Organic light-emitting element

Abstract

The present disclosure provides an organic light-emitting element in which: a first light-emitting layer includes a first organic compound, a first light-emitting material, and a second light-emitting material; and the second light-emitting layer includes a second organic compound and a third light-emitting material. In the organic light-emitting element, the difference in HOMO energy levels between the first light-emitting material and the first organic compound in the first light-emitting layer is made smaller than the difference in LUMO energy levels between the second organic compound and the third light-emitting material in the second light-emitting layer, and the content of the light-emitting material in the first light-emitting layer is reduced. The hole capture capability in the first light-emitting layer is mitigated such that the recombination region of holes and electrons is away from the electrode side of the first light-emitting layer and is localized in the light-emitting layer at the same time.

Description

Technical Field

[0001] The present invention relates to an organic light-emitting element and various equipment and devices including the organic light-emitting element. Background Art

[0002] An organic light-emitting element (also referred to as an "organic electroluminescent element" or "organic EL element" in some cases) is an element that includes an anode, a cathode, and an organic compound layer disposed between these electrodes and including a light-emitting layer, and emits light by energizing the organic compound layer. Compared to known display devices, organic light-emitting elements are used in various display devices due to their high degree of freedom in shape, light weight, and high color rendering properties. As one of the technologies, a full-color display using an organic light-emitting element is known. Its system includes a system that emits light with different colors by creating a light-emitting layer for each pixel (element) and a system that includes a light-emitting layer for emitting white light and extracting a light-emitting layer with different colors for each pixel using a color filter. Regarding the white light-emitting layer, it is known to use two or more light-emitting materials and to use a light-emitting layer composed of two or more layers.

[0003] In recent years, development of products for further application has been actively pursued, and in particular, technology for improving the driving durability of organic white light-emitting elements has been required.

[0004] PTL 1 describes an organic light-emitting element including two stacked light-emitting layers, wherein the light-emitting layer on the cathode side contains 0.6 mass % of a blue light-emitting dopant, and the light-emitting layer on the anode side contains a red light-emitting dopant and 2.0 mass % of a green light-emitting dopant.

[0005] Prior art literature

[0006] Patent Literature

[0007] PTL 1: Japanese Patent Laid-Open No. 2019-186521 Summary of the Invention

[0008] Problems to be solved by the invention

[0009] PTL 1 describes the configuration of a white organic light-emitting element including blue, green, and red light-emitting dopants, but there is room for improving the concentration of the light-emitting dopants in the light-emitting layer and the resulting charge balance.

[0010] Solutions for solving problems

[0011] In view of the above problems, the present invention aims to improve light-emitting characteristics and driving durability characteristics in an organic light-emitting element including two light-emitting layers.

[0012] The first organic light-emitting element of the present invention is an organic light-emitting element comprising a first electrode, a first light-emitting layer, a second light-emitting layer, and a second electrode in sequence, wherein the first light-emitting layer comprises a first organic compound, a first light-emitting material, and a second light-emitting material, and the second light-emitting layer comprises a second organic compound and a third light-emitting material, and satisfies the following formulas [1] to [4]:

[0013] [1](HOMOd2-HOMOh1)<(LUMOh2-LUMOd3);

[0014] [2] The content of the first luminescent material is less than the content of the second luminescent material;

[0015] [3] the content of the first luminescent material is less than the content of the third luminescent material; and

[0016] [4] The content of the second luminescent material is less than 2.0% by mass.

[0017] HOMOh1: HOMO level of the first organic compound;

[0018] HOMOd2: HOMO energy level of the second luminescent material;

[0019] LUMOh2: LUMO energy level of the second organic compound; and LUMOd3: LUMO energy level of the third light-emitting material.

[0020] The second organic light-emitting element of the present invention includes a first electrode, a first light-emitting layer, a second light-emitting layer, an adjacent layer, and a second electrode in sequence, wherein the first light-emitting layer includes a first organic compound, a first light-emitting material, and a second light-emitting material, the second light-emitting layer includes a second organic compound and a third light-emitting material, and the adjacent layer is made of an organic compound composed of a hydrocarbon, and satisfies the following formula [4]:

[0021] [4] The content of the second luminescent material is less than 2.0% by mass.

[0022] Effects of the Invention

[0023] According to the present invention, in an organic light-emitting element including two or more light-emitting layers, light-emitting characteristics and driving durability characteristics can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] [ Figure 1A ] is a schematic cross-sectional view showing an example of a pixel of a display device according to an embodiment of the present invention.

[0025] [ Figure 1B ] is a schematic cross-sectional view of an example of a display device using an organic light-emitting element according to an embodiment of the present invention.

[0026] [ Figure 2] is a schematic diagram showing an example of a display device according to an embodiment of the present invention.

[0027] [ Figure 3A ] is a schematic diagram of an imaging device according to an embodiment of the present invention.

[0028] [ Figure 3B ] is a schematic diagram of an electronic device according to an embodiment of the present invention.

[0029] [ Figure 4A ] is a schematic diagram of a display device according to an embodiment of the present invention.

[0030] [ Figure 4B ] is a schematic diagram of a foldable display device according to one embodiment of the present invention.

[0031] [ Figure 5A ] is a schematic diagram of a lighting device according to an embodiment of the present invention.

[0032] [ Figure 5B ] is a schematic diagram of a car having a vehicle lighting device according to one embodiment of the present invention.

[0033] [ Figure 6A ] is a schematic diagram of a wearable device according to one embodiment of the present invention. [ Figure 6B ] is a schematic diagram showing an example of a wearable device in the form of a camera according to one embodiment of the present invention.

[0034] [ Figure 7A ] is a schematic diagram of an image forming apparatus according to an embodiment of the present invention.

[0035] [ Figure 7B ] is a schematic diagram showing a structure in which multiple light-emitting portions of an exposure light source are arranged on a long-sized substrate.

[0036] [ Figure 7C ] is a schematic diagram showing a structure in which multiple light-emitting portions of an exposure light source are arranged on a long-sized substrate. DETAILED DESCRIPTION

[0037] The first organic light-emitting element of the present invention includes a first electrode, a first light-emitting layer, a second light-emitting layer, and a second electrode in sequence, wherein the first light-emitting layer includes a first organic compound, a first light-emitting material, and a second light-emitting material, and the second light-emitting layer includes a second organic compound and a third light-emitting material, and satisfies the following formulas [1] to [4]:

[0038] [1](HOMOd2-HOMOh1)<(LUMOh2-LUMOd3);

[0039] [2] The content of the first luminescent material is less than the content of the second luminescent material;

[0040] [3] the content of the first luminescent material is less than the content of the third luminescent material; and

[0041] [4] The content of the second luminescent material is less than 2.0% by mass.

[0042] HOMOh1: HOMO level of the first organic compound;

[0043] HOMOd2: HOMO energy level of the second luminescent material;

[0044] LUMOh2: LUMO energy level of the second organic compound; and LUMOd3: LUMO energy level of the third light-emitting material.

[0045] The characteristics of the light-emitting layer of the organic light-emitting element of the present invention will now be described.

[0046] To improve the luminescence characteristics and driving durability of organic light-emitting elements, it is necessary to confine both injected holes and electrons within the light-emitting layer and effectively recombine them. Specifically, it is necessary to reduce the leakage of holes from the light-emitting layer to the cathode-side layers and the leakage of electrons from the light-emitting layer to the anode-side layers. Furthermore, it is desirable to improve the durability of the delocalized charge recombination region within the light-emitting layer. This reduces the excitation load per molecule and suppresses the degradation of the excited state.

[0047] To confine holes and electrons in the light-emitting layer, an electron-blocking layer on the anode side of the light-emitting layer and a hole-blocking layer on the cathode side are effective. Examples of materials for the electron-blocking layer include arylamine derivatives with highly electron-donating nitrogen-containing backbones. While these derivatives have high hole-transporting capabilities, they suffer from low radical anion stability. Therefore, it has been demonstrated that by keeping the recombination zone away from the interface between the light-emitting layer and the electron-blocking layer, thereby suppressing electron transport at the interface or excitation through recombination, the durability of the organic light-emitting element is improved.

[0048] Therefore, in the present invention, holes are efficiently trapped in the first emitting layer and electrons are efficiently trapped in the second emitting layer, thereby confining charge in both emitting layers and simultaneously delocalizing the recombination zone. Furthermore, by reducing the content of the luminescent material in the first emitting layer, the hole-trapping capacity of the first emitting layer is moderated. Even when layers including an arylamine derivative, such as an electron-blocking layer and a hole-injection layer, are provided on the first electrode side of the first emitting layer, degradation of these layers is suppressed by keeping the recombination zone away from the first electrode-side interface of the first emitting layer. Consequently, the durability characteristics of the organic light-emitting element are improved.

[0049] The expression [1] that is a characteristic of the present invention shows that the hole capture ability of the first light-emitting layer is lower than the electron capture ability of the second light-emitting layer. The HOMO energy level of the light-emitting material of the light-emitting layer is shallower (closer to vacuum) than the HOMO energy level of the host material, but the greater the difference therebetween, the higher the hole capture ability of the light-emitting layer. In addition, the LUMO energy level of the light-emitting material of the light-emitting layer is deeper (farther away from vacuum level) than the LUMO energy level of the host material, but the greater the difference therebetween, the higher the electron capture ability of the light-emitting layer. Therefore, by making the difference in HOMO energy level between the second light-emitting material and the first organic compound in the first light-emitting layer smaller than the difference in LUMO energy level between the third light-emitting material and the second organic compound in the second light-emitting layer, the hole capture ability of the first light-emitting layer becomes lower than the electron capture ability of the second light-emitting layer. That is, by using the first electrode on the first light-emitting layer side as an anode, the recombination region is retracted from the first electrode side of the first light-emitting layer.

[0050] Here, HOMO means highest occupied molecular orbital, and LUMO means lowest unoccupied molecular orbital. The energy level of HOMO is also referred to as "HOMO" or "HOMO level," and the energy level of LUMO is also referred to as "LUMO" or "LUMO level."

[0051] Expressions [2] to [4], which are characteristic features of the present invention, indicate that the content of the light-emitting material in the first light-emitting layer is small. Specifically, as shown in expressions [2] and [3], the content of the first light-emitting material is smaller than the content of the second and third light-emitting materials. Furthermore, as shown in expression [4], the content of the second light-emitting material is suppressed to be less than 2.0% by mass. Therefore, the hole-trapping ability of the first light-emitting layer is suppressed to be lower than the electron-trapping ability of the second light-emitting layer, and the recombination region is located closer to the second light-emitting layer.

[0052] Furthermore, preferred conditions in the present invention are described.

[0053] In the present invention, it is preferred to control the content of the third light-emitting material in the second light-emitting layer to be 1.0 mass % or more, because the electron capture ability of the second light-emitting layer is increased, and the recombination region is located closer to the second light-emitting layer and can be kept away from the first electrode side interface of the first light-emitting layer.

[0054] The first light-emitting material preferably emits red light, and the content of the first light-emitting material in the first light-emitting layer is preferably less than 0.3% by mass and more preferably less than 0.2% by mass. A reduced content of the first light-emitting material is preferred because it suppresses exciton loss due to concentration vanishing and improves luminous efficiency. When the first light-emitting material emits red light, an organic light-emitting element emitting white light can be obtained by using one of the second and third light-emitting materials as a blue light-emitting material and the other as a green light-emitting material, but the present invention is not necessarily limited to this configuration.

[0055] Regarding the thickness of the light-emitting layer, the thickness of the first light-emitting layer is preferably greater than that of the second light-emitting layer. This is because, as described above, a greater thickness of the first light-emitting layer is effective in positioning the recombination region closer to the second light-emitting layer and delocalizing the recombination region by keeping the recombination region away from the interface on the first electrode side of the first light-emitting layer.

[0056] The first organic compound and the second organic compound are preferably the same organic compound because the absence of an energy barrier between the first light-emitting layer and the second light-emitting layer is preferable for delocalization of the recombination region.

[0057] The first light-emitting material, the second light-emitting material and the third light-emitting material are not particularly limited as long as they each satisfy the energy relationship of the above expression [1], but the material preferably has a fluoranthene skeleton. Since the fluoranthene skeleton is electron-deficient, the LUMO energy level is deep. Therefore, this material is suitable for the organic light-emitting element of the present invention. Examples of the light-emitting materials according to the present invention are shown below, but are not limited thereto. The following R-1 to R-27 are examples of the first light-emitting material, G-1 to G-24 are examples of the second light-emitting material, and B-1 to B-62 are examples of the third light-emitting material. In the present invention, the first light-emitting material is preferably a red light-emitting material, the second light-emitting material is preferably a green light-emitting material, and the third light-emitting material is preferably a blue light-emitting material.

[0058] [Chemical Formula 1]

[0059]

[0060] [Chemical Formula 2]

[0061]

[0062] [Chemical Formula 3]

[0063]

[0064] [Chemical Formula 4]

[0065]

[0066] [Chemical Formula 5]

[0067]

[0068] The first organic compound and the second organic compound are not particularly limited as long as they each satisfy the energy relationship of the above expression [1], but the material preferably has a pyrene skeleton. The pyrene skeleton is preferred because it has high planarity, which is advantageous for controlling charge transport, and also has an energy level that can be applied to all blue, green, and red light-emitting materials.

[0069] In both the first and second organic compounds, for good durability characteristics, all freely rotatable single bonds are preferably carbon-carbon bonds, and at least one carbon in the carbon-carbon bond is further preferably sp 2 carbon.

[0070] The light-emitting layer generally includes a host material and a light-emitting dopant material. The first organic compound and the second organic compound according to the present invention are host materials, and the first light-emitting material, the second light-emitting material and the third light-emitting material are light-emitting dopant materials. The host material is the compound with the largest mass ratio among the compounds constituting the light-emitting layer. The light-emitting dopant is a compound with a mass ratio less than that of the host material among the compounds constituting the light-emitting layer, and is the main compound that emits light. In addition to the host material and the light-emitting dopant material, the light-emitting layer may contain an auxiliary material. The auxiliary material is a compound with a mass ratio less than that of the host material and greater than that of the light-emitting dopant material among the compounds constituting the light-emitting layer. That is, the mass ratio is (host material)>(auxiliary material)>(light-emitting dopant material). The light-emitting dopant material is also called a guest.

[0071] The contents of the first and second light-emitting materials in the first light-emitting layer and the third light-emitting material in the second light-emitting layer according to the present invention may be any contents as long as they satisfy the above-mentioned expressions [2] to [4].

[0072] As long as the effects of the present invention can be achieved, the light-emitting material may be contained uniformly or with a concentration gradient throughout the first light-emitting layer or the second light-emitting layer in which the first organic compound or the second organic compound forms a matrix. The light-emitting layer may be a layer that partially includes the light-emitting material in a specific region of the layer, including a region where only the matrix is ​​present and no light-emitting material is included.

[0073] Within the scope of the effects of the present invention, the first light-emitting layer, the second light-emitting layer or the third light-emitting layer required to be set according to the present invention may include materials other than the above-mentioned first organic compound, the second organic compound, the first light-emitting material, the second light-emitting material and the third light-emitting material.

[0074] Examples of luminescent materials primarily related to luminescent functions include, in addition to the above-mentioned luminescent materials, fused ring compounds (e.g., fluorene derivatives, naphthalene derivatives, pyrene derivatives, perylene derivatives, tetracene derivatives, anthracene derivatives, and rubrene), quinacridone derivatives, coumarin derivatives, stilbene derivatives, organic aluminum complexes such as tris(8-hydroxyquinoline)aluminum, iridium complexes, platinum complexes, rhenium complexes, copper complexes, europium complexes, ruthenium complexes, and polymer derivatives such as poly(phenylene vinylene) derivatives, poly(fluorene) derivatives, and poly(phenylene) derivatives. Examples of compounds used as luminescent materials are specifically shown below, but are not limited thereto.

[0075] [Chemical Formula 6]

[0076]

[0077] [Chemical Formula 7]

[0078]

[0079] The first and second light-emitting layers may include a third organic compound in addition to the first and second organic compounds as a host material or an auxiliary material. Examples of the third organic compound include, but are not limited to, aromatic hydrocarbon compounds and their derivatives, carbazole derivatives, azine derivatives, xanthone derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, organoaluminum complexes such as tris(8-hydroxyquinolinol)aluminum, and organoberyllium complexes. Specific examples are shown below.

[0080] [Chemical Formula 8]

[0081]

[0082] The organic light emitting element of the present invention includes a first electrode, a second electrode and an organic compound layer between the first electrode and the second electrode, and the organic compound layer includes at least a first light emitting layer and a second light emitting layer. In the present invention, the functional layer can be appropriately arranged between the first electrode and the first light emitting layer and between the second light emitting layer and the second electrode. Examples of the functional layer, in addition to the light emitting layer, also include a hole injection layer, a hole transport layer, an electron blocking layer, a hole / exciton blocking layer, an electron transport layer and an electron injection layer. In addition, a light emitting layer other than the first light emitting layer and the second light emitting layer according to the present invention can be provided.

[0083] In the present invention, an adjacent layer may be provided adjacent to the cathode side of the second light-emitting layer, and the adjacent layer is preferably made of an organic compound composed of hydrocarbons. The reason for this will be described.

[0084] As described above, the recombination region of the organic light-emitting layer of the present invention is closer to the second light-emitting layer. Therefore, the adjacent layer adjacent to the second light-emitting layer is located in a region with a large amount of charges and excitons, and is prone to degradation of the organic compound. Therefore, the adjacent layer according to the present invention is preferably made of an organic compound composed of hydrocarbons with high binding stability and chemical stability. Examples include, for example, the aforementioned EM1 to EM12 and EM16 to EM27 compounds, but are not limited thereto, as long as the compound is composed of hydrocarbons.

[0085] Organic compounds composed of hydrocarbons preferably have a fused polycyclic backbone with four or more rings. This large number of fused rings provides the following benefits: First, it reduces the band gap, thereby lowering the voltage in organic light-emitting devices. Second, it improves thermal stability, such as the glass transition temperature. Third, it increases planarity, thereby improving electron mobility and lowering the voltage in organic light-emitting devices.

[0086] The organic compound composed of hydrocarbons is preferably composed entirely of sp 2 This is because sp 2 The binding energy between carbon atoms is higher than that of sp 3 The binding energy between carbon atoms is increased, thus obtaining a molecular structure with higher binding stability.

[0087] The second organic light-emitting element of the present invention includes a first electrode, a first light-emitting layer, a second light-emitting layer, an adjacent layer, and a second electrode in sequence, wherein the first light-emitting layer includes a first organic compound, a first light-emitting material, and a second light-emitting material, the second light-emitting layer includes a second organic compound and a third light-emitting material, and the adjacent layer is made of an organic compound composed of hydrocarbons, and satisfies the following expression [4]:

[0088] [4] The content of the second luminescent material is less than 2.0% by mass.

[0089] The inventors have found that it is preferred that the content of the second light-emitting material in the organic light-emitting element of the present invention is less than 2.0 mass%. This is due to the following two reasons. The first is that concentration quenching occurs when the content of the second light-emitting material of the present invention is 2.0 mass% or more, and for high efficiency, a content of less than 2.0 mass% is preferred. Further preferably, the second light-emitting material is an organic compound composed of hydrocarbons. When the compound is composed only of hydrocarbons, planarity increases and concentration quenching becomes more significant. The second is that the hole capture ability of the first light-emitting layer is suppressed by keeping the content of the second light-emitting material less than 2.0 mass%, and the recombination region is located closer to the second light-emitting layer side. As a result, the recombination region reaches the interface between the second light-emitting layer and the adjacent layer. Therefore, the structural stability of the adjacent layer affects the characteristics. That is, the organic compound constituting the adjacent layer is preferably made of hydrocarbons with high binding stability.

[0090] It was found that a light-emitting layer configuration can achieve both high efficiency and high durability characteristics by virtue of the above two factors.

[0091] The charge generation layer can be positioned between the first light-emitting layer and the first electrode, and between the second light-emitting layer and the second electrode. The charge generation layer functions as a tandem element, where electrons generated in the charge generation layer and holes injected from the first electrode recombine to form excitons, and holes generated in the charge generation layer and electrons injected from the second electrode recombine to form excitons. This doubles the internal quantum efficiency. Film formation is also performed by evaporation or coating.

[0092] Examples of the element configuration of the organic light-emitting element of this embodiment include a multilayer element configuration in which the electrode layers and organic compound layers shown below (1) to (6) are sequentially stacked on a substrate. In each element configuration, the organic compound layer necessarily includes a light-emitting layer containing a light-emitting material. The "light-emitting layer" below includes the first light-emitting layer and the second light-emitting layer according to the present invention, such that the first light-emitting layer is on the anode side and the second light-emitting layer is on the cathode side.

[0093] (1) anode / luminescent layer / cathode;

[0094] (2) anode / hole transport layer / luminescent layer / electron transport layer / cathode;

[0095] (3) anode / hole transport layer / luminescent layer / electron transport layer / electron injection layer / cathode;

[0096] (4) anode / hole injection layer / hole transport layer / light-emitting layer / electron transport layer / cathode;

[0097] (5) anode / hole injection layer / hole transport layer / light-emitting layer / electron transport layer / electron injection layer / cathode; and

[0098] (6) Anode / hole transport layer / electron blocking layer / light-emitting layer / hole blocking layer / electron transport layer / cathode.

[0099] However, these element configuration examples are merely basic element configurations and are not limited thereto. For example, various layer configurations may be employed, such as a configuration in which an insulating layer, an adhesive layer, or an interference layer is provided at the interface between the electrode and the organic compound layer, or a configuration in which an electron transport layer or a hole transport layer is composed of two layers having different ionization potentials.

[0100] Among the element configurations shown in (1) to (6) above, configuration (6) is preferred because it includes both an electron blocking layer and a hole blocking layer. That is, in configuration (6) including both an electron blocking layer and a hole blocking layer, since both hole and electron carriers can be reliably confined in the light-emitting layer, an organic light-emitting element having high luminous efficiency without causing carrier leakage is obtained.

[0101] The compounds of the electron blocking layer and the hole blocking layer in contact with the light-emitting layer preferably have a stable structure. For example, since the hole blocking layer needs to be stable against holes, the hole blocking layer compound is preferably an organic compound with low reactivity, and more preferably an organic compound composed only of hydrocarbons. Since the electron blocking layer also needs to be stable against electrons, it is preferably an organic compound with low reactivity, and more preferably all carbon-carbon bonds are freely rotatable single bonds, preferably sp 2 Carbon-sp 2 Carbon-bonded organic compounds.

[0102] The method (element form) for extracting light emitted from the light-emitting layer can be a so-called bottom emission system that extracts light from the electrode on the substrate side, or a so-called top emission system that extracts light from the other side of the substrate. Alternatively, a dual-side emission system that extracts light from both the substrate side and the other side of the substrate can be used.

[0103] The organic compound layer is mainly composed of an organic compound, but may include inorganic atoms or inorganic compounds such as copper, lithium, magnesium, aluminum, iridium, platinum, molybdenum, and zinc.

[0104] The organic compound layer can be formed using dry processes such as vacuum evaporation, ionization evaporation, sputtering, and plasma methods. Instead of a dry process, a wet process (e.g., spin coating, dipping, casting, LB method, and inkjet method) of forming a layer by dissolving in a suitable solvent may be used.

[0105] Here, when the layer is formed by vacuum deposition or solution coating, crystallization is unlikely to occur and the stability over time is excellent. When the layer is formed by coating, it can also be formed into a film by combining with an appropriate binder resin.

[0106] Examples of the binder resin include, but are not limited to, polyvinyl carbazole resin, polycarbonate resin, polyester resin, ABS resin, acrylic resin, polyimide resin, phenolic resin, epoxy resin, silicone resin, and urea resin.

[0107] These binder resins may be used alone as a homopolymer or a copolymer, or may be used as a mixture of two or more thereof. In addition, known additives such as a plasticizer, an antioxidant, and a UV absorber may be used in combination as needed.

[0108] In the present invention, in layers other than the light-emitting layer, known low-molecular-weight and high-molecular-weight hole-injecting or hole-transporting compounds and electron-injecting or electron-transporting compounds can be used as needed. Specific examples thereof are given below.

[0109] The hole injection / transport material is preferably a material that facilitates hole injection from the anode and has a high hole mobility to transport the injected holes to the light-emitting layer. In addition, a material with a high glass transition temperature is preferably used to suppress the degradation of film quality such as crystallization in the organic light-emitting element. Examples of low-molecular-weight and high-molecular-weight materials with hole injection / transport performance include triarylamine derivatives, arylcarbazole derivatives, phenylenediamine derivatives, stilbene derivatives, phthalocyanine derivatives, porphyrin derivatives, poly (vinylcarbazole), poly (thiophene) and other conductive polymers. In addition, the hole injection / transport material is also suitably used in the electron blocking layer. Examples of compounds used as hole injection / transport materials are specifically shown below, but are not limited thereto.

[0110] [Chemical Formula 9]

[0111]

[0112] The electron transport material can be arbitrarily selected from materials that can transport electrons injected from the cathode to the light-emitting layer, and is selected in consideration of, for example, the balance of hole mobility of the hole transport material. Examples of materials having electron transporting properties include oxadiazole derivatives, oxazole derivatives, pyrazine derivatives, triazole derivatives, triazine derivatives, quinoline derivatives, quinoxaline derivatives, phenanthroline derivatives, organoaluminum complexes, fused ring compounds (e.g., fluorene derivatives, naphthalene derivatives, Derivatives and anthracene derivatives). In addition, the above-mentioned electron transporting materials are also suitably used in the hole blocking layer. Examples of compounds used as electron transporting materials are specifically shown below, but are not limited thereto. Examples are as follows.

[0113] [Chemical Formula 10]

[0114]

[0115] The electron-injecting material can be arbitrarily selected from materials that can easily inject electrons from the cathode, and is selected in consideration of, for example, the balance of hole injection properties. Organic compounds also include n-type dopants and reductive dopants, and examples thereof include alkali metal-containing compounds such as lithium fluoride, lithium complexes such as lithium quinoline, benzimidazolidine derivatives, imidazolidine derivatives, fullerene derivatives, and acridine derivatives. It can also be used in combination with the above-mentioned electron transporting materials.

[0116] [Other Configurations of Organic Light-Emitting Element]

[0117] An organic light-emitting element is typically constructed by forming an insulating layer, a first electrode, an organic compound layer, and a second electrode on a substrate. A protective layer, color filter, or microlens, etc., may be provided on the second electrode. When a color filter is provided, a planarization layer may be provided between the color filter and the protective layer. The planarization layer can be made of, for example, an acrylic resin. The same applies when the planarization layer is provided between the color filter and the microlens.

[0118] A preferred configuration of the organic light-emitting element of the present invention excluding the organic compound layer will be described below.

[0119] [Substrate]

[0120] The organic light-emitting element of the present invention can be formed on a substrate. Examples of substrates include quartz, glass, silicon wafers, resins, and metals. On the substrate, switching elements such as transistors and wiring are provided, and an insulating layer can be provided thereon. The insulating layer can be made of any material that can be formed with contact holes, so that wiring to the first electrode can be formed and insulation from unconnected wiring can be ensured. For example, a resin such as polyimide, silicon oxide, or silicon nitride can be used.

[0121] [electrode]

[0122] In the present invention, one of the first and second electrodes is an anode, and the other is a cathode. When an electric field is applied in the direction of light emission from the organic light-emitting element, the electrode with a higher potential becomes the anode, and the electrode with a lower potential becomes the cathode. Alternatively, the electrode that provides holes to the light-emitting layer is the anode, and the electrode that provides electrons is the cathode.

[0123] The anode is preferably made of a material having as large a work function as possible. For example, metal elements such as gold, platinum, silver, copper, nickel, palladium, cobalt, selenium, vanadium, and tungsten, mixtures thereof, or alloys thereof, or metal oxides such as tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide can be used. Conductive polymers such as polyaniline, polypyrrole, or polythiophene can also be used.

[0124] These electrode materials may be used alone or in combination of two or more. The anode may be composed of a single layer or a plurality of layers.

[0125] When used as a reflective electrode, materials such as chromium, aluminum, silver, titanium, tungsten, molybdenum, or alloys or stacks thereof can be used. These materials can also function as a reflective film without acting as an electrode. When used as a transparent electrode, transparent conductive layers of oxides such as indium tin oxide (ITO) and indium zinc oxide can be used, but are not limited to these. Electrodes can be formed using photolithography.

[0126] In contrast, the cathode is preferably made of a material having a small work function. Examples include alkali metals such as lithium, alkaline earth metals such as calcium, metal elements such as aluminum, titanium, manganese, silver, lead and chromium, and mixtures thereof. Alternatively, alloys of combinations of these metal elements may also be used. For example, magnesium-silver, aluminum-lithium, aluminum-magnesium, silver-copper and zinc-silver may be used. Metal oxides such as indium tin oxide (ITO) may also be used. These electrode materials may be used alone or in combination of two or more. The cathode may consist of one layer or may consist of multiple layers. In particular, silver is preferably used, and a silver alloy is further preferred in order to reduce the aggregation of silver. The alloy ratio is not important as long as the aggregation of silver can be reduced. For example, the ratio of silver to another metal may be 1:1 or 3:1, etc.

[0127] The cathode is not particularly limited, and an oxide conductive layer of ITO or the like can be used to form a top-emitting element, or a reflective electrode of aluminum (Al) or the like can be used to form a bottom-emitting element. The method for forming the cathode is not particularly limited, but DC and AC sputtering methods are preferred because of their high film coverage and ease of reducing resistance.

[0128] [Protective layer]

[0129] A protective layer can be provided on the second electrode. For example, by bonding a glass provided with a moisture absorbent to the second electrode, the infiltration of water and the like into the organic compound layer can be reduced, thereby reducing the occurrence of poor display. In another embodiment, the infiltration of water and the like into the organic compound layer can be reduced by providing a passivation film of silicon nitride and the like on the second electrode. For example, a second electrode is formed and then transferred to another chamber without destroying the vacuum, and a silicon nitride film with a thickness of 2 μm can be formed as a protective layer by a CVD method. After the film is formed by the CVD method, an atomic layer evaporation method (ALD method) can be used to form a protective layer. The film material by the ALD method is not limited, but can be silicon nitride, silicon oxide or aluminum oxide and the like. On the film formed by the ALD method, a silicon nitride film can be further formed by the CVD method. The thickness of the film by the ALD method can be less than the thickness of the film formed by the CVD method. Specifically, the thickness by the ALD method can be less than 50% or less than 10% of the thickness by the CVD method.

[0130] [Color Filter]

[0131] The color filter can be placed on the protective layer. For example, depending on the size of the organic light-emitting element, the color filter can be placed on a separate substrate, and this substrate and the substrate with the organic light-emitting element can be attached together. Alternatively, the color filter can be patterned on the protective layer using photolithography. The color filter can be made of a polymer.

[0132] [Planarization layer]

[0133] A planarization layer can be provided between the color filter and the protective layer. The purpose of providing a planarization layer is to reduce the unevenness of the underlying layer. The planarization layer can also be referred to as a resin layer, without any limitation on its purpose. The planarization layer can be made of an organic compound, which can be a low-molecular-weight or high-molecular-weight compound, preferably a high-molecular-weight compound.

[0134] The planarization layer can be provided above and below the color filter, and its constituent materials can be the same or different. Examples of the material include polyvinyl carbazole resin, polycarbonate resin, polyester resin, ABS resin, acrylic resin, polyimide resin, phenolic resin, epoxy resin, silicone resin, and urea resin.

[0135] [Microlens]

[0136] An organic light-emitting element or a light-emitting device including an organic light-emitting element may include an optical component, such as a microlens, on the light-emitting side. The microlens may be made of an acrylic resin, an epoxy resin, or the like. The purpose of the microlens may be to increase the amount of light extracted from the organic light-emitting element or the light-emitting device, or to control the direction of the extracted light. The microlens may have a hemispherical shape. When the microlens has a hemispherical shape, the tangent line in contact with the hemisphere includes a tangent line parallel to the insulating layer, and the point of contact between the tangent line and the hemisphere is the vertex of the microlens. The vertex of the microlens can also be similarly determined in any cross-sectional view. That is, the tangent line in contact with the hemisphere of the microlens in the cross-sectional view includes a tangent line parallel to the insulating layer, and the point of contact between the tangent line and the hemisphere is the vertex of the microlens.

[0137] The midpoint of a microlens can also be defined. In a cross-section of a microlens, imagine a line segment from a point where the shape of a circular arc ends to a point where the shape of another circular arc ends. The midpoint of this line segment can be called the midpoint of the microlens. The cross-section that determines the vertex or midpoint can be a cross-section perpendicular to the insulating layer.

[0138] [Countering substrate]

[0139] The counter substrate can be disposed on the planarization layer. Since the counter substrate is disposed at a position corresponding to the aforementioned substrate, it is referred to as the counter substrate. The counter substrate can be made of the same material as the aforementioned substrate. When the aforementioned substrate is referred to as the first substrate, the counter substrate is referred to as the second substrate.

[0140] [Pixel circuit]

[0141] A light-emitting device including an organic light-emitting element may include a pixel circuit connected to the organic light-emitting element. The pixel circuit may be an active matrix type that independently controls the light emission of each of the multiple organic light-emitting elements. The active matrix type circuit may be a voltage-programmed circuit or a current-programmed circuit. A driving circuit includes a pixel circuit for each pixel. The pixel circuit may include a transistor for controlling the organic light-emitting element and the brightness of the organic light-emitting element, a transistor for controlling the timing of light emission, and a transistor for connecting a capacitor for maintaining the gate voltage of the transistor to control the brightness of the light emission to ground when no light-emitting element is involved.

[0142] The light-emitting device includes a display area and a peripheral area configured around the display area. The display area includes a pixel circuit, and the peripheral area includes a display control circuit. The mobility of the transistor constituting the pixel circuit can be less than the mobility of the transistor constituting the display control circuit. The slope of the current-voltage characteristic of the transistor constituting the pixel circuit can be less than the slope of the current-voltage characteristic of the transistor constituting the display control circuit. The slope of the current-voltage characteristic can be measured by the so-called Vg-Ig characteristic. The transistor constituting the pixel circuit is a transistor connected to the organic light-emitting element.

[0143] [Pixels]

[0144] A light-emitting device including an organic light-emitting element may include a plurality of pixels. Each pixel includes sub-pixels that emit light of different colors. The sub-pixels may each have an emission color, such as RGB.

[0145] The pixel emits light from an area also referred to as the pixel opening. The pixel opening can be 15 μm or less, and can be 5 μm or more, more specifically, can be, for example, 11 μm, 9.5 μm, 7.4 μm, or 6.4 μm. The distance between sub-pixels can be 10 μm or less, and more specifically, 8 μm, 7.4 μm, or 6.4 μm.

[0146] The pixels can adopt a known configuration in a plan view, such as a stripe configuration, a delta configuration, a pentile configuration, or a Bayer configuration. The shape of the sub-pixels in the plan view can be any known shape, such as a quadrilateral, a rectangle, a rhombus, or a hexagon. If the shape is not exact, but is close to a rectangle, it is of course included in the rectangle. The shapes of the sub-pixels and pixel arrangements can be used in combination.

[0147] [Applications of organic light-emitting devices]

[0148] The organic light emitting element of the present invention can be used as a component of a display device or a lighting device. In addition, there are applications such as exposure light sources of electrophotographic image forming devices, backlights of liquid crystal display devices, and light emitting devices including color filters in white light sources.

[0149] The display device may be an image information processing device that includes an image input unit for inputting image information from an area CCD, a linear CCD, a memory card, or the like, an information processing unit for processing the input information, and displays the input image on a display unit. The display device includes a plurality of pixels, at least one of which includes the organic light-emitting element of the present invention, and may further include a transistor connected to the organic light-emitting element.

[0150] The display unit of an imaging device or inkjet printer may have a touch panel function. The driving system of the touch panel function may be an infrared system, an electrostatic capacitance system, a resistive film system, or an electromagnetic induction system, and is not particularly limited. The display device may also be used in the display unit of a multifunction printer.

[0151] Next, the display device according to the present embodiment will be described with reference to the drawings.

[0152] Figure 1A and Figure 1B is a schematic cross-sectional view showing an example of a display device including the organic light-emitting element of the present invention and a transistor connected to the organic light-emitting element.

[0153] Figure 1A An example of a pixel as a component of a display device according to the present embodiment is shown. The pixel includes a sub-pixel 20. The sub-pixels are divided into 20R, 20G, and 20B according to the emitted light. The color of the emitted light can be distinguished by the wavelength of the light emitted from the light-emitting layer, or selective penetration or color conversion of the light emitted from the sub-pixel can be performed by a color filter or the like. Each sub-pixel includes a first electrode 12 as a reflective electrode on an interlayer insulating layer 11, an insulating layer 13 covering the edge of the first electrode 12, an organic compound layer 14 covering the first electrode 12 and the insulating layer 13, a second electrode 15, a protective layer 16, and a color filter 17. The first electrode 12, the organic compound layer 14, and the second electrode 15 constitute an organic light-emitting element 18 of the present embodiment.

[0154] The transistor or the capacitor may be disposed under or inside the interlayer insulating layer 11. The transistor and the first electrode 12 may be electrically connected to each other via a contact hole (not shown).

[0155] The insulating layer 13 is also called a bank or a pixel separation film. The insulating layer 13 covers the end of the first electrode 12 and is arranged to surround the first electrode 12. The portion of the first electrode 12 not provided with the insulating layer 13 is in contact with the organic compound layer 14 and becomes a light-emitting region.

[0156] The second electrode 15 may be a transparent electrode, a reflective electrode or a semi-transparent electrode.

[0157] The protective layer 16 reduces the penetration of moisture into the organic compound layer 14. The protective layer 16 is shown as a single layer, but may be a multilayer. The multilayer may include an inorganic compound layer and an organic compound layer.

[0158] The color filters 17 are divided into 17R, 17G, and 17B according to their colors. The color filters can be formed on a planarization film (not shown). In addition, a resin protective layer (not shown) can be provided on the color filters. The color filters 17 can be formed on the protective layer 16, or can be provided on an opposing substrate such as a glass substrate and then attached.

[0159] Figure 1B The display device includes an organic light-emitting element 36 and a TFT 28, which is an example of a transistor. Specifically, an insulating layer 22 is provided on a substrate 21 such as glass or silicon, and a TFT 28 including a gate electrode 23, a gate insulating film 24, a semiconductor layer 25, a drain electrode 26, and a source electrode 27 is arranged on the insulating layer 22. An insulating film 29 is provided on the TFT 28, and an anode 31 constituting the organic light-emitting element 36 and the source electrode 27 are connected to each other via a contact hole 30 provided in the insulating film 29.

[0160] The system of electrical connection of the electrodes (anode 31 and cathode 33) included in the organic light emitting element 36 and the electrodes (source electrode 27 and drain electrode 26) included in the TFT 28 is not limited to Figure 1B That is, one of the anode 31 and the cathode 33 and one of the source electrode 27 and the drain electrode 26 may be electrically connected to each other. TFT28 refers to a thin film transistor.

[0161] On the cathode 33 , a first protective layer 34 and a second protective layer 35 are provided for reducing degradation of the organic light emitting element.

[0162] In the organic light emitting element 36 according to the present embodiment, the light emission luminance is controlled by the TFT 28 , and an image can be displayed by the light emission luminance of each of the plurality of organic light emitting elements 36 arranged in a plane.

[0163] Figure 1B The display device uses a transistor as a switching element, but another switching element may be used instead.

[0164] exist Figure 1B The transistors used in the display device are not limited to TFTs including an active layer on an insulating surface of a substrate and may be transistors using a single-crystal silicon wafer. The active layer may be non-single-crystal silicon, such as amorphous silicon and microcrystalline silicon, or a non-single-crystal oxide semiconductor, such as indium zinc oxide and indium gallium zinc oxide.

[0165] A transistor formed of low-temperature polysilicon or an active matrix driver formed on a substrate such as a Si substrate can be used. "On a substrate" can also be referred to as "inside a substrate." Whether to set a transistor in the substrate or to use a TFT is selected based on the size of the display portion. For example, when the size of the display portion is about 0.5 inches, it is preferred to set an organic light-emitting element on a Si substrate. Here, formed in a substrate means that a transistor is produced by processing the substrate itself such as a Si substrate. That is, having a transistor in a substrate can also be considered to mean that the substrate and the transistor are formed integrally.

[0166] Figure 2 1 is a schematic diagram illustrating an example of a display device according to the present invention. Display device 1000 includes a touch panel 1003, a display panel 1005, a frame 1006, a circuit substrate 1007, and a battery 1008 between an upper cover 1001 and a lower cover 1009. Touch panel 1003 and display panel 1005 are connected to flexible printed circuits (FPCs) 1002 and 1004, respectively. Circuit substrate 1007 has transistors printed thereon. If the display device is not a display device, battery 1008 does not need to be provided, and even if the device is portable equipment, it can be provided in another location.

[0167] The display device according to the present embodiment may include red, green, and blue color filters. The red, green, and blue color filters may be arranged in a delta arrangement.

[0168] The display device according to this embodiment can be used in the display unit of a portable terminal. In this case, the display device can have both display and operation functions. Examples of portable terminals include portable phones such as smartphones, tablet computers, and head-mounted displays.

[0169] The display device according to this embodiment can be used in the display unit of an imaging device, which includes an optical unit including a plurality of lenses and an imaging element that receives light passing through the optical unit. The imaging device may include a display unit that displays information acquired by the imaging element. The display unit may be a display unit exposed to the outside of the imaging device or a display unit configured in a viewfinder. The imaging device may be a digital still camera or a digital video camera.

[0170] Figure 3A 11 is a schematic diagram illustrating an example of an imaging device according to the present invention. Imaging device 1100 includes a viewfinder 1101, a rear display 1102, an operating unit 1103, and a housing 1104. Viewfinder 1101 may include a display device according to this embodiment. In this case, the display device may display not only the image to be captured but also environmental information and imaging instructions. Environmental information may include the intensity of external light, the direction of external light, the speed of the subject's movement, and the possibility that the subject is obscured by an obstruction.

[0171] Since the optimal timing for capturing images is only short, it is better to display information as quickly as possible. Therefore, it is preferable to use a display device using the organic light-emitting element of the present invention because of its high response speed. Display devices using organic light-emitting elements can be more suited to use than liquid crystal display devices, which require high display speeds.

[0172] The imaging device 1100 includes an optical unit (not shown). The optical unit includes multiple lenses and forms an image in an imaging element housed in a housing 1104. The lenses can adjust the focus by adjusting their relative positions. This operation can also be automated. The imaging device may also be referred to as a photoelectric conversion device. The photoelectric conversion device may employ a method for capturing images, such as detecting differences from previous images or cutting out images from a continuously recorded image, instead of sequentially capturing images.

[0173] Figure 3B 1 is a schematic diagram showing an example of an electronic device according to the present invention. Electronic device 1200 includes a display unit 1201, an operating unit 1202, and a housing 1203. Housing 1203 may include a circuit, a printed circuit board having the circuit, a battery, and a communication unit. Operating unit 1202 may be a button or a touch panel type reaction unit. The operating unit may be a biometric recognition unit that performs fingerprint recognition to unlock a lock. Electronic equipment including a communication unit may also be referred to as communication equipment. The electronic equipment may include a lens and an imaging element to further have a camera function. The image captured by the camera function is displayed on the display unit. Examples of electronic equipment include smartphones and laptop personal computers.

[0174] Figure 4A and Figure 4B is a schematic diagram showing an example of a display device according to the present invention. Figure 4A The display device 1300 includes a frame 1301 and a display portion 1302. The display portion 1302 uses a light-emitting device of an organic light-emitting element according to the present invention. The display device 1300 includes a base 1303 that supports the frame 1301 and the display portion 1302. The base 1303 is not limited to Figure 4A The lower side of the frame 1301 can also serve as a base. The frame 1301 and the display portion 1302 can be curved. The radius of curvature can be greater than 5000 mm and less than 6000 mm.

[0175] Figure 4B is a schematic diagram showing another example of the display device according to the present invention. Figure 4BThe display device 1310 is configured to be bendable and is a so-called foldable display device. The display device 1310 includes a first display portion 1311, a second display portion 1312, a housing 1313, and a folding point 1314. The first display portion 1311 and the second display portion 1312 include a light-emitting device using an organic light-emitting element according to the present invention. The first display portion 1311 and the second display portion 1312 can be a seamless display device. The first display portion 1311 and the second display portion 1312 can be divided at a folding point. The first display portion 1311 and the second display portion 1312 can display images different from each other, or the first and second display portions can display one image.

[0176] Figure 5A 14 is a schematic diagram illustrating an example of a lighting device according to the present invention. Lighting device 1400 includes a housing 1401, a light source 1402, a circuit substrate 1403, an optical filter 1404, and a light diffuser 1405. Light source 1402 includes an organic light-emitting element according to the present invention. Optical filter 1404 can be a filter for enhancing the color rendering properties of the light source. Light diffuser 1405 can effectively diffuse the light from light source 1402, for example, to illuminate the light, thereby delivering the light to a wide area. Optical filter 1404 and light diffuser 1405 can be positioned on the light-emitting side of the illumination light. A cover can be provided on the outermost portion as needed.

[0177] The lighting device is, for example, a device for indoor lighting. The lighting device can be a device that emits white, daylight white, or any other color of light ranging from blue to red. The lighting device may include a light modulation circuit that modulates these colors of light. The lighting device includes the organic light-emitting element of the present invention and a power supply circuit connected thereto. The power supply circuit is a circuit that converts AC voltage into DC voltage. The color temperature of white is 4200K, and the color temperature of daylight white is 5000K. The lighting device may include a color filter.

[0178] The lighting device according to the present invention may include a heat dissipation portion. The heat dissipation portion releases heat in the device to the outside, and examples thereof include metals with high specific heat and liquid silicon.

[0179] Figure 5B 1 is a schematic diagram showing a car as an example of a mobile object according to the present invention. The car includes taillights, which are an example of a lighting device. The car 1500 includes taillights 1501, and the taillights can be in a taillight-on mode when performing a braking operation, etc.

[0180] Taillight 1501 includes an organic light-emitting element according to the present invention. The taillight may include a protective member to protect the organic light-emitting element. The material of the protective member is not limited, as long as it is transparent and has a certain degree of strength. However, the protective member is preferably made of polycarbonate, etc. Polycarbonate may be mixed with a furandicarboxylic acid derivative or an acrylonitrile derivative, etc.

[0181] Automobile 1500 may include a vehicle body 1503 and a window 1502 attached thereto. The window may be a transparent display, rather than a window for viewing the front and rear of the vehicle. The transparent display includes an organic light-emitting element according to the present invention. Components of the organic light-emitting element, such as electrodes, are made of transparent members.

[0182] The mobile object according to the present invention may be a ship, an aircraft, or an unmanned aerial vehicle. The mobile object includes a main body and a lighting device mounted on the main body. The lighting device emits light for indicating the position of the main body. The lighting device includes an organic light-emitting element according to the present invention.

[0183] Will refer to Figure 6A and Figure 6B Application examples of the display devices of each of the above embodiments are described. The display devices can be applied to systems that can be worn as wearable devices, such as smart glasses, head-mounted displays, and smart contact lenses. The imaging and display devices used in such application examples include imaging devices capable of photoelectrically converting visible light and display devices capable of emitting visible light.

[0184] Figure 6A Glasses 1600 (smart glasses) according to one application example are shown. An imaging device 1602, such as a complementary metal oxide semiconductor sensor and a single photon avalanche diode, is provided on the front side of a lens 1601 of the glasses 1600. The display device of each of the above embodiments is provided on the back side of the lens 1601.

[0185] The glasses 1600 further include a controller 1603. The controller 1603 functions as a power source for supplying power to the imaging device 1602 and the display device according to various embodiments. The controller 1603 controls the operation of the imaging device 1602 and the display device. The lens 1601 forms an optical system for focusing light in the imaging device 1602.

[0186] Figure 6B Another embodiment of glasses 1610 (smart glasses) is shown. Glasses 1610 include a controller 1612 and are connected to Figure 6AThe camera device and the display device corresponding to the camera device 1602 are mounted on the controller 1612. In the lens 1611, the camera device in the controller 1612 and the optical system for projecting the light emitted from the display device are formed, and the image is projected to the lens 1611. The controller 1612 functions as a power supply for supplying power to the camera device and the display device, and also controls the operation of the camera device and the display device. The controller may include a line of sight detection unit for detecting the line of sight of the wearer. The line of sight may be detected using infrared light. The infrared light emitting unit emits infrared light to the eyeball of the user who is looking at the displayed image. The camera unit including the light receiving element detects the reflected light of the infrared light emitted from the eyeball to obtain a camera image of the eyeball. In the plan view, the reduction in image quality is reduced by a device for reducing the light from the infrared light emitting unit to the display unit.

[0187] The user's line of sight to the displayed image is detected from a camera image of the eyeball obtained by infrared light photography. Any known method can be used to detect the line of sight using the camera image of the eyeball. As an example, a line of sight detection method based on a Purkinje image by reflecting irradiated light on the cornea can be used. More specifically, a line of sight detection process based on a pupil-corneal reflection method is performed. Based on the image of the pupil included in the camera image of the eyeball and the Purkinje image, a line of sight vector representing the direction (rotation angle) of the eyeball is calculated using the pupil-corneal reflection method, and the user's line of sight is detected.

[0188] The display device according to the present invention includes a camera device, which includes a light receiving element and can control the image displayed on the display device based on the line of sight information of the user from the camera device. Specifically, the display device determines a first viewing area for close viewing by the user and a second viewing area outside the first viewing area based on the line of sight information. The first viewing area and the second viewing area can be determined by a controller of the display device, or can be received as those determined by an external controller. The display area of ​​the display device can be controlled so that the display resolution of the first viewing area is higher than the display resolution of the second viewing area. That is, the resolution of the second viewing area can be lower than the resolution of the first viewing area.

[0189] The display area includes a first display area and a second display area different from the first display area, and a high-priority area is determined from the first display area and the second display area based on the line of sight information. The first viewing area and the second viewing area can be determined by a controller of the display device, or can be received as those determined by an external controller. The resolution of the high-priority area can be controlled to be higher than the resolution of areas outside the high-priority area. In other words, the resolution of relatively low-priority areas can be reduced.

[0190] AI can be used to determine the first viewing area and the high-priority area. The AI ​​can be a model configured to estimate the angle of the line of sight from the eye image and the distance to the target in front of the line of sight, using the image of the eye and the direction the eye actually views in the image as training data. The AI ​​program can be included in the display device, the camera device, or an external device. If the external device includes the AI ​​program, the AI ​​program is transmitted to the display device via communication.

[0191] When the display is controlled based on visual detection, the display device can be applied to smart glasses, which further include a camera for capturing external images. The smart glasses can display the captured external information in real time.

[0192] Figure 7A 17 is a schematic diagram illustrating an example of an image forming apparatus according to one embodiment of the present invention. Image forming apparatus 1700 is an electrophotographic image forming apparatus and includes a photoreceptor 1707, an exposure light source 1708, a charging unit 1710, a developing unit 1711, a transfer device 1712, a conveying roller 1713, and a fixing device 1715. Light 1709 is irradiated from exposure light source 1708 to form an electrostatic latent image on the surface of photoreceptor 1707. Exposure light source 1708 includes an organic light-emitting element according to the present invention. Developing unit 1711 includes a toner, etc. Charging unit 1710 charges photoreceptor 1707. Transfer device 1712 transfers the developed image to recording medium 1714. Conveying roller 1713 conveys recording medium 1714. Recording medium 1714 is, for example, paper. Fixing device 1715 fixes the image formed on recording medium 1714.

[0193] Figure 7B and Figure 7C Each diagram shows an exposure light source 1708 and is a schematic diagram illustrating a configuration in which multiple light-emitting units 1726 are arranged on a long substrate. Arrow 1727 indicates a direction parallel to the axis of the photoreceptor and represents the row direction in which the organic light-emitting elements are arranged. This row direction is the same as the direction of the axis about which the photoreceptor 1707 rotates. This direction may also be referred to as the long axis direction of the photoreceptor 1707. Figure 7B A configuration is shown in which the light emitting portion 1726 is arranged along the long axis direction of the photoreceptor 1707 . Figure 7C Shown with Figure 7B The first and second columns are arranged at different positions in the row direction. In the first column, the plurality of light-emitting sections 1726 are arranged at intervals. The second column includes light-emitting sections 1726 at positions corresponding to the intervals between light-emitting sections 1726 in the first column. In other words, the plurality of light-emitting sections 1726 are also arranged at intervals in the row direction. Figure 7CThe configuration can be rephrased as, for example, a lattice configuration, a houndstooth configuration, or a checkered pattern.

[0194] As described above, by using a device using the organic light emitting element according to the present invention, a display having good image quality and being stable for a long time can be achieved.

[0195] Example

[0196] The present invention will be described by way of examples. However, the present invention is not limited to such examples. The compounds used in the examples are synthesized according to known synthetic methods.

[0197] Table 1 shows the HOMO and LUMO levels of the light-emitting layer materials used in the Examples. The HOMO level is the ionization potential of a 50 nm thick film of each compound produced by vacuum evaporation, measured using a RIKEN KEIKI Co., Ltd. AC-3. The LUMO level is obtained by measuring the absorption spectrum of the film produced as described above and subtracting the light absorption edge, determined as the band gap, from the ionization potential.

[0198] [Table 1]

[0199] Compound HOMO(eV) LUMO(eV) EM1 -6.0 -3.1 EM4 -6.0 -2.9 EM22 -6.1 -3.0 EM23 -6.0 -3.0 B-1 -6.1 -3.3 B-8 -6.1 -3.4 B-20 -6.1 -3.5 B-30 -6.1 -3.5 B-33 -6.1 -3.4 B-52 -6.2 -3.5 G-7 -5.9 -3.5 G-11 -5.9 -3.5 G-14 -5.9 -3.4 G-15 -5.8 -3.4 R-12 -5.6 -3.5 R-18 -5.6 -3.6 R-21 -5.6 -3.6

[0200] (Example 1)

[0201] In this embodiment, an organic light-emitting element of a top emission structure is produced in which an anode, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer and a cathode are sequentially formed on a substrate.

[0202] A Ti film with a thickness of 40 nm was formed on a glass substrate by sputtering and patterned by photolithography to form an anode. The anode was adjusted to have a thickness of 3 mm. 2 The electrode area is then cleaned.

[0203] Subsequently, the electrode-provided substrate produced above was attached to a vacuum evaporation apparatus (manufactured by ULVAC, Inc.) and prepared for evaporation of the evaporation material, and then evacuated to 1.33×10 -4 Pa(1×10 -6 Torr). Subsequently, the interior of the chamber was subjected to UV / ozone cleaning. Then, each layer having the layer composition shown in Table 2 was formed. Subsequently, the substrate was transferred to a glove box, and the glove box was sealed with a glass cover containing a desiccant in a nitrogen atmosphere to obtain an organic light-emitting element.

[0204] [Table 2]

[0205]

[0206] The obtained organic light emitting element was connected to a voltage applying device and its characteristics were evaluated. The current-voltage characteristics were measured with a microammeter 4140B manufactured by Hewlett-Packard, and the chromaticity was evaluated with an "SR-3" manufactured by TOPCON Corporation. The luminous brightness was measured with a BM7 manufactured by TOPCON Corporation. When emitting 2000 cd / m 2 When the luminance of the organic white light emitting element was 1.5 mmol / L, the current efficiency was measured from the current value and the luminance of the luminescent element, and was 4.5 cd / A. Therefore, the obtained organic white light emitting element was good.

[0207] In addition, at 2000cd / m 2 The initial brightness of the CMOS was continuously driven and the brightness degradation rate after 100 hours was measured. The results are shown in Table 3.

[0208] (Examples 2 to 22 and Comparative Examples 1 to 17)

[0209] The organic light-emitting elements were produced and their characteristics were evaluated in the same manner as in Example 1, except that the light-emitting layer of Example 1 was changed to the configuration shown in Tables 3 to 5. The results are shown in Tables 3 to 5.

[0210] The current efficiency was expressed as a ratio to the current efficiency of Example 5 which was set to 1.0, and the durability evaluation was expressed as a ratio to the luminance degradation rate of Example 5 which was set to 1.0.

[0211] In Tables 3 to 5, “ΔHOMO” means the difference in HOMO energy level (HOMOd2-HOMOh1) between the second light-emitting material and the first organic compound in the first light-emitting layer, and “ΔLUMO” means the difference in LUMO energy level (LUMOh2-LUMOd3) between the second organic compound and the third light-emitting material in the second light-emitting layer.

[0212]

[0213]

[0214]

[0215] Examples 1 to 3 and Comparative Examples 2 and 3 show that when the content of the second light-emitting material is less than 2.0 mass%, both current efficiency and durability characteristics improve. This is because the low content of the second light-emitting material improves the hole-trapping properties of the first light-emitting layer, and the electron blocking layer deteriorates due to the proximity of the recombination region to the interface between the first light-emitting layer and the electron blocking layer.

[0216] When the contents of the first light-emitting material and the second light-emitting material are the same as in Comparative Example 1, the balance of red, green, and blue light emissions is greatly disrupted to significantly reduce current efficiency, which is undesirable.

[0217] Examples 4-6 and Comparative Example 4 show that a high content of the third light-emitting material improves current efficiency and durability. This is because a high content of the third light-emitting material improves the electron-trapping properties of the second light-emitting layer and reduces degradation of the electron-blocking layer by keeping the recombination region away from the interface between the first light-emitting layer and the electron-blocking layer.

[0218] As shown in Examples 7 and 8, since current efficiency is reduced by concentration quenching when the content of the first light-emitting material is high, the content is preferably less than 0.3 mass % and more preferably less than 0.2 mass %.

[0219] Examples 9-11 demonstrate that durability improves when the thickness of the first light-emitting layer is greater than that of the second light-emitting layer. This is because the greater thickness of the first light-emitting layer keeps the recombination region away from the interface between the first light-emitting layer and the electron-blocking layer, thus reducing degradation of the electron-blocking layer.

[0220] As shown in Comparative Examples 5-15, if Expression [4] is not satisfied, current efficiency and durability characteristics deteriorate. This is because charges are not confined in the light-emitting layer and the hole-trapping ability of the first light-emitting layer is not sufficiently relaxed to cause recombination at the interface with the electron blocking layer.

[0221] Based on the above findings, the organic light-emitting element of the present invention not only achieves delocalization of charge and recombination zones within the light-emitting layer, but also improves driving durability by keeping the recombination zones slightly away from the interface with the first light-emitting layer having an electron blocking layer. Therefore, by reducing the content of the light-emitting material in the first light-emitting layer to moderate the hole-trapping ability of the first light-emitting layer, and by strengthening the electron-trapping ability of the second light-emitting layer, the recombination zones are retracted from the interface, thereby improving driving durability.

[0222] (Examples 23 to 29 and Comparative Examples 18 to 20)

[0223] Organic light-emitting elements were produced in the same manner as in Examples 2, 22, and 18, except that the adjacent layer was changed to the material shown in Table 6, and the characteristics were evaluated.

[0224]

[0225] In Examples 2 and 23-27, efficiency and durability improved compared to Comparative Example 18, even though the materials of the light-emitting layers were the same. This is because the adjacent layer in Comparative Example 18 was a compound containing heteroatoms and had high chemical reactivity, which easily caused degradation during operation. In contrast, the adjacent layers in Examples 2 and 23-27 were hydrocarbon compounds and had high stability, which suppressed degradation during operation.

[0226] The same effect was observed in Examples 22, 28, 20, and 29 and Comparative Examples 19 and 20, which had different configurations of the light-emitting layers.

[0227] (Examples 30 and 31 and Comparative Examples 21-29)

[0228] An organic light-emitting element was produced in the same manner as in Example 2, except that the materials and concentrations of the light-emitting layer and the adjacent layer were changed to those shown in Table 7, and the characteristics were evaluated.

[0229]

[0230] Example 2 and Comparative Examples 21-23 show examples in which the concentration of the second luminescent material in the first luminescent layer was varied. Reducing the concentration of the second luminescent material to less than 2% improved efficiency and durability. This is because reducing the concentration of the second luminescent material reduces the hole-trapping capacity of the first luminescent layer and shifts the recombination zone toward the second luminescent layer (receding from the electron-blocking layer).

[0231] In Comparative Examples 18 and 24, the adjacent layer was further changed from a stable hydrocarbon compound to a heteroatom-containing compound, and efficiency and durability were deteriorated compared to Example 2 and Comparative Example 23. This is because, as described above, the adjacent layer is a heteroatom-containing compound and is easily deteriorated.

[0232] The third light emitting material was changed in Example 30 and Comparative Examples 25 to 27. Even if the molecular structure of the third light emitting material was greatly changed, the same effect was obtained due to the concentration of the second light emitting material and the adjacent layer composed of hydrocarbon.

[0233] The relationship between the concentrations of the third luminescent material and the first luminescent material was varied in Example 31 and Comparative Examples 28 and 29. Regardless of the concentrations of these luminescent materials, the same effects were achieved due to the concentration of the second luminescent material and the adjacent layer composed of hydrocarbon.

[0234] The present invention is not limited to the above embodiments, and various changes and modifications can be made without departing from the spirit and scope of the present invention. Therefore, in order to disclose the scope of the present invention, the following claims are attached.

[0235] This application claims the benefit of Japanese Patent Application No. 2023-015298, filed February 3, 2023, and Japanese Patent Application No. 2023-139102, filed August 29, 2023, which are hereby incorporated by reference herein in their entirety.

[0236] Description of Reference Numerals

[0237] 12 first electrode

[0238] 15 second electrode

[0239] 18, 36 organic light-emitting elements

[0240] 1000, 1300, 1310 display devices

[0241] 1100 camera equipment

[0242] 1104, 1203, 1313 housings

[0243] 1200 electronic equipment

[0244] 1201, 1302, 1311, 1312 display units

[0245] 1402 Light Source

[0246] 1404 Optical Filter

[0247] 1405 Light Diffuser

Claims

1. An organic light-emitting element comprising, in order, a first electrode, a first light-emitting layer, a second light-emitting layer, and a second electrode, wherein the first light-emitting layer comprises a first organic compound, a first light-emitting material, and a second light-emitting material, and the second light-emitting layer comprises a second organic compound and a third light-emitting material, and satisfies the following formulas [1] to [4]: [1](HOMOd2-HOMOh1)<(LUMOh2-LUMOd3); [2] The content of the first luminescent material is less than the content of the second luminescent material; [3] the content of the first luminescent material is less than the content of the third luminescent material; and [4] The content of the second luminescent material is less than 2.0% by mass, HOMOh1: HOMO energy level of the first organic compound; HOMOd2: HOMO energy level of the second luminescent material; LUMOh2: LUMO energy level of the second organic compound; and LUMOd3: LUMO energy level of the third luminescent material. 2 . The organic light-emitting element according to claim 1 , comprising an adjacent layer on the second electrode side of the second light-emitting layer, wherein the adjacent layer is made of an organic compound composed of hydrocarbon.

3. An organic light-emitting element comprising, in order, a first electrode, a first light-emitting layer, a second light-emitting layer, an adjacent layer, and a second electrode, wherein the first light-emitting layer comprises a first organic compound, a first light-emitting material, and a second light-emitting material, the second light-emitting layer comprises a second organic compound and a third light-emitting material, the adjacent layer is made of an organic compound composed of a hydrocarbon, and satisfies the following formula [4]: [4] The content of the second luminescent material is less than 2.0% by mass. 4 . The organic light-emitting element according to claim 2 , wherein the organic compound composed of hydrocarbons includes a condensed polycyclic aromatic ring having four or more rings.

5. The organic light emitting element according to claim 2 or 3, wherein the organic compound composed of hydrocarbons consists only of sp 2 Carbon composition. 6 . The organic light-emitting element according to claim 1 , comprising a layer including an arylamine derivative on the first electrode side of the first light-emitting layer. 7 . The organic light-emitting element according to claim 1 , wherein the content of the third light-emitting material is 1.0 mass % or more. 8 . The organic light-emitting element according to claim 1 , wherein the content of the first light-emitting material is less than 0.3% by mass. 9 . The organic light-emitting element according to claim 1 , wherein the thickness of the first light-emitting layer is greater than the thickness of the second light-emitting layer. 10 . The organic light-emitting element according to claim 1 , wherein the first organic compound and the second organic compound are the same compound. 11 . The organic light-emitting element according to claim 1 , wherein the first light-emitting material, the second light-emitting material, and the third light-emitting material each contain a fluoranthene skeleton. 12 . The organic light-emitting element according to claim 1 , wherein the first organic compound and the second organic compound each contain a pyrene skeleton. 13 . The organic light-emitting element according to claim 1 , wherein the compounds constituting the first light-emitting layer and the second light-emitting layer are both hydrocarbons.

14. The organic light-emitting element according to claim 1 or 3, wherein in the first organic compound and the second organic compound, the freely rotatable single bonds are both carbon-carbon bonds, and at least one carbon in the carbon-carbon bond is sp 2 carbon. 15 . A display device comprising a plurality of pixels, wherein at least one of the pixels comprises the organic light emitting element according to claim 1 and a transistor connected to the organic light emitting element.

16. A photoelectric conversion device comprising: An optical section including a plurality of lenses, an imaging element for receiving light passing through the optical section, and a display section for displaying an image captured by the imaging element, wherein the display section includes the organic light emitting element according to any one of claims 1 to 14.

17. An electronic device comprising: A display unit comprising the organic light emitting element according to any one of claims 1 to 14, a housing in which the display unit is provided, and a communication unit provided in the housing and communicating with the outside.

18. A lighting device comprising: A light source comprising the organic light emitting element according to any one of claims 1 to 14, and a light diffusion portion or an optical filter that transmits light emitted from the light source.

19. A mobile object comprising: A lighting device comprising the organic light-emitting element according to any one of claims 1 to 14 and a body provided with the lighting device. 20 . An image forming apparatus comprising a photoreceptor and an exposure light source for exposing the photoreceptor to light, wherein the exposure light source comprises the organic light emitting element according to claim 1 .

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