Light-emitting element

Abstract

In a light-emitting device having a fluorescent material as the light-emitting substance, a light-emitting device with high luminescence efficiency is available. To provide an optical element. [Solution] The device has a pair of electrodes and an EL layer provided between the pair of electrodes, and the EL layer emits light. The device has layers, and the light-emitting layer comprises a host material and a guest material, and the host material is singlet excited The difference between the energy level and the triplet excitation energy level is greater than 0 eV and less than or equal to 0.2 eV. The guest material has the ability to emit fluorescence, and the triplet excitation energy of the host material The energy level is higher than the triplet excitation energy level of the guest material.

Description

[Technical Field]

[0001] One aspect of the present invention involves sandwiching a light-emitting layer, which emits light when an electric field is applied, between a pair of electrodes. A light-emitting element, or a display device, electronic device, and lighting device having said light-emitting element. ru.

[0002] Furthermore, one aspect of the present invention is not limited to the above-mentioned technical field. One aspect of the technical field relates to a product, method, or method of manufacture. One aspect of the invention is a process, machine, manufacture, or composition. This relates to (of matter). Therefore, the disclosures disclosed in this specification more specifically are as follows: One aspect of the technology described is semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, and lighting. Examples include devices, energy storage devices, memory devices, methods for driving them, or methods for manufacturing them. It can be listed as follows. [Background technology]

[0003] In recent years, electroluminescence (EL) Research and development of light-emitting devices using this technology are actively underway. The basic configuration of these light-emitting devices is The device consists of a layer containing a light-emitting material (EL layer) sandwiched between a pair of electrodes. By applying a voltage between them, light emission can be obtained from a light-emitting material.

[0004] Since the aforementioned light-emitting element is self-illuminating, the display device using it offers excellent visibility and battery life. It has advantages such as not requiring crystalline materials and consuming less power. Furthermore, it can be manufactured to be thin and lightweight. It also has advantages such as a high response speed.

[0005] Various studies are being conducted to improve the luminescence efficiency of light-emitting elements. For example, thermal activation delay Thermally activated delayed fluorescence By creating a light-emitting element having a nce:TADF body and a fluorescent material, thermal activity A method has been proposed to transfer the energy of S1 of a fluorescence-delayed phosphor to S1 of a fluorescence-emitting material. (See Patent Document 1). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2014-45179 [Overview of the project] [Problems that the invention aims to solve]

[0007] In a light-emitting device having a fluorescent material as the light-emitting substance, the light-emitting device has a luminescent efficiency In order to increase the singlet excited state, not only is it necessary to generate a singlet excited state from a triplet excited state, but also the singlet It is important to be able to efficiently obtain light emission from the excited state, that is, to have a high fluorescence quantum yield. ru.

[0008] In one aspect of the present invention, a light-emitting element having a fluorescent material as a light-emitting substance, One of the objectives is to provide a light-emitting element with high light efficiency. Alternatively, in one aspect of the present invention, One of the objectives is to provide a novel light-emitting element. Alternatively, in one aspect of the present invention, One of the challenges is to provide a novel light-emitting element with high light efficiency and reduced power consumption. Alternatively, one of the objectives is to provide a novel display device.

[0009] Furthermore, the description of the above problems does not preclude the existence of other problems. The approach does not necessarily need to solve all of these problems. Other problems are addressed in the details. This will become clear from the descriptions in the documents, etc., and it is not possible to extract any issues other than those mentioned above from the descriptions in the specifications, etc. It is possible to release it. [Means for solving the problem]

[0010] One aspect of the present invention comprises a pair of electrodes and an EL layer provided between the pair of electrodes, The layer has an emissive layer, and the emissive layer has a host material and a guest material, and the host material is The difference between the singlet excitation energy level and the triplet excitation energy level is greater than 0 eV, which is 0.2 eV. The V is less than or equal to the host material, and the guest material has the ability to emit fluorescence, and is triple the host material. The triplet excitation energy level is characterized by being higher than the triplet excitation energy level of the guest material. This is a light-emitting element.

[0011] Another aspect of the present invention comprises a pair of electrodes and an EL layer provided between the pair of electrodes. The EL layer has a light-emitting layer, and the light-emitting layer has a host material and a guest material, The first material exhibits thermally activated delayed fluorescence at room temperature, while the second material is capable of emitting fluorescence. It has the ability to emit light from thermally activated delayed fluorescence of the host material, and the emission energy of the phosphorescent emission of the guest material This light-emitting element is characterized by having a higher energy output than energy.

[0012] Another aspect of the present invention comprises a pair of electrodes and an EL layer provided between the pair of electrodes. The EL layer has a light-emitting layer, and the light-emitting layer has a host material and a guest material, The material comprises a first organic compound and a second organic compound, the first organic compound and the second The organic compounds are combinations that form excited complexes, and the singlet excitation energy of the excited complexes - The difference between the level and the triplet excitation energy level is greater than 0 eV and less than or equal to 0.2 eV, and ges The material has the ability to emit fluorescence, and the triplet excitation energy level of the excited complex This is a light-emitting element characterized by having an excitation energy level higher than the triplet excitation energy level of the guest material. .

[0013] Another aspect of the present invention comprises a pair of electrodes and an EL layer provided between the pair of electrodes. The EL layer has a light-emitting layer, and the light-emitting layer has a host material and a guest material, The material comprises a first organic compound and a second organic compound, the first organic compound and the second The organic compounds are combinations that form excited complexes, which are thermally activated at room temperature. The guest material exhibits fluorescence and has the ability to emit fluorescence, and the thermal activity of the excited complex The emission energy of delayed fluorescence is characterized by being higher than the phosphorescence emission energy of the guest material. This is a light-emitting element.

[0014] Another aspect of the present invention comprises a pair of electrodes and an EL layer provided between the pair of electrodes. The EL layer has a light-emitting layer, and the light-emitting layer has a host material and a guest material, The material comprises a first organic compound and a second organic compound, the first organic compound and the second The organic compounds are combinations that form excited complexes, and the singlet excitation energy of the excited complexes - The difference between the level and the triplet excitation energy level is greater than 0 eV and less than or equal to 0.2 eV, and ges The material has the function of emitting fluorescence, and the first organic compound and the second organic compound The triplet excitation energy level of the compound is higher than that of the excited complex. This is a light-emitting element characterized by the following:

[0015] Another aspect of the present invention comprises a pair of electrodes and an EL layer provided between the pair of electrodes. The EL layer has a light-emitting layer, and the light-emitting layer has a host material and a guest material, The material comprises a first organic compound and a second organic compound, the first organic compound and the second The organic compounds are combinations that form excited complexes, and these excited complexes exhibit thermally activated delayed fluorescence. The guest material exhibits the ability to emit fluorescence and is a first organic compound and The phosphorescent emission energy of the second organic compound is the emission energy of the thermally activated delayed fluorescence of the excited complex. This light-emitting element is characterized by being higher than -

[0016] Another aspect of the present invention comprises a pair of electrodes and an EL layer provided between the pair of electrodes. The EL layer has a light-emitting layer, and the light-emitting layer has a host material and a guest material, The material comprises a first organic compound and a second organic compound, the first organic compound and the second The organic compounds are combinations that form excited complexes, and the singlet excitation energy of the excited complexes - The difference between the level and the triplet excitation energy level is greater than 0 eV and less than or equal to 0.2 eV, and ges The material has the ability to emit fluorescence, and the triplet excitation energy level of the excited complex This is higher than the triplet excitation energy level of the guest material, and the first organic compound and the second The triplet excitation energy level of an organic compound is higher than the triplet excitation energy level of an excited complex. This light-emitting element is characterized by its high performance.

[0017] Another aspect of the present invention comprises a pair of electrodes and an EL layer provided between the pair of electrodes. The EL layer has a light-emitting layer, and the light-emitting layer has a host material and a guest material, The material comprises a first organic compound and a second organic compound, the first organic compound and the second The organic compounds are combinations that form excited complexes, and these excited complexes exhibit thermally activated delayed fluorescence. The guest material exhibits the ability to emit fluorescence and has a delayed thermal activation of the excited complex. The fluorescence emission energy is higher than the phosphorescence emission energy of the guest material, and the first organic compound The phosphorescence emission energy of the substance and the second organic compound is the emission of thermally activated delayed fluorescence of the excited complex. This light-emitting element is characterized by having an energy higher than the specified limit.

[0018] Furthermore, in each of the above configurations, the weight ratio of the guest material to the host material is greater than 0. It is preferable that the value is 0.05 or less.

[0019] Furthermore, in each of the above configurations, the triplet excitation energy level of the first organic compound and the second The difference between the triplet excitation energy level of the organic compound and the excitation energy level is preferably less than 0.4 eV.

[0020] Furthermore, in each of the above configurations, either the first organic compound or the second organic compound However, it is preferable that it has a fused heterocyclic skeleton, and that the fused heterocyclic skeleton has a diazine skeleton. In this case, either the first organic compound or the second organic compound has a carbazole skeleton, It has a fused heterocyclic skeleton, and it is preferable that the fused heterocyclic skeleton has a diazine skeleton. Alternatively, Either the first organic compound or the second organic compound has a carbazole skeleton and a contracted structure. It has a heterocyclic skeleton, and the condensed heterocyclic skeleton has a diazine skeleton and is condensed with a carbazole skeleton. Preferably, it has a structure in which a heterocyclic skeleton is bonded via an arylene group, and is carbazole It is preferable that the structure has a bond at position 9 of the skeleton via an arylene group. Alternatively, Either the first organic compound or the second organic compound has a carbazole skeleton and a ben It has a zoflopyrimidine skeleton, and the carbazole skeleton and the benzoflopyrimidine skeleton are It is preferable that the structure has a bond at the 9-position of the rubazole skeleton via an arylene group.

[0021] Furthermore, in each of the above configurations, either the first organic compound or the second organic compound However, it has a carbazole skeleton and an aromatic amine skeleton, and the carbazole skeleton and the aromatic amine A structure in which the carbazole skeleton and the carbazole skeleton are bonded at position 9, or the carbazole skeleton It is preferable that the structure has a bond at the 9th position via an arylene group.

[0022] Furthermore, in each of the above configurations, the EL layer further comprises a hole injection layer, a hole transport layer, an electron transport layer, It is preferable to have one of the electron injection layers selected from among them.

[0023] Another aspect of the present invention includes a light-emitting element of the above configuration and a color filter. It is a display device. Another aspect of the present invention is the display device and a housing or touch sensor. It is an electronic device having a light-emitting element of the above configuration, It is a lighting device having a housing or a touch sensor. [Effects of the Invention]

[0024] In one aspect of the present invention, a light-emitting element having a fluorescent material as a light-emitting substance, It is possible to provide a light-emitting element with high luminescence efficiency. Alternatively, according to one aspect of the present invention, a novel A light-emitting element can be provided. Alternatively, according to one aspect of the present invention, a light-emitting element with high luminous efficiency can be provided. It is possible to provide a novel light-emitting element with reduced power consumption, or a novel display device. We can provide this.

[0025] Furthermore, the description of these effects does not preclude the existence of other effects. One embodiment does not necessarily have to possess all of these effects. Furthermore, other effects may be considered. This will become clear from the description in the specification, drawings, claims, etc., and the specification, drawings It is possible to extract effects other than those mentioned above from the descriptions in the surfaces, claims, etc. [Brief explanation of the drawing]

[0026] [Figure 1] A schematic cross-sectional diagram of a light-emitting element, a schematic cross-sectional diagram of a light-emitting layer, and a schematic diagram illustrating the correlation of energy levels. [Figure 2] A schematic diagram of the cross-section of the light-emitting layer, and a schematic diagram illustrating the correlation of energy levels. [Figure 3] A diagram illustrating the emission spectrum according to the embodiment. [Figure 4] A diagram illustrating the phosphorescent emission spectrum according to the embodiment. [Figure 5] A schematic cross-sectional diagram illustrating the light-emitting element, and a diagram illustrating the correlation of energy levels in the light-emitting layer. [Figure 6] A schematic cross-sectional diagram illustrating the light-emitting element, and a diagram illustrating the correlation of energy levels in the light-emitting layer. [Figure 7] Block diagrams and circuit diagrams illustrating the display device. [Figure 8] A perspective view showing an example of a touch panel. [Figure 9] A cross-sectional view showing an example of a display device and a touch sensor. [Figure 10] A cross-sectional view showing an example of a touch panel. [Figure 11] Block diagram and timing chart of the touch sensor. [Figure 12] Circuit diagram of a touch sensor. [Figure 13] A perspective view illustrating the display module. [Figure 14] A diagram explaining electronic devices. [Figure 15] A diagram illustrating a lighting device. [Figure 16] A cross-sectional view illustrating the structure of the light-emitting element in the embodiment. [Figure 17] A diagram illustrating the brightness-current density characteristics of light-emitting elements 1 to 4 in the embodiment. [Figure 18] A diagram illustrating the brightness-current density characteristics of light-emitting elements 5 to 7 in the embodiment. [Figure 19] A diagram illustrating the brightness-voltage characteristics of light-emitting elements 1 to 4 in the embodiment. [Figure 20] A diagram illustrating the brightness-voltage characteristics of light-emitting elements 5 to 7 in the embodiment. [Figure 21] A diagram illustrating the current efficiency-luminance characteristics of light-emitting elements 1 to 4 in the embodiment. [Figure 22] A diagram illustrating the current efficiency-luminance characteristics of the light-emitting elements 5 to 7 in the embodiment. [Figure 23] A diagram illustrating the current-voltage characteristics of light-emitting elements 1 to 4 in the embodiment. [Figure 24] A diagram illustrating the current-voltage characteristics of the light-emitting elements 5 to 7 in the embodiment. [Figure 25] A diagram illustrating the external quantum efficiency-luminance characteristics of light-emitting elements 1 to 4 in the embodiment. [Figure 26] A diagram illustrating the external quantum efficiency-luminance characteristics of light-emitting elements 5 to 7 in the embodiment. [Figure 27] A diagram illustrating the electroluminescence spectra of light-emitting elements 1 to 4 in the embodiment. [Figure 28] A diagram illustrating the electroluminescence spectra of light-emitting elements 5 to 7 in the embodiment. [Figure 29] A diagram illustrating the transient EL characteristics of light-emitting elements 1, 6, and 7 in the embodiment. [Figure 30] A diagram illustrating the transient EL spectrum of the light-emitting element 6 in the embodiment. [Figure 31]A diagram illustrating the brightness-current density characteristics of light-emitting elements 8 and 9 in the embodiment. [Figure 32] A diagram illustrating the brightness-voltage characteristics of light-emitting elements 8 and 9 in the embodiment. [Figure 33] A diagram illustrating the current efficiency-luminance characteristics of the light-emitting elements 8 and 9 in the embodiment. [Figure 34] A diagram illustrating the current-voltage characteristics of light-emitting elements 8 and 9 in the embodiment. [Figure 35] A diagram illustrating the external quantum efficiency-luminance characteristics of light-emitting elements 8 and 9 in the embodiment. [Figure 36] A diagram illustrating the electroluminescence spectra of light-emitting elements 8 and 9 in the embodiment. [Modes for carrying out the invention]

[0027] The embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention is as follows The description is not limited to the present invention, and the form and details may not depart from the spirit and scope of the present invention. It is possible to change this in various ways. Therefore, the present invention can be described in the embodiments shown below. It should not be interpreted solely in terms of volume.

[0028] For the sake of ease of understanding, the position, size, and scope of each component shown in the drawings, etc., are as follows: The actual location, size, and range may not be represented. Therefore, the disclosed invention may not reflect the actual location, size, or range. It is not necessarily limited to the location, size, or scope disclosed in drawings, etc.

[0029] Furthermore, the ordinal numbers used in this specification, etc., as "1st," "2nd," etc., are used for convenience only. In some cases, the order of processes or stacking order may not be indicated. For example, "the first" may be written as "the second." This can be explained by appropriately replacing it with "of" or "the third of," etc. The ordinal numbers listed do not correspond to the ordinal numbers used to specify one aspect of the present invention. There are cases where this is the case.

[0030] Furthermore, in this specification and other documents, when describing the structure of the invention using drawings, the same thing is used The symbols used may be consistent across different drawings.

[0031] Furthermore, in this specification, the terms "membrane" and "layer" are interchangeable. It is possible to change the term. For example, the term "conductive layer" can be changed to the term "conductive film." It may be possible to change it. Or, for example, change the term "insulating film" to "insulating layer". In some cases, it may be possible to change the terminology to this.

[0032] Furthermore, in this specification, a fluorescent material refers to the lowest level (S1 level) of the singlet excited state. These are materials that emit light in the visible light region when they relax from a state to the ground state. Phosphorescent materials are triple-layered materials. When relaxing from the lowest level (T1 level) of the excited state to the ground state, it is visible at room temperature. It is a material that emits light in the optical region. In other words, phosphorescent materials are materials that can generate triplet excitation energy. It is one of the materials that can be converted into visible light.

[0033] Furthermore, in this specification, the emission energy of thermally activated delayed fluorescence refers to thermally activated delayed fluorescence. This refers to the emission peak (including the shoulder) at the shortest wavelength of the light. Phosphorescence emission energy or triplet excitation energy refers to the phosphorescence emission at the shortest wavelength. This refers to the emission peak (including the shoulder). Note that the above phosphorescence emission occurs at low temperatures (e.g., 10K). It can be observed by performing time-resolved photoluminescence under these conditions. .

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

[0035] (Embodiment 1) In this embodiment, a light-emitting element according to one aspect of the present invention will be described below using Figures 1 to 4. I will reveal it.

[0036] <1. Example of light-emitting element configuration 1> First, regarding the configuration of a light-emitting element according to one aspect of the present invention, use Figures 1(A), (B), and (C) to show the following: The following explains further.

[0037] Figure 1(A) is a schematic cross-sectional view of a light-emitting element 150 according to one embodiment of the present invention.

[0038] The light-emitting element 150 has an EL layer 1 provided between a pair of electrodes (electrode 101 and electrode 102) It has 00. The EL layer 100 has at least an emissive layer 113. Note that this embodiment In this explanation, electrode 101 is described as the anode and electrode 102 as the cathode, but light-emitting element 1 For 50, the opposite would also be acceptable.

[0039] Furthermore, the EL layer 100 shown in Figure 1(A) includes, in addition to the light-emitting layer 113, a hole injection layer 111, and It has a pore transport layer 112, an electron transport layer 115, and an electron injection layer 116. The configuration of 0 is not limited to the configuration shown in Figure 1(A), but may include a hole injection layer 111, a hole transport layer 112 A structure having at least one selected from the electron transport layer 115 and the electron injection layer 116. This can be done. Alternatively, the EL layer 100 reduces the carrier injection barrier, thus reducing carrier transport. A functional layer having the function of improving performance or suppressing the quenching phenomenon caused by electrodes. It may also be a configuration that includes these features.

[0040] Furthermore, Figure 1(B) is a schematic cross-sectional view showing an example of the light-emitting layer 113 shown in Figure 1(A). The light-emitting layer 113 shown in Figure 1(B) comprises a host material 121 and a guest material 122. .

[0041] The host material 121 has a singlet excitation energy level and a triplet excitation energy level. It is preferable that the difference is greater than 0 eV and less than or equal to 0.2 eV. In particular, when the host material 121 is Therefore, it is preferable that the material exhibits thermally activated delayed fluorescence at room temperature. Note that the host material 121 It may be composed of a single material or of multiple materials. As the material 122, a luminescent organic compound may be used, and the luminescent organic compound and Preferably, the material is one that can emit fluorescence (hereinafter also referred to as a fluorescent material). In the following explanation, we will describe a configuration in which a fluorescent material is used as guest material 122. Yes. Note that guest material 122 may be interpreted as a fluorescent material.

[0042] ≪1-1. Light-emitting mechanism of light-emitting elements≫ First, the light-emitting mechanism of the light-emitting element 150 will be explained below.

[0043] In one embodiment of the present invention, the light-emitting element 150 comprises a pair of electrodes (electrode 101 and electrode 102 By applying a voltage between them, electrons are released from the cathode and holes from the anode. The electrons and holes are injected into the EL layer 100, and an electric current flows. Then, the injected electrons and holes recombine. By doing so, the guest material 122 in the light-emitting layer 113 of the EL layer 100 is excited. This allows light emission to be obtained from the excited guest material 122.

[0044] Furthermore, light emission from guest material 122 is obtained through the following two processes. (α) Direct recombination process (β) Energy transfer process

[0045] ≪1-2.(α) Direct recombination process≫ Carriers (electrons and holes) recombine in the guest material 122, An excited state is formed. At this time, the excited state of the guest material 122 is a singlet excited state. Fluorescence is obtained. On the other hand, when the excited state of guest material 122 is a triplet excited state It is deactivated by heat.

[0046] In the (α) direct recombination process described above, if the fluorescence quantum yield of guest material 122 is high This allows for high luminous efficiency.

[0047] ≪1-3. (β) Energy Transfer Process≫ The carriers recombine in the host material 121, and an excited state is formed in the host material 121. This occurs. At this time, when the excited state of the host material 121 is a singlet excited state, the host material 1 The singlet excitation energy level of 21 is higher than the singlet excitation energy level of guest material 122. If the energy is also high, excitation energy is transferred from the host material 121 to the guest material 122, and the guest material The guest material 122 enters a singlet excited state. Fluorescence is obtained. Therefore, the singlet excitation energy level of the host material 121 is It is preferable that the excitation energy level is higher than that of the singlet excitation energy level of guest material 122.

[0048] Furthermore, the transition from the singlet excited state of host material 121 to the triplet excited state of guest material 122 is performed. The energy transfer is from the singlet ground state to the triplet excited state in guest material 122. Since direct transitions are prohibited, this is unlikely to become the primary energy transfer process. Omitted. That is, as shown in the following general formula (G1), energy transfer from the singlet excited state of the host material 121 to the singlet excited state of the guest material 122 is important.

[0049] , ,

[0052] , , , , G , , , H , , * , 1 , , ,

[0051] , 1 , , , , , G , H , 1 H * + 1 G → 1 H+ 1 G * (G1)

[0050] In the general formula (G1), 1 H * represents the singlet excited state of the host material 121, 1 G is the singlet ground state of the guest material 122, 1 H is the singlet ground state of the host material 121 represented by, 1 G * represents the singlet excited state of the guest material 122.

[0051] Next, in order to explain the energy transfer process of the host material 121 and the guest material 122 , Fig. 1(C) shows a schematic diagram explaining the correlation of energy levels. In Fig. 1(C), the notations and symbols are as follows. ·Host(121): Host material 121 ·Guest(122): Guest material 122 (fluorescent material) ·S H : The lowest level of the singlet excitation energy of the host material 121 ·T H : The lowest level of the triplet excitation energy of the host material 121 ·S G : The lowest level of the singlet excitation energy of the guest material 122 (fluorescent material) ·T G : The lowest level of the triplet excitation energy of the guest material 122 (fluorescent material)

[0052] Even when the excited state of the host material 121 is a triplet excited state, the S of the host material 121H but , guest material 122 S G If the value is higher than the following, fluorescence emission is obtained through the following two processes. ru.

[0053] The host material 121 has an energy difference between the singlet excitation energy level and the triplet excitation energy level. The energy difference is small, less than 0.2 eV. Therefore, the first process is as shown in Figure 1(C) As shown in A1, the host material 121 T H From inverse interterm crossover (upconversion) S H Excitation energy is transferred to it.

[0054] The second subsequent step is as shown in route E1 in Figure 1(C), host material 1 21 S H From guest material 122 S G The excitation energy is transferred to the guest material 122. It enters a singlet excited state. Fluorescence is obtained from the guest material 122 in the singlet excited state. It can be done.

[0055] The first and second processes described above can be expressed by the following general formula (G2).

[0056] 3 H * + 1 G → (reverse interterm crossover) → 1 H * + 1 G→ 1 H+ 1 G * (G2)

[0057] In addition, in the general formula (G2), 3 H * This represents the triplet excited state of the host material 121. 1 G is This represents the singlet ground state of guest material 122. 1 H *This is the singlet excited state of host material 121. This represents, 1 H represents the singlet ground state of the host material 121. 1 G * Guest material 122 This represents a singlet excited state.

[0058] As shown in the general formula (G2), the triplet excited state of the host material 121 ( 3 H * ) from the inverse term The singlet excited state of the host material 121 due to the crossover ( 1 H * ) is generated, and then the gues Singlet excited state of material 122 ( 1 G * Energy is transferred to ).

[0059] If all the energy transfer processes described above in the (β) energy transfer process occur efficiently, If both the triplet excitation energy and the singlet excitation energy of the host material 121 are efficiently obtained Singlet excited state of guest material 122 ( 1 G * Because it is converted to ), highly efficient light emission is possible. This is the result.

[0060] However, from the singlet excited state and triplet excited state of the host material 121 to the guest material 122 Before the excitation energy is transferred to the singlet excited state, the host material 121 When ghee is released as light or heat and deactivates, the luminous efficiency of the light-emitting element 150 decreases. For example, as shown by the dashed line B1 in Figure 1(C), the triplet excitation energy of the host material 121 The lowest level of ghee is T for guest material 122. G If it is lower than (in Figure 1(C), T H ' As shown, the excitation energy of guest material 122 is shown as √E3 in Figure 1(C). As such, guest material 122 TG From host material 121 T H Energy is transferred to '. In this case, T H 'and S H Because the energy difference is large, the inverse term of √A1' in Figure 1(C) Because the inter-crossing and the subsequent energy transfer processes shown in route E1 become less likely to occur, The excitation energy of the main material 122 results in thermal deactivation. Therefore, the guest material 122 The efficiency of generating singlet excited states decreases. Therefore, the T of the host material 121 H is, Guess T material 122 G It is preferable that the host material 121 is thermally activated. If the substance exhibits delayed fluorescence, the emission energy of the thermally activated delayed fluorescence of the host material 121 It is preferable that this is higher than the phosphorescence emission energy of the guest material 122.

[0061] On the other hand, as shown in the root E2 of Figure 1(C), the T of the host material 121 H From guest materials 122 T G Even when excitation energy is transferred, the excitation energy is thermally deactivated. Therefore, the fewer the energy transfer processes shown in route E2 in Figure 1(C), the better the guest material 12 This can reduce the generation efficiency of the triplet excited state and decrease thermal deactivation. Therefore, it is preferable. For this purpose, the weight ratio of the host material 121 to the guest material 122 is It is preferable that the weight ratio of host material 122 is low. Specifically, it is preferable that the weight ratio of host material 121 is 1 The weight ratio of guest material 122 is preferably greater than 0 and 0.05 or less, and more preferably... Alternatively, a value greater than 0 and less than or equal to 0.03 is preferable.

[0062] Furthermore, if the direct recombination process in guest material 122 becomes dominant, the guest material in the emissive layer This results in the generation of numerous triplet excited states (122), which leads to thermal deactivation and a loss of luminescence efficiency. In other words, the proportion of the (β) energy transfer process is greater than the (α) direct recombination process mentioned above. This reduces the thermal deactivation that occurs when the excited state of guest material 122 is a triplet excited state. This is preferable because it allows for this. For this to happen, the host material 121 and guest material 1 The weight ratio with 22 is preferably such that the weight ratio of guest material 122 is low, specifically host The weight ratio of guest material 122 to material 121 is greater than 0 and less than or equal to 0.05. A value of 0 is preferable, and more preferably a value greater than 0 and 0.03 or less is preferable.

[0063] Next, the intermolecular energy transfer between the host material 121 and the guest material 122 described above Let's explain the dominant factors. The mechanism of energy transfer between molecules is... (Förster) There are two mechanisms: the dipole-dipole interaction mechanism and the Dexter mechanism (electron exchange interaction). This has been proposed.

[0064] ≪1-4. Förster Mechanism≫ In the Förster mechanism, energy transfer does not require direct contact between molecules, and the host Energy transfer occurs through the resonance phenomenon of dipole vibrations between material 121 and guest material 122. This is due to the resonance phenomenon of dipole oscillation, which transfers energy from the host material 121 to the guest material 122. The excited host material 121 returns to the ground state, and the guest material 12 returns to the ground state. 2 enters an excited state. Note that the rate constant k of the Förster mechanism is... h*→g This is shown in equation (1). .

[0065]

number

[0066] In equation (1), ν represents the frequency, and f' h (ν) is a standard for host material 121. Emission spectra (when discussing energy transfer from singlet excited states, fluorescence spectra are used) When discussing energy transfer from triplet excited states, the phosphorescent spectrum is used. ε g (ν) represents the molar extinction coefficient of guest material 122, N represents Avogadro's number, and n represents the refractive index of the medium, and R represents the intermolecular distance between the host material 121 and the guest material 122. τ represents the measured lifetime of the excited state (fluorescence lifetime or phosphorescence lifetime), and c represents the speed of light. φ is the emission quantum yield (when discussing energy transfer from singlet excited states, this refers to the fluorescence quantum yield). The rate (or phosphorescent quantum yield when discussing energy transfer from triplet excited states) is expressed as K. 2 teeth , a coefficient representing the orientation of the transition dipole moments of the host material 121 and the guest material 122 (0 or 4) is the case. Note that in the case of random orientation, K 2 = 2 / 3

[0067] ≪1-5. Dexter Mechanism≫ In the Dexter mechanism, the host material 121 and the guest material 122 come into contact with each other to create an orbital overlap. Approaching within effective contact distance, electrons from the excited host material 121 and the ground state guest material 12 Energy transfer occurs through the exchange of electrons with 2. Note that the rate constant k of the Dexter mechanism h*→g This is shown in equation (2).

[0068]

number

[0069] In equation (2), h is Planck's constant, and K is a constant with the dimension of energy. Here, ν represents the frequency, and f' h (ν) is the normalized luminescence of the host material 121. Pectol (When discussing energy transfer from singlet excited states, use fluorescence spectra, triplet When discussing energy transfer from an excited state, the phosphorescent spectrum is represented, and ε' g (ν) The normalized absorption spectrum of guest material 122 is shown, and L represents the effective molecular radius. R represents the intermolecular distance between the host material 121 and the guest material 122.

[0070] Here, the energy transfer efficiency φ from the host material 121 to the guest material 122 is present. ET is, number It is expressed by equation (3). k r This is the luminescence process of the host material 121 (energy from singlet excited state When discussing energy transfer, use fluorescence; when discussing energy transfer from triplet excited states, use phosphorus. This represents the velocity constant of light, k n This is the non-luminescent process of the host material 121 (thermal deactivation and intersystem crossing). The rate constant is represented, and τ represents the measured lifetime of the excited state of the host material 121.

[0071]

number

[0072] From equation (3), the energy transfer efficiency φ ET In order to increase the speed of energy transfer degree constant k h*→g Increase the other competing rate constants k r +k n (=1 / τ) You'll understand that it's better if it's smaller.

[0073] ≪1-6. Concepts for Enhancing Energy Transfer≫ In both of the energy transfer processes of the above general equations (G1) and (G2), Singlet excited state of host material 121 ( 1 H * ) from guest material 122 singlet excited state ( 1 G * Since this is an energy transfer to ), the Förster mechanism (equation (1)) and Dexter Energy transfer occurs through both mechanisms (equation (2)).

[0074] First, let's consider energy transfer via the Förster mechanism. From equations (1) and (3) Eliminating τ gives the energy transfer efficiency φ ET The quantum yield φ (energy from singlet excited state) Since we are discussing energy transfer, it can be said that a higher fluorescence quantum yield is better. However, in reality, A further important factor is the emission spectrum of the host material 121 (singlet excited state or Since we are discussing their energy transfer, we are comparing the fluorescence spectrum with the absorption spectrum of guest material 122. There is a large overlap with the toll (absorption corresponding to the transition from the singlet ground state to the singlet excited state). This is preferable. Furthermore, it is preferable that the molar extinction coefficient of the guest material 122 is also high. This shows the emission spectrum of the host material 121 and the absorption spectrum of the guest material 122 that appears at the longest wavelength. This means that the collection area and the surrounding area overlap.

[0075] Next, let's consider energy transfer via the Dexter mechanism. According to equation (2), the velocity constant k h*→g To increase the size, the emission spectrum of the host material 121 (from the singlet excited state) Since we are discussing energy transfer, we are comparing the fluorescence spectrum with the absorption spectrum of guest material 122. The greater the overlap with (the absorption corresponding to the transition from the singlet ground state to the singlet excited state) You'll understand the good things.

[0076] From the above, the optimization of energy transfer efficiency is related to the emission spectrum of the host material 121. This is achieved by the overlap of the absorption band that appears on the longest wavelength side of guest material 122. .

[0077] Therefore, one aspect of the present invention provides an energy transfer mechanism that can efficiently transfer energy to the guest material 122. A light-emitting element is provided using a host material 121 that functions as a gas donor. The material 121 has a singlet excitation energy level and a triplet excitation energy level that are close together. It has the characteristic of being present. Specifically, the singlet excitation energy level of the host material 121 and It is preferable that the difference from the triplet excitation energy level is greater than 0 eV and less than or equal to 0.2 eV. By using this configuration, the transition of the host material 121 from the triplet excited state to the singlet excited state is achieved. Reverse intersystem crossing is likely to occur. Therefore, the generation effect of singlet excited states in the host material 121 is The rate can be increased. Furthermore, the energy from the singlet excited state of the host material 121 can be increased. This facilitates energy transfer to the singlet excited state of the receptor guest material 122. To do this, the emission spectrum of the host material 121 (here, exhibiting thermally activated delayed fluorescence) is required. (Emission spectrum of the functional material) and absorption spectrum of guest material 122 that appears at the longest wavelength. It is preferable for the band and to overlap. This will generate the singlet excited state of guest material 122. It can increase efficiency.

[0078] Furthermore, in the light-emitting element 150 according to one aspect of the present invention, the triplet excitation of the host material 121 The energy level is higher than the triplet excitation energy level of guest material 122, therefore the host Transition of material 121 from triplet excited state to singlet excited state, and singlet excited state of host material 121 Energy transfer from the singlet excited state to the singlet excited state of guest material 122 is likely to occur. Therefore, thermal deactivation in the light-emitting element 150 is reduced, and the luminous efficiency of the light-emitting element 150 is improved. This can enhance the effect. Also, the host material 121 is a substance that exhibits thermally activated delayed fluorescence at room temperature. In some cases, the emission energy of the thermally activated delayed fluorescence is equal to the phosphorescent emission energy of the guest material 122. Because it is higher than energy, the transition of host material 121 from the triplet excited state to the singlet excited state occurs. , and the transition from the singlet excited state of the host material 121 to the singlet excited state of the guest material 122 Energy transfer occurs efficiently. Therefore, thermal deactivation in the light-emitting element 150 is reduced. Therefore, the luminous efficiency of the light-emitting element 150 can be increased.

[0079] ≪1-7. Materials≫ In the light-emitting layer 113, the host material 121 may be composed of one type of material, or multiple materials may be used. It may be composed of multiple materials. For example, the host material 121 may be composed of one type of material. If so, the following materials can be used.

[0080] First, there are fullerenes and their derivatives, acridine derivatives such as proflavin, and eosin. It can also contain magnesium (Mg), zinc (Zn), cadmium (Cd), and tin (Sn). Metal-containing materials including platinum (Pt), indium (In), or palladium (Pd), etc. Examples include porphyrins. For example, the following structural formula is shown for the metal-containing porphyrin. The protoporphyrin-tin fluoride complex (SnF2(Proto IX)) is used, and the mesoporphyrin Rufirin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-f Tin oxide complex (SnF2(Hemato IX)), coproporphyrin tetramethyl Stell-tin fluoride complex (SnF2(Copro III-4Me)), octaethyl phosphate Ruffin-tin fluoride complex (SnF2(OEP)), Ethioporphyrin-tin fluoride Complex (SnF2(Etio I)), Octaethylporphyrin-Platinum Chloride Complex (PtC Examples include l2OEP.

[0081] [ka]

[0082] Furthermore, the host material 121, which is composed of one type of material, is shown in the following structural formula. 2-(biphenyl-4-yl)-4,6-bis(12-phenylindoro[2,3-a] Carbazole-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 2- {4-[3-(N-phenyl-9H-carbazole-3-yl)-9H-carbazole- 9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCz) PTzn), 2-[4-(10H-phenoxazine-10-yl)phenyl]-4,6- Diphenyl-1,3,5-triazine (abbreviation: PXZ-TRZ), 3-[4-(5-phenyl Nyl-5,10-dihydrophenazine-10-yl)phenyl]-4,5-diphenyl- 1,2,4-Triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H -Acrydin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), S[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviated) Name: DMAC-DPS), 10-phenyl-10H,10'H-spiro[acridine-9 ,9'-Anthracene]-10'-one (abbreviation: ACRSA), etc., and heterocyclic compounds having a π-electron-excessive heteroaromatic ring and a π-electron-deficient heteroaromatic ring can also be used. Since the heterocyclic compound has a π-electron-excessive heteroaromatic ring and a π-electron-deficient heteroaromatic ring, its electron transport property and hole transport property are high, which is preferable. Note that a substance in which a π-electron-excessive heteroaromatic ring and a π-electron-deficient heteroaromatic ring are directly bonded has both strong donor property of the π-electron-excessive heteroaromatic ring and acceptor property of the π-electron-deficient heteroaromatic ring, and the difference between the singlet excited state level and the triplet excited state level is small, so it is particularly preferable.

[0083]

Chemical formula

[0084] ​​​​​​​​​​​​​​​​​​​​​​​​Bis(3-methylphenyl)-N,N’-bis[3-(9-phenyl-9H-fluorene -9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPr n), N,N’-bis[4-(9H-carbazol-9-yl)phenyl]-N,N’- diphenylstilbene-4,4’-diamine (abbreviation: YGA2S), 4-(9H-carb azol-9-yl)-4’-(10-phenyl-9-anthryl)triphenylamine( abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4’-(9,10-dip enyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-dip enyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol- 3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetra(tert -butyl)perylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)-4’ -(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCB APA), N,N’’-(2-tert-butylanthracene-9,10-diyl-di-4 ,1-phenylene)bis[N,N’,N’-triphenyl-1,4-phenylenediamine (abbreviation: DPABPA), N,9-diphenyl-N-[4-(9,10-diphenyl- 2-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: 2PCAPPA ), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N’,N’ -triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), N,N,N’ ,N’,N’’,N’’,N’’’,N’’’-octaphenyldibenz[g,p]chry sene-2,7,10,15-tetraamine (abbreviation: DBC1), coumarin 30, N-(9 ,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazole-3 -amine (abbreviation: 2PCAPA), N-[9,10-bis(1,1'-biphenyl-2- [Iyl)-2-anthryl]-N,9-diphenyl-9H-carbazole-3-amine (abbreviated) Name: 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-bi Su(1,1'-biphenyl-2-yl)-N-[4-(9H-carbazole-9-yl) Phenyl]-N-phenylanthracene-2-amine (abbreviation: 2YGABPhA), N, N,9-triphenylanthracene-9-amine (abbreviation: DPhAPhA), coumarin 6 Coumarin 545T, N,N'-diphenylquinacridone (abbreviation: DPQd), rubrene , 5,12-bis(1,1'-biphenyl-4-yl)-6,11-diphenyltetrace n (abbreviation: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl} -6-methyl-4H-pyran-4-ylidene)propanedinitrile (abbreviation: DCM1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ ij]Quinolysin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedin Toryl (abbreviation: DCM2), N,N,N',N'-tetrakis(4-methylphenyl) Tracene-5,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N, N,N',N'-Tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluora Nten-3,10-diamine (abbreviation: p-mPhAFD), 2-{2-isopropyl-6 -[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H -Benzo[ij]quinoridine-9-yl)ethenyl]-4H-pyran-4-ylidene} Ropanedinitrile (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1 ,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[i j]Quinoridine-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinite Lyl (abbreviation: DCJTB), 2-(2,6-bis{2-[4-(dimethylamino)pheny [Lu]ethenyl-4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDC) M), 2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2, 3,6,7-Tetrahydro-1H,5H-benzo[ij]quinoridine-9-yl)ethen [Lu]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJTM), 5,10,15,20-tetraphenylbisbenzo[5,6]indeno[1,2,3-c Examples include perylene [d:1',2',3'-lm].

[0086] The light-emitting layer 113 is produced by vapor deposition (including vacuum deposition), inkjet, coating, etc. It can be formed by methods such as labia printing.

[0087] <2. Example of light-emitting element configuration 2> Next, for configurations different from those shown in Figures 1(B) and 1(C), use Figures 2(A) and 2(B). The following explains this.

[0088] FIG. 2(A) is a schematic cross-sectional view showing an example of the light-emitting layer 113 shown in FIG. 1(A). FIG. 2( The light-emitting layer 113 shown in A) has a host material 121 and a guest material 122, and the host material 121 has an organic compound 121_1 and an organic compound 121_2.

[0089] The organic compound 121_1 and the organic compound 121_2 are preferably a combination that forms an exciplex (also called an exciplex). The exciplex has a property that the difference between the singlet excitation energy level and the triplet excitation energy level is very likely to be small, so that the transition from the triplet excited state to the singlet excited state (reverse intersystem crossing) is likely to occur. Also, either one of the organic compound 121_1 or the organic compound 121_2 functions as the host material of the light-emitting layer 113, and the other of the organic compound 121_1 or the organic compound 121_2 functions as the assist material of the light-emitting layer 113. In the following description, the organic compound 12 1_1 will be described as the host material and the organic compound 121_2 as the assist material.

[0090] Even when a host material is used such that the organic compound 121_1 and the organic compound 121_2 form a combination that forms an exciplex, the light emission from the guest <00009x83>material 122 can be obtained by the following two processes. <00009x86>

[0091] (α) Direct recombination process (β) Energy transfer process (β) Energy transfer process

[0091] Regarding the (α) direct recombination process, it is the same as the process described in 1-2. above, so the description here is omitted.

[0092] <0000xx94>≪2-1. (β) Light emission mechanism via energy transfer process≫ Organic compound 121_1 and organic compound 121 form an excitation complex in the light-emitting layer 113. The combination with _2 is limited to any combination that can form an excited complex. There is no definitive answer, but one material is a hole-transporting material and the other is an electron-transporting material. It is more preferable to do so. In this case, it is easier to form a donor-acceptor type excited state. This allows for the efficient formation of excited complexes. Furthermore, it enables the formation of electron transport in materials that have hole transport properties. By combining with materials that have properties, organic compound 121_1 and organic compound 121_2 When configuring a combination, the carrier balance can be easily controlled by the mixing ratio. This can be achieved. Specifically, the ratio of hole-transporting materials to electron-transporting materials is 1:9. A range of 9:1 (weight ratio) is preferred. Furthermore, having this configuration makes it easy to carry bulk Because the tensile strength can be controlled, the recombination region can also be easily controlled.

[0093] Furthermore, the excited complex formed by organic compound 121_1 and organic compound 121_2 The difference between the singlet excitation energy level and the triplet excitation energy level is greater than 0 eV, which is 0.2 eV. It is preferable that it is V or less. With the above configuration, the triplet excitation energy level of the excited complex A transition from this to the singlet excitation energy level (reverse intersystem crossing) is likely to occur. Therefore, excitation This can increase the efficiency of generating the singlet excited state of the host material 121, i.e., the initiating complex.

[0094] Furthermore, the emission spectrum of the host material 121 (here, organic compound 121_1 and The emission spectrum of the excited complex formed by the mechanical compound 121_2 and guest material 12 It is preferable that the absorption band appearing on the longest wavelength side of 2 overlaps with . With the above configuration, Energy transfer from the singlet excited state of material 121 to the singlet excited state of guest material 122 Dynamics are more likely to occur. Therefore, the efficiency of generating singlet excited states of guest material 122 is increased. This allows for increased luminescence efficiency.

[0095] Here, in order to explain the energy transfer process of the excited complex, Figure 2(B) shows the energy levels A schematic diagram illustrating the correlation of the positions is shown. Note that the notation and symbols in Figure 2(B) are as follows: It is. ·Host(121): Host material (organic compound 121_1) • Guest (122): Guest material 122 (fluorescent material) • Assist: Host material (organic compound 121_2) ·S H : The lowest level of singlet excitation energy of the host material (organic compound 121_1) ·T H : The lowest level of triplet excitation energy of the host material (organic compound 121_1) ·S E : The lowest level of singlet excitation energy of the excited complex ·T E : The lowest level of triplet excitation energy of the excited complex ·S G : The lowest level of singlet excitation energy of guest material 122 (fluorescent material) ·T G : The lowest level of triplet excitation energy for guest material 122 (fluorescent material)

[0096] When carriers (holes and electrons) are transported to the light-emitting layer 113, the organic compound 121_1 and In organic compound 121_2, one accepts a hole and the other accepts an electron, and they are in close proximity. This quickly forms an excited complex. Alternatively, when one enters an excited state, the other quickly... It forms an excited complex by interacting with the substance. Therefore, the excited complex in the light-emitting layer 113 Most of the screwdrivers exist as an excited complex. The excited complex has a smaller band gap than either of the organic compound 121_1 and the organic compound 121_2. Therefore, by forming the excited complex, the driving voltage can be lowered.

[0097] In addition, since the organic compound 121_1 and the organic compound 121_2 can form a donor-acceptor type excited state, the S of the excited complex E and the T of the excited complex E are close to each other.

[0098] When the excited state of the excited complex is a singlet excited state, as shown in route E4 of Fig. 2(B), the S of the excited complex E to the S of the guest material 122 G the excitation energy moves, and the guest material 12 2 becomes a singlet excited state. Fluorescent emission can be obtained from the guest material 122 that has become a singlet excited state. That is, as shown in the following general formula (G3), energy transfer occurs from the singlet excited state of the excited complex to the singlet excited state of the guest material 122.

[0099] 1 [H-A] * + 1 G → 1 H+ 1 A+ 1 G * (G3)

[0100] In the general formula (G3), 1 [H-A] * represents the singlet excited state of the excited complex formed by the organic compound 121_1 and the organic compound 121 _2, 1 G represents the singlet ground state of the guest material 122, 1 H represents the singlet ground state of the organic compound 121_1, 1 A represents the organic compound​​ This represents the singlet ground state of object 121_2, 1 G * This represents the singlet excited state of guest material 122. vinegar.

[0101] Furthermore, even if the excited state of the excited complex is a triplet excited state, the S of the excited complex E However, guest material Price 122 S G If the value is higher than the following, fluorescence emission is obtained through the following two processes.

[0102] As the first step, as shown in route A2 of Figure 2(B), the T of the excited complex E From the inverse term Through inter-crossing (upconversion), S E Excitation energy is transferred to it.

[0103] As the second subsequent step, as shown in route E4 of Figure 2(B), the S of the excited complex E From guest material 122 S G The excitation energy is transferred, and guest material 122 undergoes singlet excitation. The system enters an excited state. Fluorescence is obtained from guest material 122, which is in a singlet excited state.

[0104] Furthermore, the processes of Route A2 and Route E4 described above are referred to in this specification, etc., as ExSET. (Exciplex-Singlet Energy Transfer) or ExE When referred to as F (Exciplex-Enhanced Fluorescence) There is.

[0105] The first and second processes described above can be expressed by the following general formula (G4).

[0106] 3 [HA] * + 1 G → (reverse interterm crossover) → 1 [HA] * +1 G→ 1 H+ 1 A+ 1 G * (G4)

[0107] In addition, in the general formula (G4), 3 [HA] * This is organic compound 121_1 and organic compound 121 This represents the triplet excited state of the excited complex formed with _2. 1 G is a singlet guest material 122. Represents the ground state, 1 [HA] * It is formed by organic compound 121_1 and organic compound 121_2. This represents the singlet excited state of the resulting excited complex. 1 H is in the singlet base state of organic compound 121_1. To express a state, 1 A represents the singlet ground state of organic compound 121_2, 1 G * Guest material 1 This represents the 22 singlet excited states.

[0108] As shown in the general formula (G4), the triplet excited state of the excited complex ( 3 [HA] * ) from the inverse term Crossover leads to the singlet excited state of the excited complex ( 1 [HA] * ) is generated, and then, Singlet excited state of material 122 ( 1 G * Energy is transferred to ).

[0109] By configuring the host material 121 as described above, the above (β) energy transfer process is made efficient. It occurs well, and both the singlet and triplet excitation energies of the excited complex are efficiently obtained. Because the guest material 122 is converted to a singlet excited state, the guest material 122 in the light-emitting layer 113 This makes it possible to efficiently obtain light emission from (fluorescent materials).

[0110] However, before the excitation energy is transferred from the excited complex to the guest material 122, the excited complex If the excitation energy is released as light or heat and the element becomes inactive, the luminescence efficiency decreases. There are cases where this occurs. For example, as shown in the root E5 of Figure 2(B), the T of the excited complex E From guests Material 122 T G When excitation energy is transferred, the excitation energy is thermally deactivated. Therefore, the weight ratio of the guest material 122 to the host material 121 is greater than 0. A value of less than 0.05 is preferable, and more preferably a value greater than 0 and less than or equal to 0.03 is preferable. .

[0111] Furthermore, as shown by the dashed line B2 in Figure 2(B), the T of the host material 121 H , in other words, organic transformation The triplet excitation energy level of compound 121_1 or organic compound 121_2 is the same as that of the excited complex. T E If it is lower than (in Figure 2(C), T H As shown by ', it is shown in the route E6 in Figure 2(B). Sea urchin, T of the excited complex E From host material 121 T H After energy is transferred to ', the excitation E Energy is deactivated by heat. Therefore, organic compound 121_1 and organic compound 121_2 The triplet excitation energy level is the T of the excited complex. E It is preferable that it be higher than that. Therefore, it is preferable because reverse intersystem crossing occurs efficiently in the excited complex.

[0112] Furthermore, the excited complex is S E and T E Because they are in close proximity, T E T is a guest material 122 G Lower In that case, S E The energy level of TG It drops significantly to the vicinity or below. As a result, S E From guest material 122 S G Energy transfer to (Route E4) becomes difficult. Therefore, fluorescence from guest material 122 becomes difficult to obtain. Consequently, the T of the excited complex E is, Guess T material 122 G A higher value is preferable.

[0113] From the above, if the excited complex exhibits thermally activated delayed fluorescence at room temperature, then organic compound 121_ The phosphorescence emission energy of 1 and organic compound 121_2 is the emission of thermally activated delayed fluorescence of the excited complex. It is preferable that it is higher than the light energy. Also, the emission energy of the thermally activated delayed fluorescence of the excited complex The energy is preferably higher than the phosphorescence emission energy of the guest material 122.

[0114] ≪2-2. Materials≫ In the light-emitting layer 113, the host material 121 is composed of organic compound 121_1 and organic compound 12 When formed by 1_2, that is, when the host material 121 is composed of two types of materials, For example, the following materials can be used.

[0115] Furthermore, organic compound 121_1 and organic compound 121_2 are two types that form excited complexes. It is preferable to use a combination of organic compounds. In this case, various carrier transport materials While these can be used as appropriate, in order to efficiently form excited complexes, electron-receiving and Pyramid materials (materials with electron transport properties) and materials that readily accept holes (materials with hole transport properties) It is particularly preferable to combine it with (the material).

[0116] Because combining electron-transporting materials with hole-transporting materials is exciting When used as a host material for forming a complex, it is a material that has electron transport properties and hole transport properties. By adjusting the mixing ratio of the materials, the balance of hole and electron carriers in the light-emitting layer can be optimized. Optimization becomes easier. The balance of hole and electron carriers in the light-emitting layer is optimized. This suppresses the bias in the region where electron-hole recombination occurs within the light-emitting layer. By suppressing the bias in the region where the collision occurs, the reliability of the light-emitting element can be improved.

[0117] Examples of materials that readily accept electrons (materials with electron transport properties) include π-electron-deficient complex aromatics. Fragrance group compounds and metal complexes can be used. Specifically, bis(10-hydroxybenzo [h]Quinolinato)Beryllium(II) (abbreviation: BeBq2), bis(2-methyl-8- (Quinolinolato)(4-phenylphenolato)aluminum(III) (abbreviation: BAlq) , bis(8-quinolinolato)zinc(II) (abbreviation: Znq), bis[2-(2-benzoo Xazolyl)phenolate]zinc(II) (abbreviation: ZnPBO), bis[2-(2-benzo Metal complexes such as thiazolyl)phenolate]zinc(II) (abbreviation: ZnBTZ), and 2-( 4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadia Zole (abbreviation: PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-ter t-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5 -(p-tert-butylphenyl)-1,3,4-oxadiazole-2-yl]ben Zen (abbreviation: 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-benzoimidazole) (Abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-f Azole skeletons such as phenyl-1H-benzoimidazole (abbreviation: mDBTBIm-II) Heterocyclic compounds having, or 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzothiophene Nzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(gibe [Nzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline ( Abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazole-9-yl) Biphenyl-3-yl[f,h]quinoxaline (abbreviation: 2mCzBPDBq) , 4,6-bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4, 6mPnP2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimid Heterocyclic compounds having a diazine skeleton, such as n (abbreviation: 4,6mDBTP2Pm-II) and , 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol [Il-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: P Heterocyclic compounds having a triazine skeleton such as CCzPTzn, and 3,5-bis[3-( 9H-carbazole-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy), 1, 3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), etc. Examples include heterocyclic compounds having a pyridine skeleton. Among those mentioned above, diazine skeletons and Heterocyclic compounds with a lyazine skeleton or a pyridine skeleton are highly reliable. It is good and preferable. In particular, the diazine (pyrimidine and pyrazine) skeleton and the triazine skeleton The heterocyclic compounds possess high electron transport properties and contribute to reducing the driving voltage. Furthermore, reliability is... In order to have good and high triplet excitation energy levels, it must have a condensed heterocycle skeleton, The condensed heterocyclic skeleton preferably has a diazine skeleton. Alternatively, a carbazole skeleton. It is preferable that the fused heterocyclic skeleton has a diazine skeleton, and that the fused heterocyclic skeleton has a diazine skeleton. Alternatively, it has a carbazole skeleton and a fused heterocyclic skeleton, wherein the fused heterocyclic skeleton is diazi It has a skeleton, and the carbazole skeleton and the condensed heterocyclic skeleton are bonded via arylene groups. Preferably, the structure has such an arrangement, with an allerene group at the 9-position of the carbazole skeleton via It is particularly preferable to have a bonding structure. As a condensed heterocyclic skeleton having the diazine skeleton These are quinoxaline skeleton, quinazoline skeleton, benzoquinoxaline skeleton, and benzoquinazoline skeleton. Dibenzoquinoxaline skeleton, dibenzoquinazoline skeleton, or benzoflopyrimidine A skeletal structure is preferable.

[0118] Examples of materials that readily accept holes (materials with hole transport properties) include π-electron-rich complex aromatics. Fragrance group or aromatic amines can be suitably used. Specifically, 2-[N-(9- Phenylcarbazole-3-yl)-N-phenylamino]spiro-9,9'-bifluor Len (abbreviation: PCASF), 4,4'-bis[N-(1-naphthyl)-N-phenylamine [N]biphenyl (abbreviation: NPB), N,N'-bis(3-methylphenyl)-N,N'- diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4 '-Bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenylamino] Biphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluorene-9- Il)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9-phenyl (Fluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-phenyl -4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol) Lu-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl) -4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-cal Bazole-3-yl)triphenylamine (abbreviation: PCBNBB), 9,9-dimethyl- N-phenyl-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl] -Fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl Nyl-9H-carbazole-3-yl)phenyl]-spiro-9,9'-bifluolene- 2-amine (abbreviation: PCBASF), N-(1,1'-biphenyl-4-yl)-N-[ 4-(9-phenyl-9H-carbazole-3-yl)phenyl]-9,9-dimethyl- It has an aromatic amine skeleton such as 9H-fluoren-2-amine (abbreviation: PCBBiF) Compounds such as 1,3-bis(N-carbazolyl)benzene (abbreviated as mCP), 4,4'-di (N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenyl) Phenyl)-9-phenylcarbazole (abbreviation: CzTP), 9-phenyl-9H-3- (9-phenyl-9H-carbazol-3-yl)carbazole (abbreviation: PCCP), etc. Compounds having a carbazole skeleton, or 4,4',4''-(benzene-1,3,5- (Lyyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,8-diphenyl -4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophone phenyl (abbreviation: DBTFLP-III), 4-[4-(9-phenyl-9H-fluorene- 9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV) Compounds having a thiophene skeleton such as, and 4,4',4''-(benzene-1,3,5- Triyl)tri(dibenzofuran) (abbreviation: DBF3P-II), 4-{3-[3-(9 -phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation) Examples include compounds having a furan skeleton such as :mmDBFFLBi-II. Among them, compounds with aromatic amine skeletons and compounds with carbazole skeletons are reliable. It is preferable because it has good performance, high hole transportability, and contributes to reducing the drive voltage. In order to have high triplet excitation energy levels, it is preferable to have a carbazole skeleton. It is preferable to have one aromatic amine skeleton. Alternatively, carbazo It has a carbazole skeleton and an aromatic amine skeleton, and the carbazole skeleton and the aromatic amine skeleton are carbazole It is preferable that the structure has a bond at position 9 of the carbazole skeleton, It is particularly preferable to have a structure in which a bond is formed at the 9-position via an arylene group.

[0119] Organic compound 121_1 and organic compound 121_2 are limited to the compounds described above. It is a combination that can transport carriers and form an excited complex, and the excited complex The emission is due to the longest wavelength absorption band in the absorption spectrum of the luminescent material (singlet of the luminescent material). It is sufficient that it overlaps with the absorption corresponding to the transition from the ground state to the singlet excited state, and other materials You may also use this.

[0120] Furthermore, in the light-emitting layer 113 shown in Figure 2(A), the guest material 122 is used. The materials that can be produced are the same as guest material 122 shown in 1-7, so the explanation is not provided here. (This part is omitted.)

[0121] ≪2-3. Relationship between the luminescence energy of the excited complex and the triplet energy level of the host material≫ Here, a combination of organic compounds that form an excited complex according to one aspect of the present invention, and the excited complex The relationship between the luminescence energy of the body and the triplet energy levels of the host material is explained in detail below. explain.

[0122] Emission spectra of thin films of individual organic compounds, and combinations of two different organic compounds. The emission spectra of the mixed film are shown in Figures 3(A) and (B). Note that compounds 1 to 4, Figure 3(A) shows the emission spectra of compounds 5 to 7. The emission spectra of excited complexes 4 to 6 are shown in Figure 3(B), respectively.

[0123] Also, in Figure 3(A)(B), compound 1 is 2-[3-(dibenzothiophen-4-yl) Phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), compound Item 2 is 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4, 6mDBTP2Pm-II), compound 3 is 2,7-bis[N-(4-diphenylaminophosphate) [phenyl)-N-phenylamino]-spiro-9,9'-bifluorene (abbreviation: DPA2S) F), compound 4 is 2-[N-(9-phenylcarbazole-3-yl)-N-phenyl Mino-spiro-9,9'-bifluorene (abbreviation: PCASF), compound 5 is 4,6-bis [3-(9H-carbazole-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP) 2PM), compound 6 is N-(4-biphenyl)-N-(9,9-dimethyl-9H-fluorinated Len-2-yl)-9-phenyl-9H-carbazole-3-amine (abbreviation: PCBiF) ), compound 7 is 9-phenyl-9H-3-(9-phenyl-9H-carbazole-3- (L)Carbazole (abbreviation: PCCP), compound 8 is 4,4'-bis[N-(1-naphthyl Emission spectrum of thin films with )-N-phenylamino]biphenyl (abbreviation: NPB) The structural formulas and abbreviations of compounds 1 through 8 are shown below.

[0124] [ka]

[0125] The emission spectrum represented by the excited complex 1 shown in Figure 3(A) is a mixture of compound 1 and compound 3. This is the result of measuring the luminescence of the composite film. In other words, one of compound 1 and compound 3 is an organic compound. 121_1 corresponds to the other, and the other to the organic compound 121_2. Similarly, the excited complex 2 is represented by The light spectrum shows the emission of the mixed film of compound 1 and compound 4, represented by the emission complex 3. The vector is the result of measuring the luminescence of a mixed film of compound 2 and compound 4. The spectrum is obtained by irradiating a thin film of each compound individually or a mixed film of two compounds with ultraviolet light. The luminescence obtained was measured. Note that PL-EL measurement was used to measure the emission spectrum. The apparatus (manufactured by Hamamatsu Photonics) was used. The thin film was 50 nm thick on a quartz substrate. Each compound was formed by vacuum deposition. The mixed thin film was formed by two different compounds. These were formed by a vapor deposition method (co-evaporation) in which each element was simultaneously evaporated from different evaporation sources.

[0126] Excited complex 1 and excited complex 2 both use compound 1, but in addition to forming the excited complex, The compounds are different. Therefore, the emission spectral peaks of compound 3 and compound 4 are different. Even if there is almost no difference, the wavelength of the emission spectral peak of excited complex 1 is 579 nm, The emission spectral peaks of the progenitor complex 2 have wavelengths of 543 nm, and these peaks are 30 nm. The above differences exist. This is because excited complex 1 and excited complex 2 are of the donor-acceptor type. This is because it is an excited complex. In other words, the singlet excitation energy of the excited complex is the same as that of two organic complexes. Highest Occupied Molecular Orbital ( (also called bital or HOMO) and Lowest Unoccupied Orbit The higher of the Molecular Orbitals (also called LUMO) This corresponds to the energy difference between the lower LUMO and the lower LUMO. Therefore, one compound is different from the other. By making it a substance, the energy levels of the HOMO or LUMO that form the excited complex change. Therefore, the emission wavelength of the excited complex can be changed.

[0127] Furthermore, although both excited complex 2 and excited complex 3 use compound 4, they form excited complexes. The other substance is different. The wavelength of the emission spectral peak of excited complex 3 is 528 The difference is in nm, and there is a 15 nm difference in the emission spectral peaks of excited complex 2 and excited complex 3. In this way, by simply changing one of the compounds that forms the excited complex, the luminescence of the excited complex can be altered. The wavelength can be easily changed.

[0128] Furthermore, since the wavelength of the emission spectrum peak of excited complex 1 is 579 nm, excited complex 1 In addition, a light-emitting material having the function of emitting yellow to red light is mixed as guest material 122. It is preferable to use it in a light-emitting device. Furthermore, the emission spectrum of excitation complex 2 and excitation complex 3 The wavelengths of Lupek are 543 nm and 528 nm, respectively, therefore, excited complex 2 or In the starting complex 3, a luminescent material having the function of emitting green to red light is used as guest material 122. It is preferable to mix them and use them in a light-emitting device.

[0129] The emission spectrum represented by the excited complex 4 shown in Figure 3(B) is a mixture of compound 5 and compound 6. This is the result of measuring the luminescence of the composite film. In other words, one of compound 5 and compound 6 is an organic compound. 121_1 corresponds to the other, and the other to the organic compound 121_2. Similarly, the excited complex 5 is represented by The light spectrum shows the emission of the mixed film of compound 5 and compound 7, represented by the emission of the excitation complex 6. The vector is the result of measuring the luminescence of a mixed film of compound 5 and compound 8. Pectol is obtained by irradiating a thin film of each compound individually or a mixed film of two compounds with ultraviolet light. The resulting luminescence was measured.

[0130] Excited complexes 4 through 6 all use compound 5, but they form excited complexes. The other substance is different. Therefore, the emission spectra of excited complexes 4 to 6 are different. A difference has been observed. In this way, by simply changing one of the compounds that forms the excited complex, The emission wavelength of the excited complex can be easily changed.

[0131] The wavelengths of the emission spectral peaks of excited complex 4 and excited complex 6 are 545n, respectively. Because the wavelength is 516 nm, either excited complex 4 or excited complex 6 emits green to red light. It is preferable to mix a functional light-emitting material as a guest material 122 and use it in a light-emitting device. Therefore, the wavelength of the emission spectral peak of excited complex 5 is 488 nm, A luminescent material having the function of emitting blue to red light is mixed into complex 5 as guest material 122. In combination, it is preferable to use it in a light-emitting element.

[0132] Next, the phosphorescent emission spectra of compounds 1 to 8 are shown in Figures 4(A) and 4(B). The phosphorescence emission spectra shown in A) and (B) are obtained under low temperature (10K) conditions, with an oscillation wavelength of 3 A 25nm ultraviolet laser (He-Cd laser) was irradiated onto thin films of each compound, and time-resolved photophotography was performed. These are the results measured using the luminescence method. The measurement was performed using a micro-PL device (Lab). A RAM HR-PL (Horiba, Ltd.) was used, and a CCD detector was employed as the detector. Furthermore, the thin film is formed by vacuum depositing each compound onto a quartz substrate to a thickness of 50 nm. I did it.

[0133] Furthermore, from the shortest wavelength phosphorescence peak (including the shoulder) of the phosphorescence emission spectrum... The results of determining the phosphorescence emission energy are shown in Tables 1 and 2. Note that in the excited complex, Because the triplet excitation energy level and the singlet excitation energy level are close to each other, Separation of phosphorescent emission spectra and fluorescence emission spectra (emission spectra of thermally activated delayed fluorescence) This is difficult. Therefore, the phosphorescence emission energies of the excited complexes in Tables 1 and 2 are, The emission spectral peak of the complex (the emission spectral peak of thermally activated delayed fluorescence) is phosphorescent. Assuming it is identical to the spectral peak, the phosphorescent emission energy is obtained from the peak of the emission spectrum. This is the result of calculating the following: the emission energy of thermally activated delayed fluorescence of the excited complex and phosphorescence. The luminescence energy is considered to be nearly identical.

[0134] [Table 1]

[0135] [Table 2]

[0136] The phosphorescence emission energy of excited complexes 1 to 5 shown in Tables 1 and 2 (thermal activation delayed fireflies) The emission energy of light is the phosphorescent emission energy of the compounds that form each excitation complex. In comparison, the energy is lower. That is, the phosphorescence emission energy of excited complex 1 (thermal activation delay) The phosphorescent emission energies of compound 1 and compound 3 are higher than the fluorescence emission energy. From the phosphorescence emission energy of excited complex 2 (emission energy of thermally activated delayed fluorescence), compound 1 Furthermore, the phosphorescence emission energy of compound 4 is higher, and the phosphorescence emission energy of excited complex 3 (thermal activity The phosphorescent emission energy of compound 2 and compound 4 is greater than the emission energy of delayed-activation fluorescence. The phosphorescence emission energy of excited complex 4 (emission energy of thermally activated delayed fluorescence) is high, The phosphorescence emission energy of compounds 5 and 6 is higher, and the phosphorescence emission energy of excited complex 5 is higher. - (Emission energy of thermally activated delayed fluorescence) The phosphorescent emission energy of compound 5 and compound 7 Ghee is more expensive.

[0137] In other words, excited complexes are formed from the triplet energy levels of excited complexes 1 to 5. The triplet energy levels of each compound are higher. Therefore, E6 in Figure 2(B) The energy transfer process shown is from the triplet excitation energy level of the excited complex The triplet excitation energy levels of organic compound 121_1 and organic compound 121_2 No energy transfer occurs to the triplet excitation energy level, and the triplet excited state of the excited complex does not occur. Thermal deactivation can be suppressed.

[0138] Therefore, the excitation energy of the triplet excited state of the excited complex is determined by reverse intersystem crossing. The excited complex generated by this process proceeds to the singlet excited state of the guest material 122, which is then efficiently excited. Energy can be transferred to the state. Therefore, the luminescence from guest material 122 can be efficiently transferred. It can be obtained easily.

[0139] On the other hand, the phosphorescence emission energy of excited complex 6 shown in Table 2 is one of the substances that form the excited complex. It is higher than the phosphorescence emission energy of compound 8, that is, the triplet energy of excited complex 6. From the Ghee level, the triplet energy level of compound 8, one of the substances that form an excited complex, The latter is lower. Therefore, the energy transfer process shown in E6 of Figure 2(B), the three excitation complexes, From the doublet excitation energy level, the triplet excitation of organic compound 121_1 that forms an excited complex Energy level or energy transfer of organic compound 121_2 to triplet excitation energy level Dynamics occur, and thermal deactivation of the triplet excited state of the excited complex may occur. Therefore, In order to prevent this, organic compound 121_1 and organic compound 121_ form an excited complex. The triplet excitation energy level of 2 is preferably higher than the triplet excitation energy of the excited complex. Therefore, to do so, the triplet excitation energy of organic compound 121_1 that forms the excited complex is The difference between the energy level and the triplet excitation energy level of organic compound 121_2 is less than 0.4 eV. It is preferable to have one.

[0140] Furthermore, the lowest triplet excitation energy level of guest material 122 is shown in Table 3.

[0141] [Table 3]

[0142] To determine the lowest level of triplet excitation energy shown in Table 3, the lowest level of guest material 122 was determined. The most stable structure in the low triplet excited state and the most stable structure in the singlet ground state are determined by density The calculations were performed using functional theory (DFT). Furthermore, vibration analysis was performed for each most stable structure. This process calculates the difference in the lowest vibrational energy between the lowest triplet excited state and the lowest singlet ground state. By doing so, the lowest level of triplet excitation energy was calculated. Note that the quantum chemical calculation program Gaussian09 was used as the RAM. The basis set was 6-311G(d Using p(,), the functional B3LYP was used. The calculations were performed on a high-performance computer. The procedure was performed using (SGI Corporation's ICE X).

[0143] The triplet excitation energy levels of the compounds shown in Table 3 are all the same as the excitation complexes shown in Tables 1 and 2. This energy level is lower than the triplet excitation energy levels of body 1 to excited complex 5. Therefore, The compounds shown in Table 3 were used as guest material 122, and the excited complexes 1 to 5 shown above were used. By using the compound to be formed as the host material 121, the roots A2 and L in Figure 2(B) Energy transfer as shown in E4 becomes more likely, and the energy is efficiently transferred from the excited complex to the guest material 122. It can transfer excitation energy effectively.

[0144] Therefore, from the triplet excitation energy level of the excited complex, the compound that forms the excited complex A higher triplet excitation energy level is preferable. That is, organic compound 121_1 And the triplet excitation energy level of organic compound 121_2 is, with organic compound 121_1 and The triplet excitation energy level of the excited complex formed with compound 121_2 is higher than that of compound 121_2. This is preferable. Furthermore, the triplet excitation energy level of the excited complex is the triplet excitation of guest material 122. It is preferable that the excitation energy level is higher than the electromotive force level. Furthermore, the excited complex exhibits thermally activated delayed fluorescence at room temperature. When this is shown, the phosphorescence emission energies of organic compound 121_1 and organic compound 121_2 are, Thermally activated delayed firefly of an excited complex formed by organic compound 121_1 and organic compound 121_2 It is preferable that the emission energy is higher than that of light. Also, the thermally activated delayed fluorescence of the excited complex The light energy is preferably higher than the phosphorescence emission energy of the guest material 122.

[0145] As described above, in a light-emitting element according to one aspect of the present invention, the host material 12 in the light-emitting layer The singlet excitation energy levels and triplet excitation energy levels of 1 and guest material 122 are raised. By using the described configuration, it is possible to provide a light-emitting element with high luminescence efficiency.

[0146] <3. Components of a light-emitting element> Next, the details of the other components of the light-emitting element 150 shown in Figure 1(A) will be described below. do.

[0147] ≪3-1. A pair of electrodes≫ Electrodes 101 and 102 have the function of injecting holes and electrons into the light-emitting layer 113. The poles 101 and 102 are made of metals, alloys, conductive compounds, and mixtures or laminates thereof. It can be formed using materials such as aluminum (Al). Other materials include silver (Ag), tungsten (W), chromium (Cr), molybdenum (Mo), and copper. Transition metals such as copper (Cu), titanium (Ti), lithium (Li), sodium (Na), and cereals Alkali metals such as cium (Cs), calcium (Ca), magnesium (Mg), etc. Group 2 metals can be used. As transition metals, rare earth elements such as ytterbium (Yb) can be used. Metals may be used. As for alloys, alloys containing the above-mentioned metals can be used, for example Examples include MgAg and AlLi. Conductive compounds include indium oxide-sulfide oxide. Examples include metal oxides such as indium tin oxide. Conductive compounds Inorganic carbon-based materials such as graphene may also be used. As mentioned above, these materials Even if one or both of electrodes 101 and 102 are formed by stacking multiple of these, good.

[0148] Furthermore, the light emitted from the light-emitting layer 113 is emitted from one or both of the electrodes 101 and 102. It is extracted through. Therefore, at least one of electrode 101 and electrode 102 is visible. It transmits light. When using a material with low light transmittance, such as metal or alloy, for the electrode that extracts light... In this case, an electrode 1 with a thickness sufficient to transmit visible light (for example, 1 nm to 10 nm thick) is used. One or both of 01 and electrode 102 may be formed.

[0149] ≪3-2. Hole Injection Layer≫ The hole injection layer 111 reduces the hole injection barrier from the electrode 101, thereby enabling hole injection. It has a function that promotes this, for example, transition metal oxides, phthalocyanine derivatives, or aromatic compounds. Formed by mine, etc. Transition metal oxides include molybdenum oxide and vanadium oxide. Examples include oxides, ruthenium oxide, tungsten oxide, and manganese oxide. Examples of tarocyanine derivatives include phthalocyanines and metallurgical phthalocyanines. Examples of aromatic amines include benzidine derivatives and phenylenediamine derivatives. High molecular weight compounds such as polythiophene and polyaniline can also be used, for example, self-doping Poly(ethylenedioxythiophene) / poly(styrene) A prime example is rufonic acid.

[0150] As the hole injection layer 111, a hole transport material and a material that exhibits electron-accepting properties in relation to it are combined. A layer containing composite material can also be used. Alternatively, a layer containing an electron-accepting material and a positive A lamination of layers containing pore-transporting material may also be used. Between these materials, a steady state or electrical current may be maintained. Charge transfer is possible in the presence of an electron barrier. Examples of materials exhibiting electron-accepting properties include Kinojimeta. Organic acceptors such as chloranil derivatives and hexaazatriphenylene derivatives We can list the following: Specifically, 7,7,8,8-tetracyano-2,3,5,6- Tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, 2,3,6,7, 10,11-Hexacyano-1,4,5,8,9,12-Hexazatriphenylene (abbreviated) These are compounds that have electron-withdrawing groups (halogen groups or cyano groups), such as HAT-CN. Furthermore, transition metal oxides, such as oxides of Group 4 to Group 8 metals, can be used. Specifically, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, acid These include tungsten oxide, manganese oxide, and rhenium oxide. Among these, molybdenum oxide is particularly toxic to the atmosphere. Among them, it is preferable because it is stable, has low hygroscopicity, and is easy to handle.

[0151] As a hole-transporting material, a material with higher hole transport capabilities than electron transport can be used, ×10 -6 cm 2 It is preferable that the material has a hole mobility of / Vs or greater. Specifically This uses aromatic amines, carbazole derivatives, aromatic hydrocarbons, stilbene derivatives, etc. This is possible. Furthermore, the hole-transporting material may be a polymer compound.

[0152] ≪3-3. Hole Transport Layer≫ The hole transport layer 112 is a layer containing a hole transportable material, and is an example of the material used for the hole injection layer 111. The materials shown can be used. The hole transport layer 112 is injected into the hole injection layer 111. Because it has the function of transporting holes to the light-emitting layer 113, the HOMO level of the hole injection layer 111 is the same as It is preferable to have the same or close HOMO level.

[0153] ≪3-4.Electron transport layer≫ The electron transport layer 115 receives electrons injected from the electrode 102 via the electron injection layer 116 into the light-emitting layer It has the function of transporting to 113. As an electron transport material, it has higher electron transport properties than holes. It can use materials, 1 × 10 -6 cm 2 Materials having electron mobility of / Vs or greater It is preferable to have them. Specifically, quinoline ligands, benzoquinoline ligands, oxazole Metal complexes having a ligand or thiazole ligand, oxadiazole derivatives, and tri Examples include azole derivatives, phenanthroline derivatives, pyridine derivatives, and bipyridine derivatives. It can be done.

[0154] ≪3-5.Electron injection layer≫ The electron injection layer 116 promotes electron injection by reducing the electron injection barrier from the electrode 102. It has the function of being, for example, Group 1 metals, Group 2 metals, or their oxides and halides. Carbonates and the like can be used. In addition, the electron transport material shown above and the electron transport material therefor Composite materials exhibiting electron-donating properties can also be used. Examples of electron-donating materials include: Examples include Group 1 metals, Group 2 metals, or oxides thereof.

[0155] Furthermore, the hole injection layer 111, hole transport layer 112, electron transport layer 115, and electron injection layer described above The layer 116 is produced by vapor deposition (including vacuum deposition), inkjet, coating, and It can be formed by methods such as labia printing.

[0156] Furthermore, the hole injection layer 111, the hole transport layer 112, the light-emitting layer 113, the electron transport layer 115, and In addition to the materials mentioned above, the electron injection layer 116 may contain inorganic compounds or polymer compounds (oligomers). (Dendrimers, polymers, etc.) may also be used.

[0157] ≪3-6. Circuit Board≫ Furthermore, the light-emitting element 150 can be fabricated on a substrate made of glass, plastic, or the like. Regarding the order in which the components are fabricated on the substrate, whether the electrodes are stacked from electrode 101 to electrode 102, They can also be stacked in order.

[0158] The substrate on which the light-emitting element 150 can be formed may be, for example, glass, quartz, or plastic. A flexible substrate can be used. A flexible substrate is a flexible substrate that can be bent. A flexible substrate is a substrate that can be modified, such as polycarbonate or polya Examples include plastic substrates made of relates. Also, films and inorganic vapor-deposited films. The following can also be used. Furthermore, in the manufacturing process of the light-emitting element and optical element, the support and Anything else that functions in this way is also acceptable. Alternatively, a light-emitting element and optics. Any device that has a function to protect the element will suffice.

[0159] For example, the light-emitting element 150 can be formed using various substrates. The types of substrates are: It is not limited to a specific type. One example of such a substrate is a semiconductor substrate (for example, a single-layer semiconductor substrate). Crystal substrate or silicon substrate), SOI substrate, glass substrate, quartz substrate, plastic substrate, gold Substrates, stainless steel substrates, substrates with stainless steel foil, tungsten Tungsten substrate, substrate having tungsten foil, flexible substrate, laminated film, fiber Examples include paper or substrate films containing a material of a certain type. An example of a glass substrate is barium. Examples include borosilicate glass, aluminoborosilicate glass, or soda-lime glass. Examples of flexible substrates, laminated films, and base films include the following: For example, polyethylene terephthalate (PET), polyethylene naphthalate (P EN), polyethersulfone (PES), polytetrafluoroethylene (PTFE) There are plastics such as those mentioned above. Alternatively, as an example, there are resins such as acrylic. Alternatively, as an example, polypropylene, polyester, polyvinyl fluoride, or poly Examples include polyvinyl chloride. Alternatively, as an example, polyamide, polyimide, aramid, etc. Examples include porcelain, inorganic vapor-deposited films, or paper products.

[0160] Alternatively, a flexible substrate may be used as the substrate, and the light-emitting element may be formed directly on the flexible substrate. Alternatively, a release layer may be provided between the substrate and the light-emitting element. The release layer is provided on top of the light-emitting element. After partially or completely completing the child component, it is separated from the circuit board and used for transferring it to another circuit board. This allows for the transfer of light-emitting elements to substrates with poor heat resistance or flexible substrates. Oh, the aforementioned delamination layer has, for example, a laminated inorganic film structure of a tungsten film and a silicon oxide film. Configurations such as the one shown, or a configuration in which a resin film such as polyimide is formed on the substrate, can be used.

[0161] In other words, a light-emitting element is formed using one substrate, and then the light-emitting element is transferred to another substrate. The light-emitting element may be placed on a different substrate. An example of a substrate on which the light-emitting element is placed is the above In addition to the substrates mentioned above, there are also cellophane substrates, stone substrates, wood substrates, and cloth substrates (natural fibers (silk, cotton, Hemp), synthetic fibers (nylon, polyurethane, polyester) or regenerated fibers (acetate) (including t, cupro, rayon, recycled polyester, etc.), leather substrate, or rubber substrate. These substrates can be used to create light-emitting elements that are less prone to breakage and have high heat resistance. This can be a child, a lightweight light-emitting element, or a thinned light-emitting element.

[0162] Furthermore, a field-effect transistor (FET), for example, is formed on the aforementioned substrate, and the FET and The light-emitting element 150 may be fabricated on electrically connected electrodes. This allows the FET to This allows us to create an active-matrix type display device that controls the driving of the light-emitting element 150.

[0163] In this embodiment, one aspect of the present invention has been described. Or, other embodiments may be described. In this context, one aspect of the present invention will be described. However, this aspect of the present invention is not limited to these. It is not done. For example, in one aspect of the present invention, in a host material, singlet excitation energy level An example where the difference between the position and the triplet excitation energy level is greater than 0 eV and less than or equal to 0.2 eV. As shown, the present invention is not limited thereto. Depending on the circumstances, Therefore, in one aspect of the present invention, for example, in a host material, the singlet excitation energy level and The difference from the triplet excitation energy level does not necessarily have to be greater than 0 eV and less than or equal to 0.2 eV. For example, in one aspect of the present invention, a host material exhibits thermally activated delayed fluorescence at room temperature. While an example of a substance has been given, one aspect of the present invention is not limited thereto. Alternatively, depending on the circumstances, in one aspect of the present invention, for example, the host material is thermally active at room temperature. It may contain substances other than those exhibiting delayed fluorescence. Or, in some cases, or Depending on the circumstances, in one aspect of the present invention, for example, the host material exhibits thermally activated delayed fluorescence at room temperature. It is not necessary to have the indicated substance. Or, for example, in one aspect of the present invention, the host material The triplet excitation energy level is higher than the triplet excitation energy level of the guest material. While examples have been provided, the present invention is not limited thereto. In some cases, or in certain situations, Accordingly, in one aspect of the present invention, for example, the triplet excitation energy level of the host material is It does not need to be higher than the triplet excitation energy level of the material.

[0164] The configuration shown in this embodiment can be used in appropriate combination with other embodiments. Cut.

[0165] (Embodiment 2) In this embodiment, the light-emitting element has a configuration different from that shown in Embodiment 1, and The light-emitting mechanism of the light-emitting element will be explained below using Figures 5(A) and 5(B).

[0166] <Example of light-emitting element configuration> Figure 5(A) is a schematic cross-sectional view of the light-emitting element 450.

[0167] The light-emitting element 450 shown in Figure 5(A) has a pair of electrodes (electrode 401 and electrode 402) between them. , multiple light-emitting units (in Figure 5(A), light-emitting unit 441 and light-emitting unit 4 42) has. One light-emitting unit has a configuration similar to the EL layer 100 shown in Figure 1. In other words, the light-emitting element 150 shown in Figure 1 has one light-emitting unit, and the light-emitting element 450 It has multiple light-emitting units. In the light-emitting element 450, the electrode 401 is the anode and Assuming that electrode 402 functions as the cathode, the following explanation will be given, but the light-emitting element 450 The configuration can also be reversed.

[0168] Furthermore, in the light-emitting element 450 shown in Figure 5(A), the light-emitting unit 441 and the light-emitting unit 442 is stacked with 441 and 442, and between light-emitting unit 441 and light-emitting unit 442 there is an electric current A bio-layer 445 is provided. Note that the light-emitting units 441 and 442 have the same configuration. However, a different configuration is also acceptable. For example, the light-emitting unit 441 may use the EL layer 100 shown in Figure 1. It is preferable to use a light-emitting layer having a phosphorescent material as the light-emitting material in the light-emitting unit 442. .

[0169] In other words, the light-emitting element 450 has a light-emitting layer 443 and a light-emitting layer 444. In addition to the light-emitting layer 443, the optical unit 441 includes a hole injection layer 411, a hole transport layer 412, and an electron It has a transport layer 413 and an electron injection layer 414. The light-emitting unit 442 has a light-emitting layer 4 In addition to 44, there are hole injection layer 415, hole transport layer 416, electron transport layer 417, and electron injection layer It has 418.

[0170] The charge generation layer 445 contains a composite material of an organic compound and an acceptor substance. The composite material includes a composite material that can be used in the hole injection layer 111 shown in Embodiment 1. You can use them. As for organic compounds, aromatic amine compounds, carbazole compounds, aromatic Various compounds, including hydrocarbons and polymer compounds (oligomers, dendrimers, polymers, etc.) This can be used. As for organic compounds, a hole mobility of 1 × 10⁻⁶ is used. -6 cm 2 / It is preferable to use one with a value of Vs or higher. However, a value that has a higher hole transport rate than electron transport rate. Other substances may be used as well. A combination of organic compounds and acceptor substances. Because composite materials have excellent carrier implantation and carrier transport properties, they are suitable for low-voltage and low-current operation. This can be achieved. Note that, as with the light-emitting unit 442, the anode side of the light-emitting unit When the surface is in contact with the charge generation layer 445, the charge generation layer 445 is in contact with the holes of the light-emitting unit. Since it can also serve as an injection layer or hole transport layer, the light-emitting unit has a hole injection layer. Alternatively, a hole transport layer may not be necessary.

[0171] Furthermore, the charge generation layer 445 includes a layer containing a composite material of an organic compound and an acceptor substance, It may also be formed as a laminated structure combining layers made of other materials. A layer containing a composite material of an organic compound and an acceptor substance, and an electron-donating substance selected from among these. A layer containing one compound and a compound with high electron transport properties may be formed by combining these layers. Furthermore, a layer containing a composite material of an organic compound and an acceptor substance, and a layer containing a transparent conductive film. They may be formed by combining these elements.

[0172] Furthermore, the charge generation layer 445 can be generated by vapor deposition (including vacuum deposition), inkjet, or coating methods. It can be formed by methods such as gravure printing.

[0173] The charge generation layer 445, sandwiched between the light-emitting unit 441 and the light-emitting unit 442, is an electrode. When a voltage is applied to 401 and electrode 402, electrons are injected into one light-emitting unit, and the other Any method that injects holes into the light-emitting unit is acceptable. For example, in Figure 5(A), the electrodes When a voltage is applied such that the potential of electrode 401 is higher than the potential of electrode 402, the charge generation The bio-layer 445 injects electrons into the light-emitting unit 441 and holes into the light-emitting unit 442. ru.

[0174] Furthermore, Figure 5(A) illustrates a light-emitting element having two light-emitting units. However, the same configuration can also be applied to light-emitting elements that stack three or more light-emitting units. This is possible. As shown in the light-emitting element 450, multiple light-emitting units are charged between a pair of electrodes. By separating and arranging the elements in a generation layer, high-brightness light emission is possible while maintaining a low current density. Furthermore, it becomes possible to realize light-emitting elements with an even longer lifespan. In addition, it becomes possible to realize light-emitting elements with low power consumption. can.

[0175] Furthermore, the configuration of the EL layer 100 is suitable for at least one of the multiple units. By using this technology, it is possible to provide a light-emitting element with high luminescence efficiency.

[0176] Furthermore, the light-emitting layer 443 has a host material 421 and a guest material 422. The light layer 444 has a host material 431 and a guest material 432. Also, the host material 4 21 comprises organic compound 421_1 and organic compound 421_2. Also, the host material Material 431 comprises organic compound 431_1 and organic compound 431_2.

[0177] Furthermore, in this embodiment, the light-emitting layer 443 is the same as the light-emitting layer 113 shown in Figure 2(A). The configuration is as follows: The host material 421 (organic compound 421_ of the light-emitting layer 443 1 and organic compound 421_2), and guest material 422 are host materials of the light-emitting layer 113 Material 121 (organic compound 121_1 and organic compound 121_2), and guest material 122 These correspond to the respective. In addition, the guest material 432 of the light-emitting layer 444 is a phosphorescent material. The following will be explained. Note that the electrodes 401, 402, hole injection layers 411, 415, and hole transport Layers 412, 416, electron transport layers 413, 417, and electron injection layers 414, 418 are implemented. As shown in form 1, electrode 101, electrode 102, hole injection layer 111, hole transport layer 112, electron These correspond to the transport layer 115 and the electron injection layer 116, respectively. Therefore, in this embodiment... In this regard, a detailed explanation will be omitted.

[0178] <Light emission mechanism of light-emitting layer 443> The light-emitting mechanism of the light-emitting layer 443 is the same as that of the light-emitting layer 113 shown in Figure 2(B). be.

[0179] <Light emission mechanism of light-emitting layer 444> Next, the light-emitting mechanism of the light-emitting layer 444 will be explained below.

[0180] The organic compound 431_1 and organic compound 431_2 in the light-emitting layer 444 form an excited complex. Here, organic compound 431_1 is used as the host material, and organic compound 431_ We will explain using point 2 as an assisting element.

[0181] Organic compound 431_1 and organic compound 431_ that form the excitation complex in the light-emitting layer 444 The combination with 2 can be any combination that can form an excited complex, but on the other hand It is preferable that one material has hole transport properties and the other has electron transport properties. It seems so. Furthermore, the combination of organic compound 431_1 and organic compound 431_2 is the light-emitting layer In 443, the organic compound 421_1 and organic compound 421_2 form an excited complex. The same configuration as the combination may also be used.

[0182] Organic compound 431_1, organic compound 431_2, and guest material in the light-emitting layer 444 The correlation of energy levels with 432 is shown in Figure 5(B). Note that the notation in Figure 5(B) and The symbols are as follows: ·Host(431_1): Host material (organic compound 431_1) • Assist (431_2): Assist material (organic compound 431_2) • Guest (432): Guest material 432 (phosphorescent material) ·S PH : The lowest level of the singlet excited state of the host material (organic compound 431_1) ·T PH : The lowest level of the triplet excited state of the host material (organic compound 431_1) ·T PG : The lowest level of the triplet excited state of guest material 432 (phosphorescent material) ·S PE : The lowest level of the singlet excited state of the excited complex ·T PE: The lowest level of the triplet excited state of the excited complex

[0183] Singlet excited complex formed by organic compound 431_1 and organic compound 431_2 The lowest level of the excited state (S PE ) and the lowest level of the triplet excited state of the excited complex (T PE ) will be adjacent to each other (see Figure 5(B)E7).

[0184] And the S of the excited complex PE and T PE The energy of both is transferred to guest material 432 (phosphor material) The lowest level (T) of the triplet excited state of the material PG Move it to (Figure 5(B)) to obtain light emission (Figure 5(B) (See E8).

[0185] Furthermore, the processes E7 and E8 described above are referred to as ExTET(Excip) in this specification, etc. It is sometimes referred to as lex-Triplet Energy Transfer.

[0186] Furthermore, organic compound 431_1 and organic compound 431_2 have holes in one and electrons in the other. It receives a child, and when they come into close proximity, they quickly form an excited complex. Alternatively, one of them When it enters an excited state, it quickly incorporates the other substance to form an excited complex. Therefore, Most of the excitons in the luminescent layer 444 exist as excited complexes. Excited complexes are organically formed. The band gap is smaller than that of both compound 431_1 and organic compound 431_2. Therefore, the formation of an excitation complex can lower the driving voltage of the light-emitting element.

[0187] By configuring the light-emitting layer 444 as described above, the guest material 432 (phosphorescent material) of the light-emitting layer 444 This makes it possible to efficiently obtain light emission from ).

[0188] Furthermore, the emission from the light-emitting layer 443 has a shorter wavelength peak than the emission from the light-emitting layer 444. It is preferable to have a configuration that has a luminescent element. The child tends to experience rapid brightness degradation. Therefore, by using fluorescence emission for short-wavelength emission, This makes it possible to provide a light-emitting element with minimal brightness degradation.

[0189] Furthermore, by obtaining light of different emission wavelengths from the light-emitting layer 443 and the light-emitting layer 444, multicolor It can be used as a light-emitting element. In this case, the emission spectrum will have different emission peaks. Since the emitted light is a composite of light, the emission spectrum will have at least two maxima. .

[0190] Furthermore, the above configuration is also suitable for obtaining white light emission. (Light-emitting layer 443 and light-emitting layer 444) By making the light and the light complementary to each other, white light emission can be obtained.

[0191] Furthermore, one or both of the light-emitting layers 443 and 444 have multiple emission wavelengths with different emission wavelengths. By using multiple luminescent materials, it is possible to produce highly color-rendering colors consisting of the three primary colors or four or more luminescent colors. White light emission can also be obtained. In this case, either the light-emitting layer 443 or the light-emitting layer 444. Alternatively, both can be further divided into layers, and each divided layer can contain a different light-emitting material. You can do that too.

[0192] Next, the materials that can be used for the light-emitting layer 443 and the light-emitting layer 444 will be described below. ru.

[0193] <Materials that can be used for the light-emitting layer 443> Materials that can be used for the light-emitting layer 443 include the light-emitting layer 113 shown in the previous embodiment. You can use materials that can be used for that purpose.

[0194] <Materials that can be used for the light-emitting layer 444> In the light-emitting layer 444, the host material (organic compound 431_1 and organic compound 431_2) It is the most abundant by weight, and guest material 432 (phosphorescent material) is the host material (organic compound It is dispersed in 431_1 and organic compound 431_2).

[0195] Organic compound 431_1 (host material) includes zinc and aluminum-based metal complexes, Oxadiazole derivatives, triazole derivatives, benzimidazole derivatives, quinoxali Dibenzoquinoxaline derivatives, dibenzothiophene derivatives, dibenzofuran derivatives Conductors, pyrimidine derivatives, triazine derivatives, pyridine derivatives, bipyridine derivatives, fer Examples include nanthroline derivatives. Other examples include aromatic amines and carbazole derivatives. Examples include conductors.

[0196] As organic compound 431_2 (assist material), an excited complex is formed with organic compound 431_1. This is a combination that can be formed. In this case, the emission peak of the excited complex is the triplet ML of the phosphorescent material. Absorption of CT (Metal to Ligand Charge Transfer) transitions More specifically, organic compound 431_1 overlaps with the absorption band on the longest wavelength side. It is preferable to select compound 431_2 and guest material 432 (phosphorescent material). This makes it possible to create a light-emitting element with dramatically improved luminous efficiency. However, phosphorescent material When thermally activated delayed fluorescence materials are used instead, the absorption band on the longest wavelength side is singlet. It is preferable that it be an absorption band.

[0197] Guest material 432 (phosphorescent material) can be iridium, rhodium, or platinum-based organic materials. Examples include metal complexes, or metal complexes in particular, organoiridium complexes, such as iridium Orthometallic complexes are preferred. 4H-triazole is a suitable ligand for orthometallation. Ligands, 1H-triazole ligands, imidazole ligands, pyridine ligands, pyrimidines Examples include ligands, pyrazine ligands, or isoquinoline ligands. Examples include platinum complexes having porphyrin ligands.

[0198] The guest material 432 included in the light-emitting layer 444 converts triplet excitation energy into light emission. Any material that can convert the triplet excitation energy into light emission is acceptable. Examples of materials that can convert the triplet excitation energy into light emission include: In addition to phosphorescent materials, thermally activated delayed fluorescence materials can also be mentioned. Therefore, the term "phosphorescent material" is used. Regarding this part, it may be interpreted as thermally activated delayed fluorescence material. Optical materials are materials that can upcycle a triplet excited state to a singlet excited state using a small amount of thermal energy. It allows for reverse intersystem crossing and efficiently exhibits luminescence (fluorescence) from the singlet excited state. It refers to the materials. Also, the conditions under which thermally activated delayed fluorescence can be efficiently obtained include triplet excitation. Preferably, the energy difference between the electromotive force level and the singlet excitation energy level exceeds 0 eV. The voltage is 0.2 eV or less, and more preferably greater than 0 eV and 0.1 eV or less. It can be done.

[0199] Furthermore, the emission colors of the light-emitting material contained in the light-emitting layer 443 and the light-emitting material contained in the light-emitting layer 444 There are no limitations; they can be the same or different. The light emitted from each is mixed and released outside the element. Since it is extracted, for example, if the light-emitting colors of both materials are complementary to each other, the light-emitting element will be white. It can emit colored light. Considering the reliability of the light-emitting element, the light-emitting layer 443 is included. The emission peak wavelength of the light-emitting material (guest material 422) is the light-emitting material contained in the light-emitting layer 444 ( It is preferable that the wavelength is shorter than the emission peak wavelength of the guest material 432).

[0200] Furthermore, the light-emitting layers 443 and 444 are produced by vapor deposition (including vacuum deposition) and inkjet. It can be formed by methods such as the printing method, coating method, and gravure printing.

[0201] The configuration shown in this embodiment may be used in appropriate combination with the configurations shown in other embodiments. It is possible to be there.

[0202] (Embodiment 3) In this embodiment, a configuration different from the configurations shown in Embodiments 1 and 2 is generated. The optical element will be explained below using Figures 6(A) and 6(B).

[0203] <Example of light-emitting element configuration> Figure 6(A) is a schematic cross-sectional view illustrating a light-emitting element 452 according to one embodiment of the present invention.

[0204] The light-emitting element 452 has multiple light-emitting units (Figure 6) between the electrode 401 and the electrode 402. In A), there are light-emitting units 446 and 447). The knit has a similar structure to the EL layer 100 shown in Figure 1. In other words, the light-emitting element shown in Figure 1 Child 150 has one light-emitting unit, and light-emitting element 452 has multiple light-emitting units. In this embodiment, electrode 401 is the anode and electrode 402 is the cathode, and the following explanation is provided. To clarify, the configuration of the light-emitting element 452 can also be reversed.

[0205] Furthermore, in the light-emitting element 452 shown in Figure 6(A), the light-emitting unit 446 and the light-emitting unit 447 and are stacked, and between the light-emitting unit 446 and the light-emitting unit 447 there is an electric current A bio-layer 445 is provided. Note that the light-emitting units 446 and 447 have the same configuration. However, a different configuration is also acceptable. For example, the light-emitting unit 446 may have a fluorescent material as the light-emitting material. It is preferable to use a light-emitting layer and to use the EL layer 100 shown in Figure 1 for the light-emitting unit 447.

[0206] In other words, the light-emitting element 452 has a light-emitting layer 448 and a light-emitting layer 449. In addition to the light-emitting layer 448, the optical unit 446 includes a hole injection layer 411, a hole transport layer 412, and an electron It has a transport layer 413 and an electron injection layer 414. The light-emitting unit 447 has a light-emitting layer 4 In addition to 49, there are hole injection layer 415, hole transport layer 416, electron transport layer 417, and electron injection layer It has 418.

[0207] Furthermore, Figure 6(A) illustrates a light-emitting element having two light-emitting units. However, the same principle can also be applied to light-emitting devices that have three or more light-emitting units stacked on top of each other. As shown in the light-emitting element 452, multiple light-emitting units are placed between a pair of electrodes in a charge generation layer. By partitioning and arranging the elements, high-brightness light emission is possible while maintaining a low current density, and further This enables the creation of long-life components and low-power display devices.

[0208] Furthermore, the configuration of the EL layer 100 is suitable for at least one of the multiple units. By using this technology, it is possible to provide a light-emitting element with high luminescence efficiency.

[0209] Furthermore, the light-emitting layer 448 has a host material 461 and a guest material 462. The light layer 449 has a host material 471 and a guest material 472. 71 comprises organic compound 471_1 and organic compound 471_2.

[0210] Furthermore, in this embodiment, the light-emitting layer 449 is the same as the light-emitting layer 113 shown in Figure 2(A). The configuration is as follows: The host material 471 (organic compound 471_ of the light-emitting layer 449 1 and organic compound 471_2), and guest material 472 are host materials of the light-emitting layer 113 Material 121 (organic compound 121_1 and organic compound 121_2), and guest material 122 These correspond to the respective. In addition, the guest material 462 of the light-emitting layer 448 is a fluorescent material. The following explains this.

[0211] <Light-emitting mechanism of light-emitting layer 448> First, the light-emitting mechanism of the light-emitting layer 448 will be explained below.

[0212] In the light-emitting layer 448, excitons are generated by carrier recombination. Guest material 462 In comparison, host material 461 is abundant, so by generating excitons, host material 4 61 excited states are formed. Singlet excitons and triplet excitons are produced by carrier recombination. The ratio of excitons (hereinafter referred to as the exciton generation probability) is approximately 1:3.

[0213] An exciton is a carrier (electron and hole) pair. An exciton has energy. Therefore, the material from which excitons are generated enters an excited state.

[0214] First, consider the case where the T1 level of host material 461 is higher than the T1 level of guest material 462. The following explains this.

[0215] The triplet excitation energy of host material 461 is from the T1 level of host material 461 to the guest Energy is transferred (triplet energy transfer) to the T1 level of material 462. However, Since guest material 462 is a fluorescent material, the triplet excitation energy imparts light emission in the visible light region. Therefore, the triplet excitation energy of the host material 461 cannot be used as light emission. However, this is difficult. Therefore, the T1 level of the host material 461 is higher than the T1 level of the guest material 462. In some cases, it is difficult to utilize more than approximately 25% of the injected carrier for luminescence. It's nice.

[0216] Next, the host material 461 and guest material 462 in the light-emitting layer 448 of one aspect of the present invention The correlation of energy levels is shown in Figure 6(B). Note the notation and symbols in Figure 6(B). The following applies: • Host: Host material 461 • Guest: Guest material 462 (fluorescent material) ·S FH : The lowest level (S1 level) of the singlet excited state of host material 461 ·T FH : The lowest level (T1 level) of the triplet excited state of host material 461. ·S FG : The lowest level (S1 level) of the singlet excited state of guest material 462 (fluorescent material) ·T FG : The lowest level (T1 level) of the triplet excited state of guest material 462 (fluorescent material)

[0217] As shown in Figure 6(B), the T1 level of guest material 462 (in Figure 6(B), T FG ) is the T1 level of the host material 461 (in Figure 6(B), T FH ) is a higher configuration .

[0218] Furthermore, as shown in Figure 6(B), triplet-triplet annihilation (TTA: Triplet-Tr Triplet excitation (see Figure 6(B)E9) is performed by iplet annihilation. When the children collide with each other, some of them reach the lowest singlet excited state of the host material 461. Level (S FH It is converted into a singlet exciton having the energy of ). The doublet excitation energy is the lowest level (S) of the singlet excited state of the host material 461. FH )mosquito Then, the singlet excited state of guest material 462 (fluorescent material), which has an even lower energy, is the most also a low level (S FG Energy transfer occurs (Figure 6(B)E) 10 (Reference), guest materials A singlet excited state is formed in material 462 (fluorescent material). As a result, guest material 462 emits It shines.

[0219] Furthermore, since the T1 level of the host material is lower than the T1 level of the guest material, FG Excitation Energy does not deactivate T FH Energy transfer (Figure 6(B)E) 11 (See also) TT It will be used for A.

[0220] By configuring the light-emitting layer 448 as described above, light emission from the guest material 462 of the light-emitting layer 448 is achieved. This makes it possible to obtain it efficiently.

[0221] Furthermore, by obtaining light of different emission wavelengths from the light-emitting layer 448 and the light-emitting layer 449, multicolor It can be used as a light-emitting element. In this case, the emission spectrum will have different emission peaks. Since the emitted light is a composite of light, the emission spectrum will have at least two maxima. .

[0222] Furthermore, the above configuration is also suitable for obtaining white light emission. (Light-emitting layer 448 and light-emitting layer 449) By making the light and the light complementary to each other, white light emission can be obtained.

[0223] Furthermore, one or both of the light-emitting layers 448 and 449 may have multiple emission wavelengths with different emission wavelengths. By using multiple luminescent materials, it is possible to produce highly color-rendering colors consisting of the three primary colors or four or more luminescent colors. White light emission can also be obtained. In this case, either the light-emitting layer 448 or the light-emitting layer 449 Alternatively, both can be further divided into layers, and each divided layer can contain a different light-emitting material. You can do that too.

[0224] <Light-emitting mechanism of light-emitting layer 449> The light-emitting mechanism of the light-emitting layer 449 is the same as that of the light-emitting layer 113 shown in Figure 2.

[0225] Next, the materials that can be used for the light-emitting layer 448 and the light-emitting layer 449 will be described below. ru.

[0226] <Materials that can be used for the light-emitting layer 448> In the light-emitting layer 448, the host material 461 is the most abundant by weight, followed by the guest material 462 The (fluorescent material) is dispersed in the host material 461. The S1 level of the host material 461 is The T1 level of host material 461 is higher than that of host material 462 (fluorescent material), It is preferable that the level is lower than the T1 level of material 462 (fluorescent material).

[0227] As the host material 461, anthracene derivatives or tetracene derivatives are preferred. This is because these derivatives have a high S1 level and a low T1 level. Specifically, 9-Fe Nyl-3-[4-(10-phenyl-9-antryl)phenyl]-9H-carbazole (Abbreviation: PCzPA), 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H -Carbazole (abbreviation: PCPN), 9-[4-(10-phenyl-9-anthracenyl )phenyl]-9H-carbazole (abbreviation: CzPA), 7-[4-(10-phenyl- 9-Anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDB) CzPA), 6-[3-(9,10-diphenyl-2-anthryl)phenyl]-benzo [b]Naphtho[1,2-d]furan (abbreviation: 2mBnfPPA), 9-phenyl-10- {4-(9-phenyl-9H-fluoren-9-yl)-biphenyl-4'-yl} Examples include nitrates (abbreviated as FLPPA). Alternatively, 5,12-diphenyl nitrates... Examples include transene and 5,12-bis(biphenyl-2-yl)tetracene.

[0228] Guest material 462 (fluorescent material) includes pyrene derivatives, anthracene derivatives, and truffles. phenylene derivatives, fluorene derivatives, carbazole derivatives, dibenzothiophene derivatives, Dibenzofuran derivatives, dibenzoquinoxaline derivatives, quinoxaline derivatives, pyridine derivatives Examples include conductors, pyrimidine derivatives, phenanthrene derivatives, and naphthalene derivatives. Pyrene derivatives are particularly 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) Examples include rn).

[0229] <Materials that can be used for the light-emitting layer 449> Materials that can be used for the light-emitting layer 449 include the light-emitting layer 113 shown in the previous embodiment. You can use materials that can be used for that purpose.

[0230] Furthermore, the emission colors of the light-emitting material contained in the light-emitting layer 448 and the light-emitting material contained in the light-emitting layer 449 There are no limitations; they can be the same or different. The light emitted from each is mixed and released outside the element. Since it is extracted, for example, if the light-emitting colors of both materials are complementary to each other, the light-emitting element will be white. It can emit colored light. Considering the reliability of the light-emitting element, it is included in the light-emitting layer 448. The emission peak wavelength of the luminescent material (guest material 462) is the same as that of the luminescent material (guest material 462) contained in the emission layer 449. It is preferable that the wavelength is shorter than the emission peak wavelength of the stock material (472).

[0231] Furthermore, the light-emitting layers 448 and 449 are produced by vapor deposition (including vacuum deposition) and inkjet. It can be formed by methods such as the printing method, coating method, and gravure printing.

[0232] The above configuration may be appropriately combined with other embodiments or other configurations within this embodiment. This is possible.

[0233] (Embodiment 4) In this embodiment, a display device having a light-emitting element according to one aspect of the present invention is shown in Figure 7(A). (B) will be used for the explanation.

[0234] Figure 7(A) is a block diagram illustrating a display device according to one embodiment of the present invention, and Figure 7( B) is a circuit diagram illustrating a pixel circuit in a display device according to one aspect of the present invention.

[0235] <Explanation regarding display devices> The display device shown in Figure 7(A) has a region having pixels of the display element (hereinafter referred to as the pixel portion 802). (u) and a circuit section ( ) located outside the pixel section 802 and having a circuit for driving the pixels. Below, referred to as the drive circuit section 804, and a circuit that has a function to protect the element (hereinafter referred to as the protection circuit 806) It has a terminal section 807 and a protection circuit 806. That's good too.

[0236] Part or all of the drive circuit section 804 is formed on the same substrate as the pixel section 802. This is desirable. This allows for a reduction in the number of components and terminals. Drive circuit section 804 If part or all of it is not formed on the same substrate as the pixel section 802, the drive cycle Part or all of road section 804 is COG (Chip On Glass) or TAB (T This can be implemented using APE (Automated Bonding).

[0237] The pixel section 802 is arranged in X rows (where X is a natural number greater than or equal to 2) and Y columns (where Y is a natural number greater than or equal to 2). It has a circuit for driving multiple display elements (hereinafter referred to as the pixel circuit 801), and the drive cycle The path section 804 is a circuit that outputs a signal (scan signal) for selecting pixels (hereinafter referred to as the scan line drive circuit). 804a) is used to supply signals (data signals) for driving the pixel display elements. It has a drive circuit such as the signal line drive circuit 804b.

[0238] The scan line driving circuit 804a includes a shift register, etc. The scan line driving circuit 804a is A signal to drive the shift register is input via terminal 807, and the signal is output. For example, the scan line drive circuit 804a receives a start pulse signal, a clock signal, etc. The scan line drive circuit 804a outputs a pulse signal. The scanning signal is supplied to the wiring (and It has the function of controlling the potential of the scan lines (referred to as GL_1 to GL_X). Multiple drive circuits 804a are provided, and the scan line GL_1 is driven by multiple scan line drive circuits 804a. The path to GL_X may be divided and controlled. Alternatively, the scan line drive circuit 804a may use an initialization signal. It has the function of supplying, however, the scan line drive circuit 80 4a can also supply another signal.

[0239] The signal line drive circuit 804b includes a shift register, etc. The signal line drive circuit 804b is Through terminal 807, in addition to signals for driving the shift register, the data signals are generated. A signal (image signal) is input. The signal line drive circuit 804b uses the image signal to drive the pixel circuit It has the function of generating data signals to be written to 801. In addition, the signal line drive circuit 804b The data signal is transmitted according to the pulse signal obtained by inputting the start pulse, clock signal, etc. It has the function of controlling the output of the signal. In addition, the signal line drive circuit 804b is provided with a data signal. It has the function of controlling the potential of the wiring (hereinafter referred to as data lines DL_1 to DL_Y). Alternatively, the signal line drive circuit 804b may have the function of supplying an initialization signal. However, it is not limited to this, and the signal line drive circuit 804b may also supply other signals. It is possible.

[0240] The signal line drive circuit 804b is configured using, for example, multiple analog switches. The signal line drive circuit 804b sequentially turns on multiple analog switches, The image signal can be time-divided and output as a data signal. It can also use shift registers, etc. The signal line drive circuit 804b may be constructed using this.

[0241] Each of the multiple pixel circuits 801 receives a scan signal from one of the multiple scan lines GL. A pulse signal is input via one of several data lines DL to which a data signal is supplied. A data signal is input. In addition, each of the multiple pixel circuits 801 is a scan line drive circuit 804a controls the writing and retention of data in the data signal. For example, m rows and n columns. The pixel circuit 801 of the eye is driven by a scan line drive circuit via the scan line GL_m (where m is a natural number less than or equal to X). A pulse signal is input from 804a, and the data line DL_n( A data signal is input from the signal line drive circuit 804b via n (where n is a natural number less than or equal to Y).

[0242] The protection circuit 806 shown in Figure 7(A) is, for example, a combination of the scan line drive circuit 804a and the pixel circuit 80 It is connected to the scan line GL, which is the wiring between 1. Alternatively, the protection circuit 806 is connected to the signal line drive cycle. It is connected to data line DL, which is the wiring between path 804b and pixel circuit 801. Or, protection Circuit 806 can be connected to the wiring between the scan line drive circuit 804a and the terminal section 807. Alternatively, the protection circuit 806 is connected to the wiring between the signal line drive circuit 804b and the terminal section 807. It can be connected to the terminal 807. The terminal 807 supplies power and controls to the display device from an external circuit. This refers to the section equipped with terminals for inputting signals and image signals.

[0243] The protection circuit 806, when a potential outside a certain range is applied to the wiring to which it is connected, This is a circuit that creates a conductive state between two wires.

[0244] As shown in Figure 7(A), the pixel section 802 and the drive circuit section 804 each have a protection circuit 806 By providing ESD (Electrostatic Discharge), This can improve the resistance of display devices to overcurrents generated by electrical discharge, etc. Furthermore, the configuration of the protection circuit 806 is not limited to this; for example, the scan line drive circuit 804a may also be protected Configuration with protection circuit 806 connected, or with protection circuit 806 connected to signal line drive circuit 804b It is also possible to have a configuration in which the protection circuit 806 is connected to the terminal 807. It is also possible.

[0245] Furthermore, in Figure 7(A), the scan line drive circuit 804a and the signal line drive circuit 804b This shows an example of forming the drive circuit section 804, but the configuration is not limited to this. If only the scan line drive circuit 804a is formed, and a separately prepared signal line drive circuit is formed Mounting a substrate (for example, a drive circuit substrate formed from a single-crystal semiconductor film or a polycrystalline semiconductor film) The structure is also good.

[0246] <Example of pixel circuit configuration> The multiple pixel circuits 801 shown in Figure 7(A) may be configured as shown in Figure 7(B), for example. It is possible.

[0247] The pixel circuit 801 shown in Figure 7(B) consists of transistors 852 and 854 and a capacitive element 862 It has a light-emitting element 872.

[0248] One of the source and drain electrodes of transistor 852 is supplied with a data signal. It is electrically connected to the wiring (hereinafter referred to as signal line DL_n). Furthermore, transistor 85 The gate electrode of 2 supplies electrical signals to the wiring to which the gate signal is supplied (hereinafter referred to as scan line GL_m). It connects to the target.

[0249] Transistor 852 has the function of controlling the writing of data to the data signal.

[0250] One of the pair of electrodes of the capacitive element 862 is connected to a wiring to which a potential is supplied (hereinafter referred to as the potential supply line VL). It is electrically connected to (a), and the other is the source electrode and drain of transistor 852. It is electrically connected to the other electrode.

[0251] The capacitive element 862 functions as a holding capacitor to retain the written data.

[0252] One of the source and drain electrodes of transistor 854 is connected to the potential supply line VL_a. They are electrically connected. Furthermore, the gate electrode of transistor 854 is connected to the gate electrode of transistor 852. It is electrically connected to the other of the source electrode and drain electrode.

[0253] One of the light-emitting element 872, either the anode or the cathode, is electrically connected to the potential supply line VL_b. The other end is electrically connected to the source and drain electrodes of transistor 854. It will be done.

[0254] As the light-emitting element 872, the light-emitting elements shown in Embodiments 1 to 3 may be used. It is possible.

[0255] Furthermore, a high power supply potential VDD is supplied to one of the potential supply lines VL_a and VL_b. On the other hand, a low power supply potential VSS is applied.

[0256] In a display device having the pixel circuit 801 shown in Figure 7(B), for example, the scan line shown in Figure 7(A) The drive circuit 804a sequentially selects the pixel circuit 801 for each row and turns on the transistor 852. Set the device to that state and write the data signal data.

[0257] When data is written to the pixel circuit 801, the transistor 852 turns off. It enters a holding state. Furthermore, in accordance with the potential of the written data signal, transistor 854 The amount of current flowing between the source electrode and the drain electrode is controlled, and the light-emitting element 872 controls the amount of current flowing through it. It emits light with brightness corresponding to the flow rate. By performing this sequentially for each row, an image can be displayed.

[0258] Furthermore, a light-emitting element according to one aspect of the present invention is an active element having an active element in the pixels of a display device. Trix system, or passive matrix system where the pixels of the display device do not have active elements. It can be applied to each method.

[0259] In the active matrix system, the active elements (active elements, nonlinear elements) are, In addition to transistors, various active elements (active elements, nonlinear elements) can be used. This can be done. For example, MIM (Metal Insulator Metal), or T It is also possible to use elements such as FD (Thin Film Diode). Because it involves fewer manufacturing steps, it is possible to reduce manufacturing costs or improve yield. Alternatively, these elements can improve the aperture ratio due to their small size. This allows for lower power consumption and higher brightness.

[0260] Other than the active matrix method, there are active elements (active elements, nonlinear elements) It is also possible to use a passive matrix type that does not use active elements. Because it does not use sub-elements or nonlinear elements, the manufacturing process is simpler, resulting in reduced manufacturing costs or higher yield. This can improve the performance. Alternatively, active elements (active elements, nonlinear elements) can be used. Because it does not exist, the aperture ratio can be improved, leading to lower power consumption or higher brightness. It is possible.

[0261] The configuration shown in this embodiment may be used in appropriate combination with the configurations shown in other embodiments. It is possible.

[0262] (Embodiment 5) In this embodiment, a display device having a light-emitting element according to one aspect of the present invention, and the display device Electronic devices with input devices attached will be explained using Figures 8 to 12.

[0263] <Explanation regarding the touch panel 1> In this embodiment, as an example of electronic equipment, a display device and an input device are combined. This document describes the Touch Panel 2000. It also explains the Touch Sensor as an example of an input device. This section explains when to use "sa".

[0264] Figures 8(A) and 8(B) are perspective views of the Touch Panel 2000. For clarity, the following shows typical components of the Touch Panel 2000.

[0265] The touch panel 2000 has a display device 2501 and a touch sensor 2595 (Figure 8). (See (B)). Also, the touch panel 2000 consists of circuit board 2510, circuit board 2570, and circuit board It has 2590. Note that substrates 2510, 2570, and 2590 are all acceptable. It has flexibility. However, any one of substrates 2510, 2570, and 2590. Alternatively, the entire structure may be non-flexible.

[0266] The display device 2501 has multiple pixels on the substrate 2510 and supplies signals to these pixels. It has multiple wirings 2511. The multiple wirings 2511 are located on the outer periphery of the substrate 2510. It is routed through, and a portion of it forms terminal 2519. Terminal 2519 is FPC2509 (1) is electrically connected to the signal line drive circuit 2503s. The signal from (1) can be supplied to multiple pixels.

[0267] The circuit board 2590 has a touch sensor 2595 and is electrically connected to the touch sensor 2595. It has multiple wires 2598. The multiple wires 2598 are routed around the outer periphery of the substrate 2590. A portion of it forms a terminal. This terminal is electrically connected to FPC2509(2). It continues. Note that in Figure 8(B), for clarity, the back side of substrate 2590 (substrate 2510 and The electrodes and wiring of the touch sensor 2595, which is located on the opposite side, are shown with solid lines.

[0268] For example, a capacitive touch sensor can be used as the touch sensor 2595. Capacitive capacitance methods include surface capacitance and projected capacitance.

[0269] Projected capacitance systems are classified into self-capacitance and mutual-capacitance types, mainly based on differences in their driving methods. There are several advantages. Using a mutual capacitance method is preferable because it enables simultaneous multi-point detection.

[0270] Note that the touch sensor 2595 shown in Figure 8(B) is a projected capacitive touch sensor. This configuration applies the following:

[0271] Furthermore, the touch sensor 2595 can detect the proximity or contact of an object to be detected, such as a finger. Yes, various sensors can be applied.

[0272] The projected capacitive touch sensor 2595 has electrodes 2591 and 2592. Electrode 2591 is electrically connected to one of the multiple wires 2598, and electrode 2592 is Connect electrically to any of the other wires 2598.

[0273] As shown in Figures 8(A) and 8(B), the electrode 2592 consists of multiple electrodes arranged repeatedly in one direction. It has a shape in which quadrilaterals are connected at their corners.

[0274] Electrode 2591 is quadrilateral and repeats in a direction intersecting the direction in which electrode 2592 extends. It is positioned.

[0275] Wiring 2594 is electrically connected to the two electrodes 2591 that sandwich electrode 2592. A shape that minimizes the area of ​​the intersection between electrode 2592 and wiring 2594 is preferable. This reduces the area where electrodes are not provided, thereby reducing variations in transmittance. Yes, it is possible. As a result, it reduces the variation in brightness of the light transmitted through the touch sensor 2595. It is possible.

[0276] Note that the shapes of electrodes 2591 and 2592 are not limited to these and can take on various shapes. For example, multiple electrodes 2591 are arranged so that there are as few gaps as possible, and an insulating layer is used. Multiple electrodes 2592 are provided spaced apart so that there is a region that does not overlap with electrode 2591. This configuration may also be used. In this case, between the two adjacent electrodes 2592, there is an electrical connection between them. Providing an insulated dummy electrode is preferable because it reduces the area of ​​regions with different transmittances. .

[0277] <Explanation regarding display devices> Next, the details of the display device 2501 will be explained using Figure 9(A). This corresponds to the cross-sectional view between the dashed line X1 and X2 shown in Figure 8(B).

[0278] The display device 2501 has a plurality of pixels arranged in a matrix. These pixels are display elements. It has a child and a pixel circuit that drives the display element.

[0279] The following explanation applies to the case where a light-emitting element that emits white light is applied to the display element. As explained above, the display elements are not limited to these. For example, the light emitted from each adjacent pixel You may use light-emitting elements with different emission colors to achieve a different color.

[0280] For example, substrates 2510 and 2570 have a water vapor transmission rate of 1 × 10⁻⁶ -5 g. m -2 ·day -1 The following is preferably 1 × 10 -6 g·m -2 ·day -1 The following is possible Flexible materials can be suitably used. Alternatively, the thermal expansion coefficient of the substrate 2510 and the base It is preferable to use a material whose thermal expansion coefficient is approximately equal to that of plate 2570. For example, linear expansion coefficient is 1 x 10 -3 / K or less, preferably 5 × 10 -5 / K or less, more comfortable 1×10 - 5 Materials with a temperature of / K or lower can be suitably used.

[0281] The substrate 2510 includes an insulating layer 2510a that prevents the diffusion of impurities to the light-emitting element, and a flexible Adhesive layer 2 for bonding substrate 2510b, insulating layer 2510a, and flexible substrate 2510b It is a laminate having 510c. Furthermore, the substrate 2570 is a substrate that prevents the diffusion of impurities to the light-emitting element. An insulating layer 2570a to prevent leakage, a flexible substrate 2570b, and the insulating layer 2570a and the flexible substrate The laminate has an adhesive layer 2570c that bonds 2570b together.

[0282] Examples of adhesive layers 2510c and 2570c include polyester, polyolefin, etc. Polyamide (nylon, aramid, etc.), polyimide, polycarbonate, or acrylic Ryl, urethane, and epoxy can be used. Also, resins containing siloxane bonds can be used. Materials can be used.

[0283] Furthermore, a sealing layer 2560 is provided between substrate 2510 and substrate 2570. (Sealing layer 2560) It is preferable that it has a refractive index greater than that of air. Also, as shown in Figure 9(A), the sealing layer If light is to be extracted to the 2560 side, the sealing layer 2560 can also serve as a bonding layer.

[0284] Furthermore, a sealing material may be formed on the outer periphery of the sealing layer 2560. As a result, the region surrounded by substrate 2510, substrate 2570, sealing layer 2560, and sealing material The configuration can include a light-emitting element 2550R. The sealing layer 2560 is as follows: An inert gas (such as nitrogen or argon) may be used to fill the container. Furthermore, a desiccant may be placed inside the inert gas. A structure that adsorbs moisture, etc., may also be provided. Alternatively, UV-curing resin or thermosetting resin may be used. It may be filled with fat, for example, PVC (polyvinyl chloride) resin, acrylic resin Polyimide resins, epoxy resins, silicone resins, PVB (polyvinyl butyral resins) A resin based on ) or EVA (ethylene vinyl acetate) can be used. Furthermore, as the sealing material mentioned above, it is preferable to use, for example, epoxy resin or glass frit. It seems that... Also, when using materials for sealing, it is best to use materials that do not allow moisture or oxygen to pass through. It is suitable.

[0285] Furthermore, the display device 2501 has pixels 2502R. Also, pixels 2502R are light-emitting pixels. It has a joule of 2580R.

[0286] Pixel 2502R is connected to the light-emitting element 2550R and supplies power to the light-emitting element 2550R. It has a transistor 2502t that can do this. Note that transistor 2502t is a pixel It functions as part of the circuit. Also, the light-emitting module 2580R and the light-emitting element 2550R, It has a colored layer 2567R.

[0287] The light-emitting element 2550R has a lower electrode, an upper electrode, and an EL layer between the lower electrode and the upper electrode. It has the following characteristics. As the light-emitting element 2550R, for example, the light-emitting elements shown in Embodiments 1 to 3 are suitable. It can be used.

[0288] Furthermore, a microcavity structure is employed between the lower and upper electrodes, allowing for specific wavelengths. The light intensity may be increased.

[0289] Furthermore, if the sealing layer 2560 is provided on the side from which light is extracted, the sealing layer 2560 is It is in contact with the optical element 2550R and the colored layer 2567R.

[0290] The colored layer 2567R is located in a position that overlaps with the light-emitting element 2550R. A portion 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. It is emitted to the outside of the 2580R optical module.

[0291] Furthermore, the display device 2501 is provided with a light-shielding layer 2567BM in the direction from which light is emitted. The light-shielding layer 2567BM is provided so as to surround the colored layer 2567R.

[0292] The colored layer 2567R only needs to have the function of transmitting light in a specific wavelength band. For example, a color filter that transmits light in the red wavelength range, and a color filter that transmits light in the green wavelength range. Color filters, color filters that transmit light in the blue wavelength range, color filters that transmit light in the yellow wavelength range Transparent color filters can be used. Each color filter is made from various materials. Using printing methods, inkjet methods, and etching methods using photolithography technology, It can be formed in any way.

[0293] Furthermore, the display device 2501 is provided with an insulating layer 2521. The insulating layer 2521 is made of transistors. It covers the ZISTA 2502t. The insulating layer 2521 flattens the irregularities caused by the pixel circuit. It has the function to do so. In addition, the insulating layer 2521 is given the function to suppress the diffusion of impurities. This may be done. This will prevent a decrease in the reliability of transistors such as the 2502t due to the diffusion of impurities. It can be suppressed.

[0294] Furthermore, the light-emitting element 2550R is formed above the insulating layer 2521. The lower electrode of the 550R is provided with a partition wall 2528 that overlaps the end of the lower electrode. Furthermore, a spacer that controls the distance between substrate 2510 and substrate 2570 is placed on the partition wall 2528. It may be formed.

[0295] The scan line driving circuit 2503g(1) consists of a transistor 2503t and a capacitive element 2503c It has the following characteristics. Furthermore, the drive circuit can be formed on the same substrate using the same process as the pixel circuit. ru.

[0296] Furthermore, wiring 2511 that can supply signals is provided on the circuit board 2510. Furthermore, terminal 2519 is provided on wiring 2511. Also, terminal 2519 has FP C2509(1) is electrically connected. Also, FPC2509(1) receives the video signal. It has the function of supplying clock signals, start signals, reset signals, etc. Note: FPC2 509(1) is a printed wiring board (PWB) d) may be attached.

[0297] Furthermore, transistors of various structures can be applied to the display device 2501. (Figure) In 9(A), an example is given of the case where a bottom-gate type transistor is applied. However, it is not limited to this, for example, the top-gate type transistor shown in Figure 9(B). The configuration may also be applied to the display device 2501.

[0298] Furthermore, regarding the polarity of transistors 2502t and 2503t, there are no particular limitations. There is no fixed definition, and the structure has N-channel and P-channel transistors, N-channel type A structure consisting of either a transistor or a P-channel transistor is used. It may be there. Also, the semiconductor film crystal used in transistors 2502t and 2503t There are no particular limitations regarding properties. For example, amorphous semiconductor films and crystalline semiconductor films can be used. Yes, it is possible. Also, as semiconductor materials, Group 13 semiconductors (for example, semiconductors containing gallium) are available. ), Group 14 semiconductors (for example, semiconductors containing silicon), compound semiconductors (oxide semiconductors) (including), organic semiconductors, etc. can be used. Transistor 2502t and transistor In either or both of 2503t, the energy gap is 2 eV or more, preferably By using an oxide semiconductor with a transient of 2.5 eV or higher, and more preferably 3 eV or higher, This is preferable because it can reduce the off-current of the sta. The oxide semiconductor in question is In -Ga oxide, In-M-Zn oxide (where M is Al, gallium (Ga), yttrium ( Y), zirconium (Zr), lanthanum (La), cerium (Ce), tin (Sn), ha Examples include humium (Hf) or neodymium (Nd).

[0299] <Explanation regarding touch sensors> Next, we will explain the details of the touch sensor 2595 using Figure 9(C). This corresponds to the cross-sectional view between the dashed line X3 and X4 shown in Figure 8(B).

[0300] The touch sensor 2595 has electrodes 2591 and electrodes arranged in a staggered pattern on the substrate 2590. 2592, an insulating layer 2593 covering electrodes 2591 and 2592, and adjacent electrodes 25 It has wiring 2594 that electrically connects 91.

[0301] Electrodes 2591 and 2592 are formed using a light-transmitting conductive material. Conductive materials having this property include indium oxide, indium tin oxide, and indium zinc oxide. Conductive oxides such as zinc oxide, zinc oxide, and zinc oxide with added gallium can be used. Furthermore, a film containing graphene can also be used. A film containing graphene is, for example, a film-like structure. A film containing graphene oxide formed on the surface can be reduced to form a new film. Methods such as applying heat can be cited.

[0302] For example, a light-transmitting conductive material is deposited on a substrate 2590 by sputtering. Afterward, unwanted parts are removed using various pattern formation techniques such as photolithography. Electrodes 2591 and 2592 can be formed.

[0303] Furthermore, the materials used for the insulating layer 2593 include, for example, resins such as acrylic and epoxy. In addition to resins containing siloxane bonds, silicon oxide, silicon oxide nitride, aluminum oxide Inorganic insulating materials such as MU can also be used.

[0304] Furthermore, an opening reaching the electrode 2591 is provided in the insulating layer 2593, and the wiring 2594 is adjacent to it. It is electrically connected to electrode 2591. The light-transmitting conductive material increases the aperture ratio of the touch panel. Because it can be done this way, it can be suitably used in wiring 2594. Also, electrode 2591 Furthermore, materials with higher conductivity than electrode 2592 are preferable for wiring 2594 because they can reduce electrical resistance. It can be used appropriately.

[0305] The electrode 2592 extends in one direction, and multiple electrodes 2592 are arranged in a stripe pattern. Furthermore, the wiring 2594 is provided intersecting with the electrode 2592.

[0306] A pair of electrodes 2591 are provided flanking one electrode 2592. Also, the wiring 2594 is A pair of electrodes 2591 are electrically connected.

[0307] Note that the multiple electrodes 2591 are not necessarily arranged in a direction perpendicular to that of a single electrode 2592. It is not necessary to do so; they may be positioned to form an angle greater than 0 degrees but less than 90 degrees.

[0308] Furthermore, wiring 2598 is electrically connected to electrode 2591 or electrode 2592. A portion of the wiring 2598 functions as a terminal. Wiring 2598 can be, for example, made of aluminum. Nium, gold, platinum, silver, nickel, titanium, tungsten, chromium, molybdenum, iron, corn Using metallic materials such as balsamic, copper, or palladium, or alloy materials containing such metallic materials. It is possible.

[0309] Furthermore, an insulating layer is provided to cover the insulating layer 2593 and the wiring 2594, and the touch sensor 2595 It may be protected.

[0310] Furthermore, the connecting layer 2599 electrically connects the wiring 2598 and the FPC2509(2). .

[0311] The connecting layer 2599 is an anisotropic conductive film (ACF: Anisotropic C (conductive film) or anisotropic conductive paste (ACP: Anisotropic) You can use tools such as IC Conductive Paste.

[0312] <Explanation regarding the touch panel 2> Next, we will explain the details of the touch panel 2000 using Figure 10(A). Figure 10 (A) corresponds to the cross-sectional view between the dashed line X5 and X6 shown in Figure 8(A).

[0313] The touch panel 2000 shown in Figure 10(A) is the same as the display device 2501 described in Figure 9(A). This configuration involves bonding the touch sensor 2595, as explained in Figure 9(C), to the other component.

[0314] Furthermore, the touch panel 2000 shown in Figure 10(A) is explained in Figures 9(A) and 9(C). In addition to the above configuration, it also has an adhesive layer 2597 and an anti-reflective layer 2567p.

[0315] 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. They are joined together. Furthermore, it is preferable that the adhesive layer 2597 has light-transmitting properties. Also, adhesive layer 2 For 597, a thermosetting resin or an ultraviolet curing resin can be used. For example, Using acrylic resin, urethane resin, epoxy resin, or siloxane resin It is possible.

[0316] The anti-reflective layer 2567p is provided in a position that overlaps with the pixel. For example, a circular polarizer can be used.

[0317] Next, for a touch panel with a configuration different from that shown in Figure 10(A), see Figure 10(B). I will use it to explain.

[0318] Figure 10(B) is a cross-sectional view of the touch panel 2001. The touch panel shown in Figure 10(B) Nell 2001 is a touch panel 2000 and a display device 2501 as shown in Figure 10(A). The position of the touch sensor 2595 is different. Here, we will explain the different configurations in detail. Where applicable, refer to the description of Touch Panel 2000 for details on how to use the provided configuration.

[0319] The colored layer 2567R is located in a position that overlaps with the light-emitting element 2550R. Also, in Figure 10(B) The light-emitting element 2550R shown emits light on the side where the transistor 2502t is located. As a result, some of the light emitted by the light-emitting element 2550R passes 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 in the diagram.

[0320] Furthermore, the touch sensor 2595 is located on the circuit board 2510 side of the display device 2501. .

[0321] The adhesive layer 2597 is located between substrate 2510 and substrate 2590 and touches the display device 2501. Attach the Chisensa 2595.

[0322] As shown in Figures 10(A) and 10(B), the light emitted from the light-emitting element is directed towards the upper and lower surfaces of the substrate. It is sufficient for the projectile to be fired at either one or both of these points.

[0323] <Explanation of how the touch panel is operated> Next, an example of a touch panel driving method will be explained using Figure 11.

[0324] Figure 11(A) is a block diagram showing the configuration of a mutually capacitive touch sensor. (A) shows the pulse voltage output circuit 2601 and the current detection circuit 2602. In Figure 11(A), the electrodes 2621 to which the pulse voltage is applied are designated as X1-X6, and the current changes... The electrodes 2622 that detect the change are shown as Y1-Y6, each represented by six wires. Furthermore, Figure 11(A) shows the capacitance formed by the superposition of electrode 2621 and electrode 2622. This indicates 2603. Note that electrodes 2621 and 2622 have interchangeable functions. You may do so.

[0325] The pulse voltage output circuit 2601 is a circuit for sequentially applying pulses to the X1-X6 wiring. Therefore, when a pulse voltage is applied to the wiring X1-X6, the capacitance 2603 is formed. An electric field is generated between pole 2621 and electrode 2622. This electric field generated between electrodes is affected by shielding, etc. By causing a change in the mutual capacitance of the 2603 capacitance, the proximity of the detected object, or It can detect contact.

[0326] The current detection circuit 2602 detects changes in the mutual capacitance of capacitor 2603, and the wiring of Y1-Y6 This is a circuit for detecting changes in current. In the wiring of Y1-Y6, proximity of the object to be detected, Alternatively, if there is no contact, the detected current value will not change, but if the object being detected is nearby, When the mutual capacitance decreases due to contact, a change in the current value is detected. Output can be performed using an integrating circuit or similar.

[0327] Next, Figure 11(B) shows the input of the mutual capacitive touch sensor shown in Figure 11(A). The timing chart of the output waveform is shown. Figure 11(B) shows the timing of each matrix in one frame period. The system will detect the object to be detected. Also, in Figure 11(B), the case where the object to be detected is not detected ( This shows two cases: one where the object to be detected is not touched, and another where the object to be detected is touched. Regarding the wiring of Y1-Y6, the waveforms shown represent the voltage values ​​corresponding to the detected current values. Yes, they are.

[0328] A pulse voltage is applied sequentially to the wiring of X1-X6, and Y1- The waveform changes in the Y6 wiring. If there is no proximity or contact with the detected object, X1-X6 The waveforms of Y1-Y6 change uniformly in response to changes in the voltage of the wiring. Meanwhile, when the object to be detected is nearby... Alternatively, at the point of contact, the current value decreases, and therefore the waveform of the corresponding voltage value also changes. ru.

[0329] In this way, by detecting changes in mutual capacitance, the proximity or contact of the object being detected can be detected. It is possible.

[0330] <Explanation regarding the sensor circuit> Furthermore, in Figure 11(A), only a capacitor 2603 is provided at the wiring intersection as a touch sensor. The configuration of a passive matrix type touch sensor is shown, but it has transistors and capacitors. It may also be an active-matrix type touch sensor. An example of a sensor circuit included in the sensor is shown in Figure 12.

[0331] The sensor circuit shown in Figure 12 consists of capacitor 2603, transistor 2611, and transistor It has transistor 2612 and transistor 2613.

[0332] Transistor 2613 receives a signal G2 at its gate, and either its source or drain... A voltage VRES is applied, and the other side is one electrode of capacitor 2603 and transistor 2611 It is electrically connected to the gate. Transistor 2611 has either the source or the drain Electrically connect either the source or drain of transistor 2612, and apply a voltage VS to the other side. S is given. Transistor 2612 is given a signal G1 at its gate, and source or The other end of the drain is electrically connected to the wiring ML. The other electrode of the 2603 capacitance has a voltage VS. S is given.

[0333] Next, we will explain the operation of the sensor circuit shown in Figure 12. First, the signal G2 is a transistor When a potential is applied that turns on transistor 2613, the gate of transistor 2611 A potential corresponding to the voltage VRES is applied to node n to which the signal G2 is connected. Next, the signal G2 and By applying a potential that turns off transistor 2613, the potential at node n becomes It is retained.

[0334] Next, the mutual capacitance of capacitance 2603 changes due to the proximity or contact of a detected object such as a finger. Consequently, the potential of node n changes from VRES.

[0335] The read operation applies a potential to signal G1 that turns on transistor 2612. The current flowing through transistor 2611, i.e., the current flowing through wiring ML, is determined by the potential of the current n. The current changes. By detecting this current, the proximity or contact of the object to be detected can be detected. It is possible.

[0336] As for transistors 2611, 2612, and 2613, It is preferable to use an oxide semiconductor layer as the semiconductor layer in which the channel region is formed. In particular, By applying such a transistor to the transistor 2613, the potential at node n can be changed. This makes it possible to retain the data for a long period of time, and the operation of resupplying VRES to node n ( This can reduce the frequency of fresh operations.

[0337] The configuration shown in this embodiment may be used in appropriate combination with the configurations shown in other embodiments. It is possible.

[0338] (Embodiment 6) In this embodiment, a display module and electronic device having a light-emitting element according to one aspect of the present invention This will be explained using Figures 13 and 14.

[0339] <Explanation regarding the display module> The display module 8000 shown in Figure 13 consists of an upper cover 8001 and a lower cover 8002. In between, touch sensor 8004 connected to FPC8003, and FPC8005 connected It has a display device 8006, a frame 8009, a printed circuit board 8010, and a battery 8011. do.

[0340] A light-emitting element according to one aspect of the present invention can be used, for example, in a display device 8006.

[0341] The upper cover 8001 and the lower cover 8002 are connected to the touch sensor 8004 and the display device 8 The shape and dimensions can be appropriately modified to match the size of 006.

[0342] The touch sensor 8004 is a resistive or capacitive touch sensor connected to the display device 8 It can be used superimposed on 006. Also, the opposing substrate (encapsulation substrate) of the display device 8006 It is also possible to give it a touch sensor function. Furthermore, the display device 8006 It is also possible to install a light sensor within each pixel to create an optical touch sensor.

[0343] Frame 8009 provides protection for the display device 8006, as well as the operation of the printed circuit board 8010. It has the function of an electromagnetic shield to block electromagnetic waves generated by [unclear]. The Mu8009 may also function as a heat sink.

[0344] The printed circuit board 8010 contains power supply circuits and signals for outputting video and clock signals. It has a power processing circuit. The power supply that provides power to the power supply circuit is an external commercial power supply. Alternatively, a separate power source, the battery 8011, may also be used. This can be omitted when using commercial power.

[0345] Furthermore, the display module 8000 includes components such as polarizing plates, phase difference plates, and prism sheets. They may also be provided.

[0346] <Explanation regarding electronic equipment> Figures 14(A) through 14(G) show electronic devices. These electronic devices are enclosed in a casing. Body 9000, display unit 9001, speaker 9003, operation keys 9005 (power switch, or (including the operating switch), connection terminal 9006, sensor 9007 (force, displacement, position, velocity, Acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substances, sound, time, hardness, electricity To measure fields, currents, voltages, power, radiation, flow rates, humidity, gradients, vibrations, odors, or infrared radiation. It may have a microphone 9008 (including functions), etc.

[0347] The electronic devices shown in Figures 14(A) to 14(G) can have a variety of functions. For example, a function that displays various information (still images, videos, text images, etc.) on the display unit, Chiss sensor function, calendar, date or time display function, various software ( The program controls processing, provides wireless communication, and uses wireless communication to perform various tasks. Features include the ability to connect to computer networks and transmit various types of data using wireless communication. Alternatively, it can perform receiving functions, or read programs or data recorded on a recording medium and display them. It can have a function to display on the display unit, etc. Note that Figures 14(A) to 14(G) The functions that the electronic devices shown may have are not limited to these, and may have a variety of functions. This is possible. Also, although not shown in Figures 14(A) to 14(G), electronic devices include: The configuration may have multiple display units. Furthermore, the electronic device may be equipped with a camera or the like to capture still images. Functions for taking photos, recording videos, and recording images on a storage medium (external or built into the camera). It may also have a function to save the image to the display unit, a function to display the captured image on the display unit, etc.

[0348] Details of the electronic equipment shown in Figures 14(A) to 14(G) will be explained below.

[0349] Figure 14(A) is a perspective view showing the personal digital assistant 9100. The display unit 9001 has flexibility. Therefore, it can be used on the curved surface of the curved housing 9000. The display unit 9001 can be incorporated accordingly. Furthermore, the display unit 9001 is a touch sensor. It features a stylus that allows you to operate it by touching the screen with your finger or a stylus. For example, the display By touching the icon displayed on the display unit 9001, you can launch the application. can.

[0350] Figure 14(B) is a perspective view showing the personal digital assistant 9101. The personal digital assistant 9101 is It has one or more functions selected from, for example, a telephone, a notebook, or an information viewing device. Physically, it can be used as a smartphone. Furthermore, the mobile information terminal 9101 is... The speaker 9003, connection terminal 9006, sensor 9007, etc. are omitted from the diagram, but It can be installed in the same position as the portable information terminal 9100 shown in 14(A). The information terminal 9101 can display text and image information on its multiple surfaces. For example, Three operation buttons 9050 (also called operation icons or simply icons) are on the display unit 900. It can be displayed on one side of 1. Also, the information 9051 shown by the dashed rectangle is displayed on the display unit 90 It can be displayed on other sides of 01. For example, information 9051 is an email. A display that notifies you of incoming calls from social networking services (SNS) or phone calls. Subject of email or social media post, sender's name, date and time, time, This includes battery level, antenna signal strength, etc. Alternatively, information 9051 may be displayed. Instead of displaying information 9051, you may also display an operation button 9050 or the like at that location.

[0351] Figure 14(C) is a perspective view showing the personal digital assistant 9102. The personal digital assistant 9102 is The display unit 9001 has the function of displaying information on three or more sides. Here, information 9052, This shows an example where information 9053 and information 9054 are displayed on different sides. For example, The user of the mobile information terminal 9102 stores the mobile information terminal 9102 in the breast pocket of their clothing. In this state, you can check the display (information 9053 in this case). Specifically, when an incoming call is received... The phone number or name of the caller can be observed from above the mobile information terminal 9102. The information is displayed on the device. The user can view the information without taking the portable information terminal 9102 out of their pocket. This allows you to check and decide whether or not to answer the call.

[0352] Figure 14(D) is a perspective view showing the wristwatch-type personal information terminal 9200. Personal information terminal The 9200 is a mobile phone, email, document viewing and creation, music playback, and internet communication. It can run various applications such as computer games. The display unit 9001 has a curved display surface, and displays are performed along the curved display surface. It can do this. Furthermore, the personal information terminal 9200 can perform standardized short-range wireless communication. This is possible. For example, by communicating with a wireless headset, It is also possible to make calls using the free-call function. In addition, the mobile information terminal 9200 has a connection terminal 9006. It has the capability to directly exchange data with other information terminals via a connector. Charging can also be performed via connection terminal 9006. Note that the charging operation is performed via connection terminal 900 This may also be done by wireless power transfer without using 6.

[0353] Figures 14(E), (F), and (G) are perspective views showing a foldable portable information terminal 9201. Furthermore, Figure 14(E) is a perspective view of the mobile information terminal 9201 in an unfolded state, and Figure 14 (F) changes the mobile information terminal 9201 from one state to the other, either unfolded or folded. This is a perspective view of the device in the process of being folded, with Figure 14(G) showing the portable information terminal 9201 in its folded state. This is a perspective view of the device. The 9201 portable information terminal offers excellent portability when folded, and when unfolded... In this configuration, the seamless, wide display area provides excellent readability. (Portable Information Terminal 92) The display unit 9001 of 01 is connected by three housings 9000 via a hinge 9055. It is supported by bending the two housings 9000 via the hinge 9055. Furthermore, the mobile information terminal 9201 can be reversibly transformed from an unfolded state to a folded state. This is possible. For example, the mobile information terminal 9201 can bend with a radius of curvature of 1 mm or more and 150 mm or less. It is possible to do so.

[0354] The electronic device described in this embodiment has a display unit for displaying some kind of information. The present invention is characterized by the fact that, however, the light-emitting element in one aspect of the present invention is an electronic device that does not have a display unit. It can also be applied to the display unit of the electronic device described in this embodiment. In other words, a configuration that is flexible and can display along a curved display surface, or a folding While examples of foldable display unit configurations have been given, the system is not limited to these, and may also include non-flexible, planar displays. The display may also be configured to appear in the section.

[0355] The configuration shown in this embodiment may be used in appropriate combination with the configurations shown in other embodiments. It is possible.

[0356] (Embodiment 7) This embodiment describes an example of a lighting device that applies a light-emitting element, which is one aspect of the present invention. This will be explained using Figure 15.

[0357] Figure 15 shows an example in which the light-emitting element is used as an indoor lighting device 8501. Because it can be scaled up to cover a large area, it can also be used to form large-area lighting devices. In addition, curved surfaces By using a housing having the above characteristics, a lighting device 8502 having a curved surface in the light-emitting area can be formed. This is also possible. The light-emitting element shown in this embodiment is a thin film, which allows for a high degree of freedom in the design of the housing. Therefore, lighting devices with various elaborate designs can be created. Furthermore, indoor A large lighting fixture 8503 may be installed on the wall. Also, lighting fixtures 8501, 8502, 8 A touch sensor may be provided in 503 to turn the power on or off.

[0358] Furthermore, by using the light-emitting element on the surface side of the table, it is equipped with the functionality of a table. It can be a lighting device 8504. Furthermore, light-emitting elements can be used in other parts of the furniture. This allows for the creation of a lighting device that also functions as furniture.

[0359] As described above, various lighting devices can be obtained by applying light-emitting elements. The arrangement is included in one aspect of the present invention.

[0360] Furthermore, the configuration shown in this embodiment can be used in appropriate combination with the configurations shown in other embodiments. It is possible to be there. [Examples]

[0361] This embodiment shows an example of fabricating a light-emitting element according to one aspect of the present invention, as well as a comparative light-emitting element. In addition, in this embodiment, light-emitting elements 1 to 7 were fabricated.

[0362] Note that light-emitting elements 1, 2, 5, and 7 are comparative light-emitting elements. Yes, light-emitting element 3, light-emitting element 4, and light-emitting element 6 are light-emitting elements according to one embodiment of the present invention. Furthermore, light-emitting element 1 is a host-guest system light-emitting element, and light-emitting elements 2, 5, and The light-emitting element 7 is a light-emitting element that utilizes excyplex emission, and the light-emitting element 3 emits light. Element 4 and light-emitting element 6 are light-emitting elements that utilize ExSET.

[0363] Figure 16 shows schematic cross-sectional diagrams of light-emitting elements 1 to 7, and Tables 4 and 5 show detailed information on the element structure. The structures and abbreviations of the compounds used are shown below.

[0364] [ka]

[0365] [ka]

[0366] [Table 4]

[0367] [Table 5]

[0368] <1-1. Method for fabricating the light-emitting element 1> First, on the substrate 1100, an electrode 1101 is made of indium tin oxide containing silicon oxide (omitted) The film was deposited using the sputtering method with the name: ITSO. The film thickness of electrode 1101 was set to 110 The area of ​​electrode 1101 is set to nm and 4 mm². 2 (2mm x 2mm)

[0369] Next, as a pretreatment before depositing the organic compound layer, the electrode 1101 side of the substrate 1100 is washed with water. After cleaning and firing at 200°C for 1 hour, the surface of electrode 1101 was subjected to UV ozone treatment for 37 minutes. It went 0 seconds.

[0370] Then, 1 × 10 -4 The substrate 1100 is introduced into a vacuum deposition apparatus where the internal pressure is reduced to approximately Pa. After being placed in the heating chamber of the vacuum deposition apparatus and subjected to vacuum firing at 170°C for 30 minutes, the base The plate 1100 was allowed to cool for about 30 minutes.

[0371] Next, the substrate 1100 is placed in the vacuum deposition apparatus so that the surface on which the electrode 1101 is formed faces downwards. It was fixed in a holder provided inside. In this embodiment, the hole injection layer 11 was formed by vacuum deposition. 11. Hole transport layer 1112, light-emitting layer 1113, electron transport layer 1115, electron injection layer 1116 Next, electrodes 1102 were formed sequentially. The detailed fabrication method is described below.

[0372] First, on electrode 1101, DBT3P-II and molybdenum oxide are used as a hole injection layer 1111. Den (abbreviation: MoO3) and DBT3P-II:molybdenum oxide = 2:1 (weight ratio) The co-deposition was carried out in such a manner. The thickness of the hole injection layer 1111 was set to 20 nm.

[0373] Next, a hole transport layer 1112 was formed on the hole injection layer 1111. Next, BPAFLP was deposited. The thickness of the hole transport layer 1112 was set to 20 nm.

[0374] Next, a light-emitting layer 1113 was formed on the hole transport layer 1112. The light-emitting layer 1113 was made of 4 ,6mCzP2Pm and Rubrene, 4,6mCzP2Pm:Ru Co-deposition was performed so that brene = 1:0.005 (weight ratio). Note that the luminescent layer 1113 The film thickness was set to 40 nm. In addition, in the light-emitting layer 1113, 4,6 mCzP2Pm is present. It is a base material, and Rubrene is a guest material.

[0375] Next, an electron transport layer 1115 with a thickness of 10 nm is applied to the light-emitting layer 1113, specifically a 4,6 mCzP layer. 2Pm and a 15nm film of bathophenanthroline (abbreviated as Bphen) were sequentially deposited. Next, a lithium fluoride layer with a thickness of 1 nm is added as an electron injection layer 1116 on the electron transport layer 1115. LiF (abbreviated as LiF) was deposited onto the surface.

[0376] Next, aluminum (Al) was deposited on the electron injection layer 1116 as an electrode 1102. The film thickness of electrode 1102 was set to 200 nm.

[0377] The light-emitting element on the substrate 1100 prepared as described above and the encapsulating substrate 1150 are exposed to the atmosphere. To prevent leakage, the glove box was sealed by bonding the parts together in a nitrogen atmosphere. Specifically, a sealing material is applied around the light-emitting element on the substrate 1100, sealing it to the substrate 1100. After bonding substrate 1150, 365nm ultraviolet light at 6J / cm² is applied to the sealing material. 2 Irradiate, The product was heat-treated at 80°C for 1 hour.

[0378] The light-emitting element 1 was fabricated through the above process.

[0379] <1-2. Method for fabricating the light-emitting element 2> The light-emitting element 2 has a different configuration from the light-emitting element 1 described above and the light-emitting layer 1113. The composition is the same as that of light-emitting element 1.

[0380] The light-emitting layer 1113 of the light-emitting element 2 consists of 4,6mCzP2Pm and PCBBiF. Co-deposited so that 4,6mCzP2Pm:PCBBiF = 0.8:0.2 (weight ratio) The film thickness of the light-emitting layer 1113 was set to 40 nm. 4,6mCzP2Pm is the host material, and PCBBiF is the assist material.

[0381] <1-3. Method for fabricating the light-emitting element 3> The light-emitting element 3 has a different configuration from the light-emitting element 1 described above and the light-emitting layer 1113. The composition is the same as that of light-emitting element 1.

[0382] The light-emitting layer 1113 of the light-emitting element 3 consists of 4,6mCzP2Pm, PCBBiF, and R ubrene and 4,6mCzP2Pm:PCBBiF:Rubrene=0.8:0 Co-deposition was performed in a ratio of 0.2:0.005 (by weight). The film thickness of the light-emitting layer 1113 was 4 It was set to 0 nm. In addition, in the light-emitting layer 1113, 4,6 mCzP2Pm is the host material. PCBBiF is the assisting material, and Rubrene is the guest material.

[0383] <1-4. Method for fabricating the light-emitting element 4> The light-emitting element 4 has a different configuration from the light-emitting element 1 described above and the light-emitting layer 1113. The composition is the same as that of light-emitting element 1.

[0384] The light-emitting layer 1113 of the light-emitting element 4 consists of 4,6mCzP2Pm, PCBBiF, and R ubrene and 4,6mCzP2Pm:PCBBiF:Rubrene=0.8:0 Co-deposition was performed in a ratio of 0.2:0.01 (by weight). The film thickness of the light-emitting layer 1113 was 40 The value was set to nm. In addition, in the light-emitting layer 1113, 4,6 mCzP2Pm is the host material. PCBBiF is the assisting material, and Rubrene is the guest material. The concentration of the guest material differs between element 3 and light-emitting element 4.

[0385] <1-5. Method for fabricating the light-emitting element 5> The light-emitting element 5 consists of the light-emitting element 1 described above, the configuration of the light-emitting layer 1113 and the electron transport layer 11 The configuration of element 15 is different. The other configurations are the same as those of element 1.

[0386] The light-emitting layer 1113 of the light-emitting element 5 is 4-{3-[3'-(9H-carbazole-9 (-yl)biphenyl-3-yl}benzoflo[3,2-d]pyrimidine (abbreviation: 4mC) zBPBfPm) and 3-[N-(9-phenylcarbazole-3-yl)-N-phenyl Luamino-9-phenylcarbazole (abbreviation: PCzPCA1) and 4mCzBPB Co-deposition was performed with a ratio of fPm:PCzPCA1 = 0.8:0.2 (by weight). The film thickness of layer 1113 was set to 40 nm. Furthermore, in the light-emitting layer 1113, 4 mCz BBP fPm is the host material, and PCzPCA1 is the assist material.

[0387] The electron transport layer 1115 of the light-emitting element 5 is made of 4mCzBPBfPm with a film thickness of 20nm and film thickness 1 We assumed Bphen to be 0 nm.

[0388] <1-6. Method for fabricating the light-emitting element 6> The light-emitting element 6 consists of the light-emitting element 1 described above, the configuration of the light-emitting layer 1113 and the electron transport layer 11 The configuration of element 15 is different. The other configurations are the same as those of element 1.

[0389] The light-emitting layer 1113 of the light-emitting element 6 consists of 4,6mCzP2Pm and PCzPCA1, Rubrene and 4,6mCzP2Pm:PCzPCA1:Rubrene=0.8 Co-deposition was performed in a ratio of 0.2:0.01 (by weight). The film thickness of the light-emitting layer 1113 was as follows: The wavelength was set to 40 nm. In addition, in the light-emitting layer 1113, 4,6 mCzP2Pm is the host material. Yes, PCzPCA1 is the assisting material and Rubrene is the guest material.

[0390] The electron transport layer 1115 of the light-emitting element 6 is 4,6mCzP2Pm with a film thickness of 20nm and film thickness 1 We assumed Bphen to be 0 nm.

[0391] <1-7. Method for fabricating the light-emitting element 7> The light-emitting element 7 consists of the light-emitting element 1 described above, the configuration of the light-emitting layer 1113 and the electron transport layer 11 The configuration of element 15 is different. The other configurations are the same as those of element 1.

[0392] The light-emitting layer 1113 of the light-emitting element 7 consists of 4,6mCzP2Pm and PCzPCA1. Co-deposition is performed so that the ratio of 4,6mCzP2Pm:PCzPCA1 is 0.8:0.2 (by weight). The film thickness of the light-emitting layer 1113 was set to 40 nm. 4,6mCzP2Pm is the host material, and PCzPCA1 is the assist material.

[0393] The electron transport layer 1115 of the light-emitting element 7 is 4,6mCzP2Pm with a film thickness of 20nm and film thickness 1 We assumed Bphen to be 0 nm.

[0394] In addition, in the deposition process of the light-emitting elements 1 to 7 described above, the deposition method is resistive deposition. A heat method was used.

[0395] <1-8. Characteristics of light-emitting elements 1 to 7> Figure 17 shows the brightness-current density characteristics of light-emitting elements 1 to 4, and Figure 19 shows the brightness-voltage characteristics. Figure 21 shows the current efficiency-luminance characteristics, Figure 23 shows the current-voltage characteristics, and Figure 23 shows the external quantum efficiency-luminance characteristics. The properties are shown in Figure 25. Furthermore, the brightness-current density characteristics of light-emitting elements 5 to 7 are shown. Figure 18 shows the luminance-voltage characteristics, Figure 20 shows the current efficiency-luminance characteristics, and Figure 22 shows the current-voltage characteristics. Figure 24 shows the external quantum efficiency-luminance characteristics, and Figure 26 shows the external quantum efficiency-luminance characteristics, respectively. The test was conducted at room temperature (an atmosphere maintained at 25°C).

[0396] Furthermore, Table 6 shows the device characteristics of light-emitting elements 1 to 7 when the external quantum efficiency is at its maximum.

[0397] [Table 6]

[0398] Furthermore, 2.5 mA / cm² is transmitted to light-emitting elements 1 through 4. 2 When current flows at this current density The field emission spectra are shown in Figure 27. Additionally, 2.5 mA / c was applied to light-emitting elements 5 through 7. m 2 Figure 28 shows the field emission spectrum when a current is passed through at the given current density.

[0399] Furthermore, the emission spectra of thin films of 4,6mCzP2Pm and PCBBiF alone were measured. The peak wavelengths were found to be 439 nm and 436 nm, respectively. Meanwhile, as shown in Figure 27... As shown above, the peak wavelength of the electroluminescence spectrum of the light-emitting element 2 was 527 nm. Furthermore, the light-emitting element 2 emits light differently from the light emitted by 4,6mCzP2Pm and PCBBiF respectively. The spectrum is shown, and the electroluminescence spectrum of the light-emitting element 2 is 4,6 mCzP2Pm and This is the luminescence exhibited by the excited complex formed by PCBBiF.

[0400] Furthermore, the emission spectra of thin films containing 4mCzBPBfPm and PCzPCA1 alone were measured. The peak wavelengths were found to be 440 nm and 443 nm, respectively. Meanwhile, Figure 28 shows As shown, the peak wavelength of the electroluminescence spectrum of the light-emitting element 5 was 567 nm. In other words, the light-emitting element 5 emits light differently from 4mCzBPBfPm and PCzPCA1 respectively. The emission spectrum is shown, and the field emission spectrum of the light-emitting element 5 is 4mCzBPBfP This is the luminescence exhibited by the excited complex formed by m and PCzPCA1. Also, as shown in Figure 28... Therefore, the peak wavelength of the field emission spectrum of the light-emitting element 7 was 558 nm. The light-emitting element 7 emits light differently from 4,6mCzP2Pm and PCzPCA1 respectively. The vector is shown, and the electroluminescence spectrum of the light-emitting element 7 is 4,6 mCzP2Pm and This is the luminescence exhibited by the excited complex formed with PCzPCA1.

[0401] Furthermore, as shown in Figures 27 and 28, the light-emitting element 1, light-emitting element 3, light-emitting element 4, and The optical element 6 shows the emission spectrum exhibited by the guest material rubrene, and the electric field The peak wavelengths of the emission spectra are 557 nm, 553 nm, 559 nm, and 5 It was 57 nm. Therefore, light-emitting element 2 has a shorter wavelength than light-emitting elements 3 and 4. The presence of a peak emission wavelength indicates that it possesses high emission energy, as shown in 4,6 The excited complex formed by mCzP2Pm and PCBBiF is an excited complex that uses rubrene as a guest material. It can be seen that it can be used as a host material for optical elements. Also, the light-emitting element 6 and the light-emitting element Since it exhibits a similar emission peak wavelength to child 7, it has a similar emission energy. However, from the results of the electroluminescence spectra of light-emitting elements 6 and 7, 4,6 mCz The excited complex formed by P2Pm and PCzPCA1 is a luminescent element that uses rubrene as a guest material. It can be seen that it can be used as host material for the child.

[0402] Furthermore, the phosphorescence spectra of 4,6mCzP2Pm, PCBBiF, and PCzPCA1 were obtained. Measurements revealed that the shortest peak wavelengths were 459nm, 509nm, and 49nm, respectively. The peak wavelength is 5 nm, and the phosphorescence emission energy determined from this peak wavelength is 2.70 eV. The calculated values ​​were 2.44 eV and 2.51 eV. The phosphorescence spectrum measurement method was as follows: The method shown in Form 1 was used. The excited complex was subjected to singlet excitation energy levels and triplet excitation. Because the electromotive force levels are close together, the phosphorescence spectrum of the excited complex is like that of a firefly. It is considered identical to the light spectrum (emission spectrum of thermally activated delayed fluorescence).

[0403] Furthermore, as shown in Embodiment 1, the calculated value of the triplet excitation energy level of rubrene is The voltage was 0.95 eV.

[0404] Based on the above results, the phosphorescence spectra of 4,6mCzP2Pm and PCBBiF are as follows: The wavelengths are shorter than the phosphorescence spectra of the excited complexes formed by 4,6mCzP2Pm and PC. The triplet excitation energy levels of BBiF are determined by the triplet excitation energy of the excited complex formed by both materials. It is higher than the Ghee level. Furthermore, the triplet excitation energy level of the excited complex is higher than that of the guest material. It is higher than the triplet excitation energy level of rubrene. Also, 4,6mCzP2Pm and PC The phosphorescence spectrum of zPCA1 has a shorter wavelength than the emission spectrum of the excited complex formed by both materials. Therefore, the triplet excitation energy levels of 4,6mCzP2Pm and PCBBiF are the same for both materials. It is higher than the triplet excitation energy level of the excited complex formed by it. Furthermore, the triplet of the excited complex The excitation energy level is higher than the triplet excitation energy level of the guest material, rubrene. Therefore, 4,6mCzP2Pm, PCBBiF, and PCzPCA1 are part of the present invention. It is suitable as a host material for one embodiment of a light-emitting element.

[0405] As shown in Figures 17 to 26 and Table 6, the maximum value of the external quantum efficiency of the light-emitting element 1 is 4 The maximum external quantum efficiency of light-emitting element 2 is 0.6%, and the external quantum efficiency of light-emitting element 3 is 17%. The maximum quantum efficiency is 8.9%, and the maximum external quantum efficiency of the light-emitting element 4 is 6.8%. Therefore, the maximum external quantum efficiency of light-emitting element 5 is 11%, and the external quantum efficiency of light-emitting element 6 is 11%. The maximum efficiency was 9.4%, and the maximum external quantum efficiency of the light-emitting element 7 was 11%. .

[0406] The maximum external quantum efficiencies of light-emitting elements 2, 5, and 7 are high, but the high-brightness region A phenomenon called roll-off occurs in which efficiency drops sharply in the region. On the other hand, the present invention In the embodiment, light-emitting element 3, light-emitting element 4, and light-emitting element 6 are compared with light-emitting element 1. Furthermore, the maximum value of the external quantum efficiency has been improved, and the light-emitting element 2, light-emitting element 5, and light-emitting element The roll-off observed in 7 is also suppressed. This is because ExSET, one embodiment of the present invention, This is an excellent effect that can only be achieved through this method.

[0407] Furthermore, as shown in Figures 17 to 26 and Table 6, a light-emitting element according to one embodiment of the present invention is When comparing the optical element 3, the light-emitting element 4, and the light-emitting element 6, the light-emitting element 6 exhibits high luminous efficiency. It exhibits excellent characteristics, particularly with a high maximum external quantum efficiency of 9.4%. So, in order to investigate whether the light-emitting element 6 is emitting light using ExSET, light-emitting element 1, Transient EL measurements were performed on element 6 and light-emitting element 7. Light-emitting element 1, light-emitting element 6, Figure 29 shows the transient EL characteristics of the light-emitting element 7. Also, the transient EL spectrum of the light-emitting element 6 is shown in Figure 29. This is shown in 30.

[0408] <1-9. Transient EL measurement of light-emitting element 1, light-emitting element 6, and light-emitting element 7> A picosecond fluorescence lifetime measurement system (manufactured by Hamamatsu Photonics) was used for the measurement. In this measurement, To measure the transient EL characteristics of the light-emitting element, a rectangular pulse voltage is applied to the light-emitting element, and the voltage The light emission, which decays from the falling edge, was measured in time-resolved mode using a streak camera. The test was conducted at room temperature (25°C).

[0409] In Figure 29, the vertical axis represents the state in which carriers are steadily being injected (pulse voltage ON). The intensity is shown normalized by the luminescence intensity at (time). The horizontal axis is from the falling edge of the pulse voltage. This indicates the elapsed time.

[0410] From the transient EL characteristics shown in Figure 29, light-emitting elements 6 and 7 have a longer emission life than light-emitting element 1. It was found to have a long lifespan and exhibit delayed fluorescence based on reverse intersystem crossing.

[0411] Furthermore, in Figure 30, prompt EL is the value in the measured transient EL spectrum. The initial component is the voltage, and delayed EL is the delayed component. The luminescence component during application is defined as the luminescence component occurring 8 μs to 45 μs after the voltage is applied, and the delayed component is defined as the luminescence component occurring 8 μs to 45 μs after the voltage is applied. I divided it into minutes.

[0412] As shown in Figure 30, both the initial and delayed EL spectra show that the guest material is Rub It roughly matches the emission spectrum of Len. Therefore, S E Initial exciton (injected) (singlet excitons directly generated by carrier recombination) and S generated by reverse intersystem crossing E Delayed excitons (singlet excitons generated by the reverse intersystem crossing of triplet excitons) and both of the Energy is Rubren's S G It is suggested that this movement contributes to the luminescence.

[0413] As described above, by using ExSET, the light-emitting element of one embodiment of the present invention has high light emission. It was confirmed to be efficient.

[0414] The configuration shown in this embodiment can be used in appropriate combination with other embodiments and models. It is possible. [Examples]

[0415] This embodiment shows an example of fabricating a light-emitting element according to one aspect of the present invention, as well as a comparative light-emitting element. In this embodiment, light-emitting elements 8 and 9 were fabricated.

[0416] Furthermore, the light-emitting element 8 is a light-emitting element according to one embodiment of the present invention utilizing ExSET, and the light-emitting element Sub-element 9 is a comparative light-emitting element that utilizes excyplex emission. Figure 16 shows a schematic cross-sectional view of the optical element 9, Table 7 shows the detailed structure of the element, and Table 7 shows the structure of the compound used. The names are shown below. Note that, except for the compounds listed below, the same compounds as those shown in Example 1 are used. Used.

[0417] [ka]

[0418] [Table 7]

[0419] <2-1. Method for fabricating the light-emitting element 8> First, ITSO is deposited on the substrate 1100 as an electrode 1101 by sputtering. The film thickness of electrode 1101 was set to 70 nm, and the area of ​​electrode 1101 was set to 4 mm². 2 (2m (m × 2mm)

[0420] Next, as a pretreatment before depositing the organic compound layer, the electrode 1101 side of the substrate 1100 is washed with water. After cleaning and firing at 200°C for 1 hour, the surface of electrode 1101 was subjected to UV ozone treatment for 37 minutes. It went 0 seconds.

[0421] Then, 1 × 10 -4 The substrate 1100 is introduced into a vacuum deposition apparatus where the internal pressure is reduced to approximately Pa. After being placed in the heating chamber of the vacuum deposition apparatus and subjected to vacuum firing at 170°C for 30 minutes, the base The plate 1100 was allowed to cool for about 30 minutes.

[0422] Next, the substrate 1100 is placed in the vacuum deposition apparatus so that the surface on which the electrode 1101 is formed faces downwards. It was fixed in a holder provided inside. In this embodiment, the hole injection layer 11 was formed by vacuum deposition. 11. Hole transport layer 1112, light-emitting layer 1113, electron transport layer 1115, electron injection layer 1116 Next, electrodes 1102 were formed sequentially. The detailed fabrication method is described below.

[0423] First, on electrode 1101, DBT3P-II and molybdenum oxide are used as a hole injection layer 1111. The densate was co-deposited in a ratio of DBT3P-II:molybdenum oxide = 2:1 (by weight). Furthermore, the thickness of the hole injection layer 1111 was set to 15 nm.

[0424] Next, a hole transport layer 1112 was formed on the hole injection layer 1111. Therefore, 3,5-di(carbazole-9-yl)-N,N-diphenylaniline (abbreviation: DPhAmCP was deposited. The thickness of the hole transport layer 1112 was set to 20 nm.

[0425] Next, a light-emitting layer 1113 was formed on the hole transport layer 1112. The light-emitting layer 1113 was made of 4 mCzBPBfPm, DPhAmCP, and 1,6mMemFLPAPrn are 4mC zBPBfPm:DPhAmCP:1,6mMemFLPAPrn=0.8:0.2:0 Co-deposition was performed to a weight ratio of 0.005. The film thickness of the light-emitting layer 1113 was 30 nm. In addition, in the light-emitting layer 1113, 4mCzBPBfPm is the host material, and DP hAmCP is the assisting material, and 1,6mMemFLPAPrn is the guest material.

[0426] Next, an electron transport layer 1115 with a film thickness of 10 nm is applied to the light-emitting layer 1113, specifically a 4 mCz BPB layer. fPm and Bphen with a film thickness of 15 nm were sequentially deposited. Next, electron transport layer 1115 was deposited. A 1 nm thick layer of LiF was deposited as the sub-injection layer 1116.

[0427] Next, Al was deposited on the electron injection layer 1116 as electrode 1102. The film thickness of O2 was set to 200 nm.

[0428] The light-emitting element on the substrate 1100 prepared as described above and the encapsulating substrate 1150 are exposed to the atmosphere. To prevent leakage, the glove box was sealed by bonding the parts together in a nitrogen atmosphere. The sealing method is the same as that for the light-emitting element 1 shown in Example 1.

[0429] The light-emitting element 8 was fabricated through the above process.

[0430] <2-2. Method for fabricating the light-emitting element 9> The light-emitting element 9 has a different configuration from the light-emitting element 8 described above and the light-emitting layer 1113. The composition is the same as that of the light-emitting element 8.

[0431] The light-emitting layer 1113 of the light-emitting element 9 consists of 4mCzBPBfPm and DPhAmCP, This is done by co-evaporating the particles so that the ratio is 4mCzBPBfPm:DPhAmCP = 0.8:0.2 (by weight). It arrived. The film thickness of the light-emitting layer 1113 was set to 40 nm. Therefore, 4mCzBPBfPm is the host material, and DPhAmCP is the assist material.

[0432] In addition, in the deposition process of the light-emitting elements 8 and 9 described above, the deposition method is resistive deposition. A heat method was used.

[0433] <2-3. Characteristics of light-emitting elements 8 and 9> Figure 31 shows the brightness-current density characteristics of light-emitting elements 8 and 9, and Figure 32 shows the brightness-voltage characteristics. Figure 33 shows the current efficiency-luminance characteristics, Figure 34 shows the current-voltage characteristics, and Figure 34 shows the external quantum efficiency-luminance characteristics. The properties are shown in Figure 35. Note that the measurements of each light-emitting element were taken at room temperature (at an atmosphere maintained at 25°C). I went there.

[0434] Table 8 also shows the device characteristics of light-emitting elements 8 and 9 when the external quantum efficiency is at its maximum.

[0435] [Table 8]

[0436] Furthermore, 2.5 mA / cm² is supplied to light-emitting elements 8 and 9. 2 When current flows at this current density The field emission spectrum is shown in Figure 36.

[0437] As shown in Figure 36, light-emitting elements 8 and 9 emit an electric field emission spectrum in the blue wavelength band. It has a torque. The host material used in the light-emitting element 8 and light-emitting element 9 is 4mCz The emission spectra of individual thin films of BPBfPm and the assisting material DPhAmCP were measured. The peak wavelengths were determined to be 440 nm and 375 nm, respectively. The peak wavelength of the electroluminescence spectrum of child 9 was 457 nm. That is, light-emitting element 9 It exhibits emission spectra different from those of 4mCzBPBfPm and DPhAmCP, respectively. The electroluminescent spectrum of the light-emitting element 9 is 4mCzBPBfPm and DPhAmCP. This is the luminescence exhibited by the excited complex formed by the reaction.

[0438] Furthermore, the electroluminescence spectrum of the light-emitting element 8 has a peak wavelength of 465 nm, which is typical for guest materials. It exhibits an emission spectrum from a certain 1,6mMemFLPAPrn, and 4mCzBP No luminescence is observed from the excited complex formed by BfPm and DPhAmCP. Element 9 exhibits an emission peak with a shorter wavelength than the light-emitting element 8, and has high emission energy. It can be seen that the excited complex formed in the light-emitting element 8 is It can be said that the energy is being efficiently transferred to the guest material.

[0439] That is, it has a condensed heterocyclic skeleton, such as 4mCzBPBfPm, and the condensed heterocyclic skeleton Compounds having a diazine skeleton can be suitably used in blue light-emitting devices. Like DPhAmCP, the carbazole skeleton and the aromatic amine skeleton are... Compounds that bond at the 9th position can be suitably used in blue light-emitting devices. Like 4mCzBPBfPm, it has a condensed heterocyclic skeleton, and the condensed heterocyclic skeleton is a diazine skeleton Compounds having a specific structure, and like DPhAmCP, a carbazole skeleton and an aromatic amine skeleton However, the compound bonded at position 9 of the carbazole skeleton and the excited complex formed by them produce a blue emission. It can be suitably used as a host material for optical elements.

[0440] Furthermore, as shown in Figures 31 to 35 and Table 8, the light-emitting element 8 in one embodiment of the present invention is blue As a light-emitting element that emits colored light, it exhibits high luminous efficiency, and in particular, the maximum value of the external quantum efficiency This shows a high value of 6.9%. In addition, in the light-emitting element 8, the roll in the high-brightness region The off-state is also suppressed. This is an excellent feature that can only be achieved with ExSET, which is one aspect of the present invention. This is the effect.

[0441] As described above, by using ExSET, the light-emitting element of one embodiment of the present invention has high luminescence effect It was confirmed that it has a rate.

[0442] The configuration shown in this embodiment can be used in appropriate combination with other embodiments and models. It is possible. [Explanation of symbols]

[0443] 100 EL layer 101 Electrode 102 electrode 111 Hole injection layer 112 Hole transport layer 113 Emitting layer 115 Electron transport layer 116 Electron injection layer 121 Host Materials 121_1 Organic compounds 121_2 Organic compounds 122 Guest Materials 150 light-emitting elements 401 Electrode 402 Electrode 411 Hole injection layer 412 Hole transport layer 413 Electron transport layer 414 Electron injection layer 415 Hole injection layer 416 Hole transport layer 417 Electron transport layer 418 Electron injection layer 421 Host Materials 421_1 Organic compounds 421_2 Organic compounds 422 Guest Materials 431 Host Materials 431_1 Organic compounds 431_2 Organic compounds 432 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 elements 452 Light-emitting element 461 Host Materials 462 Guest Materials 471 Host Materials 471_1 Organic compounds 471_2 Organic compounds 472 Guest Materials 801 Pixel Circuit 802 pixel section 804 Drive Circuit Section 804a Scan line drive circuit 804b Signal line drive circuit 806 protection circuit 807 Terminal section 852 transistors 854 transistors 862 Capacitive elements 872 Light-emitting element 1100 circuit board 1101 Electrode 1102 Electrode 1111 Hole injection layer 1112 Hole transport layer 1113 Emitting layer 1115 Electron transport layer 1116 Electron injection layer 1150 Sealing substrate 2000 Touch Panel 2001 Touch Panel 2501 Display device 2502R pixels 2502t Transistor 2503c Capacitive element 2503g Scan line drive circuit 2503s Signal Line Drive Circuit 2503t Transistor 2509 FPC 2510 circuit 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 circuit board 2570a Insulating layer 2570b flexible substrate 2570c adhesive layer 2580R Light-Emitting Module 2590 circuit board 2591 Electrode 2592 Electrode 2593 Insulating layer 2594 Wiring 2595 Touch Sensor 2597 Adhesive layer 2598 Wiring 2599 Connectivity Layer 2601 Pulse voltage output circuit 2602 Current detection circuit 2603 Capacity 2611 Transistors 2612 transistors 2613 Transistors 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 device 8502 Lighting device 8503 Lighting device 8504 Lighting device 9000 cabinets 9001 Display section 9003 Speaker 9005 Operation Keys 9006 Connection terminal 9007 Sensor 9008 Microphone 9050 Operation Buttons 9051 Information 9052 Information 9053 Information 9054 Information 9055 Hinge 9100 Mobile Information Terminal 9101 Mobile Information Terminal 9102 Mobile Information Terminal 9200 Mobile Information Terminal 9201 Mobile Information Terminal

Claims

[Claim 1] A pair of electrodes, The pair of electrodes has an EL layer provided between them, The EL layer has a light-emitting layer, The light-emitting layer comprises a host material and a guest material. The aforementioned host material is The difference between the singlet excitation energy level and the triplet excitation energy level is greater than 0 eV and less than or equal to 0.2 eV. The aforementioned guest material has the function of emitting fluorescence, The triplet excitation energy levels of the host material are A light-emitting element with an excitation energy level higher than the triplet excitation energy level of the aforementioned guest material.

Images