Light-emitting element, display device, electronic device, and lighting device

Abstract

To provide a light emitting element which has high luminous efficiency and is driven by a low voltage.SOLUTION: There is provided a light emitting element having a guest material and a host material. The HOMO level of the guest material is higher than the HOMO 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. The guest material has a function of converting triplet excitation energy into light emission. The energy difference between the LUMO level of the host material and the HOMO level of the guest material is greater than or equal to the energy of light emitted by 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 the present 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, etc. 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 between them, light emission from the luminescent material can be obtained.

[0004] Since the above-mentioned light-emitting element is a self-luminous type, a display device using the light-emitting element has excellent visibility and backlighting. 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 (such as an organic EL device), applying a voltage between a pair of electrodes causes light to be emitted from the cathode. Electrons are injected from the anode into the EL layer, and holes are injected from the anode into the EL layer, causing a current to flow. The injected electrons and holes then recombine to excite the light-emitting organic material. The excited light-emitting organic material is then in a luminescent state, and light can be emitted from the excited light-emitting organic material.

[0006] The types of excited states that organic materials can form include singlet excited states (S * ) and triplet excited states state(T * ) emission from the singlet excited state is fluorescence, and emission from the triplet excited state is phosphorescence. The statistical generation ratio of these in a light-emitting element is called S * :T * =1 Therefore, it is more efficient to use a light-emitting element that emits phosphorescence than a light-emitting element that uses a material that emits fluorescence (fluorescent material). Therefore, a light-emitting element using a material that emits light (phosphorescent material) can have higher luminous efficiency. Therefore, a phosphorescent material capable of converting the energy of the triplet excited state into light emission is used. In recent years, light-emitting devices having such properties have been actively developed (see, for example, Patent Document 1).

[0007] The energy required to excite an organic material is determined by the LUMO and HOMO levels of the organic material. The energy difference depends on the energy difference between the excited state and the singlet state. In a light-emitting element using an organic material that emits phosphorescence, the triplet excitation energy is The energy is converted into light emission. Therefore, the singlet excited state and triplet excited state formed by organic materials When the energy difference between the excited state and the excited state is large, the energy required to excite the organic material is The energy difference between the two is the energy of the light emitted. The energy difference between the energy required to excite an organic material and the energy of light emission This affects the element characteristics as an increase in the driving voltage of the light-emitting element. Techniques for reducing pressure are currently being developed (see Patent Document 2).

[0008] In addition, among light-emitting elements using phosphorescent materials, light-emitting elements that emit blue light, However, due to the difficulty in developing stable organic materials with high triplet excitation energy levels, Therefore, there is a need to develop a phosphorescent light-emitting element that has high luminous efficiency and excellent reliability. There is a demand for child development. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2010-182699 A [Patent Document 2] JP 2012-212879 A Summary of the Invention [Problem to be solved by the invention]

[0010] Iridium complexes are known as phosphorescent materials that exhibit high luminous efficiency. As energetic iridium complexes, we have developed a pyridine skeleton or a nitrogen-containing five-membered heterocyclic skeleton. Iridium complexes having a pyridine skeleton or a nitrogen-containing five-membered heterocycle as a ligand are known. The skeleton has a high triplet excitation energy but a low electron-accepting property. The iridium complexes with the ligands have high HOMO and LUMO levels, and are suitable for hole carriers. While ions are easily injected into the material, electron carriers are difficult to inject into the material. In iridium complexes with valence, excitation by direct recombination of carriers is difficult, It is difficult to emit light efficiently.

[0011] Therefore, in one embodiment of the present invention, a light-emitting element having a phosphorescent material has high emission efficiency. Another object of the present invention is to provide a light-emitting element having low power consumption. Another object of the present invention is to provide a light-emitting element having a reduced signal. Another object of the present invention is to provide a light-emitting element with excellent reliability. Another object of the present invention is to provide a novel light-emitting element. Another object of the present invention is to provide a light-emitting device. One of the objectives of the project is to provide a place where

[0012] Note that the above description of the object does not preclude the existence of other objects. It is not necessary to solve all of these problems. Problems other than those mentioned above can be solved by the description of the specification, etc. It is obvious from the description of the specification, etc. that other problems can be extracted. do. [Means for solving the problem]

[0013] One aspect of the present invention is a light-emitting device having a host material that can efficiently excite a phosphorescent material. It is an element.

[0014] Therefore, one embodiment of the present invention is a light-emitting element having a guest material and a host material. Therefore, the HOMO level of the guest material is higher than the HOMO level of the host material. The energy difference between the LUMO and HOMO levels of the host material is The energy difference between the triplet excitation level and the guest material is larger than that of the triplet excitation level, and the guest material converts the triplet excitation energy into light emission. It is a light-emitting element having a function of being able to emit light.

[0015] Another embodiment of the present invention is a light-emitting element including a guest material and a host material. The HOMO level of the guest material is higher than the HOMO level of the host material, and the L The energy difference between the UMO and HOMO levels is the energy difference between the LUMO and HOMO levels of the host material. The energy difference between the triplet excitation and the guest material is larger than the energy difference between the triplet excitation and the guest material, and the guest material converts the triplet excitation energy into light emission. The LUMO level of the host material and the HOMO level of the guest material are The energy difference is the transition energy calculated from the absorption edge in the absorption spectrum of the guest material. It is a light-emitting element with more than 10 ...

[0016] Another embodiment of the present invention is a light-emitting element including a guest material and a host material. The HOMO level of the guest material is higher than the HOMO level of the host material, and the L The energy difference between the UMO and HOMO levels is the energy difference between the LUMO and HOMO levels of the host material. The energy difference between the triplet excitation and the guest material is larger than the energy difference between the triplet excitation and the guest material, and the guest material converts the triplet excitation energy into light emission. The LUMO level of the host material and the HOMO level of the guest material are is equal to or larger than the light emission energy of the guest material.

[0017] In each of the above structures, the energy between the LUMO level and the HOMO level of the guest material is The difference is the transition energy calculated from the absorption edge in the absorption spectrum of the guest material. It is preferable that the LUMO level and the HOMO level of the guest material are larger than 0.4 eV. The energy difference is preferably 0.4 eV or more larger than the light emission energy of the guest material. I wish.

[0018] In each of the above structures, the host material has a singlet excitation energy level and a triplet excitation energy level. It is preferable that the difference between the host energy level and the host material is more than 0 eV and 0.2 eV or less. The material preferably has the function of exhibiting thermally activated delayed fluorescence at room temperature.

[0019] In each of the above structures, the host material has a function of providing excitation energy to the guest material. In addition, the emission spectrum of the host material is preferably such that the emission spectrum of the guest material is It is preferable that the wavelength region overlaps with the absorption band on the lowest energy side in the absorption spectrum of I wish.

[0020] In each of the above structures, the guest material preferably contains iridium. Preferably, the material exhibits luminescence.

[0021] In each of the above structures, the host material has a function of transporting electrons, The host material preferably has a function of transporting holes. The aromatic heterocyclic compound has a π-electron deficient heteroaromatic ring skeleton, and the host material has a π-electron rich heteroaromatic ring skeleton. It is preferable that the compound has at least one of a π-electron deficient heteroaromatic skeleton and an aromatic amine skeleton. The aromatic skeleton has at least one of a diazine skeleton and a triazine skeleton, and is a π-electron-rich type. The heteroaromatic ring skeleton is an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, It is preferable that the aryl group has at least one of a thiophene skeleton, a thiophene skeleton, and a pyrrole skeleton.

[0022] Another embodiment of the present invention is a light-emitting element having any of the above structures, and a color filter or a transistor. Another aspect of the present invention is a display device comprising the The electronic device has a display device and at least one of a housing and a touch sensor. Another aspect of the present invention is a light-emitting element having any of the above structures, and at least one of a housing and a touch sensor. Another embodiment of the present invention is a lighting device having a light-emitting element. In addition, electronic devices having a light-emitting device are also included in the scope of the present invention. An optical device refers to an image display device or a light source (including a lighting device). Also, a light-emitting device Connectors, such as FPC (Flexible Printed Circuit), Module with TCP (Tape Carrier Package) attached, T A module with a printed wiring board at the end of the CP, or a COG (Chip on Glass) This invention also includes modules in which ICs (integrated circuits) are directly mounted using the "on glass" method. This is one aspect. Effect of the Invention

[0023] According to one embodiment of the present invention, a light-emitting element having a phosphorescent material and high emission efficiency can be obtained. According to one embodiment of the present invention, a light-emitting element with reduced power consumption can be provided. According to one embodiment of the present invention, a highly reliable light-emitting element can be provided. According to one embodiment of the present invention, a novel light-emitting element can be provided. According to one embodiment of the present invention, a novel light-emitting device can be provided. Furthermore, according to one embodiment of the present invention, a novel display device can be provided.

[0024] Note that the description of these effects does not preclude the existence of other effects. It is not necessary to have all of these effects. Effects other than these are described in the specification. The disclosure of the specification, drawings, claims, etc. is self-evident, and the disclosure of the specification, drawings, claims, etc. is self-evident. From this, it is possible to extract other effects. [Brief description of the drawings]

[0025] [Figure 1] 1 is a schematic cross-sectional view of a light-emitting element according to one embodiment of the present invention. [Diagram 2] 1A and 1B are schematic diagrams illustrating the correlation between energy levels and the correlation between energy bands in a light-emitting layer of a light-emitting element according to one embodiment of the present invention. [Diagram 3] 1 is a schematic cross-sectional view of a light-emitting element according to one embodiment of the present invention. [Figure 4] 1A and 1B are schematic diagrams illustrating the correlation between energy levels and the correlation between energy bands in a light-emitting layer of a light-emitting element according to one embodiment of the present invention. [Diagram 5] 1A and 1B are a schematic cross-sectional view of a light-emitting element of one embodiment of the present invention and a schematic diagram illustrating the correlation between energy levels of a light-emitting layer. [Figure 6] 1A and 1B are a schematic cross-sectional view of a light-emitting element of one embodiment of the present invention and a schematic diagram illustrating the correlation between energy levels of a light-emitting layer. [Figure 7] 1 is a schematic cross-sectional view of a light-emitting element according to one embodiment of the present invention. [Figure 8] 1 is a schematic cross-sectional view of a light-emitting element according to one embodiment of the present invention. [Figure 9] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a light-emitting element of one embodiment of the present invention. [Figure 10] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a light-emitting element of one embodiment of the present invention. [Figure 11] 1A and 1B are a top view and a cross-sectional schematic diagram illustrating a display device of one embodiment of the present invention. [Figure 12] 1A and 1B are schematic cross-sectional views illustrating a display device according to one embodiment of the present invention. [Figure 13] 1A and 1B are schematic cross-sectional views illustrating a display device according to one embodiment of the present invention. [Figure 14] 1A and 1B are schematic cross-sectional views illustrating a display device according to one embodiment of the present invention. [Figure 15] 1A and 1B are schematic cross-sectional views illustrating a display device according to one embodiment of the present invention. [Figure 16] 1A and 1B are schematic cross-sectional views illustrating a display device according to one embodiment of the present invention. [Figure 17] 1A and 1B are schematic cross-sectional views illustrating a display device according to one embodiment of the present invention. [Figure 18] 1A and 1B are schematic cross-sectional views illustrating a display device according to one embodiment of the present invention. [Figure 19] 1A and 1B are schematic cross-sectional views illustrating a display device according to one embodiment of the present invention. [Figure 20] 1A and 1B are a block diagram and a circuit diagram illustrating a display device of one embodiment of the present invention. [Figure 21] FIG. 1 is a circuit diagram illustrating a pixel circuit of a display device according to one embodiment of the present invention. [Figure 22] FIG. 1 is a circuit diagram illustrating a pixel circuit of a display device according to one embodiment of the present invention. [Figure 23] FIG. 1 is a perspective view illustrating an example of a touch panel of one embodiment of the present invention. [Figure 24] 1 is a cross-sectional view illustrating an example of a display device and a touch sensor according to one embodiment of the present invention. [Diagram 25] FIG. 1 is a cross-sectional view illustrating an example of a touch panel of one embodiment of the present invention. [Figure 26] 1A and 1B are a block diagram and a timing chart of a touch sensor according to one embodiment of the present invention. [Figure 27] FIG. 1 is a circuit diagram of a touch sensor according to one embodiment of the present invention. [Figure 28] FIG. 1 is a perspective view illustrating a display module of one embodiment of the present invention. [Figure 29] 1A to 1C illustrate electronic devices of one embodiment of the present invention. [Diagram 30] 1A to 1C illustrate electronic devices of one embodiment of the present invention. [Diagram 31] 1A to 1C illustrate electronic devices of one embodiment of the present invention. [Diagram 32] FIG. 1 is a perspective view illustrating a display device according to one embodiment of the present invention. [Diagram 33] 1A and 1B are a perspective view and a cross-sectional view illustrating a light-emitting device of one embodiment of the present invention. [Diagram 34] FIG. 1 is a cross-sectional view illustrating a light-emitting device according to one embodiment of the present invention. [Diagram 35] 1A to 1C illustrate a lighting device and an electronic device according to one embodiment of the present invention. [Diagram 36] 1A to 1C are diagrams illustrating a lighting device according to one embodiment of the present invention. [Figure 37] 1 is a schematic cross-sectional view illustrating a light-emitting element according to an embodiment. [Figure 38] FIG. 13 is a graph showing current efficiency vs. luminance characteristics of a light-emitting element in the embodiment. [Figure 39] FIG. 13 is a graph showing luminance-voltage characteristics of a light-emitting element in the example. [Diagram 40] FIG. 13 is a graph showing external quantum efficiency vs. luminance characteristics of a light-emitting element according to an embodiment. [Diagram 41] FIG. 13 is a graph showing power efficiency vs. luminance characteristics of a light-emitting element in the embodiment. [Diagram 42] FIG. 2 is a graph showing electroluminescence spectra of light-emitting elements according to an embodiment of the present invention. [Diagram 43] FIG. 2 is a diagram illustrating an emission spectrum of a host material according to an example. [Diagram 44] FIG. 4 is a diagram illustrating transient fluorescence characteristics of a host material in the example. [Diagram 45] 4A to 4C are diagrams illustrating absorption spectra and emission spectra of guest materials in the examples. [Figure 46] FIG. 13 is a graph showing current efficiency vs. luminance characteristics of a light-emitting element in the embodiment. [Figure 47] FIG. 13 is a graph showing luminance-voltage characteristics of a light-emitting element in the example. [Figure 48] FIG. 13 is a graph showing external quantum efficiency vs. luminance characteristics of a light-emitting element according to an embodiment. [Figure 49] FIG. 13 is a graph showing power efficiency vs. luminance characteristics of a light-emitting element in the embodiment. [Figure 50] FIG. 2 is a graph showing electroluminescence spectra of light-emitting elements according to an embodiment of the present invention. [Figure 51] FIG. 13 is a graph showing current efficiency vs. luminance characteristics of a light-emitting element in the embodiment. [Figure 52]FIG. 13 is a graph showing luminance-voltage characteristics of a light-emitting element in the example. [Figure 53] FIG. 13 is a graph showing external quantum efficiency vs. luminance characteristics of a light-emitting element according to an embodiment. [Figure 54] FIG. 13 is a graph showing power efficiency vs. luminance characteristics of a light-emitting element in the embodiment. [Figure 55] FIG. 2 is a graph showing electroluminescence spectra of light-emitting elements according to an embodiment of the present invention. [Figure 56] 4A to 4C are diagrams illustrating absorption spectra and emission spectra of guest materials in the examples. [Figure 57] FIG. 13 is a graph showing current efficiency vs. luminance characteristics of a light-emitting element in the embodiment. [Figure 58] FIG. 13 is a graph showing luminance-voltage characteristics of a light-emitting element in the example. [Figure 59] FIG. 13 is a graph showing external quantum efficiency vs. luminance characteristics of a light-emitting element according to an embodiment. [Figure 60] FIG. 13 is a graph showing power efficiency vs. luminance characteristics of a light-emitting element in the embodiment. [Figure 61] FIG. 2 is a graph showing electroluminescence spectra of light-emitting elements according to an embodiment of the present invention. [Figure 62] FIG. 2 is a diagram illustrating an emission spectrum of a host material according to an example. [Figure 63] FIG. 4 is a diagram illustrating transient fluorescence characteristics of a host material in the example. [Figure 64] FIG. 13 is a graph showing current efficiency vs. luminance characteristics of a light-emitting element in the embodiment. [Figure 65] FIG. 13 is a graph showing luminance-voltage characteristics of a light-emitting element in the example. [Figure 66] FIG. 13 is a graph showing external quantum efficiency vs. luminance characteristics of a light-emitting element according to an embodiment. [Figure 67] FIG. 13 is a graph showing power efficiency vs. luminance characteristics of a light-emitting element in the embodiment. [Figure 68] FIG. 2 is a graph showing electroluminescence spectra of light-emitting elements according to an embodiment of the present invention. [Figure 69] FIG. 13 is a graph showing current efficiency vs. luminance characteristics of a light-emitting element in the embodiment. [Figure 70]FIG. 13 is a graph showing luminance-voltage characteristics of a light-emitting element in the example. [Figure 71] FIG. 13 is a graph showing external quantum efficiency vs. luminance characteristics of a light-emitting element according to an embodiment. [Figure 72] FIG. 13 is a graph showing power efficiency vs. luminance characteristics of a light-emitting element in the embodiment. [Figure 73] FIG. 2 is a graph showing electroluminescence spectra of light-emitting elements according to an embodiment of the present invention. [Figure 74] FIG. 2 is a diagram illustrating an emission spectrum of a host material according to an example. [Figure 75] 4A to 4C are diagrams illustrating absorption spectra and emission spectra of guest materials in the examples. [Figure 76] FIG. 13 is a graph showing current efficiency vs. luminance characteristics of a light-emitting element in the embodiment. [Figure 77] FIG. 13 is a graph showing luminance-voltage characteristics of a light-emitting element in the example. [Figure 78] FIG. 13 is a graph showing external quantum efficiency vs. luminance characteristics of a light-emitting element according to an embodiment. [Figure 79] FIG. 13 is a graph showing power efficiency vs. luminance characteristics of a light-emitting element in the embodiment. [Figure 80] FIG. 2 is a graph showing electroluminescence spectra of light-emitting elements according to an embodiment of the present invention. [Figure 81] FIG. 2 is a diagram illustrating an emission spectrum of a host material according to an example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, the embodiment 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 are not limited to those described above 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 of the present disclosure are not to be construed as being limited to the content.

[0027] In addition, the position, size, range, etc. of each component shown in the drawings are not necessarily shown in order to facilitate understanding. The actual position, size, range, etc. may not be shown. The present invention is not necessarily limited to the position, size, range, etc. disclosed in the drawings, etc.

[0028] In addition, in this specification, ordinal numbers such as 1st, 2nd, etc. are used for convenience. In some cases, the order of steps or layers may not be indicated. For example, "first" may be replaced with "second" or " " can be appropriately replaced with "the third" etc. The ordinal numbers used to identify an aspect of the present invention may not match those used in the present invention. be.

[0029] In addition, in this specification and the like, when explaining the configuration of the invention using drawings, The reference numerals may be commonly used among different drawings.

[0030] 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:

[0031] In this specification and the like, the singlet excited state (S * ) is a single charge 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 T1 level is a triplet The lowest excited energy level of the triplet excited state. In this specification and the like, the term "singlet excited state" and "singlet excited energy" are used interchangeably. Even when written as the energy level, it refers to the lowest singlet excited state and the S1 level. In some cases, the triplet excited state and triplet excited energy level are also used. may represent the lowest triplet excited state and the T1 level.

[0032] In the present specification and the like, a fluorescent material refers to a material that, when relaxed 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 a triplet excited 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 that can convert triplet excitation energy into visible light.

[0033] In addition, the phosphorescence emission energy or triplet excitation energy is the shortest wavelength side of phosphorescence emission. It can be derived from the wavelength of the emission peak (including the shoulder) or the onset. The phosphorescence is observed by time-resolved photoluminescence in a low-temperature (e.g., 10 K) environment. The emission energy of thermally activated delayed fluorescence is , the shortest wavelength emission peak (including shoulder) or rising edge of thermally activated delayed fluorescence can be derived from the wavelength of

[0034] In this specification and the like, room temperature refers to any temperature between 0°C and 40°C.

[0035] In this specification, the blue wavelength region refers to wavelengths of 400 nm or more and less than 500 nm. blue emission has at least one emission spectrum peak in that region. The green wavelength region is the wavelength region between 500 nm and 580 nm. Green emission is emission having at least one emission spectrum peak in this region. The red wavelength region is the wavelength region between 580 nm and 680 nm. The emission is an emission having at least one emission spectrum peak in said region.

[0036] (Embodiment 1) In this embodiment, a light-emitting element of one embodiment of the present invention will be described below with reference to FIGS. Reveal.

[0037] <Configuration example 1 of light-emitting element> First, the structure of a light-emitting element of one embodiment of the present invention will be described with reference to FIGS. This is explained below.

[0038] FIG. 1A is a schematic cross-sectional view of a light-emitting element 150 of one embodiment of the present invention.

[0039] The light emitting element 150 has a pair of electrodes (electrode 101 and electrode 102). The EL layer 100 includes at least a light-emitting layer 130. .

[0040] The EL layer 100 shown in FIG. 1A includes a hole injection layer 111, a hole injection layer 112, a light emitting layer 130, and a cathode. It has functional layers such as a hole transport layer 112 , an electron transport layer 118 , and an electron injection layer 119 .

[0041] In this embodiment, of the pair of electrodes, electrode 101 is an anode, and electrode 1 Although the description will be given assuming that 02 is a cathode, the configuration of the light-emitting element 150 is not limited to this. The electrode 101 is a cathode, the electrode 102 is an anode, and the layers between the electrodes are stacked in the reverse order. That is, from the anode side, the hole injection layer 111, the hole transport layer 112, and the light emitting layer 113 may be arranged in that order. The light-emitting layer 130, the electron transport layer 118, and the electron injection layer 119 may be laminated in this order. .

[0042] The configuration of the EL layer 100 is not limited to the configuration shown in FIG. 1(A). At least one selected from the group consisting of a hole transport layer 112, an electron transport layer 118, and an electron injection layer 119. Alternatively, the EL layer 100 may be a hole or electron injector. Reducing the barrier, improving the transportability of holes or electrons, reducing the transportability of holes or electrons or suppressing the quenching phenomenon caused by the electrode. Each functional layer may be a single layer or a laminate of multiple layers. It may be composed of

[0043] FIG. 1(B) is a schematic cross-sectional view showing an example of the light-emitting layer 130 shown in FIG. The light-emitting layer 130 shown in FIG.

[0044] 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 a host material 132 .

[0045] In addition, a light-emitting organic material may be used as the guest material 131. The material is preferably one that has a function of converting triplet excitation energy into light emission. It is particularly preferable that the material be a material capable of emitting phosphorescence (hereinafter also referred to as phosphorescent material). In the following description, a configuration in which a phosphorescent material is used as the guest material 131 will be described. Therefore, the guest material 131 may be interpreted as a phosphorescent material.

[0046] <Light Emitting Mechanism of Light Emitting Device 1> Next, the light emitting mechanism of the light emitting layer 130 will be described below.

[0047] In the light-emitting element 150 according to one embodiment of the present invention, a pair of electrodes (electrode 101 and electrode 102) By applying a voltage between the cathode and the anode, electrons flow from the cathode and holes flow from the anode. The electrons and holes are then injected into the EL layer 100, causing a current to flow. As a result, the guest material 131 in the light-emitting layer 130 of the EL layer 100 is excited. Thus, light can be emitted from the excited guest material 131.

[0048] Light emission from the guest material 131 is obtained through the following two processes. ·(α) Direct recombination process (β) Energy transfer process

[0049] ≪(α) Direct recombination process≫ First, the direct recombination process in the guest material 131 will be described. holes) recombine in the guest material 131, forming an excited state of the guest material 131. In this case, the required excitation energy for the direct carrier recombination process in the guest material131 is The energy of the lowest unoccupied orbital of the guest material 131 is Molecular Orbital (LUMO) levels and the Highest Occupied Molecular Orbital (Hi ghest occupied molecular orbital, also known as HOMO c) The energy difference depends on the energy difference between the singlet excited state and the On the other hand, since the guest material 131 is a phosphorescent material, the energy of the triplet excited state corresponds to Therefore, the guest material 131 forms a singlet excited state and a triplet excited state. When the energy difference between the excited state and the singlet excited state is large, the energy required to excite the guest material 131 is The energy is higher than the light emission energy by the amount corresponding to the energy difference. It becomes.

[0050] The energy required to excite the guest material 131 and the energy of emission are The difference in power consumption affects the characteristics of the light-emitting device as a difference in the driving voltage. α) In the direct recombination process, the emission start voltage of the light-emitting element is It becomes larger than the voltage equivalent to the energy of light emission.

[0051] In addition, when the guest material 131 has high emission energy, the LU of the guest material 131 Because the MO level is high, it becomes difficult for the electrons (carriers) to be injected into the guest material 131. , direct recombination of carriers (electrons and holes) in the guest material 131 becomes difficult. Therefore, it is difficult to obtain high luminous efficiency in the light-emitting element.

[0052] <(β) Energy transfer process> Next, in order to explain the energy transfer process between the host material 132 and the guest material 131, FIG. 2(A) shows a schematic diagram for explaining the correlation of the energy levels. The notations and symbols used are as follows: Guest(131): Guest material 131 (phosphorescent material) ·Host(132): Host material 132 ·S G : S1 level of guest material 131 (phosphorescent material) T G :T1 level of guest material 131 (phosphorescent material) ·S H: S1 level of the host material 132 T H : T1 level of the host material 132

[0053] The carriers recombine in the host material 132, and the host material 132 enters a singlet excited state. When the triplet excited state is formed, the route E in Figure 2(A) 1 and Route E 2 Shown in Thus, both the singlet excitation energy and the triplet excitation energy of the host material 132 are , the singlet excited energy level of the host material 132 (S H ) and triplet excited energy levels (T H ) to the triplet excited energy level (T G ) and move to guest material The guest material 131 enters a triplet excited state. Light emission is obtained.

[0054] The singlet excitation energy level (S H ) 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 is calculated from 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 be efficiently transferred to

[0055] In other words, in the light-emitting layer 130, excitation energy from the host material 132 to the guest material 131 is Energy is being provided.

[0056] 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 support material 131.

[0057] In addition, the singlet excitation energy of the host material 132 is smaller than the triplet excitation energy of the guest material 131. Energy level (T G ) to reduce the energy loss in the transfer to 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.

[0058] FIG. 2B shows an energy band diagram of the guest material 131 and the host material 132. In FIG. 2(B), Guest(131) represents the guest material 131, and Hos t(132) represents the host material 132, and ΔE G is the LUMO level of the guest material 131 and H It represents the energy difference with the OMO level, ΔE H is the LUMO level of the host material 132 and the HOM represents the energy difference with the O level, ΔE B is the LUMO level of the host material 132 and the guest material This is the notation and symbol that represents the energy difference from the HOMO level of 131.

[0059] The guest material 131 emits light with a short wavelength and large emission energy. In order to achieve this, the energy difference between the LUMO level and the HOMO level of the guest material 131 (ΔE G On the other hand, in order to reduce the driving voltage of the light emitting device 150, It is preferable that the host is excited with as small an excitation energy as possible. It is preferable that the excitation energy of the excited state formed by the material 132 is small. The energy difference between the LUMO level and the HOMO level of the host material 132 (ΔE H ) is small is preferred.

[0060] Since the guest material 131 is a phosphorescent light-emitting material, it emits triplet excitation energy. The triplet excited state is also a much more energetic state than the singlet excited state. Therefore, the guest material 131 has a stable LUMO level and a stable HOMO level. The energy difference (ΔE G ) can emit light with lower energy than The energy difference between the LUMO level and the HOMO level of this guest material 131 (ΔE G ) but The energy difference between the LUMO and HOMO levels of the 132 material (ΔE H ) larger than Even in this case, the emission energy (abbreviation: ΔE Em ) or suck The transition energy calculated from the absorption edge in the absorption spectrum (abbreviation: ΔE abs ) is Δ E H If the excitation current is equal to or smaller than the excitation current of the host material 132, the gate This allows the transfer of excitation energy to the guest material 131, resulting in light emission from the guest material 131. The present inventors have found that it is possible to obtain a ΔE G However, the guest material The luminescence energy of 131 (ΔE Em ) or from the absorption edge in the absorption spectrum The calculated transition energy (ΔE abs ), the guest material 131 is directly charged. To excite the electrons, ΔE G Since a large amount of electrical energy equivalent to However, in one embodiment of the present invention, the driving voltage of ΔE H (ΔE G Less than The host material 132 is electrically excited by electrical energy corresponding to The excited state of the guest material 131 is generated by the electron transfer, which allows for low driving voltage and high efficiency. Therefore, light emission from the guest material 131 can be obtained at a high efficiency. The optical element has a light emission start voltage (luminance of 1cd / m 2 The guest material exhibits a voltage that is larger than the The energy of the emitted light (ΔE Em ) can be made smaller than the voltage equivalent to , ΔE G The emission energy (ΔE Em ) or absorption spectrum The transition energy (ΔE abs ) is much larger than In this case (for example, when the guest material is a blue light-emitting material), one embodiment of the present invention is particularly beneficial. The light emission energy (ΔE Em ) is the emission peak at the shortest wavelength side of the emission spectrum. It can be derived from the wavelength of the peak (including the maximum or shoulder) or the rise do.

[0061] In addition, when the guest material 131 has a heavy metal, spin-orbit interaction (electron spin angle The interaction between the orbital momentum and the orbital angular momentum promotes intersystem crossing between the singlet and triplet states. Since the guest material 131 is driven by the singlet ground state and the triplet excited state, In other words, the singlet ground state and triplet excited state of the guest material 131 may be allowed. The efficiency of emission and the probability of absorption associated with the transition between the two states can be increased. The guest material 131 preferably has a metal element with a large spin-orbit coupling, and in particular, Metal group elements (ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium ( It is preferable that the metal oxide has a metal oxide layer containing 1,000 mol / L of iridium (Ir), or platinum (Pt), among which 1,000 mol / L is preferably iridium (Ir), or platinum (Pt). The inclusion of rhodium enhances the absorption of the direct transition between the singlet ground state and the triplet excited state. This is preferable since it can increase the yield rate.

[0062] Note that the guest material 131 emits light having high emission energy (short wavelength). For this purpose, it is preferable that the lowest triplet excited energy level of the guest material 131 is high. For this purpose, the ligands that coordinate to the heavy metal atoms of the guest material 131 must also have at least three It is preferable that the first excitation energy level is high, the electron-accepting property is low, and the LUMO level is high. is preferred.

[0063] The guest material with the above structure is a molecule with a high HOMO level that easily accepts holes. When the guest material 131 has a molecular structure that easily accepts holes, The HOMO level of the material 131 may be higher than the HOMO level of the host material 132. Furthermore, ΔE G is ΔE H If the LUMO level of the guest material 131 is larger than that of the host The LUMO level of the guest material 131 is higher than that of the guest material 132. The energy difference between the LUMO level of the guest material 131 and the LUMO level of the host material 132 is The energy difference between the O level and the HOMO level of the host material 132 becomes larger.

[0064] Here, the HOMO level of the guest material 131 is higher than the HOMO level of the host material 132. When the LUMO level of the guest material 131 is higher than the LUMO level of the host material 132, Carriers (holes and electrons) injected from a pair of electrodes (electrodes 101 and 102) ), the holes injected from the anode are injected into the guest material 131 in the light-emitting layer 130. Therefore, electrons injected from the cathode are easily injected into the host material 132. Therefore, the guest material 131 and the host material 132 may form an exciplex. In particular, the energy between the LUMO level of the host material 132 and the HOMO level of the guest material 131 is -Difference (ΔE B ) is the light emission energy (ΔE Em ) As the temperature increases, the generation of an exciplex formed between the guest material 131 and the host material 132 increases. In this case, the guest material 131 alone is unlikely to generate an excited state, so The light emitting efficiency of the light emitting element is reduced.

[0065] The above reaction can be represented by the following general formula (G11) or (G12).

[0066] H - +G + → (H G) * (G11) H+G * → (H G) * (G12)

[0067] In the general formula (G11), the host material 132 accepts electrons (H -), Guest Material 131 accepts a hole (G + ) to form an exciplex of the host material 132 and the guest material 131. ((H·G) * In addition, general formula (G12) is a reaction that produces Stock material 131(G * ) interacts with the ground state host material 132 (H) The host material 132 and the guest material 131 are exciplexes (H G) * ) The host material 132 and the guest material 131 form an exciplex ((H G) * ) is formed By this, the excited state of the guest material 131 alone (G * ) becomes difficult to generate.

[0068] The exciplex formed by the host material 132 and the guest material 131 is an exciplex formed by the L The energy difference between the UMO level and the HOMO level of the guest material 131 (ΔE B ) roughly equivalent to However, the LUM of the host material 132 The energy difference between the O level and the HOMO level of the guest material 131 (ΔE B ) is the guest material The luminescence energy of 131 (ΔE Em ) or the absorption edge in the absorption spectrum? The transition energy (ΔE abs ) or more, the host material 132 and the guest The reaction of forming an exciplex with the guest material 131 can be suppressed, and the guest material 131 can be efficiently The present inventors have found that it is possible to obtain light emission with high efficiency. abs but ΔE B Since the guest material 131 is smaller, it is easier for the guest material 131 to receive excitation energy, and the host material Rather than forming an exciplex between 132 and the guest material 131, the guest material 131 has an excitation energy of 132. The excited state that receives energy is lower and more stable.

[0069] As described above, the energy between the LUMO level and the HOMO level of the guest material 131 is -Difference (ΔE G ) is the energy difference between the LUMO level and the HOMO level of the host material 132 ( ΔE H ) even if the absorption edge in the absorption spectrum of the guest material 131 is larger than The transition energy (ΔE abs ) is ΔE H If it is equal to or smaller than The excitation energy is efficiently transferred from the excited host material 132 to the guest material 131. As a result, one of the features of one embodiment of the present invention is that a light-emitting element that operates at a low voltage and has high efficiency can be obtained. At this time, ΔE G >ΔE H ≧ΔE abs (ΔE G is ΔE H Larger, ΔE H teeth ΔE abs Therefore, the LUMO level and HOM level of the guest material 131 are The energy difference between the O level (ΔE G ) in the absorption spectrum of the guest material 131 The transition energy (ΔE abs ) is larger than the me of one embodiment of the present invention. More specifically, the LUMO and HOMO levels of the guest material 131 are preferably The energy difference between the G ) is the absorption edge in the absorption spectrum of the guest material 131. The transition energy (ΔE abs ) is preferably 0.3 eV or more larger, and 0 It is more preferable that the emission energy of the guest material 131 is larger than 0.4 eV. (ΔE Em ) is ΔE abs The LU of the guest material 131 is equal to or smaller than that of the The energy difference between the MO level and the HOMO level (ΔE G ) is the luminescence of guest material 131. Energy (ΔE Em ) is preferably 0.3 eV or more larger, and more preferably 0.4 eV or more larger. It is more preferable.

[0070] Furthermore, the HOMO level of the guest material 131 is higher than the HOMO level of the host material 132. As mentioned above, when B ≧ΔE abs (ΔE B is ΔE abs or more), or ΔE B ≧ΔE Em (ΔE B is ΔE Em Therefore, ΔE G >ΔE H >ΔE B ≧ΔE abs (ΔE G is ΔE H Larger, ΔE H is ΔE B Larger, ΔE B is ΔE abs or more), or ΔE G >ΔE H >ΔE B ≧ΔE Em (ΔE G is ΔE H twist Large, ΔE H is ΔE B Larger, ΔE B is ΔE Em These are preferably This condition is also an important discovery in one embodiment of the present invention.

[0071] In addition, the energy difference between the LUMO level and the HOMO level of the host material 132 (ΔE H )teeth , the singlet excited energy level of the host material 132 (S H ) is equal to or slightly larger than the The singlet excited energy level (S H ) is the triplet excited energy level (T H ) is larger than the triplet excited energy level (T H ) is a guest The triplet excited energy level (T G ) is greater than ΔE G >ΔE H ≧S H >T H ≧T G (ΔE G is ΔE H Larger, ΔE H is S H That's it. S H is T H Bigger, T H is T G In addition, in the absorption spectrum of the guest material 131, The absorption at the absorption edge in the ZnSe band is the absorption at the singlet ground state and the triplet excited state of the guest material 131. When the absorption is related to the transition, ΔT G is ΔE abs The energy is equal to or slightly smaller than that. Therefore, ΔE G is ΔE abs In order for the ΔE G and ΔE abs From the energy difference with H and T H It is preferable that the energy difference between Specifically, H and T H The energy difference between the eV or less, and more preferably, greater than 0 eV and less than or equal to 0.1 eV.

[0072] The energy difference between the singlet and triplet excited energy levels is small, A suitable material for the fluorescent material 132 is a thermally activated delayed fluorescent material. vated delayed fluorescence (TADF) materials. Thermally activated delayed fluorescent materials have an energy level between singlet and triplet excitation levels. The energy difference is small, and triplet excitation energy is converted to singlet excitation energy by reverse intersystem crossing. Note that the host material 132 according to one embodiment of the present invention has a function of being able to be converted into It is not necessarily T H From S H The efficiency of reverse intersystem crossing to S is not required to be high. H Light emission from Since the molecular yield does not need to be high, a wide range of materials can be selected.

[0073] In addition, the energy difference between the singlet excited energy level and the triplet excited energy level is reduced. In order to reduce the amount of the hole transport, the host material 132 should have a structure having a hole transporting function (hole transporting property). and a skeleton having a function of transporting electrons (electron transport property). In this case, the excited state of the host material 132 is such that the HOMO molecular orbital is attached to the skeleton having hole transport properties. Since the electron-transporting skeleton has a LUMO molecular orbital, the HOMO molecular orbital The overlap between the molecular orbital of the donor and the LUMO is extremely small. -Acceptor type excited states are more easily formed, and the singlet and triplet excited energy levels In the host material 132, the energy difference between the excitation energy level and the Singlet excited energy level (S H) and triplet excited energy level (T H ) is favorable. The value is generally greater than 0 eV and equal to or less than 0.2 eV.

[0074] In addition, the molecular orbital represents the spatial distribution of electrons in a molecule and can represent the probability of finding an electron. Molecular orbitals allow us to determine in detail the electronic configuration of a molecule (the spatial distribution and energy of electrons). It is possible to describe it in detail.

[0075] In addition, when the host material 132 has a skeleton with strong donor properties, the The holes are easily injected into the host material 132 and transported. When the host material has a skeleton with a strong acceptor property, the electrons injected into the light-emitting layer 130 are In this way, the excited state is easily injected into the host material 132 and transported. This is preferred because it is easier to form.

[0076] In addition, the emission wavelength of the guest material 131 becomes shorter, and the emission energy (ΔE Em ) is large The larger the energy difference between the LUMO and HOMO levels of the guest material 131 (ΔE G ) becomes large, and accordingly, large energy is required to directly electrically excite the guest material. However, in one embodiment of the present invention, the adsorption of the guest material 131 is The transition energy (ΔE abs ) is ΔE H and If it is equal to or smaller, ΔE G ΔE is smaller than H With just that much energy Since the photoresist material 131 can be excited, the power consumption of the light-emitting element can be reduced. Therefore, the transition calculated from the absorption edge in the absorption spectrum of the guest material 131 is Energy (ΔE abs ) and the energy difference between the LUMO and HOMO levels of the guest material 131. Energy difference (ΔE G ) and the larger the energy difference between them (i.e., blue light is emitted more easily). In the case of a guest material exhibiting the above-mentioned light-emitting property, the effect of the light-emitting mechanism of one embodiment of the present invention becomes remarkable.

[0077] However, the transition energy calculated from the absorption edge in the absorption spectrum of the guest material 131 is Gee(ΔE abs ) becomes smaller, the light emission energy (ΔE Em ) becomes smaller, so it is difficult to obtain light with high energy, such as blue light. It becomes difficult to do so. In other words, ΔE abs and ΔE G If the difference between Therefore, it becomes difficult to obtain light emission having high energy such as blue light emission.

[0078] From these results, the energy difference between the LUMO level and the HOMO level of the guest material 131 is (ΔE G ) is the transition energy calculated from the absorption edge in the absorption spectrum of the guest material 131. Energy (ΔE abs ) and it is preferable that the value is in the range of 0.3 eV to 0.8 eV. It is more preferable that the value is in the range of 0.4 eV to 0.8 eV. It is more preferable that the energy of the emission from the guest material 131 is large in the range of 0.1 eV or less. Energy (ΔE Em ) is ΔE abs Since it is equal to or smaller than the guest material 13 The energy difference between the LUMO level and the HOMO level of 1 (ΔE G ) is presented by guest material 131 The energy of the emitted light (ΔE Em ) is larger in the range of 0.3 eV to 0.8 eV It is preferable that the value is in the range of 0.4 eV to 0.8 eV, and more preferable that the value is larger than 0.5 eV. It is more preferable that the value is in the range of 0.8 eV or more and 0.8 eV or less.

[0079] In addition, the HOMO level of the guest material 131 is higher than the HOMO level of the host material 132. Therefore, the guest material 131 functions as a hole trap in the light-emitting layer 130 . When the guest material 131 functions as a hole trap, it facilitates the carrier balance in the light-emitting layer. This is preferable because it is possible to easily control the temperature and the lifetime can be extended. If the HOMO level of the material 131 is too high, the above-mentioned ΔE B becomes smaller. Therefore, the energy difference between the HOMO level of the guest material 131 and the HOMO level of the host material 132 is The energy difference is preferably 0.05 eV or more and 0.4 eV or less. The energy difference between the MO level and the LUMO level of the host material 132 is preferably 0.05 eV or more, more preferably 0.1 eV or more, and even more preferably 0.2 eV or more. This makes it easier for electron carriers to be injected into the host material 132. This is preferable.

[0080] In addition, the energy difference between the LUMO level and the HOMO level of the host material 132 (ΔE H )teeth , the energy difference between the LUMO level and the HOMO level of the guest material 131 (ΔE G ) less than Therefore, the carriers (holes and electrons) injected into the light-emitting layer 130 recombine to form excitation currents. As for the excited state, the excited state formed by the host material 132 is energetically stable. Therefore, the excited state generated by the direct recombination of carriers in the light-emitting layer 130 Most of the electrons will exist as excited states formed by the host material 132. In accordance with the configuration of one embodiment of the present invention, the excitation energy from the host material 132 to the guest material 131 is By facilitating the transfer of energy, the driving voltage of the light-emitting element can be reduced, and the light-emitting element can be The light efficiency can be increased.

[0081] In addition, based on the relationship between the LUMO level and the HOMO level described above, the oxidation potential of the guest material 131 is The oxidation potential is preferably lower than the oxidation potential of the host material 132. The potential can be measured by cyclic voltammetry (CV) method. .

[0082] 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 obtained efficiently.

[0083] <Energy transfer mechanism> Next, the control of the energy transfer process between the host material 132 and the guest material 131 molecules The mechanism of energy transfer between molecules is the Förster mechanism (bipolar Two mechanisms have been proposed: the electron-dipole interaction mechanism and the Dexter mechanism (electron exchange interaction). It is being done.

[0084] <Förster mechanism> In the Förster mechanism, the energy transfer does not require direct contact between the molecules, but occurs via the host Energy transfer occurs through the resonance phenomenon of dipole vibration between the material 132 and the guest material 131. The host material 132 transfers energy to the guest material 131 due to the resonance phenomenon of the dipole vibration. The excited host material 132 goes to the ground state, and the guest material 13 1 becomes excited. Note that the rate constant of the Förster mechanism is k h*→g is shown in formula (1). .

[0085]

number

[0086] In formula (1), ν represents the frequency, and f' h (ν) is the standard value of the host material 132 The emission spectrum (fluorescence spectrum when discussing energy transfer from a singlet excited state) is calculated. spectrum when discussing energy transfer from triplet excited states), ε g (ν) represents the molar extinction coefficient of the guest material 131, N represents Avogadro's number, and n represents the refractive index of the medium, and R represents the intermolecular distance between the host material 132 and the guest material 131. where τ is the measured lifetime of the excited state (fluorescence lifetime or phosphorescence lifetime) and c is the speed of light. , φ is the emission quantum yield (or the fluorescence quantum yield when considering energy transfer from a singlet excited state) When discussing energy transfer from a triplet excited state, it is the phosphorescence quantum yield, and when discussing energy transfer from a triplet excited state, it is the phosphorescence quantum yield, and K 2 teeth , a coefficient (between 0 and 131) that represents the orientation of the transition dipole moment of the host material 132 and the guest material 131 In the case of random orientation, K 2 =2 / 3.

[0087] <Dexter System> In the Dexter mechanism, the host material 132 and the guest material 131 are bonded together with orbital overlap. The electrons of the host material 132 in the excited state approach the effective distance from the guest material 13 in the ground state. Energy transfer occurs through the exchange of electrons with 1. The rate constant for the Dexter mechanism is k h*→g is shown in formula (2).

[0088]

number

[0089] In formula (2), h is the Planck constant, and K is a constant with the dimension of energy. where ν is the frequency and f' is the h (ν) is the normalized emission spectrum of the host material 132. Spectra (fluorescence spectrum when discussing energy transfer from singlet excited states, triplet When discussing energy transfer from an excited state, it represents the phosphorescence spectrum, and ε' g (ν) is , represents the normalized absorption spectrum of the guest material 131, L represents the effective molecular radius, R represents the intermolecular distance between the host material 132 and the guest material 131 .

[0090] Here, the energy transfer efficiency φ from the host material 132 to the guest material 131 ET is a number It is expressed by equation (3). r The emission process of the host material 132 (energy from the singlet excited state) When discussing energy transfer, we use the term fluorescence. When discussing energy transfer from triplet excited states, we use the term phosphorescence. light), and k n is the non-radiative process (thermal deactivation or intersystem crossing) of the host material 132. represents the rate constant, and τ represents the measured lifetime of the excited state of the host material 132.

[0091]

number

[0092] From equation (3), the energy transfer efficiency φET To increase the rate of energy transfer, Degree constant k h*→g By increasing the other competing rate constants k r +k n (=1 / τ) is relatively It turns out that the smaller it is, the better.

[0093] <Concept for improving energy transfer> In the case of energy transfer via the Förster mechanism, the energy transfer efficiency φ ET Is Light quantum yield φ (fluorescence quantum yield when considering energy transfer from a singlet excited state, When discussing energy transfer from triplet excited states, it is better to have a higher phosphorescence quantum yield. In addition, the emission spectrum of the host material 132 (energy transfer from the singlet excited state is discussed) In the case of the fluorescence spectrum) and the absorption spectrum (from the singlet ground state to the triplet ground state) of the guest material 131 It is preferable that the overlap with the absorption corresponding to the transition to the first excited state is large. It is also preferable that the molar extinction coefficient of the host material 131 is high. This means that the spectrum overlaps with the absorption band appearing on the longest wavelength side of the guest material 131. do.

[0094] In addition, in the energy transfer by the Dexter mechanism, the rate constant k h*→g Make it bigger In this study, the emission spectrum of the host material 132 (energy transfer from the singlet excited state) was discussed. If the energy transfer from the triplet excited state is discussed, the fluorescence spectrum is used. Absorption spectrum of the 131 guest material (from the singlet ground state to the triplet excited state) The greater the overlap with the absorption corresponding to the transition, the better. Therefore, the efficiency of energy transfer is The optimization is performed on the emission spectrum of the host material 132 and the longest wavelength side of the guest material 131. This is achieved by the overlap of the absorption bands of the

[0095] <Light-emitting element configuration example 2> Next, a light-emitting element having a different structure from that shown in FIG. 1(A)(B) will be described with reference to FIG. ) (B) will be used to explain the following.

[0096] FIG. 3A is a schematic cross-sectional view of a light-emitting element 152 according to one embodiment of the present invention. In FIG. 1(A), the same hatch pattern is used for the parts having the same functions as those shown in FIG. In addition, parts having similar functions are given similar reference symbols. In some cases, detailed description thereof will be omitted.

[0097] The light emitting element 152 has a pair of electrodes (electrode 101 and electrode 102). The EL layer 100 includes at least a light-emitting layer 135. .

[0098] FIG. 3(B) is a schematic cross-sectional view showing an example of the light-emitting layer 135 shown in FIG. The light-emitting layer 135 shown in FIG. 1B is made of at least a guest material 131, a host material 132, and a host and a ferroelectric material 133.

[0099] In the light-emitting layer 135, the host material 132 or the host material 133 is the most The guest material 131 is dispersed in the host material 132 and the host material 133. can be.

[0100] <Light Emitting Mechanism of Light Emitting Device 2> Next, the light emitting mechanism of the light emitting layer 135 will be described below.

[0101] The light-emitting element 152 according to one embodiment of the present invention also has a pair of electrodes (electrode 101 and electrode 102). The holes and electrons injected from the EL layer 100 are recombined to form a light-emitting layer. The guest material 131 in the semiconductor substrate 135 is excited, and the excited guest material 131 emits light. can be obtained.

[0102] Light emission from the guest material 131 is obtained through the following two processes. ·(α) Direct recombination process (β) Energy transfer process

[0103] The (α) direct recombination process is the same as that described in the light emission mechanism of the light emitting layer 130. Since this is similar to the recombination process, a description thereof will be omitted here.

[0104] <(β) Energy transfer process> The energy transfer process between the host material 132, the host material 133, and the guest material 131 is shown in FIG. For the purpose of explanation, a schematic diagram for explaining the correlation of energy levels is shown in FIG. The notations and symbols in 4(A) are as follows. For other notations and symbols, see FIG. Same as 2(A). ·Host(133): Host material 133 ·S A : S1 level of the host material 133 T A : T1 level of the host material 133

[0105] The carriers recombine in the host material 132, and the host material 132 enters a singlet excited state. When the triplet excited state is formed, route E in Figure 4(A) 1 and Route E 2 Shown in Thus, both the singlet excitation energy and the triplet excitation energy of the host material 132 are The singlet excited energy level (S H ) and triplet excited energy level ( T H ) to the triplet excited energy level (T G ) and move onto the guest material The guest material 131 in the triplet excited state emits phosphorescence. Light emission is obtained.

[0106] In addition, the excitation energy is efficiently transferred from the host material 132 to the guest material 131. In order to achieve this, the triplet excited energy level (T A ) is the host material 132 The triplet excited energy level (T H ) is preferably higher than that of the host material. The triplet excitation energy of the guest material 132 is less likely to be quenched, and the guest material 13 is efficiently Energy transfer occurs to 1.

[0107] In addition, as shown in the energy band diagram in Figure 4(B), the HOMO level of the guest material 131 When the HOMO level of the host material 132 is higher than the HOMO level of the host material 132, the light-emitting mechanism 1 of the light-emitting device is as described above. As mentioned above, the energy difference between the LUMO and HOMO levels of the guest material 131 (ΔE G ) is the energy difference (ΔE H ) greater than It is preferable to have a larger ΔE H is the LUMO level of the host material 132 and the LUMO level of the guest material 131. Energy difference with the HOMO level (ΔE B ) is preferable.

[0108] In addition, the LUMO level of the host material 133 is higher than the LUMO level of the host material 132. and the HOMO level of the host material 133 is lower than the HOMO 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 host material 132 and the HOMO level of the guest material 131. Energy difference (ΔE B ) larger than the host material 133 and the host material 13 A reaction of forming an exciplex with 2, and a reaction of forming an exciplex with the host material 133 and the guest material 131. In FIG. 4(B), the reaction of forming the host (13 3) represents a host material 133, and other notations and symbols are the same as those in FIG. 2(B).

[0109] In addition, the difference between the LUMO level of the host material 133 and the LUMO level of the host material 132, The difference between the HOMO level of the host material 133 and the HOMO 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 electron injected from a pair of electrodes (electrodes 101 and 102) Electron and hole carriers are transported through the host material 132 and the guest material 131, respectively. This is preferable because it can be easily injected into the

[0110] The LUMO level of the host material 133 is higher than the LUMO level of the guest material 131. The HOMO level of the host material 133 may be higher or lower than the HOMO level of the host material 132. It can be higher or lower than the level.

[0111] The energy difference between the LUMO level and the HOMO level of the host material 133 is The energy difference between the LUMO and HOMO levels of the material 132 (ΔE H ) is preferable. At this time, the energy difference (ΔE H ) is the energy difference (ΔE G )Yo Since the carriers (holes and electrons) injected into the light-emitting layer 135 are smaller than the The excited state of the host material 133 and the guest material 131 is that they are excited singly. It is more energetically stable for the host material 132 to form an excited state than for the host material 132 to form an excited state. Therefore, the excitation current generated by the direct recombination of carriers in the light-emitting layer 135 is Most of the states will exist as excited states formed by the host material 132. Therefore, in the light-emitting layer 135, similarly to the configuration of the light-emitting layer 130 described above, the host material 1 By facilitating the transfer of excitation energy from the excited state of 32 to the guest material 131, Therefore, the driving voltage of the light emitting element 152 can be reduced, and the light emitting efficiency can be improved.

[0112] In addition, holes and electrons recombine in the host material 133 to excite the host material 133. Even when an excited state is formed, the LUMO level and the HOMO level of the host material 133 are not aligned. The energy difference is smaller than the energy difference between the LUMO level and the HOMO level of the host material 132. When the excitation energy of the host material 133 is large, the excitation energy of the host material 132 is rapidly transferred to the host material 132. The excitation energy can then be transferred to the light-emitting mechanism of the light-emitting layer 130 described above. Through a similar process, energy is transferred to the guest material 131, and the guest material 131 It is to be noted that holes and electrons are also regenerated in the host material 133. Considering that the host material 133 can be bonded to the singlet excited state, similarly to the host material 132, It is preferable that the material has a small energy difference between the energy level and the triplet excited energy level. In particular, it is preferable that the material be a thermally activated delayed fluorescent material.

[0113] In order to obtain efficient emission from the guest material 131, the singlet excited electrons of the host material 133 must be Energy level (S A ) is the singlet excited energy level (S H ) That's all The triplet excited energy level (T A ) is the third of the host material 132 Singlet excited energy level (T H ) or more is preferable.

[0114] In addition, from the relationship between the LUMO level and the HOMO level described above, the reduction potential of the host material 133 The reduction potential of the host material 132 is lower than the oxidation potential of the host material 133. It is preferable that the oxidation potential of the resist material 131 be higher than that of the resist material 131 .

[0115] In addition, the combination of the host material 132 and the host material 133 has a function of transporting holes. When a material having a function of transporting electrons is combined with a material having a function of transporting electrons, the mixing ratio Therefore, it is possible to easily control the carrier balance. The ratio of the material having the function of transporting electrons to the material having the function of transporting electrons is 1:9 to 9:1 (weight ratio). In addition, by having this configuration, the carrier balance can be easily controlled. This makes it possible to easily control the carrier recombination region.

[0116] By configuring the light-emitting layer 135 as described above, light emission from the guest material 131 of the light-emitting layer 135 can be obtained efficiently.

[0117] <Material> Next, components of a light-emitting element according to one embodiment of the present invention will be described in detail below.

[0118] <Light-emitting layer> In the light-emitting layer 130 and the light-emitting layer 135, the host material 132 contains at least one guest material 132. The guest material 131 (phosphorescent material) is present in a larger amount by weight than the host material 132. It is distributed.

[0119] <Host Material 132> The energy difference between the S1 level and the T1 level of the host material 132 is preferably small. Specifically, it is greater than 0 eV and less than or equal to 0.2 eV.

[0120] The host material 132 has a skeleton having a hole transporting property and a skeleton having an electron transporting property. Alternatively, the host material 132 may preferably have a π-electron rich heteroaromatic skeleton or It is preferable that the compound has an aromatic amine skeleton and a π-electron deficient heteroaromatic ring skeleton. This makes it easier to form donor-acceptor excited states within the molecule. The electron transporting property is set so that both donor and acceptor properties are strong in the molecule of the electron transporting material 132. It is preferable that the skeleton having the hole transporting property and the skeleton having the hole transporting property are directly bonded to each other. Alternatively, a π-electron rich heteroaromatic ring skeleton or aromatic amine skeleton and a π-electron deficient hetero It is preferable that the aromatic ring structure has a structure in which the aromatic ring structure is directly bonded to the aromatic ring structure. By strengthening both the terpene and the terpene, the molecular orbitals in the HOMO of the host material 132 are distributed. The overlap between the region and the region in which the molecular orbitals in the LUMO are distributed can be reduced, The energies of the singlet and triplet excited energy levels of the host material 132 In addition, the triplet excitation energy level of the host material 132 can be reduced. This makes it possible to maintain the position at a high energy level.

[0121] Materials with a small energy difference between the singlet and triplet excited energy levels Examples of the thermally activated delayed fluorescent material include a triplet Since the difference between the excited energy level and the singlet excited energy level is small, reverse intersystem crossing occurs. This material has the function of converting energy from a triplet excited state to a singlet excited state. Therefore, the triplet excited state can be upconverted to the singlet excited state by a small amount of thermal energy. It is possible to undergo reverse intersystem crossing and efficiently emit light (fluorescence) from the singlet excited state. In addition, the condition for efficiently obtaining thermally activated delayed fluorescence is that the triplet excitation energy The energy difference between the singlet excited energy level and the singlet excited energy level is preferably greater than 0 eV. It is preferably 0.2 eV or less, and more preferably more than 0 eV and 0.1 eV or less. can be.

[0122] When the thermally activated delayed fluorescent material is composed of one kind of material, for example, the following material is used: It is possible.

[0123] First, fullerene and its derivatives, acridine derivatives such as proflavine, and eosin are listed. In addition, magnesium (Mg), zinc (Zn), cadmium (Cd), tin (S n), platinum (Pt), indium (In), or palladium (Pd) Examples of the metal-containing porphyrin include protoporphyrin. Fluorine-tin fluoride complex (SnF 2 (Proto IX)), mesoporphyrin-fluoride Tin complex (SnF 2 (Meso IX)), hematoporphyrin-tin fluoride complex (Sn F 2 (Hemato IX), coproporphyrin tetramethyl ester-tin fluoride Complex (SnF 2 (Copro III-4Me)), Octaethylporphyrin-fluoride Tin complex (SnF 2 (OEP)), etioporphyrin-tin fluoride complex (SnF 2 (E tio I), octaethylporphyrin-platinum chloride complex (PtCl 2 OEP) etc. Can be obtained.

[0124] [ka]

[0125] In addition, as a thermally activated delayed fluorescent material composed of one kind of material, π-electron-rich heteroaromatic Heterocyclic compounds having an aromatic ring and a π-electron deficient heteroaromatic ring can also be used. 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 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 PPZ-3TPT, 3-(9,9-dimethyl- 9H-Acridine-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. Since the heterocyclic compound has a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring, Among them, a skeleton having a π-electron-deficient heteroaromatic ring is preferable because it has high transport properties and hole transport properties. Among them, diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton) and triazine skeleton The azine skeleton is preferred because it is stable and reliable. Among the skeletons that can be used, the acridine skeleton, the phenoxazine skeleton, the phenothiazine skeleton, and the furan skeleton are Since the thiophene skeleton and pyrrole skeleton are stable and reliable, It is preferable that the furan skeleton has at least one of the following structure: The thiophene skeleton is preferably a dibenzothiophene skeleton. The skeleton includes an indole skeleton, a carbazole skeleton, and a 9-phenyl-3,3'-biphenyl skeleton. In addition, a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring are particularly preferable. The substance in which the heteroaromatic ring is directly bonded to the π-electron-rich heteroaromatic ring exhibits the donor property of the π-electron-deficient heteroaromatic ring. The acceptor properties of both the heteroaromatic rings are strong, and the levels of the singlet excited state and the triplet excited state are high. In addition, the π-electron-deficient heteroaromatic ring is preferably a silyl group. An aromatic ring having an electron withdrawing group such as an ano group attached thereto may also be used.

[0126] [ka]

[0127] In addition, examples of the skeleton having a π-electron-deficient heteroaromatic ring include condensed heteroaromatic rings having a diazine skeleton. The ring skeleton is preferred because it is more stable and has good reliability, and among them, the benzofuropyrimidine skeleton and The benzothienopyrimidine skeleton is particularly preferred because of its high acceptor property. An example of the pyrimidine skeleton is the benzofuro[3,2-d]pyrimidine skeleton. In addition, the benzothienopyrimidine skeleton is, for example, benzothieno[3,2-d] A pyrimidine skeleton is exemplified.

[0128] As a skeleton having a π-electron-rich heteroaromatic ring, a bicarbazole skeleton is The bicarbazole skeleton is preferably one of the following: A bicarbazole skeleton in which two carbazolyl groups are bonded to each other at any one of positions 1 to 4. The bicarbazole skeleton is particularly preferred because of its high donor property. ,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. .

[0129] From the viewpoint of widening the band gap and increasing the triplet excitation energy, The 9-position of one of the carbazolyl groups in the bicarbazole skeleton is directly connected to a benzofuropyrimidinyl group. Compounds bonded to a pyrimidine skeleton or a benzothienopyrimidine skeleton are preferred. A carbazole skeleton and a benzofuropyrimidine skeleton or a benzothienopyrimidine skeleton. When directly bonded, it becomes a compound with a relatively low molecular weight, which is suitable for vacuum deposition (relatively low temperature). Generally, the lower the molecular weight, the lower the heat resistance after film formation. Although the activity is often low, benzofuropyrimidine skeleton, benzothienopyrimidine skeleton, Since the bicarbazole skeleton is a rigid skeleton, compounds having this skeleton have a relatively high molecular weight. It is possible to have sufficient heat resistance even if the temperature is relatively low. This is preferred because it results in a larger gap and a higher excitation energy level.

[0130] In addition, the bicarbazole skeleton and the benzofuropyrimidine skeleton or the benzothienopyrimidine skeleton are and the alkylene skeleton is bonded via an arylene group, and the number of carbon atoms of the arylene group is is 6 to 25, preferably 6 to 13, the band gap and triplet Not only can the excitation energy of the cyclopentadiene be kept high, but the molecular weight of the compound is relatively low. This results in a structure that is suitable for vacuum deposition (vacuum deposition can be performed at a relatively low temperature).

[0131] In addition, the bicarbazole skeleton is linked to benzofuro[3,2 -d]pyrimidine backbone or benzothieno[3,2-d]pyrimidine backbone. More preferably, the benzofuro[3,2-d]pyrimidine skeleton or the benzothieno[3,2- d] By bonding to the 4-position of the pyrimidine skeleton, the compound has excellent carrier transport properties. Therefore, a light-emitting element using the compound can be driven at a low voltage. do.

[0132] Compound Example 1 A compound suitable for the light-emitting element of one embodiment of the present invention described above is represented by the following general formula (G0): It is a compound that can be

[0133] [ka]

[0134] In the above general formula (G0), A represents a substituted or unsubstituted benzofuropyrimidine skeleton. or benzothienopyrimidine skeleton. When the zothienopyrimidine skeleton has a substituent, the substituent may be a C1-C6 an alkyl group, a cycloalkyl group having 3 to 7 carbon atoms, or a substituted or unsubstituted alkyl group having 6 carbon atoms; Aryl groups having 1 to 13 carbon atoms can also be selected as substituents. Specific examples of the group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, Examples of the alkyl group include 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 cyclobutene group, and a cyclobutene group. Examples of the alkyl group include cyclohexyl, cyclopentyl, and cyclohexyl. The aryl group having 6 to 13 carbon atoms includes a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, and the like. Specific examples include aryl groups.

[0135] Also, R 1 ~R 15 each independently represents a hydrogen atom or a substituted or unsubstituted group having 1 to 10 carbon atoms; a substituted or unsubstituted alkyl group having 3 to 7 carbon atoms, or a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms; or an unsubstituted aryl group having 6 to 13 carbon atoms. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, Examples of the alkyl group include 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, 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, and a fluoro group. Specific examples include the alkyl group and the cycloalkyl 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. Cycloalkyl groups having up to 7 carbon atoms or aryl groups having 6 to 13 carbon atoms are also selected as substituents. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, Propyl, isopropyl, butyl, isobutyl, tert-butyl, n-hexyl Examples of the cycloalkyl group having 3 to 7 carbon atoms include 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.

[0136] Also, Ar 1 represents an arylene group having 6 to 25 carbon atoms or a single bond, The aryl group may have substituents, and the substituents may be bonded to each other to form a ring. An example of such a compound is a fluorenyl group having a phenyl group as a substituent at the 9-position carbon. The two phenyl groups are bonded 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, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, Examples of the alkyl group include aryl groups having 3 or more carbon atoms, tert-butyl groups, and n-hexyl groups. Specific examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclobutyl group, and a cyclopropyl group. Also, examples of the alkyl group having 6 to 13 carbon atoms include a cyclopentyl group and a cyclohexyl group. The aryl group includes a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, etc. can be cited as an example.

[0137] In the compound represented by the general formula (G0), the benzofuropyrimidine skeleton is The benzothienopyrimidine skeleton is preferably a thifluoro[3,2-d]pyrimidine skeleton. The skeleton is preferably a benzothieno[3,2-d]pyrimidine skeleton.

[0138] In the compound represented by the general formula (G0), At the 9-position of the zolyl group, either directly or via an arylene group, benzofuro[3,2-d] The pyrimidine skeleton or benzothieno[3,2-d]pyrimidine skeleton is bonded to the 4-position of the structure. Compounds with this structure have both strong donor and acceptor properties and have a wide band gap. Therefore, it can be suitably used for light emitting elements that emit high energy light, such as blue light. This is a particularly preferred embodiment of the compound. The compound is represented by the following general formula (G1).

[0139] [ka]

[0140] In the above general formula (G1), Q represents oxygen or sulfur.

[0141] Also, R 1 ~R 20 each independently represents a hydrogen atom or a substituted or unsubstituted group having 1 to 10 carbon atoms; a substituted or unsubstituted alkyl group having 3 to 7 carbon atoms, or a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms; or an unsubstituted aryl group having 6 to 13 carbon atoms. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, Examples of the alkyl group include 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, 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, and a fluoro group. Specific examples include the alkyl group and the cycloalkyl 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. Cycloalkyl groups having up to 7 carbon atoms or aryl groups having 6 to 13 carbon atoms are also selected as substituents. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, Propyl, isopropyl, butyl, isobutyl, tert-butyl, n-hexyl Examples of the cycloalkyl group having 3 to 7 carbon atoms include 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.

[0142] Also, Ar 1 represents an arylene group having 6 to 25 carbon atoms or a single bond, The aryl group may have substituents, and the substituents may be bonded to each other to form a ring. An example of such a compound is a fluorenyl group having a phenyl group as a substituent at the 9-position carbon. The two phenyl groups are bonded 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, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, Examples of the alkyl group include aryl groups having 3 or more carbon atoms, tert-butyl groups, and n-hexyl groups. Specific examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclobutyl group, and a cyclopropyl group. Also, examples of the alkyl group having 6 to 13 carbon atoms include a cyclopentyl group and a cyclohexyl group. The aryl group includes a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, etc. can be cited as an example.

[0143] In the compound represented by the general formula (G1), the bicarbazole skeleton is 3,3'- A bi-9H-carbazole skeleton, 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 having a structure bonded to the 4-position of the hexagonal or benzothieno[3,2-d]pyrimidine skeleton Since the material has excellent carrier transport properties, light-emitting elements using this material can be driven at low voltages. This is a preferred configuration. The compound is a compound represented by the following general formula (G2).

[0144] [ka]

[0145] In the above general formula (G2), Q represents oxygen or sulfur.

[0146] Also, R 1 ~R 20 each independently represents a hydrogen atom or a substituted or unsubstituted group having 1 to 10 carbon atoms; a substituted or unsubstituted alkyl group having 3 to 7 carbon atoms, or a substituted or unsubstituted cycloalkyl group having 3 to 7 carbon atoms; or an unsubstituted aryl group having 6 to 13 carbon atoms. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, Examples of the alkyl group include 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, 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, and a fluoro group. Specific examples include the alkyl group and the cycloalkyl 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. Cycloalkyl groups having up to 7 carbon atoms or aryl groups having 6 to 13 carbon atoms are also selected as substituents. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, Propyl, isopropyl, butyl, isobutyl, tert-butyl, n-hexyl Examples of the cycloalkyl group having 3 to 7 carbon atoms include 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.

[0147] Also, Ar 1 represents an arylene group having 6 to 25 carbon atoms or a single bond, The aryl group may have substituents, and the substituents may be bonded to each other to form a ring. An example of such a compound is a fluorenyl group having a phenyl group as a substituent at the 9-position carbon. The two phenyl groups are bonded together to form a spirofluorene skeleton. Examples of the arylene group having 6 to 13 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, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, Examples of the alkyl group include aryl groups having 3 or more carbon atoms, tert-butyl groups, and n-hexyl groups. Specific examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclobutyl group, and a cyclopropyl group. Also, examples of the alkyl group having 6 to 13 carbon atoms include a cyclopentyl group and a cyclohexyl group. The aryl group includes a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, etc. can be cited as an example.

[0148] In the compound represented by the general formula (G1) or (G2), and a benzofuropyrimidine skeleton or a benzothienopyrimidine skeleton are directly bonded to each other. In the case of the compound, the band gap is improved and it is possible to synthesize the compound with high purity. In addition, since the compound has excellent carrier transport properties, the use of the compound is The light-emitting element can be driven at a low voltage.

[0149] In addition, in the above general formula (G1) or (G2), R 1 ~R 14 , and R 16 ~ R 20 However, if all the hydrogen is used, it is advantageous in terms of ease of synthesis and the cost of the raw materials. In particular, since the compound has a relatively low molecular weight, it has a structure suitable for vacuum deposition, which is particularly preferable. The compound is represented by the following general formula (G3) or (G4).

[0150] [ka]

[0151] In the above general formula (G3), Q represents oxygen or sulfur.

[0152] Also, R 15 is hydrogen, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, or unsubstituted cycloalkyl groups having 3 to 7 carbon atoms, or substituted or unsubstituted cycloalkyl groups having 6 to 7 carbon atoms. The alkyl group having 1 to 6 carbon atoms is specifically any one of the aryl groups having 1 to 6 carbon atoms. is a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and te Examples of the alkyl group include butyl groups and n-hexyl groups. Specific examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, and a cyclopentyl group. Examples of the aryl group include aryl groups having 6 to 13 carbon atoms. Specific examples of the aryl group include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. In addition, the above-mentioned alkyl groups, cycloalkyl groups, and aryl groups can be mentioned. The alkyl 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, Alternatively, an aryl group having 6 to 13 carbon atoms can be selected as a substituent. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and an isopropyl group. Examples of the butyl group, isobutyl group, tert-butyl group, and n-hexyl group are mentioned. Specific examples of the cycloalkyl group having 3 to 7 carbon atoms include cyclopropyl. Examples of the aryl 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, and a biphenyl group. , fluorenyl group, etc. can be mentioned as specific examples.

[0153] Also, Ar 1 represents an arylene group having 6 to 25 carbon atoms or a single bond, The aryl group may have substituents, and the substituents may be bonded to each other to form a ring. An example of such a compound is a fluorenyl group having a phenyl group as a substituent at the 9-position carbon. The two phenyl groups are bonded 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, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, Examples of the alkyl group include aryl groups having 3 or more carbon atoms, tert-butyl groups, and n-hexyl groups. Specific examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclobutyl group, and a cyclopropyl group. Also, examples of the alkyl group having 6 to 13 carbon atoms include a cyclopentyl group and a cyclohexyl group. The aryl group includes a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, etc. can be cited as an example.

[0154] [ka]

[0155] In the above general formula (G4), Q represents oxygen or sulfur.

[0156] Also, R 15 is hydrogen, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, or unsubstituted cycloalkyl groups having 3 to 7 carbon atoms, or substituted or unsubstituted cycloalkyl groups having 6 to 7 carbon atoms. The alkyl group having 1 to 6 carbon atoms is specifically any one of the aryl groups having 1 to 6 carbon atoms. is a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and te Examples of the alkyl group include butyl groups and n-hexyl groups. Specific examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, and a cyclopentyl group. Examples of the aryl group include aryl groups having 6 to 13 carbon atoms. Specific examples of the aryl group include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. In addition, the above-mentioned alkyl groups, cycloalkyl groups, and aryl groups can be mentioned. The alkyl 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, Alternatively, an aryl group having 6 to 13 carbon atoms can be selected as a substituent. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and an isopropyl group. Examples of the butyl group, isobutyl group, tert-butyl group, and n-hexyl group are mentioned. Specific examples of the cycloalkyl group having 3 to 7 carbon atoms include cyclopropyl. Examples of the aryl 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, and a biphenyl group. , fluorenyl group, etc. can be mentioned as specific examples.

[0157] Also, Ar 1 represents an arylene group having 6 to 25 carbon atoms or a single bond, The aryl group may have substituents, and the substituents may be bonded to each other to form a ring. An example of such a compound is a fluorenyl group having a phenyl group as a substituent at the 9-position carbon. The two phenyl groups are bonded 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, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, Examples of the alkyl group include aryl groups having 3 or more carbon atoms, tert-butyl groups, and n-hexyl groups. Specific examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclobutyl group, and a cyclopropyl group. Also, examples of the alkyl group having 6 to 13 carbon atoms include a cyclopentyl group and a cyclohexyl group. The aryl group includes a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, etc. can be cited as an example.

[0158] In the general formula (G0), the benzofuropyrimidine skeleton or benzothiamine skeleton represented by A is Examples of the enopyrimidine skeleton include those represented by the following structural formulas (Ht-1) to (Ht-24). The structures that can be used for A are as follows: Not limited to.

[0159] [ka]

[0160] [ka]

[0161] In the above structural formulas (Ht-1) to (Ht-24), R 16 ~R 20 are respectively Independently, hydrogen, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted a cycloalkyl group having 3 to 7 carbon atoms, or a substituted or unsubstituted cycloalkyl 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, tert-butyl group Examples of the cycloalkyl group having 3 to 7 carbon atoms include an n-hexyl group and an n-hexyl group. Specific examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, Examples of the aryl group having 6 to 13 carbon atoms include cyclohexyl and the like. Specific examples of the aryl group include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. In addition, the above-mentioned alkyl, cycloalkyl, and aryl groups can be substituted. The substituents may be bonded to each other to form a ring. Examples of the alkyl group include an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, and a carbon Aryl groups having 6 to 13 carbon atoms can also be selected as substituents. Specific examples of alkyl groups include methyl, ethyl, propyl, isopropyl, and butyl. Examples of the alkyl group include 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 cycloalkyl group, and a cycloalkyl group. butyl group, cyclopentyl group, cyclohexyl group, etc. The aryl group having 6 to 13 carbon atoms includes a phenyl group, a naphthyl group, a biphenyl group, a fluorene group, and the like. A specific example is a cycloalkyl group.

[0162] In addition, in the general formulae (G0) and (G1), it can be used as a bicarbazole skeleton. Examples of structures that can be obtained include structures represented by the following structural formulas (Cz-1) to (Cz-9). The following structure can be used as the bicarbazole skeleton: Not limited to these.

[0163] [ka]

[0164] [ka]

[0165] In the above structural formulas (Cz-1) to (Cz-9), R 1 ~R 15 are independent of each other hydrogen, a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted carbon atom, a cycloalkyl group having 3 to 7 prime 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, Ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl and n-hexyl groups. Cycloalkyl groups having 3 to 7 carbon atoms are also examples. Specific examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cycloalkyl group. Examples of the aryl group having 6 to 13 carbon atoms include: Specific examples include phenyl, naphthyl, biphenyl, and fluorenyl groups. Furthermore, the above-mentioned alkyl group, cycloalkyl group, and aryl group can have a substituent. The substituents may be bonded to each other to form a ring. is an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, or a cycloalkyl group having 6 carbon atoms. Aryl groups having 1 to 13 carbon atoms can also be selected as substituents. Specific examples of the group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, Examples of the alkyl group include 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, and a cyclopropyl group. Examples of the aryl group include cyclopentyl group, cyclohexyl group, and the like. The aryl group of 13 to 15 includes a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, Specific examples include the following:

[0166] In addition, in the above general formulae (G0) to (G4), Ar 1 The arylene group represented by the formula: For example, groups represented by the following structural formulas (Ar-1) to (Ar-27) can be used. In addition, Ar 1 The groups that can be used as are not limited to these, and may have a substituent. That's fine.

[0167] [ka]

[0168] [ka]

[0169] In addition, R in the above general formulas (G1) and (G2) 1 ~R 20 R in general formula (G0) 1 ~ R 15 R in general formula (G3) and (G4) 15 an alkyl group represented by the formula: The group or aryl group is, for example, a group represented by the following structural formulas (R-1) to (R-29). In addition, the alkyl group, the cycloalkyl group, or the aryl group may be The groups that can be used are not limited to these, and may have a substituent.

[0170] [ka]

[0171] <Specific examples of compounds> Specific structures of the compounds represented by the above general formulae (G0) to (G4) include the following: Compounds represented by the structural formulas (100) to (147) are also included. The compounds represented by (0) to (G4) are not limited to the following examples.

[0172] [ka]

[0173] [ka]

[0174] [ka]

[0175] [ka]

[0176] [ka]

[0177] [ka]

[0178] [ka]

[0179] [ka]

[0180] Compound Example 2 The host material 132 has a singlet excitation energy level and a triplet excitation energy level. The energy difference between the two is small, and the efficiency of reverse intersystem crossing is not necessarily high. It is not necessary for the yield to be high, and it is not necessary for the compound to have a function of exhibiting thermally activated delayed fluorescence. The host material 132 is a compound having a structure having a π-electron-rich heteroaromatic ring or an aromatic amine structure. At least one of the two and the skeleton having a π-electron deficient heteroaromatic ring is an m-phenylene group or It is preferable that the bond is formed via a structure having at least one o-phenylene group. Alternatively, it is preferable that the bond is via a biphenyldiyl group. via an arylene group having at least one -phenylene group or o-phenylene group It is preferable that the arylene group has a structure in which the aryl group is bonded to the aryl group, and the arylene group is preferably a biphenyldiyl group. This is more preferable because the T1 level of the host material 132 can be increased. In this case, the skeleton having a π-electron deficient heteroaromatic ring is a diazine skeleton (π at least one of a pyridine skeleton, a pyrazine skeleton, a pyridazine skeleton, and a triazine skeleton The skeleton having a π-electron-rich heteroaromatic ring is preferably an acridine. skeleton, phenoxazine skeleton, phenothiazine skeleton, furan skeleton, thiophene skeleton, and It is preferable that the olefin skeleton is at least one of a dibenzofuran skeleton and a furan skeleton. As the thiophene skeleton, a dibenzothiophene skeleton is preferable. The pyrrole skeleton includes an indole skeleton, a carbazole skeleton, and a 9-phenyl In addition, an aromatic amine skeleton and As the amine, a so-called tertiary amine having no NH bond is preferred, and in particular a triarylamine. The aryl group of the triarylamine skeleton is preferably A substituted or unsubstituted aryl group having 6 to 13 carbon atoms is preferable, and a phenyl group, a naphthyl group, Examples thereof include a fluorenyl group.

[0181] Examples of the above-mentioned aromatic amine skeleton and skeleton having a π-electron-rich heteroaromatic ring include the following: The skeletons are represented by the following general formulas (401) to (417). X in (416) represents an oxygen atom or a sulfur atom.

[0182] [ka]

[0183] An example of the skeleton having the π-electron-deficient heteroaromatic ring is a skeleton represented by the following general formula (20 The skeleton represented by (1) through (218).

[0184] [ka]

[0185] A skeleton with hole transport properties (specifically, a π-electron-rich heteroaromatic skeleton or an aromatic amine) At least one of the skeletons) and a skeleton having electron transport properties (specifically, a π-electron deficient heteroaromatic ring skeleton) has at least one m-phenylene group or o-phenylene group When the bond is formed via a biphenyldiyl group as a bonding group, has an arylene group having at least one m-phenylene group or o-phenylene group In the case where the bond is formed via a bonding group, examples of the bonding group include those represented by the following general formulas (301) to (302). The arylene group is represented by the following formula (315): , biphenyldiyl skeleton, naphthalenediyl skeleton, fluorenediyl skeleton, phenanthrenyl skeleton Examples include a benzoyl skeleton.

[0186] [ka]

[0187] The aromatic amine skeleton (specifically, triarylamine skeleton), π-electron-rich heterostructure Aromatic ring skeleton (specifically, acridine skeleton, phenoxazine skeleton, phenothiazine skeleton, A ring having at least one of a lanthanide skeleton, a thiophene skeleton, and a pyrrole skeleton, and a π-electron deficient A compound having a heteroaromatic ring structure (specifically, at least one of a diazine structure and a triazine structure) or the above general formulae (401) to (417), general formulae (201) to (2 18) and general formulae (301) to (315) may have a substituent. Examples of the group include an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, and A substituted or unsubstituted aryl group having 6 to 12 carbon atoms may also be used as a substituent. 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, tert-butyl group Examples of the cycloalkyl group include a cycloalkyl group having 3 to 6 carbon atoms, and a n-hexyl group. Specific examples of the alkyl group include a cyclopropyl group, a cyclobutyl group, and a cyclopentyl group. In addition, aryl groups having 6 to 12 carbon atoms, such as aryl groups and cyclohexyl groups, can be given. Specific examples of the alkyl group include a phenyl group, a naphthyl group, and a biphenyl group. The above-mentioned substituents may be bonded to each other to form a ring. For example, the 9-position carbon of the fluorene skeleton has two phenyl groups as substituents. In this case, the phenyl groups are bonded to each other to form a spirofluorene skeleton. In addition, the unsubstituted form is advantageous in terms of ease of synthesis and the cost of raw materials. do.

[0188] Also, Ar 2 represents an arylene group having 6 to 13 carbon atoms, and the arylene group is The substituents may be bonded to each other to form a ring. For example, the 9-position carbon of the fluorenyl group has two phenyl groups as substituents, When the phenyl groups are bonded to each other to form a spirofluorene skeleton, Examples of the arylene group having 6 to 13 carbon atoms include a phenylene group, a naphthyl group, and the like. Specific examples include a ethylene group, a biphenylene group, and a fluorenediyl group. In addition, when the arylene group has a substituent, the substituent may be a group having 1 to 2 carbon atoms. an alkyl group having 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or a cycloalkyl group having 6 to 6 carbon atoms; Aryl groups having 1 to 6 carbon atoms can also be selected as substituents. Specific examples of alkyl groups include methyl, ethyl, propyl, isopropyl, and butyl. Examples of the alkyl group include an isobutyl group, a tert-butyl group, and an n-hexyl group. Specific examples of the cycloalkyl group having 3 to 6 carbon atoms include a cyclopropyl group, Examples of the aryl group include a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a naphthyl group, and a biphenyl group. Specific examples include the following:

[0189] Also, Ar 2 The arylene group represented by the structural formula (Ar-1) to (Ar -18) can be used. 2 Can be used as The groups are not limited to these.

[0190] Also, R 21 and R 22 each independently represents hydrogen, alkyl having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or a substituted or unsubstituted alkyl group having 6 or more carbon atoms; An aryl group having 1 to 6 carbon atoms is an aryl group having 1 to 6 carbon atoms. Specifically, the alkyl group includes a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and an isopropyl group. Examples of the alkyl group having 3 carbon atoms include aryl, tert-butyl, and n-hexyl groups. Specific examples of the cycloalkyl group having 6 to 6 carbon atoms include a cyclopropyl group, a cyclobutyl group, and the like. Examples of the aryl group include cyclopentyl group, cyclohexyl group, and the like. Examples of the aryl group having 1 to 13 carbon atoms include a phenyl group, a naphthyl group, a biphenyl group, a fluoro group, and the like. Specific examples include the above-mentioned aryl group and phenyl group. The 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 6 carbon atoms, and An alkyl group or an aryl group having 6 to 12 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, and a propyl group. propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, n-hexyl group Examples of cycloalkyl groups having 3 to 6 carbon atoms include Specifically, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl Examples of the aryl group having 6 to 12 carbon atoms include fluoro groups. Specific examples include a phenyl group, a naphthyl group, and a biphenyl group.

[0191] Also, R 21 and R 22 The alkyl group or aryl group represented by the following structure is, for example, Groups represented by formulas (R-1) to (R-29) can be used. Alternatively, groups that can be used as the aryl group are not limited to these.

[0192] In addition, the general formulae (401) to (417), (201) to (218), and ( 301) to (315), and Ar 2 , R 21 and R 22 The substituents which may be carried by For example, an alkyl group or an aryl group represented by the above structural formulas (R-1) to (R-24) In addition, the alkyl group or the aryl group can be an alkyl group or an aryl group. The groups are not limited to these.

[0193] In addition, the emission peak of the host material 132 is triplet with that of the guest material 131 (phosphorescent material). Term MLCT (Metal to Ligand Charge Transfer) transition The host material 132 and It is preferable to select the guest material 131 (phosphorescent material) as the luminous efficiency. However, the thermal activation delay can be used instead of the phosphorescent material. When using fluorescent materials, the absorption band on the longest wavelength side is the singlet absorption band. preferable.

[0194] <Guest Material 131> The guest material 131 (phosphorescent material) is an iridium, rhodium, or platinum-based organic Metal complexes, particularly organic iridium complexes, such as iridium The ortho-metal complex is preferably a 4H-triazole. Ligand, 1H-triazole ligand, imidazole ligand, pyridine ligand, pyrimidine Ligands include pyrazine ligands, isoquinoline ligands, and the like. Examples include platinum complexes having porphyrin ligands.

[0195] In addition, the guest material 131 (phosphorescent material) is a material having a HOMO level lower than that of the host material 132. It has a high HOMO level and the energy of the LUMO level and the HOMO level of the host material 132 is close to each other. The host material 1 is arranged so as to have an energy difference between the LUMO level and the HOMO level higher than the It is preferable to select the guest material 131 (phosphorescent material) as the luminescent material. A light-emitting element that is highly efficient and can be driven at a low voltage can be provided.

[0196] Examples of substances having a green or yellow emission peak include tris(4-methyl-6 -phenylpyrimidinato)iridium(III) (abbreviation: Ir(mppm) 3 ), Tris (4-t-Butyl-6-phenylpyrimidinato)iridium(III) (abbreviation: Ir(t Buppm) 3 ), (acetylacetonato)bis(6-methyl-4-phenylpyrimidina G) Iridium (III) (abbreviation: Ir(mppm) 2 (acac)), (acetylacetone) Tritonato)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)), (Acetyl Ruacetonato)bis(4,6-diphenylpyrimidinato)iridium(III)(Abbreviation: Ir(dppm) 2 Organometallic iridium with a pyrimidine skeleton, such as (acac) Complexes and (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)i Ir(mppr-Me) 2 (acac)), (acetylacetone) 5-isopropyl-3-methyl-2-phenylpyrazinate) bis(5-isopropyl-3-methyl-2-phenylpyrazinate) iridium ( III) (Abbreviation: Ir(mppr-iPr) 2 (acac) Organometallic iridium complexes and tris(2-phenylpyridinato-N,C 2’ ) Iridi Ir(ppy) 3 ), Bis(2-phenylpyridinato-N,C 2 ’ ) Iridium(III) acetylacetonate (abbreviation: Ir(ppy) 2 (acac) ), bis(benzo[h]quinolinato)iridium(III) acetylacetonate (abbreviation :Ir(bzq) 2 (acac)), tris(benzo[h]quinolinato)iridium (I II) (Abbreviation: Ir(bzq) 3 ), tris(2-phenylquinolinato-N,C 2’ )stomach Ir(pq) 3 ), Bis(2-phenylquinolinato-N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: Ir(pq) 2 (acac) ), and bis(2,4-diphenyl -1,3-Oxazolato-N,C 2’ ) Iridium(III) acetylacetonate (abbreviation Name: Ir(dpo) 2 (acac)), bis{2-[4'-(perfluorophenyl) fluorine 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 (acac In addition to organometallic iridium complexes such as tris(acetylacetonato)(monophenanthate), Terbium(III) (abbreviation: Tb(acac) 3 Rare earth metals such as (Phen) Among the above, organometallic iridium complexes having a pyrimidine skeleton are The complex is particularly preferred because it has outstanding reliability and luminous efficiency.

[0197] Examples of substances having a yellow or red emission peak include 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(naphthalene-1-yl)pyrimidinyl] Nato](dipivaloylmethanato)iridium(III) (abbreviation: Ir(d1npm) 2 ( Organometallic iridium complexes with pyrimidine skeletons such as (acetylacetamide) Iridium(III) r(tppr) 2 (acac)), bis(2,3,5-triphenylpyrazinate)(dipyridine) Valoylmethanato)iridium(III) (abbreviation: Ir(tppr) 2 (dpm)), ( Acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]i Ir(Fdpq) 2 (acac)) Organometallic iridium complexes and 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 ( In addition to organometallic iridium complexes with pyridine skeletons such as acac), 2,3,7, 8,12,13,17,18-Octaethyl-21H,23H-porphyrin platinum(II) ) (abbreviation: PtOEP) and tris(1,3-diphenyl-1,3-propanediol). (Eu(DB))(monophenanthroline)europium(III) M) 3 (Phen)), tris[1-(2-thenoyl)-3,3,3-trifluoroacetate [Tonato](monophenanthroline)europium(III)(abbreviation: Eu(TTA) 3 ( Among the above, rare earth metal complexes such as pyrimidine skeletons are Organometallic iridium complexes having the above structure are particularly preferred because they are extremely reliable and have excellent luminous efficiency. In addition, organometallic iridium complexes with pyrazine skeletons can emit red light with good chromaticity. can be done.

[0198] Examples of substances having a blue or green emission peak include tris{2-[5-(2 -methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazo {3-yl-κN2]phenyl-κC}iridium(III) (abbreviation: Ir(mpp tz-dmp) 3 ), tris(5-methyl-3,4-diphenyl-4H-1,2,4-trimethyl Riazolato)iridium(III) (abbreviation: Ir(Mptz) 3 ), Tris[4-(3- Biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazolato]i Iridium(III) (abbreviation: Ir(iPrptz-3b) 3 ), Tris[3-(5-biphenyl (phenyl)-5-isopropyl-4-phenyl-4H-1,2,4-triazolato]irid Ir(III) (abbreviation: Ir(iPr5btz) 3 ), 4H-triazole skeleton such as and (OC-6-22)-tris{5-cyano-2-[ 4-(2,6-diisopropylphenyl)-5-(2-methylphenyl)-4H-1,2 ,4-Triazol-3-yl-κN 2 ]phenyl-κC}iridium(III) (abbreviation :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 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 ) with electron-withdrawing groups such as -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 rptz1-Me) 3 Organometallic iridium complexes with a 1H-triazole skeleton, such as body, 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 Iridium(III) (abbreviation: Ir(dmpimpt-Me) 3 ) such as imidazo Organometallic iridium complexes with a tetrafluoroethylene skeleton and bis[2-(4',6'-difluorophenyl) Nyl)pyridinato-N,C 2’ ]Iridium(III) tetrakis(1-pyrazolyl)boron FIr6, bis[2-(4',6'-difluorophenyl)pyridinate] -N,C 2’ ]Iridium(III) picolinate (abbreviation: FIrpic), bis{2- [3',5'-Bis(trifluoromethyl)phenyl]pyridinato-N,C 2’}Iridescent Ir(III) picolinate (abbreviation: Ir(CF 3 ppy) 2 (pic)), Bis[2- (4',6'-Difluorophenyl)pyridinato-N,C 2’ ]Iridium(III) A Phenyl groups with electron-withdrawing groups such as cetylacetonate (abbreviation: FIr(acac)) Organometallic iridium complexes having pyridine derivatives as ligands are also included. Nitrogen-containing structures such as 4H-triazole, 1H-triazole and imidazole skeletons Organometallic iridium complexes with five-membered heterocyclic rings have high triplet excitation energies. This is particularly preferable because it is excellent in reliability and luminous efficiency.

[0199] In addition, among the above-mentioned iridium complexes, the 4H-triazole skeleton and the 1H-triazole skeleton are Iridium with Nitrogen-Containing Five-Membered Heterocyclic Skeletons, Such as the Imidazole Skeleton In the case of iridium complexes and iridium complexes with pyridine skeletons, the ligands have low electron-accepting ability and the HOMO Since the level is likely to be high, this is suitable for one embodiment of the present invention.

[0200] In addition, among the organometallic iridium complexes having a nitrogen-containing five-membered heterocyclic skeleton, at least sialic acid is preferably used. Iridium complexes with substituents containing cyano groups are highly electron-withdrawing due to the strong electron-withdrawing properties of the cyano groups. Since the O level and the HOMO level are appropriately lowered, the compound is suitable for use in the light-emitting element of one embodiment of the present invention. In addition, the iridium complex has a high triplet excitation energy level. Therefore, by using the iridium complex in a light-emitting element, blue light with good luminous efficiency can be obtained. In addition, the iridium complex can be repeatedly oxidized and reduced, Since the iridium complex has good resistance to oxidation, it can be used in light-emitting devices to A light-emitting element with a long life can be manufactured.

[0201] From the viewpoint of stability and reliability of element characteristics, a cyano group is added to the nitrogen-containing five-membered heterocyclic skeleton. It is preferable that the iridium complex has a ligand having an aryl group containing the aryl group bonded thereto. The number of carbon atoms in the alkyl group is preferably 6 to 13. In this case, the iridium complex is Since vacuum deposition can be performed at a relatively low temperature, deterioration such as thermal decomposition during deposition is unlikely to occur.

[0202] In addition, a cyano group is bonded to a nitrogen atom of the nitrogen-containing five-membered heterocyclic skeleton via an arylene group. Iridium complexes with linked ligands can maintain a high triplet excited energy level. Therefore, it can be suitably used for light emitting elements that emit high energy light, such as blue light. In addition, compared to those without cyano groups, they emit blue light with high energy. Furthermore, the introduction of a cyano group at such a specific position results in a highly efficient light-emitting element. By doing so, it is possible to obtain a highly reliable light-emitting element that emits high-energy light such as blue light. In addition, between the nitrogen-containing five-membered heterocyclic skeleton and the cyano group, a phenanthroline bond is formed. Attachment via an arylene group, such as an aryl group, is preferred.

[0203] When the arylene group has 6 to 13 carbon atoms, the iridium complex is Since it is a compound with a comparatively low molecular weight, it is suitable for vacuum deposition (compounds that can be vacuum deposited at a relatively low temperature). In addition, generally, when the molecular weight is low, the heat resistance after film formation is poor. Since the iridium complex has multiple ligands, it has sufficient heat resistance even if the molecular weight of the ligands is low. This has the advantage of ensuring reliability.

[0204] That is, the iridium complex has the following advantages in addition to the ease of deposition and electrochemical stability described above: The triplet excitation energy level of the compound of the present invention is high. In a light-emitting element, the iridium complex is preferably used as a guest material in a light-emitting layer. Among these, it is particularly suitable for use as a guest material in a blue light-emitting device.

[0205] <Examples of iridium complexes> The above iridium complex is represented by the following general formula (G11).

[0206] [ka]

[0207] In the above general formula (G11), Ar 11 and Ar 12 Each independently has 6 carbon atoms. The aryl group having 6 to 13 carbon atoms is a substituted or unsubstituted aryl group having 6 to 13 carbon atoms. Specific examples of the aryl group include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. In the case where the aryl group has a substituent, the substituent may be an aryl group having 1 or more carbon atoms. an alkyl group having from 1 to 6 carbon atoms, a cycloalkyl group having from 3 to 6 carbon atoms, or a substituted group having from 6 to 13 carbon atoms; Alternatively, an unsubstituted aryl group can be selected as a substituent. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, Examples of the alkyl group include an isobutyl group, a tert-butyl group, and an n-hexyl group. Specific examples of the cycloalkyl group having 3 to 6 carbon atoms include a cyclopropyl group, 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, and a fluoro group. A specific example is an oleyl group.

[0208] Also, Q 1 and Q 2 each independently represents N or CR, R is hydrogen, an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, or a substituent having 6 to 13 carbon atoms; Q represents a substituted or unsubstituted aryl group. 1 and Q 2 At least one of the following is CR Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, and a propyl group. Phenyl, isopropyl, butyl, isobutyl, tert-butyl, n-hexyl Examples of the haloalkyl group having 1 to 6 carbon atoms include at least At least one hydrogen atom is converted by a group 17 element (fluorine, chlorine, bromine, iodine, astatine) Substituted alkyl groups include fluorinated alkyl groups, chlorinated alkyl groups, and brominated alkyl groups. Examples of the fluorinated alkyl group include methyl fluoride, methyl chloride, and fluorinated alkyl groups. Examples of halogen groups include ethyl groups and ethyl chloride groups. The type of each may be one or more. Specific examples of the group include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. Furthermore, the aryl group may have a substituent, and the above-mentioned substituent The groups may be bonded to each other to form a ring. The substituents include alkyl groups having 1 to 6 carbon atoms. A cycloalkyl group having 3 to 6 carbon atoms, or an aryl group having 6 to 13 carbon atoms may also be substituted. Specific examples of the alkyl group having 1 to 6 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl Examples of the aryl group include a cycloalkyl group having 3 to 6 carbon atoms, and a n-hexyl group. Specific examples of the alkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cycloalkyl group. Examples of the aryl group having 6 to 13 carbon atoms include cyclohexyl and the like. Specific examples of the aryl group include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. It is possible.

[0209] Also, Ar 11 and Ar 12 and an aryl group represented by R The other has a cyano group.

[0210] In addition, examples of iridium complexes that can be preferably used for the light-emitting element of one embodiment of the present invention include The iridium complex is preferably an orthometal complex. It is an iridium complex represented by the formula:

[0211] [ka]

[0212] In the above general formula (G12), Ar 11 is a substituted or unsubstituted aryl group having 6 to 13 carbon atoms. The aryl group having 6 to 13 carbon atoms includes a phenyl group, a naphthyl group, Specific examples of the aryl group include a biphenyl group and a fluorenyl group. When the group has a substituent, the substituent is an alkyl group having 1 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 the following: Methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert n-butyl group, n-hexyl group, etc. Specific examples of the alkyl group include a cyclopropyl group, a cyclobutyl group, and a cyclopentyl group. and cyclohexyl groups. In addition, aryl groups having 6 to 13 carbon atoms are also usable. Specific examples of the alkyl group include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. Some examples include:

[0213] Also, R 31 ~R 34 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, Cycloalkyl groups having 3 to 6 carbon atoms, substituted or unsubstituted aryl groups having 6 to 13 carbon atoms or a cyano group. Specific examples of the alkyl group having 1 to 6 carbon atoms include Methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert n-butyl group, n-hexyl group, etc. Specific examples of the alkyl group include a cyclopropyl group, a cyclobutyl group, and a cyclopentyl group. and cyclohexyl groups. In addition, aryl groups having 6 to 13 carbon atoms are also usable. Specific examples of the alkyl group include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. In addition, R 31 ~R 34 The fact that all of the is hydrogen makes it easier to synthesize. This is advantageous in terms of the cost of raw materials.

[0214] Also, Q 1 and Q 2 each independently represents N or CR, R is hydrogen, an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, or a substituent having 6 to 13 carbon atoms; Q represents a substituted or unsubstituted aryl group. 1 and Q 2 At least one of the following is CR Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, and a propyl group. Phenyl, isopropyl, butyl, isobutyl, tert-butyl, n-hexyl Examples of the haloalkyl group having 1 to 6 carbon atoms include at least At least one hydrogen atom is converted by a group 17 element (fluorine, chlorine, bromine, iodine, astatine) Substituted alkyl groups include fluorinated alkyl groups, chlorinated alkyl groups, and brominated alkyl groups. Examples of the fluorinated alkyl group include methyl fluoride, methyl chloride, and fluorinated alkyl groups. Examples of halogen groups include ethyl groups and ethyl chloride groups. The type of each may be one or more. Specific examples of the group include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. Furthermore, the aryl group may have a substituent, and the above-mentioned substituent The groups may be bonded to each other to form a ring. The substituents include alkyl groups having 1 to 6 carbon atoms. A cycloalkyl group having 3 to 6 carbon atoms, or an aryl group having 6 to 13 carbon atoms may also be substituted. Specific examples of the alkyl group having 1 to 6 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl Examples of the aryl group include a cycloalkyl group having 3 to 6 carbon atoms, and a n-hexyl group. Specific examples of the alkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cycloalkyl group. Examples of the aryl group having 6 to 13 carbon atoms include cyclohexyl and the like. Specific examples of the aryl group include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. It is possible.

[0215] Also, Ar 11 and R 31 ~R 34 an aryl group represented by R, an aryl group represented by R 31 ~R 34 At least one of them has a cyano group.

[0216] In addition, in the case of an iridium complex that can be suitably used for the light-emitting element of one embodiment of the present invention, The 4H-triazole ligand has a high triplet excitation energy level. This is particularly suitable for light emitting elements that emit high energy light such as blue light. The iridium complex is preferably represented by the following general formula (G13): It is an iridium complex that is

[0217] [ka]

[0218] In the above general formula (G13), Ar 11 is a substituted or unsubstituted aryl group having 6 to 13 carbon atoms. The aryl group having 6 to 13 carbon atoms includes a phenyl group, a naphthyl group, Specific examples of the aryl group include a biphenyl group and a fluorenyl group. When the group has a substituent, the substituent is an alkyl group having 1 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 the following: Methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert n-butyl group, n-hexyl group, etc. Specific examples of the alkyl group include a cyclopropyl group, a cyclobutyl group, and a cyclopentyl group. and cyclohexyl groups. In addition, aryl groups having 6 to 13 carbon atoms are also usable. Specific examples of the alkyl group include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. Some examples include:

[0219] Also, R 31 ~R 34 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, Cycloalkyl groups having 3 to 6 carbon atoms, substituted or unsubstituted aryl groups having 6 to 13 carbon atoms or a cyano group. Specific examples of the alkyl group having 1 to 6 carbon atoms include Methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert n-butyl group, n-hexyl group, etc. Specific examples of the alkyl group include a cyclopropyl group, a cyclobutyl group, and a cyclopentyl group. and cyclohexyl groups. In addition, aryl groups having 6 to 13 carbon atoms are also usable. Specific examples of the alkyl group include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. In addition, R 31 ~R 34 The fact that all of the is hydrogen makes it easier to synthesize. This is advantageous in terms of the cost of raw materials.

[0220] Also, R 35 is hydrogen, an alkyl group having 1 to 6 carbon atoms, or a haloalkyl group having 1 to 6 carbon atoms. group, or a substituted or unsubstituted aryl group having 6 to 13 carbon atoms. Specific examples of the alkyl group having a number of 1 to 6 include a methyl group, an ethyl group, a propyl group, an isopropyl group, and an ethyl group. Examples include propyl, butyl, isobutyl, tert-butyl, and n-hexyl groups. The haloalkyl group having 1 to 6 carbon atoms may be selected from the group consisting of at least one hydrogen atom and at least one aryl group. Al in which the nitrogen is replaced by a group 17 element (fluorine, chlorine, bromine, iodine, astatine) alkyl groups, such as alkyl fluorides, alkyl chlorides, alkyl bromides, and alkyl iodides; Specifically, methyl fluoride group, methyl chloride group, ethyl fluoride group, chloride The number or type of halogen elements contained in each group is The aryl group having 6 to 13 carbon atoms may be one or more. Specific examples include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. Furthermore, the aryl group may have a substituent, and the substituents may be bonded to each other. The substituent may be an alkyl group having 1 to 6 carbon atoms, a group having 3 carbon atoms, or a group having 4 to 6 carbon atoms. A cycloalkyl group having 6 to 6 carbon atoms or an aryl group having 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 and an ethyl group. , propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, n-hexane Examples of the cycloalkyl group having 3 to 6 carbon atoms include a xyl group. Specifically, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group 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.

[0221] Also, Ar 11 and R 31 ~R 35 and R 31 ~R 34 Few At least one of them has a cyano group.

[0222] In addition, in the case of an iridium complex that can be suitably used for the light-emitting element of one embodiment of the present invention, By having an imidazole skeleton as a ligand, it has a high triplet excited energy level. This can be particularly suitably used for light emitting elements that emit high energy light such as blue light. The iridium complex is preferably represented by the following general formula (G14): It is an iridium complex.

[0223] [ka]

[0224] In the above general formula (G14), Ar 11 is a substituted or unsubstituted aryl group having 6 to 13 carbon atoms. The aryl group having 6 to 13 carbon atoms includes a phenyl group, a naphthyl group, Specific examples of the aryl group include a biphenyl group and a fluorenyl group. When the group has a substituent, the substituent is an alkyl group having 1 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 the following: Methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert n-butyl group, n-hexyl group, etc. Specific examples of the alkyl group include a cyclopropyl group, a cyclobutyl group, and a cyclopentyl group. and cyclohexyl groups. In addition, aryl groups having 6 to 13 carbon atoms are also usable. Specific examples of the alkyl group include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. Some examples include:

[0225] Also, R 31 ~R 34 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, Cycloalkyl groups having 3 to 6 carbon atoms, or substituted or unsubstituted aryl groups having 6 to 13 carbon atoms. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, Ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl and n-hexyl groups. Cycloalkyl groups having 3 to 6 carbon atoms are also examples. Specific examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cycloalkyl group. Examples of the aryl group having 6 to 13 carbon atoms include: Specific examples include phenyl, naphthyl, biphenyl, and fluorenyl groups. In addition, R 31 ~R 34 The fact that all the components are hydrogen makes it easier to synthesize and cheaper to use as raw materials. It is advantageous in terms of rank.

[0226] Also, R 35 and R 36 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 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, and an aryl group. ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, n-hexyl group, etc. Also, haloalkyl groups having 1 to 6 carbon atoms, At least one hydrogen atom is a group 17 element (fluorine, chlorine, bromine, iodine, astatine, etc.). alkyl groups substituted with fluorinated alkyl groups, chlorinated alkyl groups, brominated alkyl groups, Examples of the alkyl group include alkyl groups and iodinated alkyl groups. Specifically, examples of the alkyl groups include methyl fluoride and methyl chloride. Examples of halogen groups include ethyl groups, ethyl fluoride groups, and ethyl chloride groups. The number or type of atoms may be one or more. The aryl group of 3 is a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, etc. Specific examples include the following. Furthermore, the aryl group may have a substituent. The substituents may be bonded to each other to form a ring. an alkyl group having from 1 to 6 carbon atoms, a cycloalkyl group having from 3 to 6 carbon atoms, or an aryl group having from 6 to 13 carbon atoms; A alkyl group having 1 to 6 carbon atoms can also be selected as a substituent. Specifically, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl group, n-hexyl group, etc. Specific examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclopentyl group. Examples of the aryl group include aryl groups having 6 to 13 carbon atoms. Specific examples of the alkyl group include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. It can be mentioned as follows.

[0227] Also, Ar 11 and R 31 ~R 36 An aryl group represented by R 31 ~R 34 At least The other has a cyano group.

[0228] In addition, in the case of an iridium complex that can be suitably used for the light-emitting element of one embodiment of the present invention, The aryl group bonded to the nitrogen of the nitrogen-containing five-membered heterocyclic skeleton is a substituted or unsubstituted phenyl. In the case of a group, it can be vacuum-deposited at a relatively low temperature and has a high triplet excitation energy level. Therefore, it can be suitably used in light-emitting elements that emit high-energy light, such as blue light. The iridium complex is preferably an iridium complex represented by the following general formulas (G15) and (G16). It is a nium complex.

[0229] [ka]

[0230] In the above general formula (G15), R 37 and R 41 represents an alkyl group having 1 to 6 carbon atoms; Represents R 37 and R 41 have the same structure. As an alkyl group having 1 to 6 carbon atoms, Specifically, the alkyl group includes a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and an isopropyl group. Examples of the alkyl group include an n-butyl group, an n-butyl group, and an n-hexyl group.

[0231] Also, R 38 ~R 40 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 prime numbers, a substituted or unsubstituted phenyl group, or a cyano group; Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group and an ethyl group. , propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, n-hexane Examples of cycloalkyl groups having 3 to 6 carbon atoms include cycloalkyl groups such as Specifically, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl R 38 ~R 40 At least one of the groups has a cyano group. It is preferable to do so.

[0232] Also, R 31 ~R 34 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, Cycloalkyl groups having 3 to 6 carbon atoms, or substituted or unsubstituted aryl groups having 6 to 13 carbon atoms. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, Ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl and n-hexyl groups. Cycloalkyl groups having 3 to 6 carbon atoms are also examples. Specific examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cycloalkyl group. Examples of the aryl group having 6 to 13 carbon atoms include: Specific examples include phenyl, naphthyl, biphenyl, and fluorenyl groups. In addition, R 31~R 34 The fact that all the components are hydrogen makes it easier to synthesize and cheaper to use as raw materials. It is advantageous in terms of rank.

[0233] Also, R 35 is hydrogen, an alkyl group having 1 to 6 carbon atoms, or a haloalkyl group having 1 to 6 carbon atoms. group, or a substituted or unsubstituted aryl group having 6 to 13 carbon atoms. Specific examples of the alkyl group having a number of 1 to 6 include a methyl group, an ethyl group, a propyl group, an isopropyl group, and an ethyl group. Examples include propyl, butyl, isobutyl, tert-butyl, and n-hexyl groups. The haloalkyl group having 1 to 6 carbon atoms may be selected from the group consisting of at least one hydrogen atom and at least one aryl group. Al in which the nitrogen is replaced by a group 17 element (fluorine, chlorine, bromine, iodine, astatine) alkyl groups, such as alkyl fluorides, alkyl chlorides, alkyl bromides, and alkyl iodides; Specifically, methyl fluoride group, methyl chloride group, ethyl fluoride group, chloride The number or type of halogen elements contained in each group is The aryl group having 6 to 13 carbon atoms may be one or more. Specific examples include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. Furthermore, the aryl group may have a substituent, and the substituents may be bonded to each other. The substituent may be an alkyl group having 1 to 6 carbon atoms, a group having 3 carbon atoms, or a group having 4 to 6 carbon atoms. A cycloalkyl group having 6 to 6 carbon atoms or an aryl group having 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 and an ethyl group. , propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, n-hexane Examples of the cycloalkyl group having 3 to 6 carbon atoms include a xyl group. Specifically, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group 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.

[0234] [ka]

[0235] In the above general formula (G16), R 37 and R 41 represents an alkyl group having 1 to 6 carbon atoms; Represents R 37 and R 41 have the same structure. As an alkyl group having 1 to 6 carbon atoms, Specifically, the alkyl group includes a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and an isopropyl group. Examples of the alkyl group include an n-butyl group, an n-butyl group, and an n-hexyl group.

[0236] R 38 ~R 40 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, any one of the cycloalkyl groups of the above to 6, a substituted or unsubstituted phenyl group, or a cyano group; Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, and a propyl group. Phenyl, isopropyl, butyl, isobutyl, tert-butyl, n-hexyl Examples of the cycloalkyl group having 3 to 6 carbon atoms include the following: Examples of such groups include cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl. In addition, R 38 ~R 40 At least one of the groups has a cyano group. is preferred.

[0237] Also, R 31 ~R 34 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, Cycloalkyl groups having 3 to 6 carbon atoms, or substituted or unsubstituted aryl groups having 6 to 13 carbon atoms. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, Ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl and n-hexyl groups. Cycloalkyl groups having 3 to 6 carbon atoms are also examples. Specific examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cycloalkyl group. Examples of the aryl group having 6 to 13 carbon atoms include: Specific examples include phenyl, naphthyl, biphenyl, and fluorenyl groups. In addition, R 31 ~R 34 The fact that all the components are hydrogen makes it easier to synthesize and cheaper to use as raw materials. It is advantageous in terms of rank.

[0238] Also, R 35 and R 36 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 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, and an aryl group. ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, n-hexyl group, etc. Also, haloalkyl groups having 1 to 6 carbon atoms, At least one hydrogen atom is a group 17 element (fluorine, chlorine, bromine, iodine, astatine, etc.). alkyl groups substituted with fluorinated alkyl groups, chlorinated alkyl groups, brominated alkyl groups, Examples of the alkyl group include alkyl groups and iodinated alkyl groups. Specifically, examples of the alkyl groups include methyl fluoride and methyl chloride. Examples of halogen groups include ethyl groups, ethyl fluoride groups, and ethyl chloride groups. The number or type of atoms may be one or more. The aryl group of 3 is a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, etc. Specific examples include the following. Furthermore, the aryl group may have a substituent. The substituents may be bonded to each other to form a ring. an alkyl group having from 1 to 6 carbon atoms, a cycloalkyl group having from 3 to 6 carbon atoms, or an aryl group having from 6 to 13 carbon atoms; A alkyl group having 1 to 6 carbon atoms can also be selected as a substituent. Specifically, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl group, n-hexyl group, etc. Specific examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclopentyl group. Examples of the aryl group include aryl groups having 6 to 13 carbon atoms. Specific examples of the alkyl group include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. It can be mentioned as follows.

[0239] In addition, in the case of an iridium complex that can be suitably used for the light-emitting element of one embodiment of the present invention, The 1H-triazole ligand has a high triplet excitation energy level. Since the luminescence can have a high energy level, it is particularly suitable for light-emitting elements that emit light with high energy such as blue light. The iridium complex is preferably represented by the following general formula (G17) ) and (G18).

[0240] [ka]

[0241] In the above general formula (G17), Ar 11 is a substituted or unsubstituted aryl group having 6 to 13 carbon atoms. The aryl group having 6 to 13 carbon atoms includes a phenyl group, a naphthyl group, Specific examples of the aryl group include a biphenyl group and a fluorenyl group. When the group has a substituent, the substituent is an alkyl group having 1 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 the following: Methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert n-butyl group, n-hexyl group, etc. Specific examples of the alkyl group include a cyclopropyl group, a cyclobutyl group, and a cyclopentyl group. and cyclohexyl groups. In addition, aryl groups having 6 to 13 carbon atoms are also usable. Specific examples of the alkyl group include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. Some examples include:

[0242] Also, R 31 ~R 34 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, Cycloalkyl groups having 3 to 6 carbon atoms, or substituted or unsubstituted aryl groups having 6 to 13 carbon atoms. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, Ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl and n-hexyl groups. Cycloalkyl groups having 3 to 6 carbon atoms are also examples. Specific examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cycloalkyl group. Examples of the aryl group having 6 to 13 carbon atoms include: Specific examples include phenyl, naphthyl, biphenyl, and fluorenyl groups. In addition, R 31 ~R 34 The fact that all the components are hydrogen makes it easier to synthesize and cheaper to use as raw materials. It is advantageous in terms of rank.

[0243] Also, R 36 is hydrogen, an alkyl group having 1 to 6 carbon atoms, or a haloalkyl group having 1 to 6 carbon atoms. group, or a substituted or unsubstituted aryl group having 6 to 13 carbon atoms. Specific examples of the alkyl group having a number of 1 to 6 include a methyl group, an ethyl group, a propyl group, an isopropyl group, and an ethyl group. Examples include propyl, butyl, isobutyl, tert-butyl, and n-hexyl groups. The haloalkyl group having 1 to 6 carbon atoms may be selected from the group consisting of at least one hydrogen atom and at least one aryl group. Al in which the nitrogen is replaced by a group 17 element (fluorine, chlorine, bromine, iodine, astatine) alkyl groups, such as alkyl fluorides, alkyl chlorides, alkyl bromides, and alkyl iodides; Specifically, methyl fluoride group, methyl chloride group, ethyl fluoride group, chloride The number or type of halogen elements contained in each group is The aryl group having 6 to 13 carbon atoms may be one or more. Specific examples include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. Furthermore, the aryl group may have a substituent, and the substituents may be bonded to each other. The substituent may be an alkyl group having 1 to 6 carbon atoms, a group having 3 carbon atoms, or a group having 4 to 6 carbon atoms. A cycloalkyl group having 6 to 6 carbon atoms or an aryl group having 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 and an ethyl group. , propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, n-hexane Examples of the cycloalkyl group having 3 to 6 carbon atoms include a xyl group. Specifically, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group 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.

[0244] Also, Ar 11 , R 31 ~R 34 , and R 36 and R 31 ~R 34 At least one of them has a cyano group.

[0245] [ka]

[0246] In the above general formula (G18), R 37 and R 41 represents an alkyl group having 1 to 6 carbon atoms; Represents R 37 and R 41 have the same structure. As an alkyl group having 1 to 6 carbon atoms, Specifically, the alkyl group includes a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and an isopropyl group. Examples of the alkyl group include an n-butyl group, an n-butyl group, and an n-hexyl group.

[0247] Also, R38 ~R 40 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 prime numbers, a substituted or unsubstituted phenyl group, or a cyano group; Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group and an ethyl group. , propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, n-hexane Examples of cycloalkyl groups having 3 to 6 carbon atoms include cycloalkyl groups such as Specifically, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl R 38 ~R 40 At least one of the groups has a cyano group. It is preferable to do so.

[0248] Also, R 31 ~R 34 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, Cycloalkyl groups having 3 to 6 carbon atoms, or substituted or unsubstituted aryl groups having 6 to 13 carbon atoms. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, Ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl and n-hexyl groups. Cycloalkyl groups having 3 to 6 carbon atoms are also examples. Specific examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cycloalkyl group. Examples of the aryl group having 6 to 13 carbon atoms include: Specific examples include phenyl, naphthyl, biphenyl, and fluorenyl groups. In addition, R 31 ~R 34 The fact that all the components are hydrogen makes it easier to synthesize and cheaper to use as raw materials. It is advantageous in terms of rank.

[0249] Also, R 36 is hydrogen, an alkyl group having 1 to 6 carbon atoms, or a haloalkyl group having 1 to 6 carbon atoms. group, or a substituted or unsubstituted aryl group having 6 to 13 carbon atoms. Specific examples of the alkyl group having a number of 1 to 6 include a methyl group, an ethyl group, a propyl group, an isopropyl group, and an ethyl group. Examples include propyl, butyl, isobutyl, tert-butyl, and n-hexyl groups. The haloalkyl group having 1 to 6 carbon atoms may be selected from the group consisting of at least one hydrogen atom and at least one aryl group. Al in which the nitrogen is replaced by a group 17 element (fluorine, chlorine, bromine, iodine, astatine) alkyl groups, such as alkyl fluorides, alkyl chlorides, alkyl bromides, and alkyl iodides; Specifically, methyl fluoride group, methyl chloride group, ethyl fluoride group, chloride The number or type of halogen elements contained in each group is The aryl group having 6 to 13 carbon atoms may be one or more. Specific examples include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. Furthermore, the aryl group may have a substituent, and the substituents may be bonded to each other. The substituent may be an alkyl group having 1 to 6 carbon atoms, a group having 3 carbon atoms, or a group having 4 to 6 carbon atoms. A cycloalkyl group having 6 to 6 carbon atoms or an aryl group having 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 and an ethyl group. , propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, n-hexane Examples of the cycloalkyl group having 3 to 6 carbon atoms include a xyl group. Specifically, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group 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.

[0250] R in the above general formulae (G12) to (G18) 31 ~R 34 and an alkyl group represented by the formula: The aryl group may be, for example, a group represented by the above structural formulas (R-1) to (R-29). The alkyl and aryl groups that can be used are as follows: Not limited to.

[0251] In the general formulae (G11) to (G14) and (G17), Ar 11 Expressed as and in general formula (G11), Ar 12 The aryl group represented by the formula: For example, the groups represented by the above structural formulas (R-12) to (R-29) can be used. In addition, Ar 11 and Ar 12 The groups that can be used as .

[0252] In addition, R in the general formulae (G15), (G16), and (G18) 37 and R 41 Represented by The alkyl group may be, for example, a group represented by the above structural formulas (R-1) to (R-10). However, the groups that can be used as the alkyl group are not limited to these.

[0253] In addition, R in the general formulae (G15), (G16), and (G18) 38 ~R 40 Represented by The alkyl group or the substituted or unsubstituted phenyl group may be, for example, any one of the above structural formulas (R-1) to (R-2). The group represented by (R-22) can be used. In addition, an alkyl group or a phenyl group The groups that can be used as are not limited to these.

[0254] In addition, R in the above general formulae (G13) to (G16) 35 and general formula (G14), (G1 6) or (G18) R 36 An alkyl group, an aryl group, or a haloalkyl group represented by the following formula: For example, the above structural formulae (R-1) to (R-29) and the following structural formulae (R-30) to (R-31) The group represented by (R-37) can be used. In addition, an alkyl group, an aryl group, or The groups that can be used as the haloalkyl group are not limited to these.

[0255] [ka]

[0256] Specific examples of iridium complexes Specific structures of iridium complexes represented by the above general formulas (G11) to (G18) Examples of the compound include compounds represented by the following structural formulas (500) to (534). The iridium complexes represented by the general formulae (G11) to (G18) are not limited to the following examples. stomach.

[0257] [ka]

[0258] [ka]

[0259] [ka]

[0260] [ka]

[0261] [ka]

[0262] [ka]

[0263] As described above, the iridium complexes exemplified above have relatively low HOMO levels and LU Since the compound has an MO level, it is suitable as a guest material for the light-emitting element of one embodiment of the present invention. This makes it possible to manufacture a light-emitting element with good luminous efficiency. Iridium complexes have a high triplet excited energy level and are therefore particularly useful as blue luminescent elements. This makes it possible to fabricate blue light-emitting devices with good luminous efficiency. In addition, the iridium complexes exemplified above are excellent in resistance to repeated oxidation and reduction. Since the iridium complex has good resistance, the use of the iridium complex in a light-emitting element can improve the operating life. A good light emitting device can be manufactured.

[0264] The light-emitting material contained in the light-emitting layer 130 and the light-emitting layer 135 is a material that emits triplet excited energy. Any material capable of converting triplet excitation energy into light emission may be used. In addition to phosphorescent materials, thermally activated delayed fluorescent materials can be used. The part described as "optical material" may be read as "thermally activated delayed fluorescent material."

[0265] <Host Material 133> The host material 133 has a LUMO level higher than that of the host material 132. and the host material 131 has a HOMO level lower than the HOMO level of the guest material 131. It is preferable to select the material 133, the host material 132, and the guest material 131. As a result, a light-emitting element having high luminous efficiency and driven at a low voltage can be obtained. As the material 133, the materials exemplified as the host material 132 may be used.

[0266] In addition, as the host material 133, a material having a higher electron transporting property than a hole transporting property may be used. Can be done, 1×10 -6 cm 2 It is preferable that the material has an electron mobility of .beta. / Vs or more. Nitrogen-containing heteroaromatic compounds are examples of materials that easily accept electrons (materials with electron transport properties). Compounds with a π-electron deficient heteroaromatic skeleton, such as those described above, and zinc and aluminum-based metals Complexes and the like can be used. Specifically, quinoline ligands, benzoquinoline ligands, Metal complexes with oxazole or thiazole ligands, and oxadiazole Derivatives, triazole derivatives, benzimidazole derivatives, quinoxaline derivatives, dibenzo quinoxaline derivatives, phenanthroline derivatives, pyridine derivatives, bipyridine derivatives, Examples of the compounds include pyrimidine derivatives and triazine derivatives.

[0267] Specifically, for example, tris(8-quinolinolato)aluminum(III) (abbreviation: A lq), tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviation: Al mq 3 ), bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation :BeBq 2), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)a Aluminum(III) (abbreviation: BAlq), bis(8-quinolinolato)zinc(II) (abbreviation: Metal complexes having a quinoline or 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 such as 2-[3-(dibenzothiophen-4-yl)phenyl] Dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-( Dibenzothiophene-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxalate 2-[3'-(9H-carbazole-9-yl) 2mCzBPDB q) 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]di Benzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzo 7mDibenzo[f,h]quinoxaline (abbreviation: 7mDB TPDBq-II) and 6-[3-(dibenzothiophen-4-yl)phenyl]di Benzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 2-[3-(3, 9'-Bi-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (Abbreviation: 2mCzCzPDBq), 4,6-bis[3-(phenanthren-9-yl)phenyl] phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-diphenyl 4,6-zothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), Bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mC Heterocyclic compounds with diazine skeletons such as 2-{4-[3-(N-phenyl 9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}- Triazines such as 4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn) Heterocyclic compounds with an aryl skeleton and 3,5-bis[3-(9H-carbazol-9-yl] )phenyl]pyridine (abbreviation: 35DCzPPy), 1,3,5-tri[3-(3-pyridyl Heterocyclization of pyridine skeletons such as TmPyPB Compound 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: Among the above-mentioned heterocyclic compounds, heteroaromatic compounds such as BzOs can also be used. The triazine skeleton, the diazine skeleton (pyrimidine, pyrazine, pyridazine), and the pyrimidine skeleton are also Heterocyclic compounds having at least one diamine skeleton are preferred because they are stable and have good reliability. In addition, the heterocyclic compound having the skeleton has high electron transport properties and contributes to reducing the driving voltage. In addition, poly(2,5-pyridinediyl) (abbreviation: PPy), poly[(9,9-dihexyl) PF -Py), poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2 PF-BPy) The substances mentioned here are mainly 1×10 -6 cm 2 / Vs or more In addition, as long as the material has a higher electron transporting property than the hole transporting property, The following substances may be used.

[0268] As the host material 133, the following hole transporting materials can be used.

[0269] As the hole transporting material, a material having a higher hole transporting property than an electron transporting property can be used. ×10 -6 cm 2 It is preferable that the material has a hole mobility of 1 / Vs or more. The compounds are made using aromatic amines, carbazole derivatives, aromatic hydrocarbons, stilbene derivatives, etc. The hole transporting material may be a polymer compound.

[0270] As the material having high hole transport properties, specifically, aromatic amine compounds include N, N'-Di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DT DPPA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenyla N,N'-bis{4-[bis(3-methylphenyl) {N,N'-diphenyl-(1,1'-biphenyl)-4,4' -diamine (abbreviation: DNTPD), 1,3,5-tris[N-(4-diphenylamino [phenyl]-N-phenylamino]benzene (abbreviation: DPA3B), etc. .

[0271] Specific examples of carbazole derivatives include 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 [N-(1-naphthyl)amino]-9-phenylcarbazole (abbreviation :PCzTPN2), 3-[N-(9-phenylcarbazol-3-yl)-N-phenyl 3,6-bis[N- (9-Phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazol PCzPCA2, 3-[N-(1-naphthyl)-N-(9-phenylcarbazone] carbazol-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1) etc. can be mentioned.

[0272] Another example of a carbazole derivative is 4,4'-di(N-carbazolyl)biphene. Nyl (abbreviation: CBP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzoyl Zene (abbreviation: TCPB), 9-[4-(10-phenyl-9-anthryl)phenyl]- 9H-Carbazole (abbreviation: CzPA), 1,4-bis[4-(N-carbazolyl)phenyl] nyl)-2,3,5,6-tetraphenylbenzene and the like can be used.

[0273] As the aromatic hydrocarbon, for example, 2-tert-butyl-9,10-di(2- naphthyl)anthracene (abbreviation: t-BuDNA), 2-tert-butyl-9,10- Di(1-naphthyl)anthracene, 9,10-bis(3,5-diphenylphenyl)anthracene DPPA, 2-tert-butyl-9,10-bis(4-phenylphenyl) 9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDBA), Helical (abbreviation: DNA), 9,10-diphenylanthracene (abbreviation: DPAnth), 2-tert-Butylanthracene (abbreviation: t-BuAnth), 9,10-bis(4- Methyl-1-naphthyl)anthracene (abbreviation: DMNA), 2-tert-butyl-9, 10-Bis[2-(1-naphthyl)phenyl]anthracene, 9,10-bis[2-(1 -naphthyl)phenyl]anthracene, 2,3,6,7-tetramethyl-9,10-di( 1-naphthyl)anthracene, 2,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene 9,9'-bianthryl, 10,10'-diphenyl-9,9'- Bianthryl, 10,10'-bis(2-phenylphenyl)-9,9'-bianthryl , 10,10'-bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9' -Bianthryl, anthracene, tetracene, rubrene, perylene, 2,5,8,11- Tetra(tert-butyl)perylene, etc. In addition, pentacene, coro Years and years can also be used. In this way, 1×10 -6 cm 2 Hole mobility above / Vs It is more preferable to use an aromatic hydrocarbon having 14 to 42 carbon atoms.

[0274] 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.

[0275] In addition, poly(N-vinylcarbazole) (abbreviation: PVK) and poly(4-vinyltriphenylphosphine) 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 Polymer compounds such as Poly(phenyl)benzidine (abbreviation: Poly-TPD) can also be used. can.

[0276] Furthermore, examples of materials with high hole transport properties include 4,4'-bis[N-(1-naphthalene) N,N'-phenylamino]biphenyl (abbreviation: NPB or α-NPD) 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-naphthalene 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' -bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 4 -Phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylphosphine mBPAFLP, N-(9,9-dimethyl-9H-fluorene-2 -yl)-N-{9,9-dimethyl-2-[N'-phenyl-N'-(9,9-dimethyl -9H-fluoren-2-yl)amino]-9H-fluoren-7-yl}phenylamino DFLADFL, N-(9,9-dimethyl-2-diphenylamino-9H- Fluoren-7-yl)diphenylamine (abbreviation: DPNF), 2-[N-(4-diphenyl N-phenylaminophenyl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation: DPASF), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl) Triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9- Phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1B) P), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl) Triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''- (9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBN BB), 4-phenyldiphenyl-(9-phenyl-9H-carbazol-3-yl)a 1BP, N,N'-bis(9-phenylcarbazol-3-yl) -N,N'-diphenylbenzene-1,3-diamine (abbreviation: PCA2B), N,N', N''-Triphenyl-N,N',N''-tris(9-phenylcarbazole-3-yl) N-(4-biphenyl)benzene-1,3,5-triamine (abbreviation: PCA3B) -N-(9,9-dimethyl-9H-fluoren-2-yl)-9-phenyl-9H-carbazone PCBiF, N-(1,1'-biphenyl-4-yl) -N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-di Methyl-9H-fluoren-2-amine (abbreviation: PCBBiF), 9,9-dimethyl-N -phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl] PCBAF, N-phenyl-N-[4-(9-phenyl -9H-carbazol-3-yl)phenyl]spiro-9,9'-bifluorene-2-a PCBASF, 2-[N-(9-phenylcarbazol-3-yl)-N -phenylamino]spiro-9,9'-bifluorene (abbreviation: PCASF), 2,7-bi 9,9'-[N-(4-diphenylaminophenyl)-N-phenylamino]spiro Bifluorene (abbreviation: DPA2SF), N-[4-(9H-carbazol-9-yl)fluorene N,N'-phenyl]-N-(4-phenyl)phenylaniline (abbreviation: YGA1BP), Bis[4-(carbazol-9-yl)phenyl]-N,N'-diphenyl-9,9-di Aromatic amine compounds such as methylfluorene-2,7-diamine (abbreviation: YGA2F) Also, 3-[4-(1-naphthyl)-phenyl]-9-phenyl can be used. -9H-Carbazole (abbreviation: PCPN), 3-[4-(9-phenanthryl)-phenyl PCPPn, 3,3'-bis(9-phenyl-9H-carbazole phenyl-9H-carbazole) (abbreviation: PCCP), 1,3-bis(N-carbazolyl )benzene (abbreviation: mCP), 3,6-bis(3,5-diphenylphenyl)-9-phenyl Nylcarbazole (abbreviation: CzTP), 3,6-di(9H-carbazol-9-yl)- 9-Phenyl-9H-carbazole (abbreviation: PhCzGI), 2,8-di(9H-carbazole) 4-{3-[3-( 9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation Name: mmDBFFLBi-II), 4,4',4''-(benzene-1,3,5-triyl 1,3,5-tri(dibenzofuran) (abbreviation: DBF3P-II), 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-fluorene-9- 4-phenyl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), -[3-(triphenylen-2-yl)phenyl]dibenzothiophene (abbreviation: mDBT PTp-II) and other amine compounds, carbazole compounds, thiophene compounds, and furan compounds Compounds such as fluorene compounds, triphenylene compounds, and phenanthrene compounds can be used. Among the above-mentioned compounds, those having a pyrrole skeleton, a furan skeleton, a thiophene skeleton, and A compound having at least one aromatic amine skeleton is preferred because it is stable and has good reliability. In addition, the compound having this skeleton has high hole transporting properties and contributes to reducing the driving voltage.

[0277] The light-emitting layer 130 and the light-emitting layer 135 may be composed of two or more layers. For example, the first light-emitting layer and the second light-emitting layer may be laminated in this 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 transport properties as a host material for the first light-emitting layer and a material having an electron transporting property is used as a host material for the second light-emitting layer. In addition, the light-emitting material contained in the first light-emitting layer and the second light-emitting layer may be the same material. The materials may be different, and may be materials that have the same color emission function. The material may have a function of emitting light of different colors. By using luminescent materials each having the function of emitting light, multiple lights can be obtained simultaneously. In particular, the two light-emitting layers can be used to produce white light. It is preferable to select a light-emitting material that has a high luminescence property.

[0278] In addition, in the light-emitting layer 130, materials other than the host material 132 and the guest material 131 are In the light-emitting layer 135, the host material 133 and the host material 132 may be included. , and may contain materials other than the guest material 131.

[0279] The light-emitting layers 130 and 135 can be formed by deposition (including vacuum deposition), ink-jet deposition, etc. The material can be formed by a method such as a printing method, a coating method, a gravure printing method, etc. , quantum dots, and other inorganic compounds or polymer compounds (oligomers, dendrimers, polymers - etc.).

[0280] Quantum dots Quantum dots are semiconductor nanocrystals with sizes ranging from a few nm to a few tens of nm, with a size of 1×10 3 From pcs 1×10 6 Quantum dots are composed of about 100 atoms. The energy of quantum dots depends on their size. Therefore, even if quantum dots are made of the same material, the emission wavelengths change depending on the size. Therefore, by changing the size of the quantum dots used, light emission can be easily The wavelength can be changed.

[0281] In addition, quantum dots have a narrow emission spectrum peak width, so they can emit light with good color purity. Furthermore, the theoretical internal quantum efficiency of quantum dots is said to be 100%. This is much higher than 25% of organic compounds that exhibit fluorescence, and 15% of organic compounds that exhibit phosphorescence. This means that by using quantum dots as a light-emitting material, It is possible to obtain a light-emitting element with high luminous efficiency. Since the inherent stability of the material is also excellent, it is possible to obtain a light-emitting element that is favorable in terms of life. can.

[0282] The materials that make up quantum dots include elements from Group 14, Group 15, Group 16, and Compounds consisting of a number of group 14 elements, and compounds consisting of elements belonging to groups 4 to 14 and group 16 elements Compounds, compounds of Group 2 elements and Group 16 elements, compounds of Group 13 elements and Group 15 elements , compounds of Group 13 and Group 17 elements, compounds of Group 14 and Group 15 elements, Compounds of group 11 and group 17 elements, iron oxides, titanium oxides, chalcogenide spinel Examples of the semiconductor clusters include various semiconductor clusters.

[0283] Specifically, cadmium selenide, cadmium sulfide, cadmium telluride, and sulfur selenide Lead, zinc oxide, zinc sulfide, zinc telluride, mercury sulfide, mercury selenide, mercury telluride, arsenide Indium, indium phosphide, gallium arsenide, gallium phosphide, indium nitride, nitride Gallium, indium antimonide, gallium antimonide, aluminum phosphide, arsenide Aluminum, Aluminum antimonide, Lead selenide, Lead telluride, Lead sulfide, Lead selenide Indium, indium telluride, indium sulfide, gallium selenide, arsenic sulfide, selenium arsenic nitride, arsenic telluride, antimony sulfide, antimony selenide, antimony telluride, Bismuth sulfide, bismuth selenide, bismuth telluride, silicon, silicon carbide, germanium Aluminum, tin, selenium, tellurium, boron, carbon, phosphorus, boron nitride, boron phosphide, boron arsenide , aluminum nitride, aluminum sulfide, barium sulfide, barium selenide, barium telluride Lithium, 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, acid Nickel oxide, cobalt oxide, cobalt sulfide, iron oxide, iron sulfide, manganese oxide, molyb sulfide tantalum oxide, titanium oxide, zirconium oxide, vanadium oxide, tungsten oxide, tantalum oxide Aluminum, silicon nitride, germanium nitride, aluminum oxide, barium titanate, selenium and zinc Compounds of lead and cadmium, compounds of indium, arsenic and phosphorus, compounds of cadmium, selenium and sulfur Compounds of cadmium, selenium and tellurium, compounds of indium, gallium and arsenic , compounds of indium, gallium and selenium, compounds of indium, selenium and sulfur, compounds of copper and indium Examples of the compounds include indium and sulfur compounds, and combinations of these. In addition, the composition is expressed in any ratio, so-called alloy type quantum dots can be used. For example, alloy quantum dots of cadmium, selenium, and sulfur can be fabricated by changing the ratio of the elements. This is one of the effective methods to obtain blue light emission because the emission wavelength can be changed by It is one.

[0284] Quantum dot structures include core type, core-shell type, and core-multishell type. Either of these can be used, but it is also advisable to cover the core with another inorganic material with a wider band gap. By forming a shell of material, defects and dangling bonds on the nanocrystal surface can be eliminated. This greatly improves the quantum efficiency of light emission, It is preferable to use core-shell or core-multishell quantum dots. Examples of materials include zinc sulfide and zinc oxide.

[0285] In addition, quantum dots have a high proportion of surface atoms, making them highly reactive and less prone to aggregation. Therefore, a protective agent or a protective group is attached to the surface of the quantum dots. It is preferable that the protecting agent is attached or the protecting group is provided. It is possible to prevent aggregation and increase solubility in solvents. It is also possible to reduce reactivity and electrically It is also possible to improve stability. Examples of the protecting agent (or protecting group) include poliovirus. Polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene Polyoxyethylene alkyl ethers such as ethylene oleyl ether, tripropyl phosphatase phosphine, tributylphosphine, trihexylphosphine, trioctylphosphine, etc. Trialkylphosphines, polyoxyethylene n-octylphenyl ether, polyoxyethylene Polyoxyethylene alkylphenyl ethers such as oxyethylene n-nonylphenyl ether amine, tri(n-hexyl)amine, tri(n-octyl)amine, tri(n-decyl)amine ) tertiary amines such as amine, tripropylphosphine oxide, tributylphosphine Oxide, trihexylphosphine oxide, trioctylphosphine oxide, tridecylphosphine oxide Organic phosphorus compounds such as silylphosphine oxide, polyethylene glycol dilaurate, polyethylene glycol diesters such as polyethylene glycol distearate, Organic nitrogen compounds such as pyridine, lutidine, collidine, quinolines, and other nitrogen-containing aromatic compounds , hexylamine, octylamine, decylamine, dodecylamine, tetradecylamine aminoalkanes such as dibutylsulfide, hexadecylamine, and octadecylamine; dialkyl sulfides such as dimethyl sulfoxide and dibutyl sulfoxide; organic sulfur compounds such as alkyl sulfoxides, sulfur-containing aromatic compounds such as thiophene, palmitic acid compounds, etc. Higher fatty acids such as acetic acid, stearic acid, and oleic acid, alcohols, sorbitan fatty acid esters, esters, fatty acid modified polyesters, tertiary amine modified polyurethanes, polyethylene Examples of such compounds include amines.

[0286] As quantum dots become smaller, their band gaps become larger, so the desired wavelengths can be obtained. The size of the crystal is adjusted accordingly to obtain long-range light. As a result, the emission of quantum dots is shifted to the blue side, i.e., to the higher energy side. By changing the size of the filter, wavelengths in the ultraviolet, visible, and infrared regions of the spectrum can be obtained. The emission wavelength can be tuned over a range of wavelengths. The size (diameter) of the quantum dot is A range of 0.5 nm to 20 nm, preferably 1 nm to 10 nm, is usually used. In addition, the narrower the size distribution of quantum dots, the narrower the emission spectrum becomes and the higher the color purity becomes. The shape of the quantum dots is not particularly limited, and may be spherical, The quantum dots may be rod-shaped, disk-shaped, or have other shapes. Since quantum rods have the function of producing directional light, the use of quantum rods as light-emitting materials As a result, a light emitting element having better external quantum efficiency can be obtained.

[0287] In most cases, organic EL devices are made by dispersing a light-emitting material in a host material. The host material is one of the most important materials for the luminescence. The material must have a singlet or triplet excited energy level. In particular, when a blue phosphorescent material is used as the light-emitting material, triplet excitation of A host material that has the energy level and is excellent in terms of life is required, and its development is Here, quantum dots emit light by themselves without using a host material. Even if a layer is formed, the luminous efficiency can be maintained, which is also preferable from the viewpoint of life. When the light-emitting layer is formed only with quantum dots, The core-shell structure (including a core-multishell structure) is preferred.

[0288] When quantum dots are used as the light-emitting material of the light-emitting layer, the thickness of the light-emitting layer is 3 nm to 100 nm. m, preferably 10 nm to 100 nm, and the content of quantum dots in the light-emitting layer is 1 to 1 00% by volume. However, it is preferable to form the light-emitting layer only from quantum dots. In the case where the quantum dots are dispersed in a host as a light-emitting material to form a light-emitting layer, the host material The quantum dots are dispersed in a suitable liquid medium, or the host material and the quantum dots are dissolved or mixed in a suitable liquid medium. Disperse and apply wet processes (spin coating, casting, die coating, blade coating, etc.) Coating method, roll coating method, inkjet method, printing method, spray coating method, curtain coating The phosphorescent material may be formed by a method such as the Langmuir-Blodgett method. For the light-emitting layer using the above, in addition to the wet process, a vacuum deposition method can also be suitably used. This can be done.

[0289] Examples of liquid media used in wet processes include methyl ethyl ketone, cyclohexane, etc. Ketones such as xanone, fatty acid esters such as ethyl acetate, halogens such as dichlorobenzene Hydrocarbons, aromatics such as toluene, xylene, mesitylene, and cyclohexylbenzene Hydrocarbons, aliphatic hydrocarbons such as cyclohexane, decalin, and dodecane, dimethylformamide, etc. Organic solvents such as dichloromethane (DMF) and dimethyl sulfoxide (DMSO) can be used. Cut.

[0290] <Hole injection layer> The hole injection layer 111 is configured to inject holes from one of the pair of electrodes (electrode 101 or electrode 102). It has the function of promoting hole injection by reducing the injection barrier. It is formed by phthalocyanine derivatives or aromatic amines. Transition metal oxides and Examples include molybdenum oxide, vanadium oxide, ruthenium oxide, and tungsten oxide. , manganese oxide, etc. Phthalocyanine derivatives include phthalocyanine, Examples of aromatic amines include benzidine derivatives and phenyl Diamine derivatives, etc. Polymer compounds such as polythiophene and polyaniline It is also possible to use self-doped polythiophenes, such as poly(ethylenediamine). Representative examples include poly(oxythiophene) / poly(styrenesulfonic acid).

[0291] The hole injection layer 111 is made of a compound of a hole transporting material and a material that has an electron accepting property. Alternatively, a layer containing a material exhibiting electron accepting properties and a layer containing a positive electrode may be used. A stack of layers containing hole transporting materials may also be used. It is possible to give and receive electric charges in the presence of a magnetic field. Materials that exhibit electron-accepting properties include quinodimethane. Organic acceptors such as aryl, chloranil, and hexaazatriphenylene derivatives Specifically, 7,7,8,8-tetracyano-2,3,5,6- Tetrafluoroquinodimethane (abbreviation: F 4 -TCNQ), chloranil, 2,3,6,7, 10,11-Hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation These are compounds that have electron-withdrawing groups (halogen groups or cyano groups) such as aryloxycarbonyl (HAT-CN). In addition, transition metal oxides, for example oxides of metals in Groups 4 to 8, can be used. In particular, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, and oxide These include tungsten oxide, manganese oxide, and rhenium oxide. Among these, molybdenum oxide is Among these, it is preferred because it is stable, has low hygroscopicity, and is easy to handle.

[0292] As the hole transporting material, a material having a higher hole transporting property than an electron transporting property can be used. ×10 -6 cm 2 It is preferable that the material has a hole mobility of 1 / Vs or more. The aromatic amines and carbazoles mentioned above as hole transport materials that can be used in the light emitting layer are The hole transport layer may be a hole transport layer having a hole transporting property. The transport material may be a polymeric compound.

[0293] <Hole transport layer> The hole transport layer 112 is a layer containing a hole transporting material. The hole transporting layer 112 is connected to the hole injection layer 111. The highest occupied molecular orbital of the hole injection layer 111 is used to transport the injected holes to the light emitting layer. (Highest Occupied Molecular Orbital, HOMO It is preferable that the HOMO level be the same as or close to the HOMO level (also referred to as the HOMO level).

[0294] Also, 1×10 -6 cm 2 It is preferable that the material has a hole mobility of at least 1 / Vs. However, other substances may be used as long as they have a higher hole transporting property than an electron transporting property. The layer containing a substance having a high hole transporting property may be a single layer or a double layer of the above substance. More than one layer may be laminated.

[0295] ≪Electron transport layer≫ The electron transport layer 118 is connected to the other of the pair of electrodes (electrode 101 or It has the function of transporting electrons injected from the electrode 102) to the light-emitting layer. can use materials with higher electron transport properties than holes, and the -6 cm 2 / Vs It is preferable that the material has an electron mobility of at least 100 nm. As materials with electron transport properties, π-electron deficient heteroaromatic compounds such as nitrogen-containing heteroaromatic compounds are Aromatic compounds and metal complexes can be used. Specifically, The quinoline ligand, benzoquinoline ligand, and oxazole ligand mentioned above as electron transport materials that can be used Ligands, or metal complexes with thiazole ligands, oxadiazole derivatives, triazole azole derivatives, benzimidazole derivatives, quinoxaline derivatives, dibenzoquinoxaline Derivatives, phenanthroline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives and triazine derivatives. -6 cm 2 / Vs or more It is preferable that the material has a higher electron transporting property than a hole transporting property. If desired, a material other than the above may be used for the electron transport layer. The layer may be not only a single layer, but also two or more layers made of the above-mentioned substances may be laminated.

[0296] In addition, 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 type of structure prevents electrons from penetrating the light-emitting layer. This is highly effective in suppressing problems that arise from the above (for example, a decrease in element life).

[0297] Alternatively, an n-type compound semiconductor may be used, such as titanium oxide, zinc oxide, or silicon oxide. tin oxide, tungsten oxide, tantalum oxide, barium titanate, barium zirconate , zirconium oxide, hafnium oxide, aluminum oxide, yttrium oxide, disilicic acid Oxides such as zinc oxide, nitrides such as silicon nitride, cadmium sulfide, zinc selenide and zinc sulfide, etc. can also be used.

[0298] ≪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 In addition, the above-mentioned electron transporting material and the corresponding electron A composite material of a material exhibiting electron donating properties can also be used. Examples of the metal include Group 1 metals, Group 2 metals, and oxides thereof. Lithium fluoride, sodium fluoride, cesium fluoride, calcium fluoride, lithium Use of alkali metals, alkaline earth metals, or compounds thereof, such as oxides, etc. Also, rare earth metal compounds such as erbium fluoride can be used. In addition, an electride may be used for the electron injection layer 119. Examples of the electride include For example, a material in which electrons are highly concentrated in a mixed oxide of calcium and aluminum can be mentioned. In addition, the electron injection layer 119 may be formed using a material that can be used in the electron transport layer 118. good.

[0299] In addition, the electron injection layer 119 is made of a composite material obtained by mixing an organic compound and an electron donor. Such composite materials may be made by adding electrons to an organic compound via an electron donor. In this case, the organic compound is It is preferable that the material has excellent transport properties for the generated electrons. Specifically, for example, the above-mentioned The material constituting the electron transport layer 118 (metal complex, heteroaromatic compound, etc.) can be used. The electron donor may be any substance that exhibits electron donating properties to organic compounds. For the metal, alkali metals, alkaline earth metals and rare earth metals are preferred, and lithium, sodium , cesium, magnesium, calcium, erbium, ytterbium, etc. In addition, alkali metal oxides and alkaline earth metal oxides are preferred, and lithium oxide, calcium oxide, etc. Examples of the oxides include magnesium oxide, barium oxide, etc. A base can also be used. In addition, organic compounds such as tetrathiafulvalene (TTF) can be used. You can also use things.

[0300] The above-mentioned light-emitting layer, hole injection layer, hole transport layer, electron transport layer, and electron injection layer are These methods include deposition (including vacuum deposition), inkjet, coating, and gravure printing. The light-emitting layer, the hole-injecting layer, the hole-transporting layer, the electron In addition to the above-mentioned materials, the transport layer and the electron injection layer may be made of inorganic compounds such as quantum dots or high molecular weight compounds. A polymer compound (oligomer, dendrimer, polymer, etc.) may also be used.

[0301] 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 of these. It can be formed using the above.

[0302] 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 composite material containing Al. Examples of alloys containing Al include Al and L (L is titanium (Ti), neodymium (Nd)). (representing one or more of Nd, Ni, and La) Examples of the alloy include an alloy containing Al and Ti, or an alloy containing Al, Ni and La. Aluminum has low resistance and high light reflectance. Since aluminum is abundant and inexpensive, the manufacturing cost of light-emitting elements using aluminum is low. In addition, silver (Ag) or Ag and N (N is yttrium ( Y), Nd, Magnesium (Mg), Ytterbium (Yb), Al, Ti, Gallium ( Ga), zinc (Zn), indium (In), tungsten (W), manganese (Mn), Tin (Sn), iron (Fe), Ni, copper (Cu), palladium (Pd), iridium (Ir ), or an alloy containing gold (Au), etc. Examples of alloys that can be used include alloys containing silver, palladium, and copper, alloys containing silver and copper, and alloys containing silver and magnesium. Alloys containing nesium, alloys containing silver and nickel, alloys containing silver and gold, and silver and ytterbium Other examples include alloys containing tungsten, chromium (Cr), molybdenum (Mo ), copper, titanium, and other transition metals can be used.

[0303] The light emitted from the light-emitting layer is emitted through one or both of the electrodes 101 and 102. Therefore, at least one of the electrodes 101 and 102 is transparent to light. It is preferable that the conductive material is made of a conductive material having a function of transmitting visible light. The light transmittance is 40% or more and 100% or less, preferably 60% or more and 100% or less, and Its resistivity is 1×10 -2 Examples include conductive materials with a resistance of Ω·cm or less.

[0304] In addition, the electrodes 101 and 102 have a function of transmitting light and a function of reflecting light. The conductive material may be formed of a conductive material having a visible light reflectance of 20 or more. % or more and 80% or less, preferably 40% or more and 70% or less, and the resistivity is 1×10 -2 Conductive materials with a capacitance of Ω·cm or less include conductive metals, alloys, and conductive materials. The insulating layer can be formed by using one or more of the following compounds: Indium Tin Oxide (ITO), silicon or silicon oxide Indium tin oxide (ITSO), indium oxide-zinc oxide (Indium um Zinc Oxide), titanium-containing indium tin oxide, indium Metals such as indium oxide containing titanium oxide, tungsten oxide, and zinc oxide Oxides can be used. In addition, the thickness of the oxide is preferably within a range of 1 nm to 30 nm. A metal thin film having a thickness of 1 μm or less can be used. Examples of metals include Ag, Alloys such as Ag and Al, Ag and Mg, Ag and Au, and Ag and Yb can be used.

[0305] In this specification and the like, a material having a function of transmitting light is a material having a function of transmitting visible light. Any material having the above and having electrical conductivity may be used, and examples thereof include ITO. In addition to oxide conductors, oxide semiconductors and organic conductors containing organic substances are also included. The organic conductor containing the electron donor is, for example, a mixture of an organic compound and an electron donor. Examples of such materials include composite materials made by mixing organic compounds and electron acceptors. Alternatively, an inorganic carbon-based material such as graphene may be used. The rate is preferably 1×10 5 Ω cm or less, more preferably 1×10 4 Ω cm The following is the result.

[0306] In addition, by laminating a plurality of the above materials, one or both of the electrodes 101 and 102 can be formed. may form both.

[0307] In order to improve the light extraction efficiency, the electrode is in contact with the light transmitting electrode. A material having a higher refractive index than the electrode may be used. As long as the material has the function of providing the above, it may be a material that is conductive or not. For example, in addition to the oxide conductors described above, oxide semiconductors and organic materials can be used. The organic material may be, for example, a light-emitting layer, a hole-injecting layer, a hole-transporting layer, an electron-transporting layer, or an electron The materials listed for the electron injection layer are also available. Inorganic carbon-based materials and thin films that transmit light are also available. Using these high refractive index materials, it is possible to form a thin film with a size of several nm to several tens of nm. A plurality of layers may be laminated.

[0308] When the electrode 101 or the electrode 102 functions as a cathode, the work function is small. (3.8 eV or less) materials. For example, Elements in the group (alkali metals such as lithium, sodium, and cesium, calcium, strontium, etc.) Alkaline earth metals such as rontium, magnesium, etc.), alloys containing these elements (e.g., Rare earth metals such as Ag and Mg, Al and Li, europium (Eu), Yb, etc. An alloy containing a metal, such as an alloy containing aluminum or silver, can be used.

[0309] In addition, when the electrode 101 or the electrode 102 is used as an anode, the electrode having a large work function (4. 0 eV or more) materials are preferably used.

[0310] The electrodes 101 and 102 are made of a conductive material having a function of reflecting light and a conductive material having a function of transmitting light. In this case, the electrode 101 and the electrode 102 may be laminated with a conductive material having a permeability function. 02 can resonate light of a desired wavelength from each light-emitting layer and intensify the light of that wavelength. This is preferable because it provides a function for adjusting the optical distance.

[0311] The electrode 101 and the electrode 102 are formed by a method such as sputtering, vapor deposition, printing, or coating. , MBE (Molecular Beam Epitaxy) method, CVD method, pulse laser The deposition method, ALD (Atomic Layer Deposition) method, etc. are used appropriately. It is possible.

[0312] <Substrate> In addition, the light-emitting element according to one embodiment of the present invention is provided on a substrate made of glass, plastic, or the like. Regarding the order of fabrication on the substrate, the layers may be stacked in order from the electrode 101 side. They may be laminated in order from the pole 102 side.

[0313] The substrate on which the light-emitting element according to one embodiment of the present invention can be formed is, for example, glass or quartz. A flexible substrate may be used. The substrate is a flexible substrate, such as polycarbonate. Examples of suitable substrates include plastic substrates made of polyacrylates and polyarylates. Inorganic deposition films and the like can also be used. Any other material may be used as long as it functions as a support in the development. Anything that has the function of protecting the optical elements and the light elements may be used.

[0314] For example, in the present invention, a light emitting element can be formed using various substrates. The type of the substrate is not particularly limited. An example of the substrate is a semiconductor substrate (e.g., a single crystal substrate or silicon substrate), SOI substrate, glass substrate, quartz substrate, plastic substrate, metal Substrate, stainless steel substrate, substrate with stainless steel foil, tungsten substrate, substrate with tungsten foil, flexible substrate, laminated film, fibrous Examples of glass substrates include barium phosphide-based paper or base films. Examples include borosilicate glass, aluminoborosilicate glass, and soda-lime glass. Examples of the functional substrate, laminate film, base film, etc. are as follows. For example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), Representative examples include polyethersulfone (PES) and polytetrafluoroethylene (PTFE). For example, plastics such as acrylic resins are used. Examples include polypropylene, polyester, polyvinyl fluoride, or polyvinyl chloride. Examples include polyamide, polyimide, aramid, epoxy, and inorganic. Examples include machine-deposited films and papers.

[0315] In addition, a flexible substrate may be used as the substrate, and the light emitting element may be formed directly on the flexible substrate. Alternatively, a release layer may be provided between the substrate and the light-emitting element. After a part or all of a chip is completed, it is separated from the board and used to transfer it to another board. In this case, the light-emitting element can be transferred onto a substrate having poor heat resistance or a flexible substrate. The above-mentioned peeling layer has a laminated structure of inorganic films, for example, a tungsten film and a silicon oxide film. or a structure in which a resin film such as polyimide is formed on a substrate.

[0316] 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. In addition to the above mentioned substrates, cellophane substrates, stone substrates, wood substrates, fabric substrates (natural fibers (silk, cotton, Hemp), synthetic fibers (nylon, polyurethane, polyester) or regenerated fibers (acetate (including cellulose, cupra, rayon, recycled polyester, etc.), leather substrate, rubber substrate, etc. By using these substrates, light-emitting elements that are not easily broken and have high heat resistance can be produced. The light emitting element may be a small light emitting element, a light emitting element that is lighter in weight, or a light emitting element that is thinner.

[0317] Also, for example, a field effect transistor (FET) is formed on the above-mentioned substrate, and the FET and The light emitting element 150 may be fabricated on the electrically connected electrodes. In this way, an active matrix display device that controls the driving of the light emitting element 150 can be manufactured.

[0318] Note that one embodiment of the present invention has been described in this embodiment. In the following, one embodiment of the present invention will be described. However, the embodiment of the present invention is not limited to these. That is, various inventive aspects are described in this and other embodiments. Therefore, one embodiment of the present invention is not limited to a specific embodiment. For example, one embodiment of the present invention However, one embodiment of the present invention is not limited thereto. For example, depending on the circumstances, one embodiment of the present invention may be applied to a light-emitting element. Alternatively, for example, in one embodiment of the present invention, a triplet excitation energy may be emitted. and at least one host material. The HOMO level of the guest material is higher than the HOMO level of the host material, and the L The energy difference between the UMO and HOMO levels is the energy difference between the LUMO and HOMO levels of the host material. However, one embodiment of the present invention is not limited to this. In some cases, or depending on the situation, in one aspect of the present invention, for example, the guest material The material may not have the function of converting triplet excitation energy into luminescence. The HOMO level of the dopant material does not have to be higher than the HOMO level of the host material. The energy difference between the LUMO level and the HOMO level of the guest material is The energy difference between the HOMO level and the HOMO level may not be larger than that of the HOMO level. In one embodiment, the host material has a singlet excited energy level and a triplet excited energy level. Although an example in which the difference is greater than 0 eV and less than or equal to 0.2 eV has been shown, one embodiment of the present invention is In some cases or depending on the situation, in one aspect of the present invention, For example, the host material has a difference between the singlet excited energy level and the triplet excited energy level of 0. It may be greater than 2 eV.

[0319] The structure shown in this embodiment mode can be used in appropriate combination with other embodiment modes. Cut.

[0320] (Embodiment 2) In this embodiment mode, a light-emitting element having a different structure from that of the light-emitting element shown in Embodiment 1 is used. The light emitting mechanism of the light emitting device will be described below with reference to FIGS. In FIG. 5(A) and FIG. 6(A), the parts having the same functions as those shown in FIG. 1(A) are denoted by the reference numerals. In addition, parts with similar functions may be designated with the same hatch pattern and the reference numerals may be omitted. The same reference numerals will be used to denote the same parts, and detailed descriptions thereof may be omitted.

[0321] <Configuration example 1 of light-emitting element> FIG. 5A is a schematic cross-sectional view of a light-emitting element 250. FIG.

[0322] The light-emitting element 250 shown in FIG. 5A has a pair of electrodes (electrodes 101 and 102) between which , a plurality of light-emitting units (in FIG. 5A, light-emitting unit 106 and light-emitting unit 1 08). Any one of the plurality of light-emitting units has an EL layer 10 0. That is, the light emitting element 150 shown in FIG. The light-emitting element 152 has one light-emitting unit, and the light-emitting element 250 has multiple light-emitting units. In the light-emitting element 250, the electrode 101 functions as an anode. The following description will be given assuming that the electrode 102 functions as a cathode. However, the opposite is also acceptable.

[0323] In addition, in the light-emitting element 250 shown in FIG. 5A, the light-emitting unit 106 and the light-emitting unit The light-emitting units 106 and 108 are stacked, and a charge generating layer is formed between the light-emitting units 106 and 108. The light-emitting unit 106 and the light-emitting unit 108 have the same configuration. For example, it is preferable to use the EL layer 100 in the light-emitting unit 106. It is nice.

[0324] The light emitting element 250 includes a light emitting layer 120 and a light emitting layer 170. In addition to the light-emitting layer 170, the knit 106 includes a hole injection layer 111, a hole transport layer 112, an electron transport The light-emitting unit 108 also includes an emissive 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 Has 9.

[0325] The charge generating layer 115 is formed by adding an acceptor material, which is an electron acceptor, to a hole transporting material. Even if the structure is such that the electron transport material is a material having a donor property, the structure may be such that the donor property is added to the electron transport material. In addition, both of these configurations may be laminated.

[0326] When the charge generating layer 115 contains a composite material of an organic compound and an acceptor substance, As the composite material, the composite material which can be used for the hole-injection layer 111 shown in Embodiment 1 is used. The organic compounds include aromatic amine compounds, carbazole compounds, aromatic carbon compounds, etc. Various compounds such as hydrogen and polymer compounds (oligomers, dendrimers, polymers, etc.) are used. As an organic compound, a hole mobility of 1×10 -6 cm 2 / Vs However, it is preferable to use a substance 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 transport properties, enabling low-voltage and low-current operation. In addition, the anode side surface of the light-emitting unit is in contact with the charge generating layer 115. In this case, the charge generating 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 generating layer 115 also serves as an electron injection layer or an electron transport layer for the light emitting unit. Therefore, the light-emitting unit does not have an electron injection layer or an electron transport layer. is also good.

[0327] The charge generating layer 115 may be a layer including a composite material of an organic compound and an acceptor substance. For example, the organic EL element may be formed as a laminated structure in which layers made of the organic material are combined. A layer including a composite material of a compound and an acceptor material, and a layer including a compound selected from an electron donor material. The compound may be combined with a compound having a high electron transporting property to form a layer. A layer including a composite material of an organic compound and an acceptor substance and a layer including a transparent conductive film are combined. It may be formed by combining the above.

[0328] The charge generating layer 115 sandwiched between the light emitting unit 106 and the light emitting unit 108 is When a voltage is applied between the electrode 101 and the electrode 102, electrons are injected into one of the light-emitting units, It is sufficient if the hole is injected into the other light-emitting unit. For example, in FIG. 5(A), When a voltage is applied so that the potential of electrode 101 is higher than the potential of electrode 102, The charge generating layer 115 injects electrons into the light-emitting unit 106 and holes into the light-emitting unit 108. Enter.

[0329] From the viewpoint of light extraction efficiency, the charge generating layer 115 is required to be transparent to visible light (specifically, It is preferable that the charge generating layer 115 has a visible light transmittance of 40% or more. In addition, the charge generating layer 115 has a lower electrical conductivity than the pair of electrodes (the electrodes 101 and 102). But it still works.

[0330] When the charge generating layer 115 is formed using the above-mentioned material, the light emitting layer is laminated. In this case, the increase in the driving voltage can be suppressed.

[0331] In addition, in FIG. 5(A), a light-emitting element having two light-emitting units has been described. However, the same can be applied to light-emitting devices in which three or more light-emitting units are stacked. As shown in the light-emitting element 250, a plurality of light-emitting units are disposed between a pair of electrodes. By separating the layers, it is possible to achieve high brightness light emission while keeping the current density low. A light-emitting element having a long life and low power consumption can be realized. .

[0332] At least one of the multiple units has the structure shown in the first embodiment. By applying this composition, a light-emitting element with high luminous efficiency can be provided.

[0333] The light-emitting layer 170 of the light-emitting unit 106 is the same as the light-emitting layer 13 shown in the first embodiment. 0 or light-emitting layer 135. In this way, the light-emitting element 250 has the following structure: This is preferable as it becomes a light emitting element with high light emitting efficiency.

[0334] As shown in FIG. 5B, the light-emitting layer 120 of the light-emitting unit 108 is The light-emitting device includes a guest material 121 and a host material 122. The guest material 121 is a fluorescent material. , as explained below.

[0335] <Light Emitting Mechanism of the Light Emitting Layer 120> The light emitting mechanism of the light emitting layer 120 will be described below.

[0336] Electrons injected from a pair of electrodes (electrodes 101 and 102) or a charge generating layer and The guest material 1 and the hole recombine in the light-emitting layer 120 to generate an exciton. Since the host material 122 is present in a large amount compared to 21, the generation of excitons An excited state of the material 122 is formed.

[0337] An exciton is a pair of carriers (electrons and holes). Therefore, the material in which the excitons are generated is in an excited state.

[0338] When the excited state of the formed host material 122 is a singlet excited state, the host material 12 The singlet excitation energy is transferred from the S1 level of 2 to the S1 level of the guest material 121. As a result, the singlet excited state of the guest material 121 is formed.

[0339] Since the guest material 121 is a fluorescent material, a singlet excited state occurs in the guest material 121. When the guest material 121 is formed, it quickly emits light. For this purpose, it is preferable that the guest material 121 has a high fluorescence quantum yield. In the case of 1, the same applies when the carriers recombine and the excited state generated is a singlet excited state. It is.

[0340] Next, when the triplet excited state of the host material 122 is formed by carrier recombination, In this case, the energy levels of the host material 122 and the guest material 121 are The correlation between the positions is shown in FIG. 5(C). The notations and symbols in FIG. 5(C) are as follows: In addition, the T1 level of the host material 122 is lower than the T1 level of the guest material 121. Since this is preferable, FIG. 5C illustrates this case. may be higher than the T1 level of the guest material 121.

[0341] 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 the host material 122 T FH : T1 level of the host material 122

[0342] As shown in Figure 5(C), triplet-triplet annihilation (TTA) The triplet generated by carrier recombination is Excitons interact with each other, transferring excitation energy and exchanging spin angular momentum. As a result, the S1 level (S FH ) energy A reaction occurs in which the host material 122 is converted into a singlet exciton (see TTA in Figure 5(C)). The singlet excitation energy of is S FH From the lower energy guest material 121 The S1 level of (S FG ) energy transfer occurs (Figure 5(C) Route E 5 See below), Guest A singlet excited state of the material 121 is formed, and the guest material 121 emits light.

[0343] In addition, when the density of triplet excitons in the light-emitting layer 120 is sufficiently high (for example, 1×10 -12 cm -3 In the above, the deactivation of a single triplet exciton is ignored, and the deactivation of two adjacent triplet excitons is considered. We can only consider reactions caused by the initiator.

[0344] In addition, when carriers recombine in the guest material 121 to form a triplet excited state, However, the triplet excited state of the guest material 121 is thermally deactivated, making it difficult to utilize it for light emission. However, the T1 level (T FH ) is the T1 equivalent of guest material 121 Place(T FG ), the triplet excitation energy of guest material 121 is lower than that of guest material 1 21 T1 levels (T FG ) to the T1 level (T FH ) Energy transfer (Fig. 5(C) Route E 6 ) and then used for TTA.

[0345] That is, the host material 122 converts triplet excitation energy into singlet excitation energy by TTA. It is preferable that the light-emitting layer 120 has a function of converting the generated energy into the light-emitting layer 120. A portion of the triplet excitation energy is converted to singlet excitation energy by TTA in the host material 122. The singlet excitation energy is converted into singlet energy, and the singlet excitation energy is transferred to the guest material 121, thereby producing a fluorescent To achieve this, the S1 level (S FH ) is the S1 level (S FG ) is preferable. The T1 level (T FH ) is the T1 level (T FG ) lower It is preferable.

[0346] In particular, the T1 level (T FG ) is the T1 level of the host material 122 ( T FH ), the weight ratio of the host material 122 to the guest material 121 is In particular, it is preferable that the weight ratio of the guest material 121 is low. The weight ratio of the guest material 121 at this time is preferably greater than 0 and less than or equal to 0.05. This can reduce the probability of carrier recombination in the guest material 121. In addition, the T1 level (T FH ) to the T1 level (T FG ) This can reduce the probability of energy transfer to the

[0347] The host material 122 may be composed of a single compound or a plurality of compounds. It may be formed.

[0348] In addition, the light-emitting units 106 and 108 have guest materials that emit light of different colors. In this case, the emission from the light-emitting layer 120 has a peak in the shorter wavelength side than the emission from the light-emitting layer 170. It is preferable to use a material having a high triplet excitation energy level. The light-emitting element used in this study tends to have a tendency to deteriorate in luminance quickly. By using TA, it is possible to provide a light-emitting element with little deterioration in luminance.

[0349] <Light-emitting element configuration example 2> FIG. 6A is a schematic cross-sectional view of the light emitting element 252. FIG.

[0350] The light emitting element 252 shown in FIG. 6A has a pair of electrodes, similar to the light emitting element 250 shown above. A plurality of light-emitting units (light-emitting elements in FIG. 6A) are disposed between the electrodes 101 and 102. At least one of the light-emitting units is The light-emitting unit 106 and the light-emitting unit 110 have the same structure as the EL layer 100. may be of the same or different configurations.

[0351] In addition, in the light-emitting element 252 shown in FIG. 6A, the light-emitting unit 106 and the light-emitting unit The light-emitting unit 106 and the light-emitting unit 110 are laminated, and a charge generating layer is formed between the light-emitting unit 106 and the light-emitting unit 110. For example, the EL layer 100 is preferably used for the light-emitting unit 106. It is nice.

[0352] The light emitting element 252 includes a light emitting layer 140 and a light emitting layer 170. In addition to the light-emitting layer 170, the knit 106 includes a hole injection layer 111, a hole transport layer 112, an electron transport The light-emitting unit 110 also includes an emissive layer 140. 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 Has 9.

[0353] At least one of the multiple units has the structure shown in the first embodiment. By applying this composition, a light-emitting element with high luminous efficiency can be provided.

[0354] In addition, it is preferable that the light-emitting layer of the light-emitting unit 110 contains a phosphorescent material. The light-emitting layer 140 of the unit 110 includes a phosphorescent material, and the light-emitting unit 106 includes The light-emitting layer 170 has the configuration of the light-emitting layer 130 or the light-emitting layer 135 shown in the first embodiment. An example of the configuration of the light emitting element 252 in this case will be described below.

[0355] The light-emitting layer 140 of the light-emitting unit 110 is composed of a guest material 1 as shown in FIG. The host material 142 includes an organic compound 142_ The light-emitting layer 140 includes a guest material 141 and an organic compound 142_2. 1 is a phosphorescent material, which will be described below.

[0356] <Light Emitting Mechanism of the Light Emitting Layer 140> Next, the light emitting mechanism of the light emitting layer 140 will be described below.

[0357] The organic compound 142_1 and the organic compound 142_2 in the light-emitting layer 140 form an exciplex. Form.

[0358] The combination of organic compound 142_1 and organic compound 142_2 forms an exciplex with each other. Any combination that can form a hole transporting compound is acceptable. It is more preferable that the other is a compound having an electron transporting property.

[0359] The organic compound 142_1, the organic compound 142_2, and the guest material in the light-emitting layer 140 The correlation between the energy levels of 141 and 142 is shown in FIG. 6(C). The symbols and symbols 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 guest material 141 (phosphorescent material) ·S PH1 : S1 level of organic compound 142_1 (host material) T PH1 :T1 level of organic compound 142_1 (host material) ·S PH2 : S1 level of organic compound 142_2 (host material) T PH2 :T1 level of organic compound 142_2 (host material) ·S PE : S1 level of the exciplex T PE :T1 level of the exciplex

[0360] The organic compound 142_1 and the organic compound 142_2 form an exciplex, and the S 1 level (S PE ) and T1 level (T PE ) are adjacent energy levels (Figure 6( C) Route E 7 reference).

[0361] Organic compound 142_1 and organic compound 142_2 are such that one 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 the 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 host material 142 to form an excited state with the electrons. The driving voltage of the element can be reduced.

[0362] And the (S PE ) and (T PE ) and the energy of the guest material 141 (Phosphorescent material) to the T1 level to obtain light emission (Figure 6(C) Route E 8 , E 9 three (see).

[0363] 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 in the S1 level (S PE ) and T1 level (T PE )mosquito The T1 level (T PG ) energy can be transferred to

[0364] In order to efficiently transfer excitation energy from the exciplex to the guest material 141, , the T1 level of the exciplex (T PE ) are each organic compound that forms an exciplex (organic compound 14 2_1 and organic compound 142_2) T1 level (T PH1 and T PH2 ) or As a result, each of the organic compounds (organic compound 142_1 and organic Compound 142_2) is less likely to quench the triplet excitation energy of the exciplex. As a result, energy transfer occurs efficiently from the exciplex to the guest material 141.

[0365] In addition, the organic compound 142_1 and the organic compound 142_2 efficiently form an exciplex. In order to achieve this, the HOMO level of one of the organic compounds 142_1 and 142_2 must be The HOMO level of one is higher than the LUMO level of the other, and the LUMO level of the other is higher than the LUMO level of the other. For example, the organic compound 142_1 has a hole transporting property, and the organic compound 142_2 has a hole transporting property. When the organic compound 142_1 has electron transport properties, the HOMO level of the organic compound 142_2 It is preferable that the LUMO level of the organic compound 142_1 is higher than the HOMO level of the organic compound 142_2. It is preferable that the LUMO level of the organic compound 142_2 is higher than that of the organic compound 142_3. When organic compound 142 has a hole transporting property and organic compound 142_1 has an electron transporting property, organic compound 1 It is preferable that the HOMO level of 42_2 is higher than the HOMO level of the organic compound 142_1. , the LUMO level of organic compound 142_2 is higher than the LUMO level of organic compound 142_1. Specifically, it is preferable that the HOMO level of the organic compound 142_1 and the HOMO level of the organic compound 142 The energy difference between the HOMO level of _2 is preferably 0.05 eV or more, and more preferably The electron transport potential is preferably 0.1 eV or more, and more preferably 0.2 eV or more. 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 even more preferably It is preferably 0.2 eV or more.

[0366] In addition, the combination of organic compound 142_1 and organic compound 142_2 has hole transport properties. In the case of a combination of a compound having a property of electron transport and a compound having a property of electron transport, the mixing ratio Specifically, the carrier balance can be easily controlled by using a hole transporting material. The weight ratio of the compound having an electron transporting property to the compound having an electron transporting property is preferably in the range of 1:9 to 9:1. In addition, by having this configuration, the carrier balance can be easily controlled. In addition, the carrier recombination region can be easily controlled.

[0367] In addition, the energy transfer between the host material 142 (exciplex) and the guest material 141 is The mechanism of the dynamic process is the Förster mechanism (dipole-dipole interaction) as in the first embodiment. This can be explained by two mechanisms: the electron exchange mechanism and the Dexter mechanism. For the Förster mechanism and the Dexter mechanism, please refer to the first embodiment. .

[0368] Therefore, the host material (exciplex) can be excited in a singlet state to a triplet state in the guest material 141. In order to facilitate the energy transfer to the excited state, the emission spectrum of the exciplex and the It is preferable that the absorption band of the photoresist material 141 overlaps with the absorption band of the photoresist material 142 that appears on the longest wavelength side (lowest energy side). By doing so, it is possible to increase the efficiency of generating the triplet excited state of the guest material 141. do.

[0369] By configuring the light-emitting layer 140 as described above, the guest material 141 (phosphorescent material ) can be efficiently obtained.

[0370] In addition, Route E shown above 7 ~E 9 The process is referred to as ExTET (Ex It is sometimes called plex-triplet energy transfer. In other words, the light-emitting layer 140 is configured to transmit the excitation energy from the exciplex to the guest material 141. In this case, the T PE From S PE High efficiency of reverse intersystem crossing is required Instead, S PE Since the quantum yield of light emitted from the It becomes possible.

[0371] In addition, the emission from the light-emitting layer 170 has an emission peak on the shorter wavelength side than the emission from the light-emitting layer 140. It is preferable that the light-emitting element has a phosphorescent material that emits light of a short wavelength. Therefore, by using fluorescent light for short wavelengths, It is possible to provide a light emitting element with little deterioration in luminance.

[0372] In each of the above configurations, the light-emitting unit 106 and the light-emitting unit 108, or the light-emitting The emission colors of the guest materials used in the unit 106 and the light-emitting unit 110 include: The light-emitting units 106 and 108 may be the same or different. Alternatively, the light emitting unit 106 and the light emitting unit 110 may have a function of emitting light of the same color. When the light-emitting element 250 and the light-emitting element 252 have a guest material having a light-emitting function, the light-emitting element 250 and the light-emitting element 252 can emit a small amount of current. In addition, the light-emitting unit 106 and the light-emitting unit 107 are preferably light-emitting elements that exhibit high light-emitting luminance. The light emitting units 108, 106, and 110 may be of different colors. In the case where a guest material having a function of emitting light is included, the light-emitting element 250 and the light-emitting element 252 In this case, the light-emitting layer 120 and the light-emitting layer 170 are preferably light-emitting elements that emit multicolor light. or either or both of light-emitting layer 140 and light-emitting layer 170 By using a plurality of light-emitting materials with different emission wavelengths for both the light-emitting element 250 and the The emission spectrum of the light emitting element 252 is a composite of emission having different emission peaks. The resulting light has an emission spectrum with at least two maxima.

[0373] The above-mentioned configuration is also suitable for obtaining white light emission. Alternatively, the light from the light-emitting layer 140 and the light-emitting layer 170 may be made to have a complementary color relationship, thereby producing a white light. In particular, white light with high color rendering, or at least red and green light, can be obtained. It is preferable to select the guest material so as to have a blue emission.

[0374] At least one of the light-emitting layer 120, the light-emitting layer 140, and the light-emitting layer 170 is formed in a layered form. The light-emitting element may be divided into layers, and each divided layer may contain a different light-emitting material. At least one of the light-emitting layers 120, 140, and 170 is a multi-layer structure having two or more layers. For example, the first light-emitting layer and the second light-emitting layer may be arranged on the hole transport layer side. When the first light-emitting layer is formed by laminating the first and second light-emitting layers in this order, a hole-transporting material is used as the host material of the first light-emitting layer. and a material having an electron transporting property is used as a host material for the first light-emitting layer. In this case, the light-emitting material contained in the first light-emitting layer and the second light-emitting layer is the same material. The materials may be different from each other, and may be materials that have the function of emitting light of the same color. The materials may have a function of emitting light of different colors. By using a structure that has multiple light-emitting materials with the function of emitting light in three primary colors or four or more colors, It is also possible to obtain white light emission with high color rendering properties.

[0375] <Examples of materials that can be used for the light-emitting layer> Next, materials that can be used for the light-emitting layers 120, 140, and 170 will be described. The following describes each of these.

[0376] <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 is The fluorescent material is dispersed in the host material 122. The S1 level of the host material 122 is The S1 level of the host material 121 (fluorescent material) is higher than the T1 level of the host material 122. It is preferable that the T1 level is lower than the T1 level of the photoresist material 121 (fluorescent material).

[0377] In the light-emitting layer 120, the guest material 121 is not particularly limited, but may be anthracene. Derivatives, tetracene derivatives, chrysene derivatives, phenanthrene derivatives, pyrene derivatives, Rylene derivatives, stilbene derivatives, acridone derivatives, coumarin derivatives, phenoxazine Derivatives, phenothiazine derivatives, etc. are preferred, and for example, the following materials can be used: .

[0378] 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 1,6-Pyrene-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn) , N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H -fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMem FLPAPrn), N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl )phenyl]-N,N'-bis(4-tert-butylphenyl)pyrene-1,6-diazo 1,6tBu-FLPAPrn, N,N'-diphenyl-N,N'-bis(1,6tBu-FLPAPrn) [4-(9-phenyl-9H-fluoren-9-yl)phenyl]-3,8-dicyclohexyl Xylpyrene-1,6-diamine (abbreviation: ch-1,6FLPAPrn), N,N'-biphenyl S[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenylstilbe YGA2S, 4-(9H-carbazol-9-yl) -4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA) , 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl-2-anthracene N,9-diphenyl-N-[4- (10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation 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-diyldi-4,1-phenylene) Bis[N,N',N'-triphenyl-1,4-phenylenediamine] (abbreviation: DPAB PA), N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl] phenyl]-9H-carbazol-3-amine (abbreviation: 2PCAPPA), N-[4-(9 ,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1 ,4-Phenylenediamine (abbreviation: 2DPAPPA), N,N,N',N',N'',N '',N''',N'''-Octaphenyldibenzo[g,p]chrysene-2,7,10 ,15-Tetraamine (abbreviation: DBC1), Coumarin 30, N-(9,10-diphenyl -2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2 PCAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthracene aryl]-N,9-diphenyl-9H-carbazol-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'-biphenyl) phenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N- Phenylanthracene-2-amine (abbreviation: 2YGABPhA), N,N,9-triphenyl Dianthracene-9-amine (abbreviation: DPhAPhA), Coumarin 6, Coumarin 545T , N,N'-diphenylquinacridone (abbreviation: DPQd), rubrene, 2,8-di-te rt-Butyl-5,11-bis(4-tert-butylphenyl)-6,12-diphenyl Tetrathracene (abbreviation: TBRb), Nile Red, 5,12-bis(1,1'-biphenyl) 2-(2-(2-phenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT), [4-(Dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyran-4-yl 2-(2-methyl-6-[2-(2,3-dimethylphenyl)propanedinitrile (abbreviation: DCM1), ,6,7-Tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl ]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM2), N,N,N ',N'-Tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N',N'-tetrakis(4-methyl phenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviation: p -mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl 2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl )Ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTI) , 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3, 6,7-Tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl] -4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB), 2-(2, 6-Bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4-yl 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}p Dopanedinitrile (abbreviation: BisDCJTM), 5,10,15,20-tetraphenyl Bisbenzo[5,6]indeno[1,2,3-cd:1',2',3'-lm]perylene , etc.

[0379] In addition, materials that can be used as the host material 122 in the light-emitting layer 120 include: Although there is no particular limitation, for example, tris(8-quinolinolato)aluminum(III) (abbreviation : Alq), tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviation: Almq 3 ), bis(10-hydroxybenzo[h]quinolinato)beryllium(II)( Abbreviation: BeBq 2 ), 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, such as 2-(4-biphenylyl)-5-(4-tert- butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5 -(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene Zene (abbreviation: OXD-7), 3-(4-biphenylyl)-4-phenyl-5-(4-tetraphenyl) 2,2',2' rt-Butylphenyl)-1,2,4-triazole (abbreviation: TAZ) '-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazo TPBI, bathophenanthroline (BPhen), bathocuproline BCP, 9-[4-(5-phenyl-1,3,4-oxadiazole-2- Heterocyclic compounds such as 4,4-phenyl-9H-carbazole (abbreviation: CO11), '-Bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB or is α-NPD), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1 ,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4'-bis[N-( Spiro-9,9'-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation Aromatic amine compounds such as bis(phenylene phosphate phosphate) and bis(phenylene phosphate phosphate). Nanthrene derivatives, pyrene derivatives, chrysene derivatives, dibenzo[g,p]chrysene derivatives Condensed polycyclic aromatic compounds such as 9,10-diphenylanthracene are specifically exemplified. (abbreviation: DPAnth), N,N-diphenyl-9-[4-(10-phenyl-9-anth tolyl)phenyl]-9H-carbazol-3-amine (abbreviation: CzA1PA), 4-( 10-phenyl-9-anthryl)triphenylamine (abbreviation: DPhPA), 4-(9 H-Carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenyl YGAPA, N,9-diphenyl-N-[4-(10-phenyl-9 -anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), ,9-diphenyl-N-{4-[4-(10-phenyl-9-anthryl)phenyl]furan N,9-diphenyl}-9H-carbazol-3-amine (abbreviation: PCAPBA), N-(9,10-diphenyl-2-anthryl)-9H-carbazol-3-amine (abbreviation: 2PCAPA), 6,12-dimethoxy-5,11-diphenylchrysene, N, N,N',N',N'',N'',N''',N'''-Octaphenyldibenzo[g, p]chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), 9-[4-(1 0-Phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: CzPA), 3,6-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H -Carbazole (abbreviation: DPCzPA), 9,10-bis(3,5-diphenylphenyl )anthracene (abbreviation: DPPA), 9,10-di(2-naphthyl)anthracene (abbreviation: :DNA), 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation :t-BuDNA), 9,9'-Bianthryl (abbreviation: BANT), 9,9'-(styryl Ben-3,3'-diyl)diphenanthrene (abbreviation: DPNS), 9,9'-(stilbe 1,3,5-triphenyl-4,4'-diyl)diphenanthrene (abbreviation: DPNS2), -pyrenyl)benzene (abbreviation: TPB3). Among known substances, a substance having an energy gap larger than that of the guest material 121 is selected. One or more types of material having gaps may be selected and used.

[0380] The light-emitting layer 120 may be composed of two or more layers. When the light-emitting layer 120 is formed by laminating the first light-emitting layer and the second light-emitting layer in this order from the hole transport layer side, A substance having a hole transporting property is used as a host material for the first light-emitting layer, and a substance having a hole transporting property is used as a host material for the second light-emitting layer. For example, a substance having an electron transport property is used as the insulating film.

[0381] In the light-emitting layer 120, the host material 122 is composed of a single compound. Alternatively, the light-emitting layer 120 may be made of a single compound or a plurality of compounds. The layer may contain materials other than the host material 122 and the guest material 121 .

[0382] <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 The phosphorescent material is dispersed in the host material 142. The T1 level of the organic compound 142_1 and the organic compound 142_2 is the T A level higher than 1 is preferred.

[0383] Organic compounds 142_1 include zinc and aluminum metal complexes, as well as oxadiazo derivatives, triazole derivatives, benzimidazole derivatives, quinoxaline derivatives, dibenzyl derivatives, Dibenzothiophene derivatives, dibenzofuran derivatives, pyrimidine derivatives, triazine derivatives, pyridine derivatives, bipyridine derivatives, phenanthroline derivatives Other examples include aromatic amines and carbazole derivatives. Specifically, the electron transporting material and the hole transporting material shown in Embodiment 1 are used. It is possible.

[0384] The organic compound 142_2 is a compound capable of forming an exciplex with the organic compound 142_1. Specifically, the electron transport material and the hole transport material shown in the first embodiment 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 exciplex formed is the triplet MLCT ( Metal to Ligand Charge Transfer (MTC) 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 object 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 singlet absorption band. It is preferable that the ferroelectric material is a conductive material.

[0385] The guest material 141 (phosphorescent material) is an iridium, rhodium, or platinum-based organic Metal complexes, particularly organic iridium complexes, such as iridium The ortho-metal complex is preferably a 4H-triazole. Ligand, 1H-triazole ligand, imidazole ligand, pyridine ligand, pyrimidine Ligands include pyrazine ligands, isoquinoline ligands, and the like. Examples of the platinum complex include a platinum complex having a porphyrin ligand. The materials exemplified as the guest material 131 in 1 can be used.

[0386] The light-emitting material contained in the light-emitting layer 140 is a material capable of converting triplet excitation energy into light emission. As a material capable of converting the triplet excitation energy into light emission, a phosphorescent material is In addition to the above, thermally activated delayed fluorescent materials are also included. In other words, it may be interpreted as a thermally activated delayed fluorescent material.

[0387] In addition, materials that exhibit thermally activated delayed fluorescence can be independently converted from a triplet excited state to a single excited state by reverse intersystem crossing. The material may be capable of generating a doublet excited state, or may be an exciplex (or The material may be made of multiple materials that form a single layer (also called an exciplex).

[0388] When the thermally activated delayed fluorescent material is composed of one kind of material, specifically, The thermally activated delayed fluorescent material shown in 1 can be used.

[0389] In addition, when a thermally activated delayed fluorescent material is used as a host material, two types of exciplexes are formed. It is preferable to use a combination of the above-mentioned compounds. The combination of compounds that accept electrons and compounds that accept holes is called It is particularly preferred to use

[0390] <Materials that can be used for the light-emitting layer 170> The material that can be used for the light-emitting layer 170 is the same as that used for the light-emitting layer in the first embodiment. By using materials that can be used in the light-emitting device, a light-emitting device with high light-emitting efficiency can be created. It can be manufactured.

[0391] In addition, the emission colors of the light-emitting materials contained in the light-emitting layers 120, 140, and 170 are There is no limitation, and each may be the same or different. The light emitted from each is mixed. For example, if the two emission colors are complementary to each other, The light-emitting layer 120 can emit white light. The emission peak wavelength of the luminescent material contained in the luminescent layer 170 is shorter than that of the luminescent material contained in the luminescent layer 170. is preferred.

[0392] The light-emitting unit 106, the light-emitting unit 108, the light-emitting unit 110, and the charge generating The layer 115 can be formed by deposition (including vacuum deposition), inkjet printing, coating, gravure printing, etc. The method can be formed as follows.

[0393] The configuration described in this embodiment mode may be used in appropriate combination with the configurations described in other embodiments. There can be.

[0394] (Embodiment 3) In this embodiment mode, a light-emitting element having a different structure from those shown in Embodiments 1 and 2 is described. An example of this will be described below with reference to FIGS.

[0395] <Configuration example 1 of light-emitting element> 7(A) and (B) are cross-sectional views showing a light-emitting element according to one embodiment of the present invention. In FIG. 1B, the same hatching is used for the parts having the same functions as those shown in FIG. 1A. In addition, parts with similar functions are labeled with similar symbols. In some cases, reference symbols will be used and detailed descriptions thereof will be omitted.

[0396] The light emitting element 260a and the light emitting element 260b shown in FIG. The light emitting element may be a bottom emission type light emitting element that extracts light from the substrate 200. It may be a top emission type light emitting element that extracts light in the opposite direction. Note that one embodiment of the present invention is not limited thereto. It may be a dual emission type light emitting element in which light is emitted from both the upper and lower sides. .

[0397] When the light emitting element 260a and the light emitting element 260b are bottom emission type, the electrode 1 The electrode 101 preferably has a function of transmitting light. In addition, the electrode 102 preferably has a function of reflecting light. Alternatively, the light emitting element 260a and the light emitting element 260b may have a function of In the case of a top emission type, the electrode 101 preferably has a function of reflecting light. In addition, the electrode 102 preferably has a function of transmitting light.

[0398] The light emitting element 260a and the light emitting element 260b are formed by providing an electrode 101 and an electrode 102 on a substrate 200. In addition, between the electrode 101 and the electrode 102, a light-emitting layer 123B and a light-emitting layer 123 G and a light-emitting layer 123R. Also, the light-emitting layer 123 has a hole injection layer 111, a hole transport layer 112, It has an electron transport layer 118 and an electron injection layer 119 .

[0399] In addition, the light-emitting element 260b includes, as a part of the configuration of the electrode 101, a conductive layer 101a and a conductive The conductive layer 101b is located above the conductive layer 101a, and the conductive layer 101c is located below the conductive layer 101a. That is, in the light emitting element 260b, the conductive layer 101a is made up of the conductive layer 101b and the conductive layer 101c. It has a sandwiched electrode 101 configuration.

[0400] In the light emitting element 260b, the conductive layer 101b and the conductive layer 101c are made of different materials. The electrodes 101 may be made of the same material, and the conductive layer 101a may be made of the same conductive material. In the case where the electrode 101 is sandwiched between conductive materials, the etching step in the process of forming the electrode 101 This is preferable because it facilitates pattern formation by the method.

[0401] In the light-emitting element 260b, the conductive layer 101b or the conductive layer 101c A configuration having only one of them may be used.

[0402] The conductive layers 101a, 101b, and 101c of the electrode 101 are The same configuration and material as the electrode 101 or the electrode 102 shown in the first embodiment can be used. Cut.

[0403] In FIG. 7(A) and (B), a region 221B sandwiched between the electrodes 101 and 102, A partition wall 145 is provided between the region 221G and the region 221R. The partition wall 145 has an insulating property. The partition 145 covers an end of the electrode 101 and has an opening overlapping the electrode. By providing the walls 145, the electrodes 101 on the substrate 200 in each region are arranged in an island shape. It becomes possible to separate.

[0404] In addition, in the region where the light-emitting layer 123B and the light-emitting layer 123G overlap with the partition wall 145, Alternatively, the light-emitting layer 123G and the light-emitting layer 123R may have an overlapping region. In the region where they overlap with the partition wall 145, they may have an overlapping region with each other. In the region where the light-emitting layer 123R and the light-emitting layer 123B overlap with the partition wall 145, It may have an overlapping area.

[0405] The partition wall 145 may be formed using an inorganic or organic material as long as it has insulating properties. The inorganic material may be silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, etc. Examples of the organic material include silicon, aluminum oxide, and aluminum nitride. For example, photosensitive resin materials such as acrylic resin and polyimide resin can be used.

[0406] The silicon oxynitride film is a film whose composition contains more oxygen than nitrogen. Preferably, oxygen is 55 atomic % or more and 65 atomic % or less, and 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 is a film that contains more nitrogen than oxygen as its composition. It refers to a film with a high content of nitrogen, preferably 55 atomic % to 65 atomic % and 1 % to 20 atomic %, silicon is 25 atomic % to 35 atomic %, hydrogen is 0.1 atomic % This refers to a film containing this element in a concentration range of 10 atomic % or more.

[0407] In addition, the light-emitting layers 123R, 123G, and 123B each exhibit a different color. For example, the light-emitting layer 123R may have a red light-emitting material. By including a light-emitting material having a function of emitting red light, the region 221R emits red light, and the light-emitting layer 12 Since the region 3G has a light-emitting material having a function of emitting green light, the region 221G emits green light. The light-emitting layer 123B has a light-emitting material having a function of emitting blue light, so that the region 221 The light emitting element 260a or the light emitting element 26B emits blue light. By using 0b in the pixels of a display device, a display device capable of full color display can be manufactured. The thickness of each light-emitting layer may be the same or different. good.

[0408] In addition, any one or more of the light-emitting layers 123B, 123G, and 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.

[0409] In addition, any one or more of the light-emitting layers 123B, 123G, and 123R The light emitting layer may have a structure in which two or more layers are laminated.

[0410] 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 for a display device. By using the organic EL element in the pixels of a display device, a display device with high light emission 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.

[0411] In addition, if an optical element (e.g., 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 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 reduce the reflection of external light. The contrast ratio of a display device having the element 260b can be increased.

[0412] 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.

[0413] <Light-emitting element configuration example 2> Next, regarding a configuration example of the light-emitting element different from that shown in FIG. 7(A)(B), FIG. 8(A)(B) will be described. The following description will be given using this.

[0414] 8(A) and (B) are cross-sectional views showing a light-emitting element according to one embodiment of the present invention. 7(A) and (B), the same reference numerals are used for the parts having the same functions as those shown in FIG. In some cases, the symbols are omitted and hatched patterns are used. Also, parts with similar functions are indicated by Similar reference symbols are used and detailed descriptions thereof may be omitted.

[0415] 8(A) and (B) show examples of the configuration of a light-emitting element having a light-emitting layer between a pair of electrodes. The light emitting element 262a shown in (A) is a top-emitting (top-emitting) element that extracts light in the direction opposite to the substrate 200. The light emitting element 262b shown in FIG. 8B is a top emission type light emitting element. However, the present invention is directed to a bottom emission type light emitting device. One embodiment is not limited to this, and light emitted by the light emitting element may be emitted on the substrate 200 on which the light emitting element is formed. It may also be of a dual emission type in which light is emitted from both the top and bottom.

[0416] The light emitting element 262a and the light emitting element 262b are formed by providing an electrode 101 and an electrode 102 on a substrate 200. , an electrode 103, and an electrode 104. In addition, between the electrode 101 and the electrode 102, and At least a light emitting layer is formed between the electrode 102 and the electrode 103 and between the electrode 102 and the electrode 104. The organic electroluminescent device includes a layer 170, a light-emitting layer 190, and a charge-generating layer 115. The organic electroluminescent device also includes a hole-injecting layer 111 and a charge-generating layer 120. , a hole transport layer 112, an electron transport layer 113, an electron injection layer 114, and a hole injection layer 116. , a hole transport layer 117 , an electron transport layer 118 , and an electron injection layer 119 .

[0417] 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 that is 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 a conductive layer 104b.

[0418] The light emitting element 262a shown in FIG. 8(A) and the light emitting element 262b shown in FIG. 8(B) have an electrode The region 222B sandwiched between the electrodes 101 and 102, and the region 222B sandwiched between the electrodes 102 and 103 and a region 222R sandwiched between the electrode 102 and the electrode 104. The partition wall 145 has an insulating property. The partition wall 145 is provided between the electrode 101 and the electrode 1 The separator 145 covers the end of the electrode 103 and the end of the electrode 104 and has an opening overlapping the electrode. By this, the electrodes on the substrate 200 in each region can be separated into islands. It becomes Noh.

[0419] The charge generating layer 115 is formed by adding an electron acceptor to a hole transporting material. or an electron transport material to which an electron donor (donor) has been added, In addition, when the electrical conductivity of the charge generating layer 115 is as high as that of the pair of electrodes, In this case, carriers generated by the charge generating layer 115 flow to adjacent pixels, Therefore, it is necessary to prevent adjacent pixels from emitting light incorrectly. In order to achieve this, the charge generating layer 115 is formed of a material having a lower electrical conductivity than the pair of electrodes. preferable.

[0420] The light emitting element 262a and the light emitting element 262b are disposed in the regions 222B, 222G, and In the direction in which the light emitted from the region 222R is extracted, the optical element 224B and the optical element The substrate 220 has the optical element 224G and the optical element 224R. The light emitted from the region 222B is emitted to the outside of the light emitting element through each optical element. The light coming from the region 222G is emitted through the optical element 224B. The light emitted from the region 222R through the optical element 224G is It is ejected.

[0421] In addition, the optical elements 224B, 224G, and 224R are For example, the optical element 224B has a function of selectively transmitting light of a specific color. The light emitted from the region 222B through the optical element 22 is blue light. The light emitted from the area 222G via the optical element 4G is green light. The light emitted from the region 222R via the element 224R is red light.

[0422] The optical element 224R, the optical element 224G, and the optical element 224B may include, for example, a colored layer ( Color filters, bandpass filters, multilayer filters, etc. can be used. In addition, a color conversion element can be applied to the optical element. The color conversion element converts incident light into the corresponding color. The color conversion element is an optical element that converts the wavelength of the light into light with a longer wavelength than the wavelength of the light. By using quantum dots, the color reproducibility of the display device can be improved. can be increased.

[0423] In addition, if other optical elements are arranged on the optical elements 224R, 224G, and 224B, The other optical elements may be, for example, a circular polarizing plate or an anti-reflection plate. The circular polarizing plate is placed in a position where the light emitted by the light emitting element of the display device is taken out. When the light source is provided on the side where the light source is turned on, the light incident from the outside of the display device is reflected inside the display device and In addition, the provision of an anti-reflection film can prevent the light from being projected onto the surface of the display device. This reduces the amount of external light reflected by the display device, making the light emitted by the display device clearer. It can be observed.

[0424] In FIG. 8(A) and (B), the light emitted from each region through each optical element is Light exhibiting color (B), light exhibiting green (G), and light exhibiting red (R), respectively. This is illustrated diagrammatically by dashed arrows.

[0425] In addition, a light-shielding layer 223 is provided between each optical element. The light-shielding layer 223 is formed to prevent light from entering from adjacent regions. It is to be noted that the light shielding layer 223 may not be provided. stomach.

[0426] The light-shielding layer 223 has a function of suppressing reflection of external light. The light shielding layer 223 has a function of preventing the color mixture of light emitted from adjacent light emitting elements. Examples include metals, resins containing black pigments, carbon black, metal oxides, and multiple metal oxides. A composite oxide containing a solid solution of such a material can be used.

[0427] In addition, the optical element 224B and the optical element 224G are arranged in a region where they overlap with the light-shielding layer 223. Alternatively, the optical element 224G and the optical element 224R is a region overlapping with the light-shielding layer 223, even if they have mutually overlapping regions. Alternatively, the optical element 224R and the optical element 224B may overlap with the light-shielding layer 223. The regions may have overlapping regions.

[0428] The substrate 200 and the substrate 220 having the optical element are configured as in the first embodiment. Please take this into consideration.

[0429] Furthermore, the light emitting element 262a and the light emitting element 262b have a microcavity structure. .

[0430] <Microcavity structure> The light emitted from the light emitting layer 170 and the light emitting layer 190 is incident on a pair of electrodes (for example, the electrode 10 The light emitting layer 170 and the light emitting layer 190 are resonated between the electrode 102 and the light emitting layer 170. For example, the reflection area of ​​the electrode 101 is formed at a position where the light of the desired wavelength is intensified. The optical distance from the reflecting area of ​​the electrode 102 to the light emitting area of ​​the light emitting layer 170 is By adjusting the optical distance to the light emitting region, the amount of light emitted from the light emitting layer 170 can be reduced. In addition, the light emitted from the reflective area of ​​the electrode 101 to the light emitting layer 190 can be intensified. and the optical distance from the reflective area of ​​the electrode 102 to the luminous area of ​​the luminous layer 190. By adjusting the optical distance, the light emitted from the light emitting layer 190 can be adjusted to a desired wavelength. That is, the light can be intensified by using a plurality of light-emitting layers (here, the light-emitting layer 170 and the light-emitting layer In the case of a light emitting device in which the light emitting layer 170 and the light emitting layer 190 are laminated, the optical distances of the light emitting layer 170 and the light emitting layer 190 are It is preferable to optimize the spacing.

[0431] In the light emitting element 262a and the light emitting element 262b, the conductive layer (conductive layer 1) is formed in each region. By adjusting the thicknesses of the conductive layers 101b, 103b, and 104b, the light-emitting layer 170 In addition, the light emitted from the light emitting layer 190 can be enhanced at a desired wavelength. In the region, at least one of the hole injection layer 111 and the hole transport layer 112, or the electron injection At least one of the layer 119 and the electron transport layer 118 has a different thickness. The light emitted from layer 170 and light-emitting layer 190 may be enhanced.

[0432] For example, the electrodes 101 to 104 are made of a conductive material having a function of reflecting light. In the case where the refractive index is smaller than that of the light-emitting layer 170 or the light-emitting layer 190, the electrode The thickness of the conductive layer 101b of the electrode 101 is set to a value that satisfies the optical distance between the electrode 101 and the electrode 102. B λ B / 2(m B is a natural number, λ B represent the wavelengths of light to be intensified in region 222B, respectively) and Similarly, the thickness of the conductive layer 103b of the electrode 103 is adjusted to be equal to or smaller than the thickness of the conductive layer 103b of the electrode 103. The optical distance between the electrode 102 is m G λ G / 2(m G is a natural number, λ G is strong in the area 222G The wavelength of the light emitted from the electrode 104 is adjusted to be 100 nm. The thickness of the electrode 104b is set to m R λ R / 2(m R is natural number, λ R and represent the wavelengths of light to be intensified in region 222R).

[0433] In addition, when it is difficult to precisely determine the reflection areas of the electrodes 101 to 104, By assuming that any region of the light-emitting layer 170 or the light-emitting electrode 104 is a reflective region, An optical path that enhances the light emitted from the light emitting layer 190 may be derived. In the case where it is difficult to precisely determine the light-emitting region of the light-emitting layer 170 and the light-emitting layer 190, By assuming that any region of the light emitting layer 190 is a light emitting region, the light emitting layer 170 and the light emitting layer 190 An optical path that enhances the light emitted from the

[0434] As described above, a microcavity structure is provided, and the optical distance between a pair of electrodes in each region is adjusted. By arranging the electrodes, light scattering and absorption near each electrode are suppressed, resulting in high light extraction efficiency. The rate can be realized.

[0435] In the above configuration, the conductive layer 101b, the conductive layer 103b, and the conductive layer 104b are optically In addition, the conductive layer 101b, the conductive layer 103b, and the conductive The materials constituting the layers 104a, 104b may be the same or different. When the same material is used for the conductive layer 101b, the conductive layer 103b, and the conductive layer 104b, the electrode 10 1. The pattern formation by the etching process in the process of forming the electrodes 103 and 104 is easy. In addition, the conductive layers 101b, 103b, and 104b are preferably Each of these may have a structure in which two or more layers are laminated.

[0436] In addition, the light emitting element 262a shown in FIG. 8A is a top emission type light emitting element, so that The layer 101a, the conductive layer 103a, and the conductive layer 104a may have a function of reflecting light. In addition, the electrode 102 has a function of transmitting light and a function of reflecting light. is preferred.

[0437] In addition, the light emitting element 262b shown in FIG. 8B is a bottom emission type light emitting element. The layer 101a, the conductive layer 103a, and the conductive layer 104a have a function of transmitting light and a function of reflecting light. In addition, the electrode 102 preferably has a function of reflecting light. preferable.

[0438] In the light-emitting element 262a and the light-emitting element 262b, the conductive layer 101a and the conductive layer 10 3a and conductive layer 104a may be made of the same material or different materials. When the conductive layer 101a, the conductive layer 103a, and the conductive layer 104a are made of the same material, The manufacturing cost of the conductive layer 101a and the light emitting element 262b can be reduced. Each of the conductive layer 103a and the conductive layer 104a may be configured by stacking two or more layers. stomach.

[0439] In addition, the light-emitting layer 170 and the light-emitting layer 190 in the light-emitting element 262a and the light-emitting element 262b At least one of the configurations shown in the first and second embodiments is included in at least one of the first and second embodiments. By doing so, it is possible to manufacture a light-emitting element that exhibits high luminous efficiency. can be done.

[0440] The light-emitting layer 170 and the light-emitting layer 190 are, for example, the light-emitting layer 190a and the light-emitting layer 190b. In this way, one or both of the light-emitting layers may have a structure in which two layers are laminated. The first compound and the second compound are two types of luminescent materials that have the function of exhibiting different colors. By using each of them, multiple lights can be obtained simultaneously. 190 and a luminescent material to be used for each luminescent layer is selected so that the luminescence exhibited by the luminescent layer becomes white. This is preferable.

[0441] In addition, the light-emitting layer 170 or the light-emitting layer 190 may have a structure in which three or more layers are laminated on one or both sides. The light-emitting layer may be made of any material, and may include a layer that does not have a light-emitting material.

[0442] As described above, the present invention can be realized by using at least one of the structures of the light-emitting layer shown in the first and second embodiments. By using the light-emitting element 262a or the light-emitting element 262b having the above structure as a pixel of a display device, A display device with high light efficiency can be manufactured. A display device including the element 262b can consume less power.

[0443] Regarding other configurations of the light emitting element 262a and the light emitting element 262b, 260a or 260b, or the light-emitting element shown in the first and second embodiments. The configuration of the optical element should be taken into consideration.

[0444] <Method of manufacturing light-emitting element> Next, a manufacturing method of a light-emitting element according to one embodiment of the present invention will be described below with reference to FIGS. Here, a method for manufacturing the light-emitting element 262a shown in FIG. do.

[0445] 9 and 10 are cross-sectional views illustrating a method for manufacturing a light-emitting element of one embodiment of the present invention. do.

[0446] The method for fabricating the light emitting element 262a described below includes seven steps, namely, steps 1 to 7. do.

[0447] <First step> The first step is to form an electrode of the light-emitting element (specifically, the conductive layer 101 constituting the electrode 101). a, conductive layer 103a constituting electrode 103, and conductive layer 104a constituting electrode 104) is a step of forming a film on a substrate 200 (see FIG. 9(A)).

[0448] In this embodiment, a conductive layer having a function of reflecting light is formed on a substrate 200. The conductive layer is processed into a desired shape to form the conductive layer 101a, the conductive layer 103a, and the conductive The conductive layer 104a is formed by using a material such as silver and palladium. The conductive film is made of an alloy of Ag and copper (also called Ag-Pd-Cu film or APC). The conductive layer 101a, the conductive layer 103a, and the conductive layer 104a are formed by a process of processing the same conductive layer. This is preferable because it is possible to reduce the manufacturing cost.

[0449] It should be noted that a number of transistors may be formed on the substrate 200 before the first step. In addition, the plurality of transistors, the conductive layer 101a, the conductive layer 103a, and the conductive layer 104a may be electrically connected to each other.

[0450] <<Second step>> In the second step, a light-transmitting layer 101b having a function of transmitting light is formed on the conductive layer 101a constituting the electrode 101. The conductive layer 101b is placed on the conductive layer 103a that constitutes the electrode 103. The conductive layer 103b is placed on the conductive layer 104a of the electrode 104. This is a step of forming a conductive layer 104b (see FIG. 9(B)).

[0451] In this embodiment, the conductive layers 101a and 103a, which have a function of reflecting light, 104a, and 101b, respectively, are provided on the conductive layers 101b, 103b, and By forming 104b, the electrodes 101, 103, and 104 are formed. The conductive layers 101b, 103b, and 104b are formed using ITSO films.

[0452] The conductive layers 101b, 103b, and 104b having a function of transmitting light are formed multiple times. By forming the microcapsules in several steps, it is possible to form the microcapsules in each area. The conductive layers 101b, 103b, and 104b can be formed to a thickness that provides a void structure. Cut.

[0453] <Third step> The third step is to form the partition walls 145 that cover the ends of the electrodes of the light-emitting element. See Figure 9(C).

[0454] The partition 145 has an opening so as to overlap with the electrode. In this embodiment, the partition wall 145 is made of a polyimide resin. Use fat.

[0455] In the first to third steps, the EL layer (layer containing an organic compound) may be damaged. Since there is no risk, various film formation methods and microfabrication techniques can be applied. The method uses a sputtering method to form a reflective conductive layer, and uses a lithography method to form the conductive layer. A pattern is formed on the conductive layer, and then the pattern is formed by dry or wet etching. The conductive layer is processed into an island shape, forming a conductive layer 101a constituting the electrode 101 and an electrode 10 A conductive layer 103a constituting the electrode 3 and a conductive layer 104a constituting the electrode 104 are formed. Thereafter, a transparent conductive film is formed by sputtering, and then the conductive film is lithographically Then, a pattern is formed on the transparent conductive film, and then the conductive film is etched by a wet etching method. The transparent conductive film is then processed into islands to form electrodes 101, 103, and 104. do.

[0456] <Fourth step> The fourth step is to deposit the hole injection layer 111, the hole transport layer 112, the light emitting layer 190, the electron transport layer 113, an electron injection layer 114, and a charge generation layer 115 are formed (FIG. 10(A) reference).

[0457] The hole injection layer 111 is formed by co-evaporating a hole transporting material and a material containing an acceptor. Co-evaporation is a process in which different materials are deposited on different surfaces. The hole transport layer 112 is a deposition method in which a hole It can be formed by vapor deposition of a transport material.

[0458] The light-emitting layer 190 may be purple, blue, blue-green, green, yellow-green, yellow, orange, or red. The light-emitting layer is formed by depositing at least one luminescent guest material selected from the following: The guest material can be an organic material that emits fluorescence or phosphorescence. In addition, the light-emitting layer having the structure shown in the embodiment 1 and the embodiment 2 can be used. It is preferable that the light-emitting layer 190 is made of two layers. The light-emitting layers preferably contain light-emitting materials that emit light of different colors.

[0459] The electron transport layer 113 can be formed by evaporating a substance having a high electron transport property. The electron injection layer 114 can be formed by evaporating a material having a high electron injection property. It is possible.

[0460] The charge generating layer 115 is made of a material having a hole transporting property to which an electron acceptor is added. or a material in which an electron donor is added to an electron transporting material. It can be formed with.

[0461] <The fifth step> The fifth step is to deposit the hole injection layer 116, the hole transport layer 117, the light emitting layer 170, the electron transport layer 117, and the hole transport layer 118. 118, an electron injection layer 119, and an electrode 102 are formed (see FIG. 10B). .

[0462] The hole injection layer 116 is formed of the same material and in the same manner as the hole injection layer 111 described above. The hole transport layer 117 can be formed by the above-described hole transport layer 11. It can be formed from the same materials and in the same manner as 2.

[0463] The light-emitting layer 170 may be purple, blue, blue-green, green, yellow-green, yellow, orange, or red. The light-emitting layer is formed by depositing at least one luminescent guest material selected from the following: The guest material can be a light-emitting organic compound that exhibits fluorescence or phosphorescence. In addition, the light-emitting layer having the structure shown in the embodiment 1 and the embodiment 2 can be used. It is preferable that at least one of the light-emitting layer 170 and the light-emitting layer 190 is It is preferable that the light-emitting layer has the configuration shown in Form 1. In addition, the light-emitting layer 170 and the light-emitting layer 1 It is preferable that 90 has a light-emitting organic compound having a function of exhibiting different light emission from each other. .

[0464] The electron transport layer 118 is formed of the same material and by the same method as the electron transport layer 113 described above. The electron injection layer 119 can be formed by the above-described electron injection layer 11. It can be formed from the same materials and in the same manner as in 4.

[0465] The electrode 102 is formed by stacking a conductive film having reflectivity and a conductive film having light-transmitting properties. The electrode 102 can be formed as a single layer structure or a multilayer structure. Good too.

[0466] Through the above steps, regions 222 are formed on the electrodes 101, 103, and 104. A light emitting device having regions 222B, 222G, and 222R is formed on substrate 200.

[0467] <Sixth step> In the sixth step, a light-shielding layer 223, an optical element 224B, an optical element 224, and a This is a step of forming the optical element 224R (see FIG. 10(C)).

[0468] The light-shielding layer 223 is a resin film containing a black pigment formed in a desired area. On the plate 220 and the light-shielding layer 223, an optical element 224B, an optical element 224G, and an optical element 224C are disposed. The optical element 224B is a resin film containing a blue pigment applied to a desired area. In addition, the optical element 224G is formed by forming a resin film containing a green pigment in a desired area. In addition, the optical element 224R is formed by forming a resin film containing a red pigment in a desired area. do.

[0469] <Seventh step> The seventh step is to separate the light emitting element formed on the substrate 200 and the light emitting element formed on the substrate 2...

Claims

1. a layer having a first compound, which is a phosphorescent material, and a second compound having a function of dispersing the first compound, between a pair of electrodes; the first compound is an organometallic complex having ruthenium, rhodium, palladium, osmium, iridium, or platinum; the second compound has at least one of an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, a pyrrole skeleton, and an aromatic amine skeleton, and a π-electron-deficient heteroaromatic ring skeleton, the HOMO level of the first compound is higher than the HOMO level of the second compound; the LUMO level of the first compound is higher than the LUMO level of the second compound; an energy difference between a LUMO level of the second compound and a HOMO level of the first compound is equal to or greater than a transition energy calculated from an absorption edge in an absorption spectrum of the first compound; Light emitting element.

2. a layer having a first compound, which is a phosphorescent material, and a second compound having a function of dispersing the first compound, between a pair of electrodes; the first compound is an organometallic complex having ruthenium, rhodium, palladium, osmium, iridium, or platinum; the second compound has at least one of an indole skeleton, a carbazole skeleton, and a bicarbazole skeleton, and a π-electron-deficient heteroaromatic ring skeleton, the HOMO level of the first compound is higher than the HOMO level of the second compound; the LUMO level of the first compound is higher than the LUMO level of the second compound; an energy difference between a LUMO level of the second compound and a HOMO level of the first compound is equal to or greater than a transition energy calculated from an absorption edge in an absorption spectrum of the first compound; Light emitting element.

3. a layer having a first compound, which is a phosphorescent material, and a second compound having a function of dispersing the first compound, between a pair of electrodes; the first compound is an organometallic complex having ruthenium, rhodium, palladium, osmium, iridium, or platinum; the second compound has a bicarbazole skeleton in which two carbazolyl groups are bonded to each other at any one of the 2-position to 4-position, and a π-electron-deficient heteroaromatic ring skeleton, the HOMO level of the first compound is higher than the HOMO level of the second compound; the LUMO level of the first compound is higher than the LUMO level of the second compound; an energy difference between a LUMO level of the second compound and a HOMO level of the first compound is equal to or greater than a transition energy calculated from an absorption edge in an absorption spectrum of the first compound; Light emitting element.

4. a layer having a first compound, which is a phosphorescent material, and a second compound having a function of dispersing the first compound, between a pair of electrodes; the first compound is an organometallic complex having ruthenium, rhodium, palladium, osmium, iridium, or platinum; The second compound has a dibenzofuran skeleton and a π-electron-deficient heteroaromatic ring skeleton, the HOMO level of the first compound is higher than the HOMO level of the second compound; the LUMO level of the first compound is higher than the LUMO level of the second compound; an energy difference between a LUMO level of the second compound and a HOMO level of the first compound is equal to or greater than a transition energy calculated from an absorption edge in an absorption spectrum of the first compound; Light emitting element.

5. a layer having a first compound, which is a phosphorescent material, and a second compound having a function of dispersing the first compound, between a pair of electrodes; the first compound is an organometallic complex having ruthenium, rhodium, palladium, osmium, iridium, or platinum; the second compound has at least one of an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, a pyrrole skeleton, and an aromatic amine skeleton, and a π-electron-deficient heteroaromatic ring skeleton, the HOMO level of the first compound is higher than the HOMO level of the second compound; the LUMO level of the first compound is higher than the LUMO level of the second compound; an energy difference between a LUMO level of the second compound and a HOMO level of the first compound is equal to or greater than the energy of light emitted by the first compound; Light emitting element.

6. a layer having a first compound, which is a phosphorescent material, and a second compound having a function of dispersing the first compound, between a pair of electrodes; the first compound is an organometallic complex having ruthenium, rhodium, palladium, osmium, iridium, or platinum; the second compound has at least one of an indole skeleton, a carbazole skeleton, and a bicarbazole skeleton, and a π-electron-deficient heteroaromatic ring skeleton, the HOMO level of the first compound is higher than the HOMO level of the second compound; the LUMO level of the first compound is higher than the LUMO level of the second compound; an energy difference between a LUMO level of the second compound and a HOMO level of the first compound is equal to or greater than the energy of light emitted by the first compound; Light emitting element.

7. a layer having a first compound, which is a phosphorescent material, and a second compound having a function of dispersing the first compound, between a pair of electrodes; the first compound is an organometallic complex having ruthenium, rhodium, palladium, osmium, iridium, or platinum; the second compound has a bicarbazole skeleton in which two carbazolyl groups are bonded to each other at any one of the 2-position to 4-position, and a π-electron-deficient heteroaromatic ring skeleton, the HOMO level of the first compound is higher than the HOMO level of the second compound; the LUMO level of the first compound is higher than the LUMO level of the second compound; an energy difference between a LUMO level of the second compound and a HOMO level of the first compound is equal to or greater than the energy of light emitted by the first compound; Light emitting element.

8. a layer having a first compound, which is a phosphorescent material, and a second compound having a function of dispersing the first compound, between a pair of electrodes; the first compound is an organometallic complex having ruthenium, rhodium, palladium, osmium, iridium, or platinum; The second compound has a dibenzofuran skeleton and a π-electron-deficient heteroaromatic ring skeleton, the HOMO level of the first compound is higher than the HOMO level of the second compound; the LUMO level of the first compound is higher than the LUMO level of the second compound; an energy difference between a LUMO level of the second compound and a HOMO level of the first compound is equal to or greater than the energy of light emitted by the first compound; Light emitting element.

9. In any one of claims 5 to 8, A light-emitting device, wherein the energy of the light emitted by the first compound is derived from an emission peak wavelength on the shortest wavelength side among emission peaks (maximum or shoulder) of an emission spectrum.

10. In any one of claims 5 to 8, A light-emitting element, wherein the energy of the light emitted by the first compound is derived from a rising wavelength on the shortest wavelength side of an emission spectrum.

11. In any one of claims 1 to 10, The light-emitting device, wherein the π-electron-deficient heteroaromatic ring skeleton is at least one of a diazine skeleton and a triazine skeleton.

12. In any one of claims 1 to 10, The light-emitting device, wherein the π-electron-deficient heteroaromatic ring skeleton is at least one of a pyrimidine skeleton, a pyrazine skeleton, and a pyridazine skeleton.

13. In any one of claims 1 to 10, The light-emitting device, wherein the π-electron-deficient heteroaromatic ring skeleton is a condensed heterocyclic skeleton having a diazine skeleton.

14. In any one of claims 1 to 10, The light-emitting device, wherein the π-electron-deficient heteroaromatic ring skeleton is a benzofuropyrimidine skeleton or a benzothienopyrimidine skeleton.

15. A light-emitting element according to any one of claims 1 to 14, At least one of a color filter or a transistor; A display device having the above configuration.

16. The light-emitting device includes first to sixth transistors and a light-emitting element, one of a source and a drain of the first transistor is electrically connected to a first wiring; one of a source and a drain of the second transistor is electrically connected to a second wiring; one of a source and a drain of the third transistor is electrically connected to the other of the source and the drain of the first transistor; one of a source and a drain of the third transistor is electrically connected to the other of the source and the drain of the second transistor; one of a source and a drain of the fourth transistor is electrically connected to the other of the source and the drain of the third transistor; the other of the source and the drain of the fourth transistor is electrically connected to the gate of the third transistor; one of a source and a drain of the fifth transistor is electrically connected to the other of the source and the drain of the third transistor; the other of the source and the drain of the fifth transistor is electrically connected to the light emitting element; one of a source and a drain of the sixth transistor is electrically connected to a third wiring; the other of the source and the drain of the sixth transistor is electrically connected to the gate of the third transistor; The display device, wherein the light-emitting element is the light-emitting element according to claim 1 .

17. A display device according to claim 15 or 16, At least one of a housing or a touch sensor; An electronic device having the

18. A light-emitting element according to any one of claims 1 to 14, At least one of a housing or a touch sensor; A lighting device having the above structure.

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