET it is necessary to increase the rate constant k of energy transfer and make the other competing rate constant k h*→g +k r +k n (=1 / τ) relatively smaller.

[0095] ≪Concept for enhancing energy transfer≫ In the energy transfer by the Förster mechanism, the energy transfer efficiency φ ET should be higher when the luminescence quantum yield φ (fluorescence quantum yield when discussing energy transfer from the singlet excited state, phosphorescence quantum yield when discussing energy transfer from the triplet excited state) is higher. Also, it is preferable that the overlap between the emission spectrum of the host material 132 (fluorescence spectrum when discussing energy transfer from the singlet excited state) and the absorption spectrum of the guest material 131 (absorption corresponding to the transition from the singlet ground state to the triplet excited state) is large. Furthermore, it is preferable that the molar absorption coefficient of the guest material 131 is also high. This means that the emission of the host material 132 ), and it is preferable that the overlap between the emission spectrum of the host material 132 (fluorescence spectrum when discussing energy transfer from the singlet excited state) and the absorption spectrum of the guest material 131 (absorption corresponding to the transition from the singlet ground state to the triplet excited state) is large. Furthermore, it is preferable that the molar absorption coefficient of the guest material 131 is also high. This means that the emission of the host material 132 ), and it is preferable that the overlap between the emission spectrum of the host material 132 (fluorescence spectrum when discussing energy transfer from the singlet excited state) and the absorption spectrum of the guest material 131 (absorption corresponding to the transition from the singlet ground state to the triplet excited state) is large. Furthermore, it is preferable that the molar absorption coefficient of the guest material 131 is also high. This means that the emission of the host material 132 ), and it is preferable that the overlap between the emission spectrum of the host material 132 (fluorescence spectrum when discussing energy transfer from the singlet excited state) and the absorption spectrum of the guest material 131 (absorption corresponding to the transition from the singlet ground state to the triplet excited state) is large. Furthermore, it is preferable that the molar absorption coefficient of the guest material 131 is also high. This means that the emission of the host material 132 ), and it is preferable that the overlap between the emission spectrum of the host material 132 (fluorescence spectrum when discussing energy transfer from the singlet excited state) and the absorption spectrum of the guest material 131 (absorption corresponding to the transition from the singlet ground state to the triplet excited state) is large. Furthermore, it is preferable that the molar absorption coefficient of the guest material 131 is also high. This means that the emission of the host material 132 ), and it is preferable that the overlap between the emission spectrum of the host material 132 (fluorescence spectrum when discussing energy transfer from the singlet excited state) and the absorption spectrum of the guest material 131 (absorption corresponding to the transition from the singlet ground state to the triplet excited state) is large. Furthermore, it is preferable that the molar absorption coefficient of the guest material 131 is also high. This means that the emission of the host material 132 It means that the spectrum overlaps with the absorption band that appears on the longest wavelength side of the guest material 131. .

[0096] Also, in energy transfer by the Dexter mechanism, to increase the rate constant k h*→g . it is preferable that the overlap between the emission spectrum of the host material 132 (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 131 (absorption corresponding to the transition from the singlet ground state to the triplet excited state) is large. Therefore, optimization of the energy transfer efficiency is achieved by the overlap between the emission spectrum of the host material 132 and the absorption band that appears on the longest wavelength side of the guest material 131. . . . . .

[0097] <Configuration Example 2 of Light-Emitting Element> Next, a light-emitting element having a configuration different from the configuration shown in FIGS. 1(A) and 1(B) will be described below with reference to FIGS. 3(A) and 3(B).

[0098] FIG. 3(A) is a cross-sectional schematic view of a light-emitting element 152 according to one embodiment of the present invention. In FIG. 3(A), portions having the same functions as those denoted by the same reference numerals in FIG. 1(A) may be denoted by the same hatching 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. . . .

[0099] The light-emitting element 152 has a pair of electrodes (electrode 101 and electrode 102), and has an EL layer 100 provided between the pair of electrodes. The EL layer 100 has at least a light-emitting layer 135. . .

[0100] FIG. 3(B) is a schematic cross-sectional view showing an example of the light-emitting layer 135 shown in FIG. 3(A). FIG. 3( The light-emitting layer 135 shown in B) has at least a guest material 131, a host material 132, and a phos phor material 133.

[0101] Also, in the light-emitting layer 135, the host material 132 or the host material 133 is present in the largest amount by weight, and the guest material 131 is dispersed in the host material 132 and the host material 133.

[0102] <Light-emitting mechanism 2 of the light-emitting element> Next, the light-emitting mechanism of the light-emitting layer 135 will be described below.

[0103] Also in the light-emitting element 152 according to one aspect of the present invention, holes and electrons injected from a pair of electrodes (electrode 101 and electrode 102 ) recombine, so that the guest material 131 in the light-emitting layer 135 included in the EL layer 100 is excited, and light can be obtained from the excited guest material 131.

[0104] Note that light emission from the guest material 131 can be obtained through the following two processes. · (α) Direct recombination process · (β) Energy transfer process

[0105] Note that the (α) direct recombination process is the same as the direct recombination process described in the light-emitting mechanism of the above light-emitting layer 130, so the description here is omitted.

[0106] ≪(β) Energy transfer process≫ To explain the energy transfer process among the host material 132, the host material 133, and the guest material 131, a schematic diagram for explaining the correlation of energy levels is shown in FIG. 4(A). Note that FIG. The notations and symbols in 4(A) are as follows. For other notations and symbols, refer to FIG 2(A). ·Host(133): Host material 133 ·S A : S1 level of host material 133 ·T A : T1 level of host material 133

[0107] When carriers recombine in host material 132 and singlet and triplet excited states of host material 132 are formed, as shown in routes E1 and E2 in FIG. 4(A), both the singlet excitation energy and the triplet excitation energy of host material 132 move from the singlet excitation energy level (S ) and the triplet excitation energy level ( ) of host material 132 to the triplet excitation energy level (T H ) of guest material 131, and guest material T H ) to the triplet excitation energy level (T G ) of guest material 131, and guest material 131 becomes a triplet excited state. Phosphorescent emission can be obtained from triplet excited state guest material 131.

[0108] In addition, in order to efficiently transfer the excitation energy from host material 132 to guest material 131 , it is preferable that the triplet excitation energy level (T A ) of host material 133 is higher than the triplet excitation energy level (T ) of host material 132 H ). This makes it less likely for quenching of the triplet excitation energy of host material 132 to occur, and energy transfer to guest material 13 1 occurs efficiently.

[0109] Also, as shown in the energy band diagram in FIG. 4(B), when the LUMO level of guest material 131 is lower than the LUMO level of host material 132, as described in the light emission mechanism 1 of the previous light emitting element ​ As mentioned above, the energy difference (ΔE G ) is the energy difference (ΔE H ) greater than The larger the ΔE H is the LUMO level of the guest material 131 and the LUMO level of the host material 132. Energy difference with the HOMO level (ΔE B ) is preferable.

[0110] The HOMO level of the host material 133 is lower than the HOMO level of the host material 132. and the LUMO level of the host material 133 is higher than the LUMO level of the guest material 131. That is, the energy between the LUMO level and the HOMO level of the host material 133 is preferably The energy difference is the energy between the LUMO level of the guest material 131 and the HOMO level of the host material 132. Energy difference (ΔE B ) is larger than the host material 133 and the host material 13 2 to form an exciplex, and the host material 133 and the guest material 131 to form an exciplex. In FIG. 4(B), the reaction of forming Host (13 3) represents the host material 133, and other notations and symbols are the same as those in FIG. 2(B).

[0111] The difference between the HOMO level of the host material 133 and the HOMO level of the host material 132, and The difference between the LUMO level of the host material 133 and the LUMO level of the guest material 131 is The energy is preferably 0.1 eV or more, and more preferably 0.2 eV or more. By having an energy difference, the electrons injected from the pair of electrodes (electrode 101 and electrode 102) Electron and hole carriers are transported through the guest material 131 and the host material 132, respectively. It is suitable because it is likely to be injected into

[0112] In addition, the HOMO level of the host material 133 may be higher or lower than the HOMO level of the guest material 131. The LUMO level of the host material 133 may be higher or lower than the LUMO level of the host material 132. It is preferably higher than the LUMO level of the host material 132.

[0113] Also, the energy difference between the LUMO level and the HOMO level of the host material 133 is preferably larger than the energy difference (ΔE ) between the LUMO level and the HOMO level of the host material 132. H At this time, the energy difference (ΔE ) between the LUMO level and the HOMO level of the host material 132 is smaller than the energy difference (ΔE H ) between the LUMO level and the HOMO level of the guest material 131. Therefore, as the excited state formed by the recombination of carriers (holes and electrons) injected into the light-emitting layer 135, it is more energetically stable for the host material 132 to form an excited state than for the host material 133 and the guest material 131 to form excited states alone. G Therefore, most of the excited states generated by the direct recombination of carriers in the light-emitting layer 135 will exist as the excited state formed by the host material 132. Therefore, also in the light-emitting layer 135, similar to the structure of the light-emitting layer 130 described above, by facilitating the transfer of excitation energy from the excited state of the host material 132 to the guest material 131, the driving voltage of the light-emitting element 152 can be reduced, and the luminous efficiency can be increased. In addition, in the host material 133, holes and electrons recombine and the host material 133 is excited It is more stable for the host material 132 to form an excited state than for the host material 133 and the guest material 131 to form excited states alone. Therefore, most of the excited states generated by the direct recombination of carriers in the light-emitting layer 135 will exist as the excited state formed by the host material 132. Therefore, also in the light-emitting layer 135, similar to the structure of the light-emitting layer 130 described above, by facilitating the transfer of excitation energy from the excited state of the host material 132 to the guest material 131, the driving voltage of the light-emitting element 152 can be reduced, and the luminous efficiency can be increased. By making it easier for the excitation energy to move from the excited state of the host material 132 to the guest material 131, the driving voltage of the light-emitting element 152 can be reduced, and the luminous efficiency can be increased.

[0114] Also, in the host material 133, holes and electrons recombine and the host material 133 is excited Even when forming the starting state, the energy difference between the LUMO level and the HOMO level of the host material 133 is greater than the energy difference between the LUMO level and the HOMO level of the host material 132, the excitation energy of the host material 133 can quickly transfer energy to the host material 132. Thereafter, the excitation energy undergoes a process similar to the light-emitting mechanism of the above-described light-emitting layer 130, and transfers energy to the guest material 131, so that light emission from the guest material 131 can be obtained. Considering that holes and electrons can recombine in the host material 133 as well, it is preferable that the host material 133 is also a material with a small energy difference between the singlet excitation energy level and the triplet excitation energy level, similar to the host material 132, and particularly preferably a thermally activated delayed fluorescence material.

[0115] In order to efficiently obtain light emission from the guest material 131, the singlet excitation energy level (S ) of the host material 133 is preferably equal to or higher than the singlet excitation energy level (S A ) of the host material 132, H and the triplet excitation energy level (T ) of the host material 133 is preferably equal to or higher than the triplet excitation energy level (T A ) of the host material 132. H

[0116]

[0117] Furthermore, from the relationship between the LUMO level and the HOMO level described above, the oxidation potential of the host material 133 is preferably higher than the oxidation potential of the host material 132, and the reduction potential of the host material 133 is preferably lower than the reduction potential of the guest material 131.

[0117] In addition, the combination of the host material 132 and the host material 133 has a function of transporting holes. When it is a combination of a material having a function of transporting electrons and a material having a function of transporting electrons, the mixing ratio Thus, it becomes possible to easily control the carrier balance. Specifically, a material having a function of transporting holes : a material having a function of transporting electrons = 1:9 to 9:1 (weight ratio) The range is preferable. Further, by having this configuration, it is possible to easily control the carrier balance Therefore, the control of the carrier recombination region can also be easily performed.

[0118] By making the light-emitting layer 135 have the above-described configuration, light emission from the guest material 131 of the light-emitting layer 135 can be efficiently obtained.

[0119] <Material> Next, the details of the components of the light-emitting device according to one aspect of the present invention will be described below.

[0120] ≪Light-emitting layer≫ In the light-emitting layer 130 and the light-emitting layer 135, the host material 132 is present in a weight ratio at least more than that of the guest material 1 31, and the guest material 131 (phosphorescent material) is dispersed in the host material 132.

[0121] ≪Host material 132≫ It is preferable that the energy difference between the S1 level and the T1 level of the host material 132 is small, and specifically, it is more than 0 eV and 0.2 eV or less.

[0122] The host material 132 preferably has a skeleton having hole-transporting properties and a skeleton having electron-transporting properties. Alternatively, the host material 132 preferably has a π-electron-excessive type heteroaromatic ring skeleton or an aromatic amine skeleton and a π-electron-deficient type heteroaromatic ring skeleton. By doing so, it becomes easy to form a donor-acceptor type excited state in the molecule. Further, the host ​​It is preferable that the host material 132 has a structure in which a skeleton having electron transporting properties and a skeleton having hole transporting properties are directly bonded so that both the donor property and the acceptor property are enhanced within the molecule. Alternatively, it is preferable to have a structure in which a π-electron rich heteroaromatic ring skeleton or an aromatic amine skeleton and a π-electron deficient heteroaromatic ring skeleton are directly bonded. By enhancing both the donor property and the acceptor property within the molecule, the overlap between the region where the molecular orbitals in the HOMO of the host material 132 are distributed and the region where the molecular orbitals in the LUMO are distributed can be reduced. This can reduce the energy difference between the singlet excitation energy level and the triplet excitation energy level of the host material 132. In addition, it becomes possible to keep the triplet excitation energy level of the host material 132 at a high energy. Examples of materials with a small energy difference between the singlet excitation energy level and the triplet excitation energy level include thermally activated delayed fluorescence materials. Since thermally activated delayed fluorescence materials have a small difference between the triplet excitation energy level and the singlet excitation energy level, they have a function of converting energy from the triplet excited state to the singlet excited state by reverse intersystem crossing. 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 excitation energy level and the singlet 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.

[0123] [[ID=Challenge 26]]

[0124] When the thermally activated delayed fluorescence material is composed of one type of material, for example, the following materials can be used can be used.

[0125] First, fullerenes and their derivatives, acridine derivatives such as proflavine, and eosin etc. can be mentioned. Also, metal-containing porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (S n), 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 (Sn F2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF2(OEP)), etioporphyrin-tin fluoride complex (SnF2(E tio I)), octaethylporphyrin-platinum chloride complex (PtCl2OEP) etc. can be mentioned.

[0126]

Chemical formula

[0127] Also, as the thermally activated delayed fluorescence material composed of one type of material, heterocyclic compounds having a π-electron excess type heteroaromatic ring and a π-electron deficient type 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-carbazol yl-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PC CzPTzn), 2-[4-(10H-phenoxazin-10-yl)phenyl]-4, 6-diphenyl-1,3,5-triazine (abbreviation: PXZ-TRZ), 3-[4-(5- phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl yl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl- 9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN) , bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), 10-phenyl-10H,10’H-spiro[acridine -9,9’-anthracene]-10’-one (abbreviation: ACRSA), etc. are mentioned. The complex ring compound has a π-electron excess type heteroaromatic ring and a π-electron deficient type heteroaromatic ring, so it has high electron transport property and hole transport property, which is preferable. Among them, among the skeletons having a π-electron deficient type heteroaromatic ring , the diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), and tri azine skeleton are preferable because they are stable and have good reliability. Also, among the skeletons having a π-electron excess type heteroaromatic ring , the acridine skeleton, phenoxazine skeleton, phenothiazine skeleton, furan skeleton, thiophene skeleton, and pyrrole skeleton are stable and have good reliability, so it is preferable to have at least one of these skeletons. In addition, as the furan skeleton, the dibenzofuran skeleton is preferable, and as the thiophene skeleton, the dibenzothiophene skeleton is preferable. Also, as the pyrrole skeleton, the indole skeleton, carbazole skeleton, and 9-phenyl-3,3’-bi- The 9H-carbazole skeleton is particularly preferred. Note that for a substance in which a π-electron-excessive heteroaromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded, the donor property of the π-electron-excessive heteroaromatic ring and the π-electron deficiency of the acceptor property of the heteroaromatic ring are both strong, and the difference in the energy levels of the singlet excited state and the triplet excited state is small, which is particularly preferred. Note that instead of the π-electron-deficient heteroaromatic ring, an aromatic ring bonded with an electron-withdrawing group such as a cyano group may be used.

[0128]

Chemical formula

[0129] Further, as the skeleton having a π-electron-deficient heteroaromatic ring, a condensed hetero ring skeleton having a diazine skeleton is preferred because it is more stable and has good reliability. Among them, a benzofuropyrimidine skeleton and a benzothienopyrimidine skeleton are particularly preferred because of their high acceptor property. Examples of the benzofuropyrimidine skeleton include a benzofuro[3,2-d]pyrimidine skeleton. Examples of the benzothienopyrimidine skeleton include a benzothieno[3,2-d]pyrimidine skeleton.

[0130] As the skeleton having a π-electron-excessive heteroaromatic ring, a bicarbasole skeleton is preferred because of its high excitation energy, stability, and good reliability. Examples of the bicarbasole skeleton include a bicarbasole skeleton in which two carbazolyl groups are bonded to each other at any one of the 2 to 4 positions. The bicarbasole skeleton is particularly preferred because of its high donor property. Examples of the bicarbasole skeleton include 2,2’-bi-9H-carbazole skeleton, 3,3’-bi-9H-carbazole skeleton, 4,4 ,2’-bi-9H-carbazole skeleton, 3,3’-bi-9H-carbazole skeleton, 4,4 ​​​​​’-Bi-9H-carbazole skeleton, 2,3’-Bi-9H-carbazole skeleton, 2,4’- Bi-9H-carbazole skeleton, 3,4’-Bi-9H-carbazole skeleton, etc. can be mentioned. .

[0131] In addition, from the viewpoint of making the band gap wider and the triplet excitation energy higher, a compound in which the 9-position of one of the carbazolyl groups in the bicarbazole skeleton is directly bonded to a benzofuropyrimidine skeleton or a benzothienopyrimidine skeleton is preferable. Further, when the bicarbazole skeleton and the benzofuropyrimidine skeleton or the benzothienopyrimidine skeleton are directly bonded, a compound with a relatively low molecular weight is obtained, so it has a structure suitable for vacuum evaporation (it can be vacuum-evaporated at a relatively low temperature) and is preferable. Generally, when the molecular weight is low, the heat resistance after film formation is often low. However, since the benzofuropyrimidine skeleton, the benzothienopyrimidine skeleton, and the bicarbazole skeleton are rigid skeletons, a compound having such a skeleton can have sufficient heat resistance even if the molecular weight is relatively low. In addition, since the said structure increases the band gap and raises the excitation energy level, it is preferable.

[0132] In addition, in the case where the bicarbazole skeleton and the benzofuropyrimidine skeleton or the benzothienopyrimidine skeleton are bonded via an arylene group, and when the number of carbon atoms of the arylene group is 6 to 25, preferably 6 to 13, not only can both the band gap and the triplet excitation energy be kept high, but also a compound with a relatively low molecular weight is obtained, so it has a structure suitable for vacuum evaporation (it can be vacuum-evaporated at a relatively low temperature).

[0133] Further, the bicarbazole skeleton is directly or via an arylene group, benzofuro[3,2 -d]pyrimidine skeleton or benzothieno[3,2-d]pyrimidine skeleton, more preferably, by bonding to the 4-position of the benzofuro[3,2-d]pyrimidine skeleton or benzothieno[3,2- d]pyrimidine skeleton, the carrier transport property of the compound becomes excellent transport property. Therefore, the light-emitting device using the compound can be driven at a low voltage .

[0134] ≪Example 1 of compound≫ A compound suitable for the light-emitting device of one embodiment of the present invention shown above is a compound represented by the following general formula (G0).

[0135]

Chemical formula

[0136] In the above general formula (G0), A represents a substituted or unsubstituted benzofuropyrimidine skeleton , or a benzothienopyrimidine skeleton. When the benzofuropyrimidine skeleton or benz zothienopyrimidine skeleton has a substituent, examples of the substituent include an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 13 carbon atoms can also be selected as the substituent. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, an n-hexyl group, and the like. Further, specific examples of the cycloalkyl group having 3 to 7 carbon atoms include a cyclopropyl group, a cyclobut yl group, a cyclopentyl group, a cyclohexyl group, and the like. Further, the number of carbon atoms ​​Examples of the aryl group having 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, etc. can be cited as specific examples.

[0137] Also, R 1 to R 15 each independently represents hydrogen, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 13 carbon atoms. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, an n-hexyl group, etc. can be cited. Specific examples of the cycloalkyl group having 3 to 7 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc. Also, specific examples of the aryl group having 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, etc. Further, the above-mentioned alkyl group, cycloalkyl group, and aryl group may have a substituent, and the substituents may be bonded to each other to form a ring. The substituents include an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, or an aryl group having 6 to 13 carbon atoms, which can also be selected as substituents. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, an n-hexyl group, etc. Also, specific examples of the cycloalkyl group having 3 to 7 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc. can be selected as substituents. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, an n-hexyl group, etc. propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, an n-hexyl group, etc. Specific examples of the cycloalkyl group having 3 to 7 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc. can be specifically cited. Examples thereof include. Further, examples of the aryl group having 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, etc. can be specifically cited as examples.

[0138] Also, Ar 1 represents an arylene group having 6 to 25 carbon atoms or a single bond, and the arylene group may have a substituent, and the substituents may be bonded to each other to form a ring. Such an example is, for example, when the 9-position carbon of the fluorenyl group has two phenyl groups as substituents, and the phenyl groups are bonded to each other to form a spirofluorene skeleton. Examples of the arylene group having 6 to 25 carbon atoms include a phenylene group, a naphthylene group, a biphenyldiyl group, a fluorenediyl group, etc. can be specifically cited as examples. When the arylene group has a substituent, examples of the substituent include an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, or an aryl group having 6 to 13 carbon atoms can also be selected as a substituent. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, an n-hexyl group, etc. Also, specific examples of the cycloalkyl group having 3 to 7 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc. Also, examples of the aryl group having 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, etc. can be specifically cited as examples. Examples thereof include.

[0139] Further, in the compound represented by the general formula (G0), the benzofuropyrimidine skeleton is a benzo Preferably, it is a zofuro[3,2-d]pyrimidine skeleton. Also, benzothienopyrimidine The skeleton is preferably a benzothieno[3,2-d]pyrimidine skeleton.

[0140] Also, in the compound represented by the general formula (G0), at the 9-position of one carbazolyl group of the bicarbazole skeleton, directly or via an arylene group, it is bonded to the 4-position of a benzofuro[3,2-d] pyrimidine skeleton or a benzothieno[3,2-d]pyrimidine skeleton, and the compound having the structure has both strong donor properties and acceptor properties and has a wide band gap Therefore, it is particularly preferably used for a light-emitting element that exhibits high-energy light emission such as blue light. The above compound is a compound represented by the following general formula (G1). It is a preferably configuration. The above compound is a compound represented by the following general formula (G1).

[0141]

Chemical formula

[0142] In the above general formula (G1), Q represents oxygen or sulfur.

[0143] Also, R 1 to R 20 each independently represents hydrogen, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 13 carbon atoms. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, an n-hexyl group, and the like. Also, specific examples of the cycloalkyl group having 3 to 7 carbon atoms include a cyclopropyl group, a cyclo propyl group, a cyclohexyl group, etc. Also, specific examples of the aryl group having 6 to 13 carbon atoms include a phenyl group, a naphthyl group, etc. ​Examples of the alkyl group include a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. Examples of the aryl group having 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, a fluoro group, and the like. Specific examples include the alkyl group and cyclohexane group. The alkyl group and the aryl group may have a substituent, and the substituents are bonded to each other. The substituent may be an alkyl group having 1 to 6 carbon atoms, a group having 3 or more carbon atoms, or a group having 4 or more carbon atoms. A cycloalkyl group having from 1 to 7 carbon atoms or an aryl group having from 6 to 13 carbon atoms may also be selected as a substituent. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, Propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, n-hexyl group Examples of the cycloalkyl group having 3 to 7 carbon atoms include a cycloalkyl group and a cycloalkyl group. Specifically, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, etc. Examples of the aryl group having 6 to 13 carbon atoms include a phenyl group, Specific examples include a naphthyl group, a biphenyl group, and a fluorenyl group.

[0144] Also, Ar 1 represents an arylene group having 6 to 25 carbon atoms or a single bond, The alkyl group may have a substituent, and the substituents may be bonded to each other to form a ring. An example of such a compound is a compound in which the carbon atom at the 9th position of the fluorenyl group has a phenyl group as a substituent. The two phenyl groups bond together to form a spirofluorene skeleton. Examples of the arylene group having 6 to 25 carbon atoms include a phenylene group, Specific examples include naphthylene group, biphenyldiyl group, and fluorenediyl group. In addition, when the arylene group has a substituent, the substituent may be a group having a carbon number of an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, or a An aryl group can also be selected as a substituent. Examples of alkyl groups having 1 to 6 carbon atoms include Specifically, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group groups, tert-butyl groups, n-hexyl groups, etc. Specific examples of the cycloalkyl group of the seventh to seventh series include a cyclopropyl group, a cyclobutyl group, a cyclobutyl group, a cyclopropyl ... and cyclopentyl and cyclohexyl groups. The aryl group includes a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, etc. can be cited as an example.

[0145] In the compound represented by general formula (G1), the bicarbazole skeleton is 3,3'- It is a bi-9H-carbazole skeleton, and one of the carbazolyl groups of the bicarbazole skeleton is At the 9-position, a benzofuro[3,2-d]pyrimidine skeleton is attached directly or via an arylene group. Compounds with a structure bonded to the 4-position of the benzothieno[3,2-d]pyrimidine skeleton Since the material has excellent carrier transport properties, light-emitting devices using it can be driven at low voltage. This is a preferred configuration. The compound is a compound represented by the following general formula (G2).

[0146] [ka]

[0147] In the above general formula (G2), Q represents oxygen or sulfur.

[0148] Also, R 1 ~R20 is, independently of each other, hydrogen, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 13 carbon atoms. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, an n-hexyl group, and the like. Specific examples of the cycloalkyl group having 3 to 7 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and the like. Further, specific examples of the aryl group having 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, and the like. Furthermore, the above-described alkyl group, cycloalkyl group, and aryl group may have a substituent, and the substituents may be bonded to each other to form a ring. Examples of the substituent include an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, or an aryl group having 6 to 13 carbon atoms. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, an n-hexyl group, and the like. Specific examples of the cycloalkyl group having 3 to 7 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and the like. Specific examples of the aryl group having 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, and the like. Specific examples of the cycloalkyl group having 3 to 7 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group and the like. Specific examples of the aryl group having 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, and the like.

[0149] Also, Ar 1represents an arylene group having 6 to 25 carbon atoms or a single bond, and the arylene group may have a substituent, and the substituents may be bonded to each other to form a ring. As an example of this, for example, the 9-position carbon of the fluorenyl group has two phenyl groups as substituents, and when the phenyl groups are bonded to each other, a spirofluorene skeleton is formed. Examples of the arylene group having 6 to 13 carbon atoms include a phenylene group, a naphthylene group, a biphenyldiyl group, a fluorenediyl group, etc. can be specifically cited as examples. When the arylene group has a substituent, examples of the substituent include an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, or an aryl group having 6 to 13 carbon atoms can also be selected as the substituent. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, an n-hexyl group, etc. can be cited. Specific examples of the cycloalkyl group having 3 to 7 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc. can be cited. Specific examples of the aryl group having 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, etc. can

[0150] be specifically cited as examples. In the compound represented by the general formula (G1) or (G2), when the bicarbazole skeleton and the benzofuropyrimidine skeleton or the benzothienopyrimidine skeleton are directly bonded, the band gap is improved, and it is possible to synthesize with high purity, so it is a preferable The light-emitting element can be driven at a low voltage.

[0151] In the general formula (G1) or (G2), R 1 to R 14 , and R 16 to R 20 are all hydrogen, which is advantageous in terms of ease of synthesis and raw material price. Furthermore , since it becomes a compound with a relatively low molecular weight, it has a structure suitable for vacuum deposition, which is particularly preferable. The compound is a compound represented by the following general formula (G3) or general formula (G4).

[0152]

Chemical formula

[0153] In the general formula (G3), Q represents oxygen or sulfur.

[0154] Also, R 15 is hydrogen, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 13 carbon atoms. Specific examples of the alkyl group having 1 to 6 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, te rt-butyl group, n-hexyl group, etc. can be mentioned. Also, as the cycloalkyl group having 3 to 7 carbon atoms, specific examples include cyclopropyl group, cyclobutyl group, cyclopent yl group, cyclohexyl group, etc. can be mentioned. Also, as the aryl group having 6 to 13 carbon atoms, phenyl group, naphthyl group, biphenyl group, fluorenyl group, etc. can be mentioned as specific examples. Furthermore, the above-mentioned alkyl group, cycloalkyl group, and aryl group The Ru group may have a substituent, and the substituents may be bonded to each other to form a ring. Examples of the substituent include an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, or an aryl group having 6 to 13 carbon atoms can also be selected as the substituent. Specifically, the alkyl group having 1 to 6 carbon atoms includes, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, an n-hexyl group, and the like. Specific examples of the cycloalkyl group having 3 to 7 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and the like. Specific examples of the aryl group having 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, and the like.

[0155] Also, Ar 1 represents an arylene group having 6 to 25 carbon atoms or a single bond, and the arylene group may have a substituent, and the substituents may be bonded to each other to form a ring. Examples of this include, for example, a case where the 9-position carbon of a fluorenyl group has two phenyl groups as substituents, and the phenyl groups are bonded to each other to form a spirofluorene skeleton. Specific examples of the arylene group having 6 to 25 carbon atoms include a phenylene group, a naphthylene group, a biphenyldiyl group, a fluorenediyl group, and the like. When the arylene group has a substituent, examples of the substituent include an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, or an aryl group having 6 to 13 carbon atoms can also be selected as the substituent. Specifically, the alkyl group having 1 to 6 carbon atoms Specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, an n-hexyl group, etc. can be mentioned. Further, as the cycloalkyl group having 3 to 7 carbon atoms, specifically, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc. can be mentioned. Further, as the aryl group having 6 to 13 carbon atoms, a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, etc. can be specifically mentioned as examples.

[0156]

Chemical formula

[0157] In the general formula (G4) above, Q represents oxygen or sulfur.

[0158] Also, R 15 represents any one of hydrogen, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 13 carbon atoms. Specifically, as the alkyl group having 1 to 6 carbon atoms, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, tert- butyl group, an n-hexyl group, etc. can be mentioned. Further, as the cycloalkyl group having 3 to 7 carbon atoms, specifically, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc. can be mentioned. Further, as the aryl group having 6 to 13 carbon atoms, a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, etc. can be specifically mentioned as examples. Furthermore, the above-mentioned alkyl group, cycloalkyl group, and aryl The Ru group may have a substituent, and the substituents may be bonded to each other to form a ring. When As the substituent, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, or an aryl group having 6 to 13 carbon atoms can also be selected as the substituent. As for the alkyl group having 1 to 6 carbon atoms, specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, an n-hexyl group, etc. can be mentioned. Also, as the cycloalkyl group having 3 to 7 carbon atoms, specifically, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc. can be mentioned. Also, as the aryl group having 6 to 13 carbon atoms, a phenyl group, a naphthyl group, a biphenyl group and a fluorenyl group can be mentioned as specific examples.

[0159] Also, Ar 1 represents an arylene group having 6 to 25 carbon atoms or a single bond, and the arylene group may have a substituent, and the substituents may be bonded to each other to form a ring. As such an example, for example, the 9-position carbon of the fluorenyl group has two phenyl groups as substituents, and when the phenyl groups are bonded to each other, a spirofluorene skeleton is formed such a case can be mentioned. As the arylene group having 6 to 25 carbon atoms, a phenylene group, a naphthylene group, a biphenyldiyl group, a fluorenediyl group, etc. can be mentioned as specific examples. When the arylene group has a substituent, as the substituent, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, or an aryl group having 6 to 13 carbon atoms can also be selected as the substituent. As for the alkyl group having 1 to 6 carbon atoms Specifically, examples include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, an n-hexyl group, and the like. Further, specific examples of the cycloalkyl group having 3 to 7 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and the like. Further, specific examples of the aryl group having 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, and the like. In the general formula (G0), as the benzofuropyrimidine skeleton or benzothienopyrimidine skeleton represented by A, for

[0160] example, the structures represented by the following structural formulas (Ht-1) to (Ht-24) can be applied. Note that the structures that can be used as A are not limited to these. In the above structural formulas (Ht-1) to (Ht-24), R to R

[0161]

Chemical formula

[0162]

Chemical formula

[0163] to R 16 to R 20 each independently represent hydrogen, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 13 carbon atoms. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, and the like. Examples include an alkyl group, an n-hexyl group, etc. Further, examples of the cycloalkyl group having 3 to 7 carbon atoms include, specifically, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc. Examples of the aryl group having 6 to 13 carbon atoms include, as specific examples, a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, etc. Furthermore, the above-described alkyl group, cycloalkyl group, and aryl group may have a substituent, and the substituents may be bonded to each other to form a ring. Examples of the substituent include an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, or an aryl group having 6 to 13 carbon atoms, which can also be selected as a substituent. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, an n-hexyl group, etc. Examples of the cycloalkyl group having 3 to 7 carbon atoms include, specifically, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc. Examples of the aryl group having 6 to 13 carbon atoms include, as specific examples, a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, etc. In addition, in the general formulas (G0) and (G1), examples of the structure that can be used as the bicarba zol skeleton include, for example, the structures represented by the following structural formulas (Cz-1) to (Cz-9). Note that the structures that can be used as the bicarba zol skeleton are not limited to these.

[0164] In addition, in the general formulas (G0) and (G1), examples of the structure that can be used as the bicarba zol skeleton include, for example, the structures represented by the following structural formulas (Cz-1) to (Cz-9). Note that the structures that can be used as the bicarba zol skeleton are not limited to these.

[0165] [Chemical formula]

[0166]

Chem.

[0167] In the above structural formulas (Cz-1) to (Cz-9), R 1 to R 15 are each independently hydrogen, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 13 carbon atoms. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group and an n-hexyl group. Specific examples of the cycloalkyl group having 3 to 7 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclo hexyl group. Specific examples of the aryl group having 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group and the like. Further, the above-mentioned alkyl group, cycloalkyl group, and aryl group may have a substituent, and the substituents may be bonded to each other to form a ring. The substituent is an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, or an aryl group having 6 to 13 carbon atoms, which can also be selected as a substituent. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, and an n-hexyl group. Specific examples of the cycloalkyl group having 3 to 7 carbon atoms include a cyclopropyl group, a cyclobutyl and the like. Further, the above-mentioned alkyl group, cycloalkyl group, and aryl group may have a substituent, and the substituents may be bonded to each other to form a ring. The substituent is an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, or an aryl group having 6 to 13 carbon atoms, which can also be selected as a substituent. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, and an n-hexyl group. Further, the above-mentioned alkyl group, cycloalkyl group, and aryl group may have a substituent, and the substituents may be bonded to each other to form a ring. The substituent is an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, or an aryl group having 6 to 13 carbon atoms, which can also be selected as a substituent. Specific examples of the cycloalkyl group having 3 to 7 carbon atoms include a cyclopropyl group, a cyclobutyl Examples include an alkyl group, a cyclopentyl group, a cyclohexyl group, etc. Further, the aryl group having 6 to 13 carbon atoms includes, as specific examples, a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, etc.

[0168] Further, in the general formulas (G0) to (G4), the arylene group represented by Ar 1 can be, for example, a group represented by the following structural formulas (Ar-1) to (Ar-27). Note that the group that can be used as Ar is not limited to these and may have a substituent. 1

[0169]

Chemical formula

[0170]

Chemical formula

[0171] Further, R in the general formulas (G1) and (G2) 1 to R 20 , R in the general formula (G0) 1 to R 15 , and R in the general formulas (G3) and (G4) 15 , which represent an alkyl group, a cycloalkyl group, or an aryl group, can be, for example, a group represented by the following structural formulas (R-1) to (R-29). Note that the group that can be used as an alkyl group, a cycloalkyl group, or an aryl group is not limited to these and may have a substituent.

[0172]

Chemical formula

[0173] ≪Specific Examples of Compounds≫ Specific structures of the compounds represented by the general formulas (G0) to (G4) include the following compounds represented by structural formulas (100) to (147). Note that the compounds represented by the general formulas (G 0) to (G4) are not limited to the following examples.

[0174]

Chem.

[0175]

Chem.

[0176]

Chem.

[0177]

Chem.

[0178]

Chem.

[0179]

Chem.

[0180]

Chem.

[0181]

Chem.

[0182] ≪Example 2 of Compounds≫ Note that the host material 132 only needs to have a small energy difference between the singlet excited energy level and the triplet excited energy level, and does not necessarily need to have a high intersystem crossing efficiency. It does not need to have a high photoluminescence quantum yield, nor does it need to have a function of exhibiting thermally activated delayed fluorescence. In that case, the host material 132 preferably has a structure in which at least one of a skeleton having a π-electron-excessive heteroaromatic ring or an aromatic amine skeleton and a skeleton having a π-electron-deficient heteroaromatic ring are bonded through a structure having at least one of an m-phenylene group or an o-phenylene group. Alternatively, it is preferably bonded through a biphenyldiyl group. Alternatively, it preferably has a structure bonded through an arylene group having at least one of an m-phenylene group or an o-phenylene group, and the arylene group is more preferably a biphenyldiyl group. By doing so, the T1 level of the host material 132 can be increased. Note that even in this case, the skeleton having a π-electron-deficient heteroaromatic ring preferably has at least one of a diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton) and a triazine skeleton. The skeleton having a π-electron-excessive heteroaromatic ring preferably has at least one of an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, a thiophene skeleton, and a pyrrole skeleton. As the furan skeleton, a dibenzofuran skeleton is preferable, and as the thiophene skeleton, a dibenzothiophene skeleton is preferable. As the pyrrole skeleton, an indole skeleton, a carbazole skeleton, and a 9-phenyl-3,3'-bi-9H-carbazole skeleton are particularly preferable. As the aromatic amine skeleton, a so-called tertiary amine having no NH bond is preferable, and a triarylamine is particularly preferable. It does not need to have a high photoluminescence quantum yield, nor does it need to have a function of exhibiting thermally activated delayed fluorescence. In that case, the host material 132 preferably has a structure in which at least one of a skeleton having a π-electron-excessive heteroaromatic ring or an aromatic amine skeleton and a skeleton having a π-electron-deficient heteroaromatic ring are bonded through a structure having at least one of an m-phenylene group or an o-phenylene group. Alternatively, it is preferably bonded through a biphenyldiyl group. Alternatively, it preferably has a structure bonded through an arylene group having at least one of an m-phenylene group or an o-phenylene group, and the arylene group is more preferably a biphenyldiyl group. By doing so, the T1 level of the host material 132 can be increased. Note that even in this case, the skeleton having a π-electron-deficient heteroaromatic ring preferably has at least one of a diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton) and a triazine skeleton. The skeleton having a π-electron-excessive heteroaromatic ring preferably has at least one of an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, a thiophene skeleton, and a pyrrole skeleton. As the furan skeleton, a dibenzofuran skeleton is preferable, and as the thiophene skeleton, a dibenzothiophene skeleton is preferable. As the pyrrole skeleton, an indole skeleton, a carbazole skeleton, and a 9-phenyl-3,3'-bi-9H-carbazole skeleton are particularly preferable. As the aromatic amine skeleton, a so-called tertiary amine having no NH bond is preferable, and a triarylamine is particularly preferable. Note that even in this case, the skeleton having a π-electron-deficient heteroaromatic ring preferably has at least one of a diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton) and a triazine skeleton. The skeleton having a π-electron-excessive heteroaromatic ring preferably has at least one of an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, a thiophene skeleton, and a pyrrole skeleton. As the furan skeleton, a dibenzofuran skeleton is preferable, and as the thiophene skeleton, a dibenzothiophene skeleton is preferable. As the pyrrole skeleton, an indole skeleton, a carbazole skeleton, and a 9-phenyl-3,3'-bi-9H-carbazole skeleton are particularly preferable. As the aromatic amine skeleton, a so-called tertiary amine having no NH bond is preferable, and a triarylamine is particularly preferable. Note that even in this case, the skeleton having a π-electron-deficient heteroaromatic ring preferably has at least one of a diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton) and a triazine skeleton. The skeleton having a π-electron-excessive heteroaromatic ring preferably has at least one of an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, a thiophene skeleton, and a pyrrole skeleton. As the furan skeleton, a dibenzofuran skeleton is preferable, and as the thiophene skeleton, a dibenzothiophene skeleton is preferable. As the pyrrole skeleton, an indole skeleton, a carbazole skeleton, and a 9-phenyl-3,3'-bi-9H-carbazole skeleton are particularly preferable. As the aromatic amine skeleton, a so-called tertiary amine having no NH bond is preferable, and a triarylamine is particularly preferable. Note that even in this case, the skeleton having a π-electron-deficient heteroaromatic ring preferably has at least one of a diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton) and a triazine skeleton. The skeleton having a π-electron-excessive heteroaromatic ring preferably has at least one of an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, a thiophene skeleton, and a pyrrole skeleton. As the furan skeleton, a dibenzofuran skeleton is preferable, and as the thiophene skeleton, a dibenzothiophene skeleton is preferable. As the pyrrole skeleton, an indole skeleton, a carbazole skeleton, and a 9-phenyl-3,3'-bi-9H-carbazole skeleton are particularly preferable. As the aromatic amine skeleton, a so-called tertiary amine having no NH bond is preferable, and a triarylamine is particularly preferable. Note that as the furan skeleton, a dibenzofuran skeleton is preferable, and as the thiophene skeleton, a dibenzothiophene skeleton is preferable. As the pyrrole skeleton, an indole skeleton, a carbazole skeleton, and a 9-phenyl-3,3'-bi-9H-carbazole skeleton are particularly preferable. As the aromatic amine skeleton, a so-called tertiary amine having no NH bond is preferable, and a triarylamine is particularly preferable. Note that as the furan skeleton, a dibenzofuran skeleton is preferable, and as the thiophene skeleton, a dibenzothiophene skeleton is preferable. As the pyrrole skeleton, an indole skeleton, a carbazole skeleton, and a 9-phenyl-3,3'-bi-9H-carbazole skeleton are particularly preferable. As the aromatic amine skeleton, a so-called tertiary amine having no NH bond is preferable, and a triarylamine is particularly preferable. Note that as the furan skeleton, a dibenzofuran skeleton is preferable, and as the thiophene skeleton, a dibenzothiophene skeleton is preferable. As the pyrrole skeleton, an indole skeleton, a carbazole skeleton, and a 9-phenyl-3,3'-bi-9H-carbazole skeleton are particularly preferable. As the aromatic amine skeleton, a so-called tertiary amine having no NH bond is preferable, and a triarylamine is particularly preferable. A skeleton is preferred. As the aryl group of the triarylamine skeleton, a substituted or unsubstituted aryl group having 6 to 13 carbon atoms forming a ring is preferred, and examples thereof include a phenyl group, a naphthyl group, a fluorenyl group and the like.

[0183] Examples of the above-mentioned aromatic amine skeleton and the skeleton having a π-electron-excessive heteroaromatic ring include skeletons represented by the following general formulas (401) to (417). In the general formulas (413) to (416), X represents an oxygen atom or a sulfur atom.

[0184]

Chemical formula

[0185] In addition, examples of the skeleton having the above-mentioned π-electron-deficient heteroaromatic ring include skeletons represented by the following general formulas (20 1) to (218).

[0186]

Chemical formula

[0187] When a hole-transporting skeleton (specifically, at least one of a π-electron-excessive heteroaromatic ring skeleton or an aromatic amine skeleton) and an electron-transporting skeleton (specifically, a π-electron-deficient heteroaromatic ring skeleton) are bonded via a bonding group having at least one of an m-phenylene group or an o-phenylene group, when bonded via a biphenyldiyl group as a bonding group, or when bonded via a bonding group having an arylene group having at least one of an m-phenylene group or an o-phenylene group, an example of the bonding group is a skeleton represented by the following general formulas (301) to (315). As the above-mentioned arylene group, a phenylene skeleton ​ , a biphenyldiyl skeleton, a naphthalenediyl skeleton, a fluorenediyl skeleton, a phenanthrenediyl skeleton, etc. can be mentioned.

[0188] [Chemical formula]

[0189] The above-mentioned aromatic amine skeleton (specifically, a triarylamine skeleton), a π-electron excess type heteroaromatic ring skeleton (specifically, a ring having at least one of an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, a thiophene skeleton, and a pyrrole skeleton), a π-electron deficient type heteroaromatic ring skeleton (specifically, a ring having at least one of a diazine skeleton and a triazine skeleton), or the above general formulas (401) to (417), general formulas (201) to (218), and general formulas (301) to (315) may have substituents. As the substituent, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 12 carbon atoms can also be selected as the substituent. Specifically, as the alkyl group having 1 to 6 carbon atoms, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, an n-hexyl group, etc. can be mentioned. Further, as the cycloalkyl group having 3 to 6 carbon atoms, specifically, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc. can be mentioned. Further, as the aryl group having 6 to 12 carbon atoms, a phenyl group, a naphthyl group, a biphenyl group, etc. can be mentioned as specific examples. Further, the above substituents may be bonded to each other to form a ring. As such an example, ​ For example, when the carbon at the 9-position in the fluorene skeleton has two phenyl groups as substituents in some cases, the phenyl groups are bonded to each other to form a spirofluorene skeleton. In the case of no substitution, it is advantageous in terms of ease of synthesis and raw material price.

[0190] Also, Ar 2 represents an arylene group having 6 to 13 carbon atoms, and the arylene group may have substituents, and the substituents may be bonded to each other to form a ring. Examples of such cases include, for example, when the carbon at the 9-position of the fluorenyl group has two phenyl groups as substituents, and the phenyl groups are bonded to each other to form a spirofluorene skeleton. Specific examples of the arylene group having 6 to 13 carbon atoms include a phenylene group, a naph thylene group, a biphenylene group, a fluorenediyl group, etc. When the arylene group has substituents, examples of the substituents include an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, an n-hexyl group, etc. Specific examples of the cycloalkyl group having 3 to 6 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc. Specific examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, etc. can also be selected as substituents. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, an n-hexyl group, etc. Also, specific examples of the cycloalkyl group having 3 to 6 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc. Further, specific examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, etc. ​​​​

[0191] Also, Ar 2 The arylene group represented by is, for example, the group represented by the above structural formula (Ar-1) to (Ar -18) can be applied. Note that Ar 2 The group that can be used as is not limited to these.

[0192] Also, R 21 and R 22 each independently represent hydrogen, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 13 carbon atoms. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, an n-hexyl group, and the like. Also, specific examples of the cycloalkyl group having 3 to 6 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and the like. Further, specific examples of the aryl group having 6 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, a fluo renyl group, and the like. Furthermore, the above-described aryl group and phenyl group may have a substituent, and the substituents may be bonded to each other to form a ring. The substituent may be selected from an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a pro pyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, an n-hexy l group, and the like. can be. yl group, a tert-butyl group, an n-hexy Examples include an Ru group. Further, as the cycloalkyl group having 3 to 6 carbon atoms, specifically, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc. can be mentioned. Further, as the aryl group having 6 to 12 carbon atoms, phenyl group, naphthyl group, biphenyl group, etc. can be mentioned as specific examples.

[0193] Further, the alkyl group or aryl group represented by R 21 and R 22 can apply, for example, the groups represented by the above structural formulas (R-1) to (R-29). Note that the groups that can be used as the alkyl group or aryl group are not limited to these.

[0194] Further, for the general formulas (401) to (417), general formulas (201) to (218), general formulas ( 301) to (315), and the substituents that Ar 2 , R 21 and R 22 can have , for example, the alkyl group or aryl group represented by the above structural formulas (R-1) to (R-24) can be applied. Note that the groups that can be used as the alkyl group or aryl group are not limited to these.

[0195] As specific structures of the compounds listed above, for example, compounds represented by the following structural formulas (500) to (50 3) can be mentioned.

[0196] [Chemical formula]

[0197] Further, the emission peak exhibited by the host material 132 is the triplet of the guest material 131 (phosphorescent material) Item MLCT (Metal to Ligand Charge Transfer) transition It is preferable to select the host material 132 and the guest material 131 (phosphorescent material) so as to overlap with the absorption band of , more specifically, the absorption band on the longest wavelength side. Thereby, 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, it is preferable that the absorption band on the longest wavelength side is a singlet absorption band.

[0198] ≪Guest material 131≫ Examples of the guest material 131 (phosphorescent material) include iridium, rhodium, or platinum-based organic metal complexes, or metal complexes. Among them, organic iridium complexes, such as iridium-based ortho-metal complexes, are preferable. Examples of the ligand for ortho-metalation include 4H-triazole ligands, 1H-triazole ligands, imidazole ligands, pyridine ligands, pyrimidine ligands, pyrazine ligands, or isoquinoline ligands. Examples of the metal complex include platinum complexes having porphyrin ligands.

[0199] In addition, as the guest material 131 (phosphorescent material), it is preferable to select the host material 132 and the guest material 131 (phosphorescent material) so that the guest material 131 has a LUMO level lower than the LUMO level of the host material 132 and has an energy difference between the LUMO level and the HOMO level higher than the energy difference between the LUMO level and the HOMO level of the host material 132. Thereby, a light-emitting device with high luminous efficiency and driven at a low voltage can be obtained.

[0200] Examples of substances having a luminescence peak in blue or green include, for example, tris{2-[5-(2 ​​​​​​​​​​​​-Methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazolo -yl-κN2]phenyl-κC}iridium(III) (abbreviation: Ir(mpp tz-dmp)3), tris(5-methyl-3,4-diphenyl-4H-1,2,4-tri azolato)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), such as organometallic iridium complexes having a 4H-triazole skeleton, and (OC-6-22)-tris{5-cyano-2- 4-(2,6-diisopropylphenyl)-5-(2-methylphenyl)-4H-1,2 4-triazol-3-yl-κN phenyl-κC}iridium(III) (abbreviation 2 : fac-Ir(mpCNptz-diPrp)3), (OC-6-21)-tris{5 -cyano-2-[4-(2,6-diisopropylphenyl)-5-(2-methylphenyl )-4H-1,2,4-triazol-3-yl-κN )-4H-1,2,4-triazol-3-yl-κN 2 phenyl-κC}iridium (III) (abbreviation: mer-Ir(mpCNptz-diPrp)3), tris{2- 4-(4-cyano-2,6-diisobutylphenyl)-5-(2-methylphenyl)-4 H-1,2,4-triazol-3-yl-κN 2 phenyl-κC}iridium(II I) (abbreviation: Ir(mpptz-diBuCNp)3) having an electron-withdrawing group such as 4H -triazole-based organometallic iridium complexes and tris[3-methyl-1-(2 -methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(I II) (abbreviation: Ir(Mptz1-mp)3), tris(1-methyl-5-phenyl-3 -propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: Ir(P Organometallic iridium complexes with 1H-triazole skeletons, such as rptz1-Me3) body and fac-tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H -imidazole]iridium(III) (abbreviation: Ir(iPrpmi)3), tris[3 -(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridin imidazoline, such as iridium(III) (abbreviation: Ir(dmpimpt-Me)3) Organometallic iridium complexes with a diol skeleton and bis[2-(4',6'-difluorophenyl)- Nyl)pyridinato-N,C 2’ ]iridium(III) tetrakis(1-pyrazolyl)borate bis[2-(4',6'-difluorophenyl)pyridinate] (abbreviation: FIr6) -N,C 2’ ]Iridium(III) picolinate (abbreviation: FIrpic), bis{2- [3',5'-Bis(trifluoromethyl)phenyl]pyridinato-N,C 2’}Iriji Ir(III) picolinate (abbreviation: Ir(CF3ppy)2(pic)), bis[2- (4',6'-Difluorophenyl)pyridinato-N,C 2’ ]Iridium(III) Phenyl groups with electron-withdrawing groups such as cetylacetonate (abbreviation: FIr(acac)) Organometallic iridium complexes having pyridine derivatives as ligands are also included. Organometallic iridium complexes having a nitrogen-containing five-membered heterocyclic skeleton such as a 4H-triazole skeleton, a 1H-triazole skeleton, and an imidazole skeleton have high triplet excitation energy and are particularly preferable because they are also excellent in reliability and luminous efficiency.

[0201] In addition, examples of substances having an emission peak in green or yellow include tris(4-methyl -6-phenylpyrimidinato)iridium(III) (abbreviation: Ir(mppm)3), tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation: I r(tBuppm)3), (acetylacetonato)bis(6-methyl-4-phenylpyr imidinato)iridium(III) (abbreviation: Ir(mppm)2(acac)), (acetyl acetonato)bis(6-tert-butyl-4-phenylpyrimidinato)iridium( III) (abbreviation: Ir(tBuppm)2(acac)), (acetylacetonato)bis [4-(2-norbornyl)-6-phenylpyrimidinato]iridium(III) (abbreviation : Ir(nbppm)2(acac)), (acetylacetonato)bis[5-methyl-6 -(2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: Ir(mpmppm)2(acac)), (acetylacetonato)bis{4,6-dimethyl -2-[6-(2,6-dimethylphenyl)-4-pyrimidinyl-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 having a pyrimidine skeleton Ruthenium complexes and organometallic iridium complexes having a pyrazine skeleton such as (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III) (abbreviation: Ir(mppr-Me)2(acac)), (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III) (abbreviation: Ir(mppr-iPr)2(acac)), and tris(2-phenylpyridinato-N,C )iridium(III) (abbreviation: Ir(ppy)3), bis(2-phenylpyridinato-N ,C )iridium(III) acetylacetonate (abbreviation: Ir(ppy)2(ac ac)), bis(benzo[h]quinolinato)iridium(III) acetylacetonate 2’ ) (abbreviation: Ir(bzq)2(acac)), tris(benzo[h]quinolinato)iridium (III) (abbreviation: Ir(bzq)3), tris(2-phenylquinolinato-N,C 2’ )iridium(III) (abbreviation: Ir(pq)3), bis(2-phenylquinolinato- N,C )iridium(III) acetylacetonate (abbreviation: Ir(pq)2(ac ac)) and other organometallic iridium complexes having a pyridine skeleton, and bis(2,4-difluorophenyl-1,3-oxazolato-N,C 2 ’ )iridium(III) acetylacetonate (abbreviation: Ir(dpo)2(acac)), bis{2-[4’-(perfluorophenyl phenyl]pyridinato-N,C 2’ )iridium(III) acetylacetonate ( abbreviation: Ir(p-PF-ph)2(acac)), bis(2-phenylbenzothiazolato -N,C 2’ )iridium(III) acetylacetonate (abbreviation: Ir(dpo)2(acac)), bis{2-[4’-(perfluorophenyl phenyl]pyridinato-N,C 2’}iridium(III) acetylacetonate( abbreviation: Ir(p-PF-ph)2(acac)), bis(2-phenylbenzothiazolato -N,C 2’)Iridium(III) acetylacetonate (abbreviation: Ir(bt)2(a cac)), in addition to organometallic iridium complexes such as tris(acetylacetonato)(monophen anthrolin) terbium(III) (abbreviation: Tb(acac)3(Phen)) and the like rare earth metal complexes can be mentioned. Among the above, organometallic iri

[0202] dium complexes having a pyrimidine skeleton are particularly preferable because they are remarkably excellent in reliability and luminescence efficiency. Also, 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)pyrim inato](dipivaloylmethanato)iridium(III) (abbreviation: Ir(d1npm)2( dpm)) and other organometallic iridium complexes having a pyrimidine skeleton, or (acetylacet onato)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), such as 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. In addition, organometallic iridium complexes having a pyrazine skeleton can obtain red luminescence with good chromaticity .

[0203] In addition, among the iridium complexes described above, organometallic iridium complexes having a pyrimidine skeleton or a pyrazine skeleton have a high electron accepting property of the ligand and tend 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 such as a fluoro group or a cyano group are also suitable because they tend to have a low LUMO level.

[0204] In addition, as the light-emitting material contained in the light-emitting layer 130 and the light-emitting layer 135, any material that can convert triplet excitation energy into light may be used. The material that can convert the triplet excitation energy into light​​ Examples of the material include thermally activated delayed fluorescence materials in addition to phosphorescent materials. Therefore, with regard to the part described as the phosphorescent material, it may be read as a thermally activated delayed fluorescence material.

[0205] ≪Host Material 133≫ As the host material 133, it is preferable to select the host material 133, the host material 132, and the guest material 131 such that the host material 133 has a HOMO level lower than that of the host material 132 and a LUMO level higher than that of the guest material 131. Thereby, a light-emitting element with high luminous efficiency and driven at a low voltage can be obtained. Note that, as the host material 133, the materials exemplified as the host material 132 may be used.

[0206] In addition, as the host material 133, a material with higher electron transportability than holes can be used, and it is preferably a material having an electron mobility of 1 × 10 -6 cm 2 / Vs or more. As a material that easily accepts electrons (a material having electron transportability), compounds having a π-electron-deficient heteroaromatic ring skeleton such as nitrogen-containing heteroaromatic compounds, 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, and oxadiazole derivatives, triazole derivatives, benzimidazole derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, phenanthroline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, triazine derivatives, and other compounds can be mentioned.

[0207] 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 Aluminum(III) (abbreviation: BAlq), bis(8-quinolinolato)zinc(II) (abbreviation: Metal complexes having a quinoline skeleton or a benzoquinoline skeleton, such as Znq, In addition, bis[2-(2-benzoxazolyl)phenolato]zinc(II)( Abbreviation: ZnPBO), bis[2-(2-benzothiazolyl)phenolato]zinc(II) ( Metal complexes with oxazole or thiazole ligands, such as ZnBTZ 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-oxadiazo 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), and other heterocyclic compounds, 2-[3-(dibenzothiophen-4-yl)phenyl] dibenz[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3’-( dibenzothiophen-4-yl)biphenyl-3-yl]dibenz[f,h]quinoxali ne (abbreviation: 2mDBTBPDBq-II), 2-[3’-(9H-carbazol-9-yl biphenyl-3-yl]dibenz[f,h]quinoxaline (abbreviation: 2mCzBPDB q), 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]di dibenz[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(diben zothiophen-4-yl)phenyl]dibenz[f,h]quinoxaline (abbreviation: 7mDB TPDBq-II), and 6-[3-(dibenzothiophen-4-yl)phenyl]di dibenz[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 2-[3-(3, 9’-bi-9H-carbazol-9-yl)phenyl]dibenz[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 {[9-(9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}- heterocyclic compounds having a triazine skeleton such as 4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 3,5-bis[3-(9H-carbazol-9-yl )phenyl]pyridine (abbreviation: 35DCzPPy), 1,3,5-tri[3-(3-pyr idyl)phenyl]benzene (abbreviation: TmPyPB) and other heterocyclic compounds having a pyridine skeleton, 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOs) and other heteroaromatic compounds can also be used. Among the above-mentioned heterocyclic compounds also, heterocyclic compounds having at least one of a triazine skeleton, a diazine (pyrimidine, pyrazine, pyridazine) skeleton, and a pyr idine skeleton are stable and have good reliability and are preferred. In addition, the heterocyclic compound having the skeleton has high electron transportability and contributes to reducing the driving voltage. Also, polymer compounds such as poly(2,5-pyridinediyl) (abbreviation: PPy), poly[(9,9-dihexyl fluorene-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 transfer mobility of 1×10 -6 cm 2 / Vs or more. As long as the substance has higher electron transportability than holes, substances other than the above can also be used.

[0208] In addition, as the host material 133, the following hole transport materials can be used.

[0209] As 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 -6 cm 2 / Vs or more. Specifically aromatic amines, carbazole derivatives, aromatic hydrocarbons, stilbene derivatives, etc. can be used . Further, the hole transporting material may be a polymer compound.

[0210] As these materials with high hole transporting property, specifically, as aromatic amine compounds, N, N’-di(p-tolyl)-N,N’-diphenyl-p-phenylenediamine (abbreviation: DT DPPA), 4,4’-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), N,N’-bis{4-[bis(3-methylphenyl yl)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 . .

[0211] Also, as carbazole derivatives, 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 ylaminophenyl)-N-(1-naphthyl)amino]-9-phenylcarbazole (abbreviation : PCzTPN2), 3-[N-(9-phenylcarbazol-3-yl)-N-phenyl Lumino]-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) and the like can be mentioned.

[0212] 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]ben zene, 2,3,5,6-tetraphenylbenzene and the like can be used.

[0213] 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)anth racene (abbreviation: DPPA), 2-tert-butyl-9,10-bis(4-phenylph enyl)anthracene (abbreviation: t-BuDBA), 9,10-di(2-naphthyl)anth racene (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 thyl)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, Years etc. 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.

[0214] 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.

[0215] In addition, poly(N-vinylcarbazole) (abbreviation: PVK) and poly(4-vinyltriphenyl ether) Nylamine) (abbreviation: PVTPA), poly[N-(4-{N'-[4-(4-diphenyl amino)phenyl]phenyl-N'-phenylamino}phenyl)methacrylamide]( abbreviation: PTPDMA), poly[N,N'-bis(4-butylphenyl)-N,N'-bis It is also possible to use a polymer compound such as (phenyl)benzidine (abbreviation: Poly-TPD). It is possible.

[0216] 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-phenylfluorene-9-yl)triphenyl ylamine (abbreviation: mBPAFLP), N-(9,9-dimethyl-9H-fluorene-2 -yl)-N-{9,9-dimethyl-2-[N'-phenyl-N'-(9,9-dimethyl -9H-fluorene-2-yl)amino]-9H-fluorene-7-yl}phenylamine (abbreviation: DFLADFL), N-(9,9-dimethyl-2-diphenylamino-9H- fluorene-7-yl)diphenylamine (abbreviation: DPNF), 2-[N-(4-diphe {[4-(p - Tolyl)phenyl](phenyl)amino}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 yl)benzene - 1,3,5 - triamine (abbreviation: PCA3B), N-(4 - biphenyl) -N-(9,9 - dimethyl - 9H - fluorene - 2 - yl)-9 - phenyl - 9H - car bazole - 3 - amine (abbreviation: PCBiF), N-(1,1'-biphenyl - 4 - yl) -N-[4-(9 - phenyl - 9H - carbazol - 3 - yl)phenyl]-9,9 - di methyl - 9H - fluorene - 2 - amine (abbreviation: PCBBiF), 9,9 - dimethyl - N -phenyl - N-[4-(9 - phenyl - 9H - carbazol - 3 - yl)phenyl]f luorene - 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-bi s[N-(4-diphenylaminophenyl)-N-phenylamino]spiro-9,9'- bifluorene (abbreviation: DPA2SF), N-[4-(9H-carbazol-9-yl)f enyl]-N-(4-phenyl)phenylaniline (abbreviation: YGA1BP), N,N'- bis[4-(carbazol-9-yl)phenyl]-N,N'-diphenyl-9,9-di methylfluorene-2,7-diamine (abbreviation: YGA2F), etc., aromatic amine compounds such as can be used. Also, 3-[4-(1-naphthyl)-phenyl]-9-phenyl -9H-carbazole (abbreviation: PCPN), 3-[4-(9-phenanthryl)-pheny l]-9-phenyl-9H-carbazole (abbreviation: PCPPn), 3,3'-bis(9- phenyl-9H-carbazole) (abbreviation: PCCP), 1,3-bis(N-carbazolyl )benzene (abbreviation: mCP), 3,6-bis(3,5-diphenylphenyl)-9-phe nylcarbazole (abbreviation: CzTP), 3,6-di(9H-carbazol-9-yl)- 9-phenyl-9H-carbazole (abbreviation: PhCzGI), 2,8-di(9H-carb azole-9-yl)-dibenzothiophene (abbreviation: Cz2DBT), 4-{3-[3-( 9-phenyl-9H-fluorene-9-yl)phenyl]phenyl}dibenzofuran (abbre viation: mmDBFFLBi-II), 4,4',4''-(benzene-1,3,5-triyl )tri(dibenzofuran) (abbreviation: DBF3P-II), 1,3,5-tri(dibenz (Thiophen-4-yl)benzene (abbreviation: DBT3P-II), 2,8-diphenyl-4 -[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), 4-[4-(9-phenyl-9H-fluoren-9- yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), 4 -[3-(Triphenylene-2-yl)phenyl]dibenzothiophene (abbreviation: mDBT PTp-II), etc., 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 at least one of a pyrrole skeleton, a furan skeleton, a thiophene skeleton, and an aromatic amine skeleton are stable and have good reliability and are preferable. In addition, the compounds having such a skeleton have high hole transportability and also contribute to reducing the driving voltage.

[0217] Note that the light-emitting layer 130 and the light-emitting layer 135 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 13 0 or the light-emitting layer 135, a material having hole transportability is used as the host material of the first light-emitting layer, and a material having electron transportability is used as the host material of the second light-emitting layer. There are configurations such as this. In addition, the light-emitting materials of the first light-emitting layer and the second light-emitting layer may be the same material or different materials, and may be materials having a function of emitting light of the same color or materials having a function of emitting light of different colors. By using light-emitting materials having functions of emitting lights of different colors in the two-layer light-emitting layer, respectively, a plurality of lights can be obtained simultaneously. It is possible. In particular, it is preferable to select the light-emitting materials used in each light-emitting layer so that the light emitted by the two light-emitting layers becomes white.

[0218] Also, in the light-emitting layer 130, it may contain materials other than the host material 132 and the guest material 131. Also, in the light-emitting layer 135, it may contain materials other than the host material 133, the host material 132, and the guest material 131.

[0219] Note that the light-emitting layer 130 and the light-emitting layer 135 can be formed by methods such as vapor deposition (including vacuum vapor deposition), inkjet printing, coating, gravure printing, etc. Also, in addition to the materials described above, it may contain inorganic compounds such as quantum dots or polymer compounds (oligomers, dendrimers, polymers, etc.).

[0220] ≪Quantum Dots≫ Quantum dots are semiconductor nanocrystals with a size ranging from several nm to several tens of nm, and are composed of about 1×10 3 to 1×10 6 atoms. Since the energy of quantum dots shifts depending on the size, even quantum dots composed of the same substance have different emission wavelengths depending on the size. Therefore, by changing the size of the quantum dots used, the emission wavelength can be easily changed.

[0221] Also, since quantum dots have a narrow peak width in the emission spectrum, it is possible to obtain light emission with good color purity. Furthermore, the theoretical internal quantum efficiency of quantum dots is said to be 100%, which is much higher than 25% of organic compounds exhibiting fluorescence emission and is equivalent to that of organic compounds exhibiting phosphorescence emission. From this, by using quantum dots as a light-emitting material, ​​​​​​​​​​​​ A light-emitting element with high luminous efficiency can be obtained. Moreover, since quantum dots, which are inorganic materials, are also excellent in their inherent stability, a preferable light-emitting element can be obtained from the viewpoint of lifespan.

[0222] Examples of materials constituting quantum dots include group 14 elements, group 15 elements, group 16 elements, compounds composed of plural group 14 elements, compounds of elements belonging to groups 4 to 14 and group 16 elements, compounds of group 2 elements and group 16 elements, compounds of group 13 elements and group 15 elements, compounds of group 13 elements and group 17 elements, compounds of group 14 elements and group 15 elements, compounds of group 11 elements and group 17 elements, iron oxides, titanium oxides, chalcogenide spinels, various semiconductor clusters, and the like.

[0223] Specifically, cadmium selenide, cadmium sulfide, cadmium telluride, zinc selenide, zinc oxide, zinc sulfide, zinc telluride, mercury sulfide, mercury selenide, mercury telluride, indium arsenide, indium phosphide, gallium arsenide, gallium phosphide, indium nitride, gallium nitride, indium antimonide, gallium antimonide, aluminum phosphide, aluminum arsenide, aluminum antimonide, lead selenide, lead telluride, lead sulfide, indium selenide, indium telluride, indium sulfide, gallium selenide, arsenic sulfide, arsenic selenide, arsenic telluride, antimony sulfide, antimony selenide, antimony telluride, bismuth sulfide, bismuth selenide, bismuth telluride, silicon, silicon carbide, germanium, tin, selenium, tellurium, boron, carbon, phosphorus, boron nitride, boron phosphide, boron arsenide , aluminum nitride, aluminum sulfide, barium sulfide, barium selenide, barium telluride, calcium sulfide, calcium selenide, calcium telluride, beryllium sulfide, beryllium selenide, beryllium telluride, magnesium sulfide, magnesium selenide, germanium sulfide, germanium selenide, germanium telluride, tin sulfide, tin selenide , tin telluride, lead oxide, copper fluoride, copper chloride, copper bromide, copper iodide, copper oxide, copper selenide, nickel oxide, cobalt oxide, cobalt sulfide, iron oxide, iron sulfide, manganese oxide, molybdenum sulfide, vanadium oxide, tungsten oxide, tantalum oxide, titanium oxide, zirconium oxide, silicon nitride, germanium nitride, aluminum oxide, barium titanate, selenium and compounds of zinc and cadmium, compounds of indium, arsenic and phosphorus, cadmium, selenium and sulfur compounds, cadmium, selenium and tellurium compounds, indium, gallium and arsenic compounds, indium, gallium and selenium compounds, indium, selenium and sulfur compounds, copper, indium and sulfur compounds, and combinations thereof, etc., but are not limited thereto. Further, so-called alloy-type quantum dots whose composition is represented by an arbitrary ratio may also be used. For example, alloy-type quantum dots of cadmium, selenium and sulfur can change the emission wavelength by changing the content ratio of the elements, and thus is one of the effective means for obtaining blue emission.

[0224] As for the structure of the quantum dots, there are core-type, core-shell type, core-multishell type, etc., and any of them may be used. However, by covering the core with another inorganic material having a wider bandgap to form a shell, defects The influence of the indium can be reduced. As a result, the quantum efficiency of luminescence is greatly improved, so the It is preferable to use core-shell type or core-multi-shell type quantum dots. Examples of the material of the shell include zinc sulfide and zinc oxide.

[0225] In addition, since quantum dots have a high proportion of surface atoms, they are highly reactive and prone to aggregation. Therefore, it is preferable that a protective agent is attached to the surface of the quantum dots or a protecting group is provided. By having the protective agent attached or the protecting group provided, aggregation can be prevented and the solubility in a solvent can be increased. Further, it is also possible to reduce the reactivity and improve the electrical stability. Examples of the protective agent (or protecting group) include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether and other polyoxyethylene alkyl ethers, tripropylphosphine, tributylphosphine, trihexylphosphine, trioctylphosphine and other trialkylphosphines, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether and other polyoxyethylene alkylphenyl ethers, tri(n-hexyl)amine, tri(n-octyl)amine, tri(n-decyl)amine and other tertiary amines, tripropylphosphine oxide, tributylphosphine oxide, trihexylphosphine oxide, trioctylphosphine oxide, tridecylphosphine oxide and other organophosphorus compounds, polyethylene glycol dilaurate, polyethylene glycol distearate and other polyethylene glycol diesters, and also ... Organic nitrogen compounds such as nitrogen-containing aromatic compounds such as pyridine, lutidine, collidine, and quinolines , aminoalkanes such as hexylamine, octylamine, decylamine, dodecylamine, tetradecylamine, hexadecylamine, octadecylamine, etc., dialkyl sulfides such as dibutyl sulfide , dialkyl sulfoxides such as dimethyl sulfoxide and dibutyl sulfoxide, organic sulfur compounds such as sulfur-containing aromatic compounds such as thiophene, palmitic acid , higher fatty acids such as stearic acid and oleic acid, alcohols, sorbitan fatty acid esters , fatty acid-modified polyesters, tertiary amine-modified polyurethanes, polyethyleneimines, etc. can be mentioned.

[0226] As the size of quantum dots decreases, the bandgap increases, so the size is appropriately adjusted so that light of a desired wavelength can be obtained. As the size of the crystal decreases, the emission of quantum dots shifts to the blue side, that is, to the high-energy side. Therefore, by changing the size of quantum dots, the emission wavelength can be adjusted over the wavelength ranges of the ultraviolet region, visible region, and infrared region. The size (diameter) of quantum dots is usually preferably in the range of 0.5 nm to 20 nm, more preferably 1 nm to 10 nm. Note that the narrower the size distribution of quantum dots, the narrower the emission spectrum becomes, and light emission with good color purity can be obtained. Also, the shape of quantum dots is not particularly limited and may be spherical, rod-shaped, disk-shaped, or other shapes. Note that quantum rods, which are rod-shaped quantum dots, have a function of exhibiting directional light. Therefore, by using quantum rods as the light-emitting material, a light-emitting device with better external quantum efficiency can be obtained.

[0227] By the way, in many cases in an organic EL element, a light-emitting material is dispersed in a host material to increase the light-emitting efficiency by suppressing concentration quenching of the light-emitting material. The host material needs to be a material having a singlet excitation energy level or a triplet excitation energy level higher than that of the light-emitting material. In particular, when a blue phosphorescent material is used as the light-emitting material, a host material having a triplet excitation energy level higher than that and excellent in terms of lifetime is required, and its development is extremely difficult. Here, since quantum dots can maintain the light-emitting efficiency even when forming a light-emitting layer using only quantum dots without using a host material, a light-emitting element favorable from the viewpoint of lifetime can be obtained also in this respect. When forming a light-emitting layer using only quantum dots, the quantum dots are preferably of a core-shell structure (including a core-multishell structure). When using quantum dots as the light-emitting material in the light-emitting layer, the film thickness of the light-emitting layer is 3 nm to 100 nm, preferably 10 nm to 100 nm, and the content of the quantum dots in the light-emitting layer is 1 to 100% by volume. However, it is preferable to form the light-emitting layer using only quantum dots. When forming a light-emitting layer in which the quantum dots are dispersed in a host as the light-emitting material, the quantum dots may be dispersed in the host material, or the host material and the quantum dots may be dissolved or dispersed in a suitable liquid medium and formed by a wet process (spin coating method, casting method, die coating method, blade coating method, roll coating method, inkjet method, printing method, spray coating method, curtain coating method, Langmuir-Blodgett method, etc.). For a light-emitting layer using a phosphorescent light-emitting material, in addition to the above wet process, a vacuum evaporation method is also preferably used. In particular, when a blue phosphorescent material is used as the light-emitting material, a host material having a triplet excitation energy level higher than that and excellent in terms of lifetime is required, and its development is extremely difficult. Here, since quantum dots can maintain the light-emitting efficiency even when forming a light-emitting layer using only quantum dots without using a host material, a light-emitting element favorable from the viewpoint of lifetime can be obtained also in this respect. When forming a light-emitting layer using only quantum dots, the quantum dots are preferably of a core-shell structure (including a core-multishell structure). In particular, when a blue phosphorescent material is used as the light-emitting material, a host material having a triplet excitation energy level higher than that and excellent in terms of lifetime is required, and its development is extremely difficult. Here, since quantum dots can maintain the light-emitting efficiency even when forming a light-emitting layer using only quantum dots without using a host material, a light-emitting element favorable from the viewpoint of lifetime can be obtained also in this respect. When forming a light-emitting layer using only quantum dots, the quantum dots are preferably of a core-shell structure (including a core-multishell structure). By the way, in many cases in an organic EL element, a light-emitting material is dispersed in a host material to increase the light-emitting efficiency by suppressing concentration quenching of the light-emitting material. The host material needs to be a material having a singlet excitation energy level or a triplet excitation energy level higher than that of the light-emitting material. In particular, when a blue phosphorescent material is used as the light-emitting material, a host material having a triplet excitation energy level higher than that and excellent in terms of lifetime is required, and its development is extremely difficult. Here, since quantum dots can maintain the light-emitting efficiency even when forming a light-emitting layer using only quantum dots without using a host material, a light-emitting element favorable from the viewpoint of lifetime can be obtained also in this respect. When forming a light-emitting layer using only quantum dots, the quantum dots are preferably of a core-shell structure (including a core-multishell structure). When using quantum dots as the light-emitting material in the light-emitting layer, the film thickness of the light-emitting layer is 3 nm to 100 nm, preferably 10 nm to 100 nm, and the content of the quantum dots in the light-emitting layer is 1 to 100% by volume. However, it is preferable to form the light-emitting layer using only quantum dots. When forming a light-emitting layer in which the quantum dots are dispersed in a host as the light-emitting material, the quantum dots may be dispersed in the host material, or the host material and the quantum dots may be dissolved or dispersed in a suitable liquid medium and formed by a wet process (spin coating method, casting method, die coating method, blade coating method, roll coating method, inkjet method, printing method, spray coating method, curtain coating method, Langmuir-Blodgett method, etc.). For a light-emitting layer using a phosphorescent light-emitting material, in addition to the above wet process, a vacuum evaporation method is also preferably used. When using quantum dots as the light-emitting material in the light-emitting layer, the film thickness of the light-emitting layer is 3 nm to 100 nm, preferably 10 nm to 100 nm, and the content of the quantum dots in the light-emitting layer is 1 to 100% by volume. However, it is preferable to form the light-emitting layer using only quantum dots. When forming a light-emitting layer in which the quantum dots are dispersed in a host as the light-emitting material, the quantum dots may be dispersed in the host material, or the host material and the quantum dots may be dissolved or dispersed in a suitable liquid medium and formed by a wet process (spin coating method, casting method, die coating method, blade coating method, roll coating method, inkjet method, printing method, spray coating method, curtain coating method, Langmuir-Blodgett method, etc.). For a light-emitting layer using a phosphorescent light-emitting material, in addition to the above wet process, a vacuum evaporation method is also preferably used.

[0228] When using quantum dots as the light-emitting material in the light-emitting layer, the film thickness of the light-emitting layer is 3 nm to 100 nm, preferably 10 nm to 100 nm, and the content of the quantum dots in the light-emitting layer is 1 to 100% by volume. However, it is preferable to form the light-emitting layer using only quantum dots. When forming a light-emitting layer in which the quantum dots are dispersed in a host as the light-emitting material, the quantum dots may be dispersed in the host material, or the host material and the quantum dots may be dissolved or dispersed in a suitable liquid medium and formed by a wet process (spin coating method, casting method, die coating method, blade coating method, roll coating method, inkjet method, printing method, spray coating method, curtain coating method, Langmuir-Blodgett method, etc.). For a light-emitting layer using a phosphorescent light-emitting material, in addition to the above wet process, a vacuum evaporation method is also preferably used. When using quantum dots as the light-emitting material in the light-emitting layer, the film thickness of the light-emitting layer is 3 nm to 100 nm, preferably 10 nm to 100 nm, and the content of the quantum dots in the light-emitting layer is 1 to 100% by volume. However, it is preferable to form the light-emitting layer using only quantum dots. When forming a light-emitting layer in which the quantum dots are dispersed in a host as the light-emitting material, the quantum dots may be dispersed in the host material, or the host material and the quantum dots may be dissolved or dispersed in a suitable liquid medium and formed by a wet process (spin coating method, casting method, die coating method, blade coating method, roll coating method, inkjet method, printing method, spray coating method, curtain coating method, Langmuir-Blodgett method, etc.). For a light-emitting layer using a phosphorescent light-emitting material, in addition to the above wet process, a vacuum evaporation method is also preferably used. When using quantum dots as the light-emitting material in the light-emitting layer, the film thickness of the light-emitting layer is 3 nm to 100 nm, preferably 10 nm to 100 nm, and the content of the quantum dots in the light-emitting layer is 1 to 100% by volume. However, it is preferable to form the light-emitting layer using only quantum dots. When forming a light-emitting layer in which the quantum dots are dispersed in a host as the light-emitting material, the quantum dots may be dispersed in the host material, or the host material and the quantum dots may be dissolved or dispersed in a suitable liquid medium and formed by a wet process (spin coating method, casting method, die coating method, blade coating method, roll coating method, inkjet method, printing method, spray coating method, curtain coating method, Langmuir-Blodgett method, etc.). For a light-emitting layer using a phosphorescent light-emitting material, in addition to the above wet process, a vacuum evaporation method is also preferably used. When using quantum dots as the light-emitting material in the light-emitting layer, the film thickness of the light-emitting layer is 3 nm to 100 nm, preferably 10 nm to 100 nm, and the content of the quantum dots in the light-emitting layer is 1 to 100% by volume. However, it is preferable to form the light-emitting layer using only quantum dots. When forming a light-emitting layer in which the quantum dots are dispersed in a host as the light-emitting material, the quantum dots may be dispersed in the host material, or the host material and the quantum dots may be dissolved or dispersed in a suitable liquid medium and formed by a wet process (spin coating method, casting method, die coating method, blade coating method, roll coating method, inkjet method, printing method, spray coating method, curtain coating method, Langmuir-Blodgett method, etc.). For a light-emitting layer using a phosphorescent light-emitting material, in addition to the above wet process, a vacuum evaporation method is also preferably used. When using quantum dots as the light-emitting material in the light-emitting layer, the film thickness of the light-emitting layer is 3 nm to 100 nm, preferably 10 nm to 100 nm, and the content of the quantum dots in the light-emitting layer is 1 to 100% by volume. However, it is preferable to form the light-emitting layer using only quantum dots. When forming a light-emitting layer in which the quantum dots are dispersed in a host as the light-emitting material, the quantum dots may be dispersed in the host material, or the host material and the quantum dots may be dissolved or dispersed in a suitable liquid medium and formed by a wet process (spin coating method, casting method, die coating method, blade coating method, roll coating method, inkjet method, printing method, spray coating method, curtain coating method, Langmuir-Blodgett method, etc.). For a light-emitting layer using a phosphorescent light-emitting material, in addition to the above wet process, a vacuum evaporation method is also preferably used. When using quantum dots as the light-emitting material in the light-emitting layer, the film thickness of the light-emitting layer is 3 nm to 100 nm, preferably 10 nm to 100 nm, and the content of the quantum dots in the light-emitting layer is 1 to 100% by volume. However, it is preferable to form the light-emitting layer using only quantum dots. When forming a light-emitting layer in which the quantum dots are dispersed in a host as the light-emitting material, the quantum dots may be dispersed in the host material, or the host material and the quantum dots may be dissolved or dispersed in a suitable liquid medium and formed by a wet process (spin coating method, casting method, die coating method, blade coating method, roll coating method, inkjet method, printing method, spray coating method, curtain coating method, Langmuir-Blodgett method, etc.). For a light-emitting layer using a phosphorescent light-emitting material, in addition to the above wet process, a vacuum evaporation method is also preferably used. When using quantum dots as the light-emitting material in the light-emitting layer, the film thickness of the light-emitting layer is 3 nm to 100 nm, preferably 10 nm to 100 nm, and the content of the quantum dots in the light-emitting layer is 1 to 100% by volume. However, it is preferable to form the light-emitting layer using only quantum dots. When forming a light-emitting layer in which the quantum dots are dispersed in a host as the light-emitting material, the quantum dots may be dispersed in the host material, or the host material and the quantum dots may be dissolved or dispersed in a suitable liquid medium and formed by a wet process (spin coating method, casting method, die coating method, blade coating method, roll coating method, inkjet method, printing method, spray coating method, curtain coating method, Langmuir-Blodgett method, etc.). For a light-emitting layer using a phosphorescent light-emitting material, in addition to the above wet process, a vacuum evaporation method is also preferably used. When using quantum dots as the light-emitting material in the light-emitting layer, the film thickness of the light-emitting layer is 3 nm to 100 nm, preferably 10 nm to 100 nm, and the content of the quantum dots in the light-emitting layer is 1 to 100% by volume. However, it is preferable to form the light-emitting layer using only quantum dots. When forming a light-emitting layer in which the quantum dots are dispersed in a host as the light-emitting material, the quantum dots may be dispersed in the host material, or the host material and the quantum dots may be dissolved or dispersed in a suitable liquid medium and formed by a wet process (spin coating method, casting method, die coating method, blade coating method, roll coating method, inkjet method, printing method, spray coating method, curtain coating method, Langmuir-Blodgett method, etc.). For a light-emitting layer using a phosphorescent light-emitting material, in addition to the above wet process, a vacuum evaporation method is also preferably used. When using quantum dots as the light-emitting material in the light-emitting layer, the film thickness of the light-emitting layer is 3 nm to 100 nm, preferably 10 nm to 100 nm, and the content of the quantum dots in the light-emitting layer is 1 to 100% by volume. However, it is preferable to form the light-emitting layer using only quantum dots. When forming a light-emitting layer in which the quantum dots are dispersed in a host as the light-emitting material, the quantum dots may be dispersed in the host material, or the host material and the quantum dots may be dissolved or dispersed in a suitable liquid medium and formed by a wet process (spin coating method, casting method, die coating method, blade coating method, roll coating method, inkjet method, printing method, spray coating method, curtain coating method, Langmuir-Blodgett method, etc.). For a light-emitting layer using a phosphorescent light-emitting material, in addition to the above wet process, a vacuum evaporation method is also preferably used. It is possible.

[0229] As the liquid medium used in the wet process, for example, ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, aromatic hydrocarbons such as toluene, xylene, mesitylene, and cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin, and dodecane, organic solvents such as dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) can be used. ketones such as cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, aromatic hydrocarbons such as toluene, xylene, mesitylene, and cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin, and dodecane, dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and other organic solvents can be used. It is possible.

[0230] ≪Hole injection layer≫ The hole injection layer 111 has a function of promoting hole injection by reducing the hole injection barrier from one of the pair of electrodes (electrode 101 or electrode 102), and is formed by, for example, transition metal oxides, phthalocyanine derivatives, or aromatic amines. Examples of transition metal oxides include molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, and manganese oxide. Examples of phthalocyanine derivatives include phthalocyanine and metal phthalocyanine. Examples of aromatic amines include benzidine derivatives and phenylenediamine derivatives. Polymer compounds such as polythiophene and polyaniline can also be used, and for example, poly(ethylenedioxythiophene) / poly(styrenesulfonic acid), which is self-doped polythiophene, is a typical example. It has a function of promoting hole injection by reducing the hole injection barrier from one of the pair of electrodes (electrode 101 or electrode 102), and is formed by, for example, transition metal oxides, phthalocyanine derivatives, or aromatic amines. or aromatic amines. Transition metal oxides include molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, manganese oxide, etc. Phthalocyanine derivatives include phthalocyanine and metal phthalocyanine. Aromatic amines include benzidine derivatives and phenylenediamine derivatives. Polymer compounds such as polythiophene and polyaniline can also be used, and for example, poly(ethylenedioxythiophene) / poly(styrenesulfonic acid), which is self-doped polythiophene, is a typical example. Examples of phthalocyanine derivatives include phthalocyanine and metal phthalocyanine. Examples of aromatic amines include benzidine derivatives and phenylenediamine derivatives. Polymer compounds such as polythiophene and polyaniline can also be used, and for example, poly(ethylenedioxythiophene) / poly(styrenesulfonic acid), which is self-doped polythiophene, is a typical example. As the hole injection layer 111, a layer having a composite material of a hole transporting material and a material showing electron accepting property with respect to this can also be used. Alternatively, a layer containing a material showing electron accepting property and a positive

[0231] As the hole injection layer 111, a layer having a composite material of a hole transporting material and a material showing electron accepting property with respect to this can also be used. Alternatively, a layer containing a material showing electron accepting property 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 (halogen group or cyano group) such as 7,7,8,8 - tetracyano - 2,3,5,6 - tetrafluorobenzoquinodimethane (abbreviation: F4 - TCNQ), chloranil, 2,3,6,7,10,11 - hexacyano - 1,4,5,8,9,12 - hexaazatriphenylene (abbreviation: HAT - CN), 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 these, molybdenum oxide is preferred because it is stable in air, has low hygroscopicity, and is easy to handle. As the hole transporting material, a material having 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 can be used. Also, the hole transporting material may be a polymer compound. ≪Hole Transporting Layer≫ The hole transporting layer 112 is a layer containing a hole transporting material, and as an example of the material of the hole injection layer 111

[0232] -6 2

[0233] The shown hole transporting material can be used. Since the hole transport layer 112 has a function of transporting the holes injected into the hole injection layer 111 to the light emitting layer, it preferably has the same or a similar HOMO level as the highest occupied molecular orbital (also referred to as HOMO) level of the hole injection layer 111. Moreover, it is preferably a material having a hole mobility of 1×10 (Highest Occupied Molecular Orbital, HOMO also called) level or more. However, as long as it is a material with higher hole transportability than electrons, other materials may be used.

[0234] Note that the layer containing a material with high hole transportability may be not only a single layer, but also two or more layers of the above materials laminated. -6 cm 2 / Vs or more. However, as long as it is a material with higher hole transportability than electrons, other materials may be used. Note that the layer containing a material with high hole transportability may be not only a single layer, but also two or more layers of the above materials laminated. ≪Electron transport layer≫

[0235] The electron transport layer 118 has a function of transporting the electrons injected from the other of the pair of electrodes (electrode 101 or electrode 102) through the electron injection layer 119 to the light emitting layer. As the electron transporting material, a material with higher electron transportability than holes can be used, and it is preferably a material having an electron mobility of 1×10 As the electron transporting material, a material with higher electron transportability than holes can be used, and it is preferably a material having an electron mobility of 1×10 As the electron transporting material, a material with higher electron transportability than holes can be used, and it is preferably a material having an electron mobility of 1×10 As the electron transporting material, a material with higher electron transportability than holes can be used, and it is preferably a material having an electron mobility of 1×10 -6 cm 2 / Vs or more. As a compound that easily receives electrons (a material having electron transportability), a π-electron deficient heteroaromatic compound such as a nitrogen-containing heteroaromatic compound or a metal complex can be used. Specifically, as the electron transporting material that can be used for the light emitting layer, the quinoline ligand, the benzoquinoline ligand, the oxazole ligand, or the metal complex having a thiazole ligand, the oxadiazole derivative, the triazole derivative, the benzimidazole derivative, the quinoxaline derivative, the dibenzoquinoxaline As a compound that easily receives electrons (a material having electron transportability), a π-electron deficient heteroaromatic compound such as a nitrogen-containing heteroaromatic compound or a metal complex can be used. Specifically, as the electron transporting material that can be used for the light emitting layer, the quinoline ligand, the benzoquinoline ligand, the oxazole ligand, or the metal complex having a thiazole ligand, the oxadiazole derivative, the triazole derivative, the benzimidazole derivative, the quinoxaline derivative, the dibenzoquinoxaline As a compound that easily receives electrons (a material having electron transportability), a π-electron deficient heteroaromatic compound such as a nitrogen-containing heteroaromatic compound or a metal complex can be used. Specifically, as the electron transporting material that can be used for the light emitting layer, the quinoline ligand, the benzoquinoline ligand, the oxazole ligand, or the metal complex having a thiazole ligand, the oxadiazole derivative, the triazole derivative, the benzimidazole derivative, the quinoxaline derivative, the dibenzoquinoxaline As a compound that easily receives electrons (a material having electron transportability), a π-electron deficient heteroaromatic compound such as a nitrogen-containing heteroaromatic compound or a metal complex can be used. Specifically, as the electron transporting material that can be used for the light emitting layer, the quinoline ligand, the benzoquinoline ligand, the oxazole ligand, or the metal complex having a thiazole ligand, the oxadiazole derivative, the triazole derivative, the benzimidazole derivative, the quinoxaline derivative, the dibenzoquinoxaline As a compound that easily receives electrons (a material having electron transportability), a π-electron deficient heteroaromatic compound such as a nitrogen-containing heteroaromatic compound or a metal complex can be used. Specifically, as the electron transporting material that can be used for the light emitting layer, the quinoline ligand, the benzoquinoline ligand, the oxazole ligand, or the metal complex having a thiazole ligand, the oxadiazole derivative, the triazole derivative, the benzimidazole derivative, the quinoxaline derivative, the dibenzoquinoxaline As a compound that easily receives electrons (a material having electron transportability), a π-electron deficient heteroaromatic compound such as a nitrogen-containing heteroaromatic compound or a metal complex can be used. Specifically, as the electron transporting material that can be used for the light emitting layer, the quinoline ligand, the benzoquinoline ligand, the oxazole ligand, or the metal complex having a thiazole ligand, the oxadiazole derivative, the triazole derivative, the benzimidazole derivative, the quinoxaline derivative, the dibenzoquinoxaline Derivatives, phenanthroline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives and triazine derivatives. -6 cm 2 / Vs or more electron transfer It is preferable that the material has a higher electron transporting property than the hole transporting property. If desired, a material other than the above may be used for the electron transport layer. The layer may be a single layer or may be a laminate of two or more layers made of the above-mentioned materials.

[0236] Furthermore, a layer for controlling the movement of electron carriers may be provided between the electron transport layer 118 and the light emitting layer. This is because a small amount of a substance with high electron trapping properties is added to a material with high electron transport properties as described above. It is a doped layer that suppresses the movement of electron carriers, thereby improving the carrier balance. This structure prevents electrons from penetrating the light-emitting layer. This is highly effective in suppressing problems that arise from this (for example, a reduction in the lifespan of the element).

[0237] Alternatively, n-type compound semiconductors may be used, such as titanium oxide, zinc oxide, and silicon oxide. element, tin oxide, tungsten oxide, tantalum oxide, barium titanate, barium zirconate , zirconium oxide, hafnium oxide, aluminum oxide, yttrium oxide, silicate Oxides such as zinc, nitrides such as silicon nitride, cadmium sulfide, zinc selenide and zinc sulfide, etc. can also be used.

[0238] ≪Electron injection layer≫ The electron injection layer 119 promotes electron injection by reducing the electron injection barrier from the electrode 102. For example, Group 1 metals, Group 2 metals, or their oxides and halides , carbonates, etc. can be used. Further, a composite material of the previously described electron transport material and a material exhibiting electron donating properties can also be used. Examples of materials exhibiting electron donating properties include Group 1 metals, Group 2 metals, or oxides thereof. Specifically, lithium fluoride, sodium fluoride, cesium fluoride, calcium fluoride, lithium oxide, etc., such as alkali metals, alkaline earth metals, or compounds thereof can be used. Further, rare earth metal compounds such as erbium fluoride can be used. Also, an electride may be used for the electron injection layer 119. Examples of the electride include substances obtained by adding electrons at a high concentration to a mixed oxide of calcium and aluminum. Also, a substance that can be used in the electron transport layer 118 may be used for the electron injection layer 119. For example, substances obtained by adding electrons at a high concentration to a mixed oxide of calcium and aluminum. Also, a substance that can be used in the electron transport layer 118 may be used for the electron injection layer 119.

[0239] Further, a composite material formed by mixing an organic compound and an electron donor may be used for the electron injection layer 119. Such a composite material generates electrons in the organic compound by the electron donor, and thus has excellent electron injection properties and electron transport properties. In this case, the organic compound is preferably a material excellent in transporting the generated electrons. Specifically, for example, the substances constituting the above-described electron transport layer 118 (metal complexes, heteroaromatic compounds, etc.) can be used. As the electron donor, any substance that exhibits electron donating properties with respect to the organic compound may be used. Specifically, alkali metals, alkaline earth metals, and rare earth metals are preferable, and examples include lithium, sodium, [[ID=2)]] cesium, magnesium, calcium, erbium, ytterbium, etc. Also, alkali metal oxides and alkaline earth metal oxides are preferable, and examples include lithium oxide, calcium )]]oxide. Examples of oxides include sodium oxide and barium oxide. Lewis oxides such as magnesium oxide are also included. A base can also be used. In addition, organic compounds such as tetrathiafulvalene (TTF) can be used. You can also use objects.

[0240] The above-mentioned light-emitting layer, hole-injection layer, hole-transport layer, electron-transport layer, and electron-injection layer are These methods include vapor deposition (including vacuum deposition), inkjet printing, coating, and gravure printing. The light-emitting layer, the hole-injecting layer, the hole-transporting layer, the electron In addition to the materials mentioned above, inorganic compounds such as quantum dots and high molecular weight compounds can be used for the transport layer and electron injection layer. A polymer compound (oligomer, dendrimer, polymer, etc.) may also be used.

[0241] <Pair of electrodes> The electrode 101 and the electrode 102 function as an anode or a cathode of the light-emitting element. The electrode 101 and the electrode 102 may be made of a metal, an alloy, a conductive compound, or a mixture or laminate thereof. It can be formed using, for example.

[0242] One of the electrodes 101 and 102 is made of a conductive material that has a function of reflecting light. The conductive material is preferably aluminum (Al) or a compound containing Al. Examples of alloys containing Al include Al and L (L is titanium (Ti), neodymium (Ne), etc. (representing one or more of Nd, Ni, and La) Examples of suitable alloys include alloys containing Al and Ti, or alloys containing Al, Ni and La. Aluminum has low resistance and high light reflectivity. Since aluminum is abundant and inexpensive, the cost of manufacturing a light-emitting element using aluminum is reduced. It is possible to reduce the 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 one or more of gold (Au) may be used. Examples of alloys containing silver include alloys containing silver, palladium, and copper, alloys containing silver and copper, alloys containing silver and magnesium , alloys containing silver and nickel, alloys containing silver and gold, alloys containing silver and ytterbium , etc. In addition, transition metals such as tungsten, chromium (Cr), molybdenum (Mo ), copper, and titanium can be used.

[0243] Also, 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 electrodes 101 and 102 is preferably formed of a conductive material having a function of transmitting light . Examples of such a conductive material include those having a visible light transmittance of 40% or more and 100% or less, preferably 60% or more and 100% or less, and a resistivity of 1×10 Ω·cm or less. -2

[0244] Also, the electrodes 101 and 102 may be formed of a conductive material having a function of transmitting light and a function of reflecting light . Examples of such a conductive material include those having a visible light reflectance of 20 % or more and 80% or less, preferably 40% or more and 70% or less, and a resistivity of 1×10 -2 Ω·cm or less. For example, conductive metals, alloys, conductive It can be formed using one or more kinds of sex compounds, etc. Specifically, for example, indium tin oxide (Indium Tin Oxide, hereinafter referred to as ITO), silicon or silicon oxide containing indium tin oxide (abbreviation: ITSO), indium zinc oxide (Indi um Zinc Oxide), indium tin oxide containing titanium, indium titanium oxide, indium oxide containing tungsten oxide and zinc oxide, etc. of metal oxides can be used. In addition, 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 alloys such as Ag and Al, Ag and Mg, Ag and Au, Ag and Yb, etc. can be used.

[0245] 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 typified by the above-mentioned 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. are exemplified

[0246] 5 Ω·cm or less, more preferably 1×10 4 Ω·cm or less.

[0246] In addition, one or both of the electrode 101 and the electrode 102 may be formed by laminating a plurality of the above materials.

[0247] ​In addition, in order to improve the light extraction efficiency, a material having a refractive index higher than that of the electrode may be formed in contact with the electrode having a function of transmitting light. Such materials may be materials having a function of transmitting visible light, and may be conductive materials or non-conductive materials. 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. Further, inorganic carbon-based materials and metals in the form of thin films through which light can pass can also 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. When electrode 101 or electrode 102 functions as a cathode, it preferably has a material with 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, cesium, etc., alkaline earth metals such as calcium, strontium, etc., magnesium, etc.), alloys containing these elements (for example, Ag and Mg, Al and Li), rare earth metals such as europium (Eu), Yb, alloys containing these rare earth metals, aluminum, alloys containing silver, etc. can be used. When electrode 101 or electrode 102 is used as an anode, it is preferable to use a material with a large work function (4.0 eV or more). In addition, electrodes 101 and 102 may be formed as 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, electrodes 101 and 1 02 For example, materials such as those exemplified for the light emitting layer, hole injection layer, hole transport layer, electron transport layer, or electron injection layer can be used as the organic substance. Further, inorganic carbon-based materials and metals in the form of thin films through which light can pass can also 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. In addition, in order to improve the light extraction efficiency, a material having a refractive index higher than that of the electrode may be formed in contact with the electrode having a function of transmitting light. Such materials may be materials having a function of transmitting visible light, and may be conductive materials or non-conductive materials. For example, in addition to the above-described oxide conductors, oxide semiconductors and organic substances may be mentioned. When electrode 101 or electrode 102 functions as a cathode, it preferably has a material with 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, cesium, etc., alkaline earth metals such as calcium, strontium, etc., magnesium, etc.), alloys containing these elements (for example, Ag and Mg, Al and Li), rare earth metals such as europium (Eu), Yb, alloys containing these rare earth metals, aluminum, alloys containing silver, etc. can be used.

[0248] When electrode 101 or electrode 102 functions as a cathode, it preferably has a material with 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, cesium, etc., alkaline earth metals such as calcium, strontium, etc., magnesium, etc.), alloys containing these elements (for example, Ag and Mg, Al and Li), rare earth metals such as europium (Eu), Yb, alloys containing these rare earth metals, aluminum, alloys containing silver, etc. can be used. For example, elements belonging to Group 1 or Group 2 of the periodic table (alkali metals such as lithium, sodium, cesium, etc., alkaline earth metals such as calcium, strontium, etc., magnesium, etc.), alloys containing these elements (for example, Ag and Mg, Al and Li), rare earth metals such as europium (Eu), Yb, alloys containing these rare earth metals, aluminum, alloys containing silver, etc. can be used. When electrode 101 or electrode 102 functions as a cathode, it preferably has a material with 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, cesium, etc., alkaline earth metals such as calcium, strontium, etc., magnesium, etc.), alloys containing these elements (for example, Ag and Mg, Al and Li), rare earth metals such as europium (Eu), Yb, alloys containing these rare earth metals, aluminum, alloys containing silver, etc. can be used. When electrode 101 or electrode 102 functions as a cathode, it preferably has a material with 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, cesium, etc., alkaline earth metals such as calcium, strontium, etc., magnesium, etc.), alloys containing these elements (for example, Ag and Mg, Al and Li), rare earth metals such as europium (Eu), Yb, alloys containing these rare earth metals, aluminum, alloys containing silver, etc. can be used. When electrode 101 or electrode 102 functions as a cathode, it preferably has a material with 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, cesium, etc., alkaline earth metals such as calcium, strontium, etc., magnesium, etc.), alloys containing these elements (for example, Ag and Mg, Al and Li), rare earth metals such as europium (Eu), Yb, alloys containing these rare earth metals, aluminum, alloys containing silver, etc. can be used. When electrode 101 or electrode 102 functions as a cathode, it preferably has a material with 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, cesium, etc., alkaline earth metals such as calcium, strontium, etc., magnesium, etc.), alloys containing these elements (for example, Ag and Mg, Al and Li), rare earth metals such as europium (Eu), Yb, alloys containing these rare earth metals, aluminum, alloys containing silver, etc. can be used.

[0249] When electrode 101 or electrode 102 is used as an anode, it is preferable to use a material with a large work function (4.0 eV or more). When electrode 101 or electrode 102 is used as an anode, it is preferable to use a material with a large work function (4.0 eV or more).

[0250] In addition, electrodes 101 and 102 may be formed as 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, electrodes 101 and 102 02 can resonate light of a desired wavelength from each light-emitting layer and enhance the light of the desired wavelength, so it is preferable because it can have a function of adjusting the optical distance.

[0251] The film-forming methods of the electrode 101 and the electrode 102 include 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., which can be appropriately used. It can be.

[0252] ≪Substrate≫ In addition, the light-emitting element according to one aspect of the present invention may be manufactured on a substrate made of glass, plastic, etc. As the order of manufacturing on the substrate, it may be laminated in order from the electrode 101 side or from the electrode 102 side in order.

[0253] Note that as the substrate on which the light-emitting element according to one aspect of the present invention can be formed, for example, glass, quartz , or plastic can be used. A flexible substrate may also be used. A flexible substrate 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, etc. can also be used. Note that as long as it functions as a support in the manufacturing process of the light-emitting element and the optical element, other things may be used. Alternatively, as long as it has a function of protecting the light-emitting element and the optical element.

[0254] For example, in the present invention and the like, a light-emitting element can be formed using various substrates. The type of the substrate is not limited to a specific one. As an example of the substrate, a semiconductor substrate A board (e.g., a single-crystal substrate or a silicon substrate), an SOI substrate, a glass substrate, a quartz substrate, a plastic chip substrate, a metal substrate, a stainless-steel substrate, a substrate having a stainless-steel foil substrate, a tungsten substrate, a substrate having a tungsten foil, a flexible substrate, a laminated film, a paper containing a fibrous material, or a base film, etc. As an example of the glass substrate there are barium borosilicate glass, aluminoborosilicate glass, or soda-lime glass etc. As an example of a flexible substrate, a laminated film, a base film, etc., the following are given. For example, plastics represented by polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polytetrafluoroethylene (PTFE). Or, as an example, there are resins such as acrylic. Or, as an example, there are polypropylene, polyester, polyvinyl fluoride , or polyvinyl chloride, etc. Or, as an example, there are polyamide, polyimide, aramid, epoxy, an inorganic vapor deposition film, or papers, etc.

[0255] Also, as the substrate, a flexible substrate may be used, and a light-emitting element may be directly formed on the flexible substrate . Or, a release layer may be provided between the substrate and the light-emitting element. The release layer is used to separate from the substrate after partially or completely completing the light-emitting element thereon and transfer it to another substrate. At that time, the light-emitting element can be transferred to a substrate with poor heat resistance or a flexible substrate. Also , for the above-mentioned release layer, for example, a laminated structure of an inorganic film of a tungsten film and a silicon oxide film , or a structure in which a resin film such as polyimide is formed on the substrate can be used .

[0256] ​That is, a light-emitting element is formed using a certain substrate, and then the light-emitting element is transferred to another substrate. 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 substrates 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 exists. 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.

[0257] In addition, for example, a field effect transistor (FET) may be formed on the above-described substrate, and the light-emitting element 150 may be fabricated on an electrode electrically connected to the FET. Thereby, an active matrix type display device that controls the driving of the light-emitting element 150 by the FET can be fabricated.

[0258] In the present embodiment, one aspect of the present invention has been described. Or, in other embodiments, one aspect of the present invention is described. However, one aspect of the present invention is not limited to these. That is, in the present 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 an example of one aspect of the present invention, an example when applied to a light-emitting element is shown, but one aspect of the present invention is not limited thereto. For example, in some cases, or depending on the situation, one aspect of the present invention may not be applied to a light-emitting element. Or, for example, in one aspect of the present invention, a guest material having a function capable of converting triplet excitation energy into light emission and at least one host material are included. ​​​​​​​​​Moreover, an example is shown where the LUMO level of the guest material is lower than the LUMO level of the host material, and the energy difference between the LUMO level and the HOMO level of the guest material is greater than the energy difference between the LUMO level and the HOMO level of the host material. However, 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 guest material may not have a function of converting triplet excitation energy into light emission. Alternatively, the LUMO level of the guest material may not be lower than the LUMO level of the host material. Alternatively, the energy difference between the LUMO level and the HOMO level of the guest material may not be greater than the energy difference between the LUMO level and the HOMO level of the host material. Further, for example, in one aspect of the present invention, an example is shown where the difference between the singlet excitation energy level and the triplet excitation energy level of the host material is greater than 0 eV and 0.2 eV or less. However, 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 difference between the singlet excitation energy level and the triplet excitation energy level of the host material may be greater than 0.2 eV. The energy difference between the LUMO level and the HOMO level of the guest material is greater than the energy difference between the LUMO level and the HOMO level of the host material. has been shown. However, 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 guest material may not have a function of converting triplet excitation energy into light emission. Alternatively, the LUMO level of the guest material may not be lower than the LUMO level of the host material. Alternatively, the energy difference between the LUMO level and the HOMO level of the guest material may not be greater than the energy difference between the LUMO level and the HOMO level of the host material. Further, for example, in one aspect of the present invention, the host material has an example where the difference between the singlet excitation energy level and the triplet excitation energy level is greater than 0 eV and 0.2 eV or less. However, 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 host material may have a difference between the singlet excitation energy level and the triplet excitation energy level of 0. It may be greater than 2 eV.

[0259] As described above, the configuration shown in the present embodiment can be used in appropriate combination with other embodiments.

[0260] (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 , and the light-emitting mechanism of the light-emitting element will be described below with reference to FIGS. 5 and 6. Note that , in FIGS. 5(A) and 6(A), portions having the same functions as the reference numerals shown in FIG. 1(A) are shown with the same hatch pattern, and the reference numerals may be omitted. Further, portions having the same functions​ Parts to which the same reference numerals are attached may have a similar description omitted for simplicity.

[0261] <Example Configuration 1 of Light-Emitting Element> FIG. 5(A) is a schematic cross-sectional view of a light-emitting element 250.

[0262] The light-emitting element 250 shown in FIG. 5(A) has a plurality of light-emitting units (light-emitting unit 106 and light-emitting unit 108 in FIG. 5(A)) between a pair of electrodes (electrode 101 and electrode 102). Preferably, any one of the plurality of light-emitting units has a configuration similar to that of the EL layer 100. That is, the light-emitting element 150 shown in FIG. 1 and the light-emitting element 152 shown in FIG. 3 each have 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 electrode 101 functions as an anode and electrode 102 functions as a cathode in the following description, the configuration of the light-emitting element 250 may be reversed. 08).

[0263] In the light-emitting element 250 shown in FIG. 5(A), the light-emitting unit 106 and the light-emitting unit 108 are stacked, and a charge generation layer 115 is provided between the light-emitting unit 106 and the light-emitting unit 108. 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 for the light-emitting unit 106.

[0264] The light-emitting element 250 also has a light-emitting layer 120 and a light-emitting layer 170. The light-emitting unit 106 has, in addition to the light-emitting layer 170, a hole injection layer 111, a hole transport layer 112, an electron transport layer 113, and an electron injection layer 114. The light-emitting unit 108 has the light-emitting layer 120. ​​​​​​​​​​​ In addition to the above, a hole injection layer 116, a hole transport layer 117, an electron transport layer 118, and an electron injection layer 11 It has 9.

[0265] The charge generation layer 115 is formed by adding an acceptor material, which is an electron acceptor, to a hole transport material. Even if the electron transport material is an electron donor, a donor material may be added to the electron transport material. Alternatively, both of these structures may be stacked.

[0266] When the charge generation layer 115 contains a composite material of an organic compound and an acceptor substance, the The composite material that can be used for the hole-injection layer 111 shown in Embodiment 1 is used as the composite material. The organic compounds include aromatic amine compounds, carbazole compounds, aromatic carbonized compounds, and the like. Various compounds such as hydrogen and polymer compounds (oligomers, dendrimers, polymers, etc.) are used. As for organic compounds, those with a hole mobility of 1×10 -6 cm 2 / Vs However, it is preferable to use a material having a higher hole transporting property than an electron transporting property. Other materials may be used as long as they are compatible with the organic compound and the acceptor material. The material has excellent carrier injection and carrier transport properties, allowing for low voltage and low current operation. In addition, the anode side of the light-emitting unit is in contact with the charge generating layer 115. In this case, the charge generation layer 115 also serves as a hole injection layer or a hole transport layer for the light-emitting unit. Therefore, the light-emitting unit does not need to have a hole injection layer or a hole transport layer. Alternatively, when the cathode side surface of the light-emitting unit is in contact with the charge generating layer 115, The charge generation layer 115 also serves as an electron injection layer or an electron transport layer for the light-emitting unit. Since this is possible, the light-emitting unit may be configured without an electron injection layer or an electron transport layer. This is acceptable.

[0267] 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 with a layer containing one compound selected from electron-donating substances and a compound with high electron transport properties. Further, it may be formed by combining a layer containing a composite material of an organic compound and an acceptor material with a layer containing a transparent conductive film. This is acceptable.

[0268] 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. 5(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 holes into the light-emitting unit 108. This is acceptable. This is acceptable.

[0269] Note that the charge generation layer 115 preferably has translucency with respect to visible light (specifically, the transmittance of visible light with respect to the charge generation layer 115 is 40% or more) from the viewpoint of light extraction efficiency. Further, the charge generation layer 115 can function even if it has a lower conductivity than a pair of electrodes (the electrode 101 and the electrode 102). This is acceptable.

[0270] By forming the charge generation layer 115 using the materials described above, an increase in the driving voltage in the case where the light-emitting layers are laminated can be suppressed. This is acceptable.

[0271] In addition, in FIG. 5(A), a light-emitting element having two light-emitting units was described. However, it can be similarly applied to a light-emitting element in which three or more light-emitting units are stacked. As shown in the light-emitting element 250, by arranging a plurality of light-emitting units between a pair of electrodes with a charge generation layer interposed therebetween, high-brightness light emission is enabled while keeping the current density low, and furthermore a long-life light-emitting element can be realized. Also, a light-emitting element with low power consumption can be realized. .

[0272] Note that by applying the configuration shown in Embodiment 1 to at least one of the plurality of units, a light-emitting element with high luminous efficiency can be provided.

[0273] In addition, the light-emitting layer 170 included in the light-emitting unit 106 preferably has the configuration of the light-emitting layer 13 0 or the light-emitting layer 135 shown in Embodiment 1. By doing so, the light-emitting element 250 becomes a light-emitting element with high luminous efficiency and is suitable.

[0274] In addition, as shown in FIG. 5(B), the light-emitting layer 120 included in the light-emitting unit 108 has a guest material 121 and a host material 122. Note that the guest material 121 is a fluorescent material and will be described below.

[0275] ≪Light-emitting mechanism of the light-emitting layer 120≫ The light-emitting mechanism of the light-emitting layer 120 will be described below.

[0276] Excitons are generated by the recombination of electrons and holes injected from a pair of electrodes (electrode 101 and electrode 102) or a charge generation layer in the light-emitting layer 120. The guest material 1 and holes recombine in the light-emitting layer 120, excitons are generated. The guest material 1 Since the host material 122 is present in a large amount compared to 21, the excitation of excitons forms the excited state of the host material 122. The excited state of the host material 122 is formed.

[0277] Note that an exciton is a pair of carriers (electron and hole). Since an exciton has energy, the material in which the exciton is generated becomes an excited state. When the excited state of the formed host material 122 is a singlet excited state, singlet excitation energy transfers from the S1 level of the host material 122 to the S1 level of the guest material 121, and the singlet excited state of the guest material 121 is formed.

[0278] Since the guest material 121 is a fluorescent material, when the singlet excited state is formed in the guest material 121, the guest material 121 emits light promptly. At this time, in order to obtain high luminous efficiency, it is preferable that the fluorescence quantum yield of the guest material 121 is high. Note that in the guest material 121, when carriers recombine and the generated excited state is a singlet excited state, the same applies. from the S1 level of the host material 122 to the S1 level of the guest material 121, and the singlet excited state of the guest material 121 is formed. The singlet excited state of the guest material 121 is formed.

[0279] Since the guest material 121 is a fluorescent material, when the singlet excited state is formed in the guest material 121, the guest material 121 emits light promptly. At this time, in order to obtain high luminous efficiency, it is preferable that the fluorescence quantum yield of the guest material 121 is high. Note that in the guest material 121, when carriers recombine and the generated excited state is a singlet excited state, the same applies. is the same.

[0280] Next, the case where the triplet excited state of the host material 122 is formed by the recombination of carriers will be described. The energy level correlation of the host material 122 and the guest material 121 in this case is shown in Fig. 5(C). Also, the notations and symbols in Fig. 5(C) are as follows. Since it is preferable that the T1 level of the host material 122 is lower than the T1 level of the guest material 121, Fig. 5(C) shows this case, but the T1 level of the host material 122 may be higher than the T1 level of the guest material 121. The energy level correlation of the host material 122 and the guest material 121 in this case is shown in Fig. 5(C). Also, the notations and symbols in Fig. 5(C) are as follows. Note that since it is preferable that the T1 level of the host material 122 is lower than the T1 level of the guest material 121, Fig. 5(C) shows this case, but the T1 level of the host material 122 may be higher than the T1 level of the guest material 121.

[0281] ·Guest(121): Guest material 121 (fluorescent material)​ ·Host(122): Host material 122 ·S FG : S1 level of guest material 121 (fluorescent material) ·T FG : T1 level of guest material 121 (fluorescent material) ·S FH : S1 level of host material 122 ·T FH : T1 level of host material 122

[0282] As shown in Fig. 5(C), by triplet-triplet annihilation (TTA), the triplet excitons generated by the recombination of carriers interact with each other, transfer excitation energy to each other, and exchange spin angular momentum. As a result, a reaction occurs in which singlet excitons with the energy of the S1 level (S ) of host material 122 are generated (see TTA in Fig. 5(C)). The singlet excitation energy of host material 122 is transferred from S to the S1 level (S ) of guest material 121, which has lower energy than that, and energy transfer occurs (see route E5 in Fig. 5(C)). The singlet excited state of guest material 121 is formed, and guest material 121 emits light. FH ) When the density of triplet excitons in the light-emitting layer 120 is sufficiently high (for example, 1×10 ) or more), the deactivation of single triplet excitons can be ignored, and only the reaction by two adjacent triplet excitons can be considered. FH to the S1 level (S ) of guest material 121, which has lower energy than that, and energy transfer occurs (see route E5 in Fig. 5(C)). The singlet excited state of guest material 121 is formed, and guest material 121 emits light. FG ) (see route E5 in Fig. 5(C)), and the singlet excited state of guest material 121 is formed, and guest material 121 emits light. When carriers recombine in guest material 121 and a triplet excited state is formed, the triplet excited state of guest material 121 thermally deactivates, making it difficult to use for light emission.

[0283] When the density of triplet excitons in the light-emitting layer 120 is sufficiently high (for example, 1×10 -12 cm -3 or higher), the deactivation of single triplet excitons can be ignored, and only the reaction by two adjacent triplet excitons can be considered. excitons can be considered.

[0284] Also, when carriers recombine in guest material 121 and a triplet excited state is formed , the triplet excited state of guest material thermally deactivates, making it difficult to use for light emission. However, when the T1 level (T FH ) of the host material 122 is lower than the T1 level (T ) of the guest material 121, the triplet excitation energy of the guest material 121 can be transferred from the T1 level (T FG ) of the guest material 121 to the T1 level (T ) of the host material 122 (see Route E6 in Fig. 5(C)), and then it is used for TTA. FG ) to the T1 level (T FH ) of the host material 122, and then used for TTA. That is, it is preferable that the host material 122 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 is converted into singlet excitation energy by TTA in the host material 122, and the singlet excitation energy is transferred to the guest material 121, so that fluorescence emission can be extracted. For this purpose, it is preferable that the S1 level (S

[0285] ) of the host material 122 is higher than the S1 level (S ) of the guest material 121. Also, it is preferable that the T1 level (T ) of the host material 122 is lower than the T1 level (T ) of the guest material 121. FH ) of the host material 122 is higher than the S1 level (S FG ) of the guest material 121. Also, it is preferable that the T1 level (T ) of the host material 122 is lower than the T1 level (T FH ) of the guest material 121. FG ) is lower than that of the guest material 121. This is preferable.

[0286] In particular, when the T1 level (T FG ) of the guest material 121 is lower than the T1 level (T ) of the host material 122, the weight ratio of the host material 122 to the guest material 121 is preferably such that the weight ratio of the guest material 121 is lower. Specifically, when the host material 122 is set to 1, the weight ratio of the guest material 121 is preferably greater than 0 and not more than 0.05. By doing so, FH ) of the host material 122, the weight ratio of the host material 122 to the guest material 121 is preferably such that the weight ratio of the guest material 121 is lower. Specifically, when the host material 122 is set to 1, the weight ratio of the guest material 121 is preferably greater than 0 and not more than 0.05. it is preferable that the weight ratio of the guest material 121 is lower. Specifically, when the host material 122 is set to 1, the weight ratio of the guest material 121 is preferably greater than 0 and not more than 0.05. That is, when the host material 122 is set to 1, the weight ratio of the guest material 121 is preferably greater than 0 and not more than 0.05. By doing so, the probability of carrier recombination in the guest material 121 can be reduced. Also, the probability of energy transfer from the T1 level (T FH ) of the host material 122 to the T1 level (T FG ) of the guest material 121 can be reduced.

[0287] Note that the host material 122 may be composed of a single compound or may be composed of a plurality of compounds.

[0288] Also, when the guest materials of the light-emitting unit 106 and the light-emitting unit 108 have different emission colors, it is preferable that the emission from the light-emitting layer 120 has an emission peak on the shorter wavelength side than the 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 emission, a light-emitting device with small luminance degradation can be provided.

[0289] <Configuration Example 2 of Light-Emitting Device> FIG. 6(A) is a cross-sectional schematic view of the light-emitting device 252.

[0290] The light-emitting device 252 shown in FIG. 6(A) has a plurality of light-emitting units (the light-emitting units 106 and 110 in FIG. 6(A)) between a pair of electrodes (electrodes 101 and 102), similar to the light-emitting device 250 shown above. At least one light-emitting unit has a configuration similar to that of the EL layer 100. Note that the light-emitting unit 106 and the light-emitting unit 110 may have the same configuration or different configurations.

[0291] Also, in the light-emitting device 252 shown in FIG. 6(A), the light-emitting unit 106 and the light-emitting unit ​​​110 are stacked, and a charge generation layer 115 is provided between the light-emitting unit 106 and the light-emitting unit 110. For example, it is preferable to use the EL layer 100 for the light-emitting unit 106.

[0292] Further, the light-emitting element 252 has a light-emitting layer 140 and a light-emitting layer 170. The light-emitting unit 106 has, in addition to the light-emitting layer 170, a hole injection layer 111, a hole transport layer 112, an electron transport layer 113, and an electron injection layer 114. The light-emitting unit 110 has, in addition to the light-emitting layer 140, a hole injection layer 116, a hole transport layer 117, an electron transport layer 118, and an electron injection layer 119.

[0293] Note that by applying the configuration shown in Embodiment 1 to at least one of the plurality of units, a light-emitting element with high luminous efficiency can be provided.

[0294] Further, it is preferable that the light-emitting layer of the light-emitting unit 110 has a phosphorescent material. That is, the light-emitting layer 140 of the light-emitting unit 110 has a phosphorescent material, and the light-emitting layer 170 of the light-emitting unit 106 preferably has the configuration of the light-emitting layer 130 or the light-emitting layer 135 shown in Embodiment 1. A configuration example of the light-emitting element 252 in this case will be described below.

[0295] The light-emitting layer 140 of the light-emitting unit 110 has a guest material 141 and a host material 142 as shown in Fig. 6(B). The host material 142 has an organic compound 142_1 and an organic compound 142_2. The guest material 141 included in the light-emitting layer 140 will be described below as a phosphorescent material.

[0296] ≪Light-emitting mechanism of the light-emitting layer 140≫ ​​​​​​​​​​​​​Next, the light-emitting mechanism of the light-emitting layer 140 will be described below.

[0297] The organic compound 142_1 and the organic compound 142_2 included in the light-emitting layer 140 form an exciplex. to form.

[0298] The combination of the organic compound 142_1 and the organic compound 142_2 may be any combination capable of forming an exciplex with each other, but it is more preferable that one is a compound having hole-transporting properties and the other is a compound having electron-transporting properties. and the other is a compound having electron-transporting properties.

[0299] The correlation of the energy levels among the organic compound 142_1, the organic compound 142_2, and the guest material 141 in the light-emitting layer 140 is shown in FIG. 6(C). The notations and symbols in FIG. 6(C) are as follows. are as follows. ·Guest(141): Guest material 141 (phosphorescent material) ·Host(142_1): Organic compound 142_1 (host material) ·Host(142_2): Organic compound 142_2 (host material) ·T PG : T1 level of the guest material 141 (phosphorescent material) ·S PH1 : S1 level of the organic compound 142_1 (host material) ·T PH1 : T1 level of the organic compound 142_1 (host material) ·S PH2 : S1 level of the organic compound 142_2 (host material) ·T PH2 : T1 level of the organic compound 142_2 (host material) ·S PE : S1 level of the exciplex ·T PE : T1 level of the exciplex

[0300] The organic compound 142_1 and the organic compound 142_2 form an exciplex, and the S of the exciplex 1 level (S PE ) and T1 level (T PE ) are adjacent energy levels (Figure 6( C) See route E7).

[0301] One of the organic compounds 142_1 and 142_2 receives a hole and the other receives an electron. Alternatively, when one of the two is excited, it quickly forms an exciplex. Therefore, the exciplex in the light-emitting layer 140 Most of the excited molecules exist as exciplexes. The excited energy levels of exciplexes (S PE Also is T PE ) is a host material (organic compound 142_1 and organic compound 142_2) that forms an exciplex. 42_2) S1 level (S PH1 and S PH2 ) and therefore has a lower excitation energy This allows the formation of an excited state in the host material 142. The driving voltage of the element can be reduced.

[0302] And the (S PE ) and (T PE ) and the energy of the guest material 141 (phosphorescent material) to the T1 level, and light emission is obtained (see routes E8 and E9 in Figure 6(C)). see).

[0303] In addition, the T1 level of the exciplex (T PE ) is the T1 level (T PG )twist By doing so, the singlet excitation energy and and triplet excitation energy to the S1 level (S PE ) and T1 level (T PE )mosquito The T1 level (T PG) can transfer energy thereto.

[0304] Also, in order to efficiently transfer the excitation energy from the exciplex to the guest material 141 , the T1 level (T PE ) of the exciplex is preferably equal to or lower than the T1 levels (T PH1 and T PH2 ) of each organic compound (organic compound 14 2_1 and organic compound 142_2) that forms the exciplex. This makes it difficult for the triplet excitation energy of the exciplex to be quenched by each organic compound (organic compound 142_1 and organic compound 142_2), and energy transfer efficiently occurs from the exciplex to the guest material 141.

[0305] Also, in order for organic compound 142_1 and organic compound 142_2 to efficiently form an exciplex, it is preferable that the HOMO level of one of organic compound 142_1 and organic compound 142_2 is higher than the HOMO level of the other, and the LUMO level of one is higher than the LUMO level of the other. For example, when organic compound 142_1 has hole-transporting properties and organic compound 142_2 has electron-transporting properties, it is preferable that the HOMO level of organic compound 142_1 is higher than the HOMO level of organic compound 142_2, and it is preferable that the LUMO level of organic compound 142_1 is higher than the LUMO level of organic compound 142_2. Alternatively, when organic compound 142_ 2 has hole-transporting properties and organic compound 142_1 has electron-transporting properties, it is preferable that the HOMO level of organic compound 1 42_2 is higher than the HOMO level of organic compound 142_1 , and it is preferable that the LUMO level of organic compound 142_2 is higher than the LUMO level of organic compound 142_1 . Specifically, the HOMO level of organic compound 142_1 and organic compound 142 The energy difference from the HOMO level of _2 is preferably 0.05 eV or more, more preferably 0.1 eV or more, and still more preferably 0.2 eV or more. Also, the energy difference between the LUMO level of organic compound 142_1 and the LUMO level of organic compound 142_2 is preferably 0.05 eV or more, more preferably 0.1 eV or more, and still more preferably 0.2 eV or more.

[0306] In addition, when the combination of organic compound 142_1 and organic compound 142_2 is a combination of a compound having hole transportability and a compound having electron transportability, the carrier balance can be easily controlled by the mixing ratio. Specifically, the range of compound having hole transportability: compound having electron transportability = 1:9 to 9:1 (weight ratio) is preferable. Also, since the carrier balance can be easily controlled by having this configuration, the control of the carrier recombination region can also be easily performed.

[0307] The mechanism of the energy transfer process between the host material 142 (excimer) and the guest material 141 can be explained by two mechanisms, the Förster mechanism (dipole-dipole interaction) and the Dexter mechanism (electron exchange interaction), similar to Embodiment 1. For the Förster mechanism and the Dexter mechanism, refer to Embodiment 1.

[0308] Therefore, in order to facilitate the energy transfer from the singlet excited state of the host material (excimer) to the triplet excited state of the guest material 141, the emission spectrum of the excimer and the ​​​​​​​​​It is preferable that the absorption band appearing on the longest wavelength side (low energy side) of the host material 141 overlaps with that of the guest material 141. By doing so, the generation efficiency of the triplet excited state of the guest material 141 can be increased.

[0309] By configuring the light emitting layer 140 as described above, it becomes possible to efficiently obtain light emission from the guest material 141 (phosphorescent material ) of the light emitting layer 140.

[0310] In addition, the processes of Routes E7 to 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 141. In this case, it is not always necessary for the reverse intersystem crossing efficiency from T to S to be high, nor is it necessary for the light emission quantum yield from S PE to be high. Therefore, a wide range of materials can be selected. PE PE

[0311] Also, it is preferable that the light emission from the light emitting layer 170 has a peak of light emission on the shorter wavelength side than the light emission from the light emitting layer 140. A light emitting device using a phosphorescent material that emits short wavelength light tends to have rapid luminance degradation. Therefore, by making the short wavelength light emission fluorescence, a light emitting device with small luminance degradation can be provided.

[0312] In addition, in each of the above configurations, the emission colors exhibited by the guest materials used in the light emitting unit 106 and the light emitting unit 108, or the light emitting unit 106 and the light emitting unit 110, may be the same as or different from each other. The emission colors exhibited by the light emitting unit 106 and the light emitting unit 108 ​​​​​​​​or the light-emitting units 106 and 110, the light-emitting elements 250 and 252 are preferably light-emitting elements that exhibit high light-emitting luminance at a low current value when having a guest material having a function of emitting light of the same color as each other. Also, when having a guest material having a function of emitting light of different colors from each other in the light-emitting unit 106 and the light-emitting unit 108, or the light-emitting unit 106 and the light-emitting unit 110, the light-emitting elements 250 and 252 are preferably light-emitting elements that exhibit multicolor light emission. In this case, either one or both of the light-emitting layer 120 and the light-emitting layer 170, or either one or both of the light-emitting layer 140 and the light-emitting layer 170, by using a plurality of light-emitting materials having different emission wavelengths, the emission spectra exhibited by the light-emitting elements 250 and 252 are synthesized with light having different emission peaks, so that the emission spectrum has at least two maxima. When having a guest material having a function of emitting light of the same color as each other, the light-emitting elements 250 and 252 are preferably light-emitting elements that exhibit high light-emitting luminance at a low current value. Also, when having a guest material having a function of emitting light of different colors from each other in the light-emitting unit 106 and the light-emitting unit 108, or the light-emitting unit 106 and the light-emitting unit 110, the light-emitting elements 250 and 252 are preferably light-emitting elements that exhibit multicolor light emission. In this case, either one or both of the light-emitting layer 120 and the light-emitting layer 170, or either one or both of the light-emitting layer 140 and the light-emitting layer 170, by using a plurality of light-emitting materials having different emission wavelengths, the emission spectra exhibited by the light-emitting elements 250 and 252 are synthesized with light having different emission peaks, so that the emission spectrum has at least two maxima. When having a guest material having a function of emitting light of different colors from each other in the light-emitting unit 106 and the light-emitting unit 108, or the light-emitting unit 106 and the light-emitting unit 110, the light-emitting elements 250 and 252 are preferably light-emitting elements that exhibit multicolor light emission. In this case, either one or both of the light-emitting layer 120 and the light-emitting layer 170, or either one or both of the light-emitting layer 140 and the light-emitting layer 170, by using a plurality of light-emitting materials having different emission wavelengths, the emission spectra exhibited by the light-emitting elements 250 and 252 are synthesized with light having different emission peaks, so that the emission spectrum has at least two maxima. In this case, either one or both of the light-emitting layer 120 and the light-emitting layer 170, or either one or both of the light-emitting layer 140 and the light-emitting layer 170, by using a plurality of light-emitting materials having different emission wavelengths, the emission spectra exhibited by the light-emitting elements 250 and 252 are synthesized with light having different emission peaks, so that the emission spectrum has at least two maxima. In this case, either one or both of the light-emitting layer 120 and the light-emitting layer 170, or either one or both of the light-emitting layer 140 and the light-emitting layer 170, by using a plurality of light-emitting materials having different emission wavelengths, the emission spectra exhibited by the light-emitting elements 250 and 252 are synthesized with light having different emission peaks, so that the emission spectrum has at least two maxima. In this case, either one or both of the light-emitting layer 120 and the light-emitting layer 170, or either one or both of the light-emitting layer 140 and the light-emitting layer 170, by using a plurality of light-emitting materials having different emission wavelengths, the emission spectra exhibited by the light-emitting elements 250 and 252 are synthesized with light having different emission peaks, so that the emission spectrum has at least two maxima. In this case, either one or both of the light-emitting layer 120 and the light-emitting layer 170, or either one or both of the light-emitting layer 140 and the light-emitting layer 170, by using a plurality of light-emitting materials having different emission wavelengths, the emission spectra exhibited by the light-emitting elements 250 and 252 are synthesized with light having different emission peaks, so that the emission spectrum has at least two maxima. In this case, either one or both of the light-emitting layer 120 and the light-emitting layer 170, or either one or both of the light-emitting layer 140 and the light-emitting layer 170, by using a plurality of light-emitting materials having different emission wavelengths, the emission spectra exhibited by the light-emitting elements 250 and 252 are synthesized with light having different emission peaks, so that the emission spectrum has at least two maxima.

[0313] The above configuration is also suitable for obtaining white light emission. By making the light of the light-emitting layer 120 and the light-emitting layer 170, or the light-emitting layer 140 and the light-emitting layer 170, be in a complementary color relationship with each other, white light emission can be obtained. In particular, it is preferable to select a guest material so as to obtain white light emission with high color rendering properties, or light emission having at least red, green, and blue. The above configuration is also suitable for obtaining white light emission. By making the light of the light-emitting layer 120 and the light-emitting layer 170, or the light-emitting layer 140 and the light-emitting layer 170, be in a complementary color relationship with each other, white light emission can be obtained. In particular, it is preferable to select a guest material so as to obtain white light emission with high color rendering properties, or light emission having at least red, green, and blue. In particular, it is preferable to select a guest material so as to obtain white light emission with high color rendering properties, or light emission having at least red, green, and blue.

[0314] Also, at least one of the light-emitting layer 120, the light-emitting layer 140, 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, at least one of the light-emitting layer 120, the light-emitting layer 140, and the light-emitting layer 170 can also be configured with two or more layers. For example, the first light-emitting layer and the second light-emitting layer on the hole transport layer side Also, at least one of the light-emitting layer 120, the light-emitting layer 140, 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, at least one of the light-emitting layer 120, the light-emitting layer 140, and the light-emitting layer 170 can also be configured with two or more layers. That is, at least one of the light-emitting layer 120, the light-emitting layer 140, and the light-emitting layer 170 can also be configured with two or more layers. When stacking in order from to form a light-emitting layer, a material having hole-transporting properties is used as the host material of the first light-emitting layer, and a material having electron-transporting 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 the function of emitting light of the same color, or materials having the function of emitting light of different colors. By having a configuration having a plurality of light-emitting materials having the function of emitting light of different colors, it is also possible to obtain white light emission with high color rendering consisting of three primary colors or four or more light-emitting colors.

[0315] <Examples of materials that can be used for the light-emitting layer> Next, materials that can be used for the light-emitting layer 120, the light-emitting layer 140, and the light-emitting layer 170 will be described below.

[0316] ≪Materials that can be used for the light-emitting layer 120≫ In the light-emitting layer 120, the host material 122 is present in the largest amount by weight, and the guest material 121 (fluorescent material) is dispersed in the host material 122. The S1 level of the host material 122 is higher than the S1 level of the guest material 121 (fluorescent material), and the T1 level of the host material 122 is preferably lower than the T1 level of the guest material 121 (fluorescent material).

[0317] In the light-emitting layer 120, the guest material 121 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. ​​

[0318] 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-dia mine (abbreviation: 1,6tBu-FLPAPrn), N,N'-diphenyl-N,N'-bis [4-(9-phenyl-9H-fluorene-9-yl)phenyl]-3,8-dicyclohe xylpyrene-1,6-diamine (abbreviation: ch-1,6FLPAPrn), N,N'-b is[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenylstilbe ne-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 (abbre Name: 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: DPAB PA), N,9 - diphenyl - N - [4 - (9,10 - diphenyl - 2 - anthryl)ph enyl]-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’’’ - octaphenyldibenz[g,p]chrysene - 2,7,10 ,15 - tetraamine (Abbreviation: DBC1), coumarin 30, N - (9,10 - diphenyl -2 - anthryl)-N,9 - diphenyl - 9H - carbazole - 3 - amine (Abbreviation: 2 PCAPA), N - [9,10 - bis(1,1’ - biphenyl - 2 - yl)-2 - anth ryl]-N,9 - diphenyl - 9H - carbazole - 3 - amine (Abbreviation: 2PCABPh A), 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’ - bip enyl - 2 - yl)-N - [4 - (9H - carbazol - 9 - yl)phenyl]-N - f 2-YGABPhA (2-Enylanthracen-2-amine), N,N,9-Triphenylanthracen-9-amine (DPhAPhA), Coumarin 6, Coumarin 545T N,N’-Diphenylquinacridone (DPQd), Rubrene, 2,8-Di-tert-butyl-5,11-bis(4-tert-butylphenyl)-6,12-diphenyltetracene (TBRb) Nile Red, 5,12-Bis(1,1’-biphenyl-4-yl)-6,11-diphenyltetracene (BPT), 2-(2-{2- [4-(Dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyran-4-ylidene)propanedinitrile (DCM1) 2-{2-Methyl-6-[2-(2,3,6,7-Tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (DCM2), N,N,N ’,N’-Tetrakis(4-methylphenyl)tetracene-5,11-diamine (p-mPhTD), 7,14-Diphenyl-N,N,N’,N’-tetrakis(4-methyl phenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (p-mPhAFD), 2-{2-Isopropyl-6-[2-(1,1,7,7-Tetramethyl -2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (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 ​​​​​​​​-4H-Pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB), 2-(2, 6-bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4-yl idene)propanedinitrile (abbreviation: BisDCM), 2-{2,6-bis[2-(8- methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H -benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}pro panedinitrile (abbreviation: BisDCJTM), 5,10,15,20-tetraphenyl bisbenzo[5,6]indeno[1,2,3-cd:1’,2’,3’-lm]perylene and the like can be mentioned.

[0319] Also, in the light-emitting layer 120, the materials that can be used for the host material 122 are 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]benz 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-benzimidazole (abbreviation: TPBI), bathophenanthroline (abbreviation: BPhen), bathocuproin (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’-bifluorene-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 are included. 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]phenyl}-9H-carbazole-3-amine (abbreviation: PCAPBA), N,9-diphenyl -N-(9,10-diphenyl-2-anthryl)-9H-carbazole-3-amine (abbreviation: 2PCAPA), 6,12-dimethoxy-5,11-diphenylchrysene, N, N,N’,N’,N’’,N’’,N’’’,N’’’-octaphenyldibenzo[g, p]chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), 9-[4-(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’-(stil bene-3,3’-diyl)diphenanthrene (abbreviation: DPNS), 9,9’-(stilbene -4,4’-diyl)diphenanthrene (abbreviation: DPNS2), 1,3,5-tri(1 -pyrenyl)benzene (abbreviation: TPB3), etc. can be mentioned. Also, from these and known substances, substances having an energy gap larger than the energy gap of the guest material 121 above may be selected and used one or more kinds. In addition, the light-emitting layer 120 can also be composed of two or more layers. For example, the first layer...

[0320] Furthermore, the light-emitting layer 120 can also be configured with two or more layers. For example, the first When the 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.

[0321] Also, in the light-emitting layer 120, the host material 122 may be composed of a single 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 122 and the guest material 121.

[0322] ≪Materials that can be used for the light-emitting layer 140≫ In the light-emitting layer 140, the host material 142 is present in the largest amount by weight, and the guest material 141 (phosphorescent material) is dispersed in the host material 142. The T1 level of the host material 142 of the light-emitting layer 140 ( organic compound 142_1 and organic compound 142_2) is preferably higher than the T 1 level of the guest material 141.

[0323] Examples of the organic compound 142_1 include zinc and aluminum-based metal complexes, as well as oxadiazole derivatives, triazole derivatives, benzimidazole derivatives, quinoxaline derivatives, dibe nzoquinoxaline derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, pyrimidi ne derivatives, triazine derivatives, pyridine derivatives, bipyridine derivatives, phenanthroline deriva tives, etc. Other examples include aromatic amines and carbazole derivatives. Specifically, the electron transport material and the hole transport material shown in Embodiment 1 can be used.

[0324] Examples of the organic compound 142_2 include combinations that can form an exciplex with the organic compound 142_1 Specifically, the electron transport material and the hole transport material shown in Embodiment 1 are preferably used in combination. In this case, the organic compound 142_1 and the organic compound 142_2 can be used. The emission peak of the formed exciplex is the triplet MLCT( Metal to Ligand Charge Transfer (MLC) transition absorption band, Specifically, organic compound 142_1 and organic compound 142_2 are selected so that they overlap with the absorption band on the longest wavelength side. It is preferable to select the material 142_2 and the guest material 141 (phosphorescent material). As a result, a light-emitting element with dramatically improved luminous efficiency can be obtained. In addition, when a thermally activated delayed fluorescent material is used, the absorption band on the longest wavelength side is the absorption band of the singlet state. Preferably it is a band.

[0325] As the guest material 141 (phosphorescent material), an organic compound of iridium, rhodium, or platinum is used. Metal complexes, or metal complexes, among which organic iridium complexes, e.g., iridium The orthometalated complex is preferably a 4H-triazole. Ligand, 1H-triazole ligand, imidazole ligand, pyridine ligand, pyrimidine The metal complexes include a pyrazine ligand, an isoquinoline ligand, and the like. Examples of the platinum complex include a platinum complex having a porphyrin ligand. The materials exemplified as the guest material 131 shown in 1 can be used.

[0326] The light-emitting material contained in the light-emitting layer 140 is a material capable of converting triplet excitation energy into light. The material capable of converting triplet excitation energy into luminescence is a phosphorescent material. In addition, thermally activated delayed fluorescence materials are included. Therefore, regarding the part described as a phosphorescent material, it may be read as a thermally activated delayed fluorescence material.

[0327] Also, a material that exhibits thermally activated delayed fluorescence may be a material that can generate a singlet excited state from a triplet excited state by reverse intersystem crossing alone, or may be composed of a plurality of materials that form an exciplex (also referred to as an exciplex or Exciplex). When the thermally activated delayed fluorescence material is composed of one type of material, specifically, the thermally activated delayed fluorescence material shown in Embodiment 1 can be used.

[0328] 1 can be used. 1 can be used.

[0329] When using a thermally activated delayed fluorescence material as a host material, it is preferable to use a combination of two types of compounds that form an exciplex. In this case, it is particularly preferable to use a compound that easily receives electrons and a compound that easily receives holes, which is the combination that forms the exciplex shown above. When using a thermally activated delayed fluorescence material as a host material, it is preferable to use a combination of two types of compounds that form an exciplex. In this case, it is particularly preferable to use a compound that easily receives electrons and a compound that easily receives holes, which is the combination that forms the exciplex shown above. When using a thermally activated delayed fluorescence material as a host material, it is preferable to use a combination of two types of compounds that form an exciplex. In this case, it is particularly preferable to use a compound that easily receives electrons and a compound that easily receives holes, which is the combination that forms the exciplex shown above. When using a thermally activated delayed fluorescence material as a host material, it is preferable to use a combination of two types of compounds that form an exciplex. In this case, it is particularly preferable to use a compound that easily receives electrons and a compound that easily receives holes, which is the combination that forms the exciplex shown above.

[0330] ≪Materials that can be used for the light-emitting layer 170≫ As materials that can be used for the light-emitting layer 170, the materials that can be used for the light-emitting layer shown in the previous Embodiment 1 may be adopted, and by doing so, a light-emitting device with high luminous efficiency can be manufactured. manufactured.

[0331] In addition, there is no limitation on the emission color of the light-emitting materials included in the light-emitting layer 120, the light-emitting layer 140, 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 in a complementary color relationship, the light-emitting element element The child can give white light. Considering the reliability of the light-emitting element, included in the light-emitting layer 120 The emission peak wavelength of the light-emitting material contained therein is shorter than that of the light-emitting material contained in the light-emitting layer 170. This is preferable.

[0332] Note that the light-emitting unit 106, the light-emitting unit 108, the light-emitting unit 110, and the charge generation layer 115 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, etc. This can be formed by the method of.

[0333] As described above, the configuration shown in this embodiment can be used in appropriate combination with the configuration shown in other embodiments. This can be used.

[0334] (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. 7 to 10. This will be described below with reference to FIGS. 7 to 10.

[0335] <Configuration Example 1 of Light-Emitting Element> FIGS. 7(A) and 7(B) are cross-sectional views showing a light-emitting element according to an aspect of the present invention. Note that in FIGS. 7(A) and 7(B), portions having the same functions as those denoted by the reference numerals shown in FIG. 1(A) may be denoted by 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.

[0336] The light-emitting elements 260a and 260b shown in FIGS. 7(A) and 7(B) may be bottom emission type light-emitting elements that extract light on the substrate 200 side, or may be top emission type light-emitting elements that extract light in a direction opposite to the substrate 200. This is also good. Note that one aspect of the present invention is not limited to this, and the light emitted by the light-emitting element is above the substrate 200 and also It may also be a dual-emission type light-emitting element that emits light to both the upper and lower sides. .

[0337] When the light-emitting element 260a and the light-emitting element 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 element 260a and the light-emitting element 260b are of the top emission type, the electrode 101 preferably has a function of reflecting light. Also, the electrode 102 preferably has a function of transmitting light.

[0338] The light-emitting element 260a and the light-emitting element 260b have the electrode 101 and the electrode 102 on the substrate 200. Also, between the electrode 101 and the electrode 102, there are the light-emitting layer 123B, the light-emitting layer 123 G, and the light-emitting layer 123R. Also, there are the hole injection layer 111, the hole transport layer 112, the electron transport layer 118, and the electron injection layer 119.

[0339] Also, the light-emitting element 260b has, as a part of the configuration of the electrode 101, the conductive layer 101a, the conductive layer 101b on the conductive layer 101a, and the conductive layer 101c under the conductive layer 101a. That is, the light-emitting element 260b has a configuration of the electrode 101 in which the conductive layer 101a is sandwiched between the conductive layer 101b and the conductive layer 101c.

[0340] In the light-emitting element 260b, the conductive layer 101b and the conductive layer 101c may be formed of different materials or the same material. When the electrode 101 has a configuration in which the conductive layer 101a is sandwiched between the same conductive electric materials, in the etching process in the formation process of the electrode 101 This is preferable because it facilitates pattern formation.

[0341] In the light-emitting element 260b, in the conductive layer 101b or the conductive layer 101c, it may be configured to have only one of them.

[0342] Note that the conductive layers 101a, 101b, and 101c included in the electrode 101 can use the same configuration and material as the electrode 101 or the electrode 102 shown in Embodiment Form 1 respectively. be possible.

[0343] In FIGS. 7(A) and 7(B), a partition wall 145 is provided between the regions 221B, region 221G, and region 221R, which are sandwiched between the electrode 101 and the electrode 102. The partition wall 145 has insulating properties. The partition wall 145 covers the end of the electrode 101 and has an opening overlapping 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.

[0344] Note that the light-emitting layer 123B and the light-emitting layer 123G may have an overlapping region 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 an overlapping region with each other in a region overlapping with the partition wall 145. Alternatively, the light-emitting layer 123R and the light-emitting layer 123B may have an overlapping region with each other in a region overlapping with the partition wall 145.

[0345] 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 oxynitride, silicon nitride, aluminum oxide, aluminum nitride, etc. Examples of the organic material include etc.​​​​ For example, photosensitive resin materials such as acrylic resin or polyimide resin can be mentioned.

[0346] The silicon oxynitride film refers to a film having a higher oxygen content than nitrogen in its composition. Preferably, oxygen is 55 atomic % or more and 65 atomic % or less, nitrogen is 1 atomic % or more and 20 atomic % or less, silicon is 25 atomic % or more and 35 atomic % or less, and hydrogen is 0.1 atomic % or more and 10 atomic % or less. The silicon nitride oxide film refers to a film having a higher nitrogen content than oxygen in its composition. Preferably, nitrogen is 55 atomic % or more and 65 atomic % or less, oxygen is 1 atomic % or more and 20 atomic % or less, silicon is 25 atomic % or more and 35 atomic % or less, and hydrogen is 0.1 atomic % or more and 10 atomic % or less.

[0347] In addition, the light-emitting layer 123R, the light-emitting layer 123G, and the light-emitting layer 123B preferably have light-emitting materials having functions of exhibiting different colors. For example, by having a light-emitting material having a function of the light-emitting layer 123R exhibiting red, the region 221R exhibits red light emission. By having a light-emitting material having a function of the light-emitting layer 123G exhibiting green, the region 221G exhibits green light emission. By having a light-emitting material having a function of the light-emitting layer 123B exhibiting blue, the region 221 B exhibits blue light emission. By using the light-emitting element 260a or the light-emitting element 26 0b having such a configuration for a pixel of a display device, a display device capable of full-color display can be manufactured. In addition, the film thicknesses of the respective light-emitting layers may be the same or different. Moreover, any one or more of the light-emitting layer 123B, the light-emitting layer 123G, and the light-emitting layer 123R By using it for a pixel of a display device, a display device capable of full-color display can be manufactured. Moreover, the film thicknesses of the respective light-emitting layers may be the same or different.

[0348] In addition, any one or more of the light-emitting layer 123B, the light-emitting layer 123G, and the light-emitting layer 123R ​​The light-emitting layer is at least one of the light-emitting layer 130 and the light-emitting layer 135 shown in the first embodiment. It is preferable that the light-emitting element has one of the above structures. It is possible.

[0349] In addition, any one or more of the light-emitting layer 123B, the light-emitting layer 123G, and the light-emitting layer 123R The light-emitting layer may have a structure in which two or more layers are laminated.

[0350] As described above, at least one light-emitting layer has the light-emitting properties shown in the first and second embodiments. The light emitting element 260a or the light emitting element 260b having the light emitting layer is used in a display device. By using the organic EL element in the pixel of a display device, a display device with high luminous efficiency can be manufactured. A display device having the light-emitting element 260a or the light-emitting element 260b can reduce power consumption. can be done.

[0351] In addition, if an optical element (for example, a color filter, By providing a polarizing plate, an anti-reflection film, etc., the color purity of the light emitting element 260a and the light emitting element 260b can be improved. Therefore, the light emitting element 260a or the light emitting element 260b is effectively used. Alternatively, the color purity of the display device can be improved. Therefore, the light emitting element 260a or the light emitting element 260b can be prevented from reflecting external light. The contrast ratio of a display device having the element 260b can be increased.

[0352] Other configurations of the light emitting element 260a and the light emitting element 260b are the same as those in the embodiment. The structures of the light-emitting elements in Embodiments 1 and 2 may be referred to.

[0353] <Configuration example 2 of light-emitting element> Next, a configuration example different from the light-emitting element shown in FIGS. 7(A) and 7(B) will be described with reference to FIGS. 8(A) and 8(B). This will be described below using FIGS. 8(A) and 8(B).

[0354] FIGS. 8(A) and 8(B) are cross-sectional views showing a light-emitting element according to an aspect of the present invention. In FIGS. 8(A )(B), portions having the same functions as those denoted by the same reference numerals in FIGS. 7(A) and 7(B) may be given 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.

[0355] FIGS. 8(A) and 8(B) show a configuration example of a light-emitting element having a light-emitting layer between a pair of electrodes. The light-emitting element 262a shown in FIG. 8 (A) is a top emission type light-emitting element that emits light in a direction opposite to the substrate 200, and the light-emitting element 262b shown in FIG. 8(B) is a bottom emission type light-emitting element that emits light toward the substrate 200 side. However, an 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 an electrode 103, and an electrode 104 on the substrate 200. Also, between the electrode 101 and the electrode 102, and

[0356] 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. a hole transport layer 117, an electron transport layer 11, and an electron injection layer 119. And an electron injection layer 119.

[0357] The electrode 101 includes a conductive layer 101a and a conductive layer 101b that is in contact with the conductive layer 101a. The electrode 103 includes a conductive layer 103a and a conductive layer 103b on and in contact with the conductive layer 103a. The electrode 104 has a conductive layer 104a and a conductive layer 103b on the conductive layer 104a. and an insulating layer 104b.

[0358] The light emitting element 262a shown in FIG. 8(A) and the light emitting element 262b shown in FIG. 8(B) are The area 222B sandwiched between the electrode 101 and the electrode 102, and the area 222B san...

Claims

1. Between a pair of electrodes, having a hole injection layer and a light-emitting layer, The hole injection layer has a material exhibiting electron-accepting properties, The light-emitting layer has a phosphorescent material and a host material, The host material has a π-electron-deficient heteroaromatic ring skeleton, The host material has at least one of a π-electron-excessive heteroaromatic ring skeleton or an aromatic amine skeleton, The LUMO level of the phosphorescent material is lower than the LUMO level of the host material, The energy difference between the LUMO level and the HOMO level of the phosphorescent material is larger than the energy difference between the LUMO level and the HOMO level of the host material, A light-emitting device in which the energy difference between the LUMO level of the phosphorescent material and the HOMO level of the host material is equal to or greater than the transition energy calculated from the absorption edge in the absorption spectrum of the phosphorescent material.

2. Between a pair of electrodes, having a hole injection layer and a light-emitting layer, The hole injection layer has a material exhibiting electron-accepting properties, The light-emitting layer has a phosphorescent material and a host material, The host material has a π-electron-deficient heteroaromatic ring skeleton, The host material has at least one of a π-electron-excessive heteroaromatic ring skeleton or an aromatic amine skeleton, The LUMO level of the phosphorescent material is lower than the LUMO level of the host material, The energy difference between the LUMO level and the HOMO level of the phosphorescent material is larger than the energy difference between the LUMO level and the HOMO level of the host material, A light-emitting device in which the energy difference between the LUMO level of the phosphorescent material and the HOMO level of the host material is equal to or greater than the energy of the light emission exhibited by the phosphorescent material.

3. In Claim 2, The energy of the light emission exhibited by the phosphorescent material is derived from the light emission peak wavelength on the shortest wavelength side among the light emission peaks (maximum value or shoulder) of the light emission spectrum. A light-emitting device.

4. In Claim 2, The energy of the light emission exhibited by the phosphorescent material is derived from the rising wavelength on the shortest wavelength side of the light emission spectrum. A light-emitting device.

5. In any one of Claims 1 to 4, The energy difference between the LUMO level and the HOMO level of the phosphorescent material is 0.4 eV or more greater than the transition energy calculated from the absorption edge in the absorption spectrum of the phosphorescent material. A light-emitting device.

6. In any one of Claims 1 to 4, The energy difference between the LUMO level and the HOMO level of the phosphorescent material is greater than or equal to 0.4 eV than the energy of the light emission exhibited by the phosphorescent material, a light-emitting device.

7. In any one of Claims 1 to 6, The host material has a function of donating excitation energy to the phosphorescent material, a light-emitting device.

8. In any one of Claims 1 to 7, The phosphorescent material has any one of ruthenium, rhodium, palladium, osmium, iridium, and platinum, a light-emitting device.

9. In any one of Claims 1 to 8, The phosphorescent material exhibits light emission, a light-emitting device.

10. In any one of Claims 1 to 9, The host material has a difference between the singlet excitation energy level and the triplet excitation energy level greater than 0 eV and less than or equal to 0.2 eV, a light-emitting device.

11. In any one of Claims 1 to 10, The host material has a function of exhibiting thermally activated delayed fluorescence at room temperature, a light-emitting device.

12. In any one of Claims 1 to 11, The material exhibiting electron acceptability is an organic compound having a halogen group or a cyano group, a light-emitting device.

13. In any one of Claims 1 to 12, The values of the HOMO level and the LUMO level are values calculated from measurements by cyclic voltammetry (CV) method, a light-emitting device.

14. A light-emitting device according to any one of Claims 1 to 13, At least one of a color filter or a transistor, A display device having the same.

15. A display device according to Claim 14, At least one of a housing or a touch sensor, An electronic device having the same.

16. A light-emitting device according to any one of Claims 1 to 13, At least one of a housing or a touch sensor, An illumination device having the same.

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