Host material for light-emitting layer, light-emitting element, light-emitting device, illumination device, and electronic apparatus

Abstract

To provide a light-emitting element including a light-emitting material and having high luminous efficiency.SOLUTION: A light-emitting element includes a host material and a guest material. The host material includes a first organic compound and a second organic compound. In the first organic compound, the difference between the singlet excitation energy level and the triplet excitation energy level is more than 0 eV and 0.2 eV or less. One of the first organic compound and the second organic compound has the HOMO level that is more than or equal to the HOMO level of the other of the first organic compound and the second organic compound and the LUMO level that is more than or equal to the LUMO level of the other of the first organic compound and the second organic compound. The first organic compound and the second organic compound form an exciplex.SELECTED DRAWING: Figure 1

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. It also has the advantage of having a high response speed.

[0005] 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 an optical element (for example, an organic electroluminescence (EL) element), a negative electrode is generated by applying a voltage between a pair of electrodes. Electrons are injected from the electrode and holes are injected from the anode into the EL layer, causing a current to flow. The injected electrons and holes are then recombined to excite the light-emitting organic material. This results in an excited 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 depends on the energy of the singlet excited state. However, in a light-emitting element using an organic material that emits phosphorescence, the triplet excitation energy is The energy of light is converted into the energy of light. Therefore, the singlet excited state and triplet excited state formed by organic materials are When the energy difference between the excited and excited states is large, the energy required to excite the organic material is The energy of the emitted light is higher by the amount of energy corresponding to the energy difference. The difference between the energy required to excite the material and the energy required to emit light is The increase in driving voltage affects the element characteristics, but we have been investigating methods to suppress the increase in driving voltage. Development is currently underway for this purpose (see Patent Document 2).

[0008] In addition, among light-emitting elements using phosphorescent materials, light-emitting elements that emit blue light, However, it is difficult to develop stable materials with high triplet excitation energy levels, so they are not yet in practical use. Therefore, light-emitting devices using more stable fluorescent materials are being developed. Therefore, methods to improve the luminous efficiency of light-emitting elements using fluorescent materials (fluorescent light-emitting elements) are being explored. do.

[0009] As a material capable of converting part of the energy of the triplet excited state into luminescence, thermally activated Thermally Activated Delayed Fluorescence Thermally activated delayed fluorescent materials (TADF) are known. A singlet excited state is generated by reverse intersystem crossing from the nucleus, and the singlet excited state is converted to luminescence. .

[0010] In order to increase the luminous efficiency of a light-emitting device using a thermally activated delayed phosphor, In delayed fluorescent materials, not only is the singlet excited state efficiently generated from the triplet excited state, The advantage is that the singlet excited state can be efficiently used for luminescence, i.e., the fluorescence quantum yield is high. However, it is difficult to design a light-emitting material that satisfies both of these requirements at the same time. do.

[0011] Therefore, in a light-emitting device having a thermally activated delayed phosphor and a fluorescent material, A method in which the singlet excitation energy of a phosphor is transferred to a fluorescent material, and light is emitted from the fluorescent material. A method has been proposed (see Patent Document 3). [Prior art documents] [Patent documents]

[0012] [Patent Document 1] JP 2010-182699 A [Patent Document 2] JP 2012-212879 A [Patent Document 3] JP 2014-45179 A Summary of the Invention [Problem to be solved by the invention]

[0013] In a light-emitting device having a thermally activated delayed phosphor and a light-emitting material, the luminous efficiency is improved. Alternatively, in order to reduce the driving voltage, it is necessary to efficiently transfer carriers in the thermally activated delayed phosphor. Recombination is preferred.

[0014] In addition, in a light-emitting device having a thermally activated delayed phosphor and a fluorescent material, the luminous efficiency is improved. In order to achieve this, it is preferable that the singlet excited state is efficiently generated from the triplet excited state. In addition, the singlet excited state of the thermally activated delayed fluorescent material can be efficiently converted to the singlet excited state of the fluorescent material. It is preferred that energy is transferred.

[0015] Therefore, in one embodiment of the present invention, a light-emitting device having a fluorescent material or a phosphorescent material and high luminous efficiency is provided. Another object of the present invention is to provide an optical element having reduced power consumption. Another object of the present invention is to provide a light-emitting element having a novel Another object of the present invention is to provide a light-emitting element. Another object of the present invention is to provide a novel display device. One of our goals is to provide

[0016] 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]

[0017] One embodiment of the present invention is a light-emitting element that has a light-emitting layer in which an exciplex is efficiently formed. The method involves converting triplet excitons into singlet excitons and emitting light from a material that has singlet excitons. Alternatively, the light emitting material can emit light by the energy transfer of the singlet exciton. It is a light-emitting element that can emit light from a light source.

[0018] Therefore, one embodiment of the present invention is a light-emitting element having a host material and a guest material. The host material includes a first organic compound and a second organic compound, and the guest material includes The first organic compound has a function of exhibiting fluorescence, and the second organic compound has a singlet excited energy level the difference between the energy level and the triplet excited energy level is greater than 0 eV and 0.2 eV or less; One of the organic compound and the second organic compound is a first organic compound and a second organic compound. and the first organic compound and the second organic compound have a HOMO level equal to or higher than the HOMO level of the other of the first organic compound and the second organic compound. It is a light-emitting element having a LUMO level equal to or higher than the other LUMO level of the organic compound.

[0019] Another embodiment of the present invention is a light-emitting element including a host material and a guest material. The host material has a first organic compound and a second organic compound, and the guest material has The first organic compound has a function of being capable of exhibiting fluorescence, and has a singlet excited energy level and the triplet excited energy level is greater than 0 eV and not greater than 0.2 eV, One of the first organic compound and the second organic compound is A first organic compound and a second organic compound each having an oxidation potential equal to or higher than the oxidation potential of the other organic compound. The light-emitting element has a reduction potential equal to or higher than the other reduction potential.

[0020] Another embodiment of the present invention is a light-emitting element including a host material and a guest material. The host material has a first organic compound and a second organic compound, and the guest material has The first organic compound has a function of converting triplet excitation energy into luminescence, The difference between the singlet excited energy level and the triplet excited energy level is greater than 0 eV and less than 0.2 eV or less, and one of the first organic compound and the second organic compound is and the HOMO level of the second organic compound is equal to or higher than the HOMO level of the other of the first organic compound. The organic compound and the second organic compound have a LUMO level equal to or higher than the LUMO level of the other. It is an optical element.

[0021] Another embodiment of the present invention is a light-emitting element including a host material and a guest material. The host material has a first organic compound and a second organic compound, and the guest material has The first organic compound has a function of converting triplet excitation energy into luminescence, The difference between the singlet excited energy level and the triplet excited energy level is greater than 0 eV and less than 0.2 eV or less, and one of the first organic compound and the second organic compound is and the second organic compound has an oxidation potential equal to or higher than the other oxidation potential of the first organic compound. The light-emitting element has a reduction potential equal to or higher than the reduction potential of the other of the first organic compound and the second organic compound.

[0022] In each of the above structures, an exciplex is formed by the first organic compound and the second organic compound. It is preferable to form

[0023] That is, another aspect of the present invention is a compound having a host material and a guest material. The present invention relates to a light-emitting device comprising a first organic compound and a second organic compound, and the guest material exhibits fluorescence. The first organic compound has a function of being able to convert a singlet excited energy level into a triplet excited energy level. The difference between the first and second organic compounds and the second energy level is greater than 0 eV and 0.2 eV or less. The light-emitting element is a light-emitting element that forms an exciplex with the organic compound of formula 2.

[0024] Another embodiment of the present invention includes a host material and a guest material, The compound has a first organic compound and a second organic compound, and the guest material has a triplet excitation energy The first organic compound has a function of converting singlet excitation energy into light emission. The difference between the -level and the triplet excited energy level is greater than 0 eV and less than or equal to 0.2 eV, The light-emitting element forms an exciplex with a first organic compound and a second organic compound.

[0025] In each of the above configurations, the exciplex has a function of exhibiting thermally activated delayed fluorescence at room temperature. In addition, the exciplex has a function of donating excitation energy to the guest material. In addition, the emission spectrum of the exciplex is preferably smaller than the absorption spectrum of the guest material. It is preferable that the absorption band has a region overlapping with the absorption band on the lowest energy side.

[0026] In each of the above configurations, the first organic compound has a function of exhibiting thermally activated delayed fluorescence at room temperature. It is preferable that the function be

[0027] In each of the above structures, one of the first organic compound and the second organic compound is a hole The other of the first organic compound and the second organic compound has a function of transporting It is preferable that the first organic compound and the second organic compound have a function of transporting electrons. One of the second organic compounds has a π-electron rich heteroaromatic skeleton or an aromatic amine skeleton. the other of the first organic compound and the second organic compound is a π-electron deficient complex. It is preferable that the first organic compound has a heteroaromatic skeleton. At least one of a π-electron deficient heteroaromatic skeleton or an aromatic amine skeleton, It is preferable to have rank.

[0028] In the above structure, the π-electron-rich heteroaromatic skeleton is an acridine skeleton, a phenoxy skeleton, Sazine skeleton, phenothiazine skeleton, furan skeleton, thiophene skeleton, and pyrrole skeleton. The π-electron deficient heteroaromatic skeleton is selected from the group consisting of diazidoaryl, ... It is preferable that the compound has a pyrrole skeleton, an indole skeleton, or a triazine skeleton. carbazole skeleton, or 3-(9-phenyl-9H-carbazol-3-yl )-9H-carbazole skeleton.

[0029] Another embodiment of the present invention is a light-emitting element having any of the above structures, and a color filter or a transistor. and at least one of a first transistor and a second transistor. The electronic device has the display device and at least one of a housing and a touch sensor. Another embodiment of the present invention is a display device including a light-emitting element having any of the above structures and at least one housing or a touch sensor. Another embodiment of the present invention is a lighting device having a light-emitting element. The present invention includes not only optical devices but also electronic devices having light-emitting devices. The light-emitting device referred to here refers to an image display device or a light source (including a lighting device). The device has a connector, such as FPC (Flexible Printed Circuit ), and a display module with a TCP (Tape Carrier Package) attached A display module with a printed wiring board at the end of the TCP, or a light-emitting element with CO A display model in which IC (integrated circuit) is directly mounted using the G (Chip On Glass) method. The module may also include a light emitting device. Effect of the Invention

[0030] According to one embodiment of the present invention, a light-emitting element which includes a fluorescent material or a phosphorescent material and has high emission efficiency is provided. 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 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.

[0031] 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]

[0032] [Figure 1] 1A and 1B are schematic cross-sectional views of a light-emitting element of one embodiment of the present invention and a diagram illustrating the correlation between energy levels in a light-emitting layer. [Diagram 2] 1A and 1B are diagrams illustrating the correlation of energy bands in a light-emitting layer of a light-emitting element according to one embodiment of the present invention. [Diagram 3] 1A and 1B are diagrams illustrating the correlation of energy levels in a light-emitting layer of a light-emitting element according to one embodiment of the present invention. [Figure 4] 1A and 1B are schematic cross-sectional views of a light-emitting element of one embodiment of the present invention and a diagram illustrating the correlation between energy levels in a light-emitting layer. [Diagram 5] 1A and 1B are schematic cross-sectional views of a light-emitting element of one embodiment of the present invention and a diagram illustrating the correlation between energy levels in a light-emitting layer. [Figure 6] 1 is a schematic cross-sectional view of a light-emitting element according to one embodiment of the present invention. [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] FIG. 1 is a perspective view illustrating a display device according to one embodiment of the present invention. [Diagram 32] 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 33] FIG. 1 is a cross-sectional view illustrating a light-emitting device according to one embodiment of the present invention. [Diagram 34] 1A to 1C illustrate a lighting device and an electronic device according to one embodiment of the present invention. [Diagram 35] 1A to 1C are diagrams illustrating a lighting device according to one embodiment of the present invention. [Diagram 36] FIG. 13 is a graph showing luminance-current density characteristics of a light-emitting element in the example. [Figure 37] FIG. 13 is a graph showing luminance-voltage characteristics of a light-emitting element in the example. [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 power efficiency vs. luminance characteristics of a light-emitting element in the embodiment. [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. 2 is a graph showing electroluminescence spectra of light-emitting elements according to an embodiment of the present invention. [Diagram 42] FIG. 4 is a diagram illustrating an emission spectrum of a thin film according to an embodiment. [Diagram 43] FIG. 4 is a diagram illustrating an emission spectrum of a thin film according to an embodiment. [Diagram 44] FIG. 4 is a diagram illustrating an emission spectrum of a thin film according to an embodiment. [Diagram 45] FIG. 4 is a diagram illustrating an emission spectrum of a thin film according to an embodiment. [Diagram 46] FIG. 4 is a diagram illustrating an emission spectrum of a thin film according to an embodiment. [Figure 47] FIG. 4 is a diagram illustrating an emission spectrum of a thin film according to an embodiment. [Figure 48] FIG. 4 is a diagram illustrating an emission spectrum of a thin film according to an embodiment. [Figure 49] FIG. 2 is a diagram illustrating an NMR chart of a compound according to a reference example. [Figure 50] FIG. 2 is a diagram illustrating an NMR chart of a compound according to a reference example. [Figure 51] FIG. 2 is a diagram illustrating an NMR chart of a compound according to a reference example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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:

[0038] 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" or "singlet excited energy" is used. Even when written as "energy level," it refers to the lowest singlet excited state or S1 level. In addition, when simply written as triplet excited state or triplet excited energy level, Even though it may be the lowest triplet excited state or T1 level.

[0039] 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.

[0040] In addition, the emission energy of thermally activated delayed fluorescence is the shortest wavelength side emission energy of thermally activated delayed fluorescence. It can be derived from the peak (including the shoulder). The triplet excitation energy is the shortest wavelength emission peak (including shoulder) of phosphorescence emission. It should be noted that the phosphorescence emission occurs in a low temperature (for example, 10 K) environment. This can be observed by performing time-resolved photoluminescence.

[0041] In this specification and the like, room temperature refers to any temperature between 0°C and 40°C.

[0042] In this specification, the blue wavelength region refers to a wavelength region of 400 nm or more and less than 490 nm. blue emission is an emission spectrum having at least one emission spectrum peak in that wavelength region. The green wavelength region is the wavelength region between 490 nm and 580 nm. and green emission is emission having at least one emission spectrum peak in this wavelength region. The red wavelength region is the wavelength region between 580nm and 680nm. Red light emission is light emission having at least one emission spectrum peak in the wavelength region. do.

[0043] (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.

[0044] <Example of the configuration of light-emitting element> First, the structure of a light-emitting element according to one embodiment of the present invention will be described with reference to FIGS. The following explains this.

[0045] FIG. 1A is a schematic cross-sectional view of a light-emitting element 150 of one embodiment of the present invention.

[0046] 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. .

[0047] 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 .

[0048] 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. .

[0049] 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. Reduce the barrier, improve the transportability of holes or electrons, or inhibit 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

[0050] 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. 1B includes a host material 131 and a guest material 132. The host material 131 includes an organic compound 131_1 and an organic compound 131_2.

[0051] In addition, a light-emitting organic material may be used as the guest material 132. The material is preferably a material capable of emitting fluorescence (hereinafter, also referred to as a fluorescent material). In the following description, a fluorescent material is used as the guest material 132. The guest material 132 may be interpreted as a fluorescent material.

[0052] 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. Excitons are formed by the recombination of carriers (electrons and holes). The ratio of singlet excitons to triplet excitons (hereafter referred to as exciton generation probability) is statistically Therefore, in a light-emitting element using a fluorescent material, the ratio of the emission The ratio of singlet excitons that contribute to luminescence is 25%, and the ratio of triplet excitons that do not contribute to luminescence is 1. Therefore, the ratio of triplet excitons that do not contribute to light emission to those that do contribute to light emission is 75%. It is important to convert the excitons into singlet excitons that contribute to the emission of light in order to improve the emission efficiency of light-emitting devices. It is.

[0053] <Light Emitting Mechanism of Light Emitting Device> Next, the light emitting mechanism of the light emitting layer 130 will be described below.

[0054] The organic compound 131_1 and the organic compound 131_2 contained in the host material 131 in the light-emitting layer 130 The substance 131_2 is an exciplex (exciplex, exciplex or excipl Forms a cyclic endothelium (also called ex).

[0055] The combination of organic compound 131_1 and organic compound 131_2 forms an exciplex. Any combination that can transport holes is acceptable, but one of them must have the function of transporting holes (hole transport property). The other is a compound that has the function of transporting electrons (electron transport property). is more preferable. In this case, a donor-acceptor type exciplex is easily formed, It is possible to efficiently form an exciplex.

[0056] In addition, as a combination of organic compound 131_1 and organic compound 131_2, one of them is The other Highest Occupied Molecular Orbit It has a HOMO level equal to or higher than the lowest unoccupied molecular orbital (HOMO) level of the other (Lowest Unoccupied Molecular Orbital, LUM It is preferred that the LUMO level be equal to or higher than the LUMO level (also referred to as O).

[0057] For example, the organic compound 131_1 has a hole transporting property, and the organic compound 131_2 has an electron transporting property. When the organic compound 131_1 has the above-mentioned property, as shown in the energy band diagram in FIG. 2(A), The HOMO level of the organic compound 131_2 is equal to or higher than the HOMO level of the organic compound 131_2. The LUMO level of 131_1 is preferably equal to or higher than the LUMO level of the organic compound 131_2. Alternatively, the organic compound 131_2 has a hole transporting property, and the organic compound 131_1 has a When the organic compound has electron transport properties, as shown in the energy band diagram of FIG. The HOMO level of 31_2 is equal to or higher than the HOMO level of the organic compound 131_1, and The LUMO level of the organic compound 131_2 is equal to or higher than the LUMO level of the organic compound 131_1. In this case, it is preferable that the organic compound 131_1 and the organic compound 131_2 are used as the organic compound 131_2. An exciplex roughly corresponds to the energy difference between the HOMO level of one atom and the LUMO level of the other atom. It becomes an exciplex with excitation energy. Also, the HOMO level of the organic compound 131_1 and Difference between the HOMO level of organic compound 131_2 and the LUMO level of organic compound 131_1 The difference between the LUMO level of the organic compound 131_2 and that of the organic compound 131_2 is preferably 0.2 eV or more. , and more preferably 0.3 eV or more. 131_1) represents organic compound 131_1, and Host(131_2) represents organic compound 13 This is the notation and symbol for 1_2.

[0058] In addition, based on the relationship between the HOMO level and the LUMO level described above, the organic compound 131_1 and As for the combination with the organic compound 131_2, one of them has an oxidation potential higher than the oxidation potential of the other. It is preferable that one of the two has a reduction potential equal to or higher than the reduction potential of the other.

[0059] For example, the organic compound 131_1 has a hole transporting property, and the organic compound 131_2 has an electron transporting property. When the organic compound 131_1 has the oxidation potential, the oxidation potential of the organic compound 131_2 is and the reduction potential of the organic compound 131_1 is less than or equal to the reduction potential of the organic compound 131_2. Alternatively, the organic compound 131_2 has a hole transporting property and is preferably at most 100 nm. When the organic compound 131_1 has an electron transport property, the oxidation potential of the organic compound 131_2 is The oxidation potential of the organic compound 131_1 is equal to or less than the reduction potential of the organic compound 131_2. It is preferable that the oxidation potential is equal to or lower than the reduction potential of the organic compound 131_1. The position can be measured by a cyclic voltammetry (CV) method.

[0060] In addition, the combination of organic compound 131_1 and organic compound 131_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.

[0061] In addition, the organic compound 131_1 is preferably a thermally activated delayed fluorescent material. It is preferable that the compound has a function of exhibiting thermally activated delayed fluorescence at room temperature. The organic compound 131_1 can independently convert from the triplet excited state to the singlet excited state by reverse intersystem crossing. To achieve this, the singlet excitation energy level and the triplet excitation energy level must be It is preferable that the difference between the energy level of the organic compound and the energy level of the organic compound is greater than 0 eV and less than or equal to 0.2 eV. 131_1 is required to have the function of converting triplet excitation energy into singlet excitation energy. It is preferable that the compound does not exhibit thermally activated delayed fluorescence.

[0062] The organic compound 131_1 has a structure including a skeleton having a hole transporting property and a skeleton having an electron transporting property. In addition, the organic compound 131_1 preferably has a π-electron-rich heteroaromatic at least one of a π-electron deficient heteroaromatic skeleton and an aromatic amine skeleton, It is preferable that the heteroaromatic skeleton has a π-electron rich structure and a π-electron deficient structure. By directly bonding with the aromatic skeleton, the donor properties of the π-electron-rich heteroaromatic skeleton and the π-electron-deficient heteroaromatic skeleton are enhanced. The acceptor properties of the heteroaromatic skeleton are also strengthened, and the singlet excited energy levels and triplet excited energy levels are This is particularly preferred because the difference in the excitation energy levels is small. Due to its strong donor and acceptor properties, organic compound 131_1 and organic compound It is easy to form a donor-acceptor type exciplex with 131_2.

[0063] In addition, the distribution of the HOMO molecular orbitals and the LUMO in organic compound 131_1 It is preferable that the overlap with the region in which the molecular orbitals are distributed is small. The spatial distribution of electrons in a molecule can be expressed by the molecular orbital, and the probability of finding an electron can be expressed by the molecular orbital. It is possible to describe in detail the electronic configuration of a molecule (the spatial distribution and energy of electrons). be.

[0064] The exciplex formed by organic compound 131_1 and organic compound 131_2 is The organic compound has a HOMO molecular orbital and the other organic compound has a LUMO molecular orbital. In other words, the overlap between the HOMO molecular orbital and the LUMO molecular orbital is very small. The excited complex has a smaller difference between the singlet and triplet excited energy levels. Therefore, the exciplex formed by organic compound 131_1 and organic compound 131_2 is The difference between the doublet excitation energy level and the singlet excitation energy level is preferably greater than 0 eV. The effective energy is less than 0.2 eV.

[0065] Here, the organic compound 131_1 and the organic compound 131_2 in the light-emitting layer 130 are The energy level correlation with the photoresist material 132 is shown in FIG. The notations and symbols used are as follows: ·Host(131_1): Host material (organic compound 131_1) ·Host(131_2): Host material (organic compound 131_2) Guest(132): Guest material 132 (fluorescent material) ·S H1 : S1 level of the host material (organic compound 131_1) T H1 : T1 level of the host material (organic compound 131_1) ·S H2 : S1 level of the host material (organic compound 131_2) T H2 : T1 level of the host material (organic compound 131_2) ·S G : S1 level of guest material 132 (fluorescent material) T G : T1 level of guest material 132 (fluorescent material) ·S E : S1 level of the exciplex T E :T1 level of the exciplex

[0066] In the light-emitting element of one embodiment of the present invention, the organic compound 131_1 in the light-emitting layer 130 The organic compound 131_2 forms an exciplex. The S1 level of the exciplex (S E ) and exciplexes T1 level (T E ) are adjacent energy levels (Figure 1(C) Route E See 3).

[0067] An exciplex is an excited state consisting of two substances. In the case of photoexcitation, They are formed by the interaction of one substance with another substance in its ground state, and When the two substances that formed the exciplex reach the ground state by emitting light, In the case of electrical excitation, when one of them becomes excited, it quickly Alternatively, one atom can transfer a hole and the other an electron. The electrons can then be absorbed and interact to rapidly form exciplexes. In this case, in either substance, an exciplex is formed without forming an excited state by itself. Therefore, most of the excited states formed in the light-emitting layer 130 are exciplexes. The excited energy level of the exciplex (S E and T E )teeth, Organic compounds that form exciplexes (Organic Compound 131_1 and Organic Compound 131_2) The S1 level of (S H1 and S H2 ) is lower, so the host can be excited at a lower energy. This allows the material 131 to be excited. The dynamic voltage can be reduced.

[0068] The S1 level of the exciplex (S E ) and T1 level (T E ) are adjacent energy levels Therefore, exciplexes have the function of exhibiting thermally activated delayed fluorescence. The doublet excitation energy is converted to singlet excitation energy by reverse intersystem crossing (upconversion). (See route E4 in FIG. 1C). A part of the triplet excitation energy generated in the exciplex is converted to singlet excitation energy by the exciplex. To achieve this, the S1 level (S E ) and T1 level (T E ) energy difference is preferably greater than 0 eV and equal to or less than 0.2 eV.

[0069] In addition, the S1 level of the exciplex (S E ) is the S1 level (S G ) higher In this way, the singlet excitation energy of the generated exciplex is preferably The S1 level of the body (S E ) to the S1 level (S G ) energy transfer to As a result, the guest material 132 enters a singlet excited state and emits light (FIG. 1(C) ) See Route E5).

[0070] In order to efficiently emit light from the singlet excited state of the guest material 132, the guest material 13 It is preferable that the fluorescence quantum yield of 2 is high. Specifically, it is preferable that the fluorescence quantum yield is 50% or more, and more preferably 50% or more. It is preferably 70% or more, and more preferably 90% or more.

[0071] In order to efficiently cause reverse intersystem crossing, the T1 level (T E ) but encouragement The organic compounds that form the catalytic complexes (organic compound 131_1 and organic compound 131_2) T1 level (T H1 and T H2 ) is preferable. This allows each organic compound This makes it difficult for triplet excitation energy of the exciplex to be quenched by the ion beam, and efficiently achieves reverse intersystem exchange. Differences arise.

[0072] For example, in at least one of the compounds that form an exciplex, the S1 level and the T1 level When the difference between the T1 level and the T2 level is large, the T1 level of the exciplex (T E ) is further increased from the T1 level of each compound. The energy level must be as low as possible. The difference between the S1 and T1 levels of the exciplex is It is preferable that the S1 level of the guest material is smaller than the S1 level of the exciplex. When the difference between the S1 level and the T1 level of at least one of the compounds is large, the high Materials with a doublet excited energy level, i.e., high emission energy, e.g., blue It becomes difficult to use a material that emits light as the guest material 132.

[0073] On the other hand, in one embodiment of the present invention, the organic compound 131_1 has an S1 level (S H1 ) and T1 Level (TH1 ) is small. Therefore, the S1 and T1 levels of the organic compound 131_1 It is possible to simultaneously increase both the T1 level of the exciplex. Therefore, one embodiment of the present invention is not limited to the emission color of the guest material 132, but may be, for example, blue. From emission with high emission energy such as red to emission with low emission energy such as red Therefore, it can be suitably used for light emitting elements exhibiting various types of light emission.

[0074] In addition, when the organic compound 131_1 has a skeleton with a strong donor property, it is injected into the light-emitting layer 130. The holes are easily injected into the organic compound 131_1 and transported. Compound 131_2 is an acceptor having stronger acceptor properties than organic compound 131_1. It is preferable that the organic compound 131_1 and the organic compound 131_2 have a cyclic skeleton. _2 easily forms an exciplex. Alternatively, the organic compound 131_1 acts as an acceptor. When the organic compound 131 has a highly viscous skeleton, the electrons injected into the light-emitting layer 130 are transferred to the organic compound 131_1. At this time, organic compound 131_2 is easily injected and transported. It is preferable that the donor skeleton has a stronger donor property than 1. The compound 131_1 and the organic compound 131_2 are likely to form an exciplex.

[0075] In addition, the organic compound 131_1 can condense triplet excitation energy by reverse intersystem crossing by itself. The organic compound 131_1 has a function of converting the organic compound 131_1 into a doublet excited energy, When it is difficult to form an exciplex with 31_2, for example, H of organic compound 131_1 The OMO level of the organic compound 131_2 is higher than the HOMO level of the organic compound 131_ When the LUMO level of 2 is higher than the LUMO level of the organic compound 131_1, the luminescent layer 130 The injected carriers, electrons and holes, are both injected into the organic compound 131_1 and transported. In this case, the hole transport property and the electron transport property of the organic compound 131_1 make it easier to transport the Therefore, it is necessary to control the carrier balance in the light-emitting layer 130. 131_1 has the function of converting triplet excitation energy to singlet excitation energy by itself. In addition, the molecular structure must have a favorable carrier balance. On the other hand, in one embodiment of the present invention, the organic compound 131_ 1 and organic compound 131_2 are injected with electrons and the other with holes, and then transported. The carrier balance can be easily controlled by the mixture ratio, and high luminescence efficiency can be achieved. It is possible to provide a light emitting device that exhibits a light emitting efficiency.

[0076] For example, the HOMO level of the organic compound 131_2 is the same as that of the organic compound 131_1. The LUMO level of the organic compound 131_1 is higher than the O level of the organic compound 131_2. When the LUMO level is higher than the LUMO level, the electrons and holes that are the carriers injected into the light-emitting layer 130 Both are easily injected into organic compound 131_2 and transported. Therefore, organic compound 131 In _2, carrier recombination is likely to occur. Organic compound 131_2 alone exhibits reverse intersystem crossing. When the compound does not have a function of converting triplet excitation energy into singlet excitation energy by The triplet excitation energy of the exciton generated directly by carrier recombination is converted to the singlet excitation energy. Therefore, it is difficult to convert the electrons directly into electron energy by carrier recombination. Of the excitons, it is difficult to utilize the energy of any other than the singlet excitation for light emission. In one embodiment, an exciplex is formed between organic compound 131_1 and organic compound 131_2. The triplet excitation energy is converted to singlet excitation energy by reverse intersystem crossing. Therefore, it is possible to provide a light emitting element having high luminous efficiency and high reliability. can.

[0077] In FIG. 1(C), the S1 level of the organic compound 131_2 is the same as the S 1 level, and the T1 level of organic compound 131_1 is higher than the T1 level of organic compound 131_2. However, one embodiment of the present invention is not limited to this. As shown in Fig. 1, the S1 level of organic compound 131_1 is higher than the S1 level of organic compound 131_2. Even if the T1 level of organic compound 131_1 is higher than the T1 level of organic compound 131_2, Alternatively, as shown in FIG. 3B, the S1 level of the organic compound 131_1 and the organic The S1 level of the compound 131_2 may be the same. Thus, the S1 level of organic compound 131_2 is higher than the S1 level of organic compound 131_1. It does not matter if the T1 level of organic compound 131_2 is higher than the T1 level of organic compound 131_1. In either case, however, in order to efficiently cause reverse intersystem crossing, the excitation The T1 level of the complex is calculated by the following equation for each organic compound that forms an exciplex (organic compound 131_1 and organic It is preferable that the T1 level is lower than that of the compound 131_2). In the process, reverse intersystem crossing first occurs in organic compound 131_1, and organic compound 131_ The singlet excited state of 1 (S H1 After the proportion of singlet The exciplex (S E(having an energy level of In this case, the T1 level ( T H1 ) than the T1 level of organic compound 131_2 (T H2 ) is preferably larger Therefore, the configuration in FIG. 3(C) is preferable.

[0078] In addition, the S1 level of the exciplex (S E ) from the T1 level (T G ) to The energy transfer is direct from the singlet ground state to the triplet excited state in the guest material 132. Since the transition is forbidden, it is unlikely to be the dominant energy transfer process.

[0079] In addition, the T1 level of the exciplex (T E ) to the T1 level (T G ) to triplet When excitation energy transfer occurs, the triplet excitation energy is deactivated (Figure 1(C) (See Route E6.) Therefore, the smaller the energy transfer in Route E6, the more favorable the guest material 1 is. The generation efficiency of the triplet excited state of 32 can be reduced, and thermal deactivation can be reduced. For this purpose, the weight ratio of the host material 131 to the guest material 132 is preferably It is preferable that the weight ratio of the guest material 132 is low. The weight ratio of the resin material 132 is preferably 0.001 or more and 0.05 or less, more preferably Preferably, the ratio is 0.001 or more and 0.03 or less, and more preferably, the ratio is 0.001 or more and 0.01 or less. .

[0080] In addition, when the direct recombination process of carriers becomes dominant in the guest material 132, the light-emitting layer At 130, a large number of triplet excitons are generated, and the emission efficiency is reduced due to thermal deactivation. Therefore, rather than the direct recombination of carriers in the guest material 132, The energy transfer process via the formation of an exciplex (Routes E4 and E5 in Fig. 1(C)) The more the number of bonds, the lower the generation efficiency of the triplet excited state of the guest material 132 can be. This is preferable because it is possible to suppress deactivation. The weight ratio of the guest material 132 to the host material 132 is preferably low. The weight ratio of the guest material 132 to the host material 131 is 0.001 or more and 0. 05 or less, more preferably 0.001 to 0.03, and further preferably Between 0.001 and 0.01 inclusive.

[0081] As described above, all of the energy transfer processes in routes E4 and E5 described above occur efficiently. For example, both the singlet excitation energy and the triplet excitation energy of the host material 131 can be efficiently converted to the Since the energy of the singlet excited state of the guest material 132 is converted into the energy of the singlet excited state of the guest material 132, the light-emitting element 150 It becomes possible to emit light with high luminous efficiency.

[0082] The above-mentioned routes E3, E4, and E5 are referred to as ExSET ( Exciplex-Singlet Energy Transfer (ExEF) (Exciplex-Enhanced Fluorescence) In other words, the light-emitting layer 130 converts the excitation energy from the exciplex into the guest material 132. There is provision of.

[0083] By configuring the light-emitting layer 130 as described above, light emission from the guest material 132 in the light-emitting layer 130 can be obtained efficiently.

[0084] <Energy transfer mechanism> Next, the control of the energy transfer process between the host material 131 and the guest material 132 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). Here, energy transfer between the host material 131 and the guest material 132 is The process is similar when the host material 131 is an exciplex.

[0085] <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 131 and the guest material 132. The host material 131 transfers energy to the guest material 132 due to the resonance phenomenon of the dipole vibration. The excited host material 131 goes to the ground state, and the guest material 13 2 becomes excited. The rate constant of the Förster mechanism is k h*→g is shown in formula (1). .

[0086]

number

[0087] In formula (1), ν represents the frequency, and f' h (ν) is the standard value of the host material 131 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 132, N represents Avogadro's number, and n represents the refractive index of the medium, and R represents the intermolecular distance between the host material 131 and the guest material 132. where τ is the measured lifetime of the excited state (fluorescence lifetime or phosphorescence lifetime), c is the speed of light, φ is the luminescence quantum yield (fluorescence quantum yield when considering energy transfer from a singlet excited state) , and phosphorescence quantum yield when discussing energy transfer from triplet excited states), and K 2 teeth, Coefficient (from 0 to 4) In the case of random orientation, K 2 =2 / 3.

[0088] <Dexter System> In the Dexter mechanism, the host material 131 and the guest material 132 are bonded together with orbital overlap. The electrons of the host material 131 in the excited state and the guest material 13 in the ground state approach each other within the effective distance of each other. Energy transfer occurs through the exchange of electrons with 2. The rate constant for the Dexter mechanism is k h*→g is shown in formula (2).

[0089]

number

[0090] 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 131. 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 132, L represents the effective molecular radius, R represents the intermolecular distance between the host material 131 and the guest material 132 .

[0091] Here, the energy transfer efficiency φ from the host material 131 to the guest material 132 ET is a number It is expressed by equation (3). r The emission process of the host material 131 (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 and intersystem crossing) of the host material 131. represents the rate constant, and τ represents the measured lifetime of the excited state of the host material 131.

[0092]

number

[0093] From equation (3), the energy transfer efficiency φ ET 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.

[0094] <Concept for improving energy transfer> First, consider the energy transfer via the Förster mechanism. Substituting equation (1) into equation (3), Therefore, in the case of the Förster mechanism, the energy Energy transfer efficiency φ ET does not depend on the lifetime τ of the excited state of the host material 131. Energy transfer efficiency φ ET is the emission quantum yield φ (which discusses the energy transfer from the singlet excited state) Therefore, it is better to have a higher fluorescence quantum yield. The luminescence quantum yield from the excited state is very low at room temperature. In the case of the doublet excited state, the energy transfer process by the Förster mechanism can be neglected, and the phosphatase This need only be taken into consideration when the photocatalytic material 131 is in a singlet excited state.

[0095] In addition, the emission spectrum of the host material 131 (energy transfer from the singlet excited state is discussed) The fluorescence spectrum (when the fluorescence occurs) and the absorption spectrum (from the singlet ground state to the It is preferable that the overlap with the absorption corresponding to the transition to the singlet excited state is large. It is preferable that the molar extinction coefficient of the guest material 132 is also high. This means that the emission spectrum overlaps with the absorption band appearing on the longest wavelength side of the guest material 132. In addition, the direct transition from the singlet ground state to the triplet excited state in the guest material 132 Since the transition is forbidden, the molar absorptivity coefficient associated with the triplet excited state in the guest material 132 is This suggests that the number of ions in the guest material 132 is negligible due to the Förster mechanism. The energy transfer process to the doublet excited state is negligible, and the energy transfer to the singlet excited state of the guest material 132 is In other words, in the Förster mechanism, only the energy transfer process of The energy from the singlet excited state of the host material 131 to the singlet excited state of the guest material 132 Just think about the process of movement.

[0096] Next, consider the energy transfer via the Dexter mechanism. According to equation (2), the rate constant is k h*→g In order to increase the emission spectrum of the host material 131 (from the singlet excited state), When discussing energy transfer, the fluorescence spectrum) and the absorption spectrum of the guest material 132 ( The larger the overlap with the absorption corresponding to the transition from the singlet ground state to the singlet excited state, the better. Therefore, the optimization of the energy transfer efficiency is important for the emission of the host material 131. The spectrum overlaps with the absorption band appearing on the longest wavelength side of the guest material 132. It will be realized.

[0097] In addition, by substituting formula (2) into formula (3), the energy transfer in the Dexter mechanism is Efficiency φ ET It can be seen that depends on τ. The Dexter mechanism is an energy mechanism based on electron exchange. Since this is a quantum dot transfer process, the electrons are transported from the singlet excited state of the host material 131 to the singlet excited state of the guest material 132. Similar to the energy transfer to the triplet excited state of the host material 131, the guest Energy transfer to the triplet excited state of the charge transport material 132 also occurs.

[0098] In the light-emitting element of one embodiment of the present invention, the guest material 132 is a fluorescent material. It is preferable that the efficiency of energy transfer to the triplet excited state of the cation material 132 is low. The energy transfer effect based on the Dexter mechanism from the host material 131 to the guest material 132 The rate is preferably low, and the Förster mechanism from the host material 131 to the guest material 132 is It is preferable that the efficiency of energy transfer based on

[0099] As mentioned above, the efficiency of energy transfer in the Förster mechanism is dependent on the host material. The lifetime of the excited state of 1 does not depend on τ. On the other hand, the efficiency of energy transfer in the Dexter mechanism is depends on the excitation lifetime τ of the host material 131. Therefore, the energy In order to reduce the energy transfer efficiency, it is preferable that the excitation lifetime τ of the host material 131 is short. It is nice.

[0100] In addition, in the same manner as the energy transfer from the host material 131 to the guest material 132, an exciplex The energy transfer process from the nucleus to the guest material 132 was also investigated using the Förster mechanism and the Deca- Energy transfer occurs via both mechanisms of the star mechanism.

[0101] Therefore, one embodiment of the present invention is to provide an energy transfer system capable of efficiently transferring energy to the guest material 132. The combination of organic compounds that form exciplexes that function as electron donors. A light-emitting element having a host material 131 containing the organic compound 131_1 and an organic compound 131_2 is provided. The exciplex formed by organic compound 131_1 and organic compound 131_2 is a singlet excited electron complex. The feature of this compound is that the triplet excited energy level is close to the triplet excited energy level. Therefore, the transition from triplet excitons to singlet excitons (reverse intersystem crossover) generated in the light-emitting layer 130 Therefore, the efficiency of generating singlet excitons in the light-emitting layer 130 is increased. Furthermore, it is possible to convert the singlet excited state of the exciplex into an energy acceptor. In order to facilitate energy transfer to the singlet excited state of the guest material 132, the excitation The emission spectrum of the complex and the guest material 132, which appears on the longest wavelength side (lowest energy side). It is preferable that the absorption band of the guest material 132 overlaps with that of the singlet excited state. The production efficiency can be improved.

[0102] In addition, the fluorescence lifetime of the thermally activated delayed fluorescence component of the emission from the exciplex is short. Specifically, it is preferable that the period is 10 ns or more and 50 μs or less, and more preferably, 10 ns or more and 3 It is less than 0 μs.

[0103] In addition, it has been found that the proportion of thermally activated delayed fluorescence components in the emission of exciplexes is high. Specifically, it is preferable that the proportion of the thermally activated delayed fluorescence component in the emission of the exciplex is 100%. The proportion is preferably 5% or more, and more preferably 10% or more.

[0104] <Material> Next, components of a light-emitting element according to one embodiment of the present invention will be described in detail below.

[0105] <Light-emitting layer> The materials that can be used for the light-emitting layer 130 are described below.

[0106] In the light-emitting layer 130, the host material 131 is present in the largest amount by weight, and the guest material 132 The (fluorescent material) is dispersed in the host material 131. The S1 level of the organic compound 131_1 and the organic compound 131_2 is the guest It is preferable that the S1 level of the material 132 (fluorescent material) is higher than that of the material 132. The T1 level of the photoresist material 131 (organic compound 131_1 and organic compound 131_2) is It is preferably higher than the T1 level of the guest material 132 (fluorescent material) of the layer 130.

[0107] The organic compound 131_1 converts triplet excitation energy to singlet excitation by reverse intersystem crossing. It is preferable that the compound has a function of converting energy into heat and exhibits thermally activated delayed fluorescence at room temperature. It is preferable that the triplet excitation energy is converted into singlet excitation energy. The material that can be used is a thermally activated delayed fluorescent material. When the material is selected from the group consisting of the above, the following materials can be used, for example:

[0108] 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. Porphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-fluoride Tin complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (Sn F2 (Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride Complex (SnF2(Copro III-4Me)), Octaethylporphyrin-fluoride Tin complex (SnF2(OEP)), etioporphyrin-tin fluoride complex (SnF2(E tio I)), octaethylporphyrin-platinum chloride complex (PtCl2OEP), etc. Can be obtained.

[0109] [ka]

[0110] In addition, as a thermally activated delayed fluorescent material composed of one kind of material, π-electron-rich heteroaromatic Heterocyclic compounds having an aromatic skeleton and a π-electron deficient heteroaromatic skeleton can also be used. Specifically, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[ 2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-T RZ), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-3-yl 4,6-diphenyl-1,3,5-triazine (abbreviation Name: PCCzPTzn), 2-[4-(10H-phenoxazin-10-yl)phenyl ]-4,6-diphenyl-1,3,5-triazine (abbreviation: PXZ-TRZ), 3-[4 -(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5- Diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-di Methyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACR XTN), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl] Sulfone (abbreviation: DMAC-DPS), 10-phenyl-10H,10'H-spiro[a Clizin-9,9'-anthracene]-10'-one (abbreviation: ACRSA) and the like. The heterocyclic compound has a π-electron rich heteroaromatic skeleton and a π-electron deficient heteroaromatic skeleton. Since they have a high electron transporting property and hole transporting property, they are preferred. Among aromatic skeletons, diazine skeletons (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), The triazine skeleton is preferred because it is stable and has good reliability. Among the aromatic skeletons, the acridine skeleton, the phenoxazine skeleton, the phenothiazine skeleton, and the furazolide skeleton are The thiophene skeleton, pyrrole skeleton, and pyrrole skeleton are stable and reliable. It is preferable that the compound has one or more selected from the following: As the alkyl group, an indole skeleton or a carbazole skeleton is preferable, and 3-(9-phenyl-9H- Carbazol-3-yl)-9H-carbazole skeleton is particularly preferred. A substance in which a π-rich heteroaromatic skeleton and a π-electron-deficient heteroaromatic skeleton are directly bonded is a π-electron-rich The donor properties of the π-type heteroaromatic skeleton and the acceptor properties of the π-electron-deficient heteroaromatic skeleton are both strong. In this case, the difference between the singlet excitation energy level and the triplet excitation energy level becomes small, and therefore, I wish.

[0111] [ka]

[0112] In addition, the organic compound 131_1 converts triplet excitation energy to singlet excitation energy by reverse intersystem crossing. It is sufficient that the compound has a function of converting photoinduced energy into photoinduced energy, and does not have a function of exhibiting thermally activated delayed fluorescence. In this case, the organic compound 131_1 may have a π-electron-rich heteroaromatic skeleton or an aromatic At least one of the aromatic amine skeleton and the π-electron deficient heteroaromatic skeleton is an m-phenylene group. or having a structure in which the bond is formed via a structure having at least one o-phenylene group. Alternatively, at least one of an m-phenylene group and an o-phenylene group is preferably It is preferable that the arylene group has a structure in which the bond is formed via an arylene group having a biphenyl group. It is more preferable that the phenylene group is used. In this way, the T1 level of the organic compound 131_1 is In this case, the π-electron-deficient heteroaromatic skeleton can be , diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), or triazine The π-electron-rich heteroaromatic skeleton is preferably an acridine skeleton, Phenoxazine skeleton, phenothiazine skeleton, furan skeleton, thiophene skeleton, and pyrrole It is preferable that the cyclic alkyl group has one or more of the following skeletons: The skeleton is a dibenzofuran skeleton, and the thiophene skeleton is a dibenzothiophene skeleton. As the pyrrole skeleton, an indole skeleton and a carbazole skeleton are preferable. is preferred, and 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazol The aromatic amine skeleton is preferably a so-called aromatic amine skeleton having no NH bond. Tertiary amines having a triarylamine skeleton are preferred, and triarylamine skeletons are particularly preferred. The aryl group in the skeleton is a substituted or unsubstituted aryl group having 6 to 13 carbon atoms forming a ring. Preferred are phenyl, naphthyl and fluorenyl groups.

[0113] Examples of the aromatic amine skeleton and the π-electron-rich heteroaromatic skeleton include the following general compounds: The skeletons are represented by the formulae (101) to (117). 6) X represents an oxygen atom or a sulfur atom.

[0114] [ka]

[0115] Examples of the π-electron deficient heteroaromatic skeleton include those represented by the following general formulas (201) to (202). The skeleton is represented as (218).

[0116] [ka]

[0117] 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 A bond having at least one m-phenylene group or o-phenylene group In the case where the bond is formed via a group, or at least one of an m-phenylene group or an o-phenylene group In the case where the bond is formed via a bonding group having an arylene group having the following formula, an example of the bonding group is The skeleton is represented by the following general formulas (301) to (314). Examples of the phenylene skeleton, biphenyldiyl skeleton, naphthalenediyl skeleton, fluorene skeleton, Examples of the skeleton include a diyl skeleton and a phenanthrenediyl skeleton.

[0118] [ka]

[0119] The aromatic amine skeleton (specifically, triarylamine skeleton), π-electron-rich heterostructure Aromatic skeleton (specifically, acridine skeleton, phenoxazine skeleton, phenothiazine skeleton, orthocyclic, thiophene, or pyrrole skeletons), π-electron-deficient heteroaromatic skeletons ( Specifically, the ring having a diazine skeleton or a triazine skeleton) or the above general formula (1 01) to (117), general formulae (201) to (218), and general formulae (301) to ( 314) may have a substituent. The substituent may be a group having 1 to 6 carbon atoms. an alkyl group, a cycloalkyl group having 3 to 6 carbon atoms, or a cycloalkyl group having 6 to 12 carbon atoms; A substituted or unsubstituted aryl group having 1 to 10 carbon atoms can also be selected as a substituent. Specific examples of the alkyl group having 6 carbon atoms include a methyl group, an ethyl group, a propyl group, and an isopropyl group. Examples of the aryl group include butyl, isobutyl, tert-butyl, and n-hexyl groups. Specific examples of the cycloalkyl group having 3 to 6 carbon atoms include cycloalkyl groups such as Examples of the cyclopropyl group, the cyclobutyl group, the cyclopentyl group, the cyclohexyl group, etc. The aryl group having 6 to 12 carbon atoms can be a phenyl group, a naphthyl group, or the like. Specific examples of the substituents include a phenyl group, a biphenyl group, etc. They may be bonded to form a ring. Examples of such a ring include the fluorene skeleton. When the carbon atom at position 9 has two phenyl groups as substituents, the phenyl groups are bonded to each other. In this case, a spirofluorene skeleton is formed. In the case of the compound (a), it is advantageous in terms of ease of synthesis and the cost of the raw materials.

[0120] In addition, Ar represents an arylene group having 6 to 13 carbon atoms, and the arylene group is an unsubstituted 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 phenylene 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 5 carbon atoms. an alkyl group having 3 to 6 carbon atoms, a cycloalkyl group having 6 to 6 carbon atoms, or An aryl group having 1 to 6 carbon atoms can also be selected as a substituent. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group. , isobutyl group, tert-butyl group, n-hexyl group, etc. Specific examples of the cycloalkyl group having 3 to 6 carbon atoms include a cyclopropyl group, a cycloalkyl group, and a cycloalkyl group having 3 to 6 carbon atoms. Examples of the alkyl 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. The following can be given as specific examples.

[0121] The arylene group represented by Ar is, for example, the following structural formula (Ar-1) to (Ar- 18) can be used. The groups that can be used as Ar are Not limited to these.

[0122] [ka]

[0123] Also, R 1 and R 2 each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; a cycloalkyl group having 3 to 6 carbon atoms, or a substituted or unsubstituted cycloalkyl group having 6 to 13 carbon atoms; represents an unsubstituted aryl group. Examples of the alkyl group having 1 to 6 carbon atoms include Specifically, methyl, ethyl, propyl, isopropyl, butyl, and isobutyl groups. , tert-butyl group, n-hexyl group, etc. Specific examples of the cycloalkyl group having 6 carbon atoms include a cyclopropyl group and a cyclobutyl group. cyclopentyl, cyclohexyl, and the like. Examples of aryl groups having 13 carbon atoms include phenyl, naphthyl, biphenyl, and fluorenyl. Specific examples of the aryl group and the phenyl group are also given. may have a substituent, and the substituents may be bonded to each other to form a ring. 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 C6 to C12 aryl group or an aryl group 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 the like. butyl, isobutyl, tert-butyl, n-hexyl Examples of the cycloalkyl group having 3 to 6 carbon atoms include: Specifically, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, etc. Examples of the aryl group having 6 to 12 carbon atoms include phenyl. Specific examples include a phenyl group, a naphthyl group, and a biphenyl group.

[0124] Also, R 1 and R 2 The alkyl group or aryl group represented by the following structural formula ( Groups represented by R-1) to (R-29) can be used. The groups that can be used as the aryl group are not limited to these.

[0125] [ka]

[0126] In addition, the general formulae (101) to (117), (201) to (218), and ( 301) to (314), and Ar, R 1 and R 2 The substituents which may be substituted include, for example, For example, the alkyl group or aryl group represented by the above structural formulas (R-1) to (R-24) may be used. The alkyl or aryl group can be selected from the group consisting of: Not limited to these.

[0127] In the light-emitting layer 130, the guest material 132 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: .

[0128] 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.

[0129] As described above, the host material 131 (or the exciplex) is converted into the guest material 132. It is preferable that the efficiency of energy transfer based on the Dexter mechanism is low. The rate constant is inversely proportional to the exponential function of the distance between the two molecules. Below 1 nm, the Dexter mechanism predominates, and above approximately 1 nm, the Förster mechanism predominates. Therefore, in order to reduce the efficiency of energy transfer in the Dexter mechanism, For this purpose, it is preferable to increase the distance between the host material 131 and the guest material 132. Specifically, the thickness is preferably 0.7 nm or more, more preferably 0.9 nm or more, and even more preferably From this viewpoint, the guest material 132 is preferably close to the host material 131. It is preferable that the compound has a substituent that inhibits adhesion, and the substituent is preferably an aliphatic hydrocarbon. Preferably, it is an alkyl group, more preferably, a branched alkyl group. Specifically, the guest material 132 has at least two alkyl groups having two or more carbon atoms. Alternatively, the guest material 132 may be an arsenic compound having a branch with 3 to 10 carbon atoms. Preferably, the guest material 132 has at least two alkyl groups. It is preferable that the alkyl group has at least two cycloalkyl groups having 3 to 10 cycloalkyl groups.

[0130] The organic compound 131_2 is a compound capable of forming an exciplex with the organic compound 131_1. Specifically, in addition to zinc and aluminum metal complexes, oxadiazole derivatives , triazole derivatives, benzimidazole derivatives, quinoxaline derivatives, dibenzoquinoline Xaline derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, pyrimidine derivatives , triazine derivatives, pyridine derivatives, bipyridine derivatives, phenanthroline derivatives, etc. Other examples include aromatic amines and carbazole derivatives. In this case, the emission of an exciplex formed by organic compound 131_1 and organic compound 131_2 The peak corresponds to the absorption band on the longest wavelength side (lowest energy side) of the guest material 132 (fluorescent material). In an overlapping manner, organic compound 131_1, organic compound 131_2, and guest material 132 It is preferable to select a fluorescent material. This will dramatically improve the luminous efficiency. It can be an element.

[0131] As the organic compound 131_2, the following hole transporting material and electron transporting material are used: It can be used.

[0132] 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.

[0133] As examples of materials with high hole transport properties, aromatic amine compounds include N,N' -Di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDP PA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino ]biphenyl (abbreviation: DPAB), N,N'-bis{4-[bis(3-methylphenyl) Amino]phenyl}-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-di Amine (abbreviation: DNTPD), 1,3,5-tris[N-(4-diphenylaminophenyl Examples include]-N-phenylamino]benzene (abbreviation: DPA3B).

[0134] 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.

[0135] 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.

[0136] 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) phenyl)anthracene (abbreviation: t-BuDBA), 9,10-di(2-naphthyl)anthracene 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.

[0137] 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.

[0138] 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.

[0139] As a material with high hole transport properties, for example, 4,4'-bis[N-(1-naphthyl )-N-phenylamino]biphenyl (abbreviation: NPB or α-NPD) and N,N'-biphenyl S(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4 '-Diamine (abbreviation: TPD), 4,4',4''-tris(carbazol-9-yl) Triphenylamine (abbreviation: TCTA), 4,4',4''-tris[N-(1-naphthalene 1'-TNATA, 4,4'-N-phenylamino]triphenylamine ,4''-Tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA ), 4,4',4''-tris[N-(3-methylphenyl)-N-phenylamino] Triphenylamine (abbreviation: MTDATA), 4,4'-bis[N-(spiro-9,9'- Bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 4- Phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: B PAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenyl 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}phenylamine (abbreviation: DFLADFL), N-(9,9-dimethyl-2-diphenylamino-9H-fluorenyl) Fluoren-7-yl)diphenylamine (abbreviation: DPNF), 2-[N-(4-diphenyl N-phenylaminophenyl)spiro-9,9'-bifluorene (abbreviation: D PASF), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl) PCBA1BP, 4,4'-diphenyl-4''-(9-phenyl) (phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP ), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl) Triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-( 9-Phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNB) B) 4-phenyldiphenyl-(9-phenyl-9H-carbazol-3-yl)amine N,N'-bis(9-phenylcarbazol-3-yl)- N,N'-Diphenylbenzene-1,3-diamine (abbreviation: PCA2B), N,N',N ''-Triphenyl-N,N',N''-tris(9-phenylcarbazol-3-yl) ) Benzene-1,3,5-triamine (abbreviation: PCA3B), N-(4-biphenyl)- N-(9,9-dimethyl-9H-fluoren-2-yl)-9-phenyl-9H-carba PCBiF, N-(1,1'-biphenyl-4-yl)- N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl 9,9-Dimethyl-N- Phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluor PCBAF, N-phenyl-N-[4-(9-phenyl- 9H-carbazol-3-yl)phenyl]spiro-9,9'-bifluorene-2-amine PCBASF, 2-[N-(9-phenylcarbazol-3-yl)-N- Phenylamino]spiro-9,9'-bifluorene (abbreviation: PCASF), 2,7-bis [N-(4-diphenylaminophenyl)-N-phenylamino]-spiro-9,9'- Bifluorene (abbreviation: DPA2SF), N-[4-(9H-carbazol-9-yl)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) (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 DBTFLP-III, 4-[4-(9-phenyl-9H-fluorene-9 -yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), 4-[3-(triphenylen-2-yl)phenyl]dibenzothiophene (abbreviation: mDB TPTp-II) and other amine compounds, carbazole compounds, thiophene compounds, furan compounds Compounds, fluorene compounds, triphenylene compounds, phenanthrene compounds, etc. The substances mentioned here are mainly 1×10 -6 cm 2 / Vs or higher hole mobility However, other materials that have a higher hole transporting property than electron transporting property can be used. It may be used.

[0140] As the electron transport material, a material having a higher electron transporting property than a hole transporting property can be used. ×10 -6 cm 2 It is preferable that the material has an electron mobility of 1 / Vs or more. Nitrogen-containing heteroaromatic compounds are examples of materials that are easy to absorb (materials with electron transport properties). A π-electron deficient heteroaromatic compound or a metal complex can be used. Quinoline, benzoquinoline, oxazole, or thiazole ligands Metal complexes having the same, oxadiazole derivatives, triazole derivatives, phenanthroline derivatives Examples of the compound include conductors, pyridine derivatives, bipyridine derivatives, and pyrimidine derivatives.

[0141] For example, tris(8-quinolinolato)aluminum(III) (abbreviation: Alq), tri Bis(4-methyl-8-quinolinolato)aluminum(III) (abbreviation: Almq3), BeBq2 ), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum ( III) (abbreviation: BAlq), bis(8-quinolinolato)zinc(II) (abbreviation: Znq) Metal complexes having a quinoline skeleton or a benzoquinoline skeleton, etc. Bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO) , Bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ) Metal complexes having oxazole or thiazole ligands such as In addition to metal complexes, 2-(4-biphenylyl)-5-(4-tert-butyl phenyl)-1,3,4-oxadiazole (abbreviation: PBD) and 1,3-bis[5-( p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazole-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-triazole -3-yl)phenyl]-9H-carbazole (abbreviation: CzTAZ1), '-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazo 2-[3-(dibenzothiophene-4-yl)phenyl]-1 -Phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), bathophenane Troline (abbreviation: BPhen), Bathocuproine (abbreviation: BCP), 2,9-bis(naphthalene) phthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NB Heterocyclic compounds such as 2-[3-(dibenzothiophen-4-yl)phenyl] 1,2-[3' -(Dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]kinoki Sarin (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazole-9 -yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBP DBq), 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl ]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(di Benzothiophene-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7m DBTPDBq-II) and 6-[3-(dibenzothiophen-4-yl)phenyl ]Dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 2-[3-( 3,9'-bi-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxa Phosphorus (abbreviation: 2mCzCzPDBq), 4,6-bis[3-(phenanthren-9-yl) )phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-diphenyl 4,6mDBTP2Pm-II, 6-Bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6 Heterocyclic compounds with diazine skeletons such as PCCzPTzn Heterocyclic compounds with triazine skeletons and 3,5-bis[3-(9H-carbazole-9 -yl)phenyl]pyridine (abbreviation: 35DCzPPy), 1,3,5-tri[3-(3 -pyridyl)phenyl]benzene (abbreviation: TmPyPB) The heterocyclic compound, 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene ( Heteroaromatic compounds such as BzOs can also be used. Among them, diazine (pyrimidine, pyrazine, pyridazine) skeleton or pyridine skeleton are Heterocyclic compounds having such a skeleton are preferred because they are stable and have good reliability. The heterocyclic compound has high electron transport properties and contributes to reducing the driving voltage. lysinediyl) (abbreviation: PPy), poly[(9,9-dihexylfluorene-2,7-di yl)-co-(pyridine-3,5-diyl)] (abbreviation: PF-Py), poly[(9,9 -dioctylfluorene-2,7-diyl)-co-(2,2'-bipyridine-6,6' A polymer compound such as PF-BPy (abbreviation: PF-BPy) can also be used. The substances mentioned in are mainly 1×10 -6 cm 2 It is a material that has an electron mobility of 0.1V or more. Note that any substance other than the above may be used as long as it has a higher electron transporting property than a hole transporting property. .

[0142] The light-emitting layer 130 may be formed of two or more layers. When the light-emitting layer 130 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.

[0143] In addition, in the light-emitting layer 130, materials other than the host material 131 and the guest material 132 are It is acceptable to have one.

[0144] <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).

[0145] 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: F4-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.

[0146] 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 carbenes mentioned as examples of hole transport materials that can be used in the light-emitting layer 130 are Bazole derivatives, aromatic hydrocarbons, stilbene derivatives, etc. can also be used. The hole transporting material may be a polymer compound.

[0147] <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 HOM of the hole injection layer 111 has a function of transporting the injected holes to the light emitting layer 130. It is preferred that the HOMO level be the same as or close to the O level.

[0148] 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.

[0149] ≪Electron transport layer≫ The electron transport layer 118 is connected to the other of the pair of electrodes (electrode 101 or The material has a function of transporting electrons injected from the electrode 102 to the light-emitting layer 130. A material with a higher electron transport capacity than holes can be used as the -6 cm 2 It is preferable that the material has an electron mobility of 100 / Vs or more. As materials with electron transport properties, π-electron-deficient compounds such as nitrogen-containing heteroaromatic compounds are Heteroaromatic compounds and metal complexes can be used. The quinoline ligand, benzoquinoline ligand, and the like, which are listed as examples of electron transporting materials that can be used, Metal complexes having an oxazole ligand or a thiazole ligand are also included. Oxadiazole derivatives, triazole derivatives, phenanthroline derivatives, pyridine derivatives Examples of the derivatives include pyrimidine derivatives, bipyridine derivatives, and pyrimidine derivatives. -6 cm 2 It is preferable that the material has an electron mobility of 1 / Vs or more. Any substance other than the above may be used for the electron transport layer as long as it has a high transportability. The electron transport layer 118 may be a single layer or a stack of two or more layers made of the above substances.

[0150] In addition, a layer for controlling the movement of electron carriers is provided between the electron transport layer 118 and the light emitting layer 130. This is a material having a high electron transporting property and a material having a high electron trapping property. A layer in which a small amount of Zn is added, which suppresses the movement of electron carriers, thereby reducing carrier dispersion. This structure prevents electrons from penetrating the light-emitting layer. This is highly effective in suppressing problems caused by the above-mentioned problems (such as a decrease in element life).

[0151] ≪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 (LiF), sodium fluoride (NaF), and cesium fluoride (CsF ), calcium fluoride (CaF2), lithium oxide (LiO x ) and other alkaline gold Metals, alkaline earth metals, or compounds thereof can be used. A rare earth metal compound such as fluorine (ErF3) can be used. An electride may be used for 119. The electride may be, for example, calcium. Examples include a material in which electrons are highly concentrated in a mixed oxide of aluminum and ruthenium. The injection layer 119 may be made of a material that can be used in the electron transport layer 118 .

[0152] 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.

[0153] 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.

[0154] The quantum dots are classified into colloidal quantum dots, alloy quantum dots, and core-shell quantum dots. In addition, a group 2 and a group 16, a group 13 and a group 14, and a core type quantum dot may be used. Contains element groups 15, 13 and 17, 11 and 17, or 14 and 15 Quantum dots may also be used. Alternatively, cadmium (Cd), selenium (Se), zinc (Zn ), sulfur (S), phosphorus (P), indium (In), tellurium (Te), lead (Pb), gallium (Ga), Quantum dots containing elements such as Ga, Arsenic, and Aluminum are used. It's fine.

[0155] 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.

[0156] 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. It is also possible to reduce the amount of 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.

[0157] 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.

[0158] 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 zinc oxide (Indium Zinc Oxide), Indium Tin Oxide containing titanium, Indium Metal oxides such as titanium oxide, tungsten and zinc-containing indium oxide are used. In addition, the thickness of the film may be set to a level that allows light to pass through (preferably, a thickness of 1 nm to 30 nm). The metal thin film may be, for example, Ag or Ag and Al. Alloys such as Ag and Mg, Ag and Au, and Ag and Yb can be used.

[0159] 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.

[0160] 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.

[0161] 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.

[0162] 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.

[0163] 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.

[0164] 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 having a desired wavelength from each light-emitting layer and intensify the light of that wavelength. This is preferable because it has a function of adjusting the optical path so that the optical path can be adjusted.

[0165] 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.

[0166] <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.

[0167] 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.

[0168] 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 These include cellulose nanofibers (CNF), paper, and base films that contain the above materials. Examples of glass substrates include barium borosilicate glass, aluminoborosilicate glass, or Soda lime glass, etc. Flexible substrates, laminated films, base films, etc. Examples include polyethylene terephthalate (PET), poly Polyethylene naphthalate (PEN), polyethersulfone (PES), polytetrafluoroethylene Examples of plastics include PTFE (polytetrafluoroethylene). Resins such as acrylic resins are also available. Examples include polypropylene, polyester, and polypropylene. Examples include polyvinyl fluoride, polyvinyl chloride, etc., or polyamide, Examples include polyimide, aramid, epoxy, inorganic vapor deposition film, and paper.

[0169] 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.

[0170] 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.

[0171] Also, for example, a field effect transistor (FET) is formed on the above-mentioned substrate, and the FET and A light-emitting element may be fabricated on the electrically connected electrodes. This allows light emission by the FET. An active matrix type display device that controls the driving of optical elements can be manufactured.

[0172] 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, the EL layer may be formed of a host material and a fluorescent material. A guest material having a function of being able to emit light or convert triplet excitation energy into light emission. and a host material having a function of converting singlet excited energy into a singlet excited energy. The difference between the energy level and the triplet excited energy level is greater than 0 eV and less than or equal to 0.2 eV. Although an example in which the first organic compound is included is shown, one embodiment of the present invention is not limited thereto. In some cases, or depending on the circumstances, in one aspect of the invention, for example, the host material is The difference between the singlet excited energy level and the triplet excited energy level is greater than 0 eV and less than 0.2 Alternatively, the first organic compound may not have a first organic compound having a molecular weight of 0.01 eV or less. The difference between the singlet excited energy level and the triplet excited energy level is greater than 0 eV and less than 0.2 Alternatively, for example, in one embodiment of the present invention, the first organic compound and the second organic compound may be The example of forming an exciplex with the organic compound of formula 2 has been described. In some cases or depending on the situation, in one aspect of the present invention, for example, Alternatively, the first organic compound and the second organic compound may not form an exciplex. For example, in one embodiment of the present invention, one of the first organic compound and the second organic compound is and a HOMO level of the second organic compound that is equal to or higher than the HOMO level of the other of the first organic compound, And the LUMO level of the first organic compound and the second organic compound is equal to or higher than the LUMO level of the other one of the first organic compound and the second organic compound. Although an example of the case where the aryl group has a position has been shown, one embodiment of the present invention is not limited to this. Alternatively, depending on the context, in one embodiment of the invention, for example, a first organic compound and a second The first organic compound and the second organic compound are in a state where one of the organic compounds is in a state where the other of the first organic compound and the second organic compound is in a state where the other of the first organic compound is in a state where the other of ... or higher HOMO level, and the other L of the first organic compound and the second organic compound It is not necessary for the structure to have a LUMO level equal to or higher than the UMO level.

[0173] The structure shown in this embodiment mode can be used in appropriate combination with other embodiment modes. Cut.

[0174] (Embodiment 2) In this embodiment mode, a light-emitting element having a different structure from that shown in Embodiment 1 and The light emitting mechanism of the light emitting element will be described below with reference to FIGS. In FIG. 4(A), the same reference numerals as those in FIG. 1(A) denote the same parts having the same functions. In addition, parts with similar functions are designated by the hatch pattern. , the same reference numerals will be used and detailed descriptions thereof may be omitted.

[0175] <Example of the configuration of light-emitting element> FIG. 4A is a schematic cross-sectional view of a light-emitting element 152 of one embodiment of the present invention.

[0176] 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 140. .

[0177] In the light-emitting element 152, the electrode 101 functions as an anode, and the electrode 102 functions as a cathode. The following description will be given assuming that the light emitting element 152 functions as a light emitting element. I don't.

[0178] FIG. 4(B) is a schematic cross-sectional view showing an example of the light-emitting layer 140 shown in FIG. The light-emitting layer 140 shown in FIG. 1B includes a host material 141 and a guest material 142. The host material 141 includes an organic compound 141_1 and an organic compound 141_2.

[0179] In addition, a light-emitting organic material may be used as the guest material 142. The material is preferably a material capable of emitting phosphorescence (hereinafter also referred to as a phosphorescent material). In the following description, a phosphorescent material is used as the guest material 142. The guest material 142 may be interpreted as a phosphorescent material.

[0180] <Light Emitting Mechanism of Light Emitting Device> Next, the light emitting mechanism of the light emitting layer 140 will be described below.

[0181] The organic compound 141_1 and the organic compound 141_2 contained in the host material 141 in the light-emitting layer 140 The substance 141_2 forms an exciplex.

[0182] The combination of organic compound 141_1 and organic compound 141_2 forms an exciplex. Any combination is acceptable as long as one of the compounds has a hole transporting property and the other It is more preferable that the compound has an electron transporting property. In this case, This makes it easier to form a ter-type exciplex, and allows the efficient formation of exciplexes.

[0183] In addition, as a combination of organic compound 141_1 and organic compound 141_2, one of them is The HOMO level of the other molecule is equal to or higher than the HOMO level of the other molecule, and the LUMO level of the other molecule is equal to or higher than the LUMO level of the other molecule. It is preferred to have an O level.

[0184] Organic compound 1 in the energy band diagrams of FIGS. 2(A) and 2(B) explained in the first embodiment As with organic compound 31_1 and organic compound 131_2, for example, organic compound 141_1 is a hole transporter. When the organic compound 141_1 has an electron transporting property, and the organic compound 141_2 has an electron transporting property, The HOMO level of the organic compound 141_2 is equal to or higher than the HOMO level of the organic compound 141_2. The LUMO level of 41_1 is preferably equal to or higher than the LUMO level of the organic compound 141_2. Alternatively, the organic compound 141_2 has a hole transporting property, and the organic compound 141_1 has an electron transporting property. When the electron transport property is present, the HOMO level of the organic compound 141_2 is higher than that of the organic compound 141_1. The HOMO level of the organic compound 141_2 is higher than the LUMO level of the organic compound It is preferable that the LUMO level of the organic compound 141_1 is higher than the LUMO level of the organic compound 141_1. The exciplex formed by the organic compound 141_2 has a HOMO level on one side and a LUMO level on the other side. The resulting excited complex has an excitation energy roughly equivalent to the energy difference between the two levels. The difference between the HOMO level of organic compound 141_1 and the HOMO level of organic compound 141_2, and The difference between the LUMO level of organic compound 141_1 and the LUMO level of organic compound 141_2 is Each of them is preferably 0.2 eV or more, and more preferably 0.3 eV or more.

[0185] In addition, based on the relationship between the HOMO level and the LUMO level described above, the organic compound 141_1 and As for the combination with the organic compound 141_2, one of them has an oxidation potential higher than the oxidation potential of the other. It is preferable that one of the two has a reduction potential equal to or higher than the reduction potential of the other.

[0186] That is, the organic compound 141_1 has a hole transporting property, and the organic compound 141_2 has an electron transporting property. When the organic compound 141_1 has a conductivity, the oxidation potential of the organic compound 141_2 is The reduction potential of the organic compound 141_1 is equal to or lower than the reduction potential of the organic compound 141_2. Alternatively, the organic compound 141_2 has a hole transporting property, When the organic compound 141_1 has an electron transporting property, the oxidation potential of the organic compound 141_2 is The oxidation potential of the organic compound 141_1 is equal to or less than the reduction potential of the organic compound 141_2. , preferably equal to or lower than the reduction potential of the organic compound 141_1.

[0187] In addition, the combination of organic compound 141_1 and organic compound 141_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.

[0188] In addition, the organic compound 141_1 is preferably a thermally activated delayed fluorescent material. It is preferable that the compound has a function of exhibiting thermally activated delayed fluorescence at room temperature. The organic compound 141_1 can independently convert from the triplet excited state to the singlet excited state by reverse intersystem crossing. To achieve this, the singlet excitation energy level and the triplet excitation energy level must be It is preferable that the difference between the energy level of the organic compound and the energy level of the organic compound is greater than 0 eV and less than or equal to 0.2 eV. 141_1 is required to have the function of converting triplet excitation energy into singlet excitation energy. It is preferable that the compound does not exhibit thermally activated delayed fluorescence.

[0189] The organic compound 141_1 has a structure including a skeleton having a hole transporting property and a skeleton having an electron transporting property. In addition, the organic compound 141_1 preferably has a π-electron-rich heteroaromatic at least one of a π-electron deficient heteroaromatic skeleton and an aromatic amine skeleton, It is preferable that the heteroaromatic skeleton has a π-electron rich structure and a π-electron deficient structure. By directly bonding with the aromatic skeleton, the donor properties of the π-electron-rich heteroaromatic skeleton and the π-electron-deficient heteroaromatic skeleton are enhanced. The acceptor properties of the heteroaromatic skeleton are also strengthened, and the singlet excited energy levels and triplet excited energy levels are This is particularly preferred because the difference in the excitation energy levels is small. Due to its strong donor and acceptor properties, organic compound 141_1 and organic compound It is easy to form a donor-acceptor type exciplex with 141_2.

[0190] In addition, the distribution of the HOMO molecular orbitals and the LUMO in organic compound 141_1 It is preferable that the overlap with the region in which the molecular orbitals are distributed is small.

[0191] The exciplex formed by organic compound 141_1 and organic compound 141_2 is The organic compound has a HOMO molecular orbital and the other organic compound has a LUMO molecular orbital. In other words, the overlap between the HOMO molecular orbital and the LUMO molecular orbital is very small. The excited complex has a smaller difference between the singlet and triplet excited energy levels. Therefore, the exciplex formed by organic compound 141_1 and organic compound 141_2 is The difference between the doublet excitation energy level and the singlet excitation energy level is preferably greater than 0 eV. The effective energy is less than 0.2 eV.

[0192] Here, the organic compound 141_1 and the organic compound 141_2 in the light-emitting layer 140 are The correlation between the energy levels of the SiO2 and the SiO2 material 142 is shown in FIG. The notations and symbols used are as follows: ·Host(141_1): Host material (organic compound 141_1) ·Host(141_2): Host material (organic compound 141_2) Guest(142): Guest material 142 (phosphorescent material) ·S PH1 : S1 level of the host material (organic compound 141_1) T PH1 : T1 level of the host material (organic compound 141_1) ·S PH2 : S1 level of the host material (organic compound 141_2) T PH2 : T1 level of the host material (organic compound 141_2) T PG :T1 level of guest material 142 (phosphorescent material) ·S PE : S1 level of the exciplex T PE :T1 level of the exciplex

[0193] In the light-emitting element of one embodiment of the present invention, the organic compound 141_1 in the light-emitting layer 140 The organic compound 141_2 forms an exciplex. The S1 level of the exciplex (S PE ) and exciplexes The body's T1 level (T PE ) are adjacent to each other (see route E7 in Figure 4(C)). .

[0194] Organic compound 141_1 and organic compound 141_2 receive holes and electrons, respectively. When the electrons interact with each other, they quickly form an exciplex. When the electron enters the exciplex state, it quickly interacts with another electron to form an exciplex. Most of the excited states formed in the optical layer 140 exist as exciplexes. Excitation energy level (S PE and T PE) is a list of organic compounds that form exciplexes. S1 levels of organic compounds 141_1 and 141_2 (S PH1 and S PH2 ) Therefore, the excited state of the host material 141 (exciplex) is reached at a lower excitation energy. This allows the driving voltage of the light emitting element 152 to be reduced. can be done.

[0195] And the (S PE ) and (T PE ) and the energy of the guest material 142 (Phosphorescent material) to the lowest excited triplet state level, resulting in light emission (Figure 4(C) (See routes E8 and E9).

[0196] 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

[0197] By configuring the light-emitting layer 140 as described above, the guest material 142 (phosphorescent material ) can be efficiently obtained.

[0198] The above-mentioned processes of Route E7, Route E8, and Route E9 are referred to as "Route E7, Route E8, and Route E9" in this specification. ExTET (Exciplex-Triplet Energy Transfer) In other words, the light-emitting layer 140 converts the guest material 142 from the exciplex. In this case, the excitation energy is transferred to T PE From S PE Inverse Intersection to The cross-linking efficiency does not need to be high, and S PE Since the quantum yield of light emission from the A wide range of selection is possible.

[0199] The above reactions can be represented by the following general formulas (G1) to (G3).

[0200] D + +A - → (D·A) * (G1) (D A) * +G → D+A+G * (G2) G * → G+hν (G3)

[0201] In the general formula (G1), one of the organic compound 141_1 and the organic compound 141_2 has a hole. Receipt (D + ), the other accepts electrons (A - ) by using organic compound 141_1 and The organic compound 141_2 is an exciplex ((D·A) * ) is produced by the reaction of the general formula (G2) is an exciplex ((D A) * ) to the guest material 142(G) This results in an excited state of the guest material 142 (G * ) is produced by the reaction of the general formula (G As in 3), light is emitted (hν) from the guest material 142 in an excited state.

[0202] In order to efficiently transfer excitation energy from the exciplex to the guest material 142, , the T1 level of the exciplex (T PE ) are each organic compound that forms an exciplex (organic compound 14 1_1 and organic compound 141_2) T1 level (T PH1and T PH2 ) or As a result, the triplet excitation energy of the exciplex of each organic compound is Energy quenching is less likely to occur, and energy transfer to the guest material 142 occurs efficiently. do.

[0203] For example, in at least one of the compounds that form an exciplex, the S1 level and the T1 level When the difference between the T1 level and the T2 level is large, the T1 level of the exciplex (T PE ) is equivalent to the T1 level of each compound The T1 level of the guest material must be lower than that of the exciplex. It is preferable that the T level is equal to or smaller than the T level. Therefore, the S When the difference between the T1 level and the T1 level is large, the triplet excited energy level is high. A material that emits light with high emission energy, such as blue light, is used as a guest material. It will be difficult to use it as a resource 142.

[0204] On the other hand, in one embodiment of the present invention, the organic compound 141_1 has an S1 level (S PH1 ) and T 1 level (T PH1 ) is small. Therefore, the S1 level and T1 level of organic compound 141_1 It is possible to simultaneously increase both the T1 level of the exciplex. Therefore, one embodiment of the present invention is not limited to the emission color of the guest material 142, and can be, for example, Light with high emission energy such as blue, and light with low emission energy such as red The present invention can be suitably used for light emitting elements that emit various types of light, from fluorine to fluorine.

[0205] In addition, when the organic compound 141_1 has a skeleton with a strong donor property, it is injected into the light-emitting layer 140. The holes are easily injected into the organic compound 141_1 and transported. Compound 141_2 is an acceptor having a stronger acceptor property than organic compound 141_1. It is preferable that the organic compound 141_1 and the organic compound 141_2 have a cyclic skeleton. _2 easily forms an exciplex. Alternatively, organic compound 141_1 acts as an acceptor. When the organic compound 141 has a highly viscous skeleton, the electrons injected into the light-emitting layer 140 are transferred to the organic compound 141_1. At this time, organic compound 141_2 is easily injected and transported. It is preferable that the donor skeleton has a stronger donor property than 1. The compound 141_1 and the organic compound 141_2 are likely to form an exciplex.

[0206] In addition, the organic compound 141_1 can condense triplet excitation energy by reverse intersystem crossing by itself. The organic compound 141_1 has a function of converting the organic compound 141_1 into a doublet excited energy, When it is difficult to form an exciplex with 41_2, for example, H of organic compound 141_1 The OMO level of the organic compound 141_2 is higher than the HOMO level of the organic compound 141_ When the LUMO level of 2 is higher than the LUMO level of the organic compound 141_1, the light-emitting layer 140 The injected carriers, electrons and holes, are both injected into the organic compound 141_1 and transported. In this case, the hole transport property and the electron transport property of the organic compound 141_1 make it easier to transport the Therefore, it is necessary to control the carrier balance in the light-emitting layer 140. 141_1 has the function of converting triplet excitation energy to singlet excitation energy by itself. In addition, the molecular structure must have a favorable carrier balance. On the other hand, in one embodiment of the present invention, the organic compound 141_ 1 and organic compound 141_2 are injected with electrons and the other with holes, and then transported. The carrier balance can be easily controlled by the mixture ratio, and high luminescence efficiency can be achieved. It is possible to provide a light emitting device that exhibits a light emitting efficiency.

[0207] For example, the HOMO level of the organic compound 141_2 is the same as that of the organic compound 141_1. The LUMO level of the organic compound 141_1 is higher than the O level of the organic compound 141_2. When the LUMO level is higher than the LUMO level, the electrons and holes that are the carriers injected into the light-emitting layer 140 Both are easily injected into organic compound 141_2 and transported. Therefore, organic compound 141 In _2, carrier recombination is likely to occur. Organic compound 141_2 alone exhibits reverse intersystem crossing. When the compound does not have a function of converting triplet excitation energy into singlet excitation energy by The energy difference between the S1 and T1 levels of the organic compound 141_2 becomes large, so the guest The energy difference between the T1 level of the material 142 and the S1 level of the organic compound 141_2 becomes large. Therefore, the driving voltage of the light emitting element is increased by the voltage corresponding to the energy difference. On the other hand, in one aspect of the present invention, each organic compound (organic compound 141_1 and and organic compounds 141_2) with excitation energy lower than the excitation energy level of the single unit, It is possible to form an exciplex between the compound 141_1 and the organic compound 141_2. Therefore, it is possible to reduce the driving voltage of the light-emitting element, and to provide a light-emitting element with low power consumption. It can be provided.

[0208] In FIG. 4C, the S1 level of the organic compound 141_2 is the same as that of the organic compound 141_ The S1 level of organic compound 141_1 is higher than the T1 level of organic compound 141_2. However, one embodiment of the present invention is not limited to this. The S1 level of 41_1 is higher than the S1 level of organic compound 141_2, and organic compound 141_1 The T1 level of the organic compound 141_2 may be higher than the T1 level of the organic compound 141_2. It is acceptable for the S1 level of organic compound 141_1 and the S1 level of organic compound 141_2 to be comparable. Alternatively, the S1 level of organic compound 141_2 is higher than the S1 level of organic compound 141_1. Even if the T1 level of organic compound 141_2 is higher than the T1 level of organic compound 141_1, However, in either case, the T1 level of the exciplex must be at the level at which the exciplex is formed. The T1 levels of each organic compound (organic compound 141_1 and organic compound 141_2) are equivalent to or lower.

[0209] The mechanism of the energy transfer process between the host material 141 and the guest material 142 is shown in FIG. As in the first embodiment, the Förster mechanism (dipole-dipole interaction) and the Deck mechanism are This can be explained by two mechanisms: the star mechanism (electron exchange interaction) and the electron exchange mechanism. Regarding the Star mechanism and the Dexter mechanism, embodiment 1 may be referred to.

[0210] <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 discussing energy transfer from a singlet excited state) The higher the emission spectrum of the host material 141 (energy from the singlet excited state), the better. When discussing energy transfer, the fluorescence spectrum and the absorption spectrum of the guest material 142 (single It is preferable that the absorption of the triplet state overlaps with the absorption corresponding to the transition from the triplet ground state to the triplet excited state. In addition, it is preferable that the molar absorption coefficient of the guest material 142 is high. The emission spectrum of the guest material 141 and the absorption band appearing on the longest wavelength side of the guest material 142 are It means overlap.

[0211] 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 141 (energy transfer from the singlet excited state) is discussed. The fluorescence spectrum (if present) and the absorption spectrum (from the singlet ground state to the triplet state) of the guest material 142 The larger the overlap with the absorption corresponding to the transition to the excited doublet state, the better. The optimization of the energy transfer efficiency is based on the emission spectrum of the host material 141 and the emission spectrum of the guest material 142. This is achieved by overlapping with the absorption band appearing on the longest wavelength side.

[0212] In addition, in the same manner as the energy transfer from the host material 141 to the guest material 142, an exciplex The energy transfer process from the nucleus to the guest material142 was also investigated using the Förster mechanism and the Deca- Energy transfer occurs via both mechanisms of the star mechanism.

[0213] Therefore, one embodiment of the present invention is to provide an energy transfer system capable of efficiently transferring energy to the guest material 142. 141 Organic compounds that form exciplexes that function as electron donors A light-emitting element having a host material 141 made of a compound 141_1 and an organic compound 141_2 is provided. The exciplex formed by organic compound 141_1 and organic compound 141_2 is a singlet excited electron complex. The feature of this compound is that the triplet excited energy level is close to the triplet excited energy level. Therefore, the exciplex generated in the light-emitting layer 140 is composed of the organic compound 141_1 and the organic compound Therefore, the light-emitting element 152 can be formed with lower excitation energy than the light-emitting element 141_2. In addition, the driving voltage can be reduced in the exciplex. Energy transfer occurs to the triplet excited state of the guest material 142, which acts as an energy acceptor. To simplify the analysis, we first compared the emission spectrum of the exciplex with that of the longest wavelength ( It is preferable that the absorption band that appears in the lower energy side of the guest material overlaps with that in the upper energy side of the guest material. This can increase the efficiency of generating the triplet excited state of 142.

[0214] <Examples of materials that can be used for the light-emitting layer> Next, materials that can be used for the light-emitting layer 140 will be described below.

[0215] In the light-emitting layer 140, the host material 141 is present in the largest amount by weight, and the guest material 142 The phosphorescent material is dispersed in the host material 141. The T1 level of the organic compound 141_1 and the organic compound 141_2 is the guest It is preferably higher than the T1 level of the material (guest material 142).

[0216] The organic compound 141_1 preferably has a function of exhibiting thermally activated delayed fluorescence at room temperature. That is, the energy difference between the triplet excited energy level and the singlet excited energy level is Specifically, it is preferable that the triplet excitation energy level and the singlet excitation energy level are small. The energy difference from the -level is preferably greater than 0 eV and less than or equal to 0.2 eV, and more preferably The triplet excited energy level and the singlet excited energy level are greater than 0 eV and less than 0.1 eV. Thermally activated delayed fluorescent materials are examples of materials with a small energy difference from the energy level. As the thermally activated delayed fluorescent material, the materials exemplified in the first embodiment can be used. .

[0217] In addition, the organic compound 141_1 has a triplet excited energy level and a singlet excited energy level. It is sufficient that the energy difference between the position is small, and it is not necessary for the compound to have a function of exhibiting thermally activated delayed fluorescence. In this case, the organic compound 141_1 has a π-electron-rich heteroaromatic skeleton or an aromatic amine. At least one of the aromatic ring structure and the π-electron deficient heteroaromatic ring structure 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 has at least one m-phenylene group or o-phenylene group. It is preferable that the bond is formed via an arylene group, and the arylene group is a biphenyl. It is more preferable that the aryl group is a phenyl group. By doing so, the T1 level of the organic compound 141_1 can be increased. In this case, the π-electron deficient heteroaromatic skeleton can be pyrimidine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton), or triazine skeleton The π-electron-rich heteroaromatic skeleton is preferably an acridine skeleton, a pheno Xanthazine skeleton, phenothiazine skeleton, furan skeleton, thiophene skeleton, and pyrrole skeleton It is preferable that the compound has one or more selected from the following: As the alkyl group, an indole skeleton or a carbazole skeleton is preferable, and 3-(9-phenyl-9H- A carbazol-3-yl)-9H-carbazole skeleton is particularly preferred.

[0218] The organic compound 141_2 is a compound capable of forming an exciplex with the organic compound 141_1. Specifically, a zinc or aluminum metal complex or an oxadiazole derivative is preferably used. bodies, triazole derivatives, benzimidazole derivatives, quinoxaline derivatives, dibenzoxazole derivatives, Noxaline derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, pyrimidine derivatives Derivatives, triazine derivatives, pyridine derivatives, bipyridine derivatives, and phenanthroline derivatives Heteroaromatic compounds such as aryl amines, aromatic amines, and carbazole derivatives. The electron transporting material and the hole transporting material shown in the embodiment 1 can be used. In this case, The emission peak of the exciplex formed by the organic compound 141_1 and the organic compound 141_2 is Triplet MLCT (Metal to Ligand C) of guest material 142 (phosphorescent material) Absorption band of the charge transfer transition, more specifically, the absorption band on the longest wavelength side Organic compound 141_1, organic compound 141_2, and guest material 14 It is preferable to select phosphorescent material 2. This will dramatically improve the luminous efficiency. However, when a thermally activated delayed fluorescent material is used instead of a phosphorescent material, In this case, the absorption band on the longest wavelength side is preferably a singlet absorption band.

[0219] The guest material 142 (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.

[0220] 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-tris( riazolate)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), a 4H-triazole skeleton and organometallic iridium complexes having tris[3-methyl-1-(2-methylphenyl) -5-phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviation: Ir (Mptz1-mp)3), tris(1-methyl-5-phenyl-3-propyl-1H- 1,2,4-Triazolate)iridium(III) (abbreviation: Ir(Prptz1-Me) 3) and fac-triazole-based organometallic iridium complexes. S[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole] Iridium(III) (abbreviation: Ir(iPrpmi)3), tris[3-(2,6-dimethyl phenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(I II) Imidazole skeleton-containing compounds such as Ir(dmpimpt-Me)3 Organic metal iridium complexes and bis[2-(4',6'-difluorophenyl)pyridinato N,C 2’ ]Iridium(III) tetrakis(1-pyrazolyl)borate (abbreviation: FI r6), Bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]Ili Dium(III) picolinate (abbreviation: FIrpic), bis{2-[3',5'-bis (Trifluoromethyl)phenyl]pyridinato-N,C 2’}Iridium(III) pico Ir(CF3ppy)2(pic) (fluorophenyl)pyridinato-N,C 2’ ]Iridium(III) acetylacetonate (abbreviation: FIr(acac)) Among the above, 4H-triazole is an organometallic iridium complex. Organometallic iridium complexes having a skeleton are particularly preferred because of their excellent reliability and luminous efficiency. .

[0221] In addition, examples of substances having a green or yellow emission peak include tris(4-methylphenyl) Ir(mppm)3, Tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation: I r(tBuppm)3), (acetylacetonato)bis(6-methyl-4-phenylpyridine Iridium(III) (abbreviation: Ir(mppm)2(acac)), (acetylacetonate ruacetonato)bis(6-tert-butyl-4-phenylpyrimidinato)iridium( III) (abbreviation: Ir(tBuppm)2(acac)), (acetylacetonato)bis [4-(2-norbornyl)-6-phenylpyrimidinato]iridium(III) (abbreviation Ir(nbppm)2(acac)), (acetylacetonato)bis[5-methyl-6 -(2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: Ir(mpmppm)2(acac)), (acetylacetonato)bis{4,6-dimethyl 2-[6-(2,6-dimethylphenyl)-4-pyrimidinyl-κN3]phenyl- {κC}iridium(III) (abbreviation: Ir(dmppm-dmp)2(acac)), ( Acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III)( Abbreviation: Ir(dppm)2(acac) (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazine) Iridium(III) (abbreviation: Ir(mppr-Me)2(acac)), (acetylacetonate arylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinate)irid Pyrazine skeleton such as Ir(III) (abbreviation: Ir(mppr-iPr)2(acac)) Organometallic iridium complexes and tris(2-phenylpyridinato-N,C 2’ ) Iridium(III) (abbreviation: Ir(ppy)3), bis(2-phenylpyridinato-N ,C 2’ ) Iridium(III) acetylacetonate (abbreviation: Ir(ppy)2(ac ac)), bis(benzo[h]quinolinato)iridium(III) acetylacetonate (abbreviation: Ir(bzq)2(acac)), tris(benzo[h]quinolinato)iridium Ir(III) (abbreviation: Ir(bzq)3), tris(2-phenylquinolinato-N,C 2 ’ ) Iridium(III) (abbreviation: Ir(pq)3), bis(2-phenylquinolinato- N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: Ir(pq)2(ac Organometallic iridium complexes with pyridine skeletons such as bis(2,4-difluorophenyl) and Venyl-1,3-oxazolato-N,C 2’ ) Iridium(III) acetylacetoner Ir(dpo)2(acac)), bis{2-[4'-(perfluorophenyl (phenyl)pyridinato-N,C 2’}Iridium(III) acetylacetonate( Abbreviation: Ir(p-PF-ph)2(acac)), bis(2-phenylbenzothiazol -N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: Ir(bt)2(a In addition to organometallic iridium complexes such as tris(acetylacetonato)(monophenyl) Anthroline) terbium(III) (abbreviation: Tb(acac)3(Phen)) Among the above, the organometallic iridium complexes having a pyrimidine skeleton are Dium complexes are particularly preferred because they are remarkably excellent in reliability and luminous efficiency.

[0222] 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-triphenylpyrazine)(dipyridine) Valoylmethanato)iridium(III) (abbreviation: Ir(tppr)2(dpm)), ( Acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]i Pyrazine skeleton such as Ir(III) (abbreviation: [Ir(Fdpq)2(acac)]) Organometallic iridium complexes and tris(1-phenylisoquinolinato-N,C 2 ’ ) Iridium(III) (abbreviation: Ir(piq)3), bis(1-phenylisoquinoli Nat-N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: Ir(piq) In addition to organometallic iridium complexes with pyridine skeletons such as 2(acac)), 2,3, 7,8,12,13,17,18-Octaethyl-21H,23H-porphyrin platinum ( II) (abbreviation: PtOEP) and tris(1,3-diphenyl-1,3 -propanedionato)(monophenanthroline)europium(III)(abbreviation:Eu( DBM)3(Phen)), tris[1-(2-thenoyl)-3,3,3-trifluoro Acetonato](monophenanthroline)europium(III) (abbreviation: Eu(TTA) Among the above, pyrimidine skeleton complexes such as rare earth metal complexes are also useful. Organometallic iridium complexes, which have excellent reliability and luminescence efficiency, are particularly preferred. In addition, organometallic iridium complexes having a pyrazine skeleton emit red light with good chromaticity. Obtained.

[0223] 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.

[0224] 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.

[0225] The light-emitting layer 140 may be composed of two or more layers. When the light-emitting layer 140 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.

[0226] In addition, in the light-emitting layer 140, materials other than the host material 141 and the guest material 142 are It is acceptable to have one.

[0227] The light-emitting layer 140 can be formed by a deposition method (including a vacuum deposition method), an ink-jet method, a coating method, a grating method, or the like. It can be formed by a method such as rabia printing. In addition to the above-mentioned materials, quantum dots, etc. Inorganic compounds or polymeric compounds (oligomers, dendrimers, polymers, etc.) good.

[0228] The configuration described in this embodiment mode may be used in appropriate combination with the configurations described in other embodiments. There can be.

[0229] (Embodiment 3) In this embodiment, a configuration different from that shown in the first and second embodiments is developed. The optical element and the light-emitting mechanism of the light-emitting element will be described below with reference to FIGS. 5 and 6. In addition, in Fig. 5 and Fig. 6, the parts having the same functions as those shown in Fig. 1(A) are indicated by the following symbols: In some cases, the hatch patterns are similar and the reference numbers are omitted. Also, parts with similar functions The same reference numerals will be used for the same components, and detailed descriptions thereof may be omitted.

[0230] <Configuration example 1 of light-emitting element> FIG. 5A is a schematic cross-sectional view of a light-emitting element 250. FIG.

[0231] 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 the structure shown in FIG. In other words, it is preferable that the light-emitting layer 100 has a structure similar to that of the EL layer 100 shown in FIG. The element 150 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, and the electrode The following description will be given assuming that 102 functions as a cathode, but the configuration of the light-emitting element 250 is as follows: The opposite is also fine.

[0232] 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, the light-emitting unit 108 may have an EL layer 10 shown in FIG. It is preferable to use 0.

[0233] The light emitting element 250 has a light emitting layer 120 and a light emitting layer 130. In addition to the light-emitting layer 120, 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 130. 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.

[0234] 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.

[0235] 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, as in the case of the light-emitting unit 108, the surface of the light-emitting unit on the anode side is When the charge generating layer 115 is in contact with the charge generating layer 115, the charge generating layer 115 is the hole injection layer of the light emitting unit. Since the light-emitting unit can also function as a hole-transporting layer, the light-emitting unit can also include a hole-injecting layer or The hole transport layer may not be provided.

[0236] 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 containing a composite material of an organic compound and an acceptor substance and a layer containing a transparent conductive material are combined. It may also be formed by combining.

[0237] 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.

[0238] 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). If the conductivity of the charge generating layer 115 is as high as that of the pair of electrodes, the charge Carriers generated by the generation layer 115 flow in the direction of the film surface, and the electrode 101 and the electrode In some cases, light emission occurs in areas where the light emitting element 102 does not overlap. To achieve this, the charge generating layer 115 is preferably formed of a material having a lower electrical conductivity than the pair of electrodes. It is nice.

[0239] 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.

[0240] 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. .

[0241] At least one of the multiple units has an EL layer shown in FIG. By applying the configuration of 100, a light-emitting element with high luminous efficiency can be provided. do.

[0242] The light-emitting layer 130 of the light-emitting unit 108 has the structure shown in the first embodiment. In this way, the light emitting element 250 has a fluorescent material as a light emitting material, and This is preferable as it becomes a light emitting element with high luminous efficiency.

[0243] The light-emitting layer 120 of the light-emitting unit 106 may be, for example, as shown in FIG. The compound semiconductor layer 120 includes a host material 121 and a guest material 122. The guest material 122 is a fluorescent material. The fees are explained below.

[0244] <Light Emitting Mechanism of the Light Emitting Layer 120> The light emitting mechanism of the light emitting layer 120 will be described below.

[0245] 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 121 is present in a large amount compared to 22, the generation of excitons An excited state of the material 121 is formed.

[0246] An exciton is a pair of carriers (electrons and holes). Therefore, the material in which the excitons are generated is in an excited state.

[0247] When the excited state of the formed host material 121 is a singlet excited state, the host material 12 Singlet excitation energy is transferred from the S1 level of 1 to the S1 level of the guest material 122. As a result, the singlet excited state of the guest material 122 is formed.

[0248] Since the guest material 122 is a fluorescent material, a singlet excited state occurs in the guest material 122. Once formed, the guest material 122 rapidly emits light. For this purpose, it is preferable that the guest material 122 has a high fluorescence quantum yield. In the case of 2, the same applies when the carriers recombine and the generated excited state is a singlet excited state. It is.

[0249] Next, when the triplet excited state of the host material 121 is formed by carrier recombination, In this case, the energy levels of the host material 121 and the guest material 122 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 121 is lower than the T1 level of the guest material 122. Since this is preferable, FIG. 5C illustrates this case. may be higher than the T1 level of the guest material 122.

[0250] ·Host(121): Host material 121 ·Guest(122): Guest material 122 (fluorescent material) ·S FH : S1 level of the host material 121 T FH : T1 level of the host material 121 ·S FG : S1 level of guest material 122 (fluorescent material) T FG : T1 level of guest material 122 (fluorescent material)

[0251] As shown in Figure 5(C), triplet excitons generated by carrier recombination are close to each other. As a result, the excitation energy is transferred and the spin angular momentum is exchanged. is the S1 level of the host material 121 (S FH ) is converted into a singlet exciton with an energy of Triplet-triplet annihilation (TTA) is a reaction nihilation) occurs (see FIG. 5(C) TTA). The term excitation energy is S FH From the S1 of the guest material 122 with lower energy than that Level (S FG ) (see route E1 in Figure 5(C)), and guest material 1 A singlet excited state of 22 is formed, and the guest material 122 emits light.

[0252] 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.

[0253] In addition, when carriers recombine in the guest material 122 to form a triplet excited state, However, the triplet excited state of the guest material 122 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 122 Place(T FG ), the triplet excitation energy of guest material 122 is lower than that of guest material 1 22 T1 levels (T FG ) to the T1 level of the host material 121 (T FH ) Energy transfer (See route E2 in Figure 5(C)) and then use it for TTA.

[0254] That is, the host material 121 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 121. The singlet excitation energy is converted into singlet energy, and the singlet excitation energy is transferred to the guest material 122, thereby producing a fluorescent material. 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.

[0255] In particular, the T1 level (T FG ) is the T1 level of the host material 121 (T FH ), the weight ratio of the host material 121 to the guest material 122 is It is preferable that the weight ratio of the guest material 122 is low. The weight ratio of the guest material 122 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 122. The T1 level of the host material 121 (T FH ) to the T1 level (T FG ) to The probability of energy transfer occurring can be reduced.

[0256] The host material 121 may be composed of a single compound or a plurality of compounds. It may be formed.

[0257] In each of the above configurations, the gates used in the light-emitting units 106 and 108 The light emitting units 10 may be made of the same or different materials (fluorescent materials). When the light-emitting unit 250 has the same guest material as the light-emitting unit 108, the light-emitting unit 250 emits less current. The light-emitting element 106 and the light-emitting unit 107 are preferably light-emitting elements that exhibit high light-emitting luminance at low light-emitting values. When the light-emitting device 250 has different guest materials from the light-emitting device 108, the light-emitting device 250 exhibits multi-color emission. In particular, it is desirable to have white light with high color rendering, or at least red and green light. It is preferable to select the guest material so as to have a blue emission.

[0258] When the light-emitting unit 106 and the light-emitting unit 108 have different guest materials, The light emitted from the light-emitting layer 120 has a peak in wavelength shorter than that of the light emitted from the light-emitting layer 130. A light-emitting element using a material having a high triplet excited state is prone to luminance degradation. Therefore, by using TTA in the light-emitting layer that emits light at short wavelengths, As a result, it is possible to provide a light-emitting element with little deterioration in luminance.

[0259] <Light-emitting element configuration example 2> FIG. 6A is a schematic cross-sectional view of the light emitting element 252. FIG.

[0260] 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. The light unit 106 and the light emitting unit 110 are shown in FIG. It is preferable that the light-emitting unit 106 has a similar structure to the EL layer 100 shown in FIG. The optical units 110 may be of the same or different construction.

[0261] 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 light-emitting unit 110 may include the EL layer 10 shown in FIG. It is preferable to use 0.

[0262] The light emitting element 252 includes a light emitting layer 120 and a light emitting layer 140. In addition to the light-emitting layer 120, 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.

[0263] In addition, it is preferable that the light-emitting layer of the light-emitting unit 110 contains a phosphorescent material. The light-emitting layer 120 of the unit 106 has the structure shown in the structure example 1 of this embodiment, The light-emitting layer 140 of the light-emitting unit 110 preferably has the structure shown in the second embodiment. It is.

[0264] The emission from the light-emitting layer 120 has a 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.

[0265] In addition, by obtaining light of different emission wavelengths from the light emitting layer 120 and the light emitting layer 140, multicolor The light emitting element may have different emission peaks in the emission spectrum. Since the emitted light is composite, the emission spectrum has at least two maxima. .

[0266] The above-mentioned structure is also suitable for obtaining white light emission. By making the lights of these two colors complementary to each other, white light can be emitted.

[0267] In addition, either one or both of the light emitting layers 120 and 140 may have multiple layers with different emission wavelengths. By using a number of luminescent materials, it is possible to produce luminescent materials with high color rendering properties consisting of the three primary colors or four or more colors. White light can also be obtained. In this case, either one of the light-emitting layer 120 and the light-emitting layer 140 Alternatively, both of them may be divided into layers, and each divided layer may contain a different light-emitting material. You can do that too.

[0268] <Configuration example 3 of light-emitting element> FIG. 6B is a schematic cross-sectional view of the light emitting element 254.

[0269] The light emitting element 254 shown in FIG. 6B 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. 6B) are disposed between the electrodes 101 and 102. The light emitting unit 110 includes at least one light emitting unit 109. One of the light-emitting units has a structure similar to that of the EL layer 100 shown in FIG. The light-emitting unit preferably has a structure similar to that of the EL layer 100 shown in FIG.

[0270] In addition, in the light-emitting element 254 shown in FIG. 6B, the light-emitting unit 109 and the light-emitting unit The light-emitting unit 109 and the light-emitting unit 110 are laminated, and a charge generating layer is formed between the light-emitting unit 109 and the light-emitting unit 110. For example, the light-emitting unit 109 is provided with the EL layer 10 shown in FIG. 0, and the light-emitting unit 110 has an EL layer 100 similar to that shown in FIG. It is preferable to use the configuration.

[0271] The light emitting element 254 has a light emitting layer 130 and a light emitting layer 140. In addition to the light-emitting layer 130, the knit 109 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.

[0272] That is, the light-emitting layer 130 of the light-emitting unit 109 has the structure shown in the first embodiment. The light-emitting layer 140 of the light-emitting unit 110 has the structure shown in the second embodiment. It is preferable that:

[0273] The emission from the light-emitting layer 130 has a 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.

[0274] In addition, by obtaining light of different emission wavelengths from the light-emitting layers 130 and 140, multicolor The light emitting element may have different emission peaks in the emission spectrum. Since the emitted light is composite, the emission spectrum has at least two maxima. .

[0275] The above-mentioned structure is also suitable for obtaining white light emission. By making the lights of these two colors complementary to each other, white light can be emitted.

[0276] In addition, either one or both of the light emitting layers 130 and 140 may have multiple layers with different emission wavelengths. By using a number of luminescent materials, it is possible to produce luminescent materials with high color rendering properties consisting of the three primary colors or four or more colors. White light emission can also be obtained. In this case, either one of the light-emitting layer 130 and the light-emitting layer 140 Alternatively, both of them may be divided into layers, and each divided layer may contain a different light-emitting material. You can do that too.

[0277] <Examples of materials that can be used for the light-emitting layer> Next, materials that can be used for the light-emitting layers 120, 130, and 140 will be described. The following explains this.

[0278] <Materials that can be used for the light-emitting layer 120> In the light-emitting layer 120, the host material 121 is present in the largest amount by weight, and the guest material 122 The fluorescent material is dispersed in the host material 121. The S1 level of the host material 121 is The S1 level of the host material 121 is higher than the S1 level of the fluorescent material 122. It is preferable that the T1 level is lower than the T1 level of the photoresist material 122 (fluorescent material).

[0279] In the light-emitting layer 120, the guest material 122 is not particularly limited. The materials exemplified as the guest material 132 in the first embodiment can be used.

[0280] In addition, examples of materials that can be used as the host material 121 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: Almq3), bis(10-hydroxybenzo[h]quinolinato)beryllium(II)( Abbreviation: BeBq2), Bis(2-methyl-8-quinolinolato)(4-phenylphenolato) ) Aluminum(III) (abbreviation: BAlq), bis(8-quinolinolato)zinc(II) (abbreviation: Znq), bis[2-(2-benzoxazolyl)phenolato]zinc(II)( Abbreviation: ZnPBO), bis[2-(2-benzothiazolyl)phenolato]zinc(II)( abbreviation: ZnBTZ), and other metal complexes, 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 122 is selected. One or more types of material having gaps may be selected and used.

[0281] 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.

[0282] In the light-emitting layer 120, the host material 121 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 121 and the guest material 122 .

[0283] <Materials that can be used for the light-emitting layer 130> The light-emitting layer 130 can be made of the same material as the light-emitting layer 13 shown in the first embodiment. By using materials that can be used for 0, the generation of a singlet excited state can be achieved. A light-emitting element with high efficiency and high luminous efficiency can be manufactured.

[0284] <Materials that can be used for the light-emitting layer 140> The light-emitting layer 140 can be made of the same material as that of the light-emitting layer 14 shown in the second embodiment. By using materials that can be used for the luminescence element with low driving voltage, It is possible to create children.

[0285] In addition, the emission colors of the light-emitting materials contained in the light-emitting layers 120, 130, and 140 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 light-emitting material contained in the light-emitting layer 130 and the light-emitting layer 140 is It is preferable that the length of the axial length of the slit is shorter than that of the axial length of the slit.

[0286] In addition, the light-emitting unit 106, the light-emitting unit 108, the light-emitting unit 109, the light-emitting unit The charge generating layer 110 and the charge generating layer 115 can be formed by a deposition method (including a vacuum deposition method), an ink jet method, a coating method, etc. The layer can be formed by a method such as a cloth method or gravure printing.

[0287] The configuration described in this embodiment mode may be used in appropriate combination with the configurations described in other embodiments. There can be.

[0288] (Embodiment 4) In this embodiment mode, a light-emitting element having a different structure from those described in any of the embodiments 1 to 3 will be described. An example of this will be described below with reference to FIGS.

[0289] <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.

[0290] 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. .

[0291] 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.

[0292] 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 .

[0293] 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.

[0294] 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. When the semiconductor device has a structure in which the semiconductor device is sandwiched between conductive materials, pattern formation by an etching process becomes easy. This is preferable.

[0295] 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.

[0296] 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.

[0297] 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 that overlaps with the electrode. By providing 145, the electrodes 101 on the substrate 200 in each region are divided into islands. It becomes possible to separate.

[0298] The light-emitting layer 123B and the light-emitting layer 123G are alternately arranged in the region where they overlap with the partition wall 145. The light-emitting layer 123G and the light-emitting layer 123R may have an overlapping area. In the region where the light-emitting layer 1 overlaps the wall 145, the light-emitting layer 1 may have an overlapping region. The light-emitting layer 23R and the light-emitting layer 123B overlap each other in the region where they overlap with the partition wall 145. It may have.

[0299] 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.

[0300] 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 containing less oxygen than silicon dioxide. This refers to a film with a high nitrogen content, preferably 55 atomic % to 65 atomic % nitrogen and 100 atomic % oxygen. 1 atomic % to 20 atomic %, silicon is 25 atomic % to 35 atomic %, hydrogen is 0.1 This refers to a concentration range of more than 10 atomic % and less than 10 atomic %.

[0301] 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.

[0302] In addition, any one or more of the light-emitting layers 123B, 123G, and 123R The light-emitting layer is the light-emitting layer 130 shown in the first embodiment and the light-emitting layer 14 shown in the second embodiment. It is preferable that the compound has at least one of the above-mentioned elements. Optical elements can be fabricated.

[0303] 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.

[0304] As described above, at least one light-emitting layer is the light-emitting layer shown in the first embodiment or the second embodiment. The light emitting element 260a or the light emitting element 260b having the light emitting layer is By using the organic EL element in a pixel, a display device with high light emission efficiency can be manufactured. A display device having the element 260a or the light-emitting element 260b can reduce power consumption. Cut.

[0305] 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.

[0306] 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 any of Embodiments 1 to 3 may be referred to.

[0307] <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.

[0308] 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.

[0309] 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.

[0310] 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 charge generating layer 115 is a hole injection layer 111 and a hole transport layer 11. 2, a light-emitting layer 180, 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 .

[0311] 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.

[0312] 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 03 and the end of the electrode 104, and has an opening overlapping the electrode. By this, it is possible to separate the electrodes on the substrate 200 in each region into islands. It becomes.

[0313] 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.

[0314] 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.

[0315] 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.

[0316] 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.

[0317] 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.

[0318] 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.

[0319] 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.

[0320] In addition, the optical element 224B and the optical element 224G are arranged in a region overlapping with the light-shielding layer 223. Alternatively, the optical element 224G and the optical element 224G may have an overlapping area. 24R may have an overlapping area with the light-shielding layer 223. Alternatively, the optical element 224R and the optical element 224B are arranged in an area overlapping the light-shielding layer 223. In this case, the two portions may have overlapping regions.

[0321] In addition, the substrate 200 and the substrate 220 having the optical element are the same as those in the first embodiment. That's good.

[0322] Furthermore, the light emitting element 262a and the light emitting element 262b have a microcavity structure. .

[0323] <Microcavity structure> The light emitted from the light emitting layer 170 and the light emitting layer 180 is incident on a pair of electrodes (for example, the electrode 10 The light emitting layer 170 and the light emitting layer 180 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 180 can be intensified. and the optical distance from the reflective area of ​​the electrode 102 to the luminous area of ​​the luminous layer 180. By adjusting the optical path, the light emitted from the light-emitting layer 180 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 180 are laminated, the optical distances of the light emitting layer 170 and the light emitting layer 180 are It is preferable to optimize the spacing.

[0324] 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 180 can be enhanced at a desired wavelength. At least one of the thicknesses of the hole injection layer 111 and the hole transport layer 112 is made different in the region. This may enhance the light emitted from light-emitting layer 170 and light-emitting layer 180.

[0325] 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 180, 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).

[0326] 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 180 may be derived. In the case where it is difficult to precisely determine the light-emitting regions of the light-emitting layer 170 and the light-emitting layer 180, By assuming that any region of the light emitting layer 180 is a light emitting region, the light emitting layer 170 and the light emitting layer 180 An optical path that enhances the light emitted from the

[0327] 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. In the above structure, the conductive layer 101b and the conductive layer 103 It is preferable that the conductive layer 104b has a function of transmitting light. The materials constituting the conductive layers 103b, 104b may be the same as each other. The conductive layers 101b, 103b, and 104b may be made of the same material. In the case of using a material, it is preferable because pattern formation by an etching process becomes easy. Each of the conductive layers 101b, 103b, and 104b is formed by stacking two or more layers. The above configuration may also be used.

[0328] Since the light emitting element 262a shown in FIG. 8A is a top emission type light emitting element, the conductive layer It is preferable that the conductive layer 101a, the conductive layer 103a, and the conductive layer 104a have a function of reflecting light. In addition, the electrode 102 preferably has both a light transmitting function and a light reflecting function. preferable.

[0329] 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.

[0330] 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.

[0331] In addition, the light-emitting layers 170 and 180 in the light-emitting elements 262a and 262b At least one of the above preferably has the configuration shown in the first or second embodiment. In this way, a light-emitting element exhibiting high luminous efficiency can be manufactured.

[0332] The light-emitting layer 170 and the light-emitting layer 180 are, for example, the light-emitting layer 180a and the light-emitting layer 180b. In this way, one or both of the light-emitting layers may have a structure in which two layers are laminated. Two types of luminescent materials, a luminescent material and a second luminescent material, which have the function of exhibiting different colors, are used. By using each of them, it is possible to obtain light emission including a plurality of colors. The luminescent material used for each luminescent layer is selected so that the luminescent layer 180 emits white light. It is preferable to select

[0333] In addition, the light-emitting layer 170 or the light-emitting layer 180 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.

[0334] 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.

[0335] Regarding other configurations of the light emitting element 262a and the light emitting element 262b, 260a or the light-emitting element 260b, or the light-emitting element shown in any one of the first to third embodiments. The configuration of the element should be taken into consideration.

[0336] <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.

[0337] 9 and 10 are cross-sectional views illustrating a method for manufacturing a light-emitting element of one embodiment of the present invention. do.

[0338] The method for fabricating the light emitting element 262a described below includes seven steps, namely, steps 1 to 7. do.

[0339] <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)).

[0340] 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.

[0341] 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.

[0342] <<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. 9B).

[0343] 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.

[0344] 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.

[0345] <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).

[0346] 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.

[0347] 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 processed into islands to form electrodes 101, 103, and 104. Form 4.

[0348] <Fourth step> The fourth step is to deposit the hole injection layer 111, the hole transport layer 112, the light emitting layer 180, the electron transport layer 113, an electron injection layer 114, and a charge generation layer 115 are formed (FIG. 10(A) reference).

[0349] 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.

[0350] The light-emitting layer 180 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 any of the embodiments 1 to 3 can be used. It is preferable that the light-emitting layer 180 is made of two layers. The two light-emitting layers preferably contain light-emitting materials that emit light of different colors. .

[0351] 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.

[0352] 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.

[0353] <<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). .

[0354] 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.

[0355] 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: As the guest material, a fluorescent organic compound can be used. The fluorescent organic compound may be evaporated alone, or may be evaporated in a mixture with other materials. In addition, a fluorescent organic compound is used as a guest material, and the excitation energy is higher than that of the guest material. The guest material may be dispersed in a larger host material and then vapor-deposited.

[0356] 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.

[0357] 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.

[0358] 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.

[0359] <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)).

[0360] 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.

[0361] <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 220. The light-shielding layer 223, the optical element 224B, the optical element 224G, and the optical element 224R are bonded together. This is the process of aligning the components and sealing them with a sealant (not shown).

[0362] Through the above steps, the light-emitting element 262a shown in FIG. 8(A) can be formed.

[0363] Note that the structure described in this embodiment mode may be used in appropriate combination with structures described in other embodiments. There can be.

[0364] (Embodiment 5) In this embodiment, a display device according to one embodiment of the present invention will be described with reference to FIGS. Reveal.

[0365] <Display device configuration example 1> FIG. 11A is a top view showing a display device 600, and FIG. 11B is a diagram showing the display device 600 shown in FIG. The display device 600 includes a driving circuit section ( The display device includes a signal line driver circuit portion 601, a scanning line driver circuit portion 603, and a pixel portion 602. The signal line driver circuit section 601, the scanning line driver circuit section 603, and the pixel section 602 are It has the function of controlling the light emission of the element.

[0366] The display device 600 includes an element substrate 610, a sealing substrate 604, a sealant 605, The semiconductor device has an area 607 surrounded by a sealing material 605, wiring 608, and an FPC 609. do.

[0367] The lead wiring 608 is connected to the signal line driver circuit portion 601 and the scanning line driver circuit portion 603. This is the wiring for transmitting the input signal. It is connected to the external input terminal FPC609 and It receives the FP signal, clock signal, start signal, reset signal, etc. Although only C609 is shown, FPC609 has a printed wiring board (PWB: Pri A standard Wiring Board may be installed.

[0368] The signal line driver circuit portion 601 includes an N-channel transistor 623 and a P-channel A CMOS circuit is formed by combining this transistor 624. The path section 601 or the scanning line driver circuit section 603 may be implemented by various CMOS circuits, PMOS circuits, or In this embodiment, the driving circuit section is formed on the substrate. Although the display device shown has the driver and pixels formed on the same surface, this is not necessarily the case. Alternatively, the driving circuitry may be formed externally rather than on the substrate.

[0369] The pixel portion 602 includes a switching transistor 611 and a current control transistor 612. A lower part electrically connected to the drain of the transistor 612 for current control A partition wall 614 is formed to cover an end of the lower electrode 613. The partition wall 614 can be made of a positive photosensitive acrylic resin film.

[0370] In order to improve the covering property, the partition wall 614 is provided with a curved surface having a curvature at the upper end or the lower end. For example, a positive photosensitive acrylic is used as the material for the partition wall 614. In this case, only the upper end of the partition wall 614 is curved with a radius of curvature (0.2 μm or more and 3 μm or less). It is preferable that the partition wall 614 is made of a negative photosensitive resin or a polyimide. Any of the above-mentioned photosensitive resins can be used.

[0371] The structure of the transistors (transistors 611, 612, 623, and 624) is For example, a staggered transistor may be used. There is no particular limitation on the polarity, and it has N-channel and P-channel transistors. The structure is such that the transistors are either N-channel or P-channel. A structure consisting of only one of the two may be used. For example, an amorphous semiconductor film or a crystalline semiconductor film may be used. Semiconductor materials include group 14 (silicon, etc.) semiconductors, compound semiconductors (oxide As the transistor, for example, The energy gap is 2 eV or more, preferably 2.5 eV or more, and more preferably 3 eV or more. By using the oxide semiconductor, the off-state current of a transistor can be reduced. As the oxide semiconductor, In-Ga oxide, In-M-Zn oxide (M is , Aluminum (Al), Gallium (Ga), Yttrium (Y), Zirconium (Zr ), lanthanum (La), cerium (Ce), tin (Sn), hafnium (Hf), or neodymium (Nb). Examples include Nd (Nd).

[0372] An EL layer 616 and an upper electrode 617 are formed on the lower electrode 613. The lower electrode 613 functions as an anode, and the upper electrode 617 functions as a cathode. do.

[0373] The EL layer 616 is formed by deposition using a deposition mask, inkjet printing, spin coating, etc. The EL layer 616 can be formed by various methods such as a low-temperature method. The compound may be a molecular compound or a polymer compound (including an oligomer or a dendrimer).

[0374] The lower electrode 613, the EL layer 616, and the upper electrode 617 constitute a light-emitting element 618. The light emitting element 618 has the structure of any one of the first to third embodiments. In addition, in the case where a plurality of light-emitting elements are formed in a pixel portion, The light-emitting element according to the third embodiment and the light-emitting element having other structures are both included. That's fine.

[0375] In addition, the sealing substrate 604 is bonded to the element substrate 610 with the sealant 605, A light-emitting element is disposed in an area 607 surrounded by an element substrate 610, a sealing substrate 604, and a sealant 605. The region 607 is filled with a filler. In addition to being filled with an inert gas (nitrogen, argon, etc.), it can also be used as a sealant 605. They may also be filled with UV-curable or heat-curable resins, e.g. PVC ( Polyvinyl chloride) resin, acrylic resin, polyimide resin, epoxy resin, Silicone resin, PVB (polyvinyl butyral) resin, or EVA (ethylene vinyl acetate) A recess is formed in the sealing substrate, and a desiccant is placed therein. By providing this, deterioration due to the influence of moisture can be suppressed, and this is a preferable configuration.

[0376] In addition, the optical element 621 is disposed below the sealing substrate 604 so as to overlap the light emitting element 618. In addition, a light-shielding layer 622 is provided below the sealing substrate 604. The optical element and the light-shielding layer 621 and the light-shielding layer 622 are respectively the optical element and the light-shielding layer shown in the third embodiment. The same configuration may be used.

[0377] It is preferable to use epoxy resin or glass frit for the sealing material 605. In addition, it is desirable that these materials are as impermeable to moisture and oxygen as possible. In addition, the material used for the sealing substrate 604 may be a glass substrate, a quartz substrate, or FRP (Fiber Reinforced Plastics). Reinforced Plastics), PVF (Polyvinyl Fluoride), Poly A plastic substrate made of ester, acrylic or the like can be used.

[0378] As described above, the light emitting element and the optical element described in any of the first to third embodiments are provided. It is possible to obtain a display device that

[0379] <Display device configuration example 2> Next, another example of the display device will be described with reference to FIGS. 12(A)(B) and 13. 12A, 12B, and 13 are cross-sectional views of a display device according to one embodiment of the present invention. .

[0380] FIG. 12A shows a substrate 1001, an insulating base film 1002, a gate insulating film 1003, and a gate Electrodes 1006, 1007, 1008, a first interlayer insulating film 1020, a second interlayer insulating film 10 21, peripheral portion 1042, pixel portion 1040, driving circuit portion 1041, lower electrode 10 of light emitting element 24R, 1024G, 1024B, partition wall 1025, EL layer 1028, upper electrode of light emitting element 1026, a sealing layer 1029, a sealing substrate 1031, a seal material 1032, etc. are illustrated. .

[0381] In addition, in FIG. 12A, as an example of an optical element, a colored layer (a red colored layer 1034R, A green colored layer 1034G and a blue colored layer 1034B are provided on a transparent substrate 1033. A light-shielding layer 1035 may be further provided. The base material 1033 is aligned and fixed to the substrate 1001. is covered with an overcoat layer 1036. In FIG. Since the light that passes through it is red, green, and blue, images can be displayed using three color pixels.

[0382] In FIG. 12B, as an example of an optical element, a colored layer (a red colored layer 1034R, a green colored layer The colored layer 1034G and the blue colored layer 1034B are formed between the gate insulating film 1003 and the first interlayer insulating film. In this example, the colored layer is formed between the substrate 1001 and the film 1020. It may be provided between the substrates 1031 .

[0383] In FIG. 13, colored layers (a red colored layer 1034R, a green colored layer 1034G, blue colored layer 1034B) are formed between the first interlayer insulating film 1020 and the second interlayer insulating film In this example, the colored layer is formed between the substrate 1001 and the sealing substrate 1021. It may be provided between the plates 1031.

[0384] In the display device described above, the side of the substrate 1001 on which the transistors are formed is The display device has a bottom emission structure for extracting light. The display device may also have a structure for extracting emitted light (top emission type).

[0385] <Display device configuration example 3> An example of a cross-sectional view of a top-emission type display device is shown in FIG. 14(A) and (B). 12(A) and 12(B) are cross-sectional views illustrating a display device of one embodiment of the present invention. 13.) and the driving circuit section 1041, the peripheral section 1042, etc. shown in FIG.

[0386] In this case, the substrate 1001 can be a substrate that does not transmit light. A bottom emission type display device is manufactured until the connection electrode for connecting the anode of the optical element is fabricated. Thereafter, a third interlayer insulating film 1037 is formed so as to cover the electrode 1022. This insulating film may also play a role in planarization. The third interlayer insulating film 1037 is the first In addition to the same material as the interlayer insulating film 2, various other materials can be used.

[0387] The lower electrodes 1024R, 1024G, and 1024B of the light-emitting element are anodes here, but Also, top emission type displays as shown in Figure 14(A)(B) may be used. In the case of a photodiode device, the lower electrodes 1024R, 1024G, and 1024B have a function of reflecting light. In addition, an upper electrode 1026 is provided on the EL layer 1028. The electrode 1026 has a function of reflecting light and a function of transmitting light. A microcavity structure is adopted between 24G, 1024B and the upper electrode 1026, It is desirable to increase the light intensity at a particular wavelength.

[0388] In the top emission structure shown in FIG. 14(A), the colored layer (red colored layer 1034 R, a green colored layer 1034G, and a blue colored layer 1034B) are provided on the sealing substrate 1031 The sealing substrate 1031 has a shielding layer between the pixels. An optical layer 1035 may be provided. Note that the sealing substrate 1031 may be a light-transmitting substrate. This is preferable.

[0389] In addition, in FIG. 14A, a plurality of light emitting elements and the plurality of light emitting elements are colored. Although the configuration in which a layer is provided is illustrated, the present invention is not limited to this. For example, as shown in FIG. In the embodiment, the green color layer is not provided, and a red color layer 1034R and a blue color layer 1034B are provided. It is also possible to use three colors, red, green, and blue, for full color display. In this way, when a colored layer is provided on each light-emitting element, it is possible to suppress reflection of external light. On the other hand, as shown in FIG. 14(B), a red colored layer is not provided. In the case where a colored layer of a green color and a colored layer of a blue color are provided, light emitted from a green light emitting element is Since the energy loss is small, the power consumption can be reduced.

[0390] <Display device configuration example 4> The display device described above has a configuration having three sub-pixels of three colors (red, green, and blue). A structure with four sub-pixels of four colors (red, green, blue, yellow, or red, green, blue, white) 15 to 17 show the lower electrodes 1024R, 1024G, 1024B, 15(A)(B) and 16 show the configuration of a display device having a 1024Y and 1024Y. A structure in which light is extracted from the substrate 1001 side on which the transistor is formed (bottom emission type). 17(A) and (B) show a structure in which light is extracted to the sealing substrate 1031 side ( It is a top-emission type display device.

[0391] FIG. 15(A) shows an optical element (colored layer 1034R, colored layer 1034G, colored layer 1034B 15 is an example of a display device in which a colored layer 1034Y is provided on a transparent substrate 1033. (B) shows the optical element (colored layer 1034R, colored layer 1034G, colored layer 1034B, colored layer 1034Y) is formed between the gate insulating film 1003 and the first interlayer insulating film 1020. FIG. 16 shows an example of an optical element (colored layer 1034R, colored layer 1034G, The color layer 1034B and the color layer 1034Y are disposed between the first interlayer insulating film 1020 and the second interlayer insulating film 1021. 021 is an example of a display device formed between the

[0392] The colored layer 1034R transmits red light, the colored layer 1034G transmits green light, and the colored layer The colored layer 1034B has a function of transmitting blue light. The colored layer 1034Y has a function of transmitting yellow light. or the ability to transmit multiple light beams selected from blue, green, yellow, and red. The colored layer 1034Y transmits a plurality of lights selected from blue, green, yellow, and red. When the colored layer 1034Y has a function of transmitting light, the light transmitted through the colored layer 1034Y may be white. Since the light emitting element that emits white light has high luminous efficiency, the display having the colored layer 1034Y is preferably used. The device can reduce power consumption.

[0393] In the top emission type display device shown in FIG. In the light-emitting element having the lower electrode 1024R, Between 1024G, 1024B, 1024Y and the upper electrode 1026, a microcavity In the display device of FIG. 17(A), a colored layer (a red color Color layer 1034R, green color layer 1034G, blue color layer 1034B, and yellow color layer Sealing can be performed by a sealing substrate 1031 provided with a sealing layer 1034Y).

[0394] The light emitted through the microcavity and the yellow colored layer 1034Y is in the yellow region. The emission spectrum is in the yellow region. Yellow is a color with high visibility, so yellow emission is The light-emitting element exhibiting this has high light-emitting efficiency. , power consumption can be reduced.

[0395] In addition, in FIG. 17(A), a plurality of light emitting elements and the plurality of light emitting elements are colored. Although the configuration in which a layer is provided is illustrated, the present invention is not limited to this. For example, as shown in FIG. 1034A, the yellow color layer is not provided, and the red color layer 1034R, the green color layer 1034G, and the blue color layer 1034R are provided. By providing a colored layer 1034B, four colors of red, green, blue, and yellow, or four colors of red, green, blue, and white can be used. As shown in FIG. 17(A), a light-emitting element and the light-emitting element When a colored layer is provided on each optical element, it is possible to suppress the reflection of external light. On the other hand, as shown in FIG. 17B, a light emitting element and a yellow coloring layer are not provided, and a red coloring layer is not provided. When a colored layer of a color, a green colored layer, and a blue colored layer are provided, the color of the light is yellow or white. Since the energy loss of the light emitted from the light-emitting element is small, power consumption can be reduced. This has a positive effect.

[0396] <Display device configuration example 5> Next, a display device according to another embodiment of the present invention is shown in FIG. 18 is a cross-sectional view taken along dashed lines AB and CD. In FIG. 11B, the same reference numerals are used for parts having the same functions as those in FIG. Detailed explanation will be omitted.

[0397] The display device 600 shown in FIG. 18 includes an element substrate 610, a sealing substrate 604, and a sealant 60 The region 607 surrounded by 5 has sealing layers 607a, 607b, and 607c. For example, one or more of the sealing layers 607a, 607b, and 607c may include For example, PVC (polyvinyl chloride) resin, acrylic resin, polyimide resin, etc. epoxy resin, silicone resin, PVB (polyvinyl butyral) resin, or EVA Resins such as ethylene vinyl acetate resins can be used. Silicon oxide nitride, silicon nitride oxide, silicon nitride, aluminum oxide, aluminum nitride Alternatively, an inorganic material such as aluminum may be used. By forming the layer c, deterioration of the light emitting element 618 due to impurities such as water can be suppressed. It is preferable to form the sealing layers 607a, 607b, and 607c. The cooling material 605 does not need to be provided.

[0398] In addition, the sealing layer 607a, the sealing layer 607b, and the sealing layer 607c are any one or two. Alternatively, four or more sealing layers may be formed. Impurities such as the above may penetrate from the outside of the display device 600 to the light emitting element 618 inside the display device. In addition, when the sealing layer is multi-layered, the sealing layer may be made of a resin and an inorganic material. It is preferable to laminate the material.

[0399] <Display device configuration example 6> The display devices shown in the configuration examples 1 to 4 in this embodiment have optical elements. However, in one embodiment of the present invention, an optical element does not necessarily have to be provided.

[0400] The display device shown in FIG. 19(A)(B) has a structure in which light is extracted to the sealing substrate 1031 side (transistor). FIG. 19(A) shows a light-emitting layer 1028R and a light-emitting layer 1028R. FIG. 19B shows an example of a display device having a light-emitting layer 1028G and a light-emitting layer 1028B. A surface having an optical layer 1028R, a light-emitting layer 1028G, a light-emitting layer 1028B, and a light-emitting layer 1028Y. This is an example of a display device.

[0401] The light-emitting layer 1028R emits red light, the light-emitting layer 1028G emits green light, and The light emitting layer 1028B has a function of emitting blue light. or a function of exhibiting multiple luminescence selected from blue, green, and red. The light emitted by the light-emitting layer 1028Y may be white. Since the light-emitting element that emits light has high light-emitting efficiency, the display device having the light-emitting layer 1028Y has a high light-emitting efficiency. Power consumption can be reduced.

[0402] The display devices shown in FIG. 19(A) and FIG. 19(B) each have an EL layer that emits light of different colors. Since the pixel has the colored layer, it is not necessary to provide a colored layer that serves as an optical element.

[0403] The sealing layer 1029 is made of, for example, a PVC (polyvinyl chloride) resin or an acrylic resin. Resin, polyimide resin, epoxy resin, silicone resin, PVB (polyvinyl chloride) Resins such as ethylene vinyl acetate (EVA) resins are used. In addition, silicon oxide, silicon oxynitride, silicon nitride oxide, and silicon nitride can be used. Alternatively, an inorganic material such as aluminum oxide or aluminum nitride may be used. By forming the insulating layer, deterioration of the light-emitting element due to impurities such as water can be suppressed, which is preferable.

[0404] In addition, the sealing layer 1029 may be any one or two, or may be four or more sealing layers. By forming the sealing layer in multiple layers, impurities such as water can be prevented from entering the display device from the outside. This is preferable because it can effectively prevent the infiltration of the ultraviolet ray from the sealing layer into the inside of the display device. In the case of a multi-layer structure, a preferable configuration is one in which a resin and an inorganic material are laminated.

[0405] The sealing substrate 1031 only needs to have a function of protecting the light-emitting element. Therefore, the sealing substrate 1031 can be a flexible substrate or film.

[0406] Note that the configuration shown in this embodiment may be appropriately combined with other embodiments or other configurations in this embodiment. Combinations are possible.

[0407] (Embodiment 6) In this embodiment, a display device including a light-emitting element of one embodiment of the present invention will be described with reference to FIGS. The explanation will be given with reference to FIG.

[0408] Note that FIG. 20A is a block diagram illustrating a display device of one embodiment of the present invention. 1B is a circuit diagram illustrating a pixel circuit included in a display device of one embodiment of the present invention.

[0409] <Explanation about the display device> The display device shown in FIG. 20A has a region having pixels of a display element (hereinafter, referred to as a pixel portion 802). ) and a circuit section ( hereinafter referred to as a drive circuit section 804) and a circuit having a function of protecting the element (hereinafter referred to as a protection circuit 80 6) and a terminal portion 807. Note that the protection circuit 806 is not provided. This is also fine.

[0410] A part or the whole of the driver circuit portion 804 is formed on the same substrate as the pixel portion 802. This makes it possible to reduce the number of parts and terminals. When a part or the whole of the pixel portion 802 is not formed on the same substrate, the driving circuit A part or the whole of the path portion 804 is COG or TAB (Tape Automated Band). It can be implemented by using the onding.

[0411] The pixel section 802 is arranged in X rows (X is a natural number of 2 or more) and Y columns (Y is a natural number of 2 or more). A circuit for driving a plurality of display elements (hereinafter referred to as pixel circuit 801) is provided. The path portion 804 is a circuit that outputs a signal (scanning signal) for selecting a pixel (hereinafter, a scanning line driving circuit 804a) to supply signals (data signals) for driving the display elements of the pixels. The image display device 804 includes driver circuits such as a circuit (hereinafter, a signal line driver circuit 804b).

[0412] The scanning line driver circuit 804a includes a shift register and the like. A signal for driving the shift register is input via a terminal portion 807, and a signal is output. For example, a start pulse signal, a clock signal, etc. are input to the scanning line driver circuit 804a. The scanning line driver circuit 804a outputs a pulse signal. The scanning lines GL_1 to GL_X are connected to the ground. A plurality of driving circuits 804a are provided, and the scanning lines GL_1 to Alternatively, the scanning line driving circuit 804a may control the GL_X by dividing it. However, the present invention is not limited to this, and the scanning line driving circuit 80 4a may also provide another signal.

[0413] The signal line driver circuit 804b includes a shift register and the like. Through the terminal portion 807, a signal for driving the shift register and a source of a data signal are input. The signal line driver circuit 804b drives the pixel circuit based on the image signal. The signal line driver circuit 804b has a function of generating a data signal to be written to the signal line driver circuit 801. A data signal is generated according to a pulse signal obtained by inputting a start pulse, a clock signal, etc. The signal line driver circuit 804b has a function of controlling the output of a data signal. The data lines DL_1 to DL_Y are connected to the data line 101 through the data line 102. Alternatively, the signal line driver circuit 804b may have a function of supplying an initialization signal. However, the present invention is not limited to this, and the signal line driver circuit 804b may also supply other signals. It is possible.

[0414] The signal line driver circuit 804b is configured using, for example, a plurality of analog switches. The signal line driver circuit 804b sequentially turns on a plurality of analog switches, The image signal can be time-division-multiplexed and output as a data signal. Also, a shift register, etc. The signal line driver circuit 804b may be formed using the same.

[0415] Each of the plurality of pixel circuits 801 is connected to one of the plurality of scanning lines GL to which a scanning signal is applied. A pulse signal is inputted through the data line DL, and a data signal is given through one of the data lines DL. A data signal is input to each of the pixel circuits 801 via a scanning line driving circuit. 804a controls writing and holding of data of the data signal. For example, The second pixel circuit 801 is connected to a scanning line drive circuit via a scanning line GL_m (m is a natural number equal to or smaller than X). A pulse signal is input from 804a, and the potential of the data line DL_n ( A data signal is input from the signal line driver circuit 804b via a data line driver 804c (n is a natural number equal to or smaller than Y).

[0416] The protection circuit 806 shown in FIG. 20A is, for example, a scanning line driver circuit 804a and a pixel circuit 8 01. Alternatively, the protection circuit 806 is connected to the scanning line GL, which is the wiring between the signal line driver The data line DL is connected between the circuit 804b and the pixel circuit 801. The protection circuit 806 can be connected to a wiring between the scanning line driver circuit 804a and the terminal portion 807. Alternatively, the protection circuit 806 may be a wiring between the signal line driver circuit 804b and the terminal portion 807. The terminal portion 807 can be connected to a power supply and a line from an external circuit to the display device. This refers to the part provided with terminals for inputting control signals and image signals.

[0417] When a potential outside a certain range is applied to the wiring to which the protection circuit 806 is connected, the protection circuit This is a circuit that brings one wire into electrical continuity with another wire.

[0418] As shown in FIG. 20A, a pixel section 802 and a driver circuit section 804 are provided with a protection circuit 80. 6, ESD (Electro Static Discharge: This can improve the resistance of the display device to overcurrent caused by electrostatic discharge (ESD) and the like. However, the configuration of the protection circuit 806 is not limited to this. For example, A configuration in which a protection circuit 806 is connected, or a protection circuit 806 is connected to a signal line driver circuit 804b Alternatively, a protection circuit 806 may be connected to the terminal portion 807. It can also be done like this.

[0419] In FIG. 20A, the scanning line driver circuit 804a and the signal line driver circuit 804b Therefore, although an example in which the driver circuit portion 804 is formed is shown, the present invention is not limited to this configuration. For example, only the scanning line driver circuit 804a is formed, and a signal line driver circuit is separately formed. A substrate (for example, a drive circuit substrate formed of a single crystal semiconductor film or a polycrystalline semiconductor film) is mounted. It may also be configured as follows.

[0420] <Pixel circuit configuration example> The pixel circuits 801 shown in FIG. 20A may have a configuration shown in FIG. 20B. It is possible.

[0421] The pixel circuit 801 shown in FIG. 20B includes transistors 852 and 854 and a capacitor 86. 2 and a light-emitting element 872.

[0422] A data signal is applied to one of the source and drain electrodes of the transistor 852. The gate of the transistor 852 is electrically connected to the wiring (data line DL_n). The electrode is electrically connected to a wiring (scanning line GL_m) to which a gate signal is applied.

[0423] The transistor 852 has a function of controlling writing of data signals.

[0424] One of a pair of electrodes of the capacitor 862 is connected to a wiring to which a potential is applied (hereinafter, a potential supply line VL _a), and the other is electrically connected to the source electrode and drain electrode of the transistor 852. The second electrode is electrically connected to the other of the first and second electrodes.

[0425] The capacitor 862 functions as a storage capacitor for storing written data.

[0426] One of the source electrode and the drain electrode of the transistor 854 is connected to the potential supply line VL_a. In addition, the gate electrode of the transistor 854 is electrically connected to the It is electrically connected to the other of the source electrode and the drain electrode.

[0427] One of the anode and the cathode of the light-emitting element 872 is electrically connected to the potential supply line VL_b. The other one is electrically connected to the other of the source electrode and the drain electrode of the transistor 854. will be done.

[0428] The light-emitting element 872 may be any of the light-emitting elements described in any of the embodiments 1 to 3. can be done.

[0429] A high power supply potential VDD is applied to one of the potential supply lines VL_a and VL_b. and the other is supplied with a low power supply potential VSS.

[0430] In a display device having the pixel circuit 801 shown in FIG. 20B, for example, The pixel circuits 801 in each row are selected in sequence by the scanning line driving circuit 804a, and the transistors 852 are turned on. The data signal is written by turning it on.

[0431] In the pixel circuit 801 to which the data has been written, the transistor 852 is turned off. Furthermore, the transistor 854 is in a holding state in response to the potential of the written data signal. The amount of current flowing between the source electrode and the drain electrode is controlled, and the light emitting element 872 The light is emitted with a brightness that corresponds to the flow rate. By performing this process row by row, an image can be displayed.

[0432] In addition, the pixel circuit has a function to correct the effects of fluctuations in the threshold voltage of transistors, etc. 21(A)(B) and 22(A)(B) show an example of a pixel circuit.

[0433] The pixel circuit shown in FIG. 21A includes six transistors (transistors 303_1 to 303_3). 303_6), a capacitor 304, and a light-emitting element 305. In the pixel circuit shown in FIG. The transistors 303_1 to 303_6 are electrically connected to each other. For example, a P-channel transistor can be used.

[0434] The pixel circuit shown in FIG. 21B is the pixel circuit shown in FIG. 21A, except that a transistor 303 is added. In addition, the pixel circuit shown in FIG. 21B includes a wiring 301_6 and The wiring 301_5 and the wiring 301_6 are electrically connected to each other. may be electrically connected to each other. For example, a P-channel transistor can be used.

[0435] The pixel circuit shown in FIG. 22A includes six transistors (transistors 308_1 to 308_3). 08_6), a capacitor 304, and a light-emitting element 305. The pixel circuit shown in FIG. Here, the wiring 306_1 and the wiring 306_3 are electrically connected to each other. The transistors 308_1 to 308_6 may be electrically connected to each other. For example, a P-channel transistor can be used.

[0436] The pixel circuit shown in FIG. 22B includes two transistors (transistor 309_1 and transistor transistor 309_2) and two capacitive elements (capacitive element 304_1 and capacitive element 304_ 2) and a light-emitting element 305. In addition, the pixel circuit shown in FIG. 11_1 to 311_3, the wiring 312_1, and the wiring 312_2 are electrically connected to each other. In addition, by configuring the pixel circuit as shown in FIG. 22(B), for example, The transistor 309 can be a current-driven type (also called a CVCC type). For example, a P-channel transistor can be used for 1 and 309_2. .

[0437] In addition, the light-emitting element of one embodiment of the present invention may be an active master having an active element in a pixel of a display device. A display device that uses a trix method or a passive matrix method that does not have active elements in the pixels of the display device. It can be applied to each method.

[0438] In the active matrix method, a transistor is used as an active element (active element, nonlinear element). By using not only transistors but also various active elements (active elements, nonlinear elements), For example, MIM (Metal Insulator Metal) or T It is also possible to use FD (Thin Film Diode) and other elements. Since the number of manufacturing steps is small, it is possible to reduce manufacturing costs and improve yields. Alternatively, these elements can improve the aperture ratio due to their small size. This makes it possible to achieve low power consumption and high brightness.

[0439] As a non-active matrix type, active elements (active elements, nonlinear elements It is also possible to use a passive matrix type that does not use active elements. Since it does not use any nonlinear elements, there are fewer manufacturing steps, which reduces manufacturing costs and improves yield. It is possible to improve the accuracy. Or, it is possible to use active elements (active elements, nonlinear elements) Since the aperture ratio is not increased, it is possible to achieve low power consumption and high brightness. It is possible to do this.

[0440] The structure described in this embodiment may be used in appropriate combination with structures described in other embodiments. can be done.

[0441] (Embodiment 7) In this embodiment, a display device including a light-emitting element of one embodiment of the present invention and a display device An electronic device having an input device attached thereto will be described with reference to FIGS. 23 to 27. FIG.

[0442] <Touch panel explanation 1> In the present embodiment, an electronic device that combines a display device and an input device is used as an example of the electronic device. A touch panel 2000 having the touch sensor 2000 will be described. The case where the .lambda.

[0443] 23(A) and (B) are perspective views of the touch panel 2000. In B), representative components of touch panel 2000 are shown for clarity.

[0444] The touch panel 2000 includes a display device 2501 and a touch sensor 2595 (see FIG. 2). 3(B)). The touch panel 2000 includes a substrate 2510, a substrate 2570, and a substrate The substrate 2510, the substrate 2570, and the substrate 2590 are all However, any one of the substrates 2510, 2570, and 2590 may be flexible. Alternatively, one or all of the components may be configured to be inflexible.

[0445] The display device 2501 includes a plurality of pixels on a substrate 2510 and a display device that can supply signals to the pixels. The plurality of wirings 2511 are arranged around the periphery of the substrate 2510. The wire is routed through a wire loop, part of which constitutes the terminal 2519. The terminal 2519 is an FPC 2509 (1). In addition, the plurality of wirings 2511 are electrically connected to the signal line driver circuit 2503s ( The signal from 1) can be fed to multiple pixels.

[0446] The substrate 2590 is electrically connected to the touch sensor 2595. The plurality of wirings 2598 are routed around the periphery of the substrate 2590. A part of the terminal is electrically connected to the FPC2509(2). In FIG. 23B, for clarity, the back side of the substrate 2590 (substrate 2510) is shown. The electrodes and wiring of the touch sensor 2595 provided on the surface opposite to the touch panel 2591 are shown by solid lines. .

[0447] As the touch sensor 2595, for example, a capacitive touch sensor can be used. The capacitive type includes a surface type capacitive type and a projected type capacitive type.

[0448] The projected capacitive type is classified into self-capacitance type, mutual capacitance type, etc., mainly based on the difference in the driving method. The mutual capacitance method is preferable because it enables simultaneous multi-point detection.

[0449] The touch sensor 2595 shown in FIG. 23(B) is a projected capacitive touch sensor. This is a configuration in which the .

[0450] The touch sensor 2595 can detect the proximity or contact of a detection target such as a finger. Various sensors can be applied.

[0451] The projected capacitive touch sensor 2595 has an electrode 2591 and an electrode 2592. The electrode 2591 is electrically connected to one of a plurality of wirings 2598, and the electrode 2592 is It is electrically connected to any other of the multiple wirings 2598.

[0452] As shown in FIG. 23(A) and (B), the electrodes 2592 are arranged in a single direction. The shape is such that the four quadrilaterals are connected at their corners.

[0453] The electrode 2591 is quadrilateral and is repeated in a direction intersecting the direction in which the electrode 2592 extends. are placed.

[0454] The wiring 2594 is electrically connected to the two electrodes 2591 that sandwich the electrode 2592. In this case, it is preferable that the area of ​​the intersection between the electrode 2592 and the wiring 2594 is as small as possible. This reduces the area of ​​the region where no electrodes are provided, reducing variations in transmittance. As a result, the variation in the brightness of the light passing through the touch sensor 2595 can be reduced. can be done.

[0455] The shapes of the electrodes 2591 and 2592 are not limited to this, and may take various shapes. For example, multiple electrodes 2591 are arranged with as few gaps as possible, and are A plurality of electrodes 2592 are provided at intervals so that there is an area where the electrodes 2592 do not overlap with the electrodes 2591. In this case, a wire may be provided between two adjacent electrodes 2592, which is electrically isolated from the two adjacent electrodes 2592. Providing an insulated dummy electrode is preferable because it can reduce the area of ​​the region with different transmittance. .

[0456] <Explanation about the display device> Next, the display device 2501 will be described in detail with reference to FIG. ) corresponds to a cross-sectional view taken along dashed line X1-X2 shown in FIG. 23(B).

[0457] The display device 2501 has a plurality of pixels arranged in a matrix. The display device has a display element and a pixel circuit for driving the display element.

[0458] In the following description, a light emitting element that emits white light is used as a display element. However, the display element is not limited to this. For example, Light emitting elements with different luminous colors may be applied so that the colors are different.

[0459] The substrate 2510 and the substrate 2570 may have a water vapor permeability of, for example, 1×10 -5 g· m -2 ·day -1 Less than or equal to 1×10 -6 g m -2 ·day -1 Possible A flexible material can be preferably used. It is preferable to use a material having a coefficient of thermal expansion approximately equal to that of the plate 2570. For example, is 1×10 -3 / K or less, preferably 5×10 -5 / K or less, preferably 1×10 - 5 A material having a viscosity of 0.1 to 1.0 μm may be preferably used.

[0460] The substrate 2510 is made up of an insulating layer 2510a for preventing impurities from diffusing into the light-emitting element, and a flexible The substrate 2510b and the adhesive layer 2 that bonds the insulating layer 2510a and the flexible substrate 2510b together 510c. The substrate 2570 is a laminate having a structure for preventing diffusion of impurities into the light-emitting element. and a flexible substrate 2570b. 2570b and an adhesive layer 2570c that bonds the first and second layers 2570a and 2570b to each other.

[0461] The adhesive layer 2510c and the adhesive layer 2570c may be made of, for example, polyester or polyolefin. Polyimide, polycarbonate or acrylic Resins having siloxane bonds can be used. Materials including these can be used.

[0462] In addition, a sealing layer 2560 is provided between the substrate 2510 and the substrate 2570. It is preferable that the refractive index of the sealing material is larger than that of air. When light is extracted to the layer 2560 side, the sealing layer 2560 can also serve as an optical bonding layer. Cut.

[0463] A sealant may be formed on the outer periphery of the sealing layer 2560. As a result, the area surrounded by the substrate 2510, the substrate 2570, the sealing layer 2560, and the sealant The sealing layer 2560 may include a light emitting element 2550R. An inert gas (such as nitrogen or argon) may be filled. In addition, a desiccant may be added to the inert gas. Alternatively, a resin such as acrylic or epoxy may be used. The sealing material may be, for example, an epoxy resin or It is preferable to use glass frit. In addition, the material used for the sealing material is one that is resistant to moisture and acid. It is preferable to use a material that is opaque to the elements.

[0464] The display device 2501 also has a pixel 2502R. The pixel 2502R is a light-emitting model. It has a Joule 2580R.

[0465] The pixel 2502R includes a light emitting element 2550R and a power supply to the light emitting element 2550R. The transistor 2502t is a transistor that can The light emitting module 2580R includes a light emitting element 2550R and and a colored layer 2567R.

[0466] The light emitting element 2550R includes a lower electrode, an upper electrode, and an EL layer between the lower electrode and the upper electrode. As the light-emitting element 2550R, for example, any of the light-emitting elements described in Embodiments 1 to 3 can be used. Photonic elements can be applied.

[0467] In addition, a microcavity structure is adopted between the lower electrode and the upper electrode, and at a specific wavelength The light intensity may be increased.

[0468] In addition, when the sealing layer 2560 is provided on the side from which light is extracted, the sealing layer 2560 It contacts optical element 2550R and colored layer 2567R.

[0469] The colored layer 2567R is located so as to overlap the light emitting element 2550R. A part of the light emitted by 2550R passes through the colored layer 2567R and is emitted in the direction of the arrow shown in the figure. The light is emitted to the outside of the optical module 2580R.

[0470] Furthermore, the display device 2501 is provided with a light-shielding layer 2567BM in the light emission direction. The light blocking layer 2567BM is provided so as to surround the colored layer 2567R.

[0471] The colored layer 2567R may have a function of transmitting light in a specific wavelength range. For example, a color filter that transmits light in the red wavelength region and a color filter that transmits light in the green wavelength region A color filter that transmits light in the blue wavelength range, and a color filter that transmits light in the yellow wavelength range. A transparent color filter can be used. Each color filter is made of various materials. By using the above, printing method, inkjet method, etching method using photolithography technology, etc. It can be formed by, for example.

[0472] The display device 2501 is provided with an insulating layer 2521. The insulating layer 2521 is provided to flatten the unevenness caused by the pixel circuit. In addition, the insulating layer 2521 has a function of suppressing diffusion of impurities. This prevents the reliability of the transistors 2502t and the like from being reduced due to the diffusion of impurities. It can be suppressed.

[0473] The light emitting element 2550R is formed above the insulating layer 2521. The lower electrode of 550R is provided with a partition wall 2528 that overlaps an edge of the lower electrode. A spacer for controlling the distance between the substrate 2510 and the substrate 2570 is provided on the partition wall 2528. It may be formed.

[0474] The scanning line driver circuit 2503g(1) includes a transistor 2503t and a capacitor element 2503c. The driver circuit and the pixel circuit can be formed on the same substrate in the same process. do.

[0475] Moreover, wiring 2511 capable of supplying signals is provided on the substrate 2510 . A terminal 2519 is provided on the wiring 2511. C2509(1) is electrically connected to FPC2509(1). FPC2509(1) also transmits video signals, It has the function of supplying clock signals, start signals, reset signals, etc. 509(1) may have a printed wiring board (PWB) attached.

[0476] In addition, transistors with various structures can be used in the display device 2501. In 24(A), an example is given of a case where a bottom-gate transistor is applied. However, the present invention is not limited to this. For example, a top gate transistor shown in FIG. 24(B) may be used. The display device 2501 may be configured to use the same.

[0477] In addition, there is no particular restriction on the polarity of the transistor 2502t and the transistor 2503t. There is no fixed definition, and the structure has N-channel and P-channel transistors, A structure consisting of either a P-channel transistor or a P-channel transistor is used. In addition, the crystallinity of the semiconductor film used in the transistors 2502t and 2503t may be For example, an amorphous semiconductor film or a crystalline semiconductor film may be used. In addition, the semiconductor material may be a semiconductor of group 14 (e.g., a semiconductor having silicon). A compound semiconductor (including an oxide semiconductor), an organic semiconductor, etc. can be used. Either or both of the transistor 2502t and the transistor 2503t may be provided with an energy An oxide having a gap of 2 eV or more, preferably 2.5 eV or more, and more preferably 3 eV or more. The use of a semiconductor is preferable because the off-state current of a transistor can be reduced. The oxide semiconductor includes In-Ga oxide, In-M-Zn oxide (where M is Al, a, Y, Zr, La, Ce, Sn, Hf, or Nd).

[0478] <Explanation about touch sensor> Next, the touch sensor 2595 will be described in detail with reference to FIG. 23(C) corresponds to a cross-sectional view taken along dashed line X3-X4 shown in FIG. 23(B).

[0479] The touch sensor 2595 includes electrodes 2591 and electrodes 2592 arranged in a staggered pattern on a substrate 2590. 2592, an insulating layer 2593 covering the electrodes 2591 and 2592, and adjacent electrodes 25 91 and a wiring 2594 that electrically connects them.

[0480] The electrode 2591 and the electrode 2592 are formed using a light-transmitting conductive material. Examples of conductive materials having the above structure include indium oxide, indium tin oxide, and indium zinc oxide. Conductive oxides such as zinc oxide, zinc oxide doped with gallium can be used. A film containing graphene may also be used. The film containing graphene may be, for example, a film-like The graphene oxide-containing film formed on the substrate can be reduced to form the graphene oxide-containing film. An example of such a method is the application of heat.

[0481] For example, a light-transmitting conductive material is formed on the substrate 2590 by a sputtering method. After that, various pattern forming techniques such as photolithography are used to remove unnecessary parts. , an electrode 2591 and an electrode 2592 can be formed.

[0482] The material used for the insulating layer 2593 is, for example, a resin such as acrylic or epoxy. In addition to resins with siloxane bonds, silicon oxide, silicon oxynitride, aluminum oxide, Alternatively, inorganic insulating materials such as rubber may be used.

[0483] In addition, an opening reaching the electrode 2591 is provided in the insulating layer 2593, and a wiring 2594 is adjacent to the insulating layer 2593. The transparent conductive material is used to increase the aperture ratio of the touch panel. Since the electrode 2591 can be formed by the above-mentioned method, it can be suitably used for the wiring 2594. A material having a higher electrical conductivity than the electrode 2592 is preferable for the wiring 2594 because it can reduce electrical resistance. It can be used appropriately.

[0484] The electrodes 2592 extend in one direction, and a plurality of electrodes 2592 are provided in a stripe pattern. In addition, the wiring 2594 is provided so as to intersect with the electrode 2592.

[0485] A pair of electrodes 2591 are provided with one electrode 2592 interposed therebetween. A pair of electrodes 2591 are electrically connected.

[0486] In addition, the multiple electrodes 2591 are arranged in a direction that is not necessarily perpendicular to one electrode 2592. The electrodes do not necessarily have to be disposed at an angle greater than 0 degrees and less than 90 degrees.

[0487] The wiring 2598 is electrically connected to the electrode 2591 or the electrode 2592. A part of the wiring 2598 functions as a terminal. The wiring 2598 is made of, for example, aluminum. Aluminum, gold, platinum, silver, nickel, titanium, tungsten, chromium, molybdenum, iron, Use of metal materials such as ballast, copper, or palladium, or alloy materials containing such metal materials. can be done.

[0488] An insulating layer is provided to cover the insulating layer 2593 and the wiring 2594, and the touch sensor 2595 may be protected.

[0489] The connection layer 2599 electrically connects the wiring 2598 and the FPC 2509(2). .

[0490] The connection layer 2599 is made of an anisotropic conductive film (ACF). conductive film) and anisotropic conductive paste (ACP) Conductive Paste) can be used.

[0491] <Touch panel explanation 2> Next, the touch panel 2000 will be described in detail with reference to FIG. 23(A) corresponds to a cross-sectional view taken along dashed line X5-X6 shown in FIG. 23(A).

[0492] The touch panel 2000 shown in FIG. 25(A) is a display device 250 described in FIG. 24(A). 24(C) is bonded to the touch sensor 2595.

[0493] The touch panel 2000 shown in FIG. 25(A) is similar to the touch panel 2000 shown in FIG. 24(A) and FIG. 24(C). In addition to the components described above, it has an adhesive layer 2597 and an anti-reflection layer 2567p.

[0494] The adhesive layer 2597 is provided in contact with the wiring 2594. The substrate 2590 is attached to the substrate 2570 so that the sensor 2595 overlaps the display device 2501. In addition, it is preferable that the adhesive layer 2597 is transparent. The material 597 may be a thermosetting resin or an ultraviolet-curing resin. For example, Acrylic resin, urethane resin, epoxy resin, or siloxane resin can be used. This can be done.

[0495] The anti-reflection layer 2567p is provided at a position overlapping the pixel. For example, a circular polarizing plate can be used.

[0496] Next, for a touch panel having a different configuration from that shown in FIG. 25(A), FIG. 25(B) is used. I will use this to explain.

[0497] FIG. 25(B) is a cross-sectional view of the touch panel 2001. The panel 2001 is a touch panel 2000 shown in FIG. The location of the touch sensor 2595 is different. The different configurations are described in detail here. The description of touch panel 2000 is cited for the parts in which such a configuration can be used.

[0498] The colored layer 2567R is located so as to overlap the light-emitting element 2550R. The light-emitting element 2550R shown in FIG. 1 emits light toward the side where the transistor 2502t is provided. As a result, a part of the light emitted by the light emitting element 2550R passes through the colored layer 2567R, The light is emitted to the outside of light emitting module 2580R in the direction of the arrow shown in the figure.

[0499] The touch sensor 2595 is provided on the substrate 2510 side of the display device 2501. .

[0500] The adhesive layer 2597 is between the substrate 2510 and the substrate 2590 and is in contact with the display device 2501. Stick the Chisensor 2595 together.

[0501] As shown in FIG. 25(A) and (B), the light emitted from the light emitting element is guided by the substrate 2510 and the substrate 2520. It may be injected through either or both of the plates 2570 .

[0502] <Explanation of how to drive the touch panel> Next, an example of a method for driving a touch panel will be described with reference to FIGS. 26(A) and 26(B). cormorant.

[0503] FIG. 26A is a block diagram showing the configuration of a mutual capacitance type touch sensor. In (A), a pulse voltage output circuit 2601 and a current detection circuit 2602 are shown. In FIG. 26(A), the electrodes 2621 to which the pulse voltage is applied are designated as X1-X6, and the change in current The electrodes 2622 for detecting the change are shown as Y1-Y6, each having six wires. FIG. 26(A) shows a capacitance 2 formed by overlapping an electrode 2621 and an electrode 2622. 603. The electrodes 2621 and 2622 have functions interchangeably. This is also fine.

[0504] The pulse voltage output circuit 2601 is a circuit for applying pulses to the wirings X1-X6 in sequence. When a pulse voltage is applied to the wiring of X1-X6, the voltage that forms the capacitance 2603 An electric field is generated between the electrodes 2621 and 2622. The electric field generated between the electrodes is blocked by By using the change in the mutual capacitance of the capacitance 2603, the proximity of the object to be detected or A contact can be detected.

[0505] The current detection circuit 2602 detects the change in mutual capacitance of the capacitor 2603 between the wirings Y1-Y6. This is a circuit to detect changes in current at the sensor. The wiring of Y1-Y6 detects the proximity of the object to be detected, Or, if there is no contact, the detected current value will not change, but the proximity of the object to be detected, or When the mutual capacitance decreases due to contact, a change in the current value is detected. The detection may be performed using an integrating circuit or the like.

[0506] Next, FIG. 26B shows an input of the mutual capacitance type touch sensor shown in FIG. The timing chart of the output waveform is shown in FIG. 26(B). In FIG. 26B, the sensor detects the object to be detected. The two cases shown are when the sensor detects a sensor object (touch) and when the sensor detects a sensor object (touch). (B) shows the waveform of the voltage value corresponding to the current value detected in the wires Y1-Y6. .

[0507] A pulse voltage is applied to the wires X1-X6 in sequence, and the The waveform in the Y6 wiring changes. When there is no proximity or contact of the object to be detected, X1-X6 The waveforms of Y1-Y6 change uniformly according to the change in the voltage of the wiring. Or, at the point of contact, the current value decreases, and the corresponding voltage waveform also changes. do.

[0508] In this way, by detecting the change in mutual capacitance, the proximity or contact of the object to be detected can be detected. It is possible.

[0509] <Sensor circuit explanation> In FIG. 26A, only a capacitor 2603 is provided at the intersection of the wiring as a touch sensor. The configuration of a passive matrix touch sensor has been shown, but it has a transistor and a capacitor. An active matrix type touch sensor may be used. An example of a sensor circuit included in the sensor is shown in FIG.

[0510] The sensor circuit shown in FIG. 27 includes a capacitor 2603, a transistor 2611, and a transistor 2612 and a transistor 2613.

[0511] A signal G2 is applied to the gate of the transistor 2613, and a voltage is applied to either the source or drain of the transistor 2613. A voltage VRES is applied to one electrode of a capacitor 2603 and a transistor 2611. The transistor 2611 has a source and a drain that are electrically connected to each other. One of the source and drain of the transistor 2612 is electrically connected to the other of the source and drain of the transistor 2612. A signal G1 is applied to the gate of the transistor 2612, and a signal S is applied to the source or The other electrode of the drain is electrically connected to the wiring ML. The other electrode of the capacitor 2603 is connected to a voltage VS S is given.

[0512] Next, the operation of the sensor circuit shown in FIG. 27 will be described. First, the signal G2 is When a potential is applied to turn on the transistor 2613, the gate of the transistor 2611 is turned on. A potential corresponding to the voltage VRES is applied to the node n to which the input is connected. When a potential that turns off the transistor 2613 is applied, the potential of the node n is Retained.

[0513] Next, the mutual capacitance of the capacitor 2603 changes due to the proximity or contact of a detection object such as a finger. Accordingly, the potential of the node n changes from VRES.

[0514] The read operation applies a potential to the signal G1 that turns on the transistor 2612. A current flows through the transistor 2611 in accordance with the potential of the node n, that is, a current flows through the wiring ML. By detecting this current, the proximity or contact of the object to be detected can be detected. This can be done.

[0515] The transistors 2611, 2612, and 2613 include It is preferable to use an oxide semiconductor layer as the semiconductor layer in which the channel region is formed. By applying such a transistor to the transistor 2613, the potential of the node n can be It is possible to hold the voltage for a long period of time, and the operation of re-supplying VRES to node n (restart) is performed. This can reduce the frequency of refresh operations.

[0516] The structure described in this embodiment may be used in appropriate combination with structures described in other embodiments. can be done.

[0517] (Embodiment 8) In this embodiment, a display module and an electronic device including a light-emitting element of one embodiment of the present invention will be described. This will be described with reference to FIGS.

[0518] <Explanation about the display module> The display module 8000 shown in FIG. 28 includes an upper cover 8001 and a lower cover 8002. Between them, the touch sensor 8004 connected to the FPC8003 and the touch sensor 8005 connected to the FPC8006 are A display device 8006, a frame 8009, a printed circuit board 8010, and a battery 8011 are provided. do.

[0519] The light-emitting element of one embodiment of the present invention can be used for the display device 8006, for example.

[0520] The upper cover 8001 and the lower cover 8002 are connected to a touch sensor 8004 and a display device 8005. The shape and dimensions can be changed appropriately to match the size of 006.

[0521] The touch sensor 8004 is a resistive or capacitive touch sensor that is connected to the display device 8 8006. Also, the display device 8006 can be used as an opposing substrate (sealing substrate). It is also possible to provide a touch sensor function. It is also possible to provide an optical sensor in each pixel to form an optical touch sensor.

[0522] The frame 8009 has a function of protecting the display device 8006 and also a function of preventing the operation of the printed circuit board 8010. It also functions as an electromagnetic shield to block electromagnetic waves generated by the frame. The plate 8009 may function as a heat sink.

[0523] The printed circuit board 8010 includes a power supply circuit, a signal circuit for outputting a video signal, and a clock signal. The power supply circuit is provided with a signal processing circuit. Alternatively, the power source may be a battery 8011 provided separately. , this can be omitted when using a commercial power source.

[0524] In addition, the display module 8000 includes components such as a polarizing plate, a retardation plate, and a prism sheet. It may be added.

[0525] <Electronic device information> 29(A) to 29(G) are diagrams showing electronic devices. These electronic devices are A body 9000, a display unit 9001, a speaker 9003, and operation keys 9005 (power switch, etc.) includes an operation switch), a connection terminal 9006, a sensor 9007 (force, displacement, position, speed, Acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substances, sound, time, hardness, electricity Measures field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared rays The sensor 9005 may also include a microphone 9008, etc. 007 may have a function of measuring biological information, such as a pulse sensor or a fingerprint sensor.

[0526] The electronic devices illustrated in FIGS. 29A to 29G can have various functions. For example, the function to display various information (still images, videos, text images, etc.) on the display, Sensor function, calendar, date or time display function, various software ( A function to control processing by a program, wireless communication function, and various functions using wireless communication function Functions for connecting to computer networks, transmitting various data using wireless communication functions, or receiving the program or data recorded on the recording medium, and displaying the program or data. The display unit may have a function to display the information on the display unit. The functions that the electronic device shown in the figure can have are not limited to these, and the electronic device may have a variety of functions. Although not shown in FIG. 29(A) to FIG. 29(G), the electronic device may include The electronic device may have a plurality of display units. The function to take pictures, record videos, and store the images on a recording medium (external or built-in to the camera) ) and a function for displaying the captured image on a display unit.

[0527] The electronic devices shown in FIGS. 29A to 29G will be described in detail below.

[0528] FIG. 29A is a perspective view showing a portable information terminal 9100. The display unit 9001 has flexibility. The display unit 9001 can be incorporated along the screen. The device is equipped with a touch sensor, and can be operated by touching the screen with a finger or a stylus. By touching the icon displayed on the display 9001, the application can be started. can.

[0529] FIG. 29B is a perspective view showing a portable information terminal 9101. For example, the device has one or more functions selected from a telephone, a notebook, an information viewing device, etc. Specifically, the mobile information terminal 9101 can be used as a smartphone. Although the speaker 9003, the connection terminal 9006, the sensor 9007, etc. are omitted in the figure, The mobile information terminal 9100 shown in FIG. 29(A) can be installed in the same position. The information terminal 9101 can display text and image information on multiple surfaces. For example, Three operation buttons 9050 (also called operation icons or simply icons) are displayed on the display unit 900. The information 9051 shown in the dashed rectangle can be displayed on one side of the display unit 90. 01. An example of the information 9051 is an e-mail Displays to notify you of incoming calls, SNS (social networking services), etc. , subject of email or SNS, sender name of email or SNS, date and time, time, Battery level, antenna reception strength, etc. Or, information 9051 is displayed. Instead of the information 9051, an operation button 9050 or the like may be displayed at that position.

[0530] FIG. 29C is a perspective view showing a portable information terminal 9102. , and has a function of displaying information on three or more faces of the display unit 9001. An example is shown in which information 9053 and information 9054 are displayed on different sides. The user of the portable information terminal 9102 holds the portable information terminal 9102 in the breast pocket of the clothes. In this state, the display (information 9053 in this case) can be confirmed. The telephone number or name of the caller is displayed on the mobile information terminal 9102 so that it can be observed from above. The user can read the display without taking the mobile information terminal 9102 out of his pocket. You can check the number and decide whether to answer the call or not.

[0531] 29(D) is a perspective view showing a wristwatch-type portable information terminal 9200. The 9200 is used for mobile phone calls, e-mail, document browsing and writing, music playback, and Internet communications. It is possible to execute various applications such as computer games. The display unit 9001 has a curved display surface, and displays information along the curved display surface. In addition, the portable information terminal 9200 can perform short-distance wireless communication according to a communication standard. For example, by communicating with a wireless headset, The mobile information terminal 9200 also has a connection terminal 9006. It has a connector and can directly exchange data with other information terminals. Charging can also be performed via the connection terminal 9006. Power may also be supplied wirelessly without going through 6.

[0532] 29(E), (F), and (G) are perspective views showing a foldable portable information terminal 9201. FIG. 29E is a perspective view of the portable information terminal 9201 in an unfolded state. (F) shows the mobile information terminal 9201 being changed from one of the unfolded and folded states to the other. FIG. 29(G) is a perspective view of the portable information terminal 9201 in a folded state. The portable information terminal 9201 is highly portable when folded and is unfolded. When the display is turned on, the seamless, wide display area provides excellent visibility of the display. The display unit 9001 of the display device 9001 is made up of three housings 9000 connected by hinges 9055. The two housings 9000 are supported by the hinge 9055. The portable information terminal 9201 can be reversibly transformed from an unfolded state to a folded state. For example, the portable information terminal 9201 can be bent with a radius of curvature of 1 mm or more and 150 mm or less. It can be done.

[0533] In addition, the electronic device may be, for example, a television device (a television or a television receiver (also called monitors), computer monitors, digital cameras, digital video cameras, Digital photo frames, mobile phones (also called mobile phones or mobile phone devices), goggle-type Displays (head-mounted displays), portable game consoles, portable information terminals, audio playback Examples include live video games, pachinko machines, and other large game machines.

[0534] FIG. 30A shows an example of a television device. The television device 9300 includes a housing 9 A display unit 9001 is built into the display unit 9000. Here, the display unit 9001 is supported by a stand 9301. This shows a configuration that supports 000.

[0535] The television device 9300 shown in FIG. 30A is operated using an operation switch provided in the housing 9000. This can be done by a separate remote control 9311 or a display unit 90 The display unit 9001 may be provided with a touch sensor, and the operation can be performed by touching the display unit 9001 with a finger or the like. The remote control operation device 9311 may display information to be output from the remote control operation device 9311. The remote control 9311 may have an operation key or a touch panel. The panel allows the user to control the channel and volume, and is displayed on the display unit 9001. You can manipulate the video.

[0536] The television device 9300 includes a receiver, a modem, and the like. It is also possible to receive general television broadcasts by wired or wireless connection via a modem. By connecting to a communication network, one-way (sender to receiver) or two-way It is also possible to communicate information (between a sender and a receiver, or between receivers).

[0537] In addition, the electronic device or lighting device of one embodiment of the present invention has flexibility and can be used in a house or a building. It can also be installed along the curved surfaces of walls or exterior walls, or the interior or exterior of a car. be.

[0538] FIG. 30(B) shows the exterior of the automobile 9700. FIG. 30(C) shows the driver's seat of the automobile 9700. The automobile 9700 includes a body 9701, wheels 9702, a dashboard 9703, a rack The display device or the light-emitting device of one embodiment of the present invention includes an automobile 9700. For example, the display portion 9710 to the display portion 9720 shown in FIG. The display device or the light-emitting device of one embodiment of the present invention can be provided in the display portion 9715.

[0539] The display portion 9710 and the display portion 9711 are display devices provided on a windshield of an automobile. In a display device or a light-emitting device according to one embodiment of the present invention, electrodes and wirings are formed using a light-transmitting conductive material. By making it from a transparent material, the other side can be seen through, creating a so-called see-through state. If the display unit 9710 or the display unit 9711 is in a see-through state, the automobile 97 00 while driving. Therefore, the display device or A light-emitting device or the like can be installed on the windshield of an automobile 9700. In the case where a transistor for driving a light-emitting device is provided, an organic semiconductor material is used. A light-transmitting transistor, such as an organic transistor using a semiconductor or a transistor using an oxide semiconductor, A transistor may be used.

[0540] The display unit 9712 is a display device provided on a pillar part. By displaying the image from the imaging means on the display unit 9712, the view blocked by the pillars can be cleared. The display unit 9713 is a display device provided in the dashboard. For example, an image captured by an imaging means provided on the vehicle body is displayed on the display unit 9713. This can complement the view obstructed by the dashboard. By projecting images from an imaging device installed in the vehicle, blind spots are filled and safety is improved. In addition, by projecting an image that complements the invisible parts, it is possible to make the image look more natural. This allows for easy safety checks.

[0541] FIG. 30(D) shows the interior of a car with bench seats for the driver and passenger. The display unit 9721 is a display device provided in a door section. By displaying an image from the imaging means on the display unit 9721, the view blocked by the door can be cleared. The display unit 9722 is a display device provided on the handle. The display unit 9723 is a display device provided in the center of the seat surface of the bench seat. The display device is installed on the seat or backrest, and the heat generated by the display device is It can also be used as a seat heater using this as a heat source.

[0542] The display unit 9714, the display unit 9715, or the display unit 9722 displays navigation information, speech such as the odometer, tachometer, mileage, fuel level, gear status, and air conditioning settings. In addition, various other information can be provided. In addition, th...

Claims

[Claim 1] A light-emitting device having a host material and a guest material, The host material includes a first organic compound and a second organic compound, The guest material has a function of being able to exhibit fluorescence, the first organic compound has a difference between a singlet excitation energy level and a triplet excitation energy level greater than 0 eV and equal to or less than 0.2 eV; one of the first organic compound and the second organic compound has a HOMO level equal to or higher than a HOMO level of the other of the first organic compound and the second organic compound, and has a LUMO level equal to or higher than a LUMO level of the other of the first organic compound and the second organic compound; A light-emitting element characterized by:

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