Organic light-emitting element, display device having the same, imaging device, lighting device, and mobile object

Abstract

To provide an organic light-emitting device having a reduced drive voltage by forming both a first electron transport layer and a second electron transport layer as a mixed layer having a plurality of materials.SOLUTION: An organic light-emitting device has an anode, a light-emitting layer, a first electron transport layer, a second electron transport layer, and a cathode in this order. The second electron transport layer has a first material and a second material different from the first material. The first electron transport layer has a third material and a fourth material different from the third material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an organic light-emitting element, and a display device, an imaging device, a lighting device, and a mobile object having the same. [Background technology]

[0002] An organic light-emitting element is an element having a first electrode, a second electrode, and a light-emitting layer between them. Carriers are injected from these electrodes to generate excitons in the light-emitting layer, and the energy generated when the excitons return to their ground state is used to emit light. In recent years, research and development has been progressing on display devices using organic light-emitting elements, as well as electronic devices and lighting devices that incorporate such devices. In order to improve the performance of these devices, research and development is being actively conducted to lower the operating voltage and extend the lifetime of organic light-emitting elements.

[0003] Patent Document 1 describes an OLED device having a light-emitting layer, a hole-blocking layer, and an electron-transporting layer, and describes that the electron-transporting layer is a mixed layer of multiple compounds in order to reduce the driving voltage while maintaining the purity of the color. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2009-503849 Summary of the Invention [Problem to be solved by the invention]

[0005] The OLED device in Patent Document 1 describes that the electron transport layer is formed as a mixed layer of multiple compounds, but the hole blocking layer disposed between the light-emitting layer and the cathode is composed of a single compound, so there is room for improvement in reducing the driving voltage.

[0006] The present invention has been made in view of the above problems, and an object of the present invention is to provide an organic light-emitting device with a reduced driving voltage. [Means for solving the problem]

[0007] One embodiment of the present invention is an organic light-emitting device having an anode, a light-emitting layer, a first electron transport layer, a second electron transport layer, and a cathode in this order, wherein the second electron transport layer has a first material and a second material different from the first material, and the first electron transport layer has a third material and a fourth material different from the third material. The light-emitting layer includes a fifth material, and the first material to the fifth material satisfy the following relationship: The present invention provides an organic light-emitting device characterized by the above-mentioned. |HOMO(first ingredient)|>|HOMO(second ingredient)|>|HOMO(fourth ingredient)| |HOMO(first ingredient)|>|HOMO(third ingredient)|>|HOMO(fourth ingredient)| |HOMO(Second ingredient)|>|HOMO(Fifth ingredient)| Here, |HOMO(first material)|, |HOMO(second material)|, |HOMO(third material)|, |HOMO(fourth material)|, and |HOMO(fifth material)| represent the absolute value of the HOMO energy of the first material, the absolute value of the HOMO energy of the second material, the absolute value of the HOMO energy of the third material, the absolute value of the HOMO energy of the fourth material, and the absolute value of the HOMO energy of the fifth material, respectively. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an organic light-emitting device with a reduced driving voltage. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view schematically illustrating an example of an embodiment of an organic light-emitting element according to one embodiment of the present invention. [Figure 2] 1 is an energy diagram schematically showing the energy levels around a light-emitting layer that constitutes an organic light-emitting element according to one embodiment of the present invention. [Figure 3] 1 is a schematic cross-sectional view of an example of a display device using an organic light-emitting element according to one embodiment of the present invention. [Figure 4] 1 is a schematic diagram illustrating an example of a display device according to an embodiment of the present invention. [Figure 5] 1A is a schematic diagram illustrating an example of an imaging device according to an embodiment of the present invention, and FIG. 1B is a schematic diagram illustrating an example of an electronic device according to an embodiment of the present invention. [Figure 6] 1A is a schematic diagram illustrating an example of a display device according to an embodiment of the present invention, and FIG. 1B is a schematic diagram illustrating an example of a foldable display device. [Figure 7]1A is a schematic diagram showing an example of an illumination device according to an embodiment of the present invention, and FIG. 1B is a schematic diagram showing an example of an automobile having a vehicle lamp according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] One embodiment of the present invention is an organic light-emitting device having an anode, an emitting layer, a first electron transport layer, a second electron transport layer, and a cathode, in this order, wherein the second electron transport layer has a first material and a second material different from the first material, and the first electron transport layer has a third material and a fourth material different from the third material.

[0011] When both the first electron transport layer and the second electron transport layer are mixed layers containing a plurality of materials, the driving voltage of the organic light emitting device can be reduced.

[0012] When the light-emitting layer and the first electron transport layer are provided in contact with each other, and the first electron transport layer and the second electron transport layer are provided in contact with each other, and the light-emitting layer contains a fifth material, it is preferable that the fifth material and the fourth material are the same compound, and the second material and the third material are the same compound, because adjacent organic compound layers have a common material, thereby reducing the energy barrier between the layers and contributing to a reduction in driving voltage.

[0013] The light-emitting layer may include a fifth material and a sixth material. When the weight of the light-emitting layer is 100 wt %, the fifth material may be a compound having a larger weight ratio in the light-emitting layer than the sixth material. The sixth material may be a light-emitting material. The light-emitting material will be described later.

[0014] An embodiment of the present invention will now be described in more detail with reference to Fig. 1. Fig. 1 is a schematic cross-sectional view showing an embodiment of the present invention.

[0015] The organic light-emitting device shown in FIG. 1 has an anode 2, a hole transport layer 3, an electron blocking layer 4, an emitting layer 5, a first electron transport layer 6, a second electron transport layer 7, an electron injection layer 8, and a cathode 9 stacked in this order on an insulating layer 1. The emitting layer 5, the first electron transport layer 6, and the second electron transport layer 7 are stacked adjacent to each other. The emitting layer 5 may be formed from multiple layers, and other functional layers may be provided between the multiple emitting layers. While FIG. 1 shows a typical configuration, a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, etc. may be further added as necessary, or the configuration may not include the above organic compound layers.

[0016] FIG. 2 is an example of an energy diagram showing a schematic representation of the energy levels of the electron blocking layer, the light-emitting layer, the first electron transport layer, and the second electron transport layer that constitute an organic light-emitting element according to one embodiment of the present invention.

[0017] The HOMO energy and LUMO energy are based on the vacuum level, and for normal molecules, they take negative values. In this specification, when describing the HOMO energy and LUMO energy, absolute values are used. In other words, they are described using positive values. The HOMO is the highest occupied molecular orbital, and the LUMO is the lowest unoccupied molecular orbital.

[0018] In this embodiment, the first material is electron transport material B, the second material is electron transport material A, the third material is electron transport material A, the fourth material is host material A, the fifth material is host material A, and the sixth material is emitting dopant A.

[0019] In the organic light-emitting device according to this embodiment, both the first electron transport layer and the second electron transport layer are mixed layers containing a plurality of materials, and therefore the driving voltage can be reduced. Furthermore, by having the following configuration, the effect of reducing the driving voltage can be further enhanced.

[0020] (1) The light-emitting layer, the first electron transport layer, and the second electron transport layer have a common material among adjacent layers. 2, in this embodiment, the second electron transport layer contains electron transport material A and electron transport material B, and the first electron transport layer contains electron transport material A and host material A, thereby reducing the energy barrier when electrons are injected from the cathode side to the light-emitting layer. It is believed that mixing the materials causes an interaction between the materials, resulting in an energy level intermediate between the energy levels of these material species, thereby lowering the injection barrier.

[0021] In this embodiment, both the first electron transport layer and the second electron transport layer are mixed layers containing multiple materials. If there are two electron transport layers and only one mixed layer, the injection barrier is not sufficiently reduced, resulting in a high driving voltage. In contrast, by having two electron transport layers and both being mixed layers, the injection barrier can be significantly reduced.

[0022] Furthermore, when the mixed layer is a single layer and the host material is contained in the mixed layer, holes are injected from the light-emitting layer into the mixed layer, and then into the electron injection layer and even the cathode, which significantly reduces the luminous efficiency.

[0023] Furthermore, in addition to the configuration (1), it is preferable that the element configuration satisfies the following conditions. (2) Electron transport material A and host material A are composed of compounds consisting only of hydrocarbons. (3) Electron transport material B is composed of a compound containing nitrogen-containing aromatic compounds. (4) The following relationship is satisfied: Absolute value of HOMO: (Electron transport material A) < (Electron transport material B) (5) The following relationship is satisfied: Absolute value of HOMO: (Host material A) < (Electron transport material A)

[0024] These configurations will be described below. (2) Electron transport material A and host material A are composed of materials consisting only of hydrocarbons. In this embodiment, the compounds used as the electron transport material A and the host material A are not particularly limited, but compounds that do not have bonds with low bond stability in their molecular structure are preferred. Furthermore, structures that do not contain nitrogen-containing aromatic compounds in their molecules are preferred. In other words, the electron transport material A and the host material A are preferably compounds consisting only of hydrocarbons.

[0025] When a compound having a bond with low bond stability in its molecular structure, i.e., an unstable bond with low bond energy such as an amino group, is contained as a host in the light-emitting layer constituting an organic light-emitting device, the compound is likely to undergo degradation during operation of the device, which is why the durability life of the organic light-emitting device is likely to be shortened.

[0026] Taking the compounds A-1, A-2, and B-1 shown below as examples, the bonds with low bond stability are the bond connecting the carbazole ring and the phenylene group and the bond connecting the amino group and the phenyl group (nitrogen-carbon bond). Bonds connecting carbon to carbon, such as compound B-1, have higher bond stability. The calculation method used was b3-lyp / def2-SV(P).

[0027] [ka]

[0028] It is a free-standing design and is available in Gaussian09(Gaussian09,RevisionC.01,MJFrisch,GWTrucks,HBSchlegel,GEScuseria, MARobb, JRCheeseman, G. Scalmani, V. Barone, B. Mennucci, G. Petersson, H. Nakatsuji, M. Caricato, X. Li, HPHratch ian, AFIzmaylov, J. Bloino, G. Zheng, JLSonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, [ PMC free article ] [ PubMed ] Nakajima T., Honda Y., Kitao O., Nakai H., Vreven T., Montgomery J. Montgomery, Jr., Peralta J. Ogliaro, Bearpark M., JJHeyd ,E.Brothers,KNKudin,VNStaroverov,T.Keith,R.Kobayashi,J.Normand,K.Raghavachari,A.Rendell,JCBurant,S SIyengar, J. Thomas, M. Cossi, N. Rega, JMMillam, M. Klene, JEKnox, JBCross, V. Bakken, C. Adamo, J. Jaramillo, R. Go mperts,REStratmann,O.Yazyev,AJAustin,R.Cammi,C.Pomelli,JWOchterski,RLMartin,K.Morokuma,VGZakrzewsk i,GAVoth,P.Salvador,JJDannenberg,S.Dapprich,ADDaniels,O.Farkas,JBForesman,JVOrtiz,JCioslowski,and DJFox,Gaussian,Inc.,Wallingford CT,2010.)

[0029] Compounds containing nitrogen-containing aromatic groups in the molecule, such as the exemplified compounds A-1 and A-2, lack stability against oxidation and are therefore preferably not injectable with holes. On the other hand, the light-emitting layer and the first electron-transporting layer according to this embodiment are organic compound layers into which holes are easily injected. Therefore, the host material for the light-emitting layer and the first electron-transporting layer preferably have a structure that does not contain nitrogen-containing aromatic groups, i.e., are hydrocarbon compounds.

[0030] In view of the above, the first material and the second material of the organic light-emitting device according to one embodiment of the present invention are preferably composed of compounds consisting of only hydrocarbons. In other words, the compound shared by the host material of the light-emitting layer and the first electron-transporting layer, and the compound shared by the first electron-transporting layer and the second electron-transporting layer are preferably compounds consisting of only hydrocarbons.

[0031] More specifically, the compound consisting only of hydrocarbons may have an aryl group. The aryl group may have an alkyl group having 1 to 12 carbon atoms as a substituent. The aryl group is preferably selected from benzene, naphthalene, fluorene, benzofluorene, phenanthrene, chrysene, triphenylene, pyrene, fluoranthene, and benzofluoranthene. In other words, a molecular structure composed of aromatic hydrocarbons with up to two rings linearly fused to benzene rings is preferred. This is because it is more stable than compounds containing three or more rings linearly fused to benzene rings, such as anthracene and tetracene.

[0032] Specific examples of the alkyl group having 1 to 12 carbon atoms that the aryl group may have include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neo-pentyl group, a tert-pentyl group, a hexyl group, a heptyl group, and an octyl group.

[0033] (3) Electron transport material B is composed of a heterocyclic compound Since the electron transport material B is contained in the layer that injects electrons from the cathode, a material that easily injects electrons is preferred. Furthermore, the electron transport material B is preferably a material that interacts with an alkali metal compound used in the electron injection layer, such as aluminum lithium or lithium fluoride, to promote electron injection. Therefore, heterocyclic compounds, particularly heterocyclic compounds having a nitrogen atom as a heteroatom, are preferred. The interaction between the nitrogen atom of the heterocyclic compound and the alkali metal can promote electron injection, thereby reducing the driving voltage.

[0034] (4) The following relationship is satisfied: Absolute value of HOMO: (Electron transport material A) < (Electron transport material B) This indicates that the absolute value of the HOMO of electron transport material A is larger than that of electron transport material B. By satisfying this relationship, two electron transport layers are arranged in order of increasing absolute value of the HOMO from the light-emitting layer side. These electron transport layers also function as hole-blocking layers, thereby reducing the flow of holes from the light-emitting layer to the cathode side. More specifically, electron transport material B reduces the flow of holes from the first electron transport layer to the second electron transport layer. This effect reduces hole leakage from the light-emitting layer and improves luminous efficiency. This has the effect of extending the life of the device by reducing the deterioration of the electron transport layer caused by holes leaking into the electron transport layer.

[0035] In particular, when the electron transport layer B is made of a nitrogen-containing aromatic compound, it is prone to deterioration due to hole injection, and therefore it is preferable that the electron transport layer A blocks holes.

[0036] (5) The following relationship is satisfied: Absolute value of HOMO: (Host material A) < (Electron transport material A) By satisfying this relationship, the electron transport material A reduces the flow of holes from the light-emitting layer to the first electron transport layer and reduces the flow of holes from the light-emitting layer to the cathode side.

[0037] This effect reduces hole leakage from the light-emitting layer, improving luminous efficiency, and extends the life of the device by reducing deterioration of the electron transport layer caused by holes leaking into the electron transport layer.

[0038] Specific examples of electron transport materials used in the present invention are shown below. The electron transport material can be arbitrarily selected from those capable of transporting electrons injected from the cathode to the light-emitting layer, and is selected in consideration of the balance with the hole mobility of the hole transport material. Materials having electron transport properties include oxadiazole derivatives, oxazole derivatives, pyrazine derivatives, triazole derivatives, triazine derivatives, quinoline derivatives, quinoxaline derivatives, phenanthroline derivatives, organoaluminum complexes, and fused ring compounds (e.g., fluorene derivatives, naphthalene derivatives, chrysene derivatives, anthracene derivatives, etc.).

[0039] Specific examples of compounds that can be used as electron transporting materials are shown below, but the present invention is not limited to these.

[0040] [ka]

[0041] Among the electron transport materials exemplified above, ET11 to ET22 composed solely of hydrocarbons are preferred as electron transport material A from the viewpoint of the aforementioned bond stability. By using these electron transport materials, an organic light-emitting device with excellent durability can be obtained. As electron transport material B, ET1 to ET10, ET23, and ET24 containing a nitrogen-containing aromatic ring are preferred from the viewpoint of the aforementioned electron injection property.

[0042] Specific examples of hole transport materials used in an organic light-emitting device according to one embodiment of the present invention are shown below. As the hole injection and transport material, a material that can easily inject holes from the anode and a material with high hole mobility so that the injected holes can be transported to the light-emitting layer are preferred. Examples of low-molecular-weight and high-molecular-weight materials that have hole injection and transport properties include triarylamine derivatives, arylcarbazole derivatives, phenylenediamine derivatives, stilbene derivatives, phthalocyanine derivatives, porphyrin derivatives, poly(vinylcarbazole), poly(thiophene), and other conductive polymers. Furthermore, the above-mentioned hole injection and transport materials are also suitable for use in electron blocking layers.

[0043] Specific examples of compounds that can be used as hole injection and transport materials are shown below, but the present invention is not limited to these.

[0044] [ka]

[0045] Specific examples of the light-emitting material used in the organic light-emitting device according to one embodiment of the present invention are shown below. Examples of light-emitting materials mainly involved in the light-emitting function include condensed polycyclic compounds (e.g., fluorene derivatives, naphthalene derivatives, pyrene derivatives, perylene derivatives, tetracene derivatives, anthracene derivatives, rubrene, etc.), quinacridone derivatives, coumarin derivatives, stilbene derivatives, organoaluminum complexes such as tris(8-quinolinolato)aluminum, iridium complexes, platinum complexes, rhenium complexes, copper complexes, europium complexes, ruthenium complexes, and polymer derivatives such as poly(phenylenevinylene) derivatives, poly(fluorene) derivatives, and poly(phenylene) derivatives.

[0046] The light-emitting layer host or light-emitting assist material contained in the light-emitting layer can be a condensed polycyclic compound. More specifically, the compound has an aryl group such as benzene, naphthalene, fluorene, benzofluorene, phenanthrene, chrysene, triphenylene, pyrene, fluoranthene, or benzofluoranthene. These aryl groups may have an alkyl group as a substituent. Specifically, the alkyl group may be an alkyl group having 1 to 12 carbon atoms. In addition to the above-mentioned compounds, examples of the compound include carbazole derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, organoaluminum complexes such as tris(8-quinolinolato)aluminum, and organoberyllium complexes.

[0047] Specific examples of the host material for the light-emitting layer used in the organic light-emitting device according to one embodiment of the present invention are shown below. However, these compounds are merely specific examples, and the present invention is not limited to these.

[0048] [ka]

[0049] Among the exemplified hosts, EMH1 to EMH27 composed only of hydrocarbons are preferred from the viewpoint of the bond stability described above, and EMH1 to EMH21 excluding acene structures such as anthracene and tetracene are more preferred, because the use of these hosts enables the production of organic light-emitting devices with excellent durability.

[0050] Examples of the blue dopant used in the organic light-emitting device according to one embodiment of the present invention include the following, however, the present invention is not limited thereto.

[0051] [ka]

[0052] Among the blue dopants listed above, compounds that do not have a substituted amino group with weak binding energy are particularly preferred. The doping concentration of the blue dopant is preferably 0.1 to 10.0% by weight, more preferably 0.3 to 5.0% by weight.

[0053] The green dopant used in the organic light-emitting device according to one embodiment of the present invention may be, for example, the following: However, the present invention is not limited thereto.

[0054] [ka]

[0055] Among the green dopants listed above, compounds that do not have a substituted amino group with weak binding energy are particularly preferred. The doping concentration of the green dopant is preferably 0.1 to 10.0% by weight, more preferably 0.1 to 5.0% by weight.

[0056] The red dopant used in the organic light-emitting device according to one embodiment of the present invention may be, for example, the following: However, the present invention is not limited thereto.

[0057] [ka]

[0058] Among the red dopants listed above, compounds that do not have substituted amino groups with weak binding energy are particularly preferred. Compounds consisting of hydrocarbons alone are even more preferred. The doping concentration of the red dopant is preferably 0.1 to 5.0% by weight, more preferably 0.1 to 0.5% by weight.

[0059] (Regarding the organic light-emitting element according to this embodiment) The organic light-emitting element according to this embodiment is an organic electroluminescent element having a pair of electrodes and an organic compound layer disposed between the pair of electrodes. The organic compound layer has a light-emitting layer.

[0060] The organic light-emitting element according to this embodiment may have a hole injection layer, a hole transport layer, an electron blocking layer, a hole blocking layer, an electron transport layer, an electron injection layer, an intermediate layer, a charge generation layer, a charge separation layer, and the like in addition to the light-emitting layer.

[0061] The organic light-emitting element may have the following configuration, for example. Anode / Hole transport layer / First light-emitting layer / First electron transport layer / Second electron transport layer / Electron injection layer / CathodeAnode / Hole injection layer / Hole transport layer / First light-emitting layer / First electron transport layer / Second electron transport layer / Electron injection layer / Cathode Anode / hole injection layer / hole transport layer / first light-emitting layer / hole blocking layer / first electron transport layer / second electron transport layer / electron injection layer / cathode Anode / hole injection layer / hole transport layer / first emitting layer / second emitting layer / hole blocking layer / first electron transport layer / second electron transport layer / electron injection layer / cathode Anode / hole injection layer / hole transport layer / first emitting layer / intermediate layer / second emitting layer / hole blocking layer / first electron transport layer / second electron transport layer / electron injection layer / cathode Anode / hole injection layer / hole transport layer / first emitting layer / second emitting layer / third emitting layer / hole blocking layer / first electron transport layer / second electron transport layer / electron injection layer / cathode

[0062] However, these device configuration examples are merely very basic device configurations, and the configuration of the organic light-emitting device according to one embodiment of the present invention is not limited to these.

[0063] Furthermore, various layer configurations can be adopted, such as providing an insulating layer at the interface between the electrode and the organic compound layer, or providing an adhesive layer or an interference layer.

[0064] The device may further include a charge injection layer having a fifth material between the first electrode and the first charge transport layer. The absolute value of the LUMO of the fifth material is preferably equal to or greater than the absolute value of the HOMO of the first material or the absolute value of the HOMO of the second material. This configuration allows for hole injection.

[0065] The organic light-emitting element according to this embodiment may be of a so-called bottom emission type in which light is extracted from the electrode on the substrate side, or of a so-called top emission type in which light is extracted from the side opposite the substrate, or may be used in a double-sided emission configuration.

[0066] In the present invention, the light-emitting layer refers to a layer having a light-emitting function among organic compound layers provided between electrodes. The light-emitting layer may contain a host material, a dopant material, and an assist material. These materials may be referred to as a first material, a second material, and a third material, respectively.

[0067] The host material contained in the light-emitting layer may be the material that has the largest weight ratio among the materials contained in each light-emitting layer. The host material can also be said to be the material that forms the matrix of the light-emitting layer. More specifically, the host material may be a material that has a weight ratio of 50% or more of the materials contained in the light-emitting layer.

[0068] The dopant material contained in the light-emitting layer may be a material that is contained in the light-emitting layer in a weight ratio smaller than that of the host material. More specifically, the dopant is a light-emitting material (light-emitting dopant material) that is responsible for the main emission of light, and may be responsible for emission occupying 50% or more of the emission spectrum of the organic light-emitting device. Furthermore, the dopant material may be a material that is contained in the light-emitting layer in a weight ratio of less than 50% by weight. The dopant material is also called a guest material.

[0069] Here, the dopant material is a compound that is responsible for the main emission in the light-emitting layer. In other words, the light-emitting dopant is responsible for the emission that occupies 50% or more of the emission spectrum of the organic light-emitting device.

[0070] The concentration of the dopant material is 0.01% by weight or more and less than 50% by weight, and preferably 0.1% by weight or more and 10% by weight or less, when the total amount of the compounds constituting the light-emitting layer is taken as 100% by weight. More preferably, the concentration of the dopant material is 0.1% by weight or more and 10% by weight or less to suppress concentration quenching. The dopant material may be uniformly contained throughout the layer made of the host material, or may be contained with a concentration gradient, or may be contained partially in a specific region to provide a region of the host material layer that does not contain the dopant material.

[0071] Furthermore, the organic light-emitting element according to this embodiment may have a plurality of light-emitting layers, at least one of which emits light of a wavelength different from that of the other light-emitting layers, and may be an organic light-emitting element that emits white light by mixing the light of these light-emitting layers.

[0072] In one embodiment of the present invention, the organic light emitting device may have two or more light emitting layers, and each light emitting layer may contain light emitting materials having two or more emission colors.

[0073] The second light-emitting layer may be in contact with the first or second light-emitting layer, or another compound layer may be present between the light-emitting layers. The other compound layer may be a charge-generating layer or the like.

[0074] [Configuration of organic light-emitting element] The organic light-emitting element is provided by forming an anode, an organic compound layer, and a cathode on a substrate. A protective layer, a color filter, etc. may be provided on the cathode. When a color filter is provided, a planarizing layer may be provided between the protective layer and the color filter. The planarizing layer may be made of acrylic resin or the like.

[0075] [substrate] Examples of the substrate include quartz, glass, silicon wafer, resin, and metal. Furthermore, the substrate may be provided with switching elements such as transistors and wiring, and an insulating layer thereon. The insulating layer may be made of any material, as long as it can form contact holes to ensure electrical continuity between the anode 2 and the wiring and can ensure insulation from unconnected wiring. For example, resins such as polyimide, silicon oxide, silicon nitride, etc. can be used.

[0076] [electrode] The electrodes may be a pair of electrodes, a first electrode and a second electrode. The pair of electrodes may be an anode and a cathode. When an electric field is applied in the direction in which the organic light-emitting element emits light, the electrode with a higher potential is the anode, and the other is the cathode. It can also be said that the electrode that supplies holes to the light-emitting layer is the anode, and the electrode that supplies electrons is the cathode.

[0077] One of the pair of electrodes may be a reflective electrode that reflects light, and the other may be a transmissive electrode that transmits light. When a reflective electrode and a transmissive electrode are used in combination in this manner, an optical resonator structure may be formed by adjusting the thickness of the organic compound layer disposed between the pair of electrodes. Alternatively, both of the pair of electrodes may be transmissive electrodes.

[0078] The anode material should have as high a work function as possible. Examples include simple metals such as gold, platinum, silver, copper, nickel, palladium, cobalt, selenium, vanadium, and tungsten, mixtures containing these metals, alloys of these metals, and metal oxides such as tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and zinc indium oxide. Conductive polymers such as polyaniline, polypyrrole, and polythiophene can also be used.

[0079] These electrode materials may be used alone or in combination of two or more. The anode may be composed of one layer or multiple layers.

[0080] When used as a reflective electrode, for example, chromium, aluminum, silver, titanium, tungsten, molybdenum, or alloys or laminates thereof can be used. When used as a transparent electrode, transparent conductive oxide layers such as indium tin oxide (ITO) and indium zinc oxide can be used, but are not limited to these. Photolithography techniques can be used to form the electrodes.

[0081] On the other hand, materials with a low work function are preferred for the cathode. Examples include alkali metals such as lithium, alkaline earth metals such as calcium, and metals such as aluminum, titanium, manganese, silver, lead, and chromium, as well as mixtures containing these metals. Alternatively, alloys combining these metals can be used. For example, magnesium-silver, aluminum-lithium, aluminum-magnesium, silver-copper, and zinc-silver can be used. Metal oxides such as indium tin oxide (ITO) can also be used. These electrode materials can be used alone or in combination. The cathode can have either a single-layer or multi-layer structure. Among these, silver is preferred, and a silver alloy is even more preferred to suppress silver aggregation. The alloy ratio is not critical as long as silver aggregation can be suppressed. For example, a 1:1 ratio is acceptable.

[0082] The cathode may be a top-emission element using an oxide conductive layer such as ITO, or a bottom-emission element using a reflective electrode such as aluminum (Al), and is not particularly limited. The method for forming the cathode is not particularly limited, but DC and AC sputtering methods are more preferred because they provide good film coverage and make it easier to reduce resistance.

[0083] [Protective layer] A protective layer may be provided on the cathode. For example, by adhering glass with a moisture absorbent on the cathode, it is possible to prevent water and other substances from penetrating the organic compound layer, thereby preventing display defects. In another embodiment, a passivation film such as silicon nitride may be provided on the cathode to prevent water and other substances from penetrating the organic EL layer. For example, after forming the cathode 7, the device may be transported to another chamber without breaking the vacuum, and a silicon nitride film with a thickness of 2 μm may be formed by CVD to serve as a protective layer. A protective layer may also be provided using atomic layer deposition (ALD) after the CVD film formation.

[0084] [Color Filter] A color filter may be provided on the protective layer. For example, a color filter taking into consideration the size of the organic light-emitting element may be provided on a separate substrate and then bonded to the substrate on which the organic light-emitting element is provided, or a color filter may be patterned on the protective layer described above using photolithography technology. The color filter may be made of a polymer.

[0085] [Planarization layer] A planarizing layer may be provided between the color filter and the protective layer. The planarizing layer may be made of an organic compound, and may be either a low molecular weight or a high molecular weight, but is preferably a high molecular weight.

[0086] The planarizing layer may be provided above or below the color filter, and may be made of the same or different materials, such as polyvinyl carbazole resin, polycarbonate resin, polyester resin, ABS resin, acrylic resin, polyimide resin, phenol resin, epoxy resin, silicone resin, and urea resin.

[0087] [Counter substrate] A counter substrate may be provided on the planarization layer. The counter substrate is called a counter substrate because it is provided at a position corresponding to the aforementioned substrate. The counter substrate may be made of the same material as the aforementioned substrate.

[0088] [Organic layer] The organic compound layers (hole injection layer, hole transport layer, electron blocking layer, light emitting layer, hole blocking layer, electron transport layer, electron injection layer, etc.) constituting the organic light emitting device according to one embodiment of the present invention are formed by the method shown below.

[0089] The organic compound layer constituting the organic light-emitting device according to one embodiment of the present invention can be formed by dry processes such as vacuum deposition, ionization deposition, sputtering, plasma, etc. Alternatively to the dry process, a wet process can be used in which the compound is dissolved in an appropriate solvent and a layer is formed by a known coating method (for example, spin coating, dipping, casting, LB method, inkjet method, etc.).

[0090] Here, when a layer is formed by a vacuum deposition method or a solution coating method, crystallization is unlikely to occur and the layer has excellent stability over time. When a film is formed by a coating method, the film can be formed by combining with an appropriate binder resin.

[0091] Examples of the binder resin include, but are not limited to, polyvinylcarbazole resin, polycarbonate resin, polyester resin, ABS resin, acrylic resin, polyimide resin, phenol resin, epoxy resin, silicone resin, and urea resin.

[0092] These binder resins may be used singly or in combination as homopolymers or copolymers, and may further contain known additives such as plasticizers, antioxidants, and ultraviolet absorbers, if necessary.

[0093] [Use of the organic light-emitting device according to one embodiment of the present invention] The organic light-emitting device according to one embodiment of the present invention can be used as a component of a display device or a lighting device, and can also be used as an exposure light source for an electrophotographic image forming device, a backlight for a liquid crystal display device, a light-emitting device having a white light source and a color filter, etc.

[0094] The display device may be an image information processing device that has an image input unit that inputs image information from an area CCD, a linear CCD, a memory card, etc., has an information processing unit that processes the input information, and displays the input image on the display unit.

[0095] The display unit of the imaging device or inkjet printer may have a touch panel function. The driving method of this touch panel function may be an infrared method, a capacitance method, a resistive film method, or an electromagnetic induction method, and is not particularly limited. The display device may also be used in the display unit of a multifunction printer.

[0096] Next, a display device according to the present embodiment will be described with reference to the drawings. The display device according to the present embodiment has a plurality of pixels, at least one of which has an organic light-emitting element according to an embodiment of the present invention and a transistor connected thereto.

[0097] 3 is a cross-sectional view showing an example of a display device having an organic light-emitting element and an active element connected to the organic light-emitting element. The active element may be a transistor or a TFT made of polysilicon, an oxide semiconductor, or the like.

[0098] 3 includes a substrate 11 made of glass or the like, and an insulating layer 12 formed thereon to protect the transistor element or organic compound layer. On the substrate 11, there is provided a transistor element 18 including a gate electrode 13, a gate insulating film 14, a semiconductor layer 15, a drain electrode 16, and a source electrode 17.

[0099] The display device has an organic light-emitting element 26 on a transistor element via an interlayer insulating layer 19. The organic light-emitting element 26 has an anode 21, an organic compound layer 22 including a light-emitting layer, and a cathode 23.

[0100] A contact hole 20 is provided in the interlayer insulating layer 19, and an anode 21 and a source electrode 17 that constitute the organic light-emitting element are connected via the contact hole.

[0101] The electrical connection method between the electrodes (anode, cathode) included in the organic light-emitting element and the electrodes (source electrode, drain electrode) included in the transistor is not limited to the embodiment shown in Fig. 3. In other words, it is sufficient that either the anode or the cathode is electrically connected to either the source electrode or the drain electrode of the transistor element.

[0102] 3, the organic compound layer 22 is illustrated as a single layer, but may be a multi-layer organic compound layer 22. A first protective layer 24 and a second protective layer 25 are provided on the cathode 23 to suppress deterioration of the organic light-emitting element.

[0103] In the display device 10 of FIG. 3, transistors are used as switching elements, but other elements may be used as switching elements instead.

[0104] The transistors used in the display device 10 of Fig. 3 are not limited to transistors using single-crystal silicon wafers, but may also be thin-film transistors having an active layer on an insulating surface of a substrate. Examples of active layers include single-crystal silicon, amorphous silicon, microcrystalline silicon, and other non-single-crystal silicon, as well as non-single-crystal oxide semiconductors such as indium zinc oxide and indium gallium zinc oxide. Thin-film transistors are also called TFT elements.

[0105] The transistors included in the display device 10 of FIG. 3 may be formed within a substrate such as a Si substrate. Here, "formed within a substrate" means that the substrate itself, such as a Si substrate, is processed to form the transistors. In other words, having a transistor within a substrate can be seen as the substrate and the transistor being integrally formed. Whether to provide a transistor within the substrate or a TFT is determined by the size of the display unit. For example, for a display size of about 0.5 inches, it is preferable to provide an organic light-emitting element on a Si substrate.

[0106] The organic light-emitting element according to this embodiment has its light-emitting luminance controlled by a transistor, which is an example of a switching element, and by providing a plurality of organic light-emitting elements on a surface, an image can be displayed using the respective light-emitting luminances.

[0107] 4 is a schematic diagram illustrating an example of a display device according to this embodiment. The display device 1000 may have a touch panel 1003, a display panel 1005, a frame 1006, a circuit board 1007, and a battery 1008 between an upper cover 1001 and a lower cover 1009. The touch panel 1003 and the display panel 1005 are connected by flexible printed circuits FPCs 1002 and 1004. Transistors are printed on the circuit board 1007. The battery 1008 may not be provided if the display device is not a portable device, and may be provided in a different position even if the display device is a portable device.

[0108] The display device according to this embodiment may be used in a display unit of an imaging device having an optical unit with multiple lenses and an imaging element that receives light that has passed through the optical unit. The imaging device may have 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 located within the viewfinder. The imaging device may be a digital camera or a digital video camera. The imaging device may also be called a photoelectric conversion device.

[0109] 4A is a schematic diagram showing an example of an imaging device according to this embodiment. The imaging device 1100 may include a viewfinder 1101, a rear display 1102, an operation unit 1103, and a housing 1104. The viewfinder 1101 may include a display device according to this embodiment. In this case, the display device may display not only an image to be captured, but also environmental information, imaging instructions, and the like. The environmental information may include the intensity of external light, the direction of external light, the speed at which the subject is moving, the possibility that the subject will be blocked by an obstruction, and the like.

[0110] Since the optimum timing for capturing an image is very short, it is better to display information as soon as possible. Therefore, it is preferable to use a display device using an organic light-emitting element according to one embodiment of the present invention. This is because organic light-emitting elements have a fast response speed. A display device using an organic light-emitting element can be used more preferably than a liquid crystal display device, which requires a high display speed.

[0111] The imaging device 1100 has an optical section (not shown). The optical section has multiple lenses, which form an image on an imaging element housed in a housing 1104. The focus of the multiple lenses can be adjusted by adjusting their relative positions. This operation can also be performed automatically.

[0112] The display device according to this embodiment may have color filters having red, green, and blue colors, which may be arranged in a delta arrangement.

[0113] The display device according to the present embodiment may be used as a display unit of a mobile terminal. In this case, the display device may have both a display function and an operation function. Examples of the mobile terminal include a mobile phone such as a smartphone, a tablet, and a head-mounted display.

[0114] FIG. 4(b) is a schematic diagram showing an example of an electronic device according to this embodiment. The electronic device 1200 has a display unit 1201, an operation unit 1202, and a housing 1203. The housing 1203 may have a circuit, a printed circuit board having the circuit, a battery, and a communication unit. The operation unit 1202 may be a button or a touch panel type reaction unit. The operation unit may be a biometric recognition unit that recognizes a fingerprint to perform operations such as unlocking. An electronic device having a communication unit can also be called a communication device.

[0115] 5A and 5B are schematic diagrams illustrating an example of a display device according to this embodiment. Fig. 5A shows a display device such as a television monitor or a PC monitor. The display device 1300 has a frame 1301 and a display unit 1302. The light-emitting device according to this embodiment may be used in the display unit 1302.

[0116] It has a frame 1301 and a base 1303 that supports a display unit 1302. The base 1303 is not limited to the form shown in Fig. 5(a). The bottom side of the frame 1301 may also serve as the base.

[0117] The frame 1301 and the display unit 1302 may be curved. The radius of curvature may be 5000 mm or more and 6000 mm or less.

[0118] FIG. 5(b) is a schematic diagram illustrating another example of a display device according to this embodiment. The display device 1310 in FIG. 5(b) is configured to be bendable, and is a so-called foldable display device. The display device 1310 has a first display unit 1311, a second display unit 1312, a housing 1313, and a bending point 1314. The first display unit 1311 and the second display unit 1312 may include a light-emitting device according to this embodiment. The first display unit 1311 and the second display unit 1312 may be a single, seamless display unit. The first display unit 1311 and the second display unit 1312 can be separated by the bending point. The first display unit 1311 and the second display unit 1312 may each display different images, or the first and second display units may display a single image.

[0119] FIG. 6(a) is a schematic diagram illustrating an example of a lighting device according to this embodiment. The lighting device 1400 may include a housing 1401, a light source 1402, a circuit board 1403, an optical film 1404, and a light diffusion unit 1405. The light source may include an organic light-emitting element according to this embodiment. The optical filter may be a filter that improves the color rendering of the light source. The light diffusion unit can effectively diffuse light from the light source, such as for illumination, and deliver the light over a wide area. The optical filter and the light diffusion unit may be provided on the light emission side of the lighting. If necessary, a cover may be provided on the outermost part.

[0120] The lighting device is, for example, a device for illuminating a room. The lighting device may emit white, daylight white, or any other color from blue to red. It may have a dimming circuit for dimming these colors. The lighting device may have the organic light-emitting element of the present invention and a power supply circuit connected thereto. The power supply circuit is a circuit for converting AC voltage to DC voltage. Furthermore, white has a color temperature of 4200K, and daylight white has a color temperature of 5000K. The lighting device may have a color filter.

[0121] The lighting device according to this embodiment may also include a heat dissipation unit, which dissipates heat from within the device to the outside, and may be made of a material such as a metal with a high specific heat capacity or liquid silicon.

[0122] 6(b) is a schematic diagram of an automobile, which is an example of a moving body according to this embodiment. The automobile has tail lamps, which are an example of lighting fixtures. The automobile 1500 has tail lamps 1501, and may be configured to turn on the tail lamps when braking or the like is performed.

[0123] A tail lamp 1501 may include an organic light-emitting element according to this embodiment. The tail lamp may include a protective member for protecting the organic light-emitting element. The protective member may be made of any material as long as it has a certain degree of strength and is transparent, but it is preferably made of polycarbonate or the like. Polycarbonate may be mixed with a furandicarboxylic acid derivative, an acrylonitrile derivative, or the like.

[0124] An automobile 1500 may have a body 1503 and a window 1502 attached thereto. The window may be a transparent display as long as it is not a window for checking the front and rear of the automobile. The transparent display may have an organic light-emitting element according to this embodiment. In this case, constituent materials of the electrodes and the like of the organic light-emitting element are made of transparent materials.

[0125] The moving body according to this embodiment may be a ship, an aircraft, a drone, or the like. The moving body may have a body and a lighting device provided on the body. The lighting device may emit light to indicate the position of the body. The lighting device has the organic light-emitting element according to this embodiment.

[0126] As described above, by using a device using the organic light-emitting element according to this embodiment, it is possible to provide a stable display with good image quality even over a long period of time. [Example]

[0127] Example 1 In this example, an organic light-emitting element having a top-emission structure was fabricated, in which an anode, a hole injection layer, a hole transport layer, an electron blocking layer, a first light-emitting layer, a second light-emitting layer, a first electron transport layer, a second electron transport layer, an electron injection layer, and a cathode were sequentially formed on a substrate.

[0128] A 40 nm Ti film was formed on a glass substrate by sputtering and patterned using photolithography to form an anode. At this time, the electrode area of the opposing electrode (metal electrode layer, cathode) was 3 mm. 2 It was made to be like this.

[0129] Next, the substrate with the cleaned electrodes and the material were placed in a vacuum deposition device (manufactured by ULVAC), and a 1.33 × 10 -4 Pa(1×10 -6 After evacuating the chamber to a pressure of 1000 Torr, the chamber was subjected to UV / ozone cleaning. Thereafter, each layer was formed according to the layer structure shown in Table 1 below.

[0130] [Table 1]

[0131] Thereafter, the substrate was transferred to a glove box and sealed with a glass cap containing a desiccant in a nitrogen atmosphere to obtain a white organic light-emitting device.

[0132] The obtained white organic light-emitting device was connected to a voltage application device, and its characteristics were evaluated. The current-voltage characteristics were measured using a Hewlett-Packard 4140B microcurrent meter, and the luminance was measured using a Topcon BM7.

[0133] In addition, the initial brightness is 1000 cd / m2 A continuous driving test was conducted at 100 hours, and the deterioration rate of brightness after 100 hours was measured. If the deterioration rate was 20% or more, it was marked "X", if the deterioration rate was 10% or more but less than 20%, it was marked "△", and if the deterioration rate was 5% or more but less than 10%, it was marked "◯". If the deterioration rate was less than 5%, it was marked "◎". The results are shown in Table 2 below.

[0134] (Examples 2 to 7, Comparative Examples 1 to 5) Devices were prepared in the same manner as in Example 1, except that the first electron transporting layer, second electron transporting layer, and light-emitting layer host A were changed to the compounds shown in Table 3 below. The results are shown in Table 2 together with those of Example 1.

[0135] [Table 2]

[0136] (Examples 8 to 10, Comparative Examples 6 to 8) In Example 8, each layer was formed with the layer structure shown in Table 3 below. The results are shown in Table 4 together with the results of other Examples.

[0137] Furthermore, devices were prepared in the same manner as in Example 8, except that the first electron transporting layer, the second electron transporting layer, and the host A in the light-emitting layer were changed to the compounds shown in Table 4 below.

[0138] The obtained blue organic light-emitting device was connected to a voltage application device, and its characteristics were evaluated. The current-voltage characteristics were measured using a Hewlett-Packard 4140B microcurrent meter, and the luminance was measured using a Topcon BM7.

[0139] In addition, the initial brightness is 300 cd / m 2 A continuous driving test was carried out at 100 hours, and the deterioration rate of brightness after 100 hours was measured. If the deterioration rate was 20% or more, it was marked "X", if the deterioration rate was 10% or more but less than 20%, it was marked "△", and if the deterioration rate was 5% or more but less than 10%, it was marked "◯". If the deterioration rate was less than 5%, it was marked "◎". The results are shown in Table 5 below. The same evaluation as in Example 1 was carried out. The results are shown in Table 5.

[0140]

Table 3

[0141]

Table 4

[0142] (Example 11) <Evaluation of HOMO> The host and dopant were evaluated by the method shown below.

[0143] A thin film of the compound to be measured with a thickness of 30 nm was formed on an aluminum substrate, and this thin film was measured using AC-3 (manufactured by Riken Keiki Co., Ltd.). The results are shown in Table 5.

[0144]

Table 5

[0145] As in the examples, in the organic light-emitting device of the present invention, low-voltage and high-efficiency light emission could be confirmed by making the first electron transport layer and the second electron transport layer into a mixed layer. On the other hand, it was found that the voltage increased when at least one of the electron transport layers was not a mixed layer, as in the comparative examples. Furthermore, it was found that a compound composed of a hydrocarbon containing no nitrogen-containing aromatic compound had a better lifetime than a compound containing a nitrogen-containing aromatic compound in the first electron transport layer.

[0146] In addition, it was found that the lifetime and efficiency were particularly good in the case of an element having the relationship of HOMO: (host material A) < (electron transport material A) < (electron transport material B).

Explanation of Reference Signs

[0147] 1 Insulating layer 2 Anode 3 Hole injection layer 4 Electron blocking layer 5 Light-emitting layer 6 First electron transport layer 7 Second electron transport layer 8 Electron injection layer 9 Cathode 10 Display device 11 Circuit Board 12 Insulating layer 13 Gate electrode 14 Gate insulating film 15 Semiconductor layer 16 Drain electrode 17 Source electrode 18 Transistor element 19 Interlayer insulating layer 20 Contact Hole 21 Anode 22 Organic compound layer 23 Cathode 24 First Layer of Protection 25 Second Layer of Protection 26 Organic light-emitting devices 1000 display devices 1001 Top cover 1002 Flexible Printed Circuit 1003 Touch Panel 1004 Flexible Printed Circuit 1005 Display panel 1006 frames 1007 Circuit Board 1008 Battery 1009 Lower cover 1100 Imaging device 1101 Viewfinder 1102 Rear display 1103 Operation unit 1104 Case 1200 Electronic equipment 1201 Display section 1202 Operation unit 1203 Case 1300 display device 1301 Picture Frame 1302 Display section 1303 Foundation 1310 Display device 1311 First display section 1312 Second display section 1313 Case 1314 bending point 1400 lighting equipment 1401 Case 1402 Light source 1403 Circuit Board 1404 Optical film 1405 Light diffusion part 1500 cars 1501 tail lamp 1502 Window 1503 Body

Claims

1. An organic light-emitting device having an anode, a light-emitting layer, a first electron transport layer, a second electron transport layer, and a cathode in this order, the second electron transport layer comprises a first material and a second material different from the first material; the first electron transport layer comprises a third material and a fourth material different from the third material; the light-emitting layer comprises a fifth material; The organic light-emitting device is characterized in that the first material to the fifth material satisfy the following relationship: | HOMO (first ingredient) | > | HOMO (second ingredient) | > | HOMO (fourth ingredient) | | HOMO (first ingredient) | > | HOMO (third ingredient) | > | HOMO (fourth ingredient) | | HOMO (second ingredient) | > | HOMO (fifth ingredient) | Here, |HOMO (first material)|, |HOMO (second material)|, |HOMO (third material)|, |HOMO (fourth material)|, and |HOMO (fifth material)| represent the absolute value of the HOMO energy of the first material, the absolute value of the HOMO energy of the second material, the absolute value of the HOMO energy of the third material, the absolute value of the HOMO energy of the fourth material, and the absolute value of the HOMO energy of the fifth material, respectively.

2. The organic light-emitting device according to claim 1 , wherein the light-emitting layer and the first electron transport layer are provided in contact with each other.

3. An organic light-emitting device having an anode, a light-emitting layer, a first electron transport layer, a second electron transport layer, and a cathode in this order, the light-emitting layer and the first electron transport layer are provided in contact with each other, the second electron transport layer comprises a first material and a second material different from the first material; the first electron transport layer comprises a third material and a fourth material different from the third material; The organic light-emitting device is characterized in that the first material to the fourth material satisfy the following relationship: | HOMO (first ingredient) | > | HOMO (second ingredient) | > | HOMO (fourth ingredient) | | HOMO (first ingredient) | > | HOMO (third ingredient) | > | HOMO (fourth ingredient) | Here, |HOMO (first material)|, |HOMO (second material)|, |HOMO (third material)|, and |HOMO (fourth material)| represent the absolute value of the HOMO energy of the first material, the absolute value of the HOMO energy of the second material, the absolute value of the HOMO energy of the third material, and the absolute value of the HOMO energy of the fourth material, respectively.

4. 4. The organic light-emitting element according to claim 1, wherein the first material to the fourth material satisfy the following relationship: |HOMO (first ingredient) |>|HOMO (second ingredient) |=|HOMO (third ingredient) |>|HOMO (fourth ingredient) |

5. 5. The organic light-emitting device according to claim 1, wherein the second material and the third material are the same material.

6. The organic light-emitting device according to claim 1 , wherein the first electron transport layer and the second electron transport layer are provided in contact with each other.

7. the light-emitting layer comprises a fifth material; 7. The organic light-emitting device according to claim 1, wherein the fourth material and the fifth material are the same compound.

8. 2. The organic light-emitting device according to claim 1, wherein an organic compound layer between the first electron transport layer and the light-emitting layer and different from the first electron transport layer and the light-emitting layer is a hole-blocking layer.

9. 9. The organic light-emitting element according to claim 1, wherein at least one of the third material and the fourth material is an organic compound.

10. The organic light-emitting element according to claim 7, wherein the light-emitting layer further contains a sixth material, and the fifth material has a larger weight ratio in the light-emitting layer than the sixth material when the weight of the light-emitting layer is taken as 100 wt %.

11. The organic light-emitting device according to claim 10, wherein the sixth material is a light-emitting material.

12. 12. The organic light-emitting device according to claim 1, wherein the second material is a hydrocarbon compound.

13. 13. The organic light-emitting device according to claim 1, wherein the first material is a heterocyclic compound.

14. 14. The organic light-emitting device according to claim 13, wherein the heterocyclic compound is a compound having a nitrogen atom as a heteroatom.

15. 15. The organic light-emitting element according to claim 1, wherein the second material has an aryl group, and the aryl group may have an alkyl group having 1 to 12 carbon atoms as a substituent, and the aryl group is selected from benzene, naphthalene, fluorene, benzofluorene, phenanthrene, chrysene, triphenylene, pyrene, fluoranthene, and benzofluoranthene.

16. The organic light-emitting element according to claim 7 , wherein the fifth material is a hydrocarbon compound.

17. 17. The organic light-emitting element according to claim 1, wherein the anode is a light-reflecting electrode and the cathode is a light-transmitting electrode.

18. The organic light-emitting element according to any one of claims 1 to 17, wherein the light-emitting layer comprises at least two layers.

19. A display device comprising a plurality of pixels, at least one of the plurality of pixels comprising the organic light-emitting element according to claim 1 and a transistor connected to the organic light-emitting element.

20. an optical unit having a plurality of lenses, an image pickup element that receives light that has passed through the optical unit, and a display unit that displays an image picked up by the image pickup element; The photoelectric conversion device, wherein the display section comprises the organic light-emitting element according to claim 1 .

21. 19. An electronic device comprising: a display unit having the organic light-emitting element according to claim 1; a housing in which the display unit is provided; and a communication unit provided in the housing and communicating with an external device.

22. 19. A lighting device comprising: a light source having the organic light-emitting element according to claim 1; and a light diffusion section or an optical film that transmits light emitted from the light source.

23. A moving body comprising: a lamp having the organic light-emitting element according to claim 1; and a vehicle on which the lamp is provided.

24. a photosensitive member and an exposure light source that exposes the photosensitive member; 19. An image forming apparatus, wherein the exposure light source comprises the organic light emitting element according to claim 1.

Images