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

Abstract

To provide a light-emitting element with high luminous efficiency, in which a material emitting fluorescence is used as a light-emitting material.SOLUTION: A light-emitting element includes a pair of electrodes and an EL layer provided between the pair of electrodes. The EL layer includes a first organic compound, a second organic compound, and a guest material. The first organic compound has a function of emitting a thermally activated delayed fluorescence at room temperature. The guest material has a function of emitting fluorescence. The HOMO of the first organic compound has an energy level of more than or equal to the HOMO of the second organic compound. The LUMO of the first organic compound has an energy level of less than or equal to the LUMO of the second organic compound.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One embodiment of the present invention is a light-emitting layer that emits light when an electric field is applied between a pair of electrodes. and a display device, an electronic device, and a lighting device each having the light-emitting element. do.

[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. One aspect of the invention is a process, machine, manufacture, or composition of matter. Therefore, the present invention disclosed in this specification more specifically relates to the In one embodiment, the present invention relates to a semiconductor device, a display device, a liquid crystal display device, a light-emitting device, a lighting device, and the like. As examples, a device, a power storage device, a storage device, a driving method thereof, or a manufacturing method thereof These can be listed as follows. [Background technology]

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

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

[0005] A light-emitting element in which an organic material is used as the light-emitting material and an EL layer containing the light-emitting material is provided between a pair of electrodes. In the case of a device (for example, an organic EL device), applying a voltage between a pair of electrodes causes light to flow from the cathode Electrons are injected from the cathode and holes are injected from the anode into the luminescent EL layer, causing a current to flow. The injected electrons and holes are then recombined to excite the light-emitting organic material. The excited light-emitting organic material is then in a luminescent state, and light can be emitted from the excited light-emitting organic material.

[0006] The types of excited states that organic materials form are the singlet excited state (S1) and the triplet excited state (S2). The emission from the singlet excited state is fluorescence, and the emission from the triplet excited state is phosphorescence. The statistical generation ratio of these in a light-emitting element is S1:T1=1 Therefore, it is more preferable to use a light-emitting element that uses a phosphorescent material than a light-emitting element that uses a fluorescent material. Therefore, a light-emitting element in which the triplet excited state is used can obtain a higher luminous efficiency. In recent years, there has been active development of light-emitting devices using phosphorescent materials that can convert the state of matter into light. It is being carried out.

[0007] In addition, materials capable of converting part of the triplet excited state into luminescence have been developed, such as thermally activated delayed Thermally activated delayed fluorescence In thermally activated delayed fluorescent materials, the triplet excited state is converted into the reverse state. Intersystem crossing generates a singlet excited state, which is then converted into luminescence. Document 1 and Patent Document 2 disclose materials that emit thermally activated delayed fluorescence.

[0008] 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, , and efficient emission from the singlet excited state, i.e., high fluorescence quantum yield. However, it is difficult to design a light-emitting material that satisfies both of these requirements at the same time. do.

[0009] Therefore, in a light-emitting device having a thermally activated delayed phosphor and a material that emits fluorescence, The singlet excitation energy of the activated delayed fluorescent material is transferred to a fluorescent material, causing the fluorescent material to emit fluorescence. A method for obtaining light emission from a material that emits light has been proposed (see Patent Document 3). [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-241374 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-24830 [Patent Document 3] Japanese Patent Application Laid-Open No. 2014-45179 Summary of the Invention [Problem to be solved by the invention]

[0011] In a light-emitting device having a thermally activated delayed phosphor and a fluorescent material, the luminous efficiency is To increase the photon density, it is important to efficiently generate the singlet excited state from the triplet excited state. In addition, the excited state of the thermally activated delayed fluorescent material can be efficiently converted to the excited state of the fluorescent material. The transfer of energy is important.

[0012] In one embodiment of the present invention, in a light-emitting element having a fluorescent material as a light-emitting material, Another object of the present invention is to provide a light-emitting element with high light efficiency. Another object of the present invention is to provide a light-emitting element with high reliability. It is an object of the present invention to provide a light-emitting element with high luminous efficiency and high reliability. An object of one embodiment of the present invention is to provide a novel light-emitting element. In one embodiment, the object is to provide a novel light-emitting element with high luminous efficiency and reduced power consumption. This is one of the topics.

[0013] The above description of the problem does not preclude the existence of other problems. The embodiment does not necessarily have to solve all of these problems. Problems other than those mentioned above can be solved by the specification. It is clear from the description of the specification, etc. that the problems other than those mentioned above cannot be extracted from the description of the specification, etc. It is possible to issue it. [Means for solving the problem]

[0014] One embodiment of the present invention is a light-emitting device having a pair of electrodes and an EL layer provided between the pair of electrodes. The device includes an EL layer including a first organic compound, a second organic compound, and a guest material. the first organic compound has a function of exhibiting thermally activated delayed fluorescence at room temperature; The guest material has a function capable of exhibiting fluorescence, and the HOMO of the first organic compound is The second organic compound has an energy level equal to or higher than the HOMO of the second organic compound and has an energy level equal to or higher than the LUMO of the first organic compound. has an energy level below the LUMO of the second organic compound. It is an element.

[0015] Another embodiment of the present invention is a light-emitting diode (LED) including a pair of electrodes and an EL layer provided between the pair of electrodes. The EL layer is a light-emitting element including a first organic compound, a second organic compound, and a guest and a material, wherein the first organic compound has a function capable of exhibiting thermally activated delayed fluorescence at room temperature. The guest material has a function of exhibiting fluorescence, and the acid of the first organic compound The oxidation potential of the first organic compound is equal to or less than the oxidation potential of the second organic compound, and the reduction potential of the first organic compound is equal to or less than the oxidation potential of the second organic compound. The light-emitting element is characterized in that the reduction potential of the organic compound of formula 2 is equal to or higher than that of the organic compound of formula 2.

[0016] In each of the above structures, the singlet excitation energy level and the triplet excitation energy level of the first organic compound are It is preferable that the difference from the electron transport energy level is more than 0 eV and 0.2 eV or less.

[0017] In each of the above structures, the guest material preferably emits light.

[0018] In each of the above structures, the first organic compound has a first π-electron-deficient heteroaromatic skeleton. and a first π-electron rich heteroaromatic skeleton, and the second organic compound has a second π-electron rich heteroaromatic skeleton. It is preferable to have a π-electron deficient heteroaromatic skeleton and a second π-electron rich heteroaromatic skeleton.

[0019] In each of the above structures, the first π-electron deficient heteroaromatic skeleton is a diazine skeleton or or a triazine skeleton, and the first π-electron-rich heteroaromatic skeleton is an acridine skeleton, Phenoxazine skeleton, or 3-(9-phenyl-9H-carbazol-3-yl)-9 H-carbazole skeleton, and The deficient heteroaromatic skeleton has a pyridine skeleton or a diazine skeleton and a second π-electron excess. The heteroaromatic skeleton is a furan skeleton, a thiophene skeleton, a fluorene skeleton, or a pyrrole skeleton. It is preferable that the present invention has one or more of the following characteristics selected from the above.

[0020] In each of the above-mentioned configurations, the weight ratio of the second organic compound to the first organic compound (the second organic compound The ratio of the organic compound to the first organic compound is 1:0.05 to 1:0.5, and the ratio of the second organic compound to the second organic compound is 1:0.05 to 1:0.5. The weight ratio of the second organic compound to the guest material (second organic compound: guest material) is 1:0.001 to 1: Preferably it is 0.01.

[0021] Another embodiment of the present invention is a light-emitting element having any of the above structures, a color filter, a seal, or a light-emitting device. Another embodiment of the present invention is a display device including the display device. The electronic device of the present invention has a touch sensor function and a housing. One embodiment is a lighting device having a light-emitting element having any of the above structures and a housing or a touch sensor function. is. [Effects of the Invention]

[0022] According to one embodiment of the present invention, in a light-emitting element including a fluorescent material as a light-emitting material, A light-emitting element with high emission efficiency can be provided. Alternatively, according to one embodiment of the present invention, a light-emitting element having high emission efficiency can be provided. According to one embodiment of the present invention, a light-emitting element with high light-emitting efficiency and high reliability can be provided. A novel light-emitting element can be provided. Alternatively, according to one embodiment of the present invention, Therefore, a novel light-emitting element with reduced power consumption can be provided.

[0023] The description of these effects does not preclude the existence of other effects. An embodiment does not necessarily have to have all of these effects. The above will be made clear from the description, drawings, claims, etc. It is possible to extract other effects from the descriptions in the aspects and claims. [Brief explanation of the drawings]

[0024] [Figure 1] 1A and 1B are schematic cross-sectional views illustrating a light-emitting element of one embodiment of the present invention. [Figure 2] 1A and 1B are diagrams illustrating the correlation of energy levels in a light-emitting element of one embodiment of the present invention. [Figure 3] 1A and 1B are a schematic cross-sectional view illustrating a light-emitting element of one embodiment of the present invention and a diagram illustrating the correlation of energy levels in a light-emitting layer. [Figure 4] 1A and 1B are a schematic cross-sectional view illustrating a light-emitting element of one embodiment of the present invention and a diagram illustrating the correlation of energy levels in a light-emitting layer. [Figure 5] 1A and 1B are a block diagram and a circuit diagram illustrating a display device of one embodiment of the present invention. [Figure 6] FIG. 1 is a perspective view illustrating an example of a touch panel of one embodiment of the present invention. [Figure 7] 1A and 1B are cross-sectional views illustrating examples of a display device and a touch sensor according to one embodiment of the present invention. [Figure 8] FIG. 1 is a cross-sectional view illustrating an example of a touch panel of one embodiment of the present invention. [Figure 9] 1A and 1B are a block diagram and a timing chart of a touch sensor of one embodiment of the present invention. [Figure 10] FIG. 1 is a circuit diagram of a touch sensor according to one embodiment of the present invention. [Figure 11] FIG. 1 is a perspective view illustrating a display module of one embodiment of the present invention. [Figure 12] 1A to 1C illustrate electronic devices of one embodiment of the present invention. [Figure 13] 1A to 1C illustrate a lighting device according to one embodiment of the present invention. [Figure 14] 1 is a cross-sectional view illustrating a light-emitting device according to Examples 1 and 2. FIG. [Figure 15] FIG. 2 is a diagram illustrating transient fluorescence characteristics of a host material according to Example 1. [Figure 16] FIG. 2 is a graph showing current efficiency-luminance characteristics of a light-emitting element according to Example 1. [Figure 17] FIG. 2 is a graph showing current-voltage characteristics of a light-emitting element according to Example 1. [Figure 18] FIG. 2 is a graph showing the external quantum efficiency-luminance characteristics of the light-emitting element according to the first embodiment. [Figure 19] FIG. 2 is a graph showing electroluminescence spectra of a light-emitting element according to Example 1. [Figure 20] FIG. 10 is a graph showing current efficiency-luminance characteristics of a light-emitting element according to Example 2. [Figure 21] FIG. 10 is a graph showing current-voltage characteristics of a light-emitting element according to Example 2. [Figure 22] FIG. 10 is a graph showing the external quantum efficiency-luminance characteristics of a light-emitting element according to Example 2. [Figure 23] FIG. 10 is a graph showing electroluminescence spectra of a light-emitting element according to Example 2. [Figure 24] FIG. 10 is a graph showing current efficiency-luminance characteristics of a light-emitting element according to Example 2. [Figure 25] FIG. 10 is a graph showing current-voltage characteristics of a light-emitting element according to Example 2. [Figure 26] FIG. 10 is a graph showing the external quantum efficiency-luminance characteristics of a light-emitting element according to Example 2. [Figure 27] FIG. 10 is a graph showing electroluminescence spectra of a light-emitting element according to Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the above description, and the embodiments and details thereof may be modified without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the embodiments described below. It is not to be construed as being limited to the content.

[0026] In addition, the position, size, range, etc. of each component shown in the drawings etc. are not necessarily specified for ease of understanding. It may not represent the actual position, size, range, etc. Therefore, the disclosed invention The position, size, range, etc. are not necessarily limited to those disclosed in the drawings, etc.

[0027] In addition, in this specification, ordinal numbers such as 1st, 2nd, etc. are used for convenience. Therefore, for example, "first" may be changed to "second" "the" or "third" can be used as appropriate for explanation. The ordinal numbers listed in the specification do not match the ordinal numbers used to identify an aspect of the present invention. There are cases where this happens.

[0028] In addition, in this specification and the like, when explaining the configuration of the invention using drawings, the same The reference numerals may be commonly used even among different drawings.

[0029] 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

[0030] In this specification and the like, the singlet excited state refers to a singlet state having excitation energy. The S1 level is the lowest singlet excited energy level and is the most The excited energy level of the singlet excited state is the lowest. The triplet excited state is the highest excited The T1 level is a triplet state with triplet excitation energy. It is the lowest level of the triplet excited state and the lowest excited energy level of the triplet excited state. In this specification and the like, the terms "singlet excited state" and "singlet excited energy level" are used. Even if the electrons are in the lowest excited singlet state and the S1 level, Even when written as singlet and triplet excited energy levels, the lowest triplet It may represent the first excited state and the T1 level.

[0031] In this specification, the term "fluorescent material" refers to a material that emits light at the lowest level (S1 level) of the singlet excited state. Phosphorescent materials are materials that emit light in the visible light region when they relax from the ion-exchange state to the ground state. When the lowest excited state (T1 level) relaxes to the ground state, visible light is emitted at room temperature. In other words, phosphorescent materials are materials that can convert triplet excitation energy into It is one of the materials that can be converted into visible light.

[0032] In this specification and the like, a thermally activated delayed fluorescent substance is a substance that emits light by reverse intersystem crossing due to thermal activation. Thermally activated delayed fluorescent materials are materials that can generate a singlet excited state from a triplet excited state. For example, materials that emit TADF can emit light by reverse intersystem crossing from triplet excited states alone. It may contain a material capable of generating a singlet excited state. The material may include a combination of two materials that form a composite (also called an exciplex). stomach.

[0033] Thermally activated delayed fluorescent materials are materials whose triplet excited state and singlet excited state are close to each other. More specifically, the difference in energy levels between the triplet excited state and the singlet excited state is 0 eV. In other words, materials that emit TADF light with a wavelength of 0.2 eV or less are preferred. In materials that can generate a singlet excited state from a triplet excited state by reverse intersystem crossing, The difference in energy level between the doublet excited state and the singlet excited state is greater than 0 eV and less than 0.2 eV. The difference in energy levels between the triplet excited state and the singlet excited state in the exciplex is 0e It is preferable that the potential is greater than V and not more than 0.2 eV.

[0034] In the present specification and the like, the emission energy of thermally activated delayed fluorescence is The emission peak (including the shoulder) on the shortest wavelength side of the light. The phosphorescence energy or triplet excitation energy is the phosphorescence energy at the shortest wavelength side of phosphorescence emission. The emission peak (including the shoulder) is the emission peak. ) environment, it can be observed by time-resolved photoluminescence. .

[0035] In this specification, room temperature refers to any temperature between 0°C and 40°C.

[0036] (Embodiment 1) In this embodiment, a light-emitting element of one embodiment of the present invention will be described below with reference to FIGS. 1 and 2. explain.

[0037] <1. Example of light-emitting element configuration> First, the structure of a light-emitting element of one embodiment of the present invention will be described below with reference to FIG.

[0038] The light-emitting element 150 includes an EL layer 1 provided between a pair of electrodes (electrode 101 and electrode 102). 00. The EL layer 100 has at least a light-emitting layer 120. In the description, the electrode 101 is an anode and the electrode 102 is a cathode. The configuration of 50 can also be reversed.

[0039] 1A includes a functional layer in addition to the light-emitting layer 120. The layers are composed of a hole injection layer 111, a hole transport layer 112, an electron transport layer 118, and an electron injection layer 119. The configuration of the EL layer 100 is not limited to the configuration shown in FIG. layer 111, hole transport layer 112, electron transport layer 118, and electron injection layer 119. Alternatively, the EL layer 100 may be configured to have at least one of the hole- or electron-injecting layer. Reduce the barrier, improve hole or electron transport, inhibit hole or electron transport, Or, it has other functional layers that have functions such as being able to suppress the quenching phenomenon caused by the electrode. It may also be configured as follows.

[0040] FIG. 1B is a cross-sectional view showing an example of the light-emitting layer 120 shown in FIG. 1A. The light-emitting layer 120 shown in FIG. 1B includes an organic compound 131, an organic compound 132, and a guest material. It has 133 fees.

[0041] It is preferable to use a thermally activated delayed fluorescent substance as the organic compound 131. is the ability to convert triplet excitation energy into singlet excitation energy by reverse intersystem crossing. Therefore, at least a part of the triplet excitation energy generated in the light-emitting layer 120 The singlet excited energy is converted into singlet excited energy by the organic compound 131. The energy is transferred to the guest material 133 and extracted as fluorescent light. To do this, we first investigated the relationship between the singlet and triplet excited energy levels of organic compound 131. The difference is preferably greater than 0 eV and less than 0.2 eV. The excited energy level is higher than the singlet excited energy level of the guest material 133, and the organic The triplet excited energy level of the compound 131 is higher than the singlet excited energy level of the guest material 133. By doing so, the triplet excitation energy of the organic compound 131 is preferably higher than the The energy level can be brought closer to the singlet excited energy level.

[0042] The organic compound 132 is preferably selected so as not to deactivate the organic compound 131 and the guest material 133. A material with a large band gap is preferred. The energy levels are higher than the singlet excited energy levels of the organic compound131 and the guest material133. The triplet excited energy level of organic compound 132 is preferably higher than that of organic compound 1. It is preferable that the triplet excitation energy level of the guest material 133 is higher than that of the guest material 31. In addition to the organic compound 132, other compounds having similar functions may also be contained in the light-emitting layer 120. It is okay to use it.

[0043] The guest material 133 may be a light-emitting organic material. The material is a material that has the ability to emit fluorescence (hereinafter also referred to as a fluorescent material). In the following description, a configuration in which a fluorescent material is used as the guest material 133 is used. The guest material 133 may be interpreted as a fluorescent material.

[0044] <2. Light-emitting mechanism of light-emitting elements> First, the light emitting mechanism of the light emitting element 150 will be described below.

[0045] In the light-emitting element 150 of one embodiment of the present invention, a pair of electrodes (electrode 101 and electrode 102) By applying a voltage between the cathode and the anode, electrons flow from the cathode and holes flow from the anode. The electrons and holes are then injected into the EL layer 100, causing a current to flow. As a result, the guest material 133 in the light-emitting layer 120 of the EL layer 100 is excited. The excited guest material 133 emits light.

[0046] Light emission from the guest material 133 is obtained through the following three processes. (α) Direct recombination process in guest materials (β) Energy transfer process from thermally activated delayed fluorescent substance (γ) Energy transfer process from the host material

[0047] <(α) Direct recombination process in guest materials> First, to explain the direct recombination process in the guest material 133, we first show the energy The following diagram illustrates the correlation between the energy levels. As shown below. ·Host1(131):Organic compound 131 ·Host2(132):Organic compound 132 Guest (133): Guest material 133 (fluorescent material) ·S A : The lowest singlet excitation energy level of organic compound 131. T A : The lowest triplet excitation energy level of organic compound 131. ·S H : The lowest singlet excitation energy level of organic compound 132. T H : The lowest triplet excited energy level of organic compound 132. ·S G : The lowest singlet excitation energy level of guest material 133 (fluorescent material) T G : The lowest triplet excitation energy level of guest material 133 (fluorescent material)

[0048] As shown in FIG. 2A, carriers (electrons and holes) are transported to the guest material 133. When the guest material 133 is recombined with the guest material 133, an excited state is formed. When the excited state of 33 is a singlet excited state, fluorescence is obtained. When the excited state of 3 is a triplet excited state, it undergoes thermal deactivation.

[0049] In the direct recombination process of carriers in the guest material (α), guest material 13 If the fluorescence quantum yield of 3 is high, the guest material 133 will efficiently emit light from the singlet excited state. However, the triplet excited state of the guest material 133 does not contribute to the emission.

[0050] <(β) Energy transfer process from thermally activated delayed fluorescent substance> Next, to explain the energy transfer process between the organic compound 131 and the guest material 133, FIG. 2(B) shows a schematic diagram for explaining the correlation of the energy levels. The notations and symbols are the same as those in FIG. 2(A).

[0051] When the carriers recombine in the organic compound 131, the excited state of the organic compound 131 becomes At this time, the excited state of the organic compound 131 is a singlet excited state, and Machine Compound 131 S A However, the guest material 133 S G If it is higher than the route in Figure 2(B), As shown in E1, the singlet excitation energy of organic compound 131 is S A From guest material 133S G The guest material 133 enters the singlet excited state. The guest material 133 in the singlet excited state emits fluorescent light.

[0052] The singlet excited state of the organic compound 131 is converted to the triplet excited state of the guest material 133. The energy transfer from the singlet ground state to the triplet excited state in the guest material 133 is Since direct transition is forbidden, it is unlikely to be the main energy transfer process. That is, as shown in the following general formula (G1), the singlet excited state of the organic compound 131 is From this state, energy transfer to the singlet excited state of the guest material 133 is important.

[0053] 1 A * + 1 G → 1 A+ 1 G * (G1)

[0054] In general formula (G1), 1 A * and 1 G * are organic compounds 131 and 132, respectively. represents the singlet excited state of the material 133, 1 A and 1 G is organic compound 131 and represents the singlet ground state of the guest material 133.

[0055] Next, an excited state of the organic compound 131 is generated. If it is a triplet excited state, Fluorescence emission is obtained through the following two processes.

[0056] Since organic compound 131 is a thermally activated delayed fluorescent material, the first step is shown in Figure 2(B). As shown in Route A1 of the organic compound 131, A from reverse intersystem crossing (upconvergence) By S A Excitation energy is transferred to

[0057] The second step is the S of organic compound 131. AHowever, the guest material 133 S G When the S of organic compound 131 is higher than 1, as shown in Route E1 of FIG. 2(B), A Karaage Stock material 133 S G The excitation energy is transferred to the guest material 133, and the guest material 133 enters a singlet excited state. Fluorescence is emitted from the guest material 133 in the singlet excited state.

[0058] The above-mentioned first and second processes are represented by the following general formula (G2).

[0059] 3 A * + 1 G → (reverse intersystem crossing) → 1 A * + 1 G → 1 A+ 1 G * (G2)

[0060] In general formula (G2), 3 A * represents the triplet excited state of organic compound 131, 1 A * and 1 G * represent the singlet excited states of the organic compound 131 and the guest material 133, respectively. Represents, 1 A and 1 G is the singlet group of the organic compound 131 and the guest material 133, respectively. Represents the bottom state.

[0061] As shown in general formula (G2), the triplet excitation of organic compound 131, which is a thermally activated delayed fluorescent substance, Waking state ( 3 A * ) to the singlet excited state ( 1 A * ) is generated, and then the guest material 133 enters the singlet excited state ( 1 G *) to excitation energy moves.

[0062] All the energy transfer processes from the above (β) thermally activated delayed fluorescent substance If the transfer process occurs efficiently, the triplet excitation energy and singlet excitation energy of organic compound 131 will be The energy of the guest material 133 is efficiently increased to the singlet excited state ( 1 G * ) This allows for highly efficient light emission.

[0063] However, the singlet excited state of the organic compound 131 is converted to the singlet excited state of the guest material 133. Before the excitation energy is transferred, the organic compound 131 converts the excitation energy into light or heat. If the electrons are released and deactivated, the luminescence efficiency will decrease. As a result, reverse intersystem crossing from the triplet excited state to the singlet excited state occurs in organic compound 131. If the efficiency of the process of route A1 decreases, the luminous efficiency will also decrease. , Organic Compound 131 T A However, the T of guest material 133 G If it is lower than S A ≧S G > T G >T A Therefore, T A and S A As a result, the energy difference between Since the reverse intersystem crossing of route A1 in 2(B) becomes difficult to occur, the following route E1 The efficiency of the energy transfer process also decreased, resulting in a low generation efficiency of the singlet excited state of the guest material 133. Therefore, the T of organic compound 131 A T of guest material 133 G Higher than That is, the emission energy of the thermally activated delayed fluorescence of the organic compound 131 is preferably Preferably, the phosphorescence energy is higher than that of the phosphorescent material 133.

[0064] At this time, as shown in route E2 of FIG. 2(B), T A From guest material Fee 133 T G When excitation energy is transferred to the Therefore, the route with fewer energy transfer processes shown in route E2 in Figure 2(B) is the route with fewer guest materials. The generation efficiency of the triplet excited state of 33 can be reduced, and the thermal deactivation of the excitation energy can be reduced. To achieve this, the organic compound 131 and the guest material 133 are It is preferable that the weight ratio of the guest material 133 is low. The weight ratio of the organic compound 31 to the guest material 133 (organic compound 131:guest material 133) is preferably Preferably, it is 1:0.001 to 1:0.05, and more preferably, it is 1:0.001 to The ratio is 1:0.01.

[0065] When the direct recombination process in the guest material 133 becomes dominant, the guest A large number of triplet excited states of material 133 are generated, and the excitation energy is thermally deactivated. In other words, the direct recombination in the guest material (α) causes a loss of luminous efficiency. The rate of energy transfer from the (β) thermally activated delayed fluorescent substance is higher than that of the (β) thermally activated delayed fluorescent substance. The generation efficiency of the triplet excited state of the ion exchange material 133 can be reduced, and the thermal loss of the excitation energy can be reduced. To achieve this, it is desirable to use organic compound 131 and The weight ratio of the host material 133 is preferably lower than the weight ratio of the guest material 133. Specifically, , the weight ratio of the organic compound 131 to the guest material 133 (organic compound 131:guest material 133 ) is preferably 1:0.001 to 1:0.05, more preferably 1 :0.001 to 1:0.01.

[0066] <(γ) Energy transfer process from the host material> Next, the organic compound 132 transfers energy to the organic compound 131 or the guest material 133. To explain the electron transfer process, a schematic diagram illustrating the correlation of energy levels is shown in Figure 2(C). The notations and symbols in FIG. 2(C) are the same as those in FIG. 2(A).

[0067] When the carriers recombine in the organic compound 132, the excited state of the organic compound 132 becomes At this time, the excited state of the organic compound 132 is a singlet excited state, and the organic compound 132 S H However, S of organic compound 131 A and S of guest material 133 G If it is higher than Organic Compound 132 S H From guest material 133 S G The singlet excitation energy is transferred to Or, S of organic compound 132 H Organic Compound 131 S A Singlet excitation transferred to The energy is transferred from the thermally activated delayed fluorescent substance (β) to the fluorophore via the energy transfer process. , guest material 133 S G Energy transfers to the guest material 1 in the singlet excited state. In this embodiment, the organic compound 132 is used as a host material. It will be explained as follows.

[0068] The singlet excited state of the organic compound 132 is converted into the triplet excited state of the guest material 133. Energy transfer occurs directly from the singlet ground state to the triplet excited state in the guest material133. Since the transition between the two is forbidden, it is unlikely to be the main energy transfer process. That is, as shown in the following general formula (G3) or (G4), the organic compound 132 Energy transfer from the singlet excited state to the singlet excited state of the guest material 133 is possible. do.

[0069] 1 H * + 1 A+ 1 G → 1 H+ 1 A+ 1 G * (G3)

[0070] 1 H * + 1 A+ 1 G → 1 H+ 1 A * + 1 G → 1 H+ 1 A+ 1 G * (G4)

[0071] In general formula (G3) or (G4), 1 H * , 1 A * , and 1 G * are available respectively. represents the singlet excited states of the organic compound 132, the organic compound 131, and the guest material 133; 1 H, 1 A, and 1 G represents organic compound 132, organic compound 131, and guest material, respectively. represents the singlet ground state of 133.

[0072] On the other hand, when an excited state of organic compound 132 is generated and it is a triplet excited state, Compound 132 T H is the T of organic compound 131 AHigher, S of organic compound 131 A But, Stock material 133 S G When the temperature is higher than 1000 ℃, fluorescence emission is obtained through the following process.

[0073] First, the T of organic compound 132 H From the organic compound 131 T A Energy transfers to.

[0074] The subsequent process is the energy transfer process from the thermally activated delayed fluorescent substance mentioned above (β). As explained in the previous section, the reverse intersystem crossing ( Route A1) to obtain S of organic compound 131 A From guest material 133S G Energy The guest material 133 is transferred and placed in a singlet excited state, and fluorescence is emitted from the guest material 133.

[0075] That is, the above-mentioned energy transfer process is represented by the following general formula (G5).

[0076] 3 H * + 1 A+ 1 G → 1 H+ 3 A * + 1 G → (reverse intersystem crossing) → 1 H+ 1 A * + 1 G → 1 H+ 1 A+ 1 G * (G5)

[0077] In general formula (G5), 3 H * and 3 A * are organic compounds 132 and organic compounds 133, respectively. represents the triplet excited state of organic compound 131,1 A * , and 1 G * are the organic compounds 1 31 and the singlet excited state of the guest material 133, 1 H, 1 A, and 1 G is represents the singlet ground state of organic compound 132, organic compound 131, and guest material 133. .

[0078] As shown in general formula (G5), the triplet excited state ( 3 H * ) from organic The triplet excited state of compound 131 ( 3 A * ) is produced, and then rapidly undergoes reverse intersystem crossing to form The singlet excited state of organic compound 131 ( 1 A * ) is generated, and then the guest material 133 Singlet excited state ( 1 G * ) energy transfers to

[0079] All energy transfer processes mentioned above in the (γ) energy transfer process from the host material If this occurs efficiently, the triplet excitation energy and singlet excitation energy of the organic compound 132 Both the 133 and 133 efficiently enter the singlet excited state ( 1 G * ), so This allows light to be emitted from the insulating material 133.

[0080] However, the singlet excited state of the organic compound 132 is converted to the singlet excited state of the guest material 133. Before the excitation energy is transferred to the ion-excitation state, the organic compound 132 converts the excitation energy into light or When the photon is released as heat and deactivated, the luminous efficiency decreases. In the organic compound 131, the reverse intersystem transition from the triplet excited state to the singlet excited state is If the efficiency of the intersecting route A1 process decreases, the luminous efficiency will also decrease. In particular, the T H However, the T of organic compound 131 A If it is lower than Compound 132 T H From organic compound 131 T A The energy transfer process to Therefore, reverse intersystem crossing does not occur in the organic compound 131, and the singlet excitation of the guest material 133 is Therefore, the efficiency of generating the excited state of organic compound 132 is reduced. H is organic compound 131 T A It is preferable that it is higher than

[0081] In addition, as shown in Route E3 of FIG. 2(C), T H From guest material 133T G When excitation energy is transferred to the Therefore, the route E3 in Figure 2(C) shows that the guest material 13 has fewer energy transfer processes. The generation efficiency of the triplet excited state of 3 can be reduced, and thermal deactivation can be reduced. For this purpose, the weight ratio of the organic compound 132 to the guest material 133 is preferably It is preferable that the weight ratio of the organic compound 132 and the guest material 133 is low. The weight ratio of the organic compound 132 to the guest material 133 is preferably 1:0. The ratio is preferably 1:0.001 to 1:0.05, more preferably 1:0.001 to 1:0.01. do.

[0082] As described above, in the energy transfer process from the host material (γ), the excitation energy A part of the energy is converted into the fluorescent emission of the guest material 133, but the route E2 and Thermal deactivation by processes E1 and E2 may occur. (β) rather than the energy transfer process in the guest material and (α) the direct recombination process in the guest material. The higher the rate of energy transfer from the thermally activated delayed fluorescent material, the higher the energy transfer rate in the light-emitting layer 120. This reduces the generation efficiency of triplet excited states, which is due to the reduction in thermal deactivation. This is preferable because it is possible to increase the luminous efficiency of the light emitting element 150. (β) Thermal Activity To increase the rate of energy transfer from the thermally activated delayed fluorescence, It is important that carrier recombination occurs in the organic compound 131, which is the substrate.

[0083] <Carrier recombination> In order for carrier recombination to occur in organic compound 131, organic compound 131 and The relationship between the energy levels of organic compounds 132 is important. In particular, the highest occupied molecular orbital (H Highest Occupied Molecular Orbital (HOMO) Lowest Unoccupied Molecular Orbital (Lowest Unoccupied Molecular Orbital) The relationship between the energy levels of the ionic liquid and the ionic liquid (also called LUMO or RBITAL), or the oxidation potential and reduction potential The relationship with the electric potential is important.

[0084] When carriers are injected from the pair of electrodes into the EL layer 100 and reach the light-emitting layer 120, Carriers are injected into the material that makes up 20. At this time, holes are injected into the more stable HOMO. Therefore, the electrons are easily transferred to the more stable LUMO. In order for carrier recombination to occur in the organic compound 131, the HOMO of the organic compound 131 must be , which has an energy level higher than the HOMO of organic compound 132, and the LUM of organic compound 131 It is important that O has an energy level below the LUMO of the organic compound 132. Alternatively, the oxidation potential of organic compound 131 is equal to or lower than the oxidation potential of organic compound 132. It is important that the reduction potential of the compound 131 is equal to or higher than the reduction potential of the organic compound 132 .

[0085] In addition, by adopting the above-mentioned configuration, excitation between the organic compound 131 and the organic compound 132 can be prevented. A structure that makes it difficult to form a complex can be achieved.

[0086] Furthermore, when molecules of the organic compound 131 are adjacent to each other in the light-emitting layer 120, carriers are generated. In this case, the organic compound 131 can move easily between molecules. For example, carriers may be more likely to move to the hole transport layer 112 and the electron transport layer 118. Therefore, recombination of carriers occurs in the organic compound 131 in the light-emitting layer 120. To achieve this, the weight ratio of organic compound 132 to organic compound 131 must be The lower the ratio, the better. In order to suppress the energy transfer between organic compound 132 and organic compound 131, The weight ratio of the organic compound 131 is preferably low. When molecules of the organic compound 131 and the organic compound 133 are adjacent to each other, the triplet excited state of the organic compound 131 is converted into guest molecules. There is a possibility of energy transfer to the triplet excited state of the cation material 133. In order to suppress the energy transfer, the weight ratio of organic compound 132 to organic compound 131 is It is preferable that the weight ratio of the organic compound 131 is low. The weight ratio of organic compound 132 to organic compound 131 (organic compound 132:organic compound 131) is 1:0.05 or A ratio of 1:0.5 is preferred.

[0087] <3. Energy transfer mechanism> Next, the organic compound 131 or the organic compound 132 is separated from the guest material 133. Explain the factors that govern the energy transfer process between molecules. Mechanism of energy transfer between molecules The Förster mechanism (dipole-dipole interaction) and the Dexter mechanism (electron exchange Two mechanisms have been proposed: the interaction of organic compound 131 with a guest The energy transfer process between molecules of the material 133 is explained. The same applies to the energy transfer process between the molecules of the guest material 133 and the guest material 133.

[0088] <Förster mechanism> In the Förster mechanism, direct contact between molecules is not required for energy transfer. Energy transfer occurs through the resonance phenomenon of dipole vibration between the compound 131 and the guest material 133. The organic compound 131 transfers energy to the guest material 133 through the resonance phenomenon of the dipole vibration. The excited organic compound 131 returns to the ground state, and the guest material 13 3 becomes excited. The rate constant of the Förster mechanism is k h*→g is shown in formula (1) .

[0089]

number

[0090] In formula (1), ν represents the frequency, and f' h (ν) is the standard for organic compound 131 The emission spectrum (or the fluorescence spectrum when discussing energy transfer from the singlet excited state) spectrum, and phosphorescence spectrum when discussing energy transfer from triplet excited states), ε g (ν) represents the molar extinction coefficient of the guest material 133, N represents Avogadro's number, and n represents the refractive index of the medium, and R represents the intermolecular distance between the organic compound 131 and the guest material 133. where τ represents the measured lifetime of the excited state (fluorescence lifetime or phosphorescence lifetime), and c represents the speed of light. , φ is the luminescence quantum yield (fluorescence quantum yield when discussing energy transfer from the singlet excited state) represents the phosphorescence quantum yield when discussing energy transfer from the triplet excited state, and K 2 teeth , a coefficient (between 0 and 1) that represents the orientation of the transition dipole moment of the organic compound 131 and the guest material 133 In the case of random orientation, K 2 =2 / 3.

[0091] Dexter Mechanism In the Dexter mechanism, an organic compound 131 and a guest material 133 are bonded together, resulting in orbital overlap. The electrons of the excited organic compound 131 approach the effective distance and the electrons of the guest material 13 in the ground state are Energy transfer occurs through the exchange of electrons with 3. The rate constant for the Dexter mechanism is k h*→g is shown in equation (2).

[0092]

number

[0093] In equation (2), h is Planck's constant, and K is a constant with the dimension of energy. where ν represents the frequency and f' h (ν) is the normalized emission spectrum of organic compound 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 133, L represents the effective molecular radius, R represents the intermolecular distance between the organic compound 131 and the guest material 133 .

[0094] Here, the energy transfer efficiency φ from the organic compound 131 to the guest material 133 ET is a number It is expressed by equation (3). r The emission process of organic compound 131 (energy from the singlet excited state) When discussing energy transfer, we use fluorescence; when discussing energy transfer from triplet excited states, we use phosphorus. represents the rate constant of photon transport, k n is the non-radiative process (thermal deactivation and intersystem crossing) of organic compound 131. represents the rate constant, and τ represents the measured excited state lifetime of the organic compound 131.

[0095]

number

[0096] From equation (3), the energy transfer efficiency φ ET To increase the energy transfer rate, Degree constant k h*→g By increasing the rate constant k r +k n (=1 / τ) is relatively You know the smaller the better.

[0097] <Concept for enhancing energy transfer> In both of the energy transfer processes of the general formula (G1) and the general formula (G2), Singlet excited state of organic compound 131 ( 1 A *) to the singlet excited state of guest material 133 ( 1 G * ), the Förster mechanism (Equation (1)) and the dextro- Energy transfer occurs via both the hydroxylase mechanism (Equation (2)) and the hydroxylase mechanism (Equation (3)).

[0098] First, consider the energy transfer via the Förster mechanism. From equations (1) and (3), Eliminating τ, the energy transfer efficiency φ ET is the quantum yield φ (energy from the singlet excited state) Since we are discussing energy transfer, it can be said that a higher fluorescence quantum yield is better. Another important factor is the emission spectrum of organic compound 131 (from the singlet excited state). Since we are discussing the energy transfer from the guest material, the fluorescence spectrum and the absorption spectrum of the guest material are The absorption corresponding to the transition from the singlet ground state to the singlet excited state is large. It is preferable that the molar absorption coefficient of the guest material 133 is also high. The emission spectrum of the organic compound 131 and the absorption spectrum of the guest material 133 appearing at the longest wavelength are shown in Fig. This means that it overlaps with collection.

[0099] Next, consider the energy transfer via the Dexter mechanism. According to equation (2), the rate constant is k h*→g To increase the emission spectrum of organic compound 131 (from the singlet excited state), Since energy transfer is discussed, the fluorescence spectrum and the absorption spectrum of the guest material 133 (absorption corresponding to the transition from the singlet ground state to the singlet excited state) I know it's a good thing.

[0100] From the above, the optimization of the energy transfer efficiency is based on the emission spectrum of organic compound 131. This is realized by overlapping the absorption band appearing on the longest wavelength side of the guest material 133. .

[0101] Therefore, one embodiment of the present invention is to provide an energy source that can efficiently transfer energy to the guest material 133. The present invention provides a light-emitting element using an organic compound 131 that functions as an electron donor. Since the organic compound 131 is a thermally activated delayed fluorescent material, it has a singlet excited energy level and a triplet excited energy level. Specifically, organic compound 1 The difference between the singlet and triplet excited energy levels of 31 is greater than 0 eV. By adopting the above-mentioned configuration, the triplet excitation of the organic compound 131 is preferably 0.2 eV or less. The transition from the excited state to the singlet excited state (reverse intersystem crossing) is likely to occur. Furthermore, the efficiency of generating the singlet excited state of the organic compound 131 can be increased. The singlet excited state of the guest material 133, which acts as an energy acceptor, is In order to facilitate the energy transfer to It is preferable that the absorption band of the guest material 133 overlaps with the absorption band that appears on the longest wavelength side. Therefore, the efficiency of generating the singlet excited state of the guest material 133 can be increased.

[0102] In addition, in the light-emitting element 150 of one embodiment of the present invention, the HOMO of the organic compound 131 is The LUMO of organic compound 131 is higher than the HOMO of organic compound 132. having an energy level below the LUMO of organic compound 132, or organic compound 131 The oxidation potential of organic compound 132 is equal to or less than the oxidation potential of organic compound 131, and the reduction potential of organic compound 131 is Since the potential is equal to or higher than the reduction potential of the organic compound 132, the carriers injected into the EL layer 100 are efficiently Therefore, there is little thermal deactivation and light emission Efficiency can be improved.

[0103] <4.Materials> Next, components of a light-emitting element according to one embodiment of the present invention will be described in detail below.

[0104] <Light-emitting layer> In the light-emitting layer 120, the organic compound 131 is composed of one kind of material. In addition to the compound 131, other compounds having similar functions are further contained in the light-emitting layer 120. For example, if the organic compound 131 is composed of one kind of material, the following materials can be used: You can be there.

[0105] First, there are fullerene and its derivatives, acridine derivatives such as proflavine, and eosin. In addition, magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn) Metal-containing polymers including platinum (Pt), indium (In), or palladium (Pd) Examples of the metal-containing porphyrin include porphyrins represented by the following structural formula: The protoporphyrin-tin fluoride complex (SnF2(Proto IX)) Hematoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-fluoride complex (SnF2(Meso IX)), Tin fluoride complex (SnF2(Hemato IX)), coproporphyrin tetramethyl ether SnF2(Copro III-4Me) Porphyrin-tin fluoride complex (SnF2(OEP)), etioporphyrin-tin fluoride Complex (SnF2(Etio I)), Octaethylporphyrin-Platinum Chloride Complex (PtC l2OEP) etc.

[0106] [ka]

[0107] The organic compound 131 is 2-(biphenyl-4-yl)-2-phenyl-4-methyl-2 ... 12-phenylindolo[2,3-a]carbazol-11-yl )-1,3,5-triazine (abbreviation: PIC-TRZ), 2-{4-[3-(N-phenyl (9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4 ,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 2-[4-( 10H-phenoxazin-10-yl)phenyl]-4,6-diphenyl-1,3,5- Triazine (abbreviation: PXZ-TRZ), 3-[4-(5-phenyl-5,10-dihydro (Phenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (Abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl )-9H-xanthen-9-one (abbreviation: ACRXTN), bis[4-(9,9-dimethyl (9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), 10-phenyl-10H,10'H-spiro[acridine-9,9'-anthracene]- π-electron rich heteroaromatic rings and π-electron deficient heteroaromatic rings such as 10'-one (abbreviation: ACRSA) A heterocyclic compound having an aromatic ring can also be used. The heterocyclic compound is a π-electron-rich heterocyclic compound. Because it has a heteroaromatic ring and a π-electron-deficient heteroaromatic ring, it has high electron transport properties and hole transport properties. Among these, among the skeletons having a π-electron deficient heteroaromatic ring, a diazine skeleton (pyrimidine) is preferred. The azine, pyrazine, pyridazine, or triazine skeleton is stable and reliable. Furthermore, among the skeletons having a π-electron-rich heteroaromatic ring, acyl groups are particularly preferred. Lysine skeleton, phenoxazine skeleton, or 3-(9-phenyl-9H-carbazole-3 The (-yl)-9H-carbazole skeleton is stable and reliable, so It is particularly preferable that the π-electron-rich complex has one or more of the above-mentioned structures. A substance in which an aromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded is called a π-electron-rich heteroaromatic ring. Both the donor and the acceptor properties of the π-electron-deficient heteroaromatic ring are strong, and the singlet excited state level This is particularly preferable because the difference between the energy levels of the triplet excited state and the excited state of the triplet is small.

[0108] [ka]

[0109] In the light-emitting layer 120, the organic compound 132 may be, for example, the following compound: The organic compound 132 functions as a host material in the light-emitting layer 120. Therefore, there are two types of skeletons: one that easily receives electrons (one that has electron transport properties) and one that easily receives holes. It is preferable that the polymer has either one or both of a skeleton (a skeleton having hole transport properties) and a structure (a skeleton having hole transport properties). stomach.

[0110] Compounds with a skeleton that easily accepts electrons (skeleton with electron transport properties) include π electron Compounds having a deficient heteroaromatic skeleton, metal complexes, etc. can be used. , bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeB q2), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum zinc(III) (abbreviation: BAlq), bis(8-quinolinolato)zinc(II) (abbreviation: Zn q), bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnP BO), bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnB TZ) and 2-(4-biphenylyl)-5-(4-tert-butylphenyl)- 3-(4-biphenylyl)-1,3,4-oxadiazole (abbreviation: PBD), 4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation Name: TAZ), 9-[4-(4,5-diphenyl-4H-1,2,4-triazole-3 -yl)phenyl]-9H-carbazole (abbreviation: CzTAZ1), 1,3-bis[5- (p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene OXD-7, 9-[4-(5-phenyl-1,3,4-oxadiazole- 2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 2,2',2''-( 1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole)( Abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl mDBTBIm-II and other azole skeletons Heterocyclic compounds having 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzoyl 2-[3'-(dibenzo[f,h]quinoxaline] (abbreviation: 2mDBTPDBq-II) [4-( ... Name: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)bis(2-methyl-2-propanol) phenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[3-(3,9'-bi-9H-carbazol-9-yl)phenyl]dibenzo[f, h]quinoxaline (abbreviation: 2mCzCzPDBq), 4,6-bis[3-(9H-carba 4,6-biphenyl-9-yl)pyrimidine (abbreviation: 4,6mCzP2Pm), 4,6mPnP2 Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4 Heterocyclic compounds with diazine skeletons such as PCCzP Heterocyclic compounds with triazine skeletons such as Tzn and 3,5-bis[3-(9H-cal (35DCzPPy) 1,3,5-trimethylbenzol-9-ylphenyl]pyridine (abbreviation: 35DCzPPy) Pyridine skeleton such as thi[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB) Among the heterocyclic compounds mentioned above, diazines (pyridyl compounds) are Heterocyclic compounds having a pyridine skeleton (pyridine, pyrazine, pyridazine) or a pyridine skeleton are stable. Moreover, heterocyclic compounds having such a skeleton have electron transport properties. This also contributes to reducing the driving voltage.

[0111] Compounds with a skeleton that easily accepts holes (skeleton with hole transport properties) include π-electron Compounds having an excess of heteroaromatic skeletons or aromatic amine skeletons can be preferably used. Specifically, 2-[N-(9-phenylcarbazol-3-yl)-N-phenyl] 4,4'-bis[N -(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB), N,N'-biphenyl (3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4 '-diamine (abbreviation: TPD), 4,4'-bis[N-(spiro-9,9'-bifluorene 4-phenyl- 4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP) ), 4-phenyl-3'-(9-phenylfluoren-9-yl)triphenylamine ( abbreviation: mBPAFLP), 4-phenyl-4'-(9-phenyl-9H-carbazole- 3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4' '-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PC BBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazole- 3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl) -4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation : PCBNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H -carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl] Spiro-9,9'-bifluoren-2-amine (abbreviation: PCBASF), N-(1,1' -biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl] )phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF ), and 1,3-bis(N-carbazolyl)benzene mCP, 4,4'-di(N-carbazolyl)biphenyl (CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: Cz TP), 3,6-di(9H-carbazol-9-yl)-9-phenyl-9H-carbazo (abbreviation: PhCzGI), 2,8-di(9H-carbazol-9-yl)-dibenzo Thiophene (abbreviation: Cz2DBT), 9-phenyl-9H-3-(9-phenyl-9H- Carbazol-3-yl)carbazole (abbreviation: PCCP) and other compounds having a carbazole skeleton. and 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzo thiophene) (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl) (9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFL P-III), 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]- Thiophene skeleton such as 6-phenyldibenzothiophene (abbreviation: DBTFLP-IV) and compounds having 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzoyl) Zofran) (abbreviation: DBF3P-II), 4-{3-[3-(9-phenyl-9H-fluro[ dibenzofuran (abbreviated as mmDBFFLBi- Among the above, compounds having a furan skeleton, such as thiophene, ... Compounds with olefin, fluorene, and pyrrole skeletons are stable and reliable. In addition, it has a high hole transporting property and contributes to reducing the driving voltage, which is preferable.

[0112] Among the above-mentioned compounds, a pyridine skeleton is particularly preferred as a π-electron-deficient heteroaromatic skeleton. Or it has a diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton) and π electrons Excessive heteroaromatic skeletons include furan skeleton, thiophene skeleton, fluorene skeleton, and pyrrole skeleton. Compounds having one or more selected from the above have high carrier transport properties. This contributes to reducing the driving voltage. In addition, compounds having this skeleton have good reliability. The pyrrole skeleton is preferably an indole skeleton, a carbazole skeleton, or A 3-(9H-carbazol-9-yl)-9H-carbazole skeleton is particularly preferred.

[0113] The organic compounds 131 and 132 are not limited to the compounds described above. The HOMO of organic compound 131 has an energy level higher than the HOMO of organic compound 132. The LUMO of organic compound 131 is at an energy level lower than the LUMO of organic compound 132. or the oxidation potential of organic compound 131 is The oxidation potential of organic compound 131 is equal to or less than the reduction potential of organic compound 132. The combination is one that can transport carriers, and other materials may also be used. In addition, a thermally activated delayed fluorescent material may be used as the organic compound 132 .

[0114] Examples of compounds that can be used for the above organic compound 131 and organic compound 132 are as follows: The results of measuring the HOMO and LUMO energy levels in each thin film state are shown below. 1. The oxidation potential and reduction potential in the solution state were measured and estimated from the results. The HOMO and LUMO energy levels are shown in Table 2. The results of the measurement of the electromotive force levels are shown in Table 3. The structures and abbreviations of the compounds are as follows: show.

[0115] [ka]

[0116] [Table 1]

[0117] [Table 2]

[0118] [Table 3]

[0119] The HOMO energy level in the thin film state varies depending on the ionization potential of each compound. The ionization potential was measured in air using photoelectron spectroscopy (Riken Keiki, AC-3). The absorption spectra of each compound in the thin film state were calculated by converting the negative values into negative values. The absorption edge is calculated from the Tauc plot assuming a direct transition. The optical band gap of the ZnO-doped SiO2-based ... From the HOMO energy level obtained above, the LUMO energy level in the thin film state was calculated. I put it out.

[0120] In addition, the electrochemical properties (oxidation reaction properties, reduction reaction properties) of each compound in solution were measured. The measurements were carried out by cyclic voltammetry (CV). Analyzer (manufactured by BAS Corporation, model number: ALS model 600A or 600C) In the measurement, the potential of the working electrode relative to the reference electrode was changed within an appropriate range to measure the concentration of each acid. The oxidation peak potential and reduction peak potential were obtained. From this value and the obtained peak potential, The HOMO and LUMO energy levels of the compounds were calculated.

[0121] The triplet excitation energy level was measured by measuring the phosphorescence of each compound. The PL microscope LabRAM HR-PL (Horiba, Ltd.) was used, and the measurement temperature was 10 K, a He-Cd laser (325 nm) was used as the excitation light, and a CCD detector was used as the detector. The peak at the shortest wavelength in the phosphorescence spectrum obtained from the measurement was used. The excitation energy levels were calculated.

[0122] As an example, in Tables 1 and 2, the HOMO of organic compound 131 is The LUMO of organic compound 131 is higher than that of organic compound 1. Use compounds with a combination of 32 LUMO or lower energy levels, or The oxidation potential of organic compound 131 is equal to or lower than the oxidation potential of organic compound 132, and the oxidation potential of organic compound 132 is equal to or lower than the oxidation potential of organic compound 131. The reduction potential of the organic compound 131 is higher than that of the organic compound 132. By this, the carriers injected into the EL layer 100 are efficiently transported in the organic compound 131. Since recombination can be easily achieved, a light-emitting element with high luminous efficiency can be provided.

[0123] As an example shown in Table 3, the triplet excited energy level of organic compound 132 is Using compounds with a combination that results in a triplet excited energy level higher than that of organic compound 131, By this, the triplet excited energy level of organic compound 132 is converted to the triplet excited energy level of organic compound 131. Therefore, the above-mentioned (γ) phosphite is easily transferred to the excited energy level. This facilitates the energy transfer process from the ion exchange material, thereby providing a light-emitting device with high luminous efficiency. It is possible.

[0124] In the light-emitting layer 120, the guest material 133 (fluorescent material) is not particularly limited, but may be: Anthracene derivatives, tetracene derivatives, chrysene derivatives, phenanthrene derivatives, pyrene derivatives derivatives, perylene derivatives, stilbene derivatives, acridone derivatives, coumarin derivatives, Phenoxazine derivatives, phenothiazine derivatives, etc. are preferred, and the following materials are used, for example: It is possible.

[0125] 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 (9-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-(9H-carbazol-9-yl)phenyl] -N,N'-diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-( 9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenyl Nylamine (abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4'-(9 ,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H -Carbazole-3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetradecanoic acid Tri(tert-butyl)perylene (TBP), 4-(10-phenyl-9-anthracene) (aryl)-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-phenyl diamine] (abbreviation: DPABPA), N,9-diphenyl-N-[4-(9,10- Diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: 2 PCAPPA), 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 3 0, N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-chlor 2PCAPA, N-[9,10-bis(1,1'-biphenyl)] [phenyl-2-yl]-2-anthryl]-N,9-diphenyl-9H-carbazole-3 -amine (abbreviation: 2PCABPhA), 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-2-yl)-N-[4-(9H-carbazole -9-yl)phenyl]-N-phenylanthracen-2-amine (abbreviation: 2YGABP hA), N,N,9-triphenylanthracene-9-amine (abbreviation: DPhAPhA) , Coumarin 6, Coumarin 545T, N,N'-diphenylquinacridone (abbreviation: DPQd ), 5,6,11,12-tetraphenylnaphthacene (common name: rubrene), 5,12- Bis(1,1'-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: B PT), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl -4H-pyran-4-ylidene)propanedinitrile (abbreviation: DCM1), 2-{2-methyl- 6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolinyl] {4H-pyran-4-ylidene}propanedinitrile (abbreviated :DCM2), N,N,N',N'-tetrakis(4-methylphenyl)tetracene-5 ,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N',N '-Tetrakis(4-methylphenyl)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[i j]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinite 2-(2-tert-butyl-6-[2-(1,1,7,7 -Tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizidine 4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB), 2-(2,6-bis{2-[4-(dimethylamino)phenyl]ethenyl }-4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDCM), 2-{ 2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7- Tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H- Pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJ™), 5,10,1 5,20-tetraphenylbisbenzo[5,6]indeno[1,2,3-cd:1',2 ',3'-lm]perylene, etc.

[0126] The guest material 133 is not limited to the above materials. The emission of the donor organic compound 131 (thermally activated delayed fluorescence) is The longest wavelength absorption band in the absorption spectrum of the luminescent material of the guest material 133 ( The absorption corresponding to the transition from the singlet ground state to the singlet excited state of the guest material 133 overlaps with that of the Any other material may be used as long as it satisfies the above requirements.

[0127] The light-emitting layer 120 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 rabbet printing.

[0128] Next, other details of the configuration of the light emitting element 150 shown in FIG. 1(A) will be described below. .

[0129] <Pair of electrodes> The electrode 101 and the electrode 102 have the function of injecting holes and electrons into the light-emitting layer 120. The electrodes 101 and 102 are made of metals, alloys, conductive compounds, and mixtures or laminates thereof. The metal can be formed by using aluminum, and other materials. transition metals such as silver, tungsten, chromium, molybdenum, copper, and titanium; lithium and cesium Alkali metals such as sodium, and Group 2 metals such as calcium and magnesium can be used. A rare earth metal such as ytterbium (Yb) may be used as the transition metal. As the material, an alloy containing the above metals can be used, for example, MgAg, AlLi, etc. As the conductive compound, indium oxide-tin oxide (InTinOxide) Examples of conductive compounds include inorganic compounds such as graphene. Carbon-based materials may also be used. As mentioned above, by laminating multiple layers of these materials, Alternatively, one or both of the electrodes 101 and 102 may be formed using a metal oxide film.

[0130] The light emitted from the light-emitting layer 120 is emitted from one or both of the electrodes 101 and 102. Therefore, at least one of the electrodes 101 and 102 is visible. When a material with low light transmittance, such as a metal or alloy, is used for the electrode that extracts light, In this case, the electrode 1 is formed to a thickness that is thick enough to transmit visible light (for example, a thickness of 1 nm to 10 nm). Either or both of the electrode 101 and the electrode 102 may be formed.

[0131] <Hole injection layer> The hole injection layer 111 reduces the hole injection barrier from the electrode 101, thereby facilitating hole injection. For example, transition metal oxides, phthalocyanine derivatives, or aromatic alkyl acrylates have the function of promoting the formation of hydroxyl groups. The transition metal oxides are formed by molybdenum oxide and vanadium oxide. oxide, ruthenium oxide, tungsten oxide, manganese oxide, etc. Examples of phthalocyanine derivatives include phthalocyanine and metal phthalocyanine. Examples of aromatic amines include benzidine derivatives and phenylenediamine derivatives. Polymer compounds such as polythiophene and polyaniline can also be used. Poly(ethylenedioxythiophene) / poly(styrenesulfonyl)thiophene, a cross-linked polythiophene sulfonic acid) are typical examples.

[0132] The hole injection layer 111 is made of a compound material including a hole transporting material and a material that exhibits electron accepting properties. Alternatively, a layer containing a material exhibiting electron accepting properties and a layer containing a material exhibiting electron accepting properties may be used. A stack of layers containing hole transport materials may also be used. It is possible to exchange charges in the presence of a magnetic field. Materials that exhibit electron-accepting properties include quinodimethane. Organic acceptors such as benzophenone derivatives, chloranil derivatives, 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 compounds have electron-withdrawing groups (halogen groups or cyano groups), such as hydroxybenzoates (HAT-CN). In addition, transition metal oxides, for example, oxides of metals from Groups 4 to 8, can be used. In general, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, These include tungsten oxide, manganese oxide, and rhenium oxide. Among these, it is preferred because it is stable, has low hygroscopicity, and is easy to handle.

[0133] As the hole transporting material, a material having a higher hole transporting property than an electron transporting property can be used. x10 -6 cm 2 It is preferable that the material has a hole mobility of 1 / Vs or more. The compounds are prepared using aromatic amines, carbazole derivatives, aromatic hydrocarbons, stilbene derivatives, etc. In addition, the organic compound 132 having a skeleton that easily accepts holes can be used. The hole transporting material may be a polymer compound. stomach.

[0134] <Hole transport layer> The hole transport layer 112 is a layer containing a hole transport material. The hole transport layer 112 can be formed by injecting the hole into the hole injection layer 111. The hole injection layer 111 has a function of transporting the holes to the light emitting layer 120. It is preferable that the HOMO energy level is at or close to the HOMO energy level.

[0135] ≪Electron transport layer≫ The electron transport layer 118 transports electrons injected from the electrode 102 through the electron injection layer 119 to the light emitting layer 104. As an electron transporting material, it has a higher transporting ability of electrons than holes. A wide range of materials can be used, and the -6 cm 2 Materials with electron mobility of ≥ 1000 V Specifically, quinoline ligands, benzoquinoline ligands, oxazoline ligands, Metal complexes with thiazole or thiazole ligands, oxadiazole derivatives, triazole derivatives, Examples include azole derivatives, phenanthroline derivatives, pyridine derivatives, and bipyridine derivatives. In addition, the compounds having a skeleton that easily accepts electrons, which are exemplified as organic compounds 132, Things can be used.

[0136] ≪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 electron transport material and the corresponding electron transport material can be used. 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.

[0137] The hole injection layer 111, the hole transport layer 112, the electron transport layer 118, and the electron injection layer 119 are The layer 119 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 rabbet printing.

[0138] Also, the hole injection layer 111, the hole transport layer 112, the light emitting layer 120, the electron transport layer 118, and The electron injection layer 119 may contain, in addition to the above-mentioned materials, inorganic compounds or polymer compounds (oligomers , dendrimers, polymers, etc.) may also be used.

[0139] <Substrate> The light emitting element 150 may be fabricated on a substrate made of glass, plastic, or the like. The order of fabrication on the substrate can be from the electrode 101 side to the electrode 102 side. They may be laminated in order.

[0140] The substrate on which the light emitting element 150 can be formed is, for example, glass, quartz, or plastic. A flexible substrate may be used. It is a (flexible) substrate that can be used for example, polycarbonate, polyamide Examples of the substrate include plastic substrates made of inorganic films and inorganic vapor deposition films. In the manufacturing process of the light emitting element and the optical element, Any other device may be used as long as it functions as a light emitting element. Anything that has the function of protecting the element may be used.

[0141] For example, various substrates can be used to form the light emitting device 150. The types of substrates include: The substrate is not limited to a specific one. An example of the substrate is a semiconductor substrate (e.g., a single crystal crystal substrate or silicon substrate), SOI substrate, glass substrate, quartz substrate, plastic substrate, gold Metal substrate, stainless steel substrate, substrate with stainless steel foil, tungsten Tungsten substrate, substrate with tungsten foil, flexible substrate, laminated film, fiber Examples of glass substrates include paper or substrate films containing barium-based materials. Examples include borosilicate glass, aluminoborosilicate glass, and soda-lime glass. Examples of flexible substrates, laminated films, and base films include the following: For example, polyethylene terephthalate (PET), polyethylene naphthalate (P EN), polyethersulfone (PES), polytetrafluoroethylene (PTFE) Plastics such as acrylic are also examples of plastics. Alternatively, for example, polypropylene, polyester, polyvinyl fluoride, or poly Examples include polyamide, polyimide, aramid, and vinyl chloride. Examples include epoxy, inorganic vapor deposition film, and paper.

[0142] Alternatively, 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 device is completed, it is separated from the substrate and used to transfer it to another substrate. In this case, the light-emitting element can be transferred onto a substrate having poor heat resistance or a flexible substrate. The peeling layer may have a laminated structure of inorganic films, such as a tungsten film and a silicon oxide film. or a structure in which a resin film such as polyimide is formed on a substrate, etc., can be used.

[0143] 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 substrates mentioned above, cellophane substrates, stone substrates, wood substrates, fabric substrates (natural fibers (silk, cotton, Hemp), synthetic fibers (nylon, polyurethane, polyester) or regenerated fibers (acetate (including cellulose, cupro, rayon, recycled polyester, etc.), leather substrate, rubber substrate, etc. By using these substrates, it is possible to produce light emitting elements that are durable and highly heat resistant. The light emitting element may be a small, lightweight, or thin light emitting element.

[0144] Furthermore, for example, a field effect transistor (FET) is formed on the above-mentioned substrate, and the FET and The light emitting element 150 may be fabricated on the electrically connected electrodes. In this way, an active matrix display device that controls the driving of the light emitting element 150 can be fabricated.

[0145] Note that one embodiment of the present invention has been described in this embodiment. However, the present invention is not limited to these embodiments. For example, in one embodiment of the present invention, the HOMO of organic compound 131 is The LUMO of organic compound 131 is higher than that of organic compound 1. The oxidation potential of organic compound 131 is significant when the energy level of the LUMO of 32 is lower than that of the LUMO of 32. The oxidation potential of organic compound 132 is less than or equal to the reduction potential of organic compound 131. However, one embodiment of the present invention is not limited to this. In some cases, or depending on the situation, in one embodiment of the present invention, for example, organic compound 131 The HOMO of the organic compound 132 does not have to have an energy level higher than the HOMO of the organic compound 132. Alternatively, the LUMO of organic compound 131 is at an energy level lower than the LUMO of organic compound 132. Alternatively, the oxidation potential of the organic compound 131 may be equal to or smaller than the oxidation potential of the organic compound 132. Alternatively, the reduction potential of organic compound 131 may be lower than that of organic compound 132. Alternatively, for example, in one embodiment of the present invention, the organic compound 131 may have a potential higher than the original potential. In the above example, the substance exhibits thermally activated delayed fluorescence at room temperature. However, in some cases or depending on the situation, in one aspect of the present invention, For example, the organic compound 131 does not contain any substance other than a substance that exhibits thermally activated delayed fluorescence at room temperature. Alternatively, depending on the circumstances, in one aspect of the present invention, for example, For example, the organic compound 131 does not need to contain a substance that exhibits thermally activated delayed fluorescence at room temperature. Or, for example, in one embodiment of the present invention, the weight ratio of organic compound 132 to organic compound 131 is Although an example in which the weight ratio of the organic compound 131 is low is shown, one embodiment of the present invention is not limited to this. In some cases, or depending on the circumstances, in one aspect of the present invention, for example, organic The weight ratio of compound 132 to organic compound 131 is not low, even if the weight ratio of organic compound 131 is not low. good.

[0146] As described above, the structure shown in this embodiment mode can be used in appropriate combination with other embodiment modes. Cut.

[0147] (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 explained below with reference to FIGS.

[0148] <Configuration example of light-emitting element> FIG. 3A is a schematic cross-sectional view of a light-emitting element 450. FIG.

[0149] The light-emitting element 450 shown in FIG. 3A has a pair of electrodes (electrodes 401 and 402) between them. , a plurality of light-emitting units (in FIG. 3(A), light-emitting unit 441 and light-emitting unit 4 42). One light-emitting unit has a structure similar to that of the EL layer 100 shown in FIG. That is, the light emitting element 150 shown in FIG. 1 has one light emitting unit, and the light emitting element 450 The light-emitting element 450 has a plurality of light-emitting units. The following description will be given assuming that the electrode 401 functions as a cathode and the electrode 402 functions as a cathode. The configuration may be reversed.

[0150] In addition, in the light-emitting element 450 shown in FIG. 3A, the light-emitting unit 441 and the light-emitting unit The light-emitting units 441 and 442 are stacked, and a charge generating element is formed between the light-emitting units 441 and 442. The light emitting unit 441 and the light emitting unit 442 have the same configuration. For example, the light-emitting unit 441 may have the EL layer 100 shown in FIG. It is preferable to use a light-emitting layer containing a phosphorescent material as the light-emitting material in the light-emitting unit 442. .

[0151] That is, the light-emitting element 450 includes a light-emitting layer 443 and a light-emitting layer 444. The optical unit 441 includes a light-emitting layer 443, a hole injection layer 411, a hole transport layer 412, an electron The light-emitting unit 442 includes a light-emitting layer 413 and an electron-injecting layer 414. In addition to 44, a hole injection layer 415, a hole transport layer 416, an electron transport layer 417, and an electron injection layer It has 418.

[0152] The charge generation layer 445 contains a composite material of an organic material and a material exhibiting electron accepting properties. The composite material can be used for the hole-injection layer 111 shown in Embodiment 1. A composite material may be used. Examples of organic materials include aromatic amine compounds and carbazole compounds. , aromatic hydrocarbons, polymer compounds (oligomers, dendrimers, polymers, etc.), etc. As the organic material, a compound having a hole mobility of 1×10 -6 c m 2 However, it is preferable to use a material with a hole transport property higher than that of electron transport property. Other materials may be used as long as they have high electron-accepting properties. The composite material has excellent carrier injection and carrier transport properties, making it suitable for low-voltage operation and low-voltage operation. In addition, as in the light-emitting unit 442, the positive When the polar side surface is in contact with the charge generation layer 445, the charge generation layer 445 is in contact with the positive electrode of the light-emitting unit. It can also function as a hole injection layer or a hole transport layer, so the light-emitting unit The layer or the hole transport layer may not be provided.

[0153] The charge generation layer 445 includes a layer including a composite material of an organic material and a material exhibiting electron accepting properties, It may be formed as a laminated structure in which layers made of other materials are combined. For example, a layer including a composite material of an organic material and a material exhibiting electron accepting properties, and a layer including a composite material of an organic material and a material exhibiting electron donating properties; The layer may be formed by combining a layer containing one of the materials selected from the above and a material having high electron transporting properties. In addition, a layer including a composite material of an organic material and a material exhibiting electron accepting properties and a layer including a transparent conductive film and may be formed in combination.

[0154] The charge generating layer 445 sandwiched between the light emitting unit 441 and the light emitting unit 442 is When a voltage is applied between the electrode 401 and the electrode 402, electrons are injected into one of the light-emitting units, and the other For example, in FIG. 3(A), When a voltage is applied so that the potential of electrode 401 is higher than the potential of electrode 402, a charge is generated. The organic layer 445 injects electrons into the light-emitting unit 441 and holes into the light-emitting unit 442. do.

[0155] In addition, in FIG. 3A, a light-emitting element having two light-emitting units has been described. However, the same configuration can be applied to a light-emitting element in which three or more light-emitting units are stacked. As shown in the light emitting device 450, a plurality of light emitting units are electrically connected between a pair of electrodes. By separating the layers, high brightness light emission is possible while keeping the current density low. Furthermore, it is possible to realize a light emitting element with a longer life. can.

[0156] At least one of the multiple units has the EL layer 100 shown in FIG. By applying the above structure, a light-emitting element with high luminous efficiency can be provided.

[0157] The light-emitting layer 443 is made of an organic compound 421, an organic compound 422, and a guest material 423. The light-emitting layer 444 includes an organic compound 431, an organic compound 432, and a guest Material 433.

[0158] In this embodiment, the light-emitting layer 443 has the same structure as the light-emitting layer 120 shown in FIG. That is, the organic compound 421, the organic compound 422, and the gate electrode contained in the light-emitting layer 443 are The photoresist material 423 is a mixture of the organic compound 131, the organic compound 132, and the photoresist contained in the light-emitting layer 120. The guest material 433 in the light-emitting layer 444 corresponds to the guest material 133. The phosphorescent material will be described below. 415, hole transport layers 412 and 416, electron transport layers 413 and 417, and electron injection layer 414 and 418 are the electrode 101, the electrode 102, the hole-injection layer 111, the hole These correspond to the transport layer 112, the electron transport layer 118, and the electron injection layer 119, respectively. In this embodiment, a detailed description thereof will be omitted.

[0159] <Light Emitting Mechanism of the Light Emitting Layer 443> The light emitting mechanism of the light emitting layer 443 is the same as the light emitting mechanism of the light emitting layer 120 shown in FIG.

[0160] <Light Emitting Mechanism of the Light Emitting Layer 444> Next, the light emitting mechanism of the light emitting layer 444 will be described below.

[0161] The organic compound 431 and the organic compound 432 in the light-emitting layer 444 form an exciplex. Here, the organic compound 431 is used as a host material, and the organic compound 432 is used as an assist material. It will be referred to and explained as follows.

[0162] The combination of the organic compound 431 and the organic compound 432 forms an exciplex in the light-emitting layer 444. Any combination that can form a body is acceptable, but one of the materials must have hole transport properties. It is more preferable that one of the first and second layers is a material having electron transport properties.

[0163] The organic compound 431, the organic compound 432, and the guest material 433 in the light-emitting layer 444 The correlation of the energy levels is shown in Figure 3(B). The notations and symbols in Figure 3(B) are , as follows: ·Host(431): Host material (organic compound 431) ·Assist(432): Assist material (organic compound 432) Guest (433): Guest material 433 (phosphorescent material) ·S PH : The lowest singlet excited state of the host material (organic compound 431) T PH : The lowest triplet excited state of the host material (organic compound 431) T PG : The lowest level of the triplet excited state of guest material 433 (phosphorescent material) ·S PE : The lowest level of the singlet excited state of an exciplex T PE : The lowest level of the triplet excited state of an exciplex

[0164] Singlet excited state of the exciplex formed by organic compound 431 and organic compound 432 The lowest level of (S PE ) and the lowest triplet excited state of the exciplex (T PE ) are mutual (See route E7 in Figure 3(B)).

[0165] And the S of the exciplex PE and T PE The energy of both the guest material 433 (phosphorescent material The lowest triplet excited state (T PG ) to obtain luminescence (Figure 3(B )See route E8).

[0166] The above-described processes of Route E7 and Route E8 are referred to as ExTET in this specification. (Exciplex-Triplet Energy Transfer) There is a match.

[0167] In addition, one of the organic compounds 431 and 432 receives holes and the other receives electrons. When they approach each other, they quickly form an exciplex. Then, it quickly interacts with the other substance to form an exciplex. Most of the excitons in the light-emitting layer 444 exist as exciplexes. The band gap is smaller than that of both the organic compound 431 and the organic compound 432. The formation of the complex allows the driving voltage of the light-emitting element to be reduced.

[0168] By configuring the light-emitting layer 444 as described above, the guest material 433 (phosphorescent material ) can be efficiently obtained.

[0169] The light emitted from the light-emitting layer 443 has a peak at a shorter wavelength side than the light emitted from the light-emitting layer 444. It is preferable that the light-emitting element has a structure including a phosphorescent material that emits light of a short wavelength. Therefore, by using fluorescent light for short wavelengths, A light-emitting element with little deterioration in luminance can be provided.

[0170] In addition, the light-emitting layer 443 and the light-emitting layer 444 emit light of different wavelengths. Therefore, a light-emitting element that emits multicolor light can be manufactured. The spectrum is composed of light with different emission peaks, so there are at least two The emission spectrum has a maximum value of

[0171] The above structure is also suitable for obtaining white light emission. By making the light from the two fluorescent materials complementary to each other, white light can be emitted.

[0172] In addition, one or both of the light-emitting layers 443 and 444 may have multiple layers with different emission wavelengths. By using multiple luminescent materials, it is possible to produce high color rendering of three primary colors or four or more luminescent colors. White light can also be obtained. In this case, either one of the light-emitting layer 443 and the light-emitting layer 444 Alternatively, both may be further divided into layers, and each divided layer may contain a different light-emitting material. You can do that too.

[0173] Next, materials that can be used for the light-emitting layer 443 and the light-emitting layer 444 will be described below. do.

[0174] <Materials that can be used for the light-emitting layer 443> The light-emitting layer 443 can be formed from a material similar to that of the light-emitting layer 12 shown in Embodiment 1. Materials that can be used in 0 can be used.

[0175] <Materials that can be used for the light-emitting layer 444> In the light-emitting layer 444, the organic compound 431 (host material) is present in the largest amount by weight, and the The phosphorescent material 433 is dispersed in the organic compound 431 (host material).

[0176] Organic compounds 431 (host materials) include zinc and aluminum metal complexes, as well as oxalates. sadiazole derivatives, triazole derivatives, benzimidazole derivatives, quinoxaline derivatives Conductors, dibenzoquinoxaline derivatives, dibenzothiophene derivatives, dibenzofuran derivatives , pyrimidine derivatives, triazine derivatives, pyridine derivatives, bipyridine derivatives, phenane Other examples include aromatic amines and carbazole derivatives. In addition, the compounds having a skeleton that easily accepts electrons, as shown in the first embodiment, A compound having a skeleton that readily accepts holes or a compound having a skeleton that readily accepts holes can be used.

[0177] Guest material 433 (phosphorescent material) is iridium, rhodium, or platinum-based organic Metal complexes, or metal complexes, among which organic iridium complexes, e.g., iridium The orthometalated complex is preferably a 4H-triazole. Ligand, 1H-triazole ligand, imidazole ligand, pyridine ligand, pyrimidine The metal complexes include a pyrazine ligand, an isoquinoline ligand, and the like. Examples include platinum complexes having porphyrin ligands.

[0178] The organic compound 432 (assist material) can form an exciplex with the organic compound 431. In this case, the emission peak of the exciplex is the triplet MLCT (M absorption band of the (Etal to Ligand Charge Transfer) transition, Specifically, organic compounds 431 and 432 were selected so that they overlap with the absorption band on the longest wavelength side. 2 and the guest material 433 (phosphorescent material). However, if a thermally activated material is used instead of a phosphorescent material, the efficiency of the light-emitting element can be dramatically improved. When a delayed fluorescent material is used, the absorption band on the longest wavelength side is the singlet absorption band. Specifically, the organic compound 432 is preferably an electron-accepting compound shown in Embodiment 1. A compound having a skeleton that easily accepts holes or a compound having a skeleton that easily accepts holes is used. It is possible.

[0179] The light-emitting material contained in the light-emitting layer 444 is a material capable of converting triplet excitation energy into light. The material capable of converting triplet excitation energy into luminescence is a phosphorescent material. In addition to the above, thermally activated delayed fluorescent materials are also included. In this case, the term "thermally activated delayed fluorescent material" may be used interchangeably with "thermally activated delayed fluorescent material." The triplet excited state is upconverted to the singlet excited state by a small amount of thermal energy. A material capable of reverse intersystem crossing (reverse intersystem crossing) and efficiently emitting light (fluorescence) from the singlet excited state. In addition, the condition for efficiently obtaining thermally activated delayed fluorescence is that the triplet excitation energy The energy difference between the singlet excited energy level and the singlet excited energy level is preferably greater than 0 eV and less than 0. It is preferably 2 eV or less, and more preferably more than 0 eV and 0.1 eV or less.

[0180] In addition, the light-emitting color of the light-emitting material contained in the light-emitting layer 443 and the light-emitting material contained in the light-emitting layer 444 differs. There is no limitation, and they may be the same or different. The light emitted from each is mixed and emitted outside the device. For example, if the colors of the light emitted by both are complementary to each other, the light-emitting element will emit white light. In consideration of the reliability of the light-emitting element, the light-emitting layer 443 can emit light. The emission peak wavelength of the light-emitting material is preferably shorter than that of the light-emitting material contained in the light-emitting layer 444. It's nice.

[0181] The light-emitting layers 443 and 444 can be formed by evaporation (including vacuum evaporation), ink-jet deposition, or the like. The layer can be formed by a printing method, a coating method, a gravure printing method, or the like.

[0182] Note that the structure described in this embodiment mode may be used in appropriate combination with structures described in other embodiments. You can be there.

[0183] (Embodiment 3) This embodiment has a configuration different from that shown in the first and second embodiments. The light emitting element will be described below with reference to FIGS.

[0184] <Configuration example of light-emitting element> FIG. 4A is a schematic cross-sectional view illustrating a light-emitting element 452 of one embodiment of the present invention.

[0185] The light emitting element 452 has a plurality of light emitting units (FIG. 4( In A), there are light-emitting units 446 and 447. The unit has a similar structure to the EL layer 100 shown in FIG. The light emitting element 150 has one light emitting unit, and the light emitting element 452 has multiple light emitting units. In the present embodiment, the electrode 401 is an anode and the electrode 402 is a cathode, and the following description will be given accordingly. However, the configuration of the light emitting element 452 may be reversed.

[0186] In addition, in the light-emitting element 452 shown in FIG. 4A, the light-emitting unit 446 and the light-emitting unit The light-emitting units 446 and 447 are stacked, and a charge generating element is formed between the light-emitting units 446 and 447. The light emitting unit 446 and the light emitting unit 447 have the same configuration. For example, the light-emitting unit 446 may have a fluorescent material as a light-emitting material. It is preferable to use the EL layer 100 shown in FIG. 1 for the light-emitting unit 447.

[0187] That is, the light-emitting element 452 includes a light-emitting layer 448 and a light-emitting layer 449. The optical unit 446 includes a light-emitting layer 448, a hole injection layer 411, a hole transport layer 412, an electron The light-emitting unit 447 includes an electron-transporting layer 413 and an electron-injecting layer 414. In addition to 49, a hole injection layer 415, a hole transport layer 416, an electron transport layer 417, and an electron injection layer It has 418.

[0188] In addition, in FIG. 4A, a light emitting element having two light emitting units has been described. However, the same configuration can be applied to a light emitting element in which three or more light emitting units are stacked. As shown in the light-emitting element 452, a plurality of light-emitting units are electrically connected between a pair of electrodes. By separating the layers, high brightness light emission is possible while keeping the current density low. Furthermore, it is possible to realize a device with a longer life and a display device with lower power consumption. do.

[0189] At least one of the multiple units has the EL layer 100 shown in FIG. By applying the above structure, a light-emitting element with high luminous efficiency can be provided.

[0190] The light-emitting layer 448 includes a host material 461 and a guest material 462. The optical layer 449 includes an organic compound 471, an organic compound 472, and a guest material 473. .

[0191] In this embodiment, the light-emitting layer 449 has the same structure as the light-emitting layer 120 shown in FIG. That is, the organic compound 471, the organic compound 472, and the gate electrode 473 contained in the light-emitting layer 449 are The resist material 473 is a mixture of the organic compound 131, the organic compound 132, and the gate electrode contained in the light-emitting layer 120. The guest material 462 in the light-emitting layer 448 corresponds to the guest material 133. The fluorescent material will be explained below.

[0192] <Light Emitting Mechanism of the Light Emitting Layer 448> First, the light emitting mechanism of the light emitting layer 448 will be explained below.

[0193] In the light-emitting layer 448, carrier recombination creates an excited state. Since the host material 461 is present in a large amount compared to 2, the excited state is almost entirely in the host material 46 The electrons exist as excited states of 1. The electrons are the singlet excited state and the triplet excited state, which arise from carrier recombination. The ratio of excited states (hereafter referred to as exciton generation probability) is approximately 1:3.

[0194] First, the triplet excited energy level of the host material 461 is compared with the triplet excited energy level of the guest material 462. The case where the energy level is higher than the excited energy level will be explained below.

[0195] The triplet excited energy level of the host material 461 is converted to the triplet excited energy level of the guest material 462. However, energy transfer occurs between the guest and the non-guest energy levels. Since the material 462 is a fluorescent material, when the guest material 462 is in a triplet excited state, visible light is emitted. Therefore, the triplet excited state energy of the host material 461 is Therefore, the triplet excitation energy level of the host material 461 is difficult to utilize as light emission. When the energy level is higher than the triplet excited energy level of the guest material 462, the injected It is difficult to utilize more than about 25% of the carriers for light emission.

[0196] Next, the energy levels of the host material 461 and the guest material 462 in the light-emitting layer 448 are The correlation between the positions is shown in Figure 4(B). The notations and symbols in Figure 4(B) are as follows: be. Host (461): Host material 461 Guest (462): Guest material 462 (fluorescent material) ·S FH : The lowest singlet excited state of the host material 461 T FH : The lowest triplet excited state of the host material 461 ·S FG : The lowest level of the singlet excited state of guest material 462 (fluorescent material) T FG : The lowest level of the triplet excited state of guest material 462 (fluorescent material)

[0197] As shown in FIG. 4(B), the triplet excited energy level of the guest material 462 (FIG. 4(B) In T FG ) is the triplet excited energy level of the host material 461 (see FIG. 4(B)). T FH ) is a higher configuration.

[0198] As shown in Figure 4(B), triplet-triplet annihilation (TTA) By using the (Implet Annihilation) (see Route E9 in Figure 4(B)), When doublet excitons collide with each other, part of their excitation energy is transferred to the host material. The lowest level of the singlet excited state of 1 (S FH ) is converted to the singlet state of the host material 461. The lowest excited state (S FH ) from the lower level guest material 462 (fluorescent The lowest singlet excited state (S FG ) energy transfer occurs (Figure 4( B) Route E 10 , the guest material 462 (fluorescent material) emits light.

[0199] The triplet excitation energy level of the host material 461 is the triplet excitation energy level of the guest material 462. energy level, so T FG The energy of T FH Nienel Gee movement (Route E in Figure 4(B) 11 (see reference) and is used for TTA.

[0200] By configuring the light-emitting layer 448 as described above, light emission from the guest material 462 of the light-emitting layer 448 can be obtained efficiently.

[0201] The light-emitting layer 448 and the light-emitting layer 449 are configured to emit light of different wavelengths. Therefore, a light-emitting element that emits multicolor light can be manufactured. The spectrum is composed of light with different emission peaks, so there are at least two The emission spectrum has a maximum value of

[0202] The above structure is also suitable for obtaining white light emission. By making the light from the two fluorescent materials complementary to each other, white light can be emitted.

[0203] In addition, one or both of the light-emitting layer 448 and the light-emitting layer 449 may have a plurality of layers each having different emission wavelengths. By using multiple luminescent materials, it is possible to produce high color rendering of three primary colors or four or more luminescent colors. White light can also be obtained. In this case, either one of the light-emitting layer 448 and the light-emitting layer 449 Alternatively, both may be further divided into layers, and each divided layer may contain a different light-emitting material. You can do that too.

[0204] <Light Emission Mechanism of the Light Emitting Layer 449> The light emitting mechanism of the light emitting layer 449 is the same as the light emitting mechanism of the light emitting layer 120 shown in FIG.

[0205] Next, materials that can be used for the light-emitting layer 448 and the light-emitting layer 449 will be described below. do.

[0206] <Materials that can be used for the light-emitting layer 448> In the light-emitting layer 448, the host material 461 is present in the largest amount by weight, and the guest material 462 The fluorescent material is dispersed in the host material 461. The energy level is higher than the singlet excited energy level of the guest material 462 (fluorescent material). The triplet excited energy level of the host material 461 is the triplet excited energy level of the guest material 462 (fluorescent material). It is preferable that the energy level is lower than the first excited energy level.

[0207] The host material 461 is preferably an anthracene derivative or a tetracene derivative. These derivatives have high singlet excitation energy levels and low triplet excitation energy levels. Specifically, 9-phenyl-3-[4-(10-phenyl-9-anthryl )phenyl]-9H-carbazole (abbreviation: PCzPA), 3-[4-(1-naphthyl) -phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 9-[4-(1 0-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: CzPA ), 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c, g]carbazole (abbreviation: cgDBCzPA), 6-[3-(9,10-diphenyl-2 -anthryl)phenyl]-benzo[b]naphtho[1,2-d]furan (abbreviation: 2mBn fPPA), 9-phenyl-10-{4-(9-phenyl-9H-fluoren-9-yl )-biphenyl-4'-yl}-anthracene (abbreviation: FLPPA), etc. Alternatively, 5,12-diphenyltetracene, 5,12-bis(biphenyl-2-yl) Examples include tetracene.

[0208] Guest materials 462 (fluorescent materials) include pyrene derivatives, anthracene derivatives, trifluoromethane derivatives, and fluoromethane derivatives. phenylene derivatives, fluorene derivatives, carbazole derivatives, dibenzothiophene derivatives, Dibenzofuran derivatives, dibenzoquinoxaline derivatives, quinoxaline derivatives, pyridine derivatives Examples of suitable conductors include conductors, pyrimidine derivatives, phenanthrene derivatives, and naphthalene derivatives. In particular, pyrene derivatives are preferred because they have a high luminescence quantum yield. Specific examples of pyrene derivatives include: N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H- Fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemF LPAPrn), N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl) Phenyl]-N,N'-diphenylpyrene-1,6-diamine (abbreviation: 1,6FLPAP rn), N,N'-bis(dibenzofuran-2-yl)-N,N'-diphenylpyrene- 1,6-diamine (abbreviation: 1,6FrAPrn), N,N'-bis(dibenzothiophene) -2-yl)-N,N'-diphenylpyrene-1,6-diamine (abbreviation: 1,6ThAP rn) and the like. In addition, the fluorescent materials exemplified in the first embodiment can be used. .

[0209] <Materials that can be used for the light-emitting layer 449> The light-emitting layer 449 can be formed from a material similar to that of the light-emitting layer 12 shown in Embodiment 1. Materials that can be used in 0 can be used.

[0210] In addition, the light emitting color of the light emitting material contained in the light emitting layer 448 and the light emitting material contained in the light emitting layer 449 differs. There is no limitation, and they may be the same or different. The light emitted from each is mixed and emitted outside the device. For example, if the colors of the two lights are complementary to each other, the light-emitting element will emit white light. In consideration of the reliability of the light-emitting element, the light-emitting layer 448 can emit light of a wavelength of 1000 nm. The emission peak wavelength of the light-emitting material is preferably shorter than that of the light-emitting material contained in the light-emitting layer 449. It's nice.

[0211] The light-emitting layer 448 and the light-emitting layer 449 can be formed by a deposition method (including a vacuum deposition method), an ink-jet method, or the like. The layer can be formed by a printing method, a coating method, a gravure printing method, or the like.

[0212] The above configuration may be appropriately combined with other embodiments or other configurations in this embodiment. It is possible to do this.

[0213] (Fourth embodiment) In this embodiment, a display device including a light-emitting element according to one embodiment of the present invention will be described with reference to FIG. (B) will be used for explanation.

[0214] Note that FIG. 5(A) is a block diagram illustrating a display device of one embodiment of the present invention, and FIG. 1B is a circuit diagram illustrating a pixel circuit included in a display device of one embodiment of the present invention.

[0215] <Explanation about the display device> The display device shown in FIG. 5A includes 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 circuit section) that is disposed outside the pixel section 802 and has a circuit for driving the pixel. (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 806) ) and a terminal portion 807. Note that the protection circuit 806 may not be provided. Good too.

[0216] 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 all of the driving circuit is not formed on the same substrate as the pixel portion 802, A part or the whole of the path portion 804 is made of COG (Chip On Glass) or TAB (Tip On Glass). This can be implemented using the APEX Automated Bonding.

[0217] 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). The display device has a circuit for driving a plurality of display elements (hereinafter referred to as pixel circuit 801), The path portion 804 is a circuit for outputting a signal (scanning signal) for selecting a pixel (hereinafter referred to as a scanning line driving circuit 804a), for supplying signals (data signals) for driving the display elements of the pixels. The signal line driver circuit 804b includes a driver circuit such as the circuit (hereinafter referred to as a signal line driver circuit 804b).

[0218] The scanning line driver circuit 804a includes a shift register and the like. A signal for driving the shift register is inputted through the terminal portion 807, and a signal is outputted. For example, a start pulse signal, a clock signal, etc. are input to the scanning line driver circuit 804a. The scanning line driving circuit 804a is connected to the wiring to which the scanning signal is applied (hereinafter referred to as the wiring). The scanning lines GL_1 to GL_X are connected to the gate electrode GL_1. A plurality of driving circuits 804a are provided, and the scanning lines GL_1 to GL_3 are driven by the plurality of scanning line driving circuits 804a. 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 other signals.

[0219] The signal line driver circuit 804b includes a shift register and the like. Through the terminal portion 807, signals for driving the shift register as well as the source of the data signal are transmitted. The signal line driver circuit 804b receives the image signal and drives the pixel circuit The signal line driver circuit 804b has a function of generating a data signal to be written to the signal line driver circuit 804b. A data signal is generated in accordance with 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 signal. The data lines DL_1 to DL_Y are connected to the data lines DL_2 through DL_Y. 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.

[0220] 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-divided and output as a data signal. The signal line driver circuit 804b may be configured using the same.

[0221] 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 input via the data line DL, and a data signal is given via one of the data lines DL. Each of the pixel circuits 801 receives a data signal via a scanning line driving circuit. 804a controls the writing and holding of data of the data signal. The second pixel circuit 801 is connected to the scanning line driving circuit GL_m (m is a natural number equal to or less than X) via the scanning line GL_m. 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 the signal line driver circuit 804b (n is a natural number equal to or less than Y).

[0222] The protection circuit 806 shown in FIG. 5A is, for example, a protection circuit including a scanning line driver circuit 804a and a pixel circuit 80 1. Alternatively, the protection circuit 806 is connected to the signal line driving circuit The protection circuit 804b is connected to the data line DL, which is the wiring between the protection circuit 804b and the pixel circuit 801. The 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 formed on the wiring between the signal line driver circuit 804b and the terminal portion 807. The terminal portion 807 can be connected to the display device via a power supply and a control circuit. This refers to the part where terminals for inputting control signals and image signals are provided.

[0223] When a potential outside a certain range is applied to the wiring to which the protection circuit 806 is connected, the protection circuit 806 This is a circuit that brings one wire into electrical continuity with another wire.

[0224] As shown in FIG. 5A, a pixel portion 802 and a driver circuit portion 804 are provided with a protection circuit 806. By providing a This can improve the resistance of the display device to overcurrents caused by electrical discharges, etc. However, the configuration of the protection circuit 806 is not limited to this. For example, the protection circuit 806 may be provided in the scanning line driving circuit 804a. A configuration in which a protection circuit 806 is connected, or a configuration in which 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. You can also do this.

[0225] In FIG. 5A, the scanning line driver circuit 804a and the signal line driver circuit 804b However, the present invention is not limited to this configuration. For example, only the scanning line driver circuit 804a is formed, and a separately prepared signal line driver circuit is formed. Mounting a substrate (for example, a drive circuit substrate formed of a single crystal semiconductor film or a polycrystalline semiconductor film) It may also be configured as

[0226] <Pixel circuit configuration example> The plurality of pixel circuits 801 shown in FIG. 5A may have the configuration shown in FIG. 5B, for example. can be done.

[0227] The pixel circuit 801 shown in FIG. 5B includes transistors 852 and 854 and a capacitor 862. and a light-emitting element 872.

[0228] One of the source electrode and the drain electrode of the transistor 852 is supplied with a data signal. The transistor 8 is electrically connected to a wiring (hereinafter referred to as a data line DL_n). The gate electrode 52 is connected to a wiring (hereinafter referred to as a scanning line GL_m) to which a gate signal is applied. electrically connected.

[0229] The transistor 852 has a function of controlling writing of data signals.

[0230] One of the 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 transistor 852. The second electrode is electrically connected to the other of the first and second electrodes.

[0231] The capacitor 862 functions as a storage capacitor for holding written data.

[0232] One of the source electrode and the drain electrode of the transistor 854 is connected to the potential supply line VL_a. Furthermore, the gate electrode of transistor 854 is electrically connected to the It is electrically connected to the other of the source electrode and the drain electrode.

[0233] One of the anode and cathode of the light emitting element 872 is electrically connected to the potential supply line VL_b. The other is electrically connected to the other of the source electrode and drain electrode of the transistor 854. will be done.

[0234] The light-emitting element 872 may be any of the light-emitting elements described in any of Embodiments 1 to 3. can be done.

[0235] 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.

[0236] In a display device having the pixel circuit 801 of FIG. 5B, for example, the scanning line The pixel circuits 801 in each row are selected in sequence by the driving circuit 804a, and the transistors 852 are turned on. The data signal is written in this state.

[0237] The pixel circuit 801 in which data has been written is turned off by turning off the transistor 852. Furthermore, the potential of the transistor 854 changes depending on 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 at a brightness that corresponds to the flow rate. By repeating this process row by row, an image can be displayed.

[0238] Furthermore, the light-emitting element of one embodiment of the present invention may be an active matrix light-emitting element having an active element in a pixel of a display device. The display device is a passive matrix type that does not have active elements in the pixels. It can be applied to each method.

[0239] In the active matrix system, the active element (active element, nonlinear element) is a transistor. 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.

[0240] Other than the 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 (active elements). Since it does not use any nonlinear elements, there are fewer manufacturing steps, which reduces manufacturing costs and improves yield. Alternatively, active elements (active elements, non-linear elements) can be used. Since the aperture ratio is not increased, it is possible to achieve low power consumption or high brightness. This can be done.

[0241] The structure shown in this embodiment mode may be appropriately combined with structures shown in other embodiment modes or examples. It can be used in combination.

[0242] (Embodiment 5) In this embodiment, a display device including a light-emitting element of one embodiment of the present invention and a display device including the light-emitting element An electronic device having an input device attached thereto will be described with reference to FIGS. 6 to 10. FIG.

[0243] <Touch panel explanation 1> In the present embodiment, an example of an electronic device is a device that combines a display device and an input device. The touch panel 2000 will be described. The case where the .

[0244] 6(A) and (B) are perspective views of the touch panel 2000. 2, for clarity, only representative components of touch panel 2000 are shown.

[0245] The touch panel 2000 includes a display device 2501 and a touch sensor 2595 (see FIG. 6 (B)). The touch panel 2000 also includes a substrate 2510, a substrate 2570, and a substrate 2590. Note that the substrate 2510, the substrate 2570, and the substrate 2590 may all be However, any one of the substrates 2510, 2570, and 2590 has flexibility. Alternatively, the entire structure may not be flexible.

[0246] The display device 2501 has 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 cable, part of which forms the terminal 2519. The terminal 2519 is an FPC2509 (1) and electrically connect.

[0247] 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. The terminal is electrically connected to the FPC2509(2). In FIG. 6(B), for clarity, the back side of the substrate 2590 (the substrate 2510) is shown. Electrodes and wiring of the touch sensor 2595 provided on the opposite surface are shown by solid lines.

[0248] As the touch sensor 2595, for example, a capacitance type touch sensor can be applied. The capacitive type includes a surface type electrostatic capacitance type and a projected type electrostatic capacitance type.

[0249] The projected capacitive type is mainly divided into self-capacitance type and mutual capacitance type, which differ mainly in the driving method. The mutual capacitance method is preferable because it allows simultaneous multi-point detection.

[0250] The touch sensor 2595 shown in FIG. 6B is a projected capacitive touch sensor. This is a configuration in which the above is applied.

[0251] The touch sensor 2595 can detect the proximity or contact of a detection object such as a finger. Various sensors can be applied.

[0252] The projected capacitive touch sensor 2595 has an electrode 2591 and an electrode 2592. The electrode 2591 is electrically connected to one of the plurality of wirings 2598, and the electrode 2592 is It is electrically connected to any other of the plurality of wirings 2598.

[0253] As shown in FIGS. 6(A) and 6(B), the electrodes 2592 are made of a plurality of electrodes repeatedly arranged in one direction. It has a shape in which quadrilaterals are connected at their corners.

[0254] The electrode 2591 is quadrilateral and is repeated in a direction intersecting the direction in which the electrode 2592 extends. are placed.

[0255] 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 where no electrodes are provided, reducing variations in transmittance. As a result, the variation in brightness of light passing through the touch sensor 2595 can be reduced. can be done.

[0256] 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 A plurality of electrodes 2592 are provided at intervals so that there is an area where they do not overlap with the electrodes 2591. In this case, a contact between two adjacent electrodes 2592 may be provided. Providing an insulated dummy electrode is preferable because it can reduce the area of the region with different transmittance. .

[0257] <Explanation about the display device> Next, the display device 2501 will be described in detail with reference to FIG. , which corresponds to a cross-sectional view taken along the dashed dotted line X1-X2 shown in FIG. 6(B).

[0258] The display device 2501 has a plurality of pixels arranged in a matrix. and a pixel circuit for driving the display element.

[0259] In the following description, a light emitting element that emits white light is applied to a display element. However, the display element is not limited to this. For example, To achieve different colors, light emitting elements with different luminescent colors may be applied.

[0260] 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 1 × 10 -6 g·m -2 ·day -1 It is possible that A flexible material can be preferably used. Alternatively, the thermal expansion coefficient of the substrate 2510 and the It is preferable to use a material whose coefficient of thermal expansion is approximately equal to that of the plate 2570. For example, is 1×10 -3 / K or less, preferably 5×10 -5 / K or less, more preferably 1×10 - 5 A material having a solubility of 0.1 kJ / K or less can be suitably used.

[0261] The substrate 2510 has an insulating layer 2510a that prevents 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. The substrate 2570 is a laminate having a layer 510c and a layer 510d. and a flexible substrate 2570b. 2570b and an adhesive layer 2570c that bonds them together.

[0262] The adhesive layer 2510c and the adhesive layer 2570c may be made of, for example, polyester or polyolefin. Polyimide, polycarbonate or acrylic Polyurethane resin, epoxy resin, or silicone resin can be used. Any material containing a resin having a siloxane bond can be used.

[0263] 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 layer is larger than that of air. When light is extracted from the 2560 side, the sealing layer 2560 can also serve as an optical bonding layer. do.

[0264] 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 have a light emitting element 2550R. An inert gas (nitrogen, argon, etc.) may be filled. In addition, a desiccant may be added to the inert gas. It is also possible to provide a structure in which moisture and the like are absorbed by the resin. It may be filled with a resin, such as PVC (polyvinyl chloride) resin or acrylic resin. , polyimide resin, epoxy resin, silicone resin, PVB (polyvinyl butyral )-based resin or EVA (ethylene vinyl acetate)-based resin can be used. As the sealing material, it is preferable to use, for example, an epoxy resin or glass frit. It is also preferable to use a material that is impermeable to moisture and oxygen as the sealing material. It is suitable.

[0265] The display device 2501 also has a pixel 2502R. The pixel 2502R is a light-emitting model. It has a Joule 2580R.

[0266] The pixel 2502R includes a light emitting element 2550R and a power supply for 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 It has a colored layer 2567R.

[0267] The light emitting element 2550R includes a lower electrode, an upper electrode, and an EL layer between the lower electrode and the upper electrode. The light-emitting element 2550R may be, for example, any of the light-emitting elements described in Embodiments 1 to 3. Optical elements can be applied.

[0268] 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.

[0269] Furthermore, when the sealing layer 2560 is provided on the side from which light is extracted, the sealing layer 2560 It contacts the optical element 2550R and the colored layer 2567R.

[0270] 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.

[0271] Furthermore, the display device 2501 is provided with a light-shielding layer 2567BM in the light-emitting direction. The light-shielding layer 2567BM is provided so as to surround the colored layer 2567R.

[0272] The colored layer 2567R only needs to have a function of transmitting light in a specific wavelength band. For example, a color filter that transmits light in the red wavelength band, a color filter that transmits light in the green wavelength band, A color filter that transmits light in the blue wavelength band, and a color filter that transmits light in the yellow wavelength band. A transparent color filter can be used. Each color filter is made of various materials. The method includes printing, inkjet printing, and etching using photolithography technology. It can be formed by.

[0273] The display device 2501 is also provided with an insulating layer 2521. The insulating layer 2521 is formed 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 transistor 2502t and the like from being reduced due to the diffusion of impurities. It can be suppressed.

[0274] 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 the 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.

[0275] The scanning line driver circuit 2503g(1) includes a transistor 2503t and a capacitor 2503c. The driver circuit and the pixel circuit can be formed on the same substrate in the same process. do.

[0276] Moreover, wiring 2511 capable of supplying signals is provided on the substrate 2510 . A terminal 2519 is provided on the wiring 2511. The terminal 2519 is also provided with an FP C2509(1) is electrically connected. FPC2509(1) also transmits video signals, It has the function of supplying clock signals, start signals, reset signals, etc. 509(1) includes a printed wiring board (PWB) d) may be attached.

[0277] In addition, transistors with various structures can be applied to the display device 2501. In 7(A), a case where a bottom gate type transistor is applied is illustrated. However, the present invention is not limited to this. For example, a top-gate transistor shown in FIG. 7B may be used. may be applied to the display device 2501.

[0278] In addition, there is no particular limitation on the polarity of the transistor 2502t and the transistor 2503t. There is no restriction on the type of transistor, and it can be a structure with N-type and P-type transistors, or a structure with N-type transistors or P-type transistors. Alternatively, a structure consisting of only one of the transistors may be used. There is no particular limitation on the crystallinity of the semiconductor film used in 502t and 2503t. For example, an amorphous semiconductor film or a crystalline semiconductor film can be used. , Group 13 semiconductors (e.g., semiconductors containing gallium), Group 14 semiconductors (e.g., silicon semiconductors having elements), compound semiconductors (including oxide semiconductors), organic semiconductors, etc. Either one or both of the transistors 2502t and 2503t can be connected. On the other hand, the energy gap is 2 eV or more, preferably 2.5 eV or more, and more preferably By using an oxide semiconductor with a conductivity of 3 eV or more, the off-state current of a transistor can be reduced. The oxide semiconductor is preferably an In-Ga oxide or an In-M-Zn oxide. (M is aluminum (Al), gallium (Ga), yttrium (Y), zirconium Zirconium (Zr), Lanthanum (La), Cerium (Ce), Tin (Sn), Hafnium (Hf) , or neodymium (Nd).

[0279] <Explanation about touch sensors> Next, the touch sensor 2595 will be described in detail with reference to FIG. 7(C). ) corresponds to a cross-sectional view taken along the dashed dotted line X3-X4 shown in FIG. 6(B).

[0280] The touch sensor 2595 is made up of 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 the adjacent electrodes 25 91 and a wiring 2594 that electrically connects them.

[0281] The electrode 2591 and the electrode 2592 are formed using a light-transmitting conductive material. Examples of conductive materials having the formula include indium oxide, indium tin oxide, and indium zinc oxide. Conductive oxides such as zinc oxide, zinc oxide, and 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 film can be formed by reducing the graphene oxide film formed on the substrate. For example, a method of applying heat can be mentioned.

[0282] For example, a film of a light-transmitting conductive material is formed on the substrate 2590 by sputtering. After that, various patterning techniques such as photolithography are used to remove unnecessary parts. , an electrode 2591 and an electrode 2592 can be formed.

[0283] The insulating layer 2593 may be made of a resin such as acrylic or epoxy. In addition to resins with siloxane bonds, silicon oxide, silicon oxynitride, aluminum oxide, Inorganic insulating materials such as rubber can also be used.

[0284] An opening reaching the electrode 2591 is provided in the insulating layer 2593, and a wiring 2594 is adjacent to the opening. The transparent conductive material is used to increase the aperture ratio of the touch panel. Therefore, it can be suitably used for the wiring 2594. A material having higher conductivity than the electrode 2592 is preferable for the wiring 2594 because it can reduce electrical resistance. It can be used appropriately.

[0285] The electrodes 2592 extend in one direction, and a plurality of electrodes 2592 are provided in a stripe pattern. Moreover, the wiring 2594 is provided so as to intersect with the electrode 2592.

[0286] A pair of electrodes 2591 is provided with one electrode 2592 sandwiched therebetween. A pair of electrodes 2591 are electrically connected.

[0287] The plurality of electrodes 2591 are arranged in a direction that is not necessarily perpendicular to one electrode 2592. The angle does not have to be 0 degrees, and may be greater than 0 degrees but less than 90 degrees.

[0288] 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.

[0289] An insulating layer covering the insulating layer 2593 and the wiring 2594 is provided, and the touch sensor 2595 may be protected.

[0290] The connection layer 2599 electrically connects the wiring 2598 and the FPC 2509(2). .

[0291] The connection layer 2599 is made of an anisotropic conductive film (ACF). conductive film) and anisotropic conductive paste (ACP) Conductive Paste) can be used.

[0292] <Touch panel explanation 2> Next, the touch panel 2000 will be described in detail with reference to FIG. ) corresponds to a cross-sectional view taken along the dashed dotted line X5-X6 shown in FIG. 6(A).

[0293] The touch panel 2000 shown in FIG. 8A is the same as the display device 2501 described in FIG. 7A. , and the touch sensor 2595 explained in FIG. 7(C) are bonded together.

[0294] The touch panel 2000 shown in FIG. 8(A) is similar to the touch panel 2000 described in FIGS. 7(A) and 7(C). In addition to this configuration, it has an adhesive layer 2597 and an anti-reflection layer 2567p.

[0295] 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. The adhesive layer 2597 is preferably transparent. The material 597 can be a thermosetting resin or an ultraviolet curing resin. For example, Acrylic resin, urethane resin, epoxy resin, or siloxane resin may be used. This can be done.

[0296] The anti-reflection layer 2567p is provided at a position overlapping the pixel. For example, a circular polarizing plate can be used.

[0297] Next, for a touch panel having a different configuration from that shown in FIG. 8(A), we will use FIG. 8(B) to I will explain.

[0298] 8(B) is a cross-sectional view of the touch panel 2001. The touch panel shown in FIG. 2001 is a touch panel 2000 shown in FIG. 8(A) and a display device 2501. The position of the sensor 2595 is different. Here, we will explain the different configuration in detail and compare it with the similar configuration. The description of the touch panel 2000 is cited for the parts where the configuration can be used.

[0299] The colored layer 2567R is located so as to overlap the light emitting element 2550R. The light emitting element 2550R 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 is transmitted through the colored layer 2567R, The light is emitted to the outside of light emitting module 2580R in the direction of the arrow shown inside.

[0300] The touch sensor 2595 is provided on the substrate 2510 side of the display device 2501. .

[0301] 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.

[0302] As shown in FIGS. 8(A) and 8(B), the light emitted from the light emitting element is incident on the upper and lower surfaces of the substrate. It may be injected in either one or both directions.

[0303] <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 FIG.

[0304] FIG. 9(A) is a block diagram showing the configuration of a mutual capacitance type touch sensor. ) shows a pulse voltage output circuit 2601 and a current detection circuit 2602. In (A), the electrodes 2621 to which the pulse voltage is applied are designated as X1-X6, and the change in current is detected. The electrodes 2622 to be detected are shown as Y1-Y6, each having six wires. 9(A) shows a capacitance 2603 formed by overlapping an electrode 2621 and an electrode 2622. The functions of the electrode 2621 and the electrode 2622 may be interchangeable. stomach.

[0305] The pulse voltage output circuit 2601 is a circuit for applying pulses to the X1-X6 wirings 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 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.

[0306] The current detection circuit 2602 detects the change in the mutual capacitance of the capacitor 2603 between the wires Y1 and Y6. This is a circuit for detecting changes in current. 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 decrease in the current value is detected. The detection may be performed using an integrating circuit or the like.

[0307] Next, FIG. 9B shows the input / output of the mutual capacitance type touch sensor shown in FIG. 9A. The timing chart of the waveform is shown in Fig. 9(B). In addition, in Figure 9(B), when no object is detected (non-touch ) and when detecting an object to be detected (touch). For the wire Y6, a waveform is shown in which the voltage value corresponds to the detected current value.

[0308] A pulse voltage is applied to the wires X1-X6 in order, 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 contact point, the current value decreases, and the corresponding voltage waveform also changes. do.

[0309] 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.

[0310] <Sensor circuit explanation> In addition, in FIG. 9(A), a panel in which only a capacitor 2603 is provided at the intersection of the wiring as a touch sensor is used. The configuration of a passive matrix touch sensor has been shown, but an active matrix type touch sensor having a transistor and a capacitor has also been shown. An active matrix touch sensor may be used. An example of the sensor circuit included in the sensor is shown in Figure 10.

[0311] The sensor circuit shown in FIG. 10 includes a capacitor 2603, a transistor 2611, and a transistor 2612 and a transistor 2613.

[0312] A signal G2 is applied to the gate of the transistor 2613, and a signal G3 is applied to either the source or the drain of the transistor 2613. A voltage VRES is applied, and the other is connected to one electrode of the capacitor 2603 and the transistor 2611 The transistor 2611 has a source and a drain electrically connected to the gate of the transistor 2611. The source or drain of the transistor 2612 is electrically connected to the voltage VS The transistor 2612 receives a signal G1 at its gate and a signal S at its 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.

[0313] Next, the operation of the sensor circuit shown in Fig. 10 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 signal G2 is connected. When a potential that turns off the transistor 2613 is applied, the potential of the node n Retained.

[0314] Next, the mutual capacitance of the capacitor 2603 changes when a detection object such as a finger approaches or touches the sensor. As a result, the potential of the node n changes from VRES.

[0315] The read operation applies a potential to the signal G1 that turns on the transistor 2612. The current flowing through the transistor 2611 in accordance with the potential of the node n, that is, the current flowing 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.

[0316] 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 This allows the voltage to be held 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.

[0317] The structure shown in this embodiment mode may be appropriately combined with structures shown in other embodiment modes or examples. It can be used in combination.

[0318] (Embodiment 6) 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 explained with reference to FIGS. 11 and 12.

[0319] <Explanation about the display module> The display module 8000 shown in FIG. 11 includes an upper cover 8001 and a lower cover 8002. Between them, the touch sensor 8004 connected to FPC8003 and the touch sensor 8005 connected to FPC8006 are A display device 8006, a frame 8009, a printed circuit board 8010, and a battery 8011 are included. do.

[0320] The light-emitting element of one embodiment of the present invention can be used for the display device 8006, for example.

[0321] The upper cover 8001 and the lower cover 8002 are connected to the touch sensor 8004 and the display device 8005. The shape and dimensions can be changed appropriately to match the size of 006.

[0322] The touch sensor 8004 is a resistive or capacitive touch sensor mounted on the display device 8 8006. In addition, the opposing substrate (sealing substrate) of the display device 8006 It is also possible to provide a touch sensor function to the display device 8006. It is also possible to provide an optical sensor in each pixel to form an optical touch sensor.

[0323] 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 frame 8009 may also function as a heat sink.

[0324] 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 if a commercial power source is used.

[0325] In addition, the display module 8000 includes components such as a polarizing plate, a retardation plate, and a prism sheet. It may also be provided in addition.

[0326] <Electronic device instructions> 12(A) to 12(G) are diagrams showing electronic devices. These electronic devices are housed in a housing. A body 9000, a display unit 9001, a speaker 9003, operation keys 9005 (power switch, 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 It may have a microphone 9008, etc.

[0327] The electronic devices shown in FIGS. 12A to 12G can have various functions. For example, functions to display various information (still images, videos, text images, etc.) on the display, Sensor function, calendar, date or time display function, various software ( It has the function of controlling processing by using 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 It should be noted that the functions shown in FIGS. 12(A) to 12(G) can be implemented. The functions that the electronic device shown in the figure can have are not limited to these, and it may have various functions. Although not shown in FIGS. 12(A) to 12(G), the electronic device may include: The electronic device may be provided with a camera or the like to take still images. The function to take pictures, take videos, and save the images to a recording medium (external or built-in to the camera) ) and a function to display the captured image on the display unit.

[0328] The electronic devices shown in FIGS. 12A to 12G will be described in detail below.

[0329] FIG. 12A is a perspective view showing a mobile information terminal 9100. The display portion 9001 is flexible. The display unit 9001 can be incorporated along the screen. It is equipped with a touch panel, 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.

[0330] 12B 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, it can be used as a smartphone. Although the speaker 9003, the connection terminal 9006, the sensor 9007, etc. are omitted in the illustration, It can be installed in the same position as the mobile information terminal 9100 shown in FIG. 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. 9051 shown in a dashed rectangle can be displayed on one side of the display unit 90. 01. An example of the information 9051 is an e-mail A display that notifies you of incoming calls, SNS (social networking services), etc. , subject of email or SNS, sender name of email or SNS, date and time, time, The remaining battery level, antenna reception strength, etc. Or, information 9051 is displayed. In place of the information 9051, an operation button 9050 or the like may be displayed.

[0331] 12C is a perspective view showing a portable information terminal 9102. The portable information terminal 9102 is , and has the function of displaying information on three or more surfaces 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 stores the portable information terminal 9102 in the breast pocket of his / her clothes. In this state, the display (information 9053 in this case) can be confirmed. The telephone number or name of the caller is displayed in a position that can be observed from above the mobile information terminal 9102. The user can view the display without taking the mobile information terminal 9102 out of his pocket. You can check the call and decide whether to accept it or not.

[0332] 12(D) is a perspective view showing a wristwatch-type portable information terminal 9200. The 9200 is suitable for mobile phone calls, e-mail, document browsing and writing, music playback, and internet communications. It is possible to run various applications such as computer games. The display surface of the display unit 9001 is curved, and the display is performed 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, handset 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. It may also be possible to supply power wirelessly without going through 6.

[0333] 12(E), (F), and (G) are perspective views showing a foldable portable information terminal 9201. 12(E) is a perspective view of the portable information terminal 9201 in an unfolded state, and FIG. (F) shows the mobile information terminal 9201 being changed from one of the unfolded state and the folded state to the other. 12(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 easily portable when 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 01 is made up of three housings 9000 connected by hinges 9055. The two housings 9000 are supported by the hinge 9055. This allows the portable information terminal 9201 to 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.

[0334] The electronic device described in this embodiment has a display unit for displaying some information. However, the light-emitting element of one embodiment of the present invention is not limited to an electronic device that does not have a display portion. In addition, the present invention can be applied to the display unit of the electronic device described in this embodiment. In the case of a display device, it is possible to provide a display that is flexible and can display information along a curved display surface, or a display device that can be folded. Although the configuration of the display unit is exemplified as being foldable, the present invention is not limited to this. The display may be displayed on the display unit.

[0335] The structure shown in this embodiment mode may be combined as appropriate with structures shown in other embodiment modes or examples. It can be used in combination.

[0336] (Embodiment 7) In this embodiment, an example of a lighting device to which a light-emitting element according to one embodiment of the present invention is applied will be described. This will be explained using FIG.

[0337] FIG. 13 shows an example in which the light-emitting element is used as an indoor lighting device 8501. Since the surface area can be increased, a large-area lighting device can be formed. By using a housing having the above structure, a lighting device 8502 having a curved light-emitting area can be formed. The light-emitting element shown in this embodiment mode has a thin film shape, and the housing can be designed with a high degree of freedom. Therefore, it is possible to create lighting devices with various elaborate designs. A large lighting device 8503 may be provided on the wall. A touch sensor may be provided in 503 to turn the power on or off.

[0338] In addition, by using light-emitting elements on the surface of the table, it has the function of a table. The lighting device 8504 can be used as a lighting device. This allows the lighting device to function as furniture.

[0339] As described above, various lighting devices using light-emitting elements can be obtained. This device is included in one aspect of the present invention.

[0340] The structure described in this embodiment mode may be used in appropriate combination with structures described in other embodiments. You can be there. [Example]

[0341] In this example, a thermally activated delayed fluorescent substance (first organic compound) and a host material (second organic compound) were used. The light-emitting element (light-emitting element 1 and An example of fabricating a light-emitting element 2) is shown in FIG. 14. A cross-sectional view of the light-emitting element fabricated in this example is shown in FIG. The details of the molecular structures are shown in Table 4. The structures and abbreviations of the compounds used are shown below. For other compounds, refer to the first embodiment.

[0342] [ka]

[0343] [Table 4]

[0344] The methods for fabricating the light-emitting elements 1 and 2 are described below.

[0345] <Fabrication of Light-Emitting Device 1> An electrode 501 made of indium tin oxide containing silicon oxide (abbreviated as ITS) was formed on a substrate 520. 0) was formed by sputtering to a thickness of 110 nm. The electrode area is 4 mm 2 (2mm x 2mm).

[0346] Next, in order to form a light emitting element on the substrate 520, the surface of the substrate is washed with water as a pretreatment. After heat treatment at 200°C for 1 hour, UV ozone treatment was performed for 370 seconds.

[0347] Next, the substrate 52 on which the electrode 501 is formed is placed so that the surface on which the electrode 501 is formed faces downward. 0 to 1 x 10 -4 The substrate holder was placed in a vacuum deposition device that was depressurized to about Pa. Then, DBT3P-II and oxidized Molybdenum (MoO3) and the weight ratio (DBT3P-II:MoO3) is 1:0.5. The co-evaporation was carried out so that the thickness of the layer was 70 nm.

[0348] Next, a hole transport layer 532 was formed on the hole injection layer 531 by depositing PhCzGI to a thickness of 20 nm. The vapor deposition was carried out as follows.

[0349] Next, a light-emitting layer 521 containing PCCzPTzn and 4,6mCz P2Pm and 1,6mMemFLPAPrn were mixed in a weight ratio of (PCCzPTzn:4,6m CzP2Pm:1,6mMemFLPAPrn) becomes 0.3:0.7:0.0025 The light-emitting layer 521 was co-deposited to a thickness of 30 nm. zPTzn is the thermally activated delayed fluorescent substance (first organic compound), and 4,6mCzP2Pm is The host material (second organic compound) is 1,6mMemFLPAPrn, and the guest material is 1,6mMemFLPAPrn. be.

[0350] Next, on the light-emitting layer 521, 4,6mCzP2P was formed as electron transport layers 533a and 533b. m and bathophenanthroline (abbreviation: Bphen), each with a thickness of 15 nm. The deposition was carried out in this order.

[0351] Next, lithium fluoride (abbreviation: Li ) was deposited on the electron transport layer 533b as the electron injection layer 534. F) was evaporated to a thickness of 1 nm.

[0352] Next, aluminum (Al) was deposited on the electron injection layer 534 as an electrode 502 to a thickness of 20 The deposition was carried out to obtain a thickness of 0 nm.

[0353] By the above steps, the structure formed on the substrate 520 was fabricated. In all steps, the deposition was carried out using a resistance heating method.

[0354] Next, in a glove box with a nitrogen atmosphere, a sealing material for organic EL is used to seal the substrate. The plate was fixed on the substrate 520 to seal the light emitting element. The substrate 520 and the sealing substrate are bonded together, and ultraviolet light with a wavelength of 365 nm is applied. 6J / cm 2 The light-emitting element 1 was obtained by the above steps. Ta.

[0355] <Fabrication of Light-Emitting Device 2> The fabrication of the light-emitting element 2 differs from that of the light-emitting element 1 described above only in the guest material, and the other steps The light-emitting element 2 was fabricated by the same method as that for the light-emitting element 1. TBP was used as a guest material for the light-emitting element 2.

[0356] That is, the light-emitting layer 521 of the light-emitting element 2 is made of a mixture of PCCzPTzn and 4,6mCzP2 The weight ratio of Pm and TBP (PCCzPTzn:4,6mCzP2Pm:TBP) is 0 The mixture was co-evaporated to a thickness of 30 nm in a ratio of 0.3:0.7:0.0025. In the light-emitting layer 521, PCCzPTzn is a thermally activated delayed phosphor (first organic compound ), 4,6mCzP2Pm is the host material (second organic compound), and TBP is the gate It is a steel material.

[0357] <Measurement of transient fluorescence characteristics> Here, in the light-emitting elements of this example (light-emitting element 1 and light-emitting element 2), The transient fluorescence properties of the PCCzPTzn used were measured by time-resolved luminescence measurement. .

[0358] For time-resolved luminescence measurements, PCCzPTzn was evaporated onto a quartz substrate to a thickness of 50 nm. The measurements were carried out using thin film samples prepared in a nitrogen atmosphere in a glove box. Then, a sealing substrate was fixed onto the quartz substrate on which the thin film sample was formed using an organic EL sealing material. Specifically, the thin film sample was sealed by sealing the thin film formed on the quartz substrate. A sealing material was applied, and the quartz substrate and the sealing substrate were bonded together. Then, ultraviolet light with a wavelength of 365 nm was applied for 6 J. / cm 2 The film was irradiated and then heat-treated at 80°C for 1 hour.

[0359] The measurements were performed using a picosecond fluorescence lifetime measurement system (Hamamatsu Photonics). To measure the lifetime of the fluorescence emitted by the thin film, the thin film was irradiated with a pulsed laser. The decaying light was then measured in time resolution using a streak camera. A nitrogen gas laser with a wavelength of 337 nm was used, and a pulse laser with a pulse width of 500 ps was used. The thin film is irradiated at a frequency of 0 Hz, and the S / N ratio is calculated by integrating the data measured repeatedly. The measurements were carried out at room temperature (23°C).

[0360] The transient fluorescence characteristics of PCCzPTzn obtained by the measurements are shown in FIG.

[0361] In addition, the attenuation curve shown in Figure 15 was fitted using the following equation (4): It was.

[0362]

number

[0363] In equation (4), L represents the normalized luminescence intensity, and t represents the elapsed time. As a result of fitting, fitting was possible for n from 1 to 3. From the fitting results of the decay curve, the emission components of the PCCzPTzn thin film sample include fluorescent It contains a fluorescent component with a light lifetime of 0.015 μs and a delayed fluorescent component with a light lifetime of 1.5 μs. PCCzPTzn is a thermally activated delayed fluorescent material that exhibits delayed fluorescence at room temperature. It was found that...

[0364] <Light-emitting element characteristics> Next, the current efficiency-luminance characteristics of the fabricated light-emitting elements 1 and 2 are shown in FIG. The external quantum efficiency vs. luminance characteristics are shown in Figure 17 and Figure 18, respectively. The optical element was measured at room temperature (an atmosphere maintained at 23°C).

[0365] Also, 1000 cd / m 2 The device characteristics of Light-Emitting Device 1 and Light-Emitting Device 2 in the vicinity are shown in Table 5. Shown below.

[0366] [Table 5]

[0367] Furthermore, 2.5 mA / cm 2 When a current is applied at a current density of The electroluminescence spectra are shown in FIG. 19. As can be seen from FIG. 19, the light-emitting elements 1 and 2 each exhibited It was found that blue light was emitted from the guest material.

[0368] As shown in FIGS. 16 to 18, the light-emitting elements 1 and 2 have low driving voltages. The device exhibited high luminous efficiency. In particular, the device 2 exhibited an external quantum efficiency exceeding 10% at maximum. The efficiency is shown in Fig. 1. A fluorescent material is used as the guest material, and only the energy from the singlet excited state is used. When using this for light emission, it is assumed that the light extraction efficiency from the inside of the light-emitting element to the outside is 25%. As a result, the external quantum efficiency of the light-emitting element is approximately 6% at most. The light-emitting devices 1 and 2, which contained the same material, showed higher external quantum efficiency. This is because the thermal activation delay The triplet excited state generated by the recombined carriers in the phosphor is converted into a triplet excited state by reverse intersystem crossing. This is because the electrons were converted into a singlet excited state.

[0369] In addition, in the light-emitting element 1 and the light-emitting element 2, as shown in Table 1 in the first embodiment, The HOMO of the thermally activated delayed fluorescent substance has an energy level equal to or higher than the HOMO of the host material. The LUMO of the thermally activated delayed fluorescent substance has an energy level below the LUMO of the host material. As shown in Table 2 in the first embodiment, the oxidation potential of the thermally activated delayed fluorescent substance is The oxidation potential of the thermally activated delayed fluorescent substance is equal to or lower than the oxidation potential of the host material. Since the reduction potential is higher than that of The HOMO of the thermally activated delayed fluorescent substance is the HO of the host material. The LUMO of the thermally activated delayed fluorescent substance has an energy level higher than the LUMO of the host material. It has an energy level lower than MO.

[0370] The triplet excited energy level of 1,6mMemFLPAPrn is expressed as The result of measurement using the same method as that shown in Fig. 1 was 1.84 eV. As shown in Table 3 of Form 1, the thermally activated delayed phosphor (PCCzPTzn The triplet excited energy levels of the guest material (4,6mCzP2Pm) and the host material (4,6mCzP2Pm) are is higher than the triplet excited energy level of

[0371] Therefore, in the light-emitting elements 1 and 2, the thermally activated delayed phosphor can efficiently emit light. The carriers recombine, and the energies of both the singlet and triplet excited states are Therefore, the light-emitting element 1 and the light-emitting device The optical element 2 has been shown to have high luminous efficiency.

[0372] Furthermore, since the light-emitting elements 1 and 2 exhibited high luminous efficiency, it was confirmed that the host material and the thermally activated The weight ratio of the host material to the thermally activated delayed phosphor (host material: thermally activated delayed phosphor) is 1:0.05 to 1:1. : 0.5, and the weight ratio of the host material to the guest material (host material:guest material) is A ratio of 1:0.001 to 1:0.01 was shown to be preferred.

[0373] As described above, by using the structure of one embodiment of the present invention, a light-emitting element having high emission efficiency can be obtained. can be produced. [Example]

[0374] In this example, a light-emitting device was compared with the presence or absence of a thermally activated delayed phosphor, and a light-emitting device was compared with the presence or absence of a host material and a guest material. Examples of fabricating light-emitting elements in which the weight ratio of the SiO2 material is changed (light-emitting elements 3 to 5) and comparative light-emitting elements 1 to 4). The schematic diagram is the same as that shown in FIG. 14 in Example 1. The light-emitting device fabricated in this example The details are shown in Tables 6 and 7. The structures and abbreviations of the compounds used are shown below. For other compounds, refer to the above-mentioned Embodiment 1 or Example 1.

[0375] [ka]

[0376] [Table 6]

[0377] [Table 7]

[0378] The methods for fabricating the light-emitting elements 3 to 5 and the comparative light-emitting elements 1 to 4 are described below. Show the law.

[0379] <Fabrication of Light-Emitting Device 3> On the substrate 520, ITSO was deposited by sputtering to a thickness of 110 nm as an electrode 501. The electrode area of the electrode 501 was 4 mm 2 (2mm x 2mm ) was decided.

[0380] Next, in order to form a light emitting element on the substrate 520, the surface of the substrate is washed with water as a pretreatment. After heat treatment at 200°C for 1 hour, UV ozone treatment was performed for 370 seconds.

[0381] Next, the substrate 52 on which the electrode 501 is formed is placed so that the surface on which the electrode 501 is formed faces downward. 0 to 1 x 10 -4 The substrate was fixed to a substrate holder installed in a vacuum deposition device whose pressure was reduced to about Pa. Then, a hole injection layer 531 was formed on the electrode 501 using DBT3P-II and MoO 3 and the weight ratio (DBT3P-II:MoO3) is 1:0.5 and the thickness is 7 The film was co-evaporated to a thickness of 0 nm.

[0382] Next, a hole transport layer 532 made of Cz2DBT was deposited on the hole injection layer 531 to a thickness of 20 nm. The vapor deposition was carried out as follows.

[0383] Next, a light-emitting layer 521 containing PCCzPTzn and CzDBT and 1,6mMemFLPAPrn in a weight ratio of (PCCzPTzn:Cz2DBT:1 ,6mMemFLPAPrn) is 0.1:0.9:0.005 and the thickness is 3 In the light-emitting layer 521, PCCzPTzn was co-deposited to a thickness of 0 nm. The compound is a delayed fluorescent substance (first organic compound), and Cz2DBT is a host material (second organic compound). (substance), and 1,6mMemFLPAPrn is the guest material.

[0384] Next, Bphen was deposited on the light-emitting layer 521 to form an electron transport layer 533 with a thickness of 30 nm. So, it was evaporated.

[0385] Next, LiF was deposited on the electron transport layer 533 to form an electron injection layer 534 with a thickness of 1 nm. The vapor deposition was carried out.

[0386] Next, Al was deposited on the electron injection layer 534 as an electrode 502 to a thickness of 200 nm. It was evaporated.

[0387] By the above steps, the structure formed on the substrate 520 was fabricated. In all steps, the deposition was carried out using a resistance heating method.

[0388] Next, in a glove box with a nitrogen atmosphere, a sealing material for organic EL is used to seal the substrate. The plate was fixed on the substrate 520 to seal the light emitting element. The substrate 520 and the sealing substrate are bonded together, and ultraviolet light with a wavelength of 365 nm is applied. 6J / cm 2 The light-emitting element 3 was obtained by the above steps. Ta.

[0389] <Fabrication of Light-Emitting Elements 4 and 5, and Comparative Light-Emitting Elements 1 to 4> The light-emitting elements 4 and 5 and the comparative light-emitting elements 1 to 4 are the light-emitting elements shown above. The only difference between the fabrication of the light-emitting element 3 and that of the light-emitting element 3 is the structure of the light-emitting layer, and the other steps are the same as those for the light-emitting element 3. did.

[0390] In the light-emitting element 4, the light-emitting layer 521 is made of a material including PCCzPTzn, Cz2DBT, and TBP. The weight ratio (PCCzPTzn:Cz2DBT:TBP) was 0.1:0.9:0.00 The luminescent layer 521 was co-deposited to a thickness of 30 nm. , PCCzPTzn is a thermally activated delayed phosphor (first organic compound), and Cz2DBT is The second organic compound is the host material, and the TBP is the guest material. The light-emitting element 4 is a light-emitting element having the same configuration as the light-emitting element 3 except for the guest material. be.

[0391] In the light-emitting element 5, the light-emitting layer 521 is made of a material including PCCzPTzn, CzTAZl, and TBP. The weight ratio (PCCzPTzn:CzTAZ1:TBP) was 0.1:0.9:0.00 The luminescent layer 521 was co-deposited to a thickness of 30 nm. , PCCzPTzn is a thermally activated delayed fluorescent substance (first organic compound), and CzTAZ1 is The second organic compound is the host material, and the TBP is the guest material. The light-emitting element 5 is a light-emitting element having the same configuration as the light-emitting element 4 except for the host material. be.

[0392] In the comparative light-emitting element 1, the light-emitting layer 521 is made of a compound of Cz2DBT and 1,6mMemFLPA. The weight ratio of Prn and Cz2DBT:1,6mMemFLPAPrn was 1:0.05. The co-deposition was carried out so that the thickness of the light-emitting layer 521 was 30 nm. z2DBT is the host material (second organic compound), and 1,6mMemFLPAPrn is That is, the comparative light-emitting element 1 contains a thermally activated delayed fluorescent material (first organic compound) as a guest material. It is a light-emitting element that does not use any organic EL material.

[0393] In the comparative light-emitting element 2, the light-emitting layer 521 is made of PCCzPTzn, Cz2DBT, and 1 ,6mMemFLPAPrn and, the weight ratio (PCCzPTzn:Cz2DBT:1,6m The ratio of MemFLPAPrn was 0.1:0.9:0.05 and the thickness was 30 nm. In the light-emitting layer 521, PCCzPTzn exhibits thermally activated delayed fluorescence. The photoconductor (first organic compound) and Cz2DBT are the host material (second organic compound). In other words, the comparative light-emitting element 2 has the following structure: The light-emitting element 3 has the same structure as the light-emitting element 1 except for the concentration of the guest material. be.

[0394] In the comparative light-emitting element 3, the light-emitting layer 521 is made of a material containing PCCzPTzn, Cz2DBT, and T The weight ratio of BP and CZPTzn:CZDBT:TBP was 0.1:0.9:0. The luminescent layer 521 was co-deposited to have a thickness of 30 nm. PCCzPTzn is the thermally activated delayed fluorescent substance (first organic compound), and Cz2DBT is the host material (second organic compound), and TBP is the guest material. The light-emitting element 3 has the same configuration as the light-emitting element 4, except for the concentration of the guest material. It is a light-emitting element.

[0395] In the comparative light-emitting element 4, the light-emitting layer 521 is made of a mixture of PCCzPTzn, CzTAZl, and T The weight ratio of BP and CzTAZ1 was 0.1:0.9:0. The luminescent layer 521 was co-deposited to have a thickness of 30 nm. PCCzPTzn is the thermally activated delayed fluorescent substance (first organic compound), and CzTAZ1 is the host material (second organic compound), and TBP is the guest material. The light-emitting element 4 has the same configuration as the light-emitting element 5, except for the concentration of the guest material. It is a light-emitting element.

[0396] <Light-emitting element characteristics> Next, the current efficiency-luminance of the fabricated light-emitting element 3, comparative light-emitting element 1, and comparative light-emitting element 2 was measured. The luminance characteristics are shown in Fig. 20, the current-voltage characteristics in Fig. 21, and the external quantum efficiency-luminance characteristics in Fig. 22. The light-emitting element 3, the comparative light-emitting element 1, and the comparative light-emitting element 2 were each supplied with 2.5 mA / cm². m 2 The electroluminescence spectrum when a current was passed at a current density of 1000 s is shown in FIG. 24 shows the current efficiency vs. luminance characteristics of the light-emitting element 4, the light-emitting element 5, the comparative light-emitting element 3, and the comparative light-emitting element 4. The current-voltage characteristics are shown in FIG. 25, and the external quantum efficiency-luminance characteristics are shown in FIG. 26. , 2.5 mA / cm for the light-emitting element 4, the light-emitting element 5, the comparative light-emitting element 3, and the comparative light-emitting element 4. 2 The electroluminescence spectrum when a current was passed at a current density of 1000 s is shown in FIG. The measurements were carried out at room temperature (an atmosphere maintained at 23°C).

[0397] Also, 100 cd / m 2 Light-emitting elements 3 to 5 and a comparative light-emitting element in the vicinity Table 8 shows the element characteristics of the light-emitting elements 1 to 4.

[0398] [Table 8]

[0399] 23 and 27, the emission spectra of the light-emitting elements 3 to 5 and the comparative light-emitting element Each of the light-emitting elements 1 to 4 emits blue light derived from the guest material. It can be seen that...

[0400] 20 to 22 and 24 to 26, the light emitting elements 3 to On the other hand, the comparative light-emitting elements 1 to 4 had sufficient luminescence efficiency. The light efficiency is not achieved.

[0401] The thermally activated delayed phosphor (PCCzPTzn) and host material (CzDB The results of measurements of the oxidation and reduction potentials of T or CzTAZ1 in solution and their implications The energy levels of the stacked HOMO and LUMO are shown in Table 9. is the same as the method shown in the first embodiment.

[0402] [Table 9]

[0403] As shown in Table 9, in the light-emitting elements 3 to 5, the oxidation electrode of the thermally activated delayed phosphor The oxidation potential of the thermally activated delayed fluorescent substance is equal to or lower than the oxidation potential of the host material. Since the reduction potential is higher than that of The HOMO of the thermally activated delayed fluorescent substance is at the energy level of the host material. The LUMO of the thermally activated delayed fluorescent substance has an energy level higher than the HOMO of the host material. Therefore, the thermally activated delayed fluorescent material has an energy level below the LUMO. The energy of the singlet and triplet excited states generated by carrier recombination is Both of them can efficiently transfer energy to the guest material. Light-emitting element 5 exhibits high luminous efficiency.

[0404] Furthermore, the light-emitting element 3 has higher luminous efficiency than the comparative light-emitting element 2. Since the luminous efficiency is higher than that of the optical element 1, PCC is used as a thermally activated delayed phosphor in the luminescent layer 521. It was found that the use of zPTzn improved the luminous efficiency. This was due to the thermal activation delay. In the phosphor PCCzPTzn, the triplet excited state generated is converted into This is because it is converted into a singlet excited state.

[0405] Furthermore, the light-emitting element 3 has higher luminous efficiency than the comparative light-emitting element 2; The weight of the host material (Cz2DBT) and guest material (1,6mMemFLPAPrn) in the The ratio (host material:guest material) is preferably 1:0.001 to 1:0.01. This is because the concentration of the guest material relative to the host material is sufficiently low. This is because the generation of triplet excited states of the guest material can be suppressed.

[0406] Similarly, the light-emitting element 4 has higher luminous efficiency than the comparative light-emitting element 3, and the light-emitting element 5 has higher luminous efficiency than the comparative light-emitting element 3. Since the luminous efficiency is higher than that of Device 4, the host material (Cz2DBT or The weight ratio of the host material (or CzTAZ1) to the guest material (TBP) (host material:guest material) was 1 It was found that a ratio of :0.001 to 1:0.01 was preferable.

[0407] Therefore, the weight ratio of the host material to the thermally activated delayed fluorescent substance (host material:thermally activated delayed fluorescent substance) The ratio of the host material to the guest material is preferably 1:0.05 to 1:0.5. The ratio of the host material to the guest material is preferably from 1:0.001 to 1:0.01. .

[0408] As described above, by using the structure of one embodiment of the present invention, a light-emitting element with high emission efficiency can be manufactured. It is possible. [Explanation of symbols]

[0409] 100 EL layer 101 Electrode 102 electrode 111 Hole injection layer 112 Hole transport layer 118 Electron transport layer 119 Electron injection layer 120 luminescent layer 131 Organic compounds 132 Organic compounds 133 Guest Materials 150 light-emitting elements 401 Electrode 402 Electrode 411 Hole injection layer 412 Hole transport layer 413 Electron transport layer 414 Electron injection layer 415 Hole injection layer 416 Hole transport layer 417 Electron transport layer 418 Electron injection layer 421 Organic compounds 422 Organic compounds 423 Guest Materials 431 Organic compounds 432 Organic compounds 433 Guest Materials 441 Lighting Unit 442 Lighting Unit 443 Light-emitting layer 444 luminescent layer 445 Charge generation layer 446 Lighting Unit 447 Lighting Unit 448 Light-emitting layer 449 Light-emitting layer 450 light-emitting elements 452 Light-emitting element 461 Host Materials 462 Guest Materials 471 Organic compounds 472 Organic compounds 473 Guest Materials 501 Electrode 502 Electrode 520 board 521 Light-emitting layer 531 Hole injection layer 532 Hole transport layer 533 Electron transport layer 533a Electron transport layer 533b Electron transport layer 534 Electron injection layer 801 pixel circuit 802 pixel section 804 Drive circuit section 804a Scanning line driving circuit 804b Signal line driver circuit 806 protection circuit 807 Terminal section 852 transistors 854 transistors 862 Capacitor element 872 Light-emitting element 2000 touch panel 2001 Touch Panel 2501 Display device 2502R pixels 2502t transistor 2503c Capacitive element 2503g(1) Scanning line driver circuit 2503t transistor 2509 FPC 2510 board 2510a Insulating layer 2510b flexible substrate 2510c adhesive layer 2511 Wiring 2519 terminal 2521 Insulation layer 2528 Bulkhead 2550R light emitting element 2560 Sealing layer 2567BM light shielding layer 2567p anti-reflection layer 2567R colored layer 2570 board 2570a Insulating layer 2570b flexible substrate 2570c adhesive layer 2580R Light Emitting Module 2590 board 2591 Electrode 2592 Electrode 2593 Insulation Layer 2594 Wiring 2595 Touch Sensor 2597 Adhesive layer 2598 Wiring 2599 Connection Layer 2601 Pulse voltage output circuit 2602 Current detection circuit 2603 Capacity 2611 Transistor 2612 transistor 2613 Transistor 2621 Electrode 2622 Electrode 8000 Display Module 8001 Top cover 8002 Lower cover 8003 FPC 8004 Touch Sensor 8005 FPC 8006 Display device 8009 Frame 8010 Printed Circuit Board 8011 Battery 8501 Lighting equipment 8502 Lighting equipment 8503 Lighting equipment 8504 Lighting equipment 9000 chassis 9001 Display section 9003 Speaker 9005 Operation key 9006 Connection terminal 9007 Sensor 9008 Microphone 9050 Operation button 9051 Information 9052 Information 9053 Information 9054 Information 9055 Hinge 9100 Mobile Information Terminal 9101 Mobile Information Terminal 9102 Mobile Information Terminal 9200 Mobile Information Terminal 9201 Mobile Information Terminal

Claims

1. A light-emitting layer is provided between a pair of electrodes, the light-emitting layer comprises a first organic compound capable of exhibiting thermally activated delayed fluorescence at room temperature, a second organic compound having one or more skeletons selected from a furan skeleton, a thiophene skeleton, a fluorene skeleton, and a pyrrole skeleton, and a guest material capable of exhibiting fluorescence; a HOMO level of the first organic compound has an energy level equal to or higher than a HOMO level of the second organic compound; A light-emitting device, wherein the LUMO level of the first organic compound has an energy level lower than the LUMO level of the second organic compound.

2. A light-emitting layer is provided between a pair of electrodes, the light-emitting layer comprises a first organic compound capable of exhibiting thermally activated delayed fluorescence at room temperature, a second organic compound having one or more skeletons selected from a furan skeleton, a thiophene skeleton, a fluorene skeleton, and a pyrrole skeleton, and a guest material capable of exhibiting fluorescence; an oxidation potential of the first organic compound is equal to or lower than an oxidation potential of the second organic compound; A light-emitting device, wherein the reduction potential of the first organic compound is equal to or higher than the reduction potential of the second organic compound.

3. In claim 1 or claim 2, The first organic compound has a first π-electron deficient heteroaromatic skeleton and a first π-electron rich heteroaromatic skeleton.

4. In claim 3, The light-emitting device, wherein the first π-electron rich heteroaromatic skeleton has one or more selected from an acridine skeleton, a phenoxazine skeleton, and a 3-(9-phenyl-9H-carbazol-3-yl)-9H-carbazole skeleton.

5. In claim 3 or claim 4, The light-emitting device, wherein the first π-electron-deficient heteroaromatic skeleton has a diazine skeleton or a triazine skeleton.

6. A light emitting device according to any one of claims 1 to 5; A display device having at least one of a color filter, a sealing material, and a transistor.

7. The display device according to claim 6 ; An electronic device having at least one of a housing or a touch sensor.

8. A light emitting device according to any one of claims 1 to 5; and at least one of a housing or a touch sensor.

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