Light-emitting device, display device, electronic device, and lighting 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. The present invention relates to a light-emitting device comprising the light-emitting element, and a display device, an electronic device, and a lighting device 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 object, a method, or a manufacturing method. One aspect of the present 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 of the present invention, 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 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 element has a pair of electrodes and a layer containing a light-emitting substance (EL layer) 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 the light-emitting element has excellent visibility and backlighting. It has the advantage of not requiring a light source and consuming little power. It also has the advantage of having a high response speed.

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

[0006] The types of excited states that organic materials can form include singlet excited states (S 1 ) and triplet excited states state(T 1 ) emission from the singlet excited state is fluorescence, and emission from the triplet excited state is phosphorescence. The statistical generation ratio of these in a light-emitting element is called S 1 :T 1 =1 Therefore, it is more efficient 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 having a triplet excited state can achieve a higher light-emitting 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 a portion of the triplet excited state into luminescence have been developed that have thermal activation delay Thermally activated delayed fluorescence Thermally activated delayed fluorescent materials are known to emit light in the triplet excited state. A singlet excited state is generated by intersystem crossing, and the singlet excited state is converted into light emission. 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, The advantage is that the singlet excited state can be efficiently used for luminescence, i.e., the fluorescence quantum yield is high. However, it is difficult to design a light-emitting material that satisfies both of these requirements at the same time. do.

[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 substance is transferred to a fluorescent material, which emits fluorescence. A method for obtaining light emission from a material having such a property has been proposed (see Patent Document 3). [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2004-241374 A [Patent Document 2] JP 2006-24830 A [Patent Document 3] JP 2014-45179 A 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 material that emits fluorescence, the luminous efficiency is In order to increase the photoluminescence intensity, 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. It is important that energy is transferred.

[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 having 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 objective is to provide a novel light-emitting element with high emission 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 may be solved by the specification. The above problems are obvious from the description of the specification, etc., and 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, wherein the EL layer comprises 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 including a pair of electrodes and an EL layer provided between the pair of electrodes. The EL layer is a light-emitting element having a first organic compound, a second organic compound, and a guest and a material, the first organic compound having 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 is 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 potential of the organic compound of formula 2 is equal to or higher than the reduction potential 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 between the excitation energy level and the excitation 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, 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:

[0020] In each of the above 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 The weight ratio of the second organic compound to the guest material (second organic compound:guest material) is from 1:0.001 to 1: It is preferably 0.01.

[0021] Another embodiment of the present invention is a light-emitting element having any of the above structures, and a color filter, a seal, or Another embodiment of the present invention is a display device including the display device. The electronic device according to the present invention 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. It is. Effect of the Invention

[0022] According to one embodiment of the present invention, there is provided a light-emitting element having a fluorescent material as a light-emitting material, 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 having high emission efficiency can be provided. According to one embodiment of the present invention, a light-emitting element with high light-emitting performance and high reliability can be provided. A novel light-emitting element having high emission efficiency can be provided. It is possible to provide a novel light-emitting element with low power consumption.

[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 become apparent from the description in the specification, drawings, claims, etc. It is possible to extract other effects from the descriptions in the claims, etc. [Brief description of the drawings]

[0024] [Figure 1] 1 is a schematic cross-sectional view illustrating a light-emitting element of one embodiment of the present invention. [Diagram 2] 1A and 1B are diagrams illustrating the correlation of energy levels in a light-emitting element according to one embodiment of the present invention. [Diagram 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. [Diagram 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] 1 is a cross-sectional view illustrating an example of a display device and a touch sensor according to one embodiment of the present invention. [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 are diagrams illustrating a lighting device according to one embodiment of the present invention. [Figure 14] 1 is a schematic cross-sectional view illustrating a light-emitting element according to Examples 1 and 2. FIG. [Figure 15] FIG. 4 is a diagram illustrating the transient fluorescence characteristics of a host material in Example 1. [Figure 16] FIG. 2 is a graph showing current efficiency vs. luminance characteristics of a light-emitting element in accordance with Example 1. [Figure 17] FIG. 4 is a graph showing current-voltage characteristics of the light-emitting element in the first embodiment. [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 an electroluminescence spectrum of a light-emitting element according to Example 1. [Figure 20] FIG. 13 is a graph showing current efficiency vs. luminance characteristics of a light-emitting element according to Example 2. [Figure 21] FIG. 11 is a graph showing current-voltage characteristics of a light-emitting element according to Example 2. [Figure 22] FIG. 11 is a graph showing the external quantum efficiency-luminance characteristics of a light-emitting element according to Example 2. [Figure 23] FIG. 13 is a graph showing an electroluminescence spectrum of a light-emitting element according to Example 2. [Figure 24] FIG. 13 is a graph showing current efficiency vs. luminance characteristics of a light-emitting element according to Example 2. [Diagram 25] FIG. 11 is a graph showing current-voltage characteristics of a light-emitting element according to Example 2. [Figure 26] FIG. 11 is a graph showing the external quantum efficiency-luminance characteristics of a light-emitting element according to Example 2. [Figure 27] FIG. 13 is a graph showing an electroluminescence spectrum of a light-emitting element according to Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, the embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the above description, and the embodiments and details thereof are not limited to those described above without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the embodiments described below. 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 are not necessarily shown in order to facilitate understanding. The actual position, size, range, etc. may not be shown. The present invention is not necessarily limited to the position, size, range, etc. disclosed in the drawings, etc.

[0027] In addition, in this specification, ordinal numbers such as 1st, 2nd, etc. are used for convenience. For example, "first" may be replaced with "second" and not indicate the order of steps or stacking. In addition, the terms "the" or "the third" may be used interchangeably in the description of the present specification. 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.

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

[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. Also, S 1 The level is the lowest singlet excited energy level and is the The excited energy level of the singlet excited state is the lowest. The triplet excited state is the highest excited The triplet state has energy. Also, T 1The level is the 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 in the case of 1 It can also represent the level of Even when expressed as singlet and triplet excited energy levels, the lowest triplet Term excited states and T 1 It may represent a level.

[0031] In the present specification and the like, the term "fluorescent material" refers to a material that emits light at the lowest level of the singlet excited state (S 1 Rank) A phosphorescent material is a material that emits light in the visible light region when it relaxes from the triplet state to the ground state. The lowest excited state (T 1 When the electron relaxes from the 100-nm level 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 light. It is one of the materials that can be converted into visible light.

[0032] In the present 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 material refers to a material 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 combination of two materials may 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 light with a wavelength of 0.2 eV or less, such as TADF, are preferred. In a material that can generate a singlet excited state from a triplet excited state by reverse intersystem crossing, The difference in energy levels between the doublet excited state and the singlet excited state is greater than 0 eV and is 0.2 eV or less. Or the difference in energy between the triplet excited state and the singlet excited state in the exciplex is 0e It is preferable that the difference is greater than V and is 0.2 eV or less.

[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 emission energy or triplet excitation energy is the phosphorescence energy on the shortest wavelength side of phosphorescence emission. The emission peak (including the shoulder) is the emission peak. Note that the above phosphorescence emission is observed at low temperatures (for example, 10K ) environment, it can be observed by time-resolved photoluminescence. .

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

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

[0037] <1. Example of the configuration of the light-emitting element> First, a 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 composition of 50 may be reversed.

[0039] The EL layer 100 shown in FIG. 1A includes a functional layer in addition to the light-emitting layer 120. The layers are 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. A layer selected from the group consisting of the hole transport layer 111, the hole transport layer 112, the electron transport layer 118, and the electron injection layer 119. Alternatively, the EL layer 100 may have a hole or electron injection 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 suppressing the quenching phenomenon caused by the electrode. It may also be configured as follows.

[0040] FIG. 1B is a schematic cross-sectional view showing an example of the light-emitting layer 120 shown in FIG. The light-emitting layer 120 shown in FIG. 1B is made of 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 phosphor 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 is 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 the organic compound 131. The difference is preferably greater than 0 eV and less than or equal to 0.2 eV. The excitation energy level is higher than the singlet excitation energy level of the guest material 133, and the organic The triplet excited energy level of compound 131 is higher than the singlet excited energy level of guest material 133. In this way, the triplet excitation energy of the organic compound 131 is preferably higher than the above. The energy level can be brought closer to the singlet excited energy level.

[0042] The organic compound 132 is preferably selected from the group consisting of organic compounds 131 and guest materials 133. A material with a large band gap is preferred. That is, the singlet excitation energy of the organic compound 132 is The energy levels are higher than the singlet excited energy levels of the organic compounds131 and guest materials133. 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 be further included in the light-emitting layer 120. It is okay if it is.

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

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

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

[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 material> First, to explain the direct recombination process in the guest material 133, the energy The following is a schematic diagram for explaining the correlation of 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 excited energy level of organic compound 131 ·S H : The lowest singlet excited 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 recombines with the ions, an excited state of the guest material 133 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) described above, 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 light 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), E 1 As shown in the figure, the singlet excitation energy of organic compound 131 is S AFrom guest material 133 S G The guest material 133 enters the singlet excited state. The guest material 133 in the singlet excited state emits fluorescent light.

[0052] In addition, 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. In other words, as shown in the following general formula (G1), the singlet excited state of the organic compound 131 is From this viewpoint, 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 compound 131 and gelatin, 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 the excited state is a triplet excited state, Fluorescence emission is obtained through two processes.

[0056] Since organic compound 131 is a thermally activated delayed fluorescent material, the first step is shown in Figure 2(B). Root A 1 As shown in the figure, the TA from reverse intersystem crossing (upconvergence By S A Excitation energy is transferred to

[0057] The second step is the synthesis of organic compound 131, S A However, the guest material 133 S G If it is higher than 1, then route E in Figure 2(B) 1 As shown in the figure, the S A Karaage Stove 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 organic compound 131 and guest material 133, respectively. Represents the bottom state.

[0061] As shown in the general formula (G2), the triplet excitation of the thermally activated delayed fluorescent organic compound 131 was Waking state ( 3 A * ) to the singlet excited state of organic compound 131 ( 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 (β) thermally activated delayed fluorescent substance mentioned above If the transfer process occurs efficiently, the triplet excitation energy and singlet excitation energy of organic compound 131 will be Both the energy and the excited state of the guest material 133 are efficiently excited ( 1 G * ) This enables 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 ions are released and deactivated, the luminescence efficiency will decrease. As a result, in organic compound 131, reverse intersystem crossing occurs from the triplet excited state to the singlet excited state. Route A 1 If the efficiency of the process is reduced, the light emission 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 the Root A of 2(B) 1 Since reverse intersystem crossing of is difficult to occur, the following route E1 Shown in The efficiency of the energy transfer process also decreased, and the generation efficiency of the singlet excited state of the guest material 133 became low. 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 It is preferable that the phosphorescence emission energy of the photoresist material 133 be higher than that of the photoresist material 133 .

[0064] At this time, route E in Figure 2(B) 2 As shown in the figure, the T A From guest material Fee 133 T G When excitation energy is transferred to the Therefore, route E in Figure 2(B) 2 The fewer the energy transfer processes shown in 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, the ratio is from 1:0.001 to 1:0.05, and more preferably from 1:0.001 to The ratio is 1:0.01.

[0065] In addition, when the direct recombination process in the guest material 133 becomes dominant, the guest A large number of triplet excited states are generated in the material 133, 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 terbium oxide material 133 can be reduced, and the thermal loss of the excitation energy can be reduced. This is preferable because it can reduce the activity of the organic compound 131 and the It is preferable that the weight ratio of the host material 133 is low compared to 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 showing the correlation of energy levels is shown in Figure 2(C). The notations and symbols in Figure 2(C) are the same as those in Figure 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, organic compound 131 S A and S of guest material 133 G If it is higher than Organic Compound 132 S H From the guest material 133, S G The singlet excitation energy is transferred to Or, S of organic compound 132 H From organic compound 131 S A Singlet excitation transferred to The energy is transferred from the thermally activated delayed fluorescent material (β) to the nucleus via the energy transfer process. , S of guest material 133 G The energy is transferred to the guest material 1 in the singlet excited state. In this embodiment, the organic compound 132 is used as a host material. This is explained as follows.

[0068] In addition, 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 indirect transition is forbidden, it is unlikely to be the main energy transfer process. In other words, 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, and1 G is 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 the organic compound 132 is generated and it is a triplet excited state, Compound 132 T H is the T of organic compound 131 A Higher, organic compound 131 S A But, Stove material 133 S G When the concentration is higher than 100, the following process occurs to obtain fluorescent emission:

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

[0074] The next 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 A 1 ) and the organic compound 131 S A From guest material 133 S G Energy The guest material 133 moves and enters a singlet excited state, from which fluorescence is emitted.

[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 chemical compounds 133, respectively. represents the triplet excited state of the 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, which then rapidly undergoes reverse intersystem crossing to The singlet excited state of organic compound 131 ( 1 A * ) is generated, and then the guest material 133 Singlet excited state ( 1 G * ) energy is transferred 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 can be - and the singlet excited state of the guest material 133 ( 1 G * ), so This allows light to be emitted from the photoresist 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 If the photocatalyst is deactivated by releasing heat, the luminous efficiency will decrease. In the organic compound 131, the reverse intersystem transition from the triplet excited state to the singlet excited state is Intersecting Route A 1 If the efficiency of this 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 the Since reverse intersystem crossing does not occur in the organic compound 131, the singlet excitation of the guest material 133 is prevented. Therefore, the efficiency of generating the excited state is reduced. H Organic Compound 131 T A It is preferable that it is higher than .

[0081] Also, route E in Figure 2(C) 3 As shown in the figure, the T H From guest material 133T G When excitation energy is transferred to the So, route E in Figure 2(C) 3 The fewer the energy transfer processes shown in Fig. 13, the more the guest material 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 material 133 is low. The weight ratio of organic compound 132 to guest material 133 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 excited energy A part of the energy is converted into the fluorescent emission of the guest material 133, but the 2 oh Yobi E 3 Therefore, the thermal deactivation from the (γ) host material 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 ratio of the energy transfer process from the thermally activated delayed phosphor, the higher the energy transfer efficiency in the light-emitting layer 120. In other words, the thermal deactivation can be reduced. This is preferable because it is possible to increase the luminous efficiency of the light emitting element 150. In order to increase the proportion 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 compound 132 is important. In particular, the highest occupied molecular orbital (H ighest occupied molecular orbital, also known as HOMO Lowest Unoccupied Molecular Orbital (Lowest Unoccupied Molecular Orbital) The relationship between the energy levels of the rbital and the LUMO, or the oxidation potential and reduction potential The relationship with electric potential is important.

[0084] When carriers are injected from a pair of electrodes into the EL layer 100 and reach the light-emitting layer 120, Carriers are injected into the material that constitutes 20. At this time, a hole is injected into the more stable HOMO, Therefore, the organic compound that is a thermally activated delayed fluorescent material is more likely to have an electron enter 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 equal to or higher than the HOMO of organic compound 132, and the LUM of organic compound 131 It is important that O has an energy level equal to or lower than 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 achieved. It is possible to provide a structure in which a complex is unlikely to be formed.

[0086] In addition, when the molecules of the organic compound 131 are adjacent to each other in the light-emitting layer 120, carriers are generated. In that case, the organic compound 131 can move between molecules easily. For example, carriers may be easily transported 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. In order to achieve this, the weight ratio of organic compound 132 to organic compound 131 must be The lower the ratio, the more preferable. In addition, the excited state molecules and ground state molecules of the organic compound 131, 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 the molecules of the organic compound 131 and the photocatalyst material 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 governing 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 energy transfer process between the molecules of the material 133 is explained. The same applies to the intermolecular energy transfer process between the guest material 133 and the cation exchange layer 134 .

[0088] <Förster mechanism> In the Förster mechanism, the energy transfer does not require direct contact between molecules. 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 goes to the ground state, and the guest material 13 3 becomes excited. The rate constant of the Förster mechanism is kh*→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 (fluorescence spectrum when discussing energy transfer from a singlet excited state) is calculated. spectrum when discussing energy transfer from triplet excited states), ε g (ν) represents the molar extinction coefficient of the guest material 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 is the measured lifetime of the excited state (fluorescence lifetime or phosphorescence lifetime) and c is the speed of light. , φ is the emission quantum yield (or the fluorescence quantum yield when considering energy transfer from a singlet excited state) When discussing energy transfer from a triplet excited state, it is the phosphorescence quantum yield, and when discussing energy transfer from a triplet excited state, it is the phosphorescence quantum yield, and K 2 teeth , a coefficient (between 0 and 131) that represents the orientation of the transition dipole moment of the organic compound 131 and the guest material 133 In the case of random orientation, K 2 =2 / 3.

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

[0092]

number

[0093] In formula (2), h is the Planck constant, and K is a constant with the dimension of energy. where ν is the frequency and f' is the h (ν) is the normalized emission spectrum of 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 the term fluorescence. When discussing energy transfer from triplet excited states, we use the term phosphorescence. light), and k n is the non-radiative process (thermal deactivation and intersystem crossing) of organic compound 131. represents the rate constant, and τ represents the measured lifetime of the excited state of the organic compound 131.

[0095]

number

[0096] From equation (3), the energy transfer efficiency φ ET To increase the rate of energy transfer, Degree constant k h*→g By increasing the other competing rate constants k r +k n(=1 / τ) is relatively It turns out that the smaller it is, the better.

[0097] <Concept for improving 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 reaction mechanism (Equation (2)) and the reaction mechanism (Equation (3)).

[0098] First, consider the energy transfer via the Förster mechanism. From equations (1) and (3), Eliminating τ gives 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 (singlet excited state or The energy transfer from the guest material is discussed, so the fluorescence spectrum and the absorption spectrum of the guest material are (absorption corresponding to the transition from the singlet ground state to the singlet excited state) 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 that appears on the longest wavelength side are shown in Fig. This means that it overlaps with the harvest.

[0099] Next, consider the energy transfer via the Dexter mechanism. According to equation (2), the rate constant is k h*→g In order to increase the emission spectrum of 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 see good things.

[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 transfer system capable of efficiently transferring energy to the guest material 133. The present invention provides a light-emitting element using an organic compound 131 having a function as an electron donor. Since the organic compound 131 is a thermally activated delayed fluorescent substance, it has a singlet excited energy level and a triplet excited energy level. The first excited energy level is close to the first excited energy level. 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. A transition from the excited state to the singlet excited state (reverse intersystem crossing) is likely to occur. In addition, 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 the light-emitting element 150 of one embodiment of the present invention, the HOMO of the organic compound 131 is The HOMO of organic compound 132 is equal to or higher than the LUMO of organic compound 131. has an energy level equal to or lower than the LUMO of organic compound 132, or The oxidation potential of organic compound 132 is equal to or less than the oxidation potential of organic compound 132, 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 is not observed. 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: There can be.

[0105] First, there are fullerene and its derivatives, acridine derivatives such as proflavine, and eosin. In addition, magnesium (Mg), zinc (Zn), cadmium (Cd), and tin (Sn) Metal-containing polyimide including platinum (Pt), indium (In), or palladium (Pd) Examples of the metal-containing porphyrin include porphyrin represented by the following structural formula: The protoporphyrin-tin fluoride complex (SnF 2 (Proto IX), Mesopotamus Lufirin-Tin Fluoride Complex (SnF 2 (Meso IX)), hematoporphyrin- Tin fluoride complex (SnF2 (Hemato IX)), coproporphyrin tetramethyl ether Sten-Tin Fluoride Complex (SnF 2 (Copro III-4Me)), octaethylpoly Luphirin-Tin Fluoride Complex (SnF 2 (OEP)), etioporphyrin-tin fluoride Complex (SnF 2 (Etio I)), octaethylporphyrin-platinum chloride complex (PtC l 2 OEP) etc.

[0106] [ka]

[0107] As the organic compound 131, 2-(biphenyl-4-phenyl)-2-phenylpropanediol having the following structural formula is used. 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 1,2-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. Since 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 skeleton) is preferred. The azine, pyrazine, pyridazine, or triazine skeletons are stable and reliable. In addition, 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 Since the (-yl)-9H-carbazole skeleton is stable and has good reliability, 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. The donor and π-electron-deficient heteroaromatic rings have strong acceptor properties, and the singlet excited state level This is particularly preferable because the difference in the energy level between the triplet excited state and the triplet excited state becomes 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 skeletons that easily receive electrons (skeleton with electron transport properties) and skeletons that easily receive holes. It is preferable that the cyclic structure has either one or both of the following: stomach.

[0110] Compounds that have a skeleton that easily accepts electrons (skeleton with electron transport properties) include π electrons Compounds having a deficient heteroaromatic skeleton and metal complexes 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 the above structure and 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo 2-[3'-(diphenylphosphine) (4-phenyl-4-yl)biphenyl-3-yl)dibenzo[f,h]quinoxaline (abbreviation Name: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl 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- 35DCzPPy, 1,3,5-Triphenyl-9-yl)pyridine Pyridine skeleton such as tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB) Among the above-mentioned heterocyclic compounds, diazines (pyridyl) Heterocyclic compounds having a pyridine skeleton or a pyridine skeleton are stable. In addition, the heterocyclic compound having the above skeleton has an electron transporting property. This also contributes to reducing the driving voltage.

[0111] Compounds having a skeleton that easily receives holes (skeleton with hole transport properties) include π-electrolyte Compounds having a molecular-rich heteroaromatic skeleton or an aromatic amine skeleton 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 S(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 ( Abbreviated name: 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'-bifluorene-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 carbazole skeletons Compounds that cause 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzo thiophene) (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl (abbreviation: DBTFL) P-III), 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]- Thiophene skeleton such as 6-phenyldibenzothiophene (abbreviation: DBTFLP-IV) Compounds having the structure 4,4',4''-(benzene-1,3,5-triyl)tri(diphenyl Zofran) (abbreviation: DBF3P-II), 4-{3-[3-(9-phenyl-9H-fluoro oren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi- II) and other compounds having a furan skeleton. 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 of the following properties have high carrier transport properties: This contributes to reducing the driving voltage. In addition, the compound having this skeleton has 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 compound 131 and the organic compound 132 are not limited to the above-mentioned compounds. The HOMO of organic compound 131 has an energy level higher than that 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 greater than or equal to the oxidation potential of organic compound 13 The oxidation potential of organic compound 2 is equal to or less than the reduction potential of organic compound 131, and the reduction potential of organic compound 132 is equal to or less than the reduction potential of organic compound 133. The combination is as above, and other materials may be used as long as the carrier can be transported. In addition, a thermally activated delayed fluorescent material may be used for the organic compound 132 .

[0114] As an example of a compound that can be used for the above organic compound 131 and organic compound 132, The results of the measurement of the HOMO and LUMO energy levels in each thin film state are shown in Fig. The results of the measurement of the oxidation potential and reduction potential in the solution state and the estimation of the potential are shown in Fig. 1. The HOMO and LUMO energy levels are shown in Table 2. The results of the measurements 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 is determined by the ionization potential of each compound. The ionization potential was measured in air using photoelectron spectroscopy (Riken Keiki, AC-3). The absorption spectrum of each compound in the thin film state was calculated by converting the valence value of the compound into a negative value. The absorption edge is calculated from the Tauc plot assuming a direct transition. The optical band gap of the ZnO-doped ... 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 and reduction properties) of each compound in solution were measured. The measurements were performed by cyclic voltammetry (CV). A analyzer (manufactured by BAS Co., Ltd., model number: ALS model 600A or 600C) In the measurement, the potential of the working electrode relative to the reference electrode was changed in an appropriate range to measure the amount of each acid. The redox potential of the reference electrode was -4 0.94 eV, so from this value and the obtained peak potential, The HOMO and LUMO energy levels of the compounds were calculated.

[0121] The triplet excitation energy levels of each compound were measured by phosphorescence measurement. 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 triplet excitation was determined from the shortest wavelength peak in the phosphorescence spectrum obtained from the measurement. The excitation energy levels were calculated.

[0122] As an example, in Tables 1 and 2, the HOMO of organic compound 131 is the same as that of organic compound 13. The HOMO of organic compound 2 is higher than that of organic compound 1, and the LUMO of organic compound 131 is higher than that of organic compound 1. Use compounds with combinations that have an energy level below the LUMO of 32, or is that the oxidation potential of organic compound 131 is equal to or lower than the oxidation potential of organic compound 132, and The reduction potential of the organic compound 131 is higher than or equal to the reduction potential of the organic compound 132. As a result, the carriers injected into the EL layer 100 are efficiently transported through the organic compound 131. Since electrons can be easily recombined, 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 useful. Using compounds that have a combination that is higher than the triplet excited energy level 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. Energy transfer to the excited energy level is more likely to occur. This facilitates the energy transfer process from the photocatalyst 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 and phenothiazine derivatives are preferred. For example, the following materials are used: 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 1,6-Pyrene-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn) , N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H -fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMem FLPAPrn), N,N'-bis[4-(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-tetradecane 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 N,9-diphenyl-N-[4-(9,10-diamine] (abbreviation: DPABPA), 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-cal 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 Chil-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinoli 4H-pyran-4-ylidene)propanedinitrile (abbreviation) :DCM2), N,N,N',N'-tetrakis(4-methylphenyl)tetracene-5 ,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N',N '-Tetrakis(4-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}propanidine DCJTI, 2-{2-tert-butyl-6-[2-(1,1,7,7 -Tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolidine 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: BisDCJTM), 5,10,1 5,20-Tetraphenylbisbenzo[5,6]indeno[1,2,3-cd:1',2 ',3'-lm]perylene, and the like.

[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 ( The absorption corresponds to the transition from the singlet ground state to the singlet excited state of the guest material 133. As long as the material satisfies the requirements, other materials may also be used.

[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] The electrode 101 and the electrode 102 have a 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 aluminum, and other materials can be used. transition metals such as silver, tungsten, chromium, molybdenum, copper, and titanium; lithium and cesium Alkali metals such as tungsten, calcium, magnesium, and other group 2 metals 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. The conductive compound is indium oxide-tin oxide (InTinOxide). Examples of conductive compounds include inorganic compounds such as graphene. Carbon-based materials may also be used. As described 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.

[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. It transmits light. 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 with 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 01 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 esters have the function of promoting the formation of the aryl group. The transition metal oxides are formed by molybdenum oxide and vanadium oxide. oxide, ruthenium oxide, tungsten oxide, manganese oxide, etc. Examples of the phthalocyanine derivatives include phthalocyanine and metal phthalocyanine. Examples of the aromatic amine include benzidine derivatives and phenylenediamine derivatives. Polymer compounds such as polythiophene and polyaniline can also be used. Poly(ethylenedioxythiophene) / poly(styrenesulfonyl)sulfate sulfonic acid) are typical examples.

[0132] The hole injection layer 111 is made of a compound of a hole transporting material and a material that has an electron accepting property. Alternatively, a layer containing a material exhibiting electron accepting properties and a layer containing a positive electrode may be used. A stack of layers containing hole transporting materials may also be used. It is possible to give and receive electric charges in the presence of a magnetic field. Materials that exhibit electron-accepting properties include quinodimethane. Organic acceptors such as aryl, chloranil, and hexaazatriphenylene derivatives Specifically, 7,7,8,8-tetracyano-2,3,5,6- Tetrafluoroquinodimethane (abbreviation: F 4 -TCNQ), chloranil, 2,3,6,7, 10,11-Hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation These are compounds that have electron-withdrawing groups (halogen groups or cyano groups) such as aryloxycarbonyl (HAT-CN). In addition, transition metal oxides, for example oxides of metals in Groups 4 to 8, can be used. In particular, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, and oxide These include tungsten oxide, manganese oxide, and rhenium oxide. Among these, molybdenum oxide is Among these, it is preferred because it is stable, has low hygroscopicity, and is easy to handle.

[0133] As the hole transporting material, a material having a higher hole transporting property than an electron transporting property can be used. ×10 -6 cm 2 It is preferable that the material has a hole mobility of 1 / Vs or more. The compounds are made using aromatic amines, carbazole derivatives, aromatic hydrocarbons, stilbene derivatives, etc. 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 transporting material. The hole transport layer 112 can be formed by injecting the hole into the hole injection layer 111. Since the hole-injection layer 111 has a function of transporting the holes to the light-emitting layer 120, the HOMO of the hole-injection layer 111 is the same as that of the hole-injection layer 111. It is preferred that the HOMO energy level is equal to 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 transport material, it has a function of transporting electrons to the electron transport region 120. The material can be easily used, and the 1×10 -6 cm 2 Materials with electron mobility of ≥ 1000V Specifically, quinoline ligands, benzoquinoline ligands, oxazololide ligands, Metal complexes with triazole or thiazole ligands, oxadiazole derivatives, triazole derivatives, Examples include azole derivatives, phenanthroline derivatives, pyridine derivatives, and bipyridine derivatives. In addition, the organic compound 132, which has a skeleton that easily accepts electrons, 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 above-mentioned electron transporting material and the corresponding electron A composite material of a material exhibiting electron donating properties can also be used. Examples of the metal include Group 1 metals, Group 2 metals, and oxides thereof.

[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 inkjet method, a coating method, a grating method, or the like. The film can be formed by a method such as rabbet printing.

[0138] In addition, the hole injection layer 111, the hole transport layer 112, the light emitting layer 120, the electron transport layer 118, and In addition to the above-mentioned materials, the electron injection layer 119 may be made of 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 that order.

[0140] The light emitting element 150 can be formed on a substrate such as glass, quartz, or plastic. A flexible substrate may be used. A flexible substrate is a material that can be used for a wide range of applications, such as polycarbonate, polyamide, etc. Examples of the substrate include a plastic substrate made of a film or an inorganic deposition film. In the manufacturing process of the light-emitting element and the optical element, As long as it functions as a light emitting element, it may be any other 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 substrate). crystal substrate or silicon substrate), SOI substrate, glass substrate, quartz substrate, plastic substrate, gold Metallic substrate, stainless steel substrate, substrate with stainless steel foil, tungsten Tungsten substrate, substrate with tungsten foil, flexible substrate, laminated film, fiber Examples of substrates include paper or base films containing barium-based materials. Borosilicate glass, aluminoborosilicate glass, or soda-lime glass are available. 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) As an example, there are plastics such as acrylic resins. Alternatively, for example, polypropylene, polyester, polyvinyl fluoride, or poly Examples include polyamide, polyimide, aramid, and ethylene. Examples of the material include epoxy, inorganic vapor deposition film, and paper.

[0142] In addition, a flexible substrate may be used as the substrate, and the light emitting element may be formed directly on the flexible substrate. Alternatively, a release layer may be provided between the substrate and the light-emitting element. After a part or all of a chip is completed, it is separated from the board and used to transfer it to another board. In this case, the light-emitting element can be transferred onto a substrate having poor heat resistance or a flexible substrate. The above-mentioned peeling layer has a laminated structure of inorganic films, for example, a tungsten film and a silicon oxide film. or a structure in which a resin film such as polyimide is formed on a substrate.

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

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

[0145] Note that one embodiment of the present invention has been described in this embodiment. In the following, one embodiment of the present invention will be described. However, the embodiment of the present invention is not limited to these. 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 not known. The oxidation potential of organic compound 132 is equal to or less than the reduction potential of organic compound 131. However, one embodiment of the present invention is not limited thereto. 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 equal to or 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 less than or equal to the reduction potential of organic compound 132. For example, in one embodiment of the present invention, the organic compound 131 may have a potential of In the above, an example was shown in which 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 have any other substance than the substance that exhibits thermally activated delayed fluorescence at room temperature. Alternatively, depending on the circumstances, in one aspect of the present invention, For example, the organic compound 131 does not need to have 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, an organic The weight ratio of compound 132 to organic compound 131 is not necessarily low. good.

[0146] 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 described below with reference to FIGS.

[0148] <Example of the configuration 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 which , a plurality of light-emitting units (in FIG. 3A, 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 In the light-emitting element 450, the electrode 401 serves as an anode. 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. The light-emitting units 441 and 442 are laminated, and a charge generating layer 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 an EL layer 100 shown in FIG. It is preferable to use a light-emitting layer having a phosphorescent material as a 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 hole injection layer 411, a hole transport layer 412, an electron The light-emitting unit 442 also 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 generating layer 445 includes 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 the organic material include an aromatic amine compound and a carbazole compound. , aromatic hydrocarbons, polymer compounds (oligomers, dendrimers, polymers, etc.), etc. The organic material can be a compound having a hole mobility of 1×10 -6 c m 2 However, it is preferable to use a material having a hole transport property rather than an 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-current operation. In addition, as in the light-emitting unit 442, the positive electrode of the light-emitting unit can be driven by the positive electrode. When the polar surface is in contact with the charge generating layer 445, the charge generating layer 445 is the positive electrode of the light emitting unit. Since it can also play the role of a hole injection layer or a hole transport layer, the light-emitting unit has a hole injection 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 having an electron accepting property, It may be formed as a laminated structure combining layers made of other materials. For example, A layer including a composite material of an organic material and a material exhibiting electron accepting property, and a layer including a composite material of an organic material and a material exhibiting electron donating property A layer containing one of the materials selected from the above and a material having a high electron transporting property may be combined to form the layer. 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 It may be formed by combining and.

[0154] The charge generating layer 445 sandwiched between the light emitting unit 441 and the light emitting unit 442 is an electrode When a voltage is applied between the electrode 401 and the electrode 402, electrons are injected into one of the light-emitting units and 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 having three or more stacked light-emitting units. As shown in the light-emitting element 450, a plurality of light-emitting units are electrically connected between a pair of electrodes. By separating the layers, it is possible to emit high-intensity light while keeping the current density low. Furthermore, it is possible to realize a light-emitting element having a long life. Also, it is possible to realize a light-emitting element having low power consumption. can.

[0156] At least one of the multiple units includes 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 the present 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 gel contained in the light-emitting layer 443 are The resist material 423 is a mixture of the organic compound 131, the organic compound 132, and the gate electrode 423 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. The electrode 401, the electrode 402, the hole injection layer 411, and 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 similar to that 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 an electron transporting property.

[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 FIG. 3(B). The notations and symbols in FIG. 3(B) are as follows: , 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 triplet excited state of guest material 433 (phosphorescent material) ·S PE : The lowest singlet excited state of an exciplex T PE : The lowest triplet excited state of an exciplex

[0164] Singlet excited state of an 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 (Route E in Figure 3(B) 7 reference).

[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 of the PG ) to obtain light emission (Figure 3(B )'s root E 8 reference).

[0166] In addition, Route E shown above 7 and Route E 8 The process is referred to as ExTET in this specification. (Exciplex-Triplet Energy Transfer) There is a match.

[0167] In addition, organic compound 431 and organic compound 432 receive holes and electrons, respectively. 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 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 emission from the light-emitting layer 443 has a peak on the shorter wavelength side than the emission from the light-emitting layer 444. It is preferable that the light-emitting element has a phosphorescent material that emits light of a short wavelength. Therefore, by using fluorescent light for short wavelengths, It is possible to provide a light emitting element with little deterioration in luminance.

[0170] In addition, the light-emitting layer 443 and the light-emitting layer 444 are configured to emit light of different wavelengths. Thus, a multicolor light-emitting element can be manufactured. The spectrum is a composite 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 lights of these two colors 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 with three primary colors or four or more luminescent colors. White light emission can also be obtained. In this case, either one of the light-emitting layer 443 and the light-emitting layer 444 Alternatively, both of them may be divided into layers, and each divided layer may contain a different light-emitting material. You can do that too.

[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> Examples of the material that can be used for the light-emitting layer 443 include the light-emitting layer 12 shown in the above embodiment 1. It is sufficient to use materials that can be used in 0.

[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. The phosphorescent material 433 (phosphorescent material) is dispersed in the organic compound 431 (host material).

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

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

[0178] The organic compound 432 (assist material) is capable of forming an exciplex with the organic compound 431. In this case, the emission peak of the exciplex is the triplet MLCT (M Ettal to Ligand Charge Transfer (LCT) transition absorption band, Specifically, organic compounds 431 and 43 2 and 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 improved dramatically. When a delayed fluorescent material is used, the absorption band on the longest wavelength side is a 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 emission. As a material capable of converting the triplet excitation energy into light emission, a phosphorescent material is In addition to the above, thermally activated delayed fluorescent materials are also included. In addition, the term "thermally activated delayed fluorescent material" may be used interchangeably with "thermally activated delayed fluorescent material." upconverts the triplet excited state to the singlet excited state by a small amount of thermal energy. This material is capable of reverse intersystem crossing and efficiently emits 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 to 0.1 eV or less.

[0180] In addition, the light emission 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 emission colors of the two 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 with a wavelength of 100 nm or less. The emission peak wavelength of the optical material is preferably shorter than that of the optical material contained in the light-emitting layer 444. It is.

[0181] The light-emitting layers 443 and 444 can be formed by deposition (including vacuum deposition), ink-jet deposition, etc. The insulating layer can be formed by a deposition 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. There can be.

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

[0184] <Example of the configuration 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 structure similar to that of 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. 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 unit 446 and the light-emitting unit 447 are laminated, and a charge generating layer is formed between the light-emitting unit 446 and the light-emitting unit 447. A green layer 445 is provided. 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 a light-emitting layer having a different structure, and the light-emitting unit 447 may preferably use the EL layer 100 shown in FIG.

[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 hole injection layer 411, a hole transport layer 412, an electron The light-emitting unit 447 includes a light-emitting 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. 4(A), a light-emitting element having two light-emitting units has been described. However, the same configuration can be applied to a light-emitting element having three or more stacked light-emitting units. 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, it is possible to emit high-intensity light while keeping the current density low. Furthermore, it is possible to realize a display device with a longer life and a lower power consumption. do.

[0189] At least one of the multiple units includes 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 the present 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 gel contained in the light-emitting layer 449 are The resist material 473 is a compound including the organic compound 131, the organic compound 132, and the gate electrode 474 of 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 described below.

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

[0193] In the light-emitting layer 448, an excited state is formed by carrier recombination. 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 singlet and triplet excited states 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 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 electron energy level (triplet energy transfer). 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 excited energy level of the host material 461 is difficult to use as a luminescent material. When the energy level of the injected ions is higher than the triplet excited energy level of the guest material 462, It is difficult to utilize more than about 25% of the carriers for light emission.

[0196] Next, the energy level of the host material 461 and the guest material 462 in the light-emitting layer 448 is 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 triplet excited state of guest material 462 (fluorescent material)

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

[0198] As shown in Figure 4(B), triplet-triplet annihilation (TTA) iplet Annihilation) (Route E in Figure 4(B) 9 (see), 3 When doublet excitons collide with each other, part of their excitation energy is transferred to the host material. The lowest singlet excited state of 1 (S FH ) in 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) Root E 10 4), and 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. Since it is lower than the energy level, T FG The energy of T FH ToEnergy Gee movement (Route E in Fig. 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] In addition, the light-emitting layer 448 and the light-emitting layer 449 are configured to emit light of different wavelengths. Thus, a multicolor light-emitting element can be manufactured. The spectrum is a composite 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 lights of these two colors complementary to each other, white light can be emitted.

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

[0204] <Light Emitting Mechanism of the Light Emitting Layer 449> The light emitting mechanism of the light emitting layer 449 is similar to that 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 of the singlet excitation is higher than that 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 excitation energy level is lower than the first excitation 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) and the like. Alternatively, 5,12-diphenyltetracene, 5,12-bis(biphenyl-2-yl) Examples include tetracene.

[0208] Guest materials 462 (fluorescent materials) include pyrene derivatives, anthracene derivatives, and trifluoromethane derivatives. Phenylene derivatives, fluorene derivatives, carbazole derivatives, dibenzothiophene derivatives, Dibenzofuran derivatives, dibenzoquinoxaline derivatives, quinoxaline derivatives, pyridine derivatives Examples of the conductor include 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 the above embodiment 1. It is sufficient to use materials that can be used in 0.

[0210] In addition, the emission color of the light-emitting material contained in the light-emitting layer 448 and the emission color of the light-emitting material contained in the light-emitting layer 449 are different. 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 emission colors of the two 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 with a wavelength of 100 nm or less. The emission peak wavelength of the optical material is preferably shorter than that of the optical material contained in the light-emitting layer 449. It is.

[0211] The light-emitting layers 448 and 449 can be formed by deposition (including vacuum deposition), ink-jet deposition, etc. The insulating layer can be formed by a deposition 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.

[0213] (Embodiment 4) 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. The explanation will be given using (B).

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

[0215] <Explanation about the display device> The display device shown in FIG. 5A has a region having pixels of a display element (hereinafter, referred to as a pixel portion 802). A circuit section (hereinafter referred to as a pixel section) is disposed outside the pixel section 802 and has a circuit for driving the pixel. A circuit having a function of protecting the element (hereinafter, a protection circuit 806) The protection circuit 806 is not provided in the configuration. 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 the whole of the pixel portion 802 is not formed on the same substrate, the driving circuit A part or the whole of the path portion 804 is made of COG (Chip On Glass) or TAB (T This can be implemented using the ape 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). A circuit for driving a plurality of display elements (hereinafter referred to as pixel circuit 801) is provided. The path portion 804 is a circuit that outputs a signal (scanning signal) for selecting a pixel (hereinafter, a scanning line driving circuit 804a) to supply signals (data signals) for driving the display elements of the pixels. The image display device 804 includes driver circuits such as a circuit (hereinafter, a signal line driver circuit 804b).

[0218] The scanning line driver circuit 804a includes a shift register and the like. A signal for driving the shift register is input via a terminal portion 807, and a signal is output. For example, a start pulse signal, a clock signal, etc. are input to the scanning line driver circuit 804a. The scanning line driver circuit 804a is a wiring to which a scanning signal is applied (hereinafter, The scanning lines GL_1 to GL_X are connected to the ground. A plurality of driving circuits 804a are provided, and the scanning lines GL_1 to Alternatively, the scanning line driving circuit 804a may control the GL_X by dividing it. However, the present invention is not limited to this, and the scanning line driving circuit 80 4a may also provide another signal.

[0219] The signal line driver circuit 804b includes a shift register and the like. Through the terminal portion 807, a signal for driving the shift register and a source of a data signal are input. The signal line driver circuit 804b drives the pixel circuit based on the image signal. The signal line driver circuit 804b has a function of generating a data signal to be written to the signal line driver circuit 801. A data signal is generated according to a pulse signal obtained by inputting a start pulse, a clock signal, etc. The signal line driver circuit 804b has a function of controlling the output of a data signal. The data lines DL_1 to DL_Y are connected to the data line 101 through the data line 102. Alternatively, the signal line driver circuit 804b may have a function of supplying an initialization signal. However, the present invention is not limited to this, and the signal line driver circuit 804b may also supply other signals. It is possible.

[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-division-multiplexed and output as a data signal. Also, a shift register, etc. The signal line driver circuit 804b may be formed using the same.

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

[0222] The protective circuit 806 shown in FIG. 5A is, for example, 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 data line DL is connected 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 a wiring between the signal line driver circuit 804b and the terminal portion 807. The terminal portion 807 can be connected to the display device from an external circuit. This refers to the part provided with terminals for inputting control signals and image signals.

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

[0224] As shown in FIG. 5A, a pixel section 802 and a driver circuit section 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, 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. It is also possible.

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

[0226] <Pixel circuit configuration example> The pixel circuits 801 shown in FIG. 5A may have a configuration shown in FIG. 5B. 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] A data signal is applied to one of the source and drain electrodes of the transistor 852. 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. are electrically connected.

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

[0230] One of a pair of electrodes of the capacitor 862 is connected to a wiring to which a potential is applied (hereinafter, a potential supply line VL _a), and the other is electrically connected to the source electrode and drain electrode of the transistor 852. The second electrode is electrically connected to the other of the first and second electrodes.

[0231] The capacitor 862 functions as a storage capacitor for storing 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. In addition, the gate electrode of the transistor 854 is electrically connected to the It is electrically connected to the other of the source electrode and the drain electrode.

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

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

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

[0238] In addition, the light-emitting element of one embodiment of the present invention may be an active master having an active element in a pixel of a display device. A display device that uses a trix method or a passive matrix method that does not have active elements in the pixels of the display device. It can be applied to each method.

[0239] In the active matrix method, a transistor is used as an active element (active element, nonlinear element). By using not only transistors but also various active elements (active elements, nonlinear elements), For example, MIM (Metal Insulator Metal) or T It is also possible to use FD (Thin Film Diode) and other elements. Since the number of manufacturing steps is small, it is possible to reduce manufacturing costs and improve yields. Alternatively, these elements can improve the aperture ratio due to their small size. This makes it possible to achieve low power consumption and high brightness.

[0240] As a non-active matrix type, active elements (active elements, nonlinear elements It is also possible to use a passive matrix type that does not use active elements. Since it does not use any nonlinear elements, there are fewer manufacturing steps, which reduces manufacturing costs and improves yield. It is possible to improve the accuracy. Or, it is possible to use active elements (active elements, nonlinear elements) Since the aperture ratio is not increased, it is possible to achieve low power consumption and high brightness. It is possible to do this.

[0241] The configuration shown in this embodiment mode may be appropriately combined with the configurations 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 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 electronic device that combines a display device and an input device is used as an example of the electronic device. A touch panel 2000 having the touch sensor 2000 will be described. The case where the .

[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). The touch panel 2000 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 includes a plurality of pixels on a substrate 2510 and a display device that can supply signals to the pixels. The plurality of wirings 2511 are arranged around the periphery of the substrate 2510. The wire is routed through a wire loop, part of which constitutes the terminal 2519. The terminal 2519 is an FPC 2509 (1) and electrically connect it.

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

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

[0249] The projected capacitive type is classified into self-capacitance type, mutual capacitance type, etc., mainly based on the difference in the driving method. The mutual capacitance method is preferable because it enables simultaneous multi-point detection.

[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 target 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 a plurality of wirings 2598, and the electrode 2592 is It is electrically connected to any other of the multiple wirings 2598.

[0253] As shown in FIGS. 6(A) and 6(B), the electrodes 2592 are a plurality of electrodes repeatedly arranged in one direction. It has a shape in which quadrilaterals are connected at the 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 of ​​the region where no electrodes are provided, reducing variations in transmittance. As a result, the variation in the brightness of the light passing through the touch sensor 2595 can be reduced. can be done.

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

[0257] <Explanation about the display device> Next, the display device 2501 will be described in detail with reference to FIG. 7(A). , which corresponds to a cross-sectional view taken along dashed line X1-X2 in FIG. 6(B).

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

[0259] In the following description, a light emitting element that emits white light is used as a display element. However, the display element is not limited to this. For example, Light emitting elements with different luminous colors may be applied so that the colors are different.

[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 or equal to 1×10 -6 g m -2 ·day -1Possible A flexible material can be preferably used. It is preferable to use a material having a coefficient of thermal expansion approximately equal to that of the plate 2570. For example, is 1×10 -3 / K or less, preferably 5×10 -5 / K or less, preferably 1×10 - 5 A material having a viscosity of 0.1 to 1.0 μm may be preferably used.

[0261] The substrate 2510 is made up of an insulating layer 2510a for preventing impurities from diffusing into the light-emitting element, and a flexible The substrate 2510b and the adhesive layer 2 that bonds the insulating layer 2510a and the flexible substrate 2510b together 510c. The substrate 2570 is a laminate having a structure for preventing diffusion of impurities into the light-emitting element. and a flexible substrate 2570b. 2570b and an adhesive layer 2570c that bonds the first and second layers 2570a and 2570b to each other.

[0262] The adhesive layer 2510c and the adhesive layer 2570c may be made of, for example, polyester or polyolefin. Polyimide, polycarbonate or acrylic The resin may be a polyurethane, epoxy, or silicone. 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 sealing layer has a refractive index larger than that of air. When light is extracted to 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 include a light emitting element 2550R. An inert gas (such as nitrogen or argon) may be filled. In addition, a desiccant may be added to the inert gas. It is also possible to provide a structure in which a material such as an ultraviolet-curing resin or a thermosetting resin is used to absorb moisture. It may be filled with a resin, for example, a PVC (polyvinyl chloride) resin or an 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 above-mentioned sealing material, for example, epoxy resin or glass frit is preferably used. It is preferable to use a material for the sealing material that is impermeable to moisture and oxygen. This is preferable.

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

[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. As the light-emitting element 2550R, for example, any of the light-emitting elements described in Embodiments 1 to 3 can be used. Photonic elements can be applied.

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

[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 emission direction. The light blocking layer 2567BM is provided so as to surround the colored layer 2567R.

[0272] The colored layer 2567R may have a function of transmitting light in a specific wavelength band. For example, a color filter that transmits light in the red wavelength band and 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. By using the above, printing method, inkjet method, etching method using photolithography technology, etc. It can be formed by, for example.

[0273] The display device 2501 is provided with an insulating layer 2521. The insulating layer 2521 is provided to flatten the unevenness caused by the pixel circuit. In addition, the insulating layer 2521 has a function of suppressing diffusion of impurities. This prevents the reliability of the transistors 2502t and the like from being reduced due to the diffusion of impurities. It can be suppressed.

[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 an edge of the lower electrode. A spacer for controlling the distance between the substrate 2510 and the substrate 2570 is provided on the partition wall 2528. It may be formed.

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

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

[0277] In addition, transistors with various structures can be used in 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. may be applied to the display device 2501.

[0278] In addition, there is no particular restriction on the polarity of the transistor 2502t and the transistor 2503t. There is no definition, but a structure with N-type and P-type transistors, an N-type transistor or a P-type 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 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 an electric field strength 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 (Zr), Zr, Lanthanum (La), Cerium (Ce), Tin (Sn), Hafnium (Hf) , or neodymium (Nd).

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

[0280] The touch sensor 2595 includes electrodes 2591 and electrodes 2592 arranged in a staggered pattern on a substrate 2590. 2592, an insulating layer 2593 covering the electrodes 2591 and 2592, and adjacent electrodes 25 91 and a wiring 2594 that electrically connects them.

[0281] The electrode 2591 and the electrode 2592 are formed using a light-transmitting conductive material. Examples of conductive materials having the above structure include indium oxide, indium tin oxide, and indium zinc oxide. Conductive oxides such as zinc oxide, zinc oxide doped with gallium can be used. A film containing graphene may also be used. The film containing graphene may be, for example, a film-like The graphene oxide-containing film formed on the substrate can be reduced to form the graphene oxide-containing film. An example of such a method is the application of heat.

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

[0283] The material used for the insulating layer 2593 is, for example, a resin such as acrylic or epoxy. In addition to resins with siloxane bonds, silicon oxide, silicon oxynitride, aluminum oxide, Alternatively, inorganic insulating materials such as rubber may be used.

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

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

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

[0287] In addition, the multiple 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 is provided to cover the insulating layer 2593 and the wiring 2594, 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 dashed line X5-X6 in FIG. 6(A).

[0293] The touch panel 2000 shown in FIG. 8A is a display device 2501 described in FIG. , and the touch sensor 2595 described in FIG. 7(C) are attached to each other.

[0294] The touch panel 2000 shown in FIG. 8A is similar to the touch panel 2000 described in FIG. 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. In addition, it is preferable that the adhesive layer 2597 is transparent. The material 597 may be a thermosetting resin or an ultraviolet-curing resin. For example, Acrylic resin, urethane resin, epoxy resin, or siloxane resin can be used. This can be done.

[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, a touch panel having a different configuration from that shown in FIG. 8(A) will be examined using FIG. 8(B). He explains.

[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 location of the switch sensor 2595 is different. The different configurations are described in detail here, and a similar configuration The description of the touch panel 2000 is cited for the parts in which 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 the 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 FIG. 8(A) and (B), the light emitted from the light emitting element is incident on the upper and lower surfaces of the substrate. It may be injected into either one or both.

[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. 9 ) 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 of which has six wires. 9(A) shows a capacitance 2603 formed by overlapping an electrode 2621 and an electrode 2622. The electrodes 2621 and 2622 may have interchangeable functions. stomach.

[0305] The pulse voltage output circuit 2601 is a circuit for applying pulses to the wirings X1-X6 in sequence. When a pulse voltage is applied to the wiring of X1-X6, the voltage that forms the capacitance 2603 An electric field is generated between the electrodes 2621 and 2622. The electric field generated between the electrodes is blocked by By using the change in the mutual capacitance of the capacitance 2603, the proximity of the object to be detected or A contact can be detected.

[0306] The current detection circuit 2602 detects the change in mutual capacitance of the capacitor 2603 between the wirings Y1-Y6. This is a circuit to detect changes in current at the sensor. The wiring of Y1-Y6 detects the proximity of the object to be detected, Or, if there is no contact, the detected current value will not change, but the proximity of the object to be detected, or When the mutual capacitance decreases due to contact, a change in the current value is detected. The detection may be performed using an integrating circuit or the like.

[0307] Next, FIG. 9B shows input and output of the mutual capacitance type touch sensor shown in FIG. The timing chart of the waveform is shown in FIG. 9B. In addition, in FIG. 9(B), when no object is detected (non-touched), The two cases shown are Y1- For the wiring 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 sequence, and the The waveform in the Y6 wiring changes. When there is no proximity or contact of the object to be detected, X1-X6 The waveforms of Y1-Y6 change uniformly according to the change in the voltage of the wiring. Or, at the point of contact, the current value decreases, and the corresponding voltage waveform also changes. do.

[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 description> In FIG. 9A, only a capacitor 2603 is provided at the intersection of the wiring as a touch sensor. The configuration of a passive matrix touch sensor has been shown, but The touch sensor may be an active matrix type. An example of a 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 voltage is applied to either the source or drain of the transistor 2613. A voltage VRES is applied to one electrode of a capacitor 2603 and a transistor 2611. The transistor 2611 has a source and a drain that are electrically connected to each other. One of the source and drain of the transistor 2612 is electrically connected to the other of the source and drain of the transistor 2612. A signal G1 is applied to the gate of the transistor 2612, and a signal S is applied to the source or The other electrode of the drain is electrically connected to the wiring ML. The other electrode of the capacitor 2603 is connected to a voltage VS S is given.

[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 input is connected. When a potential that turns off the transistor 2613 is applied, the potential of the node n is Retained.

[0314] Next, the mutual capacitance of the capacitor 2603 changes due to the proximity or contact of a detection object such as a finger. Accordingly, the potential of the node n changes from VRES.

[0315] The read operation applies a potential to the signal G1 that turns on the transistor 2612. A current flows through the transistor 2611 in accordance with the potential of the node n, that is, a current flows through the wiring ML. By detecting this current, the proximity or contact of the object to be detected can be detected. This can be done.

[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 can be It is possible to hold the voltage for a long period of time, and the operation of re-supplying VRES to node n (restart) is performed. This can reduce the frequency of refresh operations.

[0317] The configuration shown in this embodiment mode may be appropriately combined with the configurations 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 described with reference to FIG. 11 and FIG.

[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 the FPC8003 and the touch sensor 8005 connected to the FPC8006 are A display device 8006, a frame 8009, a printed circuit board 8010, and a battery 8011 are provided. do.

[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 a touch sensor 8004 and a 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 that is connected to 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 plate 8009 may 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 when using a commercial power source.

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

[0326] <Electronic device information> 12(A) to 12(G) are diagrams showing electronic devices. These electronic devices are A body 9000, a display unit 9001, a speaker 9003, and operation keys 9005 (power switch, etc.) includes an operation switch), a connection terminal 9006, a sensor 9007 (force, displacement, position, speed, Acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substances, sound, time, hardness, electricity Measures field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared rays The device may have a built-in microphone 9008, etc.

[0327] The electronic devices illustrated in FIGS. 12A to 12G can have various functions. For example, the function to display various information (still images, videos, text images, etc.) on the display, Sensor function, calendar, date or time display function, various software ( A function to control processing by a program, wireless communication function, and various functions using wireless communication function Functions for connecting to computer networks, transmitting various data using wireless communication functions, or receiving the program or data recorded on the recording medium, and displaying the program or data. The display unit may have a function of displaying the information on the display unit. The functions that the electronic device shown in the figure can have are not limited to these, and the electronic device may have a variety of functions. Although not shown in FIG. 12(A) to FIG. 12(G), the electronic device may include The electronic device may have a plurality of display units. The function to take pictures, record videos, and store the images on a recording medium (external or built-in to the camera) ) and a function for displaying the captured image on a display unit.

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

[0330] FIG. 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, the mobile information terminal 9101 can be used as a smartphone. Although the speaker 9003, the connection terminal 9006, the sensor 9007, etc. are omitted in the figure, The mobile information terminal 9100 shown in FIG. 12(A) can be installed in the same position. The information terminal 9101 can display text and image information on multiple surfaces. For example, Three operation buttons 9050 (also called operation icons or simply icons) are displayed on the display unit 900. The information 9051 shown in the dashed rectangle can be displayed on one side of the display unit 90. 01. An example of the information 9051 is an e-mail Displays to notify you of incoming calls, SNS (social networking services), etc. , subject of email or SNS, sender name of email or SNS, date and time, time, Battery level, antenna reception strength, etc. Or, information 9051 is displayed. Instead of the information 9051, an operation button 9050 or the like may be displayed at that position.

[0331] FIG. 12C is a perspective view showing a portable information terminal 9102. , and has a function of displaying information on three or more faces of the display unit 9001. An example is shown in which information 9053 and information 9054 are displayed on different sides. The user of the portable information terminal 9102 holds the portable information terminal 9102 in the breast pocket of the clothes. In this state, the display (information 9053 in this case) can be confirmed. The telephone number or name of the caller is displayed on the mobile information terminal 9102 so that it can be observed from above. The user can read the display without taking the mobile information terminal 9102 out of his pocket. You can check the number and decide whether to answer the call or not.

[0332] 12(D) is a perspective view showing a wristwatch-type portable information terminal 9200. The 9200 is used for mobile phone calls, e-mail, document browsing and writing, music playback, and Internet communications. It is possible to execute various applications such as computer games. The display unit 9001 has a curved display surface, and displays information along the curved display surface. In addition, the portable information terminal 9200 can perform short-distance wireless communication according to a communication standard. For example, by communicating with a wireless headset, The mobile information terminal 9200 also has a connection terminal 9006. It has a connector and can directly exchange data with other information terminals. Charging can also be performed via the connection terminal 9006. Power may also be supplied wirelessly without going through 6.

[0333] 12(E), (F), and (G) are perspective views showing a foldable portable information terminal 9201. FIG. 12E is a perspective view of the portable information terminal 9201 in an unfolded state. (F) shows the mobile information terminal 9201 being changed from one of the unfolded and folded states to the other. FIG. 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 unfolded. When the display is turned on, the seamless, wide display area provides excellent visibility of the display. The display unit 9001 of the display device 9001 is made up of three housings 9000 connected by hinges 9055. The two housings 9000 are supported by the hinge 9055. The portable information terminal 9201 can be reversibly transformed from an unfolded state to a folded state. For example, the portable information terminal 9201 can be bent with a radius of curvature of 1 mm or more and 150 mm or less. It can be done.

[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 the present embodiment. In the case of a display device, the display device may be flexible and capable of displaying information along a curved display surface, or may be foldable. Although the configuration of the display unit is exemplified as being foldable, the present invention is not limited thereto, and may be applied to a display unit that is not flexible and has a flat surface. The display may be provided on the display unit.

[0335] The configuration shown in this embodiment mode may be appropriately combined with the configurations 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 such a curved light-emitting area, a lighting device 8502 can be formed. The light-emitting element shown in this embodiment mode has a thin film shape, and the design of the housing has a high degree of freedom. Therefore, it is possible to form 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 makes it possible to provide a lighting device that also functions as furniture.

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

[0340] The structure described in this embodiment may be used in appropriate combination with structures described in other embodiments. There can be. EXAMPLES

[0341] In this example, a thermally activated delayed fluorescent substance (first organic compound) and a host material (second organic compound) were The light-emitting element 1 and the light-emitting element 2 are made by mixing the compound and a fluorescent guest material in the light-emitting layer. An example of the fabrication of the light-emitting element 2) is shown in FIG. 14. 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 above-mentioned embodiment 1.

[0342] [ka]

[0343] [Table 4]

[0344] A method for fabricating the light-emitting element 1 and the light-emitting element 2 will be described below.

[0345] <Fabrication of Light-emitting Device 1> An electrode 501 made of indium tin oxide containing silicon oxide (abbreviation: ITS The electrode 501 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 substrate surface 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 electrodes 501 are formed is placed so that the surface on which the electrodes 501 are formed faces downward. 0 to 1 x 10 -4 The substrate holder was placed in a vacuum deposition apparatus that was depressurized to about Pa. Then, DBT3P-II and oxidized ZnO were deposited on the electrode 501 as a hole injection layer 531. Molybdenum (MoO 3 ) and the weight ratio (DBT3P-II:MoO 3 ) is 1:0.5 The deposition was carried out so that the thickness of the layer became 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 deposition was carried out as follows.

[0349] Next, a light-emitting layer 521 containing PCCzPTzn and 4,6mCz P2Pm and 1,6mMemFLPAPrn are mixed in a weight ratio (PCCzPTzn:4,6m CzP2Pm:1,6mMemFLPAPrn) is 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 phosphor (first organic compound), and 4,6mCzP2Pm is is the host material (the second organic compound) and 1,6mMemFLPAPrn is the guest material. be.

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

[0351] Next, lithium fluoride (abbreviation: Li 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 so as to give 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 performed using a resistance heating method.

[0354] Next, in a glove box with a nitrogen atmosphere, the sealing group is sealed using a sealing material for organic electroluminescence. The plate was fixed onto 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 to the substrate. 6J / cm 2 The light-emitting element 1 was obtained by the above steps. Ta.

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

[0356] That is, the light-emitting layer 521 of the light-emitting element 2 is made 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 (the second organic compound), and TBP is the gate It is a steel material.

[0357] <Measurement of Transient Fluorescence Properties> Here, in the light-emitting elements of this embodiment (light-emitting element 1 and light-emitting element 2), The transient fluorescence characteristics 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 performed using thin film samples prepared by the method described above. Then, a sealing substrate is fixed onto the quartz substrate on which the thin film sample is 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 is applied, the quartz substrate and the sealing substrate are bonded together, and ultraviolet light with a wavelength of 365 nm is 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 emission was then time-resolved and measured 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 for 1 The thin film was irradiated with light at a frequency of 0 Hz, and the data was repeatedly measured and accumulated to obtain the signal-to-noise ratio (S / N). The measurements were performed at room temperature (23°C).

[0360] The measured transient fluorescence characteristics of PCCzPTzn are shown in FIG.

[0361] In addition, the attenuation curve shown in FIG. 15 was fitted using the following formula (4): I did.

[0362]

number

[0363] In formula (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 thin film sample of PCCzPTzn include It was found that the fluorescence component had a light lifetime of 0.015 μs and a delayed fluorescence component had 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 to be the case.

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

[0365] Also, 1000cd / m 2 The element characteristics of the light-emitting element 1 and the light-emitting element 2 in the vicinity are shown in Table 5. As shown in.

[0366] [Table 5]

[0367] Furthermore, light-emitting element 1 and light-emitting element 2 were supplied with 2.5 mA / cm 2 When a current is applied at a current density of The electroluminescence spectra are shown in FIG. 19. As shown in FIG. 19, the light-emitting element 1 and the light-emitting element 2 each have It was found that the blue light emitted was due to the guest material.

[0368] In addition, as shown in FIGS. 16 to 18, the driving voltage of the light-emitting element 1 and the light-emitting element 2 is low. The device exhibited high luminous efficiency. In particular, the device 2 had an external quantum efficiency of more than 10% at maximum. The efficiency is shown in Fig. 1. Using a fluorescent material as the guest material, the energy from the singlet excited state alone is 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 about 6% at maximum. The light-emitting elements 1 and 2, which were made of the same material, showed higher external quantum efficiency. This is because of the thermal activation delay. The triplet excited state generated by the recombination of 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 phosphor has an energy level equal to or higher than the HOMO of the host material. The LUMO of the thermally activated delayed phosphor has an energy level lower than the LUMO of the host material. In addition, as shown in Table 2 in the first embodiment, the oxidation potential of the thermally activated delayed phosphor 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 greater than or equal to the HOMO estimated from the oxidation and reduction potentials, The energy level of the LUMO is 1.0, the HOMO of the thermally activated delayed phosphor is 1.0, and the HO of the host material is 1.0. The LUMO of the thermally activated delayed phosphor has an energy level higher than the LUMO of the host material. It has an energy level lower than MO.

[0370] In addition, the triplet excitation energy level of 1,6mMemFLPAPrn is 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 element 1 and the light-emitting element 2, the thermally activated delayed phosphor can be efficiently used. The carriers recombine, and the energies of both the singlet and triplet excited states are Therefore, the energy can be efficiently transferred to the guest material. The optical element 2 has been shown to have high luminous efficiency.

[0372] In addition, since the light-emitting elements 1 and 2 showed high luminous efficiency, it was confirmed that the host material and the thermally active 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. The weight ratio of the host material to the guest material (host material:guest material) is preferably 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. EXAMPLES

[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 thermally activated delayed phosphor. Examples of light-emitting devices in which the weight ratio of the cations was changed (light-emitting devices 3 to 5, The cross-sectional views of the light-emitting elements fabricated in this example are shown. The schematic diagram is the same as that shown in FIG. 14 in the previous 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 to a thickness of 110 nm by sputtering 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 substrate surface 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 electrodes 501 are formed is placed so that the surface on which the electrodes 501 are formed faces downward. 0 to 1 x 10 -4 The substrate was fixed to a substrate holder installed in a vacuum deposition apparatus with the pressure reduced to about Pa. Thereafter, a hole injection layer 531 was formed on the electrode 501 using DBT3P-II and MoO 3 and the weight ratio (DBT3P-II:MoO 3 ) 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 formed on the hole injection layer 531 to a thickness of 20 nm. The deposition was carried out as follows.

[0383] Next, a light-emitting layer 521 was formed on the hole transport layer 532 by depositing a mixture of 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 thermally activated. The first organic compound is a delayed fluorescent material, and the second organic compound is Cz2DBT. (substance), and 1,6mMemFLPAPrn is the guest material.

[0384] Next, on the light-emitting layer 521, as the electron transport layer 533, Bphen was deposited to 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 deposition was carried out as follows.

[0386] Next, an electrode 502 made of Al was formed on the electron injection layer 534 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 performed using a resistance heating method.

[0388] Next, in a glove box with a nitrogen atmosphere, the sealing group is sealed using a sealing material for organic electroluminescence. The plate was fixed onto 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 to the substrate. 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 element 4 and the light-emitting element 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. did.

[0390] In the light-emitting element 4, the light-emitting layer 521 is made of PCCzPTzn, Cz2DBT, and TBP. The weight ratio (PCCzPTzn:Cz2DBT:TBP) is 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 TBP is the guest material. The light-emitting element 4 is a light-emitting element having a similar structure to 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 PCCzPTzn, CzTAZ1, and TBP The weight ratio (PCCzPTzn:CzTAZ1:TBP) is 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 CzTAZ1 is The second organic compound is the host material, and TBP is the guest material. The light-emitting element 5 is a light-emitting element having a similar structure to 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 material containing Cz2DBT and 1,6mMemFLPA Prn and Cz2DBT:1,6mMemFLPAPrn weight ratio is 1:0.05 The luminescent layer 521 was co-deposited to a thickness of 30 nm. z2DBT is the host material (second organic compound) and 1,6mMemFLPAPrn is That is, the comparative light-emitting element 1 is a thermally activated delayed phosphor (first organic compound). It is a light-emitting element that does not use any organic EL element.

[0393] In the comparative light-emitting element 2, the light-emitting layer 521 is made of PCCzPTzn, Cz2DBT, and ,6mMemFLPAPrn and the weight ratio (PCCzPTzn:Cz2DBT:1,6m MemFLPAPrn) is 0.1:0.9:0.05 and the thickness is 30 nm. In the light-emitting layer 521, PCCzPTzn exhibits thermal activation delayed fluorescence. The photoconductor (first organic compound) and Cz2DBT is 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 PCCzPTzn, CzDBT, 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 phosphor (first organic compound), and CzDBT is the host material (the 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 PCCzPTzn, CzTAZ1, and T The weight ratio of BP and PCCzPTzn:CzTAZ1: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 phosphor (first organic compound), and CzTAZ1 is the host material (the second organic compound) and TBP is the guest material. The light-emitting element 4 has a similar structure to the light-emitting element 5, except for the concentration of the guest material. It is a light-emitting element.

[0396] <Characteristics of light-emitting element> Next, the current efficiency-luminance of the light-emitting element 3, the comparative light-emitting element 1, and the comparative light-emitting element 2 fabricated as above was measured. The intensity characteristics are shown in Fig. 20, the current-voltage characteristics in Fig. 21, the external quantum efficiency-luminance characteristics in Fig. 22, and The light-emitting element 3, the comparative light-emitting element 1, and the comparative light-emitting element 2 were each charged at 2.5 mA / c. m 2 The electroluminescence spectrum when a current was applied at a current density of 1000 nm is shown in FIG. 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. , and 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 applied at a current density of 1000 nm is shown in FIG. The measurements were carried out at room temperature (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 element 1 to the comparative light-emitting element 4 emits blue light derived from the guest material. It can be seen that...

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

[0401] The thermally activated delayed phosphor (PCCzPTzn) and host material (CzDB The results of the measurement of the oxidation and reduction potentials of T and 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 potential of the thermally activated delayed phosphor was 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 greater than or equal to the HOMO estimated from the oxidation and reduction potentials, 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 phosphor has an energy level equal to or higher than the HOMO of the host material. Therefore, it is a thermally activated delayed fluorescent material with high efficiency. 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] In addition, 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 improves the luminescence efficiency. This is 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] In addition, the light-emitting element 3 has a higher luminous efficiency than the comparative light-emitting element 2. The weight of the host material (Cz2DBT) and the 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 the triplet excited state of the guest material can be suppressed.

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

[0407] Therefore, the weight ratio of the host material to the thermally activated delayed phosphor (host material: thermally activated delayed phosphor) 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 having 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 Light-emitting layer 131 Organic compounds 132 Organic compounds 133 Guest Materials 150 Light emitting element 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 Light Emitting Unit 442 Light Emitting Unit 443 Emitting layer 444 Emitting layer 445 Charge generation layer 446 Light Emitting Unit 447 Light Emitting Unit 448 Emitting layer 449 Emitting layer 450 Light emitting element 452 Light emitting element 461 Host Materials 462 Guest Materials 471 Organic compounds 472 Organic compounds 473 Guest Materials 501 Electrode 502 Electrode 520 Substrate 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 driver circuit 804b Signal line driver circuit 806 protection circuit 807 Terminal section 852 Transistor 854 Transistor 862 Capacitor 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 Insulating layer 2528 Bulkhead 2550R Light emitting element 2560 Sealing layer 2567BM light shielding layer 2567p anti-reflection layer 2567R colored layer 2570 PCB 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 Portable information terminal 9102 Portable information terminal 9200 Mobile Information Terminal 9201 Portable information terminals

Claims

1. A light-emitting layer is provided between a pair of electrodes, The light-emitting layer includes a first organic compound having a function of exhibiting thermally activated delayed fluorescence at room temperature, a second organic compound having a π-electron-rich heteroaromatic skeleton or an aromatic amine skeleton, and a guest material having a function of exhibiting fluorescence (excluding a combination in which the first organic compound is 2,4,6-Tri(4-(10H-phenoxazine-10H-yl)phenyl)-1,3,5-triazine (tri-PXZ-TRZ), the second organic compound is 4,4'-bis(9-carbazolyl)-1,1'-biphenyl (CBP), and the guest material is tetraphenyldibenzoperiflancthene (DBP)). 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 a LUMO level of the first organic compound has an energy level equal to or lower than a LUMO level of the second organic compound.

2. A light-emitting layer is provided between a pair of electrodes, The light-emitting layer includes a first organic compound having a function of exhibiting thermally activated delayed fluorescence at room temperature, a second organic compound having a π-electron-rich heteroaromatic skeleton or an aromatic amine skeleton, and a guest material having a function of exhibiting fluorescence (excluding a combination in which the first organic compound is 2,4,6-Tri(4-(10H-phenoxazine-10H-yl)phenyl)-1,3,5-triazine (tri-PXZ-TRZ), the second organic compound is 4,4'-bis(9-carbazolyl)-1,1'-biphenyl (CBP), and the guest material is tetraphenyldibenzoperiflancthene (DBP)). 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 a reduction potential of the first organic compound is equal to or higher than a reduction potential of the second organic compound.

3. In claim 1 or 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 first π-electron rich heteroaromatic skeleton has one or more selected from the group consisting of 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 a color filter, a sealing material, or a transistor.

7. A display device according to claim 6; An electronic device having a housing or a touch sensor.

8. A light emitting device according to any one of claims 1 to 5, A lighting device having a housing or a touch sensor.

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